WO2020114196A1

WO2020114196A1 - Mxene material, preparation method therefor and application thereof

Info

Publication number: WO2020114196A1
Application number: PCT/CN2019/116627
Authority: WO
Inventors: 黄庆; 李勉; 李友兵; 覃桂芳
Original assignee: 中国科学院宁波材料技术与工程研究所
Priority date: 2018-12-04
Filing date: 2019-11-08
Publication date: 2020-06-11

Abstract

Provided are an MXene material, a preparation method therefor and an application thereof. The molecular formula of the MXene material is expressed as M _n+1X _nY ₂, wherein M is Sc, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, or other such elements, X is an element such as C and/or N, Y is Cl, Br, I, or other such elements, and n is 1, 2, 3 or 4. The preparation method comprises: mixing a precursor MAX phase material with a transition metal chloride, a transition metal bromide, or a transition metal iodide at a molar ratio of 1:3-1:10, putting the obtained mixture in an inert atmosphere for a high-temperature reaction at 400℃-800℃ for 1-48h, then performing post treatment to obtain the MXene material. The preparation method is simple and easy, and environment friendly, and the obtained MXene material has good application in fields such as electrode materials for electrochemical energy storage, super capacitor materials, electromagnetic absorption and shielding materials, and catalysts.

Description

MXene material and its preparation method and application

Technical field

The present application relates to the technical field of two-dimensional crystal materials, in particular to an MXene material with Cl, Br, I, etc. as a surface group, and a preparation method and application thereof.

Background technique

Since the discovery of graphene in 2004, two-dimensional materials have received extensive attention and research due to their high specific surface area, high aspect ratio, and unique electronic structure. In 2011, Naguib and others reported a new type of two-dimensional material called MXene. MXene material is a type of layered two-dimensional carbon/nitride, which is usually extracted from its parent phase material MAX phase (M _n+1 AX _n , n=1-3, M is a transition metal, A is IIIA or IVA group elements, X is obtained from the atomic layer of layer A in C or N). MXene materials are better in the fields of electrode materials for electrochemical energy storage, supercapacitor materials, electromagnetic absorption and shielding materials, catalysts and other fields due to their rich composition structure controllability, unique layered structure, high conductivity and other characteristics Applications. Due to the rich elemental composition, tunability of surface functional groups, various magnetic sequences and large spin orbit coupling, in addition, there are high specific surface area, hydrophilicity, adsorption and high surface reactivity, MXenes has caused a lot of Widely concerned, such as catalysis, ion batteries, gas storage media and sensors.

In general, the preparation of MXenes is achieved by etching the MAX phase with HF acid solution. After the HF acid etched the A layer atoms of the MAX phase, the -OH, -O, and -F groups in the solution would combine with the unsaturated MX layer units to form MXene. Therefore, the surface group of the MXene material obtained by this method is inevitably composed of -OH, -O, and -F, and its component ratio is difficult to control. Many studies have pointed out that changes in the surface groups will cause changes in the electronic structure of MXene, which will have a profound impact on its electrical and magnetic properties. Theoretical predictions indicate that the MXene material whose surface groups are all composed of -O or -Cl has better chemical stability and electron transport characteristics, and its application performance in energy storage and other fields is higher than that of the MXene material whose surface group is -F . However, as of now, the currently synthesized MXene materials such as Ti ₃ C ₂ T _x , Ti ₂ CT _x , Zr ₃ C ₂ T _x , Nb ₂ CT _x , Ta ₄ C ₃ T _x , V ₂ CT _x , Ti ₄ N ₃ T _x , Mo ₂ CT _x , Hf ₃ C ₂ T _x etc., the surface groups are mostly composed of -OH, -O, -F, and the surface groups are other types (such as -Cl, -Br or -I) The MXene material has not been reported so far. MXene material has a wide range of applications in the field of battery electrodes. The MXene reported earlier with -F, -Cl, -O, etc. as the surface group is usually used as an ion storage carrier, and it cannot provide the redox reaction necessary for battery charging and discharging. . This is mainly because -F, -Cl, and -O on the surface of MXene are oxidized during charge and discharge, and a gaseous single substance is generated to escape, resulting in an irreversible charge and discharge reaction.

The environmental pollution and -F group brought by the traditional HF etching method greatly limit the application prospect of MXene materials. Therefore, developing new preparation methods to obtain MXene materials with controllable surface group types can help to adjust many functional characteristics of MXene materials, enhance their application in existing fields, and are expected to expand into new application fields.

Summary of the invention

The main purpose of the present application is to provide an MXene material and a preparation method thereof, thereby overcoming the deficiencies of the prior art.

Another main purpose of the present application is to provide the use in the MXene material.

In order to achieve the aforementioned object of the invention, the technical solutions adopted in this application include:

An embodiment of the present application provides an MXene material, and the molecular formula of the MXene material is expressed as M _n+1 X _n Y ₂ , where M is in the elements of Sc, Ti, V, Cr, Zr, Nb, Mo, Hf, and Ta Any one or a combination of two or more, X is any one or a combination of two elements C, N, Y is any one or a combination of two or more elements Cl, Br, I, n is 1, 2, 3 or 4.

The embodiments of the present application also provide a method for preparing the foregoing MXene material, which includes:

The precursor MAX phase material is combined with any one or a combination of two or more of transition metal chloride, transition metal bromide and transition metal iodide in a molar ratio of 1:3 to 1:10, and the obtained mixture Performing a high-temperature reaction at 400°C to 800°C for 1 to 48 hours in an inert atmosphere, and then performing post-treatment to obtain the MXene material;

The molecular formula of the precursor MAX phase material is expressed as M _n+1 AX _n , where M is any one or a combination of two or more elements of Sc, Ti, V, Cr, Zr, Nb, Mo, Hf, and Ta , A is selected from Group IIIA or IVA elements, X is any one or a combination of two elements of C and N, and n is 1, 2, 3 or 4.

The embodiments of the present application also provide the use of the aforementioned MXene materials in the fields of preparing electrode materials for electrochemical energy storage, supercapacitor materials, electromagnetic absorption and shielding materials, or catalysts.

