Method for preparing MXene two-dimensional material by gas phase etching MAX phase and application thereof

Abstract

The application belongs to the technical field of novel two-dimensional materials, and particularly relates to a method for preparing MXene two-dimensional material by gas phase etching of MAX phase and application thereof. The method for preparing MXene two-dimensional material by gas phase etching of MAX phase is disclosed, wherein MAX phase powder and etching gas precursor are placed in a sealed ampoule according to a certain molar ratio; the vacuum sealed ampoule is placed in two temperature control tube furnaces, one end of the ampoule containing the MAX phase powder and the etching gas precursor is placed in a high temperature zone, and the other end is placed in a low temperature zone; after the reaction is completed, the ampoule is naturally cooled to room temperature; and the cooled ampoule is cut to collect MXene powder obtained by etching the MAX phase powder. The simple etching step and wide application range make the method suitable for large-scale preparation, production and application of MXene.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of novel two-dimensional materials, and particularly relates to a method for preparing MXene two-dimensional material by gas phase etching of MAX phase and application thereof. BACKGROUND

[0002] As a new two-dimensional material, MXene has a very wide application prospect, such as application in battery electrodes, supercapacitor electrodes, magnetic shielding, catalytic materials and the like. It is mainly prepared by etching a precursor MAX phase, and MX elements and A layer elements are alternately combined to form a layered structure, wherein M represents early transition metal elements (such as Ti, Nb, V, Mo and the like), A represents main group elements (such as Al, Si, Ga, Sn and the like) and some transition elements (such as Zn, Cd and the like), and X represents C, N. Since the "M-A" metal bond is often weaker than the "M-X" covalent bond, the A layer element can be selectively etched to obtain a two-dimensional MXene with a general formula of M n+1 X n T x (n = 1, 2, 3), wherein Tx represents a surface functional group, and the specific element depends on the etching environment. Traditional preparation of MXene is mainly through wet etching of MAX phase, such as etching of HF acid aqueous solution which is dangerous, etching of HCl plus fluorinated salt aqueous solution, etching of halogen dissolved in organic solvent and molten salt etching and the like. Wet etching often needs to place the MAX phase in a solution or molten salt, and after etching is completed, a plurality of steps such as separation of MXene and etchant, washing, drying and the like are needed. In the etching and subsequent processing, MXene will inevitably be oxidized, which reduces its conductivity and is not conducive to the application of MXene. At the same time, in the etching process, strong etchant such as HF will inevitably etch M elements while etching A layer elements, forming M vacancies on MXene, resulting in defects in the structure of MXene, which is not conducive to the long-term stable existence of MXene. SUMMARY

[0003] In view of the prior art, the application provides a method for preparing MXene two-dimensional material by gas phase etching of MAX phase, which is simple in preparation process, does not need excessive subsequent processing steps and is not easy to be oxidized and denatured. The application has universality and is suitable for large-scale production and application, and is a high-efficiency and economical synthesis method. The MXene material prepared by the application can also be applied to multiple technical fields.

[0004] In order to solve the above technical problems, the application relates to a method for preparing MXene two-dimensional material by gas phase etching of MAX phase, comprising the following steps:

[0005] Step one, place MAX phase powder and etching gas precursor in a sealed ampoule according to a certain molar ratio, wherein the etching gas precursor needs to be additionally placed in the inner lining ampoule to isolate the MAX phase powder and the etching gas precursor, vacuum seal the ampoule containing the inner lining ampoule, and the vacuum degree is less than 5Pa during sealing;

[0006] Step two, place the vacuum sealed ampoule of step one in a two-section temperature controlled tube furnace, place the MAX phase powder and the etching gas precursor in one end of the high temperature zone, and place the other end in the low temperature zone, the heating rate is 10℃ / min, the etching time is 12-24 hours, and the reaction is naturally cooled to room temperature after the reaction is completed;

[0007] Step three, cut the cooled ampoule obtained in step two, collect the MXene powder obtained by etching the MAX phase powder.

