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2022, Vol. 69, No. 6　Online: 15 June 2022

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Ultrahigh-rate and high-frequency MXene micro-supercapacitors for kHz AC line-filtering Xin Feng, Sen Wang, Pratteek Das, Xiaoyu Shi, Shuanghao Zheng, Feng Zhou, Jing Ning, Dong Wang, Jincheng Zhang, Yue Hao, Zhong-Shuai Wu 2022, 69(6): 1-8.  DOI: 10.1016/j.jechem.2021.11.012 Abstract ( 12 )   PDF (6295KB) ( 6 )   Harnessing energy from the environment promotes the rapid development of micro-power generators and relevant power management modules of alternating current (AC) line-filtering to obtain a stabilized direct current (DC) output for storage and use. Micro-supercapacitors (MSCs) with miniaturized volume and high-frequency response are regarded as a critical component in filtering circuits for microscale power conversion. Here, we reported the fabrication of the wafer-sized planar MSCs (M-MSCs) based on 2D Ti3C2Tx MXene using a photolithography technique. The M-MSCs exhibited an areal capacitance of 153 lF cm-2 and a frequency characteristic (f0) of 5.6 kHz in aqueous electrolyte. Moreover, by employing suitable ionic liquid as electrolyte, the voltage window was expanded to 2 V and the f0 could be pushed to 6.6 kHz relying on the electrical double-layer mechanism and lower adsorption energy while maintaining quasi-rectangular cyclic voltammogram curves at 5000 V s-1. Furthermore, the inte-grated MSCs pack was constructed and exhibited excellent rectifying ability by filtering various high-frequency 5000 Hz AC signals with different waveforms into stable DC outputs. Such ultrahigh-rate and high-voltage M-MSCs module for kHz AC line-filtering would be potentially integrated with cus-tomizable electronics to realize on-chip rectifiers in high-density integrated circuit.

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Hierarchical CoNi-LDH nanosheet array with hydrogen vacancy for high-performance aqueous battery cathode Wang Qiao, Bowen Jin, Wenfu Xie, Mingfei Shao, Min Wei 2022, 69(6): 9-15.  DOI: 10.1016/j.jechem.2021.09.012 Abstract ( 10 )   PDF (7361KB) ( 3 )   Aqueous rechargeable multiple metal-ion storage battery (ARSB) has a large potential in energy storage devices due to their safe usage, low cost and high rate capability. Nevertheless, the performance of prac-tical ARSB is largely restricted by low capacity and limited cathode materials. Herein, we demonstrate an efficient cathode material based on CoNi-layered double hydroxide (LDH) nanosheets arrays with abun-dant hydrogen vacancy induced by electrochemical activation process for high performance of cations storage. Consequently, the electrochemical activated CoNi-LDH (ECA-CoNi-LDH) nanosheets arrays exhi-bit high metal ion (Li+, Na+, Zn2+, Mg2+ and Ca2+) storage capacities, which is 9 times and 3 times higher that of unactivated CoNi-LDH arrays and ECA-CoNi-LDH without hierarchical structure, respectively. Moreover, the ECA-CoFe-LDH also shows the possibility for practical applications in actual batteries. By coupling with a Fe2O3/C anode, the assembled aqueous battery delivered a large energy density of 184.4 Wh kg-1 at power density of 4 Wh kg-1 in high voltage range of 0-2 V. To our best knowledge, such high energy density and large working window of our assembled aqueous battery is exceeded other LDH-based aqueous battery or supercapacitor, and the energy density almost comparable than that of com-mercial Li-ion batteries. Moreover, almost no measurable capacitance losses can be detected even after 10000 cycles. In addition, this work also provides a strategy to develop a high energy density cathode for multiple metal-ion storage batteries.

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Revisiting the capacity-fading mechanism of P2-type sodium layered oxide cathode materials during high-voltage cycling Meidan Jiang, Guannan Qian, Xiao-Zhen Liao, Zhouhong Ren, Qingyu Dong, Dechao Meng, Guijia Cui, Siqi Yuan, Sang-Jun Lee, Tian Qin, Xi Liu, Yanbin Shen, Yu-Shi He, Liwei Chen, Yijin Liu, Linsen Li, Zi-Feng Ma 2022, 69(6): 16-25.  DOI: 10.1016/j.jechem.2022.01.010 Abstract ( 14 )   PDF (10428KB) ( 4 )   P2-type sodium layered oxide cathode (Na2/3Ni1/3Mn2/3O2, P2-NNMO) has attracted great attention as a promising cathode material for sodium ion batteries because of its high specific capacity. However, this material suffers from a rapid capacity fade during high-voltage cycling. Several mechanisms have been proposed to explain the capacity fade, including intragranular fracture caused by the P2-O2 phase tran-sion, surface structural change, and irreversible lattice oxygen release. Here we systematically investi-gated the morphological, structural, and chemical changes of P2-NNMO during high-voltage cycling using a variety of characterization techniques. It was found that the lattice distortion and crystal-plane buckling induced by the P2-O2 phase transition slowed down the Na-ion transport in the bulk and hin-dered the extraction of the Na ions. The sluggish kinetics was the main reason in reducing the accessible capacity while other interfacial degradation mechanisms played minor roles. Our results not only enabled a more complete understanding of the capacity-fading mechanism of P2-NNMO but also revealed the underlying correlations between lattice doping and the moderately improved cycle performance.

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Ion-exchange-induced Bi and K dual-doping of TiOx in molten salts for high-performance electrochemical nitrogen reduction Hao Li, Liqun Wang, Nan Li, Jianmin Feng, Feng Hou, Sihui Wang, Ji Liang 2022, 69(6): 26-34.  DOI: 10.1016/j.jechem.2022.01.002 Abstract ( 8 )   PDF (7679KB) ( 2 )   Electrocatalytic nitrogen reduction reaction (eNRR) at the ambient conditions is attractive for ammonia (NH3) synthesis due to its energy-efficient and eco-friendly features. However, the extremely strong N≡N triple-bonds in nitrogen molecules and the competitive hydrogen evolution reaction lead to the unsatis-factory NH3 yield and the Faradaic efficiency (FE) of eNRR, making the development of high-performance catalysts with adequate active sites and high selectivity essential for further development of eNRR. Addressing this, we herein report a Bi and K dual-doped titanium oxide (BTO@KTO) material, which is prepared by a cation exchange reaction between K2Ti4O9 and molten BiCl3, for high-performance eNRR catalysts. Benefiting from the controllable molten-salt cation exchange process, a highly active surface containing Bi/K sites and rich oxygen vacancies has been obtained on titanium oxide. Under the synergy of these two merits, an efficient eNRR catalysis, with the NH3 yield rate of 32.02 Lg h-1 mg-1 and the FE of 12.71%, has been achieved, much superior to that of pristine K2Ti4O9. This work thus offers a high-performance electrocatalyst for eNRR, and more importantly, a versatile cation-exchange strategy for effi-ciently manipulating materials' functionalities.

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Self-supporting and dual-active 3D Co-S nanosheets constructed by ligand replacement reaction from MOF for rechargeable Al battery Aijing Lv, Songle Lu, Mingyong Wang, Haotian Shi, Wenjing Yan, Shuqiang Jiao 2022, 69(6): 35-43.  DOI: 10.1016/j.jechem.2021.12.022 Abstract ( 4 )   PDF (4599KB) ( 1 )   Metal sulfides with high theoretical capacities are expected as promising cathode materials of Al batteries (AIBs). However, powdery active materials are mainly synthesized and loaded on current collector by insulating binder without capacity. Meanwhile, S as inert element in metal sulfides can not usually pro-vide capacity. So, powdery metal sulfides only exhibit limiting practical capacity and poor cycling stabil-ity due to weak conductivity and low mass utilization. Herein, the novel self-supporting and dual-active Co-S nanosheets on carbon cloth (i.e. Co-S/CC) with hierarchically porous structure are constructed as cathode of AIBs. Co-S nanosheets are derived from ZIF-67 nanosheets on CC by a facile ligand replacement reaction. As a result, the binder-free Co-S/CC cathode with good conductivity delivers excellent initial dis-charge capacity of 383.4 mAh g-1 (0.211 mAh cm-2) at current density of 200 mA g-1 and maintain rever-sible capacity of 156.9 mAh g-1 (0.086 mAh cm-2) with Coulombic efficiency of 95.8% after 500 cycles, which are much higher than those of the traditional slurry-coating cathodes. Both Co and S as active ele-ments in Co-S/CC contribute to capacity, which leads to a high mass utilization. This work provides a sig-nificant strategy for the construction of self-supporting metallic cathode for advanced high-energy density Al battery.

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Pt-Co single atom alloy catalysts: Accelerated water dissociation and hydrogen evolution by strain regulation Rendian Wan, Mi Luo, Jingbo Wen, Shilong Liu, Xiongwu Kang, Yong Tian 2022, 69(6): 44-53.  DOI: 10.1016/j.jechem.2021.12.045 Abstract ( 11 )   PDF (5187KB) ( 7 )   The alkaline hydrogen evolution reaction (HER) on Pt-based catalysts is largely limited by the slow water dissociation kinetics. Pt-based single atom alloy catalysts (SAAC) with water dissociation sites have been demonstrated as excellent alkaline HER catalysts. However, the regulation of their activity and stability at the atomic scale is still a great challenge. Herein, the kinetic and stability issues are successfully resolved via engineering the electronic structure of Pt-Co SAAC by Au-induced tensile strain. The atomic dispersion of Co into the Pt shell was confirmed by extended X-ray absorption fine structure and the electronic structure and catalytic HER performance was modulated by the tensile strain induced by the Pt shell thickness. An inverse volcano-type relation between HER activity and surface strain was found. Density functional theory (DFT) calculations reveal that the Au-induced tensile strain on Pt-Co shell can not only boost the adsorption and dissociation kinetics of water at Co site by upshifting the d-band and promoting the electron transfer, but also downshift the d-band center of Pt in Pt-Co shell, lead-ing to optimized H* adsorption/desorption. The champion catalyst provides an overpotential of only 14 mV at the current density of 10 mA cm-2. This work not only provides an effective strategy for the construction of single-atom alloy electrocatalysts for high performance toward alkaline HER but also sheds light on the understanding of the reaction mechanism at the atomic level.

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Non-precious metal electrocatalysts for two-electron oxygen electrochemistry: Mechanisms, progress, and outlooks Yuhan Wu, Jianhui Sun, Shixue Dou, Jingyu Sun 2022, 69(6): 54-69.  DOI: 10.1016/j.jechem.2021.12.028 Abstract ( 5 )   PDF (9493KB) ( 3 )   Hydrogen peroxide (H2O2) is a valuable chemical for a wide variety of applications. The environmentally friendly production route of the electrochemical reduction of O2 to H2O2 has become an attractive alter-native to the traditional anthraquinone process. The efficiency of electrosynthesis process depends con-siderably on the availability of cost-effective catalysts with high selectivity, activity, and stability. Currently, there are many outstanding issues in the preparation of highly selective catalysts, the explo-ration of the interface electrolysis environment, and the construction of electrolysis devices, which have led to extensive research efforts. Distinct from the existing few comprehensive review articles on H2O2 production by two-electron oxygen reduction, the present review first explains the principle of the oxy-gen reduction reaction and then highlights recent advances in the regulation and control strategies of dif-ferent types of catalysts. Key factors of electrode structure and device design are discussed. In addition, we highlight the promising co-production combination of this system with renewable energy or energy storage systems. This review can help introduce the potential of oxygen reduction electrochemical pro-duction of high-flux H2O2 to the commercial market.

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Plating current density distribution of lithium metal anodes in pouch cells Shi-Jie Yang, Xin Shen, Xin-Bing Cheng, Feng-Ni Jiang, Rui Zhang, He Liu, Lei Liu, Hong Yuan 2022, 69(6): 70-75.  DOI: 10.1016/j.jechem.2021.12.049 Abstract ( 8 )   PDF (2845KB) ( 4 )   The uniformity of current density distribution upon electrodes is one of the most important factors deter-mining the lithium dendrites growth and cycling performance of lithium metal batteries (LMBs). Herein, current density distributions of lithium metal anodes induced by various engineering factors, consisting of uneven cathode, electrolyte distribution, and different tab positions, and their effects on the electro-chemical performance are investigated theoretically and experimentally in pouch cells. The deviation of current density in lithium metal anodes ranges from 2.47% to 196.18% due to the different levels of uneven cathode materials. However, the deviation is just 13.60% for different electrolyte thicknesses between cathodes and anodes, even a ten-layer separator in some positions. The maximum deviation for variational tab positions is only 0.17%. The nonuniformity in current density distribution results in severe dendrite growth issues and poor electrochemical performance of LMBs. This work not only con-firms the direct correlation between the uneven current density distribution and lithium deposition behaviors, but also points out the decisive effects of cathode surface roughness on current distribution of anodes, to which more attentions should be paid in practical applications of LMBs.

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Uniform zinc deposition on O,N-dual functionalized carbon cloth current collector Mengqi Zhou, Guoqiang Sun, Shuang-Quan Zang 2022, 69(6): 76-83.  DOI: 10.1016/j.jechem.2021.12.040 Abstract ( 5 )   PDF (7059KB) ( 2 )   The society's urgent demand for environmentally friendly, safe and low-cost energy storage devices has promoted the research of aqueous zinc-ion batteries. However, the uneven deposition of Zn ions on anodes will lead to the growth of the dendrite and reduce the Coulombic efficiency as well as the lifespan of the devices. Herein, we construct an O,N-dual functionalized carbon cloth current collector via a simple hydrothermal strategy, in which the oxygen-containing functional groups and the N heteroatoms can regulate the transmission and deposition of Zn ions, respectively. The proposed synergistic strategy ensures the uniform distribution of Zn ions on the surface of the Zn anode and inhibits the formation of dendrites. The symmetric cell based on the O,N-dual doped carbon cloth presents superior cycling sta-bility (318 h) with a low voltage hysteresis (11.2 mV) at an areal capacity of 1 mAh cm-2 (20% depth of diacharge). Meanwhile, the appreciably low overpotential (16 mV) and high Columbic efficiency (98.2%) also demonstrate that the O,N-dual functionalized carbon cloth can be worked as a promising host for Zn ions deposition.

