Density Functional Theory Studies of Earth-Abundant Late Transition Metal-Substituted Surface + Subsurface Iron Alloys for Selective Electrocatalytic N₂ Reduction

Ammonia production from the earth-abundant feedstock of N2 is one of the most attractive fields of research. Searching for an alternative iron-based electrocatalyst for direct ammonia synthesis is a challenging process due to the harsh reaction conditions present in the traditional route of the Haber–Bosch process. In the present work using the density functional theory (DFT) calculations, we have systematically investigated the potential of late transition metal (TM = Co, Ni, and Cu) substitution on the surface, subsurface, and surface + subsurface of Fe(110) toward the nitrogen reduction reaction (NRR) and the hydrogen evolution reaction (HER). We demonstrate that a Ni-substituted surface + subsurface catalyst can favor the electrocatalytic ammonia synthesis with the maximum Faradaic efficiency by suppressing the HER compared to the previously reported catalysts for ammonia production. These findings open a way in terms of designing surface + subsurface-substituted alloy catalysts for various catalytic reactions.