A MXene two-dimensional material and its preparation method and use

Abstract

The present invention discloses a MXene two-dimensional material and a preparation method and application thereof, wherein the chemical formula of the MXene two-dimensional material is expressed as M n+1 (X a Y 1‑a ) n , where M is selected from a transition metal element, X is selected from one or more of carbon, nitrogen, and boron, and Y is selected from one or more of phosphorus, oxygen, sulfur, selenium, or tellurium; 0<a<1, and n is between 1 and 4. The preparation method of this two-dimensional MXene material comprises reacting a MXene material containing a halogen element functional group with a single element, hydride, or metal salt of phosphorus, oxygen, sulfur, selenium, or tellurium. This invention produces a novel MXene material that achieves the doping of non-metallic elements at the X position, providing a new approach to multi-element manipulation of MXene materials.

Description

Technical Field

[0001] The present invention relates to the field of new material technology, and in particular to a new type of MXene two-dimensional material and its preparation method and use. Background Art

[0002] Two-dimensional transition metal carbides, nitrides or carbonitrides are also named MXene because of their two-dimensional structure similar to graphene. Their general chemical formula is M n+1 X n T x , where M is selected from transition metal elements such as Ti, Zr, V, Mo, etc., X represents C or N elements, T x Surface groups are typically -OH, -O, -F, and -Cl. A single MXene layer is approximately 1 nm thick, while its lateral dimensions can reach tens of microns or more. This unique structure and surface properties give MXene unique electrical, optical, and thermal stability properties, offering potential applications in energy storage, catalysis, adsorption, and other fields. Summary of the Invention

[0003] The object of the present invention is to provide a novel MXene material having multi-element doping at the X position.

[0004] The first aspect of the present invention provides a MXene two-dimensional material, whose chemical formula is M n+1 (X a Y 1-a ) n , wherein M is selected from one or more transition metal elements, X is selected from one or more carbon, nitrogen, and boron, and Y is selected from one or more phosphorus, oxygen, sulfur, selenium, or tellurium; 0<a<1, and n is between 1 and 4.

[0005] In some embodiments, the above-mentioned MXene two-dimensional material includes: an M layer composed of atoms of a transition metal element and an XY layer composed of atoms of X and Y, and the M layer and the XY layer are arranged alternately; and / or, the M layer and the XY layer present a hexagonal honeycomb structure; and / or, the atoms of the transition metal element occupy the central position of the octahedron.

[0006] In some embodiments, the M is selected from one or more of scandium, yttrium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten.

[0007] In some embodiments, the above-mentioned MXene two-dimensional material contains functional groups, and the functional groups are selected from one or more of phosphorus, oxygen, sulfur, selenium or tellurium elements.

[0008] In some embodiments, the above X is carbon and / or nitrogen, and its chemical formula is expressed as M n+1 (Cα N β Y 1-α-β ) n , where 0<α+β<1, 0≤α<1, 0≤β<1.

[0009] In some embodiments, the M is selected from one, two, three, four, five or six of scandium, yttrium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten.

[0010] The second aspect of the present invention also provides a method for preparing the above-mentioned MXene two-dimensional material, which comprises the following steps: reacting a MXene material containing a halogen element functional group with a single element, hydride or metal salt of phosphorus, oxygen, sulfur, selenium or tellurium.

[0011] In some embodiments, the preparation method of the above-mentioned MXene material containing halogen element functional groups includes: reacting an etchant with a MAX phase material to etch component A in the MAX phase material, wherein the etchant is selected from one or more of a halogen element, a halogen hydride, or a halogen metal salt.

[0012] In some embodiments, the halogen element is selected from Br2 or I2; the halogen hydride is selected from HCl, HBr or HI; the halogen metal salt is selected from one or more of aluminum chloride, zinc chloride, copper chloride, ferric chloride and ferrous chloride.

[0013] In some embodiments, the reaction temperature of the etchant and the MAX phase material is between 300° C. and 1800° C.; and / or the reaction time is between 1 minute and 10 hours;

[0014] In some embodiments, in the above-mentioned MXene material containing a halogen element functional group, the halogen element functional group is selected from -Cl or -I.

