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Published March 11, 2026 | Version Supplemental material
Journal Article Open

In Situ Analysis of Manganese Antimonate Oxygen Evolution Electrocatalysts via Ambient Pressure X-ray Photoelectron Spectroscopy

Creators

  • 1. ROR icon California Institute of Technology
  • 2. ROR icon Northwestern University
  • 3. California Catalysts
  • 4. ROR icon Stanford University

Abstract

Manganese antimonates are earth-abundant potential alternatives to precious metal catalysts for the oxygen-evolution reaction (OER). Herein, X-ray photoelectron spectroscopy was used to determine the surface chemistry of a manganese antimonate catalyst for the OER under ultrahigh vacuum, ambient pressure, and in situ reaction conditions. Ex situ and in situ analyses revealed the oxidation states of surficial species as a function of material stoichiometry, water content, and applied potential. In situ XPS measurements in 1.0 M KOH(aq) indicated that relative to the rest state, the surface Mn(III) partially oxidized while effecting the OER, with approximately 15% of the Mn signal attributable to Mn(IV) and the remainder attributable to Mn(III).

Copyright and License (English)

© 2026 American Chemical Society.

Acknowledgement (English)

This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award Number DE-FG02-03-ER15483. This research used resources of the Advanced Light Source, which is a DOE Office of Science User Facility under contract no. DE-AC02-05CH11231, utilizing Endstation 9.3.1.1 Tender X-ray AP-XPS. The authors graciously acknowledge Rebecca Hamlyn, Haoyi Li, Oliver Quinn Carvalho, and especially Ethan Crumlin for their assistance and advice during data collection at the Advanced Light Source. Research was in part carried out at the Molecular Materials Research Center in the Beckman Institute of the California Institute of Technology.

Conflict of Interest (English)

The authors declare the following competing financial interest(s): N.L. is a scientific founder of and consultant to California Catalysis, a company developing catalysts and electrolyzers for the production of hydrogen.

Supplemental Material

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsami.5c23862.

  • XRD compared to computed reflection patterns from literature database, cyclic voltammograms of catalysts studied in 1.0 M KOH, XP spectra of Mn2O3 standard, discussion of vapor impact on surface chemistry with associated XP spectra and data, SEM of the beam-damaged surface, XPS and electrochemical data supporting potential control, discussion of Sb 3d/O 1s signal in AP-XPS conditions with associated spectra, raw XP spectra for in situ XPS, and statistical analysis of fits (PDF)

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Additional details

Identifiers

PMID
41733173

Funding

Office of Basic Energy Sciences
DE-FG02-03-ER15483

Dates

Available
2026-02-24
Published online

Caltech Custom Metadata

Caltech groups
Division of Chemistry and Chemical Engineering (CCE)
Publication Status
Published