阅读说明：本技术 MXene二维材料、Cu/MXene催化剂及其制备方法与应用 (MXene two-dimensional material, Cu/MXene catalyst, and preparation method and application thereof ) 是由 张昉 张庆萧 蒋花婷 王凯旋 于 2019-11-27 设计创作，主要内容包括：本发明公开了一种MXene二维材料、Cu/MXene催化剂及其制备方法与应用。所述MXene二维材料的制备方法包括：使包含氟化锂、酸和Mxene前驱体的均匀混合反应体系反应,并采用机械震荡技术对反应产物与水的混合物震荡,再超声处理,获得MXene二维材料。本发明还公开了Cu/MXene催化剂的制备方法包括：使铜源与MXene二维材料溶液混合反应,之后离心处理,并对离心所获固形物进行干燥处理,获得Cu/MXene催化剂。本发明Cu/MXene催化剂的二维催化剂材料具有高分散性、精准控制活性组分位点位置的特点,在Sonogashira偶联反应和4-NP的还原等领域具有广泛的应用前景。(The invention discloses an MXene two-dimensional material, a Cu/MXene catalyst, and a preparation method and application thereof. The preparation method of the MXene two-dimensional material comprises the following steps: reacting a uniform mixed reaction system containing lithium fluoride, acid and a Mxene precursor, oscillating a mixture of a reaction product and water by adopting a mechanical oscillation technology, and performing ultrasonic treatment to obtain the MXene two-dimensional material. The invention also discloses a preparation method of the Cu/MXene catalyst, which comprises the following steps: and (2) mixing and reacting the copper source with the MXene two-dimensional material solution, then centrifuging, and drying the solid obtained by centrifuging to obtain the Cu/MXene catalyst. The two-dimensional catalyst material of the Cu/MXene catalyst has the characteristics of high dispersibility and accurate control of the position of active component sites, and has wide application prospects in the fields of Sonogashira coupling reaction, reduction of 4-NP and the like.)

1. A preparation method of MXene two-dimensional material is characterized by comprising the following steps:

reacting a uniformly mixed reaction system containing lithium fluoride, acid and a Mxene precursor for 5-72 h at the temperature of 20-60 ℃,

and mixing the obtained reaction product with water, vibrating the obtained mixture for 10-1200 min by adopting a mechanical vibration technology, preferably for 30-60 min, and performing ultrasonic treatment for 10-300 min to obtain the MXene two-dimensional material.

2. The method of claim 1, wherein: the mass ratio of the lithium fluoride to the acid is 1: 6-1: 40; and/or the mass ratio of the Mxene precursor to the lithium fluoride is 1: 0.6-1: 2.4; and/or the power of ultrasonic treatment is 80-360W; and/or the Mxene precursor comprises Ti₃AlC₂、Ti₂AlC、V₂AlC、Mo₂AlC、Nb₂Any one or a combination of two or more of AlC; preferably, the acid comprises hydrochloric acid and/or hydrofluoric acid.

3. An MXene two-dimensional material prepared by the process of any one of claims 1-2; preferably, the MXene two-dimensional material comprises Ti₃C₂T_x、Ti₂CT_x、Mo₂CT_x、Nb₂CT_x、V₂CT_xAny one or a combination of two or more of the two-dimensional materials; preferably, the MXene two-dimensional material is a single-layer MXene two-dimensional material; preferably, the MXene two-dimensional material is 0.8-4 nm in thickness and has a multilayer organ-shaped appearance.

4. A Cu/MXene catalyst, which is characterized by comprising the MXene two-dimensional material as a carrier and Cu nanoparticles as an active component, wherein the Cu nanoparticles are uniformly distributed on the edge of the MXene two-dimensional material.

5. The Cu/MXene catalyst according to claim 4, characterized in that: the diameter of the Cu nano particle is 0.9-3.6 nm; the loading amount of the Cu nano particles on the carrier is 0.1-2 wt%.

6. A preparation method of a Cu/MXene catalyst is characterized by comprising the following steps:

providing an MXene two-dimensional material solution comprising the MXene two-dimensional material of claim 3;

according to the mass ratio of the copper source to the MXene two-dimensional material of 0.1-2: 100, mixing a copper source and an MXene two-dimensional material solution, stirring for reaction, centrifuging, and drying a solid obtained by centrifuging to obtain the Cu/MXene catalyst.

