Pyrophosphate / carbon nano composite wave-absorbing material with two-dimensional heterostructure as well as preparation method and application of pyrophosphate / carbon nano composite wave-absorbing material

Abstract

The invention provides a pyrophosphate / carbon nano composite wave-absorbing material with a two-dimensional heterostructure as well as a preparation method and application of the pyrophosphate / carbon nano composite wave-absorbing material, and belongs to the field of nano materials. In-situ construction of pyrophosphate and a carbon heterogeneous interface is achieved through high-temperature pyrolysis of phosphate MOF, polarization loss is further adjusted by changing the types of metal ions, and then the electromagnetic wave absorption performance is improved. The two-dimensional heterostructure pyrophosphate / carbon nano composite wave-absorbing material prepared by the preparation method disclosed by the invention shows excellent electromagnetic wave absorption performance. The pyrophosphate / carbon nano composite wave-absorbing material has the characteristics of light weight, low cost and good wave-absorbing performance, and can be used as a wave-absorbing agent.

Description

Technical Field

[0001] The present invention belongs to the field of nanomaterials, and specifically relates to a two-dimensional heterostructure pyrophosphate / carbon nanocomposite microwave absorbing material, its preparation method and application. Background Art

[0002] With the rapid development of electronic information technology, wireless communication, Internet of Things, and 5G / 6G technologies have gradually become popular, and the application of electromagnetic waves has penetrated into all aspects of modern society. However, the problems of electromagnetic interference and electromagnetic radiation pollution caused by electromagnetic devices are becoming increasingly serious, which not only pose a threat to the normal operation of electronic devices, but also may bring potential risks to human health. To address this challenge, electromagnetic compatibility technology has emerged, and its key lies in using electromagnetic shielding or absorbing materials to suppress the reflection and propagation of electromagnetic waves. Among them, the research and development of high-efficiency electromagnetic wave absorbing materials has become the core approach to solve this problem.

[0003] Heterostructures have become the core direction of the development of electromagnetic wave absorbing materials through multi-component synergy, enhanced interfacial polarization, and optimized structural design. However, their widespread application is still limited by the balance of frequency band-thickness, preparation cost, and insufficient theoretical research. Laboratory preparation methods (such as freeze-drying, high-temperature carbonization) are costly and difficult to mass-produce. For example, the synthesis of rGO / CFs involves multiple steps of freeze-drying and carbonization processes. In addition, some heterostructures rely on rare elements (such as rare earths), which limits their environmental friendliness. In-situ construction technology provides a feasible path to break through these bottlenecks by precisely regulating interfacial properties. Summary of the Invention

[0004] The present invention provides a two-dimensional heterostructure pyrophosphate / carbon nanocomposite microwave absorbing material, its preparation method and application. The present invention realizes the in-situ construction of a two-dimensional heterostructure in a phosphate MOF matrix by a simple high-temperature pyrolysis method, and regulates the interfacial polarization intensity by changing the type of metal ions, thereby improving the electromagnetic wave absorption performance.

[0005] Technical Solution: A preparation method of a two-dimensional heterostructure pyrophosphate / carbon nanocomposite microwave absorbing material of the present invention includes the following steps: S1. Prepare a precursor phosphate MOF by a solvothermal method; S2. Perform high-temperature pyrolysis treatment on the phosphate MOF obtained in S1 to obtain a two-dimensional heterostructure pyrophosphate / carbon nanocomposite microwave absorbing material.

[0006] Further, in S2, the high-temperature pyrolysis treatment of the phosphate MOF is to heat the phosphate MOF from room temperature to 700-900 °C, keep it warm for 1-3 h, and the heating rate is 5-15 °C / min.

[0007] Further, in S2, during the high-temperature pyrolysis treatment, the sintering atmosphere is a flowing inert gas environment.

[0008] Further, S1 specifically includes: S1.1: Add the phosphoric acid ligand and the metal salt into the organic solvent and stir evenly.

[0009] S1.2: Transfer the mixed solution into a reaction kettle, heat it to 150 - 180 °C and keep it warm for 12 - 36 h to obtain the product phosphate MOF. S1.3: Wash the product multiple times to remove impurities, and then dry it.

[0010] Further, in S1.1, the phosphoric acid ligand is an organic phosphoric acid, and the metal salt is a nitrate or a chloride; the molar ratio of the phosphoric acid ligand to the metal salt is 1:1 - 2; the molar volume ratio of the phosphoric acid ligand, the metal salt, and the organic solvent is 1 mmol:1 - 2 mmol:50 - 80 ml.

[0011] Preferably, the phosphoric acid ligand is phenylphosphonic acid; the metal salt is a nitrate or a chloride of nickel, iron, cobalt, or zinc; the organic solvent is N,N-dimethylformamide.

