Method for preparing transition metal chalcogenide heterojunction nanotube with assistance of gold catalyst particles

Abstract

The invention provides a method for realizing the controllable growth of the transition metal chalcogenide heterojunction nanotube by a chemical vapor deposition method assisted by gold catalyst particles, and through magnetron sputtering of a gold nano film and high-temperature annealing treatment, a silicon wafer modified by uniformly distributed gold nano particles with adjustable diameter can be obtained, and the silicon wafer is used as a growth substrate. In the chemical vapor deposition high-temperature reaction process, the proportion and evaporation rate of transition metal oxide powder, sulfur powder and selenium powder are further finely regulated and controlled through a single / double-temperature-zone high-temperature furnace, the flow and proportion of hydrogen and argon are regulated and controlled, and finally controllable growth of the high-crystalline-quality transition metal chalcogenide heterojunction nanotube can be achieved. Furthermore, the growth process of the transition metal chalcogenide nanotube can be obviously influenced by regulating and controlling the temperature of the growth substrate, the type of the evaporation precursor and the evaporation rate, and the transition metal chalcogenide heterojunction nanotube with different structural characteristics such as components and chirality is obtained. Therefore, controllable growth and directional regulation and control of physical properties of the transition metal chalcogenide heterojunction nanotube are realized.

Description

Technical Field

[0001] The invention relates to a method for preparing a transition metal chalcogenide heterojunction nanotube, and realizes controllable growth of the transition metal chalcogenide heterojunction nanotube by a chemical vapor deposition method catalyzed by gold nanoparticles. Background Art

[0002] With the continuous development of the preparation and structural regulation of two-dimensional transition metal chalcogenide (TMD) materials, the research on heterojunctions has received increasing attention. These heterojunctions are formed by stacking different types of TMDs and show rich physical properties, which further promotes the research on TMD physical properties and the exploration of new device applications. In this context, breaking through the traditional TMD structure construction and regulation strategies and finding new research ideas have become the key to promoting the research on transition metal chalcogenide heterojunctions.

[0003] Transition metal chalcogenide heterojunction nanotubes can be regarded as one-dimensional TMD heterostructures formed by nesting different TMD nanotubes. Compared with two-dimensional TMD heterojunctions, one-dimensional TMD heterojunction nanotubes have lower dimensions, smaller Coulomb screening effects, additional bending degrees of freedom, and rich chiral structures, which will enrich the structural regulation mechanism of TMD heterojunctions and produce more novel physical properties and applications.

[0004] In 2021, scientists from the University of Tokyo in Japan proposed a chemical vapor deposition method based on carbon nanotubes as a template to successfully construct TMD heterojunction nanotubes [Science 367, 537–542 (2020).]. However, this preparation method has two defects: 1. The preparation process uses carbon nanotubes as a template, which increases the difficulty and uncertainty of controllable preparation; 2. In the prepared TMD heterojunction nanotubes, carbon nanotubes are relatively stable and are a good conductive material, which is difficult to remove, which limits further optical and electrical research on TMD heterojunction nanotubes. How to obtain relatively pure TMD heterojunction nanotubes through a simpler and more controllable preparation process is the basis for further research.

