A method for preparing layered MXenes material by chlorine-containing acid etching

Abstract

The application belongs to the technical field of nanometer layered materials, and particularly relates to a method for preparing layered MXenes materials by using chloric acid etching, wherein the MAX phase material is etched by using chloric acid, the chloric acid is an oxygen-containing acid and has strong acidity, the influence of a fluorine-containing etching agent on the performance of the material can be avoided, meanwhile, the application has low requirements on equipment, short time consumption, high preparation efficiency, simple process, and the obtained layered MXenes material is in the form of large flakes, and the average side length of the flakes is 1.5-2.0 mu m.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of nanolayer materials, in particular to a method for preparing a layered MXenes material through chloric acid etching. BACKGROUND

[0002] Since Geim et al. first prepared graphene by mechanical exfoliation in 2004, two-dimensional materials have been widely studied due to their unique structure and excellent physical and chemical properties. MXenes, a new two-dimensional material, were discovered at Drexel University in 2011. MXenes and graphene are both two-dimensional sheet structures, and not only have the characteristics of high specific surface area and high conductivity of graphene, but also have adjustable nanolayer thickness, and advantages of conductivity and hydrophilicity. The commonly used method is to form the layered structure of MXenes by etching the "A" element of the precursor MAX phase. The parameters of this top-down selective etching process will affect the structure of MXenes. The MAX precursor is a ceramic material with a layered hexagonal system composed of M, A and X elements, wherein M represents transition metal elements such as Ti, Mo, A represents ⅢA and ⅣA elements such as Al and Si, and X is mostly C and N. The composition of M, A and X is considered to be a key parameter affecting the ability and method of synthesizing MXenes. The chemical formula of MXenes is M n+1 X n T x (n = 1, 2 or 3), wherein M is a transition metal (such as Sc, V, Ti, Zr and Cr), X is carbon, nitrogen or carbon-nitrogen, and T is a surface group (such as O, OH or F). In recent years, MXenes materials have developed rapidly in various fields, and the preparation process has become more and more rich. From the HF solution used when it was first discovered to the current various methods and processes such as molten salt, in-situ etching, high-temperature alkali solution, Lewis acid etching, chemical vapor deposition (CVD) and electrochemical method to improve the application performance.

[0003] Different end groups or special morphologies are generated by using different synthesis routes, which have certain influence on subsequent applications, so the selection of preparation method is particularly important. The commonly used etching method consumes a long time, some equipment is difficult to operate, and the yield of the finished product is low, and the small size sample is not conducive to subsequent application (Nature Materials, 14(11), 1135-1141). Due to the problems of yield and efficiency, HF acid containing F ions or in-situ formed HF are mostly used to etch the precursor MAX phase (Energy Storage Materials 63(2023)102977). However, fluorine ions have a certain influence on the performance of the material itself, for example, the F group on the surface will reduce the conductivity, because the attached F on the surface hinders the migration of electrolyte ions, so that the electrochemical active site is reduced (J. Am. Chem. Soc. 2012, 134, 16909-16916). Therefore, how to improve the preparation method of layered MXenes material without F ions to achieve simple preparation process, non-complicated equipment requirements, high etching efficiency, time reduction and the like is still the research focus in the field at present. SUMMARY

[0004] In order to solve the problems existing in the prior art, the main purpose of the present application is to provide a method for etching and preparing layered MXenes material containing chloric acid.

[0005] In order to solve the above technical problems, according to one aspect of the present application, the present application provides the following technical scheme:

[0006] A method for etching and preparing layered MXenes material containing chloric acid, wherein MAX phase material powder and chloric acid etchant are added to a reaction kettle, the reaction kettle is heated, the heating temperature is 40-60℃, the reaction time is 1-6h, then centrifugal, freeze-drying treatment is carried out, and layered MXenes material is obtained.

[0007] As a preferred scheme of the method for etching and preparing layered MXenes material containing chloric acid, wherein: the chloric acid etchant is at least one of perchloric acid (HClO4), chloric acid (HClO3), chlorous acid (HClO2) and hypochlorous acid (HClO).

[0008] As a preferred scheme of the method for etching and preparing layered MXenes material containing chloric acid, wherein: the concentration of the chloric acid etchant is 10-30wt%.

