A high-entropy alloy carbon nanofiber material, a preparation method thereof and application thereof

Abstract

The application relates to a high-entropy alloy carbon nanofiber material and a preparation method and application thereof. The preparation method of the high-entropy alloy carbon nanofiber material comprises the following steps: S1. polyacrylonitrile is prepared into first spinning liquid, electrostatic spinning is carried out, and first nanofiber film is prepared; S2. polyvinylpyrrolidone, a cobalt source, a nickel source, a copper source, a zirconium source and a metal M source are prepared into second spinning liquid, the second spinning liquid is electrostatically spun, the formed second nanofiber film is covered on one face of the first nanofiber film, and a composite nanofiber film is obtained; and S3. the composite nanofiber film is subjected to pre-oxidation and carbonization treatment, and the high-entropy alloy carbon nanofiber material is obtained. The high-entropy alloy carbon nanofiber material has good flexibility and good hydrogen evolution catalytic performance brought by high content of active substances, and the preparation method does not need to use noble metals as raw materials.

Description

Technical Field

[0001] This invention relates to the field of electrocatalytic materials technology, and more specifically, to a high-entropy alloy carbon nanofiber material, its preparation method, and its application. Background Technology

[0002] To reduce fossil fuel consumption and address the environmental pollution caused by it, a new energy source is needed to replace fossil fuels. Hydrogen energy, due to its green and environmentally friendly characteristics, has become a viable alternative. Electrolysis of water is a common method for hydrogen production; however, the low efficiency of the hydrogen evolution reaction (HER) is generally considered a bottleneck in hydrogen production technology. To improve HER efficiency, utilizing electrocatalysts to promote reaction kinetics and reduce the overall overpotential of water splitting is an effective method. Noble metal catalysts exhibit excellent catalytic performance in hydrogen production; for example, the molybdenum-ruthenium alloy catalyst, its preparation method, and applications require the addition of the precious metal ruthenium. However, the high price and scarcity of precious metals pose significant challenges to the application of such catalysts, thus necessitating the exploration of other types of electrocatalysts.

[0003] In addition, most of the catalysts reported so far are in powder form, which requires external stirring to maintain suspension during use and is difficult to recycle after use, thus preventing large-scale application. The molybdenum-ruthenium alloy catalyst mentioned above also has this problem.

[0004] Catalysts prepared using high-voltage electrospinning machines possess a certain shape and flexibility, overcoming the problem of catalyst recovery. However, the most widely used conventional electrospinning method uses polyacrylonitrile (PAC). Most methods involve directly spraying the catalyst after carbonization with all metal elements incorporated into the PAC spinning solution. However, inorganic metal salts have poor solubility in PAC spinning solutions, limiting the synthesis of high-metal-content supported catalysts. Furthermore, metal loading significantly affects the flexibility of the catalyst formed from the PAC spinning solution, making it difficult to simultaneously achieve high active material content and good flexibility.

[0005] Therefore, it is necessary to overcome the problems of current hydrogen evolution catalysts requiring precious metals, being difficult to recycle, and the difficulty of achieving both high active material content and good flexibility in catalysts obtained by electrospinning. Summary of the Invention

[0006] The primary objective of this invention is to overcome the problems of current hydrogen evolution catalysts requiring precious metals, being difficult to recycle, and the difficulty in simultaneously achieving high active material content and good flexibility in catalysts obtained by electrospinning. This invention provides a method for preparing high-entropy alloy carbon nanofiber materials. The high-entropy alloy carbon nanofiber materials obtained by this method simultaneously possess good flexibility and excellent hydrogen evolution catalytic performance (including good catalytic activity and catalytic stability) due to high active material content. Furthermore, due to its good flexibility, the high-entropy alloy carbon nanofiber materials can be recycled multiple times. In addition, the preparation method of this invention does not require precious metals as raw materials to achieve good catalytic performance, significantly reducing the preparation cost.

[0007] A further objective of this invention is to provide a high-entropy alloy carbon nanofiber material.

[0008] A further objective of this invention is to provide the application of the aforementioned high-entropy alloy carbon nanofiber material in the electrocatalytic hydrogen evolution reaction.

