MXene material with terminal group rich in target atoms and preparation method of MXene material

Abstract

The invention discloses an MXene material with a terminal group rich in target atoms and a preparation method of the MXene material. The preparation method comprises the following steps: 1) obtaining a multi-layer uniform halogen terminal group MXene material; (2) uniformly mixing and grinding the multi-layer uniform halogen-terminated MXene material, a metal lithium compound, potassium chloride and lithium chloride; and 3) placing the product obtained by grinding in a mixed atmosphere of hydrogen and inert gas, and carrying out an ion exchange reaction to obtain the MXene material of which the end group is rich in target atoms.

Description

Technical Field

[0001] The present invention belongs to the field of functional materials and relates to an MXene material with target atoms rich at the end groups and a preparation method thereof. Background Art

[0002] Two-dimensional transition metal carbides / nitrides (MXene) have characteristics such as high conductivity, high capacity, tunable surface chemistry, and easy dispersion in water, and are regarded as a new generation of promising functional nanomaterials; for example, as a supercapacitor electrode material, charge storage can be achieved through rapid surface redox reactions. Theoretical calculations and experimental verifications have found that surface functional groups are the key factors affecting the electronic properties and electrochemical energy storage performance of MXene materials. Yohan Dall'Agnese et al. treated Ti3C2T x in an alkaline electrolyte, causing partial substitution of the end group -F with the end group -O, and the capacitance increased by 4 times in a sulfuric acid electrolyte (Electrochem. Commun. 2014, 48, 118 - 122). The team of Fan Xiaobin from Tianjin University reacted Ti3C2T x with metallic sodium to remove the end group -F group, and the capacitance increased by 1.9 times in a sulfuric acid electrolyte (Energy Storage Materials, 2022, 50, 802 - 809). Therefore, optimizing the end group chemical structure of Ti3C2T x is crucial for improving electrochemical energy storage performance.

[0003] The team of Huang Qing from Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, first proposed a strategy to prepare MXene materials by etching Si atoms in the Ti3SiC2 phase with a Lewis acid molten salt CuCl2 as an etchant at 750 °C (in an inert gas atmosphere), and then treating with an ammonium persulfate solution (APS) to remove metallic Cu impurities. Due to the oxidizing property of the ammonium persulfate solution, more end group -O was inevitably introduced at the end groups, and the resulting multi-layer MXene with surface functional groups mainly composed of chlorine and oxygen atoms (Ti3C 1.94 Cl 0.77 O 1.71 , Nat. Mater. 2020, 19, 894). In 2023, the team of Patrice Simon, an academician of the French Academy of Sciences, used FeCl2 as an etchant and replaced the cleaning step using APS with a method of strongly adsorbing metallic impurity iron with a strong magnet to synthesize Ti3C2Cl x MXene with low oxygen content and chlorine end groups. Further, Ti3C2Cl x , Li3N, LiCl, and KCl were mixed evenly and calcined in an argon environment to prepare multi-layer MXene with surface functional groups mainly composed of nitrogen and oxygen atoms (Ti3C 1.95 N 0.80 O1.11 H 0.46 , Adv. Energy, Mater. 2023, 13, 2202709). However, the content of the target atom N at the end group is still low and lower than the content of the end group O. Therefore, it is of great scientific significance and research value to develop a preparation strategy for MXene with end groups rich in target atoms (such as N, S, Se, etc.) and reduce the content of end group -O. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned disadvantages of the prior art and provide an MXene material with end groups rich in target atoms and a preparation method thereof. The content of end group -O in the MXene material prepared by this method is significantly lower than that of the target atom.

[0005] To achieve the above object, the present invention discloses a preparation method for an MXene material with end groups rich in target atoms, including:

[0006] 1) Obtain a multi-layer homogeneous halogen-terminated MXene material;

[0007] 2) Mix and grind evenly the multi-layer homogeneous halogen-terminated MXene material, metal lithium compound, potassium chloride, and lithium chloride;

[0008] 3) Place the ground product in a mixed atmosphere of hydrogen and inert gas for an ion exchange reaction, and then obtain the MXene material with end groups rich in target atoms through washing, centrifugation, and drying.

[0009] A further improvement of the preparation method for the MXene material with end groups rich in target atoms according to the present invention is as follows:

[0010] Further, the process of step 1) is as follows:

[0011] 11) Grind evenly the MAX phase and the chloride ion Lewis acid or bromide ion Lewis acid in a molar ratio of 1:2 - 10 to obtain a mixed raw material;

[0012] 12) Place the mixed raw material obtained in step 11) in an inert atmosphere for an etching reaction to obtain a reaction product;

[0013] 13) Grind the reaction product obtained in step 12), and then obtain the multi-layer homogeneous halogen-terminated MXene material through washing, centrifugation, and drying.

