Carbon nanotube-olefinic carbon composite material and preparation method thereof

Abstract

The invention provides a preparation method of a carbon nanotube-olefinic carbon composite material, which is characterized by comprising the following steps: mixing an olefinic carbon material, an additive and a catalyst, putting the mixture into reaction equipment, and introducing a carbon source to grow a carbon nanotube, the catalyst is a compound or a mixture containing free copper ions, and the carbon nanotubes can be prepared on an olefinic carbon material through catalytic growth by accurately controlling the dispersion uniformity of the copper ions. Copper with general catalytic capability on the growth of the carbon nanotubes theoretically is selected as a catalyst, and the high-yield and high-catalytic-capability growth of the actual carbon nanotubes is realized.

Description

Technical Field

[0001] The present invention relates to the technical fields of carbon nanotube material preparation, composite material preparation, and graphene defect repair, and particularly relates to a preparation method of a carbon nanotube-graphite carbon composite material. Background Art

[0002] Graphene and carbon nanotubes are two highly representative members of the carbon family. Graphene is a single-layer hexagonal honeycomb quasi-two-dimensional carbon material in which carbon atoms are bonded in an sp2 hybridization manner, while carbon nanotubes can be regarded as hollow tubular one-dimensional nanomaterials formed by curling graphene in a certain direction. Both of them are widely used in the fields of energy, aerospace, thermal management, etc. due to their excellent physical, chemical, and mechanical properties. In addition, the vast carbon family also includes single materials such as graphite and carbon black, as well as composite materials composed of any two or more of them.

[0003] In the design of composite materials, the arbitrary combination of different dimensions of zero-dimensional, one-dimensional, and two-dimensional materials can be used as an effective strategy for constructing three-dimensional framework composite materials. The introduction and combination of different-dimensional materials can effectively improve the agglomeration and re-packing problems of themselves and other phase materials. For example, 1) introducing zero-dimensional carbon black SP nanoparticles into two-dimensional graphene powder can effectively inhibit the agglomeration and re-stacking of graphene sheets by virtue of the "Blocking effect" of the nanoparticles; 2) introducing one-dimensional carbon nanotubes into graphene can also effectively improve the problems of easy agglomeration and stacking and difficult dispersion of graphene and carbon nanotubes themselves.

[0004] The traditional and commonly used method for composite materials is the physical mixing method, which relies on the mechanical stirring shear force to make the materials mix evenly. For example, in SCI literature such as "Porous graphene oxide / carbon nanotube hybrid films as interlayer for lithium-sulfur batteries", "Enhanced Electrical Networks of Stretchable Conductors with Small Fraction of Carbon Nanotube / Graphene Hybrid Fillers", "Graphene / carbon nanotube hybrid as a multi-functional interfacial reinforcement for carbon fiber-reinforced composites", and Chinese patent "CN116332168A, A preparation method and application of a graphene-carbon nanotube composite material", graphene and carbon nanotubes are only mixed through simple mechanical stirring. Not only is the mixing and dispersion effect limited, the material interface bonding problem is prominent, and the performance is restricted, but also different types of modifiers, dispersants, stabilizers, viscosity reducers, emulsifiers, etc. need to be introduced during the dispersion of graphene and carbon nanotubes. The introduction of these additives will inevitably have a significant negative impact on the subsequent actual application and performance. However, the direct in-situ growth by chemical vapor deposition (CVD) can avoid the above problems, and the obtained composite material has far better uniformity and performance than the traditional physical mixing method.

[0005] Benefiting from its high carbonophilic catalytic ability, the carbon solubility of typical Ni at 1000 °C is 1.3% atom. Alloys composed of iron, cobalt, nickel and any of the remaining metals with these three elements have become commonly used catalysts for the growth and preparation of carbon nanotubes. For example, SCI literature such as "Large Scale CVD Synthesis of Single-Walled Carbon Nanotubes", "Large-scale synthesis of single-wall carbon nanotubes by catalytic chemical vapor deposition CCVD method", "Roles of Metal-Support Interaction in Growth of Single- and Double-Walled Carbon Nanotubes Studied with Diameter-Controlled Iron Particles Supported on MgO", "The Use of Diatomite as a Catalyst Carrier for the Synthesis of Carbon Nanotubes" have achieved the growth of carbon nanotubes by loading catalysts such as iron and nickel on different carriers. However, due to their strong carbonophilic ability, it is difficult to completely remove the catalysts and the formed metal carbides after growth. In addition, the effective catalytic introduction of such catalysts inevitably introduces foreign impurities such as carriers, and a large number of processes are required for pickling, etching, fumigation and secondary treatment for purification in the later stage. Copper (Cu), due to its weak metal-carbon interaction and a carbon solubility of only 0.04% atom at 1000 °C, is considered a CNT growth catalyst with very weak catalytic ability.

[0006] Finally, Chinese Patent "CN114068927 A, Graphene-Carbon Nanotube Composite Material and Its Preparation Method" successfully carried out the growth and preparation of carbon nanotubes on graphene powder using a fluidized bed device, but there are problems such as high growth temperature, low carbon nanotube growth density and yield, complex process, large amount of catalyst used, impurity residue, and the need for secondary treatment. Summary of the Invention

[0007] In view of the above-mentioned problems, the present invention innovatively introduces a carbon nitride-supported dispersed copper catalyst into the preparation process of carbon nanotubes and graphene-carbon nanotube composite materials. The first aspect of the present invention provides a preparation method of a carbon nanotube-graphene carbon composite material, and the specific scheme includes the following steps: The carbon-based material, additive, and catalyst are mixed and then placed into a reaction device, and a carbon source is introduced to grow carbon nanotubes. The additive is carbon nitride or a reaction precursor for synthesizing carbon nitride.

