A method for preparing large-area wrinkled tungsten diselenide nanostructures

Abstract

This invention discloses a method for preparing large-area wrinkled tungsten diselenide nanostructures. Using chemical vapor deposition (CVD) and strategies based on substrate engineering and rapid cooling, large-area, high-quality, and highly uniform wrinkled tungsten diselenide nanostructures are grown. By adjusting the substrate, growth temperature, and confinement height, the wavelength and amplitude of the wrinkled tungsten diselenide nanostructures can be effectively controlled. This invention eliminates the need for catalysts during growth, avoiding the introduction of other impurity elements, and simplifies the preparation process. This method for synthesizing wrinkled tungsten diselenide nanostructures offers advantages such as high preparation efficiency and low cost, meeting the needs of large-scale industrial production and showing broad application prospects in photoelectric detection, sensors, and imaging technologies.

Description

Technical Field

[0001] This invention relates to the field of transition metal chalcogenides, and more specifically to a method for preparing large-area wrinkled tungsten diselenide nanostructures. Background Technology

[0002] Since the discovery of graphene in 2004, two-dimensional materials have attracted widespread attention from researchers due to their excellent physical and chemical properties. Among numerous two-dimensional materials, transition metal chalcogenides are considered the most promising due to their tunable band gap, high carrier mobility, and high stability. Tungsten diselenide, as a type of transition metal chalcogenide, exhibits a direct band gap in monolayers and an indirect band gap in bilayers and multiple layers. Theoretically, the room temperature mobility of monolayer tungsten diselenide is 705 cm⁻¹. 2 V -1 s -1 Two-dimensional materials with wrinkled structures have broad application prospects in the field of optoelectronics. Compared with planar materials, two-dimensional materials with wrinkled structures exhibit many novel physical properties. The wrinkled structure leads to distortion of the intrinsic lattice structure, and wrinkle engineering is also an effective tool for controlling electronic properties, such as carrier mobility and band structure, which can be effectively controlled through wrinkles. Two-dimensional materials can be obtained with wrinkled structures of different wavelengths and amplitudes through stretching, compression, etc., thereby realizing dynamic control of their mechanical, electrical, and optical properties. In addition, wrinkles greatly improve the flexibility of materials, including bending, twisting, and stretching. Flexible electronic products based on wrinkled structures have attracted much attention in applications such as wearable electronic devices, artificial skin, panel displays, touch devices, health monitoring, and environmental monitoring. In recent years, people have been committed to exploring effective methods for highly controllable wrinkled nanostructures of two-dimensional materials. Compared with random wrinkles, one-dimensional or two-dimensional wrinkled patterns can be fabricated by transferring two-dimensional materials onto substrates with ordered microstructures, but due to the complexity of the process and the instability of the transfer process, it cannot meet the requirements of large-scale and efficient fabrication in industry. Therefore, achieving controllable preparation of high-quality wrinkled two-dimensional materials and simplifying the process and reducing costs is of great significance for promoting their practical industrial application. Summary of the Invention

[0003] To address the technical challenges of high cost, complex fabrication processes, and unstable transfer during the preparation of wrinkled tungsten diselenide nanostructures in transition metal chalcogenides, this invention provides a method for preparing large-area wrinkled tungsten diselenide nanostructures. Using atmospheric pressure chemical vapor deposition (CVD) and employing strategies such as substrate engineering and rapid cooling, the controllable preparation of high-quality, highly uniform, large-area, and tunable-wavelength and amplitude-adjustable wrinkled tungsten diselenide two-dimensional nanostructures was successfully achieved. This fabrication process is relatively simple and offers advantages such as high controllability, good reproducibility, and low cost. The prepared wrinkled tungsten diselenide shows broad application prospects in photoelectric detection, sensors, and catalysts.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a large-area wrinkled tungsten diselenide nanostructure includes the following steps: S1. Using soda-lime glass as a substrate, place tungsten trioxide foil on top of it and push it into the center of the heating zone of the tube furnace. Following the direction of the airflow from upstream to downstream, place the quartz boat containing selenium powder at the upstream inlet of the tube furnace. S2. Open the gas flow valve, clean the reaction chamber, and then, under the condition of the introduction of hydrogen and argon mixed gas, program the temperature to the center temperature of the heating zone to 780℃~820℃ and hold it for 8 min~25 min. Place the quartz boat containing selenium powder at a distance of 20~25 cm from the heating center. S3. After the growth is complete, keep the hydrogen-argon mixed gas continuously flowing in, and let the tube furnace cool down naturally to 650℃~700℃. Then open the tube furnace and the temperature inside the furnace will drop rapidly to room temperature, thus obtaining the wrinkled tungsten diselenide nanostructure (wrinkled tungsten diselenide nanosheets or / and nanoribbons).

