CeO2(111)表面甲醇的光化学性质研究

CeO2 is an important rare earth metal oxide material. In recent years, the development of photocatalytic properties of CeO2 has become a research focus. However, studies on surface photocatalysis of CeO2 mainly focus on the catalytic efficiency of the model system and engineering studies, while studies on micro-photochemical reaction mechanism are still lacking. This work is proposed based on ultra-high vacuum interconnection of molecular beam epitaxy growth CeO2(111)/Ru(0001) single crystal thin film as the research object. A variety of characterization methods such as STM，XPS，TPD are used to study the perspective of microscopic mechanism of CeO2 photochemistry, including whether coverage of methanol and exposure time of light improves dissociation of different chemical bonds (C–H, O-H, C-O) differently and whether the photochemical reaction path, product and rate of methanol on the surface caused by this are different from that of pure thermochemistry. This project is expected to provide a mechanical basis for the selection and preparation of CeO2 catalyst in the practical application process of photocatalysis such as photocatalytic pollutant degradation. As well as Find a new method to study the microscopic reaction mechanism of actinide materials by using Ultra high vacuum interconnection and in-situ characterization technology.

CeO2是一种重要的稀土金属氧化物材料，近年来CeO2光催化性能开发更是成为领域研究的热点。然而，CeO2表面光催化研究主要集中在模型体系催化效率和工程类研究方面，而在微观光化学反应机理研究还较为缺乏。本项目拟采用超高真空互联多手段原位制备-表征技术，使用分子束外延生长CeO2(111)/Ru(0001)单晶薄膜为研究对象，STM，XPS，TPD等多种表征手段结合，研究CeO2光催化微观反应机理。具体包括甲醇吸附量和光照时间对甲醇分子不同化学键(C-H、O-H、C-O)断键解离是否存在不同的促进作用，由此导致的甲醇在表面的光化学反应路径、产物和速率与单纯的热化学相比又有着怎样的异同。希望通过该项目研究为光催化污染物降解等光催化实际应用过程中CeO2催化剂的选择和制备提供机理性依据，同时探索将超高真空互联多手段原位表征研究技术发展到锕系材料的微观反应机理研究中的新方法。

CeO2是一种重要的稀土金属氧化物材料，近年来CeO2光催化性能开发更是成为领域研究的热点。然而，CeO2表面光催化研究主要集中在模型体系催化效率和工程类研究方面，而在微观光化学反应机理研究还较为缺乏。本项目拟采用超高真空互联多手段原位制备-表征技术，通过STM，ARPES，UPS等研究手段研究了甲醇/CeO2表面的光化学反应性质。我们发现不同甲醇吸附量经过0.5h光照后，带隙态的谱重基本相同，说明该体系下甲醇的光化学解离与吸附量关系不大。通过 光照时间的实验，我们得出了甲醇在CeO2单晶表面的化学反应过程：甲醇在CeO2单晶表面吸附后会先出现极小部分的解离，之后随光照时间增长，甲醇的O-H键被活化，解离量逐渐增大形成甲氧基和羟基，之后随着进一步的光照，甲醇的C-H键被活化，生成新的产物，我们通过特征峰位置和带隙态密度变化推测新产物为甲醛。该项目的研究不仅为CeO2光化学反应机理提供了实验依据，还探索了镧系锕系元素氧化物表面光化学反应的研究方法，为后续国防领域锕系材料的相关研究奠定了基础。