Method for growing MXene material by vapor phase method and application

Abstract

The invention discloses a method for growing an MXene material by a vapor phase method and application, and the method comprises the following steps: heating a transition metal simple substance and / or oxide, a hydrocarbon and / or nitrogen, and a hydrogen halide gas and / or halogen simple substance gas to a reaction temperature, preserving heat for a preset time, and cooling to obtain the MXene material. The reactants in the reaction system are gaseous products except the elementary substance and / or oxide of the transition metal, a precursor MAX phase and synthesis and etching steps are not needed, the MXene material is obtained through direct gas-phase synthesis, and the production process of the MXene material is simplified.

Description

Technical Field

[0001] The present invention belongs to the field of new materials, and mainly relates to a method and application of growing MXene by a vapor phase method. Background Art

[0002] In 2011, Gogotsi first used HF to etch Ti3AlC2 to obtain Ti3C2, a type of two-dimensional transition metal carbide, nitride or carbonitride. Because it is similar to graphene, it is named MXene. Its chemical formula is generally recorded as M n+1 X n T x (M is a transition metal, including Ti, V, Cr, Y, Sc, Zr, Nb, Mo, Hf, Ta, W), X is C and (or) N, n = 1, 2 or 3, and T is a surface functional group. MXene's unique crystal properties, layered structure, high metallic conductivity and rich surface functional groups make MXene have great application prospects in energy storage, electromagnetic shielding, sensing, catalysis and other fields.

[0003] The most commonly used method for preparing MXene is to etch the MAX phase with hydrofluoric acid (HF), and there is also etching using the LiF+HCl system. Taking Ti3AlC2 as an example, 50% HF is used to etch the solution by stirring and heating at room temperature for 2 hours, and the resulting solution is diluted and filtered. The filtered sample is ultrasonically treated, and finally centrifuged at 3000r / min, and the supernatant is taken to obtain a MXene solution. The LiF+HCl system is similar to the HF system. HF is synthesized in situ in the solution to complete the etching of the A phase, and Li + The intercalation effect makes the resulting MXene easier to peel off during subsequent processing. Etching usually involves soaking the MAX material in hydrofluoric acid or other highly active solutions for up to 24 hours. This chemical removal of A atoms is very time-consuming and produces a lot of hazardous waste, while the subsequent complex process steps increase costs and environmental pollution. Summary of the invention

[0004] The purpose of the present invention is to propose a new reaction system for preparing MXene materials by a gas phase method, wherein the reactants include: transition metal elements and / or oxides, hydrocarbons and / or nitrogen, and hydrogen halide gas and / or halogen elemental gas.

[0005] The first aspect of the present invention provides a method for growing MXene by a vapor phase method, comprising the steps of heating a transition metal element and / or oxide, a hydrocarbon and / or nitrogen, and a hydrogen halide gas and / or a halogen element gas to a reaction temperature, then keeping the temperature for a predetermined time and cooling to obtain a MXene material.

[0006] In some embodiments, the transition metal is selected from one or more of Ti, V, Cr, Y, Sc, Zr, Nb, Mo, Hf, Ta, and W elements.

[0007] In some embodiments, the hydrocarbon is selected from alkanes, alkenes, and alkynes.

[0008] In some embodiments, the hydrogen halide gas is selected from HCl, HBr or HI.

[0009] In some embodiments, the halogen gas is selected from Cl2, Br2 or I2.

[0010] In some embodiments, the alkane is selected from one or more of methane, ethane, propane, and butane.

[0011] In some embodiments, the olefin is selected from one or more of ethylene, propylene, and butene.

[0012] In some embodiments, the alkyne is selected from acetylene and methylacetylene.

[0013] In some embodiments, the temperature is between 650 and 1000°C; preferably, between 650 and 850°C.

[0014] In some embodiments, the predetermined insulation time is between 1 min and 24 h; preferably, between 1 h and 2 h.

[0015] In some embodiments, the transition metal element is a transition metal element powder or a metal foil.

[0016] In some embodiments, the above method further comprises a purification step; more specifically, the purification step comprises: adding the solid product obtained after the reaction into a non-aqueous solvent for dispersion, and then precipitating or centrifuging.

[0017] In some embodiments, the non-aqueous solvent is selected from one or more of propylene carbonate, dimethyl sulfoxide, N-methylpyrrolidone, acetonitrile, N,N-dimethylformamide, N-methylformamide, and isopropanol.

