阅读说明：本技术 一种碳量子点气敏传感材料及其制备方法和应用 (Carbon quantum dot gas-sensitive sensing material and preparation method and application thereof ) 是由 吴钊峰 孟彪 王龙 曹帅 许同洲 张宇智 于 2021-08-30 设计创作，主要内容包括：本发明提供了一种碳量子点气敏传感材料及其制备方法和应用,属于纳米材料制备技术领域。具体为以下步骤：将废旧棉花、水和浓硫酸混合后进行水热反应,得到上层液体,所述浓硫酸的质量分数为98％；将所述上层液体进行离心,得到所述碳量子点气敏传感材料。本发明以废旧棉花为原料,利用简单的一步水热法制备出粒径较为均匀,具有优异荧光性能的碳量子点分散液,以浓硫酸为催化剂,不需要经过过滤和透析袋透析,可以直接将碳量子点分散液涂敷在电极片上,待其干燥后作为传感芯片,用来检测空气中的有毒有害气体。本发明采用废旧棉花为原料,并且有效简化了碳量子点的制备过程,拓展了碳量子点的应用领域,降低了成本。(The invention provides a carbon quantum dot gas-sensitive sensing material and a preparation method and application thereof, belonging to the technical field of nano material preparation. The method comprises the following steps: mixing waste cotton, water and concentrated sulfuric acid, and then carrying out hydrothermal reaction to obtain upper-layer liquid, wherein the mass fraction of the concentrated sulfuric acid is 98%; and centrifuging the upper layer liquid to obtain the carbon quantum dot gas-sensitive sensing material. The carbon quantum dot dispersion liquid with uniform particle size and excellent fluorescence property is prepared by using waste cotton as a raw material and utilizing a simple one-step hydrothermal method, concentrated sulfuric acid is used as a catalyst, the carbon quantum dot dispersion liquid can be directly coated on an electrode sheet without being filtered and dialyzed by a dialysis bag, and the carbon quantum dot dispersion liquid is used as a sensing chip after being dried and is used for detecting toxic and harmful gases in the air. The method adopts the waste cotton as the raw material, effectively simplifies the preparation process of the carbon quantum dots, expands the application field of the carbon quantum dots and reduces the cost.)

1. A preparation method of a carbon quantum dot gas-sensitive sensing material is characterized by comprising the following steps:

mixing waste cotton, water and concentrated sulfuric acid, and then carrying out hydrothermal reaction to obtain upper-layer liquid, wherein the mass fraction of the concentrated sulfuric acid is 98%;

and centrifuging the upper layer liquid to obtain the carbon quantum dot gas-sensitive sensing material.

2. The preparation method according to claim 1, wherein the using ratio of the waste cotton to the water to the concentrated sulfuric acid is 20-400 mg: 20-40 mL: 0.25-2 mL.

3. The preparation method according to claim 3, wherein the ratio of the used cotton, water and concentrated sulfuric acid is 400 mg: 40mL of: 2 mL.

4. The preparation method according to claim 1 or 2, wherein the hydrothermal reaction is carried out at a temperature of 120 to 180 ℃ for 6 to 12 hours.

5. The preparation method according to claim 4, wherein the temperature of the hydrothermal reaction is 180 ℃ and the time is 8 h.

6. The method according to claim 1, wherein the centrifugation is performed at 10000r/min for 3-5 min.

7. The carbon quantum dot gas-sensitive sensing material prepared by the preparation method of any one of claims 1 to 6.

8. The carbon quantum dot gas-sensitive sensing material according to claim 7, wherein the amount of the carbon quantum dot gas-sensitive sensing material with the particle size of 1-3 nm is 75-80%.

9. The use of the carbon quantum dot gas-sensitive sensing material according to claim 7 or 8 in the field of gas sensing.

Technical Field

The invention relates to the technical field of nano material preparation, in particular to a carbon quantum dot gas-sensitive sensing material and a preparation method and application thereof.

Background

Carbon quantum dot materials are a new type of carbon nano-materials developed in recent years, and have been widely used in the fields of biological imaging, biosensors, light emitting diodes, and the like. The preparation process and method of the carbon quantum dot have various types, and common processes include an arc discharge method, a laser ablation method, an electrochemical method, a strong acid oxidation method and the like. The hydrothermal method is a commonly used method for preparing carbon quantum dots, and refers to a method for preparing carbon quantum dots by treating precursors of carbon quantum dots under appropriate conditions and then performing hydrothermal reaction.

