A sheath-like nanofiber containing hydrogenated graphdiyne and a preparation method thereof

Abstract

The application provides a hydrogenated graphdiyne-containing sleeve-shaped nanofiber and a preparation method thereof, and the hydrogenated graphdiyne-containing sleeve-shaped nanofiber is prepared by using MnO2 nanowires as a template, Glaser coupling reaction of 1,3,5-triethynylbenzene and oxidation self-polymerization reaction of dopamine (DA) in a weak alkaline solution, uniformly coating hydrogenated graphdiyne (HsGDY) and polydopamine (PDA) on the surface of the MnO2 nanowires in sequence, then removing the hard template MnO2 nanowires through oxalic acid etching, and then obtaining HsGDY@NC nanotubes through high-temperature calcination.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wave-absorbing materials, and particularly relates to a sleeve-shaped nanofiber containing hydrogenated graphdiyne and a preparation method thereof. BACKGROUND

[0002] Nanomaterials are materials that have at least one dimension in the nanometer range (1-100 nm) or are composed of such basic units. They exhibit significant surface and interface effects, small size effects, and unique mechanical, electrical, optical, magnetic, and thermal properties, which are different from those of traditional solid materials. Among them, one-dimensional nanomaterials have attracted widespread attention due to the following characteristics: first, one-dimensional materials have good dispersion properties, providing a conductive path for the rapid transmission of electrons; second, due to their large aspect ratio, they effectively enhance the absorption and scattering properties of light; finally, one-dimensional nanowires are more likely to form a three-dimensional conductive network, which can enhance the anisotropy of the surface.

[0003] Among many one-dimensional materials, MnO2 nanowires are simple to prepare, and both themselves and their conversion products have certain wave-absorbing properties, which can be used as templates to prepare multi-shell hybrid nanofiber wave-absorbing agents. For example, the MnO2 / GNs composite wave-absorbing agent with "urchin" structure provided in Chinese Patent Application CN114702074S. The graphene-coated MnO2 composite wave-absorbing agent provided in Chinese Patent Application CN110642296A tightly combines the two groups in a chemical bond manner, which not only exhibits the dielectric loss performance of manganese dioxide on incident electromagnetic waves, but also combines the multiple scattering performance of reduced graphene on incident electromagnetic waves.

[0004] Based on the current research background, the present application provides a new composite wave-absorbing material. SUMMARY

[0005] The research team of the present application previously applied for an invention patent with the title "A hydrogenated graphdiyne sandwiched core-shell structure one-dimensional wave-absorbing agent and a preparation method thereof", application number 202310809479.2, which uses MnO2 nanowires as a template, sequentially coats hydrogenated graphdiyne (HsGDY) and polydopamine (PDA) on the surface to obtain MnO2@HsGDY@PDA nanowires, and after high-temperature calcination, MnO2 is reduced to MnO and PDA is converted to NC, thereby preparing the hydrogenated graphdiyne sandwiched core-shell structure nanowire MnO@HsGDY@NC. Although the wave-absorbing performance of the product as a wave-absorbing agent has been optimized compared to existing composite wave-absorbing materials, in order to reduce the material density while considering its loss capacity and impedance matching performance, and to enrich the types of wave-absorbing agents, the application team has further optimized the technology and provided a sleeve-shaped nanofiber containing hydrogenated graphdiyne and a preparation method thereof.

[0006] The inventive concept is as follows:

