Single Metal Atoms Anchored in Two-Dimensional Materials: Bifunctional Catalysts for Fuel Cell Applications

Single metal atoms doped in two-dimensional materials have attracted particular attention for various catalytic reactions, due to their unique properties beyond metal catalysts. Herein we present density functional theory (DFT) calculations to study a wide range of such systems for oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR) for application in cathode and anode of fuel cell, respectively. We find that the scaling relation of adsorption free energies of relevant ORR intermediates changes in the direction of improved activity. By considering more than 50 combinations, various ORR and HOR candidates are identified with improved catalytic activities compared to the state-of-the-art Pt (111). Particularly, Rh embedded in N-doped graphene is predicted to be markedly active for bifunctional fuel cell catalysis. This work highlights the potential of these systems as new classes of electrocatalysts to maximize the ORR catalytic activity and alleviate the use of precious metals