A reformative oxidation strategy using high concentration nitric acid for enhancing the emission performance of graphene quantum dots

Shao, Taili; Wang, Guodong; An, Xuting; Zhuo, Shujuan; Xia, Yunsheng; Zhu, Changqing

doi:10.1039/c4ra06935h

Cited by 32 publications

(15 citation statements)

References 31 publications

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“…5(c), could also be divided into three symmetrical peaks. The ones located at 530.1 eV and 532.6 eV could be attributed to the lattice oxygen of Zn-O 36 and CQO, 37 while the other one centered at 531.3 eV was assigned to the chemisorbed oxygen because of the surface hydroxyl group. 36 Fig.…”

Section: Resultsmentioning

confidence: 99%

Improving photocatalytic performance of ZnO via synergistic effects of Ag nanoparticles and graphene quantum dots

Wang

Juan

et al. 2015

Phys. Chem. Chem. Phys.

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Herein, we reported a simple and "green" method for preparing the ternary photocatalyst Ag-graphene quantum dots (GQDs)-ZnO. In this method, an aqueous solution of GQDs not only acted as a substituent for the organic solvent for preparing the ZnO precursor but was also used as a reducing agent for the in situ synthesis of Ag nanoparticles (NPs). X-ray diffraction analysis and scanning electron microscopy were employed to confirm the effects of the GQD solution as a solvent on the ZnO structure. Transmission electron microscopy confirmed the synthesis of Ag NPs in the GQD solution as well as the formation of close interconnections between them. Furthermore, photocatalytic tests involving the degradation of Rhodamine B showed that the synthesized ternary photocatalyst displayed excellent visible-light photocatalytic activity, which was much higher than that of pure ZnO and binary photocatalysts such as Ag-ZnO and GQDs-ZnO. We believe that this method will lead to the "green" synthesis of hybrid metal/carbon/semiconductor photocatalysts with higher photocatalytic activities.

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Section: Resultsmentioning

confidence: 99%

Improving photocatalytic performance of ZnO via synergistic effects of Ag nanoparticles and graphene quantum dots

Wang

Juan

et al. 2015

Phys. Chem. Chem. Phys.

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“…The UV absorption spectrum of the three GQDs in Figure 2a exhibits similar characteristic absorption peaks at 230 and 300 nm, the former being due to the π-π* transition of the electrons in the sp 2 carbon conjugate structure, while the latter shoulder around 300 nm is attributed to the n-π* transition of the sp 3 conjugate structure [53,54]. Due to the slight difference in concentration of GQDs prepared by the three electrolytes, the absorption curve will fluctuate up and down.…”

Section: Resultsmentioning

confidence: 92%

Antioxidant Activity of Graphene Quantum Dots Prepared in Different Electrolyte Environments

Zhao

Wang

2019

Nanomaterials

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Antioxidants can reduce or inhibit damage such as oxidative decay caused by elevated levels of free radicals. Therefore, pursuing antioxidants with excellent properties has attracted more and more attention. Graphene quantum dots (GQDs) are considered a promising material because of their good free radical scavenging activity, low toxicity, and excellent water solubility. However, their scavenging efficiency, antioxidant mechanism, and effective control methods need to be improved. Herein, in order to further reveal the antioxidant mechanism of GQDs, the role of electrolytes in improving the antioxidant activity of GQDs is explored. In addition, 1,1-diphenyl-2-picrazine (DPPH∙), hydroxyl (∙OH), and superoxide (∙O2−) free radicals are used to evaluate the antioxidant activity of the as-prepared GQDs. Combined with transmission electron microscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, and cyclic volt–ampere characteristic curves, the effects of an electrolytic environment on the surface functional groups, charge transfer capability, and defect states of GQDs are obtained. The antioxidant mechanism of GQDs and how to improve their antioxidant activity are further elucidated.

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“…The N 1s spectrum (Figure 2C) can be resolved into peaks at 399.9, 401.1, and 406.5 eV, attributed respectively to C–N/N–O, C=N, and N=O. The O 1s spectrum (Figure 2D) consists of three peaks, at 532.2, 532.8, and 533.8 eV, which are assigned to C–O/N–O, C=O/N=O, and C=O, respectively [26,27,28].…”

Section: Resultsmentioning

confidence: 99%

Carbon Nanoparticles Inhibit Α-Glucosidase Activity and Induce a Hypoglycemic Effect in Diabetic Mice

Shao

Yuan

et al. 2019

Molecules

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New, improved therapies to reduce blood glucose are required for treating diabetes mellitus (DM). Here, we investigated the use of a new nanomaterial candidate for DM treatment, carbon nanoparticles (CNPs). CNPs were prepared by carbonization using a polysaccharide from Arctium lappa L. root as the carbon source. The chemical structure and morphology of the CNPs were characterized using Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, elemental analysis, and transmission electron microscopy. CNPs were spherical, 10-20 nm in size, consisting of C, H, O, and N, and featuring various functional groups, including C=O, C=C, C–O, and C–N. In vitro, the as-prepared CNPs could inhibit α-glucosidase with an IC50 value of 0.5677 mg/mL, which is close to that of the reference drug acarbose. Moreover, in vivo hypoglycemic assays revealed that the CNPs significantly reduced fasting blood-glucose levels in mice with diabetes induced by high-fat diet and streptozocin, lowering blood glucose after intragastric administration for 42 days. To the best of our knowledge, this is the first report of CNPs exhibiting α-glucosidase inhibition and a hypoglycemic effect in diabetic mice. These findings suggest the therapeutic potential of CNPs for diabetes.

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A reformative oxidation strategy using high concentration nitric acid for enhancing the emission performance of graphene quantum dots

Abstract: Red fluorescent graphene quantum dots with 18% quantum yield at 600 nm were obtained through a concentrated HNO3oxidation strategy.

Cited by 32 publications

References 31 publications

Improving photocatalytic performance of ZnO via synergistic effects of Ag nanoparticles and graphene quantum dots

Improving photocatalytic performance of ZnO via synergistic effects of Ag nanoparticles and graphene quantum dots

Antioxidant Activity of Graphene Quantum Dots Prepared in Different Electrolyte Environments

Carbon Nanoparticles Inhibit Α-Glucosidase Activity and Induce a Hypoglycemic Effect in Diabetic Mice

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