<span style="font-size:11.0pt;mso-bidi-font-size: 10.0pt;font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-GB;mso-fareast-language:EN-US;mso-bidi-language:AR-SA" lang="EN-GB">Photocatalytic decomposition of acetaldehyde gas on TiO₂-SiO₂ thin film photocatalyst ― A kinetic analysis</span>

Abstract

TiO₂-SiO₂ thin film photocatalysts with 5 (TF95/5) and 10 w/w% (TF90/10) SiO₂ contents have been prepared via sol-gel method. Characterization using X-ray diffractormeter and field emission scanning electron microscopy is performed to investigate the effect of SiO₂ doping on the TiO₂ thin film’s physico-chemical properties. The photocatalytic performance of the thin films is evaluated using the degradation of acetaldehyde gas at various initial concentrations under fixed intensity UV irradiation. A Langmuir-Hinshelwood kinetic model is used to analyze the kinetics of the photocatalytic reaction. It is found that the first order reaction rate constant (<i style="mso-bidi-font-style: normal">k</i>) of the TF95/5 thin film photocatalyst (1.2438 µmol dm^-3 min^-1) is higher than that of TF90/10 thin film (0.3648 µmol dm^-3 min^-1). This is attributed to higher crystallinity of the TF95/5 thin film, resulting in more active charge carrier generation. However, TF90/10 thin film photocatalyst with smaller TiO₂ particles shows four times stronger adsorbability of acetaldehyde than TF95/5 due to its higher surface area.