Structural change of carbon supported Pt nanocatalyst subjected to a step-like potential cycling in PEM-FC

Abstract In this paper we present detailed X-ray absorption fine structure (XAFS), X-ray diffraction (XRD) and transmission electron microscopy (TEM) investigations of the changes in the local geometric and electronic structure of Pt nanoparticles used as a cathode catalyst in proton exchange membrane fuel cell (PEMFC), working under controlled potential cycling conditions. The body of the results obtained suggests that in the first stage of \{PEMFC\} operation, small particle dissolution was a dominant process. Subsequent 100 h of work led to the progressive agglomeration of nanoparticles followed by a pronounced growth of the mean nanoparticle size. At the same time, high-quality \{XAFS\} spectra analysis demonstrated that negligible changes in structural local ordering and a slight increase in Pt 5d-electron density occurred during the whole \{FC\} operation period under consideration.