[0015] In some embodiments, the above-mentioned etchant is generated by thermal decomposition or sublimation of a solid; preferably, the solid includes: halogen ammonium compound, iodine element or halogen metal salt; or, the etchant is generated by vaporization of a liquid; preferably, the liquid includes: halogen acid solution, or liquefied halogen hydride or element; the compound is a halogen metal salt; or, the etchant is generated by a chemical reaction between a compound and an acid solution.

[0016] The third aspect of the present invention also provides the above-mentioned MXene two-dimensional material; or the application of the MXene two-dimensional material obtained by the above-mentioned preparation method in semiconductor electronic devices, optoelectronic devices and photocatalysis, batteries, supercapacitor materials, electromagnetic absorption and shielding materials, thermal barrier coatings or catalysts.

[0017] Existing technologies for controlling the properties of MXene materials by adding elements primarily involve high-temperature sintering of the MAX phase, the raw material for MXene, to produce a multi-element MAX phase material, which is then etched to produce the MXene material. This method typically involves adjusting the type of transition metal element at the M position in the MAX phase material to produce a MXene material containing multiple transition metal elements.

[0018] The present invention also provides a method for preparing the novel MXene material, which is obtained by reacting a MXene material containing a halogen functional group as a raw material with a single substance or compound of phosphorus, oxygen, sulfur, selenium or tellurium. The phosphorus, oxygen, sulfur, selenium or tellurium element can enter the X position of the raw material MXene to obtain a novel MXene material, realizing the doping of non-metallic elements at the X position, and providing a new idea for the multi-element regulation of MXene materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The novel MXene material M of Example 1 of the present invention n+1 (X a Y 1-a ) n Front view and top view of the atomic structure model diagram;

[0020] Figure 2 The scanning electron micrographs of the novel MXene material of Example 2 of the present invention are as follows: (a) Ti4N3Cl2, (b) Ti4(N a O 1-a )3-O2;

[0021] Figure 3 The Ti4AlN3, Ti4N3Cl2 and the new MXene material Ti4(N a O 1-a )XRD pattern of 3-O2;

[0022] Figure 4 The Ti4N3Cl2 of Example 2 of the present invention and the new MXene material Ti4(N a O 1-a )3-O2 high-resolution Ti2pXPS spectrum

[0023] Figure 5 The novel MXene material Ti4(N a O 1-a )3-O2 (a) STEM image, (b) Ti element, (c) N element and (d) O element distribution;

[0024] Figure 6This is the O K-edge XAS spectrum of Ti4N3Cl2 and the new MXene material in Example 2 of the present invention;

[0025] Figure 7 (a) Ti K-edge XAS spectrum of Ti4N3Cl2 and the new MXene material of Example 2 of the present invention, and (b) Fourier transform spectrum of the extended XAS spectrum;

[0026] Figure 8 The novel MXene material Ti3(C a S 1-a )2-S2 scanning electron microscopy image;

[0027] Figure 9 The novel MXene material Ti3(C a S 1-a ) XRD pattern of 2-S2;

[0028] Figure 10 The novel MXene material Ti3(C a S 1-a )2-S2 (a) STEM image, (b) Ti element, (c) C element and (d) S element distribution;

[0029] Figure 11 The novel MXene material Ti3(C α N β P 1-α-β )2-SEM image of P2;

[0030] Figure 12 The novel MXene material Ti3(C α N β P 1-α-β ) XRD pattern of 2-P2;

[0031] Figure 13 The novel MXene material Ti3(C α N β P 1-α-β )2-P2 (a) STEM image, (b) Ti element, (c) C element, (d) N element and (e) P element distribution diagram;

[0032] Figure 14 The novel MXene material Nb4(C a Se 1-a )SEM image of 2-Se2;

[0033] Figure 15The novel MXene material Nb4(C a Se 1-a )XRD pattern of 2-Se2;

