A method for preparing FePt-based high-entropy alloy nanoparticles by a strong magnetic field assisted wet chemical method

Abstract

The application belongs to the technical field of high-entropy nanomaterials, and particularly relates to a method for preparing FePt-based high-entropy alloy nanoparticles by a strong magnetic field assisted wet chemical method. A certain amount and proportion of Fe, Pt and additive element X metal precursors, a reducing agent and a surfactant are added into a solvent under a strong magnetic field. After being mixed uniformly under the protection of an inert atmosphere, water removal treatment is performed, then heating is performed at a certain heating rate until a target temperature, and after being kept warm, cooling is performed until room temperature. The obtained black mixed solution is cleaned, centrifuged and vacuum dried. Finally, FePt-based high-entropy alloy nanoparticles with uniform composition and small particle size are prepared. In the experiment process, the strong magnetic field is introduced into the wet chemical synthesis, the reduction speed of the metal precursors can be controlled, the co-reduction of metals with different reduction potentials is realized, the FePt-based high-entropy alloy nanoparticles with uniform composition are obtained, and then excellent water electrolysis hydrogen evolution performance is obtained.

Description

Technical Field

[0001] This invention belongs to the field of high-entropy nanomaterials technology, specifically relating to a method for preparing FePt-based high-entropy alloy nanoparticles by a strong magnetic field-assisted wet chemical process. Background Technology

[0002] FePt-based high-entropy alloy nanoparticles possess excellent catalytic performance, high thermal stability, and good biocompatibility, and are widely used as electrocatalysts, thermal catalysts, wastewater treatment materials, and contrast agents. The superior functional properties of FePt-based high-entropy alloy nanoparticles are closely related to their morphology, size, and phase structure. In particular, FePt-based high-entropy alloy nanoparticles with large specific surface area and uniform elemental composition / phase distribution exhibit superior catalytic activity and stability, and will play an important role in energy conversion devices and membrane electrode technology for electrocatalytic reactions such as hydrogen evolution reaction, oxygen evolution reaction, and oxygen reduction reaction. Currently, various methods for preparing FePt-based high-entropy alloy nanoparticles have been developed, including carbon-isolated heat treatment, thermal shock, high-temperature sulfur anchoring, and impregnation reduction. However, regardless of whether it is a brief thermal shock or the adjustment of the isolating medium, high heat treatment temperatures inevitably lead to nanoparticle aggregation, phase separation, and loss of surface activity, resulting in reduced catalytic activity and stability. The main reason is that FePt-based high-entropy alloy nanoparticles have a bottleneck that is difficult to overcome: the reduction potentials of different elements in the high-entropy alloy are different, making it difficult to reduce them simultaneously, which makes it difficult to prepare FePt-based high-entropy alloy nanoparticles with uniform composition and fine particle size.

[0003] Wet chemical methods offer good controllability and produce nanoparticles with high surface activity, uniform particle size, and consistent morphology, making them an important approach for preparing nanocatalysts. However, this method also has drawbacks such as phase separation and a relatively wide particle size distribution. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for preparing FePt-based high-entropy alloy nanoparticles using a strong magnetic field-assisted wet chemical process. The aim is to introduce a strong magnetic field-assisted wet chemical method to prepare FePt-based high-entropy alloy nanoparticles with fine particle size, good dispersibility, and uniform composition. During the wet chemical reaction, the Lorentz force under the influence of the strong magnetic field effectively reduces the energy barrier for metal ion diffusion, improves the uniformity of metal ion diffusion in the liquid solution, and forms a magnetohydrodynamic effect. The magnetization energy generated by the magnetohydrodynamics increases the collision frequency of free radicals in the liquid solution, compensating for the reduction potential difference between different metal precursors, thereby achieving co-reduction of different metal precursors to obtain FePt-based high-entropy alloy nanoparticles with uniform composition. The FePt-based high-entropy alloy nanoparticles synthesized by this method are characterized by uniform morphology and size, and uniform composition. The composition, size, and morphology of the FePt-based high-entropy alloy nanoparticles can be controlled by adjusting the magnetic field strength, the types of metal precursors / reducing agents / surfactants / solvents, the ratio of reducing agents / surfactants / solvents, the reaction temperature, and the reaction time, thereby effectively improving the electrocatalytic activity.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing FePt-based high-entropy alloy nanoparticles using a strong magnetic field-assisted wet chemical process includes the following steps: Step (1): Mole ratio Fe : Pt : X1 : X2 : … : X n = (0.1~1.0) : (0.1~1.0) : (0.03~0.3) : (0.03~0.3) : … : (0.03~0.3) (3 ≤ n ≤ 10) Weigh Fe, Pt and X metal precursors, where X is an added element; then weigh the reducing agent according to a molar ratio of reducing agent to metal precursor of 1.0~2.0; Step (2): Mix the weighed reducing agent and metal precursor with the solvent, then add the surfactant, and prepare a black mixed solution by heating in two stages under the protection of a strong magnetic field of 1.0~6.0 T and an inert atmosphere: first heat to 100~120℃ at a heating rate of 3~10 ℃ / min and hold for 30~60 min, then heat to 260~360℃ at a heating rate of 3~10℃ / min and hold for 60~300 min before cooling to room temperature; Step (3): The obtained black mixed solution is washed with a low-boiling-point solvent and collected by centrifugation at a speed of 2000~12000 r / min for 3~10 min. After centrifugation, the upper layer of centrifuged liquid is discarded, and the obtained precipitate is centrifuged 3~6 times. Finally, the obtained black precipitate is vacuum dried at 60~80℃ for 12~24 h to obtain black powder, which is FePt-based high-entropy alloy nanoparticles with an average particle size of 2.0~20.0 nm and all phases are FePt phase.

[0006] Furthermore, in the above-mentioned method for preparing FePt-based high-entropy alloy nanoparticles by strong magnetic field-assisted wet chemical method, in step (1), the Fe metal precursor is selected from one of ferric acetylacetone, ferric chloride, ferric sulfate, ferric acetate, or ferric nitrate; the Pt metal precursor is selected from one of platinum acetylacetone, chloroplatinic acid, potassium chloroplatinate, or sodium chloroplatinate; the X metal precursor is selected from one of acetylacetone, chloride, sulfate, or nitrate salts, and the corresponding X element is 3 to 10 of the elements Cu, Mn, Co, Ni, Zn, Cr, Sn, Bi, Pb, Sb, Te, Ag, Au, Ru, Pd, Rh, Ir, Mo, La, Sm, and Ce.

[0007] Furthermore, in the above-mentioned method for preparing FePt-based high-entropy alloy nanoparticles by strong magnetic field-assisted wet chemical method, the reducing agent in step (1) is selected from one of sodium borohydride, ascorbic acid, hydrazine hydrate, sodium citrate, sodium hypophosphite, 1,2-hexadecanediol, and dimethylacetamide.

[0008] Furthermore, in the above-mentioned method for preparing FePt-based high-entropy alloy nanoparticles by strong magnetic field-assisted wet chemical method, in step (2), the solvent is selected from one of diphenyl ether, hydrogenated terphenyl, perfluoropolyether, hexadecylamine, octadecylamine, and trioctylamine, and the molar ratio of the solvent to the metal precursor powder + reducing agent is (20~80):1, with the unit being mmol:mmol.

[0009] Furthermore, in the above-mentioned method for preparing FePt-based high-entropy alloy nanoparticles by strong magnetic field-assisted wet chemical method, in step (2), the surfactant is selected from two of the following: polyether ether ketone, perfluoropolyether ammonium hydroxide, polyvinylpyrrolidone, sodium polyacrylate, oleylamine, oleic acid, stearic acid, and oleamide. The volume ratio of the two surfactants is (1~10): (1~10); and the molar ratio of surfactant to solvent is (0.1~0.5): 1.0, with units of mmol: mmol.

