MXene nanorolls, composites, and methods of making and uses thereof

Abstract

The application discloses a kind of MXene nanometer roll, composite material and its preparation method and use, wherein, the MXene nanometer roll is a kind of MXene material with one-dimensional hollow roll structure, by two-dimensional MXene material curling self-assembly is obtained, break the cognition of people to MXene material belongs to two-dimensional material.The application further provides the preparation method of MXene nanometer roll, steps include: two-dimensional MXene material or etching MAX phase material is obtained accordion appearance etching material, dispersed in liquid phase containing positive ion pair reagent, under the action of external force, obtain MXene nanometer roll, preparation method is simple and easy to operate.The MXene nanometer roll of the application and carbon nanotube all have one-dimensional nanostructure, can be used as alternative material to replace carbon nanotube;Since the application also has the characteristics of distinguishing carbon nanotube, more new field applications can be realized, such as as slow-release material etc.

Description

Technical Field

[0001] This invention belongs to the field of new materials, and in particular relates to an MXene nanoroll, a composite material, its preparation method and applications. Background Technology

[0002] MXene is a class of metal carbide or nitride materials with a two-dimensional layered structure, derived from ternary layered ceramic materials. n+1 AX n (M represents a transition metal element, A a main group element, X a C / N / B element, and n is typically 1–3). During the etching process, the large number of residual functional groups (-F, -OH, -O, etc.) on the MXene surface endows it with good hydrophilicity, while MXene also exhibits excellent electrical conductivity (6000-8000 S cm⁻¹). -1 With its excellent thermal conductivity, adjustable bandgap, and outstanding mechanical strength, MXene has broad application prospects in energy conversion and storage, electromagnetic shielding, sensing, and environmental protection. However, similar to other two-dimensional materials, MXene also exhibits a tendency for disordered powder "face-to-face" stacking and agglomeration in practical applications, which greatly limits its performance.

[0003] Constructing multidimensional MXene assemblies, which allows for the manipulation of the microstructure of MXene nanosheets while reflecting the superior nanoscale performance of MXene at the macroscopic level, is an important step in expanding the practical applications of MXene. However, during the construction of MXene assemblies, factors such as size inhomogeneity, low yield, assembly agglomeration, and high quality requirements for MXene sheets all limit the performance of MXene assemblies. Therefore, there is an urgent need to develop a simple MXene self-assembly technology. Summary of the Invention

[0004] MXene materials are obtained by etching the A component of a ternary layered ceramic material (MAX phase material). Currently, those skilled in the art generally believe that MXene materials are structurally similar to graphene and are typical two-dimensional materials. However, this invention provides a novel MXene nanomaterial with a one-dimensional hollow roll structure, overturning the common perception that MXene materials are two-dimensional. This invention also provides a method for preparing this MXene nanoroll, which is obtained by self-assembly of two-dimensional MXene materials through rolling.

[0005] The first aspect of the present invention is to provide an MXene material having a novel one-dimensional hollow roll structure, namely MXene nanorolls, which are formed by rolling up two-dimensional MXene material; the chemical formula of the MXene nanorolls is M n+ 1X n T xWhere M is selected from one or more transition metal elements, X is selected from one, two, or three of carbon, nitrogen, or boron elements, n is between 1, 2, 3, or 4, and T x For functional groups.

[0006] In some embodiments, the aforementioned transition metal element is selected from one, two, or three of the following: Ti, V, Nb, Cr, Ta, Hf, Mo, W, Fe, Mn, Y, or Sc; and / or, the functional group T of the aforementioned MXene nanorolls. x Includes elements of the sixth and / or seventh primary families.

[0007] In some embodiments, the hollow roll structure is formed by rolling up a two-dimensional MXene material; and / or, the MXene nanoroll has openings at both ends; and / or, the one-dimensional morphology of the MXene nanoroll is linear; and / or, the hollow roll structure is formed by rolling up a single sheet and / or a single layer of two-dimensional MXene material.

[0008] In some embodiments, the wall thickness of the MXene nanoroll is between 0.3 nm and 50 nm; and / or, the length of the MXene nanoroll is between 0.1 μm and 100 μm; and / or, the diameter of the MXene nanoroll is between 10 nm and 200 nm.

[0009] In some embodiments, the wall thickness of the MXene nanoroll is between 1 nm and 6 nm; and / or, the length of the MXene nanoroll is between 1 μm and 10 μm; and / or, the diameter of the MXene nanoroll is between 10 nm and 100 nm.

[0010] A second aspect of the present invention provides an aggregate of MXene nanorolls, the aggregate comprising: the aforementioned MXene nanorolls, wherein the MXene nanorolls are monodisperse.

[0011] A third aspect of the present invention also provides a method for preparing the above-mentioned MXene nanorolls, characterized in that the steps include: dispersing an accordion-shaped etched material obtained by etching a two-dimensional MXene material or a MAX phase material in a liquid phase containing a positive ion pair reagent, forming a liquid phase flow under the action of an external force to obtain the MXene nanorolls.

[0012] In some embodiments, the positive ion-pairing reagent is an alkyl quaternary ammonium compound; preferably, the positive ion-pairing reagent is selected from one or more of tetramethylamine hydroxide, tetraethylamine hydroxide, tetrapropylamine hydroxide, tetrabutylamine hydroxide, or tetrapentylamine hydroxide; and / or, the mass content of the positive ion-pairing reagent in the liquid phase is between 1 wt.% and 30 wt.%; and / or, the external force is: stirring, or stirring and ultrasound; preferably, the stirring is directional rotation to form directional liquid phase flow; and / or, the liquid phase includes one or more of water, ethanol, and isopropanol.

[0013] A fourth aspect of the present invention also provides an MXene nanoroll composite material comprising: the MXene nanorolls described above; or, MXene nanorolls obtained by the preparation method described above; and a matrix material selected from one or more of metals, metal compounds, polymers, and inorganic nonmetals.

[0014] In some embodiments, the hollow rolls of the MXene nanorolls contain a filling material; and / or, in the composite material, the mass content of the MXene nanorolls is between 0.01 wt.% and 99 wt.%.

[0015] In some embodiments, the metal is selected from one or more of alkali metals or alkaline earth metals and transition metals; or, liquid metals such as mercury, gallium, rubidium, and cesium; the metal compound is selected from one or more of iron oxide, tin oxide, cobalt oxide, molybdenum oxide, molybdenum sulfide, lithium lanthanum zirconium oxide, lithium germanium phosphorus sulfide, lithium silicon phosphorus sulfide, and lithium phosphorus sulfide; the polymer is selected from one or more of latex, rubber, polyvinyl chloride, polyethylene terephthalate, polypropylene, polyethylene oxide, polytetrafluoroethylene, polyurethane, polyaniline, polypyrrole, and polythiophene; the inorganic non-metal is selected from at least one of sulfur, silicon, iodine, bromine, silicon oxide, and silicon suboxide.

[0016] The fifth aspect of the present invention also provides a method for preparing an MXene nanoroll composite material, wherein the matrix material is a metal, and the steps include: converting the metal into a liquid state and then mixing or contacting it with MXene nanorolls.

[0017] The sixth aspect of the present invention also provides a method for preparing an MXene nanofiber composite material, wherein the matrix material is a metal compound or an inorganic non-metallic material, and the steps include: mixing the powder of the metal compound or the inorganic non-metallic material, a binder, MXene nanofibers, and a solvent to form a slurry, coating it into a film, and drying it to obtain the final product; or mixing the powder of the metal compound or the inorganic non-metallic material, the binder, and the MXene nanofibers and pressing it to obtain the final product; or dissolving the metal compound or the inorganic non-metallic material in a solvent, mixing it with the MXene nanofibers, and drying the final product.

