CN114031077A

CN114031077A - Method for rapidly preparing two-dimensional nano material MXene based on microwave irradiation

Info

Publication number: CN114031077A
Application number: CN202111291735.0A
Authority: CN
Inventors: 陶鹏; 朱静; 张竞一; 邓涛; 尚文; 宋成轶; 付本威
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Jiaotong University
Priority date: 2021-11-01
Filing date: 2021-11-01
Publication date: 2022-02-11
Anticipated expiration: 2041-11-01
Also published as: CN114031077B

Abstract

The invention relates to a method for rapidly preparing a two-dimensional nano material MXene based on microwave irradiation, which takes microwave irradiation as a heating condition, rapidly heats an etching agent, selectively etches a mother phase raw material, and is prepared by ultrasonic stripping and layering. Compared with the prior art, the preparation process based on microwave irradiation heating shortens the existing MXene preparation time from dozens of hours to dozens of minutes, and effectively solves the problems of long MXene preparation time, complex operation, high cost and the like. The traditional method needs long-time organic intercalation treatment during preparation, and in the etching process, the intercalation of water molecules and ions and the release of violent reaction gas greatly weaken the binding force between MXene layers, and the MXene with few layers and high quality can be obtained through short-time ultrasonic treatment, so that the method is suitable for large-scale preparation. The product has the same high conductivity as MXene prepared conventionally, and the photo-thermal conversion performance of near-infrared band light is greatly improved.

Description

Method for rapidly preparing two-dimensional nano material MXene based on microwave irradiation

Technical Field

The invention belongs to the technical field of nano material preparation, and relates to a method for quickly preparing a two-dimensional nano material MXene based on microwave irradiation and application thereof.

Background

Compared with zero-dimensional, one-dimensional and three-dimensional materials, the two-dimensional nano material has the characteristics of ultrathin size, large specific surface area and the like, shows a plurality of excellent performances, and is widely concerned by researchers. The traditional two-dimensional nano materials such as graphene, molybdenum sulfide, black phosphorus and the like are combined by the van der Waals force between layers, and the stripping of the sheet layer can be directly realized by ultrasonic, mechanical cutting and other modes. At present, there is a new class of MXene two-dimensional nanomaterial, in which a mother phase raw material, a MAX phase (where M represents a transition group metal such as titanium, niobium, tantalum, vanadium, etc., a represents aluminum or silicon, and X represents carbon or nitrogen), is bonded by a metal bond, and a corresponding MXene two-dimensional nanosheet material is obtained by selective etching and subsequent intercalation separation treatment. The MXene nano material has hydrophilic surface groups and metal conductivity, has a plurality of excellent properties and obtains wide attention. Meanwhile, MXene has element diversity, surface functional groups can be regulated and controlled by an etching agent and reaction conditions, and the MXene has important application potential in the fields of supercapacitors, lithium batteries, sensors, electromagnetic shielding, photothermal conversion and the like.

However, the existing MXene preparation technology still has many problems, which seriously limits the further research and practical application of MXene nano materials. With MXene (Ti) being the most commonly used one₃C₂T_x) For example, the MAX phase raw material titanium aluminum carbide (Ti)₃AlC₂) In addition, aluminum is more active than titanium and carbon and is easy to be brought into hydrofluoric acid, hydrochloric acid/lithium fluoride and the likeEtching to obtain Ti₃C₂T_xMXene. The most common preparation method at present is to heat in a water bath environment at 25-50 ℃ for slow etching, the etching process usually needs 24-48 hours to complete, and the MXene material can be obtained by subsequent long-time intercalation treatment, so the preparation process is long in time consumption and complex in operation. The traditional water bath heating temperature is not uniformly distributed in time and space, the temperature is slowly increased, if the temperature is too high, impurities are generated and oxidized, so the water bath temperature is generally set to 35-45 ℃, the preparation speed of the MXene nano material is greatly limited, only small-batch synthesis can be realized, the preparation cost is increased, and the large-scale preparation and application of MXene are seriously hindered. Therefore, there is a need to develop a simple, fast and high-quality MXene preparation method to promote further research and application of the novel two-dimensional material with excellent performance.

Disclosure of Invention

The invention aims to solve the problems of long time consumption, complex process and the like of the existing MXene nano material preparation, and provides a method for quickly preparing a two-dimensional nano material MXene based on microwave irradiation, so that the product quality is improved, the performance of the MXene in related fields is improved, and the MXene nano material can be applied.

