Investigating the structural, optical, and photocatalytic activity of TiO2/SnO2 nanocomposites synthesized by the facile sol-gel technique for dye degradation

Abstract

The photocatalytic degradation of dyes using semiconducting metal oxides has received a lot of interest recently. In this work, TiO2, SnO2, and TiO2/SnO2 nanocomposites with different SnO2 contents were synthesized via the facile and cost-effective sol-gel method and fully characterized. X-ray diffraction (XRD) pattern analysis indicated that the crystallite size reduced remarkably and the transformation of anatase to rutile phase accelerated significantly with increasing the SnO2 content. Raman spectroscopy confirmed the XRD results. Electron microscope images revealed that the TiO2/SnO2 composites have composed of semi-spherical fused particles, where increasing the SnO2 content causes the reduction of the particles’ size. The addition of SnO2 caused the photoluminescence (PL) intensity reduction due to the easy migration of photoelectrons from the TiO2 to the SnO2 conduction band, leading to a decrease in the recombination of photogenerated electron-hole pairs. Catalytic activity was tested by methylene blue under 360 nm ultraviolet (UV) irradiation. Intrinsic TiO2 showed better photocatalytic activity than pure SnO2, but the color degradation was still less than 50% after 90 min. UV irradiation. Increasing the SnO2 content in the TiO2 produced nanocomposites with higher color degradation rates of about 73% after 90 min. UV irradiation, suggesting the binary metal oxide TiO2/SnO2 nanocomposite photocatalyst as a promising candidate for effluent dye removal.