[0018] In some embodiments, the chemical formula of the MXene material is M2XT x Or M2X, M represents a transition metal element; X represents carbon and / or nitrogen, T represents a functional group, and T includes: at least one of Cl, Br, I, 0<x≤2.

[0019] In some embodiments, M in the above chemical formula is selected from one or more of Ti, V, Cr, Y, Sc, Zr, Nb, Mo, Hf, Ta, and W elements.

[0020] A second aspect of the present invention provides a MXene material prepared by the above method.

[0021] A third aspect of the present invention provides an application of the above-mentioned MXene in energy, catalysis, adsorption separation, sensing detection, electromagnetic shielding, biomedicine, gas storage, absorbing materials, corrosion-resistant materials, or superconducting materials.

[0022] Compared with the prior art, in the reaction system of the present invention, all reactants except the transition metal element and / or oxide are gaseous products. No precursor MAX phase and synthesis and etching steps are required, and MXene materials can be obtained by direct gas phase synthesis, which simplifies the production process of MXene materials.

[0023] In terms of safety, the method of the present invention avoids the direct use of dangerous chemical metal halides (such as TiCl4) that are easily hydrolyzed in the air and emit white smoke. The use of hydrogen halide gas is more convenient and safer in actual use. In terms of economy, the method of the present invention can be implemented in an open system, avoiding the tube sealing step, making the preparation process simpler; the heating reaction temperature is lower (650-850°C), the energy consumption is lower; the raw materials used are easier to obtain; and it has the prospect of industrial scale-up. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The target product MXene Ti2CT in Example 1 of the present invention x XRD spectrum of .

[0025] Figure 2 MXene Ti2CCl after purification in Example 1 of the present invention x XRD pattern of .

[0026] Figure 3 The target product MXene Ti2CT in Example 1 of the present invention x (a) TEM image of

[0027] (b) HRTEM and FFT images.

[0028] Figure 4 The target product MXene Ti2CT in Example 1 of the present invention x (a) SEM photo (b) Ti element (c) C element (d) Cl element distribution diagram

[0029] Figure 5 The target product MXene Ti2NT in Example 2 of the present invention x XRD spectrum of .

[0030] Figure 6 The target product MXene Ti2NT in Example 2 of the present inventionx (a) SEM photo (b) TEM photo (c) HRTEM image.

[0031] Figure 7 The target product MXene Ti2NT in Example 2 of the present invention x (a) SEM photo (b) Ti element (c) N element (d) Cl element distribution diagram.

[0032] Figure 8 The target product MXene Ti2CT grown on titanium foil in Example 3 of the present invention x SEM photograph of.

[0033] Fig. 9 The target product MXene Ti2CT in Example 4 of the present invention x XRD spectrum of .

[0034] Fig.10 The target product MXene Ti2CT in Example 4 of the present invention x (a) SEM photo (b) TEM photo (c) HRTEM and FFT images.

[0035] Fig.11 The target product MXene Ti2CT in Example 4 of the present invention x (a) SEM photo (b) Ti element (c) C element (d) I element distribution diagram.

[0036] Fig.12 The target product MXene Ti2CT in Example 5 of the present invention x XRD spectrum of .

[0037] Fig.13 The target product MXene Ti2CT in Example 5 of the present invention x SEM image of . DETAILED DESCRIPTION

[0038] The technical solution of the present invention is described below by specific embodiments. It should be understood that one or more steps mentioned in the present invention do not exclude the existence of other methods and steps before and after the combination step, or other methods and steps can be inserted between these explicitly mentioned steps. It should also be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Unless otherwise specified, the numbering of each method step is only for the purpose of identifying each method step, and does not limit the order of arrangement of each method or limit the scope of implementation of the present invention. The change or adjustment of the relative relationship thereof can also be regarded as the scope of implementation of the present invention without substantial changes in the technical content.

[0039] The sources of the raw materials and instruments used in the examples are not particularly limited and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0040] Example 1

[0041] This embodiment provides a method for synthesizing MXene Ti2CCl by a gas phase method using metal titanium (Ti), methane gas and hydrogen chloride gas as raw materials. x The method comprises heating titanium powder, methane and hydrogen chloride gas to a reaction temperature, then keeping the temperature for a predetermined time and cooling to obtain a MXene material, wherein the reaction temperature is 650°C to 1000°C, and the holding time is 1 min to 24 h; preferably, the reaction temperature is 650°C to 850°C, and the holding time is between 1 h and 3 h. In the present embodiment, the reaction temperature is 750°C and the holding time is 1 h.