The purpose of the invention can be realized by the following technical scheme:

the invention provides a preparation method for rapidly preparing a two-dimensional nano material MXene based on microwave irradiation, which is prepared by taking microwave irradiation as a heating condition, rapidly heating an etching agent, selectively etching a mother phase raw material and then carrying out ultrasonic stripping and layering.

Further, the parent phase raw material, i.e. MAX phase raw material (where M represents a transition group metal such as titanium, mud, tantalum, vanadium, etc., a represents aluminum or silicon, and X represents carbon or nitrogen), has elemental diversity, is generally a ceramic-like bulk material, and has a compact sandwich-like layered structure. Titanium aluminum carbide (Ti) of high purity is commonly used₃AlC₂) Wherein the aluminum is easily etched away compared to carbon and titanium, and optionally niobium aluminum carbide (Nb)₂AlC), vanadium aluminum carbide (V)₂AlC), molybdenum aluminium carbide(Mo₃AlC₂) And the like.

Further, the etchant selectively etches the a in the MAX phase, and is generally prepared from high-concentration hydrochloric acid (the concentration of the hydrochloric acid is 3-15 mol per liter) and excess lithium fluoride (the concentration of the lithium fluoride is 2-5 mol per liter), and an etchant capable of etching the a layer, such as hydrofluoric acid, high-concentration alkali and the like, can be selected.

Furthermore, the microwave irradiation power is set to be 50-300W, and the etching process can be completed after the reaction is carried out for 1-30 minutes.

Further, the preparation method based on microwave, taking titanium aluminum carbide as a mother phase raw material as an example, comprises the following steps:

(1) preparing a hydrochloric acid/lithium fluoride mixed solution with a proper concentration, uniformly stirring to obtain an etching agent, slowly adding a mother phase raw material into the etching agent, and uniformly stirring to obtain a complete reactant system;

(2) placing the reaction kettle filled with the reactants into a microwave device, setting the power to be 200W, and irradiating for 15 minutes to obtain a completely etched multilayer MXene material;

(3) and (3) centrifugally washing the completely etched multi-layer MXene product until the product is neutral, and then carrying out ultrasonic treatment to obtain the Mxene nanosheet material with few layers and even a single layer of the target product.

Under the microwave irradiation, reactants directly contact with microwaves, the microwaves are converted into heat energy through dipole rotation and ion conduction, a uniform and quick heating environment is provided, the etching process is activated, the etching reaction rate is accelerated, side reactions are inhibited, and the product purity is improved.

The reaction time is shortened, the violent gas generated in the etching process forms large thrust, the MXene interlayer acting force is effectively weakened, the interlayer distance is increased, and the etched multiple layers of MXene nano materials are subjected to ultrasonic treatment in a short time to obtain the MXene nano materials with few layers and even single layer.

The invention prepares the two-dimensional nano material MXene by a microwave irradiation method, realizes the great shortening of the preparation time by utilizing the dipole rotation and the rapid and uniform temperature rise of the ion conduction in reactants under the microwave, and simultaneously realizes the weakening of the interlayer acting force of the MXene by utilizing the intercalation of water molecules and ions and the violent gas thrust in the etching process. Therefore, the multilayer MXene material after the etching under the microwave can obtain few layers or single layers of MXene materials only through short-time ultrasonic treatment. Particularly, the microwave method can not only accelerate the reaction rate and shorten the preparation time, but also inhibit side reactions and improve the purity and quality of the product. Meanwhile, the method for preparing MXene by microwaves is simple, convenient and efficient, is easy for large-scale production, and reduces the preparation cost.

The two-dimensional nano material MXene prepared based on microwave irradiation has the characteristics of high purity and controllable size. The novel two-dimensional nano material MXene prepared based on microwave irradiation generally has few layers or a single layer and controllable size, the size of the product is 1-5 microns after one hour of ultrasonic treatment, and the size of the product is 500 nanometers after three hours of ultrasonic treatment. MXene prepared by microwave irradiation is dissolved in water to form a stable and dispersed black colloidal solution.

The invention provides an application of a two-dimensional nano material MXene prepared based on a microwave method, which has higher photo-thermal conversion performance on near-infrared band light and can be applied to the fields of biological diagnosis and treatment and the like.