[0009] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0010] A method for preparing a high-entropy alloy carbon nanofiber material includes the following steps:

[0011] S1. Polyacrylonitrile is prepared into a first spinning solution, and electrospinning is performed to obtain a first nanofiber membrane;

[0012] S2. Prepare a second spinning solution by taking polyvinylpyrrolidone, cobalt source, nickel source, copper source, zirconium source and metal M source, and perform electrospinning on the second spinning solution so that the formed second nanofiber membrane covers one side of the first nanofiber membrane to obtain a composite nanofiber membrane.

[0013] S3. The composite nanofiber membrane is pre-oxidized and carbonized to obtain the high-entropy alloy carbon nanofiber material.

[0014] The metal M is at least one of molybdenum, zinc, iron, aluminum, or titanium.

[0015] The preparation method of this invention first involves electrospinning a first spinning solution containing polyacrylonitrile to obtain a first nanofiber membrane, which serves as a substrate. Then, a second spinning solution containing polyvinylpyrrolidone and specific metal elements is used as the second spinning solution. The second spinning solution is then electrospun, and the resulting second nanofiber membrane is coated onto one surface of the first nanofiber membrane to obtain a composite nanofiber membrane. This membrane is then subjected to pre-oxidation and carbonization treatments to obtain a high-entropy alloy carbon nanofiber material. Because electrospinning and composite processes are performed sequentially, and because polyvinylpyrrolidone has good compatibility with various metal sources, the flexibility resulting from spinning, pre-oxidation, and carbonization with the first spinning solution, as well as the high content of metal active substances loaded after spinning, pre-oxidation, and carbonization with the second spinning solution, are obtained. Therefore, the high-entropy alloy carbon nanofiber material of this invention simultaneously possesses good flexibility and excellent hydrogen evolution catalytic performance (including good catalytic activity and catalytic stability) due to the high content of active substances. Specifically, high-entropy alloy carbon nanofiber materials are constructed by loading a high content of alloy nanoparticles onto carbon nanofibers. The size of these alloy nanoparticles ranges from 30 to 100 nm. During hydrogen evolution, at a current density of 100 mA / cm², [the material exhibits high entropy]. -2 At this time, the overpotential is below 110mV, and the catalytic activity is good; the Tafel slope is 73mV dec. -1 The material exhibits excellent catalytic stability. Furthermore, due to its good flexibility, the high-entropy alloy carbon nanofiber material can be recycled multiple times. In addition, the preparation method of this invention does not require precious metals as raw materials to achieve good catalytic performance, significantly reducing the preparation cost.

[0016] If the first and second spinning solutions are used simultaneously instead of sequentially, electrostatic repulsion will cause stratification, making it difficult for the active metal material to be well loaded onto the nanofiber membrane. This results in low catalytic activity and poor flexibility of the catalyst. The composition of the alloy metal elements is also crucial; the absence of one or more metal elements will lead to poor catalytic activity.

[0017] Preferably, the metal M is zinc. Using zinc as the metal M results in higher entropy alloy carbon nanofiber materials with better hydrogen evolution catalytic performance.

[0018] Preferably, the metal source M is zinc nitrate.

[0019] Preferably, the concentration of polyacrylonitrile in the first spinning solution is 8-10 wt%.

[0020] Preferably, the solvent of the first spinning solution is N,N-dimethylformamide.

[0021] Preferably, the electrospinning voltage in step S1 is 12-14 kV, the distance from the receiving device to the needle is 15-20 cm, and the solution flow rate is 0.006-0.009 mL / min.

[0022] Preferably, the cobalt source in step S2 is one or more of cobalt chloride, cobalt nitrate, cobalt sulfate, or cobalt bromide.

[0023] Preferably, the nickel source in step S2 is one or more of nickel chloride, nickel nitrate, nickel sulfate, or nickel bromide.

[0024] Preferably, the copper source in step S2 is one or more of copper chloride, copper nitrate, copper sulfate, or copper bromide.

[0025] Preferably, the zirconium source in step S2 is zirconium boride.

[0026] Using zirconium boride allows high-entropy alloy carbon nanofiber materials to maintain good hydrogen evolution catalytic activity while also improving flexibility.

[0027] Preferably, the concentration of polyvinylpyrrolidone in the second spinning solution is 6-10 wt%.

[0028] Preferably, the solvent of the second spinning solution is N,N-dimethylformamide.

