1 Department of Physics, Chemistry and Pharmacy, Faculty of Science, SDU2 Institute of Chemical Engineering, Biotechnology and Environmental Technology, Faculty of Engineering, SDU3 Faculty of Engineering, SDU4 Institute for material s and surface technology, University of Applied Sciences, Kiel, Germany5 IRD Fúel Cells A/S6 Institute of Chemical Engineering, Biotechnology and Environmental Technology, Faculty of Engineering, SDU
Proton Exchange Membrane (PEM) fuel cell electrodes with different ionomer contents were studied with various microscopic techniques. The morphology and surface potential were examined by Atomic Force Microscopy (AFM) and Kelvin Probe Microscopy (KPM), respectively. The particulate nature of the electrode was well displayed in the topography and phase images. The particle and pore size (Z) distributions showed the most frequent values at 30-40 nm and 20-30 nm, respectively. The particle size corresponds to the size of the carbon support for the platinum catalyst. Catalyst agglomeration was observed in high ionomer content electrodes. The surface potential images showed distinct difference to the topography images. The overall grain size was seen to increase, the pore volume to decrease, the surface roughness to decrease, and the surface potential variation to increase with the increase of ionomer content in the catalyst layer. Transmission electron microscopy (TEM) was carried out on selective electrodes to provide additional information and confirmed with the AFM results. Cyclic voltammetry (CV) showed that the electrode containing 30 wt.% ionomer has maximum catalyst utilization.
Applied Physics A: Materials Science and Processing, 2009, Vol 96, Issue 3, p. 581-589