[0007] In view of the problems existing in the prior art composite wave-absorbing material, the research team of the present application optimizes the components and designs the structure to regulate the dielectric parameters and optimize the absorption performance, selects MnO2 nanowires which have certain wave-absorbing performance and their conversion products as templates, introduces hydrogenated graphdiyne and polydopamine into the templates for optimization, and designs a new one-dimensional wave-absorbing agent. Here, the new application of hydrogenated graphdiyne discovered by the research team is fully utilized, that is, it can be used to prepare a wave-absorbing agent. The hydrogenated graphdiyne is modified by introducing hydrogen atoms into the benzene ring to form a perfect pi-type conjugated system (a conjugated system formed by four types of carbon-carbon bonds), has a high specific surface area, a wide interplanar spacing, a high crystallinity, a uniform pore configuration, a controllable electronic structure and semiconductor properties, good electrical conductivity and a large number of active sites, contains a large number of alkyne bonds, and has a unique layered porous structure, which can provide a path for electron transmission and effectively enhance the dielectric loss of the material, and belongs to a functional component. Therefore, in order to further optimize the research and development results, the present application is intended to follow the design principles of "light quality, thin thickness, wide frequency band and strong absorption", remove the inorganic template, reduce the density, form a hollow structure, and create multiple reflections and scattering to ensure that the wave-absorbing performance of the magnesium oxide is maintained after the magnesium oxide is removed.

[0008] Based on the above inventive concept, in order to achieve the above object, the technical solution provided by the present application is as follows:

[0009] A sleeve-shaped nanofiber containing hydrogenated graphdiyne HsGDY@NC, which is characterized in that: the whole is a double-layer sleeve structure, the inner layer is a hydrogenated graphdiyne (HsGDY) layer, the outer layer is a nitrogen-doped carbon (NC) layer, the inner diameter is 10-40nm, the outer diameter is 60-110nm, and the length is 2.5-7μm.

[0010] The preparation method of the above-mentioned sleeve-shaped nanofiber containing hydrogenated graphdiyne HsGDY@NC, which is characterized in that, comprises the following steps:

[0011] 1) MnO2 nanowires are added to a mixed solution of solvent I and solvent II, and ultrasonic dispersion is performed to obtain a black suspension A;

[0012] The solvent I is tetrahydrofuran or pyridine;

[0013] The solvent II is trimethylamine or triethylamine;

[0014] 2) Under the protection of inert gas, 1,3,5-triethynylbenzene, catalyst I and catalyst II are added to the suspension A obtained in step 1), and stirring is performed at room temperature. After the reaction is completed, centrifugal separation, washing and freeze-drying are performed to obtain MnO2@HsGDY nanowires;

[0015] The catalyst I is a palladium catalyst in the form of a complex;

[0016] The catalyst II is a cuprous halide catalyst;

[0017] 3) dispersing the MnO2@HsGDY nanowire obtained in step 2) in a buffer solution with pH = 8.3-8.7 to obtain a suspension B, and then adding a buffer solution with pH = 8.3-8.7 and dissolved with dopamine hydrochloride into the suspension B, and reacting at room temperature under stirring, and then centrifuging, washing, and freeze-drying to obtain MnO2@HsGDY@PDA nanowire;

[0018] 4) dissolving the MnO2@HsGDY@PDA nanowire obtained in step 3) and oxalic acid in deionized water, and heating to react, and then centrifuging and washing with deionized water to obtain HsGDY@PDA nanotube;

[0019] 5) carbonizing the HsGDY@PDA nanotube obtained in step 4) under inert gas protection to obtain a sleeve-shaped nanofiber HsGDY@NC containing hydrogenated graphdiyne.

[0020] Further, in step 1), the diameter of the MnO2 nanowire is 20-40 nm, and the length is 4-7 μm.

[0021] The volume ratio of the solvent I and the solvent II is 1:1-3, and the mass concentration of the MnO2 nanowire in the suspension A is 1-3 mg / mL.

[0022] Further, in step 2), the catalyst I is bis(triphenylphosphine)palladium dichloride or tetrakis(triphenylphosphine)palladium;

[0023] The catalyst II is cuprous iodide, cuprous bromide, or cuprous chloride;

[0024] The molar ratio of 1,3,5-triethynylbenzene, the catalyst I, and the catalyst II is 3:1:1.

[0025] The mass ratio of 1,3,5-triethynylbenzene to the MnO2 nanowire is 1:10-15.

[0026] Reacting at room temperature under magnetic stirring for 48-72 h.

