Enhanced Heat Flow between Charged Nanoparticles and an Aqueous Electrolyte

Abstract

Heat transfer through the interface between a metallic nanoparticle and an electrolyte solution has great importance in a number of applications, ranging from nanoparticle-based cancer treatments to nanofluids and solar energy conversion devices. However, the impact of the surface charge and dissolved ions on heat transfer has been scarcely explored so far. In this study, we compute the interface thermal conductance between hydrophilic and hydrophobic charged gold nanoparticles immersed in an electrolyte using equilibrium molecular dynamics simulations. Compared with an uncharged nanoparticle, we report a 3-fold increase of the Kapitza conductance for a nanoparticle surface charge of +320 mC/m 2 . This enhancement is shown to be approximately independent of the surface wettability, charge spatial distribution, and salt concentration. This allows us to express the Kapitza conductance enhancement in terms of the surface charge density on a master curve. Finally, we interpret the increase of the Kapitza conductance as a combined result of the shift of the water density distribution toward the charged nanoparticle and an accumulation of the counterions around the nanoparticle surface which increase the Coulombic interaction between the liquid and the charged nanoparticle. These considerations help us to apprehend the role of ions in heat transfer close to electrified surfaces.

Interfacial Thermal Transport and Electrical Performances of Supercapacitors with Graphene/Carbon Nanotube Composite Electrodes

“…This thermal resistance, due to the disparity in the electronic and vibrational characteristics of the two materials in contact, is called ITR and is given by R K = normalΔ T J normalq where J q is the heat flux across the interface and Δ T is the temperature difference between the materials in contact. Computational studies have proven valuable in developing an understanding of the fundamental mechanism of interfacial thermal transport between solid–fluid interfaces, − including graphene–ionic liquid (IL) interfaces which are more relevant for supercapacitor thermal transport . Qian et al investigated the ITR and structure at the interface between graphene and the IL and observed that the molecular orientation of ions near the solid surface dominates the degree of heat transfer at the imidazolium-based IL-graphene interface.…”