[0008] Graphitic carbon nitride g-C3N4 can uniformly load and disperse metal catalysts. Meanwhile, the nitrogen element introduced by g-C3N4 can not only effectively facilitate the anchoring of metal ions on the surface of inert graphene, but also, during the high-temperature growth process of carbon nanotubes, carbon nitride will decompose to produce nitrogen-containing active substances, which can effectively improve the catalytic activity of the catalyst, promote the diffusion and migration of carbon atoms, and inhibit the generation of amorphous carbon, thereby realizing the growth of carbon nanotubes and their graphene composites with high yield, high purity, no residual dispersion carrier, low catalyst residue, and no need for secondary pickling, fumigation, and etching treatment, and can achieve a certain degree of defect repair of the graphene substrate.

[0009] The reaction precursors for synthesizing carbon nitride can also achieve the above-mentioned effect of uniformly loading and dispersing metal catalysts. Further, the reaction precursors for synthesizing carbon nitride are one or more of cyanamide, dicyandiamide, urea, thiourea, melamine, cyanuric acid, melamine, cyanuric amide, and cyanuric diamide. The above reaction precursors can form supramolecular structure compounds with metals. The construction of supramolecules can uniformly disperse and anchor metal ions on the supramolecular framework, avoiding the aggregation of ions and the formation of large ion clusters. The construction of supramolecular structure compounds can achieve primary dispersion and anchoring, and then in-situ thermal polycondensation into carbon nitride to achieve secondary dispersion and anchoring, and the catalyst dispersion and anchoring effect is better.

[0010] At the same time, the applicant found that by precisely controlling the degree of uniform dispersion of copper ions, carbon nanotubes can also be catalytically grown and prepared on the carbon-based material.

[0011] Further, the catalyst is a compound or mixture containing free copper ions.

[0012] Further, the catalyst is one or more of copper chloride, copper sulfate, copper nitrate, copper acetate, and the metal organic complex copper acetylacetonate.

[0013] Further, the mixing method of the carbon-based material, additive, and catalyst can be direct mixing, specifically, the additive and catalyst solution are directly added to the carbon-based material together for mechanical stirring and mixing and then drying.

[0014] Further, the mixing method of the carbon-based material, additive, and catalyst can also be indirect mixing, specifically, the additive and catalyst are first mixed and processed to obtain an additive powder loaded with the catalyst, and then the additive powder loaded with the catalyst is added to the carbon-based material.

[0015] Furthermore, the ratio of the carbonaceous material to the additive is 1:1 to 20, preferably 1:1 to 9; the mass of copper element in the catalyst is 0.25 to 20%wt of the carbonaceous material, preferably 0.5 to 10%wt.

[0016] Furthermore, the carbonaceous material is a material with any morphological appearance combined in the sp 2 hybridization mode, such as graphene, flake graphite, expanded graphite, worm graphite; or the carbonaceous material is a material with any morphological appearance combined in the sp 3 hybridization mode, such as carbon black, Ketjen black.

[0017] The second aspect of the present invention provides a carbon nanotube-carbonaceous composite material prepared by the above method.

[0018] The innovation points and beneficial effects of this solution are as follows: Innovatively introduce the carbon nitride-supported dispersed catalyst into the growth process of carbon nanotubes. Metal ions exist in the form of metal-N x -C bonding state within the carbon nitride framework, which can achieve the monodisperse anchoring of metal ions, avoiding the premature aggregation of the catalyst and the disordered generation of large-sized nanoparticles, resulting in the loss of catalytic activity of the catalyst. Heat the graphitic carbon nitride loaded with single-atom metal until the growth temperature of carbon nanotubes. During the heating process, the carbon nitride structure begins to decompose, and the single-atom metal catalyst uniformly dispersed and anchored on the framework begins to be released and polymerized into nanoparticles of a certain uniform size in an orderly manner, thus ensuring the formation of carbon nanotubes with uniform tube diameters and morphologies. Secondly, after high-temperature growth, the carbon nitride will completely decompose without leaving any impurities, with high purity, and there is no need to remove catalyst dispersion carriers such as silica, alumina, magnesia, and diatomaceous earth by pickling and etching as in other methods. On the one hand, the nitrogen-containing active substances released during the decomposition process can inhibit the formation of amorphous carbon, ensuring the high-purity synthesis of carbon nanotubes. On the other hand, the nitrogen-containing substances can also promote the migration and diffusion of carbon atoms on the catalyst surface, maintaining the activity of the catalyst and achieving the high-yield synthesis of carbon nanotubes.

[0019] Using the reaction precursor for synthesizing carbon nitride can also achieve the effect of uniform loading and dispersion of the catalyst. Among them, the reaction precursor can construct a supramolecular structure compound with the metal catalyst to achieve primary dispersion and anchoring, and then in-situ thermally polycondense into carbon nitride to achieve secondary dispersion and anchoring, with better catalyst dispersion and anchoring effect.

[0020] Benefiting from the above supramolecular construction and anchoring dispersion, single-atom anchoring dispersion of carbon nitride, and the decomposition of carbon nitride to release nitrogen-containing substances to inhibit amorphous carbon, promote the diffusion and migration of carbon atoms, and maintain catalytic activity, the amount of catalyst used is extremely small, and there is no need to perform cumbersome fumigation and etching processes to remove the metal catalyst.

[0021] The applicant found that by precisely controlling the dispersion uniformity of copper ions, carbon nanotubes can be catalytically grown on the carbon-ene material. Copper, which is generally considered to have an average catalytic ability for the growth of carbon nanotubes in theory, was selected as the catalyst, and high-yield and high-catalytic-ability growth of actual carbon nanotubes was achieved. Using copper with an extremely low carbon solubility not only does not cause pore etching on the graphene sheets, but also, due to the high catalytic cracking ability of copper for olefins, alkanes, etc. (this is also the principle for generally choosing copper foil as the growth substrate in the CVD preparation of graphene), the carbon active substances released by catalytic cracking can, on the one hand, be used for the growth of the carbon nanotubes themselves, and on the other hand, can effectively repair the structural defects inherent in the carbon-ene material, killing two birds with one stone.