[0029] Preferably, the molar ratio of cobalt, nickel, copper, zirconium and M in the second spinning solution is (1-2):(1-2):(0.5-1):(0.5-1):(0.5-1).

[0030] Preferably, the molar concentration of cobalt in the second spinning solution is 1 to 2 mol / L.

[0031] Preferably, the molar concentration of nickel in the second spinning solution is 1 to 2 mol / L.

[0032] Preferably, the molar concentration of copper in the second spinning solution is 0.5 to 1 mol / L.

[0033] Preferably, the molar concentration of zirconium in the second spinning solution is 0.5–1 mol / L.

[0034] Preferably, the molar concentration of element M in the second spinning solution is 0.5 to 1 mol / L.

[0035] Preferably, the electrospinning voltage in step S2 is 18-20kV, the distance from the receiving device to the needle is 15-20cm, and the solution flow rate is 0.009-0.012mL / min.

[0036] By adjusting the electrospinning parameters within a specific range, the first and second nanofiber membranes can be better combined, resulting in higher active material loading, better hydrogen evolution catalytic activity, and better flexibility in the high-entropy alloy carbon nanofiber material.

[0037] Preferably, the pre-oxidation process further includes a drying step.

[0038] More preferably, the drying temperature is 60°C to 80°C, and the drying time is 8 to 12 hours.

[0039] Preferably, the pre-oxidation conditions in step S3 are: holding at 220–260°C for 1.5–3 hours. More preferably, holding at 250°C for 2 hours. Under these conditions, the high-entropy alloy carbon nanofiber material exhibits better hydrogen evolution catalytic activity.

[0040] Preferably, the carbonization is carried out in an inert atmosphere.

[0041] Preferably, the carbonization conditions in step S3 are: holding at 600-800°C for 2-4 hours.

[0042] A high-entropy alloy carbon nanofiber material was prepared by the above-described preparation method.

[0043] The application of the aforementioned high-entropy alloy carbon nanofiber materials in the electrocatalytic hydrogen evolution reaction is also within the scope of protection of this invention.

[0044] Preferably, the high-entropy alloy carbon nanofiber material is used as a working electrode in the electrocatalytic hydrogen evolution reaction.

[0045] Compared with the prior art, the beneficial effects of the present invention are:

[0046] The high-entropy alloy carbon nanofiber material prepared by the method of this invention possesses both excellent flexibility and good hydrogen evolution catalytic performance (including good catalytic activity and catalytic stability) due to its high content of active substances. Furthermore, due to its excellent flexibility, the high-entropy alloy carbon nanofiber material can be recycled multiple times. In addition, the preparation method of this invention does not require precious metals as raw materials to achieve good catalytic performance, significantly reducing the preparation cost. Attached Figure Description

[0047] Figure 1 This is a microscopic morphology image of the CoNiCuZrZn / CNFs sample in Example 1.

[0048] Figure 2 This is a sample image of the CoNiCuZrZn / CNFs sample from Example 1.

[0049] Figure 3This is a schematic diagram of the flexible bending of the CoNiCuZrZn / CNFs sample in Example 1.

[0050] Figure 4 a is the linear sweep voltammetric curve of the CoNiCuZrZn / CNFs sample in Example 1; Figure 4 b is the Tafel slope diagram of the CoNiCuZrZn / CNFs sample of Example 1.

[0051] Figure 5 This is a microscopic morphology image of the CoNiCuZrMo / CNFs sample in Example 2.

[0052] Figure 6 a is the linear sweep voltammetric curve of the CoNiCuZrMo / CNFs sample in Example 2; Figure 6 b is the Tafel slope diagram of the CoNiCuZrMo / CNFs sample of Example 2.

[0053] Figure 7 a is the linear sweep voltammetric curve of the CoNiCuZrZn-1 / CNFs sample in Example 3; Figure 7 b is the Tafel slope diagram of the CoNiCuZrZn-1 / CNFs sample of Example 3.

[0054] Figure 8 a is the linear sweep voltammetric curve of the CoNiCuZr / CNFs sample in Comparative Example 1; Figure 8 b. Tafel slope plot of the CoNiCuZr / CNFs sample of Comparative Example 1.

[0055] Figure 9 The image shows the microstructure of the CoNiCuZrZn-2 / CNFs sample from Comparative Example 2.

