List of Issues

2021, Vol. 54, No. 3　Online: 15 March 2021

Previous Issue    Next Issue

For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

Select

Construction of cobalt-copper bimetallic oxide heterogeneous nanotubes for high-efficient and low-overpotential electrochemical CO2 reduction Zhong Cheng, Xiaodeng Wang, Hengpan Yang, Xinyao Yu, Qing Lin, Qi Hu, Chuanxin He 2021, 54(3): 1-6.  DOI: 10.1016/j.jechem.2020.04.018 Abstract ( 17 )   PDF (3184KB) ( 9 )

Select

Conversion of ethanol to 1,3-butadiene over Ag-ZrO2/SiO2 catalysts: The role of surface interfaces Houqian Li, Jifeng Pang, Nicholas R. Jaegers, Libor Kovarik, Mark Engelhard, Anthony W. Savoy, Jianzhi Hu, Junming Sun, Yong Wang 2021, 54(3): 7-15.  DOI: 10.1016/j.jechem.2020.05.038 Abstract ( 5 )   PDF (3548KB) ( 2 )   A series of Ag-ZrO2/SiO2 catalysts with different metal-support interfaces were synthesized in an effort to elucidate the roles of specific interfaces in controlling the ethanol to 1,3-butadiene conversion and selectivity. According to the results of detailed characterizations (e.g. CO/pyridine-DRIFTS, XPS, TEM, NH3-TPD, and 1H MAS NMR), it was found that the Ag-O-Si interfaces significantly enhanced the dehydrogenation of ethanol while the presence of ZrO2 improved the interaction between Ag and ZrO2/SiO2, creating more Agδ+ active sites. The high dispersion of ZrO2 on SiO2 generated abundant Zr-O-Si interfaces with medium and weak Lewis acidity, promoting the condensation of acetaldehyde to crotonaldehyde. These Zr-O-Si interfaces in close interaction with Agδ+ species played a critical role in the enhanced H transfer during the MPV reduction of crotonaldehyde to crotyl alcohol. The synergies among the interfaces resulted in retarded ethanol dehydration reactivity, balanced ethanol dehydrogenation and condensation reactions, and a subsequent high 1,3-butadiene yield.

Select

TiN nanocrystal anchored on N-doped graphene as effective sulfur hosts for high-performance lithium-sulfur batteries Wenmiao Chen, Hongchang Jin, Shuai Xie, Huanyu Xie, Junfa Zhu, Hengxing Ji, Li-Jun Wan 2021, 54(3): 16-22.  DOI: 10.1016/j.jechem.2020.05.007 Abstract ( 4 )   PDF (4059KB) ( 2 )   Lithium-sulfur (Li-S) batteries have become prospective candidates for next-generation energy storage owing to the high energy density and low cost. However, the sluggish kinetics of the electrochemical reaction and shuttle effect result in a rapid capacity decay. Herein, a titanium nitride nanocrystal/N-doped graphene (TiN@NG) composite is developed to host elemental sulfur. The TiN nanoparticles decorated on graphene sheets attract Li polysulfides (LiPSx) and catalyze the electrochemical reduction and oxidation of LiPSx in the discharge and charge processes, respectively. These two effects effectively restrain the dissolution of the LiPSx and accelerate the electrochemical reactions, thereby, alleviating the shuttle effect. As a result, the cathode composed of TiN@NG/S delivers a remarkable reversible capacity (1390 mA h g-1 at 0.1 C) and excellent cycling performance (730 mA h g-1 after 300 cycles). We believe that this work can bring some inspiration for designing high-performance Li-S batteries.

Select

Groups-dependent phosphines as the organic redox for point defects elimination in hybrid perovskite solar cells Zhengli Wu, Miao Zhang, Yifan, Liu, Yuxi Dou, Yinjie Kong, Lin Gao, Weitao Han, Guijie Liang, XiaoLi Zhang, Fuzhi Huang, Yi-Bing Cheng, Jie Zhong 2021, 54(3): 23-29.  DOI: 10.1016/j.jechem.2020.05.047 Abstract ( 9 )   PDF (4199KB) ( 3 )   Lead (Pb)0 and iodine (I)0 point defects generated during perovskite solar cell (PSC) fabrication and photoconversion form deep band energy levels as the carriers’ recombination centers. These defects not only deteriorate device efficiency, but also facilitate chemical degradation with ion migration, resulting in restricted device lifetime. Herein, we present a novel type of phosphines as the point defects stabilizer for hybrid perovskite solar cells with enhanced performances. Three phosphines with varied side groups of tributyl, trioctyl and triphenyl are exampled as the dopants in perovskite films. The group dependent redox properties were observed in the perovskite film, dependent on their molecular weights and steric hinderances of phosphines. The partially oxidized tributyl phosphine (TBUP) with additional tributyl phosphine oxides (TBPO) is efficient in reduction of lead (Pb)0 and iodine (I)0 concentrations during the device fabrication and operation. The device with TBUP-TBPO pair showed enhanced power conversion efficiency (PCE) to 20.48% and maintain 91.7% of their initial PCEs after 500 h at 65 °C thermal annealing. Thus, this work presents an efficient route of utilize the phosphine species to reduce point defects in the perovskite film, which promoting further development of novel phosphorous additives with defects stabilization, interface passivation and encapsulation for low-cost solution processed PSCs.

Select

Tri-profit electrolysis for energy-efficient production of benzoic acid and H2 Chi Zhang, Suqin Ci, Xinxin Peng, Junheng Huang, Pingwei Cai, Yichun Ding, Zhenhai Wen 2021, 54(3): 30-35.  DOI: 10.1016/j.jechem.2020.04.073 Abstract ( 11 )   PDF (3807KB) ( 5 )

Select

Self-assembled synthesis of oxygen-doped g-C3N4 nanotubes in enhancement of visible-light photocatalytic hydrogen Yizeng Zhang, Zhiwu Chen, Jinliang Li, Zhenya Lu, Xin Wang 2021, 54(3): 36-44.  DOI: 10.1016/j.jechem.2020.05.043 Abstract ( 7 )   PDF (4944KB) ( 3 )   Currently, photocatalytic water splitting is regarded as promising technology in renewable energy generation. However, the conversion efficiency suffers great restriction due to the rapid recombination of charge carriers. Rational designed the structure and doping elements become important alternative routes to improve the performance of photocatalyst. In this work, we rational designed oxygen-doped graphitic carbon nitride (OCN) nanotubes derived from supermolecular intermediates for photocatalytic water splitting. The as prepared OCN nanotubes exhibit an outstanding hydrogen evolution rate of 73.84 μmol h-1, outperforming the most of reported one dimensional (1D) g-C3N4 previously. Due to the rational oxygen doping, the band structure of g-C3N4 is meliorated, which can narrow the band gap and reduce the recombination rate of photogenerated carriers. Furthermore, the hollow nanotube structure of OCN also provide multiple diffuse reflection during photocatalytic reaction, which can significantly promote the utilization capacity of visible light and enhance the photocatalytic water splitting performance. It is believed that our work not only rationally controls the nanostructure, but also introduces useful heteroatom into the matrix of photocatalyst, which provides an effective way to design high-efficiency g-C3N4 photocatalyst.

Select

Biopolymer passivation for high-performance perovskite solar cells by blade coating Shudi Qiu, Xin Xu, Linxiang Zeng, Zhen Wang, Yijun Chen, Cuiling Zhang, Chaohui Li, Jinlong Hu, Tingting Shi, Yaohua Mai, Fei Guo 2021, 54(3): 45-52.  DOI: 10.1016/j.jechem.2020.05.040 Abstract ( 5 )   PDF (3322KB) ( 2 )   Thin films of perovskite deposited from solution inevitably introduce large number of defects, which serve as recombination centers and are detrimental for solar cell performance. Although many small molecules and polymers have been delicately designed to migrate defects of perovskite films, exploiting credible passivation agents based on natural materials would offer an alternative approach. Here, an eco-friendly and cost-effective biomaterial, ploy-l-lysine (PLL), is identified to effectively passivate the defects of perovskite films prepared by blade-coating. It is found that incorporation of a small amount (2.5 mg mL-1) of PLL significantly boosts the performance of printed devices, yielding a high efficiency of 19.45% with an increase in open-circuit voltage by up to 100 mV. Density functional theory calculations combined with X-ray photoelectron spectroscopy reveal that the functional groups (-NH2, -COOH) of PLL effectively migrate the Pb-I antisite defects via Pb-N coordination and suppress the formation of metallic Pb in the blade-coated perovskite film. This work suggests a viable avenue to exploit passivation agents from natural materials for preparation of high-quality perovskite layers for optoelectronic applications.

Select

Characterization of porous cobalt hexacyanoferrate and activated carbon electrodes under dynamic polarization conditions in a sodium-ion pseudocapacitor Bruno Morandi Pires, Willian Gonçalves Nunes, Bruno Guilherme Freitas, Francisca Elenice Rodrigues Oliveira, Vera Katic, Cristiane Barbieri Rodella, Leonardo Morais Da Silva, Hudson Zanin 2021, 54(3): 53-62.  DOI: 10.1016/j.jechem.2020.05.045 Abstract ( 3 )   PDF (3387KB) ( 4 )   We report here the activated carbon and cobalt hexacyanoferrate composite, which is applied as the electrode materials in symmetric supercapacitors containing a 1.0 M Na2SO4 aqueous electrolyte. This novel material combines high specific surface area and electrochemical stability of activated carbon with the redox properties of cobalt hexacyanoferrate, resulting in maximum specific capacitance of 329 F g-1 with large voltage working window of 2.0 V. Electrochemical studies indicated that cobalt hexacyanoferrate introduces important pseudocapacitive properties accounting for the overall charge-storage process, especially when I < 0.5 A g-1. At lower gravimetric currents (e.g., 0.05 A g-1) and up to 1.0 V, the presence of cobalt hexacyanoferrate improves the specific energy for more than 300%. In addition, to better understanding the energy storage process we also provided a careful investigation of the electrode materials under dynamic polarization conditions using the in situ Raman spectroscopy and synchrotron light X-ray diffraction techniques. Interesting complementary findings were obtained in these studies. We believe that this novel electrode material is promising for applications regarding the energy-storage process in pseudocapacitors with long lifespan properties.

Select

CoNi nanoparticles anchored inside carbon nanotube networks by transient heating: Low loading and high activity for oxygen reduction and evolution Chengfeng Zhu, Wei Yang, Jiangtao Di, Sha Zeng, Jian Qiao, Xiaona Wang, Bo Lv, Qingwen Li 2021, 54(3): 63-71.  DOI: 10.1016/j.jechem.2020.05.052 Abstract ( 2 )   PDF (4062KB) ( 2 )   Transitional metal alloy and compounds have been developed as the low cost and efficient bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). However, a high mass loading of these catalysts is commonly needed to achieve acceptable catalytic performance, which could cause such problems as battery weight gain, mass transport blocking, and catalyst loss. We report herein the preparation of fine CoNi nanoparticles (5-6 nm) anchored inside a nitrogen-doped defective carbon nanotube network (CoNi@N-DCNT) by a transient Joule heating method. When utilized as an electrocatalyst for oxygen reduction and evolution in alkaline media, the CoNi@N-DCNT film catalyst with a very low mass loading of 0.06 mg cm-2 showed excellent bifunctional catalytic performance. For ORR, the onset potential (Eonset) and the half-wave potential (E1/2) were 0.92 V versus reversible hydrogen electrode (vs. RHE) and 0.83 V (vs. RHE), respectively. For OER, the potential at the current density (J) of 10 mA cm-2 (E10) was 1.53 V, resulting in an overpotential of 300 mV much lower than that of the commercial RuO2 catalyst (320 mV). The potential gap between E1/2 and E10 was as small as 0.7 V. Considering the low mass loading, the mass activity at E10 reached at 123.2 A g-1, much larger than that of the RuO2 catalyst and literature results of transitional metal-based bifunctional catalysts. Moreover, the CoNi@N-DCNT film catalyst showed very good long-term stability during the ORR and OER test. The excellent bifunctional catalytic performance could be attributed to the synergistic effect of the bimetal alloy.

Select

Recent progress on discovery and properties prediction of energy materials: Simple machine learning meets complex quantum chemistry Yongqiang Kang, Lejing Li, Baohua Li 2021, 54(3): 72-88.  DOI: 10.1016/j.jechem.2020.05.044 Abstract ( 7 )   PDF (16744KB) ( 1 )   In nature, the properties of matter are ultimately governed by the electronic structures. Quantum chemistry (QC) at electronic level matches well with a few simple physical assumptions in solving simple problems. To date, machine learning (ML) algorithm has been migrated to this field to simplify calculations and improve fidelity. This review introduces the basic information on universal electron structures of emerging energy materials and ML algorithms involved in the prediction of material properties. Then, the structure-property relationships based on ML algorithm and QC theory are reviewed. Especially, the summary of recently reported applications on classifying crystal structure, modeling electronic structure, optimizing experimental method, and predicting performance is provided. Last, an outlook on ML assisted QC calculation towards identifying emerging energy materials is also presented.

Select

Surface/interface engineering of high-efficiency noble metal-free electrocatalysts for energy-related electrochemical reactions Hui Zhao, Zhong-Yong Yuan 2021, 54(3): 89-104.  DOI: 10.1016/j.jechem.2020.05.048 Abstract ( 6 )   PDF (5275KB) ( 2 )   To date, much efforts have been devoted to the high-efficiency noble metal-free electrocatalysts for hydrogen- and oxygen-involving energy conversion reactions, due to their abundance, low cost and multifunctionally. Surface/interface engineering is found to be effective in achieving novel physicochemical properties and synergistic effects in nanomaterials for electrocatalysis. Among various engineering strategies, heteroatom-doping has been regarded as a most promising method to improve the electrocatalytic performance via the regulation of electronic structure of catalysts, and numerous works were reported on the synthesis method and mechanism investigation of heteroatom-doping electrocatalysts, though the heteroatom-doping can only provide limited active sites. Engineering of other defects such as vacancies and edge sites and construction of heterostructure have shown to open up a potential avenue for the development of noble metal-free electrocatalysts. In addition, surface functionalization can attach various molecules onto the surface of materials to easily modify their physical or chemical properties, being as a promising complement or substitute for offering materials with catalytic properties. This paper gives the insights into the diverse strategies of surface/interface engineering of the high-efficiency noble metal-free electrocatalysts for energy-related electrochemical reactions. The significant advances are summarized. The unique advantages and mechanisms for specific applications are highlighted. The current challenges and outlook of this growing field are also discussed.

