以光富集为导向的多级蛋壳结构高效TiO2光催化剂的创制

It remains a difficult problem in photocatalysis to develop practical and efficient photocatalysts used in photodecomposition of environmental pollutants. Recent work showed that TiO2 semiconductors with hollow structure have been recognized as a most promising photocatalyst, owing to the capability of increasing light absorption and photocatalytic activity. Whereas, TiO2 with hollow structure still remains much defects, such as, low exposed percentage of active facets, low quantum efficiency , ineffective usage of visible lights. This project was to prepare conductive polymer modified hierarchical TiO2 photocatalysts with exposed reactive facets and yolk-shell structure for the degradation of organic pollutants, which would increase the light absorption, widen the spectral response and raise quantum efficiency. Simultaneously, we will work on the photocatalytic activity and mechanism on the degradation of benzene, formaldehyde and other harmful organic compounds. We will study the photocatalytic mechanism about the separation and transfer of charge carriers as well as the distribution of reactive species under visible light excitation. Also, we will investigate the influence of the composition and structure of conductive polymer on the adsorption and transfer of the pollutants. Moreover, the synergistic effect and the relationship will be discussed among 3D yolk-shell hierarchical structure, the (001) facet and the conductive polymer. Consequently, we have established a controllable method to research the structure and activity relationship between Micro-and macro-structure of the photocatalyst with the light absorption and the photocatalytic performance. Hence, this work will provide us with systemic data and experimental evidence to design and develop photocatalysts with high performance.

开发高效实用的光催化剂应用于环境污染物降解，是当前国际光催化领域的难点问题。基于前期有关具有空腔结构TiO2 光催化剂有利于增加光吸收和光催化活性的研究成果，针对现有空腔结构TiO2 光催化剂活性面暴露率低、量子效率低及不能有效利用可见光等关键科学问题，本项目拟通过多级结构、导电高分子修饰和活性面暴露的设计达到提高材料光吸收、增加光谱响应频率和提高量子效率的目的，制备出多级蛋壳结构高效TiO2光催化剂，考察催化剂在苯系物、甲醛等有毒有机污染物处理中的催化机制和作用效果。研究所制备光催化剂在可见光激发下的载流子分离、转移及活性物种分布等光催化的微观机制；研究导电高分子层组成和结构对反应污染物吸附转移的影响；研究三维蛋壳多级结构、(001)暴露面及导电高分子层的协同作用及对光催化活性的影响本质，建立催化剂微观和宏观结构形貌与光吸收及光催化性能之间的构效关系和控制方法。

开发高效实用的光催化剂应用于环境污染物降解，是当前国际光催化领域的难点问题。针对现有TiO2 光催化剂活性面暴露率低、量子效率低及不能有效利用可见光等关键科学问题，本项目通过构建多级结构、引入异质结和控制活性面暴露，达到提高材料光吸收、增加光谱响应频率和提高量子效率的目的。制备出的多级蛋壳结构高效TiO2光催化剂及其复合材料，具有明显的光富集效果，可增强主客体材料对光的利用率，并可通过光催化作用实现对苯系物、醛等有毒有机污染物的降解，具有一定的应用价值。.项目围绕多级蛋壳结构光催化复合材料的制备、结构调控、光吸收、光催化作用机理及污染物消除方式开展了系列工作。(1) 利用多元醇醇热自组装技术制备多级蛋壳结构TiO2材料，可控合成出不同空腔结构及(001)晶面暴露的TiO2光催化剂，研究了不同结构及特殊晶面暴露对污染物的降解行为。空腔结构通过对光的多次反射可提高光的利用率，而具有(001)面暴露的纳米片可提供更多活性位，有助提高光催化活性。(2) 利用不同异质结材料与(001)面暴露核壳结构TiO2进行复合，分别制备出g-C3N4/TiO2、ZrO2/TiO2和TiO2/WO3复合材料。复合后不影响材料本身多级结构对光的富集作用，可与TiO2形成良好异质结，起到拓展光吸收范围、提高光生电子空穴对分离效率及促进光催化作用的效果。复合材料可有效光催化降解乙醛，稳定性强，具有一定应用价值。 (3) 利用原位醇热法制备出TiO2彩色薄膜，并通过改变生长条件控制和调变TiO2彩色薄膜的结构参数，研究了TiO2彩色薄膜的结构和色彩的关系。不同TiO2薄膜对与其颜色相匹配的入射光具有光场增强效应，有利于主客体材料光利用率的增加。进一步采用化学气相沉积法将g-C3N4沉积在TiO2彩色薄膜，可以使光耦合进波导层进行横向传播从而实现对特定波段的可见光的富集，进一步提高薄膜对可见光的利用率。