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2022, Vol. 74, No. 11　Online: 15 November 2022

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Rapid and reversible Na deposition onto Al nanosheet arrays Fang Tang, Rongqing Xia, Dong Chen, Yu Yao, Lin Liu, Yuezhan Feng, Xianhong Rui, Yan Yu 2022, 74(11): 1-7.  DOI: 10.1016/j.jechem.2022.06.026 Abstract ( 17 )   PDF (5820KB) ( 10 )   Sodium metal battery (SMB) is regarded as a promising candidate for next-generation high-energy bat-tery due to high theoretical capacity and abundant natural resources. However, the growth of sodium dendrites and large volume expansion during the processes of sodium plating and stripping seriously restrict the practical application of SMBs. Here, a three-dimensional skeleton of aluminum nanosheet arrays (Al NSARs) is constructed by a facile etching approach to achieve rapid and reversible Na plat-ing/stripping. The Al NSARs with large geometric specific surface and plentiful cavities can provide rich active nucleation sites, reduce local current density and accommodate Na volume change, which lead to uniform deposition of sodium with dendrite-free morphology. As a result, Na plating/stripping on Al NSARs can stably operate over 650 cycles at 2 mA cm-2/2 mAh cm-2 with average Coulombic efficiency (CE) of 100.0% and low potential polarization of 27 mV. Moreover, the full cell of Na3V2(PO4)3|| Al NSARs@Na can run for over 1800 cycles at a high rate of 20C. These superior properties, combined with relatively low cost and weight of Al, enable our Al NSARs to be great prospect for practical applications.

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Consecutive hybrid mechanism boosting Na+ storage performance of dual-confined SnSe2 in N, Se-doping double-walled hollow carbon spheres Xiaoyu Wu, Zhenshan Yang, Lin Xu, JianHua Wang, Lele Fan, Fanjie Kong, Qiaofang Shi, Yuanzhe Piao, Guowang Diao, Ming Chen 2022, 74(11): 8-17.  DOI: 10.1016/j.jechem.2022.06.024 Abstract ( 6 )   PDF (12952KB) ( 5 )   Rationally designed hierarchical structures and heteroatomic doping of carbon are effective strategies to enhance the stability and electrical conductivity of materials. Herein, SnSe2 flakes were generated in the double-walled hollow carbon spheres (DWHCSs), in which N and Se atoms were doped in the carbon walls, to construct SnSe2@N, Se-DWHCSs by confined growth and in-situ derivatization. The N and Se-doped DWHCSs can effectively limit the size increase of SnSe2, promote ion diffusion kinetics, and buffer volume expansion, which can be proved by electron microscope observation and density functional the-ory calculation. Consequently, the SnSe2@N, Se-DWHCSs as an anode material for sodium ion batteries (SIBs) demonstrated a distinguished reversible capacity of 322.8 mAh g-1 at 5 A g-1 after 1000 cycles and a superior rate ability of 235.3 mAh g-1 at an ultrahigh rate of 15 A g-1. Furthermore, the structure evolution and electrochemical reaction processes of SnSe2@N, Se-DWHCSs in SIBs were analyzed by ex-situ methods, which confirmed the consecutive hybrid mechanism and the phase transition process.

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An asymmetric bilayer polymer-ceramic solid electrolyte for high-performance sodium metal batteries Han Wang, Yongjiang Sun, Qing Liu, Zhiyuan Mei, Li Yang, Lingyan Duan, Hong Guo 2022, 74(11): 18-25.  DOI: 10.1016/j.jechem.2022.07.010 Abstract ( 10 )   PDF (6204KB) ( 8 )   Manufacturing an excellent solid electrolyte compatible with a high-voltage cathode is viewed as a crit-ical tactic for improving the energy density of solid-state sodium-ion batteries (SSIBs). A novel asymmet-ric bilayer solid electrolyte of the PEO-SN-NaClO4|NZSP-NSO with an anti-reduction PEO-SN-NaClO4 layer close to the Na side is constructed by solution casting. The ionic conductivity is enhanced by using suc-cinonitrile (SN) in polyethylene oxide (PEO) polymer electrolyte. The anti-oxidation layer of Na3Zr2Si2PO12 with Na2SiO3 (NZSP-NSO) is served as the support of the membrane on the cathode, which could improve the interface compatibility and electrochemical performance of SSIBs. The asymmetric bilayer solid electrolyte simultaneously features a wide electrochemical stability window (4.65 V vs. Na+/Na) and a high conductivity (2.68 × 10-4 S cm-1). Furthermore, the solid electrolyte demonstrates stable Na plating/stripping over 700 h and remarkably improves cycling stability in Na/Na3V2(PO4)3 bat-teries with an ultra-high capacity retention of 99.6% after 100 cycles at 50 °C and 0.5 C. This study pro-vides an effective strategy for designing asymmetric high sodium ion conductivity solid-state electrolytes for high-performance SSIBs.

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Effect of specifically-adsorbed polysulfides on the electron transfer kinetics of sodium metal anodes Huazhao Yang, Yu Li, Xianxian Zhou, Xiaotao Ma, Donghong Duan, Shibin Liu 2022, 74(11): 26-33.  DOI: 10.1016/j.jechem.2022.07.008 Abstract ( 5 )   PDF (4320KB) ( 3 )   Room-temperature sodium-sulfur (RT Na-S) batteries hold great promise for large-scale energy storage applications owing to the high energy density and earth-abundance of Na and S. However, the dissolution and migration of sodium polysulfides, uncontrollable Na dendrite growth, and the lack of studies on Na electrodeposition kinetics have hindered the development of these batteries. Herein, we reveal the mech-anism of sodium polysulfides on the Na plating/stripping kinetics using a three-electrode system. First, the kinetic behavior deviates from the commonly supposed Butler-Volmer model, which is well described by the Marcus model. In addition, the specific adsorption of polysulfides on the sodium elec-trode surface is a key factor influencing the kinetics. Higher-order polysulfides ($S_{8}^{2-}$ and $S_{6}^{2-}$) exhibit distinct specific adsorption behaviors because of their high adsorption energies compared to lower-order polysulfides ($S_{4}^{2-}$ and $S_{2}^{2-}$). The electrostatic effect caused by specific adsorption can accelerate the kinetics, whereas the blocking effect can slow the kinetics. Thus, this competitive relationship enables low concentrations of high-order polysulfides to stimulate kinetics. This implies that a weak shuttle effect is beneficial for obtaining a stable Na deposition in RT Na-S batteries. An in-depth understanding of the Na electrodeposition kinetics provides beneficial clues for future metal sodium/electrolyte interface designs.

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Understanding the mechanism of capacity increase during early cycling of commercial NMC/graphite lithium-ion batteries Jia Guo, Yaqi Li, Jinhao Meng, Kjeld Pedersen, Leonid Gurevich, Daniel-Ioan Stroe 2022, 74(11): 34-44.  DOI: 10.1016/j.jechem.2022.07.005 Abstract ( 44 )   PDF (10842KB) ( 49 )   A capacity increase is often observed in the early stage of Li-ion battery cycling. This study explores the phenomena involved in the capacity increase from the full cell, electrodes, and materials perspective through a combination of non-destructive diagnostic methods in a full cell and post-mortem analysis in a coin cell. The results show an increase of 1% initial capacity for the battery aged at 100% depth of discharge (DOD) and 45 °C. Furthermore, large DODs or high temperatures accelerate the capacity increase. From the incremental capacity and differential voltage (IC-DV) analysis, we concluded that the increased capacity in a full cell originates from the graphite anode. Furthermore, graphite/Li coin cells show an increased capacity for larger DODs and a decreased capacity for lower DODs, thus in agreement with the full cell results. Post-mortem analysis results show that a larger DOD enlarges the graphite d-space and separates the graphite layer structure, facilitating the Li+ diffusion, hence increasing the battery capacity.

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Molybdenum disulfide (MoS2)-based electrocatalysts for hydrogen evolution reaction: From mechanism to manipulation Yao Xu, Riyue Ge, Jack Yang, Jiancheng Li, Sean Li, Ying Li, Jiujun Zhang, Jing Feng, Bin Liu, Wenxian Li 2022, 74(11): 45-71.  DOI: 10.1016/j.jechem.2022.06.031 Abstract ( 17 )   PDF (34522KB) ( 17 )   Molybdenum disulfide (MoS2)-based materials as the non-noble metal catalysts have displayed the potential capability to drive electrocatalytic hydrogen evolution reaction (HER) for green hydrogen pro-duction along with their intrinsic activity, tunable electronic properties, low cost, and abundance reserves, which have attracted intensive attention as alternatives to the low-abundance and high-cost platinum-based catalysts. However, their insufficient catalytic HER activities and stability are the major challenges for them to become practically applicable. Hereby, the MoS2-based electrocatalysts for HER are comprehensively reviewed to explain the fundamental science behind the manipulations of the crys-tal structure, microstructure, surface, and interface of MoS2 in order to enhance its catalytic performance through changing the electrical conductivity, the number of active sites, surface wettability, and the Gibbs free energy for hydrogen adsorption (DGH). Recent studies in surface/interface engineering, such as phase engineering, defect engineering, morphology design, and heterostructure construction, are ana-lyzed to reveal the state-of-the-art strategies for designing and preparing the cost-effective and high-performance MoS2-based catalysts through optimizing the charge transfer, surface-active sites, DGH, and surface hydrophilicity. Lastly, the perspectives, challenges, and future research directions of HER electrocatalysis are also given to facilitate the further research and development of HER catalysts.

