A high-entropy alloy water electrolysis catalyst and its preparation method

Abstract

This invention provides a high-entropy alloy water electrolysis catalyst and its preparation method. The preparation method includes: mixing, drying, and thermally shocking a metal salt solution, a nitrogen source, and a carbon material to obtain the high-entropy alloy water electrolysis catalyst; the mass ratio of nitrogen to carbon in the nitrogen source is (1-5):20; the high-entropy alloy water electrolysis catalyst includes at least five metal elements. The metal salt in the metal salt solution is reduced to its elemental form under the action of the carbon material, and then thermally shocks the elemental metals together to form an alloy, preventing alloy particle agglomeration, maintaining structural uniformity, and avoiding phase segregation. The carbon material also acts as a support to improve the conductivity of the obtained high-entropy alloy water electrolysis catalyst. Adding a nitrogen source to the carbon material for nitrogen doping modification enhances the interaction between the metal and the support, further improving catalytic activity and stability. The preparation method is simple, quick, and conducive to large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation technology, and relates to an electrolytic water catalyst and its preparation method, particularly to a high-entropy alloy electrolytic water catalyst and its preparation method. Background Technology

[0002] With the rapid development of the global economy, resource consumption is also increasing. The resource and environmental constraints on energy supply have prompted people to actively seek clean, efficient and sustainable alternative energy sources. Hydrogen energy is considered one of the best energy choices for the future due to its advantages of high energy density and zero carbon emissions.

[0003] Electrocatalytic water splitting is one of the most promising green hydrogen production methods, involving a hydrogen evolution reaction (HER) at the cathode and an oxygen evolution reaction (OER) at the anode. Currently, commercial electrocatalytic hydrogen production mainly utilizes the chlor-alkali industry and water-alkali electrolysis processes. In alkaline environments, the HER and OER reactions involve multiple proton coupling and electron transfer processes, resulting in slow reaction kinetics that limit the efficiency of water splitting. CN113584504A discloses a Ru / RuO2 / MoO2 composite material, its preparation method, and its application. (NH4)2MoS4 is added to a RuO2 colloidal suspension, ultrasonically treated, and then hydrazine hydrate is added and stirred until homogeneous. The resulting mixture is maintained at 150-240℃ for 4-48 hours, centrifuged, washed, and dried to obtain the RuO2 / MoS2 composite material. The RuO2 / MoS2 composite material is thoroughly ground until homogeneous, and calcined at 200-1000℃ for 1-12 hours under N2 or an inert atmosphere. After natural cooling to room temperature, the Ru / RuO2 / MoO2 composite material is obtained. This composite material is used as an electrocatalyst for hydrogen evolution, oxygen evolution, or complete water splitting. The Ru / RuO2 / MoO2 composite material obtained by this technical solution has a uniform morphology and excellent electrocatalytic water splitting performance.

[0004] Noble metal catalysts such as Pt, Ru, RuO2, and IrO2 exhibit excellent catalytic activity. However, these catalysts may be oxidized to PtO2, RuO4, and IrO3 in alkaline electrolytes at high potentials, gradually dissolving in the electrolyte and leading to catalyst deactivation. Furthermore, the scarcity and high cost of noble metals further limit their large-scale production and use. Therefore, researchers have made substantial efforts to develop alternative catalysts, one strategy being the use of high-entropy alloy catalysts to improve the electrocatalytic activity of HER / OER.

[0005] High-entropy nanomaterials typically contain five or more elements and possess a homogeneous solid solution structure. This not only provides a vast combinatorial space for exploring new materials but also offers unique microstructures for performance optimization. In catalysis, the binding between reactants or intermediates and the catalyst must be neither too strong nor too weak to achieve optimal catalytic performance. High-entropy alloys, due to the synergistic effect of their multi-element combinations, exhibit a near-continuous distribution of binding energy with reaction intermediates, effectively regulating the interaction between the catalyst and intermediates. Therefore, they show great promise for applications in hydrogen production through water electrolysis.