[0027] Further, in step 3), the buffer solution is a Tris hydrochloride buffer solution with pH = 8.3-8.7; the mass concentration of dopamine hydrochloride is 1-3 mg / mL; the mass concentration of the MnO2@HsGDY nanowire in the suspension B is 1-4 mg / mL; and the mass ratio of the MnO2@HsGDY nanowire to dopamine hydrochloride is 1:0.25-3.

[0028] Reacting at room temperature under magnetic stirring for 18-24 h.

[0029] Further, in step 4), the mass ratio of MnO2@HsGDY@PDA nanowires and oxalic acid is 1:60-90, and after adding deionized water, the mass concentration of MnO2@HsGDY@PDA nanowires is 1-3 mg / mL.

[0030] The reaction temperature is 75-85℃, and the reaction time is 20-24h.

[0031] Further, step 5) is specifically:

[0032] Under the protection of inert gas, the HsGDY@PDA nanotube obtained in step 4) is placed in a tube furnace for carbonization treatment at 600-900℃ for 1-3h, and the control rate of temperature rise is 1-5℃ / min (if the rate of temperature rise is too fast, the structure of the product will be damaged, defects will be formed, and the performance will be affected, and if the rate of temperature rise is too slow, the production efficiency will be affected), to obtain the sleeve-shaped nanofiber HsGDY@NC containing hydrogenated graphdiyne.

[0033] Further, the inert gas is nitrogen or argon.

[0034] Meanwhile, the application also provides the application of the sleeve-shaped nanofiber HsGDY@NC containing hydrogenated graphdiyne as a wave absorber.

[0035] And a one-dimensional wave absorber, which is characterized in that: it uses the sleeve-shaped nanofiber HsGDY@NC containing hydrogenated graphdiyne as a wave absorber for filling.

[0036] The advantages of the application are:

[0037] 1.The present application uses MnO2 nanowires as templates, Glaser coupling reaction of 1, 3, 5-triethynylbenzene and oxidative self-polymerization of dopamine (DA) in weak alkaline solution to uniformly coat hydrogenated graphdiyne (HsGDY) and polydopamine (PDA) on the surface of MnO2 nanowires in turn, then remove the hard template MnO2 nanowires by oxalic acid etching, and finally obtain HsGDY@NC nanotubes by high-temperature calcination. The material presents a double-layer hollow structure (i.e. hollow structure), the inner layer is a hydrogenated graphdiyne layer, the outer layer is a nitrogen-doped carbon layer (NC), the inner diameter is 10-40 nm, the outer diameter is 60-110 nm, the length is 2.5-7 μm, and the material has a large aspect ratio, a high specific surface area and good electrical conductivity. The composite wave-absorbing material introduces hydrogenated graphdiyne (HsGDY), which is conducive to enhancing the electrical conductivity loss of the material; the hollow structure is not only conducive to reducing the density of the material, but also conducive to the multiple reflection and scattering of electromagnetic waves, thereby enhancing the loss; the N-doping in the carbon material promotes the generation of dipole polarization; effective synergy, broadening the effective absorption bandwidth of the material, realizing the controllable preparation of a new type of one-dimensional wave-absorbing material with the characteristics of "light, thin, wide and strong".

[0038] 2.The method realizes the simple synthesis of the hollow sleeve-shaped fiber, the structure parameters of the target product can be effectively controlled by changing the amount of 1, 3, 5-triethynylbenzene, the amount of dopamine hydrochloride, the reaction time, etc., which enriches the types of one-dimensional materials and carbon materials, expands the application field of HsGDY, and has potential application value in the fields of electromagnetic pollution prevention and control, photocatalysis, energy conversion and storage, etc. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 is the SEM and TEM photos of the sleeve-shaped nanofiber containing hydrogenated graphdiyne;

[0040] Figure 2 is the adsorption-desorption isotherm of the sleeve-shaped nanofiber containing hydrogenated graphdiyne (BET specific surface area: 59.17 m 2 / g);

[0041] Figure 3 is the pore size distribution curve of the sleeve-shaped nanofiber containing hydrogenated graphdiyne (average pore size: 33.24 nm; pore volume: 0.19 cm 3 / g);

