  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 surface charge and the 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 threefold increase of the Kapitza conductance for a nanoparticle
surface charge +2 e/nm2. This enhancement is shown to be approximately
independent of surface wettability, charge spatial distribution, and salt
concentration. This allows us to express the Kapitza conductance enhancement in
terms of surface charge density on a master curve. Finally, we interpret the
increase of the Kapitza conductance as a combined result of a shift in the
water density distribution toward the charged nanoparticle and an accumulation
of the counter-ions around the nanoparticle surface which increase the
Coulombic interaction between the liquid and the charged nanoparticle.
