A two-dimensional heterostructured pyrophosphate / carbon nanocomposite absorbing material and its preparation method and application

Abstract

The present invention provides a two-dimensional heterostructured pyrophosphate / carbon nanocomposite absorbing material, its preparation method, and application, belonging to the field of nanomaterials. The present invention achieves in situ construction of a pyrophosphate-carbon heterointerface by pyrolyzing a phosphate metal ion framework (MOF) at high temperature, and further modulates polarization loss by varying the type of metal ions, thereby improving electromagnetic wave absorption performance. The two-dimensional heterostructured pyrophosphate / carbon nanocomposite absorbing material prepared by the present invention exhibits excellent electromagnetic wave absorption performance. The pyrophosphate / carbon nanocomposite absorbing material is lightweight, low-cost, and has excellent absorption performance, making it suitable for use as an absorbent.

Description

Technical Field

[0001] The present invention belongs to the field of nanomaterials, and in particular relates to a two-dimensional heterostructured pyrophosphate / carbon nanocomposite wave-absorbing material, a preparation method thereof, and applications thereof. Background Art

[0002] With the rapid development of electronic information technology, the increasing prevalence of wireless communications, the Internet of Things, and technologies such as 5G / 6G, the application of electromagnetic waves has become pervasive in every aspect of modern society. However, electromagnetic interference and radiation pollution caused by electromagnetic devices are becoming increasingly serious, posing a threat not only to the normal operation of electronic equipment but also to potential risks to human health. To address this challenge, electromagnetic compatibility technology has emerged. The key lies in the use of electromagnetic shielding or absorbing materials to suppress the reflection and propagation of electromagnetic waves. The development of high-efficiency electromagnetic wave absorbing materials has become a key approach to solving this problem.

[0003] Heterostructures, through multi-component synergy, enhanced interfacial polarization, and optimized structural design, have become a core development direction for electromagnetic wave absorbing materials. However, their widespread application is still limited by bandwidth-thickness balance, preparation costs, and insufficient theoretical research. Laboratory preparation methods (such as freeze-drying and high-temperature carbonization) are costly and difficult to mass-produce. For example, the synthesis of rGO / CFs involves a multi-step freeze-drying and carbonization process. 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 overcome these bottlenecks by precisely controlling interfacial properties. Summary of the Invention

[0004] The present invention provides a two-dimensional heterostructured pyrophosphate / carbon nanocomposite absorber, its preparation method, and application. This invention utilizes a simple high-temperature pyrolysis method to achieve in-situ construction of the two-dimensional heterostructure within a phosphate MOF matrix. By varying the type of metal ions, the interfacial polarization intensity is modulated, thereby improving electromagnetic wave absorption performance.

[0005] Technical solution: The present invention provides a method for preparing a two-dimensional heterostructured pyrophosphate / carbon nanocomposite absorbing material, comprising the following steps:

[0006] S1. Preparation of precursor phosphate MOF by solvothermal method;

[0007] S2. The phosphate MOF prepared in S1 is subjected to high-temperature pyrolysis treatment to obtain a pyrophosphate / carbon nanocomposite absorbing material with a two-dimensional heterogeneous structure.

[0008] Furthermore, in S2, the high-temperature pyrolysis treatment of the phosphate MOF is to heat the phosphate MOF from room temperature to 700~900 °C and keep it for 1-3 h, with a heating rate of 5~15 °C / min.

[0009] Furthermore, in S2, during the high-temperature pyrolysis treatment, the sintering atmosphere is a circulating inert gas environment.

[0010] Furthermore, S1 is specifically:

[0011] S1.1. Add the phosphate ligand and metal salt into the organic solvent and stir evenly.

[0012] S1.2. Transfer the mixed solution to a reactor and heat to 150-180 °C for 12-36 h to obtain the phosphate MOF product.

[0013] S1.3. The product is washed multiple times to remove impurities and then dried.

[0014] Furthermore, in S1.1, the phosphate ligand is an organic phosphate, and the metal salt is a nitrate or a chloride; the molar ratio of the phosphate ligand to the metal salt is 1:1~2; and the molar volume ratio of the phosphate ligand, the metal salt, and the organic solvent is 1mmol:1~2mmol:50~80ml.

[0015] Preferably, the phosphate ligand is phenylphosphonic acid; the metal salt is nitrate or chloride of nitric acid, iron, cobalt, or zinc; and the organic solvent is N,N-dimethylformamide.

