Composite nanofiber film and method of making

Abstract

This invention relates to a composite nanofiber film and its preparation method. The method involves electrospinning a SiOC precursor and a readily spinnable polymer, dispersing and dissolving them in an organic solvent. The composite is then added to the spinning solution to obtain a precursor composite nanofiber film. The precursor nanofiber film is further subjected to a non-melting treatment and high-temperature pyrolysis to ultimately obtain a TiO2 / Co / SiOC composite nanofiber film with titanium dioxide (TiO2) and cobalt (Co) nanocrystals dispersed within the silicon-oxygen-carbon (SiOC) nanofibers. This invention is the first to utilize electrospinning to modify SiOC nanofibers and achieve controllable preparation of TiO2 / Co / SiOC composite nanofiber films. The morphology, structure, and distribution of the nanofibers are controlled by adjusting the concentration of the precursor solution, spinning voltage, fiber output rate, and collection method. The dielectric properties are altered by changing the composite amount of the titanium and cobalt phases. The elemental composition and phase structure of the nanofibers are controlled by varying the pyrolysis temperature and holding time. The resulting product exhibits excellent compressive elasticity and thermal insulation properties, making it highly valuable for practical applications.

Description

Technical Field

[0001] This invention belongs to the field of composite fiber material preparation, and relates to a flexible and heat-insulating titanium dioxide / cobalt / silicon-oxygen-carbon (TiO2 / Co / SiOC) composite nanofiber film with electromagnetic wave absorption properties and its preparation method. The entire preparation process includes the preparation of the composite precursor solution, electrospinning of the composite precursor solution, and curing and heat treatment of the composite precursor nanofiber film. The final composite fiber film exhibits excellent flexibility, heat insulation properties, and electromagnetic wave absorption properties. Background Technology

[0002] To protect communication facilities and human health from the harmful effects of microwave radiation and to meet the demands of emerging electronic products, it is essential to develop multifunctional materials that can withstand high temperatures and adapt to complex and harsh environments while ensuring high electromagnetic wave absorption performance. Therefore, exploring materials with excellent thermal insulation properties, outstanding flexibility and toughness, good processability, and ultra-light weight is the development trend of multifunctional microwave absorbing materials.

[0003] Polymer-derived ceramics (PDCs) based on silicon are important phases, suitable not only for structural materials but also for functional applications. They exhibit good creep and oxidation resistance in extreme environments, low density, and readily available and inexpensive raw materials. However, SiOC ceramics derived from pure precursor polymers suffer from poor microwave absorption (MA) performance due to their low dielectric properties. Using SiOC fibers as a matrix and combining them with dielectric or magnetic materials can fully leverage the advantages of different components and further improve electromagnetic wave absorption performance. Therefore, it is necessary to study new preparation methods to improve the dielectric properties of SiOC ceramics to enhance their electromagnetic wave absorption performance. The MA performance of PDCs-SiOC ceramics can also be improved through metal doping. Utilizing this principle, Qian et al. (Journal of Alloys and Compounds 843 (2020)) successfully prepared Fe-containing SiOC ceramic composites using the PDC process. The Fe source promotes the formation of SiC particles, enhances the interfacial polarization of SiOC ceramics, thereby improving its dielectric properties; it can also improve the dielectric properties by introducing a high-dielectric-loss phase. For example, Duan et al. (Journal of the European Ceramic Society 34(2)(2014) 257-266) prepared SiC-modified n-SiC / SiOC ceramics by thermal decomposition, which enhanced the electronic dipole polarization and interface scattering of the ceramics and ultimately enhanced their absorption properties.

