Fe3O4-modified phosphorus-doped carbon-based porous wave-absorbing material and preparation method thereof

Abstract

The invention discloses a preparation method of a Fe3O4 modified phosphorus-doped carbon-based porous wave-absorbing material constructed on the basis of a multi-component strategy. The preparation method comprises the following steps: firstly, preparing a phosphorus-doped carbon-based porous nano material through a freeze-drying method and a sacrificial template method, then obtaining a Fe3O4 intermediate through oil bath, and finally reducing for 6 hours in an Ar atmosphere to obtain the Fe3O4-modified phosphorus-doped carbon-based porous wave-absorbing material, namely Fe3O4 (at) P-NCP. Based on a good magnetic loss mechanism of the material, a synergistic effect of dielectric loss and magnetic loss is provided for electromagnetic wave absorption. And meanwhile, the porous structure ensures that incident electromagnetic waves can form multiple reflections in the porous structure. The material has the advantages of good microwave absorption performance, thin matching thickness, wide effective absorption frequency band and the like. A good foundation is provided for development of porous materials, and a good design thought is provided for preparation of electromagnetic wave absorbing materials. The good microwave absorption performance of the material can play a good role in electromagnetic radiation and pollution, and the material has a wide application prospect.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of nanocomposite materials and electromagnetic wave absorption technology, and specifically relates to Fe 3 O 4 Preparation and application of modified phosphorus-doped carbon-based porous absorbing materials. Background Art

[0002] The rapid innovation of modern electronic technology has pushed society into an era of comprehensive informatization, and electronic equipment is evolving towards high integration and miniaturization. While electronic products have significantly improved the quality of human life, the problem of electromagnetic pollution has become increasingly prominent. The development of high-performance electromagnetic wave absorption materials has great research value in ensuring the stable operation of precision equipment and maintaining the safety of the human biomagnetic field. Such materials can effectively reduce the reflection and transmission intensity of electromagnetic waves by converting incident electromagnetic waves into other energy forms such as heat energy.

[0003] Porous carbon-based materials have attracted much attention due to their unique three-dimensional multi-level pore system: the high specific surface area, rich pore structure and intrinsic defect characteristics construct a gradient impedance matching system. The multi-scale pores not only extend the propagation path of electromagnetic waves, but also improve the energy dissipation efficiency through multiple reflection-scattering effects. This hierarchical porous architecture enhances the wave absorption performance in three aspects: first, the fractal pore network promotes the multi-level scattering of electromagnetic waves; second, the interconnected conductive network enhances the conductivity loss mechanism; finally, the high-density gas-solid interface induces the interface polarization effect. It is worth noting that pure carbon-based materials have intrinsic defects - impedance mismatch caused by excessive conductivity and a single dielectric loss mechanism limit their practical applications.

[0004] The current research focus is on constructing a multi-component heterogeneous composite system and achieving coordinated regulation of electromagnetic parameters by introducing magnetic components. This strategy has dual advantages: it inherits the dielectric loss characteristics of carbon materials, integrates the magnetic loss mechanism of magnetic materials, and solves the impedance matching problem through component optimization. Magnetic particles have become electromagnetic functional materials with great development potential due to their good chemical stability and adjustable electromagnetic parameters. The interfacial polarization effect produced by heterogeneous interface engineering (including component interfaces, grain boundaries and phase interfaces) provides a new dimension for improving the electromagnetic response of materials.

[0005] Research practice shows that by precisely controlling the hierarchical structure of the porous carbon matrix and constructing a magnetic-dielectric synergistic system, the impedance matching characteristics and multi-mode loss mechanism of the material can be simultaneously optimized. This material design concept has opened up a new path for the development of broadband and highly absorbing electromagnetic protection materials, and has important strategic significance for solving the electromagnetic pollution problems faced by the information society. Summary of the invention

[0006] The present invention aims to provide Fe 3 O4 A method for preparing a modified phosphorus-doped carbon-based porous wave absorbing material, the specific invention contents are as follows:

[0007] 1. Using phosphorus-doped carbon-based porous nanomaterials as carriers, the Fe2O3 nanoparticles grown in situ on phosphorus-doped carbon-based porous materials were obtained by freeze drying, sacrificial template method, oil bath method and Ar reduction method. 3 O 4 The microwave absorbing material composed of nanoparticles is prepared by the following method:

[0008] (1) First, weigh 1.2 mol of sodium chloride and 0.1 mol of citric acid, then weigh 0.0375 mol of sodium hypophosphite, add 100 ml of deionized water to prepare a solution, freeze the clear solution and place it in a freeze dryer for low-temperature freeze drying, and after drying to anhydrous state, finely grind the sample to obtain a white powder.

