Cu9s5 / cgfs electromagnetic wave absorbing material, preparation method and application

Abstract

The application discloses Cu9S5 / CGFS electromagnetic wave absorbing material, a preparation method and application, and the method steps for preparing the wave absorbing material are as follows: S1: adding coal gasification fine slag and CuCl2*2H2O into an ethanol aqueous solution in sequence to obtain a mixed solution A; S2: dissolving Na2S*9H2O in the ethanol aqueous solution to obtain a mixed solution B; S3: mixing and reacting the mixed solution A of S1 and the mixed solution B of S2, and drying the product after the reaction to obtain a Cu9S5 / CGFS composite material. The application takes component synergy and interface engineering as a guiding strategy, optimizes the poor impedance matching defect of CGFS as a single component, forms Cu9S5-Cu9S5 and Cu9S5-CGFS phase interfaces, introduces interface polarization-dipole polarization, and enhances the attenuation capacity of the composite material, which has important significance for limiting the excessively high conductivity of CGFS, enriching multiple polarization loss, and guaranteeing the sustainable development of green energy.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, and in particular to Cu9S5 / CGFS electromagnetic wave absorbing material, its preparation method, and its application. Background Technology

[0002] The unexpected advancement of wireless communication technology has accelerated the arrival of the artificial intelligence era. A pressing issue is the environmental pollution caused by the extensive use of electromagnetic waves. Developing wave-absorbing materials with highly efficient electromagnetic wave absorption properties using industrial waste is gradually becoming an effective and green solution to electromagnetic pollution. Based on the recycling of industrial waste, the development of novel carbon materials has been experimentally proven to be an effective way to prepare lightweight, thin, and highly efficient electromagnetic wave absorbers, while also ensuring sustainable energy development.

[0003] In the selection of absorber elements, coal gasification slag (CGFS) is a novel solid waste inevitably generated during coal gasification. After treatment, CGFS meets the requirements for use as a substrate material for absorber elements, and its high dielectric loss capacity makes it an excellent substrate material. Gao et al. synthesized hollow spherical Fe3O4 nanoparticles modified with CGFS using a hydrothermal strategy. This material exhibits excellent performance, with a minimum reflection loss (RL). min The value is -30.1 dB, and the maximum effective absorption bandwidth (EAB) is... max The value is 4.64 GHz. Zhang et al. prepared a ZnFe2O4 / residual carbon composite material, which has good radar stealth effect and excellent electromagnetic wave absorption performance (RL). min = -46.33dB, EAB max =2.96 GHz). However, like most carbon materials, the single CGFS has a simple loss path and poor impedance matching characteristics. Structural engineering can enhance the loss path, and Cu9S5 possesses strong electronic activity, which is conducive to generating electronic transition behavior. Its small band gap and diverse morphologies make it suitable for interface engineering. Chen et al. prepared Cu9S5@VO2 composite materials with a dual semiconductor heterojunction, which exhibited highly efficient electromagnetic wave absorption performance (RL). min = -56.98dB, EAB max =6.88GHz). Furthermore, Xu et al. prepared a multifunctional copper sulfide / carbon composite material derived from MOFs, whose RL... min = -62.3dB, EAB max =4.7GHz. Therefore, the object of this invention is to provide a new electromagnetic wave absorbing material based on CGFS. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, this invention proposes Cu9S5 / CGFS electromagnetic wave absorbing material, preparation method and application, which enhances the attenuation ability of composite materials, lays the foundation for green electromagnetic wave absorbing materials, and can be used as a candidate absorbing material for both military and civilian applications.

[0005] The method for preparing Cu9S5 / CGFS electromagnetic wave absorbing material proposed in this invention comprises the following steps:

[0006] S1: Coal gasification fine slag and CuCl2·2H2O are added sequentially to an ethanol aqueous solution to obtain mixed solution A;

[0007] S2: Dissolve Na2S·9H2O in an aqueous ethanol solution to obtain mixture B;

[0008] S3: Mix the mixture A of S1 and the mixture B of S2 and react them. After the reaction, the product is dried to obtain the Cu9S5 / CGFS composite material.

