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2022, Vol. 71, No. 8　Online: 15 August 2022

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The construction of molybdenum disulfide/cobalt selenide heterostructures @N-doped carbon for stable and high-rate sodium storage Junjie Chen, Mengyun Ling, Lingyun Wan, Chen Chen, Pei Liu, Qiuyu Zhang, Baoliang Zhang 2022, 71(8): 1-11.  DOI: 10.1016/j.jechem.2022.03.033 Abstract ( 21 )   PDF (8538KB) ( 15 )   Constructing heterostructures is an important approach to develop high-performance anode materials for sodium ion batteries (SIBs). The abundant phase interfaces provide numerous defects and active sites for rapid electron/ion transport. Herein, CoSe2 ⊂ NC@NC/MoS2 heterostructures are prepared through a multi-step reaction strategy, CoSe2 nanoparticles served as the coating shells for MoS2 cores are anchored in carbon frameworks. The core-shell structure effectively buffers the double volume expansion and inhibits the dissolution of MoS2 and CoSe2 in the electrolyte. As SIBs anodes, the heterostructure delivers a high reversible capacity of 481.6 mAh g-1 at 0.5 A g-1 after 100 cycles, superior rate capability (174.5 mAh g-1 at 20.0 A g-1), excellent long-term cycle performance (333.4 mAh g-1 after 2000 cycles at 5.0 A g-1). The DFT calculation proves that the electronic distribution of heterostructures is reconstructed with enhanced conductivity. The kinetic analysis, mechanism characterizations and full-cells tests exhibit the synergistic reaction mechanism among different components and practical application prospects. The heterostructure also shows more rapid ions diffusion kinetics than single components.

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Understanding the role of interconnecting layer on determining monolithic perovskite/organic tandem device carrier recombination properties Yue-Min Xie, Tianqi Niu, Qin Yao, Qifan Xue, Zixin Zeng, Yuanhang Cheng, Hin-Lap Yip, Yong Cao 2022, 71(8): 12-19.  DOI: 10.1016/j.jechem.2022.03.019 Abstract ( 12 )   PDF (3996KB) ( 2 )   As one of the core parts of two-terminal (2T) monolithic tandem photovoltaics, the interconnecting layers (ICLs) play a critical role in modulating the carrier transport and recombination between the sub-cells, and thus influencing the tandem device performance. Here, for the first time, the relationship between ICLs architecture and 2T monolithic perovskite/organic tandem device performance has been studied by investigating the change of ICLs composition layer thickness on the ICLs optical and electrical properties, sub-cells EQE properties, and tandem device J-V properties. It is revealed that the ability of ICLs on modulating the sub-cells carrier balance properties is strongly associated with its composited layers thickness, and the tandem device carrier balance properties can be reflected by the relative EQE intensity between the sub-cells. Finally, with a deep understanding of the mechanisms, rational design of ICLs can be made to benefit the tandem device development. Based on the optimized ICL a high PCE of 20.03% is achieved.

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In situ optical spectroscopic understanding of electrochemical passivation mechanism on sol-gel processed WO3 photoanodes Jianyong Feng, Xin Zhao, Bowei Zhang, Zhong Chen, Zhaosheng Li, Yizhong Huang 2022, 71(8): 20-28.  DOI: 10.1016/j.jechem.2022.03.023 Abstract ( 5 )   PDF (8212KB) ( 2 )   A prevailing understanding on electrochemical activation of photoelectrodes is that electrochemical treatment leads to increased charge carrier densities thereby improved photoelectrode performances. Contrary to this understanding, in this study enhanced photoactivity of WO3 photoanode upon electrochemical treatment is ascribed to an extraordinary mechanism of surface trap passivation. The associated mechanism is analyzed by in situ optical spectroscopy, using which the optical property changes of WO3 electrode during electrochemical treatment are monitored. The results suggest surface W5+ species, the origin of surface traps on WO3 photoanodes, are converted to W6+ ions by electrochemical treatment. This study demonstrates the particular ability of the electrochemical strategy to passivate surface traps of photoanodes, and also shows the advantages of in situ optical spectroscopy to investigate the real-time electronic structure variations of electrodes during electrochemical treatment.

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Dead lithium formation in lithium metal batteries: A phase field model Rui Zhang, Xin Shen, Yu-Tong Zhang, Xia-Lin Zhong, Hao-Tian Ju, Tian-Xiao Huang, Xiang Chen, Jun-Dong Zhang, Jia-Qi Huang 2022, 71(8): 29-35.  DOI: 10.1016/j.jechem.2021.12.020 Abstract ( 30 )   PDF (2572KB) ( 17 )   Lithium metal batteries are the most promising choices for next-generation high-energy-density batteries. However, there is little mechanism understanding on lithium dendrite growth during lithium plating and the dead lithium (the main component of inactive lithium) formation during lithium stripping. This work proposed a phase field model to describe the lithium stripping process with dead lithium formation. The coupling of galvanostatic conditions enables the phase field method to accurately match experimental results. The factors influencing the dead lithium formation on the increasing discharge polarization are revealed. Besides, the simulation of the battery polarization curve, the capacity loss peak, and the Coulomb efficiency is realized. This contribution affords an insightful understanding on dead lithium formation with phase field methods, which can contribute general principles on rational design of lithium metal batteries.

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Encapsulation of Fe-CoP with P, N-co-doped porous carbon matrix as a multifunctional catalyst for wide electrochemical applications Yuelong Xu, Ran Wang, Jingyue Wang, Yaru Zhang, Tifeng Jiao 2022, 71(8): 36-44.  DOI: 10.1016/j.jechem.2022.03.043 Abstract ( 4 )   PDF (11576KB) ( 2 )   Hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) serve as the most promising electrochemical processes for renewable energy. Developing multifunctional electrocatalysts with high performance for HER, OER and ORR still remains a challenge. Herein, we report a facile method to prepare P, N-co-doped porous carbon encapsulated Fe-CoP (A-Fe-CoP/CPN) electrocatalyst through freeze drying, carbonization, and KOH activation. The acquired A-Fe-CoP/CPN possesses abundant pores with large surface area, which provides sufficient defect-rich sites for HER, OER, and ORR, in alkaline or acidic electrolytes. The A-Fe-CoP/CPN shows low overpotential and good stability for HER and OER in alkaline electrolyte. Density functional theory (DFT) computations reveal that the addition of Fe greatly facilitates the rate-determining step and overall catalytic pathway for both HER and OER. A-Fe-CoP/CPN also exhibits low half-wave potential (E1/2) for ORR, which indicates an enhanced performance than that of the noble Pt/C catalyst. Zn-air battery equipped with the A-Fe-CoP/CPN catalyst exhibits a high energy density (849 mAh g-1) and a long-time stability at 5 mA cm-2. This finding not only offers a facile strategy to prepare porous carbon materials with defect-rich sites, but also provides guidance for developing multifunctional electrocatalysts for wide electrochemical reactions.

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Toward stable photoelectrochemical water splitting using NiOOH coated hierarchical nitrogen-doped ZnO-Si nanowires photoanodes Indrajit V. Bagal, Maheswari Arunachalam, Ameer Abdullah, Aadil Waseem, Mandar A. Kulkarni, SoonHyung Kang, Sang-Wan Ryu 2022, 71(8): 45-55.  DOI: 10.1016/j.jechem.2022.03.015 Abstract ( 7 )   PDF (6773KB) ( 4 )   Photoelectrochemical (PEC) water splitting is regarded as the most promising method to generate “green hydrogen”, and zinc oxide (ZnO) has been identified as one of the promising candidates for PEC water splitting owing to its straddling band alignment with the water redox level. However, its PEC performance is limited due to its wide bandgap and anticipated by photocorrosion in an aqueous medium. In this work, we present strategic improvements in the PEC water splitting performance of ZnO nanowires (NWs) by nitrogen (N)-doping along with photostability by the core-shell deposition of a NiOOH cocatalyst. Highly crystalline hierarchical ZnO NWs were fabricated on Si NWs (ZnO-Si HNWs) using a metal organic chemical vapor deposition approach. The NWs were then N-doped by annealing in an NH3 atmosphere. The N-doped ZnO-Si HNWs (N:ZnO-Si HNWs) showed enhanced visible light absorption, and suppressed recombination of the photogenerated carriers. As compared to ZnO-Si HNWs (0.045 mA cm-2 at 1.23 V vs RHE), the N:ZnO-Si HNWs (0.34 mA cm-2 at 1.23 V vs RHE) annealed in NH3 ambient for 3 h at 600 °C showed 7.5-fold enhancement in the photocurrent density. NiOOH-deposited N:ZnO-Si HNW photoanodes with a photostability of 82.21% over 20000 s showed 10.69-fold higher photocurrent density (0.48 mA cm-2 at 1.23 V vs RHE) than ZnO-Si HNWs.

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Vision for energy material design: A roadmap for integrated data-driven modeling Zhilong Wang,Yanqiang Han, Junfei Cai, An Chen, Jinjin Li 2022, 71(8): 56-62.  DOI: 10.1016/j.jechem.2022.03.052 Abstract ( 32 )   PDF (3987KB) ( 19 )

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Rational design strategies of Cu-based electrocatalysts for CO2 electroreduction to C2 products Shuo Liu, Baoshan Zhang, Lihong Zhang, Jie Sun 2022, 71(8): 63-82.  DOI: 10.1016/j.jechem.2022.03.041 Abstract ( 15 )   PDF (12225KB) ( 3 )   Electrochemical reduction of CO2 (CO2RR) to high value-added chemicals is an effective way to remove excess CO2 from the atmosphere. Due to the unique propensity of Cu for valuable hydrocarbons, Cu-based electrocatalysts are the most potential catalysts that allow the conversion of CO2 into a variety of C2 products such as ethylene and ethanol. Rational design of Cu-based catalysts can improve their directional selectivity to C2 products. Hence, in this review, we summarize the recent progress in the mechanistic studies of Cu-based catalysts on reducing CO2 to C2 products. We focus on three key strategies for efficiently enhancing electrocatalytic performance of Cu-based catalysts, including tuning electronic structure, surface structure, and coordination environment. The correlation between the structural characteristics of Cu-based catalysts and their activity and selectivity to C2 products is discussed. Finally, we discuss the challenges in the field of CO2 electroreduction to C2 products and provide the perspectives to design efficient Cu-based catalysts in the future.

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Light-induced halide segregation in perovskites with wrinkled morphology Eduardo G. Machado, Paulo E. Marchezi, Eralci M. Therézio, José Carlos Germino, Rodrigo Szostak, Caique S.de Brito, Yara G. Gobato, Ernesto C. Pereira, Michael F. Toney, Raphael Nagao, Ana Flávia Nogueira 2022, 71(8): 83-88.  DOI: 10.1016/j.jechem.2022.03.049 Abstract ( 41 )   PDF (7787KB) ( 27 )

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Synthesis of hierarchical transition metal oxyhydroxides in aqueous solution at ambient temperature and their application as OER electrocatalysts Zongkun Chen, Xingkun Wang, Sascha Keßler, Qiqi Fan, Minghua Huang, Helmut Cölfen 2022, 71(8): 89-97.  DOI: 10.1016/j.jechem.2022.02.042 Abstract ( 4 )   PDF (3666KB) ( 3 )   First-row (3d) transition metal oxyhydroxides have attracted increasing attention due to their various advantages. Although investigating the oxidation mechanism and processing such materials into hierarchical architectures are greatly desired for their further development, it remains unclear how the oxidation state change occurs, and efforts to produce hierarchical oxyhydroxides in compliance with high ecological and economic standards have progressed slowly. Here, we describe a facile one-step coprecipitation route for the preparation of hierarchical CoOOH, NiOOH and MnOOH, which involves the diffusion of NH3 originating from ammonium hydroxide solution into an aqueous solution containing metal ion salts and K2S2O8. Comprehensive characterizations by scanning electron microscope, transmission electron microscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy and in situ pH measurement demonstrated that K2S2O8 induces the oxidation state change of metal ion species after the start of hydrolysis. Meanwhile, it was found that, benefiting from the OH- concentration gradient created by the NH3 diffusion method and the suitable growth environment provided by the presence of K2S2O8 (high nucleation rate and secondary nucleation), the formation of hierarchical oxyhydroxide structures can be realized in aqueous solution at ambient temperature without the use of heat energy and additional structure-directing agents. The hierarchical CoOOH structures are performed as the electrocatalysts for the oxygen evolution reaction in alkaline media, which exhibit good activity with an overpotential of 320 mV at 10 mA cm-2 and a low Tafel slope of 59.6 mV dec-1, outperforming many congeneric electrocatalysts. Overall, our study not only provides important insights to understand the formation mechanism of hierarchical oxyhydroxides, but also opens up new opportunities for the preparation of hierarchical oxyhydroxides via a facile, green and low-cost method.

