Defects have been found to enhance the electrocatalytic performance of NiFe-LDH for oxygen evolution reaction (OER). Nevertheless,their specific configuration and the role played in regulating the surface reconstruction of electrocatalysts remain ambiguous.H erein, cationic vacancy defects are generated via aprotic-solvent-solvation-induced leaking of metal cations from NiFe-LDH nanosheets.D FT calculation and in situ Raman spectroscopic observation both reveal that the as-generated cationic vacancy defects tend to exist as V M (M = Ni/Fe);under increasing applied voltage,they tend to assume the configuration V MOH ,a nd eventually transform into V MOH-H whichisthe most active yet most difficult to form thermodynamically.M eanwhile,w ith increasing voltage the surface crystalline Ni(OH) x in the NiFe-LDH is gradually converted into disordered status;u nder sufficiently high voltage when oxygen bubbles start to evolve,l ocal NiOOH species become appearing,w hich is the residual product from the formation of vacancy V MOH-H .T hus,w ed emonstrate that the cationic defects evolve along with increasing applied voltage (V M ! V MOH ! V MOH-H ), and reveal the essential motif for the surface restructuration process of NiFe-LDH (crystalline Ni(OH) x ! disordered Ni(OH) x ! NiOOH). Our work provides insight into defect-induced surface restructuration behaviors of NiFe-LDH as at ypical precatalyst for efficient OER electrocatalysis.

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Active component management and microengineering of metal nanoparticles are significant challenges for efficient M/N/C electrocatalysts, as a crucial electrode material for reversible zinc–air batteries, because of the lack of a multifunctional structural strategy in the electrocatalytic preparation process. Here, a convenient, one-step pyrolysis method was introduced into the preparation process of a difunctional electrocatalyst, an Fe-, Co-, and N-codoped carbon-based cube hybrid (Co7Fe3/CFNC) with abundant active components, including metallic Co7Fe3 nanoparticles and Fe/Co–N x species. The as-constructed Co7Fe3/CFNC demonstrates impressive activity/stability for ORR/OER. Moreover, practical zinc–air battery building with Co7Fe3/CFNC electrocatalysts reveals a superior cycling stability for 224 h. Our work could educate a new applicable branch for designing multifunctional catalysts and regulating their active sites to apply the energy and environment.

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