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Following Adsorbed Intermediates on a Platinum Gas Diffusion Electrode in H₃PO₃-Containing Electrolytes Using In Situ X-ray Absorption Spectroscopy

Title data

Ferreira Gomes Lobo, Bruna ; Prokop, Martin ; Bystron, Tomas ; Loukrakpam, Rameshwori ; Melke, Julia ; Lobo, Carlos M. S. ; Fink, Michael ; Zhu, Mengshu ; Voloshina, Elena ; Kutter, Maximilian ; Hoffmann, Hendrik ; Yusenko, Kirill V. ; Buzanich, Ana Guilherme ; Röder, Bettina ; Bouzek, Karel ; Paulus, Beate ; Roth, Christina:
Following Adsorbed Intermediates on a Platinum Gas Diffusion Electrode in H₃PO₃-Containing Electrolytes Using In Situ X-ray Absorption Spectroscopy.
In: ACS Catalysis. Vol. 12 (2022) Issue 18 . - pp. 11472-11484.
ISSN 2155-5435
DOI: https://doi.org/10.1021/acscatal.2c02630

Abstract in another language

One of the challenges of high-temperature polymer electrolyte membrane fuel cells is the poisoning of the Pt catalyst with H3PO4. H3PO4 is imbibed into the routinely used polybenzimidazole-based membranes, which facilitate proton conductivity in the temperature range of 120–200 °C. However, when leached out of the membrane by water produced during operation, H3PO4 adsorbs on the Pt catalyst surface, blocking the active sites and hindering the oxygen reduction reaction (ORR). The reduction of H3PO4 to H3PO3, which occurs at the anode due to a combination of a low potential and the presence of gaseous H2, has been investigated as an additional important contributing factor to the observed poisoning effect. H3PO3 has an affinity toward adsorption on Pt surfaces even greater than that of H2PO4–. In this work, we investigated the poisoning effect of both H3PO3 and H3PO4 using a half-cell setup with a gas diffusion electrode under ambient conditions. By means of in situ X-ray absorption spectroscopy, it was possible to follow the signature of different species adsorbed on the Pt nanoparticle catalyst (H, O, H2PO4–, and H3PO3) at different potentials under ORR conditions in various electrolytes (HClO4, H3PO4, and H3PO3). It was found that H3PO3 adsorbs in a pyramidal configuration P(OH)3 through a Pt–P bond. The competition between H3PO4 and H3PO3 adsorption was studied, which should allow for a better understanding of the catalyst poisoning mechanism and thus assist in the development of strategies to mitigate this phenomenon in the future by minimizing H3PO3 generation by, for example, improved catalyst design or adapted operation conditions or changes in the electrolyte composition.

Further data

Item Type: Article in a journal
Refereed: Yes
Institutions of the University: Faculties > Faculty of Engineering Science > Chair Electrochemical Process Engineering > Chair Electrochemical Process Engineering - Univ.-Prof. Dr. Christina Roth
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 540 Chemistry
600 Technology, medicine, applied sciences > 620 Engineering
Date Deposited: 20 Sep 2022 07:18
Last Modified: 20 Sep 2022 07:18
URI: https://eref.uni-bayreuth.de/id/eprint/71903