阅读说明：本技术 一种3d氮掺杂石墨烯/自组装多糖复合材料的制备及应用 (Preparation and application of 3D nitrogen-doped graphene/self-assembled polysaccharide composite material ) 是由 莫尊理 王嘉 牛小慧 赵盼 高琴琴 刘晶晶 姜洋洋 郭瑞斌 刘妮娟 于 2019-10-10 设计创作，主要内容包括：本发明公开了一种3D氮掺杂石墨烯/自组装多糖复合材料的制备及应用,混合均相石墨烯悬浮液与吡咯单体,煅烧,冷冻干燥,煅烧,得3D N-rGO；NaOH和β-环糊精配成混合溶液；加入CuSO<Sub>4</Sub>·5H<Sub>2</Sub>O溶液,室温剧烈搅拌,滤液中加入乙醇,离心,得Cu-β-CD,水中混合Cu-β-CD与CMC,超声,过滤,真空干燥,得CD-Cu-CMC；混合CD-Cu-CMC与去离子水,加入3D N-rGO,超声,离心洗涤,得3D氮掺杂石墨烯/自组装多糖复合材料。该复合材料用于超级电容器、电化学传感器、锂离子电池、纳米材料等领域。本发明制备方法制得的复合材料具有更好的电子传输性能。(The invention discloses preparation and application of a 3D nitrogen-doped graphene/self-assembled polysaccharide composite material, wherein homogeneous phase graphene suspension and pyrrole monomer are mixed, calcined, freeze-dried and calcined to obtain 3D N-rGO; preparing a mixed solution from NaOH and beta-cyclodextrin; adding CuSO 4 ·5H 2 Stirring O solution at room temperature, adding ethanol into the filtrate, centrifuging to obtain Cu-beta-CD, mixing Cu-beta-CD with CMC in water, performing ultrasonic treatment, filtering, and vacuum drying to obtain CD-Cu-CMC; mixing the CD-Cu-CMC with deionized water, adding 3D N-rGO, performing ultrasonic treatment, and performing centrifugal washing to obtain the 3D nitrogen-doped graphene/self-assembled polysaccharide composite material. The composite material is used for super capacitors, electrochemical sensors,Lithium ion battery, nanometer material and other fields. The composite material prepared by the preparation method has better electron transmission performance.)

1. A preparation method of a 3D nitrogen-doped graphene/self-assembled polysaccharide composite material is characterized by comprising the following steps:

1) dispersing 20-25 mg of graphene oxide in 40-45 mL of water to obtain a homogeneous graphene suspension, mixing the homogeneous graphene suspension with 2-3 mg of pyrrole monomer, performing ultrasonic dispersion, placing the mixture in an environment with the temperature of 180-185 ℃ for heat preservation for 12-13 hours, naturally cooling the mixture to room temperature to obtain gel, performing freeze drying, placing the gel in an environment with the temperature of 800-805 ℃ and introducing Ar atmosphere for calcining for 3.5-4.0 hours to obtain 3D nitrogen-doped graphene;

2) respectively taking NaOH and beta-cyclodextrin according to a molar ratio of 25: 1-1.2, uniformly mixing and stirring to prepare a mixed solution;

60-61 mL of CuSO with the concentration of 0.04M₄·5H₂Mixing the O solution with 40-41 mL of mixed solution, violently stirring for 10-12 hours at room temperature, filtering, adding 400-405 mL of ethanol into filtrate, standing for 10-12 hours, centrifuging to obtain Cu-beta-CD, washing with ethanol and distilled water, and drying; mixing 60-62 mL of sodium carboxymethylcellulose solution with mass volume concentration of 4mg/mL and Cu-beta-CD in water, carrying out ultrasonic treatment for 30-35 minutes, violently stirring for 10-12 hours, filtering, and carrying out vacuum drying to obtain Cu²⁺Self-assembly of a complex beta-cyclodextrin sodium carboxymethylcellulose composite material;

3) mixing Cu²⁺Self-assembled carboxymethyl of coordinated beta-cyclodextrinMixing the powder of the sodium cellulose composite material with deionized water to obtain a saturated and uniform solution; adding the 3D nitrogen-doped graphene prepared in the step 1), carrying out ultrasonic treatment for 1-1.5 hours, and carrying out centrifugal washing to obtain the 3D nitrogen-doped graphene/self-assembled polysaccharide composite material.

