Highly active Fe2O3-doped TiO2 photocatalyst for degradation of trichloroethylene in air under UV and visible light irradiation: Experimental and computational studies

•0.1% Fe2O3-doped TiO2 shows the highest activity for TCE photooxidation.•The photocatalytic activity decreases with treatment temperature between 100 and 400 °C.•Photocatalysts band gaps decrease with increasing Fe2O3 contents.•DFT calculations predict the band gap decline.•Fe2O3-doped TiO2 photocatalysts are active in the visible light.

0.0–5.0 wt% Fe2O3-doped TiO2 photocatalysts were synthesized by an ultrasonic-assisted co-precipitation method and used for degradation of 500 ppm trichloroethylene (TCE) in air. The photocatalysts were treated at 100–400 °C and characterized by high resolution transmission electron microscopy (HRTEM), powder X-ray diffraction (XRD), BET surface area, and Raman, UV–vis, and photoluminescence (PL) spectroscopies. For the samples treated at 100 °C, XRD patterns show no significant peaks, while HRTEM micrographs indicate crystalline structures and diffraction patterns and Raman spectra reveal wide and weak peaks of anatase TiO2. As 0.1 wt% Fe2O3 is added to TiO2, the surface area increases by a factor of 1.87 and reach to 448 m2/g. UV–vis analyses indicate that, as the Fe2O3 content of the samples increases, the band gap energies decrease from 3.22 eV for the pure TiO2 to 2.60 eV for 5.0 wt% Fe2O3-doped TiO2. Density functional theory simulations show that, when Fe3+ is doped into or FeO, Fe2O3 or Fe4O6 is adsorbed on anatase TiO2, the bad gap reduces and the iron oxide–TiO2 show photocatalytic activity in visible light region. The synthesized TiO2 showed about two times higher photocatalytic activity for TCE removal than that of Degussa P25. Moreover, 0.1 wt% Fe2O3-doped TiO2 sample dried at 100 °C showed a maximum photocatalytic TCE conversion of about 97% with minor amounts of CO as a hazardous byproduct. As the treatment temperature of the samples increase, the photocatalytic activity declines. Significant photocatalytic degradation of TCE was also observed for the Fe2O3-doped TiO2 samples, under visible light irradiation.

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