Enhanced High-Temperature Cycling Stability of Garnet-Based All Solid-State Lithium Battery Using a Multi-Functional Catholyte Buffer Layer

The pursuit of safer and high-performance lithium-ion batteries(LIBs)has triggered extensive research activities on solid-state batteries,while challenges related to the unstable electrode-electrolyte interface hinder their practical implementation.Polymer has been used extensively to improve the cathode-electrolyte interface in garnet-based all-solid-state LIBs(ASSLBs),while it introduces new concerns about thermal stability.In this study,we propose the incorporation of a multi-functional flame-retardant triphenyl phos-phate additive into poly(ethylene oxide),acting as a thin buffer layer between LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)cathode and garnet electro-lyte.Through electrochemical stability tests,cycling performance evaluations,interfacial thermal stability analysis and flammability tests,improved thermal stability(capacity retention of 98.5%after 100 cycles at 60℃,and 89.6%after 50 cycles at 80℃)and safety characteristics(safe and stable cycling up to 100℃)are demonstrated.Based on various materials characterizations,the mechanism for the improved thermal stability of the interface is proposed.The results highlight the potential of multi-functional flame-retardant additives to address the challenges associated with the electrode-electrolyte interface in ASSLBs at high temperature.Efficient thermal modification in ASSLBs operating at elevated temperatures is also essential for enabling large-scale energy storage with safety being the primary concern.

In situ formation of self-antistacking FeCoO_(x) on N-doped graphene:A 3D-on-2D nanoarchitecture for long-life Zn-air batteries

Before the practical application of rechargeable Zn-air batteries(ZABs),a critical issue regarding the inherent slow reaction kinetics of the oxygen reduction(ORR)and oxygen evolution(OER)must be addressed.Here,we fabricate a cost-effective bifunctional oxygen electrocatalyst with a self-antistacking structure,where three-dimensional(3D)Fe-Co bimetallic oxide particles(FeCoO_(x))are directly grown on 2D N-doped graphene(NG).The in situ grown FeCoO_(x)particles can alleviate the NG interlaminar restacking,ensuring abundant channels for diffusion of O_(2)/OH−species,while the NG allows rapid electron flow.Benefiting from this self-antistacking 3D-on-2D structure and synergetic electrocatalysis,FeCoO_(x)@NG demonstrated excellent activity for both ORR and OER(ΔE=0.78 V),which is superior to that of the binary mixtures of Pt/C and RuO_(2)(ΔE=0.83 V).A homemade ZAB with 20%-FeCoO_(x)@NG delivers a specific capacity of 758.9 mAh g^(−1),a peak power density of 215 mW cm^(−2),and long-term cyclability for over 400 h.These research results suggest that designing a bimetallic oxide/N-doped carbon 3D-on-2D nanoarchitecture using an in situ growth strategy is an attractive and feasible solution to overcome electrocatalytic problems in ZABs.

Simultaneously mastering operando strain and reconstruction effects via phase-segregation strategy for enhanced oxygen-evolving electrocatalysis

Material strain and reconstruction effects are critical for catalysis reactions,but current insights into operando strain effects during reaction and means to master catalyst reconstruction are still lacking.Here,we propose a facile thermal-induced phase-segregation strategy to simultaneously master material operando strain and reconstruction effects for enhanced oxygen-evolving reaction(OER).Specifically,self-assembled and controllable layered LiCoO_(2)phase and Co_(3)O_(4)spinel can be generated from pristine Li2Co_(2)O_(4)spinel via Li and O volatilization under different temperatures,realizing controllable proportions of two phases by calcination temperature.Combined operando and ex-situ characterizations reveal that obvious tensile strain along(003)plane appears on layered LixCoO_(2)phase during OER,while low-valence Co_(3)O_(4)phase transforms into high-valence CoOOHx,realizing simultaneous operando strain and reconstruction effects.Further experimental and computational investigations demonstrate that both strained LixCoO_(2)phase and reconstructed CoOOHxcompound contribute to the beneficial adsorption of important OH-reactants,while respective roles in activity and stability are uncovered by exploring their latticeoxygen participation mechanism.This work not only reveals material operando strain effects during OER,but also inaugurates a new thermal-induced phase-segregation strategy to artificially master material operando strain and reconstruction effects,which will enlighten rational material design for many potential reactions and applications.

