Formation of Nano-particle Titanic Fibers with High Photocatalytic Activity

TiO_2光催化剂的应用领域日益广泛，尤其是在环境保护方面。因此，对其形貌和光催化活性的优化是其应用的关键。如果可以获得纤维状钛，则由于其易于处理和低压力损失，广泛的应用被认为是可能的。本论文研究了纤维状TiO_2的合成与表征，通过在78 ~ 100℃下干燥单分散TiO_2颗粒的悬浮液，制备了宽度为50 ~ 250 μm、长度为几~ 10 cm的均匀纤维状TiO_2。纤维宽度随悬浮液浓度、颗粒直径的增加或干燥温度的降低而增加。研究了热处理对纤维结晶度、晶型、斑点表面积和孔径的影响。经400℃热处理的TiO_2纤维具有180m^2/g的高比表面积，同时具有由颗粒内孔形成的中孔（0.57nm）和由颗粒间孔形成的均匀中孔（30 nm）。由TiO_2溶胶（D= 7 nm）制备的TiO_2纤维，经400 ~ 800℃热处理后，其光催化活性提高，NOx分解率达98%。采用TiO_2溶胶（D= 6 nm）和SiO_2溶胶（D=8 × 11nm）制备了TiO_2-SiO_2纤维。SiO_2的加入提高了TiO_2的光催化活性，SiO_2含量为0wt%，40wt%，NOx分解率为93%，SiO_2含量为0wt%，SiO_2含量为40wt%，SiO_2含量为0wt%，SiO_2含量为0wt%，SiO

Various applications, especially those for environmental, are developing for TiO_2 photocatalyst. For its application, optimization of the morphology and photocatalytic activity are the important. If it is possible to obtain a fibrous titanic, a wide range of applications are considered to be possible, because of its easiness in handling and low pressure loss. In this study, the synthesis and characterization of fibrous TiO_2 was investigated.Homogeneous fibrous TiO_2 with 50 to 250 μm of width and a few to 10cm of length was prepared by drying the suspension of the monodispersed TiO_2 particles at 78〜100℃. The fiber width increased with increasing concentration of suspension, particle diameter, or with decreasing drying temperature. The fibers had a rectangular plate-like shape and TiO_2 particles were densely and homogeneously packed to form the fibers.The effects of a heat treatment on crystallinity, crystal type, speck surface area and pore size of the fibers were investigated. The TiO_2 fiber heat-treated at 400℃ had a high specific surface area as 180m^2/g and had both of micropore (0.57nm) caused by infra-particle pore and homogeneous mesopore (30nm) caused by inter-particle pore. The crystal type maintains anatase after heating even at 1000℃ depending on preparation conditions.The photocatalytic activity of the titanic fibers formed from TiO_2 sol (D=7nm) increased by heat-treatments between 400〜800℃ and showed such a very high activity as 98% of NOx decomposition. The crystallinity also affects the photocatalytic activity.The TiO_2-SiO_2 fibers were developed by using TiO_2 sol (D=6nm) and SiO_2 sol (D=8〜11nm). The photocatalytic activity of titanic increased by the addition of SiO_2 with the adsorptive action, i.e., 76% of NOx decomposition for 0wt% of SiO_2 content fibers and 93% of NOx decomposition for 40wt% of SiO_2 content fibers, and the strength of TiO_2 fibers were also increased by feat-treatments and the addition of SiO_2.