[0034] Figure 16 The novel MXene material Nb4(C a Se 1-a )2-Se2 (a) STEM image, (b) Nb element, (c) C element and (d) Se element distribution;

[0035] Figure 17 The novel MXene material TiNb(C a Te 1-a )SEM image of 2-Te2;

[0036] Figure 18 The novel MXene material TiNb(C a Te 1-a ) XRD pattern of 2-Te2;

[0037] Figure 19 The novel MXene material TiNb(C a Te 1-a )2-Te2 (a) STEM image, (b) Ti element, (c) Nb element, (d) C element and (e) Te element distribution;

[0038] Figure 20 The novel MXene material Ti3(C a O 1-a )SEM image of 2-O2;

[0039] Figure 21 The novel MXene material Ti3(C a O 1-a )XRD pattern of 2-O2;

[0040] Figure 22 The novel MXene material Ti3(C a O 1-a )2-O2 (a) STEM image, (b) Ti element, (c) C element and (d) O element distribution diagram. DETAILED DESCRIPTION

[0041] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0042] Example 1

[0043] The chemical formula of the novel MXene material of the present invention is represented by M n+1 (X a Y 1-a ) n , Figure 1 a gives the MXene material M when n = 1 2( X a Y 1-a ), Figure 1 b shows the MXene material M3 (X a Y 1-a )2 structural diagram, Figure 1 c shows the M of MXene material when n=3 4( X a Y 1-a )3 structural diagram, from Figure 1 It can be seen that the M layer containing transition metal atoms and the XY layer of non-metal atoms in its structure present a hexagonal honeycomb structure, the n+1 layers of transition metal atoms M layer and the n layers of non-metal atoms XY layer are arranged alternately, and the transition metal atoms in the M layer occupy the central position of the octahedron, with a two-dimensional structure.

[0044] from Figure 1 It can also be seen that the new MXene material of the present invention has a better n+1 X' n The Y atom is substituted at the X' position in the MXene, thereby forming a new type of MXene material, in which the Y atom is phosphorus, oxygen, sulfur, selenium or tellurium atom.

[0045] The chemical formula of the novel MXene material of the present invention can also be expressed as: n+1 (X a Y 1-a ) n T x , where T represents the functional group on the surface of the new MXene. The new compound M can be verified by scanning electron microscope X-ray spectrometer and transmission electron microscope X-ray spectrometer. n+1 (X a Y 1-a ) n The composition of M, X and Y elements in the n+1 (X a Y 1-a ) n T x The valence states of M, X and T elements in the matrix are determined, and the positions of X, Y and T elements are determined; M n+1 (X aY 1-a ) n T x The absorption spectra of M, X and T elements in the 2D structure characterize the valence state and coordination environment of each element, and then characterize the position of M, X and T elements in the 2D structure.

[0046] Example 2

[0047] This embodiment provides a method for preparing a novel MXene material of the present invention, which is prepared by etching a MAX phase using a vapor phase method, wherein the raw material MAX phase is Ti4AlN3, comprising the following steps:

[0048] 1) Powdered Ti4AlN3 is placed inside a high-temperature reactor;

[0049] 2) introducing HCl gas into a high-temperature reactor, controlling the internal temperature of the high-temperature reactor to rise to 650° C. and maintaining the temperature for 30 minutes to obtain an intermediate product;

[0050] 3) Stop introducing HCl gas and introduce O2 gas into the high-temperature reactor. Keep the temperature at 650°C for 10 minutes. After cooling to room temperature, remove the target product.

[0051] The intermediate product and target product were analyzed by scanning electron microscope (SEM). Figure 2 As shown in Figures 2a and 2b, it can be seen that the intermediate product and the target product have obvious accordion structures, indicating that in step 2), the HCl gas achieves the etching of the MAX phase Ti4AlN3, while the continued introduction of O2 in step 3) does not change the accordion morphology characteristics of the intermediate product obtained by etching.