[0005] Therefore, developing a simple and effective method for preparing TMD heterojunction nanotubes and obtaining pure TMD heterojunction nanotubes, and deeply understanding its physical mechanism and realizing the directional regulation of the structure of TMD heterojunction nanotubes will open up new paths for the research and practical application of transition metal chalcogenide heterojunctions. This will promote the widespread application of transition metal chalcogenide heterojunctions in future electronic and optoelectronic devices and provide an important basis for the exploration of new functional materials. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a gold catalyst particle-assisted chemical vapor deposition method to achieve controllable growth of various transition metal chalcogenide heterojunction nanotubes and finely control parameters such as the composition, number of layers and diameter of the transition metal chalcogenide heterojunction nanotubes. The preparation method is a chemical vapor deposition method assisted by gold catalyst particles. A gold nanoparticle catalyst is obtained by annealing a gold film on a silicon substrate by magnetron sputtering, and the gold nanoparticle catalyst is used as a growth substrate to achieve the growth of transition metal chalcogenide heterojunction nanotubes in an inert atmosphere and at a certain temperature. The obtained transition metal chalcogenide heterojunction nanotubes have uniform tube diameters, controllable diameters, and adjustable internal and external TMD nanotube compositions and number of layers, meeting the requirements of high crystal quality, high yield and chirality-controllable transition metal chalcogenide heterojunction nanotubes.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: The present invention provides a gold catalyst particle-assisted preparation method for realizing the controllable growth of various transition metal chalcogenide heterojunction nanotubes, wherein the catalyst is composed of gold particles, and by controlling the magnetron sputtering coating thickness and the annealing temperature and time, gold nanoparticle catalysts with different diameters and high catalytic activity can be formed after annealing. The preparation steps are as follows: S1: Using high-purity gold as the sputtering target and silicon wafer as the sputtering substrate, sputtering for 35 seconds at 100°C and 50W DC power to obtain a gold film with a uniform thickness of 10nm; S2: The gold film obtained by magnetron sputtering is placed in a high-temperature tube furnace for annealing. The temperature is raised from 25°C to 750°C in 40 minutes during the heating stage, maintained at 750°C for 10 minutes during the constant temperature stage, and cooled to 25°C in 10 minutes during the cooling stage, thereby obtaining a gold nanoparticle catalyst with high catalytic activity and uniform particle diameter; the prepared silicon wafer with gold nanoparticles is placed on a rectangular sample table; S3: Weigh the transition metal oxide and two chalcogenide powders respectively using a quartz boat, spread the transition metal oxide evenly on the quartz boat, and place the chalcogenide powder on the feeding device; S4: placing the transition metal oxide and chalcogen element powders obtained in S3 into specific areas of a high-temperature tube furnace, respectively, and setting a specific heating interval and heating temperature; S5: Set a specific heating interval and heating temperature. When the temperature reaches a certain temperature, start to introduce a certain amount of hydrogen and nitrogen mixed gas. At the same time, use the feeding device to slowly feed the chalcogenide powder into the heating zone to make it reach the initial melting state, and evenly push the chalcogenide powder within a certain period of time until it is completely evaporated.

[0008] S6: When the heat preservation time is over, stop heat preservation, cool naturally to 25°C, take out the sample table, and obtain the finished product.

[0009] Furthermore, the feeding device includes a magnetic base and a magnet. The chalcogenide powder is placed on the magnetic base. The magnet is located outside the high-temperature tube furnace. By moving the magnet, the magnetic base inside the high-temperature tube furnace is driven to move.

[0010] Furthermore, the metal oxide is tungsten trioxide or molybdenum trioxide, and the chalcogen element powder is one of S and Se.

[0011] Compared with the prior art, this application has the following beneficial effects: The gold catalyst particle-assisted preparation method for controllable growth of transition metal chalcogenide heterojunction nanotubes prepares highly active gold nanoparticle catalysts through magnetron sputtering and annealing processes, and has excellent high-temperature stability. The preparation method is simple to prepare, realizes the controllable growth of transition metal chalcogenide heterojunction nanotubes, obtains relatively uniform transition metal chalcogenide heterojunction nanotubes, and can control the temperature of the growth substrate to achieve controllable adjustment of the diameter and number of layers of transition metal chalcogenide heterojunction nanotubes. The new transition metal chalcogenide heterojunction nanotubes have great scientific research and application potential in electronic devices and optoelectronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a SEM image of gold nanoparticles formed on a silicon wafer provided by the present invention; Figure 2 This is a SEM image of the transition metal chalcogenide heterojunction nanotube provided by the present invention. DETAILED DESCRIPTION

[0013] The present invention is further described in detail below by combining implementation examples, but the specific implementation scope is not limited to the examples given. Example 1

