Etching method of layered structure MXene and MXene
By using molten alkali etching MAX, the safety and environmental risks of HF in existing MXene preparation and the impact of F-functional groups are solved, and the fluorine-free, fast and low-temperature MXene preparation is achieved, and the product has good physical properties.
Patent Information
- Application Number
- CN202510088194.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-20
- Publication Date
- 2025-05-16
AI Technical Summary
The use of toxic and corrosive HF in existing MXene preparation methods leads to human safety and environmental risks, and the MXene surface prepared by wet chemical etching methods contains a large number of F-functional groups, affecting its application in biomedical and batteries.
The method of etching MAX in molten alkali is used to produce MXene. The layered structure MXene is prepared by placing the alkali into a crucible and melting it and stirring it with MAX powder to react to selectively etch the aluminum layer.
The preparation of MXene without fluorine is achieved, with short etching time, low temperature, fast production speed, large output, and the layered structure of the product is long and narrow, and the layers are clearly divided, avoiding the phenomenon of stacking between layers and having good physical properties.
Smart Images
Figure CN120004276A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of chemical preparation, and in particular to an etching method for layered MXene and MXene. Background Art
[0002] In the past decade, two-dimensional materials (2D) MXene have attracted the research interests of researchers in various fields. MXene has the advantages of excellent metallic conductivity, hydrophilicity, easy processing, and relatively high yield. These characteristics make it stand out from many 2D materials and become a promising candidate for energy storage, electromagnetic absorption, catalysis and sensor applications. MXene is obtained by etching MAX, which is a layered carbide or nitride with a general formula of M n+1 AX n (n=1-4). "M" represents early transition metals (such as Ti, V), "A" mainly includes IIIA and IVA group elements such as Al and Si, and "X" is C or N. The general formula of MXene is M n+1 X n They are produced by selectively etching the "A" element from the MAX phase of a layered ceramic material. If the MAX is Ti2AlC, the etched MXene is Ti2C.
[0003] In general, MX bonds provide ionic and covalent properties, showing higher binding energy than MA bonds. Therefore, MA bonds in MAX are easier to break than MX bonds. However, due to the presence of MA bonds, mechanical exfoliation of MXene from the bulk MAX phase is difficult. The synthesis of common MXenes is based on selective etching of the A layer of the corresponding MAX phase in HF solution or forming an in situ HF solution. However, these methods pose significant risks to human safety and the environment due to the formation of toxic and corrosive HF; in addition, the surface of the synthesized MXene prepared by wet chemical etching contains a large amount of F - Functional groups affect their applications in biomedicine and batteries. Therefore, it is urgent to explore fluorine-free methods for the preparation of MXenes.
[0004] Fluorine-free methods have been reported, such as HCl hydrothermal method, Lewis acid molten salt etching method, electrochemical etching method, chemical vapor deposition method, ball milling method, tip ultrasound method, etc. Most of these methods have long reaction time, small yield and low synthesis efficiency. Summary of the invention
[0005] In view of the above technical problems, the present invention provides a method for producing MXene by molten alkali etching MAX, and can achieve the large-scale preparation of layered MXene. The present invention uses molten alkali etching to synthesize MXene in a simple and controllable manner, and the preparation method can be suitable for mass production in factories.
[0006] The technical solution of the present invention is as follows:
[0007] A method for etching a layered MXene structure, using molten alkali as an etchant, comprising the following steps:
[0008] Put the alkali into the crucible and heat it to melt it into molten alkali;
[0009] After melting to reaction temperature, add MAX powder and stir;
[0010] After a certain reaction time, stop heating;
[0011] The reactants are washed, filtered and dried to obtain MXene.
[0012] The present invention uses MAX as a precursor and molten alkali as an etchant to prepare layered MXene by selectively etching the aluminum layer in MAX with alkali.
