One-pot synthesis of graphene quantum dots and simultaneous nanostructured self-assembly via a novel microwave-assisted method: impact on triazine removal and efficiency monitoring

Abstract

Graphene quantum dot (GQDs) assemblies from a one-step microwave reaction as bifunctional materials in remediation of triazines.

Recycling Oxacillin Residues from Environmental Waste into Graphene Quantum Dots

“…Absorption features of both GQDs are rather similar (Figure 3) consisting of a continuous UV absorption band associated with the sp 2 -carbon cores that became distended to the visible region derived from both surface defects and core defects linked to the double bonds of carbon and heteroatoms (nitrogen and oxygen). Both unstructured graphitic frameworks are characteristic of other carbon and graphene quantum nanodots previously reported [8,21]. As for most of carbonaceous nanodots [8], the fluorescence mechanism of GQDs is not completely understood.…”

“…The nanosecond decay kinetics are dependent on the excitation wavelengths for both cases. The observation of lifetime values of a few nanoseconds suggested that the fluorescent transitions are dipole-allowed [8,21]. A possible fluorescence mechanism widely applied by most researchers is associated to an excitation-dependent emission behavior owing to multichromophoric moieties within these nanosystems, explaining that the emission is due to the presence of many different surface states while the absorption is due mainly to the core state.…”

“…Graphene quantum dot (GQD) displays exceptional electronic properties accordingly to its laminar structure, size and quantum confinement effect. Many preparation methods of GQDs have been developed until now by both bottom-up and top-down methodologies [3] using a plethora of precursors (recently with attention in biomass substances [15][16][17][18][19] and synthetic conditions with conventional [20] and non-conventional reactors [21,22]). The need for a more rational synthetic procedure for such nanodots with specific optical properties [23] by means of tuning their bandgap from selecting the specific reaction conditions and precursors is therefore desirable to establish a series of relationships between the nanosheet structure and their photophysical features [24,25] according to the effects of internal structure, composition, size and surface.…”

Effect of Halogen Ions on the Photocycle of Fluorescent Carbon Nanodots

“…Beyond their non-toxicity, ease of synthesis, highly functionalized surface, very versatile structural properties [5][6][7][8] and significant two photon absorption properties [9], C-dots usually display an intense fluorescence due to the radiative recombination of an electron with hole after photo-excitation, usually occurring on surface trap sites [1,[10][11][12] although not always [13]. This fluorescence is very sensitive to the external environment and strongly responds to changes in environmental parameters, as for example solvent polarity [10,14], or the presence of molecules or ions in solution [12,[15][16][17], leading to the use of C-dots as sensors in solution phase. Therefore, plenty of optical investigations of the interaction between C-dots and ions or molecules in solution exist in the literature.…”

Temperature-Dependence of Solvent-Induced Stokes Shift and Fluorescence Tunability in Carbon Nanodots

“…In fact, it is well known that the surface of CDs has a key role in the emission mechanism, causing a strong interaction between the dot and, for example, solvent molecules and ions or molecules in solution [15][16][17][18]. One way to investigate these processes arising from the interaction with the external environment is the study of the fluorescence at low temperatures.…”