Investigation on the Catalytic Performance of Reduced-Graphene-Oxide-Interpolated FeS₂ and FeS for Oxygen Reduction Reaction

The oxygen reduction reaction (ORR) plays a key role in many kinds of energy conversion and energy storage devices, especially in fuel cells. Developing low-cost, easily prepared, and high-efficiency catalysts is a crucial factor for the large-scale applications of fuel cells. Herein, we report the reduced graphene oxide (rGO) interpolated FeS₂ and FeS as low cost and high performance electrocatalyst for ORR in the alkaline electrolyte. Cyclic voltammetry tests indicate that the onset potential of the ORR for FeS₂@rGO is −0.142 V, which is close to the state-of-the-art commercial Pt/C (-0.114 V) catalyst. A low Tafel slope of ∼ 98 mV/decade and high durability are also observed for the FeS₂@rGO composite for ORR. The reaction kinetics study shows that the rGO-interpolated FeS₂ catalyzed ORR major happen through 4-electron pathway, but the rGO-interpolated FeS catalyzed ORR major happen through mixed 2-electron and 4-electron pathway. The S−S bond of FeS₂ play the major role for the happening of ORR through 4-electron pathway.