A CF3SO3 - MXene materials containing surface groups and preparation methods and applications thereof

Abstract

The present invention relates to a method for preparing a CF3SO3 ‑ The invention relates to a MXene material having a surface group and a preparation method and application thereof, wherein the preparation method comprises the following steps: stirring and mixing a MAX phase precursor material and an etching solution containing an organic Lewis acid or an organic Lewis salt, reacting in an inert environment, washing, ultrasonicating, and centrifuging to obtain a MXene single-layer nanosheet dispersion; and then processing the dispersion to obtain a MXene single-layer nanosheet dispersion containing CF3SO3. ‑ The molecular formula of the MXene material is M n+1 X n CF3SO3, wherein M is any one or a combination of two or more of the elements Sc, Ti, V, Cr, Zr, Nb, Mo, Hf, and Ta, X is any one or a combination of two of the elements C and N, and n is 1, 2, 3, or 4. Compared with the prior art, the MAX phase material in the present invention can achieve synergistic stripping and etching, and can be prepared with high efficiency, high yield, and large scale. The preparation method is simple, easy, and environmentally friendly. The obtained MXene material has good application in the field of electrode materials for electrochemical energy storage.

Description

Technical Field

[0001] The present invention relates to the technical field of two-dimensional crystal materials, in particular to a method of preparing a CF3SO3 - MXene materials with surface groups and their preparation methods and applications. Background Art

[0002] Since the discovery of graphene in 2004, two-dimensional materials have attracted extensive attention and research due to their high specific surface area, high aspect ratio, and unique electronic structure. In 2011, Naguib et al. reported a new type of two-dimensional material called MXene. MXene materials are a type of two-dimensional carbon / nitride layer, which is usually extracted from its parent material MAX phase (M by chemical etching). n+1 AX n MXene materials are obtained by forming an atomic layer (where n = 1-3, M is a transition metal, A is a Group IIIA or IVA element, and X is C or N). Due to their rich compositional and structural controllability, unique layered structure, and high electrical conductivity, they have promising applications in electrochemical energy storage electrode materials, supercapacitor materials, electromagnetic absorption and shielding materials, and catalysts.

[0003] Generally speaking, the preparation of MXene materials is achieved by etching the MAX phase with a hydrofluoric acid (HF) solution. After HF etches away the A-layer atoms of the MAX phase, groups such as hydroxyl (-OH), oxyl (-O) and fluorine (-F) in the solution will combine with the unsaturated MX layer units to form MXene materials. Therefore, the surface groups of the MXene material obtained by this method are inevitably composed of -OH, -O, and -F, and the proportion of their components is difficult to control. Many studies have pointed out that changes in surface groups will cause changes in the electronic structure of MXene materials, which will have a profound impact on their electrical properties, magnetic properties, etc. Theoretical predictions show that MXene materials whose surface groups are all composed of -O or chlorine (-Cl) have better chemical stability and electron transport properties, and their application performance in fields such as energy storage is higher than that of MXene materials with -F surface groups. However, to date, the MXene materials currently synthesized, such as two-dimensional titanium carbide (Ti3C2T x ), titanium carbide (Ti2CT x ), two-dimensional zirconium carbide (Zr3C2T x ), niobium carbide (Nb2CT x ), tantalum carbide (Ta4C3T x ), vanadium carbide (V2CT x ), titanium nitride (Ti4N3T x ), molybdenum carbide (Mo2CT x ), Hafnium Carbide (Hf3C2T x), etc., and its surface groups T are mostly composed of -OH, -O, and -F. MXene materials with surface groups of other types (such as organic functional groups) have not been reported so far.

[0004] Environmental pollution and the presence of -F groups caused by traditional HF etching methods have significantly limited the application prospects of MXene materials. To date, etching agents such as acids, bases, or molten salts have been used to selectively remove A atoms from the MAX phase to produce accordion-shaped multilayer MXene (m-MXene) materials. However, multilayer m-MXene materials exhibit interlayer interactions, such as van der Waals forces, which prevent their subsequent exfoliation and dispersion. Intercalation and exfoliation require the use of intercalation agents such as dimethyl sulfone (DMSO), N,N-dimethylformamide (DMF), isopropylamine, hydroxycholine, n-butylamine, and tetrabutylammonium hydroxide (TBAOH). Over the years, researchers have developed a variety of etching methods, including HF etching, in-situ synthetic HF etching, alkaline etching, halogen etching, electrochemical etching, and molten salt etching. Alkaline etching tends to form insoluble Al oxides on the surface of MXene materials, hindering further etching. Halogen etching currently has reportedly low yields. Electrochemical etching can achieve fast and efficient etching of the Al layer, but achieving low-cost, mass production still faces significant challenges. Molten salt etching is a method currently attracting much attention and can produce a variety of new MXene materials without fluorine end groups. However, it requires high temperatures and a subsequent stripping process.

