Photocatalytic performance of binary and ternary composites based on TiO2 modified with tin and/or carbon in the hydrogen production reaction

Titanium dioxide modified with tin and/or carbon was synthesized by sol-gel method and characterized by X-ray powder diffraction, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller and Barret–Joiner–Halenda methods, Fourier transform infrared and UV-vis diffuse reflection spectroscopies. Modification of TiO2 with tin led to the formation of three-phase samples consisting of anatase (TiO2), rutile (TiO2), and SnO2 with a rutile-type crystal lattice. Simultaneous modification of TiO2 with carbon and tin favored the formation of two-phase samples with anatase and rutile structures. Modification of TiO2 with tin and/or carbon led to increased specific surface area and reduced band gap. The photocatalysts have shown good performance for the photocatalytic production of hydrogen under the irradiation with ultraviolet light using ethanol as the sacrificial agent. The results showed that the TiO2 modified with tin exhibited twice an increase in photocatalytic activity over the pristine TiO2. Among the three-phase samples, the most active one contained 2.29% at. Sn, while among the two-phase samples, the sample 1SnO2/C/TiO2 with atomic percentage of modifier 6.59 (C) and 2.06 (Sn) showed the better activity. The improvement in photocatalytic performance is attributed to the increase in specific surface area, the reduction in the band gap and the presence of heterojunctions between the different phases.