[0006] CN113774422A discloses a method for preparing a PdCuFeCoNi high-entropy alloy nanoparticle catalyst for water electrolysis, comprising the following steps: mixing and heating five reducing metal salts, namely Pd, Cu, Fe, Co, and Ni, in oleylamine at a safe and controllable temperature; mixing the oleylamine containing a surfactant with the metal salt mixture, which is then ultrasonically dispersed to ensure uniform mixing; protecting and modifying the alloy nanoparticles with the surfactant to prevent agglomeration of the high-entropy alloy nanoparticles; heating and stirring the above mixture to obtain a highly dispersed high-entropy alloy nanoparticle with uniform particle size composed of five metals; cleaning the oleylamine and surfactant on the alloy surface with a mixed washing solution of alcohol and alkane; and loading the high-entropy alloy particles onto a support to obtain its water electrolysis catalyst.

[0007] CN113151856A discloses a method for preparing a high-entropy alloy phosphide nanoparticle catalyst and its application in hydrogen production via water electrolysis. The method employs a hydrothermal approach to prepare the high-entropy nanoparticle catalyst for hydrogen production via water electrolysis. The preparation involves first placing four or more metal sources and a phosphorus source together in oleylamine at a molar ratio of 1:2. A buffer reagent is added, and the mixture is stirred until homogeneous. Under an inert atmosphere, the mixture is heated to 150°C and stirred to react. After the reaction is complete, the mixture is cooled, washed, centrifuged, and dissolved in n-hexane to obtain a high-entropy alloy phosphide nanoparticle solution. The nanoparticle solution is then loaded onto activated carbon via ultrasonic carbon loading and calcined to obtain a carbon-supported high-entropy alloy phosphide nanoparticle catalyst.

[0008] CN114888298A discloses a two-dimensional high-entropy alloy, its preparation method, and its application. The preparation method includes the following steps: (1) dissolving various metal salts in a solvent, then adding an appropriate amount of salt template, and stirring thoroughly to obtain a mixed solution; (2) placing the mixed solution on a heating plate, drying the solvent, and obtaining a precursor powder; (3) placing the precursor powder in a ceramic boat and calcining it at high temperature under a reducing atmosphere; (4) pouring the calcined product into deionized water, soaking it until the salt template is completely dissolved, filtering the solution to obtain a black precipitate, and drying the precipitate to obtain the two-dimensional high-entropy alloy. This technical solution obtains a large-sized two-dimensional layered high-entropy alloy by simply mixing the salt template agent with the metal salt and calcining it at high temperature; and the obtained high-entropy alloy has a large specific surface area, a large number of active sites, and good structural stability, and can be used as an electrocatalyst for water electrolysis.

[0009] Existing high-entropy alloy water electrolysis catalysts suffer from problems such as cumbersome processes, long processing times, poor catalytic activity, demanding preparation conditions, and difficulty in scale-up. To address these issues, this invention provides a high-entropy alloy water electrolysis catalyst and its preparation method, simplifying the preparation process, reducing costs, improving catalytic activity and stability, and facilitating large-scale production. Summary of the Invention

[0010] The purpose of this invention is to provide a high-entropy alloy water electrolysis catalyst and its preparation method, which simplifies the preparation process, shortens the preparation cycle, and improves the catalytic activity and stability of water electrolysis.

[0011] To achieve this objective, the present invention adopts the following technical solution:

[0012] In a first aspect, the present invention provides a method for preparing a high-entropy alloy water electrolysis catalyst, the preparation method comprising the following steps:

[0013] A high-entropy alloy water electrolysis catalyst was obtained by mixing, drying, and thermally shocking metal salt solution, nitrogen source, and carbon material.

[0014] The mass ratio of nitrogen to carbon material in the nitrogen source is (1-5):20;

[0015] The high-entropy alloy water electrolysis catalyst comprises at least five metallic elements.

