Coral-like iron-cobalt-nickel-aluminum-molybdenum high-entropy alloy catalytic material, preparation method and application thereof

Abstract

The present application belongs to the technical field of catalytic materials, and particularly relates to a coralline FeCoNiAlMo high-entropy alloy catalytic material and a preparation method thereof, and application of the material in alkaline water oxygen evolution reaction. By precisely regulating the concentration ratio of five elements of iron, cobalt, nickel, aluminum and molybdenum in electrolyte, a FeCoNiAlMo high-entropy alloy coralline structure (abbreviated as FeCoNiAlMo HEA) is directly grown on the surface of a clean nickel mesh by using a direct current constant current co-deposition method. The prepared FeCoNiAlMo HEA catalytic electrode has high reaction activity and fast mass transfer rate, and also has excellent stability and excellent catalytic effect under a large current density. By dual regulation of components and structure, the present application solves the problems of mass transfer obstruction and insufficient stability caused by the use of a binder in the application of traditional high-entropy materials, and provides a new solution to the poor performance of industrialized electrodes under a large current density.

Description

Technical Field

[0001] This invention belongs to the field of catalytic electrode technology, specifically relating to a coral-like iron-cobalt-nickel-aluminum-molybdenum high-entropy alloy catalytic material and its preparation method, as well as the application of this electrode in the alkaline water oxygen evolution reaction. Background Technology

[0002] Hydrogen production through water electrolysis can convert green electricity generated from renewable energy sources such as photovoltaics and wind power into hydrogen for storage, potentially solving the problem of renewable energy consumption. Hydrogen production technologies include alkaline water (ALK) electrolysis, proton exchange membrane (PEM) electrolysis, and anion exchange membrane (AEM) electrolysis. Among these, ALK electrolysis, as the earliest industrially applied hydrogen production technology, has broad application prospects.

[0003] Water electrolysis can be divided into the cathode hydrogen evolution reaction (HER) and the anodic oxygen evolution reaction (OER). The OER reaction, acting as the kinetic bottleneck of water splitting, suffers from a high overpotential due to the slow four-electron transfer process in alkaline media, severely limiting the overall energy conversion efficiency of hydrogen production via water electrolysis. Therefore, constructing a high-performance OER catalytic electrode is crucial. Currently, industrial water electrolysis typically uses a nickel mesh (Raney nickel) coated with nickel-aluminum alloy particles as the anode to promote the OER reaction. The nickel mesh substrate not only possesses excellent conductivity but also its woven mesh structure facilitates the escape of bubbles during the reaction, preventing bubble accumulation from obscuring active sites. Furthermore, the surface-coated nickel-aluminum particles undergo surface reconstruction to form hydroxyl oxides during the OER catalytic reaction, serving as active sites to promote the reaction. However, limited by the activity of existing catalytic electrodes, the current density for ALK (Alternating Current Kinematics) hydrogen production is typically less than 500 mA·cm⁻¹. -2 This results in low energy conversion efficiency and high energy consumption in electrolyzers, leading to high hydrogen production costs. Therefore, developing high-performance catalytic electrodes with high catalytic activity and good stability under high current densities is of great significance.

[0004] Transition metal alloys, oxides, phosphides, and sulfides have attracted widespread attention due to their advantages such as low cost and tunable composition. Since single transition metal elements often exhibit low catalytic activity, researchers have increasingly opted for multi-element mixtures to prepare alloy catalysts, aiming to improve the electrochemical performance of materials. Among these, high-entropy alloys (HEAs) composed of five (or more) elements demonstrate unique advantages. High-entropy HEAs with high mixing entropy exhibit a unique cocktail effect; the doping of different elements causes lattice distortion, creating more active sites at the microscopic level and significantly enhancing catalytic performance. Currently, commonly used methods for synthesizing high-entropy alloys include high-energy ball milling and high-temperature annealing. These preparation techniques are typically complex and have long synthesis cycles. Furthermore, since the final product is often in the form of solid powder or bulk particles, it requires a binder to coat it onto a conductive substrate, resulting in high contact resistance. Moreover, catalyst detachment can occur under high current density conditions, hindering practical applications.

