Photocatalytic Degradation of Different VOCs in the Gas-Phase over TiO2 Thin Films Prepared by Ultrasonic Spray Pyrolysis

Abstract

In this study, we deposited TiO2 thin films onto borosilicate glass by ultrasonic spray pyrolysis at 350 and 450 °C. The aim of study is to determine the effect of deposition temperature on photocatalytic activity of TiO2 thin films and to investigate the performance of TiO2 thin films on photocatalytic degradation of methyl tert-butyl ether (MTBE), acetone, acetaldehyde, and heptane as functions of different operating parameters. TiO2 thin films deposited at 350 and 450 °C have a thickness value of 190 and 330 nm, respectively. All as-prepared TiO2 films possess an anatase crystalline structure. According to the X-ray photon spectroscopy (XPS) study, the TiO2 thin film deposited at 350 °C showed a higher amount of oxygen vacancies and hydroxyl groups on the film surface after UV treatment. The aged-TiO2 thin film deposited at 350 °C showed a water contact angle (WCA) value of 0° after 10 min UV irradiation, showing superhydrophilic surface behavior. The TiO2 film deposited at 350 °C exhibited the highest amount of conversion of MTBE (100%). The results also showed that TiO2 films are capable of photocatalytic degradation of MTBE (100%) and acetaldehyde (approx. 80%) in humid air conditions and high airflow rate. The visible-light-activity of TiO2 thin films was tested with 5 ppm MTBE and acetone. TiO2 thin films deposited at 350 °C with a surface area of 600 cm2 showed 60% of MTBE and 33% of acetone degradation under VIS light.

Thickness Effect on Photocatalytic Activity of TiO2 Thin Films Fabricated by Ultrasonic Spray Pyrolysis

“…Recently, we showed that the optimal deposition temperature of TiO 2 films by USP is 350 • C. These TiO 2 films with a material quantity of 0.2 mg/cm 2 effectively degraded volatile organic carbon species such as acetone, acetaldehyde, and heptane [2]. However, despite the many advantages, including the easy scale-up in industry and the possibility to promptly cover large areas, there are a limited number of studies about TiO 2 thin films deposited by the USP method as a photocatalytic material [2,20,24]. To the best of our knowledge, no comprehensive study has been reported focusing on the thickness effect on the photocatalytic activity of USP-prepared TiO 2 thin films.…”

A post-deposition annealing approach for organic residue control in TiO2 and its impact on Sb2Se3/TiO2 device performance

“…A few recent studies from the photocatalysis field have shown the presence of carbon species in USP TiO 2 films after air annealing at temperatures ≥500 °C and after additional ultraviolet treatments. 38…”

“…The XPS results prove that the organic residuals of the USP precursor solution are not easily removed as vapors of H 2 O and CO and CO 2 gas at the stage of the USP deposition at 340 C and during post-deposition air treatment at 450 C. A few recent studies from the photocatalysis eld have shown the presence of carbon species in USP TiO 2 lms aer air annealing at temperatures $500 C and aer additional ultraviolet treatments. 38 Moreover, the carbon was found to be benecial for the photocatalytic performance of TiO 2 . 39 The same TTIP-AcacH based precursor solution is widely used for the spin coating and USP deposition of planar TiO 2 lms as an electron transport layer in perovskite solar cells.…”

Transparent TiO2 thin films with high photocatalytic activity for indoor air purification

“…A similar tendency of a negative water vapour effect on heptane photooxidation due to competitive adsorption on the surface was observed in other studies. 7,40…”