Quick and surfactant-free dispersion of various carbon nanoparticles in aqueous solution as casting technique for devices

Tremendous applications of carbon-based nanomaterials need the individualization of particles in the liquid phase, preferably in an aqueous solution. Currently, one of the main challenges is how to obtain highly monodispersed and high-quality colloidal solutions and make it usable in electronic devices without performing badly. In this study, carbon nanoparticles (i.e., fullerenes, carbon nanotubes, graphene) were individualized and stabilized well in an aqueous solution by using a novel cutting-edge dispersion technique using sodium hypochlorite (NaClO) and sodium bromide (NaBr) assisted by brief low-power sonication treatment. This new method improves colloidal properties, provides a means by which carboxylate groups are introduced to the surface of the carbon nanoparticles that facilitates the formation of Na-carbon salts when the particles are exposed to the NaClO and NaBr mixed-salt solution. As a metal-salt complex, the Na-carbon is then readily susceptible to dispersion within a polar medium. Vacuum-filtration prepared salted carbon nanotube film, graphene and C60 have high electrical conductivity, and the representative carbon nanotube has a value up to 1.72 × 104 S/m, comparable to that dispersed by other traditional dispersants. Because of its nontoxicity and facile water-based solution features, we expect this dispersion and casting technique would pave its way into more device areas, etc.