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Recent advances in ‘‘water in salt” electrolytes for aqueous rechargeable monovalent-ion (Li+, Na+, K+) batteries Hong Gao, Kaikai Tang, Jun Xiao, Xin Guo, Weihua Chen, Hao Liu, Guoxiu Wang 2022, 69(6): 84-99.  DOI: 10.1016/j.jechem.2021.12.025 Abstract ( 1 )   PDF (8439KB) ( 3 )   Aqueous rechargeable batteries have attracted enormous attention owning to their intrinsic characteris-tics of non-flammability, low cost, and the superior ionic conductivity of the aqueous electrolyte. However, the narrow electrochemical stability window (1.23 V), imposed by hydrogen and oxygen evo-lution, constrains the overall energy density of batteries. The revolutionary ‘‘water-in-salt” electrolytes considerably expand the electrochemical stability window to 3 or even 4 volts, giving rise to a new series of high-voltage aqueous metal-ion chemistries. Herein, the recent advances in ‘‘water-in-salt” elec-trolytes for aqueous monovalent-ion (Li+, Na+, K+) rechargeable batteries have been systematically reviewed. Meanwhile, the corresponding reaction mechanisms, electrochemical performances and the existing challenges and opportunities are also highlighted.

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Building ultra-stable K-Te battery by molecular regulation Jiawan Zhou, Dongyang Shen, Xinzhi Yu, Bingan Lu 2022, 69(6): 100-107.  DOI: 10.1016/j.jechem.2021.10.001 Abstract ( 3 )   PDF (5645KB) ( 2 )   Tellurium (Te) is an ideal electrode for potassium ion batteries (PIBs) owing to its excellent electronic conductivity and high volumetric capacity. However, the Te electrode is prone to capacity fading as the shuttle effect. To address this challenge, we propose molecular regulated Se-Te solid solutions on N-doped porous carbon as the PIBs electrode. After optimizing the Se content in Se-Te solid solutions, the resultant SeTe6.8 on N-doped porous carbon (SeTe6.8@C) delivered a capacity of over 400 mAh g-1 with a flat plateau of 1.0 V at 500 mA g-1. It also achieved a superiorly long cycle life, running for more than 1600 cycles (over 7 months with 0.015% degeneration per cycle) at 100 mA g-1 and excellent rate performance (179.9 mAh g-1 at 10000 mA g-1). This remarkable electrochemical energy storage of the Te electorde likely arises from suppression of the shuttle effect after doping the Te with strongly electroneg-ative Se atoms (forming K5Te3 which is not easily soluble in electrolyte). This study presents a fresh approach for designing and developing ultra-stable Te-based electrodes for PIBs and beyond.

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Facile solution-processed molybdenum oxide as hole transporting material for efficient organic solar cell Qian Kang, Chenyi Yang, Bowei Xu, Jianhui Hou 2022, 69(6): 108-114.  DOI: 10.1016/j.jechem.2021.12.037 Abstract ( 4 )   PDF (8458KB) ( 3 )   The large energy barrier in hole extraction still remains a great challenge in developing hole transporting layer (HTL) materials for organic solar cells (OSCs). Thus, solution-processed HTL materials with excellent hole collection ability and good compatibility with large-area processing technique are strongly desired for OSCs. Herein, we developed a cost-effective and solution-processed MoO3 HTL for efficient OSCs. By adding a small amount of glucose as reducing reagent into the ammonium molybdate precursor solution, a deeply n-doped MoO3, namely G:Mo, was prepared through the sol-gel method. Compared to pristine MoO3, the conductivity of G:Mo was enhanced by two orders of magnitude, which greatly improved the hole collection ability of the HTL. OSCs with G:Mo can exhibit comparable PCE to the PEDOT:PSS device. Using PBDB-TF:BTP-eC9 as the active layer, a PCE of 17.1% is obtained for the device, which is the highest PCE value for OSC using a solution-processed MoO3 HTL. More importantly, G:Mo is well compatible with the blade-coating processing. The OSC using a blade-coated G:Mo showed almost no PCE loss as com-pared to the device with spin-coated G:Mo HTL. The results from this work indicate that G:Mo is a promising HTL material for the practical production of OSCs.

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Piezoelectric nanofoams with the interlaced ultrathin graphene confining Zn-N-C dipoles for efficient piezocatalytic H2 evolution under low-frequency vibration Penghui Hu, Yan Xu, Yanhua Lei, Jie Yuan, Rui Lei, Rong Hu, Junkang Chen, Difa Xu, Shiying Zhang, Ping Liu, Xiangchao Zhang, Xiaoqing Qiu, Wenhui Feng 2022, 69(6): 115-122.  DOI: 10.1016/j.jechem.2022.01.009 Abstract ( 8 )   PDF (8918KB) ( 4 )   Unique nanofoams consisting of interweaved ultrathin graphene confining Zn-N-C dipoles (ZnNG) are constructed via calcination of Zn-coordinated precursor. Due to the introduction of local polar Zn-N-C configurations, with hypersensitivity for mechanical stress, the piezoelectricity is created on the non-piezoelectric graphene, and the hierarchical ZnNG exhibits obvious piezocatalytic activity of water split-ting for H2 production even under mild agitation. The corresponding rate of H2 production is about 14.65 Lmol g-1 h-1. It triggers a breakthrough in piezocatalytic H2 evolution under low-frequency vibra-tion, and takes a significant step forward for piezocatalysis towards practical applications. Furthermore, the presented concept of confining atomic polar configuration for engineering piezoelectricity would open up new horizon for constructing new-type piezoelectrics based on both piezoelectric and nonpiezo-electric materials.

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Phenylfluorenamine-functionalized poly(N-vinylcarbazole)s as dopant-free polymer hole-transporting materials for inverted quasi-2D perovskite solar cells Zhengwu Pan, Han Gao, Yingying Yang, Qin Zou, Darui Peng, Pinghui Yang, Jiangli Cai, Jin Qian, Jiewei Li, Chengrong Yin, Nana Wang, Renzhi Li, Jianpu Wang, Wei Huang 2022, 69(6): 123-131.  DOI: 10.1016/j.jechem.2022.01.013 Abstract ( 6 )   PDF (4606KB) ( 2 )   In order to improve the efficiency and stability of inverted three-dimensional (3D) or quasi-2D perovskite solar cells (PSCs) for future commercialization, exploring high efficient dopant-free polymer hole-transporting materials (HTMs) is still desired and meaningful. One simple and efficient way to achieve high performance dopant-free HTMs is to synthesize novel non-conjugated side-chain polymers via rational molecular design. In this work, N-(4-methoxyphenyl)-9,9-dimethyl-9H-fluoren-2-amine (FMeNPh) groups are introduced into the poly(N-vinylcarbazole) (PVK) side chains to afford two non-conjugated polymers PVCz-DFMeNPh and PVCz-FMeNPh as dopant-free HTMs in inverted quasi-2D PSCs. Benefited from the flexible properties of polyethylene backbone and excellent optoelectronic nat-ures of FMeNPh side-chain groups, PVCz-DFMeNPh with more FMeNPh units exhibited excellent thermal stability, well-matched energy levels and improved charge mobility as compared to PTAA and PVCz-FMeNPh. Moreover, the morphologies investigation of quasi-2D perovskite on PVCz-DFMeNPh shows more compact and homogeneous perovskite films than those on PTAA and PVCz-FMeNPh. As a result, the dopant-free PVCz-DFMeNPh based inverted quasi-2D PSCs deliver power conversion efficiency (PCE) up to 18.44% as well as negligible hysteresis and favorable long-term stability, which represents as excellent performance reported to date for inverted quasi-2D PSCs. The results demonstrate the great potentials of constructing non-conjugated side-chain polymer HTMs based on phenylfluorenamine-func tionalized PVK for the development of high efficient and stable inverted 3D or quasi-2D PSCs.

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The roles of MXenes in developing advanced lithium metal anodes Nicolas Lucero, Dayannara Vilcarino, Dibakar Datta, Meng-Qiang Zhao 2022, 69(6): 132-149.  DOI: 10.1016/j.jechem.2022.01.011 Abstract ( 6 )   PDF (8726KB) ( 2 )   Lithium (Li) metal has emerged as the most promising anode for rechargeable Li batteries owing to its high theoretical specific capacities, low negative electrochemical potential, and superior electrical con-ductivity. Replacing the conventional graphite anodes with Li metal anodes (LMAs) provides great poten-tial to exceed the theoretical limitations of current commercial Li-ion batteries, leading to next-generation high-energy-density rechargeable Li metal batteries (LMBs). However, further development of LMAs is hindered by several inherent issues, such as dangerous dendrite growth, infinite volume change, low Coulombic efficiency, and interfacial side reactions. MXenes, a family of two-dimensional (2D) transition metal carbides and/or nitrides, have recently attracted much attention to address these issues due to their 2D structure, lithiophilic surface terminations, excellent electrical and ionic conduc-tivity, and superior mechanical properties. Herein, an overview of recent advances in the roles of MXenes for stabilizing LMAs is presented. In particular, strategies of utilizing MXenes as the Li hosts, arti-ficial protection layers, electrolyte additives, and for separator modifications to develop stable and dendrite-free LMAs are discussed. Moreover, a perspective on the current challenges and potential out-looks on MXenes for advanced LMAs is provided.

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Crystal structure and optical performance analysis of a new type of persistent luminescence material with multi-functional application prospects Songsong Ding, Pohua Chen, Haijie Guo, Peng Feng, Yunpeng Zhou, Yuhua Wang, Junliang Sun 2022, 69(6): 150-160.  DOI: 10.1016/j.jechem.2021.12.047 Abstract ( 5 )   PDF (7803KB) ( 2 )   Persistent luminescence (PersL) materials, as environmentally friendly and energy-saving materials, have broad application prospects in many fields such as lighting, chemistry and even biomedicine. However, studies on the types, performances and mechanism of PersL materials are still insufficient, which signif-icantly restricts their development and application. Under this consideration, we successfully synthesized a yellow PersL material CaSrGa4O8 (CSG). The crystal structure was studied in detail through Rotation Electron Diffraction (RED) and Powder X-ray Diffraction (PXRD). What's more, by co-doping Mn2+ and Yb3+, the afterglow brightness of CSG could be increased by nearly 20 times, and the afterglow duration could reach more than 6 h. It is worth mentioning that the samples also have excellent performances in mechanical luminescence (ML), photostimulated luminescence (PSL) and cathodoluminescence (CL), which was also investigated systematically. Finally, an anti-counterfeiting label was designed by the samples to reveal the potential of their application in anti-counterfeiting. The results showed that our research not only provided a new candidate PersL material for multifunctional applications, but also gave good help for studying the physical and chemical properties of CSG.

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Ge nanoparticles uniformly immobilized on 3D interconnected porous graphene frameworks as anodes for high-performance lithium-ion batteries Yao Chen, Yuming Zou, Xiaoping Shen, Jingxia Qiu, Jiabiao Lian, Jinrui Pu, Sheng Li, Fei-Hu Du, Shang-Qi Li, Zhenyuan Ji, Aihua Yuan 2022, 69(6): 161-173.  DOI: 10.1016/j.jechem.2021.12.051 Abstract ( 5 )   PDF (12565KB) ( 2 )   Germanium (Ge), an alloy-type anode material for lithium-ion batteries (LIBs), possesses many advan-tages such as high theoretical capacity and decent electrical conductivity. Nevertheless, its application is restricted by tremendous volume variation and tardy reaction kinetic during discharge/charge process. In this paper, the Ge/3DPG composites with Ge nanoparticles uniformly dispersed in 3D interconnected porous graphene (3DPG) skeleton are successfully prepared using a template-assisted in-situ reduction method. The unique 3D interconnected porous graphene can not only enhance the electronic conductiv-ity and reaction kinetics of the materials, but also provide sufficient buffer space to effectively mitigate the volume expansion during cycling and strengthen the structural integrity. Moreover, the small-sized Ge nanoparticles in close conjunction with the 3D graphene can boost the surface-controlled reaction of the electrode, which contributes to a fast charge-discharge rate capability. The Ge/3DPG composite with optimized Ge/graphene mass ratio delivers high reversible specific capacity (1102 mAh g-1 after 100 cycles at 0.2 C), outstanding rate capability (494 mAh g-1 at 5 C), and admirable cycling stability (85.3% of capacity retention after 250 cycles at 0.5 C). This work provides a significant inspiration for the design and fabrication of advanced Ge-based anode materials for next-generation high-performance LIBs.

