CN117143598A - A high-entropy carbon quantum dot nanomaterial and its preparation method and application - Google Patents

Abstract

The application provides a high-entropy carbon quantum dot nanomaterial, a preparation method and application thereof, wherein the nanomaterial consists of a carbon core and a polymer chain segment, the polymer chain segment surrounds the carbon core, and the carbon core is regularly gathered through the polymer chain segment to form a spherical high-entropy carbon quantum dot with secondary aggregation; the high-entropy carbon quantum dot nano material at least contains 5 nonmetallic elements; the particle size of the carbon quantum dots is between 1 and 4nm, and the lattice spacing of the carbon cores is between 0.15 and 0.3nm; the nano material provided by the application has various nonmetallic elements and rich functional group structures, and has excellent fluorescence performance when being applied as a fluorescent material.

Description

A high-entropy carbon quantum dot nanomaterial and its preparation method and application

Technical field

The present invention relates to the technical field of fluorescent nanomaterials, and more specifically, to a high-entropy carbon quantum dot nanomaterial and its preparation method and application.

Background technique

In the past few decades, carbon-based nanomaterials such as carbon nanotubes, fullerenes, and graphene have been widely studied due to their superior properties and have shown good application prospects in many fields. Carbon quantum dots, as an emerging carbon nanomaterial, generally refer to zero-dimensional carbon nanoparticles with dimensions of less than 10 nm in three dimensions and usually have fluorescent properties. Compared with traditional semiconductor quantum dots and organic dyes, carbon quantum dots have the advantages of low toxicity, abundant sources, easy functionalization, good biocompatibility, good photostability, and adjustable fluorescence wavelength. They are widely used in biomedicine, environmental protection, It has potential application value in the fields of photoelectrocatalysis, energy storage and conversion.

In recent years, carbon quantum dots are in a stage of rapid development, and the number of related papers has shown a rapid growth trend. Various new methods for preparing carbon quantum dots have also been developed, and the formation mechanism and complex structure of carbon quantum dots have been semi-quantitatively analyzed through theoretical calculations and advanced characterization techniques.

Generally speaking, the synthesis methods of carbon quantum dots can be roughly divided into two categories: "top-down" method and "bottom-up" method. Among them, the "top-down" method is to cut large-sized carbon targets (such as graphene, graphitic carbon nitride, fullerene, coke, etc.) into small-sized carbon quantum dots through physical or chemical methods. The bottom-up method uses small organic molecules (such as citric acid, glucose, acetaldehyde, phenylenediamine, etc.) as precursors to obtain carbon quantum dots through a series of polymerization, carbonization and other reactions. As far as the "top-down" method is concerned, oxidative cutting, arc discharge and laser ablation are the more commonly used carbon quantum dot preparation methods in early research. This reaction uses external energy to decompose a large-sized carbon target precursor to form gas plasma and then recombine it to obtain carbon quantum dots. The difference is that the former is driven by ultra-high external voltage, while the latter is driven by high-energy laser pulses. Generally speaking, the fluorescence properties of carbon quantum dots prepared by this method are poor and involve complex purification and separation processes. In addition, the above methods also have many disadvantages such as high cost and demanding equipment requirements. The "bottom-up" method mainly includes pyrolysis method, template method, etc. Pyrolysis refers to the process in which carbon-containing precursors are carbonized or polymerized to form carbon quantum dots under external heating or self-exothermic conditions. In principle, all carbon-containing precursors (such as citric acid, phenylenediamine, biomass, etc.) can be used to generate carbon quantum dots through the pyrolysis process. The template method refers to a method of generating carbon quantum dots with specific shapes with the assistance of template molecules. Although carbon quantum dots can be synthesized by a variety of methods, the yields of carbon quantum dots synthesized by most of the above methods are generally low, and the synthesized carbon quantum dots usually only have 1 or 2 types of heteroatoms doped, making their functions relatively limited. limited. How to achieve large-scale production and multi-functionality of carbon quantum dots is still an urgent problem to be solved.

Contents of the invention

Based on the above technical problems existing in the prior art, the present invention provides a high-entropy carbon quantum dot nanomaterial, which contains a variety of non-metallic elements and functional group structures. As a fluorescent material, it exhibits excellent fluorescence properties.

