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CN-121974350-A - Method for preparing MXene by fluorine-free alkali etching of ultrasonic-assisted supercritical fluid technology

CN121974350ACN 121974350 ACN121974350 ACN 121974350ACN-121974350-A

Abstract

The invention discloses a method for preparing MXene by ultrasonic assisted supercritical fluid technology fluorine-free alkali etching, which relates to the field of MXene preparation, and utilizes supercritical carbon dioxide fluid and high-frequency power ultrasonic technology to realize fluorine-free green preparation of MXene in cooperation with a fluorine-free etchant, a mixture of MAX phase material, fluorine-free etchant and auxiliary agent is placed in a supercritical reaction kettle, carbon dioxide is introduced to enable the carbon dioxide to reach a supercritical state, an etching reaction is carried out in the supercritical state in a stirring or fluid circulation mode, continuous or intermittent high-frequency power ultrasonic treatment is applied to the whole reaction system, the reaction system is restored to normal pressure and normal temperature after the reaction is finished, products are collected, washed and dried, and the removal of A layer elements in the MAX phase by using ultrasonic high-frequency vibration and high diffusivity of the supercritical carbon dioxide is promoted, so that the use of the fluorine-containing etchant is avoided, the environmental pollution is reduced, and the etching efficiency of the MAX phase is remarkably improved.

Inventors

  • ZHANG HENGYU
  • LONG JIAJIE

Assignees

  • 苏州大学

Dates

Publication Date
20260505
Application Date
20260126

Claims (10)

  1. 1.A method for preparing MXene by fluorine-free alkali etching of ultrasonic assisted supercritical fluid technology is characterized by comprising the following specific steps: the first step, uniformly mixing a fluorine-free etching agent and MAX, and then placing the mixture in a supercritical reaction kettle; Introducing carbon dioxide into the supercritical reaction kettle to enable the carbon dioxide to reach a supercritical state, and carrying out etching reaction in a stirring or fluid circulation mode; thirdly, applying continuous or intermittent high-frequency power ultrasonic treatment to the whole reaction system in the reaction process; and fourthly, after the etching reaction is finished, the whole reaction system is restored to normal pressure and normal temperature, and the product is collected.
  2. 2. The method for preparing MXene by using ultrasonic-assisted supercritical fluid technology according to claim 1, wherein the fluorine-free etchant in the first step is inorganic alkali and/or organic alkali, and the mass ratio of the fluorine-free etchant to MAX phase is that of the fluorine-free etchant: MAX phase=50:1-10:1.
  3. 3. The method for preparing MXene by using ultrasonic-assisted supercritical fluid technology according to claim 2, wherein the inorganic base is one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonium hydroxide, barium hydroxide, magnesium hydroxide, ammonium hydroxide, sodium carbonate and potassium carbonate.
  4. 4. The method for preparing MXene by using ultrasonic assisted supercritical fluid technology according to claim 2, wherein the organic base is one or more of tetramethylammonium hydroxide, tetrabutylammonium hydroxide, tetraethylammonium hydroxide, methylamine, ethylamine, dimethylamine, triethylamine, ethylenediamine and hexamethylenediamine.
  5. 5. The method for preparing MXene by ultrasonic assisted supercritical fluid etching according to claim 1, wherein the MAX phase in the first step is one or more of Ti 3 AlC 2 、Nb 2 AlC、Ti 2 AlC、Mo 2 GaC、Ti 3 AlCN、V 2 AlC.
  6. 6. The method for preparing MXene by using the ultrasonic assisted supercritical fluid technology according to claim 5, wherein the MXene corresponding to MAX is one or more of Ti 3 C 2 T X 、Nb 2 CT X 、Ti 2 CT X 、Mo 2 CT X 、Ti 3 CN T X 、V 2 CT X , and T X is a surface functional group.
  7. 7. The method of preparing MXene by ultrasonic assisted supercritical fluid etching according to claim 6, characterized in that T X is =o and/or-OH.
  8. 8. The method for preparing MXene by using the ultrasonic-assisted supercritical fluid technology according to claim 1, wherein in the second step, the temperature is controlled to be 32-250 ℃ and the pressure is controlled to be 7.4-30 Mpa, so that carbon dioxide reaches the supercritical state, and an etching reaction is carried out by adopting a stirring or fluid circulation mode, wherein the stirring rotating speed is 400-10000rpm, and the treatment time is 1-72 h.
  9. 9. The method for preparing MXene by using the ultrasonic-assisted supercritical fluid technology according to claim 1, wherein the ultrasonic power of the high-frequency power in the third step is 200-800 w, and the ultrasonic application time of the high-frequency power in the third step is 1-20h.
  10. 10. The method for preparing MXene by using the ultrasonic-assisted supercritical fluid technology according to claim 1, wherein after the product is collected in the fourth step, the product is washed and dried, the washed solvent is ethanol or deionized water which is alternately washed until the pH is more than or equal to 6, and then the product is freeze-dried for 24 hours to obtain MXene powder.