[0016] In this invention, the metal salt in the metal salt solution is reduced to its elemental form under the action of carbon material. Then, the elemental metals are combined together to form an alloy using a thermal shock method. This process prevents the alloy particles from agglomerating, maintains structural uniformity, and avoids phase segregation. The carbon material also acts as a carrier to improve the conductivity of the resulting high-entropy alloy water electrolysis catalyst. By adding a nitrogen source to modify the carbon material with nitrogen doping, the interaction between the metal and the carrier is enhanced, further improving the catalytic activity and stability. The preparation method is simple, quick, and conducive to large-scale production.

[0017] The mass ratio of nitrogen to carbon in the nitrogen source of this invention is (1-5):20, for example, it can be 1:20, 2:20, 3:20, 4:20 or 5:20, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable. Controlling the mass ratio of nitrogen to carbon in the nitrogen source within the range of (1-5):20 is beneficial for incorporating nitrogen into the support, improving the interaction between the metal and the support, and increasing the reactivity. When the mass ratio of nitrogen to carbon is lower than 1:20, nitrogen cannot modify the metal alloy and the carbon material. When the mass ratio of nitrogen to carbon is higher than 5:20, it will corrode the carbon material and reduce the interaction between the catalyst and the carbon material.

[0018] Preferably, the nitrogen source includes ammonium chloride and / or NH3.

[0019] Preferably, the molar concentration of the metal salt solution is 1.8-2.2 mmol / L, for example, it can be 1.8 mmol / L, 1.9 mmol / L, 2 mmol / L, 2.1 mmol / L or 2.2 mmol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] Preferably, the metal salt in the metal salt solution includes iron salt, nickel salt, cobalt salt, chromium salt, and manganese salt.

[0021] Preferably, the molar fraction of iron in the iron salt relative to the metal element in the metal salt solution is 5-40%, for example, it can be 5%, 10%, 15%, 20%, 25%, 30%, 35% or 40%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] Preferably, the molar fraction of nickel in the nickel salt relative to the metal element in the metal salt solution is 5-40%, for example, it can be 5%, 10%, 15%, 20%, 25%, 30%, 35% or 40%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0023] Preferably, the molar fraction of cobalt in the cobalt salt relative to the metal element in the metal salt solution is 5-40%, for example, it can be 5%, 10%, 15%, 20%, 25%, 30%, 35% or 40%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] Preferably, the sum of the molar fractions of iron and nickel relative to the metal elements in the metal salt solution is 15-65%, for example, it can be 15%, 25%, 35%, 45%, 55% or 65%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] In this invention, the sum of the molar fractions of iron and nickel relative to the metal elements in the metal salt solution is controlled within the range of 15-65%, which is beneficial for providing active sites for the electrocatalytic reaction and improving the activity and stability of the electrocatalytic reaction. When the sum of the molar fractions of iron and nickel is less than 15%, there are insufficient active sites required for the reaction, reducing the reaction activity. When the sum of the molar fractions of iron and nickel is greater than 65%, the influence of other metal elements on the electronic structure of iron and nickel is negligible, resulting in an insignificant high-entropy effect, which also affects the reaction activity and stability.

[0026] Preferably, the molar fraction of chromium in the chromium salt relative to the metal element in the metal salt solution is 5-40%, for example, it can be 5%, 10%, 15%, 20%, 25%, 30%, 35% or 40%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] Preferably, the molar fraction of manganese in the manganese salt relative to the metal element in the metal salt solution is 5-40%, for example, it can be 5%, 10%, 15%, 20%, 25%, 30%, 35% or 40%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] Preferably, the metal salt in the metal salt solution includes any one or a combination of at least two of nitrates, acetates, acetylacetones, or chlorides. Typical but non-limiting combinations include combinations of nitrates and acetates, combinations of acetates and acetylacetones, combinations of acetylacetones and chlorides, or combinations of nitrates, acetates, and acetylacetones.

