Department of Materials and Environmental Chemistry, Stockholm University, 10691 Stockholm, Sweden.
J Chem Phys. 2017 Jul 14;147(2):024704. doi: 10.1063/1.4991381.
Ab initio molecular dynamics simulations are reported for water-embedded TiO surfaces to determine the diffusive and reactive behavior at full hydration. A three-domain model is developed for six surfaces [rutile (110), (100), and (001), and anatase (101), (100), and (001)] which describes waters as "hard" (irreversibly bound to the surface), "soft" (with reduced mobility but orientation freedom near the surface), or "bulk." The model explains previous experimental data and provides a detailed picture of water diffusion near TiO surfaces. Water reactivity is analyzed with a graph-theoretic approach that reveals a number of reaction pathways on TiO which occur at full hydration, in addition to direct water splitting. Hydronium (HO) is identified to be a key intermediate state, which facilitates water dissociation by proton hopping between intact and dissociated waters near the surfaces. These discoveries significantly improve the understanding of nanoscale water dynamics and reactivity at TiO interfaces under ambient conditions.
我们对水嵌入 TiO 表面进行了从头分子动力学模拟，以确定完全水合状态下的扩散和反应行为。我们为六个表面（金红石(110)、(100)和(001)以及锐钛矿(101)、(100)和(001)）开发了一个三域模型，该模型将水描述为“硬”（不可逆地与表面结合）、“软”（流动性降低，但在表面附近具有取向自由度）或“体相”。该模型解释了以前的实验数据，并提供了 TiO 表面附近水扩散的详细图像。我们使用图论方法分析水的反应性，揭示了 TiO 表面在完全水合条件下除了直接水分解之外还存在多种反应途径。水合氢离子（HO）被确定为关键的中间状态，它通过质子在表面附近完整和分解的水中跳跃促进水的离解。这些发现显著提高了对环境条件下 TiO 界面纳米尺度水动力学和反应性的理解。
