A graphene / MXene composite film and preparation method thereof

Abstract

This invention discloses a graphene / MXene composite film and its preparation method. The preparation method includes: preparing an aqueous solution of MXene, an aqueous solution of graphene oxide, and a dispersion of polystyrene nanospheres; mixing the aqueous solution of MXene, the aqueous solution of graphene oxide, and the dispersion of polystyrene nanospheres, and ultrasonically dispersing them to obtain a mixed solution; vacuum filtering the mixed solution and coating it onto the surface of a film to obtain a composite film; and calcining the composite film under an inert atmosphere to obtain the graphene / MXene composite film. The preparation method provided by this invention is simple, the reaction conditions are mild, and it is easy to scale up production. The prepared graphene / MXene composite film has a multi-level mesoporous structure, which reduces the aggregation of graphene and MXene, thus exhibiting good capacitance performance. Furthermore, the graphene / MXene composite film has good bending flexibility and is expected to be directly used as an electrode material for flexible supercapacitors.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials, and in particular to a graphene / MXene composite film and a preparation method thereof. Background Art

[0002] In recent years, graphene and MXene have attracted widespread attention due to their unique lamellar structure and excellent physical and chemical properties. Graphene has low density, is easy to prepare, has excellent thermal and chemical stability, and the morphology of graphene assemblies is diverse and easy to composite with other materials. MXene is a two-dimensional nanomaterial with the advantages of good hydrophilicity, adjustable conductivity and rich surface functional groups. Composite membrane materials based on the two are expected to be used in electromagnetic shielding, coatings, piezoresistive sensors, capacitive deionized water purification and other fields.

[0003] The prior art discloses a variety of methods for preparing graphene oxide and MXene composite membranes, but most of them are to load the two two-dimensional materials onto the surface of a microfiltration membrane through vacuum filtration. However, graphene and MXene are prone to aggregation, and the combination of the two is not stable and is easy to fall off during use. Summary of the invention

[0004] In view of this, the present invention provides a graphene / MXene composite film and a preparation method thereof to solve the problem of poor performance of existing graphene / MXene composite films.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A method for preparing a graphene / MXene composite film comprises the following steps:

[0007] S1, preparing MXene aqueous solution, graphene oxide aqueous solution and polystyrene nanosphere dispersion;

[0008] S2, mixing the MXene aqueous solution, the graphene oxide aqueous solution and the polystyrene nanosphere dispersion, ultrasonically dispersing to obtain a mixed solution, and covering the mixed solution on the surface of the film by vacuum filtration to obtain a composite film;

[0009] S3. calcining the composite film under an inert atmosphere to obtain a graphene / MXene composite film.

[0010] Optionally, in step S1, the concentration of the MXene aqueous solution is in the range of 2 mg / mL to 4 mg / mL, the concentration of the graphene oxide aqueous solution is in the range of 2 mg / mL to 6 mg / mL, and the concentration of the polystyrene nanosphere dispersion is in the range of 10 mg / mL to 20 mg / mL.

[0011] Optionally, in the polystyrene nanosphere dispersion, the diameter of the polystyrene nanospheres is in the range of 100 nm to 300 nm.

[0012] Optionally, in the mixed solution of step S2, the mass ratio of MXene, graphene oxide and polystyrene nanospheres is (3-6): (5-10): (1-2).

[0013] Optionally, in step S2, the ultrasonic dispersion time is in the range of 10 min to 30 min.

[0014] Optionally, in step S3, the calcination temperature is in the range of 500°C to 600°C, and the calcination time is in the range of 2h to 4h.

[0015] Optionally, the material of the film includes one of polysulfone, polyethersulfone, polyvinylidene fluoride, cellulose acetate and mixed cellulose ester.

[0016] Based on the above scheme, the second purpose of the present invention is to provide a graphene / MXene composite film, which is prepared by the above-mentioned method for preparing the graphene / MXene composite film.

[0017] Optionally, the graphene / MXene composite film has a multi-level mesoporous structure.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] The preparation method provided by the present invention is simple, the reaction conditions are mild, and it is easy to scale up production. The prepared graphene / MXene composite film has a multi-level mesoporous structure, which weakens the aggregation of graphene and MXene, thereby having good capacitance performance. The graphene / MXene composite film has good bending flexibility and is expected to be directly used as an electrode material for flexible supercapacitors. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 This is a scanning electron microscope image of the graphene / MXene composite film described in Example 1 of the present invention. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0023] It should be noted that in the description of the embodiments of the present application, the description of the term "some specific embodiments" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same implementation or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0024] The “in the range of” described in this embodiment includes both end values, such as “in the range of 1 to 100” includes both end values ​​of 1 and 100.

