A carbon black / polyacrylonitrile nanofiber membrane, a preparation method and application thereof

Abstract

The present application relates to nanofunctional material and new energy cross technical field, specifically relates to a kind of carbon black / polyacrylonitrile nanofiber membrane and its preparation method and application;Nanofiber membrane is prepared by carbon black and polyacrylonitrile by blending electrospinning method, carbon black nanopowder is dispersed in organic solvent, and carbon black dispersion liquid is obtained by low-temperature ultrasonic treatment;Polyacrylonitrile powder is added to carbon black dispersion liquid and heated stirring, and carbon black / polyacrylonitrile blending spinning liquid is formed, the mass ratio of carbon black and polyacrylonitrile is 3:10;The blending spinning liquid is electrospun, and carbon black / polyacrylonitrile nanofiber membrane is collected;By optimizing the ratio of carbon black and polyacrylonitrile and preparation process, composite nanofiber membrane with efficient photo-thermal conversion water evaporation and significant evaporation-induced power generation performance is successfully prepared, and the synergistic effect of solar-driven fresh water production and power output is realized, which provides core functional materials for efficient and stable solar water and power generation.

Description

Technical Field

[0001] This invention relates to the field of interdisciplinary technology of nanomaterials and new energy, specifically to a carbon black / polyacrylonitrile nanofiber membrane, its preparation method, and its application. Background Technology

[0002] With the global energy crisis and water scarcity becoming increasingly severe, developing sustainable technologies that can simultaneously address energy and freshwater supply has become a research hotspot. Solar energy, as a clean, abundant, and widely distributed renewable energy source, has shown great potential in seawater desalination and water treatment. In recent years, interfacial evaporation technology based on photothermal conversion has attracted widespread attention due to its high energy utilization efficiency. Meanwhile, "evaporation-induced power generation," which utilizes the naturally generated flow potential during water evaporation to generate electricity, has also provided a new approach for distributed energy collection. Integrating these two functions into a single device to achieve solar-driven combined hydropower has significant scientific and application value.

[0003] To achieve efficient solar-hydropower cogeneration, the key lies in developing multifunctional materials that possess both excellent photothermal conversion capabilities and strong evaporation-induced power generation performance. Ideal materials need to have a porous network structure to facilitate rapid water transport, while also possessing abundant surface charge to enhance ion flow and potential difference during evaporation. In recent years, nanofiber materials have been widely explored for constructing such multifunctional platforms due to their high specific surface area, tunable pore structure, and ease of functionalization. By combining photothermal components with fiber-forming polymers, integrated membrane materials that combine light absorption, water transport, and charge separation can be constructed.

[0004] However, existing nanofiber composite membranes still face key challenges when applied to combined hydropower. On the one hand, pursuing high photothermal conversion efficiency often requires the introduction of a high proportion of functional fillers, but this easily leads to severe agglomeration of the fillers in the polymer matrix, which not only disrupts the continuity of the fibers and the mechanical integrity of the membrane, but may also clog pores and hinder effective water transport. On the other hand, evaporation-induced power generation performance is highly dependent on the charge density of the fiber surface and the pore structure of the membrane, while existing technologies lack a systematic control over the synergistic relationship between the content of functional fillers and the interfacial electrical properties and microstructure of the fiber membrane, making it difficult to simultaneously optimize the photothermal evaporation rate and power generation output voltage in the same material system.

[0005] Therefore, there is an urgent need to develop a new type of nanofiber membrane that can effectively enhance its evaporation-induced power generation capacity while ensuring excellent photothermal performance, thereby truly realizing efficient and stable solar-hydropower cogeneration. Summary of the Invention

[0006] To address the aforementioned shortcomings of existing technologies, this invention provides a carbon black / polyacrylonitrile nanofiber membrane, its preparation method, and its application, which can effectively solve the technical problem that existing nanofiber composite membranes are difficult to synergistically optimize photothermal evaporation performance and evaporation-induced power generation performance in the same material system.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides a carbon black / polyacrylonitrile nanofiber membrane, wherein the nanofiber membrane is prepared by a co-spinning method of carbon black and polyacrylonitrile, wherein the mass ratio of carbon black to polyacrylonitrile is 1~5:10.

[0009] Furthermore, the preferred mass ratio of carbon black to polyacrylonitrile is 3:10.

