A method for preparing a carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macroscopic body

Abstract

This invention relates to the field of controllable preparation of carbon nanotube composite macrostructures, specifically a method for preparing carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructures. The method uses high-quality carbon nanotube macrostructures as a carrier, employing a wet chemical method to grow ultrafine high-entropy alloy nanowires on a carbon nanotube network. Rapid heating carbonizes the surfactants adsorbed on the ultrafine nanowires to form a nitrogen-doped graphite carbon layer. This carbon layer connects the nanowires and carbon nanotube bundles to form an integrated composite macrostructure. During the preparation of the ultrafine high-entropy alloy nanowires, the composition, morphology, carbon layer thickness, crystallinity, and nitrogen doping amount of the ultrafine high-entropy nanowires are controlled by altering the wet chemical synthesis conditions and heat treatment processes. The prepared carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructure can be directly used as a hydrogen evolution electrode in water electrolysis, exhibiting both high activity and high stability, and is expected to find applications in hydrogen production through water electrolysis.

Description

Technical Field

[0001] This invention relates to the field of controllable preparation of carbon nanotube composite macrostructures, specifically a method for preparing carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructures. Background Technology

[0002] Nanowires, as a typical one-dimensional material, exhibit excellent physicochemical properties due to their structural characteristics such as tunable radial dimensions and high specific surface area. Ultrafine metallic nanowires, in particular, have attracted widespread attention from researchers since their synthesis. In recent years, researchers have synthesized ultrafine high-entropy alloy nanowires composed of five or more metals. These ultrafine high-entropy alloy nanowires possess characteristics such as multi-component composition, abundant unsaturated coordination, and tunable d-band centers, showing broad application prospects in optoelectronic devices, energy storage and conversion, and catalysis.

[0003] To explore the application of ultrafine high-entropy alloy nanowires in energy storage and conversion, Huang et al. prepared PtRuNiCoFeMo high-entropy alloy nanowires using a wet chemical method, which exhibited excellent electrocatalytic hydrogenation performance. This was mainly due to the strong interaction between different metals in the high-entropy nanowires, which could regulate the electronic structure between different metals (Reference 1: Nat. Commun. 12, 6261 (2021)). Wang et al. designed an ultrafine high-entropy alloy nanowire with the composition PtRuRhCoNi. Due to the complementary effect of the electronic structures of different metals, its activity for binding intermediates in redox reactions was maximized. Therefore, this nanowire showed excellent activity and durability in the electrocatalytic oxidation of ethanol / methanol and hydrogen evolution reactions in acidic and alkaline solutions (Reference 2: Appl. Catal. B: Environ. 312 (2022) 121431). et al. further optimized the composition of high-entropy alloys and synthesized PtNiGaSnMoRe high-entropy alloy nanowires, which have structural characteristics such as more metallic elements and ultra-fine radial dimensions. Their surface contains a large number of unsaturated coordination sites and oxyphilic elements, which can reduce the binding of CO intermediates (CO*) and enhance the adsorption of hydroxyl groups (-OH), thereby lowering the energy barrier for the conversion of CO* to carboxyl groups (-COOH), demonstrating excellent electrocatalytic methanol oxidation performance and resistance to CO poisoning (Reference 3: Adv. Energy Mater. 2023, 2301408). Current research on ultrafine high-entropy alloy nanowires mainly focuses on composition control. Wet chemical methods are used to grow ultrafine high-entropy alloy nanowires using surfactants as templates, and then naphthol is used as a binder to support them on conductive carriers for electrocatalytic reactions.

[0004] In summary, ultrafine high-entropy alloy nanowires with different compositions have shown excellent activity and promising application prospects in the field of electrocatalysis, but their stability urgently needs to be improved, and there is still room for further improvement in their activity. This is mainly because there are still some problems with ultrafine high-entropy alloy nanowires synthesized by wet chemical method: (1) Non-noble metal elements in ultrafine high-entropy alloy nanowires are easily soluble in acidic electrolytes, resulting in poor compositional stability. (2) Nanowires dispersed in solution need to be supported on conductive carriers, which are prone to detachment during electrochemical reactions, leading to catalyst deactivation. (3) The surface of nanowires is coated with surfactants and polymers such as oleylamine, which affects the exposure of their active sites during catalytic reactions and reduces catalytic activity. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructures. Surfactants and oleylamine are adsorbed on the surface of the high-entropy alloy nanowires, and the surface organic matter is rapidly thermally treated in an inert atmosphere to form a nitrogen-doped carbon layer. This method solves the problems of poor compositional stability and low catalyst activity of ultrafine high-entropy alloy nanowires in the prior art, and makes it have both high activity and high stability when used as an electrocatalyst.

