A method for preparing a graphene / carbon nanotube composite slurry and its application.
By carboxylating the surface of multi-walled carbon nanotubes and dispersing them with nitrogen bubbles, combined with melamine electropolymerization, the graphene agglomeration problem was solved, increasing the specific surface area and conductivity of the composite slurry, and improving the performance of the electrochemical sensor and the sensitivity of clonazepam detection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ANHUI UNIV OF SCI & TECH
- Filing Date
- 2024-03-14
- Publication Date
- 2026-05-26
AI Technical Summary
In existing graphene/modified carbon nanotube composite slurries, graphene agglomeration leads to a decrease in specific surface area and conductivity, which affects the performance of electrochemical sensors.
By carboxylation treatment of multi-walled carbon nanotubes, acylation modification, nitrogen bubble-assisted dispersion, and melamine electropolymerization, the dispersibility and uniformity of graphene and carbon nanotubes are improved, the specific surface area is increased, and a highly conductive composite slurry is formed.
The electrochemical and catalytic properties of the composite slurry were improved, the signal response and selectivity of the electrochemical sensor were enhanced, and the sensitivity and anti-interference ability to clonazepam were improved.
Smart Images
Figure CN118387863B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electrochemical sensing, and more particularly to a method for preparing a graphene / carbon nanotube composite slurry and its application. Background Technology
[0002] Graphene / modified carbon nanotube composite slurry is a slurry made by mixing graphene and modified carbon nanotubes. Graphene is a two-dimensional material composed of a single layer of carbon atoms, possessing excellent electrical conductivity, thermal conductivity, and mechanical properties, and can be used to enhance the performance of materials. Carbon nanotubes are hollow nanotube structures formed by carbon atoms, possessing excellent properties such as high strength, high electrical conductivity, and high thermal conductivity.
[0003] Graphene is a two-dimensional material composed of a single layer of carbon atoms, possessing excellent electrical, thermal, and mechanical properties. Modified carbon nanotubes are carbon nanotubes that have been modified by introducing chemical functional groups or coating them with other materials. This composite slurry combines the advantages of both materials and has broad application potential in many fields.
[0004] Graphene / modified carbon nanotube composite slurry possesses several superior properties. First, due to the high conductivity of graphene and carbon nanotubes, this composite slurry has significant application value in the fabrication of electronic devices. Second, the high strength and high conductivity of the graphene / modified carbon nanotube composite slurry make it an ideal material for fabricating high-performance sensors. Furthermore, this composite slurry can also be used to fabricate high-performance energy storage devices, such as supercapacitors and lithium-ion batteries. Finally, due to the low-dimensional properties of graphene and carbon nanotubes, the graphene / modified carbon nanotube composite slurry exhibits good flexibility and bendability, making it suitable for the fabrication of flexible electronic devices. In conclusion, the graphene / modified carbon nanotube composite slurry is a composite material slurry with excellent performance and broad application potential, and it is expected to play an important role in the fields of electronics, sensors, and energy storage devices.
[0005] Clonazepam, also known as 1,3-dihydro-7-nitro-5-(2-chlorophenyl)-2H-1,4-benzodiazepine-2-one, is an effective sedative primarily used to treat epilepsy, panic disorder, chronic fatigue syndrome, and akathisia. It is suitable for both adults and children. As a benzodiazepine sedative, clonazepam is orally administered, thus eliminating the need for intravenous infusion in cases of status epilepticus. It affects imbalanced chemicals in the brain by increasing the frequency of activation of gamma-aminobutyric acid (GABA) receptors. Clonazepam is commonly consumed worldwide as a recreational substitute. It is important to note that frequent use can develop tolerance and dependence, and withdrawal symptoms can occur if clonazepam is reduced or discontinued.
[0006] Chinese Patent Publication No. CN113428851B discloses a graphene-carbon nanotube composite slurry and its preparation method. The method involves adding fully oxidized graphene oxide to a dilute acid solution and stirring until homogeneous to obtain component A. Carbon nanotube powder is then added to component A, stirred until homogeneous, and filtered to obtain a graphene oxide / carbon nanotube filter material. The filter material is then acid-washed at least three times with a dilute acid solution. Finally, the filter material is extruded, granulated, dried, and thermally reduced to obtain the graphene-carbon nanotube composite slurry. By combining the acid washing and purification processes of graphene oxide and carbon nanotubes, a one-step acid purification process is achieved, reducing the acid purification process and waste liquid generation, lowering acid washing costs, reducing pollution, and resulting in a composite slurry with excellent electrical conductivity.
