Evolution of Oxygen–Metal Electron Transfer and Metal Electronic States During Manganese Oxide Catalyzed Water Oxidation Revealed with In Situ Soft X-Ray Spectroscopy

Marc F. Tesch, Shannon A. Bonke, Travis E. Jones, Maryam N. Shaker, Jie Xiao, Katarzyna Skorupska, Rik Mom, Jens Melder, Philipp Kurz, Axel Knop-Gericke, Robert Schlögl, Rosalie K. Hocking, Alexandr N. Simonov

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16 Citations (Scopus)

Abstract

Manganese oxide (MnOx) electrocatalysts are examined herein by in situ soft X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) during the oxidation of water buffered by borate (pH 9.2) at potentials from 0.75 to 2.25 V vs. the reversible hydrogen electrode. Correlation of L-edge XAS data with previous mechanistic studies indicates MnIV is the highest oxidation state involved in the catalytic mechanism. MnOx is transformed into birnessite at 1.45 V and does not undergo further structural phase changes. At potentials beyond this transformation, RIXS spectra show progressive enhancement of charge transfer transitions from oxygen to manganese. Theoretical analysis of these data indicates increased hybridization of the Mn−O orbitals and withdrawal of electron density from the O ligand shell. In situ XAS experiments at the O K-edge provide complementary evidence for such a transition. This step is crucial for the formation of O2 from water.

Original languageEnglish
Pages (from-to)3426-3432
Number of pages7
JournalAngewandte Chemie - International Edition
Volume58
Issue number11
DOIs
Publication statusPublished - 1 Jan 2019

Keywords

  • in situ spectroscopy
  • manganese oxide
  • resonant inelastic X-ray scattering
  • soft X-ray absorption spectroscopy
  • water electrooxidation

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