Method for preparing graphene titanium carbide crosslinked film material and application thereof in supercapacitors

Abstract

The present application relates to a method for preparing graphene titanium carbide crosslinked film material and its supercapacitor application. The film undergoes capillary shrinkage and weak interfacial interaction in the drying process, which makes the film orientation and density low, making it difficult to prepare graphene titanium carbide MXene film with high mechanical properties and high conductivity. Therefore, the present application uses the strategy of limiting a small amount of water molecules between graphene oxide and titanium carbide MXene nanosheet layers to realize the regular orientation of nanosheets. After reducing graphene oxide to graphene, the regular structure of graphene nanosheets is fixed by introducing π-π interaction between graphene layers, realizing the interfacial synergistic effect of covalent bond and π-π interaction between graphene and titanium carbide MXene. The tensile strength of the prepared graphene titanium carbide crosslinked composite film (ΠBMG) is as high as 1.63 GPa, and the conductivity is 1423 S cm ‑1 The film volume specific capacitance is as high as 1382 F cm ‑3 The volume energy density of the asymmetric supercapacitor prepared by using the film as a self-supporting negative electrode is as high as 47.62 mWh cm ‑3 .

Description

Technical Field

[0001] This invention relates to a method for preparing graphene-titanium carbide crosslinked thin film materials and their application in supercapacitors, belonging to the field of nanocomposite material preparation. Background Technology

[0002] The orientation, interfacial interactions, and packing density of nanosheets are key factors affecting the mechanical properties of two-dimensional nanomaterials. Ordered assembly ( Nat. Commun. 2018, 9 , 1.) Interfacial crosslinking ( Science 2021, 374 , 96.), pore filling ( Nat. Commun. 2020, 11 Strategies such as (2077.) have been used to improve the mechanical properties of two-dimensional nanomaterials and have achieved significant results. However, two-dimensional nanomaterials assembled by wet chemical methods inevitably undergo capillary shrinkage during the drying process as the solvent evaporates. Although capillary shrinkage helps to improve the density of the material, the accompanying severe structural shrinkage causes the nanosheets to have more wrinkles, which seriously affects the mechanical properties of the material.

[0003] Freeze-drying and supercritical drying can avoid capillary shrinkage of graphene and titanium carbide (MXene) during the drying process, but the resulting materials have a loose structure, low density, and poor mechanical properties. Researchers have reduced capillary shrinkage to some extent by increasing the contact angle between the nanosheets and the liquid and by solvent displacement. Although they have prepared self-supporting materials, they still cannot simultaneously achieve highly oriented and tightly packed two-dimensional nanosheets (S0). cience 2013, 341 , 534.). In recent years, external force traction strategies have been widely used to eliminate wrinkles and defects in graphene nanomaterials ( ). Nat. Mater. 2021, 20 ,624.). Intercalation, plasticizing, and stretching of GO films prepared by blade coating have been proven to effectively eliminate wrinkles in GO nanosheets. Nat. Commun. 2020, 11 , 1.). External stretching can eliminate wrinkles in graphene nanosheets, while interfacial cross-linking strategies can fix the ordered orientation structure of the nanosheets, achieving close packing of the nanosheets. Nat. Mater. 2021, 20 (624.). However, external force traction strategies are often complex processes, and achieving highly ordered orientation of graphene nanosheets during assembly remains a significant challenge.

[0004] Related studies have shown that interlayer water in graphene hydrogels can maintain the orderly stacking of graphene nanosheets and prevent their aggregation. This is mainly because the surface of graphene nanosheets contains negatively charged hydrophilic functional groups. In the presence of interlayer water, electrostatic repulsion and hydration can separate the graphene nanosheets from each other, thereby maintaining an orderly stacking state. Adv. Mater. 2011, 23 Based on this, by reducing the capillary shrinkage of the film during the drying process, the high orientation of the nanosheets can be maintained, ensuring that the film has a high degree of orientation and density.

[0005] Currently, relevant patents concerning graphene / titanium carbide (MXene) composite thin film materials include: a method for preparing a self-powered electronic skin system based on laser-reduced graphene / MXene composite material (CN 111759315 A), a method for preparing a dense structure RGO / MXene-sulfuric acid supercapacitor flexible electrode in one step and its application (CN110993375B), a method for preparing a graphene / MXene composite thin film (CN114914100A), a method for preparing an oxidized cellulose-graphene nanoribbon-MXene composite conductive thin film (CN111883314A), and a porous graphene / Ti3C2T composite film for an ultrafast electrochemical capacitor. x Preparation methods and applications of composite thin film materials (CN114655950A), and a preparation method and application of titanium carbide / MXene-functionalized graphene nanocomposite thin films (CN111252768B). Papers on graphene / titanium carbide / MXene composite thin film materials include: a) Adv. Funct. Mater. 2017, 27 , 1701264.;b) Nat. Commun. 2020, 11 , 2077.;c) Adv. Sci. 2018, 5 The above patents and papers only discuss the applications of graphene / titanium carbide MXene composite films in terms of mechanical or electrical properties, and do not mention the problem of reduced film orientation and density caused by capillary shrinkage. Summary of the Invention

[0006] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a method for preparing graphene-titanium carbide crosslinked thin film materials and their application in supercapacitors. This method can successfully prepare graphene-titanium carbide (MXene) crosslinked composite thin film materials with high orientation, high strength, high modulus, high conductivity, and high density.

