Three-dimensional nano iron-carbon foam alloy material as well as preparation method and application thereof

Abstract

The invention provides a three-dimensional nano iron-carbon foam alloy material as well as a preparation method and application thereof. According to the three-dimensional nano iron-carbon foam alloy material, iron and carbon elements form a continuous three-dimensional nano porous network structure; in the three-dimensional nano porous network structure, the carbon element serves as a structure stabilizer and forms an integrated alloy system with the iron element. The technical problem to be solved is how to obtain a three-dimensionally communicated nano-porous iron-carbon alloy system with stable structure and uniform pore diameter, solves the technical problems that an iron-based nano-porous material is easy to coarsen, the structure is easy to collapse and an iron component is easy to agglomerate and fall off, and provides a preparation scheme which is controllable in process, low in cost and suitable for large-scale production. And the specific surface area, the number of surface active sites, the mass transfer efficiency, the conductivity and the cycle service life of the material are synchronously improved, so that the high-performance application requirements in high-tech fields such as catalysis and electrochemical energy storage are met, and the material is more practical.

Description

Technical Field

[0001] This invention relates to the field of new materials technology, and in particular to a three-dimensional nano-iron-carbon foam alloy material, its preparation method, and its application. Background Technology

[0002] Nanoporous metallic materials, with their unique three-dimensional interconnected channels, high specific surface area, and abundant surface active sites, have broad application prospects in many high-tech fields such as catalysis, electrochemical energy storage, sensors, and biomedicine. Currently, research on nanoporous metallic materials is mostly focused on precious metal systems such as gold, silver, and platinum. Although mature preparation techniques have been developed through dealloying methods, the high cost of precious metals severely restricts their large-scale industrial application.

[0003] Iron-carbon alloys are inexpensive and widely used. If they can be fabricated into nanoporous structures, they can achieve a leap from structural materials to functional materials, which has great practical value. However, the current technology for preparing iron-based nanoporous materials faces obvious technical bottlenecks: First, precursor design is difficult. After dealloying, the nanoporous iron obtained from simple iron-based binary alloys has extremely poor structural stability and is prone to coarsening under thermal or stress conditions. Second, structural control is difficult. The dealloying parameters are sensitive and can easily lead to the collapse of the nanostructure or the formation of discontinuous pores. Third, performance is limited. In iron / carbon composite materials prepared by physical mixing, iron nanoparticles are prone to agglomeration and detachment, resulting in decreased material activity and shortened cycle life.

[0004] Existing technologies cannot overcome these problems: macroscopic iron-based or carbon-based foam materials prepared by powder metallurgy, template method or foaming method have pore sizes in the millimeter / micrometer range and do not have nanoscale effects, which limits their application fields and core performance; although nano-zero-valent iron particles and iron oxide particles can achieve nanoscale characteristics, their morphology is mostly isolated or aggregated particles, lacking a three-dimensional continuous and interconnected nano-network structure, which leads to inherent limitations in mass transfer efficiency, structural stability and conductivity, and cannot meet the high performance requirements of catalysis, energy storage and other fields. Summary of the Invention

[0005] The main objective of this invention is to provide a three-dimensional nano-iron-carbon foam alloy material, its preparation method, and its applications. The technical problem to be solved is how to obtain a nanoporous iron-carbon alloy system with stable structure, uniform pore size, and three-dimensional connectivity. This addresses the technical issues of easy coarsening, structural collapse, and agglomeration and detachment of iron-based nanoporous materials. Simultaneously, it provides a preparation scheme with controllable process, low cost, and suitability for large-scale production, while simultaneously improving the specific surface area, number of surface active sites, mass transfer efficiency, conductivity, and cycle life of the material. This makes it suitable for high-performance applications in high-tech fields such as catalysis and electrochemical energy storage, thus making it more practical.

[0006] The objective of this invention and the technical problem it solves are achieved by the following technical solution. According to this invention, a three-dimensional nano-iron-carbon foam alloy material is constructed from iron and carbon elements to form a continuous three-dimensional nanoporous network structure; in the three-dimensional nanoporous network structure, carbon elements act as a structural stabilizer, forming an integrated alloy system with iron elements.

[0007] The objectives of this invention and the technical problems it addresses can be further achieved by the following technical measures.

[0008] Preferably, in the aforementioned three-dimensional nano-iron-carbon foam alloy material, the ligament size of the network structure is 10-100 nanometers, the pore size is 20-200 nanometers, and the BET specific surface area of ​​the material is 30-150 m² / g.

[0009] The objective of this invention and the technical problem it solves are achieved through the following technical solution. A method for preparing a three-dimensional nano-iron-carbon foam alloy material according to this invention includes the following steps: S1 weighs raw materials according to the ratio of 20~40%Fe, 55~75%M and 1~10%C, where M is manganese or aluminum; it is smelted and cooled under an inert atmosphere to obtain a ternary precursor alloy ingot. S2 involves rapidly quenching a ternary precursor alloy ingot to obtain amorphous or microcrystalline thin strips or sheets; the thin strips or sheets are then immersed in an etching solution and reacted at 20-80℃ for 8-96 hours to remove M, yielding a nanoporous structured billet; when M is manganese, the etching solution is a 0.05-3.0 mol / L aqueous solution of sulfuric acid or hydrochloric acid; when M is aluminum, the etching solution is a 1-5 mol / L aqueous solution of sodium hydroxide. Wash with S3 until neutral and dry; heat to 250-550℃ at a heating rate of 1~10℃ / min under inert atmosphere protection, hold for 0.5-2 hours, and then cool with the furnace to obtain three-dimensional nano iron-carbon foam alloy material.

