Simple and rapid preparation method of carbon quantum dots
The preparation of carbon quantum dots by high-temperature calcination of sodium carbonate and catalytic cracking of organic carbon sources solves the problems of complex preparation and strict equipment requirements in existing technologies, and realizes simple, rapid preparation and large-scale production of carbon quantum dots.
Patent Information
- Application Number
- CN202411719407.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-28
- Publication Date
- 2025-11-07
AI Technical Summary
Existing methods for preparing carbon quantum dots are complex, require strict equipment, and are difficult to control precisely in size. Furthermore, the "bottom-up" method suffers from the problems of complex preparation methods and strict equipment requirements.
Sodium carbonate was used as a template salt. After high-temperature calcination, it was immediately immersed in an organic carbon source for catalytic cracking reaction to form carbon quantum dots. Subsequently, solid-liquid separation, washing, centrifugation, dialysis and drying were performed to obtain carbon quantum dots.
A simple, rapid, and environmentally friendly method for preparing carbon quantum dots has been developed, which has the advantage of large-scale production, short reaction time, and strong operability.
Smart Images
Figure CN120903480A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of carbon material preparation, and particularly relates to a preparation method of carbon quantum dots. BACKGROUND
[0002] Carbon quantum dots are a kind of nanomaterials composed of carbon elements, and the size is usually less than 10 nanometers. Due to excellent optical, electrical and chemical properties, carbon quantum dots have attracted great research interest in the scientific community, and carbon quantum dots have rapidly become an important research object in the fields of material science, biomedicine, optoelectronic devices and the like due to unique fluorescence characteristics, good biocompatibility and low toxicity.
[0003] In the preparation of carbon quantum dots, there are mainly two strategies: "top-down" and "bottom-up" methods. The "top-down" method is mainly through crushing of bulk carbon materials, such as using acid oxidation, chemical etching or mechanical ball milling and the like. However, these methods usually bring environmental pollution or high energy consumption, and it is difficult to accurately control the size of carbon quantum dots. The "bottom-up" method is to form nanoscale carbon quantum dots through thermal decomposition, hydrothermal method or microwave-assisted synthesis of organic small molecules or polymers. Among them, the hydrothermal method and the microwave-assisted method are common carbon quantum dot preparation methods. Compared with the "top-down" method, the "bottom-up" method is more flexible and environmentally friendly, and can realize the optimization of the performance of carbon quantum dots by selecting different precursors and reaction conditions. However, the "bottom-up" method also faces some challenges, such as complex preparation method, strict requirements for equipment and the like. SUMMARY
[0004] The present application aims to provide a preparation method of carbon quantum dots, and the preparation method provided by the present application is simple, does not require complex equipment, has strong operability, and is suitable for large-scale preparation of carbon quantum dots.
[0005] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:
[0006] The present application provides a preparation method of carbon quantum dots, comprising the following steps: heating sodium carbonate to 600-800 DEG C and calcining, and then placing in an organic carbon source to perform a catalytic cracking reaction, the organic carbon source is cracked to form carbon quantum dots, and a product liquid containing carbon quantum dots is obtained; the organic carbon source is ethylene glycol and / or glycerol.
[0007] Preferably, the mass of sodium carbonate to the volume of organic carbon source is 5-20 g:100 mL.
[0008] Preferably, the temperature of the organic carbon source is 0-5 DEG C.
[0009] Preferably, the time of the catalytic cracking reaction is 5-8 minutes.
[0010] Preferably, the holding time of the calcination is 2-5 minutes.
[0011] Preferably, the heating rate is 1-10℃ / min.
[0012] Preferably, after obtaining the product liquid containing the carbon quantum dots, the product liquid containing the carbon quantum dots is subjected to solid-liquid separation, the obtained liquid is washed with water and ethanol respectively and then centrifuged, the supernatant is subjected to dialysis, the retained liquid is rotary evaporated and dried to obtain the carbon quantum dots.
[0013] Preferably, the centrifugation speed is 5000-8000 rpm and the centrifugation time is 5-10 minutes.