[0010] Furthermore, the nanofiber membrane is used for solar-driven cogeneration, enabling simultaneous photothermal conversion of water evaporation and evaporation-induced power generation.

[0011] Secondly, the present invention also provides a method for preparing a carbon black / polyacrylonitrile nanofiber membrane, the method comprising:

[0012] (1) Carbon black nanopowder is dispersed in an organic solvent and then subjected to low-temperature ultrasonic treatment to obtain a carbon black dispersion;

[0013] (2) Add polyacrylonitrile powder to the carbon black dispersion, and heat and stir to form a carbon black / polyacrylonitrile blend spinning solution;

[0014] (3) Electrospinning the blended spinning solution and collecting the carbon black / polyacrylonitrile nanofiber membrane;

[0015] The mass ratio of the carbon black nanopowder to the polyacrylonitrile powder is 1:10 to 5:10.

[0016] Furthermore, the mass ratio of the carbon black nanopowder to the polyacrylonitrile powder is 3:10.

[0017] Furthermore, in step (1), the ultrasonic treatment time is 10 h-14 h, preferably 12 h, and the dispersion system is cooled by an ice-water bath during ultrasonic treatment.

[0018] Furthermore, in step (2), the heating and stirring temperature is 35℃-45℃, and the stirring time is 6 h-12 h.

[0019] Furthermore, preferably, in step (2), the heating and stirring temperature is 40°C and the stirring time is 8 h.

[0020] Furthermore, in step (3), the electrospinning adopts a configuration of positive and negative electrodes in the same electric field, wherein the spinneret is connected to a positive high voltage power supply and a +15 kV voltage is applied, the receiver is connected to a negative high voltage power supply and a -5 kV voltage is applied, the receiver distance is 12 cm, the flow rate is 0.01 mL / min, and the spinning time is 10 h.

[0021] Thirdly, the present invention also provides a solar-driven cogeneration device prepared from a carbon black / polyacrylonitrile nanofiber membrane as described in the first aspect, characterized in that the device comprises: a carbon black / polyacrylonitrile nanofiber membrane, an aluminum electrode, a carbon electrode, and a bottom polyimide membrane serving as a support and a carrier for the printed electrode.

[0022] Furthermore, the combined hydropower device can simultaneously produce fresh water and electricity using solar energy.

[0023] The technical solution provided by this invention has the following advantages compared with the known prior art:

[0024] 1. This invention obtains a nanofiber membrane with good fiber morphology and pore structure by optimizing the mass ratio of carbon black and polyacrylonitrile and electrospinning technology. The nanofiber membrane with good fiber morphology and pore structure not only ensures good water transport capacity, but also avoids the performance degradation caused by carbon black agglomeration. It solves the technical problem that existing carbon black composite fiber membranes cannot simultaneously achieve efficient photothermal conversion and strong evaporation-induced power generation performance, and realizes the synergistic improvement of water evaporation and power generation performance in solar-driven hydropower cogeneration.

[0025] 2. This invention significantly improves the Zeta potential of the fiber membrane and enhances the evaporation-induced power generation performance by controlling the carbon black content and utilizing the oxygen-containing functional groups on the carbon black surface to increase the negative charge on the fiber surface.

[0026] 3. This invention optimizes the ratio of carbon black to polyacrylonitrile, enabling the nanofiber membrane to maintain high photothermal conversion efficiency while achieving excellent evaporation-induced power generation performance, thus realizing the integration and optimization of combined hydropower functions. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0028] Figure 1The images shown are scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the nanofiber membranes obtained in Examples 1-3 and the comparative examples of the present invention. A1-A2 are SEM images of the pure PAN membrane in the comparative example at different magnifications; A3 is a TEM image of the pure PAN membrane in the comparative example; B1-B2 are SEM images of the CBNF-1 membrane obtained in Example 1 at different magnifications; B3 is a TEM image of the CBNF-1 membrane obtained in Example 1; C1-C2 are SEM images of the CBNF-3 membrane obtained in Example 2 at different magnifications; C3 is a TEM image of the CBNF-3 membrane obtained in Example 2; D1-D2 are SEM images of the CBNF-5 membrane obtained in Example 3 at different magnifications; and D3 is a TEM image of the CBNF-5 membrane obtained in Example 3.