[0007] This invention provides a method for preparing highly oriented, dense graphene-titanium carbide-MXene crosslinked composite thin films (ΠBMG) using a continuous vacuum filtration technique. This method involves forming covalent bonds between titanium carbide (MXene) and graphene oxide (GO) during film preparation. The method effectively suppresses capillary shrinkage by confining water between nanosheets during the film preparation process, inducing high orientation of the nanosheets. Efficient stress transfer is achieved through the synergistic effect of covalent bonds and π-π interactions at the interface. The resulting ΠBMG material exhibits a tensile strength of 855.42-1628.39 MPa, a Young's modulus of 17.49-85.96 GPa, and an electrical conductivity of 1297.76-1423.04 S cm⁻¹. -1 The improvement in tensile strength and electrical conductivity is mainly due to the interfacial synergistic effect of the Ti-OC covalent bonds between titanium carbide MXene nanosheets and graphene nanosheets, as well as the effective suppression of capillary shrinkage during the preparation process, ensuring a highly oriented and dense structure of the film. Furthermore, wide-angle X-ray scattering (WLS) confirmed that suppressing capillary shrinkage effectively improves the film's orientation. Porosity calculations and scanning electron microscopy (SEM) structural characterization of the film's cross-section also confirmed that suppressing capillary shrinkage effectively improves the film's density.

[0008] In this invention, the orientation degree is represented by the Herman orientation factor.

[0009] This invention is achieved through the following technical solution: First, a high-quality monolayer large-scale titanium carbide MXene nanosheet (with a sheet diameter of 5-30 micrometers) aqueous dispersion is obtained by chemical etching and oscillatory exfoliation. Then, a large-scale monolayer graphene oxide (GO) nanosheet aqueous dispersion (with a sheet diameter of 5-30 micrometers) is prepared using a modified Hummers method. Second, titanium carbide MXene and graphene oxide (GO) nanosheets of different mass ratios are assembled into a hydrogel film using vacuum filtration, casting, blade coating, or centrifugal casting. Third, water molecules are confined by continuous vacuum filtration. By suppressing capillary shrinkage of the film during the drying process between nanosheet layers, highly oriented (Herman orientation factor of 0.830-0.901, preferably 0.830-0.870) and dense (porosity of 5.36%-18.71%) graphene oxide (GO) titanium carbide MXene film (MGO) is obtained. Finally, the graphene oxide (GO) titanium carbide MXene film (MGO) is reduced and crosslinked to obtain a highly oriented, high-density graphene titanium carbide MXene crosslinked composite film (ΠBMG) material.

[0010] The present invention provides a method for preparing a graphene-titanium carbide crosslinked thin film material, comprising the following steps:

[0011] (1) The raw material MAX phase is chemically etched with lithium fluoride (LiF) and hydrochloric acid (HCl), and reacted under heating conditions (reaction temperature 35-50℃, reaction time 24-30 h). After washing, shaking and peeling and gradient centrifugation, a single-layer MXene nanosheet (sheet diameter 5-30 μm) aqueous dispersion is prepared; preferably, the MAX phase is Ti3AlC2; preferably, the MXene is Ti3C2T x ;

[0012] (2) The raw graphite powder is reacted with concentrated sulfuric acid (H2SO4) and potassium permanganate (KMnO4) with a mass fraction of 98 wt% at low temperature, and then washed and separated by gradient centrifugation to prepare a single-layer graphene oxide (GO) nanosheet (sheet diameter of 5-30 micrometers) aqueous dispersion; preferably, the low temperature is -5℃~10℃;

[0013] (3) The aqueous dispersion of monolayer MXene nanosheets (with a diameter of 5-30 micrometers) described in step (1) and the aqueous dispersion of monolayer graphene oxide (GO) nanosheets (with a diameter of 5-30 micrometers) described in step (2) are stirred to obtain a uniform dispersion of MXene nanosheets and graphene oxide (GO) nanosheets; preferably, the stirring reaction time is 0.5-2 h;

[0014] (4) The uniform dispersion of titanium carbide MXene nanosheets and graphene oxide (GO) nanosheets in step (3) is concentrated to obtain graphene oxide (GO) titanium carbide MXene hydrogel; preferably, the concentration method is vacuum filtration and gradient centrifugation;

[0015] (5) The graphene oxide (GO) titanium carbide MXene hydrogel obtained in step (4) is used to form a hydrogel membrane with a thickness of 50-3000 micrometers on a flexible porous substrate; preferably, the membrane forming process includes vacuum filtration, casting, scraping or centrifugal casting; preferably, the flexible porous substrate is a mixed cellulose ester filter membrane.

[0016] (6) The graphene oxide (GO) titanium carbide MXene hydrogel membrane obtained in step (5) is used to prepare a highly oriented graphene oxide (GO) titanium carbide MXene film (thickness of 0.5-20 micrometers) with limited water support (Herman orientation factor of 0.830-0.870) by continuously vacuum filtering for 0.5-5 days until the film exhibits a metallic luster; preferably, the porosity of the graphene oxide titanium carbide MXene film is 5.36%-18.71%;

[0017] (7) The graphene oxide (GO) titanium carbide MXene film (MGO) obtained in step (6) is reduced with a reducing agent to obtain a graphene titanium carbide MXene film (MG); preferably, the reducing agent is hydroiodic acid (HI).

[0018] (8) The graphene titanium carbide MXene film (MG) obtained in step (7) is washed with detergent and replaced with a displacement agent, and then immersed in a crosslinking agent solution to crosslink and produce graphene titanium carbide crosslinked film (BMG) material; preferably, the detergent is anhydrous ethanol, the displacement agent is N,N-dimethylformamide (DMF), and the crosslinking agent is a solution of N,N-dimethylformamide (DMF) of N-carboxysuccinimide ester (PSE) and a solution of N,N-dimethylformamide (DMF) of 1-aminopyrene (AP).