[0025] MXene(Ti3C2T x ) is a new type of two-dimensional transition metal carbide or carbonitride, which is generally prepared by selectively removing the A atomic layer in the MAX phase (Ti3AlC2) by chemical etching and other methods. The chemical formula of MXene can be expressed as M n+1 X n T x (Where M is an early transition metal element, X represents carbon or nitrogen, and T is an active group attached to the surface). MXene has a high specific surface area, and its interlayer spacing and composition are adjustable and controllable. The rich surface hydrophilic functional groups such as -OH and -O enable it to be well dispersed in aqueous solution. The nanocomposite membrane constructed with MXene as the matrix and graphene oxide has strong plasticity and flexibility. However, graphene and MXene are prone to aggregation, and the combination of the two is not stable. Therefore, how to construct a composite membrane with stable structure and good electrochemical performance is currently a very valuable topic.

[0026] To solve the above problems, an embodiment of the present invention provides a method for preparing a graphene / MXene composite film, comprising the following steps:

[0027] S1, preparing MXene aqueous solution, graphene oxide aqueous solution and polystyrene nanosphere dispersion;

[0028] S2, mixing the MXene aqueous solution, the graphene oxide aqueous solution and the polystyrene nanosphere dispersion, ultrasonically dispersing to obtain a mixed solution, and covering the mixed solution on the surface of the film by vacuum filtration to obtain a composite film;

[0029] S3. calcining the composite film under an inert atmosphere to obtain a graphene / MXene composite film.

[0030] Specifically, in step S1, commercial MXene, graphene oxide and polystyrene nanospheres are dispersed in deionized water to prepare a 2-4 mg / mL MXene aqueous solution, a 2-6 mg / mL graphene oxide aqueous solution, and a 10-20 mg / mL polystyrene nanosphere aqueous dispersion. Of course, the above substances can also be homemade, and no specific restrictions are made here.

[0031] Preferably, the diameter of the polystyrene nanospheres is in the range of 100 nm to 300 nm.

[0032] Specifically, in step S2, MXene, graphene oxide, and polystyrene nanospheres are mixed in a mass ratio of (3-6): (5-10): (1-2), and after magnetic stirring, they are placed in an ultrasonic cleaner for dispersion for 10-30 minutes to obtain a mixed solution.

[0033] Fix the film on the vacuum filtration device, pour the mixed dispersion into the vacuum filtration cup, turn on the vacuum pump, and continue filtering for 30-40 minutes after the water is completely filtered out to obtain a composite film.

[0034] The material of the film includes one of polysulfone, polyethersulfone, polyvinylidene fluoride, cellulose acetate and mixed cellulose ester.

[0035] Specifically, in step S3, the composite membrane is placed in a tubular furnace and calcined at 500-600° C. for 2-4 hours.

[0036] Furthermore, the inert atmosphere includes argon or nitrogen, preferably argon atmosphere.

[0037] Therefore, in the embodiment of the present invention, graphene oxide, MXene, and polystyrene nanospheres are first mixed uniformly in water, and then filtered to obtain a composite film, and then calcined at high temperature to obtain a graphene / MXene composite film. The preparation process is simple and does not require complex reaction conditions and equipment. During the filtration process, the polystyrene nanospheres participate in the formation of the composite film, and then the polystyrene nanospheres are derived into carbon during high-temperature calcination, so that the composite film has a multi-level mesoporous structure, which weakens the aggregation of graphene and MXene; in addition, in the composite film, the synergistic effect of graphene, MXene, and polystyrene-derived carbon improves the capacitance performance of the composite film, and the graphene / MXene composite film has good bending flexibility, and is expected to be directly used as an electrode material for flexible supercapacitors.

[0038] Based on the above scheme, another embodiment of the present invention provides a graphene / MXene composite film, which is prepared by the above-mentioned method for preparing the graphene / MXene composite film.

[0039] On the basis of the above-mentioned embodiments, the present invention provides the following specific examples to further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. The experimental methods without specifying specific conditions in the following examples are usually based on the conditions recommended by the manufacturer. Unless otherwise stated, percentages and parts are calculated by mass.