[0029] Figure 2 The figures are statistical distribution diagrams of the fiber diameter of the nanofiber membranes obtained in Examples 1-3 and the comparative examples of the present invention. A is the statistical distribution diagram of the fiber diameter of the pure PAN membrane in the comparative example, B is the statistical distribution diagram of the fiber diameter of the CBNF-1 membrane obtained in Example 1, C is the statistical distribution diagram of the fiber diameter of the CBNF-3 membrane obtained in Example 2, and D is the statistical distribution diagram of the fiber diameter of the CBNF-5 membrane obtained in Example 3.

[0030] Figure 3 These are water contact angle test photos of the membranes in Examples 1–3 and the comparative example of the present invention, wherein (1) is a water contact angle test diagram of the comparative example pure PAN membrane, (2) is a water contact angle test diagram of the CBNF-1 membrane obtained in Example 1, (3) is a water contact angle test diagram of the CBNF-3 membrane obtained in Example 2, and (4) is a water contact angle test diagram of the CBNF-5 membrane obtained in Example 3.

[0031] Figure 4 The solar absorption spectra of nanofiber membranes with different carbon black contents in Examples 1–3 of the present invention and the pure PAN membrane obtained in the comparative example are shown.

[0032] Figure 5 This is a graph showing the surface Zeta potential test results of fiber membranes with different carbon black contents according to the present invention;

[0033] Figure 6 This is a comparison chart of the water evaporation rate and output voltage of the membranes prepared in Examples 1-3 of the present invention under one day of sunlight. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0035] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail. The terms “comprising,” “including,” “having,” “containing,” etc., as used herein are open-ended terms, meaning that they include but are not limited to. Unless the context clearly indicates otherwise, the expressions “a” and “an” as used herein include plural references. It should be noted that “first,” “second,” etc., are used merely for convenience of description and distinction and should not be construed as indicating or implying relative importance. The term “about” as used herein indicates a range of ±20% of the following numerical value. In some embodiments, the term “about” indicates a range of ±10% of the following numerical value. In some embodiments, the term “about” indicates a range of ±5% of the following numerical value. The invention is further described below with reference to embodiments.

[0036] Example: Refer to Figures 1 to 6 .

[0037] The main objective of this invention is to address the critical issue of the difficulty in synergistically optimizing the photothermal performance and evaporation-induced power generation performance of existing carbon black composite fiber membranes in solar-driven hydropower cogeneration applications. This invention proposes a material design and preparation strategy that combines high-efficiency photothermal conversion with high flow potential output. Specifically, by constructing a carbon black / polyacrylonitrile blend electrospinning system, the influence of carbon black content on fiber structure (such as fiber diameter and porosity) and interfacial electrical properties (Zeta potential) is systematically controlled, thereby achieving synergistic enhancement of the evaporation and charge transport processes. This invention not only focuses on improving photothermal evaporation efficiency but also incorporates evaporation-induced power generation performance into the optimization scope, overcoming the shortcomings of single-performance optimization in existing technologies. Furthermore, through quantitative structure-activity relationship analysis, this technology clarifies that the optimal mass ratio of carbon black to polyacrylonitrile is 3:10. At this ratio, the prepared nanofiber membrane can simultaneously achieve high photothermal conversion efficiency and high evaporation-induced power generation performance, thus avoiding the trial-and-error costs associated with traditional empirical ratios and improving the predictability and repeatability of material design. This objective not only serves the development of efficient integrated seawater desalination and power generation devices, but also provides a theoretical basis for the rational design of multifunctional nanofiber membrane materials.

[0038] According to the electric double layer (EDL) overlap theory, the power generation performance (flow potential) of nanofiber membranes mainly depends on the zeta potential of the nanochannel surface inside the fiber membrane and the continuous water transport driven by capillary action. The higher the zeta potential, the stronger the flow potential effect. Experiments showed that with the increase of carbon black content, the zeta potential of the fibers exhibited a trend of first increasing and then decreasing. This is because the carbon black surface contains oxygen-containing functional groups, which increases the negative charge on the fiber surface, thus increasing the zeta potential of the carbon black / polyacrylonitrile fiber membrane. However, excessively high carbon black content can lead to severe agglomeration inside the fibers, reducing the number of exposed functional groups. In addition, since the fiber diameter increases with increasing carbon black content, the internal nanochannels decrease with increasing fiber diameter, resulting in obstructed water transport and a decrease in continuous water transport capacity. In summary, the power generation performance of carbon black / polyacrylonitrile fiber membranes is affected by both the surface zeta potential and the channel structure (porosity, diameter). Therefore, detailed structure-property analysis of fiber membranes with different carbon black contents is beneficial for preparing carbon black / polyacrylonitrile fiber membranes that can achieve efficient cogeneration of hydropower.

