Preparation method of high-entropy alloy loaded carbon fiber aerogel electrocatalytic material

Abstract

The application belongs to the field of preparation process of aerogel materials, and particularly relates to a preparation method of high-entropy alloy loaded carbon fiber aerogel electrocatalytic material. Five kinds of metal salts, a polymer and ZIF-8 are uniformly mixed in a solvent to obtain nanofibers through electrospinning, the nitrogen-doped carbon skeleton derived from the polymer and ZIF-8 pyrolysis is used to significantly enhance the integrity and thermal stability of the fiber structure, and then the pre-oxidation and high-temperature reduction treatment are combined with the freeze-drying method to obtain the composite material in which high-entropy alloy nanoparticles are uniformly loaded on the nitrogen-doped carbon fiber aerogel. The application has the advantages of simple process, controllable structure and high metal utilization rate, and the obtained material has the advantages of large specific surface area, rich active sites and excellent electrochemical stability, is suitable for multifunctional electrocatalytic applications such as oxygen reduction reaction, and is easy to realize large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of aerogel material preparation technology, and relates to a method for preparing a low-cost, high-catalytic-activity aerogel electrocatalytic material using electrospinning technology combined with freeze-drying process. Background Technology

[0002] With the increasing demand for renewable energy, and in order to address the growing energy crisis, high-efficiency energy storage systems such as fuel cells and metal-air batteries have been developed. Among them, the zinc-air battery uses abundant zinc as the cathode and oxygen as the anode, achieving a theoretical energy density of up to 1086 Wh·kg⁻¹. -1 This provides a green, safe, and efficient alternative for next-generation energy storage devices. Currently, the research breakthrough for rechargeable ZABs lies in developing high-performance cathode electrocatalysts, particularly for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), whose slow kinetics severely limit the charging and discharging processes of ZABs. To date, extensive research has been conducted on noble metal-based electrocatalysts (Pd, Pt, Au, Ru, Ir, Rh, etc.), but their widespread application is limited by their scarcity and high cost. Therefore, developing a low-cost, highly active, and highly stable electrocatalyst is of great significance.

[0003] High entropy alloys (HEAs) are multi-element alloys composed of five or more metallic elements. They possess characteristics such as high entropy effect, cocktail effect, slow diffusion, lattice distortion, and flexible element combination, making them widely used in catalytic research for various chemical conversions and clean energy devices. For example, Luo et al. reported a sub-2 nm IrRuRhMoW HEAs with significant local microstrain, exhibiting a HOR kinetic current density 22.47 times higher than commercial Pt / C at 50 mV vs. RHE. By simultaneously adjusting the hydrogen adsorption binding energy and the enhanced ligand and microstrain effects of IrRuRhMoW HEAs, weakened hydrogen and enhanced hydroxyl adsorption were achieved, thus ensuring its superior performance for HOR / HER. Furthermore, Chandran M et al., using a simple room-temperature electrodeposition method combined with theoretically calculated PtPdNiCoMn HEAs, achieved continuous operation for 100 hours at high current densities, demonstrating excellent performance even under harsh electrolyte conditions simulating seawater. However, alloy nanoparticles often tend to spontaneously aggregate during catalysis, leading to the coverage of active sites. The combination of metals and carbon components brings excellent electrical properties and thermodynamic stability, significantly reducing the synthesis cost of catalysts while enhancing catalytic activity, which has attracted widespread attention from researchers in recent years. He synthesized HEAs nanoparticles with an average size of <2 nm using a one-step continuous-flow spray pyrolysis strategy, uniformly dispersed on substrates such as graphene and carbon black. He also identified a hydrocarbon thermal synthesis mechanism, where H2 is generated in situ through the reaction between carbon and water in aerosol droplets, thereby achieving complete reduction and alloying of the metal at a reduced temperature. However, current reported HEAs research mainly focuses on the construction of low-dimensional structures, which significantly limits the exposure of catalytic sites and the improvement of mass transfer efficiency. Therefore, developing HEAs with three-dimensional structures is of great significance for further increasing the density of active sites, optimizing reactant / product transport pathways, and ultimately improving overall catalytic performance.