[0014] Further, the MAX phase in step 11) is one or a mixture of more than one of Ti3AlC2, Ti2AlC, Ti3AlCN, Nb2AlC, and Ta2AlC; the chloride ion Lewis acid is one or a mixture of several of CdCl2, ZnCl2, and FeCl2; the bromide ion Lewis acid is one or a mixture of several of CdBr2, ZnBr2, and FeBr2.

[0015] Further, the specific process of step 12) is as follows:

[0016] Under an inert atmosphere, the mixed raw materials are heated to 500 - 800 °C at a heating rate of 3 - 10 °C / min and held for 5 - 24 h.

[0017] Further, the acidic solution in step 13) is 1 - 12 M hydrochloric acid or hydrobromic acid.

[0018] Further, the metal lithium compound in step 2) is Li3N, Li2S, Li2Se, Li2O, or Li2Te.

[0019] Further, the molar ratio of the multi-layer halogen-terminated MXene material, metal lithium compound, potassium chloride, and lithium chloride in step 2) is 1:1 - 5:50:35.

[0020] Further, the process of the temperature-rising reaction in step 3) is: heating to 500 - 800 °C and holding for 5 - 24 h; the mixed atmosphere of hydrogen / inert gas is a mixed atmosphere formed by 5 - 50 vol% hydrogen mixed with argon or nitrogen.

[0021] Compared with the existing synthesis technology, the present invention has the following advantages and technical effects:

[0022] When the MXene material with target atoms-rich end groups and its preparation method of the present invention are specifically operated, without increasing the reaction cycle and post-treatment process, the content of -O in the MXene end groups is significantly reduced, realizing end groups rich in target atoms. This is because hydrogen provides a reducing environment, preferentially reducing oxygen atoms or oxygen-containing functional groups in the molten salt reaction system, inhibiting the formation of -O in the MXene end groups, and promoting the stable adsorption of target atom end groups. Description of the Drawings

[0023] The attached drawings / table forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0024] Figure 1 For the SEM and elemental distribution diagrams of Ti3C2Cl x and Ti3C2N x ;

[0025] Figure 2 It is Ti3C2Cl x and Ti3C2N x TEM images. Specific implementation manners

[0026] The following combines examples to further describe the present invention in detail, making the purpose, technical solution and advantages of the present invention clearer, but the implementation manners of the present invention are not limited thereto.

[0027] Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0028] Example 1

[0029] The preparation method of the MXene material with target atoms rich in end groups according to the present invention includes the following steps:

[0030] Grind 0.5 g of Ti3AlC2 (400 mesh) and 2 g of CdCl2 in a mortar for 10 - 20 min, then place it in an alumina crucible, and heat it to 610 °C at a heating rate of 5 °C / min under an argon atmosphere, keep it for 6 h and then cool it to room temperature; grind the reaction product into powder, and then react it fully in 12 M hydrochloric acid solution for 4 h, then wash it repeatedly with deionized water and ethanol, centrifuge, and finally vacuum dry the precipitate at 80 °C for 12 h to obtain Ti3C2Cl x Take Ti3C2Cl x Mix it with Li3N, LiCl and KCl in a molar ratio of 1:2:50:35 and grind it in a mortar for 10 - 20 min, then transfer the mixture to an alumina crucible, heat it to 550 °C at a heating rate of 5 °C / min under a hydrogen - argon atmosphere, keep it for 12 h and then cool it to room temperature, then wash it repeatedly with deionized water and ethanol, centrifuge, and finally vacuum dry the precipitate at 80 °C for 12 h to obtain Ti3C2N x MXene material (Ti3C 1.91 N 1.52 O 0.31 H 0.60 ), and the element content is shown in Table 1.

