# In-situ structure and catalytic mechanism of NiFe and CoFe layered double hydroxides during oxygen evolution

“In-situ structure and catalytic mechanism of NiFe and CoFe layered double hydroxides during oxygen evolution” (2020), by Fabio Dionigi et al. Energy research paper. Original abstract below, unchanged. A free PDF is available.

- Authors: Fabio Dionigi, Zhenhua Zeng, Ilya V. Sinev, Thomas Merzdorf, Siddharth Deshpande, Miguel Bernal, Sebastian Kunze, Ioannis Zegkinoglou, Hannes Sarodnik, Dingxin Fan et al.
- Published: May 20, 2020
- Field: Energy
- DOI: https://doi.org/10.1038/s41467-020-16237-1
- Free PDF: https://www.nature.com/articles/s41467-020-16237-1.pdf

## Abstract

NiFe and CoFe (MFe) layered double hydroxides (LDHs) are among the most active electrocatalysts for the alkaline oxygen evolution reaction (OER). Herein, we combine electrochemical measurements, operando X-ray scattering and absorption spectroscopy, and density functional theory (DFT) calculations to elucidate the catalytically active phase, reaction center and the OER mechanism. We provide the first direct atomic-scale evidence that, under applied anodic potentials, MFe LDHs oxidize from as-prepared α-phases to activated γ-phases. The OER-active γ-phases are characterized by about 8% contraction of the lattice spacing and switching of the intercalated ions. DFT calculations reveal that the OER proceeds via a Mars van Krevelen mechanism. The flexible electronic structure of the surface Fe sites, and their synergy with nearest-neighbor M sites through formation of O-bridged Fe-M reaction centers, stabilize OER intermediates that are unfavorable on pure M-M centers and single Fe sites, fundamentally accounting for the high catalytic activity of MFe LDHs.

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