The bonded interfacial layer structure of α-Al2O3 (0001)/water at different pH values studied by sum frequency vibrational spectroscopy

Shumei Sun; Huanzhen Yao; Jiabao Pan; Zhenzhe Xian

doi:10.1063/5.0235695

The bonded interfacial layer structure of α-Al2O3 (0001)/water at different pH values studied by sum frequency vibrational spectroscopy

J Chem Phys. 2024 Dec 7;161(21):214708. doi: 10.1063/5.0235695.

Authors

Shumei Sun^{1

2

3}, Huanzhen Yao^{1

2}, Jiabao Pan^{1

2}, Zhenzhe Xian^{1

2}

Affiliations

¹ School of Physics and Astronomy, Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China.
² Key Laboratory of Multiscale Spin Physics, Ministry of Education, Beijing Normal University, Beijing 100875, China.
³ Key Laboratory of Micro and Nano Photonic Structures (MOE), Fudan University, Shanghai 200433, China.

PMID: 39641355
DOI: 10.1063/5.0235695

Abstract

Oxide/water interfaces are ubiquitous, with alumina/water drawing particular interest due to its environmental and industrial applications. Understanding the interfacial structure at the molecular level is crucial for many physical and chemical processes occurring there. However, the exact structure of interfacial H-bonded network at different pH values remains unclear. Here, sum-frequency vibrational spectroscopy in the OH stretch region was employed to study α-Al2O3 (0001)/water interface at different pH values, while suppressing the contribution of the diffusion layer by adding salts. The experimental results revealed although the variation of pH can charge the surface, it has little impact on the structure of the bonded interfacial layer (BIL). The interaction between alumina and water is mainly governed by weak hydrogen bonds. Furthermore, the templating effect of α-Al2O3 (0001) on the interfacial H-bonded network was observed, with the O-H stretch mode of ∼3430 cm-1 exhibiting anisotropy consistent with the (0001) surface symmetry. These findings indicate that the BIL structure on Al2O3 (0001) is predominantly influenced by the surface atom configuration, and the effect of charge changes induced by pH on the BIL structure is negligible.