Preparation method of piezoelectric nanogenerator with all-weather service capability based on N-doped SiC nanostructure array

Abstract

The present invention provides a method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array, which belongs to the field of inorganic non-metallic material science and energy material technology, and the steps include: preparing N-doped silicon carbide, preparing a self-supporting silicon carbide nanostructure array film, optimizing the performance of the silicon carbide nanostructure array film, and constructing a piezoelectric nanogenerator with all-weather service capability. The method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array provided by the present invention, when the prepared piezoelectric nanogenerator is subjected to an external force along the thickness direction, it exhibits significant electrical signal output in the macroscopic sense. Moreover, the prepared piezoelectric nanogenerator can still maintain stable output after working for 300-500 days under the conditions of a temperature of ‑80°C to 80°C and a relative humidity of 0-100%.

Description

Technical Field

[0001] The present invention relates to the field of inorganic non-metallic science and energy material technology, and in particular to a method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array. Background Art

[0002] At present, piezoelectric nanogenerators have attracted widespread attention due to their ability to effectively convert disordered mechanical energy in the natural environment into electrical energy. Globally, the earth's environment is highly complex and has great differences. In terms of temperature, the temperature in low-temperature areas can be as low as -70°C, while the temperature in high-temperature areas can be as high as 60°C. In terms of relative humidity, the relative humidity in desert areas is 0%, while the relative humidity in tropical rainforest areas is close to 100%. Therefore, it is very important and urgent to develop piezoelectric nanogenerators that can provide all-weather service capabilities worldwide.

[0003] At present, many materials can be used to assemble piezoelectric nanogenerators, but they have a series of problems as follows: (1) When zinc oxide is used to assemble piezoelectric nanogenerators, the chemical instability of zinc oxide limits the application of the piezoelectric nanogenerators assembled from it in acidic and alkaline environments; (2) When piezoelectric polymers such as PVDF, P(VDF-TrFE) and PVDF-HFP are used in piezoelectric nanogenerators, the ferroelectric phase of these piezoelectric polymers is unstable in high temperature environments, resulting in the piezoelectric nanogenerators assembled from them cannot be used in extreme temperature environments; (3) Traditional piezoelectric ceramic materials usually contain heavy metal lead, and the piezoelectric nanogenerators assembled from them are often harmful to the human body and the environment. The preparation process of lead-free piezoelectric ceramic materials is complex, the synthesis conditions are harsh, and the preparation cost is high, which is not suitable for promotion in practical applications. In addition, the high brittleness of piezoelectric ceramic materials makes the piezoelectric nanogenerators assembled from them easy to damage, which seriously limits their service life. Summary of the invention

[0004] In view of the above problems existing in assembling piezoelectric nanogenerators with existing materials, the present invention provides a method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array.

[0005] Silicon carbide is one of the most important third-generation semiconductor materials. It has excellent chemical and thermal stability, outstanding mechanical properties and good thermal shock resistance. It is considered to be one of the potential materials for building devices with excellent stability and durability, especially it can be used under harsh conditions such as high temperature, high pressure, high radiation and high power. Since silicon carbide also has a significant piezoelectric effect, the present invention proposes a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array to solve the problems existing in the assembly of piezoelectric nanogenerators with existing materials.

[0006] In order to solve the above technical problems, the present invention provides a method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array, comprising the following steps:

[0007] Preparation of N-doped silicon carbide: using N2O5 as a nitrogen source, nitrogen-doping a silicon carbide single crystal wafer for 1-20 hours at a temperature of 1000-1500°C, a pressure of 100-500 Pa, and an argon atmosphere to obtain silicon carbide with a nitrogen doping concentration of 0.1-10 mol%;

[0008] Preparation of self-supporting silicon carbide nanostructure array film: electrochemically etching the carbon surface or silicon surface of N-doped silicon carbide to form a silicon carbide nanostructure array film with a thickness of 50-300 μm and a morphology of nanopores, nanobelts, nanorods or nanowires;

[0009] Optimization of silicon carbide nanostructure array film performance: including,

[0010] In an air or oxygen atmosphere, the silicon carbide forming the silicon carbide nanostructure array film is kept at a temperature of 1300-1800° C. for 1-24 hours to form a SiO2 oxide layer on the surface of the silicon carbide;

[0011] The polymer dispersed with the conductive filler is coated on the silicon carbide nanostructure array film of the silicon carbide with the SiO2 oxide layer formed on the surface, and after drying, a conductive filler polymer coating layer with a thickness of 100-500 μm is formed;

[0012] Using plasma to clean the polymer on the silicon carbide nanostructure array film until the nanostructure array is exposed by 10-50 μm;

[0013] Spin coating a layer of polymer without conductive filler on the silicon carbide nanostructure array film, and drying to form a polymer layer without conductive filler with a thickness of 20-80 μm;

[0014] Construct a piezoelectric nanogenerator with all-weather service capability: magnetron sputter a layer of metal with a thickness of 10-100nm on both sides of silicon carbide as the upper and lower electrodes, lead out the wires and package the entire device on a substrate to obtain a piezoelectric nanogenerator with all-weather service capability.