[0005] In summary, the preparation of MXene materials in the prior art still has the following problems: the preparation method based on in-situ synthesis HF etching has the problems of long time consumption, difficulty in peeling, low single-layer yield, etc. The main reason is that the etching process is a slow etching with stirring static state, the etching rate is slow (24 to 45 hours), and the interlayer by-products are difficult to exchange quickly, which further hinders the etching process. In addition, the H in the interlayer of the multilayer m-MXene material with a stable accordion structure is difficult to obtain. + The byproducts require a long shaking water washing and exfoliation process (about 12 hours), resulting in a long preparation time and low exfoliation yield (<70%). The existence of these problems has prevented MXene materials from meeting the requirements of commercial production. Currently, there is a lack of an efficient, high-yield, low-cost, and large-scale method for preparing MXene materials.

[0006] Therefore, developing new preparation methods to obtain MXene materials with controllable surface group types will help to regulate the many functional properties of MXene materials, improve their application in existing fields, and is expected to expand new application areas. Since 2019, a new synthetic route that omits fluoride by transferring the MAX etching process to a molten salt medium has been developed, which can generate MXenes with pure -Cl or -Br end groups. The mobility of Ti-Cl and Ti-Br surface bonds is sufficient to allow surface halogen atoms to be exchanged with other groups. However, current synthetic methods, such as the popular fluorination synthesis method and molten salt synthesis method, still make it difficult to directly obtain new organic end groups. For example, patent publication number CN116605880A discloses a method for preparing MXene nanosheets, which uses a buffered grinding aid-assisted ball milling rapid exfoliation combined with an acid / alkaline solution etching strategy to prepare MXene nanosheets with high efficiency, high yield, and large scale. The steps are: mixing a ternary MAX phase precursor material and an acid or alkaline etching solution to obtain a mixed dispersion A; mixing the dispersion A, the buffered grinding aid, and ball milling balls, and ball milling to obtain a ball milling dispersion B; centrifuging and washing the ball milling dispersion B with deionized water to obtain a mixed precipitate C; dispersing the mixed precipitate C in a dispersion solvent, ultrasonically or vortexing, and centrifuging to obtain a MXene nanosheet dispersion. Summary of the Invention

[0007] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a CF3SO3 - The MXene material with surface groups and its preparation method and application are simple and easy to prepare, environmentally friendly, and the prepared MXene material has good chemical stability, and the electrical properties and dielectric properties can be adjusted in a wide range of ways. It has good applications in the fields of electrode materials for electrochemical energy storage, supercapacitor materials, electromagnetic absorption and shielding materials, catalysts, etc.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] The present invention provides a CF3SO3 - The preparation method of the MXene material having a surface group comprises the following steps:

[0010] S1: stirring and mixing a MAX phase precursor material and an etching solution containing an organic Lewis acid solution or an organic Lewis salt solution to obtain a mixed dispersion;

[0011] S2: reacting the mixed dispersion obtained in step S1 in an inert environment, washing, ultrasonicating, and centrifuging to obtain a MXene single-layer nanosheet dispersion;

[0012] S3: The MXene monolayer nanosheet dispersion obtained in step S2 is processed to obtain a trifluoromethanesulfonate (CF3SO3 - ) is a MXene material with surface groups.

[0013] Furthermore, in step S1, the MAX phase precursor material is a general term for transition metal carbides, nitrides and carbonitrides, which include the molecular formula following M n+1 AX n Any one of the compounds (n=1, 2, 3, 4); wherein M represents a transition metal element, A is a main group III or IV element, and X is carbon (C), nitrogen (N), or C and N elements.

[0014] The M is preferably any one or a combination of two or more of scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), zirconium (Zr), niobium (Nb), molybdenum (Mo), hafnium (Hf), and tantalum (Ta). A is preferably any one or a combination of two or more of group IIIA or IVA elements. X is preferably any one or a combination of two of C and N elements.

