When no hydrogen is able to reach the Pt/C catalyst in the anode of an operating Proton-Exchange-Membrane Fuel Cell (PEMFC), the potentials of the cathode and anode will be reversed. During this fuel cell reversal, the potential of the anode rises and the Oxygen Evolution Reactio
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When no hydrogen is able to reach the Pt/C catalyst in the anode of an operating Proton-Exchange-Membrane Fuel Cell (PEMFC), the potentials of the cathode and anode will be reversed. During this fuel cell reversal, the potential of the anode rises and the Oxygen Evolution Reaction (OER) and Carbon Oxidation Reaction (COR) will occur. Applying an OER catalyst to the anode prevents the COR to destroy the anode. Therefore, a reversal tolerant anode (RTA) is created. In this research, the RTA was made by the introduction of an OER catalyst (IrOx supported on TiOx) to the anode. Electrochemical investigations on the RTA were done with a Rotating Disc Electrode (RDE), which allowed applying potentials on the RTA that occur during fuel cell reversal. However, these potentials on an OER catalyst with a RDE set-up is known to be troublesome. This can be devoted to the formation of oxygen bubbles, which are hard to evacuate in a RDE set-up and block reactant. Therefore, a special accelerated stress test (AST) has been developed in this research to diminish the effects of oxygen bubbles. This AST was used to investigate the effects of different processing techniques on the RTA performance and durability at fuel cell reversal potentials. Pt/C and IrOx/TiOx particles could be differentiated into bigger and smaller particles on the micrometer scale based on different ball milling times used during processing. This was confirmed by laser diffraction measurements, which supplied information on the particle size distribution (PSD). Besides, differences in the catalyst layer structure were confirmed by a laser microscope. In the AST, it was found that the activity towards the OER was higher for smaller particles, which could be explained by the increased surface area. It was found for all samples in the AST that there was loss of OER activity and Electrochemical Surface Area (ECSA) of Pt. Impedance spectroscopy, XPS and SEM/EDS showed that these losses could highly probable be devoted to the decrease of the ionomer content. Finally, to mimic real fuel cell reversal conditions in a RDE set-up, adjusted chronopotentiometry measurements were developed and applied. It was found that the higher OER active smaller particles had a worse tolerance against fuel cell reversal than the bigger particles.