[0016] Furthermore, in S1.2, the reactor is a stainless steel reactor lined with polytetrafluoroethylene.

[0017] Furthermore, in S1.3, the washing solvent is methanol or ethanol; the drying condition is vacuum drying, and the drying temperature is 50-80 °C.

[0018] The beneficial effects are as follows:

[0019] Compared to traditional composite 2D heterostructures, the in-situ 2D heterostructure construction method of the present invention offers advantages such as simplicity, ease of operation, energy conservation, environmental protection, safety, and controllability. Compared to traditional composite methods, the in-situ 2D heterostructure construction method of the present invention enables uniform surface coating.

[0020] This invention synthesizes heterostructured materials through a one-step process. The process is simple and efficient, significantly reducing production process and time. Furthermore, in-situ construction reduces interfacial defects, enhances electronic coupling between components, and further improves electromagnetic wave absorption performance. The nanocomposite absorber prepared by this invention is a phosphate metal organic framework (MOF) that undergoes high-temperature pyrolysis to obtain a heterogeneous interface formed by pyrophosphate and carbon. Due to the abundant reactive nodes within the phosphate-MOF framework and its high reactivity, the pyrophosphate / carbon interface can be formed in a single step through high-temperature pyrolysis. The two-dimensional layered structure and large specific surface area of ​​the pyrophosphate / carbon interface promote charge separation in the electromagnetic field, thereby improving the material's polarization loss. Furthermore, by varying the type of metal ions, the loss characteristics can be manipulated, thereby enabling flexible control of electromagnetic wave absorption performance. The prepared two-dimensional heterostructured pyrophosphate / carbon nanocomposite absorber exhibits excellent electromagnetic wave absorption performance.

[0021] 3) The pyrophosphate / carbon nanocomposite absorber prepared by this invention features low cost and excellent absorption properties, making it suitable for use as an absorber for electromagnetic wave absorption. Electromagnetic parameters were measured using a network vector analyzer, and the absorption performance was calculated. When the Fe2(P2O7) / C nanocomposite material had a matching thickness of 3.49 mm, the effective absorption bandwidth reached 7.06 GHz, demonstrating promising application prospects in high-frequency electromagnetic wave absorption. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The X-ray diffraction patterns of the pyrophosphate / carbon nanomaterials prepared in Examples 1-4 are shown.

[0023] Figure 2 This is a transmission electron microscope image of Zn2(P2O7) / C prepared in Example 1.

[0024] Figure 3 Graph showing the reflection loss of Zn2(P2O7) / C prepared in Example 1 in the frequency range of 2-18 GHz;

[0025] Figure 4 This is a transmission electron microscope image of Ni2(P2O7) / C prepared in Example 2.

[0026] Figure 5 This is the reflection loss diagram of Ni2(P2O7) / C prepared in Example 2 in the frequency range of 2-18 GHz.

[0027] Figure 6 This is a transmission electron microscope image of Co2(P2O7) / C prepared in Example 3.

[0028] Figure 7 This is the reflection loss diagram of Co2(P2O7) / C prepared in Example 3 in the frequency range of 2-18 GHz.

[0029] Figure 8 This is a transmission electron microscope image of Fe(P2O7) / C prepared in Example 4.

[0030] Figure 9 This is the reflection loss diagram of Fe(P2O7) / C prepared in Example 4 in the frequency range of 2-18 GHz.

[0031] Figure 10 2 is a comparison chart of the reflection loss values ​​of the pyrophosphate / carbon nanomaterials prepared in Examples 1-4. DETAILED DESCRIPTION

[0032] The technical solutions of the present invention are described in detail below through examples, but the protection scope of the present invention is not limited to the examples.

[0033] Example 1

[0034] (1) A two-dimensional heterostructure Zn2(P2O7) / C nanocomposite absorbing material, the preparation method of which comprises the following steps:

[0035] (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, the mixed solution is transferred to a stainless steel reactor lined with 100 ml of polytetrafluoroethylene and heated to 160 °C for 24 h. The obtained product is washed with ethanol several times and dried in vacuo at 60 °C to obtain phosphate MOF-Zn.

[0036] Preparation of Zn2(P2O7) / C: Phosphate MOF-Zn was placed in a circulating argon atmosphere and heated to 800 °C for high-temperature pyrolysis at a heating rate of 5 °C / min and a holding time of 2 h. It was then naturally cooled to room temperature to obtain the two-dimensional heterostructured Zn2(P2O7) / C nanocomposite absorbing material.

