Indium selenide nanosheet compound as well as preparation method and application thereof

Abstract

The invention belongs to the field of nano materials, and particularly relates to an indium selenide nanosheet compound as well as a preparation method and application thereof. The preparation method provided by the invention comprises the following steps: mixing indium selenide nanosheets and silver ions in a second solvent, so that silver nanoparticles grow on the surfaces of the indium selenide nanosheets; the second solvent is a polar solvent, the Hansen solubility parameter delta of the third solvent is greater than or equal to 18MPa < 1 / 2 >, and the mass ratio of the indium selenide nanosheets to the silver ions is (5-50): 1. And growing silver nano-silver particles on the surface of indium selenide by utilizing a spontaneous oxidation-reduction reaction of indium selenide and silver nitrate, so as to prepare the indium selenide nanosheet compound with the surface modified by the silver nano-silver particles. The silver nanoparticles have strong absorption, and the photoelectric response effect of the indium selenide nanosheet is remarkably improved by compounding the silver nanoparticles and the indium selenide nanosheet.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials, and in particular to an indium selenide nanosheet composite, its preparation method, and its applications. Background Technology

[0002] Two-dimensional materials have attracted widespread attention from scientists in recent years. Graphene, for example, possesses excellent electrical and thermal conductivity and ultra-high strength. However, intrinsic graphene lacks semiconductor properties due to its zero band gap, which limits its application in nanoelectronic devices. Scientists have been striving to find graphene-like semiconductor materials. Indium selenide (InSe) is a recently discovered new member of the graphene-like semiconductor material family, representing an ideal material between silicon and graphene. It can be made as thin as a few atoms, like graphene, but with a considerably large and tunable band gap and high electron mobility (over 1000 cm⁻¹). 2 V -1 s -1 However, indium selenide has relatively low absorbance, resulting in a weak photoelectric response. Therefore, improving the photoelectric response of indium selenide has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0003] In view of this, the present invention provides a method for preparing indium selenide nanosheet composites to improve the photoelectric response of indium selenide.

[0004] In a first aspect, the present invention provides a method for preparing an indium selenide nanosheet composite, comprising: mixing indium selenide nanosheets with silver ions in a second solvent to grow silver nanoparticles on the surface of the indium selenide nanosheets.

[0005] The second solvent is selected as a polar solvent, and the Hansen solubility parameter δ of the third solvent is ≥18 MPa. 1 / 2 ,

[0006] The mass ratio of the indium selenide nanosheets to the silver ions is (5-50):1.

[0007] The method provided by this invention utilizes the spontaneous redox reaction between indium selenide and silver nitrate to grow silver nanoparticles on the surface of indium selenide, thereby obtaining an indium selenide nanosheet composite modified with silver nanoparticles. Silver nanoparticles exhibit strong absorption; combining silver nanoparticles with indium selenide nanosheets significantly enhances the photoelectric response of indium selenide nanosheets. Furthermore, the optimized process provided by this invention does not use any other catalysts, reducing agents, or other auxiliary agents, enabling the one-step preparation of the indium selenide-silver nanoparticle composite structure. It also achieves uniform growth of silver nanoparticles on the surface of indium selenide nanosheets without introducing other impurities. This method holds promise for the large-scale preparation of high-quality indium selenide nanosheet-silver nanoparticle composite structures with controllable silver-to-indium selenide concentration ratios, ultimately facilitating industrial production and application.

[0008] In some embodiments, the silver ions are selected as soluble silver salts capable of providing silver ions in the second solvent; and / or

[0009] The second solvent is selected from at least one of water, N-methylpyrrolidone, and dimethyl sulfoxide.

[0010] In some embodiments, the step of mixing indium selenide nanosheets with silver ions in a second solvent includes:

[0011] Indium selenide nanosheets are dispersed in the second solvent to form an indium selenide nanosheet dispersion. An aqueous solution of silver nitrate is then added dropwise to the indium selenide nanosheet dispersion while stirring continuously using ultrasonic stirring, magnetic stirring, or mechanical stirring.

[0012] Indium selenide nanosheets are dispersed in the second solvent to form an indium selenide nanosheet dispersion. The indium selenide nanosheet dispersion is then added dropwise to an aqueous solution of silver nitrate while stirring, using ultrasonic stirring, magnetic stirring, or mechanical stirring.

[0013] In some embodiments, during the mixing process, the concentration of the indium selenide nanosheets in the second solvent is 0.01-100 mg / mL, or

[0014] In the mixing process, the concentration of the indium selenide nanosheets in the second solvent is 0.1-10 mg / mL.

[0015] In some embodiments, indium selenide nanosheets are mixed with silver nitrate in a second solvent, wherein the concentration of silver nitrate is 0.01-100 mg / mL, or

[0016] Indium selenide nanosheets are mixed with silver nitrate in a second solvent, wherein the concentration of silver nitrate is 0.1-10 mg / mL.

