Metal-free mesoporous carbon with higher contents of active N and S codoping by template method for superior ORR efficiency to Pt/C

Carbon materials with more exposed N or S atoms result in higher activity for oxygen reduction reaction. In this paper, mesoporous carbon based materials with 5.3 at% of N and 7.1 at% of S are synthesized (defined as porous-S-N-C). The solid core mesoporous shell silica as template results in mesoporous structure of the porous-S-N-C which favors mass transfer and higher doping (both increase by ∼20%) and exposing of active N and S atoms. The electrochemical characterization results show that the mesoporous structure and the S modification favor much to the N-C based catalysts in catalyzing ORR. Typically, the porous-S-N-C has a 3.99 electron transfer number at 0.4 V, and higher ORR efficiency, much better CO tolerance, much better methanol tolerance and much higher electrochemical stability than commercial Pt/C. This novel method of improving the contents of doped and exposed N and S atoms is imagined to be applied to preparation of other high-content-heteroatom doped materials.