[0029] Preferably, the temperature of the thermal shock is 700-1100℃, for example, it can be 700℃, 800℃, 900℃, 1000℃ or 1100℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] In this invention, the thermal shock temperature is controlled within the range of 700-1100℃, which helps to ensure the structural uniformity of the obtained high-entropy alloy water electrolysis catalyst, shorten the preparation cycle, simplify the process, and improve catalytic activity and stability. When the thermal shock temperature is below 700℃, there is insufficient heat in the system, and the metal salt cannot be completely reduced to the element to form an alloy, resulting in phase segregation, which leads to reduced catalytic activity and poor stability. When the thermal shock temperature is above 1100℃, the alloy particles are prone to agglomeration, which also affects catalytic activity and stability.

[0031] Preferably, the thermal shock time is 5-20s, for example, it can be 5s, 8s, 10s, 13s, 15s, 18s or 20s, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0032] In this invention, the thermal shock time is controlled within the range of 5-20 seconds, which helps to ensure the structural uniformity of the obtained high-entropy alloy water electrolysis catalyst, shorten the preparation cycle, simplify the process, and improve catalytic activity and stability. When the thermal shock time is less than 5 seconds, the metal salt cannot be completely reduced to the element to form an alloy, resulting in phase segregation, which leads to reduced catalytic activity and poor stability. When the thermal shock time is greater than 20 seconds, the alloy particles are prone to agglomeration, which also affects catalytic activity and stability and is not conducive to the electrocatalytic process.

[0033] Preferably, the relative air pressure of the thermal shock is from -0.05MPa to 0.1MPa, for example, it can be -0.05MPa, -0.03MPa, 0MPa, 0.03MPa, 0.05MPa, 0.08MPa or 0.1MPa, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] Preferably, the thermal shock is performed in a protective atmosphere.

[0035] Preferably, the protective atmosphere includes nitrogen and / or an inert gas.

[0036] Preferably, the inert gas includes any one or a combination of at least two of helium, neon, argon, krypton, or xenon. Typical but non-limiting combinations include a combination of helium and neon, a combination of neon and argon, a combination of argon and krypton, or a combination of krypton and xenon.

[0037] Preferably, the mass ratio of the metal element to the carbon material in the metal salt solution is (1-5):10, for example, it can be 1:10, 2:10, 3:10, 4:10 or 5:10, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0038] Preferably, the solvent for the metal salt solution is a mixture of ethanol and water.

[0039] Preferably, in the ethanol-water mixture, the volume ratio of ethanol to water is (1-4):1, for example, it can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1 or 4:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] Preferably, the drying is accompanied by stirring at a speed of 300-600 r / min, such as 300 r / min, 350 r / min, 400 r / min, 450 r / min, 500 r / min, 550 r / min or 600 r / min, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0041] Preferably, the drying temperature is 60-100℃, for example, it can be 60℃, 70℃, 80℃, 90℃ or 100℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0042] This invention achieves the purpose of drying by stirring to completely evaporate the solvent in the metal salt solution.

[0043] As a preferred embodiment of the preparation method described in the first aspect of the present invention, the preparation method includes:

[0044] After mixing and drying, metal salt solution, nitrogen source and carbon material are subjected to thermal shock for 5-20s in a protective atmosphere at a temperature of 700-1100℃ and a relative pressure of -0.05MPa to 0.1MPa to obtain a high-entropy alloy water electrolysis catalyst.

[0045] The nitrogen source includes ammonium chloride and / or NH3; the mass ratio of nitrogen to carbon material in the nitrogen source is (1-5):20;

[0046] The molar concentration of the metal salt solution is 1.8-2.2 mmol / L; the mass ratio of the metal element to the carbon material in the metal salt solution is (1-5):10;

[0047] The high-entropy alloy water electrolysis catalyst comprises at least five metallic elements.

