Approach to Fabricating a Compact Gold Nanoparticle Film with the Assistance of a Surfactant

We report a facile method to fabricate a compact Au nanoparticle film with the assistance of surfactants. First, the dodecanethiol-coated Au nanoparticles were floated on the surface of the toluene/acetonitrile solvent mixture and adjusted to an expanded dispersion by changing the mixture ratio. Silicone oil was then added as a surfactant to compress the floating nanoparticles from the original loose status to a closely packed arrangement that produced a compact nanoparticle film. The relationship of the compressed film area to the silicone oil concentration was plotted and compared to the surface tension curve of silicone oil. The results were quite consistent, suggesting that the surface location of the surfactant induced the nanoparticles' compression. The resulting nanoparticle film was uniform and sufficiently robust to be transferred to the solid substrate. Moreover, it could be applied to catalyze the reduction of 4-nitrophenol. Our study indicated that the utilization of surfactants to compress the well-dispersed nanoparticles on the liquid surface is a simple, fast, and adaptable method of fabricateing compact nanoparticle films with great promise for future applications.