An amorphous carbon-based material with quasi-continuous sp 2 domains, method of preparation and use

Abstract

The application discloses an amorphous carbon-based material with quasi-continuous sp 2 domains, which is prepared by a metal salt-assisted bubble method to induce carbon atoms to rearrange under the curvature of a nano-bubble interface, successfully constructing short-range ordered quasi-continuous sp 2 domains around nanopores, and having long-range electronic transmission channels and rich conjugated / non-conjugated heterogeneous interfaces, which can synergistically enhance conductive loss and interface polarization loss. The method can anchor single-atom metals on the carbon-based body and form M-Nx structures by selecting appropriate metal precursors, and provide strong dipole polarization. The material can effectively absorb an effective absorption bandwidth of 8.0 GHz under a low filling amount of 7 wt%, and the preparation method has strong universality and is suitable for various metals and carbon precursors, thereby providing a new strategy for light-weight wide-band electromagnetic wave absorbing materials.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic wave absorbing materials technology, specifically to a material with quasi-continuous sp... 2 Amorphous carbon-based materials in the field, their preparation methods and applications. Background Technology

[0002] With the widespread adoption of 5G mobile communications, radar detection, and smart electronic devices, electromagnetic radiation pollution has become an increasingly serious problem, not only interfering with the reliability of electronic devices but also potentially having negative impacts on human health. Developing efficient, lightweight, and broadband electromagnetic wave absorbing materials has become an urgent need.

[0003] Carbon-based materials, especially amorphous carbon, have attracted much attention due to their low density, good chemical stability, and tunable dielectric properties. Amorphous carbon contains sp... 2 Conductive micro-regions composed of hybrid states (called sp) 2 domain) and sp 3 The non-conjugated regions formed by hybrid states create numerous heterogeneous interfaces, which can lead to interfacial polarization losses. However, sp in traditional amorphous carbon... 2 The domains are discretely distributed, and electrons mainly rely on hopping conduction. The low conductivity results in insufficient dielectric loss under low filling amount, making it difficult to achieve lightweight microwave absorption.

[0004] In recent years, researchers have attempted to improve the microwave absorption performance of carbon materials by controlling their atomic-level structure. For example, Chinese patent document CN106944119B discloses a method using carbon nitride as a carrier, employing a complexation of metal precursors and carbon-nitrogen precursors. This method suppresses metal atom aggregation through the interaction between the metal center and ligands, and prepares carbon nitride-supported single-atom metal catalytic materials via one-step pyrolysis. This achieves the loading of metal in a zero-valence single-atom dispersed form on the surface of layered graphitic carbon nitride. Another example is Chinese patent document CN119570444A, which discloses single-atom modified carbon composite microwave absorbing materials and their preparation. The method uses pyrrole monomer and hydrogenated molybdenum trioxide as raw materials to anchor metalloporphyrin on the surface of polypyrrole through click reaction. The carbon composite microwave absorbing material with single metal sites (sM(N4)@NC, M=Ni, Co, Cu, etc.) on the nitrogen-doped carbon layer is prepared by high-temperature pyrolysis. This technology overcomes the bottleneck of easy aggregation of metal atoms at high temperature in traditional electromagnetic wave absorbing materials, and realizes atomic-level dispersion and precise control of single metal sites. The dipole polarization loss induced by the metal-nitrogen coordination structure is used as the dominant mechanism, and the minimum reflection loss reaches -51.7 dB with an effective absorption bandwidth of 6.44 GHz.

[0005] However, these existing technologies mainly introduce single-atom sites into carbon matrices that already possess intrinsically conductive network structures (such as graphene or MOF-derived carbon) through doping strategies. The conductive network structure of the carbon matrix itself is already formed during the initial preparation process, and they do not involve constructing quasi-continuous sp atoms by inducing carbon atom rearrangement through metal salt-assisted bubble methods. 2 The design concept of the domain. If a quasi-continuous sp... 2 A network that provides both fast electron transport channels and retains abundant conjugated / non-conjugated interfaces is expected to synergistically enhance conductivity and interfacial polarization losses. Furthermore, introducing single-atom metals into a carbon matrix can form strongly polar M-Nx sites, further providing dipole polarization without significantly deteriorating impedance matching. However, simultaneously achieving quasi-continuous sp... 2 The construction of domains and the uniform dispersion of single-atom metals still face enormous challenges. Summary of the Invention

[0006] To solve the above-mentioned technical problems, the present invention provides a quasi-continuous sp 2 Amorphous carbon-based materials in the domain form short-range ordered quasi-continuous sps around nanopores. 2 This domain enhances the effective absorption bandwidth of the material.