[0039] Example 1

[0040] This embodiment provides an implementation method for preparing carbon black / polyacrylonitrile nanofiber membranes, as detailed below:

[0041] Accurately weigh 0.1 g of carbon black and add it to 9 ml of N,N-dimethylformamide (DMF). Disperse the carbon black in an ice-water bath using ultrasonication for 12 hours to obtain a carbon black dispersion. Then add 1.0 g of PAN (polyacrylonitrile) powder and stir magnetically at 40°C for 8 hours to obtain a homogeneous carbon black / polyacrylonitrile blend spinning solution.

[0042] The blended spinning solution was electrospun using a configuration of positive and negative electrodes in the same electric field. The spinneret was connected to a positive high-voltage power supply with a +15 kV voltage applied, and the receiver was connected to a negative high-voltage power supply with a -5 kV voltage applied. The receiver distance was 12 cm, the flow rate was 0.01 mL / min, and the spinning time was 10 h, resulting in a CBNF-1 membrane.

[0043] Example 2

[0044] The preparation process in this embodiment is the same as in Example 1, except that the carbon black mass is 0.3 g, and the final product is a CBNF-3 membrane.

[0045] Example 3

[0046] The preparation process in this embodiment is the same as in Example 1, except that the carbon black mass is 0.5 g, and the final product is a CBNF-5 membrane.

[0047] Comparative example (pure PAN film)

[0048] Without adding carbon black, 1.0 g of PAN was dissolved in 9 g of DMF and spun using the same parameters to obtain a pure PAN film.

[0049] Power generation devices were fabricated using fiber membranes of varying mass ratios under the same standard. The devices consisted of a nanofiber membrane, an aluminum electrode, a carbon electrode, and a polyimide substrate serving as a support and carrier for the printed electrodes. Different membrane devices were tested according to the same standard, and the pure water power generation voltage of each nanofiber membrane device was measured in pure water. In the above-mentioned stacked hydroelectric device, the upper layer was a nanofiber membrane. After completely wetting the upper nanofiber membrane with pure water, the voltage output from the two electrodes was measured. Alligator clips were used to clamp one end of a DuPont wire, and the other end of the DuPont wire was connected to a voltmeter to measure the voltage. The test results are as follows.

[0050] Performance testing and data analysis

[0051] The samples obtained in Examples 1-3 and the comparative examples were characterized and tested, and the results are as follows:

[0052] Figure 1 Scanning electron microscope images of the nanofiber membranes obtained in Examples 1-3 and the comparative examples are shown, illustrating the changes in fiber morphology and diameter under different carbon black contents. Figure 2 This is a statistical distribution chart of fiber diameters in fiber membranes with different carbon black contents. Figure 1 and Figure 2 The SEM images and pore sizes show that the CBNF-3 membrane has good fiber morphology, moderate diameter, and a better pore structure than the CBNF-5.

[0053] Figure 3Water contact angle test diagrams of a comparative pure PAN membrane and nanofiber membranes obtained in Examples 1–3 are shown. (1) is the water contact angle test diagram of the comparative pure PAN membrane, (2) is the water contact angle test diagram of the CBNF-1 membrane obtained in Example 1, (3) is the water contact angle test diagram of the CBNF-3 membrane obtained in Example 2, and (4) is the water contact angle test diagram of the CBNF-5 membrane obtained in Example 3. A drop of water is placed on the surface of the material, and its side profile is photographed. The angle (θ) formed at the intersection of the water droplet and the solid surface is the contact angle. The water contact angle test diagrams characterize the wettability / hydrophobicity of different fiber membrane surfaces. As shown in the figure, in the comparative PAN membranes, CA: 19.7 indicates a water contact angle of 19.7°. The water contact angle of the CBNF-1 membrane in Example 1 is 22.3°, the contact angle of the CBNF-3 membrane in Example 2 is 25.1°, and the contact angle of the CBNF-5 membrane in Example 3 is 31.5°. A smaller contact angle indicates a more hydrophilic material surface, better wetting properties, and easier spread of liquids. With increasing carbon black content, the contact angle of the fiber membrane slightly increases. This is because a higher carbon black content leads to more severe carbon black agglomeration, resulting in less uniform carbon black dispersion in the prepared fiber membrane, causing the fibers to become rougher (e.g., ...). Figure 1 As shown in D1) and the diameter increases (as shown in the figure). Figure 2 As shown in the figure, this affects the contact angle.

