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2023, Vol. 85, No. 10　Online: 15 October 2023

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Bioinspired urchin-like murray carbon nanostructure with protection shell for advanced lithium-sulfur batteries Ya-Wen Tian, Yong Yu, Liang Wu, Min Yan, Wen-Da Dong, Chen-Yang Wang, Hemdan S.H. Mohamed, Zhao Deng, Li-Hua Chen, Tawfique Hasan, Yu Li, Bao-Lian Su 2023, 85(10): 1-10.  DOI: 10.1016/j.jechem.2023.05.018 Abstract ( 23 )   PDF (10706KB) ( 22 )   Commercial application of lithium-sulfur (Li-S) batteries is hindered by the insulating nature of sulfur and the dissolution of polysulfides. Here, a bioinspired 3D urchin-like N-doped Murray’s carbon nanostructure (N-MCN) with interconnected micro-meso-macroporous structure and a polydopamine protection shell has been designed as an effective sulfur host for high-performance Li-S batteries. The advanced 3D hierarchically porous framework with the characteristics of the generalized Murray’s law largely improves electrolyte diffusion, facilitates electrons/ions transfer and provides strong chemisorption for active species, leading to the synergistic structural and chemical confinement of polysulfides. As a result, the obtained P@S/N-MCN electrode with high areal sulfur loading demonstrates high capacity at high current densities after long cycles. This work reveals that following the generalized Murray’s law is feasible to design high-performance sulfur cathode materials for potentially practical Li-S battery applications.

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Exploring catalytic behaviors of CoS2-ReS2 heterojunction by interfacial engineering Jianmin Yu, Yongteng Qian, Sohyeon Seo, Yang Liu, Huong T.D. Bui, Ngoc Quang Tran, Jinsun Lee, Ashwani Kumar, Hongdan Wang, Yongguang Luo, Xiaodong Shao, Yunhee Cho, Xinghui Liu, Min Gyu Kim, Hyoyoung Lee 2023, 85(10): 11-18.  DOI: 10.1016/j.jechem.2023.05.030 Abstract ( 4 )   PDF (9196KB) ( 4 )   Herein, a stable and efficient CoS2-ReS2 electrocatalyst is successfully constructed by using the different molar ratios of CoS2 on ReS2. The size and morphology of the catalysts are significantly changed after the CoS2 is grown on ReS2, providing regulation of the catalytic activity of ReS2. Particularly, the optimized CoS2-ReS2 shows superior electrocatalytic properties with a low voltage of 1.48 V at 20 mA cm-2 for overall water splitting in 1.0 M KOH, which is smaller than the noble metal-based catalysts (1.77 V at 20 mA cm-2). The XPS, XAS, and theoretical data confirm that the interfacial regulation of ReS2 by CoS2 can provide rich edge catalytic sites, which greatly optimizes the catalytic kinetics and drop the energy barrier for oxygen/hydrogen evolution reactions. Our results demonstrated that interfacial engineering is an efficient route for fabricating high-performance water splitting electrocatalysts.

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Modulating J-V hysteresis of planar perovskite solar cells and mini-modules via work function engineering Zenghua Wang, Bing Cai, Deyu Xin, Min Zhang, Xiaojia Zheng 2023, 85(10): 19-29.  DOI: 10.1016/j.jechem.2023.05.031 Abstract ( 4 )   PDF (10719KB) ( 1 )   Commercialization of perovskite solar cells (PSCs) requires the development of high-efficiency devices with none current density-voltage (J-V) hysteresis. Here, electron transport layers (ETLs) with gradual change in work function (WF) are successfully fabricated and employed as an ideal model to investigate the energy barriers, charge transfer and recombination kinetics at ETL/perovskite interface. The energy barrier for electron injection existing at ETL/perovskite is directly assessed by surface photovoltage microscopy, and the results demonstrate the tunable barriers have significant impact on the J-V hysteresis and performance of PSCs. By work function engineering of ETL, PSCs exhibit PCEs over 21% with negligible hysteresis. These results provide a critical understanding of the origin reason for hysteresis effect in planar PSCs, and clear reveal that the J-V hysteresis can be effectively suppressed by carefully tuning the interface features in PSCs. By extending this strategy to a modified formamidinium-cesium-rubidium (FA-Cs-Rb) perovskite system, the PCEs are further boosted to 24.18%. Moreover, 5 cm × 5 cm perovskite mini-modules are also fabricated with an impressive efficiency of 20.07%, demonstrating compatibility and effectiveness of our strategy on upscaled devices.

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Engineered nitrogen doping on VO2(B) enables fast and reversible zinc-ion storage capability for aqueous zinc-ion batteries Xin Gu, Juntao Wang, Xiaobin Zhao, Xin Jin, Yuzhe Jiang, Pengcheng Dai, Nana Wang, Zhongchao Bai, Mengdi Zhang, Mingbo Wu 2023, 85(10): 30-38.  DOI: 10.1016/j.jechem.2023.05.043 Abstract ( 9 )   PDF (9056KB) ( 3 )   Vanadium-based compounds with high theoretical capacities and relatively stable crystal structures are potential cathodes for aqueous zinc-ion batteries (AZIBs). Nevertheless, their low electronic conductivity and sluggish zinc-ion diffusion kinetics in the crystal lattice are greatly obstructing their practical application. Herein, a general and simple nitrogen doping strategy is proposed to construct nitrogen-doped VO2(B) nanobelts (denoted as VO2-N) by the ammonia heat treatment. Compared with pure VO2(B), VO2-N shows an expanded lattice, reduced grain size, and disordered structure, which facilitates ion transport, provides additional ion storage sites, and improves structural durability, thus presenting much-enhanced zinc-ion storage performance. Density functional theory calculations demonstrate that nitrogen doping in VO2(B) improves its electronic properties and reduces the zinc-ion diffusion barrier. The optimal VO2-N400 electrode exhibits a high specific capacity of 373.7 mA h g-1 after 100 cycles at 0.1 A g-1 and stable cycling performance after 2000 cycles at 5 A g-1. The zinc-ion storage mechanism of VO2-N is identified as a typical intercalation/de-intercalation process.

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Spontaneous decoration of ionic compounds at perovskite interfaces to achieve 23.38% efficiency with 85% fill factor in NiOX-based perovskite solar cells Geping Qu, Deng Wang, Xiaoyuan Liu, Ying Qiao, Danish Khan, Yinxin Li, Jie Zeng, Pengfei Xie, Yintai Xu, Peide Zhu, Limin Huang, Yang-Gang Wang, Baomin Xu, Zong-Xiang Xu 2023, 85(10): 39-48.  DOI: 10.1016/j.jechem.2023.05.035 Abstract ( 7 )   PDF (10431KB) ( 1 )   Inorganic hole transport materials, particularly NiOX, have shown considerable promise in boosting the efficiency and stability of perovskite solar cells. However, a major barrier to commercialization of NiOX-based perovskite solar cells with positive-intrinsic-negative architectures is their direct contact with the absorbing layer, which can lead to losses of photovoltage and fill factor. Furthermore, highly positive under-coordinated Ni cations degrade the perovskite at the interface. Here, we address these issues with the use of an ionic compound (QAPyBF4) as an additive to passivate defects throughout the perovskite layer and improve carrier conduction and interactions with under-coordinated Ni cations. Specifically, the highly electronegative inorganic anion [BF4]- interacts with the NiOx/perovskite interface to passivate under-coordinated cations (Ni≥3+). Accordingly, the decorated cells achieved a power conversion efficiency of 23.38% and a fill factor of 85.5% without a complex surface treatment or NiOX doping.

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1,3,5-Trifluorobenzene endorsed EC-free electrolyte for high-voltage and wide-temperature lithium-ion batteries Mingsheng Qin, Ziqi Zeng, Qiang Wu, Xiaowei Liu, Qijun Liu, Shijie Cheng, Jia Xie 2023, 85(10): 49-57.  DOI: 10.1016/j.jechem.2023.06.003 Abstract ( 9 )   PDF (9661KB) ( 8 )   Ethylene carbonate (EC) is susceptible to the aggressive chemistry of nickel-rich cathodes, making it undesirable for high-voltage lithium-ion batteries (LIBs). The arbitrary elimination of EC leads to better oxidative tolerance but always incurs interfacial degradation and electrolyte decomposition. Herein, an EC-free electrolyte is deliberately developed based on gradient solvation by pairing solvation-protection agent (1,3,5-trifluorobenzene, F3B) with propylene carbonate (PC)/methyl ethyl carbonate (EMC) formulation. F3B keeps out of inner coordination shell but decomposes preferentially to construct robust interphase, inhibiting solvent decomposition and electrode corrosion. Thereby, the optimized electrolyte (1.1 M) with wide liquid range (-70-77 °C) conveys decent interfacial compatibility and high-voltage stability (4.6 V for LiNi0.6Mn0.2Co0.2O2, NCM622), qualifying reliable operation of practical NCM/graphite pouch cell (81.1% capacity retention over 600 cycles at 0.5 C). The solvation preservation and interface protection from F3B blaze a new avenue for developing high-voltage electrolytes in next-generation LIBs.

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Low-content Pt-triggered the optimized d-band center of Rh metallene for energy-saving hydrogen production coupled with hydrazine degradatio Qiqi Mao, Wenxin Wang, Kai Deng, Hongjie Yu, Ziqiang Wang, You Xu, Xiaonian Li, Liang Wang, Hongjing Wang 2023, 85(10): 58-66.  DOI: 10.1016/j.jechem.2023.06.005 Abstract ( 9 )   PDF (10901KB) ( 5 )   Utilizing the hydrazine-assisted water electrolysis for energy-efficient hydrogen production shows a promising application, which relies on the development and design of efficient bifunctional electrocatalysts. Herein, we reported a low-content Pt-doped Rh metallene (Pt-Rhene) for hydrazine-assisted water electrolysis towards energy-saving hydrogen (H2) production, where the ultrathin metallene is constructed to provide enough favorable active sites for catalysis and improve atom utilization. Additionally, the synergistic effect between Rh and Pt can optimize the electronic structure of Rh for improving the intrinsic activity. Therefore, the required overpotential of Pt-Rhene is only 37 mV to reach a current density of -10 mA cm-2 in the hydrogen evolution reaction (HER), and the Pt-Rhene exhibits a required overpotential of only 11 mV to reach a current density of 10 mA cm-2 in the hydrazine oxidation reaction (HzOR). With the constructed HER-HzOR two-electrode system, the Pt-Rhene electrodes exhibit an extremely low voltage (0.06/0.19/0.28 V) to achieve current densities of 10/50/100 mA cm-2 for energy-saving H2 production, which greatly reduces the electrolysis energy consumption. Moreover, DFT calculations further demonstrate that the introduction of Pt modulates the electronic structure of Rh and optimizes the d-band center, thus enhancing the adsorption and desorption of reactant/intermediates in the electrocatalytic reaction.

