Surface modification of sol gel TiO2 surface with sputtered metallic silver for Sun light photocatalytic activity: Initial studies

Photocatalysis phenomena in TiO2 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 TiO2 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 TiO2 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 TiO2 thin films, (ii) the surface work function of TiO2 thin films is modified by the silver as revealed by Kelvin probe measurements and (iii) the PCA of silver modified TiO2 thin films is higher in comparison with unmodified surface. An attempt has been made to explain the higher activity of the surface modified Ag/TiO2 thin film photocatalyst through the plasmon assisted photocatalytic process. The present study clearly establishes the view that surface modification of TiO2 is a viable approach towards achieving an efficient sun light photocatalyst.

► The surface work function of sol- gel TiO2 is modified with sputter deposited metallic silver.
► The surface work function is measured by Kelvin probe technique.
► Metallic silver enhances the photocatalytic efficacy of sol gel TiO2 thin films at UV wavelengths.
► Silver – TiO2 system has a high Photocatalytic efficacy with sun light; possible reason is Plasmon fields assist in separating the light generated electron-hole pairs.