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CN-121974349-A - Preparation method of MXene by physical puffing stripping chemical etching

CN121974349ACN 121974349 ACN121974349 ACN 121974349ACN-121974349-A

Abstract

The invention discloses a preparation method of MXene by physical puffing and stripping chemical etching, which comprises the steps of placing a MAX phase precursor in a supercritical reaction kettle, introducing carbon dioxide, regulating temperature and pressure to enable the carbon dioxide to reach a supercritical state for physical puffing, stirring at constant temperature and constant pressure for a certain time, performing physical puffing and pressure relief treatment, repeating the physical puffing and pressure relief operation for n times, placing a product obtained after the physical puffing treatment, a fluorine-free etching agent and an auxiliary agent into the supercritical reaction kettle together, introducing the carbon dioxide again, regulating temperature and pressure to enable the carbon dioxide to maintain the supercritical state, simultaneously performing supercritical etching reaction for a preset period of time in a stirring or fluid circulation mode, performing instantaneous blasting treatment on a reaction system after the supercritical etching reaction is completed, taking out a reaction product, and washing to be neutral to obtain the target MXene. The invention improves the effect of chemical etching, shortens the chemical reaction time and reduces the dosage of chemicals.

Inventors

  • ZHANG HENGYU
  • LONG JIAJIE

Assignees

  • 苏州大学

Dates

Publication Date
20260505
Application Date
20260126

Claims (10)

  1. 1. A preparation method of MXene by physical puffing stripping chemical etching is characterized by comprising the following steps: (1) Placing MAX phase precursor in a supercritical reaction kettle, introducing carbon dioxide, regulating and controlling to a set temperature and pressure to enable the carbon dioxide to reach a supercritical state for physical puffing and stripping, stirring at constant temperature and constant pressure for a certain time, and then carrying out physical puffing and pressure relief treatment, wherein the physical puffing and pressure relief operation is repeated for n times, and n is an integer greater than or equal to 2, so as to obtain a product after the physical puffing treatment; (2) Putting the physically puffed product obtained in the step (1) and a fluorine-free etchant into a supercritical reaction kettle, introducing carbon dioxide again, regulating and controlling the temperature and the pressure to maintain the carbon dioxide in a supercritical state, and simultaneously carrying out supercritical etching reaction for a preset period of time in a stirring or fluid circulation mode; (3) After the supercritical etching reaction is completed, carrying out instantaneous blasting stripping treatment on the reaction system; (4) And taking out the reaction product, and washing the reaction product to be neutral to obtain the target MXene.
  2. 2. The method for preparing the MXene by physical puffing peeling chemical etching according to claim 1, wherein n in the step (1) is 2-6.
  3. 3. The method for preparing MXene by physical puffing peeling chemical etching according to claim 1, wherein the MAX phase is Ti 3 AlC 2 、Nb 2 AlC、Ti 2 AlC、Mo 2 GaC、Ti 3 AlCN or V 2 AlC.
  4. 4. The method for preparing the MXene by physical puffing peeling chemical etching according to claim 1, wherein the temperature set in the step (1) is 32-150 ℃, the pressure is 8-30 mpa, and the stirring time is 1-10 h.
  5. 5. The method for preparing MXene by physical puffing stripping chemical etching according to claim 1, wherein the fluorine-free etching agent in the step (2) is inorganic base or organic base, the inorganic base is sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonium hydroxide, barium hydroxide, magnesium hydroxide, ammonium hydroxide, sodium carbonate or potassium carbonate, and the organic base is one or more of tetramethylammonium hydroxide, tetrabutylammonium hydroxide, tetraethylammonium hydroxide, methylamine, ethylamine, dimethylamine, triethylamine, ethylenediamine and hexamethylenediamine.
  6. 6. The method for preparing the MXene by physical puffing stripping chemical etching according to claim 1, wherein the fluorine-free etching agent in the step (2) is inorganic acid or organic acid, the inorganic acid is hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, perchloric acid or carbonic acid, and the organic acid is one or more of oxalic acid, formic acid and acetic acid.
  7. 7. The method for preparing the MXene physical puffing stripping chemical etching according to claim 5 or 6, wherein the mass ratio of the fluorine-free etching agent to the MAX phase is 50:1-10:1.
  8. 8. The method for preparing the MXene by physical puffing stripping chemical etching according to claim 1, wherein the temperature in the step (2) is 32-150 ℃, the pressure is 7.4-30 Mpa, the stirring speed is 400-10000rpm, and the preset time period is 1-48 h.
  9. 9. The method for preparing the MXene by physical puffing stripping chemical etching is characterized in that in the step (2), the MXene and a product after physical puffing treatment are placed into a supercritical reaction kettle together, and an auxiliary agent is added, wherein the auxiliary agent is one or more of water, ethanol, methanol, isopropanol, hydrogen peroxide, dimethyl sulfoxide and acetone, and the mass ratio of the fluorine-free etching agent to the auxiliary agent is 15-80:100.
  10. 10. The method of claim 1, wherein the pressure of the instantaneous burst peeling in the step (3) is 7.4MPa to 30MPa.

