CN107454815B

CN107454815B - Cu2O/MWCNTs composite material, preparation method and electromagnetic wave absorption application

Info

Publication number: CN107454815B
Application number: CN201710437401.7A
Authority: CN
Inventors: 高圣涛; 邢宏龙
Original assignee: Anhui University of Science and Technology
Current assignee: Anhui University of Science and Technology
Priority date: 2017-06-09
Filing date: 2017-06-09
Publication date: 2020-05-22
Anticipated expiration: 2037-06-09
Also published as: CN107454815A

Abstract

The invention discloses a Cu₂O/MWCNTs composite material, preparation method and application thereof; the invention synthesizes Cu by a simple chemical method₂O/MWCNTs composite, Cu₂The O nanoparticles grow disorderly on the surface and inside of MWCNTs. The invention adopts a hydrothermal method, does not add any surfactant, avoids the traditional electroplating or chemical plating method, has less pollution, simple and convenient preparation method, environmental protection, easy reaction control, no need of expensive equipment and can be used for industrial production.

Description

Cu2O/MWCNTs composite material, preparation method and electromagnetic wave absorption application

Technical Field

The invention relates to the technical field of nano materials, in particular to Cu₂O/MWCNTs composite material, preparation method and application thereof.

Background

In recent years, with the rapid development of the electronic industry, electromagnetic pollution is becoming more and more serious, and the wave-absorbing material plays a vital role in the field of electromagnetic pollution protection. Meanwhile, the wave-absorbing material plays an important role in the fields of realizing radar stealth of military equipment, weakening electromagnetic interference, ensuring information safety and the like. The wave-absorbing material (microwave absorbing material, electromagnetic wave attenuating material or radar stealth material) can effectively reduce the reflection of electromagnetic waves on the surface of an object, and simultaneously effectively attenuate the electromagnetic waves incident into the material. For the above reasons, microwave absorbing materials have received much attention from researchers at home and abroad.

The wave-absorbing material can be divided into a wave-absorbing agent and a matrix according to the composition. The matrix mainly plays a role in bonding in the wave-absorbing material, and the wave-absorbing agent is a main body of the wave-absorbing material and plays a role in electromagnetic wave loss. The excellent wave absorbing agent needs to meet the requirements of light weight, high absorption strength, wide absorption frequency band, strong electromagnetic loss capability, strong environmental tolerance and the like.

Multi-walled carbon nanotubes (MWCNTs) have the advantages of good chemical stability, excellent thermal stability, high mechanical strength, and excellent electrical conductivity. Meanwhile, the composite material is light in weight and has great potential in the field of preparing excellent wave absorbing agents.

Cuprous oxide is a p-type semiconductor material responding to visible light, the forbidden bandwidth is about 2.0eV, 3d orbitals and 4s orbitals in crystal lattices are not overlapped due to the distance between copper atoms, a semiconductor energy band consisting of a full valence band and an empty conduction band is formed in a system, and the p-type semiconductor material has wide application prospects in the aspects of information functional materials, catalysis, photoelectricity, magnetic materials and the like.

In recent years, there have been many references to Cu₂And (3) research on preparation and application of O. For example, Wangchining et al used a chemical reduction method to prepare cuprous oxide nanoparticles with different shapes and particle sizes by controlling the concentration and pH value of glucose in the solution, and determined the release rate of the cuprous oxide nanoparticles as an antifouling agent in seawater (Wangchining, Zhang Jianfeng, Zhao Wenji et al; Chinese surface engineering; 2015,28, 2); sui et al prepared Cu with truncated octahedron {110} crystal face etched by using an in-situ oxidation etching method and adding two reducing agents of sodium citrate and glucose in sequence₂O nanocage having a wall thickness of 60nm and an outer diameter of 700nm, having a high degree of geometric symmetry (Sui Y M, Zeng Y, Zheng W T, et al₂O and their gas-sensing properties[J].Sens.Actuators B，2012，171-172： 135-140.)。

