A layered composite material and a preparation method thereof

Abstract

The present invention discloses a layered composite material and a preparation method thereof, belonging to the technical field of composite materials. In the present invention, layered double metal hydroxides are grown on the surface of MXene, and a pretreatment step of low-temperature heat treatment is introduced in its preparation method, so that a layered composite material with a 3D flower-like structure can be prepared at a relatively low temperature. The mass fraction of MXene is 5%-70%, and the layered double metal hydroxides adhere to the surface of MXene and form a 3D flower-like structure. In addition, by adjusting the preparation process and processing temperature, the microscopic morphology of the layered composite material can be accurately regulated, and its specific surface area can be precisely controlled synchronously. The regulation of this structure is very important for its applications in the fields of separation and adsorption, catalysis and catalyst carriers, biosensing, photochemistry, electromagnetic shielding, battery energy, aerospace, military defense, ships and vessels, and information communication.

Description

Technical Field

[0001] The present invention relates to a layered composite material and a preparation method thereof, belonging to the technical field of composite materials. Background Art

[0002] In recent years, with the research progress of functional composite materials, the requirements for functional materials in the fields of separation and adsorption, catalytic carriers, electromagnetic shielding, etc. have gradually increased, which mainly focus on the morphological structure and specific surface area of composite materials. According to research findings, composite materials with regular micro-morphologies are helpful for more convenient control during application, so as to fully exert their special functions. A higher specific surface area can provide more active sites for catalyst attachment or separation and adsorption, etc., thereby improving their use efficiency. At present, in order to prepare composite materials with a high specific surface area and regular micro-morphologies, they are often obtained through complex synthesis processes, and these methods limit their industrial application and development. Therefore, how to prepare composite materials with controllable morphology, stable structure and large specific surface area by simple methods is the most effective way to solve their industrial application. Considering that layered double metal hydroxides are a kind of semiconductor materials, which have the advantages of rich raw materials, simple preparation methods, stable structures, etc., their ultra-high specific surface area and unconventional physical and chemical, electronic and optoelectronic properties have been proven to have positive significance in the fields of biosensing, photochemistry, electromagnetic shielding, etc. However, layered double metal hydroxides still have problems such as poor conductivity, easy corrosion and difficult regulation of micro-morphology.

[0003] In summary, it is of particular importance to develop a composite material with controllable morphological structure and high specific surface area. Summary of the Invention

[0004] In view of the above problems existing in the prior art, the present invention provides a layered composite material and a preparation method thereof.

[0005] During the preparation process of the composite material, by controlling the composition and feeding ratio of layered double metal hydroxides and MXene, and the preparation method, a layered double metal hydroxide@MXene composite material with controllable conductivity, controllable morphology and stable structure can be obtained, which is expected to form a conductive path and excellent magnetic path in the polymer matrix, thereby being beneficial to improving the electromagnetic shielding performance of the polymer / layered double metal hydroxide@MXene composite material.

[0006] The first object of the present invention is to provide a layered composite material, which is composed of layered double metal hydroxides and MXene, wherein the mass fraction of MXene is 5%-70%, the layered double metal hydroxides are attached to the surface of MXene and form a 3D flower-like structure with a particle size of 0.5 μm - 10 μm.

[0007] The second object of the present invention is to provide a method for preparing a layered composite material, comprising the following steps:

[0008] (a) Adding an MXene dispersion, a metal salt mixture, and a precipitating agent to water, and mixing evenly to obtain a mixed solution;

[0009] (b) Subjecting the mixed solution obtained in step (a) to preheating treatment to obtain a heat-treated mixture;

[0010] (c) Then subjecting the heat-treated mixture in step (b) to secondary heating treatment to obtain a product;

[0011] (d) Taking out the product obtained in step (c), washing and drying it to obtain the layered composite material.

[0012] In one embodiment of the present invention, in step (a), the MXene in the MXene dispersion is a single or few-layer structure, with a thickness of 1 nm - 12 nm and a size of 0.5 μm - 2 μm.

[0013] In one embodiment of the present invention, in step (a), the concentration of the MXene dispersion is 0.01 - 0.05 g / mL.

[0014] In one embodiment of the present invention, in step (a), the concentration of MXene in the obtained mixed solution is 0.001 g / mL - 0.01 g / mL.