[0014] Preferably, the drying temperature is 60-80℃.
[0015] Preferably, the molecular weight cut-off of the dialysis bag used for dialysis is 1000-3500D.
[0016] The application provides a preparation method of carbon quantum dots, comprising the following steps: heating sodium carbonate to 600-800℃ for holding and then placing it in an organic carbon source to perform a catalytic cracking reaction, the organic carbon source is cracked to form carbon quantum dots, and a product liquid containing the carbon quantum dots is obtained; the organic carbon source is ethylene glycol and / or glycerol.
[0017] The application adopts a "bottom-up" method, only needs sodium carbonate as a template salt, and can obtain carbon quantum dots by immersing the high-temperature calcined product in an organic carbon source immediately, compared with other "bottom-up" methods such as hydrothermal method and microwave method, the method has simpler steps, the raw material source is extensive and the operability is strong, and has the advantages of scale preparation.
[0018] In addition, the reaction time is short by using the method of the application, and the carbon quantum dots can be quickly obtained, and the catalytic cracking reaction only needs 5-8 minutes. BRIEF DESCRIPTION OF DRAWINGS
[0019] Figure 1 It is a preparation flow chart of carbon quantum dots;
[0020] Figure 2 It is a transmission electron microscope image of the carbon quantum dots obtained in Example 1;
[0021] Figure 3 It is a transmission electron microscope image of the carbon quantum dots obtained in Example 2;
[0022] Figure 4 It is a transmission electron microscope image of the carbon quantum dots obtained in Example 3;
[0023] Figure 5Comparison photographs of carbon quantum dots (left) and ethylene glycol (right) dispersed in ethylene glycol prepared in Example 1 under 365nm ultraviolet light irradiation;
[0024] Figure 6 The image shows the ultraviolet-absorption spectrum of the carbon quantum dots obtained in Example 1. Detailed Implementation
[0025] This invention provides a method for preparing carbon quantum dots, comprising the following steps: calcining sodium carbonate at 600-800°C and then placing it in an organic carbon source for catalytic cracking reaction, wherein the organic carbon source cracks to form carbon quantum dots, thereby obtaining a product liquid containing carbon quantum dots; wherein the organic carbon source is ethylene glycol and / or glycerol.
[0026] Unless otherwise specified, all raw materials used in this invention are commercially available products well known in the art.
[0027] In this invention, the sodium carbonate is preferably anhydrous sodium carbonate; the sodium carbonate is preferably in powder form; the heating rate is preferably 1 to 10°C / minute, and in specific embodiments, it can be 1°C / minute, 3°C / minute, 5°C / minute, 8°C / minute or 10°C / minute.
[0028] In this invention, the calcination temperature can specifically be 600℃, 650℃, 700℃, 750℃, or 800℃; the calcination holding time is preferably 2 to 5 minutes, and in specific embodiments, it can be 2 minutes, 3 minutes, 4 minutes, or 5 minutes. In this invention, the calcination is preferably carried out in an air atmosphere.
[0029] In this invention, the temperature of the organic carbon source is preferably 0–5°C. In specific embodiments, the temperature of the organic carbon source can be 0°C, 1°C, 2°C, 3°C, 4°C, or 5°C. This invention uses a low-temperature organic carbon source, which can prevent the organic carbon source from evaporating due to excessively high temperatures during the reaction, thus reducing the loss of the organic carbon source. In this invention, when the organic carbon source is ethylene glycol and glycerol, there are no special requirements for their ratio; any ratio is acceptable. In the embodiments of this invention, the volume ratio of the two is 1:1.
[0030] In this invention, the preferred mass ratio of sodium carbonate to organic carbon source is 5-20 g:100 mL; in specific embodiments, the mass ratio of sodium carbonate to organic carbon source can be 5 g:100 mL, 8 g:100 mL, 10 g:100 mL, 15 g:100 mL, 17 g:100 mL or 20 g:100 mL, and so on.