Description

Method for preparing MXene by fluorine-free alkali etching of ultrasonic-assisted supercritical fluid technology Technical Field The application relates to the technical field of MXene preparation, in particular to a method for preparing MXene by fluorine-free alkali etching by an ultrasonic-assisted supercritical fluid technology. Background The MXene material is used as an emerging two-dimensional transition metal carbide/nitrogen compound, and has huge application potential in the fields of energy storage, catalysis, sensing, biomedicine and the like due to the unique layered structure, excellent conductivity, hydrophilicity and tunable surface chemical property. However, the conventional preparation method of the MXene material mainly depends on a fluorine-containing etchant (such as hydrofluoric acid, a mixture of lithium fluoride and hydrochloric acid) to etch the A layer element in the MAX phase material, and the process has the environmental pollution risk, and fluorine functional groups are introduced into the surface of the MXene to damage the conductivity of the MXene material, so that the application of the MXene material in high-performance electronic devices is limited. Therefore, developing a green, efficient, low-cost preparation method for an MXene material is a hot spot and a difficult point of current research. Some fluorine-free routes such as electrochemical etching, an alkali thermal method, a molten salt method and the like have been explored in the prior art, but the methods still have respective limitations, patent CN 114031078B discloses a preparation method of fluorine-free MXene two-dimensional nano-sheets, CN116588940B discloses a green preparation method of fluorine-free MXene and application thereof in lithium sulfur batteries, solid alkali is adopted to obtain molten salt to prepare fluorine-free MXene, the reaction is required to be carried out at a high temperature of more than 300 ℃, and CN 114316971B discloses a preparation method of fluorine-free MXene quantum dots, but intrinsic characteristics of MXene are destroyed. Therefore, developing a low-cost and scalable fluorine-free preparation technology becomes a key requirement for promoting the green production industrialization of MXene. Disclosure of Invention The invention provides a method for preparing MXene by ultrasonic-assisted supercritical fluid technology fluorine-free alkali etching, which solves the technical problems of environmental pollution risk, damage of intrinsic characteristics of MXene, damage of conductivity, limitation of application of MXene materials in high-performance electronic devices and the like in the prior art. The invention aims to provide a method for preparing MXene by ultrasonic assisted supercritical fluid technology fluorine-free alkali etching, which comprises the steps of carrying out etching, intercalation and stripping on MXene by supercritical carbon dioxide fluid and ultrasonic oscillation, utilizing a fluorine-free etchant carried by the strong permeability of the supercritical carbon dioxide to act on the surface and interlayer of the MXene, and accelerating the reaction process under the ultrasonic oscillation to realize fluorine-free efficient preparation of the MXene. The technical scheme is that the method for preparing MXene by fluorine-free alkali etching of ultrasonic assisted supercritical fluid technology comprises the following specific steps: the first step, uniformly mixing a fluorine-free etching agent and MAX, and then placing the mixture in a supercritical reaction kettle; Introducing carbon dioxide into the supercritical reaction kettle to enable the carbon dioxide to reach a supercritical state, and carrying out etching reaction in a stirring or fluid circulation mode; thirdly, applying continuous or intermittent high-frequency power ultrasonic treatment to the whole reaction system in the reaction process; and fourthly, after the etching reaction is finished, the whole reaction system is restored to normal pressure and normal temperature, and the product is collected. Further, the fluorine-free etchant in the first step is inorganic alkali and/or organic alkali, and the mass ratio of the fluorine-free etchant to the MAX phase is that the fluorine-free etchant is MAX phase=50:1-10:1. Further, the inorganic base is one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonium hydroxide, barium hydroxide, magnesium hydroxide, ammonium hydroxide, sodium carbonate and potassium carbonate. Further, the organic base is one or more of tetramethyl ammonium hydroxide, tetrabutyl ammonium hydroxide, tetraethyl ammonium hydroxide, methylamine, ethylamine, dimethylamine, triethylamine, ethylenediamine and hexamethylenediamine. Further, the MAX phase in the first step is one or more of Ti 3AlC2、Nb2AlC、Ti2AlC、Mo2GaC、Ti3AlCN、V2 AlC. Further, the MXene corresponding to the MAX is one or several kinds of Ti3C2TX、Nb2CTX、Ti2CTX、Mo2CTX、Ti3CN TX、V2CTX, where