Compared with the prior art, the beneficial effects of this application are:

1) The MXene material with -Cl, -Br or -I as the surface group provided in this application has better chemical and thermal stability than the traditional MXene with F as the surface group, and its electrical properties, dielectric properties, etc. have Richer controllable space, and the preparation method provided in this application is simple and easy to operate, and is environmentally friendly, avoiding many defects of the traditional preparation of MXene material by hydrofluoric acid etching. The obtained -Cl, -Br or -I is Surface group MXene materials have good applications in the fields of electrode materials for electrochemical energy storage, supercapacitor materials, electromagnetic absorption and shielding materials, catalysts, etc.;

2) Compared with the earlier reported MXene with -F, -O, etc. as the surface group, the -Cl, -Br or -I surface group obtained in this application can undergo a reversible redox reaction between MXene layers. The redox reaction process can be stably present in the liquid or solid form between the MXene layers, providing a stable reaction raw material for the battery charge and discharge reaction. This feature is not available for gas element groups such as -F and -O, so this application The obtained MXene material with -Cl, -Br or -I as the surface group can be independently used as a large-capacity, high-stability halogen battery electrode material in the field of lithium, sodium, zinc and other ion batteries.

BRIEF DESCRIPTION

In order to more clearly explain the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only These are the embodiments described in this application. For those of ordinary skill in the art, without paying any creative work, other drawings can be obtained based on these drawings.

FIG. 1 is an XRD spectrum of Ti ₃ C ₂ Cl ₂ and its precursor MAX phase Ti ₃ AlC ₂ using Cl as a surface group in Example 1 of the present application.

FIG. 2a is a scanning electron microscope image of Ti ₃ C ₂ Cl ₂ with Cl as a surface group in Example 1 of the present application.

2b is an energy spectrum analysis diagram of Ti ₃ C ₂ Cl ₂ with Cl as a surface group in Example 1 of the present application.

FIG. 3 is a high-resolution transmission electron micrograph of Ti ₃ C ₂ Cl ₂ with Cl as a surface group in Example 1 of the present application.

4 is a scanning electron micrograph of Ti ₃ C ₂ Cl ₂ with Cl as a surface group in Example 2 of the present application.

5 is a scanning electron micrograph of Ti ₃ C ₂ Cl ₂ with Cl as a surface group in Example 3 of the present application.

6 is an XRD spectrum of Ti ₂ CCl ₂ and its precursor MAX phase Ti ₃ AlC ₂ using Cl as a surface group in Example 4 of the present application.

7a is a scanning electron micrograph of Ti ₂ CCl ₂ with Cl as a surface group in Example 4 of the present application.

7b is an energy spectrum analysis diagram of Ti ₂ CCl ₂ with Cl as a surface group in Example 4 of the present application.

FIG. 8 is a high-resolution transmission electron micrograph of Ti ₂ CCl ₂ with Cl as a surface group in Example 4 of the present application.

9 is an XRD spectrum of Ti ₃ C ₂ Cl ₂ and its precursor MAX phase Ti ₃ AlC ₂ using Cl as a surface group in Example 5 of the present application.

10 is a scanning electron micrograph of Ti ₃ C ₂ Cl ₂ with Cl as a surface group in Example 5 of the present application.

11 is an XRD spectrum of Ti ₃ C ₂ Cl ₂ and its precursor MAX phase Ti ₃ SiC ₂ using Cl as a surface group in Example 6 of the present application.

12 is a scanning electron micrograph of Ti ₃ C ₂ Cl ₂ with Cl as the surface group in Example 6 of the present application.

13 is an XRD spectrum of V ₂ CCl ₂ and its precursor MAX phase V ₂ AlC using Cl as a surface group in Example 7 of the present application.

14 is a scanning electron micrograph of V ₂ CCl ₂ with Cl as a surface group in Example 7 of the present application.

15a is a scanning electron micrograph of Ti ₃ C ₂ Br ₂ with Br as a surface group in Example 8 of the present application.

15b is an energy spectrum analysis diagram of Ti ₃ C ₂ Br ₂ with Br as a surface group in Example 8 of the present application.

16 is an XRD spectrum of Ti ₃ C ₂ Br ₂ and its precursor MAX phase Ti ₃ AlC ₂ with Br as a surface group in Example 9 of the present application.

17 is a scanning electron micrograph of Ti ₃ C ₂ Br ₂ with Br as a surface group in Example 9 of the present application.

18 is an XRD spectrum of Ti ₃ C ₂ I ₂ and its precursor MAX phase Ti ₃ AlC ₂ with I as a surface group in Example 10 of the present application.

FIG. 19a is a scanning electron microscope image of Ti ₃ C ₂ I ₂ with I as the surface group in Example 10 of the present application.

FIG. 19b is an energy spectrum analysis diagram of Ti ₃ C ₂ I ₂ with I as a surface group in Example 10 of the present application.

20 is a scanning electron micrograph of Ti ₃ C ₂ Br ₂ with Br as a surface group in Example 16 of the present application.

detailed description

In view of the technical problems existing in the prior art, the inventor of this case, after long-term research and extensive practice, very unexpectedly proposed the technical solution of the present application. The technical solution, its implementation process and principle will be further explained as follows.

An aspect of an embodiment of the present application provides an MXene material whose molecular formula is expressed as M _n+1 X _n Y ₂ , where M is Sc, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, etc. Any one or a combination of two or more, X is any one or a combination of two elements C, N, Y is any one or a combination of two or more elements Cl, Br, I, n is 1, 2, 3 or 4.

In some embodiments, X may be preferably C _x N _y , where x+y=1.

In some embodiments, the crystal structure of the MXene material is composed of M _n+1 X _n units and Y atoms located on the surface of the M _n+1 X _n units, wherein the Y atoms are bonded to the M atoms.

In some more specific embodiments, the crystal structure of the MXene material is composed of M _n+1 X _n units and Cl, Br, or I atoms located on the surface of the M _n+1 X _n units, where Cl, Br, or I atom and M atom are bonded together.

In some embodiments, the form of the MXene material is a powder with a lamellar structure, the lamellar structure is composed of a single layer or multiple layers M _n+1 X _n Y ₂ (eg, M _n+1 X _n Cl ₂ , M _n+1 X _n Br ₂ or M _n+1 X _n I ₂ etc.).