[0004] However, the inherent brittleness of ceramics severely hinders their application in complex environments. Researchers have reportedly employed strategies such as microcrack toughening, phase transformation toughening, and whisker toughening to prepare flexible ceramic films or thin films that can withstand bending to a certain extent. However, these films or sheets of ceramic struggle to release external stress during significant bending deformation, resulting in limited improvement in flexibility. Therefore, one-dimensional and nano-sized ceramic materials are key to improving material flexibility and ductility, as well as reducing material density. This allows ceramic materials to more effectively adapt to complex shapes and surfaces, increasing the material's coverage area and thus improving electromagnetic wave absorption performance. Compared to ceramic films or sheets, one-dimensional ceramic fibers possess a high aspect ratio and good continuity, facilitating the formation of conductive networks, enhancing overall conductivity, and improving electromagnetic wave absorption efficiency. Chinese patents CN 108866810 A and CN116926785A disclose SiC nanofibers, SiC@SiO2 / carbon (Journal of Materials Chemistry C7(48)(2019)15233-15242) and PVC / SiO2 / SiO2@Ag (Journal of Membrane Science 661(2022)), as well as SiOC nanowires disclosed in CN 116288759 A and CN 112723356A, demonstrating the feasibility of one-dimensional and nanoscale ceramic materials. However, breakthroughs are urgently needed in improving the electromagnetic wave absorption performance and optimizing the mechanical properties (flexibility, compressive strength, and thermal insulation performance) of SiOC nanofibers.

[0005] Among the above preparation methods, electrospinning, as a novel processing method for preparing ultrafine nanofibers, is simple to operate, operates under mild conditions, and has low cost. It also boasts a fast preparation speed and high production efficiency, enabling rapid large-scale production of SiOC nanofibers. Nanofibers prepared by electrospinning typically exhibit high purity and uniformity, which is beneficial for improving the material's performance and stability. SiOC nanofibers prepared based on electrospinning technology have a large specific surface area and aspect ratio, and many desirable properties can be designed and achieved by adjusting the spinning process and modifying the spinning system. Meanwhile, Co exhibits significant magnetic loss at high frequencies, which can contribute to the attenuation efficiency of attenuators. On the other hand, among numerous dielectric materials, TiO2, as an widely studied n-type semiconductor material, possesses excellent dielectric loss properties. Furthermore, the abundant resources, inexpensive raw materials, and non-toxic environment of TiO2 have attracted considerable interest. CN114736034A discloses a method for preparing gradient porous Ti3AlC2 / SiC composite materials using template impregnation-pyrolysis sintering. These composites exhibit high porosity, complete and uniform pore structure, good impedance matching with free space, and excellent electromagnetic absorption properties. Although the product has a low density, this method is cumbersome and time-consuming. CN 111574958A discloses a method for preparing Ti3C2T... x A core-edge structured carbide MXene / SiO2 nanoplatelet ultrathin microwave absorbing material composed of SiO2 and a core-edge structure exhibits high absorption intensity and a large effective absorption bandwidth, demonstrating excellent absorption performance in the X and Ku bands. CN 110093686 B discloses a TiO2 / Co-supported carbon fiber nanomaterial for electromagnetic wave absorption, which also exhibits excellent absorption performance. However, the overall performance of the products disclosed above, including flexibility, compression resilience, thermal insulation, and electromagnetic wave absorption, needs further improvement. Summary of the Invention

[0006] The purpose of this invention is to provide a flexible and thermally insulating titanium dioxide / cobalt / silicon-oxygen-carbon (TiO2 / Co / SiOC) composite nanofiber film with electromagnetic wave absorption properties, addressing the shortcomings of existing technologies. Another objective is to provide a method for preparing the aforementioned composite nanofiber film. This invention addresses the advantages and disadvantages of one-dimensional SiOC materials in electromagnetic wave absorption at high temperatures, as well as the limitations of their fabrication processes. By forming an organic nanoscale composite with TiO2 and elemental Co phases and one-dimensional SiOC materials, and utilizing electrospinning, a continuous flexible TiO2 / Co / SiOC nanocomposite fiber film was prepared. This nanofiber film exhibits excellent electromagnetic wave absorption and thermal insulation properties. Modified SiOC nanofibers were prepared using electrospinning, a simple and low-cost process, resulting in a TiO2 / Co / SiOC composite nanofiber film with excellent mechanical properties, tunable electrical conductivity, and outstanding flexibility. The product also possesses excellent characteristics such as low density, good compression recovery, good thermal insulation, and excellent electromagnetic wave absorption, enabling the composite material to better adapt to harsh working environments.