[0009] As a preferred scheme of the method for preparing layered MXenes material by chlorine-containing acid etching, the MAX phase material is one of Ti3AlC2, Ti2AlC, Nb2AlC, V2AlC, Cr2AlC and Ta4AlC3.

[0010] As a preferred scheme of the method for preparing layered MXenes material by chlorine-containing acid etching, the mass ratio of the MAX phase powder to the chlorine-containing acid etchant is 1:(4-6).

[0011] As a preferred scheme of the method for preparing layered MXenes material by chlorine-containing acid etching, the centrifugal processing speed is 2500-3000 rpm, and the centrifugal processing time is 4-8 min.

[0012] As a preferred scheme of the method for preparing layered MXenes material by chlorine-containing acid etching, the freeze-drying is carried out in a vacuum environment, and the vacuum pressure is less than or equal to 10 Pa.

[0013] As a preferred scheme of the method for preparing layered MXenes material by chlorine-containing acid etching, the freeze-drying temperature is-90 to-100 DEG C, and the freeze-drying time is 24-48 h.

[0014] The beneficial effects of the present application are as follows:

[0015] The present application provides a method for preparing layered MXenes material by chlorine-containing acid etching. The MAX phase material is etched by using chlorine-containing acid. The chlorine-containing acid is an oxygen-containing acid with strong acidity, which can avoid the influence of fluorine-containing etchant on the performance of the material. Meanwhile, the present application has low equipment requirements, short time consumption, high preparation efficiency and simple process. The obtained layered MXenes material has a large flake, and the average side length of the flake is 1.5-2.0 microns. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained according to the structures shown in the drawings without creative labor.

[0017] Figure 1 The SEM image of the MAX phase Ta4AlC3.

[0018] Figure 2 The SEM image of the MXene material prepared in Example 1 of the present application.

[0019] Figure 3 TEM image of MXene material prepared for Example 1 of the present application.

[0020] Figure 4 SEM image of material prepared for Comparative Example 1 of the present application.

[0021] Figure 5 SEM image of material prepared for Comparative Example 2 of the present application.

[0022] Figure 6 SEM image of material prepared for Comparative Example 3 of the present application.

[0023] The objectives, features and advantages of the present application will be further illustrated in conjunction with the embodiments, with reference to the accompanying drawings. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0025] According to an aspect of the present application, the present application provides the following technical solutions:

[0026] A method for preparing layered MXenes material by chlorine-containing acid etching, wherein MAX phase powder and chlorine-containing acid etchant are added into a reaction kettle, mixed uniformly, and then the reaction kettle is air-exhausted using inert gas, sealed, heated, and heated at a temperature of 40-60℃ for 1-6h, followed by centrifugation and freeze-drying treatment to obtain layered MXenes material. Specifically, the heating temperature can be, for example, any one of 40℃, 45℃, 50℃, 55℃, 60℃, or a range between any two of them, and the reaction time can be, for example, any one of 1h, 2h, 3h, 4h, 5h, 6h, or a range between any two of them.

[0027] Preferably, the chlorine-containing acid etchant is at least one of perchloric acid (HClO4), chloric acid (HClO3), chlorous acid (HClO2), and hypochlorous acid (HClO).

[0028] Preferably, the concentration of the chlorine-containing acid etchant is 10-30wt%. Specifically, the concentration of the chlorine-containing acid etchant can be, for example, any one of 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, or a range between any two of them.

[0029] Preferably, the MAX phase material is one of Ti3AlC2, Ti2AlC, Nb2AlC, V2AlC, Cr2AlC, Ta4AlC3.

[0030] Preferably, the mass ratio of the MAX phase powder to the chlorine-containing acid etchant is 1:(4-6). Specifically, the mass ratio of the MAX phase powder to the chlorine-containing acid etchant can be, for example, any one of 1:4, 1:4.5, 1:5, 1:5.5, 1:6 or a range between any two of them.

[0031] Preferably, the centrifugal treatment can be performed multiple times as needed, and the speed of each centrifugal treatment is 2500-3000 rpm, and the time of each centrifugal treatment is 4-8 min. Specifically, the speed of the centrifugal treatment can be, for example, any one of 2500 rpm, 2600 rpm, 2700 rpm, 2800 rpm, 2900 rpm, 3000 rpm or a range between any two of them; the time of the centrifugal treatment can be, for example, any one of 4 min, 5 min, 6 min, 7 min, 8 min or a range between any two of them.