But due to Cu₂Copper in O is monovalent and is unstable after long-term use and is easily oxidized into divalent copper; cu₂O powder is easy to be aggregated into large particles, so that the performance of the O powder is influenced; and Cu₂O is a semiconductor having a narrow forbidden band width and a high conduction band position, and has a problem of low catalytic efficiency due to recombination of photo-generated electrons and holes. Therefore, at present, many researches on the preparation method of the cuprous oxide/carbon composite material or the copper/carbon composite material are carried out at home and abroad. For example, chinese patent application No. CN201310436145.1 discloses a method for preparing a carbon/graphene supported cuprous oxide nano-scale structure hybrid material by ultrasonic waves, but in the method, reduced graphene (rGO), pyrene derivatives and cupric salt need to react in an organic solvent, the operation is complicated, and the organic solvent pollutes the environment. For another example, chinese patent application No. CN201110459158.1 discloses a method for preparing a copper/carbon nanotube composite superhydrophobic material, the hydrophobic material prepared by the method has high thermal conductivity, high electrical conductivity, and superhydrophobic property, but the treatment process is performedThe method is complex, high temperature and high pressure are required, and the equipment requirement is high.

Therefore, the method for simply and conveniently preparing the cuprous oxide/carbon composite material, particularly the application of the cuprous oxide/carbon nanotube composite material in the wave-absorbing property has been reported.

Disclosure of Invention

Based on the technical problems in the background art, one of the objectives of the present invention is to provide a Cu₂O/MWCNTs composite material.

The second purpose of the invention is to provide Cu₂A preparation method of an O/MWCNTs composite material.

The third purpose of the invention is to provide Cu prepared by the preparation method₂The O/MWCNTs composite material is applied to microwave absorption.

Cu₂O/MWCNTs composite material, Cu in said composite material₂The O nanoparticles grow disorderly on the surface and inside of MWCNTs.

Cu₂The preparation method of the O/MWCNTs composite material comprises the following steps: the method comprises the following steps:

1) pretreatment of the multi-wall carbon nano tube: sequentially adding MWCNTs and concentrated nitric acid into a 250mL three-neck flask, standing after the reaction is finished, performing suction filtration, washing, and performing vacuum drying in an oven at the temperature of 55 ℃ for 24 hours to obtain MWCNTs subjected to acidification treatment by the concentrated nitric acid;

2)Cu₂preparing an O/MWCNTs composite material: adding MWCNTs into distilled water, ultrasonically dispersing for 1H, and then respectively adding CuSO4 & 5H₂O and PEG, magnetically stirring until the O and the PEG are completely dissolved; placing the mixture in an ultrasonic reactor, performing ultrasonic treatment until the mixed solution of a reaction system turns from blue to black, titrating the mixed solution after reaction to pH 11 with a sodium hydroxide solution, and stirring for 120min by using a magnetic stirrer; after the reaction is finished, adding ethanol and distilled water to wash for a plurality of times to obtain solid black particles, putting the collected solid black particles into a drying oven to be dried for 12 hours at the temperature of 60 ℃, putting the obtained flaky sample into a tubular furnace to be calcined at the constant temperature of 300 ℃, and grinding the product obtained after natural cooling to obtain Cu₂O/MWCNTs composite material.

The mass-volume ratio of MWCNTs to concentrated nitric acid in the step 1) is as follows: 0.020-0.180g of 120-200 mL.

The reaction conditions in the step 1): reacting at 100-140 ℃ for 4-8 h.

MWCNTs, distilled water and CuSO4 & 5H in the step 2)₂O, PEG mass to volume ratio: 0.020-0.320 g:60-100mL:0.150-0.35g:0.100-0.300 g.

The concentration of the sodium hydroxide solution in the step 2) is 1-5 wt%, and the titration speed is as follows: 5-10S/drop.

The calcination time in the step 2): 2.5-3.5h, heating rate: 3 ℃/min^-1。

Cu prepared by the method of the application₂O/MWCNTs composite material.

Cu₂The O/MWCNTs composite material is applied to the wave-absorbing material.

