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Hydrogen Bonds and H3O+ Formation at the Water Interface with Formic Acid Covered Anatase TiO2
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2021-07-19 , DOI: 10.1021/acs.jpclett.1c01886
Bo Wen 1, 2 , Annabella Selloni 1
Affiliation  

Carboxylic acid-modified TiO2 surfaces in aqueous environment are of widespread interest, yet atomic-scale understanding of their structure is limited. We here investigate formic acid (FA) on anatase TiO2 (101) (A-101) in contact with water using density functional theory (DFT) and ab initio molecular dynamics (AIMD). Isolated FA molecules adsorbed in a deprotonated bridging bidentate (BD) form on A-101 are found to remain stable at the interface with water, with the acid proton transferred to a surface oxygen to form a surface bridging hydroxyl (ObrH). With increasing FA coverage, adsorbed monolayers of only BD and successively of alternating monodentate (MD) and BD species give rise to a higher concentration of surface ObrH’s. Simulations of these adsorbed monolayers in water environment show that some protons are released from the surface ObrH’s to water resulting in a negatively charged surface with nearby solvated H3O+ ions. These results provide insight into the complex acid–base equilibrium between an oxide surface, adsorbates and water and can also help obtain a better understanding of the wetting properties of chemically modified TiO2 surfaces.

中文翻译:

与甲酸覆盖的锐钛矿型 TiO2 在水界面形成氢键和 H3O+

水性环境中羧酸改性的 TiO 2表面受到广泛关注,但对其结构的原子级理解有限。我们在这里使用密度泛函理论 (DFT) 和从头分子动力学 (AIMD) 研究与水接触的锐钛矿 TiO 2 (101) (A-101 ) 上的甲酸 (FA )。发现以去质子化的双齿 (BD) 形式吸附在 A-101 上的分离的 FA 分子在与水的界面处保持稳定,酸性质子转移到表面氧以形成表面桥连羟基 (O br H)。随着 FA 覆盖率的增加,仅 BD 的吸附单层以及交替的单齿 (MD) 和 BD 物种会产生更高浓度的表面 O brH的。水环境中这些吸附单分子层的模拟表明,一些质子从表面 O br H释放到水中,导致带负电荷的表面与附近的溶剂化 H 3 O +离子。这些结果提供了对氧化物表面、吸附物和水之间复杂酸碱平衡的深入了解,也有助于更好地了解化学改性 TiO 2表面的润湿性能。
更新日期:2021-07-29
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