Efficient oxygen electroreduction over ordered mesoporous Co–N-doped carbon derived from cobalt porphyrin

Abstract

The demand for directly converting chemical energy generated by exothermal redox reactions into electrical energy has increased markedly in recent years and motivates the development of novel electrochemical power sources. The use of fuel cell technology may be the most promising solution for electrochemical propulsion in electric vehicles. However, at present, the design and synthesis of high-performance and low-cost catalysts for the oxygen reduction reaction (ORR) still remains a significant challenge. Here, a high-performance Co-based carbon electrocatalyst (Co–N–GC) for the ORR is prepared by a simple wet-impregnation nanocasting method using SBA-15 as a hard template and water-soluble cobalt porphyrin as a precursor. The prepared catalysts with Co–N_x moieties have ordered mesoporous channels, and high specific surface area and degree of graphitization. In 0.1 M HClO₄ medium, the ORR over Co–N–GC prepared at the optimized heat-treatment temperature (800 °C) exhibits a positive half-wave potential (0.79 V) and higher ORR current density (5.6 mA cm⁻² at 0.2 V) compared to commercial Pt/C (20 wt%) catalysts. Moreover, the prepared Co–N–GC materials possess intrinsic long-time stability and the excellent methanol resistance toward the ORR in both acidic and alkaline media, and may serve as a promising alternative to Pt/C materials for the ORR in the widespread implementation of fuel cells.