A gradient porous core-sheath structure sensing fiber based on gradient-induced phase separation and a preparation method thereof

Abstract

The application discloses a gradient pore core-sheath structure sensing fiber based on gradient-induced phase separation and a preparation method thereof. The sensing fiber is composed of a core layer, an intermediate layer and a sheath layer. The sheath layer forms a gradient pore structure along the radial direction of the sensing fiber, and the pore diameter gradually decreases from the outer surface to the inside. The preparation of the sensing fiber comprises the following steps: the core layer spinning solution, the intermediate layer spinning solution and the sheath layer spinning solution are respectively injected into the inner layer, the intermediate layer and the outer layer channels of the spinneret, extrusion is carried out by using a wet spinning method, and then the obtained nascent fiber is immersed into a tert-butyl alcohol aqueous solution, the fiber is collected and freeze-dried, and the sensing fiber is obtained. The application successfully constructs the gradient pore structure with large pores outside and small pores inside in the fiber sheath layer by regulating the phase separation kinetics through two-step coagulation bath, and the prepared sensing fiber realizes high-sensitivity and rapid detection of CO.

Description

Technical Field

[0001] This invention belongs to the field of new material preparation technology, specifically relating to a self-healing friction layer material, its preparation method, and its application. Background Technology

[0002] Fire is one of the most destructive disasters, threatening life and property. With the increasing complexity of modern building structures, the widespread use of new energy facilities, and the intensive development of underground spaces, the concealment, suddenness, and speed of spread of fires have all significantly increased. Traditional fire monitoring and prevention methods are facing unprecedented challenges. Currently, widely used early fire warning devices mainly include traditional smoke detectors and infrared thermal sensors, which primarily identify fires by monitoring signals such as smoke particles or changes in ambient temperature. However, these technologies have inherent limitations: their physical structures are usually relatively fixed, lacking flexibility in installation and layout; they also heavily rely on a continuous and stable power supply. Once a power outage or unstable power supply occurs, the warning function may fail, thereby reducing system reliability and practical application capabilities.

[0003] To address these challenges, the scientific community has begun focusing on novel nanomaterials and flexible sensing technologies. In recent years, highly sensitive fire early warning sensors based on graphene oxide (GO) or metal-oxide-semiconductor (MOS) have been developed, enabling the detection of early-stage environmental temperature changes during fires through microstructure engineering. For example, some studies have functionalized graphene oxide to improve its sensitivity to subtle temperature fluctuations; others have employed two-dimensional composite systems, such as Ti3C2Tx MXene, to specifically detect characteristic gases released in the early stages of a fire. These intelligent fire early warning sensors significantly outperform traditional technologies in terms of response speed. However, relying solely on a single signal for detection still presents significant challenges to accurate early warning in practical applications.

[0004] Based on the above challenges, different solutions have emerged. For example, flexible fiber-based fire early warning sensors have attracted widespread attention due to their good fit, ease of integration, and adaptability to complex surfaces. However, most fiber sensors currently in use have homogeneous hole structures, which present the following problems when used: (1) The gas transport path inside the fiber is single and long, and the diffusion rate is limited; (2) The utilization rate of internal active sites is low, and the gas adsorption efficiency is insufficient; (3) The sensing response speed is slow and the detection sensitivity is limited.

[0005] Studies have shown that introducing porous structures into the sensing layer can significantly reduce the effective elastic modulus of the material, making it more susceptible to deformation under external forces, thereby greatly improving the sensitivity of the sensor. However, traditional uniform porous structures often face the bottleneck of balancing sensitivity and sensing range: while high porosity can improve initial sensitivity, the pores will quickly close and reach saturation under relatively low pressure, resulting in an extremely limited detection range; conversely, low porosity cannot provide sufficient deformation space, leading to low sensitivity.

[0006] This invention is proposed to address the construction of porous fiber sensors. Summary of the Invention

[0007] To address the aforementioned technical problems, the present invention aims to provide a gradient-porous core-sheath structure sensing fiber based on gradient-induced phase separation and its preparation method. The obtained sensing fiber achieves highly sensitive and rapid detection of CO.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a gradient pore core-sheath structure sensing fiber based on gradient-induced phase separation, which is composed of a core layer, an intermediate layer and a sheath layer; The sheath layer forms a gradient pore structure along the radial direction of the sensing fiber, with the pore size gradually decreasing from the outer surface to the inside.