[0005] In summary, providing a mild and simple process for preparing high-performance transition metal-based catalytic electrodes with high catalytic activity and good stability under high current density is of significant technical importance. Summary of the Invention

[0006] To address the problems existing in the prior art, one objective of this invention is to provide a method for preparing a coral-like high-entropy alloy catalytic material of iron, cobalt, nickel, aluminum, and molybdenum. Specifically, a coral-like high-entropy alloy material of iron, cobalt, nickel, aluminum, and molybdenum is in situ grown on the surface of a nickel mesh using a co-electrode deposition method, and then used as an integrated electrode in an OER reaction under high current density. The modified catalytic material not only possesses the advantages of high conductivity and fast bubble escape rate of pure nickel mesh, but also exhibits high reactivity and mass transfer rate. Furthermore, it demonstrates excellent performance under operating conditions, making it valuable for industrial applications.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a method for preparing a coral-like iron-cobalt-nickel-aluminum-molybdenum high-entropy alloy catalytic material, comprising the following steps:

[0008] S1. Dissolve Fe2(SO4)3, NiSO4, CoSO4, Al2(SO4)3, Na2MoO4, (NH4)2SO4 and trisodium citrate in deionized water with a molar concentration ratio of 1:2:2:1:4:4:4, wherein the molar concentration of Fe2(SO4)3 is 0.2-0.3 M. Adjust the pH of the solution to 4.0-7.0 to obtain an electrodeposition solution.

[0009] S2. A dual-electrode electrodeposition system is employed, using a clean and activated nickel mesh as the cathode and a graphite sheet electrode as the anode, placed in an electrodeposition solution at 50-200 mA·cm⁻¹.-2 Coral-like high-entropy alloy catalyst material of iron, cobalt, nickel, aluminum, and molybdenum was obtained by co-electrodeposition at a current density for 1-2 h, denoted as FeCoNiAlMo high-entropy catalyst material.

[0010] Further improvements were made to the preparation method of a coral-like high-entropy alloy catalytic material made of iron, cobalt, nickel, aluminum, and molybdenum:

[0011] Preferably, in step S2, the method for preparing the surface-cleaned and activated nickel mesh is as follows: after cutting the nickel mesh, immerse it sequentially in a 1.0-3.0 M hydrochloric acid solution, acetone, and deionized water for ultrasonic cleaning for 10-20 min to obtain a surface-cleaned nickel mesh.

[0012] Preferably, the nickel mesh is cut to a size of 1cm. 1cm to 5cm A rectangular piece with an arbitrary area within a 5 cm interval.

[0013] Preferably, in step S1, NaOH solution is added dropwise to adjust the pH of the electrodeposition solution.

[0014] Preferably, in step S2, the nickel mesh is cleaned with deionized water after deposition.

[0015] The second objective of this invention is to provide a coral-like iron-cobalt-nickel-aluminum-molybdenum high-entropy alloy catalytic material prepared by any of the above-mentioned methods.

[0016] The third objective of this invention is to provide an application of the above-mentioned coral-like iron-cobalt-nickel-aluminum-molybdenum high-entropy alloy catalytic material in the alkaline water oxygen evolution reaction.

[0017] Further improvements to the application of coral-like iron-cobalt-nickel-aluminum-molybdenum high-entropy alloy catalysts in the alkaline oxygen evolution reaction:

[0018] Preferably, this FeCoNiAlMo high-entropy catalytic material is used as an integrated electrode in the OER reaction of alkaline water electrolysis for hydrogen production at high current density.

[0019] Preferably, the current density is not less than 1000 mA·cm -2 .

[0020] Preferably, the electrolyte for the alkaline OER reaction is a 1.0-6.0 M KOH electrolyte.

[0021] The advantages of this invention compared to the prior art are as follows:

[0022] (1) This invention provides a method for preparing a coral-like high-entropy alloy catalytic material of iron, cobalt, nickel, aluminum, and molybdenum. The invention employs a DC constant current co-deposition method, precisely controlling the concentration ratio of five elements (iron, cobalt, nickel, aluminum, and molybdenum) in the electrolyte to directly grow a coral-like high-entropy alloy structure in situ on a clean nickel mesh surface. This method is simple, with mild reaction conditions, and achieves the construction of an integrated electrode. This strategy not only fully utilizes the high conductivity of the nickel mesh substrate but, more importantly, avoids the use of binders in traditional electrode preparation, thus solving the problems of binders covering active sites, hindering mass transfer, and causing catalysts to easily detach under high current densities. This simplifies the process, significantly reduces catalyst synthesis costs, and effectively utilizes the characteristics of high-entropy alloys, providing a feasible path for the industrial preparation of high-performance catalytic electrodes.

