Bi / Bi2Se3 / Se core-shell structure nanowire and preparation method thereof

Abstract

The invention 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 is structurally characterized by sequentially comprising a Bi wire, a Bi2Se3 shell layer and Se quantum dots from inside to outside. The invention provides a preparation method of a Bi / Bi2Se3 / Se core-shell structure nanowire, which is prepared by using a simple chemical vapor deposition method, taking Bi and Bi2Se3 powder as a growth source, taking a silicon wafer (Si) plated with a gold (Au) film as a growth substrate, heating to a certain temperature under the condition of taking inert gas as carrier gas, and then reacting. Meanwhile, the prepared Bi / Bi2Se3 / Se core-shell structure nanowire not only has a unique heterostructure, but also is regular in form, and shows typical one-dimensional characteristics. A special interface formed by the core-shell layer and the nanowire / quantum dot heterostructure in the composite structure endows the composite structure with unique functional characteristics. In addition, the preparation method provided by the invention is simple and convenient in steps, capable of realizing rapid and massive synthesis, relatively low in environmental pollution, simple and convenient to operate and relatively high in generalizability. Therefore, the invention has important research value and wide application potential.

Description

Technical Field

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

[0002] Nanomaterials have significant surface effects, quantum size effects and other properties due to their spatial geometric dimensions being similar to the characteristic wavelengths of microscopic particles and quasiparticles such as electrons and phonons, thus showing physical and chemical properties that are different from those of conventional bulk materials. Among them, one-dimensional nanostructures (including nanotubes, nanowires and nanorods) have shown broad application potential in electronic devices, supercapacitors, LEDs and sensors due to their special surface features and unique electronic and optical properties. Over the past decade, researchers have successfully synthesized a large number of one-dimensional nanomaterials using a variety of techniques, and have conducted in-depth studies on their structures, properties and growth mechanisms.

[0003] At the same time, researchers not only focus on the single material properties of one-dimensional nanostructures, but also actively explore ways to combine different materials to construct heterojunctions to enhance their performance and functions. For example, the core-shell structure is a heterostructure formed by combining two or more materials through a specific process. This type of structure not only retains the physical and chemical properties of the core and shell materials, but also uses the unique interface formed between different materials to achieve novel functional characteristics, thereby further expanding the application field of the material. Therefore, the core-shell structure has gradually become an important direction in nanomaterial research. In addition, with the deepening of research, nanowire / quantum dot heterostructures have gradually entered the field of vision of scientific researchers as a new type of interface structure. This composite structure uses nanowires as carriers and loads quantum dots, which not only improves the bulk performance of nanowires, but also gives them new functional characteristics. Quantum dots, as a zero-dimensional semiconductor structure, can constrain carriers in three dimensions, and therefore have excellent luminescence characteristics. After the nanowires that combine the functions of waveguides and resonant cavities are composited with quantum dots, they can achieve gain, conduction and regulation of photons at the nanoscale, making this composite heterostructure an ideal choice for the construction of high-quality optoelectronic devices.

[0004] In recent years, (Bi2) m (Bi2Se3) n(where m and n are integers) series of topological insulating materials have attracted more and more researchers' attention due to their unique layered heterogeneous crystal structure and excellent electrical transport properties. At present, there is little research on the one-dimensional nano core-shell structure of this series of materials. For topological insulators, nanostructures with high specific surface area help avoid the interference of bulk states on surface states, which is an ideal choice for studying their topological properties. In addition, the special interfaces generated by the core-shell structure and nanowire / quantum dot heterostructure composed of different materials also show unique functional properties. Se is a common optoelectronic semiconductor material and has been widely used in the market. Therefore, the growth of Bi / Bi2Se3 / Se core-shell structure nanowires with heterostructures has important research significance and potential application value. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a method for preparing Bi / Bi2Se3 / Se core-shell structured nanowires. The structural characteristics of the prepared nanowires are Bi wire / Bi2Se3 shell / Se quantum dots from the inside to the outside. The nanowires not only have regular morphology and present typical one-dimensional characteristics, but also have unique heterogeneous structures and form special interfaces, which give them unique functional characteristics and have important application potential.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] The first aspect of the present invention provides a method for preparing Bi / Bi2Se3 / Se core-shell structure nanowires, comprising the following steps:

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

[0009] S2. Expel oxygen from the reaction area, then input an inert gas as a carrier gas, maintain the gas pressure in the reaction area within a certain range, heat to a certain temperature and react to prepare Bi / Bi2Se3 / Se core-shell structure nanowires.

