Fe-Co-Ni Ternary Single-Atom Catalysts for Efficient Electrochemical Nitrate Reduction

Electrochemical nitrate reduction offers a sustainable route to water remediation and ammonia synthesis, yet its activity and selectivity are fundamentally limited by scaling relationships of single-metal active sites. Here, we report a non-equilibrium strategy that enables the construction of atomically dispersed FeCoNi trimetallic single-atom catalyst. In-situ experiments and theoretical calculations reveal that synergistic metal centers stabilize nitric oxide and promote its hydrogenation with a reduced activation barrier. The catalyst achieves an excellent Faradaic efficiency of 99.4% and a yield rate of 650 µmol h^-1 cm^-2 in 1 M KOH with 100 mM nitrate, placing it among the top-performing multi-metal single-atom catalysts. Integration into a zinc-nitrate battery enables simultaneous nitrate removal, sustained electricity generation, and continuous ammonia production. This work provides a general strategy for constructing multi-metal active sites for nitrate valorization and ammonia synthesis.