[0005] Furthermore, in S1, tungsten trioxide foil is obtained by placing metallic tungsten foil in the center of the heating zone of a tube furnace and heating it to 700℃~750℃, then oxidizing it in air.

[0006] Furthermore, the oxidation time is 20 min to 35 min, preferably 23 min to 25 min.

[0007] Furthermore, in S2, the surface of the soda-lime glass substrate does not require special treatment, and the distance between the tungsten trioxide foil and the glass substrate is 1.4 mm to 3.2 mm.

[0008] Furthermore, in S2, argon gas is used for cleaning, and the cleaning time is 20~40 minutes.

[0009] Furthermore, in S2, the temperature program has a heating time of 25-35 min and a heating rate of 25-30 ℃ / min.

[0010] Furthermore, in S2, the selenium powder is high-purity selenium powder with a purity of 99.9%, and the dosage is 250 mg to 300 mg.

[0011] Furthermore, in S2, the selenium powder is placed by pushing it in, and the selenium powder is pushed in when the tube furnace reaches a reaction time of 780℃~820℃.

[0012] Furthermore, the argon flow rate in the hydrogen-argon mixture is 90 sccm to 110 sccm, and the hydrogen flow rate is 9 sccm to 20 sccm.

[0013] Furthermore, in S3, the tube furnace is opened by fully opening the furnace lid, which causes the temperature to drop rapidly. Due to the different thermal expansion coefficients of tungsten diselenide and the soda-lime glass substrate, there is a large thermal mismatch rate. The tungsten diselenide nanostructure generates shrinkage strain, which promotes the formation of wrinkled tungsten diselenide nanosheets and / or nanoribbons.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses soda-lime glass as a substrate. By selecting soda-lime glass of different thicknesses, the controllable preparation of tungsten diselenide nanostructures with different wavelengths can be achieved. Compared with other substrates such as silicon, silicon dioxide, mica, and sapphire, it can not only provide conditions for the formation of the final folded product, but also greatly reduce the preparation cost by using soda-lime glass substrate, which is conducive to the large-scale preparation of materials.

[0015] (2) No catalyst is involved in the entire experimental process of this invention, and the surface of the soda-lime glass substrate does not require special treatment, which simplifies the experimental process and avoids the introduction of impurity elements.

[0016] (3) The present invention adopts atmospheric pressure chemical vapor deposition, which is different from mechanical exfoliation, hydrothermal, molecular beam epitaxy and other methods. It can realize high quality, high uniformity and large area wrinkled tungsten diselenide nanostructures. Furthermore, by controlling the growth temperature, it can achieve controllable preparation of wrinkled tungsten diselenide of different sizes.

[0017] (4) The present invention adopts the method of pushing selenium powder in the experiment, which avoids uneven nucleation on the substrate during the heating stage, and is conducive to the growth of highly uniform large-area wrinkled tungsten diselenide nanostructures. Attached Figure Description

[0018] Figure 1 Digital photograph of a large-area wrinkled tungsten diselenide nanosheet prepared by the atmospheric pressure chemical vapor deposition method corresponding to Example 1; Figure 2 The optical microscopy characterization results of the large-area wrinkled tungsten diselenide nanosheets prepared by the atmospheric pressure chemical vapor deposition method corresponding to Example 1 are shown below. Figure 3 The Raman spectral characterization results are for the large-area wrinkled tungsten diselenide nanosheets prepared by the atmospheric pressure chemical vapor deposition method corresponding to Example 1. Figure 4 The photoluminescence characterization results are for the large-area wrinkled tungsten diselenide nanosheets prepared by the atmospheric pressure chemical vapor deposition method corresponding to Example 1. Figure 5 The atomic force microscopy characterization results of the large-area wrinkled tungsten diselenide nanosheets prepared by the atmospheric pressure chemical vapor deposition method corresponding to Example 1 are shown. Figure 6The scanning electron microscope characterization results are for the large-area wrinkled tungsten diselenide nanosheets prepared by the atmospheric pressure chemical vapor deposition method corresponding to Example 1. Figure 7 X-ray photoelectron spectroscopy characterization results of large-area wrinkled tungsten diselenide nanosheets prepared by the atmospheric pressure chemical vapor deposition method corresponding to Example 1; Figure 8 The polarization second harmonic characterization results are for the large-area wrinkled tungsten diselenide nanosheets prepared by the atmospheric pressure chemical vapor deposition method corresponding to Example 1. Figure 9 The transmission electron microscope and selected area electron diffraction characterization results are for the large-area wrinkled tungsten diselenide nanosheets prepared by the atmospheric pressure chemical vapor deposition method corresponding to Example 1. Figure 10 The optical microscopy characterization results of the large-area wrinkled tungsten diselenide nanoribbons prepared by the atmospheric pressure chemical vapor deposition method corresponding to Example 2; Figure 11 The scanning electron microscope characterization results are for the large-area wrinkled tungsten diselenide nanoribbons prepared by the atmospheric pressure chemical vapor deposition method corresponding to Example 2; Figure 12 The atomic force microscopy characterization results of the large-area wrinkled tungsten diselenide nanoribbons prepared by the atmospheric pressure chemical vapor deposition method corresponding to Example 2; Figure 13 The optical microscopy characterization results of the large-area tungsten diselenide nanosheets prepared by the atmospheric pressure chemical vapor deposition method corresponding to Example 3 are shown. Figure 14 The atomic force microscopy and Kelvin probe microscopy characterization results are for the large-area tungsten diselenide nanosheets prepared by the atmospheric pressure chemical vapor deposition method corresponding to Example 3. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, but the present invention is not limited thereto. Example 1