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Effect of structural variation in biomass-derived nonfluorinated ionic liquids electrolytes on the performance of supercapacitors Inayat Ali Khan, Yong-Lei Wang, Faiz Ullah Shah 2022, 69(6): 174-184.  DOI: 10.1016/j.jechem.2021.12.041 Abstract ( 9 )   PDF (7546KB) ( 2 )   There is a growing interest in sustainable and high performance supercapacitors (SCs) operating at ele-vated temperatures as they are highly demanded in heat-durable electronics. Here, we present a biomass-derived nonfluorinated ionic liquid (IL) [P4444][HFuA] and its structural analogue [P4444][TpA] as electrolytes for supercapacitors comprising multiwall carbon nanotubes and activated charcoal (MWCNTs/AC) mixed carbon composite electrodes. A detailed investigation of the effect of scan rate, tem-perature, potential window and orientation of ions on the electrodes surfaces is performed. The superca-pacitors exhibited relatively lower specific capacitance for both [P4444][HFuA] and [P4444][TpA] ILs at room temperature. However, the specific capacitance has significantly increased with an increase in tem-perature and potential window. The equivalent serie resistances of the SCs is deceased with increasing temperatures, which is a result of improved ionic conductivities of the IL electrolytes. In CV cycling at 60 °C, the capacitor with [P4444][HFuA] IL-based electrolyte retained about 90% of its initial capacitance, while the capacitor with [P4444][TpA] IL-based electrolyte retained about 83% of its initial capacitance. Atomistic computations revealed that the aromatic [FuA]- and [TpA]- anions displayed perpendicular distribution that can effectively neutralize charges on the carbon surfaces. However, the [HFuA]- anion exhibited somewhat tilted configurations on the carbon electrode surfaces, contributing to their out-standing capacitive performance in electrochemical devices.

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Re nanoclusters anchored on nanosheet supports: Formation of Re-O-matrix bonding and evaluation as all-pH-range hydrogen evolution reaction (HER) electrocatalysts Shiyu Xu, Hao Li, Jeongbok Lee, N. Clament Sagaya Selvam, Baotao Kang, Jin Yong Lee, Pil J. Yoo 2022, 69(6): 185-193.  DOI: 10.1016/j.jechem.2021.12.050 Abstract ( 4 )   PDF (5380KB) ( 3 )   Although the water splitting-based generation of hydrogen as an energy carrier can help to mitigate the global problems of energy shortage and climate change, the practical implementation of this strategy is hindered by the absence of inexpensive high-performance electrocatalysts for the hydrogen evolution reaction (HER). Re-based HER electrocatalysts exhibit predictable high performance within the entire pH range but suffer from arduous formation (i.e., vulnerability to oxidation) and uncontrollable aggrega-tion, which strongly discourages the maximisation of active site exposure required for activity enhance-ment. To overcome these limitations, we herein hydrothermally synthesise Re nanoclusters uniformly distributed on nanosheet supports, such as reduced graphene oxide nanosheets (Re NCs@rGO), revealing that this hybrid features abundant exposed active sites and high oxidation resistance. The obtained elec-trocatalysts were elaborately characterized by microscopic and spectroscopic analyses. Also, density functional theory calculations confirm the optimised synthesis of Re NCs@rGO and indicate the crucial role of Re-O-C junction formation in securing durability. The effective suppression of Re nanocluster detachment/dissolution under HER conditions endows Re NCs@rGO with high electron conductivity and electrochemical stability, resulting in a durability superior to that of commercial Pt/C and an activity similar to that of this reference. As a result, Re NCs@rGO exhibited remarkably small HER overpotentials of 110, 130, and 93 mV to deliver a current density of 10 mA cm-2 in 0.5 M H2SO4, 1 M PBS, and 1 M KOH, respectively. Thus, Re NCs@rGO is a promising alternative to conventional Pt-group-metal catalysts and should find applications in next-generation high-performance water splitting systems.

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Dielectric polymer based electrolytes for high-performance all-solid-state lithium metal batteries Qi Kang, Yong Li, Zechao Zhuang, Dingsheng Wang, Chunyi Zhi, Pingkai Jiang, Xingyi Huang 2022, 69(6): 194-204.  DOI: 10.1016/j.jechem.2022.01.008 Abstract ( 37 )   PDF (6242KB) ( 21 )   Solid polymer electrolytes (SPEs) are urgently required for achieving practical all-solid-state lithium metal batteries (ASSLMBs) but remain plagued by low ionic conductivity. Herein, we propose a strategy of salt polarization to fabricate a highly ion-conductive SPE by employing a high-dielectric polymer that can interact strongly with lithium salts. Such a polymer with large dipole moments can guide lithium cations (Li+) to be arranged along the chain, forming a continuous pathway for Li+ hopping within the SPE. The as-fabricated SPE, poly(vinylidene difluoride) (PVDF)-LiN(SO2F)2 (LiFSI), has an extraordinarily high dielectric constant (up to 108) and ultrahigh ionic conductivity (0.77 × 10-3 S cm-1). Based on the PVDF-LiFSI SPE, the assembled Li metal symmetrical cell shows excellent Li plating/stripping reversibility at 0.1 mA cm-2, 0.1 mAh cm-2 over 1500 h; the ASS LiFePO4 batteries deliver long-term cycling stability at 1 C over 350 cycles (2.74 mg cm-2) and an ultralong cycling lifespan of over 2600 h (100 cycles) with high loading (11.5 mg cm-2) at 28 °C. First-principles calculations further reveal the ion-dipole interactions-controlled conduction of Li+ in PVDF-LiFSI SPE along the PVDF chain. This work highlights the critical role of dielectric permittivity in SPE, and provides a promising path towards high-energy, long-cycling lifespan ASSLMBs.

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Dual-layer vermiculite nanosheet based hybrid film to suppress dendrite growth in lithium metal batteries Xiang-Qun Xu, Feng-Ni Jiang, Shi-Jie Yang, Ye Xiao, He Liu, Fangyang Liu, Lei Liu, Xin-Bing Cheng 2022, 69(6): 205-210.  DOI: 10.1016/j.jechem.2022.01.019 Abstract ( 6 )   PDF (1544KB) ( 2 )   Lithium metal anode has become a favorable candidate for next-generation rechargeable batteries. However, the unstable interface between lithium metal and electrolyte leads to the growth of dendrites, resulting in the low Coulombic efficiency and even the safety concerns. Herein, a rigid-flexible dual-layer vermiculite nanosheet (VN) based organic-inorganic hybrid film on lithium metal anode is proposed to suppress dendrite growth and relieve volume fluctuations. The inner mechanically robust VN layer (3 lm thick) enhances the mechanical properties of the protective layer, while the outer polymer (4 lm thick) can enhance the flexibility of the hybrid layer. The Li | Li symmetric cell with protected lithium shows an extended life of over 670 h. The full cell with Li anode protected by dual-layer interface exhibits a better capacity retention of 80% after 174 cycles in comparison to bare Li anode with 94 cycles. This study provides a novel approach and a significant step towards prolonging lifespan of lithium metal batteries.

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Self-assembled interlayer aiming at the stability of NiOx based perovskite solar cells Tonghui Guo, Zhi Fang, Zequn Zhang, Zhiqiang Deng, Rui Zhao, Jing Zhang, Minghui Shang, Xiaohui Liu, Ziyang Hu, Yuejin Zhu, Liyuan Han 2022, 69(6): 211-220.  DOI: 10.1016/j.jechem.2022.01.049 Abstract ( 3 )   PDF (7181KB) ( 2 )   Inorganic NiOx based inverted structure perovskite solar cells (PSCs) is reported to be more stable than that with the organic hole transport materials. In this work, NiOx/MAPbI3 interface chemical reaction induced instability of perovskite is unveiled: Ni3+ and I- exhibit redox reactions and deprotonation of MA+ happens, which result in interface defects and perovskite lattice deformation. Thus the defective interface accelerates the degradation of perovskite by defect pathways from the bottom interface to the perovskite surface contacting H2O/O2. Self-assembled interlayer of NH-2 end silane on NiOx separates the reactive NiOx and MAPbI3, tunes the interface energy states by -NH2 end group. As a result, the PSC based on the silane treated NiOx achieves enhanced PCE of 20.1% with decent stability under environmen-tal and extreme conditions (high temperature, high humidity, light infiltration). Our work highlights the interface chemical problem induced PSC instability and a simple interface modification to achieve the stable PSCs.

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Self-assembled, highly-lithiophilic and well-aligned biomass engineered MXene paper enables dendrite-free lithium metal anode in carbonate-based electrolyte Liwen Tan, Chuanliang Wei, Yuchan Zhang, Shenglin Xiong, Hui Li, Jinkui Feng 2022, 69(6): 221-230.  DOI: 10.1016/j.jechem.2022.01.024 Abstract ( 4 )   PDF (14238KB) ( 4 )   Lithium metal anode is the ideal candidate for high-energy-density rechargeable batteries. However, uncontrolled dendrite growth hampers its commercialization. Herein, a dendrite-free composite Li metal anode is realized by a flexible, freestanding, well-aligned and highly-lithiophilic MXene paper designed by a facile electrostatic self-assembly of the exfoliated MXene nanosheets and natural polysaccharide-chitosan (MX@CS). The MX@CS paper gets a well-aligned layered-3D structure with a micro-crumpled surface that can effectively decrease the local current density, guide even Li plating and suppress den-dritic Li growth. More importantly, surface-adsorbed chitosan endows enhanced lithiophilicity for MXene substrate and thus reduces the Li nucleation overpotential, which is confirmed by the density functional theory calculations. Abundant lithiophilic groups on MX@CS surface provide high-concentration Li+ anchoring site promoting Li nucleation and laterally inducing uniform Li deposition, which effectively avoids the formation of dendritic Li. As a result, the MX@CS-Li anode with a dendrite-free Li morphology shows a significantly improved cycling life in commercial carbonate-based electrolyte. When coupled with LiNi0.8Co0.1Mn0.1O2 cathode, the full cell exhibits a low capacity decay and steady ultrahigh Coulombic efficiency of 99.6% at a current density of 5C. These findings develop a new approach for designing high-performance metal-based rechargeable batteries.

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Sustainable synthesis of high-density fuel via catalytic cascade cycloaddition reaction Xiaolin Luo, Rui Lu, Xiaoqin Si, Huifang Jiang, Quan Shi, Haixia Ma, Cong Zhang, Jie Xu, Fang Lu 2022, 69(6): 231-236.  DOI: 10.1016/j.jechem.2022.01.029 Abstract ( 6 )   PDF (2638KB) ( 3 )   The access to high-density hydrocarbon fuels from biomass for the reduction of dependence on fossil resources has been a research highlight in recent years. It is well known that cycloalkanes are the com-ponents of fuels with higher energy density than straight or branched alkanes. Herein, we developed a new catalytic pattern to synthesize dimethyltetradecahydroanthracenes (DMTHA), a kind of tricyclic alkane, from biomass-derived isoprene and p-benzoquinone via a cascade Diels-Alder reaction followed by a hydrodeoxygenation reaction. Vanadium supported on titanium dioxide (V-TiO2) was applied to cat-alyze the cascade Diels-Alder reaction and it was disclosed that V with appropriate V4+/V5+ ratio on the surface of TiO2 could activate quinones. Experimental tests showed that the heating value of final prod-ucts was up to 45.7 MJ/kg. The development of new high-density fuel molecules is a long-term trend for the future renewable and sustainable fuel energy application.

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Host-guest supramolecular interaction behavior at the interface between anode and electrolyte for long life Zn anode Kai Wu, Fanghua Ning, Jin Yi, Xiaoyu Liu, Jiaqian Qin, Yuyu Liu, Jiujun Zhang 2022, 69(6): 237-243.  DOI: 10.1016/j.jechem.2022.01.037 Abstract ( 3 )   PDF (2671KB) ( 3 )   The hydrogen evolution reaction (HER) and dendrite growth associated with Zn anode have become the main bottlenecks for the further development of zinc ion batteries (ZIBs). In this work, the electrochem-ical activity of H3O+ is inhibited by the supramolecular host-guest complex composed of H3O+ as guest and 18-crown-6 as host. The even Zn plating is induced by the host-guest complex electrostatic shielding layer on Zn anode, as detected by in-situ optical microscopy. The lamellar Zn is plated which profits from the improved Zn plating behavior. Density functional theory (DFT) calculation presents the stable struc-ture of complex. The less produced H2 content is monitored online by a mass spectrometer during Zn plating/stripping, which indicates HER can be hampered by the host-guest behavior. Thus, the ZIBs with long life and high Coulombic efficiency are achieved via introducing 18-crown-6. The proposed host-guest supramolecular interaction is expected to facilitate the furthermore development of Zn batteries.

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Electrochemical lithium ions pump for lithium recovery from brine by using a surface stability Al2O3-ZrO2 coated LiMn2O4 electrode Guiling Luo, Lin Zhu, Xiaowei Li, Guolang Zhou, Jing Sun, Linlin Chen, Yanhong Chao, Lei Jiang, Wenshuai Zhu 2022, 69(6): 244-252.  DOI: 10.1016/j.jechem.2022.01.012 Abstract ( 5 )   PDF (3910KB) ( 4 )   The rapid commercialization of lithium-ion batteries has caused significant expansion of the lithium demand. Electrochemical lithium ions pump is a promising technology because of its good selectivity and friendly environment. Herein, an Al2O3-ZrO2 film coating of the LiMn2O4 (AlZr-LMO) electrode is prepared and operated for recovery of Li+ from brine. The Li+ maximum extraction capacity of AlZr-LMO reached 49.92 mg/g in one cycle. Compared with the solely LMO electrode, the AlZr-LMO demon-strated evident electrochemical stability and cycle life towards the Li+ recovery system. After 30 succes-sive cycles, the extraction capacity for Li+ increased from 29.21% to 57.67%. The high cycle capacity of the material could be attributed to its low polarization, high active sites, and good chemical stability of the electrode surface owing to the synergy function of Al2O3-ZrO2 in the charging-discharging process. A dynamic model parameter identification method was performed to evaluate the active site of AlZr-LMO. This work may provide a way to design the AlZr-LMO electrode and develop a good method for the recovery of lithium from brine.