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Uneven deposition on the Al electrode under tension strain Jie He, Le Yang, Na Li, Wei-Li Song, Shuqiang Jiao, Hao-Sen Chen, Daining Fang 2022, 71(8): 98-103.  DOI: 10.1016/j.jechem.2022.03.037 Abstract ( 6 )   PDF (2706KB) ( 2 )   Structural deformation and dendrite formation, which would impact the electrochemical processes of rechargeable metal batteries, are usually observed in the high-energy density metal electrodes. Herein, we design an in-situ optical mechano-electrochemical system to study Al deposition on the Al electrode in non-aqueous Al batteries under non-uniform strain. Inhomogeneous distribution of applied strain is realized by creating an oval hole in the Al electrode. The results of the in-situ experiments suggest that the dense Al deposition, which is related to the evolution of surface morphology and increasing reactive sites, is achieved in the regions of stress concentration. The evolution of surface morphology is monitored by the in-situ tension experiments using scanning electron microscope and atomic force microscope. Besides, a qualitative mathematical model is employed to analyze the changes of the local reaction rate owing to the changed surface morphology and the cracks of oxide film under tensile stress. The results are useful to understand the Al deposition when the mechanical force is applied to the metal electrode.

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Texture engineering of mono-crystalline silicon via alcohol-free alkali solution for efficient PERC solar cells Danni Zhang, Jiawang Chen, Rui Jia, Zhibo Gao, Ke Tao, Longjie Wang, Huayun Ge, Xinpu Li, Xing Li 2022, 71(8): 104-107.  DOI: 10.1016/j.jechem.2022.03.016 Abstract ( 5 )   PDF (4245KB) ( 6 )   Control of texture structures is an effective method to reduce surface reflectivity and enhance the efficiency of solar cells. In this paper, pyramid structures are prepared on mono-crystalline silicon wafers by cyclodextrin as surfactant to slow down the etching rate in alcohol-free alkali solution. Compared with volatile alcohol surfactant (e.g. isopropanol, IPA), the cyclodextrin not only possesses a relative high boiling point (1534.4 ℃), but displays non-toxic and biodegradable properties. Furthermore, the surface morphology, average reflectivity, surface recombination of mono-crystalline silicon wafers were studied in detail. The results show that cyclodextrin can decrease the size and depth of pyramid structures, and thus a lower average reflectivity of 7.5% was obtained. In addition, ray tracing simulation was performed to calculate the photo-generated carrier concentration of PN junction with different sizes of pyramids, and the conclusion is that the carrier concentration of small pyramids is much higher than that of large pyramids. Finally, the average efficiency of large-area mono-crystalline silicon PERC solar cells fabricated by cyclodextrin surfactant was 22.69%, which was 0.43% absolutely higher than that of conventional IPA surfactant.

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Advanced flexible electrode materials and structural designs for sodium ion batteries Lina Zhao, Zhehao Qu 2022, 71(8): 108-128.  DOI: 10.1016/j.jechem.2022.03.008 Abstract ( 10 )   PDF (8324KB) ( 8 )   With the spectacular rise of wearable and portable electronics, flexible power supplying systems with robust mechanical flexibility and high energy storage performance under various mechanical deformation conditions are imperative to be needed. Sodium ion batteries (SIBs) with sustainable natural abundance, low cost and superb properties similar to equivalent lithium ion batteries (LIBs), which have shown significant potentials as energy source for flexible electronic devices. In this review, the recent advances in flexible electrode materials based on different types of conductive substrates are addressed and the strategies underlying rational design for flexible structures are highlighted, as well as their applications in flexible SIBs. The remaining key challenges in rational electrodes design are discussed, and perspectives for practical applications of flexible SIBs are proposed as general guidance for future research of high-performance flexible SIBs.

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Optimizing the electronic spin state and delocalized electron of NiCo2(OH)x/MXene composite by interface engineering and plasma boosting oxygen evolution reaction Jingyao Xu, Xia Zhong, Xiaofeng Wu, Ying Wang, Shouhua Feng 2022, 71(8): 129-140.  DOI: 10.1016/j.jechem.2022.03.025 Abstract ( 5 )   PDF (6695KB) ( 2 )   The electrocatalytic activity of transition-metal-based compounds is closely related to the electronic configuration. However, optimizing the surface electron spin state of catalysts remains a challenge. Here, we developed a spin-state and delocalized electron regulation method to optimize oxygen evolution reaction (OER) performance by in-situ growth of NiCo2(OH)x using Oswald ripening and coordinating etching process on MXene and plasma treatment. X-ray absorption spectroscopy, magnetic tests and electron paramagnetic resonance reveal that the coupling of NiCo2(OH)x and MXene can induce remarkable spin-state transition of Co3+ and transition metal ions electron delocalization, plasma treatment further optimizes the 3d orbital structure and delocalized electron density. The unique Jahn-Teller phenomenon can be brought by the intermediate spin state (t2g5eg1) of Co3+, which benefits from the partial electron occupied eg orbitals. This distinct electron configuration (t2g5eg1) with unpaired electrons leads to orbital degeneracy, that the adsorption free energy of intermediate species and conductivity were further optimized. The optimized electrocatalyst exhibits excellent OER activity with an overpotential of 268 mV at 10 mA cm-2. DFT calculations show that plasma treatment can effectively regulate the d-band center of TMs to optimize the adsorption and improve the OER activity. This approach could guide the rational design and discovery of electrocatalysts with ideal electron configurations in the future.

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Hyperbranched phthalocyanine enabling black-phase formamidinium perovskite solar cells processing and operating in humidity open air Rong Li, Jiale Ding, Xijiao Mu, Yifei Kang, Anran Wang, Weihui Bi, Yunhe Zhang, Jing Cao, Qingfeng Dong 2022, 71(8): 141-149.  DOI: 10.1016/j.jechem.2022.04.002 Abstract ( 10 )   PDF (9599KB) ( 3 )   The extreme instability of pure α-phase FAPbI3 under high humidity conditions restricts the high-throughput fabrication in unmodified air environments, resulting in poor performance of α-phase FAPbI3 perovskite devices obtained by scalable fabrication methods. Here we synthesized hyperbranched copper phthalocyanine (HCuPc) as a supramolecular additive with twisted phthalocyanine units to realize the molecular-level encapsulation at the grain boundaries through supramolecular interaction, which greatly broadened the processing window of FAPbI3 under high humidity. At the same time, unlike traditional encapsulation layer that carrier can only be collected by tunneling effect, the twisted phthalocyanine ring of HCuPc in perovskite films is more conducive to hole extraction. Finally, a record efficiency was achieved in pure FAPbI3 based inverted structured solar cell by blade-coating to the best of our knowledge, even under unmodified humid air conditions (relative humidity of 65%-85%). The best operational stability of 3D pure FAPbI3 devices can also be achieved at the same time and unencapsulated HCuPc-FAPbI3 device can even operate with negligible degradation for 100 h in the open air (RH 30%-40%).

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Dynamic active sites on plasma engraved Ni hydroxide for enhanced electro-catalytic urea oxidation Dan Li, Yuefeng Zhang, Xiaomin Zhou, Chao Huang, Ying Wen, Liangliang Liu, Qingwei Li, Yue Xu, Yuzheng Wu, Qingdong Ruan, Yinghe Ma, Fangyu Xiong, Dezhi Xiao, Pei Liu, Guomin Wang, Babak Mehrjou, Bin Wang, Hao Li, Rongsheng Chen, Hongwei Ni, Zhiyuan Zeng, Paul K. Chu 2022, 71(8): 150-158.  DOI: 10.1016/j.jechem.2022.03.040 Abstract ( 7 )   PDF (7410KB) ( 2 )   The urea oxidization reaction (UOR) is an important anodic reaction in electro-catalytic energy conversion. However, the sluggish reaction kinetics and complex catalyst transformation in electrocatalysis require activity improvement and better mechanistic understanding of the state-of-the-art Ni(OH)2 catalyst. Herein, by utilizing low-temperature argon (Ar) plasma processing, tooth-wheel Ni(OH)2 nanosheets self-supported on Ni foam (Ni(OH)2-Ar) are demonstrated to have improved UOR activity compared to conventional Ni(OH)2. The theoretical assessment confirms that the edge has a smaller cation vacancy formation energy than the basal plane, consequently explaining the structural formation. Operando and quasi-operando methods are employed to investigate the dynamic evolution of the Ni(OH)2 film in UOR. The crucial dehydrogenation products of Ni(OH)5O- intermediates are identified to be stable on the etched edge and explain the enhanced UOR in the low potential region. In addition, the dynamic active sites are monitored to elucidate the reaction mechanism in different potential ranges.

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Densely packed ultrafine SnO2 nanoparticles grown on carbon cloth for selective CO2 reduction to formate Xuewan Wang, Dan Wu, Xiaomin Kang, Jiujun Zhang, Xian-Zhu Fu, Jing-Li Luo 2022, 71(8): 159-166.  DOI: 10.1016/j.jechem.2022.03.045 Abstract ( 7 )   PDF (3668KB) ( 2 )   Electrochemical reduction of CO2 to fuels and chemicals is a viable strategy for CO2 utilization and renewable energy storage. Developing free-standing electrodes from robust and scalable electrocatalysts becomes highly desirable. Here, dense SnO2 nanoparticles are uniformly grown on three-dimensional (3D) fiber network of carbon cloth (CC) by a facile dip-coating and calcination method. Importantly, Zn modification strategy is employed to restrain the growth of long-range order of SnO2 lattices and to produce rich grain boundaries. The hybrid architecture can act as a flexible electrode for CO2-to-formate conversion, which delivers a high partial current of 18.8 mA cm-2 with a formate selectivity of 80% at a moderate cathodic potential of -0.947 V vs. RHE. The electrode exhibits remarkable stability over a 16 h continuous operation. The superior performance is attributed to the synergistic effect of ultrafine SnO2 nanoparticles with abundant active sites and 3D fiber network of the electrode for efficient mass transport and electron transfer. The sizeable electrodes hold promise for industrial applications.

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Oxygen vacancy-rich amorphous FeNi hydroxide nanoclusters as an efficient electrocatalyst for water oxidation Youhai Cao, Yang Su, Liangliang Xu, Xiaohua Yang, Zhongkang Han, Rui Cao, Gao Li 2022, 71(8): 167-173.  DOI: 10.1016/j.jechem.2022.03.044 Abstract ( 15 )   PDF (2864KB) ( 8 )   In this work, a one-pot strategy is presented to directly synthesize amorphous FexNiy hydroxide nanoclusters (denoted as ANC-FexNiy, <2 nm) with oxygen vacancies induced by ionic liquids. The ANC-FexNiy catalyst presents abundant catalytic sites and high intrinsic conductivity. As such, the optimized ANC-Fe1Ni2 exhibits high activity in oxygen evolution reaction (OER) with a Tafel slope of 39 mV dec-1 and an overpotential of 266 mV at 10 mA cm-2. Notably, the optimized ANC-Fe1Ni2 shows an extraordinarily large mass activity of 3028 A gFeNi-1 at the overpotential of 300 mV, which is ∼24-fold of commercial RuO2 catalyst. The superior activity of these FexNiy hydroxide nanoclusters is ascribed to (i) the amorphous and distorted structure with abundant oxygen vacancies, and (ii) enhanced active site density by downsizing the ANC-FexNiy clusters. This strategy provides a novel route for enhancing OER electrocatalytic performance and highly encouraging for the future application of amorphous metal hydroxides in catalysis.

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3D flame-retardant skeleton reinforced polymer electrolyte for solid-state dendrite-free lithium metal batteries Xiaojiao Zheng, Jiawei Wu, Jing Chen, Xiaodong Wang, Zhenglong Yang 2022, 71(8): 174-181.  DOI: 10.1016/j.jechem.2022.03.010 Abstract ( 2 )   PDF (5904KB) ( 2 )   For solid polymer electrolytes (SPEs), improving their mechanical and electrochemical properties is the key to obtaining batteries with higher safety and higher energy density. Herein, a novel synergistic strategy proposed is preparing a 3D flame-retardant skeleton (3DPA) and adding nano-multifunctional fillers (Li-ILs@ZIF-8). In addition to providing mechanical support for the polyethylene oxide (PEO) matrix, 3DPA also has further contributed to the system's flame retardancy and further improved the safety. Simultaneously, the electrochemical performance is fully guaranteed by rigid Li-ILs@ZIF-8, which provides fast migration channels for Li+, reduces the crystallinity of PEO and effectively inhibits lithium dendrites. The limiting oxygen index of the optimal sample (PL3Z/PA) is as high as 20.5%, and the ionic conductivity reaches 2.89 × 10-4 and 0.91 × 10-3 S cm-1 at 25 and 55 °C, respectively. The assembled Li|PL3Z/PA|Li battery can be cycled stably for more than 1000 h at a current density of 0.1 mA cm-2 without short circuit being pierced by lithium dendrites. The specific capacity of the LFP|PL3Z/PA|Li battery was 160.5 mAh g-1 under a current density of 0.5 C, and the capacity retention rate was 90.0% after 300 cycles.

