Black phosphorus and silver nanowire heterojunction composite material and its preparation method and application

Abstract

The present invention discloses a black phosphorus and silver nanowire heterojunction composite material and its preparation method and application. The preparation of the composite material includes: obtaining large-sized two-dimensional black phosphorus nanosheets by electrochemical dissociation of black phosphorus single crystal technology; placing the large-sized two-dimensional black phosphorus nanosheets in N-methylpyrrolidone solution, ultrasonically crushing in an ice bath environment, and obtaining a two-dimensional black phosphorus nanosheet dispersion; centrifuging the two-dimensional black phosphorus nanosheet dispersion, extracting the supernatant, and obtaining ultrathin two-dimensional black phosphorus nanosheets, and after vacuum filtration, washing and vacuum drying, obtaining two-dimensional black phosphorus nanosheets; ultrasonically dispersing the two-dimensional black phosphorus nanosheets and silver nanowires in the solution and letting it stand to self-assemble, and after vacuum filtration, washing and vacuum drying, obtaining a heterojunction of black phosphorus and silver nanowires. The black phosphorus nanosheet and silver nanowire heterojunction prepared by the present invention can fully expose the excellent active sites of black phosphorus, enhance the electron transfer rate of the system, and has significant application value in the energy field.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterial preparation, and in particular relates to a black phosphorus and silver nanowire heterojunction composite material, a preparation method and an application thereof. Background Art

[0002] In recent years, with the increasing development of science and technology, smart electronic products have brought many conveniences to people's daily lives. This, in turn, has further stimulated the demand for new smart electronic products. The development of smart electronic products faces many challenges, and the development and utilization of high-energy-density energy supply systems is one of the key issues. Supercapacitors are devices that store energy by forming an interfacial double layer or undergoing a reversible redox reaction between electrodes and electrolytes. With their advantages such as long service life, strong environmental adaptability, high charge and discharge efficiency, and high power density, they have shown great application value and market potential in mobile communications, smart grids, distributed energy storage, urban rail transit, and military equipment. However, supercapacitors lag far behind lithium-ion batteries in terms of energy density. Improving the energy per unit volume (i.e., energy density) is currently the focus and difficulty of research in the supercapacitor field. The physicochemical properties of electrode materials are closely related to the electrochemical energy storage performance of energy storage devices. Therefore, the development of new electrode materials is key to solving these problems.

[0003] Two-dimensional materials, such as graphene, offer advantages such as large surface area, short ion transport pathways, and excellent mechanical properties, demonstrating broad application prospects in supercapacitors. Among these two-dimensional materials, black phosphorus, with its wrinkled layer structure and excellent electrical conductivity, has attracted widespread attention in the field of electrochemical capacitor energy storage. However, the slow electron / ion diffusion rate and low capacitance storage capacity in black phosphorus supercapacitors result in poor rate performance, low cycling stability, and low energy density. Summary of the Invention

[0004] In response to the above problems, the present invention aims to provide a black phosphorus and silver nanowire heterojunction composite material and its preparation method and application, so as to fully expose more active sites in black phosphorus nanosheets, enhance the electron transport ability of the system, and thus obtain optimal energy storage performance.

[0005] The specific technical solutions of the present invention are as follows:

[0006] The present invention provides a method for preparing a black phosphorus and silver nanowire heterojunction composite material, comprising the following steps:

[0007] (1) A black phosphorus single crystal block is placed in a dimethyl sulfoxide solution containing tetrabutylammonium bromide, with black phosphorus as the negative electrode and a platinum electrode as the positive electrode, and electrochemically dissociated. After vacuum filtration, washing, and vacuum drying, large-sized two-dimensional black phosphorus nanosheets are obtained.

[0008] (2) placing the large-sized two-dimensional black phosphorus nanosheets obtained in step (1) in an N-methylpyrrolidone solution and ultrasonically crushing them in an ice bath environment to obtain a two-dimensional black phosphorus nanosheet dispersion;

[0009] (3) centrifuging the two-dimensional black phosphorus nanosheet dispersion obtained in step (2), extracting the supernatant to obtain ultrathin two-dimensional black phosphorus nanosheets, and then vacuum filtering, washing, and vacuum drying to obtain two-dimensional black phosphorus nanosheets;

[0010] (4) The two-dimensional black phosphorus nanosheets and silver nanowires obtained in step (3) are ultrasonically dispersed in a solution and allowed to stand to self-assemble, and then vacuum filtered, washed and vacuum dried to obtain a heterojunction of black phosphorus and silver nanowires.

