Elucidating the Complex Oxidation Behavior of Aqueous H3PO3 on Pt Electrodes via In Situ Tender X-ray Absorption Near-Edge Structure Spectroscopy at the P K-Edge

Wibowo RE, Garcia-Diez R, Bystron T, van der Merwe M, Prokop M, Arce MD, Efimenko A, Steigert A, Bernauer M, Wilks RG, Bouzek K, Bär M (2024)

Publication Type: Journal article

Publication year: 2024

Journal

Journal of the American Chemical Society American Chemical Society

Book Volume: 146

Pages Range: 7386-7399

Journal Issue: 11

DOI: 10.1021/jacs.3c12381

Abstract

In situ tender X-ray absorption near-edge structure (XANES) spectroscopy at the P K-edge was utilized to investigate the oxidation mechanism of aqueous H3PO3 on Pt electrodes under various conditions relevant to high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC) applications. XANES and electrochemical analysis were conducted under different tender X-ray irradiation doses, revealing that intense radiation induces the oxidation of aqueous H3PO3 via H2O yielding H3PO4 and H2. A broadly applicable experimental procedure was successfully developed to suppress these undesirable radiation-induced effects, enabling a more accurate determination of the aqueous H3PO3 oxidation mechanism. In situ XANES studies of aqueous 5 mol dm^-3 H3PO3 on electrodes with varying Pt availability and surface roughness reveal that Pt catalyzes the oxidation of aqueous H3PO3 to H3PO4. This oxidation is enhanced upon applying a positive potential to the Pt electrode or raising the electrolyte temperature, the latter being corroborated by complementary ion-exchange chromatography measurements. Notably, all of these oxidation processes involve reactions with H2O, as further supported by XANES measurements of aqueous H3PO3 of different concentrations, showing a more pronounced oxidation in electrolytes with a higher H2O content. The significant role of water in the oxidation of H3PO3 to H3PO4 supports the reaction mechanisms proposed for various chemical processes observed in this work and provides valuable insights into potential strategies to mitigate Pt catalyst poisoning by H3PO3 during HT-PEMFC operation.

Authors with CRIS profile

Marcus Bär

Involved external institutions

Helmholtz-Zentrum Berlin für Materialien und Energie (HZB)

Germany (DE) University of Chemistry and Technology (UCT) / Vysoká škola chemicko-technologická (VŠCHT)

Czech Republic (CZ)

How to cite

APA:

Wibowo, R.E., Garcia-Diez, R., Bystron, T., van der Merwe, M., Prokop, M., Arce, M.D.,... Bär, M. (2024). Elucidating the Complex Oxidation Behavior of Aqueous H3PO3 on Pt Electrodes via In Situ Tender X-ray Absorption Near-Edge Structure Spectroscopy at the P K-Edge. Journal of the American Chemical Society, 146(11), 7386-7399. https://dx.doi.org/10.1021/jacs.3c12381

MLA:

Wibowo, Romualdus Enggar, et al. "Elucidating the Complex Oxidation Behavior of Aqueous H3PO3 on Pt Electrodes via In Situ Tender X-ray Absorption Near-Edge Structure Spectroscopy at the P K-Edge." Journal of the American Chemical Society 146.11 (2024): 7386-7399.

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