Anodic and Cathodic Platinum Dissolution Processes Involve Different Oxide Species |
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| Authors: | Timo Fuchs Valentín Briega-Martos Jakub Drnec Natalie Stubb Isaac Martens Federico Calle-Vallejo Prof David A Harrington Serhiy Cherevko Prof Olaf M Magnussen |
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| Institution: | 1. Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Olshausenstr. 40, 24098 Kiel, Germany;2. Forschungszentrum Jülich GmbH, Helmholtz-Institute Erlangen-Nürnberg for Renewable Energy (IEK-11), Cauerstr. 1, 91058 Erlangen, Germany;3. Experimental division, European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France;4. Chemistry Department, University of Victoria, Victoria, British Columbia, V8W 2Y2 Canada;5. Nano-Bio Spectroscopy Group and European Theoretical Spectroscopy Facility (ETSF), Department of Advanced Materials and Polymers: Physics, Chemistry and Technology, University of the Basque Country UPV/EHU, Av. Tolosa 72, 20018 San Sebastián, Spain |
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| Abstract: | The degradation of Pt-containing oxygen reduction catalysts for fuel cell applications is strongly linked to the electrochemical surface oxidation and reduction of Pt. Here, we study the surface restructuring and Pt dissolution mechanisms during oxidation/reduction for the case of Pt(100) in 0.1 M HClO4 by combining operando high-energy surface X-ray diffraction, online mass spectrometry, and density functional theory. Our atomic-scale structural studies reveal that anodic dissolution, detected during oxidation, and cathodic dissolution, observed during the subsequent reduction, are linked to two different oxide phases. Anodic dissolution occurs predominantly during nucleation and growth of the first, stripe-like oxide. Cathodic dissolution is linked to a second, amorphous Pt oxide phase that resembles bulk PtO2 and starts to grow when the coverage of the stripe-like oxide saturates. In addition, we find the amount of surface restructuring after an oxidation/reduction cycle to be potential-independent after the stripe-like oxide has reached its saturation coverage. |
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| Keywords: | catalyst degradation density functional calculations online mass spectrometry platinum oxidation X-ray diffraction |
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