[0011] Furthermore, the concentration of tetrabutylammonium bromide in the dimethyl sulfoxide solution containing tetrabutylammonium bromide is 0.01-0.1 mol / L;

[0012] And / or, the potential difference of the electrochemical dissociation is 1-10 V, and the dissociation time is 10-60 min.

[0013] Furthermore, in step (1), step (3) and step (4), the vacuum drying temperature is 50-100°C.

[0014] Furthermore, in step (2), the ultrasonic pulverization power is 200-800 W, and the time is 2-120 min.

[0015] Furthermore, in step (3), the centrifugal speed is 1000-8000 rpm, and the time is 40-120 min.

[0016] Furthermore, in step (4), the mass ratio of the two-dimensional black phosphorus nanosheets to the silver nanowires is 1:(1-10);

[0017] Preferably, the silver nanowires have a length of 5-50 μm and a diameter of 30-100 nm.

[0018] Furthermore, in step (4), the ultrasonic dispersion power is 300-800 W, and the time is 2-60 min.

[0019] Furthermore, in step (4), the resting time is 1 to 10 hours.

[0020] The present invention also provides a black phosphorus and silver nanowire heterojunction composite material prepared by the preparation method.

[0021] The present invention also provides application of the black phosphorus and silver nanowire heterojunction composite material in a supercapacitor.

[0022] The beneficial effects of the present invention are:

[0023] a) This invention utilizes electrochemical dissociation of black phosphorus single crystals to produce large-scale two-dimensional black phosphorus nanosheets. This electrochemical dissociation rapidly drives cations in the electrolyte into the interlayers of the black phosphorus. The cations decompose under negative potential, disrupting the van der Waals forces between the black phosphorus layers and exfoliating the black phosphorus, yielding a large number of two-dimensional black phosphorus nanosheets.

[0024] b) The present invention further utilizes ultrasonic dispersion technology to obtain a mixed solution of black phosphorus nanosheets and silver nanowires. This technology can disperse the two uniformly, which is conducive to the preparation of a large number of black phosphorus nanosheets and silver nanowire heterojunctions.

[0025] c) The black phosphorus nanosheet and silver nanowire heterojunction prepared by the present invention can fully expose the active sites of the black phosphorus nanosheet, effectively enhance the electron transfer between the black phosphorus and silver nanowires, and has the advantages of large-scale production and significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is the XRD pattern of black phosphorus crystal;

[0027] Figure 2 Raman image of two-dimensional black phosphorus nanosheets;

[0028] Figure 3 TEM image of two-dimensional black phosphorus nanosheets;

[0029] Figure 4 AFM image of two-dimensional black phosphorus nanosheets;

[0030] Figure 5 TEM image of silver nanowires;

[0031] Figure 6 a is the TEM image of the black phosphorus and silver nanowire heterojunction;

[0032] Figure 6 b is a high-angle annular dark-field image of a black phosphorus and silver nanowire heterojunction;

[0033] Figure 6 c, 6d are EDS images of black phosphorus and silver nanowire heterojunctions;

[0034] Figure 7 Impedance diagram of supercapacitors based on black phosphorus and black phosphorus and silver nanowire heterojunctions. DETAILED DESCRIPTION

[0035] To more clearly understand the present invention, the present invention is further described with reference to the following examples and accompanying drawings. The examples are intended to illustrate the present invention only and are not intended to limit the present invention in any way. In the examples, all raw materials and reagents are commercially available. Experimental methods without specific conditions are conventional methods and conditions well known in the art, or according to the conditions recommended by the instrument manufacturer. Example 1

[0036] This embodiment provides a method for preparing a black phosphorus and silver nanowire heterojunction composite material, comprising the following steps:

[0037] (1) Cutting black phosphorus crystals to obtain long black phosphorus blocks; placing black phosphorus in a dimethyl sulfoxide solution containing 0.01 mol / L tetrabutylammonium bromide, with black phosphorus as the negative electrode and a platinum electrode as the positive electrode, applying a bias voltage of 4 volts, and electrochemically dissociating for 10 minutes, followed by vacuum filtration, washing, and vacuum drying (100°C) to obtain large-sized two-dimensional black phosphorus nanosheets.