7. The production method according to claim 6, characterized by comprising: dispersing the MXene two-dimensional material in a solvent to obtain an MXene two-dimensional material solution with the concentration of 0.01-25 mg/mL;

preferably, the solvent comprises any one or a combination of more than two of water, ethanol and DMF;

and/or the copper source comprises any one or combination of more than two of copper nitrate, copper chloride, copper sulfate and copper acetate.

8. The method according to claim 6, comprising:

dripping a copper source into the MXene two-dimensional material solution, and stirring for 0.5-6 h;

carrying out centrifugal treatment on the obtained reaction system, wherein the rotating speed of the centrifugal treatment is 2000-15000 r/min;

and drying the solid obtained by centrifugation to obtain the Cu/Ti₃C₂T_xA catalyst;

and/or the drying treatment comprises any one of freeze drying treatment, vacuum drying treatment and drying treatment;

preferably, the temperature of the freeze drying treatment is-25 to-40 ℃, and the time is 6 to 72 hours.

9. A Cu/MXene catalyst prepared by the process of any of claims 6-8.

10. Use of the Cu/MXene catalyst according to any one of claims 4-5 and 9 in Sonogashira coupling reactions, 4-NP reduction reactions, gas storage, electromagnetic shielding or catalytic sterilization.

Technical Field

The invention relates to a catalyst, in particular to a high-yield single-layer MXene two-dimensional material, a Cu/MXene catalyst material, a preparation method and an application thereof, and belongs to the technical field of catalyst preparation.

Background

Due to the special structure and surface properties of the two-dimensional material, the two-dimensional material plays an important role in the fields of energy storage and conversion, catalysis, adsorption separation and the like. The two-dimensional material has the advantages of large aspect ratio, uniform thickness, uniformity and order, and is a hot topic which is created for over ten years, so the two-dimensional material has important significance in the catalysis direction and is a good heterogeneous catalyst carrier. However, the preparation of the traditional supported two-dimensional material catalyst usually needs a surfactant and a reducing agent, the post-treatment mode is complex, and a large amount of means is needed to remove surface groups brought in the supporting process. As a new two-dimensional material, MXene has a two-dimensional shape similar to that of a conventional two-dimensional material, and has a unique self-reduction property, so that the development of a self-reduction catalyst based on MXene not only has a certain theoretical significance, but also has an important use value.

Disclosure of Invention

The invention mainly aims to provide a high-yield single-layer MXene two-dimensional material and a preparation method thereof, so as to overcome the defects in the prior art.

The invention also aims to provide the MXene catalyst and a preparation method thereof.

It is also an object of the present invention to provide the use of the aforementioned MXene catalyst.

In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:

the embodiment of the invention provides a preparation method of an MXene two-dimensional material, which comprises the following steps:

reacting a uniformly mixed reaction system containing lithium fluoride, acid and a Mxene precursor for 5-72 h at the temperature of 20-60 ℃,

and mixing the obtained reaction product with water, vibrating the obtained mixture for 10-1200 min by adopting a mechanical vibration technology, and performing ultrasonic treatment for 10-300 min to obtain the MXene two-dimensional material.

The embodiment of the invention also provides the MXene two-dimensional material prepared by the method.

Further, the MXene two-dimensional material comprises Ti₃C₂T_x、Ti₂CT_x、Mo₂CT_x、Nb₂CT_x、V₂CT_xAny one or a combination of two or more of these two-dimensional materials, but not limited thereto.

The embodiment of the invention also provides a Cu/MXene catalyst, which comprises the MXene two-dimensional material serving as a carrier and Cu nanoparticles serving as an active component and loaded on the carrier, wherein the Cu nanoparticles are uniformly distributed at the edge of the MXene two-dimensional material.

The embodiment of the invention also provides a preparation method of the Cu/MXene catalyst, which comprises the following steps:

providing an MXene two-dimensional material solution containing the MXene two-dimensional material;

according to the mass ratio of the copper source to the MXene two-dimensional material of 0.1-2: 100, mixing a copper source and an MXene two-dimensional material solution, stirring for reaction, centrifuging, and drying a solid obtained by centrifuging to obtain the Cu/MXene catalyst.

The embodiment of the invention also provides the Cu/MXene catalyst prepared by the method.