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Structural optimization and performance trade-off strategies for semi-crystalline sulfonated poly(arylene ether ketone) membranes in high-concentration direct methanol fuel cells Di Liu, Yunji Xie, Zhe Zhao, Jinbao Li, Jinhui Pang, Zhenhua Jiang 2023, 85(10): 67-75.  DOI: 10.1016/j.jechem.2023.05.049 Abstract ( 4 )   PDF (7433KB) ( 2 )   Direct methanol fuel cells (DMFCs) have attracted extensive attention as promising next-generation energy conversion devices. However, commercialized proton exchange membranes (PEMs) hardly fulfill the demand of methanol tolerance for DMFCs employing high-concentration methanol solutions. Herein, we report a series of semi-crystalline poly(arylene ether ketone) PEMs with ultra-densely sulfonic-acid-functionalized pendants linked by flexible alkyl chains, namely, SL-SPEK-x (where x represents the molar ratio of the novel monomer containing multiple phenyl side chain to the bisfluoride monomers). The delicate structural design rendered SL-SPEK-x membranes with high crystallinity and well-defined nanoscale phase separation between hydrophilic and hydrophobic phases. The reinforcement from poly(ether ketone) crystals enabled membranes with inhibited dimensional variation and methanol penetration. Furthermore, microphase separation significantly enhanced proton conductivity. The SL-SPEK-12.5 membrane achieved the optimum trade-off between proton conductivity (0.182 S cm-1, 80 °C), water swelling (13.6%, 80 °C), and methanol permeability (1.6 × 10-7 cm2 s-1). The DMFC assembled by the SL-SPEK-12.5 membrane operated smoothly with a 10 M methanol solution, outputting a maximum power density of 158.3 mW cm-2, nearly twice that of Nafion 117 (94.2 mW cm-2). Overall, the novel structural optimization strategy provides the possibility of PEMs surviving in high-concentration methanol solutions, thus facilitating the miniaturization and portability of DMFC devices.

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Enabling high-efficiency ethanol oxidation on NiFe-LDH via deprotonation promotion and absorption inhibition Jiawei Shi, Huawei He, Yinghua Guo, Feng Ji, Jing Li, Yi Zhang, Chengwei Deng, Liyuan Fan, Weiwei Cai 2023, 85(10): 76-82.  DOI: 10.1016/j.jechem.2023.06.011 Abstract ( 7 )   PDF (6619KB) ( 8 )   Nucleophile oxidation reaction (NOR), represented by ethanol oxidation reaction (EOR), is a promising pathway to replace oxygen evolution reaction (OER). EOR can effectively reduce the driving voltage of hydrogen production in direct water splitting. In this work, large current and high efficiency of EOR on a Ni, Fe layered double hydroxide (NiFe-LDH) catalyst were simultaneously achieved by a facile fluorination strategy. F in NiFe-LDH can reduce the activation energy of the dehydrogenation reaction, thus promoting the deprotonation process of NiFe-LDH to achieve a lower EOR onset potential. It also weakens the absorption of OH- and nucleophile electrooxidation products on the surface of NiFe-LDH at a higher potential, achieving a high current density and EOR selectivity, according to density functional theory calculations. Based on our experiment results, the optimized fluorinated NiFe-LDH catalyst achieves a low potential of 1.386 V to deliver a 10 mA cm-2 EOR. Moreover, the Faraday efficiency is greater than 95%, with a current density ranging from 10 to 250 mA cm-2. This work provides a promising pathway for an efficient and cost-effective NOR catalyst design for economic hydrogen production.

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Eco-friendly glucose assisted structurally simplified high-efficiency tin-lead mixed perovskite solar cells Jiayu You, Hongyu Bian, Meng Wang, Xinghong Cai, Chunmei Li, Guangdong Zhou, Hao Lu, Changxiang Fang, Jia Huang, Yanqing Yao, Cunyun Xu, Qunliang Song 2023, 85(10): 83-90.  DOI: 10.1016/j.jechem.2023.06.014 Abstract ( 7 )   PDF (7193KB) ( 3 )   Achieving highly-efficient and stable perovskite solar cells (PSCs) with a simplified structure remains challenging, despite the tremendous potential for reducing preparation cost and facile processability by removing hole transport layer (HTL). In this work, eco-friendly glucose (Gl) as an interface modifier for HTL-free narrow bandgap tin-lead (Sn-Pb) PSCs is proposed. Gl not only enhances the wettability of the indium tin oxide to promote perovskite heterogeneous nucleation on substrate, but also realizes defect passivation by interacting with uncoordinated Pb2+ and Sn2+ in perovskite films. As a result, the quality of the perovskite films has been significantly improved, accompanied by reduced defects of bottom interface and optimized energy level structure of device, leading to an efficiency increase and a less nonradiative voltage loss of 0.102 V (for a bandgap of ∼1.26 eV). Consequently, the optimized PSC delivers an unprecedented efficiency over 21% with high open-circuit voltage and enhanced stability, outperforming the control device. This work demonstrates a cost-effective approach to develop simplified structure high efficiency HTL-free Sn-Pb PSC.

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Gel-state polybenzimidazole proton exchange membranes with flexible alkyl sulfonic acid side chains for a wider operating temperature range (25-240 °C) Taizhong Zhu, Danyi Zhu, Jiazhen Liang, Liang Zhang, Fei Huang, Lixin Xue 2023, 85(10): 91-101.  DOI: 10.1016/j.jechem.2023.05.045 Abstract ( 12 )   PDF (9097KB) ( 11 )   High-temperature proton exchange membrane fuel cells (HT-PEMFC) possess distinct technical advantages of high output power, simplified water/heat management, increased tolerance to fuel impurities and diverse fuel sources, within the temperature range of 120-200 °C. However, for practical automobile applications, it was crucial to broaden their low-temperature operating window and enable cold start-up capability. Herein, gel-state phosphoric acid (PA) doped sulfonated polybenzimidazole (PBI) proton exchange membranes (PEMs) were designed and synthesized via PPA sol-gel process and in-situ sultone ring-opening reactions with various proton transport pathways based on absorbed PA, flexible alkyl chain connected sulfonic acid groups and imidazole sites. The effects of flexible alkyl sulfonic acid side chain length and content on PA doping level, proton conductivity, and membrane stability under different temperature and relative humidity (RH) were thoroughly investigated. The prepared gel-state membranes contained a self-assembled lamellar and porous structure that facilitated the absorption of a large amount of PA with rapid proton transporting mechanisms. At room temperature, the optimized membrane exhibited a proton conductivity of 0.069 S cm-1, which was further increased to 0.162 and 0.358 S cm-1 at 80 and 200 °C, respectively, without additional humidification. The most significant contribution of this work was demonstrating the feasibility of gel-state sulfonated PBI membranes in expanding HT-PEMFC application opportunities over a wider operating range of 25 to 240 °C.

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Boosting C-C coupling to multicarbon products via high-pressure CO electroreduction Wenqiang Yang, Huan Liu, Yutai Qi, Yifan Li, Yi Cui, Liang Yu, Xiaoju Cui, Dehui Deng 2023, 85(10): 102-107.  DOI: 10.1016/j.jechem.2023.06.013 Abstract ( 8 )   PDF (6132KB) ( 8 )   Electrochemical CO reduction reaction (CORR) provides a promising approach for producing valuable multicarbon products (C2+), while the low solubility of CO in aqueous solution and high energy barrier of C-C coupling as well as the competing hydrogen evolution reaction (HER) largely limit the efficiency for C2+ production in CORR. Here we report an overturn on the Faradaic efficiency of CORR from being HER-dominant to C2+ formation-dominant over a wide potential window, accompanied by a significant activity enhancement over a Moss-like Cu catalyst via pressuring CO. With the CO pressure rising from 1 to 40 atm, the C2+ Faradaic efficiency and partial current density remarkably increase from 22.8% and 18.9 mA cm-2 to 89.7% and 116.7 mA cm-2, respectively. Experimental and theoretical investigations reveal that high pressure-induced high CO coverage on metallic Cu surface weakens the Cu-C bond via reducing electron transfer from Cu to adsorbed CO and restrains hydrogen adsorption, which significantly facilitates the C-C coupling while suppressing HER on the predominant Cu(111) surface, thereby boosting the CO electroreduction to C2+ activity.

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Cold plasma-activated Cu-Co catalysts with CN vacancies for enhancing CO2 electroreduction to low-carbon alcohol Junyi Peng, Qiang Zhang, Yang Zhou, Xiaohui Yang, Fang Guo, Junqiang Xu 2023, 85(10): 108-115.  DOI: 10.1016/j.jechem.2023.06.004 Abstract ( 5 )   PDF (8284KB) ( 5 )   Electrocatalytic CO2 reduction reaction to low-carbon alcohol is a challenging task, especially high selectivity for ethanol, which is mainly limited by the regulation of reaction intermediates and subsequent C-C coupling. A Cu-Co bimetallic catalyst with CN vacancies is successfully developed by H2 cold plasma toward a high-efficiency CO2RR into low-carbon alcohol. The Cu-Co PBA-VCN (Prussian blue analogues with CN vacancies) electrocatalyst yields methanol and ethanol as major products with a total low-carbon alcohol FE of 83.8% (methanol: 39.2%, ethanol: 44.6%) at -0.9 V vs. RHE, excellent durability (100 h) and a small onset potential of -0.21 V. ATR-SEIRAS (attenuated total internal reflection surface enhanced infrared absorption spectroscopy) and DFT (density functional theory) reveal that the steric hindrance of VCN can enhance the CO generation from *COOH, and the C-C coupling can also be increased by CO spillover on uniformly dispersed Cu atoms. This work provides a strategy for the design and preparation of electrocatalysts for CO2RR into low-carbon alcohol products and highlights the impact of catalyst steric hindrance to catalytic performance.