[0052] The raw material Ti4AlN3, intermediate product and target product were tested by X-ray diffraction (XRD). The results are as follows: Figure 3 As shown in the figure, the (002) peak in the raw material Ti4AlN3 appears at 7.4°, while the (002) peak in the target product after reacting with HCl gas shifts to a low angle of 6.0°, which indicates that HCl gas etches the Al element in Ti4AlN3 in the gas phase etching reaction, generating a lamellar structure of Ti4N3 (MXene), resulting in an increase in the interlayer spacing, which is consistent with the SEM results, indicating that the intermediate product is Ti4N3; the (002) peak in the target product is still located at 6.0°, corresponding to the (002) peak of MXene Ti4N3, which indicates that the O2 treatment does not change the crystal structure of the lamellar structure of MXene, and no phase separation occurs.

[0053] The Ti4N3T prepared by the reaction of Ti4AlN3 with HCl gas was characterized by X-ray photoelectron spectroscopy (XPS). x The surface functional groups of Figure 4 As shown, in Ti4N3T x Obvious Cl element signals were detected on the surface of the material, which corresponds to Ti4N3T x The Ti-Cl bond on the surface indicates that Cl exists in the nanosheet, indicating that the target product is a MXene material (Ti4N3-Cl2) containing Cl functional groups. After O2 treatment, the strength of the corresponding Ti-Cl bond and Ti-N bond weakened, while the strength of the Ti-O bond increased, indicating that O exists in the Ti4N3 structure, indicating that the target product is Ti4(N3-Cl2) containing O. a O 1-a )3-O2.

[0054] The transmission electron microscope (TEM) and scanning transmission electron microscope (STEM) images of the target product are as follows: Figure 5 As shown in a, there are a large number of two-dimensional ultrathin nanosheets, indicating that the accordion can be simply peeled off to obtain two-dimensional nanosheets with uniform Ti and N element distribution ( Figure 5 b and 5c), and there is also O element in the nanosheet ( Figure 5 d), indicating that the target product obtained is MXene Ti4N3 containing O.

[0055] The K-edge XAS spectrum of the O element in the target product was collected using synchrotron radiation X-ray absorption spectroscopy (XAS) technology, such as Figure 6 As shown, there is an obvious t 2g and e g Peak, compared with the product Ti4N3-Cl2 obtained by the reaction of HCl gas with Ti4AlN3, the t 2g / e g The increase in the proportion of O2 in the Ti4N3 lattice indicates that the oxygen content in the lattice increases, which can prove that the O element occupies the position of N in the Ti4N3 lattice. The target product is a new type of MXene two-dimensional material (Ti4(N a O 1-a )3-O2), its crystal structure is as follows Figure 1 As shown in c. Figure 7 As shown in a, compared with the product Ti4N3-Cl2, the absorption edge of the Ti element in the K-edge XAS spectrum of the Ti element in the MXene Ti4N3 containing O shifts toward the high energy direction, indicating that the valence state of the Ti element in the MXene Ti4N3 containing O has increased. Fourier transform spectrum of the extended XAS spectrum ( Figure 7 b) shows that the strength of Ti-N bond is significantly reduced, while the corresponding strength of Ti-O bond is increased, indicating that the O element occupies the position of N in the Ti4N3 lattice, and the target product is a new MXene Ti4(N) containing O aO 1-a )3-O2, where 0<a<1, -O2 represents the oxygen-containing functional groups on the surface of MXene.

[0056] Example 3

[0057] This embodiment provides a preparation method of a novel MXene material of the present invention, which is similar to that of embodiment 2, except that the raw material MAX phase in this embodiment is Ti3AlC2; in step 2), the temperature inside the high-temperature reactor is controlled to rise to 700°C and kept at this temperature for 30 minutes; in step 3), the O2 gas is replaced with H2S gas, and the temperature is kept at 700°C for 10 minutes, and the target product is Ti3(C2) containing S. a S 1-a )2-S2.

