ACS Appl Mater Interfaces
Leiden Institute of Chemistry, Leiden University, PO Box 9502, Leiden 2300 RA, The Netherlands.
Published: August 2022
Potential spikes during the start-up and shutdown of fuel cells are a major cause of platinum electrocatalyst degradation, which limits the lifetime of the device. The electrochemical oxidation of platinum (Pt) that occurs on the cathode during the potential spikes plays a key role in this degradation process. However, the composition of the oxide species formed as well as their role in catalyst dissolution remains unclear. In this study, we employ a special arrangement of XPS (X-ray photoelectron spectroscopy), in which the platinum electrocatalyst is covered by a graphene spectroscopy window, making the in situ examination of the oxidation/reduction reaction under wet conditions possible. We use this assembly to investigate the change in the oxidation states of Pt within the potential window relevant to fuel cell operation. We show that above 1.1 V (potential vs reversible hydrogen electrode), a mixed Pt/Pt/Pt surface oxide is formed, with an average oxidation state that gradually increases as the potential is increased. By comparing a model based on the XPS data to the oxidation charge measured during potential spikes, we show that our description of Pt oxidation is also valid during the transient conditions of fuel cell start-up and shutdown. This is due to the rapid Pt oxidation kinetics during the pulses. As a result of the irreversibility of Pt oxidation, some remnants of oxidized Pt remain at typical fuel cell operating potentials after a pulse.
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http://dx.doi.org/10.1021/acsami.2c09249 | DOI Listing |
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Centre for Nano and Soft Matter Sciences (CeNS), Shivanapura, Bengaluru 562162, India.
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Interdisciplinary Graduate Program in Materials Science, Vanderbilt University, Nashville, Tennessee 37235, United States.
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View Article and Find Full Text PDFInorg Chem
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Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0021, Japan.
Electrochemical devices that can operate at temperatures of 200-300 °C are expected to become the next-generation energy conversion devices in fuel cells and electrosynthesis, which are important for achieving carbon neutrality. Proton conductors based on phosphate glasses are being developed as candidate materials for such devices. We recently developed a glass proton conductor by using silicophosphoric acid based on the idea of solidifying phosphoric acid with silicon as a cross-linking glass framework.
View Article and Find Full Text PDFSmall
January 2025
School of Materials Science and Engineering, Tianjin Key Laboratory of Composite and Functional Materials Key Laboratory of Advanced Ceramics and Machining Technology (Ministry of Education), Tianjin University, Tianjin, 300072, China.
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Department of Clinical Pharmacy, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310003, China; Zhejiang Provincial Key Laboratory for Drug Evaluation and Clinical Research, Hangzhou, 310003, China. Electronic address:
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