[0007] The technical solution of the present invention is as follows: a composite nanofiber film, characterized in that: titanium dioxide (TiO2) and cobalt (Co) nanocrystals are uniformly dispersed in silicon-oxygen-carbon (SiOC) nanofibers, wherein the size of titanium dioxide (TiO2) nanocrystals is 5-10 nm, and the size of cobalt (Co) nanocrystals is 5-10 nm; the mass percentages of TiO2 and Co nanocrystals in the composite nanofiber film are 7-11% and 1-4%, respectively.

[0008] The present invention also provides a method for preparing the above-mentioned composite nanofiber film, the specific steps of which are as follows: Step 1: Disperse and dissolve the SiOC precursor and the easily spinnable polymer in an organic solvent to form a solution; wherein the mass ratio of the SiOC precursor to the polymer is (0.5~4.5):1;

[0009] Step 2: The cobalt-containing compound and the titanium-containing compound are then uniformly dispersed in the solution of Step 1 to obtain a uniformly dispersed precursor spinning solution; wherein the mass of the cobalt-containing compound and the titanium-containing compound added are 5% to 50% and 10% to 60% of the mass of the SiOC precursor, respectively.

[0010] Step 3: Place the precursor spinning solution into a syringe, attach a stainless steel needle to the tip of the syringe, and then load it into an electrospinning device for spinning; wherein the positive voltage of spinning is 15-20kV, the negative voltage is 15-20kV, the feed flow rate is 0.1-0.3mL / min, the distance between the needle and the collector is 10-15cm, and the environment is room temperature.

[0011] Step 4: The precursor nanofiber film collected on the collector is subjected to non-melting treatment at a temperature of 160–210°C.

[0012] Step 5: Place the non-melting precursor fiber film in a carbon crucible, and then perform high-temperature heat treatment under a protective atmosphere. The heat treatment temperature is 700-1200℃, and the holding time is 3-5h to prepare TiO2 / Co / SiOC composite nanofiber film. The heating rate during the high-temperature heat treatment is 5-10℃ / min.

[0013] Preferably, the SiOC precursor is polymethylsilsesquioxane (MK) or polysiloxane (PSO). Preferably, the easily spinnable polymer is polystyrene (PS), polycaprolactone (PCL), or polyvinylpyrrolidone (PVP).

[0014] Preferably, the organic solvent is a mixture of one of toluene, chloroform, or isopropanol with N,N-dimethylformamide, or a mixture of one of tetrahydrofuran or chloroform with xylene; wherein the volume ratio of one of toluene, chloroform, or isopropanol to N,N-dimethylformamide in the mixed solvent is (1-5):1; the volume ratio of one of tetrahydrofuran or chloroform to xylene is 1:(2-3); and the concentration of the SiOC precursor in the solution of step 1 is 0.075-0.225 g / ml.

[0015] Preferably, the cobalt-containing compound is cobalt nitrate Co(NO3)2 or cobalt acetylacetonate Co(acac)3.

[0016] Preferably, the titanium-containing compound is nano-titanium dioxide (TiO2) or titanium oxyacetylacetonate (TiO(acac)2).

[0017] Preferably, the collector is a roller collector. Preferably, the inner diameter of the stainless steel needle is 0.51–1.69 mm.

[0018] Beneficial effects:

[0019] This invention proposes a flexible titanium dioxide / cobalt / silicon-oxygen-carbon (TiO2 / Co / SiOC) composite nanofiber film with electromagnetic wave absorption and thermal insulation properties, and its preparation method. With the introduction of titanium and cobalt phases, the resulting titanium dioxide (TiO2) and cobalt nanocrystals are dispersed within the silicon-oxygen-carbon (SiOC) nanofibers. On one hand, this improves the spinning performance of the SiOC precursor, resulting in TiO2 / Co / SiOC composite nanofibers that significantly enhance fiber diameter, flexibility, and thermal insulation performance compared to pure SiOC fibers. On the other hand, the introduction of TiO2 and Co phases significantly improves the electrical conductivity and dielectric properties of the SiOC nanofibers, thereby enhancing the electromagnetic wave absorption performance of the TiO2 / Co / SiOC composite nanofiber film.