[0009] Preferably, the volume ratio of ethanol to deionized water in the ethanol aqueous solution in S1 and S2 is 1:1.5-2.5.

[0010] Preferably, the molar ratio of coal gasification fine slag, CuCl2·2H2O and Na2S·9H2O is 1g:15mmol-25mmol:15mmol.

[0011] Preferably, the reaction temperature in S3 is 130-150℃, and the reaction time is 10-14h.

[0012] The Cu9S5 / CGFS electromagnetic wave absorbing material prepared by the method proposed in this invention.

[0013] The present invention relates to the application of the Cu9S5 / CGFS electromagnetic wave absorbing material in microwave absorbing materials.

[0014] Beneficial technical effects of the present invention:

[0015] (1) This invention grows CGFS on polyhedral Cu9S5 particles using a simple one-step hydrothermal method, forming Cu9S5 / CGFS composite material. Guided by component synergy and interface engineering, the invention optimizes the poor impedance matching of CGFS as a single component, forming Cu9S5-Cu9S5 and Cu9S5-CGFS phase interfaces, and introduces interface polarization-dipole polarization to enhance the attenuation capability of the composite material. This is of great significance for limiting the excessively high conductivity of CGFS and enriching its multiple polarization losses, thus ensuring the sustainable development of green energy.

[0016] (2) The Cu9S5 / CGFS composite material prepared in this invention exhibits excellent electromagnetic wave absorption performance at 1.4 mm, achieving good scattering effect on radar waves (RL). min = -25.01dB, EAB max =3.52GHz, RCS attenuation value is 16.2dBm 2 (θ=0°)); The development of Cu9S5 / CGFS composite material has laid the foundation for green electromagnetic wave absorbing materials and can be used as a candidate absorbing material for both military and civilian applications. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the synthesis of the Cu9S5 / CGFS composite material proposed in this invention;

[0018] Figure 2 (a) XRD diffraction pattern and (b) Raman spectrum of the Cu9S5 / CGFS composite material proposed in this invention;

[0019] Figure 3 The following are the XPS spectra of CGFS and Cu9S5 / CGFS composite materials proposed in this invention: (a) XPS spectrum and (b) Cu 2p, (c) S 2p, (d) O 1s, and (e) C 1s spectra.

[0020] Figure 4 SEM images of (ac)CCS-1, (df)CCS-2, and (gi)CCS-3 of the Cu9S5 / CGFS composite material proposed in this invention, and an elemental distribution image of (j)CCS-2.

[0021] Figure 5 TEM images of (ac)CCS-1, (df)CCS-2, and (gi)CCS-3 of the Cu9S5 / CGFS composite material proposed in this invention, and an elemental distribution image of (j)CCS-2;

[0022] Figure 6 For the CGFS, CCS-1, CCS-2, and CCS-3 proposed in this invention, the following parameters are used: (a) ε′, (b) ε″, (c) μ′, (d) μ″, and (e) tanδ. ε 、(f)tanδ μ curve;

[0023] Figure 7 Two-dimensional reflection loss curves for (a) CGFS, (b) CCS-1, (c) CCS-2, and (d) CCS-3 proposed in this invention;

[0024] Figure 8The diagram shows the optimal electromagnetic wave absorption performance of (a) the Cu9S5 / CGFS composite material proposed in this invention, and (b) a comparison of electromagnetic wave absorption performance.