[0023] (2) The catalytic electrode of this invention is a coral-like high-entropy alloy structure formed by the uniform mixing of five elements—iron, cobalt, nickel, aluminum, and molybdenum—at the atomic level. This multi-component high-entropy alloy has a high mixing entropy and forms chemical bonds adapted to the atomic size and electronic structure of multiple components through various hybridization methods, thereby reducing the system energy. This multi-component high-entropy alloy also has a significant lattice distortion effect, forming abundant catalytic active sites at the atomic scale. At the same time, as the electrochemical reaction proceeds, aluminum in the system slowly dissolves, increasing the electrochemical active area, thereby improving the catalytic performance of the electrode at both the macroscopic and microscopic levels. Its unique coral-like three-dimensional structure greatly increases the electrochemical active area. Meanwhile, the slow dissolution of aluminum during the electrochemical reaction further forms a porous structure, further promoting mass transfer. The synergistic effect of components and structure, from the microscopic atomic arrangement to the macroscopic three-dimensional morphology level, jointly optimizes the catalytic performance of the electrode. The prepared catalytic electrode exhibits excellent performance under operating conditions and has potential for industrial application.

[0024] (3) The high-entropy alloy catalytic electrode of the present invention not only possesses the high conductivity and fast bubble escape rate of pure nickel mesh, but also exhibits high reactivity and significantly improved mass transfer rate. Furthermore, the in-situ grown integrated electrode avoids the use of binders in traditional electrodes, preventing the active sites from being covered by binders and inhibiting the detachment of catalyst particles from the electrode surface under high current density. This results in excellent electrocatalytic activity and outstanding stability at high current densities in the alkaline oxygen evolution reaction. In 1.0 M KOH electrolyte, it achieves 10 and 1000 mA·cm⁻¹. -2 The required current density is only 194.8 and the overpotential is 426.2 mV. An alkaline water electrolyzer assembled with these as electrodes operates under simulated industrial conditions (1000 mA·cm⁻¹). -2 It requires only about 1.9 V to operate. Furthermore, it demonstrated excellent stability during a 600-hour testing period, with a voltage decay rate as low as 0.2 mV·h. -1This invention solves the problem of mass transfer obstruction and insufficient stability caused by the use of binders in traditional high-entropy material applications through dual regulation of composition and structure. Its superior performance solves the problem of insufficient activity and stability of traditional electrodes at high current densities, providing a new solution for high-performance anode electrodes for industrial water electrolysis to produce hydrogen. Attached Figure Description

[0025] Figure 1 The synthesis flow chart shows the synthesis process of a coral-shaped high-entropy alloy catalytic electrode made of iron, cobalt, nickel, aluminum, and molybdenum.

[0026] Figure 2 The structure characterization diagram of the FeCoNiAlMo HEA catalytic electrode prepared in Example 1 is shown in (a) SEM image of pure nickel mesh; (b) and (c) SEM images of catalytic electrodes of different sizes; (d) TEM image; (e) HRTEM, electron diffraction and lattice fringe image; (f) corresponding elemental distribution diagram.

[0027] Figure 3 (a) XRD spectra of FeCoNi, FeCoNiAl, FeCoNiMo, and FeCoNiAlMo HEA catalytic electrodes; (b), (c), (d), (e), and (f) are, in order, the Ni 2p, Fe 2p, Co 2p, and Mo 3d XPS spectra of the FeCoNiAlMo HEA catalytic electrode and the local XPS full spectrum containing Al 2p.

[0028] Figure 4 The OER electrocatalytic performance of Ni Mesh, FeCoNi, FeCoNiAl, FeCoNiMo, FeCoNiAlMo HEA catalytic electrodes and industrial Raney nickel electrodes was characterized; (a) LSV curve after 95% iR compensation; (b) OER electrocatalytic performance of FeCoNiAlMo HEA catalytic electrode and FeCoNi, FeCoNiAl, FeCoNiMo catalytic electrodes at 10 mA·cm⁻¹. -2 100mA·cm -2 1000 mA·cm -2 Comparison of overpotentials at current densities; (c) Tafel slope; (d) Electrochemical impedance spectroscopy; (e) Double-layer capacitance C. dl (f) shows the FeCoNiAlMo HEA catalytic electrode and the recently reported OER catalyst at 10 mA·cm⁻¹. -2 Performance comparison of overpotential and Tafel slope at current density; (g) is 1000 mA·cm -2 Stability test under high current density.

[0029] Figure 5(a), (b), (c), and (d) are the CV spectra of FeCoNi, FeCoNiAl, FeCoNiMo, and FeCoNiAlMo HEA catalytic electrodes measured in the non-Radida region, respectively, and (e) is the LSV curve after ECSA normalization.

