Carbon-loaded high-entropy oxide and preparation method thereof

Abstract

The invention discloses a carbon-loaded high-entropy oxide and a preparation method thereof, the carbon-loaded high-entropy oxide is of a core-shell structure formed by coating carbon with a high-entropy oxide, and the high-entropy oxide comprises at least five metal elements of chromium, manganese, iron, cobalt, nickel and copper. The carbon-loaded high-entropy oxide has the advantages of low density, high dielectric loss and excellent wave-absorbing performance, and is expected to be widely applied to electromagnetic absorption and elimination in the fields of electronics, communication civil affairs and aerospace military.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial preparation technology, and relates to a carbon-supported high-entropy oxide and its preparation method. Background Art

[0002] The commercial application of mobile communication technology has led to the rapid development of various fields such as the Industrial Internet, the Internet of Vehicles, autonomous driving, smart homes, and smart cities. However, the resulting electronic products and higher-frequency millimeter-wave electromagnetic radiation are increasingly present in people's daily lives. Electromagnetic interference not only affects the normal operation of various electromagnetic and communication devices but also poses a threat to people's health. High-entropy oxides possess unique dielectric and magnetic properties, and have broad application prospects in the field of microwave absorbing materials.

[0003] High-entropy oxides currently used in microwave absorption have limited absorption capabilities due to their single-phase nature, insufficient dielectric loss, and high density, making them unsuitable for use in precision components. Their primary preparation method is high-temperature sintering, which involves prolonged sintering at temperatures above 700°C, resulting in high time costs and significantly limiting product manufacturing.

[0004] Therefore, it is of great significance to develop a simple and efficient method for preparing carbon-supported high-entropy oxides that combines a high-entropy phase with a lightweight and highly conductive carbon phase. Summary of the Invention

[0005] To overcome the aforementioned problems, the inventors conducted intensive research and developed a carbon-supported high-entropy oxide and its preparation method. The method involves placing five or more metallic phase raw materials and carbon materials in a solvent, followed by co-precipitation, filtration, drying, and plasma flow to obtain the carbon-supported high-entropy oxide. In the obtained carbon-supported high-entropy oxide, the high-entropy oxide adheres to the carbon material, forming a core-shell structure. This structure exhibits advantages such as low density, high dielectric loss, and excellent microwave absorption performance, and is expected to be widely used in electromagnetic absorption and elimination in the electronics, communications, and aerospace / military fields, thus completing this invention.

[0006] Specifically, the object of the present invention is to provide the following aspects:

[0007] On the one hand, a carbon-supported high-entropy oxide is provided, wherein the carbon-supported high-entropy oxide has a core-shell structure in which high-entropy oxide is coated with carbon, and the particle size of the high-entropy oxide is between 0.05 and 0.15 μm.

[0008] Among them, based on the total mass of carbon-supported high-entropy oxides, the mass ratio of high-entropy oxides is 3-30 wt%.

[0009] The density of the carbon-supported high-entropy oxide is between 2.5 and 4.5 g / cm³. 3 .

[0010] The carbon-loaded high-entropy oxide includes at least five metallic elements selected from chromium, manganese, iron, cobalt, nickel, and copper.

[0011] On the other hand, a method for preparing the carbon-supported high-entropy oxide described in the first aspect is provided, the method comprising:

[0012] Step 1: Place the metallic phase raw material and carbon material in a solvent to obtain a mixture;

[0013] Step 2: Pre-treat the mixture to obtain precursor powder;

[0014] Step 3: The precursor powder is subjected to plasma flow treatment to obtain the carbon-supported high-entropy oxide.

[0015] In step 1, the metal phase raw material is a soluble metal salt, including at least five of the following: chromium source, manganese source, iron source, cobalt source, nickel source, and copper source.

[0016] In step 1, the carbon material is mesophase carbon microspheres.

[0017] In step 2, the pretreatment includes co-precipitation, filtration, washing, and drying in sequence.

[0018] Step 2 includes the following steps:

[0019] Step 2-1: Co-precipitate the mixture to obtain a suspension;

[0020] Step 2-2: The suspension is sequentially filtered, washed and dried to obtain precursor powder.

[0021] In this process, co-precipitation is performed using a precipitant, which is a strong base, preferably sodium hydroxide or potassium hydroxide.

[0022] The beneficial effects of this invention include:

[0023] (1) The carbon-loaded high-entropy oxide provided by the present invention has the advantages of low density, high dielectric loss and excellent wave absorption performance, and is expected to be widely used in electromagnetic absorption and elimination in the fields of electronics, communications, civil and aerospace military fields.

[0024] (2) The carbon-loaded high-entropy oxide provided by the present invention has a particle size of 0.05 to 0.15 μm. The high-entropy oxide is loaded on the surface of carbon material to form a core-shell structure, thereby enhancing the interfacial polarization and dielectric loss.

[0025] (3) The method for preparing carbon-supported high-entropy oxides provided by the present invention utilizes plasma jet to crystallize each metal phase into high-entropy oxide nanoparticles in a very short time. The rapid cooling of the plasma jet effectively suppresses phase segregation and abnormal particle growth.

[0026] (4) The method for preparing carbon-supported high-entropy oxides provided by the present invention has a short plasma jet action time, low cost and simple process, which greatly improves production efficiency and is easy to realize industrial production. Attached Figure Description

[0027] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0028] In the attached diagram:

[0029] Figure 1(a) shows the energy spectrum of the carbon-supported high-entropy oxide prepared in Example 1;

[0030] Figure 1(b) shows the energy spectrum of carbon in the carbon-supported high-entropy oxide prepared in Example 1;

[0031] Figure 1(c) shows the energy spectrum of oxygen in the carbon-supported high-entropy oxide prepared in Example 1;

[0032] Figure 1(d) shows the energy spectrum of Cr in the carbon-supported high-entropy oxide prepared in Example 1;

[0033] Figure 1(e) shows the energy spectrum of Mn in the carbon-supported high-entropy oxide prepared in Example 1;

[0034] Figure 1(f) shows the energy spectrum of Fe in the carbon-supported high-entropy oxide prepared in Example 1;

[0035] Figure 1(g) shows the energy spectrum of Co in the carbon-supported high-entropy oxide prepared in Example 1;

[0036] Figure 1(h) shows the energy spectrum of Ni in the carbon-supported high-entropy oxide prepared in Example 1;

[0037] Figure 1(i) shows the energy spectrum of Cu in the carbon-supported high-entropy oxide prepared in Example 1;

[0038] Figure 2 The image shown is a transmission electron microscope (TEM) image of the carbon-loaded high-entropy oxide prepared in Example 1.

[0039] Figure 3 The diagram shows the particle size distribution of the high-entropy phase in the carbon-supported high-entropy oxide prepared in Example 1.

[0040] Figure 4 A comparison chart of dielectric loss tangents of the carbon-supported high-entropy oxide prepared in Example 1, the high-entropy oxide prepared in Comparative Example 1, and the high-entropy oxide prepared in Comparative Example 2 is shown.

[0041] Figure 5 This shows a three-dimensional image of electromagnetic wave absorption and reflection of the carbon-loaded high-entropy oxide prepared in Example 1;

[0042] Figure 6 The image shown is a scanning electron microscope image of the high-entropy oxide prepared in Comparative Example 1.

[0043] Figure 7 A three-dimensional image of electromagnetic wave absorption and reflection of the high-entropy oxide prepared in Comparative Example 1 is shown.

[0044] Figure 8 The particle size distribution of the high-entropy oxides prepared in Comparative Example 2 is shown.

[0045] Figure 9 The image shown is a scanning electron microscope image of the high-entropy oxide prepared in Comparative Example 2.

[0046] Figure 10(a) shows a scanning electron microscope image of the high-entropy oxide prepared in Comparative Example 3 at the 200 nm scale;

[0047] Figure 10(b) shows a scanning electron microscope image of the high-entropy oxide prepared in Comparative Example 3 at the 5 μm scale;

[0048] Figure 11 The image shown is a scanning electron microscope image of the high-entropy oxide prepared in Comparative Example 4. Detailed Implementation

[0049] The following will refer to the appendix. Figures 1(a) to 11 Specific embodiments of the invention will be described in more detail below. While specific embodiments of the invention are shown in the accompanying drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0050] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions are preferred embodiments for carrying out the invention; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.

[0051] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship in the working state of this invention, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0052] To facilitate understanding of the embodiments of the present invention, further explanations and descriptions will be provided below with reference to the accompanying drawings and specific embodiments. The accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0053] On the one hand, according to the carbon-supported high-entropy oxide provided by the present invention, the carbon-supported high-entropy oxide is a core-shell structure of high-entropy oxide coated with carbon, the particle size of the high-entropy oxide is between 0.05 and 0.15 μm, and the proportion of high-entropy oxide is 3 to 30 wt% based on the total mass of the carbon-supported high-entropy oxide.

[0054] Furthermore, the dielectric loss tangent of the carbon-loaded high-entropy oxide is between 0.3 and 0.5, and its density is between 2.5 and 4.5 g / cm³. 3 The carbon-supported high-entropy oxide exhibits excellent electromagnetic wave absorption properties.

[0055] In one embodiment, the carbon-loaded high-entropy oxide has a dielectric loss tangent between 0.3 and 0.5, a minimum reflection loss RLmin of -44.7 dB (99.997% electromagnetic wave attenuation) at room temperature, and a maximum effective absorption bandwidth (EAB) of 4.3 GHz.

[0056] According to the present invention, the carbon-loaded high-entropy oxide includes at least five metallic elements selected from chromium, manganese, iron, cobalt, nickel and copper. Preferably, the high-entropy oxide includes six metallic elements selected from chromium, manganese, iron, cobalt, nickel and copper.

[0057] On the other hand, a method for preparing the carbon-supported high-entropy oxide described in the first aspect is provided, the method comprising:

[0058] Step 1: Place the metallic phase raw material and carbon material in a solvent to obtain a mixture;

[0059] Step 2: Pre-treat the mixture to obtain precursor powder;

[0060] Step 3: The precursor powder is subjected to plasma flow treatment to obtain the carbon-supported high-entropy oxide.

[0061] The preparation method of the carbon-supported high-entropy oxide is described in detail below.

[0062] Step 1: Place the metallic raw material and carbon material in a solvent to obtain a mixture.

[0063] In step 1, the metal phase raw material is a soluble metal salt, specifically including at least five of the following: chromium source, manganese source, iron source, cobalt source, nickel source and copper source. Preferably, the metal phase raw material includes chromium source, manganese source, iron source, cobalt source, nickel source and copper source.

[0064] In step 1, the metal phase raw material is preferably a soluble metal salt with the same cation radius and mutual solid solubility to ensure the formation of single-phase high-entropy oxide.

[0065] In a preferred embodiment, the metal phase raw material is selected from at least five of the following: chromium chloride hexahydrate, manganese chloride tetrahydrate, anhydrous ferric chloride, cobalt chloride hexahydrate, nickel chloride hexahydrate, anhydrous copper chloride, zinc chloride, and vanadium chloride; more preferably, the metal phase raw material is chromium chloride hexahydrate, manganese chloride tetrahydrate, anhydrous ferric chloride, cobalt chloride hexahydrate, nickel chloride hexahydrate, and anhydrous copper chloride.

[0066] In step 1, the molar ratio of soluble metal salts in the metal phase raw material is preferably an equimolar ratio, which helps to reduce the generation of metal oxide impurities and improve the uniformity of single-phase high-entropy oxides.

[0067] In step 1, the carbon material is the carrier for the final carbon-loaded high-entropy oxide. The carbon material is mesophase carbon microspheres, which can be any commercially available type, such as mesophase carbon microspheres produced by Parkway Technology Co., Ltd.

[0068] The particle size of the mesophase carbon microspheres is between 20 and 40 μm, preferably between 25 and 30 μm.

[0069] Furthermore, the mesophase carbon microspheres exhibit low internal stress and a stable carbon structure, resulting in excellent electrical conductivity and significant resistance loss. They also possess numerous micropores, enhancing the reflection path of electromagnetic waves within the material and reducing electromagnetic loss. Typically, carbon-loaded high-entropy oxides prepared from mesophase carbon microspheres with a particle size between 20 and 40 μm exhibit superior performance, with mesophase carbon microspheres with a particle size between 25 and 30 μm showing particularly outstanding results.

[0070] In step 1, the solvent only needs to be able to dissolve the metal phase raw material and not react with it. It is preferably any one or more of water, ethanol, methanol, and isopropanol, with water being the most readily available.

[0071] Furthermore, the amount of solvent used does not need to be large, just enough to disperse the metallic phase raw material and the carbon material. The mass ratio (mg:mL) of the carbon material to the volume ratio (mL) of the solvent is (8-15):1, preferably (9-12):1, for example 10:1.

[0072] In step 1, the mass ratio between the metal phase ions and carbon materials in the metal phase raw material is 1:(1-10), preferably 1:(1-5), for example 1:3, in order to obtain carbon-loaded high-entropy oxide with excellent microwave absorption performance.

[0073] According to a preferred embodiment, in step 1, the carbon material is dispersed in a solvent, and then a soluble metal salt solution is added dropwise. The mixture is stirred and dispersed for 20 to 40 minutes, or 30 minutes, so that the solute in the mixture is evenly dispersed.

[0074] The concentration of the corresponding metal ions in each soluble metal salt solution is 0.3–0.5 mol / L, for example, 0.4 mol / L.

[0075] Step 2: Pre-treat the mixture to obtain precursor powder.

[0076] In step 2, the pretreatment sequentially includes co-precipitation, filtration, washing, and drying.

[0077] According to a preferred embodiment, step 2 includes the following steps:

[0078] Step 2-1: Co-precipitate the mixture to obtain a suspension;

[0079] Step 2-2: The suspension is sequentially filtered, washed and dried to obtain precursor powder.

[0080] In step 2-1, co-precipitation is performed using a precipitant, which causes the metal ions in the metallic phase raw material to precipitate. The precipitant should be chosen to produce a pure precipitate that is easy to filter. For chromium ions, manganese ions, iron ions, cobalt ions, nickel ions, and copper ions, strong bases are excellent precipitants, preferably either sodium hydroxide or potassium hydroxide, and more preferably sodium hydroxide, which has a milder reaction.

[0081] In step 2-1, in order to precipitate more metal salt ions evenly, the added strong base should be in excess. Depending on the preferred type of salt ion, the molar ratio of the total added metal cations to sodium hydroxide is 1:(4-5), preferably 1:(4-4.3), for example 1:4.2.

[0082] In step 2-1, the longer the co-precipitation time, the better, typically 1.5h to 3h, preferably 1.5h to 2.5h, for example 2h. Stirring may be arbitrarily included during co-precipitation.

[0083] In step 2-2, the detergent is either deionized water or anhydrous ethanol, preferably deionized water.

[0084] In step 2-2, the drying is freeze drying, and the drying time is 36 to 72 hours, preferably 40 to 50 hours, and more preferably 48 hours.

[0085] Step 3: The precursor powder is subjected to plasma jet treatment to obtain the carbon-supported high-entropy oxide.

[0086] The inventors have discovered that plasma jet treatment of precursor powder can crystallize various metal phases into high-entropy oxide nanoparticles within an extremely short time. The rapid cooling of the plasma jet effectively suppresses phase segregation and abnormal particle growth. The second-level plasma synthesis rate avoids reactions between metal oxides and carbon, preventing the formation of carbides and ensuring the formation of a strongly coupled interface between the high-entropy phase and the carbon phase.

[0087] In this invention, during plasma jet processing, the temperature can reach 1300K to 2500K, such as 1500K, depending on the processing time. The rapid cooling system of the plasma jet, such as a water cooling system, can reduce the sample to room temperature within 1 to 5 minutes.

[0088] In this invention, the current used in plasma jet treatment is 30-70A, preferably 40-60A, for example 50A; the treatment time is 0.1-60s, preferably 2-30s, for example 2s, 3s or 5s; and the number of plasma jet treatments is 2-5 times, preferably 2-3 times, for example 3 times.

[0089] The inventors have discovered that when plasma jet processing is performed, if the current used is too small, the time is too short, and / or the number of times is too few, it is impossible to completely crystallize the high-entropy oxides; if the current used is too large, the time is too long, and / or the number of times is too many, it will cause the high-entropy oxides to agglomerate.

[0090] In this invention, the gas used in plasma jet treatment is nitrogen or inert gas such as argon or helium. The inert gas is mainly used to generate plasma and protect the high-entropy phase from ablation, while preventing the carbon material from being oxidized and volatilized at high temperature under the action of plasma flow.

[0091] Furthermore, the gas flow rate is 500–700 mL / min, preferably 550–650 mL / min, for example 600 mL / min. When the gas flow rate is too low, the plasma jet has too weak an effect on the surface of the mixed phase to crystallize the high-entropy oxide; but when the gas flow rate is too high, the plasma jet has too strong an effect on the surface of the high-entropy phase, thus causing its aggregation.

[0092] Example

[0093] The present invention is further described below through specific examples; however, these examples are merely exemplary and do not constitute any limitation on the scope of protection of the present invention.

[0094] Example 1

[0095] Six metal ion solutions were prepared using water: CrCl3·6H2O, MnCl2·4H2O, FeCl3, CoCl2·6H2O, NiCl2·6H2O, and CuCl2. The concentration of the metal cation in each of the six metal ion solutions was 0.4 mol / L.

[0096] Weigh 1000 mg of mesophase carbon microspheres (purchased from Puwei Technology Co., Ltd., with a particle size of 25-30 μm) into a beaker, add 100 mL of deionized water, and add 2.5 mL of each of the above-mentioned metal ion solutions. Stir for 30 min to disperse and obtain a mixed solution. Then slowly add 25 mmol of NaOH solution to the mixed solution and continue stirring for 2 h to obtain a suspension.

[0097] The suspension was filtered, washed with deionized water, and freeze-dried for 48 hours to obtain the precursor powder.

[0098] To obtain carbon-loaded high-entropy oxides, the precursor powder is placed directly below the plasma jet and subjected to plasma jet treatment under the following conditions: the gas used is argon (flow rate of 600 ml / min), the current is 50 A, the treatment time is 3 seconds, and this operation is repeated 3 times. During the plasma jet treatment, the temperature reaches 1500 K.

[0099] The obtained carbon-supported high-entropy oxide contained 27% high-entropy oxide by mass, and its density was 2.8 g / cm³. 3 .

[0100] Figure 1(a) shows the energy spectrum of the prepared carbon-supported high-entropy oxide, Figure 1(b) shows the energy spectrum of carbon in the prepared carbon-supported high-entropy oxide, Figure 1(c) shows the energy spectrum of oxygen in the prepared carbon-supported high-entropy oxide, Figure 1(d) shows the energy spectrum of Cr in the prepared carbon-supported high-entropy oxide, Figure 1(e) shows the energy spectrum of Mn in the prepared carbon-supported high-entropy oxide, Figure 1(f) shows the energy spectrum of Fe in the prepared carbon-supported high-entropy oxide, Figure 1(g) shows the energy spectrum of Co in the prepared carbon-supported high-entropy oxide, Figure 1(h) shows the energy spectrum of Ni in the prepared carbon-supported high-entropy oxide, and Figure 1(i) shows the energy spectrum of Cu in the prepared carbon-supported high-entropy oxide. It can be seen that the six elements Cr, Mn, Fe, Co, Ni and Cu are distributed in a consistent manner, and no obvious phase separation phenomenon was observed, indicating that the high-entropy oxide was successfully synthesized. Figure 2 The transmission electron microscope image of the carbon-supported high-entropy oxide is shown. It can be seen that the high-entropy oxide (shown as high-entropy in the figure) is attached around the mesophase carbon microspheres (shown as carbon phase in the figure), forming a core-shell composite structure. Figure 3 The particle size distribution of the high-entropy phase in carbon-supported high-entropy oxides is shown, indicating that the particle size of the high-entropy oxides is mainly concentrated at 0.14 μm.

[0101] Carbon-loaded high-entropy oxide was mixed with molten paraffin at a 1:1 mass ratio, and then pressed into a coaxial ring shape in a mold. The outer diameter of the ring was 7 mm and the inner diameter was 3 mm. The relative complex permittivity and relative complex permeability of the carbon-loaded high-entropy oxide were measured using a network vector analyzer in the 2-18 GHz range. The three-dimensional electromagnetic wave absorption and reflection plot was obtained using the following formula:

[0102]

[0103]

[0104] Where Z0 is the vacuum characteristic impedance, Z in ε represents the normalized input impedance of the electromagnetic absorbing material. r and μ r Let f represent the relative complex permittivity and relative complex permeability of the material, d represent the frequency of the electromagnetic wave, c represent the thickness of the electromagnetic absorbing material, tanh represent the speed of light in vacuum, and j represent the imaginary number. The obtained three-dimensional electromagnetic wave absorption and reflection diagram is shown below. Figure 5As shown, carbon-loaded high-entropy oxides possess excellent electromagnetic wave absorption performance. Under normal temperature conditions, the minimum reflection loss (effective absorption bandwidth EAB is the frequency band where the reflection loss is less than -10dB) RLmin is -44.7dB (99.997% electromagnetic wave attenuation), and the maximum effective absorption bandwidth (EAB) is 4.3GHz.

[0105] Comparative Example

[0106] Comparative Example 1

[0107] Six metal ion solutions were prepared using water: CrCl3·6H2O, MnCl2·4H2O, FeCl3, CoCl2·6H2O, NiCl2·6H2O, and CuCl2. The concentration of the metal cation in each solution was 0.4 mol / L. Then, 2.5 mL of each solution was added dropwise to 100 mL of deionized water, and the mixture was stirred for 30 min to disperse the ions, resulting in a mixed solution. Finally, 25 mmol of NaOH solution was slowly added to the mixed solution, and the mixture was stirred for another 2 h to obtain a suspension.

[0108] The suspension was filtered, washed with deionized water, and freeze-dried for 48 hours to obtain the precursor powder.

[0109] High-entropy oxides can be obtained by placing the precursor powder directly below the plasma jet and performing plasma jet treatment under the following conditions: the gas used is argon (flow rate of 600 ml / min), the current is 50 A, the treatment time is 3 seconds, and this operation is performed 3 times consecutively. During the plasma jet treatment, the temperature reaches 1500 K.

[0110] Figure 6 The scanning electron microscope image of the high-entropy oxide prepared is shown. It can be found that the high-entropy oxide particles crystallized under plasma flow are small in size, about 135 nm, and are relatively loose with gaps between defects.

[0111] The three-dimensional image of electromagnetic absorption and reflection of high-entropy oxide was obtained in the same manner as in Example 1, as follows: Figure 7 As shown, it can be seen that the minimum reflection loss RLmin of the high-entropy oxide single-phase system is greater than -10dB, indicating poor electromagnetic absorption performance.

[0112] Will Figure 7 and Figure 5 By comparison, it can be seen that the introduction of a carbon phase into a high-entropy oxide increases the dielectric loss of the material, generates polarization loss at the two-phase interface, and significantly enhances the electromagnetic absorption performance.

[0113] Comparative Example 2

[0114] Six metal ion solutions were prepared using water: CrCl3·6H2O, MnCl2·4H2O, FeCl3, CoCl2·6H2O, NiCl2·6H2O, and CuCl2. The concentration of the metal cation in each solution was 0.4 mol / L. Then, 2.5 mL of each solution was added dropwise to 100 mL of deionized water, and the mixture was stirred for 30 min to disperse the ions, resulting in a mixed solution. Finally, 25 mmol of NaOH solution was slowly added to the mixed solution, and the mixture was stirred for another 2 h to obtain a suspension.

[0115] The suspension was filtered, washed with deionized water, and freeze-dried for 48 hours to obtain the precursor powder.

[0116] The precursor powder was placed in a tube furnace and treated under the following conditions to obtain high-entropy oxides: the temperature was increased from 25°C to 1100°C at a heating rate of 10°C / min, held for 5 hours, and then cooled to room temperature with the furnace.

[0117] Figure 8 The particle size distribution of the obtained high-entropy oxide is shown, indicating that the particle size of the high-entropy oxide is approximately 2.2 micrometers. Figure 9 The scanning electron microscope image of the prepared high-entropy oxide is shown. Figure 6 The comparison shows that high-entropy oxides synthesized by plasma jet synthesis have smaller particle sizes and higher density compared to high-temperature long-time sintering. This indicates that the plasma jet method has advantages not only in terms of time cost and production efficiency, but also in the preparation of nanomaterials with superior properties.

[0118] The carbon-supported high-entropy oxide prepared in Example 1, the high-entropy oxide prepared in Comparative Example 1, and the high-entropy oxide prepared in Comparative Example 2 (hereinafter referred to as the test material) were subjected to electromagnetic absorption performance tests according to the following procedures:

[0119] The test sample and paraffin were mixed at a mass ratio of 1:1 and pressed into a ring (test sample mass fraction 50 wt.%). The complex dielectric constant of the test sample at room temperature was measured using a vector network analyzer. The dielectric loss tangent was obtained based on the ratio of the imaginary part to the real part of the complex dielectric constant, which reflects the dielectric loss of the prepared carbon-loaded high-entropy oxide. Figure 4The diagram shows a comparison of the dielectric loss tangent of the carbon-loaded high-entropy oxide prepared in Example 1, the high-entropy oxide prepared in Comparative Example 1, and the high-entropy oxide prepared in Comparative Example 2. It can be seen that after the high-entropy oxide in Example 1 is coated with carbon, the dielectric loss is significantly improved by 4 to 5 times.

[0120] Comparative Example 3

[0121] Six metal ion solutions were prepared using water: CrCl3·6H2O, MnCl2·4H2O, FeCl3, CoCl2·6H2O, NiCl2·6H2O, and CuCl2. The concentration of the metal cation in each solution was 0.4 mol / L. Then, 2.5 mL of each solution was added dropwise to 100 mL of deionized water, and the mixture was stirred for 30 min to disperse the ions, resulting in a mixed solution. Finally, 25 mmol of NaOH solution was slowly added to the mixed solution, and the mixture was stirred for another 2 h to obtain a suspension.

[0122] The suspension was filtered, washed with deionized water, and freeze-dried for 48 hours to obtain the precursor powder.

[0123] High-entropy oxides can be obtained by placing the precursor powder directly below the plasma jet and performing plasma jet treatment under the following conditions: the gas used is argon (flow rate of 600 ml / min), the current is 50 A, the treatment time is 3 seconds, the treatment is performed once, and the temperature reaches 1500 K during the plasma jet treatment.

[0124] Figure 10(a) shows a scanning electron microscope (SEM) image of the fabricated high-entropy oxide at a scale of 200 nm, and Figure 10(b) shows a scanning electron microscope (SEM) image of the fabricated high-entropy oxide at a scale of 5 μm; Figure 6 In comparison, it can be seen that as the number of plasma treatments increases, more high-entropy oxide particles precipitate and crystallize on the surface, and the particle size increases with the number of treatments.

[0125] Comparative Example 4

[0126] Six metal ion solutions were prepared using water: CrCl3·6H2O, MnCl2·4H2O, FeCl3, CoCl2·6H2O, NiCl2·6H2O, and CuCl2. The concentration of the metal cation in each solution was 0.4 mol / L. Then, 2.5 mL of each solution was added dropwise to 100 mL of deionized water, and the mixture was stirred for 30 min to disperse the ions, resulting in a mixed solution. Finally, 25 mmol of NaOH solution was slowly added to the mixed solution, and the mixture was stirred for another 2 h to obtain a suspension.

[0127] The suspension was filtered, washed with deionized water, and freeze-dried for 48 hours to obtain the precursor powder.

[0128] High-entropy oxides can be obtained by placing the precursor powder directly below the plasma jet and performing plasma jet treatment under the following conditions: the gas used is argon (flow rate of 600 ml / min), the current is 50 A, the treatment time is 0.1 seconds, the treatment is performed once, and the temperature reaches 1500 K during the plasma jet treatment.

[0129] Figure 11 The scanning electron microscope image of the high-entropy oxide prepared is shown. Compared with Figure 10(b), it can be seen that as the plasma treatment time increases, more high-entropy oxide particles precipitate on the surface and crystallize, and the particle size increases.

[0130] The present invention has been described in detail above with reference to preferred embodiments and exemplary examples. However, it should be noted that these specific embodiments are merely illustrative explanations of the invention and do not constitute any limitation on the scope of protection of the invention. Various improvements, equivalent substitutions, or modifications can be made to the technical content and embodiments of the present invention without departing from the spirit and scope of protection of the invention, and all such modifications fall within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A carbon-supported high-entropy oxide, characterized in that, The carbon-loaded high-entropy oxide has a core-shell structure in which high-entropy oxide is coated with carbon, and the particle size of the high-entropy oxide is between 0.05 and 0.15 μm.

2. The carbon-supported high-entropy oxide according to claim 1, characterized in that, Preferably, based on the total mass of carbon-supported high-entropy oxides, the mass percentage of high-entropy oxides is 3–30 wt%.

3. The carbon-supported high-entropy oxide according to claim 1, characterized in that, The density of the carbon-supported high-entropy oxide is between 2.5 and 4.5 g / cm³. 3 .

4. The carbon-supported high-entropy oxide according to claim 1, characterized in that, The carbon-loaded high-entropy oxide includes at least five metallic elements selected from chromium, manganese, iron, cobalt, nickel, and copper.

5. A method for preparing the carbon-supported high-entropy oxide according to any one of claims 1 to 4, characterized in that, The method comprises: Step 1: Place the metallic phase raw material and carbon material in a solvent to obtain a mixture; Step 2: Pre-treat the mixture to obtain precursor powder; Step 3: The precursor powder is subjected to plasma flow treatment to obtain the carbon-supported high-entropy oxide.

6. The method according to claim 5, characterized in that, In step 1, the metal phase raw material is a soluble metal salt, including at least five of the following: chromium source, manganese source, iron source, cobalt source, nickel source, and copper source.

7. The method according to claim 5, characterized in that, In step 1, the carbon material is mesophase carbon microspheres.

8. The method according to claim 5, characterized in that, In step 2, the pretreatment sequentially includes co-precipitation, filtration, washing, and drying.

9. The method according to claim 8, characterized in that, Step 2 includes the following steps: Step 2-1: Co-precipitate the mixture to obtain a suspension; Step 2-2: The suspension is sequentially filtered, washed and dried to obtain precursor powder.

10. The method according to claim 8 or 9, characterized in that, Co-precipitation is carried out using a precipitant, wherein the precipitant is a strong base, preferably sodium hydroxide or potassium hydroxide.

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