摘要
二十世纪以来，人类的工业文明得以迅速发展，由此引发的能源危机和环境污染成为人们亟待解决的问题。占地球总能量的99％以上的太阳能作为一种可再生资源，具有所有其它能源所不可比拟的优点。因此开发和利用太阳能是解决世界范围内能源危机和环境污染问题的一条重要途径。而纳米光催化技术无论在利用太阳能方面还是在综合治理环境污染方面都展现出了广阔的应用前景。而实现这一技术的关键是高效光催化剂的获得。
氧化物半导体TiO_2是使用最多的光催化剂，但由于其较宽的禁带宽度(3.2eV)限制了其光催化效率的提高。而其他单一的半导体材料又具有各种各样的缺点，因而近年来复合薄膜和颗粒的研究及使用越来越受到广泛的重视。其中层状纳米复合半导体材料由于具有二维空间结构所带来的光催化效率高、反应活性高、反应速度快等特点而成为近期人们研究重点。层状化合物中的铌酸钾K_4Nb_6O_(17)已被证实是一种性能优异的半导体材料，具有光催化和光电转换性能，其独特的结构是处于层间的带正电的K~+可以被其它阳离子所替代，正是由于其多元素、复合型的特点，为材料的修饰和改性提供了广阔的技术空间。
本课题的主要内容是：高温固相反应合成具有层状结构的K_4Nb_6O_(17)晶体材料，然后以此为母体材料，通过离子交换、层间胺插入、硫化处理等过程制备出CdS/H_4Nb_6O_(17)粉末形式的光催化材料；通过旋转涂覆法在石英玻璃基片上制备了K_4Nb_6O_(17)薄膜，采用一定的热处理制度后对薄膜分别进行离子交换、层间胺插入、硫化处理等处理过程制备了CdS/H_4Nb_6O_(17)薄膜形式的光催化材料。最后，在0.1mol／1的Na_2SO_3作为正孔捕捉剂的情况下，用光解水制氢测试装置分别对K_4Nb_6O_(17)粉末、CdS／H_4Nb_6O_(17)粉末、K_4Nb_6O_(17)薄膜、CdS／H_4Nb_6O_(17)薄膜进行了光解水制氢的实验，测得了不同情况下的氢气产生情况。通过XRD检测了粉末和薄膜及其各中间产物的结构，用BET比表面分析仪比较了K_4Nb_6O_(17)粉末与CdS／H_4Nb_6O_(17)粉末的比表面积，采用UV-VIS紫外可见分光光度计分析和讨论了所制CdS／H_4Nb_6O_(17)粉末与CdS／H_4Nb_6O_(17)薄膜材料的光催化活性。最后研究结果表明：(1)固相烧成
武汉理工大学硕士学位论文
反应及条件为:3肠20，+2尤Zc仇一犬4Nb6o:7+ZcoZt(1 Z000c往sm认);(2)
CdS/H必化6017粉末具有比瑜卜七601:粉末更大的比表面积;(3)CdS/H必化6017
粉末与CdS汪么Nb6017薄膜的光吸收闭值分别为2.21eV、2.17eV;(4)
瑜Nb60i7粉末、CdS汪么Nb6O17粉末、K妇b601:薄膜、CdS/场到七6017薄膜的
产氢率分别为:2·15、2.43、0.633、1.15 mmolg一‘h一1。
Since the beginning of the 20th century, energy crisis and environmental pollution caused by the quick development industry civilization have been important problems that people must resolve them right away. The solar energy which covers more than 99% of the total energy in globe is used as a kind of reproducible resource, and it has many advantages that all other energies can't comparing to. Therefore to develop and make use of the solar energy is an important method to resolve the problem of world energy crisis and environment pollution. Nano-photocatalysis technique opens a vast and applicable foreground which no matter what in the aspect of making use of the solar energy and in managing the environment pollution synthetically. However the key to realize the technique is the acquirement of high efficient photocatalyst. Oxide semiconductor TiO2 is the common catalyst, but the wide band gap (3.2eV) limits its improvement of photocatalytic properties. And other single semiconductor's disadvantages also restr
ain their applications in the photocatalytic realm. So the study and use of compound powders and thin films get more and more regards. Among them the double layered structure nanocompound semiconductor become the focus of study by their high photocatalytic efficiency, fast reaction speed etc. It has been confirmed that the potassium niobate (K4Nb6O17) is an excellent semiconductor photocatalyst. Its special construction consists in the ion K+ in the interlayer can be replaced by other cations, which providing vast space of modifying the material.
The tasks of this thesis are following. To synthesize potassium niobate K4Nb6O17 through the high temperature solid reaction. To make CdS/K4Nb6O17 powder on the base of the K4Nb6O17 powder which by the courses of ion exchanging, amine intercalation, sulfuration etc. To obtain CdS/K4Nb6O17 thin film through the same course of making CdS/K4Nb6O17 powder on the base of
K4Nb3O17 thin film on the quartz which made by the spin coating and after heat treatment. To make experiments with additives (Na2SO3, 0.1mol/l) of photocatalytically decomposing water into H2 and O2 to evaluate the photocatalytic activities of the catalyst KNb6O17 powder, CdS/K4Nb6O17 powder, K4Nb6O17 film, CdS/K4Nb6O17 film. The crystalline structures of the midst powder and film productions were investigated by using the X-Ray Diffraction(XRD). The compared surface area of the K4Nb6O17 powder and CdS/KtNbeOn powder were compared by the BET apparatus. The absorption threshold of CdS/K4Nb6O17 powder and film were measured by the UV-VIS spectrophotometer. At last it can elicit the following conclusions, (1) The solid reaction and the reaction condition are,
(2) The compared surface area of the CdS/K4Nb6O17 powder is bigger than powder; (3) The absorption threshold of CdS/K4Nb6O17 powder and were 2.21eV, 2.17eV respectively; (4) The ratio of hydrogen production of photocatalyst K4Nb6O17 powder, CdS/H4Nb6O17 powder, K4Nb6O17film, CdS/H4Nb6O17 film correspond 2.15, 2.43, 0.633, 1.15mmol.g-1.h-1 respectively.
引文
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