A method for preparing graphene / metal oxide microwave absorbing materials with ultra-rapid freezing-strengthened heterostructures and its application.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-17
- Publication Date
- 2026-08-14
AI Technical Summary
[0007]上述制备方法存在些许局限：一方面对原料种类与工艺参数要求较高，如需要加入吡咯，需要加入氨水、聚乙烯吡咯烷酮，以及Fe3O4纳米球需进行表面正电化处理，原料种类较复杂；另一方面传统冷冻干燥采用的缓慢冷冻方式容易导致金属离子团聚，降低界面结合的强度和质量
（1）本发明采用了氧化石墨烯分散液和水溶性金属盐溶液两种简单的原料，不需要再加入其它任何原料，然后采用快速低温冷冻处理，最后热处理就能石墨烯/金属氧化物异质结构吸波材料。
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Figure CN122579592A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing graphene / metal oxide microwave absorbing materials with ultra-rapid freezing-strengthened heterostructures and their applications, belonging to the field of electromagnetic functional materials technology. Background Technology
[0002] Microwave absorbing materials are a class of materials capable of dissipating the energy of electromagnetic waves entering their interior as heat or other forms of energy, playing an indispensable role in electromagnetic protection, stealth technology, and other fields. Excellent electromagnetic wave absorbing materials require good impedance matching and strong attenuation capabilities. Their energy loss mechanisms mainly encompass two core types: dielectric loss and magnetic loss. In the dielectric loss mechanism, constructing stable heterostructures to enhance the interfacial polarization effect can significantly improve electromagnetic wave attenuation efficiency, representing a key path to optimizing the overall performance of microwave absorbing materials.
[0003] Graphene / metal oxide composite absorbing materials effectively compensate for the shortcomings of pure graphene, such as poor impedance matching and a single loss mechanism, by leveraging the synergistic loss effect of carbon-based and metal oxide materials, exhibiting excellent performance in terms of absorption intensity and bandwidth.
[0004] Application No. 2021108147220 describes a graphene-ferrite composite aerogel microwave absorbing material and its preparation method. First, Fe-MOF was prepared, then graphene oxide aqueous solution and pyrrole were added to Fe-MOF, and finally the material was aged and frozen to obtain the graphene / ferrite aerogel microwave absorbing material.
[0005] Application number 2025107842776 discloses a method for preparing Fe3O4 / reduced graphene oxide composite microwave absorbing material. The method involves mixing graphene oxide solution and ethylene glycol, dispersing them evenly to obtain a suspension; adding ferric chloride to the suspension, dispersing it evenly, adding ammonia and polyvinylpyrrolidone, mixing and reacting to obtain a product; washing, centrifuging, freeze-drying, and heat-treating the product to prepare the Fe3O4 / reduced graphene oxide composite microwave absorbing material.
[0006] Application number 202511850724X discloses a method for preparing a composite microwave absorbing material. First, a graphene oxide dispersion is obtained; then, Fe3O4 nanospheres are subjected to surface positive electrochemical treatment and dispersed; the two dispersions are mixed, and a conductive two-dimensional material solution is added; finally, the mixture is freeze-dried to obtain a three-dimensional magnetic composite microwave absorbing material.
[0007] The above preparation method has some limitations: on the one hand, it has high requirements for the types of raw materials and process parameters. For example, it requires the addition of pyrrole, ammonia, polyvinylpyrrolidone, and Fe3O4 nanospheres need to undergo surface positive electrochemical treatment, making the types of raw materials more complex; on the other hand, the slow freezing method used in traditional freeze drying can easily lead to the aggregation of metal ions, reducing the strength and quality of interfacial bonding. Summary of the Invention
[0008] To address the problems and shortcomings of the existing technologies, this invention provides a method for preparing graphene / metal oxide absorbing materials with ultra-rapid freezing-enhanced heterostructures and their applications. This invention uses only two simple raw materials: graphene oxide dispersion and water-soluble metal salt solution, without adding any other raw materials. Rapid low-temperature freezing followed by heat treatment yields a graphene / metal oxide heterostructure absorbing material with a minimum absolute reflection loss ≥20dB and an effective absorption bandwidth >4GHz. This invention is achieved through the following technical solution.
