Ti3C2 / TiO2 / CNF (at) Co / C aerogel as well as preparation method and application thereof
By preparing Ti3C2/TiO2/CNF@Co/C aerogel, the problems of narrow bandwidth and high density of traditional electromagnetic wave absorbing materials were solved, achieving broadband, lightweight and intelligently tunable electromagnetic wave absorption effects, which are suitable for complex electromagnetic environments.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-17
- Publication Date
- 2026-03-27
AI Technical Summary
Traditional electromagnetic wave absorbing materials suffer from narrow effective absorption bandwidth, high density, and limited functionality, failing to meet the demands of modern electronic devices for broadband, lightweight, and intelligently tunable absorption.
By preparing Ti3C2/TiO2/CNF@Co/C aerogel, Ti3C2 nanosheets were mixed with Co(NO3)2 and PAN using electrospinning and in-situ growth techniques to form a Ti3C2/TiO2/CNF@Co/C composite material. The aerogel was then formed by freeze-drying with sodium alginate, which enhanced the electromagnetic wave attenuation capability and reduced the filler content.
It achieves an ultra-wide effective absorption bandwidth (8.17 GHz) with extremely low filler content, and dynamically adjusts the absorption bandwidth (6.4–18 GHz) through compressive strain, adapting to complex electromagnetic environments and possessing excellent hydrophobicity, ductility and thermal insulation properties.
Smart Images
Figure CN121736700A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of microwave absorption, specifically relating to a Ti3C2 / TiO2 / CNF@Co / C tunable microwave absorbing aerogel, its preparation method, and its application. Background Technology
[0002] With the full deployment of fifth-generation mobile communication technology (5G) and the rapid popularization of electronic devices, human society has undergone revolutionary changes. However, the ensuing electromagnetic pollution now poses a serious challenge, endangering information security and public health. Traditional electromagnetic wave (EMW) absorbing materials face inherent limitations, including narrow effective absorption bandwidth (EAB), high density, and single function, failing to meet the urgent needs of modern electronic devices for broadband, lightweight, and intelligently tunable absorption. Therefore, the development of high-performance intelligent electromagnetic wave absorbing materials has become imperative.
[0003] Metal-organic framework (MOF)-derived carbon materials possess high specific surface area, hierarchical porous structure, and residual metal species (nanoparticles / oxides) after pyrolysis, which can enhance magnetic loss. However, single MOF derivatives are usually present in powder form, which inevitably leads to problems such as nanoparticle agglomeration and uneven distribution. Furthermore, their high filling amount and narrow bandgap also hinder microwave absorption as microwave absorbing materials. Summary of the Invention
[0004] To address the problems existing in the prior art, this invention provides a Ti3C2 / TiO2 / CNF@Co / C aerogel, its preparation method, and its applications. The aerogel prepared by this method exhibits excellent microwave absorption performance at extremely low filling amounts, and its EAB can be continuously adjusted within the compressive strain range of 6.4 to 18 GHz under different compressive strains.
[0005] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a method for preparing Ti3C2 / TiO2 / CNF@Co / C aerogel, comprising the following steps: S1, Co(NO3)2 6H2O, polyacrylonitrile (PAN) and Ti3C2 nanosheets were dispersed in N,N-dimethylformamide to obtain solution A; solution A was electrospun, and the resulting fibers were impregnated in 2-methylimidazole solution to grow ZIF67 in situ, thus obtaining Ti3C2 / PAN@ZIF67 fibers; S2, Ti3C2 / PAN@ZIF67 fibers are pre-oxidized and carbonized to obtain Ti3C2 / TiO2 / CNF@Co / C composite material; S3, multilayer Ti3C2 / TiO2 / CNF@Co / C composite materials are stacked and immersed in an aqueous solution containing sodium alginate, followed by freeze-drying to obtain Ti3C2 / TiO2. 2 / CNF@Co / C aerogel.
[0006] Preferably, in S1, the method for preparing Ti3C2 nanosheets is as follows: etching Ti3AlC2 powder to obtain initial Ti3C2 nanosheets; ultrasonically breaking the initial Ti3C2 nanosheets to obtain Ti3C2 nanosheets.
[0007] Specifically, the preparation method of Ti3C2 nanosheets includes: dissolving LiF in HCl to obtain solution A; dissolving Ti3AlC2 powder in solution A, stirring and reacting, and washing the resulting product to obtain initial Ti3C2 nanosheets; dispersing the initial Ti3C2 nanosheets in DMF to obtain solution B; placing solution B in an ultrasonic cell disruptor for ultrasonic disruption in an ice-water bath, and centrifuging the resulting product to obtain Ti3C2 nanosheets with uniform size and lateral dimensions of 300-500 nm that can be uniformly coated in PAN nanofibers.
[0008] Furthermore, in S3, the ultrasonic fragmentation power is 150–200 W, and the time is 4–5 h.
[0009] Preferably, in S1, Co(NO3)2 The mass ratio of 6H2O, PAN and Ti3C2 nanosheets was 1.2:1.0:(0.1~0.4).
[0010] Preferably, in S1, the conditions for electrospinning are: a positive voltage of 10–20 kV, a receiving distance of 10–15 cm between the syringe needle tip and the receiver, and a syringe propulsion rate of 0.04–0.06 mm / min.
[0011] Preferably, in S1, Co(NO3)2 The mass ratio of 6H2O to 2-methylimidazole is 1.2:4.0.
[0012] Preferably, in S1, the impregnation is carried out at room temperature for 16–24 hours.
[0013] Preferably, in S2, the pre-oxidation temperature is 240–260 °C and the time is 1–2 h; the carbonization temperature is 600–800 °C and the time is 1–2 h.
[0014] Preferably, in S3, the concentration of sodium alginate is 5–10 mg / mL.
[0015] Secondly, the present invention provides a Ti3C2 / TiO2 / CNF@Co / C aerogel obtained by the preparation method described above.
