The development of economical,highly efficient,and stable bifunctional electrocatalysts for both the oxygen evolution reaction(OER)and the oxygen reduction reaction(ORR)remains a critical focus in advancing rechargeab...The development of economical,highly efficient,and stable bifunctional electrocatalysts for both the oxygen evolution reaction(OER)and the oxygen reduction reaction(ORR)remains a critical focus in advancing rechargeable metal-air battery systems.Significant progress has been made in the design of high-performance bifunctional electrocatalysts,the development of novel oxygen electrode architectures,and the in-depth understanding of electrocatalytic mechanisms through combined experimental and computational studies.This work provides a comprehensive review of recent advancements in design strategies for oxygen catalysts,including homogeneous electrodes,asymmetric electrodes,and biomimetic electrodes,are thoroughly discussed and summarized.Then,the advanced catalyst modification strategies for ORR/OER are summarized,focusing on critical factors such as enhancement effect of metal/nonmental and synergistic enhancement effect in multiple catalyst.Subsequently,a representative performance evaluation is presented,based on the reported oxygen electrodes used in rechargeable metal-air battery applications.By focusing on these key areas,the review outlines the current challenges and future prospects for the development of bifunctional oxygen electrocatalysts,aiming to guide the design of high-performance bifunctional electrocatalysts and to elucidate the underlying mechanisms involved.展开更多
Development of high-efficiency bifunctional oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)electrocatalysts is vital for the widespread application of zinc-air batteries(ZABs).However,it still remains...Development of high-efficiency bifunctional oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)electrocatalysts is vital for the widespread application of zinc-air batteries(ZABs).However,it still remains a great challenge to avoid the inhomogeneous distribution and aggregation of metal single-atomic active centers in the construction of bifunctional electrocatalysts with atomically dispersed multimetallic sites because of the common calcination method.Herein,we report a novel catalyst with phthalocyanine-assembled Fe-Co-Ni single-atomic triple sites dispersed on sulfur-doped graphene using a simple ultrasonic procedure without calcination,and X-ray absorption fine structure(XAFS),aberration-corrected scanning transmission electron microscopy(AC-STEM),and other detailed characterizations are performed to demonstrate the successful synthesis.The novel catalyst shows extraordinary bifunctional ORR/OER activities with a fairly low potential difference(ΔE=0.621 V)between the OER overpotential(Ej10=315 mV at 10 m A cm^(-2))and the ORR half-wave potential(Ehalf-wave=0.924 V).Moreover,the above catalyst shows excellent ZAB performance,with an outstanding specific capacity(786 mAh g^(-1)),noteworthy maximum power density(139 mW cm^(-2)),and extraordinary rechargeability(discharged and charged at 5 mA cm^(-2) for more than 1000 h).Theoretical calculations reveal the vital importance of the preferable synergetic coupling effect between adjacent active sites in the Fe-Co-Ni trimetallic single-atomic sites during the ORR/OER processes.This study provides a new avenue for the investigation of bifunctional electrocatalysts with atomically dispersed trimetallic sites,which is intended for enhancing the ORR/OER performance in ZABs.展开更多
ABO_(3)-type perovskite oxides(e.g.,LaCoO_(3))with flexible and adjustable A-and B-sites are ideal model catalysts to unravel the relationship between the electronic structure and electrocatalytic activity(e.g.,oxygen...ABO_(3)-type perovskite oxides(e.g.,LaCoO_(3))with flexible and adjustable A-and B-sites are ideal model catalysts to unravel the relationship between the electronic structure and electrocatalytic activity(e.g.,oxygen reduction/evolution reactions,ORR/OER).It has been well understood in our recent work that the secondary metal dopant at B-site(e.g.,Mn in LaMn_(x)Co_(1-x)O_(3))can regulate the electronic structure and improve the ORR/OER activity.In this work,the Mn-Ni pairs are employed as the dual dopant in LaMn_(x)Ni_(y)Co_(z)O_(3)(x+y+z=1)catalysts toward bifunctional ORR and OER.The structure-property relationships between the triple metal B-site(Mn,Ni and Co)and the electrochemical performance are particularly investigated.Compared to the individual Mn doping(e.g.,LaMnCoO3(Mn:Co=1:3)catalyst),the dual Mn-Ni doping significantly improves the ORR mass activity@0.8 V by 1.54 times;meanwhile,the OER overpotential@10 mA cm^(-2) is reduced from 420 to 370 mV,and the OER current density at 1.55 V is increased by 2.43 times.Reasonably,the potential gap between EDRR@-1 mA cm^(-2) and EDER@10 mA cm^(-2) is achieved as only 0.76 V by using the optimal LaMn_(x)Ni_(y)Co_(z)O_(3)(x:y:z=1:2:3)catalyst.It is revealed that the dual Mn-Ni dopant efficiently optimizes electron structures of the LaMnNiCoO_(3)(1:2:3)catalyst,which not only decreases the e_(g) orbital electron number,but also modulates the O 2 p-band closer to the Femi level,accounting for the enhanced bifunctional activity.展开更多
Silica nanoparticles-stabilized cobalt and nitrogen-doped carbon materials were synthesized through pyrolysis of metal-organic-framework of ZIF-67 supported by silica nanoparticles.The experimental results reveal that...Silica nanoparticles-stabilized cobalt and nitrogen-doped carbon materials were synthesized through pyrolysis of metal-organic-framework of ZIF-67 supported by silica nanoparticles.The experimental results reveal that the introduction of the silica nanoparticles can stabilize the microstructure of the derived CoN-C materials,which in turn exhibits the promising electrocatalytic activity towards both oxygen reduction and oxygen evolution reactions.The optimized sample exhibits a better oxygen reduction activity than commercial Pt/C catalyst as confirmed by the positive shift of half-wave potential by 20 mV while it has a low overpotential of 273 mV for oxygen evolution reactions with the retained performance over 80%after 25,000 s of continuous operation.It is demonstrated that the introduction of support frame might be an effective way to improve the activity and stability of metal-organic-framework derived electrocatalyst with stabilized microstructure.展开更多
The hydrogen reduction kinetics of tungsten trioxide(WO_(3))was investigated via non-isothermal thermogravimetric analysis.Under the local gas-solid reduction conditions,the particle morphology of tungsten powders was...The hydrogen reduction kinetics of tungsten trioxide(WO_(3))was investigated via non-isothermal thermogravimetric analysis.Under the local gas-solid reduction conditions,the particle morphology of tungsten powders was found to be consistent with that of raw material WO_(3).The removal of oxygen from tungsten oxide during hydrogen reduction led to the formation of porous structures between the reduced particles,which were obviously different from the polyhedral single-crystal configuration of tungsten powders obtained via chemical vapor deposition.Moreover,the two-stage hydrogen reduction mechanisms of WO_(3) under the local gas-solid reduction conditions can be described using the composite autocatalytic function.The activation energies of the first and second stages of the hydrogen reduction of WO_(3) were determined to be 121 and 135 kJ/mol,respectively.展开更多