Compared with the prior art, the invention has the following advantages:

(1) MXene materials are prepared by microwave irradiation, reactants directly contact with microwaves, uniform and rapid temperature rise is realized, the reaction rate is improved, and the preparation time is greatly shortened.

(2) By utilizing microwave irradiation, the reaction can be activated, unnecessary side reaction and oxidation are inhibited, and the MXene material product has high purity and high quality and has high conductivity as same as that of MXene prepared by the traditional method.

(3) The intercalation of water molecules and ions and violent gas thrust in the etching process are utilized to weaken the binding force between MXene layers, so that long-time organic matter intercalation can be avoided, and effective layering can be realized by short-time ultrasonic treatment.

(4) The convenience and high efficiency of microwave irradiation are utilized to realize the large-scale preparation of the high-quality MXene material.

(5) The MXene material prepared by microwave irradiation has excellent dispersion stability and photothermal conversion performance, and can be applied to photothermal diagnosis and treatment and other fields.

(6) The method for preparing the MXene material by microwave irradiation can be applied to different etching agents and different mother phase material systems.

Drawings

Fig. 1 is a scanning electron microscope image of a multilayer MXene nanomaterial after the product prepared in comparative example 1 (water bath heating) is subjected to ultrasound for 1 hour.

Fig. 2 is a scanning electron microscope image of a single-layer MXene nano material after the multi-layer MXene nano material prepared in example 1 (microwave) is subjected to ultrasonic treatment for 1 hour.

FIG. 3 is a scanning electron micrograph of the distribution obtained after 1 hour of ultrasonication of the product obtained in example 1 (microwave).

FIG. 4 is a statistical chart of the transverse dimension values obtained after 1 hour sonication of the product obtained in example 1 (microwave)

FIG. 5 is a scanning electron micrograph of the distribution obtained after 3 hours of ultrasonication of the product obtained in example 1 (microwave).

FIG. 6 is a statistical chart of the transverse dimension values obtained after 3 hours of sonication of the product obtained in example 1 (microwave).

Fig. 7 is a photograph of a vacuum filtered flexible film of MXene prepared in example 1 (microwave) and comparative example 1 (water bath heating).

Fig. 8 shows the conductivity of the vacuum filtered flexible films of MXene prepared in example 1 (microwave) and MXene prepared in comparative example 1 (water bath heating).

Fig. 9 shows the temperature rise of the solutions of the same concentrations of MXene prepared in example 1 (microwave) and MXene aqueous solution prepared in comparative example 1 (water bath heating) and pure water under 808nm laser irradiation.

Fig. 10 shows the extinction coefficient and the photothermal conversion efficiency of MXene prepared in example 1 (microwave) and MXene prepared in comparative example 1 (water bath heating) and water.

Fig. 11 is a photograph of a microwave mass-produced MXene colloidal solution.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.

In the following examples, unless otherwise specified, raw materials or processing techniques are all conventional materials or processing techniques in the art.

Comparative example 1

Traditional preparation of MXene

Lithium fluoride (1.6 g) was added to dilute hydrochloric acid (20 ml, 9 mol per liter) and stirred magnetically until homogeneous, then aluminum titanium carbide (1g) was added slowly and stirred magnetically until homogeneous. The reaction kettle was transferred to a bath environment at 35 ℃ and magnetically stirred in the thermostatic bath for 24 hours. The resulting solution was centrifuged several times until the pH of the solution was 6. Then dispersing the obtained precipitate into deionized water again, carrying out ultrasonic treatment on the solution for 1-3 hours, and then centrifuging the solution to obtain supernatant fluid to obtain the required Ti₃C₂T_xMXene solution of (4).

Example 1

Microwave preparation of MXene

Lithium fluoride (1.6 g) was added to dilute hydrochloric acid (20 ml, 9 mol per liter) and stirred magnetically until homogeneous, then aluminum titanium carbide (1g) was added slowly and stirred magnetically until homogeneous. And (3) transferring the reaction kettle into a microwave oven, setting the power of the microwave oven to be 200 watts, cooling for 1 minute every 4 minutes, repeating the steps for three times, and centrifuging the finally obtained solution for multiple times until the pH value of the solution is 6. Then dispersing the obtained precipitate into deionized water again, carrying out ultrasonic treatment on the solution for 1 hour and 3 hours, and then centrifuging the solution to obtain supernatant fluid to obtain the required Ti₃C₂T_xMXene solution of (4).