[0030] Figure 6 In Figures (a) and (b), the FeCoNiAlMo HEA catalytic electrode prepared in Example 1 is subjected to 600 h of exposure to 30 wt% KOH at room temperature and 1000 mA·cm⁻¹. -2 SEM images at different magnifications after the complete water splitting test; (c) shows the results of the complete water splitting test at room temperature with 30 wt% KOH; (d) shows the schematic diagram of the electrolyzer structure under simulated operating conditions; (e) shows the results of the simulated operating conditions test and the comparison system. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0032] Example 1

[0033] This embodiment provides a method for preparing a coral-shaped iron-cobalt-nickel-aluminum-molybdenum high-entropy alloy catalytic electrode, which specifically includes the following steps:

[0034] S1. Cut the nickel mesh to a size of 5 cm. A 5 cm rectangular sheet was immersed in 3.0 M hydrochloric acid solution, acetone, and deionized water respectively and ultrasonically cleaned for 10 min to obtain a nickel mesh with a clean and activated surface.

[0035] Fe2(SO4)3, NiSO4, CoSO4, Al2(SO4)3, Na2MoO4, (NH4)2SO4 and trisodium citrate were dissolved in deionized water in a molar ratio of 1:2:2:1:4:4:4, with the molar concentration of Fe2(SO4)3 being 0.25 M. An appropriate amount of NaOH solution was added dropwise to adjust the pH of the mixed solution to 6.0 to obtain an electrodeposition solution.

[0036] S2. A dual-electrode electrodeposition system is used, with a clean and activated nickel mesh as the cathode and a graphite sheet electrode as the anode, placed in the electrodeposition solution at 200 mA·cm⁻¹. -2 Coral-shaped iron-cobalt-nickel-aluminum-molybdenum high-entropy alloy catalytic electrode was obtained by co-electrodeposition at a current density for 1 h, denoted as FeCoNiAlMo HEA.

[0037] Example 2

[0038] This embodiment provides a method for preparing a coral-shaped iron-cobalt-nickel-aluminum-molybdenum high-entropy alloy catalytic electrode. The specific steps are the same as in Example 1, except that the molar concentration of Fe2(SO4)3 in S1 is 0.2 M and the pH is 4.0.

[0039] A coral-like high-entropy alloy catalytic electrode made of iron, cobalt, nickel, aluminum, and molybdenum was obtained, denoted as FeCoNiAlMo HEA-1 catalytic electrode.

[0040] Example 3

[0041] This embodiment provides a method for preparing a coral-shaped iron-cobalt-nickel-aluminum-molybdenum high-entropy alloy catalytic electrode. The specific steps are the same as in Example 1, except that the molar concentration of Fe2(SO4)3 in S1 is 0.3 M and the pH is 7.0.

[0042] A coral-like high-entropy alloy catalytic electrode made of iron, cobalt, nickel, aluminum, and molybdenum was obtained, denoted as FeCoNiAlMo HEA-2 catalytic electrode.

[0043] Example 4

[0044] This embodiment provides a method for preparing a coral-shaped iron-cobalt-nickel-aluminum-molybdenum high-entropy alloy catalytic electrode. The specific steps are the same as in Example 1, except that the current density in S2 is 100 mA·cm. -2 The time is 1 hour.

[0045] A coral-like high-entropy alloy catalytic electrode made of iron, cobalt, nickel, aluminum, and molybdenum was obtained, denoted as FeCoNiAlMo HEA-3 catalytic electrode.

[0046] Example 5

[0047] This embodiment provides a method for preparing a coral-shaped iron-cobalt-nickel-aluminum-molybdenum high-entropy alloy catalytic electrode. The specific steps are the same as in Example 1, except that the current density in S2 is 50 mA·cm. -2 The time is 2 hours.

[0048] A coral-like high-entropy alloy catalytic electrode made of iron, cobalt, nickel, aluminum, and molybdenum was obtained, denoted as FeCoNiAlMo HEA-4 catalytic electrode.

[0049] Comparative Example 1

[0050] This comparative example provides a method for preparing a FeCoNiMo catalytic electrode. The specific steps are the same as in Example 1, except that Al2(SO4)3 was not added to the electrodeposition solution. The FeCoNiMo catalytic electrode was finally obtained.