[0018] The sixth aspect of the present invention also provides a method for preparing an MXene nanoroll composite material, wherein the matrix material is a polymer, and the steps include: mixing the MXene nanoroll with the polymer to obtain the composite material; or, mixing the MXene nanoroll with the prepolymer or monomer of the polymer and then initiating polymerization to obtain the composite material.

[0019] The sixth aspect of the present invention also provides a method for preparing MXene nanoroll composite material, wherein the matrix material is a metal compound, and the steps include: mixing the MXene nanoroll with a metal salt solution and obtaining it through a reduction reaction.

[0020] The seventh aspect of the present invention also provides the use of MXene nanorolls as a filter material, adsorbent material, sustained-release material, microwave absorbing material, catalyst carrier, electrocatalytic material, and modified material.

[0021] The MXene nanorolls of this invention have significantly different structural features compared to typical one-dimensional materials—carbon nanotubes, including:

[0022] 1. The MXene nanorolls of this invention are obtained by rolling up two-dimensional materials, exhibiting a linear one-dimensional structure. The aggregates of MXene nanorolls exhibit monodisperse characteristics. This differs from carbon nanotubes, which are grown at high temperatures using carbon source gas under the action of a catalyst, exhibiting a curved one-dimensional structure. The aggregates of carbon nanotubes exhibit an aggregated state of one-dimensional nanowires intertwined. Therefore, compared to carbon nanotubes, the aggregates of MXene nanorolls of this invention have the characteristic of being easily dispersed.

[0023] 2. The MXene nanorolls of the present invention are formed by rolling up two-dimensional materials, thus having an open structure at both ends; the carbon nanotubes are obtained by high-temperature growth of a catalyst, and their two ends are closed.

[0024] 3. The MXene nanorolls of the present invention belong to MXene materials, which are composed of transition metal elements and non-metal elements (carbon and / or nitrogen and / or boron) and surface functional groups, and have the hydrophilicity of MXene materials; while carbon nanotubes are composed of carbon elements and have a hydrophobic surface.

[0025] 4. The one-dimensional morphology of the MXene nanorolls of the present invention is a hollow roll structure formed by rolling two-dimensional materials, so the diameter of the hollow tube can be adjusted by the interlayer slippage of the roll, thereby giving the MXene nanorolls structural elasticity; while carbon nanotubes are closed hollow tubular structures, the diameter of which cannot be adjusted and do not have structural elasticity.

[0026] 5. The diameter range of the MXene nanorolls of the present invention (10nm to 200nm) is larger than that of carbon nanotubes (2nm to 30nm); combined with the structural feature of the MXene nanorolls with open ends, the hollow interior of the MXene nanorolls of the present invention can be filled with materials, thereby obtaining a one-dimensional nanocomposite material with a coating structure; while carbon nanotubes are difficult to prepare one-dimensional nanocomposite materials due to the sealing of both ends and the small diameter.

[0027] The present invention has MXene nanorolls and carbon nanotubes, both of which have one-dimensional nanostructures and can be used as alternative materials to replace carbon nanotubes. Since the present invention also has characteristics that distinguish it from carbon nanotubes, it can realize more new applications, such as as a sustained-release material. Attached Figure Description

[0028] Figure 1 This is a schematic diagram illustrating the formation of the MXene nanorolls of the present invention;

[0029] Figure 2 The XRD spectra of the MAX phase material and the two-dimensional MXene material in Example 1 of this invention are shown.

[0030] (a); SEM images of the MAX phase material (b) and the etched material (c, d);

[0031] Figure 3 In Example 1 of this invention, the mass concentration of the positive ion pair reagent was 1 wt.% (a) and 5 wt.%.

[0032] (b), 10 wt.% (c), 20 wt.% (d) SEM images of samples obtained with stirring;

[0033] Figure 4 SEM image of a sample obtained in Example 1 of this invention with a positive ion-pairing reagent concentration of 20 wt.% but without stirring;

[0034] Figure 5 TEM image (a) and tube diameter distribution statistics (b) of MXene nanorolls obtained in Example 1 of this invention;

[0035] Figure 6 These are TEM images (a and b) and HRTEM images (c and d) of MXene nanorolls at different magnifications in Example 1 of the present invention.

[0036] Figure 7 This is an elemental distribution diagram of the MXene nanorolls in Example 1 of the present invention;

[0037] Figure 8 XRD patterns (a) of the MAX phase material and the two-dimensional MXene material in Embodiment 2 of the present invention; SEM images of the MAX phase material (b) and the two-dimensional MXene material (c);

[0038] Figure 9 TEM image (a) and tube diameter distribution statistics (b) of MXene nanorolls obtained in Example 2 of this invention;

[0039] Figure 10 The images shown are TEM images (a) and HRTEM images (b and c) at different magnifications of MXene nanorolls in Example 2 of this invention, and elemental distribution images (e-j).

[0040] Figure 11 XRD patterns (a) of the MAX phase material and the two-dimensional MXene material in Embodiment 3 of the present invention; SEM images of the MAX phase material (b) and the two-dimensional MXene material (c);

[0041] Figure 12 The images are SEM images of the two-dimensional MXene material in Example 3 of the present invention at stirring times of 1 min (a), 10 min (b), and 30 min (c).

[0042] Figure 13 V2AlC and V2CT in Embodiment 4 of the present invention x XRD patterns (a), SEM images of V2AlC (b), SEM (c), TEM (d), and HRTEM (e) images of MXene nanorolls;

[0043] Figure 14 These are SEM images of MXene nanorolls (a), the composite of MXene nanorolls and elemental sulfur (b), and MXene nanorolls@S (c) in Example 5 of this invention.

[0044] Figure 15 SEM images (a) and (b) of the surface of the MXene nanofilm in Example 7 of this invention are shown.

[0045] Figure 16 The images show (a) and (b) the initial placement of MXene nanorolls into molten lithium in Example 7 of this invention, and (c) a photograph of the MXene nanoroll@lithium composite material.

[0046] Figure 17These are SEM images of the surface of the MXene nanoroll@lithium composite material in Example 7 of this invention at different magnifications;

[0047] Figure 18 These are SEM images of the cross-sections of the MXene nanoroll@lithium composite material in Example 7 of this invention at different magnifications.

[0048] Figure 19 This is an HRTEM image of the MXene nanoroll@lithium composite material in Example 7 of the present invention. Detailed Implementation

[0049] The technical solution of the present invention is illustrated below through specific embodiments. It should be understood that the one or more steps mentioned in the present invention do not preclude the existence of other methods and steps before or after the combined steps, or that other methods and steps may be inserted between these explicitly mentioned steps. It should also be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Unless otherwise stated, the numbering of each method step is only for the purpose of identifying each method step, and not for limiting the order of each method or limiting the scope of the present invention. Changes or adjustments to their relative relationships, without substantial changes to the technical content, can also be considered as within the scope of the present invention.

[0050] The raw materials and instruments used in the examples are not subject to any specific restrictions on their source; they can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0051] The MXene nanorolls of this invention represent a microstructural alteration of MXene materials while retaining their inherent material properties, such as conductivity and hydrophilicity. Because these MXene nanorolls are formed by rolling up two-dimensional MXene materials, they possess unique nanostructures. For example, the hollow roll structure provides structural elasticity; the open ends and appropriate aspect ratio enable liquid impregnation, resulting in a one-dimensional coated composite material. Combining these material and structural properties, this invention provides a novel one-dimensional nanomaterial.

