An Efficient Visible-Light-Sensitive Fe(III)-Grafted TiO2 Photocatalyst

We have prepared a TiO2-based novel visible-light-sensitive photocatalyst, in which Fe(III) species were grafted on a rutile TiO2 surface (denoted as Fe(III)/TiO2). With use of X-ray absorption fine structure analysis, the grafted iron species were determined to be in the 3+ state and adopt an amorphous FeO(OH)-like structure. Fe(III)/TiO2 displayed optical absorption in the visible light range over 400 nm, which was assigned to the interfacial charge transfer from the valence band of TiO2 to the surface Fe(III) species. Its photocatalytic activity was evaluated by the decomposition of gaseous 2-propanol under visible light (400−530 nm), which revealed a high quantum efficiency (QE) of 22%. Monochromatic light experiments indicated that the effective wavelength region was extended as far as 580 nm while maintaining a QE of greater than 10%. On the basis of the analogy to Cu(II)-grafted TiO2 photocatalyst (Irie, H.; et al. Chem. Phys. Lett. 2008, 457, 202), we speculate that the high performance of the present photocatalyst is derived from the photoproduced holes that are generated in the valence band of TiO2 and contribute to the oxidative decomposition of 2-propanol, and the catalytic reduction of oxygen (presumably multielectron reduction) by photoproduced Fe(II) species on TiO2.