Microstructure of nitrogen and sulfur co-doped mesoporous TiO₂ film and its photocatalytic activity

Using Ti(OBuⁿ)₄ as the inorganic precursor, Pluronic F127 as the templating agent, and thiourea as the additive, mesoporous anatase TiO₂ thin films were prepared through sol-gel method coupled with evaporation-induced self-assembly (EISA) process. Scanning electron microscope, X-ray photoelectron spectra, N₂ adsorption-desorption, X-ray diffraction, and UV-Vis spectra were used to characterize the as-synthesized mesoporous TiO₂ materials. It is found that, apart from doping N, S elements into the TiO₂ lattice, the mesostructure of the TiO₂ thin films is changed by adding thiourea into the reactive solution. When the mole ratio of thiourea to Ti(OBuⁿ)₄ is 2.5%, the pore size of the synthesized mesostructured TiO₂ reaches 12.4 nm, and the mesoporous TiO₂ sample shows the best UV photocatalytic activity in the degradation of the methyl organge (MO). When the mole ratio of thiourea to Ti(OBuⁿ)₄ is 5%, the absorption edge of the as-synthesized sample can be extended from 380 nm to 520 nm, and the sample exhibits the best visible photo catalytic activity in decomposing the Rhodamine B (RhB).