[0052] The technical feature of the preparation method of the MXene nanorolls of the present invention is that the two-dimensional MXene material is dispersed in a liquid phase containing a positive ion pair reagent, and liquid phase flow is generated under the action of external force (such as stirring), so that the two-dimensional MXene material is rolled up to form a hollow roll structure.

[0053] Ion-pairing reagents are neutral ion pairs formed by strongly hydrophilic ions that react with sample molecules. They are specialized reagents for high-performance liquid chromatography (HPLC). Ion-pairing reagents are commonly used in HPLC analysis of highly ionized samples where the sample retention time on a reversed-phase column is very short or nonexistent. In such cases, appropriate ion-pairing reagents are added to bind the ions on the analyte, forming molecules retained on the column. The ion-pairing reagent acts like an adhesive, attracting the analyte with ions on one end and interacting with the stationary phase with its carbon chain on the other, thus holding the analyte on the stationary phase. Ion-pairing reagents can be either positive or negative ion-pairing reagents; negative ion-pairing reagents are used for analyzing alkaline samples, while positive ion-pairing reagents are used for analyzing acidic samples.

[0054] The mechanism by which two-dimensional MXene materials can form curls is not yet clear. The applicant believes that the formation mechanism of the MXene nanorolls of the present invention is as follows: Figure 1 As shown, since the surface of two-dimensional MXene materials usually has abundant oxygen-containing functional groups such as -OH, they are negatively charged. Therefore, positively charged ion-pair reagents in the liquid phase can be adsorbed onto the negatively charged two-dimensional MXene materials. Since the positively charged ion-pair reagents also contain carbon chains, under the action of external forces (such as stirring), liquid phase flow is formed. Through the force transmitted by the carbon chains, the two-dimensional MXene materials are curled up, eventually forming a one-dimensional hollow nanoroll structure.

[0055] It is evident that the necessary conditions for the preparation method of the present invention to function include: 1) adding a positive ion pairing reagent to the liquid phase; 2) applying an external force to cause the liquid phase to flow and form a curling force; wherein, in the present invention, the positive ion pairing reagent has the following function: one end can generate a charge interaction with the surface of the two-dimensional MXene material to form a strong connection, and the other end has an alkyl chain that can transmit the external force to cause the two-dimensional MXene material to curl; that is to say, the meaning of the positive ion pairing reagent in the present invention is not limited to existing reagents used in liquid chromatography. Other types of chemical reagents that produce the same function or effect, such as some cationic surfactants (e.g., quaternary ammonium salt cationic surfactants), also fall within the scope of the positive ion pairing reagent of the present invention in the technical concept of the present invention.

[0056] The external force applied in this invention can be stirring or other forms of liquid phase flow (such as height difference). Of course, the flexibility and charge of the two-dimensional MXene material are also inherent conditions that enable it to generate and maintain curling.

[0057] The surface tension of the solvent in the liquid phase affects the dispersion of two-dimensional MXene materials. In some embodiments, the solvent can be a mixture of water and alcohol. By adjusting the surface tension of the solvent through different ratios, the two-dimensional MXene materials can be fully dispersed.

[0058] Example 1

[0059] This embodiment provides an MXene nanoroll with the chemical formula V2B. 0.28 C 0.57 N 0.15 T x The specific steps of the preparation method are as follows:

[0060] 1) Preparation of two-dimensional MXene materials from MAX phase materials

[0061] MAX phase material V2AlB 0.28 C 0.57 N 0.15 Etching was performed at 90°C for 48 hours using an etchant to obtain a mixture (5 mg / ml) containing the etchant. The etchant was a mixture of concentrated hydrochloric acid (30 wt.%) and NaF, with a molar ratio of NaF to HCl of 1:1. The resulting etchant was a two-dimensional MXene material, labeled as V2(B). x C y N 1-x-y )T x ;

[0062] After centrifuging and washing the mixture containing the etching material, the resulting etching material was characterized. Figure 2 XRD comparison of the MAX phase material and the etched material shows that the (002) diffraction peak of the etched material shifts to a lower angle, and the characteristic peaks of other MAX phases disappear. This is because the A component (Al element) in the MAX phase material is selectively etched, resulting in a two-dimensional MXene material with increased interlayer spacing between the sheets. SEM images show that the MAX phase material exhibits a typical layered bulk morphology. Figure 2 b); while the etched material exhibits a sheet-like, stacked accordion-like morphology ( Figure 2 (c) and (d) show a significant increase in interlayer spacing, consistent with the previous XRD pattern results. Figure 2 c also shows that the etched material has a sheet diameter of about 1μm to 10μm, with most of the sheets having a diameter of about 5μm.

[0063] 2) Fabrication of MXene nanorolls from two-dimensional MXene materials

[0064] 1 g of the etching material obtained in step 1 above was added to 50 ml of a 1 wt.%–20 wt.% tetrabutylammonium hydroxide (TBAOH) aqueous solution. After magnetic stirring (1500 r / min) for 5 min, the mixture was sonicated (1500 W) for 10 min, and then centrifuged and washed multiple times to obtain the purified sample. The stirring was performed with the rotor rotating in the same direction, providing directional flow of the liquid phase. Figure 3SEM images of samples with TBAOH added at concentrations of 1 wt.%, 5 wt.%, 10 wt.%, and 20 wt.%, respectively, are shown in ax² to d. It can be seen that when 1 wt.% TBAOH is added, the edges of the two-dimensional MXene material exhibit a curled state. Figure 3 a) Increasing the TBAOH concentration to 5 wt.% resulted in more pronounced edge curling in the two-dimensional MXene material. Figure 3 b) Further increasing the TBAOH concentration to 10 wt.%, the two-dimensional MXene material in the sample mostly exhibited a nanoroll state. Figure 3 c) When the TBAOH concentration increased to 20 wt.%, the two-dimensional MXene material in the sample was completely transformed into MXene nanorolls. Figure 3 d). Figure 3 a~d clearly demonstrate the process of MXene nanorolls gradually forming from the curling of two-dimensional MXene materials, and the one-dimensional hollow nanoroll structure formed by the curling of the edges of the same two-dimensional MXene material. Figure 4 SEM images of a sample with 20 wt.% TBAOH added but without stirring are shown. The sample exhibits a thin and flexible morphology without curling, indicating that the external force generated by directional flow is crucial for the formation of MXene nanorolls.

[0065] The above examples also demonstrate that adding an appropriate amount of positive ion-pairing reagent to the liquid phase has a significant effect on accelerating the formation of MXene nanotubes. For example, adding 20 wt.% TBAOH only requires 5 minutes of stirring and 10 minutes of sonication to obtain fully curled MXene nanotubes. In contrast, adding only 1 wt.% TBAOH, under the same conditions, can produce curling, but not the formation of nanotube structures, requiring a longer stirring time. This can be explained by the fact that a higher concentration of positive ion-pairing reagent grafts more alkyl chains onto the surface of the two-dimensional MXene material, resulting in a greater external force under the same external force, thus facilitating the rapid formation of one-dimensional hollow roll structures.

