Investigating the structural, optical, and photocatalytic activity of TiO <sub>2</sub> /SnO <sub>2</sub> nanocomposites synthesized by the facile sol-gel technique for dye degradation
F. Soleimani, Mohammad Bagher Rahmani
Abstract
Abstract The photocatalytic degradation of dyes using semiconducting metal oxides has received a lot of interest recently. In this work, TiO 2 , SnO 2 , and TiO 2 /SnO 2 nanocomposites with different SnO 2 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 SnO 2 content. Raman spectroscopy confirmed the XRD results. Electron microscope images revealed that the TiO 2 /SnO 2 composites have composed of semi-spherical fused particles, where increasing the SnO 2 content causes the reduction of the particles’ size. The addition of SnO 2 caused the photoluminescence (PL) intensity reduction due to the easy migration of photoelectrons from the TiO 2 to the SnO 2 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 TiO 2 showed better photocatalytic activity than pure SnO 2 , but the color degradation was still less than 50% after 90 min. UV irradiation. Increasing the SnO 2 content in the TiO 2 produced nanocomposites with higher color degradation rates of about 73% after 90 min. UV irradiation, suggesting the binary metal oxide TiO 2 /SnO 2 nanocomposite photocatalyst as a promising candidate for effluent dye removal.