Moisture-friction-resistant nano generator and fog water collection and environment monitoring device

Abstract

The invention discloses a wet-friction-resistant nano generator and a fog water collecting and environment monitoring device.The wet-friction-resistant nano generator comprises a positive friction layer, a negative friction layer, a negative friction layer electrode and an external circuit, the negative friction layer is attached to the negative friction layer electrode, the positive friction layer is opposite to the negative friction layer in position, and the negative friction layer is attached to the negative friction layer electrode. The negative friction layer can be mutually contacted and separated, and is an F-MXene / fluorine-containing high polymer nanofiber membrane. According to the wet-friction-resistant nano-generator provided by the invention, the frictional electricity effect of the frictional nano-generator can be enhanced, relatively high output performance of the frictional nano-generator can be kept in a high-humidity and acid-base environment, the frictional electricity output voltage of the frictional nano-generator is changed along with a test environment, a good linear relation is shown, and the wet-friction-resistant nano-generator can be applied to the field of wet-friction-resistant nano-generators. The application potential of atmospheric environment monitoring is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of triboelectric nanogenerators, and in particular to a moisture-resistant triboelectric nanogenerator and a fog water collection and environment monitoring device. Background Art

[0002] As an emerging energy harvesting and signal sensing technology, the triboelectric nanogenerator (TENG) offers numerous unique advantages. Its highly sensitive mechanical response and wideband signal capture capabilities enable efficient capture of various weak mechanical signals. Its low-power, self-sustaining design eliminates the need for frequent power supply changes, reducing operational costs. Its multi-dimensional structural design flexibility allows for customization for diverse application scenarios. Leveraging these advantages, TENGs are demonstrating significant application value in intelligent monitoring systems, wearable medical devices, and self-powered sensing, providing a new technological path for the development of related fields.

[0003] However, TENG faces significant challenges in practical applications. Its performance is significantly affected by ambient humidity. When exposed to high humidity, water molecules form conductive pathways at the material interface, accelerating the dissipation of interfacial charge. This phenomenon causes the TENG's surface potential to decay, resulting in an exponential decrease in triboelectric output performance. This characteristic severely limits the reliability of TENG applications in typical high-humidity scenarios, such as marine and tropical rainforest ecological monitoring and outdoor sportswear. It makes it difficult to operate stably in complex and humid environments, preventing the full realization of its technological advantages.

[0004] Therefore, how to overcome the impact of environmental factors on TENG performance, develop TENG that can maintain stable performance in high humidity environments, and further explore its application potential in the field of environmental monitoring has become a technical problem that needs to be solved urgently. Summary of the Invention

[0005] In order to solve the above technical problems, the primary purpose of the present invention is to provide a moisture-resistant triboelectric nanogenerator.

[0006] Another object of the present invention is to provide a fog water collection and environment monitoring device.

[0007] The third object of the present invention is to provide the application of the above-mentioned moisture-resistant friction nanogenerator or fog water collection and environmental monitoring device in water and electricity collection and environmental monitoring.

[0008] The present invention is achieved through the following technical solutions:

[0009] A first aspect of the present invention provides an F-MXene / fluorinated polymer nanofiber membrane, which is prepared by the following method: dispersing F-MXene and a fluorinated polymer in a solvent, and electrospinning the obtained composite spinning solution to obtain the F-MXene / fluorinated polymer nanofiber membrane; the F-MXene is prepared by surface fluorination modification of MXene with fluorinated silane; the fluorinated polymer is selected from one or more of polytetrafluoroethylene (PTFE), polytetrafluoroethylene-hexafluoropropylene (FEP), polytetrafluoroethylene-ethylene (ETFE), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) and polyvinylidene fluoride-tetrafluoroethylene (PVDF-TFE).

[0010] The present invention prepares composite nanofiber membranes through electrospinning, which induces the formation of β-phase crystals in the nanofiber membranes, thereby improving triboelectric performance. F-MXene nanosheets are doped into the nanofibers for dielectric regulation, increasing the electronegativity and surface charge density of the nanofibers. This also enhances the electronegativity and hydrophobicity of the friction layer material, thereby improving the output performance and moisture resistance of the triboelectric nanogenerator, maintaining stable output in high-humidity environments, which is particularly important for energy harvesting and environmental monitoring.

[0011] Furthermore, the F-MXene is prepared by the following method: adding MXene to an ethanol solution of 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFOTS) to react to obtain F-MXene.

[0012] This invention modifies the highly conductive two-dimensional titanium carbene (MXene) material through fluorination to produce F-MXene. The hydrophobic protective layer formed by the numerous F-groups on the F-MXene surface effectively prevents direct contact between the F-MXene and air / water, resulting in high antioxidant stability in high-humidity environments and water. Furthermore, the strong electronegativity of the F element in F-MXene lays the foundation for the development of high-output, highly stable, moisture-resistant triboelectric nanogenerators.

[0013] Furthermore, the concentration of PFOTS in the PFOTS ethanol solution is 2-6 wt %; the concentration of MXene in the PFOTS ethanol solution is 0.1-2 wt %.

[0014] Furthermore, the reaction time is 4-12 hours.

[0015] In a specific embodiment, PFOTS is prepared into an ethanol solution, and MXene is added and stirred at room temperature for a co-condensation reaction. After the reaction is completed, high-speed centrifugation is performed, and the solution is washed by centrifugation with ethanol, and freeze-dried to obtain MXene with a surface grafted fluoroalkyl chain (F-MXene).

[0016] Furthermore, the molecular weight of the fluorine-containing polymer is 300-800 kDa.

[0017] Furthermore, the content of the fluorinated polymer in the composite spinning solution is 14-16 wt %, and the mass of the F-MXene is 3-12% of the mass of the fluorinated polymer.

[0018] Preferably, the mass of the F-MXene is 6-9% of the mass of the fluorinated polymer.

[0019] Furthermore, the solvent is a mixed solvent of DMF and acetone, and the volume ratio of DMF to acetone is 6:4.

[0020] Furthermore, the process parameters of the electrospinning are: spinning voltage of 16-20 kV, spinning solution flow rate of 0.8-1.0 mL / h, and spinning distance of 13-15 cm.

[0021] Furthermore, the water contact angle of the F-MXene / fluorinated polymer nanofiber membrane is greater than 140°, and the triboelectric output voltage retention rate is greater than 80% in a high humidity environment with a relative humidity (RH) greater than 75%.

[0022] The second aspect of the present invention provides a moisture-resistant friction nanogenerator, comprising a positive friction layer, a negative friction layer, a negative friction layer electrode, and an external circuit. The negative friction layer is adhered to the negative friction layer electrode. The positive friction layer and the negative friction layer are positioned opposite to each other and can contact and separate from each other. The negative friction layer is the F-MXene / fluorinated polymer nanofiber membrane described in the first aspect.

[0023] Based on the micro-droplet dynamics and solid-liquid frictional electrification mechanism, the moisture-resistant friction nanogenerator provided by the present invention is expected to promote the transformation of environmental monitoring from traditional active sensing to a new self-powered and intelligent method.

[0024] A third aspect of the present invention provides a fog water collection and environment monitoring device, comprising:

[0025] a back electrode, serving as a supporting substrate;

[0026] A fiber membrane is arranged on one side of the back electrode;

[0027] a top electrode, locally disposed on a side of the fiber membrane away from the back electrode and located at a collecting end of the fiber membrane, the top electrode being electrically connected to the back electrode via an external circuit;

[0028] Wherein, the top electrode only covers a portion of the fiber membrane, and a hydrophilic point array is formed by in-situ polymerization of dopamine in the exposed area of ​​the fiber membrane not covered by the top electrode; the fiber membrane is the F-MXene / fluorinated polymer nanofiber membrane described in the first aspect;

[0029] The mist water collection and environment monitoring device is arranged to be inclined relative to the horizontal plane, with an inclination angle of 40°-80°.

[0030] Furthermore, the diameter of the hydrophilic spots in the hydrophilic spot array is 1.5-2.4 mm, and the edge spacing of the hydrophilic spots is 3-8 mm.

[0031] Furthermore, the specific method for forming a hydrophilic point array by in-situ polymerization of dopamine in the exposed area of ​​the fiber membrane not covered by the top electrode is: adding dichloromethane to the surface of the fiber membrane, and then adding dopamine solution, to cause oxidative self-polymerization to form a hydrophilic point array.

[0032] Furthermore, the concentration of dopamine in the dopamine solution is 6-12 g / L.