[0015] The precursor MAX phase material is preferably titanium aluminum carbide (Ti3AlC2), titanium silicon carbide (Ti3SiC2), titanium aluminum carbide (Ti2AlC), titanium aluminum nitride (Ti2AlN), titanium aluminum nitride (Ti4AlN3), titanium gallium carbide (Ti2GaC), vanadium aluminum carbide (V2AlC), vanadium gallium carbide (V2GaC), chromium gallium nitride (Cr2GaN), chromium aluminum carbide (Cr2AlC), scandium aluminum carbide (Sc2AlC), zirconium aluminum carbide (Zr2AlC), zirconium tin carbide (Zr2SnC), niobium aluminum carbide (Nb2AlC), niobium aluminum carbide (Nb4AlC3), molybdenum aluminum carbide (Mo2AlC), molybdenum gallium carbide (Mo2GaN), hafnium aluminum carbide (Hf2AlC), hafnium aluminum carbide (Hf2AlN), tantalum aluminum carbide (Ta3AlC2), and tantalum aluminum carbide (Ta4AlC3), or a combination of two or more thereof.

[0016] Furthermore, in step S1, the organic Lewis acid solution is a trifluoromethanesulfonic acid (CF3SO3H) solution. Furthermore, the concentration of the organic Lewis acid solution is 1.5 to 3 mol / L.

[0017] Furthermore, in step S1, the organic Lewis salt solution includes one or more of zinc trifluoromethanesulfonate (Zn(CF3SO3)2) solution, scandium trifluoromethanesulfonate (Sc(CF3SO3)3) solution, copper trifluoromethanesulfonate (Cu(CF3SO3)2) solution, lithium trifluoromethanesulfonate (LiCF3SO3) solution, aluminum trifluoromethanesulfonate (Al(CF3SO3)3) solution, and silver trifluoromethanesulfonate (AgCF3SO3) solution. Furthermore, the concentration of the organic Lewis salt solution is 1.5 to 3 mol / L.

[0018] Furthermore, in step S1, the etching solution consists of the organic Lewis acid solution and water, or consists of the organic Lewis salt solution and an inorganic acid solution.

[0019] Furthermore, in step S1, the volume ratio of the organic Lewis acid solution to water is (0.5-6):1; the volume ratio of the organic Lewis salt solution to the inorganic acid solution is (0.5-6):1;

[0020] The inorganic acid solution used includes one or more of hydrochloric acid (HCl) solution, sulfuric acid (H2SO4) solution, nitric acid (HNO3) solution, and hydrofluoric acid (HF) solution; the concentration of the inorganic acid solution used is 3-12 mol / L.

[0021] Furthermore, in step S1 , the volume ratio of the MAX phase precursor material mass to the etching solution is 1 g: (6-20) mL.

[0022] Furthermore, in step S2, the inert gas used in the inert environment is argon, and the reaction time is 4 to 8 hours.

[0023] Furthermore, the washing is performed by centrifugation with deionized water at a rotation speed of 2000-4000 rpm until the pH value of the reaction product is 6-8.

[0024] Furthermore, the power of the ultrasound is 20-40W, and the time is 20-60 minutes.

[0025] Furthermore, the centrifugal speed is 2000-4000 rpm, and the time is 20-60 min.

[0026] Furthermore, in step S2, the MXene etching yield is 1% to 90%, preferably 50% to 90%, and the MXene stripping yield is 80% to 95%.

[0027] Furthermore, in step S3, when the processing is wet spinning, the MXene material is MXene fiber; when the processing is doctor blade coating or filtration, the MXene material is a MXene film; when the processing is ice template construction and freeze drying, the MXene material is a MXene block macro composite material.

[0028] Furthermore, the specific steps of obtaining MXene fibers, i.e., wet spinning, are as follows: diluting the MXene single-layer nanosheet dispersion obtained in step S2 to a concentration of 5-15 mg / mL, stirring, degassing, and uniformly dispersing it. Ammonium chloride (NH4Cl), ammonia (NH4OH), and deionized water are mixed at a ratio of (1-5) g:1 mL:(30-70) mL to prepare a coagulation bath solution. The MXene spinning solution is transferred to a 0.5-2 mL syringe and, driven by a microinjection pump, injected through a spinneret with a diameter of 300-500 μm into a rotating coagulation bath solution at a speed of 20 rpm to obtain wet MXene fibers, which are then soaked in the coagulation bath solution for 20-60 minutes, washed with a mixed solution of water and ethanol, collected on a reel, and dried in a vacuum oven at 30-50°C for 12-36 hours to obtain dry MXene fibers with a fiber diameter of approximately 40-80 μm.

