CN113913185B - Carbon quantum dot and preparation method thereof - Google Patents
Carbon quantum dot and preparation method thereof Download PDFInfo
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 105
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- 125000004432 carbon atom Chemical group C* 0.000 claims description 26
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims description 23
- 239000011324 bead Substances 0.000 claims description 23
- 229910052726 zirconium Inorganic materials 0.000 claims description 23
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- 238000000034 method Methods 0.000 claims description 19
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 18
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- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 6
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- 239000002086 nanomaterial Substances 0.000 abstract description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 26
- 229910052799 carbon Inorganic materials 0.000 description 20
- 239000008367 deionised water Substances 0.000 description 20
- 229910021641 deionized water Inorganic materials 0.000 description 20
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- 238000009396 hybridization Methods 0.000 description 15
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 14
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- 229910003481 amorphous carbon Inorganic materials 0.000 description 4
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- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
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- 229910052760 oxygen Inorganic materials 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
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- 230000009467 reduction Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
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- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/65—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing carbon
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y40/00—Manufacture or treatment of nanostructures
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Abstract
The invention belongs to the technical field of nano materials, and particularly relates to a carbon quantum dot and a preparation method thereof. The preparation method of the carbon quantum dot comprises the following steps: providing a carbon material; etching the carbon material by using alkali metal hydroxide to obtain an etched carbon material; and stripping the etched carbon material, and then performing steam treatment to obtain the carbon quantum dots. The preparation method can improve the carrier mobility of the carbon quantum dot material, so that the obtained carbon quantum dot has good photoelectric performance.
Description
Technical Field
The invention belongs to the technical field of nano materials, and particularly relates to a carbon quantum dot and a preparation method thereof.
Background
Quantum dot materials are considered to have wide application in the fields of photoelectric display, medical monitoring, biosensors and the like due to their unique optical properties, and are becoming a research hotspot. However, the traditional quantum dot material contains heavy metal elements such as Cd, te and the like, so that the cost is high, and the material has stronger biotoxicity; on the other hand, the traditional quantum dot material needs to strictly control the moisture and oxygen content of the system in the preparation process, which puts forward strict requirements on the synthesis equipment and process of the quantum dot material, thereby limiting the application and development of the quantum dot material.
In recent years, various novel quantum dot materials with environmental friendliness and low cost are developed successively, and the carbon-based quantum dot is considered as a potential novel photoelectric material due to the characteristics of stable fluorescence performance, low reaction activity, good water solubility and the like. At present, biomass material carbonization, dispersion, purification and other operations are generally adopted to prepare the carbon quantum dot material, and as the carbon material obtained by biomass carbonization belongs to amorphous carbon, sp exists simultaneously 2 Hybridization and sp 3 Hybridized carbon atoms, therefore, partial sp also exists in the carbon quantum dots prepared by taking biomass as raw material 3 The hybridized carbon atoms are unfavorable for the movement of carriers in the carbon quantum dot material, so that the carrier mobility is low, and the photoelectric performance of the carbon quantum dot material is affected. Thus limiting the application of the carbon quantum dot material in the field of photoelectric devices.
Accordingly, the prior art is in need of improvement.
Disclosure of Invention
The invention aims to provide a carbon quantum dot and a preparation method thereof, and aims to solve the technical problem of how to improve carrier mobility of the carbon quantum dot.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the invention provides a preparation method of carbon quantum dots, which comprises the following steps:
providing a carbon material;
etching the carbon material by using alkali metal hydroxide to obtain an etched carbon material;
and stripping the etched carbon material, and then performing steam treatment to obtain the carbon quantum dots.
The preparation method of the carbon quantum dot provided by the invention comprises the steps of firstly etching a carbon material by using alkali metal hydroxide to enable the carbon material to generate pores so as to destroy the microstructure of the carbon material, then collapsing and tearing the etched carbon material microstructure by stripping to generate an initial carbon quantum dot, and after the initial carbon quantum dot is treated by water vapor, utilizing sp 2 Hybridization, sp 3 The difference of reactivity of hybridized carbon atoms can eliminate sp in the material by water vapor 3 The carrier mobility of the finally obtained carbon quantum dot material is improved by hybridization of carbon atoms, so that the carbon quantum dot obtained by the preparation method has good photoelectric performance. In addition, the carbon quantum dot material obtained by the preparation method does not contain heavy metals such as Cd, te and the like, and has wider application field compared with the traditional quantum dot material, and the preparation method is simple in operation, low in cost, environment-friendly and suitable for industrial application.
