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CN-121974353-A - Method for preparing fluorine-free MXene based on supercritical fluid puffing-stripping circulation process

CN121974353ACN 121974353 ACN121974353 ACN 121974353ACN-121974353-A

Abstract

The invention discloses a method for preparing fluorine-free MXene based on a supercritical fluid puffing-stripping circulation process, and belongs to the technical field of preparation of two-dimensional nano materials. The method comprises the steps of S1, placing a fluorine-free etchant, an auxiliary agent and MAX phase in a reaction kettle, S2, introducing supercritical carbon dioxide, carrying out supercritical etching reaction through stirring, S3, carrying out instantaneous supercritical puffing stripping treatment after the reaction is finished, S4, collecting products and placing the products in the reaction kettle, repeating the steps S2 and S3 for n times, wherein n is more than or equal to 2, and S5, and taking out MXene products. The invention solves the environmental pollution problem caused by the traditional fluorine-containing reagent by utilizing the supercritical carbon dioxide and the fluorine-free etchant, combines the mechanical action of multiple supercritical puffing and stripping, improves the effect or efficiency 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. The method for preparing fluorine-free MXene based on the supercritical fluid puffing-stripping circulation process is characterized by comprising the following steps: S1, placing a fluorine-free etching agent, an auxiliary agent and MAX phase in a reaction kettle; S2, introducing supercritical carbon dioxide, and carrying out supercritical etching reaction by stirring; s3, after the reaction is finished, performing instantaneous supercritical puffing and stripping treatment; s4, collecting a product and placing the product into a reaction kettle, and repeating the steps S2 and S3 for n times, wherein n is more than or equal to 2; S5, taking out the MXene product.
  2. 2. The method of preparing fluorine-free MXene based on the supercritical fluid puffing-peeling cycle process according to claim 1, characterized in that the fluorine-free etchant is selected from one or several of sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonium hydroxide, barium hydroxide, magnesium hydroxide, ammonium hydroxide, sodium carbonate, potassium carbonate, tetramethylammonium hydroxide, tetrabutylammonium hydroxide, tetraethylammonium hydroxide, methylamine, ethylamine, dimethylamine, triethylamine, ethylenediamine, hexamethylenediamine.
  3. 3. The method for preparing fluorine-free MXene based on the supercritical fluid puffing-peeling cycle process according to claim 1, characterized in that the fluorine-free etchant is one or several selected from the group consisting of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, perchloric acid, carbonic acid, oxalic acid, formic acid, acetic acid.
  4. 4. The method for preparing fluorine-free MXene based on the supercritical fluid expansion-stripping cycle process according to claim 1, characterized in that the auxiliary agent is selected from one or several of water, ethanol, methanol, isopropanol, hydrogen peroxide, dimethyl sulfoxide and acetone.
  5. 5. The method of preparing fluorine-free MXene based on the supercritical fluid expansion-stripping cycle process according to claim 1, characterized in that the MAX phase is Ti 3 AlC 2 、Nb 2 AlC、Ti 2 AlC、Mo 2 GaC、Ti 3 AlCN or V 2 AlC.
  6. 6. The method for preparing fluorine-free MXene based on the supercritical fluid puffing-stripping cycle process according to claim 1, wherein the mass ratio of the fluorine-free etchant to MAX phase is (10-50): 1.
  7. 7. The method for preparing fluorine-free MXene based on the supercritical fluid puffing-stripping cycle process according to claim 1, wherein the stirring speed in the step S2 is 400-10000 rpm.
  8. 8. The method for preparing fluorine-free MXene based on the supercritical fluid puffing-stripping cycle process according to claim 1, wherein the temperature of the supercritical etching reaction in the step S2 is 32-250 ℃, the pressure is 7.4-30 Mpa, and the time is 1-48 h.
  9. 9. The method for preparing fluorine-free MXene based on supercritical fluid puffing-stripping cycle process according to claim 1, wherein the temperature of the instantaneous supercritical puffing stripping treatment in the step S3 is 32-250 ℃ and the pressure is 7.4-30 Mpa.
  10. 10. The method for preparing fluorine-free MXene based on the supercritical fluid puffing-stripping cycle process according to claim 1, wherein n in S4 is an integer of 2-6.