[0017] In some embodiments, the indium selenide nanosheets have an average thickness of 0.8-83 nm and an average lateral dimension of 0.1-50 μm; and / or

[0018] The step of mixing indium selenide nanosheets with silver ions in a second solvent includes: mixing indium selenide nanosheets with silver nitrate in a second solvent, wherein the mass ratio of indium selenide nanosheets to silver nitrate is (10-100):1.

[0019] In some embodiments, the preparation method of the indium selenide nanosheets includes the following steps:

[0020] (1) The indium selenide block is placed in the first solvent and sealed, and ultrasonicated at 100-600W for 1-96 hours to obtain ultrasonic liquid, or sheared in a homogenizer at a rate of 0.3k-25k rpm for 1s-72h to obtain homogenized liquid;

[0021] (2) The ultrasonic liquid or the homogenate is centrifuged at a low speed of 100-4000 rpm and the supernatant is collected; and the supernatant is centrifuged at a high speed of 1000-18000 rpm, the speed of the high speed centrifugation is at least 120% of the speed of the low speed centrifugation, and the precipitate is collected. The precipitate obtained is indium selenide nanosheets.

[0022] In some embodiments, the first solvent is N-methylpyrrolidone (NMP).

[0023] Secondly, the present invention also provides an indium selenide nanosheet composite prepared by the above preparation method.

[0024] Thirdly, the present invention also provides the application of the indium selenide nanosheet composite prepared by the above preparation method in ultrafast electronic devices, solar cells, and biomedical detection.

[0025] The indium selenide nanosheet composite prepared in this invention exhibits stronger light absorption in the visible light band compared to indium selenide nanosheets. When fabricated as a photoelectrochemical working electrode, it shows a significant increase in photocurrent under a bias voltage of -0.2-0.6V, and the photocurrent without an applied bias voltage is 5.5 times that of indium selenide. Therefore, it holds promise for applications in ultrafast electronic devices, solar cells, and biomedical detection. Attached Figure Description

[0026] Figure 1 The X-ray diffraction pattern of the indium selenide nanosheets prepared in Example 2.

[0027] Figure 2 The images are transmission electron microscope (TEM) images of indium selenide nanosheets. Image a is a TEM image of the product obtained by ultrasonic exfoliation in Example 1, and image b is a TEM image of the product obtained by homogenizer shearing in Example 2.

[0028] Figure 3 Transmission electron microscopy (TEM) images of indium selenide nanosheets and indium selenide nanosheet composites: a is a TEM image of indium selenide nanosheets prepared in Example 3; b is a TEM image of the composite prepared in Example 4 at a silver concentration of 0.1 mg / mL; c is a TEM image of the composite prepared in Example 4 at a silver concentration of 0.5 mg / mL; d is a TEM image of the composite prepared in Example 4 at a silver concentration of 0.02 mg / mL. In bf, the mass ratio of silver to indium selenide is 0.10:1.

[0029] Figure 4 The image shows a transmission electron microscope (TEM) image of the indium selenide nanosheets and silver nanoparticle composite prepared in Example 5. The mass ratios of indium selenide nanosheets to silver nitrate in the AD images are 80:1, 40:1, 20:1, and 10:1, respectively.

[0030] Figure 5 The absorption spectra are those of the complexes prepared with different silver-selenium ratios in Example 6.

[0031] Figure 6 In Example 7, the scanning electron microscope (SEM) images of indium selenide nanosheets before and after treatment with silver nitrate solution are shown. a is an SEM image of indium selenide nanosheets after tape peeling, and b is an SEM image of a composite material of silver nanoparticles grown on the surface of indium selenide nanosheets after treatment with silver nitrate solution.

[0032] Figure 7 This is a test schematic diagram of the photodetector prepared in Example 8.

[0033] Figure 8 The results of photocurrent detection of InSe and InSe-Ag at different light wavelengths in Example 8 are shown. a is the current of InSe and InSe-Ag in darkness and light, and b is the photocurrent of InSe and InSe-Ag under simulated sunlight.

[0034] Figure 9 XPS images of indium selenide nanosheets before and after silver nitrate treatment.

[0035] Figure 10 The image shows a transmission electron microscope (TEM) image of the composite prepared in Example 9.

[0036] Figure 11 The image shows a transmission electron microscope (TEM) image of the composite prepared in Example 10.

[0037] Figure 12 The image shows a transmission electron microscope (TEM) image of the composite prepared in Example 11. Detailed Implementation

[0038] The following are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the embodiments of the present invention, and these improvements and modifications are also considered to be within the protection scope of the embodiments of the present invention.

[0039] Preparation of indium selenide nanosheets

[0040] This invention provides a method for preparing indium selenide nanosheets, comprising the following steps:

[0041] (1) Disperse the indium selenide bulk into the first solvent and sonicate it for 1-96 hours at a power of 100-600W, or shear it in a homogenizer at a rate of 3-25k rpm for 1-600min to obtain a homogenate.