[0013] The reaction mechanism is as follows: (taking sodium hydroxide etching Ti2AlC as an example)
[0014] Molten sodium hydroxide exhibits strong alkalinity and strong corrosiveness, and can react with highly reducing amphoteric active metal aluminum. When Ti2AlC reacts with molten sodium hydroxide, OH in the molten state - The Ti-Al bond is destroyed, aluminum loses electrons to become aluminum ions (a small amount of titanium is oxidized to titanate), and the hydrogen in the sodium hydroxide gains electrons to generate hydrogen. Unlike aqueous solution systems, high-temperature melting conditions overcome the kinetic barriers of the reaction, and aluminum ions combine with oxygen to form stable aluminate ions. Since sodium ions are present in large quantities in the molten state, aluminate ions combine with sodium ions to form Na3AlO3. The highly fluid molten sodium hydroxide can fully penetrate the Al atomic layer in the MAX phase and etch away the Al atoms from the interlayer; the generated H2 can effectively expand the interlayer spacing and increase the reaction sites of Al. This enables the molten alkali etching method of the present invention to rapidly etch the Ti2AlC MAX phase into Ti2C MXene with a wide interlayer spacing without fluorine within 30 minutes.
[0015] The etching method further comprises the step of multiple etchings, wherein the multiple etchings use the product of the previous etching as a raw material to repeat steps 3 to 4. The morphology of the product after etching twice or three times is better.
[0016] It should be noted that there are many kinds of alkalis for etching MAX, and the alkali is a mixture of one or more strong alkalis, and the strong alkali may be lithium hydroxide, sodium hydroxide, potassium hydroxide, and the purity of the alkali is not less than 95%.
[0017] MAX is carbon aluminum titanium, such as Ti2AlC, Ti3AlC2.
[0018] The temperature of the etching reaction is 200° C. to 1000° C. Preferably, the temperature of the etching reaction is 200° C. to 600° C.
[0019] The etching reaction time is 1 min to 2 h. The etching degree and etching rate of MXene can be regulated by controlling the etching temperature and time.
[0020] The washing includes water washing and acid washing. Specifically, the reactants are washed, filtered, and dried by transferring the reactants to a beaker (preferably a polytetrafluoroethylene beaker) and dripping deionized water, which can quickly dissolve the reactants into a solution; the solution is filtered to separate the target product from the alkali solution and the aluminum salt; the particles obtained by filtering the solution are washed with acid to wash away the aluminum oxide salt remaining between the MAX layers, thereby obtaining a MXene with an accordion structure.
[0021] The pickling agent is concentrated hydrochloric acid (36wt%-38wt%) and its dilution, and the pickling time is 5min-3h.
[0022] The reaction process also includes the step of stirring or blowing the reactants. Adequate stirring or blowing during the etching process can enhance the kinetic conditions of the etching process and remove the aluminum oxide salt from the MAX surface in a timely manner.
[0023] The mass ratio of the alkali to the MAX powder is 1:1 to 100:1. Preferably, the mass ratio of the alkali to the MAX powder is 10:1 to 100:1.
[0024] The beneficial effects of the present invention are:
[0025] (1) Compared with the existing preparation methods, the preparation method of the present invention does not involve fluorine, has a short etching time, a low etching temperature, a fast production speed, and simpler production equipment. Alkali and MAX can be heated in an open environment, without the need for vacuum or argon atmosphere, and the production conditions are simple; the time required for molten alkali etching is short, and a layered MXene can be obtained after etching for 5 minutes.
[0026] (2) The layered structure of the product MXene is long and narrow in depth, with clear separation between layers, avoiding the interlayer stacking phenomenon of traditional MXene, that is, the existence of a few-layer MAX, and the product has good physical properties.
[0027] (3) The preparation method of the present invention can realize the large-scale preparation of MXene, which is conducive to scientific research promotion and industrialization. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 This is the SEM image of the original MAX (Ti2AlC) of Example 1.
[0029] Figure 2 This is the SEM image of the layered MXene (Ti2C) obtained in Example 1.
[0030] Figure 3 This is the XRD diagram of the sample in Example 1 before and after etching.
[0031] Figure 4 This is the SEM image of the layered MXene (Ti2C) obtained in Example 2.
[0032] Figure 5 This is the SEM image of the layered MXene (Ti2C) obtained in Example 3.
[0033] Figure 6 This is the SEM image of the layered MXene (Ti2C) obtained in Example 4.
[0034] Figure 7 This is the SEM image of the layered MXene (Ti3C2) obtained in Example 5.
[0035] Figure 8 This is the SEM image of Ti3C2 obtained by alkaline hydrothermal etching method.