[0012] Further, in S1.2, the reaction kettle is a stainless steel reaction kettle with a polytetrafluoroethylene lining.

[0013] Further, in S1.3, the washing solvent is methanol or ethanol; the drying condition is vacuum drying, and the drying temperature is 50 - 80 °C.

[0014] The beneficial effects are as follows: Compared with the traditional composite construction of two-dimensional heterostructures, the in-situ construction of two-dimensional heterostructures in the present invention has the advantages of simple and easy operation, energy conservation and environmental protection, and safety and controllability. Compared with traditional composites, the in-situ construction of two-dimensional heterostructures in the present invention can achieve uniform surface coating.

[0015] The present invention synthesizes a material with a heterostructure through a one-step method. The process is simple, efficient, and significantly reduces the production process and time. Meanwhile, in-situ construction can reduce interface defects, enhance the electron coupling between components, and further enhance the electromagnetic wave absorption performance. The nano-composite wave-absorbing material prepared by the present invention is a phosphate metal-organic framework (MOF) that obtains a heterojunction formed by pyrophosphate and carbon after high-temperature pyrolysis. Due to the abundant reaction nodes in the phosphate MOF aggregate and its high reaction activity, a pyrophosphate / carbon interface can be formed through a one-step high-temperature pyrolysis method. The two-dimensional layered structure and large specific surface area of the pyrophosphate / carbon interface promote the separation of charges in the electromagnetic field, thereby improving the polarization loss of the material. In addition, by changing the types of metal ions, the regulation of loss characteristics is achieved, and thus the flexible regulation of electromagnetic wave absorption performance is realized. The prepared two-dimensional heterostructure pyrophosphate / carbon nano-composite wave-absorbing material exhibits excellent electromagnetic wave absorption performance.

[0016] 3) The pyrophosphate / carbon nano-composite wave-absorbing material prepared by the present invention has the characteristics of low cost and good wave-absorbing performance, and can be used as a wave-absorbing agent for electromagnetic wave absorption. The electromagnetic parameters were tested by a network vector analyzer to calculate the wave-absorbing performance. When the matching thickness of the Fe2(P2O7) / C nano-composite material is 3.49 mm, the effective absorption bandwidth can reach 7.06 GHz, showing good application prospects in the absorption of high-frequency electromagnetic waves. Description of the Drawings

[0017] Figure 1 X-ray diffraction pattern of the pyrophosphate / carbon nano-materials prepared in Examples 1-4.

[0018] Figure 2 Transmission electron microscope image of Zn2(P2O7) / C prepared in Example 1.

[0019] Figure 3 Reflection loss diagram of Zn2(P2O7) / C prepared in Example 1 in the frequency range of 2-18 GHz; Figure 4 Transmission electron microscope image of Ni2(P2O7) / C prepared in Example 2.

[0020] Figure 5 Reflection loss diagram of Ni2(P2O7) / C prepared in Example 2 in the frequency range of 2-18 GHz.

[0021] Figure 6 Transmission electron microscope image of Co2(P2O7) / C prepared in Example 3.

[0022] Figure 7 Reflection loss diagram of Co2(P2O7) / C prepared in Example 3 in the frequency range of 2-18 GHz, Figure 8 Transmission electron microscope image of Fe(P2O7) / C prepared in Example 4.

[0023] Figure 9 Reflection loss graph of Fe(P2O7) / C prepared in Example 4 in the frequency range of 2 - 18 GHz.

[0024] Figure 10 Comparison graph of reflection loss values of pyrophosphate / carbon nanomaterials prepared in Examples 1 - 4. Detailed implementation mode

[0025] The technical solution of the present invention will be described in detail below through examples, but the protection scope of the present invention is not limited to the described examples.

[0026] Example 1 (1) A two-dimensional heterostructure Zn2(P2O7) / C nano composite microwave absorbing material, the preparation method includes the following steps: (2) Preparation of phosphate MOF-Zn: Weigh 1 mmol of phenylphosphonic acid and 1 mmol of zinc nitrate powder and add them to 60 ml of N,N-dimethylformamide solvent. After stirring evenly, transfer the mixed solution into a stainless steel reaction kettle with a 100 ml polytetrafluoroethylene liner, heat to 160 °C and react for 24 h. Wash the obtained product with ethanol multiple times and vacuum dry it at 60 °C to obtain phosphate MOF-Zn.

[0027] Preparation of Zn2(P2O7) / C: Place the phosphate MOF-Zn in a flowing argon atmosphere, heat to 800 °C for high-temperature pyrolysis, with a heating rate of 5 °C / min and a holding time of 2 h, and then naturally cool to room temperature to obtain the two-dimensional heterostructure Zn2(P2O7) / C nano composite microwave absorbing material.

