能有效利用光生载流子的反应体系与光催化材料的耦合设计及其本质规律研究

In this project, a series of semiconductor photocatalytic materials are designed and fabricated to take full advantage of its photogenerated carriers and realize simultaneously selective oxidation and reduction of organic matters or photocatalytic hydrogen evolution from water, which achieves an effective combination of reaction system and photocatalytic materials. Herein, a range of photocatalysts based on the rare earth sulfide would be prepared by compositing many narrow-band gap semiconductor materials (e.g., CdIn2S4, ZnCdS2, ZnIn2S4) or direct synthesis of rare earth composite sulfide, and manipulating its light-absorption properties and surface electron distribution with mono- or bi-metallic Au(Ag)@Pt core-shell structure. It focuses on the effects of preparation parameters on the composition, chemical and coordination state of its surface atoms or ions, local micro-structure of photocatalytic materials, the positions of its valence band and conduction band, and photocatalytic performance, thus revealing the relationship between the micro-structure and texture of the photocatalytic materials and their positions of valence band and conduction band, and the inherent and essential law between the photogenerated electron-hole pairs of photocatalysts and the coupled reactions of selective oxidation and reduction of organic matters or photolysis of water. The internal natural characteristics for regulation of selective oxidation and reduction of organics or photocatalytic hydrogen evolution are expounded. Thereby, it further reveals the essential law of the effective combination of reaction system and photocatalytic materials. This study could offer an important theoretical and practical value for the design and development of photocatalytic materials and the photocatalytic transformation of organic matters.

本项目设计制备出能同时利用光生载流子实现有机物选择性氧化和还原或直接产氢的光催化材料，实现反应体系与光催化材料的有效耦合。以稀土元素的硫化物半导体作为基质，通过与窄带隙的硫化物半导体材料CdIn2S4、ZnCdS2、ZnIn2S4复合或直接合成稀土元素的复合硫化物，采用单金属或双金属壳核Au(Ag)@Pt等贵金属修饰调控催化剂的光吸收和表面电子分布，制备出有效的光催化材料。重点研究制备参数等对光催化材料的组成、表面原子或离子的状态、局域微结构、价带和导带位等及光催化性能的影响；揭示光催化材料的微观结构、织构等与其价带和导带位的关系，揭示光生电子和空穴与实现有机物选择性氧化和还原或直接产氢的内在本质规律，阐明调控有机物选择性光催化氧化和还原或产氢的内在本质特征，进而揭示反应体系与光催化材料有效耦合的本质规律。该研究对丰富光催化材料的设计、制备及有机物光催化转换合成都有重要的理论和实际价值。

本项目中，成功制备出能有效分离光生载流子并高效驱动有机物的选择性氧化和还原或直接产氢的光催化材料，并实现了反应体系与光催化材料的有效耦合的预期目标。光催化剂的制备采用稀土元素的硫化物半导体作为基质，通过与窄带隙的硫化物半导体材料CdS、CdLa2S4、CdIn2S4、Zn3In2S6、ZnIn2S4等复合或直接合成稀土元素的复合硫化物，并采用贵金属（如Au、Pt和Au@Pt）以及非贵金属的磷化物（如Ni2P、MoP等）或硫化物（NiS、MoS2）等调控催化剂的光吸收和表面电子分布，制备出了一系列高效的光催化材料。详细研究了制备参数等对光催化材料的组成、表面原子或离子的状态、局域微结构、价带和导带位等及光催化性能的影响；揭示了光催化材料的组成及结构等与同时实现选择性芳香醇氧化和硝基苯还原或直接产氢的内在本质特征及规律。研究发现光催化剂的价带位和导带位是影响光催化选择性氧化芳香醇至芳香醛和还原硝基苯到苯胺或直接产氢最重要因素。光生空穴是芳香醇选择性脱氢至芳香醛的氧化剂，脱氢产生的H质子协同光生电子选择性还原硝基苯到苯胺或直接产氢，而其它反应过程中检测到的活性种类起的作用均很小。通过该项目筛选出反应体系与上述光催化材料的有效耦合。通过研究芳香醇至芳香醛选择性氧化机理、还原硝基苯到苯胺或产氢的还原机理，通过光生电子和空穴的有效利用率和芳香醛和苯胺或氢的生成量间的关系等，最终阐明了有机物选择性氧化和还原的反应机理。该项目对适用于同体系中有机物同时选择性氧化和还原或直接产氢的光催化材料的筛选、设计、制备以及应用范围的拓展都有重要的理论及实际价值。