The scaling-up of electrochemical CO_(2)reduction requires circumventing the CO_(2)loss as carbonates under alkaline conditions.Zero-gap MEA cell configurations with a proton exchange membrane represent an alternative...The scaling-up of electrochemical CO_(2)reduction requires circumventing the CO_(2)loss as carbonates under alkaline conditions.Zero-gap MEA cell configurations with a proton exchange membrane represent an alternative solution in a pure acidic system,but the catalyst layer in direct contact with the hydrated proton environment usually leads to H_(2)evolution dominating.Herein,we show that polydimethyldiallyl-ammonium-chloride-coated Ag(Ag@PDDA)electrode exhibits outstanding performance with a FE of 86%,a single-pass conversion of 72%,and a stability of 28 h for CO production in pure-acid MEA compared with ammonium poly(N-methyl-piperidine-co-pterphenyl)decorated Ag(Ag/QAPPT)and cetyltrimethylammonium bromide decorated Ag(Ag/CTAB).The in situ ATR-SEIRAS reveal that PDDA creates a positive charge-rich protective outer layer and an N-rich hybrid inner layer,which not only suppresses the migration of H+during the electrolysis process and blocks the direct contact between H2O and Ag catalyst,but also promotes the generation from CO_(2)to*COOH in a pure-acid system.This work highlights the importance of polyelectrolyte engineering in regulating the electrocatalytic interface and accelerates the development of proton exchange membrane CO_(2)electrolysis.展开更多
We report an in situ preparation of ultrasmall Co–Mn–O spinel nanoparticles(4.4 nm)supported on nonoxidized carbon nanotubes(denoted as CMO@CNTs)as a bifunctional catalyst for oxygen reduction and evolution reaction...We report an in situ preparation of ultrasmall Co–Mn–O spinel nanoparticles(4.4 nm)supported on nonoxidized carbon nanotubes(denoted as CMO@CNTs)as a bifunctional catalyst for oxygen reduction and evolution reactions(ORR/OER).The preparation process involves the oxidization of divalent metal ions under alkaline conditions and the decomposition of nitrates in aqueous solution containing dispersed non-oxidized CNTs.The synthesized CMO nanoparticles strongly couple with the non-oxidized CNTs,which facilitates electron transfer and improves the catalytic activity.Other composites such as CMO@reduced graphene oxide,CMO@Vulcan X-72R,CMO@oxidized CNTs,and a physical mixture of CMO and CNTs were also prepared for comparison.Remarkably,CMO@CNTs exhibit a half wave potential of 0.91 V in 1 M KOH and higher kinetic current and better catalytic durability than Pt/C.Moreover,CMO@CNTs afford an electrocatalytic OER current density of 10 mA cm^(−2) at a low potential of 1.5 V and a small Tafel slope of 81.1 mV dec^(−1).Furthermore,CMO@CNTs display lower discharge/charge overpotential and more stable voltage plateau on cycling than that of Pt/C when employed as a cathode material in rechargeable Zn–air cells.This work indicates that CMO@CNTs are a promising,cheap and efficient bifunctional ORR/OER electrocatalyst for rechargeable metal–air batteries.展开更多
Chiral benzylic amines are important motifs in medicines.A dicationic nickel complex of chiral diphosphine(R)-Ph-BPE promotes highly enantioselective reductive amination of aryl alkyl ketones with arylamines using iso...Chiral benzylic amines are important motifs in medicines.A dicationic nickel complex of chiral diphosphine(R)-Ph-BPE promotes highly enantioselective reductive amination of aryl alkyl ketones with arylamines using isopropanol as hydrogen source.The reaction is easily scaled up in a gram-scale synthesis using 1 mol% nickel catalyst and it is applied to an asymmetric synthesis of(S)-rivastigmine.Building on this success,we achieved rare examples of asymmetric hydrogen borrowing reactions with arylamines using an Earth-abundant 3d metal,nickel.展开更多
Against the background of“carbon peak and carbon neutrality,”it is of great practical significance to develop non-blast furnace ironmaking technology for the sustainable development of steel industry.Carbon-bearing ...Against the background of“carbon peak and carbon neutrality,”it is of great practical significance to develop non-blast furnace ironmaking technology for the sustainable development of steel industry.Carbon-bearing iron ore pellet is an innovative burden of direct reduction ironmaking due to its excellent self-reducing property,and the thermal strength of pellet is a crucial metallurgical property that affects its wide application.The carbon-bearing iron ore pellet without binders(CIPWB)was prepared using iron concentrate and anthracite,and the effects of reducing agent addition amount,size of pellet,reduction temperature and time on the thermal compressive strength of CIPWB during the reduction process were studied.Simultaneously,the mechanism of the thermal strength evolution of CIPWB was revealed.The results showed that during the low-temperature reduction process(300-500℃),the thermal compressive strength of CIPWB linearly increases with increasing the size of pellet,while it gradually decreases with increasing the anthracite ratio.When the CIPWB with 8%anthracite is reduced at 300℃for 60 min,the thermal strength of pellet is enhanced from 13.24 to 31.88 N as the size of pellet increases from 8.04 to 12.78 mm.Meanwhile,as the temperature is 500℃,with increasing the anthracite ratio from 2%to 8%,the thermal compressive strength of pellet under reduction for 60 min remarkably decreases from 41.47 to 8.94 N.Furthermore,in the high-temperature reduction process(600-1150℃),the thermal compressive strength of CIPWB firstly increases and then reduces with increasing the temperature,while it as well as the temperature corresponding to the maximum strength decreases with increasing the anthracite ratio.With adding 18%anthracite,the thermal compressive strength of pellet reaches the maximum value at 800℃,namely 35.00 N,and obtains the minimum value at 1050℃,namely 8.60 N.The thermal compressive strength of CIPWB significantly depends on the temperature,reducing agent dosage,and pellet size.展开更多
Hydrogen evolution reaction(HER)is unavoidable in many electrochemical synthesis systems,such as CO_(2)reduction,N2reduction,and H_(2)O_(2)synthesis.It makes those electrochemical reactions with multiple electron-prot...Hydrogen evolution reaction(HER)is unavoidable in many electrochemical synthesis systems,such as CO_(2)reduction,N2reduction,and H_(2)O_(2)synthesis.It makes those electrochemical reactions with multiple electron-proton transfers more complex when determining kinetics and mass transfer information.Understanding how HER competes with other electrochemical reduction reactions is crucial for both fundamental studies and system performance improvements.In this study,we employed the oxygen reduction reaction(ORR)as a model reaction to investigate HER competition on a polycrystalline-Au surface,using a rotating ring and disk electrode.It’s proved that water molecules serve as the proton source for ORR in alkaline,neutral,and even acidic electrolytes,and a 4-electron process can be achieved when the overpotential is sufficiently high.The competition from H⁺reduction becomes noticeable at the H⁺concentration higher than 2 mmol L^(–1)and intensi-fies as the H^(+)concentration increases.Based on the electrochemical results,we obtained an equivalent circuit diagram for the ORR system with competition from the H+reduction reaction,showing that these reactions occur in parallel and compete with each other.Electrochemical impedance spectroscopy measurements further confirm this argument.Additionally,we discover that the contribution of H+mass transfer to the total H^(+)reduction current is significant and comparable to the kinetic current.We believe this work will deepen our understanding of HER and its competition in electrochemical reduction systems.展开更多
