Method for preparing single-layer molybdenum disulfide / tungsten disulfide two-component gradient material in one step

Abstract

The present application relates to a method for preparing single-layer MoS2 / WS2 two-component gradient material by one-step method, and belongs to the field of inorganic nano semiconductor materials. Sulfur powder is compacted on one side of a corundum boat with a spoon, and the corundum boat containing the sulfur powder is sealed with aluminum foil paper. A small hole is punched on the side containing the sulfur powder with a thin steel needle, and then the corundum boat containing the sulfur powder is placed in the upstream low-temperature zone of a multi-zone tube furnace. A mixture of tungsten oxide powder and NaCl and molybdenum oxide powder are placed separately in the upstream of a long corundum boat, and a substrate is placed in the downstream of the long corundum boat. Then the long corundum boat is placed in the downstream high-temperature zone of the multi-zone tube furnace. With the adjustment of the temperature of the downstream high-temperature zone of the multi-zone tube furnace and the adjustment of the amount of NaCl, single-layer MoS2 / WS2 two-component gradient materials of different sizes are prepared. The present application can prepare single-layer MoS2 / WS2 two-component gradient materials with controllable size. The prepared samples have good crystallinity, stable chemical and thermodynamic properties, and good application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to a one-step method for preparing a single-layer MoS2 / WS2 two-component gradient material, and belongs to the field of inorganic nanometer semiconductor materials. BACKGROUND

[0002] Chemical vapor deposition has unique advantages in the field of two-dimensional material preparation, and the prepared samples have high purity and good crystallinity. A variety of two-dimensional materials have been prepared by this method, greatly enriching the family of two-dimensional materials. Two-dimensional chalcogenides are a common type of two-dimensional materials that can be prepared by chemical vapor deposition, and researchers have gained some understanding of their structure and properties. Not only single two-dimensional chalcogenides, but also two-dimensional chalcogenide heterojunctions are often reported. Based on the maturity of the preparation process of single two-dimensional chalcogenides, researchers have conducted a detailed study from large size to small size. Comparative studies of two-dimensional chalcogenide horizontal heterojunctions of different sizes are relatively rare, and the reason is more in the preparation process of two-dimensional chalcogenide horizontal heterojunctions, which is more complex and has poor size controllability. The present application aims to solve the existing problems, and combines flux-assisted growth and temperature regulation to prepare size-controllable single-layer MoS2 / WS2 two-component gradient materials by horizontal spatial anchoring limited growth method, which lays a solid foundation for the study of single-layer MoS2 / WS2 two-component gradient materials of different sizes.

[0003] The present application can prepare single-layer MoS2 / WS2 two-component gradient materials with a size of about 5-80 μm. Large size can be used for the study of electronics and optoelectronics. Small size has reduced grain size, resulting in increased heterojunction density and increased grain boundary density, which synergistically act on the study of electrocatalysis, photoelectrocatalysis, photocatalysis, biosensing and other fields. SUMMARY

[0004] The purpose of the present application is to provide a one-step method for preparing a single-layer MoS2 / WS2 two-component gradient material, which has simple preparation steps, easy operation, fast synthesis speed, good crystallinity, stable chemical and thermodynamic properties, and good application prospect.

[0005] In order to achieve the above purpose, the technical scheme adopted by the present application is:

[0006] A method for preparing single-layer MoS2 / WS2 dual-component gradient material in one step, wherein sulfur powder is compacted on one side of a corundum boat with a spoon, the corundum boat containing the sulfur powder is sealed with aluminum foil, two to three small holes with a diameter of 0.5 mm are punched on the side containing the sulfur powder with a thin steel needle, and then the corundum boat containing the sulfur powder is placed in the upstream low-temperature zone of a multi-zone tube furnace; a mixture of tungsten oxide powder and NaCl and molybdenum oxide powder are placed in a long corundum boat in sequence, a deposited substrate is placed downstream of the long corundum boat, and then the long corundum boat is placed in the downstream high-temperature zone of the multi-zone tube furnace; with the adjustment of the temperature of the downstream high-temperature zone of the multi-zone tube furnace and the adjustment of the amount of NaCl mixed with the tungsten oxide powder, single-layer MoS2 / WS2 dual-component gradient materials with different sizes are prepared.

