阅读说明：本技术 一种六方MoTe2纳米片及制备方法 (Hexagonal MoTe2Nanosheet and preparation method ) 是由 祁祥 乔辉 钟建新 于 2020-08-04 设计创作，主要内容包括：本发明提供了一种六方MoTe<Sub>2</Sub>纳米片及其制备方法,所述六方MoTe<Sub>2</Sub>纳米片形貌为六边形的超薄纳米片结构。本发明采用MoO<Sub>3</Sub>和TeO<Sub>2</Sub>氧化剂为前驱物,乙二醇为还原剂,通过液相水热合成的方法制备MoTe<Sub>2</Sub>纳米片,反应过程中通过调控反应温度、时间、pH值可以获得尺寸统一、形貌均匀的六边形的超薄MoTe<Sub>2</Sub>纳米片。本发明是首次通过液相水热合成的方法成功合成了六边形的超薄MoTe<Sub>2</Sub>纳米片。本发明操作简单,反应温度在中低温下进行,对设备要求低,且原料成本低,适合大规模生产。(The invention provides hexagonal MoTe 2 Nanosheet and preparation method thereof, namely hexagonal MoTe 2 The shape of the nanosheet is a hexagonal ultrathin nanosheet structure. The invention adopts MoO 3 And TeO 2 Preparing MoTe by using oxidant as precursor and glycol as reducing agent through liquid-phase hydrothermal synthesis method 2 The hexagonal ultrathin MoTe with uniform size and uniform appearance can be obtained by regulating and controlling the reaction temperature, time and pH value in the reaction process of the nano-sheet 2 Nanosheets. The invention successfully synthesizes hexagonal ultrathin MoTe for the first time by a liquid-phase hydrothermal synthesis method 2 Nanosheets. The method has the advantages of simple operation, low requirement on equipment and low cost of raw materials, and is suitable for large-scale production, and the reaction temperature is carried out at a medium-low temperature.)

1. Hexagonal MoTe₂The preparation method of the nano-sheet is characterized by comprising the following steps: comprises the steps of dissolving PVP in ethylene glycol to obtain PVP-containing ethylene glycol solution, and adding MoO₃Powder, TeO₂Adding the powder and NaOH solution into ethylene glycol solution containing PVP to obtain mixed solution, carrying out hydrothermal reaction on the mixed solution to obtain a product, namely hexagonal MoTe₂Nanosheets.

2. The hexagonal MoTe of claim 1₂The preparation method of the nano-sheet is characterized by comprising the following steps: the solid-liquid mass volume ratio of the polyvinylpyrrolidone to the ethylene glycol is 400mg:15-20 ml.

3. The hexagonal MoTe of claim 1₂The preparation method of the nano-sheet is characterized by comprising the following steps: the MoO₃The solid-liquid mass-volume ratio of the powder to the ethylene glycol is 108 mg:15-20 ml.

4. The hexagonal MoTe of claim 1₂The preparation method of the nano-sheet is characterized by comprising the following steps: in the NaOH solution, the concentration of NaOH is 6-15 mol/L, preferably 7-9 mol/L.

5. The hexagonal MoTe of claim 1₂The preparation method of the nano-sheet is characterized by comprising the following steps: the volume ratio of the NaOH solution to the ethylene glycol is 2: 15-20.

6. The hexagonal MoTe of claim 1₂The preparation method of the nano-sheet is characterized by comprising the following steps: the hydrothermal temperature is 160-220 ℃, and the hydrothermal reaction time is 4-24 h.

7. The hexagonal MoTe of claim 1₂The preparation method of the nano-sheet is characterized by comprising the following steps: completion of hydrothermal reactionThen obtaining a hydrothermal product, sequentially carrying out centrifugal washing on the hydrothermal product by adopting deionized water and absolute ethyl alcohol for times, and carrying out vacuum freeze drying to obtain hexagonal MoTe₂And nanosheets, wherein the centrifugal rotating speed is 6000-10000 rpm.

