Photophysical properties of nanosized metal-doped TiO2 photocatalyst working under visible light

Abstract

Metal-doped TiO2 nanoparticles were prepared by the sol-gel and hydrothermal synthesis methods. The estimated quantum yields (QYs) of Pt/Cr-doped TiO2 nanoparticles was ca. 0.3 %. Cr-, Co- and N-doped TiO2 showed the photocatalytic activity for IPA degradation to CO2, but only Cr-doped TiO2 produced H-2 photocatalytically in the presence of methanol-water aqueous solution under visible light (lambda > 420 nm). Thus, in the case of Pt/Co-doped TiO2, the electron excited to the conduction band has a sufficient reduction potential to reduce H+ ion, but hole in the valence band has lower oxidation potential than required for CH3OH degradation to CO2. Therefore, Cr-, Co- and N-doped TiO2 show the different activity for the photocactalytic reaction of gases and solution phases. The results of the calculated electronic structure and experimental optical properties are correlated to schematically to describe the possible mechanism of the photocatalytic behavior of the system under study.