title: Understanding and controlling the structure and segregation behaviour of AuRh nanocatalysts.
abstract: Heterogeneous catalysis, which is widely used in the chemical industry, makes a great use of supported late-transition-metal nanoparticles, and bimetallic catalysts often show superior catalytic performances as compared to their single metal counterparts. In order to optimize catalyst efficiency and discover new active combinations, an atomic-level understanding and control of the catalyst structure is desirable. In this work, the structure of catalytically active AuRh bimetallic nanoparticles prepared by colloidal methods and immobilized on rutile titania nanorods was investigated using aberration-corrected scanning transmission electron microscopy. Depending on the applied post-treatment, different types of segregation behaviours were evidenced, ranging from Rh core - Au shell to Janus via Rh ball - Au cup configuration. The stability of these structures was predicted by performing density-functional-theory calculations on unsupported and titania-supported Au-Rh clusters; it can be rationalized from the lower surface and cohesion energies of Au with respect to Rh, and the preferential binding of Rh with the titania support. The bulk-immiscible AuRh/TiO2system can serve as a model to understand similar supported nanoalloy systems and their synergistic behaviour in catalysis.
authors.affiliation: Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), UMR 5256 CNRS &Université Claude Bernard - Lyon 1, 2 avenue Albert Einstein, F-69626 Villeurbanne, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Piccolo
authors.affiliation: Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, United Kingdom.
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Li
authors.affiliation: School of Chemistry, University of Birmingham, Birmingham B15 2TT, United Kingdom.
authors.forename: Ilker
authors.initials: I
authors.lastname: Demiroglu
authors.affiliation: Normandie Université, UNIROUEN, INSA Rouen, CNRS, Groupe de Physique des Matériaux, 76000, Rouen, France.
authors.forename: Florian
authors.initials: F
authors.lastname: Moyon
authors.affiliation: Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), UMR 5256 CNRS &Université Claude Bernard - Lyon 1, 2 avenue Albert Einstein, F-69626 Villeurbanne, France.
authors.forename: Zere
authors.initials: Z
authors.lastname: Konuspayeva
authors.affiliation: Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), UMR 5256 CNRS &Université Claude Bernard - Lyon 1, 2 avenue Albert Einstein, F-69626 Villeurbanne, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Berhault
authors.affiliation: Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), UMR 5256 CNRS &Université Claude Bernard - Lyon 1, 2 avenue Albert Einstein, F-69626 Villeurbanne, France.
authors.forename: Pavel
authors.initials: P
authors.lastname: Afanasiev
authors.affiliation: Normandie Université, UNIROUEN, INSA Rouen, CNRS, Groupe de Physique des Matériaux, 76000, Rouen, France.
authors.forename: Williams
authors.initials: W
authors.lastname: Lefebvre
authors.affiliation: Department of Physics, University of York, York, YO10 5DD, United Kingdom.
authors.forename: Jun
authors.initials: J
authors.lastname: Yuan
authors.affiliation: School of Chemistry, University of Birmingham, Birmingham B15 2TT, United Kingdom.
authors.forename: Roy L
authors.initials: RL
authors.lastname: Johnston