[0033] In a specific embodiment, the specific method for forming a hydrophilic point array by in situ polymerization of dopamine in the exposed area of ​​the fiber membrane not covered by the top electrode is: after adding dichloromethane to the surface of the fiber membrane for wetting, a dopamine solution containing trishydroxymethylaminomethane hydrochloride (Tris-HCl, pH = 8.5) is added, and the membrane is placed at room temperature for oxidative self-polymerization to form a stable PDA coating, which is a hydrophilic point array.

[0034] Furthermore, the back electrode and the top electrode are connected via an external circuit and an electrometer is connected therebetween.

[0035] Specifically, the F-MXene / fluorinated polymer nanofiber membrane and the top electrode described in the first aspect are attached to a copper plate of the same size, a hydrophilic point array is formed on the surface of the F-MXene / fluorinated polymer nanofiber membrane by in situ polymerization of dopamine (PDA), and a rectangular copper sheet is fixed to the bottom below the hydrophilic point array of the F-MXene / fluorinated polymer nanofiber membrane. The copper plate and the copper sheet are used as two electrodes respectively, and are connected to an electrometer with a copper wire. The fog water collection and environmental monitoring device is installed in the atmospheric environment at an angle of 40°-80° to the horizontal plane.

[0036] The fourth aspect of the present invention provides an application of the moisture-resistant friction nanogenerator described in the second aspect or the fog water collection and environmental monitoring device described in the third aspect in energy collection and environmental monitoring.

[0037] Furthermore, the fog water collection and environmental monitoring device can be used to collect water resources and electricity in marine environments, tropical rainforests or industrial high-humidity scenes. It can also be used as a self-powered sensor to monitor fog environmental pollution in real time, including acidic substances, volatile organic compounds (VOCs) and PM2.5. 2.5 .

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. This invention prepares composite nanofiber membranes through electrospinning. The electrospinning process induces the formation of β-phase crystals in the nanofiber membranes, which can improve triboelectric properties. F-MXene nanosheets are doped into the nanofibers for dielectric regulation, increasing the electronegativity and surface charge density of the nanofibers. This also enhances the electronegativity and hydrophobicity of the friction layer material, thereby improving the output performance and moisture resistance of the triboelectric nanogenerator, maintaining stable output in high-humidity environments, which is particularly important for energy harvesting and environmental monitoring.

[0040] 2. The moisture-resistant triboelectric nanogenerator provided by the present invention can not only enhance the triboelectric effect of the triboelectric nanogenerator, but also enable it to maintain a high output performance in high humidity and acidic and alkaline environments. In addition, the triboelectric output voltage of the triboelectric nanogenerator changes with the test environment, showing a good linear relationship, and has the potential for application in atmospheric environment monitoring.

[0041] 3. This invention utilizes a composite fiber membrane-based triboelectric nanogenerator as its foundation. Hydrophilic sites are formed on the composite fiber membrane to create a biomimetic water harvesting material for efficient fog water collection. Simultaneously, as the fog forms droplets and slides on the surface, friction with the fiber membrane generates electrical signals for energy harvesting. Because the environment and composition of water mist vary, such as flow rate, pH, formaldehyde, and particulate matter content, which all have varying effects on triboelectric performance, the electrical signals generated by friction can be used for real-time environmental monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of the preparation process and principle of F-Mxene.

[0043] Figure 2 SEM images of MAX, multilayer MXene, monolayer MXene and F-MXene; among them, (a) is MAX, (b) is multilayer MXene, (c) is monolayer MXene, and (d) is F-MXene.

[0044] Figure 3 These are actual photos of the dispersions of MXene and F-MXene after being dispersed in water and placed for different times (0, 10, 17, and 24 days from left to right).

[0045] Figure 4SEM images and oxygen element scanning electron spectra of MXene and F-MXene dispersed in water for 24 days; (a) is the SEM image of MXene dispersed in water for 24 days, (b) is the oxygen element distribution map and ratio of (a), (c) is the SEM image of F-MXene dispersed in water for 24 days, and (d) is the oxygen element distribution map and ratio of (c).

[0046] Figure 5 This is a flow chart for the preparation of the F-MXene / PVDF-HFP nanofiber membrane and the moisture-resistant triboelectric nanogenerator in Example 1.

[0047] Figure 6 This is the fog water collection principle and solid-liquid friction nanogenerator schematic of the fog water collection and power generation device.

[0048] Figure 7 These are the surface morphology SEM images of the F-MXene / PVDF-HFP nanofiber membrane in Example 5 before and after the hydrophilic point array is formed by in situ polymerization of dopamine; wherein, (a) is the surface morphology SEM image before the hydrophilic point array is formed by in situ polymerization of dopamine, and (b) is the surface morphology SEM image after the hydrophilic point array is formed by in situ polymerization of dopamine.

[0049] Figure 8 These are the surface water contact angle data graphs of the F-MXene / PVDF-HFP nanofiber membrane in Example 5 before and after the hydrophilic point array is formed by in situ polymerization of dopamine; wherein, (a) is the water contact angle data graph before the hydrophilic point array is formed by in situ polymerization of dopamine, and (b) is the water contact angle data graph after the hydrophilic point array is formed by in situ polymerization of dopamine.

[0050] Figure 9 These are the SEM images and fiber diameter distribution diagrams of the F-MXene / PVDF-HFP nanofiber membranes in Examples 1-4; wherein, (a) is the SEM image of Example 1, (b) is the fiber diameter distribution diagram of Example 1, (c) is the SEM image of Example 2, (d) is the fiber diameter distribution diagram of Example 2, (e) is the SEM image of Example 3, (f) is the fiber diameter distribution diagram of Example 3, (g) is the SEM image of Example 4, and (h) is the fiber diameter distribution diagram of Example 4.

[0051] Figure 10These are the SEM images and fiber diameter distribution diagrams of the MXene / PVDF-HFP nanofiber membranes in Comparative Examples 1-4; wherein, (a) is the SEM image of Comparative Example 1, (b) is the fiber diameter distribution diagram of Comparative Example 1, (c) is the SEM image of Comparative Example 2, (d) is the fiber diameter distribution diagram of Comparative Example 2, (e) is the SEM image of Comparative Example 3, (f) is the fiber diameter distribution diagram of Comparative Example 3, (g) is the SEM image of Comparative Example 4, and (h) is the fiber diameter distribution diagram of Comparative Example 4.

[0052] Figure 11 These are the water contact angle data graphs for the F-MXene / PVDF-HFP nanofiber membranes in Examples 1-4, the MXene / PVDF-HFP nanofiber membranes in Comparative Examples 1-4, and the PVDF-HFP nanofiber membrane in Comparative Example 5.

[0053] Figure 12 The open circuit voltage, short circuit current and transfer charge spectra of the moisture-resistant friction nanogenerators prepared in Examples 1-4 and the friction nanogenerators prepared in Comparative Examples 1-5 were measured at an ambient humidity of 50% RH; wherein, (a) is the open circuit voltage spectrum of Comparative Examples 1-5, (b) is the short circuit current spectrum of Comparative Examples 1-5, (c) is the transfer charge spectrum of Comparative Examples 1-5, (d) is the open circuit voltage spectrum of Examples 1-4 and Comparative Example 5, (e) is the short circuit current spectrum of Examples 1-4 and Comparative Example 5, and (f) is the transfer charge spectrum of Examples 1-4 and Comparative Example 5. (a), (b) and (c) are Comparative Example 5, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 from left to right, and (d), (e) and (f) are Comparative Example 5, Example 1, Example 2, Example 3 and Example 4 from left to right.

[0054] Figure 13 The open circuit voltage, short circuit current and transfer charge spectra of the output of the moisture-resistant friction nanogenerator prepared in Example 3 and the friction nanogenerator prepared in Comparative Example 3 were measured at different humidity levels (RH 50%, RH 60%, RH 70%, and RH 80% from left to right); among them, (a) is the open circuit voltage spectrum of Comparative Example 3, (b) is the short circuit current spectrum of Comparative Example 3, (c) is the transfer charge spectrum of Comparative Example 3, (d) is the open circuit voltage spectrum of Example 3, (e) is the short circuit current spectrum of Example 3, and (f) is the transfer charge spectrum of Example 3.

[0055] Figure 14The open circuit voltage, short circuit current and transfer charge spectra of the moisture-resistant triboelectric nanogenerator prepared in Example 3 and the triboelectric nanogenerator prepared in Comparative Example 3 were measured after being treated with different pH solutions (pH 0, 3, 6, 8, 11, and 14 from left to right) at an ambient humidity of 50% RH; among them, (a) is the open circuit voltage spectrum of Comparative Example 3, (b) is the short circuit current spectrum of Comparative Example 3, (c) is the transfer charge spectrum of Comparative Example 3, (d) is the open circuit voltage spectrum of Example 3, (e) is the short circuit current spectrum of Example 3, and (f) is the transfer charge spectrum of Example 3.