8. Hexagonal MoTe prepared according to the preparation process of claims 1-7₂Nanosheets.

9. The hexagonal MoTe of claim 8₂A nanoplate characterized by: the hexagonal MoTe₂The shape of the nano sheet is hexagonal.

10. The hexagonal MoTe of claim 8₂A nanoplate characterized by: the hexagonal MoTe₂The side length of the nano sheet is 3-6 μm, and the thickness is less than or equal to 20 nm.

Technical Field

The invention belongs to the field of catalyst preparation and sustainable development of environment and energy, and particularly relates to hexagonal MoTe₂Nanosheets and a method for preparing the same.

Background

Energy is an important substance for the survival and development of human society, and since the twenty-first century, along with the rapid development of productivity, energy crisis and environmental pollution gradually become problems to be solved urgently for human beings. The concern of human beings on the shortage of energy sources in the future and the requirement on environmental protection greatly promote the research on the energy sources, and the conventional catalyst is often limited by low catalytic activity. Therefore, from the viewpoint of commercial interest and practical application, there is a need for further development of inexpensive and effective catalysts.

Since the discovery of the graphene in 2004, the two-dimensional layered material similar to the graphene is widely concerned due to its excellent performance, and compared with the traditional three-dimensional bulk material, the two-dimensional layered material has the advantages of extremely large specific surface area, special electronic structure, high surface carrier transmission rate, good mechanical properties, and the like.

MoTe, a typical two-dimensional nanomaterial₂The semiconductor with the band gap close to Si (1.0 eV) has excellent electron mobility, large surface area, more active sites and good environmental stability, so that the semiconductor has wide application prospect in the fields of environment, energy, photoelectric detection and the like.

Hitherto, MoTe has been prepared₂The methods include a liquid phase stripping method, a mechanical stripping method, a vapor deposition method and an electrochemical deposition method, but most of the methods need high-temperature heat treatment and long reaction time, even some special equipment, and have the defects of easy introduction of impurities and difficult large-scale preparation in the reaction process. Here we prepared hexagonal MoTe by a liquid phase hydrothermal synthesis method₂Nanosheets. The method has simple operation process, low cost and mild reaction conditions (can be carried out at medium and low temperature), and is suitable for large-scale and high-quality synthesis of MoTe₂Nanosheets.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide hexagonal MoTe₂The hexagonal ultrathin MoTe with uniform size and uniform appearance can be prepared by a simple liquid phase synthesis method of the nanosheet and the preparation method thereof₂Nanosheets. The method is simple, easy to operate, low in experimental condition requirement and easy for large-scale preparation.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention relates to hexagonal MoTe₂A process for the preparation of nanoplatelets comprisingThe following steps: dissolving polyvinylpyrrolidone (PVP) solution in ethylene glycol to obtain PVP-containing ethylene glycol solution, and adding MoO₃Powder, TeO₂Adding the powder and NaOH solution into ethylene glycol solution containing polyvinylpyrrolidone (PVP) to obtain mixed solution, carrying out hydrothermal reaction on the mixed solution, and obtaining the product, namely the hexagonal MoTe₂Nanosheets.

In a preferable scheme, the solid-liquid mass volume ratio of the polyvinylpyrrolidone to the ethylene glycol is 400mg:15-20 ml.

In a preferable scheme, a polyvinylpyrrolidone (PVP) solution is stirred in ethylene glycol for 2-6 hours to obtain an ethylene glycol solution containing PVP.

Preferred embodiment, the MoO₃The solid-liquid mass-volume ratio of the powder to the ethylene glycol is 108 mg:15-20 ml.

In the present invention, MoO₃Powder and TeO₂Powder according to end product MoTe₂And (4) proportioning the stoichiometric ratio of the chemical formula.

In a preferable scheme, the concentration of NaOH in the NaOH solution is 6-15 mol/L, preferably 7-10mol/L, and more preferably 9 mol/L.

In a preferred embodiment, the volume ratio of the NaOH solution to the ethylene glycol is 2: 15-20.

