Highly Mesoporous Graphitic Catalysts with Ternary Doping Structure towards Highly Efficient Oxygen Reduction

Abstract

A new template-approach was demonstrated to fabricate Co, N and S co-doped nanoporous graphitic structure for efficiently catalyzing ORR. For preparing such catalyst, a core-shell precursor (FeX@SNDG) was prepared with S and N co-doped graphitic shells by catalytic pyrolysis, and then S and N co-doped nanoporous graphitic structure was purified by removing ferrous cores with mixed acids. The existence of S-doping could modify the active sites to enhance the catalysis of ORR, compared with only Co and N co-doped carbonous catalysts. Co-SN-GCs have more positive onset potential (0.97 vs. 0.93 V) and higher kinetic current density (6.2 vs. 5.5 mA cm-2 at 0.6 V) than Fe-SN-GCs; density-functional theory calculations indicated formation barrier is much lower at Co-SN sites than at Fe-SN sites (0.573 vs. 0.729 eV) in the rate-determining step of oxygen reduction reaction.