Temperature and curvature-dependent thermal interface conductance between nanoscale-gold and water from molecular simulation

Plasmonic gold nanoparticles (AuNPs) can convert laser irradiation into thermal energy and act as nano heaters in avariety of applications. Although the AuNP-water interface is an essential part of the plasmonic heating process,there is a lack of mechanistic understanding of how interface curvature and the heating itself impact interfacial heattransfer. Here, we report atomistic molecular dynamics simulations that investigate heat transfer through nanoscalegold-water interfaces. We confirmed that interfacial heat transfer is an important part of AuNP heat dissipation inAuNPs with diameter less than 100 nm, particularly for small particles with diameter≤10 nm. To account forvariations in the gold-water interaction strength reported in the literature, and to implicitly account for differentsurface functionalizations, we modeled a moderate and a poor AuNP-water wetting scenario. We found that thethermal interface conductance increases linearly with interface curvature regardless of the gold wettability, while itincreases non-linearly, or remains constant, with the applied heat flux under different wetting conditions. Our analysissuggests the curvature dependence of the interface conductance is due to the changes in interfacial water adsorption,while the temperature dependence is caused by heat-induced shifts in the distribution of water vibrational states.Our study advances the current understanding of interface thermal conductance for a broad range of applications.