[0042] Figure 4 is the two-dimensional reflection loss image of the sleeve-shaped nanofiber containing hydrogenated graphdiyne. DETAILED DESCRIPTION

[0043] The content of the present application is further described in detail below in combination with the drawings and specific examples:

[0044] A preparation method of a sheath-like nanofiber HsGDY@NC containing hydrogenated graphdiyne, comprising the following steps:

[0045] 1) adding MnO2 nanowires into a mixed solution of solvent I and solvent II to obtain a black suspension A through ultrasonic dispersion;

[0046] The diameter of the MnO2 nanowires is 20-40 nm, and the length is 4-7 μm;

[0047] The solvent I is tetrahydrofuran or pyridine;

[0048] The solvent II is trimethylamine or triethylamine;

[0049] The volume ratio of the solvent I to the solvent II is 1:1-3, and the mass concentration of the MnO2 nanowires in the suspension A is 1-3 mg / mL;

[0050] 2) under the protection of inert gas, adding 1,3,5-triethynylbenzene, catalyst I and catalyst II into the suspension A obtained in step 1), and reacting at room temperature under magnetic stirring for 48-72 h, and then centrifuging, washing, and freeze-drying to obtain MnO2@HsGDY nanowires;

[0051] The catalyst I is bis-triphenylphosphine palladium dichloride or tetrakis(triphenylphosphine)palladium;

[0052] The catalyst II is cuprous iodide, cuprous bromide or cuprous chloride;

[0053] The molar ratio of the 1,3,5-triethynylbenzene, the catalyst I and the catalyst II is 3:1:1;

[0054] The mass ratio of the 1,3,5-triethynylbenzene to the MnO2 nanowires is 1:10-15;

[0055] 3) ultrasonically dispersing the MnO2@HsGDY nanowires obtained in step 2) in a buffer solution with pH=8.3-8.7 to obtain a suspension B, adding a buffer solution with hydrochloric acid dopamine dissolved therein with pH=8.3-8.7 into the suspension B, and reacting at room temperature under magnetic stirring for 18-24 h, and then centrifuging, washing with deionized water, and freeze-drying to obtain MnO2@HsGDY@PDA nanowires;

[0056] The buffer solution is a Tris hydrochloric acid buffer solution, and the mass concentration of the hydrochloric acid dopamine is 1-3 mg / mL;

[0057] In the suspension B, the mass concentration of the MnO2@HsGDY nanowires is 1-4 mg / mL, and the mass ratio of the MnO2@HsGDY nanowires to the hydrochloric acid dopamine is 1:0.25-3;

[0058] 4) MnO2@HsGDY@PDA nanowires obtained in step 3) and oxalic acid are added into deionized water to dissolve, and reacted at 75-85°C for 20-24h. After the reaction is completed, centrifugal separation is performed and deionized water is used for washing to obtain HsGDY@PDA nanotubes;

[0059] The mass ratio of MnO2@HsGDY@PDA nanowires and oxalic acid is 1:60-90, and after the addition of deionized water, the mass concentration of MnO2@HsGDY@PDA nanowires is 1-3mg / mL;

[0060] 5) HsGDY@PDA nanotubes obtained in step 4) are placed in a tube furnace for carbonization treatment at 600-900°C for 1-3h under the protection of inert gas, and the heating rate is controlled to be 1-5°C / min to obtain sleeve-shaped nanofibers HsGDY@NC containing hydrogenated graphdiyne.

[0061] The inert gas involved above is nitrogen or argon.

