Atomic scale insight on the increased stability of tungsten modified platinum/carbon fuel cell catalysts

The limited stability of carbon-supported Pt catalysts for the oxygen reduction reaction is a key obstacle for their commercial application in fuel cells. Here we report on the properties of a tungsten-modified Pt/C catalyst that shows enhanced stability under potential cycling conditions compared to a reference Pt/C catalyst. Although routine structural investigation by XRD and TEM show an inhomogeneous distribution of tungsten species on the modified catalyst surface, X-ray photoelectron spectroscopy points to an overall changed catalytic behavior of Pt nanoparticles. Aberration-corrected atomic-scale imaging reveals the presence of homogeneously dispersed tungsten atomic species that decorate the surface of the carbon support and the Pt nanoparticles. The presented results demonstrate that detailed and localized imaging at the atomic scale is essential for the identification of the relevant species amongst spectator phases and thus, for the understanding of the improved integral behavior of a modified catalyst.