Enhancement of photocatalytic activity on salicylic acid by nonmetal-doped TiO₂ with solvothermal method

Nonmetal-doped TiO₂ nanoparticles have been prepared by the solvothermal method. The as-prepared photocatalysts have been characterized by X-ray diffraction, UV–vis diffuse reflectance spectra, Scanning electron microscope, Transmission electron microscopy, Specific surface area (BET) and X-ray photoelectron spectroscopy. The results indicate different atom radius and valence of the N, S and B atoms that cause the different doping ways, and it could form different lattice, which led to different surface area and pore volume of as-prepared photocatalysts. It is confirmed that S as S⁶⁺ incorporate into the crystal lattice of the S–TiO₂, which may be the O–S–O–Ti–O linkages in the crystal lattice. It may be N and S as Ti–N–O or Ti–N–O₂ and S²⁻ in the crystal lattice of the N&S co-doped TiO₂, respectively, which may be the S–Ti–N–O linkages in the crystal lattice. Photocatalytic activity was studied by degradation of salicylic acid under visible light. The degradation rate of salicylic acid reached 76.25% with N&S co-doped TiO₂ photocatalyst in 120 min, which is the highest of all the as-prepared photocatalysts. Furthermore, the experimental data of photocatalytic degradation well followed the Langmuir–Hinshelwood kinetics.