XRD test includes adopting LabX XRD-6000 type X-ray diffractometer to characterize the crystal structure of the sample, wherein the X-ray is Cu-K α ray, the wavelength is 0.154nm, the step length is 0.02 degree, the light tube current is 36kV, the current is 30mA, the scanning angle is 20-80 degrees, and the scanning speed is 2 degrees/min^-1。

And (3) testing a scanning electron microscope: adding a small amount of prepared sample into distilled water, performing ultrasonic dispersion, dropwise adding onto conductive adhesive, adhering on a sample table, drying, and characterizing the appearance of the sample by using an FEI-Sirion200 type field emission scanning electron microscope.

And (3) transmission electron microscope testing: the microstructure of the sample was characterized using a JEOL-2010 transmission electron microscope. And (3) taking a small amount of sample to be subjected to ultrasonic dispersion in distilled water, dropwise adding the sample to a copper net, drying, injecting a sample and testing.

And (3) testing microwave absorption performance: and measuring the electromagnetic parameters of the sample by using a vector network analyzer, VNA, AV3629D and China, wherein the test frequency range is 2-18 GHz. Mixing the sample and paraffin according to a mass ratio of 3:1, heating and melting at 80 ℃, pouring into a copper annular mold, and making into a coaxial ring with the thickness of 2mm, the outer diameter of 7mm and the inner diameter of 3mm for testing.

The wave absorbing action mechanism is as follows: cu prepared by the present application₂Cu in O/MWCNTs composite material₂Shape between O nano particle and MWCNTsForming a special conductive network structure and adding Cu₂Conductive paths between O nanoparticles and MWCNTs. Cu₂O nano particles are deposited on MWCNTs and a certain chemical force exists between the O nano particles and the MWCNTs, so that Cu is enabled to be deposited₂O nano particles are fixed on MWCNTs, and polarization generation and Cu-based method₂The capacitor structure formed between the interface of the O nano particles and the MWCNTs creates conditions, and is beneficial to absorption of electromagnetic wave energy of the wave absorber.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention synthesizes Cu by a simple chemical method₂O/MWCNTs composite, Cu₂The O nanoparticles grow disorderly on the surface and inside of MWCNTs.

2. The invention adopts a hydrothermal method, does not add any surfactant, avoids the traditional electroplating or chemical plating method, has less pollution, simple and convenient preparation method, environmental protection, easy reaction control, no need of expensive equipment and can be used for industrial production.

3. The preparation method is simple, and Cu can be successfully prepared by adopting a simple chemical method₂When O is loaded on the surface of the multi-wall carbon nano tube, Cu is also loaded₂O is loaded into the nanotube, and the prepared nano composite material does not need other subsequent treatment, such as calcination in a protective gas atmosphere and the like.

4. The light nano composite material prepared by mixing the nano composite material with paraffin has excellent wave-absorbing performance, can be used in the field of high-temperature wave absorption, has the characteristics of light weight and strong bearing capacity, and combines the multiple loss characteristics of multi-walled carbon nanotubes (MWCNTs) and Cu₂The dielectric loss characteristics of O are combined, and the prepared novel wave-absorbing material can meet the requirements of light weight, strong wave-absorbing capacity, wide absorption frequency band and the like of the novel wave-absorbing material, has higher theoretical and practical values and has good application prospect.

Drawings

FIG. 1 XRD spectrum of MWCNTs composite material;

FIG. 2Cu₂An enlarged SEM picture of the O/MWCNTs composite material;

FIG. 3Cu₂O/MWCNTs composite material Cu₂O-loaded MWCNTs surfaceA TEM photograph of;

FIG. 4Cu₂O/MWCNTs composite material Cu₂TEM image of O grown inside MWCNTs;

FIG. 5Cu₂XPS full spectrum of O/MWCNTs composite material;

FIG. 6Cu₂XPS spectrum of Cu2p of O/MWCNTs composite material;

FIG. 7Cu₂XPS spectrum of CuLM2 of O/MWCNTs composite material;

FIG. 8Cu₂XPS subdivision curve of O1s for O/MWCNTs composites;

FIG. 9Cu₂The reflection loss of the O/MWCNTs composite material is along with the change curve of frequency under different matching layer thicknesses;

FIG. 10Cu₂The cole-cole curve of the O/MWCNTs composite material;

FIG. 11Cu₂Schematic diagram of conductive network of O/MWCNTs composite material.

