A highly conductive flexible rGO@carbon cloth, preparation method and application thereof

Abstract

The present invention provides a highly conductive flexible rGO@carbon cloth, a preparation method and application thereof. The highly conductive flexible rGO@carbon cloth comprises a carbon cloth and reduced graphene oxide loaded on the carbon cloth, wherein the carbon cloth is composed of woven biomass carbon fibers, and the biomass carbon fibers have a hollow structure. The rGO@carbon cloth is prepared by using biomass natural fibers as raw materials to prepare flexible carbon cloth, and loaded with reduced graphene oxide, so that the carbon cloth has a highly conductive graphene network, which improves its conductivity while ensuring flexibility. According to research, the rGO@carbon cloth has excellent flexibility, will not break after bending, and has excellent electromagnetic shielding effect, and the electromagnetic shielding effectiveness can reach 22dB.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional carbon fiber preparation, and specifically relates to a highly conductive and flexible rGO@carbon cloth, a preparation method and application thereof. Background Art

[0002] With the development and progress of flexible electronic technology, flexible materials have generated a large demand in the fields of flexible display, implantable medical, portable and wearable. Some functional materials used in complex morphologies also require materials to have flexible and processable characteristics. In addition, carbon materials have the advantages of good biocompatibility, high physical strength, good conductivity, environmental friendliness and low cost. Flexible carbon-based materials have many novel features such as bendability, foldability, flexibility and shape deformation, and can be used in the fields of supercapacitor electromagnetic and electromagnetic protection functions.

[0003] Flexible carbon-based materials mainly include several carbon materials such as graphene, carbon nanotubes, carbon fiber polymers or fabric carbon. Among them, flexible carbon materials prepared from graphene, carbon nanotubes or carbon fiber polymers require the introduction of binders, and the carbon cloth molding method is complicated, and the raw material manufacturing cost is high. In comparison, biomass materials are renewable, cheap, easy to obtain, and have rich and adjustable natural ion transport channels and heteroatoms. They also have three-dimensional macroporous scaffold structures and flexibility, which provide great possibilities for the development of cheap and efficient flexible materials. However, the conductivity of a single biomass material is low, and its conductivity needs to be further improved in order to be applied to the fields of supercapacitor electromagnetic and electromagnetic protection functions. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a highly conductive flexible rGO@carbon cloth, a preparation method and an application thereof. The highly conductive flexible rGO@carbon cloth is prepared by using biomass natural fiber as a raw material to prepare a flexible carbon cloth, and loaded with reduced graphene oxide, so that the carbon cloth has a highly conductive graphene network, which improves its conductivity while ensuring flexibility.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a highly conductive and flexible rGO@carbon cloth (rGO is the abbreviation of reduced graphene oxide), comprising a carbon cloth and reduced graphene oxide supported on the carbon cloth;

[0007] The carbon cloth is composed of woven biomass carbon fibers, and the biomass carbon fibers have a hollow structure.

[0008] Preferably, the biomass carbon fiber includes tree cotton carbon fiber and cotton carbon fiber.

[0009] Preferably, the mass ratio of the tree cotton carbon fiber to the cotton carbon fiber is (1-7):(9-3).

[0010] Preferably, the mass ratio of the carbon cloth to the reduced graphene oxide is 1 g:(1-8) mg.

[0011] In a second aspect, the present invention provides a method for preparing highly conductive and flexible rGO@carbon cloth, comprising the following steps:

[0012] (1) Provide carbon cloth;

[0013] (2) etching the carbon cloth, mixing it with a graphene oxide dispersion and ultrasonicating it to obtain a carbon cloth loaded with graphene oxide;

[0014] (3) The graphene oxide-loaded carbon cloth is mixed with a reducing agent / graphene oxide dispersion and then subjected to a temperature treatment to obtain the highly conductive and flexible rGO@carbon cloth.

[0015] Preferably, the carbon cloth is obtained by weaving biomass fibers and then subjecting them to carbonization treatment.

[0016] Preferably, the carbonization treatment is specifically: heating to 600-1200° C. at a rate lower than 2° C. / min and then keeping the temperature for 1-6 hours.

