Photocatalytic of TiO_2-SiO_2 Thin Films Co-Doped with Fe~(3+) and Thio-Urea in the Degradation of Formaldehyde by Indoor and Outdoor Visible Lights

摘要

In this work the photocatalytic activity of TiO_2-SiO_2 thin films co-doped with Fe~(3+) and thio-urea in the degradation of the gaseous formaldehyde was investigaged by indoor and outdoor visible lights. The films were synthesized by Peroxo Titanic Acid (PTA) method. The physicochemical properties of prepared samples were characterized using SEM and UV-vis absorption spectroscopy. It was found that the average film thickness of all coated samples was about 394 ± 5 nm. The band gap energy of un-doped and co-doped photocatalysts was 3.08 and 2.88 eV, respectively. The photocatalytic experimental results showed that the co-doped TiO_2-SiO_2 thin film yield higher photocatalytic efficiency. Under the outdoor light (sunlight in the shade condition) irradiation, with the initial concentrations of formaldehyde of 1000, 3000 and 5000 ppmV, the efficiencies of formaldehyde degradation were 94.7%, 89.5% and 85.1%, respectively. Under the indoor light (the fluorescent lamp) irradiation, with the same formaldehyde initial concentrations, the photocatalytic activities were 87.4%, 85.3% and 81.5%, respectively.