Generation of silver titania nanoparticles from an Ag–Ti alloy via picosecond laser ablation and their antibacterial activities

Abstract

In this work, a bulk Ti/Ag alloy was used, for the first time, to produce Ag–TiO₂ compound nanoparticles using picosecond laser ablation in deionised water. Spherical Ag–TiO₂ compound nanoparticles with an average size of 31 nm were produced. They were characterised using UV-VIS spectrometry, transmission electron microscopy (TEM), High-Angle Annular Dark-Field-Scanning Transmission Electron Microscopy (HAADF-STEM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS) and X-ray Diffraction (XRD) methods to identify the nanoparticle size distribution, morphology, chemical composition, phase and surface properties. It was found that Ag-doped TiO₂ nanoparticles were produced. The optical absorption spectra of the Ag–TiO₂ compound nanoparticles shifted to longer wavelengths. The antibacterial activity of the Ag–TiO₂ compound nanoparticles against Gram-negative Escherichia coli (E. coli) bacteria was examined and compared with those using laser generated Ag and TiO₂ nanoparticles and distilled deionised water (as the control). It was found that the antibacterial activity of the Ag–TiO₂ compound nanoparticles was better than laser generated TiO₂ nanoparticles and chemically produced Ag nanoparticles, and was almost as good as laser generated Ag nanoparticles while Ag–TiO₂ was used at a much lower Ag concentrations. The reason behind this is discussed.