[0022] The synthesis process is simple and universal, the raw materials are widely available, not limited to professional specific synthesis production equipment, and large-scale industrial production can be achieved. Brief Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 SEM images of the carbon nanotube-carbon-ene composites prepared in Example 1 at different magnifications Figure 2 TGA characterization diagram of the carbon nanotube-carbon-ene composites prepared in Example 1 Figure 3 TGA characterization diagram of the reduced graphene oxide raw material used in Example 1 Figure 4 TGA characterization diagram of the TUBALL single-walled carbon nanotubes of OCSiAl Company Figure 5 Raman characterization result diagram of the carbon nanotube-reduced graphene oxide composites prepared in Example 1 Figure 6 SEM images of the carbon nanotube-carbon-ene composites prepared in Example 2 at different magnifications Figure 7 SEM images of the carbon nanotube-carbon-ene composites prepared in Example 3 at different magnifications Figure 8 SEM images of the carbon nanotube-carbon-ene composites prepared in Example 4 at different magnifications Figure 9 SEM images of the carbon nanotube-carbon-ene composites prepared in Example 5 at different magnifications Figure 10SEM images of the carbon nanotube-ene carbon composites prepared in Example 6 at different magnifications Figure 11 SEM images of the carbon nanotube-ene carbon composites prepared in Example 7 at different magnifications Figure 12 SEM images of the carbon nanotube-ene carbon composites prepared in Example 8 at different magnifications Figure 13 SEM images of the carbon nanotube-ene carbon composites prepared in Example 9 at different magnifications Figure 14 SEM images of the carbon nanotube-ene carbon composites prepared in Example 10 at different magnifications Figure 15 SEM images of the carbon nanotube-ene carbon composites prepared in Example 11 at different magnifications Figure 16 SEM images of the carbon nanotube-ene carbon composites prepared in Example 12 at different magnifications Figure 17 SEM images of the carbon nanotube-ene carbon composites prepared in Example 13 at different magnifications Figure 18 SEM images of the carbon nanotube-ene carbon composites prepared in Example 14 at different magnifications Figure 19 SEM images of the carbon nanotube-ene carbon composites prepared in Example 15 at different magnifications Figure 20 SEM images of the carbon nanotube-ene carbon composites prepared in Example 16 at different magnifications Figure 21 SEM images of the carbon nanotube-ene carbon composites prepared in Example 17 at different magnifications Figure 22 SEM images of the carbon nanotube-ene carbon composites prepared in Example 18 at different magnifications Figure 23 SEM images of the carbon nanotube-ene carbon composites prepared in Example 19 at different magnifications Figure 24 SEM images of the carbon nanotube-ene carbon composites prepared in Example 20 at different magnifications Figure 25 TGA characterization diagram of the sample prepared in Comparative Example 1 Figure 26 SEM images of the sample prepared in Comparative Example 1 at different magnifications Figure 27 SEM images of the carbon nanotube-ene carbon composites prepared in Comparative Example 2 at different magnifications Figure 28 SEM images of the carbon nanotube-ene carbon composite materials prepared in Comparative Example 3 at different magnifications Figure 29 SEM images of the carbon nanotube-ene carbon composite materials prepared in Comparative Example 4 at different magnifications Figure 30 SEM images of the carbon nanotube-ene carbon composite materials prepared in Comparative Example 5 at different magnifications Figure 31 SEM images of the carbon nanotube-ene carbon composite materials prepared in Comparative Example 6 at different magnifications Figure 32 SEM images of the carbon nanotube-ene carbon composite materials prepared in Comparative Example 7 at different magnifications Figure 33 SEM images of the carbon nanotube-ene carbon composite materials prepared in Comparative Example 8 at different magnifications Figure 34 SEM images of the samples prepared in Comparative Example 9 at different magnifications Figure 35 SEM images of the carbon nanotube-ene carbon composite materials prepared in Comparative Example 10 at different magnifications Detailed implementation manners

[0025] Next, the technical solutions in the embodiments will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments to be described below are only a 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.

[0026] In the embodiments of the present invention, the statistical method for the yield of carbon nanotubes is as follows: The weighed mass of the ene carbon material before growth is denoted as W1, the weighed amount of the copper compound catalyst is denoted as W2, the mass percentage of copper element in the copper compound catalyst is a, and the mass of the obtained carbon nanotube-ene carbon composite powder after growth is denoted as W3. Then the calculation formula for the yield is: (W3 - W1 - (W2 * a)) / a The reason for calculating the yield of carbon nanotubes in this way is that the additive will completely decompose at high temperature, so its mass is not included in the finally obtained carbon nanotube-ene carbon composite powder. And the copper element-containing compound catalyst will also decompose at high temperature, leaving only copper to catalyze the growth of carbon nanotubes. Example 1

[0027] In this example, the additive is a reaction precursor for synthesizing carbon nitride, and the reaction precursor is specifically urea. And the additive, catalyst and ene carbon material are mixed by an indirect mixing method.