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Breaking the linear correlations for enhanced electrochemical nitrogen reduction by carbon-encapsulated mixed-valence Fe7(PO4)6 Lehui Ma, Fanfan Xu, Linlin Zhang, Zhongfen Nie,Kai Xia, Mingxia Guo, Mingzhu Li, Xin Ding 2022, 71(8): 182-187.  DOI: 10.1016/j.jechem.2022.03.042 Abstract ( 3 )   PDF (4603KB) ( 2 )   Electrochemical nitrogen reduction (NRR) is deemed as a consummate answer for the traditional Haber-Bosch technology. Breaking the linear correlations between adsorption and transition-state energies of intermediates is vital to improve the kinetics of ammonia synthesis and obtain a less energy-intensive process. Herein, carbon-encapsulated mixed-valence Fe7(PO4)6 was prepared and applied as an electrocatalyst for high-efficiency NRR. A dramatic faradaic efficiency (FE) of 36.93% and an NH3 production rate of 13.1 μg h-1 mgcat.-1 were obtained at -0.3 V versus RHE, superior to nearly all Fe-based catalysts. Experiments and DFT calculations revealed that the superior performance was ascribed to the synergistic effect of mixed-valence iron pair, which braked the linear correlations to improve the kinetics of ammonia from collaborative hydrogenation and *NH3 separation. This work proves the feasibility of mixed-valence catalysts for nitrogen reduction and thus opening a new avenue towards artificial nitrogen-fixation catalysts.

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A new pathway for formic acid electro-oxidation: The electro-chemically decomposed hydrogen as a reaction intermediate Xiaolong Yang, Qinglei Meng, Xian Wang, Zhao Jin, Changpeng Liu, Junjie Ge, Wei Xing 2022, 71(8): 188-191.  DOI: 10.1016/j.jechem.2022.03.036 Abstract ( 7 )   PDF (3922KB) ( 2 )   Formic acid electro-oxidation reaction (FAOR) is generally believed that follows a two-pathway mechanism. Herein, we resorted to in situ electrochemical mass spectrometry and successfully captured the trace of H2, as the new intermediate species, during the process of FAOR on both Pt based catalyst and two single atom catalysts (Rh-N-C and Ir-N-C). Inspired by this, we proposed a new reaction path named hydrogen oxidation pathway: at the oxidation potential, formic acid will break the C-H bond and combine with the protons in the solution to form H2 species, then hydrogen oxidation reaction (HOR) will occur to generate two protons. This process is accompanied by electron transfer and contributes currently to the whole reaction.

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Wet spinning of fiber-shaped flexible Zn-ion batteries toward wearable energy storage Tingting Gao, Guangyuan Yan, Xin Yang, Qing Yan, Yankuan Tian, Jianwei Song, Faxue Li, Xueli Wang, Jianyong Yu, Yiju Li, Shaojun Guo 2022, 71(8): 192-200.  DOI: 10.1016/j.jechem.2022.02.040 Abstract ( 21 )   PDF (7088KB) ( 8 )   High-performance flexible one-dimensional (1D) electrochemical energy storage devices are crucial for the applications of wearable electronics. Although much progress on various 1D energy storage devices has been made, challenges involving fabrication cost, scalability, and efficiency remain. Herein, a high-performance flexible all-fiber zinc-ion battery (ZIB) is fabricated using a low-cost, scalable, and efficient continuous wet-spinning method. Viscous composite inks containing cellulose nanofibers/carbon nanotubes (CNFs/CNTs) binary composite network and either manganese dioxide nanowires (MnO2 NWs) or commercial Zn powders are utilized to spinning fiber cathodes and anodes, respectively. MnO2 NWs and Zn powders are uniformly dispersed in the interpenetrated CNFs/CNTs fibrous network, leading to homogenous composite inks with an ideal shear-thinning property. The obtained fiber electrodes demonstrate favorable uniformity and flexibility. Benefiting from the well-designed electrodes, the assembled flexible fiber-shaped ZIB delivers a high specific capacity of 281.5 mAh g-1 at 0.25 A g-1 and displays excellent cycling stability over 400 cycles. Moreover, the wet-spun fiber-shaped ZIBs achieve ultrahigh gravimetric and volumetric energy densities of 47.3 Wh kg-1 and 131.3 mWh cm-3, respectively, based on both cathode and anode and maintain favorable stability even after 4000 bending cycles. This work offers a new concept design of 1D flexible ZIBs that can be potentially incorporated into commercial textiles for wearable and portable electronics.

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Point-defect engineering of nanoporous CuBi2O4 photocathode via rapid thermal processing for enhanced photoelectrochemical activity Li Qu, Runfa Tan, Arumugam Sivanantham, Min JeKang, Yoo Jae Jeong, Dong Hyun Seo, Sungkyu Kim, In Sun Cho 2022, 71(8): 201-209.  DOI: 10.1016/j.jechem.2022.03.013 Abstract ( 40 )   PDF (5581KB) ( 10 )   Engineering point defects such as metal and oxygen vacancies play a crucial role in manipulating the electrical, optical, and catalytic properties of oxide semiconductors for solar water splitting. Herein, we synthesized nanoporous CuBi2O4 (np-CBO) photocathodes and engineered their surface point defects via rapid thermal processing (RTP) in controlled atmospheres (O2, N2, and vacuum). We found that the O2-RTP treatment of np-CBO increased the charge carrier density effectively without hampering the nanoporous morphology, which was attributed to the formation of copper vacancies (VCu). Further analyses revealed that the amounts of oxygen vacancies (Vo) and Cu1+ were reduced simultaneously, and the relative electrochemical active surface area increased after the O2-RTP treatment. Notably, the point defects (VCu, Cu1+, and Vo) regulated np-CBO achieved a superb water-splitting photocurrent density of -1.81 mA cm-2 under simulated sunlight illumination, which is attributed to the enhanced charge transport and transfer properties resulting from the regulated surface point defects. Finally, the reversibility of the formation of the point defects was checked by sequential RTP treatments (O2-N2-O2-N2), demonstrating the strong dependence of photocurrent response on the RTP cycles. Conclusively, the surface point defect engineering via RTP treatment in a controlled atmosphere is a rapid and facile strategy to promote charge transport and transfer properties of photoelectrodes for efficient solar water-splitting.

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Construction of polysulfides defense system for greatly improving the long cycle life of metal sulfide anodes for sodium-ion batteries Xucai Yin, Yang Ren, Libin Wu, Zhiguo Zhang,Chunyu Du, Jiajun Wang,Gepin Yin, Hua Huo 2022, 71(8): 210-217.  DOI: 10.1016/j.jechem.2022.03.012 Abstract ( 10 )   PDF (3328KB) ( 5 )   Metal sulfides are promising anode materials for sodium ion batteries (SIBs) due to their high theoretical specific capacity and abundant source. Nevertheless, significant challenges, including large volume change, sluggish Na+ transport kinetics and polysulfides intermediates, have greatly affect their long cycle stability. Unfortunately, the majority of current studies only focus on the first two aspects, but lack of sufficient attention and insights into the effect of polysulfides intermediates. Here, a porous of CoSx (P-CoSx) electrode material is fabricated as an example to investigate the influence of polysulfides on its cycling performance. The results show that polysulfides cause a slight loss of reversible capacity during the battery cycling, while the failure of the battery is due to its significant fluctuations in reversible capacity after extensive cycles. Detailed analyses demonstrate that the intense fluctuation in capacity originates from the faster growth of dendrites caused by the reaction of sodium polysulfides with sodium foil and/or the reaction of elemental sulfur with sodium foil to penetrate the separator, resulting in a local short circuit. To suppress these undesirable side reaction, N, S co-doped porous carbon tubes (N, S-PC) rich in C-S and C-N bonds have been added to adsorb polysulfides and alleviate their reaction with sodium foil. As a result, the capacity of the P-CoSx electrode with N, S-PC (P-CoSx/N, S-PC) remains stable without significant fluctuations for 1000 cycles, which is much better than that of the pure P-CoSx electrode (intense fluctuation in capacity after 320 cycles). Our work offers insights into the crucial influence of polysulfides on the cycle performance of the P-CoSx anode and provides a feasible strategy to prolong the cycle life of metal sulfide anode for SIBs.

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Bifunctional LiI additive for poly(ethylene oxide) electrolyte with high ionic conductivity and stable interfacial chemistry Haonan Wang,Tianyi Hou, Hang Cheng,Bowen Jiang,Henghui Xu, Yunhui Huang 2022, 71(8): 218-224.  DOI: 10.1016/j.jechem.2022.02.041 Abstract ( 9 )   PDF (3952KB) ( 4 )   The development of polymer-based solid-state batteries is severely limited by the low ionic conductivity of solid polymer electrolyte and the instable interface between polymer electrolyte and Li-metal anode. In this work, lithium iodide (LiI) as a bifunctional additive was introduced into the poly(ethylene oxide) (PEO)-based electrolyte to improve the ionic conductivity and to construct a stable interphase at the Li/PEO interface. I- anions offer a strong electrostatic interaction with hydrogen atoms on PEO chains (HPEO) and forming massive I-H bonds that cross-link PEO chains, decrease crystallinity of PEO, and thus improve Li+ interchain transport. In addition, LiI participates in the formation of an inorganic-rich interphase layer, which decreases the energy barrier of Li+ transport across the interface and thus inhibits the growth of lithium dendrites. As a result, the composite PEO electrolyte with 2 wt% LiI (PEO-2LiI) presents a very high ionic conductivity of 2.1 × 10-4 S cm-1 and a critical current density of 2.0 mA cm-2 at 45 °C. Li symmetric cell with this PEO-2LiI electrolyte exhibits a long-term cyclability over 600 h at 0.2 mA cm-2. Furthermore, solid-state LiFePO4 and LiNi0.8Mn0.1Co0.1O2 batteries with the PEO-2LiI electrolyte show an impressive electrochemical performance with outstanding cycling stability and rate capability at 45 °C.

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Understanding the promotional effects of trace doped Zn in Co/NC for efficient one-pot catalytic conversion of furfural to 2-methyl-tetrahydrofuran Lei Huang, Liqiang Wang, Zonghao Zhang, Xinpeng Guo, Xiaowen Zhang, Johnny Muya Chabu, Pingle Liu, Feiying Tang 2022, 71(8): 225-233.  DOI: 10.1016/j.jechem.2022.03.031 Abstract ( 6 )   PDF (5239KB) ( 4 )   2-methyl-tetrahydrofuran (2-MTHF) is a promising biofuel or fuel additive with excellent burning property, a versatile new-style solvent in organic synthesis, and an important medical intermediate. In this work, a one-pot selective conversion of furfural (FA) into 2-MTHF was carried out over Zn doped Co/NC catalysts. The Zn-Co/NC-1 catalyst with trace Zn dopant (0.38 wt%) exhibited the best performance (yield of 2-MTHF: 93.8%). According to the characterizations, it was found that the Zn not only incorporates into the carbon support but also partially dopes into Co nanoparticles. Subsequently, theoretical calculations demonstrated that the doping of Zn in carbon support can effectively enhance the electron transfer from the support to the metallic Co particle, leading to the electron-rich Co surface. The presence of Zn was found to promote the dissociation of hydrogen and to lower the diffusion barrier of hydrogen atom, in favor of the hydrogenation/hydrodeoxygenation processes. Furthermore, the Zn doped models exhibit much lower barrier in breaking C-OH bond of FOL, resulting in higher activity for hydrodeoxygenation of FOL. These theoretical results are consistent with the in situ FT-IR analysis of adsorption substrates and intermediates over Zn doped catalyst. This work reveals the mechanism of dopant Zn tailoring the electronic structure and catalytic performance of active sites, providing a deep insight into the design of economical and high-performance catalysts for hydrogenation/hydrodeoxygenation of biomass feedstocks.

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Carbon-based bifunctional electrocatalysts for oxygen reduction and oxygen evolution reactions: Optimization strategies and mechanistic analysis Huidong Xu, Jack Yang, Riyue Ge, Jiujun Zhang, Ying Li, Mingyuan Zhu, Liming Dai, Sean Li, Wenxian Li 2022, 71(8): 234-265.  DOI: 10.1016/j.jechem.2022.03.022 Abstract ( 49 )   PDF (24497KB) ( 43 )   Electrocatalysts are one of the essential components for the devices of high-efficiency green energy storage and conversion, such as metal-air cells, fuel cells, and water electrolysis systems. While catalysts made from noble metals possess high catalytic performance in both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), their scarcity and expensiveness significantly limit large-scale applications. In this regard, metal-free/non-noble metal carbon-based catalysts have become competitive alternatives to replace catalysts made of noble metals. Nevertheless, low catalytic ORR/OER performance is the challenge of carbon-based catalysts for the commercial applications of metal-air batteries. To solve the problem of poor catalytic performance, two strategies have been proposed: (1) controlling the microstructure of the catalysts to expose more active sites as the channels of rapid mass and electron transfer; and (2) reducing the reaction energy barrier by optimizing the electronic structures of the catalysts via surface engineering. Here, we review different types of bifunctional ORR/OER electrocatalysts with the activated surface sites. We focus on how the challenge can be overcome with different methods of material synthesis, structural and surface characterization, performance validation/optimization, to outline the principles of surface modifications behind catalyst designs. In particular, we provide critical analysis in the challenges that we are facing in structural design and surface engineering of bifunctional ORR/OER catalysts and indicate the possible solution for these problems, providing the society with clearer ideas on the practical prospects of noble-metal-free electrocatalysts for their future applications.