[0032] Preferably, in the step S2, quick freezing is performed using liquid nitrogen before freeze-drying.

[0033] Preferably, in the step S2, freeze-drying is performed in a vacuum environment, and the vacuum pressure is ≤10 Pa.

[0034] Preferably, in the step S2, the freeze-drying temperature is -90 to -100℃, and the freeze-drying time is 24-48 h. Specifically, the freeze-drying temperature can be, for example, any one of -90℃, -92℃, -95℃, -98℃, -100℃ or a range between any two of them, and the freeze-drying time can be, for example, any one of 24 h, 30 h, 36 h, 42 h, 48 h or a range between any two of them.

[0035] The technical solutions of the present application are further described below in combination with specific examples.

[0036] Example 1

[0037] A method for preparing layered MXenes material by chlorine-containing acid etching, MAX phase Ta4AlC3 powder with a mass ratio of 1:5 (the SEM image thereof is as shown in FIG. 1) is used as the raw material. Figure 1The reaction kettle was sealed and heated, the heating temperature was 50℃, the reaction time was 4h, and after the reaction was completed, it was cooled to room temperature. The solution after the reaction was poured out and washed to neutral, and then centrifuged, freeze-dried, and treated. Multiple centrifugal treatments were performed, the rotation speed of the centrifugal treatment was 3000rpm, and the total time of multiple centrifugal treatments was 18min. The supernatant after centrifugation was first rapidly frozen using liquid nitrogen, and then freeze-dried, freeze-dried at 1Pa pressure vacuum, -95℃ for 36h, to obtain layered Ta4C3T x MXenes material.

[0038] The layered Ta4C3T x MXenes material prepared in this example has a SEM image as shown in Figure 2 , and a TEM image as shown in Figure 3 . As can be seen from Figure 2 , the Ta4C3T x MXenes material after reaction with perchloric acid presents a layered structure; as can be seen from Figure 3 , the Ta4C3T x MXenes material has a thinner nanosheet and a larger lateral size.

[0039] Example 2

[0040] A method for preparing a layered MXenes material by chloric acid etching, MAX phase Ta4AlC3 powder with a mass ratio of 1:5 and chloric acid etchant with a concentration of 15wt% were added to the reaction kettle, mixed uniformly, and then the reaction kettle was air-exhausted using inert gas. The reaction kettle was sealed and heated, the heating temperature was 50℃, the reaction time was 3.5h, and after the reaction was completed, it was cooled to room temperature. The solution after the reaction was poured out and washed to neutral, and then centrifuged, freeze-dried, and treated. Multiple centrifugal treatments were performed, the rotation speed of the centrifugal treatment was 3000rpm, and the total time of multiple centrifugal treatments was 30min. The supernatant after centrifugation was first rapidly frozen using liquid nitrogen, and then freeze-dried, freeze-dried at 1Pa pressure vacuum, -96℃ for 42h, to obtain layered Ta4C3T x MXenes material.

[0041] Example 3

[0042] A method for preparing layered MXenes material by chlorine-containing acid etching, wherein MAX phase Ta4AlC3 powder with a mass ratio of 1:5 and chlorous acid etchant with a concentration of 20wt% are added into a reaction kettle, mixed uniformly, and then the reaction kettle is discharged of air using inert gas, sealed, heated, and cooled to room temperature after heating at a temperature of 55 DEG C for 5h; the solution after reaction is poured out, washed to neutral, and then centrifuged and freeze-dried, and multiple centrifugation treatments are performed at a speed of 3000rpm for a total time of 36min; the supernatant after centrifugation is first rapidly frozen using liquid nitrogen, and then freeze-dried at a pressure of 1Pa under vacuum at-90 DEG C for 48h to obtain layered Ta4C3T x MXenes material.

[0043] Example 4

[0044] A method for preparing layered MXenes material by chlorine-containing acid etching, wherein MAX phase Ta4AlC3 powder with a mass ratio of 1:5 and hypochlorous acid etchant with a concentration of 30wt% are added into a reaction kettle, mixed uniformly, and then the reaction kettle is discharged of air using inert gas, sealed, heated, and cooled to room temperature after heating at a temperature of 60 DEG C for 3h; the solution after reaction is poured out, washed to neutral, and then centrifuged and freeze-dried, and multiple centrifugation treatments are performed at a speed of 3000rpm for a total time of 48min; the supernatant after centrifugation is first rapidly frozen using liquid nitrogen, and then freeze-dried at a pressure of 1Pa under vacuum at-100 DEG C for 48h to obtain layered Ta4C3T x MXenes material.