[0058] After the reaction device is cooled to room temperature naturally, the target product is taken out and subjected to SEM analysis. Figure 8 As shown, the target product has an accordion structure, and the target product is subjected to XRD test analysis, and the results are as follows Figure 9 As shown in the figure, the (002) peak in the target product shifts to a low angle of 7.9°, corresponding to the (002) peak of MXene Ti3C2. This indicates that the H2S treatment does not change the crystal structure of the lamellar MXene and does not produce phase separation. a S 1-a )2-S2 transmission electron microscope (TEM) and scanning transmission electron microscope (STEM) images, such as Figure 10 As shown in a, there are a large number of two-dimensional ultrathin nanosheets, indicating that the accordion can be simply peeled off to obtain two-dimensional nanosheets with uniform distribution of Ti and C elements ( Figure 10 b and 10c), and there is also S element in the nanosheet ( Figure 10 d), the target product is Ti3(C a S 1-a )2-S2, its crystal structure is as follows Figure 1 As shown in b, where 0<a<1, -S2 represents the sulfur-containing functional group on the MXene surface.

[0059] Example 4

[0060] This embodiment provides a preparation method of a novel MXene material of the present invention, which is similar to that of embodiment 2, except that the raw material MAX phase in this embodiment is Ti3AlCN; in step 2), the temperature inside the high-temperature reactor is controlled to rise to 680°C and kept at this temperature for 30 minutes; step 3) is to stop the introduction of HCl gas, introduce phosphorus vapor formed by heating and sublimating phosphorus (P) powder into the high-temperature reactor, and keep the temperature at 680°C for 10 minutes, to obtain the target product, which is a MXene material containing P, Ti3(C α N β P 1-α-β )2-P2.

[0061] After the reaction device is cooled to room temperature naturally, the target product is taken out and subjected to SEM analysis. Figure 11 As shown, the target product has an accordion structure. The target product was subjected to XRD test analysis, and the results were as follows Figure 12 As shown in the figure, the (002) peak in the target product shifts to a low angle of 8°, corresponding to the (002) peak of MXene Ti3CN. This indicates that the H2S treatment does not change the crystal structure of the lamellar MXene material and does not produce phase separation. α N β P 1-α-β )2-P2 transmission electron microscope (TEM) and scanning transmission electron microscope (STEM) images, such as Figure 13 As shown in a, there are a large number of two-dimensional ultrathin nanosheets, indicating that the accordion can be simply peeled off to obtain two-dimensional nanosheets with uniform distribution of Ti, C and N elements ( Figure 13 b, 13c and 13d), and the P element also exists in the nanosheet ( Figure 13 e), the target product is Ti3(C α N β P 1-α-β )2-P2, where 0<α+β<1, -P2 represents the phosphorus-containing functional groups on the MXene surface.

[0062] Example 5

[0063] This embodiment provides a method for preparing a novel MXene material of the present invention, wherein the raw material MAX phase is Nb4AlC3, comprising the following steps:

[0064] 1) Powdered Nb4AlC3 is placed inside a high-temperature reactor;

[0065] 2) introducing HI gas into the high-temperature reactor, controlling the temperature inside the high-temperature reactor to rise to 800° C. and maintaining the temperature for 30 minutes to obtain an intermediate product;

[0066] 3) Stop the introduction of HI gas, and introduce the selenium vapor formed by the sublimation of selenium (Se) powder into the high-temperature reactor, and keep it at 800 ° C for 10 minutes to obtain the target product, which is the MXene material Nb4 (C a Se 1-a )3-Se2.

[0067] The target product was taken out and subjected to SEM analysis, such as Figure 14 As shown in Figure 2, the target product has an accordion structure, indicating that HI gas etches the Al component in the raw material MAX phase to obtain MXene material, and Se vapor treatment does not change the accordion structure obtained by etching. The target product was tested and analyzed by XRD, and the results are shown in Figure 2. Figure 15 As shown in the figure, the (002) peak in the target product shifts to a low angle of 5.9°, corresponding to the (002) peak of MXene Nb4C3. This indicates that the Se treatment does not change the crystal structure of the lamellar MX material (MXene) and does not produce phase separation. a Se 1-a )3-Se2 transmission electron microscope (TEM) and scanning transmission electron microscope (STEM) images, such as Figure 16 As shown in a, there are a large number of two-dimensional ultrathin nanosheets, indicating that the accordion can be simply peeled off to obtain two-dimensional nanosheets with uniform distribution of Nb and C elements ( Figure 16 b and 16c), and Se element also exists in the nanosheet ( Figure 16 d), the target product is Nb4(C a Se 1-a )3-Se2, its crystal structure is as follows Figure 1 As shown in c, -Se2 represents the selenium-containing functional group on the MXene surface.

