Method and use of gas-phase grown carbon-nitrogen mxene material

Abstract

The application discloses a method for growing carbon-nitrogen MXene material by a gas phase method and use, and steps of the method comprise the following: adding elemental substance and / or oxide of a transition metal, carbon nitride, and hydrogen halide gas and / or halogen element gas, heating to a reaction temperature, and then keeping the temperature for a predetermined time and cooling to obtain MXene material containing carbon and nitrogen elements. In the reaction system of the application, all the reactants except the elemental substance and / or oxide of the transition metal and the carbon nitride are gaseous products, and the carbon-nitrogen MXene material is directly synthesized by a gas phase method without a precursor MAX phase etching step, so that the production process of the carbon-nitrogen MXene material is simplified without complicated steps such as synthesizing carbon-nitrogen MAX phase and etching and cleaning.

Description

Technical Field

[0001] This invention belongs to the field of new materials, and mainly relates to a method and application of gas-phase growth of carbon-nitrogen MXene materials. Background Technology

[0002] In 2011, Gogotsi first used HF etching to obtain Ti3C2, a type of two-dimensional transition metal carbide, nitride, or carbonitride. Because of its resemblance to graphene, it was named MXene. Its chemical formula is generally denoted 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. The unique crystal properties, layered structure, high metallic conductivity, and abundant surface functional groups of MXenes make them promising candidates for applications in energy storage, electromagnetic shielding, sensing, and catalysis. The most common method for preparing MXenes is to etch the MAX phase with hydrofluoric acid (HF), although etching with a LiF+HCl system is also used. However, for carbonitride MXenes, the MA bonds in the MAX phase of the precursor are relatively strong, while the MX bonds are relatively weak, making the etching of the carbonitride MAX phase more difficult. Summary of the Invention

[0003] The purpose of this invention is, in a first aspect, to provide a novel reaction system and method for preparing carbon-nitrogen MXene materials by gas phase method. The method includes the following steps: heating a transition metal element and / or oxide, carbon nitride, and hydrogen halide gas and / or halogen element gas to a reaction temperature, holding the temperature for a predetermined time, and then cooling to obtain an MXene material, wherein the MXene material contains carbon and nitrogen elements.

[0004] In some embodiments, the transition metal is selected from one or more of the elements Ti, V, Cr, Y, Sc, Zr, Nb, Mo, Hf, Ta, and W.

[0005] In some embodiments, the hydrogen halide gas is selected from HCl, HBr, or HI.

[0006] In some embodiments, the halogen gas is selected from Cl2, Br2 or I2.

[0007] In some embodiments, the reaction temperature described above is between 650 and 1500°C; preferably, it is between 650 and 900°C.

[0008] In some embodiments, the above-mentioned heat preservation time is between 1 minute and 24 hours; preferably, it is between 30 minutes and 2 hours.

[0009] In some embodiments, the above method further includes a purification step to remove impurities from the solid product; more specifically, the purification step includes: dispersing the solid product obtained after the reaction in a non-aqueous solvent and separating it by precipitation or centrifugation.

[0010] In some embodiments, the non-aqueous solvent is 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 isopropanol (IPA).

[0011] In some embodiments, the chemical formula of the above-mentioned MXene material is M2XT. x Or M2X, where M represents a transition metal element; X represents carbon and nitrogen; T represents a functional group, wherein T includes at least one of Cl, Br, and I; 0 < x ≤2.

[0012] In some embodiments, the M in the chemical formula of the above-mentioned MXene material is selected from one or more elements selected from Ti, V, Cr, Y, Sc, Zr, Nb, Mo, Hf, Ta, and W.

[0013] A second aspect of the present invention provides an MXene material obtained by the preparation method described above.

[0014] A second aspect of the present invention provides an application of the above-mentioned MXene material in energy, catalysis, adsorption separation, sensing and detection, electromagnetic shielding, biomedicine, gas storage, microwave absorbing material, corrosion resistant material, or superconducting material.

[0015] Compared with existing technologies, in the reaction system of this invention, all reactants except for elemental transition metals and / or oxides and carbon nitride are gaseous products. This eliminates the need for a precursor MAX phase etching step, allowing direct gas-phase synthesis of carbon-nitrogen MXene materials. It also eliminates the need for complex steps such as carbon-nitrogen MAX phase synthesis, etching, and cleaning, thus simplifying the production process of carbon-nitrogen MXene materials. The method of this invention can be implemented in an open system, avoiding the tube sealing step and making the preparation process simpler; the heating reaction temperature is lower, resulting in lower energy consumption; the raw materials are more readily available; and it has promising prospects for industrial scale-up. Attached Figure Description

[0016] Figure 1 The target product MXeneTi2C in Embodiment 1 of this invention y N 1-y T x XRD pattern.