[0009] As a preferred embodiment of the present invention, the core layer is prepared from an MXene dispersion.

[0010] As a preferred embodiment of the present invention, the preparation of the MXene dispersion includes the following steps: 1~2g of lithium fluoride is added to 10~30mL of 10~12.5mol / L hydrochloric acid and stirred to dissolve. Then, Ti3AlC2 powder is gradually added and reacted. After the reaction is completed, the mixture is washed, freeze-dried, and finally dissolved in DMSO to obtain the final product.

[0011] As a preferred embodiment of the technical solution of the present invention, the intermediate layer is prepared from an ANF dispersion.

[0012] As a preferred embodiment of the present invention, the preparation of the ANF dispersion includes the following steps: mixing 50-100 mL of DMSO, 1-6 g of potassium hydroxide, and 10-30 mL of isopropanol at room temperature until homogeneous, and then adding 1-5 g of poly(p-phenylene terephthalamide) and stirring until homogeneous.

[0013] As a preferred embodiment of the present invention, the sheath is made of SnO2 / In2O3 heterojunction, ANF dispersion and silver nanowires.

[0014] As a preferred embodiment of the technical solution of the present invention, the preparation of the SnO2 / In2O3 heterojunction includes the following steps: dissolving SnO2 and In2O3 in deionized water at a mass ratio of 1:0.5~1, dispersing them evenly, and then drying them to obtain the SnO2 / In2O3 heterojunction. The preparation of the silver nanowires includes the following steps: dissolving 0.005~0.02g of sodium chloride and 0.1~1g of PVP in 40~100mL of ethylene glycol, stirring until homogeneous, then adding 0.2~1g of silver nitrate and continuing to stir; subsequently, transferring the resulting solution to a sterile container and heating it at 160~190℃ for 4~12h, cooling it to room temperature, and then centrifuging and drying it.

[0015] As a preferred embodiment of the present invention, the outer pore diameter of the sheath is greater than 10 μm, and the inner pore diameter is less than 3 μm.

[0016] Secondly, the present invention also provides a method for preparing the above-mentioned gradient pore core-sheath structure sensing fiber, comprising the following steps: Prepare an MXene dispersion with a concentration of 30~70mg / mL as the core spinning solution; Prepare an ANF dispersion as the intermediate layer spinning solution; SnO2 / In2O3 heterojunctions were dispersed in DMSO at a concentration of 4-6 mg / mL, followed by the addition of ANF dispersion at a concentration of 15-25 mg / mL; finally, silver nanowires were added at a concentration of 4-10 mg / mL, and the mixture was stirred evenly to serve as the sheath spinning solution. The core spinning solution, intermediate spinning solution, and sheath spinning solution are injected into the inner, middle, and outer channels of the spinneret, respectively. Wet spinning is used for extrusion, and the fibers are sequentially treated through two stages of coagulation baths. After treatment, the resulting nascent fibers are immersed in an aqueous solution of tert-butanol, the fibers are collected, and then freeze-dried.

[0017] In the above technical solution, based on wet spinning, and by controlling the proton exchange rate and phase separation kinetics between different coagulation baths, a gradient porous structure with gradually decreasing pore size from the outside to the inside is formed in the fiber sheath, which can significantly improve the gas transmission efficiency and response performance of the fiber sensor. Specifically: In the first coagulation bath, a mixed coagulation system containing organic solvents is used. Due to the low non-solvent strength of this coagulation bath, the solvent-non-solvent exchange process between the spinning solution and the coagulation bath is relatively slow, and the outer layer of the fiber first undergoes slow phase separation; at this time, the outer polymer chains have sufficient time for migration and rearrangement, forming a relatively loose aggregate structure locally, and gradually generating larger channels with better connectivity; this stage mainly controls the formation of large pores and the connectivity of channels in the outer layer of the fiber. Subsequently, the fiber enters the second coagulation bath, which is a proton-supplying solution that can rapidly diffuse into the fiber interior, causing the deprotonated aramid nanofibers to undergo rapid protonation and inducing the polymer chains to solidify rapidly. Due to the significantly increased internal phase separation rate, polymer chain migration is restricted, resulting in the formation of a smaller and more densely distributed microporous structure within the fiber.