[0056] Figure 10 a is the linear sweep voltammetric curve of the CoNiCuZrZn-2 / CNFs sample of Comparative Example 2; Figure 10 b is the Tafel slope plot of the CoNiCuZrZn-2 / CNFs sample of Comparative Example 2.

[0057] Figure 11 a is the linear sweep voltammetric curve of the Co / CNFs sample in Comparative Example 3; Figure 11 b. Tafel slope plot of the Co / CNFs sample in Comparative Example 3.

[0058] Figure 12 The image shows the microstructure of the CoNiCuZrZn-3 / CNFs sample from Comparative Example 4.

[0059] Figure 13a is the linear sweep voltammetric curve of the CoNiCuZrZn-3 / CNFs- sample of Comparative Example 4; Figure 13 b is the Tafel slope plot of the CoNiCuZrZn-3 / CNFs sample of Comparative Example 4.

[0060] Figure 14 The image shows the microstructure of CNFs sample from Comparative Example 5.

[0061] Figure 15 a is the linear sweep voltammetric curve of CNFs sample in Comparative Example 5; Figure 15 b is the Tafel slope plot of CNFs sample in Comparative Example 5. Detailed Implementation

[0062] To more clearly and completely describe the technical solution of the present invention, the present invention will be further described in detail below through specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. Various changes can be made within the scope of the claims of the present invention.

[0063] Example 1

[0064] This embodiment provides a method for preparing high-entropy alloy carbon nanofiber materials, including the following steps:

[0065] 1. Take 6 mL of N,N-dimethylformamide solution with a pipette, add 0.6 g of polyacrylonitrile, and stir evenly by magnetic heating to obtain the first spinning solution. Then, load the solution into a syringe and spray it out using electrospinning. Control the voltage at 14 kV, the distance between the needle and the receiving plate at 15 cm, and the spraying speed at 0.006 mL / min to obtain the first nanofiber membrane.

[0066] 2. Take 2 mL of N,N-dimethylformamide solution with a pipette, add 4 mmol of cobalt nitrate, 4 mmol of nickel nitrate, 2 mmol of copper nitrate, 2 mmol of zirconium boride, and 2 mmol of zinc nitrate, then add 0.3 g of polyvinylpyrrolidone. Stir the solution evenly by magnetic heating to obtain the second spinning solution. Then, load the solution into a syringe and use electrospinning to spray the second spinning solution. Control the voltage at 20 kV, the distance between the needle and the receiving plate at 15 cm, and the spraying speed at 0.012 mL / min, so that the second nanofiber membrane formed by the second spinning solution covers one side of the first nanofiber membrane, thus obtaining a composite nanofiber membrane.

[0067] 3. Take out the composite nanofiber membrane spun in step 2 as a whole, put it in an oven and dry it at 60℃ for 12 hours;

[0068] 4. The dried composite nanofiber membrane is placed in a muffle furnace for pre-oxidation: the temperature is increased to 250℃ at a rate of 5℃ / min and held at this temperature for 2 hours in air. After pre-oxidation, the membrane is removed and placed in a tube furnace. Argon gas is introduced, and the temperature is increased to 600℃ at a rate of 3℃ / min and held for 2 hours. Then, the temperature is increased to 800℃ at a rate of 2℃ / min and held for calcination for 2 hours. After the calcination is completed, the temperature is lowered to room temperature in an argon atmosphere to obtain the high-entropy alloy carbon nanofiber material, denoted as CoNiCuZrZn / CNFs.

[0069] Morphological characterization: SEM images of CoNiCuZrZn / CNFs were taken, and the morphological images are shown below. Figure 1 As shown, from Figure 1 It is known that CoNiCuZrZn / CNFs has a porous structure. The carbon nanofibers in CoNiCuZrZn / CNFs have a diameter of 300–600 nm, and the alloy nanoparticles supported on the high-entropy carbon nanofibers have a size of 30–100 nm. Figure 2 This is a sample image of CoNiCuZrZn / CNFs.

[0070] Performance testing:

[0071] a. Flexibility Test: Take CoNiCuZrZn / CNFs and cut it into a 1cm*1cm sample. Use tweezers to bend the sample at both ends. If the sample can bend without breaking, it indicates good flexibility; if the sample breaks after bending, it indicates poor flexibility. Figure 3 As shown, the CoNiCuZrZn / CNFs in this embodiment can bend without breaking, indicating that the high-entropy alloy carbon nanofiber material of the present invention has good flexibility.