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Low-strain binary hexacyanoferrate nanocuboids with concentration-gradient structure towards fast and durable energy storage Yutong Lin, Bing Han, Donglan Zhang, Xueya Liu, Zili Wang, Zhengyu Wang, Liang Si, Sen Zhang, Chao Deng 2022, 74(11): 72-84.  DOI: 10.1016/j.jechem.2022.07.002 Abstract ( 8 )   PDF (12001KB) ( 5 )   The exploration of low-strain and high-performance electrode is a crucial issue for aqueous potassium-ion battery (AKIB). Herein, a novel potassium mediated iron/manganese binary hexacyanoferrate nano-cuboid, i.e., KxFeyMn1-y[Fe(CN)6]·nH2O (KFeMnHCF) nanocuboid, with the concentration-gradient (CG) structure is designed as a high-performance cathode for AKIB. Internal the CG-KFeMnHCF nanocuboids, the manganese content gradually decreases from the interior to the surface and the iron content changes reverse, resulting in the concentration-gradient structure. Both experimental and finite element simula-tion (FEA) results demonstrate the lower internal stress and better mechanical characteristics of CG struc-tured nanocuboid than the homogenous structured one upon ion intercalation/deintercalation processes. Meanwhile, the electrochemical testing and theoretical calculation (DFT) results disclose the substitution of Fe to Mn in the KMnHCF crystal results in the enhanced electronic conductivity, potassium migration and electrochemical kinetics. Taken both advantages from the well-designed architecture and optimized crystal structure, the CG-KFeMnHCF achieves the superior rate capability and ultrahigh stability in aque-ous potassium ion system. In particular, the CG-KFe0.31Mn0.69HCF achieves the best comprehensive prop-erties among all the samples. The full AKIBs based on CG-KFe0.31Mn0.69HCF cathode achieves the high energy density (83 Wh kg-1), superior power density, high capacity retention (83%) over high-rate long-term cycles, good adaptation to a wide temperature range (-20 to 40 °C) and high reliability even under outside deformations. Therefore, this work not only provides a new clue to design the high-performance cathode, but also promotes the applications of AKIBs for diverse electronics and wide work-ing environments.

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Understanding the surface segregation behavior of bimetallic CoCu toward HMF oxidation reaction Yanwei Zhu, Jianqiao Shi, Yingying Li, Yuxuan Lu, Bo Zhou, Shuangyin Wang, Yuqin Zou 2022, 74(11): 85-90.  DOI: 10.1016/j.jechem.2022.05.041 Abstract ( 8 )   PDF (5414KB) ( 2 )   Surface segregation is ubiquitous in multi-component materials and is of great important for catalysis but little is known on the surface structure under graphene encapsulation. Here, we show that the graphene encapsulated CoCu performs well for the electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) with the onset potential before 1.23 VRHE and a nearly 100% selectivity of FDCA under 1.4 VRHE. From the experimental results, the unprecedented catalytic performance was attributed to local structural distortion and sub-nanometer lattice composition of the CoCu surface. We accurately show the dispersed Cu doped Co3O4 nano-islands with a lot of edge sites on the bimetallic Co-Cu surface. While, the gradient components effectively facilitate the establishment of built-in electric field and accelerate the charge transfer. Theoretical and experimental results reveal that the surface Co and neighbouring Cu atoms in sub-nanometer lattice synergistically promote the catalysis of HMF. This work offers new insights into surface segregation in tuning the element spatial distribution for catalysis.

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Double-layer solid-state electrolyte enables compatible interfaces for high-performance lithium metal batteries Xiao Chen, Qiushi Sun, Jian Xie, Cheng Huang, Xiongwen Xu, Jian Tu, Xinbing Zhao, Tiejun Zhu 2022, 74(11): 91-99.  DOI: 10.1016/j.jechem.2022.07.006 Abstract ( 10 )   PDF (7516KB) ( 2 )   Solid-state lithium metal batteries are promising next-generation batteries for both micro-scale inte-grated electronic devices and macro-scale electric vehicles. However, electrochemical incompatibility between electrolyte and electrodes causes continuous performance degradation. Here, we report a unique design of a double-layer composite solid-state electrolyte (D-CSE), where each layer, composed of both polymer and ceramics, is electrochemically compatible with its contacting electrode (Li anode or LiCoO2 cathode). The D-CSE has a small thickness (50 lm), high thermal stability (up to 160 °C without noticeable deformation), and good flexibility even at a high ceramics content (66.7 wt%). Large-area self-standing film can be obtained by a facile coating route. The electrolyte/electrode interface can be further enhanced via forming a soft interface by in-situ polymerization. Quasi-solid-state Li|D-CSE|LiCoO2 coin cells with the cathode-supported D-CSE can deliver a high initial discharge capacity of 134 mAh g-1 and a high capacity retention of 83% after 200 cycles at 0.5 C and 60 °C. Quasi-solid-state Li|D-CSE| LiCoO2 pouch cells (designed capacity 8.6 mAh) with the self-standing D-CSE have a high retention of 80% after 180 cycles at 2 mA charge and 4 mA discharge. At a high cathode loading (19.1 mg cm-2), the Li|D-CSE|LiCoO2 pouch cell still can be stably cycled, and can withstand abuse tests of folding, cutting and nail penetration, indicating practical applications of the D-CSE.

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Boosting of reversible capacity delivered at a low voltage below 0.5 V in mildly expanded graphitized needle coke anode for a high-energy lithium ion battery Dong Sun, Lu Zhao, Zhihua Xiao, Kai Zhao, Rundan Lin, Hongmei Song, Xilu Zhang, Xinlong Ma, Chong Peng, Xiaoqiao Huang, Xingxun Li, Jinsen Gao, Chunming Xu 2022, 74(11): 100-110.  DOI: 10.1016/j.jechem.2022.07.013 Abstract ( 6 )   PDF (9338KB) ( 2 )   The rate performance and cycle stability of graphitized needle coke (GNC) as anode are still limited by the sluggish kinetics and volume expansion during the Li ions intercalation and de-intercalation process. Especially, the output of energy density for lithium ion batteries (LIBs) is directly affected by the delithi-ation capacity below 0.5 V. Here, the mildly expanded graphitized needle coke (MEGNC) with the enlarged interlayer spacing from 0.346 to 0.352 nm is obtained by the two-step mild oxidation interca-lation modification. The voltage plateau of MEGNC anode below 0.5 V is obviously broadened as com-pared to the initial GNC anode, contributing to the enhancement of Li storage below the low voltage plateau. Moreover, the coin full cell and pouch full cell configured with MEGNC anode exhibit much enhanced Li storage ability, energy density and better cycling stability than those full cells configured with GNC and commercial graphite anodes, demonstrating the practical application value of MEGNC. The superior anode behaviors of MEGNC including the increased effective capacity at low voltage and superior cyclic stability are mainly benefited from the enlarged interlayer spacing, which not only accel-erates the Li ions diffusion rate, but also effectively alleviates the volume expansion and fragmentation during the Li ions intercalation process. In addition, the above result is further confirmed by the density functional theory simulation. This work provides an effective modification strategy for the NC-based gra-phite to enhance the delithiation capacity at a low voltage plateau, dedicated to improving the energy density and durability of LIBs.