2. The method for preparing the 3D nitrogen-doped graphene/self-assembled polysaccharide composite material according to claim 1, wherein the preparation of the graphene oxide in the step 1): placing expandable graphite into a crucible, placing the crucible into a muffle furnace, and heating the crucible for 30-50 s at the temperature of 900-901 ℃ to prepare the expandable graphite; putting 1-1.1 g of expanded graphite into 500-501 mL of Dimethylformamide (DMF), performing ultrasonic treatment for 24-25 h, repeatedly washing and filtering with ethanol and water, and performing vacuum drying at 60-65 ℃ to obtain stripped graphene; placing 1-1.1 g of stripped graphite powder in a mixed acid solution consisting of 90mL of concentrated sulfuric acid and 30mL of concentrated phosphoric acid, cooling to about 0-1 ℃, then slowly adding 10-11 g of potassium permanganate, and controlling the reaction temperature to be below 5 ℃ to prevent explosion; after the potassium permanganate is completely dissolved, heating to 50-55 ℃, and stirring for 10-12 h; after the reaction is finished, cooling to room temperature, respectively adding 200mL of ice water and 5mL of hydrogen peroxide solution with the mass fraction of 30% until the liquid becomes golden yellow after the reaction, then dripping a few drops of hydrochloric acid to react excessive hydrogen peroxide, centrifuging, repeatedly washing, and freeze-drying to obtain the graphene oxide.

3. The method of preparing the 3D nitrogen-doped graphene/self-assembled polysaccharide composite material of claim 1, wherein: in the step 2), the mixed solution prepared by NaOH and beta-cyclodextrin contains 0.5M of NaOH and 0.02M of beta-cyclodextrin.

4. The method of preparing the 3D nitrogen-doped graphene/self-assembled polysaccharide composite material of claim 1, wherein: and in the step 3), washing the Cu-beta-CD for 3-4 times by using ethanol and distilled water.

5. Use of the 3D nitrogen-doped graphene/self-assembled polysaccharide composite material of claim 1.

6. The use of the 3D nitrogen-doped graphene/self-assembled polysaccharide composite material according to claim 4, wherein the 3D nitrogen-doped graphene/self-assembled polysaccharide composite material is used in an electrochemical sensor.

Technical Field

The invention belongs to the technical field of composite materials, and relates to preparation of a 3D nitrogen-doped graphene/self-assembled polysaccharide composite material and application of the composite material in an electrochemical sensor.

Background

Graphene is a two-dimensional carbon nanomaterial, and has been widely used in the fields of supercapacitors, electrochemical sensors, lithium ion batteries, nanomaterials, hydrogen storage, and the like. However, due to pi-pi action between layers, an inevitable agglomeration effect is caused, which makes the number of layers of graphene thicker and affects the conductivity of the graphene. Thus, the application of two-dimensional graphene is limited to some extent. Three-dimensional graphene is superior to two-dimensional graphene to a certain extent due to its relatively large specific surface area, more exposed active sites and fast electron transport performance. According to previous reports, the bandwidth of graphene can be changed by N-doped graphene, and defects can be induced in the graphene.

Beta-cyclodextrin is a polysaccharide composed of seven glucose units. The inner cavity of the cyclodextrin is hydrophobic, the outer cavity of the cyclodextrin is hydrophilic, and different types of guest molecules, such as amino acid molecules, anionic and cationic guests, polymer chains and the like, can be included in the inner cavity of the cyclodextrin, so that the cyclodextrin has wide application in electrochemical sensors. Beta-cyclodextrin is usually only simply complexed on one surface of the material. Therefore, the Cu-beta-CD self-assembled CMC and the N-doped graphene are compounded together, and the composite material is expected to be widely applied to electrochemical sensors.

Disclosure of Invention

The invention aims to provide a preparation method of a 3D nitrogen-doped graphene/self-assembled polysaccharide composite material.

It is another object of the present invention to provide the use of the above composite material.

The technical scheme adopted by the invention is as follows: a preparation method of a 3D nitrogen-doped graphene/self-assembled polysaccharide composite material specifically comprises the following steps:

1) preparation of Graphene Oxide (GO): placing expandable graphite into a crucible, placing the crucible into a muffle furnace, and heating the crucible for 30-50 s at the temperature of 900-901 ℃ to prepare the expandable graphite; putting 1-1.1 g of expanded graphite into 500-501 mL of Dimethylformamide (DMF), performing ultrasonic treatment for 24-25 h, repeatedly washing and filtering with ethanol and water, and performing vacuum drying at the temperature of 60-65 ℃ to obtain stripped graphene; placing 1-1.1 g of stripped graphite powder in a mixed acid solution consisting of 90mL of concentrated sulfuric acid and 30mL of concentrated phosphoric acid, cooling to about 0-1 ℃, then slowly adding 10-11 g of potassium permanganate, and controlling the reaction temperature to be below 5 ℃ to prevent explosion; after the potassium permanganate is completely dissolved, heating to 50-55 ℃, and stirring for 10-12 h; after the reaction is finished, cooling to room temperature, respectively adding 200mL of ice water and 5mL of hydrogen peroxide solution with the mass fraction of 30% until the reacted solution becomes golden yellow, then dripping a few drops of hydrochloric acid to react excessive hydrogen peroxide, centrifuging, repeatedly washing, and freeze-drying to obtain Graphene Oxide (GO);

