Photocatalytic properties of P25-doped TiO2 composite film synthesized via sol-gel method on cement substrate

Abstract

TiO₂ films have received increasing attention for the removal of organic pollutants via photocatalysis. To develop a simple and effective method for improving the photodegradation efficiency of pollutants in surface water, we herein examined the preparation of a P25-TiO₂ composite film on a cement substrate via a sol-gel method. In this case, Rhodamine B (RhB) was employed as the target organic pollutant. The self-generated TiO₂ film and the P25-TiO₂ composite film were characterized by X-ray diffraction (XRD), N₂ adsorption/desorption measurements, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and diffuse reflectance spectroscopy (DRS). The photodegradation efficiencies of the two films were studied by RhB removal in water under UV (ultraviolet) irradiation. Over 4day exposure, the P25-TiO₂ composite film exhibited higher photocatalytic performance than the self-generated TiO₂ film. The photodegradation rate indicated that the efficiency of the P25-TiO₂ composite film was enhanced by the addition of the rutile phase Degussa P25 powder. As such, cooperation between the anatase TiO₂ and rutile P25 nanoparticles was beneficial for separation of the photo-induced electrons and holes. In addition, the influence of P25 doping on the P25-TiO₂ composite films was evaluated. We found that up to a certain saturation point, increased doping enhanced the photodegradation ability of the composite film. Thus, we herein demonstrated that the doping of P25 powders is a simple but effective strategy to prepare a P25-TiO₂ composite film on a cement substrate, and the resulting film exhibits excellent removal efficiency in the degradation of organic pollutants.

Keywords: Cement substrate; Doping; P25-TiO(2) composite film; Photocatalysis; Rhodamine B; Sol–gel method.