Multivalency iodine doped TiO2: preparation, characterization, theoretical studies, and visible-light photocatalysis.

Multivalency iodine (I(7)+/I(-)) doped TiO(2) were prepared via a combination of deposition-precipitation process and hydrothermal treatment. The as-prepared samples were characterized by X-ray diffraction, transmission electron microscopy, Brunauer-Emmett-Teller surface area, UV-vis diffuse reflectance spectra, X-ray photoelectron spectroscopy, surface photovoltage spectroscopy, and electric-field-induced surface photovoltage spectroscopy. The electronic structure calculations based on the density functional theory revealed that upon doping, new states that originated from the I atom of the IO(4) group are observed near the conduction-band bottom region of TiO(2), and the excitation from the valence band of TiO(2) to the surface IO(4-) is responsible for the visible-light response of the I-doped TiO(2). The as-prepared I-doped TiO(2) showed high efficiency for the photocatalytic decomposition of gaseous acetone under visible light irradiation (lambda > 420 nm). A possible mechanism for the photocatalysis on this multivalency iodine (I(7)+/I(-)) doped TiO(2) under visible light was also proposed.