2) preparation of 3D nitrogen-doped graphene (3D N-rGO): dispersing 20-25 mg of Graphene Oxide (GO) in 40-45 mL of water for 1.5-2.0 hours to obtain a homogeneous GO suspension, then mixing the homogeneous GO suspension with 2-3 mg of pyrrole monomer, performing ultrasonic dispersion, then placing a black dispersion in a sealed Teflon-lined autoclave, keeping the autoclave at the temperature of 180-185 ℃ for 12-13 hours, and naturally cooling the autoclave to room temperature to obtain gel; after the gel is frozen and dried, calcining the gel for 3.5 to 4.0 hours in an environment with the temperature of 800 to 805 ℃ and Ar atmosphere to obtain 3D N-rGO;

3）Cu²⁺preparing a complex beta-cyclodextrin self-assembly sodium carboxymethyl cellulose composite material (CD-Cu-CMC):

respectively taking NaOH and beta-cyclodextrin (beta-CD) according to a molar ratio of 25: 1-1.2, uniformly mixing and stirring to prepare a mixed solution, wherein the mixed solution contains 0.5M of NaOH and 0.02M of beta-cyclodextrin;

60-61 mL of CuSO with the concentration of 0.04M₄·5H₂Mixing the O solution with 40-41 mL of mixed solution, vigorously stirring at room temperature for 10-12 hours, and filtering to remove Cu (OH)₂Precipitating; adding 400-405 mL of ethanol into the filtrate, standing for 10-12 hours, and centrifuging to obtain Cu-beta-CD; washing the synthesized Cu-beta-CD with ethanol and distilled water for several times, and drying in a ventilating way; 60-62 mL of sodium carboxymethylcellulose (CMC) solution (solvent is H) with the mass volume concentration of 4mg/mL₂O) and Cu-beta-CD are mixed in water and are subjected to ultrasonic treatment for 30-35 minutes, are vigorously stirred for 10-12 hours, are filtered, and are dried for 48-50 hours in a vacuum drier at the temperature of 25-30 ℃ to obtain Cu²⁺A coordinated beta-cyclodextrin self-assembled sodium carboxymethylcellulose composite material (CD-Cu-CMC);

4) preparation of 3D nitrogen-doped graphene/self-assembled polysaccharide composite (3D N-rGO/CD-Cu-CMC): mixing the powder of the CD-Cu-CMC with deionized water to obtain a saturated and uniform solution; and then adding the 3D N-rGO prepared in the step 1) into the solution, carrying out ultrasonic treatment for 1-1.5 hours, and carrying out centrifugal washing for 3-4 times to remove free CD-Cu-CMC remained on the 3D N-rGO so as to obtain the 3D nitrogen-doped graphene/self-assembled polysaccharide composite material (3D N-rGO/CD-Cu-CMC).

The other technical scheme adopted by the invention is as follows: an application method of the 3D nitrogen-doped graphene/self-assembled polysaccharide composite material prepared by the preparation method in an electrochemical sensor specifically comprises the following steps: the 3D nitrogen-doped graphene/self-assembly polysaccharide composite material is uniformly dispersed in water to form a dispersion liquid with the mass volume concentration of 1mg/mL, and then 8 mu L of the dispersion liquid is dripped on the surface of a treated glassy carbon electrode to construct 3D N-rGO/CD-Cu-CMC/GCE.

Characterization of 3D nitrogen-doped graphene/self-assembled polysaccharide composite material

1. Infrared spectrogram

FIG. 1 is a graph of CD-Cu-CMC, Cu-beta-CD, CMC, and beta-CD infraredSpectrogram of 3409.1cm for beta-CD^-1Shows a stretching vibration peak of-OH at 2931.3cm^-1Is represented by-CH₂At 1023cm^-1A peak of C-O is shown; CMC of 3433cm^-1Shows a stretching vibration peak of-OH at 2920cm^-1Is represented by-CH₂Peak of (4) at 1620cm^-1Has a peak of C = O at 1060cm^-1A peak of C-O-C; Cu-beta-CD is 878cm^-1And 577cm^-1A typical tensile vibration peak is shown in figure 1 a. The amplified wave number range is 950cm^-1To 400cm^-1Region, appearing at 878cm^-1The peak at (A) is due to HOH and Cu^{2 +}And is in the range of 577cm^-1The other less pronounced peak at (a) is due to Cu — O, see fig. 1 b. The CD-Cu-CMC composite material has characteristic peaks of CMC and Cu-beta-CD. Furthermore, it appears at 878cm^-1And 577cm^-1The peak intensity at (a) increased, further indicating the successful synthesis of CD-Cu-CMC.