[0020] This invention marks the first time that a simple and low-cost process has been used to controllably prepare TiO2 / Co / SiOC composite nanofiber films with excellent comprehensive mechanical properties, thermal insulation properties, and superior electromagnetic wave absorption properties. The morphology, structure, and distribution of the nanofibers are controlled by adjusting the concentration of different components in the precursor solution, spinning voltage, feed rate, and needle-to-collector distance. The dielectric properties are altered by changing the composite amount of the titanium and cobalt phases. The elemental composition and phase structure of the nanofibers are controlled by varying the heat treatment temperature, holding temperature, and time. Attached Figure Description

[0021] Figure 1 A schematic diagram of the preparation process of the TiO2 / Co / SiOC composite nanofiber film in Example 1;

[0022] Figure 2 SEM images of the TiO2 / Co / SiOC composite nanofiber film in Example 1: (a) after non-melting treatment; (b) after high-temperature heat treatment.

[0023] Figure 3 The illustrations in Example 1 show the flexibility of the TiO2 / Co / SiOC composite nanofiber film, including (a) bending, (b) twisting, (c) folding, and (d) cutting.

[0024] Figure 4 The microwave absorption performance of the TiO2 / Co / SiOC composite nanofiber film in Example 1 is illustrated.

[0025] Figure 5 To illustrate the implementation of Example 1, the stress-strain curves of the TiO2 / Co / SiOC composite nanofiber film are shown as follows: (a) stress-strain curves under different compressive strains; (b) stress-strain curves after different number of cycles; and (c) stress retention and maximum stress after different compressive strain tests.

[0026] Figure 6 The diagram illustrates the thermal insulation performance of the TiO2 / Co / SiOC composite nanofiber film in Example 1. Detailed Implementation

[0027] The present invention will now be further described in conjunction with the embodiments and accompanying drawings:

[0028] Example 1:

[0029] According to the flowchart Figure 1 As shown, the specific preparation method is as follows:

[0030] (1) Dissolve 1.8g of polymethylsilsesquioxane MK and 0.9g of polyvinylpyrrolidone PVP in a 12mL mixed solution of isopropanol and N,N-dimethylformamide DMF in a volume ratio of 5:1 and stir magnetically for 2h until completely dissolved to form a homogeneous MK / PVP spinning solution.

[0031] (2) Weigh 5% of MK cobalt acetylacetone Co(acac)3 and 10% of MK titanium oxyacetylacetone TiO(acac)2 and add them to the solution in step (1). After magnetic stirring for 3 hours, a mixed spinning solution of MK / PVP / Ti / Co is obtained.

[0032] (3) Draw 10 mL of the solution from step (2) using a syringe. Select a needle with an inner diameter of 0.51 mm, a feed rate of 0.3 mL / min, a positive spinning voltage of 20 kV, a negative spinning voltage of 15 kV, a nozzle-collector distance of 15 cm, a roller collector, and a roller rotation speed of 500 r / min. Obtain the composite fiber membrane.

[0033] (4) The precursor composite fiber in step (3) is subjected to non-melting treatment at a temperature of 210°C.

[0034] (5) The composite fibers after the non-melting treatment in step (4) are subjected to high-temperature pyrolysis treatment. The pyrolysis temperature is 700℃, the holding time is 3h, the heating rate is 5℃ / min, and the entire pyrolysis process is protected by argon gas. The titanium dioxide (TiO2) and cobalt (Co) nanocrystals in the composite nanofiber film are uniformly dispersed in the silicon-oxygen-carbon (SiOC) nanofibers. The size of the titanium dioxide (TiO2) nanocrystals is 10nm, and the size of the cobalt (Co) nanocrystals is 10nm. The mass percentages of TiO2 and Co nanocrystals in the TiO2 / Co / SiOC composite nanofiber film are 7wt% and 4wt%, respectively.

