RESUMEN
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 (FECO; ~82.2 %) during eCO2RR than that of Au8Ag1 (FECO; ~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.
RESUMEN
The precise tuning of cluster composition helps us to understand the relationship between clusters and their properties. In this context, on the basis of [Au4Ag5(SAdm)6(Dppm)2](BPh4) (HSAdm is 1-adamantanethiol, C10H15SH; Dppm is bis(diphenylphosphino)methane, Ph2PCH2PPh2), the control of the internal metal, surface thiol, and surface phosphine ligand was accomplished, with the formations of [Au6.5Ag2.5(SAdm)6(Dppm)2](BPh4), [Au4Ag5(S-c-C6H11)6(Dppm)2](BPh4) and [Au4Ag5(SAdm)6(VDPP-2H)2](BPh4) (HS-c-C6H11 is cyclohexanethiol; VDPP is 1,1-bis(diphenylphosphino)ethylene, (Ph2P)2CîCH2; and VDPP-2H is 1,1-bis(diphenylphosphine) ethane derived from the reduction of VDPP, (Ph2P)2CHCH3). The structures of [Au6.5Ag2.5(SAdm)6(Dppm)2](BPh4) and [Au4Ag5(S-c-C6H11)6(Dppm)2](BPh4) were determined by single-crystal X-ray crystallography (SC-XRD), while that of [Au4Ag5(SAdm)6(VDPP-2H)2](BPh4) was confirmed via ESI-MS measurements. The control of the metal, thiol and phosphine ligand affects the electronic structure and optical properties of the [Au4Ag5(SAdm)6(Dppm)2](BPh4) cluster. Overall, the nanoclusters [Au4Ag5(SAdm)6(Dppm)2](BPh4), [Au6.5Ag2.5(SAdm)6(Dppm)2](BPh4), [Au4Ag5(S-c-C6H11)6(Dppm)2](BPh4) and [Au4Ag5(SAdm)6(VDPP-2H)2](BPh4) provide a chance to explore the effect of regulation of metals and surface ligands on electronic and optical properties.