[0040] Example 1

[0041] This embodiment provides a method for preparing a graphene / MXene composite film, comprising the following steps:

[0042] 1) MXene was prepared into an aqueous solution with a concentration of 2 mg / mL, graphene oxide was prepared into an aqueous solution with a concentration of 4 mg / mL, and polystyrene nanospheres with a diameter of 100 nm were prepared into an aqueous dispersion with a concentration of 10 mg / mL;

[0043] 2) Mixing a MXene solution, a graphene oxide solution, and a polystyrene nanosphere aqueous dispersion, and ultrasonicating for 15 minutes, wherein the mass ratio of MXene, graphene oxide, and polystyrene nanospheres is 3:6:2, and filtering on a polyvinylidene fluoride filter membrane to obtain a composite membrane;

[0044] 3) The composite film was calcined at 500°C in an argon atmosphere for 3 h to obtain a graphene / MXene composite film.

[0045] The graphene / MXene composite film prepared in Example 1 was characterized to obtain the following Figure 1 The scanning electron microscope image shown is from Figure 1 It can be seen that the graphene / MXene composite film has a layered multi-level structure.

[0046] The graphene / MXene composite film obtained in Example 1 was directly used as the working electrode, the silver / silver chloride electrode was used as the reference electrode, the platinum wire was used as the counter electrode, and 1 mol / L sulfuric acid was used as the supporting electrolyte. The charge and discharge test was performed at a current density of 1A / g. The specific capacitance of the graphene / MXene composite film was measured to be 562F / g; after bending 100 times, the specific capacitance of the composite film was measured again to be 534F / g. It can be seen that the specific capacitance does not change much after bending 100 times, that is, the graphene / MXene composite film has good specific capacitance performance and can be used as a flexible supercapacitor electrode material.

[0047] Example 2

[0048] This embodiment provides a method for preparing a graphene / MXene composite film, comprising the following steps:

[0049] 1) MXene was prepared into an aqueous solution with a concentration of 3 mg / mL, graphene oxide was prepared into an aqueous solution with a concentration of 4 mg / mL, and polystyrene nanospheres with a diameter of 200 nm were prepared into an aqueous dispersion with a concentration of 15 mg / mL;

[0050] 2) Mixing a MXene solution, a graphene oxide solution, and a polystyrene nanosphere aqueous dispersion, and ultrasonicating for 10 minutes, wherein the mass ratio of MXene, graphene oxide, and polystyrene nanospheres is 3:6:1, and filtering on a polysulfone filter membrane to obtain a composite membrane;

[0051] 3) The composite film was calcined at 550°C in an argon atmosphere for 2.5 h to obtain a graphene / MXene composite film.

[0052] The graphene / MXene composite film prepared in Example 2 was directly used as the working electrode, the silver / silver chloride electrode was used as the reference electrode, the platinum wire was used as the counter electrode, and 1 mol / L sulfuric acid was used as the supporting electrolyte. The charge and discharge test was performed at a current density of 1 A / g. The specific capacitance of the composite film was measured to be 504 F / g; after bending 100 times, the specific capacitance of the composite film was measured again to be 473 F / g.

[0053] Example 3

[0054] This embodiment provides a method for preparing a graphene / MXene composite film, comprising the following steps:

[0055] 1) MXene was prepared into an aqueous solution with a concentration of 4 mg / mL, graphene oxide was prepared into an aqueous solution with a concentration of 2 mg / mL, and polystyrene nanospheres with a diameter of 300 nm were prepared into an aqueous dispersion with a concentration of 20 mg / mL;

[0056] 2) Mixing a MXene solution, a graphene oxide solution, and a polystyrene nanosphere aqueous dispersion, and ultrasonicating for 10 minutes, wherein the mass ratio of MXene, graphene oxide, and polystyrene nanospheres is 2:8:2, and filtering on a polyethersulfone filter membrane to obtain a composite membrane;

[0057] 3) The composite film was calcined at 600°C in an argon atmosphere for 2 h to obtain a graphene / MXene composite film.

[0058] The graphene / MXene composite film prepared in Example 3 was directly used as the working electrode, the silver / silver chloride electrode was used as the reference electrode, the platinum wire was used as the counter electrode, and 1 mol / L sulfuric acid was used as the supporting electrolyte. The charge and discharge test was performed at a current density of 1 A / g. The specific capacitance of the composite film was measured to be 513 F / g; after bending 100 times, the specific capacitance of the composite film was measured again to be 464 F / g.