[0010] Furthermore, in the above-mentioned method for preparing FePt-based high-entropy alloy nanoparticles by strong magnetic field-assisted wet chemical method, the inert atmosphere in step (2) is selected from one of the following atmospheres: 95%Ar + 5%H2, 93%Ar + 7%H2, high-purity nitrogen or high-purity argon.

[0011] Furthermore, in the above-mentioned method for preparing FePt-based high-entropy alloy nanoparticles by strong magnetic field-assisted wet chemical method, in step (3), the low-boiling-point solvent is selected from one of n-hexane, petroleum ether, chloroform, ethanol, methyl ether, and cyclohexanone, and the volume ratio of the black mixed solution to the low-boiling-point solvent during cleaning is 1: (2~20).

[0012] Furthermore, in the above-mentioned method for preparing FePt-based high-entropy alloy nanoparticles by strong magnetic field-assisted wet chemical method, the FePt-based high-entropy alloy nanoparticles obtained in step (3) exhibit excellent performance in the electrocatalytic hydrogen evolution reaction, with an overpotential of 5~40 mV at 10 mA / cm².

[0013] Furthermore, in the above-mentioned method for preparing FePt-based high-entropy alloy nanoparticles by strong magnetic field-assisted wet chemical method, the morphology and elemental distribution of the FePt-based high-entropy alloy nanoparticles obtained in step (3) are characterized by field emission transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS); the phase composition is confirmed by X-ray diffraction (XRD); and the electrocatalytic hydrogen evolution performance is evaluated by an electrochemical workstation.

[0014] Advantages and beneficial effects of the present invention: (1) By using strong magnetic field technology, the uniform diffusion and co-reduction of metal ions are promoted through Lorentz force and magnetohydrodynamic effect, thereby obtaining nanoparticles with uniform composition. This solves the problem caused by the difference in reduction potential of different metals in traditional methods.

[0015] (2) Using specific heating rates, temperatures and inert atmospheres to reduce high-temperature treatment time and avoid phase separation and aggregation, thereby maintaining the small size and dispersibility of nanoparticles; at the same time, the selection and ratio of surfactants can control the morphology.

[0016] (3) The uniform composition and high entropy alloy nanoparticles have excellent catalytic activity, thermal stability and application potential, and are expected to improve efficiency and stability in electrocatalytic reactions.

[0017] (4) This method has advantages in simplifying the process, reducing costs and being environmentally friendly. It reduces the high-temperature heat treatment steps and saves energy. This invention will promote the practical application of high-entropy alloy nanocatalysts and has broad theoretical and application significance. Attached Figure Description

[0018] Figure 1TEM image (a) and particle size distribution (b) of the FePt-based high-entropy alloy nanoparticles prepared in Example 1; Figure 2 The elemental distribution diagram of the FePt-based high-entropy alloy nanoparticles prepared in Example 1 is shown. Figure 3 The electrocatalytic hydrogen evolution performance (a) of the FePt-based high-entropy alloy nanoparticles prepared in Example 1 in 1.0 M KOH and at 10 mA·cm⁻¹ -2 20 mA·cm -2 and 40 mA·cm -2 Overpotential below; Figure 4 The XRD pattern of the FePt-based high-entropy alloy nanoparticles prepared in Example 1; Figure 5 TEM image (a) and particle size distribution (b) of the FePt-based high-entropy alloy nanoparticles prepared in Example 2; Figure 6 The elemental distribution diagram of the FePt-based high-entropy alloy nanoparticles prepared in Example 2 is shown below. Figure 7 The electrocatalytic hydrogen evolution performance (a) of the FePt-based high-entropy alloy nanoparticles prepared in Example 2 in 1.0 M KOH and at 10 mA·cm⁻¹ -2 20 mA·cm -2 and 40 mA·cm -2 Overpotential below; Figure 8 The XRD pattern of the FePt-based high-entropy alloy nanoparticles prepared in Example 2; Figure 9 TEM image (a) and particle size distribution (b) of the FePt-based high-entropy alloy nanoparticles prepared in Example 3. Detailed Implementation

[0019] This invention employs a strong magnetic field-assisted wet chemical method to prepare small-sized, uniformly composed FePt-based high-entropy alloy nanoparticles. Under a strong magnetic field, a certain amount and proportion of Fe, Pt, and additive element X metal precursor, reducing agent, and surfactant are added to a solvent. After homogenization under an inert atmosphere, the mixture undergoes dehydration treatment, followed by heating to a target temperature at a controlled rate, holding at that temperature, and then cooling to room temperature. The resulting black mixed solution is washed, centrifuged, and vacuum dried. This process ultimately yields uniformly composed, small-sized FePt-based high-entropy alloy nanoparticles. During the experiment, introducing a strong magnetic field into the wet chemical synthesis allows for the control of the reduction rate of the metal precursor, enabling co-reduction of metals at different reduction potentials, resulting in uniformly composed FePt-based high-entropy alloy nanoparticles, and consequently, excellent hydrogen evolution performance in water electrolysis.

[0020] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be used to limit the scope of the present invention.

[0021] The equipment involved in the following examples is all commercially available and can be purchased from the market. The equipment includes: a magnetic stirrer, an electronic balance, a centrifuge, a strong magnetic field, a vacuum drying oven, a three-necked flask, and a condenser. The magnetic stirrer is model ZNCL-TS, the electronic balance is model Mettler AE50, the centrifuge is model HC-2066, the strong magnetic field is model JMTD-12 T, the vacuum drying oven is model DZF-6020, the electrochemical workstation is model Bio-Logic VSP, and the three-necked flask and condenser are commercially available products.

[0022] The following examples use ferric acetylacetone, ferric chloride, ferric sulfate, ferric acetate, ferric nitrate, platinum acetylacetone, chloroplatinic acid, potassium chloroplatinate, sodium chloroplatinate, X metal precursor salts (Cu, Mn, Co, Ni, Zn, Cr, Sn, Bi, Pb, Sb, Te, Ag, Au, Ru, Pd, Rh, Ir, Mo, La, Sm, Ce, where X metal precursor salts include acetylacetone salts, chloride salts, sulfate salts, and nitrate salts), sodium borohydride, ascorbic acid, hydrazine hydrate, sodium citrate, sodium hypophosphite, 1,2-hexadecanediol, dimethylacetamide, diphenyl ether, hydrogenated terphenyl, perfluoropolyether, hexadecylamine, octadecylamine, trioctylamine, polyetheretherketone, perfluoropolyether ammonium hydroxide, polyvinylpyrrolidone, sodium polyacrylate, oleylamine, oleic acid, stearic acid, oleamide, a hydrogen-argon mixture (95% Ar + 5% H2), and a hydrogen-argon mixture (93% Ar + 5% H2). 7% H2), high-purity nitrogen and high-purity argon, n-hexane, petroleum ether, chloroform, ethanol, methyl ether and cyclohexanone were all commercially available products purchased from the market.

[0023] Example 1. This embodiment describes a method for preparing FePt-based high-entropy alloy nanoparticles using a strong magnetic field-assisted wet chemical method, comprising the following steps: First, 0.5 mmol of iron acetylacetone as the Fe metal precursor and 0.5 mmol of platinum acetylacetone as the Pt metal precursor were weighed using an electronic balance. Then, 0.2 mmol of each of the four additive element X metal precursors (X being Cu, Ni, Ru, and Ag) were weighed; all X metal precursors were acetylacetone salts. Next, 1,2-hexadecanediol, the reducing agent, was weighed, with a molar ratio of reducing agent to metal precursor of 1.0.