[0009] (2) The white powder obtained in step (1) is placed in a tube furnace, heated to 750°C at a heating rate of 5°C / min, taken out after being kept warm for 2 hours, and placed in a container filled with deionized water to soak to wash away the NaCl template, and finally filtered and dried to obtain a phosphorus-doped carbon-based porous nanomaterial.

[0010] (3) Weigh 0.1 g of the phosphorus-doped carbon-based porous material prepared in step (2). Then weigh 0.1 g of urea and 0.3 g of ferric nitrate nonahydrate, add 100 ml of deionized water to prepare a uniform solution, and place it in a conical flask. Place the conical flask containing the liquid in an oil bath and keep it warm at 120° C. for 6 hours.

[0011] (4) The product of step (3) was placed in a tube furnace, heated to a set temperature in an Ar atmosphere, and then kept warm for 2 hours and cooled to room temperature to obtain the Fe 3 O 4 Modified phosphorus-doped carbon-based porous absorber materials.

[0012] 2.Fe 3 O 4 Modified phosphorus-doped carbon-based porous absorber (Fe 3 O 4 @P-NCP) has a minimum reflection loss of -53.56dB at a thickness of only 1.91mm, and exhibits excellent electromagnetic wave absorption properties.

[0013] The Fe based on multi-component strategy disclosed in the present invention 3 O 4 Compared with the existing technology, the advantages of @P-NCP absorbing material are:

[0014] (1) The porous carbon matrix has a rich three-dimensional porous network structure with interconnected pores. The carbon-based skeleton has excellent electrical conductivity, which enhances the material's ability to propagate electromagnetic waves. It greatly enhances the conduction loss of electromagnetic waves and effectively converts electric and magnetic field energy into heat energy.

[0015] (2) Porous carbon has a very high specific surface area, which means that there are a lot of spaces and sites inside and on the surface for magnetic particles to attach. 3 O 4 The particles provide a good loading platform.

[0016] (3)Fe 3 O 4 It is a ferromagnetic material with high magnetic permeability. It can produce magnetic loss mechanisms such as hysteresis loss, eddy current loss and resonance loss under the alternating electromagnetic field, and convert the energy of electromagnetic waves into other forms of energy such as heat and dissipate it. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The Fe prepared in Example 1 3 O 4 SEM image of modified phosphorus-doped carbon-based porous absorber material.

[0018] Figure 2 The Fe prepared in Example 1 3 O 4 TEM and HETEM images of modified phosphorus-doped carbon-based porous absorbing materials.

[0019] Figure 3 The Fe prepared in Example 1 3 O 4 XRD pattern of modified phosphorus-doped carbon-based porous absorber material.

[0020] Figure 4 The Fe prepared in Example 1 3 O 4 XPS spectrum of modified phosphorus-doped carbon-based porous absorbing material.

[0021] Figure 5 The Fe prepared in Example 1 3 O 4 Reflection loss of modified phosphorus-doped carbon-based porous absorber: (a) dot-line graph, (b) two-dimensional graph, and (c) three-dimensional graph.

[0022] Figure 6 The Fe prepared in Example 1 3 O 4 Modification of phosphorus-doped carbon-based porous absorber (a)Z in / Z 0curve, (b) decay constant. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to specific examples, but these examples do not limit the scope of the present invention in any way.

[0024] Example 1

[0025] The Fe 3 O 4 The preparation method of modified phosphorus-doped carbon-based porous wave absorbing material comprises the following steps:

[0026] (1) Weigh 1.2 mol of sodium chloride, 0.1 mol of citric acid, and then weigh 0.0375 mol of sodium hypophosphite, add 100 ml of deionized water to prepare a solution, freeze the clear solution and place it in a freeze dryer for low-temperature freeze drying, and after drying to anhydrous state, finely grind the sample to obtain a white powder.

[0027] (2) The white powder obtained in step (1) is placed in a tube furnace, heated to 750°C at a heating rate of 5°C / min, taken out after being kept warm for 2 hours, and placed in a container filled with deionized water to soak to wash away the NaCl template, and finally filtered and dried to obtain a phosphorus-doped carbon-based porous nanomaterial.

[0028] (3) Weigh 0.1 g of the phosphorus-doped carbon-based porous material prepared in step (2). Then weigh 0.1 g of urea and 0.3 g of ferric nitrate nonahydrate, add 100 ml of deionized water to prepare a uniform solution, and place it in a conical flask. Place the conical flask containing the liquid in an oil bath and keep it warm at 120° C. for 6 hours.