The invention also provides a carbon quantum dot which is prepared by the preparation method of the carbon quantum dot.
The carbon quantum dot provided by the invention is prepared by the preparation method of the special carbon quantum dot, so that the carbon quantum dot has more sp 2 The carbon atoms are hybridized, so that the carrier mobility of the carbon atoms can be improved, and the photoelectric performance is good.
Drawings
Fig. 1 is a schematic flow chart of a preparation method of a carbon quantum dot according to an embodiment of the invention.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the invention is further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
In one aspect, an embodiment of the present invention provides a method for preparing a carbon quantum dot, as shown in fig. 1, where the method includes the following steps:
s01: providing a carbon material;
s02: etching the carbon material by using alkali metal hydroxide to obtain an etched carbon material;
s03: and stripping the etched carbon material, and then performing steam treatment to obtain the carbon quantum dots.
According to the preparation method of the carbon quantum dot provided by the embodiment of the invention, firstly, the alkali metal hydroxide is used for etching the carbon material to enable the carbon material to generate pores so as to destroy the microstructure of the carbon material, then the etched carbon material microstructure is collapsed and torn by stripping to generate the initial carbon quantum dot, and after the initial carbon quantum dot is treated by water vapor, sp is utilized 2 Hybridization, sp 3 The difference of reactivity of hybridized carbon atoms can eliminate sp in the material by water vapor 3 The carrier mobility of the finally obtained carbon quantum dot material is improved by hybridization of carbon atoms, so that the carbon quantum dot obtained by the preparation method has good photoelectric performance. In addition, the carbon quantum dot material obtained by the preparation method does not contain heavy metals such as Cd, te and the like, and has wider application field compared with the traditional quantum dot material containing heavy metals, and the preparation method is simple in operation, low in cost, environment-friendly and suitable for industrial application.
The carbon atom has 1 s-orbit, 3 p-orbitals and 4 bonding orbitals. sp (sp) 2 Hybridization is one s orbit in carbon atoms, and 2 p orbitals are mutually fused to obtain 3 new bonding orbitals; sp (sp) 3 Hybridization is one s-orbit in a carbon atom, and 3 p-orbitals are fused with each other, resulting in 4 new bond-forming orbitals. sp (sp) 2 A hybridized carbon atom, an unhybridized p-orbital having a single electron capable of being bonded to an adjacent sp 2 HybridThe single electron on the carbon atom forms a delocalized pi bond (electrons on the delocalized pi bond can move freely, like free electrons of metallic materials), and therefore sp 2 The hybrid carbon atoms have good carrier mobility; at the same time sp 2 Bonding between hybridized carbon atoms, except for two sp 2 The hybridized orbitals form a sigma bond and also form a delocalized pi-to-pi (which can be understood as a carbon-carbon double bond), while sp 3 Only one sigma bond can be formed between the hybridized carbon atoms, so that the bond energy is smaller and the chemical activity is higher; thus, in the preparation process of the embodiment of the invention, the water vapor preferentially and sp 3 Hybridization of carbon atoms to remove sp from carbon materials 3 Hybridization of carbon atoms to protect sp 2 A hybridized carbon atom; and finally, the carrier mobility of the carbon quantum dot material is improved.
In the step S01, the carbon material may be a conventional carbon material, specifically, amorphous carbon, specifically amorphous carbon obtained by carbonizing biomass, a variety with a higher degree of carbonization, or sp with a higher degree of carbonization 2 More carbon atoms are hybridized, so that the yield of the carbon quantum dots is higher. The amorphous carbon obtained by carbonizing biomass has sp at the same time 2 Hybridization and sp 3 The hybridized carbon atoms, therefore, the preparation method can effectively remove sp 3 And hybridized carbon atoms, so that the carrier mobility of the carbon quantum dot material is finally improved.
