Interfacial Thermal Conductance of Thiolate-Protected Gold Nanospheres

TL;DR

This study uses molecular dynamics simulations to analyze how ligand properties influence the interfacial thermal conductance of gold nanoparticles, revealing mechanisms that enhance heat transfer at the nanoscale.

Contribution

It provides new insights into the mechanisms affecting thermal conductance at nanoparticle interfaces, including ligand effects and solvent interactions.

Findings

Ligand-protected particles have higher thermal conductance than bare metal-solvent interfaces.

Ligand chain length and rigidity significantly influence solvent-ligand interpenetration and vibrational overlap.

Smallest particles show notable surface corrugation affecting conductance.

Abstract

Molecular dynamics simulations of thiolate-protected and solvated gold nanoparticles were carried out in the presence of a non-equilibrium heat flux between the solvent and the core of the particle. The interfacial thermal conductance ($G$) was computed for these interfaces, and the behavior of the thermal conductance was studied as a function of particle size, ligand flexibility, and ligand chain length. In all cases, thermal conductance of the ligand-protected particles was higher than the bare metal-solvent interface. A number of mechanisms for the enhanced conductance were investigated, including thiolate-driven corrugation of the metal surface, solvent ordering at the interface, solvent-ligand interpenetration, and ligand ordering relative to the particle surface. Only the smallest particles exhibited significant corrugation. All ligands permitted substantial solvent-ligand interpenetration, and ligand chain length has a significant influence on the orientational ordering of interfacial solvent. Solvent-ligand vibrational overlap, particularly in the low frequency range ($< 80 \mathrm{cm}^{-1}$) was significantly altered by ligand rigidity, and had direct influence on the interfacial thermal conductance.