[0016] The Ti3C2 / TiO2 / CNF@Co / C aerogel includes carbon nanofibers, Ti3C2 / TiO2 nanosheets filled inside the carbon nanofibers, and hollow dodecahedral Co / C grown on the surface of the carbon nanofibers.
[0017] Thirdly, the present invention provides the application of the Ti3C2 / TiO2 / CNF@Co / C aerogel as a microwave absorbing material in electromagnetic wave absorption.
[0018] Compared with the prior art, the present invention has the following beneficial effects: This invention enhances the attenuation capability of electromagnetic waves and reduces the filler content of the composite material by constructing a composite of one-dimensional fibers, Ti3C2 / TiO2, and MOF derivatives. First, Ti3C2 nanosheets are combined with polyacrylonitrile powder and Co(NO3)2... PAN nanofibers encapsulating Ti3C2 nanosheets and loading Co were prepared by mixing with 6H2O. The resulting fibers were then immersed in a 2-methylimidazole (2-MI) solution. The reaction of 2-methylimidazole with cobalt ions in the fibers triggered the in-situ growth of dodecahedral ZIF67 on the fiber surface, forming smooth rhombic dodecahedrons uniformly covering the fiber surface. In the subsequent carbonization process, the PAN nanofibers were transformed into carbon nanofibers, Ti3C2 was partially oxidized to Ti3C2 / TiO2, and ZIF67 was transformed into a hollow dodecahedral Co / C framework. The formation of elemental Co significantly increased the magnetic loss capacity of the material. Although some structural collapse occurred, most of the hollow dodecahedral Co / C framework retained its dodecahedral morphology and surface adhesion. Multilayer fibers were stacked and impregnated in an aqueous solution of sodium alginate. Sodium alginate established multidimensional interactions with the Ti3C2 / TiO2 / CNF@Co / C fiber membrane through hydrogen bonding and electrostatic forces, strengthening the layered structure of the composite material, ultimately yielding a Ti3C2 / TiO2 / CNF@Co / C aerogel. The microwave absorbing material of this invention uses inexpensive and readily available raw materials, has a simple preparation method, and requires easy-to-operate equipment. It also boasts a high yield of fiber composite materials, making it a promising microwave absorbing material.
[0019] Furthermore, in order to ensure that the Ti3C2 powder is uniformly encapsulated within the PAN nanofibers, the Ti3C2 is peeled off into uniform nanosheets with a transverse size of 300-500 nm by etching and ultrasonic crushing.
[0020] This invention synergistically integrates a multi-level heterogeneous interface of Ti3C2 nanosheets, TiO2 nanoparticles, a magnetic Co / C framework, and carbon nanofibers through electrospinning and in-situ growth techniques. The electromagnetic wave absorption performance of the aerogel was tested using a vector network analyzer. The results showed that the optimized aerogel achieved an ultrawide effective absorption bandwidth (EAB) of 8.17 GHz with a thickness of only 2.7 mm and a filler loading of only 10 wt%. Its excellent hydrophobicity, ductility, and thermal insulation properties make it suitable for practical applications in various harsh environments. The addition of alginate-induced elastic aerogel network endows the material with excellent compressibility. By adjusting the internal air volume fraction under applied pressure to balance impedance matching, the elastic aerogel dynamically adjusts the EAB (6.4–18 GHz) within a strain range of 0–66%, thereby achieving real-time adaptability to complex electromagnetic environments. This invention provides an innovative strategy for designing intelligent adaptive electromagnetic wave absorbing materials, with broad application prospects in next-generation communication systems, electronic stealth technology, and electromagnetic shielding. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0022] Figure 1 The following are SEM images of the materials of the present invention: (a) SEM image of Ti3C2 / TiO2 / CNF@Co / C aerogel prepared in Example 1 of the present invention; (b) SEM image of Ti3C2 / TiO2 / CNF@Co / C aerogel prepared in Example 5; (c) SEM image of Ti3C2 / TiO2 / CNF@Co / C aerogel prepared in Example 8.
[0023] Figure 2 SEM images of the Ti3C2 / TiO2 / CNF and CNF@Co / C microwave absorbing materials prepared in Comparative Examples 1 and 2 are shown, where (a) is Comparative Example 1 and (b) is Comparative Example 2.
[0024] Figure 3 The image shows the XRD pattern of the Ti3C2 / TiO2 / CNF@Co / C tunable microwave absorbing aerogel prepared in Example 1 of this invention.
[0025] Figure 4 The reflection loss value is that of the Ti3C2 / TiO2 / CNF@Co / C tunable microwave absorbing aerogel prepared in Example 1 of this invention when the filling amount is 10 wt%.
[0026] Figure 5 The reflection loss value is that of CNF@Co / C tunable microwave absorbing aerogel prepared in Comparative Example 1 of this invention when the filling amount is 10wt%.
[0027] Figure 6 The values represent the reflection loss of the Ti3C2 / TiO2 / CNF@Co / C tunable microwave absorbing aerogel prepared in Example 1 of this invention under different compression ratios.
[0028] Figure 7 The dielectric loss and magnetic loss data of the Ti3C2 / TiO2 / CNF@Co / C tunable microwave absorbing aerogel prepared in Example 1 of this invention are shown below: (a) is the real part diagram of dielectric loss when the filling amount is 10 wt%; (b) is the imaginary part diagram of dielectric loss when the filling amount is 10 wt%; (c) is the real part diagram of magnetic loss when the filling amount is 10 wt%; and (d) is the imaginary part diagram of magnetic loss when the filling amount is 10 wt%.
[0029] Figure 8 The dielectric loss and magnetic loss data of the Ti3C2 / TiO2 / CNF@Co / C tunable microwave absorbing aerogel prepared in Example 1 of this invention under different compression ratios: (a) Real part diagram of dielectric loss; (b) Imaginary part diagram of dielectric loss; (c) Real part diagram of magnetic loss; (d) Imaginary part diagram of magnetic loss. Detailed Implementation
[0030] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0031] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.
[0032] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not intended to limit the order of the method steps or define the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.