[0010] The objectives of this invention and the technical problems it addresses can be further achieved by the following technical measures.

[0011] Preferably, in the aforementioned preparation method, when M is manganese, the etching solution is a 0.1-2.0 mol / L sulfuric acid aqueous solution, and the reaction time is 24-72 hours at 50°C; and / or, when M is aluminum, the etching solution is a 2 mol / L sodium hydroxide aqueous solution, and the reaction time is 36 hours at 60°C.

[0012] Preferably, in the aforementioned preparation method, when M is manganese, the corrosive solution is a 2.0 mol / L sulfuric acid aqueous solution, and the reaction time is 24 hours.

[0013] Preferably, in the aforementioned preparation method, step S3 heat treatment involves heating to 400~450℃ at a heating rate of 5℃ / min and holding at that temperature for 1 hour.

[0014] Preferably, in the aforementioned preparation method, the inert atmosphere is argon; and the melting is carried out repeatedly in a vacuum arc melting furnace for 3 to 5 times.

[0015] Preferably, in the aforementioned preparation method, the rapid quenching is performed using a single-roller rapid quenching device, where the ternary precursor alloy ingot is remelted under argon protection and sprayed onto a copper roller rotating at 30 m / s to obtain a continuous thin strip with a thickness of 30 μm.

[0016] Preferably, in the aforementioned preparation method, the washing involves repeatedly washing the dealloyed product with deionized water and anhydrous ethanol until neutral; the drying is performed under vacuum at 60-80°C.

[0017] The objective of this invention and the technical problem it solves are achieved by the following technical solution. The invention provides the application of a three-dimensional nano-iron-carbon foam alloy material prepared according to the aforementioned method, or a three-dimensional nano-iron-carbon foam alloy material prepared according to the aforementioned method, in the fields of energy, environment, chemical engineering, or defense technology.

[0018] By employing the above technical solution, the three-dimensional nano-iron-carbon foam alloy material, its preparation method, and its application proposed in this invention have at least the following advantages: The three-dimensional nano-iron-carbon foam alloy material proposed in this invention relies on a continuous three-dimensional nanoporous network formed by iron and carbon, with carbon acting as a structural stabilizer to form an integrated alloy system. This solves the defect of traditional simple iron-based binary alloy porous materials being prone to coarsening under heat or stress. The integrated alloy system formed by carbon and iron can inhibit the migration and aggregation of iron ligaments, significantly improving the long-term stability of the material structure. The continuous three-dimensional nanoporous network structure provides abundant surface active sites while ensuring pore connectivity, greatly improving mass transfer efficiency and conductivity. It avoids the problem of activity decay caused by the easy aggregation and shedding of iron nanoparticles in physically mixed Fe / C composite materials, providing a structural basis for high-performance applications. It realizes the leap from low-cost iron-carbon alloys to functional materials, breaking the limitation of nanoporous metals relying on precious metals, and taking into account both performance and cost advantages.

[0019] Furthermore, the method for preparing three-dimensional nano-iron-carbon foam alloy materials proposed in this invention adopts a ternary precursor design, breaking through the limitations of simple iron-based binary alloy precursors and providing a compositional basis for stable nanoporous structures. Rapid quenching and cooling processes can obtain amorphous / microcrystalline structures, creating conditions for subsequent uniform dealloying and avoiding corrosion disorder caused by grain boundary inhomogeneity in traditional molten precursors. Differential corrosion schemes can precisely and selectively remove active metal M, preventing corrosion of the iron-carbon matrix and solving the problem of structural collapse or pore discontinuity easily caused by sensitive dealloying parameters. Low-temperature heat treatment further optimizes structural stability and avoids loss of nano-features due to high temperatures. The entire process parameters are clear and controllable, with strong repeatability and no need for complex equipment. Inert atmosphere melting ensures the uniformity of precursor composition and reduces the influence of impurities. The use of inexpensive Fe, Mn / Al, and C raw materials to replace precious metal systems significantly reduces costs, while each step is adapted for continuous operation, facilitating large-scale production and promotion.

[0020] Furthermore, the application of the three-dimensional nano-iron-carbon foam alloy material proposed in this invention, with its continuous three-dimensional nanoporous structure, high specific surface area, structural stability, and excellent mass transfer / conductivity, overcomes the performance limitations of macroscopic iron-based / carbon-based foams prepared by powder metallurgy / templating methods in catalysis, energy storage, and other fields due to their millimeter / micrometer-scale pore size and lack of nanoscale effects. It also solves the mass transfer and stability defects caused by the isolated / aggregated morphology of nano-zero-valent iron / iron oxide particles and the lack of a continuous network. It can be widely adapted to high-tech fields such as catalysis, electrochemical energy storage, and sensors, meeting the high-performance requirements of different scenarios for material activity, cycle life, and mass transfer efficiency, and providing low-cost, high-performance functional material solutions for related fields.