Further, the lateral dimension of the sheet structure is 5 nm to 50 μm, and the thickness of the single sheet is 0.5 to 20 nm.

Another aspect of the embodiments of the present application further provides a method for preparing MXene material, including:

In some embodiments, the precursor MAX phase materials include Ti ₃ AlC ₂ , Ti ₃ SiC ₂ , Ti ₂ AlC, Ti ₂ AlN, Ti ₄ AlN ₃ , Ti ₂ GaC, V ₂ AlC, V ₂ GaC, Cr ₂ GaN, Cr ₂ AlC, Sc ₂ AlC, Zr ₂ AlC, Zr ₂ SnC, Nb ₂ AlC, Nb ₄ AlC ₃ , Mo ₂ AlC, Mo ₂ GaN, Hf ₂ AlC, Hf ₂ AlN, Ta ₃ AlC ₂ , Ta ₄ Any one or a combination of two or more of AlC _3, etc., but not limited to this.

Further, the transition metal chloride includes any one or a combination of two or more of ZnCl ₂ , CuCl ₂ , CoCl ₂ , FeCl ₂ , NiCl ₂ and the like, but is not limited thereto.

Further, the transition metal bromide includes any one or a combination of two or more of CuBr ₂ , NiBr ₂ , FeBr ₂ and ZnBr ₂ , but is not limited thereto.

Further, the transition metal iodide includes any one or a combination of two or more of CuI ₂ , NiI ₂ , FeI ₂ and ZnI ₂ , but is not limited thereto.

Further, the precursor MAX phase material is any one or a combination of two or more of powder, bulk, and thin film, but it is not limited thereto.

Further, the transition metal chloride, transition metal bromide or transition metal iodide is powder, and the particle size is 500 nm to 1 μm.

Further, the post-treatment includes: after the high-temperature reaction is completed, the elemental transition metal produced by the reaction is removed with an acid solution, and the obtained reaction product is washed with deionized water, and then at 40-60°C Dry to obtain the MXene material.

Another aspect of the embodiments of the present application also provides the aforementioned MXene material with -Cl, -Br or -I as a surface group in the preparation of electrode materials for electrochemical energy storage, supercapacitor materials, electromagnetic absorption and shielding materials or catalysts, etc. There are better uses in the field.

In summary, the chemical stability and thermal stability of the MXene material with -Cl, -Br or -I as the surface group provided in this application is better than that of the traditional MXene with surface group F, and its electrical properties and dielectric properties The performance and other have more adjustable space, and the preparation method provided in this application is simple and easy to operate, and is environmentally friendly, avoiding many defects of the traditional preparation of MXene material by hydrofluoric acid etching. The obtained -Cl, -Br or The MXene material with I as the surface group has good applications in the fields of electrode materials for electrochemical energy storage, supercapacitor materials, electromagnetic absorption and shielding materials, catalysts, etc.

Compared with the earlier reported MXene with -F, -O, etc. as the surface group, the -Cl, -Br or -I surface group obtained in this application can undergo a reversible redox reaction between the MXene layers. It can be stably present in the liquid or solid form between the MXene layers during the reaction process, providing stable reaction raw materials for battery charge and discharge reactions. This feature is not available for gas element groups such as -F and -O. The MXene material with -Cl, -Br or -I as the surface group can be independently used as a large-capacity, high-stability halogen battery electrode material in the field of lithium, sodium, zinc and other ion batteries.

In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be further explained in detail in conjunction with the accompanying drawings and several preferred embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as there is no conflict with each other.

Example 1

In this example, the MXene material with Cl as the surface group is Ti ₃ C ₂ Cl ₂ , the precursor MAX phase is Ti ₃ AlC ₂ , and the transition metal chloride is ZnCl _2. These raw materials can be obtained through commercial sales and other methods. . The preparation method of the Ti ₃ C ₂ Cl ₂ is as follows:

(1) Weigh 0.15 mol of ZnCl _{2 with a} particle size of 500 nm and 0.05 mol of Ti ₃ AlC ₂ powder with a particle size of 10 μm, and grind and mix the above materials to obtain a mixed product.

(2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. The reaction conditions are: 400°C, 48 hours, protected by argon. After the tube furnace temperature was lowered to room temperature, the reaction product in the crucible was taken out.

(3) Wash the reaction product with deionized water: put the reaction product in a beaker, add deionized water, stir and ultrasonically clean for 30 minutes, then stand for 1 hour, and pour off the supernatant. After washing the reaction product three times, it was placed in an oven at 40°C and taken out after 24 hours to obtain a solid product.

(4) Place the above solid product in 20 mL of dilute hydrochloric acid with a mass fraction of 10%, soak for 2 hours, and remove the Zn elemental substance therein to obtain Ti ₃ C ₂ Cl ₂ .

The precursor of FIG. 1 is that the MAX phase is Ti ₃ AlC ₂ , and the XRD patterns of the products obtained in Step 3 and Step 4 are compared. It can be seen from the comparison that after the reaction in step 3, the intensity of the diffraction peaks (104), (105), (110) and other products of the product is significantly weakened, indicating that the order of the product along the crystal plane decreases; (002), ( Diffraction peaks such as 004) and (006) shifted obviously to low angles, and the corresponding cell parameter c value increased to 22.10 nm, which was higher than the c value of Ti ₃ AlC ₂ 18.48 nm. The changes in the XRD pattern above are consistent with the changes in the preparation of Ti ₃ C ₂ MXene using HF etching of Ti ₃ AlC ₂ , indicating that the Al atoms located between the Ti ₃ AlC ₂ layers are extracted and new atoms are embedded. In addition, a significant diffraction peak of elemental Zn was detected in the product, which was caused by a chemical reaction between ZnCl ₂ and Al atoms in Ti ₃ AlC _2. After immersion in hydrochloric acid, the diffraction peak of elemental Zn disappeared, resulting in high purity Ti ₃ C ₂ Cl ₂ MXene.