[0028] A preparation method of a carbon nanotube-ene carbon composite material, comprising the following steps: S1. First, weigh 0.6 g of urea and 0.0031 g of copper acetate monohydrate (the mass ratio of copper element in copper acetate monohydrate is 31.83%, so the actual content of copper in 0.0031 g of copper acetate monohydrate is 0.001 g), disperse them in anhydrous ethanol to construct a urea-supramolecular powder by ethanol assistance, and then stir and mix the obtained urea-supramolecular powder with 0.1 g of graphene powder evenly; S2. Fill the powder obtained in step S1 into a container and place it in a reaction device to grow according to a set program. After the growth is completed, cool it to room temperature and take it out. Specifically: Load the powder in step S1 into a crucible and push it into a quartz tube furnace to grow according to a set program. The growth program is more specific as follows: Introduce 100 sccm of hydrogen and 300 sccm of argon, raise the temperature to 550 °C and keep it warm for 30 min under the same gas flow rate. Subsequently, change the flow rate of hydrogen to 5 sccm and the flow rate of argon to 400 sccm, and raise the temperature to 850 °C. After the temperature reaches 850 °C, continue to keep it warm and grow for 30 min. During this period, the introduced gas is 20 sccm of ethylene, 40 sccm of hydrogen and 400 sccm of argon. After the growth is completed, cool it naturally to room temperature and take it out. During this period, only a proper amount of inert gas needs to be introduced for protection. Step 2 of this embodiment has an additional 550 °C heat preservation treatment step compared with directly mixing the materials. The purpose is to allow the carbon nitride precursor to undergo a polycondensation reaction to synthesize carbon nitride. Carbon nitride has rich "nitrogen pots", that is, periodic holes composed of six nitrogen atoms in the plane, which provide rich active trapping sites for capturing metal ions, achieving the effects of uniform dispersion, anchoring and protection.

[0029] The scanning electron microscope image of the carbon nanotube-ene carbon composite material prepared in Example 1 is as Figure 1 shown. It can be seen that carbon nanotubes grow densely and evenly on graphene, forming a carbon nanotube-graphene composite architecture material. The yield of carbon nanotubes is statistically shown in Table 1 under this process as 148.65 / g催化剂 .

[0030] The carbon nanotube-reduced graphene oxide composite material of Example 1 was subjected to thermogravimetric analysis at a heating rate of 5 °C per minute from room temperature to 800 °C in an atmospheric environment under normal pressure. The thermogravimetric analysis TGA characterization results are as Figure 2 shown. Under the same conditions, the thermogravimetric analysis TGA characterization results of the raw material graphene oxide are as Figure 3 shown. The thermogravimetric analysis TGA characterization results of high-level single-walled carbon nanotubes (TUBALL of OCSiAl Company, Russia) in the world are as Figure 4As shown, the DTG curve has only one mass loss peak and no other loss peaks, indicating that the graphene-carbon nanotube composite is a high-purity mixed phase and there are no impurity carbons with low decomposition temperatures. In the TG curve, the measured initial temperature of weight loss is 536.1 °C, proving that the composite material begins to thermally decompose at a temperature of 536.1 °C. There are no fluctuations in the TG curve in the range of 150 °C to 500 °C, and no metal oxidation reaction occurs. In addition, there is a slight mass increase peak near 790 °C in the TG curve, which is mainly due to the decomposition and ablation of the carbon nanotube-reduced graphene oxide composite at this temperature, and the result of the catalyst being oxidized due to the loss of the carbon tube coating protection. This test proves the high-temperature stability of the carbon nanotube-reduced graphene oxide composite and the catalyst in Example 1, mainly due to the use of a low catalyst dosage and the protection of the carbon tube tip shell layer, which is extremely beneficial for applications in scenarios around 500 °C.

[0031] It is also noted that the final residual mass of the carbon nanotube-reduced graphene oxide composite after the ablation test TGA in the atmospheric environment is 6.18%. After removing the 3.8% intrinsic residue, i.e., ash, of the raw material graphene, the actual residual amount of the composite material is 2.38%. The final residual mass of high-level single-walled carbon nanotubes internationally after the ablation test TGA under the same conditions is 3.26%. It can be seen that fewer impurities are introduced during the preparation of the carbon nanotube-reduced graphene oxide composite.

[0032] For the carbon nanotube-reduced graphene oxide composite in Example 1, an ICP test was carried out, and the measured content of copper element is 0.5217% of the total mass of the carbon nanotube-graphene composite. Thus, it can be seen that the residual amount of the catalytic metal in the composite material is small.

[0033] The Raman characterization result picture of the carbon nanotube-reduced graphene oxide composite in Example 1 is as Figure 5 shown. It can be seen that the D peak at 1352.3 cm -1 , the G peak at 1580 cm -1 , and the 2D peak at 2687.2 cm -1 are located respectively. Compared with the raw material reduced graphene oxide, it can be found that for the carbon nanotube-reduced graphene oxide composite after growing carbon nanotubes under the conditions of Example 1, the I D / I G decreases from 0.998 to 0.743, indicating that some foreign defects or structural defects of the reduced graphene oxide have been repaired to a certain extent. Example 2

[0034] In this embodiment, different from Embodiment 1, the additive, catalyst and carbon-ene material are mixed by the direct mixing method.

[0035] S1. Directly and simultaneously mix and stir 0.1 g of graphene powder, 0.6 g of urea and an ethanol solution containing 0.0031 g of copper acetate monohydrate, and then dry to volatilize the ethanol. S2. The steps are the same as S2 in Embodiment 1.

[0036] The scanning electron microscope image of the carbon nanotube-carbon-ene composite material prepared in Embodiment 2 is as Figure 6 shown. It can be seen that carbon nanotubes grow densely and uniformly on graphene, forming a carbon nanotube-graphene composite architecture material. As can be seen from Table 1, the yield of carbon nanotubes under this growth condition is 126.47 / g催化剂 . Embodiment 3

[0037] Different from Embodiment 1, the carbon-ene material graphene, the additive carbon nitride and the catalyst copper acetate monohydrate are mixed in an indirect mixing manner.

