Insights Into Nitrate‐to‐Ammonia Electrocatalysis on Graphene‐Supported Asymmetric M1N 3 ─M2N 4 Dual‐Atom Catalysts
Shaopeng Xu, Linlin Li, Yan Yan, Wei Li, Jiaojiao Chen, Linda Zhang, Piao Ma, Xunlei Ding, Hao LiABSTRACT
Nitrate (NO 3 − ) pollution threatens aquatic ecosystems and drinking water safety, while electrocatalytic nitrate reduction to ammonia (NO 3 RR) offers a route for pollutant removal and nitrogen recovery. Here, density functional theory calculations were used to screen 100 graphene‐supported asymmetric M1N 3 ─M2N 4 dual‐atom catalysts (M1, M2 = 3 d transition metals) by considering stability, pristine‐site availability, reaction pathways, and ammonia desorption. Single‐H adsorption free energy alone was insufficient to describe competition with the hydrogen evolution reaction in dual‐site systems; *2H and *OH surface states should also be considered when determining catalyst‐specific electrochemical potential windows. NO 3 − mainly adopted side‐on@bridge and side‐on@M1 configurations, leading to site‐dependent pathway branching. Zero or near‐zero U L values often coincide with strong NH 3 binding. NiN 3 ─ZnN 4 ‐P1 and CuN 3 ─CoN 4 ‐P2 displayed balanced profiles, with limiting potentials of −0.29 and −0.23 V and NH 3 desorption free energies of 0.12 and 0.35 eV, respectively. These results provide theoretical guidance for evaluating and designing asymmetric dual‐site NO 3 RR catalysts by jointly considering site availability, pathway thermodynamics, and product release.