[0029] Furthermore, there are two specific steps to obtain MXene films:

[0030] The first method involves blade coating to prepare MXene thin films. The MXene monolayer nanosheet dispersion obtained in step S2 is diluted to a concentration of 5-15 mg / mL, stirred, and degassed to ensure uniform dispersion. This dispersion is then blade coated onto a polyvinylidene fluoride (PVDF) film substrate using an automatic coating machine at a speed of 50-250 cm / s. The film is then vacuum-dried at 30-50°C for 12-36 hours and peeled from the PVDF film substrate to yield a large-area MXene film.

[0031] The second method is to prepare MXene thin films by filtration. The MXene single-layer nanosheet dispersion obtained in step S2 is vacuum filtered through an organic microporous filter membrane and heated in a vacuum at 30-50°C for 12-36 hours to peel off the organic microporous filter membrane to obtain a MXene thin film.

[0032] Furthermore, the specific steps for obtaining the MXene block macro-composite material are as follows: diluting the MXene single-layer nanosheet dispersion obtained in step S2 to a concentration of 5 to 15 mg / mL, stirring to uniformly disperse it, degassing it, and pouring it into a polydimethylsiloxane mold. The bottom of the mold is in contact with the surface of the steel plate, and one end is in contact with liquid nitrogen. After being completely frozen, it is sublimated at -80 to -40°C and a vacuum degree below 1 Pa for 48 to 84 hours to obtain a MXene layered skeleton aerogel block, that is, a MXene block macro-composite material.

[0033] The present invention also provides a CF3SO3 - The MXene material has a surface group and is prepared by the above-mentioned preparation method.

[0034] Furthermore, the molecular formula of the MXene is expressed as M n+1 AX n CF3SO3, of which CF3SO3 - The O atoms in the MXene nanosheet are bonded to the M atoms; the MXene single-layer nanosheet is in the form of a powder with a layer structure; the layer structure is composed of a single layer or multiple layers of M n+1 X n The lateral dimension of the layered structure is 5 to 16 μm, and the thickness of a single layer is 1.4 to 1.8 nm.

[0035] Furthermore, the MXene single-layer nanosheet dispersion can maintain a colloidal dispersion state after being left at room temperature for at least 30 days, and detection by Raman spectroscopy and infrared spectroscopy shows that the MXene single-layer nanosheets still have characteristic functional groups and structures after 30 days of standing, thus having strong antioxidant properties.

[0036] The present invention also provides a CF3SO3 - The application of MXene materials with surface groups in the fields of electrode materials for electrochemical energy storage, supercapacitor materials, electromagnetic absorption and shielding materials, and catalysts.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] (1) The present invention provides a "top-down" stripping and etching process using MAX phase precursor materials as raw materials, which can directly obtain single-layer nanosheets without the need for additional intercalation agents, and the steps are simple. By selecting raw materials and setting process parameters in the etching process, combined with chemical etching with an organic Lewis acid etching solution, the etching and rapid stripping of the ternary MAX phase precursor material are coordinated, thereby efficiently stripping and etching MXene nanosheets.

[0039] (2) The preparation method provided by the present invention is simple and easy, environmentally friendly, avoids the introduction of -F groups, and is universal and mild in conditions, greatly expanding the etching range of the MAX phase.

[0040] (3) The chemical stability of the MXene material provided by the present invention is better than that of the traditional MXene with fluorine (F) as the surface group, and its electrical properties, dielectric properties, etc. have more room for regulation.

[0041] (4) The present invention directly obtains organic functional group MXene for the first time, and the size of the nanosheets is much larger than the products obtained by the traditional HF etching method and in-situ HF acid etching, thereby improving the oxidation resistance of the MXene material.

[0042] (5) The high-concentration MXene dispersion provided by the present invention can be assembled into MXene fibers, films, and bulk macrocomposites through solution processing techniques such as wet spinning, coating, spraying, vacuum filtration, doctor blade coating, ice template construction, and freeze drying. MXene materials have good applications in the fields of electrode materials for electrochemical energy storage, supercapacitor materials, electromagnetic absorption and shielding materials, catalysts, and so on. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a flow chart for preparing the MXene material shown in Example 1;

[0044] Figure 2 XRD spectra of the Ti3C2CF3SO3 single-layer nanosheet dispersion and the precursor MAX phase Ti3AlC2 shown in Example 1;

[0045] Figure 3 This is the SEM image of the Ti3C2CF3SO3 single-layer nanosheet dispersion shown in Example 1;

[0046] Figure 4 TEM image of the Ti3C2CF3SO3 single-layer nanosheet dispersion shown in Example 1;

[0047] Figure 5 This is an optical photograph of the Ti3C2CF3SO3 thin film shown in Example 1;

[0048] Figure 6 This is the AC-TEM image of the Ti3C2CF3SO3 single-layer nanosheet dispersion shown in Example 1;

[0049] Figure 7 This is the FITR spectrum of the Ti3C2CF3SO3 single-layer nanosheet dispersion shown in Example 1. DETAILED DESCRIPTION

[0050] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the scope of protection of the present invention is not limited to the following embodiments. Based on the given embodiments, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0051] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art.