In one embodiment, the carbon material is selected from at least one of carbon black, charcoal, coke, and activated carbon.
In the above step S02, the alkali metal hydroxide is selected from at least one of lithium hydroxide, sodium hydroxide and potassium hydroxide; the carbon material is etched by alkali metal hydroxide to generate pores, and the specific reaction can be expressed as: c+4moh=m 2 CO 3 +2M+2H 2 M is an alkali metal such as lithium, sodium, potassium, etc.
In one embodiment, the step of etching the carbon material with the alkali metal hydroxide to better impregnate the alkali metal hydroxide into the microscopic voids of the carbon material for etching to create more voids comprises:
s021: preparing a mixed solution containing the alkali metal hydroxide and the carbon material;
s022: ball milling the mixed solution, and then drying to obtain mixed powder;
s023: and heating the mixed powder to perform etching reaction.
In the solution state, the alkali metal hydroxide and the carbon material can be better dissolved and blended, and meanwhile, the metal hydroxide can be more fully contacted with the carbon material and enter microscopic gaps of the carbon material through ball milling treatment, so that the mixed powder obtained after drying can be more fully subjected to etching reaction.
Further, the step of preparing a mixed solution containing the alkali metal hydroxide and the carbon material may include: dissolving alkali metal hydroxide in water to obtain alkali liquor, and then adding carbon material to dissolve to obtain mixed solution. In the mixed solution, the concentration of alkali metal hydroxide is 1-6 mol/L; if the concentration of the alkali metal hydroxide is too low, the water solvent is too much, the subsequent drying and solvent removing time is long, the difficulty of forming carbon material-alkali metal hydroxide mixed powder is high, the concentration of the alkali metal hydroxide is too high, the alkali liquor can not completely submerge the carbon material, and the carbon material and the alkali metal hydroxide are insufficiently mixed to influence the subsequent etching reaction.
Further, the mass ratio of the alkali metal hydroxide to the carbon material is 1:0.8-3; the proportion of the alkali metal hydroxide is too small, the etching effect on the carbon material is not ideal, the proportion is too large, the consumption of the alkali metal hydroxide is large, the cost is increased, and the environment is not friendly.
Further, the ball milling process includes the steps of: and adding zirconium beads into the mixed solution, and performing ball milling at a rotating speed of 500-1500 rpm. Specifically, ball milling may be performed in a ball milling tank.
In one embodiment, the weight ratio of the carbon material to the zirconium beads is in the range of 1:50-300, the ratio of the carbon material is too high, the ball milling effect is not ideal, the ratio of the carbon material is too low, the synthesis efficiency is low, and the industrialization is not facilitated. Further, the zirconium beads comprise zirconium beads with the particle sizes of 5mm and 0.6mm, the proportion of the two sizes of the 5mm and the 0.6mm is in the range of 1:5-20, the 5mm zirconium beads serve to agitate the carbon material of the ball milling tank, the carbon material is prevented from being aggregated in the tank to form blocks, the ball milling effect is affected, and the 0.6mm zirconium beads serve to grind the carbon material into particles with smaller particle sizes, so that the carbon material is favorably stripped by a follow-up etching agent. The ratio of the 5mm zirconium beads to the 0.6mm zirconium beads is too large, and the ball milling effect is not ideal; if the ratio is too small, the carbon material tends to aggregate into a block. The ball milling rotating speed is too low, the ball milling efficiency is low, and the synthesis period is prolonged; the rotating speed is too high, the ball milling rapidly generates a large amount of heat, the temperature of the system is increased drastically, and meanwhile, the energy consumption and the cost in the production process are increased.
Further, the ball milling time ranges from 10 minutes to 30 minutes, the ball milling time is too short, and the particle size of the carbon material is too large, so that the subsequent production is not facilitated; the ball milling time is too long, the production period is long, and the industrial production is not facilitated.
