Carbon Corrosion in Proton-Exchange Membrane Fuel Cells: Effect of the Carbon Structure, the Degradation Protocol, and the Gas Atmosphere

Autor(es)

Castanheira, Luis ^{[1, 2]} ; Silva, Wanderson O. ^[3] ; Lima, Fabio H. B. ^[3] ; Crisci, Alexandre ^{[4, 5]} ; Dubau, Laetitia ^{[1, 2]} ; Maillard, Frederic ^{[1, 2]}

Afiliação do(s) autor(es)

^[1] Univ Grenoble Alpes, LEPMI, F-38000 Grenoble - France

^[2] CNRS, LEPMI, F-38000 Grenoble - France

^[3] Univ Sao Paulo, Inst Quim Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil

^[4] Univ Grenoble Alpes, SIMAP, F-38000 Grenoble - France

^[5] CNRS, SIMAP, F-38000 Grenoble - France

• Tipo de documento: Artigo Científico
• Fonte: ACS CATALYSIS; v. 5, n. 4, p. 2184-2194, APR 2015.
• Citações Web of Science: 103

Resumo

The impact of the carbon structure, the aging protocol, and the gas atmosphere on the degradation of Pt/C electrocatalysts were studied by electrochemical and spectroscopic methods. Pt nanocrystallites loaded onto high-surface area carbon (HSAC), Vulcan XC72, or reinforced-graphite (RG) with identical Pt weight fraction (40 wt %) were submitted to two accelerated stress test (AST) protocols from the Fuel Cell Commercialization Conference of Japan (FCCJ) mimicking load-cycling or start-up/shutdown events in a proton-exchange membrane fuel cell (PEMFC). The load-cycling protocol essentially caused dissolution/redeposition and migration/aggregation/coalescence of the Pt nanocrystallites but led to similar electrochemically active surface area (ECSA) losses for the three Pt/C electrocatalysts. This suggests that the nature of the carbon support plays a minor role in the potential range 0.60 < E < 1.0 V versus RHE. In contrast, the carbon support was strongly corroded under the start-up/shutdown protocol (1.0 < E < 1.5 V versus RHE), resulting in pronounced detachment of the Pt nanocrystallites and massive ECSA losses. Raman spectroscopy and differential electrochemical mass spectrometry were used to shed light on the underlying corrosion mechanisms of structurally ordered and disordered carbon supports in this potential region. Although for Pt/HSAC the start-up/shutdown protocol resulted into preferential oxidation of the more disorganized domains of the carbon support, new structural defects were generated at quasi-graphitic crystallites for Pt/RG. Pt/Vulcan represented an intermediate case. Finally, we show that oxygen affects the surface chemistry of the carbon supports but negligibly influences the ECSA losses for both aging protocols. (AU)

• Processo FAPESP: 11/50727-9 - Desenvolvimento de sistemas para produção de hidrogênio e para geração e utilização de energia eletro-química
• Beneficiário: Ernesto Rafael Gonzalez
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 13/16930-7 - Eletrocatálise V: processos eletrocatalíticos de interconversão entre as energias química e elétrica
• Beneficiário: Edson Antonio Ticianelli
• Modalidade de apoio: Auxílio à Pesquisa - Temático