A graphene / carbon nanotube composite material and its preparation method

Abstract

The present invention discloses a preparation method of a graphene / carbon nanotube composite material, which includes preparing a modified KCNTs-COOH solution; preparing a modified KGO solution; mixing the modified KCNTs-COOH solution and the modified KGO solution and adding them into a mixed solution of absolute ethanol and deionized water, and stirring at a constant temperature; drying and grinding in an oven; dissolving the dried and ground powder in absolute ethanol, stirring at room temperature, washing with an absolute ethanol solution for multiple times, and then washing with deionized water for multiple times to obtain a sample; putting the sample into an electrothermal constant temperature blast drying oven for drying and grinding to obtain the graphene / carbon nanotube composite material. For the graphene / carbon nanotube composite material prepared by the present invention, the graphene oxide modified by KH550 on the surface has functional groups, and the modified KCNTs-COOH and the modified KGO are bonded to form a three-dimensional GO / CNTs-COOH composite material, which has good stability and good electrical conductivity and can be used as an electrode material for supercapacitors.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite materials, and particularly relates to a graphene / carbon nanotube composite material and a preparation method thereof. Background Art

[0002] Graphene and carbon nanotubes are excellent two-dimensional and one-dimensional carbon materials respectively, and have similar properties in terms of electricity and mechanics. However, due to different structures, they also have many differences. Graphene has become an ideal capacitive material due to its large specific surface area, high electronic conductivity and good mechanical properties. However, the theoretical capacity of graphene is not high, and stacking is likely to occur during the preparation of graphene-based electrodes, resulting in a decrease in the specific surface area and ionic conductivity of the material. The curvature radius of carbon nanotubes is small, and it is difficult to load nano-active substances onto them, which limits their application in electronic devices. In order to combine the advantages of both, combining the two materials to prepare composite electrode materials has become an effective solution.

[0003] A large number of studies have been carried out on electric double layer capacitors based on graphene / carbon nanotube composite materials. Cheng et al. (Cheng Qian, Tang Jie, Ma Jun, et al. Graphene and carbon nanotube composite electrodes for supercapacitors with ultra-high energy density. Phy Chem, 2011, 13: 17615-17624.) synthesized a graphene / single-walled carbon nanotube composite film by a simple stirring method, with an energy density of 62.8 Wh / kg and a power density of 58.5 kW / kg. Zhang et al. (Zhang Dengsong, Yan Tingting, Shi Liyi, et al. Enhanced capacitive deionization performance of graphene / carbon nanotube composites. Mater Chem, 2012, 22: 14696-14704.) successfully inserted carbon nanotubes between graphene sheets through π-π self-assembly between graphene oxide and carbon nanotubes, preventing the stacking of graphene sheets. This preparation process is simple, low-cost and environmentally friendly, but the composite material has a simple structure, single morphology and low designability, and the electrochemical performance of the composite material is affected.

[0004] Therefore, in the existing graphene / carbon nanotube composites, graphene and carbon nanotubes are not truly compounded, and their respective characteristics cannot be fully utilized, which limits the practical application of the materials. Summary of the Invention

[0005] To solve the above technical problems, in the present invention, graphene oxide (GO) is surface-modified with silane coupling agent γ-aminopropyltriethoxysilane (KH550) to prepare KGO. Secondly, carboxylated carbon nanotubes (CNTs-COOH) are surface-modified with silane coupling agent γ-aminopropyltriethoxysilane (KH560). Finally, a bridge is established through chemical bonding between the modified KGO and the modified KCNTs-COOH to form a GO / CNTs-COOH composite material with a stable three-dimensional structure and excellent electrical conductivity.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a preparation method of a graphene / carbon nanotube composite material, comprising the following steps:

[0007] Step 1: Weigh a certain mass of carboxylated carbon nanotubes (CNTs-COOH) and place them in a container. Slowly add a certain amount of the first silane coupling agent, and after ultrasonic dispersion treatment for 30 min, a dispersion is obtained.

[0008] Step 2: Heat the dispersion in an oil bath reflux device at 80°C for 24 h with continuous stirring to obtain a modified KCNTs-COOH solution.

[0009] Step 3: Weigh a certain mass of graphene oxide (GO) and add it to absolute ethanol, and perform ultrasonic dispersion treatment for 30 min.

[0010] Step 4: After the ultrasonic treatment, add the second silane coupling agent, and heat it in an oil bath at 80°C for 8 h with continuous stirring to obtain a modified KGO solution.

