Jinzhen Huang^1*, Camelia Nicoleta Borca^2*, Thomas Huthwelker^2*, Nur Sena Yüzbasi^3*, Thomas J. Schmidt^1,4*, Emiliana Fabbri^1*

1 Electrochemistry Laboratory, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland

2 Photon Science Division, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland

3 Laboratory for High Performance Ceramics, Empa - Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland

4 Institute for Physical Molecular Sciences, ETH Zürich, CH-8093 Zürich, Switzerland

* Corresponding authors emails: jinzhen.huang@psi.ch, camelia.borca@psi.ch, thomas.huthwelker@psi.ch, Sena.Yuezbasi@empa.ch, thomasjustus.schmidt@psi.ch, emiliana.fabbri@psi.ch

DOI10.24435/materialscloud:v8-hq [version v1]

Publication date: Oct 17, 2023

How to cite this record

Jinzhen Huang, Camelia Nicoleta Borca, Thomas Huthwelker, Nur Sena Yüzbasi, Thomas J. Schmidt, Emiliana Fabbri, Unveiling the pH-dependent structure-activity relationship of Co-based catalysts toward oxygen evolution reaction, Materials Cloud Archive 2023.158 (2023), doi: 10.24435/materialscloud:v8-hq.

Description

Co-based catalysts are promising candidates to replace the Ir/Ru-based oxides for the oxygen evolution reaction (OER) in an acidic environment. However, both the reaction mechanism and the active species in an acidic environment remain unclear. In this study, by combining surface-sensitive soft X-ray adsorption spectroscopy (sXAS) characterization with electrochemical analysis, we unveil the truly active Co species for acidic OER. Surfaces composed of only high-spin Co^II are found to be not active due to their unfavorable deprotonation to form Co^III-OH species. In contrast, we show that the presence of low-spin Co^III is essential to promote surface reconstruction and catalysis of OER. The correlation between OER activity and Co oxidation/spin state represents a breakthrough in the structure-activity relationship of Co-based catalysts for acidic OER, which interestingly does not hold in the alkaline and neutral environments. These findings not only help to design efficient acidic OER catalysts, but also deepen the understanding of the reaction mechanism.

Materials Cloud sections using this data

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File name	Size	Description
Raw data for CoIIinacid.xlsx MD5md5:d8c84be2ebf0373abae8d0e7c8864c9d	563.5 KiB	This file includes the raw data for the figures in the main test (Figures 1-4), including polarization curves, Tafel plots, Tafel slope and sXAS spectra, etc.

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External references

Keywords

acidic oxygen evolution structure-activity relationship cobalt based catalyst Co oxidation state spin state