Application of a piezo-photocatalytic thin film (FTO/BaTiO3/SnO2) for enhanced degradation of organic pollutants and disinfection of wastewater

In recent years, the removal of organic pollutants (dyes and pharmaceuticals) and microbes from polluted water has remained a significant concern. We report a novel biosynthesized SnO2 loaded fluorine-doped tin oxide/barium titanate (FTO/BTO) thin film for piezo-photocatalytic degradation of methyl orange (MO), methylene blue (MB) and ciprofloxacin (CIP), as well as for the removal of gram-negative E. coli and gram-positive S. aureus bacteria from water. Piezo-photocatalyst thin films were characterised using XRD, FTIR, FE-SEM, TEM, TGA, BET, XPS, PL and UV-DRS spectroscopy. The deposition of the small spherically shaped SnO2 nanoparticles on the surface of BaTiO3 was confirmed by TEM, EDS and FTIR. Chronoamperometry and electrochemical impedance spectroscopy (EIS) were employed to determine piezo-electrochemical properties of the prepared piezo-photocatalyst thin films. The results showed that BaTiO3 loaded with SnO2 on its surface, exhibited a higher piezo-electrochemical current than pure BaTiO3 (BTO). FTO/BaTiO3@0.2%SnO2 generated about 1.3 mA current under ultrasonic vibration, which is more than 6 times that of pure FTO/BaTiO3. Furthermore, FTO/BaTiO3@0.2%SnO2 showed a better degradation efficiency of 94, 92 and 64% for MO, MB and CIP, respectively. Additionally, BaTiO3@0.2%SnO2 was shown to have a higher antibacterial activity against gram-negative E. coli bacteria than against gram-positive S. aureus bacteria. Overall, this study showed that the piezo-photocatalytic activity of BaTiO3 could be improved through SnO2 loading. Moreover we were able to demonstrate that BaTiO3/SnO2 composites may be employed as multifunctional catalysts based on their ability to break down various organic contaminates (dyes and pharmaceutical pollutants), and to remove bacteria from wastewater.