[0021] It overcomes the defect of easy coarsening of the porous structure of pure iron-based binary alloy under heat / stress, and avoids the problem of easy agglomeration and shedding of iron nanoparticles in physically mixed Fe / C composite materials, thus achieving long-term stability of the material structure; The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Detailed Implementation

[0022] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following detailed description, in conjunction with preferred embodiments, provides a three-dimensional nano-iron-carbon foam alloy material, its preparation method, and its application, including its specific implementation methods, structure, features, and effects. In the following description, different "embodiments" or "embodiments" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable manner.

[0023] This invention proposes a three-dimensional nano-iron-carbon foam alloy material, which is composed of a continuous three-dimensional nanoporous network structure of iron and carbon elements; in the three-dimensional nanoporous network structure, carbon elements act as structural stabilizers to form an integrated alloy system with iron elements.

[0024] In the above technical solution, carbon, which plays a role in structural stability, is introduced into the porous network structure. Due to its small atomic radius, carbon atoms can be embedded in the interstitial spaces of iron to form a solid solution, or segregate at the grain boundaries of the iron ligaments. Grain boundaries are the main channels for the migration of iron atoms. The segregation of carbon can reduce the grain boundary energy and hinder the long-range diffusion of iron atoms, thereby inhibiting the coarsening process of small ligament dissolution and large ligament growth. The ultrafine carbides formed by carbon and iron can be distributed in the iron ligaments as a dispersed strengthening phase, improving the mechanical strength of the ligaments and avoiding the problems of easy breakage and collapse caused by the thin ligaments of traditional nanoporous iron. For example, compared with Example 1, Comparative Example 8 is only different in that 5% of the carbon is replaced with iron. There is no carbon in Comparative Example 8. Although it can form nanoporous pure iron after dealloying, its ligaments are severely coarsened after heat treatment at 400℃. The BET specific surface area is reduced from 95m² / g in Example 1 to 15m² / g, and the ligament structure is obviously coarsened.

[0025] This invention also proposes a method for preparing a three-dimensional nano-iron-carbon foam alloy material, which includes the following steps: First, the raw materials are weighed according to the atomic percentage ratio of 20-40% Fe, 55-75% M and 1-10% C, where M is manganese or aluminum. In this step, the raw materials are high-purity elemental substances or high-purity carbon sources, with iron purity ≥99.9%, manganese / aluminum purity ≥99.5%, and high-purity graphite powder (purity ≥99.9%, particle size 5-10μm) used as the carbon source. Weighing is performed using an electronic balance with an accuracy of 0.1mg, strictly following the atomic percentage conversion of 20-40% Fe, 55-75% M (M=Mn / Al), and 1-10% C. The purpose of this setup is to prevent impurities (such as oxygen, sulfur, and silicon) from low-purity raw materials from being introduced into the alloy system, preventing the formation of harmful compounds such as Fe3O4 and MnS, or causing localized component segregation that affects the uniformity of the subsequent nanoporous structure. The precursor alloy has an elemental purity ≥99.5% and no obvious impurity phases, ensuring the quality of the uniform ternary alloy ingot formed during subsequent melting and avoiding dealloying dead zones caused by impurities, which could lead to localized insolubility of the M element.

[0026] Melting and cooling are carried out under an inert atmosphere to obtain a ternary precursor alloy ingot. In this step, a vacuum arc melting furnace is used for melting. Specifically, the vacuum degree in the furnace is first evacuated to ≤5×10⁻³Pa, and then high-purity argon gas (purity ≥99.99%) is introduced to atmospheric pressure. Then, the arc is started to completely melt the raw materials. After each melting, the alloy ingot is rotated 180° and the melting is repeated 3-5 times. After melting, it is naturally cooled to room temperature to obtain a ternary precursor alloy ingot with a diameter of 20-30mm and a thickness of 5-8mm. The technical purpose of this setup is to prevent the oxidation of Fe and M elements during the smelting process through vacuum degassing and argon protection; to promote the full diffusion of Fe, M, and C atoms through repeated smelting and breaking the boundaries of raw material particles, thus eliminating the problems of excessively high local carbon content leading to the formation of coarse graphite phases, or excessively low iron content leading to the inability to form a continuous network in the later stages; through the above operations, a precursor alloy ingot with uniform composition can be obtained. EDS (energy dispersive spectroscopy) analysis shows that the distribution deviation of Fe, M, and C elements is ≤10%, with no obvious component enrichment areas, avoiding the defect of coarse carbides destroying the uniformity of the alloy.

[0027] The ternary precursor alloy ingot is rapidly quenched to obtain amorphous or microcrystalline ribbons or sheets. In this step, a single-roller rapid quenching device is used. The precursor alloy ingot is first cut into small pieces of 5-10g and placed in a quartz crucible. After purging the air by introducing argon gas into the furnace, the ingot is remelted by high-frequency induction heating to 100-200°C above the alloy melting point. After the alloy is completely melted, the molten liquid is sprayed onto the surface of a high-speed rotating copper roller through a quartz nozzle. The rotation speed of the copper roller is 20-40m / s, preferably 30m / s, and the final product is a continuous amorphous / microcrystalline ribbon with a thickness of 20-40μm, preferably 30μm, and a width of 5-10mm. The technical purpose of this setup is to suppress crystal growth through rapid cooling, avoiding the coarse grains formed by traditional slow cooling processes that lead to uneven subsequent corrosion; the amorphous / microcrystalline structure has no obvious grain boundary segregation, which can ensure that the M element is uniformly distributed in the alloy, thus facilitating subsequent selective dissolution; SEM (scanning electron microscopy) observation shows no pores or inclusions, thereby ensuring that subsequent dealloying forms uniform pore size.