[0042] (2) Centrifuge the homogenate at a low speed of 100-4000 rpm and collect the supernatant; then centrifuge the supernatant at a high speed of 1000-18000 rpm and collect the precipitate. The precipitate obtained is indium selenide nanosheets.

[0043] The speed of high-speed centrifugation is at least 120% of that of low-speed centrifugation.

[0044] The first solvent includes one or more of isopropanol, water, anhydrous ethanol, methanol, hexanol, acetone, N,N-dimethylformamide and dimethyl sulfoxide, N-methylpyrrolidone, N-cyclohexyl-2-pyrrolidone, 3-dimethyl-2-imidazolone, tetrahydrofuran, and N,N-dimethylformamide.

[0045] In the above embodiments of this application, this application first discovered that the surface energy of the first solvent matches the surface energy of the two-dimensional layered indium selenide material, and there is a certain interaction between the two to balance the energy required to peel off the bulk indium selenide. By controlling the centrifugation speed, indium selenide nanosheets can be formed very easily at room temperature.

[0046] The first solvent is selected from one or more of anhydrous isopropanol, N-methylpyrrolidone (NMP), N-cyclohexyl-2-pyrrolidone (CHP), 3-dimethyl-2-imidazolium ketone (DMI), tetrahydrofuran (THF), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO), but is not limited thereto. In some embodiments, NMP is selected as the first solvent. Using NMP as the first solvent helps to achieve efficient stripping, and the product remains stable therein. Specifically, NMP has a surface energy similar to InSe and a Hansen solubility parameter close to that of InSe. This allows solvent molecules to fully contact the material surface, enhancing interactions and facilitating the disruption of interlayer forces in layered materials, thus achieving efficient exfoliation. Simultaneously, NMP's moderate polarity provides a degree of solvation capability, effectively dispersing and stabilizing the exfoliated nanosheets, preventing agglomeration or recombination. This results in a high-concentration, uniformly dispersed nanosheet solution, facilitating subsequent separation, purification, and application. Furthermore, NMP's moderate viscosity avoids both excessively high viscosity hindering solvent molecule penetration and diffusion between layers and excessively low viscosity leading to insufficient shear force and reduced exfoliation efficiency. It effectively transfers energy such as ultrasound, promoting the exfoliation of layered materials. Moreover, NMP is chemically stable under conventional exfoliation conditions, resisting decomposition or chemical reactions with other substances. This ensures the stability of the solvent itself during exfoliation, providing a stable environment for the preparation of InSe nanosheets.

[0047] In step (1), the concentration of indium selenide in the first solvent is 0.01-100 mg / mL. In some embodiments, the concentration of indium selenide in the first solvent is 0.1-20 mg / mL.

[0048] In step (1), the ultrasound method is either water bath ultrasound or probe ultrasound.

[0049] In a preferred embodiment of this application, the ultrasonic power can be 100-600W, for example, 200, 300, 320, 350, 380, 400, 450, 500, 550, or 600W. Optionally, the ultrasonic power can be 350-550W, 100-300W, or 100-180W. The homogenizer speed can be 0.3k-25k rpm, for example, 0.3k, 1k, 10k, 20k, or 25k rpm.

[0050] In a preferred embodiment of this application, the ultrasonication time can be 14-48h, 1-12h, or 24-72h. Preferably, the ultrasonication time is 1-12h. The shearing time using a homogenizer can be 1s, 1min, 10min, 1h, 12h, or 72h.

[0051] Optionally, the ultrasonic process is conducted under sealed conditions at a temperature not exceeding 20°C. This prevents the indium selenide from oxidizing and deteriorating due to excessively high temperatures and contact with outside air. Preferably, the ultrasonic process temperature is 0-10°C, for example, 0, 4, 5, 8, or 10°C. Optionally, the homogenizer shearing process is conducted at near room temperature, with the solution temperature controlled within 5°C of room temperature. Preferably, the temperature difference is 2°C. Excessively high temperatures will oxidize and deteriorate the product, while excessively low temperatures will cause condensation of water vapor in the air, which will also oxidize and deteriorate the product.

[0052] The rotational speed of high-speed centrifugation is greater than that of low-speed centrifugation. In some embodiments, the rotational speed of low-speed centrifugation in step (2) is 100-4000 rpm. For example, 100, 300, 600, 1000, 1500, 2000, or 3000 rpm. In some embodiments, the rotational speed of low-speed centrifugation is 1000-4000 rpm. The centrifugation time of low-speed centrifugation can be 1-30 min. For example, 3, 5, 10, 15, or 25 min, preferably 1-8 min.

[0053] In step (2), the high-speed centrifugation speed is 1000-18000 rpm, for example, 1000, 3000, 6000, 9000, 12000, 15000 or 18000 rpm. In some embodiments, the high-speed centrifugation speed is 5000-18000 rpm, and the high-speed centrifugation time is 1-60 min, for example, 1, 3, 5, 10, 30 or 60 min, and in some embodiments, 2-30 min is selected.

