Visible light active TiO2-ZnO composite films by cerium and fluorine codoping for photocatalytic decontamination

The visible light active Ce/F codoped TiO2-ZnO composite films with a bad gap of 1.82 eV were successfully prepared though a simple sol-gel method. Experimental results indicated that the composite films showed excellent photocatalytic performance towards photocatalytic oxidation of organic pollutants including formaldehyde, acid naphthol red (ANR) and methyl green (MG). The catalysts were characterized by photoluminescence (PL) spectra, UV-vis diffraction reflectance absorption spectra (DRS), X-ray diffraction (XRD), differential thermal analysis-thermogravimetry (DTA-TG), field emission scanning electron microscopy (FE-SEM) equipped with energy-dispersive spectroscopy (EDS), and N-2 adsorption/desorption isotherms. The DRS and PL spectra results showed that multi-modification not only induced strong visible light absorption but also reduced the recombination rate of electron-hole pairs. The DTA-TG and XRD results indicated that the crystal type of the TiO2-based catalyst was mostly stabilized in anatase. The FE-SEM and BET surface area results revealed that the nanocrystalline Ce/F codoped TiO2-ZnO composite samples with the larger specific surface area were composed of smaller nanoparticles compared to pure TiO2. The mechanism of the enhanced photocatalytic activity was discussed in this study. (C) 2015 Elsevier Ltd. All rights reserved.