[0056] Figure 15 The open circuit voltage spectra of the output of the moisture-resistant triboelectric nanogenerator prepared in Example 3 and the triboelectric nanogenerator prepared in Comparative Example 3 were measured after being placed in a high humidity environment (80% RH) for different time periods (0 days, 25 days, 50 days, and 75 days from left to right); among them, (a) is the open circuit voltage spectrum of the triboelectric nanogenerator prepared in Comparative Example 3, and (b) is the open circuit voltage spectrum of the moisture-resistant triboelectric nanogenerator prepared in Example 3.

[0057] Figure 16 The water collection efficiency and triboelectric output spectra of the mist water collection and environmental monitoring device prepared in Example 5 at different mist flow rates (60, 120, 180, 240, and 300 mL / h from left to right); among them, (a) is the water collection efficiency data graph at different mist flow rates, and (b) is the triboelectric power generation output voltage signal graph at different mist flow rates.

[0058] Figure 17 The triboelectric output voltage spectrum, the fitting curve diagram of pH and voltage, and the schematic diagram of the effect of ion adsorption on surface charge distribution of the fog water collection and environmental monitoring device prepared in Example 5 under different pH fog water (from left to right, pH is 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, and 7, respectively); among which, (a) is the triboelectric output voltage spectrum, (b) is the fitting curve diagram of pH and voltage, and (c) is a schematic diagram of the effect of ion adsorption on surface charge distribution.

[0059] Figure 18 The fog water collection and environmental monitoring device prepared in Example 5 is placed under different formaldehyde concentrations (from left to right, the concentrations are 0 mg / L, 0.005·10 -3 mg / L, 0.01·10 -3 mg / L, 0.02·10 -3 mg / L, 0.03·10 - 3 mg / L, 0.08·10 -3 mg / L, 0.14·10-3 mg / L, 0.20·10 -3 mg / L, 0.30·10 -3 Figure 3. Triboelectric output voltage spectrum of the sample (mg / L), fitting curve of formaldehyde concentration and voltage, and schematic diagram of the effect of hydrogen bonds between formaldehyde and water molecules on the surface charge; (a) is the triboelectric output voltage spectrum, (b) is the fitting curve of formaldehyde concentration and voltage, and (c) is a schematic diagram of the effect of hydrogen bonds between formaldehyde and water molecules on the surface charge.

[0060] Figure 19 The fog water collection and environmental monitoring device prepared in Example 5 was tested under different PM 2.5 Concentration of fog water (from left to right the concentration is 35·10 -3 μg / L, 75·10 -3 μg / L, 115·10 -3 μg / L, 150·10 -3 μg / L, 250·10 -3 μg / L, 500·10 -3 μg / L, 750·10 -3 μg / L, 1000·10 -3 μg / L) triboelectric output voltage spectrum, PM 2.5 The fitting curve of concentration and voltage and the schematic diagram of the working mechanism of the influence of particulate matter on the output of the fog water collection and environmental monitoring device; among them, (a) is the triboelectric output voltage of fog water with different particulate matter contents, (b) is the fitting curve of voltage, and (c) is the schematic diagram of the working mechanism of the influence of particulate matter on the output of the fog water collection and environmental monitoring device. DETAILED DESCRIPTION

[0061] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0062] The present invention provides a moisture-resistant triboelectric nanogenerator, comprising a positive friction layer, a negative friction layer, a negative friction layer electrode, and an external circuit. The negative friction layer is attached to the negative friction layer electrode. The positive friction layer and the negative friction layer are positioned opposite to each other and can contact and separate from each other. The negative friction layer is an F-MXene / fluorinated polymer nanofiber membrane.

[0063] The F-MXene is prepared by surface fluorination modification of MXene with fluorinated silane; the F-MXene / fluorinated polymer nanofiber membrane is prepared by the following method: F-MXene and fluorinated polymer are dispersed in a solvent, and the obtained composite spinning solution is subjected to electrospinning to obtain the F-MXene / fluorinated polymer nanofiber membrane; the fluorinated polymer is selected from one or more of polytetrafluoroethylene (PTFE), polytetrafluoroethylene-hexafluoropropylene (FEP), polytetrafluoroethylene-ethylene (ETFE), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) and polyvinylidene fluoride-tetrafluoroethylene (PVDF-TFE).

[0064] In a specific embodiment, the preparation of the MXene comprises the following steps:

[0065] (1) The raw material MAX (Ti3AlC2) is added to a mixed solution of hydrofluoric acid, concentrated hydrochloric acid and water, heated and stirred to etch the Al layer, and then centrifuged and washed to obtain multilayer MXene;

[0066] (2) The multilayer MXene is added to a lithium chloride solution, stirred at room temperature, washed by centrifugation, and then ultrasonically treated in an ice bath. The unpeeled multilayer MXene is then removed by low-speed centrifugation. The supernatant is centrifuged at high speed to obtain a single-layer MXene. The single-layer MXene powder is obtained after freeze-drying, namely MXene.

[0067] In a specific embodiment, in step (1), the volume ratio of hydrofluoric acid to concentrated hydrochloric acid in the mixed solution of hydrofluoric acid, concentrated hydrochloric acid and water is 1:(0-1), the volume ratio of the total volume of the hydrofluoric acid and concentrated hydrochloric acid to water is (3-5):1, the mass concentration of the MAX in the mixed solution is 3-5%, the etching temperature is 25-36°C, and the etching time is 12-18h.

[0068] In a specific embodiment, in step (2), the concentration of the lithium chloride solution is 3-5 wt %, the concentration of the multilayer MXene in the lithium chloride solution is 2-5 wt %, the stirring treatment time is 12-18 h, and the ultrasonic treatment time is 20-40 min.

[0069] In a specific embodiment, the F-MXene is prepared by the following method: MXene is added to an ethanol solution of 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFOTS) to react to obtain F-MXene. The preparation process and principle diagram of F-MXene are shown in FIG. Figure 1 shown.

[0070] The present invention also provides a fog water collection and environmental monitoring device, comprising a back electrode, the F-MXene / fluorinated polymer nanofiber membrane and a top electrode according to the first aspect, which are sequentially arranged on one side of the back electrode, wherein the top electrode does not completely cover the F-MXene / fluorinated polymer nanofiber membrane, the top electrode is located in a direction close to a horizontal plane, and a hydrophilic point array is formed by in-situ polymerization of dopamine on a side of the F-MXene / fluorinated polymer nanofiber membrane away from the back electrode and not covered by the top electrode, the back electrode and the top electrode are connected via an external circuit, and the angle between the fog water collection and environmental monitoring device and the horizontal plane is 40°-80°;

[0071] The F-MXene / fluorinated polymer nanofiber membrane is prepared by the following method: F-MXene and a fluorinated polymer are dispersed in a solvent, and the obtained composite spinning solution is subjected to electrospinning to obtain the F-MXene / fluorinated polymer nanofiber membrane; the F-MXene is prepared by surface fluorination modification of MXene with fluorinated silane; the fluorinated polymer is selected from one or more of polytetrafluoroethylene, polytetrafluoroethylene-hexafluoropropylene, polytetrafluoroethylene-ethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene and polyvinylidene fluoride-tetrafluoroethylene.