[0015] Furthermore, the silicon carbide single crystal wafer is a single-sided or double-sided polished silicon carbide single crystal wafer with a thickness of 100-500 μm and a crystal type of 2H, 4H or 6H.

[0016] Furthermore, the electrochemical etching uses a power supply with a direct current or pulse voltage of 5-50V and a direct current or pulse current of 100-500 mA, the pulse waveform is a sine wave, a triangle wave or a rectangular wave, and the pulse duty ratio is 10-90%.

[0017] Furthermore, the amount of etching solution used in the electrochemical etching is 10-50 ml, and the etching time is 1-100 min.

[0018] Furthermore, the etching solution is a mixture of hydrofluoric acid, ethanol and hydrogen peroxide, and the mass ratio of the hydrofluoric acid, ethanol and hydrogen peroxide is (1-20): (1-20): (0-10).

[0019] Furthermore, the conductive filler is MXene, graphene, carbon black or metal powder, and the morphology of the conductive filler is nanoparticles, nanowires, nanorods, nanotubes, nanobelts or nanosheets.

[0020] Furthermore, the polymer is PDMS, PMMA or epoxy resin.

[0021] Furthermore, the polymer is dried at a temperature of 60-100° C. for 30-300 min.

[0022] Furthermore, the metal magnetron sputtered on both sides of silicon carbide is copper, aluminum, silver, gold or / and platinum, and the substrate is PE, PET, PP, PS or PVC.

[0023] Furthermore, the piezoelectric nanogenerator can stably output for 300-500 days under the conditions of a temperature of -80°C to 80°C and a relative humidity of 0-100%.

[0024] The method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array provided by the present invention firstly performs N-doping on a silicon carbide single crystal wafer, which not only improves the asymmetry of the silicon carbide crystal structure and enhances its piezoelectric response capability, but also increases the carrier concentration of silicon carbide, improves its conductivity, and makes subsequent electrochemical etching easier to complete. Then, after the N-doped silicon carbide is electrochemically etched, a uniform and dense silicon dioxide film is formed on the surface of the silicon carbide, which not only ensures that the mechanical stability of the silicon carbide nanostructure array film formed on the N-doped silicon carbide after electrochemical etching is not destroyed, but also improves the oxidation resistance of the silicon carbide nanostructure array film. Then, by introducing polymers and conductive fillers on the silicon carbide nanostructure array film, the durability and current transmission capability of the device can be improved at the same time, and its output performance is effectively optimized. Finally, the device structure is completely encapsulated, which not only improves the service stability of the prepared piezoelectric nanogenerator, but also isolates the damage of the piezoelectric nanogenerator to the external pollution.

[0025] The invention provides a method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array. When the prepared piezoelectric nanogenerator is subjected to external forces such as low-frequency human body movements such as finger pressing, elbow bending or / and foot pedaling, and irregular machine vibrations such as cantilever beam swinging or / and automobile exhaust pipe vibration, due to the positive piezoelectric effect, a dipole with highly consistent polarization direction will be generated inside the single-crystal silicon carbide, showing significant electrical signal output in the macroscopic sense. Moreover, the prepared piezoelectric nanogenerator can still maintain stable output after working for 300-500 days under the conditions of -80℃ to 80℃ and 0-100% relative humidity, showing an extremely wide temperature and relative humidity working range and excellent long-term service stability, providing new opportunities for the global application of self-powered systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A flow chart of a method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array provided in an embodiment of the present invention;

[0027] Figure 2 A schematic diagram of forming a silicon carbide nanostructure array film from N-doped silicon carbide in a method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array provided in an embodiment of the present invention;

[0028] Figure 3 A schematic diagram of forming a SiO2 oxide layer on the surface of an N-doped silicon carbide film forming a silicon carbide nanostructure array in a method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array provided in an embodiment of the present invention;

[0029] Figure 4 A schematic diagram of forming a polymer coating layer containing a conductive filler on a silicon carbide nanostructure array film having a SiO2 oxide layer formed on the surface in a method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array provided in an embodiment of the present invention;

[0030] Figure 5 A schematic diagram of forming a polymer coating layer without conductive fillers on a silicon carbide nanostructure array film having a SiO2 oxide layer formed on the surface in a method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array provided in an embodiment of the present invention;