Figure 2a is a scanning electron microscope image of the product Ti ₃ C ₂ Cl ₂ MXene in Step 4. It can be seen that it exhibits a distinct “accordion” morphology characteristic of the MXene material because of the Al located between the Ti ₃ C ₂ layers The atoms are pulled away, and the newly embedded Cl atoms cause the bonding between the Ti ₃ C ₂ Cl ₂ layers to weaken and the interlayer spacing to increase, thereby exhibiting a multilayer structure. Figure 2b is the energy spectrum analysis of Figure 2a. It can be seen that the main element composition is Ti:C:Cl=36.3:27.8:24.1, which is close to the ratio of 3:2:2. In addition, there is a small amount of O element in the product. It was introduced during product washing.

Fig. 3 confirms the atomic arrangement of the Ti ₃ C ₂ Cl ₂ product in Step 4 by high-resolution transmission electron microscopy. From this figure, it can be clearly seen that the Cl atoms bound to the Ti ₃ C ₂ layer strongly confirm the product It is Ti ₃ C ₂ Cl ₂ .

Example 2

(1) Weigh 0.3 mol of ZnCl _{2 with a} particle size of 800 nm and 0.05 mol of Ti ₃ AlC ₂ powder with a particle size of 10 μm, and grind and mix the above materials to obtain a mixed product.

(2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. The reaction conditions are: 600°C, 24 hours, argon protection. After the tube furnace temperature was lowered to room temperature, the reaction product in the crucible was taken out.

Fig. 4 is a scanning electron microscope image of the product Ti ₃ C ₂ Cl ₂ MXene in Step 4. It can be seen that it shows a distinct “accordion” morphology characteristic of the MXene material because of the Al located between Ti ₃ C ₂ layers The atoms are pulled away, and the newly embedded Cl atoms cause the bonding between the Ti ₃ C ₂ Cl ₂ layers to weaken and the interlayer spacing to increase, thereby exhibiting a multilayer structure.

Example 3

(1) Weigh 0.5 mol of ZnCl _{2 with a} particle size of 600 nm and 0.05 mol of Ti ₃ AlC ₂ powder with a particle size of 10 μm, and grind and mix the above materials to obtain a mixed product.

(2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. The reaction conditions were: 800°C, 1 hour, protected by argon. After the tube furnace temperature was lowered to room temperature, the reaction product in the crucible was taken out.

(3) Wash the reaction product with deionized water: put the reaction product in a beaker, add deionized water, stir and ultrasonically clean for 30 minutes, then stand for 1 hour, and pour off the supernatant. After washing the reaction product three times, it was placed in an oven at 60°C and taken out after 24 hours to obtain a solid product.

Fig. 5 is a scanning electron microscope image of the product Ti ₃ C ₂ Cl ₂ MXene in Step 4. It can be seen that it exhibits an obvious “accordion” morphology structure unique to MXene material, because of the Al located between Ti ₃ C ₂ layers. The atoms are pulled away, and the newly embedded Cl atoms cause the bonding between the Ti ₃ C ₂ Cl ₂ layers to weaken and the interlayer spacing to increase, thereby exhibiting a multilayer structure.

Example 4

In this embodiment, the MXene material with Cl as the surface group is Ti ₂ CCl ₂ , the precursor MAX phase is Ti ₂ AlC, and the transition metal chloride is ZnCl _2. These raw materials can be obtained through commercial sales. The preparation method of the Ti ₂ CCl ₂ is as follows:

(1) Weigh 0.5 mol of ZnCl _{2 with a} particle size of 1 μm and 0.05 mol of Ti ₂ AlC powder with a particle size of 10 μm, and grind and mix the above materials to obtain a mixed product.

(2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. The reaction conditions were: 550°C, 3 hours, argon protection. After the tube furnace temperature was lowered to room temperature, the reaction product in the crucible was taken out.

(4) Put the above solid product in 20 mL of dilute hydrochloric acid with a mass fraction of 5% and soak for 2 hours to remove the Zn elemental substance to obtain Ti ₂ CCl ₂ .

The precursor of FIG. 6 is that the MAX phase is Ti ₂ AlC, and the XRD patterns of the products obtained in Step 3 and Step 4 are compared. It can be seen from the comparison: after the reaction in step 3, the intensity of the diffraction peaks such as (103), (106), (110) of the product is significantly weakened, indicating that the order of the product along the crystal plane decreases; (002), ( Diffraction peaks such as 004) and (006) shifted to a low angle, and the corresponding cell parameter c value increased to 17.24 nm, which was higher than the Ti ₂ AlC c value of 13.52 nm. The above XRD pattern changes indicate that Al atoms located between the Ti ₂ AlC layers are extracted and new atoms are inserted. In addition, a significant diffraction peak of elemental Zn was detected in the product, which was caused by a chemical reaction between ZnCl ₂ and Al atoms in Ti ₂ AlC. After immersion in hydrochloric acid, the diffraction peak of elemental Zn disappeared, and Ti ₂ CCl ₂ MXene . In addition, there is a small amount of TiC impurities in the product, which is present in the precursor Ti ₂ AlC.

Figure 7a is a scanning electron microscope image of the product Ti ₂ CCl ₂ MXene in Step 4. It can be seen that it exhibits a distinct “accordion” morphology characteristic of the MXene material, because Al atoms located between the Ti ₂ C layers are extracted As a result, newly inserted Cl atoms cause the bonding between Ti ₂ CCl ₂ layers to weaken and the interlayer spacing to increase, thus exhibiting a multilayer structure. Figure 7b is the energy spectrum analysis of Figure 7a. It can be seen that the main element composition is Ti:C:Cl=31.3:23.8:33.7, which is close to the ratio of 2:1:2. In addition, there is a small amount of O element in the product. It was introduced during product washing.

Fig. 8 confirms the atomic arrangement of the Ti ₂ CCl ₂ product in Step 4 by high-resolution transmission electron microscopy. From this figure, it can be clearly seen that the Cl atoms bound to the Ti ₂ C layer confirm that the product is Ti ₂ CCl ₂ .

Example 5

In this example, the MXene material with Cl as the surface group is Ti ₃ C ₂ Cl ₂ , the precursor MAX phase is Ti ₃ AlC ₂ , and the transition metal chloride is FeCl _2. These raw materials can be obtained through commercially available methods. . The preparation method of the Ti ₃ C ₂ Cl ₂ is as follows:

(1) Weigh 0.3 mol of FeCl _{2 with a} particle size of 700 nm and 0.05 mol of Ti ₃ AlC ₂ powder with a particle size of 10 μm, and grind and mix the above materials to obtain a mixed product.