Preferably, MoO is used₃、TeO₂And adding the powder and a NaOH solution into a glycol solution containing PVP, and stirring for 30-60 min at room temperature to obtain a mixed solution. The mixed solution obtained after stirring is a clear, transparent and uniform solution.

In a preferable scheme, the hydrothermal temperature is 160-220 ℃, and the hydrothermal reaction time is 4-15 h.

Further preferably, the hydrothermal temperature is 170-190 ℃, and the hydrothermal reaction time is 6-10 h.

In the actual operation process, the mixed solution is placed in a polytetrafluoroethylene lining autoclave, and then is placed in a hydrothermal furnace for heating, and hydrothermal reaction is carried out.

In the preferred scheme, after the hydrothermal reaction is finished, a hydrothermal product is obtained, the hydrothermal product is sequentially subjected to centrifugal washing times by adopting deionized water and absolute ethyl alcohol, and the centrifugal washing times are performed in vacuumFreeze drying to obtain hexagonal MoTe₂And nanosheets, wherein the centrifugal rotating speed is 6000-10000 rpm.

The hexagonal MoTe prepared by the preparation method₂Nanosheets.

The hexagonal MoTe₂The shape of the nano sheet is hexagonal.

The hexagonal MoTe₂The side length of the nano sheet is 3-6 μm, and the thickness is less than or equal to 20 nm.

In the invention, the polyvinylpyrrolidone (PVP) and the MoO are₃、TeO₂The powder and the glycol are industrial products purchased in the market, and the used water is deionized water, so the powder and the glycol have wide sources and low prices.

The principle and the advantages are as follows:

the invention prepares MoTe by a liquid phase synthesis method₂The reaction process of the nano-sheet is mainly divided into four stages (i) MoO is reduced by EG₃And TeO₂(ii) a (ii) Dissolving the Mo and Te crystals and subsequently forming Mo-Te alloy particles; (iii) directionally connecting Mo-Te alloy particles into a hexagonal sheet, wherein the hexagonal sheet consists of a single crystal inner space terminated by a polycrystalline hexagonal frame; (iv) the whole single crystal hexagonal thin slice is formed after the hexagonal frame is transformed into a single crystal through the orientation accessory. The amount of NaOH plays a key role in determining the morphology of the product during the reaction, PVP is used to form MoTe₂The hexagonal crystal plate is used as a stabilizer and a size focusing additive, and a proper amount of NaOH and PVP must be added in the experiment to simultaneously obtain high-purity crystallized MoTe at a certain stable temperature and reaction time₂The invention prepares hexagonal MoTe₂The method has the advantages of simple operation, low requirement on equipment and low cost of raw materials, and is suitable for large-scale production, and the reaction is carried out at medium and low temperature. Prepared ultrathin MoTe₂The nano sheet can be applied to the fields of photocatalytic degradation, optical detection, environmental protection, energy and the like, and has a very wide application prospect.

The invention has the following advantages:

(1) the performance is excellent: the most outstanding advantage of the invention is that the hexagons with uniform size and uniform appearance can be obtained by a simple liquid phase synthesis methodUltra-thin MoTe₂The nano-sheet provides a new approach for the synthesis of transition metal telluride.

(2) The process is simple to operate: the operation process mentioned in the method of the invention has the advantages of easy control of operation conditions, high success rate of preparation, no need of special conditions in the whole preparation process, and no harsh requirements on equipment, and is suitable for large-scale production.

Drawings

FIG. 1 shows MoTe obtained in example 1₂Scanning Electron microscopy (SEM image) of the nanoplates

FIG. 2 shows MoTe obtained in example 2₂SEM image of nanosheet

FIG. 3 shows MoTe obtained in example 3₂Low power SEM images of nanoplates

FIG. 4 shows MoTe obtained in example 3₂High power SEM images of nanoplates

FIG. 5 shows MoTe obtained in example 3₂X-ray diffraction (XRD) pattern of nanosheets

FIG. 6 shows MoTe obtained in example 4₂SEM image of nanosheet

FIG. 7 shows MoTe obtained in example 5₂SEM image of nanosheet

Detailed Description