Electrochemical water splitting is regarded as the most promising approach to produce hydrogen.However,the sluggish electrochemical reactions occurring at the anode and cathode,namely,the oxygen evolution reaction(OER...Electrochemical water splitting is regarded as the most promising approach to produce hydrogen.However,the sluggish electrochemical reactions occurring at the anode and cathode,namely,the oxygen evolution reaction(OER)and the hydrogen evolution reaction(HER),respectively,consume a tremendous amount of energy,seriously hampering its wide application.Recently,single-atom catalysts(SACs)have been proposed to effectively enhance the kinetics of these two reactions.In this minireview,we focus on the recent progress in SACs for OER and HER applications.Three classes of SACs have been reviewed,i.e.,alloy-based SACs,carbon-based SACs and SACs supported on other compounds.Different factors affecting the activities of SACs are also highlighted,including the inherent element property,the coordination environment,the geometric structure and the loading amount of metal atoms.Finally,we summarize the current problems and directions for future development in SACs.展开更多
Nanostructured scaffolds offer promising opportunities in enabling dendrite-free long-cycle life Li metal anode.The rational design and controllable synthesis of scaffolding architectures are imperative for developmen...Nanostructured scaffolds offer promising opportunities in enabling dendrite-free long-cycle life Li metal anode.The rational design and controllable synthesis of scaffolding architectures are imperative for development of rechargeable Li metal batteries.In this study,we explore the fabrication and application of a tin monoxide/graphene hybrid architecture as a lithiophilic host for high-performance Li metal anode.Using a polymer-assisted sonochemical synthesis route,we tuned the thickness of SnO nanolayers and the nanostructure of alternatively stacking thin SnO nanosheet/graphene(SnO-NS/G) heterostructure.Offering abundant nucleation sites,fast ion transport tunnels,and 3D-conductivity,the unique 2D-2D architecture enables stable lithium plating-stripping cycling with low nucleation overpotential and high coulombic efficiency(CE).Hosted by SnO-NS/G scaffold,the resulting Li metal anode exhibits stable cycling over 200 cycles at 0.5 mA cm^(-2)(2 mAh).Full cell pairing high-mass-loading cathode LiCoO_(2)(LCO)(12 mg cm^(-2)) with SnO-NS/G hosted Li metal anode delivers high energy density of 402 Wh kg^(-1) and stable cyclability of over 100 cycles.We elucidate the structure-property relationship between nanolayer thickness and Li-metal plating behaviors,giving new insight on structuring 2D-nanomaterials with ideal architectures for stable lithium metal batteries.展开更多
Elucidation the relationship between electrode potentials and heterogeneous electrocatalytic reactions has attracted widespread attention.Herein we construct the well-defined Mn single-atom(MnSA)catalyst with four N-c...Elucidation the relationship between electrode potentials and heterogeneous electrocatalytic reactions has attracted widespread attention.Herein we construct the well-defined Mn single-atom(MnSA)catalyst with four N-coordination through a simple thermal pyrolysis preparation method to investigate the electrode potential micro-environments effect on carbon dioxide reduction reactions(CO_(2)RR)and oxygen reduction reactions(ORR).MnSA catalysts generate higher CO production Faradaic efficiency of exceeding 90%at-0.9 V for CO_(2)RR and higher H_(2)O_(2)yield from 0.1 to 0.6 V with excellent ORR activity.Density functional theory(DFT)calculations based on constant potential models were performed to study the mechanism of MnSA on CO_(2)RR.The thermodynamic energy barrier of CO_(2)RR is lowest at-0.9 V vs.reversible hydrogen electrode(RHE).Similar DFT calculations on the H_(2)O_(2)yield of ORR showed that the H_(2)O_(2)yield at 0.2 V was higher.This study provides a reasonable explanation for the role of electrode potential micro-environments.展开更多
Metal-nitrogen doped carbon catalysts(M-N/C) with abundantly accessible M-Nxsites, particularly single metal atom M-N/C(SAM-N/C), have been developed as a substitute for expensive Pt-based catalysts.These catalysts ar...Metal-nitrogen doped carbon catalysts(M-N/C) with abundantly accessible M-Nxsites, particularly single metal atom M-N/C(SAM-N/C), have been developed as a substitute for expensive Pt-based catalysts.These catalysts are used to increase the efficiency of otherwise sluggish oxygen reduction reactions(ORR) and hydrogen evolution reactions(HER). However, although the agglomerated metal nanoparticles are usually easy to form, they are very difficult to remove due to the protective surface-coating carbon layers, a factor that significantly hampers SAM-N/C fabrication. Herein, we report a one-step pyrolysis approach to successfully fabricate single cobalt atom Co-N/C(SACo-N/C) by using a Co2+-SCN-coordination compound as the metal precursor. Thanks to the decomposition of Co2+-SCN-compound at lower temperature than that of carbon layer deposition, Co-rich particles grow up to larger ones before carbon layers formation. Even though encapsulated by the carbon layers, it is difficult for the large Co-rich particle to be completely sealed. And thus, it makes the Co atoms possible to escape from incomplete carbon layer, to coordinate with nitrogen atoms, and to form SACo-N/C catalysts. This SACo-N/C exhibits excellent performances for both ORR(half-wave potential of 0.878 V) and HER(overpotential at 10 mA/cm2 of178 m V), and is thus a potential replacement for Pt-based catalysts. When SACo-N/C is integrated into a Zn-O2 battery, battery with high open-circuit voltage(1.536 V) has high peak power density(266 mW/cm2)and large gravimetric energy density(755 mA h/gZn) at current densities of 100 mA/cm2. Thus, we believe that this strategy may offer a new direction for the effective generation of SAM-N/C catalysts.展开更多
文摘Electrochemical water splitting is regarded as the most promising approach to produce hydrogen.However,the sluggish electrochemical reactions occurring at the anode and cathode,namely,the oxygen evolution reaction(OER)and the hydrogen evolution reaction(HER),respectively,consume a tremendous amount of energy,seriously hampering its wide application.Recently,single-atom catalysts(SACs)have been proposed to effectively enhance the kinetics of these two reactions.In this minireview,we focus on the recent progress in SACs for OER and HER applications.Three classes of SACs have been reviewed,i.e.,alloy-based SACs,carbon-based SACs and SACs supported on other compounds.Different factors affecting the activities of SACs are also highlighted,including the inherent element property,the coordination environment,the geometric structure and the loading amount of metal atoms.Finally,we summarize the current problems and directions for future development in SACs.
