Invited
Physical chemistry of ferroelectric oxides surfaces

Ferroelectric surfaces are amazing playgrounds for reduction and oxidation reactions since they permanently accumulate surface charges and fields; moreover, ferroelectric surfaces show specific electrochemical reactivity as a function of the ferroelectric polarization that leads to a different composition of surface adsorbates as a function of ferroelectric polarization [1,2] as well as an irreversible imprint of the polarization on the native adsorbates layer [3]. Among surface electrochemical reactions, water splitting is naturally observed on FE oxide surfaces and hence hints at their application for water splitting. Moreover, the chemical reactivity of the FE surface and molecules present there seems to couple to internal FE polarization via many different mechanism. This feature opens new opportunities such as ferrocatalysis and the coupling of FE polarization to surface organic molecules.[4]

Here, I will present an extended view of the water splitting reactions (including oxygen and hydrogen evolution reactions) on ferroelectric surfaces as a function of polarization, obtained from the combination of near ambient pressure XPS analysis and Scanning Probe Microscopy techniques (essentially Piezoresponse Force Microscopy and Kelvin Probe Force Microscopy). We have studied surface electrochemical reactivity (and associated oxidation and reduction reactions) of ferroelectric thin films and single crystals and shown how the surface redox activity is coupled to ferroelectricity by several different factors. In this sense, the potential of ferroelectric materials for photocatalytic water splitting applications will be discussed.

References

[1] K. Cordero-Edwards, L. Rodríguez, A. Calo, M. J. Esplandiu, V. Peŕez-Dieste, C. Escudero, N. Domingo and A.Verdaguer, J. Phys. Chem. C, 120, 24048 (2016).

[2] N. Domingo, E. Pach, K. Cordero-Edwards, V. Pérez-Dieste, C. Escudero, A. Verdaguer. Phys. Chem.Chem.Phys, 21 (2019), 4920

[3] N.Domingo, I.Gaponenko, N.Stucki, K.Cordero-Edwards, V.Pérez-Dieste, C.Escudero, E.Pach, A.Verdaguer, P.Paruch, Nanoscale, 11 (2019) 17920

[4] I. Spasojevic, PhD Thesis, Universitat Autonoma de Barcelona, June 2022.