[0028] Thin strips or sheets are immersed in an etching solution and reacted at 20-80℃ for 8-96 hours to remove nitrogen (M), obtaining a nanoporous preform. The rapidly quenched strip is then cut into small pieces of 0.5-1g each, with an area of ​​approximately 1-2cm², and placed in a PTFE-lined reactor. 100-200mL of etching solution is added, maintaining a liquid-to-solid ratio of 200:1 to ensure complete immersion of the strip. The reactor is placed in a constant-temperature water bath, with magnetic stirring at 200-300 rpm, and the reaction time controlled at 20-80℃ for 8-96 hours. The technical purpose of this setup is to improve the contact efficiency between the etching solution and the strip through the combination of cutting into small pieces, stirring, and a constant-temperature water bath. This avoids residual M due to localized areas not being in contact with the etching solution caused by strip stacking. The constant-temperature water bath stabilizes the etching reaction rate and prevents uneven M dissolution caused by temperature fluctuations. Excessive temperature may accelerate iron dissolution, while insufficient temperature may result in incomplete M dissolution. Generally, it is preferred to control the removal rate of M element to ≥98%, and the residual M content should be <0.2wt% as detected by ICP-MS. The porous preform formed after corrosion should have no uncorroded areas and good pore connectivity.

[0029] When M is manganese, the corrosive solution is a 0.05-3.0 mol / L aqueous solution of sulfuric acid or hydrochloric acid. This is because the standard electrode potential of manganese is much lower than that of iron. In acid of this concentration, manganese can undergo a rapid displacement reaction: Mn + H₂SO₄ = MnSO₄ + H₂↑, producing soluble MnSO₄, while the dissolution rate of iron is extremely slow, with an iron loss rate of <0.5% per hour. If oxidizing acids such as nitric acid are used, iron may be oxidized to form Fe³⁺. + This invention selectively dissolves manganese in a corrosion solution adapted to M metal, removing only the active metal M from the precursor while preserving the iron-carbon framework to form a porous structure, thus preventing structural collapse due to corrosion of the iron base. Further optimization of process parameters ensures stable and superior performance. The invention further preferably uses a 0.1-2.0 mol / L sulfuric acid aqueous solution as the corrosion solution, reacting at 50°C for 24-72 hours; even more preferably, a 2.0 mol / L sulfuric acid aqueous solution is used, with a reaction time of 24 hours.

[0030] When M is aluminum, the etching solution is a 1-5 mol / L sodium hydroxide aqueous solution. This is because aluminum is an amphoteric metal and can react with NaOH: 2Al + 2NaOH + 2H₂O = 2NaAlO₂ + 3H₂↑, generating soluble NaAlO₂. Iron, on the other hand, has high chemical stability under alkaline conditions and does not react with NaOH, only forming a very thin passivation film on its surface. If an acid solution is used, both aluminum and iron will dissolve simultaneously, preventing the formation of a porous structure. This invention uses an etching solution adapted to metal M to specifically remove aluminum while protecting the iron-carbon matrix from corrosion, ensuring the integrity of the porous structure and avoiding structural disorder defects caused by acid corrosion of the aluminum system. Further optimization of process parameters ensures stable and superior performance. This invention further optimizes the etching solution to a 2 mol / L sodium hydroxide aqueous solution, reacting at 60°C for 36 hours.

[0031] The obtained nanoporous preform is washed until neutral. Specifically, the preform is transferred to a centrifuge tube, 50 mL of deionized water is added, and the tube is centrifuged at 3000-5000 rpm for 5-10 minutes. The supernatant is discarded. This deionized water washing step is repeated 3-4 times until the pH of the supernatant reaches 6.5-7.5 (tested with precision pH paper). Then, 50 mL of anhydrous ethanol is added, and the tube is centrifuged and washed twice under the same conditions to remove residual water and organic impurities. The purpose of this technique is to thoroughly remove residual corrosive liquid ions (such as SO4²⁻, Cl⁻, Na⁺) from the surface and pores of the porous preform, preventing these ions from reacting with iron to form impurities such as FeSO4 and FeCl2 during subsequent heat treatment, or from poisoning active sites in applications (such as catalysis). Washing with anhydrous ethanol can accelerate water evaporation and shorten drying time. X-ray fluorescence spectroscopy analysis showed that the residual ion content of the washed product was <0.1wt%, the pH value remained stable in the neutral range, and there was no risk of secondary corrosion caused by residual corrosive liquid, thus ensuring structural stability during subsequent heat treatment.

[0032] Next, it undergoes a drying process. Specifically, the washed porous preform is placed in a vacuum drying oven, the oven door is closed, and a vacuum is drawn to ≤-0.09 MPa. The drying temperature is set at 60-80℃, preferably 70℃, and the drying time is 6-8 hours. During the drying process, it is observed every 2 hours to avoid structural damage caused by abnormal pressure inside the drying oven. Thermogravimetric analysis shows that the water content of the dried product is <0.5wt%, XRD pattern indicates no oxidation peaks or oxidation phenomena, the porous structure remains intact, and the ligament size shows no significant change.

