CN110563023A

CN110563023A - high-fluorescence-brightness ZnO quantum dot and preparation method thereof

Info

Publication number: CN110563023A
Application number: CN201910896742.XA
Authority: CN
Inventors: 吕斌; 余亚金; 郭旭; 高党鸽; 马建中
Original assignee: Shaanxi University of Science and Technology
Current assignee: Shaanxi University of Science and Technology
Priority date: 2019-09-23
Filing date: 2019-09-23
Publication date: 2019-12-13

Abstract

The invention discloses a high fluorescence brightness ZnO quantum dot and a preparation method thereof, and the technical scheme is as follows: dissolving zinc nitrate dihydrate in a methanol solvent to obtain a zinc nitrate methanol solution; dissolving potassium hydroxide in a methanol solvent to obtain a potassium hydroxide methanol solution; and slowly dripping the potassium hydroxide methanol solution into the zinc nitrate methanol solution, reacting for a period of time after dripping is finished, adding tetraethoxysilane to passivate and stabilize the ZnO quantum dots, then adding a small amount of distilled water to react mildly, and separating and purifying to obtain white ZnO quantum dot powder. The invention is based on cheap and easily available zinc nitrate dihydrate and potassium hydroxide as raw materials, and the prepared ZnO quantum dots are bright yellow under an ultraviolet lamp, have the advantages of good stability, high fluorescence brightness, good water solubility, safety, no toxicity and environmental friendliness, and are environment-friendly and excellent in performance.

Description

high-fluorescence-brightness ZnO quantum dot and preparation method thereof

Technical Field

The invention relates to a ZnO quantum dot and a preparation method thereof, in particular to a high-fluorescence-brightness ZnO quantum dot and a preparation method thereof.

background

The ZnO quantum dot is a wide-bandgap oxide semiconductor material with a direct band gap, the relative proportion of the number of surface atoms and the surface energy of the ZnO quantum dot are increased along with the reduction of the particle size, and the movement of carriers (electrons, holes and excitons) in the ZnO quantum dot in each direction becomes more complicated due to the fact that the ZnO quantum dot is restrained to be stronger, so that the ZnO quantum dot has special properties which are not possessed by a macroscopic material system, such as a surface effect, a quantum size effect, a small size effect, a dielectric confinement effect and a quantum tunneling effect.

Compared with ZnO as a bulk material, the ZnO quantum dots have smaller particle size, and the specific surface area of the ZnO quantum dots is rapidly increased along with the reduction of the particle size, so that the ZnO quantum dots are easy to agglomerate. Therefore, obtaining high-stability ZnO quantum dots on the basis of requirements of mature preparation process, simple purification and separation process and excellent performance has become a research focus of researchers.

disclosure of Invention

The invention aims to provide a ZnO quantum dot with high fluorescence brightness and a preparation method thereof, and the prepared ZnO quantum dot has excellent performance, is safe and nontoxic, is environment-friendly and has a mature synthesis process.

In order to achieve the purpose, the invention provides a preparation method of high-fluorescence brightness ZnO quantum dots, which comprises the following steps:

dissolving 0.87 mass part of zinc acetate dihydrate in 31.30 mass parts of methanol, fully stirring for 20min to obtain a zinc acetate methanol solution, dissolving 5.21 ~ 6.08 mass parts of potassium hydroxide in 62.60 mass parts of methanol, ultrasonically dispersing uniformly to obtain a potassium hydroxide methanol solution, dropwise adding the potassium hydroxide methanol solution into the zinc acetate methanol solution, raising the temperature to 25 ~ 40 ℃, reacting for 1 h, dropwise adding 0.37 mass part of ethyl orthosilicate, dropwise adding 0.79 mass part of distilled water, continuously stirring for 20min, and finally drying in a 60 ℃ oven to obtain ZnO quantum dot white powder.

The stirring conditions of the zinc acetate methanol solution are as follows: normal temperature and rotation speed of 300 r/min.

the rotating speed of the potassium hydroxide methanol solution is required to be increased to 600 r/min before dripping, the speed is controlled to be 1 ~ 2 drops/second during dripping, and the system is changed into light blue emulsion from colorless and transparent.

