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Multicolor fluorescence fluorescent graphene quantum dot material preparation method

A technology of graphene quantum dots and fluorescence, which is applied in the direction of luminescent materials, chemical instruments and methods, etc., can solve the problems of cumbersome synthesis steps, weak absorption, and limited applications, and achieve simple process steps, improved dispersion, and high quantum efficiency. Effect

Inactive Publication Date: 2013-09-25
SHANGHAI UNIV
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AI Technical Summary

Problems solved by technology

Although the chemical synthesis of graphene quantum dots has made great progress, the large-scale preparation of high-quality graphene quantum dot fluorescent materials has yet to be developed
On the one hand, the optical properties of currently synthesized graphene quantum dots cannot be compared with traditional semiconductor quantum dots, mainly in: 1) the fluorescence quantum yield of graphene quantum dots is low, most of them are below 10%; 2) All synthesized graphene quantum dots have weak absorption in the visible region, and the first exciton absorption peak falls in the near ultraviolet region
The low fluorescence quantum yield and weak absorption in the visible region lead to very weak fluorescence intensity of quantum dots under visible light excitation, thus limiting the application in bioluminescent imaging, optoelectronic display devices, chemical and biological detection, etc.
On the other hand, there is no breakthrough in the large-scale preparation technology of graphene quantum dots, which is mainly manifested in the low synthesis yield of graphene quantum dots (graphene quantum dots are prone to agglomeration during the preparation process, which makes the material non-dispersible and ineffective. luminescence, etc.), it is still difficult to prepare gram quantities on a laboratory scale, and some synthetic steps are too cumbersome, and even use relatively expensive equipment (PLD, etc.) and auxiliary reagents (such as expensive PEG polymers with amine groups, etc.) Wait
If these problems cannot be solved well, the large-scale application of graphene quantum dots will not be realized

Method used

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  • Multicolor fluorescence fluorescent graphene quantum dot material preparation method
  • Multicolor fluorescence fluorescent graphene quantum dot material preparation method
  • Multicolor fluorescence fluorescent graphene quantum dot material preparation method

Examples

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Effect test

Embodiment 1

[0020] Example 1: Preparation of blue fluorescent graphene quantum dots:

[0021] 1) Weigh 1 g of pyrene, slowly add a mixed acid (1:3) composed of sulfuric acid and nitric acid under stirring, react under reflux for 24-48 hours, and take out after cooling;

[0022] 2). Slowly add the reactant obtained in step a into the ice-water solution, and filter through the filter membrane to remove the acid solution; wash the solid on the filter membrane with distilled water several times until the pH value of the filtrate is about 7.

[0023] 3) Take the solid obtained in step b, ultrasonically disperse the washed chrysanthemum yellow solid in 160 mL of distilled water for 2 h, immediately put it into four 80 mL polytetrafluoroethylene reactors, and add 1 mL of ammonia (25- 28%) and 5 mL hydrazine hydrate at 200 o 24 h at a constant temperature of C.

[0024] 4) Take it out after natural cooling, and filter it with a 25 nm filter membrane. Some black solids remain on the filter me...

Embodiment 2

[0026] Example 2: Preparation of Green Fluorescent Graphene Quantum Dots:

[0027] The preparation steps are the same as 1, the only difference is that the acid oxidation step uses concentrated nitric acid or concentrated nitric acid.

Embodiment 3

[0028] Example 3: Preparation of yellow fluorescent graphene quantum dots:

[0029] The preparation steps are the same as in 2, the only difference is that the medium for the hydrothermal reaction is full ammonia water (4-6 ml).

[0030] The product obtained by the invention can be stably dispersed in water, and is brownish yellow at low concentration, nearly black at high concentration (the higher the concentration, the darker the color), and the concentration range of graphene quantum dots reaches 2.5-3.7 g / L. figure 1 ; The thickness of quantum dots is below 1 nm, and the radial size is mainly distributed below 12 nm, see figure 2 ; The graphene quantum dots obtained by oxidation with concentrated nitric acid emit strong green fluorescence, and the quantum yield reaches 29-32%, and the quantum dots obtained by oxidation with mixed acid emit strong blue fluorescence, and the quantum yield reaches 15% ( Figure 4 ); the yield of quantum dots obtained by oxidation with conce...

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Abstract

The invention relates to a preparation method of multicolor fluorescence fluorescent graphene quantum dots. According to the invention, pyrene with a low price is adopted as a precursor; oxygen functionalization is carried out on the surface of pyrene grains under low temperature; and low-temperature hydrothermal dehydrogenation, growth, and in-situ surface functionalization are carried out under the effect of a catalyst hydrazine and ammonia water. With the method provided by the invention, synthesized quantum dots can be stably dispersed in water. The quantum dots are brown under low concentration, and are approximately black under high concentration (the higher the concentration, the deeper the color). Light emitting color or wavelength is adjustable (blue to yellow, 450-535nm). The quantum dots provided by the invention show attractive application prospects in high-tech fields such as environmental protection, bio-nano technology, new energy, nano-device, and the like. The synthesizing method is simple and environment-friendly, and energy consumption is low. The method is suitable for industrial scale-up.

Description

technical field [0001] The invention relates to a preparation method of a multicolor fluorescent graphene quantum dot material. Background technique [0002] Graphene is made of sp 2 A two-dimensional honeycomb crystal composed of hybridized carbon atoms. Because of its unique structure and properties, graphene material has quickly become the most eye-catching newcomer of carbon materials after carbon nanotubes since it was discovered in 2004. In 2010, the Nobel Prize in Physics was awarded to graphene discoverers to promote this research hotspot. Towards a new climax, high-quality graphene materials and their applications have become another scientific and technological commanding height for scientists from all over the world to compete. At present, the field of graphene is developing towards two poles: one is large-area graphene film materials for microelectronics applications, and the other is ultra-small graphene for nanoelectronics and optoelectronics applications, s...

Claims

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Application Information

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IPC IPC(8): C09K11/65
Inventor 潘登余王亮李珍刘源
Owner SHANGHAI UNIV
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