Nanothermodynamics on the Example of Metallic Nanoparticles

Abstract

After analyzing the problem of extending the Gibbs surface excess method to nanoscale objects, two different approaches to the application of the Gibbs method for finding the specific surface energy of metal nanoparticles are being considered. The first approach involves the use of the local coordination approximation to estimate the specific surface energy of icosahedral FCC metal nanoparticles (magic nanoclusters). For the first time, we have drawn attention to the fact that for such a nanocluster, it is possible to accurately calculate both the fraction of surface atoms and the values of the first coordination number in the inner region of the nanoparticle and on its surface (faces, edges, and vertices). The second approach implemented by us earlier for spherical Au nanoparticles and here for FCC Pt nanoparticles, involves the complex application of the Gibbs method adapted for nanoparticles and the results of molecular dynamics simulation. Estimates using both approaches agree with the experimental values of the surface energy corresponding to the flat surface of the bulk phases of the corresponding metals. In the final section of the work, the limits of applicability of thermodynamics to nanosystems are discussed.