FeCo-based amorphous nanofiber electrocatalyst as well as preparation method and application thereof

Abstract

The invention discloses a FeCo-based amorphous nanofiber electrocatalyst and a preparation method and application thereof, the FeCo-based amorphous nanofiber electrocatalyst takes a FeCo-based metal strip as the electrocatalyst, the component is Fe40Co (40-x) CuxP13C7, and x is more than or equal to 0 and less than 40. The preparation method comprises the following steps: mixing Fe, Co, Cu, P and C powder according to the atomic percentage of each element, carrying out vacuum smelting, then carrying out high-vacuum electric arc smelting, preparing a uniform strip by a grinding system through a single-roller melt-spinning method, soaking the strip in alcohol, slightly polishing on fine sandpaper to remove an oxide layer so as to enable the strip to be smooth, and carrying out high-temperature sintering. The preparation method comprises the following steps: cleaning and drying the raw materials to obtain a working electrode, taking a saturated calomel electrode as a reference electrode, taking a Pt sheet electrode as a counter electrode, dealloying the working electrode through 0.2 V vs. SCE, and passivating the dealloyed electrode through negative voltage to obtain the FeCo-based amorphous nanofiber electrocatalyst. The FeCo amorphous nanofiber strip is prepared by adopting an electro-dealloying method, has good oxygen evolution catalytic performance and can be used as an oxygen evolution electro-catalyst.

Description

Technical Field

[0001] The present invention belongs to the field of electrocatalytic material applications, and specifically relates to an FeCo-based amorphous nanofiber electrocatalyst and a preparation method thereof, as well as application of the FeCo-based amorphous nanofiber electrocatalyst as an oxygen evolution electrocatalyst in electrocatalytic water decomposition to produce hydrogen. Background Art

[0002] Electrocatalytic water splitting for hydrogen production has attracted considerable attention due to its high efficiency and practicality. A bottleneck in this technology lies in the anodic oxygen evolution reaction (OER), a four-electron transfer process with slow kinetics, resulting in a significantly higher overpotential than the hydrogen evolution reaction (HER). Improving OER catalytic efficiency is crucial for reducing the overall energy consumption of water electrolysis. Furthermore, optimizing OER performance has significant implications for key areas such as metal-air batteries, photocatalytic water splitting for hydrogen production, and photocatalytic ammonia synthesis. Currently, while noble metal-based catalysts (such as Ir, Ru, and their oxides) exhibit excellent OER activity, their scarcity and high cost severely restrict their large-scale application. To overcome this limitation, research has focused on the design and development of low-cost transition metals and their compounds (such as alloys, nitrides, borides, carbides, sulfides, and phosphides). In recent years, a variety of transition metal-based electrocatalysts have been successfully prepared and exhibit catalytic performance comparable to that of noble metals, becoming a research hotspot in this field.

[0003] Fiber structures are a common and highly effective surface morphology in electrocatalysts. Fiber strips, through their unique multidimensional open structure, achieve a synergistic effect in electrocatalysis by maximizing active sites, optimizing mass transfer kinetics, and enhancing structural stability. This has become a core strategy for overcoming the performance bottlenecks of traditional catalysts. In the future, with advances in preparation technology, fiber electrocatalytic materials are expected to promote the large-scale application of green hydrogen production and high-efficiency energy devices, providing a key material foundation for addressing global energy and environmental challenges. Summary of the Invention

[0004] The purpose of the present invention is to prepare FeCo-based amorphous nanofiber electrocatalysts with excellent electrocatalytic activity for efficient oxygen evolution reaction, thereby solving the problems of low current density, high overpotential and poor stability of existing electrocatalysts.

[0005] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions: The present invention first discloses a FeCo-based amorphous nanofiber electrocatalyst, which uses a FeCo-based fiber strip as an electrocatalyst. The structural formula of the FeCo-based strip according to the atomic percentage of each element is: Fe 40 Co 40-x Cu x P 13C7, 0≤x<40, where x is the atomic percentage of Cu element, the density of the electrocatalyst is 7.0-9.0 g / cm 3 , with a specific surface area of ​​18-45m 2 / g, pore size is 20-100nm.