[0019] Further, in step (1), the preparation of a monolayer titanium carbide MXene nanosheet aqueous dispersion using oscillation exfoliation and gradient centrifugation is as follows: the accordion-shaped MXene phase is dispersed in water, oscillated under closed conditions for 2-15 min, and then subjected to gradient centrifugation to obtain the MXene nanosheet aqueous dispersion; in step (3), when the monolayer MXene nanosheet (sheet diameter 5-30 μm) aqueous dispersion and the monolayer graphene oxide (GO) nanosheet (sheet diameter 5-30 μm) aqueous dispersion are stirred and reacted, the mass ratio of MXene nanosheets to graphene oxide (GO) nanosheets is controlled between 1-50%; preferably, the mass ratio of MXene nanosheets to graphene oxide (GO) nanosheets is 1-20%, and by using this preferred ratio, high strength (855.42-1628.39 MPa) and high conductivity (1297.76-1423.04 S cm) can be prepared. -1 ) graphene titanium carbide MXene crosslinked composite film (ΠBMG) material.

[0020] Furthermore, in step (3), the stirring reaction time is 0.5-6 h; preferably, the stirring reaction time is 0.5-2 h, which allows the monolayer titanium carbide MXene nanosheets to react fully with the monolayer graphene (GO) nanosheets and carry out the chemical reaction.

[0021] Furthermore, in step (6), during the process of removing moisture from the graphene oxide (GO) titanium carbide MXene hydrogel membrane by continuous filtration, filtration is stopped only when the membrane exhibits a metallic luster; wherein the vacuum filtration time is preferably 0.5-5 days.

[0022] Furthermore, in step (8), the prepared graphene titanium carbide MXene crosslinked film (ΠBMG) material has a Herman orientation factor of 0.634-0.901 and a porosity of 5.36-32.68%.

[0023] Furthermore, in step (8), the graphene titanium carbide MXene film (MG) does not undergo a drying process during the cleaning, solvent replacement and crosslinking agent immersion process; wherein the preferred crosslinking agent immersion time is 10-48 h.

[0024] The present invention also provides an application of the graphene-titanium carbide crosslinked film (ΠBMG) material prepared by the method described above in supercapacitors.

[0025] Furthermore, the application includes: using the graphene-titanium carbide MXene cross-linked composite film (ΠBMG) material obtained in step (8) directly as a self-supporting electrode to test electrochemical performance.

[0026] The principle of this invention: This invention first uses high-quality monolayer titanium carbide (MXene) nanosheets (5-30 μm in diameter) and monolayer graphene oxide (GO) nanosheets (5-30 μm in diameter) as raw materials. These are reacted at room temperature with stirring to generate Ti-OC covalent bonds. A graphene oxide (GO) / titanium carbide (MXene) hydrogel film is then prepared using a vacuum filtration method. Next, continuous vacuum filtration introduces confined water between the nanosheet layers to effectively suppress capillary shrinkage of the hydrogel film, preparing a highly oriented graphene oxide (GO) / titanium carbide (MXene) film (MGO), effectively ensuring the film's porosity. Then, the prepared graphene oxide (GO) / titanium carbide (MXene) film (MGO) undergoes reduction and crosslinking treatment to prepare a highly oriented, high-density graphene oxide (GO) / titanium carbide (MXene) crosslinked composite film (ΠBMG) material.

[0027] Meanwhile, compared with existing methods for preparing graphene-titanium carbide (MXene) crosslinked composite thin film materials, the advantages of this invention are:

[0028] (1) High-quality titanium carbide MXene nanosheets and graphene oxide (GO) nanosheets form Ti-OC covalent bonds at room temperature. Water molecules are confined between the nanosheet layers by continuous vacuum filtration, which effectively suppresses capillary shrinkage during the film drying process and gives the film a highly oriented structure.

[0029] (2) Because the capillary shrinkage of graphene oxide (GO) titanium carbide (MGO) film during the drying process is effectively suppressed, the highly oriented structure is maintained, thus effectively reducing the porosity of the film.

[0030] (3) The synergistic effect of covalent bonds and π-π interactions at the interface enables effective stress transfer between nanosheets, resulting in excellent mechanical properties for the graphene-titanium carbide (MXene) crosslinked composite film (ΠBMG) material, including tensile strength of 855.42-1628.39 MPa, Young's modulus of 17.49-85.96 GPa, and electrical conductivity of 1297.76-1423.04 S cm⁻¹. -1 ;

[0031] (4) In addition, based on the graphene-titanium carbide MXene cross-linked composite film (ΠBMG) material, the present invention directly uses the film nanocomposite material as a supercapacitor electrode, assembles it into a supercapacitor, and applies it to the field of flexible electronics. Attached Figure Description

[0032] Figure 1 This invention relates to a method for preparing graphene-titanium carbide crosslinked composite thin film materials and its application in supercapacitors. First, graphene oxide (GO)-titanium carbide (MXene) hydrogel is subjected to continuous vacuum filtration to remove excess water until the film exhibits a metallic luster. Filtration is then stopped to prepare a highly oriented graphene oxide (GO)-titanium carbide (MXene) thin film (MGO). The highly oriented graphene oxide (GO)-titanium carbide (MXene) thin film (MGO) is reduced with hydroiodic acid (HI) and then π-π crosslinked with a crosslinking agent to prepare a graphene-titanium carbide (MXene) crosslinked composite thin film (ΠBMG) material.

[0033] Figure 2 This invention relates to a method for preparing graphene-titanium carbide crosslinked composite thin film materials and evidence of Ti-OC covalent bonding in their application in supercapacitors (Example 3): a, FTIR infrared spectrum; b, X-ray photoelectron spectroscopy (XPS) O1s spectrum of graphene oxide (GO) film; c, X-ray photoelectron spectroscopy (XPS) O1s spectrum of titanium carbide (MXene) film; d, X-ray photoelectron spectroscopy (XPS) O1s spectrum of highly oriented graphene oxide (GO) and titanium carbide (MXene) films.

