Preparation method of flexible inorganic composite nanofiber membrane for water evaporation induced power generation
Flexible inorganic composite nanofiber membranes were prepared by simultaneous multi-needle electrospinning of SiO2 and PMIA solution and high-temperature carbonization treatment, which solved the problems of unstable ion transport and weak photothermal effect of SiO2 material in water evaporation-induced power generation, and realized efficient hydropower cogeneration.
Patent Information
- Application Number
- CN202511005920.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-17
- Publication Date
- 2025-10-28
AI Technical Summary
Existing SiO2 materials suffer from unstable ion transport and weak photothermal effects during water evaporation-induced power generation, resulting in low output power and difficulty in driving electronic devices.
Precursor composite nanofiber membranes were prepared by simultaneous multi-needle electrospinning of SiO2 and PMIA solution, and combined with high-temperature carbonization process to form flexible inorganic composite nanofiber membranes. The SiO2 fibers and PMIA fibers are interwoven and distributed to enhance photothermal effect and ion transport stability.
It improves the photothermal performance and ion transport stability of inorganic composite nanofiber membranes, enhances the driving force of water evaporation, and increases power generation and output potential difference, making it suitable for the field of combined hydropower.
Smart Images
Figure CN120844285A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of new energy conversion, specifically to a method for preparing a flexible inorganic composite nanofiber membrane for water evaporation-induced power generation. Background Art
[0002] According to the sustainable development strategy, utilizing environmentally friendly energy sources to address the current global energy crisis is a trend. Currently developed green energy sources include solar, wind, and geothermal energy. However, considering factors such as geographical influence and cost-effectiveness, effectively utilizing solar energy to convert hydropower into electricity while simultaneously producing clean water holds great promise. In this context, a proposal has emerged to effectively collect solar energy for photothermal conversion, obtaining clean water through evaporation at the solar interface, and then using nanotechnology to simultaneously generate electricity, achieving combined hydropower production, demonstrating even greater potential. Nanogenerators can utilize the interfacial interaction between materials and water molecules to convert mechanical energy into electrical energy. Specifically, liquid or gaseous water molecules directionally drive the migration of hydrated charged particles within the material, directly converting them into electrical energy. Through the water voltaic effect, liquid water molecules move directionally within the micro- and nano-pores of the fiber membrane, driving water evaporation and power generation. When the lower end of the material is submerged in water, the porous fiber membrane spontaneously absorbs water through capillary permeation and hydrophilic functional group hydration, continuously extending upwards and driving the directional movement of ions, thereby generating sustainable electricity. Using water evaporation power as an effective driving force offers prospects and directions for different energy conversion strategies, significantly reducing costs and offering broad application potential. Furthermore, water resources are widely distributed in oceans, lakes, and rivers, representing a typical clean and renewable energy source. They are abundant, easy to extract, and unaffected by external factors such as geographical environment and weather conditions. Moreover, this generator can utilize a wide variety of materials, fully leveraging the advantages of both resources and nanogenerators.
[0003] Currently, there are various types of materials used in the field of combined hydropower. Most porous nanostructure materials can generate electricity through water evaporation, such as porous biofilms, carbon nanotubes, and graphene oxide. However, due to poor mechanical properties and ionic conductivity, their output power is low and they are difficult to drive electronic devices. Silica (SiO2), as a hydropower material that is widely found in nature, is rich in hydrophilic silanol groups -SiOH on its surface. It provides excellent hydrophilicity and can quickly and spontaneously adsorb and wet water molecules. At the same time, it dissociates in the water environment, making the surface electronegative. When in contact with water, cations in the solution are electrostatically attracted and gathered near the solid / liquid interface, while repelling anions, forming a solid / liquid interface double layer. This becomes the core driving force for water evaporation-induced power generation and has been extensively studied by scholars (Vander Heyden, FHJ, et al., Electrokinetic energy conversion efficiency in nanofluidic channels. NanoLetters, 2006.6(10): p.2232-2237.). However, single SiO2 materials suffer from unstable ion transport and weak photothermal effects during water evaporation-induced power generation, which limits their further application. Summary of the Invention
[0004] Based on the above, this invention discloses a method for preparing a flexible inorganic composite nanofiber membrane for water evaporation-induced power generation. The precursor composite nanofiber membrane is prepared by simultaneous multi-needle electrospinning of SiO2 and PMIA solution. SiO2 fibers and PMIA fibers are interwoven and distributed. Combined with a high-temperature carbonization process, PMIA is converted into carbon fibers, forming an inorganic composite nanofiber membrane with a certain degree of flexibility. It is expected that the introduction of PMIA-based carbon materials to form a blend system will optimize the ion transport stability of SiO2 materials and enhance photothermal effects.
