Photocatalytic behavior of titania coatings fabricated by suspension and solution precursor plasma spray processes

Titania (TiO2) powder is the most extensively employed photocatalyst for the purification of water. Nonetheless, the usage of conventional powder catalysts in water treatment has the limitation of settling of the catalyst during the reaction and the additional step of separation of the powders from the liquid. To overcome this limitation and extend the application of TiO2 for practical applications, coatings are promising. In the present study, a comparison of the photocatalytic property of titania coatings deposited by suspension plasma spray (SPS) and solution precursor plasma spray (SPPS) methods using similar plasma spray parameters is presented. The coatings are characterized by field emission scanning electron microscopy, profilometry, X-ray diffractometry, and Raman spectroscopy. The photocatalytic performance and efficiency of photodecomposition of the developed coatings are studied using methylene blue as the organic pollutant. The study demonstrates a higher photocatalytic activity and photodecomposition efficiency for the SPPS titania coating compared to SPS titania coatings. The improved performance is attributed to the presence of oxygen vacancies and is corroborated with X-ray photoelectron spectroscopy. The SPPS titania coatings hold promise for industrial-scale applications as it is economical, simple and does not involve multiple steps.