Papers by Author: Xiang Zhong Li

Abstract: Titanium dioxide (TiO2) nanotubes have been reported one decade ago and have proven to be of a great interest in photocatalytic water splitting, as well as gas sensing and anti-bacterial/cancer treatment. This paper presents an overview on general preparation approaches (chemical treatment, template method and anodic oxidation) of tubular TiO2 nanoarchitectures and their characterization. Current applications of the nanotubes as photocatalysts are also reviewed.

Abstract: In the present work, TiO2 and Ag-TiO2 catalysts were prepared by an ultrasonic assisted sol-gel method. The physico-chemical characteristics studies of the newly synthesized catalysts were carried out by XRD, TEM, EDX, XPS, UV-Visible absorption spectra and an optical ellipsometry. In order to find out the optical absorption properties of the catalysts, theoretical simulations have been carried out by using the Tauc-Lorentz oscillator model. Photodegradation and mineralisation of the chlorophenols were confirmed by the HPLC and TOC measurements. The rate of a mineralisation trend was observed in the order of P < 2-CP < 2,4-DCP < 2,6-DCP < 4-CP < 2,4,6-TCP by using the Ag-TiO2 catalyst. The concentration of the main aromatic intermediate products was considerably lower for the Ag-TiO2 photocatalysts than for pure TiO2. This experiment demonstrated that the presence of Ag on TiO2 catalysts could enhance the photocatalytic oxidation of chlorophenols in an aqueous suspension. It was found that the degradation of the chlorphenols by these catalysts followed the pseudo- first order kinetic model.