Photocatalytic Activity of Toluene under UV-LED Light with TiO2 Thin Films

Titanium dioxide (TiO2) and ferric-doped TiO2 (Fe-TiO2) thin films were synthesized on the surface of 304 stainless steel sheets using a simplified sol-gel preparation method. The Fe-TiO2 thin films were prepared with weight-to-volume ratios of Fe3+/TiO2 of 0.3%, 0.5%, and 0.7%, respectively. The crystalline phase structures of the prepared TiO2 and Fe-TiO2 thin films were entirely anatase. The measured optical band gaps of the TiO2, 0.3% Fe-TiO2, 0.5% Fe-TiO2, and 0.7% Fe-TiO2 thin films were 3.27, 3.28, 3.22, and 2.82 eV, respectively. The grain sizes and other physical properties of the prepared thin films were also reported. The kinetics of the photocatalytic processes under a UV-LED light source could be explained by the Langmuir-Hinshelwood kinetic model with the specific rates of 2.00 x 10(-3), 4.00 x 10(-3), 5.00 x 10(-3), and 7.00 x 10(-3) min(-1)mW(-1), for TiO2, 0.3% Fe-TiO2, 0.5% Fe-TiO2, and 0.7% Fe-TiO2, respectively. An increase in Fe3+ dopant concentration could enhance the photocatalytic activity of toluene decomposition as a result of lower optical band gaps, smaller grain size, and higher surface area.