[0033] Under an inert atmosphere, the temperature is increased to 250-550℃ at a rate of 1-10℃ / min. Specifically, the dried product is placed in a quartz boat and then placed in a tube furnace. High-purity argon gas (purity ≥99.99%) is first introduced into the tube furnace at a flow rate of 50-100 mL / min for 30 minutes to purge the air from the furnace. Then, the heating program is started, and the temperature is increased from room temperature to 250-550℃ at a rate of 1-10℃ / min, preferably 5℃ / min. The furnace temperature is monitored in real time during the heating process to ensure a stable rate, with fluctuations of ±0.5℃ / min. Argon protection isolates oxygen and prevents oxidation of the iron-carbon structure during heat treatment. Slow heating avoids thermal stress caused by sudden temperature increases, which could lead to pore cracking or ligament rupture. The temperature range of 250-550℃ promotes the crystallization of the iron-carbon system while avoiding Oswald ripening (ligament coarsening and pore merging) caused by high temperatures (>600℃). SEM and EDS characterization showed that the product after heat treatment was a porous iron-carbon alloy, and the defects of nanostructure loss and transformation into micron-sized porous structure were well avoided. Further optimization was achieved by heating to 400-450℃.

[0034] After heating to the target temperature, maintain a stable temperature (fluctuation ±2℃) for 0.5-2 hours, preferably 1 hour. During the holding period, argon gas is continuously introduced to ensure an inert environment within the furnace. After the holding period, the heating program is turned off, and argon gas is continued to be introduced until the tubular furnace cools naturally to room temperature, which takes approximately 4-6 hours. The holding period allows sufficient time for iron and carbon atoms to diffuse and rearrange, eliminating internal stress generated during dealloying. Simultaneously, it allows carbon atoms to be further evenly dispersed within the iron ligaments, strengthening the role of carbon as a structural stabilizer. Continuous argon gas protection prevents air from entering the furnace during cooling and causing oxidation. The structural stability of the material is significantly improved after heat treatment. After being placed at 300℃ for 100 hours, the ligament coarsening rate is <10%, and the BET specific surface area decay rate is <5%, avoiding problems such as poor crystallinity and weak structural stability.

[0035] After the furnace cooled to room temperature, the argon gas was turned off, the tube furnace was opened, and the quartz boat was removed. The product was then transferred to a desiccator for storage to prevent the adsorption of moisture from the air, ultimately yielding a black, fluffy three-dimensional nano-iron-carbon foam alloy material. The product underwent structural characterization (SEM, BET) and performance testing (such as catalytic activity and conductivity) to ensure it met the requirements of ligament size 10-100 nm, pore size 20-200 nm, and BET specific surface area 30-150 m² / g. The slow furnace cooling rate (5-10℃ / min) avoided thermal stress from rapid cooling that could damage the porous network; desiccator storage prevented the product from adsorbing moisture from the air, thus avoiding slight oxidation of the iron-based structure. The final product exhibited good interconnectivity in its three-dimensional nanoporous structure. SEM observation showed that the pore size and ligament size deviations were ≤15%, and the BET specific surface area met the design range. It can be directly used in catalysis, electrochemical energy storage, and other fields, meeting the requirements for high-performance applications.

[0036] The present invention also proposes the application of the aforementioned three-dimensional nano-iron-carbon foam alloy material, or the three-dimensional nano-iron-carbon foam alloy material prepared according to the aforementioned preparation method, in the fields of energy, environment, chemical industry, or defense technology.

[0037] The present invention will be further described below with reference to specific embodiments, but this should not be construed as a limitation on the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention still fall within the scope of protection of the present invention.

[0038] Unless otherwise specified, all materials and reagents mentioned below are commercially available products well known to those skilled in the art; unless otherwise specified, all methods described are methods known in the art. Unless otherwise defined, the technical or scientific terms used should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0039] Example 1 This embodiment prepares a three-dimensional nano-iron-carbon foam alloy material. Based on a total atomic count of 100 parts, the atomic ratio in the ternary precursor of this embodiment is Fe... 25 Mn 70 C5. The specific steps include: 1) According to atomic ratio Fe 25 Mn 70 C5 high-purity raw materials were weighed and repeatedly melted four times in a vacuum arc melting furnace under argon protection to obtain Fe with uniform composition. 25 Mn 70 C5 precursor alloy ingot.

[0040] 2) Using a single-roll rapid cooling and quenching equipment, the alloy ingot is remelted under argon protection and sprayed onto a copper roller with a rotation speed of 30 m / s to prepare a continuous thin strip with a thickness of about 30 μm.

[0041] 3) Take 0.5 g of the above-mentioned thin strip and immerse it in 100 mL of 1.0 mol / L H2SO4 solution, and etch it in a constant temperature water bath at 50℃ for 24 hours.

[0042] 4) After the reaction is complete, wash the product with deionized water and anhydrous ethanol by centrifugation until neutral, and then dry it in a vacuum drying oven at 80°C for 6 hours.

[0043] 5) Place the dried sample in a tube furnace and heat it to 400°C at 5°C / min under argon protection. Hold the temperature for 1 hour and then cool it with the furnace to obtain the final product.

[0044] Testing revealed that the product prepared in this embodiment possesses a three-dimensional nanoporous structure with a pore size of 50-100 nm, a ligament diameter of 30-50 nm, and a BET specific surface area of ​​95 m². 2 / g.