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Insight into the boosted activity of TiO2-CoP composites for hydrogen evolution reaction: Accelerated mass transfer, optimized interfacial water, and promoted intrinsic activity Mingming Deng, Hongmei Yang, Lishan Peng, Ling Zhang, Lianqiao Tan, Guiju He, Minhua Shao, Li Li, Zidong Wei 2022, 74(11): 111-120.  DOI: 10.1016/j.jechem.2022.06.047 Abstract ( 8 )   PDF (10318KB) ( 1 )   The use of abundant elements in the earth as electrocatalytic hydrogen production catalysts is of great significance for hydrogen energy cycling. Herein, we report amorphous TiO2-decorated CoP/NF (TiO2-CoP/NF) as an excellent electrocatalyst for alkaline hydrogen evolution reaction (HER). The well-dispersed amorphous TiO2 on nanoneedle-like CoP arrays preserves the crystal structure of CoP and changes its electronic structure by interfacial charge transfer. Compared to CoP/NF catalyst, the TiO2-CoP/NF composite catalyst exhibits high HER activity with an overpotential of 61 mV at 10 mA cm-2 and high stability. Importantly, it almost maintains the Volmer step as a rate-determining step (RDS) and the Tafel slope at a wide cathodic potential range showing the fast kinetics under large polarization regions. Theoretical simulations reveal that the combination of TiO2 and CoP selectively accelerates the hydrated K+ diffusion, regulates the interfacial water orientation to adapt to the subsequent smooth water dissociation, and optimizes *H adsorption/H2 desorption. The strengthened coupling of HER multi-scale-processes on transition metal compound composites catalysts is the underlying mechanism for improving HER activity.

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Nanoconfinement effect of nanoporous carbon electrodes for ionic liquid-based aluminum metal anode Juhee Yoon, Seongbak Moon, Son Ha, Hyung-Kyu Lim, Hyoung-Joon Jin, Young Soo Yun 2022, 74(11): 121-127.  DOI: 10.1016/j.jechem.2022.06.048 Abstract ( 5 )   PDF (5602KB) ( 2 )   Rechargeable aluminum batteries (RABs), which use earth-abundant and high-volumetric-capacity metal anodes (8040 mAh cm-3), have great potential as next-generation power sources because they use cheaper resources to deliver higher energies, compared to current lithium ion batteries. However, the mechanism of charge delivery in the newly developed, ionic liquid-based electrolytic system for RABs dif-fers from that in conventional organic electrolytes. Thus, targeted research efforts are required to address the large overpotentials and cycling decay encountered in the ionic liquid-based electrolytic system. In this study, a nanoporous carbon (NPC) electrode with well-developed nanopores is used to develop a high-performance aluminum anode. The negatively charged nanopores can provide quenched dynamics of electrolyte molecules in the aluminum deposition process, resulting in an increased collision rate. The fast chemical equilibrium of anionic species induced by the facilitated anionic collisions leads to more favorable reduction reactions that form aluminum metals. The nanoconfinement effect causes separated nucleation and growth of aluminum nanoparticles in the multiple confined nanopores, leading to higher coulombic efficiencies and more stable cycling performance compared with macroporous carbon black and 2D stainless steel electrodes.

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Flexible PVA/BMIMOTf/LLZTO composite electrolyte with liquid-comparable ionic conductivity for solid-state lithium metal battery Hyesun Jeon, Hai Anh Hoang, Dukjoon Kim 2022, 74(11): 128-139.  DOI: 10.1016/j.jechem.2022.07.014 Abstract ( 13 )   PDF (10613KB) ( 7 )   Poly(vinyl alcohol) (PVA)/1-butyl-3-methylimidazolium trifluoromethanesulfonate (BMIMOTf)/ Li6.4La3Zr1.4Ta0.6O12 (LLZTO) solid-state composite electrolyte (SSCE) membranes were synthesized for solid-state lithium metal battery application. The garnet-type LLZTO nanoparticles were surface-coated with the polydopamine layer of 8-10 nm thickness to enhance the dispersion status of LLZTO particles in the PVA matrix. The hydrophilic BMIMOTf ionic liquid (IL) was added along with LLZTO nanoparticles to enhance the ionic conductivity and electrochemical stability of the SSCE membranes. The synthesized composite electrolyte membrane containing 7 wt% of LLZTO and 60 wt% of BMIMOTf showed the out-standing Li+ conductivity of 2 × 10-3 S cm-1 and the lithium transference number of 0.76 at room tem-perature in the firm and flexible solid state with the tensile strength of 8 MPa. Such a high single ion conduction characteristic led to the quite low interfacial resistance of 39 X between the composite elec-trolyte and the lithium anode. Owing to these superior properties of composite membranes, the LiFePO4| SSCE|Li cell exhibited an excellent discharge capacity of 165 mAh g-1 at 0.2 C, maintaining the coulombic efficiency of 98% after 100 cycles at room temperature.

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Promoting surface reconstruction of NiFe layered double hydroxides via intercalating [Cr(C2O4)3]3— for enhanced oxygen evolution Yujie Wu, Minglei Song, Yu-Cheng Huang, Chung-Li Dong, Yingying Li, Yuxuan Lu, Bo Zhou, Dongdong Wang, Jianfeng Jia, Shuangyin Wang, Yanyong Wang 2022, 74(11): 140-148.  DOI: 10.1016/j.jechem.2022.06.045 Abstract ( 5 )   PDF (9329KB) ( 4 )   Rationally manipulating surface reconstruction of catalysts for water oxidation, inducing formation and dynamic accumulation of catalytically active centers still face numerous challenges. Herein, the introduc-tion of [Cr(C2O4)3]3- into NiFe LDHs by intercalation engineering to promote surface reconstruction achieves an advanced oxygen evolution reaction (OER) activity. In view of the weak electronegativity of Cr3+ in [Cr(C2O4)3]3-, the intercalation of [Cr(C2O4)3]3- is expected to result in an electron-rich struc-ture of Fe sites in NiFe LDHs, and higher valence state of Ni can be formed with the charge transfer between Fe and Ni. The optimized electronic structure of NiFe-[Cr(C2O4)3]3--LDHs with more active Ni3+ species and the expedited dynamic generation of Ni3+(Fe)OOH phase during the OER process con-tributed to its excellent catalytic property, revealed by in situ X-ray absorption spectroscopy, Raman spectroscopy, and quasi-in situ X-ray photoelectron spectroscopy. With the modulated electronic struc-ture of metal sites, NiFe-[Cr(C2O4)3]3--LDHs exhibited promoted OER property with a lower overpotential of 236 mV at the current density of 10 mA cm-2. This work illustrates the intercalation of conjugated anion to dynamically construct desired Ni3+ sites with the optimal electronic environment for improved OER electrocatalysis.

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Trimetallic synergistic optimization of 0D NiCoFe-P QDs anchoring on 2D porous carbon for efficient electrocatalysis and high-energy supercapacitor Ruiqi Liu, Xue-Rong Shi, Yi Wen, Xiaoxuan Shao, Chen Su, Jing Hu, Shusheng Xu 2022, 74(11): 149-158.  DOI: 10.1016/j.jechem.2022.07.015 Abstract ( 10 )   PDF (8784KB) ( 4 )   Developing multi-functional and low-cost noble-metal-free catalysts such as transition metal phosphides (TMPs) to replace noble-metal is of practical significance for energy conversion and storage. However, the low-durability and the agglomeration phenomenon during the electrochemical process limit their prac-tical applications. Herein, using metal-organic frameworks (MOFs) as the precursor and a combined strategy of gradient temperature calcination and thermal phosphorization, a 0D/2D heterostructure of NiCoFe-P quantum dots (QDs) anchored on porous carbon was successfully developed as highly efficient electrode materials for overall water splitting and supercapacitors. Owing to this distinctive 0D/2D heterostructure and the synergistic effect of multi-metallic TMPs, the NiCoFe-P/C exhibits excellent elec-trocatalytic activity and durability of HER (87 mV at 10 mA cm-2) and OER (257 mV at 100 mA cm-2) in the KOH electrolyte. When NiCoFe-P/C is used as the two electrodes of electrolyzed water, only 1.55 V can drive the current density to 10 mA cm-2. At the same time, our NiCoFe-P/C possessed extraordinary prop-erty for charge storage. In particular, an ultra-high energy density of 100.8 Wh kg-1 was achieved at a power density of 900.0 W kg-1 for our assembled hybrid supercapacitor device NiCoFe-P/C (2:1)//acti-vated carbon (AC). This work may open a potential way for the design of 0D/2D hybrid multi-functional nanomaterials based on TMPs QDs.

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A review of deep learning approach to predicting the state of health and state of charge of lithium-ion batteries Kai Luo, Xiang Chen, Huiru Zheng, Zhicong Shi 2022, 74(11): 159-173.  DOI: 10.1016/j.jechem.2022.06.049 Abstract ( 41 )   PDF (6217KB) ( 30 )   In the field of energy storage, it is very important to predict the state of charge and the state of health of lithium-ion batteries. In this paper, we review the current widely used equivalent circuit and electro-chemical models for battery state predictions. The review demonstrates that machine learning and deep learning approaches can be used to construct fast and accurate data-driven models for the prediction of battery performance. The details, advantages, and limitations of these approaches are presented, com-pared, and summarized. Finally, future key challenges and opportunities are discussed.

