Search

CN-121974352-A - MXene fluorine-free etching method based on supercritical and supercritical puffing stripping technology

CN121974352ACN 121974352 ACN121974352 ACN 121974352ACN-121974352-A

Abstract

The invention discloses an MXene fluoride-free etching method based on supercritical and supercritical puffing stripping technology, and belongs to the technical field of two-dimensional nanomaterial preparation. The method comprises the steps of S1, placing a fluorine-free etchant and MAX phase in a reaction kettle, S2, introducing supercritical carbon dioxide, performing supercritical etching reaction in a stirring or fluid circulation mode, S3, performing instantaneous supercritical puffing stripping treatment after the reaction is finished, S4, performing pressure release on a supercritical puffing stripping zone and a buffer zone thereof, collecting products, and performing centrifugation, washing and drying treatment on the products to obtain MXene. The method can effectively solve the problems of long time consumption, low efficiency, strong corrosiveness of fluorine-containing etchants, easy environmental pollution, harm to human health and safety and the like in the process of preparing the MXene by the traditional liquid phase etching method, and has the characteristics of environmental protection, ecology, environmental protection, high etching efficiency and the like.

Inventors

  • ZHANG HENGYU
  • LONG JIAJIE

Assignees

  • 苏州大学

Dates

Publication Date
20260505
Application Date
20260126

Claims (10)

  1. 1. The MXene fluoride-free etching method based on the supercritical and supercritical puffing stripping technology is characterized by comprising the following steps: s1, placing a fluorine-free etching agent and MAX phase in a reaction kettle; S2, introducing supercritical carbon dioxide, and performing supercritical etching reaction in a stirring or fluid circulation mode; s3, after the reaction is finished, performing instantaneous supercritical puffing and stripping treatment; s4, releasing pressure of the supercritical puffing stripping area and the buffer area thereof, collecting products, and centrifuging, washing and drying the products to obtain MXene.
  2. 2. The method of claim 1, wherein the fluorine-free etchant is one or more selected from the group consisting 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.
  3. 3. The method of claim 1, wherein the fluorine-free etchant is one or more selected from the group consisting of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, perchloric acid, carbonic acid, oxalic acid, formic acid, and acetic acid.
  4. 4. A supercritical sum-based system according to claim 1 an MXene fluoride-free etching method of supercritical puffing stripping technology, the method is 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.
  5. 5. The MXene fluorine-free etching method based on the supercritical and supercritical puffing peeling technology according to claim 1, wherein the mass ratio of the fluorine-free etchant to MAX phase is (10-50): 1.
  6. 6. The method for MXene fluorine-free etching based on supercritical and supercritical puffing peeling technology according to claim 1, wherein the stirring speed in the step S2 is 400-10000 rpm.
  7. 7. The method for MXene fluoride-free etching based on supercritical and supercritical puffing peeling technology 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 1-120 h.
  8. 8. The method for MXene fluorine-free etching based on supercritical and supercritical puffing peeling technology according to claim 1, wherein the temperature of the instantaneous supercritical puffing peeling treatment in the step S3 is 32-250 ℃ and the pressure is 7.4-30 Mpa.
  9. 9. The MXene fluoride-free etching method based on the supercritical and supercritical puffing peeling technology according to claim 1, wherein the rotating speed of the centrifugal treatment in the step S4 is 3500-12000 rpm, and the time is 5-20 min.
  10. 10. The method for MXene fluorine-free etching based on supercritical and supercritical puffing peeling technology according to claim 1, wherein the drying treatment time in the step S4 is 2-12 h.

Description

MXene fluorine-free etching method based on supercritical and supercritical puffing stripping technology Technical Field The invention belongs to the technical field of two-dimensional nano material preparation, and particularly relates to an MXene fluoride-free etching method based on supercritical and supercritical puffing and stripping technology. Background MXene is a novel two-dimensional transition metal carbo/nitride, has high conductivity, high specific surface area and adjustable surface chemistry, and has great potential in the fields of energy storage, electromagnetic shielding, catalysis and the like. The current industrial preparation mainly adopts hydrofluoric acid or a fluoride salt system to selectively etch the A layer in the MAX phase, and the route has the defects that (1) fluorine is inevitably introduced to the surface of an MXene sheet layer to form an inert-F end group, so that the conductivity and the electrochemical activity are reduced, (2) HF has extremely strong corrosiveness and high toxicity, serious threat to equipment, operators and environment is formed, the waste liquid treatment cost is high, (3) the reaction time is long, the subsequent ultrasonic or intercalation stripping is needed to obtain few layers of MXene, the yield is low, and (4) fluoride waste liquid is difficult to meet increasingly strict environmental regulations, so that the fluoride waste liquid becomes a core bottleneck for the large-scale application of MXene. In the prior art, some fluorine-free routes, such as electrochemical etching, an alkali thermal method, a molten salt method and the like, are explored, but the methods still have respective limitations, CN 114477181A is used for preparing MXene in a supercritical carbon dioxide system in a large scale, but the etchant is ammonium bifluoride and still generates fluorine-containing byproducts, CN 114031078B and CN116588940B are used for preparing fluorine-free MXene by adopting solid alkali to obtain molten salt, but the reaction is required to be carried out at a high temperature of more than 300 ℃, and CN 114316971B is used for preparing fluorine-free MXene quantum dots, but the 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 Aiming at the technical problems, the invention provides the MXene fluoride-free etching method based on the supercritical and supercritical puffing stripping technology, which can effectively solve the problems of long time consumption, low efficiency, strong corrosiveness of fluorine-containing etchant, easy environmental pollution, harm to human health and safety and the like in the process of preparing MXene by the traditional liquid phase etching method, and has the characteristics of environmental protection, ecology, environmental protection, high etching efficiency and the like. The technical scheme is that the MXene fluoride-free etching method based on the supercritical and supercritical puffing stripping technology comprises the following steps: s1, placing a fluorine-free etching agent and MAX phase in a reaction kettle; S2, introducing supercritical carbon dioxide, and performing supercritical etching reaction in a stirring or fluid circulation mode; s3, after the reaction is finished, performing instantaneous supercritical puffing and stripping treatment; s4, releasing pressure of the supercritical puffing stripping area and the buffer area thereof, collecting products, and centrifuging, washing and drying the products to obtain MXene. 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 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 1-120 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, the rotational speed of the centrifugal treatment in the step S4 is 3500-12000 rpm, and the time is 5-20 min. Preferably,