Inherent Oxygen Vacancies Boost Surface Reconstruction of Ultrathin Ni-Fe Layered-Double-Hydroxides toward Efficient Electrocatalytic Oxygen Evolution

Unraveling structure-related reconstruction during oxygen evolution reaction (OER) and its correlation with intrinsic electrocatalytic activity is of great significance for designing better catalysts but unfortunately remains elusive. Herein, ultrathin Ni-Fe layered-double-hydroxides (LDH) with inherent oxygen vacancies ( V O ) are successfully fabricated via coprecipitation under a controlled manner, which accomplish a quite low overpotential of 230 mV at 10 mA cm –2 in 1.0 M KOH and perform among the best of recently reported nonprecious electrocatalysts. During the OER, inherent V O is experimentally and theoretically evidenced to boost surface reconstruction and the operando formation of p–n interfaces (i.e., γ-Ni-Fe LDH/α-Ni-Fe LDH) via deprotonation. On such reconstructed interfaces, the V O in both surface γ-Ni-Fe LDH and bulk α-Ni-Fe LDH can alter the electron densities of metal sites and subsequently optimize the free energies of a multistep OER pathway, which accounts for the boosted OER activity and, more importantly, identifies the correlation of electrocatalysis with both the catalyst surface and bulk.