Novel method for preparation of high visible active N-doped TiO₂ photocatalyst with its grinding in solvent

This work is focused on improvement on the photo-catalytic activity of a N-doped TiO₂ (reference sample) by its grinding in solvent. Grinding the reference sample in solvent was performed by using a planetary mill at 200 rpm and 15 min grinding time with one of various solvents such as ethanol, ethyl acetate dehydrated (EAD), hexane and water. The ground samples were dried at 80 °C to remove the residual solvents. The prepared sample was characterized by a series of analytical methods including X-ray diffraction (XRD), specific surface area (SSA), particle size, Fourier transform infrared spectroscopy (FT-IR), thermogravimeter mass spectrometer (TG-MS), X-ray photoelectron spectroscopy (XPS), Chemiluminescence as well as the photo-catalytic activity with NO gas decomposition. The prepared sample ground in ethanol showed much improved photocatalytic activity in the wavelength of visible light region, in comparison with the activity of the reference sample. This may be due to the existence of abundant electrons on Ti³⁺/oxygen vacancy sites, which may be generated via current-doubling effect during the dry operation. On the contrary, the sample prepared in EAD showed the worsened photocatalytic activity in visible wavelength region, due to the existence of acetate complex on the surface of the sample as a surface impurity.