[0045] Example 2 Same as Example 1, except that the atomic ratio of the precursor is Fe. 40 Mn 55 C5.

[0046] Testing revealed that the product prepared in this embodiment has a smaller pore size (20-50 nm), thicker ligaments, and a BET specific surface area of ​​65 m². 2 / g.

[0047] Example 3 Same as Example 1, except that: the etching solution used is 0.1 mol / L H2SO4, and the etching time is 72h.

[0048] Testing revealed that the product prepared in this embodiment has a more uniform structure, smoother ligaments, and a BET specific surface area of ​​105 m². 2 / g.

[0049] Example 4 This embodiment prepares a three-dimensional nano-iron-carbon foam alloy material. Based on a total atomic count of 100 parts, the atomic ratio in the ternary precursor of this embodiment is Fe... 30 Al 65 C5. The specific steps include: 1) Weigh high-purity iron, aluminum, and carbon source according to the specified ratio, and repeatedly melt them four times in a vacuum arc melting furnace under argon protection to obtain Fe with uniform composition. 30 Al 65 C5 precursor alloy ingot.

[0050] 2) Using a single-roll rapid cooling and quenching equipment, the alloy ingot is remelted under argon protection and sprayed onto a high-speed rotating copper roller to prepare a continuous thin strip with a thickness of about 30 μm.

[0051] 3) Take 0.5 g of the above-mentioned strip and immerse it in 100 mL of 2.0 mol / L NaOH solution, then etch it in a constant temperature water bath at 60℃ for 36 hours. The alkaline environment selectively dissolves aluminum.

[0052] 4) After the reaction is complete, the product is washed with deionized water and anhydrous ethanol by centrifugation until neutral, and then dried in a vacuum drying oven at 80°C for 6 hours.

[0053] 5) Place the dried sample in a tube furnace and heat it to 450°C at 5°C / min under argon protection. Hold the temperature for 1 hour and then cool it with the furnace to obtain the final product.

[0054] Testing revealed that the product prepared in this embodiment possesses a three-dimensional nanoporous structure with a pore size of 40-100 nm, a ligament diameter of 20-50 nm, and a BET specific surface area of ​​85 m². 2 / g.

[0055] Example 5 Same as Example 4, except that the atomic ratio of the precursor is Fe. 40 Al 55 C5.

[0056] Testing revealed that the product prepared in this embodiment has a smaller pore size (20-60 nm), thicker ligaments, and a BET specific surface area of ​​60 m². 2 / g.

[0057] Example 6 Same as Example 1, except that the atomic ratio of the precursor is Fe. 27 Mn 70 C3.

[0058] Testing showed that the product prepared in this embodiment can form a nanoporous structure with a pore size of 60-110 nm and a BET specific surface area of ​​75 m². 2 / g.

[0059] Example 7 Same as Example 1, except that the atomic ratio of the precursor is Fe. 20 Mn 70 C 10 .

[0060] Testing showed that the product prepared in this embodiment can form a nanoporous structure with a pore size of 30-70 nm and a BET specific surface area of ​​80 m². 2 / g.

[0061] Example 8 Similar to Example 1, the difference is that the etching solution used is 0.05 mol / L H2SO4, and the etching time is 96 hours. The etching rate in this example is extremely slow; however, testing shows that the product prepared in this example still forms a nanoporous structure with uniform structure, pore size of 30-80 nm, and a BET specific surface area of ​​108 m². 2 / g.

[0062] Example 9 Similar to Example 1, the difference is that the etching solution used is 3 mol / L H2SO4, and the etching time is 8 hours. In this example, the etching solution concentration is at the upper limit of the effective boundary, resulting in a rapid etching rate and the formation of a nanoporous structure.

[0063] Testing revealed that the ligaments prepared in this embodiment were slightly rough, with a pore size of 80-150 nm and a BET specific surface area of ​​70 m². 2 / g.

[0064] Example 10 Same as Example 1, except that the heat treatment temperature after dealloying is 250°C.

[0065] Testing revealed that the preparation process in this embodiment exhibited slightly insufficient stability, and the prepared product had a pore size of 48-98 nm and a BET specific surface area of ​​90 m². 2 / g.

[0066] Example 11 Same as Example 1, except that the heat treatment temperature after dealloying is 550°C.

[0067] Testing revealed that the product prepared in this embodiment maintained a nanoporous structure, but the ligaments showed slight coarsening, a slight decrease in specific surface area, a pore size of 60-130 nm, and a BET specific surface area of ​​75 m². 2 / g.

[0068] Comparative Example 1 Same as Example 1, except that the atomic ratio of the precursor is Fe. 80 Mn 15 C5.

[0069] Testing revealed that the product prepared in this comparative example could not form a continuous nanoporous structure, exhibiting only surface pits. The BET specific surface area was 8 m² / g.

[0070] Comparative Example 2 Same as Example 1, except that: the etching solution used is 5.0 mol / L H2SO4, and the etching time is 4 hours.

[0071] Testing revealed that in this embodiment, due to excessively high concentration of the corrosive solution and overly severe corrosion, the structure collapsed and excessively dissolved, the ligaments coarsened, and the specific surface area and performance significantly decreased, with pore size >200 nm and BET specific surface area 22 m². 2 / g.

