Graphene Quantum Dots Derived from Carbon Fibers

Abstract

Graphene quantum dots (GQDs), which are edge-bound nanometer-size graphene pieces, have fascinating optical and electronic properties. These have been synthesized either by nanolithography or from starting materials such as graphene oxide (GO) by the chemical breakdown of their extended planar structure, both of which are multistep tedious processes. Here, we report that during the acid treatment and chemical exfoliation of traditional pitch-based carbon fibers, that are both cheap and commercially available, the stacked graphitic submicrometer domains of the fibers are easily broken down, leading to the creation of GQDs with different size distribution in scalable amounts. The as-produced GQDs, in the size range of 1-4 nm, show two-dimensional morphology, most of which present zigzag edge structure, and are 1-3 atomic layers thick. The photoluminescence of the GQDs can be tailored through varying the size of the GQDs by changing process parameters. Due to the luminescence stability, nanosecond lifetime, biocompatibility, low toxicity, and high water solubility, these GQDs are demonstrated to be excellent probes for high contrast bioimaging and biosensing applications.

Graphene quantum dots: structural integrity and oxygen functional groups for high sulfur/sulfide utilization in lithium sulfur batteries

“…18,19 Interestingly, GQDs are enriched with oxygen functional groups on their edges, whereby unique properties such as a non-zero bandgap and luminescence on excitation have been reported. [20][21][22] Furthermore, it is expected that GQDs can uniformly cover the target material due to their small size.…”

Graphene-Based Nanomaterials in Bioimaging

“…However, the resonance Raman scattering of SWNTs is determined by the density of states available for the optical transition (e.g. E 11 and E 22 transition), which is dependent on its chirality and diameter (127). Unlike SWNTs, the Raman scattering of graphene and its derivatives is not chirality dependent, and the electronic structure of graphene with a small band gap allows a wide range of photons (visible to NIR) to be used for Raman imaging (12).…”

“…Since its isolation of in 2004, graphene and its derivatives have gained considerable attention in chemistry, materials, physics and biomedical communities (4). Afterwards, the new members of graphene family, such as graphene oxide (GO) (5,6), reduced graphene oxide (rGO) (7,8), graphene quantum dots (GQDs) (9)(10)(11), and their derivatives were extensively explored in biosensors, drug delivery, bioimaging, theranostics, and so on (12)(13)(14)(15)(16).…”

Uniform Graphene Quantum Dots Patterned from Self-Assembled Silica Nanodots

“…Similar to most near-blue emission at a wavelength of around 390 nm in GObased GQDs (size ranges from 3 to 60 nm), our PL properties are comparable to other previous reports. 19,24,29,30,34 This is a significant observation and is helpful to show that the emission wavelength of GQDs results more from oxidation and defects in the sp 2 carbon structure than from the influence of size effects. Although the GQDs in this work were ∼10 nm and ∼20 nm in size, the PL properties must have come from sp 2 clusters of various sizes created by the O 2 plasma treatment, where the dominant domain size of the clusters formed inside the uniform GQDs were ∼3 nm.…”

“…The experimentally shown PL center of the 10 nm GQDs is ∼600 nm. 29 We note that no PL peak was observed from graphene after the PDMS brush treatment and also from the control sample treated with air plasma without BCP patterning ( Figure S5). However, previous studies indicate that the location center of the PL depends on the size of the sp 2 clusters isolated by oxidation or defects, 30,31 even though theoretical studies predict that ∼3-nm-sized GQDs can yield PL emission at ∼390 nm.…”