[0066] Stirring induces unidirectional flow in the liquid phase, providing a continuous and uniform external force for the rolling process, which is crucial for obtaining large quantities and uniform MXene nanorolls. Characterization results show that the two-dimensional MXene material was almost completely transformed into MXene nanorolls, as demonstrated by SEM (e.g.,...). Figure 3 d) and TEM (e.g.) Figure 6 a) As shown in the photograph, this invention enables the large-scale preparation of uniformly monodisperse MXene nanorolls, which is of great significance for subsequent applications.

[0067] In other embodiments, the positive ion pairing reagent may also be one or more of tetramethylamine hydroxide, tetraethylamine hydroxide, tetrapropylamine hydroxide, tetrabutylamine hydroxide, or tetrapentylamine hydroxide. These reagents differ from TBAOH in this embodiment in that the length of the alkyl chain is different, and it is reasonable to predict that they can produce the same technical effect.

[0068] The obtained MXene nanorolls were subjected to transmission electron microscopy (TEM) analysis, such as... Figure 5 As shown in Figure a, it can be seen that MXene nanorolls have a significant one-dimensional morphology. The length of the MXene nanorolls is between 0.5 μm and 5 μm, corresponding to the diameter of the two-dimensional MXene sheet before winding. Each MXene nanoroll is independently dispersed (monodispersed). Figure 5 b. Statistical analysis of the diameter of MXene nanotubes showed that the diameter of the nanotubes ranged from 20nm to 80nm, with the highest content of MXene nanotubes at a diameter of 40nm, accounting for more than 40%.

[0069] Figure 6 Images a and b show TEM images of MXene nanorolls at different magnifications. They clearly show that the MXene nanorolls have a hollow roll structure formed by rolling up a single sheet of two-dimensional MXene material, exhibiting a straight one-dimensional morphology, open ends, and smooth walls. Figure 6 The high-resolution electron microscopy (HRTEM) images c and d show that the walls of the MXene nanorolls consist of only 2 to 3 layers of MXene, with an interlayer spacing of 1.08 nm, meaning the wall thickness is only 3 to 4 nm. This ultra-thin wall indicates that the MXene nanorolls of this invention are formed by rolling up a single layer of MXene. Figure 6 d It can also be seen that the tube walls of MXene nanorolls show the typical hexagonal lattice of MXene, indicating that MXene nanorolls have a crystalline structure.

[0070] Figure 7 The elemental distribution of MXene nanorolls as shown by TEM analysis is presented. It can be seen that the MXene nanorolls contain V, B, C, N, O, and F elements, and these elements are uniformly distributed. O and F are functional group elements on the surface of the MXene nanorolls, and their chemical formula is V₂(B₂)₃. x C y N 1-x-y )T x match.

[0071] This invention does not limit the source of the MAX phase material; the MAX phase material can be commercially available or prepared by high-temperature sintering. For example, the MAX phase material V2AlB in this embodiment... 0.28 C 0.57 N0.15 The material is prepared by high-temperature sintering. The steps include: sintering the elemental or compound form of each element according to the stoichiometric ratio in the chemical formula of the MAX phase material at high temperature. In this embodiment, more specifically, vanadium powder (V), aluminum powder (Al), boron powder (B), carbon powder (C), and nitrogen carbonide (CN) are mixed in a molar ratio of 2:1:0.85:0.42:0.15 and ball-milled. The mixture is then placed in a high-temperature sintering furnace and sintered at 1500°C for 24 hours under an argon atmosphere, and then cooled to room temperature.

[0072] In some embodiments, the etchant in step 1 can also be replaced with hydrofluoric acid solution, or a solution of NaF + nitric acid, NaF + sulfuric acid, LiF + hydrochloric acid, or Li + nitric acid; or other etching methods, such as accordion-shaped MXene material obtained by vapor phase etching.

[0073] Example 2

[0074] This embodiment provides another MXene nanoroll with the chemical formula: V2C 0.5 N 0.5 T x The preparation methods include:

[0075] 1) Preparation of two-dimensional MXene materials from MAX phase materials

[0076] MAX phase material V2AlC 0.5 N 0.5 A mixture of concentrated hydrochloric acid (30 wt.%) and NaF, with a molar ratio of NaF to HCl of 1:1, was used for etching at 90°C for 48 hours. The resulting etched material was a two-dimensional MXene material, labeled as: V2(C x N 1-x )T x .

[0077] pass Figure 8 The XRD comparison of a shows that, compared with the MAX phase material, the (002) diffraction peak of the etched material shifts to a lower angle, and the characteristic peaks of other MAX phases disappear. This is because the A component (Al element) in the MAX phase material is selectively etched, and the interlayer spacing between its sheets increases. Figure 8 SEM images b and c show that the MAX phase material exhibits a typical layered bulk morphology. After etching, the etched material exhibits an accordion-like morphology of stacked sheets, with a significantly increased interlayer spacing, which is consistent with the previous XRD pattern results. The sheet diameter is approximately between 5 μm and 15 μm.

[0078] 2) Obtaining MXene nanorolls by rolling two-dimensional MXene materials

[0079] Add 1g of the above etching material to 50ml of a 30wt.% TBAOH aqueous solution, stir magnetically for 10min, and then centrifuge and wash several times to obtain the purified sample.

[0080] TEM test results of the sample are as follows Figure 9 As shown in a, it can be seen that the sample also exhibits a significant one-dimensional morphology. The length of the MXene nanorolls is greater than 5 μm, which corresponds to the sheet diameter of the two-dimensional MXene material before winding. This indicates that the MXene nanorolls of the present invention are obtained by rolling up two-dimensional MXene sheets. Figure 9 b. Statistical analysis of the diameter of MXene nanotubes showed that the diameter of hollow rolls ranged from 20nm to 140nm, with the highest content of MXene nanotubes at a diameter of 60nm, accounting for more than 30%.

[0081] Figure 10 The TEM image of a shows that the ports of the MXene nanorolls are open. Figure 10 b and c are HRTEM images, which show the hollow roll structure of MXene nanorolls, with approximately 3 to 6 MXene layers forming the tube walls. Figure 10 e-j shows the elemental distribution of MXene nanorolls. It can be seen that MXene nanorolls contain V, C, N, O, and F elements, and these elements are uniformly distributed. O and F are functional group elements on the surface of the MXene nanorolls, and their chemical formula is V2(C). x N 1-x )T x match.

[0082] The MAX phase material in this embodiment is prepared by high-temperature sintering. The steps include: obtaining the elemental or compound form of each element by high-temperature sintering according to the elemental stoichiometry in the chemical formula of the MAX phase material. In this embodiment, V2AlC 0.5 N 0.5 The preparation method includes: mixing vanadium powder (V), aluminum powder (Al), aluminum nitride (AlN), and carbon powder in a molar ratio of 2:0.5:0.5:0.5 and ball milling them, then placing them in a high-temperature sintering furnace and sintering them at a high temperature of 1500℃ for 24 hours under an argon atmosphere, and then cooling them to room temperature to obtain the final product.

[0083] Example 3

[0084] This embodiment provides an MXene nanoroll with the chemical formula Ti3CNT. x The preparation method includes the following steps:

[0085] 1) Preparation of two-dimensional MXene materials from MAX phase materials

[0086] The MAX phase material Ti3AlCN was etched at 90 °C for 48 h using a mixture of concentrated hydrochloric acid (30 wt.%) and LiF, wherein the molar ratio of LiF to HCl was 1:1, to obtain a two-dimensional MXene material, labeled Ti3CNT. x .

