CN111675207A

CN111675207A - Simple preparation method of fluorescent carbon dots

Info

Publication number: CN111675207A
Application number: CN202010570927.4A
Authority: CN
Inventors: 刘文晶; 王得印; 高辉; 王育华; 杜鑫宇; 苏晓燕
Original assignee: Lanzhou University
Current assignee: Lanzhou University
Priority date: 2020-06-22
Filing date: 2020-06-22
Publication date: 2020-09-18

Abstract

A simple preparation method of a fluorescent carbon dot is based on a solution combustion method, glycine is used as a reducing agent, nitrate is used as an oxidizing agent, the glycine is dissolved in water according to a certain proportion, and the glycine and the nitrate are heated on an electric heating plate with the surface temperature of 150-. And (4) selecting a proper solvent for dissolving, and performing suction filtration to obtain a light yellow carbon dot solution. The method has the advantages of wide raw material source, low price, simple preparation process, very easy achievement of condition requirements and environment-friendly preparation process. The emission spectrum of the carbon dots prepared by the method shows the dependence on the excitation wavelength.

Description

Simple preparation method of fluorescent carbon dots

Technical Field

The invention relates to a fluorescent carbon dot preparation technology, in particular to a technology for preparing fluorescent carbon dots by taking glycine and nitrate as raw materials.

Background

In recent years, carbon dots have attracted a lot of attention due to their great potential for applications in the fields of bio-imaging, drug delivery, optical probes, light emitting diodes, and the like. The fluorescent carbon dots have the characteristics of simple functionalization, high quantum efficiency, good chemical stability, no toxicity, strong detection capability and the like, show great application advantages in the detection of harmful ions or compounds, and are widely researched. At present, the main methods for preparing fluorescent carbon dots include hydrothermal (solvent) thermal methods, thermal decomposition methods, vapor phase chemical deposition methods, microwave-assisted synthesis methods, ultrasonic-assisted synthesis methods, and the like, which are based on small molecules, and laser ablation methods, electrochemical methods, arc discharge methods, and the like, which are based on graphite substrates. Some of these methods require a long time, some require a high temperature, and some require expensive equipment, so that the preparation cost of the fluorescent carbon dot is high and the method is not easy to popularize.

Disclosure of Invention

The invention aims to provide a simple preparation method of a fluorescent carbon dot.

The invention relates to a simple preparation method of fluorescent carbon dots, which comprises the following steps:

step (1) comprises the following steps of: x and x <5, weighing glycine and nitrate, putting the glycine and the nitrate into a beaker, adding water to dissolve the glycine and the nitrate, and preparing a clear aqueous solution;

placing the obtained aqueous solution on an electric heating plate, setting the surface temperature of the electric heating plate to be 150 ℃ and 250 ℃, and heating until the water is completely evaporated, wherein the reaction can be carried out within minutes;

selecting a proper solvent to dissolve and suction-filtering a product obtained by the reaction to obtain a light yellow carbon dot solution; purifying according to actual conditions to obtain a pure carbon dot solution; the target carbon spot was obtained after freeze-drying.

The invention has the advantages that: the invention takes glycine and nitrate as raw materials, a beaker as a reaction vessel, and an electric heating plate is heated to 150 ℃ and 250 ℃ for rapid reaction, thereby completing the synthesis process in a very short time. The method has the advantages of wide raw material source, low price, simple preparation process, very easy achievement of condition requirements, environmental friendliness and very easy popularization.

Drawings

Fig. 1 is an emission spectrum of a carbon dot prepared in example 1 at different excitation wavelengths, fig. 2 is an excitation spectrum of a carbon dot prepared in example 1 monitored at 420nm and an emission spectrum of a carbon dot prepared in example 1 excited at 360nm, fig. 3 is an emission spectrum of a carbon dot prepared in example 2 at different excitation wavelengths, fig. 4 is an emission spectrum of a carbon dot prepared in example 3 at different excitation wavelengths, fig. 5 is an emission spectrum of a carbon dot prepared in example 4 at different excitation wavelengths, and fig. 6 is an emission spectrum of a carbon dot prepared in example 5 at different excitation wavelengths.

Detailed Description

The simple preparation method of the fluorescent carbon dots is based on a solution combustion method, and glycine is used as a reducing agent and nitrate is used as an oxidizing agent.

In the simple preparation method of the fluorescent carbon dots, the nitrate comprises ammonium nitrate and metal nitrate, including alkali metal nitrate, alkaline earth metal nitrate, transition metal nitrate and rare earth nitrate.

In the above simple preparation method of the fluorescent carbon dot, the nitrate as the oxidant may be one nitrate compound or a mixture of multiple nitrate compounds.

In the simple preparation method of the fluorescent carbon dots, the mass ratio of glycine to nitrate is 1: x, x <5, preferably stoichiometric.