Artificial carbon fixation is a promising pathway for achieving the carbon cycle and environment remediation.However,the sluggish kinetics of oxygen evolution reaction(OER)and poor selectivity of CO_(2) reduction seri...Artificial carbon fixation is a promising pathway for achieving the carbon cycle and environment remediation.However,the sluggish kinetics of oxygen evolution reaction(OER)and poor selectivity of CO_(2) reduction seriously limited the overall conversion efficiencies of solar energy to chemical fuels.Herein,we demonstrated a facile and feasible strategy to rationally regulate the coordination environment and electronic structure of surface-active sites on both photoanode and cathode.More specifically,the defect engineering has been employed to reduce the coordination number of ultrathin FeNi catalysts decorated on BiVO4 photoanodes,resulting in one of the highest OER activities of 6.51 mA cm^(−2)(1.23 VRHE,AM 1.5G).Additionally,single-atom cobalt(II)phthalocyanine anchoring on the N-rich carbon substrates to increase Co–N coordination number remarkably promotes CO_(2) adsorption and activation for high selective CO production.Their integration achieved a record activity of 109.4μmol cm^(−2) h−1 for CO production with a faradaic efficiency of>90%,and an outstanding solar conversion efficiency of 5.41%has been achieved by further integrating a photovoltaic utilizing the sunlight(>500 nm).展开更多
Inspired by hexaazanaphthalene-based conjugated copper metal-organic framework(HATNA-Cu-MOF),we designed 161 HATNA-TM-MOF-based SACs(TM@N_(x)O_(4-x)-HATNA)with varying TM or ligands creating distinct coordination envi...Inspired by hexaazanaphthalene-based conjugated copper metal-organic framework(HATNA-Cu-MOF),we designed 161 HATNA-TM-MOF-based SACs(TM@N_(x)O_(4-x)-HATNA)with varying TM or ligands creating distinct coordination environments(x=0-4)with superior thermodynamic and electrochemical stabilities.Volcano plots can be constructed using(AGOOH^(*)-ΔGO^(*))/ΔGO^(*)as descriptors for oxygen evolution/reduction reaction(OER/ORR)activity,also serving as target parameters for machine learning(ML)models to identify high-performance OER/ORR catalysts.The efficient monofunctional and bifunctional electrocatalysts were successfully predicted,where the ML prediction results well matched the DFT calculation results.We employed Shapley additive explanations(SHAP)for feature analysis and utilized sure independence screening and sparsification operator(SISSO)for generalization.ML analyses reveal that TM-based OER/ORR activities predominantly correlate with three key descriptors:metallic atomic radius,d-orbital electron population,and the heat of formation of the oxide,demonstrating the pivotal role of TM's inherent electronic configuration and physicochemical characteristics in governing electrocatalytic efficacy.The constant-potential approach emphasizes the key role of electric double-layer capacitance in adjusting the kinetic barrier,where changes in the Fermi level influence the occupation of d-orbitals.Variations in electrochemical potential significantly alter the electronic structure of representative Rh@N_(1)O_(3)-HATNA,affecting both the Fermi level and adsorption properties,with the unique 4d^(8)5s^(1)configuration leading to inverted O_(2)adsorption energies as the potential decreases.This study contributes insights into the origin of oxygen evolution-reduction activity for the HATNA-TM-MOF-based SACs and reveals the fundamentals of structure-activity relationships for future applications.展开更多
The development of single atom catalysts(SACs)with asymmetric active sites by defect regulation provides an encourage potential for oxygen reduction reaction(ORR)and hydrogen evolution reaction(HER),but highly challen...The development of single atom catalysts(SACs)with asymmetric active sites by defect regulation provides an encourage potential for oxygen reduction reaction(ORR)and hydrogen evolution reaction(HER),but highly challenging.Herein,N-doped carbon(N-C)anchored atomically dispersed Ni-N_(3)site with proximity defects(Ni-N_(3)D)induced by Te atoms doping is reported.Benefitting from the inductive effect of proximity defect,the Ni-N_(3)D/Te-N-C catalyst performs excellent ORR and HER performance in alkaline and acid condition.Both in situ characterization and theoretical calculation reveal that the existence of proximity defect effect is conducive to lower rate-determining-step energy barrier of ORR and HER,thus accelerating the multielectron reaction kinetics.This work paves a novel strategy for constructing highactivity bifunctional SACs by defect engineering for development of sustainable energy.展开更多
A novel photocatalytic cocatalyst, MoC quantum dots integrated into N-doped carbon microflowers (MoC–NC), was synthesized, establishing a key Mo–N interfacial bond. The Mo–N bond's regulation was achieved by ad...A novel photocatalytic cocatalyst, MoC quantum dots integrated into N-doped carbon microflowers (MoC–NC), was synthesized, establishing a key Mo–N interfacial bond. The Mo–N bond's regulation was achieved by adjusting the pH of Mo-polydopamine precursor solutions. A composite photocatalyst, MoC–NC/CdS (MNS), was formed by in situ growth of nano-CdS on MoC–NC. The pH during synthesis, crucial for Mo–N bond formation, significantly influenced Cr(Ⅵ) reduction and H_(2) evolution performance. The optimal MNS, created at pH 9.0, demonstrated 99.2% reduction efficiency for Cr(Ⅵ) in 20 min and H_(2) evolution rate of 11.4 mmol g^(-1) h^(-1) over 3 h, outperforming Pt/CdS. Mechanistic studies and density functional theory revealed MoC–NC's role in enhancing light absorption, reaction kinetics, and electron transport, attributing to its ultra-small quantum dots and abundant Mo–N bonds.展开更多
Optimizing active sites and enhancing mass transfer capability are of paramount importance for the improvement of electrocatalyst activity.On this basis,CoFe_(2)O_(4)/CoFe nanoparticles(NPs)loaded N-doped carbon(NC)th...Optimizing active sites and enhancing mass transfer capability are of paramount importance for the improvement of electrocatalyst activity.On this basis,CoFe_(2)O_(4)/CoFe nanoparticles(NPs)loaded N-doped carbon(NC)that featured with interconnected three-dimensional(3D)ordered porous hierarchies(3DOM FeCo/NC)are prepared,and its electrocatalytic activity is studied.Due to the open structure of 3D ordered macro-pores that greatly improves the mass transfer capacity of the catalytic process and enhances the utilization of active sites inside the catalyst,as well as the uniform distribution of Fe and Co bimetallic sites on the porous skeleton,3DOM FeCo/NC exhibits superior bi-functional catalytic activities for both hydrogen evolution reaction(HER)and oxygen reduction reaction(ORR).The overpotential of HER is lower than that of commercial Pt/C when performed at high current density(>235 mA cm^(-2))in1.0 M KOH,and the half-wave potential(0.896 V)of ORR in 0.1 M KOH is also superior to that of 20% commercial Pt/C and most other similar catalysts.The effective utilization and synergistic effect of CoFe_(2)O_(4)and CoFe hetero-metallic sites remarkably enhance the electrocatalytic activity.Furthermore,3DOM FeCo/NC is assembled as an air electrode in Zn-air battery,and exhibits satisfactory maximum power density,open-circuit voltage,and charge/discharge stability over benchmark Pt/C+IrO_(2).This work contributes new insights into the design of transition-metal-based multifunctional catalysts,and has great potential for energy conversion and storage.展开更多
