Large Scale Synthesis and Light Emitting Fibers of Tailor-Made Graphene Quantum Dots

Abstract

Graphene oxide (GO), which is an oxidized form of graphene, has a mixed structure consisting of graphitic crystallites of sp2 hybridized carbon and amorphous regions. In this work, we present a straightforward route for preparing graphene-based quantum dots (GQDs) by extraction of the crystallites from the amorphous matrix of the GO sheets. GQDs with controlled functionality are readily prepared by varying the reaction temperature, which results in precise tunability of their optical properties. Here, it was concluded that the tunable optical properties of GQDs are a result of the different fraction of chemical functionalities present. The synthesis approach presented in this paper provides an efficient strategy for achieving large-scale production and long-time optical stability of the GQDs, and the hybrid assembly of GQD and polymer has potential applications as photoluminescent fibers or films.

Graphene Flakes in Arc Plasma: Conditions for the Fast Single-Layer Growth

“…The typical growth time was 1 ms, determined from the characteristic velocities (10 -100 m⋅s −1 ) in arc plasma and inter-electrode gap of several mm. Figure 2(d) are the results for the surface temperature changing from 1300 K at the initial time moment (nucleation) down to 1000 K. These two cases conditionally represent the two possible particle (growing flake) trajectories in plasma: the first one corresponds to the flake growing in the hot plasma jet, and the second one corresponds to the flakes which quickly abandon the plasma; as a rule, these particles are deposited onto different areas of the collecting surfaces as demonstrated by our experiments [19]. Apparently, these two cases illustrated the limiting conditions useful to mark the outermost growth conditions and structures; the most quantity of the graphene is growing in the mean conditions.…”

“…The two main process activation energies namely the surface diffusion activation energy ɛ d and carbon evaporation energy ɛ a strongly influence the growth process. Direct measurement of these values is a hard task, thus we used the results of ab initio calculations [30] for ɛ a energy and have verified the most important diffusion activation energy ɛ d by our previous experimental works [19] [23]. The typical growth time was 1 ms, determined from the characteristic velocities (10 -100 m⋅s −1 ) in arc plasma and inter-electrode gap of several mm.…”

“…Plasma-based techniques are the recently developed methods capable of producing the nanoscaled materials with quite different properties [17] [18]. Among others, the arc-discharge method is promising for producing graphene-containing materials in near-industrial scale [19] [20]. The arc-produced graphene flakes usually feature several (up to 5 -10) layers and size up to ten micrometers, which is suitable for nanoelectronic applications [21].…”

Advantages and limitations of nanoparticle labeling for early diagnosis of infection

“…[88,90] To this end, carbon dots have attracted recent attention, and appear to be less toxic and readily modified. [91][92][93] However, these NPs have lower quantum yields (5-60%) as opposed to QDs (10-90%). [89] The early work using QDs was hampered by processes like (1) fluorescence intermittency (blinking); (2) non-radiative Auger recombination of electron-hole pairs; and (3) difficulties in reproducible batch-to-batch synthesis of particles with a consistent size and shape.…”

Investigation on the pH‐independent photoluminescence emission from carbon dots impregnated on polymer matrix

“…Fluorescent carbon nanoparticles (CNPs) with size around 10 nm are generally called carbon dots (C‐dots), which can be synthesized from graphene, carbon nanotubes (CNTs) and other carbon rich materials . This research area has been explored heavily with great excitement because of the high application prospects of these fluorescent nanoparticles in multifaceted areas, extending from optoelectronics, energy conversion and storage to bio‐imaging and sensing .…”