2. Scanning electron microscope image

FIG. 2 is a scanning electron micrograph of 3D N-rGO and CD-Cu-CMC. As can be seen from the electron micrograph of 3D N-rGO (FIG. 2 a), it has a typical three-dimensional structure and a hollow structure, which is favorable for the electron transport. The CD-Cu-CMC electron micrograph (fig. 2 b) shows that the open honeycomb structure has a large surface area, which is advantageous for the loading of guest molecules and the transport of electrons.

Secondly, testing the electrochemical performance of the 3D nitrogen-doped graphene/self-assembled polysaccharide composite material prepared by the preparation method

1. Preparation of modified electrode

And uniformly dispersing the prepared 3D N-rGO/CD-Cu-CMC into water to form a dispersion liquid with the mass volume concentration of 1-1.2 mg/mL, and then dropwise coating the dispersion liquid on the surface of a treated glassy carbon electrode to construct an electrode 3D N-rGO/CD-Cu-CMC/GCE.

Uniformly dispersing the 3D N-rGO prepared in the step 1) into water to form a dispersion liquid with the mass volume concentration of 1mg/mL, and then dropwise coating the dispersion liquid on the surface of a treated glassy carbon electrode to construct an electrode 3D N-rGO/GCE.

Uniformly dispersing the CD-Cu-CMC prepared in the step 2) into water to form a dispersion liquid with the mass volume concentration of 1mg/mL, and then dropwise coating the dispersion liquid on the surface of the treated glassy carbon electrode to construct an electrode CD-Cu-CMC/GCE.

2. Modifying the electrochemical performance of an electrode

A Glassy Carbon Electrode (GCE) and the electrodes 3D N-rGO/GCE, CD-Cu-CMC/GCE and 3D N-rGO/CD-Cu-CMC/GCE prepared as described above were immersed in Fe (CN) at a concentration of 5 mM, respectively₆ ^4−/3−Containing 0.1M KCl solution as supporting electrolyte, with a scanning potential of-0.2V to 0.6V and a scanning speed of 0.05V/s. The electrochemical performance of each electrode was measured by cyclic voltammetry. The CV curve of the modified electrode is shown in fig. 3. As can be seen from FIG. 3, the magnitude of the peak current is 3D N-rGO/GCE > 3D N-rGO/CD-Cu-CMC/GCE > CD-Cu-CMC/GCE in this order. In addition, it was observed that when the CD-Cu-CMC/GCE was immersed in 5 mM Fe (CN)₆ ^4−/3−The reduction in peak current is evident when compared to a bare electrode when containing a 0.1M KCl solution, due to Fe (CN)₆ ^4−/3−The cavity of (a) and the cavity of the cyclodextrin do not match in size, the cyclodextrin cavity is hydrophobic, and Fe (CN)₆ ^4−/3−Has hydrophilic properties and is also larger in size than cyclodextrin. Thus, Fe (CN)₆ ^4−/3−Can not enter the cyclodextrin cavity to generate oxidation-reduction reaction.

According to the preparation method, Graphene Oxide (GO) and pyrrole are used as precursors to prepare the 3D nitrogen-doped graphene (3D N-rGO). Due to the conjugated structure of pyrrole, pyrrole can attach to GO through hydrogen bonding and pi-pi interactions, providing a source of N. During thermal annealing, N-doping occurs more easily at the defects and edges of the GO layer and reduces GO to rGO. Cu^{2 +}And beta-cyclodextrin (Cu-beta-CD) coordination and sodium carboxymethylcellulose (CMC) are self-assembled into sodium carboxymethylcellulose (CD-Cu-CMC) which is used as a chiral selector, and then the sodium carboxymethylcellulose (CD-Cu-CMC) is compounded with 3D N-rGO to prepare the composite material 3D N-rGO/CD-Cu-CMC. Electrochemical performance detection shows that the 3D N-rGO/CD-Cu-CMC composite material prepared by the invention has better electron transmission performance and can be applied to the fields of super capacitors, electrochemical sensors, lithium ion batteries, nano materials and the like. Scanning Electron Microscope (SEM),Infrared spectroscopy (FT-IR) and electrochemical methods were used to characterize the synthesis of the composite.

Drawings

Fig. 1 is an infrared spectrum of the 3D nitrogen-doped graphene/self-assembled polysaccharide composite material prepared by the preparation method of the present invention.

FIG. 2 is a scanning electron micrograph of 3D N-rGO and CD-Cu-CMC.

FIG. 3 shows Fe (CN)₆ ^4−/3−Cyclic voltammograms at different modified electrodes.

Detailed Description

The preparation of the composite material according to the invention is further illustrated by the following specific examples.