[0025] Figure 9 The Cole-Cole curves for (a) CGFS, (b) CCS-1, (c) CCS-2, and (d) CCS-3 proposed in this invention;

[0026] Figure 10 (a) impedance matching and (b) attenuation constant of the CGFS and Cu9S5 / CGFS composite materials proposed in this invention;

[0027] Figure 11 A schematic diagram of the electromagnetic absorption mechanism of the Cu9S5 / CGFS composite material proposed in this invention;

[0028] Figure 12 The following are the simulated RCS curves of the Cu9S5 / CGFS composite material proposed in this invention: (a) the RCS reduction of PEC after using the composite material; and (cf) the CST simulation results of the Cu9S5 / CGFS composite material. Detailed Implementation

[0029] The copper chloride dihydrate (CuCl2·2H2O, 99%), ethanol (CH3CH2OH, 99%), and sodium sulfide hydrate (Na2S·9H2O, 99%) used in the examples were all purchased from Aladdin Chemical Reagent Co., Ltd. (Shanghai, China), and all were of analytical grade (AR).

[0030] The present invention will be further explained below with reference to specific embodiments.

[0031] Example

[0032] A schematic diagram of the synthesis of the Cu9S5 / CGFS composite material proposed in this invention is shown below. Figure 1 As shown, the specific synthesis method is as follows: 0.2 g of treated CGFS was placed in a mixture of 16 mL deionized water and 8 mL ethanol, and then CuCl2·2H2O was added. 3.0 mmol of Na2S·9H2O was dissolved in a beaker containing 16 mL deionized water and 8 mL ethanol. Both solutions were sonicated for 30 minutes, and then mixed. The mixed solution immediately became a black suspension. The black suspension was then transferred to an autoclave and reacted at 140 °C for 12 hours. After the reaction, the product was collected and dried under vacuum overnight. The amounts of CuCl2·2H2O added were 3.0, 4.0, and 5.0 mmol, and the resulting products were designated as CCS-1, CCS-2, and CCS-3, respectively.

[0033] The properties of the prepared Cu9S5 / CGFS electromagnetic wave absorbing material were tested. The crystal structure of the polyhedral Cu9S5 / CGFS was analyzed by X-ray diffraction (XRD; D8-Advance, Cu-Ka radiation, Bruker Corporation, Japan). The degree of graphitization of the composite material was obtained by Raman spectroscopy (HORIBA Jobin Yvon, HR800, France). The morphology and microstructure of the samples were analyzed by scanning electron microscopy (SEM; FEI Sirion 2000, FEI Ltd., Netherlands) and transmission electron microscopy (TEM; FEI Talos F200X, EJTCO, Japan). The surface chemical elements and their spectral states of the samples were detected by X-ray photoelectron spectroscopy (XPS; Thermo Fisher Scientific ESCALABMK, USA). Four sets of samples were fabricated into ring pillars with a thickness of 2.0 mm. Electromagnetic parameters were measured using a vector network analyzer (AV 3629D, 41st Research Institute of China Electronics Technology Group Corporation). The ratio of sample to paraffin was 60%:40%. RCS simulation is performed using computer simulation technology tools.

[0034] By analyzing the XRD diffraction pattern of a material, information about its crystal structure can be obtained. For example... Figure 2 As shown in (a), the CGFS diffraction pattern results show that the diffraction peak at 26.1° is consistent with the characteristic peak of the (002) crystal plane of graphite carbon. Another peak at around 43° is the characteristic peak of the (100) crystal plane of graphite. After Cu9S5 is compounded, the intensity of the CGFS diffraction peaks becomes blurred due to the excellent crystallinity of Cu9S5. According to the standard card (JCPDS card number 47-1748), the diffraction peaks at 27.8°, 29.2°, 32.2°, 41.5°, 46.2° and 54.7° can be attributed to the (0015), (107), (1010), (0117), (110) and (1115) crystal planes, respectively. The excellent crystallization results help to control the morphology of the material.