[0018] Therefore, the combined effect of the slow phase separation in the outer layer induced by the first coagulation bath and the rapid phase separation in the inner layer induced by the second coagulation bath results in a gradient pore structure in the fiber sheath layer with pore size gradually decreasing from the outside to the inside in the radial direction. This structure provides a rapid gas transport channel in the outer layer and a higher specific surface area and more active adsorption sites in the inner layer, thus achieving both rapid mass transfer and efficient interfacial reactions. Clearly, the formation of the gradient pore structure in this invention originates from the difference in phase separation kinetics caused by the two coagulation baths.

[0019] As a preferred embodiment of the technical solution of the present invention, the extrusion speeds of the inner layer, the middle layer, and the outer layer channels are 10 μL / s, 20 μL / s, and 25 μL / s, respectively. The two-stage coagulation bath consists of: the first coagulation bath using a 50% (v / v) dimethyl sulfoxide aqueous solution containing 5% ammonium chloride; and the second coagulation bath using a 10% (v / v) acetic acid aqueous solution. In the aqueous solution of tert-butanol, the volume fraction of tert-butanol is 20%.

[0020] Thirdly, the present invention also provides the application of the above-mentioned sensing fibers in CO monitoring and early warning.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) Achieving controllable gradient porosity This invention utilizes a two-step coagulation bath to regulate phase separation kinetics, successfully constructing a gradient pore structure with larger outer pores and smaller inner pores in the fiber sheath.

[0022] (2) Significantly improve gas transport efficiency The gradient pore core-sheath structure sensing fiber prepared by this invention has large pores in the outer layer that facilitate the rapid diffusion of target gas into the fiber interior.

[0023] (3) Improve the utilization rate of active sites The gradient pore core-sheath structure sensing fiber prepared by this invention has a high specific surface area of ​​inner micropores, which can improve the adsorption and interfacial reaction efficiency of gas molecules.

[0024] (4) Improve gas sensing performance The gradient pore core-sheath structure sensing fiber prepared by this invention improves CO response performance by about 15% and shortens the response time to 19.28 s compared to the non-gradient porous structure. Attached Figure Description

[0025] Figure 1 Electron micrograph of the sensing fiber prepared in Example 5; Figure 2 The response results of the gradient pore sensing fiber in Example 5 are given at a CO concentration of 30 ppm. Figure 3 A comparison of the response values ​​and response times of gradient pore sensing fibers and non-gradient pore sensing fibers at a CO concentration of 30 ppm. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] Unless otherwise specified, all raw and auxiliary materials used in this invention are readily available.

[0028] Among them, Ti3AlC2 powder, 200 mesh, was purchased from Shanghai McLean Co., Ltd.; PVP, polyvinylpyrrolidone, with a molecular weight of 1,300,000, was purchased from Aladdin Co., Ltd.

[0029] Example 1 A method for preparing an MXene dispersion includes the following steps: 1.6 g of lithium fluoride was added to 20 mL of 12 mol / L hydrochloric acid and stirred for 30 min to dissolve. Then, 1 g of Ti3AlC2 powder was gradually added and the mixture was stirred at room temperature for 24 h to carry out the reaction. After the reaction was completed, the mixture was repeatedly washed by centrifugation with distilled water at 4000 rpm until the supernatant reached a neutral pH value. The collected sediment was then freeze-dried to obtain monolayer MXene nanosheets. Finally, the nanosheets were dissolved in DMSO to obtain an MXene dispersion.

[0030] Example 2 A method for preparing an ANF dispersion includes the following steps: Mix 80 mL DMSO, 1.5 g potassium hydroxide, and 20 mL isopropanol at room temperature until homogeneous. Then add 1.8 g poly(p-phenylene terephthalamide) (PPTA) and stir until homogeneous.

[0031] Example 3 A method for preparing a SnO2 / In2O3 heterojunction includes the following steps: SnO2 and In2O3 were dissolved in 100 mL of deionized water at a mass ratio of 1:0.8, ultrasonically dispersed for 2 h, and then dried at 60 °C to obtain SnO2 / In2O3 heterojunction.

[0032] Example 4 A method for preparing silver nanowires includes the following steps: Dissolve 0.01 g sodium chloride and 0.5 g PVP in 60 mL ethylene glycol and stir at 700 rpm for 15 min. Then add 0.51 g silver nitrate and continue stirring for 5 min. Transfer the resulting solution to a sterile container and heat at 180 °C for 8 h. After cooling to room temperature, centrifuge repeatedly at 3000 rpm and dry at 60 °C to obtain the final product.