[0087] pass Figure 11 The XRD comparison of a shows that, compared with the MAX phase material, the (002) diffraction peak of the etched material shifts to a lower angle, and the characteristic peaks of other MAX phases disappear. Figure 11 SEM images b and c show that the MAX phase material exhibits a typical layered bulk morphology; the etched material exhibits an accordion-like morphology of stacked sheets, with a significantly increased interlayer spacing. The sheet diameter is approximately 3μm to 5μm.

[0088] 2) Obtaining MXene nanorolls by rolling two-dimensional MXene materials

[0089] The above-mentioned etching material was added to a 10 wt.% TBAOH aqueous solution, and after magnetic stirring for 30 min, it was centrifuged and washed multiple times to obtain a purified sample. Figure 12 Images a through c show SEM images of samples stirred for 1 min, 10 min, and 30 min, respectively. They reveal that the two-dimensional MXene material gradually curls, eventually forming MXene nanorolls with a diameter of approximately 200 nm to 300 nm. This demonstrates that the duration of external force application influences the formation of MXene nanorolls. Extending the stirring time can also yield MXene nanorolls even at lower concentrations of positive ion-paired reagents.

[0090] Example 4

[0091] This embodiment provides MXene nanorolls with the chemical formula: V2CT x Preparation methods include:

[0092] 1) The MAX phase material V2AlC was etched at 90°C for 48 hours using concentrated hydrochloric acid-NaF etchant to obtain the two-dimensional MXene material V2CT. x ;

[0093] 2) The above two-dimensional MXene material was added to a 20 wt.% TBAOH intercalating agent solution, and after magnetic stirring for 5 min, it was centrifuged, washed and purified several times, and then dried to obtain MXene nanorolls;

[0094] Figure 13 a gives V2AlC and V2CT x XRD patterns; Figure 13 b provides a SEM image of V2AlC, which shows that it is a blocky material; Figure 13 c and d give the MXene nanoroll (V2CT) x The SEM and TEM images show that MXene nanorolls have a monodisperse one-dimensional hollow nanoroll morphology, with tube diameters ranging from 40 nm to 70 nm and lengths ranging from 2 to 5 μm. Figure 13 The image provided by e shows that the wall thickness of the MXene nanorolls is between 2 nm and 3 nm, indicating that they have ultrathin walls.

[0095] Using a similar method, the applicant has also prepared other types of MXene nanorolls with the same structural characteristics, including: Ti2CT x Ti3C2T x Nb2CT x TiNbCT x Cr2CT x Ti3CNT x Ti2CT x Ti2C 0.5 N 0.5 T x Ti 0.5 V 0.5 C 0.5 N 0.5 T x V2CT x V2C 0.75 N 0.25 T x V2B 0.28 C 0.57 N 0.15 T x 、(V 0.8 Cr 0.2 )2B 0.33 C 0.67 T x 、(V 0.8 Cr 0.2 )2CT x 、(V 0.8 Fe 0.2 )2B 0.33 C 0.67 T x 、(V 0.8 Mn 0.2 )2B 0.33 C 0.67 T x 、(V 0.8 Fe 0.2 )2B 0.28 C 0.57 N 0.15 T x 、(V 0.8 Mn0.2 )2B 0.28 C 0.57 N 0.15 T x Therefore, the preparation method of the present invention has a certain degree of universality for two-dimensional MXene materials and can be prepared in large quantities. The types of MXene nanorolls prepared by the present invention are not limited to the examples given in the above embodiments. Other types of two-dimensional MXene materials can be wound to obtain the MXene nanoroll structure of the present invention by adjusting the experimental methods and conditions.

[0096] Since the MXene nanorolls of the present invention are formed by rolling up two-dimensional MXene materials, the length of the MXene nanorolls in the one-dimensional direction is related to the sheet diameter of the two-dimensional MXene materials. For two-dimensional MXene materials, the sheet diameter can be distributed between 0.1 μm and 100 μm. Therefore, we can reasonably predict that the length of the MXene nanorolls can also be within this range.

[0097] Examples 1-4 above detail the preparation method, morphology, and structural characteristics of the MXene nanorolls of the present invention. To illustrate the conductivity of the MXene nanorolls as a conductive agent, the etched material obtained in the above examples was centrifuged, washed, dispersed in a solvent using ultrasonication, and then freeze-dried to obtain two-dimensional MXene material powder. More specifically, the etched material was dispersed in water (2 mg / ml), ultrasonically treated for 12 hours, and then freeze-dried. The prepared MXene nanoroll dispersion was centrifuged, concentrated, and then freeze-dried to obtain MXene nanoroll powder. The conductivity of both powders was tested using the four-probe method. The test method was as follows: 50 mg of powder sample was added to the sample cell of a four-probe powder resistivity meter, leveled, and then the meter was turned on. The handle was rotated to move the upper probe of the resistivity meter downwards, and then the pressure was increased to 15 MPa. After the resistivity meter reading stabilized, the resistivity reading was read, and then the conductivity was obtained according to the conversion relationship of conductivity = 1 / resistivity. The results are shown in the table below.

[0098]

[0099] As can be seen, in the powder state, the MXene nanorolls of this invention have an order of magnitude higher conductivity than two-dimensional MXene materials. This is because, on the one hand, MXene nanorolls have a one-dimensional structure, resulting in better directional conductivity; on the other hand, MXene nanorolls are connected in a one-dimensional network manner, and their contact resistance is significantly lower than that of two-dimensional MXene materials, belonging to a sheet-like connection. The MXene nanorolls of this invention exhibit excellent conductivity. Using the same method, carbon nanotube powder was tested, and its conductivity was less than 100 S cm⁻¹. -1The conductivity of MXene nanotubes is significantly lower than that of the present invention. This can be explained by the fact that the conductivity of MXene materials is better than that of carbon nanotube materials. In addition, the monodisperse structure can reduce contact resistance and the linear one-dimensional structure has better electronic orientation conduction.

[0100] This invention utilizes the material and structural properties of the obtained MXene nanorolls to provide an MXene nanoroll composite material, comprising a matrix material and MXene nanorolls. The MXene nanoroll composite material can take the form of: MXene nanorolls dispersed within a matrix material; MXene nanorolls forming a coating on the surface of the matrix material; or hollow MXene nanorolls filled with matrix material, or hollow MXene nanorolls containing a filling material. The matrix material or filler can be one or more of metals, metal compounds, polymers, and inorganic non-metals. Specific embodiments are described below.

[0101] Example 5

[0102] This embodiment provides a method for implementing the composite of MXene nanorolls and inorganic non-metallic materials, specifically a composite material of MXene nanorolls and elemental sulfur (S).

[0103] One embodiment of the preparation method includes the following steps: mixing elemental sulfur with MXene nanorolls and heating the mixture to convert the elemental sulfur into a liquid state, forming a slurry in which elemental sulfur and MXene nanorolls are uniformly mixed; and cooling the slurry to obtain a composite material of elemental sulfur and MXene nanorolls. Because MXene nanorolls have nanoscale diameters, when the elemental sulfur is in a liquid state, it enters the interior of the hollow rolls through capillary adsorption, resulting in a composite material in which sulfur is filled inside the MXene nanorolls.

