Adsorption and dissociation of water on Zr(0001) with density-functional theory studies

TL;DR

This study uses density-functional theory to investigate how water molecules adsorb and dissociate on Zr(0001) surfaces, revealing stable configurations, mobility, and dissociation pathways relevant to zirconium corrosion.

Contribution

First theoretical analysis of water adsorption and dissociation on Zr(0001) surface using DFT, identifying stable states and mechanisms.

Findings

Water is highly mobile on Zr(0001) surface.

Dissociation of water is facile, especially in upright configuration.

Adsorption involves specific orbital interactions and charge transfer.

Abstract

The adsorption and dissociation of isolated water molecule on Zr(0001) surface are theoretically investigated for the first time by using density-functional theory calculations. Two kinds of adsorption configurations with almost the same adsorption energy are identified as the locally stable states, i.e., the flat and upright configurations respectively. It is shown that the flat adsorption states on the top site are dominated by the 1$b_{1}$-$d$ band coupling, insensitive to the azimuthal orientation. The diffusion between adjacent top sites reveals that the water molecule is very mobile on the surface. For the upright configuration, we find that besides the contribution of the molecular orbitals 1$b_{1}$ and 3$a_{1}$, the surface$\rightarrow$water charge transfer occurring across the Fermi level also plays an important role. The dissociation of H$_{2}$O is found to be very facile, especially for the upright configuration, in good accordance with the attainable experimental results. The present results afford to provide a guiding line for deeply understanding the water-induced surface corrosion of zirconium.