[0038] S1. First, prepare carbon nitride loaded with copper catalyst: First, weigh 0.6 g of urea and 0.0031 g of copper acetate monohydrate and disperse them in absolute ethanol to assist in constructing supramolecular powder by ethanol. Place the constructed supramolecular powder in a tubular furnace, heat it to 550 °C under an inert atmosphere and keep it warm for 30 min, then naturally cool it to room temperature under an inert atmosphere and take it out and crush it into powder. Finally, obtain carbon nitride loaded with copper catalyst obtained by thermal polycondensation treatment of the supramolecular powder; Stir and mix the obtained carbon nitride loaded with copper catalyst and 0.1 g of reduced graphene oxide powder evenly. S2. Fill the powder into a container and place it in a reaction device to grow according to a set program. After the growth is completed, cool it to room temperature and take it out. Specifically: Load the powder in step S1 into a crucible and push it into a quartz tubular furnace to grow according to a set program. The growth program is more specific as follows: Introduce 100 sccm of hydrogen and 300 sccm of argon. When the temperature rises to 550 °C, immediately change the hydrogen flow rate to 5 sccm and the argon flow rate to 400 sccm, and continue to heat up to 850 °C. After the temperature reaches 850 °C, continue to keep it warm and grow for 30 min. During this period, the introduced atmosphere is 20 sccm of ethylene, 40 sccm of hydrogen and 400 sccm of argon. After the growth is completed, naturally cool it to room temperature under an inert atmosphere and take it out.

[0039] The scanning electron microscope image of the carbon nanotube-carbon-ene composite material prepared in Embodiment 3 is as Figure 7As shown, it can be seen that carbon nanotubes grow densely and uniformly on graphene, forming a carbon nanotube-graphene composite architecture material. The yield of carbon nanotubes under this process is shown in Table 1 as 115.6 / g催化剂 . Example 4

[0040] Different from Example 3, the graphene of the ene-carbon material, the additive carbon nitride, and the catalyst copper acetate monohydrate are mixed in a direct mixing manner.

[0041] S1. Mix the graphene of the ene-carbon material, the additive carbon nitride, and the catalyst copper acetate monohydrate in a certain proportion and manner, specifically in a direct mixing manner: directly mix and stir 0.1 g of reduced graphene oxide powder, 0.1 g of carbon nitride, and an ethanol solution containing 0.0031 g of copper acetate monohydrate at the same time, and then dry to volatilize the ethanol; S2. Fill the powder into a container and place it in a reaction equipment to grow according to a set program. After the growth is completed, cool it to room temperature and take it out. Specifically: load the powder in step S1 into a crucible and push it into a quartz tube furnace to grow according to a set program. The growth program is more specific as follows: introduce 100 sccm of hydrogen and 300 sccm of argon. When the temperature rises to 550 °C, immediately change the hydrogen flow rate to 5 sccm and the argon flow rate to 400 sccm, and continue to heat up to 850 °C. After the temperature reaches 850 °C, continue to hold the temperature for growth for 30 min. During this period, the atmosphere introduced is 20 sccm of ethylene, 40 sccm of hydrogen, and 400 sccm of argon. After the growth is completed, naturally cool it to room temperature in an inert atmosphere and take it out.

[0042] The scanning electron microscope images of the carbon nanotube-ene-carbon composite material prepared in Example 3 are as Figure 8 shown. It can be seen that carbon nanotubes grow densely and uniformly on graphene, forming a carbon nanotube-graphene composite architecture material. The yield of carbon nanotubes under this process is shown in Table 1 as 100.08 / g催化剂 .

[0043] Examples 5-6 What is different between Examples 5-6 and Examples 1-2 respectively is that the additive used is a reaction precursor for synthesizing carbon nitride, and the reaction precursor is specifically 0.5 g of cyanamide. The other steps of Example 5 are the same as those of Example 1, and the other steps of Example 6 are the same as those of Example 2.

[0044] Example 5 uses an indirect mixing method for mixing; Example 6 uses a direct mixing method for mixing.

[0045] The scanning electron microscope images of the carbon nanotube-ene-carbon composite material prepared in Examples 5-6 are as Figure 9 - 10as shown

[0046] Examples 7 - 8 Examples 7 - 8 are different from Examples 1 - 2 in that the additive used is a reaction precursor for synthesizing carbon nitride, and the reaction precursor is specifically 0.45 g of dicyandiamide. Other steps of Example 7 are the same as those of Example 1, and other steps of Example 8 are the same as those of Example 2.

[0047] Example 7 uses the indirect mixing method for mixing; Example 8 uses the direct mixing method for mixing.

[0048] Scanning electron microscope pictures of the carbon nanotube - graphene carbon composite materials prepared in Examples 7 - 8 are as Figure 11 - 12 shown

[0049] From Examples 1 - 8, it can be known that the efficiency of growing carbon nanotubes by the indirect mixing method is better than that of direct mixing: The applicant speculates that this is because in the direct mixing method, the catalyst cannot be effectively loaded on the additive entirely, but a part is directly mixed into the graphene sheets, and this part will aggregate into large nanoparticles during the heating growth process, losing catalytic activity, and the effective usage ratio of the catalyst is relatively reduced, thus also resulting in a relatively lower growth efficiency of carbon nanotubes. However, it should be noted that the carbon nanotube yields of both the direct mixing and indirect mixing methods can reach 100 g / g催化剂 Above, it still has obvious advantages compared with the dispersion method of the silica - supported catalyst. Example 9

[0050] Example 9 is different from Example 1 in that the additive used is a reaction precursor for synthesizing carbon nitride, and the reaction precursor is specifically 0.6 g of thiourea.

[0051] S1. Example 9 uses the indirect mixing method for mixing; S2. It is the same as step S2 in Example 1.

[0052] Scanning electron microscope pictures of the carbon nanotube - graphene carbon composite material prepared in Example 9 are as Figure 13 shown Example 10

[0053] Example 10 is different from Example 1 in that the additive used is a reaction precursor for synthesizing carbon nitride, and the reaction precursor is specifically 0.3 g of melamine.

[0054] S1. Example 10 uses the indirect mixing method for mixing; S2. It is the same as step S2 in Example 1.

[0055] The scanning electron microscope image of the carbon nanotube-ene carbon composite material prepared in Example 10 is as shown in Figure 14 the following figure. Example 11

[0056] The difference between Example 11 and Example 1 is that the additive used is a reaction precursor for synthesizing carbon nitride, and the reaction precursor is specifically 0.3 g of cyanuric acid.

