Enhancing alpha-Fe2O3(0001) surfaces reactivity through lattice-strain control

In-plane strain-engineered water adsorption on Fe- and O-3-terminated alpha-Fe2O3(0 0 0 1) surfaces was investigated using dispersion corrected density functional theory. We found that in order to enhance the water adsorption capacity different type of in-plane strain is needed to be applied on the two surfaces. On Fe-terminated surface increasing compressive strain facilitates water molecular adsorption. We demonstrate that this result mainly comes from the structural behavior of the outmost Fe cation on clean Fe-terminated surface. On the contrary, inplane tensile strain favors water adsorption and dissociation on the O-3-terminated surface. We discuss in details the possible reasons of this difference between the two surfaces in terms of structural parameters. Furthermore, we found that the two surfaces can represent two competitive molecular adsorption sites at a certain tensile strain in mixed surfaces. Finally, while strain is found to have a wide influence on the dissociation of water on the O-3 termination, its effect is less pronounced on the Fe terminated one. According to our results strain-engineering on hematite surfaces represents a feasible way to enhance the reactivity.