[0072] Comparative Example 3 Same as Example 1, except that: heat treatment process is not included.

[0073] Testing revealed that the product prepared in this comparative example exhibited the initial structure after dealloying, with poor crystallinity, weak structural stability, a pore size of 45-95 nm, and a BET specific surface area of ​​98 m². 2 / g.

[0074] Comparative Example 4 Purchase commercially available micron-sized reduced iron powder with an average particle size of 5μm.

[0075] Tests showed that its BET specific surface area was <1 m² / g.

[0076] Comparative Example 5 In this comparative example, Fe / C nanocomposite particles were prepared by coprecipitation-thermal reduction method. The steps were as follows: FeCl3•6H2O and glucose were dissolved in water, the pH was adjusted to alkaline with NaOH, the hydrothermal reaction was followed by centrifugation and drying, and then annealing at 600℃ for 2 hours in argon.

[0077] Testing revealed that the product prepared in this comparative example was a nanoparticle aggregate without interconnected three-dimensional channels, and had a BET specific surface area of ​​45 m² / g.

[0078] Comparative Example 6 Same as Example 4, except that the etchant used is 1.0 mol / L H2SO4.

[0079] Testing revealed that iron and aluminum were co-corroded in the product prepared in this comparative example, preventing the formation of a nanoporous structure and resulting in a disordered mixture.

[0080] Comparative Example 7 Same as Example 4, except that the atomic ratio of the precursor is Fe. 70 Al 25 C5.

[0081] Testing revealed that the product prepared in this comparative example could not form a continuous nanoporous structure.

[0082] Comparative Example 8 Same as Example 1, except that the atomic ratio of the precursor is Fe. 30 Mn 70 C0 (carbon-free).

[0083] Testing revealed that although the product prepared in this comparative example could form a nanoporous pure iron structure after dealloying, severe ligament coarsening occurred during subsequent heat treatment (400℃), and the nanostructure was destroyed, resulting in a BET specific surface area of ​​15 m². 2 / g.

[0084] Comparative Example 9 Same as Example 1, except that the atomic ratio of the precursor is Fe. 15 Mn 70 C 15 .

[0085] Testing revealed that the carbon content of the product prepared in this comparative example was too high, and a large number of coarse carbides or graphite phases appeared in the precursor, which damaged the alloy uniformity; after dealloying, a uniform nano-network could not be formed, and the structure was disordered.

[0086] Comparative Example 10 Same as Example 1, except that: the etching solution used is 0.01 mol / L H2SO4, and the etching time is 240h.

[0087] Testing revealed that, due to the excessively low concentration of the corrosive solution, the corrosion reaction in this comparative example had almost ceased before completion, with only slight corrosion on the surface and most of the internal precursors remaining uncorroded, thus preventing the production of bulk nanofoam material.

[0088] Comparative Example 11 Same as Example 1, except that the heat treatment temperature after dealloying is 700°C.

[0089] Testing revealed that the comparative sample underwent severe Oswald curing of its nanostructure due to excessively high heat treatment temperature. This resulted in ligament rupture, pore merging, and the near loss of nanoporous characteristics, transforming it into a microporous structure.

[0090] As can be seen from the above examples and comparative test data, the atomic ratio of the precursor (Fe 20-40%, M 55-75%, C 1-10%) is the foundation for achieving a stable three-dimensional nanoporous structure. These three elements are complementary and mutually restrictive. Fe is the core element forming the alloy framework; it is necessary to ensure that the Fe remaining after dealloying can construct a continuous three-dimensional network, rather than isolated particles. At the same time, excessive Fe should be avoided to prevent insufficient sacrificial phase M, which would prevent the formation of sufficient pores. M, as the sacrificial phase, needs to be selectively removed through subsequent dealloying. Its ratio directly determines the number, connectivity, and pore size of the pores. A higher M ratio results in more removable metal and more sufficient pore space; conversely, a lower M ratio leads to insufficient or discontinuous pores. C, as a structural stabilizer, needs to be embedded... Fe lattices may segregate at grain boundaries, inhibiting the coarsening of Fe ligaments under heat / stress, while avoiding excessive C forming coarse carbides / graphite phases that would disrupt alloy homogeneity; insufficient C would prevent it from playing a stabilizing role; the individual elemental ratios of the above three atoms are still not within the required range, and all three need to be matched synergistically to obtain a product with a stable structure, high specific surface area, and interconnected channels. For example, Comparative Examples 1 and 7 could not form continuous channels due to insufficient M, Comparative Example 8 suffered severe ligament coarsening and nanostructure destruction due to the lack of carbon, and Comparative Example 9 could not form a uniform nanonetwork after dealloying due to its high carbon content, resulting in a disordered structure.