[0057] S1. In Example 11, the indirect mixing method is adopted for mixing; S2. It is consistent with the S2 step in Example 1.

[0058] The scanning electron microscope image of the carbon nanotube-ene carbon composite material prepared in Example 11 is as shown in Figure 15 the following figure. Example 12

[0059] The difference between Example 12 and Example 1 is that the additive used is a reaction precursor for synthesizing carbon nitride, and the reaction precursor is specifically 0.4 g of cyanuric amide.

[0060] S1. In Example 12, the indirect mixing method is adopted for mixing; S2. It is consistent with the S2 step in Example 1.

[0061] The scanning electron microscope image of the carbon nanotube-ene carbon composite material prepared in Example 12 is as shown in Figure 16 the following figure. Example 13

[0062] The difference between Example 13 and Example 1 is that the additive used is a reaction precursor for synthesizing carbon nitride, and the reaction precursor is specifically 0.45 g of cyanuric diamide.

[0063] S1. In Example 13, the indirect mixing method is adopted for mixing; S2. It is consistent with the S2 step in Example 1.

[0064] The scanning electron microscope image of the carbon nanotube-ene carbon composite material prepared in Example 13 is as shown in Figure 17 the following figure. Example 14

[0065] The difference between Example 14 and Example 1 is that the additive used is a reaction precursor for synthesizing carbon nitride, and the reaction precursor is specifically 0.2 g of melamine.

[0066] S1. In Example 14, the indirect mixing method is adopted for mixing; S2. It is consistent with the S2 step in Example 1.

[0067] The scanning electron microscope image of the carbon nanotube-ene carbon composite material prepared in Example 14 is as shown in Figure 18 the following figure.

[0068] From Examples 1-14, it can be obtained that according to different additives, the ratio of the ene carbon material to the additive also varies. Generally speaking, the ratio of the ene carbon material to the additive is 1:1 to 20, preferably 1:1 to 9. Example 15

[0069] Different from Example 1, the catalyst used is copper nitrate trihydrate, and the weighed amount is 0.0038 g (the mass fraction of copper element in copper nitrate trihydrate is 37.81%, so the actual content of copper in 0.0038 g of copper nitrate trihydrate is 0.001 g). Other steps are the same as those in Example 1.

[0070] S1. In Example 15, indirect mixing is adopted for mixing: S2. The same as step S2 in Example 1.

[0071] The scanning electron microscope image of the carbon nanotube-ene carbon composite material prepared in Example 15 is as shown in Figure 19 the following figure. Example 16

[0072] Different from Example 10, the catalyst used is copper chloride dihydrate, and the weighed amount is 0.0027 g. Other steps are the same as those in Example 10.

[0073] S1. In Example 16, indirect mixing is adopted for mixing: First, weigh 0.3 g of melamine and 0.0027 g of copper chloride dihydrate and disperse them in absolute ethanol to construct melamine-copper supramolecular powder by ethanol assistance. Then, stir and mix the obtained melamine-copper supramolecular powder with 0.1 g of graphene powder evenly; S2. The same as step S2 in Example 1.

[0074] The scanning electron microscope image of the carbon nanotube-ene carbon composite material prepared in Example 16 is as shown in Figure 20 the following figure. Example 17

[0075] Different from Example 13, the catalyst used is copper acetylacetonate, and the weighed amount is 0.0041 g. Other steps are the same as those in Example 13.

[0076] S1. In Example 17, indirect mixing is adopted for mixing: S2. The same as step S2 in Example 1.

[0077] The scanning electron microscope image of the carbon nanotube-ene carbon composite material prepared in Example 17 is as follows Figure 21 shown.

[0078] From Example 1 and Examples 15-17, we can see that different catalysts can also catalyze the growth of carbon nanotubes on the ene carbon material. Therefore, it can be known that the effective element in the catalyst is copper. Example 18

[0079] A method for preparing a carbon nanotube-ene carbon composite material includes the following steps: S1. Reduce the amount of the catalyst to half of the original amount, and the rest is the same as in Example 1; S2. The same as in Example 1; The scanning electron microscope image of the carbon nanotube-ene carbon composite material prepared in Example 18 is as follows Figure 22 shown. Example 19

[0080] A method for preparing a carbon nanotube-ene carbon composite material includes the following steps: S1. Increase the amount of the catalyst to 5 times the original amount, that is, 0.0155 g, and the rest is the same as in Example 1; S2. The same as in Example 1; The scanning electron microscope image of the carbon nanotube-ene carbon composite material prepared in Example 19 is as follows Figure 23 shown. Example 20

[0081] A method for preparing a carbon nanotube-ene carbon composite material includes the following steps: S1. Increase the amount of the catalyst to 10 times the original amount, that is, 0.031 g, and the rest is the same as in Example 1; S2. The same as in Example 1; The scanning electron microscope image of the carbon nanotube-ene carbon composite material prepared in Example 20 is as follows Figure 24 shown.

[0082] From Examples 18-20, we can know that when the addition amount of the catalyst is increased by 10 times, the yield can still reach 96.42.