[0006] Preferably, the structural formula of the FeCo-based fiber tape according to the atomic percentage of each element is: Fe 40 Co 37 Cu3P 13 C7, which has the best oxygen evolution catalytic performance after electro-dealloying treatment.

[0007] The present invention also discloses a method for preparing the FeCo-based amorphous nanofiber electrocatalyst, which comprises the following steps: (1) Fe powder, Co powder, Cu powder, P powder and C powder are mixed and prepared according to the atomic percentage of each element, and then placed in a vacuum arc melting furnace. After vacuuming, argon gas is introduced and arc melting is performed. In order to ensure the uniformity of the alloy composition, the master alloy is repeatedly melted in the furnace for not less than 4 times. During each melting process, the phosphorus iron and carbon powder are melted as slowly as possible to prevent the raw materials from volatilizing due to excessive temperature, and the master alloy ingot is obtained; (2) placing the prepared master alloy ingot in a high vacuum arc melting and crushing system, introducing argon gas after vacuuming, and spray casting the original strip at high speed by a single roller strip casting method; (3) Select strips with uniform shape and smooth surface from the original strips, soak the strips in alcohol and lightly polish them on fine sandpaper to remove the oxide layer and make them smooth, then wash and dry them; (4) A standard three-electrode system was used, in which the prepared alloy strip was used as the working electrode, the saturated calomel electrode was used as the reference electrode, and the Pt sheet electrode was used as the counter electrode. The electrolyte was a 0.5 mol / L dilute H2SO4 solution. The strip was first electro-dealloyed at a positive voltage of 0.2 V vs. SCE. To maintain the uniform structure of the strip and prevent excessive corrosion, the duration was controlled at 400 s. The Cu element was then passivated at a negative voltage of -0.1 V vs. SCE to obtain a FeCo-based amorphous nanofiber electrocatalyst.

[0008] In step (4), the voltage of the electrodealloying should be accurately controlled at 0.2 V vs. SCE, otherwise fibers cannot be formed on the surface of the low-voltage strip, and high voltage will cause excessive corrosion and destroy the original surface morphology.

[0009] Preferably, the purity of the Fe, Cu powder and Co powder in step (1) is not less than 99.9wt%, and the purity of the P powder and C powder is not less than 99.00wt%.

[0010] Preferably, the purity of the argon in step (1) is 99.99%.

[0011] Preferably, in step (3), the cleaning is performed by washing with alcohol and deionized water in sequence, and the drying is performed at 45° C. for 0.5 h.

[0012] Another object of the present invention is to provide the use of the above-mentioned FeCo-based amorphous nanofiber electrocatalyst as an oxygen evolution electrocatalyst in the electrocatalytic decomposition of water to produce hydrogen.

[0013] The present invention utilizes an electrodealloying method to prepare nanofiber electrocatalysts. The resulting catalyst exhibits a synergistic effect: maximizing active sites, optimizing mass transfer kinetics, and enhancing structural stability. Experimental results demonstrate that FeCo amorphous nanofibers are excellent electrocatalysts with high electrocatalytic activity and long-term stability in alkaline solutions. Given their low production cost, FeCo-based amorphous nanofiber electrocatalysts represent a promising new electrocatalyst material with great commercial potential.

[0014] The beneficial effects of the present invention are embodied in: 1. The FeCo-based amorphous nanofiber electrocatalyst of the present invention exhibits good electrocatalytic activity in a wide range of compositions, is a good oxygen evolution reaction electrocatalyst, and has broad commercial application prospects.

[0015] 2. The FeCo-based amorphous nanofiber electrocatalyst is prepared by the electrical dealloying method in the present invention. The catalyst is directly prepared by grinding and a short-time dealloying process under different voltages and is directly used as an electrocatalytic electrode. It has good conductivity, simplifies the preparation process, and reduces the introduction of Co. The relatively low-cost Cu is added as a substitute, which has a low preparation cost and good catalytic ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Fe obtained in Example 1 40 Co 37 Cu3P 13 XRD pattern of C7 amorphous nanofiber catalyst material.