[0051] Comparative Example 2

[0052] This comparative example provides a method for preparing a FeCoNiAl catalytic electrode. The specific steps are the same as in Example 1, except that Na2MoO4 was not added to the electrodeposition solution. The FeCoNiAl catalytic electrode was finally obtained.

[0053] Comparative Example 3

[0054] This comparative example provides a method for preparing a FeCoNi catalytic electrode. The specific steps are the same as in Example 1, except that Al2(SO4)3 and Na2MoO4 are not added to the electrodeposition solution. The FeCoNi catalytic electrode is finally obtained.

[0055] Performance Testing: The samples were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and X-ray energy dispersive spectroscopy (EDS). Electrochemical tests were performed in 1.0 M KOH solution using a standard three-electrode testing system. The prepared FeCoNiAlMo HEA catalytic electrode, Hg / HgO electrode, and graphite rod electrode were used as the working electrode, reference electrode, and counter electrode, respectively. The linear sweep voltammetry (LSV) test rate was 2 mV·s. -1 Electrochemical impedance spectroscopy (EIS) was performed at frequencies ranging from 100 kHz to 0.01 Hz with an amplitude of 5 mV. Cyclic voltammetry (CV) was used to measure potentials in the non-Radida region (1.177–1.277 V vs. RHE) with scan rates ranging from 20 to 100 mV·s. -1 To obtain the electrochemical double-layer capacitance (C2) of the catalyst. dl ).

[0056] (1) Morphology and structural characterization of electrodes

[0057] like Figure 1 The diagram shows a flowchart of the electrodeposition of FeCoNiAlMo high-entropy alloy particles on a nickel mesh surface using a dual-electrode deposition apparatus.

[0058] Figure 2The following are structural characterization images of the FeCoNiAlMo HEA catalytic electrode prepared in Example 1. (a) is a SEM image of a pure nickel mesh, showing a smooth surface. (b) and (c) are SEM images of the catalytic electrode at different sizes, showing that the FeCoNiAlMo high-entropy alloy particles exhibit coral-like growth on the nickel mesh surface with numerous grooves. (d) is a TEM image; the image shows that the coral-like structure is composed of several nanoscale particles. (e) are HRTEM, electron diffraction, and lattice fringe images; lattice fringes with a spacing of 0.206 nm are observed, corresponding to the (111) crystal plane of the FCC crystal structure. The electron diffraction pattern also shows obvious diffraction rings belonging to the (111) crystal plane. Furthermore, the magnified lattice fringes are bent, further confirming the generation of lattice distortion. (f) is an energy-dispersive X-ray spectroscopy (EDS) image, showing a uniform distribution of Fe, Co, Ni, Al, and Mo elements, further confirming the successful preparation of the FeCoNiAlMo HEA catalytic electrode. The elemental ratios of the sample were determined using inductively coupled plasma atomic emission spectrometry (ICP-AES). The final atomic ratios of Fe, Co, Ni, Al, and Mo were 27.3:26.4:25.1:7.4:13.8, and the mixing entropy ΔS mix =1.519 R>1.5R, which conforms to the high entropy characteristic.

[0059] The prepared FeCoNiAlMo HEA catalytic electrode and FeCoNi, FeCoNiAl, and FeCoNiMo catalytic electrodes were characterized by XRD structure, as follows: Figure 3 As shown in (a), diffraction peaks appear at 44.4°, 52.1°, and 75.6°, corresponding to the (111), (200), and (220) crystal planes of the Ni face-centered cubic (FCC) structure, respectively. With the increase of element types, the diffraction peaks gradually broaden, and the FeCoNiAlMoHEA catalytic electrode only shows a broad peak at around 44.4°; the wider peak area is attributed to the lattice distortion caused by the doping of other elements. TEM and XRD test results both indicate that the crystallinity of the FeCoNiAlMo high-entropy alloy particles is reduced due to the doping of Al and Mo elements.