[0054] The process includes, after collecting the precipitate in step (2), redispersing the purified indium selenide nanosheets in the first solvent to obtain a dispersion of indium selenide nanosheets.

[0055] In this step, the first solvent is selected from one or more of isopropanol, water, anhydrous ethanol, methanol, ethanol, acetone, N,N-dimethylformamide, and dimethyl sulfoxide. Preferably, the first solvent is an alcohol solvent such as isopropanol, ethanol, or methanol. These solvents can effectively disperse indium selenide nanosheets, and they evaporate quickly upon being dropped onto the electrode, leaving no residue.

[0056] The thickness of the indium selenide nanosheets is 1-100 atomic layers, that is, they are composed of 1-100 stacked monolayer indium selenide sheets, corresponding to a thickness of 0.8-83 nm. Further optionally, the thickness of the indium selenide nanosheets is 5-10 atomic layers (4-8.3 nm), 6-15, or 7-20 atomic layers.

[0057] The lateral dimensions of indium selenide nanosheets are 0.8-50 μm, for example, 1, 2, 5, 10, 20, 30, 45, or 50 μm. Here, the lateral dimension refers to the length or width of the indium selenide nanosheet. Further, the lateral dimensions of the indium selenide nanosheets are 2-50 μm or 2-20 μm.

[0058] The present invention provides a method for preparing indium selenide nanosheets. Indium selenide bulk is dispersed in a first solvent, and indium selenide nanosheets are mass-produced by controlling the ultrasonic power and time, or the shear rate and time of a homogenizer. These nanosheets are then centrifuged to obtain indium selenide nanosheets with relatively uniform thickness. This preparation method is simple, convenient, and operates under mild conditions. It does not require complex and expensive equipment, exhibits good reproducibility, and produces high-yield and high-purity products. Compared with current mechanical exfoliation and chemical vapor deposition methods, it has significant advantages, yielding indium selenide nanosheets with controllable thickness and large lateral dimensions, facilitating low-cost, mass production of indium selenide two-dimensional materials. Higher yields and smaller indium selenide nanosheets can be achieved by increasing the ultrasonic power / homogenizer speed or the exfoliation time.

[0059] The indium selenide nanosheets prepared by the method provided in this invention are two-dimensional materials that meet certain processing convenience requirements and possess excellent electrical properties, making them applicable to fields such as electronic devices and solar cells. In some embodiments, the thickness of the indium selenide nanosheets is 1-50 atomic layers, corresponding to a thickness of 0.8-41.5 nm. In some embodiments, the lateral dimensions of the indium selenide nanosheets are 0.8-50 μm.

[0060] InSe-Ag

[0061] This invention also provides a method for preparing an indium selenide nanosheet and silver nanoparticle composite, comprising the following steps:

[0062] (1) Add silver nitrate solution dropwise to the dispersion of indium selenide nanosheets, or add silver nitrate solution dropwise to the indium selenide dispersion;

[0063] (2) Centrifuge the above mixture and collect the precipitate. The precipitate is a composite structure of indium selenide nanosheets and silver nanoparticles.

[0064] This invention creatively utilizes the spontaneous redox reaction between indium selenide and silver nitrate to grow strongly absorbing silver nanoparticles on the surface of indium selenide, resulting in a stronger photoelectric response. This invention does not use any other catalysts, reducing agents, or other auxiliary agents, and prepares the composite structure of indium selenide and silver nanoparticles in a one-step process.

[0065] The mass ratio of silver nanoparticles to indium selenide can be controlled by adjusting the amounts of the reactants silver nitrate and indium selenide. Simultaneously, the size of the silver nanoparticles can be modulated by the concentration of silver nitrate, and the light absorbance of the composite can be controlled to some extent by the mass ratio of silver to indium selenide.

[0066] The concentration of silver nitrate is 0.01-100 mg / mL. If the concentration is too low, a large volume of solvent is required; if the concentration is too high, it is not conducive to uniform contact with InSe (requiring higher stirring speed for dispersion), resulting in uneven silver particle size and uneven dispersion of silver particles on InSe. In some examples, the concentration of silver nitrate is 0.1-10 mg / mL.

[0067] During the process of adding silver nitrate / indium selenide dropwise to the indium selenide / silver nitrate solution, the indium selenide / silver nitrate solution is subjected to ultrasonic and magnetic / mechanical stirring.

[0068] This invention utilizes a spontaneous redox reaction between indium selenide and silver chloride to grow strongly absorbing silver nanoparticles on the surface of indium selenide, resulting in a stronger photoelectric response. Therefore, developing a convenient and inexpensive preparation method is beneficial for practical applications. Furthermore, using other substances as reducing or oxidizing agents can easily introduce impurities; therefore, the method of this invention can reduce the introduction of impurities.

