Engineering Cationic Vacancies in Octahedral Sites of Co3O4 for High-Efficiency Oxygen Evolution

Co3O4 has been regarded as the promising oxygen evolution reaction (OER) catalyst to replace the noble-metal catalyst. The atomic cationic vacancy defects can elicit the localized electron redistribution to regulate the electronic structure of the host materials. Hence, the Co3O4 nanosheet arrays with different amount of cationic vacancies have been synthesized by a facile three-step reaction process in this paper. With the increasing number of cationic vacancies, the amount of Co3+ which possesses the better OER activity is increased gradually. DFT computational results further indicate that the cationic vacancies can increase the number of electrons of per Co atom and optimize the adsorption energy of the intermediate product. As a result, the optimized V0.3-Co3O4/CC electrode displays excellent OER performance in alkaline electrolyte with the overpotential of 240 mV at 10 mA cm-2, tafel slope of 72.2 mV dec-1 and superior stability, which is much better than the pure Co3O4 and commercial IrO2.