Amorphous Copper‐Coated Crystalline Cobalt Nanowire for Electrocatalytic Nitrate Reduction to Ammonia in Neutral Medium

Abstract The direct electrocatalytic reduction of nitrate (NO ₃ ⁻ ) to ammonia (NH ₃ ) presents an energy‐efficient and promising strategy for wastewater treatment and the nitrogen cycle. However, under neutral conditions, the electrocatalytic process faces the challenge of insufficient active hydrogen (*H) supply and difficulty in hydrogenation of nitrogen‐containing intermediates. Herein, in this work, an amorphous copper‐coated crystalline cobalt nanowire (c‐Co@a‐Cu) catalyst is successfully fabricated for nitrate electroreduction, which achieves a high NH ₃ yield rate (4.63 mg h ⁻¹ cm ⁻² ) and Faradaic efficiency (99.6%) at −0.6 V versus RHE in a neutral medium, outperforming its crystalline counterpart. The high‐resolution HAADF‐STEM and theoretical calculations indicate that amorphous Cu species coating on the Co nanowire surface synergistically enhance NO₃⁻ adsorption via Co‐Cu interactions. The c‐Co@a‐Cu catalyst lowers the energy barrier for *NO ₃ H formation from *NO ₃ , suppresses the hydrogen evolution reaction (HER), and provides abundant reactive hydrogen (*H) to facilitate hydrogenation of nitrogenous intermediates, ultimately accelerating nitrate‐to‐ammonia conversion. Furthermore, a peak power density up to 5.90 mW cm ⁻² and an NH ₃ yield of 277.20 µg h ⁻¹ cm ⁻² have been realized in a homemade Zn‐NO ₃ ^‐ battery, achieving the integration of power output, nitrate treatment, and green ammonia production.