[0017] Figure 2 Fe prepared in Example 1 40 Co 37 Cu3P 13 Scanning electron microscopy image of the original C7 strip surface.

[0018] Figure 3 Fe prepared in Example 1 40 Co 37 Cu3P 13 Scanning electron microscopy image of the surface of C7 amorphous nanofiber catalyst.

[0019] Figure 4 Fe obtained in Example 1 40 Co 37 Cu3P 13 C7 amorphous nanofiber catalyst and Fe 40 Co 37 Cu3P 13 Linear sweep voltammetry performance curve of C7 tape in 1 M KOH electrolyte.

[0020] Figure 5 The linear sweep voltammetry performance curves of the original strips obtained in Examples 1-6 in 1 M KOH electrolyte.

[0021] Figure 6 The linear sweep voltammetry performance curves of Comparative Example 1 and Comparative Example 2 are shown.

[0022] Figure 7 The linear sweep voltammetry performance curves of Example 1 and Comparative Example 3 (i.e., performance comparison with and without negative pressure) are shown. DETAILED DESCRIPTION

[0023] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is provided in conjunction with the following embodiments. The following is merely an example and illustration of the concept of the present invention. Any modification, supplement, or substitution of the described specific embodiments by a person skilled in the art, as long as it does not deviate from the concept of the invention or exceed the scope defined by the claims, shall fall within the scope of protection of the present invention.

[0024] The amorphous properties of the amorphous nanofiber catalyst prepared in the embodiment of the present invention were detected by X-ray diffraction (XRD). The equipment used was: X'Pert Pro MPD X-ray diffractometer, Panalytical, Netherlands.

[0025] The surface morphology was analyzed by field emission scanning electron microscopy (FE-SEM), and the equipment model used was SU8020, Hitachi, Japan.

[0026] The electrocatalytic activity was measured using an electrochemical workstation (CHI 760E, manufactured by Shanghai Chenhua, China).

[0027] Example 1: Fe 40 Co 37 Cu3P 13 Preparation of C7 amorphous nanofiber catalyst The components of the FeCo-based amorphous nanofiber catalyst of this embodiment are Fe, Co, Cu, P and C, and the atomic percentage content of each element is: Fe 40at.%, Co 37at.%, Cu 3at.%, P 13at.%, C 7at.%.

[0028] The specific preparation steps are as follows: (1) According to the atomic percentage of each element, Fe powder, Co powder and Cu powder with a purity of 99.9wt.% and P powder and C powder with a purity of not less than 99.00wt.% are mixed and then placed in a vacuum arc melting furnace. After vacuuming, argon gas with a purity of 99.99% is introduced for arc melting. In order to ensure the uniformity of the alloy composition, the master alloy is repeatedly melted in the furnace for not less than 4 times. During each melting process, the phosphorus iron and carbon powder are melted as slowly as possible to prevent the raw materials from volatilizing due to excessive temperature. Finally, the master alloy ingot is obtained after cooling; (2) placing the master alloy ingot in a high vacuum arc melting and crushing system, introducing 99.99% pure argon gas after evacuation, and spray casting the original strip at high speed by a single roller strip-spinning method; (3) Select strips with uniform shape and smooth surface from the original strips, soak the strips in alcohol and lightly polish them on fine sandpaper to remove the oxide layer and make them smooth. Then, place the carbon paper in deionized water and ultrasonically clean it at 80W power for 20 minutes. Then, use a baking oven to dry the deionized water on the surface of the carbon paper (dry at 45℃ for 0.5h). (4) A standard three-electrode system was used, in which the prepared alloy strip was used as the working electrode, the saturated calomel electrode was used as the reference electrode, and the Pt sheet electrode was used as the counter electrode. The electrolyte was a 0.5 mol / L dilute H2SO4 solution. The alloy strip was first electro-dealloyed at a positive voltage of 0.2 V vs. SCE. To maintain the uniform structure of the strip and prevent excessive corrosion, the duration was controlled at 400 s. The Cu element was then passivated at a negative voltage of -0.1 V vs. SCE to obtain an amorphous nanofiber electrocatalyst.