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Unveiling the effect of amino acids on the crystallization pathways of methylammonium lead iodide perovskites Wenhao Zhang, Jiankang Du, Weihua Zhang, Yanmeng Chu, Anyi Mei, Yaoguang Rong, Xinyu Gao, Hongwei Han, Yue Hu 2022, 69(6): 253-260.  DOI: 10.1016/j.jechem.2021.12.048 Abstract ( 4 )   PDF (3398KB) ( 2 )   Multifunctional additives are widely used to improve crystallization and to passivate defects in per-ovskite solar cells. The roles of these additives are usually related to the various functional groups con-tained in such additives. Here, we introduce a serious of analogues of amino acids into methylammonium lead iodide perovskites and find they play different roles in the crystallization process despite the fact that these additives share exactly the same terminal groups, namely one amino group and one carboxyl group. The corresponding crystallization pathways are established for the first time via monitoring the time-resolved phase formation and transformation. We find that avoiding the rapid formation of per-ovskites from precursor solution can facilitate the uniform nucleation and growth of perovskite crystals with enhanced crystallinity and reduced defects. Further, we find the different crystallization behaviors probably arise from the inherent structural characteristic of these additives, leading to different interac-tions in the precursors. This study unveils the effects of amino acids on the liquid-solid crystallization process and helps better understand the role of multifunctional additives beyond their functional groups.

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Enhanced proton irradiation resistance in Cs-doped CH3NH3PbI3 films and solar cells Pan Luo, Xue-Yin Sun, Hao Jiang, Li Yang, Yang Li, Wen-Zhu Shao, Liang Zhen, Cheng-Yan Xu 2022, 69(6): 261-269.  DOI: 10.1016/j.jechem.2022.01.014 Abstract ( 6 )   PDF (3844KB) ( 2 )   Mixed-cation perovskite solar cells have attracted tremendous attention in space applications due to their excellent power conversion efficiency (PCE) and stability to light and heat. Although the evolution of photovoltaic performance in different space environments has been investigated, the role of inorganic cesium ions (Cs+) in the enhancement of irradiation resistance needs to be further clarified. Herein, the structure and performance evolution of Cs-doped CH3NH3PbI3 (MAPbI3) films and planar heterojunction devices under proton irradiation up to 1 × 1016 p cm-2 were studied. 5% of Cs+ doping can increase the cohesive energy of MAPbI3 and effectively alleviate the lattice strain induced by proton irradiation, thereby enhancing the crystallinity and stability of films. The bandgap changes of irradiated Cs0.05MA0.95PbI3 films under the identical fluence were only one third of that of MAPbI3 films. Upon irra-diation under the fluence of 1 × 1014 p cm-2, the density of trap states in the undoped and 5%Cs-doped films increased by 71% and 9%, respectively, and the average PCE of 20 corresponding devices decreased only by 12% and 9%, respectively. This proves that the replacement of organic methylamine ion with inor-ganic cesium ion contributes to the improvement of MAPbI3 resistance to proton irradiation, thus con-firming the application prospects of mixed-cation or all-inorganic perovskite solar cells in spacecraft.

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MnO2 nanosheet modified N, P co-doping carbon nanofibers on carbon cloth as lithiophilic host to construct high-performance anodes for Li metal batteries Xiaoqiang Liu, Qian Zhang, Yiru Ma, Zhenzhen Chi, Huixiang Yin, Jie Liu, Junfei Huang, Ziyang Guo, Lei Wang 2022, 69(6): 270-281.  DOI: 10.1016/j.jechem.2021.12.046 Abstract ( 6 )   PDF (10014KB) ( 3 )   Lithium (Li) metal batteries have attracted much attention owing to its ultra-high energy density. However, as important part of Li metal batteries, Li anodes still face many challenges, mainly including uncontrolled dendritic Li formation, dramatical volume variation and serious pulverization. Herein, man-ganese dioxide (MnO2) nanosheet modified nitrogen (N), phosphorus (P) co-doping carbon nanofibers (NPC) on carbon cloth (CC) (MnO2@NPC-CC) is successfully fabricated through electrodeposition approach and further treated with Li by the molten-infusion method to prepare Li based Mn@NPC-CC (Li-Mn@NPC-CC) electrode. The synergy of MnO2 and NPC obviously increases the reaction rate between MnO2@NPC-CC and Li and guides even Li distribution over infusion process. Additionally, theoretical cal-culation, simulation and experimental results further indicate that N, P, Mn multi-doping effectively improves the superior lithiophilicity of Li-Mn@NPC-CC, which induces uniform Li deposition/dissolution to suppress dendrite growth over cycles. Moreover, conductive and porous NPC matrix not only effec-tively improves the stability of Li-Mn@NPC-CC, but also provides abundant spaces to accelerate the trans-fer of ion/electron and buffer electrode dimension variation during cycling. Hence, Li-Mn@NPC-CC-based symmetric cells exhibit extra-long cycling life (over 2200 h) with small hysteresis of 20 mV. When the Li-Mn@NPC-CC anode couples with air, Li iron phosphate (LiFePO4), or hard carbon (C) cathode, the assem-bled full cells exhibit outstanding performance with low hysteresis and stable cycling properties. Especially, the corresponding pouch-typed Li-air cells also exhibit good performance at different bending angles and even power a series of electronic devices.

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Upcycling biomass waste into Fe single atom catalysts for pollutant control Xin Li, Kang Hu, Yizhe Huang, Qingqing Gu, Yuwen Chen, Bing Yang, Rongliang Qiu, Wenhao Luo, Bert M. Weckhuysen, Kai Yan 2022, 69(6): 282-291.  DOI: 10.1016/j.jechem.2022.01.044 Abstract ( 8 )   PDF (7478KB) ( 8 )   Contaminants of heavy metals and antibiotics, which are frequently detected in water, soil and food chains with increasing prevalence in our current society, can cause potential harm to human health and disrupt human ecosystem irreversibly. Herein, we have successfully utilized biomass waste ferns contaminated by iron mines, to fabricate a first-of-its-kind high-performance class of Fe single-atom cat-alysts (FeSAC) by a facile pyrolysis. The optimal FeSAC-800 shows an excellent efficiency in the fast-photocatalytic degradation of six types of quinolone antibiotics (e.g., norfloxacin, levofloxacin, ciproflox-acin, enrofloxacin, lomefloxacin, flumequine) in 1 h under the simulated natural light irradiation. Based on advanced characterization, a well-defined structure of FeN4, confined in the porous carbon is elabo-rated for the FeSAC-800. Mechanism of the photodegradation is via a Fenton-like oxidation process whereas the reactive oxygen species play a key role. These findings open a new avenue for efficient, sus-tainable utilization of biomass waste in pollutant control.

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Bifunctional ZnCo2S4@CoZn13 hybrid electrocatalysts for high efficient overall water splitting Depeng Zhao, Meizhen Dai, Hengqi Liu, Zhongxin Duan, Xiaojie Tan, Xiang Wu 2022, 69(6): 292-300.  DOI: 10.1016/j.jechem.2022.01.042 Abstract ( 6 )   PDF (14675KB) ( 1 )   To develop highly active and low-cost electrocatalyst is very important to improve the efficiency of water splitting. However, the current catalysts still present serious challenges due to the poor intrinsic activity and high overpotential. Herein, we report several amino induced Co-based composite catalysts. As a structure-mediating agent, ethylenediamine (EDA) can not only regulate the crystal structure and but also provide many surface amino groups. The obtained ZnCo2S4/CoZn13 catalysts show an excellent oxygen evolution reaction (OER) performance (274 mV@50 mA cm-2) and the overpotential of 160 mV at -10 mA cm-2 for hydrogen evolution reaction (HER). For electrolysis of water, the electrocatalysts deliver a cell voltage of 1.61 V at 50 mA cm-2. This study provides a facile synthetic strategy to construct advanced electrocatalysts for future applications.

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Stability and deactivation of OER electrocatalysts: A review Feng Zeng, Chalachew Mebrahtu, Longfei Liao, Anna Katharina Beine, Regina Palkovits 2022, 69(6): 301-329.  DOI: 10.1016/j.jechem.2022.01.025 Abstract ( 151 )   PDF (19337KB) ( 114 )   Recently, H2 has attracted increasing attention as green energy carrier holding the possibility to replace fossil fuel-based energy sources and thereby reduce CO2 emissions. Green hydrogen can be generated by water electrolysis using renewable energies like wind and solar power. When it is combusted, only water forms as by-product. However, the efficiency of water electrolysis is hampered by the anodic oxygen evo-lution reaction (OER) because of the slow kinetics which leads to a high overpotential. Therefore, many catalysts have been developed for OER to facilitate the kinetics and reduce the overpotential. In addition to electrocatalytic activity, the stability of the catalysts is imperative for industrial application and has been intensively studied. In this review, we cover recent findings on the stability and deactivation mech-anisms of OER catalysts. We discuss the correlation between OER activity and stability, methodologies and experimental techniques to study the stability and deactivation as well as the deactivation mecha-nisms, together with factors influencing stability. Furthermore, strategies for stabilizing and regenerating OER catalysts as well as methods to predict stability are summarized. Finally, the review highlights emerging methodologies yet to be explored and future directions of stability studies and the design of highly stable OER catalysts.

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Redirecting dynamic structural evolution of nickel-contained RuO2 catalyst during electrochemical oxygen evolution reaction Yuhan Zhao, Menghua Xi, Yanbin Qi, Xuedi Sheng, Pengfei Tian, Yihua Zhu, Xiaoling Yang, Chunzhong Li, Hongliang Jiang 2022, 69(6): 330-337.  DOI: 10.1016/j.jechem.2022.01.030 Abstract ( 9 )   PDF (3931KB) ( 3 )   Electrochemical oxygen evolution reaction (OER) is a main efficiency bottleneck of water electrolysis. Commercial ruthenium oxide (RuO2) catalyst displays remarkable activities but poor stability for OER. The instability stems from lattice oxygen oxidation, resulting in the oxidation of Ru4+ to soluble Rux+ (x > 4) species. Herein, we redirect dynamic structural evolution of Ru-based catalysts through introduc-ing oxidized nickel (Ni) components. By virtue of comprehensive structural characterizations, such as high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), X-ray photo-electron spectroscopy (XPS), operando Raman and so forth, it is demonstrated that when the atomic con-tent of Ni exceeds that of ruthenium (Ru), the Ni components can efficiently inhibit the Ru4+ oxidation and structural collapse. Density functional theory (DFT) calculations suggest that the introduction of Ni component hinders the formation of oxygen vacancies, and makes lattice oxygen mediated mecha-nism turn to adsorbate evolution mechanism, which eventually improves the stability. The optimized nickel-contained RuO2 catalyst delivers an effective reactivity with an overpotential of less than 215 mV to attain 10 mA cm-2 and remarkable stability with only 5 mV increment after 5000 potential cycles. This work provides insights into the origin of dynamic structural evolution of transition-metal-modified RuO2 electrocatalysts.

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High-energy sodium-ion hybrid capacitors through nanograin-boundary-induced pseudocapacitance of Co3O4 nanorods Wenliang Feng, Venkata Sai Avvaru, Steven J. Hinder, Vinodkumar Etacheri 2022, 69(6): 338-346.  DOI: 10.1016/j.jechem.2022.01.017 Abstract ( 11 )   PDF (4652KB) ( 6 )   Sodium-ion hybrid capacitors (SICs) have been proposed to bridge performance gaps between batteries and supercapacitors, and thus realize both high energy density and power density in a single configura-tion. Nevertheless, applications of SICs are severely restricted by their insufficient energy densities (<100 Wh/kg) resulted from the kinetics imbalance between cathodes and anodes. Herein, we report a nanograin-boundary-rich hierarchical Co3O4 nanorod anode composed of ~20 nm nanocrystallites. Extreme pseudocapacitance (up to 72%@1.0 mV/s) is achieved through nanograin-boundary-induced pseudocapacitive-type Na+ storage process. Co3O4 nanorod anode delivers in this case highly reversible capacity (810 mAh/g@0.025 A/g), excellent rate capability (335 mAh/g@5.0 A/g), and improved cycle sta-bility (100 cycles@1.0 A/g with negligible capacity degradation). The outstanding performance can be credited to the hierarchical morphology of Co3O4 nanorods and the well-designed nanograin-boundaries between nanocrystallites that avoid particle agglomeration, induce pseudocapacitive-type Na+ storage, and accommodate volume variation during sodiation-desodiation processes. Nitrogen-doping of the Co3O4 nanorods not only generates defects for extra surficial Na+ storage but also increases the electronic conductivity for efficient charge separation and lowers energy barrier for Na+ intercalation. Synergy of conventional reaction mechanism and pseudocapacitive-type Na+ storage enables high speci-fic capacity, rapid Na+ diffusion, and improved structural stability of the Co3O4 nanorod electrode. The SIC integrating this highly pseudocapacitive anode and activated carbon cathode delivers exceptional energy density (175 Wh/kg@40 W/kg), power density (6632 W/kg@37 Wh/kg), cycle life (6000 cycles@1.0 A/g with a capacity retention of 81%), and coulombic efficiency (~100%).

