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A water molecule dissociates and breaks a Si-O-Si bond of the glass network.

A description of the physisorption and subsequent chemisorption of water on silica glass surfaces is presented that combines electronic structure calculations with classical molecular dynamics simulations. The method associates the strength of the physisorption sites with the gradient of the electrostatic potential, and the chemical reactivity with the chemical hardness of the surface. The results are compared with those of more classical physisorption energy mappings and to ab initio calculations of water molecules physisorbing at specific sites. The mappings show that while the strongest sites for physisorption are network coordination defects, these defects are not as chemically reactive as the Na – non-bridging oxygen sites on sodium silicate glass surfaces. Hydroxylation of a silica fracture surface was shown to greatly reduce its chemical reactivity. Altogether, this approach combines the efficiency of classical molecular dynamics for structural determinations, with the chemical degrees of freedom provided by electronic structure calculations, to yield a semi-quantitative map of chemical reactivity across a surface.

This research area provides opportunities for undergraduate research.

Publications

2005 · 2012 · 2014 · All
H. Wang, M. Dellostritto, N. Kumar, P. R. C. Kent, A. Kolesnikov, J. Kubicki, D. J. Wesolowski and J. O. Sofo, "Vibrational Density of States of Strongly H-Bonded Interfacial Water: Insights from Inelastic Neutron Scattering and Theory," J. Phys. Chem. C 118, 10805 – 10813 (2014)
J. Kubicki, J. O. Sofo, A. A. Skelton and A. V. Bandura, "A New Hypothesis for the Dissolution Mechanism of Silicates," J. Phys. Chem. C 116, 17479 – 17491 (2012)
E. A. Leed, J. O. Sofo and C. Pantano, "Electronic structure calculations of physisorption and chemisorption on oxide glass surfaces," Phys. Rev. B 72, 155427 (2005)
J. O. Sofo : Water on Glass Surfaces