(2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. The reaction conditions were: 650°C, 5 hours, protected by argon. After the tube furnace temperature was lowered to room temperature, the reaction product in the crucible was taken out.

(3) Wash the reaction product with deionized water: put the reaction product in a beaker, add deionized water, stir and ultrasonically clean for 30 minutes, then stand for 1 hour, and pour off the supernatant. After washing the reaction product three times, it was placed in an oven at 50°C and taken out after 24 hours to obtain a solid product.

(4) Place the above solid product in 20 mL of dilute hydrochloric acid with a mass fraction of 10%, soak for 10 h, and remove the Fe elemental substance therein to obtain Ti ₃ C ₂ Cl ₂ .

The precursor of FIG. 9 is that the MAX phase is Ti ₃ AlC ₂ , and the XRD patterns of the products obtained in Step 3 and Step 4 are compared. It can be seen from the comparison that after the reaction in step 3, the intensity of the diffraction peaks (104), (105), (110) and other products of the product is significantly weakened, indicating that the order of the product along the crystal plane decreases; (002), ( Diffraction peaks such as 004) and (006) shifted significantly to low angles. The above XRD pattern changes indicate that Al atoms located between the Ti ₃ AlC ₂ layers are extracted and new atoms are inserted. In addition, a significant diffraction peak of elemental Fe was detected in the product. This is due to the chemical reaction between FeCl ₂ and the Al atoms in Ti ₃ AlC _2. After immersion in hydrochloric acid, the diffraction peak of elemental Fe disappeared and high purity Ti was obtained. ₃ C ₂ Cl ₂ MXene.

Fig. 10 is a scanning electron microscope image of the product Ti ₃ C ₂ Cl ₂ MXene in Step 4. It can be seen that it exhibits an obvious “accordion” morphology characteristic of the MXene material. This is due to the Al located between Ti ₃ C ₂ layers. The atoms are pulled away, and the newly embedded Cl atoms cause the bonding between the Ti ₃ C ₂ Cl ₂ layers to weaken and the interlayer spacing to increase, thereby exhibiting a multilayer structure.

Example 6

In this example, the MXene material with Cl as the surface group is Ti ₃ C ₂ Cl ₂ , the precursor MAX phase is Ti ₃ SiC ₂ , and the transition metal chloride is CuCl _2. These raw materials can be obtained through commercially available channels. . The preparation method of the Ti ₃ C ₂ Cl ₂ is as follows:

(1) Weigh 0.3 mol of CuCl ₂ and 0.5 mol of Ti ₃ AlC ₂ powder with a particle size of 10 μm, and grind and mix the above materials to obtain a mixed product.

(2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. The reaction conditions were: 750°C, 6 hours, protected by argon. After the tube furnace temperature was lowered to room temperature, the reaction product in the crucible was taken out.

(4) Place the above solid product in 20 mL of dilute nitric acid with a mass fraction of 10%, soak for 10 h, and remove the Cu element in it to obtain Ti ₃ C ₂ Cl ₂ .

The precursor of FIG. 11 is that the MAX phase is Ti ₃ SiC ₂ , and the XRD patterns of the products obtained in Step 3 and Step 4 are compared. It can be seen from the comparison that after the reaction in step 3, the intensity of the diffraction peaks (104), (105), (110) and other products of the product is significantly weakened, indicating that the order of the product along the crystal plane decreases; (002), ( Diffraction peaks such as 004) and (006) shifted significantly to low angles. The above XRD pattern changes indicate that Si atoms located between the Ti ₃ SiC ₂ layers are extracted and new atoms are inserted. In addition, a significant Cu element diffraction peak was detected in the product. This was due to the chemical reaction between CuCl ₂ and the Al atoms in Ti ₃ SiC _2. After soaking with nitric acid, the Cu element diffraction peak disappeared, resulting in high purity Ti ₃ C ₂ Cl ₂ MXene.

Fig. 12 is a scanning electron microscope image of the product Ti ₃ C ₂ Cl ₂ MXene in Step 4. It can be seen that it exhibits an obvious “accordion” morphology structure unique to MXene material, which is due to the Si located between Ti ₃ C ₂ layers. The atoms are pulled away, and the newly embedded Cl atoms cause the bonding between the Ti ₃ C ₂ Cl ₂ layers to weaken and the interlayer spacing to increase, thereby exhibiting a multilayer structure.

Example 7

In this embodiment, the MXene material with Cl as the surface group is V ₂ CCl ₂ , the precursor MAX phase is V ₂ AlC, and the transition metal chloride is CuCl _2. These raw materials can all be obtained through commercial sales. The preparation method of the V ₂ CCl ₂ is as follows:

(1) Weigh 0.5 mol of CuCl _{2 with a} particle size of 1 μm and 0.05 mol of V ₂ AlC powder with a particle size of 10 μm, and grind and mix the above materials to obtain a mixed product.

(2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. The reaction conditions are: 750°C, 12 hours, protected by argon. After the tube furnace temperature was lowered to room temperature, the reaction product in the crucible was taken out.

Fig. 13 is a comparison of XRD patterns of the precursor obtained by the MAX phase being V ₂ AlC and the product obtained in step 4. It can be seen from the comparison that after the reaction in step 3, the intensity of the diffraction peaks of (103), (106), (110) and other products of the product is significantly weakened, indicating that the order of the product along the crystal plane decreases; and (103), (002) The iso-diffraction peak is obviously shifted to a low angle, and the corresponding interplanar spacing is increased. The above XRD pattern changes are caused by the increase of unit cell parameters due to the extraction of Al atoms between the V ₂ AlC layers and the insertion of Cl atoms. In addition, it is worth noting that part of the V ₂ AlC remains in the reaction product. This is due to the strong V-Al bonding in V ₂ AlC and the fact that Al atoms are not easily extracted.

