One-pot synthesis and improved photocatalytic performance of Sn/Cl co-doped TiO2-ZnO nano-heterojunctions

Pure TiO₂, Sn/Cl co-doped TiO2 and Sn/Cl co-doped TiO₂-ZnO were fabricated and compared by a novel one-pot method to improve the photocatalytic performance of pure TiO2, which accomplishes the construction of heterojunctions simultaneously with doping by volatile solid solution. TG-DSC, XRD, FTIR, XPS, SEM, EDS, TEM, SAED, UV–Vis, PL and EIS were characterized to investigate the influence mechanism of Sn/Cl co-doping and ZnO content (0, 25, 50, 75, and 100 mol.%) on the thermal effect, crystal structure, morphology, composition, charge transfer behavior and photocatalytic performance of samples. Results indicate that ZnO appears and SnO2 disappears simultaneously with anatase TiO2 as the main phase by increasing ZnO content, and the morphology is changed from irregular sphere to sphere-sheet and sphere-plate correspondingly. The photocatalytic degradation efficiency first increases and then decreases, and achieves the maximum value of 73 % by SCT/Z50 which has sphere-sheet heterostructure containing more hydroxyl radicals, under 15 W weak-UV light irradiations for 3 h using methyl orange (MO) as pollutant. The excellent photocatalytic performance is attributed to the structural and morphological effects of Sn/Cl co-doping and ZnO introduction, which can increase the electron-hole separation efficiency. The optimized composition also has great potential in practical photocatalytic application due to the commercial advantage that ZnO is much cheaper than TiO2.