Cobalt-stabilized oxygen vacancy of V2O5 nanosheet arrays with delocalized valence electron for alkaline water splitting

Stabilizing oxygen vacancy for oxides-based electrocatalysts is the most challenging to achieve high-efficient overall water splitting in alkaline media. Herein, the oxygen vacancy (OV) engineered V2O5 nanosheet arrays have been demonstrated as bifunctional electrocatalysts, in which cobalt ions are utilized to tailor OV content and keep steady. The maxmized OV engineering can render the valance electrons shift to higher binding energy with moderate surface chemical states, optimizing H* adsorption on vanadium center at the electrochemical interface. Consequently, a superlow overpotential of 51 mV is required to attain a current density of 10 mA cm−2 for hydrogen evolution with 24 h durable stability. The corresponding overpotential is about 277 mV for oxygen evolution. After assembling a two-electrode electrolyzer, it shows a very low voltage of 1.55 V at 10 mA cm−2. This work provides a viable cationic induced OV formation strategy for oxides-based electrocatalysts to obtain satisfied catalytic activity and stability.