[0031] Table 1

[0032] <![CDATA[Ti3C2N x > Ti C N O H Al Cd wt. % 68.22 10.88 10.14 2.34 0.29 2.64 0.87 mol. % 3 1.91 1.52 0.31 0.60 0.21 0.02

[0033] Comparative Example 1

[0034] 0.5 g of Ti3AlC2 (400 mesh) and 2 g of CdCl2 were ground in a mortar for 10 - 20 min. Subsequently, they were placed in an alumina crucible and heated to 610 °C at a heating rate of 5 °C / min under an argon atmosphere. After holding for 6 h, it was then cooled to room temperature. The reaction product was ground into powder, fully reacted in 12 M hydrochloric acid solution for 4 h, and then repeatedly washed with deionized water and ethanol, centrifuged. Finally, the precipitate was vacuum dried at 80 °C for 12 h to obtain Ti3C2Cl x . Further, Ti3C2Cl x was put into a mortar and ground with Li3N, LiCl and KCl in a molar ratio of 1:2:50:35 for 10 - 20 min; then the mixture was transferred to an alumina crucible and heated to 550 °C at a heating rate of 5 °C / min under an argon atmosphere. After holding for 12 h, it was cooled to room temperature, and then repeatedly washed with deionized water and ethanol, centrifuged. Finally, the precipitate was vacuum dried at 80 °C for 12 h to obtain Ti3C2N x MXene material.

[0035] Comparative Example 2

[0036] 0.5 g of Ti3AlC2 (400 mesh) and 2 g of CdCl2 were ground in a mortar for 10 - 20 min. Subsequently, they were placed in an alumina crucible and heated to 610 °C at a heating rate of 5 °C / min under a hydrogen - argon atmosphere. After holding for 6 h, it was then cooled to room temperature. The reaction product was ground into powder, fully reacted in 12 M hydrochloric acid solution for 4 h, and then repeatedly washed with deionized water and ethanol, centrifuged. Finally, the precipitate was vacuum dried at 80 °C for 12 h to obtain Ti3C2Cl x , Ti3C2Cl x was put into a mortar and ground with Li3N, LiCl and KCl in a molar ratio of 1:2:50:35 for 10 - 20 min. Then the mixture was transferred to an alumina crucible and heated to 550 °C at a heating rate of 5 °C / min under a hydrogen - argon atmosphere. After holding for 12 h, it was cooled to room temperature, and then repeatedly washed with deionized water and ethanol, centrifuged. Finally, the precipitate was vacuum dried at 80 °C for 12 h to obtain Ti3C2N x MXene material.

[0037] The atomic content of surface - terminal N in the Ti3C2N prepared according to Example 1 x is significantly higher than that in Comparative Example 1 and Comparative Example 2.

[0038] Example 2

[0039] The preparation method of the MXene material with terminal groups rich in target atoms according to the present invention includes the following steps:

[0040] 1) Grind MAX phase and chloride ion Lewis acid or bromide ion Lewis acid evenly in a mortar at a molar ratio of 1:8 to obtain a mixed raw material;

[0041] 2) Put the mixed raw material obtained in step 1) into a high-temperature resistant crucible, and carry out an etching reaction under an inert atmosphere to obtain a reaction product;

[0042] 3) Grind and crush the reaction product obtained in step 2), then place it in a non-oxidizing acidic solution and stir to react to remove the metal impurities displaced by the etching reaction. Subsequently, wash it repeatedly with deionized water and ethanol, centrifuge, and finally vacuum-dry the precipitate at 80 °C for 12 h to obtain a multi-layer halogen-terminated MXene material;

[0043] 4) Grind the multi-layer halogen-terminated MXene material, metal lithium compound, potassium chloride, and lithium chloride evenly in an argon glove box. Among them, the molar ratio of the multi-layer halogen-terminated MXene material to the metal lithium compound, potassium chloride, and lithium chloride is 1:4:50:35;

[0044] 5) Put the product ground in step 4) into a high-temperature resistant crucible, and react under a hydrogen-inert gas mixed atmosphere to replace the MXene terminal atoms and reduce the content of terminal O at the same time, to obtain a MXene material rich in target atoms at the terminal.

[0045] In this embodiment, the MAX phase in step 1) is Ti3AlC2; the chloride ion Lewis acid is CdCl2, and the bromide ion Lewis acid is CdBr2.

[0046] The process of carrying out the etching reaction under an inert atmosphere in step 2) to obtain a reaction product is as follows: Under an argon atmosphere, heat the mixed raw material at a heating rate of 10 °C / min to 700 °C and keep it warm for 5 h.

[0047] The acidic solution in step 3) is 10 M hydrochloric acid or hydrobromic acid, and the reaction time of the stirring reaction in step 3) is 4 h.

[0048] The metal lithium compound in step 4) is Li3N.

[0049] The specific process of step 5) is:

[0050] Put the product ground in step 4) into a high-temperature resistant crucible, and under a hydrogen-inert gas mixed atmosphere, heat it to 600 °C and keep it warm for 10 h.