[0028] Perform X-ray diffraction measurement and transmission electron microscope scanning measurement on Zn2(P2O7) / C prepared in Example 1. The results are as Figures 1 - 3 shown. It can be seen from Figure 1 that there are obvious Zn2(P2O7) diffraction peaks. Figure 2 Scanning electron microscope image of Zn2(P2O7) / C prepared in Example 1. The unique two-dimensional layered structure of the Zn2(P2O7) / C nano material can be seen in the left figure, and a large number of interfaces between Zn2(P2O7) and C can be seen in the crystal structure of Zn2(P2O7) / C in the right figure. Figure 3The reflection loss diagram of Zn2(P2O7) / C prepared in Example 1 within the frequency range of 2 - 18 GHz can be seen. The wave absorption performance of Zn2(P2O7) / C shows that under the condition of a matching thickness of 2.44 mm, the effective absorption bandwidth reaches 6.08 GHz (11.65 - 17.73 GHz).

[0029] Example 2 A two-dimensional heterostructure Ni2(P2O7) / C nanocomposite wave-absorbing material, the preparation method includes the following steps: (1) Preparation of phosphate MOF-Ni: Weigh 1 mmol of phenylphosphonic acid and 1 mmol of nickel nitrate powder and add them to 60 ml of N,N-dimethylformamide solvent. After stirring evenly, transfer the mixed solution into a stainless steel reaction kettle with a 100 ml polytetrafluoroethylene liner, heat to 160 °C and react for 24 h. Wash the obtained product with ethanol multiple times and vacuum dry it at 60 °C to obtain phosphate MOF-Ni; (2) Preparation of Ni2(P2O7) / C. Place the phosphate MOF-Ni in a flowing argon atmosphere, heat to 800 °C for high-temperature pyrolysis, with a heating rate of 5 °C / min and a holding time of 2 h, and then naturally cool to room temperature to obtain the two-dimensional heterostructure Ni2(P2O7) / C nanocomposite wave-absorbing material.

[0030] Perform X-ray diffraction measurement and transmission electron microscope scanning measurement on Ni2(P2O7) / C prepared in Example 2. The results are as Figure 1 and Figures 4 - 5 shown. It can be seen from Figure 1 that there are obvious Ni2(P2O7) diffraction peaks. Figure 4 The scanning electron microscope image of Ni2(P2O7) / C prepared in Example 2. The unique two-dimensional layered structure of the Ni2(P2O7) / C nanomaterial can be seen in the left figure, and a large number of interfaces between Ni2(P2O7) and C can be seen in the crystal structure of Ni2(P2O7) / C in the right figure. Figure 5 The reflection loss diagram of Ni2(P2O7) / C prepared in Example 2 within the frequency range of 2 - 18 GHz can be seen. The wave absorption performance of Ni2(P2O7) / C shows that under the condition of a matching thickness of 3.69 mm, the effective absorption bandwidth is 5.01 GHz (12.97 - 17.98 GHz).

[0031] Example 3 A two-dimensional heterostructure Co2(P2O7) / C nanocomposite wave-absorbing material, the preparation method includes the following steps: (1) Preparation of phosphate MOF-Co: Weigh 1 mmol of phenylphosphonic acid and 1 mmol of cobalt nitrate powder and add them to 60 ml of N,N-dimethylformamide solvent. After stirring evenly, transfer the mixed solution into a stainless-steel autoclave with a 100 ml polytetrafluoroethylene liner, heat to 160 °C and react for 24 h. Wash the obtained product with ethanol multiple times and dry it under vacuum at 60 °C to obtain phosphate MOF-Co; (2) Preparation of Co2(P2O7) / C: Place the phosphate MOF-Co in a flowing argon atmosphere, heat to 800 °C for high-temperature pyrolysis, with a heating rate of 5 °C / min and a holding time of 2 h, and then naturally cool to room temperature to obtain the two-dimensional heterostructure Co2(P2O7) / C nano-composite microwave absorption material.

[0032] Perform X-ray diffraction measurement and transmission electron microscopy scanning measurement on the Co2(P2O7) / C prepared in Example 3. The results are as Figure 1 and Figures 6 - 7 shown. It can be seen from Figure 1 that there are obvious Co2(P2O7) diffraction peaks. Figure 6 is the scanning electron microscopy image of the Co2(P2O7) / C prepared in Example 3. It can be seen from the left figure that the Co2(P2O7) / C nano-material has a unique two-dimensional layered structure, and it can be seen from the right figure that there are a large number of interfaces between Ni2(P2O7) and C in the Co2(P2O7) / C crystal structure. Figure 7 is the reflection loss diagram of the Co2(P2O7) / C prepared in Example 3 in the frequency range of 2 - 18 GHz. It can be seen that the microwave absorption performance of Co2(P2O7) / C, under the condition of a matching thickness of 3.55 mm, the effective absorption bandwidth is 4.18 GHz (13.82 - 18 GHz).