[0004] Aerogels, as typical three-dimensional porous materials, offer abundant catalytic active sites and mass transfer channels due to their high specific surface area and high porosity, accelerating mass transfer in electrocatalysis. Carbon fiber aerogels synthesized from electrospun polymer fibers possess three-dimensional porosity and high specific surface area, which can facilitate the good dispersion of metal ion precursors, ultimately resulting in uniform distribution of alloy particles on the carbon fibers. However, the feasibility of this method is largely limited by the structural stability of the carbon fiber substrate during heat treatment. This structural instability may weaken the anchoring effect of the substrate on the metal nanoparticles, becoming a key bottleneck restricting the catalytic performance of such materials. Therefore, realizing high-entropy alloy electrocatalytic materials that combine low cost, high catalytic activity, and high stability remains a significant challenge. Summary of the Invention

[0005] This invention utilizes the confinement reinforcement properties of ZIF-8 combined with electrospinning technology to prepare a HEAs-supported carbon fiber aerogel electrocatalyst with low metal loading, high catalytic activity, and high stability. The aim is to provide a method for preparing HEAs-supported carbon fiber aerogel catalysts for fuel cells, addressing the shortcomings of existing electrocatalytic materials such as high cost, poor stability, and insufficient activity. This method features simple raw materials and processes, low energy consumption, and controllable structure. The prepared aerogel material possesses characteristics such as low density, high specific surface area, and high porosity, which is of positive significance for realizing the application of HEAs-supported carbon fiber aerogels in the field of electrocatalysis.

[0006] The objective of this invention is achieved through the following technical solution: a method for preparing a high-entropy alloy-supported carbon fiber aerogel catalytic material, the specific steps of which are as follows: (1) Dissolve a certain amount of zinc source in 200 mL of alcohol to form a homogeneous solution A; (2) Subsequently, a certain amount of 2-methylimidazole was dissolved in 200 mL of alcohol to form a homogeneous solution B; (3) Mix solutions A and B and stir under water bath conditions to obtain a uniform suspension. After centrifugation, collect the product and wash it with alcohol. (4) The washed product was placed in an oven and dried for 1-6 h to finally obtain ZIF-8 nanoparticles; (5) Add polyacrylonitrile to the spinning solvent and stir for 2-12 h to dissolve and form a uniform and transparent spinning solution; (6) Take five metal salts in equal amounts and dissolve them in the spinning solution, stir for 20-180 min to obtain a mixed solution; the metal salts are any four of platinum salt, copper salt, nickel salt, cobalt salt, manganese salt and iron salt mixed with palladium chloride; (7) Subsequently, the synthesized ZIF-8 powder was incorporated into the mixture solution and stirred continuously for 1-6 h to obtain a uniform spinning precursor solution; (8) Transfer the spinning precursor solution to a plastic syringe for spinning, apply a voltage of 13-22 kV, and set the spinning solution flow rate to 0.1-1 mL·h. -1 ; (9) The collected nanofibers were placed in a muffle furnace for pre-oxidation for 30-200 min, with a heating rate of 1-10 ℃ / min and a pre-oxidation temperature of 100-500 ℃; (10) Subsequently, the pre-oxidized nanofibers are placed in one of the atmospheres of argon, nitrogen or hydrogen and kept at a temperature of 400-1000 ℃ for 30-200 min, with a heating rate of 1-10 ℃ / min, to obtain HEAs-loaded carbon fiber materials. (11) Disperse it in 10 mL of deionized water by ultrasonication for 3-20 min, freeze it with liquid nitrogen for 30-180 s, and then freeze-dry it for 6-24 h to obtain HEAs-supported carbon fiber aerogel electrocatalytic material.

[0007] Wherein: the mass of zinc source in step (1) is 2-20 g; the mass of 2-methylimidazole in step (2) is 2-20 g; the mass of polyacrylonitrile in step (5) is 0.05-0.5 g, and the volume of spinning solvent is 3 mL; the amount of metal in the spinning solution in step (6) is 0.04-0.9 mmol, and the mass of ZIF-8 powder added in step (7) is 0.01-0.3 g.