[0011] Step 5: Mix the modified KCNTs-COOH solution and the modified KGO solution and add them to a mixed solution of absolute ethanol and deionized water at a ratio of 1:1, and stir at a constant temperature for 12 hours. Dry in a drying oven at 40°C and crush.

[0012] Step 6: Dissolve the dried and crushed powder in absolute ethanol, stir at room temperature for 12 h, wash it with absolute ethanol solution for multiple times, and then wash it with deionized water for multiple times to obtain a sample.

[0013] Step 7: Dry the sample in an electrothermal constant temperature blast drying oven at 40°C and crush it to obtain a graphene / carbon nanotube (GO / CNTs-COOH) composite material.

[0014] Preferably, as the above technical solution, the first silane coupling agent is γ-glycidoxypropyltrimethoxysilane.

[0015] Preferably, as the above technical solution, the second silane coupling agent is γ-aminopropyltriethoxysilane.

[0016] Preferably, as the above technical solution, in the first step, the weight ratio of CNTs-COOH to the first silane coupling agent is 0.16 - 0.79:100.

[0017] Preferably, as the above technical solution, in the first step, the weight ratio of CNTs-COOH to the first silane coupling agent is 0.48:100

[0018] Preferably, as the above technical solution, in the third and fourth steps, the weight ratio of GO to the second silane coupling agent is 0.9 - 4.5:100.

[0019] Preferably, as the above technical solution, in the third and fourth steps, the weight ratio of GO to the second silane coupling agent is 2.65:100.

[0020] Preferably, as the above technical solution, the mass ratio of KGO to KCNTs-COOH is 1:0.2 - 5.

[0021] Preferably, as the above technical solution, the mass ratio of KGO to KCNTs-COOH is 5:1.

[0022] The graphene / carbon nanotube composite material is prepared by the above preparation method.

[0023] The beneficial effects of the present invention are as follows: The present invention uses a chemical bridging method to prepare a graphene / carbon nanotube composite material. The graphene oxide modified by KH550 has functional groups on its surface. The modified KCNTs-COOH and the modified KGO are bonded, and a chemical bridge is formed by using the chemical reaction between the amino group in KH550 and the epoxy group in KH560 to form a three-dimensional structure of graphene / carbon nanotube (GO / CNTs-COOH) composite material with good stability. Moreover, the prepared GO / CNTs-COOH composite material has good electrical conductivity and can be used as an electrode material for supercapacitors. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a process flow chart for preparing the graphene / carbon nanotube composite material of the present invention;

[0025] Figure 2 is an FTIR curve graph of GO and KGO;

[0026] Figure 3It is the FTIR curve diagram of CNTs-COOH and KCNTs-COOH;

[0027] Figure 4 It is the TGA curve diagram of GO, CNTs-COOH, D-2, and E-2;

[0028] Figure 5 It is the XRD curve diagram of graphite and GO;

[0029] Figure 6 It is the XRD curve diagram of GO, CNTs-COOH, B-1, C-1, and D-1;

[0030] Figure 7 It is the XRD curve diagram of KGO;

[0031] Figure 8 It is the XRD curve diagram of D-1, D-2, and D-3 composites;

[0032] Figure 9 It is the XRD curve diagram of E-1, E-2, and E-3 composites. Detailed implementation manners

[0033] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] Example 1

[0035] Step 1: Weigh 0.83 g of CNTs-COOH and place it in a beaker. Slowly add 100 ml of γ-glycidoxypropyltrimethoxysilane (KH560) as the first silane coupling agent, and perform ultrasonic dispersion treatment for 30 min to obtain a dispersion;

[0036] Step 2: Heat the dispersion in an oil bath reflux device at 80 °C for 24 h with continuous stirring at a rotation speed of 200 r / min to obtain a modified KCNTs-COOH solution;

[0037] Step 3: Weigh 0.17 g of GO and add it to 100 ml of absolute ethanol, and perform ultrasonic dispersion treatment for 30 min;

[0038] Step 4: After the ultrasonic treatment, add 20 ml of γ-aminopropyltriethoxysilane (KH550) as the second silane coupling agent, and heat it in an oil bath at 80 °C for 8 h with continuous stirring at a rotation speed of 200 r / min to obtain a modified KGO solution;

[0039] Step 5: Mix the modified KCNTs-COOH solution and the modified KGO solution in a mass ratio of 5:1 and add them to a mixed solution of absolute ethanol and deionized water. The mass ratio of absolute ethanol to deionized water is 1:1. Stir at a constant temperature for 12 hours. Dry in an oven at 40°C and then crush.