[0072] b. Electrocatalytic performance testing: The HER performance was tested in a 1M KOH solution using a three-electrode system. In this embodiment, CoNiCuZrZn / CNFs was used as the working electrode (1cm*1cm), Ag / AgCl as the reference electrode, and a carbon rod as the counter electrode. Linear sweep voltammetry was performed with a scan range of 0 to -0.4V and a scan rate of 5mV / s. Figure 4 As shown in figure a. Based on the linear sweep voltammetry curve, the Tafel slope can be obtained, such as... Figure 4 As shown in b. During the hydrogen evolution process, when the current density reaches 100 mA / cm², -2 At that time, the overpotential of CoNiCuZrZn / CNFs was 72mV, meaning that a certain current density was achieved with a relatively small voltage / charge ratio, indicating that the high-entropy alloy carbon nanofiber material of this invention has good hydrogen evolution catalytic performance; while the Tafel slope was 51mV dec. -1The low level indicates that the high-entropy alloy carbon nanofiber material of the present invention has good catalytic stability and its catalytic reaction rate has a good response in different electrode potential ranges.

[0073] Example 2

[0074] This embodiment provides a method for preparing high-entropy alloy carbon nanofiber materials, which is basically the same as that in Example 1, except that the 2 mmol zinc nitrate in step 2 is replaced with 2 mmol molybdenum chloride. The resulting high-entropy alloy carbon nanofiber material is denoted as CoNiCuZrMo / CNFs.

[0075] Morphological characterization: SEM images of CoNiCuZrMo / CNFs were taken, and the morphological images are shown below. Figure 5 As shown, from Figure 5 It is known that CoNiCuZrMo / CNFs has a porous structure. The diameter of the carbon nanofibers in CoNiCuZrMo / CNFs is 300-600 nm, and the size of the alloy nanoparticles loaded on the high-entropy carbon nanofibers is 30-100 nm.

[0076] Performance testing:

[0077] a. Flexibility test: The test method is the same as in Example 1. The CoNiCuZrMo / CNFs in this example can be bent without breaking, indicating that the high-entropy alloy carbon nanofiber material of the present invention has good flexibility.

[0078] b. Electrocatalytic performance testing: The HER performance was tested in a 1M KOH solution using a three-electrode system. In this embodiment, CoNiCuZrMo / CNFs was used as the working electrode, Ag / AgCl as the reference electrode, and a carbon rod as the counter electrode. Linear sweep voltammetry was performed with a scan range of 0 to -0.4 V and a scan rate of 5 mV / s. Figure 6 As shown in figure a. Based on the linear sweep voltammetry curve, the Tafel slope can be obtained, such as... Figure 6 As shown in b. During the hydrogen evolution process, when the current density reaches 100 mA / cm², -2 At that time, the overpotential of CoNiCuZrMo / CNFs was 77mV, meaning that a certain current density was achieved with a relatively small voltage / charge ratio, indicating that the high-entropy alloy carbon nanofiber material of this invention has good hydrogen evolution catalytic performance; while the Tafel slope was 56mV dec. -1 The low level indicates that the high-entropy alloy carbon nanofiber material of the present invention has good catalytic stability and its catalytic reaction rate has a good response in different electrode potential ranges.

[0079] Example 3

[0080] This embodiment provides a method for preparing high-entropy alloy carbon nanofiber materials, which is basically the same as that in Example 1, except that the pre-oxidation process in step 4 is as follows: the temperature is increased to 220°C at a heating rate of 2°C / min, held at this temperature in air for 2 hours, and then increased to 260°C at a heating rate of 1°C / min, held in air for 1 hour. The resulting high-entropy alloy carbon nanofiber material is denoted as CoNiCuZrZn-1 / CNFs.

[0081] Morphological characterization: SEM images of CoNiCuZrZn-1 / CNFs showed that its morphology was similar to that of CoNiCuZrZn / CNFs.

[0082] Performance testing:

[0083] a. Flexibility test: The test method is the same as in Example 1. The CoNiCuZrZn-1 / CNFs in this example can be bent without breaking, indicating that the high-entropy alloy carbon nanofiber material of the present invention has good flexibility.