Electrochemical Water Splitting:Bridging the Gaps Between Fundamental Research and Industrial Applications

Electrochemical water splitting represents one of the most promising technologies to produce green hydrogen,which can help to realize the goal of achieving carbon neutrality.While substantial efforts on a laboratory scale have been made for understanding fundamental catalysis and developing high-performance electrocatalysts for the two half-reactions involved in water electrocatalysis,much less attention has been paid to doing relevant research on a larger scale.For example,few such researches have been done on an industrial scale.Herein,we review the very recent endeavors to bridge the gaps between fundamental research and industrial applications for water electrolysis.We begin by introducing the fundamentals of electrochemical water splitting and then present comparisons of testing protocol,figure of merit,catalyst of interest,and manufacturing cost for laboratory and industry-based water-electrolysis research.Special attention is paid to tracking the surface reconstruction process and identifying real catalytic species under different testing conditions,which highlight the significant distinctions of corresponding electrochemical reconstruction mechanisms.Advances in catalyst designs for industry-relevant water electrolysis are also summarized,which reveal the progress of moving the practical applications forward and accelerating synergies between material science and engineering.Perspectives and challenges of electrocatalyst design strategies are proposed finally to further bridge the gaps between lab-scale research and large-scale electrocatalysis applications.

Novel high-entropy oxides for energy storage and conversion:From fundamentals to practical applications

High-entropy oxides(HEOs)are gaining prominence in the field of electrochemistry due to their distinctive structural characteristics,which give rise to their advanced stable and modifiable functional properties.This review presents fundamental preparations,incidental characterizations,and typical structures of HEOs.The prospective applications of HEOs in various electrochemical aspects of electrocatalysis and energy conversion-storage are also summarized,including recent developments and the general trend of HEO structure design in the catalysis containing oxygen evolution reaction(OER)and oxygen reduction reaction(ORR),supercapacitors(SC),lithium-ion batteries(LIBs),solid oxide fuel cells(SOFCs),and so forth.Moreover,this review notes some apparent challenges and multiple opportunities for the use of HEOs in the wide field of energy to further guide the development of practical applications.The influence of entropy is significant,and high-entropy oxides are expected to drive the improvement of energy science and technology in the near future.

Tuning the charge distribution and crystal field of iron single atoms via iron oxide integration for enhanced oxygen reduction reaction in zinc-air batteries

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 Fe_(2)O_(3) integration via the strong electronic interaction.Remarkably,the optimized catalyst(M-Fe_(2)O_(3)/Fe_(SA)@NC)exhibits excellent activity,durability and good tolerance to methanol,outperforming the benchmark Pt/C catalyst.When M-Fe_(2)O_(3)/Fe_(SA)@NC catalyst was used in a practical zinc-air battery assembly,peak power density of 155 mW cm^(-2)and specific capacity of 762 mA h g_(Zn)^(-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 Fe_(2)O_(3) can evoke the crystal field alteration and electron redistribution on single Fe atoms,which can break the symmetric charge distribution of Fe-N_(4) and thereby optimize the corresponding adsorption energy of intermediates to promote the O_(2)reduction.This study provides a new pathway to promote the catalytic performance of single-atom catalysts.