Select

Vesicle-shaped ZIF-8 shell shielded in 3D carbon cloth for uniform nucleation and growth towards long-life lithium metal anode Yuting Fang, Wenlong Cai, Shanshan Zhu, Kangli Xu, Maogen Zhu, Guannan Xiao, Yongchun Zhu 2021, 54(3): 105-110.  DOI: 10.1016/j.jechem.2020.05.067 Abstract ( 7 )   PDF (2744KB) ( 4 )   Lithium metal has aroused extensive research interests as the anode for next-generation rechargeable batteries. However, the well-known dendritic Li growth and consequent safety issues still impair the long-term cycling performance. Herein, a hybrid structure composed of 3D carbon cloth and vesicle-shaped hollow ZIF-8 modification shell (HZS@CC) was prepared as a smart host for guiding uniform Li deposition. The long-range interconnected 3D carbon fiber network enables the reduced local current density with homogeneous electrons distribution. Synergistically, abundant surface polar groups and the ultrastructure on ZIF-8 particles effectively guide a well-distributed Li-ions flow to promote the uniform Li nucleation and growth. As a result, stable Li plating/stripping for 2000 h with a low overpotential (≈15 mV) at 1 mA cm-2 were achieved in symmetric cells. Coupling with LiFePO4 cathode, the full cell delivered long life over 1200 cycles at 6 C. This research demonstrated that a homogenization guiding of Li-ions is of great importance to better make use of the structural advantage of 3D hosts and achieve improved electrochemical performance.

Select

Conversion of CO2 and H2 into propane over InZrOx and SSZ-13 composite catalyst Zhaopeng Liu, Youming Ni, Tantan Sun, Wenliang Zhu, Zhongmin Liu 2021, 54(3): 111-117.  DOI: 10.1016/j.jechem.2020.04.069 Abstract ( 5 )   PDF (3619KB) ( 2 )   Direct converting carbon dioxide into hydrocarbon fuels and value-added chemicals would offer a very attractive approach for efficient utilization of CO2 as a carbon resource. Although, olefins, aromatics and gasoline have been successfully synthesized by CO2 hydrogenation, highly selective conversion of CO2 and H2 into C2+ hydrocarbon is still challenging due to a high C-C coupling barrier and inhibiting the production of other long-chain hydrocarbons. Here, we report a composite catalyst made of InZrOx and SSZ-13 molecular sieve (InZrOx + SSZ-13), which exhibits 74.5% propane selectivity at 623 K. The 8-MR micropores and the higher strength of the acid for SSZ-13 benefit the formation of propane. Compared with pure InOx and m-ZrO2, the composite oxide InZrOx containing more oxygen vacancies, exhibits to be more readily reduced by H2 and easier to adsorb and desorb CO2 within the reaction temperature. All those could be beneficial to the activation and conversion of H2 and CO2. The catalytic performance of InZrOx + SSZ-13 in CO2 hydrogenation provides a potential for production of propane.

Select

Defect engineering of single-walled carbon nanohorns for stable electrochemical synthesis of hydrogen peroxide with high selectivity in neutral electrolytes Yang Liu, Jianshuo Zhang, Suqiong He, Yaqi Cui, Lunhui Guan 2021, 54(3): 118-123.  DOI: 10.1016/j.jechem.2020.05.033 Abstract ( 6 )   PDF (3182KB) ( 2 )

Select

Unraveling the stabilization mechanism of solid electrolyte interface on ZnSe by rGO in sodium ion battery Shuang Men, Hui Zheng, Dejun Ma, Xiaolian Huang, Xiongwu Kang 2021, 54(3): 124-130.  DOI: 10.1016/j.jechem.2020.05.046 Abstract ( 6 )   PDF (1564KB) ( 4 )   Transition metal selenides have been widely studied as anode materials of sodium ion batteries (SIBs), however, the investigation of solid-electrolyte-interface (SEI) on these materials, which is critical to the electrochemical performance of SIBs, remains at its infancy. Here in this paper, ZnSe@C nanoparticles were prepared from ZIF-8 and the SEI layers on these electrodes with and without reduced graphene oxide (rGO) layers were examined in details by X-ray photoelectron spectroscopies at varied charged/discharged states. It is observed that fast and complicated electrolyte decomposition reactions on ZnSe@C leads to quite thick SEI film and intercalation of solvated sodium ions through such thick SEI film results in slow ion diffusion kinetics and unstable electrode structure. However, the presence of rGO could efficiently suppress the decomposition of electrolyte, thus thin and stable SEI film was formed. ZnSe@C electrodes wrapped by rGO demonstrates enhanced interfacial charge transfer kinetics and high electrochemical performance, a capacity retention of 96.4%, after 1000 cycles at 5 A/g. This study might offer a simple avenue for the designing high performance anode materials through manipulation of SEI film.

Select

Heating induced aggregation in non-fullerene organic solar cells towards high performance Baocai Du, Renyong Geng, Wenliang Tan, Yuchao Mao, Donghui Li, Xue Zhang, Dan Liu, Weihua Tang, Wenchao Huang, Tao Wang 2021, 54(3): 131-137.  DOI: 10.1016/j.jechem.2020.05.054 Abstract ( 6 )   PDF (6295KB) ( 3 )   Molecular ordering within the photoactive layer plays a crucial role in determining the device performance of organic solar cells (OSCs). However, the simultaneous molecular ordering processes of polymer donors and non-fullerene acceptors (NFAs) during solution casting usually bring confinement effect, leading to insufficient structural order of photovoltaic components. Herein, the molecular packing of m-INPOIC NFA is effectively formed through a heating induced aggregation strategy, with the aggregation of PBDB-T, which has a strong temperature dependence, is retarded by casting on a preheated substrate to reduce its interference toward m-INPOIC. A sequent thermal annealing treatment is then applied to promote the ordering of PBDB-T and achieve balanced aggregation of both donors and acceptors, resulting in the achievement of a maximum efficiency of 13.9% of PBDB-T:m-INPOIC binary OSCs. This work disentangles the interactions of donor polymer and NFA during the solution casting process and develops a rational strategy to enhance the molecular packing of NFAs to boost device performance.

Select

Pampas grass-inspired FeOOH nanobelts as high performance anodes for sodium ion batteries Lianyi Shao, Shige Wang, Fangdan Wu, Xiaoyan Shi, Zhipeng Sun, Yuxin Tang 2021, 54(3): 138-142.  DOI: 10.1016/j.jechem.2020.05.051 Abstract ( 4 )   PDF (2835KB) ( 3 )

Select

Boosting electrocatalytic activity for CO2 reduction on nitrogen-doped carbon catalysts by co-doping with phosphorus Shuo Chen, Tianfu Liu, Samson O. Olanrele, Zan Lian, Chaowei Si, Zhimin Chen, Bo Li 2021, 54(3): 143-150.  DOI: 10.1016/j.jechem.2020.05.006 Abstract ( 3 )   PDF (2510KB) ( 3 )   Electrochemical reduction of CO2 (CERR) to value-added chemicals is an attractive strategy for greenhouse gas mitigation, and carbon recycles utilization. Conventional metal catalysts suffered from low durability and sluggish kinetics impede the practical application. On the other hand, doped carbon materials recently demonstrate superior catalytic performance in CERR, which shows the potential to diminish the problems of metal catalysts to some extent. Herein, we present the design and fabrication of nitrogen (N), phosphorus (P) co-doped metal-free carbon materials as an efficient and stable electrocatalyst for reduction of CO2 to CO, which exhibits an excellent performance with a high faradaic efficiency of 92% (-0.55 V vs. RHE) and up to 24 h stability. A series of characterizations including TEM and XPS verified that nitrogen and phosphorous are successfully incorporated into the carbon matrix. Moreover, the comparisons between co-doping and single doping catalysts reveal that co-doping can significantly increase CERR performance. The improved catalytic activity is attributed to the synergetic effects between nitrogen and phosphorous dopants, which effectively modulate properties of the active site. The density functional theory (DFT) calculations were also performed to understand the synergy effects of dopants. It is revealed that the phosphorous doping can significantly lower the Gibbs free energy of COOH* formation. Moreover, the introduction of the second dopants phosphorous can reduce the reaction barrier along the reaction path and cause polarization of density of states at the Fermi level. These changes can greatly enhance the activity of the catalysts. From a combined experimental and computational exploration, current work provides valuable insights into the reaction mechanism of CERR on N, P co-doped carbon catalysts, and the influence from synergy effects between dopants, which paves the way for the rational design of novel metal-free catalysts for CO2 electro-reduction.

Select

Current advancements on charge selective contact interfacial layers and electrodes in flexible hybrid perovskite photovoltaics Gopalan Saianand, Prashant Sonar, Gregory J. Wilson, Anantha-Iyengar Gopalan, Vellaisamy A.L. Roy, Gautam E. Unni, KhanMamun Reza, Behzad Bahrami, K. Venkatramanan, Qiquan Qiao 2021, 54(3): 151-173.  DOI: 10.1016/j.jechem.2020.05.050 Abstract ( 7 )   PDF (10170KB) ( 2 )   Perovskite-based photovoltaic materials have been attracting attention for their strikingly improved performance at converting sunlight into electricity. The beneficial and unique optoelectronic characteristics of perovskite structures enable researchers to achieve an incredibly remarkable power conversion efficiency. Flexible hybrid perovskite photovoltaics promise emerging applications in a myriad of optoelectronic and wearable/portable device applications owing to their inherent intriguing physicochemical and photophysical properties which enabled researchers to take forward advanced research in this growing field. Flexible perovskite photovoltaics have attracted significant attention owing to their fascinating material properties with combined merits of high efficiency, light-weight, flexibility, semi-transparency, compatibility towards roll-to-roll printing, and large-area mass-scale production. Flexible perovskite-based solar cells comprise of 4 key components that include a flexible substrate, semi-transparent bottom contact electrode, perovskite (light absorber layer) and charge transport (electron/hole) layers and top (usually metal) electrode. Among these components, interfacial layers and contact electrodes play a pivotal role in influencing the overall photovoltaic performance. In this comprehensive review article, we focus on the current developments and latest progress achieved in perovskite photovoltaics concerning the charge selective transport layers/electrodes toward the fabrication of highly stable, efficient flexible devices. As a concluding remark, we briefly summarize the highlights of the review article and make recommendations for future outlook and investigation with perspectives on the perovskite-based optoelectronic functional devices that can be potentially utilized in smart wearable and portable devices.

Select

Formaldehyde intermediate participating in the conversion of methanol to aromatics over zinc modified H-ZSM-5 Youming Ni, Wenliang Zhu, Zhongmin Liu 2021, 54(3): 174-178.  DOI: 10.1016/j.jechem.2020.05.063 Abstract ( 2 )   PDF (1455KB) ( 3 )   Metal-modified H-ZSM-5 has a high selectivity of aromatics in methanol to aromatics (MTA) reaction, which is often attributed to the metal promoting the aromatization of intermediate olefins. However, the effect of methanol dehydrogenation on aromatics formation over these catalysts is rarely studied. Here, we report that HCHO, which is formed by methanol dehydrogenation over Zn/H-ZSM-5 prepared by Zn impregnation, can participate in the synthesis of aromatics. Methanol conversion can produce more aromatics than olefins (propylene or ethylene) conversion over Zn/H-ZSM-5, indicating the conventional MTA pathway including methanol-to-olefins and olefins-to-aromatics is not complete. Moreover, an MTA mechanism including the conventional pathway and the methanol and HCHO coupling pathway is systematically proposed.

Select

Nanostructured strategies towards boosting organic lithium-ion batteries Yujing Liu, Guoyuan Sun, Xiaohan Cai, Fan Yang, Cong Ma, Min Xue, Xinyong Tao 2021, 54(3): 179-193.  DOI: 10.1016/j.jechem.2020.05.021 Abstract ( 4 )   PDF (10493KB) ( 1 )   Pursuing material development for next-generation batteries, organic electrode materials have shown great potential for lithium-ion batteries. However, their widespread adopting is plagued by intrinsic problems such as poor electronic conductivity, high dissolution inside electrolytes and unstable chemical peculiarity. Recently, nanostructured-strategies promoted organic electrodes with exotic properties for enhancing electron and ion transport together with the stability during electrochemical process, have received increasing attention and have been extensive applied in boosting the organic lithium-ion based energy storage. In this review, we summarize the applications of nanostructures to improve the performance of both organic anodes and cathodes, including (i) nanoscale design of zero-dimensional organic electrode materials, (ii) strategies of one-dimensional nanostructured organic electrode materials, (iii) construction of two-dimensional nanosized organic composite electrodes, and (iv) three-dimensional exploration of nanosized organic electrodes. We hope to stimulate high-quality applied research on understanding and handling the relationship between the nanostructure and performance of organic lithium-ion batteries that might speed up the commercialization of organic lithium ion batteries.

Select

From aqueous Zn-ion battery to Zn-MnO2 flow battery: A brief story Tong Xue, Hong Jin Fan 2021, 54(3): 194-201.  DOI: 10.1016/j.jechem.2020.05.056 Abstract ( 3 )   PDF (4074KB) ( 2 )   Aqueous Zn-ion battery (AZIB) has become an attractive technology because of its unique features of low cost, high safety and the eco-friendliness. MnO2 is the model cathode material for AZIB since the first report on reversible Zn-MnO2 battery, but recent studies have unveiled different charge storage mechanisms. Due to revamping of the electrochemistry and redesigning of the electrolyte and interface, there is tremendous performance enhancement in AZIB. This mini Review will first give a brief introduction of ZIB, including fundamentals of materials and components, and the progress in recent years. Then, a general classification of working mechanisms related to MnO2 in neutral and mildly acidic electrolyte is elaborated. Our focus is put on the recent blossoming Zn-MnO2 electrolytic mechanism, which has given birth to the Zn-MnO2 redox flow batteries that are highly promising for large-scale static energy storage.

Select

Insight into the hydrogen oxidation electrocatalytic performance enhancement on Ni via oxophilic regulation of MoO2 Shaofeng Deng, Xupo Liu, Xuyun Guo, Tonghui Zhao, Yun Lu, Jingyu Cheng, Ke Chen, Tao Shen, Ye Zhu, Deli Wang 2021, 54(3): 202-207.  DOI: 10.1016/j.jechem.2020.05.066 Abstract ( 4 )   PDF (4554KB) ( 2 )   Exploring platinum-group-metal (PGM) free electrocatalysts for hydrogen oxidation reaction (HOR) in alkaline media is essential to the progress of anion exchange membrane fuel cells (AEMFCs). In this work, a Ni/MoO2 heterostructure catalyst with comparable HOR activity in alkaline electrolyte with PGM catalyst was prepared by a simple hydrothermal-reduction method. Remarkably, the Ni/MoO2 presents a mass kinetic current density of 38.5 mA mgNi-1 at the overpotential of 50 mV, which is higher than that of the best PGM free HOR catalyst reported by far. Moreover, the HOR performance of Ni/MoO2 under 100 ppm CO shows negligible fading, together with the superior durability, render it significant potential for application in AEMFCs. A particular mechanistic study indicates that the excellent HOR performance is ascribed to the accelerated Volmer step by the incorporation of MoO2. The function of MoO2 was further confirmed by CO striping experiment on Pt/C-MoO2 that MoO2 can facilitated OH adsorption thus accelerate the HOR process. On account of the high performance and low cost, the Ni/MoO2 electrocatalyst encourages the establishment of high performance PGM free catalyst and shows significant potential for application in AEMFCs.

