Preparation of photocatalytic Au-Ag₂Te nanomaterials

A facile approach has been developed for the preparation of various morphologies of Au-Ag₂Te nanomaterials (NMs) that exhibit strong photocatalytic activity. Te NMs (nanowires, nanopencils, and nanorice) were prepared from TeO₂ in the presence of various concentrations (16, 8, and 4 M) of a reducing agent (N₂H₄) at different temperatures (25 and 60 °C). These three Te NMs were then used to prepare Au-Ag₂Te NMs by spontaneous redox reactions with Au³⁺ and Ag⁺ ions sequentially. The Au-Ag₂Te nanopencils exhibit the highest activity toward degradation of methylene blue and formation of active hydroxyl radicals on solar irradiation, mainly because they absorb light in the visible region most strongly. All three differently shaped Au-Ag ₂Te NMs (10-μg mL^-1) provide a death rate of Escherichia coli greater than 80 % within 60-min, which is higher than that of 51 % for commercial TiO₂ nanoparticles (100-μg mL^-1). Under light irradiation, the Au NPs in Au-Ag₂Te NMs enhance the overall photo-oxidation ability of Ag₂Te NMs through faster charge separation because of good contact between Ag₂Te and Au segments. With high antibacterial activity and low toxicity toward normal cells, the Au-Ag₂Te NMs hold great potential for use as efficient antibacterial agents.