[0031] Figure 6The output current density diagram of the piezoelectric nanogenerator when pressed by a finger, which is obtained by the method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array provided in an embodiment of the present invention;

[0032] Figure 7 The output current density diagram of the piezoelectric nanogenerator when pedaling, which is prepared by the method for preparing the piezoelectric nanogenerator with all-weather service capability based on the N-doped SiC nanostructure array provided in the embodiment of the present invention;

[0033] Figure 8 The output current density diagram of the piezoelectric nanogenerator when the cantilever beam is swinging, which is obtained by the method for preparing the piezoelectric nanogenerator with all-weather service capability based on the N-doped SiC nanostructure array provided in the embodiment of the present invention;

[0034] Fig. 9 The output current density diagram of the piezoelectric nanogenerator when the hair dryer vibrates, which is obtained by the method for preparing the piezoelectric nanogenerator with all-weather service capability based on the N-doped SiC nanostructure array provided in the embodiment of the present invention;

[0035] Fig.10 The output current density diagram of the piezoelectric nanogenerator at a temperature of -80°C prepared by the method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array provided in an embodiment of the present invention;

[0036] Fig.11 The output current density diagram of the piezoelectric nanogenerator at a temperature of 80° C. prepared by the method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array provided in an embodiment of the present invention;

[0037] Fig.12 An output current density diagram of a piezoelectric nanogenerator at a relative humidity of 0% obtained by a method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array provided in an embodiment of the present invention;

[0038] Fig.13 An output current density diagram of a piezoelectric nanogenerator at a relative humidity of 100% obtained by a method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0039] See also Figure 1The present invention provides a method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array, comprising the following steps:

[0040] Step 1) Preparation of N-doped silicon carbide: Using N2O5 as a nitrogen source, nitrogen-doping a silicon carbide single crystal wafer for 1-20 hours at a temperature of 1000-1500°C, a pressure of 100-500Pa, and an argon atmosphere to obtain silicon carbide with a nitrogen doping concentration of 0.1-10 mol%. The silicon carbide single crystal wafer is a single-sided or double-sided polished silicon carbide single crystal wafer with a thickness of 100-500μm and a crystal form of 2H, 4H or 6H. By single nitrogen doping of the silicon carbide single crystal wafer, on the one hand, the asymmetry of the silicon carbide crystal structure can be improved, its piezoelectric coefficient can be improved, and its piezoelectric response ability can be enhanced; on the other hand, the introduction of N atoms increases the carrier concentration of silicon carbide, thereby improving its conductivity, making it easier to complete the electrochemical etching of silicon carbide in the next step.

[0041] Step 2) Preparation of self-supporting silicon carbide nanostructure array film: electrochemically etch the carbon surface or silicon surface of N-doped silicon carbide to form a silicon carbide nanostructure array film with a thickness of 50-300 μm and a morphology of nanopores, nanobelts, nanorods or nanowires on the N-doped silicon carbide. The electrochemical etching uses a power supply with a direct current or pulse voltage of 5-50V and a direct current or pulse current of 100-500mA, and the pulse waveform is a sine wave, a triangular wave or a rectangular wave, and the pulse duty cycle is 10-90%. The etching solution used in the electrochemical etching is a mixture of hydrofluoric acid, ethanol and hydrogen peroxide, and the mass ratio of hydrofluoric acid, ethanol and hydrogen peroxide in the etching solution is (1-20): (1-20): (0-10). The amount of etching solution used in the electrochemical etching is 10-50ml, and the etching time is 1-100min. During the actual service of the device, when subjected to the same external force, array films with morphologies such as nanowires, nanorods and nanobelts can produce larger deformations, which manifests as greater electrical energy output, and are suitable for occasions with higher requirements for output peaks; while array films with nanopore morphologies have smaller deformations. These small deformations make the array films have better structural stability, thereby increasing their service life, and are suitable for work environments with harsh working environments and requiring long-term stable service. Therefore, during electrochemical etching, by adjusting the type and waveform of the power supply, the composition and amount of the etching solution, and the etching time and object, a self-supporting silicon carbide nanostructure array film with the expected morphology and expected thickness can be obtained, so that the final piezoelectric nanogenerator can adapt to different service environments. The silicon carbide nanostructure array film formed on N-doped silicon carbide, such as Figure 2 shown.