The embodiment of the invention also provides application of the Cu/MXene catalyst in the fields of Sonogashira coupling reaction, 4-NP reduction reaction, gas storage, electromagnetic shielding, sterilization catalysis and the like.

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

1) ti synthesized by the invention₃C₂T_xThe MXene two-dimensional material has a typical two-dimensional shape, and the yield is as high as 60%;

2) the invention adopts a self-reduction method, selects Ti₃C₂T_xUsing MXene two-dimensional material as two-dimensional catalyst carrierThe self-reduction performance load Cu nano-particles overcome the characteristic that the conventional carrier needs a reducing agent to reduce the catalyst, and the nano-particles with uniform distribution can be obtained without using a surfactant;

3) the catalyst material prepared by adopting a self-reduction mode has simple process and short synthesis period, avoids resource waste and is expected to be produced in a large scale; the scheme adopted by the invention is simpler, the load can be realized by utilizing the intrinsic chemical characteristics of the MXene nanosheets only by mixing and stirring the ionic solvent of Cu and the solution, the scheme is simpler, and meanwhile, the method is more environment-friendly and does not need heating, and is an environment-friendly and energy-saving preparation scheme of the catalyst;

4) the invention utilizes Ti₃C₂T_xThe MXene two-dimensional material has self-reduction and uniform dispersion of Cu nanoparticles on the edge of the MXene two-dimensional material due to the self-reduction property and the unique chemical structure of the edge of the MXene two-dimensional material, and the catalyst has good catalytic activity on sonogashira coupling reaction;

5) the invention utilizes the charge distribution at the edge of the catalyst and the uniform distribution of Cu nano particles, and simultaneously has ultrahigh activity for the reduction of 4-NP, the Cu/MXene catalyst shows the highest activity which is far beyond the level reported in the literature, and even compared with a noble metal catalyst, the activity of the Cu/MXene catalyst is still the highest;

6) the two-dimensional catalyst material of the Cu/MXene catalyst has the characteristics of high dispersibility and accurate control of the position of active component sites, has simple and controllable preparation process and low price, avoids the use of a reducing agent and a surfactant, is simple and convenient to prepare, has wide application prospects in the fields of Sonogashira coupling reaction, reduction of 4-NP and the like, and is expected to be widely applied in the aspects of gas storage, electromagnetic shielding, sterilization, catalysis and the like.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIGS. 1a and 1b are Cu/Ti films prepared according to an exemplary embodiment of the present invention₃C₂T_xTransmission electron microscopy of the catalyst material.

FIG. 2 is a Cu/Ti alloy prepared according to an exemplary embodiment of the present invention₃C₂T_xX-ray photoelectron spectroscopy (XPS) plots of the catalyst material.

FIG. 3 is a Cu/Ti alloy prepared in accordance with an exemplary embodiment of the present invention₃C₂T_xRaman spectra of the catalyst materials.

FIG. 4 shows Cu/Ti in an exemplary embodiment of the invention₃C₂T_xReaction activity of the catalyst for catalyzing 4-NP.

FIG. 5 is a Cu/Ti alloy in accordance with an exemplary embodiment of the present invention₃C₂T_xThe reaction mechanism of the catalyst for catalyzing 4-NP is shown.

Detailed Description

In view of the deficiencies in the prior art, the inventors of the present invention have made extensive studies and extensive practices to propose the technical solution of the present invention, and further explain the technical solution, the implementation process and the principle thereof, etc.

In summary, the invention is a self-reduction strategy of two-dimensional material MXene, and Ti is selected₃C₂T_xThe MXene two-dimensional material is used as a catalyst carrier, and Ti is utilized under the condition of not using a surfactant and a reducing agent₃C₂T_xAnd Ti and other metals on the surface of the MXene two-dimensional material are used as reducing agents, the Cu nano particles are reduced in situ by one step, the accurate and high-dispersion load of the copper nano particles on the edge of the two-dimensional material is realized by changing the ion type or concentration of a copper solution and the test process conditions, and the copper nano particles are expected to be widely applied to the aspects of gas storage, electromagnetic shielding, sterilization and catalysis and the like.

One aspect of the embodiment of the present invention provides a method for preparing an MXene two-dimensional material, including:

reacting a uniformly mixed reaction system containing lithium fluoride, acid and a Mxene precursor for 5-72 h at the temperature of 20-60 ℃,

and mixing the obtained reaction product with water, vibrating the obtained mixture for 10-1200 min, preferably for 30-60 min by adopting a mechanical vibration technology, and performing ultrasonic treatment for 10-300 min to obtain the MXene two-dimensional material.