Further, the etching reaction is performed in an inert atmosphere, and concretely can be inert gases such as nitrogen, argon and the like; the etching reaction can be carried out in a muffle furnace, the mixed powder is transferred into the tubular muffle furnace, and nitrogen or inert gas is continuously introduced to remove air in the furnace; and then heating to perform etching reaction. The flow rate of the nitrogen or the inert gas in the tubular furnace ranges from 0.5L/min to 3L/min, the flow rate of the nitrogen or the inert gas is too low, the time for exhausting air in the furnace body is longer, and the production efficiency is lower; too high a flow rate, part of the mixed powder is blown off by the gas flow and results in a decrease in yield. Further, the temperature of the etching reaction is 500-900 ℃; the etching reaction temperature is too low, the etching rate of the carbon material is slow, the reaction process is slow, the production period is long, the etching reaction temperature is too high, the energy consumption is increased, and the production cost is increased. The etching reaction time is 10-30 min, the reaction time is too short, and the carbon material is insufficiently etched and is not produced subsequently; the etching time is too long, the production efficiency is reduced, and the production cost is increased.
In the above step S03, the peeling may be ultrasonic peeling, and specifically, the step of ultrasonic peeling treatment includes: and dissolving the etched carbon material in a solvent, performing ultrasonic dispersion, and then removing the solvent.
The solvent may be water. Adding water into the etched carbon material, stirring and filtering the mixture, and removing excessive alkali metal hydroxide and reaction product alkali carbonate in the carbon material. The concentration of the etched carbon material after being dissolved in the solvent is 10-300 mg/ml, the concentration of the carbon material is too high in the ultrasonic process, the carbon material is difficult to be uniformly dispersed in water, and the ultrasonic stripping difficulty is high; the concentration is too low, and the ultrasonic stripping efficiency is low. The ultrasonic dispersion time is 60-120 min, the time is too short, a large amount of large-particle-size products are not dispersed, the synthesis yield is low, the ultrasonic time is too long, the synthesis period is long, and the synthesis efficiency is low.
The step of desolvating may include: transferring the liquid after ultrasonic dispersion into a centrifuge tube, centrifuging at 8000rpm for 5min (removing particles with larger particle size which are not separated and can cause the reduction of the photoelectric performance of a final sample, then collecting the upper liquid of the centrifuge tube, transferring the upper liquid into a dialysis bag with cutoff of 1000, dialyzing the upper liquid in deionized water at 80 ℃ for 24h, transferring the purified carbon quantum dot solution into a vacuum drying oven, and drying for 24h to obtain the initial carbon quantum dots.
Further, the step of water vapor treatment includes: and placing the product after ultrasonic stripping treatment in inert atmosphere, and then introducing steam for reaction. Steam reacts with the carbon material at high temperature, sp 3 More sp of hybridization carbon atom reactivity 2 The hybridized carbon atoms are high, and the hybridized carbon atoms react with water vapor preferentially at high temperature. By utilizing the characteristic, sp in the carbon quantum dots can be effectively removed by controlling the reaction time 3 And the carbon atoms are hybridized, so that the carrier mobility of the material is improved. The water vapor treatment is carried out in an inert atmosphere, specifically, the initial quantum dots are placed in a tube furnace, nitrogen or inert gas is introduced, the flow rate of the nitrogen or the inert gas in the tube furnace ranges from 0.5L/min to 3L/min, the flow rate of the nitrogen or the inert gas is too low, the time for exhausting air in the furnace body is long, and the production efficiency is low. Too high a flow rate, part of the carbon quantum dot material is blown away by the gas flow, and results in a decrease in yield. The reaction temperature of the water vapor is 600-800 ℃, the reaction temperature is too low, and the reaction of the water vapor and the carbon quantum dots is difficult to carry out. The reaction temperature is too high, the production energy consumption is increased, and the cost is increasedThe method comprises the steps of carrying out a first treatment on the surface of the The reaction time of the water vapor ranges from 30 minutes to 90 minutes, and the sp in the carbon quantum dot material can not be completely removed due to the too short reaction time 3 Hybridization of carbon atoms, too long a reaction time, partial sp 2 The hybridized carbon atoms are etched by water vapor, affecting the yield of the material.
On the other hand, the embodiment of the invention also provides a carbon quantum dot, which is prepared by the preparation method of the carbon quantum dot.
