MoSe2 / SnSe2 composite nanosheet, and preparation method and application thereof

Abstract

The application provides a MoSe2 / SnSe2 composite nanosheet and a preparation method and application thereof. The MoSe2 / SnSe2 composite nanosheet is successfully synthesized at a relatively low reaction temperature for a short time, and compared with a heterostructure which needs to be reacted at above 900 DEG C for 80 hours by gas phase deposition, the synthesis of the nanocomposite heterostructure needs a low reaction temperature, a short reaction time, and is easy and simple to operate. In addition, the MoSe2 / SnSe2 composite nanosheet prepared by the application is in the form of a hexagonal flake coated with scales, and has a band gap of 0.88 eV. It is tested that an infrared photoelectric device comprising the MoSe2 / SnSe2 composite nanosheet has good photoelectric response performance.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor materials, specifically relating to a MoSe2 / SnSe2 composite nanosheet, its preparation method, and its application. Background Technology

[0002] Transition metal dichalcogenides (TMDCs) have widespread technical applications in optoelectronic devices such as photovoltaic cells, photodetectors, and field-effect transistors. The heterostructure of TDCs can easily achieve strong built-in fields, promote the separation of photogenerated carriers, and suppress dark current noise, thereby achieving high detection rates and high response speeds.

[0003] Studies have reported that SnSe2 has an indirect band gap of approximately 0.9 eV, and SnSe2 crystals have a band gap of 8.6 cm⁻¹ at room temperature. 2 ·V -1 ·s -1 MoSe2's high carrier mobility, exceeding that of many other reported two-dimensional materials, makes it a promising candidate for use in wide-range photodetectors. Furthermore, MoSe2 is a typical transition metal dichalcogenide (TMDC) compound with a direct bandgap of approximately 1.5 eV, holding potential value in broadband photodetection.

[0004] Currently, most studies on TMDC heterostructures are conducted through gas-phase reaction transfer processes. Gas-phase reactions, such as chemical vapor deposition (CVD), have been used for the scalable synthesis of high-quality, atomically thin van der Waals heterostructures. However, the high reaction temperatures and difficult-to-control reaction kinetics required for gas-phase reactions limit the synthesis of TMDC heterostructures. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a MoSe2 / SnSe2 composite nanosheet, its preparation method, and its application. This preparation method can achieve the preparation of high-quality MoSe2 / SnSe2 composite nanosheets, effectively reducing the synthesis temperature and time, while also lowering the difficulty of operating conditions and the preparation cost.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing MoSe2 / SnSe2 composite nanosheets, comprising the following steps:

[0008] S1: Mix the tin source, selenium source, and solvent to obtain solution A; mix the molybdenum source, selenium source, and solvent to obtain solution B;

[0009] The tin source is selected from tetraphenyltin;

[0010] S2: In a liquid-phase system containing a solvent, solution A is added to carry out the first reaction, and then solution B is added to carry out the second reaction to form MoSe2 / SnSe2 composite nanosheets.

[0011] Preferably, the addition of the dissolving solution A is carried out at 260~300°C.

[0012] Preferably, the reaction time for the first reaction is 5 to 10 minutes.

[0013] Preferably, the selenium source is selected from dibenzyldiselelenide.

[0014] Preferably, the molybdenum source is selected from molybdenum acetylacetonate.

[0015] In this invention, the selection of the molybdenum source affects the morphology of the final product. Therefore, after screening, this invention preferably uses molybdenum acetylacetonate as the molybdenum source.

[0016] Preferably, the solvent is selected from one or more of oleylamine, oleic acid, or octadecene.

[0017] Preferably, the molar ratio of the tin source to the selenium source is 0.050:(0.050~0.010); and the volume ratio of the tin source to the solvent is 0.05 mmol:(1~3) mL.

[0018] Preferably, the molar ratio of the molybdenum source to the selenium source is 0.050:(0.050~0.075); and the volume ratio of the molybdenum source to the solvent is 0.05 mmol:(1~3) mL.

[0019] Preferably, the mixing of solution A and solution B in step S1 is carried out under ultrasonic conditions.

[0020] Preferably, the power of the ultrasound is 150~200 W and the duration is 5~10 min.

[0021] Preferably, after the mixing of solution A and solution B is completed in step S1, the system is further heated to 110~150°C and kept at that temperature for 15~40 min under a protective gas condition.

[0022] Preferably, the first and second reactions are carried out under a protective atmosphere.

[0023] Preferably, the temperature of the second reaction is 260~300℃ and the time is 5~35 min.

[0024] Preferably, after the second reaction is completed, the process further includes cooling, washing, and drying.