The specific steps of the separation and purification are as follows: after centrifugation, the supernatant was decanted to obtain a white precipitate, which was then washed 3 times with methanol.

The ZnO quantum dot with high fluorescence brightness is prepared by the preparation method.

Compared with the prior art, the invention has the beneficial effects that:

The ZnO quantum dots prepared by passivating with tetraethoxysilane have good stability and high fluorescence brightness, and are environment-friendly materials with excellent performance; the invention takes zinc acetate dihydrate and potassium hydroxide as raw materials, has lower cost, mature synthesis process, safety, no toxicity and environmental protection.

Drawings

FIG. 1 is a graph showing the change in fluorescence intensity of ZnO quantum dots before and after passivation;

FIG. 2 is a graph showing the change of fluorescence intensity of ZnO quantum dots after being left for one month after passivation.

Detailed Description

The present invention will be described in further detail with reference to specific examples, but the embodiments of the present invention include, but are not limited to, the scope shown in the following examples.

Example 1:

dissolving 0.87 mass part of zinc acetate dihydrate in 31.30 mass parts of methanol, fully stirring for 20min at normal temperature, rotating at 300 r/min to obtain a zinc acetate methanol solution, dissolving 5.21 mass parts of potassium hydroxide in 62.60 mass parts of methanol, ultrasonically dispersing uniformly to obtain a potassium hydroxide methanol solution, increasing the rotating speed to 600 r/min, dropwise adding the potassium hydroxide methanol solution into the zinc acetate methanol solution, controlling the speed to be 1 ~ 2 drops/second, converting the colorless transparent solution into light blue emulsion, then increasing the temperature to 25 ℃, reacting for 1 h, dropwise adding 0.37 mass part of ethyl orthosilicate after the reaction is finished, dropwise adding 0.79 mass part of distilled water, continuously stirring for 20min, finally centrifuging, pouring out the supernatant to obtain a white precipitate, washing for 3 times with methanol, and drying in a 60 ℃ oven to obtain the ZnO quantum dot white powder with high fluorescence brightness.

Example 2:

dissolving 0.87 mass part of zinc acetate dihydrate in 31.30 mass parts of methanol, fully stirring for 20min at normal temperature, rotating at 300 r/min to obtain a zinc acetate methanol solution, dissolving 5.21 mass parts of potassium hydroxide in 62.60 mass parts of methanol, ultrasonically dispersing uniformly to obtain a potassium hydroxide methanol solution, increasing the rotating speed to 600 r/min, dropwise adding the potassium hydroxide methanol solution into the zinc acetate methanol solution, controlling the speed to be 1 ~ 2 drops/second, converting the colorless transparent solution into light blue emulsion, then increasing the temperature to 30 ℃, reacting for 1 h, dropwise adding 0.37 mass part of ethyl orthosilicate after the reaction is finished, dropwise adding 0.79 mass part of distilled water, continuously stirring for 20min, finally centrifuging, pouring out the supernatant to obtain a white precipitate, washing for 3 times with methanol, and drying in a 60 ℃ oven to obtain the ZnO quantum dot white powder with high fluorescence brightness.

example 3:

dissolving 0.87 mass part of zinc acetate dihydrate in 31.30 mass parts of methanol, fully stirring for 20min at normal temperature, rotating at 300 r/min to obtain a zinc acetate methanol solution, dissolving 5.21 mass parts of potassium hydroxide in 62.60 mass parts of methanol, ultrasonically dispersing uniformly to obtain a potassium hydroxide methanol solution, increasing the rotating speed to 600 r/min, dropwise adding the potassium hydroxide methanol solution into the zinc acetate methanol solution, controlling the speed to be 1 ~ 2 drops/second, converting the colorless transparent solution into light blue emulsion, then increasing the temperature to 40 ℃, reacting for 1 h, dropwise adding 0.37 mass part of ethyl orthosilicate after the reaction is finished, dropwise adding 0.79 mass part of distilled water, continuously stirring for 20min, finally centrifuging, pouring out the supernatant to obtain a white precipitate, washing for 3 times with methanol, and drying in a 60 ℃ oven to obtain the ZnO quantum dot white powder with high fluorescence brightness.