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Anthraquinone derivatives supported by Ti3C2(MXene) as cathode materials for aluminum-organic batteries Gaohong Wu, Cuncai Lv, Wenrong Lv, Xiaoxiao Li, Wenming Zhang, Zhanyu Li 2022, 74(11): 174-183.  DOI: 10.1016/j.jechem.2022.07.016 Abstract ( 7 )   PDF (8761KB) ( 2 )   Due to the advantages of aluminum in abundance in the earth's crust and safety, how to exploit these advantages to develop high-performance rechargeable aluminum batteries to replace traditional batter-ies has become an urgent issue. The key to solving this problem is to find suitable materials as cathode for aluminum batteries. Here, we propose a strategy in which Ti3C2(MXene) is used as a loaded structure for the organic anthraquinone derivative Benzo[1,2-b:4,5-b']dithiophene-4,8-dione (BDTO). This strategy enables the self-stacking of monolayer MXene into a layered structure while embedding organics into it. The unique structure enables efficient and reversible intercalation/deintercalation of Al3+. At the same time, it exhibits excellent electrochemical performance, and its reversible capacity reaches 229.8 mAh g-1. Moreover, it can still maintain a capacity of 134.9 mAh g-1 after 500 cycles. In addition, compared with BDTO, the rate performance of MXene@BDTO has also been greatly improved. Meanwhile, this unique layered structure also brings better electronic conductivity and ionic diffusion coefficient. We also demonstrate that the battery mechanism is a reaction between three C@O and one Al3+ through mul-tiple characterization methods and density functional calculations (DFT). The advantages of MXene@BDTO provide a better research basis for the study of rechargeable Aluminum-Organic batteries, and provide a good idea to explore the development of Aluminum-Organic batteries.

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A universal design for triggering the precise micro-structure reconstruction through in-situ electro-regulating to boost the pseudocapacitance of MnO2 Lijin Yan, Jiangyu Hao, Baibai Liu, Xuefeng Zou, Qibin Wu, Jin Hou, Jizhou Duan, Shicheng Wei, Yang Zhou, Bin Xiang, Baorong Hou 2022, 74(11): 184-197.  DOI: 10.1016/j.jechem.2022.07.012 Abstract ( 5 )   PDF (15180KB) ( 2 )   Developing a precise controllable strategy for modulating the micro-morphology, atom coordination environment, and electronic structure of electrode materials is crucial for the performance in the field of energy storage, yet still a tremendous challenge. Herein, a facile and universal in-situ electrochemical self-optimization design, electro-regulating, is designed to controllably produce electrode materials with abundant defects. Through detailed characterization studies, the microstructure of MnO2 is reconstructed after electro-regulating, which exhibits a structure of small fragments with numerous holes due to the partial self-dissolution of acidic oxides under an alkaline operating environment. Furthermore, the electro-regulating strategy not only presents the formation steps of numerous holes but is also accompa-nies by a number of O vacancies generation process due to the activation of an external electric field. This study provides a new inspiration for reasonably designing advanced functional electrode materials for various electrochemical applications and beyond.

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Mechanically induced Cu active sites for selective C-C coupling in CO2 electroreduction Zhao Chen, Yao Song, Zhenyu Zhang, Yafeng Cai, Huan Liu, Wenxiang Xie, Dehui Deng 2022, 74(11): 198-202.  DOI: 10.1016/j.jechem.2022.07.011 Abstract ( 7 )   PDF (3038KB) ( 4 )   Developing a convenient method to endow bulk Cu-based electrode with high activity of electrocatalytic CO2 reduction reaction (CO2RR) to multicarbon (C2+) products is desirable but challenging. Herein, for the first time, we report that mechanical polishing induces highly reactive Cu sites for selective C-C coupling in CO2RR. We find that mechanical polishing could endow Cu foil with abundant nanocavity surface structure, which efficiently confines the carbonaceous intermediates to enhance the probability of C-C coupling reaction. By confining the carbonaceous intermediates with Cu nanocavity, the as-prepared electrode delivers a Faradaic efficiency toward C2+ products of 65.7% at -1.3 V vs. RHE, which is enhanced up to 1.7 folds compared with that of commercial Cu foil. This work provides a new method to enable Cu foil with high activity of CO2RR to C2+ products.

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A novel structure of quasi-monolayered NiCo-bimetal-phosphide for superior electrochemical performance Long Zhao, Ming Wen, Yakun Tian, Qingsheng Wu, Yongqing Fu 2022, 74(11): 203-211.  DOI: 10.1016/j.jechem.2022.07.017 Abstract ( 7 )   PDF (7294KB) ( 12 )   Bimetallic transition metal phosphides (TMPs) as potential candidates for superior electrochemical per-formance are still facing great challenges in the controllable preparation of two-dimensional (2D) struc-tures with high aspect ratio. Herein, a novel structure of quasi-monolayered NiCo-bimetal-phosphide (NiCoP) has been designed and successfully synthesized by the newly developed process combined with ultrasonic-cavitation and phase-transition. This is the first time to break through the controllable prepa-ration of 2D bimetal-phosphides with a thickness of 0.98 nm in sub-nanoscale. Based on the advantages of 2D quasi-monolayer structure with dense crystalline-amorphous interface and the reconfigured elec-tronic structure between Nid+/Cod+ and Pd-, the optimized Ni5%CoP exhibits an outstanding bifunctional performance for electrocatalyzing both hydrogen evolution reaction and oxygen evolution reaction in an alkaline medium. Ni5%CoP presents lower overpotentials and voltage of 84 mV & 259 mV and 1.48 V at the current density of 10 mA cm-2 for HER & OER and overall water splitting, respectively, which are superior to most other reported 2D bimetal-phosphides. This work provides a new strategy to optimize the performance of electrolytic water for bimetal-phosphates and it may be of significant value in extending the design of other ultrathin 2D structured catalysts.

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Molten salt electrochemical modulation of Ni/Co nanoparticles onto N-doped carbon for oxygen reduction Xinxin Liang, Jialin Chen, Biao Hong, Tingting Wan, Wei Weng, Wei Xiao 2022, 74(11): 212-217.  DOI: 10.1016/j.jechem.2022.06.044 Abstract ( 4 )   PDF (4163KB) ( 2 )   Activation of oxygen over non-precious materials has been an imperative task to develop efficient elec-trochemical energy storage and conversion such as fuel cells and metal-air batteries. Herein, a molten salt electrochemical modulation of metal-nitrogen-carbon based compounds (M-N-C) is achieved. By elec-trochemical treatment of polydopamine-coated NiCo2O4 (NiCo2O4@PDA) in molten Li2CO3-Na2CO3-K2CO3 at 500 °C, Ni/Co bimetal-nitrogen-carbon catalyst (denoted as Ni/Co@NC) consisting of Ni-Co nanoparticles anchoring on porous nitrogen-doped carbon is constructed and evaluated as electrocata-lysts towards the oxygen reduction reaction (ORR). Experimental and calculation results confirm that alloying of Ni-Co and nitrogen doping to carbon enhances the rate-determining transformation of *OH intermediate during ORR. The Ni/Co@NC hence shows an ORR activity comparable with the commercial Pt/C.

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Application-oriented hydrolysis reaction system of solid-state hydrogen storage materials for high energy density target: A review Jing Yao, Zhen Wu, Huan Wang, Fusheng Yang, Jianwei Ren, Zaoxiao Zhang 2022, 74(11): 218-238.  DOI: 10.1016/j.jechem.2022.07.009 Abstract ( 4 )   PDF (14343KB) ( 5 )   Hydrogen storage and delivery technology is still a bottleneck in the hydrogen industry chain. Among all kinds of hydrogen storage methods, light-weight solid-state hydrogen storage (LSHS) materials could become promising due to its intrinsic high hydrogen capacity. Hydrolysis reaction of LSHS materials occurs at moderate conditions, indicating the potential for portable applications. At present, most of review work focuses on the improvement of material performance, especially the catalysts design. This part is important, but the others, such as operation modes, are also vital to to make full use of material potential in the practical applications. Different operation modes of hydrolysis reaction have an impact on hydrogen capacity to various degrees. For example, hydrolysis in solution would decrease the hydro-gen capacity of hydrogen generator to a low value due to the excessive water participating in the reac-tion. Therefore, application-oriented operation modes could become a key problem for hydrolysis reaction of LSHS materials. In this paper, the operation modes of hydrolysis reaction and their practical applications are mainly reviewed. The implements of each operation mode are discussed and compared in detail to determine the suitable one for practical applications with the requirement of high energy den-sity. The current challenges and future directions are also discussed.

