Ferroelectrics: A pathway to switchable surface chemistry and catalysis

Abstract

It has been known for more than six decades that ferroelectricity can aect a material's surface physics and chemistry thereby potentially enhancing its catalytic properties. Ferroelectrics are a class of materials with a switchable electrical polarization that can aect surface stoichiometry and electronic structure and thus adsorption energies and modes; e.g., molecular versus dissociative. Therefore, ferroelectrics may be utilized to achieve switchable surface chemistry whereby surface properties are not xed but can be dynamically controlled by, for example, applying an external electric eld or modulating the temperature. Several important examples of applications of ferroelectric and polar materials in photocatalysis and heterogeneous catalysis are discussed. In photocatalysis, the polarization direction can control band bending at water/ferroelectric and ferroelectric/semiconductor interfaces, thereby facilitating charge separation and transfer to the electrolyte and enhancing photocatalytic activity. For gas-surface interactions, available results suggest that using ferroelectrics as supports for catalytically active transition metals and oxides is another way to enhance catalytic activity. Finally, the possibility of incorporating ferroelectric switching into the catalytic cycle itself is described. In this scenario, a dynamic collaboration of two polarization states can be used to drive reactions that have been historically challenging to achieve on surfaces with xed chemical properties (e.g., direct NO x decomposition and the selective partial oxidation of methane). These predictions show that dynamic modulation of the polarization can help overcome some of the fundamental limitations on catalytic activity imposed by the Sabatier principle.

Surface-screening mechanisms in ferroelectric thin films and their effect on polarization dynamics and domain structures

“…Furthermore, one must be careful to distinguish electrostatic effects from those resulting from differences in surface structure, as noted in Ref. [155] Similar studies by Garra…”

Finite field methods for the supercell modeling of charged insulator/electrolyte interfaces

“…A priority for us is of course extending our studies of the catalytic activity of uncharged transition metal oxides [80] to negatively charged surfaces at high pH. A further topic where these computational methods can contribute, is understanding the effect of an electrolyte on ferroelectric and polar surfaces [84][85][86].…”

Surface reconstructions and related local properties of a BiFeO3 thin film

“…The atomic, electronic and magnetic properties of such surfaces can differ significantly from one group to the other1678915161718. In ferroelectric oxides, surfaces can also be charged or uncharged depending on the orientation of the surface plane with respect to the spontaneous polarization P s , resulting in a strong influence on surface structure and properties192021. For instance, surface chemistry and surface adsorption/desorption behavior in important ferroelectrics such as BaTiO 3 (BTO) and Pb(Zr,Ti)O 3 (PZT) are highly dependent on P s 1921.…”

“…In ferroelectric oxides, surfaces can also be charged or uncharged depending on the orientation of the surface plane with respect to the spontaneous polarization P s , resulting in a strong influence on surface structure and properties192021. For instance, surface chemistry and surface adsorption/desorption behavior in important ferroelectrics such as BaTiO 3 (BTO) and Pb(Zr,Ti)O 3 (PZT) are highly dependent on P s 1921. Although BTO and PZT are polarized along the tetragonal [001] axis at room temperature, it should be noted that the (001) surfaces of these structures, terminated by either a BaO or a TiO 2 plane, are charge neutral.…”