[0025] Secondly, the present invention provides a MoSe2 / SnSe2 composite nanosheet prepared by the above preparation method, wherein the composite nanosheet has a hexagonal morphology and the surface of the hexagonal sheet is covered with scale-like flakes.

[0026] Preferably, the diameter of the hexagonal sheet is 400~700 nm.

[0027] Thirdly, the present invention also provides an infrared photodetector device comprising MoSe2 / SnSe2 composite nanosheets prepared by the above-described preparation method.

[0028] Preferably, the infrared photodetector further includes graphene, silicon wafer, metal electrodes, and circuit board.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] This invention successfully synthesized MoSe2 / SnSe2 composite nanosheets in a short time at a relatively low reaction temperature. Compared to heterostructures such as those prepared by vapor deposition, which require reactions above 900℃ for 80 hours, the synthesis of nanocomposite heterostructures requires a lower reaction temperature, shorter reaction time, and is more convenient and simple to perform. Furthermore, the MoSe2 / SnSe2 composite nanosheets obtained by this invention exhibit a hexagonal sheet-like morphology with scale-like coatings, differing from the sheet-like morphology of SnSe2 monomers and the flower-like morphology of MoSe2. Testing revealed that the band gap of the hexagonal composite nanosheets is 0.88 eV, different from the band gap of SnSe2 monomers (0.71 eV) and MoSe2 monomers (1.47 eV) prepared by the same method. This difference is attributed to the formation of the SnSe2 and MoSe2 composite nanosheets, which flattens the band gap and improves the conductivity of the nanostructure.

[0031] This invention utilizes a Keithley 2400 semiconductor performance analysis system to test a near-infrared optoelectronic device composed of MoSe2 / SnSe2 composite nanosheets, graphene, silicon wafers, metal electrodes, and a circuit board. The results show that the device has good photoelectric response performance, especially for light with a wavelength of 808 nm. Attached Figure Description

[0032] Figure 1 The image shows the SEM image of the MoSe2 / SnSe2 composite nanosheets obtained in Example 1.

[0033] Figure 2 The image shows a TEM image of the MoSe2 / SnSe2 composite nanosheets obtained in Example 1.

[0034] Figure 3The images shown are high-angle annular dark-field images (HAADF-STEM) of the MoSe2 / SnSe2 composite nanosheets obtained in Example 1, along with elemental mapping diagrams of Sn, Mo, and Se. Figure 3 Image a is a high-angle annular dark field image. Figure 3 b is the mapping graph of the Mo element. Figure 3 c is the mapping graph of Sn elements. Figure 3 d is the mapping graph of elements Se;

[0035] Figure 4 The images show the XRD patterns of the MoSe2 / SnSe2 composite nanosheets obtained in Example 1 and the SnSe2 and MoSe2 obtained in Comparative Examples 1 and 2.

[0036] Figure 5 XPS images of the MoSe2 / SnSe2 composite nanosheets obtained in Example 1; wherein, Figure 5 a is the total XPS spectrum of the MoSe2 / SnSe2 nanomaterials. Figure 5 b is the spectrum of Sn3d. Figure 5 c is the spectrum of Mo3d. Figure 5 d is the spectrum of Se3d.

[0037] Figure 6 The image shows the characteristic absorption spectrum of the MoSe2 / SnSe2 composite nanosheets obtained in Example 1 and the band gap obtained by fitting the characteristic absorption spectrum.

[0038] in, Figure 6 a is the characteristic absorption spectrum of the MoSe2 / SnSe2 composite nanosheets obtained in Example 1; Figure 6 b is the bandgap diagram obtained by fitting the characteristic absorption spectrum;

[0039] Figure 7 An optical photograph of the photodetector device prepared for performance testing according to Embodiment 1 of the present invention;

[0040] Figure 8 The MoSe2 / SnSe2 composite nanosheet photodetector prepared in Example 1 of this invention under the same light intensity but different wavelengths IV curve;

[0041] Figure 9 The MoSe2 / SnSe2 composite nanosheet photodetector prepared in Example 1 of this invention under different intensities of 808nm wavelength light. IV curve;

[0042] Figure 10Transmission electron microscopy (TEM) images of MoSe2 / SnSe2 composite nanosheets with different MoSe2 / SnSe2 ratios obtained in Example 2;

[0043] in Figure 10 a~10d are TEM images of MoSe2:SnSe2=2:1, 1:1, 1:2, and 1:4 composite nanosheets, respectively;

[0044] Figure 11 X-ray diffraction (XRD) patterns of MoSe2 / SnSe2 composite nanosheets with different composite ratios obtained in Example 2;