[0038] Figure 1 The XRD pattern of the large-sized two-dimensional black phosphorus nanosheets obtained is compared with the standard PDF card, which shows that high-purity black phosphorus nanosheets have been successfully obtained. Figure 2 This is the Raman graph of the two-dimensional black phosphorus nanosheet. The three peaks in the graph correspond to the three characteristic peaks of black phosphorus. 、 and . Figure 3 This is a TEM image of two-dimensional black phosphorus nanosheets, the size of which is at the micron level. Figure 4 This is an AFM image of a two-dimensional black phosphorus nanosheet, showing that the thickness of the two-dimensional black phosphorus nanosheet is 4-8 nanometers.

[0039] (2) The large-sized two-dimensional black phosphorus nanosheets obtained in step (1) were placed in an N-methylpyrrolidone solution and ultrasonically crushed in an ice bath for 1 hour at an ultrasonic power of 500 W to obtain a two-dimensional black phosphorus nanosheet dispersion.

[0040] (3) The two-dimensional black phosphorus nanosheet dispersion obtained in step (2) is centrifuged at a centrifugal speed of 1000 rpm. After centrifugation for 1 hour, the supernatant is extracted to obtain ultrathin two-dimensional black phosphorus nanosheets, which are then vacuum filtered, washed, and vacuum dried (100°C) to obtain two-dimensional black phosphorus nanosheets.

[0041] (4) The two-dimensional black phosphorus nanosheets obtained in step (3) and silver nanowires (length range: 5-50 μm, diameter range: 30-100 nm) were ultrasonically dispersed (ultrasonic power of 500 W, time for 30 minutes) in a solution at a mass ratio of 1:1, and allowed to stand for 1 hour to allow self-assembly. After vacuum filtration, washing and vacuum drying (100°C), a heterojunction of black phosphorus and silver nanowires was obtained.

[0042] Figure 5 This is a TEM image of silver nanowires, which can reach micrometer levels in length. Figure 6 a is the TEM image of the black phosphorus and silver nanowire heterojunction. It can be seen that the black phosphorus nanosheets uniformly cover the silver nanowires, proving the successful preparation of the black phosphorus and silver nanowire heterojunction. Figure 6 b: High-angle annular dark-field image of the black phosphorus and silver nanowire heterojunction. Figure 6 c, 6d are energy spectrum images of the black phosphorus and silver nanowire heterojunction, in which phosphorus and silver elements are evenly distributed.

[0043] Figure 7 The impedance graphs of supercapacitors based on black phosphorus and black phosphorus / silver nanowire heterojunctions are shown. Across the entire frequency range, the slope of the impedance spectrum of the black phosphorus / silver nanowire heterojunction supercapacitor is higher at low frequencies than that of the black phosphorus supercapacitor, and the imaginary part increases rapidly, approaching 90°. This indicates that the ion migration rate of the black phosphorus / silver nanowire heterojunction is higher than that of the black phosphorus device. At high frequencies, the device resistance of the black phosphorus / silver nanowire heterojunction is lower than that of the black phosphorus device. Therefore, the black phosphorus / silver nanowire heterojunction structure effectively exposes active sites in the black phosphorus nanosheets, enhancing their ion migration rate and reducing device resistance, resulting in better energy storage performance. Example 2

[0044] This embodiment provides a method for preparing a black phosphorus and silver nanowire heterojunction composite material, comprising the following steps:

[0045] (1) Cutting black phosphorus crystals to obtain long black phosphorus blocks; placing black phosphorus in a dimethyl sulfoxide solution containing 0.05 mol / L tetrabutylammonium bromide, with black phosphorus as the negative electrode and a platinum electrode as the positive electrode, applying a bias voltage of 6 volts, and electrochemically dissociating for 20 minutes, followed by vacuum filtration, washing, and vacuum drying (80°C) to obtain large-sized two-dimensional black phosphorus nanosheets.

[0046] (2) The large-sized two-dimensional black phosphorus nanosheets obtained in step (1) were placed in an N-methylpyrrolidone solution and ultrasonically crushed in an ice bath for 2 hours at an ultrasonic power of 200 W to obtain a two-dimensional black phosphorus nanosheet dispersion.