[0104] Another preparation method includes the following steps: thoroughly mixing elemental sulfur, MXene nanotubes, and a solvent to dissolve the elemental sulfur in the solvent, then drying to remove the solvent, resulting in a composite material in which MXene nanotubes and elemental sulfur are thoroughly and uniformly dispersed. Preferably, the composite material can be further heated to convert the elemental sulfur into a liquid state, allowing it to more fully penetrate the hollow tubes of the MXene nanotubes, resulting in a composite material in which elemental sulfur is present inside the hollow tubes of the MXene nanotubes.

[0105] In some embodiments, the mass ratio of elemental sulfur to MXene nanotubes is between 1:(0.1 to 10); preferably, it is between 1:(4 to 5) to minimize the amount of elemental sulfur outside the MXene nanotubes.

[0106] In some embodiments, the mixture or composite of MXene nanorolls and elemental sulfur is heated to a temperature between 112°C and 450°C; preferably, between 200°C and 300°C, so that the elemental sulfur rapidly forms a liquid state and enters the hollow tube.

[0107] In some embodiments, the heating time is between 0.1 h and 50 h, preferably 5 h to 10 h.

[0108] The following provides a more specific implementation method, wherein the MXene nanorolls are selected from those prepared in Example 2 (V2C). 0.5 N 0.5 T x The preparation method includes the following steps:

[0109] 1) Mix elemental sulfur and MXene nanorolls at a mass ratio of 1:4, add toluene solvent and stir for 24 hours to obtain a viscous slurry. Place the slurry in a vacuum oven and dry at 60°C to obtain a composite of MXene nanorolls and elemental sulfur.

[0110] 2) The composite from step 1 was placed in a high-temperature tube furnace and heated from room temperature to 280°C at a rate of 5°C / min under a protective gas atmosphere (argon). The temperature was held for 10 hours and then naturally cooled to obtain the MXene nanorolls@S composite material.

[0111] Figure 14 The image provided shows an SEM image of MXene nanorolls, which reveals that they exhibit a distinct one-dimensional material morphology and are monodisperse. Figure 14 b shows a SEM image of the composite of MXene nanorolls and elemental sulfur obtained in step 1 above. It can be seen that the MXene nanorolls and elemental sulfur are uniformly mixed. Figure 14 c shows the SEM image of the MXene nanorolls@S obtained in step 2 above. It can be seen that the MXene nanorolls are uniformly mixed with elemental sulfur.

[0112] The preparation method of this embodiment is applicable to inorganic non-metallic materials or compounds that can be dissolved in solvents; or inorganic non-metallic materials or compounds that can be transformed into liquids.

[0113] Example 6

[0114] This embodiment provides another method for implementing the composite of MXene nanorolls and inorganic non-metallic materials, specifically a composite material of MXene nanorolls and elemental sulfur, specifically a composite material of MXene nanorolls and silicon (Si).

[0115] One embodiment of the preparation method includes: mixing silicon, MXene nanorolls, and a binder, then adding a solvent to prepare a slurry, coating it into a film, and drying it. More specifically, the implementation steps include: mixing silicon powder, MXene nanorolls, carbon black, and polytetrafluoroethylene (PVDF) in a mass ratio of 8:0.5:0.5:1, then adding the solvent N-methylpyrrolidone (NMP) to prepare a slurry, coating it onto a copper foil to form a film, and vacuum drying it at 80°C to obtain a silicon-MXene nanoroll composite material.

[0116] Another preparation method includes: mixing silicon, MXene nanorolls, and a binder, followed by pressing to form the final product. More specifically, the steps are: mixing silicon powder, MXene nanorolls, and PVDF in a mass ratio of 7:1.5:1.5; loading the mixed powder into a powder feeder; and spraying the powder onto copper foil using a dry spraying machine. After dry spraying, the mixture is kept at 175℃ (because the melting point of PVDF is 155-160℃) and hot-pressed to obtain a composite material of silicon and MXene nanorolls.

[0117] In this embodiment, the composite material MXene nanorolls are dispersed between the matrix material (silicon), and the interior of the hollow rolls remains a hollow structure.

[0118] The preparation method of this embodiment has broad applicability and is suitable for powder materials, especially those with high melting points and difficult-to-dissolve properties or compounds; for example, silicon can be replaced with silicon oxide (SiO2), silicon suboxide (SiO), lithium iron phosphate (LiFePO4), sodium iron phosphate (NaFePO4), lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium nickel oxide (LiNiO2), or ternary materials (LiNi... x Co y Mn y O2, where x+y+z=1), Prussian blue compounds (Na x M A [M B (CN)6]·zH2O,M A and M B (e.g., transition metal ions). Of course, the present invention is not limited to this, and the composite composition can be extended to other types of metal or transition metal oxides (e.g., SnO, SnO2, VO2, V2O5, CuO, MnO2, Fe3O4, Co3O4, etc.), metal or transition metal sulfides (e.g., WS2, MoS2, etc.), etc.

[0119] Example 7

[0120] This embodiment provides a method for implementing the composite of MXene nanorolls and metal materials, specifically a composite material of MXene nanorolls and lithium metal.

[0121] One embodiment of the preparation method includes the following steps: mixing liquid metal with MXene nanoroll powder to form a slurry, and then cooling and molding to obtain a composite material, wherein the molded form can be a block or a film. More specifically, the steps include:

[0122] 1) In a glove box under an argon atmosphere, 50 mg of metallic lithium was heated to 250 °C and melted into a liquid state;

[0123] 2) Add 5 mg of MXene nanoroll powder to molten lithium metal, stir and mix to obtain a viscous slurry, coat the slurry onto a film, and cool to room temperature to obtain a composite material of MXene nanoroll and nanoroll.

[0124] Another embodiment of the preparation method includes the following steps: first, preparing MXene nanorolls into a shape, and then contacting or mixing the prepared MXene nanorolls with a liquid metal to obtain a composite material. Taking the preparation of an MXene nanoroll film as an example, the steps are illustrated through specific embodiments:

[0125] 1) The MXene nanorolls (V2B) prepared in Example 1 were used... 0.28 C 0.57 N 0.15 T x Prepared to a mass concentration of 5 mg / ml -1 The dispersion was filtered under vacuum to form a thin film on the filter membrane. The film was then vacuum dried at 60°C for 24 hours to obtain MXene nanofiber film. Figure 15 The image shows a SEM image of the MXene nanoroll film surface. It can be seen that the MXene nanorolls are a one-dimensional material and are in a monodisperse state.

[0126] 2) The MXene nanofilm is stamped into a disc with a diameter of 1.5 cm (e.g., Figure 15 b);

[0127] 3) In a glove box under an argon atmosphere, metallic lithium is heated to 250°C and melted into a liquid state;

[0128] 4) Place the disc obtained in step 2 into molten lithium metal, such as... Figure 16 As shown in Figure a, molten lithium metal appears as a bright silver liquid. The disc is initially black, but after contact with the liquid lithium metal, it is slowly soaked in, and after about several minutes, the surface of the black disc turns silver. Figure 16 b) indicates that MXene nanorolls are lithiophilic and can successfully adsorb metallic lithium.

[0129] 5) After removing the disc and cooling it to room temperature, the resulting photograph of the disc is as follows. Figure 16 As shown in c, the MXene nanoroll@lithium composite material of the present invention was obtained.