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Tuning redox activity through delithiation induced protective layer and Fe-O coordination for Li-rich cathode with improved voltage and cycle performance Kanghui Hu, Li Ren, Weifeng Fan, Bing Zhang, Meihua Zuo, Yanhui Zhang, Genpin Lv, Huiyuan Xu, Wei Xiang, Xiaodong Guo 2022, 71(8): 266-276.  DOI: 10.1016/j.jechem.2022.03.046 Abstract ( 6 )   PDF (9368KB) ( 1 )   Li-rich layered transition metal oxides are one of the most promising cathode materials for their high energy density. However, the cathodes usually suffer from severe potential dropping and capacity fading during cycling, which are associated with the surface oxygen release and accompanied by cation densification and structural collapse. Herein, an integrative approach of simultaneous constructing uniform 3d Fe-ion doping in the transition metal layer and Li-rich Li5FeO4 shell to grab the oxygen and prevent interfacial side reactions is proposed. The introduction of Fe induces higher redox potential and stronger 3d Fe-O 2p covalent bond, triggering reversible anionic redox via a reductive coupling mechanism. And the delithiated product of Li-rich Li5FeO4 not only acts as a protective layer alleviating the side reactions but also enhances the surface kinetic property. With the benefit of promoted reversibility of oxygen redox and enhanced surface stability, the cathode exhibits high reversible capacity and superior cycle performance. Density function theory calculation indicates that the O 2p non-bonding state in the cathode incorporated with Fe sits at a lower energy band, resulting in higher energy storage voltage and improved oxygen stability. Consequently, the modified cathode exhibits a discharge specific capacity of 307 mA h g-1 (1C = 250 mA g-1), coulombic efficiency of 82.09% in the initial cycle at 0.1C and 88.34% capacity retention after 100 cycles at 1C. The work illustrates a strategy that could simultaneously enhance oxygen redox reversibility and interface stability by constructing lattice bond coordination and delithiation induced protective layer to develop Li-rich materials with high reversible capacity and long lifespan.

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Hollow structured Cu@ZrO2 derived from Zr-MOF for selective hydrogenation of CO2 to methanol Xiaoyu Han, Maoshuai Li, Xiao Chang, Ziwen Hao, Jiyi Chen, Yutong Pan, Sibudjing Kawi, Xinbin Ma 2022, 71(8): 277-287.  DOI: 10.1016/j.jechem.2022.03.034 Abstract ( 6 )   PDF (6295KB) ( 4 )   The development of a highly efficient catalyst for CO2 activation and selective conversion to methanol is critical to address the issues associated with the high thermal stability of CO2 and controllable synthesis of methanol. Cu-based catalysts have been widely studied because of the low cost and excellent performance in mild conditions. However, the improvement of catalytic activity and selectivity remains challenging. Herein, we prepared hollow Cu@ZrO2 catalysts through pyrolysis of Cu-loaded Zr-MOF for CO2 hydrogenation to methanol. Low-temperature pyrolysis generated highly dispersed Cu nanoparticles with balanced Cu0/Cu+ sites, larger amounts of surface basic sites and abundant Cu-ZrO2 interface in the hollow structure, contributing to enhanced catalytic capacity for adsorption/activation of CO2 and selective hydrogenation to methanol. In situ Fourier Transform Infrared Spectroscopy revealed the methanol formation followed the formate-intermediated pathway. This work would provide a guideline for the design of high-performance catalysts and the understanding of the mechanism and active sites for CO2 hydrogenation to methanol.

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Zeolites for separation: Fundamental and application Bin Yue, Shanshan Liu, Yuchao Chai, Guangjun Wu, Naijia Guan, Landong Li 2022, 71(8): 288-303.  DOI: 10.1016/j.jechem.2022.03.035 Abstract ( 9 )   PDF (5871KB) ( 9 )   Material based emerging separation techniques are attracting more and more attention as alternatives to the traditional ones such as distillation and extraction, aiming to reduce energy consumption and pollutant emissions. Due to their structure characteristics, zeolites can act as versatile sieves and adsorbents for molecules and have been successfully applied in some very important separation processes. Herein, two major catalogues of zeolite separations, namely membrane separation and adsorptive separation, are discussed and their underlying mechanisms are focused . In the part of membrane separation, the synthesis strategies toward zeolite membranes are introduced and the uniformly-oriented zeolite membranes are emphasized. In the part of the adsorptive separation, the industrial and popular adsorptive separations with the corresponding zeolite adsorbents are summarized. Generally, membrane separation relies on the molecular diffusion behavior within zeolites while adsorptive separation relies on the guest-host interaction in principle. The key challenges and misconceptions in zeolite separations are highlighted throughout the article.

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Nest-type NCM ⊂ Pt/C with oxygen capture character as advanced electrocatalyst for oxygen reduction reaction Teng Chen, Yida Xu, Deming Meng, Xuefeng Guo, Yan Zhu, Luming Peng, Jianqiang Hu, Weiping Ding 2022, 71(8): 304-312.  DOI: 10.1016/j.jechem.2022.03.017 Abstract ( 3 )   PDF (6947KB) ( 2 )   A unique nest-type catalyst has been designed with a nest of oxygen capture surrounding catalytic Pt centers, which shows much promoted performance, on the base of Pt/C catalyst, for oxygen reduction reaction (ORR). The nest is constructed with nitrogen-doped carbon matrix (NCM), derived from the controlled carbonization of PANI precursor, to cover Pt/C catalyst. The unique structure of the catalyst (denoted as NCM ⊂ Pt/C) has many merits. Firstly, it can capture oxygen both in air and in acidic electrolyte. Compared with naked Pt/C, it is found that, in air, the oxygen concentration within the porous nest of NCM surrounding Pt/C particles is ∼13 times higher than atmospheric oxygen concentration and, in acidic electrolyte, the concentration of activated oxygen over the catalyst NCM ⊂ Pt/C rise to ∼1.9 times. Secondly, the NCM nest offers a special electronic modulation on Pt centers toward modified ORR kinetics and then catalytic performances. With these merits, compared with Pt/C, the NCM ⊂ Pt/C catalyst shows 3.2 times higher turnover frequency value and 2.9 times enhanced specific activity for ORR with half-wave potential at 0.894 V. After 50,000 sweeping cycles, the NCM ⊂ Pt/C catalyst retains ∼66% mass activity and still has advantages over the fresh Pt/C catalyst. We envision that the nest-type catalyst provides a new idea for progress of practical Pt/C ORR catalyst.

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Advances on Na-K liquid alloy-based batteries Junwei Wu, Zhuang Xue,Lixuan Yuan, Jilei Ye,Qinghong Huang, Lijun Fu, Yuping Wu 2022, 71(8): 313-323.  DOI: 10.1016/j.jechem.2022.03.027 Abstract ( 13 )   PDF (5717KB) ( 7 )   Sodium-potassium (Na-K) liquid alloys attract increasing research attention, as an ideal alternative of Li metal for metal-based batteries, attributing to their high abundance, low redox potential, high capacity, and dendrite-free properties. In addition, the liquid and self-healing features of Na-K alloys endow good electrode/electrolyte interfacial contact. The recent advances on the Na-K liquid alloy-based batteries (NKBs) are reviewed herein. The anode designs for immobilization of the liquid alloy are introduced. The influences of the electrolyte and cathode materials on the battery performances are discussed. In addition, considering the co-existence of both K+ and Na+ in the electrolyte, the working mechanisms of the NKBs are elaborated. We also show that despite the improvement, challenges of the NKBs remain. The compatibility between Na-K liquid alloy and electrolyte, as well as disputed working mechanisms, request detailed surface analyses of the liquid alloy and local element distribution evolution in the battery. This review would shed light on the fundamental understanding of Na-K alloy electrochemistry and the development of dendrite-free metal-based energy storage systems with high energy density.

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Unveiling the role of lithiophilic sites denseness in regulating lithium ion deposition Tianlai Wu, Yongyin Wang, Weicai Zhang, Kaixin Lu, Jieyin Tan, Mingtao Zheng, Yong Xiao, Yingliang Liu, Yeru Liang 2022, 71(8): 324-332.  DOI: 10.1016/j.jechem.2022.03.039 Abstract ( 4 )   PDF (7306KB) ( 2 )   The construction of lithiophilic sites is an effective way to achieve uniform lithium (Li) ion deposition for stably cycling Li metal batteries. However, in-depth investigations involving lithiophilic sites denseness (LSD) in impacting Li ion deposition remain unknown. Herein we propose an insight into this issue by probing the effect of LSD on determining the Li ion deposition. Experimental characterization and theoretical simulation demonstrate that rational LSD plays a vital role in both Li nucleation and the subsequent Li ion plating behaviors. By tailoring the LSD from low to high, the accompanied Li nucleation overpotentials continuously decrease. Additionally, the Li ion mobility increases first and then weakens in the subsequent Li ion plating stage. Consequently, the Li metal with a moderate LSD allows a dendrite-free morphology and satisfactory long-term cycling performances. This work affords a deeper fundamental understanding of lithiophilic chemistry that directs the development of efficient strategies to realize dendrite-free Li metal batteries.

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Advanced heterolytic H2 adsorption of K-added Ru/MgO catalysts for accelerating hydrogen storage into aromatic benzyltoluenes Tae Wan Kim, Hwiram Jeong, Yeongin Jo, Dongun Kim, Ji Hoon Park, Seok Ki Kim, Young-Woong Suh 2022, 71(8): 333-343.  DOI: 10.1016/j.jechem.2022.03.047 Abstract ( 4 )   PDF (4327KB) ( 2 )   Herein, we report a highly active K-added Ru/MgO catalyst for hydrogen storage into aromatic benzyltoluenes at low temperatures to advance liquid organic hydrogen carrier technology. The hydrogenation activity of Ru/K/MgO catalysts exhibits a volcano-shaped dependence on the K content at the maximum with 0.02 wt%. This is in good agreement with the strength and capacity of H2 adsorption derived from basicity, despite a gradual decrease in the textural property and the corresponding increase in the Ru particle size with increasing the K content. Density functional theory calculations show that heterolytic hydrogen adsorption properties (strength and polarization) are facilitated up to a specific density of K on the Ru-MgO interface and excessive K suppresses heterolytic H2 adsorption by direct interaction between K and hydrogen, assuring the hydrogenation activity and H2 adsorption capability of Ru/K/MgO catalysts. Hence, the Ru/K/MgO catalyst, when K is added in an optimal amount, is highly effective to accelerate hydrogen storage kinetics at low temperatures owing to the enhanced heterolytic H2 adsorption.

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Stabilizing SEI by cyclic ethers toward enhanced K+ storage in graphite Jiesong Zhang, Jian-Fang Wu, Zixing Wang, Ying Mo, Wang Zhou, Yufan Peng, Bingchen He, Kuikui Xiao, Shi Chen, Chaohe Xu, Jilei Liu 2022, 71(8): 344-350.  DOI: 10.1016/j.jechem.2022.03.021 Abstract ( 7 )   PDF (12770KB) ( 4 )   The poor cycling stability of graphite in traditional ester electrolyte limits its applications as anodes for potassium ion batteries (KIBs). Herein, we demonstrate that the introduction of cyclic ether co-solvents into ester electrolytes can remarkably enhance the cycling stability of graphite anodes. The graphite anode in ester electrolyte with cyclic ether could achieve a reversible capacity of 196.1 mAh g-1 after 100 cycles at 0.3 C (1 C = 280 mA g-1), about three times higher than those in ester electrolytes with or without linear ether. Compared with the SEI formed in ester electrolytes, the addition of tetrahydrofuran promotes the generation of K2CO3 and ethylene oxide oligomers (PEO), of which the K2CO3 is expected to be more conductive and PEO is mechanically robust. The more uniform, conductive and stable solid electrolyte interphases (SEIs) on graphite in electrolytes with cyclic ethers contribute to the enhancement of the electrochemical performances of graphite. This work provides a novel design of commercialized electrolytes to achieve high-performance anodes for KIBs, which potentially accelerates the development of KIBs.