[0042] Step 3) optimizing the performance of the silicon carbide nanostructure array film, the process includes:

[0043] First, in an air or oxygen atmosphere, the silicon carbide forming the silicon carbide nanostructure array film is kept at a temperature of 1300-1800°C for 1-24 hours to form a uniform and dense SiO2 oxide layer on the surface of the silicon carbide. Figure 3 A uniform and dense SiO2 oxide layer is formed on the surface of silicon carbide, which can not only improve the oxidation resistance of silicon carbide, but also ensure the tightness of the interface connection between the silicon carbide nanostructure array film and the N-doped silicon carbide, so that the stability of the interface connection structure is not destroyed.

[0044] Then, a layer of polymer with conductive fillers evenly dispersed is coated on the silicon carbide nanostructure array film with SiC formed on the surface of the SiC nanostructure array film (i.e., the side of the silicon carbide nanostructure array film without a cap layer described in the subsequent embodiments), so that the polymer containing the conductive fillers is evenly coated on the silicon carbide nanostructure array film, and the polymer containing the conductive fillers fills the gaps between the silicon carbide nanostructure arrays. Then, the silicon carbide is kept at a temperature of 60-100°C for 30-300 minutes, and the polymer containing the conductive fillers is dried, thereby forming a layer of conductive filler-containing polymer coating layer with a thickness of 100-500μm on the silicon carbide nanostructure array film. In this way, the infiltration of the conductive filler-containing polymer on the silicon carbide nanostructure array film can greatly improve the mechanical stability and durability of the silicon carbide nanostructure array film, and the conductive fillers that are in contact or close to each other can effectively optimize the conduction of piezoelectric current. After the silicon carbide nanostructure array film is coated with a polymer coating layer containing conductive fillers, as shown in FIG. Figure 4 As shown. The polymer is PDMS, PMMA or epoxy resin. The conductive filler is MXene, graphene, carbon black or metal powder. Since the morphology of the conductive filler can be nanoparticles, nanowires, nanorods, nanotubes, nanobelts or nanosheets, the conductive filler matching the morphology can be selected in a targeted manner according to the morphology of the silicon carbide nanostructure array film etched on the silicon carbide. For example, for the silicon carbide nanostructure array film with a smaller gap, a conductive filler with a morphology of nanoparticles with a smaller diameter can be selected. For the silicon carbide nanostructure array film with a morphology of nanowires and nanobelts with a larger gap, a conductive filler with a morphology of nanorods or nanotubes can be selected.

[0045] Subsequently, the polymer on the silicon carbide nanostructure array film is cleaned by plasma until the nanostructure array is exposed by 10-50 μm.

[0046] Finally, a layer of polymer without conductive filler is spin-coated on the exposed silicon carbide nanostructure array film, and after drying, a polymer layer without conductive filler having a thickness of 20-80 μm is formed. Figure 5 shown.

[0047] Step 4) Constructing a piezoelectric nanogenerator with all-weather service capability: magnetron sputtering a layer of metal with a thickness of 10-100nm on both sides of silicon carbide as upper and lower electrodes, and encapsulating the entire device on a substrate with a polymer after leading out the wires, thus obtaining a piezoelectric nanogenerator with all-weather service capability. The metal magnetron sputtered on both sides of silicon carbide is copper, aluminum, silver, gold or platinum, and the substrate is PE, PET, PP, PS or PVC. Complete encapsulation can not only increase the service stability of the device, but also isolate the damage of external pollution to the piezoelectric nanogenerator.

[0048] When the piezoelectric nanogenerator prepared by the present invention is subjected to low-frequency human body movements such as finger pressing, elbow bending and / or foot pedaling in the thickness direction, or to irregular machine vibrations such as cantilever beam swinging and / or automobile exhaust pipe vibration, according to the positive piezoelectric effect, a dipole with highly consistent polarization direction will be generated inside the single-crystal silicon carbide, and significant electrical signal output will be shown macroscopically. The piezoelectric nanogenerator is placed at a temperature of -80-80°C and a relative humidity of 0-100% for 300-500 days, and the piezoelectric nanogenerator can still maintain stable output, showing an extremely wide temperature and relative humidity working range and excellent long-term service stability.

[0049] The following is a specific example of a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array provided by the present invention.

[0050] Embodiment 1:

[0051] (1) Preparation of N-doped silicon carbide single crystal wafer: This embodiment uses a single-side polished silicon carbide single crystal wafer with a crystal form of 2H as the raw material, and its thickness is 100 μm. With N2O5 as the nitrogen source, the silicon carbide single crystal wafer is nitrogen-doped for 1 hour at 1000°C, 100 Pa pressure, and argon atmosphere protection to obtain silicon carbide with a nitrogen doping concentration of 0.1 mol%.