[0033] Example 1: A method for preparing a Ti3C2 / TiO2 / CNF@Co / C tunable microwave-absorbing aerogel includes the following steps: (1) First, 3.2 g of LiF was dissolved in 40 mL of 9 M HCl under vigorous stirring, followed by the slow addition of 2 g of Ti3AlC2 precursor powder. The resulting mixture was continuously stirred in a 40 °C water bath for 24 h to ensure complete etching. Then, the etched product was washed with 4 M HCl (washed twice, 1 min each time) to remove residual LiF, followed by repeated rinsing with deionized water (1 min each time) until the supernatant darkened. The suspension was centrifuged at 3500 rpm / min for 15 min, and the supernatant was collected. Finally, the collected supernatant was freeze-dried at -50 °C for 48 h to obtain a few-layer Ti3C2 powder; (2) To ensure that Ti3C2 is uniformly dispersed in PAN nanofibers, 0.4 g of Ti3C2 powder was dispersed in 50 mL of deionized water and ultrasonically treated in an ice-water bath at 150 W for 5 h using an ultrasonic cell disruptor. The suspension was then centrifuged at 9000 rpm for 20 min to collect Ti3C2 nanosheets.
[0034] (3) 0.4 g of collected Ti3C2 nanosheets, 1.2 g of Co(NO3)2·6H2O, and 1.0 g of PAN were added sequentially to 10 mL of DMF. The resulting mixture was magnetically stirred at 60 °C for 12 h until a uniform deep purple solution was formed. Specific parameters were set during the electrospinning process: the positive voltage was set to 20 kV, the receiving distance was controlled at 10 cm, the needle size was 18, and the feed rate was set to 0.04 mm / min. Finally, the Ti3C2 / PAN@Co(NO3)2 nanofibers were collected on an aluminum foil substrate and dried at 60 °C for later use.
[0035] (4) Ti3C2 / PAN@Co(NO3)2 nanofibers were immersed in 100 mL of methanol containing 4.0 g 2-MI and kept at room temperature for 24 h. Then, the obtained Ti3C2 / PAN@ZIF-67 nanofibers were thoroughly washed with methanol and pre-oxidized at 260 °C for 1 h. Finally, the pre-oxidized nanofibers were carbonized in a tube furnace at 800 °C for 2 h under an argon atmosphere, with a heating rate of 2 °C / min, to obtain Ti3C2 / TiO2 / CNF@Co / C. In addition, 100 mg of Ti3C2 / TiO2 / CNF@Co / C were stacked and immersed in 0.5 wt% sodium alginate solution for 30 min and then freeze-dried to form an elastic aerogel.
[0036] Example 2: A method for preparing a Ti3C2 / TiO2 / CNF@Co / C tunable microwave-absorbing aerogel includes the following steps: (1) First, 3.2 g of LiF was dissolved in 40 mL of 9 M HCl under vigorous stirring, followed by the slow addition of 2 g of Ti3AlC2 precursor powder. The resulting mixture was continuously stirred in a 40 °C water bath for 24 h to ensure complete etching. Then, the etched product was washed with 4 M HCl (washed 3 times, 1 min each time) to remove residual LiF, followed by repeated rinsing with deionized water (1 min each time) until the supernatant darkened. The suspension was centrifuged at 3500 rpm / min for 15 min, and the supernatant was collected. Finally, the collected supernatant was freeze-dried at -50 °C for 48 h to obtain a few-layer Ti3C2T x powder; (2) To ensure that Ti3C2 is uniformly dispersed in PAN nanofibers, 0.2 g of Ti3C2 powder was dispersed in 50 mL of deionized water and ultrasonically treated in an ice-water bath at 150 W for 4 h using an ultrasonic cell disruptor. The suspension was then centrifuged at 9000 rpm for 20 min to collect Ti3C2 nanosheets.
[0037] (3) The collected Ti3C2 nanosheets, 1.2 g Co(NO3)2·6H2O, and 1.0 g PAN were added sequentially to 10 mL of DMF. The mixture was magnetically stirred at 60 °C for 8 h until a uniform deep purple solution was formed. Specific parameters were set during the electrospinning process: the positive voltage was set to 15 kV, the receiving distance was controlled at 10 cm, the needle size was 20, and the feed rate was set to 0.06 mm / min. Finally, the Ti3C2 / PAN@Co(NO3)2 nanofibers were collected on an aluminum foil substrate and dried at 60 °C for later use.
[0038] (4) Ti3C2 / PAN@Co(NO3)2 nanofibers were immersed in 100 mL of methanol containing 4.0 g 2-MI and kept at room temperature for 24 h. Then, Ti3C2 / PAN@ZIF-67 nanofibers were thoroughly washed with methanol and pre-oxidized at 260 °C for 1 h. Finally, the pre-oxidized nanofibers were carbonized in a tube furnace at 700 °C for 2 h under an argon atmosphere, with a heating rate of 2 °C / min, to obtain Ti3C2 / TiO2 / CNF@Co / C. In addition, 100 mg of Ti3C2 / TiO2 / CNF@Co / C were stacked and immersed in 0.5 wt% sodium alginate solution for 30 min and then freeze-dried to form an elastic aerogel.
[0039] Example 3: A method for preparing a Ti3C2 / TiO2 / CNF@Co / C tunable microwave-absorbing aerogel includes the following steps: (1) First, 3.2 g of LiF was dissolved in 40 mL of 9 M HCl under vigorous stirring, followed by the slow addition of 2 g of Ti3AlC2 precursor powder. The mixture was continuously stirred in a water bath at 40 °C for 24 h to ensure complete etching. Then, the etched product was washed with 4 M HCl (washed twice, 1 min each time) to remove residual LiF, followed by repeated rinsing with deionized water (1 min each time) until the supernatant darkened. The suspension was centrifuged at 3500 rpm / min for 15 min, and the supernatant was collected. Finally, the collected supernatant was freeze-dried at -50 °C for 48 h to obtain a few-layer Ti3C2T x powder.