[0045] Figure 12 Transmission electron microscopy (TEM) images of MoSe2 / SnSe2 composite nanosheets with different reaction times obtained in Example 3;

[0046] in, Figure 12 a is a TEM image taken after 5 minutes of reaction. Figure 12 b is a TEM image taken at a reaction time of 40 min;

[0047] Figure 13 The images show TEM images of the SnSe2 and MoSe2 monomer materials obtained in Comparative Examples 1 and 2; where, Figure 13 a is a TEM image of the monomeric SnSe2 nanosheets. Figure 13 b is a TEM image of the monomeric MoSe2 nanoflower;

[0048] Figure 14 The images show the characteristic absorption spectra of SnSe2 and MoSe2 obtained in Comparative Examples 1 and 2, and the band gap diagrams obtained by fitting these characteristic absorption spectra.

[0049] in, Figure 14 a is the characteristic absorption spectrum of SnSe2 obtained in Comparative Example 1. Figure 14 b is the bandgap diagram obtained by fitting the characteristic absorption spectrum of SnSe2. Figure 14 c is the characteristic absorption spectrum of MoSe2 obtained in Comparative Example 2. Figure 14 d is the bandgap diagram obtained by fitting the characteristic absorption spectrum of MoSe2;

[0050] Figure 15 The images show TEM images of the SnSe2 monomer materials and composites obtained in Comparative Examples 3, 4, 5, and 6; among them, Figure 15 a is a TEM image of SnSe2 nanoribbons obtained by reaction using crystalline tin tetrachloride as the tin source; Figure 15 b is a TEM image of SnSe2 cubes obtained by the reaction with tin dioxide as the tin source; Figure 15c is a TEM image of the complex formed by SnSe2 nanoribbons and MoSe2 obtained by the reaction with crystalline tin tetrachloride as the tin source; Figure 15 d is a TEM image of SnSe2 nanoribbons obtained by reacting tin dioxide as a tin source and combining them with MoSe2;

[0051] Figure 16 The images show the XRD patterns of the SnSe2 monomer materials obtained in Comparative Examples 3 and 4. Detailed Implementation

[0052] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0053] In existing technologies, most TMDC heterostructures are prepared using gas-phase reactions, which suffer from difficulties in control and high reaction temperatures. This invention provides a method for preparing MoSe2 / SnSe2 composite nanosheets, comprising the following steps:

[0054] S1: Mix the tin source, selenium source, and solvent to obtain solution A; mix the molybdenum source, selenium source, and solvent to obtain solution B;

[0055] S2: In a liquid-phase system containing a solvent, solution A is added to carry out the first reaction, and then solution B is added to carry out the second reaction to form MoSe2 / SnSe2 composite nanosheets.

[0056] In this invention, a tin source, a selenium source, and a solvent are first mixed to obtain solution A; then, a molybdenum source, a selenium source, and a solvent are mixed to obtain solution B. The order in which the steps to obtain solution A and solution B are obtained is not limited.

[0057] Through research, this invention has found that the choice of tin source affects the final MoSe2 / SnSe2 composite nanosheets. Therefore, this invention, after screening, preferably selects an organotin source, and more preferably tetraphenyltin, as the tin source.

[0058] In this invention, the selenium source is selected from dibenzyldiselelenide; the molybdenum source is preferably selected from organic molybdenum sources, more preferably molybdenum acetylacetonate; the solvent is selected from any one or more of oleylamine, oleic acid or octadecene, preferably oleylamine.

[0059] In some embodiments of the present invention, the tin source and selenium source are preferably mixed with the solvent at a molar ratio of 0.050:(0.050~0.010), preferably 0.050:(0.070~0.010); and the amount ratio of the tin source to the solvent is 0.05 mmol:(1~3) mL, preferably 0.05 mmol:(1~2) mL, to obtain solution A.

[0060] In some embodiments of the present invention, the molar ratio of the molybdenum source to the selenium source is preferably 0.050:(0.050~0.075), more preferably 0.050:(0.050~0.065); and the molar ratio of the molybdenum source to the solvent is 0.05 mmol:(1~3) mL, more preferably 0.05 mmol:(1~2) mL, to obtain solution B.

[0061] In some preferred embodiments of the present invention, the mixing of solution A and solution B in step S1 is carried out under ultrasonic conditions, specifically as follows:

[0062] Solvent A is obtained by ultrasonically mixing tin source, selenium source and solvent; solvent B is obtained by ultrasonically mixing molybdenum source, selenium source and solvent.