[0072] Unless otherwise specified, the experimental methods used in the following examples and comparative examples are conventional methods, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0073] In the present invention, unless otherwise specified, the raw material information involved in the examples and comparative examples of the present invention is as follows: MAX (Ti3AlC2) was purchased from Beijing Beike New Materials Technology Co., Ltd.; hydrofluoric acid (HF) was purchased from Shanghai Jizhi Biochemical Co., Ltd.; polyvinylidene fluoride (PVDF) was purchased from Shanghai Dibai Biotechnology Co., Ltd.; hydrochloric acid (HCl) was purchased from Sinopharm Chemical Reagent Co., Ltd.; lithium chloride (LiCl) was purchased from Shanghai Sinopharm Chemical Reagent Co., Ltd.; 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFOTS) was purchased from Shanghai Shaoyuan Technology Co., Ltd.; anhydrous ethanol was purchased from Jiangsu Qiangsheng Functional Chemical Co., Ltd.; polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) was purchased from Dongguan Zhanyang Polymer Materials Co., Ltd., with a molecular weight of 400kDa; dimethylformamide (DMFOTS) was purchased from Shanghai Shaoyuan Technology Co., Ltd. F) was purchased from Taicang Hushi Reagent Co., Ltd.; acetone was purchased from Jiangsu Qiangsheng Functional Chemical Co., Ltd.; sodium hydroxide (NaOH) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; dopamine (DA) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; dichloromethane (DCM) was purchased from Sinopharm Chemical Reagent Suzhou Co., Ltd.; sulfuric acid was purchased from Shanghai Lingfeng Chemical Reagent Co., Ltd.; formaldehyde aqueous solution was purchased from Sinopharm Chemical Reagent Co., Ltd.; high-purity oxygen-free copper foil (Cu) was purchased from Hefei Wenghe Metal Materials Co., Ltd.; transparent acrylic substrate was purchased from Wenzhou Tangminji Building Materials Co., Ltd.; trishydroxymethylaminomethane hydrochloride (Tris-HCl) was purchased from Fuzhou Feijing Biotechnology Co., Ltd.; cigarette cakes were purchased from Changzhou Madelu Trading Co., Ltd.; conductive glue was purchased from China Scientific Research Microscope Consumables Co., Ltd.; and wires were purchased from Yueqing Youning Electric Co., Ltd.

[0074] In the present invention, unless otherwise specified, the open circuit voltage, short circuit current, and transfer charge tested in the test examples of the present invention were measured using a graphic sampling multimeter, model DMM7510, purchased from KEITHLEY; a high resistance / low current electrometer, model 6514, purchased from KEITHLEY; and a triboelectric performance test platform built in the laboratory.

[0075] In the present invention, unless otherwise specified, the simulated water mist test in the test examples of the present invention uses a humidifier, model D205, purchased from Beijing Yadu Technology Co., Ltd.

[0076] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0077] The preparation method of the F-MXene powder used in the following examples includes the following steps:

[0078] (1) Etching treatment: Add 20 mL of hydrofluoric acid, 20 mL of concentrated hydrochloric acid, and 10 mL of deionized water into a polytetrafluoroethylene bottle and set a constant temperature of 35°C with magnetic stirring. When the temperature rises to 35°C, slowly add 2 g of MAX (Ti3AlC2) powder to the mixed solution several times and react for 12 hours under constant temperature and magnetic stirring at 600 rpm. After the reaction is completed, pour the solution into a centrifuge tube and centrifuge it, discard the supernatant, add deionized water and repeat the centrifugation to wash away the residual acid in the reaction until the pH of the supernatant is ≥6, and a multilayer MXene precipitate is obtained;

[0079] (2) Intercalation treatment: Pour 2g of lithium chloride powder into a beaker, then add 40mL of deionized water, stir thoroughly to dissolve, then pour into the multilayer MXene precipitate, shake manually, and pour into the beaker. After magnetic stirring at 500rpm for 12 hours at room temperature, pour into a centrifuge tube and centrifuge at 12000rpm, discard the supernatant, and retain the precipitate. Add deionized water and repeat the centrifugation several times, then ultrasonically treat in an ice bath for 20 minutes, centrifuge at 4500rpm to remove the unpeeled multilayer MXene, and the upper solution is a single-layer MXene. Centrifuge the upper solution at 12000rpm, retain the precipitate, and freeze-dry for 24 hours to obtain a single-layer MXene powder;

[0080] (3) Fluorination modification: 50 mg of monolayer MXene powder was added to 40 mL of 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFOTS, 5 wt%) ethanol solution and reacted with magnetic stirring at room temperature for 8 hours. After the reaction, the precipitate was centrifuged at 12000 rpm and repeatedly washed with ethanol to remove excess PFOTS. Finally, it was freeze-dried to obtain fluorinated MXene (F-MXene) powder.

[0081] Figure 2 Scanning electron microscope (SEM) images of MAX, multilayer MXene, single-layer MXene, and F-MXene; (a) is MAX, (b) is multilayer MXene, (c) is single-layer MXene, and (d) is F-MXene. Figure 2It can be seen that the original phase of MAX (Ti3AlC2) shows a multi-layered structure. This layered structure is a typical feature of the MAX phase and provides a basis for the subsequent synthesis of MXene. The SEM image of the multilayer MXene shows a clear "accordion" structure, which is a sign of successful etching. This structure is formed because the middle Al layer is etched away, and the rapid generation of H2 during HF etching causes the layered structure to expand. A single-layer MXene can be obtained by intercalating and exfoliating the multilayer MXene. It can be seen that the single-layer MXene has a thin lamellar structure, and a single nanosheet is a smooth, two-dimensional structure with irregular edges. Compared with the single-layer MXene, the SEM image of F-MXene has a generally consistent microscopic morphology, but wrinkles are formed on the surface.

[0082] Figure 3 Actual photos of MXene and F-MXene dispersions in water after being placed for different periods of time. Figure 3 The figure shows that the color of the MXene dispersion gradually changes from black to white over time, indicating that it is gradually oxidized and is almost completely oxidized after 24 days. However, the color of the F-MXene dispersion remains black after 24 days, with little change, indicating that F-MXene is highly stable in humid environments. This is because the hydrophobic protective layer formed on the MXene surface prevents direct contact with air / water and hinders its oxidation at the contact surface.

[0083] Figure 4 SEM images and oxygen scanning electron spectra of MXene and F-MXene dispersed in water for 24 days. (a) SEM image of MXene after 24 days, (b) oxygen distribution and ratio of (a), (c) SEM image of F-MXene after 24 days, and (d) oxygen distribution and ratio of (c). The original MXene flakes have a clean and smooth surface. However, after 24 days of dispersion in water, some large defects and nanoparticles appear, and the original flaky structure disappears. The modified F-MXene retains its original flaky structure after 24 days of dispersion in water, demonstrating unique stability. After 24 days, the MXene surface is enriched with oxygen, reaching 65.7 wt%, due to the formation of a large amount of TiO2 through oxidation. However, the surface oxygen content of F-MXene remains low, consistent with the original content (primarily from oxygen on the MXene surface and PFOTS), demonstrating its antioxidant stability in water.

[0084] Example 1

[0085] A moisture-resistant friction nanogenerator includes a positive friction layer, a negative friction layer, a negative friction layer electrode, and an external circuit. The negative friction layer is attached to the negative friction layer electrode. The positive friction layer and the negative friction layer are positioned opposite to each other and can contact and separate from each other. The positive friction layer is copper foil, the negative friction layer is F-MXene / polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) nanofiber membrane, and the negative friction layer electrode is a copper sheet.

[0086] The preparation method of the moisture-resistant triboelectric nanogenerator of Example 1 comprises the following steps:

[0087] S1. Preparation of composite spinning solution: F-MXene powder was added to a mixed solvent of DMF and acetone in a volume ratio of 6:4, and ultrasonic vibration was used to uniformly disperse it. Then, PVDF-HFP powder was added to the obtained mixed solution, and magnetic stirring was performed at a constant temperature of 60°C for 4 hours to obtain a composite spinning solution. The PVDF-HFP content in the composite spinning solution was controlled to be 14 wt% and the F-MXene was 3% by weight of the PVDF-HFP.

[0088] S2. Preparation of nanofiber membrane: The composite spinning solution was loaded into the electrospinning equipment, and the electrospinning process parameters were set as follows: spinning voltage of 18 kV, receiving distance of 15 cm, micropump pushing speed of 1.0 mL / h, and receiving device speed of 300 rpm. Electrospinning was performed and the nanofibers were deposited onto a collecting drum. The spinning time was controlled to 3 h to obtain F-MXene / PVDF-HFP nanofiber membrane.

[0089] S3. Preparation of a moisture-resistant triboelectric nanogenerator: A single-electrode moisture-resistant triboelectric nanogenerator was prepared using an F-MXene / PVDF-HFP nanofiber membrane as the negative friction layer. Copper foil was used as the positive friction layer, a copper sheet was used as the negative friction layer electrode, and copper wire was used as the conductor. The copper sheet was cut into 5cm × 5cm pieces and attached to an acrylic plate. The F-MXene / PVDF-HFP nanofiber membrane was then cut into 5cm × 5cm pieces and placed on a copper sheet of the same size. Conductive tape was used to attach the copper wire between the nanofiber membrane and the copper sheet to create a moisture-resistant triboelectric nanogenerator.

[0090] Figure 5 This is a flow chart for the preparation of the F-MXene / PVDF-HFP nanofiber membrane and the moisture-resistant triboelectric nanogenerator in Example 1.

