Theoretical Screening of Efficient TM/GaN Single-Atom Catalysts for Electroreduction of Nitrate to Ammonia

The electrocatalytic nitrate (NO₃^–) reduction reaction (NO₃RR) represents a promising strategy for synthesizing ammonia (NH₃) under milder conditions, providing an environmentally friendly alternative to the Haber–Bosch process. However, current electrochemical NO₃RR catalysts are limited in terms of selectivity and catalyst stability. Herein, novel efficient single-atom catalysts for selective and active electrochemical reduction of nitrate to ammonia, based on transition metals doped on a gallium nitride (GaN) monolayer, are investigated by using density functional theory calculations. Among 18 candidates, V/GaN and Ru/GaN are identified as the most effective catalysts, demonstrating low limiting potentials of –0.39 V and –0.46 V, respectively. Ab initio molecular dynamics simulations further confirm the kinetic stability of these catalysts, with the structures of V/GaN and Ru/GaN remaining stable after 5 ps at 500 K. Our findings suggest that V/GaN and Ru/GaN are promising electrocatalysts for efficient and selective NO₃RR to NH₃, warranting further experimental validation.