Nitrogen and sulfur dual-doped hollow mesoporous carbon spheres as efficient metal-free catalyst for oxygen reduction reaction

Abstract

Developing a cheap and efficient oxygen reduction reaction (ORR) catalyst is one of the emerging issues. The doped carbon materials have attracted much attention due to the controllable and cheap synthesis methods. In this work, the nitrogen and sulfur dual-doped hollow mesoporous carbon sphere (NS-HMCS) has been synthesized through a hard-template method. During the co-polymerization process of dopamine (DA) and cysteamine (CA), the nitrogen (N) and sulfur (S) sites are introduced into the carbon skeleton at the same time, which simplifies the tedious steps in the post-modification of carbon materials. The obtained NS-HMCS-32 exhibits high content of nitrogen about 4.8% and sulfur about 1.4%. NS-HMCS-32 has a high specific surface areas (898 m2 g−1) and a large pore volume (2.99 cm3 g−1). During the ORR measurement, the half-wave potential of NS-HMCS-32 reaches up to 0.77 V vs. RHE. Moreover, NS-HMCS-32 reveals a better durability than commercial Pt/C and 79.2% of current density remains after 9 h chronoamperometry test. This work provides a design idea for dual-doped carbon materials and the obtained NS-HMCS is a potential candidate for metal-free catalyst in fuel cells.