One of the most important practical issues in low-temperature fuel-cell catalyst degradation is platinum dissolution. According to the literature, it initiates at 0.6-0.9 VRHE, whereas previous time- and potential-resolved inductively coupled plasma mass spectrometry (ICP-MS) experiments, however, revealed dissolution onset at only 1.05 VRHE. In this manuscript, the apparent discrepancy is addressed by investigating bulk and nanoparticulated catalysts. It is shown that, given enough time for accumulation, traces of platinum can be detected at potentials as low as 0.85 VRHE. At these low potentials, anodic dissolution is the dominant process, whereas, at more positive potentials, more platinum dissolves during the oxide reduction after accumulation. Interestingly, the potential and time dissolution dependence is similar for both types of electrode. Dissolution processes are discussed with relevance to fuel-cell operation and plausible dissolution mechanisms are considered.
Keywords: electrochemistry; energy conversion; fuel cells; mass spectrometry; platinum.