[0052] In the following examples, Ti3AlC2, Ti3SiC2, Ti2AlC, Ti2AlN, Ti4AlN3, Ti2GaC, V2AlC, V2GaC, Cr2GaN, Cr2AlC, Sc2AlC, Zr2AlC, Zr2SnC, Nb2AlC, Nb4AlC3, Mo2AlC, Mo2GaN, Hf2AlC), Hf2AlN, Ta3AlC2, Ta4AlC3, and CF3SO3H were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. with a purity of ≥90 wt% and a particle size of 0.5-25 μm; Zn(CF3SO3)2, Sc(CF3SO3)3, Cu(CF3SO3)2, LiCF3SO3, Al(CF3SO3)3, and AgCF3SO3 were all analytically pure and purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. All of the above drugs are commercially available and were used without purification.

[0053] Example 1

[0054] In this embodiment, the MXene single-layer nanosheet dispersion is a Ti3C2CF3SO3 single-layer nanosheet dispersion, the MXene material is a Ti3C2CF3SO3 film, the precursor MAX phase is Ti3AlC2, and the etching solution is an organic Lewis acid CF3SO3H.

[0055] A CF3SO3 - Preparation method of MXene materials with surface groups, such as Figure 1 As shown, the following steps are included:

[0056] 5 mL of a 1.5 mol / L CF3SO3H solution and 5 mL of deionized water were measured and magnetically stirred in a Teflon beaker at room temperature for 5 minutes. 0.5 g of 10 μm Ti3AlC2 powder was slowly added, and the mixture was allowed to react at room temperature for 6 hours under an inert atmosphere. The reaction product was washed with deionized water at 3500 rpm to a pH of 7, ultrasonically sonicated at 20 W for 30 minutes, and then centrifuged at 3500 rpm for 30 minutes to obtain a dispersion of Ti3C2CF3SO3 monolayer nanosheets.

[0057] Take 5 mL of Ti3C2CF3SO3 single-layer nanosheet dispersion, vacuum filter it through a 0.4 μm organic microporous filter membrane, and vacuum heat it at 40°C for 24 h to peel off the organic microporous filter membrane to obtain a Ti3C2CF3SO3 film with a diameter of 4 cm.

[0058] The prepared Ti3C2CF3SO3 single-layer nanosheet dispersion and the precursor MAX phase Ti3AlC2 were analyzed by X-ray diffraction (XRD). Figure 2 As shown in the figure, by comparison, it can be seen that after the reaction, the intensity of the diffraction peaks (104) and (105) of the Ti3C2CF3SO3MXene powder material is significantly weakened, indicating that the degree of order along the crystal plane of the product decreases; the diffraction peaks (002) and (004) are significantly shifted to lower angles. The above XRD pattern changes are consistent with the changes in the preparation of Ti3C2 MXene powder material using HF etching of Ti3AlC2, indicating that the Al atoms located between the Ti3AlC2 layers are extracted and new atoms are embedded.

[0059] The prepared Ti3C2CF3SO3 single-layer nanosheet dispersion was subjected to scanning electron microscopy (SEM) testing. Figure 3 As shown in the figure, it can be seen that it exhibits a distinct nanosheet morphology unique to MXene materials. This is because the Al atoms located between the Ti3C2 layers are extracted and the newly embedded CF3SO3 - The atoms cause the bonding between Ti3C2 layers to weaken, the interlayer spacing to increase, and then through gentle ultrasound and centrifugal separation, a single-layer structure is revealed. According to statistics, the main size distribution is around 4μm, which is much larger than the product of HF etching.

[0060] The prepared Ti3C2CF3SO3 single-layer nanosheet dispersion was subjected to transmission electron microscopy (TEM) testing. Figure 4 As shown, the ultra-thin characteristics of the nanosheets can also be seen.

[0061] Figure 5 An optical photograph of the Ti3C2CF3SO3 film was taken, and it was found that the diameter of the Ti3C2CF3SO3 film was 4 cm.