[0091] Example 2

[0092] A moisture-resistant triboelectric nanogenerator is prepared by a method substantially the same as that in Example 1, except that in S1, F-MXene accounts for 6% of the mass of PVDF-HFP.

[0093] Example 3

[0094] A moisture-resistant triboelectric nanogenerator is prepared by a method substantially the same as that in Example 1, except that in S1, F-MXene accounts for 9% of the mass of PVDF-HFP.

[0095] Example 4

[0096] A moisture-resistant triboelectric nanogenerator is prepared by a method substantially the same as that in Example 1, except that in S1, F-MXene accounts for 12% of the mass of PVDF-HFP.

[0097] Example 5

[0098] A fog water collection and environment monitoring device, comprising:

[0099] Copper electrodes, serving as a supporting substrate;

[0100] F-MXene / fluorinated polymer nanofiber membrane, disposed on one side of the copper electrode;

[0101] a copper sheet, locally disposed on a side of the F-MXene / fluorinated polymer nanofiber membrane away from the copper electrode and located at the collecting end of the F-MXene / fluorinated polymer nanofiber membrane, the copper sheet being electrically connected to the copper electrode via a wire, and an electrometer being connected therebetween;

[0102] Wherein, the top electrode only covers a portion of the fiber membrane, and a hydrophilic point array is formed by in-situ polymerization of dopamine in the exposed area of ​​the fiber membrane not covered by the top electrode; the fiber membrane is the F-MXene / fluorinated polymer nanofiber membrane described in the first aspect;

[0103] The mist water collection and environment monitoring device is arranged to be inclined relative to the horizontal plane, with an inclination angle of 60°.

[0104] The preparation method of the fog water collection and environment monitoring device of Example 5 comprises the following steps:

[0105] P1. Preparation of composite spinning solution: F-MXene powder was added to a mixed solvent of DMF and acetone in a volume ratio of 6:4. After ultrasonic vibration to uniformly disperse it, PVDF-HFP powder was added to the resulting mixed solution. The mixture was magnetically stirred at a constant temperature of 60°C for 4 hours to obtain a composite spinning solution. The PVDF-HFP content in the composite spinning solution was controlled to be 14 wt% and the F-MXene content was 9% by weight of the PVDF-HFP.

[0106] P2. Preparation of nanofiber membrane: The composite spinning solution was loaded into an electrospinning apparatus. The electrospinning process parameters were set as follows: spinning voltage of 18 kV, receiving distance of 15 cm, micropump speed of 1.0 mL / h, and receiving device speed of 300 rpm. Electrospinning was performed and the nanofibers were deposited onto a collecting drum. The spinning time was controlled to 3 h to obtain an F-MXene / PVDF-HFP nanofiber membrane.

[0107] P3. Preparation of fog water collection material: The F-MXene / PVDF-HFP nanofiber membrane was cut into a size of 5cm×7cm, and a hydrophilic area (hydrophilic point array) was prepared on its 5cm×5cm surface. Under standard environmental conditions (25°C, 55% relative humidity), 20μL of dichloromethane (DCM) was first added to the nanofiber membrane using a pipette. Subsequently, a dopamine droplet containing tris(hydroxymethyl)aminomethane hydrochloride (dopamine concentration was 8g / L) with a volume of 2μL was added above the DCM liquid surface. After the organic solvent was completely evaporated and dopamine completed oxidative self-polymerization, a fog water collection material (F-MXene / PVDF-HFP@PDA) with a single hydrophilic point diameter of 1.88mm, a hydrophilic point distribution matrix of 6×6, and a hydrophilic point edge spacing of 5.5mm was obtained. After cleaning and drying, a black hydrophilic polydopamine pattern was obtained on the surface of the hydrophobic substrate.

[0108] P4. Construction of a fog water collection and power generation device: Cut a copper sheet into 5cm×7cm size and stick it on an acrylic plate as a back electrode, i.e., a copper electrode. Then place the fog water collection material on the copper electrode, and stick a 0.5cm×5cm copper sheet on the bottom of its upper surface as a top electrode. Use conductive tape to stick the wire on the copper sheet and the copper electrode, and connect the other end to the electrometer to obtain a fog water collection and environmental monitoring device. The angle between the surface of the fog water collection and environmental monitoring device and the horizontal plane is 60°.

[0109] During the test, the fog water collection and environmental monitoring device was placed in a sealed box, a humidifier was used to introduce fog, fog water was collected by a collection vessel, and an electrometer was used to measure the electrical signal. The fog water collection principle of the fog water collection and power generation device and the solid-liquid friction nanogenerator are shown in the figure. Figure 6As shown in the figure. In the dynamic flow of fog, the hydrophilic areas constructed on the nanofiber membrane rapidly capture water molecules. When water droplets in the hydrophilic areas are large enough, gravity can overcome the adhesion between the hydrophilic areas and water and allow them to move. The strong water repellency of the hydrophobic areas then causes the water to fall off the surface of the collection device under gravity and be collected. During the fog water collection process, the size of the hydrophilic areas is related to the volume of the formed droplets and the force between the droplets and the membrane, while the distribution of the hydrophobic areas affects the speed at which the droplets slide off. The hydrophilic and hydrophobic areas work together to form and fall the droplets, which is a macroscopic expression of the water collection mechanism. During fog water collection, the droplets condensed on the hydrophilic areas slide on the nanofiber membrane surface due to gravitational potential energy, generating triboelectric charges, which in turn generate electrical signals and energy. The basic principle is still that of a triboelectric nanogenerator, but the friction layers are the water droplets and the hydrophobic surface of the nanofiber membrane, making it a liquid-solid triboelectric nanogenerator. The charge transfer caused by friction generates a voltage between the electrodes and a current in the circuit, thereby monitoring the aggregation and flow state of the droplets on the membrane surface.

[0110] Figure 7 The surface morphology SEM images of the F-MXene / PVDF-HFP nanofiber membrane in Example 5 before and after the hydrophilic point array is formed by in-situ polymerization of dopamine; wherein, (a) is the surface morphology SEM image before the hydrophilic point array is formed by in-situ polymerization of dopamine, and (b) is the surface morphology SEM image after the hydrophilic point array is formed by in-situ polymerization of dopamine. Figure 7 As can be seen in the figure, the surface of the fiber without dopamine treatment is smooth, while the fiber after dopamine deposition shows a significant morphological change. Dopamine forms a non-uniform, blocky coating on the fiber surface. This deposition process not only changes the surface morphology of the fiber, but also leads to a significant hydrophilicity in this area.

[0111] Figure 8 The following graphs show the surface water contact angle data for the F-MXene / PVDF-HFP nanofiber membrane in Example 5 before and after the in-situ polymerization of dopamine to form a hydrophilic puncture array. (a) shows the water contact angle data before the in-situ polymerization of dopamine, and (b) shows the water contact angle data after the in-situ polymerization of dopamine. Before PDA deposition, the water contact angle in the hydrophobic region was 146.4°. After PDA deposition, the water contact angle on the fiber surface dropped to 24.5°, indicating hydrophilic properties. This successfully fabricated a biomimetic hydrophilic-hydrophobic interphase surface.

[0112] Comparative Example 1

[0113] A friction nanogenerator includes a positive friction layer, a negative friction layer, a negative friction layer electrode, and an external circuit. The negative friction layer is attached to the negative friction layer electrode. The positive friction layer and the negative friction layer are positioned opposite to each other and can contact and separate from each other. The positive friction layer is copper foil, the negative friction layer is a MXene / PVDF-HFP nanofiber membrane, and the negative friction layer electrode is a copper sheet.

[0114] The preparation method of the triboelectric nanogenerator of Comparative Example 1 comprises the following steps:

[0115] S1. Preparation of composite spinning solution: Monolayer MXene powder was added to a mixed solvent of DMF and acetone in a volume ratio of 6:4. After ultrasonic vibration to uniformly disperse it, PVDF-HFP powder was added to the obtained mixed solution. The mixture was magnetically stirred at a constant temperature of 60°C for 4 hours to obtain a composite spinning solution. The PVDF-HFP content in the composite spinning solution was controlled to be 14 wt% and the MXene content was 3% by weight of the PVDF-HFP.

[0116] S2. Preparation of nanofiber membrane: The composite spinning solution was loaded into an electrospinning apparatus. The electrospinning process parameters were set as follows: spinning voltage of 18 kV, receiving distance of 15 cm, micropump speed of 1.0 mL / h, and receiving device speed of 300 rpm. Electrospinning was performed and the nanofibers were deposited onto a collecting drum. The spinning time was controlled to 3 h to obtain a MXene / PVDF-HFP nanofiber membrane.