[0051] The hydrogen-inert gas mixed atmosphere in step 5) is a mixed gas formed by mixing 45 vol% of hydrogen with argon or nitrogen.

[0052] Example Three

[0053] The preparation method of the MXene material with end groups rich in target atoms according to the present invention includes the following steps:

[0054] 1) Grind the MAX phase and a chloride ion Lewis acid or a bromide ion Lewis acid evenly in a mortar according to a molar ratio of 1:4 to obtain a mixed raw material;

[0055] 2) Put the mixed raw material obtained in step 1) into a high-temperature resistant crucible and carry out an etching reaction under an inert atmosphere to obtain a reaction product;

[0056] 3) Grind and crush the reaction product obtained in step 2), then place it in a non-oxidizing acidic solution and stir to react to remove the metal impurities displaced by the etching reaction. Wash and centrifuge with deionized water and ethanol, and dry the precipitate in a vacuum drying oven to obtain a multi-layer homogeneous halogen-terminated MXene material;

[0057] 4) Grind the multi-layer homogeneous halogen-terminated MXene material, lithium metal compound, potassium chloride and lithium chloride evenly in an argon glove box. Among them, the molar ratio of the multi-layer halogen-terminated MXene material to the lithium metal compound, potassium chloride and lithium chloride is 1:1:50:35;

[0058] 5) Put the product ground in step 4) into a high-temperature resistant crucible and react under a hydrogen-inert gas mixed atmosphere to achieve the substitution of MXene end group atoms while reducing the content of end group O to obtain a Ti3CNS x MXene material.

[0059] In this embodiment, the MAX phase in step 1) is Ti3AlCN; the chloride ion Lewis acid is a mixture of CdCl2 and ZnCl2, and the bromide ion Lewis acid is a mixture of CdBr2 and ZnBr2.

[0060] In step 2), the process of carrying out the etching reaction under an inert atmosphere to obtain a reaction product is as follows: Under a nitrogen atmosphere, heat the mixed raw material to 700 °C at a heating rate of 5 °C / min and keep it warm for 20 h.

[0061] The acidic solution in step 3) is 5M hydrochloric acid or hydrobromic acid, and the reaction time of the stirring reaction in step 3) is 5 h.

[0062] The lithium metal compound in step 4) is Li2S.

[0063] The specific process of step 5) is as follows:

[0064] Put the product ground in step 4) into a high-temperature resistant crucible, and then under a hydrogen-inert gas mixed atmosphere, heat it to 550 °C and keep it warm for reaction for 12 h.

[0065] In step 5), the hydrogen-inert gas mixed atmosphere is a mixed gas formed by mixing 10 vol% of hydrogen with argon or nitrogen.

[0066] Example 4

[0067] The preparation method of the MXene material with terminal groups rich in target atoms according to the present invention includes the following steps:

[0068] 1) Grind the MAX phase and a chloride ion Lewis acid or a bromide ion Lewis acid evenly in a mortar according to a molar ratio of 1:2 to 10 to obtain a mixed raw material;

[0069] 2) Put the mixed raw material obtained in step 1) into a high-temperature resistant crucible, and carry out an etching reaction in an inert atmosphere to obtain a reaction product;

[0070] 3) Grind and crush the reaction product obtained in step 2), then place it in a non-oxidizing acidic solution and stir to react to remove the metal impurities displaced by the etching reaction. Subsequently, wash it repeatedly with deionized water and ethanol, centrifuge it, and finally vacuum dry the precipitate at 80 °C for 12 h to obtain a multi-layer homogeneous halogen-terminated MXene material;

[0071] 4) Grind the multi-layer halogen-terminated MXene material, lithium metal compound, potassium chloride and lithium chloride evenly in an argon glove box. Among them, the molar ratio of the multi-layer halogen-terminated MXene material to the lithium metal compound, potassium chloride and lithium chloride is 1:3:50:35;

[0072] 5) Put the product ground in step 4) into a high-temperature resistant crucible, and then react in a hydrogen-inert gas mixed atmosphere to achieve the substitution of MXene terminal atoms while reducing the content of terminal O, so as to obtain a MXene material with terminal groups rich in target atoms.

[0073] In this example, the MAX phase in step 1) is Ti2AlC; the chloride ion Lewis acid is a mixture of CdCl2 and ZnCl2, and the bromide ion Lewis acid is a mixture of CdBr2 and ZnBr2.