[0029] The Fe obtained in Example 1 was characterized by X-ray diffraction. 40 Co 37 Cu3P 13 The structure of C7 amorphous nanofiber electrocatalyst, the results are as follows Figure 1 As shown in FIG, there are no additional diffraction peaks on the XRD spectra of the catalyst that has not been dealloyed and the catalyst that has been treated, which indicates that the ribbon is completely amorphous.

[0030] The carbon paper and the Fe 40 Co 37 Cu3P13 The surface morphology of C7 metal amorphous fiber electrocatalyst is shown in Figure 2. Figure 2 、 Figure 3 As shown, it can be seen that the diameter of the pores on the surface of the fiber structure is about 20nm. Through experimental detection and analysis, the density of the electrocatalyst of the present invention is 7.0g / cm 3 , with a specific surface area of ​​45m 2 / g.

[0031] Fe 40 Co 37 Cu3P 13 The test samples of the C7 original strip and the obtained amorphous nanofiber electrocatalyst were used for the electrocatalytic reaction of water electrolysis (oxygen evolution reaction) to conduct electrochemical activity tests: the test samples were clamped on the corresponding electrode clamps and tested using a three-electrode system with linear sweep voltammetry. The electrolyte was 1 M KOH solution and the measurements were made at a scan rate of 5 mV / s.

[0032] Figure 4 The linear sweep voltammetry performance curves of the three samples show that Fe 40 Co 37 Cu3P 13 C7 metal strip at a sample current density of 10 mA cm -2 When the overpotential is 330 mA cm -2 , and Fe 40 Co 37 Cu3P 13 The C7 amorphous nanofiber electrocatalyst has a current density of 10 mA cm -2 The overpotential can reach 280 mA cm -2 , which proves that Fe 40 Co 37 Cu3P 13 The catalytic performance of C amorphous nanofiber electrocatalyst is better than that of the original tape.

[0033] Example 2: Fe 40 Co 39 Cu1P 13 C7 amorphous nanofiber catalyst The difference between Example 2 of the present invention and Example 1 is that the atomic percentage contents of the elements are: Fe 40 at .%, Co 39 at .%, Cu 1 at .%, P 13 at .%, and C 7 at .%.

[0034] The carbon paper and the Fe 40 Co 39 Cu1P 13The surface morphology of the C7 metal amorphous fiber electrocatalyst shows that the diameter of the pores on the fiber structure is about 72nm. Through experimental analysis, the density of the electrocatalyst prepared in Example 2 of the present invention is 8.1 / cm 3 , with a specific surface area of ​​21m 2 / g.

[0035] Example 3: Fe 40 Co 38 Cu2P 13 C7 amorphous nanofiber catalyst The difference between Example 3 of the present invention and Example 1 is that the atomic percentage contents of the elements are: Fe 40 at .%, Co 38 at .%, Cu 2 at .%, P 13 at .%, and C 7 at .%.

[0036] The carbon paper and the Fe 40 Co 38 Cu2P 13 The surface morphology of the C7 metal amorphous fiber electrocatalyst shows that the diameter of the pores on the fiber structure is about 90nm. Through experimental analysis, the density of the electrocatalyst prepared in Example 3 of the present invention is 8.5 / cm 3 , with a specific surface area of ​​19m 2 / g.

[0037] Example 4Fe 40 Co 36 Cu4P 13 C7 amorphous nanofiber catalyst The difference between Example 4 of the present invention and Example 1 is that the atomic percentage contents of the elements are: Fe 40 at .%, Co 36 at .%, Cu 4 at .%, P 13 at .%, and C 7 at .%.

[0038] The carbon paper and the Fe 40 Co 36 Cu4P 13 The surface morphology of the C7 metal amorphous fiber electrocatalyst shows that the diameter of the pores on the fiber structure surface is about 100nm. Through experimental analysis, the density of the electrocatalyst prepared in Example 4 of the present invention is 9.0 / cm 3 , with a specific surface area of ​​18m 2 / g.