[0084] b. Electrocatalytic performance testing: The HER performance was tested in a 1M KOH solution using a three-electrode system. In this embodiment, CoNiCuZrZn-1 / CNFs was used as the working electrode, Ag / AgCl as the reference electrode, and a carbon rod as the counter electrode. Linear sweep voltammetry was performed with a scan range of 0 to -0.4 V and a scan rate of 5 mV / s. Figure 7 As shown in figure a. Based on the linear sweep voltammetry curve, the Tafel slope can be obtained, such as... Figure 7 As shown in b. During the hydrogen evolution process, when the current density reaches 100 mA cm⁻¹. -2 At that time, the overpotential of CoNiCuZrZn-1 / CNFs was 110mV, meaning that a certain current density was achieved with a relatively small voltage / charge ratio, indicating that the high-entropy alloy carbon nanofiber material of this invention has good hydrogen evolution catalytic performance; while the Tafel slope was 73mV dec. -1 The low level indicates that the high-entropy alloy carbon nanofiber material of the present invention has good catalytic stability and its catalytic reaction rate has a good response in different electrode potential ranges.

[0085] Comparative Example 1

[0086] This comparison provides a method for preparing alloy carbon nanofiber materials, which is basically the same as that in Example 1, except that:

[0087] In step 2, zinc nitrate is not added. The resulting alloy carbon nanofiber material is denoted as CoNiCuZr / CNFs.

[0088] Performance testing:

[0089] a. Flexibility test: The test method is the same as in Example 1. The CoNiCuZr / CNFs in this comparative example can be bent without breaking, demonstrating good flexibility.

[0090] b. Electrocatalytic performance testing: The HER performance was tested in a 1M KOH solution using a three-electrode system. The CoNiCuZr / CNFs electrode from this comparative example was used as the working electrode, the Ag / AgCl electrode as the reference electrode, and a carbon rod as the counter electrode. Linear sweep voltammetry was performed with a scan range of 0 to -0.4 V and a scan rate of 5 mV / s. Figure 8 As shown in figure a. Based on the linear sweep voltammetry curve, the Tafel slope can be obtained, such as... Figure 8 As shown in b. During the hydrogen evolution process, when the current density reaches 100 mA cm⁻¹. -2 At that time, the overpotential of CoNiCuZr / CNFs was 175mV, meaning that a relatively large voltage / charge was required to reach a certain current density, indicating that the hydrogen evolution catalytic performance of the alloy carbon nanofiber material in this comparative example was poor; while the Tafel slope was 96mV dec. -1 The rate is relatively high, indicating that the catalytic stability of the alloy carbon nanofiber material in this comparative example is poor, and its catalytic reaction rate varies greatly in different electrode potential ranges.

[0091] Comparative Example 2

[0092] This comparative study provides a method for preparing alloy carbon nanofiber materials, which is basically the same as that in Example 1, except that steps 1 and 2 are combined into one step for simultaneous spinning. Specifically, 6 mL of N,N-dimethylformamide solution is taken with a pipette, and 0.6 g of polyacrylonitrile is added. The mixture is stirred evenly by magnetic heating to obtain the first spinning solution, which is then loaded into a syringe. Simultaneously, 2 mL of N,N-dimethylformamide solution is taken with a pipette, and 4 mmol of cobalt nitrate, 4 mmol of nickel nitrate, 2 mmol of copper nitrate, 2 mmol of zirconium boride, and 2 mmol of zinc nitrate are added. Then, 0.3 g of polyvinylpyrrolidone is added. The mixture is stirred evenly by magnetic heating to obtain the second spinning solution, which is then loaded into another syringe. Both spinning solutions are simultaneously sprayed out using electrospinning, with the voltage controlled at 16 kV, the distance between the needle and the receiving plate at 15 cm, and the spraying speed at 0.009 mL / min. The spun composite nanofiber membrane is then removed as a whole and subjected to the same drying, pre-oxidation, and carbonization treatment as in steps 3 and 4 of Example 1. The resulting alloy carbon nanofiber material is denoted as CoNiCuZrZn-2 / CNFs.

[0093] Morphological characterization: SEM images of CoNiCuZrZn-2 / CNFs were taken, such as... Figure 9 As shown, from Figure 9It can be seen that CoNiCuZrZn-2 / CNFs has a porous structure, but the loading of active material is low.

