IMF 2023

Ferroelectric-ionic catalysis in BaTiO3/CeO2-δ heterostructures

Milica Vasiljevic 1 Francesco Chiabrera 1,2 Shinhee Yun 1 Victor Burrato Tinti 1 Nini Pryds 1 Vincenzo Esposito 1
1Department of Energy Conversion and Storage, Technical University of Denmark, Copenhagen, Denmark
2Department of Advanced Materials for Energy, Catalonia Institute for Energy Research (IREC), Barcelona, Spain

Safely producing renewable fuels is one of the most important tasks among the scientific community nowadays. Since the discovery that piezoelectric potential can dramatically affect the difference of electrochemical potentials between charges on the surface and its surroundings [1], the possibility of using complex oxides as piezoelectric-based catalysts raised a lot of attention. Piezocatalysis is an ability of a piezoelectric material that converts mechanical stresses into charges to trigger redox reactions [2]. The potential induced by strain can generate a giant electric field, which affects charge energy shifting or transferring electrons and holes. A prerequisite for a high electrochemical activity is a low electrical conductivity and high piezoelectric coefficient, considering that electrical permittivity must be optimized to balance piezoelectric and capacitive effects [3].

Here, we studied heterostructures consisting of CeO2 and BaTiO3 to understand the possibility of optimizing the electrical permittivity of ceria by controlling the properties of the layers. Ceria has a high electrochemical activity because of its high concentration of electronic defects, i.e. oxygen vacancies and small polarons [4]. We performed PLD growth of BaTiO3/ CeO2-δ heterostructures to investigate the influence of BaTiO3 ingrowth polarization on defects (holes) concentration in CeO2-δ. The direction of the polarization of the BaTiO3 thin films was controlled by the choice of bottom electrode [5]. In this way, by adding SrRuO3 we obtained positive polarization at the ceria`s surface, i.e. high oxygen defects, while negative polarization was achieved without SrRuO3 by optimizing the PLD growth parameters on Nb:SrTiO3 substrate. The possibility of tuning the defect’s concentration of CeO2-δ thin films offers a promising way to tune its catalytic activity for efficient fuel production.

1. Hamann T. Wet et al. J. Am. Chem. Soc. 127, 7815–7824 (2005).

2. Starr M. B. et al. Angew. Chem. Int. 51, 5962–5966 (2012).

3. Starr M. B. & Xudong W. Sci. Rep.3, 2160 (2013).

4. Pryds N. & Esposito V. J. Electroceram., 38 (1), 1-23 (2012).
5. Highland M. J. et al. Phys. Rev. Lett. 107, 187602 (2011).





IMF 2023




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