[0054] Figure 4 The solar absorption spectra of fiber membranes with different carbon black contents and pure PAN membranes are shown. Figure 4 It can be seen that, in terms of light absorption, the light absorption rate of CBNF-3 film is significantly higher than that of CBNF-1 film, but lower than that of CBNF-5 film, and the light absorption efficiency is directly proportional to the carbon black content.

[0055] Figure 5 The graph shows the surface Zeta potential test results of fiber membranes with different carbon black contents. Figure 5 It can be seen that, in terms of Zeta potential, the surface Zeta potential of CBNF-3 is higher than that of CBNF-1 and CBNF-5, showing a trend of first increasing and then decreasing.

[0056] Figure 6 The graph shows a comparison of the water evaporation rate and output voltage of the membranes prepared in Examples 1-3 under one day of sunlight. As can be seen from the graph, in terms of combined water and power generation performance, the CBNF-3 membrane ranks first in both evaporation rate and output voltage, with the best overall performance (evaporation rate 4.11 kg m³ / s). -2 h -1 The optimal output voltage (0.81 V) fully demonstrates the superior effect of the optimal formulation discovered in this invention.

[0057] From Example 1 to Example 3, as the mass ratio of carbon black to polyacrylonitrile increased from 1:10 to 5:10, the average diameter of the fibers significantly increased and the surface became rougher, while the porosity of the fiber membrane decreased accordingly. This is because carbon black increases the conductivity and viscosity of the spinning solution. Simultaneously, the surface zeta potential of the fiber membrane showed a trend of first increasing and then decreasing with increasing carbon black content. This is because the carbon black surface contains oxygen-containing functional groups, which increases the negative charge on the fiber surface, thus increasing the zeta potential of the carbon black / polyacrylonitrile fiber membrane. However, excessively high carbon black content can lead to severe agglomeration within the fibers, reducing the number of exposed functional groups. Furthermore, as the fiber diameter increases with increasing carbon black content, the internal nanochannels decrease, hindering water transport and reducing the continuous water transport capacity. Compared to the zeta potential of the pure polyacrylonitrile membrane, the composite fiber membrane containing carbon black has a higher zeta potential. The introduction of carbon black alters the electrochemical double-layer structure of the fiber / solution interface; therefore, the generation of the flow potential of the carbon black / polyacrylonitrile fiber membrane is mainly dominated by carbon black.

[0058] Based on the above analysis and considering the influence of the electrical double-layer overlap theory on ion transport within nanochannels, this invention determines the optimal mass ratio for synergistic performance of the fiber membrane. When the mass ratio of carbon black to polyacrylonitrile is 3:10, the prepared membrane possesses both high light absorption capacity and a suitable water-carrying pore structure, thus providing an optimal environment for evaporation-induced ion-selective flow. Experiments confirm that this specific ratio membrane (CBNF-3) exhibits a water evaporation rate (4.11 kg m³ / s) under one standard solar irradiation. -2 h -1 Both the output voltage (>0.8 V) and the output voltage are significantly better than those of other ratios (such as CBNF-1 and CBNF-5), achieving synergistic maximization of photothermal and power generation performance.

[0059] This invention, starting from a multi-scale coupling mechanism, achieves synergistic optimization of photothermal and flow potential effects. Theoretically, based on EDL overlap theory, this invention systematically reveals for the first time the dual regulatory mechanism of carbon black content on zeta potential and nanochannel structure, and further clarifies its influence on evaporation-induced power generation performance (initially enhancing then weakening), establishing a relatively complete structure-property relationship model. In terms of practical efficacy, the prepared carbon black / polyacrylonitrile nanofiber membrane, under optimal ratio conditions, can simultaneously achieve efficient solar energy absorption, stable water transport, and enhanced flow potential output, thereby significantly improving the overall energy utilization efficiency of the combined hydropower system. Compared to existing material systems that only emphasize photothermal conversion or a single power generation mechanism, this technology achieves multifunctional synergistic efficiency and has higher engineering application potential. Based on existing electrospinning technology, this invention achieves systematic optimization of functional coupling by introducing a structure-property relationship-guided component regulation strategy.