Select

Effects of structure and electronic properties of D-π-A organic dyes on photovoltaic performance of dye-sensitized solar cells Min-Woo Lee, Jae-Yup Kim, Hyung-Geun Lee, Hyun Gil Cha, Duck-Hyung Lee, Min Jae Ko 2021, 54(3): 208-216.  DOI: 10.1016/j.jechem.2020.05.060 Abstract ( 6 )   PDF (3603KB) ( 2 )   Herein, we examine the performance of dye-sensitized solar cells containing five D-π-A organic dyes designed by systematic modification of π-bridge size and geometric structure. Each dye has a simple push-pull structure with a triarylamino group as an electron donor, bithiophene-4,4-dimethyl-4H-cyclopenta[1,2-b:5,4-b’]dithiophene (M11), 4,4-dimethyl-4H-cyclopenta[1,2-b:5,4-b’]dithiophene-thiophene (M12), thiophene-4,4-dimethyl-4H-cyclopenta[1,2-b:5,4-b’]dithiophene (M13), 4,4-dimethyl-4H-cyclopenta[1,2-b:5,4-b’]dithiophene-benzene (M14), and 4,4-dimethyl-4H-cyclopenta[1,2-b:5,4-b’]dithiophene (M15) units as π-bridges, and cyanoacrylic acid as an electron acceptor/anchor. The extension of the π-bridge linkage favors wide-range absorption but, because of the concomitant molecular volume increase, hinders the efficient adsorption of dyes on the TiO2 film surface. Hence, higher loadings are achieved for smaller dye molecules, resulting in (i) a shift of the TiO2 conduction band edge to more negative values, (ii) a greater photocurrent, and (iii) suppressed charge recombination between the photoanode and the redox couple in the electrolyte. Consequently, under one-sun equivalent illumination (AM 1.5 G, 100 mW/cm2), the highest photovoltage, photocurrent, and conversion efficiency (η = 7.19%) are observed for M15, which has the smallest molecular volume among M series dyes.

Select

A bifunctional perovskite oxide catalyst: The triggered oxygen reduction/evolution electrocatalysis by moderated Mn-Ni co-doping Jia Sun, Lei Du, Baoyu Sun, Guokang Han, Yulin Ma, Jiajun Wang, Hua Huo, Pengjian Zuo, Chunyu Du, Geping Yin 2021, 54(3): 217-224.  DOI: 10.1016/j.jechem.2020.05.064 Abstract ( 5 )   PDF (12226KB) ( 1 )   ABO3-type perovskite oxides (e.g., LaCoO3) with flexible and adjustable A- and B-sites are ideal model catalysts to unravel the relationship between the electronic structure and electrocatalytic activity (e.g., oxygen reduction/evolution reactions, ORR/OER). It has been well understood in our recent work that the secondary metal dopant at B-site (e.g., Mn in LaMnxCo1-xO3) can regulate the electronic structure and improve the ORR/OER activity. In this work, the Mn-Ni pairs are employed as the dual dopant in LaMnxNiyCozO3 (x + y + z = 1) catalysts toward bifunctional ORR and OER. The structure-property relationships between the triple metal B-site (Mn, Ni and Co) and the electrochemical performance are particularly investigated. Compared to the individual Mn doping (e.g., LaMnCoO3 (Mn:Co = 1:3) catalyst), the dual Mn-Ni doping significantly improves the ORR mass activity@0.8 V by 1.54 times; meanwhile, the OER overpotential@10 mA cm-2 is reduced from 420 to 370 mV, and the OER current density at 1.55 V is increased by 2.43 times. Reasonably, the potential gap between EORR@-1 mA cm-2 and EOER@10 mA cm-2 is achieved as only 0.76 V by using the optimal LaMnxNiyCozO3 (x:y:z = 1:2:3) catalyst. It is revealed that the dual Mn-Ni dopant efficiently optimizes electron structures of the LaMnNiCoO3 (1:2:3) catalyst, which not only decreases the eg orbital electron number, but also modulates the O 2p-band closer to the Femi level, accounting for the enhanced bifunctional activity.

Select

Recent advances in electrospun electrode materials for sodium-ion batteries Yao Wang, Yukun Liu, Yongchang Liu, Qiuyu Shen, Chengcheng Chen, Fangyuan Qiu, Ping Li, Lifang Jiao, Xuanhui Qu 2021, 54(3): 225-241.  DOI: 10.1016/j.jechem.2020.05.065 Abstract ( 7 )   PDF (9214KB) ( 5 )   Sodium-ion batteries (SIBs) have been considered as an ideal choice for the next generation large-scale energy storage applications owing to the rich sodium resources and the analogous working principle to that of lithium-ion batteries (LIBs). Nevertheless, the larger size and heavier mass of Na+ ion than those of Li+ ion often lead to sluggish reaction kinetics and inferior cycling life in SIBs compared to the LIB counterparts. The pursuit of promising electrode materials that can accommodate the rapid and stable Na-ion insertion/extraction is the key to promoting the development of SIBs toward a commercial prosperity. One-dimensional (1D) nanomaterials demonstrate great prospects in boosting the rate and cycling performances because of their large active surface areas, high endurance for deformation stress, short ions diffusion channels, and oriented electrons transfer paths. Electrospinning, as a versatile synthetic technology, features the advantages of controllable preparation, easy operation, and mass production, has been widely applied to fabricate the 1D nanostructured electrode materials for SIBs. In this review, we comprehensively summarize the recent advances in the sodium-storage cathode and anode materials prepared by electrospinning, discuss the effects of modulating the spinning parameters on the materials’ micro/nano-structures, and elucidate the structure-performance correlations of the tailored electrodes. Finally, the future directions to harvest more breakthroughs in electrospun Na-storage materials are pointed out.

Select

Advances in in-situ characterizations of electrode materials for better supercapacitors Xiaoli Su, Jianglin Ye, Yanwu Zhu 2021, 54(3): 242-253.  DOI: 10.1016/j.jechem.2020.05.055 Abstract ( 4 )   PDF (3371KB) ( 2 )   In past decades, the performance of supercapacitors has been greatly improved by rationalizing the electrode materials at the nanoscale. However, there is still a lack of understanding on how the charges are efficiently stored in the electrodes or transported across the electrolyte/electrode interface. As it is very challenging to investigate the ion-involved physical and chemical processes with single experiment or computation, combining advanced analytic techniques with electrochemical measurements, i.e., developing in-situ characterizations, have shown considerable prospect for the better understanding of behaviors of ions in electrodes for supercapacitors. Herein, we briefly review several typical in-situ techniques and the mechanisms these techniques reveal in charge storage mechanisms specifically in supercapacitors. Possible strategies for designing better electrode materials are also discussed.

Select

Carbon-containing electrospun nanofibers for lithium-sulfur battery: Current status and future directions Zhaoming Tong, Liang Huang, WenLei, Haijun Zhang, Shaowei Zhang 2021, 54(3): 254-273.  DOI: 10.1016/j.jechem.2020.05.059 Abstract ( 7 )   PDF (8742KB) ( 2 )   Lithium-sulfur batteries (LSBs) have become promising next-generation energy storage technologies for electric vehicles and portable electronics, due to its excellent theoretical specific energy. However, the low conductivity of sulfur species, notorious lithium dendrites, the severe “shuttle effect” of polysulfides (LiPSs) and the inferior kinetic reaction for LiPSs/Li2S conversion during discharge-charge have seriously hindered their practical application, and also pose potential safety hazards. Owing to their superior porous architectures, high specific surface areas, excellent structural designability, functional modifiability, abundant active sites and flexibility of carbon-containing electrospun nanofibers (CENFs), they exhibited the superior characteristics that can simultaneously solve the above issues. In this review, we summarize the recent progress and application of CENFs in LSBs. First, we provide a brief introduction to the structure and composition controlled of carbon nanofibers by electrospinning. We then review progress in recent developments of CENFs for LSBs including cathodes, anodes, separators, and interlayers. We focus on how to solve practical issues that arise when the CENFs are applied to various parts of LSBs, and the relevant working mechanisms are described, from high sulfur loading and Li dendrites suppression to LiPSs’ confinement and conversion. Finally, we summarize and propose the existing challenges and future prospects of CENFs, for the design and architecture of electrochemical components in Li-S energy storage systems.

Select

Surpassing electrocatalytic limit of earth-abundant Fe4+ embedded in N-doped graphene for (photo)electrocatalytic water oxidation Wenjia Xue, Feng Cheng, Menglu Li, Wenjian Hu, Congping Wu, Bing Wang, Kuowei Liao, ZhenTao Yu, Yingfang Yao, Wenjun Luo, Zhigang Zou 2021, 54(3): 274-281.  DOI: 10.1016/j.jechem.2020.05.053 Abstract ( 6 )   PDF (3966KB) ( 2 )   Developing highly active, cost-effective, and environmental friendly oxygen evolution reaction (OER) electrocatalysts facilitates various (photo)electrochemical processes. In this work, Fe3N nanoparticles encapsulated into N-doped graphene nanoshells (Fe3N@NG) as OER electrocatalysts in alkaline media were reported. Both the experimental and theoretical comparison between Fe3N@NG and Fe3N/NG, specifically including in situ Mössbauer analyses, demonstrated that the NG nanoshells improved interfacial electron transfer process from Fe3N to NG to form high-valence Fe4+ ions (Fe4+@NG), thus modifying electronic properties of the outer NG shells and subsequently electron transfer from oxygen intermediate to NG nanoshells for OER catalytic process. Meanwhile, the NG nanoshells also protected Fe-based cores from forming OER inactive and insulated Fe2O3, leading to high OER stability. As a result, the as-formed Fe4+@NG shows one of the highest electrocatalytic efficiency among reported Fe-based OER electrocatalysts, which can as well highly improve the photoelectrochemical water oxidation when used as the co-catalysts for the Fe2O3 nanoarray photoanode.

Select

Ag-modified hydrogen titanate nanowire arrays for stable lithium metal anode in a carbonate-based electrolyte Zhipeng Wen, Dongzheng Wu, Hang Li, Yingxin Lin, Hang Li, Yang Yang, Jinbao Zhao 2021, 54(3): 282-290.  DOI: 10.1016/j.jechem.2020.05.057 Abstract ( 2 )   PDF (6991KB) ( 2 )   In the investigation of the next-generation battery anode, Li metal has attracted increasing attention owing to its ultrahigh specific capacity and low reduction potential. However, its low columbic efficiency, limited cycling life, and serious safety hazards have hindered the practical application of rechargeable Li metal batteries. Although several strategies have been proposed to enhance the electrochemical performance of Li metal anodes, most are centered around ether-based electrolytes, which are volatile and do not provide a sufficiently large voltage window. Therefore, we aimed to attain stable Li deposition/stripping in a commercial carbonate-based electrolyte. Herein, we have successfully synthesized hydrogen titanate (HTO) nanowire arrays decorated with homogenous Ag nanoparticles (NPs) (Ag@HTO) via simple hydrothermal and silver mirror reactions. The 3D cross-linked array structure with Ag NPs provides preferable nucleation sites for uniform Li deposition, and most importantly, when assembled with the commercial LiNi0.5Co0.2Mn0.3O2 cathode material, the Ag@HTO could maintain a capacity retention ratio of 81.2% at 1 C after 200 cycles, however the pristine Ti foil failed to do so after only 60 cycles. Our research therefore reveals a new way of designing current collectors paired with commercial high voltage cathodes that can create high energy density Li metal batteries.

Select

Multifunctional dopamine-assisted preparation of efficient and stable perovskite solar cells Jiankai Zhang, Huangzhong Yu 2021, 54(3): 291-300.  DOI: 10.1016/j.jechem.2020.05.061 Abstract ( 3 )   PDF (7350KB) ( 2 )   Perovskite solar cells (PSCs) show great potential for next-generation photovoltaics, due to their excellent optical and electrical properties. However, defects existing inside the perovskite film impair both the performance and stability of the device. Uncoordinated Pb2+, uncoordinated I-, and metallic Pb (Pb0) are the main defects occur during perovskite film preparation and device operation, due to the volatilization of organic cationic components. Passivating these defects is a desirable task, because they are non-radiative recombination centers that cause open-circuit voltage (VOC) loss and degradation of the perovskite layer. Herein, the multifunctional bioactive compound dopamine (DA) is introduced for the first time to control the perovskite film formation and passivate the uncoordinated Pb2+ defects via Lewis acid-base interactions. The Pb0 and I- defects are effectively suppressed by the DA treatment. At the same time, the DA treatment results in a stronger crystal orientation along the (110) plane and upshifts the valence band of perovskite closer to the highest occupied molecular orbital (HOMO) of the hole transport layer (2,2′,7,7′-tetrakis(N,N′-di-pmethoxyphenylamine)-9,9′-spirobifluorene, spiro-OMeTAD), which is beneficial for charge separation and transport processes. Consequently, the stability of MAPbI3 (MA = CH3NH3) PSCs prepared with the DA additive (especially the thermal stability) is effectively improved due to the better crystallinity and lower number of defect trap states of the perovskite film. The optimized MAPbI3 PSCs maintain approximately 90% of their original power conversion efficiency (PCE) upon annealing at 85 °C for 120 h. The best performance triple-cation perovskite (Cs0.05(FA0.83MA0.17)0.95Pb(I0.83Br0.17)3) (FA = formamidinium) solar cell with ITO/SnO2/Cs0.05(FA0.83MA0.17)0.95Pb(I0.83Br0.17)3:DA/spiro-OMeTAD/MoO3/Ag (ITO = indium tin oxide) structure shows a PCE of 21.03% with negligible hysteresis, which is dramatically enhanced compared to that of the control device (18.31%). Therefore, this work presents a simple and effective way to improve the efficiency and stability of PSCs by DA treatment.

Select

A 3D conducting scaffold with in-situ grown lithiophilic Ni2P nanoarrays for high stability lithium metal anodes Huai Jiang, Hailin Fan, Zexun Han, Bo Hong, Feixiang Wu, Kai Zhang, Zhian Zhang, Jing Fang, Yanqing Lai 2021, 54(3): 301-309.  DOI: 10.1016/j.jechem.2020.06.004 Abstract ( 6 )   PDF (5600KB) ( 3 )   Lithium (Li) metal is the most potential anode material for the next-generation high-energy rechargeable batteries. However, intrinsic surface unevenness and ‘hostless’ nature of Li metal induces infinite volume effect and uncontrollable dendrite growth. Herein, we design the in-situ grown lithiophilic Ni2P nanoarrays inside nickel foam (PNF). Uniform Ni2P nanoarrays coating presents a very low nucleation overpotential, which induces the homogeneous Li deposition in the entire spaces of three-dimensional (3D) metal framework. Specifically, the lithiophilic Ni2P nanoarrays possess characteristics of electrical conductivity and structural stability, which have almost no expansion and damage during repeating Li plating/stripping. Therefore, they chronically inhibit the growth of Li dendrites. This results in an outstanding Coulombic efficiency (CE) of 98% at 3 mA cm-2 and an ultralong cycling life over 2000 cycles with a low overpotential. Consequently, the PNF-Li||LiFePO4 battery maintains a capacity retention of 95.3% with a stable CE of 99.9% over 500 cycles at 2C.