[0031] In this invention, the catalytic cracking reaction time is preferably 5 to 8 minutes, and in specific embodiments, it can be 5 minutes, 6 minutes, 7 minutes or 8 minutes.
[0032] In the catalytic cracking process, sodium carbonate is used as a catalyst, and the organic carbon source is cracked to form carbon quantum dots under the action of sodium carbonate.
[0033] After obtaining the product liquid containing carbon quantum dots, the application preferably further comprises: performing solid-liquid separation on the product liquid containing carbon quantum dots, washing the obtained liquid with water and ethanol respectively, then centrifuging, dialyzing the obtained supernatant, and drying the retained liquid by rotary evaporation to obtain the carbon quantum dots.
[0034] The application does not have special requirements for the solid-liquid separation method, and a solid-liquid separation method known in the art can be used, such as filtration.
[0035] The application uses water to dissolve the residual sodium carbonate, and uses ethanol to dissolve the remaining organic carbon source and other organic matters produced by cracking.
[0036] The application preferably repeatedly performs washing, and the number of times of washing can be 2, 3 or 4.
[0037] In the application, the rotation speed of centrifugation is preferably 5000-8000 rpm, and the centrifugation time is preferably 5-10 minutes; in specific embodiments, the rotation speed of centrifugation can be 5000 rpm, 6000 rpm, 7000 rpm or 8000 rpm, and the centrifugation time can be 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes or 10 minutes.
[0038] In the application, the molecular weight cut-off of the dialysis bag used for dialysis is preferably 1000-3500 D; the dialysis is preferably performed in distilled water; and the dialysis time is preferably 30-50 h, more preferably 48 h. The application uses dialysis to precipitate residual sodium carbonate solution and other organic impurities, and retains the aqueous solution containing carbon quantum dots in the dialysis bag.
[0039] In the application, the temperature of rotary evaporation is preferably 80-100℃, and the application does not have special requirements for the rotary evaporation time, and the solution can be evaporated to dryness.
[0040] In the application, the drying temperature is preferably 60-80℃, and in specific embodiments, the drying temperature can be 60℃, 70℃ or 80℃. The application does not have special requirements for the drying time, and surface drying is appropriate. In the application, the drying is preferably performed in a blast drying oven.
[0041] Figure 1 A flow chart for the preparation of carbon quantum dots. In the application, sodium carbonate is calcined by heating to 600-800℃, and then placed in an organic carbon source to perform a catalytic cracking reaction, and the organic carbon source is cracked to form carbon quantum dots.
[0042] The present application adopts a "bottom-up" method, only needs sodium carbonate as a template salt, and can obtain carbon quantum dots by immersing in an organic carbon source immediately after high-temperature calcination. Compared with other "bottom-up" methods such as hydrothermal method and microwave method, the method has the advantages of simpler steps, wide raw material sources and strong operability, and has the advantage of scale preparation.
[0043] In addition, the method has the advantages of short reaction time, fast preparation of carbon quantum dots, and only 5-8 minutes of catalytic cracking reaction.
[0044] The preparation method of the carbon quantum dots provided by the present application will be described in detail below in combination with examples, but they should not be understood as limiting the scope of protection of the present application.
[0045] Example 1
[0046] 10 g of anhydrous sodium carbonate powder was placed in a quartz boat, and then heated to 750 DEG C at an air atmosphere in a muffle furnace at a heating rate of 5 DEG C / min, and the holding time was 5 min. Then, the quartz boat was quickly transferred into 100 mL of 10 DEG C ethylene glycol, and after 5 min of reaction, the solution was filtered, and the template salt sodium carbonate was removed by repeated washing with distilled water and ethanol. Finally, the solution containing the carbon quantum dots was centrifuged at 5000 rpm for 5 min, and the supernatant was dialyzed with distilled water. The molecular weight cut-off of the dialysis bag was 2000 D, and after 48 h of dialysis, the retained solution in the dialysis bag was evaporated at 90 DEG C by rotary evaporation, and then dried at 60 DEG C to obtain the carbon quantum dots.