[0009] A method for preparing graphene / metal oxide microwave absorbing material with ultra-rapid freezing-strengthened heterogeneous interface includes the following steps: preparing graphene oxide dispersion and water-soluble metal salt solution, mixing and stirring; obtaining a precursor by rapid low-temperature freezing and drying; and finally obtaining the graphene / metal oxide microwave absorbing material by heat treatment under an inert protective gas atmosphere.
[0010] The concentration of the graphene oxide dispersion is 1~5 mg / mL; the concentration of the water-soluble metal salt solution is 0.01~0.1 mol / L; and the volume ratio of the graphene oxide dispersion to the water-soluble metal salt solution is 5:1~10:3.
[0011] The mixing and stirring are carried out at a constant temperature of 30~60℃.
[0012] The water-soluble metal salt is a water-soluble copper salt, a water-soluble nickel salt, or a water-soluble zinc salt.
[0013] The water-soluble copper salt is one or more of copper acetate, copper nitrate, copper sulfate, and copper chloride in any proportion; The water-soluble nickel salt is one or more of nickel acetate, nickel nitrate, nickel sulfate, and nickel chloride in any proportion; The water-soluble zinc salt is one or more of zinc acetate, zinc nitrate, zinc sulfate, and zinc chloride in any proportion.
[0014] The rapid cryogenic freezing method employs one of the following: liquid nitrogen quick-freezing, liquid helium quick-freezing, or ultra-low temperature instantaneous freezing below -80°C, with a freezing time ≤10 minutes.
[0015] The inert protective gas atmosphere is argon or nitrogen.
[0016] A graphene / metal oxide microwave absorbing material, prepared by the above method, has a minimum absolute reflection loss ≥20dB, an effective absorption bandwidth >4GHz, and a graphene / copper oxide effective absorption bandwidth up to 7.12GHz.
[0017] An application of a graphene / metal oxide microwave absorbing material in the fields of electromagnetic protection or stealth technology.
[0018] The principle of this invention is as follows: A simple graphene oxide dispersion (GO dispersion) and a water-soluble metal salt solution, during freeze-drying, achieve instantaneous cooling of the system through rapid low-temperature freezing. This allows the water in the system to solidify into tiny ice crystals in a very short time, avoiding the compression of GO sheets by water crystallization during traditional slow freezing. Simultaneously, it inhibits the concentration and aggregation of metal ions caused by water migration, ensuring that metal ions are uniformly loaded on the GO sheet surface. This uniform dispersion significantly shortens the heterogeneous nucleation cycle in the subsequent heat treatment stage, allowing oxygen-containing functional groups on the GO surface to quickly become preferential nucleation sites, inducing efficient heterogeneous nucleation of metal ions, forming a tightly bound and structurally stable heterogeneous interface, and significantly enhancing interfacial polarization. Finally, through process optimization, the electromagnetic absorption performance of the sample is effectively improved, achieving the stable preparation of high-performance microwave absorbing materials.
[0019] The beneficial effects of this invention are: (1) This invention uses two simple raw materials: graphene oxide dispersion and water-soluble metal salt solution. No other raw materials need to be added. Then, rapid low-temperature freezing treatment is used, and finally heat treatment is used to obtain graphene / metal oxide heterostructure microwave absorbing material.
[0020] (2) This invention is applicable to various metal salt precursors such as water-soluble copper salt, water-soluble nickel salt and water-soluble zinc salt, and can realize the construction of different heterostructure microwave absorbing materials such as graphene / copper oxide, graphene / nickel oxide and graphene / zinc oxide. Compared with the existing technology which mainly focuses on ferrite / graphene system, it significantly broadens the preparation system and application range of graphene-based metal oxide composite microwave absorbing materials.
