Heterogeneous thermal conductance of nanoparticle–fluid interfaces: An atomistic nodal approach

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.

Size-dependent effects of the thermal transport at gold nanoparticle–water interfaces

“…5c that the thermal conductance increases when the coordination number increases. This conclusion is compatible with the results of Jiang et al [41], in spite of the fact that they consider different nanoparticle shapes without changing the nanoparticle size, and a different solvent ( monoatomic Lennard-Jones fluid). The correlation between the interface conductance and the coordination number seems to have general character regardless of the fluid molecular structure, at least for relatively simple molecular fluids.…”

Controlling local thermal gradients at molecular scales with Janus nanoheaters

“…To perform our analysis, we use the Atomistic Nodal Approach (ANA) introduced recently to quantify local changes in the thermal transport of nanoscale materials. 27 We demonstrate that the interfacial Kapitza conductance features a sharp transition (<1 nm), at the boundary separating the two components of the JNPs. This result opens new avenues to design Janus nanoheaters for spatial control of heat transport, using the Kapitza conductance of the homogeneous materials as input.…”

“…Furthermore, the interfacial thermal conductance varies with particle curvature and size, 33 as the ITC depends on the local coordination of the nanoparticle surface atoms. 27 Since the nanoparticle composition determines the anisotropy of heat transport discussed here, the discussions presented below hold for larger nanoparticles too.…”

“…The stationary approach offers a good signal-to-noise ratio and the setup mimics the experimental system, where the particle and the fluid are, naturally, at different temperatures. We computed the interfacial thermal conductance projected on each atom, using the recently introduced Atomistic Nodal Approach , 27 which provides a full spatial resolution of the interfacial Kapitza resistance, R K , defined by,where G K is the interfacial thermal conductance (ITC), J q is the heat flux at the particle-fluid interface, and Δ T is the temperature jump at the interface. We provide in the Methods section and the ESI† details on the calculation of the temperature and the heat flux (see section 2.1 in the ESI†).…”

Thermal conductance of the water–gold interface: The impact of the treatment of surface polarization in non-equilibrium molecular simulations

“…The importance of wettability on the ITC was analyzed recently, showing that the conductance increases with the hydrophilicity (wettability) of surfaces in contact with water. 13 Studies of flat 14 and curved-nanometer size 15,16 surfaces provide a correlation between surface wettability, surface structure, 17 interfacial width, 18 and thermal conductance. Recent works 19 demonstrated a correlation between interfacial fluid adsorption and thermal conductance of liquid-vapor interfaces.…”