[0007] A quasi-continuous sp 2 Amorphous carbon-based materials in the domain, wherein the amorphous carbon-based materials are porous nanosheets containing nanopores, and quasi-continuous sps formed around the nanopores are composed of short-range ordered graphitized carbon walls. 2 The domain, and the quasi-continuous sp 2 The domains are interconnected to form electron transport channels; the amorphous carbon-based material as a whole maintains a long-range disordered amorphous structure.

[0008] In this invention, carbon precursors generate bubbles during decomposition, thereby forming pores within amorphous carbon-based materials. A metal salt-assisted bubble-forming method is used to induce carbon atoms to rearrange under the curvature of the nanobubble interface, successfully constructing short-range ordered quasi-continuous spp around the nanopores. 2 This structure combines long-range electron transport channels with abundant conjugated / non-conjugated heterojunctions, synergistically enhancing conductivity loss and interfacial polarization loss. The present invention features quasi-continuous sp... 2 Amorphous carbon-based materials in the domain can still achieve high effective absorption bandwidth even with low filling amounts, significantly outperforming traditional discrete sp... 2 Amorphous carbon-based materials in the domain.

[0009] Preferably, the quasi-continuous sp 2 The domain induces carbon atoms to rearrange their orientation under the curvature of the nanobubble interface during pyrolysis through a metal salt-assisted bubble method.

[0010] The present invention also provides the above-described quasi-continuous sp 2 A method for preparing amorphous carbon-based materials in the domain includes the following steps: (1) The carbon precursor and the metal salt template are mixed evenly in a solvent to obtain a mixture; (2) Freeze-dry the mixture obtained in step (1) to obtain precursor powder; (3) Under an inert atmosphere, the precursor powder obtained in step (2) is heated to the pyrolysis temperature and held at that temperature to melt, foam, and carbonize the carbon precursor. Then, the metal salt template is removed, and after drying, a quasi-continuous sp... 2 Amorphous carbon-based materials in the domain.

[0011] Preferably, in step (1), the carbon precursor is chitosan or rhodanine, both of which are nitrogen-containing carbon precursors.

[0012] Preferably, in step (1), the metal salt template is an alkali metal halide.

[0013] More preferably, the metal salt template is at least one of sodium chloride, potassium chloride, and lithium chloride.

[0014] More preferably, the carbon precursor is chitosan, and the metal salt template is sodium chloride.

[0015] Preferably, in step (1), the mass ratio of the carbon precursor to the metal salt template is 1:5~20.

[0016] Preferably, in step (3), the inert atmosphere is argon or nitrogen.

[0017] Preferably, in step (3), the pyrolysis temperature is 800~1200 ℃, the heating rate is 1~10 ℃ / min, and the holding time is 1~5 h.

[0018] Preferably, in step (3), the method for removing the metal salt template is: washing with deionized water or dilute acid solution.

[0019] The present invention also provides an amorphous carbon-based electromagnetic wave absorbing material loaded with a single-atom metal, comprising the above-mentioned material having a quasi-continuous sp... 2 Amorphous carbon-based materials in the domain, and single-atom metals uniformly dispersed in the amorphous carbon-based materials, wherein the single-atom metals are in the form of MN x The coordination structure exists, where M is a metallic element and x is the number of nitrogen atoms in the coordination structure, selected from 2 to 8.

[0020] Preferably, the metallic element M is at least one of a transition metal or a metal from group 13 to 15.

[0021] More preferably, the metallic element M is at least one selected from Fe, Co, Ni, Cu, Zn, Mn, Cr, Mo, Ru, Pd, Pt, Ir, Al, Ga, and Y.

[0022] Preferably, in the amorphous carbon-based electromagnetic wave absorbing material, the loading of metal element M is 0.1~10wt%.