[0068] In another embodiment, the HI gas in step 2) may be replaced by iodine vapor.

[0069] Example 6

[0070] This embodiment provides a method for preparing a novel MXene material of the present invention, wherein the raw material MAX phase is TiNbAlC, comprising the following steps:

[0071] 1) Placing powdered TiNbAlC inside a high-temperature reactor;

[0072] 2) introducing HCl gas into a high-temperature reactor, controlling the temperature inside the high-temperature reactor to rise to 700° C. and maintaining the temperature for 30 minutes to obtain an intermediate product;

[0073] 3) Stop the introduction of HCl gas, and introduce the tellurium (Te) powder into the high-temperature reactor to form tellurium vapor by heating and sublimation, and keep it at 700 ° C for 10 minutes to obtain the target product, which is the MXene material TiNb (C a Te 1-a )-Te2.

[0074] The target product was analyzed by SEM. Figure 17 As shown, the target product has an accordion structure. The target product was subjected to XRD test analysis, and the results were as follows Figure 18 As shown in the figure, the (002) peak in the target product shifts to a low angle of 10°, corresponding to the (002) peak of MXene TiNbC. This indicates that the Te treatment does not change the crystal structure of the lamellar MXene and does not produce phase separation. a Te 1-a )-Te2 transmission electron microscope (TEM) scanning transmission electron microscope (STEM) image, such as Figure 19 As shown in a, there are a large number of two-dimensional ultrathin nanosheets, indicating that the accordion can be simply peeled off to obtain two-dimensional nanosheets with uniform distribution of Ti, Nb and C elements ( Figure 19 b, 19c and 19d), and the Te element also exists in the nanosheet ( Figure 19 e), the target product is the Te-containing MXene material TiNb(C a Te 1-a )-Te2, where 0<a<1, -Te2 represents the tellurium-containing functional groups on the surface of MXene.

[0075] Example 7

[0076] This embodiment provides a method for preparing a novel MXene material of the present invention, wherein the raw material MAX phase is Ti3AlC2, comprising the following steps:

[0077] 1) Powdered Ti3AlC2 and ZnCl2 are placed in different porcelain boats inside a high-temperature reactor;

[0078] 2) The temperature inside the high-temperature reactor was raised to 750°C and maintained for 1 hour, during which the ZnCl2 powder was vaporized and the MAX phase was etched to obtain the intermediate product Ti3C2-Cl2;

[0079] 3) Introduce O2 gas into the high temperature reactor, keep the temperature at 750℃ for 10min, cool to room temperature, and take out the target product Ti3(C a O 1-a )2-O2.

[0080] The target product was analyzed by SEM. Figure 20 As shown, the target product has an accordion structure. The target product was subjected to XRD test analysis, and the results were as follows Figure 21 As shown in the figure, the (002) peak in the target product shifts to a low angle of 5.8°, corresponding to the (002) peak of MXene Ti3C2. This indicates that the O2 treatment does not change the crystal structure of the lamellar MXene and does not produce phase separation. a O 1-a )2-O2 transmission electron microscope (TEM) and scanning transmission electron microscope (STEM) images, such as Figure 22 As shown in a, there are a large number of two-dimensional ultrathin nanosheets, indicating that the accordion can be simply peeled off to obtain two-dimensional nanosheets with uniform distribution of Ti and C elements ( Figure 22 b and 22c), and the Te element also exists in the nanosheet ( Figure 22 d), the target product is the MXene material Ti3(C a O 1-a )2-O2.

