Fe/N/S Co-doped Porous Carbon from the Co-processing Residue of Coal and Heavy Oil for an Efficient Oxygen Reduction Reaction

The development of novel non-noble electrocatalysts to replace Pt-based materials has always been the focus of electrocatalysis research. The co-processing residue of coal and heavy oil (CR) is a carbonaceous waste with high quantities of heteroatomic compounds from coal liquefaction industries. With the aid of alkali activation and melamine doping operations at a high temperature, the CR was transformed into a material with a large specific surface area, rich hierarchical pores, and Fe, N, and S doping for application in the oxygen reduction reaction (ORR) as an electrocatalyst. The structural features and reaction performances of synthesized electrocatalysts with different components in the CR as precursors were compared. The ORR half-wave potential of the electrocatalyst with the direct utilization of the CR (0.82 V) was close to the commercial 20% Pt/C (0.85 V) under alkaline conditions, which surpassed that of the electrocatalysts derived from the toluene-soluble (0.78 V) or toluene-insoluble (0.79 V) components in the CR. The asphaltenes in the toluene-soluble component of CR and the mineral templates and the Fe-containing active species in the toluene-insoluble component of CR showed a synergistic effect on the improvement of ORR performances, which may shed light on the high-valued utilization of CR materials.