The rational design of Ni-based catalysts is essential due to their abundance and low cost for advancing sustainable energy technologies,particularly for water splitting and fuel cells.This study employs spinpolarized...The rational design of Ni-based catalysts is essential due to their abundance and low cost for advancing sustainable energy technologies,particularly for water splitting and fuel cells.This study employs spinpolarized density functional theory(DFT)to examine the influence of anchoring rare-earth elements on the γ-NiOOH lattice surface,aiming to identify the optimal catalytic site for the oxygen evolution reaction(OER)and oxygen reduction reaction(ORR).Following the identification of an appropriate active site through Ni vacancy,a rare earth element(REE_(1))is introduced as a dopant for single-atom catalysis(SACs).The structural,thermodynamic,and catalytic characteristics of all newly designed REE_(1)/γ-NiOOH catalysts have been extensively studied.Among the newly developed catalysts,Tb_(1)/γ-NiOOH exhibits the lowest OER overpotential of(0.36 V),while Ce_(1)/γ-NiOOH and Pr_(1)/γ-NiOOH also demonstrate excellent OER performance(0.51 and 0.41 V),respectively.Notably,Nd_(1)/γ-NiOOH and Pm_(1)/γ-NiOOH exhibit efficient ORR activity,with low overpotentials of(0.63 and 0.61 V)due to their balanced adsorption and desorption energies of intermediates.Bader charge analysis reveals strong electron donation from doped REE1to the surface.This study identified Ce_(1),Pr_(1),Nd_(1),and Tb_(1) anchoring catalysts as highly promising for water-splitting applications.Moreover,Nd_(1) and Pm_(1) doping markedly improve ORR performance,underscoring their promise for enhanced electrochemical applications in metal-air batteries.The catalytic performance of all newly developed catalysts was further evaluated using electronic descriptors.The catalytic performance was further assessed using the volcano curve and scaling relationships for the adsorbed intermediates.This study offers an extensive theoretical foundation for designing cost-effective and high-performance REE_(1)/γ-NiOOH electrocatalysts.展开更多
Advancement of Co-N-C materials for efficient oxygen reduction reaction(ORR)is essential,given their potential as highly attractive alternatives to Pt-based catalysts.Here,we propose a novel strategy for the controlla...Advancement of Co-N-C materials for efficient oxygen reduction reaction(ORR)is essential,given their potential as highly attractive alternatives to Pt-based catalysts.Here,we propose a novel strategy for the controllable evolution of active Co sites via constructing a carbon substrate to fabricate a highperformance Co-N-C catalyst for ORR,which involves initiating a metallic Co phase adjacent to atomic Co sites to modify the electronic structures and promote synergistic effects.The resulting catalyst(CSDB-Co)demonstrates exceptional ORR activity(E_(1/2)=0.95 V vs.RHE)and zinc-air battery capability surpassing the benchmark catalysts in alkaline solutions.As evidenced by density functional theory(DFT)calculations,the remarkable ORR performance of C-SDB-Co originates from the synergy between the two Co phases that effectively regulates the electronic structure and lowers the energy barrier of intermediate adsorption.This study provides a new perspective on enhancing the catalytic activity of Co-N-C materials through innovative carbon substrate design and active site regulation.展开更多
Owing to their multi-elemental compositions and unique high-entropy mixing states,high-entropy alloy(HEA)nanoparticles(NPs)displaying tunable activities and enhanced stabilities thus have become a rapidly growing area...Owing to their multi-elemental compositions and unique high-entropy mixing states,high-entropy alloy(HEA)nanoparticles(NPs)displaying tunable activities and enhanced stabilities thus have become a rapidly growing area of research in recent years.However,the integration of multiple elements into HEA NPs at the nanoscale remains a formidable challenge,especially when it comes to the precise control of particle size,elemental composition and content.Herein,a simple and universal high-energy laser assisted reduction approach is presented,which achieves the preparation of HEA NPs with a wide range of multi-component,controllable particle sizes and constitution on different substrates within seconds.Laser on carbon nanofibers induced momentary high-temperature annealing(>2000 K and ramping/cooling rates>10^(5)K s^(-1))to successfully decorate HEA NPs up to twenty elements with excellent compatibility for large-scale synthesis(20.0×20.0 cm^(2)of carbon cloth).The IrPdPtRhRu exhibit robust electrocatalytic hydrogen evolution reaction(HER)activities and low overpotentials of 16,28,and 12 mV at a current density of 10 mA cm^(-2)in alkaline(1.0 M KOH),alkaline simulated seawater(1.0 M KOH+0.5 M NaCl),and acidic(0.5 M H_(2)SO_(4))electrolytes,respectively,and excellent stability(7 days and>2000 cycles)at the alkaline HER.展开更多
Mg-3Gd(wt.%)samples with different initial grain sizes were prepared to evaluate the grain size effect on microstructural evolution during cold rolling and subsequent annealing hardening response.The deformation behav...Mg-3Gd(wt.%)samples with different initial grain sizes were prepared to evaluate the grain size effect on microstructural evolution during cold rolling and subsequent annealing hardening response.The deformation behavior and mechanical response of the as-rolled and annealed samples were systematically investigated by a combination of electron microscopy and microhardness characterization.The results show that the twinning activities were highly suppressed in the fine-grained samples during rolling.Upon increasing the rolling reduction to 40%,ultra-fine grain structures with a volume fraction of∼28%were formed due to the activation of multiple slip systems.Conversely,twinning dominated the early stages of deformation in the coarse-grained samples.After a 10%rolling reduction,numerous twins with a volume fraction of∼23%were formed.Further increasing the rolling reduction to 40%,high-density dislocations were activated and twin structures with a volume fraction of∼36%were formed.The annealing hardening response of deformed samples was effectively enhanced compared to that of the non-deformed samples,which was attributed to the enhanced Gd segregation along grain boundaries,twin boundaries and dislocation cores.Moreover,the grain size and rolling reduction were found to affect the microstructure evolution during annealing,resulting in a notable difference in the annealing hardening response of Mg-3Gd alloy between samples of different grain sizes deformed to different strains.These findings highlight the crucial importance of microstructural and processing parameters in the design of high-strength,cost-effective Mg alloys.展开更多
The impact of rare-earth yttrium and cold-rolling reduction rate on the texture evolution and magnetic properties of non-oriented electrical steel is investigated.The experimental results clearly demonstrate that the ...The impact of rare-earth yttrium and cold-rolling reduction rate on the texture evolution and magnetic properties of non-oriented electrical steel is investigated.The experimental results clearly demonstrate that the influencing mechanism of rare-earth yttrium on texture evolution varies at different stages.During the stage of normalization and annealing,the second-phase particles with yttrium precipitate at the grain boundaries of brass-oriented grains,pinning the grain boundaries and inhibiting the development of brass components.During the cold rolling stage,the purification of rare earth yttrium significantly reduces the shear band density of cold-rolled steel.Consequently,the experimental steel with yttrium exhibits larger and more uniform grain size after recrystallization annealing.During the recrystallization stage,the nucleation energy of experimental steel with yttrium is reduced,which facilitates the nucleation of low-energy{100}and{110}grains,and greatly limits the growth of γ-recrystallized grains,forming strong cube and Goss textures after recrystallization annealing.The combination of these effects contributes to the superior magnetic properties of the non-oriented electrical steel with yttrium.The influence of cold rolling reduction rate on the magnetic properties of non-oriented silicon steel needs to be comprehensively considered in terms of the recrystallized grain size,texture,and sample thickness.The samples with higher cold-rolling reduction rate have better magnetic properties due to the reduction in eddy current losses caused by thickness reduction,which offsets the adverse effects of smaller grain size and more γ texture components on magnetic properties.展开更多