Some researchers find that carbon quantum dots such as orange peel, eggs, cotton and the like can be prepared directly by using food, beverages and the like which are visible everywhere in daily life, but cellulose filter paper is required to be used for filtering after the carbon quantum dot dispersion liquid prepared in the prior art is prepared, and then dialysis is carried out by using a dialysis bag, so that relatively pure carbon quantum dots are obtained. Therefore, the process flow of the carbon quantum dot preparation is increased, more time is consumed, and the cost of the carbon quantum dot preparation is greatly increased.

Disclosure of Invention

In view of the above, the present invention aims to provide a carbon quantum dot gas sensitive sensing material, and a preparation method and an application thereof. The preparation method has simple process and low production cost.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a preparation method of a carbon quantum dot gas-sensitive sensing material, which comprises the following steps:

mixing waste cotton, water and concentrated sulfuric acid, and then carrying out hydrothermal reaction to obtain upper-layer liquid, wherein the mass fraction of the concentrated sulfuric acid is 98%;

and centrifuging the upper layer liquid to obtain the carbon quantum dot gas-sensitive sensing material.

Preferably, the using amount ratio of the waste cotton to the water to the concentrated sulfuric acid is 20-400 mg: 20-40 mL: 0.25-2 mL.

Preferably, the using ratio of the waste cotton to the water to the concentrated sulfuric acid is 400 mg: 40mL of: 2 mL.

Preferably, the temperature of the hydrothermal reaction is 120-180 ℃ and the time is 6-12 h.

Preferably, the temperature of the hydrothermal reaction is 180 ℃ and the time is 8 h.

Preferably, the rotating speed of the centrifugation is 10000r/min, and the time is 3-5 min.

The invention also provides the carbon quantum dot gas-sensitive sensing material prepared by the preparation method in the technical scheme.

Preferably, the number of the carbon quantum dot gas-sensitive sensing material with the particle size of 1-3 nm is 75-80%.

The invention also provides application of the carbon quantum dot gas-sensitive sensing material in the technical scheme in the field of gas-sensitive sensing.

The invention provides a preparation method of a carbon quantum dot gas-sensitive sensing material, which comprises the following steps: mixing waste cotton, water and concentrated sulfuric acid, and then carrying out hydrothermal reaction to obtain upper-layer liquid, wherein the mass fraction of the concentrated sulfuric acid is 98%; and centrifuging the upper layer liquid to obtain the carbon quantum dot gas-sensitive sensing material. The carbon quantum dot dispersion liquid with uniform particle size and excellent fluorescence property is prepared by using waste cotton as a raw material and utilizing a simple one-step hydrothermal method, concentrated sulfuric acid is used as a catalyst, the carbon quantum dot dispersion liquid can be directly coated on an electrode sheet without being filtered and dialyzed by a dialysis bag, and the carbon quantum dot dispersion liquid is used as a sensing chip after being dried and is used for detecting toxic and harmful gases in the air. The method adopts the waste cotton as the raw material, effectively simplifies the preparation process of the carbon quantum dots, expands the application field of the carbon quantum dots and reduces the cost.

Drawings

FIG. 1 is a Transmission Electron Microscope (TEM) image of carbon quantum dots prepared in example 1 at different magnifications;

FIG. 2 is a statistical graph of the particle size distribution of carbon quantum dots obtained in example 1;

FIG. 3 is a graph showing the UV and VIS absorption of the carbon quantum dot dispersion prepared in example 1;

FIG. 4 is a graph of IR spectroscopy analysis of carbon quantum dots obtained in example 1;

FIG. 5 is a Raman spectrum of the carbon quantum dots obtained in example 1;

FIG. 6 is an X-ray diffraction (XRD) spectrum of the carbon quantum dots prepared in example 1;

FIG. 7 is a fluorescence spectrum of a carbon quantum dot dispersion prepared in example 1;

FIG. 8 is a gas-sensitive response curve of carbon quantum dots prepared in example 1 to ammonia gas;

fig. 9 is a gas-sensitive response curve of carbon quantum dots prepared in example 1 to hydrogen peroxide vapor.

Detailed Description

The invention provides a preparation method of a carbon quantum dot gas-sensitive sensing material, which comprises the following steps:

mixing waste cotton, water and concentrated sulfuric acid, and then carrying out hydrothermal reaction to obtain upper-layer liquid, wherein the mass fraction of the concentrated sulfuric acid is 98%;

and centrifuging the upper layer liquid to obtain the carbon quantum dot gas-sensitive sensing material.