[0017] Preferably, the biomass fibers include tree cotton fibers and cotton fibers in a mass ratio of (1-7):(9-3).

[0018] Preferably, the solvent of the graphene oxide dispersion is water, and the concentration is 2-10 mg / mL.

[0019] Preferably, in step (2), the ratio of the carbon cloth to the graphene oxide dispersion is 1 g: (5-50) mL.

[0020] Preferably, the reducing agent / graphene oxide dispersion is obtained by mixing a reducing agent and a graphene oxide dispersion.

[0021] Preferably, the reducing agent is selected from any one or more of L-ascorbic acid, phenylhydrazine, hydrazine hydrate or hydroiodic acid.

[0022] Preferably, the ratio of the reducing agent to the graphene oxide dispersion is (10-100) mg:1 mL.

[0023] Preferably, in step (3), the ratio of the carbon cloth to the reducing agent / graphene oxide dispersion is 1 g: (5-20) mL.

[0024] Preferably, the temperature of the heating treatment is 60-100° C. and the time is 1-10 hours.

[0025] In a third aspect, the present invention provides an electromagnetic shielding material, including the highly conductive and flexible rGO@carbon cloth involved in the above technical solution.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention provides a highly conductive and flexible rGO@carbon cloth, which is first prepared from low-cost, hollow-structured biomass fibers as raw materials to obtain carbon cloth. The hollow structure of the biomass carbon fibers can ensure the lightweight characteristics of the carbon cloth material on the one hand, and can also facilitate the introduction of graphene oxide materials into the biomass carbon fibers on the other hand. After the graphene oxide is reduced, a highly conductive graphene network is formed on the surface and inside of the carbon cloth, which can ensure that the carbon cloth has flexibility while achieving improved conductivity. The highly conductive and flexible rGO@carbon cloth can exhibit excellent characteristics in application fields such as electromagnetic shielding and electrode materials. According to research, it has excellent flexibility, will not break after bending, and has an electromagnetic shielding effectiveness of up to 22dB, which has an excellent electromagnetic shielding effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a SEM image of the carbon cloth obtained in step (2) of Example 1 at a low magnification;

[0029] Figure 2 This is a SEM image of the carbon cloth obtained in step (2) of Example 1 at a high magnification;

[0030] Figure 3 This is the SEM image of rGO@carbon cloth obtained in Example 1;

[0031] Figure 4 This is a macroscopic schematic diagram of the bending of the rGO@carbon cloth obtained in Example 1;

[0032] Figure 5 This is a graph showing the electromagnetic shielding performance of rGO@carbon cloth obtained in Example 1;

[0033] Figure 6 This is the electromagnetic shielding performance diagram of rGO@carbon cloth obtained in Comparative Example 1. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In view of the problems of complex molding methods and high raw material manufacturing costs of flexible carbon-based materials in the prior art, the present invention provides a highly conductive flexible rGO@carbon cloth, including carbon cloth and reduced graphene oxide loaded on the carbon cloth. In the present invention, the carbon cloth is composed of woven biomass carbon fibers, and the biomass carbon fibers have a hollow structure, which includes tree cotton carbon fibers and cotton carbon fibers. In some embodiments of the present invention, the mass ratio of the tree cotton carbon fibers to the cotton carbon fibers is (1-7): (9-3), preferably 7: 3. In the present invention, the tree cotton carbon fibers and the cotton carbon fibers are obtained by carbonizing tree cotton fibers and cotton fibers, respectively. The tree cotton fibers are a new type of biomass fiber with a hollow morphology. The cotton fibers also have a hollow morphology, and their wall thickness is thicker than that of tree cotton fibers, and the hollowness is relatively low, but their cost is lower than that of tree cotton fibers, and they are easy to obtain. Therefore, considering the comprehensive cost and textile process, the tree cotton fibers and cotton fibers are used as raw materials to prepare carbon cloth, which is beneficial to improving the lightweight characteristics of the carbon cloth material and is more conducive to the further loading of the graphene oxide material. In the present invention, the reduced graphene oxide can be loaded on the surface of the carbon cloth or inside the carbon cloth (including the gaps between the carbon fibers of the carbon cloth and inside the hollow structure of the carbon cloth). In some embodiments of the present invention, the mass ratio of the carbon cloth to the reduced graphene oxide is 1 g: (1 to 8) mg.