[0020] Tungsten foil was placed in the center of the heating zone of a tube furnace. The program was set to increase the temperature to 720 °C at a rate of 24 °C / min and oxidize in air for 24 min. After the tube furnace cooled naturally to room temperature, the tungsten trioxide foil was removed and used as the tungsten source. A 2.5 cm × 4.5 cm, 0.7 mm thick soda-lime glass substrate was placed on a graphite sheet. Graphite sheets with a thickness of 3.3 mm were placed on both sides of the soda-lime glass substrate. The tungsten trioxide foil was cut into 3 cm × 5 cm pieces and placed on the graphite sheets on both sides of the soda-lime glass substrate, completely covering it and maintaining a distance of 2.6 mm from the substrate. The tungsten trioxide foil and the soda-lime glass substrate were then pushed together into the center of the heating zone of the tube furnace. 270 mg of selenium powder was placed at the front end of a quartz boat. Following the upstream-to-downstream airflow direction, the quartz boat was pushed into the upstream inlet area of ​​the tube furnace. Before heating, argon gas was introduced into the tube furnace to purge the reaction chamber for 35 minutes at a flow rate of 1000 sccm. Then, a hydrogen-argon mixture was introduced at a flow rate of 15 sccm and 120 sccm for 5 minutes. Once the gas environment inside the tube furnace was stable, the heating program was set, allowing the heating zone to reach 810 °C over 28 minutes. At this point, the selenium powder was further pushed into the furnace to a position 24 cm from the center of the heating zone using a magnetic control device. The growth time was 12 minutes. After growth, the furnace lid was opened and the furnace was allowed to cool rapidly to room temperature after the temperature naturally dropped to 700 °C. The argon and hydrogen gases were then turned off, and the tube furnace was opened to remove the soda-lime glass substrate.

[0021] Digital photographs of the large-area wrinkled tungsten diselenide nanostructures obtained in Example 1 are shown below. Figure 1 As shown. The wrinkled tungsten diselenide nanostructure was characterized by optical microscopy, Raman spectroscopy, photoluminescence spectroscopy, atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, polarization second harmonic generation, and transmission electron microscopy. The results are as follows. Figures 2-9 As shown in the optical microscope images, the double-layer and multi-layer tungsten diselenide exhibits larger wrinkles and wavelengths compared to the single-layer region, while the single-layer tungsten diselenide region is relatively flat. During rapid cooling, due to the difference in thermal expansion coefficients between tungsten diselenide and the soda-lime glass substrate, a large thermal mismatch rate occurs, leading to stress and deformation of the tungsten diselenide. Raman spectroscopy characterization results show that its characteristic peak E... 1 2g Located at 250 cm -1The results are consistent with previously reported data, indicating that the grown sample is a tungsten diselenide wrinkled nanosheet. Photoluminescence spectroscopy characterization results show that monolayer tungsten diselenide exhibits a direct bandgap, with the highest photoluminescence intensity, while the photoluminescence intensity of bilayer and multilayer tungsten diselenide is quenched. This confirms that the grown tungsten diselenide is a direct bandgap semiconductor in its monolayer and an indirect bandgap semiconductor in its multilayer. Atomic force microscopy characterization results show that the average amplitude of the wrinkles in the bilayer tungsten diselenide is 50.3 nm, and the average wavelength is 1.2 μm. Scanning electron microscopy characterization results show that the monolayer region of the grown tungsten diselenide is relatively flat, while the wrinkles in the bilayer region are uniformly distributed throughout the nanosheet. X-ray photoelectron spectroscopy characterization results show that the peak positions of the W 4f orbital and Se 3d orbital are the same as those reported in the literature, and the fitted curves show high agreement with their standard binding energy curves, further confirming the successful preparation of high-quality wrinkled tungsten diselenide nanosheets. Polarization second harmonic characterization results show that the strain introduced by the wrinkled structure leads to changes in the polarization second harmonic intensity. Transmission electron microscopy (TEM) characterization results showed that the grown wrinkled tungsten diselenide nanosheets had high crystallinity. Selected area electron diffraction (SED) images showed a dot-like hexagonal structure, indicating that the wrinkled tungsten diselenide nanosheets were single crystals. Example 2