[0060] To further explore the surface chemical bonding state of the samples, X-ray photoelectron spectroscopy (XPS) characterization was performed. The Ni 2p spectrum of the FeCoNiAlMo HEA catalytic electrode surface was analyzed, and the results are as follows: Figure 3 As shown in (b), it is composed of Ni 2p 3 / 2 (856.1 eV; 857.6 eV), Ni 2p 1 / 2 The presence of two spin orbital pairs (874.8 eV; 876.3 eV) and two satellite peaks (abbreviated as "sat.") indicates the existence of Ni.2+ and Ni 3+ The secondary peaks at 855.1 eV and 872.8 eV belong to metallic Ni. Similarly, for the Fe 2p spectrum and Co 2p ( Figure 3 (c), 3(d)), from Fe 2p 3 / 2 (716.1 eV; 712.5 eV), Fe 2p 1 / 2 (725.4 eV; 721.7 eV) and Co 2p 3 / 2 (797.1 eV; 802.3 eV), Co 2p 1 / 2 The spin-orbit pairs (784.3 eV; 781.1 eV) correspond to Fe, respectively. 2+ and Fe 3+ and Co 3+ and Co 2+ The spectra of Fe and Co show no obvious metallic peaks, which may be due to surface oxidation during the synthesis process. Meanwhile, Mo 3d ( Figure 3 (e)) and Al 2p ( Figure 3 (f) In the spectrum, peaks appear at 231.2 eV and 74.5 eV, respectively, corresponding to Mo. 6+ And Al 3+4+ XPS tests revealed the metallic bonding properties of the FeCoNiAlMo HEA catalytic electrode.

[0061] (2) Oxygen evolution reaction performance

[0062] Using 1.0 M KOH solution as the electrolyte, the OER performance of Ni mesh, FeCoNi, FeCoNiAl, FeCoNiMo, FeCoNiAlMo HEA catalytic electrodes, and industrial Raney nickel electrodes was tested using a standard three-electrode testing system. Linear sweep voltammetry (LSV) curves were used. Figure 4 (a) shows that the OER activity of the FeCoNiAlMo HEA catalytic electrode is far superior to that of ternary and quaternary catalytic electrodes, and also has advantages over the widely used Raney nickel electrode. The FeCoNiAlMo HEA catalytic electrode at 10 mA·cm⁻¹ exhibits significantly better OER activity than its ternary and quaternary counterparts. -2 100 mA·cm -2 and 1000 mA·cm -2 The overpotentials at the current densities were 194.8 mV, 270.9 mV, and 426.2 mV, respectively, significantly better than other catalysts, demonstrating its excellent electrocatalytic activity. Furthermore, at the same current density ( Figure 4(b) The OER performance of the FeCoNiAlMo HEA catalytic electrode is significantly better than that of the FeCoNi, FeCoNiAl and FeCoNiMo catalytic electrodes, which proves that the multi-element synergistic "cocktail effect" of high-entropy alloys improves catalytic performance.

[0063] Meanwhile, the OER performance of FeCoNiAlMo HEA-1 and FeCoNiAlMo HEA-2, FeCoNiAlMo HEA-3 and FeCoNiAlMo HEA-4 prepared in Examples 2, 3, 4 and 5 were tested respectively. FeCoNiAlMo HEA-1 showed an OER performance of 10 mA·cm⁻¹. -2 100mA·cm -2 and 1000 mA·cm -2 The overpotentials at current densities were 197.8 mV, 275.3 mV, and 430.2 mV, respectively; FeCoNiAlMo HEA-2 at 10 mA·cm⁻¹... -2 100 mA·cm -2 and 1000 mA·cm -2 The overpotentials at current densities were 196.2 mV, 273.2 mV, and 431.2 mV, respectively; FeCoNiAlMo HEA-3 at 10 mA·cm⁻¹... -2 100 mA·cm -2 and 1000mA·cm -2 The overpotentials at current densities were 200.2 mV, 275.3 mV, and 432.2 mV, respectively; FeCoNiAlMo HEA-4 at 10 mA·cm⁻¹... -2 100 mA·cm -2 and 1000 mA·cm -2 The overpotentials at the current densities were 201.3 mV, 276.7 mV, and 431.3 mV, respectively, all demonstrating its excellent electrocatalytic activity.

