| Development of photocatalytic oxidation technology offers a new path to solve the environment pollution and energy shortage problems. The focus is to expbit appropriate photocatalyst. There are some methods to improve the performance of photocatalytic oxidation, such as increasing the surface area, adjusting band gap, exposing suitable crystal face. Nanotube, which is an preeminent photocatalyst nanomaterial, has been widely studied due to many excellent performance and great potential for development. Layered niobate K4Nb6O17, both its precursor materials and modified materials, own good prospects in optical, electrical and other fields. Niobate nanotubes, a good support for preparing composite materials, can be prepared in relatively simple moderate conditions, and it has also been greatly developed.In my dissertation, K4Nb6O17 was prepared by a high temperature solid state reaction method, then modified by proton-exchange, exfoliation, acid precipitate, sol-sol composite method, etc. The properties of mateiails were characterized by XRD, FESEM, HRTEM, N2adsorption-desorption, Raman, H2-TPR. MB was employed as probe molecule to evaluate the photocatalytic performance under visible light. The results are described as follows:Nanotubes NT-H4Nb6O17, formed by scrolling laminate itself, own specific surface area of 64 m2·g-1, pore volume of 0.32 cm3·g-1, tube diameter of ca.13～24 nm and tube length of 290～500 nm The terminal Nb-O bonds are susceptible to the surrounding environment, and Nb-OH bonds are formed after proton-exchange and exfoliation. The band gap of nanotube NT-H4Nb6O17 are broaden due to the quantum size. The photocatalytic performance of nanotube NT-H4Nb6O17n is not excellent. However, the absorption capability of visible light is stronger than K4Nb6O17 and H4Nb6O17.composites own nanotube structure, and the oxide nanoparticles are dispersed in the inner and outer surfaces of the nanotubes. It own specific surface area of 114 m2·g-+1, pore volume of 0.41 cm3·g-1. The nanotube diameter are slightly decreased compared to NT-H4Nb6O17. The absorption capability of visible light over Fe2O3@Nb6O17 composites is enhanced and exhibit well photocatalytic performance. After compositing oxide sol with niobate support, the niobate support are spontaneously scrolled to the nanotube structure. The Nb-OH bonds in support are used as the reaction active sites to link support and oxide nanoparticles, the composites own stronger interaction between oxide and nanotube.TiO2@Nb6O17 composites own curved nanoscroll structure, the 1102 nanoparticles are highly dispersed on the surface of nanoscrolls in the form of polyhedron species of Ti oxides, and the formations of niobate nanotube composites are affected by the crystallinity of guest sols. TiO2@Nb6O17 composites own specific surface area of 190 m2·g-1,pore volume of 0.41 cm3·g-1,pore size distribution of 4-10 nm due to the scattered stack of nanosheets. It has a better ability to absorb visible light It exhibits preeminent photocatalytic activity. Due to the strong interactions, a strong chemical bonds are formed, maybe the Nb-O-Ti bonds. Conbined with the quantum size effect of TiO2 nanoparticles, the valence band of composite may be adjusted. Therefore, the composites own strong absorption capability of visible light, and excellent photocatalytic performance. |
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