[0007] The further improvement of the technical scheme of the present application is that the mass of the sulfur powder is 0.5-2.0 g, the mass of the tungsten oxide powder is 0.5-1.5 g, and the mass of the molybdenum oxide is 0.1-0.5 g.

[0008] The further improvement of the technical scheme of the present application is that the two corundum boats are placed 2 cm away from the heat resistance wire of the multi-zone tube furnace and are located downstream of the resistance wire.

[0009] The further improvement of the technical scheme of the present application is that the length of the corundum boat containing the sulfur powder is 3-6 cm, the length of the long corundum boat is 15-25 cm, and the height of the long corundum boat is 1.0-1.2 cm.

[0010] The further improvement of the technical scheme of the present application is that the deposited substrate is placed 4-7 cm away from the molybdenum oxide powder, and the silicon dioxide is placed with the bottom facing down; the width of the bottom of the long corundum boat is 0.9-0.95 cm, and the bottom is concave downward.

[0011] The further improvement of the technical scheme of the present application is that the temperature control range of the upstream low-temperature zone of the multi-zone tube furnace is 160-210 DEG C.

[0012] The further improvement of the technical scheme of the present application is that the size of the single-layer MoS2 / WS2 dual-component gradient material is determined by the temperature of the downstream high-temperature zone of the multi-zone tube furnace and the amount of NaCl; when the temperature of the downstream high-temperature zone of the multi-zone tube furnace is greater than or equal to 750 DEG C and less than 800 DEG C, and the amount of NaCl is 1-3 mg, the size of the prepared single-layer MoS2 / WS2 dual-component gradient material is 50-80 mu m; when the temperature of the downstream high-temperature zone of the multi-zone tube furnace is greater than or equal to 800 DEG C and less than 890 DEG C, and the amount of NaCl is 0.1-0.2 mg, the size of the prepared single-layer MoS2 / WS2 dual-component gradient material is 80-100 mu m. S2The size of the two-component gradient material is 20-30 mu m; when the temperature of the high-temperature zone downstream of the multi-temperature zone tube furnace is greater than or equal to 890 DEG C and less than 960 DEG C, and the amount of NaCl is less than 0.1 mg, the size of the prepared MoS2 / WS2 two-component gradient material is 5-10 mu m.

[0013] The further improvement of the technical scheme of the present application is that the higher the temperature of the high-temperature zone downstream of the multi-temperature zone tube furnace, the less the mass of NaCl in the mixture of tungsten oxide powder and NaCl.

[0014] The further improvement of the technical scheme of the present application is that the amount of argon gas introduced into the multi-temperature zone tube furnace is 20-400 sccm, and the pressure in the multi-temperature zone tube furnace is controlled to be less than 1 standard atmosphere by adjusting an external pressure valve.

[0015] Due to the adoption of the above technical scheme, the present application has the following technical effects:

[0016] The present application can realize the preparation of single-layer MoS2 / WS2 two-component gradient materials with controllable size by adjusting the amount of molten salt and the reaction temperature of the high-temperature zone, and by using the spatial anchoring limited growth method. The single-layer MoS2 / WS2 two-component gradient materials with a size of 5-80 mu m can be prepared. The large size can be used for the research of electronics and optoelectronics. The small size can be used for the research in the fields of electrocatalysis, photoelectrocatalysis, photocatalysis and biosensing due to the increase of heterojunction density and grain boundary density caused by the reduction of crystal grain size.

[0017] The present application adopts the corundum boat with a slightly concave bottom surface, so that a narrow gap can be left between the deposition substrate and the bottom surface, thereby avoiding the direct contact between the deposition substrate and the relatively low-melting-point substances remaining in the bottom of the corundum boat after multiple reactions, and thus a relatively clean heterojunction sample can be formed. Meanwhile, the narrow gap can also promote the limited growth of the reaction products.

