Mass Production of Graphene Quantum Dots by One‐Pot Synthesis Directly from Graphite in High Yield

Abstract

One of the most efficient and straightforward methods for production of graphene quantum dots (GQDs) could be their direct preparation from graphite powder by one-pot synthesis using high-powered microwave irradiation. It is believed that in this way, graphite can be multiply broken by repeated redox reactions, which leads to a high yield and mass production.

Intramolecular Hydrogen Bonds Quench Photoluminescence and Enhance Photocatalytic Activity of Carbon Nanodots

“…[22] Moreover,t he Ga nd Db ands overlaid on as trongf luorescence background are indicative of defects and functional groups in the CNDs. [23] The relative intensity ratio of Dt oGband (I D /I G )i sc haracteristico ft he degree of disorder in graphitic carbons;t he relative intensity of the CNDs of 0.77 is smaller than those reported previously. [21,24] These results confirmed the well-crystallized sp 2 cores and the partial amorphous nature of the edges of the CNDs, consistentw ith the HRTEM and XRD characterizations.…”

Selective Liquid‐Phase Extraction of Carboxylate‐Rich Graphene Quantum Dots from Graphene Oxide Dispersions

“…Figure 2c shows atomic force microscopy (AFM) topographic images of the CGQDs, indicating that average thickness of the CGQDs is confirmed to be 1.0 AE 0.1 nm, which are in correspondence to previous results. [10] Furthermore, Figure 2d demonstrates the most of the CGQDs consisted of single to tri layers with a height profile mainly within the narrow range of 0.5-3.0 nm with an average height of approximately 1.3 nm; hence, we conclude that the selective liquid-phase extraction via dispersibility controllable co-solvent system is highly effective for obtaining high-crystalline and single-or double layer CGQDs with a narrow size distribution. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 The structural and chemical characterization for pristine GO and CGQDs were implemented using X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy and X-ray diffraction (XRD).…”

“…However, since GO is a nonstoichiometric material, [9] a considerable difficulty exists while controlling both the exact type and surface functionalities during reaction to form GQDs. [10] In order to overcome this obstacle, alternative methods have been devoted using additional oxidation of GO to introduce more oxygen functionalities in GQDs, or the introduction of a cleavage effect through sono-chemical reactions. [11][12][13] However, these are inappropriate due to low carboxylation yield (< 5 wt.%) owing to the random reaction or inertness of the graphitic carbon contents.…”

“…[20] It should be noted that CGQDs with a high fraction of carboxylic acid allow the effective functionalization with other organic components for manipulation of their optical properties. Based on these results, we calculated quantum yields for our samples using Rhodamine B as a reference (QYs = 0.31), [10] the quantum yield (QY) of our samples were 8.34% (CGQDs), 10.92% (rGQDs), and 11.67% (GQDCN), respectively. Interestingly, the QYs of GQDCN shows 1.4 times higher QYs than that of typical CGQDs, which is attributed to the chemical nature of amide bonding with CGQDs.…”

Properties and Synthesis Strategies of Graphene Quantum Dots

“…38 The carbonaceous materials may be carbon fibers, 7 graphene, 30 GO, 39 graphite, 37,[40][41][42][43]44 carbon black, 45 carbon nanotubes, 46,47 coal. 48 Here, we summarize the top-down synthesis of GQDs and the related cutting mechanisms.…”