[0052] (2) Preparation of self-supporting silicon carbide nanostructure array film: Based on N-doped silicon carbide single crystal, the carbon surface of the N-doped silicon carbide single crystal is etched by electrochemical etching. The etching adopts a pulse voltage (5V) and a pulse current (100mA) power supply; the pulse waveform is a sine wave, and the pulse duty cycle is 10%; the ratio of hydrofluoric acid, ethanol and hydrogen peroxide in the etching solution can be 8:5:0, and the amount is 10ml; etching for 1min, and finally a silicon carbide nanostructure array film with a nanoporous morphology and a thickness of 50μm is obtained by the face-changing peeling method.

[0053] (3) Performance optimization of silicon carbide nanostructure array film: First, the silicon carbide nanoarray film is kept at 1300°C for 1 hour in an atmosphere of air or oxygen to form a uniform and dense SiO2 oxide layer on its surface. Then, nano-particle-shaped carbon black is evenly dispersed in the organic polymer PDMS as a conductive filler, and the polymer containing the conductive filler is evenly coated on the side of the uncapped layer of the silicon carbide film to ensure that the array gaps are filled. The polymer coating thickness is 100μm, and it is kept at 60°C for 30 minutes and dried. Subsequently, the polymer on the uncapped layer of the silicon carbide nanoarray film is cleaned by plasma until 10μm of the nanostructure array is exposed, and finally a layer of polymer without conductive filler with a thickness of 20μm is spin-coated on the exposed nanostructure array.

[0054] (4) Construction of a piezoelectric nanogenerator with all-weather service capability: Based on the third step, a layer of gold-platinum alloy with a thickness of 10 nm is magnetron sputtered on both surfaces of silicon carbide as the upper and lower electrodes. After the two electrodes are led out, the entire device is completely encapsulated with a polymer on a PET substrate to obtain a piezoelectric nanogenerator.

[0055] (5) Service of the piezoelectric nanogenerator: Press the piezoelectric nanogenerator along the thickness direction with your finger. According to the positive piezoelectric effect, a dipole with highly consistent polarization direction is generated inside the single crystal silicon carbide, which shows a significant electrical signal output on a macro scale. The output current density of the piezoelectric nanogenerator prepared in the embodiment of the present invention when pressed by a finger is as follows: Figure 6 As shown, Figure 6 It can be shown that the piezoelectric nanogenerator prepared by the embodiment of the present invention has a strong ability to collect and convert low-frequency mechanical energy generated by the movement of objects in nature. The piezoelectric nanogenerator was placed in a temperature condition of -80°C and a relative humidity condition of 0% and operated for 300 days. The piezoelectric nanogenerator still maintained a stable output, showing an extremely wide temperature and relative humidity operating range and excellent long-term service stability. The output current density of the piezoelectric nanogenerator prepared by the embodiment of the present invention when working in an environment with a temperature of -80°C is as follows: Fig.10 As shown, the output current density of the piezoelectric nanogenerator prepared in the embodiment of the present invention when working in an environment with a relative humidity of 0% is as follows Fig.12 shown. Fig.10 and Fig.12 It can be explained that the piezoelectric nanogenerator prepared in the embodiment of the present invention can still maintain a high output in an extreme environment of a temperature of -80°C and a relative humidity of 0%, fully demonstrating its stability against temperature and humidity, indicating that it can be fully applied in all-weather service environments around the world.

[0056] Embodiment 2:

[0057] (1) Preparation of N-doped silicon carbide single crystal wafer: In this embodiment, a 4H double-sided polished silicon carbide single crystal wafer with a thickness of 300 μm is selected as the raw material. With N2O5 as the nitrogen source, the silicon carbide single crystal wafer is nitrogen-doped for 10 hours at 1300°C, 300 Pa pressure, and argon atmosphere protection to obtain silicon carbide with a nitrogen doping concentration of 5 mol%.

[0058] (2) Preparation of self-supporting silicon carbide nanostructure array film: Based on N-doped silicon carbide single crystal, the carbon surface of the N-doped silicon carbide single crystal is etched by electrochemical etching. Etching uses a power supply of DC voltage (25V) and DC current (250mA); the pulse waveform is a triangle wave, and the pulse duty cycle is 50%; the ratio of hydrofluoric acid, ethanol and hydrogen peroxide in the etching solution can be 10:10:7, and the amount is 30ml; etching for 50min, and finally a silicon carbide nanostructure array film with a nanobelt morphology and a thickness of 200μm is obtained by the face-changing peeling method.