[0008] Another object of the present application is to provide a preparation method of Ti3C2Br2 MXene powder:

[0009] Step one, place Ti3AlC2 powder and etching gas precursor CuBr2 in a sealed ampoule according to a certain molar ratio (Al:Br=1:10), wherein the etching gas precursor CuBr2 needs to be additionally placed in the inner lining ampoule to isolate the MAX phase powder and the etching gas precursor, vacuum seal the ampoule containing the inner lining ampoule, and the vacuum degree is less than 5Pa during sealing;

[0010] Step two, place the vacuum sealed ampoule of step one in a two-section temperature controlled tube furnace, place the MAX phase Ti3AlC2 powder and the etching gas precursor CuBr2 in one end of the high temperature zone (600℃), and place the other end in the low temperature zone (200℃), the heating rate is 10℃ / min, the etching time is 12 hours, and the reaction is naturally cooled to room temperature after the reaction is completed;

[0011] Step three, cut the cooled ampoule obtained in step two, collect the Ti3C2Br2 MXene powder obtained by etching the MAX phase Ti3AlC2 powder with Br2 gas (released by the etching gas precursor CuBr2).

[0012] Another object of the present application is to provide a preparation method of Ti3C2I x MXene powder, wherein,

[0013] In step one, the etching gas precursor is I2, I2 does not need to be placed in the inner lining ampoule, and the molar ratio is Al:I=1:5;

[0014] In step two, one end of the MAX phase Ti3AlC2 powder and the etching gas precursor I2 is placed in the high temperature zone (600 DEG C), and the other end is placed in the low temperature zone (300 DEG C), and the etching time is 24 hours;

[0015] In step three, the Ti3C2I MXene powder obtained by etching the MAX phase Ti3AlC2 powder with I2 gas is collected. x MXene powder.

[0016] Another object of the present application is to provide a preparation method of Ti3C2Cl2 MXene powder, wherein,

[0017] In step one, the etching gas precursor is FeCl3, and the molar ratio is Al:Cl=1:15;

[0018] In step two, one end of the MAX phase Ti3AlC2 powder and the etching gas precursor FeCl3 is placed in the high temperature zone (650 DEG C), and the other end is placed in the low temperature zone (300 DEG C);

[0019] In step three, the Ti3C2Cl2 MXene powder obtained by etching the MAX phase Ti3AlC2 powder with Cl2 gas is collected.

[0020] Another object of the present application is to provide a preparation method of Ti3C2Br2 MXene powder, wherein,

[0021] In step one, the etching gas is HBr, and the molar ratio is Al:HBr=1:5;

[0022] In step two, one end of the MAX phase Ti3AlC2 powder is placed in the high temperature zone (600 DEG C);

[0023] In step three, the Ti3C2Br2 MXene powder obtained by etching the MAX phase Ti3AlC2 powder with HBr gas is collected.

[0024] Another object of the present application is to provide a preparation method of Ti3C2I x MXene powder, wherein,

[0025] In step one, the etching gas is HI, and the molar ratio is Al:HI=1:5;

[0026] In step two, one end of the MAX phase Ti3AlC2 powder is placed in the high temperature zone (600 DEG C);

[0027] In step three, the Ti3C2I MXene powder obtained by etching the MAX phase Ti3AlC2 powder with HI gas is collected. x MXene powder.

[0028] A final objective of this invention is to provide a method for preparing Ti3C2Cl2 MXene powder, wherein,

[0029] In step one, the etching gas is HCl, and the molar ratio is Al:HCl = 1:5;

[0030] In step two, the end containing the MAX phase Ti3AlC2 powder is placed in a high-temperature zone (600°C);

[0031] In step three, Ti3C2Cl2 MXene powder was obtained by etching the MAX phase Ti3AlC2 powder with HCl gas.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] The dry etching method for preparing MXene from the MAX phase allows for the direct acquisition of solid MXene powder from solid MAX phase powder, significantly reducing subsequent processing steps in wet etching. Furthermore, byproducts are transported in the gas phase and deposited in the low-temperature region, eliminating the need for further processing and enabling separation of MXene from byproducts. Controlling the etching temperature effectively increases the stability of MXene, preventing the etching of macroelements (M) and maintaining the structural integrity of MXene. Different etchants impart different surface functional groups to MXene, resulting in diverse properties and broadening its application range. Different etching gases possess varying etching capabilities; gases with strong etching capabilities, such as Cl2 and Br2, can etch different macroelements (A) in the MAX phase, demonstrating broad applicability to MAX phase etching. Attached Figure Description

[0034] Figure 1 These are XRD patterns of Ti3C2Br2 MXene prepared in Example 1 of this invention and its precursor MAX phase Ti3AlC2;

[0035] Figure 2 yes Figure 1 Optical images of Ti3C2Br2 MXene and its precursor MAX phase Ti3AlC2 are shown.