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Corrigendum to ‘‘Single-atom catalysts for CO oxidation, CO2 reduction, and O2 electrochemistry” [J. Energy Chem. 65 (2022) 254-279] Wenyu Yuan, Yiyuan Ma, Heng Wu, Laifei Cheng 2022, 69(6): 347-347.  DOI: 10.1016/j.jechem.2021.12.044 Abstract ( 2 )   PDF (350KB) ( 2 )

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Self-template-oriented synthesis of lead-free perovskite Cs3Bi2I9 nanosheets for boosting photocatalysis of CO2 reduction over Z-scheme heterojunction Cs3Bi2I9/CeO2 You-Xiang Feng, Guang-Xing Dong, Ke Su, Zhao-Lei Liu, Wen Zhang, Min Zhang, Tong-Bu Lu 2022, 69(6): 348-355.  DOI: 10.1016/j.jechem.2022.01.015 Abstract ( 14 )   PDF (10926KB) ( 4 )   Lead halide perovskite (LHP) nanocrystals have been intensely studied as photocatalysts for artificial pho-tosynthesis in recent years. However, the toxicity of lead in LHP seriously limits their potential for wide-spread applications. Herein, we first present the synthesis of 2D lead-free halide perovskite (Cs3Bi2I9) nanosheets with self-template-oriented method, in which BiOI/Bi2O2.7 nanosheets were used as the tem-plate and Bi ion source simultaneously. Through facile electrostatic self-assembly strategy, a Z-scheme heterojunction composed of Cs3Bi2I9 nanosheets and CeO2 nanosheets (Cs3Bi2I9/CeO2-3:1) was con-structed as photocatalyst for the photo-reduction of CO2 coupled with the oxidation of H2O. Due to the matching energy levels and the close interfacial contact between Cs3Bi2I9 and CeO2 nanosheets, the sep-aration efficiency of the photogenerated carriers in Cs3Bi2I9/CeO2-3:1 composite was significantly improved. Consequently, the environment-friendly halide perovskite heterojunction Cs3Bi2I9/CeO2-3:1 presents impressive photocatalytic activity for the reduction of CO2 to CH4 and CO with an electron con-sumption yield of 877.04 lmol g—1, which is over 7 and 15 times higher than those of pristine Cs3Bi2I9 and CeO2 nanosheets, exceeding the yield of other reported bismuth-based perovskite for photocatalytic CO2 reduction.

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Electrochemically induced phase transition in a nanoflower vanadium tetrasulfide cathode for high-performance zinc-ion batteries Shizhe Gao, Peng Ju, Ziquan Liu, Lei Zhai, Wenbao Liu, Xiaoyu Zhang, Yanli Zhou, Caifu Dong, Fuyi Jiang, Jianchao Sun 2022, 69(6): 356-362.  DOI: 10.1016/j.jechem.2022.01.003 Abstract ( 8 )   PDF (3360KB) ( 3 )   Aqueous zinc-ion batteries (AZIBs) are promising contenders for large-scale energy storage with the mer-its of their low cost, high safety, environmental friendliness, and competitive gravimetric energy density. Nevertheless, suitable cathode materials with long cycle life and adequate capacity are still rare. Herein, we report a nanoflower vanadium tetrasulfide/carbon nanotubes (VS4/CNTs) cathode with high Zn-storage performance. We propose a phase transition reaction mechanism from VS4 to zinc pyrovanadate in the initial cycles and a reversible intercalation mechanism for Zn2+ in zinc pyrovanadate during sub-sequent cycles. As a result, the cathode delivers a high discharge capacity of 265 mAh g-1 at 0.25 A g-1 and 182 mAh g-1 at 7 A g-1. In addition, the cathode exhibits a long-term cyclability with 93% capacity retention over 1200 cycles at 5 A g-1. VS4/CNTs with superior electrochemical performance is a hopeful cathode material in AZIBs.

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Precisely quantifying bulk transition metal valence evolution in conventional battery electrode by inverse partial fluorescence yield Kehua Dai, Weiwei Shao, Beibei Zhao, Wenjuan Zhang, Yan Feng, Wenfeng Mao, Guo Ai, Gao Liu, Jing Mao, Wanli Yang 2022, 69(6): 363-368.  DOI: 10.1016/j.jechem.2022.01.004 Abstract ( 5 )   PDF (2084KB) ( 2 )   Precisely quantifying transition metal (TM) redox in bulk is a key to understand the fundamental of opti-mizing cathode materials in secondary batteries. At present, the commonly used methods to probe TM redox are hard X-ray absorption spectroscopy (hXAS) and soft X-ray absorption spectroscopy (sXAS). However, they are both facing challenges to precisely quantify the valence states of some transition met-als such as Mn. In this paper, Mn-L iPFY (inverse partial fluorescence yield) spectra extracted from Mn-L mRIXS (mapping of resonant inelastic X-ray scattering) is adopted to quantify Mn valence states. Mn-L iPFY spectra has been considered as a bulk-sensitive, non-distorted probe of TM valence states. However, the exact precision of this method is still unclear in quantifying practical battery electrodes. Herein, a series of LiMn2O4 electrodes with different charge and discharge states are prepared. Based on their electrochemical capacity (generally considered to be very precise), the precision of Mn iPFY in quantifying bulk Mn valence state is confirmed, and the error range is unraveled. Mn-L mRIXS iPFY thus is identified as one of the best methods to quantify the bulk Mn valence state comparing with hXAS and sXAS.

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From trash to treasure: Chemical recycling and upcycling of commodity plastic waste to fuels, high-valued chemicals and advanced materials Fan Zhang, Fang Wang, Xiangyue Wei, Yang Yang, Shimei Xu, Dehui Deng, Yu-Zhong Wang 2022, 69(6): 369-388.  DOI: 10.1016/j.jechem.2021.12.052 Abstract ( 90 )   PDF (9645KB) ( 66 )   Of all the existing materials, plastics are no doubt among the most versatile ones. However, the extreme increases in plastic production as well as the difficulty of the material for degradation have led to a huge number of plastic wastes. Their recycling rate after disposal is less than 10%, resulting in a series of seri-ous environmental and ecological problems as well as a significant waste of resources. Current recycling methods generally suffer from large energy consumption, the low utilization rate of recycled products with low added value, and produce other waste during the process. Here, we summarized recently-developed chemical recycling ways on commodity plastics, especially new catalytic paths in production of fuels, high-valued chemicals and advanced materials from a single virgin or a mixture of plastic waste, which have emerged as promising ways to valorize waste plastics more economically and environmen-tally friendly. The new catalyst design criteria as well as innovative catalytic paths and technologies for plastic upcycling are highlighted. Beyond energy recovery by incineration, these approaches demonstrate how waste plastics can be a viable feedstock for energy use with the generation of clean H2, high-quality liquid fuels and materials for energy storage, and help inspiring more catalytic process on plastic upcy-cling to overcome the economical hurdle and building a circular plastic economy.

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Revealing the critical effect of solid electrolyte interphase on the deposition and detriment of Co(Ⅱ) ions to graphite anode Qiming Xie, Jiawei Chen, Lidan Xing, Xianggui Zhou, Zekai Ma, Binhong Wu, Yilong Lin, Hebing Zhou, Weishan Li 2022, 69(6): 389-396.  DOI: 10.1016/j.jechem.2021.12.009 Abstract ( 11 )   PDF (5078KB) ( 9 )   ‘‘Dissolution, migration, and deposition” of transition metal ions (TMIs) result in capacity degradation of lithium-ion batteries (LIBs). Understanding such detrimental mechanism of TMIs is critical to the devel-opment of LIBs with long cycle life. In most previous works, TMIs were directly introduced into the elec-trolyte to investigate such a detrimental mechanism. In these cases, the TMIs are deposited directly on the fresh anode surface. However, in the practical battery system, the TMIs are deposited on the anode covered with solid electrolyte interphase (SEI) film. Whether the pre-presence of SEI film on anode sur-face influences the deposition and detriment of TMIs is unclear. In this work, the deposition of Co element on graphite anode with and without SEI film were systematically studied. The results clearly show that, in comparison with that of fresh graphite (SEI-free), the presence of SEI film aggravates the deposition of Co ions due to the Li+-Co2+ ion exchange between the SEI and Co2+-containing electrolyte without the driv-ing of the electric field, leading to faster capacity fading of graphite anode. Therefore, how to regulate electrolytes and film-forming additives to design the components of SEI and prevent its exchange with TMIs, is a crucial way to inhibit the deposition and detriment of TMIs on graphite anode.

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Regulating local chemistry in ZrCo-based orthorhombic hydrides via increasing atomic interference for ultra-stable hydrogen isotopes storage Zhaoqing Liang, Zhendong Yao, Ruhong Li, Xuezhang Xiao, Zhichao Ye, Xuancheng Wang, Jiacheng Qi, Jiapeng Bi, Xiulin Fan, Huaqin Kou, Wenhua Luo, Changan Chen, Lixin Chen 2022, 69(6): 397-405.  DOI: 10.1016/j.jechem.2022.01.006 Abstract ( 5 )   PDF (5085KB) ( 2 )   Developing a universal and reliable strategy for the modulation of composition and structure of energy storage materials with stable cycling performance is vital for hydrogen and its isotopes storage advanced system, yet still challenging. Herein, an ultra-stable lattice structure is designed and verified to increase atomic chaos and interference for effectively inhibiting disproportionation reaction and improving cycling stability in ZrCo-based hydrogen isotopes storage alloy. After screening in terms of configuration entropy calculation, we construct Zr1—xNbxCo1—2xCuxNix (x = 0.15, 0.2, 0.25) alloys with increased atomic chaos, and successfully achieve stable isostructural de-/hydrogenation during 100 cycles, whose cycling capacity retentions are above 99%, much higher than 22.4% of pristine ZrCo alloy. Both theoretical anal-ysis and experimental evidences indicate the high thermo-stability of orthorhombic lattice in Zr0.8Nb0.2Co0.6Cu0.2Ni0.2 alloy. Notably, the increased atomic chaos and interference in Zr0.8Nb0.2Co0.6Cu0.2Ni0.2 alloy causes regulation in hydrogen local chemical neighborhood, thereby con-fusing the hydrogen release order, which effectively eliminates lattice distortion and unlocks an ultra-stable lattice structure. This study provides a new and comprehensive inspiration for hydrogen atoms transport behaviors and intrinsic reason of stable orthorhombic transformation, which can contribute to paving the way for other energy storage materials modulation.

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Tartaric acid additive to enhance perovskite multiple preferential orientations for high-performance solar cells Zhen Wang, Shuai You, Guanhaojie Zheng, Zengguang Tang, Liujiang Zhang, Junhan Zhang, Xiong Li, Xingyu Gao 2022, 69(6): 406-413.  DOI: 10.1016/j.jechem.2022.02.007 Abstract ( 5 )   PDF (3397KB) ( 6 )   Perovskite film quality is a decisive factor governing the performance and long-term stability of per-ovskite solar cells (PSCs). To passivate defects for high-quality perovskite films, various additives have been explored in perovskite precursor with notable achievements in the development of high-performance PSCs. Herein, tartaric acid (TA) was applied as additive in perovskite precursor solution to modulate the crystal growth leading to high quality thin films with enhanced multiple preferential ori-entations favoring efficient charge transport along multiple directions. It is also noticed that TA can improve the energy level alignment in PSCs, which effectively accelerates both carrier extraction and transportation with non-radiative recombination suppressed at the perovskite interfaces. Based on the present perovskite films, the fabricated PSCs achieved an excellent champion power conversion efficiency (PCE) of 21.82% from that of 19.70% for the control device without TA additive. In addition, a PSC with TA additive was shown to exhibit impressive operational stability by retaining 92% of its initial PCE after ~1200 h of aging at room temperature in ambient air with a relative humidity of about 10%-25%. In sum-mary, the present work demonstrates a facile and versatile approach by using TA as additive in perovskite precursor to fabricate high quality perovskite films with enhanced multiple preferential orientations for high-efficiency stable PSCs.

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FeFx and Fe2ZrO5 Co-modified hematite for highly efficient solar water splitting Xiaoquan Zhao, Cheng Lu, Shuo Li, Yufeng Chen, Gaoteng Zhang, Duo Zhang, Kun Feng, Jun Zhong 2022, 69(6): 414-420.  DOI: 10.1016/j.jechem.2022.01.045 Abstract ( 4 )   PDF (3233KB) ( 2 )   Hematite is an excellent catalyst for photoelectrochemical (PEC) water splitting but its performance has been highly limited by poor conductivity and high charge recombination. Here by a Zr-based treatment to create bulk Fe2ZrO5 in hematite and a F-based treatment to form an ultrathin surface FeFx layer, the charge transfer can be highly improved and the charge recombination can be significantly suppressed. As a result, the FeFx/Zr-Fe2O3 photoanode presents an enhanced PEC performance with a photocurrent density of 2.43 mA/cm2 at 1.23 V vs. RHE, which is around 3 times higher than that of the pristine Fe2O3. The FeFx/Zr-Fe2O3 photoanode also shows a low onset potential of 0.77 V vs. RHE (100 mV lower than the pristine hematite). The performance is much higher than that of the sample treated by Zr or F alone, suggesting the synergistic effect between bulk Fe2ZrO5 and surface FeFx. By coupling with the FeNiOOH co-catalyst, the final photoanode can achieve a high photocurrent density of 2.81 mA/cm2 at 1.23 V vs. RHE. The novel design of Zr and F co-modified hematite can be used as a promising way to pre-pare efficient catalysts for solar water splitting.

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A flexible artificial solid-electrolyte interlayer supported by compactness-tailored carbon nanotube network for dendrite-free lithium metal anode Haowen Liu, Jifang Zhang, Yang Liu, Yang Wei, Shuaiyang Ren, Ludi Pan, Yi Su, Jianhua Xiao, Haiyan Fan, Yitao Lin, Yipeng Su, Yuegang Zhang 2022, 69(6): 421-427.  DOI: 10.1016/j.jechem.2022.01.033 Abstract ( 7 )   PDF (12469KB) ( 1 )   A dendrite-free lithium metal anode requires a stable interface designed for efficient and reversible lithium plating and stripping. In this work, we have devised a mechanically flexible artificial Li3N solid-electrolyte interlayer supported by a dual-layer compactness-tailored carbon nanotube fiber net-work. The more compact side of the network ensures a full coverage of Li3N, which prevents the reaction between electrolyte and lithium. The other side, with sparsely distributed nanotube fibers, provides mechanical flexibility for the film, and induces three-dimensional lithium deposition along its structure without any dendrite formation. The resulting full cell with NCM811 cathode has a high capacity reten-tion of 95.1% for 160 cycles compared with less than 80% for the control.

