Tailored synthesis of hybrid iron-nitrogen-graphene with reduced carbon xerogel as an efficient electrocatalyst towards oxygen reduction

In this study, a non-precious metal-based electrocatalyst consisting of nitrogen-doped iron-coated reduced graphene oxide (FeNG) on carbon xerogel towards oxygen reduction reaction (ORR) in alkaline media is reported. Herein, we describe a facile three-step synthesis route towards enhanced ORR activity. The effect of pyrolysis temperature and the resulting structural variations of the designated catalyst towards ORR were investigated. The as-synthesized carbon xerogel samples were reduced (rCX) and then pyrolyzed at different temperatures, viz., 700, 900, and 1100 °C, followed by the incorporation of FeNG, and their performance towards ORR was studied. The resultant rCXFeNG (reduced carbon xerogel-iron-nitrogen-doped graphene) catalyst pyrolyzed at an optimum temperature of 1100 °C (rCXFeNG-1100) showed enhanced electrocatalytic performance towards ORR and exhibited an onset potential of 0.84 V vs. RHE (reversible hydrogen electrode). Besides, it is remarkable that rCXFeNG-1100 delivers a limiting current density of 5.55 mA cm−2, which is fairly equivalent to that of the commercial Pt/C electrocatalyst. It is noteworthy that the rCXFeNG-1100 electrocatalyst showed a four-electron transfer pathway for ORR and showed better stability and improved durability outperforming the commercial Pt/C electrocatalyst. The present study opens up a promising approach for the design and fabrication of cost-effective non-precious ORR electrocatalysts for alkaline polymer electrolyte fuel cells.