[0014] Provided is a method for preparing an inner tube tungsten selenide / outer tube tungsten sulfide heterojunction nanotube, the preparation method comprises two parts: preparation of a gold nanoparticle catalyst and chemical vapor deposition growth, and the preparation steps are as follows: S1: Using high-purity gold as the sputtering target and silicon wafer as the sputtering substrate, sputtering for 35 seconds at 100°C and 50W DC power to obtain a gold film with a uniform thickness of 10nm; S2: The gold film obtained by magnetron sputtering is placed in a high-temperature tube furnace for annealing. The temperature is first raised from 25°C to 750°C in 40 minutes, then kept at 750°C for 10 minutes, and finally dropped to 25°C in 10 minutes, thereby obtaining a gold nanoparticle catalyst with high catalytic activity and uniform particle diameter on the silicon wafer; Figure 1 As shown; the prepared silicon wafer with gold nanoparticles is placed on the rectangular sample stage; S3: Use a quartz boat (15*100) to weigh 0.45g of nano tungsten trioxide (Nanopower<200nm, 99.9% metal base), 0.3g of sublimated sulfur (>99.5%), and 0.4g of selenium powder (>99.5%), spread the tungsten trioxide evenly on the quartz boat, place the sulfur powder on the sulfur powder feeding device, and place the selenium powder on the selenium powder feeding device; S4: Place the quartz boat filled with tungsten trioxide in the center of the single-temperature zone high-temperature tube furnace, place the sample table in the heating zone of the tube furnace, and place the sulfur powder feeding device and selenium powder feeding device in the non-heating zone on the left side of the high-temperature tube furnace; S5: heating the high-temperature tube furnace, raising the temperature from 25°C to 900°C within 40 minutes, when the temperature reaches 900°C, introducing 10sccm of hydrogen and 150sccm of argon from the left side of the high-temperature tube furnace, and adjusting the gas pressure of the high-temperature tube furnace to maintain a constant low pressure; then continue to raise the temperature to 985°C within 4 minutes, and keep it at 985°C for 15 minutes, when the temperature reaches 900°C, use the selenium powder feeding device to slowly feed the selenium powder into the left side of the heating zone of the tube furnace to make it reach the initial melting state, when the temperature reaches 985°C, start, evenly push the selenium powder into the heating zone within 7 minutes, and then evenly push the sulfur powder into the heating zone, and evaporate all the sulfur powder within the next 8 minutes; S6: When the heat preservation time is over, stop heat preservation, cool naturally to 25°C, take out the sample table, and obtain the finished product. Example 2

[0015] Provided is a method for preparing an inner tube molybdenum sulfide / outer tube molybdenum selenide heterojunction nanotube, the preparation method comprises two parts: preparation of a gold nanoparticle catalyst and chemical vapor deposition growth, and the preparation steps are as follows: S1: Using high-purity gold as the sputtering target and silicon wafer as the sputtering substrate, sputtering for 35 seconds at 100°C and 50W DC power to obtain a gold film with a uniform thickness of 10nm; S2: The gold film obtained by magnetron sputtering is placed in a high-temperature tube furnace for annealing. The temperature is first raised from 25°C to 750°C in 40 minutes, then kept at 750°C for 10 minutes, and finally dropped to 25°C in 10 minutes, thereby obtaining a gold nanoparticle catalyst with high catalytic activity and uniform particle diameter on the silicon wafer; Figure 1 As shown; the prepared silicon wafer with gold nanoparticles is placed on the rectangular sample stage; S3: Use a quartz boat (15*100) to weigh 0.5g of nano molybdenum trioxide (Nanopower<200nm, 99.9% metal base), 0.3g of selenium powder (>99.5%) and 0.4g of sublimated sulfur (>99.5%), spread tungsten trioxide evenly on the quartz boat, place selenium powder in front of the feeding device, and place sulfur powder in the back of the feeding device, with a certain distance between sulfur powder and selenium powder; S4: Place the quartz boat filled with molybdenum trioxide in the center of the left temperature zone of the high-temperature tube furnace, place the sample table in the right temperature zone of the tube furnace, and place the feeding device in the non-heating zone on the right side of the high-temperature tube furnace; S5: First heat the right temperature zone of the high-temperature tube furnace, and raise the temperature of the right temperature zone from 25°C to 900°C within 40 minutes. When the right temperature zone starts to heat for 20 minutes, start heating the left temperature zone, and raise the temperature of the center of the left temperature zone of the high-temperature tube furnace from 25°C to 510°C within 20 minutes. When the temperature of the left temperature zone rises to 510°C and the temperature of the right temperature zone rises to 900°C, introduce 13sccm of hydrogen and 150sccm of argon from the left side of the high-temperature tube furnace, and adjust the gas pressure of the high-temperature tube furnace to maintain a constant low pressure; then continue to heat the left and right temperature zones within 4 minutes. The left temperature zone is heated to 580°C and maintained at 580°C for 15 minutes. While the left temperature zone is heated, the right temperature zone is heated to 985°C within 5 minutes and maintained at 985°C for 15 minutes. When the temperature of the right temperature zone reaches 900°C, the selenium powder is slowly fed into the right side of the right temperature zone by the feeding device to make it reach the initial melting state. When the temperature reaches 985°C, the selenium powder on the feeding device is evenly fed into the right temperature zone within 7 minutes. When the selenium powder is evaporated, the sulfur powder on the feeding device is continued to be fed into the right temperature zone, and all the sulfur powder is evaporated within the next 8 minutes.

