A high-entropy alloy composite material for a metal fuel cell and a method of manufacturing the same

Abstract

The application relates to a high-entropy alloy composite material with excellent performance under normal temperature and pressure and applying the high-entropy alloy composite material to water electrolysis. The application uses an electrochemical workstation to carry out constant-voltage electrodeposition on a treated carbon paper surface loaded with high-entropy alloy material NiFeCoZnCuMnCr, explores the influence of various factors on the performance and morphology of the high-entropy alloy composite material, and finds the optimal preparation condition of the high-entropy alloy composite material. By adjusting the total concentration of the precursor solution to 0.21 mol / L ‑1 and the ratio of metal salts to Ni:Fe:Co:Zn:Cu:Mn:Cr=1:5:15:3:1:1:1, a high-entropy alloy composite material with a core-shell structure of a multi-metal hydroxide (NiFeCoZnCuMnCr) LDH shell and a high-entropy alloy NiFeCoZnCuMnCr HEAs core is synthesized, and the OER and HER of the high-entropy alloy composite material reach 100 mA / cm ‑2 The current density requires overpotential of 378 mV and 331 mV, respectively, and excellent electrocatalytic performance is exhibited.

Description

Technical Field

[0001] This invention belongs to the field of battery energy technology, specifically relating to a high-entropy alloy composite material for metal fuel cells and its preparation method. Background Technology

[0002] With rapid economic and social development, global energy demand is constantly increasing. The extensive use of traditional energy sources such as coal and oil has caused serious environmental crises and climate change. Currently, solar, geothermal, wind, and tidal energy are common and usable renewable and clean energy sources. However, the actual utilization rate of these high-quality renewable energy sources is low due to uncontrollable factors such as geography and seasons. Hydrogen energy has an energy density as high as 142 MJ / kg. -1 Hydrogen, with a heating value second only to nuclear energy and several times that of fossil fuels, and abundant on Earth, is one of the most ideal clean energy sources, as its final combustion product is only water. Currently, hydrogen production through fossil fuels, water-gas, and methanol reforming accounts for 96% of industrial hydrogen production. However, traditional hydrogen production technologies are limited by high costs, pollution, and low yields, necessitating the search for greener, more environmentally friendly, and more efficient methods. Photocatalysis and electrocatalytic water splitting for hydrogen production have gradually become research hotspots. Utilizing inexhaustible solar energy, photocatalytic water splitting is the ideal method; however, its practical application is inevitably hindered by cost and efficiency limitations. Electrocatalytic hydrogen production offers many advantages over photocatalytic production, such as higher hydrogen purity and higher production efficiency, making it a relatively more ideal method.

[0003] Electrocatalytic water splitting utilizes an applied voltage for energy. The water electrolysis reaction includes two half-reactions: oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), producing O2 and H2, respectively. Under standard conditions, the thermodynamic equilibrium potential for OER is 1.23 V, and for HER it is 0 V. Due to unfavorable factors such as solution concentration polarization, solution resistance, and interfacial resistance, electron transfer in the water electrolysis reaction is hindered. In practical applications, the voltage required for both OER and HER is higher than the thermodynamic equilibrium potential; this excess voltage is the overpotential. Both OER and HER processes require highly efficient electrocatalysts to reduce the overpotential and improve water electrolysis efficiency. Currently, the best-performing catalysts for electrocatalytic water splitting are noble metals and their derivatives. RuO2 and IrO2 exhibit the best catalytic performance for OER, while Pt has the best catalytic performance for HER. Limited by the cost and stability of noble metals, developing high-performance, low-cost alternatives to noble metal catalysts is crucial.

[0004] Based on this, this application was developed. Summary of the Invention

[0005] This invention addresses the problems of long preparation cycles, high energy consumption, and severe pollution associated with most high-entropy alloy preparation methods, and provides a high-entropy alloy composite material for metal fuel cells. This high-entropy alloy composite material overcomes the shortcomings of existing technologies and exhibits significantly improved catalytic performance, demonstrating excellent electrocatalytic properties.