[0006] The technical solution of the present invention:

[0007] A method for preparing carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructures involves wet-growing ultrafine high-entropy alloy nanowires using different metal acetylacetone salts as precursors and surfactants as templates on a high-quality self-supporting carbon nanotube macrostructure network. Rapid heating is used to carbonize the surfactants, forming a nitrogen-doped carbon layer uniformly coating the surface of the ultrafine high-entropy alloy nanowires. This nitrogen-doped carbon layer connects the ultrafine high-entropy alloy nanowires and carbon nanotube bundles to form an integrated composite macrostructure. The composition and size of the ultrafine high-entropy alloy nanowires are controlled by altering the type of precursor source, heating temperature, and time during synthesis. The thickness, crystallinity, and nitrogen doping amount of the coating carbon layer are controlled by adjusting the composition and amount of the surfactant and the rapid heating temperature.

[0008] The method for preparing carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructures uses high-quality self-supporting carbon nanotube macrostructures composed of networks of single-walled carbon nanotubes, double-walled carbon nanotubes, or few-walled carbon nanotubes. The macrostructures are thin films, fibers, or sponges. These macrostructures have the characteristics of high conductivity, self-support, and adjustable size.

[0009] The method for preparing the carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructure directly utilizes the surfactant and oleylamine solvent adsorbed on the surface of the ultrafine high-entropy alloy nanowire during the wet synthesis process. The nanowire is then rapidly heated in an inert atmosphere to form a nitrogen-doped carbon layer, which coats the ultrafine high-entropy alloy nanowire and simultaneously connects with the carbon nanotube bundle to form an integrated composite macrostructure.

[0010] The method for preparing carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructures controls the thickness, crystallinity, and nitrogen doping amount of the coated carbon layer by changing the type and concentration of surfactants in the wet synthesis process and the temperature and time of rapid thermal treatment.

[0011] The method for preparing carbon-coated ultrafine high-entropy alloy nanowires / carbon nanotube composite macrostructures describes that the ultrafine high-entropy alloy nanowires have adjustable composition and size. The composition of the ultrafine high-entropy alloy nanowires can be controlled by changing the type and ratio of the metal precursor source during the growth of the ultrafine high-entropy alloy nanowires, and the diameter and length of the ultrafine high-entropy alloy nanowires can be controlled by changing the heating temperature and time, and the type and concentration of the surfactant.

[0012] The method for preparing carbon-coated ultrafine high-entropy alloy nanowires / carbon nanotube composite macrostructures uses transition metals or noble metals in the prepared ultrafine high-entropy alloy nanowires.

[0013] The method for preparing carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructures uses transition metals such as Fe, Co, Ni, Cu, Mo, W, Re, and Ta, and noble metals such as Au, Ag, Pt, Pd, Ru, Rh, and Ir, with a total of 5 or more metal types.

[0014] The method for preparing the carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructure allows for adjustable length and diameter of the ultrafine high-entropy alloy nanowires within the ranges of 10–500 nm and 2.0–5.0 nm, respectively. For different size requirements of the ultrafine high-entropy alloy nanowires, the oil bath heating temperature range is 100–300 °C, and the heating time is 2–120 min. The rapid heating carbonization temperature range is 600–1200 °C, and the heating time is 5–60 s.

[0015] The method for preparing carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructures describes a method for preparing composite macrostructures that can be directly used as electrocatalytic hydrogen evolution electrodes. The nitrogen-doped carbon layer in these composite macrostructures simultaneously enhances catalytic activity and stability, enabling hydrogen evolution reactions to proceed under acidic conditions at a current density of 10 A / cm². 2 The overpotential is only 20mV, and it operates stably for 200 hours without decay.