[0033] Example 5 A method for preparing a gradient-porous core-sheath structure sensing fiber based on gradient-induced phase separation includes the following steps: Based on Example 1, an MXene dispersion with a concentration of 50 mg / mL was prepared as the core spinning solution; Based on Example 2, an ANF dispersion with a concentration of 18 mg / mL was prepared as the intermediate layer spinning solution; Based on Examples 3 and 4, SnO2 / In2O3 heterojunctions were dispersed in DMSO at a concentration of 5.4 mg / mL, followed by the addition of ANF dispersion (prepared in Example 2) at a concentration of 18 mg / mL; finally, silver nanowires were added at a concentration of 5 mg / mL, and the mixture was stirred evenly to serve as the sheath spinning solution. Coaxial wet spinning was performed using a three-coaxial spinneret, with the core layer spinneret inner diameter being 0.84 mm, the intermediate layer spinneret inner diameter being 1.80 mm, and the sheath layer spinneret inner diameter being 2.70 mm. The core layer spinning solution, intermediate layer spinning solution, and sheath layer spinning solution were injected into the inner, intermediate, and outer layer channels of the spinneret, respectively. Wet spinning was performed, with extrusion speeds of 10 μL / s, 20 μL / s, and 25 μL / s for the inner, intermediate, and outer layer channels, respectively. The fibers were then sequentially treated through a two-stage coagulation bath. After treatment, the resulting nascent fibers were immersed in a 20% (v / v) tert-butanol aqueous solution, collected, and freeze-dried for 5 hours.

[0034] The two-stage coagulation bath process is as follows: The first coagulation bath uses a 50% (v / v) dimethyl sulfoxide aqueous solution containing 5% ammonium chloride, with a residence time of 30 seconds. Due to the slow solvent exchange rate, slow phase separation occurs on the outer side of the sheath, forming a larger porous structure. NH 4+ The second coagulation bath uses a 10% volume fraction aqueous acetic acid solution with a residence time of 120s. The proton exchange rate is significantly increased in the second coagulation bath, and ANF is rapidly protonated and solidified to form a dense microporous structure. This results in a gradient pore structure that gradually decreases from the outside to the inside in the fiber sheath.

[0035] Example 6 A method for preparing a gradient-porous core-sheath structure sensing fiber based on gradient-induced phase separation includes the following steps: Based on Example 1, an MXene dispersion with a concentration of 50 mg / mL was prepared as the core spinning solution; Based on Example 2, an ANF dispersion with a concentration of 18 mg / mL was prepared as the intermediate layer spinning solution; Based on Examples 3 and 4, SnO2 / In2O3 heterojunctions were dispersed in DMSO at a concentration of 5.4 mg / mL, followed by the addition of ANF dispersion (prepared in Example 2) at a concentration of 18 mg / mL; finally, silver nanowires were added at a concentration of 5 mg / mL, and the mixture was stirred evenly to serve as the sheath spinning solution. Coaxial wet spinning was performed using a three-coaxial spinneret, with the core layer spinneret inner diameter being 0.84 mm, the intermediate layer spinneret inner diameter being 1.80 mm, and the sheath layer spinneret inner diameter being 2.70 mm. The core layer spinning solution, intermediate layer spinning solution, and sheath layer spinning solution were injected into the inner, intermediate, and outer layer channels of the spinneret, respectively. Wet spinning was performed, with extrusion speeds of 10 μL / s, 20 μL / s, and 25 μL / s for the inner, intermediate, and outer layer channels, respectively. The fibers were then sequentially treated through a two-stage coagulation bath. After treatment, the resulting nascent fibers were immersed in a 20% (v / v) tert-butanol aqueous solution, collected, and freeze-dried for 5 hours.

[0036] The two-stage coagulation bath process is as follows: the first coagulation bath uses a 50% volume fraction dimethyl sulfoxide aqueous solution containing 5% ammonium chloride, with a residence time of 10s; the second coagulation bath uses a 10% volume fraction acetic acid aqueous solution, with a residence time of 100s.