[0006] The present invention also provides a method for preparing the above-mentioned high-entropy alloy composite material for metal fuel cells under normal temperature and pressure conditions.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for preparing a high-entropy alloy composite material for metal fuel cells includes the following steps:

[0009] 1) Pre-treat the carbon paper;

[0010] 2) Preparation of precursor solution: Using N,N-dimethylformamide (DMF) and acetonitrile (CH3CN) as solvents, a surfactant and a metal chloride salt are added and mixed magnetically at room temperature to obtain the precursor solution; the metal chloride salt is composed of a mixture of nickel chloride hexahydrate NiCl2·6H2O, anhydrous ferric chloride FeCl3, cobalt chloride hexahydrate CoCl2·6H2O, copper chloride dihydrate CuCl2·2H2O, anhydrous zinc chloride ZnCl2, manganese chloride tetrahydrate MnCl2·4H2O, and chromium chloride tetrahydrate CrCl2·4H2O;

[0011] 3) The precursor solution is transferred to the electrolytic cell. A suitable deposition voltage and time are selected according to the specific experimental requirements. High-entropy alloy composite materials loaded on carbon paper are prepared by electrodeposition. After deposition, the deposited product is washed and dried to obtain the final product. The prepared sample can be directly subjected to electrochemical testing.

[0012] Specifically, in the precursor solution of step (2), the molar ratio of nickel chloride hexahydrate, anhydrous ferric chloride, cobalt chloride hexahydrate, anhydrous zinc chloride, copper chloride dihydrate, manganese chloride tetrahydrate, and chromium chloride tetrahydrate includes, but is not limited to, 1:5-15:5-15:3:1:1:1.

[0013] Specifically, in step (2), the total concentration of metal chloride salt in the precursor solution can be 0.07-0.35 mol L. -1 More preferably, the total concentration of the metal chloride salt is 0.15-0.25 mol / L. -1 The molar ratio of the metal elements is further optimized to Ni:Fe:Co:Zn:Cu:Mn:Cr=1:5:15:3:1:1:1.

[0014] Specifically, in step (2), the surfactant used can be polymethyl methacrylate (PMMA) or glucose (GLU), and the surfactant concentration in the precursor solution can be 5-10 g / L. -1 For example, the surfactant used can be at a concentration of 5 g / L. -1 Polymethyl methacrylate or 5 g L -1 The volume ratio of N,N-dimethylformamide to acetonitrile can be 3-5:1.

[0015] Specifically, in step (1), the carbon paper is cut into small pieces, soaked in hydrochloric acid, ultrasonically treated, and rinsed with deionized water; ultrasonicated with acetone and rinsed with deionized water; ultrasonicated with deionized water and rinsed with anhydrous ethanol, and then vacuum dried to obtain the carbon paper as a deposition carrier. Further, 0.5 × 1 cm 2 The carbon paper uses 2-4 mol L -1 Soak in hydrochloric acid for 12-36 h, sonicate for 15-45 min, and vacuum dry in a vacuum oven at 40-70℃ for 1-3 h.

[0016] Specifically, in step (3), a carbon paper substrate can be used as the working electrode, a carbon rod as the counter electrode, and a mercury-mercury oxide electrode as the reference electrode; the carbon paper substrate and the carbon rod electrode are placed facing each other, with a distance of 1-2 cm between them. The deposition voltage can be -2 to -3V, and the deposition time can be 1600-2000 s. The preferred loading area is 0.5 cm². 2 .

[0017] This invention provides a high-entropy alloy composite material for metal fuel cells obtained by the above preparation method.

[0018] The present invention also provides the application of the above-mentioned high-entropy alloy composite material for metal fuel cells in hydrogen production by water electrolysis.

[0019] This invention utilizes an electrochemical workstation to perform constant-voltage electrodeposition to load high-entropy alloy materials NiFeCoZnCuMnCr onto the surface of treated carbon paper. The effects of various influencing factors on the properties and morphology of the high-entropy alloy composite material were investigated, and the optimal preparation conditions for the high-entropy alloy composite material were determined. This was achieved by controlling the total concentration of the precursor solution to 0.21 mol / L. -1 A high-entropy alloy composite material with a core-shell structure, consisting of a multimetallic hydroxide (NiFeCoZnCuMnCr)LDH shell and a high-entropy alloy (NiFeCoZnCuMnCr)HEAs core, was synthesized with an optimized Ni:Fe:Co:Zn:Cu:Mn:Cr ratio of 1:5:15:3:1:1:1. This high-entropy alloy composite material achieved an OER and HER of 100 mA cm⁻¹. -2The required overpotentials for the current densities are 378 mV and 331 mV, respectively, demonstrating excellent electrocatalytic performance. Compared with the prior art, the advantages and beneficial effects of this invention are as follows:

[0020] 1) This invention utilizes an electrochemical workstation to perform constant voltage electrodeposition, and investigates the effects of various factors on the performance and morphology of high-entropy alloy catalysts.

