Gold sponges prepared via hydrothermally activated self-assembly of Au nanoparticles

In this work, we describe a self-assembly approach for generation of nanostructured Au sponges with Au nanoparticles as starting building blocks. It is found that the hydrothermal condition is essential to detach surfactants and thus trigger the self-assembly of Au nanoparticles. The resultant Au sponges are comprised of finely branched nanowires whose diameters can be selected in the range of 15-150 nm. The sponge morphology can be further controlled by manipulating surfactant population, concentration of metallic nanoparticles, amount and type of alcohol solvent, process temperature and time, etc. In principle, this template-free approach can also be extended to large-scale three-dimensional organizations of other surfactant-capped transition/noble metal nanoparticles.