[0069] Based on the above technical solutions, the indium selenide nanosheets and silver nanoparticle composites provided in this invention can be applied in ultrafast electronic devices, solar cells, biomedical detection, and other fields. The ultrafast electronic devices may include photoelectric sensors and gas sensors.

[0070] The advantages of the embodiments of the present invention will be set forth in part in the description which follows, and in part will be obvious from the description or may be learned by practicing the embodiments of the present invention.

[0071] The embodiments of the present invention will be further described below with reference to several examples, but the embodiments of the present invention are not limited thereto.

[0072] Example 1

[0073] A method for preparing indium selenide nanosheets includes the following steps:

[0074] (1) Weigh 300mg of bulk indium selenide and put it into 10mL of anhydrous NMP. Perform water bath sonication at 300W for 6 hours (the ultrasonic instrument used is an ultrasonic cleaner, model KQ-300DE, from Kunshan Ultrasonic Instrument Co., Ltd.). During the water bath sonication, use an ice-water mixture to control the temperature at 10℃ to prevent the indium selenide from oxidizing and deteriorating due to excessive temperature, and obtain the ultrasonic liquid.

[0075] (2) The above homogenate was centrifuged at 2000 rpm for 1 min, and the supernatant was collected; the supernatant was then centrifuged at 7000 rpm for 6 min, and the precipitate was collected. The obtained precipitate was indium selenide nanosheets. The morphology of the crude product was observed under a transmission electron microscope, such as... Figure 2 As shown in Figure a, most of the products have a size of 200-1000nm, while some have a size of 20-100nm. The surface is smooth and flat with sharp edges, indicating that the crystallinity is intact and no obvious oxidation has occurred.

[0076] Example 2

[0077] A method for preparing indium selenide nanosheets includes the following steps:

[0078] (1) 300 mg of bulk indium selenide was added to 10 mL of anhydrous isopropanol and homogenized using a homogenizer (Germany IKAT25digital) at 20 k rpm for 20 min to obtain a homogenate. During this process, the room temperature was 25 °C, and the temperature of the homogenate was controlled at 15-23 °C using circulating water;

[0079] (2) The above homogenate was centrifuged at 2000 rpm for 1 min and the supernatant was collected; the supernatant was centrifuged at 7000 rpm for 6 min and the precipitate was collected. The obtained precipitate was indium selenide nanosheets, which were dried under vacuum and then X-ray diffraction pattern was tested. Figure 1 The X-ray diffraction pattern of the indium selenide nanosheets prepared in this embodiment is shown in the figure. The product has good crystallinity and no other impurity diffraction peaks. The product's morphology was observed under a transmission electron microscope, as shown in the figure. Figure 2 As shown in Figure b, most of the products are 200-1000 nm in size, with some ranging from 20-100 nm. The products also exhibit a smooth, flat surface and sharp edges, indicating good crystallinity.

[0080] Example 3

[0081] A method for preparing indium selenide nanosheets includes the following steps:

[0082] (1) 300 mg of bulk indium selenide was added to 10 mL of anhydrous NMP and homogenized using a homogenizer (IKA T25digital, Germany) at 20 k rpm for 20 min to obtain a homogenate. During this process, the room temperature was 25 °C, and the temperature of the homogenate was controlled at 23 °C using circulating water.

[0083] (2) Centrifuge the above homogenate at a low speed of 6000 rpm for 2 min, gently aspirate 1 / 2 of the supernatant, centrifuge it at a high speed of 7500 rpm for 2 min, collect the precipitate, and the obtained precipitate is indium selenide nanosheets.

[0084] The product was observed under a transmission electron microscope to examine its morphology, such as... Figure 3 As shown in Figure a, the product size distribution is uniform, ranging from 300 to 1000 nm. This indicates that two centrifugations can separate products with more uniform size. Furthermore, the smooth and flat surface of the product with sharp edges indicates good crystallinity.

[0085] Example 4

[0086] A method for preparing an indium selenide nanosheet and silver nanoparticle composite includes the following steps:

[0087] (1) The indium selenide nanosheets obtained in Example 3 were dispersed in NMP, DMSO and water respectively, and the concentration was adjusted to 1 mg / mL, with each portion being 0.2 mL.

[0088] (2) The above indium selenide dispersion was added dropwise to silver nitrate aqueous solutions with silver concentrations of 0.1, 0.5, and 0.02 mg / mL (volumes of 0.2 mL, 0.04 mL, and 1 mL, respectively). The mixture was stirred while being added dropwise. After sonication for 1 min, the mixture was centrifuged at 18000 rpm for 5 min and the precipitate was collected. This was the composite structure of indium selenide nanosheets and silver nanoparticles.