[0021] 2) This invention further optimized the synthesis of a high-entropy alloy composite material with a core-shell structure consisting of a multi-metal hydroxide shell and a high-entropy alloy core by adjusting the total concentration of precursors and the proportion of metal salts. As the types and number of components increase, the number of active sites in the high-entropy alloy composite material also increases accordingly, thereby giving the high-entropy alloy composite material excellent OER and HER bifunctional catalytic activity, which can be used for hydrogen production by water electrolysis. Attached Figure Description

[0022] Figure 1 The XRD patterns of the high-entropy alloy composite materials prepared in Examples 1, 2, and 3 are shown below.

[0023] Figure 2 SEM images of catalysts with different total precursor concentrations: (a) Total precursor concentration 0.07 mol L⁻¹; (b) Total precursor concentration 0.21 mol L⁻¹; (c) Total precursor concentration 0.35 mol L⁻¹;

[0024] Figure 3 SEM images of different Fe:Co high-entropy alloy composites: (a) Example 1 Fe:Co=1:3; (b) Example 2 Fe:Co=1:1; (c) Example 3 Fe:Co=3:1;

[0025] Figure 4 TEM image (a) of Fe:Co=1:3 high-entropy alloy composite material in Example 1; high-magnification TEM image (b); (c) SAED image of the outer shell;

[0026] Figure 5 OER (a) and HER LSV (b) curves of high-entropy alloy composites prepared with different additives;

[0027] Figure 6 Electrochemical test results for different materials: (a) OER LSV curve; (b) HER LSV curve; (c) OER Tafel curve; (d) HER Tafel curve; (e) double layer capacitance Cdl; (f) Nyquist plot;

[0028] Figure 7 The it test curve of the Fe:Co=1:3 high-entropy alloy composite material in Example 1;

[0029] Figure 8 The image shows the complete water electrolysis curves of the Fe:Co=1:3 high-entropy alloy composite material before and after the I-T test in Example 1. The inset is a picture of the actual electrolyzed water. Detailed Implementation

[0030] The technical solution of the present invention will be further described in detail below with reference to the embodiments, but the scope of protection of the present invention is not limited thereto.

[0031] In the following examples, all raw materials used are common commercially available products that can be purchased directly or can be prepared using conventional techniques in the art.

[0032] Room temperature refers to 25±℃.

[0033] Example 1

[0034] A method for preparing a high-entropy alloy composite material includes the following steps:

[0035] (1) Cut the carbon paper into 0.5×1 cm pieces. 2 Small pieces, using 3 mol L -1 Soak in hydrochloric acid for 24 h, then sonicate for 30 min, and rinse repeatedly with deionized water 3-5 times after sonication; then sonicate with acetone for 30 min, and rinse repeatedly with deionized water 3-5 times; then sonicate with deionized water for 30 min, rinse repeatedly with anhydrous ethanol 3-5 times, and vacuum dry in a vacuum oven at 60℃ for 2 h to obtain the deposited carrier carbon paper.

[0036] (2) All chemical raw materials can be used directly without any processing. In the preparation of the precursor solution, 20 ml of N,N-dimethylformamide and 5 ml of acetonitrile are measured as solvents, and polymethyl methacrylate is weighed and added as a surfactant (concentration of 5 g / L). -1 Then, nickel chloride hexahydrate, (anhydrous ferric chloride + cobalt chloride hexahydrate), anhydrous zinc chloride, copper chloride dihydrate, manganese chloride tetrahydrate, and chromium chloride tetrahydrate are added in a molar ratio of 1:20:3:1:1:1, with Fe and Co molar ratios of 1:3, and the total concentration of the metal salt is 0.21 mol L. -1 Then, the mixture was magnetically stirred at room temperature for 2 hours to ensure homogeneity, thus obtaining the precursor solution.