[0037] Example 7 A method for preparing a gradient-porous core-sheath structure sensing fiber based on gradient-induced phase separation includes the following steps: Based on Example 1, an MXene dispersion with a concentration of 50 mg / mL was prepared as the core spinning solution; Based on Example 2, an ANF dispersion with a concentration of 18 mg / mL was prepared as the intermediate layer spinning solution; Based on Examples 3 and 4, SnO2 / In2O3 heterojunctions were dispersed in DMSO at a concentration of 5.4 mg / mL, followed by the addition of ANF dispersion (prepared in Example 2) at a concentration of 18 mg / mL; finally, silver nanowires were added at a concentration of 5 mg / mL, and the mixture was stirred evenly to serve as the sheath spinning solution. Coaxial wet spinning was performed using a three-coaxial spinneret, with the core layer spinneret inner diameter being 0.84 mm, the intermediate layer spinneret inner diameter being 1.80 mm, and the sheath layer spinneret inner diameter being 2.70 mm. The core layer spinning solution, intermediate layer spinning solution, and sheath layer spinning solution were injected into the inner, intermediate, and outer layer channels of the spinneret, respectively. Wet spinning was performed, with extrusion speeds of 10 μL / s, 20 μL / s, and 25 μL / s for the inner, intermediate, and outer layer channels, respectively. The fibers were then sequentially treated through a two-stage coagulation bath. After treatment, the resulting nascent fibers were immersed in a 20% (v / v) tert-butanol aqueous solution, collected, and freeze-dried for 5 hours.

[0038] The two-stage coagulation bath process is as follows: the first coagulation bath uses a 50% volume fraction dimethyl sulfoxide aqueous solution containing 5% ammonium chloride, with a residence time of 60s; the second coagulation bath uses a 10% volume fraction acetic acid aqueous solution, with a residence time of 110s.

[0039] Comparative Example 1 Wet spinning was performed using a traditional single coagulation bath of pure water, with a residence time of 150 seconds, and all other steps were the same as in Example 5.

[0040] The performance of the sensing fibers prepared in Example 5 and Comparative Example 1 was tested. The test methods and results are as follows: Figure 1 The image shows an electron microscope image of the sensing fiber in Example 5 (the right side is the outer layer and the left side is the inner layer). As can be seen from the image, the fiber has a gradient porosity structure.

[0041] CO gas sensing experiments were conducted on gradient porosity sensing fibers. Specifically, the gradient porosity sensing fiber was placed in a sealed gas chamber, with wires connected to both ends of the fiber and then to a multimeter to monitor real-time changes in fiber resistance. A certain concentration of CO gas was then introduced, and the resistance changes of the sensing fiber were observed and recorded in real time. The response value of the sensing fiber was defined as ΔR / R0 × 100%, where R0 represents the baseline resistance of the sensor in air or its initial state, and ΔR is the resistance change of the sensing fiber after exposure to the target gas stimulus, i.e., the baseline resistance of the sensing fiber in air or its initial state minus the real-time resistance of the sensing fiber after contact with the target gas stimulus. See [link to relevant documentation]. Figure 2 Experiments confirmed that the SnO2 / In2O3 composite gas-sensitive material forms a stable heterojunction structure within the fiber. When the gradient porosity sensing fiber is exposed to a CO gas environment, CO molecules undergo a redox reaction with adsorbed oxygen on the material surface, releasing electrons that flow back to the conductive channels. This causes a change in the interfacial carrier concentration, resulting in a significant change in the overall fiber resistance. Experimental results show that the gradient porosity sensing fiber can respond to 30 ppm CO gas in approximately 23 seconds, with a resistance response value as high as 50%.

[0042] Further, see Figure 3The gradient pore structure significantly shortened the response time of the sensing fiber to CO gas, compared to approximately 41 s for the non-gradient pore structure. This gradient pore structure significantly promoted gas diffusion and transport, effectively improving the sensing response rate. This is primarily due to the multi-level gas diffusion channels formed within the fiber by the gradient pore structure constructed in this study. On one hand, larger pores facilitate the rapid entry of external CO gas into the fiber, shortening the gas transport path; on the other hand, smaller pores increase the contact probability between the gas and the gas-sensitive material, thereby improving the effective utilization efficiency of the active sites. This gradient pore structure not only significantly accelerated the gas adsorption and desorption process and shortened the response time of the sensing fiber to CO gas, but also improved the utilization rate of the gas-sensitive material within the fiber and the overall sensing performance. In summary, the construction of the gradient pore structure played a crucial role in promoting the sensing fiber's response to CO gas, effectively accelerating the gas diffusion and transport process and significantly improving the sensing response rate and overall gas-sensitive performance.