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Regulating the radical intermediates by conjugated units in covalent organic frameworks for optimized lithium ion storage Shuai Gu, Xiaoxia Ma, Jingjing Chen, Rui Hao, Zhiqiang Wang, Ning Qin, Wei Zheng, Qingmeng Gan, Wen Luo, Muqing Li, Zhiqiang Li, Kemeng Liao, Hao Guo, Guiyu Liu, Kaili Zhang, Zhouguang Lu 2022, 69(6): 428-433.  DOI: 10.1016/j.jechem.2022.01.005 Abstract ( 5 )   PDF (5010KB) ( 2 )   Organic active units often transform into radical intermediates during the redox processes but exhibit poor cycling stability due to the uncontrollable redox of the radicals. Herein, we report a facile and effi-cient strategy to modulate the molecular orbital energies, charge transport capacities, and spin electron densities of the active units in covalent organic frameworks (COFs) via regulating the conjugated unit size to optimize the redox activity and stability of the organic radicals. COFs based on different imide conju-gated units exhibit tunable discharge voltages, rate performance and cycling stabilities. Detailed charac-terizations and theoretical calculation reveal that imide radicals are the important active intermediates during the redox processes of these COFs. Specifically, increasing the size of the imide conjugated units could effectively delocalize the radical electrons and improve the stability of the COFs electrodes. This study offers a very effective strategy to modulate the redox chemistry of organic materials for electro-chemical energy storage.

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Boosting the oxygen evolution reaction through migrating active sites from the bulk to surface of perovskite oxides Zhengsen Wang, Ziyi Hao, Fang Shi, Kaiyue Zhu, Xuefeng Zhu, Weishen Yang 2022, 69(6): 434-441.  DOI: 10.1016/j.jechem.2022.01.039 Abstract ( 3 )   PDF (4363KB) ( 2 )   The oxygen evolution reaction (OER) dominates the efficiency of electrocatalytic water splitting owing to its sluggish kinetics. Perovskite oxides (ABO3) have emerged as promising candidates to accelerate the OER process owing to their high intrinsic activities and tailorable properties. Fe ions in perovskite oxides have been proved to be a highly catalytic element for OER, while some Fe-based perovskites such as SrTi0.8Fe0.2O3-d (STF) and La0.66Ti0.8Fe0.2O3-d (LTF) exhibit inferior OER activity. Yet the essential reason is still unclear and the effective method to promote the activity of such perovskite is also lacking. Herein, an in-situ exsolution strategy was proposed to boost the OER by migrating Fe from the bulk to the surface. Significantly enhanced OER activity was achieved on STF and LTF perovskites with surface-decorated oxygen vacancies and Fe nanoparticles. In addition, theoretical calculation confirmed that the oxygen vacancies and Fe nanoparticle on surface could lower the overpotential of OER by facilitating the adsorption of OH-. From this study, migration of the active elements in perovskite is found to be an effective strategy to increase the quantity and activity of active sites, providing new insights and under-standing for designing efficient OER catalysts.

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A comprehensive modification enables the high rate capability of P2-Na0.75Mn0.67Ni0.33O2 for sodium-ion cathode materials Xiaochen Feng, Yong Li, Qinhao Shi, Xuan Wang, Xiuping Yin, JingWang, Zhonghong Xia, Haiyan Xiao, Aibing Chen, Xinxin Yang, Yufeng Zhao 2022, 69(6): 442-449.  DOI: 10.1016/j.jechem.2022.01.032 Abstract ( 7 )   PDF (10251KB) ( 4 )   The Na+/vacancy ordering can effectively affect the electrochemical behavior of P2-type cathode material. In this work we proposed an integrated strategy by attaining a high Na content, In3+ doping in conjunc-tion with NaInO2 coating in the P2-Na0.75Mn0.67Ni0.33O2 which can inhibit the sodium vacancy order, smooth the electrochemical curve, and enhance the structural stability and rate capability. A combination of X-ray diffraction analysis and DFT calculation indicate that the In3+ ions in the Na layer serve as ‘‘pil-lars” to stabilize the layered structure, especially for high current density charging. The P2-Na0.75Mn0.67Ni0.33In0.02O2 with an impressive sodium content exhibits a remarkable reversible capacity of 109.6 mAh g-1, superior rate capability capacity of 79.8 mAh g-1 at 20 C, and 85% capacity retention after 100 cycles at 5 C. This work demonstrates an efficient approach for the comprehensive optimization of sodium ion cathode materials.

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Confining ultrahigh oxygen vacancy SnO2 nanocrystals into nitrogen-doped carbon for enhanced Li-ion storage kinetics and reversibility Ying Liu, Chen Hu, Ling Chen, Yanjie Hu, Hao Jiang, Chunzhong Li 2022, 69(6): 450-455.  DOI: 10.1016/j.jechem.2022.01.021 Abstract ( 3 )   PDF (4256KB) ( 2 )   Oxygen vacancies (VO) engineering has been deemed to an effective tactic for enhancing Li-ion storage kinetics and reversibility of SnO2-based anode materials. Herein, we demonstrated the confinement of ultrahigh VO SnO2 nanocrystals into N-doped carbon frameworks to boost their high-rate and cycle life. Density functional theory (DFT) calculations reveal that abundant VO in SnO2 facilitates the adsorption to Li-ion with remarkably increased carrier concentration. The 6.0 nm-sized SnO2 particles and the embed-ded design effectively stabilize the structural integrity during de-/lithiation. Meantime, the as-formed large hetero-interface also expedites the electron transfer. These merits guarantee its high-rate perfor-mance and superior cycling stability. Consequently, this sample exhibits a high capacity of 1368.9 mAh g-1 at 0.1 A g-1, and can still maintain 488.5 mAh g-1 at 10 A g-1 and a long life over 400 cycles at 5 A g-1 with 96.6% capacity retention, which is among the best report for Sn-contained anode mate-rials. This work sheds light on ultrahigh Vo and structural design in conversion-type oxides for high-performance lithium-ion batteries (LIBs).

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Tuning precise numbers of supported nickel clusters on graphdiyne for efficient CO2 electroreduction toward various multi-carbon products Meiqi Yang, Zhongxu Wang, Dongxu Jiao, Yu Tian, Yongchen Shang, Lichang Yin, Qinghai Cai, Jingxiang Zhao 2022, 69(6): 456-465.  DOI: 10.1016/j.jechem.2022.01.023 Abstract ( 9 )   PDF (10919KB) ( 5 )   Compared to single-atom catalysts, supported metal clusters can exhibit enhanced activity and desig-nated selectivity in heterogeneous catalysis due to their unique geometric and electronic features. Herein, by means of comprehensive density functional theory (DFT) computations, we systematically investigated the potential of several Ni clusters supported on graphdiyne (Nix/GDY, x = 1-6) for CO2 reduction reaction (CO2RR). Our results revealed that, due to the strong interaction between Ni atoms and sp-hybridized C atoms, these supported Ni clusters on GDY exhibit high stabilities and excellent elec-tronic properties. In particular, according to the computed free energy profiles for CO2RR on these Nix/ GDY systems, the anchored Ni4 cluster was revealed to exhibit high CO2RR catalytic activity with a small limiting potential and moderate kinetic barrier for C-C coupling, and CH4, C2H5OH, and C3H7OH were identified as the main products, which can be attributed to its strong capacity for CO2 activation due to its unique configuration and excellent electronic properties. Thus, by carefully controlling the precise numbers of atoms in sub-nano clusters, the spatially confined Ni clusters can perform as promising CO2RR catalysts with high-efficiency and high-selectivity, which may provide a useful guidance to further develop novel and low-cost metal clusters-based catalysts for sustain CO2 conversion to valuable chem-icals and fuels.

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Recent insights on iron based nanostructured electrocatalyst and current status of proton exchange membrane fuel cell for sustainable transport Mohamedazeem M. Mohideen, Adiyodi Veettil Radhamani, Seeram Ramakrishna, Yen Wei, Yong Liu 2022, 69(6): 466-489.  DOI: 10.1016/j.jechem.2022.01.035 Abstract ( 13 )   PDF (19926KB) ( 3 )   Bridging the performance gap of the electrocatalyst between the rotating disk electrode (RDE) and mem-brane electrode assembly (MEA) level testing is the key to reducing the total cost of proton exchange membrane fuel cell (PEMFC) vehicles. Presently, platinum metal accounts for ~42% of the total cost of the PEMFC vehicles for usage in the cathode catalyst layer, where the sluggish oxygen reduction reaction (ORR) occurs. An alternative to the platinum catalyst, the Fe-N-C catalyst has attracted considerable interest for PEMFC due to its cost-effectiveness and high catalytic activity towards ORR. However, the excellent ORR activity of Fe-N-C obtained from RDE studies rarely translates the same performance into MEA operating conditions. Such a performance gap is mainly attributed to the lack of atomic-level under-standing of Fe-N-C active sites and their ORR mechanism. Besides, unless the cost of expensive electro-catalyst is reduced, the total operation cost of the PEMFC vehicles remains constant. Therefore, developing highly efficient Fe-N-C catalysts from academic and industrial perspectives is critical for com-mercializing PEMFC vehicles. Here, the scope of the review is three-fold. First, we discussed the atomic-level insights of Fe-N-C active sites and ORR mechanism, followed by unraveling the different iron-based nanostructured ORR electrocatalysts, including oxide, carbide, nitride, phosphide, sulfide, and single-atom catalysts. And then we bridged their ORR catalytic performance gap between the RDE and MEA tests for real operating conditions of PEMFC vehicles. Second, we focused on bridging the cost barriers of PEMFC vehicles between capital, operation, and end-user. Finally, we provided the path to achieve sus-tainable development goals by commercializing PEMFC vehicles for a better world.

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Engineering Pt heterogeneous catalysts for accelerated liquid-solid redox conversion in Li-S batteries Qinhua Gu, Yujie Qi, Wuxing Hua, Tongxin Shang, Junnan Chen, Luozhen Jiang, Lina Li, Ming Lu, Yixiao Zhang, Xi Liu, Ying Wan, Bingsen Zhang 2022, 69(6): 490-496.  DOI: 10.1016/j.jechem.2022.01.016 Abstract ( 4 )   PDF (10189KB) ( 1 )   The shuttle effect caused by soluble lithium polysulfides (LiPSs) deteriorates multiphase transformation reaction kinetics of sulfur species, and gives rise to an unserviceable lithium-sulfur (Li-S) battery. Catalysis, as a process optimization approach, offers an option to eliminate the intrinsic issues. However, exploring and understanding the role of catalysts on electrode reaction remains critical bottle-necks, particularly as they are prone to continuous evolution under complex dynamic environment. Herein, platinum nanoparticles loaded on MXene nanosheets, as sulfur host, and the action of catalysts on the reaction process are investigated via ex-situ monitors upon solid-liquid-solid chemical transfor-mation of sulfur species. These traces confirm that the high performance originates from electron transfer between catalysts and LiPSs, which lowers the nucleation barrier from liquid LiPSs to solid Li2S/Li2S2. Further, the accelerated liquid-solid conversion can alleviate the accumulation of LiPSs, and boost the reaction kinetics in Li-S batteries. The findings corroborate the electronic modulation between catalysts and LiPSs, which is a generalizable strategy to optimize energy conversion efficiency of Li-S batteries.

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A molecular cobaloxime cocatalyst and ultrathin FeOOH nanolayers co-modified BiVO4 photoanode for efficient photoelectrochemical water oxidation Hongyun Cao, Taotao Wang, Jiaxing Li, Jinbao Wu, Pingwu Du 2022, 69(6): 497-505.  DOI: 10.1016/j.jechem.2022.01.028 Abstract ( 5 )   PDF (5094KB) ( 2 )   BiVO4 has been attracting a lot of interest in photoelectrochemical (PEC) water oxidation due to its effi-cient solar absorption and appropriate band positions. So far, sluggish water oxidation kinetics and fast photogenerated charge recombination still hinder the PEC performance of BiVO4. In this study, a novel PEC photoanode was designed by depositing ultrathin FeOOH nanolayers on the surface of nanoporous BiVO4 electrode, followed by modification with a cobaloxime (Co(dmgH)2(4-COOH-py)Cl) molecular cocatalyst. Under irradiation of a 100 mW cm-2 (AM 1.5G) Xe lamp, the photocurrent density of the coba-loxime/FeOOH/BiVO4 composite photoanode reached 5.1 mA cm-2 at 1.23 V vs. RHE in 1.0 M potassium borate buffer solution (pH = 9.0). The onset potential of the optimal cobaloxime/FeOOH/BiVO4 photoan-ode exhibited a 460 mV cathodic shift relative to bare BiVO4. In addition, the surface charge injection effi-ciency of the composite photoanode reached ~80% at 1.23 V vs. RHE and the incident photon-to-current efficiency (IPCE) reached ~88% at 420 nm.