[0036] Fig. 9 This is the SEM image of Ti3C2 obtained by Lewis acid molten salt etching method. DETAILED DESCRIPTION
[0037] Embodiment 1
[0038] This embodiment is implemented by using an electric heating jacket, which can provide a stable and controllable heating rate.
[0039] A method for etching layered MXene (Ti2C), comprising the following steps:
[0040] (1) Accurately weigh 20.833 g of sodium hydroxide particles and 29.166 g of potassium hydroxide particles (molar ratio of 1:1), grind and mix them, and place them in a 100 mL nickel crucible. Then, place the nickel crucible in an electric heating mantle.
[0041] (2) The temperature of the electric heating mantle is set to 300°C and heated for 30 minutes to melt the mixed alkali into a transparent molten salt.
[0042] (3) Accurately weigh 0.5 g of MAX (Ti2AlC) and add it to the molten salt surface while stirring continuously. After the addition of MAX (Ti2AlC), stop heating after etching for 30 min.
[0043] (4) After the reaction is completed, the molten salt in the nickel crucible is poured into a polytetrafluoroethylene beaker, and a small amount of deionized water is added to quickly dissolve the molten salt into an aqueous solution to prevent the molten salt from cooling and forming a hard lump.
[0044] (5) Filter the mixed solution to remove the alkali solution and part of the aluminum salt. After repeated water washing and filtration for several times, the product was placed in a beaker containing 20 mL of concentrated hydrochloric acid for acid washing and stirred for 2 h.
[0045] (6) The acid-washed product was filtered, and the water washing and filtration were repeated several times, and the product was dried at 80°C for 12 hours.
[0046] Figure 1 This is the SEM picture of the original MAX (Ti2AlC) etched in Example 1. Figure 1 It can be seen that MAX (Ti2AlC) is a compact block when not etched.
[0047] Figure 2 This is a SEM image of the product MXene (Ti2C) of Example 1. Figure 2 It can be seen that the obtained MXene (Ti2C) layers are separated like a blade without stacking, which indicates that the aluminum layer in the original MAX (Ti2AlC) is selectively etched away.
[0048] Figure 3 This is the XRD image of the sample of Example 1 before and after etching. The peak intensity ratio 002 peak / 103 peak is significantly reduced after the etching reaction, which further proves that the molten alkali selectively etches MAX (Ti2AlC).
[0049] Embodiment 2
[0050] This embodiment is implemented by using an electric heating jacket, which can provide a stable and controllable heating rate.
[0051] A method for etching layered MXene (Ti2C), comprising the following steps:
[0052] (1) Accurately weigh 20.833 g of sodium hydroxide particles and 29.166 g of potassium hydroxide particles (molar ratio of 1:1), grind and mix them, and place them in a 100 mL nickel crucible. Then, place the nickel crucible in an electric heating mantle.
[0053] (2) The temperature of the electric heating mantle is set to 300°C and heated for 30 minutes to melt the mixed alkali into a transparent molten salt.
[0054] (3) Accurately weigh 0.5 g of MAX (Ti2AlC) and add it to the molten salt surface while stirring continuously. After the addition of MAX (Ti2AlC), stop heating after etching for 10 min.
[0055] (4) After the reaction is completed, the molten salt in the nickel crucible is poured into a polytetrafluoroethylene beaker, and a small amount of deionized water is added to quickly dissolve the molten salt into an aqueous solution to prevent the molten salt from cooling and forming a hard lump.
[0056] (5) Filter the mixed solution to remove the alkali solution and part of the aluminum salt. After repeated water washing and filtration for several times, the product was placed in a beaker containing 20 mL of concentrated hydrochloric acid for acid washing and stirred for 30 minutes.
[0057] (6) The acid-washed product was filtered, and the water washing and filtration were repeated several times, and the product was dried at 80°C for 12 hours.
[0058] Figure 4 is the SEM image of Example 2. Figure 4 It can be seen that the synthesized MXene (Ti2C) has an obvious layered structure, like rows of blades closely arranged together, because the aluminum layer in the original MAX (Ti2AlC) is selectively etched. At the same time, this embodiment achieves rapid etching of MXene (Ti2C) (10 minutes), which is faster than the existing etching methods.
[0059] The etchant base can be a mixture of sodium hydroxide and potassium hydroxide (molar ratio = 1:1), so that the melting point of the mixture is low and the required heating equipment is simple.