[0016] The method for preparing carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructures is described above. These composite macrostructures are widely used in the fields of energy storage and conversion, including electrocatalytic hydrogen evolution, electrocatalytic carbon dioxide reduction, and electrocatalytic ammonia synthesis.

[0017] The design concept of this invention is:

[0018] This invention disperses a carbon nanotube network in oleylamine containing a metal precursor salt and a surfactant to obtain high-entropy alloy nanowires on the surface of the surfactant and oleylamine. Under an inert atmosphere, the polymer adsorbed on the surface of the wet-synthesized nanowires is pyrolyzed and carbonized by rapid heating to form a loose and porous nitrogen-doped carbon layer. This nitrogen-doped carbon layer connects the high-entropy alloy nanowires and the carbon nanotube network, forming an integrated carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructure. The nitrogen-doped carbon layer not only enhances the bonding force between the nanowires and the carbon nanotube carrier, but also prevents the transition metal in the active component from dissolving in the acidic electrolyte, while improving the activity and stability of the composite macrostructure as an electrocatalyst.

[0019] In addition, during the preparation of ultrafine high-entropy alloy nanowires, the composition, length, and diameter of the ultrafine high-entropy alloy nanowires can be controlled by changing the type and concentration of the metal precursor salt, the heating time, and the temperature; the thickness, crystallinity, and nitrogen doping amount of the nitrogen-doped carbon layer can be controlled by changing the composition and amount of the surfactant and the rapid thermal treatment temperature and time.

[0020] The advantages and beneficial effects of this invention are:

[0021] 1. This invention provides a simple and controllable method for preparing a nitrogen-doped carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructure. The method involves growing ultrafine high-entropy alloy nanowires in situ on the surface of carbon nanotubes and using rapid heating to pyrolyze surfactant molecules to form a nitrogen-doped carbon layer, thereby connecting the ultrafine high-entropy alloy nanowires to the carbon nanotubes.

[0022] 2. This invention directly carbonizes the high-molecular organic matter that hinders the exposure of high-entropy alloy nanowires into a nitrogen-doped carbon layer. The nitrogen doping can effectively improve the wettability with the electrolyte, enhance the bonding between the support and the metal catalyst, and improve the stability of the catalyst.

[0023] 3. The method of this invention uses a single-walled carbon nanotube network with a large specific surface area and high conductivity as a support. The nitrogen-doped carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructure prepared can be directly used as an electrocatalytic hydrogen evolution electrode and has industrial application prospects. Attached Figure Description

[0024] Figure 1 A schematic diagram of the process for preparing carbon-coated ultrafine high-entropy alloy nanowire / single-walled carbon nanotube composite macrostructures.

[0025] In the figure, SWCNT is a single-walled carbon nanotube, HEAN / SWCNT is a high-entropy alloy nanowire / single-walled carbon nanotube composite film, and HEAN@NC / SWCNT is an N-doped carbon layer coated high-entropy alloy nanowire / single-walled carbon nanotube composite film.

[0026] Figure 2 Transmission electron microscopy (TEM) image of carbon-coated ultrafine high-entropy alloy nanowire / single-walled carbon nanotube composite film.

[0027] Figure 3(a). X-ray photoelectron spectroscopy of carbon-coated ultrafine high-entropy alloy nanowire / single-walled carbon nanotube composite film.

[0028] Figure 3(b). X-ray photoelectron spectroscopy of nitrogen in carbon-coated ultrafine high-entropy alloy nanowire / single-walled carbon nanotube composite films.

[0029] Figure 4 Inductively coupled plasma atomic emission spectra of carbon-coated ultrafine high-entropy alloy nanowire / single-walled carbon nanotube composite films.

[0030] Figure 5 Linear voltammetric curves of electrocatalytic hydrogen evolution of carbon-coated ultrafine high-entropy alloy nanowire / single-walled carbon nanotube composite films.

[0031] Figure 6 Electrocatalytic hydrogen evolution stability test of carbon-coated ultrafine high-entropy alloy nanowire / single-walled carbon nanotube composite films.

[0032] Figure 7 Transmission electron microscopy (TEM) image of an ultrafine high-entropy alloy nanowire / single-walled carbon nanotube composite film.