Specifically, the technical solutions of the present invention are as follows:

A high-entropy quantum dot nanomaterial, consisting of a carbon core and a polymer chain segment. The polymer chain segment surrounds the carbon core. The carbon core regularly aggregates through the polymer chain segment to form secondary agglomeration. Spherical high-entropy carbon quantum dots; the high-entropy carbon quantum dot nanomaterials contain at least 5 non-metallic elements; the particle size of the carbon quantum dots is between 1-4nm, and the lattice spacing of the carbon core is 0.15 -0.3nm.

In some embodiments, the non-metal elements include carbon, oxygen, fluorine, nitrogen, and sulfur.

The present invention also provides a method for preparing the high-entropy carbon quantum dot nanomaterial according to any of the above embodiments, which method includes the following steps:

The organic compound precursors are mixed evenly and reacted under alkaline conditions to obtain the high-entropy carbon quantum dots; wherein the organic compound precursors include α-H-containing aldehydes or ketones, fluorine-containing aromatic aldehydes, and fluorine-containing aromatic aldehydes. Sulfur amino acids.

In some embodiments, the method includes the following steps:

Mix the organic compound precursor evenly to obtain a mixed solution; completely disperse the solid alkali in water to form an alkaline solution, then add the alkaline solution to the mixed solution while it is hot, and stir to react; after the reaction is completed , solid-liquid separation, adding water to the solid product and ultrasonic dispersion, and then transferring it to a dialysis bag for dialysis to neutrality to obtain the high-entropy carbon quantum dot nanomaterial.

In some embodiments, the solid base includes at least one of potassium hydroxide, sodium hydroxide, and lithium hydroxide.

In some embodiments, the reaction time is 2-3h.

In some embodiments, the concentration of the alkaline solution is 0.5-12 mol/L; preferably, it is 1-10 mol/L.

In some embodiments, the α-H-containing aldehyde includes at least one of monovalent aliphatic aldehydes, dibasic aliphatic aldehydes, polyvalent aliphatic aldehydes, monovalent aromatic aldehydes, dibasic aromatic aldehydes, and polyvalent aromatic aldehydes.

In some embodiments, the sulfur-containing amino acid includes at least one of methionine, cystine, and cysteine.

In some embodiments, the fluorine-containing aromatic aldehyde includes p-fluorobenzaldehyde, 2-fluorobenzaldehyde, 3-fluorobenzaldehyde, pentafluorobenzaldehyde, p-fluorobenzaldehyde, 2,6-difluorobenzaldehyde , 3,5-difluorobenzaldehyde, o-trifluoromethylbenzaldehyde, 3-(trifluoromethyl)benzaldehyde, 4-(trifluoromethyl)benzaldehyde, 2,3,4,5-tetrafluoro Benzaldehyde, 2-fluoro-3-methoxybenzaldehyde, 2,3,5-trifluorobenzaldehyde, 3,4-difluorobenzaldehyde, 3,5-bis(trifluoromethyl)benzaldehyde, 2 , at least one of 5-difluorobenzaldehyde, 2,3-difluorobenzaldehyde, 2,4-difluorobenzaldehyde, and 2,4,5-trifluorobenzaldehyde.

The present invention also provides the application of the high-entropy carbon quantum dot nanomaterial obtained by the preparation method of any of the above embodiments as a fluorescent material.

Compared with the existing technology, the beneficial effects of the present invention are as follows:

The invention is based on the aldol condensation reaction and the dehydration condensation reaction of amino acids. In an open system at room temperature and normal pressure, the aldehyde or ketone precursor containing α hydrogen atoms is first converted into an unsaturated aldehyde or ketone under alkaline conditions, and then During the synthesis process, unsaturated aldehydes or ketones undergo various substitution and condensation reactions with amino acids to form polymer chains with different functional groups or branches and small clusters, which are further curled, cross-linked and dehydrated to form the carbon core of carbon quantum dots; The uncarbonized polymer chains on the periphery surround the carbon core, and there are many heteroatom functional groups on them, giving the carbon quantum dots many properties. As the reaction ends, the mixture of carbon quantum dots settles to the bottom of the reactor. After ultrasonic treatment in a water environment, the carbon quantum dots were dispersed into the water. During the dialysis process, the small molecule precursors in the mixture enter the dialysate, while the carbon quantum dots remain in the dialysis bag. Finally, after the solvent water is removed by freeze-drying, high-entropy carbon quantum dot nanomaterials in powder form are obtained.