[0042] The specific preparation steps of this embodiment include:

[0043] Step 1) Grind the Ti powder thoroughly, weigh 500 mg, place it in a magnetic boat and put it into a tube furnace, introduce argon into the tube furnace, set the tube furnace heating program to heat up at 20°C / min to the reaction temperature of 750°C, and use argon as a protective gas during the heating process;

[0044] Step 2) When the temperature reaches a preset temperature of 750° C., hydrogen chloride and methane gas are introduced into the tubular furnace so that the volume fraction of hydrogen chloride gas is 10% and the volume fraction of methane gas is 5%, and the temperature is kept for 1 hour to carry out a vapor phase growth reaction;

[0045] Step 3) After the set holding time, the gas in the tube furnace was changed back to argon, the cover was opened and the furnace was air-cooled to room temperature, and the product in the magnetic boat was taken out;

[0046] Step 4) The solid product is taken out, ground for 5 minutes, washed with deionized water, and dried to obtain the target product.

[0047] The product was subjected to X-ray diffraction (XRD) analysis, and the results were as follows: Figure 1 As shown in the figure, the XRD spectrum is close to that of Ti2CCl2 MXene obtained by etching Ti2AlC MAX phase with Lewis acidic molten salt, and a strong diffraction peak appears at about 10.3 degrees, corresponding to Ti2CCl x The diffraction peak of MXene (002) crystal plane indicates that Ti2CCl was successfully prepared by growth of titanium powder, methane and hydrogen chloride gas. x MXene. From the XRD spectrum, it can be seen that the solid product contains by-product cubic TiC z(z = 0.5 ~ 1), but there is no characteristic peak of titanium powder, indicating that titanium powder is fully involved in the reaction. The by-product cubic TiC can be effectively removed by adding the solid product to a non-aqueous solvent for reprecipitation or centrifugation. z , and obtain high-purity MXene. The non-aqueous solvent can be selected from one or more of propylene carbonate (PC), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), acetonitrile (ACN), N,N-dimethylformamide (DMF), N-methylformamide (NMF), and isopropyl alcohol (IPA).

[0048] In this embodiment, the solid product was added to the non-aqueous solvent DMF and ultrasonically treated for 1 hour. The dispersion after ultrasonication was centrifuged at 3000 rpm for 5 minutes. The upper dispersion was then centrifuged at 1000 rpm for 10 minutes. The bottom product was collected, dried, and characterized. Figure 2 The XRD of the purified byproduct cubic TiC is shown. z Removed to obtain high-purity MXene Ti2CCl x .

[0049] The prepared MXene Ti2CT x After liquid phase exfoliation, TEM characterization was performed, and the results were as follows Figure 3 As shown in (a), the results show that MXene Ti2CT x Two-dimensional nanosheets can be obtained by simple exfoliation. Figure 3 (b) is the HRTEM image and its diffraction spots obtained by FFT. It can be seen that the product has a hexagonal crystal structure, which is consistent with the structure of the reported MXene and consistent with the XRD analysis results. Figure 4 (a) is the MXene Ti2CT x SEM images and EDS images of the corresponding areas ( Figure 4 (b~d)), EDS shows that the MXene Ti2CT x The distribution of Ti, C and Cl elements in the product indicates that the target product is a MXene material Ti2CCl containing Cl functional groups. x .

[0050] Example 2

[0051] This embodiment provides another method for synthesizing nitrogen-containing MXene by a gas phase method, which is similar to Example 1, except that the methane gas is replaced with nitrogen (N2), the volume percentage of nitrogen is adjusted to 20%, the volume fraction of hydrogen chloride gas is adjusted to 10%, the insulation time is 30 minutes, and the reaction temperature is adjusted to 650°C.

[0052] The product was subjected to X-ray diffraction (XRD) analysis, and the results were as follows: Figure 5 As shown, the XRD spectrum is close to that of Ti2NCl2 MXene, with a strong diffraction peak at around 10.3 degrees, corresponding to Ti2NT x The diffraction peak of MXene (002) crystal plane indicates that Ti2NT was successfully prepared by growth of titanium powder, nitrogen and hydrogen chloride gas. x MXene.

[0053] The products were tested by scanning electron microscope (SEM), and the results were as follows Figure 6 As shown in (a), by comparison, MXeneTi2NT x It has an accordion-like layered structure, which is consistent with the morphology of reported MXenes.