[0036] The highly conductive and flexible rGO@carbon cloth provided by the present invention is first prepared from low-cost, hollow-structured biomass fibers as raw materials to obtain carbon cloth, and then loaded with reduced graphene oxide to form a highly conductive graphene network on the surface and inside of the carbon cloth, thereby ensuring the flexibility of the carbon cloth while improving its conductivity, and can exhibit excellent properties in application fields such as electromagnetic shielding and electrode materials.

[0037] The present invention pre-selects a flexible cloth woven from biomass fiber material as the initial raw material, and obtains the flexible carbon cloth after high-temperature carbonization treatment. In order to obtain the high conductivity of the flexible carbon cloth, a uniformly dispersed graphene oxide component is further introduced into the interior and surface of the carbon cloth, and finally the graphene oxide is reduced to obtain the target product of the present invention, the highly conductive flexible rGO@carbon cloth. In some embodiments of the present invention, the preparation method of the highly conductive flexible rGO@carbon cloth specifically includes the following steps:

[0038] (1) Provide carbon cloth;

[0039] (2) etching the carbon cloth, mixing it with a graphene oxide dispersion and ultrasonicating it to obtain a carbon cloth loaded with graphene oxide;

[0040] (3) The graphene oxide-loaded carbon cloth is mixed with a reducing agent / graphene oxide dispersion and then subjected to a temperature treatment to obtain the highly conductive and flexible rGO@carbon cloth.

[0041] According to the present invention, a carbon cloth is first provided. In some embodiments of the present invention, the carbon cloth is obtained by weaving biomass fibers and then carbonizing them. The present invention has no particular restrictions on weaving, and it can be carried out according to the technical means familiar to those skilled in the art. In some embodiments of the present invention, the mass ratio of tree cotton fiber to cotton fiber is (1-7): (9-3), preferably 7:3, and the two are woven into a flexible cloth, and then carbonized under an inert atmosphere to obtain a carbon cloth. The inert atmosphere is a gas atmosphere familiar to those skilled in the art, and nitrogen is preferred in the present invention. In some embodiments of the present invention, the flexible cloth is carbonized at 600-1200°C for 1-6h under an inert atmosphere to obtain a carbon cloth. The heating rate of the carbonization treatment cannot be too high, otherwise the fiber or the severe deformation during the carbonization due to excessively rapid heating causes the fiber to break or shrink, and the hollow morphology cannot be maintained. In some embodiments of the present invention, the carbonization treatment is heated to the target temperature at a rate lower than 2°C / min, preferably lower than 1°C / min.

[0042] The surface morphology of the obtained carbon cloth was characterized by scanning electron microscopy, and it was found that the carbon cloth woven with tree cotton fiber and cotton showed a molding morphology in which the fibers were entangled with each other, and the carbon fiber morphology prepared after carbonization treatment still had the hollow morphology of tree cotton fiber and cotton fiber. The fiber diameter was about 15μm and the carbon wall thickness was about 600nm.

[0043] After obtaining the carbon cloth, the carbon cloth is first etched to increase the surface roughness of the carbon cloth, which is convenient for the subsequent loading of graphene oxide. In some embodiments of the present invention, the etching treatment is specifically: the carbon cloth is washed with nitric acid, ethanol, and deionized water in sequence, wherein nitric acid can achieve a slight etching effect on the carbon cloth. In the present invention, other reagents can also be used to achieve the purpose of etching, such as hydrofluoric acid or hydrogen peroxide.

