Ab Initio Study on Doped Cu138X2 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 nitrate‐to‐ammonia electroreduction (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) bimetallic electrocatalysts for nitrate reduction to ammonia, 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. Additionally, 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 Cu‐based 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.