Beyond two-dimension: One-and zero-dimensional halide perovskites as new-generation passivators for high-performance perovskite solar cells

Perovskite solar cells(PSCs) as a rising star in the photovoltaic field have received rapidly increasing attention recently due to the boosting power conversion efficiencies(PCEs) from 3.8% to 25.7% in the last13 years. Nevertheless, the conventional PSCs with three-dimensional(3D) halide perovskites as light absorbers suffer from inferior PCEs and poor durability under sunlight, high-temperature and humid conditions due to the high defect amount and structural instability of 3D perovskites, respectively. To tackle these crucial issues, lower-dimensional halide perovskites including zero-dimensional(0D), onedimensional(1D), and two-dimensional(2D) perovskites have been employed as efficient passivators to boost the PCEs and durability of 3D-PSCs due to the high structural stability and superior resistance against moisture, heat and sunlight. Therefore, in order to achieve better understanding about the advantages and superiorities of combining low-dimensional perovskites with their 3D counterparts in improving the PCEs and durability of 3D-PSCs, the recent advances in the development and fabrication of mixeddimensional PSCs with 1D/0D perovskites as passivators are summarized and discussed in the review.The superiority of 1D/0D perovskites as passivators over 2D counterparts, the passivation mechanism and the methods of 1D/0D perovskites are also presented and discussed. Furthermore, the rules to choose1D/0D perovskites or relevant spacer cations are also emphasized. On this basis, several specific strategies to design and fabricate mixed-dimensional PSCs with 1D/0D perovskites are presented and discussed.Finally, the crucial challenges and future research directions of mixed-dimensional PSCs with 1D/0D perovskites as passivators are also proposed and discussed. This review will provide some useful insights for the future development of high-efficiency and durable mixed-dimensional PSCs.

In operando-formed interface between silver and perovskite oxide for efficient electroreduction of carbon dioxide to carbon monoxide

Electrochemical carbon dioxide(CO_(2))reduction(ECR)is a promising technology to produce valuable fuels and feedstocks from CO_(2).Despite large efforts to develop ECR catalysts,the investigation of the catalytic performance and electrochemical behavior of complex metal oxides,especially perovskite oxides,is rarely reported.Here,the inorganic perovskite oxide Ag-doped(La_(0.8)Sr_(0.2))_(0.95)Ag_(0.05)MnO_(3-δ)(LSA0.05M)is reported as an efficient electrocatalyst for ECR to CO for the first time,which exhibits a Faradaic efficiency(FE)of 84.3%,a remarkable mass activity of 75Ag^(-1)(normalized to the mass of Ag),and stability of 130 h at a moderate overpotential of 0.79 V.The LSA0.05M catalyst experiences structure reconstruction during ECR,creating the in operando-formed interface between the perovskite and the evolved Ag phase.The evolved Ag is uniformly distributed with a small particle size on the perovskite surface.Theoretical calculations indicate the reconstruction of LSA0.05M during ECR and reveal that the perovskite-Ag interface provides adsorption sites for CO_(2) and accelerates the desorption of the*CO intermediate to enhance ECR.This study presents a novel high-performance perovskite catalyst for ECR andmay inspire the future design of electrocatalysts via the in operando formation of metal-metal oxide interfaces.

Recent advances and perspectives of fluorite and perovskite-based dual-ion conducting solid oxide fuel cells

High-temperature solid-state electrolyte is a key component of several important electrochemical devices,such as oxygen sensors for automobile exhaust control,solid oxide fuel cells(SOFCs) for power generation,and solid oxide electrolysis cells for H_(2) production from water electrolysis or CO_(2) electrochemical reduction to value-added chemicals.In particular,internal diffusion of protons or oxygen ions is a fundamental and crucial issue in the research of SOFCs,hypothetically based on either oxygen-ionconducting electrolytes or proton-conducting electrolytes.Up to now,some electrolyte materials based on fluorite or perovskite structure were found to show certain degree of dual-ion transportation capability,while in available electrolyte database,particularly in the field of SOFCs,such dual-ion conductivity was seriously overlooked.Actually,few concerns arising to the simultaneous proton and oxygen-ion conductivities in electrolyte of SOFCs inevitably induce various inadequate and confusing results in literature.Understanding dual-ion transportation behavior in electrolyte is indisputably of great importance to explain some unusual fuel cell performance as reported in literature and enrich the knowledge of solid state ionics.On the other hand,exploration of novel dual-ion conducting electrolytes will benefit the development of SOFCs.In this review,we provide a comprehensive summary of the understanding of dual-ion transportation in solid electrolyte and recent advances of dual-ion conducting SOFCs.The oxygen ion and proton conduction mechanisms at elevated temperature inside oxide-based electrolyte materials are first introduced,and then(mixed) oxygen ion and proton conduction behaviors of fluorite and perovskite-type oxides are discussed.Following on,recent advances in the development of dual-ion conducting SOFCs based on fluorite and perovskite-type single-phase or composite electrolytes,are reviewed.Finally,the challenges in the development of dual-ion conducting SOFCs are discussed and future prospects are proposed.