[0034] Figure 3This invention relates to a method for preparing graphene-titanium carbide crosslinked composite thin film materials and evidence of improved film orientation and density in supercapacitor applications (Example 3): a, Wide-angle X-ray scattering spectrum of graphene oxide (GO)-titanium carbide (MXene) hydrogel film; b, Wide-angle X-ray scattering spectrum of capillary-dried graphene oxide (GO)-titanium carbide (MXene) film (CMGO); c, Wide-angle X-ray scattering spectrum of highly oriented graphene oxide (GO)-titanium carbide (MXene) film (MGO); d, Focused ion beam cross-sectional scanning electron microscope (FIB-SEM) image of pure reduced graphene oxide (rGO); e, Crosslinked graphene-titanium carbide (MXene) film. f. Focused ion beam scanning electron microscope (FIB-SEM) image of the cross-section of the composite film (ΠBMG); g. High-angle annular dark field (HAADF) image of the graphene-titanium carbide MXene cross-linked composite film (ΠBMG); h. Wide-angle X-ray scattering spectrum of the reduced graphene oxide (rGO) film; i. Wide-angle X-ray scattering spectrum of the graphene-titanium carbide MXene cross-linked composite film (ΠBMG); j. Comparison of tensile strength and porosity between the reduced graphene oxide (rGO) film and the graphene-titanium carbide MXene cross-linked composite film.

[0035] Figure 4 This invention relates to a method for preparing graphene-titanium carbide crosslinked composite film materials and their mechanical properties in supercapacitor applications (Example 3). a) Stress-strain curves of reduced graphene oxide (rGO) film and graphene-titanium carbide MXene crosslinked composite film (ΠBMG); b) Scanning electron microscope (SEM) image of the fracture surface of reduced graphene oxide (rGO) film and graphene-titanium carbide MXene crosslinked composite film (ΠBMG) after tensile fracture; c) In-situ Raman spectrum of reduced graphene oxide (rGO) film; d) In-situ Raman spectrum of graphene-titanium carbide MXene crosslinked composite film (ΠBMG); e) Stress relaxation curves of reduced graphene oxide (rGO) film and graphene-titanium carbide MXene crosslinked composite film (ΠBMG); f) Comparison of tensile strength-Young's modulus between graphene-titanium carbide MXene crosslinked composite film (ΠBMG) and graphene films prepared by different processes reported in the literature.

[0036] Figure 5 This invention relates to a method for preparing graphene-titanium carbide crosslinked composite thin film materials and their electrochemical performance in supercapacitor applications (Example 3). a) Graphene-titanium carbide MXene crosslinked composite thin film (ΠBMG) and capillary-shrinking graphene-titanium carbide MXene crosslinked composite thin film (CΠBMG) were subjected to a scan rate of 10 mV s.-1 a) Cyclic voltammetry curves; b) Rate characteristics curves of graphene-titanium carbide (MXene) crosslinked composite film (ΠBMG) and capillary-shrinkable graphene-titanium carbide (MXene) crosslinked composite film (CΠBMG) at different current densities; c) Peak current-scan rate relationship of graphene-titanium carbide (MXene) crosslinked composite film (ΠBMG) and capillary-shrinkable graphene-titanium carbide (MXene) crosslinked composite film (CΠBMG); d) Comparison of capacity contribution between graphene-titanium carbide (MXene) crosslinked composite film (ΠBMG) and capillary-shrinkable graphene-titanium carbide (MXene) crosslinked composite film (CΠBMG); e) Comparison of volumetric specific capacitance-mass specific capacitance between graphene-titanium carbide (MXene) crosslinked composite film (ΠBMG) and materials reported in the literature; f) Lagunta comparison of the asymmetric supercapacitor involved in this invention with supercapacitors reported in the literature; g) The asymmetric supercapacitor involved in this invention at 200 mV s -1 The cyclic stability curve is shown below. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. However, the following embodiments are only for explaining the present invention, and the scope of protection of the present invention should include all the contents of the claims. Moreover, through the description of the following embodiments, those skilled in the art can fully implement all the contents of the claims of the present invention.

[0038] The method of the present invention is implemented as follows: Figure 1 This invention relates to a method for preparing graphene-titanium carbide crosslinked composite thin film materials and its application in supercapacitors. First, graphene oxide (GO)-titanium carbide (MXene) hydrogel is subjected to continuous vacuum filtration to remove excess water until the film exhibits a metallic luster. Filtration is then stopped to prepare a highly oriented graphene oxide (GO)-titanium carbide (MXene) thin film (MGO). The highly oriented graphene oxide (GO)-titanium carbide (MXene) thin film (MGO) is reduced with hydroiodic acid (HI) and then π-π crosslinked with a crosslinking agent to prepare a graphene-titanium carbide (MXene) crosslinked composite thin film (ΠBMG) material.

[0039] The high-quality monolayer titanium carbide MXene nanosheets described in this invention are a two-dimensional layered material of alternating Ti / C titanium carbide. Their surface contains a large number of oxygen-containing functional groups, exhibiting good electrical conductivity and electrochemical activity. They can form Ti-OC covalent bonds with graphene oxide (GO) under room temperature stirring conditions. The graphene oxide (GO) is a two-dimensional nanosheet rich in oxygen-containing functional groups, which can form Ti-OC covalent bonds with the MXene nanosheets. The pyrene butyric acid N... N-Carboxysuccinimide ester (PSE) is a small organic molecule containing a pyrene group, which can form π-π interactions with graphene nanosheets; 1-Aminopyrene is a small organic molecule containing a pyrene group, which can form π-π interactions with graphene nanosheets; N-Carboxysuccinimide ester (PSE) and 1-Aminopyrene (AP) can react at room temperature to generate N-Carboxysuccinimide-1-Aminopyrene (PSE-AP).

[0040] The obtained graphene-titanium carbide MXene crosslinked composite film (ΠBMG) material has a thickness of 0.5-20 micrometers.