[0089] (3) Figure 3 bd are transmission electron microscopy (TEM) images of the composite structure (corresponding to silver concentrations of 0.1, 0.5, and 0.02 mg / mL, respectively, and a mass ratio of indium selenide nanosheets to silver nitrate of 10:1). It can be seen that the silver nanoparticles are almost entirely loaded onto the indium selenide surface and are uniformly dispersed thereon.

[0090] X-ray photoelectron spectroscopy was used to analyze the elemental composition and valence state changes of indium selenide nanosheets before and after silver nitrate treatment. The results are as follows: Figure 9 As shown. InSe has a layered structure, and Se is usually in the -2 valence (Se... 2 It exists in the form of -). The ratio of the peak intensity of Se3d3 / 2 to that of Se3d5 / 2 in InSe-Ag is significantly weakened, which means that the oxidation state of Se is reduced (e.g., from -2 to close to 0). This is because in this redox reaction, silver nitrate is the oxidant and indium selenide is the reducing agent, and the Se2- ions on the surface are oxidized.

[0091] Example 5

[0092] A method for preparing an indium selenide nanosheet and silver nanoparticle composite includes the following steps:

[0093] (1) The indium selenide nanosheets obtained in Example 3 were dispersed in water and the concentration was adjusted to 5 mg / mL. The mixture was divided into several portions of 0.8 mL each.

[0094] (2) 0.2 mL of silver nitrate aqueous solutions with silver concentrations of 0.25, 0.5, 1, and 2 mg / mL were added dropwise to the above indium selenide dispersion (while stirring). After centrifugation at 18000 rpm for 5 min, the precipitate was collected, which is the composite structure of indium selenide nanosheets and silver nanoparticles.

[0095] like Figure 4 As shown in the AD diagram, the silver nanoparticles are almost entirely loaded on the surface of indium selenide and are uniformly dispersed on the surface of indium selenide.

[0096] Example 6

[0097] A method for preparing an indium selenide nanosheet and silver nanoparticle composite includes the following steps:

[0098] (1) The indium selenide nanosheets obtained in Example 3 were dispersed in NMP and the concentration was adjusted to 1 mg / mL. The mixture was divided into several portions of 0.6 mL each.

[0099] (2) The above indium selenide dispersion was added dropwise to 0.2 mL of silver nitrate aqueous solution with silver concentrations of 0, 0.06, 0.15, 0.30 and 0.60 mg / mL respectively (while stirring). After centrifugation at 9000 rpm for 5 min, the precipitate was collected, which is the indium selenide nanosheet and silver nanoparticle composite (the mass percentages of silver and indium selenide are 0, 2%, 5%, 10% and 20% respectively).

[0100] (3) Disperse the precipitate obtained above in 10 mL of ethanol solution and test the absorption, such as... Figure 5 As shown, in the visible light band, the absorbance of the composite material increases with the increase of silver loading.

[0101] Example 7

[0102] A method for preparing an indium selenide nanosheet and silver nanoparticle composite includes the following steps:

[0103] (1) Indium selenide was peeled off using adhesive tape and transferred onto a silicon wafer. The microstructure of indium selenide under a scanning electron microscope is shown below. Figure 6 a;

[0104] (2) A silver nitrate solution with a concentration of 1 mg / mL was added to the silicon wafer. After 5 seconds, the solution was blown off with nitrogen gas. The morphology under a scanning electron microscope is as follows. Figure 6 b. Silver nanoparticles (size 20-40 nm) can be seen growing on the indium selenide nanosheets.

[0105] Example 8

[0106] A method for fabricating a photodetector includes the following steps:

[0107] (1) According to the mass ratio m(polyvinylidene fluoride):m(indium selenide nanosheets) = 1:10, a certain amount of polyvinylidene fluoride was added to an anhydrous ethanol dispersion of indium selenide nanosheets and silver nanoparticles with a concentration of 1 mg / mL (prepared in an NMP environment in Example 4. The control group was the indium selenide nanosheets obtained in Example 3). The mixture was magnetically stirred at 600 rpm until the polyvinylidene fluoride was completely dissolved.

[0108] (2) Add 1 mL of the above dispersion to the conductive side of an ITO glass with a length × width × height of 3 × 1 × 0.2 cm (this size is adjustable), and store it under vacuum for 8 hours to completely evaporate the liquid, thus obtaining a photodetector based on a composite structure. Then wipe off the 1 × 1 cm composite structure at one end with an alcohol swab so that the ITO can contact the working electrode.

[0109] A saturated calomel electrode and a platinum electrode are provided. The working electrode, the Ag / AgCl electrode (i.e., the reference electrode), and the platinum electrode (i.e., the counter electrode) are placed in a KOH aqueous solution (i.e., the electrolyte) and assembled into a three-electrode system to obtain a photodetector based on a composite structure.