[0063] The preferred conditions for ultrasonic mixing are: power 150~200 W, more preferably 190 W; time 5~10 min, more preferably 5 min; in some embodiments of the present invention, the ultrasonic power is 190 W; and the ultrasonic time is 5 min.

[0064] In some specific embodiments of the present invention, the steps for obtaining dissolution A and solution B are preferably as follows:

[0065] Weigh 0.050 mmol (0.0214 g) tetraphenyltin, 0.10 mmol (0.0340 g) dibenzyldiselement and 1.0 mL oleylamine into a 10 mL centrifuge tube and sonicate them for 5 min to obtain solution A.

[0066] Weigh 0.050 mmol (0.0163 g) molybdenum acetylacetonate, 0.050 mmol (0.0170 g) dibenzyl diselenide and 1.0 mL oleylamine into a 10 mL centrifuge tube and sonicate them for 5 min to obtain solution B.

[0067] According to the present invention, after obtaining solution A and solution B, a liquid phase system containing solvent is provided.

[0068] In some embodiments of the present invention, preferably under protective gas conditions, the liquid-phase system containing the solvent is heated to 110-150°C and held at that temperature for 15-40 minutes to remove moisture and low-boiling-point impurities. In some embodiments of the present invention, the temperature is raised to 120°C and held for 30 minutes. The present invention does not impose any particular limitation on the type of protective gas; any conventional protective gas well known to those skilled in the art, such as nitrogen or argon, is acceptable.

[0069] In some specific preferred embodiments of the present invention, oleylamine is preferably added to a three-necked flask, and the system temperature is raised to 110~150℃ and held for 15~40 min under the stirring of a high-temperature magnetic stirrer and in a reaction atmosphere of high-purity protective gas, more preferably held at 120~140℃ for 20~30 min to remove moisture and low-boiling-point impurities. The rotational speed of the high-temperature magnetic stirrer is 300~500 rpm, more preferably 400 rpm.

[0070] Then, according to the present invention, a first reaction is carried out after adding solution A to a liquid-phase system containing a solvent. Preferably, solution A is added at a ratio of (5~10) mL: 0.05 mmol, more preferably 0.05 mmol: 5 mL. The addition of solution A is preferably carried out at 260~300°C, more preferably at 270~290°C, and even more preferably at 280°C. That is, it is preferable to heat the liquid-phase system containing the solvent to 260~300°C before adding solution A to carry out the first reaction. The reaction is preferably carried out at 260~300°C for 5~10 min.

[0071] After the first reaction is completed, according to the present invention, it is preferable to add solution B to carry out a second reaction to form MoSe2 / SnSe2 composite nanosheets. The addition of solution B is preferably carried out at a temperature of 260-300°C, more preferably 270-290°C. In some embodiments of the present invention, solution B is added at 280°C. The reaction time is preferably 5-35 min, more preferably 25 min, at which time MoSe2 / SnSe2 composite nanosheets can be obtained; the protective gas atmosphere is maintained until the reaction is completed, the mixture is cooled to room temperature, and then the product is removed.

[0072] It should be noted that the solution A and solution B are added by placing them into a syringe and injecting them into the liquid phase system.

[0073] In this invention, the order in which solution A and solution B are added to the liquid phase system is very important. If solution B is added first and then solution A is added, the morphology of the target MoSe2 / SnSe2 composite nanosheets cannot be obtained.

[0074] In some preferred embodiments of the present invention, after the above reaction is completed, the following post-processing is preferably performed: cooling, washing, and drying. The cooling is preferably performed by naturally cooling to room temperature under a protective gas atmosphere after the reaction has stopped. The product is centrifuged at 8000-10000 rpm for 2-5 min, the liquid is discarded, and the black precipitate is retained and washed repeatedly with anhydrous ethanol and / or n-hexane 2-3 times. After the above washing, the obtained black solid is dried. The drying is preferably vacuum drying; the drying temperature is preferably 30-60℃, and the drying time is 5-15 min to obtain MoSe2 / SnSe2 composite nanosheets. SEM characterization shows that the obtained MoSe2 / SnSe2 composite nanosheets are hexagonal nanosheets with scaly flakes distributed on the surface of the hexagonal flakes. The diameter of the hexagonal flakes is 400-700 nm, preferably around 600 nm.

[0075] The preparation method provided by this invention is a solution-phase synthesis method. It uses tin source, molybdenum source and selenium source as precursors and carries out the reaction in a liquid-phase reaction medium. The MoSe2 / SnSe2 composite nanosheets are obtained through two-step thermal injection synthesis, which greatly reduces the reaction temperature and reaction time. The operation is simple, convenient and easy to implement, and easy to control.

