Article pubs.acs.org/JPCC
Water Film Adsorbed on the α‑Al2O3(0001) Surface: Structural Properties and Dynamical Behaviors from First-Principles Molecular Dynamics Simulations Shang-Yi Ma,† Li-Ming Liu,*,‡,§ and Shao-Qing Wang† †
Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China ‡ Beijing Computational Science Research Center, Chinese Academy of Engineering Physics, Beijing 100084, China § Chengdu Green Energy and Green Manufacturing Technology R&D Center, Chengdu 610207, China ABSTRACT: We investigated the structural properties, dynamical behaviors, and vibrational spectra of the water film adsorbed on the Al-terminated αAl2O3(0001) surface using first-principles molecular dynamics simulations. The simulations showed that the structural properties of the water film, such as the mass density, atom number density, orientation order and hydrogen bonds (HBs) of water molecules, are considerably affected by the Alterminated α-Al2O3(0001) surface along its normal direction. A new dissociation 1−4′ state via two different indirect and double indirect pathways was proposed, which is slightly more favorable than 1−4 state under the condition of multiple water layers. The blue- and red-shifting of vibrational spectra for different water layers was observed. The interfacial water in various adsorption configurations and its corresponding vibrational spectrum were explicitly identified. The “ice-like” and “liquid-like” peaks of vibrational spectra, which are observed in various experiments of water/hydroxylated αAl2O3(0001) interface, were reproduced in our simulations. Our simulations suggest the “ice-like” peak mostly stems from the surface OH and the interfacial water molecules that experienced more HBs interactions, while the “liquid-like” peak results from the “liquid-like” water molecules. Our study provides novel insights into the complex structures and dynamical behaviors of interfacial water, upon water film adsorbing on the Al-terminated α-Al2O3(0001) surface.
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