CN112194135B

CN112194135B - Method for preparing MXenes material from molten salt

Info

Publication number: CN112194135B
Application number: CN202011131252.XA
Authority: CN
Inventors: 林紫锋; 刘颖; 陈津津
Original assignee: Sichuan University
Current assignee: Sichuan University
Priority date: 2020-10-21
Filing date: 2020-10-21
Publication date: 2022-03-01
Anticipated expiration: 2040-10-21
Also published as: CN112194135A

Abstract

The invention particularly relates to a method for preparing MXenes materials from molten salts, which comprises the steps of adopting halide salts as a salt bed, heating and melting MAX phases, Lewis acid salts and the halide salts, cooling, washing off by-products by deionized water and an oxidant, and carrying out suction filtration and drying to obtain the MXenes materials. The method is carried out in air atmosphere, has short preparation time, and can obviously reduce the production cost and improve the production efficiency.

Description

Method for preparing MXenes material from molten salt

Technical Field

The invention belongs to the field of MXenes materials, and particularly relates to a method for preparing an MXenes material from molten salt.

Background

Since the emergence of MXenes materials in 2011, MXenes materials have a wide application prospect in many fields such as energy storage, catalysis, sewage purification, optics and the like, particularly in the aspect of electrochemical energy storage due to a unique two-dimensional layered structure and excellent conductivity.

The MXenes material is prepared by mainly using HF solution with high concentration or LiF and HCl with high concentration to generate HF in situ to etch MAX phase material, and the method has great harm to environment and human body because HF has strong corrosivity; in 2019, research suggests that MXenes materials are prepared by etching MAX phase by using molten Lewis acid salt and keeping the temperature of the molten Lewis acid salt at the temperature of more than 650 ℃ for more than 5 hours, and Ti is successfully prepared₃C₂Tx MXenes has good lithium storage performance, is safer and has shorter preparation time compared with the HF etching method, but the method needs argon protection, increases the cost, needs heat preservation for more than 5 hours at the temperature of more than 650 ℃, and has longer preparation time. Therefore, a method which can prepare the MXenes material without argon protection and has a short preparation period is needed to be found so as to reduce the production cost and improve the production efficiency.

Disclosure of Invention

The invention aims to provide a method for preparing MXenes materials from molten salt aiming at the defects of the existing method for preparing MXenes materials, so as to shorten the heat preservation time and reduce the production cost.

In order to achieve the above object, the present invention is realized by the following method:

a method for preparing MXenes material from molten salt comprises the steps of adopting halide salt as a salt bed, heating and melting MAX phase, Lewis acid salt and halide salt, cooling, washing off by-products by deionized water and an oxidant, carrying out suction filtration and drying to obtain the MXenes material.

Specifically, the method comprises the following steps:

(1) firstly, grinding the MAX phase, the Lewis acid salt and the halide salt for 5-10 min by using a mortar to uniformly mix, and then transferring the mixture into a crucible;

(2) grinding halide salt by using a mortar for 5-10 min to uniformly mix, and then transferring the mixture into the crucible in the step (1) and covering the mixture prepared in the step (1) to be used as a salt bed;

(3) transferring the crucible which is finished in the step (2) to a muffle furnace, preserving the heat for 20-90 min at 200-1000 ℃, and then taking out the crucible and cooling;

(4) and taking out the solidified product, dissolving the solidified product in deionized water, adding an oxidant to remove a byproduct, carrying out suction filtration, and drying the product after suction filtration to obtain the MXenes material.

Or, the method specifically comprises the following steps:

(1) firstly, grinding the Lewis acid salt and the halide salt by using a mortar for 5-10 min to uniformly mix, and then transferring the mixture into a crucible;

(3) transferring the crucible which is finished in the step (2) to a muffle furnace, preserving heat at 200-1000 ℃, adding 0.5-1 g of MAX phase after the halide salt is melted, preserving heat for 20-90 min, taking out the crucible and cooling;

Wherein the Lewis acid salt is CuCl₂、ZnCl₂、FeCl₂、NiCl₂、CuBr₂One kind of (1).

The molar ratio of the MAX phase to the Lewis acid salt is 1: 3-1: 6.

wherein the halide salt is CaCl₂、NaCl、KCl、MgCl₂At least one of (1).

The oxidant is ammonium persulfate APS and FeCl₃One kind of (1).

Preferably, the cooling method is at least one of air cooling, furnace cooling and air cooling.

The drying method is one of vacuum oven drying, freeze drying and natural drying.

Compared with the prior art, the invention has the following beneficial effects:

1. the method is carried out in the atmosphere, so that the protection of argon is not needed, and the production cost can be effectively reduced;

2. the MXenes material can be obtained only by heat preservation for 20-90 min, and compared with a method for preserving heat for 5-24 h, the method has the advantages that the reaction time is greatly shortened, and the MXenes material preparation efficiency is improved.

Drawings

FIG. 1 shows Ti prepared in example 1₃C₂XRD pattern of Tx MXenes material.