Fig. 14 is a scanning electron microscope image of the product V ₂ CCl ₂ MXene in Step 4. It can be seen that it exhibits a distinct “accordion” morphology characteristic of the MXene material, because Al atoms located between the V ₂ AlC layers are extracted The newly inserted Cl atoms cause the bonding between the V ₂ CCl ₂ layers to weaken and the interlayer spacing to increase, thus exhibiting a multilayer structure.

In addition, the inventors of this case also carried out related experiments by replacing the corresponding raw materials and process conditions in the foregoing Examples 1-7 with other raw materials and process conditions mentioned in this specification. The results all show that MXene with Cl as the surface group can be obtained material.

In summary, compared with existing materials, the preparation method of the MXene material with Cl as a surface group provided in the foregoing examples of the present application is simple and easy to implement, and is environmentally friendly, avoiding many traditional preparations of MXene materials by hydrofluoric acid etching Defects, the obtained MXene material with Cl as a surface group has good applications in the fields of electrode materials for electrochemical energy storage, supercapacitor materials, electromagnetic absorption and shielding materials, catalysts, etc.

Example 8

In this example, the MXene material with Br as the surface group is Ti ₃ C ₂ Br ₂ , the precursor MAX phase is Ti ₃ AlC ₂ , and the transition metal chloride is CuBr _2. These raw materials can be obtained through commercially available methods. . The preparation method of the Ti ₃ C ₂ Br ₂ is as follows:

(1) Weigh 0.15 mol of CuBr _{2 and} 0.05 mol of Ti ₃ AlC ₂ powder with a particle size of 10 μm, and grind and mix the above materials to obtain a mixed product.

(2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. The reaction conditions were: 700°C, 7 hours, argon protection. After the tube furnace temperature was lowered to room temperature, the reaction product in the crucible was taken out.

(4) Place the above solid product in 20 mL of APS solution with a molar fraction of 1 mol/L prepared in advance, and soak for 2 h to remove the Cu element in it to obtain Ti ₃ C ₂ Br ₂ .

Fig. 15a is a scanning electron microscope image of the product Ti ₃ C ₂ Br ₂ MXene material obtained in this example. It can be seen that it exhibits a distinct "accordion" morphology structure unique to MXene material, because it is located in Ti ₃ C ₂ The Al atoms between the layers are detached, and the newly inserted Br atoms cause the bonding between the Ti ₃ C ₂ Br ₂ layers to weaken and the interlayer distance to increase, thereby exhibiting a multilayer structure. Figure 15b is the energy spectrum analysis of Figure 15a. It can be seen that the main element composition is Ti:Br=30.8:22.42, which is close to 3:2. In addition, there is a small amount of O element in the product, which is introduced during the product washing process. Yes, a small amount of Cu is produced by the reduction of Cu ²⁺ during the reaction.

Example 9

In this example, the MXene material with Br as the surface group is Ti ₃ C ₂ Br ₂ , the precursor MAX phase is Ti ₃ AlC ₂ , and the transition metal chloride is NiBr _2. These raw materials can be obtained through commercial sales and other methods. . The preparation method of the Ti ₃ C ₂ Br ₂ is as follows:

(1) Weigh 0.75 mol of NiBr _{2 and} 0.05 mol of Ti ₃ AlC ₂ powder with a particle size of 10 μm, and grind and mix the above materials to obtain a mixed product.

(4) Put the above solid product in 20 mL of dilute hydrochloric acid with a mass fraction of 10%, soak for 2 h, and remove the elemental Ni in it to obtain Ti ₃ C ₂ Br ₂ .

The precursor of FIG. 16 is that the MAX phase is Ti ₃ AlC ₂ , and the XRD patterns of the products obtained in Step 3 and Step 4 are compared. It can be seen from the comparison that after the reaction in step 3, the intensity of the diffraction peaks (104), (105), (110) and other products of the product is significantly weakened, indicating that the order of the product along the crystal plane decreases; (002), ( Diffraction peaks such as 004) and (006) shifted to a low angle, and the corresponding cell parameter c value increased to 23.96 nm, which was higher than the c value of Ti ₃ AlC ₂ 18.48 nm. The changes in the XRD pattern above are consistent with the changes in the preparation of Ti ₃ C ₂ MXene using HF etching of Ti ₃ AlC ₂ , indicating that the Al atoms located between the Ti ₃ AlC ₂ layers are extracted and new atoms are embedded. In addition, a significant AlNi alloy diffraction peak was detected in the product. This is due to the chemical reaction between NiBr ₂ and the Al atoms in Ti ₃ AlC _2. After immersion in hydrochloric acid, the diffraction peak of the AlNi alloy disappeared, resulting in high purity Ti ₃ C ₂ B _r2 MXene.

Fig. 17 is a scanning electron microscope image of the Ti ₃ C ₂ Br ₂ Mxene material in Step 4. It can be seen that it exhibits an obvious "accordion" morphology structure unique to MXene material, because it is located between Ti ₃ C ₂ layers. The Al atoms are pulled away, and the newly embedded Br atoms cause the bonding between the Ti ₃ C ₂ Br ₂ layers to weaken and the interlayer distance to increase, thereby exhibiting a multilayer structure.

Example 10

In this example, the MXene material with I as the surface group is Ti ₃ C ₂ I ₂ , the precursor MAX phase is Ti ₃ AlC ₂ , and the transition metal chloride is CuI _2. These raw materials can be obtained through commercially available methods. . The preparation method of the Ti ₃ C ₂ I ₂ is as follows:

(1) Weigh 0.3 mol of CuI _{2 and} 0.05 mol of Ti ₃ AlC ₂ powder with a particle size of 10 μm, and grind and mix the above materials to obtain a mixed product.

(2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. The reaction conditions are: 700°C, 12 hours, protected by argon. After the tube furnace temperature was lowered to room temperature, the reaction product in the crucible was taken out.

FIG. 18 is a comparison of the XRD pattern of the precursor obtained by the Ti phase AlC ₂ with the MAX phase being Ti ₃ AlC ₂ . It can be seen from the comparison: after the reaction in step 3, the diffraction peaks (002), (004), (006) and so on are obviously shifted to a low angle, and the corresponding cell parameter c value increases to 24.99 nm, which is higher than Ti ₃ The c value of AlC ₂ is 18.48 nm. The changes in the XRD pattern above are consistent with the changes in the preparation of Ti ₃ C ₂ MXene using HF etching of Ti ₃ AlC ₂ , indicating that the Al atoms located between the Ti ₃ AlC ₂ layers are extracted and new atoms are embedded. In addition, distinct Cu and CuI diffraction peaks were detected in the product. This is because excessive CuI chemically reacted with Al atoms in Ti ₃ AlC ₂ , and the resulting MXene was Ti ₃ C ₂ I ₂ .

