Surface modification of sol gel TiO <inf>2</inf> surface with sputtered metallic silver for Sun light photocatalytic activity: Initial studies

Photocatalysis phenomena in TiO 2 have been under intense investigation for its potential applications in pollution abatement and in production of hydrogen for green energy. Present study shows that surface modification is a potential technique to achieve efficient and stable plasmonic assisted sun light driven photocatalyst with TiO 2 thin films. A few layers (of different thicknesses) of metallic silver have been deposited (by DC magnetron sputtering technique and subsequently annealed) on the surface of sol-gel processed and spin coated TiO 2 thin films. The photocatalytic activity (PCA) has been measured with 254 nm, 352 nm and actual sun light excitations; aqueous Rhodamine B (RhB) dye is used to estimate the photocatalytic oxidation. The photocatalytic activity has been expressed as the number of RhB molecules oxidized for a given photon flux at the excitation wavelength; also rate constants have been evaluated. It is observed that (i) silver exists in the metallic state on the surface of TiO 2 thin films, (ii) the surface work function of TiO 2 thin films is modified by the silver as revealed by Kelvin probe measurements and (iii) the PCA of silver modified TiO 2 thin films is higher in comparison with unmodified surface. An attempt has been made to explain the higher activity of the surface modified Ag/TiO 2 thin film photocatalyst through the plasmon assisted photocatalytic process. The present study clearly establishes the view that surface modification of TiO 2 is a viable approach towards achieving an efficient sun light photocatalyst. © 2012 Elsevier B.V. All rights reserved.