Rational design and synthesis of sandwich-like iron nitride-graphene composites as efficient catalysts for oxygen reduction reaction

Abstract

Iron-based catalysts for oxygen reduction reaction (ORR) have attracted considerable attention as one of the most promising candidates owing to their low cost and high catalytic activity. Herein, sandwich-like Fe, N-graphene composites catalysts were rationally designed and synthesized by a two-step procedure using graphene oxide and pyrrole as chemicals. The layered graphene oxide @ polypyrrole precursor was synthesized by in-situ polymerization of pyrrole with GO/FeCl3 complexes served as both template and oxidant. The resulted FeNC catalysts obtained from above precursors annealed at 825 °C with sandwich-like structure of Fe species between graphene and carbon coating as the electrocatalysts for ORR showed that, comparable to the commercial Pt/C catalyst, positive onset potential (−0.08 V vs Ag/AgCl), high ORR limiting current density (5.87 mA cm−2 at −0.6 V), favoured an apparent 4-electron transfer pathway, outstanding stability, excellent methanol tolerance. Those excellent properties of rational designed FeNC catalysts can be attributed to the suitable feeding order of chemicals to keep the advantages of graphene with high specific surface area and provide more effective surface active sites, and protection for active sites by carbon layers from polypyrrole.