Figure 19a is a scanning electron microscope image of the product Ti ₃ C ₂ I ₂ MXene in Step 3, it can be seen that it exhibits an obvious "accordion" morphology structure unique to MXene material, because of the Al located between Ti ₃ C ₂ layers The atoms are pulled away, and the newly embedded I atoms cause the bonding between the Ti ₃ C ₂ I ₂ layers to weaken and the layer spacing to increase, thereby showing a multilayer structure. Figure 19b is the energy spectrum analysis of Figure 19a. It can be seen that the main element composition is Ti:I=31.28:20.60, which is close to 3:2. In addition, there is a small amount of O element in the product, which is introduced during the product washing process. Yes, a small amount of Cu is produced by the reduction of Cu ²⁺ during the reaction.

Example 11

In this example, the MXene material with Br as the surface group is Ti ₃ C ₂ Br ₂ , the precursor MAX phase is Ti ₃ SiC ₂ , and the transition metal bromide is CuBr _2. These raw materials can be obtained through commercially available methods. . The preparation method of the Ti ₃ C ₂ Br ₂ is as follows:

(1) Weigh 0.15 mol of CuBr _{2 and} 0.05 mol of Ti ₃ SiC ₂ powder with a particle size of 10 μm, and grind and mix the above materials to obtain a mixed product.

(2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. The reaction conditions were: 700°C, 10 hours, protected by argon. After the tube furnace temperature was lowered to room temperature, the reaction product in the crucible was taken out.

Example 12

In this embodiment, the MXene material with Br as the surface group is Ti ₃ C ₂ Br ₂ , the precursor MAX phase is Ti ₃ AlCN, and the transition metal bromide is CuBr _2. These raw materials can be obtained through commercial sales. The preparation method of the Ti ₃ C ₂ Br ₂ is as follows:

(1) Weigh 0.15 mol of CuBr _{2 and} 0.05 mol of Ti ₃ AlCN powder with a particle size of 10 μm, and grind and mix the above materials to obtain a mixed product.

Example 13

In this example, the MXene material with Br as the surface group is Sc ₃ C ₂ Br ₂ , the precursor MAX phase is Sc ₃ AlC ₂ , and the transition metal bromide is CuBr _2. These raw materials can be obtained through commercial sales and other methods. . The preparation method of the Ti ₃ C ₂ Br ₂ is as follows:

(1) Weigh 0.15 mol of CuBr _{2 and} 0.05 mol of Sc ₃ AlC ₂ powder with a particle size of 10 μm, and grind and mix the above materials to obtain a mixed product.

(4) Place the above solid product in 20 mL of APS solution with a molar fraction of 1 mol/L prepared in advance, and soak for 2 hours to remove the Cu element in it to obtain Sc ₃ C ₂ Br ₂ .

Example 14

In this example, the MXene material with I as the surface group is Ta ₃ C ₂ I ₂ , the precursor MAX phase is Ta ₃ AlC ₂ , and the transition metal iodide is CuI _2. These raw materials can be obtained through commercially available methods. . The preparation method of the Ta ₃ C ₂ I ₂ is as follows:

(1) Weigh 0.33 mol of CuI _{2 and} 0.03 mol of Ta ₃ AlC ₂ powder with a particle size of 10 μm, and grind and mix the above materials to obtain a mixed product.

(4) Place the above solid product in 20 mL of APS solution with a molar fraction of 1 mol/L prepared in advance, and soak for 2 h to remove the Cu element in it to obtain Ta ₃ C ₂ I ₂ .

Example 15

In this example, the MXene material with I as the surface group is Ti ₃ C ₂ I ₂ , the precursor MAX phase is Ti ₃ AlC ₂ , and the transition metal iodide is NiI _2. These raw materials can be obtained through commercial and other means. . The preparation method of the Ti ₃ C ₂ I ₂ is as follows:

(1) Weigh 0.15 mol of NiI _{2 and} 0.05 mol of Ti ₃ AlC ₂ powder with a particle size of 10 μm, and grind and mix the above materials to obtain a mixed product.

(4) Place the above solid product in 20 mL of a pre-formulated HCl solution with a mass fraction of 10% and soak for 2 hours to remove the Ni element in it to obtain Ti ₃ C ₂ I ₂ .

Example 16

In this embodiment, the MXene material with Br as the surface group is Ti ₂ CBr ₂ , the precursor MAX phase is Ti ₂ AlC, and the transition metal bromide is CuBr _2. These raw materials can all be obtained through commercially available methods. The preparation method of the Ti ₃ C ₂ Br ₂ is as follows:

(1) Weigh 0.15 mol of CuBr _{2 and} 0.05 mol of Ti ₂ AlC powder with a particle size of 10 μm, and grind and mix the above materials to obtain a mixed product.

(2) Place the mixture in a corundum crucible and place it in a high-temperature tube furnace for reaction. The reaction conditions were: 700°C, 24 hours, argon protection. After the tube furnace temperature was lowered to room temperature, the reaction product in the crucible was taken out.

Fig. 20 is a scanning electron micrograph of the product Ti ₃ C ₂ Br ₂ MXene material obtained in this example. It can be seen that it exhibits a distinct "accordion" morphology structure unique to MXene material, because it is located in the Ti ₂ C layer The Al atoms in between are extracted, and the newly embedded Br atoms cause the bonding between the Ti ₂ CBr ₂ layers to weaken and the interlayer distance to increase, thus showing a multilayer structure.

In addition, the inventors of this case also carried out related experiments by replacing the corresponding raw materials and process conditions in the foregoing Examples 8-16 with other raw materials and process conditions mentioned in this specification. The results all show that it is possible to obtain Br or I as the surface group MXene material.