[0076] Tests showed that the band gap of the MoSe2 / SnSe2 hexagonal composite nanosheets provided by this invention is 0.88 eV, which is different from the band gap of SnSe2 monomer (0.71 eV) and MoSe2 monomer (1.47 eV). The reason for the difference is that the formation of SnSe2 and MoSe2 composite nanosheets flattens the band gap and improves the conductivity of the nanostructure.

[0077] The present invention also provides an infrared photodetector device comprising the MoSe2 / SnSe2 composite nanosheets described above. Generally, the infrared photodetector device further includes graphene, a silicon wafer, metal electrodes, and a circuit board.

[0078] In some embodiments of the present invention, the infrared photodetector is composed of MoSe2 / SnSe2 composite nanosheets, graphene, a silicon wafer, a metal electrode, and a circuit board. The MoSe2 / SnSe2 composite nanosheets are in contact with the graphene and the silicon wafer, and the silicon wafer and graphene are respectively connected to the metal electrode; the metal electrode is connected to the circuit board.

[0079] To further illustrate the present invention, the following embodiments provide a detailed description. The experimental materials used in the following embodiments of the present invention are all commercially available products. Example 1

[0080] This embodiment provides a MoSe2 / SnSe2 composite nanosheet, the preparation method of which is as follows:

[0081] S1. Add 5 mL of oleylamine to a 100 mL three-necked flask. Under the stirring of a high-temperature magnetic stirrer and in a reaction atmosphere of high-purity argon, raise the temperature to 120℃ and hold for 30 min to remove moisture and low-boiling-point impurities.

[0082] S2. Weigh 0.050 mmol (0.0214 g) tetraphenyltin, 0.10 mmol (0.0340 g) dibenzyldiselement and 1.0 mL oleylamine into a 10 mL centrifuge tube and sonicate them for 5 min to obtain solution A.

[0083] S3. Weigh 0.050 mmol (0.0163 g) molybdenum acetylacetonate, 0.050 mmol (0.0170 g) dibenzyl diselenide and 1.0 mL oleylamine into a 10 mL centrifuge tube and sonicate them for 5 min at a power of 190 W to obtain solution B.

[0084] S4. Heat the mixture in the three-necked flask obtained in step S1 to 280℃. Under this condition, rapidly inject solution A obtained in step S2 into the three-necked flask. The reaction solution immediately turns black. After reacting for 5 min, rapidly inject solution B obtained in step S3 into the three-necked flask and react for another 25 min. After the reaction is complete, cool naturally to room temperature in a high-purity argon atmosphere, centrifuge, and then wash repeatedly with anhydrous ethanol and n-hexane. Finally, centrifuge and dry in a vacuum drying oven to obtain MoSe2 / SnSe2 composite nanosheets.

[0085] Figure 1 The image shows a scanning electron microscope (SEM) image of the MoSe2 / SnSe2 composite nanosheets obtained in Example 1. It can be seen that the nanosheets are hexagonal sheets with a diameter of about 600 nm, as shown by the yellow dashed line in the figure; there are scaly flakes distributed on the surface of the hexagonal sheets (such as the blue area).

[0086] Figure 2 The image shows a transmission electron microscope (TEM) image of the MoSe2 / SnSe2 composite nanosheets obtained in Example 1; it more clearly shows the hexagonal sheet structure with scaly flakes on the surface, forming a hazy outer layer.

[0087] Figure 3 The images shown are high-angle annular dark-field images (HAADF-STEM) of the MoSe2 / SnSe2 composite nanosheets obtained in Example 1, along with elemental mapping diagrams of Sn, Mo, and Se. Figure 3 Image a is a high-angle annular dark field image. Figure 3 b is the mapping graph of the Mo element. Figure 3 c is the mapping graph of Sn elements. Figure 3 d is the mapping diagram of the Se element; it can be seen that the Mo element is distributed on the outer layer of the hexagonal plate, along the scale texture; the Sn element is mainly distributed in the center of the hexagonal plate, showing a hexagonal distribution, and there is no distribution in the extended scale texture; the Se element is distributed throughout the entire morphological structure.

