银硼（Ag,B)共掺杂TiO2光催化剂活性增强机制的固体核磁共振实验和量化计算研究

It has been found that (Ag, B)-codoped TiO2 photocatalysts exhibit an exceptionally high activity toward photocatalytic oxidation of methylene blue (MB) and rhodamine B (RhB) under visible-light or solar light irradiation, compared with solely (B- or Ag-) doped, and pure TiO2 catalysts. To gain new insights into the structure-activity rlationship, the structure, distribution, and formation mechanism of Ag and B species in the TiO2 photocatalysts will be investigated by advanced solid-state NMR technology (such as multi-quantum (MQ) MAS NMR techniques, double-quantum (DQ) correlation NMR techniques, and double-resonance experiments, etc.) in conjunction with density functional theory (DFT) calculations. Combined with the experiments of photocatalytic activity measured by UV-Vis spectrophotometry and GC-MS, the mechanism of Ag/B synergy can be clarified. To reveal the active site on the surface of the photocatalysts, the adsorption and conversion of the reactants will be studied by the 13C and 17O in-situ solid state NMR techniques, which can be used to track the pathway of photocatalytic oxidation of VOCs, such as alkene, carboxylic acid, and aldehyde. Based on the intermediates and products observed in the in-situ NMR experiments, the transition states of the reaction can be studied by theory calculations, which will reveal the molecular-level mechanism of the catalytic reactions on the (Ag, B)-codoped TiO2. All these findings are expected to be the basis for designing new TiO2-based photocatalytic materials with high activity and good stability.

(Ag,B)共掺杂TiO2是一类新型的光催化材料，其在可见光和太阳光下均表现出良好的光催化活性。本项目拟采用先进的固体NMR技术（多量子、双量子和双共振等技术）结合其它实验手段和量化计算研究该催化剂中活性Ag/B物种的微观结构、分布及其形成机制。结合紫外-可见分光光度法和GC-MS技术探索不同微观结构对光催化性能的影响机制，明确活性物种Ag/B在光催化反应过程中的协同机制。利用原位固体核磁共振技术跟踪有机小分子催化氧化反应历程，观测反应物的在催化剂表面的吸附和转化，揭示催化反应活性位点；结合实验所观测到的中间体以及产物对反应过渡态进行理论计算，从分子水平上阐明(Ag,B)共掺杂TiO2上光催化反应的机理，揭示催化剂活性增强的微观本质，为合成活性高、稳定性好的TiO2光催化材料提供依据。

本项目中(Ag, B)共掺杂TiO2是一类新型的光催化材料，其在可见光和太阳光下均表现出良好的光催化活性。我们采用了先进的固体NMR技术（多量子、双量子和双共振等技术）结合其它实验手段和量化计算研究该催化剂中活性Ag/B物种的微观结构、分布及其形成机制。结合紫外-可见分光光度法和GC-MS技术探索不同微观结构对光催化性能的影响机制，明确活性物种Ag/B在光催化反应过程中的协同机制。不但如此，通过研究还发现间隙位B元素掺杂可以稳定和调节TiO2催化剂表面层的Ti3+物种，使得该催化剂在光解水制备氢气的反应中具有极高的活性。利用原位固体核磁共振技术跟踪了光解水制备氢气反应中，甲醇和水的反应历程，观测了这些反应物的在催化剂表面的吸附和转化，揭示了TiO2光催化剂的活性位点；结合实验所观测到的中间体以及产物对反应过渡态进行理论计算，从分子水平上阐明了TiO2上光催化反应的机理，揭示催化剂活性增强的微观本质，为合成活性高、稳定性好的TiO2光催化材料提供依据。