[0018] The present application utilizes the difference in melting points of WO3 and MoO3, and controls the temperature of the precursor to make it sequentially deposited on the substrate in the form of gas-liquid-solid. The sample deposited first anchors the nucleation points, and then the subsequent samples undergo epitaxial growth as the temperature rises, thereby forming a two-component heterojunction sample. By controlling the temperature, the energy for promoting nucleation and growth is given to the sample, and thus the growth with controllable size is realized, and samples with different sizes and controllable size are prepared. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a mechanism diagram of the spatial anchoring limited growth method of the present application;

[0020] Figure 2is an optical photo of the 50-80 μm size continuous single-layer MoS2 / WS2 bi-component gradient material prepared in Example 1 of the present application;

[0021] Figure 3 is a fluorescent photo of the 50-80 μm size continuous single-layer MoS2 / WS2 bi-component gradient material prepared in Example 1 of the present application;

[0022] Figure 4 is an optical photo of the 20-30 μm size stitch-grown single-layer MoS2 / WS2 bi-component gradient material prepared in Example 2 of the present application;

[0023] Figure 5 is a fluorescent photo of the 20-30 μm size stitch-grown single-layer MoS2 / WS2 bi-component gradient material prepared in Example 2 of the present application;

[0024] Figure 6 is an optical photo of the 5-10 μm size or less single-layer MoS2 / WS2 bi-component gradient material prepared in Example 3 of the present application;

[0025] Figure 7 is a fluorescent photo of the 5-10 μm size or less single-layer MoS2 / WS2 bi-component gradient material prepared in Example 3 of the present application;

[0026] Figure 8 is Figure 4 Raman line-scan data of the single-layer MoS2 / WS2 bi-component gradient material in Example 1;

[0027] Figure 9 is Figure 4 PL line-scan data of the single-layer MoS2 / WS2 bi-component gradient material in Example 1;

[0028] Figure 10 is a low-magnification photo of the sample prepared in Example 3 taken by a scanning electron microscope;

[0029] Figure 11 is a cross-sectional schematic diagram of the flat-bottomed corundum boat in Comparative Example 1;

[0030] Figure 12 is a cross-sectional schematic diagram of the micro-concave-bottomed corundum boat used in Example 1;

[0031] Figure 13 is an optical photo of the sample prepared in Comparative Example 1;

[0032] Figure 14 is an optical photo of the sample prepared in Comparative Example 2;

[0033] Figure 15 is an optical photo of the sample prepared in Comparative Example 3;

[0034] Figure 16 This is an optical photograph of the sample prepared in Comparative Example 4. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0036] This invention discloses a one-step method for preparing monolayer MoS2 / WS2 bicomponent gradient materials, such as... Figure 1 The diagram shown is a schematic representation of the mechanism of the horizontal spatial anchoring confined growth method used in this invention.

[0037] A one-step method for preparing monolayer MoS2 / WS2 bicomponent gradient materials includes the following steps:

[0038] 1. Clean the SiO2 / Si substrate with acetone and ethanol using ultrasonic cleaning, and dry it with N2 as the substrate for deposition;

[0039] 2. Argon gas is used to clean the quartz tube and corundum boat of the multi-temperature zone tube furnace;

[0040] 3. Place 0.5–2.0 g of sulfur powder on one side of a corundum boat with a length of 3–6 cm, and compact the sulfur powder with a spatula. Seal the corundum boat containing the sulfur powder with aluminum foil. Use a fine steel needle to poke two to three small holes with a diameter of 0.5 mm on one side of the sulfur powder. Then place the corundum boat containing the sulfur powder in the upstream low-temperature zone of the multi-temperature zone tubular furnace. Separately place 0.5–1.5 g of tungsten oxide mixed with a small amount of sodium chloride powder and 0.1–0.5 g of molybdenum oxide powder in the upstream of the long corundum boat in the downstream high-temperature zone of the multi-temperature zone tubular furnace. Place the deposited substrate in the long corundum boat 4–7 cm downstream of the molybdenum oxide powder, with the deposited surface (silica surface) facing down. The long corundum boat is 15–25 cm long, 1.0–1.2 cm high, and 0.9–0.95 cm wide at the bottom, with the bottom recessed to form a gap between it and the inverted substrate.