[0022] Following the growth process of Example 1, without changing other experimental conditions, the confinement height between the tungsten trioxide foil and the soda-lime glass substrate was reduced to 2.0 mm, which allowed for the growth of wrinkled tungsten diselenide nanoribbons, enabling the controllable preparation of wrinkled tungsten diselenide with different morphologies. Figure 10 The nanoribbons were characterized by optical microscopy, which showed that the double-layered and multi-layered tungsten diselenide nanoribbons had uniformly distributed wrinkles. Figure 11 Scanning electron microscopy characterization of the double-layered tungsten diselenide nanoribbons shows that the amplitude and wavelength of the wrinkles increase with the number of layers, and the periodicity of the wrinkles is relatively uniform. Figure 12 Atomic force microscopy (AFM) characterization of the nanoribbons revealed that the average amplitude of the monolayer tungsten diselenide wrinkles was 12.2 nm, with an average wavelength of 0.3 μm; the average amplitude of the bilayer tungsten diselenide wrinkles was 50.2 nm, with an average wavelength of 1.4 μm; and the average amplitude of the multilayer tungsten diselenide wrinkles was 201.2 nm, with an average wavelength of 3.2 μm. These characterization results confirm the successful preparation of wrinkled tungsten diselenide nanoribbons. Example 3

[0023] Based on the growth process in Example 1, the tube furnace was not opened in advance after the growth was completed. The furnace lid was opened and the substrate was removed after the tube furnace cooled down to room temperature naturally. Large-area tungsten diselenide nanosheets were obtained, but no wrinkles appeared. Figure 13 The tungsten diselenide nanosheets were characterized by optical microscopy. The grown tungsten diselenide nanosheets have a hexagonal structure and a smooth and uniform surface. Figure 14Characterization of tungsten diselenide nanosheets by atomic force microscopy and Kelvin probe microscopy showed that the surface of tungsten diselenide nanosheets was smooth, with low roughness and uniform surface potential.

Claims

1. A method for preparing a large-area wrinkled tungsten diselenide nanostructure, characterized in that, Includes the following steps: S1. Using soda-lime glass as a substrate, tungsten trioxide foil is placed on top of it and pushed into the center of the heating zone of a tube furnace. Following the upstream to downstream airflow direction, a quartz boat containing selenium powder is placed at the upstream inlet of the tube furnace. The tungsten trioxide foil is obtained by placing metallic tungsten foil in the center of the heating zone of the tube furnace, heating it to 700℃~750℃, and oxidizing it in air. The surface of the soda-lime glass substrate does not require special treatment. The distance between the tungsten trioxide foil and the glass substrate is 1.4 mm~3.2 mm. S2. Open the gas flow valve, clean the reaction chamber, and then, under the condition of introducing a hydrogen-argon mixed gas, program the temperature to the center temperature of the heating zone to 780℃~820℃ and maintain it for 8 min~25 min. Place the quartz boat containing selenium powder 20~25 cm away from the heating center. The selenium powder is placed by pushing it in, and the time point for pushing the selenium powder in is when the tube furnace reaches the reaction time of 780℃~820℃. S3. After the growth is complete, keep the hydrogen-argon mixed gas continuously flowing in, and let the tube furnace cool down naturally to 650℃~700℃. Then open the tube furnace by fully opening the furnace lid and rapidly reducing the temperature inside the furnace to room temperature to obtain wrinkled tungsten diselenide nanosheets and / or nanoribbons, i.e., wrinkled tungsten diselenide nanostructures.

2. The method for preparing large-area wrinkled tungsten diselenide nanostructures according to claim 1, characterized in that, The oxidation time is 20 min to 35 min.

3. The method for preparing large-area wrinkled tungsten diselenide nanostructures according to claim 1, characterized in that, In S2, argon gas is used for cleaning, and the cleaning time is 20~40 minutes.

4. The method for preparing large-area wrinkled tungsten diselenide nanostructures according to claim 1, characterized in that, In S2, the temperature program has a heating time of 25~35 min and a heating rate of 25~30℃ / min.

5. The method for preparing large-area wrinkled tungsten diselenide nanostructures according to claim 1, characterized in that, In S2, the selenium powder is high-purity selenium powder with a purity of 99.9%, and the dosage is 250 mg to 300 mg.

6. The method for preparing large-area wrinkled tungsten diselenide nanostructures according to claim 1, characterized in that, The flow rate of argon in the hydrogen-argon mixture is 90 sccm~110 sccm, and the flow rate of hydrogen is 9 sccm~20 sccm.

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