Synthesis of Au doped Ag nanoclusters and the doping effect of Au atoms on their physical and optical properties

Bimetallic noble metal nanoclusters (NCs) are an emerging topic of metal clusters due to their distinguishing characteristics compared to monometallic clusters. Doping of different noble atoms in other clusters is an effective strategy for tailoring their functionalities for specific applications and synergistic effects. Obtaining single-heteroatom doping is desirable but still very challenging to date. Herein, 2,4-dimethylbenzenthiol (2,4-DMBT) protected Ag/Au alloy NCs (ca. 2-3 nm) were synthesized via a wet chemical one-pot process. The effect of the number of Au atoms in Ag NCs on their optical properties and bandgap was investigated. We found that the change of the absorption peak positions of the Ag NCs was influenced by the presence of Au atoms. Besides, we found that the HOMO-LUMO peak has appeared without a significant change in cluster size during synthesis. Ag/Au alloy NCs are characterized by UV-visible spectroscopy, transmission electron microscopy (TEM) and scanning electron transmission microscopy (STEM).