[0059] (3) Performance optimization of silicon carbide nanostructure array film: First, the silicon carbide nanoarray film is kept at 1500°C for 12 hours in an atmosphere of air or oxygen to form a uniform and dense SiO2 oxide layer on its surface. Then, the nanoscale MXene with the morphology of nanobelts is evenly dispersed in the organic polymer PMMA as a conductive filler, and the polymer containing the conductive filler is evenly coated on the side of the uncapped layer of the silicon carbide film to ensure that the array gaps are filled. The polymer coating thickness is 300μm, and it is kept at 80°C for 150min and dried. Subsequently, the polymer on the uncapped layer of the silicon carbide nanoarray film is cleaned by plasma until the nanostructure array is exposed by 30μm, and finally a layer of polymer without conductive filler with a thickness of 50μm is spin-coated on the exposed nanostructure array.

[0060] (4) Construction of a piezoelectric nanogenerator with all-weather service capability: Based on the third step, a layer of gold-silver alloy with a thickness of 50 nm is magnetron sputtered on the two surfaces of silicon carbide as the upper and lower electrodes. After the two electrodes are led out, the entire device is completely encapsulated with a polymer on a PVC substrate to obtain a piezoelectric nanogenerator.

[0061] (5) Service of the piezoelectric nanogenerator: The piezoelectric nanogenerator is pressed along the thickness direction by pedaling. According to the positive piezoelectric effect, a dipole with highly consistent polarization direction is generated inside the single crystal silicon carbide, and a significant electrical signal output is shown on a macroscopic scale. The output current density of the piezoelectric nanogenerator prepared in the embodiment of the present invention when pedaling is as follows: Figure 7 As shown, Figure 7It can be shown that the piezoelectric nanogenerator prepared by the embodiment of the present invention has a strong ability to collect and convert low-frequency mechanical energy generated by the movement of objects in nature. The piezoelectric nanogenerator was placed in a temperature condition of 80°C and a relative humidity condition of 0% and operated for 500 days. The piezoelectric nanogenerator still maintained a stable output, showing an extremely wide temperature and relative humidity operating range and excellent long-term service stability. The output current density of the piezoelectric nanogenerator prepared by the embodiment of the present invention when working in an environment with a temperature of 80°C is as follows: Fig.11 As shown, the output current density of the piezoelectric nanogenerator prepared in the embodiment of the present invention when working in an environment with a relative humidity of 0% is as follows Fig.12 As shown. Fig.11 and Fig.12 It can be explained that the piezoelectric nanogenerator prepared in the embodiment of the present invention can still maintain a high output in an extreme environment of a temperature of 80°C and a relative humidity of 0%, fully demonstrating its stability against temperature and humidity, indicating that it can be fully applied in all-weather service environments around the world.

[0062] Embodiment 3:

[0063] (1) Preparation of N-doped silicon carbide single crystal wafer: In this embodiment, a 6H double-sided polished silicon carbide single crystal wafer with a thickness of 500 μm is selected as the raw material. With N2O5 as the nitrogen source, the silicon carbide single crystal wafer is nitrogen-doped for 20 hours at 1500°C, 500 Pa pressure, and argon atmosphere protection to obtain silicon carbide with a nitrogen doping concentration of 10 mol%.

[0064] (2) Preparation of self-supporting silicon carbide nanostructure array film: Based on an N-doped silicon carbide single crystal, the silicon surface of the N-doped silicon carbide single crystal is etched by electrochemical etching. The etching uses a power supply of DC voltage (50V) and DC current (500mA); the pulse waveform is a rectangular wave, and the pulse duty cycle is 90%; the ratio of hydrofluoric acid, ethanol and hydrogen peroxide in the etching solution can be 20:3:1, and the amount is 50ml; the etching time is 100min, and finally a silicon carbide nanostructure array film with a morphology of nanowires and a thickness of 300μm is obtained by the face-changing peeling method.

[0065] (3) Performance optimization of silicon carbide nanostructure array film: First, the silicon carbide nanoarray film is kept at 1800°C for 24 hours in an atmosphere of air or oxygen to form a uniform and dense SiO2 oxide layer on its surface. Then, nanoscale metal powder with the morphology of nanowires is evenly dispersed in an organic polymer epoxy resin as a conductive filler, and the polymer containing the conductive filler is evenly coated on the side of the uncapped layer of the silicon carbide film to ensure that the array gaps are filled. The polymer coating thickness is 500 μm, and the film is kept at 100°C for 300 minutes and dried. Subsequently, the polymer on the uncapped layer of the silicon carbide nanoarray film is cleaned by plasma until 50 μm of the nanostructure array is exposed, and finally a layer of polymer without conductive filler with a thickness of 80 μm is spin-coated on the exposed nanostructure array.

[0066] (4) Construction of a piezoelectric nanogenerator with all-weather service capability: Based on the third step, a layer of gold-silver-copper alloy with a thickness of 100 nm is magnetron sputtered on both surfaces of silicon carbide as the upper and lower electrodes. After the two electrodes are led out, the entire device is completely encapsulated with a polymer on a PS substrate to obtain a piezoelectric nanogenerator.