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Elucidating the promotion mechanism of the ternary cooperative heterostructure toward industrial-level urea oxidation catalysis Xiujuan Xu, Xiaotong Wei, Liangliang Xu, Minghua Huang, Arafat Toghan 2023, 85(10): 116-125.  DOI: 10.1016/j.jechem.2023.05.012 Abstract ( 13 )   PDF (8801KB) ( 5 )   From the perspective of electronic structure modulation, it is highly desirable to rationally design the active urea oxidation reaction (UOR) catalysts through interface engineering. The binary cooperative heterostructure systems have been shown significant enhancement for catalyzing UOR, but their performance still remains unsatisfactory for industrialization because of the unfavorable intermediate adsorption/desorption and deficient electron transfer channels. In response, taking the ternary cooperative Ni5P4/NiSe2/Ni3Se4 heterostructure as the proof-of-concept paradigm, a catalytic model is rationally put forward to elucidate the UOR promotion mechanism at the molecular level. The rod-like Ni5P4/NiSe2/Ni3Se4 nanoarrays with three-phase heterojunction are experimentally fabricated on Ni foam (named as Ni5P4/NiSe2/Ni3Se4/NF) via simple two-step processes. The density functional theory calculations disclose that construction of Ni5P4/NiSe2/Ni3Se4 heterostructure model not only induce charge redistribution at the interfacial region for creating innumerable electron transfer channels, but also endow it with a moderate d-band center that could help to build a balance between adsorption and desorption of diverse UOR intermediates. Benefiting from the unique rod-like nanoarrays with large specific surface area and the optimized electronic structure, the well-designed Ni5P4/NiSe2/Ni3Se4/NF could act as a robust catalyst for driving UOR at industrial-level current densities under tough environments, offering great potential for commercial applications.

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Unveiling the parasitic-reaction-driven surface reconstruction in Ni-rich cathode and the electrochemical role of Li2CO3 Jiyu Cai, Zhenzhen Yang, Xinwei Zhou, Bingning Wang, Ana Suzana, Jianming Bai, Chen Liao, Yuzi Liu, Yanbin Chen, Shunlin Song, Xuequan Zhang, Li Wang, Xiangming He, Xiangbo Meng, Niloofar Karami, Baasit Ali Shaik Sulaiman, Natasha A. Chernova, Shailesh Upreti, Brad Prevel, Feng Wang, Zonghai Chen 2023, 85(10): 126-136.  DOI: 10.1016/j.jechem.2023.05.048 Abstract ( 8 )   PDF (18206KB) ( 2 )   Nickel-rich transition-metal oxides are widely regarded as promising cathode materials for high-energy-density lithium-ion batteries for emerging electric vehicles. However, achieving high energy density in Ni-rich cathodes is accompanied by substantial safety and cycle-life obstacles. The major issues of Ni-rich cathodes at high working potentials are originated from the unstable cathode-electrolyte interface, while the underlying mechanism of parasitic reactions towards surface reconstructions of cathode materials is not well understood. In this work, we controlled the Li2CO3 impurity content on LiNi0.83Mn0.1Co0.07O2 cathodes using air, tank-air, and O2 synthesis environments. Home-built high-precision leakage current and on-line electrochemical mass spectroscopy experiments verify that Li2CO3 impurity is a significant promoter of parasitic reactions on Ni-rich cathodes. The rate of parasitic reactions is strongly correlated to Li2CO3 content and severe performance deterioration of Ni83 cathodes. The post-mortem characterizations via high-resolution transition electron microscope and X-ray photoelectron spectroscopy depth profiles reveal that parasitic reactions promote more Ni reduction and O deficiency and even rock-salt phase transformation at the surface of cathode materials. Our observation suggests that surface reconstructions have a strong affiliation to parasitic reactions that create chemically acidic environment to etch away the lattice oxygen and offer the electrical charge to reduce the valence state of transition metal. Thus, this study advances our understanding on surface reconstructions of Ni-rich cathodes and prepares us for searching for rational strategies.

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Unravelling the role of boron dopant in borocarbonitirde catalytic dehydrogenation reaction Xuefei Zhang, Yanbing Lu, Yingyi Han, Runping Feng, Zailai Xie 2023, 85(10): 137-143.  DOI: 10.1016/j.jechem.2023.05.039 Abstract ( 6 )   PDF (6719KB) ( 5 )   Borocarbonitride (BCN) materials are newly developed metal-free catalytic materials exhibiting high selectivity in oxidative dehydrogenation (ODH) of alkanes. However, the in-depth understandings on the role of boron (B) dopants and the intrinsic activities of -C=O and -B-OH still remain unknown. Herein, we report a series of BCN materials with regulable B content and surface oxygen functional groups via self-assembly and pyrolysis of guanine and boric acid. We found that the B/C ratio is the key parameter to determine the activity of ODH and product distribution. Among them, the high ethylbenzene conversion (∼57%) and styrene selectivity (∼83%) are achieved in ODH for B1CN. The styrene selectivity can be improved by increasing of B/C ratio and this value reaches near 100% for B5CN. Structural characterizations and kinetic measurements indicate that -C=O and -B-OH dual sites on BCN are real active sites of ODH reaction. The intrinsic activity of -C=O (5.556 × 10-4 s-1) is found to be 23.7 times higher than -B-OH (0.234 × 10-4 s-1) site. More importantly, we reveal that the deep oxidation to undesirable CO2 occurs on -C=O rather than -B-OH site, and B dopant in BCN materials can reduce the nucleophilicity of -C=O site to eliminate the CO2 emission. Overall, the present work provides a new insight on the structure-function relationship of the BCN catalytic systems.

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Unexpected Li displacement and suppressed phase transition enabling highly stabilized oxygen redox in P3-type Na layered oxide cathode Myungeun Choi, Hobin Ahn, Hyunyoung Park, Yongseok Lee, Jinho Ahn, Bonyoung Ku, Junseong Kim, Wonseok Ko, Jungmin Kang, Jung-Keun Yoo, Duho Kim, Jongsoon Kim 2023, 85(10): 144-153.  DOI: 10.1016/j.jechem.2023.06.009 Abstract ( 5 )   PDF (9093KB) ( 2 )   Oxygen redox is considered a new paradigm for increasing the practical capacity and energy density of the layered oxide cathodes for Na-ion batteries. However, severe local structural changes and phase transitions during anionic redox reactions lead to poor electrochemical performance with sluggish kinetics. Here, we propose a synergy of Li-Cu cations in harnessing the full potential of oxygen redox, through Li displacement and suppressed phase transition in P3-type layered oxide cathode. P3-type Na0.7[Li0.1Cu0.2Mn0.7]O2 cathode delivers a large specific capacity of ∼212 mA h g-1 at 15 mA g-1. The discharge capacity is maintained up to ∼90% of the initial capacity after 100 cycles, with stable occurrence of the oxygen redox in the high-voltage region. Through advanced experimental analyses and first-principles calculations, it is confirmed that a stepwise redox reaction based on Cu and O ions occurs for the charge-compensation mechanism upon charging. Based on a concrete understanding of the reaction mechanism, the Li displacement by the synergy of Li-Cu cations plays a crucial role in suppressing the structural change of the P3-type layered material under the oxygen redox reaction, and it is expected to be an effective strategy for stabilizing the oxygen redox in the layered oxides of Na-ion batteries.

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Tuning the charge distribution and crystal field of iron single atoms via iron oxide integration for enhanced oxygen reduction reaction in zinc-air batteries Feifei Zhang, Yinlong Zhu, Yijun Zhong, Jing Zou, Yu Chen, Lianhai Zu, Zhouyou Wang, Jack Jon Hinsch, Yun Wang, Lian Zhang, Zongping Shao, Huanting Wang 2023, 85(10): 154-163.  DOI: 10.1016/j.jechem.2023.06.007 Abstract ( 19 )   PDF (11472KB) ( 6 )   Metal-air batteries face a great challenge in developing efficient and durable low-cost oxygen reduction reaction (ORR) electrocatalysts. Single-atom iron catalysts embedded into nitrogen doped carbon (Fe-N-C) have emerged as attractive materials for potential replacement of Pt in ORR, but their catalytic performance was limited by the symmetrical electronic structure distribution around the single-atom Fe site. Here, we report our findings in significantly enhancing the ORR performance of Fe-N-C by moderate Fe2O3integration via the strong electronic interaction. Remarkably, the optimized catalyst (M-Fe2O3/FeSA@NC) exhibits excellent activity, durability and good tolerance to methanol, outperforming the benchmark Pt/C catalyst. When M-Fe2O3/FeSA@NC catalyst was used in a practical zinc-air battery assembly, peak power density of 155 mW cm-2and specific capacity of 762 mA h gZn-1 were achieved and the battery assembly has shown superior cycling stability over a period of 200 h. More importantly, theoretical studies suggest that the introduction of Fe2O3 can evoke the crystal field alteration and electron redistribution on single Fe atoms, which can break the symmetric charge distribution of Fe-N4 and thereby optimize the corresponding adsorption energy of intermediates to promote the O2 reduction. This study provides a new pathway to promote the catalytic performance of single-atom catalysts.