[0007] However, due to the agglomeration of graphene, the specific surface area of the composite material decreases, ultimately leading to a decline in conductivity. To obtain a rapid and sensitive quantitative procedure for clonazepam in biological samples such as plasma and serum to aid in the diagnosis of potential poisoning victims or to assist in the forensic detection of fatal drug poisoning cases, and to conduct efficient, selective, and highly sensitive diagnostics in pharmacological studies, the electrical activity of the composite material is crucial. Summary of the Invention
[0008] This application provides a method for preparing a graphene / carbon nanotube composite slurry and its application, which solves the graphene agglomeration problem in the prior art and achieves the technical effects of increasing the specific surface area and improving the electrical activity of the composite slurry.
[0009] This application provides a method for preparing a graphene / carbon nanotube composite slurry, the specific steps of which include:
[0010] S1. Place 5g of multi-walled carbon nanotubes into 100mL of concentrated sulfuric acid, react at 60℃ for 5 hours, wash with deionized water until neutral, and dry at 100℃ for 12 hours to obtain carboxylated carbon nanotubes.
[0011] S2. Add 2g of carboxylated carbon nanotubes to 100mL of thionyl chloride, stir with a magnetic stirrer for 30 minutes, react at 45°C for 3 hours, wash the product with tetrahydrofuran, and dry at 100°C for 6 hours to obtain acyl chloride carbon nanotubes.
[0012] S3, based on its total weight, includes the following components in the following proportions: multi-walled carbon nanotubes 4.0-6.0%, graphene microsheets 0.2-1.0%, dispersant 0.5-1.0%, melamine 3.0-6.0%, balance NMP;
[0013] S4. Add the graphene oxide / carbon nanotube filter material to 80mL of a 3-5wt% dilute hydrochloric acid solution for acid washing and then purge with nitrogen bubbles. Stir well, filter, dry, and repeat 4 times.
[0014] The volume of nitrogen bubbles accounts for 40% of the solution volume; the nitrogen bubbles are generated by a micron-sized bubble generator.
[0015] Furthermore, the multi-walled nanotubes described in step S1 have a length of 10-30 μm, an outer diameter of 10-20 nm, and an inner diameter of 5-10 nm.
[0016] Further, the specific preparation method of step S3 is as follows: after mixing acyl chloride carbon nanotubes, graphene microsheets, dispersant and N-methylpyrrolidone according to the specific component composition, the mixture is pre-dispersed in a disperser at 8000 rpm for 60 min, and then dispersed evenly in a high-pressure homogenizer at 1200 bar to obtain a premix; the premix is then ground in a grinder for 45-60 minutes to obtain a graphene / carbon nanotube-based composite slurry.
[0017] Furthermore, the dispersant is polyvinyl alcohol.
[0018] Furthermore, the composite slurry also includes 0.5-2% binder.
[0019] Furthermore, the adhesive is polyvinylidene fluoride.
[0020] An application of a graphene / carbon nanotube composite slurry in electrochemical response.
[0021] Furthermore, the fabrication method for sensors applied to electrochemical responses is as follows:
[0022] The glassy carbon electrode coated with the composite slurry was placed in a vacuum drying oven and dried at 80°C for 2 hours to obtain an electrochemical sensor based on graphene / modified carbon nanotube composite slurry / GCE.
[0023] Furthermore, the electrochemical sensor also contains melamine.
[0024] Furthermore, the preparation method of the electrochemical sensor containing melamine is as follows:
[0025] A glassy carbon electrode coated with graphene / modified carbon nanotube composite slurry was placed in a 0.04M BR buffer solution containing 1mM melamine at pH 7.0. A cyclic potential scan was performed from 0.1V to 1.8V for 30 cycles at a scan rate of 100 mV / s to conduct melamine electropolymerization, resulting in an electrochemical sensor based on melamine and graphene / modified carbon nanotube composite slurry / GCE.
[0026] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:
[0027] Firstly, multi-walled carbon nanotubes are treated with concentrated sulfuric acid to add carboxyl (-COOH) functional groups to their surface, which increases the water solubility and reactivity of the carbon nanotubes. The carboxylated carbon nanotubes further react with thionyl chloride to transform into acyl chloride carbon nanotubes, thereby improving the reactivity of the carbon nanotubes.