[0017] Figure 2The target product MXeneTi2C in Embodiment 1 of this invention y N 1-y T x (a) SEM image (b) TEM image (c) HRTEM and FFT image.

[0018] Figure 3 The target product MXeneTi2C in Embodiment 1 of this invention y N 1-y T x The purified XRD pattern.

[0019] Figure 4 The target product MXeneTi2C in Embodiment 1 of this invention y N 1-y T x (a) SEM image; (b) Ti element; (c) N element; (d) C element; (e) Cl element; (f) O element distribution map. Detailed Implementation

[0020] 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.

[0021] The raw materials and instruments used in the examples are not specifically limited in their source; they can be purchased from the market or prepared according to conventional methods well known to those skilled in the art. The carbon nitride (C3N4) used in this invention was prepared by laboratory personnel through thermal polymerization using melamine as a raw material. The technical features of this invention are illustrated below through specific examples.

[0022] Example 1

[0023] This embodiment provides a vapor-phase method for growing carbon-nitrogen MXene Ti2C containing chlorine (Cl) functional groups. y N 1-y T x (or written as: Ti2C) y N 1-y T x ,0< x The method involves materials of transition metal elemental titanium powder (Ti powder), C3N4, and hydrogen chloride gas, with the raw materials being: ≤2, 0<y<1. Specific preparation steps include:

[0024] Step 1) Mix Ti powder and C3N4 at a mass ratio of 8:1 and grind them thoroughly until uniform. Weigh 300mg and place it in a magnetic boat, then place it in a tube furnace and introduce argon gas into the tube furnace.

[0025] Step 2) Set the heating program of the tube furnace to increase the temperature to the reaction temperature of 750 degrees Celsius at a rate of 20°C / min, with argon gas used as a protective gas during the heating process;

[0026] Step 3) When the temperature reaches the preset temperature of 750℃, hydrogen chloride gas is introduced into the tube furnace so that the volume fraction of hydrogen chloride gas is 10%, and the temperature is maintained for 40 minutes to carry out the gas phase growth reaction.

[0027] Step 4) After holding at the temperature for 40 minutes, change the gas in the tube furnace back to argon, open the lid and air cool to room temperature, and then take out the product from the magnetic boat.

[0028] Step 5) Take out the solid product, grind it for 5 minutes, wash it with deionized water, and dry it to obtain the target product.

[0029] The product was analyzed by X-ray diffraction (XRD), and the results are as follows: Figure 1 As shown, the XRD pattern is similar to that of Ti2CCl2MXene obtained by Lewis acid molten salt etching of the Ti2AlC MAX phase, with a strong diffraction peak appearing at around 10.3 degrees, corresponding to Ti2C y N 1- y Cl x The diffraction peaks of the MXene (002) crystal plane indicate that Ti2C was successfully prepared by growth using titanium powder, C3N4, and hydrogen chloride gas. y N 1-y Cl x MXene. Additionally, cubic TiC in the heating reaction products... y N x-y These are usually byproducts, but can be effectively removed by precipitation in a non-aqueous solvent or by centrifugation to achieve product purification. Non-aqueous solvents may be one or more of the following: propylene carbonate (PC), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), acetonitrile (ACN), N,N-dimethylformamide (DMF), N-methylformamide (NMF), and isopropanol (IPA).

[0030] In this embodiment, the more specific purification steps include: [The text abruptly ends here, so the translation stops.] y N 1-y Cl xMXene was dispersed in a non-aqueous solvent DMF and sonicated. After sonication for 1 hour, the sonicated dispersion 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 then characterized. Figure 3 The purified XRD pattern and the byproduct cubic TiC are presented. y N x-y The chlorine-containing MXene is removed, yielding high-purity MXene.

[0031] The product was tested using scanning electron microscopy (SEM), and the results are as follows: Figure 2 As shown in (a), the comparison reveals that MXeneTi2C y N 1-y T x It has an accordion-like layered structure, consistent with the morphology of reported MXene.

[0032] The prepared MXene Ti2C y N 1-y T x After liquid phase exfoliation, TEM characterization was performed, and the results are as follows: Figure 2 As shown in (b), this indicates that MXene Ti2C y N 1-y T x Two-dimensional nanosheets can be obtained through simple exfoliation. Figure 2 (c) shows the HRTEM image and the diffraction spots obtained by FFT. The product exhibits a hexagonal crystal structure, consistent with the reported structure of MXene, and consistent with the XRD and SEM analysis results. EDS analysis reveals the elemental distribution of Ti, C, N, and Cl in this two-dimensional nanosheet. Figure 4 (b), (c), (d), and (e) indicate that the target product obtained is the MXene material Ti2C containing Cl functional groups. y N 1-y Cl x .

