Synergistic Enhancement of Electrocatalytic Activity toward Oxygen Reduction Reaction in Alkaline Electrolytes with Pentabasic (Fe, B, N, S, P)-Doped Reduced Graphene Oxide

As alternatives to Pt-based electrocatalysts, the development of nonprecious metal catalysts with high performance in the cathodic oxygen reduction reaction (ORR) is highly desirable for widespread use in fuel cells. Here we report a simple approach for preparing pentabasic (Fe, B, N, S, P)-doped reduced graphene oxide (rGO) via a two-step doping method of adding boric acid and ferric chloride to ternary (N, S, P)-doped rGO (NSPG). Electrochemical investigation of the composites for the ORR revealed that simultaneously doping appropriate amounts of Fe and B into the NSPG produced a synergistic effect that endowed the prepared catalyst with both a positively shifted ORR half-wave potential and high selectivity for the 4e(-) reduction of O-2. The optimized Fe2B-NSPG catalyst approached a 4e(-) process for the ORR with a half-wave potential (E-1/2=0.90 V vs. RHE) even 30 mV higher than that of the commercial Pt/C catalyst in alkaline solution. Furthermore, relative to the Pt/C catalyst, the Fe2B-NSPG demonstrated superior stability and excellent tolerance of the methanol cross-over effect. This simple method afforded pentabasic (Fe, B, N, S, P)-doped rGO as a promising nonprecious metal catalyst used for alkaline fuel cells.