Single atom catalysts(SACs)with atomically dispersed transition metals on nitrogen-doped carbon supports have recently emerged as highly active non-noble metal electrocatalysts for oxygen reduction reaction(ORR)and ox...Single atom catalysts(SACs)with atomically dispersed transition metals on nitrogen-doped carbon supports have recently emerged as highly active non-noble metal electrocatalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),showing great application potential in Zn-air batteries.However,because of the complex structure-performance relationships of carbon-based SACs in the oxygen electrocatalytic reactions,the contribution of different metal atoms to the catalytic activity of SACs in Zn-air batteries still remains ambiguous.In this study,SACs with atomically dispersed transition metals on nitrogen-doped graphene sheets(M-N@Gs,M=Co,Fe and Ni),featured with similar physicochemical properties and M-N@C configurations,are obtained.By comparing the on-set potentials and the maximum current,we observed that the ORR activity is in the order of Co-N@G>Fe-N@G>Ni-N@G,while the OER activity is in the order of Co-N@G>Ni-N@G>Fe-N@G.The Zn-air batteries with Co-N@G as the air cathode catalysts outperform those with the Fe-N@G and Ni-N@G.This is due to the accelerated charge transfer between Co-N@C active sites and the oxygen-containing reactants.This study could improve our understanding of the design of more efficient bifunctional electrocatalysts for Zn-air batteries at the atomic level.展开更多
Sulfur redox reactions render lithium–sulfur(Li–S)batteries with an energy density of>500Whkg−1 but suffer a low practical capacity and fast capacity fade due to sluggish sulfur redox reaction(SRR)kinetics,which ...Sulfur redox reactions render lithium–sulfur(Li–S)batteries with an energy density of>500Whkg−1 but suffer a low practical capacity and fast capacity fade due to sluggish sulfur redox reaction(SRR)kinetics,which lies in the complex reaction process that involves a series of reaction intermediates and proceeds via a cascade reaction.Here,we present a Pt–Cu dual-atom catalyst(Pt/Cu-NG)as an electrocatalyst for sulfur redox reactions.Pt/Cu-NG enabled the rapid conversion of soluble polysulfide intermediates into insoluble Li2S2/Li2S,and consequently,it prevented the accumulation and shuttling of lithium polysulfides,thus outperforming the corresponding single-atom catalysts(SACs)with individual Pt or Cu sites.Operando X-ray absorption spectroscopy and density functional theory calculations revealed that a synergistic effect between the paired Pt and Cu atoms modifies the electronic structure of the Pt site through d-orbital interactions,resulting in an optimal moderate interaction of the metal atom with the different sulfide species.This optimal interaction enhanced charge transfer kinetics and promoted sulfur redox reactions.Our work thus provides important insights on the atomic scale into the synergistic effects operative in dual-atom catalysts and will thus pave the way to electrocatalysts with enhanced efficiency for high-performance Li–S batteries.展开更多
基金funding support from the National Natural Science Foundation of China(Nos.U2032202,22125902 and 21975243)DNL cooperation Fund,CAS(No.DNL202020)+1 种基金Fundamental Research Funds for the Central Universities(Nos.WK2060000013 and YD3430002001)Users with Excellence Program of Hefei Science Center CAS(No.2021HSC-UE002)。
文摘Single atom catalysts(SACs)with atomically dispersed transition metals on nitrogen-doped carbon supports have recently emerged as highly active non-noble metal electrocatalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),showing great application potential in Zn-air batteries.However,because of the complex structure-performance relationships of carbon-based SACs in the oxygen electrocatalytic reactions,the contribution of different metal atoms to the catalytic activity of SACs in Zn-air batteries still remains ambiguous.In this study,SACs with atomically dispersed transition metals on nitrogen-doped graphene sheets(M-N@Gs,M=Co,Fe and Ni),featured with similar physicochemical properties and M-N@C configurations,are obtained.By comparing the on-set potentials and the maximum current,we observed that the ORR activity is in the order of Co-N@G>Fe-N@G>Ni-N@G,while the OER activity is in the order of Co-N@G>Ni-N@G>Fe-N@G.The Zn-air batteries with Co-N@G as the air cathode catalysts outperform those with the Fe-N@G and Ni-N@G.This is due to the accelerated charge transfer between Co-N@C active sites and the oxygen-containing reactants.This study could improve our understanding of the design of more efficient bifunctional electrocatalysts for Zn-air batteries at the atomic level.
基金This work was supported by the Natural Science Foundation of China(22125902,21975243,U2032202,and U1932201)the National Program for Support of Topnotch Young Professionals,the DNL Cooperation Fund,CAS(DNL202020)+2 种基金the Anhui Science Fund for Distinguished Young Scholars(2208085J15)the National Key R&D Program of China(2022YFA1504101)Users with Excellence Program of Hefei Science Center CAS(2021HSC-UE002).
文摘Sulfur redox reactions render lithium–sulfur(Li–S)batteries with an energy density of>500Whkg−1 but suffer a low practical capacity and fast capacity fade due to sluggish sulfur redox reaction(SRR)kinetics,which lies in the complex reaction process that involves a series of reaction intermediates and proceeds via a cascade reaction.Here,we present a Pt–Cu dual-atom catalyst(Pt/Cu-NG)as an electrocatalyst for sulfur redox reactions.Pt/Cu-NG enabled the rapid conversion of soluble polysulfide intermediates into insoluble Li2S2/Li2S,and consequently,it prevented the accumulation and shuttling of lithium polysulfides,thus outperforming the corresponding single-atom catalysts(SACs)with individual Pt or Cu sites.Operando X-ray absorption spectroscopy and density functional theory calculations revealed that a synergistic effect between the paired Pt and Cu atoms modifies the electronic structure of the Pt site through d-orbital interactions,resulting in an optimal moderate interaction of the metal atom with the different sulfide species.This optimal interaction enhanced charge transfer kinetics and promoted sulfur redox reactions.Our work thus provides important insights on the atomic scale into the synergistic effects operative in dual-atom catalysts and will thus pave the way to electrocatalysts with enhanced efficiency for high-performance Li–S batteries.