[0067] (5) Service of the piezoelectric nanogenerator: The piezoelectric nanogenerator is vibrated along the thickness direction by swinging the cantilever beam. According to the positive piezoelectric effect, a dipole with highly consistent polarization direction is generated inside the single crystal silicon carbide, and a significant electrical signal output is shown in the macroscopic view. The output current density of the piezoelectric nanogenerator prepared in the embodiment of the present invention when the cantilever beam is swinging is as follows: Figure 8 As shown, Figure 8 It can be shown that the piezoelectric nanogenerator prepared by the embodiment of the present invention has a strong ability to collect and convert low-frequency mechanical energy generated by the movement of objects in nature. The piezoelectric nanogenerator was placed in a temperature condition of -80°C and a relative humidity condition of 100% and operated for 500 days. The piezoelectric nanogenerator still maintained a stable output, showing an extremely wide temperature and relative humidity operating range and excellent long-term service stability. The output current density of the piezoelectric nanogenerator prepared by the embodiment of the present invention when working in an environment with a temperature of -80°C is as follows: Fig.10 As shown, the output current density of the piezoelectric nanogenerator prepared in the embodiment of the present invention when working in an environment with a relative humidity of 100% is as follows Fig.13 As shown. Fig.10 and Fig.13 It can be explained that the piezoelectric nanogenerator prepared in the embodiment of the present invention can still maintain a high output in an extreme environment of a temperature of -80°C and a relative humidity of 100%, fully demonstrating its stability against temperature and humidity, indicating that it can be fully applied in all-weather service environments around the world.

[0068] Embodiment 4:

[0069] (1) Preparation of N-doped silicon carbide single crystal wafer: This embodiment uses a single-side polished silicon carbide single crystal wafer with a crystal form of 4H as the raw material, and its thickness is 400 μm. With N2O5 as the nitrogen source, the silicon carbide single crystal wafer is nitrogen-doped for 15 hours at 1400°C, 400 Pa pressure, and argon atmosphere protection to obtain silicon carbide with a nitrogen doping concentration of 50 mol%.

[0070] (2) Preparation of self-supporting silicon carbide nanostructure array film: Based on an N-doped silicon carbide single crystal, the silicon surface of the N-doped silicon carbide single crystal is etched by electrochemical etching. The etching adopts a pulse voltage (40V) and a pulse current (400mA) power supply; the pulse waveform is a sine wave, and the pulse duty cycle is 50%; the ratio of hydrofluoric acid, ethanol and hydrogen peroxide in the etching solution can be 20:10:5, and the amount is 40ml; the etching is 60min, and finally a silicon carbide nanostructure array film with a nanorod morphology and a thickness of 200μm is obtained by the face-changing peeling method.

[0071] (3) Performance optimization of silicon carbide nanostructure array film: First, the silicon carbide nanostructure array film is kept at 1500℃ for 20 hours in an atmosphere of air or oxygen to form a uniform and dense SiO2 oxide layer on its surface. Then, nanoscale graphene with the morphology of nanorods is evenly dispersed in an organic polymer epoxy resin as a conductive filler, and the polymer containing the conductive filler is evenly coated on the side of the uncapped layer of the silicon carbide film to ensure that the array gaps are filled. The polymer coating thickness is 400 μm, and the film is kept at 80℃ for 200 minutes for drying. Subsequently, the polymer on the uncapped layer of the silicon carbide nanostructure array film is cleaned by plasma until 40 μm of the nanostructure array is exposed, and finally a layer of polymer without conductive filler with a thickness of 60 μm is spin-coated on the exposed nanostructure array.

[0072] (4) Construction of a piezoelectric nanogenerator with all-weather service capability: Based on the third step, a layer of gold, platinum and copper alloy with a thickness of 50 nm is magnetron sputtered on the two surfaces of silicon carbide as the upper and lower electrodes. After the two electrodes are led out, the entire device is completely encapsulated with a polymer on a PP substrate to obtain a piezoelectric nanogenerator.