[0054] The prepared MXene Ti2NT x After liquid phase exfoliation, TEM characterization was performed, and the results were as follows Figure 6 As shown in (b), the results show that MXene Ti2NT x Two-dimensional nanosheets can be obtained by simple exfoliation. Figure 6 (c) is the HRTEM image, where obvious lattice fringes can be seen. Figure 7 (a) is the MXene Ti2NT x SEM images and EDS images of the corresponding areas ( Figure 7 (b~d)), EDS shows that the MXene Ti2NT x The distribution of Ti, N and Cl elements in the product indicates that the target product is a MXene material Ti2NCl containing Cl functional groups. x .

[0055] Example 3

[0056] This embodiment provides another method for synthesizing MXene by a gas phase method, which is similar to Example 1, except that the titanium powder is replaced by titanium foil, the volume fraction of methane is 20%, the reaction temperature is increased to 850°C, kept at this temperature for 1 hour, and the solid product is taken out after air cooling to room temperature.

[0057] The products were tested by scanning electron microscope (SEM), and the results were as follows Figure 8 As shown, by comparison, MXeneTi2CT x The MXenes grew in a carpet-like pattern on the titanium foil, with the MXenes sheets protruding perpendicularly to the substrate. When the holding time was further extended to 2 h, porous microspheres of MXenes were formed and eventually separated from the titanium foil substrate in the form of powder.

[0058] Example 4

[0059] This embodiment provides a vapor phase method for growing MXene Ti2CT containing iodine (I) functional groups. x (or written as: Ti2NI x , 0<x≤2) method, wherein the raw materials are transition metal single substance titanium powder (Ti powder), single substance iodine and methane gas. The specific preparation steps include:

[0060] Step 1) Grind the Ti powder thoroughly, weigh 300 mg, place it in a magnetic boat and put it in a tube furnace, weigh 1 g of iodine and place it in a magnetic boat outside the front heating area of ​​the tube furnace, and introduce argon into the tube furnace; set the tube furnace heating program to heat up at 20°C / min to a reaction temperature of 700 degrees, and use argon as a protective gas during the heating process;

[0061] Step 2) When the temperature approaches the preset temperature of 700 degrees, the heating jacket is turned on to heat the area where the iodine element is located, and the temperature is set to 750°C.

[0062] Step 3) When the temperature reaches the preset temperature of 700 degrees, methane gas is introduced into the tube furnace with a volume fraction of 5% and kept warm for 2 hours to carry out a vapor phase growth reaction. After keeping warm for 2 hours, the gas introduced into the tube furnace is changed back to argon gas, the lid is opened and air-cooled to room temperature, and the product in the magnetic boat is taken out;

[0063] Step 4) The solid product is taken out, ground for 5 minutes, washed with deionized water, and dried to obtain the target product.

[0064] The product was subjected to X-ray diffraction (XRD) analysis, and the results were as follows: Fig. 9 As shown, the XRD spectrum is close to that of Ti2CI2 MXene, with a strong diffraction peak at around 10.3 degrees, corresponding to Ti2CT x The diffraction peak of MXene (002) crystal plane indicates that Ti2NT was successfully prepared by vapor phase growth of titanium powder, nitrogen and iodine vapor. x MXene.

[0065] The products were tested by scanning electron microscope (SEM), and the results were as follows Fig.10 As shown in (a), by comparison, MXeneTi2CT x It has an accordion-like layered structure, which is consistent with the morphology of reported MXenes.

[0066] The prepared MXene Ti2CT x After liquid phase exfoliation, TEM characterization was performed, and the results were as follows Fig.10 As shown in (b), the results show that MXene Ti2CT x Two-dimensional nanosheets can be obtained by simple exfoliation. Fig.10(c) is the HRTEM image, which shows that the product has a hexagonal crystal structure, which is consistent with the structure of the reported MXene and the results of XRD and SEM analysis. Fig.11 (a) is the MXene Ti2CT x SEM images and EDS images of the corresponding areas ( Figure 7 (b~d)), the distribution of Ti, C and I elements in MXene can be seen from the EDS images ( Fig.11 (b~d)), indicating that the target product is the MXene material Ti2CI containing I functional group x .

[0067] Example 5

[0068] This embodiment provides another method for synthesizing MXene Ti2CCl by a gas phase method using titanium dioxide (TiO2), methane gas and hydrogen chloride gas as raw materials. x The preparation steps are similar to those of Example 1, except that the titanium powder is replaced by titanium dioxide powder, and the reaction temperature is above 650°C, preferably 700°C to 1000°C.