[0041] In the following embodiments of the present invention, the following testing methods are used:

[0042] A: The tensile strength test method includes the following steps: The prepared graphene-titanium carbide (MXene) cross-linked composite film is cut into test strips with a length of 1 cm and a width of 3 mm. The strips are fixed on a paper test template with a span of 0.5 cm. A Shimadzu AGS-X tensile tester equipped with a 100 N sensor is used to test the tensile properties of the test strips at a tensile speed of 0.5 mm / min, thus obtaining the stress-strain curve of the film. The tensile strength is calculated as: tensile force at break / cross-sectional area of ​​the test strip.

[0043] B: The porosity testing method includes the following steps: film porosity = 1 - film measured density / film theoretical density, where film measured density = film mass / film volume, and film theoretical density is calculated based on the content of each component in the composite film.

[0044] C: Young's modulus test method: Young's modulus is obtained by calculating the slope of the elastic region of the stress-strain curve.

[0045] Example 1

[0046] Add 24 mL of concentrated sulfuric acid (98 wt%) to a 150 mL three-necked flask and cool to below 5°C in an ice bath. Slowly add 1.0 g of graphite powder (325 mesh) (Qingdao Jinrilai Co., Ltd.), and magnetically stir at 500 rpm for 1.5 h below 5°C. Slowly add 3.0 g of KMnO4 over 2.0 h, always keeping the temperature below 5°C, and continue stirring for 10 h after the addition is complete. Add 50 mL of pre-frozen deionized water using a syringe pump, always keeping the temperature below 5°C for approximately 8.0 h, and continue stirring for 1 h after the addition is complete. Pour the reaction mixture into 600 mL of pre-frozen deionized water to terminate the reaction. Slowly add 20 mL of H2O2 (30%), stirring for 20 min. Place the mixture in a refrigerator to settle for 2 days (2-4°C). Centrifuge three times with dilute HCl (3.7 wt%) at 10000 rpm for 5 min at 2-4°C to remove Mn. 2+ Centrifuge four times at 10,000 rpm for 5 min with deionized water at 2-4℃ to remove excess acid. Centrifuge three times at 3,000 rpm for 10 min to collect the supernatant and separate unseparated particles. Centrifuge the supernatant at 10,000 rpm for 10 min to obtain the precipitate. Disperse the precipitate in deionized water at 2-4℃ to prepare 4 mg / mL solutions. -1 The dispersion is stored in a refrigerator (2-4℃) to obtain a large monolayer GO dispersion with a sheet diameter of 5-30 micrometers.

[0047] Example 2

[0048] Add 5 mL of deionized water to a 100 mL PTFE reagent bottle, add 15 mL of concentrated hydrochloric acid (36 wt%), and stir at 800 rpm for 5 min. Slowly add 1.6 g of LiF while stirring, and stir for 5 min. Slowly add 1.0 g of Ti3AlC2 (Jilin Yiyi Technology Co., Ltd.) while stirring, and stir for 5 min. Tighten the PTFE reagent bottle and seal the opening with sealing film. Turn on the water bath heating function, adjust the stirring speed to 800 rpm, and heat the water bath to 50°C. o C, react for 30 h. Turn off the heating, remove the PTFE reagent bottle from the water bath, and cool to room temperature. Open the PTFE reagent bottle in a fume hood, add water to the reaction product, and centrifuge at 3500 rpm for 5 min to pH 6. Shake for 5 min, then centrifuge at 1500 rpm for 30 min to collect the supernatant. Centrifuge at 4500 rpm for 20 min to collect the supernatant, take the precipitate, and disperse the precipitate in water to prepare a concentration of 2 mg / mL. -1The dispersion yields a large monolayer MXene dispersion with a sheet diameter of 5-30 micrometers. This dispersion is stored in a refrigerator at 2-4°C for later use.

[0049] Example 3

[0050] Take 10 mL of the GO dispersion prepared in Example 1 (4 mg / mL) -1 Place the solution in a 50 mL glass bottle, add 10 mL of deionized water, stir and disperse for 10 min, then take 5 mL of the MXene dispersion prepared in Example 2 (2 mg / mL). -1 Add the GO to the GO dispersion and stir for 1 h. Centrifuge the stirred dispersion at 10000 rpm for 10 min to obtain a GO-MXene composite hydrogel. Coat this hydrogel onto a mixed cellulose substrate to form a graphene oxide (GO)-titanium carbide (MXene) hydrogel film. Transfer the hydrogel film to a solvent filter and continuously vacuum filter for 0.5-5 days until the film exhibits a metallic luster, then stop filtration to obtain an MGO film with an MXene mass fraction of 18.6 wt%. Reduce the obtained MGO film with 38 wt% hydroiodic acid for 10 h, then wash with anhydrous ethanol and dry at room temperature for 12 h to obtain a graphene-titanium carbide (MXene) (MG) film. Place the MG film in a 48 mmol L... -1 The membrane was soaked in a PSE-DMF solution for 24 h, washed five times with DMF to remove PSE from the membrane surface, and then placed in a 48 mmol / L solution. -1 The graphene-titanium carbide (MXene) crosslinked composite film (ΠBMG) was obtained by immersing the film in an AP DMF solution for 24 h, washing it five times with DMF, and drying it at room temperature for 24 h. ΠBMG films with thicknesses ranging from 0.5 to 20 micrometers could be obtained by adjusting the coating height. The obtained ΠBMG films had a tensile strength of 1628.39 MPa, a Young's modulus of 85.96 GPa, and an electrical conductivity of 1423.04 S / cm. -1 .

