Single-atom alloy structure and unique bonding properties of Au₁₀₄Ag₄₀(PET)₆₀ nanoclusters

The detailed characterization of AuAg alloy nanoclusters is essential to guide the discovery of species ideal for applications in various fields including catalysis and biomedicine. This work presents structural analysis of the Au₁₀₄Ag₄₀(PET)₆₀ species through X-ray absorption spectroscopy (XAS). First, XAS fitting is utilized to model the distribution of Au and Ag atoms within the structure. Our proposed model assigns Ag atoms to the vertex sites of the second shell of the metal core, as well as the outermost staple sites. This distribution reveals Au₁₀₄Ag₄₀(PET)₆₀ to be a Ag single-atom alloy. The proposed model shows outstanding agreement with the coordination number values derived from XAS. XAS near-edge analysis is employed to investigate the alloy bonding interactions between Au and Ag. Substantial d-electron transfer from Au to Ag is observed in this sample, beyond the magnitude of previously studied AuAg NCs. This work enhances the understanding of the structure-property relationship of AuAg alloy NCs, offering insights which can be applied to other large NCs and even NPs. These insights will in turn aid the discovery of new materials for use in various applications.