In situ fabrication of cobalt sulfide-decorated N,S co-doped mesoporous carbon and its application as an electrocatalyst for efficient oxygen reduction reaction

Abstract

Designing an efficient electrocatalyst for facile oxygen reduction reaction (ORR) is essential to achieve higher fuel cell performance. Herein, we demonstrate a simple in situ process to synthesize cobalt sulfide-decorated N and S co-doped mesoporous carbon (Co₉S₈/N,S-MC) and evaluated its electrocatalytic activity for ORR in alkaline media. Porous carbon has great potential as a support material due to its well-defined porous architecture, which facilitates the mass transport. Here, the Co₉S₈/N,S-MC electrocatalyst was designed through a soft template route using pluoronic-F127 as a structure-directing agent, phloroglucinol-formaldehyde resin as a carbon source, and thiourea and cobalt acetate as N, S and Co sources, respectively. The combined effects of cobalt sulfide, heteroatoms and the well-defined porous architecture of mesoporous carbon resulted in the excellent ORR performance of the Co₉S₈/N,S-MC catalyst. Consequently, the optimized Co₉S₈/N,S-MC catalyst exhibited an onset potential and limiting current density of 0.87 V vs. RHE, and 3.40 mA cm⁻², respectively. These values were very close to those of the commercial Pt–C catalyst with only a difference of 50 mV and 80 mA cm⁻², but the Co₉S₈/N,S-MC catalyst also showed a 30 mV higher half-wave potential and excellent long-term stability compared to those of the commercial Pt/C catalyst. These interesting results suggested the good potential application of Co₉S₈/N,S-MC as ORR electrocatalysts with longer stability in fuel cells.