The method comprises the steps of mixing waste cotton, water and concentrated sulfuric acid, and then carrying out hydrothermal reaction to obtain upper-layer liquid, wherein the mass fraction of the concentrated sulfuric acid is 98%.

In the invention, the dosage ratio of the waste cotton, water and concentrated sulfuric acid is preferably 20-400 mg: 20-40 mL: 0.25-2 mL, more preferably 400 mg: 40mL of: 2 mL.

In the invention, the temperature of the hydrothermal reaction is preferably 120-180 ℃, more preferably 180 ℃, and the time is preferably 6-12 h, more preferably 8-12 h.

In the invention, the waste cotton is preferably washed by tap water and dried for standby.

In the present invention, the hydrothermal reaction is preferably carried out in an autoclave.

After the hydrothermal reaction is finished, the obtained hydrothermal reaction product is preferably naturally cooled to room temperature, and then the autoclave is taken out and kept stand to obtain the upper-layer liquid.

After the upper layer liquid is obtained, the upper layer liquid is centrifuged to obtain the carbon quantum dot gas-sensitive sensing material.

In the invention, the rotation speed of the centrifugation is preferably 10000r/min, and the time is preferably 3-5 min.

The invention also provides the carbon quantum dot gas-sensitive sensing material prepared by the preparation method in the technical scheme.

In the invention, the number of the carbon quantum dot gas-sensitive sensing material with the particle size of 1-3 nm is preferably 75-80%.

The invention also provides application of the carbon quantum dot gas-sensitive sensing material in the technical scheme in the field of gas-sensitive sensing.

The carbon quantum dot gas-sensitive sensing material is preferably coated on an electrode sheet, and is dried to be used as a sensing chip for detecting toxic and harmful gases in the air.

In the present invention, the application preferably comprises detecting ammonia and hydrogen peroxide vapor.

In order to further illustrate the present invention, the carbon quantum dot gas-sensitive sensing material provided by the present invention, the preparation method and the application thereof are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.

Example 1

Placing 400mg of cotton, 40mL of deionized water and 2mL of concentrated sulfuric acid with the mass concentration of 98% in an autoclave, then placing the autoclave filled with experimental raw materials in an electric heating constant-temperature air-blowing drying box, setting the reaction time to be 6h, setting the reaction temperature to be 120 ℃, after the reaction is finished, cooling to room temperature, taking out the autoclave, opening the cooled autoclave, taking out the upper layer liquid of a reaction product, putting the upper layer liquid into a centrifuge tube, placing the centrifuge tube in a centrifuge with the rotation speed of 10000r/min, centrifuging for 5min, and removing precipitates in the centrifuge tube after the centrifugation is finished, thus obtaining the carbon quantum dot gas-sensitive sensing material.

Example 2

Placing 400mg of cotton, 40mL of deionized water and 2mL of concentrated sulfuric acid with the mass concentration of 98% in an autoclave, then placing the autoclave filled with experimental raw materials in an electric heating constant-temperature air-blowing drying box, setting the reaction time to be 12h, setting the reaction temperature to be 180 ℃, after the reaction is finished, cooling to room temperature, taking out the autoclave, opening the cooled autoclave, taking out the upper layer liquid of a reaction product, putting the upper layer liquid into a centrifuge tube, placing the centrifuge tube in a centrifuge with the rotation speed of 10000r/min, centrifuging for 5min, and removing precipitates in the centrifuge tube after the centrifugation is finished, thus obtaining the carbon quantum dot gas-sensitive sensing material.

Example 3

200mg of cotton, 20mL of deionized water and 0.25mL of concentrated sulfuric acid with the mass concentration of 98% are placed in an autoclave, then the autoclave filled with experimental raw materials is placed in an electric heating constant-temperature air-blowing drying oven, the reaction time is set to 6h, the reaction temperature is set to 120 ℃, after the reaction is finished, the autoclave is cooled to room temperature, the autoclave is taken out, the cooled autoclave is opened, the upper layer liquid of a reaction product is taken out and put into a centrifuge tube, the centrifuge tube is placed in a centrifuge with the rotation speed of 10000r/min, the centrifuge tube is centrifuged for 5min, and after the centrifugation is finished, precipitates in the centrifuge tube are removed, so that the carbon quantum dot gas-sensitive sensing material is obtained.