[0037] The Zn2(P2O7) / C prepared in Example 1 was subjected to X-ray diffraction and transmission electron microscopy measurements. The results are as follows: Figures 1-3 As shown. Figure 1 Obvious Zn2(P2O7) diffraction peaks can be seen in the figure. Figure 2 This is a scanning electron microscope image of Zn2(P2O7) / C prepared in Example 1. The left image shows the unique two-dimensional layered structure of the Zn2(P2O7) / C nanomaterial, and the right image shows the presence of a large number of interfaces between Zn2(P2O7) and C in the Zn2(P2O7) / C crystal structure. Figure 3This is a reflection loss diagram of Zn2(P2O7) / C prepared in Example 1 in the frequency range of 2-18 GHz. It can be seen that the absorption performance of Zn2(P2O7) / C is good. Under the condition of matching thickness of 2.44 mm, the effective absorption bandwidth reaches 6.08 GHz (11.65~17.73 GHz).

[0038] Example 2

[0039] A two-dimensional heterostructured Ni2(P2O7) / C nanocomposite absorbing material, the preparation method of which comprises the following steps:

[0040] (1) Preparation of Ni-phosphate MOF: 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, the mixed solution is transferred to a stainless steel reactor lined with 100 ml of polytetrafluoroethylene and heated to 160 °C for 24 h. The obtained product is washed with ethanol several times and dried in vacuo at 60 °C to obtain Ni-phosphate MOF.

[0041] (2) Preparation of Ni2(P2O7) / C: The phosphate MOF-Ni was placed in a circulating argon atmosphere, heated to 800 °C for high-temperature pyrolysis at a heating rate of 5 °C / min and a holding time of 2 h, and then naturally cooled to room temperature to obtain the two-dimensional heterostructure Ni2(P2O7) / C nanocomposite absorbing material.

[0042] The Ni2(P2O7) / C prepared in Example 2 was subjected to X-ray diffraction and transmission electron microscopy measurements. The results are as follows: Figure 1 and Figures 4 and 5 As shown. Figure 1 Obvious Ni2(P2O7) diffraction peaks can be seen in the figure. Figure 4 This is a scanning electron microscope image of Ni2(P2O7) / C prepared in Example 2. The left image shows the unique two-dimensional layered structure of Ni2(P2O7) / C nanomaterial, and the right image shows the presence of a large number of Ni2(P2O7) and C interfaces in the Ni2(P2O7) / C crystal structure. Figure 5 This is the reflection loss diagram of Ni2(P2O7) / C prepared in Example 2 in the frequency range of 2-18 GHz. It can be seen that the absorption performance of Ni2(P2O7) / C is good. Under the condition of matching thickness of 3.69 mm, the effective absorption bandwidth is 5.01 GHz (12.97~17.98 GHz).

[0043] Example 3

[0044] A two-dimensional heterostructured Co2(P2O7) / C nanocomposite absorbing material, the preparation method of which comprises the following steps:

[0045] (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, the mixed solution is transferred to a stainless steel reactor lined with 100 ml of polytetrafluoroethylene and heated to 160 °C for 24 h. The obtained product is washed with ethanol several times and dried in vacuo at 60 °C to obtain phosphate MOF-Co.

[0046] (2) Preparation of Co2(P2O7) / C: The phosphate MOF-Co was placed in a circulating argon atmosphere and heated to 800 °C for high-temperature pyrolysis at a heating rate of 5 °C / min and a holding time of 2 h. It was then naturally cooled to room temperature to obtain the two-dimensional heterostructure Co2(P2O7) / C nanocomposite absorbing material.

[0047] The Co2(P2O7) / C prepared in Example 3 was subjected to X-ray diffraction and transmission electron microscopy measurements. The results are as follows: Figure 1 and Figures 6 and 7 As shown. Figure 1 Obvious Co2(P2O7) diffraction peaks can be seen in the figure. Figure 6 This is a scanning electron microscope image of Co2(P2O7) / C prepared in Example 3. The left image shows the unique two-dimensional layered structure of the Co2(P2O7) / C nanomaterial, and the right image shows the presence of a large number of Ni2(P2O7) and C interfaces in the Co2(P2O7) / C crystal structure. Figure 7 This is the reflection loss diagram of Co2(P2O7) / C prepared in Example 3 in the frequency range of 2-18 GHz. It can be seen that the absorption performance of Co2(P2O7) / C is good. Under the condition of matching thickness of 3.55 mm, the effective absorption bandwidth is 4.18 GHz (13.82~18 GHz).

