Ferroelectric polarization is a promising tool in catalysis ( 4– 11), offering the option of spatial charge separation of photochemical reactions ( 12– 14), tuning the bonding strength of adsorbates, and shifting scaling relations. B is typically a transition metal, and its ferroelectric displacement is associated with changes in bonding angles and orbital hybridization, hence electronic and chemical properties ( 3).

It is often present in perovskites (general formula ABO 3) ( 1), where the polarization predominantly stems from the displacement of the octahedrally coordinated B atoms ( 2). These results pinpoint how adsorption states couple to ferroelectric polarization.įerroelectricity is the ability of materials to spontaneously adopt electric polarization. Temperature-programmed desorption shows substantially stronger binding of the charged CO in density functional theory calculations, the excess charge favors a bipolaronic configuration coupled to the CO. TaO 2 terraces host two distinct types of CO molecules, adsorbed at equivalent lattice sites but charged differently as seen in atomic force microscopy/scanning tunneling microscopy. At TaO 2 terraces, the polarity-compensating excess electrons form a two-dimensional electron gas and can also localize by coupling to ferroelectric distortions. This intrinsically polar material cleaves along (001) into KO- and TaO 2-terminated surface domains. How this affects individual adsorbed molecules is shown for the incipient ferroelectric perovskite KTaO 3.

Their surfaces entangle the dielectric polarization with surface polarity, excess charge, and orbital hybridization. Polarizable materials attract attention in catalysis because they have a free parameter for tuning chemical reactivity.

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