FIG. 2 shows Ti prepared in example 2₃C₂XRD pattern of Tx MXenes material.

FIG. 3 shows Ti prepared in example 1₃C₂SEM morphology of Tx MXenes material.

FIG. 4 shows Ti prepared in example 2₃C₂SEM morphology of Tx MXenes material.

Detailed Description

The invention is further illustrated by the following examples.

Example 1

The method for preparing the MXenes material by using the molten salt comprises the following steps:

(1) firstly, Ti₃AlC₂And CuCl₂With KCl and NaCl at 1: 4: 3: 3 for 5min in a mortar to uniformly mix the powders, wherein Ti₃AlC₂0.5g, and then transferred to a crucible;

(2) NaCl and KCl were mixed at a ratio of 1: 1, wherein the NaCl is 0.1 mol, is ground by a mortar for 5min to uniformly mix, and then transferred into the crucible of the step (1) and covered on the mixture prepared in the step (1) to be used as a salt bed;

(3) transferring the crucible which is finished in the step (2) to a muffle furnace, heating to 660 ℃ at the speed of 8 ℃/min, preserving heat at 660 ℃ for 30min, stopping the heating process after the heat preservation is finished, and cooling the crucible along with the furnace;

(4) taking out the solidified product, dissolving the solidified product in deionized water, adding Ammonium Persulfate (APS) to remove Cu, performing suction filtration, placing the product after suction filtration in a culture dish, and performing freeze drying on the product in a freeze dryer for one night to obtain Ti₃C₂Tx MXenes material.

Ti prepared in example 1₃C₂The XRD pattern and SEM appearance of the Tx MXenes material are shown in figure 1 and figure 3 respectively.

Example 2

(1) firstly, CuCl is added₂With CaCl₂And NaCl as a 4: 3: 3 for 5min in a mortar to mix the powders uniformly, wherein the CuCl₂1.382g, then transferred to a crucible;

(2) adding CaCl₂With NaCl in a ratio of 1: 1, grinding for 5min with a mortar to mix well, wherein CaCl₂0.1 mol, then transferred to the crucible of step (1) and covered on the mixture prepared in step (1) as a salt bed;

(3) transferring the crucible which is finished in the step (2) to a muffle furnace, heating to 660 ℃ at 8 ℃/min, and preserving heat until CaCl is obtained₂Melting the mixed salt with NaCl, adding 0.5g Ti₃AlC₂Then preserving heat for 20min, stopping the heating program after the heat preservation is finished, and taking out the crucible for air cooling;

Ti prepared in example 2₃C₂The XRD pattern and SEM morphology of the Tx MXenes material are shown in figure 2 and figure 4 respectively.

Claims

1. a method for preparing MXenes material by molten salt, it is characterized in that, adopt halide salt as salt bed, MAX phase, Lewis acid salt and halide salt are heated and melted, and by-product is washed away with deionized water and oxidant after cooling , and then the MXenes material was obtained by suction filtration and drying;

Include the following steps:

(1) First, grind the MAX phase, Lewis acid salt and halide salt with a mortar for 5-10 minutes to mix them uniformly, and then transfer them to a crucible;

(2) grinding the halide salt with a mortar for 5-10 minutes to make the mixing uniform, then transferring it to the crucible in step (1) and covering it on the mixture prepared in step (1) as a salt bed;

(3) transfer the crucible that has been batched in step (2) into a muffle furnace and keep the temperature at 200～1000°C for 20～30min, then take out the crucible and cool;

(4) taking out the solidified product and dissolving it in deionized water, then adding an oxidant to remove by-products and then suction filtration, and drying the suction-filtered product to obtain MXenes material;

Alternatively, include the following steps:

(1) First, the Lewis acid salt and the halide salt are ground with a mortar for 5-10 minutes to make the mixing uniform, and then transferred to the crucible;

(3) transfer the crucible that has been batched in step (2) into a muffle furnace and keep it at 200～1000 ℃, add 0.5g～1g MAX phase after the halide salt is melted and keep it for 20min, then take out the crucible and cool it;

Above-mentioned steps are all carried out under atmospheric atmosphere, do not need argon protection;

The Lewis acid salt is one of CuCl ₂ , ZnCl ₂ , FeCl ₂ , NiCl ₂ , and CuBr ₂ ;

The halide salt is at least one of CaCl ₂ , NaCl, KCl and MgCl ₂ .

2 . The method for preparing MXenes material from molten salt according to claim 1 , wherein the molar ratio of the MAX phase to the Lewis acid salt is 1:3 to 1:6. 3 .

3 . The method for preparing MXenes material from molten salt according to claim 1 , wherein the oxidant is one of ammonium persulfate APS and FeCl ₃ . 4 .

4 . The method for preparing MXenes material from molten salt according to claim 1 , wherein the cooling method is at least one of air cooling, furnace cooling and air cooling. 5 .

5. The method for preparing MXenes material from a molten salt according to claim 1, wherein the drying method is one of vacuum oven drying, freeze drying and natural drying.