Charge separation and catalytic activity of Ag@TiO2 core-shell composite clusters under UV-irradiation

Photocatalytic properties of Ag@TiO2 composite clusters have been investigated using steady state and laser pulse excitations. Photoexcitation of TiO2 shell results in accumulation of the electrons in the Ag core as evidenced from the shift in the surface plasmon band from 460 to 420 nm. The stored electrons are discharged when an electron acceptor such as 02, thionine, or C-60 is introduced into the system. Charge equilibration with redox couple such as C-60/C-60(.-) shows the ability of these core shell structures to carry out photocatalytic reduction reactions. The charge separation, charge storage, and interfacial charge-transfer steps that follow excitation of the TiO2 shell are discussed.