Ab Initio Study on Doped Cu ₁₃₈ X ₂ Nanoparticles With Dispersed Surface‐Active Sites for Enhanced Electrocatalytic Nitrate Reduction to Ammonia

Copper nanoparticles (NPs) exhibit significant potential in electrocatalysis owing to their tunable electronic structure and abundant surface-active sites. However, the multifaceted complexity of Cu-based nanoparticles induced by heteroatom dopants fundamentally limits our ability to decipher the electrochemical nitrate reduction reaction (NO₃RR) mechanism, creating a critical knowledge gap that obstructs the targeted engineering of advanced catalysts with atomic precision. In this study, we employed first-principles calculations to design a series of highly surface-dispersed transition metal-doped Cu₁₃₈X₂ (X = Ag, Au, Pd, Zn, Ni, Pt) bimetallic electrocatalysts for nitrate reduction to ammonia (NH₃), based on the structure of Cu₁₄₀ NPs. Theoretical analysis revealed that Cu₁₃₈Au₂ exhibits significant advantages in NO₃RR, with a remarkably low limiting potential of -0.20 eV. In addition, significant energy barriers were observed for the formation of by-products NO and NO₂ on Cu₁₃₈Au₂, ensuring high selectivity towards ammonia. For Cu-based catalysts, we propose that the *NO₂ → *HNO₂ step is critical and can serve as a descriptor for rapid screening of these catalysts. This study not only provides important insights into the research of Cu NPs as NO₃RR electrocatalysts but also establishes a theoretical foundation for enhancing their catalytic performance through surface modification or compositional tuning.