Degradation of Carbon-Supported Platinum-Group-Metal Electrocatalysts in Alkaline Media Studied by in Situ Fourier Transform Infrared Spectroscopy and Identical-Location Transmission Electron Microscopy

Alkaline fuel cells and electrolyzers have attracted increasing attention from the electrochemical community, and one of their supposed advantages is their greater electrode material stability in comparison to their proton-exchange membrane analogues. However, the stability of the core materials of fuel cells and electrolyzers in an alkaline environment cannot be taken for granted and remains understudied so far. Herein, using in situ Fourier transform infrared spectroscopy (FTIR), identical-location transmission electron microscopy (IL-TEM), X-ray photoelectron spectroscopy (XPS), and COads stripping techniques, we provide physical and chemical evidence that Pt-based nanocatalysts catalyze the electrochemical corrosion of the carbon support (Vulcan XC72). This is due to more facile oxidation of oxygen-containing surface groups of the carbon support upon adsorption of hydroxyl groups on the Pt-based surface. The degradation mechanism is, to some extent, similar for other carbon-supported Pt-group-metal (PGM) electrocatalysts. We propose that the extent of degradation of PGM/C nanoparticles in alkaline electrolytes scales with the electrocatalyst’s activity to electrooxidize CO, thereby providing a marker of the material’s propensity for degradation in an alkaline environment.