[0008] As a further optimization of this scheme, the zinc source in step (1) is one of zinc nitrate hexahydrate, zinc acetate, zinc chloride, and zinc sulfate.

[0009] As a further optimization of this scheme, the alcohol in steps (1), (2) and (3) is one of methanol, ethanol, propanol, isopropanol and butanol.

[0010] As a further optimization of this scheme, the platinum salt mentioned in step (6) is one of chloroplatinic acid, platinum nitrate, and platinum sulfate; the copper salt is one of copper chloride trihydrate, copper nitrate pentahydrate, copper sulfate, and copper carbonate; the nickel salt is one of nickel chloride hexahydrate, nickel nitrate, nickel sulfate, and nickel nitrite; the cobalt salt is one of cobalt chloride hexahydrate, cobalt acetate, cobalt sulfate, and cobalt nitrate; the manganese salt is one of manganese chloride, manganese sulfate, manganese chromate, and manganese carbonate; and the iron salt is one of ferric chloride hexahydrate, ferric nitrate, ferric sulfate, ferrous sulfate, and ferric hydroxide.

[0011] As a further optimization of this scheme, in step (3), the water bath temperature is 20-80 ℃, the centrifugation speed is 1000-8000 r / min, and the centrifugation time is 2-15 min.

[0012] As a further optimization of this scheme, the spinning solvent mentioned in step (5) is one of N,N-dimethylformamide, N,N-dimethylacetamide or dimethyl sulfoxide.

[0013] As a further optimization of this scheme, the freeze-drying temperature in step (11) is -60 to -5 ℃, and the drying time is 8 to 40 h.

[0014] The method of this invention and the HEAs-supported carbon fiber aerogel prepared by this method for use in electrocatalysis have the following characteristics: (1) The process is simple, the cost is low and the energy consumption is low. Electrospinning technology is used to enhance the strength of carbon fibers by anchoring metal loads with ZIF-8. HEAs-loaded carbon fiber aerogels can then be obtained through a low-cost and safe freeze-drying method.

[0015] (2) The material has excellent electrical conductivity, low precious metal loading density, low cost, and integrates high catalytic activity and high stability.

[0016] (3) The HEAs-supported carbon fiber aerogel prepared by this method exhibits excellent electrocatalytic activity and stability in a variety of electrocatalytic fields, which is of positive significance for realizing the industrial application of electrocatalytic materials that combine metal and carbon support. Attached Figure Description

[0017] Figure 1 This is the XRD pattern of the HEAs-supported carbon fiber aerogel prepared in Example 1.

[0018] Figure 2 This is a SEM image of the HEAs-loaded carbon fiber aerogel prepared in Example 2.

[0019] Figure 3 This is an image showing the elemental distribution of the HEAs-supported carbon fiber aerogel prepared in Example 2. Detailed Implementation

[0020] The present invention will be further illustrated below by way of examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make any alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0021] Example 1 2 g of zinc nitrate hexahydrate was dissolved in 200 mL of methanol to form a homogeneous solution A. Then, 2 g of 2-methylimidazole was dissolved in 200 mL of methanol to form a homogeneous solution B. Solutions A and B were mixed and stirred in a 20 °C water bath to obtain a homogeneous suspension. The product was collected by centrifugation and washed with methanol at 1000 r / min for 15 min. The washed product was dried in an oven for 1 h to obtain ZIF-8 nanoparticles. 0.05 g of polyacrylonitrile was added to 3 mL of N,N-dimethylformamide and stirred for 2 h to dissolve and form a homogeneous and transparent spinning solution. Equimolar amounts of palladium chloride, platinum nitrate, manganese chloride, nickel nitrate, and cobalt chloride hexahydrate (0.04 mmol total) were dissolved in the spinning solution and stirred for 20 min to obtain a mixed solution. Then, 0.01 g of ZIF-8 powder was incorporated into the mixed solution, and stirring was continued for 1 h to obtain a homogeneous spinning precursor solution. The spinning precursor solution was transferred to a plastic syringe for spinning, with an applied voltage of 13 kV and a spinning solution flow rate of 0.1 mL·h. -1 The collected nanofibers were pre-oxidized in a muffle furnace for 30 min at a heating rate of 10 °C / min to a pre-oxidation temperature of 500 °C. Subsequently, the pre-oxidized nanofibers were placed under an argon atmosphere and held at 1000 °C for 30 min at a heating rate of 10 °C / min to obtain HEAs-supported carbon fiber material. This material was then dispersed in 10 mL of deionized water by ultrasonication for 3 min and frozen in liquid nitrogen for 30 s. Following this, it was freeze-dried for 6 h at -60 °C to obtain HEAs-supported carbon fiber aerogel electrocatalytic material. Testing revealed that its BET specific surface area reached 363 m². 2 / g, half-wave potential 0.86 V vs. RHE, stability lasted for 20 h. Figure 1 The XRD pattern of the prepared HEAs-supported carbon fiber aerogel shows that the diffraction peaks indicate a PdCo-dominated face-centered cubic crystal structure.

