Abstract
Hydrogen can be depleted during the operation of proton exchange membrane fuel cells (PEMFCs), then protons would be provided instead by oxidizing the carbon support with water at the anode. This undesired reaction can cause reversal cell voltage, resulting in sudden cell stop and pinhole generation. A reversal tolerant anode (RTA) has been proposed to prevent the voltage reversal by adding a catalyst that electrolyzes water. Here, IrOx nanoparticles are deposited on the commercial Pt/C in a monodisperse manner, and used as RTA. Comparing to the conventionally used RTA, which is a physical mixture of IrOx particles made by Adams fusion method and Pt/C, the monodispersed IrOx catalyst shows 4 times higher reversal tolerance time than the conventional RTA catalyst. In order to investigate the effect of Ir oxidation state on the reversal tolerance, metallic Ir nanoparticles are also prepared and compared with oxidic IrOx. The metallic Ir nanoparticles show very poor reversal tolerance because competitive hydrogen oxidation reactions also occur on the Ir site and the Ir site is easily poisoned by CO species. Monodisperse oxidic IrOx nanoparticles exhibit the best voltage reversal tolerance.
Published Version
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