[0040] Step 6: Dissolve the dried and crushed powder in a large amount of absolute ethanol, stir at room temperature for 12 h, wash it 3 times with an absolute ethanol solution, and then wash it 3 times with deionized water to obtain a sample.

[0041] Step 7: Put the sample into an oven at 40°C for drying and crushing to obtain the graphene / carbon nanotube (GO / CNTs-COOH) composite material D-1.

[0042] Example 2

[0043] Step 1: Weigh 0.5 g of CNTs-COOH and place it in a beaker. Slowly add 100 ml of γ-glycidoxypropyltrimethoxysilane (KH560) as the first silane coupling agent. After ultrasonic dispersion treatment for 30 min, a dispersion is obtained.

[0044] Step 2: Heat the dispersion in an oil bath reflux device at 80°C for reflux for 24 h and continuously stir at a rotation speed of 200 r / min to obtain the modified KCNTs-COOH solution.

[0045] Step 3: Weigh 0.17 g of GO and add it to 100 ml of absolute ethanol, and perform ultrasonic dispersion treatment for 30 min.

[0046] Step 4: After the ultrasonic treatment, add 20 ml of γ-aminopropyltriethoxysilane (KH550) as the second silane coupling agent, heat it in an oil bath at 80°C for reflux for 8 h, and continuously stir at a rotation speed of 200 r / min to obtain the modified KGO solution.

[0047] Step 5: Mix the modified KCNTs-COOH solution and the modified KGO solution in a mass ratio of 1:1 and add them to a mixed solution of absolute ethanol and deionized water. The mass ratio of absolute ethanol to deionized water is 1:1. Stir at a constant temperature for 12 hours. Dry in an oven at 40°C and then crush.

[0048] Step 6: Dissolve the dried and crushed powder in a large amount of absolute ethanol, stir at room temperature for 12 h, wash it 3 times with an absolute ethanol solution, and then wash it 3 times with deionized water to obtain a sample.

[0049] Step 7: Put the sample into an oven at 40°C for drying and crushing to obtain the graphene / carbon nanotube composite material D-2.

[0050] Example 3

[0051] Step 1: Weigh 0.17 g of CNTs-COOH and place it in a beaker. Slowly add 100 ml of γ-glycidoxypropyltrimethoxysilane (KH560) as the first silane coupling agent. After ultrasonic dispersion treatment for 30 min, a dispersion is obtained.

[0052] Step 2: Heat the dispersion in an oil bath reflux device at 80 °C for 24 h with continuous stirring at a speed of 200 r / min to obtain a modified KCNTs-COOH solution.

[0053] Step 3: Weigh 0.83 g of GO and add it to 100 ml of absolute ethanol. Perform ultrasonic dispersion treatment for 30 min.

[0054] Step 4: After the ultrasonic treatment, add 20 ml of γ-aminopropyltriethoxysilane (KH550) as the second silane coupling agent. Heat it in an oil bath at 80 °C for 8 h with continuous stirring at a speed of 200 r / min to obtain a modified KGO solution.

[0055] Step 5: Mix the modified KCNTs-COOH solution and the modified KGO solution in a ratio of 1:5 by mass and add them to a mixed solution of absolute ethanol and deionized water with a mass ratio of absolute ethanol to deionized water of 1:1. Stir at a constant temperature for 12 h. Dry it in a drying oven at 40 °C and crush it.

[0056] Step 6: Dissolve the dried and crushed powder in a large amount of absolute ethanol. Stir at room temperature for 12 h, wash it 3 times with an absolute ethanol solution, and then wash it 3 times with deionized water to obtain a sample.

[0057] Step 7: Place the sample in an electrothermal constant temperature forced-air drying oven at 40 °C to dry it and crush it to obtain the graphene / carbon nanotube composite material D-3.

[0058] The dosages and ratios of the raw materials in the above examples are shown in the following table. At the same time, D-1, D-2, and D-3 are respectively treated in a muffle furnace at 600 °C for 5 min to obtain samples E-1, E-2, and E-3.