[0083] Comparative Example 1 A method for preparing a carbon nanotube-ene carbon composite material includes the following steps: S1. Except that urea is not added in step S1, that is, 0.0031 g of copper acetate monohydrate catalyst is directly dissolved in an appropriate amount of ethanol and stirred and mixed with graphene for drying, and the rest of the steps and parameters are the same as in Example 1; S2. The same as in Example 1; Compared with Example 1, the difference between Comparative Example 1 and it is that urea is not added. From Figure 25 it can be seen that the DTG curve in the TGA result of Comparative Example 1 without urea has two obvious mass loss peaks. The one at 525.6 °C corresponds to the decomposition loss peak of amorphous carbon, and the one at 563.1 °C is the 3 main decomposition loss peak. In addition, there is an obvious 2.39% mass increase in its TG curve after 200 °C, which is mainly attributed to the oxidation of the copper catalyst. More intuitively, from 2 the SEM picture of Comparative Example 1 in Figure 26 it can be seen that there is almost no obvious carbon nanotube structure formed on the graphene. The catalyst is not protected by the carbon nanotube tip sheath and is in an exposed state, and it is easily oxidized under the high-temperature atmospheric atmosphere during the TGA test. Although the yield of Comparative Example 1 in Table 1 is 137.66, which is not much different from 148.65 of Example 1, combining Figure 26 with Figure 1 the SEM comparison in Figure 25 and the TGA analysis of Comparative Example 1 in 3 and the yield comparison between Example 1 and Comparative Example 1 in Table 1, in fact, the contribution of the yield of Comparative Example 1 comes from the formation of amorphous carbon. Due to the lack of urea as an additive, on the one hand, the dispersion and anchoring of the catalyst are lost. During the heating and growth process, the catalyst metal ions directly change from ionic clusters to large-sized nanoparticles step by step, losing the ability to catalyze the growth of carbon nanotubes. On the other hand, due to the lack of additive urea, there are no effective nitrogen-containing fragments in the atmosphere to act as amorphous carbon inhibitors to protect the activity of the catalyst and act as growth promoters to promote the migration and diffusion of carbon atoms on the catalyst surface, thereby increasing the yield.

[0084] Comparative Example 2 Silica was used as a dispersant to load and disperse the catalyst for growth. The specific steps are as follows: S1: First, weigh 0.025 g of nanoscale silica particles with a particle size of 15 nm, then weigh 0.0031 g of copper acetate monohydrate, disperse the two in absolute ethanol, and stir and mix the mixture with 0.1 g of graphene powder and dry it; S2: Fill the powder into a container and place it in a reaction device to grow according to a set program. After the growth is completed, cool it to room temperature and take it out. Specifically: Load the powder in step S1 into a crucible and push it into a quartz tube furnace to grow according to a set program. The growth program is more specific as follows: Introduce 300 sccm of argon gas to raise the temperature to 700 °C. After the temperature reaches 700 °C, change the gas introduced to 5 sccm of hydrogen gas and 400 sccm of argon gas and raise the temperature to 850 °C. After the temperature reaches 850 °C, keep it warm for 5 min first. After 5 min, introduce 20 sccm of ethylene, 40 sccm of hydrogen gas and 400 sccm of argon gas and continue to keep it warm for growth for 30 min. After the growth is completed, cool it naturally to room temperature in an inert atmosphere and take it out.

[0085] Comparative Example 3 Use silica as a dispersant to load and disperse the catalyst for growth. The specific steps are as follows: S1: Change the weighed amount of nanoscale silica to 0.05 g, and the rest is the same as Comparative Example 2; S2: The same as Comparative Example 2; Comparative Example 4 Use silica as a dispersant to load and disperse the catalyst for growth. The specific steps are as follows: S1: Change the weighed amount of nanoscale silica to 0.1 g, and the rest is the same as Comparative Example 2; S2: The same as Comparative Example 2; Comparative Example 5 Use silica as a dispersant to load and disperse the catalyst for growth. The specific steps are as follows: S1: Change the weighed amount of nanoscale silica to 0.2 g, and the rest is the same as Comparative Example 2; S2: The same as Comparative Example 2; The scanning electron microscope pictures of the carbon nanotube-graphene-carbon composite materials prepared in Comparative Examples 2-5 are respectively as Figure 27 - 30 shown. It can be seen that as long as the dispersion uniformity of copper ions is controlled, the silica nanoparticles loaded with the dispersed catalyst can also effectively grow carbon nanotubes. However, the morphology of the carbon nanotubes grown by using silica as a dispersant is relatively disordered, the size distribution is chaotic, and even with the increase of the silica addition amount, the dispersion performance is not effectively improved, but the tube diameter becomes thicker instead. This is attributed to the fact that with the increase of silica nanoparticles, the probability of their agglomeration becomes greater and greater, resulting in the catalyst agglomerating together to form large particles, thus generating short tubes with large diameters. In addition, this silica dispersion strategy will also bring an obvious problem, that is, the introduction of silica will become an impurity, and after the growth is completed, it is necessary to perform secondary treatment of pickling and etching to remove silica to obtain the final graphene-carbon nanotube composite material, which is time-consuming, laborious and ineffective.

[0086] Comparative Example 6 A preparation method of a carbon nanotube-ene carbon composite material, comprising the following steps: S1. Expand the amount of the catalyst to 20 times the original amount, that is, 0.062 g, and the rest is the same as in Example 1; S2. The same as in Example 1; Comparative Example 7 A preparation method of a carbon nanotube-ene carbon composite material, comprising the following steps: S1. Expand the amount of the catalyst to 50 times the original amount, that is, 0.155 g, and the rest is the same as in Example 1; S2. The same as in Example 1.

[0087] The scanning electron microscope pictures of the carbon nanotube-ene carbon composite materials prepared in Comparative Examples 6-7 are respectively as Figure 31 - 32 shown. As the amount of the catalyst added is excessive, the diameter of the carbon nanotubes becomes significantly thicker. When the addition amount is expanded to 50 times, its tube diameter becomes 200 nm, the length becomes shorter, the tube length < 700 nm, and the yield is reduced to less than 22.5. It can be seen from this that the growth state of the carbon nanotubes is not only related to the particle size of the catalyst, but also related to the amount of the catalyst used. For metallic copper as the catalyst, the increase in the catalyst also means an increase in the probability of aggregation and growth of the catalyst. After the catalyst aggregates and deactivates, it instead makes the tube diameter of the carbon nanotubes thicker and the length shorter. When the tube diameter of the carbon nanotubes reaches the nanometer level of hundreds, its structural characteristics will become hard and brittle, its winding property is weak, its ability to form a diffusion conductive network is poor, and its buffering performance is poor, and it is easy to peel off during the application process.

