Core-shell compositional fine structures of dealloyed Pt(x)Ni(1-x) nanoparticles and their impact on oxygen reduction catalysis.

Gan, Lin; Heggen, Marc; Rudi, Stefan; Strasser, Peter · Nano Lett · 2012

basic_science · Level V

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Abstract

Using aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy line profiles with Ångstrom resolution, we uncover novel core-shell fine structures in a series of catalytically active dealloyed Pt(x)Ni(1-x) core-shell nanoparticles, showing the formation of unusual near-surface Ni-enriched inner shells. The radial location and the composition of the Ni-enriched inner shells were sensitively dependent on the initial alloy compositions. We further discuss how these self-organized Ni-enriched inner shells play a key role in maintaining surface lattice strain and thus control the surface catalytic activity for oxygen reduction.