[0035] The results of Raman spectroscopy of materials can be used to analyze the degree of defects in CGFS and its composites. Generally speaking, I D / I G The larger the ratio, the greater the degree of defect. A higher degree of defect is more conducive to the generation of dipole polarization centers, thus effectively attenuating electromagnetic fields. Figure 2 (b) shows that as the proportion of CGFS decreases, I D / I G The value gradually decreased from 1.22 to 0.88, which is consistent with the actual situation. Meanwhile, the microwave absorption performance of the absorbing material is the result of the synergistic effect of multiple components and multiple effects.

[0036] XPS results were used to analyze the elemental composition and bonding modes of the surface phases of composite materials. Figure 3 As shown in (a), the composite material mainly contains four elements: C, O, Cu, and S. In the deconvolution results of C, 284.5, 286.5, and 288.5 eV are assigned to CC / C=C, C-OH, and C=O, respectively. After Cu9S5 is composited with CGFS, the characteristic peak shifts from 285.5 eV to 286.5 eV, which is due to the high-temperature oxidation reaction during the hydrothermal process converting C-OH to CO. Correspondingly, the distribution of the characteristic peaks of O is as follows: 530.2, 532.2, and 534.3 eV correspond to the three bonding states of CO, C=O, and -OH, respectively. After synthesis, the stable electrons shifted by 0.3 eV, presumably due to testing errors during the sampling process. In the deconvolution results of Cu, 932.3 and 952.1 eV can be assigned to Cu. + The corresponding Cu 2p 3 / 2 and Cu 2p 1 / 2 and with Cu 2+ The corresponding valence values ​​of 934.2 and 954.2 eV together constitute the valence states of Cu in Cu9S5. The S elements at 161.8 and 163.2 eV correspond to S²p, respectively. 3 / 2 and S2p 1 / 2 The S2s at 168.3 eV is due to the oxidation of the S surface in air. Analysis of the XPS results indicates that Cu9S5 exhibits excellent chemical bonding, and the hydrothermal synthesis of CGFS and Cu9S5 presents conditions for the formation of dipole polarization, which is beneficial for increasing the number of active sites in the composite material.

[0037] Scanning electron microscopy (SEM) images of the composite material allow for analysis of its morphology and microstructure. Cu9S5 particles exhibit a polyhedral structure. The autonomous aggregation of Cu particles initially forms a plate-like hexahedral structure, followed by autonomous stacking to form a polyhedral structure. During hydrothermal processing, sulfidation occurs, forming Cu9S5 polyhedral particles with a particle size maintained at 500 nm. Through ion exchange reactions and electrostatic self-assembly with CGFS, the free energy of the Cu9S5 surface tends to decrease, ultimately forming a Cu9S5 framework and an external CGFS layer. Figure 4 (f)). The Cu9S5 and CGFS are tightly bonded, forming numerous heterojunction interfaces, which is conducive to the generation of interfacial polarization. Furthermore, CCS-2 was characterized using spectral mapping, such as... Figure 4 As shown in (j), C and O elements are uniformly distributed throughout the space. Cu elements are mainly concentrated in the polyhedral portion, while S elements are also widely distributed throughout the space, which is believed to be due to ion exchange with CGFS during the sulfidation process.

[0038] TEM results can be used to analyze the microstructure of materials at a more microscopic level. In CCS-1, the layered structure of Cu9S5 is very obvious and can be analyzed as lattice fringes of the (101) crystal plane of Cu9S5 with a lattice spacing of 0.339 nm. However, no lamellar structure was observed in CCS-2 and CCS-3, with Cu... 2+ With increasing addition, copper particles were able to fully form. In the lattice fringes of CCS-2, both the (101) crystal plane of Cu9S5 and the (101) crystal plane of carbon material were observed simultaneously. Figure 5 (ai)), with a lattice spacing of 0.204 nm. TEM mapping results show a reasonable distribution of elements, consistent with SEM results. Combined with previous characterization results, the two composite materials are found to be in excellent condition, exhibiting numerous polarization behavior conditions. SEM results further indicate that the morphology and structure of the composite materials are highly conducive to interface engineering between components, thereby enhancing electromagnetic wave loss.

