First principles molecular dynamics simulations of H2S dissociation on Fe (1 1 1) in aqueous environments.

[Display omitted] • Water aggregation configurations on Fe (1 1 1) surface were discussed. • The water adsorption layer structures on Fe (1 1 1) at different temperatures were investigated. • H 2 S dissociation paths in aqueous environment on Fe (1 1 1) at 300 K was discussed. • H 2 S dissociation behavior on clean Fe (1 1 1) at 10 K and 300 K was discussed. A wet H 2 S environment can cause significant mechanical failure and corrosion. In this study, we used first principles static and molecular dynamics calculations to investigate the behavior of water adsorption of Fe (1 1 1) at different temperatures, followed by the effect of water molecules on the dissociation of H 2 S on the Fe (1 1 1) surface. At room temperature, the structures of the water layer on the Fe (1 1 1) surface include the H-up and H-down mixed structures. H 2 S molecules exhibit stronger competitiveness in co-adsorption with water molecules. Moreover, because the interaction of H-S in H 2 S molecules can be weakened by hydrogen bonds with water and stronger Fe-H owing to water adsorption on the surface, the induced lower dissociation barriers can be sufficiently overcome at room temperature. Therefore, it can be concluded that conditions such as water adsorption layer and room temperature can promote the dissociation of H 2 S on Fe (1 1 1), which is helpful to understand the H 2 S corrosion process at the metal interface. [ABSTRACT FROM AUTHOR]