Detailed Description

The present invention will be further illustrated with reference to the following specific examples.

1. The raw material sources are as follows: concentrated nitric acid, analytically pure, Shanghai Yinyuan chemical Co., Ltd; PEG, 95% alatin; sodium hydroxide, chemically pure, chemical corporation of west longa; CuSO₄·5H₂O, analytically pure, Body chemical Co., Ltd, Tianjin; absolute ethanol, analytically pure, stannless, asian chemical limited company.

2. The instrument equipment comprises: JA2003N electronic balance, shanghai precision scientific instruments ltd; XD-1800D ultrasonic cell disruptor, manufactured by Nanjing Europe instruments Ltd.

Example 1

Cu₂O/MWCNTs composite material, Cu in said composite material₂O nanoparticles grow disordered inside and on the surface of MWCNTs.

The preparation method of the Cu2O/MWCNTs composite material comprises the following steps: the method comprises the following steps:

1) pretreatment of the porous wall carbon nano tube: sequentially adding MWCNTs and concentrated nitric acid into a 250mL three-neck flask, standing after the reaction is finished, performing suction filtration, washing, and performing vacuum drying in an oven at the temperature of 55 ℃ for 24 hours to obtain MWCNTs subjected to acidification treatment by the concentrated nitric acid;

2)Cu₂preparing an O/MWCNTs composite material: adding MWCNTs into distilled water, performing ultrasonic dispersion for 1h, and then respectively adding CuSO₄·5H₂O and PEG, magnetically stirring until the O and the PEG are completely dissolved; placing the mixture in an ultrasonic reactor, performing ultrasonic treatment until the mixed solution of a reaction system turns from blue to black, titrating the mixed solution after reaction to pH 11 with a sodium hydroxide solution, and stirring for 120min by using a magnetic stirrer; after the reaction is finished, adding ethanol and distilled water to wash for a plurality of times to obtain solid black particles, drying the collected solid black particles in a drying oven at 60 ℃ for 12 hours, then placing the obtained flaky sample in a tubular furnace to calcine at constant temperature, and grinding the product obtained after natural cooling to obtain Cu₂O/MWCNTs composite material.

The mass-volume ratio of MWCNTs to concentrated nitric acid in the step 1) is as follows: 0.020g, 120 mL.

The reaction conditions in the step 1): the reaction was carried out at 100 ℃ for 4 h.

MWCNTs, distilled water and CuSO in the step 2)₄·5H₂O, PEG mass to volume ratio: 0.020g: 60mL of: 0.150 g:0.100 g.

The concentration of the sodium hydroxide solution in the step 2) is 1 wt%, and the titration speed is as follows: 10S/drop.

The temperature of constant-temperature calcination in the step 2) is 300 ℃, and the calcination time is as follows: 2.5h, heating rate: 3 ℃/min^-1。

Referring to FIGS. 1-11:

FIG. 1 shows Cu prepared in example 1₂XRD spectrogram of the O/MWCNTs composite material; 2 θ 29.73 °, 36.58 °, 42.44 °, 61.45 °, 73.64 ° and 77.45 ° with Cu₂The positions of the crystal faces of (JCPDS Card No.05-0667) (110), (111), (200), (220), (311) and (222) of the O standard are consistent. The characteristic peak at 25.57 ° 2 θ corresponds to the (002) crystal plane of the MWCNTs hexagonal graphite structure, and the intensity of the peak is weak, probably due to Cu₂The O nano particles are well distributed in MWCNTs. No other characteristic peak is seen in the figure, which shows that pure Cu is prepared under the experimental condition₂O nanoparticles。

FIGS. 2 to 4 are Cu₂SEM photograph and TEM photograph of the O/MWCNTs composite material; FIGS. 2-3Cu₂O nano particles are attached to the surface of MWCNTs in a disordered way, and FIG. 4 shows that part of Cu₂The O nanoparticles grow disordered inside the MWCNTs. In FIG. 3, it can be seen that two adjacent Cu2O nanoparticles are tightly bound to two intersecting MWCNTs, forming a polarized and capacitor-like structure, which is paired with Cu₂The dielectric property and the conductive property of the O/MWCNTs composite material have great influence.

