Résumé
We combine electron microscopy measurements of the surface compositions in Cu-Au nanoparticles andatomistic simulations to investigate the effect of gold segregation. While this mechanism has beenextensively investigated within Cu-Au in the bulk state, it was never studied at the atomic level innanoparticles. By using energy dispersive x-ray analysis across the (100) and (111) facets of nanoparticles,we provide evidence of gold segregation in Cu3Au and CuAu3 nanoparticles in the 10 nm size range grownby epitaxy on a salt surface with high control of the nanoparticles morphology. To get atomic-scale insightsinto the segregation properties in Cu-Au nanoparticles on the whole composition range, we performMonte Carlo calculations employing N-body interatomic potentials highlighting a complete segregation ofAu in the (100) and (111) facets for gold nominal composition above 70% and 60%, respectively.Furthermore, we show that there is no size effect on the segregation behavior since we evidence the sameoscillating concentration profile from the surface to the nanoparticle’s core as in the bulk. These resultsshed new light on the interpretation of the enhanced reactivity, selectivity, and stability of Cu-Aunanoparticles in various catalytic reactions.