Synergistically boosting the elementary reactions over multiheterogeneous ordered macroporous Mo2C/NC-Ru for highly efficient alkaline hydrogen evolution

Simultaneously enhancing the reaction kinetics,mass transport,and gas release during alkaline hydrogen evolution reaction(HER)is critical to minimizing the reaction polarization resistance,but remains a big challenge.Through rational design of a hierarchical multiheterogeneous three-dimensionally(3D)ordered macroporous Mo_(2)C-embedded nitrogen-doped carbon with ultrafine Ru nanoclusters anchored on its surface(OMS Mo_(2)C/NC-Ru),we realize both electronic and morphologic engineering of the catalyst to maximize the electrocatalysis performance.The formed Ru-NC heterostructure shows regulative electronic states and optimized adsorption energy with the intermediate H*,and the Mo_(2)C-NC heterostructure accelerates the Volmer reaction due to the strong water dissociation ability as confirmed by theoretical calculations.Consequently,superior HER activity in alkaline solution with an extremely low overpotential of 15.5 mV at 10 mAcm^(−2)with the mass activity more than 17 times higher than that of the benchmark Pt/C,an ultrasmall Tafel slope of 22.7 mV dec−1,and excellent electrocatalytic durability were achieved,attributing to the enhanced mass transport and favorable gas release process endowed from the unique OMS Mo_(2)C/NC-Ru structure.By oxidizing OMS Mo_(2)C/NC-Ru into OMS MoO_(3)-RuO_(2)catalyst,it can also be applied as efficient oxygen evolution electrocatalyst,enabling the construction of a quasi-symmetric electrolyzer for overall water splitting.Such a device's performance surpassed the state-of-the-art Pt/C||RuO2 electrolyzer.This study provides instructive guidance for designing 3D-ordered macroporous multicomponent catalysts for efficient catalytic applications.

A Porous Nano-Micro-Composite as a High-Performance Bi-Functional Air Electrode with Remarkable Stability for Rechargeable Zinc-Air Batteries

The development of bi-functional electrocatalyst with high catalytic activity and stable performance for both oxygen evolution/reduction reactions(OER/ORR)in aqueous alkaline solution is key to realize practical application of zinc-air batteries(ZABs).In this study,we reported a new porous nano-micro-composite as a bifunctional electrocatalyst for ZABs,devised by the in situ growth of metal-organic framework(MOF)nanocrystals onto the micrometersized Ba0.5Sr0.5Co0.8Fe0.2O3(BSCF)perovskite oxide.Upon carbonization,MOF was converted to porous nitrogen-doped carbon nanocages and ultrafine cobalt oxides and CoN4 nanoparticles dispersing inside the carbon nanocages,which further anchored on the surface of BSCF oxide.We homogeneously dispersed BSCF perovskite particles in the surfactant;subsequently,ZIF-67 nanocrystals were grown onto the BSCF particles.In this way,leaching of metallic or organic species in MOFs and the aggregation of BSCF were effectively suppressed,thus maximizing the number of active sites for improving OER.The BSCF in turn acted as catalyst to promote the graphitization of carbon during pyrolysis,as well as to optimize the transition metal-tocarbon ratio,thus enhancing the ORR catalytic activity.A ZAB fabricated from such air electrode showed outstanding performance with a potential gap of only 0.83 V at 5 mA cm-2 for OER/ORR.Notably,no obvious performance degradation was observed for the continuous charge-discharge operation for 1800 cycles over an extended period of 300 h.