[0041] 4. In step 3, the upstream low-temperature zone of the multi-temperature zone tube furnace is heated to 160-210℃, and the downstream high-temperature zone is heated to 750-960℃; the two corundum boats are both positioned 2cm away from the thermal resistance wire of the multi-temperature zone tube furnace, and are located downstream of the resistance wire.

[0042] 5. Maintain the argon flow rate in the multi-temperature zone tubular furnace at 20-400 sccm, and adjust the external pressure reducing valve to ensure the pressure inside the tube is less than 1 standard atmosphere.

[0043] 6. Control the heating time to reach the target temperature in step 4 to be 30~50min, and the holding time at the target temperature to be 20~50min; then let it cool naturally to room temperature to obtain a single-layer MoS2 / WS2 bicomponent gradient material.

[0044] Example 1

[0045] A one-step method for preparing monolayer MoS2 / WS2 bicomponent gradient materials includes the following steps:

[0046] 1. Clean the SiO2 / Si substrate with acetone and ethanol using ultrasonic cleaning, and then dry it with N2.

[0047] 2. Argon gas is used to clean the quartz tube and corundum boat of the multi-temperature zone tube furnace;

[0048] 3. Place 1.0g of sulfur powder on one side of a 5cm long corundum boat and compact the sulfur powder with a spatula. Seal the corundum boat containing the sulfur powder with aluminum foil. Use a fine steel needle to poke two small holes with a diameter of 0.5mm on one side of the sulfur powder. Then place the corundum boat containing the sulfur powder in the upstream low-temperature zone of a multi-temperature zone tubular furnace. Separately place 0.5g of tungsten oxide and 1mg of sodium chloride mixed powder and 0.2g of molybdenum oxide powder in the upstream of the long corundum boat in the downstream high-temperature zone of the multi-temperature zone tubular furnace. Place the deposited substrate in the long corundum boat 3cm downstream of the molybdenum oxide powder, with the deposited surface (silica surface) facing down. The long corundum boat is 15cm long, 1.2cm high, and 0.9cm wide at the bottom, with the bottom recessed to form a gap between it and the inverted substrate.

[0049] 4. In step 3, the upstream low-temperature zone of the multi-temperature zone tubular furnace is heated to 190℃, and the downstream high-temperature zone is heated to 750℃.

[0050] 5. Maintain the argon flow rate in the multi-temperature zone tubular furnace at 50 sccm, and stabilize the pressure inside the tube at 5 kPa by adjusting the external pressure reducing valve.

[0051] 6. Control the heating time to reach the target temperature in step 4 to 35 min, and the holding time at the target temperature to 30 min; then let it cool naturally to room temperature to obtain a single-layer MoS2 / WS2 bicomponent gradient material with a size of about 50~80μm.

[0052] Example 2

[0053] A one-step method for preparing monolayer MoS2 / WS2 bicomponent gradient materials includes the following steps:

[0054] 1. Clean the SiO2 / Si substrate with acetone and ethanol using ultrasonic cleaning, and then dry it with N2.

[0055] 2. Argon gas is used to clean the quartz tube and corundum boat of the multi-temperature zone tube furnace;

[0056] 3. Place 2.0g of sulfur powder on one side of a 4cm long corundum boat and compact the sulfur powder with a spatula. Seal the corundum boat containing the sulfur powder with aluminum foil. Use a fine steel needle to poke three small holes with a diameter of 0.5mm on one side of the sulfur powder. Then place the corundum boat containing the sulfur powder in the upstream low-temperature zone of a multi-temperature zone tubular furnace. Separately place 0.8g of tungsten oxide and 0.1mg of sodium chloride mixed powder and 0.35g of molybdenum oxide powder in the upstream of the long corundum boat in the downstream high-temperature zone of the multi-temperature zone tubular furnace. Place the deposited substrate in the long corundum boat 5cm downstream of the molybdenum oxide powder, with the deposited surface (silica surface) facing down. The long corundum boat is 20cm long, 1.1cm high, and 0.95cm wide at the bottom, with the bottom recessed to form a gap between it and the inverted substrate.

[0057] 4. In step 3, the upstream low-temperature zone of the multi-temperature zone tubular furnace is heated to 200℃, and the downstream high-temperature zone is heated to 830℃.

