AuPd Metal Nanoparticles as Probes of Nanoscale Thermal Transport in Aqueous Solution

Water- and alcohol-soluble AuPd nanoparticles have been investigated to determine the effect of the organic stabilizing group on the thermal conductance G of the particle/fluid interface. The thermal decays of tiopronin-stabilized 3−5-nm diameter AuPd alloy nanoparticles, thioalkylated ethylene glycol-stabilized 3−5-nm diameter AuPd nanoparticles, and cetyltrimethylammonium bromide-stabilized 22-nm diameter Au-core/AuPd-shell nanoparticles give thermal conductances G ≈ 100−300 MW m-2 K-1 for the particle/water interfaces, approximately an order of magnitude larger than the conductance of the interfaces between alkanethiol-terminated AuPd nanoparticles and toluene. The similar values of G for particles ranging in size from 3 to 24 nm with widely varying surface chemistry indicate that the thermal coupling between AuPd nanoparticles and water is strong regardless of the self-assembled stabilizing group.