[0048] In a second aspect, the present invention provides a high-entropy alloy water electrolysis catalyst, wherein the high-entropy alloy water electrolysis catalyst is obtained by the preparation method described in the first aspect.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] In this invention, the metal salt in the metal salt solution is reduced to its elemental form under the action of carbon material. Then, the elemental metals are combined together to form an alloy using a thermal shock method. This process prevents the alloy particles from agglomerating, maintains structural uniformity, and avoids phase segregation. The carbon material also acts as a carrier to improve the conductivity of the resulting high-entropy alloy water electrolysis catalyst. By adding a nitrogen source to modify the carbon material with nitrogen doping, the interaction between the metal and the carrier is enhanced, further improving the catalytic activity and stability. The preparation method is simple, quick, and conducive to large-scale production. Attached Figure Description

[0051] Figure 1 The elemental distribution diagram of the high-entropy alloy water electrolysis catalyst obtained in Example 1 is shown below.

[0052] Figure 2 The high-entropy alloy water electrolysis catalyst obtained in Example 1 was used at 10 mA / cm 2 and 100mA / cm 2 Cyclic stability test results at current density;

[0053] Figure 3 The XRD patterns are comparison diagrams of the bimetallic alloy water electrolysis catalyst obtained in Comparative Example 3, the trimetallic alloy water electrolysis catalyst obtained in Comparative Example 4, the tetrametallic alloy water electrolysis catalyst obtained in Comparative Example 7, and the high-entropy alloy water electrolysis catalyst obtained in Example 1. Detailed Implementation

[0054] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0055] Example 1

[0056] This embodiment provides a method for preparing a high-entropy alloy water electrolysis catalyst, the preparation method comprising:

[0057] A high-entropy alloy water electrolysis catalyst was obtained by mixing a 2 mmol / L metal salt solution, ammonium chloride and carbon material, drying at 70 °C, and then subjecting it to thermal shock in a nitrogen atmosphere for 10 s at a temperature of 800 °C and a relative pressure of 0 MPa.

[0058] The metal salt solution includes five metal salts: ferric chloride, nickel nitrate, cobalt acetate, chromium chloride, and manganese nitrate. The molar fractions of iron, nickel, cobalt, chromium, and manganese relative to the metal elements in the metal salt solution are 20%, 20%, 20%, 20%, and 20%, respectively. The solvent for the metal salt solution is a mixture of ethanol and water with a volume ratio of 4:1.

[0059] The mass ratio of nitrogen to carbon in the ammonium chloride solution is 3:20; the mass ratio of metal to carbon in the metal salt solution is 3:10.

[0060] The drying process is accompanied by stirring at a rate of 600 r / min until the solvent has completely evaporated.

[0061] Example 2

[0062] This embodiment provides a method for preparing a high-entropy alloy water electrolysis catalyst, the preparation method comprising:

[0063] A high-entropy alloy water electrolysis catalyst was obtained by mixing a 1.8 mmol / L metal salt solution, ammonium chloride, and carbon material, drying the mixture at 60 °C, and then subjecting it to a thermal shock in a nitrogen atmosphere at 700 °C and a relative pressure of 0.1 MPa for 20 s.

[0064] The metal salt solution comprises five metal salts: ferric acetate, nickel chloride, cobalt acetylacetonate, chromium nitrate, and manganese chloride. The molar fractions of iron, nickel, cobalt, chromium, and manganese relative to the metal elements in the metal salt solution are 5%, 40%, 10%, 10%, and 35%, respectively, meaning the sum of the molar fractions of iron and nickel is 45%. The solvent for the metal salt solution is a mixture of ethanol and water with a volume ratio of 3:1.

[0065] The mass ratio of nitrogen to carbon in the nitrogen source is 1:20; the mass ratio of metal to carbon in the metal salt solution is 1:10.

[0066] The drying process is accompanied by stirring at a rate of 500 r / min until the solvent has completely evaporated.