[0051] Example 4

[0052] Take 1.2 mL of the GO dispersion prepared in Example 1 (4 mg / mL) -1 Place the sample in a 20 mL glass bottle, add 4.2 mL of deionized water, and stir to disperse for 10 min. Take 0.6 mL of the MXene dispersion prepared in Example 2 (2 mg / mL). -1Add the MXene to the GO dispersion and stir for 1 h. Transfer the stirred dispersion to a solvent filter and filter for 0.5-5 days until the film exhibits a metallic luster, then stop filtration to obtain the MGO film, in which the mass fraction of MXene is 18.6 wt%. Reduce the obtained MGO film with 37-38 wt% hydroiodic acid for 10 h, then wash with anhydrous ethanol and dry at room temperature for 12 h to obtain the MG film. Place the MG film in a 48 mmol L... -1 The membrane was soaked in a PSE-DMF solution for 24 h, washed five times with DMF to remove PSE from the membrane surface, and then placed in a 48 mmol / L solution. -1 The graphene titanium carbide (MXene) film (MG) and the graphene titanium carbide (MXene) crosslinked composite film (ΠBMG) were obtained by soaking the film in an AP DMF solution for 24 h, washing it five times with DMF, and drying it at room temperature for 24 h. The thickness of the obtained ΠBMG film was 0.5-0.8 μm. The tensile strength of the obtained ΠBMG film was 1470.87 MPa, and the Young's modulus was 65.53 GPa.

[0053] Example 5

[0054] Take 3.56, 3.38, 3, 2.63, and 1.88 mL of the GO dispersion prepared in Example 1 (4 mg / mL) respectively. -1 The sample was placed in a 20 mL glass bottle, and 11.06, 11.88, 10.50, 10.13, and 9.38 mL of deionized water were added respectively. The mixture was stirred and dispersed for 10 min. 0.38, 0.75, 1.50, 2.25, and 3.75 mL of the MXene dispersion (2 mg / mL) prepared in Example 2 were then taken respectively. -1 The GO dispersion was added and stirred for 1 h. The stirred dispersion was then transferred to a solvent filter and filtered for 4 h to obtain a hydrogel membrane. The hydrogel membrane was dried at room temperature to obtain a capillary-dried graphene oxide (CMGO) composite film, in which the mass fractions of MXene were 1.4 wt%, 12.7 wt%, 18.6 wt%, 23.4 wt%, and 44.4 wt%.

[0055] Example 6

[0056] Take 1.2 mL of the GO dispersion prepared in Example 1 (4 mg / mL) -1 The sample was placed in a 20 mL glass bottle, and 4.2 mL of deionized water was added. The mixture was stirred and dispersed for 10 min. 0.6 mL of the MXene dispersion (2 mg / mL) prepared in Example 2 was then taken. -1Add the GO dispersion and stir for 1 h. Transfer the stirred dispersion to a solvent filter and filter for 4 h to obtain a hydrogel membrane. Dry the hydrogel membrane at room temperature to obtain a capillary-dried graphene oxide-MXene composite film (CMGO), in which the mass fraction of MXene is 18.6 wt%. Reduce the obtained CMGO film with 37-38 wt% hydroiodic acid for 10 h, wash with anhydrous ethanol, and dry at room temperature for 12 h to obtain the MG film. Place the MG film in a 48 mmol L... -1 The membrane was soaked in a PSE-DMF solution for 24 h, washed five times with DMF to remove PSE from the membrane surface, and then placed in a 48 mmol / L solution. -1 The graphene-titanium carbide (CΠBMG) cross-linked composite film was obtained by immersing the film in an AP DMF solution for 24 h, washing it five times with DMF, and drying it at room temperature for 24 h. The thickness of the obtained CΠBMG film was 1.5 μm.

[0057] Example 7

[0058] Take 1.5 mL of the GO dispersion prepared in Example 1 (4 mg / mL) -1 The sample was placed in a 20 mL glass bottle, and 4.5 mL of deionized water was added. The mixture was stirred and dispersed for 10 min. The dispersion was transferred to a solvent filter and filtered for 12 h to obtain a hydrogel membrane. The hydrogel membrane was dried at room temperature to obtain a GO film. The obtained GO film was reduced with 38 wt% hydroiodic acid for 10 h, washed with anhydrous ethanol, and dried at room temperature for 12 h to obtain a reduced graphene oxide (rGO) film. The obtained rGO film had a thickness of 1.5 μm, a tensile strength of 307.75 MPa, a Young's modulus of 1.61 GPa, and an electrical conductivity of 898.16 S cm⁻¹. -1 The obtained rGO film was placed in 48 mmol L... -1 The membrane was soaked in a PSE-DMF solution for 24 h, washed five times with DMF to remove PSE from the membrane surface, and then placed in a 48 mmol / L solution. -1 The rGO film (π-π crosslinked) was obtained by soaking in AP DMF solution for 24 h, washing with DMF 5 times, and drying at room temperature for 24 h.

[0059] Example 8

[0060] The ΠBMG film prepared in Example 3 was cut into squares with a width of 3 mm and used as a self-supporting electrode. A glassy carbon electrode was used as the current collector, an activated carbon sheet as the counter electrode, and an Ag / AgCl electrode as the reference electrode. 3 mol L -1A three-electrode system was assembled using sulfuric acid aqueous solution as the electrolyte, and the electrochemical performance of the ΠBMG thin film was tested using a CHI 660E electrochemical workstation. The film exhibited a high volumetric specific capacity of 1382 F cm⁻¹. -3 It exhibits excellent electrochemical performance. Using the ΠBMG thin film as the negative electrode and the ΠBG thin film from Example 6 as the positive electrode, at a concentration of 3 mol L... -1 An asymmetric supercapacitor was assembled using sulfuric acid aqueous solution as the electrolyte, achieving a volumetric energy density of 47.62 mWh / cm³. -3 This is higher than most MXene-based self-supporting supercapacitors. At 200 mV s -1 After 40,000 cycles, the capacity retention rate was 100%, demonstrating excellent cycling stability.