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A versatile strategy to activate self-sacrificial templated Li2MnO3 by defect engineering toward advanced lithium storage Jian-En Zhou, Yanhua Peng, Xiaoyan Sang, Chunlei Wu, Yiqing Liu, Zhijian Peng, Hong Ou, Yongbo Wu, Xiaoming Lin, Yuepeng Cai 2023, 85(10): 164-180.  DOI: 10.1016/j.jechem.2023.05.014 Abstract ( 5 )   PDF (26830KB) ( 2 )   Despite the dazzling theoretical capacity, the devasting electrochemical activity of Li2MnO3 (LMO) caused by the difficult oxidation of Mn4+ impedes its practical application as the lithium-ion battery (LIB) cathode. The efficacious activation of the Li2MnO3 by importing electrochemically active Mn3+ ions or morphological engineering is instrumental to its lithium storage activity and structural integrity upon cycling. Herein, we propose a conceptual strategy with metal-organic frameworks (MOFs) as self-sacrificial templates to prepare oxygen-deficient Li2MnO3 (Ov-LMO) for exalted lithium storage performance. Attributed to optimized morphological features, LMO materials derived from Mn-BDC (H2BDC = 1,4-dicarboxybenzene) delivered superior cycling/rate performances compared with their counterparts derived from Mn-BTC (H3BTC = 1,3,5-benzenetricarboxylicacid) and Mn-PTC (H4PTC = pyromellitic acid). Both experimental and theoretical studies elucidate the efficacious activation of primitive LMO materials toward advanced lithium storage by importing oxygen deficiencies. Impressively, Ov-LMO derived from Mn-BDC (Ov-BDC-LMO) delivered intriguing reversible capacities (179.2 mA h g-1 at 20 mA g-1 after 200 cycles and 100.1 mA h g-1 at 80 mA g-1 after 300 cycles), which can be attributed to the small particle size that shortens pathways for Li+/electron transport, the enhanced redox activity induced by abundant oxygen vacancies, and the optimized electronic configuration that contributes to the faster lithium diffusivity. This work provides insights into the rational design of LMO by morphological and atomic modulation to direct its activation and practical application as an advanced LIB cathode.

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Unraveling the heterogeneity of solid electrolyte interphase kinetically affecting lithium electrodeposition on lithium metal anode Mengyuan Zhou, Yaqi Liao, Longhui Li, Ruoyu Xiong, Guancheng Shen, Yifu Chen, Tianlun Huang, Maoyuan Li, Huamin Zhou, Yun Zhang 2023, 85(10): 181-190.  DOI: 10.1016/j.jechem.2023.06.008 Abstract ( 5 )   PDF (7701KB) ( 7 )   The stability and uniformity of solid electrolyte interphase (SEI) are critical for clarifying the origin of capacity fade and safety issues for lithium metal anodes (LMA). However, understanding the interplay of SEI heterogeneity and Li electrodeposition is limited by the coupling of complex electrochemistry and mechanics processes. Herein, the correlation between the SEI failure behavior and Li deposition morphology is investigated through a quantitative electrochemical-mechanical model. The local deformation and stress of SEI during Li electrodeposition identify that the heterogeneous interface between different components first fails. Compared with the well-known mechanical strength, component uniformity plays the most important role in the initial SEI failure and uneven Li deposition, and a relative component uniformity (p> 0.01) represents a proper balance to ensure the stability of the naturally heterogeneous SEI. Furthermore, the component regulation of SEI via the designed electrolyte experimentally demonstrates that improving component uniformity benefits SEI stability and the uniform Li electrodeposition for LMA, thereby increasing the capacity by ∼20% after 300 cycles. These fundamental understandings and proposed strategy can be not only used to guide the SEI optimization via the electrolyte regulation, but also extended to the rational designs of artificial SEI for high-performance LMA.

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Li+-ion bound crown ether functionalization enables dual promotion of dynamics and thermodynamics for ambient ammonia synthesis Qiyang Cheng, Sisi Liu, Mengfan Wang, Lifang Zhang, Yanzheng He, Jiajie Ni, Jingru Zhang, Chengwei Deng, Yi Sun, Tao Qian, Chenglin Yan 2023, 85(10): 191-197.  DOI: 10.1016/j.jechem.2023.06.012 Abstract ( 4 )   PDF (6157KB) ( 4 )   Electrosynthesis of ammonia from the reduction of nitrogen is still confronted with the limited supply of gas reactant in dynamics as well as high activation barrier in thermodynamics. Unfortunately, despite tremendous efforts devoted to electrocatalysts themselves, they still fail to tackle the above two challenges simultaneously. Herein, we employ a heterogeneous catalyst adlayer—composed of crown ethers associated with Li+ions—to achieve the dual promotion of dynamics and thermodynamics for ambient ammonia synthesis. Dynamically, the bound Li+ ions interact with the strong quadrupole moment of nitrogen, and trigger considerable reactant flux toward the catalyst. Thermodynamically, Li+ associated with the oxygen of crown ether achieves a higher density of states at the Fermi level for the catalyst, enabling effortless electron transfer from the catalysts to nitrogen and thus greatly reducing the activation barrier. As expected, the proof-of-concept system achieves an ammonia yield rate of 168.5 μg h-1mg-1 and a Faradaic efficiency of 75.3% at -0.3 V vs. RHE. This system-level approach opens up pathways for tackling the two key challenges that have limited the field of ammonia synthesis.

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The role of morphology on the electrochemical CO2 reduction performance of transition metal-based catalysts Umar Mustapha, Chidera C. Nnadiekwe, Maria Abdulkarim Alhaboudal, Umar Yunusa, Abdulhakam Shafiu Abdullahi, Ismail Abdulazeez, Ijaz Hussain, Saheed A. Ganiyu, Abdulaziz A. Al-Saadi, Khalid Alhooshani 2023, 85(10): 198-219.  DOI: 10.1016/j.jechem.2023.06.010 Abstract ( 21 )   PDF (25313KB) ( 12 )   The continued increase in population and the industrial revolution have led to an increase in atmospheric carbon dioxide (CO2) concentration. Consequently, developing and implementing effective solutions to reduce CO2 emissions is a global priority. The electrochemical CO2 reduction reaction (CO2RR) is strongly believed to be a promising alternative to fossil fuel-based technologies for the production of value-added chemicals. So far, the implementation of CO2RR is hindered by associated electrochemical reactions, such as low selectivity, hydrogen evolution reaction (HER), and additional overpotential induced in some cases. As a result, it is necessary to conduct a timely evaluation of the state-of-the-art strategies in CO2RR, with a focus on the engineering of the electrocatalytic systems. Catalyst morphology is one factor that plays a critical role in overcoming these drawbacks and significantly contributes to enhancing product selectivity and Faradaic efficiency (FE). This review article summarizes the recent advances in the rational design of electrocatalysts with various morphologies and the influence of these morphologies on CO2RR. To compare literature findings in a meaningful way, the article focuses on results reported under a well-defined period and considers the first three rows of the d-block metal catalysts. The discussion typically covers the design of nanostructured catalysts and the molecular-level understanding of morphology-performance relationship in terms of activity, selectivity, and stability during CO2 electrolysis. Among others, it would be convenient to recommend a comprehensive discussion on the morphologies of single metals and heterostructures, with a detailed emphasis on their impact on CO2 conversion.

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Progress on the mechanisms of Ru-based electrocatalysts for the oxygen evolution reaction in acidic media Yuanyuan Shi, Han Wu, Jiangwei Chang, Zhiyong Tang, Siyu Lu 2023, 85(10): 220-238.  DOI: 10.1016/j.jechem.2023.06.001 Abstract ( 5 )   PDF (17600KB) ( 1 )   Water electrolysis using proton-exchange membranes is one of the most promising technologies for carbon-neutral and sustainable energy production. Generally, the overall efficiency of water splitting is limited by the oxygen evolution reaction (OER). Nevertheless, a trade-off between activity and stability exists for most electrocatalytic materials in strong acids and oxidizing media, and the development of efficient and stable catalytic materials has been an important focus of research. In this view, gaining in-depth insights into the OER system, particularly the interactions between reaction intermediates and active sites, is significantly important. To this end, this review introduces the fundamentals of the OER over Ru-based materials, including the conventional adsorbate evolution mechanism, lattice oxygen oxidation mechanism, and oxide path mechanism. Moreover, the up-to-date progress of representative modifications for improving OER performance is further discussed with reference to specific mechanisms, such as tuning of geometric, electronic structures, incorporation of proton acceptors, and optimization of metal-oxygen covalency. Finally, some valuable insights into the challenges and opportunities for OER electrocatalysts are provided with the aim to promote the development of next-generation catalysts with high activity and excellent stability.

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Tuning the electrochemical behaviors of N-doped LiMnxFe1-xPO4/C via cation engineering with metal-organic framework-templated strategy Yilin Li, Zhaohui Xu, Xinyu Zhang, Zhenyu Wu, Jian-En Zhou, Jinjiang Zhang, Xiaoming Lin 2023, 85(10): 239-253.  DOI: 10.1016/j.jechem.2023.06.015 Abstract ( 9 )   PDF (23995KB) ( 6 )   LiFePO4, as a prevailing cathode material for lithium-ion batteries (LIBs), still encounters issues such as intrinsic poor electronic conductivity, inferior Li-ion diffusion kinetic, and two-phase transformation mechanism involving substantial structural rearrangements, resulting in unsatisfactory rate performance. Carbon coating, cation doping, and morphological control have been widely employed to reconcile these issues. Inspired by these, we propose a synthetic route with metal-organic frameworks (MOFs) as self-sacrificial templates to simultaneously realize shape modulation, Mn doping, and N-doped carbon coating for enhanced electrochemical performances. The as-synthesized LiMnxFe1-xPO4/C (x = 0, 0.25, and 0.5) deliver tunable electrochemical behaviors induced by the MOF templates, among which LiMn0.25Fe0.75PO4/C outperforms its counterparts in cyclability (164.7 mA h g-1 after 200 cycles at 0.5 C) and rate capability (116.3 mA h g-1 at 10 C). Meanwhile, the ex-situ XRD reveals a dominant single-phase solid solution mechanism of LiMn0.25Fe0.75PO4/C during delithiation, contrary to the pristine LiFePO4, without major structural reconstruction, which helps to explain the superior rate performance. Furthermore, the density functional theory (DFT) calculations verify the effects of Mn doping and embody the superiority of LiMn0.25Fe0.75PO4/C as a LIB cathode, which well supports the experimental observations. This work provides insightful guidance for the design of tunable MOF-derived mixed transition-metal systems for advanced LIBs.