[0060] Embodiment 3
[0061] This embodiment is implemented by using an electric heating jacket, which can provide a stable and controllable heating rate.
[0062] A method for etching layered MXene (Ti2C), comprising the following steps:
[0063] (1) Accurately weigh 20.833 g of sodium hydroxide particles and 29.166 g of potassium hydroxide particles (molar ratio of 1:1), grind and mix them, and place them in a 100 mL nickel crucible. Then, place the nickel crucible in an electric heating mantle.
[0064] (2) The temperature of the electric heating mantle is set to 300°C and heated for 30 minutes to melt the mixed alkali into a transparent molten salt.
[0065] (3) Accurately weigh 0.5 g of 500 mesh MAX (Ti2AlC), add it to the molten salt surface, and stir continuously. Start from the addition of MAX (Ti2AlC), and stop heating after etching for 10 minutes.
[0066] (4) After the reaction is completed, the molten salt in the nickel crucible is poured into a polytetrafluoroethylene beaker, and a small amount of deionized water is added to quickly dissolve the molten salt into an aqueous solution to prevent the molten salt from cooling and forming a hard lump.
[0067] (5) Filter the mixed solution to remove the alkali solution and part of the aluminum salt. After repeated water washing and filtration for several times, the product was placed in a beaker containing 20 mL of concentrated hydrochloric acid for acid washing and stirred for 30 minutes.
[0068] (6) The acid-washed product was filtered, and the water washing and filtration were repeated several times, and the product was dried at 80°C for 12 hours.
[0069] (7) The product obtained in (6) is used as the precursor in (3) for secondary etching, and steps (1) to (6) are repeated.
[0070] Figure 5 is the SEM image of Example 3. Figure 5 It can be seen that after the original MAX (Ti2AlC) undergoes two etching processes, the obtained MXene (Ti2C) has a wider interlayer spacing, which will increase the specific surface area of MXene and is beneficial to improving the electrochemical performance of MXene-based electrodes.
[0071] Embodiment 4
[0072] This embodiment is implemented using a resistance heating stage, which can provide a relatively high heating temperature in an open air environment.
[0073] A method for etching layered MXene (Ti3C2), comprising the following steps:
[0074] (1) Accurately weigh 25 g of sodium hydroxide particles, grind them and place them in a 100 mL nickel crucible, which is then placed on a resistance heating table.
[0075] (2) The heating temperature of the electric heating jacket is set to 600° C. and heated for 30 minutes to melt the mixed alkali into a transparent molten salt.
[0076] (3) Accurately weigh 0.5 g of MAX (Ti2AlC) and add it to the molten salt surface while stirring continuously. After the addition of Ti2AlC, stop heating after etching for 2 h.
[0077] (4) After the reaction is completed, the molten salt in the nickel crucible is poured into a polytetrafluoroethylene beaker, and a small amount of deionized water is added to quickly dissolve the molten salt into an aqueous solution to prevent the molten salt from cooling and forming a hard lump.
[0078] (5) Filter the mixed solution to remove the alkali solution and part of the aluminum salt. After repeated water washing and filtration for several times, the product was placed in a beaker containing 20 mL of concentrated hydrochloric acid for acid washing and stirred for 2 h.
[0079] (6) The acid-washed product was filtered, and the water washing and filtration were repeated several times, and the product was dried at 80°C for 12 hours.
[0080] Figure 6 is the SEM image of Example 4. Figure 6 It can be seen that etching MAX(Ti2AlC) only with molten sodium hydroxide can also obtain blade-like layered MXene(Ti2C).
[0081] Embodiment 5
[0082] This embodiment is implemented using a resistance heating stage, which can provide a relatively high heating temperature in an open air environment.
[0083] A method for etching layered MXene (Ti3C2), comprising the following steps:
[0084] (1) Accurately weigh 20 g of sodium hydroxide particles, grind them and place them in a 100 mL nickel crucible, which is then placed on a resistance heating table.
[0085] (2) The heating temperature of the electric heating jacket is set to 500° C. and heated for 30 minutes to melt the mixed alkali into a transparent molten salt.
[0086] (3) Accurately weigh 0.3 g of MAX (Ti3AlC2) and add it to the molten salt surface while stirring continuously. From the time MAX (Ti3AlC2) is added, the heating is stopped after etching for 2 h.