The carbon quantum dot provided by the embodiment of the invention is prepared by the preparation method of the carbon quantum dot special to the embodiment of the invention, and the carbon quantum dot has more sp 2 The carbon atoms are hybridized, so that the carrier mobility of the carbon atoms can be improved, and the photoelectric performance is good.
In a specific embodiment, a method for preparing a carbon quantum dot includes the following steps:
(1) Etching process of carbon material
A: weighing a certain amount of potassium hydroxide, and adding the potassium hydroxide into deionized water to prepare a potassium hydroxide aqueous solution with a certain concentration. And then, sequentially adding a certain amount of potassium hydroxide solution, carbon materials and zirconium beads into a ball milling tank, and fixing the ball milling tank on a ball mill to ensure good sealing performance of the ball milling tank. The ball mill is then started and run at a constant rotational speed for a period of time to ensure that the carbon material is thoroughly ground and uniformly mixed with potassium hydroxide. After the ball milling tank is cooled to room temperature, transferring the mixture in the ball milling tank to a 325-mesh screen, and sieving to remove zirconium beads and carbon material particles with larger particle size, thereby obtaining uniform carbon material-potassium hydroxide mixed solution.
B: and (3) transferring the carbon material-potassium hydroxide mixed solution in the step A into a drying oven at 110 ℃ for baking, removing the moisture in the mixed solution, and obtaining the carbon material-potassium hydroxide mixed powder.
C: transferring the carbon material-potassium hydroxide mixed powder in the step B into a tubular muffle furnace, continuously introducing protective gas for 30min, and removing air in the furnace. Then, heating to a preset temperature under a protective atmosphere, carrying out constant-temperature etching reaction for a period of time, and after the reaction is finished, bringing the furnace temperature to room temperature and taking out a reaction product.
(2) Stripping and purifying process of carbon quantum dots
The etched carbon material was removed from the furnace and transferred to a beaker, 500ml deionized water was added, and after stirring for 30min, the filter residue was filtered and collected. Next, the filter residue was transferred to a beaker, a certain amount of water was added, and sonicated for a period of time. After the sonication was completed, the liquid was transferred to a centrifuge tube and centrifuged at 8000rpm for 5min. Then, collecting the upper liquid of the centrifuge tube, transferring to a dialysis bag with cutoff rate of 1000, and dialyzing in deionized water at 80 ℃ for 24 hours; transferring the purified carbon quantum dot solution to a vacuum drying oven, and drying for 24 hours to obtain the initial carbon quantum dot.
(3) Post-treatment process of initial carbon quantum dot material
Transferring the initial carbon quantum dots obtained in the step (2) into a tubular muffle furnace, continuously introducing protective gas for 30min, and removing air in the furnace body. Then, the furnace body is heated to a preset temperature under a protective atmosphere. Then, switching the gas path of the protective gas to enable the protective gas to pass through a safety bottle filled with deionized water, loading water vapor into the tubular furnace, and reacting with carbon quantum dots in the furnace. And after the reaction is finished, the furnace temperature is changed to room temperature, and the carbon quantum dot material with excellent performance is obtained.
According to the preparation method of the carbon quantum dot, firstly, the alkali metal hydroxide is used for etching the carbon material, a large number of pores are generated in the carbon material, the microstructure of the material is damaged, then, the microscopic framework of the carbon material is collapsed through ultrasonic treatment, the carbon quantum dot is produced by tearing, finally, the carbon quantum dot is treated by adopting water vapor at high temperature, sp2 hybridization and sp3 hybridization carbon atom reactivity difference are utilized, sp3 hybridization carbon atoms in the carbon quantum dot material are removed, and carrier mobility of the carbon quantum dot is improved, so that the finally obtained carbon quantum dot has good photoelectric performance. The preparation method is simple to operate, low in cost and environment-friendly, and is suitable for industrial application.
According to the preparation method of the carbon quantum dot, the carbon quantum dot with excellent photoelectric performance is prepared by adopting a conventional carbon material as a raw material through operations such as etching, dispersing, collecting, post-treatment and the like.
The invention has been tested several times in succession, and the invention will now be described in further detail with reference to a few test results, which are described in detail below in connection with specific examples.