[0005] Specifically, electrospun inorganic composite nanofiber membranes possess a certain surface potential, and upon contact with water, a large amount of negative charge accumulates on their surface. Simultaneously, the PMIA uniformly distributed on the fiber membrane, after high-temperature carbonization, increases the specific surface area of the inorganic composite fiber membrane, giving it abundant micro- and nano-pores. Therefore, when the fiber membrane comes into contact with water, an overlapping electrical double layer (EDL) forms at the solid-liquid interface. Water evaporation drives the counterions in the EDL to move directionally along the evaporation force, thus forming a flow potential. Furthermore, the carbonized nanofiber membrane forms carbon fibers within its interior, causing the membrane to noticeably change from white to dark brown. After absorbing water, due to strong interfacial scattering and the interaction of the porous structure, it appears black during operation, enhancing its photothermal effect and improving its ability to absorb and convert light, further absorbing visible and infrared light from sunlight and converting it into heat energy.
[0006] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows:
[0007] A method for preparing a flexible inorganic composite nanofiber membrane for water evaporation-induced power generation includes the following steps:
[0008] (1) Preparation of SiO2 spinning solution: Tetraethyl orthosilicate, deionized water and H2C2O4 are mixed, wherein the mass ratio of tetraethyl orthosilicate to deionized water is 1:0.5 to 1:2.0, and then Si and H2C2O4 are added. + A silicon solution was prepared by adding H2C2O4 at a molar ratio of 1:0.01 to 1:0.10. Then, the silicon solution was mixed with 10wt% PVA solution at a volume ratio of 1:1 to 1:2 and stirred at room temperature to obtain SiO2 spinning solution.
[0009] (2) Preparation of PMIA spinning solution: Based on synchronous multi-needle electrospinning technology, a certain mass fraction of PMIA is dissolved in DMAC, and a uniform and transparent PMIA spinning solution with a mass fraction of 10-15% is obtained by magnetic stirring at room temperature.
[0010] (3) Preparation of precursor composite nanofiber membrane: Based on synchronous multi-needle electrospinning technology, the prepared SiO2 spinning solution and PMIA spinning solution were placed in two different needle tubes respectively. The spinning needles were connected to a high-voltage power supply, and the metal roller was used as the receiving device for nanofibers. The spinning voltage was set at 20-30V and the spinning distance was set at 15-25cm. Finally, the precursor composite nanofiber membrane was obtained.
[0011] (4) Carbonization treatment: The precursor composite nanofiber membrane is placed in a tube carbonization furnace and heated to 500°C at a heating rate of 2-5°C / min under nitrogen atmosphere, and then heated to 500-700°C at a heating rate of 1-2°C / min. After holding at the temperature for 30-60 min, it is naturally cooled to room temperature to finally obtain a flexible inorganic composite nanofiber membrane that can be used for water evaporation-induced power generation.
[0012] Preferably, the mass ratio of tetraethyl orthosilicate to deionized water in step (1) is 1:1, and the Si and H content is... + The molar ratio is 1:0.05; the volume ratio of silicon solution to PVA solution is 1:1.
[0013] Preferably, the PMIA spinning solution in step (2) has a mass fraction of 12%;
[0014] Preferably, the spinning voltage in step (3) is 25KV and the spinning distance is 18cm.
[0015] Preferably, the heating rate in step (4) is to heat to 500°C at a heating rate of 5°C / min, then heat to 600°C at a heating rate of 2°C / min, hold for 60 minutes, and then naturally cool to room temperature.
[0016] Compared with the prior art, the present invention has the following advantages and outstanding effects:
[0017] (1) The prepared inorganic composite nanofiber membrane contains interwoven SiO2 microfibers and PMIA-based carbon nanofibers, forming a unique synergistic mechanism. The SiO2 microfibers are rich in Si-OH groups on their surface, providing excellent hydrophilicity and serving as the core driving force for water evaporation-induced power generation. The PMIA-based carbon nanofibers are electrically neutral and possess excellent light absorption and photothermal conversion performance, effectively increasing the temperature of the composite membrane under sunlight irradiation and achieving efficient interfacial evaporation. Simultaneously, their photothermal effect helps optimize the ion transport stability of the SiO2 material and promotes continuous water transport, ensuring the continuous and stable operation of the SiO2 microfiber water evaporation-induced power generation process.
