Sun Huijuan, Zheng Qijing, Lu Wencai, Zhao Jin
College of Physics and State Key Laboratory of Bio-Fibers and Eco-Textiles, Qingdao University, Qingdao, Shandong 266071, People's Republic of China.
J Phys Condens Matter. 2019 Mar 20;31(11):114004. doi: 10.1088/1361-648X/aafcf6. Epub 2019 Jan 9.
Solvated electrons are known to be the lowest energy charge transfer pathways at oxide/aqueous interface and the understanding of the electron transfer dynamics at the interface is fundamental for photochemical and photocatalytic processes. Taking anatase TiO/HO interface as a prototypical system, we perform time-dependent ab initio nonadiabatic molecular dynamics calculations to study the charge transfer dynamics of solvated electrons. For the static electronic properties, we find that the dangling H atoms can stabilize solvated electrons. A solvated electron band can be formed with one monolayer HO adsorption. The energies of the solvated electron band minimum (SEBM) decrease when HO adsorbs dissociatively. Moreover, the surface oxygen vacancies are also helpful for stabilizing the solvated electron band. For the dynamics behaviour, we find that the ultrafast charge transfer from SEBM to anatase TiO (1 0 1) surface at 100 K is mainly contributed by nonadiabatic mechanism. Comparing with rutile TiO (1 1 0) surface, the lifetime of solvated electron on anatase TiO (1 0 1) surface is longer, suggesting a better photocatalytic properties. Our results provide essential insights into the understanding of the charge transfer dynamics and the possible photocatalytic mechanism at oxide/aqueous interface.
已知溶剂化电子是氧化物/水界面处能量最低的电荷转移途径，而理解该界面处的电子转移动力学对于光化学和光催化过程至关重要。以锐钛矿TiO₂/H₂O界面作为典型体系，我们进行了含时从头算非绝热分子动力学计算，以研究溶剂化电子的电荷转移动力学。对于静态电子性质，我们发现悬空的H原子能够稳定溶剂化电子。单层H₂O吸附时可形成溶剂化电子能带。当H₂O发生解离吸附时，溶剂化电子能带最小值（SEBM）的能量降低。此外，表面氧空位也有助于稳定溶剂化电子能带。对于动力学行为，我们发现在100 K时，从SEBM到锐钛矿TiO₂(1 0 1)表面的超快电荷转移主要由非绝热机制贡献。与金红石TiO₂(1 1 0)表面相比，溶剂化电子在锐钛矿TiO₂(1 0 1)表面的寿命更长，这表明其具有更好的光催化性能。我们的结果为理解氧化物/水界面处的电荷转移动力学及可能的光催化机制提供了重要见解。