[0117] S3. Preparation of a Moisture-Resistant Triboelectric Nanogenerator: A single-electrode, moisture-resistant triboelectric nanogenerator was prepared using a MXene / PVDF-HFP nanofiber membrane as the negative friction layer. Copper foil was used as the positive friction layer, a copper sheet as the negative friction layer electrode, and a copper wire as the conductor. The copper sheet was cut into 5cm x 5cm pieces and attached to an acrylic plate. The MXene / PVDF-HFP nanofiber membrane was then cut into 5cm x 5cm pieces and placed on a copper sheet of the same size. Conductive tape was used to attach the copper wire between the nanofiber membrane and the copper sheet to create the triboelectric nanogenerator.

[0118] Comparative Example 2

[0119] A triboelectric nanogenerator, the preparation method of which is basically the same as that of Comparative Example 1, except that: in S1, MXene accounts for 6% of the mass of PVDF-HFP.

[0120] Comparative Example 3

[0121] A triboelectric nanogenerator, the preparation method of which is basically the same as that of Comparative Example 1, except that: in S1, MXene accounts for 9% of the mass of PVDF-HFP.

[0122] Comparative Example 4

[0123] A triboelectric nanogenerator, the preparation method of which is basically the same as that of Comparative Example 1, except that: in S1, MXene accounts for 12% of the mass of PVDF-HFP.

[0124] Comparative Example 5

[0125] A friction nanogenerator includes a positive friction layer, a negative friction layer, a negative friction layer electrode, and an external circuit. The negative friction layer is attached to the negative friction layer electrode. The positive friction layer and the negative friction layer are positioned opposite to each other and can contact and separate from each other. The positive friction layer is copper foil, the negative friction layer is PVDF-HFP nanofiber membrane, and the negative friction layer electrode is a copper sheet.

[0126] The preparation method of the triboelectric nanogenerator of Comparative Example 5 comprises the following steps:

[0127] S1. Preparation of spinning solution: PVDF-HFP powder was added to a mixed solvent of DMF and acetone in a volume ratio of 6:4, and ultrasonically dispersed to obtain a uniform dispersion. The mixture was then magnetically stirred at a constant temperature of 60°C for 4 hours to obtain a spinning solution. The PVDF-HFP content in the spinning solution was controlled to be 14 wt%;

[0128] S2. Preparation of nanofiber membrane: The spinning solution was loaded into an electrospinning apparatus, and the electrospinning process parameters were set as follows: spinning voltage of 18 kV, receiving distance of 15 cm, micropump speed of 1.0 mL / h, and receiving device speed of 300 rpm. Electrospinning was performed, and the nanofibers were deposited onto a collecting drum. The spinning time was controlled to 3 h to obtain a PVDF-HFP nanofiber membrane.

[0129] S3. Preparation of a triboelectric nanogenerator: A single-electrode triboelectric nanogenerator was prepared using a PVDF-HFP nanofiber membrane as the negative friction layer. Copper foil was used as the positive friction layer, a copper sheet was used as the negative friction layer electrode, and copper wire was used as the conductor. The copper sheet was cut into 5cm x 5cm pieces and attached to an acrylic plate. The PVDF-HFP nanofiber membrane was then cut into 5cm x 5cm pieces and placed on a copper sheet of the same size. Conductive tape was used to affix the copper wire between the nanofiber membrane and the copper sheet to create the triboelectric nanogenerator.

[0130] Figure 9These are the SEM images and fiber diameter distribution diagrams of the F-MXene / PVDF-HFP nanofiber membranes in Examples 1-4; wherein, (a) is the SEM image of Example 1, (b) is the fiber diameter distribution diagram of Example 1, (c) is the SEM image of Example 2, (d) is the fiber diameter distribution diagram of Example 2, (e) is the SEM image of Example 3, (f) is the fiber diameter distribution diagram of Example 3, (g) is the SEM image of Example 4, and (h) is the fiber diameter distribution diagram of Example 4. Figure 10 The SEM images and fiber diameter distribution diagrams of the MXene / PVDF-HFP nanofiber membranes in Comparative Examples 1-4 are shown; wherein, (a) is the SEM image of Comparative Example 1, (b) is the fiber diameter distribution diagram of Comparative Example 1, (c) is the SEM image of Comparative Example 2, (d) is the fiber diameter distribution diagram of Comparative Example 2, (e) is the SEM image of Comparative Example 3, (f) is the fiber diameter distribution diagram of Comparative Example 3, (g) is the SEM image of Comparative Example 4, and (h) is the fiber diameter distribution diagram of Comparative Example 4. Figure 9 and Figure 10 By comparison, it can be seen that the F-MXene / PVDF-HFP nanofiber membranes in Examples 1-4 and the MXene / PVDF-HFP nanofiber membranes in Comparative Examples 1-4 are well formed, and F-MXene and MXene are evenly distributed in the nanofiber membranes.

[0131] Figure 11 The water contact angle data of F-MXene / PVDF-HFP nanofiber membranes in Examples 1-4, MXene / PVDF-HFP nanofiber membranes in Comparative Examples 1-4, and PVDF-HFP nanofiber membranes in Comparative Example 5 are shown. Figure 11 It can be seen that the PVDF-HFP nanofiber membrane in comparative example 5 itself has good hydrophobic properties, and the contact angle is maintained at 142.42°, while the hydrophobic properties of the MXene / PVDF-HFP nanofiber membranes in comparative examples 1-4 decrease, and the contact angle gradually decreases with the increase of the MXene content. This is because the MXene surface has hydrophilic groups such as -OH and -O, which show good hydrophilicity, resulting in a decrease in the hydrophobic properties of the nanofiber membrane. In a high-humidity environment, the surface charge is easily dissipated, which is not conducive to triboelectric power generation output; the contact angle of the F-MXene / PVDF-HFP nanofiber membrane in Examples 1-4 increases with the increase of the F-MXene doping content, and the hydrophobic properties of the nanofiber membrane are improved. This is because the F-MXene surface is grafted with a long fluoroalkyl chain, has a large number of F groups, and consumes a large amount of -OH in the reaction, so that its surface water contact state changes from hydrophilic to hydrophobic. Therefore, the hydrophobic property of the nanofiber membrane is improved, which is conducive to maintaining the surface charge transfer efficiency in a humid environment, thereby maintaining the triboelectric power generation performance.

[0132] Test Example 1

[0133] The electrical signal output effect of the moisture-resistant friction nanogenerators prepared in Examples 1-4 and the friction nanogenerators prepared in Comparative Examples 1-5 were tested, and the parameters were set as follows: contact distance of 4 mm, contact pressure of 10 N and contact frequency of 2 Hz; a graphic sampling multimeter and a high resistance / low current electrometer were used to perform open circuit voltage, short circuit current and transfer charge tests on the moisture-resistant friction nanogenerators prepared in Examples 1-4 and the friction nanogenerators prepared in Comparative Examples 1-5.

[0134] Figure 12 The open circuit voltage, short circuit current and transfer charge spectra of the moisture-resistant triboelectric nanogenerators prepared in Examples 1-4 and Comparative Examples 1-5 were measured at an ambient humidity of 50% RH; wherein, (a) is the open circuit voltage spectra of Comparative Examples 1-5, (b) is the short circuit current spectra of Comparative Examples 1-5, (c) is the transfer charge spectra of Comparative Examples 1-5, (d) is the open circuit voltage spectra of Examples 1-4 and Comparative Example 5, (e) is the short circuit current spectra of Examples 1-4 and Comparative Example 5, and (f) is the transfer charge spectra of Examples 1-4 and Comparative Example 5. Figure 12 It can be seen that compared with Comparative Example 5, that is, the undoped PVDF-HFP nanofiber membrane, the signal output intensity of the doped nanofiber membrane is significantly improved. And with the increase of the doping concentration, the signal intensity is also significantly enhanced. However, when the doping concentration exceeds 9%, the output signal is significantly weakened. This is because doping with MXene or F-MXene will induce a decrease in β-phase crystallization in PVDF-HFP, and too much conductive MXene or F-MXene appears densely in the PVDF matrix, resulting in the formation of a conductive network, thereby promoting leakage conduction and high dielectric loss. In addition, the moisture-resistant friction nanogenerators prepared in Examples 1-4 have greater open circuit voltage, short circuit current and transferred charge than the friction nanogenerators prepared in Comparative Examples 1-4. This is because there are more F elements on the surface of F-MXene, which provides stronger electronegativity and higher hydrophobicity.