基金supported by the National Natural Science Foundation of China(51702223)International Collaborative Project of Chengdu(2019-GH02-00031-HZ)China Postdoctoral Science Foundation(2019T120839)。
文摘Nanostructured scaffolds offer promising opportunities in enabling dendrite-free long-cycle life Li metal anode.The rational design and controllable synthesis of scaffolding architectures are imperative for development of rechargeable Li metal batteries.In this study,we explore the fabrication and application of a tin monoxide/graphene hybrid architecture as a lithiophilic host for high-performance Li metal anode.Using a polymer-assisted sonochemical synthesis route,we tuned the thickness of SnO nanolayers and the nanostructure of alternatively stacking thin SnO nanosheet/graphene(SnO-NS/G) heterostructure.Offering abundant nucleation sites,fast ion transport tunnels,and 3D-conductivity,the unique 2D-2D architecture enables stable lithium plating-stripping cycling with low nucleation overpotential and high coulombic efficiency(CE).Hosted by SnO-NS/G scaffold,the resulting Li metal anode exhibits stable cycling over 200 cycles at 0.5 mA cm^(-2)(2 mAh).Full cell pairing high-mass-loading cathode LiCoO_(2)(LCO)(12 mg cm^(-2)) with SnO-NS/G hosted Li metal anode delivers high energy density of 402 Wh kg^(-1) and stable cyclability of over 100 cycles.We elucidate the structure-property relationship between nanolayer thickness and Li-metal plating behaviors,giving new insight on structuring 2D-nanomaterials with ideal architectures for stable lithium metal batteries.
基金supported by the National Natural Science Foundation of China(Nos.52073214 and 22075211)Guangxi Natural Science Fund for Distinguished Young Scholars(No.2024GXNSFFA010008).
文摘Elucidation the relationship between electrode potentials and heterogeneous electrocatalytic reactions has attracted widespread attention.Herein we construct the well-defined Mn single-atom(MnSA)catalyst with four N-coordination through a simple thermal pyrolysis preparation method to investigate the electrode potential micro-environments effect on carbon dioxide reduction reactions(CO_(2)RR)and oxygen reduction reactions(ORR).MnSA catalysts generate higher CO production Faradaic efficiency of exceeding 90%at-0.9 V for CO_(2)RR and higher H_(2)O_(2)yield from 0.1 to 0.6 V with excellent ORR activity.Density functional theory(DFT)calculations based on constant potential models were performed to study the mechanism of MnSA on CO_(2)RR.The thermodynamic energy barrier of CO_(2)RR is lowest at-0.9 V vs.reversible hydrogen electrode(RHE).Similar DFT calculations on the H_(2)O_(2)yield of ORR showed that the H_(2)O_(2)yield at 0.2 V was higher.This study provides a reasonable explanation for the role of electrode potential micro-environments.
基金supported by the National Key Research and Development Program of China(2016YFB0101202)the National Natural Science Foundation of China(21761162015,91534205,21436003)the Fundamental Research Funds for the Central Universities
文摘Metal-nitrogen doped carbon catalysts(M-N/C) with abundantly accessible M-Nxsites, particularly single metal atom M-N/C(SAM-N/C), have been developed as a substitute for expensive Pt-based catalysts.These catalysts are used to increase the efficiency of otherwise sluggish oxygen reduction reactions(ORR) and hydrogen evolution reactions(HER). However, although the agglomerated metal nanoparticles are usually easy to form, they are very difficult to remove due to the protective surface-coating carbon layers, a factor that significantly hampers SAM-N/C fabrication. Herein, we report a one-step pyrolysis approach to successfully fabricate single cobalt atom Co-N/C(SACo-N/C) by using a Co2+-SCN-coordination compound as the metal precursor. Thanks to the decomposition of Co2+-SCN-compound at lower temperature than that of carbon layer deposition, Co-rich particles grow up to larger ones before carbon layers formation. Even though encapsulated by the carbon layers, it is difficult for the large Co-rich particle to be completely sealed. And thus, it makes the Co atoms possible to escape from incomplete carbon layer, to coordinate with nitrogen atoms, and to form SACo-N/C catalysts. This SACo-N/C exhibits excellent performances for both ORR(half-wave potential of 0.878 V) and HER(overpotential at 10 mA/cm2 of178 m V), and is thus a potential replacement for Pt-based catalysts. When SACo-N/C is integrated into a Zn-O2 battery, battery with high open-circuit voltage(1.536 V) has high peak power density(266 mW/cm2)and large gravimetric energy density(755 mA h/gZn) at current densities of 100 mA/cm2. Thus, we believe that this strategy may offer a new direction for the effective generation of SAM-N/C catalysts.