[0035] Figure 2 The images show SEM images of the fiber film after (a) non-melting treatment and (b) high-temperature heat treatment. It can be seen that the fiber diameter is significantly reduced after heat treatment, and a continuous three-dimensional network structure is formed. Figure 3It can be seen that (a) bending; (b) twisting; (c) folding; (d) cutting represent the flexibility of the fiber. Figure 4 The nanofiber thin film demonstrates excellent electromagnetic wave absorption performance, with a maximum bandwidth of 8.64 GHz at 3.25 mm and a minimum reflection loss of -66.00 dB. Figure 5 (a) Stress-strain curves of nanofiber films under different compressive strains; (b) Stress-strain curves after different number of cycles; (c) Stress retention and maximum stress after different compressive strain tests. It can be seen that after different compressive strain tests, the film material can recover to its original position, and after 500 cycles of loading and unloading, it still maintains more than 92% of the compressive stress. Figure 6 The demonstration of the heat insulation performance of the nanofiber film shows that the fiber film allowed a fresh flower to remain undamaged for 5 minutes on a metal plate exposed to the intense flame of a butane torch; in contrast, a flower placed directly on the metal plate was burned up in just 90 seconds.

[0036] Example 2:

[0037] (1) Dissolve 2.7g of polymethylsilsesquioxane MK and 1.8g of polystyrene PS in a 12mL mixed solution of toluene and N,N-dimethylformamide DMF in a volume ratio of 1:1 and stir magnetically for 2h until completely dissolved to form a homogeneous MK / PVP spinning solution.

[0038] (2) Weigh 5% of cobalt nitrate Co(NO3)2 and 60% of titanium oxyacetate TiO(acac)2 by weight of MK and add them to the solution in step (1). After magnetic stirring for 3 hours, a mixed spinning solution of MK / PVP / Ti / Co is obtained.

[0039] (3) Draw 10 mL of the solution from step (2) using a syringe. Select a needle with an inner diameter of 1.69 mm, a feed rate of 0.1 mL / min, a positive spinning voltage of 20 kV, a negative spinning voltage of 15 kV, a nozzle-collector distance of 10 cm, a roller collector, and a roller rotation speed of 500 r / min. Obtain the composite fiber membrane.

[0040] (4) The precursor composite fiber in step (3) is subjected to non-melting treatment at a temperature of 190°C.

[0041] (5) The composite fibers after the non-melting treatment in step (4) are subjected to high-temperature pyrolysis treatment. The pyrolysis temperature is 1000℃, the holding time is 5h, the heating rate is 10℃ / min, and the entire pyrolysis process is protected by argon gas. The titanium dioxide (TiO2) and cobalt (Co) nanocrystals in the composite nanofiber film are uniformly dispersed in the silicon-oxygen-carbon (SiOC) nanofibers. The size of the titanium dioxide (TiO2) nanocrystals is 5nm, and the size of the cobalt (Co) nanocrystals is 10nm. The mass percentages of TiO2 and Co nanocrystals in the TiO2 / Co / SiOC composite nanofiber film are 11% and 3wt%, respectively.

[0042] Example 3:

[0043] (1) Dissolve 0.9g of polysiloxane PSO and 1.8g of polycaprolactone PCL in 12mL of a mixed solution of xylene and chloroform in a volume ratio of 3:1 and stir magnetically for 2h until completely dissolved to form a homogeneous MK / PVP spinning solution.

[0044] (2) Weigh 50% of cobalt acetylacetone Co(acac)3 and 10% of nano titanium dioxide TiO2 by weight of PSO and add them to the solution in step (1). After magnetic stirring for 3 hours, a mixed spinning solution of MK / PVP / Ti / Co is obtained.