[0045] Example 5

[0046] A method for preparing layered MXenes material by chlorine-containing acid etching, wherein MAX phase Ta4AlC3 powder with a mass ratio of 1:5 and chlorine-containing mixed acid (10wt% perchloric acid: 15wt% chloric acid: 20wt% chlorous acid: 30wt% hypochlorous acid = 1:1:1:1 (mass ratio)) etchant are added into a reaction kettle, mixed uniformly, and then the reaction kettle is discharged of air using inert gas, sealed, heated, and cooled to room temperature after heating at a temperature of 50 DEG C for 3h; the solution after reaction is poured out, washed to neutral, and then centrifuged and freeze-dried, and multiple centrifugation treatments are performed at a speed of 3000rpm for a total time of 20min; the supernatant after centrifugation is first rapidly frozen using liquid nitrogen, and then freeze-dried at a pressure of 1Pa under vacuum at-95 DEG C for 24h to obtain layered Ta4C3T x MXenes material.

[0047] Example 6

[0048] A method for preparing layered MXenes material by chlorine-containing acid etching, MAX phase Ti3AlC2 powder with a mass ratio of 1:5 and perchloric acid etchant with a concentration of 10wt% are added into a reaction kettle, after uniform mixing, inert gas is used to discharge the air in the reaction kettle, after sealing, the reaction kettle is heated, the heating temperature is 50℃, the reaction time is 1.5h, after the reaction is completed, it is cooled to room temperature, the solution after reaction is poured out and washed to neutral, then centrifugation and freeze-drying treatment are carried out, multiple centrifugation treatment is carried out, the rotation speed of centrifugation treatment is 2500rpm, the total time of multiple centrifugation treatment is 24min; the supernatant after centrifugation is first frozen using liquid nitrogen, then freeze-drying treatment is carried out, under the pressure vacuum of 1Pa, freeze-drying at-98℃ for 36h, layered Ti3C2T x MXenes material.

[0049] Example 7

[0050] A method for preparing layered MXenes material by chlorine-containing acid etching, MAX phase Ti2AlC powder with a mass ratio of 1:4 and perchloric acid etchant with a concentration of 10wt% are added into a reaction kettle, after uniform mixing, inert gas is used to discharge the air in the reaction kettle, after sealing, the reaction kettle is heated, the heating temperature is 50℃, the reaction time is 1h, after the reaction is completed, it is cooled to room temperature, the solution after reaction is poured out and washed to neutral, then centrifugation and freeze-drying treatment are carried out, multiple centrifugation treatment is carried out, the rotation speed of centrifugation treatment is 3500rpm, the total time of multiple centrifugation treatment is 28min; the supernatant after centrifugation is first frozen using liquid nitrogen, then freeze-drying treatment is carried out, under the pressure vacuum of 1Pa, freeze-drying at-95℃ for 48h, layered Ti2CT x MXenes material.

[0051] Example 8

[0052] A method for preparing layered MXenes material by chlorine-containing acid etching, MAX phase Nb2AlC powder with a mass ratio of 1:6 and perchloric acid etchant with a concentration of 10wt% are added into a reaction kettle, after uniform mixing, inert gas is used to discharge the air in the reaction kettle, after sealing, the reaction kettle is heated, the heating temperature is 50℃, the reaction time is 3h, after the reaction is completed, it is cooled to room temperature, the solution after reaction is poured out and washed to neutral, then centrifugation and freeze-drying treatment are carried out, multiple centrifugation treatment is carried out, the rotation speed of centrifugation treatment is 3500rpm, the total time of multiple centrifugation treatment is 20min; the supernatant after centrifugation is first frozen using liquid nitrogen, then freeze-drying treatment is carried out, under the pressure vacuum of 1Pa, freeze-drying at-95℃ for 48h, layered Nb2CT x MXenes material.

