Bi / bi2se3 / se core-shell structure nanowire and preparation method thereof

Abstract

The application belongs to the technical field of inorganic materials, and particularly relates to a Bi / Bi2Se3 / Se core-shell structure nanowire and a preparation method thereof. The nanowire structure features that from inside to outside, it is a Bi wire / Bi2Se3 shell / Se quantum dot. The application provides a preparation method of the Bi / Bi2Se3 / Se core-shell structure nanowire. The Bi / Bi2Se3 / Se core-shell structure nanowire is prepared by using a simple chemical vapor deposition method, taking Bi and Bi2Se3 powders as growth sources, taking a silicon wafer (Si) coated with a gold (Au) film as a growth substrate, and heating to a certain temperature under the condition that an inert gas is used as a carrier gas. Meanwhile, the prepared Bi / Bi2Se3 / Se core-shell structure nanowire not only has a unique heterostructure, but also has a regular shape and presents a typical one-dimensional feature. The special interface formed by the core-shell layer and the nanowire / quantum dot heterostructure in the composite structure endows the Bi / Bi2Se3 / Se core-shell structure nanowire with unique functional characteristics. In addition, the preparation method provided by the application has simple steps, can realize rapid and large-scale synthesis, has less environmental pollution, is simple to operate, and has strong generalizability. Therefore, the application has important research value and wide application potential.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of inorganic materials, and particularly relates to a Bi / Bi2Se3 / Se core-shell structure nanowire and a preparation method thereof. BACKGROUND

[0002] Nanomaterials have different physical and chemical properties from conventional bulk materials due to the significant surface effect and quantum size effect caused by the similar spatial geometric size to the characteristic wavelength of micro-particles and quasi-particles. Among them, one-dimensional nanostructures (including nanotubes, nanowires and nanorods) have shown wide application potential in the fields of electronic devices, supercapacitors, LEDs and sensors due to their special surface characteristics and unique electronic and optical properties. In the past decade, researchers have successfully synthesized a large number of one-dimensional nanomaterials by using various technologies, and have made in-depth research on their structure, properties and growth mechanism.

[0003] At the same time, researchers not only pay attention to the single material properties of one-dimensional nanostructures, but also actively explore the way of combining different materials to build heterojunctions to enhance their performance and functions. For example, core-shell structure is a kind of heterostructure composed of two or more materials by a specific process. This kind of structure not only retains the physical and chemical properties of the core and shell materials, but also realizes novel functional characteristics by using the unique interface formed between different materials, thereby further expanding the application field of materials. Therefore, core-shell structure has gradually become an important direction in the research of nanomaterials. In addition, with the in-depth research, nanowire / quantum dot heterostructure as a new type of interface structure gradually enters the field of view of researchers. This composite structure takes nanowire as the carrier and loads quantum dots, which not only improves the intrinsic performance of nanowire, but also endows it with new functional characteristics. Quantum dots, as a zero-dimensional semiconductor structure, can confine carriers in three dimensions, so they have excellent luminescent properties. After combining with quantum dots, the nanowire which combines the functions of waveguide and resonant cavity can realize the gain, conduction and regulation of photons on the nanoscale, so this composite heterostructure is considered as an ideal choice for the construction of high-quality optoelectronic devices.

[0004] In recent years, (Bi2) m (Bi2Se3) nThe topological insulator material of the series of (wherein m and n are integers) has attracted more and more researchers' attention due to its unique layered heterostructure and excellent electrical transport performance. At present, the one-dimensional nano core-shell structure of the material is rarely studied, and for the topological insulator, the nano structure with high specific surface area is helpful to avoid the interference of the bulk state on the surface state, and is an ideal choice for studying the topological properties. In addition, the special interface generated by the core-shell structure and the nano wire / quantum dot heterostructure composed of different materials also exhibits unique functional characteristics. Se is a common photoelectric semiconductor material and has been widely used in the market. Therefore, it is of important research significance and potential application value to grow the Bi / Bi2Se3 / Se core-shell structure nano wire with a heterostructure. SUMMARY

[0005] In order to overcome the above-mentioned deficiencies of the prior art, the application provides a preparation method of a Bi / Bi2Se3 / Se core-shell structure nano wire.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the application is:

