Bimetallic nanocatalysts (NCs) composed of two metal elements are a promising way to achieve high catalytic performance, based on so-called synergistic effects. In this context, we have designed bimetallic core-shell nanoparticles (NPs) combining a plasmonic metal Ag as core and a catalytic metal Pt as shell. Ag(at)Pt core-shell NPs were synthesized via a seed-mediated growth process allowing fine control of the Ag core size and Pt shell thickness. In a first step, Ag seeds (8-13nm) with a narrow size distribution (