In some embodiments, the mass ratio of the lithium fluoride to the acid is from 1:6 to 1: 40.

In some embodiments, the mass ratio of the Mxene precursor to the lithium fluoride is 1:0.6 to 1: 2.4.

Further, the power of the ultrasonic treatment is 80W-360W.

Further, the Mxene precursor comprises Ti₃AlC₂、Ti₂AlC、V₂AlC、Mo₂AlC、Nb₂Any one or a combination of two or more of AlC and the like, but is not limited thereto.

Further, the acid includes hydrochloric acid, but may be other acids such as hydrofluoric acid, but is not limited thereto.

As a more specific embodiment of the present invention, the Ti₃C₂T_xThe preparation method of the two-dimensional material comprises the following steps:

dissolving LiF in hydrochloric acid solution, and adding Ti₃AlC₂Reacting the powder for more than 24 hours at 37 ℃, cooling to room temperature after the reaction is finished, and then centrifugally washing by using deionized water until the pH of the supernatant is 7, wherein the method is different from a hand-shaking method and a long-time ultrasonic method in the literature, adopts a mechanical oscillation method, adds different water according to different requirements for oscillation, and obtains 60% Ti by 30min of ultrasound₃C₂T_xThe yield of the two-dimensional material is far higher than the level reported in the literature.

Another aspect of an embodiment of the invention also provides a Mxene two-dimensional material prepared by the foregoing method.

Further, the MXene two-dimensional material comprises Ti₃C₂T_x、Ti₂CT_x、Mo₂CT_x、Nb₂CT_x、V₂CT_xAny one or a combination of two or more of these two-dimensional materials, but not limited thereto.

Further, the Mxene two-dimensional material is a single-layer Mxene two-dimensional material.

Further, the Mxene two-dimensional material is 0.8-4 nm in thickness and has multilayer organ-shaped characteristics.

In conclusion, the method for stripping the MXene two-dimensional material with high yield assisted by physical oscillation, provided by the invention, has the advantages that the utilized scheme is MILD, the problems of heating and oxidation caused by long-time ultrasonic-assisted stripping are avoided, the complicated step of a hand-cranking Method (MILD) is avoided, the yield of the material is greatly improved, the surface of the material is neat and ordered, the thickness is uniform and is about 0.8-4 nm, and the MXene material with multilayer organ-shaped characteristics is obtained.

Another aspect of the embodiments of the present invention also provides a Cu/MXene catalyst, which includes an MXene two-dimensional material as a carrier, and Cu nanoparticles as an active component supported on the carrier, where the Cu nanoparticles are uniformly distributed at edges of the MXene two-dimensional material.

In some embodiments, the Cu nanoparticles have a diameter of 0.9 to 3.6nm, centered around 2.4 nm.

In some embodiments, the Cu nanoparticles are supported on the support at a loading of 0.1 to 2 wt%.

Another aspect of the embodiments of the present invention also provides a method for preparing a Cu/MXene catalyst, including:

providing an MXene two-dimensional material solution comprising the aforementioned MXene two-dimensional material;

according to the mass ratio of the copper source to the MXene two-dimensional material of 0.1-2: 100, mixing a copper source and an MXene two-dimensional material solution, stirring for reaction, centrifuging, and drying a solid obtained by centrifuging to obtain the Cu/MXene catalyst.

Further, the method preferably comprises: and (3) feeding the solution containing the copper ions and a certain mass of MXene two-dimensional material according to the specific loading capacity by controlling the feeding amount of the copper ion solution.

In some embodiments, the method of making comprises: the MXene two-dimensional material is dispersed in a solvent (such as one or a mixed solvent of water, ethanol, DMF and the like) to obtain an MXene two-dimensional material solution with the concentration of 0.01-25 mg/mL.

In some embodiments, the copper source includes any one or a combination of two or more of copper ion solutions such as copper nitrate, copper chloride, copper sulfate, and copper acetate, but is not limited thereto, by utilizing the self-reducing and edge characteristics of the material.

Further, the MXene two-dimensional material solution comprises Ti₃C₂T_x、Ti₂CT_x、Mo₂CT_x、Nb₂CT_x、V₂CT_xAnd one or more of the solutions.