[0048] Example 4

[0049] A two-dimensional heterostructured Fe(P2O7) / C nanocomposite absorbing material, the preparation method of which comprises the following steps:

[0050] (1) Preparation of phosphate MOF-Fe: Weigh 1 mmol of phenylphosphonic acid and 1 mmol of ferric nitrate powder and add them to 60 ml of N,N-dimethylformamide solvent. After stirring evenly, the mixed solution is transferred to a stainless steel reactor lined with 100 ml of polytetrafluoroethylene and heated to 160 °C for 24 h. The obtained product is washed with ethanol several times and dried in vacuo at 60 °C to obtain phosphate MOF-Fe.

[0051] (2) Preparation of Fe(P2O7) / C: The phosphate MOF-Fe was placed in a circulating argon atmosphere and heated to 800 °C for high-temperature pyrolysis at a heating rate of 5 °C / min and a holding time of 2 h. It was then naturally cooled to room temperature to obtain the two-dimensional heterostructured Fe(P2O7) / C nanocomposite absorbing material.

[0052] The Fe(P2O7) / C prepared in Example 4 was subjected to X-ray diffraction measurement, transmission electron microscopy scanning measurement and electromagnetic wave absorption performance calculation. The results are as follows Figure 1 and Figures 8 and 9 Shown: From Figure 1 Obvious Fe(P2O7) diffraction peaks can be seen in the figure. Figure 8 This is a scanning electron microscope image of Fe(P2O7) / C prepared in Example 4. The left image shows the unique two-dimensional layered structure of the Fe(P2O7) / C nanomaterial, and the right image shows the presence of a large number of Fe(P2O7) and C interfaces in the Fe(P2O7) / C crystal structure. Figure 9 This is a reflection loss diagram of Fe2(P2O7) / C prepared in Example 4 in the frequency range of 2-18 GHz. It can be seen that the absorption performance of Fe2(P2O7) / C is good. Under the condition of matching thickness of 3.49 mm, the effective absorption bandwidth reaches 7.06 GHz (10.75~17.81 GHz).

[0053] Comparison of reflection loss values ​​of pyrophosphate / carbon nanomaterials prepared in Examples 1-4 Figure 10 shown.

[0054] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes may be made to the form and details without departing from the spirit and scope of the present invention.

Claims

1. A method for preparing a two-dimensional heterostructured pyrophosphate / carbon nanocomposite absorbing material, characterized in that: The steps include: S1. Preparation of precursor phosphate MOF by solvothermal method; S1.

1. Add the phosphate ligand and metal salt to the organic solvent and stir evenly; In S1.1, the phosphate ligand is phenylphosphonic acid; the metal salt is a nitrate or chloride of nickel, iron, cobalt, or zinc; and the organic solvent is N,N-dimethylformamide; S1.

2. Transfer the mixed solution to a reactor and heat to 150-180 °C for 12-36 h to obtain the phosphate MOF product. S1.3, washing the product several times to remove impurities, and then drying; S2, subjecting the phosphate MOF prepared in S1 to high-temperature pyrolysis treatment to obtain a pyrophosphate / carbon nanocomposite absorbing material with a two-dimensional heterostructure; The high-temperature pyrolysis treatment conditions are as follows: the phosphate MOF is heated from room temperature to 700-900°C in a circulating inert gas environment and kept at this temperature for 1-3 hours, with a heating rate of 5-15°C / min.

2. The preparation method according to claim 1, characterized in that In S1.1, the molar ratio of phosphate ligand to metal salt is 1:1~2; In S1.3, the drying temperature is 50~80 °C.

3. The preparation method according to claim 2, characterized in that In S1.3, the washing solvent is methanol or ethanol, and the drying condition is vacuum drying.

4. The preparation method according to claim 1, characterized in that In S2, the inert gas is argon.

5. A two-dimensional heterostructured pyrophosphate / carbon nanocomposite absorbing material, characterized in that: The two-dimensional heterostructured pyrophosphate / carbon nanocomposite absorbing material is prepared according to the preparation method according to any one of claims 1 to 4.

6. Use of the two-dimensional heterostructured pyrophosphate / carbon nanocomposite absorbing material according to claim 5, characterized in that: The two-dimensional heterostructured pyrophosphate / carbon nanocomposite wave absorbing material is used for electromagnetic wave absorption.

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