Self-catalyzed formation of strongly interconnected multiphase molybdenum-based composites for efficient hydrogen evolution

Molybdenum carbide(MoxC)with variable phase structure possesses flexible hydrogen-binding energy(HBE),which is a promising hydrogen evolution reaction(HER)catalyst.Herein,a hybrid multiphase MoxC freestanding film coupled with Co3Mo(CM/MoxC@NC)is synthesized through the electrospinning method supplemented by the heteroatom incorporation.CM/MoxC@NC surpasses its pure phase counterparts and exhibits remarkable catalytic activity at 114mV to deliver a current density of 10mA cm^(−2) in acid,which is among the first-rate level performance reported for MoxC-based catalysts.The subsequent ex situ and in situ characterizations reveal a phase transition mechanism based on self-catalysis that CoOx depletes the coordinated C ofα-MoC via the interaction,which realizes the assembly of weak HBEα-MoC and strong HBEβ-Mo2C,and the enhanced utilization of active materials as well.The multiple structures with optimal HBE are in favor of the stepwise reactions of HER,as the study of the correlation between HBE and phase structure revealed.This study discloses the underlying phase transition mechanism and highlights the HBE–structure relationship that should be considered for catalyst design.

Chlorine-anion doping induced multi-factor optimization in perovskites for boosting intrinsic oxygen evolution

The oxygen evolution reaction(OER) plays a crucial role in many electrochemical energy technologies,and creating multiple beneficial factors for OER catalysis is desirable for achieving high catalytic efficiency.Here,we highlight a new halogen-chlorine(Cl)-anion doping strategy to boost the OER activity of perovskite oxides.As a proof-of-concept,proper Cl doping at the oxygen site of LaFeO3(LFO) perovskite can induce multiple favorable characteristics for catalyzing the OER,including rich oxygen vacancies,increased electrical conductivity and enhanced Fe-O covalency.Benefiting from these factors,the LaFeO2.9-δCl0.1(LFOCl) perovskite displays significant intrinsic activity enhancement by a factor of around three relative to its parent LFO.This work uncovers the effect of Cl-anion doping in perovskites on promoting OER performance and paves a new way to design highly efficient electrocatalysts.

Direct growth of ordered N-doped carbon nanotube arrays on carbon fiber cloth as a free-standing and binder-free air electrode for flexible quasi-solid-state rechargeable Zn-Air batteries

The development of an air electrode that is flexible in physical property and highly active and durable at different geometric status for both oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is of crucial importance for the rational design of flexible rechargeable Zn-air batteries(ZABs).Considering their good elasticity,high conductivity,and superior thermal and chemical stability,carbon nanotubes have been widely used as a catalyst support in various electrocatalysts,while oxide or metal nanoparticles have been frequently deposited on the carbon nanotube substrate to perform as the active materials.Considering the poor contact between active materials and carbon nanotubes may introduce a challenge for long-term operating stability,in particular in flexible devices,pure carbon electrocatalyst is highly appreciated.Herein,a free-standing air electrode with cobalt nanoparticles encapsulated N-codoped carbon nanotube arrays uniformly grown on the surface of carbon fiber cloth is developed by a two-step in situ growth method.Such a carbon-based electrode shows outstanding activity for both ORR and OER.The flexible ZAB with such air electrode shows superior flexibility and stability working under extreme bending conditions.Moreover,the polarization and round-trip efficiency for the flexible battery is 0.67 V and 64.4%at 2 mA/cm2,respectively,even after being operated for 30 hours.This study provides a feasible way to design all carbon-based free-standing and flexible electrode and enlightens the electrode design for flexible energy conversion/storage devices.