[0069] TiO2 reacts with hydrogen chloride gas and HCl gas at above 700°C to generate TiCl4. The reaction is accelerated in the temperature range of 800°C to 1000°C. In this embodiment, the reaction temperature is selected to be 850°C and kept warm for 1 hour.

[0070] The product was analyzed by X-ray diffraction (XRD), cubic TiC z (z = 0.5 ~ 1) is usually a by-product, but can be effectively removed by precipitation from the non-aqueous dispersion of the raw product. The XRD results after purification are as follows Fig.12 As shown in the XRD spectrum, a diffraction peak appears at about 6.5 degrees, corresponding to Ti2CT x The diffraction peak of MXene (002) crystal plane indicates that Ti2CT was successfully prepared by the growth of titanium dioxide, methane and hydrogen chloride gas. x MXene.

[0071] The products were tested by scanning electron microscope (SEM), and the results were as follows Fig.13 As shown, MXene Ti2CT x It has an accordion-like layered structure, which is consistent with the morphology of reported MXenes.

[0072] The methane gas in the above Examples 1 to 5 provides the carbon element in the MXene material. In other embodiments, methane can also be replaced by other gaseous alkanes, alkenes or alkynes, such as ethane, ethylene, acetylene, etc., as a carbon source for synthesizing MXene.

[0073] The hydrogen chloride gas in the above embodiments can also be replaced by HBr or HI, Cl2, Br2, I2 gas to prepare MXene materials containing Cl, Br or I.

[0074] The titanium powder, titanium foil or titanium dioxide powder in the above embodiments can also be replaced by other transition metal powders, metal foils or oxides to prepare MXene materials with different transition metal elements at the M position. In some embodiments, the transition metal element at the M position is selected from one or more of Ti, V, Cr, Y, Sc, Zr, Nb, Mo, Hf, Ta, and W elements.

[0075] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A method for growing MXene by vapor phase method, characterized in that the steps include: The transition metal element and / or oxide, hydrocarbon and / or nitrogen, and hydrogen halide gas and / or halogen element gas are heated to a reaction temperature and then kept at the temperature for a predetermined time and then cooled to obtain a MXene material.

2. The method according to claim 1, characterized in that The transition metal is selected from one or more of Ti, V, Cr, Y, Sc, Zr, Nb, Mo, Hf, Ta, and W; and / or, the hydrocarbon is selected from alkanes, alkenes, and alkynes; And / or, the hydrogen halide gas is selected from HCl, HBr or HI; And / or, the halogen elemental gas is selected from Cl2, Br2 or I2.

3. The method according to claim 2, characterized in that The alkane is selected from one or more of methane, ethane, propane and butane; And / or, the olefin is selected from one or more of ethylene, propylene and butene; And / or, the alkyne is selected from acetylene and methylacetylene.

4. The method according to any one of claims 1 to 3, characterized in that The reaction temperature is between 650°C and 1000°C; preferably, between 650°C and 850°C; And / or, the predetermined insulation time is between 1 min and 24 h; preferably, between 1 h and 2 h.

5. The method according to any one of claims 1 to 4, characterized in that The transition metal element is transition metal element powder or metal foil.

6. The method according to any one of claims 1 to 5, characterized in that The method further comprises a purification step; more specifically, the purification step comprises: adding the solid product obtained after the reaction into a non-aqueous solvent for dispersion, and then precipitating or centrifuging. Preferably, the non-aqueous solvent is selected from one or more of propylene carbonate, dimethyl sulfoxide, N-methylpyrrolidone, acetonitrile, N,N-dimethylformamide, N-methylformamide, and isopropanol.

7. The method according to any one of claims 1 to 6, characterized in that The chemical formula of the MXene material is M2XT x or M2X, M represents a transition metal element; X represents carbon and / or nitrogen, T represents a functional group, and T includes at least one of Cl, Br, and I, and 0<x≤2; Preferably, M is selected from one or more of Ti, V, Cr, Y, Sc, Zr, Nb, Mo, Hf, Ta, and W elements.

8. A MXene material prepared by the method according to any one of claims 1 to 7.

9. An application of the MXene as claimed in claim 8 in energy, catalysis, adsorption separation, sensing detection, electromagnetic shielding, biomedicine, gas storage, absorbing materials, corrosion-resistant materials, or superconducting materials.

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