[0007] The first aspect of the application provides a preparation method of a Bi / Bi2Se3 / Se core-shell structure nano wire, comprising the following steps:

[0008] S1, using Bi and Bi2Se3 powders as growth sources, using a silicon wafer (Si) coated with an Au film as a growth substrate, then placing the Bi2Se3 powder in the heating center of the reaction area of a chemical vapor deposition device, placing the Bi powder upstream of the heating center, and placing the Si substrate downstream of the heating center;

[0009] S2, excluding oxygen in the reaction area, then inputting an inert gas as a carrier gas, maintaining the gas pressure of the reaction area in a certain range, and then heating to a certain temperature to prepare the Bi / Bi2Se3 / Se core-shell structure nano wire through reaction.

[0010] The application uses a simple chemical vapor deposition method, uses Bi and Bi2Se3 powders as growth sources, uses a silicon wafer coated with an Au film as a growth substrate, and heats to a certain temperature under the condition that an inert gas is used as a carrier gas to prepare a Bi / Bi2Se3 / Se core-shell structure nano wire through reaction.

[0011] Preferably, in step S1, the mass ratio of the Bi and Bi2Se3 powders is 1:2.

[0012] Preferably, in step S1, the Bi powder is 2-6 cm away from the heating center, and the Si substrate plated with Au film is 8-13 cm away from the heating center.

[0013] More preferably, the Bi powder is 3-4 cm away from the heating center, and the Si substrate plated with Au film is 9-12 cm away from the heating center.

[0014] Preferably, in step S2, the reaction temperature is 630-670℃, and the reaction time is 0.5-3 h.

[0015] More preferably, the reaction temperature is 640-660℃, and the reaction time is 1-2 h.

[0016] Preferably, in step S2, the inert gas argon (Ar) is controlled at a flow rate of 30-90 sccm.

[0017] Preferably, in step S2, the gas pressure in the reaction area is maintained below 200 Pa.

[0018] The second aspect of the present application provides a Bi / Bi2Se3 / Se core-shell structure nanowire prepared by the preparation method of the first aspect.

[0019] The Bi / Bi2Se3 / Se core-shell structure nanowire prepared by the present application has a unique core-shell structure and nanowire / quantum dot heterostructure, and is regular in morphology and has a typical one-dimensional feature. The length of the nanowire is about 50-300 μm, and the diameter is about 100-800 nm. This special heterostructure and large length-diameter ratio not only endow the nanowire with unique functional properties, but also have important research significance and potential application value.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] This invention provides a method for preparing Bi / Bi2Se3 / Se core-shell nanowires. Using Bi and Bi2Se3 powders as growth sources and a silicon wafer (Si) coated with an Au film as the growth substrate, the distance between the Si substrate and the heating center is adjusted, and the nanowires are heated to a certain temperature under an inert gas as the carrier gas, resulting in a reaction. The prepared Bi / Bi2Se3 / Se core-shell nanowires possess a unique core-shell structure and a nanowire / quantum dot heterostructure, exhibiting regular morphology and typical one-dimensional characteristics. Furthermore, the prepared Bi / Bi2Se3 / Se core-shell nanowires have a length of approximately 50–300 μm and a diameter of approximately 100–800 nm. This unique heterostructure and large aspect ratio endow them with unique functional properties, expanding their application range. In addition, this invention employs a chemical vapor deposition process to grow Bi / Bi2Se3 / Se core-shell nanowires. The process is simple, enabling rapid and large-scale synthesis with minimal environmental pollution and easy operation, making it highly scalable. Therefore, this invention has significant research value and broad application potential. Attached Figure Description

[0022] Figure 1 X-ray diffraction pattern of Bi / Bi2Se3 / Se core-shell structured nanowires from Example 1;

[0023] Figure 2 This is a scanning electron microscope (SEM) image of the Bi / Bi2Se3 / Se core-shell structured nanowire from Example 1.

[0024] Figure 3 This is a transmission electron microscope (TEM) image of the Bi / Bi2Se3 / Se core-shell structured nanowire from Example 1.