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Nitrogen vacancies enriched Ce-doped Ni3N hierarchical nanosheets triggering highly-efficient urea oxidation reaction in urea-assisted energy-saving electrolysis Meng Li, Xiaodong Wu, Kun Liu, Yifan Zhang, Xuechun Jiang, Dongmei Sun, Yawen Tang, Kai Huang, Gengtao Fu 2022, 69(6): 506-515.  DOI: 10.1016/j.jechem.2022.01.031 Abstract ( 24 )   PDF (11011KB) ( 18 )   Urea oxidation reaction (UOR), which has favorable thermodynamic energy barriers compared with oxy-gen evolution reaction (OER), can provide more cost-effective electrons for the renewable energy sys-tems, but is trapped by its sluggish UOR kinetics and intricate reaction intermediates formation/ desorption process. Herein, we report a novel and effective electrocatalyst consisting of carbon cloth sup-ported nitrogen vacancies-enriched Ce-doped Ni3N hierarchical nanosheets (Ce-Ni3N@CC) to optimize the flat-footed UOR kinetics, especially the stiff rate-determine CO2 desorption step of UOR. Upon the introduction of valance state variable Ce, the resultant nitrogen vacancies enriched Ce-Ni3N@CC exhibits an enhanced UOR performance where the operation voltage requires only 1.31 V to deliver the current density of 10 mA cm-2, which is superior to that of Ni3N@CC catalyst (1.36 V) and other counterparts. Density functional theory (DFT) results demonstrate that the incorporation of Ce in Ni3N lowers the for-mation energy of nitrogen vacancies, resulting in rich nitrogen vacancies in Ce-Ni3N@CC. Moreover, the nitrogen vacancies together with Ce doping optimize the local charge distribution around Ni sites, and balance the adsorption energy of CO2 in the rate-determining step (RDS), as well as affect the initial adsorption structure of urea, leading to the superior UOR catalytic performance of Ce-Ni3N@CC. When integrating the Ce-Ni3N catalyst in UOR//HER and UOR//CO2R flow electrolyzer, both of them perform well with low operation voltage and robust long-term stability, proofing that the thermodynamically favorable UOR can act as a suitable substitute anodic reaction compared with that of OER. Our findings here not only provide a novel UOR catalyst but also offer a promising design strategy for the future devel-opment of energy-related devices.

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Decomposition pathway and stabilization of ether-based electrolytes in the discharge process of Li-O2 battery Xiao Liu, Xiaosheng Song, Qi Zhang, Xuebing Zhu, Qing Han, Zewen Liu, Peng Zhang, Yong Zhao 2022, 69(6): 516-523.  DOI: 10.1016/j.jechem.2022.01.007 Abstract ( 7 )   PDF (7896KB) ( 2 )   Ether-based electrolytes with relatively high stability are widely used in Li-O2 batteries (LOBs) with high energy density. However, they are still prone to be attacked by reactive oxygen species. Understanding the degradation chemistry of ether-based solvent induced by reactive oxygen species is significant importance toward selection of stable electrolytes for LOBs. Herein, we demonstrate that a great amount of H2 gas evolves on the Li anode during the long-term discharge process of LOBs, which is due to the electrolyte decomposition at the oxygen cathode. By coupling with in-situ and ex-situ characterization techniques, it is demonstrated that O-2 . induces the H-abstraction of tetraethylene glycol dimethyl ether (TEGDME) to produce a large amount of H2O at cathode, and this H2O migrates to Li anode and produce H2 gas. Based on the established experiments and spectra, a possible decomposition pathway of TEGDME caused by O-2 . at the discharge process is proposed. And moreover, three types of strategies are discussed to inhibit the decomposition of ether-based electrolytes, which should be highly important for the fun-damental and technical advancement for LOBs.

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Bi nanoparticles in situ encapsulated by carbon film as high-performance anode materials for Li-ion batteries Jun Yang, Jiahui Xian, Qinglin Liu, Yamei Sun, Guangqin Li 2022, 69(6): 524-530.  DOI: 10.1016/j.jechem.2022.01.026 Abstract ( 9 )   PDF (3911KB) ( 4 )   Bismuth (Bi) has indeed inspired great interests in lithium-ion batteries (LIBs) due to the high capacity, but was still limited by the low electrical conductivity and large volume variation. Herein, a composite material based on Bi nanoparticles in situ encapsulated by carbon film (Bi@CF) is prepared successfully through a facile metal-organic framework (MOF)-engaged approach. As anode materials for LIBs, the Bi@CF composites achieved high reversible capacities of 705 and 538 mAh g-1 at 0.2 and 0.5 A g-1 after 200 cycles, and long cycling performance with a stable capacity of 306 mAh g-1 at 1.0 A g-1 even after 900 cycles. In situ X-ray diffraction (XRD) measurements clearly revealed the conversion between Bi and Li3Bi during the alloying/dealloying process, confirming the good electrochemical reversibility of Bi@CF for Li-storage. The reaction kinetics of this Bi@CF composite was further studied by galvanostatic intermittent titration technique (GITT). This work may provide an inspiration for the elaborate design and facile preparation of alloy-type anode materials for high-performance rechargeable batteries.

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High-performance LiNi0.8Mn0.1Co0.1O2 cathode by nanoscale lithium sulfide coating via atomic layer deposition Xin Wang, Jiyu Cai, Yang Ren, Mourad Benamara, Xinwei Zhou, Yan Li, Zonghai Chen, Hua Zhou, Xianghui Xiao, Yuzi Liu, Xiangbo Meng 2022, 69(6): 531-540.  DOI: 10.1016/j.jechem.2022.02.015 Abstract ( 5 )   PDF (7701KB) ( 2 )   The commercialization of nickel-rich LiNi0.8Mn0.1Co0.1O2 (NMC811) has been hindered by its continuous loss of practical capacity and reduction in average working voltage. To address these issues, surface mod-ification has been well-recognized as an effective strategy. Different from the coatings reported in liter-ature to date, in this work, we for the first time report a sulfide coating, amorphous Li2S via atomic layer deposition (ALD). Our study revealed that the conformal nano-Li2S coating shows exceptional protection over the NMC811 cathodes, accounting for the dramatically boosted capacity retention from ~11.6% to ~71% and the evidently mitigated voltage reduction from 0.39 to 0.18 V after 500 charge-discharge cycles. In addition, the Li2S coating remarkably improved the rate capability of the NMC811 cathode. Our investigation further revealed that all these beneficial effects of the ALD-deposited nano-Li2S coating lie in the following aspects: (i) maintain the mechanical integrity of the NMC811 electrode; (ii) stabilize the NMC electrode/electrolyte interface; and (iii) suppress the irreversible phase transition of NMC struc-ture. Particularly, this study also has revealed that the nano-Li2S coating has played some unique role not associated with traditional non-sulfide coatings such as oxides. In this regard, we disclosed that the Li2S layer has reacted with the released O2 from the NMC lattices, and thereby has dramatically mitigated electrolyte oxidation and electrode corrosion. Thus, this study is significant and has demonstrated that sulfides may be an important class of coating materials to tackle the issues of NMCs and other layered cathodes in lithium batteries.

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Selective hydrogenation of 1,3-butadiene on iridium nanostructures: Structure sensitivity, host effect, and deactivation mechanism Mengru Wang, Yuxue Yue, Yi Wang, Xiaoling Mou, Renqin Chang, Zupeng Chen, Ronghe Lin, Jia Zhao, Yunjie Ding 2022, 69(6): 541-554.  DOI: 10.1016/j.jechem.2022.01.040 Abstract ( 5 )   PDF (16756KB) ( 2 )   A systematic study on the structure sensitivity, host effect, and the deactivation mechanism of Ir-catalyzed selective hydrogenation of 1,3-butadiene, a key process in the purification of alkadiene for the upgrading of C4 cut, is presented by coupling steady-state catalytic testing, in-depth characterization, kinetic evaluation, and density functional theory calculations. We reveal that: (i) 1,3-Butadiene hydro-genation on iridium is structure-sensitive with the optimal particle size of about 2 nm, and the H2 disso-ciation energy is a reliable activity descriptor; (ii) The nature of the NC hosts exerts a critical impact on the catalytic performance, and balanced nitrogen content and speciation seem key for the optimized per-formance; and (iii) Different deactivation mechanisms occur: fouling by coke deposition on the catalysts with a high N:C ratio (>1), and site blockage due to the competitive adsorption between 1-butene/cis-2-butene and 1,3-butadiene. These molecular insights provide valuable guidelines for the catalyst design in selective hydrogenations.

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Defect-rich potassium amide: A new solid-state potassium ion electrolyte Jiang Wang, Gangtie Lei, Teng He, Hujun Cao, Ping Chen 2022, 69(6): 555-560.  DOI: 10.1016/j.jechem.2022.01.046 Abstract ( 16 )   PDF (2390KB) ( 6 )   One of the major obstacles to the application of potassium-ion batteries in large-scale energy storage is the lack of safe and effective electrolytes. KNH2, a new potassium-ion solid electrolyte has been devel-oped in this study. Its ionic conductivity reaches 4.84 × 10-5 S cm-1 at 150 °C and can reach 3.56 × 10-4 S cm-1 after mechanochemical treatment. The result from electron paramagnetic resonance (EPR) measurement shows that the increment of ionic conductivity is dependent on the concentration of nitrogen defects in the KNH2 electrolyte. To the best of our knowledge, this is the first report that adopts inorganic amide as an electrolyte for potassium-ion battery and initiates the search for a new amide-based solid electrolyte for an all-solid-state potassium-ion battery.

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Origin of superior pseudocapacitive mechanism of transition metal nitrides Chao Huang, Ping Qin, Dan Li, Qingdong Ruan, Hao Song, Liangliang Liu, Yuzheng Wu, Yinghe Ma, Qingwei Li, Kaifu Huo, Paul K. Chu 2022, 69(6): 561-568.  DOI: 10.1016/j.jechem.2022.01.041 Abstract ( 6 )   PDF (7675KB) ( 2 )   Large-scale deployment of Internet of Things (IoT), a revolutionary innovation for a better world, is ham-pered by the limitation of energy self-sufficiency. Constructing transition metal nitride (TMN)-based micro-supercapacitors is a possible solution by taking advantage of the high conductivity, large specific capacitance, and large tap density of the materials. However, the pseudocapacitive storage mechanism of TMNs is still unclear consequently impeding the design of microdevices. Herein, the functions and mech-anism of TMNs with different metal oxynitride (TMNOx) concentrations in pseudocapacitive electrodes are investigated systematically by in situ Raman scattering, ex situ X-ray photoelectron spectroscopy, as well as ion isolation and substitution cyclic voltammetry. It is found that the specific capacitances of TMNs depend on the TMNOx concentrations and the N-M-O site is responsible for the large pseudo-capacitance via the Faradic reaction between TMNOx and OH-. Our study elucidates the mechanism per-taining to pseudocapacitive charge storage of TMNs and provides insights into the design and optimization of TMNOx as well as other electrode materials for pseudocapacitors.

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Water-induced electrode poisoning and the mitigation strategy for high temperature polymer electrolyte membrane fuel cells Zinan Zhang, Zhangxun Xia, Jicai Huang, Fenning Jing, Suli Wang, Gongquan Sun 2022, 69(6): 569-575.  DOI: 10.1016/j.jechem.2022.01.038 Abstract ( 6 )   PDF (3675KB) ( 3 )   Engineering failure of membrane electrode assembly caused by increasingly fuel poisoning in the high temperature polymer electrolyte membrane fuel cells fed with humidified reformate gases is firstly demonstrated herein this work. Based on the results of the in-situ environmental scanning electron microscope, electrochemical analyses, and limiting current method, a water-induced phosphoric acid invasion model is constructed in the porous electrode to elucidate the failure causations of the hindered hydrogen mass transport and the enhanced carbon monoxide poisoning. To optimize the phosphoric acid distribution under the inevitably humidified circumstance, a facile and effective strategy of constructing acid-proofed electrode is proposed and demonstrates outstanding stability with highly humidified refor-mate gases as anode fuel. This work discusses a potential defect that was rarely studied previously under practical working circumstance for high temperature polymer electrolyte membrane fuel cells, providing an alternative opinion of electrode design based on the fundamental aspects towards the engineering problems.

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Hydrogen production from methane and carbon dioxide mixture using all-solid-state electrochemical cell based on a proton-conducting membrane and redox-robust composite electrodes Denis Osinkin, Evgeniy Tropin 2022, 69(6): 576-584.  DOI: 10.1016/j.jechem.2022.02.019 Abstract ( 7 )   PDF (7426KB) ( 4 )   In recent years, interest in hydrogen as a fuel has sharply increased in the field of alternative and green energy due to its high energy capability and zero-emission behaviour. As a result, research in the devel-opment of new highly efficient methods for producing high-purity hydrogen is relevant. This paper pre-sents, for the first time, the test results of an electrochemical cell with a proton-conducting La0.9Sr0.1ScO3-δ electrolyte and symmetrical Sr1.95Fe1.4Ni0.1Mo0.5O6-δ+ La0.9Sr0.1Sc0.9Co0.1O3-δ electrodes as a hybrid setup utilizationsetup for electricity generation in proton ceramic fuel cell mode, for hydrogen separation from H2 + Ar mixture and the production of high-purity hydrogen from methane with simultaneous CO2 utilization. It was found that this electrochemical cell generates high flow rates of hydrogen during its separation through a proton-conducting membrane from H2 + Ar mixture, about 500 cm3 h-1 cm-2 at a current den-sity of 0.6 A cm-2 as well as about 370 cm3 h-1 cm-2 at a current density of 0.5 A cm-2 from CH4 + CO2 mixture at 800 °C which shows that these cells are promising for hydrogen production.