[0088] Figure 4 The X-ray diffraction (XRD) patterns of the MoSe2 / SnSe2 composite nanosheets obtained in Example 1 and the SnSe2 and MoSe2 obtained in subsequent Comparative Examples 1 and 2 are shown. It can be seen that the diffraction peaks at 14.2°, 28.9°, 30.9°, 39.8°, 44.1°, 47.6°, 49.6°, 52.5° and 60.3° correspond to the crystal planes (001), (002), (011), (012), (003), (110), (111), (103) and (004) of the SnSe2 standard card (JCPDS card, 01−089−2939). The diffraction peaks at 31.1°, 37.7°, and 55.8° correspond to the (100), (103), and (110) crystal planes on the MoSe2 standard card (JCPDS card, 01−087−2419). Due to the poor crystallinity of MoSe2, the diffraction peak intensities are much smaller than those of SnSe2, so the diffraction peaks of MoSe2 are not prominent in the diffraction pattern of the composite nanosheets.

[0089] Figure 5 The image shows the X-ray photoelectron spectroscopy (XPS) spectrum of the MoSe2 / SnSe2 composite nanosheets obtained in Example 1; wherein, Figure 5 a is the XPS total spectrum of the MoSe2 / SnSe2 composite nanosheets. Figure 5 b is the 3d spectrum of Sn, Sn 4+ 3D 5 / 2 and 3D 3 / 2 The signal peaks shifted from 485.8 eV and 494.3 eV to 486.4 eV and 494.8 eV. Figure 5 c is the 3d spectrum of Mo, and the 3d spectrum of Mo... 5 / 2 and 3D 3 / 2 The signal peaks shifted from the low-energy regions of 229.1 eV and 232.2 eV to 228.8 eV and 231.9 eV; this indicates that the Mo element located on the surface of the composite nanosheet gained electrons through the interface surface of the substrate SnSe2 nanosheet, which also means that a coupling interface was established between SnSe2 and MoSe2.

[0090] Figure 6The characteristic absorption spectrum of the MoSe2 / SnSe2 composite nanosheets obtained in Example 1 is shown below. Figure 6 a) and the bandgap diagram obtained by fitting the absorption spectrum ( Figure 6 (b) The band gap of the product in this embodiment is 0.88 eV.

[0091] Figure 7 An optical photograph of the photodetector device prepared for performance testing in Example 1.

[0092] Figure 8 The MoSe2 / SnSe2 composite nanosheet photodetector prepared in Example 1 under the same light intensity but different wavelengths IV Line graph; Figure 9 The MoSe2 / SnSe2 composite nanosheet photodetector prepared in Example 1 of this invention under different intensities of 808 nm wavelength light. IV Line graph.

[0093] Depend on Figures 8-9 It can be seen that, in addition to the broad spectral response, under a fixed light intensity, the photocurrent of the device increases with the increase of the incident light wavelength, reaching a maximum at a wavelength of 808 nm, and then begins to decrease. This indicates that the device has extremely strong selectivity for light at a wavelength of 808 nm. By changing the light intensity (from 5 W / cm²), 2 Up to 50 mW / cm 2 As can be seen, the photocurrent increases with the increase of light intensity. Example 2

[0094] Compared to Example 1, the amount of molybdenum acetylacetonate in solution B in step S3 was changed to 2 times, 0.5 times, and 0.25 times the original amount, respectively, to alter the amount of MoSe2 in the composite nanosheets, thereby changing the composite ratio of the two monomers in the composite nanosheets. Simultaneously, the amount of dibenzyldiselelenide in solution B was adjusted accordingly with the change in the amount of molybdenum acetylacetonate. The remaining steps and parameters remained consistent with Example 1.

[0095] Figure 10 The images shown are transmission electron microscopy (TEM) images of MoSe2 / SnSe2 composite nanosheets with different MoSe2 / SnSe2 ratios obtained in Example 2; where... Figure 10 a~10d represent the TEM images of MoSe2:SnSe2 composite nanosheets with ratios of 2:1, 1:1, 1:2, and 1:4, respectively. High-quality MoSe2 / SnSe2 composite nanosheets can be obtained within this composite range. As the amount of composite MoSe2 decreases, the hazy outer layer formed by MoSe2 scaly nanosheets on the surface of the composite decreases accordingly.

[0096] Figure 11The X-ray diffraction (XRD) patterns of MoSe2 / SnSe2 composite nanosheets with different composite ratios obtained in Example 2 are shown. It can be seen that as the amount of MoSe2 composite increases, the XRD diffraction peaks are closer to those of the monomer MoSe2. Example 3

[0097] Compared to Example 1, the second reaction time after injecting solution B in S4 was adjusted to 5 min and 40 min, respectively. The remaining parameters and steps remained the same as in Example 1.

[0098] Figure 12 The images shown are transmission electron microscopy (TEM) images of MoSe2 / SnSe2 composite nanosheets obtained in Example 3 with different reaction times; Figure 12 a is a TEM image taken after 5 minutes of reaction. The morphology of the composite nanosheets has been basically formed, but SnSe2 nanosheets can still be observed. Figure 12 b is a TEM image taken when the reaction time is increased to 40 min after the injection of solution B, showing that the composite nanosheets break down.

