Hosseinpour Saman, Tang Fujie, Wang Fenglong, Livingstone Ruth A, Schlegel Simon J, Ohto Tatsuhiko, Bonn Mischa, Nagata Yuki, Backus Ellen H G
Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research , Ackermannweg 10, 55128, Mainz, Germany.
International Center for Quantum Materials, Peking University , 5 Yiheyuan Road, Haidian, Beijing 100871, China.
J Phys Chem Lett. 2017 May 18;8(10):2195-2199. doi: 10.1021/acs.jpclett.7b00564. Epub 2017 May 4.
The interfacial structure of water in contact with TiO is the key to understand the mechanism of photocatalytic water dissociation as well as photoinduced superhydrophilicity. We investigate the interfacial molecular structure of water at the surface of anatase TiO, using phase-sensitive sum frequency generation spectroscopy together with spectra simulation using ab initio molecular dynamic trajectories. We identify two oppositely oriented, weakly and strongly hydrogen-bonded subensembles of O-H groups at the superhydrophilic UV irradiated TiO surface. The water molecules with weakly hydrogen-bonded O-H groups are chemisorbed, i.e. form hydroxyl groups, at the TiO surface with their hydrogen atoms pointing toward bulk water. The strongly hydrogen-bonded O-H groups interact with the oxygen atom of the chemisorbed water. Their hydrogen atoms point toward the TiO. This strong interaction between physisorbed and chemisorbed water molecules causes superhydrophilicity.
与二氧化钛（TiO）接触的水的界面结构是理解光催化水分解以及光致超亲水性机制的关键。我们使用相敏和频振动光谱以及基于从头算分子动力学轨迹的光谱模拟，研究锐钛矿型TiO表面水的界面分子结构。我们发现在超亲水的紫外辐照TiO表面，存在两个取向相反、氢键作用强弱不同的O-H基团子集合。氢键作用弱的O-H基团的水分子在TiO表面化学吸附，即形成羟基，其氢原子指向本体水。氢键作用强的O-H基团与化学吸附水的氧原子相互作用。它们的氢原子指向TiO。物理吸附和化学吸附水分子之间的这种强相互作用导致了超亲水性。