[0022] Example 2 6.5 g of zinc chloride was dissolved in 200 mL of ethanol to form a homogeneous solution A. Subsequently, 5.8 g of 2-methylimidazole was dissolved in 200 mL of ethanol to form a homogeneous solution B. Solutions A and B were mixed and stirred in a 39 °C water bath to obtain a homogeneous suspension. The product was collected by centrifugation and washed with ethanol at 2500 r / min for 12 min. The washed product was dried in an oven for 3 h to obtain ZIF-8 nanoparticles. 0.15 g of polyacrylonitrile was added to 3 mL of N,N-dimethylacetamide and stirred for 5.8 h to dissolve and form a homogeneous and transparent spinning solution. Equivalent amounts of palladium chloride, platinum nitrate, ferric chloride, manganese chloride, and cobalt chloride hexahydrate (0.16 mmol total) were dissolved in the spinning solution and stirred for 50 min to obtain a mixed solution. Subsequently, 0.13 g of ZIF-8 powder was incorporated into the mixed solution, and stirring was continued for 2.1 h to obtain a homogeneous spinning precursor solution. The spinning precursor solution was transferred to a plastic syringe for spinning, with an applied voltage of 16 kV and a spinning solution flow rate of 0.37 mL·h. -1 The collected nanofibers were pre-oxidized in a muffle furnace for 60 min at a heating rate of 8 °C / min to a pre-oxidation temperature of 350 °C. Subsequently, the pre-oxidized nanofibers were placed under an argon atmosphere and held at 800 °C for 80 min at a heating rate of 7 °C / min to obtain HEAs-supported carbon fiber material. This material was then dispersed in 10 mL of deionized water by ultrasonication for 8 min and frozen in liquid nitrogen for 60 s. Following this, it was freeze-dried for 10 h at -30 °C to obtain HEAs-supported carbon fiber aerogel electrocatalytic material. Testing revealed that its BET specific surface area reached 542 m². 2 / g, half-wave potential 0.9 V vs. RHE, stability lasting 100 h. Figure 2 The image shows a SEM image of a carbon fiber aerogel loaded with HEAs, revealing a three-dimensional network porous aerogel structure composed of carbon fibers, with alloy particles uniformly distributed on the carbon fibers.