[0062] The prepared Ti3C2CF3SO3 single-layer nanosheet dispersion was subjected to spherical aberration scanning transmission microscopy (AC-TEM) test, as shown in Figure 2. Figure 6 As shown in the figure, the atomic arrangement of Ti3C2CF3SO3 MXene single-layer nanosheets was confirmed. From this figure, it can be clearly seen that CF3SO3 combined with Ti3C2 layer - , which strongly confirmed that the reaction product was Ti3C2CF3SO3.

[0063] The prepared Ti3C2CF3SO3 single-layer nanosheet dispersion was subjected to Fourier transform infrared spectroscopy (FITR) analysis. Figure 7 As shown, CF3SO3 was found - characteristic peaks, which also proves that CF3SO3 - For the end group.

[0064] Example 2

[0065] Compared with Example 1, most of the steps are the same, except that the precursor MAX phase is adjusted to Ti3SiC2, and the etching solution is adjusted to a mixed solution of 2 mL 1.5 mol / L Zn(CF3SO3)2 and 4 mL 3 mol / L HCl.

[0066] Example 3

[0067] Compared with Example 1, most of the steps are the same, except that the precursor MAX phase is adjusted to Ti2AlC, and the etching solution is adjusted to a mixed solution of 3 mL 2 mol / L Sc(CF3SO3)3 and 3 mL 6 mol / L H2SO4.

[0068] Example 4

[0069] Compared with Example 1, most of the steps are the same, except that the precursor MAX phase is adjusted to Ti2AlN, and the etching solution is adjusted to a mixed solution of 3 mL 3 mol / L Cu(CF3SO3)2 and 2 mL 9 mol / L HNO3.

[0070] Example 5

[0071] Compared with Example 1, most of the steps are the same, except that the precursor MAX phase is adjusted to Ti4AlN3, and the etching solution is adjusted to a mixed solution of 6 mL 2 mol / L LiCF3SO3 and 1 mL 12 mol / L HNO3.

[0072] Example 6

[0073] Compared with Example 1, most of the steps are the same, except that the precursor MAX phase is adjusted to Ti2GaC, and the etching solution is adjusted to a mixed solution of 2 mL 2 mol / L Al(CF3SO3)3 and 1 mL 12 mol / L HF.

[0074] Example 7

[0075] Compared with Example 1, most of the steps are the same except that the precursor MAX phase is adjusted to V2AlC.

[0076] Example 8

[0077] Compared with Example 1, most of the steps are the same, except that the precursor MAX phase is adjusted to V2GaC3.

[0078] Example 9

[0079] Compared with Example 1, most of the steps are the same except that the precursor MAX phase is adjusted to Cr2GaN.

[0080] Example 10

[0081] Compared with Example 1, most of the above are the same, except that the precursor MAX phase is adjusted to Cr2AlC.

[0082] Example 11

[0083] Compared with Example 1, most of the steps are the same except that the precursor MAX phase is adjusted to Sc2AlC.

[0084] Example 12

[0085] Compared with Example 1, most of the steps are the same except that the precursor MAX phase is adjusted to Zr2AlC.

[0086] Example 13

[0087] Compared with Example 1, most of the steps are the same except that the precursor MAX phase is adjusted to Zr2SnC.

[0088] Example 14

[0089] Compared with Example 1, most of the details are the same, except that the precursor MAX phase is adjusted to Nb2AlC.

[0090] Example 15

[0091] Compared with Example 1, most of the details are the same, except that the precursor MAX phase is adjusted to Nb4AlC3.

[0092] Example 16

[0093] Compared with Example 1, most of the steps are the same except that the precursor MAX phase is adjusted to Mo2AlC.

[0094] Example 17

[0095] Compared with Example 1, most of the steps are the same except that the precursor MAX phase is adjusted to Mo2GaN.

[0096] Example 18

[0097] Compared with Example 1, most of the steps are the same except that the precursor MAX phase is adjusted to Hf2AlC.

[0098] Example 19

[0099] Compared with Example 1, most of the steps are the same except that the precursor MAX phase is adjusted to Hf2AlN.

[0100] Example 20

[0101] Compared with Example 1, most of the details are the same, except that the precursor MAX phase is adjusted to Ta3AlC2.

[0102] Example 21

[0103] Compared with Example 1, most of the steps are the same except that the precursor MAX phase is adjusted to Ta4AlC3.