The binding energy of copper atoms to oxygen atoms was measured by X-ray photoelectron spectroscopy (XPS), and FIG. 5 shows Cu₂XPS spectrum of O/MWCNTs composite material. FIG. 6 shows that C, O, Cu element was detected on the surface of the sample, together with Cu₂The constituent elements of the O/MWCNTs compound are consistent. Fig. 7 is a Cu2p spectrum. The peak energy spectra of 933.9eV and 954.5eV are respectively Cu2p3/2 and Cu2p1/2, and the peak energy spectra are increased and shifted to the direction of high binding energy compared with the peak energy spectra of standard Cu2p3/2 and Cu2p 1/2. The chemical environment of the copper is changed, and probably the copper is subjected to coordination with other atoms, partial electrons are lost, the electron cloud density of valence electrons is reduced, the shielding effect on electrons of an inner shell layer is also reduced, and the binding energy of the electrons of the inner shell layer is increased. FIG. 8 is a spectrum of CuLM 2. The peak of the spectrum is located at 916.5eV, which shows that the copper element in the composite material exists only in the form of monovalent copper. The absence of other peaks between the peaks of the spectra of Cu2p3/2 and Cu2p1/2 further excludes Cu²⁺The presence of a compound. In fig. 8, the peak of the spectrum of the binding energy 530.7eV is a characteristic peak of O1s of the carbonyl oxygen atom, which is lower than the O1s standard binding energy of the carbonyl oxygen atom, because the carbonyl oxygen atom gains part of electrons of the Cu atom to lower its binding energy. The peaks of the spectrum of the binding energies 532.2eV and 533.4eV are characteristic peaks of O1s for Cu-O and C-O-C, respectively. Thus, it can be seen that: cu₂The interaction between O and MWCNTs is Cu₂Copper atoms in the O nanoparticles are generated with carbonyl oxygen atoms in the MWCNTs.

FIG. 9 is Cu₂The reflection loss of the O/MWCNTs composite material is plotted along with the frequency under different thicknesses of the matching layer. When the thickness of the wave absorbing agent is only 1.5mm, the maximum reflection loss value reaches-28.8 dB at 2-18GHz, and the reflection loss value is less thanThe maximum absorption width at-10 dB is 2.7GHz (10.7-13.4GHz), and when the thickness of the wave absorbing agent is 2.0mm, the maximum reflection loss value at 2-18GHz reaches-40.5 dB. Experimental data show that the microwave absorption of different frequency bands can be met by adjusting the thickness of the prepared wave absorbing agent.

Cu₂The O/MWCNTs composite material has excellent wave absorption performance probably due to the combined action of three factors of dielectric loss, impedance matching and interface relaxation. According to debye's theory, epsilon "represents the dielectric loss, which is composed of conduction loss and polarization. Debye polarization relaxation may help to further understand the dielectric loss mechanism of the wave absorber. FIG. 10 is Cu₂The cole-cole curve of the O/MWCNTs composite material. At least 4 semicircles appear in the curve, each representing a debye relaxation process, indicating that the dielectric loss of the wave absorber is a complex dielectric relaxation process. Cu₂O-MWCNTs and Cu₂O-Cu₂O interface polarization also increases the ε "value.

Cu₂A key contributor to the dielectric properties of O/MWCNTs composites is the electrical conductivity of the composite. FIG. 11 is based on Cu₂Electrical properties of O and MWCNTs and Cu₂The conductive network schematic diagram is provided by the microstructure characteristics of the O/MWCNTs composite material. Cu₂The special structure of the O/MWCNTs composite material can form a conductive network to increase Cu₂Conductive paths between O nanoparticles and MWCNTs. Cu₂O nano particles are deposited on MWCNTs and a certain chemical force exists between the O nano particles and the MWCNTs, so that Cu is enabled to be deposited₂O nano particles are fixed on MWCNTs, and polarization generation and Cu-based method₂The capacitor structure formed between the interface of the O nano particles and the MWCNTs creates conditions, and is beneficial to absorption of electromagnetic wave energy of the wave absorber.

