Graphene quantum dots (GQDs) are a series of 0-D nanodots consisting of graphene-like derivatives of polycyclic aromatic hydrocarbons. GQDs remain versatile for years in various areas such as biosensing, catalysis and photovoltaics. Many researchers regard GQDs as cheap counterparts in replacing inorganic colloidal quantum dots containing toxic heavy metals (Cd, Pb, etc.). With tunable sizes and optical and electronic properties, GQDs are ideal building-blocks to “bottom-up” construct carbonaceous architectures and patterns in nanoscale through self-assembly. However, only a few work about GQD assemblies are reported so far though there are numerous works for inorganic nanoparticles assemblies. Till now, controllable self-assemblies of GQDs into delicate structures through non-template method especially under mild conditions remains a challenge to materials scientists. GQDs are easily surface-passivated with oxygen-rich functional groups such as carboxyl and hydroxyl, which could be bridged with each other by coordination metal ions. Therefore, metal-organic coordination was applied to be the designed “linking nodes” to construct GQD self-assemblies. Transmission electron microscopy, atomic force microscopy and scanning transmission electron microscopic 3-D tomographic reconstruction technique were used to study the morphology of the assemblies. By the use of different types of metal ions as well as solvents with various dielectric constant, 1-D nanoribbons and non-integer dimensional nanofractals were fabricated. Furthermore, the length and width of the nanoribbons, the size and the fractal dimensionality of nanofractals could be controlled by adjusting the concentration of metal ions and pH value of the solution. The nanoribbons and nanofractals showed quite different optical and electronic properties comparing with dispersed GQDs, reflecting in UV-vis and fluorescent spectra, Raman spectra, and magnetic circular dichroism, etc. GQD nanoribbons and nanofractals will give out great potential in various applications such as optical and electronic devices, photochemical catalysis and enzyme mimics.

Nanoribbons and nanofractals self-assembled from graphene quantum dots

253rd National Meeting (2017)

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