[0025] Figure 4 The image shows a transmission electron microscope (TEM) image of the nanowires from Comparative Example 1. Detailed Implementation

[0026] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0028] Example 1

[0029] (1) Take 0.1 g of Bi powder and 0.2 g of Bi2Se3 powder respectively into different canisters as growth sources, and place several pieces of cleaned silicon wafer (Si) coated with Au film as growth substrate on the inverted canister;

[0030] (2) Place the canister containing Bi2Se3 powder in the heating center of the reaction device (chemical vapor deposition equipment, instrument name: high-temperature tube furnace, model: GSL-1700X, manufacturer: Hefei Kechuang Material Technology Co., Ltd.), and place the canister containing Bi powder 3 cm upstream of the heating center, and place the inverted canister containing Si substrate 8-13 cm downstream of the heating center (8, 9, 10, 11, 12, 13 cm respectively) from the heating center;

[0031] (3) Close the flange, open the mechanical pump to vacuum the inside of the reaction device, then introduce the carrier gas argon (Ar) to adjust the gas flow to 60 sccm, and maintain the vacuum reading below 200 pa;

[0032] (4) Set the heating rate to 10℃ / min, heat to 650℃ and keep for 2 hours, then cool to room temperature, turn off the heating switch and gas, and take out the sample, to prepare Bi / Bi2Se3 / Se core-shell structure nanowires.

[0033] The Bi / Bi2Se3 / Se core-shell structure nanowires prepared in Example 1 were subjected to X-ray diffraction analysis, and the analysis results are shown in Figure 1 The main phase of the sample matches Bi2Se3 (PDF #33-0214), and the orientation is obvious, and the strong diffraction peak corresponds to (006) and (0015) crystal faces, indicating that the synthesized product mainly grows along the c-axis.

[0034] The Bi / Bi2Se3 / Se core-shell structure nanowires prepared in Example 1 were subjected to scanning electron microscopy (SEM) analysis, and the analysis results are shown in Figure 2 From Figure 2 (a) can be found that the length of the product is about 50-300 μm, from Figure 2 (b), (c) can be seen that the product has a regular shape and a typical one-dimensional feature, and the top of the nanowire has Au particles and the surface has Se quantum dots.

[0035] The Bi / Bi2Se3 / Se core-shell structure nanowires prepared in Example 1 were subjected to transmission electron microscopy (TEM) analysis, and the analysis results are shown in Figure 3 As shown in Figure 3The element composition of the Bi / Bi2Se3 / Se core-shell structure nanowire is shown, and it can be clearly found that the nanowire structure features are Bi wire / Bi2Se3 shell / Se quantum dot from inside to outside, forming a core / shell / quantum dot heterostructure.

[0036] Comparative Example 1

[0037] The preparation method is the same as that in Example 1, except that the growth source in Example 1 is replaced by only Bi2Se3 powder without Bi powder, and other conditions are the same.

[0038] The product prepared in Comparative Example 1 is subjected to transmission electron microscopy (TEM) analysis, and the analysis results are shown in Figure 4 Figure 4 The morphology and element composition of the product are shown, and it can be clearly seen that the nanowire surface is smooth and flat without quantum dots, and the element distribution is uniform without special core-shell structure.

[0039] Comparative Example 2

[0040] The preparation method is the same as that in Example 1, except that the distance between the Si substrate and the heating center in Example 1 is changed to 3-7 cm and 14-18 cm (3, 4, 5, 6, 7 cm and 14, 15, 16, 17, 18 cm, respectively), and other conditions are the same.

[0041] The results show that when the Si substrate is 3-7 cm and 14-18 cm away from the heating center, almost no product with obvious one-dimensional characteristics is generated.

[0042] Comparative Example 3

[0043] The preparation method is the same as that in Example 1, except that the reaction temperature in Example 1 is changed to 600-620℃ and 680-700℃, respectively, and other conditions are the same.

[0044] The results show that when the reaction temperature is 600-620℃, the product is less, and almost no product with obvious one-dimensional characteristics is generated; when the reaction temperature is 680-700℃, the growth effect is poor, and the length of the nanowire is greatly shortened.

[0045] Comparative Example 4

[0046] The preparation method is the same as that in Example 1, except that the reaction time in Example 1 is changed to 30 min, and other conditions are the same.

[0047] The results show that although the growth effect is slightly different, the product is still a Bi / Bi2Se3 / Se core-shell structure nanowire.

