Enhancing Oxygen Electroreduction Activity of Single-Site Fe–N–C Catalysts by a Metal Support

Development of cost-effective and highly-active platinum group metal-free (PGM-free) electrocatalysts for the oxygen reduction reaction (ORR) has recently attracted a great deal of attention. Among various PGM-free chemistries, FeNx moieties atomically dispersed into the host carbon have emerged as promising candidates. In this work, we employ density functional theory calculations to explore the idea of ORR activity enhancement of the FeN4 sites in the graphene matrix because of the charge transfer in a model doped graphene/metal heterostructure. By screening a number of face-centered cubic metal substrates using the computational hydrogen electrode approach, we predict Cu as a promising support that results in the theoretical ORR overpotential of the hybrid system that is lower than that of the pure Pt(111) surface. We also determine that Cu exhibits strong adhesion to the FeN4-doped graphene that should improve stability of the catalytic system in aqueous media. Overall, the obtained results demonstrate that nanostructuring or alloying of M–N–C materials with other metals is a viable strategy to enhance the activity and stability of ORR PGM-free catalysts.