[0091] As can be seen from the above examples and comparative test data, heat treatment temperature is also a key process parameter for controlling the structural stability, pore size distribution, and specific surface area of ​​three-dimensional nano-iron-carbon foam alloy materials. Its influence on material properties exhibits a clear pattern. For example, Comparative Example 3 did not include a heat treatment process, although its product still had a BET specific surface area as high as 98 m². 2 / g, but due to its poor crystallinity and weak structural stability, it is difficult to adapt to actual application scenarios; the heat treatment temperature of Comparative Example 11 is as high as 700℃. Due to its excessively high heat treatment temperature, the nanostructure undergoes severe Oswald ripening, the ligament connection breaks, the pores merge, the nanoporous characteristics are basically lost, and it is transformed into a microporous structure. The test data from the examples also show that although the heat treatment process can form three-dimensional nano-iron-carbon foam alloy materials after holding at 250-550℃ for 0.5-2 hours, the overall performance of the products is generally poor due to the heat treatment process being close to the process boundary. The materials prepared at a heat treatment temperature of 400-450℃ have the best overall performance. For example, the product of Example 1 forms a three-dimensional interconnected porous structure with uniform pore size (50-100nm) and moderate ligament size (30-50nm), with a BET specific surface area of ​​95m² / g, and has high active sites, good mass transfer efficiency and structural stability. Example 4, after heat treatment at 450℃, also obtained a stable nanoporous structure with a pore size of 40-100nm and a BET of 85m² / g, verifying the universality of this temperature range.

[0092] As can be seen from the above examples and comparative test data, the corrosion process also has an important impact on the structural control of the three-dimensional nano-iron-carbon foam alloy material. Although a nanoporous structure blank can be obtained by reacting at a temperature of 20-80℃ for 8-96 hours to remove M (when M is manganese, the corrosion solution is a 0.05-3.0 mol / L sulfuric acid or hydrochloric acid aqueous solution; when M is aluminum, the corrosion solution is a 1-5 mol / L sodium hydroxide aqueous solution); however, when M is manganese, it is further preferred to use a 0.1-2.0 mol / L sulfuric acid aqueous solution and react at 50℃ for 24-72 hours; even more preferably, the corrosion solution is a 2.0 mol / L sulfuric acid aqueous solution and reacts for 24 hours; when M is aluminum, it is further preferred to use a 2 mol / L sodium hydroxide aqueous solution and react at 60℃ for 36 hours.

[0093] The technical features in the claims and / or specification of this invention can be combined, and the combination is not limited to the combinations obtained through reference in the claims. Technical solutions obtained by combining the technical features in the claims and / or specification are also within the scope of protection of this invention.

[0094] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A three-dimensional nano-iron-carbon foam alloy material, characterized in that, A continuous three-dimensional nanoporous network structure is formed by iron and carbon elements; in the three-dimensional nanoporous network structure, carbon elements act as structural stabilizers and form an integrated alloy system with iron elements.

2. The three-dimensional nano-iron-carbon foam alloy material according to claim 1, characterized in that, The ligament size of the network structure is 10-100 nanometers, and the pore size is 20-200 nanometers; the BET specific surface area of ​​the material is 30-150 m² / g.

3. A method for preparing a three-dimensional nano-iron-carbon foam alloy material, characterized in that, It includes the following steps: S1 weighs raw materials according to the ratio of 20~40%Fe, 55~75%M and 1~10%C, where M is manganese or aluminum; it is smelted and cooled under an inert atmosphere to obtain a ternary precursor alloy ingot. S2 involves rapidly quenching a ternary precursor alloy ingot to obtain amorphous or microcrystalline thin strips or sheets; the thin strips or sheets are then immersed in an etching solution and reacted at 20-80℃ for 8-96 hours to remove M, yielding a nanoporous structured billet; when M is manganese, the etching solution is a 0.05-3.0 mol / L aqueous solution of sulfuric acid or hydrochloric acid; when M is aluminum, the etching solution is a 1-5 mol / L aqueous solution of sodium hydroxide. Wash with S3 until neutral, then dry. Under an inert atmosphere, the temperature is increased to 250-550℃ at a heating rate of 1-10℃ / min, held for 0.5-2 hours, and then cooled with the furnace to obtain a three-dimensional nano-iron-carbon foam alloy material.

4. The preparation method according to claim 3, characterized in that, When M is manganese, the corrosion solution is a 0.1-2.0 mol / L sulfuric acid aqueous solution, and the reaction time is 24-72 hours at 50℃; and / or, when M is aluminum, the corrosion solution is a 2 mol / L sodium hydroxide aqueous solution, and the reaction time is 36 hours at 60℃.

5. The preparation method according to claim 4, characterized in that, When M is manganese, the corrosive solution is a 2.0 mol / L sulfuric acid aqueous solution, and the reaction time is 24 hours.

6. The preparation method according to claim 3, characterized in that, Step S3 heat treatment involves heating the temperature to 400~450℃ at a rate of 5℃ / min and holding it at that temperature for 1 hour.

7. The preparation method according to claim 3, characterized in that, The inert atmosphere is argon; the melting process is carried out repeatedly in a vacuum arc melting furnace for 3 to 5 times.

8. The preparation method according to claim 3, characterized in that, The rapid cooling and quenching process involves using a single-roller rapid cooling and quenching device to remelt the ternary precursor alloy ingot under argon protection and spray it onto a copper roller rotating at 30 m / s to obtain a continuous thin strip with a thickness of 30 μm.

9. The preparation method according to claim 3, characterized in that, The washing process involves repeatedly washing the dealloyed product with deionized water and anhydrous ethanol until it becomes neutral; the drying process involves vacuum drying at 60-80°C.

10. The application of a three-dimensional nano-iron-carbon foam alloy material according to claim 1 or 2, or a three-dimensional nano-iron-carbon foam alloy material prepared by the preparation method according to any one of claims 3 to 9, in the fields of energy, environment, chemical industry, or defense technology.