title: Segregation effects on the properties of (AuAg)₁₄₇.
abstract: AuAg nanoclusters are promising supported co-catalysts for photocatalytic hydrogen reduction. However, beyond the quantum regime (N > 100) little is known about how the electronic properties of these nanoparticles are affected by chemical ordering. We investigate the effects of chemical ordering on the properties of 147-atom cuboctahedral AuAg nanoclusters, using empirical potentials coupled with an atomic-swap basin-hopping search to optimise the elemental distribution, with the lowest energy arrangements then reminimised using Density Functional Theory (DFT). Force-field calculations show Au atoms preferentially occupy sub-surface positions in the bimetallic structures, which results in the formation of a pseudo-onion structure for Ag-rich compositions. At the DFT-level, however, an Ag core surrounded by an Au shell (Ag@Au) is energetically favoured, as electron density can be drawn more readily when Au atoms are positioned on the nanocluster surface, thus resulting in a partial negative charge. Core@shell configurations are analogous to structures that can be chemically synthesised, and further detailed electronic analysis is discussed in the context of nanocluster applications to co-catalysed photocatalysis.
authors.affiliation: Rutherford Appleton Laboratory, Harwell Oxford Didcot, Oxon, OX11 0FA, UK. a.gould@ucl.ac.uk.
authors.forename: A L
authors.initials: AL
authors.lastname: Gould
authors.forename: C J
authors.initials: CJ
authors.lastname: Heard
authors.forename: A J
authors.initials: AJ
authors.lastname: Logsdail
authors.forename: C R A
authors.initials: CR
authors.lastname: Catlow