[0104] Comparative Example 1

[0105] A type of F - The preparation method of MXene materials with surface groups is as follows:

[0106] 20 mL of 9 mol / L HCl and 1.6 g of LiF were stirred in a Teflon container for 5 minutes. 0.5 g of 10 μm Ti3AlC2 powder was slowly added, and the mixture was stirred continuously at 40°C for 30 hours. The reaction product was washed with deionized water by centrifugation at 3500 rpm to a pH of 7. The swelled sediment was diluted with deionized water and gently sonicated in an ice bath under argon (Ar) for 1 hour. The mixture was then centrifuged at 3500 rpm for 30 minutes to remove any undislodged particles, yielding a dispersion of Ti3C2F3 monolayer nanosheets.

[0107] 5 mL of Ti3C2F dispersion was vacuum filtered through a 0.4 μm organic microporous filter membrane and heated under vacuum at 40 °C for 24 h to peel off the organic microporous filter membrane to obtain a Ti3C2F film.

[0108] The performance tests were performed on the Ti3C2CF3SO3 single-layer nanosheet dispersion and Ti3C2CF3SO3 film obtained in Examples 1 to 3 and the Ti3C2F single-layer nanosheet dispersion and Ti3C2F film obtained in Comparative Example 1. The Ti3C2CF3SO3 single-layer nanosheet dispersion and the Ti3C2F single-layer nanosheet dispersion are collectively referred to as MXene single-layer nanosheet dispersion, and the Ti3C2CF3SO3 film and the Ti3C2F film are collectively referred to as MXene film.

[0109] Detection method:

[0110] Antioxidation property: When the MXene single-layer nanosheet dispersion is allowed to stand at room temperature, if the MXene single-layer nanosheet dispersion can still maintain a colloidal dispersion state and the single-layer nanosheets still have characteristic functional groups and structures when detected by Raman and infrared spectroscopy, it can be said to have antioxidant property, which is expressed by the number of days of standing.

[0111] Etching yield: The etching yield of the MXene monolayer nanosheet dispersion was obtained by comparing the mass of the precursor MAX phase Ti3AlC2. The calculation formula is as follows:

[0112] Y KS =M MXene / M MAX ×100%

[0113] M MXene =M LM+MXene -M LM

[0114] Among them, Y KS represents the etching yield of MXene single-layer nanosheet dispersion, M MXene Indicates the quality of MXene film, M MAX Indicates the mass of the precursor MAX phase Ti3AlC2, M LM+MXene represents the mass of the organic microporous filter membrane and MXene film after vacuum heating, M LM Indicates the quality of organic microporous filter membrane.

[0115] Stripping yield: The ratio of the actual mass to the theoretical mass during the stripping process of the MXene film from the organic microporous filter membrane. The calculation formula is as follows:

[0116] Y BL =M MXene ' / M MXene

[0117] M MXene =M LM+MXene -M LM

[0118] Among them, MMXene ' represents the actual mass of the MXene film peeled off from the organic microporous filter membrane.

[0119] Etching time: the reaction time between the precursor MAX phase and the etching solution.

[0120] Nanosheet size: The prepared MXene single-layer nanosheet dispersion was subjected to scanning electron microscopy (SEM) testing, and the main size distribution was statistically analyzed to obtain the nanosheet size.

[0121] Detection method: as shown in Table 1.

[0122] Table 1 Performance test results of MXene single-layer nanosheet dispersion and MXene film

[0123] Example 1 Example 2 Example 3 Comparative Example 1 Antioxidant properties >30 days >30 days >30 days <7 days Etching yield 90％ 88％ 89％ 52％ Stripping yield 95％ 87％ 93％ 51％ Etching time 6h 6h 6h 24h Nanosheet size 4.0μm 15.0μm 8.1μm 0.5μm

[0124] It can be seen from the above table that the preparation method of the present invention can efficiently, high-yield and universally prepare large-sized (micrometer-level) single-layer MXene nanosheets. The MXene single-layer nanosheet dispersions of Examples 1 to 3 can be stably stored for more than 30 days at room temperature and have strong antioxidant properties. The etching yield of the MXene single-layer nanosheet dispersions of Examples 1 to 3 can be as high as 90%, which is 52% higher than the etching yield of the MXene single-layer nanosheet dispersion of Comparative Example 1. The stripping yield of the MXene single-layer nanosheet dispersions of Examples 1 to 3 can reach up to 95%, which is 51% higher than the stripping yield of the MXene single-layer nanosheet dispersion of Comparative Example 1. The lateral size of the nanosheets in the MXene nanosheet dispersions of Examples 1 to 3 reaches up to 15.0 μm, and the thickness is a single layer, while the MXene nanosheets finally obtained in Comparative Example 1 are all nanometer-sized (with an average size of 0.5 μm), and the obtained nanosheets are smaller in size. Meanwhile, the preparation of the MXene nanosheet dispersion of Comparative Example 1 takes a long time, requiring 24 hours, while the preparation method of the present invention can complete the etching in only 6 hours.