[0062] The following are specific examples:

[0063] Example 1

[0064] 100mg of MnO2 nanowires are added into a mixed solution of 40mL of tetrahydrofuran and 40mL of trimethylamine to obtain a black suspension A. Under the protection of inert gas, 10mg of 1,3,5-triethynylbenzene, 15.6mg of dichlorobis(triphenylphosphine)palladium and 3.2mg of cuprous bromide are added into the black suspension A, and the reaction is performed at room temperature for 70h under magnetic stirring. Centrifugal separation is performed and deionized water is used for washing and freeze-drying to obtain MnO2@HsGDY nanowires. 100mg of MnO2@HsGDY nanowires are dispersed in 80mL of Tris hydrochloride buffer solution with pH=8.3 to obtain a suspension B, and 40mL of Tris hydrochloride buffer solution with pH=8.3 and dissolved with 60mg of dopamine hydrochloride is added into the suspension B. The reaction is performed at room temperature for 20h under magnetic stirring. Centrifugal separation is performed and deionized water is used for washing and freeze-drying to obtain MnO2@HsGDY@PDA nanowires. 100mg of MnO2@HsGDY@PDA nanowires and 7g of oxalic acid are weighed and added into 100mL of deionized water to dissolve. The reaction is performed at 75°C for 20h. Centrifugal separation is performed and deionized water is used for washing to obtain HsGDY@PDA nanotubes. Under the protection of inert gas, the HsGDY@PDA nanotubes are carbonized in a tube furnace at 600°C for 1h, and the heating rate is controlled to be 3°C / min to obtain the product HsGDY@NC sleeve-shaped nanofibers.

[0065] From Figure 1The SEM and TEM photos show that the target product has a double-layer sleeve structure as a whole, with a hollow in the middle, a hydrogenated graphdiyne layer as the inner layer, and a nitrogen-doped carbon layer as the outer layer. The inner diameter is 10-40 nm, the outer diameter is 60-110 nm, and they are interwoven to form a three-dimensional network structure.

[0066] From Figure 2 the adsorption-desorption isotherm and Figure 3 the pore size distribution curve, it can be seen that the BET surface area is 59.17 m 2 / g, the average pore size is 33.24 nm, and the pore volume is 0.19 cm 3 / g.

[0067] Example 2

[0068] 80 mg of MnO2 nanowires were added to a mixed solution of 20 mL of tetrahydrofuran and 40 mL of triethylamine, and ultrasonic dispersion was performed to obtain a black suspension A. Under inert gas protection, 7.5 mg of 1,3,5-triethynylbenzene, 11.7 mg of bis-triphenylphosphine palladium dichloride, and 3.2 mg of cuprous iodide were added to the black suspension A, and the reaction was carried out at room temperature for 72 h under magnetic stirring. Centrifugation and washing with deionized water and freeze-drying were performed to obtain MnO2@HsGDY nanowires. 80 mg of MnO2@HsGDY nanowires were dispersed in 40 mL of Tris hydrochloride buffer solution with pH = 8.7 to obtain a suspension B, and 20 mL of Tris hydrochloride buffer solution with pH = 8.3 and dissolved with 30 mg of dopamine hydrochloride was added thereto. The reaction was carried out at room temperature for 24 h under magnetic stirring. Centrifugation and washing with deionized water and freeze-drying were performed to obtain MnO2@HsGDY@PDA nanowires. 100 mg of MnO2@HsGDY@PDA nanowires and 9 g of oxalic acid were weighed and dissolved in 50 mL of deionized water, and the reaction was carried out at 80°C for 22 h. Centrifugation and washing with deionized water were performed to obtain HsGDY@PDA nanotubes. Under inert gas protection, the HsGDY@PDA nanotubes were carbonized in a tube furnace at 650°C for 3 h, and the heating rate was controlled at 1°C / min to obtain the product HsGDY@NC sleeve-shaped nanofibers.

