Electrocatalytic nitrate ( \({\rm{N}}{{\rm{O}}_3}^ -\) ) reduction to ammonia (NH3) offers a viable approach for sustainable NH3 production and environmental denitrification. Copper (Cu) possesses a distinctive electronic structure, which can augment the reaction kinetics of \({\rm{N}}{{\rm{O}}_3}^ -\) and impede hydrogen evolution reaction (HER), rendering it a promising contender for the electrosynthesis of NH3 from \({\rm{N}}{{\rm{O}}_3}^ -\) . Nevertheless, the role of Cu2O in copper-based catalysts still requires further investigation for a more comprehensive understanding. Herein, the Cu2O/Cu(OH)2 heterostructures are successfully fabricated through liquid laser irradiation using CuO nanoparticles as a precursor. Experimental and theoretical researches reveal that Cu2O/Cu(OH)2 heterostructure exhibits enhanced electrocatalytic performance for \({\rm{N}}{{\rm{O}}_3}^ -\) to NH3 because Cu(OH)2 promotes electron transfer and reduces the valence state of Cu active site in Cu2O. At −0.6 V (vs. reversible hydrogen electrode (RHE)), the NH3 yield reaches its maximum at 1630.66 ± 29.72 \({\rm{\mu g}} \cdot {{\rm{h}}^{ - 1}} \cdot {\rm{m}}{{\rm{g}}_{{\rm{cat}}}}^{ - 1}\) , while the maximum of Faraday efficiency (FE) is 76.95% ± 5.51%. This study expands the technical scope of copper-based catalyst preparation and enhances the understanding of the electrocatalytic mechanism of \({\rm{N}}{{\rm{O}}_3}^ -\) to NH3.