The carbon quantum dot nanomaterial obtained by the method of the present invention contains a variety of non-metallic elements and rich functional group structures. As a fluorescent material, it exhibits excellent fluorescence performance and can be used in fields such as optical sensing and imaging.

Description of the drawings

Figure 1 is a schematic structural diagram of the high-entropy carbon quantum dots of the present invention;

Figure 2 is an HRTEM image of the high-entropy carbon quantum dots of the present invention, in which (A) is attached with a size distribution curve of high-entropy carbon quantum dots; (B) is attached with a schematic diagram of the lattice spacing of high-entropy carbon quantum dots;

Figure 3 is an infrared spectrum of the high-entropy carbon quantum dots of the present invention;

Figure 4 is a nuclear magnetic resonance spectrum of the high-entropy carbon quantum dots of the present invention, in which (A) is ^{a 1} H spectrum and (B) is a ¹³ C spectrum;

Figure 5 is an XPS pattern of the high-entropy carbon quantum dots of the present invention;

Figure 6 is a high-resolution mass spectrum of the high-entropy carbon quantum dots of the present invention; A and B are the peak intensities in different mass-to-charge ratio ranges respectively.

Figure 7 is a fluorescence emission spectrum diagram of the high-entropy carbon quantum dots of the present invention under excitation light with a wavelength of 500 nm.

Detailed ways

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, the present invention can be implemented in many other ways different from those described here. Those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited to the specific implementation disclosed below.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which the invention belongs. The terminology used herein in the description of the invention is for the purpose of describing specific embodiments only and is not intended to limit the invention.

Unless otherwise specified, the reagents, raw materials, etc. in the specific embodiments of the present invention are all commercially available.

Example 1

A method for preparing high-entropy carbon quantum dot nanomaterials, including the following steps:

S1. Dissolve 5g of cysteine in 15mL of deionized water, then add 10mL of acetaldehyde aqueous solution and continue stirring until uniform. Finally, add 10mL of p-fluorobenzaldehyde and continue rapid stirring;

S2. Add 5 mL of deionized water to 6 g of NaOH to dissolve it, add it to the mixed solution in step S1 above while it is hot, and continue to stir for 2-3 h, and finally let it stand for 3 days; then pour out the supernatant and add it to the precipitate. Deionized water was injected into the solution and ultrasonic dispersed. The dispersion was transferred to a 1000Da dialysis bag and dialyzed to neutrality. Finally, it was freeze-dried to obtain a light yellow powder.

The obtained product was subjected to relevant performance tests, and the test results are shown in Figure 2-6.

As shown in Figure 2, the particle size of the carbon quantum dot nanomaterial obtained in this embodiment is between 1-4 nm, and the average particle size is 2.32±0.52nm; and the lattice spacing of the carbon cores in the carbon quantum dot nanomaterial is approximately 0.25nm.

As can be seen from Figures 3 and 4, the nanomaterials obtained in this application have composition units as shown in Figure 1. Each unit is composed of a carbon core and a polymer chain segment. The polymer chain segment surrounds the carbon core and is on the chain segment. It has various functional group structures such as -OH, -NH-, C=O, C=C, C-N, etc.

After XPS analysis of the product, the obtained nanomaterial contains C, N, O, F, and S elements. The specific content of each element is shown in Figure 5 and Table 1 below.

Table 1 Contents of various elements in high-entropy carbon quantum dot materials

The obtained carbon quantum dot nanomaterial was tested for fluorescence performance, and the test results are shown in Figure 7.

Example 2

A method for preparing high-entropy carbon quantum dot nanomaterials, including the following steps:

S1. Dissolve 5g of cysteine in 15mL of deionized water, then add 10mL of acetaldehyde aqueous solution and continue stirring until uniform. Finally, add 10mL of p-fluorobenzaldehyde and continue rapid stirring;

S2. Add 5 mL of deionized water to 6 g of NaOH to dissolve it, add it to the mixed solution in step S1 above while it is hot, and continue stirring for 2-3 hours; then immediately pour out the supernatant and inject deionized water into the precipitate. After ultrasonic dispersion, the dispersion was transferred to a 1000Da dialysis bag and dialyzed to neutrality, and finally freeze-dried to obtain a light yellow powder.

After XPS analysis of the product, the obtained nanomaterial contains C, N, O, F, and S elements. The specific content of each element is shown in Table 2 below.