[0069] Example 3

[0070] MnO2nanowires (120 mg) were added into a mixed solution of pyridine (50 mL) and triethylamine (50 mL) to obtain a black suspension A. Under inert gas protection, 1,3,5-triethynylbenzene (10 mg), tetrakis(triphenylphosphine)palladium (25.6 mg) and cuprous bromide (3.2 mg) were added into the black suspension A, and the mixture was stirred at room temperature for 72 h. The product was obtained by centrifugation, washing with deionized water and freeze-drying. The obtained MnO2@HsGDY nanowires (100 mg) were dispersed in 100 mL of Tris-HCl buffer solution (pH = 8.3) to obtain a suspension B. Then, 80 mL of Tris-HCl buffer solution (pH = 8.3) containing dopamine hydrochloride (80 mg) was added into the suspension B, and the mixture was stirred at room temperature for 23 h. The product was obtained by centrifugation, washing with deionized water and freeze-drying. The obtained MnO2@HsGDY@PDA nanowires (150 mg) and oxalic acid (11 g) were dissolved in 100 mL of deionized water, and the mixture was stirred at 85 °C for 22 h. The product was obtained by centrifugation and washing with deionized water. The obtained HsGDY@PDA nanotubes were carbonized at 800 °C for 3 h in a tube furnace under inert gas protection, and the heating rate was controlled at 3 °C / min. The product HsGDY@NC sleeve-shaped nanofibers was obtained.

[0071] Example 4

[0072] MnO2nanowires (120 mg) were added into a mixed solution of pyridine (50 mL) and triethylamine (50 mL) to obtain a black suspension A. Under inert gas protection, 1,3,5-triethynylbenzene (10 mg), tetrakis(triphenylphosphine)palladium (25.6 mg) and cuprous bromide (3.2 mg) were added into the black suspension A, and the mixture was stirred at room temperature for 72 h. The product was obtained by centrifugation, washing with deionized water and freeze-drying. The obtained MnO2@HsGDY nanowires (100 mg) were dispersed in 100 mL of Tris-HCl buffer solution (pH = 8.3) to obtain a suspension B. Then, 80 mL of Tris-HCl buffer solution (pH = 8.3) containing dopamine hydrochloride (80 mg) was added into the suspension B, and the mixture was stirred at room temperature for 23 h. The product was obtained by centrifugation, washing with deionized water and freeze-drying. The obtained MnO2@HsGDY@PDA nanowires (150 mg) and oxalic acid (11 g) were dissolved in 100 mL of deionized water, and the mixture was stirred at 85 °C for 22 h. The product was obtained by centrifugation and washing with deionized water. The obtained HsGDY@PDA nanotubes were carbonized at 800 °C for 3 h in a tube furnace under inert gas protection, and the heating rate was controlled at 3 °C / min. The product HsGDY@NC sleeve-shaped nanofibers was obtained.

[0073] Example 5

[0074] MnO2nanowires (120 mg) were added into a mixed solution of tetrahydrofuran (30 mL) and trimethylamine (60 mL) to obtain a black suspension A. Under inert gas protection, 1,3,5-triethynylbenzene (10 mg), tetrakis(triphenylphosphine)palladium (25.6 mg) and cuprous chloride (2.2 mg) were added into the black suspension A, and the mixture was stirred at room temperature for 60 h. The product was obtained by centrifugation, washing with deionized water and freeze-drying. The product (100 mg) was dispersed in a Tris hydrochloride buffer solution (pH = 8.5, 50 mL) to obtain a suspension B. A Tris hydrochloride buffer solution (pH = 8.5, 80 mL) containing dopamine hydrochloride (120 mg) was added into the suspension B, and the mixture was stirred at room temperature for 22 h. The product was obtained by centrifugation, washing with deionized water and freeze-drying. The product (100 mg) and oxalic acid (7.5 g) were dissolved in deionized water (70 mL), and the mixture was stirred at 80 °C for 20 h. The product was obtained by centrifugation and washing with deionized water. The product was carbonized at 700 °C for 2 h in a tube furnace under inert gas protection, and the heating rate was controlled at 5 °C / min. The product HsGDY@NC sleeve-shaped nanofiber was obtained.

