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Nano-crystal with core-shell structure and preparation method thereof

A core-shell structure, nanocrystalline technology, applied in the field of nanomaterials, can solve the problems of semiconductor nanoparticles losing practical application value, not revealing relevant data or maps, unable to know cadmium sulfide quantum dots, etc., to avoid toxicity and high cost. , The effect of good fluorescence emission peak shape and easy operation

Inactive Publication Date: 2010-06-02
HENAN UNIV OF SCI & TECH
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  • Abstract
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Problems solved by technology

However, this method also has unavoidable shortcomings: ① It is impossible to prepare quantum dots with core-shell structure by simple steps, and the surface of quantum dots prepared by metal-organic method is often covered with an organic layer, such as TOPO (trioctylphosphine oxide, extremely toxic and expensive) This has lost many options for possible optimal development of the subsequent surface modification of quantum dots; ②The metal-organic method is not only toxic, flammable, but also extremely expensive in raw materials, so it is greatly limited in practical applications
As resolvable bioluminescent quantum dots, semiconductor nanoparticles prepared by water method have lost their practical application value
In addition, it has been reported that the hydrothermal synthesis method (abbreviated as the hydrothermal method) uses water as a solvent in a closed device (autoclave), and reacts under high pressure and temperature rise conditions to prepare a 5nm size (calculated by the Scherrer formula XRD diffraction peak half-peak width), spherical cubic β-CdS nanocrystals with unit cell parameter a=0.5818nm (see: Su Yi et al.: Hydrothermal Synthesis and Characterization of Nano ZnS and CdS, "Applied Chemistry", 1996, 13:56) , but did not reveal the relevant data or spectra of the fluorescence emission properties of the CdS nanocrystals, and it is impossible to know whether it is a cadmium sulfide quantum dot with fluorescence emission properties

Method used

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  • Nano-crystal with core-shell structure and preparation method thereof
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  • Nano-crystal with core-shell structure and preparation method thereof

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Effect test

Embodiment 1

[0027] Measure 0.05 (mol / L) cadmium acetate 60ml and 0.05 (mol / L) L-cysteine ​​50ml according to the ratio of 1.2 and mix them in the autoclave liner (the concentration of cadmium acetate in the reaction system is 27mmol / L, the reaction concentration of L-cysteine ​​is 22.5mmol / L), and be 1mol / L potassium hydroxide solution to regulate the acidity and alkalinity of solution with concentration, make it pH be 11. The autoclave was sealed, heated and pressurized to 130° C., and magnetically stirred. The high temperature stage is kept warm for 7 hours. After cooling down naturally and ensuring that the pressure in the autoclave drops to normal pressure, open the lid of the autoclave, transfer the materials in the autoclave to a ground bottle, and store in the dark. Obtained product characterization data: atomic force microscope (AFM) photos and fluorescence emission spectra are shown in figure 2 As shown, the size of the cadmium sulfide quantum dot is about 6.6nm, the λmax is ...

Embodiment 2

[0029] Measure 70ml of 0.05 (mol / L) cadmium acetate and 50ml of 0.05 (mol / L) L-cysteine ​​according to the ratio of Cd / S of 1.4 and mix them in the liner of the autoclave (the concentration of cadmium acetate in the reaction system is 27.2 mmol / L, the reaction concentration of L-cysteine ​​is 22.7mmol / L), and with a concentration of 1mol / L potassium hydroxide solution, the pH is adjusted to be 10. The autoclave was sealed, heated and pressurized to 110° C., and magnetically stirred. Keep warm for 5 hours in the high temperature stage. After cooling down naturally and ensuring that the pressure in the autoclave drops to normal pressure, open the lid of the autoclave, transfer the materials in the autoclave to a ground bottle, and store in the dark. Its X-ray powder crystal diffraction (XRD) pattern is as follows figure 1 As shown, two sets of crystal parameters are found in the figure: the XRD spectrum of the hexagonal structure of cadmium cadmium (Greenockite) and the XRD sp...

Embodiment 3

[0031] Measure 0.1 (mol / L) cadmium acetate 65ml and 0.1 (mol / L) L-cysteine ​​50ml according to the ratio of 1.3 and mix them in the autoclave liner (the concentration of cadmium acetate in the reaction system is 54mol / L, the reaction concentration of L-cysteine ​​is 45mmol / L), and be 12 with concentration be 1mol / L potassium hydroxide solution regulation solution pH. The autoclave was sealed, heated to 130° C. with magnetic stirring, and kept warm for 6 hours. After cooling down naturally and ensuring that the pressure in the autoclave drops to normal pressure, open the lid of the autoclave, transfer the materials in the autoclave to a ground bottle, and store in the dark. Its fluorescence excitation and emission spectra are shown in Figure 4 .

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Abstract

The invention discloses a nanocrystalline with core-shell structure. The nanocrystalline is of a core-shell structure and takes cadmium sulphide as a core and cadmium carbonate as a peripheral shell.A process for preparing the nanocrystalline is that the mol ratio of water-soluble cadmium acetate and sulfur source Cd / S is x, whichin 1.1<=x<=1.4, and raw materials are placed in a high-pressure autoclave to react under the condition that reaction system is of pH 9 to 13, wherein the concentration of the water-soluble cadmium acetate in the reaction system is 5 to 54.5 mmol / L, and the concentration of the sulfur source is 4.5 to 50 mmol / L. The invention is simple in process, easy in operation and low in price, further, the prepared nanocrytalline which is of cadmium sulphide or cadmium carbonate core-shell structure is prepared and the particle diameter of the nanocrytalline is -5nm. The invention has the advantages of high chemical stability, good fluorescence-emission monochromaticity,relatively narrow peak width at half height and the like in comparison with an existing nude nanocrystalline product, which saves precious placing time for surface finish of the nanocrystalline and improves fluorescent property, thereby enabling the nanocrystalline to be used as biological tissue marks after subsequent treatment such as the surface finish and the like.

Description

technical field [0001] The invention relates to the field of nanomaterials, in particular to a nanocrystal with a core-shell structure and a preparation method thereof. Background technique [0002] Quantum dots (quantum dots, QDs) can also be called semiconductor nanocrystals (semiconductor nanocrystals), as a new type of fluorescent material, compared with traditional organic dye molecules, quantum dots do have many advantages. One of the biggest advantages is that there are rich colors. Different types of nano-semiconductor materials can produce a family of markers with different emission wavelengths and distinct colors according to the size change, which is impossible for dye molecules. In addition, it has a wide excitation spectrum and continuous distribution, while the emission spectrum has good monochromaticity, and the color is adjustable, and it can withstand multiple excitations and light emissions, and has long-lasting stability. The surface of quantum dots is m...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C09K11/56B81B1/00B82B3/00
Inventor 许荣辉文九巴赵胜利李谦李洛利
Owner HENAN UNIV OF SCI & TECH
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