[0040] (2) To ensure that Ti3C2 is uniformly dispersed in PAN nanofibers, 0.1 g of Ti3C2 powder was dispersed in 50 mL of deionized water and ultrasonically treated in an ice-water bath at 150 W for 3 h using an ultrasonic cell disruptor. The suspension was then centrifuged at 9000 rpm for 20 min to collect Ti3C2 nanosheets.
[0041] (3) The collected Ti3C2 nanosheets, 1.2 g Co(NO3)2·6H2O, and 1.0 g PAN were added sequentially to 10 mL of DMF. The resulting mixture was magnetically stirred at 60 °C for 4 h until a uniform deep purple solution was formed. Specific parameters were set during the electrospinning process: the positive voltage was set to 12 kV, the receiving distance was controlled at 10 cm, the needle type was No. 21, and the feed rate was set to 0.08 mm / min. Finally, the Ti3C2 / PAN@Co(NO3)2 nanofibers were collected on an aluminum foil substrate and dried at 60 °C for later use.
[0042] (4) Ti3C2 / PAN@Co(NO3)2 nanofibers were immersed in 100 mL of methanol containing 4.0 g 2-MI and kept at room temperature for 12 h. Then, Ti3C2 / PAN@ZIF-67 nanofibers were thoroughly washed with methanol and pre-oxidized at 280 °C for 1 h. Finally, the pre-oxidized nanofibers were carbonized in a tube furnace at 600 °C for 2 h under an argon atmosphere, with a heating rate of 2 °C / min, to obtain Ti3C2 / TiO2 / CNF@Co / C. In addition, 100 mg of Ti3C2 / TiO2 / CNF@Co / C were stacked and immersed in 0.5 wt% sodium alginate solution for 30 min and then freeze-dried to form an elastic aerogel.
[0043] Example 4: A method for preparing a Ti3C2 / TiO2 / CNF@Co / C tunable microwave-absorbing aerogel includes the following steps: (1) First, 2.6 g of LiF was dissolved in 40 mL of 9M HCl under vigorous stirring, followed by the slow addition of 2 g of Ti3AlC2 precursor powder. The resulting mixture was continuously stirred in a 40 °C water bath for 36 h to ensure complete etching. Then, the etched product was washed with 2M HCl (washed twice, 1 min each time) to remove residual LiF, followed by repeated rinsing with deionized water (1 min each time) until the supernatant darkened. The suspension was centrifuged at 3500 rpm / min for 15 min, and the supernatant was collected. Finally, the collected supernatant was freeze-dried at -50 °C for 48 h to obtain a few-layer Ti3C2T x powder.
[0044] (2) To ensure that Ti3C2 is uniformly dispersed in PAN nanofibers, 0.4 g of Ti3C2 powder was dispersed in 50 mL of deionized water and ultrasonically treated in an ice-water bath at 150 W power for 5 h using an ultrasonic cell disruptor. The suspension was then centrifuged at 9000 rpm for 20 min to collect Ti3C2 nanosheets.
[0045] (3) The collected Ti3C2 nanosheets, 1.2 g Co(NO3)2·6H2O, and 1.0 g PAN were added sequentially to 10 mL of DMF. The resulting mixture was magnetically stirred at 60 °C for 12 h until a uniform deep purple solution was formed. Specific parameters were set during the electrospinning process: the positive voltage was set to 20 kV, the receiving distance was controlled at 10 cm, the needle size was 18, and the feed rate was set to 0.04 mm / min. Finally, the Ti3C2 / PAN@Co(NO3)2 nanofibers were collected on an aluminum foil substrate and dried at 60 °C for later use.
[0046] (4) Ti3C2 / PAN@Co(NO3)2 nanofibers were immersed in 100 mL of methanol containing 4.0 g 2-MI and kept at room temperature for 24 h. Then, Ti3C2 / PAN@ZIF-67 nanofibers were thoroughly washed with methanol and pre-oxidized at 240 °C for 2 h. Finally, the pre-oxidized nanofibers were carbonized in a tube furnace at 800 °C for 2 h under an argon atmosphere, with a heating rate of 2 °C / min, to obtain Ti3C2 / TiO2 / CNF@Co / C. In addition, 100 mg of Ti3C2 / TiO2 / CNF@Co / C were stacked and immersed in 0.5 wt% sodium alginate solution for 30 min and then freeze-dried to form an elastic aerogel.
[0047] Example 5: A method for preparing a Ti3C2 / TiO2 / CNF@Co / C tunable microwave-absorbing aerogel includes the following steps: (1) First, 2.6 g of LiF was dissolved in 40 mL of 9M HCl under vigorous stirring, followed by the slow addition of 2 g of Ti3AlC2 precursor powder. The resulting mixture was continuously stirred in a 40 °C water bath for 36 h to ensure complete etching. Then, the etched product was washed with 2M HCl (washed twice, 1 min each time) to remove residual LiF, followed by repeated rinsing with deionized water (1 min each time) until the supernatant darkened. The suspension was centrifuged at 3500 rpm / min for 15 min, and the supernatant was collected. This process could be repeated if necessary. Finally, the collected supernatant was freeze-dried at -50 °C for 48 h to obtain a few-layer Ti3C2T x powder.
[0048] (2) To ensure that Ti3C2 is uniformly dispersed in PAN nanofibers, 0.2 g of Ti3C2 powder was dispersed in 50 mL of deionized water and ultrasonically treated in an ice-water bath at 150 W for 4 h using an ultrasonic cell disruptor. The suspension was then centrifuged at 9000 rpm for 20 min to collect Ti3C2 nanosheets.
[0049] (3) The collected Ti3C2 nanosheets, 1.2 g Co(NO3)2·6H2O, and 1.0 g PAN were added sequentially to 10 mL of DMF. The resulting mixture was magnetically stirred at 60 °C for 8 h until a uniform deep purple solution was formed. Specific parameters were set during the electrospinning process: the positive voltage was set to 15 kV, the receiving distance was controlled at 10 cm, the needle size was 20, and the feed rate was set to 0.06 mm / min. Finally, the Ti3C2 / PAN@Co(NO3)2 nanofibers were collected on an aluminum foil substrate and dried at 60 °C for later use.
