Rational Design of a New N-modified Nickel Foam with Superior Electrocatalytic Conversion of Nitrate to Ammonia

Electrocatalytic reduction of aqueous nitrate to ammonia has emerged as a sustainable and practical approach in combining water treatment and ammonia fertilizer synthesis. In this study, we developed a new N-modified NiF from commercial NiF. Our unique approach induces key characteristics such as high electrochemical surface area (ECSA) and N-rich surface. These induced properties lead to superior performance for the modified NiF compared to the pristine NiF in electrocatalytic nitrate reduction reaction (NO₃RR) to ammonia. The modified NiF achieves a high current density of 2.0 A cm^-2 at a potential of only 0.067 V vs RHE with a Faradaic efficiency (FE) of 92.7% and a yield rate of 146 mg h^-1 cm^-2 at elevated temperature. Such an outstanding yield rate is more than 160 times higher than that of commercial NiF. Moreover, the thermal-enhanced electrocatalysis system shows remarkable stability, low interference resistance, and a favorable energy consumption for nitrate reduction reaction. Complementary in situ analyses indicate that the significantly superior relay of active adsorbed *H generated on the surface of modified NiF facilitates the electrocatalytic hydrogenation of N-based species in the process of *NO₃→*NO₂→*NO →*N →*HN →*H₂N →*NH₃. The new strategy aims to provide the rational design of a newly modified structure on the NiF to serve as the future direction for NiF-based materials for practical electrodes with high performance.