[0053] Example 9

[0054] A method for preparing a layered MXenes material by etching with a chloric acid, wherein a MAX phase V2AlC powder and a perchloric acid etchant with a concentration of 10wt% are mixed in a mass ratio of 1:5, the reaction kettle is then sealed after being mixed uniformly and air is discharged using an inert gas, and the reaction kettle is heated to a temperature of 50℃ for 4h, and then cooled to room temperature, the solution after the reaction is poured out and washed to neutral, and then centrifuged and freeze-dried, and the centrifugation is repeated for a total of 18min at a speed of 3500rpm; the supernatant after centrifugation is first rapidly frozen using liquid nitrogen, and then freeze-dried under a pressure of 1Pa vacuum at-97℃ for 42h, to obtain a layered V2CT x MXenes material.

[0055] Comparative Example 1

[0056] The difference from Example 1 is that the heating temperature is 30℃.

[0057] The SEM image of the material prepared in this comparative example is shown in Figure 4 From Figure 4 which it can be clearly observed that the material prepared in Comparative Example 1 and the MAX phase Ta4AlC3 powder that has not undergone etching reaction (as shown in Figure 1 ) are almost indistinguishable, both of which are tightly stacked in morphology, and do not belong to the layered Ta4C3T x MXenes material.

[0058] Comparative Example 2

[0059] The difference from Example 1 is that the heating time is 0.5h.

[0060] The SEM image of the material prepared in this comparative example is shown in Figure 5 From Figure 4 which it can be clearly observed that the material prepared in Comparative Example 2 and the MAX phase Ta4AlC3 powder that has not undergone etching reaction (as shown in Figure 1 ) are almost indistinguishable, both of which are tightly stacked in morphology, and do not belong to the layered Ta4C3T x MXenes material.

[0061] Comparative Example 3

[0062] The difference from Example 1 is that the mass ratio of the MAX phase powder to the chloric acid etchant is 1:3.

[0063] The SEM image of the material prepared in this comparative example is shown in Figure 6 From Figure 6It can be obviously observed that the material prepared by the comparative example 3 has a cracking morphology, but it is almost the same as the MAX phase Ta4AlC3 powder (as shown in Figure 1 FIG. 2) without etching reaction.

[0064] As can be seen from the above examples and comparative examples, the present application uses the chlorine-containing acid to realize the etching of the MAX phase material. The chlorine-containing acid is an oxygen-containing acid and has strong acidity, which can avoid the influence of the fluorine-containing etchant on the performance of the material itself. Meanwhile, the present application has low requirement for equipment, short time consumption, high preparation efficiency, simple process, and the obtained layered MXenes material has a large flake, and the average side length of the flake is 1.5-2.0 μm.

[0065] The above only describes the preferred embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation, direct / indirect application in other related technical fields, or the like made by using the content of the present application under the inventive concept of the present application is included in the patent protection scope of the present application.

Claims

1. A method of producing layered MXenes material by chlorine-containing acid etching, characterized in that, The MAX phase material powder and the chlorine-containing acid etchant are added into a reaction kettle, the reaction kettle is heated, the heating temperature is 40-60 DEG C, the reaction time is 1-6 h, then centrifugal, freeze-drying treatment is carried out, and a layered MXenes material is obtained. The chlorine-containing acid etchant is at least one of perchloric acid, chloric acid, chlorous acid and hypochlorous acid.

2. The method of claim 1, wherein the chlorine-containing acid etch to produce layered MXene material is characterized by, The concentration of the chlorine-containing acid etchant is 10-30 wt%.

3. The method of claim 1, wherein the chlorine-containing acid etch to produce layered MXene material is characterized by, The MAX phase material is one of Ti3AlC2, Ti2AlC, Nb2AlC, V2AlC, Cr2AlC and Ta4AlC3.

4. The method of claim 1, wherein the chlorine-containing acid etch to produce layered MXene material is characterized by, The mass ratio of the MAX phase powder to the chlorine-containing acid etchant is 1:(4-6).

5. The method of claim 1, wherein the chlorine-containing acid etch to produce layered MXene material is characterized by, The rotation speed of the centrifugal treatment is 2500-3000 rpm, and the centrifugal treatment time is 4-8 min.

6. The method of claim 1, wherein the chlorine-containing acid etch to produce layered MXene material is characterized by, The freeze-drying is carried out in a vacuum environment, and the vacuum pressure is less than or equal to 10 Pa.

7. The method of claim 1, wherein the chlorine-containing acid etch to produce layered MXene material is characterized by, The freeze-drying temperature is-90 to-100 DEG C, and the freeze-drying time is 24-48 h.

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