[0059] Example 4

[0060] This embodiment provides a method for preparing a graphene / MXene composite film, comprising the following steps:

[0061] 1) MXene was prepared into an aqueous solution with a concentration of 2 mg / mL, graphene oxide was prepared into an aqueous solution with a concentration of 6 mg / mL, and polystyrene nanospheres with a diameter of 150 nm were prepared into an aqueous dispersion with a concentration of 15 mg / mL;

[0062] 2) Mixing a MXene solution, a graphene oxide solution, and a polystyrene nanosphere aqueous dispersion, and ultrasonicating for 10 minutes, wherein the mass ratio of MXene, graphene oxide, and polystyrene nanospheres is 3:6:2, and filtering on a cellulose acetate filter membrane to obtain a composite membrane;

[0063] 3) The composite film was calcined at 500°C in an argon atmosphere for 2 h to obtain a graphene / MXene composite film.

[0064] The graphene / MXene composite film prepared in Example 4 was directly used as the working electrode, the silver / silver chloride electrode was used as the reference electrode, the platinum wire was used as the counter electrode, and 1 mol / L sulfuric acid was used as the supporting electrolyte. The charge and discharge test was performed at a current density of 1 A / g. The specific capacitance of the composite film was measured to be 453 F / g; after bending 100 times, the specific capacitance of the composite film was measured again to be 422 F / g.

[0065] Comparative Example 1

[0066] The comparative example provides a method for preparing a composite film, comprising the following steps:

[0067] 1) MXene was prepared into an aqueous solution with a concentration of 2 mg / mL, and graphene oxide was prepared into an aqueous solution with a concentration of 4 mg / mL;

[0068] 2) mixing a MXene solution and a graphene oxide solution, ultrasonicating for 15 minutes, wherein the mass ratio of MXene to graphene oxide is 3, and filtering on a polyvinylidene fluoride filter membrane to obtain a composite film;

[0069] 3) The composite film obtained in step 2) is calcined at 500° C. in an argon atmosphere for 3 h to obtain a graphene / MXene composite film.

[0070] The composite film prepared in Comparative Example 1 was directly used as the working electrode, the silver / silver chloride electrode was used as the reference electrode, the platinum wire was used as the counter electrode, and 1 mol / L sulfuric acid was used as the supporting electrolyte. The charge and discharge test was performed at a current density of 1 A / g. The specific capacitance of the composite film was measured to be 356 F / g; after bending 100 times, the specific capacitance of the composite film was measured again to be 312 F / g.

[0071] From the above embodiments, it can be seen that in the present invention, polystyrene nanospheres are added, and the polystyrene nanospheres participate in the formation of the composite film during the filtration process, and then the polystyrene nanospheres are derived into carbon during high-temperature calcination, so that the composite film has a multi-level mesoporous structure, and the synergistic effect of graphene, MXene, and polystyrene-derived carbon improves the capacitance performance of the composite film.

[0072] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A method for preparing a graphene / MXene composite film, characterized in that: The steps include: S1. Prepare a MXene aqueous solution, a graphene oxide aqueous solution and a polystyrene nanosphere dispersion, wherein the diameter of the polystyrene nanosphere is in the range of 100 nm to 300 nm, the concentration of the MXene aqueous solution is in the range of 2 mg / mL to 4 mg / mL, the concentration of the graphene oxide aqueous solution is in the range of 2 mg / mL to 6 mg / mL, and the concentration of the polystyrene nanosphere dispersion is in the range of 10 mg / mL to 20 mg / mL; S2, mixing the MXene aqueous solution, the graphene oxide aqueous solution and the polystyrene nanosphere dispersion, ultrasonically dispersing to obtain a mixed solution, and covering the mixed solution on the surface of the film by vacuum filtration to obtain a composite film, wherein the mass ratio of MXene, graphene oxide and polystyrene nanospheres is (3-6): (5-10): (1-2); S3. calcining the composite film under an inert atmosphere to obtain a graphene / MXene composite film, wherein the calcination temperature is in the range of 500° C. to 600° C., and the calcination time is in the range of 2 h to 4 h.

2. The preparation method according to claim 1, characterized in that: In step S2, the ultrasonic dispersion time is in the range of 10 min to 30 min.

3. The preparation method according to claim 1, characterized in that: The material of the film includes one of polysulfone, polyethersulfone, polyvinylidene fluoride, cellulose acetate and mixed cellulose ester.

4. A graphene / MXene composite film, characterized in that: The graphene / MXene composite film is prepared by the preparation method of any one of claims 1 to 3.

5. The graphene / MXene composite film according to claim 4, characterized in that: The graphene / MXene composite film has a multi-level mesoporous structure.

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