阅读说明：本技术 一种制备不同晶型二硫化钼的方法 (Method for preparing molybdenum disulfide with different crystal forms ) 是由 彭润玲 杜航 郭俊德 杨卓宇 肖明春 翟浩楠 曹蔚 于 2021-09-24 设计创作，主要内容包括：本发明涉及无机纳米粉体技术领域,具体涉及一种制备不同晶型纳米二硫化钼的制备方法。为克服现有技术存在的纳米二硫化钼晶型调控难和存在团聚现象的问题.本发明采用的方法步骤为:步骤1：首先制备二硫化钼前驱体溶液,将0.4-1.5g钼源和0.3-2.3g硫源加入到50ml去离子水中,搅拌得到分散均匀的透明溶液；步骤2：将上述透明溶液置于内衬为聚四氟乙烯的高压反应釜中进行反应；步骤3：停止反应后,待体系自动降温到室温,打开高压反应釜,将反应混合液倒入离心管中,离心,水洗,过滤,冷冻干燥得到产物。(The invention relates to the technical field of inorganic nano powder, in particular to a preparation method for preparing nano molybdenum disulfide with different crystal forms. In order to solve the problems of difficult regulation and control of the crystal form of the nano molybdenum disulfide and agglomeration in the prior art, the method adopted by the invention comprises the following steps of 1: firstly, preparing a molybdenum disulfide precursor solution, adding 0.4-1.5g of molybdenum source and 0.3-2.3g of sulfur source into 50ml of deionized water, and stirring to obtain a uniformly dispersed transparent solution; step 2: putting the transparent solution into a high-pressure reaction kettle with a polytetrafluoroethylene lining for reaction; and step 3: and after the reaction is stopped, automatically cooling the system to room temperature, opening the high-pressure reaction kettle, pouring the reaction mixed liquid into a centrifuge tube, centrifuging, washing with water, filtering, and freeze-drying to obtain the product.)

1. A method for preparing molybdenum disulfide with different crystal forms is characterized by comprising the following steps: the method comprises the following steps:

step 1: firstly, preparing a molybdenum disulfide precursor solution, adding 0.4-1.5g of molybdenum source and 0.3-2.3g of sulfur source into 50ml of deionized water, and stirring to obtain a uniformly dispersed transparent solution;

step 2: putting the transparent solution into a high-pressure reaction kettle with a polytetrafluoroethylene lining for reaction;

and step 3: and after the reaction is stopped, automatically cooling the system to room temperature, opening the high-pressure reaction kettle, pouring the reaction mixed liquid into a centrifuge tube, centrifuging, washing with water, filtering, and freeze-drying to obtain the product.

2. The method for preparing molybdenum disulfide in different crystal forms according to claim 1, wherein: in the step 1, the molybdenum source is sodium molybdate; the sulfur source is thiourea, and sheet and flower products can be prepared.

3. The method for preparing molybdenum disulfide in different crystal forms according to claim 1, wherein: in the step 1, the molybdenum source is ammonium molybdate; the sulfur source is thioacetamide, and a spherical product can be prepared.

4. The process for preparing molybdenum disulfide in different crystalline forms according to claim 1 or 2, characterized in that: in the step 2, the transparent solution is transferred to a 100mL closed high-pressure reaction kettle, the heating temperature is 180 ℃ and 220 ℃, and the heating time is 12-24 hours.

5. The method for preparing molybdenum disulfide in different crystal forms according to claim 4, wherein: in step 3, the centrifugal speed is 1800 rpm, and the centrifugal time is 10-20 min.

6. The method for preparing molybdenum disulfide in different crystal forms according to claim 5, wherein: in the step 3, the washing mode is as follows: washing with absolute ethyl alcohol and then washing with water for three times.

7. The method for preparing molybdenum disulfide in different crystal forms according to claim 1, wherein: and 3, before drying, freezing the precursor solution to obtain a frozen object, and then putting the frozen object into a vacuum freeze dryer, wherein the temperature of a water vapor condenser is below 50 ℃ below zero, the vacuum degree is below 30pa, and the freeze drying is finished.

8. The method for preparing molybdenum disulfide in different crystal forms according to claim 7, wherein: the freezing treatment method comprises the following steps: the molybdenum disulfide precursor solution is filled into a culture dish with the thickness of 4-6mm, and freezing is carried out at the temperature of-20 ℃ and liquid nitrogen.

Technical Field

The invention relates to the technical field of inorganic nano powder, in particular to a preparation method for preparing nano molybdenum disulfide with different crystal forms.