[0064] To conduct a deeper analysis of OER dynamics, Figure 4 (c) shows the Tafel slope corresponding to the polarization curve. In the low to high current density range, the Tafel slope of the FeCoNiAlMo HEA catalytic electrode is 57.8 mV dec. -1 This indicates that the material has a fast reaction kinetics process and a high mass transfer efficiency. Figure 4 The EIS test results shown in (d) also verify this result, in which the FeCoNiAlMo HEA catalytic electrode exhibits the minimum charge transfer resistance (R0). ctThis confirms its excellent electronic conductivity and efficient charge transfer kinetics. Furthermore, based on double-layer capacitance (C... dl The relationship between the surface area and the electrochemically active surface area (ECSA) is directly proportional, and analysis shows that... Figure 4 (e)), C of FeCoNiAlMo HEA catalytic electrode dl It is 12.41 mF·cm -2 The value is higher than that of the FeCoNi catalytic electrode (5.75 mF·cm⁻¹). -2 ) and FeCoNiMo catalytic electrode (7.43 mF·cm) -2 This indicates that the incorporation of Al significantly increased the electrochemical active area of ​​the catalytic electrode, and the partial dissolution of aluminum during the electrochemical testing process provided the catalytic electrode with more active sites. A comparison was made with advanced OER catalysts reported in existing literature (as shown in Table 1 below). Figure 4 (f)), FeCoNiAlMo HEA catalytic electrode at Tafel slope and 10 mA·cm -2 The overpotential at current density showed significant advantages. Furthermore, catalyst stability, as a core performance indicator, plays a crucial role in applications, such as... Figure 4 As shown in (g), the stability of the prepared sample was evaluated by constant current testing, requiring only a potential of 1.656 (V vs. RHE) to drive 1000 mA·cm. -2 The high current density and stable operation for 500 hours without significant performance degradation indicate that the prepared FeCoNiAlMo HEA catalytic electrode material has excellent long-term stability at high current densities.

[0065] Table 1 Catalytic electrodes reported in existing literature

[0066]

[0067] To demonstrate the intrinsic catalytic activity of the catalyst, cyclic voltammetry curves (e.g., for ternary, quaternary, and FeCoNiAlMo HEA catalytic electrodes) were measured at different scan rates within the non-Radar region. Figure 5 (a), (b), (c) and (d) are shown in the figures. After ECSA normalization, the ECSA-normalized LSV curves of the FeCoNiAlMo HEA catalytic electrode are shown. Figure 5 (e) still has the smallest overpotential, indicating that the FeCoNiAlMo HEA catalytic electrode has more active sites per unit active area, which is beneficial to the electrochemical OER.

[0068] (3) Mechanism of oxygen evolution reaction

[0069] To investigate the changes occurring in the FeCoNiAlMo HEA catalytic electrode during the oxygen evolution reaction (OER), XPS measurements were performed on the FeCoNiAlMo HEA catalytic electrode after the OER reaction (e.g., ...). Figure 3 In (b), (c), (d), (e), and (f), compared with the XPS results before the OER test, all zero-valent metal peaks completely disappeared, and only high-valent metal valence states remained. The peaks of Fe, Co, and Ni all shifted to lower binding energies. Furthermore, since high-valent nickel acts as an active intermediate during the OER process, it spontaneously reduces to the more stable Ni after the reaction. 2+ From the spectrum ( Figure 3 (b) shows that Ni 3+ The peak area of ​​Fe decreased significantly, while Fe 3+ and Co 3+ ( Figure 3 The peak areas of (c) and (d) are significantly increased. Mo element ( Figure 3 The significantly reduced peak area corresponding to (e) indicates that Mo dissolves during the OER process, leading to a weakening of the Mo signal. The peaks belonging to Al ( Figure 3 (f) No significant change indicates that Al does not participate in the OER process, but only partially dissolves during the reaction to form active sites and increase the electrochemical active area.

[0070] (4) Testing under operating conditions

[0071] To verify the stability of the prepared FeCoNiAlMo HEA catalytic electrode under high-concentration alkaline solutions and high current densities, and its application value under operating conditions, a total water splitting system (FeCoNiAlMo || FeCoNiAlMo) was constructed using the prepared FeCoNiAlMo HEA catalytic electrode as both the anode and cathode. A 30% KOH solution (approximately 6.0 M molar concentration) was selected as the electrolyte. The test temperature was room temperature, and the current density was 1000 mA·cm⁻¹. -2 Perform a complete water lysis test. For tests conducted over a long period of time (… Figure 6 (a), Figure 6 (b) The OER reaction electrode material was characterized by SEM. The results showed that, under high electrolyte concentration, the particles on the modified electrode surface did not significantly detach after ampere-level current density testing, indicating high material stability and resistance to alkaline corrosion. It also demonstrated excellent catalytic performance under harsh conditions, further proving the advantages of in-situ grown catalysts as "integrated structure electrodes." At room temperature ( Figure 6 (c) The total water splitting system can achieve 1000 mA·cm at a voltage of 2.03 V. -2The current density increased to 2.15 V after 600 h of testing, with a decay rate of only 0.2 mV·h. -1 Subsequently, in a test environment of 30% KOH solution and 85 °C, the prepared FeCoNiAlMo HEA catalytic electrode was used as the anode and cathode, respectively, to assemble an alkaline water electrolysis cell system (FeCoNiAlMo || FeCoNiAlMo). Figure 6 (d) The electrolytic cell system reaches 1000 mA·cm -2 The voltage required for the current density is approximately 1.9 V. Figure 6 (e) During this period, the voltage rise caused by electrolyte consumption can be recovered to a relatively good performance after electrolyte replenishment. Meanwhile, under the same test conditions, iridium dioxide and platinum-carbon catalysts supported on nickel foam were used as the anode and cathode (IrO2 || Pt / C) in the same alkaline water hydrogen production system. The test results showed that its performance under high temperature and high concentration alkaline conditions was far inferior to that of the FeCoNiAlMo HEA catalytic electrode alkaline water hydrogen production system, and its stability was poor, with its performance continuously declining in the first few hours. Through the above tests, the FeCoNiAlMo HEA catalytic electrode demonstrated excellent performance under operating conditions, providing feasibility for its practical application.