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Monodisperse polar NiCo2O4 nanoparticles decorated porous graphene aerogel for high-performance lithium sulfur battery Xiaohui Tian, Yingke Zhou, Bingyin Zhang, Naomie Beolle Songwe Selabi, Guiru Wang 2022, 74(11): 239-251.  DOI: 10.1016/j.jechem.2022.07.021 Abstract ( 2 )   PDF (5843KB) ( 2 )   Lithium sulfur battery (LSB) is a promising energy storage system to meet the increasing energy demands for electric vehicles and smart grid, while its wide commercialization is severely inhibited by the ‘‘shuttle effect” of polysulfides, low utilization of sulfur cathode, and safety of lithium anode. To overcome these issues, herein, monodisperse polar NiCo2O4 nanoparticles decorated porous gra-phene aerogel composite (NCO-GA) is proposed. The aerogel composite demonstrates high conductiv-ity, hierarchical porous structure, high chemisorption capacity and excellent electrocatalytic ability, which effectively inhibits the ‘‘shuttle effect”, promotes the ion/electron transport and increases the reaction kinetics. The NCO-GA/S cathode exhibits high discharge specific capacity (1214.1 mAh g-1 at 0.1 C), outstanding rate capability (435.7 mAh g-1 at 5 C) and remarkable cycle stability (decay of 0.031%/cycle over 1000 cycles). Quantitative analyses show that the physical adsorption provided by GA mainly contributes to the capacity of NCO-GA/S at low rate, while the chemical adsorption pro-vided by polar NiCo2O4 contributes mainly to the capacity of NCO-GA/S with the increase of current density and cycling. This work provides a new strategy for the design of GA-based composite with synergistic adsorption and electrocatalytic activity for the potential applications in LSB and related energy fields.

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A review on the current research on microwave processing techniques applied to graphene-based supercapacitor electrodes: An emerging approach beyond conventional heating Rajesh Kumar, Sumanta Sahoo, Ednan Joanni, Rajesh Kumar Singh 2022, 74(11): 252-282.  DOI: 10.1016/j.jechem.2022.06.051 Abstract ( 3 )   PDF (29856KB) ( 1 )   The various methods for microwave processing of materials exhibit numerous advantages, such as short processing times, high yield, expanded reaction conditions, high reproducibility, and high purity of prod-ucts. Microwave-assisted synthesis strategies have been widely adopted for the preparation of high-performance graphene-based materials for supercapacitor electrodes. Metal oxides, mixed metal oxides, metal hydroxides, layered double hydroxides, carbon nanotubes and conducting polymers are some of the main materials which have been added to graphene derivatives for advanced composite/hybrid elec-trodes. This review article first provides a brief introduction and an overview of microwave heating and its advantages for processing graphene-based electrode materials. After that, a systematic survey of recently published research on microwave irradiation-assisted processing is presented, focusing on: (i) transformation of graphite/ graphite oxide into graphene/graphene oxide by exfoliation and reduction; (i i)formation of graphene derivatives in various liquid and gaseous media; (iii) modification of graphene derivatives with various metal oxides/hydroxides, carbon nanotubes, and conducting polymers for use in supercapacitors. Major challenges and future perspectives for microwave-assisted processing of graphene-based materials for cutting-edge supercapacitor electrode applications are also summarized in the conclusion.

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Progress and perspective of high-voltage lithium cobalt oxide in lithium-ion batteries Qian Wu, Bing Zhang, Yingying Lu 2022, 74(11): 283-308.  DOI: 10.1016/j.jechem.2022.07.007 Abstract ( 5 )   PDF (23934KB) ( 4 )   Lithium cobalt oxide (LiCoO2, LCO) dominates in 3C (computer, communication, and consumer) electronics-based batteries with the merits of extraordinary volumetric and gravimetric energy density, high-voltage plateau, and facile synthesis. Currently, the demand for lightweight and longer standby smart portable electronic products drives the development of the upper cut-off voltage of LCO-based bat-teries to further improve the energy density. However, several challenges, including irreversible struc-tural transformation, surface degradation, cobalt dissolution and oxygen evolution along with detrimental side reactions with the electrolyte remain with charging to a high cut-off voltage (>4.2 V vs. Li/Li+), resulting in rapid capacity decay and safety issues. Based on the degradation mechanisms and latest advances of the high-voltage LCO, this review summarizes modification strategies in view of the LCO structure, artificial interface design and electrolytes optimization. Meanwhile, many advanced characterization and monitoring techniques utilized to clarify the structural and interfacial evolution of LCO during charge/discharge process are critically emphasized. Moreover, the perspectives in terms of integrating multiple modification strategies, applying gel and solid-state electrolytes, optimizing the recovery process and scalable production are presented.

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A facile path from fast synthesis of Li-argyrodite conductor to dry forming ultrathin electrolyte membrane for high-energy-density all-solid-state lithium batteries Zhao Jiang, Hongling Peng, Jingru Li, Yu Liu, Yu Zhong, Changdong Gu, Xiuli Wang, Xinhui Xia, Jiangping Tu 2022, 74(11): 309-316.  DOI: 10.1016/j.jechem.2022.07.029 Abstract ( 14 )   PDF (8176KB) ( 6 )   All-solid-state lithium batteries (ASSLBs), utilizing sulfide solid electrolyte, are considered as the promis-ing design on account of their superior safety and high energy density, whereas the time-consuming preparation process of sulfide electrolyte powders and the thickness of electrolyte layer hinder their practical application. Herein, an innovative ultimate-energy mechanical alloying plus rapid thermal pro-cessing approach is employed to rapidly synthesize the crystalline Argyrodite-type conductor Li5.3PS4.3ClBr0.7 (LPSClBr) with superior ionic conductivity (11.7 mS cm-1). Furthermore, to realize the higher energy density of the battery, an ultrathin LPSClBr sulfide electrolyte membrane with superior ionic conductivity of 6.5 mS cm-1 is fabricated with the aid of polytetrafluoroethylene (PTFE) binder and the reinforced cellulose mesh. Moreover, a simple solid electrolyte interphase (SEI) is constructed on the surface of lithium metal to enhance anodic stability. Benefiting from the joint efforts of these mer-its, the modified ASSLBs with a high cell-level energy density of 311 Wh kg-1 show an excellent cyclic stability. The assembled all-solid-state Li2S/Li pouch cell can operate even under the severe conditions of bending and cutting, demonstrating the enormous potential of the sulfide electrolyte membrane for ASSLBs application.

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Modulating eg orbitals through ligand engineering to boost the electrocatalytic activity of NiSe for advanced lithium-sulfur batteries Tianran Yan, Jie Feng, Pan Zeng, Gang Zhao, Lei Wang, Cheng Yuan, Chen Cheng, Youyong Li, Liang Zhang 2022, 74(11): 317-323.  DOI: 10.1016/j.jechem.2022.07.025 Abstract ( 3 )   PDF (4059KB) ( 2 )   Accelerating the sluggish redox kinetics of lithium polysulfides (LiPSs) by electrocatalysis is essential to achieve high performance lithium-sulfur (Li-S) batteries. However, the issue of insufficient catalytic activity remains to be addressed. Herein, a strategy of modulating eg orbitals through ligand engineering has been proposed to boost the catalytic activity of NiSe for rapid LiPSs redox conversion. The X-ray spec-troscopic measurements and theoretical calculations reveal that partial substitution of Se with N disrupts the octahedral coordination of Ni atoms in NiSe, leading to the reduced degeneracy and upward shift of eg orbitals of Ni 3d states. As a consequence, the bonding strength of N-substituted NiSe (N-NiSe) with LiPSs is enhanced, which facilitates the interfacial charge transfer kinetics and accelerates the LiPSs redox kinetics. Therefore, the Li-S batteries assembled with N-NiSe present a high capacity of 682.6 mAh g-1 at a high rate of 5 C and a high areal capacity of 6.5 mAh cm-2 at a high sulfur loading of 6 mg cm-2. This work provides a promising strategy to develop efficient transition-metal based electrocatalysts for Li-S batteries through eg orbital modulation.

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Selective superoxide radical generation for glucose photoreforming into arabinose Jiu Wang, Heng Zhao, Peng Liu, Nael Yasri, Na Zhong, Md Golam Kibria, Jinguang Hu 2022, 74(11): 324-331.  DOI: 10.1016/j.jechem.2022.07.028 Abstract ( 3 )   PDF (7739KB) ( 2 )   Biomass photorefinery to produce fuels and valuable chemicals is a promising approach to alleviating the energy crisis and achieving carbon neutrality. However, precisely modulating the photocatalytic conver-sion of biomass into value-added chemicals is still challenging. Here we demonstrate a feasible strategy to selectively produce arabinose via oriented glucose oxidation to gluconic acid, followed by the decar-boxylation process for C1-C2 bond cleavage. To realize this process, gold nanoparticles (Au NPs) modified carbon nitride (AuCN) is rationally designed to regulate the electron transfer behavior of pristine carbon nitride from a two-electron pathway to a single-electron pathway. This allows selective production of superoxide (.O-2 ) from oxygen reduction reaction which triggers glucose oxidation into gluconic acid. In addition, the arabinose production is synergistically promoted by the improved charge separation effi-ciency and extended visible-light absorption via localized surface plasmon resonance (LSPR) of Au nanoparticles. This work demonstrates an example of a mechanism-guided catalyst design to improve biofuels/chemicals production from biomass photorefinery.