[0021] (3) This method has wide applicability to the construction of graphene / metal oxide heterostructures, and can greatly broaden the concentration range of GO dispersion and water-soluble metal salt, and is compatible with a variety of water-soluble metal salt raw materials.
[0022] (4) This method solves the problem of metal ion aggregation from the source by ultra-fast freezing, and strengthens heterogeneous nucleation and interfacial polarization. The resulting graphene / metal oxide heterostructure microwave absorbing material has strong interfacial interaction, with a minimum absolute value of reflection loss ≥20dB and an effective absorption bandwidth >4GHz. Among them, the effective absorption bandwidth of graphene / copper oxide can reach 7.12GHz. Attached Figure Description
[0023] Figure 1 These are XRD patterns of the graphene / copper oxide prepared in Example 1 and Comparative Example 1.
[0024] Figure 2 The images show SEM and EDS images (low magnification to 50,000 magnification) of the graphene / copper oxide precursor prepared in Comparative Example 1.
[0025] Figure 3 These are SEM and EDS images (low magnification to 50,000 magnification) of the graphene / copper oxide precursor prepared in Example 1. Detailed Implementation
[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0027] The method for preparing graphene / metal oxide microwave absorbing material with ultra-rapid freezing-strengthened heterostructure includes the following steps: preparing graphene oxide dispersion and water-soluble metal salt solution, mixing and stirring; obtaining the precursor by rapid low-temperature freezing and drying; and finally obtaining the graphene / metal oxide microwave absorbing material by heat treatment under an inert protective gas atmosphere.
[0028] In some embodiments, the concentration of the graphene oxide dispersion is 1~5 mg / mL. In some specific embodiments, for example, the concentration of the graphene oxide dispersion is 1 mg / mL, 2 mg / mL, 3 mg / mL, or 5 mg / mL; the concentration of the water-soluble metal salt solution is 0.01~0.1 mol / L. In some specific embodiments, for example, the concentration of the water-soluble metal salt solution is 0.01 mol / L, 0.02 mol / L, 0.05 mol / L, or 0.1 mol / L; the volume ratio of the graphene oxide dispersion to the water-soluble metal salt solution is 5:1~10:3. In some specific embodiments, for example, the volume ratio of the graphene oxide dispersion to the water-soluble metal salt solution is 5:1, 10:3, 5:2, or 10:1.
[0029] In some embodiments, the mixing and stirring is carried out at a constant temperature of 30~60°C. In certain specific embodiments, for example, the mixing and stirring is carried out at a constant temperature of 30°C, 40°C, 50°C or 60°C.
[0030] In some embodiments, the water-soluble metal salt is a water-soluble copper salt, a water-soluble nickel salt, or a water-soluble zinc salt.
[0031] In some embodiments, the water-soluble copper salt is one or more of copper acetate, copper nitrate, copper sulfate, and copper chloride in any proportion; in some specific embodiments, for example, a mixture of copper acetate and copper nitrate in a mass ratio of 1:1, or a mixture of copper sulfate and copper chloride in a mass ratio of 1:1. The water-soluble nickel salt is one or more of nickel acetate, nickel nitrate, nickel sulfate, and nickel chloride in any proportion; in some specific embodiments, it is a mixture of nickel acetate and nickel nitrate in a mass ratio of 1:1, or a mixture of nickel sulfate and nickel chloride in a mass ratio of 1:1.
[0032] The water-soluble zinc salt is one or more of zinc acetate, zinc nitrate, zinc sulfate, and zinc chloride in any proportion. In some specific embodiments, it is a mixture of zinc acetate and zinc nitrate in a mass ratio of 1:1, or a mixture of zinc sulfate and zinc chloride in a mass ratio of 1:1.
