Abstract

The Interfacial Thermal Conductance (ITC) is a fundamental property of materials and has particular relevance at the nanoscale. The ITC quantifies the thermal resistance between materials of different compositions or between fluids in contact with materials. Furthermore, the ITC determines the rate of cooling/heating of the materials and the temperature drop across the interface. Here, we propose a method to compute local ITCs and temperature drops of nanoparticle-fluid interfaces. Our approach resolves the ITC at the atomic level using the atomic coordinates of the nanomaterial as nodes to compute local thermal transport properties. We obtain high-resolution descriptions of the interfacial thermal transport by combining the atomistic nodal approach, computational geometry techniques, and "computational farming" using non-equilibrium molecular dynamics simulations. We use our method to investigate the ITC of nanoparticle-fluid interfaces as a function of the nanoparticle size and geometry, targeting experimentally relevant structures of gold nanoparticles: capped octagonal rods, cuboctahedrons, decahedrons, rhombic dodecahedrons, cubes, icosahedrons, truncated octahedrons, octahedrons, and spheres. We show that the ITC of these very different geometries varies significantly in different regions of the nanoparticle, increasing generally in the order face < edge < vertex. We show that the ITC of these complex geometries can be accurately described in terms of the local coordination number of the atoms in the nanoparticle surface. Nanoparticle geometries with lower surface coordination numbers feature higher ITCs, and the ITC generally increases with the decreasing particle size.

Highlights

  • Nanoparticles (NPs) have garnered increasing attention due to their wide range of applications in medicine, materials science, and catalysis,1–5 stemming from the significant dependence of their physicochemical properties with size and shape

  • We find that the interfacial thermal conductance, heat flux, and temperature gradients are independent within the statistical uncertainty of our computations on the thermostatting frequency

  • We have introduced a computational approach to calculate the Interfacial Thermal Conductance (ITC) of nanomaterial–fluid interfaces

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Summary

Introduction

Nanoparticles (NPs) have garnered increasing attention due to their wide range of applications in medicine, materials science, and catalysis, stemming from the significant dependence of their physicochemical properties with size and shape. Metallic nanoparticles have attracted considerable interest due to their efficient conversion of light into heat, which provides unique opportunities to generate and control temperature fields at the nanoscale.. The unique capabilities of nanomaterials for light/heat conversion have motivated the development of a new research field, thermoplasmonics, which is impacting several areas: hot-electron chemistry, light harvesting, microfluidics, and photothermal therapies. Predicting the heat fluxes and temperature fields emerging from these hot particles is an important challenge. Addressing this challenge will allow significant advances in many areas from medicine to material processing

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