Evaporation-induced ordered honeycomb structures of gold nanoparticles at the air/water interface.

The breath figure method was used to prepare dodecanethiol-capped gold nanoparticle macroporous structures with pore diameters from 1.7 to 3.5 mum on an air/water interface. A two-step procedure is proposed for the fabrication of these macroporous structures, by forming a surfactant monolayer on water, and drop-casting a gold nanoparticle dispersion in chloroform onto the surfactant monolayer. The self-assembled films are easily transferred from the water surface onto different substrates and were characterized by TEM, SEM, and AFM. Ordered honeycomb structures with different pore arrays (perforated monolayer films, hexagonal networks and alveoli-like porous films) were obtained. The change in morphology is concentration dependent, and deformed structures with elliptic honeycomb networks are also observed. In addition, honeycomb films using gold nanoparticles stabilized by a weakly bound ligand (dioctadecyldimethylammonium chloride) were formed by the same technique. These films have potential as substrates for surface-enhanced Raman spectroscopy.