[0125] In summary, compared with existing materials, the above embodiments of the present invention provide CF3SO3 - The preparation method of MXene materials with surface groups is simple, easy and environmentally friendly, avoiding many shortcomings of the traditional hydrofluoric acid etching method for preparing MXene materials. The obtained CF3SO3 - MXene with surface groups can not only improve its antioxidant properties, but also has good applications in the fields of electrode materials for electrochemical energy storage, supercapacitor materials, electromagnetic absorption and shielding materials, catalysts, etc.

[0126] Although the present invention has been described in detail above using general explanations, specific embodiments, and experiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A CF3SO3 - A method for preparing a MXene material having a surface group, characterized in that: The following steps are involved: S1: stirring and mixing a MAX phase precursor material and an etching solution containing an organic Lewis acid solution or an organic Lewis salt solution to obtain a mixed dispersion, wherein the etching solution consists of the organic Lewis acid solution and water, or consists of the organic Lewis salt solution and an inorganic acid solution; S2: reacting the mixed dispersion obtained in step S1 in an inert environment, washing, ultrasonicating, and centrifuging to obtain a MXene single-layer nanosheet dispersion; S3: The MXene single-layer nanosheet dispersion obtained in step S2 is processed to obtain CF3SO3 - MXene materials with surface groups.

2. A CF3SO3 according to claim 1 - A method for preparing a MXene material having a surface group, characterized in that: In step S1, the MAX phase precursor material is a general term for transition metal carbides, nitrides and carbonitrides, which includes the molecular formula following M n+1 AX n Any one of the compounds of (n=1, 2, 3, 4); wherein M represents a transition metal element, A is a main group III or IV element, and X is carbon, nitrogen, or a carbon-nitrogen element.

3. A CF3SO3 according to claim 2 - A method for preparing a MXene material having a surface group, characterized in that: In step S1, the precursor MAX phase material includes any one or more of Ti3AlC2, Ti3SiC2, Ti2AlC, Ti2AlN, Ti4AlN3, Ti2GaC, V2AlC, V2GaC, Cr2GaN, Cr2AlC, Sc2AlC, Zr2AlC, Zr2SnC, Nb2AlC, Nb4AlC3, Mo2AlC, Mo2GaN, Hf2AlC, Hf2AlN, Ta3AlC2, and Ta4AlC3.

4. A CF3SO3 according to claim 1 - A method for preparing a MXene material having a surface group, characterized in that: In step S1, the organic Lewis acid solution is a CF3SO3H solution; The organic Lewis salt solution includes one or more of Zn(CF3SO3)2 solution, Sc(CF3SO3)3 solution, Cu(CF3SO3)2 solution, LiCF3SO3 solution, Al(CF3SO3)3 solution, and AgCF3SO3 solution.

5. A CF3SO3 according to claim 1 - A method for preparing a MXene material having a surface group, characterized in that: In step S1, the volume ratio of the organic Lewis acid solution to water is (0.5:6):1; the volume ratio of the organic Lewis salt solution to the inorganic acid solution is (0.5:6):1; The inorganic acid solution used includes one or more of HCl solution, H2SO4 solution, HNO3 solution and HF solution; the concentration of the inorganic acid solution used is 3-12 mol / L.

6. A CF3SO3 according to claim 1 - A method for preparing a MXene material having a surface group, characterized in that: In step S1 , the mass ratio of the MAX phase precursor material to the volume of the etching solution is 1 g: (6-20) mL.

7. A CF3SO3 according to claim 1 - A method for preparing a MXene material having a surface group, characterized in that: In step S3, when the processing is wet spinning, the MXene material is MXene fiber; when the processing is coating, spraying, vacuum filtration, or doctor coating, the MXene material is a MXene film; when the processing is ice template construction or freeze drying, the MXene material is a MXene block macro-composite material.

8. A CF3SO3 - The MXene material has a surface group, which is prepared by the preparation method according to any one of claims 1 to 7.

9. The method of claim 8 using CF3SO3 - The application of MXene materials with surface groups in the fields of electrode materials for electrochemical energy storage, supercapacitor materials, electromagnetic absorption and shielding materials, and catalysts.

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