Example 2

Lithium fluoride (16 g) was slowly added to 200 ml of dilute hydrochloric acid (9 mol/l), magnetically stirred until homogeneous, and then titanium aluminum carbide (10 g) was slowly added, magnetically stirred until homogeneous. The reactor containing the reactants was transferred to a microwave apparatus with power set at 200 watts for every 5 minutes of irradiation, cooled for 1 minute, and irradiated for a total of 15 minutes. And centrifugally washing the etched product with deionized water until the pH value is 6, then re-dispersing the obtained precipitate in the deionized water, performing ultrasonic treatment for 1 hour, and then centrifuging the precipitate to obtain supernatant, thus obtaining a large batch of MXene colloidal solution prepared by microwave. Fig. 11 is a photograph of MXene colloidal solution prepared in bulk.

Example 3

Sodium hydroxide was dissolved in deionized water to make up 20 ml of 27.5 mol/l sodium hydroxide solution, and 0.1 g titanium aluminum carbide was slowly added to the solution. And transferring the reaction kettle filled with the reactants into a microwave device, setting the microwave power to 300 watts, cooling for 10 seconds after every 15 seconds of irradiation, and repeating the steps for 4 times to obtain a product after etching is finished. And then centrifugally washing the product until the pH value is 6, dispersing the obtained precipitate in deionized water again, setting the ultrasonic power to be 200W, ultrasonically treating for one hour, and then centrifugally taking supernatant to obtain the colloidal solution of the target product MXene.

Example 4

Lithium fluoride (1.6 g) was added to dilute hydrochloric acid (20 ml, 9 mol per liter) and stirred magnetically until homogeneous. Then slowly adding niobium aluminum carbide (Nb)₂AlC, 1g) and stirring uniformly by magnetic force, transferring the reaction kettle into a microwave oven, setting the power of the microwave oven to 50 watts, cooling for 1 minute every 5 minutes of heating, repeating for 6 times, and centrifuging the finally obtained solution for multiple times until the solution is neutral. Then dispersing the obtained precipitate into deionized water again, carrying out ultrasonic treatment on the solution for one hour, and then centrifuging the solution to obtain supernatant fluid to obtain the required Nb₂CT_xMXene colloidal solution of (ii).

Fig. 1 is a scanning electron microscope image of MXene in a multilayer state after ultrasonication prepared in comparative example 1 (water bath heating). As can be seen, short-time sonication does not achieve effective lamellar separation, and therefore further intercalation is required.

Fig. 2 is a scanning electron microscope image of a monolayer MXene after ultrasonic treatment of the two-dimensional nanomaterial MXene prepared in example 1 (microwave). FIGS. 3 to 6 are the scanning electron micrographs of the distribution of the product obtained in example 1 (microwave) after 1 hour of ultrasound and 3 hours of ultrasound, respectively, and the corresponding statistical figures of the transverse dimensions. As can be seen from the figure, after the MXene obtained by microwave etching is subjected to ultrasonic treatment for 1 hour, a micron-sized small-layer or single-layer large nanosheet layer material can be obtained, and when the ultrasonic treatment reaches 3 hours, the transverse dimension of the MXene is reduced to hundreds of nanometers. The method for preparing the microwave can effectively reduce the time of organic molecule intercalation in the traditional preparation method, can obtain few-layer or single-layer MXene nano-sheet layers only by short-time ultrasound, and can realize the controllability of the transverse dimension of the nano-sheet layers.

Conductivity determination experiment: the MXene solutions prepared in comparative example 1 (heated in a water bath) and example 1 (microwave) are subjected to vacuum filtration and dried to obtain the MXene film with metallic luster and high flexibility. Fig. 7 is a photograph of two flexible films. And respectively measuring the thicknesses of the two MXene flexible films by using a scanning electron microscope, and then measuring the response conductivity by using four probes. Fig. 8 shows the conductivity of two flexible films, wherein the conductivity of MXene prepared in comparative example 1 (heated in a water bath) is 4200S/cm, and the conductivity of MXene prepared in example 1 (microwave) is 4000S/cm.