[0033] Figure 8 Linear voltammetric curves of electrocatalytic hydrogen evolution of ultrafine high-entropy alloy nanowire / single-walled carbon nanotube composite films.

[0034] Figure 9 Electrocatalytic hydrogen evolution stability test of ultrafine high-entropy alloy nanowire / single-walled carbon nanotube composite films. Detailed Implementation

[0035] In its specific implementation, this invention proposes a method for preparing a carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructure. Using a high-quality carbon nanotube macrostructure as a carrier, ultrafine high-entropy alloy nanowires are grown on a carbon nanotube network using a wet chemical method. The carbon nanotube network is dispersed in oleylamine containing dissolved acetylacetone metal salt and surfactant to obtain ultrafine high-entropy nanowires coated with a high-molecular-weight organic compound. Under an inert atmosphere, rapid heating is used to carbonize the surfactant adsorbed on the ultrafine nanowires, forming a nitrogen-doped graphite carbon layer. Heat treatment yields the nitrogen-doped carbon layer-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructure. The nanowires are connected to the carbon nanotube bundle through the nitrogen-doped graphite carbon layer. Furthermore, by changing the wet chemical synthesis conditions and heat treatment process parameters, the composition, morphology, carbon layer thickness, carbon layer crystallinity, and nitrogen doping amount of the ultrafine high-entropy nanowires can be controlled, allowing the macrostructure to be directly used as an electrocatalytic electrode, while simultaneously testing its activity and stability.

[0036] The present invention will now be further described in detail through examples.

[0037] Example 1

[0038] like Figure 1 As shown, the preparation of carbon-coated PtFeCoNiCu ultrafine high-entropy alloy nanowire / single-walled carbon nanotube composite films is carried out through the following experimental steps:

[0039] (1) Synthesis of ultrafine high-entropy alloy nanowires

[0040] Hexadecyltrimethylammonium bromide was placed in oleylamine solvent and ultrasonically treated for 10 min to achieve uniform dispersion. Then, acetylacetone salt M was added. x (acac) y A mixture of metals (M = Pt, Fe, Co, Ni, Cu) was dispersed in a solution, and a single-walled carbon nanotube network was added simultaneously. The solution was then sonicated in a constant-temperature water bath for 2 hours to ensure complete dissolution of the metal salts and complete dispersion of the carbon nanotubes. The mixed solution was then heated in an oil bath at 200°C for 20 minutes to obtain ultrafine high-entropy alloy nanowires / single-walled carbon nanotubes. The length and diameter of the ultrafine high-entropy alloy nanowires were 5–20 nm and 2–3 nm, respectively.

[0041] (2) Rapid thermal carbonization forms a carbon coating layer

[0042] The composite structure obtained in step (1) was dried in a 60°C forced-air drying oven, and then placed on a graphite plate and heated to 800°C within 10 seconds to obtain a carbon-coated ultrafine high-entropy alloy nanowire / single-wall carbon nanotube composite film.

[0043] (3) Structural and compositional characterization of complex macrostructures

[0044] The composite film obtained in step (2) was ultrasonically dispersed in ethanol and then dropped onto a copper mesh microgrid. Its microstructure was observed using a transmission electron microscope as follows: Figure 2 As shown, a carbon layer is uniformly coated on ultrafine nanowires, while simultaneously connecting the nanowires to carbon nanotube bundles.

[0045] The composition of the composite thin film was analyzed using X-ray photoelectron spectroscopy and inductively coupled plasma atomic emission spectroscopy, as shown in Figures 3(a)-(b). Figure 4 As shown, the results indicate that Pt, Fe, Co, Ni, and Cu elements are present in the composite film, with an atomic ratio of Pt:Fe:Co:Ni:Cu = 17:19:13:32:19. Nitrogen elements exhibit pyrrole, pyridine, and graphitic forms, demonstrating the presence of N-doped carbon-coated high-entropy alloy nanowires.

[0046] (4) Electrocatalytic hydrogen evolution performance test of the composite macrostructure

[0047] In a three-electrode electrochemical workstation, a composite thin film (counter electrode: graphite electrode; reference electrode: Ag / AgCl electrode; electrolyte solution: 0.5 mol / L H₂SO₄ aqueous solution) was held by electrode clips, and linear voltammetry curves were measured at a scan rate of 5 mV / s. Figure 5 As shown, the test results indicate that at 10 mA / cm 2 The overpotential at the given current density is only 20 mV, indicating that the composite film possesses excellent electrocatalytic hydrogen evolution activity.