[0033] Example 4 A two-dimensional heterostructure Fe(P2O7) / C nano-composite microwave absorption material, the preparation method includes the following steps: (1) Preparation of phosphate MOF-Fe: Weigh 1 mmol of phenylphosphonic acid and 1 mmol of iron nitrate powder and add them to 60 ml of N,N-dimethylformamide solvent. After stirring evenly, transfer the mixed solution into a stainless-steel autoclave with a 100 ml polytetrafluoroethylene liner, heat to 160 °C and react for 24 h. Wash the obtained product with ethanol multiple times and dry it under vacuum at 60 °C to obtain phosphate MOF-Fe; (2) Preparation of Fe(P2O7) / C: Place the phosphate MOF-Fe in a flowing argon atmosphere, heat it to 800 °C for high-temperature pyrolysis, with a heating rate of 5 °C / min and a holding time of 2 h, and then naturally cool it to room temperature to obtain the two-dimensional heterostructure Fe(P2O7) / C nanocomposite microwave absorption material.

[0034] Perform X-ray diffraction measurement, transmission electron microscopy scanning measurement and electromagnetic wave absorption performance calculation on the Fe(P2O7) / C prepared in Example 4. The results are as Figure 1 and Figures 8 - 9 shown: It can be seen from Figure 1 that there are obvious diffraction peaks of Fe(P2O7). Figure 8 is the scanning electron microscopy image of the Fe(P2O7) / C prepared in Example 4. The unique two-dimensional layered structure of the Fe(P2O7) / C nanomaterial can be seen in the left figure, and a large number of interfaces between Fe(P2O7) and C can be seen in the crystal structure of Fe(P2O7) / C in the right figure. Figure 9 is the reflection loss graph of the Fe2(P2O7) / C prepared in Example 4 in the frequency range of 2 - 18 GHz. It can be seen that the microwave absorption performance of Fe2(P2O7) / C reaches an effective absorption bandwidth of 7.06 GHz (10.75 - 17.81 GHz) under the condition of a matching thickness of 3.49 mm.

[0035] The comparison of the reflection loss values of the pyrophosphate / carbon nanomaterials prepared in Examples 1 - 4 is as Figure 10 shown.

[0036] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as a limitation of the present invention itself. Various changes can be made to it in form and detail without departing from the spirit and scope of the present invention.

Claims

1. A preparation method of a pyrophosphate / carbon nanocomposite microwave absorbing material with a two-dimensional heterostructure, characterized in that, It includes the following steps: S1. Prepare a precursor phosphate MOF by solvothermal method; S2. Perform high-temperature pyrolysis treatment on the phosphate MOF obtained in S1 to obtain a pyrophosphate / carbon nanocomposite absorbing material with a two-dimensional heterostructure; The conditions for high-temperature pyrolysis treatment are: heat the phosphate MOF from room temperature to 700-900 °C in a flowing inert gas environment and keep it for 1-3 h, and the heating rate is 5-15 °C / min.

2. The preparation method according to claim 1, characterized in that, Specifically, S1 is as follows: S1.

1. Add a phosphoric acid ligand and a metal salt to an organic solvent and stir evenly; S1.

2. Transfer the mixed solution into a reaction kettle, heat it to 150-180 °C and keep it for 12-36 h to obtain the product phosphate MOF; S1.

3. Wash the product multiple times to remove impurities, and then dry it.

3. According to the preparation method described in claim 2, characterized in that In S1.1, the phosphoric acid ligand is an organic phosphoric acid, and the metal salt is a nitrate or a chloride; the molar ratio of the phosphoric acid ligand to the metal salt is 1:1-2; In S1.3, the drying temperature is 50-80 °C.

4. The preparation method according to claim 3, characterized in that, In S1.1, the phosphoric acid ligand is phenylphosphonic acid; the metal salt is a nitrate or a chloride of nitrate, iron, cobalt, or zinc; the organic solvent is N,N-dimethylformamide; In S1.3, the washing solvent is methanol or ethanol, and the drying condition is vacuum drying.

5. The preparation method according to claim 1, wherein, In S2, the inert gas is argon.

6. A two-dimensional heterostructure pyrophosphate / carbon nanocomposite microwave absorbing material, characterized in that, The pyrophosphate / carbon nanocomposite absorbing material with a two-dimensional heterostructure is prepared by the preparation method described in any one of claims 1-5.

7. Use of the two-dimensional heterostructure pyrophosphate / carbon nanocomposite microwave absorbing material according to claim 6, characterized in that, The pyrophosphate / carbon nanocomposite absorbing material with a two-dimensional heterostructure is used for electromagnetic wave absorption.

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