[0094] Performance testing:

[0095] a. Flexibility test: The test method is the same as in Example 1. The CoNiCuZrZn-2 / CNFs sample in this comparative example cracked after bending, indicating that it has poor flexibility.

[0096] b. Electrocatalytic performance testing: The HER performance was tested in a 1M KOH solution using a three-electrode system. The CoNiCuZrZn-2 / CNFs electrode from this comparative example was used as the working electrode, the Ag / AgCl electrode as the reference electrode, and a carbon rod as the counter electrode. Linear sweep voltammetry was performed with a scan range of 0 to -0.4 V and a scan rate of 5 mV / s. Figure 10 As shown in figure a. Based on the linear sweep voltammetry curve, the Tafel slope can be obtained, such as... Figure 10 As shown in b. During the hydrogen evolution process, when the current density reaches 100 mA cm⁻¹. -2 At that time, the overpotential of CoNiCuZrZn-2 / CNFs was 260mV, meaning that a relatively large voltage / charge was required to reach a certain current density, indicating that the hydrogen evolution catalytic performance of the alloy carbon nanofiber material in this comparative example was poor; while the Tafel slope was 130mV dec. -1 The rate is relatively high, indicating that the catalytic stability of the alloy carbon nanofiber material in this comparative example is poor, and its catalytic reaction rate varies greatly in different electrode potential ranges.

[0097] Comparative Example 3

[0098] This comparison provides a method for preparing carbon nanofiber materials, which is basically the same as that in Example 1, except that:

[0099] In step 2, nickel nitrate, copper nitrate, zirconium boride, and zinc nitrate are not added. The resulting carbon nanofiber material is denoted as Co / CNFs.

[0100] Performance testing:

[0101] a. Flexibility test: The test method is the same as in Example 1. The Co / CNFs in this comparative example can be bent without breaking, demonstrating good flexibility.

[0102] b. Electrocatalytic performance testing: The HER performance was tested in a 1M KOH solution using a three-electrode system. The Co / CNFs electrode from this comparative example was used as the working electrode, the Ag / AgCl electrode as the reference electrode, and a carbon rod as the counter electrode. Linear sweep voltammetry was performed with a scan range of 0 to -0.4 V and a scan rate of 5 mV / s. Figure 11As shown in figure a. Based on the linear sweep voltammetry curve, the Tafel slope can be obtained, such as... Figure 11 As shown in b. During the hydrogen evolution process, when the current density reaches 100 mA cm⁻¹. -2 At that time, the overpotential of Co / CNFs was 220mV, meaning that a relatively large voltage / charge was required to reach a certain current density, indicating that the hydrogen evolution catalytic performance of the alloy carbon nanofiber material in this comparative example was poor; while the Tafel slope was 112mV dec. -1 This indicates that the carbon nanofiber material in this comparative example has poor catalytic stability, and its catalytic reaction rate varies greatly across different electrode potential ranges.

[0103] Comparative Example 4

[0104] This comparative study provides a method for preparing alloy carbon nanofiber materials, which is basically the same as that in Example 1, except that the pre-oxidation process in step 4 is omitted. The final alloy carbon nanofiber material is denoted as CoNiCuZrZn-3 / CNFs.

[0105] Morphological characterization: SEM images of CoNiCuZrZn-3 / CNFs were taken, such as... Figure 12 As shown, from Figure 12 It can be seen that CoNiCuZrZn-3 / CNFs is not a porous structure.

[0106] Performance testing:

[0107] a. Flexibility test: The test method is the same as in Example 1. The CoNiCuZrZn-3 / CNFs sample in this comparative example cracked after bending, indicating that it has poor flexibility.

[0108] b. Electrocatalytic performance testing: The HER performance was tested in a 1M KOH solution using a three-electrode system. The CoNiCuZrZn-3 / CNFs electrode from this comparative example was used as the working electrode, the Ag / AgCl electrode as the reference electrode, and a carbon rod as the counter electrode. Linear sweep voltammetry was performed with a scan range of 0 to -0.4 V and a scan rate of 5 mV / s. Figure 13 As shown in figure a. Based on the linear sweep voltammetry curve, the Tafel slope can be obtained, such as... Figure 13 As shown in b. During the hydrogen evolution process, when the current density reaches 100 mA cm⁻¹. -2 At that time, the overpotential of CoNiCuZrZn-3 / CNFs was 385mV, meaning that a large voltage / charge was required to reach a certain current density, indicating that the hydrogen evolution catalytic performance of the alloy carbon nanofiber material in this comparative example was poor; while the Tafel slope was 324mV dec. -1The level is very high, indicating that the catalytic stability of the alloy carbon nanofiber material in this comparative example is poor, and its catalytic reaction rate varies greatly in different electrode potential ranges.

