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

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.