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Decoration of carbon encapsulated nitrogen-rich MoxN with few-layered MoSe2 nanosheets for high-performance sodium-ion storage Tao Lu, Baoquan Liu, Fanyan Zeng, Guo Cheng, Shile Chu, Meilan Xie, Zhi Chen, Zhaohui Hou 2022, 74(11): 332-340.  DOI: 10.1016/j.jechem.2022.07.030 Abstract ( 7 )   PDF (8862KB) ( 8 )   Transition metal nitrides have become the focus of research in sodium ion batteries (SIBs) due to their unique metal properties and high theoretical capacity. However, the low actual capacity is still the main bottleneck for their application. Herein, using Mo-aniline frameworks as precursors, the carbon encapsu-lated nitrogen-rich MoxN is decorated by few-layered MoSe2 nanosheets (MoSe2@MoxN/C-I) after the facile calcinating, selenizing, and nitriding. The carbon encapsulation can effectively strengthen the struc-tural stability of MoxN. The nitrogen-rich MoxN and decoration of few-layered MoSe2 can create rich heterointerfaces and extra active sites for rapid sodium-ion storage, thus promoting reaction kinetics and improving actual capacity. The MoSe2@MoxN/C-I as an anode achieves a large reversible capacity of 522.8 mAh g-1 at 0.1 A g-1, and 254.3 mAh g-1 capacity is obtained after 6000 cycles at 5.0 A g-1, showing signally improved sodium-ion storage properties. The storage mechanisms and kinetic behav-iors are described systematically via the advanced testing techniques and density functional theory (DFT) calculations. It is found that the nitrogen-rich MoxN as the substrate is the basis of long cycling sta-bility, and the few-layered MoSe2 are the key to improving actual capacity. This work indicates that the decoration of few-layered selenides has a broad application prospect in high-performance metal-ion batteries.

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Surface Cu+ modified ZnIn2S4 for promoted visible-light photocatalytic hydrogen evolution Wen Li Jia, Wen Jing Li, Hai Yang Yuan, Xuefeng Wu, Yuanwei Liu, Sheng Dai, Qilin Cheng, Peng Fei Liu, Hua Gui Yang 2022, 74(11): 341-348.  DOI: 10.1016/j.jechem.2022.07.022 Abstract ( 6 )   PDF (5769KB) ( 3 )   Surface modification by metal ion has been considered a promising strategy to enhance the photocat-alytic activity by extending optical response and improving charge separation and transportation. Here, univalent copper species were modified on ZnIn2S4 photocatalyst via an in-situ photodeposition method, exhibiting a much higher H2 evolution rate of 41.10 ± 3.43 mmol gꢀ1 hꢀ1 and an impressive apparent quantum efficiency (AQE) of 20.81% at 420 ± 15 nm. Our characterizations indicate that the sur-face modification by copper species can broaden light utilization as well as promote charge separation and transportation. Besides, the density functional theory (DFT) results further exhibit that the energy levels (LUMO and HOMO) for copper-surface modified ZnIn2S4 present spatial separation, locating on the Zn-S and In-S layers, respectively, which can suppress the recombination of electron and hole and thus achieves higher photocatalytic H2 evolution efficiency.

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A flexible design strategy to modify Ti3C2Tx MXene surface terminations via nucleophilic substitution for long-life Li-S batteries Tianpeng Zhang, Wenlong Shao, Siyang Liu, Zihui Song, Runyue Mao, Xin Jin, Xigao Jian, Fangyuan Hu 2022, 74(11): 349-358.  DOI: 10.1016/j.jechem.2022.07.041 Abstract ( 1 )   PDF (9659KB) ( 1 )   MXene-based materials have gained considerable attention for lithium-sulfur (Li-S) batteries cathode materials due to their superior electric conductivity and high affinitive to polysulfides. However, there are still challenges in modifying the surface functional groups of MXene to further improve the electro-chemical performance and increase the structure variety for MXene-based sulfur host. Herein, we report an efficient and flexible nucleophilic substitution (SN) strategy to modify the Ti3C2Tx surface terminations and purposefully designed Magnolol-modified Ti3C2Tx (M-Ti3C2Tx) as powerful cathode host materials. Benefiting from more C-Ti-O bonds forming and diallyl groups terminations reducing after the dehalo-genation and nucleophilic addition reactions, the given M-Ti3C2Tx electrode could effectively suppress the lithium polysulfides shuttling via chemisorption and CAS covalent bond formation. Besides, the Magnolol-modified Ti3C2Tx significantly accelerates polysulfide redox reaction and reduces the activation energy of Li2S decomposition. As a result, the as-prepared M-Ti3C2Tx electrode displays an excellent rate capability and a high reversible capacity of 7.68 mAh cm-2 even under 7.2 mg cm-2 S-loaded with a low decay rate of 0.07% (from 2nd cycle). This flexible surface-modified strategy for MXene terminations is expected to be extended to other diverse MXene applications.

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Segmented tomographic evaluation of structural degradation of carbon support in proton exchange membrane fuel cells Jung A. Hong, Min-Hyoung Jung, Sung Yong Cho, Eun-Byeol Park, Daehee Yang, Young-Hoon Kim, Sang-Hyeok Yang, Woo-Sung Jang, Jae Hyuck Jang, Hyo June Lee, Sungchul Lee, Hu Young Jeong, Young-Min Kim 2022, 74(11): 359-367.  DOI: 10.1016/j.jechem.2022.07.036 Abstract ( 3 )   PDF (7293KB) ( 2 )   The variation of the three-dimensional (3D) structure of the membrane electrode of a fuel cell during proton exchange cycling involves the corrosion/compaction of the carbon support. The increasing degra-dation of the carbon structure continuously reduces the electrocatalytic performance of proton exchange membrane fuel cells (PEM-FCs). This phenomenon can be explained by performing 3D tomographic anal-ysis at the nanoscale. However, conventional tomographic approaches which present limited experimen-tal feasibility, cannot perform such evaluation and have not provided sufficient structural information with statistical significance thus far. Therefore, a reliable methodology is required for the 3D geometrical evaluation of the carbon structure. Here, we propose a segmented tomographic approach which employs pore network analysis that enables the visualization of the geometrical parameters corresponding to the porous carbon structure at a high resolution. This approach can be utilized to evaluate the 3D structural degradation of the porous carbon structure after cycling in terms of local surface area, pore size distribu-tion, and their 3D networking. These geometrical parameters of the carbon body were demonstrated to be substantially reduced owing to the cycling-induced degradation. This information enables a deeper understanding of the degradation phenomenon of carbon supports and can contribute to the develop-ment of stable PEM-FC electrodes.

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A robust Janus bilayer with tailored ionic conductivity and interface stability for stable Li metal anodes Guodong Zhang, Pengwei Li, Kai Chen, Hongfei Zheng, Wei He, Liangping Xiao, Xingyun Li, Qingchi Xu, Jian Weng, Jun Xu 2022, 74(11): 368-375.  DOI: 10.1016/j.jechem.2022.07.032 Abstract ( 3 )   PDF (7181KB) ( 2 )   The formation and growth of Li-dendrites caused by inhomogeneous Li deposition severely hinder the commercial applications of Li metal batteries due to the consequence of short-circuiting. Herein, we pro-pose a Janus bilayer composed of black phosphorus (BP) and graphene oxide (GO) as an artificial interface with chemical/mechanical stability and well-regulated Li-ion flux distribution for Li metal anode protec-tion. Owing to the synergy between the fast Li-ion transport of BP in the inner layer and the high mechan-ical and chemical stability of GO in the outer layer, the GO/BP with good electrolyte wettability acts as a Li-ion regulator that can induce homogeneous growth of Li to suppress the Li dendrites growth. Accordingly, long-term stability (500 h at 1 mA cm-2) with a low overpotential of 30 mV is achieved in the symmetric cell with GO/BP-Li anode. Furthermore, the Li-S cell with GO/BP-Li exhibits enhanced cycling performance with a high capacity retention rate of 76.2% over 500 cycles at 1 C.

