Preparation of S self-doped porous carbon nanospheres as ORR catalysts derived from block copolymer grafted S group

Abstract

In order to increase the activity and decrease the cost of oxygen reduction reaction (ORR) catalyst, S self-doped porous carbon nanospheres ORR catalyst was prepared by pyrolyzing the block copolymer F127 grafted with 3-mercapto-propanoicaci. The composition and microstructure were characterized and its electrochemical performance was also investigated in O2-saturated 0.1 M KOH solutions. The results showed that, among all the obtained samples, C-S-750 had a porous carbon nanosphere structure with the doped sulfur of 7.08 at % and a maximum specific surface area of 776.3 m2/g. The onset potential, half-wave potential and limiting current density of C-S-750 were 0.92 V (versus RHE) and 0.80 V (versus RHE) and 5.77 mA/cm2@0.45 V in O2-saturated 0.1 M KOH solution, respectively, which were close to that of commercial 20% Pt/C catalysts. This provides a new way to introduce and increase the doped heteroatom in metal-free ORR catalysts.