Gold-draped surfaces sense, catalyse
doi:10.1038/nindia.2010.172 Published online 30 November 2010
Researchers have successfully used a new ionic liquid to synthesize and deposit thin films of gold nanoparticles (GNPs) on glass and quartz surfaces. The GNP-coated surfaces can sense the refractive index of various organic solvents and catalyse organic reactions.
To exploit the potential of ionic liquids, the researchers produced tetrabutylphosphonium citrate, a newly designed redox-active ionic liquid, and used it to deposit thin films of GNP on glass and quartz surfaces.
The thin films comprised nanoparticles with sizes between 15 nm and 50 nm. Similar thin films were also laid on easily available commercial substrates such as polystyrene, polypropylene, plain paper and cellophane paper.
The GNP thin films were very stable and could not be leached out after washing with either polar or non-polar solvents. The thin-film-coated surfaces were tested for their ability to sense refractive index using various organic solvents such as ethanol, dichloromethane, chloroform and toluene.
The thin-film-coated quartz surface responded well to changes in the dielectric constant of the local environment, making it potentially useful as a refractive index sensor. The study also indicated that the film-coated quartz surface catalysed the borohydride reduction of nitrophenol.
"This technique is simple, requires only a single step and does not use any sophisticated instruments," says lead researcher Tarun Mandal.