[0088] Comparative Example 8 A preparation method of a carbon nanotube-ene carbon composite material, comprising the following steps: S1. Expand the amount of the additive urea to 4 times the original amount, that is, 2.4 g, and the rest is the same as in Example 1; S2. The same as in Example 1; The scanning electron microscope picture of the carbon nanotube-ene carbon composite material prepared in Comparative Example 8 is as Figure 33 shown, and the yield of the carbon nanotubes is reduced to 48.56 g / g催化剂 .

[0089] When the additive is in excess, excessive nitrogen-containing substances are released, which will cause etching damage to the graphene, and instead, carbon nanotubes cannot grow efficiently.

[0090] Comparative Example 9 A preparation method of a carbon nanotube-ene carbon composite material, comprising the following steps: S1. Change the catalyst to iron(III) chloride hexahydrate, and the weighed amount is 0.0048 g, and the rest is the same as in Example 1; S2. The same as in Example 1; The scanning electron microscope image of the carbon nanotube-ene carbon composite prepared in Comparative Example 9 is as Figure 34 shown. The growth of carbon nanotubes cannot be found in the SEM image.

[0091] Although iron element can theoretically catalyze the growth of carbon nanotubes as a catalyst, it requires a large amount of doping to have a catalytic effect. Using the same mass of iron element as copper element as a catalyst does not have a catalytic effect.

[0092] Comparative Example 10 A preparation method of a carbon nanotube-ene carbon composite includes the following steps: S1. Change the catalyst to ferric chloride hexahydrate and copper acetate monohydrate, and the ratio of the two is 1:3, that is, weigh 0.0012 g of ferric chloride hexahydrate and 0.0024 g of copper acetate monohydrate, and the rest is the same as in Example 1; S2. The same as in Example 1; The scanning electron microscope image of the carbon nanotube-ene carbon composite prepared in Comparative Example 10 is as Figure 35 shown. Doping a small amount of a catalyst containing copper element can catalyze the growth of carbon nanotubes.

[0093] The carbon nanotube yield results corresponding to Examples 1-20 and Comparative Examples 1-10 are shown in the following table:

[0094] In summary, the present invention innovatively introduces supramolecular construction and carbon nitride-supported dispersed catalysts into the preparation process of carbon nanotubes and graphene-carbon nanotube composites, and selects copper, which generally has a general catalytic ability for the growth of carbon nanotubes theoretically, as a catalyst and realizes the growth of carbon nanotubes with high yield and high catalytic ability. Carbon nitride can significantly improve the dispersion of the catalyst, and the introduced nitrogen element can effectively facilitate the anchoring of metal atoms on the surface of inert graphene. In addition, an appropriate amount of nitrogen-containing active substances generated by the decomposition of carbon nitride during the high-temperature growth process can effectively improve the catalytic activity of the catalyst, promote the diffusion and migration of carbon atoms, and inhibit the generation of amorphous carbon, thereby realizing the growth of carbon nanotubes and their graphene composites with high yield, high purity, no residual dispersion carrier, low catalyst residue, and no need for secondary pickling, fumigation, and etching treatment, and can repair certain defects of the graphene substrate to a certain extent. The synthesis route provided by this scheme has simple and universal technology, wide range of raw material sources, economy, is not limited by professional specific synthesis production equipment, and can realize large-scale industrial production.

[0095] In the above embodiments, the descriptions of each embodiment have their own emphases. For the parts not detailedly described in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0096] As described above, the above are specific embodiments of the present invention. However, the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A preparation method of a carbon nanotube-ene carbon composite material, characterized in that It includes the following steps: Mix the carbonaceous material, additive, and catalyst, then place them into a reaction device and introduce a carbon source to grow carbon nanotubes. The additive is carbon nitride or a reaction precursor for synthesizing carbon nitride.

2. A method for preparing a carbon nanotube-graphite carbon composite material as described in claim 1, characterized in that, The catalyst is a compound or mixture containing free copper ions.

3. A method for preparing a carbon nanotube-graphite carbon composite material as described in claim 1, characterized in that, The ratio of the carbonaceous material to the additive is 1:1 to 20, preferably 1:1 to 9.

4. A method for preparing the carbon nanotube-graphite carbon composite material as described in claim 2, characterized in that, The mass of copper element in the catalyst is 0.25 to 20%wt of the carbonaceous material, preferably 0.5 to 10%wt.

5. A method for preparing a carbon nanotube-graphite carbon composite material as described in claim 2, characterized in that, The catalyst includes one or more of copper chloride, copper sulfate, copper nitrate, copper acetate, and the metal organic complex copper acetylacetonate.

6. A method for preparing a carbon nanotube-ene carbon composite material as described in claim 1, characterized in that, The reaction precursor for synthesizing carbon nitride is one or more of cyanamide, dicyandiamide, urea, thiourea, melamine, cyanuric acid, melamine, cyanuric amide, and cyanuric diamide.

7. A method for preparing the carbon nanotube-graphite carbon composite material as described in claim 1, characterized in that, The grown carbon nanotubes are single-walled carbon nanotubes and / or multi-walled carbon nanotubes.

8. A method for preparing a carbon nanotube-ene carbon composite material according to any one of claims 1-7, characterized in that, The mixing method of the carbonaceous material, additive, and catalyst is direct mixing, specifically, the additive and the catalyst solution are directly added to the carbonaceous material together for mechanical stirring and mixing, and then drying.

9. A method for preparing a carbon nanotube-graphite carbon composite material according to any one of claims 1-7, characterized in that, The mixing method of the carbonaceous material, additive, and catalyst is indirect mixing, specifically, first mix the additive and the catalyst to obtain an additive powder loaded with the catalyst, and then add the additive powder loaded with the catalyst to the carbonaceous material.

10. A carbon nanotube-ene carbon composite material, characterized in that, The carbon nanotube-carbonaceous material composite is prepared by the preparation method described in any one of claims 1-9.

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