Hydroxylation Structure and Proton Transfer Reactivity at the Zinc Oxide-Water Interface
David Raymand, Adri C. T. van Duin, William A. Goddard III, Kersti Hermansson, Daniel Spångberg
Abstract
The hydroxylation structural features of the first adsorption layer and its connection to proton transfer reactivity have been studied for the ZnO-liquid water interface at room temperature. Molecular dynamics simulations employing the ReaxFF forcefield were performed for water on seven ZnO surfaces with varying step concentrations. At higher water coverage a higher level of hydroxylation was found, in agreement with previous experimental results. We have also calculated the free energy barrier for transferring a proton to the surface, showing that stepped surfaces stabilize the hydroxylated state and decrease the water dissociation barrier. On highly stepped surfaces the barrier is only 2 kJ/mol or smaller. Outside the first adsorption layer no dissociation events were found during almost 100 ns of simulation time; this indicates that these reactions are much more likely if catalyzed by the metal oxide surface. Also, when exposed to a vacuum, the less stepped surfaces stabilize adsorption beyond monolayer coverage.
Group Members
Raymand, D., Duin, A. C. T. v., III, W. A. G., Hermansson, K., & Spångberg, D. (2011). Hydroxylation Structure and Proton Transfer Reactivity at the Zinc Oxide-Water Interface. *J. Phys. Chem. C*, *115*(17), 8573-8579. https://doi.org/10.1021/jp106144p