[0037] (3) The precursor solution was transferred to an electrolytic cell. A carbon paper substrate was used as the working electrode, a carbon rod as the counter electrode, and a mercury-mercury oxide electrode as the reference electrode. The carbon paper substrate and the carbon rod electrode were placed facing each other with a distance of 1 cm between them for electrodeposition. The deposition voltage was -2.5V, and the deposition time was 1800 s. After deposition, the deposited product was rinsed 3-5 times with deionized water, then rinsed 3-5 times with anhydrous ethanol, and vacuum dried at 60℃ for 2 h to obtain the high-entropy alloy composite material loaded on carbon paper. The prepared sample can be directly subjected to electrochemical testing.

[0038] Example 2

[0039] The preparation process is the same as in Example 1, except that the molar ratio of Fe to Co is 1:1.

[0040] Example 3

[0041] The preparation process is the same as in Example 1, except that the molar ratio of Fe to Co is 3:1.

[0042] Example 4

[0043] The preparation process is the same as in Example 1, except that constant voltage electrodeposition is replaced with pulsed electrodeposition. In pulsed electrodeposition, a specific current is applied for 0.2 s, then the current is turned off for 0.8 s, with one second constituting one cycle. The current density applied in pulsed electrodeposition is 8-64 mA cm⁻¹. -2 .

[0044] Comparative Example 1

[0045] The preparation process is the same as in Example 1, except that the total concentration of the metal salt is 0.07 mol L. -1 .

[0046] Comparative Example 2

[0047] The preparation process is the same as in Example 1, except that the total concentration of the metal salt is 0.35 mol L. -1 .

[0048] Comparative Example 3

[0049] The preparation process is the same as in Example 1, except that polymethyl methacrylate is not added as a surfactant.

[0050] Comparative Example 4

[0051] The preparation process is the same as in Example 1, except that glucose is added as a surfactant.

[0052] Comparative Example 5

[0053] The preparation process is the same as in Example 1, except that manganese chloride tetrahydrate and chromium chloride tetrahydrate are not added, and it is referred to as a pentagonal high-entropy alloy composite material.

[0054] Comparative Example 6

[0055] The preparation process is the same as in Example 1, except that no manganese chloride tetrahydrate, chromium chloride tetrahydrate, or the surfactant polymethyl methacrylate are added. It is referred to as a pentagonal high-entropy alloy composite material with no additives.

[0056] Microstructure and electrochemical performance

[0057] 1. Structural characterization

[0058] The phase composition of high-entropy alloy composites was characterized by XRD, such as... Figure 1 As shown in the figure, it can be seen that the high-entropy alloy composite materials prepared in Examples 1 to 3 do not have obvious alloy diffraction peaks, and their XRD diffraction patterns are the same as those of pure carbon paper (CP). The high-entropy alloy composite materials have an amorphous structure.

[0059] SEM was used to characterize the basic morphological features of high-entropy alloy composites. Figure 2 This is Example 1 (0.21 mol L) -1 (Fe:Co = 1:3), Comparative Example 1 (0.07 mol L) -1 (Fe:Co=1:3) and Comparative Example 2 (0.35 mol L) -1 SEM morphology of Fe:Co = 1:3 (Fe:Co = 1:3). The figure shows that at 0.07 mol L... -1 At the initial concentration, flocculent material formed on the particle surface, but it did not completely cover the particle surface; while at 0.21 mol L... -1 At a certain concentration, densely packed nanosheets formed on the particle surface, completely covering the underlying particles and exhibiting a typical core-shell structure; while at 0.35 mol L... -1 At the specified concentration, the overall particle size was the largest, and no flocculent material appeared on the particle surface, but the catalyst surface appeared to have a thin film of material.