Table 2 Contents of various elements in high-entropy carbon quantum dot materials

After testing, the particle size of the carbon quantum dot nanomaterial obtained in this example is between 2-4 nm, and the average particle size is 2.52±0.42nm; and the lattice spacing of the carbon cores in the carbon quantum dot nanomaterial is about 0.23 nm.

The technical features of the above embodiments can be combined in any way. To simplify the description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, All should be considered to be within the scope of this manual.

The above-mentioned embodiments only express several implementation modes of the present invention. The descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the scope of protection of the patent of the present invention should be determined by the appended claims.

Claims (10)

1. A high-entropy carbon quantum dot nanomaterial, characterized in that it is composed of a carbon core and a polymer chain segment, the polymer chain segment surrounds the carbon core, and the carbon core passes through the polymer chain Segments are regularly aggregated to form secondary agglomerated spherical high-entropy carbon quantum dots; the high-entropy carbon quantum dot nanomaterial contains at least 5 non-metallic elements; the particle size of the carbon quantum dots is between 1-4nm, and the carbon The lattice spacing of the core is 0.15-0.3nm. 2. The high-entropy carbon quantum dot nanomaterial according to claim 1, wherein the non-metal elements include carbon, oxygen, fluorine, nitrogen, and sulfur. 3. The preparation method of high-entropy carbon quantum dot nanomaterials according to claim 1 or 2, characterized in that it includes the following steps: The organic compound precursors are mixed evenly and reacted under alkaline conditions to obtain the high-entropy carbon quantum dots; wherein the organic compound precursors include α-H-containing aldehydes or ketones, fluorine-containing aromatic aldehydes, and fluorine-containing aromatic aldehydes. Sulfur amino acids. 4. The preparation method of high-entropy carbon quantum dot nanomaterials according to claim 3, characterized in that it includes the following steps: Mix the organic compound precursor evenly to obtain a mixed solution; completely disperse the solid alkali in water to form an alkaline solution, then add the alkaline solution to the mixed solution while it is hot, and stir to react; after the reaction is completed , solid-liquid separation, adding water to the solid product and ultrasonic dispersion, and then transferring it to a dialysis bag for dialysis to neutrality to obtain the high-entropy carbon quantum dot nanomaterial. 5. The method for preparing high-entropy carbon quantum dot nanomaterials according to claim 4, wherein the solid base includes at least one of potassium hydroxide, sodium hydroxide, and lithium hydroxide. 6. The method for preparing high-entropy carbon quantum dot nanomaterials according to claim 3, characterized in that the reaction time is 2-3h. 7. The preparation method of high-entropy carbon quantum dot nanomaterials according to claim 3, characterized in that the α-H-containing aldehydes include monovalent aliphatic aldehydes, dibasic aliphatic aldehydes, polybasic aliphatic aldehydes, monovalent aromatic aldehydes, At least one of dibasic aromatic aldehydes and polybasic aromatic aldehydes. 8. The method for preparing high-entropy carbon quantum dot nanomaterials according to claim 3, wherein the sulfur-containing amino acids include at least one of methionine, cystine and cysteine. 9. The preparation method of high-entropy carbon quantum dot nanomaterials according to claim 3, characterized in that the fluorine-containing aromatic aldehydes include p-fluorobenzaldehyde, 2-fluorobenzaldehyde, 3-fluorobenzaldehyde, pentafluorobenzaldehyde, Fluorobenzaldehyde, p-fluorobenzaldehyde, 2,6-difluorobenzaldehyde, 3,5-difluorobenzaldehyde, o-trifluoromethylbenzaldehyde, 3-(trifluoromethyl)benzaldehyde, 4-( Trifluoromethyl)benzaldehyde, 2,3,4,5-tetrafluorobenzaldehyde, 2-fluoro-3-methoxybenzaldehyde, 2,3,5-trifluorobenzaldehyde, 3,4-difluoro Benzaldehyde, 3,5-bis(trifluoromethyl)benzaldehyde, 2,5-difluorobenzaldehyde, 2,3-difluorobenzaldehyde, 2,4-difluorobenzaldehyde, 2,4,5- At least one kind of trifluorobenzaldehyde. 10. Application of the high-entropy carbon quantum dot nanomaterial as claimed in claim 1 or 2 or the high-entropy carbon quantum dot nanomaterial obtained by the preparation method as claimed in any one of claims 3 to 9 as a fluorescent material.