Unveiling Oxygen Vacancy Engineering in CoMo‐Based Catalysts for Enhanced Oxygen Evolution Reaction Activity

Abstract Oxygen vacancy (V _O ) engineering is widely regarded as a key strategy for enhancing CoMo‐based catalysts for oxygen evolution reaction (OER) while understanding their formation mechanisms and role in boosting OER activity remains a significant challenge. Herein, a CoMoO _x system doped is developed with different 3 d ‐orbital atoms M (V, Ni, Zn, and Mn) to investigate the construction and stabilization of V _O and its crucial role in OER performance. In situ and ex situ measurements along with theoretical calculations demonstrate that V doping adjusts the bandgap between the CoMo‐ d and O ‐p orbitals, leading to the transfer of electrons from the O‐ p orbitals to the M‐ d orbitals, thereby promoting the formation of V _O . The formation of V _O leads to an upshifted d ‐band center, optimizing the desorption of oxygen intermediates on V _O ‐CoMoVO _x and lowering the energy barrier of the rate‐determining step (RDS), thereby enhancing the catalyst's activity. Additionally, V doping promotes electron transfer from Co to V atoms, stabilizing the V _O and ultimately improving the catalyst's stability. The resulting V _O ‐CoMoVO _x catalyst delivered attractive activity (overpotential of 248 mV at 10 mA cm ⁻² ) and durability over 600 h. This study offers a rational method for designing efficient OER electrocatalysts.