[0044] Then, the etched carbon cloth is mixed with a graphene oxide dispersion and ultrasonically treated to obtain a carbon cloth loaded with graphene oxide. In some embodiments of the present invention, the graphene oxide dispersion is a dispersion of graphene oxide in water, with an average radial size of 3 to 8 μm and a concentration of 2 to 10 mg / mL, and the ratio of the carbon cloth to the graphene oxide dispersion is 1 g: (5 to 50) mL. In some embodiments of the present invention, the mixed solution of the carbon cloth and the graphene oxide dispersion is ultrasonically treated at 35 to 50 KHz for 10 to 30 minutes, thereby introducing graphene oxide into the interior of the carbon cloth to obtain a carbon cloth loaded with graphene oxide.

[0045] Then, the carbon cloth loaded with graphene oxide is mixed with a reducing agent / graphene oxide dispersion and subjected to a temperature treatment to obtain the highly conductive and flexible rGO@carbon cloth. In some embodiments of the present invention, the reducing agent / graphene oxide dispersion is dripped onto the carbon cloth loaded with graphene oxide, and then treated at 60 to 100°C for 1 to 10 hours to obtain a highly conductive and flexible rGO@carbon cloth. The reducing agent / graphene oxide dispersion is obtained by mixing a reducing agent and a graphene oxide dispersion, and each 1 mL of graphene oxide dispersion includes 10 to 100 mg of a reducing agent, and the reducing agent can be selected from any one or more of L-ascorbic acid, phenylhydrazine, hydrazine hydrate or hydroiodic acid. Based on the obtained carbon cloth, the ratio of the carbon cloth to the reducing agent / graphene oxide dispersion is 1 g: (5 to 20) mL. The present invention can further introduce graphene oxide to the surface of the carbon cloth by mixing the carbon cloth loaded with graphene oxide with a reducing agent / graphene oxide dispersion and then subjecting the mixture to a temperature treatment. At the same time, since the conductivity of graphene oxide is poor, the presence of the reducing agent can reduce the graphene oxide introduced to the surface and inside of the carbon cloth to graphene, thereby giving the final rGO@carbon cloth excellent conductivity.

[0046] The surface morphology of the obtained rGO@carbon cloth was characterized by scanning electron microscopy, and it was found that the carbon cloth surface was loaded with a graphene oxide layer. In addition, by artificially bending the obtained rGO@carbon cloth, it was found that the rGO@carbon cloth had excellent flexibility and no breakage.

[0047] The preparation method of the highly conductive flexible rGO@carbon cloth provided by the present invention is simple and convenient. The flexible cloth woven from biomass fibers is carbonized and then compounded with graphene oxide and reduced to obtain the cloth. The raw material cost is low, and the carbon cloth molding method is simple, which is convenient for industrialization or industrial production.

[0048] The present invention also provides an electromagnetic shielding material, comprising the above-mentioned highly conductive flexible rGO@carbon cloth. According to research, the highly conductive flexible rGO@carbon cloth has excellent electromagnetic shielding effect, and the electromagnetic shielding efficiency can reach 22dB, and can show excellent properties in the fields of electromagnetic shielding or electrode materials.

[0049] In order to further illustrate the present invention, the following examples are used for detailed description. The experimental raw materials used in the following examples of the present invention can be purchased from the market or prepared according to conventional preparation methods well known to those skilled in the art. Among them, tree cotton fiber was purchased from Hainan Magic Tree Cotton Technology Co., Ltd., and the model was the third generation of Chinese tree cotton fiber; cotton fiber was ordinary absorbent cotton, which is generally commercially available; graphene oxide dispersion was purchased from Gaoxin Technology Co., Ltd., and the concentration was 10 mg / mL.

[0050] Example 1

[0051] This embodiment provides a highly conductive and flexible rGO@carbon cloth, and the preparation method thereof is as follows:

[0052] (1) Woven biomass fiber cloth:

[0053] Tree cotton fiber and cotton fiber (7 g of tree cotton fiber and 3 g of cotton fiber) with a mass ratio of 7:3 were used as raw materials for twisting, and woven into 10*20 mm fiber cloth after weaving;

[0054] (2) Preparation of carbon cloth:

[0055] The fiber cloth woven in step (1) is slowly heated to 1000° C. at a heating rate of less than 1 / min under a nitrogen atmosphere (gas purity ≥ 99.99%), and then carbonized for 2 h to obtain a carbon cloth material;

