Understanding a Degradation Mechanism of Direct Methanol Fuel Cell Using TOF-SIMS and XPS

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• 作者：Youngsu Chung ; Chanho Pak ; Gyeong-Su Park ; Woo Sung Jeon ; Ji-Rae Kim ; Yoonhoi Lee ; Hyuk Chang ; Doyoung Seung
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：January 10, 2008
• 年：2008
• 卷：112
• 期：1
• 页码：313 - 318
• 全文大小：549K
• 年卷期：v.112,no.1(January 10, 2008)
• ISSN：1932-7455

文摘

The catalyst layers, which were obtained from the aged membrane electrode assemblies (MEAs) showingperformance loss, 17%, 37%, 45% as compared with that from the pristine MEA were investigated usingX-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectroscopy (TOF-SIMS) tounderstand the degradation mechanism of single-cell performance in direct methanol fuel cell. The metalliccomponents in the PtRu anode catalyst layer was decreased significantly with the performance drop revealedfrom the change of the valance bands. It has been found that ruthenium and platinum were driven to thecathode by the gradient of electric field during the durability test. From the mass-resolved imaging techniqueof TOF-SIMS combined with a peel-off method, it was indicated that the traveled ruthenium from anode tocathode was not uniformly distributed within the cathode catalyst layer, but more accumulated at the surfaceof the catalyst layer, that is, the interface with the gas diffusion layer. XPS and TOF-SIMS results suggestedthat the ruthenium ions are electro-deposited to RuO_x rather than metallic Ru, which seems to more closelycorrelate with the degradation of performance.