Visible Light Enhanced Fe-I-TiO2 Photocatalysts for the Degradation of Gaseous Benzene

Visible light enhanced mono- and co-doped TiO2 (i.e., Fe/I–TiO2, Fe–I–TiO2) were synthesized via the sol-gel method. The photocatalytic degradation of gaseous benzene by different photocatalysts was evaluated in this study. The morphology and structure of photocatalysts were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Tellerspecific surface areas (BET), Raman spectroscopy, UV–visible diffuse reflectance spectroscope (UV–vis-DRS) and X-ray photoelectron spectroscopy (XPS). Results indicated that Fe/I mono- and co-doped TiO2 are the same anatase as the pure TiO2, but the Fe–I–TiO2 effectively decreased the crystallite size and increased the specific surface area and the lattice distortion caused by oxygen vacancies. Meanwhile, the Fe–I–TiO2 had more surface-bound hydroxyl or chemisorbed oxygen than the pure and Fe/I–TiO2 photocatalysts and a smaller bandgap than pure and Fe/I–TiO2 photocatalysts. The iodine element involving in the Fe–I–TiO2 had various valence states (less than positive pentavalent) and the iron element evenly distributed on the titanium base existed in the trivalent form. Thus, the Fe–I–TiO2 exhibits the most excellent photocatalytic performance (674.55  μg C6H6/(g·h) and the removal efficiency of gaseous benzene can be reached at59.38%, which is higher than the pure TiO2 (4.72%), Fe–TiO2 (37.35%) and I–TiO2 (45.29%).