[0024] Under a magnetic field strength of 1.0 T, a hydrogen-argon mixture of 93% Ar + 5% H2 was used as the protective atmosphere. The weighed reducing agent, metal precursor, and surfactants (oleylamine and oleic acid) were added to a hexadecylamine solvent. The molar ratio of solvent to (metal precursor powder + reducing agent) was 20; the volume ratio of the two surfactants was 1:1; and the molar ratio of surfactant to solvent was 0.2. After thorough mixing, the solution was heated to 100℃ at a heating rate of 3℃ / min and held at this temperature for 30 min. Then, it was heated to 360℃ at a rate of 3℃ / min and held for 180 min before cooling to room temperature.

[0025] The obtained black mixed solution was then washed with the low-boiling-point solvent n-hexane and collected by centrifugation. The volume ratio of the black mixed solution to the low-boiling-point solvent was 1:2. The centrifugation speed was 2000 r / min, and the centrifugation time was 3 min. After centrifugation, the supernatant was discarded, and the resulting precipitate was centrifuged three times. Finally, the obtained black precipitate was vacuum dried at 60℃ for 12 h to obtain a black powder, which is the FePt-based high-entropy alloy nanoparticle.

[0026] Field emission transmission electron microscopy (TEM) revealed that the particles were spherical, uniform in morphology, and well-dispersed, as shown in the attached image. Figure 1 As shown in (a); the average particle size of the product is 3.67 nm, and the particle size distribution is shown in the attached figure. Figure 1 As shown in (b). The elemental distribution of the product was characterized using TEM and accompanying EDS, as shown in the appendix. Figure 2 As shown, all elements are uniformly distributed on the nanoparticles, with no elemental segregation. The catalytic performance of the product hydrogen evolution reaction was evaluated using an electrochemical workstation, as shown in the attached figure. Figure 3 As shown, its overpotential at 10 mA / cm² is 33.8 mV, significantly better than that of commercial Pt / C catalysts (41.7 mV). XRD measurements of the samples are shown in the attached figure. Figure 4 As shown, the positions of the diffraction peaks are significantly different compared to pure Fe, Pt, Cu, Ni, Ru, and Ag, and compared to... fcc The standard spectrum of the FePt phase (PDF#290718) is shifted 0.26° to the right, indicating that FePt-based high-entropy alloy nanoparticles were successfully synthesized.

[0027] Example 2 This embodiment describes a method for preparing FePt-based high-entropy alloy nanoparticles using a strong magnetic field-assisted wet chemical process, comprising the following steps: First, 0.25 mmol of iron acetylacetone as the Fe metal precursor and 0.25 mmol of platinum acetylacetone as the Pt metal precursor were weighed using an electronic balance. Then, 0.1 mmol of each of the four additive element X metal precursors (X being Cu, Co, Ru, and Ag) were weighed; all X metal precursors were acetylacetone salts. Next, sodium borohydride, the reducing agent, was weighed, with a molar ratio of reducing agent to metal precursors of 1.2.

[0028] Under a magnetic field strength of 3.0 T, a hydrogen-argon mixture of 93% Ar + 7% H2 was used as the protective atmosphere. The weighed reducing agent, metal precursor, and surfactants (oleylamine and oleic acid) were added to a hexadecylamine solvent. The molar ratio of solvent to (metal precursor powder + reducing agent) was 50; the volume ratio of the two surfactants was 5:5; and the molar ratio of surfactant to solvent was 0.1. After thorough mixing, the solution was heated to 110℃ at a heating rate of 5℃ / min and held at this temperature for 45 min. Then, it was heated to 340℃ at a rate of 5℃ / min and held for 200 min before cooling to room temperature.

[0029] The obtained black mixed solution was then washed with the low-boiling-point solvent petroleum ether and collected by centrifugation. The volume ratio of the black mixed solution to the low-boiling-point solvent was 1:20. The centrifugation speed was 12000 r / min, and the centrifugation time was 10 min. After centrifugation, the supernatant was discarded, and the resulting precipitate was centrifuged six times. Finally, the obtained black precipitate was vacuum dried at 80℃ for 24 h to obtain a black powder, which is the high-entropy alloy nanoparticle.

[0030] Field emission transmission electron microscopy (TEM) revealed that the particles were spherical, uniform in morphology, and well-dispersed, as shown in the attached image. Figure 5 As shown in (a); the average particle size of the product is 4.34 nm, and the particle size distribution is shown in the attached figure. Figure 5 As shown in (b). The elemental distribution of the product was characterized using TEM and accompanying EDS, as shown in the appendix. Figure 6 As shown, all elements are uniformly distributed on the nanoparticles, with no elemental segregation. The catalytic performance of the product hydrogen evolution reaction was evaluated using an electrochemical workstation, as shown in the attached figure. Figure 7 As shown, its overpotential at 10 mA / cm² is 25.1 mV, significantly better than that of commercial Pt / C catalysts (41.7 mV). XRD measurements of the samples are shown in the attached figure. Figure 8 As shown, the positions of the diffraction peaks are significantly different compared to pure Fe, Pt, Cu, Co, Ru, and Ag, and compared to... fcc The standard spectrum of the FePt phase (PDF#290718) is shifted 0.28° to the right, indicating that FePt-based high-entropy alloy nanoparticles were successfully synthesized.

[0031] Example 3

[0032] This embodiment describes a method for preparing FePt-based high-entropy alloy nanoparticles using a strong magnetic field-assisted wet chemical process, comprising the following steps: First, 0.6 mmol of iron acetylacetone as the Fe metal precursor and 0.7 mmol of platinum acetylacetone as the Pt metal precursor were weighed using an electronic balance. Then, 0.3 mmol of each of the four additive element X metal precursors (X being Ni, Co, Ru, and Ag) were weighed; all X metal precursors were acetylacetone salts. Next, hydrazine hydrate, the reducing agent, was weighed, with a molar ratio of reducing agent to metal precursors of 1.4.

[0033] Under a magnetic field strength of 4.0 T, high-purity nitrogen was used as the protective atmosphere. The weighed reducing agent, metal precursor, and surfactants (polyetheretherketone and sodium polyacrylate) were added to a trioctylamine solvent. The molar ratio of solvent to (metal precursor powder + reducing agent) was 80; the volume ratio of the two surfactants was 10:10; and the molar ratio of surfactant to solvent was 0.5. After thorough mixing, the solution was heated to 120°C at a heating rate of 10°C / min and held at this temperature for 60 min. Then, it was heated to 330°C at a rate of 10°C / min and held for 300 min before cooling to room temperature.

[0034] The obtained black mixed solution was then washed with the low-boiling-point solvent dimethyl ether and collected by centrifugation. The volume ratio of the black mixed solution to the low-boiling-point solvent was 1:15. The centrifugation speed was 8000 r / min, and the centrifugation time was 8 min. After centrifugation, the supernatant was discarded, and the resulting precipitate was centrifuged four times. Finally, the obtained black precipitate was vacuum dried at 60℃ for 20 h to obtain a black powder, which is the FePt-based high-entropy alloy nanoparticle.