[0072] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments. It should be noted that many modifications and improvements can be made by those skilled in the art, and all modifications or improvements not exceeding the scope of the claims should be considered within the protection scope of the present invention.

Claims

1. A method for preparing a coral-like Fe-Co-Ni-Al-Mo high-entropy alloy catalytic material, characterized in that, Includes the following steps: S1. Dissolve Fe2(SO4)3, NiSO4, CoSO4, Al2(SO4)3, Na2MoO4, (NH4)2SO4 and trisodium citrate in deionized water with a molar concentration ratio of 1:2:2:1:4:4:4, wherein the molar concentration of Fe2(SO4)3 is 0.2-0.3 M. Adjust the pH of the solution to 4.0-7.0 to obtain an electrodeposition solution. S2. A dual-electrode electrodeposition system is employed, using a clean and activated nickel mesh as the cathode and a graphite sheet electrode as the anode, placed in an electrodeposition solution at 50-200 mA·cm⁻¹. -2 Coral-shaped high-entropy alloy catalytic electrode was obtained by co-electrodeposition at a current density for 1-2 h, denoted as FeCoNiAlMo high-entropy catalytic material.

2. The method for preparing the coral-like iron-cobalt-nickel-aluminum-molybdenum high-entropy alloy catalytic material according to claim 1, characterized in that, In step S2, the preparation method of the surface-cleaned and activated nickel mesh is as follows: After cutting the nickel mesh, immerse it in 1.0-3.0 M hydrochloric acid solution, acetone, and deionized water in sequence for ultrasonic cleaning for 10-20 min to obtain a surface-cleaned nickel mesh.

3. The method for preparing the coral-like iron-cobalt-nickel-aluminum-molybdenum high-entropy alloy catalytic material according to claim 2, characterized in that, Nickel mesh cut to size 1 cm 1 cm to 5 cm Rectangular pieces of any area in the interval 5 cm.

4. The method for preparing the coral-like iron-cobalt-nickel-aluminum-molybdenum high-entropy alloy catalytic material according to claim 1, characterized in that, In step S1, NaOH solution is added dropwise to adjust the pH of the electrodeposition solution.

5. The method for preparing the coral-like iron-cobalt-nickel-aluminum-molybdenum high-entropy alloy catalytic material according to claim 1, characterized in that, In step S2, the nickel mesh is cleaned with deionized water after deposition.

6. A coral-like iron-cobalt-nickel-aluminum-molybdenum high-entropy alloy catalytic material prepared by the preparation method of any one of claims 1-5.

7. The application of the coral-like iron-cobalt-nickel-aluminum-molybdenum high-entropy alloy catalytic material as described in claim 6 in the alkaline water oxygen evolution reaction.

8. The use of the coral-like Fe-Co-Ni-Al-Mo high-entropy alloy catalytic material in the alkaline water oxygen evolution reaction according to claim 7, characterized in that, The FeCoNiAlMo high-entropy catalytic material is used as an integrated electrode in the OER reaction of alkaline water electrolysis for hydrogen production at high current density.

9. The use of the coral-like Fe-Co-Ni-Al-Mo high-entropy alloy catalytic material in the alkaline water oxygen evolution reaction according to claim 8, characterized in that, current density is not less than 1000 mA-cm - 2.

10. The application of the coral-like iron-cobalt-nickel-aluminum-molybdenum high-entropy alloy catalytic material according to claim 8 in the alkaline water oxygen evolution reaction, characterized in that, The electrolyte for alkaline OER reactions is a 1.0-6.0 M KOH electrolyte.

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