The dissociated amorphous silica surface: Model development and evaluation

Ali A. Hassanali, Hui Zhang, Chris Knight, Yun Kyung Shin, Sherwin J. Singer

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

At pH 7, amorphous silica has a characteristic negative charge due to the deprotonation of silanol groups on the surface. Electrokinetic phenomena and transport of biomolecules in devices depend sensitively on the surface morphology, distribution of ions and solvent, and adsorption properties of solutes close to the surface in the electrical double layer region. Hence, simulation of these phenomena requires detailed atomistic models of the double layer region. In this Article, we extend our undissociated silica surface model [J. Phys. Chem. B 2007, 111, 11181-11193] to include dissociated Si-O - groups, which interact with both water and salt (Na+ and Cl-). We have also conducted ab initio molecular dynamics (AIMD) simulations of a smaller system consisting of a hydrated silica slab. The radial distribution functions predicted by the empirical model are in qualitative agreement with those from the AIMD simulations. The hydrophobic and hydrophilic nature of silanol-poor and silanol-rich regions of the amorphous silica surface observed in our empirical model is reproduced in the AIMD simulations of the smaller slab. In the initial stages of our AIMD simulations, we observe various chemical processes that represent different hydroxylation mechanisms of the surface.

Original languageEnglish (US)
Pages (from-to)3456-3471
Number of pages16
JournalJournal of Chemical Theory and Computation
Volume6
Issue number11
DOIs
StatePublished - Nov 9 2010

All Science Journal Classification (ASJC) codes

  • Computer Science Applications
  • Physical and Theoretical Chemistry

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