[0028] Secondly, acyl chloride carbon nanotubes, graphene microsheets, dispersant and melamine are mixed and dispersed in N-methylpyrrolidone (NMP) to improve the uniformity of the mixture. The carbon nanotubes and graphene microsheets are uniformly dispersed in NMP, which reduces the possibility of agglomeration and breaks up the already agglomerated groups.
[0029] Thirdly, the introduction of nitrogen bubbles allows graphene and carbon nanotubes in the composite slurry to expand more fully, thereby increasing their specific surface area and providing more active sites and reaction interfaces, which is beneficial to improving the electrochemical and catalytic performance of the composite slurry. Stirring in nitrogen bubbles increases the dispersion of graphene and carbon nanotubes in the solution, improving their uniform distribution. The initially high nitrogen bubble volume ratio forms a large number of microbubbles in the solution, which can disperse graphene oxide and carbon nanotubes and prevent agglomeration. Subsequently, the nitrogen bubble volume ratio is gradually reduced, allowing the material to gradually adapt to and stabilize its dispersion state during the acid washing process, reducing material damage or over-stirring caused by excessive bubbles.
[0030] Fourth, graphene and carbon nanotubes are both excellent conductive materials. Their combination can significantly improve the conductivity of the electrode, thereby enhancing the signal response of the electrochemical sensor and increasing the effective surface area of the electrode, providing more active sites, which is beneficial to the electrochemical reaction. Vacuum drying can remove solvents and impurities from the slurry, improving the stability and reproducibility of the electrode. By electropolymerizing melamine on the electrode surface through cyclic potential scanning, a thin film with specific electrochemical properties can be formed, further improving the sensor's performance. The introduction of melamine makes the sensor more selective for clonazepam, thereby improving the sensor's sensitivity and anti-interference ability in practical applications. Attached Figure Description
[0031] Figure 1 EIS plots of GCE, graphene / carbon nanotube / GCE, and melamine / graphene / carbon nanotube / GCE in 0.1M hydrochloric acid solution.
[0032] Figure 2 Cyclic voltammetry of GCE, graphene / carbon nanotube / GCE, and melamine / graphene / carbon nanotube / GCE in 5 μM clonazepam was performed. Detailed Implementation
[0033] To facilitate understanding of the present invention, a more complete description of this application will be given below with reference to the accompanying drawings, which illustrate preferred embodiments of the invention. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to enable a more thorough and complete understanding of the disclosure of the present invention.
[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0035] Example 1
[0036] This application discloses a method for preparing a graphene / carbon nanotube composite slurry, the specific steps of which are as follows:
[0037] S1. Place 5g of multi-walled carbon nanotubes (length 10-30μm, outer diameter 10-20nm; inner diameter 5-10nm) into 100mL of concentrated sulfuric acid, react at 60℃ for 5 hours, wash with deionized water until neutral, and dry at 100℃ for 12 hours to obtain carboxylated carbon nanotubes.
[0038] S2. Add 2g of carboxylated carbon nanotubes to 100mL of thionyl chloride, stir with a magnetic stirrer for 30 minutes, react at 45°C for 3 hours, wash the product with tetrahydrofuran, and dry at 100°C for 6 hours to obtain acyl chloride carbon nanotubes.
[0039] S3. Based on its total weight, it includes the following components in the following proportions: multi-walled carbon nanotubes 4.0-6.0%, graphene microsheets 0.2-1.0%, dispersant 0.5-1.0%, melamine 3.0-6.0%, binder 0.5-2%, and the balance being NMP;
[0040] The specific preparation steps are as follows: Acyl chloride carbon nanotubes, graphene microsheets, binder polyvinylidene fluoride, dispersant PVA and N-methylpyrrolidone are mixed according to the specific component composition and pre-dispersed in a disperser at 8000 rpm for 60 min. Then, they are dispersed evenly in a high-pressure homogenizer at 1200 bar to obtain a premix. The premix is then ground in a grinder for 45-60 minutes to obtain a composite slurry based on graphene / carbon nanotubes.
[0041] S4. Add the graphene oxide / carbon nanotube filter material to 80mL of a 3-5wt% dilute hydrochloric acid solution for acid washing and then purge with nitrogen bubbles. Stir well, filter, dry, and repeat 4 times.
[0042] The volume of nitrogen bubbles accounts for 40% of the solution volume; the nitrogen bubbles are generated by a micron-sized bubble generator.