基金financially supported by the National Natural Science Foundation of China(52302084)the National Key Research and Development Program of China(2022YFE0138900)+1 种基金Fundamental Research Funds for the Central Universities(2232025D-24)the Qin Shen Scholar Program of Jiaxing University。
文摘The development of economical,highly efficient,and stable bifunctional electrocatalysts for both the oxygen evolution reaction(OER)and the oxygen reduction reaction(ORR)remains a critical focus in advancing rechargeable metal-air battery systems.Significant progress has been made in the design of high-performance bifunctional electrocatalysts,the development of novel oxygen electrode architectures,and the in-depth understanding of electrocatalytic mechanisms through combined experimental and computational studies.This work provides a comprehensive review of recent advancements in design strategies for oxygen catalysts,including homogeneous electrodes,asymmetric electrodes,and biomimetic electrodes,are thoroughly discussed and summarized.Then,the advanced catalyst modification strategies for ORR/OER are summarized,focusing on critical factors such as enhancement effect of metal/nonmental and synergistic enhancement effect in multiple catalyst.Subsequently,a representative performance evaluation is presented,based on the reported oxygen electrodes used in rechargeable metal-air battery applications.By focusing on these key areas,the review outlines the current challenges and future prospects for the development of bifunctional oxygen electrocatalysts,aiming to guide the design of high-performance bifunctional electrocatalysts and to elucidate the underlying mechanisms involved.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.22305071,52472200,52271176,and52072114)the 111 Project(Grant No.D17007)+3 种基金Henan Center for Outstanding Overseas Scientists(Grant No.GZS2022017)the China Postdoctoral Science Foundation(Grant No.2022M721049)the Henan Province Key Research and Development Project(Grant No.231111520500)the Natural Science Foundation of Henan Province(Grant No.252300421556)。
文摘Development of high-efficiency bifunctional oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)electrocatalysts is vital for the widespread application of zinc-air batteries(ZABs).However,it still remains a great challenge to avoid the inhomogeneous distribution and aggregation of metal single-atomic active centers in the construction of bifunctional electrocatalysts with atomically dispersed multimetallic sites because of the common calcination method.Herein,we report a novel catalyst with phthalocyanine-assembled Fe-Co-Ni single-atomic triple sites dispersed on sulfur-doped graphene using a simple ultrasonic procedure without calcination,and X-ray absorption fine structure(XAFS),aberration-corrected scanning transmission electron microscopy(AC-STEM),and other detailed characterizations are performed to demonstrate the successful synthesis.The novel catalyst shows extraordinary bifunctional ORR/OER activities with a fairly low potential difference(ΔE=0.621 V)between the OER overpotential(Ej10=315 mV at 10 m A cm^(-2))and the ORR half-wave potential(Ehalf-wave=0.924 V).Moreover,the above catalyst shows excellent ZAB performance,with an outstanding specific capacity(786 mAh g^(-1)),noteworthy maximum power density(139 mW cm^(-2)),and extraordinary rechargeability(discharged and charged at 5 mA cm^(-2) for more than 1000 h).Theoretical calculations reveal the vital importance of the preferable synergetic coupling effect between adjacent active sites in the Fe-Co-Ni trimetallic single-atomic sites during the ORR/OER processes.This study provides a new avenue for the investigation of bifunctional electrocatalysts with atomically dispersed trimetallic sites,which is intended for enhancing the ORR/OER performance in ZABs.
基金supported by the National Natural Science Foundation of China(Grant Nos.21433003,21805064 and 21773049)National Key Research and Development Program of China(Program No.2016YFB0101207)。
文摘ABO_(3)-type perovskite oxides(e.g.,LaCoO_(3))with flexible and adjustable A-and B-sites are ideal model catalysts to unravel the relationship between the electronic structure and electrocatalytic activity(e.g.,oxygen reduction/evolution reactions,ORR/OER).It has been well understood in our recent work that the secondary metal dopant at B-site(e.g.,Mn in LaMn_(x)Co_(1-x)O_(3))can regulate the electronic structure and improve the ORR/OER activity.In this work,the Mn-Ni pairs are employed as the dual dopant in LaMn_(x)Ni_(y)Co_(z)O_(3)(x+y+z=1)catalysts toward bifunctional ORR and OER.The structure-property relationships between the triple metal B-site(Mn,Ni and Co)and the electrochemical performance are particularly investigated.Compared to the individual Mn doping(e.g.,LaMnCoO3(Mn:Co=1:3)catalyst),the dual Mn-Ni doping significantly improves the ORR mass activity@0.8 V by 1.54 times;meanwhile,the OER overpotential@10 mA cm^(-2) is reduced from 420 to 370 mV,and the OER current density at 1.55 V is increased by 2.43 times.Reasonably,the potential gap between EDRR@-1 mA cm^(-2) and EDER@10 mA cm^(-2) is achieved as only 0.76 V by using the optimal LaMn_(x)Ni_(y)Co_(z)O_(3)(x:y:z=1:2:3)catalyst.It is revealed that the dual Mn-Ni dopant efficiently optimizes electron structures of the LaMnNiCoO_(3)(1:2:3)catalyst,which not only decreases the e_(g) orbital electron number,but also modulates the O 2 p-band closer to the Femi level,accounting for the enhanced bifunctional activity.
基金Funded by the National Natural Science Foundation of China Guangdong(No.22279096)。
文摘Silica nanoparticles-stabilized cobalt and nitrogen-doped carbon materials were synthesized through pyrolysis of metal-organic-framework of ZIF-67 supported by silica nanoparticles.The experimental results reveal that the introduction of the silica nanoparticles can stabilize the microstructure of the derived CoN-C materials,which in turn exhibits the promising electrocatalytic activity towards both oxygen reduction and oxygen evolution reactions.The optimized sample exhibits a better oxygen reduction activity than commercial Pt/C catalyst as confirmed by the positive shift of half-wave potential by 20 mV while it has a low overpotential of 273 mV for oxygen evolution reactions with the retained performance over 80%after 25,000 s of continuous operation.It is demonstrated that the introduction of support frame might be an effective way to improve the activity and stability of metal-organic-framework derived electrocatalyst with stabilized microstructure.
基金supported by the National Key Research&Development Program of China(No.2022YFC2904905)the National Natural Science Foundation of China(No.52274400)+1 种基金the Project of Zhongyuan Critical Metals Laboratory,China(No.GJJSGFZD202302)the Science and Technology Project of Henan Province,China(No.232102230044)。
文摘The hydrogen reduction kinetics of tungsten trioxide(WO_(3))was investigated via non-isothermal thermogravimetric analysis.Under the local gas-solid reduction conditions,the particle morphology of tungsten powders was found to be consistent with that of raw material WO_(3).The removal of oxygen from tungsten oxide during hydrogen reduction led to the formation of porous structures between the reduced particles,which were obviously different from the polyhedral single-crystal configuration of tungsten powders obtained via chemical vapor deposition.Moreover,the two-stage hydrogen reduction mechanisms of WO_(3) under the local gas-solid reduction conditions can be described using the composite autocatalytic function.The activation energies of the first and second stages of the hydrogen reduction of WO_(3) were determined to be 121 and 135 kJ/mol,respectively.
基金financial support of the National Natural Science Foundation of China(NSFC)(52394202,52021004,52301232,and 52476056)the Natural Science Foundation of Chongqing Province(2024NSCQ-MSX1109).