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Graphene quantum dots as sulfiphilic and lithiophilic mediator toward high stability and durable life lithium-sulfur batteries Chaojiang Fan, Rong Yang, Yong Huang, Lei Mao, Yuanyuan Yang, Le Gong, Xin Dong, Yinglin Yan, Yiming Zou, Lisheng Zhong, Yunhua Xu 2023, 85(10): 254-266.  DOI: 10.1016/j.jechem.2023.06.030 Abstract ( 5 )   PDF (23854KB) ( 1 )   The development of lithium-sulfur (Li-S) battery as one of the most attractive energy storage systems among lithium metal batteries is seriously hindered by low sulfur utilization, poor cycle stability and uneven redeposition of Li anode. It is necessary to propose strategies to address the problems as well as improve the electrochemical performance. One of the effective solutions is to improve the sulfiphilicity of sulfur cathode and the lithiophilicity of the Li anode. Herein, we reported that a synergistic functional separator (graphene quantum dots (GQDs)-polyacrylonitrile (PAN) @polypropylene (PP) separator) improved the electrochemical activity of sulfur cathode as well as the stability of Li anode. GQDs induced uniform Li+ nucleation and deposition, which slowed down the passivation of Li anode and avoided short-circuit. Further, three-dimensional network constructed by electrospinning nanofibers and the polar functional groups of GQDs could both effectively inhibit the shuttle of LiPSs and improve the sulfur utilization. The stability of Li-S battery was improved by the synergistic effect. In addition, GQDs and electrospinning nanofibers protector increased lifetime of separators. Benefiting from the unique design strategy, Li//Li symmetric battery with GQDs-PAN@PP separators exhibited stably cycling for over 600 h. More importantly, the Li-S full batteries based GQDs-PAN@PP separators enabled high stability and desirable sulfur electrochemistry, including high reversibility of 558.09 mA h g-1 for 200 cycles and durable life with a low fading rate of 0.075% per cycle after 500 cycles at 0.5 C. Moreover, an impressive areal capacity of 3.23 mA h cm-2 was maintained under high sulfur loading of 5.10 mg cm-2. This work provides a new insight for modification separator to improve the electrochemical performance of Li-S/Li metal batteries.

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Self-supported ultrathin NiCo layered double hydroxides nanosheets electrode for efficient electrosynthesis of formate Haoyuan Chi, Jianlong Lin, Siyu Kuang, Minglu Li, Hai Liu, Qun Fan, Tianxiang Yan, Sheng Zhang, Xinbin Ma 2023, 85(10): 267-275.  DOI: 10.1016/j.jechem.2023.06.024 Abstract ( 4 )   PDF (9838KB) ( 2 )   Electrochemical CO2 reduction into energy-carrying compounds, such as formate, is of great importance for carbon neutrality, which however suffers from high electrical energy input and liquid products crossover. Herein, we fabricated self-supported ultrathin NiCo layered double hydroxides (LDHs) electrodes as anode for methanol electrooxidation to achieve a high formate production rate (5.89 mmol h-1 cm-2) coupled with CO2 electro-reduction at the cathode. A total formate faradic efficiency of both anode for methanol oxidation and cathode for CO2 reduction can reach up to 188% driven by a low cell potential of only 2.06 V at 100 mA cm-2 in membrane-electrode assembly (MEA). Physical characterizations demonstrated that Ni3+ species, formed on the electrochemical oxidation of Ni-containing hydroxide, acted as catalytically active species for the oxidation of methanol to formate. Furthermore, DFT calculations revealed that ultrathin LDHs were beneficial for the formation of Ni3+ in hydroxides and introducing oxygen vacancy in NiCo-LDH could decrease the energy barrier of the rate-determining step for methanol oxidation. This work presents a promising approach for fabricating advanced electrodes towards electrocatalytic reactions.

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Enhanced rate and specific capacity in nanorod-like core-shell crystalline NiMoO4@amorphous cobalt boride materials enabled by Mott-Schottky heterostructure as positive electrode for hybrid supercapacitors Jing-Feng Hou, Jian-Fei Gao, Ling-Bin Kong 2023, 85(10): 276-287.  DOI: 10.1016/j.jechem.2023.06.023 Abstract ( 5 )   PDF (23491KB) ( 1 )   The supercapacitor electrode materials suffer from structure pulverization and sluggish electrode kinetics under high current rates. Herein, a unique NiMoO4@Co-B heterostructure composed of highly conductive Co-B nanoflakes and a semiconductive NiMoO4 nanorod is designed as an electrode material to exert the energy storage effect on supercapacitors. The formed Mott-Schottky heterostructure is helpful to overcome the ion diffusion barrier and charge transfer resistance during charging and discharging. Moreover, this crystalline-amorphous heterogeneous phase could provide additional ion storage sites and better strain adaptability. Remarkably, the optimized NiMoO4@Co-B hierarchical nanorods (the mass ratio of NiMoO4/Co-B is 3:1) present greatly enhanced electrochemical characteristics compared with other components, and show superior specific capacity of 236.2 mA h g-1 at the current density of 0.5 A g-1, as well as remarked rate capability. The present work broadens the horizons of advanced electrode design with distinct heterogeneous interface in other energy storage and conversion field.

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Combining descriptor-based analyses and mean-field modeling of the electrochemical interface to comprehend trends of catalytic processes at the solid/liquid interface Kai S. Exner 2023, 85(10): 288-290.  DOI: 10.1016/j.jechem.2023.06.025 Abstract ( 4 )   PDF (990KB) ( 2 )   Electrocatalysis is undergoing a renaissance due to its central importance for a sustainable energy economy, relying on green (electro-)chemical processes to harvest, convert, and store energy. Theoretical considerations by electronic structure methods are key to identify potential material motifs for electrocatalytic processes at the solid/ liquid interface. Most commonly, heuristic concepts in the realm of materials screening by the compilation of volcano plots are used, which rely on a plethora of simplifications and approximations of the complex electrochemical interface. While the investigation of the catalytic processes at the solid/ liquid interface mainly relies on descriptor-based approaches, in the present future article it is discussed that the inclusion of the liquid part of the interface by mean-field models is crucial to elevate screening approaches to the next level.

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Promotion effects of alkali metals on iron molybdate catalysts for CO2 catalytic hydrogenation Yong Zhou, Aliou Sadia Traore, Deizi V. Peron, Alan J. Barrios, Sergei A. Chernyak, Massimo Corda, Olga V. Safonova, Achim Iulian Dugulan, Ovidiu Ersen, Mirella Virginie, Vitaly V. Ordomsky, Andrei Y. Khodakov 2023, 85(10): 291-300.  DOI: 10.1016/j.jechem.2023.06.019 Abstract ( 3 )   PDF (8577KB) ( 2 )   CO2 hydrogenation is an attractive way to store and utilize carbon dioxide generated by industrial processes, as well as to produce valuable chemicals from renewable and abundant resources. Iron catalysts are commonly used for the hydrogenation of carbon oxides to hydrocarbons. Iron-molybdenum catalysts have found numerous applications in catalysis, but have been never evaluated in the CO2 hydrogenation. In this work, the structural properties of iron-molybdenum catalysts without and with a promoting alkali metal (Li, Na, K, Rb, or Cs) were characterized using X-ray diffraction, hydrogen temperature-programmed reduction, CO2 temperature-programmed desorption, in-situ 57Fe Mossbauer spectroscopy and operando X-ray adsorption spectroscopy. Their catalytic performance was evaluated in the CO2 hydrogenation. During the reaction conditions, the catalysts undergo the formation of an iron (II) molybdate structure, accompanied by a partial reduction of molybdenum and carbidization of iron. The rate of CO2 conversion and product selectivity strongly depend on the promoting alkali metals, and electronegativity was identified as an important factor affecting the catalytic performance. Higher CO2 conversion rates were observed with the promoters having higher electronegativity, while low electronegativity of alkali metals favors higher light olefin selectivity.

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Interfacial electronic coupling of V-doped Co2P with high-entropy MXene reduces kinetic energy barrier for efficient overall water splitting Wansen Ma, Zeming Qiu, Jinzhou Li, Liwen Hu, Qian Li, Xuewei Lv, Jie Dang 2023, 85(10): 301-309.  DOI: 10.1016/j.jechem.2023.06.017 Abstract ( 4 )   PDF (9129KB) ( 3 )   Developing efficient, low-cost non-noble metal-based bifunctional catalysts to achieve excellent hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) kinetics in alkaline media is challenging but very meaningful. However, improving the electronic structure of the catalyst to optimize the adsorption of intermediates and reduce the reaction energy barrier is the key to improve the reaction efficiency. Herein, a V-doped Co2P coupled with high-entropy MXene heterostructure catalyst (V-Co2P@HE) was prepared by a two-step electrodeposition and controlled phosphorization process. The analyses of X-ray absorption spectroscopy, X-ray photoelectron spectroscopy and theoretical calculations jointly show that the introduction of V and the strong electron coupling between the two components optimize the adsorption energy of water molecules and reaction intermediates. Benefiting from the abundant active sites and optimizing intermediate adsorption energy and heterogeneous interface electronic structure, V-Co2P@HE has excellent HER and OER activity and long-term stability under alkaline condition. In particular, when assembled as cathode and anode, the bifunctional V-Co2P@HE catalyst can drive a current density of 10 mA cm-2 with only 1.53 V. This work provides new strategies for the application of high-entropy MXene and the design of novel non-noble metal-based bifunctional electrolytic water catalysts.

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Depleted uranium oxide supported nickel catalyst for autothermal CO2 methanation in non-adiabatic reactor under induction heating Lai Truong-Phuoc, Jean-Mario Nhut, Loïc Vidal, Cuong Duong-Viet, Sécou Sall, Corinne Petit, Christophe Sutter, Mehdi Arab, Alex Jourdan, Cuong Pham-Huu 2023, 85(10): 310-323.  DOI: 10.1016/j.jechem.2023.06.035 Abstract ( 7 )   PDF (18775KB) ( 4 )   Undoped nickel-based catalysts supported on depleted uranium oxide allow one to carry out CO2 methanation process under extremely low reaction temperature under atmospheric pressure and powered by a contactless induction heating. By adjusting the reaction conditions, the catalyst is able to perform CO2 methanation reaction under autothermal process operated inside a non-adiabatic reactor, without any external energy supply. Such autothermal process is possible thanks to the high apparent density of the UOx which allows one to confine the reaction heat in a small catalyst volume in order to confine the exothermicity of the reaction inside the catalyst and to operate the reaction at equilibrium heat in-heat out. Such autothermal operation mode allows one to significantly reduce the complexity of the process compared to that operated using adiabatic reactor, where complete insulation is required to prevent heat disequilibrium, in order to reduce as much as possible, the heat exchange with the external medium. The catalyst displays an extremely high stability as a function of time on stream as no apparent deactivation. It is expected that such new catalyst with unprecedented catalytic performance could open new era in the field of heterogeneous catalysis where traditional supports show their limitations to operate catalytic processes under severe reaction conditions.