[0035] Field emission transmission electron microscopy (TEM) revealed that the particles were spherical, uniform in morphology, and well-dispersed, as shown in the attached image. Figure 9 As shown in (a); the average particle size of the product is 3.42 nm, and the particle size distribution is shown in the attached figure. Figure 9 As shown in (b). TEM-EDS characterization revealed that all elements were uniformly distributed on the nanoparticles without elemental segregation. The catalytic performance of the product for the hydrogen evolution reaction was evaluated using an electrochemical workstation, showing an overpotential of 13.6 mV at 10 mA / cm², significantly superior to the commercial Pt / C catalyst (41.7 mV). XRD measurements of the sample showed that the positions of the diffraction peaks were significantly different compared to those of each element, and compared to… fcc The standard spectrum of the FePt phase (PDF#290718) is shifted 0.24° to the right, indicating that FePt-based high-entropy alloy nanoparticles were successfully synthesized.

[0036] Example 4

[0037] This embodiment describes a method for preparing FePt-based high-entropy alloy nanoparticles using a strong magnetic field-assisted wet chemical process, comprising the following steps: First, 0.1 mmol of ferric chloride as the Fe metal precursor and 0.1 mmol of chloroplatinic acid as the Pt metal precursor were weighed using an electronic balance. Then, 0.03 mmol of each of the four added element X metal precursors (X being Sn, Te, Ru, and Pd) were weighed; all X metal precursors were chloride salts. Next, sodium citrate, the reducing agent, was weighed, with a molar ratio of reducing agent to metal precursors of 1.5.

[0038] Under a magnetic field strength of 2.0 T, a hydrogen-argon mixture of 95% Ar + 5% H2 was used as the protective atmosphere. The weighed reducing agent, metal precursor, and surfactants (stearic acid and oleamide) were added to an octadecylamine solvent. The molar ratio of solvent to (metal precursor powder + reducing agent) was 40; the volume ratio of the two surfactants was 3:7; and the molar ratio of surfactant to solvent was 0.5. After thorough mixing, the solution was heated to 118°C at a heating rate of 10°C / min and held at this temperature for 42 min. Then, it was heated to 340°C at a rate of 8°C / min and held for 270 min before cooling to room temperature.

[0039] The obtained black mixed solution was then washed with a low-boiling-point solvent, ethanol, and collected by centrifugation. The volume ratio of the black mixed solution to the low-boiling-point solvent was 1:10. The centrifugation speed was 10,000 r / min, and the centrifugation time was 5 min. After centrifugation, the supernatant was discarded, and the resulting precipitate was centrifuged five times. Finally, the obtained black precipitate was vacuum dried at 70℃ for 18 h to obtain a black powder, which is the FePt-based high-entropy alloy nanoparticle.

[0040] Field emission transmission electron microscopy (TEM) revealed that the particles were spherical, uniform in morphology, and well-dispersed; the average particle size was 2.0 nm. TEM-EDS characterization showed that all elements were uniformly distributed on the nanoparticles without elemental segregation. The catalytic performance of the product for the hydrogen evolution reaction was evaluated using an electrochemical workstation, showing an overpotential of 5.0 mV at 10 mA / cm². XRD measurements of the sample showed that the positions of the diffraction peaks were significantly different compared to those of each element. fcc The standard spectrum of the FePt phase (PDF#290718) is shifted 0.29° to the right, indicating that FePt-based high-entropy alloy nanoparticles were successfully synthesized.

[0041] Example 5: This embodiment describes a method for preparing FePt-based high-entropy alloy nanoparticles using a strong magnetic field-assisted wet chemical process, comprising the following steps: First, 1.0 mmol of ferric sulfate as the Fe metal precursor and 0.9 mmol of potassium chloroplatinate as the Pt metal precursor were weighed using an electronic balance. Then, 0.3 mmol of each of the four added element metal precursors (X being Mn, Co, Ni, and Ir) were weighed; all of these X metal precursors were sulfates. Next, sodium hypophosphite, the reducing agent, was weighed, with a molar ratio of reducing agent to metal precursors of 1.2.

[0042] Under a magnetic field strength of 1.0 T, a hydrogen-argon mixture of 95% Ar + 5% H2 was introduced as a protective atmosphere. The weighed reducing agent, metal precursor, and surfactants (polyetheretherketone and polyvinylpyrrolidone) were added to a perfluoropolyether solvent. The molar ratio of solvent to (metal precursor powder + reducing agent) was 20; the volume ratio of the two surfactants was 1:1; and the molar ratio of surfactant to solvent was 0.1. After thorough mixing, the solution was heated to 100℃ at a heating rate of 3℃ / min and held at this temperature for 60 min. Then, it was heated to 260℃ at a rate of 3℃ / min and held for 300 min before cooling to room temperature.

[0043] The obtained black mixed solution was then washed with the low-boiling-point solvent cyclohexanone and collected by centrifugation. The volume ratio of the black mixed solution to the low-boiling-point solvent was 1:5. The centrifugation speed was 6000 r / min, and the centrifugation time was 6 min. After centrifugation, the supernatant was discarded, and the resulting precipitate was centrifuged five times. Finally, the obtained black precipitate was vacuum dried at 80℃ for 16 h to obtain a black powder, which is the FePt-based high-entropy alloy nanoparticle.

[0044] Field emission transmission electron microscopy (TEM) revealed that the particles were spherical, uniform in morphology, and well-dispersed; the average particle size was 3.91 nm. TEM-EDS characterization showed that all elements were uniformly distributed on the nanoparticles without elemental segregation. The catalytic performance of the product for the hydrogen evolution reaction was evaluated using an electrochemical workstation, showing an overpotential of 10.9 mV at 10 mA / cm². XRD measurements of the sample showed that the diffraction peak positions were significantly different compared to the individual elements, and compared to… fcc The standard spectrum of the FePt phase (PDF#290718) is shifted 0.26° to the right, indicating that FePt-based high-entropy alloy nanoparticles were successfully synthesized.

[0045] Example 6: This embodiment describes a method for preparing FePt-based high-entropy alloy nanoparticles using a strong magnetic field-assisted wet chemical process, comprising the following steps: First, 0.4 mmol of ferric acetate as the Fe metal precursor and 0.5 mmol of platinum acetylacetonate as the Pt metal precursor were weighed using an electronic balance. Then, 0.15 mmol of each of the eight added element metal precursors (X being Cu, Co, Ni, Cr, Sn, Bi, Pb, and Sb) were weighed; all of these X metal precursors were chloride salts. Next, 1,2-hexadecanediol, the reducing agent, was weighed, with a molar ratio of reducing agent to metal precursor of 2.0.

[0046] Under a magnetic field strength of 2.0 T, a hydrogen-argon mixture of 93% Ar + 7% H2 was used as the protective atmosphere. The weighed reducing agent, metal precursor, and surfactants (perfluoropolyether ammonium hydroxylate and sodium polyacrylate) were added to a hydrogenated terphenyl solvent. The molar ratio of solvent to (metal precursor powder + reducing agent) was 40; the volume ratio of the two surfactants was 2:3; and the molar ratio of surfactant to solvent was 0.2. After thorough mixing, the solution was heated to 110°C at a heating rate of 5°C / min and held at this temperature for 45 min. Then, it was heated to 280°C at a rate of 4°C / min and held for 180 min before cooling to room temperature.

[0047] The obtained black mixed solution was then washed with the low-boiling-point solvent chloroform and collected by centrifugation. The volume ratio of the black mixed solution to the low-boiling-point solvent was 1:12. The centrifugation speed was 7000 r / min, and the centrifugation time was 8 min. After centrifugation, the supernatant was discarded, and the resulting precipitate was centrifuged five times. Finally, the obtained black precipitate was vacuum dried at 70℃ for 24 h to obtain a black powder, which is the FePt-based high-entropy alloy nanoparticle.