文摘The scaling-up of electrochemical CO_(2)reduction requires circumventing the CO_(2)loss as carbonates under alkaline conditions.Zero-gap MEA cell configurations with a proton exchange membrane represent an alternative solution in a pure acidic system,but the catalyst layer in direct contact with the hydrated proton environment usually leads to H_(2)evolution dominating.Herein,we show that polydimethyldiallyl-ammonium-chloride-coated Ag(Ag@PDDA)electrode exhibits outstanding performance with a FE of 86%,a single-pass conversion of 72%,and a stability of 28 h for CO production in pure-acid MEA compared with ammonium poly(N-methyl-piperidine-co-pterphenyl)decorated Ag(Ag/QAPPT)and cetyltrimethylammonium bromide decorated Ag(Ag/CTAB).The in situ ATR-SEIRAS reveal that PDDA creates a positive charge-rich protective outer layer and an N-rich hybrid inner layer,which not only suppresses the migration of H+during the electrolysis process and blocks the direct contact between H2O and Ag catalyst,but also promotes the generation from CO_(2)to*COOH in a pure-acid system.This work highlights the importance of polyelectrolyte engineering in regulating the electrocatalytic interface and accelerates the development of proton exchange membrane CO_(2)electrolysis.
基金supported by MOST(no.2017YFA0206700)NSFC(no.21231005)MOE(no.B12015 and IRT13R30).
文摘We report an in situ preparation of ultrasmall Co–Mn–O spinel nanoparticles(4.4 nm)supported on nonoxidized carbon nanotubes(denoted as CMO@CNTs)as a bifunctional catalyst for oxygen reduction and evolution reactions(ORR/OER).The preparation process involves the oxidization of divalent metal ions under alkaline conditions and the decomposition of nitrates in aqueous solution containing dispersed non-oxidized CNTs.The synthesized CMO nanoparticles strongly couple with the non-oxidized CNTs,which facilitates electron transfer and improves the catalytic activity.Other composites such as CMO@reduced graphene oxide,CMO@Vulcan X-72R,CMO@oxidized CNTs,and a physical mixture of CMO and CNTs were also prepared for comparison.Remarkably,CMO@CNTs exhibit a half wave potential of 0.91 V in 1 M KOH and higher kinetic current and better catalytic durability than Pt/C.Moreover,CMO@CNTs afford an electrocatalytic OER current density of 10 mA cm^(−2) at a low potential of 1.5 V and a small Tafel slope of 81.1 mV dec^(−1).Furthermore,CMO@CNTs display lower discharge/charge overpotential and more stable voltage plateau on cycling than that of Pt/C when employed as a cathode material in rechargeable Zn–air cells.This work indicates that CMO@CNTs are a promising,cheap and efficient bifunctional ORR/OER electrocatalyst for rechargeable metal–air batteries.
基金supported by the National Natural Science Foundation of China(Nos.22271007,W2431014)Peking University Shenzhen Graduate School+2 种基金State Key Laboratory of Chemical OncogenomicsShenzhen Key Laboratory of Chemical GenomicsShenzhen Bay Laboratory.
文摘Chiral benzylic amines are important motifs in medicines.A dicationic nickel complex of chiral diphosphine(R)-Ph-BPE promotes highly enantioselective reductive amination of aryl alkyl ketones with arylamines using isopropanol as hydrogen source.The reaction is easily scaled up in a gram-scale synthesis using 1 mol% nickel catalyst and it is applied to an asymmetric synthesis of(S)-rivastigmine.Building on this success,we achieved rare examples of asymmetric hydrogen borrowing reactions with arylamines using an Earth-abundant 3d metal,nickel.
基金support of the National Natural Science Foundation of China(52074080,52004001,and 51574002).
文摘Against the background of“carbon peak and carbon neutrality,”it is of great practical significance to develop non-blast furnace ironmaking technology for the sustainable development of steel industry.Carbon-bearing iron ore pellet is an innovative burden of direct reduction ironmaking due to its excellent self-reducing property,and the thermal strength of pellet is a crucial metallurgical property that affects its wide application.The carbon-bearing iron ore pellet without binders(CIPWB)was prepared using iron concentrate and anthracite,and the effects of reducing agent addition amount,size of pellet,reduction temperature and time on the thermal compressive strength of CIPWB during the reduction process were studied.Simultaneously,the mechanism of the thermal strength evolution of CIPWB was revealed.The results showed that during the low-temperature reduction process(300-500℃),the thermal compressive strength of CIPWB linearly increases with increasing the size of pellet,while it gradually decreases with increasing the anthracite ratio.When the CIPWB with 8%anthracite is reduced at 300℃for 60 min,the thermal strength of pellet is enhanced from 13.24 to 31.88 N as the size of pellet increases from 8.04 to 12.78 mm.Meanwhile,as the temperature is 500℃,with increasing the anthracite ratio from 2%to 8%,the thermal compressive strength of pellet under reduction for 60 min remarkably decreases from 41.47 to 8.94 N.Furthermore,in the high-temperature reduction process(600-1150℃),the thermal compressive strength of CIPWB firstly increases and then reduces with increasing the temperature,while it as well as the temperature corresponding to the maximum strength decreases with increasing the anthracite ratio.With adding 18%anthracite,the thermal compressive strength of pellet reaches the maximum value at 800℃,namely 35.00 N,and obtains the minimum value at 1050℃,namely 8.60 N.The thermal compressive strength of CIPWB significantly depends on the temperature,reducing agent dosage,and pellet size.
文摘Hydrogen evolution reaction(HER)is unavoidable in many electrochemical synthesis systems,such as CO_(2)reduction,N2reduction,and H_(2)O_(2)synthesis.It makes those electrochemical reactions with multiple electron-proton transfers more complex when determining kinetics and mass transfer information.Understanding how HER competes with other electrochemical reduction reactions is crucial for both fundamental studies and system performance improvements.In this study,we employed the oxygen reduction reaction(ORR)as a model reaction to investigate HER competition on a polycrystalline-Au surface,using a rotating ring and disk electrode.It’s proved that water molecules serve as the proton source for ORR in alkaline,neutral,and even acidic electrolytes,and a 4-electron process can be achieved when the overpotential is sufficiently high.The competition from H⁺reduction becomes noticeable at the H⁺concentration higher than 2 mmol L^(–1)and intensi-fies as the H^(+)concentration increases.Based on the electrochemical results,we obtained an equivalent circuit diagram for the ORR system with competition from the H+reduction reaction,showing that these reactions occur in parallel and compete with each other.Electrochemical impedance spectroscopy measurements further confirm this argument.Additionally,we discover that the contribution of H+mass transfer to the total H^(+)reduction current is significant and comparable to the kinetic current.We believe this work will deepen our understanding of HER and its competition in electrochemical reduction systems.
基金supported by the National Natural Science Foundation of China(21832005,22072168,22002175)Major Program of the Lanzhou Institute of Chemical Physics,CAS(No.ZYFZFX-3)+1 种基金Major Science and Technology Projects in Gansu Province(22ZD6GA003)West Light Foundation of The Chinese Academy of Sciences(xbzg-zdsys-202209).
文摘Artificial carbon fixation is a promising pathway for achieving the carbon cycle and environment remediation.However,the sluggish kinetics of oxygen evolution reaction(OER)and poor selectivity of CO_(2) reduction seriously limited the overall conversion efficiencies of solar energy to chemical fuels.Herein,we demonstrated a facile and feasible strategy to rationally regulate the coordination environment and electronic structure of surface-active sites on both photoanode and cathode.More specifically,the defect engineering has been employed to reduce the coordination number of ultrathin FeNi catalysts decorated on BiVO4 photoanodes,resulting in one of the highest OER activities of 6.51 mA cm^(−2)(1.23 VRHE,AM 1.5G).Additionally,single-atom cobalt(II)phthalocyanine anchoring on the N-rich carbon substrates to increase Co–N coordination number remarkably promotes CO_(2) adsorption and activation for high selective CO production.Their integration achieved a record activity of 109.4μmol cm^(−2) h−1 for CO production with a faradaic efficiency of>90%,and an outstanding solar conversion efficiency of 5.41%has been achieved by further integrating a photovoltaic utilizing the sunlight(>500 nm).