[0081] In other embodiments, ZnCl2 can also be replaced by other halogen metal salts, including but not limited to: one or more of aluminum chloride, zinc dichloride, copper chloride, ferric chloride, and ferrous chloride.

[0082] The above examples are merely illustrative, and the preparation method of the present invention is not limited thereto. The novel MXene structure of the present invention can be prepared by reacting a MXene containing a halogen functional group with a simple substance or hydride of the elements O, S, P, Se, and Te at a specific temperature. The specific temperature can be obtained through a limited number of experimental optimization adjustments. The specific temperature range can be 300°C to 1800°C. In the present invention, the use of -Cl and -I functional groups is preferred. These two types of functional groups can quickly achieve substitution and / or replacement of the elements O, S, P, Se, and Te at relatively low temperatures (600°C to 800°C) to obtain the novel MXene structure of the present invention.

[0083] The novel MXene materials that can be prepared by the method of the present invention include but are not limited to: Ti3(C a P 1-a )2-P2,Ti3(C a Se 1-a )2-Se2,Ti3(C a Te 1-a )2-Te2,Nb2(C a O 1-a )-O2,Nb2(C a S 1-a )-S2,Nb2(Ca Se 1-a )-Se2,Nb2(C a Te 1-a )-Te2,Nb2(C a P 1-a )-P2,Nb4(C a O 1-a )3-O2,Nb4(C a S 1-a )3-S2,Nb4(C a Te 1-a )3-Te2,Nb4(C a P 1-a )3-P2,TiNb(C a O 1-a )-O2,TiNb(C a S 1-a )-S2,TiNb(C a Se 1-a )-Se2,TiNb(C a P 1-a )-P2,Ta4(C a O 1-a )3-O2,Ta4(C a S 1-a )3-S2,Ta4(C a Se 1-a )3-Se2,Ta4(C a Te 1-a )3-Te2,Ta4(C a P 1-a )3-P2,Ta2(C a O 1-a )-O2,Ta2(C a S 1-a )-S2,Ta2(C a Se 1-a )-Se2,Ta2(C a Te 1-a )-Te2,Ta2(C a P 1-a )-P2,Ti3(C α N β O 1-α-β )3-O2,Ti3(C α N β S 1-α-β )3-S2,Ti3(C α N β Se 1-α-β )3-Se2,Ti3(C α N β Te1-α-β )3-Te2,Ti4(N a S 1-a )3-S2,Ti4(N a Se 1-a )3-Se2,Ti4(N a Te 1-a )3-Te2,Ti4(N a P 1-a )3-P2,Ti2(C a O 1-a )-O2,Ti2(C a S 1-a )-S2,Ti2(C a Se 1-a )-Se2,Ti2(C a Te 1-a )-Te2,Ti2(C a P 1-a )-P2,Ti2(N a O 1-a )-O2,Ti2(N a S 1-a )-S2,Ti2(N a Se 1-a )-Se2,Ti2(N a Te 1-a )-Te2,Ti2(N a P 1-a )-P2,Ti2(C α N β O 1-α-β )-O2,Ti2(C α N β S 1-α-β )-S2,Ti2(C α N β Se 1-α-β )-Se2,Ti2(C α N β Te 1-α-β )-Te2,Ti2(C α N β P 1-α-β )-P2。

[0084] MXene containing halogen functional groups can also be prepared by other methods, such as the molten salt method and the liquid phase etching method. In the preparation method of the present invention, a vapor phase method is used to prepare MXene with halogen functional groups. Compared with the molten salt method and the liquid phase etching method, the vapor phase method of the present invention can continuously introduce the elements or hydrides of O, S, P, Se, and Te, which greatly simplifies the preparation process, reduces the preparation cost, and can realize the industrial large-scale preparation of new MXene materials; since the vapor phase method of the present invention does not involve repeated cleaning, ultrasonication, centrifugal separation, drying and other purification steps, these steps will not cause the loss of halogen functional groups, resulting in the problem of inability to prepare.