[0045] (3) Draw 10 mL of the solution from step (2) using a syringe. Select a needle with an inner diameter of 0.9 mm, a feed rate of 0.1 mL / min, a positive spinning voltage of 20 kV, a negative spinning voltage of 15 kV, a distance of 10 cm between the nozzle and the collector, and a roller collector with a rotation speed of 500 r / min. Obtain the composite fiber membrane.

[0046] (4) The precursor composite fiber in step (3) is subjected to non-melting treatment at a temperature of 210°C.

[0047] (5) The composite fibers after the non-melting treatment in step (4) are subjected to high-temperature pyrolysis treatment. The pyrolysis temperature is 700℃, the holding time is 3h, the heating rate is 10℃ / min, and the entire pyrolysis process is protected by argon gas. The titanium dioxide (TiO2) and cobalt (Co) nanocrystals in the composite nanofiber film are uniformly dispersed in the silicon-oxygen-carbon (SiOC) nanofibers. The size of the titanium dioxide (TiO2) nanocrystals is 5nm, and the size of the cobalt (Co) nanocrystals is 5nm. The mass percentages of TiO2 and Co nanocrystals in the TiO2 / Co / SiOC composite nanofiber film are 7wt% and 1wt%, respectively.

[0048] Example 4:

[0049] (1) Dissolve 2.7g of polysiloxane PSO and 0.6g of polyvinylpyrrolidone PVP in a 12mL mixed solution of chloroform and N,N-dimethylformamide in a volume ratio of 1:1 and stir magnetically for 2h until completely dissolved to form a homogeneous MK / PVP spinning solution.

[0050] (2) Weigh 50% of cobalt nitrate Co(NO3)2 and 60% of nano titanium dioxide TiO2 by weight of PSO and add them to the solution in step (1). After magnetic stirring for 3 hours, MK / PVP / Ti / Co mixed spinning solution is obtained.

[0051] (3) Draw 10 mL of the solution from step (2) using a syringe. Select a needle with an inner diameter of 0.51 mm, a feed rate of 0.3 mL / min, a positive spinning voltage of 15 kV, a negative spinning voltage of 15 kV, a distance of 15 cm between the nozzle and the collector, and a roller collector with a rotation speed of 500 r / min. Obtain the composite fiber membrane.

[0052] (4) The precursor composite fiber in step (3) is subjected to non-melting treatment at a temperature of 180°C.

[0053] (5) The composite fibers after the non-melting treatment in step (4) are subjected to high-temperature pyrolysis treatment. The pyrolysis temperature is 1200℃, the holding time is 3h, the heating rate is 5℃ / min, and the entire pyrolysis process is protected by argon gas. The titanium dioxide (TiO2) and cobalt (Co) nanocrystals in the composite nanofiber film are uniformly dispersed in the silicon-oxygen-carbon (SiOC) nanofibers. The size of the titanium dioxide (TiO2) nanocrystals is 10nm, and the size of the cobalt (Co) nanocrystals is 5nm. The mass percentages of TiO2 and Co nanocrystals in the TiO2 / Co / SiOC composite nanofiber film are 11wt% and 1wt%, respectively.

[0054] Example 5:

[0055] (1) Dissolve 0.9g of polymethylsilsesquioxane MK and 0.6g of polyvinylpyrrolidone PVP in 12mL of a mixed solution of xylene and tetrahydrofuran in a volume ratio of 2:1 and stir magnetically for 2h until completely dissolved to form a homogeneous MK / PVP spinning solution.

[0056] (2) Weigh 5% of cobalt nitrate Co(NO3)2 and 10% of nano titanium dioxide TiO2 by weight of MK and add them to the solution in step (1). After magnetic stirring for 3 hours, a mixed spinning solution of MK / PVP / Ti / Co is obtained.

