CN110092359B

CN110092359B - Method for preparing vanadium diselenide quantum dots through liquid phase stripping

Info

Publication number: CN110092359B
Application number: CN201910443897.8A
Authority: CN
Inventors: 吴幸; 王超伦
Original assignee: East China Normal University
Current assignee: East China Normal University
Priority date: 2019-05-27
Filing date: 2019-05-27
Publication date: 2022-08-09
Anticipated expiration: 2039-05-27
Also published as: CN110092359A

Abstract

The invention discloses a method for preparing vanadium diselenide quantum dots by liquid phase stripping, which comprises the steps of stripping metallic vanadium diselenide powder by using a formamide organic solvent, adding a proper amount of formamide into the vanadium diselenide powder, pre-stripping by using an ultrasonic instrument and crushing the vanadium diselenide powder by using a probe type ultrasonic cell crusher, and then centrifugally collecting and purifying the vanadium diselenide quantum dots. In the preparation process, an ice-water mixed bath is adopted to stabilize the temperature of the ultrasonic solution to be near zero, so that the quantum dots are prevented from agglomerating. The surface tension of formamide is close to the surface energy of vanadium diselenide, so that the vanadium diselenide can be efficiently stripped to obtain the quantum dot. Another advantage of using formamide is that the prepared vanadium diselenide quantum dots can be stably present in formamide for a long time. The method can realize the efficient preparation of a large amount of metallic vanadium diselenide quantum dots with uniform size, and has wide application prospect in the fields of biological detection and photoelectron.

Description

Method for preparing vanadium diselenide quantum dots through liquid phase stripping

Technical Field

The invention relates to the field of preparation of quantum dot nano materials, in particular to a method for preparing vanadium diselenide quantum dots by liquid phase stripping.

Background

The two-dimensional material has abundant electrical properties, and the electrical conductivity of the two-dimensional material comprises insulators, semiconductors, semimetals and metals. Has wide application in the fields of electronics, energy, catalysis and the like. The metallic vanadium diselenide quantum dots have potential application value in the fields of metal enhanced fluorescence biological probes, photoelectrons and the like.

The interaction force between layers of the vanadium diselenide with the two-dimensional layered structure is weak, and belongs to van der Waals force. The interlayer has no chemical or ionic bonding, so the interlayer spacing is larger, other ions or molecules can be accommodated, and the interlayer can be dissociated into a monolayer or few-layer structure under the action of external mechanical vibration. Under the continuous action of external mechanical vibration, a single layer or a few layers of vanadium diselenide are continuously crushed to finally form the vanadium diselenide quantum dots. The selection of a proper intercalation solvent in the preparation process of the vanadium diselenide quantum dots is very important. The yield of quantum dots is highest when the surface tension of the solvent is close to the surface energy of vanadium diselenide. And an ice-water mixed bath is also needed for the organic solvent, the heat generated in the ultrasonic process is absorbed, the temperature of the ultrasonic solution is constant, the change of the properties of the organic solvent is prevented, and the vanadium diselenide quantum dots are agglomerated at high temperature.

Most of reported organic solvents for preparing quantum dots are N-methyl pyrrolidone (NMP), but the organic solvents are not suitable for efficiently preparing vanadium diselenide quantum dots. Therefore, the exploration of novel organic solvents for preparing vanadium diselenide quantum dots becomes a key problem which needs to be solved urgently. In addition, the reported two-dimensional material quantum dots are all semiconductor or semi-metallic, and no relevant report is provided about the preparation of the metallic vanadium diselenide quantum dots.

Disclosure of Invention

The invention aims to provide a method for preparing vanadium diselenide quantum dots by liquid phase stripping. The method can be used for efficiently and stably preparing the vanadium diselenide quantum dots.

The specific technical scheme for realizing the purpose of the invention is as follows:

a method for preparing vanadium diselenide quantum dots by liquid phase stripping comprises the following specific steps:

step 1: grinding the massive crystal of vanadium diselenide into particles with the size of 0.1-0.01 mm by using a mortar;

step 2: filling the crushed vanadium diselenide into a glass container, and adding analytically pure formamide into the glass container, wherein the preparation concentration is 20-100 mg/ml, and the liquid level height range of the formamide is 2-10 cm;

and step 3: and (3) putting the prepared vanadium diselenide/formamide mixed solution into an ultrasonic instrument with ice water mixed bath for pre-ultrasonic treatment for 2-5 hours.

And 4, step 4: and further crushing the pre-sonicated vanadium diselenide/formamide mixed solution by using a probe type ultrasonic cell crusher. The probe extended into the solution level by a distance of 1 cm. The crushing power of the ultrasonic cell crusher is 60-100 watts, the working cycle of the ultrasonic probe is 1-5 seconds of working and 1-4 seconds of stopping, and the total crushing time is 2-5 hours. The whole ultrasonic process adopts an ice-water mixed bath.

And 5: and putting the vanadium diselenide/formamide mixed solution crushed by the probe type cell crusher into a centrifugal tube, and centrifuging in a centrifugal machine. The centrifugal rotating speed is 6000-8000 rpm, and the centrifugal time is 20-40 minutes.