基金financially supported by the National Natural Science Foundation of China(Nos.62264015 and U2233206)the Civil Aviation Administration of China(No.U1933109)Hubei Province Technology Innovation Program Project(No.2024BCB073)
文摘Inspired by hexaazanaphthalene-based conjugated copper metal-organic framework(HATNA-Cu-MOF),we designed 161 HATNA-TM-MOF-based SACs(TM@N_(x)O_(4-x)-HATNA)with varying TM or ligands creating distinct coordination environments(x=0-4)with superior thermodynamic and electrochemical stabilities.Volcano plots can be constructed using(AGOOH^(*)-ΔGO^(*))/ΔGO^(*)as descriptors for oxygen evolution/reduction reaction(OER/ORR)activity,also serving as target parameters for machine learning(ML)models to identify high-performance OER/ORR catalysts.The efficient monofunctional and bifunctional electrocatalysts were successfully predicted,where the ML prediction results well matched the DFT calculation results.We employed Shapley additive explanations(SHAP)for feature analysis and utilized sure independence screening and sparsification operator(SISSO)for generalization.ML analyses reveal that TM-based OER/ORR activities predominantly correlate with three key descriptors:metallic atomic radius,d-orbital electron population,and the heat of formation of the oxide,demonstrating the pivotal role of TM's inherent electronic configuration and physicochemical characteristics in governing electrocatalytic efficacy.The constant-potential approach emphasizes the key role of electric double-layer capacitance in adjusting the kinetic barrier,where changes in the Fermi level influence the occupation of d-orbitals.Variations in electrochemical potential significantly alter the electronic structure of representative Rh@N_(1)O_(3)-HATNA,affecting both the Fermi level and adsorption properties,with the unique 4d^(8)5s^(1)configuration leading to inverted O_(2)adsorption energies as the potential decreases.This study contributes insights into the origin of oxygen evolution-reduction activity for the HATNA-TM-MOF-based SACs and reveals the fundamentals of structure-activity relationships for future applications.
基金financially supported by the National Natural Science Foundation of China(22478432,22108306,22178388)Taishan Scholars Program of Shandong Province(tsqn201909065)+2 种基金Shandong Provincial Natural Science Foundation(ZR2024JQ004)Innovation Fund Project for Graduate Student of China University of Petroleum(East China)the Fundamental Research Funds for the Central Universities(No.25CX04020A)。
文摘The development of single atom catalysts(SACs)with asymmetric active sites by defect regulation provides an encourage potential for oxygen reduction reaction(ORR)and hydrogen evolution reaction(HER),but highly challenging.Herein,N-doped carbon(N-C)anchored atomically dispersed Ni-N_(3)site with proximity defects(Ni-N_(3)D)induced by Te atoms doping is reported.Benefitting from the inductive effect of proximity defect,the Ni-N_(3)D/Te-N-C catalyst performs excellent ORR and HER performance in alkaline and acid condition.Both in situ characterization and theoretical calculation reveal that the existence of proximity defect effect is conducive to lower rate-determining-step energy barrier of ORR and HER,thus accelerating the multielectron reaction kinetics.This work paves a novel strategy for constructing highactivity bifunctional SACs by defect engineering for development of sustainable energy.
基金supported by the National Natural Science Foundation of China(Nos.22078118 and 42277219)the Natural Science Foundation of Guangdong Province,China(No.2023A1515010740).
文摘A novel photocatalytic cocatalyst, MoC quantum dots integrated into N-doped carbon microflowers (MoC–NC), was synthesized, establishing a key Mo–N interfacial bond. The Mo–N bond's regulation was achieved by adjusting the pH of Mo-polydopamine precursor solutions. A composite photocatalyst, MoC–NC/CdS (MNS), was formed by in situ growth of nano-CdS on MoC–NC. The pH during synthesis, crucial for Mo–N bond formation, significantly influenced Cr(Ⅵ) reduction and H_(2) evolution performance. The optimal MNS, created at pH 9.0, demonstrated 99.2% reduction efficiency for Cr(Ⅵ) in 20 min and H_(2) evolution rate of 11.4 mmol g^(-1) h^(-1) over 3 h, outperforming Pt/CdS. Mechanistic studies and density functional theory revealed MoC–NC's role in enhancing light absorption, reaction kinetics, and electron transport, attributing to its ultra-small quantum dots and abundant Mo–N bonds.
基金financially supported by the National Natural Science Foundation of China(51902149,51674131,22305108)the Fundamental Research Funds for Public Universities in Liaoning(LJ232410140033)the Scientific Research Funding of the Education Department of Liaoning Province(JYTZD2023070,LJKFZ20220180,LJKMZ20220453)。
文摘Optimizing active sites and enhancing mass transfer capability are of paramount importance for the improvement of electrocatalyst activity.On this basis,CoFe_(2)O_(4)/CoFe nanoparticles(NPs)loaded N-doped carbon(NC)that featured with interconnected three-dimensional(3D)ordered porous hierarchies(3DOM FeCo/NC)are prepared,and its electrocatalytic activity is studied.Due to the open structure of 3D ordered macro-pores that greatly improves the mass transfer capacity of the catalytic process and enhances the utilization of active sites inside the catalyst,as well as the uniform distribution of Fe and Co bimetallic sites on the porous skeleton,3DOM FeCo/NC exhibits superior bi-functional catalytic activities for both hydrogen evolution reaction(HER)and oxygen reduction reaction(ORR).The overpotential of HER is lower than that of commercial Pt/C when performed at high current density(>235 mA cm^(-2))in1.0 M KOH,and the half-wave potential(0.896 V)of ORR in 0.1 M KOH is also superior to that of 20% commercial Pt/C and most other similar catalysts.The effective utilization and synergistic effect of CoFe_(2)O_(4)and CoFe hetero-metallic sites remarkably enhance the electrocatalytic activity.Furthermore,3DOM FeCo/NC is assembled as an air electrode in Zn-air battery,and exhibits satisfactory maximum power density,open-circuit voltage,and charge/discharge stability over benchmark Pt/C+IrO_(2).This work contributes new insights into the design of transition-metal-based multifunctional catalysts,and has great potential for energy conversion and storage.