[0015] In one embodiment of the present invention, in step (a), the metal salt mixture is a metal salt mixture of divalent metal M 2+ and trivalent metal M 3+ ; the M 2+ is any one of Mg 2+ , Ni 2+ , Co 2+ , Zn 2+ and Cu 2+ , and the M 3+ is any one of Al 3+ , Cr 3+ , Fe 3+ and Sc 3+ ; the molar ratio of the metal salts of divalent metal M 2+ and trivalent metal M 3+ is (1 - 4):1.

[0016] Preferably, the divalent metal M 2+ is Ni 2+ .

[0017] Preferably, the trivalent metal M 3+ is Fe3+ 。

[0018] In one embodiment of the present invention, in step (a), the concentration of the metal salt mixture in the obtained mixed solution is 0.01 g / mL - 0.2 g / mL.

[0019] In one embodiment of the present invention, in step (a), the precipitating agent includes at least one of sodium hydroxide, potassium hydroxide, urea, and ammonia water.

[0020] Preferably, the precipitating agent is urea.

[0021] In one embodiment of the present invention, in step (a), the concentration of the precipitating agent in the obtained mixed solution is 0.015 g / mL - 0.05 g / mL.

[0022] In one embodiment of the present invention, in step (b), the heating temperature of the preheating treatment is 50°C - 80°C, and the duration is 10 min - 30 min.

[0023] In one embodiment of the present invention, in step (c), the heating temperature of the secondary heating treatment is 100°C - 150°C, and the duration is 3 h - 12 h.

[0024] Preferably, in step (c), the heating temperature is 100°C - 120°C, and the duration is 10 h - 12 h.

[0025] In one embodiment of the present invention, a method for preparing a layered composite material comprises the steps of:

[0026] (a) Adding MXene dispersion, nickel chloride, iron chloride, and urea into water, and mixing evenly to obtain a mixed solution;

[0027] The concentration of the MXene dispersion is 0.01 - 0.05 g / mL;

[0028] The mass ratio of MXene to nickel chloride in the MXene dispersion is 0.32:2 - 2.5;

[0029] The mass ratio of MXene to iron chloride in the MXene dispersion is 0.32:0.5 - 1;

[0030] The mass ratio of MXene to urea in the MXene dispersion is 0.32:1 - 2;

[0031] The mass ratio of MXene to water in the MXene dispersion is 0.32:40 - 60;

[0032] (b) Adding the mixed solution obtained in step (a) into a reaction kettle, sealing it, heating it to 50 - 60°C and maintaining for 10 - 20 min;

[0033] (c) Then, the mixture heated in step (b) is heated to 100 - 120 °C for a second time and kept at a constant temperature for 10 - 12 h;

[0034] (d) Take out the mixture obtained after the second heating in step (c), wash it and then dry it to obtain a powdery composite, which is a layered composite material with a 3D flower-like spherical structure.

[0035] The present invention provides a layered composite material prepared according to the above method.

[0036] The present invention also provides the application of the above-mentioned layered composite material in the fields of separation and adsorption, catalysis and catalyst support, biosensing, photochemistry, electromagnetic shielding, battery energy, aerospace, military defense, ships and vessels, and information communication.

[0037] The beneficial effects of the present invention are as follows:

[0038] By controlling the preparation process and conditions, the present invention grows layered double metal hydroxides on the surface of MXene and assembles them to form a layered double metal hydroxide@MXene composite material with a 3D flower-like spherical structure. A low-temperature heat treatment process is introduced in the present invention, which provides a promoting effect and effective regulation on the attachment and nucleation of layered double metal hydroxides on the surface of MXene. During this process, the low-temperature condition can effectively reduce the oxidation of MXene and make the subsequent growth process of layered double metal hydroxides faster. In addition to being able to regulate the structure of the layered double metal hydroxide@MXene composite material, this preparation process can also adjust its specific surface area, and this characteristic can provide sufficient attachment points and contact surfaces for its application. The regulation of this structure is very important for its application in the fields of separation and adsorption, catalysis and catalyst support, biosensing, photochemistry, electromagnetic shielding, battery energy, aerospace, military defense, ships and vessels, and information communication. Description of the Drawings

[0039] Figure 1 SEM images of the layered composite materials obtained in Examples 1 - 4.

[0040] Figure 2 SEM images of the layered composite materials obtained in Comparative Examples 1 - 4.

[0041] Figure 3 Specific surface areas of the layered composite materials obtained in Examples 1 - 5 and Comparative Examples 1 - 4.