Example 1
The preparation method of the carbon quantum dot comprises the following steps:
(1) Etching of carbon materials
Step A: 56g of potassium hydroxide was weighed and added to 250ml of deionized water to prepare a 4M aqueous potassium hydroxide solution. Subsequently, 250ml of potassium hydroxide solution, 100g of carbon black, and 2kg of zirconium beads (200 g of zirconium beads having a particle diameter of 5mm, 1800g of zirconium beads having a particle diameter of 0.6 mm) were sequentially added to a ball mill pot, and the ball mill pot was fixed to a ball mill, thereby ensuring good sealability of the ball mill pot. Then, the ball mill was started and ball milled at 1200rpm for 20min to ensure that the carbon material was well milled and mixed with potassium hydroxide. After the ball milling tank is cooled to room temperature, transferring the mixture in the ball milling tank to a 325-mesh screen, and sieving to remove zirconium beads and carbon material particles with larger particle size, thereby obtaining uniform carbon black-potassium hydroxide mixed solution.
And (B) step (B): and C, transferring the carbon black-potassium hydroxide mixed solution in the step A to a drying oven at 110 ℃ for baking, removing the moisture in the mixed solution, and obtaining the carbon black-potassium hydroxide mixed powder.
Step C: and C, transferring the carbon black-potassium hydroxide mixed powder in the step B into a tubular muffle furnace, continuously introducing argon for 30min at a flow rate of 0.8L/min, and removing air in the furnace body. Then, the temperature is raised to 700 ℃ under the argon atmosphere, the constant temperature etching is carried out for 30min, after the reaction is finished, the furnace temperature is brought to room temperature, and the reaction product is taken out.
(2) Stripping and purification of carbon quantum dots
The etched carbon black was taken out of the furnace body and transferred to a beaker with a capacity of 1L, 500ml of deionized water was added, and after stirring for 30min, the filter residue was filtered and collected. Then, the filter residue is transferred to a beaker with the capacity of 2L, 1L of deionized water is added, ultrasonic treatment is carried out for 90min, and the etched carbon black is peeled into carbon quantum dots. After the completion of the sonication, the liquid was transferred to a 50ml centrifuge tube, centrifuged at 8000rpm for 5min, and the lower pellet was removed. Then, collecting the upper liquid of the centrifuge tube, transferring to a dialysis bag with cutoff rate of 1000, and dialyzing in deionized water at 80 ℃ for 24 hours; and finally, transferring the purified carbon quantum dot solution to a vacuum drying oven, and drying for 24 hours to obtain the initial carbon quantum dot.
(3) Post-treatment of carbon quantum dots
Transferring the obtained initial carbon quantum dots into a tubular muffle furnace, continuously introducing argon for 30min at a flow rate of 0.8L/min, and removing air in the furnace body. Then, the furnace was warmed to 800 ℃ under an argon atmosphere. Then, switching the gas path of argon, leading the argon to pass through a safety bottle filled with deionized water, loading water vapor into a tube furnace, and reacting with carbon quantum dots in the furnace for 60min. And after the reaction is finished, the furnace temperature is changed to room temperature, and the carbon quantum dot material with excellent performance is obtained.
Example 2
The preparation method of the carbon quantum dot comprises the following steps:
(1) Etching of carbon materials
Step A: 56g of potassium hydroxide was weighed and added to 250ml of deionized water to prepare a 4M aqueous potassium hydroxide solution. Subsequently, 250ml of potassium hydroxide solution, 100g of charcoal, and 2kg of zirconium beads (200 g of zirconium beads having a particle size of 5mm, 1800g of zirconium beads having a particle size of 0.6 mm) were sequentially added to a ball mill pot, and the ball mill pot was fixed to a ball mill, thereby ensuring good sealability of the ball mill pot. Then, the ball mill was started and ball milled at 1200rpm for 20min to ensure that the carbon material was well milled and mixed with potassium hydroxide. After the ball milling tank is cooled to room temperature, transferring the mixture in the ball milling tank to a 325-mesh screen, and sieving to remove zirconium beads and carbon material particles with larger particle size, thereby obtaining uniform charcoal-potassium hydroxide mixed solution.
