模板法制备的Fe~(3+)/TiO_2中空纳米纤维的光催化性能

摘要

Fe~(3+)-doped TiO_2(Fe~(3+)/TiO_2) hollow nano-fiber photocatalytic material was prepared via two steps method of soaking and thermal transition using the cotton fiber as the template, and characterized by SEM, XRD, UV-Vis and techniquies. The effect of the calcination temperature and time on the photocatalytic activity of the Fe~(3+)/TiO_2 nanofiber material was investigated using the degradation of methylene blue(MB) solution as the model reaction. The results show that the catalytic acitivity of the Fe~(3+)/TiO_2 hollow nano-fiber is higher than that of TiO_2 with the same mophology under solar light. The catalytic activity is related to the size and phase structure of the material but also to the superficial charge property. The higher the charge, the more the surface structural defect and the more the surface active sites are, the higher the catalytic activity is. The highest negative charge and the best catalytic activity are found for the Fe~(3+)/TiO_2 material calcined at 500 ℃ for 2 h with anatase structure of TiO_2 due to a large number of nanosized particles on the surface. For example under solar light, the decolorizing efficiency of MB solution reaches 93% in 2 h on Fe~(3+)/TiO_2 nanofiber material and 100% in 6 h while the efficiency is about 70% on the pure TiO_2 nanofiber material. This material also shows good catalytic stability and is easily removed from the system after reaction: the decolorizing efficiency of MB solution remains above 90% after 5 cycles.%以棉花纤维为模板,利用浸渍-热转化两步法制备了Fe~(3+)掺杂的二氧化钛(Fe~(3+)/TiO_2)中空纳米纤维光催化材料,并利用扫描电镜(SEM)、X射线衍射(XRD)、紫外-可见光谱(UV-Vis)和ζ电位等技术对其形貌、结构、光吸收特性及其表面状态等进行了表征.以亚甲基蓝(methylene blue,MB)溶液的脱色降解为模型反应,考察了煅烧温度与时间对Fe~(3+)/TiO_2中空纳米纤维光催化性能的影响.结果表明:利用该法可以制得棉花纤维形貌的Fe~(3+)/TiO_2中空纳米结构材料;所得材料的催化性能除与材料的尺寸、相结构有关外,还与表面荷电性质有关,表面荷电量越高、表面结构缺陷越多、表面活性位越多,催化活性越高.500℃下煅烧2 h所得材料表面长有大量的粒子(平均尺寸为12 nm),其中TiO_2为锐钛矿结构,表面荷负电荷量最高,催化性能最好,如在太阳光下,2 h可使MB溶液的脱色降解率达93%,6 h完全脱色,而在纯TiO_2中空纤维材料上约为70%;该材料还具有良好的催化稳定性能,重复使用5次仍可使MB溶液的脱色降解率保持在90%以上,且该催化剂材料易于离心分离去除.