[0067] Example 3

[0068] This embodiment provides a method for preparing a high-entropy alloy water electrolysis catalyst, the preparation method comprising:

[0069] A high-entropy alloy water electrolysis catalyst was obtained by mixing a 2.2 mmol / L metal salt solution, ammonium chloride, and carbon material, drying the mixture at 80 °C, and then subjecting it to a thermal shock in a nitrogen atmosphere at 1100 °C and a relative pressure of -0.05 MPa for 5 s.

[0070] The metal salt solution comprises five metal salts: ferric nitrate, nickel acetate, cobalt nitrate, chromium nitrate, and manganese chloride. The molar fractions of iron, nickel, cobalt, chromium, and manganese relative to the metal elements in the metal salt solution are 40%, 5%, 5%, 40%, and 10%, respectively, meaning the sum of the molar fractions of iron and nickel is 45%. The solvent for the metal salt solution is a 1:1 volume ratio mixture of ethanol and water.

[0071] The mass ratio of nitrogen to carbon in the nitrogen source is 5:20; the mass ratio of metal to carbon in the metal salt solution is 5:10.

[0072] The drying process is accompanied by stirring at a rate of 300 r / min until the solvent has completely evaporated.

[0073] Example 4

[0074] This embodiment provides a method for preparing a high-entropy alloy electrolytic water catalyst. Except for the thermal shock temperature of 600°C, the preparation method is the same as in Example 1.

[0075] Example 5

[0076] This embodiment provides a method for preparing a high-entropy alloy water electrolysis catalyst. Except for the thermal shock temperature of 1200℃, the preparation method is the same as in Example 1.

[0077] Example 6

[0078] This embodiment provides a method for preparing a high-entropy alloy water electrolysis catalyst. In this method, except for the thermal shock time of 3 seconds, everything else is the same as in Example 1.

[0079] Example 7

[0080] This embodiment provides a method for preparing a high-entropy alloy electrolytic water catalyst. In this method, except for the thermal shock time of 5 seconds, everything else is the same as in Example 1.

[0081] Example 8

[0082] This embodiment provides a method for preparing a high-entropy alloy water electrolysis catalyst. Except for the thermal shock time of 20s, the preparation method is the same as in Example 1.

[0083] Example 9

[0084] This embodiment provides a method for preparing a high-entropy alloy electrolytic water catalyst. Except for the thermal shock time of 25s, the preparation method is the same as in Example 1.

[0085] Example 10

[0086] This embodiment provides a method for preparing a high-entropy alloy water electrolysis catalyst. In this method, except that the molar fractions of iron, nickel, cobalt, chromium and manganese in the metal salt solution relative to the metal elements in the metal salt solution are 4 / 11, 4 / 11, 1 / 11, 1 / 11 and 1 / 11 respectively, that is, the sum of the molar fractions of iron and nickel is 8 / 11, the rest are the same as in Example 1.

[0087] Example 11

[0088] This embodiment provides a method for preparing a high-entropy alloy water electrolysis catalyst. In this method, except that the molar fractions of iron, nickel, cobalt, chromium and manganese in the metal salt solution relative to the metal elements in the metal salt solution are 1 / 14, 1 / 14, 4 / 14, 4 / 14 and 4 / 14 respectively, i.e. the sum of the molar fractions of iron and nickel is 1 / 7, the rest are the same as in Example 1.

[0089] Example 12

[0090] This embodiment provides a method for preparing a high-entropy alloy water electrolysis catalyst. In this method, except that the molar fractions of iron, nickel, cobalt, chromium and manganese in the metal salt solution relative to the metal elements in the metal salt solution are 3 / 13, 3 / 13, 3 / 13, 2 / 13 and 2 / 13 respectively, i.e. the sum of the molar fractions of iron and nickel is 6 / 13, the rest are the same as in Example 1.

[0091] Comparative Example 1

[0092] This comparative example provides a method for preparing a high-entropy alloy water electrolysis catalyst. In this method, except that the mass ratio of nitrogen to carbon in ammonium chloride is 1:30, everything else is the same as in Example 1.