[0042] Figure 4 SEM images of the layered composite materials obtained in Example 5 and Comparative Examples 5 - 6. Detailed Description of the Invention

[0043] The embodiments disclosed herein are examples of the present invention and can be embodied in different forms. Therefore, the detailed disclosure including specific structural and functional details is not intended to limit the present invention, but merely serves as a basis for the claims. It should be understood that the detailed description of the present invention is not for the purpose of limitation but to cover all possible modifications, equivalents, and substitutions that fall within the scope of the present invention as defined by the appended claims. Throughout this application, the word "may" is used in a permissive sense rather than a mandatory sense. Similarly, unless otherwise stated, the words "comprise", "include", and "consist of" mean "include but not limited to". The word "a" or "an" means "at least one", and the word "plurality" means more than one. When using abbreviations or technical terms, these terms represent the generally accepted meanings known in the relevant technical field.

[0044] Raw material source

[0045] The MXene dispersion used in the examples and comparative examples was obtained by etching and exfoliating Ti2AlC powder, and the preparation process is as follows:

[0046] (a) Add Ti2AlC powder to the etching solution and stir slowly;

[0047] (b) Heat the mixture obtained in step (a) to 30 - 60 °C and continue stirring;

[0048] (c) Then, the mixture obtained in step (b) is separated and washed multiple times to obtain the used MXene dispersion.

[0049] Among them, in step (a), the mass ratio of Ti2AlC powder to the etching solution is 1:30 - 60; the etching solution is a mixture of LiF and hydrochloric acid, where the mass fraction of LiF is 4 - 8%, and the concentration of hydrochloric acid is 5 - 9 mol / L; the stirring duration in step (b) is 12 - 24 h; the Ti2AlC powder was purchased from Foshan Newene Technology Co., Ltd. and has a size of 400 mesh.

[0050] The nickel chloride, iron chloride, and urea used in the examples and comparative examples were purchased from Sinopharm Chemical Reagent Co., Ltd.

[0051] Example 1

[0052] (a) Add 20 mL of MXene dispersion with a concentration of 0.016 g / mL, 2.14 g of nickel chloride, 0.81 g of iron chloride, and 1.8 g of urea to 50 mL of water, and mix well to obtain a mixed solution;

[0053] (b) Add the mixed solution obtained in step (a) to a reaction kettle, seal it, heat it to 50 °C and maintain it for 10 min;

[0054] (c) Reheat the reaction kettle to 100 °C for the second time and keep it at a constant temperature for 3 h;

[0055] (d) Take out the mixture obtained from the reaction in step (c), wash it multiple times and then freeze-dry it to obtain a powdery composite, which is the layered composite material.

[0056] Example 2

[0057] (a) Add 20 mL of an MXene dispersion with a concentration of 0.016 g / mL, 2.14 g of nickel chloride, 0.81 g of iron chloride and 1.8 g of urea to 50 mL of water, and mix well to obtain a mixed solution;

[0058] (b) Add the mixed solution obtained in step (a) to the reaction kettle, seal it, and heat it to 50 °C and keep it for 10 min;

[0059] (c) Reheat the reaction kettle to 100 °C for the second time and keep it at a constant temperature for 9 h;

[0060] (d) Take out the mixture obtained from the reaction in step (c), wash it multiple times and then freeze-dry it to obtain a powdery composite, which is the layered composite material.

[0061] Example 3

[0062] (a) Add 20 mL of an MXene dispersion with a concentration of 0.016 g / mL, 2.14 g of nickel chloride, 0.81 g of iron chloride and 1.8 g of urea to 50 mL of water, and mix well to obtain a mixed solution;

[0063] (b) Add the mixed solution obtained in step (a) to the reaction kettle, seal it, and heat it to 50 °C and keep it for 10 min;

[0064] (c) Reheat the reaction kettle to 100 °C for the second time and keep it at a constant temperature for 12 h;

[0065] (d) Take out the mixture obtained from the reaction in step (c), wash it multiple times and then freeze-dry it to obtain a powdery composite, which is the layered composite material.

[0066] Example 4

[0067] Compared with Example 1, in step (c), the second heating is to 150 °C, and the others are the same.

[0068] Comparative Example 1

[0069] Compared with Example 1, in step (a), the concentration of the MXene dispersion is 0 g / mL, and the others are the same.

[0070] Comparative Example 2

[0071] Compared with Example 1, step (b) is not carried out, and the others are the same.

[0072] Comparative Example 3

[0073] Compared with Example 1, in step (c), the temperature was raised to 100 °C for the second time and kept constant for 2 h, and the others were the same.

