Preparation and characterization of visible-light-driven plasmonic photocatalyst Ag/AgCl/TiO2 nanocomposite thin films

The Ag/AgCl/TiO2 nanocomposite thin films are prepared on the pre-coated SiO2 soda-lime glass substrates by a sol–gel method for depositing TiO2 films, and then loaded with Ag/AgCl nanoparticles (NPs) by an impregnating precipitation photoreduction method. The as-prepared composite thin film exhibits a highly visible-light photocatalytic activity for degradation of 4-chlorophenol (4-CP) in water. The photocatalytic mechanism is proposed on the basis of the fact that the Ag NPs are photoexcited due to plasmon resonance, and then charge separation is accomplished by the transfer of photoexcited electrons from the Ag NPs to the TiO2 conduction band and the simultaneous formation of OH radical and Cl0, which cause the photocatalytic degradation of organic pollutants. The proposed mechanism is further confirmed by the detection of hydroxyl radicals. On the other hand, 4-CP can also be oxidized directly by plasmon-induced h+ (or Ag+) on Ag NPs, thereby accelerating the photooxidized Ag NPs back to their initial state. Therefore, the Ag NPs can be rapidly regenerated and the Ag/AgCl/TiO2 system remains self-stability.