Water adsorption on amorphous silica surfaces: A Car-Parrinello simulation study

TL;DR

This study combines classical and ab initio molecular dynamics to investigate water adsorption on amorphous silica surfaces, revealing reaction mechanisms and energy profiles at room temperature.

Contribution

It introduces a hybrid simulation approach to analyze water-silica interactions, providing detailed reaction pathways and energetic insights.

Findings

Water reacts with two-membered silica rings forming silanol groups

The reaction is exothermic with a quantifiable activation energy

Simulations reveal detailed reaction mechanisms at 300K

Abstract

A combination of classical molecular dynamics (MD) and ab initio Car-Parrinello molecular dynamics (CPMD) simulations is used to investigate the adsorption of water on a free amorphous silica surface. From the classical MD SiO_2 configurations with a free surface are generated which are then used as starting configurations for the CPMD.We study the reaction of a water molecule with a two-membered ring at the temperature T=300K. We show that the result of this reaction is the formation of two silanol groups on the surface. The activation energy of the reaction is estimated and it is shown that the reaction is exothermic.