[0058] 5. Maintain the argon flow rate in the multi-temperature zone tubular furnace at 100 sccm, and stabilize the pressure inside the tube at 12 kPa by adjusting the external pressure reducing valve.

[0059] 6. Control the heating time to reach the target temperature in step 4 to 35 minutes. Hold the target temperature for 35 minutes. Then allow it to cool naturally to room temperature to obtain a single-layer MoS2 / WS2 bicomponent gradient material with a size of approximately 20~30μm.

[0060] Example 3

[0061] A one-step method for preparing monolayer MoS2 / WS2 bicomponent gradient materials includes the following steps:

[0062] 1. Clean the SiO2 / Si substrate with acetone and ethanol using ultrasonic cleaning, and then dry it with N2.

[0063] 2. Argon gas is used to clean the quartz tube and corundum boat of the multi-temperature zone tube furnace;

[0064] 3. Place 1.8g of sulfur powder on one side of a 6cm long corundum boat and compact the sulfur powder with a spatula. Seal the corundum boat containing the sulfur powder with aluminum foil. Use a fine steel needle to poke three small holes with a diameter of 0.5mm on one side of the sulfur powder. Then place the corundum boat containing the sulfur powder in the upstream low-temperature zone of a multi-temperature zone tubular furnace. Separately place 1.3g of tungsten oxide and 0.06mg of sodium chloride mixed powder and 0.5g of molybdenum oxide powder in the upstream of the long corundum boat in the downstream high-temperature zone of the multi-temperature zone tubular furnace. Place the deposited substrate in the long corundum boat 6cm downstream of the molybdenum oxide powder, with the deposited surface (silica surface) facing down. The long corundum boat is 25cm long, 1.2cm high, and 0.9cm wide at the bottom, with the bottom recessed to form a gap between it and the inverted substrate.

[0065] 4. In step 3, the upstream low-temperature zone of the multi-temperature zone tubular furnace is heated to 180℃, and the downstream high-temperature zone is heated to 950℃.

[0066] 5. Maintain the argon flow rate in the multi-temperature zone tubular furnace at 220 sccm and the pressure inside the tube at a stable 55 kPa.

[0067] 6. Control the heating time to reach the target temperature in step 4 to 35 minutes. Hold the target temperature for 35 minutes. Then allow it to cool naturally to room temperature to obtain a single-layer MoS2 / WS2 bicomponent gradient material with a size of approximately 5~10 μm.

[0068] Compare with Example 1

[0069] The difference from Embodiment 1 is that the bottom surface of the long corundum boat is a plane.

[0070] Comparative Example 1 uses a corundum boat with a flat bottom, unlike the corundum boat with a slightly concave bottom mentioned in Example 1. The differences are shown in the appendix. Figure 11 , Figure 12 Schematic diagrams of different corundum boat cross sections. Figure 13 An optical photograph of a sample prepared using a corundum boat with a flat bottom. (Comparison) Figure 13 and Figure 2 , Figure 4 , Figure 6 As can be seen from the optical photographs of the samples prepared in the examples, the corundum boat samples with flat bottom surfaces have uneven growth sizes and a lot of particulate matter adsorbed at the sample edges. Such samples are not convenient for subsequent structural and performance characterization and have low research value.

[0071] Compare with Example 2

[0072] The difference from Example 1 is that NaCl is not added in this example, but all other operations are the same.

[0073] like Figure 14 As shown, under the same conditions as in Example 1, no sample nucleation occurred on the SiO2 / Si surface when NaCl was not added.

[0074] Compare with Example 3

[0075] The difference from Example 2 is that the amount of NaCl used is 5 mg. The higher amount of NaCl results in the following preparation method: Figure 15 The sample shown does not exhibit crystal self-forming properties.

[0076] Compare with Example 4

[0077] The difference from Example 3 is that the amount of NaCl used is 0.5 mg. The experimentally prepared product is also as described. Figure 16The sample shown is amorphous and lacks self-forming properties.