[0110] To test the performance of the photodetector, an electrochemical workstation, a simulated light source, and an optical chopper are provided. The three-electrode system is connected to the electrochemical workstation for electrochemical testing. The simulated solar light source is used to emit simulated sunlight. Figure 7 This is a schematic diagram of the test of the photodetector prepared in Example 8 (E1 is the working electrode, E2 is the platinum electrode, and E3 is the saturated calomel electrode). The voltage difference (bias voltage) between the working electrode and the reference electrode can be adjusted. The photocurrent obtained in the test is the current between the working electrode and the counter electrode. Light emitted from the simulated light source is modulated by an optical chopper and irradiates the working electrode, inducing a photocurrent. The signal is output through the electrochemical workstation and displayed on the computer screen.

[0111] Figure 8 'a' represents the current of InSe and InSe-Ag under darkness and illumination (optical power density of 20 mW / cm²). 2 ), Figure 8 b represents the photocurrent under simulated sunlight (photocurrent calculation method: current under illumination - current under darkness). It can be seen that compared with indium selenide, the photocurrent of the indium selenide nanosheet composite is significantly improved. The photocurrent is significantly improved under a bias voltage of -0.2-0.6V, and the photocurrent without an applied bias voltage is 5.5 times that of indium selenide.

[0112] Photocurrent at zero bias: InSe-Ag photocurrent is 0.208 μA at zero bias (InSe in Example 3 photocurrent is 0.038 μA at zero bias). Figure 8 b).

[0113] Comparative Example 1

[0114] A method for preparing an indium selenide nanosheet and silver nanoparticle composite includes the following steps:

[0115] (1) The indium selenide nanosheets obtained in Example 2 were dispersed in isopropanol and the concentration was adjusted to 1 mg / mL and 0.2 mL respectively.

[0116] (2) The above indium selenide dispersion was added dropwise to silver nitrate aqueous solution with silver concentration of 0.1 mg / mL, with a volume of 0.2 mL. The mixture was stirred while being added dropwise, and then sonicated for 1 min. After centrifugation at 18000 rpm for 5 min, the precipitate was collected, which is the composite structure of indium selenide nanosheets and silver nanoparticles.

[0117] Figure 10 The transmission electron microscope (TEM) image of the composite prepared as a comparative example of benzene is shown in the figure. Almost all the silver nanoparticles are loaded on the surface of indium selenide, but... Figure 3 In comparison, it can be observed that the silver particles are not uniform on the surface of indium selenide. This is because indium selenide is dispersed with isopropanol, which readily absorbs water vapor from the air, causing some indium selenide nanosheets to oxidize first. Their higher surface activity makes them more prone to redox reactions with silver nitrate.

[0118] Following the steps of preparing the working electrode in Example 8, the composite prepared in this example was used to prepare the working electrode, and the photocurrent was measured to be 0.075 μA under zero bias.

[0119] Comparing the photocurrents of the InSe-Ag electrodes in Example 8 and Comparative Example 1, it was found that Example 8 had the largest photocurrent. This is because the Ag particles are uniformly distributed on the InSe, which can effectively conduct electrons. In contrast, the Ag distribution in Comparative Example 1 is uneven, and it cannot effectively conduct electrons.

[0120] Comparative Example 2

[0121] A method for preparing an indium selenide nanosheet and silver nanoparticle composite includes the following steps:

[0122] (1) The indium selenide nanosheets obtained in Example 3 were dispersed in NMP and the concentration was adjusted to 1 mg / mL and 2 mL respectively.

[0123] (2) The above indium selenide dispersion was added dropwise to silver nitrate aqueous solution with silver concentration of 20 mg / mL, with a volume of 10 μL. The mixture was stirred while being added dropwise, and then sonicated for 1 min. After centrifugation at 18000 rpm for 5 min, the precipitate was collected, which is the composite structure of indium selenide nanosheets and silver nanoparticles.

[0124] Figure 11The image shows a transmission electron microscope (TEM) image of the composite prepared in this comparative example. As shown in the figure, the silver nanoparticles are almost entirely loaded on the surface of indium selenide, but... Figure 3 In comparison, it can be observed that the silver particles are not uniform on the surface of indium selenide. This is because the high-concentration silver nitrate solution reacts with some of the indium selenide before it is evenly mixed with it, resulting in some indium selenide areas having no silver particles.

[0125] The composite obtained in this comparative example was prepared into a working electrode according to the relevant steps in Example 8, and the photocurrent was measured to be 0.082 μA under zero bias. Comparing the photocurrents of the InSe-Ag electrodes of Example 8 and Comparative Example 2, it was found that the photocurrent of Example 8 was the largest. This is because the Ag particles are uniformly distributed on InSe, which can effectively conduct electrons. In contrast, the Ag distribution in Comparative Example 2 is not uniform, and it cannot effectively conduct electrons.

[0126] Comparative Example 3

[0127] A method for preparing an indium selenide nanosheet and silver nanoparticle composite structure includes the following steps:

[0128] (1) The indium selenide nanosheets obtained in Example 3 were dispersed in NMP and the concentration was adjusted to 20 mg / mL, 10 μL.