Select

In-situ self-templated preparation of porous core-shell Fe1-xS@N, S co-doped carbon architecture for highly efficient oxygen reduction reaction Zhi Li, Minjie Zhou, Binhong He, Wenqing Ren, Liang Chen, Wenyuan Xu, Zhaohui Hou, Yangyang Chen 2021, 54(3): 310-317.  DOI: 10.1016/j.jechem.2020.06.010 Abstract ( 4 )   PDF (6936KB) ( 3 )   Transition metal compound (TMC)/carbon hybrids, as prospering electrocatalyst, have attracted great attention in the field of oxygen reduction reaction (ORR). Their morphology, structure and composition often play a crucial role in determining the ORR performance. In this work, we for the first time report the successful fabrication of porous core-shell Fe1-xS@N, S co-doped carbon (Fe1-xS@NSC-t, t represents etching time) by a novel in-situ self-template induced strategy using Fe3O4 nanospheres and pyrrole as sacrificial self-template. The post-polymerization of pyrrole can be accomplished by the Fe3+ released through the etching of Fe3O4 by HCl acid. Thus, the etching time has a significant effect on the morphology, structure, composition and ORR performance of Fe1-xS@NSC-t. Based on the characterizations, we find Fe1-xS@NSC-24 can realize effective and balanced combination of Fe1-xS and NSC, possessing porous core-shell architecture, optimized structure defect, specific surface area and doped heteroatoms configurations (especially for pyridinic N, graphitic N and Fe-N structure). These features thus lead to outstanding catalytic activity and cycling stability towards ORR. Our work provides a good guidance on the design of TMC/carbon-based electrodes with unique stable morphology and optimized structure and composition.

Select

Zn nanosheets: An earth-abundant metallic catalyst for efficient electrochemical ammonia synthesis Qingqing Li, Jing Wang, Yonghua Cheng, Ke Chu 2021, 54(3): 318-322.  DOI: 10.1016/j.jechem.2020.06.011 Abstract ( 4 )   PDF (2359KB) ( 2 )

Select

Nickel nanoparticles supported on nitrogen-doped carbon nanotubes are a highly active, selective and stable CO2 methanation catalyst Julian Gödde, Mariia Merko, Wei Xia, Martin Muhler 2021, 54(3): 323-331.  DOI: 10.1016/j.jechem.2020.06.007 Abstract ( 10 )   PDF (2412KB) ( 2 )   CO2 methanation using nickel-based catalysts has attracted large interest as a promising power-to-gas route. Ni nanoparticles supported on nitrogen-doped CNTs with Ni loadings in the range from 10 wt% to 50 wt% were synthesized by impregnation, calcination and reduction and characterized by elemental analysis, X-ray powder diffraction, H2 temperature-programmed reduction, CO pulse chemisorption and transmission electron microscopy. The Ni/NCNT catalysts were highly active in CO2 methanation at atmospheric pressure, reaching over 50% CO2 conversion and over 95% CH4 selectivity at 340 °C and a GHSV of 50,000 mL g-1 h-1 under kinetically controlled conditions. The small Ni particle sizes below 10 nm despite the high Ni loading is ascribed to the efficient anchoring on the N-doped CNTs. The optimum loading of 30 wt%-40 wt% Ni was found to result in the highest Ni surface area, the highest degree of conversion and the highest selectivity to methane. A constant TOF of 0.3 s-1 was obtained indicating similar catalytic properties of the Ni nanoparticles in the range from 10 wt% to 50 wt% Ni loading. Long-term experiments showed that the Ni/NCNT catalyst with 30 wt% Ni was highly stable for 100 h time on stream.

Select

Precise in-situ and ex-situ study on thermal behavior of LiNi1/3Co1/3Mn1/3O2/graphite coin cell: From part to the whole cell Chen Liang, Lihua Jiang, Shuliang Ye, Zhaoyu Wang, Zesen Wei, Qingsong Wang, JinhuaSun 2021, 54(3): 332-341.  DOI: 10.1016/j.jechem.2020.06.008 Abstract ( 9 )   PDF (2195KB) ( 2 )   Multiple mode calorimetry and C80 micro-calorimeter are used to investigate the impact of cathode and anode on heat generation of lithium ion battery. The thermal behaviors of LiNixCoyMnzO2/graphite full cell are discussed under normal operating and elevating temperature. Affected by negative entropy change, lithium intercalation presents more exotherms than deintercalation for both electrode materials. The contributions of irreversible and reversible heat to the total heat generation of graphite are evaluated. The phase transitions correlated with voltages and lithium contents are determined. Based on the analysis of half-cell, the effect of two electrodes (with the same capacity) on overall heat generation is nearly the same and anode of full cell plays a key role in charging while cathode dominates in discharging. Thermal behaviors of lithiated graphite and delithiated LiNixCoyMnzO2, electrolyte and their coexisting system are identified to further explore their influence on battery safety. The breakdown of solid electrolyte interface (SEI) at around 82 °C is considered as a crucial factor affecting the thermal stability of full cell. The oxidation of electrolyte induced by oxygen released from cathode material turns out to be one of the main heat sources. These accurate results are of great significance to improve the existing thermal management system and provide basic data for the prediction of battery performance.

Select

Supported ionic liquid phase-boosted highly active and durable electrocatalysts towards hydrogen evolution reaction in acidic electrolyte Qiyou Wang, Yang Gao, Zhongyun Ma, Yan Zhang, Wenpeng Ni, Hussein A. Younus, Ce Zhang, Zhengjian Chen, Shiguo Zhang 2021, 54(3): 342-351.  DOI: 10.1016/j.jechem.2020.06.012 Abstract ( 10 )   PDF (4797KB) ( 3 )   Platinum is generally known as the most effective electrocatalyst for hydrogen evolution reaction because it can greatly lower the overpotential and accelerate the reaction kinetics, while its commercial potential always suffers from scarcity, high cost, low utilization, and poor durability particularly in acidic electrolytes. We herein demonstrate a facile method to improve the hydrogen evolution performance of Pt-based electrocatalysts by simply decorating the-state-of-the-art and commercially available Pt/C with hydrophobic protic ([DBU][NTf2]) or aprotic ([BMIm][NTf2]) ionic liquid. The current densities of [BMIm]@Pt/C and [DBU-H]@Pt/C with 10% ionic liquid at an overpotential of 40 mV are 2.81 and 4.15 times, respectively, higher than that of the pristine Pt/C. More importantly, ionic liquid-decoration significantly improves the long-term stability of Pt nanoparticles. After 8 h of chronoamperometric measurements, [DBU-H]@Pt/C and [BMIm]@Pt/C can still retain 83.7% and 78.3% of their original activity, respectively, which is much higher than that of the pristine Pt/C (24.4%). The improved performance of Pt/C decorated with ionic liquid is considered to arise from the improved proton conductivity (particularly for protic ionic liquid) and hydrophobic microenvironment created by the supported ionic liquid phase. The presence of ionic liquid layer not only de-coordinates H+ from hydronium ions nearby the Pt nanoparticles, but it also protects Pt nanoparticles from dissolution in the acidic media.

Select

Recent advances in carbon nanostructures prepared from carbon dioxide for high-performance supercapacitors Chen Li, Xiong Zhang, Kai Wang, Fangyuan Su, Cheng-Meng Chen, Fangyan Liu, Zhong-Shuai Wu, Yanwei Ma 2021, 54(3): 352-367.  DOI: 10.1016/j.jechem.2020.05.058 Abstract ( 8 )   PDF (6932KB) ( 4 )   The burgeoning global economy during the past decades gives rise to the continuous increase in fossil fuels consumption and rapid growth of CO2 emission, which demands an urgent exploration into green and sustainable devices for energy storage and power management. Supercapacitors based on activated carbon electrodes are promising systems for highly efficient energy harvesting and power supply, but their promotion is hindered by the moderate energy density compared with batteries. Therefore, scalable conversion of CO2 into novel carbon nanostructures offers a powerful alternative to tackle both issues: mitigating the greenhouse effect caused by redundant atmospheric CO2 and providing carbon materials with enhanced electrochemical performances. In this tutorial review, the techniques, opportunities and barriers in the design and fabrication of advanced carbon materials using CO2 as feedstock as well as their impact on the energy-storage performances of supercapacitors are critically examined. In particular, the chemical aspects of various CO2 conversion reactions are highlighted to establish a detailed understanding for the science and technology involved in the microstructural evolution, surface engineering and porosity control of CO2-converted carbon nanostructures. Finally, the prospects and challenges associated with the industrialization of CO2 conversion and their practical application in supercapacitors are also discussed.

Select

Carbon spheres with rational designed surface and secondary particle-piled structures for fast and stable sodium storage Wenlong Shao, Fangyuan Hu, Siyang Liu, Tianpeng Zhang, Ce Song, Zhihuan Weng, Jinyan Wang, Xigao Jian 2021, 54(3): 368-376.  DOI: 10.1016/j.jechem.2020.06.031 Abstract ( 8 )   PDF (5015KB) ( 4 )   The electrochemical performance of hard carbon in sodium storage is still limited by its poor cycling stability and rate capability because of the sluggish kinetics process. In this study, we use a simple and effective method to accelerate the kinetics process by engineering the structure of the electrode to promote its surface and near-surface reactions. This goal is realized by the use of slightly aggregated ultra-small carbon spheres. The large specific surface area formed by the small spheres can provide abundant active sites for electrochemical reactions. The abundant mesopores and macropores derived from the secondary particle piled structure of the carbon spheres could facilitate the transport of electrolytes, shorten the diffusion distance of Na+ and accommodate the volume expansion during cycling. Benefiting from these unique structure features, PG700-3 (carbon spheres with the diameters of 40-60 nm carbonized at 700 °C) exhibits high performance for sodium storage. A high reversible capacity of 163 mAh g-1 could be delivered at a current density of 1.0 A g-1 after 100 cycles. Interestingly, at a current density of 10.0 A g-1, the specific capacity of PG700-3 gradually increases to 140 mAh g-1 after 10 000 cycles, corresponding to a capacity retention of 112%. Given the enhanced kinetics of SIBs reactions, PG700-3 exhibits an excellent rate capability, i.e., 230 and 138 mAh g-1 at 0.1 and 5.0 A g-1, respectively. This study provides a facile method to attain high performance anode materials for SIBs. The design strategy and improvement mechanism could be extended to other materials for high rate applications.

Select

Search for potential K ion battery cathodes by first principles Kaining Li, Xiaofeng Fan, David J. Singh, W.T. Zheng 2021, 54(3): 377-385.  DOI: 10.1016/j.jechem.2020.06.003 Abstract ( 4 )   PDF (3298KB) ( 2 )   An important challenge facing K-ion batteries lies in exploring earth-abundant and safe cathode materials that can provide high capacity with high migration rate of K ions. Here, we propose a simple and efficient method for searching potential K cathode materials with first principles calculations. Our screening is based on combinations of weight capacity, K ion occupation ratio, volume change per K, and valence limit. With this screening method we predicted a series of potential K ions cathodes with favorable electrochemical performance, such as K2VPO4CO3-like structures with 1D diffusion channels, 3D channel structures K2CoSiO4, layered materials KCoO2, KCrO2, KVF4 and K5V3F14, and others. These potential cathodes have small volume changes, suitable voltage, and high capacity, with small diffusion barriers. They may be useful in K-ion batteries with high energy density and rate performance.

Select

Construction of hierarchical photocatalysts by growing ZnIn2S4 nanosheets on Prussian blue analogue-derived bimetallic sulfides for solar co-production of H2 and organic chemicals Liangxuan Zhong, Baodong Mao, Meng Liu, Mingyue Liu, Yaqiu Sun, Yi-Tao Song, Zhi-Ming Zhang, Tong-Bu Lu 2021, 54(3): 386-394.  DOI: 10.1016/j.jechem.2020.06.001 Abstract ( 3 )   PDF (4311KB) ( 2 )   Exploring highly efficient bifunctional photocatalysts for simultaneous H2 evolution and organic chemical production in pure water represents a green route for sustainable solar energy storage and conversion. Herein, a facile strategy was explored for preparing a hierarchical porous heterostructure of Fe4Ni5S8@ZnIn2S4 (FNS@ZIS) by the in situ growth of ZIS nanosheets on Prussian blue analogue (PBA)-derived bimetallic FNS sulfides. A series of FNS@ZIS hierarchical structures were facilely prepared by adjusting the loading amount (n%) of FNS (n = 19, 26, and 32 for FNS@ZIS-1-3). These structures can efficiently drive the solar co-production of H2 and organic chemicals. The optimal co-production was achieved with FNS@ZIS-2, affording a H2 evolution rate of 10465 μmol·g-1·h-1, along with high selectivity for the oxidation of benzyl alcohol to benzaldehyde (>99.9%). The performance was 22 and 31 times higher than that of FNS and ZIS, respectively, and even superior to the state-of-the-art results achieved using various sacrificial agents. Further mechanistic study indicated that the unique hierarchical core/shell architecture can facilitate interfacial charge separation, afford bimetallic synergy, abundant active sites and excellent photostability. This work highlights a simple and efficient method for preparing porous multimetallic hierarchical structures for the solar co-production of organic chemicals and H2 fuel.

Select

Pyridine-triphenylamine hole transport material for inverted perovskite solar cells Shuang Ma, Xianfu Zhang, Xuepeng Liu, Rahim Ghadari, Molang Cai, Yong Ding, Muhammad Mateen, Songyuan Dai 2021, 54(3): 395-402.  DOI: 10.1016/j.jechem.2020.06.002 Abstract ( 5 )   PDF (9473KB) ( 4 )   In the light of superior interaction between pyridine unit and perovskite, a facile star-shaped triphenylamine-based hole transport material (HTM) incorporating pyridine core (coded as H-Pyr) is designed and synthesized. A reference HTM with benzene core, coded as H-Ben, is also prepared for a comparative study. The effects of varying core on HTMs are investigated by comparing the photophysical, electrochemical and hole mobility properties. It is found that pyridine core exhibits better conjunction and decreased dihedral angles with triphenylamine side arms than that of benzene, leading to obviously better hole mobility and well-matched work function. The perovskite film prepared on H-Pyr also shows improved crystallization than on H-Ben. Photoluminescence and electrochemical impedance studies indicate improved charge extraction and reduced recombination in the H-Pyr-based perovskite solar cells. Consequently, H-Pyr-based device exhibits higher efficiency than H-Ben-based one. After doping with a Lewis acid, tris(pentafluorophenyl)borane, H-Pyr-based device delivers a champion efficiency of 17.09%, which is much higher compared with 12.14% of the device employing conventional poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as HTM. Moreover, the H-Pyr-based device displays good long-term stability that the power conversion efficiency remains over 80% of the initial value after storage in ambient (relative humidity = 50 ± 5%) for 20 days.