And (B) step (B): and C, transferring the charcoal-potassium hydroxide mixed solution in the step A to a drying oven at 110 ℃ for baking, removing water in the mixed solution, and obtaining charcoal-potassium hydroxide mixed powder.
Step C: transferring the charcoal-potassium hydroxide mixed powder in the step B into a tubular muffle furnace, continuously introducing argon for 30min at a flow rate of 0.8L/min, and removing air in the furnace body. Then, the temperature is raised to 700 ℃ under the argon atmosphere, the constant temperature etching is carried out for 30min, after the reaction is finished, the furnace temperature is brought to room temperature, and the reaction product is taken out.
(2) Stripping and purification of carbon quantum dots
The etched charcoal was removed from the oven and transferred to a beaker with a capacity of 1L, 500ml of deionized water was added, and after stirring for 30min, the filter residue was filtered and collected. Then, the filter residue is transferred to a beaker with the capacity of 2L, 1L of deionized water is added, ultrasonic treatment is carried out for 90min, and the etched carbon black is peeled into carbon quantum dots. After the completion of the sonication, the liquid was transferred to a 50ml centrifuge tube, centrifuged at 8000rpm for 5min, and the lower pellet was removed. Then, collecting the upper liquid of the centrifuge tube, transferring to a dialysis bag with cutoff rate of 1000, and dialyzing in deionized water at 80 ℃ for 24 hours; and finally, transferring the purified carbon quantum dot solution to a vacuum drying oven, and drying for 24 hours to obtain the initial carbon quantum dot.
(3) Post-treatment of carbon quantum dots
Transferring the obtained initial carbon quantum dots into a tubular muffle furnace, continuously introducing argon for 30min at a flow rate of 0.8L/min, and removing air in the furnace body. Then, the furnace was warmed to 800 ℃ under an argon atmosphere. Then, switching the gas path of argon, leading the argon to pass through a safety bottle filled with deionized water, loading water vapor into a tube furnace, and reacting with carbon quantum dots in the furnace for 60min. And after the reaction is finished, the furnace temperature is changed to room temperature, and the carbon quantum dot material with excellent performance is obtained.
Example 3
The preparation method of the carbon quantum dot comprises the following steps:
(1) Etching of carbon materials
Step A: 40g of sodium hydroxide was weighed and added to 250ml of deionized water to prepare a 4M aqueous sodium hydroxide solution. Subsequently, 250ml of sodium hydroxide solution, 100g of carbon black, and 2kg of zirconium beads (200 g of zirconium beads having a particle diameter of 5mm, 1800g of zirconium beads having a particle diameter of 0.6 mm) were sequentially added to a ball mill pot, and the ball mill pot was fixed to a ball mill, thereby ensuring good sealing of the ball mill pot. Then, the ball mill was started and ball milled at 1200rpm for 20min to ensure that the carbon material was well-milled and uniformly mixed with sodium hydroxide. After the ball milling tank is cooled to room temperature, transferring the mixture in the ball milling tank to a 325-mesh screen, and sieving to remove zirconium beads and carbon material particles with larger particle size, thereby obtaining uniform carbon black-sodium hydroxide mixed solution.
And (B) step (B): and C, transferring the carbon black-sodium hydroxide mixed solution in the step A to a drying oven at 110 ℃ for baking, removing the moisture in the mixed solution, and obtaining the carbon black-sodium hydroxide mixed powder.
Step C: and C, transferring the carbon black-sodium hydroxide mixed powder in the step B into a tubular muffle furnace, continuously introducing argon for 30min at a flow rate of 0.8L/min, and removing air in the furnace body. Then, the temperature is raised to 700 ℃ under the argon atmosphere, the constant temperature etching is carried out for 30min, after the reaction is finished, the furnace temperature is brought to room temperature, and the reaction product is taken out.