[0048] Field emission transmission electron microscopy (TEM) revealed that the particles were spherical, uniform in morphology, and well-dispersed; the average particle size was 14.66 nm. TEM-EDS characterization showed that all elements were uniformly distributed on the nanoparticles without elemental segregation. The catalytic performance of the product for the hydrogen evolution reaction was evaluated using an electrochemical workstation, showing an overpotential of 8.9 mV at 10 mA / cm². XRD measurements of the sample showed that the diffraction peak positions were significantly different from those of each element, and compared to… fcc The standard spectrum of the FePt phase (PDF#290718) is shifted 0.30° to the right, indicating that FePt-based high-entropy alloy nanoparticles were successfully synthesized.

[0049] Example 7: This embodiment describes a method for preparing FePt-based high-entropy alloy nanoparticles using a strong magnetic field-assisted wet chemical process, comprising the following steps: First, 0.3 mmol of ferric nitrate as the Fe metal precursor and 0.2 mmol of sodium chloroplatinate as the Pt metal precursor were weighed using an electronic balance. Then, 0.12 mmol of each of the five added element X metal precursors (X being Te, Ag, Au, Ru, and Pd) were weighed; all X metal precursors were nitrates. Next, dimethylacetamide, the reducing agent, was weighed, with a molar ratio of reducing agent to metal precursors of 1.5.

[0050] Under a magnetic field strength of 3.0 T, high-purity nitrogen was used as the protective atmosphere. The weighed reducing agent, metal precursor, and surfactants (oleylamine and oleamide) were added to a trioctylamine solvent. The molar ratio of solvent to (metal precursor powder + reducing agent) was 60; the volume ratio of the two surfactants was 3:2; and the molar ratio of surfactant to solvent was 0.3. After thorough mixing, the solution was heated to 120°C at a heating rate of 7°C / min and held at this temperature for 40 min. Then, it was heated to 300°C at a rate of 6°C / min and held for 150 min before cooling to room temperature.

[0051] The obtained black mixed solution was then washed with the low-boiling-point solvent n-hexane and collected by centrifugation. The volume ratio of the black mixed solution to the low-boiling-point solvent was 1:10. The centrifugation speed was 6000 r / min, and the centrifugation time was 5 min. After centrifugation, the supernatant was discarded, and the resulting precipitate was centrifuged four times. Finally, the obtained black precipitate was vacuum dried at 70℃ for 18 h to obtain a black powder, which is the FePt-based high-entropy alloy nanoparticle.

[0052] Field emission transmission electron microscopy (TEM) revealed that the particles were spherical, uniform in morphology, and well-dispersed; the average particle size was 3.83 nm. TEM-EDS characterization showed that all elements were uniformly distributed on the nanoparticles without elemental segregation. The catalytic performance of the product for the hydrogen evolution reaction was evaluated using an electrochemical workstation, showing an overpotential of 6.8 mV at 10 mA / cm². XRD measurements of the sample showed that the positions of the diffraction peaks were significantly different compared to those of the individual elements. fcc The standard spectrum of the FePt phase (PDF#290718) is shifted 0.26° to the right, indicating that FePt-based high-entropy alloy nanoparticles were successfully synthesized.

[0053] Example 8: This embodiment describes a method for preparing FePt-based high-entropy alloy nanoparticles using a strong magnetic field-assisted wet chemical process, comprising the following steps: First, 0.2 mmol of iron acetylacetone as the Fe metal precursor and 0.1 mmol of platinum acetylacetone as the Pt metal precursor were weighed using an electronic balance. Then, 0.03 mmol of each of the six added element metal precursors (X being Rh, Ir, Mo, La, Sm, and Ce) were weighed; all of these X metal precursors were acetylacetone salts. Next, sodium borohydride, the reducing agent, was weighed, with a molar ratio of reducing agent to metal precursors of 1.2.

[0054] Under a magnetic field strength of 1.5 T, a hydrogen-argon mixture of 93% Ar + 5% H2 was used as the protective atmosphere. The weighed reducing agent, metal precursor, and surfactants (oleylamine and oleamide) were added to a diphenyl ether solvent. The molar ratio of solvent to (metal precursor powder + reducing agent) was 30; the volume ratio of the two surfactants was 4:1; and the molar ratio of surfactant to solvent was 0.15. After thorough mixing, the solution was heated to 105 °C at a heating rate of 4 °C / min and held at this temperature for 50 min. Then, it was heated to 270 °C at a rate of 6 °C / min and held for 200 min before cooling to room temperature.

[0055] The obtained black mixed solution was then washed with the low-boiling-point solvent chloroform and collected by centrifugation. The volume ratio of the black mixed solution to the low-boiling-point solvent was 1:15. The centrifugation speed was 9000 r / min, and the centrifugation time was 8 min. After centrifugation, the supernatant was discarded, and the resulting precipitate was centrifuged five times. Finally, the obtained black precipitate was vacuum dried at 72℃ for 19 h to obtain a black powder, which is the FePt-based high-entropy alloy nanoparticle.

[0056] Field emission transmission electron microscopy (TEM) revealed that the particles were spherical, uniform in morphology, and well-dispersed; the average particle size was 5.12 nm. TEM-EDS characterization showed that all elements were uniformly distributed on the nanoparticles without elemental segregation. The catalytic performance of the product for the hydrogen evolution reaction was evaluated using an electrochemical workstation, showing an overpotential of 9.7 mV at 10 mA / cm². XRD measurements of the sample showed that the diffraction peak positions were significantly different from those of each element, and compared to… fcc The standard spectrum of the FePt phase (PDF#290718) is shifted 0.28° to the right, indicating that FePt-based high-entropy alloy nanoparticles were successfully synthesized.

[0057] Example 9: This embodiment describes a method for preparing FePt-based high-entropy alloy nanoparticles using a strong magnetic field-assisted wet chemical method, comprising the following steps: First, 0.4 mmol of ferric acetylacetone as the Fe metal precursor and 0.4 mmol of chloroplatinic acid as the Pt metal precursor were weighed using an electronic balance. Then, 0.18 mmol of each of the three added element metal precursors (X being Co, Ni, and Ru) were weighed; all X metal precursors were chloride salts. Next, ascorbic acid, the reducing agent, was weighed, with a molar ratio of reducing agent to metal precursors of 1.0.

[0058] Under a magnetic field strength of 4.0 T, a hydrogen-argon mixture of 93% Ar + 7% H2 was used as the protective atmosphere. The weighed reducing agent, metal precursor, and surfactants (perfluoropolyether ammonium hydroxyacid and oleic acid) were added to a trioctylamine solvent. The molar ratio of solvent to (metal precursor powder + reducing agent) was 70; the volume ratio of the two surfactants was 1:4; and the molar ratio of surfactant to solvent was 0.4. After thorough mixing, the solution was heated to 120°C at a heating rate of 8°C / min and held at this temperature for 30 min. Then, it was heated to 260°C at a rate of 10°C / min and held for 90 min before cooling to room temperature.

[0059] The obtained black mixed solution was then washed with the low-boiling-point solvent dimethyl ether and collected by centrifugation. The volume ratio of the black mixed solution to the low-boiling-point solvent was 1:17. The centrifugation speed was 10000 r / min, and the centrifugation time was 9 min. After centrifugation, the supernatant was discarded, and the resulting precipitate was centrifuged six times. Finally, the obtained black precipitate was vacuum dried at 78℃ for 22 h to obtain a black powder, which is the FePt-based high-entropy alloy nanoparticle.