[0074] Comparative Example 4

[0075] Compared with Example 1, in step (c), the temperature was raised to 100 °C for the second time and kept constant for 14 h, and the others were the same.

[0076] SEM characterization was performed on the microtopography of the layered composites in Examples 1-4 and Comparative Examples 1-4, and the results are as Figure 1 and Figure 2 shown. In order to study the relationship between the morphology and specific surface area of the layered composites, by testing their N2 adsorption / desorption isotherms, the results are as Figure 3 shown.

[0077] According to Figure 1 and Figure 2 it can be seen that the layered composites obtained in Examples 1-3 have a unique flower-like structure. Compared with the 2D layered structure shown by the layered composite in Comparative Example 1, this flower-like structure is closely related to the composite involving MXene. Moreover, the SEM image of the layered composite in Comparative Example 2 ( Figure 2 ) shows a typical irregular sheet stacking structure, because low-temperature pretreatment (step (b)) was not carried out during the reaction process, and this low-temperature treatment process is very important for the nucleation and growth of layered FeNi hydroxide on the surface of MXene. However, in Comparative Example 2, the reactant mixture directly underwent a high-temperature growth process, which made MXene prone to oxidation and agglomeration, thus reducing the nucleation sites of FeNi hydroxide. The formation of the flower-like structure shown by the composites in Examples 1-3 is also directly related to the heat treatment during their preparation process. Compared with the incomplete petal-like structure of the composite in Comparative Example 3 ( Figure 2 ), the burr-like petal structure of the composites in Examples 1-3 is more beneficial to the formation of a higher specific surface area, which is very crucial for the application of layered composites in the biological, chemical, and food fields. Moreover, it can be found from Example 4 that reducing the growth time of the spherical structure will lead to a reduction in the spiky petals on the surface of the flower-like structure, but does not affect the overall structural characteristics. Moreover, compared with Examples 1-3, by extending the reaction time in the high-temperature stage, Comparative Example 4 shows a different morphological structure ( Figure 2 ), in which a large number of irregular stacked morphologies appear, which is caused by the collapse of the MXene framework after the consumption of FeNi at the later stage of the 14 h high-temperature reaction stage.

[0078] To specifically study the relationship between the structure of the layered composite material and its specific surface area, the N2 adsorption / desorption isotherms of each composite material were measured and its specific surface area was calculated. The results are as Figure 3 shown. Obviously, the specific surface areas of the layered composite materials in Examples 1-4 were 89.4, 96.6, 125.1, and 56.6 m 2 / g respectively, showing a pattern of increasing with the extension of the heating time, which is consistent with the previous analysis. Moreover, when MXene was not added (Comparative Example 1) and the low-temperature preheating treatment was not carried out (Comparative Example 2), the specific surface area of the layered composite material decreased suddenly, which was caused by the agglomeration of layered FeNi hydroxide and MXene. The larger specific surface area in the examples is beneficial for the material to adsorb more particles and can provide more favorable effects during its application.

[0079] Based on the above analysis, it is proved the successful composite of layered FeNi hydroxide and MXene and its influence on the morphology of the composite filler, and also proved the important role of the low-temperature preheating process during the preparation process for stabilizing the morphology. Moreover, this morphology regulation also directly affects the specific surface area of the layered composite material, and this optimization is of great significance for its application in fields such as separation adsorption, catalysis and catalyst carriers, and biosensing.

[0080] Example 5

[0081] Compared with Example 1, in step (b), the heating temperature was 80 °C and maintained for 10 min, and the others were the same.

[0082] Comparative Example 5

[0083] Compared with Example 1, in step (b), the heating temperature was 80 °C and maintained for 5 min, and the others were the same.

[0084] Comparative Example 6

[0085] Compared with Example 1, in step (b), the heating temperature was 80 °C and maintained for 40 min, and the others were the same.

[0086] The SEM images of the layered composite materials prepared in Example 5 and Comparative Examples 5-6 are as Figure 4As shown. For Example 5, the obtained layered composite material still has a flower-like spherical structure. However, due to the relatively long low-temperature heat treatment time (compared with Example 1), the spherical structure shows slightly agglomerated, and the sphere diameter is also relatively lower. This is because the higher nucleation temperature makes the layered FeNi hydroxide form more crystallization points, thus increasing its quantity and making it more dense. However, there are obvious differences in the structures of the layered composite materials in Comparative Example 5 and Comparative Example 6. The morphological structure of the layered composite material in Comparative Example 5 is similar to that in Comparative Example 1, also showing a regular lamellar structure. This is because the short low-temperature heat treatment time makes the layered FeNi hydroxide not fully adhere to the MXene surface, resulting in differences in the subsequent growth process. In Comparative Example 6, there is an obvious caking phenomenon in the flower-like spherical structure of the layered composite material, which is caused by the too long low-temperature treatment process, resulting in severe agglomeration of the layered FeNi hydroxide and MXene. Moreover, the long heat treatment process will also cause the oxidation of MXene, which is also one of the reasons for the caking phenomenon in Comparative Example 6.