[0023] This invention also provides a method for preparing the above-mentioned amorphous carbon-based electromagnetic wave absorbing material loaded with a single-atom metal, comprising the following steps: S1. Dissolve the carbon precursor, the metal salt template, and the metal precursor in a solvent and mix them evenly to obtain a mixture; wherein, the metal precursor is a soluble metal salt containing the metal element M. S2. Freeze-dry the mixture obtained in step S1 to obtain precursor powder; S3. Under an inert atmosphere, the precursor powder obtained in step S2 is heated to the pyrolysis temperature and kept at that temperature. Then, the metal salt template is removed and dried to obtain an amorphous carbon-based electromagnetic wave absorbing material loaded with a single-atom metal.

[0024] Preferably, in step S1, the metal precursor is a nitrate containing the metal element M.

[0025] More preferably, the metal precursor is at least one selected from ferric nitrate, cobalt nitrate, nickel nitrate, copper nitrate, zinc nitrate, and yttrium nitrate.

[0026] Preferably, in step S1, the mass ratio of the carbon precursor, the metal salt template, and the metal precursor is 1:5~20:0.01~0.2.

[0027] Preferably, in step S3, the pyrolysis temperature is 800~1200 ℃.

[0028] The present invention also provides the above-described quasi-continuous sp 2 Application of amorphous carbon materials or amorphous carbon-based electromagnetic wave absorbing materials loaded with single-atom metals in the fabrication of electromagnetic wave absorbing devices.

[0029] Preferably, the electromagnetic wave absorbing device is at least one of stealth coating, electromagnetic shielding film, and wave absorbing structural component.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) In this invention, carbon atoms are rearranged under the curvature of the nanobubble interface by inducing the carbon atom rearrangement through the metal salt-assisted bubble method, and a quasi-continuous sp is successfully constructed. 2 Amorphous carbon materials in the domain, this structure combines long-range electron transport channels with abundant conjugated / non-conjugated heterojunction interfaces, which can synergistically enhance conductivity loss and interfacial polarization loss.

[0031] (2) The amorphous carbon material of the present invention can achieve an effective absorption bandwidth of 7.1 GHz with a low filling amount of only 7 wt%, which is significantly better than the traditional discrete sp 2 Amorphous carbon.

[0032] (3) This invention also enables the production of quasi-continuous sp... by selecting different metal precursors. 2 Uniform anchoring of single-atom metals on a carbon matrix to form highly polar MN x The dipole center provides fast-response dipole polarization while avoiding excessive disruption of the conductive network and maintaining good impedance matching.

[0033] (4) When the amorphous carbon-based electromagnetic wave absorbing material is combined with paraffin, the effective absorption bandwidth reaches 8.0 GHz with a carbon material filling amount of 7 wt%, and the thickness is only 3.0 mm, showing excellent broadband and lightweight wave absorption performance.

[0034] (5) The preparation method of the present invention is highly versatile and can be extended to various carbon precursors, various metal salt templates and various single-atom metals, making it easy to scale up production. Attached Figure Description

[0035] Figure 1 In Example 1, chitosan was used as a carbon precursor to prepare a quasi-continuous sp... 2 TEM image of the amorphous carbon material (i.e., C800) in the domain.

[0036] Figure 2 This is the selected area electron diffraction pattern of C800 in Example 1.

[0037] Figure 3 The reflection loss curve is shown for the absorbing material prepared by C800 in Example 1.

[0038] Figure 4 This is a TEM image of C1000 obtained by carbonization at 1000℃ in Example 2.

[0039] Figure 5 This is the selected area electron diffraction pattern of C1000 in Example 2.

[0040] Figure 6 This is a TEM image of C1200 obtained by carbonization at 1200℃ in Example 3.

[0041] Figure 7 This is the selected area electron diffraction pattern of C1200 in Example 3.

[0042] Figure 8 In Example 4, rhodanine was used as a carbon precursor to prepare a quasi-continuous sp... 2TEM image of the amorphous carbon material (i.e., R800) in the domain.

[0043] Figure 9 This is a spherical aberration electron microscope image of the amorphous carbon-based electromagnetic wave absorbing material (i.e., C800 / NFe) loaded with monatomic iron metal prepared in Example 5.

[0044] Figure 10 This is a TEM image of C800 / NFe prepared in Example 5.