[0087] (4) After the reaction is completed, the molten salt in the nickel crucible is poured into a polytetrafluoroethylene beaker, and a small amount of deionized water is added to quickly dissolve the molten salt into an aqueous solution to prevent the molten salt from cooling and forming a hard lump.
[0088] (5) The mixed solution was filtered to remove the alkali solution and part of the aluminum salt. After repeated water washing and filtration for several times, the product was placed in a beaker containing 20 mL of 3M hydrochloric acid for acid washing and stirred for 2 h.
[0089] (6) The acid-washed product was filtered, and the water washing and filtration were repeated several times, and the product was dried at 80°C for 12 hours.
[0090] Figure 7 It is the SEM image of Example 5. Figure 6 It can be seen that only by etching the 312-type MAX phase (Ti3AlC2) with molten sodium hydroxide, a layered structure MXene (Ti3C2) arranged like a blade can also be obtained.
[0091] Embodiment 6
[0092] This embodiment is implemented by using an electric heating jacket, which can provide a stable and controllable heating rate.
[0093] A method for etching layered MXene (Ti2C), comprising the following steps:
[0094] (1) Accurately weigh 29.41 g of sodium hydroxide particles and 20.58 g of potassium hydroxide particles (molar ratio of 2:1), grind and mix them, and place them in a 200 mL nickel crucible. Then, place the nickel crucible in an electric heating mantle.
[0095] (2) The temperature of the electric heating mantle is set to 200°C and heated for 60 minutes to melt the mixed alkali into a transparent molten salt.
[0096] (3) Accurately weigh 0.5 g of MAX (Ti2AlC) and add it to the molten salt surface while stirring continuously. After the addition of MAX (Ti2AlC), etch for 1 min before stopping heating.
[0097] (4) After the reaction is completed, the molten salt in the nickel crucible is poured into a polytetrafluoroethylene beaker, and a small amount of deionized water is added to quickly dissolve the molten salt into an aqueous solution to prevent the molten salt from cooling and forming a hard lump.
[0098] (5) The mixed solution was filtered to remove the alkali solution and part of the aluminum salt. After repeated water washing and filtration for several times, the product was placed in a beaker containing 20 mL of 3M hydrochloric acid for acid washing and stirred for 2 h.
[0099] (6) The acid-washed product was filtered, and the water washing and filtration were repeated several times, and the product was dried at 80°C for 12 hours.
[0100] Embodiment 7
[0101] This embodiment is implemented by using an electric heating jacket, which can provide a stable and controllable heating rate.
[0102] A method for etching layered MXene (Ti2C), comprising the following steps:
[0103] (1) 41.666 g of sodium hydroxide particles and 58.332 g of potassium hydroxide particles (molar ratio of 1:1) were accurately weighed, ground and mixed, and placed in a 200 mL nickel crucible, which was then placed in an electric heating mantle.
[0104] (2) The temperature of the electric heating mantle is set to 300°C and heated for 60 minutes to melt the mixed alkali into a transparent molten salt.
[0105] (3) Accurately weigh 10 g of MAX (Ti2AlC), add it to the molten salt surface, and stir continuously. Start from the addition of MAX (Ti2AlC), and stop heating after etching for 30 minutes.
[0106] (4) After the reaction is completed, the molten salt in the nickel crucible is poured into a polytetrafluoroethylene beaker, and a small amount of deionized water is added to quickly dissolve the molten salt into an aqueous solution to prevent the molten salt from cooling and forming a hard lump.
[0107] (5) Filter the mixed solution to remove the alkali solution and part of the aluminum salt. After repeated water washing and filtration for several times, the product was placed in a beaker containing 20 mL of concentrated hydrochloric acid for acid washing and stirred for 2 h.
[0108] (6) The acid-washed product was filtered, and the water washing and filtration were repeated several times, and the product was dried at 80°C for 12 hours.
[0109] Comparative Example 1
[0110] This comparative example adopts alkaline solution hydrothermal etching method. The specific steps are as follows:
[0111] (1) Deionized water was heated to boiling and stored in argon for 30 minutes. Then, 110 g of NaOH was added to 100 mL of water to obtain a 27.5 mol / L NaOH aqueous solution.
