Facile synthesis of nitrogen, sulfur dual-doped porous carbon via carbonization of coal tar pitch and MgCl2·6H2O for oxygen reduction reaction

Abstract

Developing heteroatom-doped carbon catalysts toward oxygen reduction reaction (ORR) to replace platinum (Pt)-based catalysts is a promising strategy. Herein, nitrogen (N), sulfur (S) dual-doped porous carbons (NS@C-x-y) were prepared via a one-step carbonization of the mixture of acid treatment coal tar pitch (CTP) and MgCl2·6H2O, through in situ self-generating MgO template route. N and S were successfully introduced into the carbon framework of CTP by mixed acid treatment, leading to N, S co-doping especially pyridinic-N, graphitic-N, and C-S-C as ORR active sites. Benefiting from the fluffy lump graphitic structure, large surface areas, and synergistic effect between N and S electrocatalytic sites, the resulting samples demonstrate superior ORR performances with the highest diffusion-limited current density of 5.97 mA cm−2 and half-wave potential of 0.82 V (vs. RHE), long-term stability, and excellent methanol tolerance in alkaline medium, which are competitive with Pt/C catalyst.