Dopant Engineering of Isostructural Metal Nanoclusters for Modulating CO 2 Electroreduction

Achieving atomic‐level insight into how dopants regulate the electrocatalytic CO 2 reduction reaction (eCO 2 RR) of metal nanoparticles is challenging due to the lack of well‐defined, compositionally tunable, and structurally identical model systems. Herein, we report two isostructural nanoclusters: [Au 10 Ag 4 (DPPP) 5 Cl 4 ] 2+ ( Au 10 Ag 4 ) and [Au 9 Ag 2 Cu 3 (DPPP) 5 Cl 4 ] 2+ ( Au 9 Ag 2 Cu 3 ), which differ only in metal composition (Au─Ag vs. Au─Ag─Cu). Together with the isostructural monometallic [Au 14 (DPPP) 5 Br 4 ] 2+ ( Au 14 ), they serve as ideal platforms to elucidate dopant effects on eCO 2 RR. Electrochemical studies reveal that Ag doping ( Au 10 Ag 4 ) suppresses both CO selectivity and activity of Au 14 , whereas further Cu incorporation ( Au 9 Ag 2 Cu 3 ) not only enhances these metrics relative to Au 10 Ag 4 but also surpasses Au 14 . Specifically, Au 9 Ag 2 Cu 3 exhibits an enhanced CO Faradaic efficiency (FE CO , 73.7%−95.5%), exceeding that of Au 14 (63.6%−95.0%) and Au 10 Ag 4 (66.2%−79.5%), and its CO partial current densities were improved by 1.5‐ and 2.6‐fold compared to those of Au 14 and Au 10 Ag 4 , respectively. Theoretical calculations and in situ experiments reveal that Ag─Cu co‐doping lowers the energy barrier for * COOH formation and weakens CO binding, promoting CO 2 ‐to‐CO conversion. In contrast, Ag doping alone raises the energy barrier for * COOH formation and impedes CO desorption, diminishing catalytic activity. These findings provide atomistic insights into dopant‐regulated eCO 2 RR and inspire the rational design of advanced alloy electrocatalysts.