Structure-Activity Relationships of the Structural Analogs Au₈Cu₁ and Au₈Ag₁ in the Electrocatalytic CO₂ Reduction...

Owing to the significant attention directed toward alloy metal nanoclusters, it is crucial to explore the relationship between their structures and their performance during the electrocatalytic CO₂ reduction reaction (eCO₂RR) and discover potential synergistic effects for the design of novel functional nanoclusters. However, a lack of suitable analogs makes this investigation challenging. In this study, we synthesized a well-defined pair of structural analogs, [Au₈Cu₁(SAdm)₄(Dppm)₃Cl]²⁺ and [Au₈Ag₁(SAdm)₄(Dppm)₃Cl]²⁺ (Au₈Cu₁ and Au₈Ag₁, respectively), and characterized them. Single-crystal X-ray diffraction analysis revealed that Au₈M₁ (M=Cu/Ag) consists of a tetrahedral Au₃M₁ core capped by three (Dppm)Au staples, one Au₂(SR)₃ staple, one lone SR ligand, and a terminal Cl ligand. Ag and Cu were doped at the same site in the Au₈M₁ nanoclusters, which has rarely been reported. Au₈Cu₁ exhibited a significantly higher CO Faradaic efficiency (FE_CO; ~82.2 %) during eCO₂RR than that of Au₈Ag₁ (FE_CO; ~33.1 %). Density functional theory calculations demonstrated that *COOH is the key intermediate in the reduction of CO₂ to CO. The formation of *COOH on Au₈Cu₁ is more thermodynamically stable than on Au₈Ag₁, and Au₈Cu₁ shows a smaller *CO formation energy than that on Au₈Ag₁, which promotes the reduction of CO₂. We believe that the structural analogs Au₈Cu₁ and Au₈Ag₁ offer a suitable template for the in-depth investigation of structure-property correlations at the atomic level.