Effect of Silver on Plasmonic, Photocatalytic, and Cytotoxicity of Gold in AuAgZnO Nanocomposites

Four different nanocomposites of AuAgZnO with differing compositions of silver and gold were made by solution combustion method where the EDAX analysis gave the exact composition. Nanocomposites were formed as nanospheres. The composites contained bimetallic AuAg particles on the surface of ZnO semiconductor, the interface being silver. The deconvoluted UV–DRS spectra revealed the presence of two plasmons due to Au and Ag. The amount of gold dominates the AuAg indicating the presence of only a thin layer of silver below gold causing a blue-shifted gold plasmon band and red-shifted silver plasmon band in comparison to their pure entity. The intensity of the former gets increased due to interparticle interaction with silver. Presence of excess gold in one sample of the starting materials tends to form amorphous Au 2 O 3 as proved by both EDAX and XPS. The number of oxygen vacancies in ZnO as seen in EPR depends on AuAg metal content effects the photocatalytic degradation of Rhodamine-B and the photocatalytic production of hydrogen. The interparticle interaction of Ag with Au and ZnO also plays a major role in photocatalytic process. An in vitro cytotoxicity study of AuAgZnO nanocomposites on MCF-7 cell lines is compared with the effect of gold alone in AuZnO. The current study revealed that the presence of silver in the bimetallic system suppresses the efficacy of Au and even ZnO. Gold by itself is a powerful cytotoxic nanoagent even with small amount of ZnO, the latter being known for its nontoxicity. It is interesting to note that Ag has a negative role in cytotoxicity but it contributes positively to photocatalysis.