High-Entropy Perovskite Oxide: A New Opportunity for Developing Highly Active and Durable Air Electrode for Reversible Protonic Ceramic Electrochemical Cells

Reversible proton ceramic electrochemical cell(R-PCEC)is regarded as the most promising energy conversion device,which can realize efficient mutual conversion of electrical and chemical energy and to solve the problem of large-scale energy storage.However,the development of robust electrodes with high catalytic activity is the main bottleneck for the commercialization of R-PCECs.Here,a novel type of high-entropy perovskite oxide consisting of six equimolar metals in the A-site,Pr_(1/6)La_(1/6)Nd_(1/6)Ba_(1/6)Sr_(1/6)Ca_(1/6)CoO_(3−δ)(PLN-BSCC),is reported as a high-performance bifunctional air electrode for R-PCEC.By harnessing the unique functionalities of multiple ele-ments,high-entropy perovskite oxide can be anticipated to accelerate reaction rates in both fuel cell and electrolysis modes.Especially,an R-PCEC utilizing the PLNBSCC air electrode achieves exceptional electrochemical performances,demonstrating a peak power density of 1.21 W cm^(−2)for the fuel cell,while simultaneously obtaining an astonishing current density of−1.95 A cm^(−2)at an electrolysis voltage of 1.3 V and a temperature of 600℃.The significantly enhanced electrochemical performance and durability of the PLNBSCC air electrode is attributed mainly to the high electrons/ions conductivity,fast hydration reactivity and high configurational entropy.This research explores to a new avenue to develop optimally active and stable air electrodes for R-PCECs.

Electrodeposition of a dendrite-free 3D Al anode for improving cycling of an aluminum-graphite battery

Aluminum-metal batteries show great potential as next-generation energy storage due to their abundant resources and intrinsic safety.However,the crucial limitations of metallic Al anodes,such as dendrite and corrosion problems in conventional aluminum-metal batteries,remain challenging and elusive.Here,we report a novel electrodeposition strategy to prepare an optimized 3D Al anode on carbon cloth with an uniform deposition morphology,low local current density,and mitigatory volume change.The symmetrical cells with the 3D Al anode show superior stable cycling(>450 h)and low-voltage hysteresis(~170 mV)at 0.5 mA cm^(−2).High reversibility(~99.7%)is achieved for the Al plating/stripping.The graphite||Al‐4/CC full batteries show a long lifespan of 800 cycles with 54 mAh g^(−1) capacity at a high current density of 1000 mA g^(−1),benefiting from the high capacitive-controlled distribution.This study proposes a novel strategy to design 3D Al anodes for metallic-Al-based batteries by eliminating the problems of planar Al anodes and realizing the potential applications of aluminum-graphite batteries.

Tailoring structural properties of carbon via implanting optimal co nanoparticles in n-rich carbon cages toward high-efficiency oxygen electrocatalysis for rechargeable zn-air batteries

Rational construction of carbon-based materials with high-efficiency bifunctionality and low cost as the substitute of precious metal catalyst shows a highly practical value for rechargeable Zn-air batteries(ZABs)yet it still remains challenging.Herein,this study employs a simple mixing-calcination strategy to fabricate a high-performance bifunctional composite catalyst composed of N-doped graphitic carbon encapsulating Co nanoparticles(Co@NrC).Benefiting from the core-shell architectural and compositional advantages of favorable electronic configuration,more exposed active sites,sufficient electric conductivity,rich defects,and excellent charge transport,the optimal Co@NrC hybrid(Co@NrC-0.3)presents outstanding catalytic activity and stability toward oxygen-related electrochemical reactions(oxygen reduction and evolution reactions,i.e.,ORR and OER),with a low potential gap of 0.766 V.Besides,the rechargeable liquid ZAB assembled with this hybrid electrocatalyst delivers a high peak power density of 168 mW cm^(−2),a small initial discharge-charge potential gap of 0.45 V at 10 mA cm^(−2),and a good rate performance.Furthermore,a relatively large power density of 108 mW cm^(−2) is also obtained with the Co@NrC-0.3-based flexible solid-state ZAB,which can well power LED lights.Such work offers insights in developing excellent bifunctional electrocatalysts for both OER and ORR and highlights their potential applications in metal-air batteries and other energy-conversion/storage devices.

