Synthesis, characterization, and enhanced photocatalytic performance of a ternary SnO ₂ /TiO ₂ /g-C ₃ N ₄ composite: proposal of a novel activation mechanism under near-UV light

Abstract Nanoparticulate novel ternary photocatalysts comprising SnO 2 , TiO 2 and g-C 3 N 4 was successfully synthesized by the wet impregnation method with ethanol. Ternary SnO 2 /TiO 2 /g-C 3 N 4 was fully characterized by XRD, UV–vis diffuse reflectance spectroscopy, FTIR, TEM and HRTEM. The results confirmed that the photocatalyst was formed with four phases TiO 2 anatase, TiO 2 rutile, tetragonal rutile-type structure of SnO 2 and g-C 3 N 4 . The band gap energy value of prepared SnO 2 /TiO 2 /g-C 3 N 4 was 2.81 eV indicating that this composite can work under both near UV and Visible light. The degradation of ciprofloxacin hydrochloride, a persistent pharmaceutical contaminant of environmental interest, was used as a model to evaluate the photocatalytic efficiency of the synthesized materials. The test of photocatalytic degradation of ciprofloxacin showed a synergistic effect among SnO 2 , TiO 2 and g-C 3 N 4 because 90 % of CIP removal was achieved in 150 min. This performance was faster than pristine and binary materials. The ternary photocatalyst SnO 2 /TiO 2 /g-C 3 N 4 showed the highest value of the apparent reaction rate constant (0.0142 min −1 ). A novel activation mechanism for SnO 2 /TiO 2Anatase /TiO 2Rutile /g-C 3 N 4 under near UV Light was proposed. Comparing the power of the lamps and the reaction volume, this work suggests that the ternary photocatalyst SnO 2 /TiO 2 /g-C 3 N 4 achieved a better performance with respect to what was reported in previous works.