[0056] (3) Loading graphene oxide:

[0057] 0.2 g of the carbon cloth obtained in step (2) was washed with 20 mL of nitric acid, 20 mL of anhydrous ethanol and 50 mL of deionized water in sequence, and then immersed in 10 mL of 5 mg / mL graphene oxide aqueous dispersion for ultrasonic treatment (frequency 40 KHz, time 30 min);

[0058] The 5 mg / mL graphene oxide aqueous dispersion is obtained by diluting 10 mg / mL graphene oxide dispersion with water;

[0059] (4) Reduction of graphene oxide:

[0060] 50 mg of L-ascorbic acid was added to 1 mL of 5 mg / mL graphene oxide dispersion to obtain a reducing agent / graphene oxide mixed dispersion, which was drop-coated on the graphene oxide-loaded carbon cloth treated in step (3), and then heated to 90° C. and post-treated for 3 h to obtain a highly conductive and flexible rGO@carbon cloth.

[0061] The SEM images of the carbon cloth obtained in step (2) at different magnifications are as follows: Figure 1 , Figure 2 As shown by Figure 1 It can be seen that the carbon cloth woven with tree cotton fiber and cotton presents a morphology in which the fibers are intertwined. Figure 2 It can be seen that the carbon fiber morphology prepared after carbonization treatment still has the hollow morphology of tree cotton, wherein the fiber diameter is about 15 μm and the carbon wall thickness is about 600 nm.

[0062] The SEM image of the highly conductive and flexible rGO@carbon cloth finally prepared is shown in Figure 3 As shown, it can be seen that the surface and interior of the carbon cloth are loaded with graphene oxide layers.

[0063] The obtained highly conductive and flexible rGO@carbon cloth was bent, and the bending macroscopic diagram is shown in the figure. Figure 4 As shown, it is shown that the rGO@carbon cloth prepared by the present invention has excellent flexibility.

[0064] Example 2

[0065] This embodiment provides a highly conductive and flexible rGO@carbon cloth, and the preparation method thereof is as follows:

[0066] (1) Woven biomass fiber cloth:

[0067] Tree cotton fiber (9 g) and cotton fiber (1 g) with a mass ratio of 9:1 were used as raw materials for twisting, and woven into a 10*20 mm fiber cloth after weaving;

[0068] (2) Preparation of carbon cloth:

[0069] The fiber cloth woven in step (1) is slowly heated to 800° C. at a heating rate of less than 1 / min under a nitrogen atmosphere (gas purity ≥ 99.99%), and then carbonized for 2 h to obtain a carbon cloth material;

[0070] (3) Loading graphene oxide:

[0071] The 0.2 g carbon cloth obtained in step (2) was washed with 20 mL of nitric acid, 20 mL of anhydrous ethanol and 50 mL of water, and then immersed in 10 mL of 5 mg / mL graphene oxide aqueous dispersion for ultrasonic treatment (frequency 40 KHz, time 35 min);

[0072] The 5 mg / mL graphene oxide aqueous dispersion is obtained by diluting 10 mg / mL graphene oxide dispersion with water;

[0073] (4) Reduction of graphene oxide:

[0074] 50 mg of L-ascorbic acid was added to 1 mL of 5 mg / mL graphene oxide dispersion to obtain a reducing agent / graphene oxide mixed dispersion, which was drop-coated on the graphene oxide-loaded carbon cloth treated in step (3), then heated to 90° C. for post-treatment for 3 h, and then vacuum dried to obtain a highly conductive and flexible rGO@carbon cloth.

[0075] Comparative Example 1

[0076] This comparative example provides a flexible carbon cloth, and the preparation method thereof is as follows:

[0077] (1) Woven biomass fiber cloth:

[0078] Tree cotton fiber (7g) and cotton fiber (3g) with a mass ratio of 7:3 were used as raw materials for twisting, and woven into a 10*20mm fiber cloth after weaving;

[0079] (2) Preparation of carbon cloth:

[0080] The fiber cloth woven in step (1) is slowly heated to 800° C. at a heating rate of less than 1 / min under a nitrogen atmosphere (gas purity ≥ 99.99%), and then carbonized for 2 hours to obtain a flexible carbon cloth.

