Implications of the Interface Modeling Approach on the Heat Transfer across Graphite–Water Interfaces

Abstract

In this investigation, the thermal transport across graphite−water interfaces was studied by means of nonequilibrium classical molecular dynamics (NEMD) simulations. The main focus of this work was the assessment of the interface modeling approach of the nonbonded interactions, where empirical models optimized for predicting an experimental wetting condition were compared against interface models derived from multibody electronic structure methods. To understand the mechanisms involved in the interfacial heat transfer, spectral heat flux mapping and phonon dynamics (spectral energy density) analyses were implemented to query the vibrational composition of interfacial heat transfer. Aside from the NEMD formulation, a modified acoustic mismatch model including interfacial interactions was utilized. The results obtained from this investigation are twofold. (i) The minimum of the adsorption energy curve (binding energy) can be used to fully describe the wetting response of an atomically dense surface, such as graphene/graphite, as irrespective of the interface modeling approach, a linear relationship exists between the work of adhesion and the binding energy. (ii) The sole effect of the solid−liquid affinity, characterized by wetting behavior, does not provide a conclusive description of the interfacial heat transfer when different interface models are used, which is consistent with recent experimental reports. Alternatively, the interfacial liquid depletion provided a sound explanation of the nonconclusive observations derived from correlating wetting behavior to thermal transport. Furthermore, the critical impact that the modeling techniques have has been brought to light in the description of heat transfer across solid−liquid interfaces. These findings call to review the modeling efforts of interfacial heat transfer when using empirical mixing rules or matching wetting behavior to model solid−liquid interfaces.

In Situ Photothermal Response of Single Gold Nanoparticles through Hyperspectral Imaging Anti-Stokes Thermometry

“…Contrary to the hydrophilic surface of polyelectrolyte-coated glass, graphene-coated glass is highly hydrophobic , and therefore a higher R K resistance is expected between the water and the hydrophobic graphene-coated glass. Moreover, very high values of R K between graphene and SiO 2 interfaces have been measured, including a dramatically five-order of magnitude increase in R K when the graphene is not in full contact with glass but presents some corrugation of nm-sized height.…”

Molecular Dynamics Simulations of Wettability, Thermal Transport, and Interfacial Liquid Structuring at the Nanoscale in Polar Solid–Liquid Interfaces

“…If the interplay between atomic topography and energy of interaction permits the water molecules to concentrate and get closer or even infiltrate past the outermost layer of solid atoms, the in-plane vibrations are enhanced. Alternatively, the out-of-plane modes show larger contributions for interfaces featuring flatter energy landscapes, larger solid–liquid equilibrium distances, or low interfacial liquid concentration, which are the result of large repulsion regions near the substrate, i.e., graphite, silicon carbide (SiC), and silicon (Si) in the (111) orientation. ,, The composition of q S–L (ω) can be correlated with the interfacial entropy calculations in Figure a. Low Δ S SL , associated with a small bulk-to-interface water structuring change, indicates that interfacial water molecules experienced a smoother energy landscape, thus a prohibitive path for in-plane-mode dominant heat transfer.…”

Effects of the Interfacial Modeling Approach on Equilibrium Calculations of Slip Length for Nanoconfined Water in Carbon Slits

“…These results echo those found for heat transfer across solid−liquid interfaces, a different interfacial transport property, for different solid substrates. 31,33,86 These aforementioned findings also reflect a poor description of the interfacial heat transfer as a function of the surface wettability, which then is improved drastically by considering the liquid depletion length. In both cases, δ quantifies the availability of interfacial carriers, of energy for heat transfer, and momentum for hydrodynamic slip.…”

“…On the wettability side of the theory, scaling functions between L s and the contact angle (θ) and between L s and the density depletion length (δ) have been reported in the literature. As a related topic, investigations on thermal transport across solid–liquid interfaces have shown that relationships based on wettability do not provide a consistent description of the thermal boundary conductance, while relations using the interfacial liquid structuring (δ) were able to describe the behavior of the interfacial energy transport. − Therefore, it is necessary to carefully address the applicability of describing hydrodynamic slip using wettability and interfacial liquid properties. Nevertheless, evidence indicates that the explanation for the physics governing the hydrodynamic slip is concealed behind the physical characteristics of the solid–liquid interface.…”