[0039] Example 5: Fe 40 Co 20 Cu 20 P13 C7 amorphous nanofiber catalyst The difference between Example 5 of the present invention and Example 1 is that the atomic percentage contents of the elements are: Fe 40 at .%, Co 20 at .%, Cu 20 at .%, P 13 at .%, and C 7 at .%.

[0040] The carbon paper and the Fe 40 Co 20 Cu 20 P 13 The surface morphology of the C7 metal amorphous fiber electrocatalyst shows that the diameter of the pores on the fiber structure is about 89 nm. Through experimental analysis, the density of the electrocatalyst prepared in Example 5 of the present invention is 9.1 / cm 3 , with a specific surface area of ​​19m 2 / g.

[0041] Example 6: Fe 40 Co1Cu 39 P 13 C7 amorphous nanofiber catalyst The difference between Example 6 of the present invention and Example 1 is that the atomic percentage contents of the elements are: Fe 40 at.%, Co 1 at.%, Cu 39 at.%, P 13 at.%, and C 7 at.%.

[0042] The carbon paper and the Fe 40 Co1Cu 39 P 13 The surface morphology of the C7 metal amorphous fiber electrocatalyst shows that the diameter of the pores on the fiber structure is about 75nm. Through experimental analysis, the density of the electrocatalyst prepared in Example 6 of the present invention is 8.9 / cm 3 , with a specific surface area of ​​22m 2 / g.

[0043] Comparative Example 1: Fe 40 Co 40 P 13 C7 nanofiber catalyst The difference between Comparative Example 1 of the present invention and Example 1 is that the atomic percentage contents of the elements are: Fe 40 at .%, Co 40 at .%, Cu 0 at .%, P 13 at .%, and C 7 at .%.

[0044] The carbon paper and the Fe40 Co 40 P 13 The surface morphology of the C7 metal fiber electrocatalyst shows that the diameter of the pores on the fiber structure is about 93nm. Through experimental analysis, the density of the electrocatalyst prepared in Comparative Example 1 is 8.6 / cm 3 , with a specific surface area of ​​20m 2 / g.

[0045] Comparative Example 2Fe 40 Cu 40 P 13 C7 nanofiber catalyst The difference between Comparative Example 2 of the present invention and Example 1 is that the atomic percentage contents of the elements are: Fe 40 at .%, Co 0 at .%, Cu 40 at .%, P 13 at .%, and C 7 at .%.

[0046] The carbon paper and the Fe 40 Cu 40 P 13 The surface morphology of the C7 metal fiber electrocatalyst shows that the diameter of the pores on the fiber structure surface is about 95nm. Through experimental analysis, the density of the electrocatalyst prepared in Comparative Example 2 is 8.5 / cm 3 , with a specific surface area of ​​23m 2 / g.

[0047] Comparative Example 3 The difference between Comparative Example 3 of the present invention and Example 1 is that in the catalyst preparation process (4), the catalyst is dealloyed by a positive voltage of 0.2 V vs. SCE for a time of 400 s, but the passivation treatment by a negative voltage of -0.1 V vs. SCE is not performed.

[0048] The carbon paper and the Fe 40 Cu 40 P 13 The surface morphology of the C7 amorphous metal fiber electrocatalyst shows that the diameter of the pores on the fiber structure surface is about 50nm. Through experimental analysis, the density of the electrocatalyst prepared in Comparative Example 3 is 7.1 / cm 3 , with a specific surface area of ​​43m 2 / g.

[0049] The catalysts prepared in Examples 1-6 and Comparative Examples 1-3 were subjected to electrochemical activity tests, and the test data are shown in Table 1.