Description

Preparation method of MXene by physical puffing stripping chemical etching Technical Field The invention belongs to the technical field of two-dimensional nano material preparation, and particularly relates to a preparation method of MXene by physical puffing and stripping chemical etching. Background MXene is used as a two-dimensional transition metal carbon/nitrogen compound, has the advantages of high conductivity, hydrophilicity, adjustable surface chemical characteristics and the like, and has great application potential in the fields of energy storage, environmental management, flexible electronics and the like. However, the current mainstream preparation process seriously depends on fluorine-containing etchants such as hydrofluoric acid, ammonium bifluoride, ammonium fluoride, lithium fluoride and the like, and has the inherent defects of high toxicity, high corrosiveness, high environmental risk and the like. The method not only ensures poor safety in the production process, but also introduces a large number of fluorine terminals on the surface of the material, so that the conductivity of MXene is reduced, the electrochemical performance is attenuated, oxidation failure is easy to occur in the aqueous solution, and the exertion of the intrinsic performance and the practical application expansion of the material are obviously restricted. Therefore, the development of safe, green fluorine-free manufacturing techniques is critical to the development of MXene. In the prior art, various fluorine-free preparation routes such as electrochemical etching, an alkaline heating method and a molten salt method have been explored, but obvious limitations exist, the patent CN114477181A proposes to prepare MXene in a supercritical carbon dioxide system in a large scale, but the etchant used by the method is ammonium bifluoride, fluorine-containing byproducts are still generated, the fluorine dependence is not thoroughly eliminated, the patent CN114031078A, CN116588940A adopts solid alkali or molten salt to prepare fluorine-free MXene, the reaction is required to be carried out under the high temperature condition of more than 300 ℃, the energy consumption and the process difficulty are increased, and the patent CN114316971A discloses a preparation method of fluorine-free MXene quantum dots, but the process can destroy the intrinsic structural characteristics of the MXene and lose the original performance advantages. In summary, developing a fluorine-free preparation technology with low cost and large scale has become a key requirement for promoting the green industrialization development of MXene. Disclosure of Invention Aiming at the technical problems, the invention provides a preparation method of MXene by physical puffing stripping chemical etching, which etches MAX phase precursors by adopting supercritical carbon dioxide fluid carrying fluorine-free etchant, and combines pretreatment and aftertreatment of instantaneous explosion pressure relief, thereby greatly improving the stripping efficiency of MXene and realizing fluorine-free high-efficiency preparation of MXene. The preparation method of the MXene physical puffing stripping chemical etching comprises the following steps: (1) Placing a MAX phase precursor in a supercritical reaction kettle, introducing carbon dioxide, regulating and controlling to a set temperature and pressure to enable the carbon dioxide to reach a supercritical state for physical puffing, stirring at constant temperature and constant pressure for a certain time, and then carrying out physical puffing and pressure relief treatment, wherein the physical puffing and pressure relief operation is repeated for n times, and n is an integer greater than or equal to 2, so as to obtain a product after the physical puffing and peeling treatment; (2) Putting the physically puffed product obtained in the step (1) and a fluorine-free etchant into a supercritical reaction kettle, introducing carbon dioxide again, regulating and controlling the temperature and the pressure to maintain the carbon dioxide in a supercritical state, and simultaneously carrying out supercritical etching reaction for a preset period of time in a stirring or fluid circulation mode; (3) After the supercritical etching reaction is completed, carrying out instantaneous blasting treatment on the reaction system to realize further puffing and stripping of the product; (4) And taking out the reaction product, and washing the reaction product to be neutral to obtain the target MXene. Preferably, n in the step (1) is 2 to 6. Preferably, the MAX phase is Ti 3AlC2、Nb2AlC、Ti2AlC、Mo2GaC、Ti3 AlCN or V 2 AlC, and the corresponding MXene is Ti3C2TX、Nb2CTX、Ti2CTX、Mo2CTX、Ti3CNTX or V 2CTX, wherein T X is a surface functional group, and the surface functional group is=O or-OH. Preferably, the temperature set in the step (1) is 32-150 ℃, the pressure is 8-30 mpa, and the stirring time is 1-10 h. Preferably, the fluorine-free etching agent i