In the above simple preparation method of the fluorescent carbon dots, the surface temperature of the electric heating plate is 150-.

The method is based on a solution combustion method, glycine is used as a reducing agent, nitrate is used as an oxidizing agent, the glycine and the nitrate are dissolved in water according to a certain proportion to prepare an aqueous solution, and the aqueous solution is heated on an electric hot plate to initiate a violent combustion reaction. After the reaction is finished, selecting a proper solvent according to a product obtained by the reaction for dissolving, and performing suction filtration to obtain a light yellow carbon dot solution. According to the specific requirements of application, the fluorescent carbon dots can be correspondingly purified, and pure carbon dots can be obtained. The method has the advantages of wide raw material source, low price, simple preparation process, very easy achievement of condition requirements, environment-friendly preparation process and very easy popularization.

The present invention will be further described with reference to the following drawings and specific examples, which show detailed embodiments and specific procedures, but the scope of the present invention is not limited to the following examples.

Example 1:

weighing 1.08 g of glycine and 3.24 g of aluminum nitrate nonahydrate respectively, putting the glycine and the aluminum nitrate nonahydrate into a beaker, adding water to dissolve the glycine and the aluminum nitrate nonahydrate, and preparing a clear aqueous solution;

and (2) placing the aqueous solution obtained in the step (1) on an electric heating plate, setting the surface temperature of the electric heating plate to be 195 ℃, and heating until reaction occurs. Adding distilled water into the reaction product to obtain a suspension;

and (3) performing suction filtration on the suspension obtained in the step (2) by using a microporous filter membrane to obtain a light yellow filtrate, namely the carbon dot product solution.

Characterization of the properties of the product carbon dots is shown in fig. 1, fig. 2 and fig. 3, where fig. 1 shows the emission spectra of the carbon dots prepared in example 1 at different excitation wavelengths, and fig. 2 shows the excitation spectra of the carbon dots prepared in example 1 at 420nm and the emission spectra at 360 nm. It can be seen that the fluorescent carbon dot has excitation wavelength dependence.

Example 2:

the same procedure as in example 1 was repeated except that the reactant nitrate was 5.18 g of ammonium nitrate.

Characterization of the properties of the product carbon dots is shown in fig. 3, where fig. 3 is the emission spectra of the carbon dots prepared in example 2 at different excitation wavelengths. It can be seen that the fluorescent carbon dot has excitation wavelength dependence.

Example 3:

the procedure of example 1 was repeated except that the reactant nitrate salt was 3.31 g of yttrium nitrate hexahydrate.

Characterization of the properties of the product carbon dots is shown in fig. 4, where fig. 4 is the emission spectra of the carbon dots prepared in example 3 at different excitation wavelengths. It can be seen that the fluorescent carbon dot has excitation wavelength dependence.

Example 4:

the same as example 3 except that the mass of glycine was 0.65 g.

Characterization of the properties of the product carbon dots is shown in fig. 5, where fig. 5 is the emission spectra of the carbon dots prepared in example 4 at different excitation wavelengths. It can be seen that the fluorescent carbon dot has excitation wavelength dependence.

Example 5:

the procedure is as in example 1 except that the reactants are 1.0 g of glycine, 2.2480 g of aluminum nitrate nonahydrate, 0.7685 g of magnesium nitrate hexahydrate.

Characterization of the properties of the product carbon dots is shown in fig. 6, where fig. 6 is the emission spectra of the carbon dots prepared in example 5 at different excitation wavelengths. It can be seen that the fluorescent carbon dot has excitation wavelength dependence.

Claims

1. A simple preparation method of a fluorescent carbon dot is characterized by comprising the following steps:

placing the obtained aqueous solution on an electric heating plate, setting the surface temperature of the electric heating plate to be 150-250 ℃, and heating until water is completely evaporated, wherein the reaction can be carried out within minutes;

2. The method of claim 1, wherein the method is based on a solution combustion method, and glycine is used as a reducing agent and nitrate is used as an oxidizing agent.

3. The method of claim 1, wherein the nitrate comprises ammonium nitrate and metal nitrate, including alkali metal nitrate, alkaline earth metal nitrate, transition metal nitrate, rare earth nitrate.

4. The method for preparing a fluorescent carbon dot in a simple manner as claimed in claim 1, wherein the nitrate as the oxidant may be a nitrate compound or a mixture of nitrate compounds.

5. The simplified method for producing a fluorescent carbon dot as set forth in claim 1, wherein the ratio of the amounts of glycine and nitrate is 1: x, x <5, preferably stoichiometric.

6. The simple preparation method of fluorescent carbon dots according to claim 1, wherein the surface temperature of the electric heating plate is 150-250 ℃, preferably 190-210 ℃.