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

Abstract

The invention discloses a black phosphorus and silver nanowire heterojunction composite material and a preparation method and application thereof. The preparation method of the composite material comprises the following steps: obtaining a large-size two-dimensional black phosphorus nanosheet through a black phosphorus single crystal electrochemical dissociation technology; the preparation method comprises the following steps: putting a large-size two-dimensional black phosphorus nanosheet into an N-methyl pyrrolidone solution, and carrying out ultrasonic crushing in an ice bath environment to obtain a two-dimensional black phosphorus nanosheet dispersion liquid; the two-dimensional black phosphorus nanosheet dispersion liquid is centrifuged, supernate is extracted, ultrathin two-dimensional black phosphorus nanosheets are obtained, and the two-dimensional black phosphorus nanosheets are obtained after vacuum filtration, washing and vacuum drying; the preparation method comprises the following steps: ultrasonically dispersing two-dimensional black phosphorus nanosheets and silver nanowires in a solution, standing, carrying out self-assembly, and carrying out vacuum filtration, washing and vacuum drying to obtain the heterojunction of black phosphorus and silver nanowires. According to the prepared black phosphorus nanosheet and silver nanowire heterojunction, excellent active sites of black phosphorus can be fully exposed, the electron transmission rate of a system is increased, and the heterojunction has great application value in the field of energy.

Description

Technical Field

[0001] The invention belongs to the technical field of nano material preparation, and specifically relates to a black phosphorus and silver nanowire heterojunction composite material and a preparation method and 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. In turn, it has stimulated the demand for new smart electronic products. The development of smart electronic products faces many problems, 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 between electrodes and electrolytes or by reversible redox reactions. With their long service life, strong environmental adaptability, high charging and discharging efficiency, and high power density, they have shown great application value and market potential in the fields of mobile communications, smart grids, distributed energy storage, urban rail transit, and military equipment. However, supercapacitors are far behind lithium-ion batteries in terms of energy density. Improving the energy per unit volume (i.e., energy density) is the current research focus and difficulty in the field of supercapacitors. The physical and chemical 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 the key to solving the above problems.

[0003] Two-dimensional materials represented by graphene have advantages such as large specific surface area, short ion transmission path, and excellent mechanical properties, showing broad application prospects in the field of supercapacitors. Among many two-dimensional materials, black phosphorus has attracted widespread attention in the field of electrochemical capacitor energy storage due to its wrinkled layer structure and excellent conductivity. However, the slow electron / ion diffusion rate and low capacitance storage capacity in black phosphorus supercapacitors lead to poor rate performance, low cycle stability and low energy density. Summary of the invention

[0004] In view of 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 and enhance the electron transmission ability of the system, thereby obtaining the best energy storage performance.

[0005] The specific technical solutions of the present invention are as follows: The present invention provides a method for preparing a black phosphorus and silver nanowire heterojunction composite material, comprising the following steps: (1) Placing a black phosphorus single crystal in a dimethyl sulfoxide solution containing tetrabutylammonium bromide, with black phosphorus as the negative electrode and a platinum electrode as the positive electrode, electrochemically dissociates the black phosphorus, and then obtains large-sized two-dimensional black phosphorus nanosheets after vacuum filtration, washing and vacuum drying; (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) The two-dimensional black phosphorus nanosheets and silver nanowires obtained in step (3) are ultrasonically dispersed in a solution and allowed to stand to allow them to self-assemble. After vacuum filtration, washing and vacuum drying, a heterojunction of black phosphorus and silver nanowires is obtained.

[0006] Furthermore, 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.

[0007] Furthermore, in step (1), step (3) and step (4), the vacuum drying temperature is 50-100°C.

[0008] Furthermore, in step (2), the power of the ultrasonic pulverization is 200-800 W, and the time is 2-120 min.

[0009] Furthermore, in step (3), the centrifugal speed is 1000-8000 rpm, and the time is 40-120 min.

[0010] Furthermore, in step (4), the mass ratio of the two-dimensional black phosphorus nanosheets to the silver nanowires is 1:(1-10); Preferably, the silver nanowire has a length of 5-50 μm and a diameter of 30-100 nm.

[0011] Furthermore, in step (4), the power of the ultrasonic dispersion is 300-800 W, and the time is 2-60 min.

[0012] Furthermore, in step (4), the static time is 1 to 10 hours.

[0013] The present invention also provides a black phosphorus and silver nanowire heterojunction composite material prepared by the preparation method.

[0014] The present invention also provides application of the black phosphorus and silver nanowire heterojunction composite material in a supercapacitor.

[0015] The beneficial effects of the present invention are: a) The present invention can obtain large-sized two-dimensional black phosphorus nanosheets through electrochemical dissociation of black phosphorus single crystal technology. Electrochemical dissociation can quickly drive cations in the electrolyte into the black phosphorus interlayer. The cations decompose under negative potential, thereby destroying the van der Waals force between the black phosphorus layers, achieving the purpose of stripping black phosphorus, and then obtaining a large number of two-dimensional black phosphorus nanosheets.

