N/S-Me (Fe, Co, Ni) doped hierarchical porous carbons for fuel cell oxygen reduction reaction with high catalytic activity and long-term stability

A series of novel and high-performing oxygen reduction reaction (ORR) catalysts based on N/S-Me-doped (Me = Fe, Co, Ni) hierarchical porous carbons (N/S-Fe-HPC, N/S-Co-HPC and N/S-Ni-HPC) have been synthesized by a green and cost-effective method combining a simple silicate templated two-step graphitization of the impregnated carbon. After optimization of the porous structures and enlargement of the BET specific surface area by combining the silicate template and the Fe-, Co- and Ni-metal sulfates, the obtained N/S-Me-HPC catalysts exhibit excellent ORR performance in both alkaline and acidic media. In particular, N/S-Fe-HPC shows superior catalytic ORR performance compared to commercially available 20% Pt/C in alkaline medium reflected by the onset potential of 0.98 V and half-wave potential of 0.86 V, and comparable ORR activity in acidic media with the onset potential of 0.84 V and half-wave potential of 0.73 V. In addition, the N/S-Fe-HPC catalyst exhibits excellent long-term stability and a high methanol tolerance. The outstanding electrochemical performance of such catalysts thereby makes it possible for these non-noble catalysts to replace the commercial Pt/C in both fuel cell and metal-air battery applications. (C) 2016 Elsevier Ltd. All rights reserved.