Investigation on the gaseous benzene removed by photocatalysis employing TiO modified with cobalt and iodine as photocatalysts under visible light.

A new type of photocatalysts, nanocrystalline titanium dioxide (TiO) doped with Co and I, were synthesized and modified via the sol-gel method to enhance the utilization of visible light. Herein, mono- and co-doped TiO (i.e. Co-TiO, I-TiO, Co-I-TiO) were employed as the photocatalysts to investigate the photocatalytic performance on gaseous benzene removal. The prepared photocatalysts were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET)-specific surface areas, Raman spectroscopy, UV-visible diffuse reflectance spectroscopy (UV-vis-DRS), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and electrochemical impedance spectroscopy (EIS). Results indicated that both particle sizes and band gaps of TiO were significantly reduced by doping with Co/I. Also, the lattice defects and the specific surface areas of TiO were substantially augmented by adding Co/I because of the increase of oxygen vacancies, especially for Co-I-TiO. Meanwhile, Co and I were distributed on the titanium base with the existence of multivalent states. The benzene treatment capacity of Co-I-TiO, Co-TiO, I-TiO and Pure TiO is 441.46, 424.36, 388.06, and 51.25 μgCH/(g·h), respectively. To sum up, photocatalytic degradation of gaseous benzene could be improved by doping with Co/I because of the extension of catalyst lifetime and light response range covering visible light.