Example 4

Placing 20mg of cotton, 20mL of deionized water and 0.25mL of concentrated sulfuric acid with the mass concentration of 98% in an autoclave, then placing the autoclave filled with experimental raw materials in an electric heating constant-temperature air-blowing drying box, setting the reaction time to be 12h, setting the reaction temperature to be 180 ℃, after the reaction is finished, cooling to room temperature, taking out the autoclave, opening the cooled autoclave, taking out the upper-layer liquid of the reaction product, putting the upper-layer liquid into a centrifuge tube, placing the centrifuge tube in a centrifuge with the rotation speed of 10000r/min, centrifuging for 5min, and removing precipitates in the centrifuge tube after the centrifugation is finished, thus obtaining the carbon quantum dot gas-sensitive sensing material.

The sample obtained in example 1 was observed by a transmission electron microscope, and as shown in FIG. 1, (a), (b), (c), and (d) were each observedShould be at a magnification of 8 × 10⁵、4×10⁵、2×10⁵、1×10⁵According to a transmission electron microscope image of the lower carbon quantum dot, statistics is carried out on the particle size distribution of 165 carbon quantum dots according to (c) in fig. 1, and the statistical result in fig. 2 shows that 78% of the carbon quantum dots are concentrated in 1-3 nm in size, which indicates that the carbon quantum dots prepared by the method are uniform in size.

Sample Properties

The carbon quantum dots prepared by the hydrothermal method of example 1 were subjected to a liquid uv test, see fig. 3, and it can be seen from fig. 3 that the cotton-based carbon quantum dots prepared by the hydrothermal method show strong absorption in the uv region (< 400), while they show only a certain amount of absorption in the visible region.

Infrared spectroscopic analysis was performed on the carbon quantum dots prepared in example 1, and the analysis result is shown in FIG. 4, from which it can be seen that the absorption peak is 3342cm^-1The focus here indicates the presence of an O-H bond. And 2912cm^-1The absorption peak at this point corresponds to the C-H bond. At 1170cm^-1The strong absorption peak appears there is due to the stretching vibration of C ═ O.

Raman spectroscopy was performed on the carbon quantum dots of example 1. As shown in fig. 5, the test result of fig. 5 shows that the raman spectrum of the cotton-based carbon quantum dot prepared by the hydrothermal method has no two carbon peaks, so that it can be known that the structure of the cotton-based carbon quantum dot is different from that of graphene. The absence of two characteristic peaks is because the emission of carbon quantum dots masks the characteristic peaks of carbon. We calculated the peak value of the cotton-based carbon quantum dots, and found that it was 2800cm^-1Nearby, the size is close to 12 k.

The sample of example 1 was analyzed by X-ray diffraction (XRD test), and as shown in fig. 6, it can be seen that the sample has a diffraction broad peak at 24 °, which is consistent with the graphite structure.

The carbon quantum dots prepared in example 1 were detected by an instrument F-4500FL spectrophotometer, and the structure is shown in FIG. 7. Firstly, a small amount of carbon quantum dot solution is transferred and put into a cuvette, and then the cuvette is put into a testing instrument and covered with a shading cover. From the test results of fig. 7, it can be seen that the fluorescence response intensity of the cotton-based carbon quantum dot reaches a peak value near the wavelength of 530nm, and the final peak value reaches about 1.5 k.

The gas-sensitive sensing performance of the carbon quantum dots prepared in example 1 was tested by the following specific steps: and (3) taking the carbon quantum dot dispersion liquid, dropwise adding the carbon quantum dot dispersion liquid onto the silver interdigital electrode sheet, and standing and drying the silver interdigital electrode sheet at room temperature for 24 hours. After drying, applying 4V voltage to two ends of electrode plate, electrifying and ageing for 12 hr, and testing 100ppm NH₃The gas sensitive test was performed, and the gas sensitive test results are shown in fig. 8. As can be seen from FIG. 8, the cotton-based carbon quantum dot gas-sensitive sensing material is aligned to 100ppm of NH₃The average response value of the kit reaches 365%, and the kit shows higher detection sensitivity.

The gas-sensitive sensing performance of the carbon quantum dots prepared in example 1 was tested by the following specific steps: and (3) taking the carbon quantum dot dispersion liquid, dropwise adding the carbon quantum dot dispersion liquid onto the silver interdigital electrode sheet, and standing and drying the silver interdigital electrode sheet at room temperature for 24 hours. After drying, applying 4V voltage to two ends of electrode plate, electrifying and ageing for 12 hr, and testing 100ppm H₂O₂The gas sensitive test was performed, and the gas sensitive test results are shown in fig. 9. As can be seen from FIG. 9, the cotton-based carbon quantum dot gas-sensitive sensing material is aligned to 100ppm of H₂O₂The average response value of (2) reaches 3760%, and the high detection sensitivity is shown.

The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be construed as the protection scope of the present invention.