Analysis of sol aging effects on self-cleaning properties of TiO₂thin film

This study investigated the effect of aging TiO2 Sol on the final thin film performance using the heat-assisted sol-gel synthesis method. The sol was aged 24 h, 48 h, and 72 h respectively before being spin-coated on glass substrates. The annealing of the coated thin films occurred at 600 C. The scanning electron microscope, x-ray diffraction (XRD), and UV-vis spectrophotometer characterized the thin films to ascertain morphological, structural, and optical properties. Also, methylene blue degradation characterized the thin films to confirm the self-cleaning properties. The result revealed that aging time influences the ability of the electrons to gather or transit. The light absorption experienced an increasing shift in value. Also, light absorption optimized with absorption bands with peak intensities becoming strong as aging time increased. Aging the TiO2 Sol caused micro and macro-structural transformations. The structural analysis showed anatase with possible transitioning to rutile as aging time increased. Crystallite size from the most prominent peak range from 3.61 nm to 21.77 nm as aging time increased from 24 h to 72 h and 19.31 nm for rutile at 72 h. The optical bandgap dropped from 3.51 eV to 3.26 eV as aging time increased from 24 h to 72 h. The morphology showed increasingly uniformly distributed shapes of TiO2 particles scattered over the surface of the substrate as aging time increased. The self-cleaning test showed the thin film has a high degradation efficiency of methylene blue dye in the range of 72.50 to 92.90% confirming substantial, self-cleaning property.