Select

Synthesis of carbon nitride in moist environments: A defect engineering strategy toward superior photocatalytic hydrogen evolution reaction Shuquan Huang, Feiyue Ge, Jia Yan, Hongping Li, Xingwang Zhu, Yuanguo Xu, Hui Xu, Huaming Li 2021, 54(3): 403-413.  DOI: 10.1016/j.jechem.2020.05.062 Abstract ( 8 )   PDF (6421KB) ( 2 )   Intimate understanding of the synthesis-structure-activity relationships is an accessible pathway to overcome the intrinsic challenges of carbon nitride (g-C3N4) photocatalysts. This work looks in the effects of humidity of the synthesis process to the morphology, chemical structure, band structure as well as the photocatalytic activity of g-C3N4 materials. Four g-C3N4 samples were prepared by heating melem in four gas environments: dry Ar, dry Air, moist Ar and moist Air. The photocatalytic activity measurements revealed that the samples synthesized in moist inert and oxidic gases environments displayed 20 and 10 times the photocatalytic H2 evolution activity of the samples synthesized in dry inert and oxidic gases environments, respectively. The reasons for this remarkable variety in photocatalytic activities had been through investigated. After all, the terminations of the carbon vacancies were identified as the dominant factor in enhancing H2 evolution performance. The work here thus demonstrating an example of defect engineering.

Select

Enhanced efficiency and stability in Sn-based perovskite solar cells with secondary crystallization growth Zhixin Jin, Bin-Bin Yu, Min Liao, Di Liu, Jingwei Xiu, Zheng Zhang, Efrat Lifshitz, Jiang Tang, Haisheng Song, Zhubing He 2021, 54(3): 414-421.  DOI: 10.1016/j.jechem.2020.06.044 Abstract ( 5 )   PDF (3375KB) ( 2 )   The conversion efficiencies reported for Tin (Sn) halide-based perovskite solar cells (PSCs) fall a large gap behind those of lead halide-based PSCs, mainly because of poor film quality of the former. Here we report an efficient strategy based on a simple secondary crystallization growth (SCG) technique to improve film quality for tin halide-based PSCs by applying a series of functional amine chlorides on the perovskite surface. They were discovered to enhance the film crystallinity and suppress the oxidation of Sn2+ remarkably, hence reduce trap state density and non-irradiative recombination in the absorber films. Furthermore, the SCG film holds the band levels matching better with carrier transport layers and herein favoring charge extraction at the device interfaces. Consequently, a champion device efficiency of 8.07% was achieved along with significant enhancements in Voc and Jsc, in contrast to 5.35% of the control device value. Moreover, the SCG film-based devices also exhibit superior stability comparing with the control one. This work explicitly paves a novel and general strategy for developing high performance lead-free PSCs.

Select

Nickel and indium core-shell co-catalysts loaded silicon nanowire arrays for efficient photoelectrocatalytic reduction of CO2 to formate Wenchao Ma, Mingcan Xie, Shunji Xie, Longfu Wei, Yichen Cai, Qinghong Zhang, Ye Wang 2021, 54(3): 422-428.  DOI: 10.1016/j.jechem.2020.06.023 Abstract ( 4 )   PDF (4657KB) ( 2 )   Developing an efficient artificial photosynthetic system for transforming carbon dioxide and storing solar energy in the form of chemical bonds is one of the greatest challenges in modern chemistry. However, the limited choice of catalysts with wide light absorption range, long-term stability and excellent selectivity for CO2 reduction makes the process sluggish. Here, a core-shell-structured non-noble-metal Ni@In co-catalyst loaded p-type silicon nanowire arrays (SiNWs) for efficient CO2 reduction to formate is demonstrated. The formation rate and Faradaic efficiency of formate over the Ni@In/SiNWs catalyst reach 58 μmol h-1 cm-2 and 87% under the irradiation of one simulated sunlight (AM 1.5G, 100 mW cm-2), respectively, which are about 24 and 12 times those over the pristine SiNWs. The enhanced photoelectrocatalytic performance for CO2 reduction is attributed to the rational combination of Ni capable of effectively extracting the photogenerated electrons and In responsible for the selective activation of CO2.

Select

Fischer-Tropsch reaction within zeolite crystals for selective formation of gasoline-ranged hydrocarbons Chengtao Wang, Wei Fang, Liang Wang, Feng-Shou Xiao 2021, 54(3): 429-433.  DOI: 10.1016/j.jechem.2020.06.006 Abstract ( 8 )   PDF (3572KB) ( 10 )   Product selectivity control is attractive in Fischer-Tropsch (F-T) synthesis but it is still a challenge, because the F-T products follow the Anderson-Schulz-Flory (ASF) distribution with maximized gasoline-ranged (C5-C11) hydrocarbon selectivity at 45%. Herein, we report a strategy by optimizing the gasoline selectivity to outperform the ASF limitation. The key to this success is fixation of the metal nanoparticles within zeolite crystals (metal@zeolite), where the zeolite micropore adjusts the product selectivity. For example, the Ru@NaY exhibited the gasoline selectivity 64.3% in the F-T reaction, which is significantly higher than the ASF limitation and about 2 times of that (32.8%) over conventionally supported Ru catalyst (Ru/NaY). This investigation might offer an alternative route for the direct transformation of syngas to liquid fuels with controllable selectivities.

Select

Catalyzing the polysulfide conversion for promoting lithium sulfur battery performances: A review Jingfa Li, Zhihao Niu, Cong Guo, Min Li, Weizhai Bao 2021, 54(3): 434-451.  DOI: 10.1016/j.jechem.2020.06.009 Abstract ( 4 )   PDF (17752KB) ( 2 )   Lithium-sulfur batteries (LSBs) are being recognized as potential successor to ubiquitous LIBs in daily life due to their higher theoretical energy density and lower cost effectiveness. However, the development of the LSB is beset with some tenacious issues, mainly including the insulation nature of the S or Li2S (the discharged product), the unavoidable dissolution of the reaction intermediate products (mainly as lithium polysulfides (LiPSs)), and the subsequent LiPSs shuttling across the separator, resulting in the continuous loss of active material, anode passivation, and low coulombic efficiency. Containment methods by introducing the high-electrical conductivity host are commonly used in improving the electrochemical performances of LSBs. However, such prevalent technologies are in the price of reduced energy density since they require more addition of amount of host materials. Adding trace of catalysts that catalyze the redox reaction between S/Li2S and Li2Sn (3 < n ≤ 8), shows ingenious design, which not only accelerates the conversion reaction between the solid S species and dissolved S species, alleviating the shuttle effect, but also expedites the electron transport thus reducing the polarization of the electrode. In this review, the redox reaction process during Li-S chemistry are firstly highlighted. Recent developed catalysts, including transition metal oxides, chalcogenides, phosphides, nitrides, and carbides/borides are then outlined to better understand the role of catalyst additives during the polysulfide conversion. Finally, the critical issues, challenges, and perspectives are discussed to demonstrate the potential development of LSBs.

Select

Single-atom catalysts for metal-sulfur batteries: Current progress and future perspectives Ru Xiao, Ke Chen, Xiaoyin Zhang, Zhenzhen Yang, Guangjian Hu, Zhenhua Sun, Hui-Ming Cheng, Feng Li 2021, 54(3): 452-466.  DOI: 10.1016/j.jechem.2020.06.018 Abstract ( 7 )   PDF (14769KB) ( 4 )   Metal-sulfur batteries are recognized as a promising candidate for next generation electrochemical energy storage systems owing to their high theoretical energy density, low cost and environmental friendliness. However, sluggish redox kinetics of sulfur species and the shuttle effect lead to large polarization and severe capacity decay. Numerous approaches from physical barrier, chemical adsorption strategies to electrocatalysts have been tried to solve these issues and pushed the rate and cycle performance of sulfur electrodes to higher levels. Most recently, single-atom catalysts (SACs) with high catalytic efficiency have been introduced into metal-sulfur systems to achieve fast redox kinetics of sulfur conversion. In this review, we systematically summarize the current progress on SACs for sulfur electrodes from aspects of synthesis, characterization and electrochemical performance. Challenges and potential solutions for designing SACs for high-performance sulfur electrodes are discussed.

Select

Improved interfacial property by small molecule ethanediamine for high performance inverted planar perovskite solar cells Guodong Zhang, Yunxin Zhang, Siqi Chen, Hao Chen, Le Liu, Wenming Ding, Jinhui Wang, Anyu Zhang, Shuping Pang, Xin Guo, Lianqing Yu, Tonggang Jiu 2021, 54(3): 467-474.  DOI: 10.1016/j.jechem.2020.06.029 Abstract ( 4 )   PDF (6164KB) ( 2 )   We report a simple and effective method to realize desirable interfacial property for inverted planar perovskite solar cells (PSCs) by using small molecule ethanediamine for the construction of a novel polyelectrolyte hole transport material (P3CT-ED HTM). It is found that P3CT-ED can not only improve the hole transport property of P3CT-K but also improve the crystallinity of adjacent perovskite film. In addition, the introduction of ethanediamine into P3CT realigns the conduction and valence bands upwards, passivates surface defects and reduces nonradiative recombination. As a consequence, compared to P3CT-K hole transport layer (HTL) based devices, the average power conversion efficiency (PCE) is boosted from 17.2% to 19.6% for the counterparts with P3CT-ED, with simultaneous enhancement in open circuit voltage and fill factor. The resultant device displays a champion PCE of 20.5% with negligible hysteresis.

Select

Molten salt synthesis of α-MnO2/Mn2O3 nanocomposite as a high-performance cathode material for aqueous zinc-ion batteries Aixiang Huang, Weijun Zhou, Anran Wang, Minfeng Chen, Qinghua Tian, Jizhang Chen 2021, 54(3): 475-481.  DOI: 10.1016/j.jechem.2020.06.041 Abstract ( 5 )   PDF (7659KB) ( 4 )   Thanks to low cost, high safety, and large energy density, aqueous zinc-ion batteries have attracted tremendous interest worldwide. However, it remains a challenge to develop high-performance cathode materials with an appropriate method that is easy to realize massive production. Herein, we use a molten salt method to synthesize nanostructured manganese oxides. The crystalline phases of the manganese oxides can be tuned by changing the amount of reduced graphene oxide added to the reactant mixture. It is found that the α-MnO2/Mn2O3 nanocomposite with the largest mass ratio of Mn2O3 delivers the best electrochemical performances among all the products. And its rate capability and cyclability can be significantly improved by modifying the Zn anode with carbon black coating and nanocellulose binder. In this situation, the nanocomposite can deliver high discharging capacities of 322.1 and 213.6 mAh g-1 at 0.2 and 3 A g-1, respectively. After 1000 cycles, it can retain 86.2% of the capacity at the 2nd cycle. Thus, this nanocomposite holds great promise for practical applications.

Select

Multi-heteroatom doped porous carbon derived from insect feces for capacitance-enhanced sodium-ion storage Chen Chen, Ying Huang, Zhuoyue Meng, Zhipeng Xu, Panbo Liu, Tiehu Li 2021, 54(3): 482-492.  DOI: 10.1016/j.jechem.2020.06.025 Abstract ( 5 )   PDF (8765KB) ( 4 )   The large-scale application of sodium ion batteries (SIBs) is limited by economic and environmental factors. Here, we prepare multi-heteroatom self-doped hierarchical porous carbon (HHPC) with a honeycomb-like structure by one-step carbonization method using high-yield and low-cost biomass silkworm excrement as a precursor. As an anode for SIB, HHPC-1100 exhibits a capacity of 331.7 mA h g-1 at 20 mA g-1, while it also reveals remarkable rate performance and stable long cycle capability due to its abundant pore structure and proper amount of hetero atom doping. Moreover, the synergistic effect of O, N, S, P co-doping in carbon materials on sodium ion adsorption is verified by the first-principles study, which provide a theoretical basis for the prominent electrochemical performance of the material.

Select

Evaporated potassium chloride for double-sided interfacial passivation in inverted planar perovskite solar cells Shasha Zhang, Xiaobo Yan, Zonghao Liu, Hongmei Zhu, Zhichun Yang, Yuqian Huang, Sanwan Liu, Di Wu, Ming Pan, Wei Chen 2021, 54(3): 493-500.  DOI: 10.1016/j.jechem.2020.06.019 Abstract ( 5 )   PDF (3941KB) ( 2 )   Defect-induced charge carrier recombination at the interfaces between perovskite and adjacent charge transport layers restricts further improvements in the device performance of perovskite solar cells (PSCs). Defect passivation at these interfaces can reduce trap states and inhibit the induced nonradiative recombination. Herein, we report a double-sided interfacial passivation via simply evaporating potassium chloride (DIP-KCl) at both the hole transport layer (HTL)/perovskite and perovskite/electron transport layer (ETL) interfaces in inverted planar PSCs. We demonstrate that the bottom KCl layer at the HTL/perovskite interface not only reduces the interfacial defects and improves the interfacial contact, but also leads to increased perovskite crystallinity, while the top KCl layer at the perovskite/ETL interface efficiently passivates the perovskite top surface defects and facilitates electron extraction at this interface. Thus, suppressed nonradiative recombination and faster charge extraction at both interfaces close to the perovskite layer can be achieved by using our DIP-KCl strategy. As a result, inverted PSCs based on DIP-KCl present an increased efficiency from 17.1% to 19.2% and enhanced stability, retaining over 90% of their initial efficiency after aging at maximum power point tracking for 1000 h. This work provides a simple and efficient way for defect passivation to further increase the efficiency and stability of PSCs.

Select

Theoretical screening of the transition metal heteronuclear dimer anchored graphdiyne for electrocatalytic nitrogen reduction Dongwei Ma, Zaiping Zeng, Liangliang Liu, Yu Jia 2021, 54(3): 501-509.  DOI: 10.1016/j.jechem.2020.06.032 Abstract ( 10 )   PDF (6426KB) ( 2 )   Developing efficient electrocatalysts for nitrogen reduction reaction (NRR) is crucial to replace the both energy-intensive and environment-malignant Haber-Bosch process. Here using density functional theory calculations, we systematically studied the potential of the heteronuclear 3d transition metal dimers anchored graphdiyne monolayers (FeM@and NiM@GDY, M = Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) as efficient NRR catalysts. Among all the studied double-atom catalysts (DACs), FeCo@and NiCo@GDY are the most promising with excellent NRR catalytic activity, high ability to suppress the competing hydrogen evolution reaction (HER), and good stability. For both FeCo@and NiCo@GDY, NRR prefers to the distal pathway with the calculated onset potentials of -0.44 and -0.36 V, respectively, which are comparable and even better than their homonuclear counterparts. Moreover, FeCo@and NiCo@GDY have higher ability to suppress HER than Fe2@and Co2@GDY, which may result from the modulated d state electronic structure due to the synergy effect of the heteronuclear atoms in the DACs. Our work not only suggests that FeCo@and NiCo@GDY hold great promises as efficient, low-cost, and stable DACs for NRR, but also further provides a strategy, i.e. alloying the atomic metal catalysts, to improve the NRR catalytic activity and/or selectivity.

