It is well known that the electrode structure of a PEMFC has a huge influence on the water management and thereby on the cell performance. In this work, two MEAs – one prepared by an airbrushing technique and the other by a novel fast spray coating technique (multilayered MEA) – were analysed with respect to porosity, pore size distribution, tortuosity and their electrochemical performance. FIB nanotomography with following 3D reconstruction, SEM investigation on ultramicrotomic thin‐sections, and single cell tests were performed on these MEAs. The results show a higher porosity and lower pore size for the multilayered MEA. The multilayered MEA reaches a Pt utilisation of 1,962 mW mg–1 and a peak power density of 210 mW cm–2, whereas the airbrushed MEA only provides a Pt utilisation of 879 mW mg–1 and a peak power density of 218 mW cm–2. The Pt utilisation calculations showed in combination with the structural characterisations that a homogeneous pore structure and Pt distribution provide an advantage with regard to performance and efficiency of the PEMFC. Furthermore, the multilayered MEA may offer an advantage over the airbrushed MEA in its long term stability, which was observed in preliminary tests.
Membrane electrode assemblies (MEA) for fuel cells require optimization of their nanoscale organization to reach performance parameters, which include enhanced power density, increased catalyst utilization and reduced cost. We applied sprayed layer-by-layer assembly to produce a high activity MEA for H(2)/O(2) fuel cells from polyaniline fibers (PANI-F). This technique produces "fast-prepared" membranes with nanoscale structure, which allows to adequately address specific tuning of their porosity, platinum loading, electronic conductivity, and proton conductivity. Pt nanoparticles were attached to the PANI-F in a reaction of selective heterogeneous nucleation. After functionalization, Pt/PANI-F were assembled with Nafion. Microscopic investigation revealed that functionalized polyaniline fibers formed a highly porous yet tight network of interpenetrating conductors connected to the catalytic Pt particles. The Pt/PANI-F LBL ultrathin MEA demonstrated a power densitiy of 63 mW cm(-2) and yielded a Pt utilization of 437.5 W g(-1) Pt which is comparable to the traditional fuel cell using carbon black as Pt support. Moreover, the amount of Pt used in this work is almost 2 times lower than for usual carbon-supported Pt catalysts.
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