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Bifunctional oxygen electrode cobalt-nickel sulfides catalysts originated from intercalated LDH precursors Xiaofei Gong, Haihong Zhong, Luis Alberto Estudillo-Wong, Nicolas Alonso-Vante, Yongjun Feng, Dianqing Li 2022, 74(11): 376-386.  DOI: 10.1016/j.jechem.2022.07.039 Abstract ( 3 )   PDF (14250KB) ( 3 )   Bimetallic cobalt-nickel sulfide nanoparticles anchored on S-, N-codoped holey carbon nanosheets (CoNi-S-T@NCFs) with a hydrangea-like morphology, were synthesized via a confinement synthesis route, in which an intercalated LDH precursor was subjected to the interlayer-confined carbonization and host-layer sulfurization. The phase transformation and structure evolution (e.g., atom site occupancy, crystallite size, and cell volume) of the CoNi-S-T@NCFs electrocatalysts, as a function of sulfurization tem-peratures, were confirmed by X-ray diffraction and Rietveld analyses. The sulfur vacancies effectively enhance the electrocatalytic activity, while the synergistic effect of (Co,Ni)7S8 alloy and S, N-codoped car-bon matrix facilitates the electron transfer and accelerates reaction kinetics, making CoNi-S-900@NCFs an efficient and stable bifunctional electrocatalyst for oxygen reduction reaction (ORR). The rich high-valence Co (III) and Ni (III) of CoNi-S-900@NCFs facilitates the in-situ transformation of the metal (oxy) hydroxides intermediates with high catalytic activity for oxygen evolution reaction (OER). Thus, with a bifunctional parameter, DE, of 0.75 V (Ej=10, OER -E1/2, ORR), this electrocatalyst slightly outperforms the state-of-the-art commercial Pt/C + RuO2/C catalyst (DE = 0.76 V) in alkaline medium. This work demon-strates the influence that the sulfurization temperature has on the relationship between the structure and electrocatalytic performance of bimetallic sulfides prepared by the synthesis strategy using the interca-lated LDH precursor. This strategy can be extended to prepare other chalcogenides with binary or ternary transition metals.

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Surface passivation and hole extraction: Bifunctional interfacial engineering toward high-performance all-inorganic CsPbIBr2 perovskite solar cells with efficiency exceeding 12% Qi Liu, Junming Qiu, Xianchang Yan, Yuemeng Fei, Yue Qiang, Qingyan Chang, Yi Wei, Xiaoliang Zhang, Wenming Tian, Shengye Jin, Ze Yu, Licheng Sun 2022, 74(11): 387-393.  DOI: 10.1016/j.jechem.2022.07.035 Abstract ( 7 )   PDF (4860KB) ( 3 )   All-inorganic CsPbIBr2 perovskite solar cells (PSCs) have attracted considerable research attention in recent years due to their excellent thermal stability. However, their power conversion efficiencies (PCEs) are relatively low and still far below the theoretical limit. Here, we report the use of an organic dye molecule (namely VG1-C8) as a bifunctional interlayer between perovskite and the hole-transport layer in CsPbIBr2 PSCs. Combined experimental and theoretical calculation results disclose that the mul-tiple Lewis base sites in VG1-C8 can effectively passivate the trap states on the perovskite films. Meanwhile, the p-conjugated dye molecule significantly accelerates the hole extraction from the per-ovskite absorber as evidenced by the photoluminescence analysis. Consequently, the VG1-C8 treatment simultaneously boosts the photovoltage and photocurrent density values from 1.26 V and 10.80 mA cm-2 to 1.31 V and 12.44 mA cm-2, respectively. This leads to a significant enhancement of PCE from 9.20% to 12.10% under one sun irradiation (AM 1.5G). To our knowledge, this is the record efficiency reported so far for CsPbIBr2 PSCs. Thus, the present work demonstrates an effective interfacial passivation strategy for the development of highly efficient PSCs.

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N/S codoping modification based on the metal organic framework-derived carbon to improve the electrochemical performance of different energy storage devices Ziyi Zhu, Xue Li, Zhong Zhang, Qi Meng, Wenjia Zhang, Peng Dong, Yingjie Zhang 2022, 74(11): 394-403.  DOI: 10.1016/j.jechem.2022.07.024 Abstract ( 7 )   PDF (7715KB) ( 8 )   Carbon-based materials have become a research hotspot in the field of energy storage devices in recent years due to their abundant resources, low cost, and environmental friendliness. However, the low capacity and poor high rate performance still constitute great challenges. Metal organic framework-derived carbon has been widely researched because of its high porosity, tunable structure, and good conductivity. In this work, N/S codoped hierarchical porous carbon microspheres were prepared by a high-temperature heat treatment and atomic doping process using a zinc-based organic framework as the precursor. When used as a potassium-ion battery anode, it has a high reversible specific capacity (435.7 mAh g-1), good rate per-formance (133.5 mAh g-1 at 10,000 mA g-1), and long-term cycling stability (73.2% capacity retention after the 2500th cycle). The potassium storage mechanism of the derived carbon was explained by various elec-trochemical analysis methods and microstructure characterization techniques, and the relationship between the structural characteristics and electrochemical properties was researched. In a supercapacitor, the porous carbon material exhibits a specific capacitance of 307.2 F g-1 at a current density of 0.2 A g-1 in a KOH aqueous solution and achieves a retention rate of 99.88% after 10,000 cycles. The assembled symmet-ric supercapacitor device delivers a high energy density of 6.69 Wh kg-1, with a corresponding power den-sity of 2500 W kg-1. In addition, density functional theory calculations further confirmed that N/S codoping can improve the adsorption capacities of potassium and hydroxyl ions in the derived carbon.

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Structural transformation of metal-organic framework with constructed tetravalent nickel sites for efficient water oxidation Weijian Wu, Zhen Gao, Qun Li, Zhiya Wang, Shiyin Liu, Hongbo Wu, Yuanchun Zhao, Yalong Jiao, Xiaojia Zhao 2022, 74(11): 404-411.  DOI: 10.1016/j.jechem.2022.07.040 Abstract ( 6 )   PDF (6391KB) ( 2 )   A mixture of Ni and Fe oxides is among the most commonly active catalysts for the oxygen evolution reaction (OER) during the water oxidation process. In particular, Ni oxide incorporated with even a small amount of Fe leads to substantively enhanced OER activity. However, the critical role of Fe species during the electrocatalytic process is still under evaluation. Herein, we report nickel (oxy)hydroxide incorpo-rated with Fe through the surface reconstruction of a bimetallic metal-organic framework (NiFe-MOF) during the water oxidation process. The spectroscopic investigations with theoretical calculations reveal the critical role of Fe in promoting the formation of highly oxidized Ni4+, which directly correlates with an enhanced OER activity. Both the geometric and electronic structures of the as-reconstructed Ni1-xFexOOH electrocatalysts can be delicately tuned by the Ni-Fe ratio of the bimetallic NiFe-MOF, further affecting the catalytic activity. As a result, the Ni1-xFexOOH derived from Ni0.9Fe0.1-MOF delivers low overpoten-tials of 260 mV at 10 mA cm-2 and 400 mV at 300 mA cm-2.

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Guided lithium nucleation and growth on lithiophilic tin-decorated copper substrate Lang Ye, Chengyi Zhang, Yin Zhou, Burak Ülgüt, Yan Zhao, Jiangfeng Qian 2022, 74(11): 412-419.  DOI: 10.1016/j.jechem.2022.07.027 Abstract ( 7 )   PDF (6584KB) ( 7 )   Lithium metal is the ultimate anode choice for high energy rechargeable lithium batteries owing to its ultra-high theoretical capacity, however, Li dendrites and low Coulombic efficiency (CE) caused by disor-dered Li plating restrict its practical application. Herein, we develop an ultrathin Sn-decorated Cu sub-strate (Sn@Cu) fabricated by an electroless plating method to induce ordered Li nucleation and growth behavior. The lithiophilic Sn interfacial layer is found to play a critical role to lower the Li nucleation over-potential and promote fast Li-migration kinetics, and the underlying mechanism is revealed using the first principle calculations. Accordingly, a dense dendrite-free and Li deposition with large granular morphology is obtained, which significantly improved the CE and cycling performance of Li||Sn@Cu half cells symmetric cells. Symmetric cells using the Li-Sn@Cu electrode display a much-prolonged life span (>1200 h) with low overpotential ( 18 mV) at a high current density of 1 mA cm-2. Moreover, full cells paired with commercial LiFePO4 cathode (1.8 mAh cm-2) deliver enhanced cycling stability (0.5 C, 300 cycles) and excellent rate performance. This work provides a simple and effective way to bring about high efficiency and long lifespan substrates for practical applications.