[0043] Each pickling process reduces the nitrogen bubble volume ratio compared to the previous pickling. Specifically, the nitrogen bubble volume ratio is 35% for the first pickling, 30% for the second, 25% for the third, and 20% for the fourth.
[0044] The technical solutions described in the embodiments of this application have at least the following technical effects or advantages:
[0045] Multi-walled carbon nanotubes are treated with concentrated sulfuric acid to add carboxyl (-COOH) functional groups to their surface, which increases the water solubility and reactivity of the carbon nanotubes. The carboxylated carbon nanotubes further react with thionyl chloride to transform into acyl chloride carbon nanotubes, thereby improving the reactivity of the carbon nanotubes.
[0046] Acyl chloride carbon nanotubes, graphene microsheets, dispersant and melamine are mixed and dispersed in N-methylpyrrolidone (NMP) to improve the uniformity of the mixture. The carbon nanotubes and graphene microsheets are uniformly dispersed in NMP, which reduces the possibility of agglomeration and breaks up the already agglomerated groups.
[0047] The introduction of nitrogen bubbles allows graphene and carbon nanotubes in the composite slurry to expand more fully, thereby increasing their specific surface area and providing more active sites and reaction interfaces, which is beneficial to improving the electrochemical and catalytic performance of the composite slurry. Stirring in nitrogen bubbles increases the dispersion of graphene and carbon nanotubes in the solution, improving their uniform distribution. The initially high nitrogen bubble volume ratio forms a large number of microbubbles in the solution, which can disperse graphene oxide and carbon nanotubes and prevent agglomeration. Subsequently, the nitrogen bubble volume ratio is gradually reduced, allowing the material to gradually adapt to and stabilize its dispersion state during the acid washing process, reducing material damage or over-stirring caused by excessive bubbles.
[0048] Example 2
[0049] Fabrication of graphene / carbon nanotube composite slurry electrochemical sensor:
[0050] The glassy carbon electrode coated with the composite slurry was placed in a vacuum drying oven and dried at 80°C for 2 hours to obtain an electrochemical sensor based on graphene / modified carbon nanotube composite slurry / GCE.
[0051] Fabrication of a composite slurry electrochemical sensor using melamine and graphene / carbon nanotubes:
[0052] A glassy carbon electrode coated with graphene / modified carbon nanotube composite slurry was placed in a 0.04M BR buffer solution containing 1mM melamine at pH 7.0. A cyclic potential scan was performed from 0.1V to 1.8V for 30 cycles at a scan rate of 100 mV / s to conduct melamine electropolymerization, resulting in an electrochemical sensor based on melamine and graphene / modified carbon nanotube composite slurry / GCE.
[0053] The technical solutions described in the embodiments of this application have at least the following technical effects or advantages:
[0054] Graphene and carbon nanotubes are both excellent conductive materials. Their combination can significantly improve the conductivity of the electrode, thereby enhancing the signal response of the electrochemical sensor, increasing the effective surface area of the electrode, providing more active sites, and facilitating the electrochemical reaction.
[0055] Vacuum drying can remove solvents and impurities from the slurry, improving the stability and reproducibility of the electrode.
[0056] By electropolymerizing melamine on the electrode surface through cyclic potential scanning, a thin film with specific electrochemical properties can be formed, further improving the sensor's performance. The introduction of melamine makes the sensor more selective for clonazepam, thereby improving the sensor's sensitivity and anti-interference ability in practical applications.
[0057] Example 3
[0058] The EIS spectra of GCE, graphene / carbon nanotube / GCE, and melamine / graphene / carbon nanotube / GCE were recorded under 0.1 M hydrochloric acid solution conditions. Electrochemical EIS measurements were performed. Figure 1 It shows:
[0059] The impedance spectrum of graphene / carbon nanotube / GCE shows a very large semi-circular cross section.
[0060] In particular, compared with melamine / graphene / carbon nanotube / GCE, the polymerization on the surface of melamine / graphene / carbon nanotube / GCE reduces the diameter of the impedance semicircle.
[0061] This is because melamine has relatively poor electrical conductivity; the semicircles of graphene / carbon nanotubes / GCE are relatively smaller than those of GCE, indicating that the conductivity of the modified GCE has been improved.
[0062] Cyclic voltammetry (CVs) of 5 μM clonazepam in 0.04 M BR buffer (pH 7.0) was recorded under bare GCE, graphene / carbon nanotube / GCE, and melamine / graphene / carbon nanotube / GCE conditions.