[0023] Example 3 12.3 g of zinc acetate was dissolved in 200 mL of propanol to form a homogeneous solution A. Subsequently, 14.9 g of 2-methylimidazole was dissolved in 200 mL of propanol to form a homogeneous solution B. Solutions A and B were mixed and stirred in a 65 °C water bath to obtain a homogeneous suspension. The product was collected by centrifugation and washed with propanol at 5000 r / min for 8 min. The washed product was dried in an oven for 4 h to obtain ZIF-8 nanoparticles. 0.38 g of polyacrylonitrile was added to 3 mL of N,N-dimethylformamide and stirred for 9 h to dissolve and form a homogeneous and transparent spinning solution. Equimolar amounts of palladium chloride, platinum nitrate, copper chloride, nickel chloride, and cobalt chloride hexahydrate (0.54 mmol total) were dissolved in the spinning solution and stirred for 120 min to obtain a mixed solution. Subsequently, 0.21 g of ZIF-8 powder was incorporated into the mixed solution, and stirring was continued for 4.5 h to obtain a homogeneous spinning precursor solution. The spinning precursor solution was transferred to a plastic syringe for spinning, with an applied voltage of 19 kV and a spinning solution flow rate of 0.68 mL·h. -1 The collected nanofibers were pre-oxidized in a muffle furnace for 130 min at a heating rate of 5 °C / min to a pre-oxidation temperature of 200 °C. Subsequently, the pre-oxidized nanofibers were placed under a nitrogen atmosphere and held at 600 °C for 120 min at a heating rate of 5 °C / min to obtain HEAs-supported carbon fiber material. This material was then dispersed in 10 mL of deionized water by ultrasonication for 13 min and frozen in liquid nitrogen for 100 s. Following this, it was freeze-dried for 16 h at -20 °C to obtain HEAs-supported carbon fiber aerogel electrocatalytic material. Testing revealed that its BET specific surface area reached 458 m². 2 / g, half-wave potential 0.85 V vs. RHE, stability lasted for 52 h. Figure 3 The image shows the elemental distribution of HEAs-loaded carbon fiber aerogel. Each element is uniformly distributed in a single nanoparticle, with no obvious elemental segregation or phase separation.

[0024] Example 4 20 g of zinc sulfate was dissolved in 200 mL of isopropanol to form a homogeneous solution A. Then, 20 g of 2-methylimidazole was dissolved in 200 mL of methanol to form a homogeneous solution B. Solutions A and B were mixed and stirred in an 80 °C water bath to obtain a homogeneous suspension. The product was collected by centrifugation and washed with methanol at 8000 r / min for 2 min. The washed product was dried in an oven for 6 h to obtain ZIF-8 nanoparticles. 0.5 g of polyacrylonitrile was added to 3 mL of dimethyl sulfoxide and stirred for 12 h to dissolve and form a homogeneous and transparent spinning solution. Equimolar amounts of palladium chloride, platinum nitrate, copper chloride, ferric chloride, and cobalt chloride hexahydrate (0.9 mmol total) were dissolved in the spinning solution and stirred for 180 min to obtain a mixed solution. Then, 0.3 g of ZIF-8 powder was incorporated into the mixed solution, and stirring was continued for 6 h to obtain a homogeneous spinning precursor solution. The spinning precursor solution was transferred to a plastic syringe for spinning, with an applied voltage of 22 kV and a spinning solution flow rate of 1 mL·h. -1 The collected nanofibers were pre-oxidized in a muffle furnace for 200 min at a heating rate of 1 °C / min and a pre-oxidation temperature of 100 °C. Subsequently, the pre-oxidized nanofibers were placed in a hydrogen atmosphere and held at 400 °C for 200 min at a heating rate of 1 °C / min to obtain HEAs-supported carbon fiber material. This material was then dispersed in 10 mL of deionized water by ultrasonication for 20 min and frozen in liquid nitrogen for 180 s. Following this, it was freeze-dried for 24 h at -5 °C to obtain HEAs-supported carbon fiber aerogel electrocatalytic material. Testing revealed that its BET specific surface area reached 275 m². 2 / g, half-wave potential 0.87V vs. RHE, stability lasted for 36 h.

[0025]

[0026] In summary, the HEAs-supported carbon fiber aerogel electrocatalyst in Example 2 exhibits superior physical properties and electrocatalytic performance, thus Example 2 represents the optimal result of this invention.

[0027] The basic teachings of the invention have been described, and many extensions and variations will be readily apparent to those skilled in the art. Since the invention disclosed in the specification can be practiced in other specific forms without departing from the spirit or general characteristics of the invention, and some of these specific forms have been pointed out, the embodiments disclosed in the specification should be considered illustrative rather than limiting. The scope of the invention is defined by the appended claims, not by the foregoing description, and all modifications of equal meaning and scope falling within the claims are included within their scope.