Background

Molybdenum disulfide is a transition metal dichalcogenide with a typical layered structure, each layer is composed of molybdenum atomic planes sandwiched between two sulfur atomic planes, has strong covalent bonds between the layers, has weak van der waals force between the molecular layers, and is easy to generate low friction under the action of shear traction force. Furthermore, a layered MoS₂The characteristics of band gap and the like are widely applied to the fields of battery cathodes, catalysts, field effect transistors and the like, such as electrocatalytic hydrogen evolution reaction, photocatalytic degradation, optical sensors and the like. The nanometer molybdenum disulfide has wide application due to unique physical and chemical properties, and the requirements of different fields on the crystal form of the molybdenum disulfide are different.

Therefore, the nano molybdenum disulfide is used as a special inorganic functional material, and the performance of the nano molybdenum disulfide is closely related to the size, the crystal form, the structure and the like. At present, the preparation method of the nano molybdenum disulfide mainly comprises a micro-mechanical stripping method, a Physical Vapor Deposition (PVD) method, a hydrothermal method, a thermal decomposition method and the like. However, the crystal form of the nano molybdenum disulfide obtained by the method is difficult to determine, and the prepared nano powder is easy to agglomerate due to intermolecular force, hydrogen bond, electrostatic action and higher surface energy among nano particles.

Disclosure of Invention

In view of the above, the invention provides a preparation method for preparing nano molybdenum disulfide with different crystal forms, in order to overcome the problems of difficult crystal form control and agglomeration of nano molybdenum disulfide in the prior art.

In order to solve the problems in the prior art, the technical scheme of the invention is as follows: a method for preparing molybdenum disulfide with different crystal forms is characterized by comprising the following steps: the method comprises the following steps:

step 1: firstly, preparing a molybdenum disulfide precursor solution, adding 0.4-1.5g of molybdenum source and 0.3-2.3g of sulfur source into 50ml of deionized water, and stirring to obtain a uniformly dispersed transparent solution;

step 2: putting the transparent solution into a high-pressure reaction kettle with a polytetrafluoroethylene lining for reaction;

and step 3: and after the reaction is stopped, automatically cooling the system to room temperature, opening the high-pressure reaction kettle, pouring the reaction mixed liquid into a centrifuge tube, centrifuging, washing with water, filtering, and freeze-drying to obtain the product.

Further, in the step 1, the molybdenum source is sodium molybdate; the sulfur source is thiourea, and sheet and flower products can be prepared.

Further, in the step 1, the molybdenum source is ammonium molybdate; the sulfur source is thioacetamide, and a spherical product can be prepared.

Further, in step 2, the transparent solution is transferred to a 100mL closed high-pressure reaction kettle, the heating temperature is 180-.

Further, in step 3, the centrifugal speed is 1800 rpm, and the centrifugal time is 10-20 min.

Further, in step 3, the washing mode is as follows: washing with absolute ethyl alcohol and then washing with water for three times.

Further, in the step 3, before drying, freezing the precursor solution to obtain a frozen object, then putting the frozen object into a vacuum freeze dryer, wherein the temperature of a water vapor condenser is below 50 ℃ below zero, the vacuum degree is below 30pa, and the frozen object can be obtained after freeze drying is finished;

further, the freezing treatment method comprises the following steps: the molybdenum disulfide precursor solution is filled into a culture dish with the thickness of 4-6mm, and freezing is carried out at the temperature of-20 ℃ and liquid nitrogen.

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

1) the invention achieves the purpose of controllable crystal forms by changing the preparation method of the precursor solution and the freezing speed of the precursor solution in the pre-freezing process, and successfully prepares the spherical, flaky and irregular flower-shaped nano molybdenum disulfide with three crystal forms.

2) The method adopts a freeze-drying method to prepare the nano molybdenum disulfide, is simple to operate, ensures the purity of the prepared product in a low-temperature vacuum environment, and is convenient to collect; in addition, the drying of the material is carried out during the freezing process, thus having a better appearance.

Drawings

FIG. 1 is an SEM electron micrograph of spherical nano-molybdenum disulfide obtained in example 1;

FIG. 2 is an SEM electron micrograph of spherical nano-molybdenum disulfide obtained in example 2;

FIG. 3 is an SEM electron micrograph of the flower-like nano disulfide obtained in example 3.

Detailed Description

The present invention will be described in further detail with reference to specific examples, but the embodiments of the present invention include, but are not limited to, the scope shown in the following examples.

Example 1

1) Weighing 1.24g of ammonium molybdate and 2.28g of thiourea at room temperature, dissolving the ammonium molybdate and the thiourea in 50ml of deionized water, and dispersing for 20min by using ultrasonic;

2) transferring the mixed solution into a 100ml high-pressure reaction kettle with a polytetrafluoroethylene lining, sealing the high-pressure kettle, and placing the high-pressure kettle in an electric heating constant-temperature drying box at the set temperature of 180 ℃ for 24 hours;

3) when the product is cooled to room temperature, placing the product on a centrifugal machine for centrifugal separation, wherein the centrifugal speed is 1800 revolutions per minute, the centrifugal time is 15 minutes, obtaining black precipitates, and respectively washing the black precipitates for multiple times by using deionized water and absolute ethyl alcohol;

4) filling the solution collected in the step 3) into a culture dish with the thickness of 4mm, directly pouring a proper amount of liquid nitrogen into the culture dish filled with the molybdenum disulfide precursor solution, completely freezing the precursor solution at a very high speed in an environment of-196 ℃, putting the precursor frozen matter into a freeze dryer for vacuum freeze drying, and obtaining the spherical nano molybdenum disulfide after freeze drying, wherein the temperature of a water vapor condenser is below-50 ℃ and the vacuum degree is below 30 pa.

