Improving the Photocatalytic Performance of Fe-Doped Titania Photocatalysts by Modification with Gold Nano-particles for Oxidation of Formaldehyde in Air Under UV and Visible Light

Formaldehyde (HCHO) is one of the critical indoor pollutants. Long-term exposure to HCHO causes physical and mental disorders, so photocatalytic oxidation of formaldehyde should be considered. In this experiment, formaldehyde conversion to harmless gasses is examined.0.4% Au deposited on 0.0–.15% Fe2O3–TiO2 catalyst synthesized by ultrasonic assisted co-precipitation method, was used for photocatalytic oxidation of 400 ppm formaldehyde in air under UV and visible light irradiation at room temperature. Also The photocatalysts were characterized by powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and BET surface area. Significant peaks shown in the photocatalysts XRD patterns imply to the crystalline structures of the catalysts. Also, HRTEM micrographs and Raman spectra indicate crystalline structures. 0.1% Fe2O3– doped TiO2 catalyst has the highest formaldehyde conversion to CO2 under UV irradiation of 57% and the highest surface area of 432m2/g. As 0.4% Wt Au is added to the 0.1% Fe2O3–doped TiO2, the formaldehyde conversion enhanced to 88% under UV irradiation while in visible light the photocatalyst shows 41% conversion. When Au deposited on the surface of Fe-doped TiO2, the electron-hole recombination rate has been effectively inhibited, and the high oxidation activity of Au nanoparticles significantly enhances the photocatalyst activities. As Fe2O3 content of the catalysts increases, the band-gap energies decreases, for instance, from 3.22 eV for the pure TiO2 to 3.01 eV for 0.1% Fe2O3 – doped TiO2. Density functional theory simulations show that, when Fe3+ is doped into TiO2, the band-gap reduces and extends the light absorption of TiO2 into the visible region. Furthermore, in humid air, the conversion reduces from 88% to 61% for Au- 0.1% Fe2O3-TiO2 photocatalyst.

Keywords:

photocatalyst , photocatalytic activity , photo oxidation , formaldehyde , conversion