Example 2

The mass-volume ratio of MWCNTs to concentrated nitric acid in the step 1) is as follows: 0.180g, 200 mL.

The reaction conditions in the step 1): the reaction was carried out at 140 ℃ for 8 h.

MWCNTs, distilled water and CuSO in the step 2)₄·5H₂O, PEG mass to volume ratio: 0.020g: 100mL of: 0.35g: 0.300 g.

The concentration of the sodium hydroxide solution in the step 2) is 5 wt%, and the titration speed is as follows: 10S/drop.

The temperature of constant-temperature calcination in the step 2) is 300 ℃, and the calcination time is as follows: 3.5h, heating rate: 3 ℃/min^-1。

When the thickness of the wave absorbing agent is only 1.5mm, the maximum reflection loss value reaches-26.8 dB at 2-18GHz, the maximum absorption width is 2.5GHz (10.7-13.4GHz) when the reflection loss value is less than-10 dB, and when the thickness of the wave absorbing agent is 2.0mm, the maximum reflection loss value reaches-42.5 dB at 2-18 GHz.

Example 3

Cu₂O/MWCNTs composite material, Cu in said composite material₂The O nanoparticles grow disordered inside the MWCNTs.

Cu according to claim 1₂The preparation method of the O/MWCNTs composite material comprises the following steps: the method comprises the following steps:

The mass-volume ratio of MWCNTs to concentrated nitric acid in the step 1) is as follows: 0.10g, 160 mL.

The reaction conditions in the step 1): the reaction was carried out at 120 ℃ for 6 h.

MWCNTs, distilled water and CuSO in the step 2)₄·5H₂O, PEG mass to volume ratio: 0.120 g: 80mL of: 0.25 g: 0.15 g.

The concentration of the sodium hydroxide solution in the step 2) is 3 wt%, and the titration speed is as follows: 8S/drop.

The temperature of constant-temperature calcination in the step 2) is 300 ℃, and the calcination time is as follows: 3h, heating rate: 3 ℃/min^-1。

When the thickness of the wave absorbing agent is only 1.5mm, the maximum reflection loss value reaches-30.1 dB at 2-18GHz, the maximum absorption width is 2.3GHz (10.7-13.4GHz) when the reflection loss value is less than-10 dB, and when the thickness of the wave absorbing agent is 2.0mm, the maximum reflection loss value reaches-41.2 dB at 2-18 GHz.

Example 4

Cu₂The preparation method of the O/MWCNTs composite material comprises the following steps: the method comprises the steps ofThe following:

The mass-volume ratio of MWCNTs to concentrated nitric acid in the step 1) is as follows: 0.060g, 130 mL.

The reaction conditions in the step 1): reacting at 100-140 ℃ for 4-8 h.

MWCNTs, distilled water and CuSO4 & 5H in the step 2)₂O, PEG mass to volume ratio: 0.32g: 65mL of: 0.18 g: 0.16 g.

The concentration of the sodium hydroxide solution in the step 2) is 2.5 wt%, and the titration speed is as follows: 6S/drop.

The calcination time in the step 2): 3.0h, heating rate: 3 ℃/min^-1。

Cu prepared by the method of the application₂O/MWCNTs composite material.

When the thickness of the wave absorbing agent is only 1.5mm, the maximum reflection loss value reaches-28.4 dB at 2-18GHz, the maximum absorption width is 2.9GHz (10.7-13.4GHz) when the reflection loss value is less than-10 dB, and when the thickness of the wave absorbing agent is 2.0mm, the maximum reflection loss value reaches-43.5 dB at 2-18 GHz.

Example 5

Cu₂O/MWCNTs composite material, the composite materialCu in composite material₂The O nanoparticles grow disorderly on the surface and inside of MWCNTs.

The mass-volume ratio of MWCNTs to concentrated nitric acid in the step 1) is as follows: 0.035g, 160 mL.