[0130] The disc containing MXene nanorolls@lithium composite material obtained above was cut into a small portion, and its surface and cross-section were analyzed by scanning electron microscopy (SEM). Figure 17 Images a through c show SEM images of the disc surface at different magnifications. It can be seen that the one-dimensional morphology of MXene nanorolls can still be clearly seen on the surface of the disc, and these one-dimensional MXene nanorolls are cross-linked and misaligned to form a cross-linked network, indicating that the adsorption of liquid lithium metal did not change the one-dimensional morphology and monodisperse characteristics of the MXene nanorolls. It can also be seen that the ports and interiors of the MXene nanorolls have obvious white color, and the white part is lithium metal. Figure 18 Images a through c are SEM images of the cross-section of the disc at different magnifications. It is clear that the MXene nanoroll@lithium composite material retains the morphology of a one-dimensional material, as shown by HRTEM images (…). Figure 19 As can be clearly seen, the hollow roll of MXene nanoroll is filled with metallic lithium, indicating that metallic lithium is absorbed inside the hollow roll of MXene nanoroll, demonstrating that MXene nanoroll can achieve metal encapsulation.

[0131] Using a similar method, in this embodiment, lithium metal can also be replaced with other types of metals or alloys, such as: one or more of alkali metals (e.g., Na, K, etc.), alkaline earth metals (e.g., Mg, Ca, etc.), transition metals (Cu, Zn, Fe, Mn, etc.); or liquid metals such as mercury (Hg) and / or gallium (Ga); to obtain composite materials of different types of MXene nanorolls and metals.

[0132] Example 8

[0133] This embodiment provides an example of MXene nanorolls composited with a polymer. Specifically, the MXene nanoroll powder of the present invention is used as a polymer modifying additive. More specifically, the MXene nanorolls (5-10 parts by weight) of the present invention are mixed evenly with polyethylene (100-120 parts), dispersant (3-5 parts), antioxidant (1-3 parts), and coupling agent (1-3 parts) in a high-speed mixer, and then extruded and granulated by a twin-screw extruder to obtain the MXene nanoroll and polyethylene composite material. Optionally, the coupling agent is isopropyl tristearate titanate, the antioxidant is antioxidant 1010, and the dispersant is sorbitan stearate.

[0134] The MXene nanorolls of this invention can also be adapted to other types of polymers, such as one or more of latex, rubber or natural rubber, polyvinyl chloride (PVC), polyethylene terephthalate (PET), polypropylene (PP), polyethylene oxide (PEO), polytetrafluoroethylene (PVDF), polyurethane (PU), polyaniline (PANI), polypyrrole (PPy), and polythiophene (PTh). The MXene nanorolls of this invention can act as functional modifying additives to improve the mechanical properties or increase the electrical conductivity of polymers.

[0135] Example 9

[0136] This embodiment provides another composite material of MXene nanorolls and polymers. Since the MXene nanorolls of the present invention are hydrophilic, they are suitable for mixing with aqueous polymer monomers or prepolymers first, and then further polymerization.

[0137] This embodiment provides a composite material of MXene nanorolls and latex, the steps of which include: mixing MXene nanorolls with a natural latex solution and then adding an initiator for polymerization.

[0138] A more specific implementation method is as follows: 0.5 to 10 parts by weight of the MXene nanofiber powder of the present invention are mixed with 100 parts of natural latex liquid and 1 to 2 parts of antioxidant. After being uniformly dispersed by stirring or ultrasonication, a vulcanizing agent is added and the temperature is raised to 60°C to 70°C to react, thereby obtaining a composite material of MXene nanofiber and latex.

[0139] Example 10

[0140] This embodiment also provides an implementation method for the composite of MXene nanorolls and metal compounds. Specifically, the MXene nanorolls of the present invention are mixed with a solution of a precursor of the metal compound (usually a metal salt), and then reacted to generate the metal compound from the precursor. This embodiment uses a composite of MXene nanorolls and iron oxide as an example.

[0141] In one specific embodiment, the steps include: mixing 10 mg of MXene nanorolls with an aqueous solution of FeCl3 (2M), placing the mixture in a hydrothermal reactor, placing it in an oven at 120°C for 24 h, and then removing it, centrifuging and washing it several times to obtain a composite of MXene nanorolls and Fe2O3.

[0142] In another specific embodiment, the steps include mixing 10 mg of MXene nanorolls with an aqueous solution of FeCl3 (2M), then adding a reducing agent (such as hydrazine hydrate) to the mixture, and after the reaction is completed, obtaining a complex of MXene nanorolls and Fe2O3.

[0143] By using a similar method to replace FeCl3 with SnCl2, SnCl4, CuCl2, etc., complexes of MXene with SnO2, SnO, CuO, etc. can also be prepared.

[0144] The preparation method of this embodiment is able to prepare a composite material with metal compounds inside the hollow roll because the metal salt can dissolve in water and the MXene nanoroll can adsorb the solution into the hollow roll through capillary action, and then react or reduce it.

[0145] Example 11

[0146] This embodiment provides an implementation method for combining MXene nanorolls with a metal compound, wherein the metal compound is lithium lanthanum zirconium oxide (Li7La3Zr2O). 12 (abbreviated as LLZO).

[0147] In one embodiment, the steps include adding MXene nanorolls to a raw material mixture, forming a lithium lanthanum zirconium oxide gel, and then sintering at high temperature; wherein the mass fraction of MXene nanorolls added to the gel can be 0.01 wt.% to 90 wt.%, preferably 3 wt.% to 20 wt.%. The specific implementation method is as follows:

[0148] 1) The raw materials required for preparing lithium lanthanum zirconium oxide, lithium nitrate, lanthanum nitrate hexahydrate, and zirconium oxynitrate hydrate were added to a nitric acid solution (16 wt.%) in an atomic ratio of Li:La:Zr = 7:3:2. Then, an excess of 10 wt.% lithium nitrate and 1.2 times the molar number of cations of complexing agent citric acid were added. After magnetic stirring until dissolved, MXene nanorolls with a mass fraction of 8 wt.% of the total gel mass were added.

[0149] 2) Stir the solution obtained in step 1 overnight to form a uniform lithium lanthanum zirconium oxide gel;

[0150] 3) The obtained lithium lanthanum zirconium oxide gel is dried in an oven, such as at 200°C for 2 hours, to obtain lithium lanthanum zirconium oxide raw powder;

[0151] 4) The lithium lanthanum zirconium oxide raw powder obtained in step 3 is sintered in a muffle furnace, such as at 900℃ for 8 hours with a heating rate of 5℃ / min. Then it is cooled with the furnace to obtain the composite powder of MXene nanorolls and lithium lanthanum zirconium oxide.

[0152] In the above embodiments, since MXene nanorolls are mixed with the mixed liquid, the hollow rolls of MXene nanorolls will also enter the solution. After high-temperature sintering, lithium lanthanum zirconium oxide will also exist inside the hollow rolls of MXene nanorolls in the resulting composite material.

[0153] In another embodiment, the steps include adding MXene nanorolls to a lithium lanthanum zirconium oxide gel and then sintering at high temperature; wherein the mass fraction of MXene nanorolls added to the gel can be 0.01 wt.% to 90 wt.%, preferably 3 wt.% to 20 wt.%. The specific implementation method is as follows:

[0154] 1) The raw materials required for the preparation of lithium lanthanum zirconium oxide, lithium nitrate, lanthanum nitrate hexahydrate, and zirconium oxynitrate hydrate were added to a nitric acid solution (16 wt.%) in an atomic ratio of Li:La:Zr = 7:3:2. Then, an excess of 10 wt.% lithium nitrate and 1.2 times the molar number of cations of complexing agent citric acid were added. The mixture was stirred magnetically until dissolved.