[0033] The rapid cryogenic freezing method employs one of the following: liquid nitrogen quick-freezing, liquid helium quick-freezing, or ultra-low temperature instantaneous freezing below -80°C, with a freezing time ≤10 minutes.
[0034] The inert protective gas atmosphere is argon or nitrogen. Example 1
[0035] The preparation method of graphene / metal oxide microwave absorbing material with ultra-rapid freezing-strengthened heterostructure is as follows: Using graphene oxide (GO) as the substrate, Cu(CH3COO)2·H2O as the Cu 2+ Source: First, prepare a 2 mg / mL GO dispersion and a 0.05 mol / L Cu(CH3COO)2·H2O solution; then mix and stir the two at a volume ratio of 10:3 at 40℃; freeze-dry in liquid nitrogen for 10 min to obtain the precursor; finally, heat-treat at 250℃ for 120 min at a heating rate of 5℃ / min under an argon atmosphere to obtain a graphene / copper oxide heterostructure microwave absorbing material with a minimum absolute reflection loss of 28dB and an effective absorption bandwidth of 7.12GHz.
[0036] The XRD pattern of the graphene / copper oxide heterostructure microwave absorbing material prepared in this embodiment is shown below. Figure 1 As shown in CC-15, from Figure 1 As can be seen, a broad diffraction peak of reduced graphene oxide appears near 26°, and peaks resembling those of Cu appear at 36.4°, 42.3°, 61.3°, and 73.5°, respectively. 2+1 The diffraction peaks corresponding to the (111), (200), (220), and (311) crystal planes of O (PDF#05-0667) show more significant diffraction characteristics; the SEM and EDS images of the prepared graphene / copper oxide precursor are shown in Figure 3. Figure 3 The data shows that the precursor sample particles are relatively uniform, and no obvious agglomeration was observed. Combined with the corresponding EDS elemental distribution map, it can be seen that Cu is uniformly distributed.
[0037] Comparative Example 1 This comparative example uses the traditional slow freeze-drying method (slow freezing at -40℃ for 48 hours), and the steps are as follows: Using graphene oxide (GO) as the substrate, Cu(CH3COO)2·H2O as the Cu 2+ Source: First, a 2 mg / mL GO dispersion and a 0.05 mol / L Cu(CH3COO)2·H2O solution were prepared; then, the two were mixed and stirred at a volume ratio of 10:3 at 40℃; the precursor was obtained by freeze-drying at -40℃; finally, the precursor was heat-treated to 250℃ for 120 min at a heating rate of 5℃ / min under an argon atmosphere to obtain a graphene / copper oxide heterostructure microwave absorbing material with a minimum absolute reflection loss of 28 dB and an effective absorption bandwidth of 5.82 GHz.
[0038] The XRD pattern of the graphene / copper oxide heterostructure microwave absorbing material in this embodiment is shown below. Figure 1 As shown in CCD15, from Figure 1 As can be seen, a broad diffraction peak of reduced graphene oxide appears near 26°, and peaks resembling those of Cu appear at 36.4°, 42.3°, 61.3°, and 73.5°, respectively. 2+1 The diffraction peaks corresponding to the (111), (200), (220), and (311) crystal planes of O (PDF#05-0667) show a certain degree of broadening and weakening; the SEM and EDS images of the prepared graphene / copper oxide precursor are shown below. Figure 2 As shown, from Figure 2 The precursor sample exhibits irregular particle aggregation. Combined with the corresponding EDS elemental distribution map, it can be seen that Cu is unevenly distributed and exhibits localized enrichment.