[0061] Example 9

[0062] Based on the FTIR spectrum of the prepared fiber material ( Figure 2 As shown in a) of Example 3, the graphene oxide (GO) titanium carbide MXene film (MGO), graphene titanium carbide MXene film (MG), and graphene titanium carbide MXene crosslinked composite film (ΠBMG) prepared in Example 3 have a thickness of ~837 cm⁻¹. -1 A new peak is observed, indicating the formation of Ti-OC covalent bonds between titanium carbide MXene nanosheets and graphene oxide (GO) nanosheets. X-ray photoelectron spectroscopy (XPS) O 1s spectrum ( Figure 2 The results (bd) show that, compared to pure titanium carbide MXene and pure GO films, the MGO film exhibits a new peak at 530.4 eV, indicating the formation of Ti-OC covalent bonds between titanium carbide MXene nanosheets and graphene oxide (GO) nanosheets.

[0063] Example 10

[0064] The MGO film prepared by continuous vacuum filtration (Example 3) exhibited a significantly higher Herman orientation factor than the CMGO film that underwent capillary shrinkage (Example 6) due to suppressed capillary shrinkage. The orientation factor of the film material was characterized by wide-angle X-ray scattering (SWAXS Xenocs Nanoinxider analyzer). Figure 3 ac in Figure 3In h, i). Spectroscopic characterization results show that the orientation factor of the graphene oxide (GO) titanium carbide (MXene) hydrogel film in Example 3 is 0.76, the orientation factor of the CMGO film in Example 6 decreases to 0.7 after undergoing capillary shrinkage, while the CMGO film prepared by continuous vacuum filtration in Example 3 has a Herman orientation factor as high as 0.87 due to effective suppression of capillary shrinkage. Meanwhile, cross-sectional FIB-SEM images of the rGO film in Example 7 and the ΠBMG film in Example 3 show ( Figure 3 In the d and e sections, the ΠBMG film exhibits no obvious pores and possesses a denser structure. The distribution of graphene and titanium carbide (MXene) in the ΠBMG film was characterized using transmission electron microscopy. Figure 3 From f and g, it can be concluded that titanium carbide MXene is mostly distributed in monolayer form within the graphene phase. There is a significant difference in the Herman orientation factors between rGO and ΠBMG films; the rGO film has an orientation factor of only 0.74, while the ΠBMG film has an orientation factor as high as 0.88. Figure 3 h, i). Comparison of tensile strength and porosity of rGO film and ΠBMG film ( Figure 3 The tensile strength of the rGO film (j) was 0.31 GPa, and that of the ΠBMG film was 1.63 GPa; the porosity of the rGO film was 18.71%, and that of the ΠBMG film was 5.36%. This indicates that continuous vacuum filtration can effectively suppress capillary shrinkage of the film and improve the Herman orientation factor and density of the film.

[0065] Example 11

[0066] Graphene-titanium carbide (MXene) crosslinked composite film (ΠBMG) material, by effectively suppressing capillary shrinkage and introducing interfacial synergy, improves the film orientation and density, resulting in a highly oriented and dense MXene-titanium carbide crosslinked composite film material exhibiting high mechanical properties and electrical conductivity. In Example 3, after suppressing capillary shrinkage and introducing interfacial synergy, the ΠBMG film, compared to the low tensile strength (307.75 MPa) and Young's modulus (1.61 GPa) of the rGO film in Example 7, showed tensile strength and Young's modulus increases to 1628.39 MPa and 85.96 GPa, respectively. Figure 4 (a) The stress transfer efficiency between nanosheets was characterized by SEM and in-situ Raman spectroscopy. Figure 4 (bd in the text), the results show that, compared with rGO films, ΠBMG films have higher stress transfer efficiency between nanosheets. The film's ability to withstand dynamic loads was characterized by stress relaxation tests. Figure 4(e) The results show that the ΠBMG film can maintain 91% of the initial stress at 1% strain for 24000 s, which is much higher than that of the rGO film (57%). Mechanical properties were compared with other graphene films reported in the literature ( Figure 4 As shown in f), the tensile strength and Young's modulus of the ΠBMG film prepared by continuous vacuum filtration are higher than those of similar films reported in the literature. Adv. Mater. 2020, 32 , e1907411.; Nat. Commun. 2020, 11 , 1.; Nat. Mater. 2021, 20 , 624.). Furthermore, the conductivity of the ΠBMG thin film is 1423.04 S cm⁻¹. -1 It has excellent electrical conductivity.

[0067] Example 12

[0068] The self-supporting electrode fabricated based on the highly oriented, high-density graphene-titanium carbide (MXene-BMG) cross-linked composite film (ΠBMG) material of Example 3 exhibits excellent electrochemical performance (CHI 660E). The ΠBMG film shows significantly higher volumetric capacity and superior rate performance than the CΠBMG film of Example 6, at a current density of 1 A g. -1 The capacitance of the πBMG thin film is 1382 F cm⁻¹ -3 The CΠBMG film is only 488 F cm⁻¹ -3 When the current density increases to 20 A g -1 At that time, the capacity retention rate of the ΠBMG film was 52%, while that of the CΠBMG film was only 33%. Figure 5 a and b in the figure). Capacitance contribution analysis of CΠBMG thin film and ΠBMG thin film ( Figure 5 From c and d in the equation, we can conclude that the charge storage mechanism of the CΠBMG thin film and the ΠBMG thin film is a synergistic hybrid control mechanism that combines diffusion control and capacitance control. Further analysis of their energy storage mechanism reveals that at extremely low scan rates (2 mV s⁻¹), -1CE-BMG primarily exhibits diffusion control, with capacitive control gradually becoming the main contributor to capacitance as the scan rate increases. In contrast, ΠBMG is predominantly capacitively controlled at all scan rates, with its proportion gradually increasing with scan rate, but at a slower rate than CE-BMG. Furthermore, the capacitive contribution of ΠBMG is higher than that of CE-BMG at all scan rates. Since capacitive control is unaffected by the diffusion rate of ions in the material, a higher proportion of capacitive contribution indicates faster charge storage. Therefore, compared to CE-BMG, ΠBMG exhibits a faster charge storage rate. This is mainly attributed to the highly oriented and orderly layered structure of the ΠBMG film, which ensures efficient ion transport. Compared to MXene-based materials, graphene-based materials, and other carbon-based materials, ΠBMG films simultaneously possess high volumetric capacitance and mass capacitance. Figure 5 (e). Using the ΠBMG film from Example 3 as the negative electrode and the ΠBG film from Example 6 as the positive electrode, an asymmetric supercapacitor was assembled, whose energy density and power density were significantly higher than 5.5V / 100 mF (~0.52 mWh / cm). -3 ) and 2.75V / 44 mF (~ 0.65mWh cm -3 Commercial capacitors and other MXene-based capacitors ( Figure 5 (f in the text). Meanwhile, this asymmetric supercapacitor operates at 200 mV s. -1 After 40,000 cycles, the capacity retention rate remains at 100%. Figure 5 g in (the middle part).

