Hollow Co₃O₄ nanocapsules/N-doped carbon with oxygen vacancies as efficient electrocatalysts towards oxygen evolution reaction

To enhance the catalytic activity of oxygen evolution reaction (OER), tremendous efforts have been contributed to tune the morphology, structure and component of the commonly used transition metal oxides electrocatalysts. Herein, hollow Co3O4 nanocapsules/N-doped carbon (Co3O4/NC) composite was synthesized via combining a carbonization process and an oxidation route by employing biomass as carbon source. The obtained composite presents a porous hierarchical construction, in which hollow Co3O4 nanocapsules with an average diameter of 60 nm are uniformly dispersed and anchored on the carbon carrier. Electrochemical measurements reveal that the resulted Co3O4/NC presents outstanding catalytic performance towards OER with only 328 mV to obtain the current density of 10 mA cm(-2) along with a Tafel slope of 84 mV dec(-1), which are superior than those of benchmark catalyst RuO2. Besides, the influences of the loading amount of Co3O4 and sintering temperature on OER performance are studied in detail. The outstanding catalytic activity can be ascribed to the typical hollow nanocapsules structure and abundant oxygen deficiency, which can afford a mass of catalytic active sites. Therefore, this work puts forward valuable reference for the design of high-efficiency biomass derived catalysts in the field of OER.