Fabrication of binary SnO2/TiO2 nanocomposites under a sonication-assisted approach: Tuning of band-gap and water depollution applications under visible light irradiation

Antibiotics and organic dyes are both significant causes of water pollution, and their removal from, or degradation in, water systems can be difficult. To address this issue, SnO2-modified TiO2 nanocomposites (STOs) were fabricated using a sonication-impregnation method. The prepared STOs (STO-1, STO-2, and STO-3) were characterized through various techniques including powder X-ray diffraction, Fourier-transform infrared spectroscopy, UV?vis diffuse reflectance spectroscopy, photoluminescence, high resolution-transmission electron microscopy, and X-ray photoelectron spectroscopy. The fabricated STOs exhibited narrowing of their bandgap and enhanced absorption in the UV and visible region. The STOs were further tested for their use in the photocatalytic degradation of tetracycline hydrochloride (TC) under visible light irradiation and were found to be very suitable for this application. The adsorption of TC on the STOs reached nearly 56%?62% after 15 min in the dark, while the vast majority degraded (81%?95%) within 20 min of visible light exposure. The narrowed bandgap and surface-based properties played a significant role in improving the adsorption-degradation efficiency of TC by extending the absorption spectrum and enhancing the separation efficiency of charge carriers. Moreover, the degradation of MB and CR was performed using STO-1 and displayed over 97% and 90% degradation, respectively. Thus, an effective method to utilize a non-noble photocatalyst to efficiently degrade antibiotics and organic dyes was achieved.