[0050] (4) Ti3C2 / PAN@Co(NO3)2 nanofibers were immersed in 100 mL of methanol containing 4.0 g 2-MI and kept at room temperature for 12 h. Then, Ti3C2 / PAN@ZIF-67 nanofibers were thoroughly washed with methanol and pre-oxidized at 240 °C for 2 h. Finally, the pre-oxidized nanofibers were carbonized in a tube furnace at 700 °C for 2 h under an argon atmosphere, with a heating rate of 2 °C / min, to obtain Ti3C2 / TiO2 / CNF@Co / C. In addition, 100 mg of Ti3C2 / TiO2 / CNF@Co / C were stacked and immersed in 0.5 wt% sodium alginate solution for 30 min and then freeze-dried to form an elastic aerogel.
[0051] Example 6: A method for preparing a Ti3C2 / TiO2 / CNF@Co / C tunable microwave-absorbing aerogel includes the following steps: (1) First, 2.6 g of LiF was dissolved in 40 mL of 9M HCl under vigorous stirring, followed by the slow addition of 2 g of Ti3AlC2 precursor powder. The mixture was continuously stirred in a 40 °C water bath for 36 h to ensure complete etching. Then, the etched product was washed with 2M HCl (washed twice, 1 min each time) to remove residual LiF, followed by repeated rinsing with deionized water (1 min each time) until the supernatant darkened. The suspension was centrifuged at 3500 rpm / min for 15 min, and the supernatant was collected. This process could be repeated if necessary. Finally, the collected supernatant was freeze-dried at -50 °C for 48 h to obtain a few-layer Ti3C2Tx powder.
[0052] (2) To ensure that Ti3C2 is uniformly dispersed in PAN nanofibers, 0.1 g of Ti3C2 powder was dispersed in 50 mL of deionized water and ultrasonically treated in an ice-water bath at 150 W for 3 h using an ultrasonic cell disruptor. The suspension was then centrifuged at 9000 rpm for 20 min to collect Ti3C2 nanosheets.
[0053] (3) The collected Ti3C2 nanosheets, 1.2 g Co(NO3)2·6H2O, and 1.0 g PAN were added sequentially to 10 mL of DMF. The resulting mixture was magnetically stirred at 60 °C for 4 h until a uniform deep purple solution was formed. Specific parameters were set during the electrospinning process: the positive voltage was set to 12 kV, the receiving distance was controlled at 10 cm, the needle type was No. 21, and the feed rate was set to 0.08 mm / min. Finally, the Ti3C2 / PAN@Co(NO3)2 nanofibers were collected on an aluminum foil substrate and dried at 60 °C for later use.
[0054] (4) Ti3C2 / PAN@Co(NO3)2 nanofibers were immersed in 100 mL of methanol containing 4.0 g 2-MI and kept at room temperature for 24 h. Then, Ti3C2 / PAN@ZIF-67 nanofibers were thoroughly washed with methanol and pre-oxidized at 240 °C for 2 h. Finally, the pre-oxidized nanofibers were carbonized in a tube furnace at 600 °C for 2 h under an argon atmosphere, with a heating rate of 2 °C / min, to obtain Ti3C2 / TiO2 / CNF@Co / C. In addition, 100 mg of Ti3C2 / TiO2 / CNF@Co / C were stacked and immersed in 0.5 wt% sodium alginate solution for 30 min and then freeze-dried to form an elastic aerogel.
[0055] Example 7: A method for preparing a Ti3C2 / TiO2 / CNF@Co / C tunable microwave-absorbing aerogel includes the following steps: (1) First, 2 g of LiF was dissolved in 40 mL of 9 M HCl under vigorous stirring, followed by the slow addition of 2 g of Ti3AlC2 precursor powder. The resulting mixture was continuously stirred in a 40 °C water bath for 48 h to ensure complete etching. Then, residual LiF was removed by repeated rinsing with deionized water (1 min each time) until the supernatant darkened. The suspension was centrifuged at 3500 rpm / min for 15 min, and the supernatant was collected. Finally, the collected supernatant was freeze-dried at -50 °C for 48 h to obtain a few-layer Ti3C2T xpowder.
[0056] (2) To ensure that Ti3C2 is uniformly dispersed in PAN nanofibers, 0.4 g of Ti3C2 powder was dispersed in 50 mL of deionized water and ultrasonically treated in an ice-water bath at 150 W for 5 h using an ultrasonic cell disruptor. The suspension was then centrifuged at 9000 rpm for 20 min to collect Ti3C2 nanosheets.
[0057] (3) The collected Ti3C2 nanosheets, 1.2 g Co(NO3)2·6H2O, and 1.0 g PAN were added sequentially to 10 mL of DMF. The mixture was magnetically stirred at 60 °C for 12 h until a uniform deep purple solution was formed. Specific parameters were set during the electrospinning process: the positive voltage was set to 20 kV, the receiving distance was controlled at 10 cm, the needle size was 18, and the feed rate was set to 0.04 mm / min. Finally, the Ti3C2 / PAN@Co(NO3)2 nanofibers were collected on an aluminum foil substrate and dried at 60 °C for later use.
[0058] (4) Ti3C2 / PAN@Co(NO3)2 nanofibers were immersed in 100 mL of methanol containing 4.0 g 2-MI and kept at room temperature for 12 h. Then, Ti3C2 / PAN@ZIF-67 nanofibers were thoroughly washed with methanol and pre-oxidized at 200 °C for 2 h. Finally, the pre-oxidized nanofibers were carbonized in a tube furnace at 800 °C for 2 h under an argon atmosphere, with a heating rate of 2 °C / min, to obtain Ti3C2 / TiO2 / CNF@Co / C. In addition, 100 mg of Ti3C2 / TiO2 / CNF@Co / C were stacked and immersed in 0.5 wt% sodium alginate solution for 30 min and then freeze-dried to form an elastic aerogel.