[0059] Name D-1 D-2 D-3 Dosage of GO (g) 0.17 0.50 0.83 Dosage of CNTs-COOH (g) 0.83 0.50 0.17 Ultrasonic time CO / CNTs-OOH (min) 30 / 30 30 / 30 30 / 30 Experimental compound mass ratio GO:CNTs-COOH 1:5 1:1 5:1 Sample treatment (muffle furnace at 600 °C, 5 min) E-1 E-2 E-3

[0060] The graphene / carbon nanotube composite materials prepared in Examples 1-3 above are respectively subjected to X-ray diffraction analysis (Rigaku D / max-3c, Japan), Fourier transform infrared spectroscopy test (Nicolet iN10 MX), thermogravimetric analysis (Shimadzu TA-60WS), and resistance test (Ningbo Ruike powder resistance meter FT-300I), etc.

[0061] The Fourier transform infrared spectroscopy (FTIR) test results of GO and modified GO (KGO) are as follows Figure 2 shown. It can be seen from the figure that the FTIR curves of GO in the figure have absorption peaks at 3413 cm -1 , 1734 cm -1 , 1626 cm -1 , 1396 cm -1 , 1229 cm -1 , 1092 cm -1 respectively. The absorption peak at 3413 cm -1 may be caused by the -OH stretching vibration of water molecules adsorbed on the surface of GO; the absorption peak at 1734 cm -1 corresponds to the -COOH stretching vibration peak at the edge of the GO layer; the relatively strong absorption peak at 1626 cm -1 corresponds to the -OH deformation vibration of water molecules; the absorption peak at 1396 cm -1 is the carboxyl C-O stretching vibration peak; the absorption peak at 1229 cm -1 is the epoxy group C-O symmetric absorption peak; the absorption peak at 1092 cm -1 is the stretching vibration peak of the ether bond C-O-C. The FTIR curves of KGO in the figure have absorption peaks at 3423 cm -1 , 2925 cm -1 , 1568 cm -1 , 1330 cm -1 , 1114 cm -1 respectively. The absorption peak at 3423 cm -1 corresponds to the -OH stretching vibration peak on the surface of GO; the characteristic peak at 2925 cm -1 is the saturated C-H stretching vibration absorption peak, the absorption peak at 1568 cm -1 is the C=C stretching vibration absorption peak, and the absorption peak at 1330 cm -1 is the epoxy group C-O symmetric absorption peak. However, it can also be found from the figure that the -COOH stretching vibration peak at 1734 cm -1 and the epoxy group C-O symmetric absorption peak at 1229 cm -1 in GO basically disappear, indicating that some amino groups in KH550 are likely to react with the epoxy groups. In addition, the stretching vibration absorption peak of the Si-O-C bond appears at 1114 cm -1 , which is mainly due to the fact that Si-OH generated by the hydrolysis of Si(OCH3) in KH550 reacts with -OH on the surface of GO in part. Therefore, KH550 has been successfully grafted onto the surface of GO.

[0062] The Fourier transform infrared spectroscopy (FTIR) test results of CNTs-COOH and modified CNTs-COOH are as follows Figure 3 shown. In the figure, CNTs-COOH has absorption peaks at 3467 cm -1 , 1107 cm -1 , and 681 cm -1 . Among them, a relatively broad absorption peak appears at 3467 cm -1 , which is caused by the stretching vibration of the -COOH group on the surface of CNTs-COOH. The absorption peak at 1107 cm -1 is generated by the stretching vibration of C-C on the sidewall of the carbon nanotube. However, in the curve of KCNTs-COOH modified by KH560, a relatively obvious absorption peak appears at 1633 cm -1 , which is the stretching vibration peak of C=O in the amide bond; the absorption peak at 1396 cm -1 can be considered to be caused by the stretching vibration of the Si-O group on the surface of the carbon nanotube. These results indicate that the surface of the treated carbon nanotube has generated a functional group of Si-O. Therefore, KH560 has been successfully grafted onto the surface of the carbon nanotube.