[0039] In Comparative Example 1, the performance of the graphene / copper oxide heterostructure absorbing material that underwent conventional slow cooling was significantly lower than that of the graphene / copper oxide heterostructure absorbing material in Example 1. Example 2
[0040] The preparation method of graphene / metal oxide microwave absorbing material with ultra-rapid freezing-strengthened heterostructure is as follows: Using graphene oxide (GO) as the substrate and CuSO4 as the Cu content, 2+ Source: First, a 1 mg / mL GO dispersion and a 0.01 mol / L CuSO4 solution were prepared; then, the two were mixed and stirred at a volume ratio of 10:1 at 50℃; the precursor was obtained by freeze-drying in liquid helium for 10 min; finally, the precursor was heat-treated to 250℃ for 150 min at a heating rate of 10℃ / min under an argon atmosphere to obtain a graphene / zinc oxide heterostructure microwave absorbing material with a minimum absolute reflection loss of 32 dB and an effective absorption bandwidth of 6.33 GHz. Example 3
[0041] The preparation method of graphene / metal oxide microwave absorbing material with ultra-rapid freezing-strengthened heterostructure is as follows: Using graphene oxide (GO) as the substrate and Cu(NO3)2 as the Cu... 2+ Source: First, a 3 mg / mL GO dispersion and a 0.02 mol / L Cu(NO3)2 solution were prepared; then, the two were mixed and stirred at a volume ratio of 5:2 at 60℃; the precursor was obtained by instantaneous freeze-drying at -80℃ for 10 min; finally, the precursor was heat-treated to 250℃ for 130 min at a heating rate of 3℃ / min under an argon atmosphere to obtain a graphene / copper oxide heterostructure microwave absorbing material with a minimum absolute reflection loss of 38 dB and an effective absorption bandwidth of 6.13 GHz. Example 4
[0042] The preparation method of graphene / metal oxide microwave absorbing material with ultra-rapid freezing-strengthened heterostructure is as follows: Using graphene oxide (GO) as the substrate and Ni(CH3COO)2 as the Ni 2+ Source: First, a 2 mg / mL GO dispersion and a 0.05 mol / L Ni(CH3COO)2 solution were prepared; then, the two were mixed and stirred at a volume ratio of 10:3 at 40℃; the precursor was obtained by freeze-drying in liquid nitrogen for 8 min; finally, the precursor was heat-treated to 300℃ for 120 min at a heating rate of 5℃ / min under an argon atmosphere to obtain a graphene / nickel oxide heterostructure microwave absorbing material with a minimum absolute reflection loss of 65 dB and an effective absorption bandwidth of 4.04 GHz. Example 5
[0043] The preparation method of graphene / metal oxide microwave absorbing material with ultra-rapid freezing-strengthened heterostructure is as follows: Using graphene oxide (GO) as the substrate and NiSO4 as Ni 2+ Source: First, a 3 mg / mL GO dispersion and a 0.02 mol / L NiSO4 solution were prepared; then, the two were mixed and stirred at a volume ratio of 5:2 at 60℃; the precursor was obtained by freeze-drying in liquid helium for 6 min; finally, the precursor was heat-treated to 300℃ for 150 min at a heating rate of 2℃ / min under an argon atmosphere to obtain a graphene / nickel oxide heterostructure microwave absorbing material with a minimum absolute reflection loss of 20 dB and an effective absorption bandwidth of 4.08 GHz. Example 6
[0044] The preparation method of graphene / metal oxide microwave absorbing material with ultra-rapid freezing-strengthened heterostructure is as follows: Using graphene oxide (GO) as the substrate, Zn(CH3COO)2·2H2O is used as Zn 2+ Source: First, a 2 mg / mL GO dispersion and a 0.05 mol / L Zn(CH3COO)2·2H2O solution were prepared; then, the two were mixed and stirred at a volume ratio of 10:3 at 40℃; the precursor was obtained by freeze-drying in liquid nitrogen for 8 min; finally, the precursor was heat-treated to 550℃ for 120 min at a heating rate of 5℃ / min under an argon atmosphere to obtain a graphene / zinc oxide heterostructure microwave absorbing material with a minimum absolute reflection loss of 29 dB and an effective absorption bandwidth of 4.42 GHz. Example 7
[0045] The preparation method of graphene / metal oxide microwave absorbing material with ultra-rapid freezing-strengthened heterostructure is as follows: Using graphene oxide (GO) as the substrate and ZnCl2 as Zn 2+ Source: First, a 1 mg / mL GO dispersion and a 0.05 mol / L ZnCl2 solution were prepared; then, the two were mixed and stirred at a volume ratio of 5:2 at 50℃; the precursor was obtained by instantaneous freezing at -80℃ for 8 min; finally, the precursor was obtained by heat treatment at 550℃ for 130 min under an argon atmosphere at a heating rate of 3℃ / min. A graphene / zinc oxide heterostructure microwave absorbing material with a minimum absolute reflection loss of 31 dB and an effective absorption bandwidth of 4.37 GHz was obtained.
