有序大孔高比表面铋系氧化光催化材料的合成与应用研究

The development of photocatalysts for organic synthesis is far from being mature. It is common to face drawbacks such as poor efficiency in the absorption of visible light and unsatisfactory activity. It is observed that most of the bismuth-based photocatalysts show a broad range of visible light absorption as well as strong oxidation ability. Through the design and construction of three-dimensionally ordered macroporous (3DOM) bismuth-containing semiconductors, and with insights into the fabrication mechanism, it is envisaged that photocatalysts highly efficient for the activation and transformation of C-H bonds can be developed. The target of the proposed project is to synthesize bismuth-containing photocatalysts that are not only high in visible-light photocatalytic activity but also excellent in reusability. There are three key aspects in the project : (1) To synthesize 3DOM Bi-based photocatalysts using three-dimensionally ordered polymers as template; (2) To characterize the as-synthesized photocatalysts by appropriate techniques in terms of visible-light absorption property, separation ability of photo-generated charge carriers, catalyst active components, and important intermediates of reaction processes; and (3) To evaluate the performance of the photocatalysts for the activation of insert C-H bonds taking the oxidation of cyclohexane to cyclohexone as model reactions. The aim is to clarify the synergism among factors such as light absorption efficiency, catalytic behaviors, catalyst structure and morphology as well as catalyst recyclability and reusability so as to establish the related mechanisms of catalyst fabrication and photocatalytic reaction. The study has significant scientific merits and application prospects. The outcomes will provide information valuable for the design of high-efficient visible-light photocatalysts which have high application potentials in organic synthesis.

针对目前光催化有机合成催化剂存在可见光吸收弱、光催化活性低以及光催化剂种类少等问题，结合铋系半导体光催化剂具有宽光谱吸收能力、氧化能力较强的优势，本项目拟研究具有三维有序大孔结构的铋系半导体光催化材料，探讨其合成方法和机制，获得具有高可见光活性的光催化烃类有机物C-H键活化与转化的催化剂。研究重点在于高可见光吸收效率、高活性、长寿命铋系光催化剂的设计与合成。主要研究内容与思路包括：（1）通过三维有序聚合物作为结构导向剂，可控合成具有与入射可见光相匹配（产生光子效应）的三维有序大孔铋系光催化材料；（2）采用多种表征技术研究入射光吸收效率、光生载流子分离情况、催化活性位、催化反应重要中间体等；（3）探究其对烃氧化反应（主要为环己烷选择性氧化制备环己酮）的催化性能，关联催化剂组成、结构及其光吸收效率、活性、寿命之间的定性定量关系，揭示其催化机理，为研制其他可见光催化剂提供重要参考。

本项目以创制有序大孔高比表面积铋系氧化光催化材料及其制备新方法和拓展其应用为目标，创制了原位“刻蚀-再生长”法可控制备了三维有序大比表面积CdWO4/Bi2WO6、铁酸铋-MIL-53(Fe)，并将其分别应用于光催化有氧羟基化苯制备苯酚，光催化苯甲醇选择性氧化制备苯甲醛等反应中，表现出好的光催化活性；通过简单水热、溶剂热等方法，成功制备超薄Bi2MoO6纳米片、将Bi2MoO6纳米颗粒负载于二维g-C3N4表面，实现Bi2MoO6高活性位点暴露，提高其可见光下催化甲苯选择性氧化制苯甲醛、胺氧化偶联制亚胺等性能。基于三聚硫氰酸镉的可控分解过程，我们还以三聚硫氰酸镉为原料，研制了超分子自组装法可控制备了多孔双壳层CdS@C3N4、空心多孔结构ZnS-C3N4、有序多孔ZnS-CdS以及同时具有紧密异质结和表面S空位的CdS-CdIn2S4复合光催化剂；研制了以小分子咖啡酸为桥连剂，通过配位自组装法可控制备MOFs包覆BiVO4核壳结构催化材料的新方法，解决了传统方法包覆疏松不均匀的难题。已发表论文30篇，申请发明专利9件（其中三件已经授权）。承办了第四届全国青年光催化高端论坛等学术会议，项目负责人应邀参加2018年国际催化科学与技术的发展与展望研讨会（澳大利亚）等国内学术会议，并做主旨报告或分会特邀报告。