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Ce & F multifunctional modification improves the electrochemical performance of LiCoO2 at 4.60 V Jiangli Feng, Chenhui Wang, Hailin Lei, Songtao Liu, Jing Liu, You Han, Jinli Zhang, Wei Li 2023, 85(10): 324-334.  DOI: 10.1016/j.jechem.2023.06.033 Abstract ( 3 )   PDF (17524KB) ( 1 )   Lithium cobalt oxide (LiCoO2) is proverbially employed as cathode materials of lithium-ion batteries attributed to the high theoretical capacity, and currently, it is developing towards higher cut-off voltages in the pursuit of higher energy density. However, it suffers from serious structural degradation and surface side reactions, in particular, at the voltage above 4.60 V, leading to rapid decay of the battery life. Taking into account the desirable oxygen buffering property and the fast ion mobility characteristic of cerium oxide fluoride, in this work, we prepared Ce & F co-modified LiCoO2 by using the precursors of Ce(NO3)3·6H2O and NH4F, and evaluated the electrochemical performance under voltages exceeding 4.60 V. The results indicated that the modified samples have multiphase heterostructure of surface CeO2-x and unique Ce—O—F solid solution phase. At 3.0-4.60 V and 25 °C, the preferred sample LCO-0.5Ce-0.3F has a high initial discharge specific capacity of 221.9 mA h g-1 at 0.1 C, with the retention of 80.3% and 89.6% after 300 cycles at 1 and 5 C, comparing with the pristine LCO (56.4% and 22.6%). And at 3.0-4.65 V, its retention is 64.0% after 300 cycles at 1 C, versus 8.5% of the pristine LCO. Through structural characterizations and DFT calculations, it suggests that Ce4+ & F- co-doping suppresses the H3 to H1/3 irreversible phase transition, stabilizes the lattice structure, and reduces the redox activity of the lattice oxygen by modulating the Co 3d-O 2p energy band, consequently improving the electrochemical performance of LiCoO2 at high voltages.

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Cross-linked polyelectrolyte reinforced SnO2electron transport layer for robust flexible perovskite solar cells Zhihao Li, Zhi Wan, Chunmei Jia, Meng Zhang, Meihe Zhang, Jiayi Xue, Jianghua Shen, Can Li, Chao Zhang, Zhen Li 2023, 85(10): 335-342.  DOI: 10.1016/j.jechem.2023.06.026 Abstract ( 8 )   PDF (7147KB) ( 4 )   SnO2 electron transport layer (ETL) is a vital component in perovskite solar cells (PSCs), due to its excellent photoelectric properties and facile fabrication process. In this study, we synthesized a water-soluble and adhesive polyelectrolyte with ethanolamine (EA) and poly-acrylic acid (PAA). The linear PAA was crosslinked by EA, forming a 3D network that stabilized the SnO2 nanoparticle dispersion. An organic-inorganic hybrid ETL is developed by introducing the cross-linked PAA-EA into SnO2 ETL, which prevents nano particle agglomeration and facilitates uniform SnO2 film formation with fewer defects. Additionally, the PAA-EA-modified SnO2 facilitated a uniform and compact perovskite film, enhancing the interface contact and carrier transport. Consequently, the PAA-EA-modified PSCs exhibited excellent PCE of 24.34% and 22.88% with high reproducibility for areas of 0.045 and 1.00 cm2, respectively. Notably, owing to structure reinforce effect of PAA-EA in SnO2 ETL, flexible device demonstrated an impressive PCE of 23.34% while maintaining 90.1% of the initial PCE after 10,000 bending cycles with a bending radius of 5 mm. This successful approach of polyelectrolyte reinforced hybrid organic-inorganic ETL displays great potential for flexible, large-area PSCs application.

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Butyl ether as Co-diluent in medium-concentrated electrolyte for Li-S battery Xirui Kong, Yayun Zheng, Lang He, Du Wang, Yan Zhao 2023, 85(10): 343-347.  DOI: 10.1016/j.jechem.2023.07.004 Abstract ( 9 )   PDF (6943KB) ( 4 )

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Hydrogenase as the basis for green hydrogen production and utilization Haishuo Ji, Lei Wan, Yanxin Gao, Ping Du, Wenjin Li, Hang Luo, Jiarui Ning, Yingying Zhao, Huangwei Wang, Lixin Zhang, Liyun Zhang 2023, 85(10): 348-362.  DOI: 10.1016/j.jechem.2023.06.018 Abstract ( 19 )   PDF (12832KB) ( 9 )   Hydrogenase is a paradigm of highly efficient biocatalyst for H2 production and utilization evolved in nature. A dilemma is that despite the high activity and efficiency expected for hydrogenases as promising catalysts for the hydrogen economy, the poor oxygen tolerance and low yield of hydrogenases largely hinder their practical application. In these years, the enigmas surrounding hydrogenases regarding their structures, oxygen tolerance, mechanisms for catalysis, redox intermediates, and proton-coupled electron transfer schemes have been gradually elucidated; the schemes, which can well couple hydrogenases with other highly efficient (in)organic and biological catalysts to build novel reactors and drive valuable reactions, make it possible for hydrogenases to find their niches. To see how scientists put efforts to tackle this issue and design novel reactors in the fields where hydrogenases play crucial roles, in this review, recent advances were summarized, including different strategies for protecting enzyme molecules from oxygen, enzyme-based assembling systems for H2 evolution in the photoelectronic catalysis, enzymatic biofuel cells for H2 utilization and storage and the efficient electricity-hydrogen-carbohydrate cycle for high-purity hydrogen and biofuel automobiles. Limitations and future perspectives of hydrogenase-based applications in H2 production and utilization with great impact are discussed. In addition, this review also provides a new perspective on the use of biohydrogen in healthcare beyond energy.

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Fluoridation routes, function mechanism and application of fluorinated/fluorine-doped nanocarbon-based materials for various batteries: A review Weicui Liu, Nanping Deng, Gang Wang, Ruru Yu, Xiaoxiao Wang, Bowen Cheng, Jingge Ju, Weimin Kang 2023, 85(10): 363-393.  DOI: 10.1016/j.jechem.2023.06.020 Abstract ( 8 )   PDF (26001KB) ( 4 )   With the popularity and widespread applications of electronics, higher demands are being placed on the performance of battery materials. Due to the large difference in electronegativity between fluorine and carbon atoms, doping fluorine atoms in nanocarbon-based materials is considered an effective way to improve the performance of used battery. However, there is still a blank in the systematic review of the mechanism and research progress of fluorine-doped nanostructured carbon materials in various batteries. In this review, the synthetic routes of fluorinated/fluorine-doped nanocarbon-based (CFx) materials under different fluorine sources and the function mechanism of CFxin various batteries are reviewed in detail. Subsequently, judging from the dependence between the structure and electrochemical performance of nanocarbon sources, the progress of CFx based on different dimensions (0D-3D) for primary battery applications is reviewed and the balance between energy density and power density is critically discussed. In addition, the roles of CFx materials in secondary batteries and their current applications in recent years are summarized in detail to illustrate the effect of introducing F atoms. Finally, we envisage the prospect of CFx materials and offer some insights and recommendations to facilitate the further exploration of CFx materials for various high-performance battery applications.

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Strategically designing layered two-dimensional SnS2-based hybrid electrodes: A futuristic option for low-cost supercapacitors Susmi Anna Thomas, Jayesh Cherusseri 2023, 85(10): 394-417.  DOI: 10.1016/j.jechem.2023.06.037 Abstract ( 5 )   PDF (35047KB) ( 1 )   Supercapacitors are promising energy storage devices in current century due to their high specific capacitance, cyclic stability, high power density, and high voltage rating. Due to their excellent electrochemical properties, supercapacitors are invariably used in a multitude of applications ranging from portable electronics to electric vehicles. The electrochemical performance of a supercapacitor mainly depends on the type of electrode-active material used in it. Thereby a careful selection is mandatory to achieve the excellency. Nanostructured electrode-active materials such as carbon nanomaterials, transition metal oxides, transition metal dichalcogenides (TMDs), electronically conducting polymers, etc. are invariably used for supercapacitor application. Among these, TMDs have received great interest, particularly transition metal disulfides such as molybdenum disulfide, tin disulfide (SnS2), etc. Tin is abundant on the earth with excellent charge storage capabilities, attracted great scientific interest for application as electrode materials in supercapacitors. Good electronic conductivity, long cycling life and low-cost are its added advantages. Herein, we discuss the recent trends in layered two-dimensional (2D) SnS2-based electrodes to develop low-cost supercapacitors. Initially, their crystal structure, basic properties, synthesis methods are discussed. Further, strategically designing electrode nanostructures to achieve excellent electrochemical performance is reviewed then after. This includes material design in terms of morphology, pore-size, and shape as well as preparation of 2D SnS2-based nanocomposite electrodes. Furthermore, the challenges and future perspectives of 2D SnS2-based supercapacitors are included.

