Defect structure regulation and mass transfer improvement of cobalt-based oxides for enhanced oxygen evolution reaction

Abstract

Cobalt-based oxides have been widely studied as electrocatalysts for the oxygen evolution reaction (OER). Improving the intrinsic activity of the OER and increasing the number of active sites are two strategies used to enhance the OER performance. However, combining these two strategies to improve the catalytic activity of the OER for CoO catalysts has rarely been reported. Herein, we introduce a simple strategy to prepare CoO for the OER by fine tuning the calcination temperature of the Co(OH)2 precursor. The physical and chemical characterizations of these materials confirm the formation of oxygen vacancies and porous structures. Among the Co-based oxides prepared at different temperatures (300–600 °C), CoO prepared at 500 °C shows the best OER performance. The intrinsic catalytic activity and number of active sites of the CoO nanoflowers are also improved, which is attributed to the formation of oxygen vacancies and porous structures. This work introduces a simple strategy to improve the catalytic activity of the OER for transition metal-based oxides by improving their intrinsic catalytic activity and simultaneously increasing the number of active sites.