[0085] The gas in the preparation method of the present invention can be commercial liquefied gas, or can be obtained by solid thermal decomposition, such as HCl gas obtained by heating and decomposing solid NH4Cl; or, it can be generated by chemical reaction of a compound with an acid solution, such as NaCl+H2SO4=NaHSO4+HCl↑. The present invention does not limit the source.

[0086] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for preparing MXene two-dimensional materials, characterized in that: The chemical formula of the MXene two-dimensional material is expressed as M n+1 (X a Y 1-a ) n , wherein M is selected from one or more transition metal elements, X is selected from one or more carbon, nitrogen, and boron, and Y is selected from one or more phosphorus, oxygen, sulfur, selenium, or tellurium; 0<a<1, and n is between 1 and 4; the preparation method comprises the following steps: The MXene material containing a halogen element functional group is obtained by reacting a single substance or hydride of phosphorus, oxygen, sulfur, selenium or tellurium in the gas phase; the halogen element functional group is selected from -Cl, -Br or -I.

2. The method for preparing the MXene two-dimensional material according to claim 1, wherein It includes: M layers composed of atoms of the transition metal element and XY layers composed of atoms of the X and Y elements, the M layers and the XY layers being arranged alternately; and / or, the M layer and the XY layer are in a hexagonal honeycomb structure; And / or, the atom of the transition metal element occupies the central position of the octahedron.

3. The method for preparing the MXene two-dimensional material according to claim 1, wherein The M is selected from one or more elements of scandium, yttrium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten; And / or, the MXene two-dimensional material contains functional groups, and the functional groups are selected from one or more of phosphorus, oxygen, sulfur, selenium or tellurium elements.

4. The method for preparing a MXene two-dimensional material according to any one of claims 1 to 3, wherein: The X is carbon and / or nitrogen, and its chemical formula is M n+1 (C α N β Y 1-α-β ) n , where, 0<α+β<1, 0≤α<1, 0≤β<1; And / or, the M is selected from one, two, three, four, five or six of scandium, yttrium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten.

5. The method for preparing the MXene two-dimensional material according to claim 1, wherein: A method for preparing a MXene material containing a halogen element functional group comprises: reacting an etchant with a MAX phase material to etch component A in the MAX phase material, wherein the etchant is selected from one or more of a halogen element, a halogen hydride, or a halogen metal salt.

6. The method for preparing MXene two-dimensional material according to claim 5, characterized in that: The halogen element is selected from: Br2 or I2; The halogen hydride is selected from: HCl, HBr or HI; The halogen metal salt is selected from one or more of aluminum trichloride, zinc dichloride, copper chloride, ferric chloride, and ferrous chloride.

7. The method for preparing MXene two-dimensional material according to claim 1, wherein: The reaction temperature is between 300° C. and 1800° C.; and / or the reaction time is between 1 minute and 10 hours; And / or, the halogen element functional group is selected from -Cl or -I.

8. The method for preparing MXene two-dimensional materials according to claim 7, wherein: The reaction temperature is between 600° C. and 800° C.; And / or, the reaction time is between 1 min and 10 min.

9. The method for preparing MXene two-dimensional materials according to claim 5, wherein: The etchant is generated by thermal decomposition or sublimation of a solid; Alternatively, the etchant is generated by vaporizing a liquid; Alternatively, the etchant is generated by a chemical reaction between a compound and an acid solution.

10. The preparation method according to claim 9, characterized in that The solid comprises: halogen ammonium compound, iodine element or halogen metal salt; And / or, the liquid includes: a halogen acid solution, or a liquefied halogen hydride or element; and the compound is a halogen metal salt.

11. A MXene two-dimensional material obtained by the preparation method according to any one of claims 1 to 10, characterized in that: The Y is selected from one or more of phosphorus, oxygen, sulfur, or tellurium.

12. Use of the MXene two-dimensional material according to claim 11 in semiconductor electronic devices, optoelectronic devices and photocatalysis, batteries, supercapacitor materials, electromagnetic absorption and shielding materials, thermal barrier coatings or catalysts.

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