[0063] Thermogravimetric analysis (TGA) tests were carried out on GO, CNTs-COOH, D-2, and E-2, and the results are as follows Figure 4 shown. From the TGA curve of CNTs-COOH in Figure 4 , it can be found that CNTs-COOH only loses 23.26% of its weight from room temperature heating to 1000 °C. The lost mass is due to the weight loss of the -COOH grafted on the surface of CNTs-COOH, indicating that CNTs-COOH has fewer oxygen-containing groups and better thermal stability. Figure 4 From the TGA curve of D-2 in

[0064] . Through analysis, it can be divided into two stages: the weight loss before room temperature - 300 °C is mainly due to the degradation of a small amount of water and unreacted functional groups on the surface of the GO / CNTs-COOH composite material, and the weight loss rate is 11.29%. The weight loss after 300 - 800 °C may be caused by the decomposition of carbon-carbon bonds and carbon-silicon bonds in KH550 and KH560, and the weight loss rate is 55.17%. There is no thermal weight loss after 600 - 800 °C. And the thermal degradation behavior curve of D-2 is most similar to the thermal degradation curve of GO. The thermal weight loss curve of E-2 is relatively flat compared with that of D-2. The weight loss rate from room temperature to 600 °C is 10.31%, and the weight loss rate at 600 - 1000 °C is 13.95%, which is due to the reduction of oxygen-containing groups after E-2 is treated at high temperature. X-ray diffraction (XRD) was used to test and analyze graphene and GO, as shown in Figure 5As shown, they are the XRD curves of graphene and GO respectively. It can be seen from the figure that the position of the graphite diffraction peak is approximately at 2θ = 26.45°. According to the Bragg equation, the interlayer spacing of graphite is calculated to be approximately 0.336 nm. The diffraction peak of GO is at 2θ = 10.08°, and according to the Bragg equation, the interlayer spacing of GO is calculated to be approximately 0.876 nm. Compared with the two, the interlayer spacing increases by 0.54 nm. Thus, it can be seen that the main reason for the increase in the interlayer spacing of GO after oxidation is that the weakening of the van der Waals force between layers and the expansion of the interlayer spacing are caused by the insertion of a large number of oxygen-containing groups on the surface and the increase of water molecules between layers.

[0065] Figure 6 They are the XRD curves of GO, CNTs-COOH, and D-1. It can be seen from the figure that the diffraction peak of GO is at 2θ = 10.08°, and the diffraction peak of CNTs-COOH has a characteristic peak at 2θ = 25.89°. According to the Bragg equation, the interlayer spacing is calculated to be 0.344 nm. The characteristic peak of D-1 at 2θ = 6.78° in the figure is calculated to have an interlayer spacing of 1.302 nm according to the Bragg equation, and there is a characteristic peak at 2θ = 20.80° with an interlayer spacing calculated to be 0.442 nm according to the Bragg equation. Moreover, the reason for the relatively forward shift of the diffraction peak positions of GO and CNTs-COOH is that after KH550 is used to bridge and graft GO and KH560 is used to bridge and graft CNTs-COOH, the diffraction peaks corresponding to the lattices of KGO for GO and KCNTs-COOH for CNTs-COOH become relatively weak. The main reason is that during the chemical bridging process, due to the insertion of CNTs-COOH, the GO sheets are well exfoliated.

[0066] Figure 7 It is the XRD curve of KGO. It can be seen from the figure that a sharp peak appears at approximately 2θ = 5.78° in the XRD curve of KGO treated with KH550. According to the Bragg equation, the crystal plane spacing is calculated to be 1.527 nm, and the interlayer distance continues to increase. The main reason for the increase in the interlayer distance is that KH550 molecules are inserted between the GO sheets. However, a medium-intensity peak also appears at approximately 11.33° in KGO, and the crystal plane spacing is calculated to be 0.780 nm according to the Bragg equation. The two diffraction peaks of KGO indicate that for GO modified with KH550, a small amount of KH550 molecules are inserted between the GO layers and react with the active groups on the GO surface, growing the molecular chain of KH550 on the surface of the GO graphene sheets through chemical bonds, resulting in an increase in the GO interlayer distance.

[0067] Figure 8XRD curves of D-1, D-2, and D-3 composites prepared by the chemical cross-linking method, respectively. As can be seen from the figure, there are two diffraction peaks at 2θ = 6.78° and 2θ = 20.80°, respectively. According to the Bragg equation, the interlayer spacing at 2θ = 6.78° is 1.302 nm, and the interlayer spacing at 2θ = 20.80° is 0.427 nm.

