Preparation Of TiO₂ Thin Films On Glasses And Their Sterilizing Capability

Nano-materials and its technology is the branch of Nano science and technology (Nano-ST). It is dynamic and is very abundant to study content. As typical thin solid film, TiO₂ thin films are a frontier branch of science that are also researched extensively and applied on industry variedly because of the performance of the films. Recently, There has been a growing interesting in new methods to prepare thin film at ambient temperature in aqueous solution, as they are expected to develop novel processing method and manufacturing process, which are low cost and environmentally friendly. In the present work, we have prepared TiO₂ thin films on different substrates from a (NH4)2TiF6 aqueous solution upon addition of boric acid by liquid phase deposition (LPD) method under the ambient temperature. The as-prepared TiO₂ thin films were characterized by X-ray diffraction·(XRD) patterns and thermogravimetry (TG), Transmission Electron Microscope (TEM), scanning electron micrographs (SEM) and X-ray photoelectron spectroscopy (XPS). The molar ratio of ammonium hexauorotitanate (IV) solution and boric acid was 1:3, Powder X-ray diffraction patterns indicated that the deposited films only consisted of anatase particles, because of their different thicknesses, and films showed reflection-interference colors.The S. Aureus and E. Coli sterilizing tests of the TiO₂ thin films showed that the films have a strong sterilizing capability. Through characterization, experiencing heat treatment under 400℃for 1h the films with the thickness of 250nm have better sterilizing capability, and compared with power TiO₂ nano-materials, the films have 23 more times effects in the sterilization of the S. Aureus. Under the illumination of the Ultraviolet light from natural light, the TiO₂ thin films can spontaneously decompose positive-negative, electron e- and cavity h+, which can form the electron-cavity, the cavities oxidize the OH- and H2O which are absorbed on the surfaces of the TiO₂ thin films to·OH, O₂·^- ,·OOH and H₂O₂, using the oxidizing activity, they can quickly decompose the organisms. When S. Aureus and E. Coli were illuminated in the presence of TiO₂ thin films, with the decomposition of the cell wall and the cell membrane of the bacteria, the leakage of intracellular molecules will result in a change in the cell viability. These results imply that TiO₂ thin film photo-catalysts have excellent sterilizing activity.