[0069] It should be noted that, according to the above embodiments of the present invention, those skilled in the art can fully realize the scope of the independent claims and dependent claims of the present invention, and the implementation process and method are the same as those in the above embodiments; and the parts of the present invention not described in detail belong to the well-known technology in the art.

[0070] The above description is only a part of the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing graphene-titanium carbide crosslinked thin film materials, characterized in that, Includes the following steps: (1) The raw material MAX phase was chemically etched with lithium fluoride and hydrochloric acid, and reacted at 35-50℃ for 24-30 h. After washing, shaking and peeling and gradient centrifugation, a single-layer MXene nanosheet aqueous dispersion was prepared. The MAX phase was Ti3AlC2; the MXene was Ti3C2T. x The diameter of the monolayer MXene nanosheets is 5-30 micrometers. (2) The raw graphite powder is reacted with concentrated sulfuric acid and potassium permanganate at a mass fraction of 98 wt% at low temperature, and then washed and separated by gradient centrifugation to prepare a single-layer graphene oxide nanosheet aqueous dispersion; the low temperature is -5℃~10℃; the single-layer graphene oxide nanosheet has a sheet diameter of 5-30 micrometers. (3) The aqueous dispersion of monolayer MXene nanosheets in step (1) and the aqueous dispersion of monolayer graphene oxide nanosheets in step (2) are stirred and reacted to form Ti-OC covalent bonds, and a uniform dispersion of MXene nanosheets and graphene oxide nanosheets is obtained. (4) The uniform dispersion of MXene nanosheets and graphene oxide nanosheets described in step (3) is concentrated to obtain graphene oxide titanium carbide MXene hydrogel. (5) The graphene oxide titanium carbide MXene hydrogel obtained in step (4) is used to form a hydrogel membrane with a thickness of 50-3000 micrometers on a flexible porous substrate; the flexible porous substrate is a mixed cellulose ester filter membrane. (6) The graphene oxide titanium carbide MXene hydrogel membrane obtained in step (5) is used to prepare a graphene oxide titanium carbide MXene film with interlayer confined water support by continuous vacuum filtration until the film exhibits a metallic luster; the Herman orientation factor of the graphene oxide titanium carbide MXene film is 0.830-0.901; the porosity of the graphene oxide titanium carbide MXene film is 5.36%-18.71%; (7) The graphene oxide titanium carbide MXene film obtained in step (6) is reduced with a reducing agent to obtain a graphene titanium carbide MXene film. (8) The graphene titanium carbide MXene film obtained in step (7) is washed with detergent and replaced with a displacement agent, then immersed in a crosslinking agent solution for crosslinking, and dried to produce a graphene titanium carbide crosslinked film material; the displacement agent is N,N-dimethylformamide, and the crosslinking agent is an N,N-dimethylformamide solution of N-carboxysuccinimide pyrene butyrate and an N,N-dimethylformamide solution of 1-aminopyrene; In step (1), the preparation of the monolayer titanium carbide MXene nanosheet aqueous dispersion by the oscillation peeling and gradient centrifugation steps is as follows: the accordion-shaped titanium carbide MXene phase is dispersed in water, oscillated in a closed environment for 2-15 min, and then separated by gradient centrifugation to obtain the titanium carbide MXene nanosheet aqueous dispersion; in step (3), when the monolayer MXene nanosheet aqueous dispersion and the monolayer graphene oxide nanosheet aqueous dispersion are stirred and reacted, the mass ratio of monolayer MXene nanosheets to monolayer graphene oxide nanosheets is controlled between 1-50%; in step (8), the graphene titanium carbide MXene film does not undergo a drying process during the cleaning, solvent replacement and crosslinking agent soaking process; the crosslinking agent soaking time is 10-48 h.

2. The method according to claim 1, characterized in that: In step (3), the stirring reaction time is 0.5-6 h.

3. The method according to claim 1, characterized in that: In step (6), during the process of removing excess water from the graphene oxide titanium carbide MXene hydrogel membrane by continuous filtration, filtration is stopped when the membrane exhibits a metallic luster; the vacuum filtration time is 0.5-5 days.

4. The method according to claim 1, characterized in that: In step (8), the prepared graphene-titanium carbide cross-linked film material has a Herman orientation factor of 0.634-0.901 and a porosity of 5.36-32.68%.

5. The method according to claim 1, characterized in that, In step (8), the thickness of the graphene-titanium carbide cross-linked film material is 0.5-20 micrometers.

6. The application of the graphene-titanium carbide crosslinked thin film material prepared by the method according to any one of claims 1-5 in supercapacitors, characterized in that: The graphene-titanium carbide cross-linked thin film material obtained in step (8) was used directly as a self-supporting electrode to test its electrochemical performance.

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