Study of the visible light activity of Pt and Au-TiO2 photocatalysts in organic pollutants degradation

Pt-TiO2 and Au-TiO2 photocatalysts were prepared by noble metalphotodeposition on sulfated TiO2. It was observed that optical absorption, oxidation state andparticle size of the metallic species (Pt or Au) play an important role in the TiO2 photocatalyticactivity under visible-light irradiation. Photocatalytic activity of the bare TiO2 powder in thephenol and methyl orange degradation increased with the sulfation and metal addition.The highest degradation rate under UV-Visible and visible light irradiation was obtained onPt-S-TiO2 photocatalyst; this is mainly due to the optical properties of TiO2 induced byplatinization and also to the good distribution and low Pt particles size. It was also found thatthis catalyst has a good stability after two cycles of reaction in the phenol photodegradationunder UV-Visible light irradiation. The Pt-S-TiO2 photocatalyst was also active under solarlight and under the environmental conditions of the city of Tunja (Boyaca), Colombia.