Select

In-situ surface decoration of RuO2 nanoparticles by laser ablation for improved oxygen evolution reaction activity in both acid and alkali solutions Zongpeng Wang, Beibei Xiao, Zhiping Lin, Shijie Shen, Aijiao Xu, Zexin Du, Yuchao Chen, Wenwu Zhong 2021, 54(3): 510-518.  DOI: 10.1016/j.jechem.2020.06.042 Abstract ( 5 )   PDF (10336KB) ( 2 )   Improving the OER activity of noble metal-based materials is of profound importance to minimize the usage of noble metals and lower the cost. Here, we report considerable improvement on the catalytic activity of RuO2 particles for OER in both alkali and acid environments. The RuO2 nanoparticles were treated with a method of pulse laser ablation. Numerous Ru and RuO2 clusters were generated at the surface of RuO2 nanoparticles after the laser ablation, forming a lychee-shaped morphology. The larger pulse energy RuO2 nanoparticles are treated with, the better the OER activity can be. DFT calculations shows that the surface tension induced by the lychee-shaped morphology benefits the OER performance. Our best sample gives an overpotential of 172 mV (at 10 mA cm-2) and a Tafel slope of 53.5 mV dec-1 in KOH, while an overpotential of 219 mV and a Tafel slope of 44.9 mV dec-1 in H2SO4, which are of top-class results. This work may inspire a new way to develop high-performance electrocatalysts for OER.

Select

Molten salt as ultrastrong polar solvent enables the most straightforward pyrolysis towards highly efficient and stable single-atom electrocatalyst Nannan Li, Wei Liu, Chao Zhu, Ce Hao, Jingya Guo, Hongyu Jing, Jinwen Hu, Cuncun Xin, Danyang Wu, Yantao Shi 2021, 54(3): 519-527.  DOI: 10.1016/j.jechem.2020.06.021 Abstract ( 3 )   PDF (7876KB) ( 1 )   Currently, pyrolysis as the most widely used method still has some key issues not well resolved for synthesis of carbon-supported single-atom catalysts (C-SACs), e.g., the sintering of metal atoms at high temperature as well as the high cost and complicated preparations of precursors. In this report, molten salts are demonstrated to be marvellous medium for preparation of C-SACs by pyrolysis of small molecular precursors (ionic liquid). The ultrastrong polarity on one hand establishes robust interaction with precursor and enables better carbonization, resulting in largely enhanced yield. On the other hand, the aggregation of metal atoms is effectively refrained while no nanoparticle or cluster is formed. By this strategy, a C-SAC with atomically dispersed Fe-N4 sites and a high specific area over 2000 m2 g-1 is obtained, which illustrates high ORR activity in both acid and alkaline media. Moreover, this SAC exhibits superior methanol tolerance and stability after acid soaking at 85 °C for 48 h. It is believed that the molten-salts-assisted pyrolysis can be developed into a routine strategy as it not only can largely simply the synthesis of C-SACs, but also can be extended to prepare other types of SACs.

Select

2,5-Furandicarboxylic acid production via catalytic oxidation of 5-hydroxymethylfurfural: Catalysts, processes and reaction mechanism Chunlin Chen, Lingchen Wang, Bin Zhu, Zhenqiang Zhou, Soliman I. El-Hout, Jie Yang, Jian Zhang 2021, 54(3): 528-554.  DOI: 10.1016/j.jechem.2020.05.068 Abstract ( 7 )   PDF (17842KB) ( 2 )   Biomass conversion to value-added chemicals has received tremendous attention for solving global warming issues and fossil fuel depletion. 5-Hydroxymethylfurfural (HMF) is a key bio-based platform molecule to produce many useful organic chemicals by oxidation, hydrogenation, polymerization, and ring-opening reactions. Among all derivatives, the oxidation product 2,5-furandicarboxylic acid (FDCA) is a promising alternative to petroleum-based terephthalic acid for the synthesis of biodegradable plastics. This review analytically discusses the recent progress in the thermocatalytic, electrocatalytic, and photocatalytic oxidation of HMF into FDCA, including catalyst screening, synthesis processes, and reaction mechanism. Rapid fundamental advances may be possible in non-precious metal and metal-free catalysts that are highly efficient under the base-free conditions, and external field-assisted processes like electrochemical or photoelectrochemical cells.

Select

Nitrogen-rich metal-organic framework mediated Cu-N-C composite catalysts for the electrochemical reduction of CO2 Si-Min Cao, Hua-Bo Chen, Bao-Xia Dong, Qiu-Hui Zheng, Yan-Xia Ding, Meng-Jie Liu, She-Liang Qian, Yun-Lei Teng, Zong-Wei Li, Wen-Long Liu 2021, 54(3): 555-563.  DOI: 10.1016/j.jechem.2020.06.038 Abstract ( 9 )   PDF (3921KB) ( 1 )   Cu-based MOFs, i.e., HKUST-1, etc., have been pertinently chosen as the pristine materials for CO2ER due to the unique ability of copper for generation hydrocarbon fuel. However, the limited conductivity and stability become the stumbling-block that prevents the development of it. The exploring of MOFs-derived M-C materials starts a new chapter for the MOFs precursors, which provides a remarkable electronic connection between carbon matrix and metals/metal oxides. N-doped M-N-C with extensive M-N sites scattering into the carbon matrix are more popular because of their impressive contribution to catalytic activity and specific product selectivity. Nevertheless, Cu-N-C system remained undeveloped up to now. The lack of ideal precursor, the sensitivity of Cu to be oxidized, and the difficulties in the synthesis of small size Cu nanoparticles are thus known as the main barriers to the development of Cu-N-C electrocatalysts. Herein, a nitrogen-rich Cu-BTT MOF is employed for the derivation of N-doped Cu-N-CT composite electrocatalysts by the pyrolyze method. High-temperature pyrolysis product of Cu-N-C1100 exhibits the best catalytic activity for productions of CO (-0.6 V vs. RHE, jCO = 0.4 mA/cm2) and HCOOH (-0.9 V vs. RHE, jHCOOH = 1.4 mA/cm2).

Select

An advanced low-cost cathode composed of graphene-coated Na2.4Fe1.8(SO4)3 nanograins in a 3D graphene network for ultra-stable sodium storage Yongjin Fang, Qi Liu, Xiangming Feng, Weihua Chen, Xinping Ai, Liguang Wang, Liang Wang, Zhiyuan Ma, Yang Ren, Hanxi Yang, Yuliang Cao 2021, 54(3): 564-570.  DOI: 10.1016/j.jechem.2020.06.020 Abstract ( 9 )   PDF (7313KB) ( 7 )   Iron-based electrodes have attracted great attention for sodium storage because of the distinct cost effectiveness. However, exploring suitable iron-based electrodes with high power density and long duration remains a big challenge. Herein, a spray-drying strategy is adopted to construct graphene-coated Na2.4Fe1.8(SO4)3 nanograins in a 3D graphene microsphere network. The unique structural and compositional advantages endow these electrodes to exhibit outstanding electrochemical properties with remarkable rate performance and long cycle life. Mechanism analyses further explain the outstanding electrochemical properties from the structural aspect.

Select

Facile fabrication of MoP nanodots embedded in porous carbon as excellent anode material for potassium-ion batteries Zhanheng Yan, Zhongyuan Huang, Haihui Zhou, Xinxin Yang, Songlin Li, Wenlong Zhang, Fei Wang, Yafei Kuang 2021, 54(3): 571-578.  DOI: 10.1016/j.jechem.2020.06.037 Abstract ( 5 )   PDF (4424KB) ( 2 )   Molybdenum phosphide (MoP), owing to its abundant reserve and high theoretical capacity, is regarded as a promising anode material for potassium-ion batteries. However, it still suffers from the problems of acute volume expansion and weak diffusion kinetics. This study reports a simple method to synthesize a composite of molybdenum phosphide and porous carbon (MoP@PC) through simple mixing and annealing treatment. In the MoP@PC, lots of MoP nanodots with an average diameter of about 4 nm uniformly embedded in the petal-like porous carbon. The MoP@PC shows reversible capacities of 330 mAh g-1 at 100 mA g-1 after 100 cycles, and ultra-long cycling stability with a capacity of 240 mAh g-1 after 1000 cycles at 1 A g-1 and 161 mAh g-1 after 1000 cycles at 5 A g-1. The structure of MoP@PC after charging-discharging cycles is also investigated by high resolution transmission electron microscope (HRTEM) and the result shows that MoP can still maintain the nanodot morphology without any agglomeration after 1000 cycles at 5 A g-1. The storage mechanism of potassium ions was studied as well, which reveals that MoP and potassium ion have a conversion reaction.

Select

Solid phase microwave-assisted fabrication of Fe-doped ZIF-8 for single-atom Fe-N-C electrocatalysts on oxygen reduction Xinlong Xu, Xiaoming Zhang, Zhangxun Xia, Ruili Sun, Huanqiao Li, Junhu Wang, Shansheng Yu, Suli Wang, Gongquan Sun 2021, 54(3): 579-586.  DOI: 10.1016/j.jechem.2020.06.046 Abstract ( 5 )   PDF (7520KB) ( 5 )   Fe-N-C endowed with inexpensiveness, high activity, and excellent anti-poisoning power have emerged as promising candidate catalysts for oxygen reduction reaction (ORR). Single-atom Fe-N-C electrocatalysts derived from Fe-doped ZIF-8 represent the top-level ORR performance. However, the current fabrication of Fe-doped ZIF-8 relies on heavy consumption of time, energy, cost and organic solvents. Herein, we develop a rapid and solvent-free method to produce Fe-doped ZIF-8 under microwave irradiation, which can be easily amplified in combination with ball-milling. After rational pyrolysis, Fe-N-C catalysts with atomic FeN4 sites well dispersed on the hierarchically porous carbon matrix are obtained, which exhibit exceptional ORR performance with a half-wave potential of 0.782 V (vs. reversible hydrogen electrode (RHE)) and brilliant methanol tolerance. The assembled direct methanol fuel cells (DMFCs) endow a peak power density of 61 mW cm-2 and extraordinary stability, highlighting the application perspective of this strategy.

Select

2D polyaniline with exchangeable interlayer fluid for fast and stable volumetric dual ion storage Xiaochen Yang, Jiaxing Liang, Aditya Rawal, Kefeng Xiao, Yuan Pu, Xiao Li Zhang, Ruopian Fang, Da-Wei Wang 2021, 54(3): 587-594.  DOI: 10.1016/j.jechem.2020.06.015 Abstract ( 5 )   PDF (6582KB) ( 2 )   Two-dimensional (2D) layered materials are widely applied in energy devices including lithium-ion battery and supercapacitor due to their unique properties, such as tunable interlayer structure, numerous active sites, large aspect ratio versatile interlayer chemistry. In this work, 2D layered tungstate acid-linked polyaniline (TALP) presented a fluid-in-solid structure, which allowed facile exchange of the interlayer fluid from moisture to conventional Li+ containing electrolyte. With fast and stable dual ion storage (Li+ and PF6-), TALP demonstrates high-rate volumetric capacity (39 mAh cm-3 at 2000 mA g-1) and good stability (2000 cycles at 200 mA g-1) within the working potential window of 1.5-4.5 V versus Li+/Li.

Select

Rational design of hollow oxygen deficiency-enriched NiFe2O4@N/rGO as bifunctional electrocatalysts for overall water splitting Lei Cao, Zhenhuan Li, Kunmei Su, Maliang Zhang, Bowen Cheng 2021, 54(3): 595-603.  DOI: 10.1016/j.jechem.2020.06.053 Abstract ( 7 )   PDF (11676KB) ( 1 )   Bimetallic metal organic framework (MOF) as a precursor to prepare catalysts with bifunctional catalytic activity of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) attracts more and more attention. Herein, hollow oxygen deficiency-enriched NiFe2O4 is synthesized by pyrolytic FeNi bimetallic MOF. The defects of rGO during carbonization can act as nucleation sites for FeNi particles. After nucleation and N doping, the FeNi particles were served as catalysts for the deposition of dissolved carbon in the defects of the N/rGO. These deposited carbon, like a bridge, connect N/rGO and hollow oxygen deficiency-enriched NiFe2O4 together, which giving full play to the advantages of N/rGO in fast electron transfer, thereby improving its catalytic activity. The resultant NiFe2O4@N/rGO-800 exhibits a low overpotential of 252 mV at 20 mA cm-2 for OER and 157 mV at 10 mA cm-2 for HER in 1 M KOH, respectively. When used as bifunctional electrodes for overall water splitting, it also shows low cell voltage of 1.60 V and 1.67 V at 10 and 20 mA cm-2, respectively.

Select

Reduced graphene oxide doping flower-like Fe7S8 nanosheets for high performance potassium ion storage Na Cheng, Xiaoyan Chen, Lushuang Zhang, Zhigang Liu 2021, 54(3): 604-611.  DOI: 10.1016/j.jechem.2020.06.043 Abstract ( 4 )   PDF (4566KB) ( 1 )   Finding easy-to-operate strategy to obtain anode material with well-designed structure and excellent electrochemical performance is necessary to promote the development of the future potassium-ion batteries (PIBs). In this work, we synthesized reduced graphene oxide doping flower-like Fe7S8 nanosheets electrode materials using one-step hydrothermal strategy. The rGO@Fe7S8 composite is composed of homogeneous Fe7S8 and reduced graphene oxide thin nanosheets. This unique structure not only promotes the penetration of electrolyte and increases the conductive of the pure Fe7S8 electrode materials, but also relieves the volume expansion of K+ during charge/discharge process. When applied this interesting anode electrode for PIBs, the rGO@Fe7S8 exhibits excellent electrochemical performance. It delivers a high reversible specific capacity of 445 mAh g-1 at 50 mA g-1, excellent rate performance (284 mAh g-1 at 500 mA g-1 and 237 mAh g-1 at 1000 mA g-1), and a high cycling stability at 100 mA g-1 (maintained 355 mAh g-1 after 300 cycles).

Select

Heterogeneous single-cluster catalysts (Mn3, Fe3, Co3, and Mo3) supported on nitrogen-doped graphene for robust electrochemical nitrogen reduction Guokui Zheng, Lei Li, Ziqi Tian, Xingwang Zhang, Liang Chen 2021, 54(3): 612-619.  DOI: 10.1016/j.jechem.2020.06.048 Abstract ( 5 )   PDF (5240KB) ( 2 )   Electrochemical nitrogen reduction reaction (NRR) is one of the most promising alternatives to the traditional Haber-Bosch process. Designing efficient electrocatalysts is still challenging. Inspired by the recent experimental and theoretical advances on single-cluster catalysts (SCCs), we systematically investigated the catalytic performance of various triple-transition-metal-atom clusters anchored on nitrogen-doped graphene for NRR through density functional theory (DFT) calculation. Among them, Mn3-N4, Fe3-N4, Co3-N4, and Mo3-N4 were screened out as electrocatalysis systems composed of non-noble metal with high activity, selectivity, stability, and feasibility. Particularly, the Co3-N4 possesses the highest activity with a limiting potential of -0.41 V through the enzymatic mechanism. The outstanding performance of Co3-N4 can be attributed to the unique electronic structure leading to strong π backdonation, which is crucial in effective N2 activation. This work not only predicts four efficient non-noble metal electrocatalysts for NRR, but also suggest the SCCs can serve as potential candidates for other important electrochemical reactions.