[0109] Comparative Example 5

[0110] This comparative study provides a method for preparing carbon nanofiber materials, which is basically the same as that in Example 1, except that step 2 is omitted. That is, after obtaining the first nanofiber membrane in step 1, steps 3 and 4 (drying, pre-oxidation, and carbonization) are performed immediately. The final carbon nanofiber material is denoted as CNFs.

[0111] Morphological characterization: CNFs were photographed using SEM, such as... Figure 14 As shown in Figure 14, CNFs are complete filamentous structures.

[0112] Performance testing:

[0113] a. Flexibility test: The test method is the same as in Example 1. The CNFs in this comparative example can bend without breaking, demonstrating good flexibility.

[0114] b. Electrocatalytic performance testing: The HER performance was tested in a 1M KOH solution using a three-electrode system. CNFs from this comparative example were used as the working electrode, an Ag / AgCl electrode as the reference electrode, and a carbon rod as the counter electrode. Linear sweep voltammetry was performed with a scan range of 0 to -0.4 V and a scan rate of 5 mV / s. Figure 15 As shown in figure a. Based on the linear sweep voltammetry curve, the Tafel slope can be obtained, such as... Figure 15 As shown in b, the linear sweep voltammetry curve and Tafel slope of the CNFs sample indicate that it has virtually no catalytic performance.

[0115] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a high-entropy alloy carbon nanofiber material, characterized in that, Comprising the following steps: S1. polyacrylonitrile is prepared into a first spinning solution, electrospinning is carried out, and a first nanofiber membrane is prepared; S2. polyvinylpyrrolidone, a cobalt source, a nickel source, a copper source, a zirconium source and a metal M source are prepared into a second spinning solution, electrospinning is carried out on the second spinning solution, the second nanofiber membrane formed is covered on one face of the first nanofiber membrane, and a composite nanofiber membrane is obtained; S3. The composite nanofiber membrane is subjected to pre-oxidation and carbonization treatment, and the high-entropy alloy carbon nanofiber material is obtained; The metal M is zinc; and the zirconium source is zirconium boride; The molar concentration of cobalt in the second spinning solution is 1-2 mol / L; the molar concentration of nickel in the second spinning solution is 1-2 mol / L; the molar concentration of copper in the second spinning solution is 0.5-1 mol / L; the molar concentration of zirconium in the second spinning solution is 0.5-1 mol / L; and the molar concentration of M in the second spinning solution is 0.5-1 mol / L.

2. The method of claim 1, wherein, The concentration of polyacrylonitrile in the first spinning solution is 8-10 wt%.

3. The preparation method according to claim 1, characterized in that, The spinning voltage of the electrospinning in step S1 is 12-14 kV, the distance from the receiving device to the needle is 15-20 cm, and the solution flow rate is 0.006-0.009 mL / min.

4. The preparation method according to claim 1, characterized in that, The concentration of polyvinylpyrrolidone in the second spinning solution is 6-10 wt%.

5. The method of claim 1, wherein the step of forming the first and second layers is performed by a process selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. The molar ratio of cobalt, nickel, copper, zirconium and M in the second spinning solution is (1-2):(1-2):(0.5-1):(0.5-1):(0.5-1).

6. The method of claim 1, wherein the step of forming the first and second layers is performed by a process selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. The spinning voltage of the electrospinning in step S2 is 18-20 kV, the distance from the receiving device to the needle is 15-20 cm, and the solution flow rate is 0.009-0.012 mL / min.

7. The method of claim 1, wherein the step of forming the first and second layers is performed by a process selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. The pre-oxidation condition in step S3 is: incubation at 220-260℃ for 1.5-3 hours.

8. A high-entropy alloy carbon nanofiber material, characterized in that, Prepared by any one of the preparation methods in claims 1-7.

9. The application of the high-entropy alloy carbon nanofiber material in claim 8 in an electrocatalytic hydrogen evolution reaction.

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