[0057] (3) Use a syringe to draw 10 mL of the solution from step (2), select a needle with an inner diameter of 1.69 mm, a push speed of 0.1 mL / min, a spinning positive voltage of 20 kV, a negative voltage of 20 kV, a distance of 10 cm between the nozzle and the collector, a collector type of roller collector, and a roller speed of 500 r / min to obtain a composite fiber membrane.

[0058] (4) The precursor composite fiber in step (3) is subjected to non-melting treatment at a temperature of 160°C.

[0059] (5) The composite fibers after the non-melting treatment in step (4) are subjected to high-temperature pyrolysis treatment. The pyrolysis temperature is 900℃, the holding time is 5h, the heating rate is 10℃ / min, and the entire pyrolysis process is protected by argon gas. The titanium dioxide (TiO2) and cobalt (Co) nanocrystals in the composite nanofiber film are uniformly dispersed in the silicon-oxygen-carbon (SiOC) nanofibers. The size of the titanium dioxide (TiO2) nanocrystals is 5nm, and the size of the cobalt (Co) nanocrystals is 10nm. The mass percentages of TiO2 and Co nanocrystals in the TiO2 / Co / SiOC composite nanofiber film are 7wt% and 4wt%, respectively.

[0060] Table 1 compares the performance of TiO2 / Co / SiOC composite nanofiber films in Examples 1-5 with those in other published literature.

[0061]

Claims

1. A composite nanofiber film, characterized by: Titanium dioxide (TiO2) and cobalt (Co) nanocrystals are uniformly dispersed in silicon-oxygen-carbon (SiOC) nanofibers, wherein the size of the TiO2 nanocrystals is 5–10 nm, and the size of the Co nanocrystals is 5–10 nm; the mass percentages of TiO2 and Co nanocrystals in the composite nanofiber film are 7–11% and 1–4%, respectively; the film is prepared by the following method, the specific steps of which are as follows: Step 1: Disperse and dissolve the SiOC precursor polymethylsilsesquioxane MK and the easily spinnable polymer polyvinylpyrrolidone PVP in an organic solvent to form a solution; wherein the mass ratio of SiOC precursor to polymer is (0.5~4.5):1; Step 2: Then, the cobalt-containing compound acetylacetone cobalt (Co(acac)3) and the titanium-containing compound acetylacetone titanium oxy (TiO(acac)2) are uniformly dispersed in the solution of step 1 to obtain a uniformly dispersed precursor spinning solution; The mass percentages of cobalt-containing compounds and titanium-containing compounds added are 5%–50% and 10%–60% of the mass of the SiOC precursor, respectively. Step 3: Place the precursor spinning solution into a syringe, attach a stainless steel needle to the front end of the syringe, and then load it into an electrospinning device for spinning; wherein the positive voltage of spinning is 15-20kV, the negative voltage is 15-20kV, the feed flow rate is 0.1-0.3mL / min, and the distance between the needle and the collector is 10-15cm. Step 4: The precursor nanofiber film collected on the collector is subjected to non-melting treatment at a temperature of 160–210°C. Step 5: Place the non-melting precursor fiber film in a carbon crucible, and then perform high-temperature heat treatment under a protective atmosphere. The heat treatment temperature is 700-1200℃, and the holding time is 3-5h to prepare TiO2 / Co / SiOC composite nanofiber film. The heating rate during the high-temperature heat treatment is 5-10℃ / min.

2. The composite nanofiber film according to claim 1, characterized in that: The organic solvent is a mixture of toluene, chloroform, or isopropanol with N,N-dimethylformamide, or a mixture of tetrahydrofuran or chloroform with xylene; wherein the volume ratio of toluene, chloroform, or isopropanol to N,N-dimethylformamide in the mixed solvent is (1-5):1; the volume ratio of tetrahydrofuran or chloroform to xylene is 1:(2-3); and the concentration of the SiOC precursor in the solution of step 1 is 0.075-0.225 g / ml.

3. The composite nanofiber film according to claim 1, characterized in that: The collector is a drum collector.

4. The composite nanofiber film according to claim 1, characterized in that: The inner diameter of the stainless steel needle is 0.51–1.69 mm.

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