Computational Investigation of FeCuN Co-doped Graphene as a Bimetallic Electrocatalyst for Oxygen Reduction Reaction

The development of cost-effective and efficient electrocatalysts for oxygen reduction reaction (ORR) is crucial for energy conversion technologies such as fuel cells and metal–air batteries. To date, platinum remains the benchmark ORR catalyst; however, its high cost and scarcity motivate the search for alternative materials. In this study, we present a density functional theory (DFT) investigation of iron-copper-nitrogen (FeCuN) co-doped graphene (FeCuNn@G) as a potential non-precious-metal ORR electrocatalyst. The electrocatalytic performance of FeCuN8@G is evaluated and compared with monometallic iron-nitrogen co-doped graphene (FeN4@G) and copper-nitrogen co-doped graphene (CuN4@G) systems. The ORR mechanisms are explored through thermodynamics including Gibbs free energy diagrams, limiting potentials (UL), and Bader charge analysis, and metal–oxygen bond distances. Among several configurations of FeCuN8@G, FeCuN8@G-4, and FeCuN8@G-5 substrates with FeN4 active sites exhibit UL of 0.89 and 0.71 V, respectively, which are comparable to Pt (111). The co-presence of Cu improves catalytic activity at the Fe site in specific configurations, though the influence appears geometric rather than electronic. These findings provide valuable insight into the design principles of bimetallic ORR electrocatalysts.