Preparation, Modification Of TiO₂ Films And Their Photocatalytic Performance Study

With worsening of human living environments caused by the rapid growth of global economy, green chemistry has become a certain important factor for sustainable development. Photo-catalysis, as one of the new green technology, has been extensively researched over the past three decades, and many kinds of photo-catalytic materials have been developed. As a typical photo-catalyst, TiO2, which is of low prices, non-toxicity chemical-stability and relatively easy to prepare, has the priority to be applied practically to the degradation of pollutants and solar utilization.In this work, a novel titanium dioxide nanoparticle films coating on glass substrate were prepared by using colloidal silica as a dispersant and binder. This coating is different from the traditional TiO2 sol-gel coating and has not reported previously. AgNPs were implanted uniformly into the porous film to improve the photocatalytic activity, using photochemical deposition and pulse electrochemical deposition methods. The photocatalytic activity of the coatings on glass was evaluated by degradation of MB under a mercury UV lamp.Different samples were prepared by varying experimental conditions, including time of photochemical deposition, heat-treatment temperature in photochemical deposition method and pulse times, off time, current density and annealing temperature in pulse electrochemical deposition method. The UV-visible spectrometer, X ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X ray photoelectron spectroscopy (XPS) technique were utilized to characterize the films on glass. The results indicated that the thickness of the photocatalytic film prepared by colloidal slurry coated on glass or FTO substrates was about 3μm; the TiO2 film prepared by slurry method exhibited much higher activity than the traditional alkoxide sol-gel method, approximately by a factor of 2. The experimental results also showed that excellent photocatalytic activities with the degradation efficiency over 95% were achieved for:1) The Ag/TiO2 film prepared by photoreduction in mercury UV lamp for 1h and subsequently annealed at 300℃.2) The Ag/TiO2 film prepared by electricochemical deposition with 300 10mA cm-2 impulse for 0.1s with a 0.5 s off time and subsequently annealed at 200℃.