Structure of Pd/Au Alloy Nanoparticles from a Density Functional Theory-Based Embedded-Atom Potential

Abstract

On the basis of DFT results for a set of representative bulk, surface, and cluster systems, we determined a new embedded-atom potential for Pd/Au alloys. This embedded-atom approach accurately reproduces DFT properties of such alloy systems. We applied this potential in Monte Carlo simulations to study the effects of temperature and composition on the structure and bonding of Pd/ Au alloy nanoparticles up to 5 nm in diameter. We characterized the structure of those particles by evaluating the gold concentration at the surface and in the interior, the coordination numbers of atoms, the nature of Pd entities at the surface, and the number of suggested active sites for vinyl-acetate formation.

Size-dependent properties of transition metal clusters: from molecules to crystals and surfaces – computational studies with the program ParaGauss

“…This is in part due to the large number of possible compositions and in part because the structural motifs preferred in larger particles may require a certain size to evolve. 159 In view of the lower cohesive energy estimated for bulk Au compared to Pd, 49 it was not unexpected that the Monte Carlo simulations revealed a preference for higher Au concentrations at the particle surface, while the first subsurface layer was always found to be enriched in Pd. 236,237 EAM descriptions are usually employed for exploring bulk materials.…”

“…Fig. 159 Given the results, the PAWPW method was considered as the best approximate ionic core treatment for extended systems (Fig. 4 in view of their erratic behavior.…”

“…227 Although the resulting particles are far from uniform, such nanoalloys can be synthesized with different compositions for their surface and core moieties. 159 Recently, an efficient empirical, topology-based description was suggested for alloy NPs, 233 but a comprehensive and accurate electronic structure treatment remains next to impossible. 159 Recently, an efficient empirical, topology-based description was suggested for alloy NPs, 233 but a comprehensive and accurate electronic structure treatment remains next to impossible.…”

“…159 Recently, an efficient empirical, topology-based description was suggested for alloy NPs, 233 but a comprehensive and accurate electronic structure treatment remains next to impossible. 159,234,235 That study of Pd/Au nanoalloy particles addressed nuclearities ranging from 309 to 5083 and different alloy compositions, Pd 0.25 Au 0.75 , Pd 0.5 Au 0.5 , and Pd 0.75 Au 0.25 . Nevertheless, segregation and diffusion processes in Pd/Au nanoalloys were examined with Monte Carlo simulations 159,234,235 based on empirical force fields that rely on the embedded atom method (EAM).…”

Comment on “First-principles-based embedded atom method for PdAu nanoparticles”

“…Recently, we developed in the same spirit a new set of EAM parameters [16] for applications to Pd-Au nanoalloy particles where the set of training systems included more surfaces of alloys and more alloy clusters of at least 147 atoms, instead of 55 atoms as in the previous set [1].…”