[0010] The present invention utilizes a simple chemical vapor deposition method, uses Bi and Bi2Se3 powder 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 of an inert gas as a carrier gas to prepare a Bi / Bi2Se3 / Se core-shell structure nanowire 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 to 6 cm away from the heating center, and the Si substrate coated with the Au film is 8 to 13 cm away from the heating center.

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

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

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

[0016] Preferably, in step S2, the inert gas argon (Ar) has a gas flow rate controlled at 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 invention provides Bi / Bi2Se3 / Se core-shell structure nanowires prepared by the preparation method described in the first aspect.

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

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

[0021] The invention provides a method for preparing Bi / Bi2Se3 / Se core-shell structure nanowires, wherein Bi and Bi2Se3 powders are used as growth sources, a silicon wafer (Si) coated with an Au film is used as a growth substrate, and after adjusting the distance between the Si substrate and the heating center, the Si substrate is heated to a certain temperature under the condition of an inert gas as a carrier gas and then reacted to obtain the Bi / Bi2Se3 / Se core-shell structure nanowires. The prepared Bi / Bi2Se3 / Se core-shell structure nanowires have a unique core-shell structure and a nanowire / quantum dot heterostructure, and have a regular morphology and typical one-dimensional characteristics. At the same time, the prepared Bi / Bi2Se3 / Se core-shell structure nanowires have a length of about 50 to 300 μm and a diameter of about 100 to 800 nm. This special heterostructure and a large aspect ratio give it unique functional characteristics and expand its application range. In addition, the invention adopts a chemical vapor deposition method to grow a process for Bi / Bi2Se3 / Se core-shell structure nanowires, which has simple steps, can achieve rapid and large-scale synthesis, and has less environmental pollution, is easy to operate, and has strong scalability. Therefore, the present invention has important research value and broad application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the X-ray diffraction pattern of Bi / Bi2Se3 / Se core-shell structure nanowires in Example 1;

[0023] Figure 2 This is a scanning electron microscope (SEM) image of Bi / Bi2Se3 / Se core-shell structure nanowires in Example 1;

[0024] Figure 3 This is a transmission electron microscope (TEM) image of the Bi / Bi2Se3 / Se core-shell structure nanowires of Example 1;

[0025] Figure 4 This is a transmission electron microscope (TEM) image of the nanowires of the product of Comparative Example 1; DETAILED DESCRIPTION

[0026] The specific embodiments of the present invention are further described below. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.

[0028] Example 1

[0029] (1) Weigh 0.1 g of Bi powder and 0.2 g of Bi2Se3 powder and place them in different boats as growth sources, and place several cleaned Au-film-coated silicon (Si) substrates on the inverted boats as growth substrates;

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

[0031] (3) Close the flange, turn on the mechanical pump to evacuate the interior of the reaction device to a vacuum state, then introduce carrier gas argon (Ar), adjust the gas flow rate to 60 sccm, and maintain the vacuum reading below 200 Pa;

[0032] (4) The heating rate was set at 10°C / min, and the sample was heated to 650°C and kept at this temperature for 2 hours, then cooled to room temperature with the furnace, the heating switch and the gas were turned off, and the sample was taken out to obtain Bi / Bi2Se3 / Se core-shell structured nanowires.

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

[0034] The Bi / Bi2Se3 / Se core-shell structure nanowires prepared in Example 1 were analyzed by scanning electron microscopy (SEM). Figure 2 As shown, from Figure 2 (a) It can be found that the product length ranges from about 50 to 300 μm. Figure 2 (b) and (c) show that the product has a regular morphology and typical one-dimensional characteristics, with Au particles at the top of the nanowires and Se quantum dots on the surface.

[0035] The Bi / Bi2Se3 / Se core-shell structure nanowires prepared in Example 1 were analyzed by transmission electron microscopy (TEM). Figure 3 As shown, Figure 3The elemental composition of the Bi / Bi2Se3 / Se core-shell structured nanowires is shown. It can be clearly seen that the structural characteristics of the nanowires are Bi wire / Bi2Se3 shell / Se quantum dots from the inside to the 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 with only Bi2Se3 powder without Bi powder, which is used to set up a control group for comparison, and other conditions are the same.

