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Understanding the inter-site distance effect in single-atom catalysts for oxygen electroreduction

Abstract

Regulating the site density of single-atom catalysts (SACs) promotes the potential to remarkably improve the performance of electrocatalysis, such as the oxygen reduction reaction (ORR). However, the catalytic behaviour governed by individual and interacting sites is particularly elusive and has yet to be understood. Here we demonstrate the origin of the enhancement of the ORR activity of isolated Fe–N4 SACs over inter-site distances down to the subnanometre level. Strong interactions between adjacent Fe–N4 moieties alter the electronic structure when the inter-site distance is less than about 1.2 nm, resulting in increased intrinsic ORR activity. The marked improvement in site performance continues until neighbouring Fe atoms approach as close as about 0.7 nm, below which the intrinsic activity is slightly diminished. The present study highlights the significance of identifying the fundamental mechanism of the inter-site distance effect in Fe–N4 catalysts for the ORR, which may promote the full potential of densely populated SACs.

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Fig. 1: Characterizations of Fe–N4 SACs with different dsite values.
Fig. 2: Correlation of Fe contents and site densities with different dsite values.
Fig. 3: Apparent ORR activity.
Fig. 4: The dsite-dependent active site.
Fig. 5: Identification of the dsite-dependent inter-site interaction.

Data availability

All data that support the findings in this paper are available within the article and its Supplementary Information or from the corresponding authors on reasonable request.

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Acknowledgements

G.Y. acknowledges the funding support from the US Department of Energy, Office of Science, Basic Energy Sciences under Award DE-SC0019019, the Welch Foundation Award F-1861 and the Camille Dreyfus Teacher-Scholar Award. We sincerely thank A.J. Bard and his group for the support and thoughtful discussion on SECM.

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Contributions

G.Y. conceived and directed the project. Z.J. designed experiments, performed SI–SECM and simulations, and wrote the paper. P.L. conducted the synthesis of catalysts and electrochemical experiments. Y.M. and D.X. supported the characterizations and analysis. P.L. and Z.F. edited the manuscript. All authors discussed and revised the manuscript.

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Correspondence to Dan Xiao or Guihua Yu.

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The authors declare no competing interests.

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Peer review information Nature Catalysis thanks Hyun S. Park, Samira Siahrostami and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Information

Supplementary Figs. 1–24, Tables 1–13, Notes 1–11, Methods and References.

Supplementary Data 1

Atomic coordinates.

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Jin, Z., Li, P., Meng, Y. et al. Understanding the inter-site distance effect in single-atom catalysts for oxygen electroreduction. Nat Catal 4, 615–622 (2021). https://doi.org/10.1038/s41929-021-00650-w

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  • DOI: https://doi.org/10.1038/s41929-021-00650-w

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