Achievement of a novel porous non-noble-metal catalyst with excellent oxygen reduction reaction activity: Promoting the commercialization of alkaline fuel cells

One of the urgent problems in the commercialization of fuel cells is the high cost of electrode materials due to the use of Pt/C as the catalyst for oxygen reduction reaction (ORR). Herein, by taking advantages of the metal-organic frameworks, a novel ORR catalyst of Co@Co₉S₈–N/C with composite porous structure is synthesized with a facile coprecipitation-pyrolysis method. Co@Co₉S₈–N/C is composed of graphitic carbon skeleton with Co₉S₈ covered Co nanoparticles (Co@Co₉S₈) and nitrogen atoms doping on, on which Co@Co₉S₈ and pyridinic N provide catalytic sites for ORR. The N, S doped surrounding graphitic carbon skeleton after pyrolysis and vulcanization processes can protect the electrochemical active sites from deactivation. The fabricated Co@Co₉S₈–N/C with abundant catalytic active sites performs excellent ORR activity and stability. Thereafter, the structure of the Co@Co₉S₈–N/C is optimized by changing the Zn/Co ratio in the precursor to improve its ORR performance. The results show that with the Zn/Co ratio of 3:2, Co@Co₉S₈–N/C gives the best ORR activity relying on its well specific surface area, sufficient and uniform-dispersed catalytic sites. Based on this, the Co@Co₉S₈–N/C catalytic alkaline direct glucose fuel cells perform better than the Pt/C catalytic one.