A Highly Ordered Hydrophilic–Hydrophobic Janus Bi-Functional Layer with Ultralow Pt Loading and Fast Gas/Water Transport for Fuel Cells

One of the critical challenges that limit broad commercialization of proton exchange membrane fuel cells(PEMFC)is to reduce the usage of Pt while maintaining high power output and sufficient durability.Herein,a novel bifunctional layer consisting of vertically aligned carbon nanotubes(VACNTs)and nanoparticles of Pt-Co catalysts(Pt-Co/VACNTs)is reported for highperformance PEMFCs.Readily prepared by a two-step process,the Pt-Co/VACNTs layer with a hydrophilic catalyst-loaded side and a hydrophobic gas diffusion side enables a PTFE-free electrode structure with fully exposed catalyst active sites and superior gas–water diffusion capability.When tested in a PEMFC,the bi-functional Pt-Co/VACNTs layer with ultralow Pt loading(~65μgcathodecm-2)demonstrates a power density of 19.5 kW gPt cathode-1 at 0.6 V,more than seven times that of a cell with commercial Pt/C catalyst(2.7 kW gPt cathode-1 at 0.6 V)at a loading of 400μgcathodecm-2 tested under similar conditions.This remarkable design of VACNTs-based catalyst with dual functionalities enables much lower Pt loading,faster mass transport,and higher electrochemical performance and stability.Further,the preparation procedure can be easily scaled up for low-cost fabrication and commercialization.

Enhanced coking resistance of a Ni cermet anode by a chromates protective layer

Ni-based anodes of SOFCs are susceptible to coking, which greatly limits practical application of direct methane-based fuels. An indirect internal reformer is an effective way to convert methane-based fuels into syngas before they reach anode. In this work, catalytic activity of a redox-stable perovskite La0.7Sr0.3Cr0.8Fe0.2O3-δ(LSCrFO) for methane conversion was evaluated. The catalyst was fabricated as an anodic protective layer to improve coking resistance of a Ni cermet anode. Using wet CH4 as a fuel, the LSCrFO-modified cell showed excellent power output and good coking resistance with peak power density of 1.59 W cm-2 at 800℃. The cell demonstrated good durability lasting for at least 100 h. While the bare cell without the protective layer showed poor durability with the cell voltage fast dropped from 0.75 V to 0.4 V within 30 min. Under wet coal bed methane (CBM) operation, obvious performance degradation within 35 h (1.7 mV h^-1) was observed due to the influence of heavy carbon compounds in CBM. The pre-and post-mortem microstructures and carbon analysis of the anode surface and catalyst surface were further conducted.

Designing single-atom catalysts toward improved alkaline hydrogen evolution reaction

Electrochemical water splitting powered by renewables-generated electricity represents a promising approach for green hydrogen production.However,the sluggish kinetics for the hydrogen evolution reaction(HER)under an alkaline medium causes a massive amount of energy losses,hindering large-scale production.Exploring efficient and low-cost catalyst candidates for large-scale H_(2) generation becomes a crucial demand.Single-atom catalysts(SACs)demonstrate great promise for enabling efficient alkaline HER catalysis at maximum atom utilization efficiency.In this review,we provide a comprehensive overview of the recent progress in SACs for the HER application in alkaline environments.The fundamentals of alkaline HER are first introduced,followed by a justification of the need to develop SACs.The rational design of the SACs including the inherent element property,coordination environment,SAC morphology,and SAC mass loading are highlighted.To facilitate the development of SACs for alkaline HER,we further propose the remaining challenges and perspectives in this research field.