First-principles study of the stability of bimetallic PdPt nanoparticles under a finite temperature

TL;DR

This study uses first-principles calculations to analyze how vibrational and configurational entropy influence the stability of PdPt bimetallic nanoparticles at finite temperatures, highlighting the dominant role of configurational entropy.

Contribution

It provides a detailed first-principles analysis of vibrational and configurational entropy effects on nanoparticle stability, emphasizing the importance of configurational entropy in stability assessments.

Findings

Configurational entropy significantly impacts nanoparticle stability.

Vibrational energy and entropy are large but have limited effect on free energy differences.

Configurational entropy dominates the stability considerations of PdPt nanoparticles.

Abstract

To understand the vibrational and configurational entropy effects for the stability of core-shell and solid-solution bimetallic nanoparticles, we theoretically investigated the excess energy of PdPt nanoparticles, adopting the (PdPt)201 model of ca. 2 nm by using the density functional method. The vibrational energy and entropy terms contributed to the total energy of both core-shell and solid-solution nanoparticles. The configurational entropy term was defined only for the solid-solution nanoparticles. Although the absolute values of vibrational energy and entropy terms were much larger than that of configurational entropy term, their contributions were limited in the form of excess free energy due to the small difference between different atomic configurations. The large contribution of configurational entropy term to the excess free energy was clearly confirmed from our first-principles calculations. To estimate the stability of core-shell and solid-solution metal nanoparticles based on the excess energy, the configurational entropy term was the dominant factor.