[0060] Figure 3 SEM images of different Fe:Co high-entropy alloy composites from Examples 1 to 3 are presented. The images show that in Example 1 (0.21 mol L... -1 (Fe:Co=1:3) and Example 2 (0.21 mol L) -1 The sample with Fe:Co = 1:1 was granular, while the sample in Example 3 (0.21 mol L) was granular. -1The sample with Fe:Co = 3:1 exhibited a larger sheet-like structure. Flocculent or sheet-like substances appeared on the catalyst surface in all three ratios, but only in Example 1 (0.21 mol L⁻¹) did this phenomenon occur. -1 The surface of the high-entropy alloy composite material (Fe:Co=1:3) is covered with a dense and uniform lamellar structure, forming a core-shell structure. By combining the XRD results with the surface morphology for analysis, it is speculated that the amorphous structure of the high-entropy alloy composite material under the experimental conditions is related to the flocculent or lamellar material appearing on the material surface. Since the flocculent or lamellar material is amorphous, the material also exhibits an amorphous structure.

[0061] TEM was used to further investigate the microstructure of the high-entropy alloy composite material, and its TEM characterization is as follows: Figure 4 As shown in Figure 4(a), Example 1 (0.21 mol L) -1 The Fe:Co=1:3 fraction exhibits a typical lamellar hydrotalcite structure. High-magnification TEM at 4(b) magnification revealed lattice fringes with interplanar spacings of 0.1811 nm and 0.2399 nm, corresponding to the (102) and (101) planes of the Co(OH)2 crystal structure, respectively. However, the lattice fringes are few and indistinct. Figure 4 (c) is the selected electron diffraction pattern (SAED) of this part. The diffraction rings in this part are weak, which is consistent with the small amount and unclear lattice fringes, and also indicates that the crystallinity of this part of the material is weak.

[0062] 2 Electrochemical performance

[0063] OER and HER performance were tested using an electrochemical workstation (Chenhua CHI 760E). A three-electrode system was employed: a high-entropy alloy composite material deposited on carbon paper served as the working electrode; a carbon rod was used as the counter electrode; mercury-mercury oxide was used as the reference electrode; and a 1 mol / L electrolyte was employed. -1 KOH solution. Cyclic voltammetry (CV) activation was performed before linear sweep voltammetry (LSV) testing at a scan rate of 5 mV / s. -1 The voltage range is 0~1 V, with 20 scan cycles. The OER and HER test scan rate is 5 mV / s. -1 CV activation ensures that the catalyst performance remains relatively stable. It is hereby stipulated that the overpotentials for OER and HER mentioned below refer to a current density of 100 mA cm⁻¹. -2 Overpotential at that time.

[0064] To investigate the effect of additives on the properties of high-entropy alloy composites, this invention uses 1 mol L... -1The OER and HER properties of high-entropy alloy composites synthesized with PMMA as an additive, GLU as an additive, and without additives were tested in KOH solution using a three-electrode system. Figure 5 It can be seen that the high-entropy alloy composite material synthesized with PMMA as an additive has the best OER and HER properties, with OER and HER reaching 100 mA cm⁻¹. -2 The overpotentials required for the current densities are 378 mV and 331 mV, respectively. Suitable additives, such as PMMA, can make the catalyst more firmly supported on the carbon paper substrate, enhance the bonding force between the catalyst and the matrix, improve the catalyst's stability, catalytic activity, and electrochemical performance.

