Effect of annealing temperature on the photocatalytic and photoelectrochemical activity of SnOx-TiO2 nanocomposite thin films

Wilfred Thomas, Sadasivan Shaji, David Avellaneda Avellaneda, and Bindu Krishnan

Facultad de ingenieria Mecanica y Electrica (FIME), Universidad Autonoma de Nuevo Leon



Metal oxide-based photocatalysts are highly effective in oxidatively breaking down pollutants. More research is needed in this field for two reasons: the difficulty of removing powder-form photocatalysts after pollutant degradation and the inability to harness solar radiation to its full potential due to the material's wide band gap and high recombination rates of photo-generated excitons. In this study, SnOx-TiO2 heterogeneous nanocomposite photocatalysts were synthesized utilizing SnO and TiO2 precursors. An ingenious binder-free fabrication approach was employed to create a thin film photocatalyst utilizing the Doctor blade technique. The thin films were vacuum annealed at different temperatures to correlate the annealing effect on photocatalytic and photoelectrochemical activities. In contrast to previous findings, X-ray diffraction confirmed the occurrence of anatase TiO2 as a dominant phase at high temperatures. The Raman spectra investigation validated the phase transition and defect induction upon annealing at elevated temperatures. X-ray photoelectron spectroscopy was used to assess the composition and chemical environment of the synthesized thin films. The thin film surface was discovered with porous character using field emission scanning electron microscopy. UV-Vis-NIR spectroscopy results revealed a decrease in bandgap from 3 eV to 2.6 eV, along with increased visible light absorption. The improved oxygen evolution reaction, redox nature, and charge carrier formation were demonstrated utilizing photo-electrochemical techniques. The enhanced visible light-driven cyclic photocatalytic activity of the nanocomposite samples was established by using cationic and anionic model pollutant dyes. These findings demonstrate a simple method for producing defects-induced heterogeneous nanocomposite thin films with increased visible light activity and validating the role of annealing temperature upon making them suitable for visible light applications.



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