[0033] Example 2

[0034] This embodiment provides a vapor-phase method for growing carbon-nitrogen MXene Ti2C containing iodine (I) functional groups. y N 1-y T x (or written as: Ti2C) y N 1-y T x ,0< xThe method is ≤2, 0<y<1), wherein the raw materials are transition metal elemental titanium powder (Ti powder), C3N4 and iodine vapor. The specific preparation steps are similar to those in Example 1, except that hydrogen chloride gas is replaced with iodine vapor, the reaction temperature is 700℃, and the temperature is maintained for 1 hour to obtain carbon-nitrogen MXene containing iodine functional groups.

[0035] In other embodiments, a preparation method similar to that in Example 2 was used, except that iodine vapor was replaced with bromine or chlorine gas to prepare MXeneTi2C with different functional groups. m N 1-m T x (T=Br / I).

[0036] In other embodiments, a preparation method similar to that in Example 1 or 2 is used, except that the transition metal titanium powder is replaced with other transition metal powders (M), such as Nb, Zr, V, Sc, Y, Hf, Ta, and Cr powders, and the hydrogen chloride gas is replaced with hydrogen bromide or hydrogen iodide gas. This allows for the preparation of MXeneM2C with different functional groups. m N 1-m T x (T=Br / I).

[0037] Example 3

[0038] This embodiment provides a vapor-phase method for growing carbon-nitrogen MXene Ti2C containing chlorine (Cl) functional groups. y N 1-y T x (or written as: Ti2C) y N 1-y Cl x ,0< x The method is ≤2, 0<y<1), wherein the raw materials are transition metal oxide (TiO2) powder, C3N4, and hydrogen chloride gas. The specific preparation steps are similar to Example 1, except that titanium powder is replaced with titanium dioxide powder, the reaction temperature is 900℃, and the temperature is maintained for 1 hour. At high temperature, TiO2 reacts with hydrogen chloride gas to generate TiCl4, and TiCl4 reacts with C3N4 to generate MXeneTi2C. y N 1-y Cl x .

[0039] In other embodiments, titanium oxide can replace other transition metal (such as Nb, Zr, V, Sc, Y, Hf, Ta, Cr) oxide powders, and the heating reaction temperature can be adjusted between 600 and 1500 °C depending on the reactants to prepare carbon-nitrogen MXene M2CNT. xOr M2CN, where M is selected from one or more transition metal elements Ti, Nb, Zr, V, Sc, Y, Hf, Ta, and Cr, and T represents Cl, Br, or I.

[0040] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with 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. A method for growing carbon-nitrogen MXene materials by vapor phase method, characterized in that the steps include... include: The transition metal element and / or oxide, carbon nitride, and hydrogen halide gas and / or halogen element gas are heated to the reaction temperature and then cooled after holding at the temperature for a predetermined time to obtain MXene material, wherein the MXene material contains carbon and nitrogen elements.

2. The method as described in claim 1, characterized in that, The transition metal is selected from one or more of the following elements: Ti, V, Cr, Y, Sc, Zr, Nb, Mo, Hf, Ta, and W. And / or, the hydrogen halide gas is selected from HCl, HBr, or HI; And / or, the halogen gas is selected from Cl2, Br2 or I2.

3. The method as described in claim 1, characterized in that, The reaction temperature is between 650 and 1500 °C; And / or, the heat preservation time is between 1 minute and 24 hours.

4. The method as described in claim 3, characterized in that, The reaction temperature is between 650 and 900°C; And / or, the heat preservation time is between 30 minutes and 2 hours.

5. The method as described in claim 1, characterized in that, The method also includes a purification step.

6. The method as described in claim 5, characterized in that, The purification steps include: dispersing the solid product obtained after the reaction in a non-aqueous solvent, and separating it by precipitation or centrifugation.

7. The method as described in claim 6, characterized in that, 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.

8. The method according to any one of claims 1 to 7, characterized in that, The chemical formula of the MXene material is M2XT. x Or M2X, where M represents a transition metal element; X represents carbon and nitrogen; T represents a functional group, wherein T includes at least one of Cl, Br, and I; 0 < x ≤2.

9. The method as described in claim 8, characterized in that, M is selected from one or more of the elements Ti, V, Cr, Y, Sc, Zr, Nb, Mo, Hf, Ta, and W.

10. An MXene material prepared by the method described in any one of claims 1 to 9.

11. An application of the MXene material as described in claim 10 in energy, catalysis, adsorption separation, sensing and detection, electromagnetic shielding, biomedical applications for non-disease diagnosis and treatment purposes, gas storage, microwave absorbing materials, corrosion-resistant materials, or superconducting materials.

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