The performance and stability of a direct methanol fuel cell (DMFC) with membrane electrode assemblies (MEA) using different Nafion® contents (30, 50 and 70 wt% or MEA30, MEA50 and MEA70, respectively) and graphitized carbon nanofiber (GNF) supported PtRu catalyst at the anode was investigated by a constant current measurement of 9 days (230 h) in a DMFC and characterization with various techniques before and after this measurement. Of the pristine MEAs, MEA50 reached the highest power and current densities. During the 9-day measurement at a constant current, the performance of MEA30 decreased the most (−124 μV h−1), while the MEA50 was almost stable (−11 μV h−1) and performance of MEA70 improved (+115 μV h−1). After the measurement, the MEA50 remained the best MEA in terms of performance. The optimum anode Nafion content for commercial Vulcan carbon black supported PtRu catalysts is between 20 and 40 wt%, so the GNF-supported catalyst requires more Nafion to reach its peak power. This difference is explained by the tubular geometry of the catalyst support, which requires more Nafion to form a penetrating proton conductive network than the spherical Vulcan. Mass transfer limitations are mitigated by the porous 3D structure of the GNF catalyst layer and possible changes in the compact Nafion filled catalyst layers during constant current production.
|Number of pages||10|
|Journal||International Journal of Hydrogen Energy|
|Publication status||Published - Dec 2012|
|MoE publication type||A1 Journal article-refereed|
- Anode structure, Carbon nanofiber, Direct methanol fuel cell, Durability, Ionomer content, Nafion