Enhanced Heat Flow between Charged Nanoparticles and an Aqueous Electrolyte

Area of Science:

• Interface Heat Transfer
• Nanoparticle Science
• Physical Chemistry

Background:

• Heat transfer at nanoparticle-electrolyte interfaces is vital for applications such as cancer therapy, nanofluids, and solar energy.
• The influence of surface charge and dissolved ions on this heat transfer remains largely unexplored.

Purpose of the Study:

• To investigate the effect of surface charge and electrolyte ions on the interface thermal conductance of gold nanoparticles.
• To quantify the enhancement in heat transfer due to nanoparticle surface charge.

Main Methods:

• Utilized equilibrium molecular dynamics simulations to compute interface thermal conductance.
• Simulated hydrophilic and hydrophobic charged gold nanoparticles immersed in an electrolyte solution.

Main Results:

• A threefold increase in Kapitza conductance was observed for a nanoparticle surface charge of +320 mC/m² compared to uncharged nanoparticles.
• The enhancement was largely independent of surface wettability, charge distribution, and salt concentration.
• A master curve was developed relating Kapitza conductance enhancement to surface charge density.

Conclusions:

• Increased Kapitza conductance is attributed to altered water density distribution and counterion accumulation near the charged nanoparticle surface.
• Enhanced Coulombic interactions between the liquid and the charged nanoparticle contribute to improved heat transfer.
• Provides insights into the role of ions in heat transfer phenomena at electrified surfaces.