Method for preparing yellow or green carbon dots

A carbon dot and green technology, applied in the field of nanomaterials, can solve the problems of difficult preparation of yellow or green carbon dots, high equipment requirements, low quantum yield, etc., and achieve easy large-scale production in factories, green operation, and cheap raw materials Easy to get effect

Active Publication Date: 2018-08-28
SOUTH CENTRAL UNIVERSITY FOR NATIONALITIES
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  • Abstract
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  • Claims
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Problems solved by technology

[0004] For the above defects or improvement needs of the prior art, the object of the present invention is to provide a method for preparing yellow or green carbon dots, wherein through the overall flow process of the preparation method, and the conditions and parameters used in key synthetic reactions (including The types and proportions of reaction raw materials, etc.) are improved, which can effectively solve the problem of difficult preparation of yellow or green carbon dots compared with the prior art. Most of the methods in the prior art prepare blue carbon dots, and only a small part of them prepares The method of yellow or green carbon dots, but these methods have the problems of low quantum yield, complicated operation, and high requirements for equipment. The present invention is based on the synergistic effect of passivating agent and red

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  • Method for preparing yellow or green carbon dots
  • Method for preparing yellow or green carbon dots
  • Method for preparing yellow or green carbon dots

Examples

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Effect test

Embodiment 1

[0046] (1) Dissolve 0.1g of vitamin C, 0.36g of polyethyleneimine (molecular weight: 1800) and 0.5g of citric acid in 20ml of ultrapure water, and stir for 10min under the protection of nitrogen.

[0047] (2) Transfer the mixed solution in step (1) to a hydrothermal reaction kettle, and place it in an electric constant temperature blast drying oven for hydrothermal reaction at 140°C for 50 minutes (before heating, you can use nitrogen or argon or other protective The air in the hydrothermal reaction kettle is discharged), and the green carbon dot solution is obtained.

[0048] (3) Mix the solution in step (2) with methanol at a volume ratio of 1:2, centrifuge at 8000rpm for 10min, remove the supernatant, and freeze-dry to obtain solid carbon dots.

[0049] Rhodamine 6G dissolved in ethanol was used as a reference (quantum yield = 95%). The quantum yield of carbon dots was calculated by comparing the ratio of fluorescence area (excitation wavelength is 420nm) to absorbance. A...

Embodiment 2

[0054] (1) Dissolve 0.8g of vitamin C, 0.18g of polyethyleneimine (molecular weight: 1800) and 0.8g of citric acid in 20ml of ultrapure water, and stir for 10min under the protection of nitrogen.

[0055] (2) Transfer the mixed solution in step (1) to a hydrothermal reaction kettle, and place it in an electric constant temperature blast drying oven for hydrothermal reaction at 150°C for 45 minutes (before heating, you can use nitrogen or argon or other protective The air in the hydrothermal reaction kettle was discharged), and a yellow carbon dot solution was obtained.

[0056] (3) After mixing the solution in step (2) with ethanol at a volume ratio of 1:5, centrifuge at 10,000 rpm for 10 min, remove the supernatant, and freeze-dry to obtain solid carbon dots. figure 2 It is the fluorescence spectrum of the carbon dot synthesized in Example 2. It can be seen from the figure that at the optimal excitation wavelength of 460nm, the emission peak of the carbon dot is located at ...

Embodiment 3

[0058] (1) Dissolve 0.05g of vitamin C, 0.08g of ethylenediamine and 2g of glucose in 20ml of ultrapure water, and stir for 5min under the protection of argon.

[0059] (2) Transfer the mixed solution in step (1) to a microwave reactor, ventilate nitrogen to discharge the air in the reactor and seal the microwave reactor, place it in a microwave digestion and extraction instrument at 180° C. for 5 min, that is A green carbon dot solution was obtained.

[0060] (3) Mix the solution in step (2) with acetonitrile at a volume ratio of 1:4, centrifuge at 10,000 rpm for 8 min, remove the supernatant, and dry in vacuum to obtain solid carbon dots. By calculation, the quantum yield of the carbon dots is 20.3%.

[0061] image 3 The fluorescence spectrum of the carbon dots synthesized for Example 3. It can be seen from the figure that the emission wavelength of the carbon dot is 480nm under the optimal excitation wavelength of 360nm. Under 365nm ultraviolet light, the carbon dots s...

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Abstract

The invention discloses a method for preparing yellow or green carbon dots. The method comprises the following steps: (1) dispersing a carbon source, a passivator and a reducer into ultrapure water, and stirring under the protection of protective gas to obtain a mixed solution; (2) performing heating reaction on the mixed solution obtained in the step (1) in a reaction container to obtain a carbondot solution; and (3) directly placing the carbon dot solution obtained in the step (2) into an ultrafiltration pipe or mixing the carbon dot solution and an organic reagent, and then centrifuging and drying to obtain the solid carbon dots. Based on the synergistic effect of the passivator and the reducer, the green or yellow carbon dots with high quantum yield are further synthesized by a simpleaqueous phase method, the carbon dots with different emitting wavelength can be synthesized by adjusting the mass ratio of the carbon source to the passivator to the reducer, the quantum yield of thegreen carbon dots is 22.5 percent and the quantum yield of the yellow carbon dots is 18.4 percent.

Description

technical field [0001] The invention belongs to the technical field of nanometer materials, and more specifically relates to a method for preparing yellow or green carbon dots. Background technique [0002] Carbon quantum dots (i.e., carbon dots) are a new type of carbon nanomaterials. Compared with traditional semiconductor quantum dots and organic dyes, they have the advantages of low toxicity, good biocompatibility, adjustable luminous range, and easy functionalization. It has broad application prospects in the fields of biomedicine, optoelectronics, catalysis and sensing. There are various methods for preparing carbon dots, but most of the methods synthesized are carbon dots with blue fluorescence. Due to the poor penetration of short-wavelength (blue) carbon dots to tissues, the optical imaging of deep tissues in the body is limited. In addition, almost all biological tissues produce autofluorescence for short-wavelength visible light, which interferes with the imaging...

Claims

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Application Information

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IPC IPC(8): C01B32/15C09K11/65
CPCC09K11/65
Inventor 赵丹韦春锦郝健
Owner SOUTH CENTRAL UNIVERSITY FOR NATIONALITIES
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