[0099] Comparative Example 1

[0100] This comparative example provides a monomeric SnSe2 material, the preparation method of which is as follows:

[0101] S1. Add 5 mL of oleylamine to a 100 mL three-necked flask. Under the stirring of a high-temperature magnetic stirrer and in a reaction atmosphere of high-purity argon, raise the temperature to 120℃ and hold for 30 min to remove moisture and low-boiling-point impurities.

[0102] S2. Weigh 0.050 mmol (0.0214 g) tetraphenyltin, 0.10 mmol (0.0340 g) dibenzyldiselement and 1.0 mL oleylamine into a 10 mL centrifuge tube and sonicate them for 5 min to obtain solution A.

[0103] S3. Heat the mixture in the three-necked flask obtained in step S1 to 280℃. Under this condition, rapidly inject the solution A obtained in step S2 into the three-necked flask. The reaction solution immediately turns black, and the reaction proceeds for 30 min. After the reaction is complete, allow it to cool naturally to room temperature in a high-purity argon atmosphere, centrifuge, and then wash repeatedly with anhydrous ethanol and n-hexane. Finally, centrifuge again and dry in a vacuum drying oven to obtain the monomer SnSe2 nanosheets.

[0104] Comparative Example 2

[0105] This comparative example provides a monomeric MoSe2 material, the preparation method of which is as follows:

[0106] Referring to Comparative Example 1, the difference is that step S2 is changed to: weighing 0.050 mmol (0.0163 g) molybdenum acetylacetonate, 0.050 mmol (0.0170 g) dibenzyl diselenide and 1.0 mL oleylamine into a 10 mL centrifuge tube and sonicating them at a power of 190 W for 5 min to obtain solution B; in step S3, solution B is injected when the reaction temperature is reached, and the remaining parameters and steps are consistent with Comparative Example 1.

[0107] Figure 13 These are TEM images of the SnSe2 and MoSe2 monomer materials obtained in Comparative Examples 1 and 2; where, Figure 13 a is a TEM image of the monomer SnSe2 hexagonal nanosheets, which have a diameter of approximately 500 nm and no scaly texture on the surface; Figure 13 b is a TEM image of the monomeric MoSe2 nanoflower, whose texture is similar to the scaly texture of the composite nanosheet.

[0108] Figure 14 The characteristic absorption spectra of SnSe2 and MoSe2 nanomaterials obtained in Comparative Examples 1 and 2 and the band gaps obtained by fitting these absorption spectra are shown. The band gaps of the products in Comparative Examples 1 and 2 are 0.71 eV and 1.47 eV, respectively.

[0109] Comparative Example 3

[0110] S1. Add 5 mL of oleylamine to a 100 mL three-necked flask. Under the stirring of a high-temperature magnetic stirrer and in a reaction atmosphere of high-purity argon, raise the temperature to 120℃ and hold for 30 min to remove moisture and low-boiling-point impurities.

[0111] S2. Weigh 0.01 mmol (0.0351 g) crystalline tin tetrachloride, 0.10 mmol (0.0340 g) dibenzyl diselenide and 1.0 mL oleylamine and place them in a 10 mL centrifuge tube for ultrasonic dissolution. The ultrasonic power is 190 W and the time is 5 min to obtain solution A.

[0112] S3. Heat the mixture in the three-necked flask obtained in step S1 to 280°C. Under this condition, rapidly inject the solution A obtained in step S2 into the three-necked flask. The reaction solution immediately turns black, and the reaction proceeds for 30 minutes. After the reaction is complete, allow it to cool naturally to room temperature in a high-purity argon atmosphere, centrifuge, and then wash repeatedly with anhydrous ethanol and n-hexane. Finally, centrifuge again and dry in a vacuum drying oven to obtain the monomer SnSe2 nanoribbons.

[0113] Comparative Example 4

[0114] Compared with Comparative Example 3, the only difference is that 0.01 mmol of crystalline tin tetrachloride in S2 is replaced with 0.01 mmol of tin dioxide (0.0111 g), while the other parameters and steps are the same as those in Comparative Example 3.

[0115] Comparative Example 5

[0116] Compared with Example 1, the only difference is that tetraphenyltin in S2 is replaced with crystalline tin tetrachloride, while the other parameters and steps are the same as in Example 1.

[0117] Comparative Example 6

[0118] Compared with Example 1, the only difference is that tetraphenyltin in S2 is replaced with tin dioxide, while the other parameters and steps are the same as in Example 1.