[0047] As shown in Figure 2 is a transmission electron microscope image of the carbon quantum dots obtained in this example, Figure 5 is a contrast photo of the carbon quantum dots dispersed in ethylene glycol (left) and ethylene glycol (right) prepared in Example 1 under 365 nm ultraviolet light irradiation, which shows that the carbon quantum dots emit green fluorescence under ultraviolet light irradiation, Figure 6 is the ultraviolet-absorption spectrum of the carbon quantum dots obtained in Example 1, which shows that the carbon quantum dots have two absorption peaks at 218 nm and 260 nm.
[0048] Example 2
[0049] 5 g of anhydrous sodium carbonate powder was placed in a quartz boat, and then heated to 800 DEG C at an air atmosphere in a muffle furnace at a heating rate of 5 DEG C / min, and the holding time was 10 min. Then, the quartz boat was quickly transferred into 100 mL of 10 DEG C glycerol, and after 5 min of reaction, the solution was filtered, and the template salt sodium carbonate was removed by repeated washing with distilled water and ethanol. Finally, the solution containing the carbon quantum dots was centrifuged at 5000 rpm for 5 min, and the supernatant was dialyzed with distilled water. The molecular weight cut-off of the dialysis bag was 2000 D, and after 48 h of dialysis, the retained solution in the dialysis bag was evaporated at 90 DEG C by rotary evaporation, and then dried at 60 DEG C to obtain the carbon quantum dots, as shown in Figure 3 .
[0050] Example 3
[0051] 5 g of anhydrous sodium carbonate powder was placed in a quartz boat, and then placed in a muffle furnace air atmosphere heated to 800℃, the heating rate was 5℃ / min, the holding time was 8 min, and then it was taken out and quickly placed in a 10℃ 50 mL ethylene glycol, 50 mL glycerol mixed solution, after 5 min of reaction, filtration, repeated washing with distilled water, ethanol to remove template salt sodium carbonate, finally the solution containing carbon quantum dots was collected and centrifuged at 5000 rpm for 5 min, the supernatant was taken and dialyzed with distilled water, after dialysis for 48 h, the retained liquid in the dialysis bag was rotary evaporated at 90℃ until the solution evaporated, and then dried at 60℃ to obtain carbon quantum dots, as shown in Figure 4
[0052] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.
Claims
1. A method for preparing carbon quantum dots, characterized by, The method comprises the following steps: The sodium carbonate is heated to 600-800℃ and calcined, and then placed in an organic carbon source to perform a catalytic cracking reaction, the organic carbon source is cracked to form carbon quantum dots, and a product liquid containing the carbon quantum dots is obtained; the organic carbon source is ethylene glycol and / or glycerol.
2. The production method according to claim 1, characterized by, The mass of the sodium carbonate to the volume of the organic carbon source is 5-20g:100mL.
3. The preparation method according to claim 1, characterized in that, The temperature of the organic carbon source is 0-5℃.
4. The process according to any one of claims 1 to 3, characterized in that, The time of the catalytic cracking reaction is 5-8 minutes.
5. The preparation method according to claim 1, characterized in that, The holding time of the calcination is 2-5 minutes.
6. The production method according to claim 1 or 5, characterized by, The heating rate is 1-10℃ / minute.
7. The preparation method according to claim 1, characterized in that, After the product liquid containing the carbon quantum dots is obtained, the product liquid is further subjected to solid-liquid separation, the obtained liquid is washed with water and ethanol respectively and then centrifuged, the supernatant is dialyzed, the retained liquid is rotary evaporated and dried to obtain the carbon quantum dots.
8. The preparation method according to claim 7, characterized in that, The centrifugation speed is 5000-8000rpm, and the centrifugation time is 5-10 minutes.
9. The preparation method according to claim 7, characterized in that, The drying temperature is 60-80℃.
10. The preparation method according to claim 7, characterized in that, The molecular weight cut-off of the dialysis bag used for dialysis is 1000-3500D.