[0048] At a constant potential of 20mV (10mA / cm) 2 The test was conducted under overpotential at current density, and the test results are as follows: Figure 6 As shown, the results indicate that the current density did not decrease after 200 hours of testing. This demonstrates that the composite film exhibits excellent electrocatalytic hydrogen evolution stability.

[0049] Example 2

[0050] In this embodiment, the carbon-coated PtFeCoNiMo ultrafine high-entropy alloy nanowire / double-walled carbon nanotube composite sponge is described in the following experimental steps:

[0051] (1) Synthesis of ultrafine high-entropy alloy nanowires

[0052] Same as step (1) in Example 1, except that: the composition M of acetylacetone salt is adjusted. x (acac) y(M = Pt, Fe, Co, Ni, Mo), with didecyldimethylammonium bromide as the surfactant, a double-walled carbon nanotube network was placed in a mixed solution and heated in an oil bath at 150°C for 100 min to obtain ultrafine high-entropy alloy nanowires / double-walled carbon nanotubes. The length and diameter of the ultrafine high-entropy alloy nanowires were 5–15 nm and 1–2 nm, respectively.

[0053] (2) Preparation of carbon coating layer by heating carbonization

[0054] Ultrafine high-entropy alloy nanowires / double-walled carbon nanotubes were carbonized and then ultrasonically dispersed for 30 min to ensure thorough dispersion in deionized water. The mixed solution was freeze-dried for 24 h and then heat-treated to 600 °C within 10 s to obtain a carbon-coated ultrafine high-entropy alloy nanowire / double-walled carbon nanotube composite sponge.

[0055] (3) Structural representation of macroscopic bodies

[0056] Same as step (3) in Example 1.

[0057] (4) Performance testing of macroscopic bodies

[0058] Following step (4) of Example 1, the performance of the carbon-coated ultrafine high-entropy alloy nanowire / double-walled carbon nanotube composite sponge was tested. The test results showed that at 10 mA / cm², the performance was satisfactory. 2 The overpotential at the current density is only 38mV, and there is no decay of the current density after 240h of testing, indicating that the composite sponge has excellent electrocatalytic hydrogen evolution activity and stability.

[0059] Example 3

[0060] In this embodiment, carbon-coated PtFeCoNiRu ultrafine high-entropy alloy nanowires / few-walled carbon nanotube composite fibers were used. The specific experimental steps were as follows:

[0061] (1) Synthesis of ultrafine high-entropy alloy nanowires

[0062] Same as step (1) in Example 1, except that: the composition M of acetylacetone salt is adjusted. x (acac) y (M = Pt, Fe, Co, Ni, Ru) The few-walled carbon nanotubes were dispersed in a mixed solution and heated in an oil bath at 280℃ for 10 min to obtain ultrafine high-entropy alloy nanowires / few-walled carbon nanotubes. The length and diameter of the ultrafine high-entropy alloy nanowires were 5-30 nm and 2-4 nm, respectively.

[0063] (2) Preparation of carbon coating layer by heating carbonization

[0064] The composite fiber was obtained by wet spinning of the low-walled carbon nanotubes carrying ultrafine nanowires, and then carbonized as in step (2) of Example 1. The fiber was then heated to 1150°C within 10 seconds to obtain carbon-coated ultrafine high-entropy alloy nanowire / low-walled carbon nanotube composite fiber.

[0065] (3) Structural representation of macroscopic bodies

[0066] Same as step (3) in Example 1.

[0067] (4) Performance testing of macroscopic bodies

[0068] Following step (4) of Example 1, the performance of the carbon-coated ultrafine high-entropy alloy nanowire / double-walled carbon nanotube composite sponge was tested. The test results showed that at 10 mA / cm², the performance was satisfactory. 2 The overpotential at the current density is only 42mV, and there is no decay of the current density after 188h, indicating that the composite fiber has excellent hydrogen evolution activity and stability.

