To lose is to gain: Effective synthesis of water-soluble graphene fluoroxide quantum dots by sacrificing certain fluorine atoms from exfoliated fluorinated graphene

Water-soluble and blue luminescent graphene fluoroxide quantum dots (GFOQDs) with tunable fluorine coverage and size were effectively synthesized from exfoliated fluorinated graphene (FG) by sacrificing certain fluorine to improved solubility and reaction activity. Morphology investigation indicates that the obtained GFOQDs possess narrow size distribution and the average size is 2.5-3.5 nm. Chemical composition analysis confirms that besides C-F covalent bonds, C-O bonds in the forms of hydroxyl and carbonyl co-exist on the structure of GFOQDs. Moreover, photoluminescence performance research considering the surface state and size has also been conducted, and as anticipated in carbon-based quantum dots the GFOQDs exhibit excitation wavelength-dependent properties. Additionally, rather different from other graphene quantum dots (GQDs) that are often susceptible to pH without additional surface passivation, the GFOQDs themselves are poised to resist pH effects and display stable luminescence in both acid and alkali conditions. These results indicate that our method not only opens up a new avenue to prepare GQDs decorated with fluorine and oxygen, but also can find practical applications in novel GQDs-based devices that require water solubility while keep chemical stability and resistance against pH. (C) 2014 Elsevier Ltd. All rights reserved.