[0036] Figure 3 yes Figure 2 The image shows a microscopic SEM image of Ti3C2Br2 MXene and its precursor MAX phase Ti3AlC2. Detailed Implementation

[0037] Example 1:

[0038] The preparation steps for Ti3C2Br2 MXene powder by Br2 vapor etching of MAX phase Ti3AlC2 powder are as follows:

[0039] Step 1: Place the MAX phase Ti3AlC2 powder and the etching gas precursor CuBr2 in a sealed ampoule with a molar ratio of Al:Br = 1:10. The etching gas precursor CuBr2 needs to be placed in an inner liner ampoule to isolate the MAX phase powder and the etching gas precursor. Vacuum seal the ampoule containing the inner liner ampoule. The vacuum level during sealing should be less than 5 Pa.

[0040] Step 2: Place the vacuum-sealed ampoule from Step 1 into a two-section temperature-controlled tube furnace. Place one end containing the MAX phase Ti3AlC2 powder and the etching gas precursor CuBr2 in the high-temperature zone (600℃) and the other end in the low-temperature zone (200℃). The heating rate is 10℃ / min, the etching time is 12 hours, and the reaction is allowed to cool naturally to room temperature after completion.

[0041] Step 3: Cut the cooled ampoule obtained in Step 2 and collect the Ti3C2Br2 MXene powder obtained by etching the MAX phase Ti3AlC2 powder with Br2 gas.

[0042] The Ti3C2Br2 MXene powder prepared in Example 1, Figure 1 The XRD patterns of the Ti3C2Br2 MXene powder and its precursor, the MAX phase Ti3AlC2 powder, are shown. The characteristic peaks of the MAX phase Ti3AlC2 powder disappeared after etching, indicating that the Al element was completely etched. Furthermore, the (004) peak of the Ti3C2Br2 MXene powder shifted to the left relative to Ti3AlC2, indicating that the presence of Br surface functional groups increased the interlayer spacing between MXenes. Figure 2 In optical images, the MAX phase Ti3AlC2 powder appears gray, while the MXene obtained after etching turns black and becomes more fluffy, which is one of the macroscopic signs of successful MXene preparation; Figure 3 In the microscopic SEM images, the dense layered structure of the MAX phase Ti3AlC2 transforms into the classic "accordion"-shaped, separated layered structure of MXene after etching. The porous layered structure is also the reason why MXene appears fluffy on a macroscopic scale. The effectiveness of this etching method can be demonstrated by XRD, macroscopic optical images, and SEM images.

[0043] Example 2:

[0044] The preparation process is basically the same as in Example 1, except that: in step one, the etching gas precursor is I2, which does not need to be placed in the inner liner ampoule, and the molar ratio is Al:I = 1:5; in step two, one end containing the MAX phase Ti3AlC2 powder and the etching gas precursor I2 is placed in the high-temperature zone (600°C), and the other end is placed in the low-temperature zone (300°C), and the etching time is 24 hours; in step three, the Ti3C2I obtained by etching the MAX phase Ti3AlC2 powder with I2 gas is collected. x MXene powder.

[0045] Example 3:

[0046] The preparation process is basically the same as in Example 1, except that: in step one, the etching gas precursor is FeCl3, and the molar ratio is Al:Cl = 1:15; in step two, one end of the MAX phase Ti3AlC2 powder and the etching gas precursor FeCl3 is placed in the high temperature zone (650°C), and the other end is placed in the low temperature zone (300°C); in step three, the Ti3C2Cl2MXene powder obtained by etching the MAX phase Ti3AlC2 powder with Cl2 gas is collected.

[0047] Example 4:

[0048] The preparation process is basically the same as in Example 1, except that: in step one, the etching gas is HBr and the molar ratio is Al:HBr = 1:5; in step two, the end containing the MAX phase Ti3AlC2 powder is placed in a high-temperature zone (600°C); in step three, the Ti3C2Br2 MXene powder obtained by etching the MAX phase Ti3AlC2 powder with HBr gas is collected.

