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Covalency competition dominates the water oxidation structure–activity relationship on spinel oxides

An Author Correction to this article was published on 04 November 2020

This article has been updated


Spinel oxides have attracted growing interest over the years for catalysing the oxygen evolution reaction (OER) due to their efficiency and cost-effectiveness, but fundamental understanding of their structure–property relationships remains elusive. Here we demonstrate that the OER activity on spinel oxides is intrinsically dominated by the covalency competition between tetrahedral and octahedral sites. The competition fabricates an asymmetric MT−O−MO backbone where the bond with weaker metal–oxygen covalency determines the exposure of cation sites and therefore the activity. Driven by this finding, a dataset with more than 300 spinel oxides is computed and used to train a machine-learning model for screening the covalency competition in spinel oxides, with a mean absolute error of 0.05 eV. [Mn]T[Al0.5Mn1.5]OO4 is predicted to be a highly active OER catalyst and subsequent experimental results confirm its superior activity. This work sets mechanistic principles of spinel oxides for water oxidation, which may be extendable to other applications.

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Fig. 1: Patterning OER mechanisms on spinel oxides based on the DOS.
Fig. 2: Relationship between OER activity and the covalency competition in spinel oxides.
Fig. 3: Machine-learning approach for fast screening the covalency competition in spinel oxides.
Fig. 4: Experimental analysis of the synthesized spinel Al0.5Mn2.5O4.

Data availability

The data supporting the findings of this study are available within the article and its Supplementary Information. Additional data are available from the corresponding authors on reasonable request.

Code availability

The machine-learning codes for making the covalency competition prediction are available at

Change history

  • 04 November 2020

    An amendment to this paper has been published and can be accessed via a link at the top of the paper.


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This work was supported by Singapore Ministry of Education Tier 2 Grant (MOE-2018-T2-2-027) and the Singapore National Research Foundation under its Campus for Research Excellence And Technological Enterprise (CREATE) programme. We thank the Facility for Analysis, Characterization, Testing, and Simulation (FACTS) in Nanyang Technological University. This research used resources of the National Synchrotron Light Source II, a US Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under contract no. DE-SC0012704. We also appreciate the XAS measurements from SSLS, soft X-ray and ultraviolet beamline. Y.S. and Z.X. thank A. Lapkin (University of Cambridge) for helpful discussion on machine-learning concepts and thank L. Zeng (Southern University of Science and Technology) for helpful discussion on catalyst performance. H.Z. gives thanks for the support from ITC via the Hong Kong Branch of National Precious Metals Material (NPMM) Engineering Research Center, and the start-up grant (project no. 9380100) and grants (project no. 9610478 and 1886921) in City University of Hong Kong.

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Authors and Affiliations



Z.J.X. and Y.S. proposed the research. Y.S., H.L. and Z.J.X. designed the experiments. Y.S. conducted DFT modelling and simulations. H.L. established the mathematical approach. H.L., J.W., S.S., B.C. and S.J.H.O. carried out the experiments. S.X., C.D., Y.D., J.W., J.O.W., Y.S. and H.L. conducted XAS characterizations. Y.S. wrote the manuscript. H.L., S.X., Y.D., M.B.H.B., S.L., H.Z. and Z.J.X. performed the analysis and revised the manuscript.

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Correspondence to Zhichuan J. Xu.

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Supplementary information

Supplementary Information

Supplementary Tables 1–11 and Figs. 1–12.

Supplementary Data 1

Atomic coordinates of the calculated bulk spinels.

Supplementary Data 2

Atomic coordinates of the OER intermediates.

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Sun, Y., Liao, H., Wang, J. et al. Covalency competition dominates the water oxidation structure–activity relationship on spinel oxides. Nat Catal 3, 554–563 (2020).

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