Enhanced visible photocatalytic activity of nitrogen doped single-crystal-like TiO₂ by synergistic treatment with urea and mixed nitrates

N-doped single-crystal-like TiO2is claimed to be a very promising material among various catalytic. In this paper, N-doped single-crystal-like TiO2(N-S-TiO2) samples were firstly prepared by molten salt method with urea and mixed nitrates as synergistic doping agents, therein, the mixed nitrates works also as a morphology modifier to form a single-crystal-like structure in the sample. The nitrogen content in the N-S-TiO2sample could be improved because of the adding of NaNO3and KNO3mixed nitrates compared with using urea as a single nitrogen source. UV–Vis absorption spectroscopy analysis indicated that the nitrogen doped TiO2has a red shift of the light absorption edge. The presence of N–O bonds on the surface of the N-S-TiO2samples could be confirmed by x-ray photoelectron spectroscopy. The degradation efficiency of N-S-TiO2to methylene blue under visible light is the best compared with different TiO2samples without the treatment of mixed nitrates.