[0129] (2) The above indium selenide dispersion was added dropwise to silver nitrate aqueous solution with silver concentration of 0.1 mg / mL, with a volume of 0.2 mL. The mixture was stirred while being added dropwise, and then sonicated for 1 min. After centrifugation at 18000 rpm for 5 min, the precipitate was collected, which is the composite structure of indium selenide nanosheets and silver nanoparticles.

[0130] Figure 12 The image shows a transmission electron microscope (TEM) image of the composite prepared in this comparative example. As shown in the figure, silver nanoparticles are present not only on the surface of indium selenide but also in other locations. This is because the silver particles produced by the reaction have weak adhesion to indium selenide due to the use of a high-concentration indium selenide dispersion, and are partially dispersed in the solution under ultrasonication.

[0131] The composite obtained in this comparative example was prepared into a working electrode according to the relevant steps in Example 8, and the photocurrent was measured to be 0.105 μA under zero bias. Comparing the photocurrents of the InSe-Ag electrodes of Example 8 and Comparative Example 3, it was found that the photocurrent of Example 8 was the largest. This is because the Ag particles are uniformly distributed on the InSe, which can effectively conduct electrons. In contrast, the Ag in Comparative Example 3 was not fully loaded on the InSe surface, and the photocurrent was also weaker.

[0132] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an indium selenide nanosheet composite, characterized in that, The preparation method includes: mixing indium selenide nanosheets with silver ions in a second solvent to grow silver nanoparticles on the surface of the indium selenide nanosheets. The second solvent is selected as a polar solvent, and the Hansen solubility parameter δ of the third solvent is ≥18 MPa. 1 / 2 , The mass ratio of the indium selenide nanosheets to the silver ions is (5-50):

1.

2. The preparation method according to claim 1, characterized in that, The silver ions are selected as soluble silver salts capable of providing silver ions in the second solvent; and / or The second solvent is selected from at least one of water, N-methylpyrrolidone, and dimethyl sulfoxide.

3. The preparation method according to claim 1, characterized in that, The steps of mixing indium selenide nanosheets with silver ions in a second solvent include: Indium selenide nanosheets are dispersed in the second solvent to form an indium selenide nanosheet dispersion. An aqueous solution of silver nitrate is then added dropwise to the indium selenide nanosheet dispersion while stirring continuously using ultrasonic stirring, magnetic stirring, or mechanical stirring. Indium selenide nanosheets are dispersed in the second solvent to form an indium selenide nanosheet dispersion. The indium selenide nanosheet dispersion is then added dropwise to an aqueous solution of silver nitrate while stirring, using ultrasonic stirring, magnetic stirring, or mechanical stirring.

4. The preparation method according to claim 1, characterized in that, In the mixing process, the concentration of the indium selenide nanosheets in the second solvent is 0.01-100 mg / mL, or In the mixing process, the concentration of the indium selenide nanosheets in the second solvent is 0.1-10 mg / mL.

5. The preparation method according to claim 1, characterized in that, Indium selenide nanosheets were mixed with silver nitrate in a second solvent, wherein the concentration of silver nitrate was 0.01-100 mg / mL, or Indium selenide nanosheets are mixed with silver nitrate in a second solvent, wherein the concentration of silver nitrate is 0.1-10 mg / mL.

6. The preparation method according to any one of claims 1 to 5, characterized in that, The indium selenide nanosheets have an average thickness of 0.8-83 nm and an average lateral dimension of 0.1-50 μm. and / or The step of mixing indium selenide nanosheets with silver ions in a second solvent includes: mixing indium selenide nanosheets with silver nitrate in a second solvent, wherein the mass ratio of indium selenide nanosheets to silver nitrate is (10-100):

1.

7. The preparation method according to any one of claims 1 to 5, characterized in that, The preparation method of the indium selenide nanosheets includes the following steps: (1) The indium selenide block is placed in the first solvent and sealed, and ultrasonicated at 100-600W for 1-96 hours to obtain ultrasonic liquid, or sheared in a homogenizer at a rate of 0.3k-25k rpm for 1s-72h to obtain homogenized liquid; (2) The ultrasonic liquid or the homogenate is centrifuged at a low speed of 100-4000 rpm and the supernatant is collected; and the supernatant is centrifuged at a high speed of 1000-18000 rpm, wherein the speed of the high speed centrifugation is at least 120% of the speed of the low speed centrifugation, and the precipitate is collected. The precipitate obtained is indium selenide nanosheets.

8. The preparation method according to claim 7, wherein the first solvent is N-methylpyrrolidone (NMP).

9. The indium selenide nanosheet composite prepared by the preparation method according to any one of claims 1-8.

10. The application of the indium selenide nanosheet composite prepared by the preparation method according to any one of claims 1-8 in ultrafast electronic devices, solar cells, and biomedical detection.

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