InVO 4-sensitized TiO 2 photocatalysts for efficient air purification with visible light

Abstract

A visible-light-driven InVO 4/TiO 2 mesoporous photocatalyst was prepared by a sol–gel method. The catalyst was characterized by powder X-ray diffraction (XRD), nitrogen adsorption–desorption, transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy, X-ray photoelectron spectra (XPS), ultraviolet photoelectron spectra (UPS), and spin-trapping electron paramagnetic resonance (EPR). Photocatalytic activity of the sample was evaluated by the degradation of volatile organic compounds (VOCs) in air under visible light irradiation (450 nm ≤ λ ≤ 900 nm). Results revealed that the addition of InVO 4 leaded to the visible light response up to ∼540 nm for InVO 4/TiO 2. Moreover, upon visible light irradiation, some superoxide radical anions, such as O 2 − and OH radicals, were generated on InVO 4/TiO 2, leading to the decomposition of VOCs. The high photocatalytic activity towards VOCs (e.g. benzene) was still maintained in the cycle experiments, and the turnover numbers recorded within 12 h work out to be 11.8 mol (produced CO 2) and 6.2 mol (degraded C 6H 6) per mol catalyst. Deactivation of the photocatalyst was not observed during the cycle experiments. It has been confirmed that InVO 4/TiO 2 photocatalyst could be activated by visible light due to the existence of the InVO 4. Based on the energy-band levels of InVO 4 and TiO 2, a photosensitization mechanism of InVO 4/TiO 2 is proposed.