[0048] Comparative Example 5​

[0049] The preparation method is same with example 1, except that the reaction time in example 1 is changed to 3h respectively, for setting a control group for comparison, and other conditions are same.

[0050] The results show that the growth effect is slightly different, but the product is still Bi / Bi2Se3 / Se core-shell structure nanowire.

[0051] Comparative example 6

[0052] The preparation method is same with example 1, except that the gas flow in example 1 is changed to 30sccm, for setting a control group for comparison, and other conditions are same.

[0053] The results show that the growth effect is slightly different, but the product is still Bi / Bi2Se3 / Se core-shell structure nanowire.

[0054] Comparative example 7

[0055] The preparation method is same with example 1, except that the gas flow in example 1 is changed to 90sccm, for setting a control group for comparison, and other conditions are same.

[0056] The results show that the growth effect is slightly different, but the product is still Bi / Bi2Se3 / Se core-shell structure nanowire.

[0057] As can be seen from the above, the Bi / Bi2Se3 / Se core-shell structure nanowire is prepared by using simple chemical vapor deposition method, using Bi powder and Bi2Se3 powder as growth source, using silicon wafer (Si) plated with Au film as growth substrate, and heating to a certain temperature under the condition of inert gas as carrier gas. The prepared Bi / Bi2Se3 / Se core-shell structure nanowire has unique core-shell structure and nanowire / quantum dot heterostructure, and has regular morphology and typical one-dimensional characteristics. The length of the nanowire is about 50-300μm, and the diameter is about 100-800nm. The special heterostructure and large length-diameter ratio endow the nanowire with unique functional characteristics and expand its application range. Therefore, the present application has important research value and broad application potential.

[0058] The embodiments of the present application are described in detail above, but the present application is not limited to the described embodiments. For those skilled in the art, various changes, modifications, replacements and variations of the embodiments are made without departing from the principles and spirits of the present application, and still fall within the protection scope of the present application.

Claims

1. A method for preparing Bi / Bi2Se3 / Se core-shell structured nanowires, characterized in that, Includes the following steps: S1. Using Bi and Bi2Se3 powders as growth sources, and a silicon wafer (Si) coated with a gold (Au) film as a growth substrate, the Bi2Se3 powder is placed in the heating center of the reaction zone of the chemical vapor deposition equipment, the Bi powder is placed upstream of the heating center, 2-6 cm away from the heating center; the Si substrate is placed downstream of the heating center, 8-13 cm away from the heating center. S2. Remove oxygen from the reaction area and introduce an inert gas as a carrier gas. After maintaining the gas pressure in the reaction area within a certain range, heat to 630~670 ℃ and prepare Bi / Bi2Se3 / Se core-shell structured nanowires through the reaction. The core-shell structured nanowires are composed of Bi wire / Bi2Se3 shell / Se quantum dots from the inside to the outside.

2. The method for preparing Bi / Bi₂Se₃ / Se core-shell structured nanowires according to claim 1, characterized in that, In step S1, the mass ratio of Bi and Bi2Se3 powder is 1:

2.

3. The method for preparing Bi / Bi2Se3 / Se core-shell structured nanowires according to claim 1, characterized in that, In step S1, the Bi powder is 3-4 cm away from the heating center, and the Si substrate coated with Au film is 9-12 cm away from the heating center.

4. The method for preparing Bi / Bi₂Se₃ / Se core-shell structured nanowires according to claim 1, characterized in that, In step S2, the reaction temperature is 630~670 ℃ and the time is 0.5~3 h.

5. The method for preparing Bi / Bi2Se3 / Se core-shell structured nanowires according to claim 4, characterized in that, The reaction temperature is 640~660 ℃ and the time is 1~2 h.

6. The method for preparing Bi / Bi2Se3 / Se core-shell structured nanowires according to claim 1, characterized in that, In step S2, the inert gas includes argon (Ar), and the gas flow rate is controlled at 30~90 sccm.

7. The method for preparing Bi / Bi₂Se₃ / Se core-shell structured nanowires according to claim 1, characterized in that, In step S2, the gas pressure in the reaction zone is maintained below 200 Pa.

8. Bi / Bi2Se3 / Se core-shell structured nanowires prepared by the preparation method according to any one of claims 1-7.

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