Enhanced photocatalytic characteristics by Ag-sensitized TiO2 photocatalysts with mixed phases

The Ag-sensitized TiO2 photocatalysts with various contents of Ag were fabricated by a facile sol-gel method. The Ag nanoparticles with an average diameter of only a few nanometers distributed uniformly over the TiO2 surface. Their presence resulted in suppressed recombination and more effective utilization of the visible-light radiation through surface plasmon resonance. However, excess Ag nanoparticles led to higher recombination rates, reduced surface area, and thereby lower photocatalytic activity. Comparative study on the photocatalytic performance of the photocatalysts without and with various Ag loadings was systematically carried out. The moderate reduction of Ag nanoparticles by an appropriate surface treatment condition to increase the area for dye adsorption was favorable to photodegradation. By double calcinations, mixed phases of anatase and rutile were obtained, which exhibited better performance than single phase. The synergistic effect of Ag nanoparticles, mixed phase TiO2 and high surface area has qualified the Ag-sensitized TiO2 nanocomposites as highly promising photocatalysts.