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Single-phase bimetal sulfide or metal sulfide heterojunction: Which one is better for reversible oxygen electrocatalyst? Jingjing Cai, Huijun Liu, Yulin Luo, Yuqing Xiong, Lizhu Zhang, Sheng Wang, Kang Xiao, Zhao-Qing Liu 2022, 74(11): 420-428.  DOI: 10.1016/j.jechem.2022.07.023 Abstract ( 3 )   PDF (8081KB) ( 5 )   Bimetallic sulfides, integrating the merits of individual components, are ideal structures for efficient elec-trocatalysis. However, for bimetallic sulfides including metal sulfide heterojunctions (MSH) and single-phase bimetallic sulfides (SBS), it is still unclear about which one has better catalytic activity toward reversible oxygen catalysis and its difference on catalytic mechanism. In this work, we demonstrate a bimetallic sulfide electrocatalyst that could transform from metal sulfide heterojunction (CoS/FeS) to single-phase bimetallic sulfide (CoFeS2) through a facile temperature control strategy. The single-phase bimetallic sulfide (CoFeS2) affords high intrinsic activity, fast reaction kinetics and superior durability toward oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Density functional theory (DFT) simulations reveal that the (CoFeS2) has homogeneous electron distribution of the CoFeS2 structure, improves the central energy level of d band, and optimizes the O* and OOH* intermediate and efficiently reduces the energy barrier of the reaction rate-determining step (RDS). The assembled rechargeable zinc-air battery is more stable than the Pt/C and IrO2 assemblies due to the excellent electrocatalytic activity and stability of CoFeS2/NC, suggesting that it has potential for use in practical applications.

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Zeolitic imidazolate framework-67 derived Al-Co-S hierarchical sheets bridged by nitrogen-doped graphene: Incorporation of PANI derived carbon nanorods for solid-state asymmetric supercapacitors Emad S. Goda, Bidhan Pandit, Sang Eun Hong, Bal Sydulu Singu, Seong K. Kim, Essam B. Moustafa, Kuk Ro Yoon 2022, 74(11): 429-445.  DOI: 10.1016/j.jechem.2022.07.033 Abstract ( 9 )   PDF (13738KB) ( 2 )   Metal sulfides have been widely enticed as battery-type electrodes in supercapacitor devices because of their maximal theoretical capacitance. Nevertheless, their lower conductivity and ion transport kinetics can largely restrict their rate performance, hence the practical usage in fields of demanding high power devices. Therefore, the design of new electrodes with higher energy and power densities remains a highly challenging task. To the best of our knowledge, a novel hierarchical composite of Al-CoS2 on nitrogen-doped graphene (NG) is prepared based on a zeolite imidazole framework using a simple and scalable hydrothermal process. In this hybrid, ultrathin Al-CoS2 nanosheet arrays are vertically orientated on the NG framework to limit self-aggregation, hence increasing the electrical property and cycle stability of composite. It is investigated that the Al/Co feeding ratio plays a crucial role in controlling the obtained hierarchical structure of Al-Co-S sheets and their electrode performance. Also, Al3+ can influence remark-ably the morphology and electrochemical property of the resultant graphene composite. An effective syn-ergism is noticed between the redox Al-CoS2 and NG resulting in fast electron transfer and charging-discharging processes. Surprisingly, when the as-developed composite is utilized as a positive electrode at an applied current density of 1 A/g, a specific capacitance of 1915.8 F/g is attained with ultra-long cycle stability (96%, 10,000 cycles) and an excellent retention rate (~89%). As a consequence, when a solid-state asymmetric supercapacitor (ASC) device is made by combining an Al-CoS2@NG hybrid with a negative electrode made of polyaniline (PANI) derived carbon nanorods (PCNRs), it demonstrates remarkable specific capacitance (188 F/g), energy density (66.9 Wh/kg), and cyclic stability of 92% after 10,000 cycles. This may open the pathway for the application of the next-generation supercapacitors in the future.

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Correlating electrochemical performance and heat generation of Li plating for lithium-ion battery with fluoroethylene carbonate additive Wenxin Mei, Lihua Jiang, Hongmin Zhou, Jinhua Sun, Qingsong Wang 2022, 74(11): 446-453.  DOI: 10.1016/j.jechem.2022.07.026 Abstract ( 22 )   PDF (4471KB) ( 18 )

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Methane hydrate formation in porous media: Overview and perspectives Yue Qin, Liyan Shang, Zhenbo Lv, Jianyu He, Xu Yang, Zhien Zhang 2022, 74(11): 454-480.  DOI: 10.1016/j.jechem.2022.07.019 Abstract ( 25 )   PDF (15708KB) ( 10 )   Natural gas hydrate (NGH) has recently received more attention as a cleaner alternative energy source that not only reduces carbon emissions caused by the use of conventional fossil fuels but also plays a key role in global climate change. Furthermore, hydrate-based technologies, particularly hydrate-based carbon capture and storage, have enormous promise for decreasing global carbon emissions, and porous media play an important role in all hydrate-based technologies. Accordingly, this paper reviews the recent applications of porous media in the field of methane hydrate (MH) formation and analyzes the influence of porous media systems on MH phase equilibria and formation kinetics. This is because the efficiency of hydrate-based technologies is determined mainly by the phase equilibrium and formation kinetics of hydrates. The influence of the nature of the media on MH formation in porous media systems is comprehensively summarized to understand how porous media can efficiently enhance the kinetics of hydrate formation. Promoters are necessary for rapid hydrate formation, and the effect of various pro-moters on MH formation was also evaluated. Based on the aforementioned overview and understanding, the mechanisms for MH formation in various porous media systems are proposed. Finally, the future per-spectives and challenges of hydrate-based technologies in tackling global climate change were discussed. This review provides a fundamental understanding of the application and development of porous media in rapid hydrate formation, a fair evaluation of the performance of various porous media systems, and critical insights into major research foci.

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Catalysts for the hydrogen evolution reaction in alkaline medium: Configuring a cooperative mechanism at the Ag-Ag2S-MoS2 interface Avraham Bar-Hen, Simon Hettler, Ashwin Ramasubramaniam, Raul Arenal, Ronen Bar-Ziv, Maya Bar Sadan 2022, 74(11): 481-488.  DOI: 10.1016/j.jechem.2022.07.020 Abstract ( 6 )   PDF (5903KB) ( 3 )   Designing electrocatalysts for HER in alkaline conditions to overcome the sluggish kinetics associated with the additional water dissociation step is a recognized challenge in promoting the hydrogen econ-omy. To this end, delicately tuning the atomic-scale structure and surface composition of nanoparticles is a common strategy and, specifically, making use of hybrid structures, can produce synergistic effects that lead to highly active catalysts. Here, we present a core-shell catalyst of Ag@MoS2 that shows promis-ing results towards the hydrogen evolution reaction (HER) in both 0.5 M H2SO4 and 0.5 M KOH. In this hybrid structure, the MoS2 shell is strained and defective, and charge transfer occurs between the con-ductive core and the shell, contributing to the electrocatalytic activity. The shelling process results in a large fraction of Ag2S in the cores, and adjusting the relative fractions of Ag, Ag2S, and MoS2 leads to improved catalytic activity and fast charge-transfer kinetics. We suggest that the enhancement of alka-line HER is associated with a cooperative effect of the interfaces, where the Ag(I) sites in Ag2S drive the water dissociation step, and the formed hydrogen subsequently recombines on the defective MoS2 shell. This study demonstrates the benefits of hybrid structures as functional nanomaterials and provides a scheme to activate MoS2 for HER in alkaline conditions.

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Chelation of lithium ion with crown ether for eliminating adverse effects caused by Li-TFSI/tBP doping system in Spiro-OMeTAD Zhongquan Wan, Hui Lu, Jinyu Yang, Yunpeng Zhang, Fangyan Lin, Jianxing Xia, Xiaojun Yao, Junsheng Luo, Chunyang Jia 2022, 74(11): 489-496.  DOI: 10.1016/j.jechem.2022.07.038 Abstract ( 14 )   PDF (5845KB) ( 9 )   Lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI)/4-tert-butylpyridine (tBP) is a classic doping sys-tem for the hole transport material Spiro-OMeTAD in typical n-i-p structure perovskite solar cells (PSCs), but this system will cause many problems such as high hygroscopicity, Li+ migration, pinholes and so on, which hinder PSC from maintaining high efficiency and stability for long-term. In this work, an effective strategy is demonstrated to improve the performance and stability of PSC by replacing tBP with 12-crown-4. The chelation of 12-crown-4 with Li+ not only improves the doping effect of Li-TFSI, but also perfectly solves the problems caused by the Li-TFSI/tBP system. The PSC based on this strategy achieved a champion power conversion efficiency (PCE) over 21%, which is significantly better than the pristine device (19.37%). More importantly, the without encapsulated device based on Li-TFSI/12-crown-4 still maintains 87% of the initial PCE even after 60 days exposure in air, while the pristine device only maintains 22% of the initial PCE under the same aging conditions. This strategy paves a novel way for con-structing efficient and stable PSCs.