[0049] Example 5:

[0050] The preparation process is basically the same as in Example 1, except that: in step one, the etching gas is HI, and the molar ratio is Al:HI = 1:5; in step two, one end containing the MAX phase Ti3AlC2 powder is placed in a high-temperature zone (600°C); in step three, the Ti3C2I obtained by etching the MAX phase Ti3AlC2 powder with HI gas is collected. x MXene powder.

[0051] Example 6:

[0052] The preparation process is basically the same as in Example 1, except that: in step one, the etching gas is HCl and the molar ratio is Al:HCl = 1:5; in step two, the end containing the MAX phase Ti3AlC2 powder is placed in a high-temperature zone (600°C); in step three, the Ti3C2Cl2 MXene powder is obtained by collecting HCl gas to etch the MAX phase Ti3AlC2 powder.

[0053] Example 7:

[0054] The preparation process is basically the same as in Example 1, except that: in step one, the etching gas precursor is FeCl3, and the molar ratio is Al:Cl = 1:15; in step two, one end of the MAX phase Ti3SiC2 powder and the etching gas precursor FeCl3 is placed in the high temperature zone (650°C), and the other end is placed in the low temperature zone (300°C); in step three, the Ti3C2Cl2MXene powder obtained by etching the MAX phase Ti3SiC2 powder with Cl2 gas is collected.

[0055] As can be summarized from the above embodiments, when prepared according to the process shown in the claims, different MAX phases can be etched with different gases to obtain the corresponding MXene materials. The above embodiments mainly list different etching gases, which mainly include I2, Br2, Cl2, HI, HBr, and HCl. The MAX phases to be etched include, but are not limited to, Ti3AlC2 and Ti3SiC2, as well as Ti2AlC, Ti3GeC2, Ti3GaC2, Ti3InC2, Ti3SnC2, and non-Ti-based MAX phases.

[0056] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing MXene two-dimensional materials by vapor etching of MAX phase, characterized in that, Includes the following steps: Step 1: Place the MAX phase and etching gas or etching gas precursor in a sealed ampoule and vacuum seal the ampoule; the MAX phase includes: Ti3AlC2, and also includes Ti2AlC, Ti3SiC2, Ti3GeC2, Ti3GaC2, Ti3InC2, Ti3SnC2 and non-Ti-based MAX phases; When the MAX phase is Ti3AlC2 powder and the etching gas precursor is CuBr2, the molar ratio Al:Br = 1:10; When the MAX phase is Ti3AlC2 powder and the etching gas precursor is I2, I2 does not need to be placed in the inner liner ampoule, and the molar ratio is Al:I = 1:5; When the MAX phase is Ti3AlC2 powder, the etching gas precursor is FeCl3, and the molar ratio is Al:Cl = 1:15; When the MAX phase is Ti3AlC2 powder, the etching gas is HBr, and the molar ratio is Al:HBr=1:5; When the MAX phase is Ti3AlC2 powder, the etching gas is HI, and the molar ratio is Al:HI = 1:5; When the MAX phase is Ti3AlC2 powder, the etching gas is HCl, and the molar ratio is Al:HCl = 1:5; Step 2: Place the vacuum-sealed ampoule from Step 1 into a two-section temperature-controlled tube furnace. Place one end containing the MAX phase and the etching gas precursor in the high-temperature zone and the other end in the low-temperature zone to allow byproducts to be transported to the low-temperature zone via the gas phase. After the etching reaction is complete, allow the temperature to cool naturally to room temperature. The temperature of the high-temperature zone is 600–650°C, and the temperature of the low-temperature zone is 200–300°C. Step 3: Cut the cooled ampoule obtained in Step 2 and collect the MXene two-dimensional material powder.

2. The method according to claim 1, characterized in that, The etching gas mentioned in step one includes: Br2, I2, Cl2, HBr, HI or HCl.

3. The method according to claim 1, characterized in that, The etching gas precursor mentioned in step one includes CuBr2 or FeCl3.

4. The method according to claim 1, characterized in that, The etching gas precursor described in step one needs to be placed in an inner-lined ampoule to isolate the MAX phase powder and the etching gas precursor.

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