[0078] The monolayer MoS2 / WS2 bicomponent gradient material samples of different sizes obtained by the method steps of this invention were characterized by optical microscopy, fluorescence microscopy, scanning electron microscopy, Raman spectroscopy, and other equipment, and the results were as follows: Figures 2-11 The accompanying figures confirm that the synthesized samples are monolayer MoS2 / WS2 bicomponent gradient materials of different sizes. The obtained samples have good crystallinity and purity, including both large-sized samples of nearly 100 micrometers and relatively dense small-sized samples, which have great application prospects in fields such as photodetectors, flexible devices, and energy.

[0079] Figure 2 An optical photograph of the large-size monolayer MoS2 / WS2 bicomponent gradient material prepared in Example 1 shows that the prepared sample not only has a large individual grain size, but also exhibits the characteristics of stitch growth. The grain boundaries brought about by stitch growth can provide convenience for subsequent research on the grain boundary characteristics of heterostructures. Figure 3 for Figure 2 The fluorescence images of the samples shown reveal enhanced fluorescence in the transition region of a single sample. This phenomenon is related to the appropriate width of the transition region and the presence of a small number of defect states. An appropriate transition region width allows the built-in electric field of the gradient material to exert a greater effect, thereby promoting charge separation, reducing nonradiative recombination, and increasing the quantum yield of the transition region. Similarly, a small number of defects can also promote rapid charge separation, resulting in enhanced fluorescence in the transition region. These samples provide a convenient basis for studying the influence of the built-in electric field of heterojunctions on exciton fluorescence lifetime, quantum yield, valley polarization, etc., and can promote in-depth research on the unique electronic structure of monolayer horizontal heterojunctions.

[0080] Figure 4 The optical photographs of the samples prepared in Example 2 show that the size of a single sample is about 20~30μm, and it also exhibits a suture growth state.

[0081] Figure 5 for Figure 4 The fluorescence images of the corresponding samples show that fluorescence enhancement also occurs in the transition region of the samples.

[0082] Figure 6 An optical photograph of the sample prepared in Example 3 shows that the size of a single sample is about 5~10 μm.

[0083] Figure 7 for Figure 6 The fluorescence images of the corresponding samples also show an enhanced fluorescence phenomenon in the transition region.

[0084] Figure 8for Figure 4 Raman line scan data of the sample shows that the transition from WS2 to MoS2 is gradual from the edge to the center of the sample.

[0085] Figure 9 for Figure 4 The PL line scan data of the sample also show that the PL peak position gradually shifts from high to low from the edge to the center of the sample, which corresponds to the characteristics of the PL spectrum of WS2 and MoS2.

[0086] Figure 10 The low-magnification photograph of the sample prepared in Example 3, taken with a scanning electron microscope, shows that its nucleation density is extremely high.

[0087] Figure 11 This is a schematic cross-sectional view of the corundum boat with a flat bottom surface in Comparative Example 1, with a small gap between the substrate and the corundum boat.

[0088] Figure 12 This is a schematic cross-sectional view of the corundum boat with a slightly concave bottom surface used in Example 1. Due to the concavity at the bottom, the gap between the substrate and the corundum boat is relatively large.

[0089] Figure 13 This is an optical photograph of the sample with uneven size and unclean surface prepared in Comparative Example 1.

[0090] Figure 14 The image shows an optical photograph of the sample prepared in Comparative Example 2. The sample grows randomly and chaotically, without crystal self-forming properties.

[0091] Figure 15 The image shows an optical photograph of the sample prepared in Comparative Example 3. The prepared sample is thicker and also lacks crystal self-forming properties.

[0092] Figure 16 The image shows an optical photograph of the sample prepared in Comparative Example 4, which shows that virtually no crystals are nucleated on the substrate surface.

[0093] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, principle, etc. of the present invention should be covered within the scope of protection of the present invention.

[0094] The specification of this invention lists various optional materials for the components; however, those skilled in the art should understand that the list of components is neither limiting nor exhaustive, and various components can be replaced by other equivalent materials not mentioned in this specification while still achieving the purpose of this invention. The specific embodiments mentioned in the specification are merely illustrative and not intended to limit the scope of the invention.

