Wettability-dependent thermal transport at the Fe nanoparticle-water interface: Molecular dynamics simulations

Abstract

Nanoparticles are pivotal in applications such as solar thermal utilization, drug delivery, and water treatment. However, the microscopic mechanisms of heat transfer between nanoparticles and water, especially considering wettability effects, remain poorly understood. This study aims to investigate the interfacial heat transport properties of Fe nanoparticles-water using molecular dynamics simulations with varying levels of wettability. And the results indicate that the thermal conductance at the interface between Fe nanoparticles and water is 97.9 × 108 W/m2 K. The study also reveals an oscillatory pattern in the water density near the Fe nanoparticle interface, resulting in a distinct “double-density peak” With increased wettability, this peak density consistently grows, while the thickness of the adjacent solid-like layer remains relatively unchanged. Through the analysis of the vibrational density of states at the interface, the study reveals the microscopic mechanism by which wettability affects the thermal conductance of the Fe nanoparticles-water interface. Enhanced wettability improves the coupling of low-frequency phonon modes across the solid-liquid boundary, increasing thermal energy transfer efficiency. The study further identifies that low-frequency transverse modes play a vital role in heat transfer at the interface. Consequently, these insights provide a valuable theoretical framework for comprehending heat transport mechanisms at soft-hard interfaces.