[0038] The product prepared in Comparative Example 1 was subjected to transmission electron microscopy (TEM) analysis, and the analysis results are as follows: Figure 4 As shown, Figure 4 The morphology and elemental composition of the product are displayed. It can be clearly seen that the surface of the nanowires is smooth and flat, there are no quantum dots, and the elements are evenly distributed without any 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) for setting up a control group for comparison, and the 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 products with obvious one-dimensional characteristics are generated.

[0042] Comparative Example 3

[0043] The preparation method is the same as that in Example 1, except that the reaction temperatures in Example 1 are changed to 600-620° C. and 680-700° C., respectively, for setting up a control group for comparison, and other conditions are the same.

[0044] The results show that when the reaction temperature is 600-620℃, the products are less and almost no products with obvious one-dimensional characteristics are generated; when the reaction temperature is 680-700℃, the growth effect is poor and the length of the nanowires 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 for setting up a control group for comparison, and the other conditions are the same.

[0047] The results show that although the growth effects are slightly different, the product is still Bi / Bi2Se3 / Se core-shell structured nanowires.

[0048] Comparative Example 5

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

[0050] The results show that although the growth effects are slightly different, the product is still Bi / Bi2Se3 / Se core-shell structured nanowires.

[0051] Comparative Example 6

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

[0053] The results show that although the growth effects are slightly different, the product is still Bi / Bi2Se3 / Se core-shell structured nanowires.

[0054] Comparative Example 7

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

[0056] The results show that although the growth effects are slightly different, the product is still Bi / Bi2Se3 / Se core-shell structured nanowires.

[0057] In summary, the present invention uses a simple chemical vapor deposition method, using Bi powder and Bi2Se3 powder as growth sources, using a silicon wafer (Si) coated with an Au film as a growth substrate, heating to a certain temperature under the condition of an inert gas as a carrier gas, and then reacting to prepare a Bi / Bi2Se3 / Se core-shell structure nanowire. The prepared Bi / Bi2Se3 / Se core-shell structure nanowire has a unique core-shell structure and a nanowire / quantum dot heterostructure, and has a regular morphology and typical one-dimensional characteristics. The length of the nanowire is about 50 to 300 μm, and the diameter is about 100 to 800 nm. This special heterostructure and large aspect ratio give it unique functional characteristics and expand its application range. Therefore, the present invention has important research value and broad application potential.

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

Claims

1. A method for preparing Bi / Bi2Se3 / Se core-shell structure nanowires, characterized in that: The following steps are involved: S1, using Bi and Bi2Se3 powders as growth sources, and using a silicon wafer (Si) coated with a gold (Au) film as a growth substrate, then placing the Bi2Se3 powder at the heating center of the reaction area of ​​the chemical vapor deposition equipment, the Bi powder at the upstream of the heating center, and the Si substrate at the downstream of the heating center; S2. Expel oxygen from the reaction area, then input an inert gas as a carrier gas, maintain the gas pressure in the reaction area within a certain range, heat to a certain temperature and react to prepare Bi / Bi2Se3 / Se core-shell structure nanowires.

2. The method for preparing Bi / Bi2Se3 / Se core-shell structure nanowires according to claim 1, characterized in that: The obtained nanowire structure features Bi wire / Bi2Se3 shell / Se quantum dots from inside to outside.

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

2.

4. The method for preparing Bi / Bi2Se3 / Se core-shell structure nanowires according to claim 1, characterized in that: In step S1, the Bi powder is 2 to 6 cm away from the heating center, and the Si substrate coated with the Au film is 8 to 13 cm away from the heating center.

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

6. The method for preparing Bi / Bi2Se3 / Se core-shell structure nanowires according to claim 1, characterized in that: In step S2, the reaction temperature is 630-670° C. and the reaction time is 0.5-3 h.

7. The method for preparing Bi / Bi2Se3 / Se core-shell structure nanowires according to claim 6, characterized in that: The reaction temperature is 640-660°C and the reaction time is 1-2h.

8. The method for preparing Bi / Bi2Se3 / Se core-shell structure 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.

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

10. Bi / Bi2Se3 / Se core-shell structure nanowires prepared by the preparation method according to any one of claims 1 to 9.

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