The reaction conditions in the step 1): the reaction was carried out at 125 ℃ for 5.5 h.

MWCNTs, distilled water and CuSO4 & 5H in the step 2)₂O, PEG mass to volume ratio: 0.320 g:60-100mL: 0.26 g: 0.175 g.

The calcination time in the step 2): 3.0h, heating rate: 3 ℃/min^-1。

Cu prepared by the method of the application₂O/MWCNTs composite material.

When the thickness of the wave absorbing agent is only 1.5mm, the maximum reflection loss value reaches-24.2 dB at 2-18GHz, the maximum absorption width is 2.5GHz (10.7-13.4GHz) when the reflection loss value is less than-10 dB, and when the thickness of the wave absorbing agent is 2.0mm, the maximum reflection loss value reaches-39.8 dB at 2-18 GHz.

Example 6

The mass-volume ratio of MWCNTs to concentrated nitric acid in the step 1) is as follows: 0.160g, 190 mL.

The reaction conditions in the step 1): the reaction was carried out at 138 ℃ for 4.6 h.

MWCNTs, distilled water and CuSO4 & 5H in the step 2)₂O, PEG mass to volume ratio: 0.284 g:60-100mL: 0.32g: 0.176 g.

The concentration of the sodium hydroxide solution in the step 2) is 4.2 wt%, and the titration speed is as follows: 9S/drop.

The calcination time in the step 2): 3.0h, heating rate: 3 ℃/min^-1。

Cu prepared by the method of the application₂O/MWCNTs composite material.

When the thickness of the wave absorbing agent is only 1.5mm, the maximum reflection loss value reaches-29.1 dB at 2-18GHz, the maximum absorption width is 2.4GHz (10.7-13.4GHz) when the reflection loss value is less than-10 dB, and when the thickness of the wave absorbing agent is 2.0mm, the maximum reflection loss value reaches-38.5 dB at 2-18 GHz.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims

1. Cu₂An O/MWCNTs composite material, characterized in that Cu in the composite material₂The O nano particles grow on the surface and the inside of the MWCNTs in an unordered manner; the preparation method comprises the following steps:

2)Cu₂preparing an O/MWCNTs composite material: adding MWCNTs into distilled water, ultrasonically dispersing for 1H, and then respectively adding CuSO4 & 5H₂O and PEG, magnetically stirring until the O and the PEG are completely dissolved; placing the mixture in an ultrasonic reactor, performing ultrasonic treatment until the mixed solution of a reaction system turns from blue to black, titrating the mixed solution after reaction to pH 11 with a sodium hydroxide solution, and stirring for 120min by using a magnetic stirrer; after the reaction is finished, adding ethanol and distilled water to wash for a plurality of times to obtain solid black particles, putting the collected solid black particles into a drying oven to be dried for 12 hours at the temperature of 60 ℃, putting the obtained flaky sample into a tubular furnace to be calcined at the constant temperature of 300 ℃, and grinding the product obtained after natural cooling to obtain Cu₂O/MWCNTs composite material;

MWCNTs, distilled water and CuSO in the step 2)₄·5H₂O, PEG mass to volume ratio: 0.020-0.32g, 60-100mL, 0.150-0.35g, 0.100-0.300 g.

2. Cu according to claim 1₂The O/MWCNTs composite material is characterized in that the mass-volume ratio of MWCNTs to concentrated nitric acid in the step 1): 0.020-0.180g of 120-200 mL.

3. Cu according to claim 1₂O/MWCNTs composite material, characterized in that the reaction conditions in step 1): reacting at 100-140 ℃ for 4-8 h.

4. Cu according to claim 1₂The O/MWCNTs composite material is characterized in that the concentration of the sodium hydroxide solution in the step 2) is 1-5 wt%, and the titration speed is as follows: 5-10S/drop.

5. Cu according to claim 1₂The O/MWCNTs composite material is characterized in that the calcination time in the step 2): 2.5-3.5h, heating rate: 3 ℃/min-1.

6. Cu according to claim 1₂The O/MWCNTs composite material is applied to the wave-absorbing material.