[0047] (3) The two-dimensional black phosphorus nanosheet dispersion obtained in step (2) is centrifuged at a centrifugal speed of 2000 rpm. After centrifugation for 2 hours, the supernatant is extracted to obtain ultrathin two-dimensional black phosphorus nanosheets, which are then vacuum filtered, washed, and vacuum dried (80°C) to obtain two-dimensional black phosphorus nanosheets.

[0048] (4) The two-dimensional black phosphorus nanosheets obtained in step (3) and silver nanowires (length range: 5-50 μm, diameter range: 30-100 nm) were ultrasonically dispersed (ultrasonic power of 300 W, time for 60 minutes) in a solution at a mass ratio of 1:2, and allowed to stand for 3 hours to allow self-assembly. After vacuum filtration, washing and vacuum drying (80°C), a heterojunction of black phosphorus and silver nanowires was obtained. Example 3

[0049] This embodiment provides a method for preparing a black phosphorus and silver nanowire heterojunction composite material, comprising the following steps:

[0050] (1) Cutting black phosphorus crystals to obtain long black phosphorus blocks; placing black phosphorus in a dimethyl sulfoxide solution containing 0.07 mol / L tetrabutylammonium bromide, with black phosphorus as the negative electrode and a platinum electrode as the positive electrode, applying a bias voltage of 8 volts, and electrochemically dissociating for 30 minutes, followed by vacuum filtration, washing, and vacuum drying (100°C) to obtain large-sized two-dimensional black phosphorus nanosheets.

[0051] (2) The large-sized two-dimensional black phosphorus nanosheets obtained in step (1) were placed in an N-methylpyrrolidone solution and ultrasonically crushed in an ice bath for 1 hour at an ultrasonic power of 500 W to obtain a two-dimensional black phosphorus nanosheet dispersion.

[0052] (3) The two-dimensional black phosphorus nanosheet dispersion obtained in step (2) is centrifuged at a centrifugal speed of 5000 rpm. After centrifugation for 1 hour, the supernatant is extracted to obtain ultrathin two-dimensional black phosphorus nanosheets, which are then vacuum filtered, washed, and vacuum dried (100°C) to obtain two-dimensional black phosphorus nanosheets.

[0053] (4) The two-dimensional black phosphorus nanosheets obtained in step (3) and silver nanowires (length range: 5-50 μm, diameter range: 30-100 nm) were ultrasonically dispersed (ultrasonic power of 500 W, time for 30 minutes) in a solution at a mass ratio of 1:4, and allowed to stand for 5 hours to allow self-assembly. After vacuum filtration, washing and vacuum drying (100°C), a heterojunction of black phosphorus and silver nanowires was obtained. Example 4

[0054] This embodiment provides a method for preparing a black phosphorus and silver nanowire heterojunction composite material, comprising the following steps:

[0055] (1) Cutting black phosphorus crystals to obtain long black phosphorus blocks; placing black phosphorus in a dimethyl sulfoxide solution containing 0.05 mol / L tetrabutylammonium bromide, with black phosphorus as the negative electrode and a platinum electrode as the positive electrode, applying a bias voltage of 10 volts, and electrochemically dissociating for 60 minutes. After dissociation, vacuum filtration, washing, and vacuum drying (100°C) were performed to obtain large-sized two-dimensional black phosphorus nanosheets.

[0056] (2) The large-sized two-dimensional black phosphorus nanosheets obtained in step (1) were placed in an N-methylpyrrolidone solution and ultrasonically crushed in an ice bath for 2 hours at an ultrasonic power of 500 W to obtain a two-dimensional black phosphorus nanosheet dispersion.

[0057] (3) The two-dimensional black phosphorus nanosheet dispersion obtained in step (2) is centrifuged at a centrifugal speed of 2000 rpm. After centrifugation for 1 hour, the supernatant is extracted to obtain ultrathin two-dimensional black phosphorus nanosheets, which are then vacuum filtered, washed, and vacuum dried (100°C) to obtain two-dimensional black phosphorus nanosheets.