[0060] Field emission transmission electron microscopy (TEM) revealed that the particles were spherical, uniform in morphology, and well-dispersed; the average particle size was 3.06 nm. TEM-EDS characterization showed that all elements were uniformly distributed on the nanoparticles without elemental segregation. The catalytic performance of the product for the hydrogen evolution reaction was evaluated using an electrochemical workstation, showing an overpotential of 18.9 mV at 10 mA / cm². XRD measurements of the sample showed that the diffraction peak positions were significantly different compared to the individual elements, and compared to… fcc The standard spectrum of the FePt phase (PDF#290718) is shifted 0.23° to the right, indicating that FePt-based high-entropy alloy nanoparticles were successfully synthesized.

[0061] Example 10: This embodiment describes a method for preparing FePt-based high-entropy alloy nanoparticles using a strong magnetic field-assisted wet chemical method, comprising the following steps: First, 0.6 mmol of ferric acetylacetone as the Fe metal precursor and 0.5 mmol of potassium chloroplatinate as the Pt metal precursor were weighed using an electronic balance. Then, 0.2 mmol of each of the six added element metal precursors (X being Cu, Mn, Co, Ni, Zn, and Pd) were weighed; all of these X metal precursors were acetylacetone salts. Next, hydrazine hydrate, the reducing agent, was weighed, with a molar ratio of reducing agent to metal precursors of 2.0.

[0062] Under a magnetic field strength of 4.0 T, high-purity argon was used as the protective atmosphere. The weighed reducing agent, metal precursor, and surfactants (perfluoropolyether ammonium hydroxyacid and oleic acid) were added to a hydrogenated terphenyl solvent. The molar ratio of solvent to (metal precursor powder + reducing agent) was 50; the volume ratio of the two surfactants was 5:1; and the molar ratio of surfactant to solvent was 0.25. After thorough mixing, the solution was heated to 110°C at a heating rate of 6°C / min and held at this temperature for 45 min. Then, it was heated to 290°C at a rate of 7°C / min and held for 120 min before cooling to room temperature.

[0063] The obtained black mixed solution was then washed with the low-boiling-point solvent chloroform and collected by centrifugation. The volume ratio of the black mixed solution to the low-boiling-point solvent was 1:16. The centrifugation speed was 8500 r / min, and the centrifugation time was 7 min. After centrifugation, the supernatant was discarded, and the resulting precipitate was centrifuged five times. Finally, the obtained black precipitate was vacuum dried at 74℃ for 18 h to obtain a black powder, which is the FePt-based high-entropy alloy nanoparticle.

[0064] Field emission transmission electron microscopy (TEM) revealed that the particles were spherical, uniform in morphology, and well-dispersed; the average particle size was 15.69 nm. TEM-EDS characterization showed that all elements were uniformly distributed on the nanoparticles without elemental segregation. The catalytic performance of the product for the hydrogen evolution reaction was evaluated using an electrochemical workstation, showing an overpotential of 26.4 mV at 10 mA / cm². XRD measurements of the sample showed that the positions of the diffraction peaks were significantly different compared to those of each element. fcc The standard spectrum of the FePt phase (PDF#290718) is shifted 0.26° to the right, indicating that FePt-based high-entropy alloy nanoparticles were successfully synthesized.

[0065] Example 11: This embodiment describes a method for preparing FePt-based high-entropy alloy nanoparticles using a strong magnetic field-assisted wet chemical method, comprising the following steps: First, 0.7 mmol of ferric acetylacetone as the Fe metal precursor and 0.7 mmol of sodium chloroplatinate as the Pt metal precursor were weighed using an electronic balance. Then, 0.25 mmol of each of the five added element metal precursors (X being Mn, Ni, Zn, Ag, and Ir) were weighed; all of these X metal precursors were chloride salts. Next, sodium citrate, the reducing agent, was weighed, with a molar ratio of reducing agent to metal precursor of 1.5.

[0066] Under a magnetic field strength of 5.0 T, a hydrogen-argon mixture of 93% Ar + 5% H2 was used as the protective atmosphere. The weighed reducing agent, metal precursor, and surfactants (polyetheretherketone and stearic acid) were added to a perfluoropolyether solvent. The molar ratio of solvent to (metal precursor powder + reducing agent) was 80; the volume ratio of the two surfactants was 2:5; and the molar ratio of surfactant to solvent was 0.5. After thorough mixing, the solution was heated to 118°C at a heating rate of 10°C / min and held at this temperature for 35 min. Then, it was heated to 340°C at a rate of 5°C / min and held for 70 min before cooling to room temperature.

[0067] The obtained black mixed solution was then washed with the low-boiling-point solvent cyclohexanone and collected by centrifugation. The volume ratio of the black mixed solution to the low-boiling-point solvent was 1:20. The centrifugation speed was 12000 r / min, and the centrifugation time was 10 min. After centrifugation, the supernatant was discarded, and the resulting precipitate was centrifuged six times. Finally, the obtained black precipitate was vacuum dried at 80℃ for 24 h to obtain a black powder, which is the FePt-based high-entropy alloy nanoparticle.

[0068] Field emission transmission electron microscopy (TEM) observation of the product revealed that the particles were spherical, uniform in morphology, and well-dispersed; the average particle size was 14.06 nm. TEM-EDS characterization showed that all elements were uniformly distributed on the nanoparticles without elemental segregation. The catalytic performance of the product for the hydrogen evolution reaction was evaluated using an electrochemical workstation, showing an overpotential of 28.9 mV at 10 mA / cm². XRD measurements of the sample showed that the positions of the diffraction peaks were significantly different compared to those of each element, and compared to… fcc The standard spectrum of the FePt phase (PDF#290718) is shifted 0.26° to the right, indicating that FePt-based high-entropy alloy nanoparticles were successfully synthesized.

[0069] Example 12: This embodiment describes a method for preparing FePt-based high-entropy alloy nanoparticles using a strong magnetic field-assisted wet chemical method, comprising the following steps: First, 0.8 mmol of ferric nitrate as the Fe metal precursor and 0.6 mmol of chloroplatinic acid as the Pt metal precursor were weighed using an electronic balance. Then, 0.3 mmol of each of the seven added element X metal precursors (X being Mn, Co, Ni, Zn, Ir, Ru, and Pd) were weighed; all X metal precursors were nitrates. Next, sodium hypophosphite, the reducing agent, was weighed, with a molar ratio of reducing agent to metal precursor of 1.2.

[0070] Under a magnetic field strength of 3.0 T, high-purity nitrogen was used as the protective atmosphere. The weighed reducing agent, metal precursor, and surfactants (oleylamine and oleamide) were added to a trioctylamine solvent. The molar ratio of solvent to (metal precursor powder + reducing agent) was 60; the volume ratio of the two surfactants was 3:2; and the molar ratio of surfactant to solvent was 0.3. After thorough mixing, the solution was heated to 120°C at a heating rate of 7°C / min and held at this temperature for 40 min. Then, it was heated to 300°C at a rate of 6°C / min and held for 150 min before cooling to room temperature.

[0071] The obtained black mixed solution was then washed with the low-boiling-point solvent cyclohexanone and collected by centrifugation. The volume ratio of the black mixed solution to the low-boiling-point solvent was 1:18. The centrifugation speed was 8000 r / min, and the centrifugation time was 7 min. After centrifugation, the supernatant was discarded, and the resulting precipitate was centrifuged five times. Finally, the obtained black precipitate was vacuum dried at 75℃ for 20 h to obtain a black powder, which is the FePt-based high-entropy alloy nanoparticle.

[0072] Field emission transmission electron microscopy (TEM) revealed that the particles were spherical, uniform in morphology, and well-dispersed; the average particle size was 4.19 nm. TEM-EDS characterization showed that all elements were uniformly distributed on the nanoparticles without elemental segregation. The catalytic performance of the product for the hydrogen evolution reaction was evaluated using an electrochemical workstation, showing an overpotential of 9.8 mV at 10 mA / cm². XRD measurements of the sample showed that the positions of the diffraction peaks were significantly different compared to those of each element. fcc The standard spectrum of the FePt phase (PDF#290718) is shifted 0.29° to the right, indicating that FePt-based high-entropy alloy nanoparticles were successfully synthesized.