[0059] Example 8: A method for preparing a Ti3C2 / TiO2 / CNF@Co / C tunable microwave-absorbing aerogel includes the following steps: (1) First, 2 g of LiF was dissolved in 40 mL of 9 M HCl under vigorous stirring, followed by the slow addition of 2 g of Ti3AlC2 precursor powder. The mixture was continuously stirred in a 40 °C water bath for 48 h to ensure complete etching. Then, residual LiF was removed by repeated rinsing with deionized water (1 min each time) until the supernatant darkened. The suspension was centrifuged at 3500 rpm / min for 15 min, and the supernatant was collected. Finally, the collected supernatant was freeze-dried at -50 °C for 48 h to obtain a few-layer Ti3C2T x powder; (2) To ensure that Ti3C2 is uniformly dispersed in PAN nanofibers, 0.2 g of Ti3C2 powder was dispersed in 50 mL of deionized water and ultrasonically treated in an ice-water bath at 150 W for 4 h using an ultrasonic cell disruptor. The suspension was then centrifuged at 9000 rpm for 20 min to collect Ti3C2 nanosheets.
[0060] (3) The collected Ti3C2 nanosheets, 1.2 g Co(NO3)2·6H2O, and 1.0 g PAN were added sequentially to 10 mL of DMF. The mixture was magnetically stirred at 60 °C for 8 h until a uniform deep purple solution was formed. Specific parameters were set during the electrospinning process: the positive voltage was set to 15 kV, the receiving distance was controlled at 10 cm, the needle size was 20, and the feed rate was set to 0.06 mm / min. Finally, the Ti3C2 / PAN@Co(NO3)2 nanofibers were collected on an aluminum foil substrate and dried at 60 °C for later use.
[0061] (4) Ti3C2 / PAN@Co(NO3)2 nanofibers were immersed in 100 mL of methanol containing 4.0 g 2-MI and kept at room temperature for 24 h. Then, Ti3C2 / PAN@ZIF-67 nanofibers were thoroughly washed with methanol and pre-oxidized at 200 °C for 2 h. Finally, the pre-oxidized nanofibers were carbonized in a tube furnace at 700 °C for 2 h under an argon atmosphere, with a heating rate of 2 °C / min, to obtain Ti3C2 / TiO2 / CNF@Co / C. In addition, 100 mg of Ti3C2 / TiO2 / CNF@Co / C were stacked and immersed in 0.5 wt% sodium alginate solution for 30 min and then freeze-dried to form an elastic aerogel.
[0062] Example 9: A method for preparing a Ti3C2 / TiO2 / CNF@Co / C tunable microwave-absorbing aerogel includes the following steps: (1) First, 2 g of LiF was dissolved in 40 mL of 9 M HCl under vigorous stirring, followed by the slow addition of 2 g of Ti3AlC2 precursor powder. The resulting mixture was continuously stirred in a 40 °C water bath for 48 h to ensure complete etching. Then, residual LiF was removed by repeated rinsing with deionized water (1 min each time) until the supernatant darkened. The suspension was centrifuged at 3500 rpm / min for 15 min, and the supernatant was collected. This process could be repeated if necessary. Finally, the collected supernatant was freeze-dried at -50 °C for 48 h to obtain a few-layer Ti3C2T x powder; (2) To ensure that Ti3C2 is uniformly dispersed in PAN nanofibers, 0.1 g of Ti3C2 powder was dispersed in 50 mL of deionized water and ultrasonically treated in an ice-water bath at 150 W for 3 h using an ultrasonic cell disruptor. The suspension was then centrifuged at 9000 rpm for 20 min to collect Ti3C2 nanosheets.
[0063] (3) The collected Ti3C2 nanosheets, 1.2 g Co(NO3)2·6H2O, and 1.0 g PAN were added sequentially to 10 mL of DMF. The resulting mixture was magnetically stirred at 60 °C for 4 h until a uniform deep purple solution was formed. Specific parameters were set during the electrospinning process: the positive voltage was set to 12 kV, the receiving distance was controlled at 10 cm, the needle type was No. 21, and the feed rate was set to 0.08 mm / min. Finally, the Ti3C2 / PAN@Co(NO3)2 nanofibers were collected on an aluminum foil substrate and dried at 60 °C for later use.
[0064] (4) Ti3C2 / PAN@Co(NO3)2 nanofibers were immersed in 100 mL of methanol containing 4.0 g 2-MI and kept at room temperature for 24 h. Then, Ti3C2 / PAN@ZIF-67 nanofibers were thoroughly washed with methanol and pre-oxidized at 200 °C for 2 h. Finally, the pre-oxidized nanofibers were carbonized in a tube furnace at 600 °C for 2 h under an argon atmosphere, with a heating rate of 2 °C / min, to obtain Ti3C2 / TiO2 / CNF@Co / C. In addition, 100 mg of Ti3C2 / TiO2 / CNF@Co / C were stacked and immersed in 0.5 wt% sodium alginate solution for 30 min and then freeze-dried to form an elastic aerogel.
[0065] Comparative Example 1: A method for preparing a Ti3C2 / TiO2 / CNF microwave absorbing material includes the following steps: (1) First, 3.2 g of LiF was dissolved in 40 mL of 9 M HCl under vigorous stirring, followed by the slow addition of 2 g of Ti3AlC2 precursor powder. The resulting mixture was continuously stirred in a 40 °C water bath for 24 h to ensure complete etching. Then, the etched product was washed with 4 M HCl (washed twice, 1 min each time) to remove residual LiF, followed by repeated rinsing with deionized water (1 min each time) until the supernatant darkened. The suspension was centrifuged at 3500 rpm / min for 15 min, and the supernatant was collected. Finally, the collected supernatant was freeze-dried at -50 °C for 48 h to obtain a few-layer Ti3C2T x powder; (2) To ensure that Ti3C2 is uniformly dispersed in PAN nanofibers, 0.4 g of Ti3C2 powder was dispersed in 50 mL of deionized water and ultrasonically treated in an ice-water bath at 150 W for 5 h using an ultrasonic cell disruptor. The suspension was then centrifuged at 9000 rpm for 20 min to collect Ti3C2 nanosheets.