基金supported by the BRICS STI Framework Programme(No.52261145703)the Higher Education Discipline Innovation Project(National 111 Project,No.B16016)。
文摘The rational design of Ni-based catalysts is essential due to their abundance and low cost for advancing sustainable energy technologies,particularly for water splitting and fuel cells.This study employs spinpolarized density functional theory(DFT)to examine the influence of anchoring rare-earth elements on the γ-NiOOH lattice surface,aiming to identify the optimal catalytic site for the oxygen evolution reaction(OER)and oxygen reduction reaction(ORR).Following the identification of an appropriate active site through Ni vacancy,a rare earth element(REE_(1))is introduced as a dopant for single-atom catalysis(SACs).The structural,thermodynamic,and catalytic characteristics of all newly designed REE_(1)/γ-NiOOH catalysts have been extensively studied.Among the newly developed catalysts,Tb_(1)/γ-NiOOH exhibits the lowest OER overpotential of(0.36 V),while Ce_(1)/γ-NiOOH and Pr_(1)/γ-NiOOH also demonstrate excellent OER performance(0.51 and 0.41 V),respectively.Notably,Nd_(1)/γ-NiOOH and Pm_(1)/γ-NiOOH exhibit efficient ORR activity,with low overpotentials of(0.63 and 0.61 V)due to their balanced adsorption and desorption energies of intermediates.Bader charge analysis reveals strong electron donation from doped REE1to the surface.This study identified Ce_(1),Pr_(1),Nd_(1),and Tb_(1) anchoring catalysts as highly promising for water-splitting applications.Moreover,Nd_(1) and Pm_(1) doping markedly improve ORR performance,underscoring their promise for enhanced electrochemical applications in metal-air batteries.The catalytic performance of all newly developed catalysts was further evaluated using electronic descriptors.The catalytic performance was further assessed using the volcano curve and scaling relationships for the adsorbed intermediates.This study offers an extensive theoretical foundation for designing cost-effective and high-performance REE_(1)/γ-NiOOH electrocatalysts.
基金finacially supported by National Natural Sci-ence Foundation of China(Nos.22275210,22171288)Natural Sci-ence Foundation of Shandong Province(No.ZR2022MB009)+1 种基金Out-standing Youth Science Fund Projects of Shandong Province(No.ZR2022YQ15)Fundamental Research Funds for the Central Universities(No.YCX2021142).
文摘Advancement of Co-N-C materials for efficient oxygen reduction reaction(ORR)is essential,given their potential as highly attractive alternatives to Pt-based catalysts.Here,we propose a novel strategy for the controllable evolution of active Co sites via constructing a carbon substrate to fabricate a highperformance Co-N-C catalyst for ORR,which involves initiating a metallic Co phase adjacent to atomic Co sites to modify the electronic structures and promote synergistic effects.The resulting catalyst(CSDB-Co)demonstrates exceptional ORR activity(E_(1/2)=0.95 V vs.RHE)and zinc-air battery capability surpassing the benchmark catalysts in alkaline solutions.As evidenced by density functional theory(DFT)calculations,the remarkable ORR performance of C-SDB-Co originates from the synergy between the two Co phases that effectively regulates the electronic structure and lowers the energy barrier of intermediate adsorption.This study provides a new perspective on enhancing the catalytic activity of Co-N-C materials through innovative carbon substrate design and active site regulation.
基金supported by the National Natural Science Foundation of China(Grant No.52072274 and 52104309)the Knowledge Innovation Project of Wuhan,China(2023020201010131).
文摘Owing to their multi-elemental compositions and unique high-entropy mixing states,high-entropy alloy(HEA)nanoparticles(NPs)displaying tunable activities and enhanced stabilities thus have become a rapidly growing area of research in recent years.However,the integration of multiple elements into HEA NPs at the nanoscale remains a formidable challenge,especially when it comes to the precise control of particle size,elemental composition and content.Herein,a simple and universal high-energy laser assisted reduction approach is presented,which achieves the preparation of HEA NPs with a wide range of multi-component,controllable particle sizes and constitution on different substrates within seconds.Laser on carbon nanofibers induced momentary high-temperature annealing(>2000 K and ramping/cooling rates>10^(5)K s^(-1))to successfully decorate HEA NPs up to twenty elements with excellent compatibility for large-scale synthesis(20.0×20.0 cm^(2)of carbon cloth).The IrPdPtRhRu exhibit robust electrocatalytic hydrogen evolution reaction(HER)activities and low overpotentials of 16,28,and 12 mV at a current density of 10 mA cm^(-2)in alkaline(1.0 M KOH),alkaline simulated seawater(1.0 M KOH+0.5 M NaCl),and acidic(0.5 M H_(2)SO_(4))electrolytes,respectively,and excellent stability(7 days and>2000 cycles)at the alkaline HER.
基金financial support from the National Key Research and Development Program of China(No.2021YFB3702101)National Natural Science Foundation of China(No.52130107,52071038)+5 种基金Fundamental Research Funds for the Central Universities(No.2023CDJXY-018)the“111”Project(No.B16007)by the Ministry of Education and the State Administration of Foreign Experts Affairs of Chinasupport to the Norwegian Micro-and Nano-Fabrication Facility,NorFab(No.295864)the Norwegian Laboratory for Mineral and Materials Characterization,MiMaC(No.269842/F50)the RCN INRPART project IntMat(No.309724)the Center for Research based Innovation SFI PhysMet(No.309584).
文摘Mg-3Gd(wt.%)samples with different initial grain sizes were prepared to evaluate the grain size effect on microstructural evolution during cold rolling and subsequent annealing hardening response.The deformation behavior and mechanical response of the as-rolled and annealed samples were systematically investigated by a combination of electron microscopy and microhardness characterization.The results show that the twinning activities were highly suppressed in the fine-grained samples during rolling.Upon increasing the rolling reduction to 40%,ultra-fine grain structures with a volume fraction of∼28%were formed due to the activation of multiple slip systems.Conversely,twinning dominated the early stages of deformation in the coarse-grained samples.After a 10%rolling reduction,numerous twins with a volume fraction of∼23%were formed.Further increasing the rolling reduction to 40%,high-density dislocations were activated and twin structures with a volume fraction of∼36%were formed.The annealing hardening response of deformed samples was effectively enhanced compared to that of the non-deformed samples,which was attributed to the enhanced Gd segregation along grain boundaries,twin boundaries and dislocation cores.Moreover,the grain size and rolling reduction were found to affect the microstructure evolution during annealing,resulting in a notable difference in the annealing hardening response of Mg-3Gd alloy between samples of different grain sizes deformed to different strains.These findings highlight the crucial importance of microstructural and processing parameters in the design of high-strength,cost-effective Mg alloys.
基金supported by the 2024 Fundamental Research Project(No.LJ212410154007)of the Educational Department of Liaoning Province.
文摘The impact of rare-earth yttrium and cold-rolling reduction rate on the texture evolution and magnetic properties of non-oriented electrical steel is investigated.The experimental results clearly demonstrate that the influencing mechanism of rare-earth yttrium on texture evolution varies at different stages.During the stage of normalization and annealing,the second-phase particles with yttrium precipitate at the grain boundaries of brass-oriented grains,pinning the grain boundaries and inhibiting the development of brass components.During the cold rolling stage,the purification of rare earth yttrium significantly reduces the shear band density of cold-rolled steel.Consequently,the experimental steel with yttrium exhibits larger and more uniform grain size after recrystallization annealing.During the recrystallization stage,the nucleation energy of experimental steel with yttrium is reduced,which facilitates the nucleation of low-energy{100}and{110}grains,and greatly limits the growth of γ-recrystallized grains,forming strong cube and Goss textures after recrystallization annealing.The combination of these effects contributes to the superior magnetic properties of the non-oriented electrical steel with yttrium.The influence of cold rolling reduction rate on the magnetic properties of non-oriented silicon steel needs to be comprehensively considered in terms of the recrystallized grain size,texture,and sample thickness.The samples with higher cold-rolling reduction rate have better magnetic properties due to the reduction in eddy current losses caused by thickness reduction,which offsets the adverse effects of smaller grain size and more γ texture components on magnetic properties.
