(684a) A Simple Coordination-Based Model for Bimetallic Nanoparticles

The stability of nanoparticle catalysts to phenomena such as sintering is of fundamental importance to heterogeneous catalysis.¹ Great effort has been dedicated to understanding the mechanisms of nanoparticle sintering, which range from single-atom Ostwald ripening to whole-particle migration depending on reaction conditions and the nature of the catalyst support.^2-3 In recent work, we presented a kinetic Monte Carlo (kMC) algorithm to describe the surface migration of supported platinum nanoparticles.⁴ We seek to develop a more general understanding of nanoparticle structural evolution under reaction conditions to design catalysts with enhanced stability.

In this presentation, we demonstrate a new model for predicting the energies of monometallic and bimetallic configurations of fcc metal atoms based only on the identity of the metals and the coordination number of individual atoms. Using parameters obtained from a small set of density functional theory calculations for monometallic surface adsorption, we reliably predict energies of bimetallic nanoparticles with varying size, shape, composition, and atomic configuration. In combination with a kMC algorithm, this model enables a deeper understanding of the dynamic nature of supported nanoparticle catalysts under reaction conditions and subsequent design of catalysts with improved resistance to sintering.

¹C.H. Bartholomew, Appl Catal A-Gen 212, 17 (2001)
²E. Ruckenstein, B. Pulvermacher, J Catal 245, 224 (1973)
³P. Voorhees, J Stat Phys 38, 231 (1985)
⁴L. Li, P. N. Plessow, M. Rieger, S. Sauer, R. S. Sánchez-Carrera, A. Schaefer, F. Abild-Pedersen, J Phys Chem C 121, 4261 (2017)