[0066] (3) The collected Ti3C2 nanosheets and 1.0 g PAN were added sequentially to 10 mL of DMF. The mixture was magnetically stirred at 60 °C for 12 h until a uniform black solution was formed. Specific parameters were set during the electrospinning process: the positive voltage was set to 15 kV, the receiving distance was controlled at 10 cm, the needle type was No. 21, and the feed rate was set to 0.06 mm / min. Finally, the Ti3C2 / PAN nanofibers were collected on an aluminum foil substrate and dried at 60 °C for later use.
[0067] (4) The Ti3C2 / PAN nanofibers were pre-oxidized at 260 °C for 1 h. Finally, the pre-oxidized nanofibers were carbonized in a tube furnace at 700 °C for 2 h under an argon atmosphere, with a heating rate of 2 °C / min, to obtain Ti3C2 / TiO2 / CNF.
[0068] Comparative Example 2: A method for preparing CNF@Co / C microwave absorbing material includes the following steps: (1) 1.2 g Co(NO3)2·6H2O and 1.0 g PAN were added sequentially to 10 mL DMF. The resulting mixture was magnetically stirred at 60 °C for 12 h until a uniform pink solution was formed. Specific parameters were set during the electrospinning process: positive voltage was set to 20 kV, receiving distance was controlled at 10 cm, needle type was 21, and feed rate was set to 0.06 mm / min. Finally, the PAN@Co(NO3)2 nanofibers were collected on an aluminum foil substrate and dried at 60 °C for later use.
[0069] (4) PAN@Co(NO3)2 nanofibers were immersed in 100 mL of methanol containing 4.0 g 2-MI and kept at room temperature for 24 h. Then, PAN@ZIF-67 nanofibers were thoroughly washed with methanol and pre-oxidized at 260 °C for 1 h. Finally, the pre-oxidized nanofibers were carbonized in a tube furnace at 800 °C for 2 h under an argon atmosphere, with a heating rate of 2 °C / min, to obtain CNF@Co / C.
[0070] Figure 1SEM images of the Ti3C2 / TiO2 / CNF@Co / C tunable microwave-absorbing aerogels prepared in Examples 1, 5, and 8 are shown, where (a) is Example 1, (b) is Example 5, and (c) is Example 8. As can be seen from the images, the metal-organic framework-derived Co / C dodecahedrons are densely and uniformly distributed on the one-dimensional carbon fibers.
[0071] Figure 2 SEM images of the Ti3C2 / TiO2 / CNF and CNF@Co / C microwave absorbing materials prepared in Comparative Examples 1 and 2 are shown. (a) is Comparative Example 1 and (b) is Comparative Example 2. As can be seen from the images, Ti3C2 / TiO2 nanosheets are uniformly distributed inside the one-dimensional carbon fiber, and the outer shell Co / C dodecahedrons are densely and uniformly distributed on the one-dimensional carbon fiber.
[0072] Figure 3 The XRD pattern of the Ti3C2 / TiO2 / CNF@Co / C tunable microwave absorbing aerogel prepared in the best-performing example (Example 1) is shown, indicating the presence of Ti3C2, TiO2 and Co particles in the material.
[0073] Figure 4 The reflection loss diagram of the Ti3C2 / TiO2 / CNF@Co / C tunable microwave absorbing aerogel prepared in the optimal embodiment of the present invention (Example 1) at a filling amount of 10 wt%. With a matching thickness of 2.6 mm, the Ti3C2 / TiO2 / CNF@Co / C microwave absorbing aerogel exhibits a reflection loss of -40.7 dB, and achieves a maximum effective absorption bandwidth of 8.17 GHz with a thickness of 2.7 mm.
[0074] Figure 5 The image shows the reflection loss of the CNF@Co / C microwave absorbing material prepared in Comparative Example 2 of this invention at a filling amount of 10 wt%. The CNF@Co / C microwave absorbing material achieved a reflection loss of -10.44 dB and a maximum effective absorption bandwidth of 2.12 GHz. The only difference between Comparative Example 2 and Example 1 is the absence of Ti3C2 / TiO2, resulting in fewer heterostructures and poorer impedance matching in the obtained microwave absorbing material. Figure 5 Comparing Example 1 and Comparative Example 2, it can be seen that the microwave absorbing material of Comparative Example 2 has a weaker reflection loss than that of Example 1. This indicates that the addition of Ti3C2 / TiO2 increases the variety of components, optimizes impedance matching, and constructs a rich heterogeneous interface, which is beneficial for improving interface polarization and dissipating electromagnetic waves.
[0075] Figure 6The diagram shows the reflection loss of the Ti3C2 / TiO2 / CNF@Co / C tunable microwave absorbing aerogel prepared in Example 1 under different compression ratios. At different compression ratios, the effective absorption bandwidth covers 11.2 GHz, exhibiting excellent microwave absorption performance. Comparing the effective absorption bandwidth of the aerogel material at different compression ratios shows that the aerogel material of Example 1 has tunable microwave absorption performance, indicating that the alginate-induced elastic aerogel can dynamically adjust the electromagnetic wave absorption bandwidth by changing the electromagnetic parameters through compression. Figure 7 (a) shows the real part of the dielectric loss of the Ti3C2 / TiO2 / CNF@Co / C tunable microwave absorbing aerogel prepared in the best-performing embodiment of the present invention (Example 1). In the 2-18 GHz range, the real part of the dielectric loss decreases from 7.9 to 3.7, showing an overall decreasing trend. Figure 7 Figure (b) shows the imaginary part of the dielectric loss of the Ti3C2 / TiO2 / CNF@Co / C tunable microwave absorbing aerogel prepared in the best-performing embodiment of the present invention (Example 1). The curve shows a certain degree of fluctuation in the high-frequency band, indicating the synergistic effect of multiple polarization mechanisms in this frequency band. Figure 7 (c) is the real part of the magnetic loss of the Ti3C2 / TiO2 / CNF@Co / C tunable microwave absorbing aerogel prepared in the best-performing embodiment of the present invention (Example 1); the real part value fluctuates to a certain extent throughout the entire frequency range, and the fluctuation gradually decreases with the increase of frequency. Figure 7 In Figure (d), the imaginary part of the magnetic loss of the Ti3C2 / TiO2 / CNF@Co / C tunable microwave absorbing aerogel prepared in the best-performing embodiment of the present invention (Example 1) is shown. It can be seen that the magnetic loss capability gradually decreases with increasing frequency.