Select

Chlorinated polymer solar cells simultaneously enhanced by fullerene and non-fullerene ternary strategies Longzhu Liu, Pengjie Chao, Daize Mo, Feng He 2021, 54(3): 620-625.  DOI: 10.1016/j.jechem.2020.06.014 Abstract ( 6 )   PDF (2527KB) ( 2 )   To achieve efficient polymer solar cells (PSCs) with full utilization of the whole spectrum, the multi-component devices are of great importance to be deeply explored, especially for their capability of one-step fabrication. However, the research about one same binary system simultaneously derivated various multi-component PSC is still very limited. Herein, we achieved the whole constructions from one binary host to different ternary systems and even the quaternary one. The ternary strategies with fullerene acceptor, PC71BM, and non-fullerene acceptor, BT6IC-BO-4Cl, as the third component, both boosted the device efficiencies of PBT4Cl-Bz: IT-4F binary system from about 9% to comparatively beyond 11%. Despite the comparable improvement of performance, there existed other similarities and differences in two ternary strategies. In detail, the isotropic carrier transport of PC71BM which largely elevated the fill factor (FF) in the corresponding devices, while the strong absorption of BT6IC-BO-4Cl enhanced the short current density (Jsc) most. More interestingly, quaternary devices based on PBT4Cl-Bz: IT-4F: PC71BM: BT6IC-BO-4Cl could combine both advantages of fullerene and non-fullerene ternary strategies, further pumped the Jsc from 16.44 to the highest level of 19.66 mA cm-2 among all devices, eventually resulted in an optimized efficiency of 11.69%. It reveals that both fullerene and non-fullerene ternary strategies have their unique feature to elevate the device performance either by efficient isotropic carrier transport or better coverage of whole sunlight spectrum and easy tunable energy levels from organic materials. The key is how to integrate the two pathways in one system and provide a more competitive solution facing high-quality PSCs.

Select

In situ construction of Co/N/C-based heterojunction on biomass-derived hierarchical porous carbon with stable active sites using a Co-N protective strategy for high-efficiency ORR, OER and HER trifunctional electrocatalysts Xuehui Lv, Zuoxu Xiao, Haoyuan Wang, Xinlong Wang, Lulu Shan, Fuling Wang, Chuangyu Wei, Xiangjie Tang, Yanli Chen 2021, 54(3): 626-638.  DOI: 10.1016/j.jechem.2020.06.040 Abstract ( 4 )   PDF (7823KB) ( 2 )   The facile designs and fabrication of noble metal-free electrocatalysts are highly required to achieve multifunctional catalytic activity with excellent stability in Zn-air batteries, fuel cells and water splitting systems. Herein, a heterostructure engineering is applied to construct the high performance Co, N-containing carbon-based multifunctional electrocatalysts with the feature of isotype (i.e. n-n type Co2N0.67-BHPC) and anisotype (i.e. p-n type Co2O3-BHPC) heterojunctions for ORR, OER and HER. The n-n type Co2N0.67-BHPC, in which biomass (e.g. mushroom)-derived hierarchical porous carbon (BHPC) incorporated with nonstoichiometric active species Co2N0.67, is fabricated by using an in situ protective strategy of macrocyclic central Co-N4 from CoTPP (5,10,15,20-tetrakis(phenyl) porphyrinato cobalt) precursor through the intermolecular π-π interactions between CoTPP and its metal-free analogue H2TPP. Meanwhile, an unprotected strategy of macrocyclic central Co-N4 from CoTPP can afford the anisotype Co2O3-BHPC p-n heterojunction. The as-prepared n-n type Co2N0.67-BHPC heterojunction exhibited a higher density of Co-based active sites with outstanding stability and more efficient charge transfer at the isotype heterojunction interface in comparison with p-n type Co2O3-BHPC heterojunction. Consequently, for ORR, Co2N0.67-BHPC exhibits the more positive onset and half-wave potentials of 0.93 and 0.86 V vs. RHE, respectively, superior to those of the commercial 20 wt% Pt/C and most of Co-based catalysts reported so far. To drive a current density of 10 mA cm-2, Co2N0.67-BHPC also shows the lower overpotentials of 0.34 and 0.21 V vs. RHE for OER and HER, respectively. Furthermore, the Zn-air battery equipped with Co2N0.67-BHPC displays higher maximum power density (109 mW cm-2) and charge-discharge cycle stability. Interestingly, the anisotype heterojunction Co2O3-BHPC as trifunctional electrocatalyst reveals evidently photoelectrochemical enhancement compared with the photostable Co2N0.67-BHPC. That is to say, isotype heterojunction material (n-n type Co2N0.67-BHPC) is equipped with better electrocatalytic performance than anisotype one (p-n type Co2O3-BHPC), but the opposite is true in photoelectrochemical catalysis. Meanwhile, the possible mechanism is proposed based on the energy band structures of the Co2N0.67-BHPC and Co2O3-BHPC and the cocatalyst effects. The present work provides much more possibilities to tune the electrocatalytic and photoelectrochemical properties of catalysts through a facile combination of heterostructure engineering protocol and macrocyclic central metal protective strategy.

Select

Non-stoichiometric CoS1.097 nanoparticles prepared from CoAl-layered double hydroxide and MOF template as cathode materials for aluminum-ion batteries Ruiyuan Zhuang, Guo Miao, Zengliang Huang, Qianqian Zhang, Jian-Chun Wu, Jianhong Yang 2021, 54(3): 639-643.  DOI: 10.1016/j.jechem.2020.06.047 Abstract ( 6 )   PDF (7291KB) ( 2 )

Select

High-performance all-solid-state polymer electrolyte with fast conductivity pathway formed by hierarchical structure polyamide 6 nanofiber for lithium metal battery Lu Gao, Jianxin Li, Jingge Ju, Bowen Cheng, Weimin Kang, Nanping Deng 2021, 54(3): 644-654.  DOI: 10.1016/j.jechem.2020.06.035 Abstract ( 4 )   PDF (4550KB) ( 2 )   The utilization of all-solid-state electrolytes is considered to be an effective way to enhance the safety performance of lithium metal batteries. However, the low ionic conductivity and poor interface compatibility greatly restrict the development of all-solid-state battery. In this study, a composite electrolyte combining the electrospun polyamide 6 (PA6) nanofiber membrane with hierarchical structure and the polyethylene oxide (PEO) polymer is investigated. The introduction of PA6 nanofiber membrane can effectively reduce the crystallinity of the polymer, so that the ionic conductivity of the electrolyte can be enhanced. Moreover, it is found that the presence of finely branched fibers in the hierarchical structure PA6 membrane allows the polar functional groups (C=O and N-H bonds) to be fully exposed, which provides sufficient functional sites for lithium ion transport and helps to regulate the uniform deposition of lithium metal. Moreover, the hierarchical structure can enhance the mechanical strength (9.2 MPa) of the electrolyte, thereby effectively improving the safety and cycle stability of the battery. The prepared Li/Li symmetric battery can be stably cycled for 1500 h under 0.3 mA cm-2 and 60 °C. This study demonstrates that the prepared electrolyte has excellent application prospects in the next generation all-solid-state lithium metal batteries.

Select

Promise and challenge of vanadium-based cathodes for aqueous zinc-ion batteries Yaru Zhang, Aibing Chen, Jie Sun 2021, 54(3): 655-667.  DOI: 10.1016/j.jechem.2020.06.013 Abstract ( 3 )   PDF (6538KB) ( 2 )   Aqueous zinc-ion batteries (ZIBs) have got wide attention with the increasing demands for energy resource recently. It has a number of merits compared with lithium-ion batteries, such as enhanced safety, low cost and environmental friendliness. Vanadium-based materials have been developed to serve as the cathodes of ZIBs for many years. But there are also some challenges to construct high performance ZIBs in the future. Herein, we reviewed the research progress of vanadium-based cathodes and discussed the energy storage mechanisms in ZIBs. In addition, we summarized the major challenges faced by vanadium-based cathodes and the corresponding ways to improve electrochemical performance of ZIBs. Finally, some excellent vanadium-based cathodes are summarized to pave the way for future research in ZIBs.

Select

Selective adsorption-involved formation of NMC532/PANI microparticles with high ageing resistance and improved electrochemical performance Mingchuan Shao, Changshuo Shang, Fengxiang Zhang, Zhen Xu, Wei Hu, Qingqing Lu, Ligang Gai 2021, 54(3): 668-679.  DOI: 10.1016/j.jechem.2020.07.001 Abstract ( 6 )   PDF (7990KB) ( 2 )   Surface modification offers an alternative strategy to improve both ageing resistance and electrochemical performance of cathode materials for lithium-ion batteries. From the viewpoint of real application, surface modification of the cathode materials should be designed with scientificity, effectiveness, low cost, less Li+ leaching, and remained tap density. In this contribution, a selective adsorption-involved in-situ growth of polyaniline (PANI) nanoparticles on LiNi0.5Mn0.3Co0.2O2 (NMC532) has been designed through a room-temperature-and-pressure chemical vapor deposition technique. The selective growth of PANI on NMC532 is based on theoretical computation results that multivalent Ni, Mn, and Co are capable of specifically conjugating and activating aniline molecules and, hence, initiating in-situ oxidation polymerization. With only trace amount of aniline monomer, the resulting PANI nanoparticles-inlaid NMC532 microparticles can endure four-month ageing in ambient atmosphere and exhibit improved electrochemical performance at both room temperature and 55 °C, compared with pristine NMC532. The improved electrochemical performance of NMC532/PANI is attributed to the enhanced structural stability of NMC532 and inhibited side reactions related to Li2CO3 formation, PVDF degradation, electrolyte decomposition, and transition-metal dissolution, owing to PANI modification.

Select

Towards high-performance anodes: Design and construction of cobalt-based sulfide materials for sodium-ion batteries Baole Guan, Si-Yu Qi, Ying Li, Ting Sun, Yan-Guo Liu, Ting-Feng Yi 2021, 54(3): 680-698.  DOI: 10.1016/j.jechem.2020.06.005 Abstract ( 8 )   PDF (22101KB) ( 3 )   Sodium-ion batteries are increasingly becoming important in the energy storage field owing to their low cost and high natural abundance of sodium. Cobalt-based sulfide materials have been extensively studied as anode materials owing to their remarkable Na storage capability. Nevertheless, the application of cobalt-based sulfides is hampered by their serious capacity degradation and unsatisfactory cycling stability due to severe structural changes during cycling. Therefore, it is important to comprehensively summarize advances in the understanding and modification of cobalt-based sulfides from various perspectives. In the present review, recent advances on various cobalt-based sulfides, such as CoS, CoS2, Co3S4, Co9S8, NiCo2S4, CuCo2S4, and SnCoS4, are outlined with particular attention paid to strategies that improve their sodium storage performance. First, the mechanisms of charge storage are introduced. Subsequently, the key barriers to their extensive application and corresponding strategies for designing high-performance cobalt-based sulfide anode materials are discussed. Finally, key developments are summarized and future research directions are proposed based on recent advancements, aiming to offer possible fascinating strategies for the future promotion of cobalt-based sulfides as anode materials applied in sodium-ion batteries.

Select

Synergy of a hierarchical porous morphology and anionic defects of nanosized Li4Ti5O12 toward a high-rate and large-capacity lithium-ion battery Yanan Li, Qianlin Chen, Qiangqiang Meng, Shulai Lei, Fangxiang Song, Jingbo Ma 2021, 54(3): 699-711.  DOI: 10.1016/j.jechem.2020.06.049 Abstract ( 4 )   PDF (13612KB) ( 2 )   Exploring electrode materials with a high volumetric energy density and high rate capability remains of a great challenge for nanosized-Li4Ti5O12 (LTO) batteries. Here, hierarchical porous Ti3+-C-N-Br co-doped LTO (LTOCPB-CC) is synthesized using carboxyl-grafted nanocarbon (CC) and cetylpyridinium bromide (CPB) as combined structure-directing agents. Ti4+-O-CPB/Li+-CC is designed as a new molecular chelate, in which CPB and CC promote the uniform mixing of Li+ and Ti4+ and control the morphology of TiO2 and the final product. The defects (oxygen vacancies and ion dopants) formed during the annealing process increase the electron/hole concentration and reduce the band gap, both of which enhance the n-type electron modification of LTO. As-prepared LTOCPB-CC has a large specific surface area and high tap density, as well as a high electronic conductivity (2.84 × 10-4 S cm-1) and ionic conductivity (3.82 × 10-12 cm2 s-1), which are responsible for its excellent rate capability (157.7 mA h g-1 at 20 C) and stable long-term cycling performance (0.008% fade per cycle after 1000 cycles at 20 C).

Select

Recent advances in energy storage mechanism of aqueous zinc-ion batteries Duo Chen, Mengjie Lu, Dong Cai, Hang Yang, Wei Han 2021, 54(3): 712-726.  DOI: 10.1016/j.jechem.2020.06.016 Abstract ( 5 )   PDF (17330KB) ( 1 )   Aqueous rechargeable zinc-ion batteries (ZIBs) have recently attracted increasing research interest due to their unparalleled safety, fantastic cost competitiveness and promising capacity advantages compared with the commercial lithium ion batteries. However, the disputed energy storage mechanism has been a confusing issue restraining the development of ZIBs. Although a lot of efforts have been dedicated to the exploration in battery chemistry, a comprehensive review that focuses on summarizing the energy storage mechanisms of ZIBs is needed. Herein, the energy storage mechanisms of aqueous rechargeable ZIBs are systematically reviewed in detail and summarized as four types, which are traditional Zn2+ insertion chemistry, dual ions co-insertion, chemical conversion reaction and coordination reaction of Zn2+ with organic cathodes. Furthermore, the promising exploration directions and rational prospects are also proposed in this review.