Example 2

1) Weighing 0.4g of sodium molybdate and 0.6g of thioacetamide at room temperature, dissolving in 50ml of deionized water, and dispersing for 20min by using ultrasonic;

2) measuring 1.45g of surfactant polyethylene glycol, and adding the solution until the solution is completely dissolved under the condition of continuous stirring;

3) adding HCl to adjust the pH value to about 2 under the condition of continuous and violent stirring;

4) transferring the mixed solution into a 100ml high-pressure reaction kettle with a polytetrafluoroethylene lining, sealing the high-pressure kettle, and placing the high-pressure kettle in an electric heating constant-temperature drying box at the set temperature of 180 ℃ for 12 hours;

5) when the product is cooled to room temperature, placing the product on a centrifugal machine for centrifugal separation, wherein the centrifugal speed is 1800 revolutions per minute, the centrifugal time is 20 minutes, obtaining black precipitates, and respectively washing the black precipitates for multiple times by using deionized water and absolute ethyl alcohol;

6) and (3) filling the solution collected in the step (5) into a culture dish with the thickness of 5mm, directly pouring a proper amount of liquid nitrogen into the culture dish filled with the molybdenum disulfide precursor solution, completely freezing the precursor solution at a very high speed in an environment of-196 ℃, and putting the precursor frozen product into a freeze dryer for vacuum freeze drying, wherein the temperature of a water vapor condenser is below-50 ℃ and the vacuum degree is below 30 pa. And after freeze-drying, obtaining the spherical nano molybdenum disulfide.

Example 3

1) Weighing 0.48g of sodium molybdate and 0.34g of thiourea at room temperature, dissolving the sodium molybdate and the thiourea in 50ml of deionized water, and dispersing for 20min by using ultrasonic;

2) measuring a surface active agent CTAB, and adding the solution until the CTAB is completely dissolved under the condition of continuously stirring;

3) adding HCl to adjust the pH value to about 2 under the condition of continuous and violent stirring;

4) transferring the mixed solution into a 100ml high-pressure reaction kettle with a polytetrafluoroethylene lining, sealing the high-pressure kettle, and placing the high-pressure kettle in an electric heating constant-temperature drying box at the set temperature of 180 ℃ for 24 hours;

5) when the product is cooled to room temperature, placing the product on a centrifugal machine for centrifugal separation, wherein the centrifugal speed is 1800 revolutions per minute, the centrifugal time is 10 minutes, obtaining black precipitates, and respectively washing the black precipitates for multiple times by using deionized water and absolute ethyl alcohol;

6) putting the solution collected in the step 5) into a culture dish with the thickness of 6mm, freezing the solution in a refrigerator, putting the precursor frozen object into a freeze dryer for vacuum freeze drying, wherein the temperature of a water vapor condenser is below 50 ℃ below zero and the vacuum degree is below 30pa, and obtaining the irregular flower-shaped nano molybdenum disulfide after freeze drying.

FIG. 1 shows SEM (scanning Electron microscope) of spherical nano-molybdenum disulfide particles prepared by vacuum freeze-drying method in example 1, from which MoS (MoS-Moore₂Mainly comprises sheet-shaped structural sheets with similar thickness; microscopically, MoS produced₂Most of them are oriented differently and arranged orderly, and their length and width are far greater than their thickness, and their thickness is about 10 nm.

FIG. 2 shows the SEM photo of the spherical nano-sized molybdenum disulfide particles prepared by vacuum freeze-drying method in example 2, from which the spherical MoS can be seen₂The nanoparticles are prone to agglomeration due to intermolecular forces, hydrogen bonding, electrostatic interactions, and high surface energy of the nanoparticles. Nano MoS with spherical black powder prepared by vacuum freeze drying method₂Particles having an average particle size distribution of about 100 nm.

FIG. 3 shows a transmission electron micrograph of the flower-like nano-molybdenum disulfide particles prepared by the vacuum freeze-drying method in example 3, and it can be seen from the micrograph that the nano-MoS₂Is composed of irregular flower-shaped structures, and the particle size is about 100 nm.

The invention is not limited to the examples, and any equivalent changes to the technical solution of the invention by a person skilled in the art after reading the description of the invention are covered by the claims of the invention.