Au Decorated Mesoporous TiO2 as a High Performance Photocatalyst towards Crystal Violet Dye

Sol-gel derived TiO2 was prepared and decorated with Au nanoparticles by photo deposition technique and examined by means of TEM, XRD, EDX, DRS, and BET-BJH analyses. The band gap was related to the Au decorated TiO2 (Au/T) and the synthesized plain TiO2 were obtained from DRS curves by 3.07 and 3.2 eV. The Au/T showed an enhanced visible light photocatalytic activity towards the Crystal violet (CV) dye in comparison to the plain TiO2 because of surface plasmon resonance phenomenon of the gold nanoparticles. A cooperative working mechanism involving the possible photoactivation of gold nanoparticles as well as surface bounded dye was proposed for the photocatalytic performance of Au/TiO2 system. During the decolorization of the CV dye, two reaction pathways including demethylation of amine sites of the chromophore system and breaking of the whole conjugated chromophore skeleton competing each other. The demethylation of amine sites of CV dye took place predominantly through the raid of OH species to the dye N, N-dimethyl groups, in a stepwise manner.