[0073] Example 13: This embodiment describes a method for preparing FePt-based high-entropy alloy nanoparticles using a strong magnetic field-assisted wet chemical method, comprising the following steps: First, 0.6 mmol of ferric chloride as the Fe metal precursor and 0.8 mmol of potassium chloroplatinate as the Pt metal precursor were weighed using an electronic balance. Then, 0.2 mmol of each of the five added element X metal precursors (X being Co, Ni, Zn, Cr, and Rh) were weighed; all X metal precursors were chloride salts. Next, 1,2-hexadecanediol, the reducing agent, was weighed, with a molar ratio of reducing agent to metal precursor of 1.3.

[0074] Under a magnetic field strength of 1.2 T, a hydrogen-argon mixture of 93% Ar + 7% H2 was used as the protective atmosphere. The weighed reducing agent, metal precursor, and surfactants (polyvinylpyrrolidone and sodium polyacrylate) were added to a diphenyl ether solvent. The molar ratio of solvent to (metal precursor powder + reducing agent) was 25; the volume ratio of the two surfactants was 3:2; and the molar ratio of surfactant to solvent was 0.2. After thorough mixing, the solution was heated to 108℃ at a heating rate of 4℃ / min and held at this temperature for 55 min. Then, it was heated to 260℃ at a rate of 6℃ / min and held for 160 min before cooling to room temperature.

[0075] The obtained black mixed solution was then washed with the low-boiling-point solvent ethanol and collected by centrifugation. The volume ratio of the black mixed solution to the low-boiling-point solvent was 1:5. The centrifugation speed was 6000 r / min and the centrifugation time was 5 min. After centrifugation, the supernatant was discarded, and the resulting precipitate was centrifuged three times. Finally, the obtained black precipitate was vacuum dried at 60℃ for 12 h to obtain a black powder, which is the FePt-based high-entropy alloy nanoparticle.

[0076] Field emission transmission electron microscopy (TEM) revealed that the particles were spherical, uniform in morphology, and well-dispersed; the average particle size was 20.0 nm. TEM-EDS characterization showed that all elements were uniformly distributed on the nanoparticles without elemental segregation. The catalytic performance of the product for the hydrogen evolution reaction was evaluated using an electrochemical workstation, revealing an overpotential of 40.0 mV at 10 mA / cm². XRD measurements of the sample showed significantly different diffraction peak positions compared to the individual elements, and compared to… fcc The standard spectrum of the FePt phase (PDF#290718) is shifted 0.28° to the right, indicating that FePt-based high-entropy alloy nanoparticles were successfully synthesized.

[0077] Example 14: This embodiment describes a method for preparing FePt-based high-entropy alloy nanoparticles using a strong magnetic field-assisted wet chemical method, comprising the following steps: First, 0.5 mmol of iron acetylacetone as the Fe metal precursor and 0.6 mmol of platinum acetylacetone as the Pt metal precursor were weighed using an electronic balance. Then, 0.2 mmol of each of the ten additive element X metal precursors (X being Cu, Mn, Co, Ni, Zn, Sn, Ru, Pd, Rh, and Ir) were weighed; all X metal precursors were acetylacetone salts. Next, the reducing agent dimethylacetamide was weighed, with a molar ratio of reducing agent to metal precursors of 1.7.

[0078] Under a magnetic field strength of 2.0 T, a hydrogen-argon mixture of 93% Ar + 7% H2 was used as the protective atmosphere. The weighed reducing agent, metal precursor, and surfactants (perfluoropolyether ammonium hydroxylate and sodium polyacrylate) were added to a hexadecylamine solvent. The molar ratio of solvent to (metal precursor powder + reducing agent) was 45; the volume ratio of the two surfactants was 2:3; and the molar ratio of surfactant to solvent was 0.2. After thorough mixing, the solution was heated to 110°C at a heating rate of 5°C / min and held at this temperature for 45 min. Then, it was heated to 280°C at a rate of 4°C / min and held for 180 min before cooling to room temperature.

[0079] The obtained black mixed solution was then washed with the low-boiling-point solvent n-hexane and collected by centrifugation. The volume ratio of the black mixed solution to the low-boiling-point solvent was 1:10. The centrifugation speed was 8000 r / min, and the centrifugation time was 8 min. After centrifugation, the supernatant was discarded, and the resulting precipitate was centrifuged five times. Finally, the obtained black precipitate was vacuum dried at 70℃ for 16 h to obtain a black powder, which is the FePt-based high-entropy alloy nanoparticle.

[0080] Field emission transmission electron microscopy (TEM) revealed that the particles were spherical, uniform in morphology, and well-dispersed; the average particle size was 8.72 nm. TEM-EDS characterization showed that all elements were uniformly distributed on the nanoparticles without elemental segregation. The catalytic performance of the product for the hydrogen evolution reaction was evaluated using an electrochemical workstation, showing an overpotential of 17.6 mV at 10 mA / cm². XRD measurements of the sample showed that the diffraction peak positions were significantly different from those of each element, and compared to… fcc The standard spectrum of the FePt phase (PDF#290718) is shifted 0.33° to the right, indicating that FePt-based high-entropy alloy nanoparticles were successfully synthesized.

[0081] Example 15: This embodiment describes a method for preparing FePt-based high-entropy alloy nanoparticles using a strong magnetic field-assisted wet chemical method, comprising the following steps: First, 0.5 mmol of ferric chloride as the Fe metal precursor and 0.4 mmol of chloroplatinic acid as the Pt metal precursor were weighed using an electronic balance. Then, 0.2 mmol of each of the three added element X metal precursors (X being Co, Ni, and Ru) were weighed; all X metal precursors were chloride salts. Next, 1,2-hexadecanediol, the reducing agent, was weighed, with a molar ratio of reducing agent to metal precursors of 1.0.

[0082] Under a magnetic field strength of 6.0 T, a hydrogen-argon mixture of 93% Ar + 5% H2 was used as the protective atmosphere. The weighed reducing agent, metal precursor, and surfactants (oleylamine and oleic acid) were added to a hexadecylamine solvent. The molar ratio of solvent to (metal precursor powder + reducing agent) was 50; the volume ratio of the two surfactants was 10:10; and the molar ratio of surfactant to solvent was 0.3. After thorough mixing, the solution was heated to 105℃ at a heating rate of 5℃ / min and held at this temperature for 60 min. Then, it was heated to 360℃ at a rate of 6℃ / min and held for 210 min before cooling to room temperature.

[0083] The obtained black mixed solution was then washed with the low-boiling-point solvent petroleum ether and collected by centrifugation. The volume ratio of the black mixed solution to the low-boiling-point solvent was 1:8. The centrifugation speed was 7000 r / min, and the centrifugation time was 5 min. After centrifugation, the supernatant was discarded, and the resulting precipitate was centrifuged three times. Finally, the obtained black precipitate was vacuum dried at 60℃ for 12 h to obtain a black powder, which is the FePt-based high-entropy alloy nanoparticle.

[0084] Field emission transmission electron microscopy (TEM) observation of the product revealed that the particles were spherical, uniform in morphology, and well-dispersed; the average particle size was 3.98 nm. TEM-EDS characterization showed that all elements were uniformly distributed on the nanoparticles without elemental segregation. The catalytic performance of the product for the hydrogen evolution reaction was evaluated using an electrochemical workstation, showing an overpotential of 15.8 mV at 10 mA / cm². XRD measurements of the sample showed that the positions of the diffraction peaks were significantly different compared to those of each element, and compared to… fcc The standard spectrum of the FePt phase (PDF#290718) is shifted 0.24° to the right, indicating that FePt-based high-entropy alloy nanoparticles were successfully synthesized.