[0045] Figure 11 This is a fitted image of the extended X-ray absorption fine structure spectrum (EXAFS) in R space for C800 / NFe prepared in Example 5.

[0046] Figure 12 The reflection loss curve is shown for the C800 / NFe absorbing material prepared in Example 5.

[0047] Figure 13 This is a TEM image of the amorphous carbon-based electromagnetic wave absorbing material (i.e., C800 / NY) loaded with single-atom yttrium metal prepared in Example 6.

[0048] Figure 14 This is a high-magnification TEM image of the C800 / NY in Example 6.

[0049] Figure 15 This is an element mapping diagram of C800 / NY in Example 6.

[0050] Figure 16 For the discrete sp prepared in Comparative Example 1 2 TEM image of the amorphous carbon material (i.e., S800) in the domain.

[0051] Figure 17 This is a TEM image of the C600 material obtained by carbonization at 600℃ in Comparative Example 2.

[0052] Figure 18 The selected area electron diffraction pattern of C600 in Comparative Example 2 is shown.

[0053] Figure 19 This is a TEM image of the amorphous carbon-based electromagnetic wave absorbing material (i.e., C800 / CFe) loaded with Fe nanoparticles prepared in Comparative Example 3.

[0054] Figure 20 The reflection loss curve is shown for the C800 / CFe absorbing material in Comparative Example 3.

[0055] Figure 21 This is a TEM image of the amorphous carbon-based electromagnetic wave absorbing material (i.e., C800 / NNi) loaded with metal nano-Ni particles prepared in Comparative Example 4. Detailed Implementation

[0056] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited to the following embodiments.

[0057] All raw materials used in this invention are commercially available.

[0058] Example 1: Preparation of quasi-continuous sp from chitosan as a carbon precursor 2 Amorphous carbon materials in the domain (i.e., C800) 3.0 g of chitosan and 3 mL of acetic acid were dissolved in 200 mL of deionized water and stirred for 2 h to obtain solution A. 40 g of sodium chloride was dissolved in 200 mL of deionized water to obtain solution B. Solution A and solution B were mixed and stirred for another 2 h. The mixture was frozen at -40℃ for 48 h, and then freeze-dried for 72 h to obtain precursor powder. The powder was placed in a tube furnace and heated to 800℃ at 2℃ / min under an argon atmosphere, held at that temperature for 2 h, and then allowed to cool naturally. The product was washed several times with deionized water to remove NaCl and dried at 60℃ to obtain C800.

[0059] Figure 1 This is a TEM image of the C800; the area enclosed by the dashed line represents the quasi-continuous spline. 2 domain.

[0060] Figure 2 The selected area electron diffraction pattern of C800 shows that the diffuse rings indicate that the carbon lattice of C800 has a long-range disordered structure, indicating that it is amorphous.

[0061] 7 wt% C800 was mixed with paraffin and pressed into a ring-shaped sample with a diameter of 7.0 mm and a height of 3.0 mm. Its electromagnetic parameters in the 2~18 GHz frequency band were then tested. Figure 3 The reflection curve of C800 shows that an effective absorption bandwidth of 7.1 GHz can be achieved with a thickness of 2.46 mm.

[0062] Example 2: The preparation method is the same as in Example 1, except that the pyrolysis temperature is increased to 1000 °C to obtain amorphous carbon material, namely C1000.

[0063] Figure 4 This is a TEM image of C1000, showing quasi-continuous sp around the stomata. 2 domain.

[0064] Figure 5 The selected area electron diffraction pattern of C1000, although it is also a diffuse halo, has a higher brightness than that of C800, indicating that the crystallinity has been improved.

[0065] Example 3: The preparation method is the same as in Example 1, except that the pyrolysis temperature is increased to 1200 °C to obtain amorphous carbon material, namely C1200.

[0066] Figure 6 This is a TEM image of C1200, showing quasi-continuous splines forming around the stomata. 2 domain.

[0067] Figure 7 The selected area electron diffraction pattern of C1200, although it is also a diffuse halo, has a higher brightness than C800 and C1000, indicating improved crystallinity.

[0068] Example 4 The preparation method is the same as in Example 1, except that chitosan is replaced with rhodanine to obtain a quasi-continuous sp. 2 Amorphous carbon materials in the domain (i.e., R800).