[0018] (2) The inorganic composite nanofiber membrane prepared by synchronous multi-needle electrospinning technology exhibits a multi-level structure with large specific surface area and high porosity. The large specific surface area provides abundant solid-liquid reaction interfaces, while the high porosity structure ensures a continuous supply of water and rapid vapor dissipation, jointly realizing efficient capillary water transport and evaporation processes. This structural characteristic significantly accelerates the directional flow of cations in the electric double layer and effectively increases the ion concentration gradient, thereby generating a larger output potential difference.
[0019] (3) The preparation method is simple and easy to implement, with strong controllability. It can also be compatible with existing high-speed electrospinning equipment to achieve large-scale preparation, which provides a guarantee for the industrial production and large-scale application of flexible inorganic composite nanofiber membranes for water evaporation-induced power generation. Attached Figure Description
[0020] To clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below.
[0021] Figure 1 This describes the preparation process of flexible inorganic composite nanofiber membranes.
[0022] Figure 2 This is a photograph of a flexible inorganic composite nanofiber membrane.
[0023] Figure 3 This is an electron microscope image of the precursor composite nanofiber membrane observed at 10 kV with a magnification of 3000X.
[0024] Figure 4This is an electron microscope image of a flexible inorganic composite nanofiber membrane observed at 10kV with a magnification of 2000X.
[0025] Figure 5 This is a graph showing the hydrophilic properties of a flexible inorganic composite nanofiber membrane.
[0026] Figure 6 This is a working image of a flexible inorganic composite nanofiber membrane. Detailed Implementation
[0027] The following examples further illustrate the preparation method of the flexible inorganic composite nanofiber membrane for water evaporation-induced power generation provided by the present invention, but these should not be construed as limiting the scope of protection of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are also part of the present invention.
[0028] Example 1
[0029] (1) Preparation of SiO2 spinning solution: Tetraethyl orthosilicate, deionized water and H2C2O4 are mixed, wherein the mass ratio of tetraethyl orthosilicate to deionized water is 1:1, and then Si and H2C2O4 are added. + A silicon solution was prepared by adding H2C2O4 at a molar ratio of 1:0.05. Then, the silicon solution was mixed with 10wt% PVA solution at a volume ratio of 1:1 and stirred at room temperature to obtain SiO2 spinning solution.
[0030] (2) Preparation of PMIA spinning solution: Dissolve a certain mass fraction of PMIA in DMAC and stir magnetically at room temperature to obtain a uniform and transparent PMIA spinning solution with a mass fraction of 12%.
[0031] (3) Preparation of precursor composite nanofiber membrane: Based on synchronous multi-needle electrospinning technology, the prepared SiO2 spinning solution and PMIA spinning solution were placed in two different needle tubes respectively. The spinning needles were connected to a high voltage power supply, and the metal roller was used as the receiving device for nanofibers. The spinning voltage was set at 25V and the spinning distance was set at 18cm. Finally, the precursor composite nanofiber membrane was obtained.
[0032] (4) Carbonization treatment: The precursor composite nanofiber membrane was placed in a tube carbonization furnace and heated to 500°C at a heating rate of 5°C / min under nitrogen atmosphere. After holding at the temperature for 60 min, it was naturally cooled to room temperature to finally obtain a flexible inorganic composite nanofiber membrane that can be used for water evaporation-induced power generation.
[0033] Example 2
[0034] (1) Preparation of SiO2 spinning solution: Tetraethyl orthosilicate and deionized water (H2C2O4) are mixed, wherein the mass ratio of tetraethyl orthosilicate to deionized water is 1:1, and then Si and H2C2O4 are added. + A silicon solution was prepared by adding H2C2O4 at a molar ratio of 1:0.05. Then, the silicon solution was mixed with 10wt% PVA solution at a volume ratio of 1:1 and stirred at room temperature to obtain SiO2 spinning solution.
[0035] (2) Preparation of PMIA spinning solution: Dissolve a certain mass fraction of PMIA in DMAC and stir magnetically at room temperature to obtain a uniform and transparent PMIA spinning solution with a mass fraction of 12%.
