One of the key problems in studying alloy nanoparticle catalysis is their surface morphology and segregation behavior. We have developed an accurate embedded atom method (EAM) potential and employed it in the simulation of PdAu metal alloy nanoparticles. The potential was parameterized based on an extensive set of density-functional-theory (DFT) calculations of metal clusters in addition to bulk-alloy properties. The EAM potential accurately reproduces DFT energies of both bulk PdAu alloys and small nanoparticles. We utilized the developed EAM potential in a Monte Carlo simulation of PdAu nanoparticles ranging from 55-atom $\left(\sim 1\text{nm}\right)$ to 5083-atom particles $\left(\sim 4.5\text{nm}\right)$. The effects of different factors (particle size, temperature, and composition ratios) on the segregation behavior of PdAu alloy are examined. Our simulation results quantitatively reveal the extent of surface segregation and a strong dependence of surface morphology on the nanoparticle size.

• Received 2 March 2009

DOI:https://doi.org/10.1103/PhysRevB.80.035404