[0050]

[0051] As can be seen from Table 1, the catalyst overpotential of Example 1 is the smallest and has the best effect on electrocatalytic hydrogen production. As the Cu content increases, the pore size of the prepared catalyst first decreases and then increases, the specific surface area of ​​the catalyst material also first increases and then decreases, the overpotential of the catalyst first decreases and then increases, and its catalytic effect also first increases and then decreases; when the catalyst does not contain Cu or Co elements, the overpotential of the catalyst becomes significantly larger. It is crucial to increase the voltage for dealloying during the preparation of the catalyst. If there is only positive voltage without negative voltage, the overpotential of the catalyst increases and the catalytic effect decreases.

[0052] In addition, it can be seen from the embodiments of the present invention that the electrocatalyst of the present invention exhibits excellent electrocatalytic activity within a wide range of components and is a good electrocatalyst for oxygen evolution reaction. At the same time, the introduction of Co is reduced, and relatively low-cost Cu is added, which has a lower replacement preparation cost and can also obtain a catalyst with better catalytic ability.

[0053] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A FeCo-based amorphous nanofiber electrocatalyst, characterized in that: Taking FeCo-based catalyst as electrocatalyst, the structural formula according to the atomic percentage of each element is: Fe 40 Co 40-x Cu x P 13 C7, 0≤x<40, where x is the atomic percentage of Cu element, the density of the electrocatalyst is 7.0-9.0 g / cm 3 , with a specific surface area of ​​18-45m 2 / g, pore size is 20-100nm.

2. The FeCo-based amorphous nanofiber electrocatalyst according to claim 1, characterized in that: The structural formula of the FeCo-based amorphous nanofiber electrocatalyst according to the atomic percentage of each element is: Fe 40 Co 37 Cu3P 13 C7.

3. The method for preparing the FeCo-based amorphous nanofiber electrocatalyst according to claim 1, characterized in that: The specific preparation steps are as follows: (1) Fe powder, Co powder, Cu powder, P powder and C powder are mixed according to the atomic percentage of each element, and then placed in a vacuum arc melting furnace. After vacuuming, argon gas is introduced and arc melting is carried out. The master alloy is repeatedly melted in the furnace for not less than 4 times to obtain a master alloy ingot; (2) The master alloy ingot is melted and smelted, and a uniform strip is prepared by a single-roll strip-throwing method in a high vacuum arc melting and crushing system; (3) Select a strip with a smooth surface and stable structure, soak the strip in alcohol, and lightly polish it on fine sandpaper to remove the oxide layer and make it smooth, then clean and dry it; (4) A standard three-electrode system was used, in which the prepared alloy strip was used as the working electrode, the saturated calomel electrode was used as the reference electrode, and the Pt sheet electrode was used as the counter electrode. The electrolyte was a dilute H2SO4 solution. Electrodealloying was first performed by positive voltage, and then passivation treatment was performed by negative voltage to obtain FeCo-based amorphous nanofiber electrocatalyst.

4. The method for preparing the FeCo-based amorphous nanofiber electrocatalyst according to claim 3, characterized in that: The purity of the Fe, Cu and Co powders in step (1) is not less than 99.9 wt %, and the purity of the P and C powders is not less than 99.00 wt %.

5. The method for preparing the FeCo-based amorphous nanofiber electrocatalyst according to claim 3, characterized in that: The purity of the argon gas in step (1) is 99.99%.

6. The preparation method according to claim 3, wherein: In the step (2), the cleaning is carried out by washing with alcohol and deionized water in sequence; and the drying is carried out at 45° C. for 0.5 h.

7. The preparation method according to claim 3, wherein: In the step (4), the electrolyte is a 0.5 mol / L dilute H2SO4 solution.

8. The preparation method according to claim 3, wherein: In the step (4), the electrode is first subjected to electrodealloying at 0.2 V vs. SCE for 400 s, and then passivated at -0.1 V vs. SCE for 5-10 min.

9. Application of the FeCo-based amorphous nanofiber electrocatalyst according to any one of claims 1 to 2 as an oxygen evolution electrocatalyst in electrocatalytic water decomposition to produce hydrogen, wherein the current density is 10 mA cm in a 1 M KOH solution. -2 When the overpotential is 280-440mAcm -2 .

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