[0036] (3) Preparation of precursor composite nanofiber membrane: Based on synchronous multi-needle electrospinning technology, the prepared SiO2 spinning solution and PMIA spinning solution were placed in two different needle tubes respectively. The spinning needles were connected to a high voltage power supply, and the metal roller was used as the receiving device for nanofibers. The spinning voltage was set at 25V and the spinning distance was set at 18cm. Finally, the precursor composite nanofiber membrane was obtained.
[0037] (4) Carbonization treatment: The precursor composite nanofiber membrane was placed in a tube carbonization furnace and heated to 500°C at a heating rate of 5°C / min under nitrogen atmosphere, and then heated to 600°C at a heating rate of 2°C / min. After holding at the temperature for 60 min, it was naturally cooled to room temperature to finally obtain a flexible inorganic composite nanofiber membrane that can be used for water evaporation-induced power generation.
[0038] Example 3
[0039] (1) Preparation of SiO2 spinning solution: Tetraethyl orthosilicate, deionized water and H2C2O4 are mixed, wherein the mass ratio of tetraethyl orthosilicate to deionized water is 1:1, and then Si and H2C2O4 are added. + A silicon solution was prepared by adding H2C2O4 at a molar ratio of 1:0.05. Then, the silicon solution was mixed with 10wt% PVA solution at a volume ratio of 1:1 and stirred at room temperature to obtain SiO2 spinning solution.
[0040] (2) Preparation of PMIA spinning solution: Dissolve a certain mass fraction of PMIA in DMAC and stir magnetically at room temperature to obtain a uniform and transparent PMIA spinning solution with a mass fraction of 12%.
[0041] (3) Preparation of precursor composite nanofiber membrane: Based on synchronous multi-needle electrospinning technology, the prepared SiO2 spinning solution and PMIA spinning solution were placed in two different needle tubes respectively. The spinning needles were connected to a high voltage power supply, and the metal roller was used as the receiving device for nanofibers. The spinning voltage was set at 25V and the spinning distance was set at 18cm. Finally, the precursor composite nanofiber membrane was obtained.
[0042] (4) Carbonization treatment: The precursor composite nanofiber membrane was placed in a tube carbonization furnace and heated to 500°C at a heating rate of 5°C / min under nitrogen atmosphere, and then heated to 700°C at a heating rate of 2°C / min. After holding at the temperature for 60 min, it was naturally cooled to room temperature to finally obtain a flexible inorganic composite nanofiber membrane that can be used for water evaporation-induced power generation.
[0043] Comparative Example 1
[0044] (1) Preparation of SiO2 spinning solution: Tetraethyl orthosilicate, deionized water and H2C2O4 are mixed, wherein the mass ratio of tetraethyl orthosilicate to deionized water is 1:1, and then Si and H2C2O4 are added. + A silicon solution was prepared by adding H2C2O4 at a molar ratio of 1:0.05. Then, the silicon solution was mixed with 10wt% PVA solution at a volume ratio of 1:1 and stirred at room temperature to obtain SiO2 spinning solution.
[0045] (2) Preparation of SiO2 microfiber membrane: The prepared SiO2 spinning solution was placed in the spinning needle tube, the spinning needle was connected to the high voltage power supply, the metal roller was used as the receiving device for nanofibers, the spinning voltage was set at 25V, the spinning distance was set at 18cm, and finally the SiO2 microfiber membrane was obtained.
[0046] (3) Carbonization treatment: The prepared SiO2 microfiber membrane is placed in a tube carbonization furnace and heated to 500°C at a heating rate of 5°C / min under nitrogen atmosphere, and then heated to 600°C at a heating rate of 2°C / min. After holding at the temperature for 60 min, it is naturally cooled to room temperature to finally obtain a flexible SiO2 microfiber membrane that can be used for water evaporation-induced power generation.
[0047] Comparative Example 2
[0048] (1) Preparation of SiO2 spinning solution: Tetraethyl orthosilicate, deionized water and H2C2O4 are mixed, wherein the mass ratio of tetraethyl orthosilicate to deionized water is 1:1. Then, H2C2O4 is added with a Si to H+ molar ratio of 1:0.05 to prepare a silicon solution. Then, the silicon solution is mixed with 10wt% PVA solution at a volume ratio of 1:1 and stirred at room temperature to obtain SiO2 spinning solution.
[0049] (2) Preparation of PMIA spinning solution: Dissolve a certain mass fraction of PMIA in DMAC and stir magnetically at room temperature to obtain a uniform and transparent PMIA spinning solution with a mass fraction of 12%.