[0119] TEM images of the SnSe2 monomer materials and composites obtained in Comparative Examples 3, 4, 5, and 6 are shown below. Figure 15 As shown; where, Figure 15 a is a TEM image of SnSe2 nanoribbons obtained by reaction using crystalline tin tetrachloride as the tin source; Figure 15 b is a TEM image of SnSe2 cubes obtained by the reaction with tin dioxide as the tin source; Figure 15 c is a TEM image of the complex formed by SnSe2 nanoribbons and MoSe2 obtained by the reaction with crystalline tin tetrachloride as the tin source; Figure 15 Image d shows a TEM image of SnSe2 nanoribbons synthesized with MoSe2 using tin dioxide as the tin source. Figure 15 a, Figure 15 b、 Figure 13 A comparison revealed that neither the SnSe2 monomers synthesized using crystalline tin tetrachloride as the tin source nor those synthesized using tin dioxide as the tin source could form the same morphology as the hexagonal SnSe2 nanosheets synthesized using tetraphenyltin as the tin source; Figure 15 c and Figure 15 a, Figure 2 The comparison revealed that while SnSe2 nanoribbons obtained using crystalline tin tetrachloride as the tin source could be successfully composited with MoSe2 to obtain composites with morphologies different from those of SnSe2 nanoribbons, they could not achieve the same morphology as... Figure 2 High-quality hexagonal composite nanosheets were obtained; from Figure 15 d and Figure 15 b. By comparison, it was found that SnSe2 monomers obtained by using tin dioxide as a tin source could not recombine with MoSe2, and the morphology of SnSe2 monomers obtained by using this tin source was destroyed.

[0120] The XRD patterns of the SnSe2 monomer materials obtained in Comparative Examples 3 and 4 are shown below. Figure 16As shown. Under the same conditions, SnSe2 monomer can be obtained by using crystalline tin tetrachloride and tin dioxide as tin sources, but some tin dioxide in the latter does not react completely.

[0121] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing MoSe2 / SnSe2 composite nanosheets, characterized in that, The method comprises the following steps: S1: mixing a tin source, a selenium source and a solvent to obtain a dissolving solution A; mixing a molybdenum source, a selenium source and a solvent to obtain a dissolving solution B; The tin source is selected from tetraphenyl tin; the selenium source is selected from dibenzyl diselenide; the molybdenum source is selected from molybdenum acetylacetone; and the solvent is selected from oleylamine; S2: in a liquid phase system containing a solvent, after adding the dissolving solution A, a first reaction is carried out, and then the dissolving solution B is added to carry out a second reaction, thereby forming MoSe2 / SnSe2 composite nanosheets.

2. The production method according to claim 1, characterized by, The adding of the dissolving solution A is carried out at 260-300 DEG C; The first reaction is carried out for 5-10 min.

3. The production method according to claim 1 or 2, characterized by, The molar ratio of the tin source to the selenium source is 0.050:(0.050-0.010); and the dosage ratio of the tin source to the solvent is 0.05 mmol:(1-3) mL; The molar ratio of the molybdenum source to the selenium source is 0.050:(0.050-0.075); and the dosage ratio of the molybdenum source to the solvent is 0.05 mmol:(1-3) mL.

4. The method of claim 1, wherein, The mixing in the preparation of the dissolving solution A and the dissolving solution B in step S1 is carried out under ultrasonic conditions; The power of the ultrasonic is 150-200 W, and the time is 5-10 min; The liquid phase system is heated to 110-150 DEG C under a protective gas, and then the dissolving solution A is added after being kept for 15-40 min.

5. The preparation method according to claim 1, characterized in that, The first reaction and the second reaction are carried out under a protective atmosphere; The temperature of the second reaction is 260-300 DEG C, and the time is 25-35 min; After the second reaction, cooling, washing and drying are further included. 6.The MoSe 2 / SnSe 2 composite nanosheet prepared by the method of any one of claims 1-5, wherein, The composite nanosheets are in a hexagonal sheet shape; The surface of the hexagonal sheet is covered with a scale-like sheet.

7. The MoSe2 / SnSe2 composite nanoplatelets according to claim 6, wherein, The diameter of the hexagonal sheet is 400-700 nm.

8. An infrared light detecting device, characterized by, The MoSe2 / SnSe2 composite nanosheets are prepared by the preparation method in any one of claims 1-5.

9. The infrared light detecting device according to claim 8, wherein The infrared light detection device further comprises graphene, a silicon sheet, a metal electrode and a circuit board.

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