In some embodiments, the method of making specifically comprises:

dripping a copper source into the MXene two-dimensional material solution, and stirring for 0.5-6 h;

carrying out centrifugal treatment on the obtained reaction system, wherein the rotating speed of the centrifugal treatment is 2000 r/min-15000 r/min;

and drying the solid obtained by centrifugation to obtain the Cu/Ti₃C₂T_xA catalyst.

Further, the drying process includes any one of a freeze-drying process, a vacuum-drying process, a baking process, and the like, but is not limited thereto.

Furthermore, the temperature of the freeze drying treatment is-25 to-40 ℃, and the time is 6 to 72 hours.

The invention utilizes MXene two-dimensional material with self-reduction property as a catalyst carrier to synthesize the supported Cu/MXene catalyst in the environment without surfactant and reducing agent, and further obtains the Cu/MXene catalyst composite material by centrifugal separation and simple freeze drying strategy.

As a more specific embodiment of the present invention, the preparation method of the active site catalyst for precisely regulating Cu/MXene comprises the following steps:

the preparation method of the Cu/MXene catalyst comprises the following steps: a mass of MXene two-dimensional material solution was diluted in an aqueous solution to a concentration of about 0.1-25 mg/mL. The solution was stirred at room temperature and Cu (NO) was added₃)₂And (3) dropwise adding the solution (or other copper sources) into the MXene two-dimensional material solution, and stirring for 0.5-6 h to observe obvious material agglomeration. The material was separated from the solvent by centrifugation at 10000 r/min. Freezing the centrifugal precipitate (namely the Cu/MXene catalyst) for 6-72 h, freezing and drying at-25-40 ℃ to obtain Cu/MXene catalyst powder, and then grinding and sieving for characterization.

Wherein the MXene two-dimensional material comprises Ti₃C₂T_x、Ti₂CT_x、Mo₂CT_x、Nb₂CT_x、V₂CT_xAny one or a combination of two or more of these two-dimensional materials, but not limited thereto.

More specifically, the Cu/Ti₃C₂T_xThe preparation method of the catalyst comprises the following steps:

A. centrifuging to neutral Ti₃C₂T_XDispersing the material in a solvent, and shaking for more than 20min at room temperature;

B. determining the concentration of the solution obtained in the step A by using a suction filtration method, and continuously storing the solution at the temperature of about 4.5 ℃;

C. diluting the solution obtained in the step B to 1mg/mL, and stirring at room temperature;

D. c, dropwise adding a copper ion solution into the solution obtained in the step C to obtain Cu/Ti₃C₂T_xThe solution of (1).

E. And D, centrifuging the solution obtained in the step D, collecting the precipitate, and freeze-drying.

Another aspect of an embodiment of the invention also provides a Cu/MXene catalyst prepared by the foregoing method.

The other aspect of the embodiment of the invention also provides application of the Cu/MXene catalyst in the fields of Sonogashira coupling reaction, 4-NP reduction reaction, gas storage, electromagnetic shielding, sterilization catalysis and the like.

In summary, according to the above technical scheme, the invention adopts a self-reduction method, selects MXene as a two-dimensional catalyst carrier, and utilizes the self-reduction performance of MXene to load Cu nanoparticles, so as to overcome the characteristic that a conventional carrier needs a reducing agent to reduce a catalyst, and obtain uniformly distributed nanoparticles without using a surfactant.

The invention utilizes the charge distribution at the edge of the catalyst and the uniform distribution of Cu nano particles, and simultaneously has ultrahigh activity for the reduction of 4-NP, the Cu/MXene catalyst shows the highest activity which is far beyond the level reported in the literature, and even compared with a noble metal catalyst, the activity of the Cu/MXene catalyst is still the highest; meanwhile, the two-dimensional catalyst material of the Cu/MXene catalyst has the characteristics of high dispersibility and accurate control of the position of active component sites, has simple and controllable preparation process and low cost, avoids the use of a reducing agent and a surfactant, is simple and convenient to prepare, has wide application prospects in the fields of Sonogashira coupling reaction, reduction of 4-NP and the like, and is expected to be widely applied in the aspects of gas storage, electromagnetic shielding, sterilization catalysis and the like.

The technical solution of the present invention is explained in further detail below with reference to several preferred embodiments and the accompanying drawings, but the present invention is not limited to the following embodiments.