[0039] Obtaining electromagnetic parameters is the primary method for evaluating the microwave absorption capability of absorbing materials. The real part (ε', μ') represents the evaluation of the electromagnetic wave storage capability, while the imaginary part (ε", μ") represents the evaluation of the electromagnetic wave attenuation capability. From... Figure 6 (af) It can be seen that the electromagnetic parameters of all samples exhibit a significant dispersion effect. The mixing ratio of the material and paraffin is 60%. CGFS, CCS-1, and CCS-2 all exhibit significant relaxation behavior, confirming the presence of significant polarization behavior within the material. It can be seen that as the loading proportion of CGFS decreases, the dielectric constants of CCS-1 and CCS-2 show a significant decreasing trend. However, when the proportion of Cu9S5 is particularly high, the dielectric constant rebounds, which is due to the relatively high dielectric constant of Cu9S5. Tanδ ε It is one of the important indicators for evaluating the loss capacity of absorbers. And the presence of a resonance peak in CCS-2 is one of the reasons for its superior performance.

[0040] RL min The value is a more intuitive indicator of absorber performance, which can be obtained through simulation analysis of electromagnetic parameters. Figure 7 (ad)). CGFS's RL min The value is -10.46dB, indicating a very narrow bandwidth. The performance of Cu9S5 was improved to varying degrees after composite processing. CCS-2, in particular, showed better coating results; at a thickness of 1.4mm, the RL... min The value is -25.01dB, EAB max The value is 3.52GHz, even with a thickness of 2.1mm, RL minThe value is as high as -56.56 dB, and a double absorption peak appears at 2.4 mm. The ultrawide Fe of CCS-3 reaches 14.16 GHz. From the performance analysis, the introduction of Cu9S5 is very effective in enhancing the material performance, and interface engineering, interface engineering, and component synergy strategies all play a role.

[0041]

[0042] Among them, Z in Z0 and Z0 are the input impedance and free space impedance, respectively. f is the electromagnetic wave frequency, d is the absorber thickness, and c is the speed of light.

[0043] To better highlight the performance comparison results of this work compared to other works, as follows: Figure 8 As shown in (a) and (b), CCS-2 outperforms some carbon composite materials, such as CNT and biochar. Compared with Cu9S5 alone, its performance is also greatly improved, especially in terms of the thickness of the absorbing material. Therefore, this work not only compensates for the deficiencies of both components but also meets green and environmentally friendly requirements.

[0044] To better analyze whether relaxation behavior exists within the material, an ε'-ε' curve can be plotted based on the dielectric constant. Figure 9 (ad)). Typically, the curve exhibits an irregular semicircle due to interference from material conductivity. A straight line with a certain slope appears at the tail of the curve, representing the dielectric loss of the material. Surprisingly, CGFS exhibits significant relaxation behavior, but its dielectric loss capability is relatively average. CSS-3 is primarily characterized by dielectric loss, while CSS-2 shows the strongest relaxation capability, forming a perfect semicircle. This is because the surface of CGFS contains abundant hydroxyl and carboxyl groups, as well as numerous defects, which effectively induce Debye relaxation behavior. After Cu9S5 composite, a large amount of interfacial polarization behavior is generated on top of the original advantages of CGFS, giving CCS-2 the best absorption characteristics. Debye relaxation can be described by the formula:

[0045]

[0046] Excellent impedance matching characteristics of the absorber are the primary condition for ensuring that electromagnetic waves can penetrate the material as much as possible. Optimal performance is achieved only when the input impedance (air) and the internal impedance of the material satisfy the impedance normalization condition (Equation 2). After entering the material, the electromagnetic waves need to be attenuated as much as possible; the loss constant (α) is the most intuitive indicator (Equation 3). The combination of impedance matching and attenuation constant gives the absorber superior performance. It can be seen that the attenuation constant of CCS-2 is not as high as that of CGFS, but its impedance matching performance is the best. Considering both performance characteristics, CCS-2 has the best overall performance. (RL) min= -56.56dB, EAB max =3.52GHz).