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Should we recycle the graphite from spent lithium-ion batteries? The untold story of graphite with the importance of recycling Subramanian Natarajan, Madhusoodhanan Lathika Divya, Vanchiappan Aravindan 2022, 71(8): 351-369.  DOI: 10.1016/j.jechem.2022.04.012 Abstract ( 37 )   PDF (12208KB) ( 22 )   Demand for graphite in the forthcoming years to develop Li-ion batteries (LIBs) with the goal of driving electric vehicles (EV) and its requirement in multifarious energy storage applications as an electrode. The emerging sector of LIB-based EVs, along with portable electronics, produces an inevitable volume of batteries in the e-waste stream. The main reason for the lower percentage of recycling (at present, <5%) is due to the recovery of economically rich metals like Li, Ni, and Co. However, complete recycling technologies, including the strategic material graphite, which is available in a massive amount of spent LIBs, are urgently needed to be updated to ensure the reuse of all components. This approach lifts the recycling process to develop an economic one besides the geostrategic and environmental policy aspects. Here, we summarize the importance of graphite and its demand and specify the reasons to recycle the graphite from spent LIBs along with its development as an anode in detail. Additionally, the approach of the current recycling process of graphite in lab-scale and industries for various applications, including energy storage, are discussed with the highlights of future progress.

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Understanding the growth mechanisms of metal-based core-shell nanostructures revealed by in situ liquid cell transmission electron microscopy Junyu Zhang, Bensheng Xiao, Junhui Zhao, Miao Li, Haichen Lin, Zewen Kang, Xianwen Wu, Haodong Liu, Dong-Liang Peng, Qiaobao Zhang 2022, 71(8): 370-383.  DOI: 10.1016/j.jechem.2022.04.007 Abstract ( 7 )   PDF (15546KB) ( 2 )   Metal-based core-shell nanostructures have garnered enduring interest due to their unique properties and functionalities. However, their growth and transformation mechanisms in liquid media remain largely unknown because they lack direct observation of the dynamic growth process with high spatial and temporal resolution. Developing the in situ liquid cell transmission electron microscopy (TEM) technique offers unprecedented real-time imaging and spectroscopy capabilities to directly track the evolution of structural and chemical transformation of metal-based core-shell nanostructures in liquid media under their working condition. Here, this review highlights recent progress in utilizing in situ liquid cell TEM characterization technique in investigating the dynamic evolution of material structure and morphology of metal-based core-shell nanostructures at the nano/atomic scale in real-time. A brief introduction of the development of liquid cells for in situ TEM is first given. Subsequently, recent advances in in situ liquid cell TEM for the fundamental study of growth mechanisms of metal based core-shell nanostructures are discussed. Finally, the challenge and future developments of metal-based core-shell nanostructures for in situ liquid cell TEM are proposed. Our review is anticipated to inspire ongoing interest in revealing unseen growth dynamics of core-shell nanostructures by in situ liquid cell TEM technique.

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In-situ formation of Li0.5Mn0.5O coating layer through defect controlling for high performance Li-rich manganese-based cathode material Aipeng Zhu, Qin Wang, Yin Zhang, Yueyin Zhang, Xiaogang He, Kaipeng Wu, Hao Wu, Qian Wang, Wenlong Cai, Yun Zhang 2022, 71(8): 384-391.  DOI: 10.1016/j.jechem.2022.04.005 Abstract ( 7 )   PDF (8423KB) ( 3 )   Li-rich layered oxide of Li1.2Mn0.6Ni0.2O2 (LMNO) with a considerable specific capacity and higher voltage is regarded as a kind of promising cathode material. However, it suffers from transition metal ion dissolution and oxygen escape that leads to rapid capacity decay. In addition, the poor lithium-ion diffusion kinetics gives rise to unsatisfied rate performance. Herein, a stable layer of Li0.5Mn0.5O (LMO) out of LMNO is in-situ constructed through acetic passivation and following calcination process. The generated defect structure in the composite material exhibits fast ion diffusion kinetics and the produced LMO layer can stabilize the substructure, resulting in elevated cycling stability and rate performance. In specific, the LMNO@LMO material exhibits a high initial coulombic efficiency of 80.3% and remarkable capacity retention of 80.7% after 200 cycles at 1 C. Besides, the composite material reveals prominent rate performance that delivers discharge capacities of 158 and 131 mAh g-1 at 5 and 10 C, respectively. At last, this study presents a new approach to optimizing the Li-rich cathode materials.

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Boosting the kinetics of PF6- into graphitic layers for the optimal cathode of dual-ion batteries: The rehearsal of pre-intercalating Li+ He Yang, Tingting Qin, Xinyan Zhou, Yu Feng, Zizhun Wang, Xin Ge, Nailin Yue, Dabing Li, Wei Zhang, Weitao Zheng 2022, 71(8): 392-399.  DOI: 10.1016/j.jechem.2022.04.009 Abstract ( 4 )   PDF (2814KB) ( 2 )   Large anions exhibit slow diffusion kinetics in graphite cathode of dual-ion batteries (DIBs); particularly at high current density, it suffers severely from the largely-reduced interlayer utilization of graphite cathode, which as a bottleneck limits the fast charge application of DIBs. To maximize interlayer utilization and achieve faster anion diffusion kinetics, a fast and uncrowded anion transport channel must be established. Herein, Li+ was pre-intercalated into the graphite paper (GP) cathode to increase the interlayer spacing, and then hosted for the PF6-anion storage. Combined with theoretical calculation, it shows that the local interlayer spacing enlargement and the residual Li+ reduce the anion intercalation energy and diffusion barrier, leading to better rate stability. The obtained GP with Li+ pre-intercalation (GP-Li) electrode exhibits a discharge capacity of 23.1 mAh g-1 at a high current of 1300 mA g-1. This work provides a facile method to efficiently improve the interlayer utilization of graphite cathode at large currents.

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Rational construction and decoration of Li5Cr7Ti6O25@C nanofibers as stable lithium storage materials Ting-Ting Wei, Panpan Peng, Yu-Rui Ji, Yan-Rong Zhu, Ting-Feng Yi, Ying Xie 2022, 71(8): 400-410.  DOI: 10.1016/j.jechem.2022.04.017 Abstract ( 7 )   PDF (11157KB) ( 1 )   Li5Cr7Ti6O25 is regarded as a promising anode material for Li-ion batteries (LIBs) because of its low cost and high theoretical capacity. However, the inherently poor conductivity significantly limits the enhancement of its rate capability and cycling stability, especially at high current densities. In this work, we construct one-dimensional Li5Cr7Ti6O25/C nanofibers by electrospinning method to enhance the kinetic, which realizes high cycling stability. Carbon coating enhances the structure stability, insertion/extraction reversibility of Li-ions and electrochemical reaction activity, and facilitates the transfer of Li-ions. Benefited from the unique architecture and component, the Li5Cr7Ti6O25/C (6.6 wt%) nanofiber shows an excellent rate capability with a reversible de-lithiation capacity of 370.8, 290.6, 269.2, 254.3 and 244.9 mAh g-1 at 200, 300, 500, 800 and 1000 mA g-1, respectively. Even at a higher current density of 1 A g-1, Li5Cr7Ti6O25 /C (6.6 wt%) nanofiber shows high cycling stability with an initial de-lithiation capacity of 237.8 mAh g-1 and a capacity retention rate of about 84% after 500 cycles. The density functional theory calculation result confirms that the introduction of carbon on the surface of Li5Cr7Ti6O25 changes the total density of states of Li5Cr7Ti6O25, and thus improves electronic conductivity of the composite, resulting in a good electrochemical performance of Li5Cr7Ti6O25/C nanofibers. Li5Cr7Ti6O25/C nanofibers indicate a great potential as an anode material for the next generation of high-performance LIBs.

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Sulfonic groups functionalized Zr-metal organic framework for highly catalytic transfer hydrogenation of furfural to furfuryl alcohol Jingcheng Wu, Dong Liang, Xiangbo Song, Tingsen Liu, Tianyi Xu, Shuangyin Wang, Yuqin Zou 2022, 71(8): 411-417.  DOI: 10.1016/j.jechem.2022.02.047 Abstract ( 8 )   PDF (2966KB) ( 4 )   The highly selective catalytic transfer hydrogenation (CTH) of furfural (FF) to furfuryl alcohol (FOL) is a significant route of biomass valorization. Herein, a series microporous Zr-metal organic framework (Zr-MOF) functionalized by sulfonic groups are prepared. Based on the comprehensive structural characterizations by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 physisorption, Thermogravimetric (TG) and Fourier transformed infrared spectroscopy (FTIR), we find that sulfonic acid (-SO3H) functional groups are tethered on the UIO-66 without affecting the structure of the framework. Systematic characterizations (NH3-TPD, CO2-TPD, and in-situ FTIR) demonstrate that modifying of sulfonic groups on UIO-66 results in the formation of stronger Lewis acidic-basic and Brønsted acidis sites. The cooperative role of the versatile Lewis acidic-basic and Brønsted acidic sites in 60% mol fraction of sulfonic acid-containing UIO-66 (UIO-S0.6) retain high surface area and exhibit excellent catalytic performance of 94.7% FOL yield and 16.9 h-1 turnover number (TOF) under mild conditions. Kinetic experiments reveal that the activation energy of the CTH of furfural (FF) over UIO-S0.6 catalyst is as low as 50.8 kJ mol-1. Besides, the hydrogen transfer mechanism is investigated through isotope labeling experiments, exhibiting that the β-H in isopropanol is transferred to the α-C of FF by forming six-membered intermediates on the Lewis acidic-basic and Brønsted acidic sites of the UIO-S0.6, which is the rate-determining step in the formation of FOL.

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Developments and challenges ahead in blue perovskite light-emitting devices Lin Zhang,Run Long 2022, 71(8): 418-433.  DOI: 10.1016/j.jechem.2022.04.001 Abstract ( 11 )   PDF (5344KB) ( 4 )   Recently, perovskite light-emitting diodes (PeLEDs) have developed rapidly in the green, red, and near-infrared light emissions, owing to the unique optoelectronic characteristics of halide perovskites, such as high carrier mobility, narrow emission linewidths, high photoluminescence quantum yield, as well as bandgap tunability. However, the efficiency improvement in blue (especially deep-blue) PeLEDs is still inferior to other analogs, which severely restricts the PeLED applications. Here, we systematically summarize the substantial progress in the performance of blue PeLEDs based on different blue perovskite candidates, and recent advances from three aspects (i.e., the sky-blue, pure-blue, and deep-blue light emissions). Then, we point out several challenges existing in deep-blue PeLEDs, such as the effect of Cl- ions incorporation, spectral instability, ion migration, and the difficulty of charge injection, and highlight the strategies to improve device efficiency, to motivate further research and development of blue PeLEDs.

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Mg,Ti-base surface integrated layer and bulk doping to suppress lattice oxygen evolution of Ni-rich cathode material at a high cut-off voltage Fan Peng, Youqi Chu, Yu Li, Qichang Pan, Guangchang Yang, Lixuan Zhang, Sijiang Hu, Fenghua Zheng, Hongqiang Wang, Qingyu Li 2022, 71(8): 434-444.  DOI: 10.1016/j.jechem.2022.03.053 Abstract ( 7 )   PDF (15422KB) ( 4 )   The Nickel-rich layered cathode materials charged to 4.5 V can obtain a specific capacity of more than 200 mAh g-1. However, the nickel-rich layered cathode materials suffer from the severe capacity fade during high-voltage cycling, which is related to the phase transformation and the surface sides reactions caused by the lattice oxygen evolution. Here, the simultaneous construction of a Mg, Ti-based surface integrated layer and bulk doping through Mg, Ti surface treatment could suppress the lattice oxygen evolution of Ni-rich material at deep charging. More importantly, Mg and Ti are co-doped into the particles surface to form an Mg2TiO4 and Mg0.5-xTi2-y(PO4)3 outer layer with Mg and Ti vacancies. In the constructed surface integrated layer, the reverse electric field in the Mg2TiO4 effectively suppressed the outward migration of the lattice oxygen anions, while Mg0.5-xTi2-y(PO4)3 outer layer with high electronic conductivity and good lithium ion conductor could effectively maintained the stability of the reaction interface during high-voltage cycling. Meanwhile, bulk Mg and Ti co-doping can mitigate the migration of Ni ions in the bulk to keep the stability of transition metal-oxygen (M-O) bond at deep charging. As a result, the NCM@MTP cathode shows excellent long cycle stability at high-voltage charging, which keep high capacity retention of 89.3% and 84.3% at 1C after 200 and 100 cycles under room and elevated temperature of 25 and 55 °C, respectively. This work provides new insights for manipulating the surface chemistry of electrode materials to suppress the lattice oxygen evolution at high charging voltage.

