Preparation and properties of La3+ -doped TiO2 nanowires

Nanowires of sodium titanate, TiO2 and La3+/TiO2 were synthesized by hydrothermal method, and their microstructure, optical properties and valence states of exterior elements were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high-resolution electron microscope (HREM), X-ray photoelectron spectroscopy (XPS) and UV-Vis diffuse reflectance spectroscopy techniques. At the same time, the photocatalytic activities of the materials for degradation of methyl orange under visible-light irradiation were also investigated. The results showed the formation of nanowires of sodium titanate with average crystallite sizes of 50-200 nm and in lengths from several microns to several dozens microns, and its chemical formula was determined to be Na2Ti3O7. TiO2 and La3+/TiO2 nanowires were prepared from the Na2Ti3O7 nanowires via ion exchange (i. e., with H+ and La3+ ions) and high temperature sintering processes. These three kinds of nanowires showed different photocatalytic activities for degradation of methyl orange. Na2Ti3O7 nanowire did not show any photocatalytic activity for methyl orange degradation, while TiO2 nanowire was superior to Na2Ti3O7 nanowire; and La3+/ TiO2 nanowire possessed the highest photocatalytic activity.EI0212921-29254