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Electrochemical deposited amorphous FeNi hydroxide electrode for oxygen evolution reaction Zhengzhi Yin, Runze He, Yongcai Zhang, Ligang Feng, Xiang Wu, Thomas Wågberg, Guangzhi Hu 2022, 69(6): 585-592.  DOI: 10.1016/j.jechem.2022.01.020 Abstract ( 9 )   PDF (3894KB) ( 9 )   The electrodeposition approach is significant in electrode fabrication for practical application. Herein, the electrodeposited amorphous NiFe hydroxide species for oxygen evolution reaction (OER) in water split-ting reaction is demonstrated by revealing the synergistic effect influenced by the support electrode of Fe and Ni foil and the contents of Fe and Ni in the electrolyte. All the electrodeposited samples have an amorphous structure and similar profiles of binding energy and chemical states for Fe and Ni as charac-terized by the spectroscopic techniques. While the support effect and Fe/Ni synergistic effect are indeed observed for the varied catalytic performances observed for the different electrodes; the Ni foil supported catalyst exhibits much higher performance than that of the Fe foil supported catalyst, and the different redox potentials of Ni species in the different Fe/Ni electrode resulting from the Fe-Ni synergism are observed in the cyclic voltammetry curve analysis. The surface roughness and the electrochemical surface area are also influenced by the support effect and the Fe/Ni ratio in the plating electrolyte. The optimal electrode shows a very low overpotential of ~200 mV to reach 10 mA cm-2, and very high catalytic sta-bility by the consecutive cyclic voltammetry measurements and 20 h stability test. Though it has the lar-gest electrochemical surface area, the highest catalytic efficiency for these active sites is also indicated by the specific activity and turnover frequency polarization curves. The current work shows the effective experience for the electrodeposited Fe/Ni based catalysts in large-scale fabrication, which can be more practical for hydrogen generation in the alkaline water electrolysis.

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In-depth investigation of the exothermic reactions between lithiated graphite and electrolyte in lithium-ion battery Yuejiu Zheng, Zhihe Shi, Dongsheng Ren, Jie Chen, Xiang Liu, Xuning Feng, Li Wang, Xuebing Han, Languang Lu, Xiangming He, Minggao Ouyang 2022, 69(6): 593-600.  DOI: 10.1016/j.jechem.2022.01.027 Abstract ( 28 )   PDF (2730KB) ( 21 )   Thermal runaway is a critical issue for the large application of lithium-ion batteries. Exothermic reactions between lithiated graphite and electrolyte play a crucial role in the thermal runaway of lithium-ion bat-teries. However, the role of each component in the electrolyte during the exothermic reactions with lithi-ated graphite has not been fully understood. In this paper, the exothermic reactions between lithiated graphite and electrolyte of lithium-ion battery are investigated through differential scanning calorimetry (DSC) and evolved gas analysis. The lithiated graphite in the presence of electrolyte exhibit three exother-mic peaks during DSC test. The reactions between lithiated graphite and LiPF6 and ethylene carbonate are found to be responsible for the first two exothermic peaks, while the third exothermic peak is attributed to the reaction between lithiated graphite and binder. In contrast, diethylene carbonate and ethyl methyl carbonate contribute little to the total heat generation of graphite-electrolyte reactions. The reaction mechanism between lithiated graphite and electrolyte, including the major reaction equations and gas products, are summarized. Finally, DSC tests on samples with various amounts of electrolyte are per-formed to clarify the quantitative relationship between lithiated graphite and electrolyte during the exothermic reactions. 2.5 mg of lithiated graphite (Li0.8627C6) can fully react with around 7.2 mg elec-trolyte, releasing a heat generation of 2491 J g-1. The results presented in this study can provide useful guidance for the safety improvement of lithium-ion batteries.

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Fast and extensive intercalation chemistry in Wadsley-Roth phase based high-capacity electrodes Miao Wang, Zhenpeng Yao, Qianqian Li, Yongfeng Hu, Xiuping Yin, Aibing Chen, Xionggang Lu, Jiujun Zhang, Yufeng Zhao 2022, 69(6): 601-611.  DOI: 10.1016/j.jechem.2022.02.014 Abstract ( 5 )   PDF (17205KB) ( 1 )   Wadsley-Roth (W-R) structured oxides featured with wide channels represent one of the most promising material families showing compelling rate performance for lithium-ion batteries. Herein, we report an in-depth study on the fast and extensive intercalation chemistry of phosphorus stabilized W-R phase PNb9O25 and its application in high energy and fast-charging devices. We explore the intercalation geom-etry of PNb9O25 and identify two geometrical types of stable insertion sites with the total amount much higher than conventional intercalation-type electrodes. We reveal the ion transportation kinetics that the Li ions initially diffuse along the open type III channels and then penetrate to edge sites with low kinetic barriers. During the lithiation, no remarkable phase transition is detected with nearly intact host phos-phorous niobium oxide backbone. Therefore, the oxide framework of PNb9O25 keeps almost unchanged with all the fast diffusion channels and insertion cavities well-maintained upon cycling, which accom-plishes the unconventional electrochemical performance of W-R structured electrodes.

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Influence of charge transport layer on the crystallinity and charge extraction of pure tin-based halide perovskite film Yaohong Zhang, Muhammad Akmal Kamarudin, Qiao Li, Chao Ding, Yong Zhou, Yingfang Yao, Zhigang Zou, Satoshi Iikubo, Takashi Minemoto, Kenji Yoshino, Shuzi Hayase, Qing Shen 2022, 69(6): 612-615.  DOI: 10.1016/j.jechem.2022.02.003 Abstract ( 8 )   PDF (1579KB) ( 5 )

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Enhanced ion conductivity and electrode-electrolyte interphase stability of porous Si anodes enabled by silicon nitride nanocoating for high-performance Li-ion batteries Shixiong Mei, Siguang Guo, Ben Xiang, Jiaguo Deng, Jijiang Fu, Xuming Zhang, Yang Zheng, Biao Gao, Paul K Chu, Kaifu Huo 2022, 69(6): 616-625.  DOI: 10.1016/j.jechem.2022.02.002 Abstract ( 13 )   PDF (6889KB) ( 7 )   Silicon (Si) is a promising anode material for next-generation high-energy lithium-ion batteries (LIBs) due to its high capacity. However, the large volumetric expansion, poor ion conductivity and unstable solid electrolyte interface (SEI) lead to rapid capacity fading and low rate performance. Herein, we report Si nitride (SiN) comprising stoichiometric Si3N4 and Li-active anazotic SiNx coated porous Si (p-Si@SiN) for high-performance anodes in LIBs. The ant-nest-like porous Si consisting of 3D interconnected Si nano-ligaments and bicontinuous nanopores prevents pulverization and accommodates volume expansion during cycling. The Si3N4 offers mechanically protective coating to endow highly structural integrity and inhibit superfluous formation of SEI. The fast ion conducting Li3N generated in situ from lithiation of active SiNx facilitates Li ion transport. Consequently, the p-Si@SiN anode has appealing electrochemical properties such as a high capacity of 2180 mAh g-1 at 0.5 A g-1 with 84% capacity retention after 200 cycles and excellent rate capacity with discharge capacity of 721 mAh g-1 after 500 cycles at 5.0 A g-1. This work provides insights into the rational design of active/inactive nanocoating on Si-based anode materials for fast-charging and highly stable LIBs.

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Ligand engineering of perovskite quantum dots for efficient and stable solar cells Shanshan Ding, Mengmeng Hao, Tongen Lin, Yang Bai, Lianzhou Wang 2022, 69(6): 626-648.  DOI: 10.1016/j.jechem.2022.02.006 Abstract ( 4 )   PDF (9204KB) ( 3 )   Lead halide perovskite quantum dots (PQDs) have recently emerged as promising light absorbers for pho-tovoltaic application due to their extraordinary optoelectronic properties. Surface ligands are of utmost importance for the colloidal stability and property tuning of PQDs, while their highly dynamic binding nat-ure not only impedes further efficiency improvement of PQD-based solar cells but also induces intrinsic instability. Tremendous efforts have been made in ligand engineering with good hopes to solve such chal-lenging issues in the past few years. In this review, we first present a fundamental understanding of the role of surface ligands in PQDs, followed by a brief discussion and classification of various ligands that have the potential for improving the electronic coupling and stability of PQD solids. We then provide a critical over-view of recent advances in ligand engineering including the strategies of in-situ ligand engineering, post-synthesis/-deposition ligand-exchange, and interfacial engineering, and discuss their impacts on changing the efficiency and stability of perovskite QD solar cells (QDSCs). Finally, we give our perspectives on the future directions of ligand engineering towards more efficient and stable perovskite QDSCs.

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Enhanced stability and rate performance of zinc-doped cobalt hexacyanoferrate (CoZnHCF) by the limited crystal growth and reduced distortion Jihwan Kim, Seong-Hoon Yi, Li Li, Sang-Eun Chun 2022, 69(6): 649-658.  DOI: 10.1016/j.jechem.2022.01.034 Abstract ( 6 )   PDF (3564KB) ( 2 )   Cobalt hexacyanoferrate (CoHCF) is a potential cathode for aqueous Na-ion batteries due to its high the-oretical specific capacity (170 mAh g-1); however, its lower rate capability and cyclability limit its appli-cations. Structural distortion at a weak N-coordinated crystal field during cycling disintegrates Co, yielding an irreversible reaction. Different Zn amounts ranging 0-1 were added to the Co site to suppress the structural irreversibility of CoHCF, yielding Co1-xZnxHCF powder; this Zn (x ≤ 0.09) addition reduced the powder's dimension because the lower four coordination of Zn-N, not the six coordination of Co-N, limits the powder growth. Simultaneously, a small lattice parameter and interaxial angle (~90°) are obtained, implying that a narrower Co1—xZnxHCF inner structure is formed to accommodate Na ions. Moreover, the electronic conductivity of Co1—xZnxHCF gradually increased within 0-0.09 range. A smaller particle size with a high surface area leads to a near-surface-limited redox process, similar to a capacitive reaction. Both the surface-limited reaction and electronic conductivity enhances the reversibility due to the smaller charge transfer resistance at the electrode/electrolyte interface caused by Zn addition. Replacing redox-active Co with non-active Zn amount of 0.07 (Co0.93Zn0.07HCF) slightly reduces the speci-fic capacity from 127 to 119 mAh g-1 at 0.1 A g-1 due to the shrunken Co charging sites. Rate performance is enhanced by compromising the capacity and reduced distortion, resulting in 81% retention at a 20-times-faster charging rate. Notably, the Co0.93Zn0.07HCF sample exhibited the good stability while pre-serving 74% of the initial capacity at 0.5 A g-1 after 200 cycles.

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Passivating buried interface with multifunctional novel ionic liquid containing simultaneously fluorinated anion and cation yielding stable perovskite solar cells over 23% efficiency Deyu Gao, Liqun Yang, Xiaohui Ma, Xueni Shang, Chen Wang, Mengjia Li, Xinmeng Zhuang, Boxue Zhang, Hongwei Song, Jiangzhao Chen, Cong Chen 2022, 69(6): 659-666.  DOI: 10.1016/j.jechem.2022.02.016 Abstract ( 13 )   PDF (6813KB) ( 7 )   Interfacial defects and energy barrier would result in serious interfacial non-radiative recombination losses. In addition, the quality of perovskite films is highly dependent on deposition substrates. Consequently, there is an urgent desire to develop multifunctional interface modulators to manage the interface between electron transport layer and perovskite layer. Here, we report a multifunctional buried interface modulation strategy that 4-fluoro-phenylammonium tetrafluoroborate (FBABF4) consisting of simultaneously fluorinated anion and cation is inserted between SnO2 layer and perovskite layer. It is uncovered by time-of-flight secondary ion mass spectroscopy that the anion and cation in modifier are mainly located at this interface, which is put down to coordination bond of the fluorine atom on BF-4 with SnO2, and the hydrogen bond of the fluorine atom on FBA+ with formamidinium. This suggests that simul-taneous fluorination of anion and cation in the ionic liquid molecule is of crucial importance to amelio-rate interfacial contact through chemical linker. The interface modification approach enables the realization of interfacial defect passivation, interfacial energy band alignment modulation, and perovskite crystallization manipulation, which are translated into enhanced efficiency and stability as well as signif-icantly suppressed hysteresis. The multiple functions of FBABF4 endow the modified solar cells excellent photovoltaic performance with an efficiency exceeding 23% along with appealing long-term stability. This work highlights the critical role of fluorination strategy in engineering multifunctional organic salt mod-ulators for improving interfacial contact.

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Impact of In3+ cations on structure and electromagnetic state of M type hexaferrites Vitalii Alexandrovich Turchenko, Sergei Valentnovich Trukhanov, Vladmir Grigor'evich Kostishin, Francua Damay, Florance Porcher, Denis Sergeevich Klygach, Maxim Grigor'evich Vakhitov, Lyudmila Yur'evna Matzui, Olena Sergeevna Yakovenko, Bernat Bozzo, Ignasi Fina, Munirah Abdullah Almessiere, Yassine Slimani, Abdulhadi Baykal, Di Zhou, Alex Valentinovich Trukhanov 2022, 69(6): 667-676.  DOI: 10.1016/j.jechem.2021.12.027 Abstract ( 6 )   PDF (4113KB) ( 2 )   The solid solutions of In3+ doped M—type strontium hexaferrites were produced using a conventional solid-state reaction method, and Rietveld analysis of the neutron diffraction patterns was conducted. In3+ cations occupy octahedral (4fVI and 12 k) and tetrahedral (4fIV) positions (SG = P63/mmc (No. 194)). The average particle size is 837-650 nm. Curie tempearature (TC) of the compounds monoton-ically decreased down to ~ 520 K with increasing x. A frustrated magnetic state was detected from ZFC and FC magnetizations. saturation magnetization (Ms) and effective magnetocrystalline anisotropy coef-ficient (keff) were determined using the law of approach to saturation. A real permittivity (e/) maximum of ~ 3.3 at ~ 45.5 GHz and an imaginary permittivity (e//) of ~ 1.6 at ~ 42.3 GHz were observed for x = 0.1. A real permeability (l/) maximum of ~ 1.5 at ~ 36.2 GHz was observed for x = 0. AL// imag-inary permeability maximum of ~ 0.8 at ~ 38.3 GHz was observed for x = 0.1. The interpretation of the results is based on the type of dielectric polarization and the natural ferromagnetic resonance features.