Photoreduction of Dye with Noble Metal Gold Permeated with Metal Oxide Titania.

Photoactive degradation of textile malachite green (MG), methylene blue (MB) dyes has been permeated on metal oxide TiO₂ nanoparticles under sunlight. Semiconductor photocatalysis is a promising method for removal of toxic chemicals from wastewater produced by industry. Due to tunable bandgap, TiO₂ among various semiconductor studied mostly. Large band gap (UV active) and recombination of exciton in TiO₂ less active in photo degradation. Noble metals such as gold nanoparticles deposited on TiO₂ surface increased the optical activity and to shift optical response to visible region. Degradation detail has been carried out by characterisation such as XRD, UV-Vis, PL, TEM, and SEM for MG and MB textile dyes under sunlight irradiation. UV-visible absorption spectra and PL spectra shows that photo-response of as prepared sample is extended from UV to visible region. PL intensity decreases with increases in concentration of Au nanoparticles, decreases in intensity in optical spectra of Au-TiO₂ composites shows that charge transfer process dominates. Au-TiO₂ plays an essential role in enhancing photocatalytical activity. Decolorization optimization depends on catalyst concentration, Dye concentration, light intensity and, irradiation time.