The main probem for further progression of proton exchange membrane fuel cells (PEMFC) is the oxygen reduction reaction (ORR). Studying of catalysts for optimization of ORR is therefore an important part of new catalysts development for PEMFCs. The current methods for studying of ORR are thin film rotating disk electrode (TF-RDE) setups, where small ammounts of catalysts at low current densities are needed, and membrane electrode assembly (MEA) for tests under realistic contidions. However, if a catalyst shows good properties in TF-RDE it does not guarantee a good MEA performance. Recently there has been an emergance of a new electrochemical tool, a gas diffusion electrode (GDE), that retains the simplicity and low catalyst amount, and at the same time enables characterization under high current densities. This provides for a faster and more reliable ORR characterization. In this work, I established a novel GDE system and methods for ORR catalysts characterization. Furthermore, I also inspected the effect of ionomer to carbon ratio (I/C), and the influence of catalyst layer loading.
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