Carbon Corrosion in Proton-Exchange Membrane Fuel Cells: Spectrometric Evidence for Pt-Catalysed Decarboxylation at Anode-Relevant Potentials |
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Authors: | Dr Frédéric Maillard Dr Wanderson O Silva Dr Luis Castanheira Dr Laetitia Dubau Prof?Dr Fabio H B Lima |
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Institution: | 1. Univ. Grenoble Alpes, Univ. Savoie Mont Blanc CNRS, Grenoble INP, LEPMI, 38000 Grenoble, France;2. Instituto de Química de São Carlos, Universidade de São Paulo CEP, 13560-970 CP 780?São Carlos, SP, Brazil |
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Abstract: | The carbon oxidation reaction (COR) is a critical issue in proton-exchange membrane fuel cells (PEMFCs), as carbon in various forms is the most used electrocatalyst support material. The COR is thermodynamically possible above the C/CO2 standard potential, but its rate becomes significantly important only at high overpotential (e. g. PEMFC cathode potential). Herein, using on-line differential electrochemical mass spectrometry, we show that oxygen-containing carbon surface groups present on high-surface aera carbon, Vulcan XC72 or reinforced graphite are oxidized at PEMFC anode-relevant potential (E=0.1 V vs. the reversible hydrogen electrode, RHE), but not at E=0.4 V vs. RHE. We rationalized our findings by considering a Pt-catalysed decarboxylation mechanism in which Pt nanoparticles provide adsorbed hydrogen species to the oxygen-containing carbon surface groups, eventually leading to evolution of carbon dioxide and carbon monoxide. These results shed fundamental light on an unexpected degradation mechanism and facilitate the understanding of the long-term stability of PEMFC anode nanocatalysts. |
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Keywords: | anode carbon corrosion decarboxylation electrocatalysis proton-exchange membrane fuel cells |
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