[0069] Comparative Example 1

[0070] In this comparative example, the preparation of PtFeCoNiCu ultrafine high-entropy alloy nanowires / single-walled carbon nanotube composite films was carried out through the following specific steps:

[0071] (1) Same as step (1) in Example 1, except that: ethanol is used to clean the single-walled carbon nanotube film loaded with ultrafine high-entropy nanowires to remove residual surfactants and polymers such as oleylamine from the surface of the nanowires.

[0072] (2) Same as step (3) in Example 1, its microstructure is as follows Figure 7 As shown, no carbon layer was found on the surface of the ultrafine high-entropy alloy nanowires.

[0073] (3) Same as step (4) in Example 1, as follows Figure 8 and Figure 9 As shown, the test results indicate that at 10 mA / cm 2 The overpotential at the current density was 68mV. During the 24-hour hydrogen evolution performance test, the current density decreased significantly, indicating that the composite film had poor catalytic activity and stability.

[0074] The results of the examples and comparative examples show that the ultrafine high-entropy alloy nanowire / carbon nanotube composite film coated with a nitrogen-doped carbon layer exhibits both higher activity and stability in the electrocatalytic hydrogen evolution reaction. The most significant feature of this invention compared to existing technologies is that the organic polymers adsorbed on the nanowires during the wet synthesis process are carbonized to form a carbon layer. This carbon layer directly connects the active component, the high-entropy alloy nanowire, and the conductive carrier, the carbon nanotube network, forming an integrated carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructure. The carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructure prepared by this method can be directly used as a hydrogen evolution electrode in water electrolysis, exhibiting both high activity and high stability, and is expected to find applications in water electrolysis for hydrogen production.

[0075] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention are within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructure, characterized in that, In a high-quality, self-supporting carbon nanotube macrostructure network, ultrafine high-entropy alloy nanowires are wet-grown using acetylacetone salts of different metals as precursors and surfactants as templates. Rapid heating is used to carbonize the surfactants, forming a nitrogen-doped carbon layer uniformly coating the surface of the ultrafine high-entropy alloy nanowires. This nitrogen-doped carbon layer connects the ultrafine high-entropy alloy nanowires and carbon nanotube bundles to form an integrated composite macrostructure. The composition and size of the ultrafine high-entropy alloy nanowires are controlled by altering the type of precursor source, heating temperature, and time during synthesis. The thickness, crystallinity, and nitrogen doping amount of the coating carbon layer are controlled by adjusting the composition and amount of the surfactant and the rapid heating temperature. The metals in the prepared ultrafine high-entropy alloy nanowires are transition metals or noble metals. The transition metals are selected from Fe, Co, Ni, Cu, Mo, W, Re, and Ta, and the noble metals are selected from Au, Ag, Pt, Pd, Ru, Rh, and Ir. The total number of transition metals and noble metals is greater than or equal to 5. The ultrafine high-entropy alloy nanowires have a length of 10~500 nm and a diameter of 2.0~5.0 nm. The oil bath heating temperature range is 100~300 ℃ and the heating time is 2~120 min. The rapid heating carbonization temperature range is 600~1200 ℃ and the heating time is 5~60 s. The composite macrostructure is directly used as an electrocatalytic hydrogen evolution electrode. The nitrogen-doped carbon layer in the composite macrostructure simultaneously improves catalytic activity and stability. Under acidic conditions, the hydrogen evolution reaction can be carried out at a current density of 10 mA / cm². 2 The overpotential is only 20 mV, and it operates stably for 200 h without decay.

2. The method for preparing carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructures according to claim 1, characterized in that, The high-quality self-supporting carbon nanotube macrostructure used consists of a network of single-walled carbon nanotubes, double-walled carbon nanotubes, or few-walled carbon nanotubes. The macrostructure is a film, fiber, or sponge, and it has the characteristics of high conductivity, self-support, and adjustable size.

3. The method for preparing carbon-coated ultrafine high-entropy alloy nanowire / carbon nanotube composite macrostructures according to claim 1, characterized in that, This macroscopic composite is widely used in the fields of energy storage and conversion, including electrocatalytic hydrogen evolution, electrocatalytic carbon dioxide reduction, and electrocatalytic ammonia synthesis.

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