有机分子在超薄二维纳米片结构材料上的配位活化及光催化转化

To understand the active sites of photocatalysts and the mechanisms of photocatalytic organic reactions, especially the surface interactions between organic molecules and photocatalysts, this proposal aims to investigate the surface-interface properties of ultrathin 2D nanosheet structure materials in photocatalytic organic transformation. First, the possible surface states of these 2D nanosheets such as surface defects, unsaturated metal sites, hydroxyl and atomic arrangement can be elucidated by the in-situ molecular spectroscopy, 1H-NMR and XAFS. Then, by utilizing techniques such as SPM, DFT, ESR and DRS, further studies can be developed to fundamentally understand the interfacial effects of 2D materials on mechanisms of photocatalytic reaction, which could reveal the interactions between photocatalysts and reactants at molecule levels; clarify the adsorption sites, coordination mode and interface charges transfer; and explore the possible intermediate species in photocatalysis and finally confirm the active sites. Moreover, mechanisms of synergy effects between surface coordination-activation for photocatalytic reaction pathways can be determined by comparing and combining ideas of traditional electron-hole in band gap structure. This study is of both fundamental importance by revealing surface activation effects on organic photocatalytic reaction, and practical importance by providing guidance on improve catalytic activities at molecular levels.

针对光催化有机合成中催化剂的活性位点难确定，有机分子与催化剂之间作用方式和转化机理不明确等问题，本课题拟开展超薄二维材料光催化有机合成反应中的表界面研究。通过原位分子光谱、1H-NMR以及XAFS等表征手段探索材料的表面态，如缺陷、金属配位不饱和位点、表面羟基、表面原子组成及排列等。结合SPM、DFT、ESR和DRS等技术研究光催化反应过程中纳米片表界面与有机物之间的作用方式，阐明有机分子在催化材料表面的吸附位点、配位形式、界面电子传递方式等表面行为，探寻有机分子在催化转化过程中的可能中间产物，验证催化活性位点。揭示表面配位-活化在光催化有机合成中的作用，且与传统光生电子-空穴对的内部能带结构理论相结合，提出表面配位活化与光催化的协同作用机制模型。该研究不仅在分子水平上揭示了光催化反应中表界面对有机分子配位活化的重要意义，而且为分子层次上构筑和调控高效催化剂提供有价值的理论指导。

本项目选择一系列具有丰富活性位点、稳定的超薄二维纳米片（如SnNb2O6、TiO2、BiOCl、Bi2MoO6和ZnTi-LDH等）及其复合材料为光催化剂，探究了光催化剂与有机分子之间作用方式和转化机理。采用原位分子光谱、1H-NMR以及XAFS等表征手段，深入探究光催化材料的表面缺陷、配位不饱和金属位点、表面羟基、表面原子组成及排列等表面化学信息。通过SPM、DFT、ESR和DRS等技术对光催化反应中的表面界面研究，揭示芳香醇、芳香胺、卤代芳烃、芳香硝基化合物、不饱和有机物（醛、炔）等有机分子在催化材料表面的吸附位点、配位形式、界面电子传递方式等表面行为，探寻各类有机分子在催化转化过程中的可能中间产物，验证催化活性位点。揭示了表面配位-活化-催化过程在光催化有机合成中的联系和作用，结合传统光生电子-空穴能带结构理论催化机制，成功建立了表面配位活化与光催化的协同作用机制模型。这些研究结果为从分子水平深入理解光催化的本质以及调控和构筑高效超薄二维纳米片光催化剂奠定理论和实验基础。