Modification of Titanium(IV) Dioxide with Small Silver Nanoparticles: Application in Photocatalysis

The surface of commercial TiO2 compounds (P25 and ST01) has been modified with Ag nanoparticles induced by radiolysis. On P25, the Ag nanoclusters are very small (1-2 nm) and homogeneous in size while on ST01, two populations of nanoparticles are obtained, small nanoparticles (1-2 nm) and larger ones (mean diameter 7 to 12 nm depending on the silver loading). The photocatalytic properties of Ag-modified TiO2 have been studied for phenol photodegradation in aqueous suspensions under UV and visible light. Their electronic properties have been studied by time resolved microwave conductivity (TRMC) to follow the charge-carrier dynamics. TRMC measurements show that the TiO2 modification (P25 and ST01) with Ag nanoparticles plays a role in charge-carrier separations increasing the activity under UV light. Indeed, Ag nanoparticles act as electron scavengers, decreasing the charge carrier recombination. TRMC measurements show also that more electrons are produced in the conduction band of P25 under UV illumination of Ag-modified P25. Surface modification by silver nanoparticles induces also a modification of the absorption properties of the photocatalyst creating an activity under visible light.