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A universal ionic liquid solvent for non-halide lead sources in perovskite solar cells Yue Chen, Yamin Xu, Jin Liu, Yuexin Lin, Jianfei Hu, Chensi Cao, Yingdong Xia,Yonghua Chen 2022, 71(8): 445-451.  DOI: 10.1016/j.jechem.2022.03.054 Abstract ( 15 )   PDF (5429KB) ( 7 )   Replacing lead iodide (PbI2) with suitable non-halides lead source has been found to be an effective method to control crystallization and fabricate high-performance perovskite solar cells (PSCs). However, the solubility of non-halide lead sources is highly limited by traditional solvents due to the chemical interaction limitation. Here, we report a series of non-halide lead sources (e.g., lead acetate (PbAc2), lead sulfate (PbSO4), lead carbonate (PbCO3), lead nitrate (Pb(NO3)2), lead formate (Pb(HCOO)2) and lead oxalate (PbC2O4)) can be well dissolved in an ionic liquid solvent methylammonium acetate (MAAc). We found that the universal strong coordination of C=O with lead ion (Pb2+) and the formation of hydrogen bonds were observed in perovskite precursor solution. This allows the dissolution of non-halide lead salts and is able to produce perovskite film with smooth, compact, and full coverage crystal grain. The power conversion efficiency (PCE) of 14.48%, 19.21%, and 20.13% in PSCs based on PbSO4, PbAc2, and PbCO3 was achieved, respectively, in the absence of any additives and passivation agents. This study demonstrates the universality of ionic liquid for the preparation of PSCs based on non-halides lead sources.

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Dynamic phase transition behavior of a LiMn0.5Fe0.5PO4 olivine cathode material for lithium-ion batteries revealed through in-situ X-ray techniques Sujeera Pleuksachat, Phongsit Krabao, Sarawut Pongha, Viyada Harnchana, Pawinee Klangtakai, Wanwisa Limphirat, Siriwat Soontaranon, Jeffrey Nash, Nonglak Meethong 2022, 71(8): 452-459.  DOI: 10.1016/j.jechem.2022.04.016 Abstract ( 18 )   PDF (8469KB) ( 8 )   LiMn0.5Fe0.5PO4 has attracted great interest due to its good electrochemical performance and higher operating voltages. This has led to a greater than 30 percent higher energy density than for commercial LiFePO4 olivine cathodes. Understanding the phase transition behaviors and kinetics of this material will help researchers to design and develop next generation cathodes for Li-ion batteries. In this study, we investigated non-equilibrium phase transition behaviors in a LiMn0.5Fe0.5PO4 cathode material during charge-discharge processes by varying current rates (C-rates) using synchrotron in-situ X-ray techniques. These methods included wide angle X-ray scattering (in-situ WAXS) and X-ray absorption spectroscopy (in-situ XAS). The WAXS spectra indicate that the phase transition of LiMn0.5Fe0.5PO4 material at slow C-rates is induced by a two-phase reaction. In contrast, at a high C-rate (5C), the formation of an intermediate phase upon discharge is clearly observed. Concurrently, the oxidation numbers of the redox reactions of Fe2+/Fe3+ and Mn2+/Mn3+ were evaluated using in-situ XAS. This combination of synchrotron in-situ X-ray techniques gives clear insights into the non-equilibrium phase transition behavior of a LiMn0.5Fe0.5PO4 cathode material. This new understanding will be useful for further developments of this highly promising cathode material for practical commercialization.

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High-efficient solar-driven hydrogen production by full-spectrum synergistic photo-thermo-catalytic methanol steam reforming with in-situ photoreduced Pt-CuOx catalyst Donghui Li, Jie Sun, Rong Ma, Jinjia Wei 2022, 71(8): 460-469.  DOI: 10.1016/j.jechem.2022.04.020 Abstract ( 8 )   PDF (4863KB) ( 3 )   Synergy between the intrinsic photon and thermal effects from full-spectrum sunlight for H2 production is considered to be central to further improve solar-driven H2 production. To that end, the photo-thermo-catalyst that demonstrates both photoelectronic and photothermal conversion capabilities have drawn much attention recently. Here, we propose a novel synergistic full-spectrum photo-thermo-catalysis technique for high-efficient H2 production by solar-driven methanol steam reforming (MSR), along with the Pt-CuOx photo-thermo-catalyst featuring Pt-Cu/Cu2O/CuO heterojunctions by Pt-mediated in-situ photoreduction of CuO. The results show that the H2 production performance rises superlinearly with increasing light intensity. The optimal H2 production rate of 1.6 mol g-1 h-1 with the corresponding solar-to-hydrogen conversion efficiency of 7% and the CO selectivity of 5% is achieved under 15 × sun full-spectrum irradiance (1 × sun = 1 kW m-2) at 180 °C, which is much more efficient than the previously-reported Cu-based thermo-catalysts for MSR normally operating at 250∼350 °C. These attractive performances result from the optimized reaction kinetics in terms of intensified intermediate adsorption and accelerated carrier transfer by long-wave photothermal effect, and reduced activation barrier by short-wave photoelectronic effect, due to the broadened full-spectrum absorbability of catalyst. This work has brought us into the innovative technology of full-spectrum synergistic photo-thermo-catalysis, which is envisioned to expand the application fields of high-efficient solar fuel production.

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Intrinsic electrochemical activity of Ni in Ni3Sn4 anode accommodating high capacity and mechanical stability for fast-charging lithium-ion batteries Janghyuk Moon, Trung Dinh Hoang, Seong Soo Park, Seowan Park, Dong Young Rhee, Junwon Lee, Sang A Han, Min-Sik Park, Jung Ho Kim 2022, 71(8): 470-477.  DOI: 10.1016/j.jechem.2022.03.006 Abstract ( 7 )   PDF (2732KB) ( 2 )   Fast interfacial kinetics derived from bicontinuous three-dimensional (3D) architecture is a strategic feature for achieving fast-charging lithium-ion batteries (LIBs). One of the main reasons is its large active surface and short diffusion path. Yet, understanding of unusual electrochemical properties still remain great challenge due to its complexity. In this study, we proposed a nickel-tin compound (Ni3Sn4) supported by 3D Nickel scaffolds as main frame because the Ni3Sn4 clearly offers a higher reversible capacity and stable cycling performance than bare tin (Sn). In order to verify the role of Ni, atomic-scale simulation based on density functional theory systematically addressed to the reaction mechanism and structural evolution of Ni3Sn4 during the lithiation process. Our findings are that Ni enables Ni3Sn4 to possess higher mechanical stability in terms of reactive flow stress, subsequently lead to improve Li storage capability. This study elucidates an understanding of the lithiation mechanism of Ni3Sn4 and provides a new perspective for the design of high-capacity and high-power 3D anodes for fast-charging LIBs.

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Stress-assisted design of stiffened graphene electrode structure toward compact energy storage Yuzuo Wang, Jing Chen, Huasong Qin, Ke Chen, Zhuangnan Li, Yan Chen, Juan Li, Tianzhao Hu, Shaorui Chen, Zhijun Qiao, Dianbo Ruan, Quanhong Yang, Yilun Liu, Feng Li 2022, 71(8): 478-487.  DOI: 10.1016/j.jechem.2022.04.028 Abstract ( 7 )   PDF (7387KB) ( 2 )   The low spatial charge-storage density of porous carbons greatly limits volumetric performance in electrochemical capacitors. An increase of charge-storage density requires structural refinements to balance the trade-offs between the porosity and density of materials, but the limited mechanical properties of carbons usually fail to withstand effective densifying processes and obtain an ideal pore structure. Herein, we design the stiffened graphene of superior bending rigidity, enabling the fine adjustments of pore structure to maximize the volumetric capacitance for the graphene-based electrodes. The in-plane crumples on graphene sheets are found to contribute largely to the bending rigidity, which is useful to control the structural evolution and maintain sufficient ion-accessible surface area during the assembling process. This makes the capacitance of stiffening activated graphene keep 98% when the electrode density increases by 769% to reach 1.13 g cm-3 after mechanical pressure, an excellent volumetric energy density of 98.7 Wh L-1 in an ionic-liquid electrolyte is achieved. Our results demonstrate the role of intrinsic material properties on the performance of carbon-based electrodes for capacitive energy storage.

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Direct observation of the CO2 formation and C-H consumption of carbon electrode in an aqueous neutral electrolyte supercapacitor by in-situ FTIR and Raman Murilo M. Amaral, Victor Y. Yukuhiro, Rafael Vicentini, Alfredo C. Peterlevitz, Leonardo M.Da Silva, Pablo Fernandez, Hudson Zanin 2022, 71(8): 488-496.  DOI: 10.1016/j.jechem.2022.03.020 Abstract ( 7 )   PDF (6255KB) ( 2 )   Electrical double-layer capacitors (EDLCs) consist of energy storage devices that present high-power and moderate energy density. The electrolyte and electrode physicochemical properties are crucial for improving their overall energy storage capabilities. Therefore, the stability of the EDLCs' materials is the primary focus of this study. Since energy storage depends on the specific capacitance, and also on the square of the maximum capacitive cell voltage (UMCV). Thus, electrodes with high specific surface area (SSA) and electrolytes with excellent electrochemical stability are commonly reported in the literature. Aqueous electrolytes are safer and green devices compared to other organic-based solutions. On the other hand, their UMCV is reduced compared to other electrolytes (e.g., organic-based and ionic liquids). In this sense, spanning the UMCV for aqueous-based electrolytes is a ‘hot topic' research. Unfortunately, the lack of protocols to establish reliable UMCV values has culminated in the publishing of several conflicting results. Herein, we confirm that multiwalled carbon nanotubes (MWCNTs) housed in cells degrade and produce CO2 under abusive polarisation conditions. It is probed by employing electrochemical techniques, in-situ FTIR and in-situ Raman spectroscopies. From these considerations, the current study uses spectro-electrochemical techniques to support the correct determination of the electrode and electrolyte stability conditions as a function of the operating electrochemical parameters.

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High-performance proton exchange membrane fuel cell with ultra-low loading Pt on vertically aligned carbon nanotubes as integrated catalyst layer Qing Hao Meng,Chao Hao, Bowen Yan, Bin Yang,Jia Liu Pei Kang Shen, Zhi Qun Tian 2022, 71(8): 497-506.  DOI: 10.1016/j.jechem.2022.03.018 Abstract ( 15 )   PDF (11878KB) ( 4 )   Reducing a Pt loading with improved power output and durability is essential to promote the large-scale application of proton exchange membrane fuel cells (PEMFCs). To achieve this goal, constructing optimized structure of catalyst layers with efficient mass transportation channels plays a vital role. Herein, PEMFCs with order-structured cathodic electrodes were fabricated by depositing Pt nanoparticles by E-beam onto vertically aligned carbon nanotubes (VACNTs) growth on Al foil via plasma-enhanced chemical vapor deposition. Results demonstrate that the proportion of hydrophilic Pt-deposited region along VACNTs and residual hydrophobic region of VANCTs without Pt strongly influences the cell performance, in particular at high current densities. When Pt nanoparticles deposit on the top depth of around 600 nm on VACNTs with a length of 4.6 μm, the cell shows the highest performance, compared with others with various lengths of VACNTs. It delivers a maximum power output of 1.61 W cm-2 (H2/O2, 150 kPa) and 0.79 W cm-2 (H2/Air, 150 kPa) at Pt loading of 50 μg cm-2, exceeding most of previously reported PEMFCs with Pt loading of < 100 μg cm-2. Even though the Pt loading is down to 30 μg cm-2 (1.36 W cm-2), the performance is also better than 100 μg cm-2 (1.24 W cm-2) of commercial Pt/C, and presents better stability. This excellent performance is critical attributed to the ordered hydrophobic region providing sufficient mass passages to facilitate the fast water drainage at high current densities. This work gives a new understanding for oxygen reduction reaction occurred in VACNTs-based ordered electrodes, demonstrating the most possibility to achieve a substantial reduction in Pt loading <100 μg cm-2 without sacrificing in performance.

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Cost projections for microwave plasma CO production using renewable energy Remko J. Detz, Bobvan der Zwaan 2022, 71(8): 507-513.  DOI: 10.1016/j.jechem.2022.04.014 Abstract ( 4 )   PDF (1251KB) ( 2 )   Successful deployment of renewable fuel production requires substantial cost reduction along the entire value chain of the underlying manufacturing routes. To improve their performance, renewable fuel production technologies should follow a cost-reducing learning curve. In this article, we adopt recent evidence that learning-by-doing is directly influenced by the technology unit size and explore three scenarios for microwave plasma CO2 conversion in which the learning rate varies between 10%, 15%, and 20%. Our projections reveal that the total investments required to deploy this CO2 conversion technology at an exajoule scale decline from 83 down to 23 billion euros under a 10% increase in the value of the learning rate. The CO production costs in 2050 amount to 247-346 €(2019)/tCO, in which the range is determined by the value of the learning rate. Even under substantial learning until 2050 the levelized CO production cost is unlikely to become competitive with conventional natural gas-based CO production processes, except when a CO2 tax is applied of up to 150 €(2019)/tCO2. To optimally exploit effects of learning-by-doing, we recommend developing several CO production technologies simultaneously with multiple unit sizes, so as to improve the chance of ultimately selecting the process with the highest learning rate.