[0073] (5) Service of the piezoelectric nanogenerator: The piezoelectric nanogenerator is vibrated along the thickness direction by using a hair dryer. According to the positive piezoelectric effect, a dipole with highly consistent polarization direction is generated inside the single crystal silicon carbide, and a significant electrical signal output is shown in the macroscopic view. The output current density of the piezoelectric nanogenerator prepared in the embodiment of the present invention when vibrated by the hair dryer is as follows: Fig. 9 As shown, Fig. 9It can be shown that the piezoelectric nanogenerator prepared by the embodiment of the present invention has a strong ability to collect and convert low-frequency mechanical energy generated by the movement of objects in nature. The piezoelectric nanogenerator was placed in a temperature condition of 80°C and a relative humidity condition of 100% and operated for 400 days. The piezoelectric nanogenerator still maintained a stable output, showing an extremely wide temperature and relative humidity operating range and excellent long-term service stability. The output current density of the piezoelectric nanogenerator prepared by the embodiment of the present invention when working in an environment with a temperature of 80°C is as follows: Fig.11 As shown, the output current density of the piezoelectric nanogenerator prepared in the embodiment of the present invention when working in an environment with a relative humidity of 100% is as follows Fig.13 As shown. Fig.11 and Fig.13 It can be explained that the piezoelectric nanogenerator prepared in the embodiment of the present invention can still maintain a high output in an extreme environment of a temperature of 80°C and a relative humidity of 100%, fully demonstrating its stability against temperature and humidity, indicating that it can be fully applied in all-weather service environments around the world.

[0074] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array, characterized in that: The steps include: Preparation of N-doped silicon carbide: using N2O5 as a nitrogen source, doping a silicon carbide single crystal wafer for 1-20 hours at a temperature of 1000-1500°C, a pressure of 100-500 Pa, and an argon atmosphere to obtain silicon carbide with a nitrogen doping concentration of 0.1-10 mol%; Preparation of self-supporting silicon carbide nanostructure array film: electrochemically etching the carbon surface or silicon surface of N-doped silicon carbide to form a silicon carbide nanostructure array film with a thickness of 50-300 μm and a morphology of nanopores, nanobelts, nanorods or nanowires; Optimization of silicon carbide nanostructure array film performance: including, In an air or oxygen atmosphere, the silicon carbide forming the silicon carbide nanostructure array film is kept at a temperature of 1300-1800° C. for 1-24 hours to form a SiO2 oxide layer on the surface of the silicon carbide; The polymer dispersed with the conductive filler is coated on the silicon carbide nanostructure array film of the silicon carbide with the SiO2 oxide layer formed on the surface, and after drying, a conductive filler polymer coating layer with a thickness of 100-500 μm is formed; Using plasma to clean the polymer on the silicon carbide nanostructure array film until the nanostructure array is exposed by 10-50 μm; Spin coating a layer of polymer without conductive filler on the silicon carbide nanostructure array film, and drying to form a polymer layer without conductive filler with a thickness of 20-80 μm; Construct a piezoelectric nanogenerator with all-weather service capability: magnetron sputter a layer of metal with a thickness of 10-100nm on both sides of silicon carbide as the upper and lower electrodes, lead out the wires and package the entire device on a substrate to obtain a piezoelectric nanogenerator with all-weather service capability.

2. The method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array according to claim 1, characterized in that: The silicon carbide single crystal wafer is a single-sided or double-sided polished silicon carbide single crystal wafer with a thickness of 100-500 μm and a crystal type of 2H, 4H or 6H.

3. The method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array according to claim 1, characterized in that: The electrochemical etching adopts a power source of 5-50V direct current or pulse voltage and 100-500mA direct current or pulse current, the pulse waveform is a sine wave, a triangle wave or a rectangular wave, and the pulse duty ratio is 10-90%.

4. The method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array according to claim 3, characterized in that: The amount of etching solution used in the electrochemical etching is 10-50 ml, and the etching time is 1-100 min.

5. The method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array according to claim 4, characterized in that: The etching solution is a mixture of hydrofluoric acid, ethanol and hydrogen peroxide, and the mass ratio of the hydrofluoric acid, ethanol and hydrogen peroxide is (1-20): (1-20): (0-10).

6. The method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array according to claim 1, characterized in that: The conductive filler is MXene, graphene, carbon black or metal powder, and the morphology of the conductive filler is nanoparticles, nanowires, nanorods, nanotubes, nanobelts or nanosheets.

7. The method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array according to claim 6, characterized in that: The polymer is PDMS, PMMA or epoxy resin.

8. The method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array according to claim 7, characterized in that: The polymer is dried at a temperature of 60-100° C. for 30-300 minutes.

9. The method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array according to claim 1, characterized in that: The metal magnetron sputtered on both sides of silicon carbide is copper, aluminum, silver, gold or / and platinum, and the substrate is PE, PET, PP, PS or PVC.

10. The method for preparing a piezoelectric nanogenerator with all-weather service capability based on an N-doped SiC nanostructure array according to any one of claims 1 to 9, characterized in that: The piezoelectric nanogenerator can stably output for 300-500 days under the conditions of a temperature of -80°C to 80°C and a relative humidity of 0-100%.

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