[0016] 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 evenly, which is conducive to the preparation of a large number of black phosphorus nanosheets and silver nanowire heterojunctions.

[0017] c) The black phosphorus nanosheet and silver nanowire heterojunction prepared by the present invention can completely expose the active sites of the black phosphorus nanosheet, effectively enhance the electron transfer between the black phosphorus and the silver nanowire, and has the advantages of large-scale production and significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is the XRD pattern of black phosphorus crystal; Figure 2 Raman image of two-dimensional black phosphorus nanosheets; Figure 3 TEM image of two-dimensional black phosphorus nanosheets; Figure 4 AFM image of two-dimensional black phosphorus nanosheets; Figure 5 TEM image of silver nanowires; Figure 6 a is the TEM image of the heterojunction of black phosphorus and silver nanowires; Figure 6 b is a high-angle annular dark field image of a black phosphorus and silver nanowire heterojunction; Figure 6 c, 6d are EDS images of black phosphorus and silver nanowire heterojunctions; Figure 7 Impedance diagram of supercapacitors based on black phosphorus and black phosphorus and silver nanowire heterojunctions. DETAILED DESCRIPTION

[0019] In order to understand the present invention more clearly, the present invention is further described with reference to the following examples and accompanying drawings. The examples are only used for explanation and are not intended to limit the present invention in any way. In the examples, each raw material reagent is commercially available, and the experimental methods without specifying specific conditions are conventional methods and conventional conditions well known in the art, or according to the conditions recommended by the instrument manufacturer. Example 1

[0020] This embodiment provides a method for preparing a black phosphorus and silver nanowire heterojunction composite material, comprising the following steps: (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, electrochemically dissociating for 10 minutes, and then vacuum filtering, washing and vacuum drying (100°C) to obtain large-sized two-dimensional black phosphorus nanosheets.

[0021] Figure 1 This is the XRD pattern of the large-sized two-dimensional black phosphorus nanosheets. By comparing with the standard PDF card, it can be seen that high-purity black phosphorus nanosheets have been successfully obtained. Figure 2 This is the Raman image of the two-dimensional black phosphorus nanosheet. The three peaks in the image 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, which shows that the thickness of the two-dimensional black phosphorus nanosheet is 4-8 nanometers.

[0022] (2) The large-sized two-dimensional black phosphorus nanosheets obtained in step (1) are 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.

[0023] (3) Centrifuging the two-dimensional black phosphorus nanosheet dispersion obtained in step (2) at a centrifugal speed of 1000 rpm, extracting the supernatant after centrifugation for 1 hour to obtain ultrathin two-dimensional black phosphorus nanosheets, and then vacuum filtering, washing and vacuum drying (100° C.) to obtain two-dimensional black phosphorus nanosheets.

[0024] (4) The two-dimensional black phosphorus nanosheets obtained in step (3) and silver nanowires (length range: 5-50 μm, diameter range: 30-100 nm) are 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 is obtained.

[0025] Figure 5 This is a TEM image of silver nanowires. The length of the silver nanowires can reach the micron level. 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, and the phosphorus and silver elements are evenly distributed in the black phosphorus and silver nanowire heterojunction.

[0026] Figure 7 The impedance diagram of supercapacitors based on black phosphorus, black phosphorus and silver nanowire heterojunctions. In the entire frequency range, the slope of the supercapacitor impedance spectrum of the black phosphorus and silver nanowire heterojunctions is higher than that of the black phosphorus supercapacitor in the low-frequency stage, and the imaginary part increases rapidly, approaching 90°, indicating that the ion migration speed of the black phosphorus and silver nanowire heterojunctions is higher than that of the black phosphorus device. In the high-frequency stage, the results show that the device resistance of the black phosphorus and silver nanowire heterojunctions is lower than that of the black phosphorus device. Therefore, the black phosphorus and silver nanowire heterojunction structure can effectively expose the active sites in the black phosphorus nanosheets, enhance their ion migration rate and reduce the device resistance, so that it exhibits better energy storage performance. Example 2

[0027] This embodiment provides a method for preparing a black phosphorus and silver nanowire heterojunction composite material, comprising the following steps: (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.

[0028] (2) The large-sized two-dimensional black phosphorus nanosheets obtained in step (1) are 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.

[0029] (3) Centrifuging the two-dimensional black phosphorus nanosheet dispersion obtained in step (2) at a centrifugal speed of 2000 rpm, extracting the supernatant after centrifugation for 2 hours to obtain ultrathin two-dimensional black phosphorus nanosheets, and then vacuum filtering, washing and vacuum drying (80° C.) to obtain two-dimensional black phosphorus nanosheets.