[0058] (4) The two-dimensional black phosphorus nanosheets obtained in step (3) and silver nanowires (length range: 5-50 μm, diameter range: 30-100 nm) were ultrasonically dispersed (ultrasonic power of 500 W, time for 30 minutes) in a solution at a mass ratio of 1:5 and allowed to stand for 7 hours to allow self-assembly. After vacuum filtration, washing and vacuum drying (100°C), a heterojunction of black phosphorus and silver nanowires was obtained. Example 5

[0059] This embodiment provides a method for preparing a black phosphorus and silver nanowire heterojunction composite material, comprising the following steps:

[0060] (1) Cutting black phosphorus crystals to obtain long black phosphorus blocks; placing black phosphorus in a dimethyl sulfoxide solution containing 0.1 mol / L tetrabutylammonium bromide, with black phosphorus as the negative electrode and a platinum electrode as the positive electrode, applying a bias voltage of 10 volts, and electrochemically dissociating for 30 minutes, followed by vacuum filtration, washing, and vacuum drying (100°C) to obtain large-sized two-dimensional black phosphorus nanosheets.

[0061] (2) The large-sized two-dimensional black phosphorus nanosheets obtained in step (1) were placed in an N-methylpyrrolidone solution and ultrasonically crushed in an ice bath for 1 hour at an ultrasonic power of 500 W to obtain a two-dimensional black phosphorus nanosheet dispersion.

[0062] (3) The two-dimensional black phosphorus nanosheet dispersion obtained in step (2) is centrifuged at a centrifugal speed of 5000 rpm. After centrifugation for 2 hours, the supernatant is extracted to obtain ultrathin two-dimensional black phosphorus nanosheets, which are then vacuum filtered, washed, and vacuum dried (100°C) to obtain two-dimensional black phosphorus nanosheets.

[0063] (4) The two-dimensional black phosphorus nanosheets obtained in step (3) and silver nanowires (length range: 5-50 μm, diameter range: 30-100 nm) were ultrasonically dispersed (ultrasonic power of 500 W, time for 30 minutes) in a solution at a mass ratio of 1:10, and allowed to stand for 10 hours to allow self-assembly. After vacuum filtration, washing and vacuum drying (100°C), a heterojunction of black phosphorus and silver nanowires was obtained.

[0064] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for preparing a black phosphorus and silver nanowire heterojunction composite material, characterized by comprising the following steps: (1) A black phosphorus single crystal block is placed in a dimethyl sulfoxide solution containing tetrabutylammonium bromide, with black phosphorus as the negative electrode and a platinum electrode as the positive electrode, and electrochemically dissociated. After vacuum filtration, washing, and vacuum drying, large-sized two-dimensional black phosphorus nanosheets are obtained. (2) placing the large-sized two-dimensional black phosphorus nanosheets obtained in step (1) in an N-methylpyrrolidone solution and ultrasonically crushing them in an ice bath environment to obtain a two-dimensional black phosphorus nanosheet dispersion; (3) centrifuging the two-dimensional black phosphorus nanosheet dispersion obtained in step (2), extracting the supernatant to obtain ultrathin two-dimensional black phosphorus nanosheets, and then vacuum filtering, washing, and vacuum drying to obtain two-dimensional black phosphorus nanosheets; (4) ultrasonically dispersing the two-dimensional black phosphorus nanosheets and silver nanowires obtained in step (3) in a solution and allowing them to stand to self-assemble, and then vacuum filtering, washing, and vacuum drying to obtain a heterojunction of black phosphorus and silver nanowires; The mass ratio of the two-dimensional black phosphorus nanosheets to the silver nanowires is 1:(1-10).

2. The preparation method according to claim 1, wherein In step (1), the concentration of tetrabutylammonium bromide in the dimethyl sulfoxide solution containing tetrabutylammonium bromide is 0.01-0.1 mol / L; And / or, the potential difference of the electrochemical dissociation is 1-10 V, and the dissociation time is 10-60 min.

3. The preparation method according to claim 1, characterized in that In step (1), step (3) and step (4), the vacuum drying temperature is 50-100°C.

4. The preparation method according to claim 1, wherein In step (2), the ultrasonic pulverization power is 200-800 W, and the time is 2-120 min.

5. The preparation method according to claim 1, wherein In step (3), the centrifugal speed is 1000-8000 rpm, and the time is 40-120 min.

6. The preparation method according to claim 1, wherein In step (4), the length of the silver nanowire is 5-50 μm and the diameter is 30-100 nm.

7. The preparation method according to claim 1, wherein In step (4), the ultrasonic dispersion power is 300-800 W, and the time is 2-60 min.

8. The preparation method according to claim 1, characterized in that In step (4), the resting time is 1 to 10 hours.

9. The black phosphorus and silver nanowire heterojunction composite material prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the black phosphorus and silver nanowire heterojunction composite material according to claim 9 in a supercapacitor.

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