稀土La^3＋掺杂TiO2纳米线的制备及其性能研究

摘要

. Nanowires of sodium titanate, TiO2 and La^3+/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 visibleqight irradiation were also investigated. The results showed the formation of nanowires of sodium titanate with average crystallite sizes of 50-200nm and in lengths from several microns to several dozens microns, and its chemical formula was determined to be Na2Ti3OT. TiO2 and La^3+/ TiO2 nanowires were prepared from the Na2Ti3O7 nanowires via ion exchange (i. e. , with H^+ and La^3+ ions) and high temperature sintering processes. These three kinds of nanowires showed different photocatalytic activities for degradation of methyl orange. Na2Ti3 07 nanowire did not show any photocatalytic activity for methyl orange degradation, while TiO2 nanowire was superior to Na2Ti3O7 nanowire; and La^3+/ TiO2 nanowire possessed the highest photocatalytic activity.%采用水热法制备了钛酸钠纳米线、TiO2纳米线和La^3＋／TiO2纳米线。利用XRD、SEM、HREM、XPS和UV—Vis等技术手段对样品微观结构、光学性能和表面元素价态进行了分析；并以甲基橙溶液为目标污染物测试其光催化性能。研究表明，实验合成了直径为50～200nm、长度为十几微米到几十微米的钛酸钠纳米线，并通过对微观结构的分析，初步确定其分子式为Na2Ti3O7，钛酸钠纳米线经过氢离子和镧离子进行离子交换并高温烧结得到了TiO2纳米线和La^3＋／TiO2纳米线；钛酸钠纳米线对甲基橙溶液几乎没有光催化降解作用，而TiO2纳米线具有较高的光催化活性，其中样品La^3＋／TiO2纳米线光催化性能最强。