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Segregation effects on the properties of (AuAg)

DOI: 10.1039/C4CP00753K DOI Help

Authors: A. L Gould (Rutherford Appleton Laboratory; University College London (UCL)) , C. J. Heard (University of Birmingham) , A. J. Logsdail (Kathleen Lonsdale Materials Chemistry) , C. R. A. Catlow (Kathleen Lonsdale Materials Chemistry)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Chemistry Chemical Physics , VOL 16 , PAGES 21049 - 21061

State: Published (Approved)
Published: April 2014

Open Access Open Access

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.

Subject Areas: Chemistry

Technical Areas: