Nitrogen-doped carbon nanotube-wrapped high-entropy alloy composite material, preparation method and application thereof
By encapsulating high-entropy alloy nanoparticles in nitrogen-doped carbon nanotubes, the shortcomings of high-entropy alloy composites in electromagnetic wave absorption and catalytic degradation performance have been overcome, achieving high-efficiency performance improvement for applications in multiple fields.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NORTHWESTERN POLYTECHNICAL UNIV
- Filing Date
- 2026-03-12
- Publication Date
- 2026-06-16
AI Technical Summary
Existing high-entropy alloy composite materials cannot simultaneously meet the requirements of efficient electromagnetic wave absorption by microwave absorbing materials and efficient pollutant degradation by catalytic materials. The difficulty in controlling the composition and structure leads to insufficient performance of the materials in many fields of application.
By coating high-entropy alloy nanoparticles into nitrogen-doped carbon nanotubes, carbon-metal interactions are formed, enhancing the binding force, inhibiting agglomeration, and achieving uniform dispersion of high-entropy alloy particles. Furthermore, the interfacial coupling between carbon nanotubes and high-entropy alloys enhances electron transport, resulting in a multi-component synergistic loss advantage.
A microwave absorbing material with strong absorption, wide bandwidth, light weight and high stability was obtained, which is suitable for the field of electromagnetic protection. At the same time, it significantly increased the exposure of catalytic active sites, realizing the efficient degradation of antibiotics, and is suitable for the field of organic degradation.
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Figure CN122210029A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of high-entropy alloy composite materials technology, such as high-entropy alloy composite materials encapsulated with nitrogen-doped carbon nanotubes, their preparation methods and applications, and particularly to their dual applications in microwave absorbing coatings and wastewater treatment. Background Technology
[0002] With the rapid development of environmental protection needs in modern industry, the research and development of high-performance multifunctional materials has become a cutting-edge hot topic. In the field of electromagnetic wave absorbing coatings, in order to achieve efficient absorption of electromagnetic waves, materials are required to have absorption characteristics of being "thin, light, wide, and strong," while also taking into account corrosion resistance, oxidation resistance, and high-temperature stability. In the field of wastewater treatment, especially for complex wastewater containing heavy metals or organic pollutants, there is an urgent need to develop new catalytic materials that combine efficient catalytic degradation capabilities, stable recycling performance, and easy recyclability.
[0003] High entropy alloys (HEAs), as an emerging multi-principal-element alloy system, have shown potential in both microwave absorption and catalysis due to their unique lattice distortion effect, tunable electromagnetic properties, and excellent chemical stability. In recent years, researchers have attempted to combine HEAs with carbon-based materials (such as graphene and carbon nanotubes) to further enhance their microwave absorption performance; mixing HEA particles with carbon nanotubes can enhance interfacial polarization loss and improve microwave absorption performance; simultaneously, the multi-active-site characteristics of HEAs have also attracted attention for their potential in the catalytic degradation of pollutants.
[0004] However, existing high-entropy alloy composites still have the following limitations: their composition and structure are difficult to control, making it difficult for the obtained materials to simultaneously meet the needs of multiple applications. For example, microwave absorbing materials mainly focus on electromagnetic loss performance, while catalytic materials emphasize the exposure of surface active sites. Currently, there is a lack of a cross-domain, multifunctional material system that can simultaneously integrate efficient electromagnetic wave absorption and high catalytic activity. Summary of the Invention
[0005] To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key / important components or describe the scope of protection of these embodiments, but rather as a prelude to the detailed description that follows.
[0006] This disclosure provides a nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite material, its preparation method, and its application. The high-entropy alloy nanoparticles are encapsulated in nitrogen-doped carbon nanotubes and are uniformly dispersed, effectively suppressing the aggregation of high-entropy alloy nanoparticles and solving the problem that the aggregation of high-entropy alloy particles restricts its microwave absorption performance and catalytic degradation performance.
[0007] In some embodiments, the nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite material has high-entropy alloy particles dispersed in the nitrogen-doped carbon nanotubes, and the high-entropy alloy includes magnetic metal elements.
[0008] In some embodiments, the method for preparing the nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite material includes: preparing a corresponding metal salt according to the metal element in the high-entropy alloy; adding the metal salt to a solvent in an amount equal to the molar ratio of metal atoms; stirring and dissolving to obtain solution A; adding melamine to solution A; mixing to obtain dispersion B; drying dispersion B; and grinding to obtain a powder mixture; and holding the powder mixture at a temperature of 800–1000°C in an inert gas atmosphere for a first preset time, and then cooling to room temperature to obtain the nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite material.
[0009] The nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite material, its preparation method, and its application provided in this disclosure can achieve the following technical effects: In the nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite material of this disclosure, high-entropy alloy particles are encapsulated within nitrogen-doped carbon nanotubes. A carbon-metal (CM) interaction is formed between the carbon nanotubes and the high-entropy alloy. The CM bond bridging enhances the bonding force between the nitrogen-doped carbon nanotubes and the high-entropy alloy, effectively reducing metal dissolution and agglomeration, and effectively inhibiting the agglomeration of high-entropy alloy particles, resulting in uniform dispersion of the high-entropy alloy particles. Simultaneously, a tight interfacial coupling and electronic interaction are formed between the carbon nanotubes and the high-entropy alloy particles, cleverly integrating the multi-component synergistic loss advantage of the high-entropy alloy with the dispersion, protection, and impedance modulation functions of the carbon nanotubes. This yields a microwave absorbing material with strong absorption, wide bandwidth, lightweight, and high stability, suitable for electromagnetic protection. Furthermore, the uniform dispersion of the high-entropy alloy significantly increases the exposure of active sites on the composite material surface. Simultaneously, the CM bond bridging between the carbon nanotubes and the high-entropy alloy forms an electron transport channel, thereby accelerating the interfacial electron transport rate. This enables the efficient activation of dissolved oxygen in the aqueous phase into reactive oxygen species, achieving efficient degradation of antibiotics, suitable for the field of organic degradation.
[0010] The preparation method of this embodiment uses metal salt as metal source, melamine as reducing agent, carbon source and nitrogen source, and generates nitrogen-doped carbon nanotubes through a one-step high-temperature pyrolysis method and coats the carbon nanotubes with high-entropy alloy. The preparation method is simple and easy to operate.
[0011] The above general description and the description below are exemplary and illustrative only and are not intended to limit this application. Attached Figure Description
[0012] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations and drawings do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are shown as similar elements. The drawings are not to be scaled. And wherein: Figure 1 This is a flowchart illustrating a method for preparing a nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite material according to an embodiment of this disclosure. Figure 2a , Figure 2b and Figure 2c SEM spectra of different composite materials prepared in Example 1 provided in this disclosure; Figure 3 These are the XRD patterns of different composite materials prepared in Example 1 of this disclosure; Figure 4 These are Raman spectra of different composite materials prepared in Example 1 of this disclosure; Figure 5 This is the XPS spectrum of the FeCoNiMn / NCNT-800 composite material prepared in Example 1 of this disclosure; Figure 6 This is a TEM image of the FeCoNiMn / NCNT-800 composite material prepared in Example 1 of this disclosure; Figure 7 This is a diagram showing the microwave absorption performance of microwave absorbing coatings of different thicknesses in Embodiment 2 of this disclosure; Figure 8 This is a degradation curve of the composite material for norfloxacin at different pH values in Example 3 of this disclosure; Figure 9 This is a degradation curve of norfloxacin on the composite material in Example 3 of this disclosure under conditions of pH 7 and different inorganic ions or organic matter. Figure 10 This is a degradation curve of the composite material for different organic pollutants in Example 3 of this disclosure. Detailed Implementation
[0013] To provide a more detailed understanding of the features and technical content of the embodiments of this disclosure, the implementation of the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this disclosure. In the following technical description, for ease of explanation, several details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be simplified in their depiction to simplify the drawings.
[0014] Unless otherwise stated, the term "multiple" means two or more.
[0015] In this embodiment of the disclosure, the character " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B means: A or B.
[0016] The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.
[0017] It should be noted that, unless otherwise specified, the embodiments and features described in the present disclosure can be combined with each other.
[0018] This disclosure provides a high-entropy alloy composite material encapsulated in nitrogen-doped carbon nanotubes, wherein the high-entropy alloy particles are dispersed in the nitrogen-doped carbon nanotubes, and the high-entropy alloy includes magnetic metal elements.
[0019] In the nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite material of this disclosure, the high-entropy alloy particles are dispersed in the nitrogen-doped carbon nanotubes (see [link to relevant documentation]). Figure 2b , Figure 2c and Figure 6 As shown in the diagram, high-entropy alloy particles are encapsulated within nitrogen-doped carbon nanotubes. A carbon-metal (CM) interaction forms between the carbon nanotubes and the high-entropy alloy. The CM bonds enhance the bonding force between the nitrogen-doped carbon nanotubes and the high-entropy alloy, preventing component separation and effectively reducing metal dissolution and agglomeration. This effectively inhibits the aggregation or deactivation of the high-entropy alloy particles, ensuring uniform dispersion. Simultaneously, a tight interfacial coupling and electronic interaction are formed between the carbon nanotubes and the high-entropy alloy particles, cleverly combining the multi-component synergistic loss advantages of the high-entropy alloy with the dispersion, protection, and impedance modulation functions of the carbon nanotubes. This results in a microwave absorbing material with strong absorption, wide bandwidth, lightweight, and high stability, suitable for electromagnetic protection applications.
[0020] In the nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite material of this disclosure, synergistic catalysis between active sites is achieved by utilizing the multi-metal redox properties. The coating of nitrogen-doped carbon nanotubes effectively inhibits the agglomeration of the high-entropy alloy during high-temperature pyrolysis and use. The uniform dispersion of the high-entropy alloy significantly increases the exposure of active sites on the surface of the composite material. At the same time, the CM bond bridge between the carbon nanotubes and the high-entropy alloy forms an electron transport channel, thereby accelerating the interfacial electron transport rate. This enables the efficient activation of dissolved oxygen in the aqueous phase into reactive oxygen species, achieving efficient degradation of antibiotics and making it suitable for the field of organic degradation.
[0021] In the nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite material of this disclosure, the "cocktail effect" and significant lattice distortion effect of the high-entropy alloy including magnetic metallic elements endow the composite material with flexibly controllable electromagnetic parameters (dielectric constant, magnetic permeability), and enhance the structural stability and environmental resistance of the composite material. The spatial network structure formed by carbon nanotubes not only protects the high-entropy alloy particles from oxidation and corrosion, but also further optimizes the impedance matching characteristics of the composite material, and provides rich multiple scattering and polarization relaxation interfaces for electromagnetic waves. Together with the magnetic loss mechanism of the high-entropy alloy (eddy current loss, hysteresis loss, etc.), it achieves efficient dissipation of electromagnetic energy. The composite material of this disclosure exhibits strong absorption (low reflection loss value), wide effective absorption bandwidth, and good chemical stability at the matched thickness, significantly improving the microwave absorption performance and service life.
[0022] In the high-entropy alloy composite material of this disclosure, a "core-shell" structure is used, with carbon nanotubes as the "shell" and high-entropy alloys as the "core". The magnetic loss of the high-entropy alloy and the dielectric loss of the carbon nanotubes are stimulated synergistically. Nitrogen doping is used to regulate the surface electron distribution to simultaneously enhance catalytic activity. This balances microwave absorption performance and catalytic performance. It can not only meet the performance requirements of microwave absorbing coatings for broadband strong absorption and resistance to environmental corrosion, but also provide a high-efficiency and recyclable catalytic material for wastewater treatment, realizing the multi-field application of high-entropy alloy composite materials.
[0023] When the nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite material of this disclosure is used as a microwave absorbing material in a microwave absorbing coating, the composite material can form a better bond with the coating components. On the one hand, the abundant chemical bonds in the composite material improve its bonding connection with the coating components, achieving better chemical bonding; on the other hand, the carbon nanotubes and their hollow structure in the composite material increase the bonding surface area and spatial network connection with the coating components, achieving better physical bonding. Furthermore, the carbon nanotube-encapsulated high-entropy alloy improves the potential or optimizes electron transfer through CN-bond bridging, playing a role similar to "cathode protection," and exhibiting improved corrosion resistance compared to ferrites such as carbonyl iron or Fe3O4. Additionally, the structural characteristics of the carbon nanotubes also ensure the film-forming properties of the coating.
[0024] When the nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite material of this disclosure is applied to the efficient degradation of antibiotics, the removal rate of antibiotics exceeds 96% over a wide pH range of 3–11, overcoming the defect of traditional Fenton-like catalysts that are easily deactivated under neutral / alkaline conditions. Furthermore, the coating effect of nitrogen-doped carbon nanotubes improves the cycling stability of the composite material, and the antibiotic degradation rate remains above 90% after seven cycles of reuse.
[0025] In this embodiment of the disclosure, the high-entropy alloy particles include high-entropy alloy nanoparticles. Optionally, the particle size of the high-entropy alloy nanoparticles is less than or equal to 100 nm. It is understood that the particle size of the high-entropy alloy nanoparticles is smaller than the inner diameter of carbon nanotubes.
[0026] Optionally, the particle size of the high-entropy alloy nanoparticles is less than or equal to 50 nm. Optionally, the particle size of the high-entropy alloy nanoparticles is 10–50 nm. Optionally, the particle size is 10–40 nm. Optionally, the particle size is 10–30 nm.
[0027] The composite material in this embodiment includes C=C bonds, C=C bonds, CN bonds, and C O bond, C=O bond and O C=O bonds; where M represents the metal in the high-entropy alloy. The CM bonds indicate an interaction between carbon nanotubes and the high-entropy alloy. The presence of CM bonds effectively enhances the bonding force between carbon nanotubes and the high-entropy alloy, reducing metal dissolution and agglomeration. Furthermore, a tight interfacial coupling and electronic interaction are formed between the carbon nanotubes and the high-entropy alloy particles, cleverly integrating the multi-component synergistic loss advantages of the high-entropy alloy with the dispersion, protection, and impedance regulation functions of carbon nanotubes. This results in a microwave absorbing material with strong absorption, wide bandwidth, lightweight, and high stability, suitable for electromagnetic protection. It also forms an electron transport channel, thereby accelerating the interfacial electron transport rate and achieving efficient degradation of antibiotics. The CN bonds indicate that nitrogen has been successfully doped into the carbon nanotubes, which is significant for improving the electron transport rate and accelerating the adsorption and activation of molecular oxygen and reactants. Additionally, the incorporation of nitrogen atoms introduces defects and dipoles into the carbon lattice. These polar centers undergo significant polarization relaxation under the action of an alternating electromagnetic field, converting electromagnetic energy into heat energy for dissipation. Meanwhile, moderate nitrogen doping can effectively regulate the conductivity and dielectric constant of the carbon matrix, optimizing its impedance matching characteristics and making it easier for electromagnetic waves to penetrate the material. The introduced CN bonds and related defects can serve as additional scattering centers, synergizing with the magnetic losses generated by the high-entropy alloy magnetic components to jointly enhance the composite material's microwave absorption performance over a wide frequency range. Therefore, CN bonds also provide the structural basis for this composite material as a microwave absorbing material.
[0028] In some embodiments, the magnetic metallic element included in the high-entropy alloy is selected from one or more of Fe, Co, Ni and Cr.
[0029] Optionally, the magnetic metallic elements include Fe and Ni. The high-entropy alloy in this embodiment is an iron-nickel-based high-entropy alloy.
[0030] Optionally, the magnetic metallic elements include Fe, Co, and Ni. In this embodiment, the high-entropy alloy is an iron-cobalt-nickel based high-entropy alloy.
[0031] In some embodiments, the high-entropy alloy further includes one or more of Cu, Mn, and Zn. The specific choice depends on the actual requirements.
[0032] In some embodiments, the high-entropy alloy is a quaternary high-entropy alloy comprising Fe, Co, Ni, and Mn.
[0033] Combination Figure 1 As shown in the embodiments of this disclosure, a method for preparing a high-entropy alloy composite material encapsulated by nitrogen-doped carbon nanotubes is provided, comprising the following steps: S10. Prepare corresponding metal salts based on the metal elements in the high-entropy alloy. Add the metal salts to the solvent in an equal molar ratio of the metal elements, stir to dissolve, and obtain solution A. The metal elements in the high-entropy alloy include magnetic metal elements. The types of metal elements in the high-entropy alloy are determined according to actual needs and are not limited.
[0034] S20. Add melamine to solution A and mix well to obtain dispersion B. In this step S20, the mixing method is not limited; for example, stirring, or optionally, magnetic stirring. The stirring time is not limited, but the goal is to uniformly mix the melamine into solution A to obtain dispersion B.
[0035] S30. After drying the dispersion B, grind it to obtain a powder mixture.
[0036] S40. The powder mixture is kept at a temperature of 800-1000°C for a first preset time in an inert gas atmosphere, and then cooled to room temperature to obtain a high-entropy alloy composite material encapsulated by nitrogen-doped carbon nanotubes.
[0037] In the preparation method of this disclosure, a metal salt is used as the metal source, and melamine is used as the reducing agent, carbon source, and nitrogen source. Nitrogen-doped carbon nanotubes are generated through a one-step high-temperature pyrolysis method, and a high-entropy alloy is coated onto the carbon nanotubes. The preparation method is simple and easy to operate; the nitrogen-doped carbon nanotube-coated high-entropy alloy composite material can be obtained by uniformly mixing the raw materials and then performing a one-step high-temperature pyrolysis. Combined with... Figure 6 As shown, high-entropy alloy nanoparticles are coated within nitrogen-doped carbon nanotubes. The particle size of the high-entropy alloy nanoparticles is less than or equal to 50 nm.
[0038] The preparation method of this embodiment adds melamine as a nitrogen source and a carbon source, introduces nitrogen species on carbon nanotubes, and at the same time, melamine provides a reducing atmosphere as a carbon source during high-temperature pyrolysis, so that the metal reduction is more complete.
[0039] In step S10, the metal salt and solvent are not limited and are determined according to the actual situation. In some embodiments, the metal salt is a soluble salt, which can be soluble in water or in an organic solvent. Therefore, the solvent includes water and / or other solvents.
[0040] In some embodiments, the magnetic metallic element included in the high-entropy alloy is selected from one or more of Fe, Co, Ni and Cr.
[0041] Alternatively, the metal salts of Fe include Fe(NO3)3•9H2O, Fe(CH3COO)3•4H2O, or FeCl3•6H2O.
[0042] Alternatively, the metal salts of Co include Co(NO3)2·6H2O, Co(CH3COO)2·4H2O, or CoCl2·6H2O.
[0043] Alternatively, the metal salts of Ni include Ni(NO3)2·6H2O, Ni(CH3COO)2·4H2O, or NiCl2·6H2O.
[0044] Alternatively, the metal salts of Cr include Ni(NO3)3·9H2O or CrCl3·6H2O.
[0045] In some embodiments, in step S10, the high-entropy alloy further includes one or more of Cu, Mn, and Zn.
[0046] Alternatively, the metal salts of Cu include Cu(NO3)2·3H2O, Cu(CH3COO)2·H2O, or CuCl2·2H2O.
[0047] Alternatively, the metal salts of Zn include Zn(NO3)2·6H2O, Zn(CH3COO)2·2H2O or ZnCl2·6H2O.
[0048] Alternatively, the metal salts of Mn include Mn(NO3)2·6H2O, Mn(CH3COO)2·4H2O or MnCl2·4H2O.
[0049] In some embodiments, in step S10, metal salts are added to the solvent in an equal molar ratio of metal atoms, wherein the ratio of the amount of metal atoms of one metal salt to the solvent is 1–2 mmol: 10–20 mL. In this embodiment, each metal atom is added in an equal molar ratio, that is, the ratio of the amount of each metal atom to the solvent is the same and is within 1–2 mmol: 10–20 mL. That is, in solution A, the molar concentration of each metal atom of the metal salt is approximately 0.05–0.2 mol / L.
[0050] Optionally, in step S10, the ratio of the amount of metal atoms of one of the metal salts to the solvent is 1 mmol: 10–15 mL. That is, in solution A, the molar concentration of metal atoms of each metal salt is approximately 0.07–0.15 mol / L.
[0051] Optionally, in step S10, the ratio of the amount of metal atoms of one of the metal salts to the solvent is 2 mmol: 15–20 mL. That is, in solution A, the molar concentration of metal atoms of each metal salt is approximately 0.1–0.13 mol / L.
[0052] In step S10, the stirring and dissolving time is not limited, as long as the metal salts are dissolved and mixed evenly.
[0053] In some embodiments, in step S20, the molar ratio of the added melamine to the metal atoms of a metal salt is 8–15:1. This ratio ensures the formation of a structurally complete carbon nanotube coating layer with appropriate nitrogen doping, while also achieving sufficient reduction and uniform dispersion of the metal particles, thereby obtaining a highly active and stable nitrogen-doped carbon nanotube-coated high-entropy alloy composite material.
[0054] Optionally, in step S20, the molar ratio of the added melamine to the metal atoms of a metal salt is 8–13:1. Optionally, the molar ratio is 8–12:1. Optionally, the molar ratio is 9–11:1. Optionally, the molar ratio is 10:1.
[0055] In some embodiments, in step S10, the solvent includes a polar solvent. The solvent is capable of dissolving the metal salts to form a metal salt solution. Optionally, the polar solvent includes anhydrous ethanol and water.
[0056] In step S30, the dispersion B is dried to obtain a solid mixture of precursors in which each metal salt and melamine are evenly mixed, which facilitates subsequent high-temperature pyrolysis. At the same time, drying can prevent the precursor powder mixture from splashing during high-temperature pyrolysis, thus avoiding material loss and uneven mixing.
[0057] In some embodiments, step S30, drying the dispersion B, includes drying the dispersion B at a drying temperature of 50–80°C. In this embodiment, the drying time is not limited and is determined according to the actual situation.
[0058] Optionally, the drying temperature is 55–75°C. Optionally, the drying temperature is 60–70°C. Optionally, the drying temperature is 65°C.
[0059] Optionally, in step S30, drying is carried out in a forced-air drying oven.
[0060] Step S40 of this embodiment is to obtain a nitrogen-doped carbon nanotube-coated high-entropy alloy composite material by high-temperature pyrolysis of a powder mixture containing multiple metals. The high-temperature pyrolysis temperature is controlled in the range of 800 to 1000°C. This pyrolysis temperature enables the metal salt to be pyrolyzed at high temperature, and a high-purity high-entropy alloy phase with a face-centered cubic (FCC) structure is formed under the reduction action of melamine. At the same time, carbonization is sufficient to form a carbon nanotube structure.
[0061] In some embodiments, step S40, holding the powder mixture at a temperature of 700–1000°C in an inert gas atmosphere for a first preset time, includes: placing the powder mixture in an inert gas atmosphere, heating it to 700–1000°C at a rate of 3–8°C / min, and holding it at that temperature for the first preset time. In this embodiment, by controlling the heating rate, it is possible to better ensure that all parts of the sample can uniformly reach the required temperature, so that the high-temperature reduction pyrolysis of the metal salt can fully obtain high-entropy alloy nanoparticles, the carbonization of melamine can fully obtain carbon nanotubes, and the high-entropy alloy nanoparticles are encapsulated within the carbon nanotubes. The first preset time is not limited and is determined according to the actual situation.
[0062] Optionally, the temperature is raised to 700-1000°C at a rate of 4-6°C / min and held for a first preset time.
[0063] Optionally, the temperature is raised to 700-1000°C at a rate of 5°C / min and held for a first preset time.
[0064] Optionally, the powder mixture is held at a temperature of 800–1000°C in an inert gas atmosphere for a first preset time. Optionally, the powder mixture is held at a temperature of 700–900°C in an inert gas atmosphere for a first preset time. Optionally, the powder mixture is held at a temperature of 750–850°C in an inert gas atmosphere for a first preset time. By optimizing the high-temperature pyrolysis temperature, a high-entropy alloy composite material with better and more uniform morphology is obtained.
[0065] Optionally, in step S40, the inert gas includes nitrogen or argon.
[0066] Optionally, in step S40, the first preset duration is 1 to 3 hours.
[0067] Optionally, in step S40, the first preset duration is 2 hours.
[0068] In some embodiments, step S40, cooling to room temperature includes: cooling down to room temperature at a rate of 3 to 8 °C / min.
[0069] Optionally, in step S40, cooling to room temperature includes cooling down to room temperature at a rate of 4 to 6 °C / min.
[0070] Optionally, in step S40, cooling to room temperature includes: cooling down to room temperature at a rate of 5°C / min.
[0071] This disclosure also provides the application of the nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite material prepared by the preparation method of the nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite material of any of the foregoing embodiments as a microwave absorbing material in microwave absorbing coatings, or as a catalyst in the degradation of organic pollutants in water.
[0072] In the application of this disclosure embodiment, in the high-entropy alloy composite material wrapped with nitrogen-doped carbon nanotubes, the high-entropy alloy particles are uniformly dispersed, and a tight interfacial coupling and electronic interaction are formed between the carbon nanotubes and the high-entropy alloy particles. This cleverly integrates the multi-component synergistic loss advantage of high-entropy alloys with the dispersion, protection, and impedance regulation functions of carbon nanotubes, resulting in a microwave absorbing material with strong absorption, wide bandwidth, lightweight, and high stability, which is suitable for the field of electromagnetic protection.
[0073] Meanwhile, the coating of nitrogen-doped carbon nanotubes effectively inhibits the agglomeration of high-entropy alloys during high-temperature pyrolysis and use. The uniform dispersion of the high-entropy alloy significantly increases the exposure of active sites on the composite material surface. Furthermore, the CM bond bridge between the carbon nanotubes and the high-entropy alloy forms an electron transport channel, thereby accelerating the interfacial electron transport rate. This enables the efficient activation of dissolved oxygen in the aqueous phase into reactive oxygen species, achieving efficient degradation of antibiotics and making it suitable for organic degradation applications. It also exhibits good versatility and a wide range of applications, achieving antibiotic removal rates exceeding 96% within a wide pH range of 3–11, overcoming the deficiency of traditional Fenton-like catalysts that are prone to deactivation under neutral / alkaline conditions. In addition, the coating of nitrogen-doped carbon nanotubes enhances the cycling stability of the composite material; after seven cycles of reuse, the antibiotic degradation rate remains above 90%.
[0074] In some embodiments, the mass percentage of the high-entropy alloy composite material encapsulated by nitrogen-doped carbon nanotubes in the absorbing coating is 40% to 70%. It is understood that the absorbing coating is obtained by applying an absorbing paint. Therefore, in the absorbing paint, besides the high-entropy alloy composite material, the remaining components are other conventional components constituting the paint, such as resin, filler, pigment, defoamer, leveling agent, functional additives, solvent, etc., which can be selected and determined according to the actual situation. The absorbing coating of this embodiment includes the high-entropy alloy composite material encapsulated by nitrogen-doped carbon nanotubes from any of the foregoing embodiments, giving the absorbing coating absorbing wave characteristics, making it suitable for the field of electromagnetic protection.
[0075] Optionally, a microwave absorbing coating is used to coat and form the aforementioned microwave absorbing coating, comprising a siloxane resin in a weight ratio of 1:(0.8-1.5):(0.5-0.8):(0.3-0.5), a high-entropy alloy composite material encapsulated with nitrogen-doped carbon nanotubes from any of the preceding embodiments, inorganic fillers, and additives.
[0076] In this embodiment, the microwave absorbing coating uses a highly cross-linked methyl-phenyl (or acrylic acid modified) polysiloxane prepolymer, which exhibits properties such as room temperature curing, ultra-high temperature resistance (650–1300 °C), and low VOCs. Optionally, the siloxane resin used is from Kaifeng Quark New Materials Co., Ltd.
[0077] Optionally, the inorganic filler includes bentonite, fumed silica, alumina fiber powder, mica powder, talc powder, and 50% copper chromium black paste. The weight ratios of the alumina fiber powder, mica powder, talc powder, 50% copper chromium black paste, bentonite, and fumed silica in the inorganic filler are (1-2):1:1:0.5:0.1:0.1, respectively.
[0078] Optionally, the additives include PM solvent, leveling agent, coupling agent, and defoamer, wherein the weight ratio of PM solvent, leveling agent, coupling agent, and defoamer in the additives is 10–20:0.2–0.5:3–5:1, respectively. In this embodiment, the PM solvent is propylene glycol methyl ether. The leveling agent, coupling agent, and defoamer are not limited and are determined according to the actual situation.
[0079] Alternatively, the coupling agent may include phthalate catalysts.
[0080] The following specific embodiments illustrate the nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite materials, their preparation methods, and applications, to more clearly explain the technical problems solved, technical solutions, and beneficial effects of this application. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications.
[0081] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.
[0082] Example 1: Nitrogen-doped carbon nanotube-encapsulated iron-cobalt-nickel-based high-entropy alloy composite material A method for preparing a nitrogen-doped carbon nanotube-encapsulated iron-cobalt-nickel-based high-entropy alloy composite material includes the following steps: S101. Dissolve Fe(NO3)3·9H2O, Co(NO3)2·6H2O, Ni(NO3)2·6H2O, and Mn(CH3CO2)2·4H2O in deionized water in equimolar amounts, and stir until dissolved (e.g., for 30 min) to obtain solution A. The ratio of the amount of each metal salt to anhydrous ethanol is 1 mmol: 10 mL.
[0083] S201. Melamine is added to solution A and magnetically stirred for 30 minutes to obtain dispersion B. The molar ratio of melamine to the metal atoms of a metal salt is 10:1.
[0084] S301. Place dispersion B in a forced-air drying oven and dry at a drying temperature of 80°C (e.g., for 12 hours) to obtain a powder mixture.
[0085] S401. Place the powder mixture into a tube furnace, heat it to 700-1000℃ at a rate of 5℃ / min in a nitrogen inert gas atmosphere and hold it for 2 hours, then cool it to room temperature to obtain a nitrogen-doped carbon nanotube-encapsulated iron-cobalt-nickel-based high-entropy alloy composite material.
[0086] The nitrogen-doped carbon nanotube-encapsulated iron-cobalt-nickel-based high-entropy alloy composite material prepared in Example 1 is a black powder, and the iron-cobalt-nickel-based high-entropy alloy nanoparticles are encapsulated in nitrogen-doped carbon nanotubes, wherein the particle size of the iron-cobalt-nickel-based high-entropy alloy nanoparticles is less than or equal to 100 nm. The high-entropy alloy is a high-entropy alloy including Fe, Co, Ni and Mn.
[0087] In this embodiment 1, by adjusting step S401, the temperature is raised to 800℃ and 1000℃ respectively, and composite materials obtained at different pyrolysis temperatures are obtained, namely composite material sample (b) (denoted as FeCoNiMn / NCNT-800) and composite material sample (c) (denoted as FeCoNiMn / NCNT-1000).
[0088] Figure 2a , Figure 2b and Figure 2cThe SEM spectra of FeCoNiMn / NCNT-600 (sample (a) of Comparative Example 1), FeCoNiMn / NCNT-800 (sample (b)), and FeCoNiMn / NCNT-1000 (sample (c)) are shown, respectively. It can be seen that the comparative sample prepared by pyrolysis at 600℃ contains many spherical particles, exhibiting severe agglomeration and incomplete formation of carbon nanotubes. This is due to the low pyrolysis temperature and insufficient carbonization. The composite materials prepared at 800℃ and 1000℃ formed carbon nanotube structures with uniform structure and regular morphology. Among them, the composite material obtained at 800℃ has a more uniform structure, more regular morphology, and better carbon nanotube structure.
[0089] Figure 3 The XRD patterns are shown for FeCoNiMn / NCNT-600, FeCoNiMn / NCNT-800, and FeCoNiMn / NCNT-1000, as well as Co / NCNT-800 (Comparative Example 2). Comparison with standard XRD cards reveals that all maintain the same face-centered cubic (FCC) structure as Co, rather than the characteristic diffraction peaks of individual Fe, Co, Ni, and Mn. This indicates that different metal salts, under high-temperature pyrolysis and melamine reduction, form a high-purity, high-entropy alloy phase with an FCC structure. Furthermore, the XRD diffraction peaks shift towards lower angles (2θ decreases). This is because the forced mutual solubility of different atomic sizes induces lattice distortion, resulting in an overall increase in the lattice constant, i.e., an increase in the interplanar spacing d. With increasing pyrolysis temperature, the intensity of the characteristic diffraction peaks increases, indicating that high temperature is beneficial for improving the crystallinity of the material. Comparing the XRD patterns of Co / NCNT-800, it is shown that the XRD diffraction peaks of the high-entropy alloy formed in Example 2 have shifted, indicating that the quaternary alloy has undergone lattice distortion, further demonstrating the formation of a high-entropy alloy.
[0090] Figure 4 The images show the Raman spectra of FeCoNiMn / NCNT-600, FeCoNiMn / NCNT-800, and FeCoNiMn / NCNT-1000. D and G peaks appeared in all samples generated at different pyrolysis temperatures. Generally, a higher D-to-G peak ratio (ID / IG) indicates a higher degree of graphitization in the carbon material. A higher degree of graphitization indicates a higher electron transfer rate, which accelerates the activation of molecular oxygen. It can be seen that the ID / IG ratio of the samples gradually increases with increasing pyrolysis temperature.
[0091] Figure 5The image shows the XPS spectrum of carbon in the FeCoNiMn / NCNT-800 composite material. Peak fitting results indicate that the peaks at binding energies of 283.6 eV, 284.6 eV, 285.8 eV, 286.2 eV, 287.3 eV, and 288.8 eV are assigned to CM, C=C, CN, and C, respectively. O, C=O and O C=O bonds. The presence of C=O bonds indicates an interaction between carbon nanotubes and high-entropy alloys, effectively enhancing their bonding strength, reducing metal dissolution and agglomeration, and forming electron transport channels to accelerate interfacial electron transport rates, thus achieving efficient antibiotic degradation. The presence of CN bonds demonstrates successful nitrogen doping into carbon nanotubes, which is significant for improving electron transport rates and accelerating the adsorption and activation of molecular oxygen and reactants. Furthermore, nitrogen doping introduces defects and dipoles into the carbon lattice. These polar centers undergo significant polarization relaxation under alternating electromagnetic fields, converting electromagnetic energy into heat energy for dissipation. Simultaneously, moderate nitrogen doping effectively modulates the conductivity and dielectric constant of the carbon matrix, optimizing its impedance matching characteristics and making it easier for electromagnetic waves to penetrate the material. The introduced CN bonds and related defects act as additional scattering centers, synergistically enhancing the composite material's microwave absorption performance over a wide frequency range, in conjunction with the magnetic losses generated by the high-entropy alloy's magnetic components. Therefore, CN bonds also provide the structural basis for this composite material as a microwave absorbing material.
[0092] Figure 6 This is a TEM image of the FeCoNiMn / NCNT-800 composite material. Figure 6 Images (a) and (b) show that the high-entropy alloy particles have an octahedral structure and are uniformly dispersed in the carbon nanotubes without obvious agglomeration. Image (c) shows selected area electron diffraction patterns where the diffraction rings belong to the (111), (200), and (220) crystal planes of the FCC phase structure. Image (d) clearly shows the lattice fringes of the sample with spacings of 2.057 Å and 1.787 Å, corresponding to the (111) and (200) crystal planes of the FCC structure, respectively. These characterization results are consistent with the XRD results. In image (e), analysis of the elemental distribution in the sample revealed that Fe, Co, Ni, and Mn are uniformly dispersed without elemental segregation. Nitrogen is uniformly dispersed in the carbon nanotubes. This result further confirms the successful preparation of nitrogen-doped carbon nanotube-coated high-entropy alloy composite materials.
[0093] Comparative Example 1 Unlike Example 1, in step S401 the temperature was raised to 600°C, while the other steps and parameters remained unchanged, resulting in a catalyst comparison sample (a), denoted as FeCoNiMn / NCNT-600.
[0094] Comparative Example 2 A method for preparing a Co-carbon nanotube composite material includes the following steps: 4 mmol of Co(NO3)2·6H2O is added to 10 mL of anhydrous ethanol and magnetically stirred until completely dissolved to form a homogeneous solution. Then, 10 mmol of melamine is added to the resulting solution, and magnetic stirring continues for 30 min. The resulting dispersion is placed in a forced-air drying oven and dried at 65℃ for 12 h to obtain a brownish-red powder. After grinding, the powder is placed in a tube furnace, nitrogen gas is introduced, and it is pyrolyzed at 800℃ for 2 h with a heating and cooling rate of 5℃ / min to obtain the Co-carbon nanotube composite material, denoted as Co / NCNT-800.
[0095] Comparative Example 3 A hybrid material of FeCoNiMn high-entropy alloy and carbon nanotubes is obtained by physically mixing FeCoNiMn high-entropy alloy and carbon nanotubes at a mass ratio of 1:1, resulting in a comparative hybrid material.
[0096] The FeCoNiMn high-entropy alloy was prepared as follows: Fe(NO3)3·9H2O, Co(NO3)2·6H2O, Ni(NO3)2·6H2O, and Mn(CH3CO2)2·4H2O were dissolved in deionized water in an equimolar ratio and stirred for 30 min to obtain solution A. The molar ratio of each metal salt to anhydrous ethanol was 1 mmol: 10 mL. Solution A was placed in a hydrothermal reactor and reacted at 150 °C for 24 h to obtain a reaction solution. The reaction solution was centrifuged to obtain a precipitate, which was washed and then vacuum dried at 80 °C for 8 h to obtain a quaternary metal precursor. The quaternary metal precursor was placed in a ceramic boat and then placed in a tube furnace. The furnace was heated to 800 °C at a rate of 5 °C / min and held for 2 h in an argon inert gas atmosphere, then cooled to room temperature to obtain the FeCoNiMn high-entropy alloy.
[0097] Carbon nanotubes are prepared by the following method: melamine is pyrolyzed at 800℃, releasing gaseous small molecule fragments containing carbon and nitrogen. These fragments undergo catalytic decomposition and recombination under the action of metal catalyst nanoparticles or metal salts, resulting in the dissolution and precipitation of carbon atoms to form carbon nanotubes. Because melamine contains nitrogen, the carbon nanotubes exhibit a certain degree of nitrogen doping.
[0098] Example 2 The preparation method of nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite material and its application as a microwave absorbing material in microwave absorbing coating.
[0099] A microwave absorbing coating is obtained by applying the following microwave absorbing paint. The microwave absorbing paint, by weight, comprises 40 parts of siloxane resin, 80 parts of FeCoNiMn / NCNT-800 sample (b) from Example 1, 10-20 parts of aluminosilicate fiber powder, 10 parts of mica powder, 10 parts of talc powder, 5 parts of 50% copper chromium black paste, 1 part of bentonite, 1 part of fumed silica, 0.3 parts of leveling agent, 1 part of defoamer, 4 parts of coupling agent (phthalate catalyst), and 15 parts of PM solvent.
[0100] The microwave absorbing coating of this embodiment 2 is obtained through the following steps: First, siloxane resin and 50% copper chromium black paste are mixed. Then, aluminum silicate fiber powder, mica powder, talc powder, bentonite, fumed silica, leveling agent, defoamer and PM solvent are added while stirring. After stirring and dispersing evenly, FeCoNiMn / NCNT-800 sample (b) and coupling agent are added and mixed evenly.
[0101] The microwave absorbing coating of Example 2 was applied to a substrate to obtain microwave absorbing coatings of different thicknesses. Specifically, six different thicknesses of microwave absorbing coatings were obtained: microwave absorbing coating I with a thickness of 1.5 mm, microwave absorbing coating II with a thickness of 2 mm, microwave absorbing coating III with a thickness of 3 mm, microwave absorbing coating IV with a thickness of 3.5 mm, microwave absorbing coating V with a thickness of 4 mm, and microwave absorbing coating VI with a thickness of 5 mm.
[0102] Example 3 The preparation method of nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite material and its application as a microwave absorbing material in microwave absorbing coating.
[0103] A microwave absorbing coating is obtained by applying the following microwave absorbing paint. The microwave absorbing paint, by weight, comprises 20 parts of siloxane resin, 100 parts of FeCoNiMn / NCNT-800 sample (b) from Example 1, 10 parts of aluminosilicate fiber powder, 5 parts of mica powder, 5 parts of talc powder, 3 parts of 50% copper chromium black paste, 0.5 parts of bentonite, 0.5 parts of fumed silica, 0.2 parts of leveling agent, 0.5 parts of defoamer, 2 parts of coupling agent (phthalate catalyst), and 8 parts of PM solvent.
[0104] The preparation steps of the microwave absorbing coating in Example 3 are the same as those in Example 2.
[0105] The microwave absorbing coating of Example 3 was applied to a substrate to obtain microwave absorbing coatings of different thicknesses. Specifically, three microwave absorbing coatings of different thicknesses were obtained: microwave absorbing coating A with a thickness of 2 mm, microwave absorbing coating B with a thickness of 3.5 mm, and microwave absorbing coating C with a thickness of 4 mm.
[0106] Example 4 The preparation method of nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite material and its application as a microwave absorbing material in microwave absorbing coating.
[0107] A microwave absorbing coating is obtained by applying the following microwave absorbing paint. The microwave absorbing paint, by weight, comprises 20 parts of siloxane resin, 60 parts of FeCoNiMn / NCNT-800 sample (b) from Example 1, 10 parts of aluminosilicate fiber powder, 5 parts of mica powder, 5 parts of talc powder, 3 parts of 50% copper chromium black paste, 0.5 parts of bentonite, 0.5 parts of fumed silica, 0.2 parts of leveling agent, 0.5 parts of defoamer, 2 parts of coupling agent (phthalate catalyst), and 8 parts of PM solvent.
[0108] The preparation steps of the microwave absorbing coating in Example 4 are the same as those in Example 2.
[0109] The microwave absorbing coating of Example 4 was applied to a substrate to obtain microwave absorbing coatings of different thicknesses. Specifically, three microwave absorbing coatings of different thicknesses were obtained: microwave absorbing coating D with a thickness of 2 mm, microwave absorbing coating E with a thickness of 3.5 mm, and microwave absorbing coating F with a thickness of 4 mm.
[0110] Comparative Example 4 A coating, differing from Example 2 in that it uses iron tetroxide powder instead of FeCoNiMn / NCNT-800 in Example 1, while the remaining components and amounts are the same as in Example 2. This coating of Comparative Example 4 is designated as Comparative Coating I.
[0111] Contrast coating I was applied to the substrate to obtain three contrast coatings with different thicknesses of 2 mm, 3.5 mm and 4 mm, respectively, which were denoted as contrast coating I, contrast coating II and contrast coating III.
[0112] Comparative Example 5 A coating, differing from Example 2, uses the comparative mixture of Comparative Example 3 instead of FeCoNiMn / NCNT-800 in Example 1, while the remaining components and amounts are the same as in Example 2. This coating of Comparative Example 5 is designated as Comparative Coating II.
[0113] Contrast coating II was applied to the substrate to obtain three contrast coatings with different thicknesses of 2 mm, 3.5 mm and 4 mm, respectively, which were denoted as contrast coating IV, contrast coating V and contrast coating VI.
[0114] The following performance tests were conducted on the six microwave absorbing coatings of different thicknesses in Example 2, the three microwave absorbing coatings of different thicknesses in Example 3, the three microwave absorbing coatings of different thicknesses in Example 4, and the six comparative coatings in Comparative Examples 4 and 5.
[0115] (a) Wave absorption performance test The reflectivity of radar absorbing materials (RAM) of Example 2 was tested in the range of 2–18 GHz using the standard GJB 2038A-2011 radar absorbing material reflectivity test. The results are as follows: Figure 7 The diagram shows the absorption performance of absorbing coatings of different thicknesses. It can be seen that when the absorption sample has R < -10dB, the absorption rate as an absorbing material has reached 90%, which is practically significant. The highest absorption value is achieved when the thickness of the absorbing coating is 3.5mm, reaching a peak of -15dB at around 10GHz. At this point, the bandwidth (i.e., the effective absorption bandwidth) of R < -10dB is 4.1GHz, and the absorption bandwidth is the widest.
[0116] (ii) Weather resistance test Weather resistance was tested using QUVB, and accelerated aging was performed using a UVB-313 UV lamp. The test results for the six absorbing coatings of Example 2 and the six control coatings of Comparative Example 4 and Comparative Example 5 are shown in Table 1.
[0117] Table 1
[0118] (iii) Bonding strength test The adhesion, i.e. the bond strength, of the coating was tested by pull-out test, and the test results of the six microwave absorbing coatings of Example 2 and the six comparative coatings of Comparative Example 4 and Comparative Example 5 are shown in Table 2.
[0119] Table 2
[0120] (iv) Corrosion resistance test Salt spray test Neutral salt spray resistance test method: According to the national standard GB / T 1771-2007 "Paints and varnishes, determination of neutral salt spray resistance", the test results of the 6 microwave absorbing coatings of Example 2 and the 6 comparative coatings of Comparative Example 4 and Comparative Example 5 are shown in Table 3.
[0121] Table 3
[0122] As shown in Tables 1, 2, and 3, compared to the coatings of traditional iron oxide ferrite microwave absorbing materials and the coatings of the comparative mixed materials in Comparative Example 3, the coating of sample (b) containing FeCoNiMn / NCNT-800 from Example 1 exhibits better weather resistance, corrosion resistance, and adhesion strength. This indicates that the composite material of the present disclosure has better stability, corrosion resistance, and UV aging resistance; and that the composite material can form a better bond with the coating components. On the one hand, the abundant chemical bonds in the composite material improve its bonding connection with the coating components, achieving better chemical bonding; on the other hand, the carbon nanotubes and their hollow structure in the composite material increase the bonding surface area and spatial network connection with the coating components, achieving better physical bonding.
[0123] Example 5 Application of nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composites as catalysts in the degradation of organic pollutants in water.
[0124] Application Experiment 1: A norfloxacin (NOR) solution with an initial concentration C0 of 20 mg / L was used as the degradation solution. The pH of the degradation solution was adjusted with 0.1 mol / L NaOH or 0.1 mol / L H2SO4 to obtain five degradation solutions with pH values of 3, 5, 7, 9, and 11. The FeCoNiMn / NCNT-800 composite material from Example 1 was added to each of these five degradation solutions, and the mixture was stirred, with timing starting at the moment of addition. The dosage of the FeCoNiMn / NCNT-800 composite material was 1 g / L. During the degradation process, 3 mL of the degradation solution was taken at regular intervals, filtered through a 0.22 μm filter membrane to remove the composite material, and placed in a 1 cm quartz cuvette. The absorbance was measured using a UV-Vis spectrophotometer to determine the concentration C of norfloxacin. The results were as follows: Figure 8 The graph shows the degradation curves of norfloxacin at different pH values, where the vertical axis represents C / C0. A better removal effect corresponds to a smaller C value, and consequently a smaller C / C0 ratio. The degradation rate / removal rate is (1 - C / C0) × 100%. Therefore, a better removal effect results in a higher degradation rate / removal rate.
[0125] pass Figure 8 It can be seen that pH value has no significant effect on degradation performance, exhibiting excellent degradation effects within a pH range of 3–11, with norfloxacin removal rates exceeding 96% within 40 minutes. Under acidic conditions, the degradation rate reaches 99.6% at pH 3 and 99.2% at pH 5; under neutral conditions, the degradation rate reaches 98.7% at pH 7; and under alkaline conditions, the degradation rate reaches 97.8% at pH 9 and 96.3% at pH 11. Therefore, the composite material in Example 1 overcomes the defect of traditional Fenton-like catalysts being easily deactivated under neutral / alkaline conditions.
[0126] Application Experiment 2: A norfloxacin (NOR) solution with an initial concentration C0 of 20 mg / L was used as the degradation solution. Different inorganic ions and organic matter were added to it, and the pH was adjusted to 7 to obtain multiple neutral degradation solutions containing different inorganic ions or organic matter. The FeCoNiMn / NCNT-800 composite material from Example 1 was added to each of these neutral degradation solutions, and the mixture was stirred, with timing starting at the moment of addition. The dosage of the FeCoNiMn / NCNT-800 composite material was 1 g / L. Similar to Application Experiment 2, the concentration C of norfloxacin was measured at regular intervals. Results were obtained as follows... Figure 9 The graph shows the removal efficiency of the composite material for norfloxacin under different inorganic ion or organic matter conditions at pH 7, with the vertical axis representing C / C0. A better removal efficiency corresponds to a smaller C and thus a smaller C / C0. The degradation rate / removal rate is (1 - C / C0) × 100%. Therefore, a better removal efficiency results in a higher degradation rate / removal rate.
[0127] Depend on Figure 9 It is evident that the composite material exhibits strong resistance to ion interference. Without the addition of ions and organic matter, the removal rate of NOR is 98.7% (Control curve). 20 mmol Cl - It accelerated the removal rate of NOR, achieving 100% removal within 40 minutes, because ·Cl and ·Cl2 were formed in the solution. - These reactive species, in synergistic effect with reactive oxygen species, promote the removal of NOR. In contrast, 20 mmol of H₂PO₄... - NO3 - HCO3 - The degradation effect was somewhat inhibited, with removal rates decreasing to 96.8%, 95.7%, and 94.6%, respectively. This is because inorganic ions have a quenching effect on active species. The inhibitory effect of 20 mg / L humic acid (HA) was more pronounced, with the removal rate decreasing to 87.1% within 40 min. This is because HA contains abundant functional groups on its surface, which easily adsorb onto the catalyst surface, covering the active sites and thus preventing it from functioning. Overall, the FeCoNiMn / NCNT-800 catalyst exhibits strong anti-interference ability and has significant application prospects in complex aquatic environments.
[0128] Application Experiment 3: Several common organic pollutants found in the environment were selected for the experiment, including norfloxacin (NOR), the organic dye rhodamine B (RhB), methyl orange (MO), methylene blue (MB), and tetracycline hydrochloride (TCH). Degradation solutions for the above five different organic pollutants were prepared with an initial concentration C0 of 20 mg / L, and the pH of each solution was adjusted to 7. Then, the FeCoNiMn / NCNT-800 composite material from Example 1 was added to each solution, stirred, and timing was started upon addition; the dosage of the FeCoNiMn / NCNT-800 composite material was 1 g / L. Similar to Application Experiment 1, the concentration C of each organic pollutant was measured at regular intervals. Results were obtained as follows... Figure 10 The graphs show the removal efficiency curves for different organic pollutants.
[0129] pass Figure 10 It can be seen that the removal rates of NOR, RhB, MO, MB, and TCH within 40 minutes were 98.7%, 97.8%, 100%, 100%, and 100%, respectively. The composite material of this disclosure exhibits excellent versatility, demonstrating high efficiency in removing various typical pollutants and excellent degradation performance. This strongly proves that the composite material of this disclosure is suitable for wastewater environments containing multiple organic pollutants, and can adapt to the complex components in various industrial wastewaters in practical applications, providing an efficient solution for wastewater treatment and demonstrating great potential in practical applications.
[0130] Application Experiment 4: Cyclic Stability Test of the Composite Material. Norfloxacin (NOR) solution with an initial concentration C0 of 20 mg / L and a pH of 7 was used as the degradation solution. The FeCoNiMn / NCNT-800 composite material from Example 1 was added to the degradation solution, stirred, and timing was started upon addition. Similar to Application Experiment 1, the concentration C of organic pollutants was measured at intervals to obtain the NOR removal efficiency curve of the composite material during the first use. The FeCoNiMn / NCNT-800 composite material was recovered using a magnet, washed three times with deionized water, and then vacuum-dried at 60°C for 10 h for the next cycle. This cycle was repeated to obtain the NOR removal rate of the FeCoNiMn / NCNT-800 composite material after 7 cycles. The results showed that the composite material has excellent stability. In the seven-cycle experiment, the NOR removal rates were 98.7%, 97.4%, 96.2%, 94.9%, 93.7%, 92.5%, and 91.2%, respectively. After seven cycles, the removal rate remained above 90%. This result supports the sustainability of composite materials in practical applications. It is evident that the cocktail effect and lattice distortion effect of high-entropy alloys endow them with higher stability than traditional single-metal catalysts. The catalysts maintain high activity even after several cycles, effectively avoiding resource waste.
[0131] This application is not limited to the structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.
[0132] In this application, each embodiment may focus on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other.
Claims
1. A high-entropy alloy composite material encapsulated with nitrogen-doped carbon nanotubes, characterized in that, The high-entropy alloy particles are dispersed in nitrogen-doped carbon nanotubes, and the high-entropy alloy includes magnetic metallic elements.
2. The high-entropy alloy composite material encapsulated with nitrogen-doped carbon nanotubes according to claim 1, characterized in that, High-entropy alloys include magnetic metallic elements selected from one or more of Fe, Co, Ni, and Cr; and / or High-entropy alloys also include one or more of Cu, Mn, and Zn; and / or High-entropy alloy particles include high-entropy alloy nanoparticles; and / or The particle size of the high-entropy alloy particles is less than or equal to 50 nm.
3. The high-entropy alloy composite material encapsulated with nitrogen-doped carbon nanotubes according to claim 1, characterized in that, High-entropy alloy composites include C=C bonds, C=C bonds, CN bonds, and C... O bond, C=O bond and O C=O bond; where M represents the metal in the high-entropy alloy.
4. The method for preparing the nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite material according to any one of claims 1 to 3, characterized in that, include: Prepare the corresponding metal salts based on the metal elements in the high-entropy alloy, add the metal salts to the solvent in an amount equal to the molar ratio of metal atoms, stir to dissolve, and obtain solution A; Melamine was added to solution A and mixed well to obtain dispersion B; After drying dispersion B, it was ground to obtain a powder mixture; The powder mixture was kept at a temperature of 700–1000 °C for a first preset time in an inert gas atmosphere, and then cooled to room temperature to obtain a high-entropy alloy composite material encapsulated with nitrogen-doped carbon nanotubes.
5. The preparation method according to claim 4, characterized in that, Metal salts are added to a solvent in an equal molar ratio of metal atoms, wherein the ratio of the amount of metal atoms of one metal salt to the amount of solvent is 1–2 mmol: 10–20 mL; and / or Melamine was added to solution A, and the molar ratio of the added melamine to the metal element of a metal salt was 8 to 15:
1.
6. The method for preparing the nitrogen-doped carbon-modified high-entropy alloy catalyst according to claim 4, characterized in that, The powder mixture is kept at a temperature of 800–1000°C for a first preset time in an inert gas atmosphere; or The powder mixture is kept at a temperature of 700–900°C in an inert gas atmosphere for a first preset time; or The powder mixture is kept at a temperature of 750–850°C for a first preset time in an inert gas atmosphere.
7. The method for preparing a nitrogen-doped carbon-modified high-entropy alloy catalyst according to claim 4, characterized in that, Drying dispersion B includes drying dispersion B at a drying temperature of 50–80°C.
8. The method for preparing the nitrogen-doped carbon-modified high-entropy alloy catalyst according to claim 4, characterized in that, The powder mixture is kept at a temperature of 700–1000°C in an inert gas atmosphere for a first preset time, including: The powder mixture is placed in an inert gas atmosphere and heated to 700-1000°C at a rate of 3-8°C / min and held at that temperature for a first preset time.
9. The composite material prepared by the method of preparing the nitrogen-doped carbon nanotube-encapsulated high-entropy alloy composite material as described in any one of claims 1 to 3 or as described in any one of claims 4 to 8, may be used as a microwave absorbing material in microwave absorbing coatings or as a catalyst in the degradation of organic pollutants in water.
10. The application according to claim 9, characterized in that, In the microwave absorbing coating, the mass percentage of the high-entropy alloy composite material wrapped with nitrogen-doped carbon nanotubes is 40% to 70%.