[0029] (4) placing the product of step (3) in a tube furnace, heating it to a set temperature in an Ar atmosphere, and then cooling it to room temperature for 6 hours to obtain the Fe 3 O 4 Modified phosphorus-doped carbon-based porous absorber materials.

[0030] The Fe 3 O 4 The SEM images of the modified phosphorus-doped carbon-based porous absorber at different magnifications are shown in the attached drawings of the specification. Figure 1 (a), (b). It can be seen that the material has a pore-interlaced structure, and the large geometric surface provides an ideal loading area for active particles. 3 O 4 Nanoparticles are uniformly loaded on the geometric surface. Figure 2 (b) It can be clearly seen that there are lattice fringes with a lattice spacing of 0.485 nm, corresponding to Fe 3 O4 (111) crystal plane. In addition, it can be seen that Fe 3 O 4 Clear boundaries between particles and matrix. Figure 3 The XRD diagram in the figure shows that the characteristic peaks at 18.270°, 30.095°, 35.423°, 37.053°, 43.053°, 53.392°, and 56.944° correspond to Fe 3 O 4 The (111), (220), (311), (222), (400), (422), (511) and (440) crystal planes (PDF#00-019-0629). 3 O 4 Successful preparation of nanoparticles.

[0031] The electromagnetic wave absorption performance test of the product is tested and analyzed by vector network analyzer. The product is mixed with paraffin in a certain proportion to make a coaxial ring with an outer diameter of 7mm, an inner diameter of 3mm, and a thickness of 2mm. The electromagnetic wave absorption performance test is carried out by coaxial measurement method. Figure 5 The microwave absorption performance of the absorbing material. It can be seen that when the thickness is 1.91 mm, the minimum reflection loss value of the material is RL min =-53.56dB; when the thickness is 2.07mm, the maximum effective absorption bandwidth of the material is EAB max =6.08GHz. It shows excellent electromagnetic wave absorption performance. Figure 6 From the electromagnetic parameters, it can be seen that the material exhibits excellent impedance matching performance and has a relatively ideal attenuation constant. This is due to the introduction of magnetic particles, which gives the material strong magnetic loss capacity.

Claims

1. A Fe3O4 modified phosphorus-doped carbon-based porous absorbing material, characterized in that: By freeze drying, sacrificial template method, oil bath method and Ar reduction method, a wave absorbing material composed of Fe3O4 nanoparticles in situ grown on a phosphorus-doped carbon-based porous material is obtained. It is characterized in that it is prepared by the following method: (1) First, weigh 1.2 mol of sodium chloride and 0.1 mol of citric acid, then weigh a certain mass of sodium hypophosphite, add 100 ml of deionized water to prepare a solution, freeze the clear solution and place it in a freeze dryer for low-temperature freeze drying, and after drying to anhydrous state, finely grind the sample to obtain a white powder. (2) The white powder obtained in step (1) is placed in a tube furnace, heated to 750°C at a heating rate of 5°C / min, taken out after being kept warm for 2 hours, and placed in a container filled with deionized water to soak to wash away the NaCl template, and finally filtered and dried to obtain a phosphorus-doped carbon-based porous nanomaterial. (3) Weigh 0.1 g of the phosphorus-doped carbon-based porous material prepared in step (2). Then weigh 0.1 g of urea and a certain mass of ferric nitrate nonahydrate, add 100 ml of deionized water to prepare a uniform solution, and place it in a conical flask. Place the conical flask containing the liquid in an oil bath and keep it warm at 120° C. for 6 hours. (4) placing the product of step (3) into a tubular furnace, heating it to a set temperature in an Ar atmosphere, keeping it warm for a period of time and cooling it to room temperature to obtain the Fe3O4-modified phosphorus-doped carbon-based porous absorbing material.

2. The Fe3O4 modified phosphorus-doped carbon-based porous absorbing material according to claim 1, characterized in that: The molar amount of sodium hypophosphite used in step (2) is controlled at 0.005-0.05 mmol.

3. The Fe3O4 modified phosphorus-doped carbon-based porous absorbing material according to claim 1, characterized in that: The amount of ferric nitrate nonahydrate added in step (3) is 0.3 g.

4. The Fe3O4 modified phosphorus-doped carbon-based porous absorbing material according to claim 1, characterized in that: The heating rate of step (4) is 5°C / min, the holding temperature is 500°C, and the holding time is 6h.

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