The breaking of nonpolar N≡N bond of dinitrogen is the biggest dilemma for electrocatalytic nitrogen reduction reaction(NRR)application,driving electron migration between catalysts and N≡N bond(termed“πback-donat...The breaking of nonpolar N≡N bond of dinitrogen is the biggest dilemma for electrocatalytic nitrogen reduction reaction(NRR)application,driving electron migration between catalysts and N≡N bond(termed“πback-donation”process)is crucial for attenuating interfacial energy barrier but still remains challenging.Herein,using density functional theory calculations,we revealed that constructing a unique hetero-dicationic Mo^(4+)-Mo^(6+)pair could effectively activate N≡N bond with a lying-down chemisorption configuration by an asymmetrical“πback-donation”process.As a proof-of-concept demonstration,we synthesized MoO_(2)@MoO_(3)heterostructure with double Mo sites(Mo^(4+)-Mo^(6+)),which are embedded in graphite,for electrochemical nitrogen reduction.Impressively,this hetero-dicationic Mo^(4+)-Mo^(6+)pair catalysts display more excellent catalytic performance with a high NH_(3)yield(60.9μg·h^(-1)·mg^(-1))and Faradic efficiency(23.8%)as NRR catalysts under ambient conditions than pristine MoO_(2)and MoO_(3).Operando characterizations using synchrotron-based spectroscopic techniques identified the emergence of a key^(*)N_(2)Hy intermediate on Mo sites during NRR,which indicates that the Mo sites are active sites and the NRR process tends to follow an associative mechanism.This novel type of hetero-dicationic catalyst has tremendous potential as a new class of transition metal-based catalysts with promising applications in electrocatalysis and catalysts for energy conversion and storage.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(Nos.11975234,11775225,12075243,and 12005227)the Users with Excellence Program of Hefei Science Center CAS(Nos.2021HSC-UE002,2020HSCUE002,and 2019HSC-UE002)+5 种基金the Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology(No.2020HSC-CIP013)the Postdoctoral Science Foundation of China(Nos.2019M662202,2020M682041,and 2020TQ0316)the Fundamental Research Funds for the Central Universities(No.WK2310000103)The support from the Ministry of Science and Technology of China(No.2017YFA0204904)is gratefully acknowledgedThe numerical calculations in this paper have been done on the supercomputing system in the Supercomputing Center of University of Science and Technology of ChinaThis work was partially carried out at the USTC Center for Micro and Nanoscale Research and Fabrication.
文摘The breaking of nonpolar N≡N bond of dinitrogen is the biggest dilemma for electrocatalytic nitrogen reduction reaction(NRR)application,driving electron migration between catalysts and N≡N bond(termed“πback-donation”process)is crucial for attenuating interfacial energy barrier but still remains challenging.Herein,using density functional theory calculations,we revealed that constructing a unique hetero-dicationic Mo^(4+)-Mo^(6+)pair could effectively activate N≡N bond with a lying-down chemisorption configuration by an asymmetrical“πback-donation”process.As a proof-of-concept demonstration,we synthesized MoO_(2)@MoO_(3)heterostructure with double Mo sites(Mo^(4+)-Mo^(6+)),which are embedded in graphite,for electrochemical nitrogen reduction.Impressively,this hetero-dicationic Mo^(4+)-Mo^(6+)pair catalysts display more excellent catalytic performance with a high NH_(3)yield(60.9μg·h^(-1)·mg^(-1))and Faradic efficiency(23.8%)as NRR catalysts under ambient conditions than pristine MoO_(2)and MoO_(3).Operando characterizations using synchrotron-based spectroscopic techniques identified the emergence of a key^(*)N_(2)Hy intermediate on Mo sites during NRR,which indicates that the Mo sites are active sites and the NRR process tends to follow an associative mechanism.This novel type of hetero-dicationic catalyst has tremendous potential as a new class of transition metal-based catalysts with promising applications in electrocatalysis and catalysts for energy conversion and storage.