[0069] Figure 8 The TEM image of R800 shows quasi-continuous sp2 around the nanopores. 2 domain.

[0070] Example 5: Preparation of amorphous carbon-based electromagnetic wave absorbing material loaded with monatomic iron Based on Example 1, 1 mmol Fe(NO3)3·9H2O (dissolved in 20 mL of water) was added to the mixture as an iron precursor. The remaining steps were the same, and an amorphous carbon-based electromagnetic wave absorbing material loaded with monatomic iron, namely C800 / NFe, was obtained. The iron loading was found to be 2.2 wt% by ICP test.

[0071] Figure 9 The image shows a spherical aberration electron microscope image of C800 / NFe. The dashed area represents monatomic iron loaded on amorphous carbon material. Figure 10 The TEM image of C800 / NFe shows a quasi-continuous spline structure around the nanopores. 2 domain.

[0072] Figure 11 The fitting results of the extended X-ray absorption fine structure spectrum (EXAFS) of C800 / NFe in R space are used to derive Fe-N x The value of x in the equation is 4.

[0073] Figure 12 The reflection curve for C800 / NFe is shown in the reference diagram. Figure 2 The testing method revealed that with a low filler content of only 7 wt% and a thickness of 3 mm, an effective absorption bandwidth of 8.0 GHz can be achieved.

[0074] Example 6: Preparation of amorphous carbon-based electromagnetic wave absorbing material loaded with single-atom yttrium Based on Example 1, 1 mmol Y(NO3)3·6H2O (dissolved in 20 mL of water) was added to the mixture as an iron precursor. The remaining steps were the same to obtain an amorphous carbon-based electromagnetic wave absorbing material loaded with monatomic iron, namely C800 / NY.

[0075] Figure 13 The TEM image of the C800 / NY shows its porous morphology. Figure 14 This is a high-magnification TEM image of C800 / NY, which shows quasi-continuous sp2 around the nanopores. 2 domain. Figure 15 The elemental mapping diagram of C800 / NY shows that the Y element is uniformly dispersed without agglomeration, indicating that Y is loaded on the surface of amorphous carbon in the form of single atoms.

[0076] Comparative Example 1: With discrete sp 2 Preparation of amorphous carbon materials in the domain The preparation method is the same as in Example 1, except that NaCl was not added to the mixture. The other steps are the same, resulting in a product with discrete sp 2 Amorphous carbon materials in the domain, namely S800.

[0077] Figure 16 The TEM image of the S800 shows discrete spp particles. 2 domain.

[0078] Comparative Example 2 The preparation method is the same as in Example 1, except that the pyrolysis temperature is reduced to 600 °C to obtain amorphous carbon material, namely C600.

[0079] Figure 17 The TEM image of C600 shows obvious pores, but no quasi-continuous splines are formed around the pores. 2 domain. Figure 18 The selected area electron diffraction pattern of C600 shows a diffuse ring, with a brightness lower than that of C800, C1000, and C1200, indicating the worst crystallinity.

[0080] Comparative Example 3: Preparation of Control Sample C800 / CFe with Loaded Iron Nanoparticles In Example 5, Fe(NO3)3·9H2O was replaced with 1 mmol FeCl3·6H2O, while the rest remained the same, resulting in C800 / CFe.

[0081] Figure 19The image shows a TEM image of C800 / CFe. The black areas represent aggregated iron nanoparticles, making it impossible to prepare amorphous carbon-based electromagnetic wave absorbing materials loaded with single-atom iron. This is because nitrate ions (NO3-) cannot be used. - At relatively low temperatures (approximately 200–400 °C), chitosan decomposes into a gas, causing a rapid release of iron ions onto the carrier surface, before significant migration of these ions. These iron ions quickly bind to functional groups (such as -OH and -NH2) on chitosan, thus being "fixed" at the dispersion sites, which facilitates the formation of highly dispersed individual atoms. Meanwhile, chloride ions (Cl...) - Iron ions are relatively stable and do not easily release at low temperatures, making it difficult for them to bind with chitosan. This allows iron ions more time and energy to migrate and aggregate on the carrier, making it easier to form cluster structures or nanoparticles.

