Study on preparation and photocatalytic properties of M/TiO₂ composite film by two-step mechanical ball milling

The composite films of M/TiO₂ (M = Al, Sn, Zn, Ti) were prepared by the two-step mechanical ball milling. The microstructure and phase composition of the composite coating were analyzed by the optical microscopy (OM) and X-ray diffraction (XRD), the photocatalytic properties of the composite films were determined, and the effects of the transition layer materials and milling time on the photocatalytic properties of the composite films were investigated. The results show that, the crystal structure of the TiO₂ powders does not change significantly during the ball milling process, and the TiO₂ powders still maintain the good photocatalytic activity. The metal transition layers of Al, Sn, and Zn will significantly weaken the photocatalytic activity of the composite films, while Ti is an ideal metal transition layer for the composite film, and the prepared Ti/TiO₂ composite films have the excellent photocatalytic properties. With the prolongation of the second step milling time, the photocatalytic properties of the Ti/TiO₂ composite films are gradually reduced, which is caused by the decrease of the TiO₂ content on the surface of the second film.