Stabilizing Cu δ+ Species via Ni,Co Comodification for Promoted Electrocatalytic Nitrate Reduction

Electrochemical nitrate reduction reaction (NO3RR) for ammonia (NH3) production is considered as a sustainable alternative to the Haber–Bosch process due to its renewable nature and environmental friendliness. Nevertheless, the sluggish reaction kinetics of the NO3RR severely limits the NH3 yield and Faradaic efficiency, hindering its practical applications. Copper (Cu) catalysts, although widely employed, suffer from *NO2 accumulation and an insufficient active hydrogen (*H) supply, resulting in unsatisfactory NO3RR performance. Herein, to refine the catalytic properties of Cu-based catalysts, a robust Ni,Co-codoped CuOx (Ni,Co-CuOx) nanorod catalyst is designed, which would be in situ reconstructed into stable Ni,Co–Cu/CuOx hybrids during NO3RR. Experimental and theoretical results reveal that Ni,Co codoping effect synergistically stabilizes Cuδ+ species through Ni/Co–O–Cu bonds and maintains the Cu/CuOx structure, which acts as the main active center for NO3RR. Meanwhile, Ni,Co codopants accelerate *H desorption, as well as suppress hydrogen evolution side reaction, leading to a favorable balance between *H supply and intermediate adsorption. Combining the above advantages, the Ni,Co-CuOx catalyst delivers an ultrahigh NH3 yield rate of 130.64 mg h–1 cm–2 with a Faradaic efficiency of 98.53% under ampere current densities. This work innovatively proposes a strategy for immobilizing Cuδ+ species and offers new insights into stable catalyst design for NO3RR. The Ni,Co-CuOx electrocatalyst converts waste nitrate to ammonia with superior performance, offering a low-carbon, sustainable alternative to the Haber–Bosch process.