Ferroelectric surface chemistry: First-principles study of the PbTiO3 surface

Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Ferroelectric surfaces provide a promising method for modifying surface reactions via an external electric field, which can potentially provide an avenue for tunable molecular binding and surface catalysis. Using first-principles density functional theory, we investigate how the properties of the PbTiO 3 surface vary with polarization and how these changes affect CO 2 and H 2 O adsorption. We find that the polarized stoichiometric surfaces cancel the depolarizing field with an electronic reconstruction, which has a large effect on molecular binding energies. However, thermodynamically, the system will instead cancel the depolarizing field by adjusting the surface stoichiometry. Variation of the polarization and the environmental conditions can thus be used to systematically tune the surface chemistry over a wide range. In addition, we consider the addition of several different catalytic monolayers to the PbTiO 3 surface, and we find that additional surface layers can be used to modify the binding of molecules to the surface while still responding to the polarization of the substrate.