[0112] (2) 100 mg of Ti3AlC2 powder was added to 25 ml of NaOH solution in a 50 ml autoclave. After the air was evacuated by flowing argon, the autoclave was sealed.
[0113] (3) Heat the autoclave at 270°C in an electric constant temperature drying oven for 12 hours.
[0114] (4) After the hydrothermal process, the resulting suspension was separated into two layers. The upper layer was a transparent solution and the lower layer was a black suspension. After filtering with a PVDF filter membrane with a pore size of 0.1 μm, it was rinsed with deionized water several times. x The powder extracted from the residue was dried in a vacuum oven at 65 °C for 12 h.
[0115] (5) Using this method, about 80 to 90 mg of Ti3C2T can be obtained from 100 mg of Ti3AlC2 powder. x +Ti3AlC2+TiO2 mixture.
[0116] Comparative Example 2
[0117] This embodiment adopts Lewis acid molten salt etching.
[0118] Taking CuCl2 Lewis acid molten salt as an example, the molten CuCl2 etching method includes the following steps:
[0119] (1) 1 g Ti3AlC2 MAX phase powder was mixed with 2.1 g CuCl2 powder (molar ratio 1:3) and ground for 10 min. Then 0.6 g NaCl and 0.76 g KCl were added and ground for another 10 min.
[0120] (2) The mixture was placed in an alumina porcelain boat, and then the porcelain boat was placed in a tube furnace filled with argon gas, and the powder mixture was heated to 750°C at a heating rate of 4°C min -1 , keep warm for 24 hours.
[0121] (3) The obtained product was washed with deionized water to remove excess chloride salts to obtain MXene / Cu mixed particles, and then the MXene / Cu mixture was washed with 0.1 M APS solution to remove residual Cu particles.
[0122] (4) The obtained solution was washed with deionized water and alcohol for 5 times, and filtered with a microfiltration membrane.
[0123] (5) The MXene powder was vacuum dried at room temperature for 24 h.
[0124] Figure 8 This is the SEM image of Ti3C2 obtained by alkaline hydrothermal etching method. Fig. 9 This is the SEM image of Ti3C2 obtained by Lewis acid molten salt etching. Figure 2 , Figure 8 and Fig. 9 It can be seen that the etching product of the present invention is more uniform and has a more uniform interlayer spacing than the comparative example, while the interlayer spacings of comparative examples 1 and 2 are less consistent in comparison.
[0125] In addition, the molten alkali etching time of the present invention is also short, as shown in the following table:
[0126]
[0127] It can be seen from the above table that, compared with alkaline solution etching and Lewis acid molten salt etching, the etching time of the molten alkali of the present invention is very short.
[0128] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the claims.
Claims
1. A method for etching a layered MXene, characterized in that: Using molten alkali as the etchant, The steps include: Step 1: heating and melting the alkali to make it into molten alkali; Step 2: After melting to the reaction temperature, add MAX powder and stir; Step 3: After a certain reaction time, stop heating; Step 4: Wash, filter and dry the reactants to obtain MXene.
2. The etching method according to claim 1, characterized in that: The etching method further comprises the steps of multiple etchings, wherein the multiple etchings are performed by repeating steps 3 to 4 using the product of the previous etching as a raw material.
3. The etching method according to claim 1, characterized in that: The washing includes water washing and pickling. The pickling agent used in the pickling is concentrated hydrochloric acid and its dilution. The pickling time is 5 minutes to 3 hours.
4. The etching method according to claim 1, characterized in that: MAX is carbon aluminum titanium; the base is a mixture of one or more strong bases.
5. The etching method according to claim 4, characterized in that: The alkali is a mixture of sodium hydroxide and potassium hydroxide.
6. The etching method according to claim 5, characterized in that: The molar ratio of the sodium hydroxide to the potassium hydroxide is 1:
1.
7. The etching method according to claim 1, characterized in that: The reaction temperature is 200° C. to 1000° C.; the reaction time is 1 min to 2 h.
8. The etching method according to claim 1, characterized in that: The reaction process also includes the step of stirring or blowing the reactants.
9. The etching method according to claim 1, characterized in that: The mass ratio of base to MAX powder is 1:1 to 100:
1.
10. MXene obtained by the etching method of layered MXene according to any one of claims 1 to 9.