[0093] Comparative Example 2

[0094] This comparative example provides a method for preparing a high-entropy alloy water electrolysis catalyst. In this method, except that the mass ratio of nitrogen to carbon in ammonium chloride is 6:20, all other aspects are the same as in Example 1.

[0095] Comparative Example 3

[0096] This comparative example provides a method for preparing a bimetallic alloy water electrolysis catalyst. In this method, except that the metal salt solution contains only ferric chloride and nickel nitrate, and the molar fractions of iron and nickel relative to the metal elements in the metal salt solution are 50% and 50%, respectively, the rest is the same as in Example 1, and a bimetallic alloy water electrolysis catalyst is obtained.

[0097] Comparative Example 4

[0098] This comparative example provides a method for preparing a trimetallic alloy water electrolysis catalyst. In this method, except that the metal salt solution contains ferric chloride, nickel nitrate, and manganese nitrate, and the molar fractions of iron, nickel, and manganese relative to the metal elements in the metal salt solution are 1 / 3, 1 / 3, and 1 / 3, respectively, the rest is the same as in Example 1, and a trimetallic alloy water electrolysis catalyst is obtained.

[0099] Comparative Example 5

[0100] This comparative example provides a method for preparing a trimetallic alloy water electrolysis catalyst. In this method, except that the metal salt solution contains ferric chloride, nickel nitrate and cobalt acetate, and the molar fractions of iron, nickel and cobalt elements relative to the metal elements in the metal salt solution are 1 / 3, 1 / 3 and 1 / 3 respectively, the rest are the same as in Example 1, and a trimetallic alloy water electrolysis catalyst is obtained.

[0101] Comparative Example 6

[0102] This comparative example provides a method for preparing a trimetallic alloy water electrolysis catalyst. In this method, except that the metal salt solution contains ferric chloride, nickel nitrate and chromium chloride, and the molar fractions of iron, nickel and chromium elements relative to the metal elements in the metal salt solution are 1 / 3, 1 / 3 and 1 / 3 respectively, the rest are the same as in Example 1, and a trimetallic alloy water electrolysis catalyst is obtained.

[0103] Comparative Example 7

[0104] This comparative example provides a method for preparing a four-metal alloy water electrolysis catalyst. In this method, except that the metal salt solution contains ferric chloride, nickel nitrate, cobalt acetate and manganese nitrate, and the molar fractions of iron, nickel, cobalt and manganese elements relative to the metal elements in the metal salt solution are 25%, 25%, 25% and 25% respectively, the rest are the same as in Example 1, and a four-metal alloy water electrolysis catalyst is obtained.

[0105] Comparative Example 8

[0106] This comparative example provides a method for preparing a four-metal alloy water electrolysis catalyst. In this method, except that the metal salt solution contains ferric chloride, nickel nitrate, chromium chloride and manganese nitrate, and the molar fractions of iron, nickel, chromium and manganese elements relative to the metal elements in the metal salt solution are 25%, 25%, 25% and 25% respectively, the rest are the same as in Example 1, and a four-metal alloy water electrolysis catalyst is obtained.

[0107] Comparative Example 9

[0108] This comparative example provides a method for preparing a four-metal alloy water electrolysis catalyst. In this method, except that the metal salt solution contains ferric chloride, nickel nitrate, cobalt acetate and chromium chloride, and the molar fractions of iron, nickel, cobalt and chromium elements relative to the metal elements in the metal salt solution are 25%, 25%, 25% and 25% respectively, the rest are the same as in Example 1, and a four-metal alloy water electrolysis catalyst is obtained.

[0109] Comparative Example 10

[0110] This comparative example provides a commercial iridium oxide catalyst (IrO2) sourced from CAS Innovation.