[0075] Example 6

[0076] MnO2nanowires (200 mg) were added into a mixed solution of tetrahydrofuran (70 mL) and triethylamine (70 mL) to obtain a black suspension A. Under inert gas protection, 1,3,5-triethynylbenzene (20 mg), tetrakis(triphenylphosphine)palladium (51.3 mg) and cuprous iodide (8.4 mg) were added into the black suspension A, and the mixture was stirred at room temperature for 65 h. The product was obtained by centrifugation, washing with deionized water and freeze-drying. The product (100 mg) was dispersed in a Tris hydrochloride buffer solution (pH = 8.7, 80 mL) to obtain a suspension B. A Tris hydrochloride buffer solution (pH = 8.7, 100 mL) containing dopamine hydrochloride (200 mg) was added into the suspension B, and the mixture was stirred at room temperature for 22 h. The product was obtained by centrifugation, washing with deionized water and freeze-drying. The product (150 mg) and oxalic acid (12 g) were dissolved in deionized water (100 mL), and the mixture was stirred at 78 °C for 21 h. The product was obtained by centrifugation and washing with deionized water. The product was carbonized at 720 °C for 3 h in a tube furnace under inert gas protection, and the heating rate was controlled at 2 °C / min. The product HsGDY@NC sleeve-shaped nanofiber was obtained.

[0077] Example 7

[0078] The 20 mg of MnO2 nanowires were added to a mixed solution of 10 mL of tetrahydrofuran and 10 mL of triethylamine to obtain a black suspension A. Under inert gas protection, 2 mg of 1,3,5-triethynylbenzene, 5.1 mg of tetrakis(triphenylphosphine)palladium and 0.8 mg of cuprous iodide were added to the black suspension A, and the reaction was carried out at room temperature for 65 h under magnetic stirring. After centrifugation and washing with deionized water, freeze-drying was carried out to obtain MnO2@HsGDY nanowires. The 50 mg of MnO2@HsGDY nanowires were dispersed in 30 mL of Tris hydrochloride buffer solution with pH = 8.3 to obtain a suspension B, and 10 mL of Tris hydrochloride buffer solution with pH = 8.3 and 20 mg of dopamine hydrochloride were added to the suspension B, and the reaction was carried out at room temperature for 23 h under magnetic stirring. After centrifugation and washing with deionized water, freeze-drying was carried out to obtain MnO2@HsGDY@PDA nanowires. The 100 mg of MnO2@HsGDY@PDA nanowires and 7.7 g of oxalic acid were weighed and dissolved in 100 mL of deionized water, and the reaction was carried out at 75 ℃ for 20 h. After centrifugation and washing with deionized water, HsGDY@PDA nanotubes were obtained. Under inert gas protection, the HsGDY@PDA nanotubes were carbonized in a tube furnace at 700 ℃ for 2 h, and the temperature rising rate was controlled at 5 ℃ / min to obtain the product HsGDY@NC sleeve-shaped nanofibers.

[0079] In addition, the wave absorption performance of the target product was detected, and the results are shown in Table 1. Figure 4 As shown in the reflection loss image, the minimum reflection loss of the target product is -59.48 dB, the effective absorption bandwidth is 5.4 GHz, and the filler amount is 7%. It can be seen that, on the basis of the prior technical scheme, the inorganic template is removed to form a hollow structure, which not only reduces the material density and the filler amount compared with the prior scheme (the minimum reflection loss is -60.82 dB, the effective absorption bandwidth is 7.2 GHz, and the filler amount is 8%), but also maintains the wave absorption performance of the composite material at an equivalent level, enriches the types of wave absorbing agents, has good application prospect and competitiveness, and can be used as a wave absorbing filler to prepare devices with radar stealth function.

[0080] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the present application, and these modifications or replacements shall be covered within the protection scope of the present application.

