Nitrogen-Doped Ordered Mesoporous Carbon/Graphene Framework As Dual Electrocatalyst for Oxygen Reduction and Evolution Reactions

Abstract

One important research topic in electrocatalysis is electrochemical redox between H2O and O2 for the design of regenerative electrochemical energy storage and conversion system, which involves oxygen reduction reaction (ORR) during discharging process and oxygen evolution reaction (OER) upon charging process. Thus, it is of great importance to develop a dual functional electrocatalyst which is active in both ORR and OER and can reduce the usage of noble metals.We report the synthesis of highly ordered N-doped mesoporous carbon/graphene frameworks (N-MCF/N-MGF), which possessed large surface area, high porosity, excellent internal diffusion property, and superior intrinsic conductivity and exhibited promising catalytic properties in both ORR and OER. As a dual catalyst, the N-MGF exhibited overpotential as low as 324 mV for harvesting 10 mA cm-2 OER current density, which was lower than most of previously reported carbon-based materials and were comparable with the benchmarking noble metal oxide catalysts. The catalyst was also durable under both OER and ORR conditions. These results presented a low-cost dual ORR/OER electrocatalyst with high activity and good durability as well as their negligible internal diffusion resistance, which could be potentially utilized and implemented in renewable energy techniques such as metal-air batteries, fuel cells, and water splitting devices.