[0155] 2) Stir the solution obtained in step 1 overnight to form a uniform lithium lanthanum zirconium oxide gel, and then add the MXene nanoroll powder to the lithium lanthanum zirconium oxide gel and stir evenly.

[0156] 3) The lithium lanthanum zirconium oxide gel obtained in step 2 is dried in an oven, such as at 200°C for 2 hours, to obtain lithium lanthanum zirconium oxide raw powder.

[0157] 4) The lithium lanthanum zirconium oxide raw powder obtained in step 3 is sintered in a muffle furnace, such as at 900℃ for 8 hours with a heating rate of 5℃ / min. Then it is cooled with the furnace to obtain the composite powder of MXene nanorolls and lithium lanthanum zirconium oxide.

[0158] In this embodiment, since the MXene nanorolls are added to the lithium lanthanum zirconium oxide gel, and the gel has semi-solid properties, they will not enter the hollow interior of the MXene nanorolls. Therefore, in the resulting composite material, the lithium lanthanum zirconium oxide is mainly dispersed on the outside of the MXene nanorolls.

[0159] Similar methods can also be used to obtain composite materials of MXene nanorolls with materials such as lithium germanium phosphorus sulfur, lithium silicon phosphorus sulfur, and lithium phosphorus sulfur.

[0160] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. Many changes and variations can be made based on the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. An MXene nanoroll, characterized in that, The MXene nanorolls are MXene materials with a one-dimensional hollow roll structure; the chemical formula of the MXene nanorolls is M n+1 X n T x Where M is selected from one or more transition metal elements, X is selected from one, two, or three of carbon, nitrogen, or boron elements, n is 1, 2, 3, or 4, and T x For functional groups; The one-dimensional morphology of the MXene nanorolls is linear; The thickness of the tube wall of the MXene nanoroll is between 0.3 nm and 50 nm; The diameter of the MXene nanorolls ranges from 10 nm to 200 nm; The preparation method of the MXene nanorolls includes the following steps: dispersing the accordion-shaped etched material obtained by etching two-dimensional MXene material or etched MAX phase material in a liquid phase containing positive ion pairing reagent, forming liquid phase flow under the action of external force, and obtaining the MXene nanorolls.

2. The MXene nanoroll as described in claim 1, characterized in that, The transition metal element is selected from one, two, or three of the following: Ti, V, Nb, Cr, Ta, Hf, Mo, W, Fe, Mn, Y, or Sc; And / or, the functional group T of the MXene nanorolls x Includes elements of the sixth and / or seventh primary families.

3. The MXene nanoroll as described in claim 1, characterized in that, The hollow roll structure is formed by rolling up two-dimensional MXene material; And / or, the MXene nanorolls are open at both ends; And / or, the hollow roll structure is formed by rolling up a single sheet and / or a single layer of two-dimensional MXene material.

4. The MXene nanoroll as described in any one of claims 1 to 3, characterized in that, The length of the MXene nanorolls ranges from 0.1 μm to 100 μm.

5. The MXene nanoroll as described in any one of claims 1 to 3, characterized in that, The thickness of the tube wall of the MXene nanoroll is between 1 nm and 6 nm; And / or, the length of the MXene nanorolls is between 1 μm and 10 μm; And / or, the diameter of the MXene nanorolls is between 10 nm and 100 nm.

6. An aggregate of MXene nanorolls, characterized in that, The aggregate comprises: MXene nanorolls as described in any one of claims 1 to 5, wherein the MXene nanorolls are monodisperse.

7. A method for preparing MXene nanorolls as described in any one of claims 1 to 5, characterized in that, step include: An accordion-shaped etched material obtained by etching two-dimensional MXene material or MAX phase material is dispersed in a liquid phase containing a positive ion pair reagent. Under the action of external force, liquid phase flow is formed to obtain the MXene nanoroll.

8. The preparation method according to claim 7, characterized in that, The positive ion pairing reagent is an alkyl quaternary ammonium compound; And / or, the mass content of the positive ion pairing reagent in the liquid phase is between 1 wt.% and 30 wt.%. And / or, the external force is applied by: stirring, or, stirring and ultrasound; And / or, the liquid phase includes one or more of water, ethanol, and isopropanol.

9. The preparation method according to claim 8, characterized in that, The positive ion pairing reagent is selected from one or more of tetramethylamine hydroxide, tetraethylamine hydroxide, tetrapropylamine hydroxide, tetrabutylamine hydroxide, or tetrapentylamine hydroxide.

10. The preparation method according to claim 8, characterized in that, The stirring is a directional rotation.

11. An MXene nanoroll composite material, characterized in that, The MXene nanoroll composite material includes: MXene nanorolls as described in any one of claims 1 to 5; or MXene nanorolls obtained by the preparation method as described in claims 7 to 10; and, the matrix material, wherein the matrix material is selected from one or more of metals, metal compounds, polymers, and inorganic non-metals.

12. The MXene nanoroll composite material as described in claim 11, characterized in that, The hollow roll of the MXene nanoroll contains a filling material; And / or, the mass content of the MXene nanorolls is between 0.01 wt.% and 99 wt.%.

13. The MXene nanoroll composite material as described in claim 11 or 12, characterized in that, The metal is selected from one or more of alkali metals or alkaline earth metals and transition metals; or, one or more of liquid metals such as mercury, gallium, rubidium, and cesium. The metal compound is selected from one or more of the following: iron oxide, tin oxide, cobalt oxide, molybdenum oxide, molybdenum sulfide, lithium lanthanum zirconium oxide, lithium germanium phosphorus sulfide, lithium silicon phosphorus sulfide, and lithium phosphorus sulfide. The polymer is selected from one or more of the following: latex, rubber, polyvinyl chloride, polyethylene terephthalate, polypropylene, polyethylene oxide, polytetrafluoroethylene, polyurethane, polyaniline, polypyrrole, and polythiophene. The inorganic non-metal is selected from at least one of the following: sulfur, silicon, iodine, bromine, silicon oxide, and silicon suboxide.

14. A method for preparing the MXene nanoroll composite material as described in claim 11 or 12, characterized in that, The matrix material is a metal, and the steps include: converting the metal into a liquid state and then mixing or contacting it with the MXene nanorolls.

15. A method for preparing the MXene nanoroll composite material as described in claim 11 or 12, characterized in that, The matrix material is a metallic compound or an inorganic non-metal, and the steps include: The metal compound or inorganic non-metallic material powder, binder, MXene nanofibers, and solvent are mixed to form a slurry, which is then coated into a film and dried to obtain the final product. Alternatively, the metal compound or inorganic non-metal powder, binder and MXene nanorolls are mixed and then pressed into shape; Alternatively, the metal compound or the inorganic non-metal can be dissolved in a solvent, mixed with MXene nanorolls, and then dried to obtain the product.

16. A method for preparing the MXene nanoroll composite material as described in claim 11 or 12, characterized in that, The matrix material is a polymer, and the steps include: The MXene nanotubes were obtained by compounding the polymer. Alternatively, the MXene nanorolls can be mixed with the prepolymer or monomer of the polymer and then polymerized.

17. A method for preparing the MXene nanoroll composite material as described in claim 11 or 12, characterized in that, The matrix material is a metal compound, and the steps include: The MXene nanorolls were mixed with a metal salt solution and then obtained through a reduction reaction.

18. The use of MXene nanorolls as described in any one of claims 1 to 5 as a filter material, adsorbent material, sustained-release material, microwave absorbing material, catalyst carrier, electrocatalytic material, or modified material.

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