Core-shell compositional fine structures of dealloyed PtN nanoparticles and their impact on oxygen reduction catalysis
by Lin Gan, Marc Heggen, Stefan Rudi and Peter Strasser
Using aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy line profiles with Ångström resolution, novel core-shell fine structures in a series of catalytically active dealloyed Pt_(x)Ni(1-x) core-shell nanoparticles have been uncovered, showing the formation of unusual near-surface Ni-enriched inner shells. The radial location and the composition of the Ni-enriched inner shells were found to be sensitively dependent on the initial alloy compositions. It is discussed how these self-organised Ni-enriched inner shells play a key role in maintaining surface lattice strain and thus control the surface catalytic activity for oxygen reduction.
Lin Gan, Marc Heggen, Stefan Rudi and Peter Strasser: Core shell compositional fine structures of dealloyed PtN nanoparticles and their impact on oxygen reduction catalysis, Nano Letters 12 (2012) 5423-5430