[0065] To further demonstrate the excellent OER and HER properties of the seven-element high-entropy alloy composite material, this invention compares the performance of a commercial platinum-carbon catalyst (Pt / C), a five-element high-entropy alloy composite material, and a seven-element high-entropy alloy composite material synthesized by constant voltage and pulse electrodeposition methods. The results are shown in [Figure number missing]. Figure 6 In 1 mol L -1 The OER and HER performance, electrochemical active area, and electrochemical impedance spectroscopy of the materials were tested in KOH solution. The OER and HER polarization curves of each catalyst are shown below. Figure 6 As shown in (a) and (b), the seven-element high-entropy alloy composite material exhibits the best overall catalytic performance, with OER and HER overpotentials of 378 mV and 331 mV, respectively. Figure 6 (c) represents the Tafel slopes of the four catalysts during the OER reaction process. The Tafel slopes are ranked from highest to lowest as follows: pentagonal high-entropy alloy composite + no additives (286.48 mV dec). -1 > Five-element high-entropy alloy composite material (103.26 mV dec) -1 ) > Seven-element high-entropy alloy composite material prepared by pulse electrodeposition (49.98 mV dec) -1 The seven-element high-entropy alloy composite material prepared by constant voltage electrodeposition (45.63 mV dec) -1 ). Figure 6 (d) represents the Tafel slopes of the four catalysts in the HER reaction process, ordered from highest to lowest as follows: Five-element high-entropy alloy composite material + no additives (165.81 mV dec) -1 > Five-element high-entropy alloy composite material (135.52 mV dec) -1 ) > Seven-element high-entropy alloy composite material prepared by pulse electrodeposition (75.53 mV dec) -1 The seven-element high-entropy alloy composite material prepared by constant voltage electrodeposition (48.14 mV dec) -1The seven-element high-entropy alloy composite material prepared by constant-voltage electrodeposition exhibited the lowest Tafel slopes in both the OER and HER reactions, indicating that this catalyst possesses faster reaction kinetics and better catalytic activity. Subsequently, the double-layer capacitance (Cdl) was calculated using CV curves within the non-Radida voltage range. Since the double-layer capacitance (Cdl) is positively correlated with the electrochemically activated area (ECSA), the calculated Cdl allows for comparison of the relative magnitudes of ECSA. The Cdl results for the four high-entropy alloy composite materials are shown below. Figure 6 As shown in (e), the double-layer capacitances of the pentagonal high-entropy alloy composite material with no additives, the heptagonal high-entropy alloy composite material prepared by pulse electrodeposition, the pentagonal high-entropy alloy composite material, and the heptagonal high-entropy alloy composite material prepared by constant voltage electrodeposition are 0.32 mF cm⁻¹. -2 0.45 mF cm -2 23.91 mF cm -2 and 47.93 mF cm -2 The heptagonal high-entropy alloy composite material prepared by constant voltage electrodeposition exhibits the largest double-layer capacitance, corresponding to the largest electrochemically active surface area (ECSA). A larger ECSA in the catalyst results in more exposed active sites during electrocatalysis, leading to better catalytic activity. Therefore, the increased number of active sites is the main reason for the superior performance of the heptagonal high-entropy alloy composite material compared to the pentagonal high-entropy alloy composite material. Electrochemical impedance spectroscopy (EIS) was performed on the four materials, and the test structures are shown below. Figure 6 As shown in (f), the seven-element high-entropy alloy composite materials prepared by constant voltage electrodeposition and pulse electrodeposition have relatively small semi-circular radii of the Nyquist circle. The smaller the radius, the smaller the impedance, the higher the electron transport efficiency, and the faster the reaction rate. The reason why these two materials have small impedance is that the seven-element high-entropy alloy composite material itself has good electrical conductivity.

[0066] To verify the good electrolytic stability of the heptagonal high-entropy alloy composite material, a chronoamperometry (IT) stability test was conducted. Under constant voltage, the longer the discharge time and the smaller the change in current density, the better the catalyst stability. Figure 7 As shown, after constant voltage discharge at 0.75 V for 70 h, the current density retention rate was 89.04%, and the change in current density over time was small, which proves the excellent long-term stability of this high-entropy alloy composite material.

[0067] To demonstrate the superior water electrolysis performance of the heptagonal high-entropy alloy composite material, based on its excellent OER and HER bifunctional catalytic activity, the heptagonal high-entropy alloy composite material was used as both the anode and cathode to perform total water electrolysis for hydrogen and oxygen production under an applied voltage. At 1 mol L... -1Its water-degrading performance was tested in KOH, such as Figure 8 As shown, the current density reaches 50 mA cm⁻¹ at room temperature. -2 At that time, the voltage was 1.784 V, and the actual picture of water electrolysis is shown below. Figure 8 As shown in the built-in illustration, H2 bubbles were generated at the cathode and O2 bubbles at the anode. The overall water splitting performance of the heptagonal high-entropy alloy composite material after stability testing was also assessed. The tested heptagonal high-entropy alloy composite material achieved a water splitting performance of 50 mA cm⁻¹. -2 The required voltage for the current density is 1.851V. After the chronoamperometry stability test, the water electrolysis performance decreased slightly, but the change was not significant, which proves that the seven-element high-entropy alloy composite material has excellent water electrolysis performance.