Select

N-doped porous carbon nanofibers sheathed pumpkin-like Si/C composites as free-standing anodes for lithium-ion batteries Yanfei Zeng, Yudai Huang, Niantao Liu, Xingchao Wang, Yue Zhang, Yong Guo, Hong-Hui Wu, Huixin Chen, Xincun Tang, Qiaobao Zhang 2021, 54(3): 727-735.  DOI: 10.1016/j.jechem.2020.06.022 Abstract ( 9 )   PDF (8942KB) ( 2 )   Dramatic capacity fading and poor rate performance are two main obstacles that severely hamper the widespread application of the Si anode owing to its large volume variation during cycling and low intrinsic electrical conductivity. To mitigate these issues, free-standing N-doped porous carbon nanofibers sheathed pumpkin-like Si/C composites (Si/C-ZIF-8/CNFs) are designed and synthesized by electrospinning and carbonization methods, which present greatly enhanced electrochemical properties for lithium-ion battery anodes. This particular structure alleviates the volume variation, promotes the formation of stable solid electrolyte interphase (SEI) film, and improves the electrical conductivity. As a result, the as-obtained free-standing Si/C-ZIF-8/CNFs electrode delivers a high reversible capacity of 945.5 mA h g-1 at 0.2 A g-1 with a capacity retention of 64% for 150 cycles, and exhibits a reversible capacity of 538.6 mA h g-1 at 0.5 A g-1 over 500 cycles. Moreover, the full cell composed of a free-standing Si/C-ZIF-8/CNFs anode and commercial LiNi1/3Co1/3Mn1/3O2 (NCM) cathode shows a capacity of 63.4 mA h g-1 after 100 cycles at 0.2 C, which corresponds to a capacity retention of 60%. This rational design could provide a new path for the development of high-performance Si-based anodes.

Select

High-temperature electrocatalysis and key materials in solid oxide electrolysis cells Lingting Ye, Kui Xie 2021, 54(3): 736-745.  DOI: 10.1016/j.jechem.2020.06.050 Abstract ( 7 )   PDF (3950KB) ( 4 )   Solid oxide electrolysis cells (SOECs) can convert electricity to chemicals with high efficiency at ~600-900 °C, and have attracted widespread attention in renewable energy conversion and storage. SOECs operate in the inverse mode of solid oxide fuel cells (SOFCs) and therefore inherit most of the advantages of SOFC materials and energy conversion processes. However, the external bias that drives the electrochemical process will strongly change the chemical environments in both in the cathode and anode, therefore necessitating careful reconsideration of key materials and electrocatalysis processes. More importantly, SOECs provide a unique advantage of electrothermal catalysis, especially in converting stable low-carbon alkanes such as methane to ethylene with high selectivity. Here, we review the state-of-the-art of SOEC research progress in electrothermal catalysis and key materials and provide a future perspective.

Select

Ultrathin NixCoy-silicate nanosheets natively anchored on CNTs films for flexible lithium ion batteries Wenlei Guo, Wenping Si, Tao Zhang, Yonghuan Han, Lei Wang, Ziyue Zhou, Pengyi Lu, Feng Hou, Ji Liang 2021, 54(3): 746-753.  DOI: 10.1016/j.jechem.2020.06.026 Abstract ( 4 )   PDF (9082KB) ( 1 )   The rapid development of portable and wearable electronics has called for novel flexible electrodes with superior performance. The development of flexible electrode materials with excellent mechanical and electrochemical properties has become one of the key factors for this goal. Here, a NixCoy-silicate@CNTs film is developed as a flexible anode for lithium ion batteries (LIBs). On this film, NixCoy-silicate nanosheets are firmly and intimately anchored on the surface of CNTs, which have a 3D network structure and link the adjacent nanosheets together. Benefitted from this, the composite film is not only sufficient to withstand various deformations due to its excellent flexibility but also has excellent electrochemical properties, in terms of high reversible capacity of 1047 mAh g-1 at 0.1 A g-1 as well as a high rate and cycling performance (capacity retention up to 78.13% after 140 cycles). The pouch-type full flexible LIB using this material can stably operate under various bending conditions, showing the great potential of this 3D NixCoy-silicate@CNTs film for flexible energy storage devices with high durability.

Select

Self-supported hierarchical porous Li4Ti5O12/carbon arrays for boosted lithium ion storage Jun Liu, Aixiang Wei, Guoxiang Pan, Shenghui Shen, Zhiming Xiao, Yu Zhao, Xinhui Xia 2021, 54(3): 754-760.  DOI: 10.1016/j.jechem.2020.06.017 Abstract ( 3 )   PDF (6068KB) ( 1 )   The development of fast rechargeable lithium ion batteries (LIBs) is highly dependent on the innovation of advanced high-power electrode materials. In this work, for the first time, we report a sacrificial NiO arrays template method for controllable synthesis of self-supported hierarchical porous Li4Ti5O12/C (LTO/C) nanoflakes arrays, for use as fast rechargeable anodes for LIBs. The ultrathin (2-3 nm) carbon layer was uniformly coated on the LTO forming arrays architecture. The hierarchical porous LTO/C nanoflakes consisted of primary cross-linked nanoparticles of 50-100 nm and showed large porosity. Because of the enhanced electrical conductivity and accelerated ion transfer channels, the well-designed binder-free porous LTO/C nanoflakes arrays exhibited notable high-rate lithium ion storage performance with smaller polarization, better electrochemical reactivity, higher specific capacity (157 mAh g-1 at the current density of 20C) and improved long-term cycling life (96.2% after 6000 cycles at 20 C), superior to the unmodified porous LTO arrays counterpart (126 mAh g-1 at 20C and 88.0% after 6000 cycles at 20 C). Our work provides a new template for the construction of high-performance high-rate electrodes for electrochemical energy storage.

Select

Two flowers per seed: Derivatives of CoG@F127/GO with enhanced catalytic performance of overall water splitting Yue Han, Chen Qian, Huayu Wu, Xing Chen, Xue Wu, Wei He, Hui Yan, Guisheng Li, Guowang Diao, Ming Chen 2021, 54(3): 761-769.  DOI: 10.1016/j.jechem.2020.06.051 Abstract ( 4 )   PDF (7563KB) ( 2 )   In this work, cobalt glycerate (CoG@F127) nanosheets grown on the surface of graphene oxide (GO), i.e. CoG@F127/GO, have been synthesized with the assistance of nonionic surfactant Pluronic F127 via a hydrothermal method. After calcination, CoG@F127/GO is transformed into one derivative, Co nanoparticles coated with a trace amount of carbon (Co-C) on GO (Co-C/GO). The Co nanoparticles consist of an atypical core-shell structure, in which the core and the shell are both Co. Co-C anchored on GO can avoid the nanoparticles aggregation and expose more active sites for hydrogen evolution reaction (HER) to significantly improve the catalyst activity of HER. CoG@F127/GO is phosphatized to form the other derivate, cobalt pyrophosphate coated with a small amount of carbon (Co2P2O7-C) on GO (Co2P2O7-C/GO). Co2P2O7-C/GO composite owns a large electrochemical active surface area (ECSA) and fast rate towards oxygen evolution reaction (OER). Furthermore, the two derivatives of CoG@F127/GO, i.e. Co-C/GO and Co2P2O7-C/GO as twin flowers, are assembled into an overall water splitting electrolytic cell with a cell voltage of 1.56 V to deliver a current density of 10 mA cm-2.

Select

Recent advances in metal halide perovskite photocatalysts: Properties, synthesis and applications Jin Wang, Jiale Liu, Zhonglin Du, Zhengquan Li 2021, 54(3): 770-785.  DOI: 10.1016/j.jechem.2020.06.024 Abstract ( 6 )   PDF (5640KB) ( 2 )   As a class of new emerged semiconductors, MHPs exhibit many excellent photoelectronic properties, which are superior to most conventional semiconductor nanocrystals (NCs). Particularly, MHPs have received extensive attention and brought new opportunities for the development of photocatalysis. Over the past few years, numerous efforts have been made to design and prepare MHP-based materials for a wide range of applications in photocatalysis, ranging from photocatalytic H2 generation, photocatalytic CO2 reduction, photocatalytic organic synthesis and pollutant degradation. In this review, recent advances in the development of MHP-based materials are summarized from the standpoint of photocatalysis. A brief outlook of this field has been proposed to point out some important challenges and possible solutions. This review suggests that the new family of MHP photocatalysts provide a new paradigm in efficient artificial photosynthesis.

Select

Revealing the correlation between structure evolution and electrochemical performance of high-voltage lithium cobalt oxide Jiajia Wan, Jianping Zhu, Yuxuan Xiang, Guiming Zhong, Xiangsi Liu, Yixiao Li, Kelvin H.L. Zhang, Chaoyu Hong, Jianming Zheng, Kai Wang, Yong Yang 2021, 54(3): 786-794.  DOI: 10.1016/j.jechem.2020.06.027 Abstract ( 7 )   PDF (8508KB) ( 4 )   Lithium cobalt oxide (LCO) is the dominating cathode materials for lithium-ion batteries (LIBs) deployed in consumer electronic devices for its superior volumetric energy density and electrochemical performances. The constantly increasing demands of higher energy density urge to develop high-voltage LCO via a variety of strategies. However, the corresponding modification mechanism, especially the influence of the long- and short-range structural transitions at high-voltage on electrochemical performance, is still not well understood and needs further exploration. Based on ss-NMR, in-situ X-ray diffraction, and electrochemical performance results, it is revealed that the H3 to H1-3 phase transition dictates the structural reversibility and stability of LCO, thereby determining the electrochemical performance. The introduction of La and Al ions could postpone the appearance of H1-3 phase and induce various types of local environments to alleviate the volume variation at the atomic level, leading to better reversibility of the H1-3 phase and smaller lattice strain, and significantly improved cycle performance. Such a comprehensive long-range, local, and electronic structure characterization enables an in-depth understanding of the structural evolution of LCO, providing a guiding principle for developing high-voltage LCO for high energy density LIBs.

Select

Two dimensional nanocarbons from biomass and biological molecules: Synthetic strategies and energy related applications Baobing Huang, Yuchuan Liu, Zailai Xie 2021, 54(3): 795-814.  DOI: 10.1016/j.jechem.2020.06.033 Abstract ( 3 )   PDF (14533KB) ( 1 )   Two-dimensional (2D) carbon materials with ultrathin thickness, large lateral size, large surface area, accessible active sites and unique physical-chemical properties have been proven to be attractive electrode materials or catalysts for high-efficient energy storage and conversion materials. However, the conventional synthesis method for 2D carbon materials heavily depends on fossil-based feedstocks and goes through harsh conditions (e.g., chemical vapor deposition), which are unsustainable and costly. Besides, the top-down method needs to use massive strong acids/oxidants, which is environmentally-unfriendly. Therefore, it is necessary to commit to seek green, sustainable and cost-effective approach for the synthesis of 2D carbon materials. As of now, biomass or biological molecules as carbon-rich resources have been viewed as a promising candidate for the 2D carbon material preparation owing to its abundance, renewability, nontoxicity and low-cost. Especially for nucleobases, as an emerging molecule have been shown great advantages for the construction of 2D materials guided by its multiple hydrogen-bonding interaction. Recently, our group have proposed a rather innovative strategy to produce 2D carbon materials by carbonization of nucleobases which has relatively high electrode potentials. These nucleobases can form planar network structure through hydrogen bonding interaction. Such hydrogen-bonding can be stable at relatively high temperature, which confines C-C or C-N polymerization in a 2D plane. As a result, direct carbonization of nucleobases enables the formation of 2D carbon with highly sp2-conjugated and feature of heteroatom doping. This review systematically summarizes the recent development of the strategies to synthesize 2D sustainable carbon materials from biomass and biological molecules. The corresponding electrochemical applications such as lithium ion batteries, supercapacitors and fuel cell are selectively presented. At the end, the summary and future perspectives in this important field are provided to inspire further exploration.

Select

Switching O-O bond formation mechanism between WNA and I2M pathways by modifying the Ru-bda backbone ligands of water-oxidation catalysts Biaobiao Zhang, Shaoqi Zhan, Tianqi Liu, Linqin Wang, A. Ken Inge, Lele Duan, Brian J.J. Timmer, Oleksandr Kravchenko, Fei Li, Mårten S.G. Ahlquist, Licheng Sun 2021, 54(3): 815-821.  DOI: 10.1016/j.jechem.2020.06.036 Abstract ( 8 )   PDF (2090KB) ( 4 )   Understanding the seven coordination and O-O coupling pathway of the distinguished Ru-bda catalysts is essential for the development of next generation efficient water-oxidation catalysts based on earth-abundant metals. This work reports the synthesis, characterization and catalytic properties of a monomeric ruthenium catalyst Ru-bnda (H2bnda = 2,2′-bi(nicotinic acid)-6,6′-dicarboxylic acid) featuring steric hindrance and enhanced hydrophilicity on the backbone. Combining experimental evidence with systematic density functional theory calculations on the Ru-bnda and related catalysts Ru-bda (H2bda = 2,2ʹ-bipyridine-6,6ʹ-dicarboxylic acid), Ru-pda (H2pda = 1,10-phenanthroline-2,9-dicarboxylic acid), and Ru-biqa (H2biqa = (1,1ʹ-biisoquinoline)-3,3ʹ-dicarboxylic acid), we emphasized that seven coordination clearly determines presence of RuV=O with high spin density on the ORuV=O atom, i.e. oxo with radical properties, which is one of the necessary conditions for reacting through the O-O coupling pathway. However, an additional factor to make the condition sufficient is the favorable intermolecular face-to-face interaction for the generation of the pre-reactive [RuV=O···O=RuV], which may be significantly influenced by the secondary coordination environments. This work provides a new understanding of the structure-activity relationship of water-oxidation catalysts and their potential to adopt I2M pathway for O-O bond formation.

Select

Energy level engineering of charge selective contact and halide perovskite by modulating band offset: Mechanistic insights Yassine Raoui, Hamid Ez-Zahraouy, Samrana Kazim, Shahzada Ahmad 2021, 54(3): 822-829.  DOI: 10.1016/j.jechem.2020.06.030 Abstract ( 7 )   PDF (5990KB) ( 3 )   Mixed cation and anion based perovskites solar cells exhibited enhanced stability under outdoor conditions, however, it yielded limited power conversion efficiency when TiO2 and Spiro-OMeTAD were employed as electron and hole transport layer (ETL/HTL) respectively. The inevitable interfacial recombination of charge carriers at ETL/perovskite and perovskite/HTL interface diminished the efficiency in planar (n-i-p) perovskite solar cells. By employing computational approach for uni-dimensional device simulator, the effect of band offset on charge recombination at both interfaces was investigated. We noted that it acquired cliff structure when the conduction band minimum of the ETL was lower than that of the perovskite, and thus maximized interfacial recombination. However, if the conduction band minimum of ETL is higher than perovskite, a spike structure is formed, which improve the performance of solar cell. An optimum value of conduction band offset allows to reach performance of 25.21%, with an open circuit voltage (Voc) of 1231 mV, a current density Jsc of 24.57 mA/cm2 and a fill factor of 83.28%. Additionally, we found that beyond the optimum offset value, large spike structure could decrease the performance. With an optimized energy level of Spiro-OMeTAD and the thickness of mixed-perovskite layer performance of 26.56% can be attained. Our results demonstrate a detailed understanding about the energy level tuning between the charge selective layers and perovskite and how the improvement in PV performance can be achieved by adjusting the energy level offset.