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Dynamic surface restructuring of nanoporous Cu2-xSe for efficient CO2 electroreduction into methanol Xin Lin, Xunlin Liu, Yang Zhao, Jiao Lan, Kang Jiang, Zhixiao Liu, Feng Xie, Yongwen Tan 2022, 71(8): 514-520.  DOI: 10.1016/j.jechem.2022.03.032 Abstract ( 11 )   PDF (7770KB) ( 10 )

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High-temperature deoxygenation-created highly porous graphitic carbon nanosheets for ultrahigh-rate supercapacitive energy storage Xuan Wang, Shanyong Chen, Chang Liu, Yi Yu, Mingjiang Xie, Xuefeng Guo 2022, 71(8): 521-527.  DOI: 10.1016/j.jechem.2022.03.051 Abstract ( 7 )   PDF (6791KB) ( 3 )   Developing carbon-based supercapacitors with high rate capability is of great importance to meet the emerging demands for devices that requires high energy density as well as high power density. However, it is hard to fabricate a nanocarbon with high electro-active surface area meanwhile maintaining superior conductivity to ensure the high rate capability since excellent conductivity is usually realized by high temperature graphitization, which would lead to the structural collapse and sintering resulting in low surface area. Herein, we reported a highly porous graphitic carbon nanosheet with an unprecedented rate capability of 98% of its initial capacitance from 0.5 to 50 A/g for ultrahigh-rate supercapacitive energy storage. These hierarchical mesoporous carbon nanosheets (HMCN) were fabricated by a template induced catalytic graphitization approach, in which sheet-like Mg(OH)2 was employed as catalytic template in situ catalytically polymerizing of catechol and formaldehyde and catalytically graphitizing of the formed carbon skeleton. Upon the co-effect of template (avoiding the sintering) and the deoxygenation (creating the pores) during the high temperature graphitization process, the obtained HMCN material possesses nanosheet morphology with highly porous graphitic microstructure rich in mesoporosity, large in surface area (2316 m2/g), large in pore volume (3.58 cm3/g) and excellent in conductivity (109.8 S/cm). In 1.0 M TEABF4/AN, HMCN exhibits superior supercapacitive performance including large energy density of 52.2 Wh/kg at high power density of 118 kW/kg, long-cycling stability and excellent rate capability, making HMCN a promising electrode material for supercapacitor devices.

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Hybridization of iron phthalocyanine and MoS2 for high-efficiency and durable oxygen reduction reaction Haibing Meng, Xiaolong Liu, Xiao Chen, Ying Han, Chenhui Zhou, Qinyuan Jiang, Ting Tan, Rufan Zhang 2022, 71(8): 528-538.  DOI: 10.1016/j.jechem.2022.04.031 Abstract ( 8 )   PDF (4815KB) ( 2 )   Hybrid catalysts based on iron phthalocyanine (FePc) have raised much attention due to their promising applications in electrocatalytic oxygen reduction reaction (ORR). Various hybridization strategies have been developed for improving their activity and durability. However, the influence of different hybridization strategies on their catalytic performance remains unclear. In this study, FePc was effectively distributed on molybdenum disulfide (MoS2) forming FePc-based hybrid catalysts, namely FePc-MoS2, FePc*-MoS2, and FePc-Py-MoS2, respectively, to disclose the related influence. Through direct hybridization, the stacked and highly dispersed FePc on MoS2 resulted in FePc-MoS2, and FePc*-MoS2, respectively, in which the substrate and FePc are mainly bound through van der Waals interactions. Through covalent hybridization strategy using pyridyl (Py) as a linker, FePc-Py-MoS2 hybrid catalyst was prepared. Experimental and theoretical results disclosed that the linker hybridization of FePc and MoS2 facilitated the exposure of Fe-N4 sites, maintained the intrinsic activity of FePc by forming a more dispersed phase and increased the durability via Fe-N bonding, rendering the FePc-Py-MoS2 an excellent ORR hybrid catalyst. Compared with van der Waals hybridized FePc-MoS2 and FePc*-MoS2 in alkaline media, the linker hybridized FePc-Py-MoS2 showed an obviously enhanced ORR activity with a half-wave potential (E1/2) of 0.88 V vs RHE and an ultralow Tafel slope of 26 mV dec-1. Besides, the FePc-Py-MoS2 exhibited a negligible decay of E1/2 after 50,000 CV cycles for ORR, showing its superior durability. This work gives us more insight into the influence of different hybrid strategies on FePc catalysts and provides further guidance for the development of highly efficient and durable ORR catalysts.

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Artificial solid electrolyte interface layer based on sodium titanate hollow microspheres assembled by nanotubes to stabilize zinc metal electrodes Minfeng Chen, Weijun Zhou, Qinghua Tian, Xiang Han, Yanjun Tan, Jizhang Chen, Ching-Ping Wong 2022, 71(8): 539-546.  DOI: 10.1016/j.jechem.2022.03.026 Abstract ( 9 )   PDF (11231KB) ( 5 )   Recently, aqueous zinc-ion batteries with intrinsic safety, low cost, and environmental benignity have attracted tremendous research interest. However, zinc dendrites, harmful side reactions, and zinc metal corrosion stand in the way. Herein, we use lepidocrocite-type sodium titanate hollow microspheres assembled by nanotubes to constitute an artificial solid electrolyte interface layer on the zinc metal electrode. Thanks to the hierarchical structure with abundant open voids, negative-charged layered framework, low hydrophilicity, electrically insulting nature, and large ionic conductivity, the sodium titanate coating layer can effectively homogenize the electric field, promote the Zn2+ ion transfer, guide the Zn2+ ion flux, reduce the desolvation barrier, improve the exchange current density, and accommodate the plated zinc metal. Consequently, this coating layer can effectively suppress zinc dendrites and other unfavorable effects. With this coating layer, the Zn//Zn symmetric cell is able to provide an impressive cumulative zinc plating capacity of 1375 mAh cm-2 at a current density of 5 mA cm-2. This coating layer also contributes to significantly improved electrochemical performances of Zn//MnO2 battery and zinc-ion hybrid capacitor. This work offers new insights into the modifications of zinc metal electrodes.

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Optimizing the oxide support composition in Pr-doped CeO2 towards highly active and selective Ni-based CO2 methanation catalysts Anastasios I. Tsiotsias, Nikolaos D. Charisiou, Ayesha Al Khoori, Safa Gaber, Vlad Stolojan, Victor Sebastian, Bartvan der Linden, Atul Bansode, Steven J. Hinder, Mark A. Baker, Kyriaki Polychronopoulou, Maria A. Goula 2022, 71(8): 547-561.  DOI: 10.1016/j.jechem.2022.04.003 Abstract ( 5 )   PDF (15356KB) ( 2 )   In this study, Ni catalysts supported on Pr-doped CeO2 are studied for the CO2 methanation reaction and the effect of Pr doping on the physicochemical properties and the catalytic performance is thoroughly evaluated. It is shown, that Pr3+ ions can substitute Ce4+ ones in the support lattice, thereby introducing a high population of oxygen vacancies, which act as active sites for CO2 chemisorption. Pr doping can also act to reduce the crystallite size of metallic Ni, thus promoting the active metal dispersion. Catalytic performance evaluation evidences the promoting effect of low Pr loadings (5 at% and 10 at%) towards a higher catalytic activity and lower CO2 activation energy. On the other hand, higher Pr contents negate the positive effects on the catalytic activity by decreasing the oxygen vacancy population, thereby creating a volcano-type trend towards an optimum amount of aliovalent substitution.

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Photocatalytic dry reforming of methane by rhodium supported monoclinic TiO2-B nanobelts Masaru Kushida,Akira Yamaguchi, Masahiro Miyauchi 2022, 71(8): 562-571.  DOI: 10.1016/j.jechem.2022.04.022 Abstract ( 3 )   PDF (5184KB) ( 2 )   The conversion of methane and carbon dioxide into syngas (dry reforming of methane; DRM) has attracted attention owing to the potential to reuse greenhouse gases. Titanium dioxide (TiO2)-based photocatalysts, which have been widely commercialized owing to their high efficiency, non-toxicity, and low cost, are strongly desired in DRM. Here, we report a monoclinic-phase TiO2-B nanobelts-supported rhodium (Rh/TiO2-B nanobelts) catalyst that efficiently promotes DRM under ultraviolet light irradiation at low temperatures. Photogenerated holes in the TiO2-B nanobelts were used to oxidize methane, while the electrons were trapped in rhodium to reduce carbon dioxide. Rh/TiO2-B nanobelts exhibited considerably higher durability and activity than Rh-loaded conventional TiO2 (anatase and rutile), owing to the lattice and/or surface oxygen reactivity in TiO2-B nanobelts, which was suggested by X-ray photoelectron spectroscopy measurements and photocatalytic performance tests under an atmosphere of methane alone. This study paves the path for the effective utilization of methane by constructing active TiO2-based nanometal photocatalysts.

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Nitrogen-rich azoles as trifunctional electrolyte additives for high-performance lithium-sulfur battery Dan-Yang Wang, Wenmin Wang, Fengli Li, Xin Li, Wei Guo, Yongzhu Fu 2022, 71(8): 572-579.  DOI: 10.1016/j.jechem.2022.04.032 Abstract ( 5 )   PDF (4015KB) ( 3 )   Rechargeable lithium-sulfur (Li-S) batteries are considered one of the most promising energy storage techniques owing to the high theoretical energy density. However, challenges still remain such as the shuttle effect of lithium polysulfides (LPSs) and the instability of lithium metal anode. Herein, we propose to use nitrogen-rich azoles, i.e., triazole (Ta) and tetrazole (Tta), as trifunctional electrolyte additives for Li-S batteries. The azoles afford strong lithiophilicity for the chemisorption of LPSs. The density functional theory and experimental analysis verify the presence of Li bonds between the azoles and LPSs. The azoles can also interact with lithium salt in the electrolyte, leading to increase ionic conductivity and lithium-ion transference number. Moreover, the azoles render particle-like lithium deposition on the lithium metal anode, leading to superlong cycling of a Li symmetric cell. The Li-S batteries with Ta and Tta exhibit the initial discharge capacity of 1425.5 and 1322.2 mAh g-1, respectively, at 0.2C rate, and promising cycling stability. They also enable enhanced cycling performance of a Li-organosulfide battery.

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Boosting the oxygen evolution reaction performance of wrinkled Mn(OH)2 via conductive activation with a carbon binder Kahyun Ham, Jaewon Lee, Kiyoung Lee, Jaeyoung Lee 2022, 71(8): 580-587.  DOI: 10.1016/j.jechem.2022.04.034 Abstract ( 7 )   PDF (5676KB) ( 3 )   Electrochemical water splitting is one of the most reliable approaches for environmental-friendly hydrogen production. Because of their stability and abundance, Mn-based materials have been studied as electrocatalysts for the oxygen evolution reaction (OER), which is a more sluggish reaction in the water splitting system. To increase the OER activity of Mn, it is imperative to facilitate the structural change of Mn oxide to the active phase with Mn3+ species, known as the active site. Here, we present the relationship between the electronic conductivity in the catalyst layer and the formation of the Mn active phase, δ-MnO2, from wrinkled Mn(OH)2. Mn(OH)2 has poor conductivity, and it disrupts the oxidation reaction toward MnOOH or δ-MnO2. Adjacent conductive carbon to Mn(OH)2 enabled Mn(OH)2 to be oxidized to δ-MnO2. Furthermore, after repetitive cyclic voltammetry activation, the more conductive environment resulted in a higher density of δ-MnO2 through the irreversible phase transition, and thus it contributes to the improvement of the OER activity.

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B-doped and La4NiLiO8-coated Ni-rich cathode with enhanced structural and interfacial stability for lithium-ion batteries Lingjun Li, Lizhi Fu, Miao Li, Chu Wang, Zixiang Zhao, Shangchen Xie, Haichen Lin, Xianwen Wu, Haodong Liu, Li Zhang, Qiaobao Zhang, Lei Tan 2022, 71(8): 588-594.  DOI: 10.1016/j.jechem.2022.04.037 Abstract ( 10 )   PDF (7320KB) ( 8 )   Ni-rich layered oxides are considered promising cathodes for advanced lithium-ion batteries (LIBs) in the future, owing to their high capacity and low cost. However, the issues on structural and interfacial stability of Ni-rich cathodes still pose substantial obstacles in the practical application of advanced LIBs. Here, we employ a one-step method to synthesize a B-doped and La4NiLiO8-coated LiNi0.825Co0.115Mn0.06O2 (BL-1) cathode with reliable structure and interface, for the first time. The La4NiLiO8 coating layer can prevent cathodes from electrolyte assault and facilitate Li+ diffusion kinetics. Moreover, B-doping can effectively restrain the pernicious H2-H3 phase transition and adjust the orientation of primary particles to a radial alignment, which is obstructive to the arise of microcracks induced by the change of anisotropic volume. Specifically, when tested in pouch cells, the BL-1cathode exhibits outstanding capacity retention of 93.49% after 500 cycles at 1C. This dual-modification strategy dramatically enhances the stability of the structure and interface for Ni-rich cathode materials, consequently accelerating the commercialization process of high-energy-density LIBs.