In summary, compared to existing materials, the chemical stability and thermal stability of the MXene material with Br or I as the surface group provided by the foregoing examples of the present application is superior to that of the traditional MXene with surface group F, and its electrical properties, Dielectric properties, etc. have more adjustable space, the preparation method provided in this application is simple and easy to operate, environmentally friendly, avoiding many defects of the traditional preparation of MXene material by hydrofluoric acid etching method, the obtained Br or I is the surface The group MXene material has good applications in electrode materials for electrochemical energy storage, supercapacitor materials, electromagnetic absorption and shielding materials, catalysts and other fields.

Compared with the earlier reported MXene with -F, -O, etc. as the surface group, the -Br and -I surface groups obtained in this application can undergo a reversible redox reaction between the MXene layers. During the redox reaction process It can stably exist in the liquid or solid form between the MXene layers and provide stable reaction raw materials for battery charge and discharge reactions. This feature is not available for gas element groups such as -F and -O, so the -Br obtained in this application The MXene material with -I as the surface group can be independently used as a large-capacity, high-stability halogen battery electrode material in the field of lithium, sodium, zinc and other ion batteries.

The various aspects, embodiments, features, and examples of this application should be considered illustrative in all aspects and are not intended to limit this application, the scope of this application is only defined by the claims. Those skilled in the art will understand other embodiments, modifications, and uses without departing from the spirit and scope of the claimed application.

The use of titles and chapters in this application is not meant to limit this application; each chapter can be applied to any aspect, embodiment, or feature of this application.

Throughout this application, where the composition is described as having, containing, or including specific components, or where the process is described as having, containing, or including specific process steps, it is expected that the composition taught by this application is also substantially The above consists of the stated components or consists of the stated components, and the process taught in this application also basically consists of the stated process steps or consists of the stated process step groups.

Unless specifically stated otherwise, the use of the terms "include, includes, including" and "have, has, or having" should generally be understood as open-ended and not limiting.

It should be understood that the order of each step or the order of performing specific actions is not very important, as long as the teaching of this application remains operable. In addition, two or more steps or actions can be performed simultaneously.

In addition, the inventor of the present case also conducted experiments with other raw materials, process operations, and process conditions described in this specification with reference to the foregoing embodiments, and all obtained relatively satisfactory results.

Although the present application has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions and/or additions can be made and substance can be used without departing from the spirit and scope of the present application The effect replaces the elements of the described embodiments. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the application without departing from the scope of the application. Therefore, this document does not intend to limit the application to the disclosed specific embodiments for carrying out the application, but intends that the application will include all embodiments falling within the scope of the appended claims. In addition, unless specifically stated, any use of the terms first, second, etc. does not indicate any order or importance, but the terms first, second, etc. are used to distinguish one element from another.

Claims

An MXene material, characterized in that the molecular formula of the MXene material is expressed as M n+1 X n Y 2 , where M is any of the elements of Sc, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta One or a combination of two or more, X is any one or a combination of two elements of C and N, Y is any one or a combination of two or more elements of Cl, Br and I, n is 1, 2, 3 or 4.
The MXene material according to claim 1, wherein said X is C x N y , where x+y=1.
The MXene material according to claim 1, wherein the crystal structure of the MXene material is composed of M n+1 X n units and Y atoms located on the surface of the M n+1 X n units, wherein the Y atoms are M atoms are bonded together.
The MXene material according to claim 1, characterized in that: the form of the MXene material is a powder having a lamellar structure, and the lamellar structure is composed of a single layer or multiple layers M n+1 X n Y 2 ; Preferably, the lateral dimension of the sheet structure is 5 nm to 50 μm, and the thickness of the single sheet is 0.5 to 20 nm.
The preparation method of MXene material according to any one of claims 1 to 4, characterized in that it includes:

Mix the precursor MAX phase material with any one or a combination of two or more of transition metal chloride, transition metal bromide and transition metal iodide in a molar ratio of 1:3 to 1:10, and mix the obtained mixture Performing a high-temperature reaction at 400°C to 800°C for 1 to 48 hours in an inert atmosphere, and then performing post-treatment to obtain the MXene material;

The molecular formula of the precursor MAX phase material is expressed as M n+1 AX n , where M is any one or a combination of two or more elements of Sc, Ti, V, Cr, Zr, Nb, Mo, Hf, and Ta , A is selected from Group IIIA or IVA elements, X is any one or a combination of two elements of C and N, and n is 1, 2, 3 or 4.
The preparation method according to claim 5, wherein the precursor MAX phase material includes Ti 3 AlC 2 , Ti 3 SiC 2 , Ti 2 AlC, Ti 2 AlN, Ti 4 AlN 3 , Ti 2 GaC, V 2 AlC, V 2 GaC, Cr 2 GaN, Cr 2 AlC, Sc 2 AlC, Zr 2 AlC, Zr 2 SnC, Nb 2 AlC, Nb 4 AlC 3 , Mo 2 AlC, Mo 2 GaN, Hf 2 AlC, Hf 2 Any one or a combination of two or more of AlN, Ta 3 AlC 2 , and Ta 4 AlC 3 .
The preparation method according to claim 5, wherein the transition metal chloride includes any one or a combination of two or more of ZnCl 2 , CuCl 2 , CoCl 2 , FeCl 2 , and NiCl 2 ; and/or , The transition metal bromide includes any one or a combination of two or more of CuBr 2 , NiBr 2 , FeBr 2, and ZnBr 2 ; and/or, the transition metal iodide includes CuI 2 , NiI 2 , FeI 2 And any one or a combination of two or more of ZnI 2 .
The preparation method according to claim 5, characterized in that the precursor MAX phase material is any one or a combination of two or more of powder, bulk, and film; and/or, the transition metal chloride The compound, the transition metal bromide or the transition metal iodide is a powder, and the particle size is 500 nm to 1 μm.
The preparation method according to claim 5, wherein the post-treatment includes: after the high-temperature reaction is completed, removing the transition metal element generated by the reaction with an acid solution, and using deionized water to obtain the The reaction product is washed and then dried at 40 to 60°C to obtain the MXene material.
Use of the MXene material according to any one of claims 1 to 4 in the field of preparing electrode materials for electrochemical energy storage, supercapacitor materials, electromagnetic absorption and shielding materials, or catalysts.