Low Temperature Calcination of TiO2 and ZnO Particle Film and Evaluation of Their Photocatalytic Activity

Abstract

<p>In this study, TiO<sub>2</sub>, ZnO, and TiO<sub>2</sub>/ZnO films were prepared under low calcination temperature and characterized to observe their properties related to photocatalytic performance. The samples were prepared by mixing the gel phase of ZnO precursor, TiO<sub>2</sub> anatase powder, triton-x 100, and acetylacetone to produce a paste form for the deposition process. The resulting paste was then deposited by screen printing onto a glass substrate and subjected to calcination at 250C to facilitate the ZnO crystallization and remove other additive materials. XRD analysis confirms that the formation of ZnO and TiO<sub>2</sub> crystals was assisted, although their crystallinity was lower than corresponding particulate forms. The lower crystallinity seems to be related by additive materials remains. The surface morphology of each sample was observed by scanning electron microscopy (SEM) imaging, Brunauer–Emmett–Teller (BET), and contact angle examination. Interestingly, both TiO<sub>2</sub> and ZnO layers tend to have a hydrophobic surface meanwhile TiO<sub>2</sub>/ZnO has a hydrophilic surface. BET analysis revealed that ZnO has the highest specific surface area due to a nanosized. FTIR spectra confirmed the presence of appropriate chemical bonds in the ZnO and TiO<sub>2</sub> and other additive materials, such as alkyl groups. The photoluminescence (PL) spectrum shows a blue emission associated with intrinsic defects such as vacancies and interstitials of Zn and Ti in all samples. Differences in the photocatalytic performance of film and particulate form for each material were observed and analyzed. All samples' structures, morphology, and PL characteristics were then correlated to their photocatalyst behavior for methylene blue degradation.</p>