[0047]

[0048]

[0049] After comprehensively analyzing the chemical information, morphology, electromagnetic wave absorption properties, and absorption characteristics of the material, the electromagnetic wave absorption characteristics of the core-shell Cu9S5 / CGFS nanocomposite can be summarized as follows: Figure 11 (I) Polyhedral Cu9S5 / CGFS particles formed by self-assembled CGFS coating undergo multiple scattering and reflections between particles when electromagnetic waves are incident, with a very small portion being transmitted. (II) The outer coating of CGFS possesses the excellent properties of carbon materials, forming a highly conductive network that facilitates electron transition behavior and enhances the impedance matching characteristics and dielectric loss capability of the material. (III) A large number of heterojunction interfaces are formed between the CGFS and Cu9S5 phases. Polyhedral Cu9S5 is assembled from plate-like hexahedral Cu9S5, and interfacial polarization also exists between the plates. A large number of heterocharges accumulate between the phase interfaces, resulting in strong polarization behavior. (IV) The surface of CGFS contains a large number of carboxyl and hydroxyl groups, which are conducive to the generation of dipole polarization centers. Moreover, these two groups also undergo ion exchange behavior during hydrothermal processes, thereby inducing dipole polarization behavior and defect-induced dipole polarization loss.

[0050] Radar cross section (RCS) can be used to broaden the application scenarios of absorbing materials and evaluate the radar echo intensity of absorbing materials in the far field. In applications, the effect when the radar wave forms a small angle with the material matrix is ​​used as the main evaluation reference. In the simulation, a PEC board (180*180mm) is used as the substrate. 2 (d=1.0mm), using Cu9S5 / CGFS composite material as the coating plate (180*180mm) 2 , d=1.4mm, f=16.16(11.04)GHz). Figure 12 (a) Shows the RCS reduction values ​​of PEC, CCS-1, CCS-2, CCS-2' (f = 11.04 GHz), and CCS-3 in the range of -80 to 80°. At θ = 0°, the lowest attenuation value of CCS-2' is 16.2 dBm. 2 This is consistent with previous results, as the same attenuation mechanism also applies to this material (θ = 0°). S is the area of ​​the simulation model, E s and E iThese are the electric field strengths of the scattered wave and the incident wave, respectively. Meanwhile, after the composite plate is coated with Cu9S5 / CGFS absorbing agent, its attenuation capability for radar waves is also improved to varying degrees. Figure 12 b). Cu9S5 / CGFS materials have great application potential in both military and civilian fields.

Claims

1. A method for preparing Cu9S5 / CGFS electromagnetic wave absorbing material, characterized in that, The steps are as follows: S1: Coal gasification fine slag and CuCl2·2H2O are added sequentially to an ethanol aqueous solution to obtain mixed solution A; S2: Dissolve Na2S·9H2O in an aqueous ethanol solution to obtain mixture B; S3: Mix the mixture A of S1 and the mixture B of S2 and react them. After the reaction, the product is dried to obtain the Cu9S5 / CGFS composite material. The mass molar ratio of coal gasification fine slag, CuCl2·2H2O and Na2S·9H2O is 1g:15mmol-25mmol:15mmol; The reaction temperature in S3 is 130-150℃, and the reaction time is 10-14h.

2. The preparation method of Cu9S5 / CGFS electromagnetic wave absorbing material according to claim 1, characterized in that, The volume ratio of ethanol to deionized water in the ethanol aqueous solutions of S1 and S2 is 1:1.5-2.

5.

3. Cu9S5 / CGFS electromagnetic wave absorbing material prepared by the method described in claim 1 or 2.

4. The application of the Cu9S5 / CGFS electromagnetic wave absorbing material as described in claim 3 in microwave absorbing materials.

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