[0060] From an overall perspective, firstly, at the core mechanism level, the flow potential output is enhanced by controlling the surface electrical properties (Zeta potential) and nanochannel structure of the material. Specifically, for the carbon black / polyacrylonitrile system, the optimal ratio and corresponding structural parameters are the best results obtained through systematic experiments, demonstrating high specificity and irreplaceability. While other conductive fillers (such as graphene, carbon nanotubes, etc.) or other polymer matrix materials can theoretically achieve similar functions, their interfacial interactions, dispersibility, and fiber-forming properties differ significantly, making it difficult to directly replace the present invention without re-optimization. Secondly, regarding the preparation process, blend electrospinning, as a mature technology, can be replaced to some extent by other nanostructure construction methods (such as phase separation, template methods, etc.). However, these methods have limitations in terms of continuity, controllability, and large-scale production, making it difficult to simultaneously meet the present invention's requirements for structural uniformity and functional integration. Therefore, from an engineering implementation perspective, the process route of the present invention has high practical stability. Finally, in terms of functional implementation, this invention emphasizes the synergistic optimization of photothermal evaporation and power generation performance, rather than a single performance improvement. This multi-functional coupling makes this invention difficult to be replaced by a single improvement technology.

[0061] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A carbon black / polyacrylonitrile nanofiber membrane, characterized in that, The nanofiber membrane is prepared by co-spinning carbon black and polyacrylonitrile, wherein the mass ratio of carbon black to polyacrylonitrile is 1~5:

10.

2. The carbon black / polyacrylonitrile nanofiber membrane according to claim 1, characterized in that, The mass ratio of carbon black to polyacrylonitrile is 3:

10.

3. A carbon black / polyacrylonitrile nanofiber membrane according to claim 1 or 2, characterized in that, The nanofiber membrane is used for solar-driven cogeneration, enabling simultaneous photothermal conversion of water evaporation and evaporation-induced power generation.

4. A method for preparing a carbon black / polyacrylonitrile nanofiber membrane, characterized in that the method... include: (1) Carbon black nanopowder is dispersed in an organic solvent and then subjected to low-temperature ultrasonic treatment to obtain a carbon black dispersion; (2) Add polyacrylonitrile powder to the carbon black dispersion, and heat and stir to form a carbon black / polyacrylonitrile blend spinning solution; (3) Electrospinning the blended spinning solution and collecting the carbon black / polyacrylonitrile nanofiber membrane; The mass ratio of the carbon black nanopowder to the polyacrylonitrile powder is (1-5):

10.

5. The method for preparing a carbon black / polyacrylonitrile nanofiber membrane according to claim 4, characterized in that, The mass ratio of the carbon black nanopowder to the polyacrylonitrile powder is 3:

10.

6. The method for preparing a carbon black / polyacrylonitrile nanofiber membrane according to claim 4, characterized in that, In step (1), the ultrasonic treatment time is 6 h-12 h, and the dispersion system is cooled by an ice-water bath during ultrasonic treatment.

7. The method for preparing a carbon black / polyacrylonitrile nanofiber membrane according to claim 4, characterized in that, In step (2), the heating and stirring temperature is 35℃-45℃, and the stirring time is 10 h-14 h.

8. The method for preparing a carbon black / polyacrylonitrile nanofiber membrane according to claim 4, characterized in that, In step (3), the electrospinning adopts the same electric field configuration for positive and negative poles. The spinneret is connected to a positive high voltage power supply and a +15kV voltage is applied. The receiver is connected to a negative high voltage power supply and a -5kV voltage is applied. The receiver distance is 12 cm, the flow rate is 0.01 mL / min, and the spinning time is 10 h.

9. A solar-driven combined hydropower device, characterized in that, The device is a stacked structure, comprising: a carbon black / polyacrylonitrile nanofiber membrane, an aluminum electrode, a carbon electrode, and a bottom polyimide membrane serving as a support and carrier for the printed electrode.

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