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Fat, oil, and grease as new feedstock towards bioelectrogenesis in microbial fuel cells: Microbial diversity, metabolic pathways, and key enzymes Monika Sharma, Mohammed Jalalah, Saeed A. Alsareii, Farid A. Harraz, Abdulrhman A. Almadiy, Nandini Thakur, El-Sayed Salama, Xiangkai Li 2023, 85(10): 418-429.  DOI: 10.1016/j.jechem.2023.06.028 Abstract ( 6 )   PDF (7215KB) ( 4 )   Microbial fuel cells (MFCs) are a well-known technology used for bioelectricity production from the decomposition of organic waste via electroactive microbes. Fat, oil, and grease (FOG) as a new substrate in the anode and microalgae in the cathode were added to accelerate the electrogenesis. The effect of FOG concentrations (0.1%, 0.5%, 1%, and 1.5%) on the anode chamber was investigated. The FOG degradation, volatile fatty acid (VFAs) production, and soluble chemical oxygen demand along with voltage output kinetics were analyzed. Moreover, the microbial community analysis and active functional enzymes were also evaluated. The maximum power and current density were observed at 0.5% FOG which accounts for 96 mW m-2 (8-folds enhancement) and 560 mA m-2 (3.7-folds enhancement), respectively. The daily voltage output enhanced upto 2.3-folds with 77.08% coulombic efficiency under 0.5% FOG, which was the highest among all the reactors. The 0.5% FOG was degraded >85%, followed by a 1% FOG-loaded reactor. The chief enzymes in β-oxidation and electrogenesis were acetyl-CoA C-acetyltransferase, riboflavin synthase, and riboflavin kinase. The identified enzymes symbolize the presence of Clostridium sp. (>15%) and Pseudomonas (>10%) which served as electrochemical active bacteria (EAB). The major metabolic pathways involved in electrogenesis and FOG degradation were fatty acid biosynthesis and glycerophospholipid metabolism. Utilization of lipidic-waste (such as FOG) in MFCs could be a potential approach for simultaneous biowaste utilization and bioenergy generation.

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Advanced heterostructure of Pd nanosheets@Pt nanoparticles boosts methanol electrooxidation Jie Li, Cheng Wang, Yuefan Zhang, Shinichi Hata, Kewang Zhang, Changqing Ye, Yukihide Shiraishi, Yukou Du 2023, 85(10): 430-438.  DOI: 10.1016/j.jechem.2023.06.031 Abstract ( 6 )   PDF (12306KB) ( 2 )   Heterostructures have emerged as elaborate structures to improve catalytic activity owing to their combined surface and distinct inverse interface. However, fabricating advanced nanocatalysts with facet-dependent interface remains an unexploited and promising area. Herein, we render the controlled growth of Pt nanoparticles (NPs) on Pd nanosheets (NSs) by regulating the reduction kinetics of Pt2+ with solvents. Specifically, the fast reduction kinetic makes the Pt NPs uniformly deposited on the Pd NSs (U-Pd@Pt HS), while the slow reduction kinetic leads to the preferential growth of Pt NPs on the edge of the Pd NSs (E-Pd@Pt HS). Density functional theory calculations demonstrate that Pd (111)-Pt interface in U-Pd@Pt HS induces the electron-deficient status of Pd substrates, triggering the d-band center downshift and amplifying the Pd-Pt intermetallic interaction. The synergy between the electronic effect and interfacial effect facilitates the removal of poisonous intermediates on U-Pd@Pt HS. By virtue of the Pd NSs@Pt NPs interface, the heterostructure achieves exceptional methanol oxidation reaction activity as well as improved durability. This study innovatively proposes heterostructure engineering with facet-dependent interfacial modulation, offering instructive guidelines for the rational design of versatile heterocatalysts.

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Selective synthesis of nitrate from air using a plasma-driven gas-liquid relay reaction system Sibo Chen, Kai Mei, Yaru Luo, Liang-Xin Ding, Haihui Wang 2023, 85(10): 439-446.  DOI: 10.1016/j.jechem.2023.06.021 Abstract ( 9 )   PDF (3245KB) ( 6 )   The direct oxidation of nitrogen is a potential pathway to achieving the zero-carbon-emission synthesis of nitric acid or nitrate, because it does not involve ammonia synthesis and additional ammonia oxidation processes. However, the slow kinetics of nitrogen oxidation and the difficult selective control of oxidation products hinder the development of this process. In this study, a plasma-driven gas-liquid relay reaction system was developed to overcome these limitations. A typical feature of this reaction system is that it can efficiently generate NOx under plasma exposure; moreover, the specific anions in the absorption solution can be oxidized to strong oxidants capable of relay oxidation of low-valence nitrogen oxides. This feature allows for the deep oxidation of nitrogen, thus enabling the oxidation products of nitrogen to exist in high-valence states in the absorption solution. For experimental verification, we achieved the 100% selective synthesis of nitrate under plasma exposure, with air as the supply gas and a sodium sulfate solution as the absorption solution.

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Electrochemical hydrogen evolution efficiently boosted by interfacial charge redistribution in Ru/MoSe2 embedded mesoporous hollow carbon spheres Yubin Kuang, Wei Qiao, Fulin Yang, Ligang Feng 2023, 85(10): 447-454.  DOI: 10.1016/j.jechem.2023.06.022 Abstract ( 3 )   PDF (12906KB) ( 1 )   The strong metal-support interaction inducing combined effect plays a crucial role in the catalysis reaction. Herein, we revealed that the combined advantages of MoSe2, Ru, and hollow carbon spheres in the form of Ru nanoparticles (NPs) anchored on a two-dimensionally ordered MoSe2 nanosheet-embedded mesoporous hollow carbon spheres surface (Ru/MoSe2@MHCS) for the largely boosted hydrogen evolution reaction (HER) performance. The combined advantages from the conductive support, oxyphilic MoSe2, and Ru active sites imparted a strong synergistic effect and charge redistribution in the Ru periphery which induced high catalytic activity, stability, and kinetics for HER. Specifically, the obtained Ru/MoSe2@MHCS required a small overpotential of 25.5 and 38.4 mV to drive the kinetic current density of 10 mA cm-2 both in acid and alkaline media, respectively, which was comparable to that of the Pt/C catalyst. Experimental and theoretical results demonstrated that the charge transfer from MoSe2 to Ru NPs enriched the electronic density of Ru sites and thus facilitated hydrogen adsorption and water dissociation. The current work showed the significant interfacial engineering in Ru-based catalysts development and catalysis promotion effect understanding via the metal-support interaction.

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Photoelectrochemical CO2 electrolyzers: From photoelectrode fabrication to reactor configuration Jose Antonio Abarca, Guillermo Díaz-Sainz, Ivan Merino-Garcia, Angel Irabien, Jonathan Albo 2023, 85(10): 455-480.  DOI: 10.1016/j.jechem.2023.06.032 Abstract ( 3 )   PDF (6558KB) ( 3 )   The photoelectrochemical conversion of CO2 into value-added products emerges as an attractive approach to alleviate climate change. One of the main challenges in deploying this technology is, however, the development and optimization of (photo)electrodes and photoelectrolyzers. This review focuses on the fabrication processes, structure, and characterization of (photo)electrodes, covering a wide range of fabrication techniques, from rudimentary to automated fabrication processes. The work also highlights the most relevant features of (photo)electrodes, with special emphasis on how to measure and optimize them. Finally, the review analyses the integration of (photo)electrodes in different photoelectrolyzer architectures, analyzing the most recent research work that comprises photocathode, photoanode, photocathode-photoanode, and tandem photoelectrolyzer configurations to ideally achieve self-sustained CO2 conversion systems. Overall, comprehensive guidelines are provided for future advancements in developing effective devices for CO2 conversion, bridging the gap towards the use of sunlight as the unique energy input and practical applications.

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Pt-Te alloy nanowires towards formic acid electrooxidation reaction Bin Sun, Yu-Chuan Jiang, Qing-Ling Hong, Xue Liu, Fu-Min Li, Dong-Sheng Li, Yun Yang, Yu Chen 2023, 85(10): 481-489.  DOI: 10.1016/j.jechem.2023.06.027 Abstract ( 5 )   PDF (6733KB) ( 2 )   The high-performance anodic electrocatalysts is pivotal for realizing the commercial application of the direct formic acid fuel cells. In this work, a simple polyethyleneimine-assisted galvanic replacement reaction is applied to synthesize the high-quality PtTe alloy nanowires (PtTe NW) by using Te NW as an efficient sacrificial template. The existence of Te atoms separates the continuous Pt atoms, triggering a direct reaction pathway of formic acid electrooxidation reaction (FAEOR) at PtTe NW. The one-dimensional architecture and highly active sites have enabled PtTe NW to reveal outstanding electrocatalytic activity towards FAEOR with the mass/specific activities of 1091.25 mA mg-1/45.34 A m-2 at 0.643 V potential, which are 44.72/23.16 and 20.26/11.75 times bigger than those of the commercial Pt and Pd nanoparticles, respectively. Density functional theory calculations reveal that Te atoms optimize the electronic structure of Pt atoms, which decreases the adsorption capacity of CO intermediate and simultaneously improves the durability of PtTe NW towards FAEOR. This work provides the valuable insights into the synthesis and design of efficient Pt-based alloy FAEOR electrocatalysts.

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The role of copper in enhancing the performance of heteronuclear diatomic catalysts for the electrochemical CO2conversion to C1 chemicals Qi Zhao, Rachel Crespo-Otero, Devis Di Tommaso 2023, 85(10): 490-500.  DOI: 10.1016/j.jechem.2023.06.029 Abstract ( 11 )   PDF (3444KB) ( 7 )   Diatomic catalysts (DACs) with two adjacent metal atoms supported on graphene can offer diverse functionalities, overcoming the inherent limitations of single atom catalysts (SACs). In this study, density functional theory calculations were conducted to investigate the reactivity of the carbon dioxide (CO2) reduction reaction (CO2RR) on metal sites of both DACs and SACs, as well as their synergistic effects on activity and selectivity. Calculation of the Gibbs free energies of CO2RR and associated values of the limiting potentials to generate C1 products showed that Cu acts as a promoter rather than an active catalytic centre in the catalytic CO2 conversion on heteronuclear DACs (CuN4-MN4), improving the catalytic activity on the other metal compared to the related SAC MN4. Cu enhances the initial reduction of CO2 by promoting orbital hybridization between the key intermediate *COOH 2p-orbitals and the metals 3d-orbitals around the Fermi level. This degree of hybridization in the DACs CuN4-MN4 decreases from Fe to Co, Ni, and Zn. Our work demonstrates how Cu regulates the CO2RR performance of heteronuclear DACs, offering an effective approach to designing practical, stable, and high-performing diatomic catalysts for CO2 electroreduction.