[0043] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of individual raw materials in the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A gradient-porous core-sheath structure sensing fiber based on gradient-induced phase separation, characterized in that, It consists of a core layer, an intermediate layer, and a sheath layer; The sheath layer forms a gradient pore structure along the radial direction of the sensing fiber, with the pore size gradually decreasing from the outer surface to the inside.

2. The sensing fiber with a gradient porosity core-sheath structure based on gradient-induced phase separation according to claim 1, characterized in that, The core layer was prepared from an MXene dispersion.

3. The sensing fiber with a gradient porosity core-sheath structure based on gradient-induced phase separation according to claim 2, characterized in that, The preparation of the MXene dispersion includes the following steps: 1~2g of lithium fluoride is added to 10~30mL of 10~12.5mol / L hydrochloric acid and stirred to dissolve. Then, Ti3AlC2 powder is gradually added and reacted. After the reaction is completed, the mixture is washed, lyophilized, and finally dissolved in DMSO to obtain the final product.

4. The sensing fiber with a gradient-induced phase separation-based gradient porosity core-sheath structure according to claim 1, characterized in that, The intermediate layer is prepared from an ANF dispersion.

5. A gradient-induced phase separation-based gradient porosity core-sheath structure sensing fiber according to claim 4, characterized in that, The preparation of the ANF dispersion includes the following steps: 50-100 mL DMSO, 1-6 g potassium hydroxide, and 10-30 mL isopropanol are mixed evenly at room temperature, and then 1-5 g poly(p-phenylene terephthalamide) is added and stirred evenly.

6. The sensing fiber with a gradient porosity core-sheath structure based on gradient-induced phase separation according to claim 1, characterized in that, The sheath is made of SnO2 / In2O3 heterojunction, ANF dispersion and silver nanowires.

7. A sensing fiber with a gradient-induced phase separation-based gradient porosity core-sheath structure according to claim 6, characterized in that, The preparation of the SnO2 / In2O3 heterojunction includes the following steps: SnO2 and In2O3 are dissolved in deionized water at a mass ratio of 1:0.5~1, dispersed evenly, and then dried to obtain the SnO2 / In2O3 heterojunction; The preparation of the silver nanowires includes the following steps: dissolving 0.005~0.02g of sodium chloride and 0.1~1g of PVP in 40~100mL of ethylene glycol, stirring until homogeneous, then adding 0.2~1g of silver nitrate and continuing to stir; subsequently, transferring the resulting solution to a sterile container and heating it at 160~190℃ for 4~12h, cooling it to room temperature, and then centrifuging and drying it.

8. The sensing fiber with a gradient porosity core-sheath structure based on gradient-induced phase separation according to claim 1, characterized in that, The outer pore size of the sheath is greater than 10 μm; the inner pore size is less than 3 μm.

9. A method for preparing the gradient pore core-sheath structure sensing fiber according to any one of claims 1 to 8, characterized in that, The steps include the following: Prepare an MXene dispersion with a concentration of 30~70mg / mL as the core spinning solution; Prepare an ANF dispersion as the intermediate layer spinning solution; SnO2 / In2O3 heterojunctions were dispersed in DMSO at a concentration of 4-6 mg / mL, followed by the addition of ANF dispersion at a concentration of 15-25 mg / mL; finally, silver nanowires were added at a concentration of 4-10 mg / mL, and the mixture was stirred evenly to serve as the sheath spinning solution. The core spinning solution, intermediate spinning solution, and sheath spinning solution are injected into the inner, middle, and outer channels of the spinneret, respectively. Wet spinning is used for extrusion, and the fibers are sequentially treated through two stages of coagulation baths. After treatment, the resulting nascent fibers are immersed in an aqueous solution of tert-butanol, the fibers are collected, and then freeze-dried.

10. The preparation method according to claim 9, characterized in that, The extrusion rates of the inner, middle, and outer channels are 10 μL / s, 20 μL / s, and 25 μL / s, respectively. The two-stage coagulation bath consists of: the first coagulation bath using a 50% (v / v) dimethyl sulfoxide aqueous solution containing 5% ammonium chloride; and the second coagulation bath using a 10% (v / v) acetic acid aqueous solution. In the aqueous solution of tert-butanol, the volume fraction of tert-butanol is 20%.

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