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An in-situ generated Bi-based sodiophilic substrate with high structural stability for high-performance sodium metal batteries Lulu Li, Ming Zhu, Guanyao Wang, Fangfang Yu, Liaoyong Wen, Hua-Kun Liu, Shi-Xue Dou, Chao Wu 2022, 71(8): 595-603.  DOI: 10.1016/j.jechem.2022.04.019 Abstract ( 9 )   PDF (6287KB) ( 4 )   Sodium (Na) metal anode exhibits a potential candidate in next-generation rechargeable batteries owing to its advantages of high earth abundance and low cost. Unfortunately, the practical development of sodium metal batteries is inherently plagued by challenges such as the side reactions and the growth of Na dendrites. Herein we report a highly stable Bi-based “sodiophilic” substrate to stabilize Na anode, which is created by in-situ electrochemical reactions of 3D hierarchical porous Bi2MoO6 (BMO) microspheres. BMO is initially transformed into the Bi “nanoseeds” embedded in the Na-Mo-O matrix. Subsequently, the Bi nanoseeds working as preferential nucleation sites through the formation of Bi-Na alloy enable the non-dendritic Na deposition. The asymmetric cells based on such BMO-based substrate can deliver a long-term cycling for 600 cycles at a large capacity of 4 mAh cm-2and for 800 cycles at a high current density of 10 mA cm-2. Even at a high depth of discharge (66.67%), the Na-predeposited BMO (Na@BMO) electrodes can cycle for more than 1600 h. The limited Na@BMO anodes coupled with the Na3V2(PO4)3 cathodes (N/P ratio of 3) in full cells also show excellent electrochemical performance with a capacity retention of about 97.4% after 1100 cycles at 2 C.

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Enhanced efficiency and stability in Sn-based perovskite solar cells by trimethylsilyl halide surface passivation Zheng Zhang, Liang Wang, Ajay Kumar Baranwal, Shahrir Razey Sahamir, Gaurav Kapil, Yoshitaka Sanehira, Muhammad Akmal Kamarudin, Kohei Nishimura, Chao Ding, Dong Liu, Yusheng Li, Hua Li, Mengmeng Chen, Qing Shen, Teresa S. Ripolles, Juan Bisquert, Shuzi Hayase 2022, 71(8): 604-611.  DOI: 10.1016/j.jechem.2022.03.028 Abstract ( 8 )   PDF (7554KB) ( 4 )   Lead free tin perovskite solar cells (PKSCs) are the most suitable alternative candidate for conventional lead perovskite solar cells. However, the efficiency and the stability are insufficient, mainly because of the poor film quality and numerous defects. Here we introduce an efficient strategy based on a simple trimethylsilyl halide surface passivation to increase the film quality and reduce the defect density. At the same time, a hydrophobic protective layer on the perovskite surface is formed, which enhanced the PKSCs' stability. The efficiency of the solar cell after the passivation was enhanced from 10.05 % to 12.22% with the improved open-circuit voltage from 0.57 V to 0.70 V. In addition, after 92 days of storage in N2 filled glovebox, the modified T-PKSCs demonstrated high stability maintaining 80% of its initial efficiency. This work provides a simple and widely used strategy to optimize the surface/interface optoelectronic properties of perovskites for giving more efficient and stable solar cells and other optoelectronic devices.

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Dry electrode technology for scalable and flexible high-energy sulfur cathodes in all-solid-state lithium-sulfur batteries Jiang-Kui Hu, Hong Yuan, Shi-Jie Yang, Yang Lu, Shuo Sun, Jia Liu, Yu-LongLiao, Shuai Li, Chen-Zi Zhao, Jia-Qi Huang 2022, 71(8): 612-618.  DOI: 10.1016/j.jechem.2022.04.048 Abstract ( 64 )   PDF (5037KB) ( 32 )   All-solid-state lithium-sulfur batteries (ASSLSBs) employing sulfide solid electrolytes are one of the most promising next-generation energy storage systems due to their potential for higher energy density and safety. However, scalable fabrication of sheet-type sulfur cathodes with high sulfur loading and excellent performances remains challenging. In this work, sheet-type freestanding sulfur cathodes with high sulfur loading were fabricated by dry electrode technology. The unique fibrous morphologies of polytetrafluoroethylene (PTFE) binders in dry electrodes not only provides excellent mechanical properties but also uncompromised ionic/electronic conductance. Even employed with thickened dry cathodes with high sulfur loading of 2 mg cm-2, ASSLSBs still exhibit outstanding rate performance and cycle stability. Moreover, the all-solid-state lithium-sulfur monolayer pouch cells (9.2 mAh) were also demonstrated and exhibited excellent safety under a harsh test situation. This work verifies the potential of dry electrode technology in the scalable fabrication of thickened sulfur cathodes and will promote the practical applications of ASSLSBs.

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Charge redistribution caused by sulfur doping of bimetal FeCo phosphides supported on heteroatoms-doped graphene for Zn-air batteries with stable cycling Jin-Tao Ren, Yi-Dai Ying, Yu-Ping Liu, Wei Li, Zhong-Yong Yuan 2022, 71(8): 619-630.  DOI: 10.1016/j.jechem.2022.03.048 Abstract ( 4 )   PDF (14843KB) ( 1 )   Exploring feasible synthesis approaches to highly efficient and robust bifunctional electrocatalysts toward both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is triggering researcher's even-increasing interest in rechargeable Zn-air batteries. Herein, sulfur-doped bimetal FeCo phosphide nanoparticles dispersed on N,P,S-tri-doped graphene (donated as S-FeCo3P/NPSG) are rationally prepared through a controllable one-step carbothermal-phosphorization strategy. The modified charge distribution and electron-donor properties of S-FeCo3P/NPSG caused by S decoration render a significantly beneficial effect on the electrocatalytic activities. Consequently, the S-FeCo3P/NPSG electrode exhibits extraordinary bifunctional activities toward oxygen electrochemistry of the OER overpotential of 290 mV at 10 mA cm-2 and the ORR half-wave potential of 0.83 V, approaching to that of noble-metal IrO2 (289 mV) and Pt/C (0.84 V), respectively, but with more stronger operation stability in alkaline media. When S-FeCo3P/NPSG serves as the air cathode for liquid-state Zn-air battery, the large peak power density and energy density, as well as superb discharge-charge durability (cycling life > 600 h) of this device are obtained. Furthermore, all-solid-state Zn-air battery with S-FeCo3P/NPSG as air electrode also displays excellent mechanical flexibility, high power density and stable cycling stability. The self-reconstruction behavior of the S-FeCo3P/NPSG cathode catalysts is also investigated during the electrocatalytic Zn-air battery operation. This work would provide some novel inspiration from aspects of bonding and charge distribution for the rational construction of active and cost-efficient bifucntional oxygen electrocatalysts for energy storage and conversion devices.

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Non-conjugated terpolymer acceptors for highly efficient and stable lager-area all-polymer solar cells Jiabin Liu, Jinliang Liu, Jiawei Deng, Bin Huang, Jiyeon Oh, Lin Zhao, Liang Liu, Changduk Yang, Dong Chen, Feiyan Wu, Lie Chen 2022, 71(8): 631-638.  DOI: 10.1016/j.jechem.2022.03.050 Abstract ( 6 )   PDF (5374KB) ( 2 )   All-polymer solar cells (all-PSCs) have made significant progress recently, but few studies have been conducted to investigate the lab-to-manufacturing translation from the spin-coating method to the printing process. Here, the random copolymerization method and non-conjugated backbone approach are integrated to manipulate the morphology and photoelectric properties of the active layer for large-area printed all-PSCs. A series of non-conjugated terpolymer acceptors PYSe-TC6T(x) (x = 5, 10, and 20, refers to the molar ratio of TC6T unit) are developed by covalently introducing non-conjugated unit TC6T into the PYSe host bipolymer by random copolymerization. The spin-coated PYSe-TC6T(10)-based all-PSC demonstrates the best power conversion efficiency (PCE) of 13.54%, superior to the PYSe-based one (12.45%). More intriguingly, morphological studies reveal that a combination of the random polymerization and non-conjugated backbone strategy can effectively prevent the active layer from over-aggregation and improve the film quality during the printing process, thereby minimizing the efficiency and technology gap between spin-coated small-area devices and blade-coated large-area devices. By directly using the same preparation condition of spin-coating, the blade-coated small-area (0.04 cm2) delivers a PCE of 12.83% and the large-area (1.21 cm2) device achieves a PCE of 11.96% with a small PCE loss. Both PCE value and PCE loss are one of the most outstanding performances of the blade-coated all-PSCs. These findings reveal that a combination of the non-conjugated flexible backbone with random copolymerization to develop non-conjugated terpolymers is an attractive design concept to smoothly realize the lab-to-manufacturing translation.

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Controllable oxygen vacancies and morphology engineering: Ultra-high HER/OER activity under base-acid conditions and outstanding antibacterial properties Hongyao Xue, Alan Meng, Tongqing Yang, Zhenjiang Li, Chunjun Chen 2022, 71(8): 639-651.  DOI: 10.1016/j.jechem.2022.04.052 Abstract ( 9 )   PDF (15959KB) ( 3 )   Introducing vacancy defects and unique morphology is an effective strategy to improve the catalytic performance of transition metal compounds. However, precisely controlling the amount of vacancy defects remains challenging. Here, we propose a facile and efficient hydrothermal accompanying an annealing method to synthesize a series of Mn-doped CoO nanomaterials with controllable oxygen vacancies and unique morphology. The oxygen vacancies amount can be precisely controlled by adjusting the Mn-doping content and is positively correlated with catalytic performance. It was found that the oxygen vacancies amount can reach up to 38.2% over the Mn-doped CoO nanomaterials, resulting in ultra-high hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalytic activity (HER: 25.6 and 37 mV at 10 mA cm-2; OER: 301 and 322 mV at 50 mA cm-2) under both basic and acidic conditions, while reaching 10 mA cm-2 for an ultra-low cell voltage of only 1.52 V, which exceeds that of Pt/C/RuO2 and all reported non-noble metal oxide catalysts. The DFT calculations reveal oxygen vacancies can optimize H* and HOO* intermediates adsorption free energy, thus improving the HER and OER performance. Interestingly, the Mn-doped CoO with rich oxygen vacancies exhibits excellent antibacterial properties in vitro of biomedicine. This work provides new ideas and methods for the rational design and precise control of vacancy defects in transition metal compounds and explores their potential application value in electrochemical water splitting and biomedical fields.

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Corrigendum to “MXene-coated silk-derived carbon cloth toward flexible electrode for supercapacitor application” [J. Energy. Chem. 27 (2018) 161-166] Minmin Hu, Tao Hu, Renfei Cheng, Jinxing Yang, Cong Cui, Chao Zhang, Xiaohui Wang 2022, 71(8): 652-654.  DOI: 10.1016/j.jechem.2022.01.043 Abstract ( 16 )   PDF (4068KB) ( 7 )

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Corrigendum to “Cation-vacancy induced Li+ intercalation pseudocapacitance at atomically thin heterointerface for high capacity and high power lithium-ion batteries” [J. Energy Chem. 62 (2021) 281-288] Ding Yuan, David Adekoya, Yuhai Dou, Yuhui Tian, Hao Chen, Zhenzhen Wu, Jiadong Qin, Linping Yu, Jian Zhang, Xianhu Liu, Shi Xue Dou, Shanqing Zhang 2022, 71(8): 655-656.  DOI: 10.1016/j.jechem.2021.11.037 Abstract ( 4 )   PDF (5860KB) ( 3 )

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Corrigendum to “Monitoring dynamics of defects and single Fe atoms in N-functionalized few-layer graphene by in situ temperature programmed scanning transmission electron microscopy” [JECHEM 64 (2022) 520-530] Rosa Arrigo, Takeo Sasaki, June Callison, Diego Gianolio, Manfred Erwin Schuster 2022, 71(8): 657-657.  DOI: 10.1016/j.jechem.2021.08.003 Abstract ( 2 )   PDF (128KB) ( 2 )

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Corrigendum to “Rearrangement on surface structures by boride to enhanced cycle stability for LiNi0.80Co0.15Al0.05O2 cathode in lithium ion batteries” [J. Energy. Chem. 45 (2020) 110-118] Shubiao Xia, Wenjin Huang, Xiang Shen, Jiaming Liu, Feixiang Cheng, Jian-Jun Liu, Xiaofei Yang, Hong Guo 2022, 71(8): 658-658.  DOI: 10.1016/j.jechem.2022.04.044 Abstract ( 4 )   PDF (128KB) ( 2 )