[0068] Figure 9 XRD curves of E-1, E-2, and E-3 composites prepared by the chemical cross-linking method, respectively. As can be seen from the figure, at 2θ = 6.71° and 2θ = 21.23°, according to the Bragg equation, the interlayer spacings are 0.659 nm and 0.213 nm, respectively. From the synthesized composites, the diffraction peak at 5.78° corresponding to KGO basically disappears, and the diffraction peak of GO becomes wider and flatter. This indicates that the surface of KH560-modified CNTs-COOH (KCNTs-COOH) has active groups. After chemically combining with the GO sheets with active groups on the surface, most CNTs-COOH are inserted into the GO sheets, and the approximate layered structure of KGO modified by KH550 is destroyed, opening the GO sheets, so that most of the GO sheets connected with CNTs-COOH are in a peeled state.

[0069] The resistivity of D-1, D-2, D-3 composites and E-1, E-2, E-3 composites was measured using a Ningbo Ruike powder resistance meter FT-300I. The test results are shown in the following table:

[0070]

[0071] As can be seen from the table, the average resistivity of the graphene / carbon nanotube (GO / CNTs-COOH) composite D-3 (GO: CNT = 5:1) is better than that of D-2 (GO: CNT = 1:1), and better than that of D-1 (GO: CNT = 1:5). The average resistivity of the samples after high-temperature treatment and reduction is lower, and the conductivity is better.

[0072] It is worth mentioning that technical features such as the oil bath reflux device involved in this invention patent application should be regarded as the prior art. The specific structure, working principle, and possible control methods and spatial arrangement methods involved in these technical features can be selected conventionally in the art, and should not be regarded as the invention points of this invention patent. This invention patent will not be further elaborated specifically.

[0073] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field according to the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art should fall within the protection scope determined by the claims.

Claims

1. A preparation method of a graphene / carbon nanotube composite material, characterized in that, It includes the following steps: Step 1: Weigh a certain mass of carboxylated carbon nanotubes and place them in a container. Slowly add a certain amount of the first silane coupling agent, and perform ultrasonic dispersion treatment for 30 min to obtain a dispersion liquid; Step 2: Heat the dispersion liquid in an oil bath reflux device at 80 °C for reflux for 24 h, and continuously stir to obtain a modified KCNTs-COOH solution; Step 3: Weigh a certain mass of graphene oxide and add it to anhydrous ethanol, and perform ultrasonic dispersion treatment for 30 min; Step 4: After the ultrasonic treatment, add the second silane coupling agent, heat and reflux in an oil bath at 80 °C for 8 h, and continuously stir to obtain a modified KGO solution; Step 5: Mix the modified KCNTs-COOH solution and the modified KGO solution and add them to a mixed solution of anhydrous ethanol and deionized water at a ratio of 1:

1. Stir at a constant temperature for 12 hours, dry in a drying oven at 40 °C, and crush; Step 6: Dissolve the dried and crushed powder in anhydrous ethanol, stir at room temperature for 12 h, wash it with anhydrous ethanol solution for multiple times, and then wash it with deionized water for multiple times to obtain a sample; Step 7: Put the sample into a drying oven at 40 °C for drying, crush it to obtain a graphene / carbon nanotube composite material, The first silane coupling agent is γ-glycidoxypropyltrimethoxysilane, and the second silane coupling agent is γ-aminopropyltriethoxysilane.

2. The preparation method of the graphene / carbon nanotube composite material according to claim 1, characterized in that, In Step 1, the weight ratio of carboxylated carbon nanotubes to the first silane coupling agent is 0.16 - 0.79:

100.

3. The preparation method of the graphene / carbon nanotube composite material according to claim 2, wherein In Step 1, the weight ratio of carboxylated carbon nanotubes to the first silane coupling agent is 0.48:

100.

4. The preparation method of the graphene / carbon nanotube composite material according to claim 3, characterized in that, In Step 3 and Step 4, the weight ratio of graphene oxide to the second silane coupling agent is 0.9 - 4.5:

100.

5. The preparation method of the graphene / carbon nanotube composite material according to claim 4, characterized in that, In Step 3 and Step 4, the weight ratio of graphene oxide to the second silane coupling agent is 2.65:

100.

6. The preparation method of the graphene / carbon nanotube composite material according to claim 5, characterized in that, The mass ratio of graphene oxide to carboxylated carbon nanotubes is 1:0.2 - 5.

7. The preparation method of the graphene / carbon nanotube composite material according to claim 6, characterized in that, The mass ratio of graphene oxide to carboxylated carbon nanotubes is 5:

1.

8. A graphene / carbon nanotube composite material, characterized in that, Prepared by the preparation method according to any one of Claims 1 - 7.

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