Near-infrared laser photothermal conversion determination experiment: the obtained Mxene material is placed under a near infrared laser with set power of 808nm, and the temperature rise change in the solution is measured by a data acquisition instrument. And (3) closing the near-infrared laser after a certain time, and measuring the cooling change in the solution by using a data acquisition instrument. FIG. 9 shows the pure water collected by the data collector and MXene solution prepared in comparative example 1 (water bath heating) and MXene solution prepared in example 1 (microwave) in the same concentration (0.125mg/ml) under 808nm laser irradiation (1.5W/cm)²) Temperature change of the lower. As shown in fig. 10, the temperature of pure water was not significantly changed under laser irradiation, while the temperature of the solution of MXene was significantly increased, and MXene prepared in example 1 (microwave) was increased to a higher temperature in the same time than MXene prepared in comparative example 1 (water bath heating). This shows that compared with the MXene prepared in the proportion 1 (heating in a water bath), the MXene prepared in the example 1 (microwave) has obviously improved photo-thermal conversion performance for light in the near infrared band. FIG. 10 shows extinction coefficients and photothermal conversion of different materials, including MXene prepared in example 1 (microwave) and MXene prepared in comparative example 1 (water bath heating)The case of efficiency. MXene prepared in comparative example 1 (Water bath heating) had an extinction coefficient and a photothermal conversion coefficient of 25.2Lg, respectively^-1cm^-1And 30.6% respectively for MXene prepared in example 1 (microwave) with an extinction coefficient of 39.7Lg^- ¹cm^-1And 48.7%. The result shows that compared with MXene prepared by other two-dimensional nano materials and a traditional method, MXene prepared by microwave has more excellent photo-thermal conversion performance.

The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.

Claims

1. A method for quickly preparing high-quality two-dimensional nano material MXene based on microwave irradiation is characterized in that microwave irradiation is used as a heating condition, an etching agent is quickly heated, a mother phase raw material is selectively etched, and then ultrasonic stripping and layering are carried out to prepare the high-quality two-dimensional nano material MXene.

2. The method for rapidly preparing the high-quality two-dimensional nanomaterial MXene based on microwave irradiation of claim 1, wherein the parent phase raw material is MAX phase raw material, wherein M represents transition group metal, A represents aluminum or silicon, and X represents carbon or nitrogen.

3. The method for rapidly preparing the high-quality two-dimensional nanomaterial MXene based on microwave irradiation of claim 2, wherein the matrix raw material is titanium aluminum carbide, niobium aluminum carbide, vanadium aluminum carbide or molybdenum aluminum carbide.

4. The method for rapidly preparing the high-quality two-dimensional nanomaterial MXene based on microwave irradiation as claimed in claim 2, wherein the etchant selectively etches A in MAX phase, and is prepared from hydrochloric acid and lithium fluoride, or hydrofluoric acid and high concentration alkali.

5. The method for rapidly preparing the high-quality two-dimensional nanomaterial MXene based on microwave irradiation of claim 1, wherein the microwave irradiation power is 50-300W, and the irradiation time is 1-30 minutes.

6. The method for rapidly preparing the high-quality two-dimensional nano material MXene based on microwave irradiation as claimed in claim 1, wherein the ultrasonic delamination is achieved by separating the etched multi-layer MXene material into a few layers or even a single layer of MXene material by ultrasonic oscillation in a solution in a short time.

7. The method for rapidly preparing the high-quality two-dimensional nano material MXene based on microwave irradiation as claimed in claims 1-5, wherein titanium aluminum carbide is used as the parent phase raw material, comprising the following steps:

(2) placing the reaction kettle filled with the reactants into a microwave device, setting the microwave irradiation power to be 50-300W, and irradiating for 1-30 minutes to obtain a completely etched multilayer MXene material;

(3) centrifugally washing the completely etched multilayer MXene product to be neutral, then carrying out ultrasonic treatment,

thus obtaining the MXene nanosheet material with few layers or even a single layer of the target product.

8. The method for rapidly preparing the high-quality two-dimensional nano material MXene based on microwave irradiation as claimed in claim 1, wherein the prepared MXene has the same high conductivity as MXene prepared by traditional method.

9. The application of the two-dimensional nano material MXene prepared by the method for rapidly preparing the high-quality two-dimensional nano material MXene based on microwave irradiation according to claim 1 is characterized in that the prepared MXene material has high photothermal conversion performance in a near infrared band and can be used in the field of biological diagnosis and treatment.