[0135] Figure 13 The open circuit voltage, short circuit current and transfer charge spectra of the output of the moisture-resistant friction nanogenerator prepared in Example 3 and the friction nanogenerator prepared in Comparative Example 3 were measured at different humidity levels (RH 50%, RH 60%, RH 70%, and RH 80% from left to right); among them, (a) is the open circuit voltage spectrum of Comparative Example 3, (b) is the short circuit current spectrum of Comparative Example 3, (c) is the transfer charge spectrum of Comparative Example 3, (d) is the open circuit voltage spectrum of Example 3, (e) is the short circuit current spectrum of Example 3, and (f) is the transfer charge spectrum of Example 3. Figure 13It can be seen that the open circuit voltage, short circuit current, and transferred charge of the moisture-resistant triboelectric nanogenerator prepared in Example 3 are greater than those of the triboelectric nanogenerator prepared in Comparative Example 3 at different humidity levels. As the relative humidity increases from 50% to 80%, the open circuit voltage, current density, and transferred charge density of both triboelectric nanogenerators show a decreasing trend. This is because molecules in high humidity accelerate the dissipation of charge on the fiber membrane surface, reducing the potential difference between the electrodes. The triboelectric output voltage of the moisture-resistant triboelectric nanogenerator prepared in Example 3 decreased by 18% at 80% relative humidity compared to 50% relative humidity, while the triboelectric output voltage of the triboelectric nanogenerator prepared in Comparative Example 3 decreased by 34% at 80% relative humidity compared to 50% relative humidity. The moisture-resistant triboelectric nanogenerator prepared in Example 3 can maintain a higher triboelectric output at high humidity. This is because the MXene surface has a large number of -OH hydrophilic groups, which leads to a decrease in the hydrophobicity of the fiber membrane, as shown in the above tests. Therefore, it is easier to adsorb water molecules, resulting in charge dissipation. In the moisture-resistant triboelectric nanogenerator prepared in Example 3, since F-MXene is connected with a large number of F groups and the nanofiber membrane is made of hydrophobic polymer materials, the overall hydrophobicity is better, water molecules are not easily attached to the surface, and a higher triboelectric output can be maintained in a high humidity environment.

[0136] Figure 14 The moisture-resistant friction nanogenerator prepared in Example 3 and the friction nanogenerator prepared in Comparative Example 3 were treated with different pH solutions (pH values ​​from left to right are 0, 3, 6, 8, 11, and 14, respectively) and the output open circuit voltage, short circuit current, and transfer charge spectra were measured at an ambient humidity of 50% RH; wherein, (a) is the open circuit voltage spectrum of Comparative Example 3, (b) is the short circuit current spectrum of Comparative Example 3, (c) is the transfer charge spectrum of Comparative Example 3, (d) is the open circuit voltage spectrum of Example 3, (e) is the short circuit current spectrum of Example 3, and (f) is the transfer charge spectrum of Example 3. The treatment process is to prepare different pH solutions (acidic substance HCl, alkaline substance NaOH), immerse the nanofiber membrane for 2 hours, clean and dry it, and then assemble the friction nanogenerator. The friction power generation output was recorded under the same parameters to explore the acid and alkali resistance of the friction nanogenerator. Figure 14As can be seen from the figure, the triboelectric output of the moisture-resistant triboelectric nanogenerator prepared in Example 3 after acid and alkali treatment is higher than that of the triboelectric nanogenerator prepared in Comparative Example 3 in terms of open-circuit voltage, short-circuit current, and transferred charge. Treatment with alkaline solutions has little effect on triboelectric performance, while treatment with acidic solutions has a greater impact. In particular, the voltage output of the triboelectric nanogenerator prepared in Comparative Example 3 decreased by 55% after treatment with an acid solution at pH 0, while the voltage output of the moisture-resistant triboelectric nanogenerator prepared in Example 3 only decreased by 14.8% under the same conditions. PVDF-HFP itself has good acid and alkali resistance, so the change in the triboelectric nanogenerator output performance is caused by the doping material. Under alkaline conditions, hydroxide ions react with the -OH terminal groups of MXene, causing them to deprotonate and form less stable -O- groups. Under acidic conditions, the oxidation rate of MXene is higher due to the increased reactivity of protons, ultimately leading to material degradation. Furthermore, excessively acidic conditions can lead to an increase in surface defects, which serve as reactive sites for oxidation, making the surface more susceptible to oxidation. Since a large number of -OH groups on the surface of F-MXene have reacted with long fluoroalkyl chains, it has good antioxidant properties even under acidic conditions. The nanofiber membrane doped with F-MXene still maintains excellent triboelectric output after being treated with acidic solution.

[0137] Figure 15 The open circuit voltage spectra of the output of the moisture-resistant triboelectric nanogenerator prepared in Example 3 and the triboelectric nanogenerator prepared in Comparative Example 3 were measured after being placed in a high humidity environment (80% RH) for different time periods (0 days, 25 days, 50 days, and 75 days from left to right); (a) is the open circuit voltage spectrum of the triboelectric nanogenerator prepared in Comparative Example 3, and (b) is the open circuit voltage spectrum of the moisture-resistant triboelectric nanogenerator prepared in Example 3. Figure 15 It can be seen that the open circuit voltage of the friction nanogenerator prepared in Comparative Example 3 dropped significantly after being placed in a high humidity environment for 0-75 days, especially on the 75th day, its open circuit voltage dropped from the initial 243V to 55V, which is consistent with the output voltage of the friction nanogenerator assembled with pure PVDF-HFP fiber membrane, indicating that the doped MXene has been completely oxidized and has lost its effect on triboelectric enhancement; the friction voltage of the moisture-resistant friction nanogenerator prepared in Example 3 only decreased slightly after being placed in a high humidity environment, and on the 75th day, the friction voltage still maintained 94.4% of the original, showing long-term stable output performance in a high humidity environment.

[0138] Test Example 2

[0139] The fog water collection and environmental monitoring device prepared in Example 5 was subjected to triboelectric output and environmental monitoring tests under different environments.

[0140] Figure 16 The water collection efficiency and triboelectric output spectrum of the mist water collection and environmental monitoring device prepared in Example 5 at different mist flow rates (60, 120, 180, 240, 300 mL / h from left to right); (a) is the water collection efficiency data graph at different mist flow rates, and (b) is the triboelectric output voltage signal graph at different mist flow rates. Figure 16 It can be seen that the mist water collection and environmental monitoring device prepared in Example 5 has obvious mist water collection effect at different mist flow rates. The water collection efficiency increases with the increase of mist flow rate. As the mist flow rate increases from 60 mL / h to 300 mL / h, the water collection efficiency increases from 1.239 mg·cm -2 min -1 Increased to 5.306 mg·cm -2 min -1 The increase in water collection efficiency increased the frequency of transient voltage generated by the fog collection and environmental monitoring device, while the peak voltage did not change significantly. This suggests that the fog flow rate only affects the speed at which fog water aggregates into droplets on the hydrophobic surface during collection. As the fog flow rate increases, the fog is more likely to aggregate into small droplets and slide off, increasing the friction frequency between the droplets and the membrane surface. Therefore, the ambient fog flow rate can be monitored by the frequency of the triboelectric output signal.

[0141] Figure 17 The triboelectric output voltage spectrum, pH-voltage fitting curve, and schematic diagram of the effect of ion adsorption on surface charge distribution of the fog water collection and environmental monitoring device prepared in Example 5 under different pH fog water (pH from left to right are 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7); (a) is the triboelectric output voltage spectrum, (b) is the pH-voltage fitting curve, and (c) is a schematic diagram of the effect of ion adsorption on surface charge distribution. Figure 17 As can be seen in (a), the pH of the mist water has a great influence on the output voltage of triboelectric generation. As the pH of the mist water decreases, the output voltage gradually decreases from 2.357V to 1.004V. That is, the stronger the acidity of the mist water, the worse the triboelectric performance. This is because the hydrogen ions (H + ) concentration is high, it will be adsorbed on the solid surface, thereby changing the charge distribution on the solid surface and affecting the efficiency of charge transfer, such as Figure 17 As shown in (c), the increase in ion concentration in the mist water will lead to excessive free ions in the droplets, which will interfere with the transfer of electrons due to the shielding effect. Figure 17 As shown in (b), the triboelectric output voltage increases linearly with the pH of the mist water. By linearly fitting the output voltage, the fitting equation Y = 0.35X + 0.012 (R 2=0.95), showing an excellent linear relationship. Therefore, the mist water collection and environmental monitoring device shows excellent sensitivity to mist water with different pH values ​​(pH=3-7) and has the ability to be applied in self-powered atmospheric acidic gas environment monitoring.