[0085] Example 16: This embodiment describes a method for preparing FePt-based high-entropy alloy nanoparticles using a strong magnetic field-assisted wet chemical method, comprising the following steps: First, 0.6 mmol of iron acetylacetone as the Fe metal precursor and 0.8 mmol of platinum acetylacetone as the Pt metal precursor were weighed using an electronic balance. Then, 0.2 mmol of each of the five added element metal precursors (X being Co, Cu, and Ni) were weighed; all of these X metal precursors were acetylacetone salts. Next, 1,2-hexadecanediol, the reducing agent, was weighed, with a molar ratio of reducing agent to metal precursor of 1.2.

[0086] Under a magnetic field strength of 2.0 T, a hydrogen-argon mixture of 93% Ar + 7% H2 was used as the protective atmosphere. The weighed reducing agent, metal precursor, and surfactants (oleylamine and oleic acid) were added to an octadecylamine solvent. The molar ratio of solvent to (metal precursor powder + reducing agent) was 20; the volume ratio of the two surfactants was 10:5; and the molar ratio of surfactant to solvent was 0.4. After thorough mixing, the solution was heated to 110℃ at a heating rate of 5℃ / min and held at this temperature for 90 min. Then, it was heated to 340℃ at a rate of 5℃ / min and held for 240 min before cooling to room temperature.

[0087] The obtained black mixed solution was then washed with the low-boiling-point solvent ethanol and collected by centrifugation. The volume ratio of the black mixed solution to the low-boiling-point solvent was 1:7. The centrifugation speed was 8000 r / min, and the centrifugation time was 6 min. After centrifugation, the supernatant was discarded, and the resulting precipitate was centrifuged four times. Finally, the obtained black precipitate was vacuum dried at 80℃ for 17 h to obtain a black powder, which is the FePt-based high-entropy alloy nanoparticle.

[0088] Field emission transmission electron microscopy (TEM) observation of the product revealed that the particles were spherical, uniform in morphology, and well-dispersed; the average particle size was 8.19 nm. TEM-EDS characterization showed that all elements were uniformly distributed on the nanoparticles without elemental segregation. The catalytic performance of the product for the hydrogen evolution reaction was evaluated using an electrochemical workstation, showing an overpotential of 20.5 mV at 10 mA / cm². XRD measurements of the sample showed that the positions of the diffraction peaks were significantly different compared to those of each element, and compared to… fcc The standard spectrum of the FePt phase (PDF#290718) is shifted 0.25° to the right, indicating that FePt-based high-entropy alloy nanoparticles were successfully synthesized.

[0089] As can be seen from the above embodiments, the FePt-based high-entropy alloy nanoparticles synthesized by the strong magnetic field-assisted wet chemical method of the present invention exhibit excellent catalytic performance of hydrogen evolution reaction, and the high-entropy alloy nanoparticles have uniform morphology, good dispersibility, uniform composition, and small particle size.

Claims

1. A method for preparing FePt-based high-entropy alloy nanoparticles using a strong magnetic field-assisted wet chemical process, characterized in that, Includes the following steps: Step (1): Mole ratio Fe : Pt : X1 : X2 : … : X n = (0.1~1.0) : (0.1~1.0) : (0.03~0.3) : (0.03~0.3) : … : (0.03~0.3) (3 ≤ n ≤ 10) Weigh Fe, Pt and X metal precursors, where X is an added element; then weigh the reducing agent according to a molar ratio of reducing agent to metal precursor of 1.0~2.0; Step (2): Mix the weighed reducing agent and metal precursor with the solvent, then add the surfactant, and prepare a black mixed solution by heating in two stages under a strong magnetic field of 1.0~6.0T and an inert atmosphere: first heat to 100~120℃ at a heating rate of 3~10℃ / min and hold for 30~60 min, then heat to 260~360℃ at a heating rate of 3~10℃ / min and hold for 60~300 min before cooling to room temperature; Step (3): The obtained black mixed solution is washed with a low-boiling-point solvent and collected by centrifugation at a speed of 2000~12000 r / min for 3~10 min. After centrifugation, the upper layer of centrifuged liquid is discarded, and the obtained precipitate is centrifuged 3~6 times. Finally, the obtained black precipitate is vacuum dried at 60~80℃ for 12~24 h to obtain black powder, which is FePt-based high-entropy alloy nanoparticles with an average particle size of 2.0~20.0 nm and all phases are FePt phase. In step (1), the Fe metal precursor is selected from one of ferric acetylacetone, ferric sulfate, ferric acetate, or ferric nitrate; the Pt metal precursor is selected from one of platinum acetylacetone, chloroplatinic acid, or potassium chloroplatinate; the X metal precursor is selected from one of the salts of acetylacetone, chloride, sulfate, or nitrate, and the corresponding X element is 3 to 10 of the elements Cu, Mn, Co, Ni, Zn, Cr, Sn, Bi, Pb, Sb, Te, Ag, Ru, Rh, Ir, Mo, La, Sm, and Ce. In step (1), the reducing agent is selected from one of hydrazine hydrate, sodium citrate, sodium hypophosphite, 1,2-hexadecanediol, and dimethylacetamide; In step (2), the solvent is selected from one of diphenyl ether, hydrogenated terphenyl, perfluoropolyether, hexadecylamine, octadecylamine, and trioctylamine, and the molar ratio of the solvent to the metal precursor powder + reducing agent is (20~80): 1, with the unit being mmol: mmol; The FePt-based high-entropy alloy nanoparticles obtained in step (3) exhibit excellent performance in the electrocatalytic hydrogen evolution reaction, with an overpotential of 5~40 mV at 10 mA / cm².

2. The method for preparing FePt-based high-entropy alloy nanoparticles by a strong magnetic field-assisted wet chemical method according to claim 1, characterized in that, In step (2), the surfactant is selected from two of the following: polyether ether ketone, perfluoropolyether ammonium hydroxide, polyvinylpyrrolidone, sodium polyacrylate, oleylamine, oleic acid, stearic acid, and oleamide. The volume ratio of the two surfactants is (1~10):(1~10); and the molar ratio of surfactant to solvent is (0.1~0.5):1.0, with units of mmol:mmol.

3. The method for preparing FePt-based high-entropy alloy nanoparticles by a strong magnetic field-assisted wet chemical method according to claim 1, characterized in that, The inert atmosphere in step (2) is selected from one of the following atmospheres: 95%Ar + 5%H2, 93%Ar + 7%H2, high-purity nitrogen or high-purity argon.

4. The method for preparing FePt-based high-entropy alloy nanoparticles by a strong magnetic field-assisted wet chemical method according to claim 1, characterized in that, In step (3), the low-boiling-point solvent is selected from one of n-hexane, petroleum ether, chloroform, ethanol, methyl ether, and cyclohexanone, and the volume ratio of the black mixed solution to the low-boiling-point solvent during cleaning is 1: (2~20).

5. The method for preparing FePt-based high-entropy alloy nanoparticles by a strong magnetic field-assisted wet chemical method according to claim 1, characterized in that, The morphology and elemental distribution of the FePt-based high-entropy alloy nanoparticles obtained in step (3) were characterized by field emission transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS); the phase composition was confirmed by X-ray diffraction (XRD); and the electrocatalytic hydrogen evolution performance was evaluated using an electrochemical workstation.

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