[0076] Figure 8 Figure (a) shows the real part of dielectric loss of the Ti3C2 / TiO2 / CNF@Co / C tunable microwave absorbing aerogel prepared in Example 1 of this invention under different compression ratios. In the range of 2-18 GHz, the real part of dielectric loss generally increases with the increase of compression ratio. Figure 8 (b) shows the imaginary part of dielectric loss for the Ti3C2 / TiO2 / CNF@Co / C tunable microwave absorbing aerogel prepared in Example 1 of this invention under different compression ratios. Its overall trend is similar to that of the real part of dielectric loss. Figure 8 Image (c) shows the real part of the magnetic loss of the Ti3C2 / TiO2 / CNF@Co / C tunable microwave absorbing aerogel prepared in Example 1 of this invention under different compression ratios. In the range of 2-18 GHz, the overall trend of the real part of the magnetic loss remains basically unchanged as the compression ratio increases. Figure 8In Figure (d), the imaginary part of magnetic loss is shown under different compression ratios for the Ti3C2 / TiO2 / CNF@Co / C tunable microwave absorbing aerogel prepared in Example 1 of this invention. Within the 2-18 GHz range, the overall trend of the imaginary part of magnetic loss remains essentially unchanged as the compression ratio increases.
[0077] The Ti3C2 / TiO2 / CNF@Co / C tunable microwave absorbing aerogel prepared in this invention exhibits excellent microwave absorption performance and can achieve tunable electromagnetic wave absorption bandwidth under different compression ratios. This is because: firstly, numerous heterogeneous interfaces are formed between Ti3C2 / TiO2, Co / C, and CNF, where charges accumulate under an external electromagnetic field. As the field changes alternately, the interface charges accumulate and redistribute. The synergistic effect of multiple loss mechanisms and optimized impedance matching is a key factor in the excellent electromagnetic absorption performance of TTCFC. Notably, the combination of sodium alginate-induced elastic aerogel network imparts a high compression recovery rate, enabling the adjustment of the internal air volume fraction under different compressions to optimize impedance matching. This structural and electromagnetic parameter change caused by compression ultimately achieves dynamic electromagnetic absorption of the material. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.
Claims
1. A preparation method of a Ti3C2 / TiO2 / CNF@Co / C aerogel, characterized in that, The method comprises the following steps: S1, Co(NO3)2 6H2O, PAN and Ti3C2nanosheets were dispersed in N, N-dimethylformamide to obtain solution A; solution A was electrospun, and the obtained fiber was immersed in a 2-methylimidazole solution to obtain Ti3C2 / PAN@ZIF67 fiber; S2, pre-oxidizing and carbonizing the Ti3C2 / PAN@ZIF67 fiber to obtain a Ti3C2 / TiO2 / CNF@Co / C composite material; S3, the multi-layer Ti3C2 / TiO2 / CNF@Co / C composite material is stacked layer by layer and immersed in a water solution containing sodium alginate, freeze-dried to obtain Ti3C2 / TiO 2 / CNF@Co / C aerogel.
2. The preparation method of Ti3C2 / TiO2 / CNF@Co / C aerogel according to claim 1, characterized in that, In S1, the Ti3C2 nanosheet is prepared by etching Ti3AlC2 powder to obtain initial Ti3C2 nanosheet, and then performing ultrasonic crushing to obtain the Ti3C2 nanosheet.
3. The method for preparing Ti3C2 / TiO2 / CNF@Co / C aerogel according to claim 2, characterized in that, In S3, the ultrasonic crushing power is 150-200 W, and the time is 4-5 h. 4.The method of claim 1, wherein the Ti 3C 2 / TiO 2 / CNF@Co / C aerogel is prepared by the steps of, S1, Co(N03)2 6H20, PAN and Ti3C2nanosheets in a mass ratio of 1.2:1.0:(0.1-0.4). 5.The method of claim 1, wherein the Ti 3C 2 / TiO 2 / CNF@Co / C aerogel is prepared by the steps of, In S1, the electrostatic spinning condition is that the positive voltage is 10-20 kV, the receiving distance between the needle tip of the injector and the receiver is 10-15 cm, and the advancing speed of the injector is 0.04-0.06 mm / min. 6.The method of claim 1, wherein the Ti 3C 2 / TiO 2 / CNF@Co / C aerogel is prepared by the steps of, In S1, Co(N03)2 6H20 to 2-methylimidazole was 1.2:4.
0. 7.The method of claim 1, wherein the Ti 3C 2 / TiO 2 / CNF@Co / C aerogel is prepared by the steps of, In S2, the pre-oxidation temperature is 240-260 DEG C, and the time is 1-2 h; the carbonization temperature is 600-800 DEG C, and the time is 1-2 h. 8.The method of claim 1, wherein the Ti 3C 2 / TiO 2 / CNF@Co / C aerogel is prepared by the steps of, In S3, the concentration of sodium alginate is 5-10 mg / mL.
9. The Ti3C2 / TiO2 / CNF@Co / C aerogel obtained by the preparation method in any one of claims 1-8.
10. Application of the Ti3C2 / TiO2 / CNF@Co / C aerogel in claim 9 as a wave-absorbing material in electromagnetic wave absorption.