[0016] S6: When the insulation time of the left temperature zone is over, stop insulation and let the temperature drop naturally to 25°C. When the insulation time of the right temperature zone is over, stop insulation and let the temperature drop naturally to 25°C. Take out the sample table to obtain the finished product.

[0017] The finished products were taken out, and the SEM and TEM test results showed that the grown heterojunction nanotubes had uniform diameters and controllable number of layers, meeting the requirements of high-quality and large-scale growth.

Claims

1. A method for preparing transition metal chalcogenide heterojunction nanotubes assisted by gold catalyst particles, characterized in that: The specific steps are as follows: S1: Using high-purity gold as the sputtering target and silicon wafer as the sputtering substrate, sputtering for 35 seconds at 100°C and 50W DC power to obtain a gold film with a uniform thickness of 10nm; S2: The gold film obtained by magnetron sputtering is placed in a high-temperature tube furnace for annealing. The temperature is raised from 25°C to 750°C in 40 minutes during the heating stage, maintained at 750°C for 10 minutes during the constant temperature stage, and cooled to 25°C in 10 minutes during the cooling stage, thereby obtaining a gold nanoparticle catalyst with high catalytic activity and uniform particle diameter; the prepared silicon wafer with gold nanoparticles is placed on a rectangular sample table; S3: Weigh the transition metal oxide and two chalcogenide powders respectively using a quartz boat, spread the transition metal oxide evenly on the quartz boat, and place the chalcogenide powder on the feeding device; S4: placing the transition metal oxide and chalcogen element powders obtained in S3 into specific areas of a high-temperature tube furnace, respectively, and setting a specific heating interval and heating temperature; S5: Setting a specific heating interval and heating temperature. When the temperature reaches a certain temperature, a certain amount of hydrogen and nitrogen mixed gas is introduced. At the same time, the chalcogenide powder is slowly fed into the heating zone using a feeding device to make it reach an initial melting state. The chalcogenide powder is evenly pushed forward within a certain period of time until it is completely evaporated. S6: When the heat preservation time is over, stop heat preservation, cool naturally to 25°C, take out the sample table, and obtain the finished product.

2. The method according to claim 1, characterized in that The feeding device comprises a magnetic base and a magnet. Chalcogenide powder is placed on the magnetic base. The magnet is located outside the high-temperature tube furnace. By moving the magnet, the magnetic base in the high-temperature tube furnace is driven to move.

3. The method according to claim 1, characterized in that The metal oxide is tungsten trioxide or molybdenum trioxide, and the chalcogen element powder is one of S and Se.

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