Transforming Co3O4 nanosheets into porous N-doped Co O nanosheets with oxygen vacancies for the oxygen evolution reaction

Cobalt oxides have been widely investigated as promising replacements for noble metal-based catalysts for oxygen evolution reaction (OER). Herein, we, for the first time, have obtained porous CoxOy nanosheets with N-doping and oxygen vacancies by etching Co3O4 nanosheets with NH3 plasma. Comparing with the pristine Co3O4 nanosheets (1.79 V), the porous CoxOy nanosheets with N-doping and oxygen vacancies have a much lower potential of 1.51 V versus RHE to reach the current density of 10 mA cm−2. The obtained sample has a lower Tafel slope of 68 mV dec−1 than the pristine Co3O4 nanosheets (234 mV dec−1). The disclosed Co2+, which is responsible for the formation of active sites (CoOOH), N-doping and oxygen vacancies, gives rise to better performance of OER.