新型铋系纳米光催化剂的设计、制备及其在甲苯氧化制苯甲醛中的应用研究

Most of photocatalysts developed in the past are suffering drawbacks such as visible-light absorption is weak, recombination of photogenerated charge carriers is serious, photocatalytic activity is low and so on. Considering that most of bismuth-containing photocatalysts show strong absorption in visible-light region. It is aimed to develop highly efficient (high activity, selectivity and stablilty) bismuth-containing composite photocatalysts and their applications in the selective oxidation of toluol into benzaldehyde in this project. How to design and prepare these photocatalysts will be the key research issue. The following method will be adopted in this project: (1) combine bismuth-containing photocatalysts with other semiconductors or synthesis of nonstoichiometric bismuth-containing photocatalysts to adjust its band energies to coincide with redox potential between reactants and products, (2) by creating oxygen vacancy on the surface of photocatalysts and introduce dye-sensitization process to further improve the photocatalytic activities of the composite photocatalysts, (3) by employing varied techniques to characterize the physiochemical properties (e.g., composition, band energy, vacancies on the surface, surface acidity and basicity, etc.) of the as-synthesized catalysts, (4) in situ techniques and trapping agent to capture the active sites and active species in the reaction process. We will also study the relationship between the catalytic performance and the structure of the catalysts so as to clarify the plausible reaction mechanism. It can be deduced that this project will bring about highly efficient photocatalysts for controllable preparation benzaldehyde at mild reaction conditions. Additionally, the research results will provide important information for the design of other high-efficiency photocatalysts under visible-light irradiation.

针对目前光催化剂对可见光的响应弱、光生载流子容易复合、光催化活性低等不足，结合铋系光催化剂具有可见光吸收强的特点，本项目拟开展高效铋系光催化剂的设计、制备以及其在甲苯选择性氧化制备苯甲醛中的应用研究。研究的重点是高效光催化剂的设计和制备。研究内容主要有：（1）合成具有特殊形貌的非化学计量比铋系光催化剂和构建含铋的复合光催化剂体系来调节铋系光催化剂的能带结构；（2）在催化剂表面构造氧空位、引入染料敏化过程等提高复合光催化剂的活性；（3）通过多种表征技术探究催化剂的组成、能带结构、表面性质等物理化学性质，采用原位表征技术以及活性基团捕获技术研究催化反应过程中的活性基团。关联催化剂的结构与其性能之间的定性、定量关系。本项目的成功实施，有望揭示铋系光催化剂在甲苯直接氧化制备苯甲醛过程中的催化机理，为苯甲醛的合成提供绿色可行的方法，还为合成高效可见光催化剂提供重要参考信息。

针对目前光催化剂对可见光的响应弱、光生载流子容易复合、光催化活性低等不足，结合铋系光催化剂具有可见光吸收强的特点，本项目通过含铋纳米半导体光催化材料的可控制备实现特定形貌的构建；通过掺杂、半导体的复合等实现铋系半导体光催化剂能带结构调控；通过光催化剂表/界面结构的调控实现光生载流子的高效分离，成功制备了多种具有自主知识产权的含铋纳米光催化材料；通过关联光催化剂的结构与光催化剂性能之间的构效关系，研究催化反应过程中的活性基团、反应中间产物等，对催化反应机制有了初步认识。此外，还开发了用于有机污染物降价、水分解制氢、光催化环己烷选择性氧化制备环己酮和环己醇（KA油）、光催化二苯甲酮及其衍生物合成等的高效光催化材料。本项目的成功实施，有望揭示铋系光催化剂在有机物选择性氧化过程中的催化机理，为重要有机中间体的合成提供绿色可行的方法，还为合成高效可见光催化剂提供重要参考信息。