(2) Stripping and purification of carbon quantum dots
The etched carbon black was taken out of the furnace body and transferred to a beaker with a capacity of 1L, 500ml of deionized water was added, and after stirring for 30min, the filter residue was filtered and collected. Then, the filter residue is transferred to a beaker with the capacity of 2L, 1L of deionized water is added, ultrasonic treatment is carried out for 90min, and the etched carbon black is peeled into carbon quantum dots. After the completion of the sonication, the liquid was transferred to a 50ml centrifuge tube, centrifuged at 8000rpm for 5min, and the lower pellet was removed. Then, collecting the upper liquid of the centrifuge tube, transferring to a dialysis bag with cutoff rate of 1000, and dialyzing in deionized water at 80 ℃ for 24 hours; and finally, transferring the purified carbon quantum dot solution to a vacuum drying oven, and drying for 24 hours to obtain the initial carbon quantum dot.
(3) Post-treatment of carbon quantum dots
Transferring the obtained initial carbon quantum dots into a tubular muffle furnace, continuously introducing argon for 30min at a flow rate of 0.8L/min, and removing air in the furnace body. Then, the furnace was warmed to 800 ℃ under an argon atmosphere. Then, switching the gas path of argon, leading the argon to pass through a safety bottle filled with deionized water, loading water vapor into a tube furnace, and reacting with carbon quantum dots in the furnace for 60min. And after the reaction is finished, the furnace temperature is changed to room temperature, and the carbon quantum dot material with excellent performance is obtained.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (10)
1. The preparation method of the carbon quantum dot is characterized by comprising the following steps of:
providing a carbon material selected from at least one of carbon black, charcoal, coke, and activated carbon;
etching the carbon material by using alkali metal hydroxide to obtain an etched carbon material; wherein the mass ratio of the alkali metal hydroxide to the carbon material is 1:0.8-3; the etching treatment comprises the following steps: preparing a mixed solution containing the alkali metal hydroxide and the carbon material; ball milling the mixed solution, and then drying to obtain mixed powder; heating the mixed powder to perform etching reaction;
stripping the etched carbon material, and then removing sp in the carbon material by steam treatment of a product obtained after stripping 3 Hybridizing carbon atoms to obtain the carbon quantum dots; wherein the step of water vapor treatment comprises: and placing the stripped product in an inert atmosphere, and then introducing water vapor for reaction, wherein the temperature of the water vapor reaction is 600-800 ℃.
2. The method for preparing carbon quantum dots according to claim 1, wherein the alkali metal hydroxide is at least one selected from the group consisting of lithium hydroxide, sodium hydroxide and potassium hydroxide.
3. The method for preparing carbon quantum dots according to claim 1, wherein the concentration of the alkali metal hydroxide in the mixed solution is 1-6 mol/L.
4. The method for preparing carbon quantum dots according to claim 1, wherein the step of ball milling treatment comprises: and adding zirconium beads into the mixed solution, and performing ball milling at a rotating speed of 500-1500 rpm.
5. The method for preparing carbon quantum dots according to claim 1, wherein the etching reaction is performed in an inert atmosphere.
6. The method for preparing the carbon quantum dots according to claim 1, wherein the temperature of the etching reaction is 500-900 ℃; and/or the number of the groups of groups,
the etching reaction time is 10-30 min.
7. The method of preparing carbon quantum dots of claim 1, wherein the step of stripping comprises: and dissolving the etched carbon material in a solvent, performing ultrasonic dispersion, and then removing the solvent.
8. The method for preparing carbon quantum dots according to claim 7, wherein the concentration of the etched carbon material after being dissolved in a solvent is 10-300 mg/ml; and/or the number of the groups of groups,
the solvent is water.
9. The method for preparing carbon quantum dots according to claim 7, wherein the ultrasonic dispersion time is 60-120 min.
10. The method for preparing carbon quantum dots according to any one of claims 1 to 9, wherein the water vapor reaction time is 30 to 90 minutes.
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| CN108394886A (en) * | 2018-04-03 | 2018-08-14 | 中国工程物理研究院材料研究所 | A kind of method, its product and application preparing carbon quantum dot based on highly basic cutting graphite oxide |
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| CN108394886A (en) * | 2018-04-03 | 2018-08-14 | 中国工程物理研究院材料研究所 | A kind of method, its product and application preparing carbon quantum dot based on highly basic cutting graphite oxide |
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