Claims

1. A method for preparing a sheath-like nanofiber HsGDY@NC containing hydrogenated graphdiyne, characterized in that, The method comprises the following steps: 1) uniformly dispersing MnO2 nanowires into a mixed solution of solvent I and solvent II to obtain a suspension A; the solvent I is tetrahydrofuran or pyridine; the solvent II is trimethylamine or triethylamine; 2) under the protection of nitrogen or argon, adding 1,3,5-triethynylbenzene, catalyst I and catalyst II into the suspension A obtained in step 1), and reacting at room temperature under stirring, and then centrifuging, cleaning and freeze-drying to obtain MnO2@HsGDY nanowires; the catalyst I is a palladium catalyst in the form of a complex; the catalyst II is a cuprous halide catalyst; 3) dispersing the MnO2@HsGDY nanowires obtained in step 2) into a buffer solution with pH=8.3-8.7 to obtain a suspension B, adding a buffer solution with pH=8.3-8.7 and dissolved with hydrochloric acid dopamine into the suspension B, and reacting at room temperature under stirring, and then centrifuging, cleaning and freeze-drying to obtain MnO2@HsGDY@PDA nanowires; 4) adding MnO2@HsGDY@PDA nanowires and oxalic acid into deionized water to dissolve and heat to react, and then centrifuging and cleaning to obtain HsGDY@PDA nanotubes; 5) under the protection of nitrogen or argon, carbonizing the HsGDY@PDA nanotubes obtained in step 4) to obtain a sleeve-shaped nanofiber HsGDY@NC containing hydrogenated graphdiyne.

2. The method according to claim 1, wherein: in step 1), the diameter of the MnO2 nanowires is 20-40 nm, and the length is 4-7 μm; the volume ratio of the solvent I to the solvent II is 1:1-3, and the mass concentration of the MnO2 nanowires in the suspension A is 1-3 mg / mL.

3. The method according to claim 2, wherein: in step 2), the catalyst I is bis(triphenylphosphine)palladium dichloride or tetrakis(triphenylphosphine)palladium; the catalyst II is cuprous iodide, cuprous bromide or cuprous chloride; the molar ratio of 1,3,5-triethynylbenzene, catalyst I and catalyst II is 3:1:1; the mass ratio of 1,3,5-triethynylbenzene to the MnO2 nanowires is 1:10-15; the reaction is carried out at room temperature under magnetic stirring for 48-72 h.

4. The method according to claim 3, wherein: in step 3), the buffer solution is a Tris hydrochloride buffer solution with pH=8.3-8.7; the mass concentration of the hydrochloric acid dopamine is 1-3 mg / mL; the mass concentration of the MnO2@HsGDY nanowires in the suspension B is 1-4 mg / mL; the mass ratio of the MnO2@HsGDY nanowires to the hydrochloric acid dopamine is 1:0.25-3; the reaction is carried out at room temperature under magnetic stirring for 18-24 h.

5. The method according to claim 4, wherein: in step 4), the mass ratio of the MnO2@HsGDY@PDA nanowires to oxalic acid is 1:60-90, and after adding deionized water, the mass concentration of the MnO2@HsGDY@PDA nanowires is 1-3 mg / mL. The reaction temperature is 75-85 ℃, and the reaction time is 20-24 h.

6. The preparation method according to claim 5, characterized in that, Step 5) is specifically: Under the protection of nitrogen or argon, the HsGDY@PDA nanotube obtained in step 4) is carbonized in a tube furnace at 600-900 ℃ for 1-3 h, and the temperature rising rate is controlled to be 1-5 ℃ / min, to obtain the sleeve-shaped nanofiber HsGDY@NC containing hydrogenated graphdiyne.

7. A sheath-like nanofiber HsGDY@NC containing hydrogenated graphdiyne, characterized in that: The sleeve-shaped nanofiber HsGDY@NC containing hydrogenated graphdiyne is prepared by the preparation method in any one of claims 1-6; has a double-layer sleeve structure as a whole, the inner layer is a hydrogenated graphdiyne layer, the outer layer is a nitrogen-doped carbon layer, the inner diameter is 10-40 nm, the outer diameter is 60-110 nm, and the length is 2.5-7 μm.

8. Application of the sleeve-shaped nanofiber HsGDY@NC containing hydrogenated graphdiyne in claim 7 as a wave absorber.

9. A device having a radar stealth function, characterized by: The sleeve-shaped nanofiber HsGDY@NC containing hydrogenated graphdiyne in claim 7 is used as a wave absorber for filling.

Images