[0087] Therefore, it can be seen that the low-temperature heat treatment process in step (b) of Example 1 is very important for the formation of the flower-like spherical morphology of the layered composite material. The regulation of temperature and time in this step can effectively promote the formation process of its regular structure.

[0088] Table 1 Specific surface areas of the obtained layered composite materials in Examples 1-5 and Comparative Examples 1-4

[0089] Example 1 Example 2 Example 3 Example 4 Example 5 <![CDATA[Specific surface area (m 2 / g)]]> 89.4 96.6 125.1 56.6 71.6 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 <![CDATA[Specific surface area (m 2 / g)]]> 9.6 13.8 23.6 31.8

[0090] Example 6

[0091] A layered ScMg hydroxide@MXene composite material with a 3D spherical structure.

[0092] Compared with Example 1, nickel chloride and iron chloride in step (a) are replaced by cesium chloride and magnesium chloride, and others are the same.

[0093] Example 7

[0094] A layered AlCo hydroxide@MXene composite material with a 3D spherical structure.

[0095] Compared with Example 1, nickel chloride and iron chloride in step (a) are replaced by aluminum chloride and cobalt chloride, and others are the same.

[0096] Example 8

[0097] A layered CrZn hydroxide@MXene composite material with a 3D spherical structure.

[0098] Compared with Example 1, chromium chloride and zinc chloride in step (a) are replaced with aluminum chloride and cobalt chloride, and others are the same.

[0099] Those skilled in the art should understand that the above description is only specific embodiments of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a layered composite material, characterized in that: The following steps are involved: (a) adding a MXene dispersion, a metal salt mixture and a precipitant into water and mixing them to obtain a mixed solution; the MXene in the MXene dispersion is a single few-layer structure; the metal salt mixture is a divalent metal M 2+ and trivalent metal M 3+ A mixture of metal salts; the M 2+ Mg 2+ 、Ni 2+ 、Co 2+ 、Zn 2+ and Cu 2+ Any one of the M 3+ For Al 3+ Cr 3 + , Fe 3+ and Sc 3+ Any one of: divalent metal M 2+ and trivalent metal M 3+ The molar ratio of the metal salt is 1-4:1; (b) preheating the mixed solution obtained in step (a) to obtain a heat-treated mixture; the preheating temperature is 50° C. to 80° C., and the duration is 10 min to 30 min; (c) then subjecting the mixture after the heat treatment in step (b) to a secondary heating treatment to obtain a product; the heating temperature of the secondary heating treatment is 100° C.-150° C., and the duration is 3 h-12 h; (d) taking out the product obtained in step (c), washing and drying it to obtain a layered composite material.

2. The method according to claim 1, characterized in that In step (a), the thickness of MXene in the MXene dispersion is 1 nm-12 nm, and the size is 0.5 μm-2 μm; the concentration of MXene dispersion is 0.01-0.05 g / mL; and the concentration of MXene in the obtained mixed solution is 0.001 g / mL-0.01 g / mL.

3. The method according to claim 1, characterized in that In step (a), the concentration of the metal salt mixture in the obtained mixed solution is 0.01 g / mL-0.2 g / mL.

4. The method according to claim 1, characterized in that: In step (a), the precipitant comprises at least one of sodium hydroxide, potassium hydroxide, urea and ammonia water.

5. The method according to claim 1, characterized in that In step (a), the concentration of the precipitant in the obtained mixed solution is 0.015 g / mL-0.05 g / mL.

6. The method according to claim 1, characterized in that In step (a), the divalent metal M 2+ For you 2+ .

7. The method according to claim 1, characterized in that In step (a), the trivalent metal M 3+ Fe 3+ .

8. The method according to claim 4, characterized in that In step (a), the precipitant is urea.

9. The method according to claim 1, characterized in that: In step (c), the heating temperature is 100° C.-120° C., and the heating time is 10 h-12 h.

Images