[0142] Figure 18 The fog water collection and environmental monitoring device prepared in Example 5 is placed under different formaldehyde concentrations (from left to right, the concentrations are 0 mg / L, 0.005·10 -3 mg / L, 0.01·10 -3 mg / L, 0.02·10 -3 mg / L, 0.03·10 - 3 mg / L, 0.08·10 -3 mg / L, 0.14·10 -3 mg / L, 0.20·10 -3 mg / L, 0.30·10 -3 mg / L), the triboelectric output voltage spectrum of formaldehyde concentration and voltage, and the schematic diagram of the effect of hydrogen bonds between formaldehyde and water molecules on the surface charge; among them, (a) is the triboelectric output voltage spectrum, (b) is the fitting curve of formaldehyde concentration and voltage, and (c) is the schematic diagram of the effect of hydrogen bonds between formaldehyde and water molecules on the surface charge. Figure 18 As can be seen from (a), the output voltage decreases gradually with the increase of formaldehyde concentration. When the formaldehyde concentration increases from 0 mg / L to 0.30·10 -3 mg / L, the triboelectric output voltage gradually decreased from 2.357V to 0.603V. This is because formaldehyde changes the polarity of water and thus affects the output; Figure 18 As shown in (c), the carbonyl group (C=O) in the formaldehyde molecule can form hydrogen bonds with water molecules, attracting and preventing water molecules from participating in charge transfer at the liquid-solid interface. At the same time, the formation of this hydrogen bond will change the interaction between water molecules, thereby affecting the polar environment of water. The formaldehyde molecule itself is a polar molecule, and its presence will also induce changes in the polarity distribution of surrounding water molecules. It mainly affects the polarity of water through hydrogen bonding and polarity induction, thereby suppressing the amount of triboelectric charge. Figure 18 As shown in (b), the triboelectric output voltage forms a linear relationship with the formaldehyde concentration. Through linear fitting, the fitting equation Y = -6.15X + 2.17 (R 2 =0.91), showing a good linear relationship. The output voltage can be used to detect and calculate the formaldehyde concentration in the mist water, providing a feasible solution for self-powered formaldehyde monitoring in the atmosphere.

[0143] Figure 19 The fog water collection and environmental monitoring device prepared in Example 5 was tested under different PM 2.5Concentration of fog water (from left to right the concentration is 35·10 -3 μg / L, 75·10 -3 μg / L, 115·10 -3 μg / L, 150·10 -3 μg / L, 250·10 -3 μg / L, 500·10 -3 μg / L, 750·10 -3 μg / L, 1000·10 -3 μg / L) triboelectric output voltage spectrum, PM 2.5 The fitting curve of concentration and voltage and the schematic diagram of the working mechanism of the influence of particulate matter on the output of the fog water collection and environmental monitoring device; among them, (a) is the triboelectric output voltage of fog water with different particulate matter contents, (b) is the fitting curve of voltage, and (c) is the schematic diagram of the working mechanism of the influence of particulate matter on the output of the fog water collection and environmental monitoring device. Figure 19 As can be seen from (a), the output voltage gradually increases with the increase of the concentration of particles in the fog water. -3 μg / L increased to 1000·10 -3 μg / L, the output voltage gradually increases from 2.357V to 9.547V. This is because the particles themselves are negatively charged. When particles collide with each other or particles with water, more positive charges will be generated in the droplets. When the droplets approach the Cu electrode, the electrostatic induction between the droplets and the Cu electrode causes electrons to be transferred to the electrode, such as Figure 19 As shown in (c), the voltage output is enhanced. Figure 19 As shown in (b), the triboelectric output voltage increases linearly with the concentration of particulate matter in the mist water. By linearly fitting the output voltage, the fitting equation Y = 7.36X + 1200.43 (R 2 =0.94), showing an excellent linear relationship. Therefore, the fog water collection and environmental monitoring device is effective for fog water with different concentrations of particulate matter (concentration of 35·10 -3 μg / L-1000·10 -3 μg / L) showed excellent sensitivity and had the characteristics of atmospheric PM 2.5 Potential for concentration detection applications.

[0144] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications may be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A moisture-resistant triboelectric nanogenerator, comprising a positive friction layer, a negative friction layer, a negative friction layer electrode, and an external circuit, wherein the negative friction layer is attached to the negative friction layer electrode, and the positive friction layer and the negative friction layer are positioned opposite to each other and can contact and separate from each other, characterized in that: The negative friction layer is a F-MXene / fluorinated polymer nanofiber membrane; The F-MXene / fluorinated polymer nanofiber membrane is prepared by the following method: F-MXene and a fluorinated polymer are dispersed in a solvent, and the obtained composite spinning solution is subjected to electrospinning to obtain the F-MXene / fluorinated polymer nanofiber membrane; the F-MXene is prepared by surface fluorination modification of MXene with fluorinated silane; the fluorinated polymer is selected from one or more of polytetrafluoroethylene, polytetrafluoroethylene-hexafluoropropylene, polytetrafluoroethylene-ethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene and polyvinylidene fluoride-tetrafluoroethylene.

2. The moisture-resistant triboelectric nanogenerator according to claim 1, characterized in that: The content of the fluorine-containing polymer in the composite spinning solution is 14-16 wt %, and the mass of the F-MXene is 3-12% of the mass of the fluorine-containing polymer.

3. The moisture-resistant triboelectric nanogenerator according to claim 1, characterized in that: The process parameters of the electrospinning are: spinning voltage of 16-20 kV, spinning solution flow rate of 0.8-1.0 mL / h, and spinning distance of 13-15 cm.

4. The moisture-resistant triboelectric nanogenerator according to claim 1, characterized in that: The water contact angle of the F-MXene / fluorinated polymer nanofiber membrane is greater than 140°, and the triboelectric output voltage retention rate is greater than 80% in a high humidity environment with a relative humidity of greater than 75%.

5. The moisture-resistant triboelectric nanogenerator according to claim 1, characterized in that: The F-MXene is prepared by the following method: adding MXene to an ethanol solution of 1H,1H,2H,2H-perfluorodecyltriethoxysilane to react to obtain F-MXene.

6. A fog water collection and environment monitoring device, characterized in that: include: a back electrode, serving as a supporting substrate; A fiber membrane is provided on one side of the back electrode; a top electrode, locally disposed on a side of the fiber membrane away from the back electrode and located at a collecting end of the fiber membrane, the top electrode being electrically connected to the back electrode via an external circuit; The top electrode only covers a portion of the fiber membrane, and a hydrophilic point array is formed by in-situ polymerization of dopamine in the exposed area of ​​the fiber membrane not covered by the top electrode; The fiber membrane is an F-MXene / fluorinated polymer nanofiber membrane; the F-MXene / fluorinated polymer nanofiber membrane is prepared by the following method: dispersing F-MXene and a fluorinated polymer in a solvent, and electrospinning the obtained composite spinning solution to obtain the F-MXene / fluorinated polymer nanofiber membrane; the F-MXene is prepared by surface fluorination modification of MXene with fluorinated silane; the fluorinated polymer is selected from one or more of polytetrafluoroethylene, polytetrafluoroethylene-hexafluoropropylene, polytetrafluoroethylene-ethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene and polyvinylidene fluoride-tetrafluoroethylene; The mist water collection and environment monitoring device is arranged to be inclined relative to the horizontal plane, with an inclination angle of 40°-80°.

7. The fog water collection and environment monitoring device according to claim 6, characterized in that: The diameter of the hydrophilic spots in the hydrophilic spot array is 1.5-2.4 mm, and the edge spacing of the hydrophilic spots is 3-8 mm.

8. The fog water collection and environment monitoring device according to claim 6, characterized in that: The specific method of forming a hydrophilic point array by in-situ polymerization of dopamine in the exposed area of ​​the fiber membrane not covered by the top electrode is: adding dichloromethane to the surface of the fiber membrane, and then adding dopamine solution, to cause oxidative self-polymerization to form a hydrophilic point array.

9. The fog water collection and environment monitoring device according to claim 8, characterized in that: The concentration of dopamine in the dopamine solution is 6-12 g / L.

10. Use of the moisture-resistant triboelectric nanogenerator according to claim 1 or the fog water collection and environmental monitoring device according to claim 6 in energy collection and environmental monitoring.

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