Casey E. Beall¹, Emiliana Fabbri^1*, Adam H. Clark¹, Vivian Meier^1,2, Nur Sena Yüzbasi³, Benjamin H. Sjølin⁴, Ivano E. Castelli^4*, Dino Aegerter¹, Thomas Graule³, Thomas J. Schmidt^1,2

1 Paul Scherrer Institute (PSI), 5232 Villigen PSI, Switzerland

2 Institute for Physical Molecular Science, ETH Zürich, 8093 Zürich, Switzerland

3 Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland

4 Department of Energy Conversion and Storage, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark

* Corresponding authors emails: emiliana.fabbri@psi.ch, ivca@dtu.dk

DOI10.24435/materialscloud:bk-y8 [version v1]

Publication date: Jul 28, 2023

How to cite this record

Casey E. Beall, Emiliana Fabbri, Adam H. Clark, Vivian Meier, Nur Sena Yüzbasi, Benjamin H. Sjølin, Ivano E. Castelli, Dino Aegerter, Thomas Graule, Thomas J. Schmidt, Time-resolved oxidation state changes are key to elucidating the bifunctionality of perovskite catalysts for oxygen evolution and reduction, Materials Cloud Archive 2023.121 (2023), doi: 10.24435/materialscloud:bk-y8.

Description

In a unified regenerative fuel cell (URFC) or reversible fuel cell the oxygen bifunctional catalyst must switch reversibly between the oxygen reduction reaction (ORR), fuel cell mode, and the oxygen evolution reaction (OER), electrolyzer mode. However, it is often unclear what effect alternating between ORR and OER has on the electrochemical behavior and physiochemical properties of the catalyst. Herein, operando X-ray absorption spectroscopy (XAS) is utilized to monitor the continuous and dynamic evolution of the Co, Mn, and Fe oxidation states of perovskite catalysts Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) and La0.4Sr0.6MnO3-δ (LSM), while the potential is oscillated between reducing and oxidizing potentials with cyclic voltammetry. The results reveal the importance of investigating bifunctional catalysts by alternating between fuel cell and electrolyzer operation and highlight the limitations and challenges of bifunctional catalysts. It is shown that the requirements for ORR and OER performance are divergent and that the oxidative potentials of OER are detrimental to ORR activity. These findings are used to give guidelines for future bifunctional catalyst design. Additionally, it is demonstrated how sunlight can be used to reactivate the ORR activity of LSM after rigorous cycling.

Materials Cloud sections using this data

Files

File name	Size	Description
Conductivity.zip MD5md5:68316f601785f71b80fce7ebad01ecf0	2.7 KiB	Conductivity Measurements
Electrochemistry.zip MD5md5:3e392eaeef151a05e3c6c1e0b7175f22	1.8 MiB	Electrochemistry
XRD.zip MD5md5:96e08efec8a5f6e63424bb1433b9cf92	20.8 KiB	XRD
XAS.zip MD5md5:5e5487730db91fcac55724a983443a02	909.2 MiB	XAS
README.txt MD5md5:c5c73fd261d719dc9e670e5c7ab348f0	485 Bytes	Read me text file

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External references

Keywords

ORR OER alkaline Experimental SNSF