[0050] (3) Preparation of SiO2 / PMIA composite nanofiber membrane: Based on synchronous multi-needle electrospinning technology, the prepared SiO2 spinning solution and PMIA spinning solution were placed in two different needle tubes respectively. The spinning needles were connected to a high-voltage power supply, and the metal roller was used as the receiving device for nanofibers. The spinning voltage was set at 25V and the spinning distance was set at 18cm. Finally, the SiO2 / PMIA composite nanofiber membrane was obtained.
[0051] Electricity generated (mV) Light absorption rate (%) Example 1 298.7 75 Example 2 330.6 90 Example 3 313.2 95 Comparative Example 1 283.4 58 Comparative Example 2 220.6 5.6
[0052] Comparative Example 1 demonstrates that the pure SiO2 microfiber membrane itself has a negative surface charge, enabling the formation of an electric double layer within the channel and generating a flow potential. Comparative Example 2 shows that compositing PMIA nanofibers onto the pure SiO2 microfiber membrane makes the membrane more compact, reducing its power generation. Through these comparative examples and embodiments, it can be concluded that the carbonized composite nanofiber membrane exhibits increased porosity and enhanced photothermal effect, thereby affecting the evaporation rate and increasing power generation. Examples 1-3 conclude that as the carbonization temperature increases, the degree of carbonization of the fiber membrane deepens, and the light absorption rate significantly improves; however, higher carbonization temperatures increase the brittleness of the fiber membrane, affecting its power generation output performance. When the carbonization temperature is 600℃, not only is the morphology of the fiber membrane preserved, but it also possesses superior photothermal effect, promoting water transport and enhancing the generation of flow potential.
Claims
1. A method for preparing a flexible inorganic composite nanofiber membrane for water evaporation-induced power generation, comprising the following steps: (1) Preparation of silica (SiO2) spinning solution: Tetraethyl orthosilicate and deionized water are mixed at a mass ratio of 1:0.5 to 1:2.0, and then Si and H are added. + Oxalic acid (H2C2O4) was added at a molar ratio of 1:0.01 to 1:0.10 to prepare a silicon solution. Then, the silicon solution was mixed with 10wt% polyvinyl alcohol (PVA) solution at a volume ratio of 1:1 to 1:2 and stirred at room temperature to obtain SiO2 spinning solution. (2) Preparation of poly(m-phenylene isophthalamide) spinning solution: Dissolve a certain mass fraction of PMIA in N,N-dimethylacetamide (DMAC) and stir at room temperature to obtain a uniform and transparent PMIA spinning solution with a mass fraction of 10-15%. (3) Preparation of electrospinning precursor composite nanofiber membrane: Based on synchronous multi-needle electrospinning technology, the prepared SiO2 spinning solution and PMIA spinning solution were placed in two different needle tubes respectively. The proportion of each component in the membrane was controlled by adjusting the number of different needle tubes from 5:1 to 1:
5. The spinning needles were connected to a high-voltage power supply, and the metal roller was used as the receiving device for nanofibers. The spinning voltage was set at 20-30V and the spinning distance was set at 15-25cm. Finally, the precursor composite nanofiber membrane was obtained. (4) Carbonization treatment: The precursor composite nanofiber membrane is placed in a tube carbonization furnace and heated to 500°C at a heating rate of 2-5°C / min under nitrogen atmosphere, and then heated to 600-700°C at a heating rate of 1-2°C / min. After holding at the temperature for 30-60 min, it is naturally cooled to room temperature to finally obtain a flexible inorganic composite nanofiber membrane that can be used for water evaporation-induced power generation. The flexible inorganic composite nanofiber membrane for water evaporation-induced power generation is characterized by the uniform, continuous, and interwoven distribution of SiO2 microfibers and carbon nanofibers formed by PMIA carbonization. The SiO2 microfibers have a diameter of 1-3 μm and are rich in hydrophilic groups -SiOH on their surface, giving them excellent hydrophilic properties. The PMIA-based carbon nanofibers have a diameter of 100-500 nm and a light absorption rate of 88-96% in the visible light range, which can directly improve the evaporation rate. The two components work together to synergistically enhance water transport efficiency. In addition, the nanofiber membrane has a porosity of 85-90% and a Zeta potential of -25 to -30 mV. During the evaporation-induced power generation process, more double electric layers can be formed in its internal channels, thereby improving the flow potential output.