example 4:

dissolving 0.87 mass part of zinc acetate dihydrate in 31.30 mass parts of methanol, fully stirring for 20min at normal temperature, rotating at 300 r/min to obtain a zinc acetate methanol solution, dissolving 6.08 mass parts of potassium hydroxide in 62.60 mass parts of methanol, ultrasonically dispersing uniformly to obtain a potassium hydroxide methanol solution, increasing the rotating speed to 600 r/min, dropwise adding the potassium hydroxide methanol solution into the zinc acetate methanol solution, controlling the speed to be 1 ~ 2 drops/second, converting the colorless transparent solution into light blue emulsion, then increasing the temperature to 25 ℃, reacting for 1 h, dropwise adding 0.37 mass part of ethyl orthosilicate after the reaction is finished, dropwise adding 0.79 mass part of distilled water, continuously stirring for 20min, finally centrifuging, pouring out the supernatant to obtain a white precipitate, washing for 3 times with methanol, and drying in a 60 ℃ oven to obtain the ZnO quantum dot white powder with high fluorescence brightness.

Example 5:

dissolving 0.87 mass part of zinc acetate dihydrate in 31.30 mass parts of methanol, fully stirring for 20min at normal temperature, rotating at 300 r/min to obtain a zinc acetate methanol solution, dissolving 6.08 mass parts of potassium hydroxide in 62.60 mass parts of methanol, ultrasonically dispersing uniformly to obtain a potassium hydroxide methanol solution, increasing the rotating speed to 600 r/min, dropwise adding the potassium hydroxide methanol solution into the zinc acetate methanol solution, controlling the speed to be 1 ~ 2 drops/second, converting the colorless transparent solution into light blue emulsion, then increasing the temperature to 30 ℃, reacting for 1 h, dropwise adding 0.37 mass part of ethyl orthosilicate after the reaction is finished, dropwise adding 0.79 mass part of distilled water, continuously stirring for 20min, finally centrifuging, pouring out the supernatant to obtain a white precipitate, washing for 3 times with methanol, and drying in a 60 ℃ oven to obtain the ZnO quantum dot white powder with high fluorescence brightness.

In the above examples, example 1 is the most preferred example.

FIG. 1 is a fluorescence intensity spectrum of ZnO quantum dots before and after passivation of tetraethoxysilane prepared in example 1. As is apparent from fig. 1, the fluorescence intensity of the passivated ZnO quantum dots is increased by 2 orders of magnitude compared to that before the passivation, and the fluorescence intensity curve of the passivated ZnO quantum dots is smoother, which indicates that the fluorescence intensity of the passivated ZnO quantum dots is significantly increased. Therefore, the passivated quantum dots have higher stability.

Fig. 2 is a graph of fluorescence intensity spectra of ZnO quantum dots before and after passivation after being left for one month as prepared in example 1. As is apparent from FIG. 2, the change amplitude of the fluorescence intensity of the passivated ZnO quantum dots after being placed for one month is small. Therefore, the passivated ZnO quantum dots have higher stability.

The invention is not limited to the examples, and any equivalent changes to the technical solution of the invention by a person skilled in the art after reading the description of the invention are covered by the claims of the invention.

Claims

1. A preparation method of high fluorescence brightness ZnO quantum dots is characterized by comprising the following steps:

2. the method for preparing ZnO quantum dots with high fluorescence brightness according to claim 1, wherein the method comprises the following steps:

3. The method for preparing ZnO quantum dots with high fluorescence brightness according to claim 2, wherein the method comprises the following steps:

the rotation speed of the potassium hydroxide methanol solution must be increased to 600 r/min before dripping, the speed is controlled to be 1 ~ 2 drops/second during dripping, and the system is changed into light blue emulsion from colorless and transparent.

4. The method for preparing ZnO quantum dots with high fluorescence brightness according to claim 3, wherein the method comprises the following steps:

The specific steps of separation and purification are as follows: after centrifugation, the supernatant was decanted to obtain a white precipitate, which was then washed 3 times with methanol.

5. A ZnO quantum dot with high fluorescence luminance obtained by the production method according to claims 1 to 4.