[0046] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.
Claims
1. A method for preparing graphene / metal oxide microwave absorbing materials with ultra-rapid freezing-strengthened heterostructures, characterized by the following steps: include: Prepare a graphene oxide dispersion and a water-soluble metal salt solution, and mix and stir. The precursor was obtained by rapid low-temperature freeze-drying. Finally, the graphene / metal oxide microwave absorbing material was obtained by heat treatment under an inert protective gas atmosphere.
2. The method for preparing graphene / metal oxide microwave absorbing material with ultra-rapid freezing-strengthened heterostructure according to claim 1, characterized in that: The concentration of the graphene oxide dispersion is 1~5 mg / mL; the concentration of the water-soluble metal salt solution is 0.01~0.1 mol / L; and the volume ratio of the graphene oxide dispersion to the water-soluble metal salt solution is 5:1~10:
3.
3. The method for preparing graphene / metal oxide microwave absorbing material with ultra-rapid freezing-strengthened heterostructure according to claim 1, characterized in that: The mixing and stirring are carried out at a constant temperature of 30~60℃.
4. The method for preparing graphene / metal oxide microwave absorbing material with ultra-rapid freezing-strengthened heterostructure according to claim 2, characterized in that: The water-soluble metal salt is a water-soluble copper salt, a water-soluble nickel salt, or a water-soluble zinc salt.
5. The method for preparing graphene / metal oxide microwave absorbing material with ultra-rapid freezing-strengthened heterostructure according to claim 4, characterized in that: The water-soluble copper salt is one or more of copper acetate, copper nitrate, copper sulfate, and copper chloride in any proportion; The water-soluble nickel salt is one or more of nickel acetate, nickel nitrate, nickel sulfate, and nickel chloride in any proportion; The water-soluble zinc salt is one or more of zinc acetate, zinc nitrate, zinc sulfate, and zinc chloride in any proportion.
6. The method for preparing graphene / metal oxide microwave absorbing material with ultra-rapid freezing-strengthened heterostructure according to claim 1, characterized in that: The rapid cryogenic freezing method employs one of the following: liquid nitrogen quick-freezing, liquid helium quick-freezing, or ultra-low temperature instantaneous freezing below -80°C, with a freezing time ≤10 minutes.
7. The method for preparing graphene / metal oxide microwave absorbing material with ultra-rapid freezing-strengthened heterostructure according to claim 1, characterized in that: The inert protective gas atmosphere is argon or nitrogen.
8. The method for preparing graphene / metal oxide microwave absorbing material with ultra-rapid freezing-strengthened heterostructure according to claim 1, characterized in that: The heat treatment is performed by heating to 250-550℃ at a rate of 1-10℃ / min for 120-150 min.
9. A graphene / metal oxide microwave absorbing material, characterized in that: Prepared by any one of the preparation methods described in claims 1 to 8, the minimum absolute value of reflection loss is ≥20dB, and the graphene / copper oxide effective absorption bandwidth is up to 7.12GHz.
10. An application of the graphene / metal oxide absorbing material according to claim 9, for use in the fields of electromagnetic protection or stealth technology.