[0068] In summary, this invention utilizes constant-voltage electrodeposition to prepare a heptagonal high-entropy alloy composite material with excellent OER and HER properties by controlling the total concentration of the precursor solution and the metal salt ratio. Compared to pentagonal high-entropy alloy composites, the heptagonal high-entropy alloy composite material exhibits faster electrochemical reaction kinetics, a larger electrochemical active area, more active sites, and higher conductivity. The heptagonal high-entropy alloy composite material demonstrates good stability, retaining 89.04% of the current density after 70 h of it testing. At 1 mol L... -1 In KOH solution, the total water decomposition curve of the seven-element high-entropy alloy composite material reached 50 mA cm⁻¹. -2 The voltage required for the current density is 1.851 V, which fully demonstrates that the seven-element high-entropy alloy composite material is an excellent catalyst for water electrolysis.

Claims

1. A method for preparing a high-entropy alloy composite material for metal fuel cells, characterized in that, Includes the following steps: 1) Pre-treat the carbon paper; 2) Preparation of precursor solution: Using N,N-dimethylformamide and acetonitrile as solvents, add surfactant and metal chloride salt, mix well to obtain precursor solution; the metal chloride salt is composed of nickel chloride hexahydrate, anhydrous ferric chloride, cobalt chloride hexahydrate, copper chloride dihydrate, anhydrous zinc chloride, manganese chloride tetrahydrate and chromium chloride tetrahydrate. 3) The precursor solution is transferred to the electrolytic cell. A suitable deposition voltage and deposition time are selected. High-entropy alloy composite material loaded on carbon paper is prepared by electrodeposition. After deposition, the deposition product is washed and dried to obtain the final product. In step (2), the surfactant used is polymethyl methacrylate or glucose, and the surfactant concentration in the precursor solution is 5-10 g / L. -1 ; The high-entropy alloy composite material has a core-shell structure with a multi-metal hydroxide (NiFeCoZnCuMnCr) LDH shell and a high-entropy alloy NiFeCoZnCuMnCr HEAs core. The OER and HER of this high-entropy alloy composite material reach 100 mAcm⁻¹. -2 The required overpotentials for the current densities are 378 mV and 331 mV, respectively; In step (2) the precursor solution, the molar ratio of nickel chloride hexahydrate, anhydrous ferric chloride, cobalt chloride hexahydrate, anhydrous zinc chloride, copper chloride dihydrate, manganese chloride tetrahydrate, and chromium chloride tetrahydrate is 1:5-15:5-15:3:1:1:1; In step (2), the total concentration of metal chloride salt in the precursor solution is 0.07-0.35 mol L. -1 .

2. The method for preparing the high-entropy alloy composite material for metal fuel cells as described in claim 1, characterized in that, In step (1), the carbon paper is soaked in hydrochloric acid and then ultrasonically treated, and rinsed with deionized water; acetone is ultrasonically treated and then rinsed with deionized water; deionized water is ultrasonically treated and then rinsed with anhydrous ethanol, and then vacuum dried to obtain the carbon paper as a deposition carrier.

3. The method for preparing high-entropy alloy composite materials for metal fuel cells as described in claim 2, characterized in that, In step (1), the carbon paper is treated with 2-4 mol L... -1 Soak in hydrochloric acid for 12-36 h, sonicate for 15-45 min, and vacuum dry in a vacuum oven at 40-70℃ for 1-3 h.

4. The method for preparing the high-entropy alloy composite material for metal fuel cells as described in claim 1, characterized in that, In step (3), a carbon paper substrate is used as the working electrode, a carbon rod is used as the counter electrode, and a mercury-mercury oxide electrode is used as the reference electrode; the carbon paper substrate and the carbon rod electrode are placed facing each other, with a distance of 1-2 cm between them.

5. The method for preparing the high-entropy alloy composite material for metal fuel cells as described in claim 1, characterized in that, In step (3), the deposition voltage is -2 ~ -3V and the deposition time is 1600-2000 s.

6. A high-entropy alloy composite material for metal fuel cells obtained by any of the preparation methods described in claims 1 to 5.

7. The application of the high-entropy alloy composite material for metal fuel cells as described in claim 6 in hydrogen production by water electrolysis.

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