[0082] Figure 20 The reflection curve for C800 / CFe shows that, with a filler content of 7 wt%, the bandwidth is only 5.9 GHz.

[0083] Comparative Example 4: Preparation of Ni-supported nanoparticle control sample C800 / CNi In Example 5, Fe(NO3)3·9H2O was replaced with 1 mmol NiCl2·6H2O, while the rest remained the same, resulting in C800 / CNi.

[0084] Figure 21 The image shows a TEM image of C800 / CNi. The black areas in the image are agglomerated nickel nanoparticles, which makes it impossible to prepare amorphous carbon-based electromagnetic wave absorbing materials loaded with single-atom nickel.

[0085] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A quasi-continuous sp 2 Amorphous carbon-based materials in the domain, characterized in that, The amorphous carbon-based material is a porous nanosheet containing nanopores, around which quasi-continuous splines composed of short-range ordered graphitized carbon walls are formed. 2 The domain, and the quasi-continuous sp 2 The domains are interconnected to form electron transport channels; the amorphous carbon-based material as a whole maintains a long-range disordered amorphous structure.

2. The quasi-continuous sp as described in claim 1 2 A method for preparing amorphous carbon-based materials in the domain, characterized in that, Includes the following steps: (1) The carbon precursor and the metal salt template are mixed evenly in a solvent to obtain a mixture; (2) Freeze-dry the mixture obtained in step (1) to obtain precursor powder; (3) Under an inert atmosphere, the precursor powder obtained in step (2) is heated to the pyrolysis temperature and held at that temperature to melt, foam, and carbonize the carbon precursor. Then, the metal salt template is removed, and after drying, a quasi-continuous sp... 2 Amorphous carbon-based materials in the domain.

3. The quasi-continuous sp as described in claim 2 2 A method for preparing amorphous carbon-based materials in the domain, characterized in that, In step (1), the carbon precursor is chitosan or rhodanine.

4. The quasi-continuous sp as described in claim 2 2 The method for preparing amorphous carbon-based materials in the domain is characterized by In step (1), the metal salt template is an alkali metal halide.

5. The quasi-continuous sp as described in claim 2 2 A method for preparing amorphous carbon-based materials in the domain, characterized in that, In step (1), the mass ratio of the carbon precursor to the metal salt template is 1:5~20.

6. The quasi-continuous sp as described in claim 2 2 A method for preparing amorphous carbon-based materials in the domain, characterized in that, In step (3), the pyrolysis temperature is 800~1200 ℃, the heating rate is 1~10 ℃ / min, and the holding time is 1~5 h.

7. An amorphous carbon-based electromagnetic wave absorbing material loaded with a single-atom metal, characterized in that, Including the quasi-continuous sp as described in claim 1 2 Amorphous carbon-based materials in the domain, and single-atom metals uniformly dispersed in the amorphous carbon-based materials, wherein the single-atom metals are in the form of MN x The coordination structure exists, wherein M is a metallic element and x is the number of nitrogen atoms in the coordination structure, selected from 2 to 8; the metallic element M is at least one of a transition metal or a metal from group 13 to 15.

8. The method for preparing the amorphous carbon-based electromagnetic wave absorbing material loaded with a single-atom metal according to claim 7, characterized in that, Includes the following steps: S1. Dissolve the carbon precursor, the metal salt template, and the metal precursor in a solvent and mix them evenly to obtain a mixture; wherein, the metal precursor is a soluble metal salt containing the metal element M. S2. Freeze-dry the mixture obtained in step S1 to obtain precursor powder; S3. Under an inert atmosphere, the precursor powder obtained in step S2 is heated to the pyrolysis temperature and kept at that temperature. Then, the metal salt template is removed and dried to obtain an amorphous carbon-based electromagnetic wave absorbing material loaded with a single-atom metal.

9. The method for preparing the amorphous carbon-based electromagnetic wave absorbing material loaded with a single-atom metal according to claim 8, characterized in that, In step S1, the metal precursor is a nitrate containing the metal element M.

10. The quasi-continuous sp as described in claim 1 2 The application of amorphous carbon materials in the field or amorphous carbon-based electromagnetic wave absorbing materials loaded with monatomic metals as described in claim 7 in the preparation of electromagnetic wave absorbing devices.

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