[0074] The process of carrying out the etching reaction in an inert atmosphere in step 2) to obtain a reaction product is as follows: in an inert atmosphere, the mixed raw material is heated to 600 °C at a heating rate of 10 °C / min and kept warm for 10 h.

[0075] The acidic solution in step 3) is 6M hydrochloric acid or hydrobromic acid, and the reaction time of the stirring reaction in step 3) is 5 h.

[0076] The lithium metal compound in step 4) is Li2Se.

[0077] The specific process of step 5) is as follows:

[0078] Put the product obtained by grinding in step 4) into a high-temperature resistant crucible, and then heat it to 600 °C under a hydrogen-inert gas mixed atmosphere and hold the reaction for 10 h.

[0079] In step 5), the hydrogen-inert gas mixed atmosphere is a mixed gas formed by mixing 30 vol% of hydrogen with argon or nitrogen.

[0080] After considering the specification and the disclosure of the invention, those skilled in the art will readily conceive of other embodiments of the present invention. This application is intended to cover any variations, uses, or adaptations of the present invention, which follow the general principles of the present invention and include known common knowledge or conventional technical means in the technical field not disclosed by the present invention. The specification and examples are only regarded as exemplary, and the true scope and spirit of the present invention are pointed out by the following claims.

[0081] It should be understood that the present invention is not limited to the microstructures already described and shown in the drawings. The scope of the present invention is only limited by the appended claims.

[0082] The above are only the preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modifications or changes made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A preparation method of an MXene material with end groups rich in target atoms, characterized in that, Including: 1) Obtaining a multi-layer homogeneous halogen-terminated MXene material; 2) Mixing and grinding evenly the multi-layer homogeneous halogen-terminated MXene material, metal lithium compound, potassium chloride and lithium chloride; 3) Placing the ground product under a mixed atmosphere of hydrogen and inert gas for an ion exchange reaction, and then washing, centrifuging and drying to obtain a MXene material with end groups rich in target atoms.

2. The preparation method of the MXene material with a target atom-rich end group according to claim 1, characterized in that, The process of step 1) is as follows: 11) Grinding evenly the MAX phase and a chloride ion Lewis acid or a bromide ion Lewis acid in a molar ratio of 1:2 to 10 to obtain a mixed raw material; 12) Placing the mixed raw material obtained in step 11) under an inert atmosphere for an etching reaction to obtain a reaction product; 13) Grinding the reaction product obtained in step 12), then stirring and reacting in a non-oxidizing acid solution, and then washing, centrifuging and drying to obtain a multi-layer homogeneous halogen-terminated MXene material.

3. The preparation method of the MXene material with end groups rich in target atoms according to claim 2, characterized in that, The MAX phase in step 11) is one or a mixture of more than one of Ti3AlC2, Ti2AlC, Ti3AlCN, Nb2AlC and Ta2AlC.

4. The preparation method of the MXene material with end groups rich in target atoms according to claim 2, wherein, The chloride ion Lewis acid in step 11) is one or a mixture of several of CdCl2, ZnCl2 and FeCl2; the bromide ion Lewis acid is one or a mixture of several of CdBr2, ZnBr2 and FeBr2.

5. The method for preparing an MXene material rich in target atoms at the end groups according to claim 2, characterized in that, The specific process of step 12) is as follows: Under an inert atmosphere, heating the mixed raw material at a heating rate of 3 to 10 °C / min to 500 to 800 °C and holding for 5 - 24 h.

6. The preparation method of the MXene material with end groups rich in target atoms according to claim 2, wherein, The acid solution in step 13) is 1 - 12 M hydrochloric acid or hydrobromic acid.

7. The method for preparing an MXene material with a target atom-rich end group according to claim 1, wherein, The metal lithium compound in step 2) is Li3N, Li2S, Li2Se, Li2O or Li2Te.

8. The preparation method of the MXene material with end groups rich in target atoms according to claim 1, characterized in that, The molar ratio of the multi-layer halogen-terminated MXene material, metal lithium compound, potassium chloride and lithium chloride in step 2) is 1:1 - 5:50:

35.

9. The preparation method of the MXene material with end groups rich in target atoms according to claim 1, characterized in that, The process of the temperature-rising reaction in step 3) is as follows: heating to 500 - 800 °C and holding for 5 - 24 h; the mixed atmosphere of hydrogen / inert gas is a mixed atmosphere formed by 5 - 50 vol% hydrogen mixed with argon or nitrogen.

10. An MXene material with a target atom-rich end group, characterized in that, Prepared by the preparation method of the MXene material with end groups rich in target atoms according to any one of claims 1 - 9.

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