Engineering of cation and anion vacancies in Co₃O₄ thin nanosheets by laser irradiation for more advancement of oxygen evolution reaction

Atomic vacancy has been demonstrated to generate new energy states in the bandgap whereby providing more active sites in many electrocatalytic processes. In this work, a novel process is developed to yield both Co and O vacancies in the synthetical Co₃O₄ nanosheets when subjected to a laser beam. The method, capable of creating both Co and O vacancies and embarking upon the prediction of the number of vacancies generated, is more reliable/controllable over other methods. The coupling of two types of vacancies eases the occurrence of Co₃O₄ oxidation reaction at a very low overpotential, which then facilities the OER at an overpotential of 290 mV with a small Tafel slope of 76 mV dec⁻¹, much better than the pristine Co₃O₄ and the benchmark RuO₂. DFT calculations suggest that the induced multi- vacancies create trap state in the bandgap of Co₃O₄ promoting the adsorption capability and advancing the water splitting.