Claims

1. A method for preparing a high-entropy alloy-supported carbon fiber aerogel catalytic material, characterized in that, The specific steps of the preparation method are as follows: (1) Dissolve a certain amount of zinc source in 200 mL of alcohol to form a homogeneous solution A; (2) Subsequently, a certain amount of 2-methylimidazole was dissolved in 200 mL of alcohol to form a homogeneous solution B; (3) Mix solutions A and B and stir under water bath conditions to obtain a uniform suspension. After centrifugation, collect the product and wash it with alcohol. (4) The washed product was placed in an oven and dried for 1-6 h to finally obtain ZIF-8 nanoparticles; (5) Add polyacrylonitrile to the spinning solvent and stir for 2-12 h to dissolve and form a uniform and transparent spinning solution; (6) Dissolve five metal salts in equal amounts in the spinning solution and stir for 20-180 min to obtain a mixed solution; The metal salt is formed by mixing any four of the following: platinum salt, copper salt, nickel salt, cobalt salt, manganese salt, and iron salt with palladium chloride; (7) Subsequently, the synthesized ZIF-8 powder was incorporated into the mixture solution and stirred continuously for 1-6 h to obtain a uniform spinning precursor solution; (8) Transfer the spinning precursor solution to a plastic syringe for spinning, apply a voltage of 13-22 kV, and set the spinning solution flow rate to 0.1-1 mL·h. -1 ; (9) The collected nanofibers were placed in a muffle furnace for pre-oxidation for 30-200 min, with a heating rate of 1-10 ℃ / min and a pre-oxidation temperature of 100-500 ℃; (10) Subsequently, the pre-oxidized nanofibers are placed in one of the atmospheres of argon, nitrogen or hydrogen and kept at a temperature of 400-1000 ℃ for 30-200 min, with a heating rate of 1-10 ℃ / min, to obtain HEAs-loaded carbon fiber materials. (11) Disperse it in 10 mL of deionized water by ultrasonication for 3-20 min, freeze it with liquid nitrogen for 30-180 s, and then freeze-dry it to obtain HEAs-supported carbon fiber aerogel electrocatalytic material. Wherein: the mass of zinc source in step (1) is 2-20 g; the mass of 2-methylimidazole in step (2) is 2-20 g; the mass of polyacrylonitrile in step (5) is 0.05-0.5 g, and the volume of spinning solvent is 3 mL; the amount of metal in the spinning solution in step (6) is 0.04-0.9 mmol, and the mass of ZIF-8 powder added in step (7) is 0.01-0.3 g.

2. The preparation method according to claim 1, characterized in that... In step (1), the zinc source is one of zinc nitrate hexahydrate, zinc acetate, zinc chloride, or zinc sulfate.

3. The method for preparing a high-entropy alloy-supported carbon fiber aerogel catalytic material according to claim 1, characterized in that, In steps (1), (2) and (3), the alcohol is one of methanol, ethanol, propanol, isopropanol and butanol.

4. The method for preparing a high-entropy alloy-supported carbon fiber aerogel catalytic material according to claim 1, characterized in that, The platinum salt mentioned in step (6) is one of chloroplatinic acid, platinum nitrate, and platinum sulfate; the copper salt is one of copper chloride trihydrate, copper nitrate pentahydrate, copper sulfate, and copper carbonate; the nickel salt is one of nickel chloride hexahydrate, nickel nitrate, nickel sulfate, and nickel nitrite; the cobalt salt is one of cobalt chloride hexahydrate, cobalt acetate, cobalt sulfate, and cobalt nitrate; the manganese salt is one of manganese chloride, manganese sulfate, manganese chromate, and manganese carbonate; and the iron salt is one of ferric chloride hexahydrate, ferric nitrate, ferric sulfate, ferrous sulfate, and ferric hydroxide.

5. The method for preparing a high-entropy alloy-supported carbon fiber aerogel catalytic material according to claim 1, characterized in that, In step (3), the water bath temperature is 20-80 ℃, the centrifugation speed is 1000-8000 r / min, and the centrifugation time is 2-15 min.

6. The method for preparing a high-entropy alloy-supported carbon fiber aerogel catalytic material according to claim 1, characterized in that, The spinning solvent mentioned in step (5) is one of N,N-dimethylformamide, N,N-dimethylacetamide or dimethyl sulfoxide.

7. The method for preparing a high-entropy alloy-supported carbon fiber aerogel catalytic material according to claim 1, characterized in that, In step (11), the freeze-drying temperature is -60~-5℃ and the drying time is 8-40 h.

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