Nitrogen-doped Graphene Quantum Research Articles

Efficient green light-based photocatalytic removal of bilirubin by a biocompatible nanocomposite of nitrogen doped graphene quantum dots/Au

Nitrogen-doped graphene quantum dots/Au (NGQDs/Au) nanocomposite was synthesized by hydrothermal method followed by a photochemical route. The gram-scale nitrogen-doped graphene quantum dot was synthesized by using hydrothermal method from urea and citric acid as a precursor. By adding HAuCl4 to the prepared sample, the nitrogen-doped graphene quantum dots/Au nanocomposite was made in a straightforward photochemical process. The synthesized composite was utilized directly as a biocompatible photocatalyst for bilirubin degradation under green light irradiation.The nanocomposite was characterized using FESEM, Raman, XRD, TEM, UV–Vis spectroscopy, and PL. The quantum yield of the nanocomposite was calculated. The role of surface plasmon resonance (SPR) of Au nanoparticles in reduction of the quantum yield and quantum yield effect on the photodegradation process was investigated. The photocatalytic degradation efficiency of bilirubin in presence of the synthesized nanocomposite was measured to be nearly 74.7 % after 100 min green light irradiation, which is 5 times more than blue light used in clinical phototherapy without any photocatalyst. The optical analysis results reveal that the doping of nitrogen in GQDs and compositing with gold could accelerate the suppression of charge carrier's recombination. The future application of biocompatible photocatalysts in jaundice treatment under the green light irradiation was also approved in this research.

Visible light-assisted photocatalytic degradation of organic contaminants using nitrogen-doped graphene quantum dots@MnCo2O4 nanocomposite

Visible light-assisted photocatalytic degradation of organic contaminants using nitrogen-doped graphene quantum dots@MnCo2O4 nanocomposite

Nanocoating on cotton fabric with nitrogen-doped graphene quantum dots/titanium dioxide/PVA: an erythemal UV protection and photoluminescent finishing

Prolonged exposure to ultraviolet (UV) radiation from the sun can result in several skin problems, such as accelerating aging, burns, blemishes, or even cancer. Even when wearing clothes, there is still a risk that the user will be exposed to UV radiation and suffer skin damage. Therefore, it is necessary to apply anti-UV treatments to the clothes and fabrics used, so that users become safe. Nitrogen doped graphene quantum dots (N-GQD) and titanium dioxide (TiO2) NPs are materials that have a broad spectrum of UV absorption and are promising candidates to be applied in functional finishing in use on textile materials, giving textiles property anti-UV. The aim of this research is to evaluate the synergy effect between N-GQD and TiO2 NPs in getting a nanocoating that can be applied on a cotton fabric, add photoluminescent and anti-UV properties. The nanocoatings obtained were applied via industrial discontinuous method, the high-pressure and high-temperature exhaustion process to the cotton fabric using polyvinyl alcohol as a binding agent. According to the UV protection assessment, it was observed that both materials are excellent UV absorbers and their ultraviolet protection factor (UPF) are highly dependent on the concentrations used in the nanocoated cotton fabrics. Thus, nanocoated cotton with TiO2, N-GQD and TiO2/N-GQD revealed an UPF of +50, which established their effectiveness in protecting against UV radiation. They also withstand up to 20 wash cycles with no change in UPF.

Sulfur and nitrogen-doped graphene quantum dots/PANI nanocomposites for supercapacitors

Sulfur and nitrogen-doped graphene quantum dots/polyaniline nanocomposites were synthesized and their electrochemical charge storage properties were tested for supercapacitor applications.

Dual-emission ratio fluorescence detection of bleomycin based on nitrogen doped graphene quantum dots@gold nanoclusters assembly

Herein, a dual-emission ratio fluorescence probe for copper ions (Cu2+)-based bleomycin (BLM) detection was established for the first time. The ratio fluorescence probe, nitrogen doped graphene quantum dots@gold nanoclusters (NGQDs@AuNCs), showed two well-resolved emission peaks at 440 nm and 580 nm respectively. Fluorescence intensity of AuNCs at 580 nm can be quenched by Cu2+ but restored in the presence of BLM, while fluorescence intensity of NGQDs at 440 nm remained unchanged throughout the process. The Cu2+-triggered fluorescence quenching can be attributed to aggregation-induced quenching mechanism, and the strong affinity between Cu2+ and BLM can make the quenched fluorescence turn on. Under optimal conditions, the BLM can be detected in the range of 0.8–1800 nM and the limit of detection (LOD) was 0.27 nM. Furthermore, the established method in the application of human serum samples has been confirmed.

Fluorescence detection of cholesterol using a nitrogen-doped graphene quantum dot/chromium picolinate complex-based sensor.

Nitrogen-doped graphene quantum dots (N-GQDs), with superior biocompatibility, strong resistance to photobleaching and convenient surface grafting, have sparked a surge of related-bio applications. In this study, combined with chromium picolinate (CrPic), N-GQDs synthesized by a facile hydrothermal approach are used to construct an environmentally-friendly sensor for the detection of cholesterol by exploiting the fluorescence enhancement of N-GQDs/CrPic. Herein, CrPic is grafted on N-GQDs via the linker of cysteamine (Cys), and the fluorescence of the N-GQDs is quenched by photoinduced electron transfer (PET), wherein CrPic functions as an electron donating group and the N-GQDs serves as an electron accepting group. Besides, cholesterol is stimulated to form a favourable complex with N-GQDs/CrPic because CrPic also acts as a potential receptor for cholesterol by strong affinity and π-π interaction, and the fluorescence of N-GQDs/CrPic is enhanced indicating that cholesterol could impede electron transfer from CrPic to the N-GQDs. This N-GQDs/CrPic-based sensor has been successfully applied to selectively determine the concentration of cholesterol with a linear range of 0-520 μM and a limit of detection (LOD) of 0.4 μM. Meanwhile, this present sensing strategy in human serum has acceptable practicability, reproducibility and precision.

Boron- and nitrogen-doped graphene quantum dots/graphene hybrid nanoplatelets as efficient electrocatalysts for oxygen reduction.

The scarcity and high cost of platinum-based electrocatalysts for the oxygen reduction reaction (ORR) has limited the commercial and scalable use of fuel cells. Heteroatom-doped nanocarbon materials have been demonstrated to be efficient alternative catalysts for ORR. Here, graphene quantum dots, synthesized from inexpensive and earth-abundant anthracite coal, were self-assembled on graphene by hydrothermal treatment to form hybrid nanoplatelets that were then codoped with nitrogen and boron by high-temperature annealing. This hybrid material combined the advantages of both components, such as abundant edges and doping sites, high electrical conductivity, and high surface area, which makes the resulting materials excellent oxygen reduction electrocatalysts with activity even higher than that of commercial Pt/C in alkaline media.