Investigating the corrosion of high surface area carbons during start/stop fuel cell conditions: A Raman study

In the present study we investigated the corrosion of high surface area carbons, which are used as supports for electrocatalysts in polymer electrolyte membrane fuel cells (PEMFCs). Our main focus thereby was to scrutinize if Pt catalyses carbon corrosion. For this aim we employed Raman spectroscopy for studying two different carbon blacks (CBs), i.e., Vulcan XC72R (Cabot Corporation) and Ketjenblack EC-300J (AkzoNobel), both covered with Pt NPs as well as uncovered. In order to significantly degrade the CBs, we used a start/stop protocol recommended by the FCCJ (Fuel Cell Commercialization Conference of Japan) as an accelerated stress test (AST). The relative high potentials involved, i.e., 1–1.5 VRHE, inflicted a significant different electrochemical surface area loss (ECSA) of the two Pt NP covered CBs, revealing the less stable character of Vulcan XC72R as compared to Ketjenblack EC-300J. Raman spectroscopy revealed clear changes in the carbon due to potential cycling. The most significant changes were found for the Vulcan support, with two pronounced peaks above 1730 cm−1 appearing in the spectra. The peaks can be assigned to the partial oxidation of the carbon support. Interestingly, the same changes due to the AST have been found both for the Pt loaded and the bare Vulcan support. Unlike on Vulcan, on Ketjenblack no unambiguous peaks at these Raman shifts were detected after the AST, but only a small shoulder. Again no significant difference was found between the spectra of the treated bare Ketjenblack and the Pt NP covered support.