Disordering the Atomic Structure of Co(II) Oxide via B-Doping: An Efficient Oxygen Vacancy Introduction Approach for High Oxygen Evolution Reaction Electrocatalysts.

The introduction of oxygen (O) vacancies has been considered to be an important but challenging way to enhance the activity of electrocatalysts for the oxygen evolution reaction (OER). Substitution by heteroatoms with high electron-donating ability may be a feasible strategy for triggering O-vacancies to maintain thermodynamic stability. Herein, density functional theory (DFT) calculations predict that the incorporation of boron (B) is favorable to the generation of O-vacancies in transition metal oxides. Then, CoO nanowires with O-vacancies are prepared via incorporation of B using a facile pyrolysis strategy. As evidenced by the combined results of electron paramagnetic resonance spectroscopy and X-ray absorption near edge structure, O-vacancies in CoO are mainly derived from the disordering of the local structure caused by B doping. DFT calculation results further reveal that the oxidation of *OOH is the rate-limiting step for O-vacancies enriched CoO in the OER and that the presence of O-vacancies can efficiently lower the reaction barrier for breaking CoO bond, contributing to the improvement of OER kinetics. As expected, the O-vacancies enriched CoO exhibits a low overpotential of 280 mV to reach the current density of 10 mA cm-2 under basic conditions.