[0081] Performance Testing

[0082] The electromagnetic shielding performance of the carbon cloth finally prepared in Example 1 and Comparative Example 1 was tested, and the testing method was carried out with reference to the GJB 6190-2008 method.

[0083] Test results such as Figure 5 and Figure 6 As shown, SER is the reflection shielding effectiveness, SEA is the absorption shielding effectiveness, and SET is the electromagnetic shielding effectiveness, which is the sum of SER and SEA. It can be seen that the rGO@carbon cloth provided by the present invention has good electromagnetic shielding effectiveness (SET can reach 22dB), while the carbon cloth without loaded reduced graphene oxide has a SET of only about 13dB, which basically has no electromagnetic shielding effectiveness.

[0084] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A highly conductive and flexible rGO@carbon cloth, characterized in that: It consists of a carbon cloth and reduced graphene oxide supported on the carbon cloth; The carbon cloth is composed of woven biomass carbon fibers, and the biomass carbon fibers have a hollow structure; the carbon cloth is obtained by weaving biomass fibers and then carbonizing them; the carbonization treatment is specifically: heating to 600-1200°C at a rate lower than 2°C / min and then keeping the temperature for 1-6 hours; The biomass carbon fiber includes tree cotton carbon fiber and cotton carbon fiber; The mass ratio of the tree cotton carbon fiber to the cotton carbon fiber is (1-7):(9-3); The method for preparing the highly conductive and flexible rGO@carbon cloth comprises the following steps: (1) Provide carbon cloth; (2) etching the carbon cloth, mixing it with a graphene oxide dispersion and ultrasonicating it to obtain a carbon cloth loaded with graphene oxide; (3) The graphene oxide loaded carbon cloth is mixed with a reducing agent / graphene oxide dispersion and subjected to a temperature treatment to obtain the highly conductive and flexible rGO@carbon cloth.

2. The highly conductive and flexible rGO@carbon cloth according to claim 1, characterized in that: The mass ratio of the carbon cloth to the reduced graphene oxide is 1 g:(1-8) mg.

3. A method for preparing highly conductive and flexible rGO@carbon cloth, characterized in that: The following steps are involved: (1) Provide carbon cloth; The carbon cloth is obtained by weaving biomass fibers and then carbonizing them; the biomass fibers include tree cotton fibers and cotton fibers in a mass ratio of (1-7):(9-3); the carbonization treatment is specifically: heating to 600-1200°C at a rate lower than 2°C / min and then keeping the temperature for 1-6 hours; (2) etching the carbon cloth, mixing it with a graphene oxide dispersion and ultrasonicating it to obtain a carbon cloth loaded with graphene oxide; (3) The graphene oxide loaded carbon cloth is mixed with a reducing agent / graphene oxide dispersion and subjected to a temperature treatment to obtain the highly conductive and flexible rGO@carbon cloth.

4. The preparation method according to claim 3, characterized in that: The solvent of the graphene oxide dispersion is water, and the concentration is 2-10 mg / mL; In step (2), the ratio of the carbon cloth to the graphene oxide dispersion is 1 g: (5-50) mL.

5. The preparation method according to claim 4, characterized in that: The reducing agent / graphene oxide dispersion is obtained by mixing a reducing agent and a graphene oxide dispersion; The reducing agent is selected from any one or more of L-ascorbic acid, phenylhydrazine, hydrazine hydrate or hydroiodic acid; The ratio of the reducing agent to the graphene oxide dispersion is (10-100) mg:1 mL; In step (3), the ratio of the carbon cloth to the reducing agent / graphene oxide dispersion is 1 g:(5-20) mL.

6. The preparation method according to claim 3, characterized in that: The temperature of the heating treatment is 60-100°C and the time is 1-10 h.

7. An electromagnetic shielding material, characterized in that: It comprises the highly conductive and flexible rGO@carbon cloth according to claim 1 or 2, or the highly conductive and flexible rGO@carbon cloth prepared by the preparation method according to any one of claims 3 to 6.

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