Facile synthesis of nitrogen and sulfur dual-doped graphitized carbon microspheres and their high performance in the oxygen reduction reaction

A facile protocol for producing porous carbon spheres co-doped with nitrogen and sulfur is presented. Thiourea resorcinol-formaldehyde (RF) copolymerized resin microspheres were used as precursors. After only a simple calcination, the uniformly N, S co-doped graphitized carbon spheres could be obtained. Synergistic effects produced by the tunable content of N, S heteroatoms combined with the porous graphitized structures makes this one of the excellent non-platinum-based catalysts for the oxygen reduction reaction. When used in alkaline media, the materials exhibit high onset and half-wave potentials, high kinetic current density and a four-electron transfer pathway with low hydrogen peroxide yield, which is comparable to the commercial Pt/C catalyst. More importantly, the long-term durability test confirms its excellent stability for practical applications.