[0095] Furthermore, the dosage range of each component in this invention includes any combination of any lower and upper limits mentioned in the specification, as well as any range formed by combining the specific content of the component in each specific embodiment as an upper or lower limit. All these ranges are covered within the scope of this invention; however, for the sake of brevity, these combined ranges are not listed one by one in the specification. Each feature of this invention listed in the specification can be combined with any other feature of this invention, and such combinations are also within the scope of disclosure of this invention; however, for the sake of brevity, these combined ranges are not listed one by one in the specification.

Claims

1. A method for preparing a one-step monolayer MoS2 / WS2 bicomponent gradient material, characterized in that: Sulfur powder was compacted on one side of the corundum boat using a spatula, and the corundum boat containing the sulfur powder was sealed and wrapped with aluminum foil. Two to three small holes with a diameter of 0.5 mm were punched on one side of the sulfur powder using a fine steel needle. The corundum boat containing the sulfur powder was then placed in the upstream low-temperature zone of a multi-zone tubular furnace. Tungsten oxide powder and NaCl mixture and molybdenum oxide powder were placed sequentially in the upstream of the long corundum boat, and the deposited substrate was placed in the downstream of the long corundum boat, with the bottom of the long corundum boat concave downwards. The long corundum boat was then placed in the downstream high-temperature zone of the multi-zone tubular furnace. By adjusting the temperature of the downstream high-temperature zone of the multi-zone tubular furnace and the amount of NaCl mixed with tungsten oxide powder, monolayer MoS2 / WS2 bicomponent gradient materials of different sizes were prepared. The sulfur powder has a mass of 0.5–2.0 g, the tungsten oxide powder has a mass of 0.5–1.5 g, and the molybdenum oxide has a mass of 0.1–0.5 g. The size of the monolayer MoS2 / WS2 bicomponent gradient material is determined by the temperature of the downstream high-temperature zone of the multi-zone tubular furnace and the amount of NaCl used. When the temperature of the downstream high-temperature zone of the multi-zone tubular furnace is greater than or equal to 750℃ and less than 800℃, and the amount of NaCl used is 1-3 mg, the size of the prepared monolayer MoS2 / WS2 bicomponent gradient material is 50-80 μm. When the temperature of the downstream high-temperature zone of the multi-zone tubular furnace is greater than or equal to 800℃ and less than 890℃, and the amount of NaCl used is 0.1-0.2 mg, the size of the prepared monolayer MoS2 / WS2 bicomponent gradient material is... S2 The size of the bicomponent gradient material is 20-30 μm; when the temperature of the downstream high-temperature zone of the multi-temperature zone tube furnace is greater than or equal to 890℃ and less than or equal to 960℃ and the amount of NaCl is less than 0.1 mg, the size of the prepared layered MoS2 / WS2 bicomponent gradient material is 5-10 μm. The higher the temperature in the downstream high-temperature zone of the multi-temperature zone tubular furnace, the less NaCl is in the mixture of tungsten oxide powder and NaCl.

2. The method for preparing a one-step monolayer MoS2 / WS2 bicomponent gradient material according to claim 1, characterized in that: Both corundum boats are positioned 2cm off the multi-temperature zone tubular furnace thermal resistance wire, located downstream of the resistance wire.

3. The method for preparing a one-step monolayer MoS2 / WS2 bicomponent gradient material according to claim 1, characterized in that: The corundum boat containing sulfur powder is 3-6 cm long; the long corundum boat is 15-25 cm long and 1.0-1.2 cm high.

4. The method for preparing a one-step monolayer MoS2 / WS2 bicomponent gradient material according to claim 1, characterized in that: The deposited substrate is placed 4-7 cm away from the molybdenum oxide powder, with the silica side facing down; the bottom width of the long corundum boat is 0.9-0.95 cm.

5. The method for preparing a one-step monolayer MoS2 / WS2 bicomponent gradient material according to claim 1, characterized in that: The temperature control range of the upstream low-temperature zone of the multi-temperature zone tubular furnace is 160–210℃.

6. The method for preparing a one-step monolayer MoS2 / WS2 bicomponent gradient material according to claim 1, characterized in that: The argon gas flow rate in the multi-zone tubular furnace is between 20 and 400 sccm, and the internal pressure of the multi-zone tubular furnace is controlled to be less than 1 standard atmosphere by adjusting the external pressure valve.

Images