[0063] like Figure 2 As shown, a weak and broad peak was observed at 0.7 V on the melamine / graphene / carbon nanotube / GCE surface, which, compared with GCE, confirms the good electroreduction effect of the electrode modification process on clonazepam molecules.
[0064] The results show that:
[0065] Besides the π-π interaction between the aromatic ring of clonazepam and the acyl groups in the modified carbon nanotubes, the appropriate interaction between clonazepam and melamine significantly increases the physical adsorption of clonazepam on the melamine / graphene / carbon nanotube / GCE surface. Furthermore, the high conductivity of graphene / carbon nanotubes and the enhanced effective surface area of GCE after surface modification with nanomaterials make melamine / graphene / carbon nanotube / GCE a suitable sensor for the electrochemical analysis of clonazepam molecules. In summary, the improved response of clonazepam molecules on the modified electrode is due to factors such as the effective surface area, faster heterogeneous electron transfer, and higher active adsorption.
[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. An application of a graphene / carbon nanotube composite slurry in the detection of clonazepam, characterized in that, Methods for preparing composite slurries include: S1. Place 5g of multi-walled carbon nanotubes into 100mL of concentrated sulfuric acid, react at 60℃ for 5 hours, wash with deionized water until neutral, and dry at 100℃ for 12 hours to obtain carboxylated carbon nanotubes. S2. Add 2g of carboxylated carbon nanotubes to 100mL of thionyl chloride, stir with a magnetic stirrer for 30 minutes, react at 45°C for 3 hours, wash the product with tetrahydrofuran, and dry at 100°C for 6 hours to obtain acyl chloride carbon nanotubes. S3. Based on its total weight, it includes the following components in the following proportions: multi-walled carbon nanotubes 4.0-6.0%, graphene microsheets 0.2-1.0%, dispersant 0.5-1.0%, melamine 3.0-6.0%, and the balance being N-methylpyrrolidone; the specific preparation method is as follows: acyl chloride carbon nanotubes, graphene microsheets, dispersant, melamine, and N-methylpyrrolidone are mixed according to the specific component composition and pre-dispersed at 8000 rpm for 60 min, then dispersed evenly in a high-pressure homogenizer at 1200 bar to obtain a premix; the premix is then ground in a grinder for 45-60 minutes to obtain a graphene / carbon nanotube-based composite slurry; S4. Add the graphene oxide / carbon nanotube filter material to 80 mL of a 3-5 wt% dilute hydrochloric acid solution for acid washing and then introduce nitrogen bubbles. After stirring evenly, filter and dry, and repeat 4 times. The volume ratio of nitrogen bubbles in the first acid washing is 35%, the second acid washing is 30%, the third acid washing is 25%, and the fourth acid washing is 20%. Then filter and dry to obtain the graphene / carbon nanotube composite slurry. An electrochemical sensor containing melamine was prepared from a composite slurry for the detection of clonazepam. The specific preparation method of the electrochemical sensor is as follows: A glassy carbon electrode coated with a composite slurry was placed in a vacuum drying oven and dried at 80°C for 2 hours to obtain an electrochemical sensor based on graphene / modified carbon nanotube composite slurry / GCE. The glassy carbon electrode coated with the graphene / modified carbon nanotube composite slurry was then placed in a pH 7.0 buffer solution containing 1 mM melamine and 0.04 M BR. A cyclic potential scan was performed at a scan rate of 100 mV / s from 0.1 V to 1.8 V for 30 cycles to conduct melamine electropolymerization, resulting in an electrochemical sensor based on melamine and graphene / modified carbon nanotube composite slurry / GCE.
2. The application of the graphene / carbon nanotube composite slurry as described in claim 1 in the detection of clonazepam, characterized in that, The multi-walled nanotubes described in step S1 have a length of 10-30 μm, an outer diameter of 10-20 nm, and an inner diameter of 5-10 nm.
3. The application of the graphene / carbon nanotube composite slurry as described in claim 1 in the detection of clonazepam, characterized in that, The dispersant is polyvinyl alcohol.
4. The application of the graphene / carbon nanotube composite slurry as described in claim 1 in the detection of clonazepam, characterized in that, The composite slurry also includes 0.5-2% binder.
5. The application of the graphene / carbon nanotube composite slurry as described in claim 4 in the detection of clonazepam, characterized in that... The adhesive is polyvinylidene fluoride.