Step 6: and collecting the centrifuged supernatant to obtain the vanadium diselenide quantum dots dispersed in the formamide.

The invention has the beneficial effects that:

(1) compared with a common NMP organic solvent, the method has the advantages that the method for dispersing vanadium diselenide by formamide is more efficient, and the obtained quantum dots are small in size dispersion degree and complete in crystal structure.

(2) The preparation process is simple, and the used formamide is more environment-friendly.

(3) The ice-water mixed bath can ensure the stability of the organic solvent in the preparation process of the vanadium diselenide quantum dots and prevent the spontaneous agglomeration of the vanadium diselenide quantum dots at high temperature.

Drawings

FIG. 1 is a schematic illustration of the preparation of a quantum dot sample;

FIG. 2 is a high resolution image of a high resolution transmission electron microscope of a quantum dot sample;

FIG. 3 is a Raman spectrum of a quantum dot sample;

in the figure: 1-VSe ₂ The method comprises the following steps of preparing powder, 2-formamide, a 3-ultrasonic instrument, a 4-ice water mixture, a 5-glass container, 6-vanadium diselenide/formamide mixed liquor obtained after ultrasonic treatment by a cell crusher, 7-an ultrasonic probe of the cell crusher, 8-vanadium diselenide quantum dot/formamide mixed liquor and 9-a centrifugal tube.

Detailed Description

The present invention will be further described with reference to the following drawings and examples, which are not intended to limit the scope of the present invention. The present invention can be modified and implemented as appropriate within the scope of the main claim.

Example 1

Step 1: bulk crystals of vanadium diselenide were crushed into particles of size 0.05 mm by mortar grinding.

Step 2: the crushed 500 mg of vanadium diselenide is filled into a glass container, 10 ml of formamide is added into the glass container, the preparation concentration is 50 mg/ml, and the liquid level height of the formamide is not lower than 2 cm.

And step 3: the prepared vanadium diselenide/formamide mixture is put in an ultrasonic instrument of an ice-water mixed bath for pre-ultrasonic treatment for 3 hours.

And 4, step 4: and further crushing the pre-sonicated vanadium diselenide/formamide mixture by using a probe type ultrasonic cell crusher. The probe extended into the solution level by a distance of 1 cm. The crushing power of the ultrasonic cell crusher is 80 watts, the working cycle of the ultrasonic probe is 2 seconds of work, 2 seconds of stop, and the total crushing time is 4 hours. The whole ultrasonic process adopts an ice-water mixed bath.

And 5: and (3) putting the vanadium diselenide solution crushed by the probe type cell crusher into a centrifugal tube, and centrifuging in a centrifugal machine. The centrifugation speed was 7000 rpm and the centrifugation time was 30 minutes.

And (3) placing the collected metallic vanadium diselenide quantum dots into a transmission electron microscope for observation, wherein the vanadium diselenide quantum dots in the high-resolution transmission electron microscope image are circular or elliptical, and the sizes of the vanadium diselenide quantum dots are distributed near 5 nanometers, as shown in figure 2. VSe in FIG. 3 ₂ Raman Spectroscopy of Quantum dots, VSe ₂ The Raman shift of the quantum dots is 205.5 cm ^-1 And block VSe ₂ The Raman spectra are consistent, and the prepared quantum dot is proved to be VSe ₂ And (4) quantum dots.

The protection of the present invention is not limited to the above embodiments. Variations and advantages that may occur to those skilled in the art may be incorporated into the invention without departing from the spirit and scope of the inventive concept, and the scope of the appended claims is intended to be protected.

Claims

1. A method for preparing vanadium diselenide quantum dots by liquid phase stripping is characterized by comprising the following specific steps:

step 1: grinding the bulk crystal of vanadium diselenide into particles with the size of 0.1-0.01 mm by using a mortar;

step 2: filling the crushed vanadium diselenide into a glass container, and adding formamide into the glass container, wherein the preparation concentration is 20-100 mg/ml, and the liquid level height range of the formamide in the glass container is 2-10 cm;

and step 3: pre-ultrasonic treating the mixed solution of vanadium diselenide and formamide in an ultrasonic instrument with ice-water bath for 2-5 hr; the ice-water mixed bath means that a sample is kept warm in a mixture of ice and water, and the temperature of the ice-water mixture is 0 ℃, so that the temperature of the vanadium diselenide/formamide mixed solution is kept near 0 ℃ in the ultrasonic process;

and 4, step 4: further crushing the pre-sonicated vanadium diselenide/formamide mixed solution by using a probe type ultrasonic cell crusher; the distance of the probe extending into the liquid level of the solution is 1 cm; the breaking power of the probe type ultrasonic cell crusher is 60-100 watts, the working cycle of the ultrasonic probe is 1-5 seconds of working and 1-4 seconds of stopping, and the total breaking time is 2-5 hours; the whole ultrasonic process adopts ice-water mixed bath;

and 5: putting the vanadium diselenide/formamide mixed solution crushed by the probe type ultrasonic cell crusher into a centrifugal tube, and centrifuging in a centrifugal machine; 6000-8000 rpm, and 20-40 minutes of centrifugation time;

step 6: and collecting the centrifuged supernatant to obtain the metallic vanadium diselenide quantum dots dispersed in the formamide.