[0030] (4) The two-dimensional black phosphorus nanosheets obtained in step (3) and silver nanowires (length range: 5-50 μm, diameter range: 30-100 nm) are ultrasonically dispersed (ultrasonic power of 300 W, time of 60 minutes) in a solution at a mass ratio of 1:2, and allowed to stand for 3 hours to allow self-assembly, and then vacuum filtered, washed and vacuum dried (80°C) to obtain a heterojunction of black phosphorus and silver nanowires. Example 3

[0031] This embodiment provides a method for preparing a black phosphorus and silver nanowire heterojunction composite material, comprising the following steps: (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, and then vacuum filtering, washing and vacuum drying (100°C) to obtain large-sized two-dimensional black phosphorus nanosheets.

[0032] (2) The large-sized two-dimensional black phosphorus nanosheets obtained in step (1) are 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.

[0033] (3) Centrifuging the two-dimensional black phosphorus nanosheet dispersion obtained in step (2) at a centrifugal speed of 5000 rpm, extracting the supernatant after centrifugation for 1 hour to obtain ultrathin two-dimensional black phosphorus nanosheets, and then vacuum filtering, washing and vacuum drying (100° C.) to obtain two-dimensional black phosphorus nanosheets.

[0034] (4) The two-dimensional black phosphorus nanosheets obtained in step (3) and silver nanowires (length range: 5-50 μm, diameter range: 30-100 nm) are ultrasonically dispersed (ultrasonic power of 500 W, time of 30 minutes) in a solution at a mass ratio of 1:4, and allowed to stand for 5 hours to allow self-assembly, and then vacuum filtered, washed and vacuum dried (100°C) to obtain a heterojunction of black phosphorus and silver nanowires. Example 4

[0035] This embodiment provides a method for preparing a black phosphorus and silver nanowire heterojunction composite material, comprising the following steps: (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, and then vacuum filtering, washing and vacuum drying (100°C) to obtain large-sized two-dimensional black phosphorus nanosheets.

[0036] (2) The large-sized two-dimensional black phosphorus nanosheets obtained in step (1) are 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.

[0037] (3) Centrifuging the two-dimensional black phosphorus nanosheet dispersion obtained in step (2) at a centrifugal speed of 2000 rpm, extracting the supernatant after centrifugation for 1 hour to obtain ultrathin two-dimensional black phosphorus nanosheets, and then vacuum filtering, washing and vacuum drying (100° C.) to obtain two-dimensional black phosphorus nanosheets.

[0038] (4) The two-dimensional black phosphorus nanosheets obtained in step (3) and silver nanowires (length range: 5-50 μm, diameter range: 30-100 nm) are 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, and then vacuum filtered, washed and vacuum dried (100°C) to obtain a heterojunction of black phosphorus and silver nanowires. Example 5

[0039] This embodiment provides a method for preparing a black phosphorus and silver nanowire heterojunction composite material, comprising the following steps: (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, and then vacuum filtering, washing and vacuum drying (100°C) to obtain large-sized two-dimensional black phosphorus nanosheets.

[0040] (2) The large-sized two-dimensional black phosphorus nanosheets obtained in step (1) are 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.

[0041] (3) Centrifuging the two-dimensional black phosphorus nanosheet dispersion obtained in step (2) at a centrifugal speed of 5000 rpm, extracting the supernatant after centrifugation for 2 hours to obtain ultrathin two-dimensional black phosphorus nanosheets, and then vacuum filtering, washing and vacuum drying (100° C.) to obtain two-dimensional black phosphorus nanosheets.

[0042] (4) The two-dimensional black phosphorus nanosheets obtained in step (3) and silver nanowires (length range: 5-50 μm, diameter range: 30-100 nm) are 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, and then vacuum filtered, washed and vacuum dried (100° C.) to obtain a heterojunction of black phosphorus and silver nanowires.

[0043] The embodiments described above are only descriptions of the preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design 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 all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a black phosphorus and silver nanowire heterojunction composite material, characterized in that it comprises the following steps: (1) Placing a black phosphorus single crystal in a dimethyl sulfoxide solution containing tetrabutylammonium bromide, with black phosphorus as the negative electrode and a platinum electrode as the positive electrode, electrochemically dissociates the black phosphorus, and then obtains large-sized two-dimensional black phosphorus nanosheets after vacuum filtration, washing and vacuum drying; (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) The two-dimensional black phosphorus nanosheets and silver nanowires obtained in step (3) are ultrasonically dispersed in a solution and allowed to stand to allow them to self-assemble. After vacuum filtration, washing and vacuum drying, a heterojunction of black phosphorus and silver nanowires is obtained.

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

5. The preparation method according to claim 1, characterized in that 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, characterized in that: In step (4), the mass ratio of the two-dimensional black phosphorus nanosheets to the silver nanowires is 1:(1-10); Preferably, the silver nanowire has a length of 5-50 μm and a diameter of 30-100 nm.

7. The preparation method according to claim 1, characterized in that In step (4), the power of the ultrasonic dispersion 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 static 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.

Images