Description

Method for preparing fluorine-free MXene based on supercritical fluid puffing-stripping circulation process Technical Field The invention belongs to the technical field of two-dimensional nano material preparation, and particularly relates to a method for preparing fluorine-free MXene based on a supercritical fluid puffing-stripping circulation process. Background MXene is used as an emerging two-dimensional material, and has great application potential in the fields of energy storage, sensors, electromagnetic shielding and the like due to the unique layered structure and excellent electrical, mechanical and chemical properties, and is widely focused by scientific research and industry. Currently, MXene is mainly prepared by a liquid phase etching method, wherein a fluorine-containing etchant (such as a mixed solution of hydrofluoric acid, lithium fluoride and hydrochloric acid) is most commonly used. Fluorine-containing etchants are highly corrosive and toxic. The discharge of the fluorine-containing waste liquid can cause serious pollution to the ecological environment such as soil, water body and the like, destroy ecological balance and influence biological diversity. The fluorine ions contained in the fluorine-containing material are difficult to degrade naturally, can accumulate in the environment for a long time, and further exacerbate environmental hazard. Moreover, the fluorine-containing etchant constitutes a serious threat to the health of operators during operation, and once contacting the skin, eyes or inhaling the volatilized gases, serious consequences such as burns, poisoning and the like may be caused, and strict safety protection measures and professional operators are required to be equipped, which undoubtedly increases the safety risk and labor cost during production. Therefore, it is particularly urgent and necessary to develop a technology for preparing MXene without using fluorine-containing etchant. The technology for preparing the MXene by using the fluorine-free etchant can overcome the defects of the traditional preparation method of the fluorine-containing etchant in the aspects of efficiency, environment, safety and the like, can expand the application range of the MXene, lays a solid foundation for large-scale application of the MXene in more fields, and has great scientific significance and wide application prospect. Disclosure of Invention Aiming at the technical problems, the invention provides a method for preparing fluorine-free MXene based on a supercritical fluid puffing-stripping circulation process, which solves the environmental pollution problem caused by the traditional fluorine-containing reagent by utilizing supercritical carbon dioxide to cooperate with a fluorine-free etchant, combines the mechanical action of multiple supercritical puffing stripping, improves the effect or efficiency of chemical etching action, shortens the chemical reaction time and reduces the dosage of chemicals. The technical scheme is that the method for preparing fluorine-free MXene based on the supercritical fluid puffing-stripping circulation process comprises the following steps: S1, placing a fluorine-free etching agent, an auxiliary agent and MAX phase in a reaction kettle; S2, introducing supercritical carbon dioxide, and carrying out supercritical etching reaction by stirring; s3, after the reaction is finished, performing instantaneous supercritical puffing and stripping treatment; s4, collecting a product and placing the product into a reaction kettle, and repeating the steps S2 and S3 for n times, wherein n is more than or equal to 2; S5, taking out the MXene product. Preferably, the fluorine-free etchant is selected from one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonium hydroxide, barium hydroxide, magnesium hydroxide, ammonium hydroxide, sodium carbonate, potassium carbonate, tetramethylammonium hydroxide, tetrabutylammonium hydroxide, tetraethylammonium hydroxide, methylamine, ethylamine, dimethylamine, triethylamine, ethylenediamine, and hexamethylenediamine. Preferably, the fluorine-free etchant is one or more selected from hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, perchloric acid, carbonic acid, oxalic acid, formic acid and acetic acid. Preferably, the auxiliary agent is selected from one or more of water, ethanol, methanol, isopropanol, hydrogen peroxide, dimethyl sulfoxide and acetone. Preferably, the MAX phase is Ti 3AlC2、Nb2AlC、Ti2AlC、Mo2GaC、Ti3 AlCN or V 2 AlC. Preferably, the mass ratio of the fluorine-free etchant to the MAX phase is (10-50): 1. Preferably, the stirring speed in the step S2 is 400-10000 rpm. Preferably, the temperature of the supercritical etching reaction in the step S2 is 32-250 ℃, the pressure is 7.4-30 Mpa, and the time is 1-48 h. Preferably, the temperature of the instantaneous supercritical puffing and stripping treatment in the step S3 is 32-250 ℃ and the pressure is 7.4-30 Mpa. Preferably,