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Is a catalyst always beneficial in plasma catalysis? Insights from the many physical and chemical interactions Björn Loenders, Roel Michiels, Annemie Bogaerts 2023, 85(10): 501-533.  DOI: 10.1016/j.jechem.2023.06.016 Abstract ( 10 )   PDF (14472KB) ( 7 )   Plasma-catalytic dry reforming of CH4 (DRM) is promising to convert the greenhouse gasses CH4 and CO2 into value-added chemicals, thus simultaneously providing an alternative to fossil resources as feedstock for the chemical industry. However, while many experiments have been dedicated to plasma-catalytic DRM, there is no consensus yet in literature on the optimal choice of catalyst for targeted products, because the underlying mechanisms are far from understood. Indeed, plasma catalysis is very complex, as it encompasses various chemical and physical interactions between plasma and catalyst, which depend on many parameters. This complexity hampers the comparison of experimental results from different studies, which, in our opinion, is an important bottleneck in the further development of this promising research field. Hence, in this perspective paper, we describe the important physical and chemical effects that should be accounted for when designing plasma-catalytic experiments in general, highlighting the need for standardized experimental setups, as well as careful documentation of packing properties and reaction conditions, to further advance this research field. On the other hand, many parameters also create many windows of opportunity for further optimizing plasma-catalytic systems. Finally, various experiments also reveal the lack of improvement in plasma catalysis compared to plasma-only, specifically for DRM, but the underlying mechanisms are unclear. Therefore, we present our newly developed coupled plasma-surface kinetics model for DRM, to provide more insight in the underlying reasons. Our model illustrates that transition metal catalysts can adversely affect plasma-catalytic DRM, if radicals dominate the plasma-catalyst interactions. Thus, we demonstrate that a good understanding of the plasma-catalyst interactions is crucial to avoiding conditions at which these interactions negatively affect the results, and we provide some recommendations for improvement. For instance, we believe that plasma-catalytic DRM may benefit more from higher reaction temperatures, at which vibrational excitation can enhance the surface reactions.

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Lithium-ion battery degradation trajectory early prediction with synthetic dataset and deep learning Mingqiang Lin, Yuqiang You, Jinhao Meng, Wei Wang, Ji Wu, Daniel-Ioan Stroe 2023, 85(10): 534-546.  DOI: 10.1016/j.jechem.2023.06.036 Abstract ( 7 )   PDF (12983KB) ( 4 )   Knowing the long-term degradation trajectory of Lithium-ion (Li-ion) battery in its early usage stage is critical for the maintenance of the battery energy storage system (BESS) in reality. Previous battery health diagnosis methods focus on capacity and state of health (SOH) estimation which can receive only the short-term health status of the cell. This paper proposes a novel degradation trajectory prediction method with synthetic dataset and deep learning, which enables to grasp the characterization of the cell’s health at a very early stage of Li-ion battery usage. A transferred convolutional neural network (CNN) is chosen to finalize the early prediction target, and the polynomial function based synthetic dataset generation strategy is designed to reduce the costly data collection procedure in real application. In this thread, the proposed method needs one full lifespan data to predict the overall degradation trajectories of other cells. With only the full lifespan cycling data from 4 cells and 100 cycling data from each cell in experimental validation, the proposed method shows a good prediction accuracy on a dataset with more than 100 commercial Li-ion batteries.

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Pyrometallurgical recycling of spent lithium-ion batteries from conventional roasting to synergistic pyrolysis with organic wastes Chao Pan, Yafei Shen 2023, 85(10): 547-561.  DOI: 10.1016/j.jechem.2023.06.040 Abstract ( 9 )   PDF (16505KB) ( 4 )   The synergistic pyrolysis has been increasingly used for recycling spent lithium-ion batteries (LIBs) and organic wastes (hydrogen and carbon sources), which are in-situ transformed into various reducing agents such as H2, CO, and char via carbothermal and/or gas thermal reduction. Compared with the conventional roasting methods, this “killing two birds with one stone” strategy can not only reduce the cost and energy consumption, but also realize the valorization of organic wastes. This paper concluded the research progress in synergistic pyrolysis recycling of spent LIBs and organic wastes. On the one hand, valued metals such as Li, Co, Ni, and Mn can be recovered through the pyrolysis of the cathode materials with inherent organic materials (e.g., separator, electrolyte) or graphite anode. During the pyrolysis process, the organic materials are decomposed into char and gases (e.g., CO, H2, and CH4) as reducing agents, while the cathode material is decomposed and then converted into Li2CO3 and low-valent transition metals or their oxides via in-situ thermal reduction. The formed Li2CO3 can be easily recovered by the water leaching process, while the formed transition metals or their oxides (e.g., Co, CoO, Ni, MnO, etc.) can be recovered by the reductant-free acid leaching or magnetic separation process. On the other hand, organic wastes (e.g., biomass, plastics, etc.) as abundant hydrogen and carbon sources can be converted into gas (e.g., H2, CO, etc.) and char via pyrolysis. The cathode materials are decomposed and subsequently reduced by the pyrolysis gas and char. In addition, the pyrolysis oil and gas can be upgraded by catalytic reforming with the active metals derived from cathode material. Finally, great challenges are proposed to promote this promising technology in the industrial applications.

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Ni-catalyzed carbon-carbon bonds cleavage of mixed polyolefin plastics waste Xiaoqin Si, Jiali Chen, Zhengwei Wang, Yue Hu, Zhiwen Ren, Rui Lu, Lu Liu, Jing Zhang, Liwei Pan, Rui Cai, Fang Lu 2023, 85(10): 562-569.  DOI: 10.1016/j.jechem.2023.07.012 Abstract ( 34 )   PDF (6289KB) ( 25 )   The inert carbon-carbon (C-C) bonds cleavage is a main bottleneck in the chemical upcycling of recalcitrant polyolefin plastics waste. Here we develop an efficient strategy to catalyze the complete cleavage of C-C bonds in mixed polyolefin plastics over non-noble metal catalysts under mild conditions. The nickel-based catalyst involving Ni2Al3phase enables the direct transformation of mixed polyolefin plastics into natural gas, and the gas carbon yield reaches up to 89.6%. Reaction pathway investigation reveals that natural gas comes from the stepwise catalytic cleavage of C-C bonds in polypropylene, and the catalyst prefers catalytic cleavage of terminal C-C bond in the side-chain with the low energy barrier. Additionally, our developed approach is evaluated by the technical economic analysis for an economically competitive production process.

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Coupling ferromagnetic ordering electron transfer channels and surface reconstructed active species for spintronic electrocatalysis of water oxidation Zexing He, Xiaokang Liu, Minghui Zhang, Lei Guo, Muhammad Ajmal, Lun Pan, Chengxiang Shi, Xiangwen Zhang, Zhen-Feng Huang, Ji-Jun Zou 2023, 85(10): 570-580.  DOI: 10.1016/j.jechem.2023.06.043 Abstract ( 5 )   PDF (8553KB) ( 4 )   Sluggish reaction kinetics of oxygen evolution reaction (OER), resulting from multistep proton-coupled electron transfer and spin constriction, limits overall efficiency for most reported catalysts. Herein, using modeled ZnFe2-xNixO4 (0 ≤ x ≤ 0.4) spinel oxides, we aim to develop better OER electrocatalyst through combining the construction of ferromagnetic (FM) ordering channels and generation of highly active reconstructed species. The number of symmetry-breaking Fe-O-Ni structure links to the formation of FM ordering electron transfer channels. Meanwhile, as the number of Ni3+ increases, more ligand holes are formed, beneficial for redirecting surface reconstruction. The electro-activated ZnFe1.6Ni0.4O4 shows the highest specific activity, which is 13 and 2.5 times higher than that of ZnFe2O4 and unactivated ZnFe1.6Ni0.4O4, and even superior to the benchmark IrO2 under the overpotential of 350 mV. Applying external magnetic field can make electron spin more aligned, and the activity can be further improved to 39 times of ZnFe2O4. We propose that intriguing FM exchange-field interaction at FM/paramagnetic interfaces can penetrate FM ordering channels into reconstructed oxyhydroxide layers, thereby activating oxyhydroxide layers as spin-filter to accelerate spin-selective electron transfer. This work provides a new guideline to develop highly efficient spintronic catalysts for water oxidation and other spin-forbidden reactions.

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Water molecules and oxygen-vacancy modulation of vanadium pentoxide with fast kinetics toward ultrahigh power density and durable flexible all-solid-state zinc ion battery Wenda Qiu, Yunlei Tian, Shuting Lin, Aihua Lei, Zhangqi Geng, Kaitao Huang, Jiancong Chen, Fuchun Huang, Huajie Feng, Xihong Lu 2023, 85(10): 581-591.  DOI: 10.1016/j.jechem.2023.06.042 Abstract ( 3 )   PDF (10332KB) ( 5 )   Aqueous zinc ion battery (ZIB) with many virtues such as high safety, cost-effective, and good environmental compatibility is a large-scale energy storage technology with great application potential. Nevertheless, its application is severely hindered by the slow diffusion of zinc ions in desirable cathode materials. Herein, a technique of water-incorporation coupled with oxygen-vacancy modulation is exploited to improve the zinc ions diffusion kinetics in vanadium pentoxide (V2O5) cathode for ZIB. The incorporated water molecules replace lattice oxygen in V2O5, and function as pillars to expand interlayer distance. So the structural stability can be enhanced, and the zinc ions diffusion kinetics might also be promoted during the repeated intercalation/deintercalation. Meanwhile, the lattice water molecules can effectively enhance conductivity due to the electronic density modulation effect. Consequently, the modulated V2O5 (H-V2O5) cathode behaves with superior rate capacity and stable durability, achieving 234 mA h g-1 over 9000 cycles even at 20 A g-1. Furthermore, a flexible all-solid-state (ASS) ZIB has been constructed, exhibiting an admirable energy density of 196.6 W h kg-1 and impressive power density of 20.4 kW kg-1 as well as excellent long-term lifespan. Importantly, the assembled flexible ASS ZIB would be able to work in a large temperature span (from -20 to 70 °C). Additionally, we also uncover the energy storage mechanism of the H-V2O5 electrode, offering a novel approach for creating high-kinetics cathodes for multivalent ion storage.