利用相位敏感的和频振动光谱研究TiO2/水溶液界面水结构

TiO2在光解水制氢、水的净化及自清洁等方面展现了巨大的应用潜力。在这些应用中，均有水的参与。深入研究TiO2与水的相互作用，了解界面处水的结构，将对TiO2更广泛的应用起到促进作用。目前，大多数相关实验是在气相或超高真空环境下进行的，而与TiO2相关的很多反应是在溶液中发生的。因此亟需实际应用环境下的表面探测手段。本项目拟利用相位敏感的和频振动光谱技术探测液相环境下的TiO2表面水结构。该技术有高界面选择性与分子选择性，可以工作在光到达的任何界面，是研究TiO2/水溶液界面的理想手段。通过对O-H伸缩振动的相位敏感的和频测量，配合不同偏振组合的分析，我们可以获取TiO2表面水的氢键状态，分子取向及水与TiO2的相互作用等诸多信息。通过改变溶液pH、TiO2晶面及紫外光照，探讨这些重要因素对表面水结构的影响。该研究将有助于理解发生在TiO2/水溶液界面处的物理、化学反应机理。

Titanium dioxide (TiO2) has shown its great potential in water splitting, water purification and self-cleaning. In these applications, water is involved. The wide application of TiO2 will be benefited from a deep understanding about the water-TiO2 interaction and interfacial water structure. To date, most relative studies were conducted in gas phase or in UHV condition, while most real reactions are occurred in aqueous. Therefore, a surface probe which can work in real reaction conditions is necessary. In this project, we propose using phase-sensitive sum frequency vibrational spectroscopy (PS-SFVS) to study the interfacial water structure at the TiO2 /aqueous interface. This technique has a feature of high interfacial and molecular selectivity and can work at any interfaces where light can reach. So it is an ideal method for the study of TiO2/aqueous interface. By doing PS-SFVS measurement and polarization analysis on O-H stretch modes, one can obtain the information such as the status of hydrogen bond, water molecule orientation and the interaction between water and TiO2. Moreover, by changing solution pH, TiO2 facets and UV irradiation which are important parameters for photocatalytic reactions, we can discuss their effects on the interfacial water structure. The study will be very helpful for understanding the physical/chemical reactions occurred at TiO2/aqueous interface.