[0111] Performance testing

[0112] The performance of the high-entropy alloy water electrolysis catalysts obtained in Examples 1-12 and Comparative Examples 1-2, the bimetallic alloy water electrolysis catalyst obtained in Comparative Example 3, the trimetallic alloy water electrolysis catalysts obtained in Comparative Examples 4-6, the tetrametallic alloy water electrolysis catalysts obtained in Comparative Examples 7-9, and the commercial iridium oxide catalyst provided in Comparative Example 10 were tested, and their performance at 10 mA / cm² was measured. 2 The overpotential at time and the decay rate after 100 hours of cycling were determined using the following specific test methods:

[0113] Take 5 mg of each of the following: the high-entropy alloy water electrolysis catalysts obtained in Examples 1-12 and Comparative Examples 1-2; the bimetallic alloy water electrolysis catalyst obtained in Comparative Example 3; the trimetallic alloy water electrolysis catalyst obtained in Comparative Examples 4-6; the tetrametallic alloy water electrolysis catalyst obtained in Comparative Examples 7-9; and the commercial iridium oxide catalyst provided in Comparative Example 10. Add these to a mixed solution containing 450 μL of ethanol and 50 μL of 5% Nafion. After ultrasonic mixing, add the solution dropwise to a volume of 0.25 cm. 2 On hydrophilic carbon paper, the loading of Ir in Comparative Example 10 was 0.2 mg / cm³. 2 Electrochemical and stability tests were conducted after the solvent had completely evaporated at room temperature. The electrochemical testing system was a three-electrode system, with a platinum sheet as the counter electrode, carbon paper as the working electrode, mercury / mercury oxide as the reference electrode, and a 1M KOH solution as the electrolyte.

[0114] The current density was tested to reach 10 mA / cm². 2 Overpotential at time (mV@10mA / cm) 2 ), and at a current density of 10 mA / cm 2 Constant current stability tests were conducted, and the decay rate (%) after 100 hours of cycling was measured. The results are shown in Table 1.

[0115] Table 1

[0116]

[0117]

[0118] As can be seen from Examples 1-3, the high-entropy alloy water electrolysis catalyst obtained in this invention exhibits performance at 10 mA / cm². 2 The overpotential can be as low as 254mV@10mA / cm 2 The decay rate after 100 hours of cycling was only 0.5%, indicating good catalytic performance and stability. Figure 1 The elemental distribution diagram of the high-entropy alloy water electrolysis catalyst obtained in Example 1 shows that the particle size distribution of the obtained high-entropy alloy water electrolysis catalyst is relatively narrow, with a particle size of about 25 nm, and each metal is uniformly distributed on the alloy particles, proving that the high-entropy alloy water electrolysis catalyst was successfully synthesized. Figure 2The high-entropy alloy water electrolysis catalyst obtained in Example 1 was used at 10 mA / cm 2 and 100mA / cm 2 The cyclic stability test graph at current density shows that the high-entropy alloy water electrolysis catalyst obtained in Example 1 maintains stable performance at 10 mA / cm². 2 and 100mA / cm 2 The synthesized high-entropy alloy water electrolysis catalyst can operate stably for more than 100 hours under various current densities, indicating that it has good stability.

[0119] A comparison of Examples 4 and 5 with Example 1 shows that controlling the thermal shock temperature within the range of 700-1100℃ in this invention helps ensure the structural uniformity of the obtained high-entropy alloy water electrolysis catalyst, shortens the preparation cycle, simplifies the process, and improves catalytic activity and stability. When the thermal shock temperature is below 700℃, there is insufficient heat in the system, and the metal salt cannot be completely reduced to its elemental form to form an alloy, resulting in phase segregation, which leads to reduced catalytic activity and poor stability. When the thermal shock temperature is above 1100℃, the alloy particles are prone to agglomeration, which also affects catalytic activity and stability.

[0120] A comparison of Examples 6 and 7 with Example 1 shows that as the thermal shock time decreases, the overpotential of the obtained high-entropy alloy water electrolysis catalyst increases and the decay rate increases. This is because the metal salt cannot be completely reduced to the element to form an alloy, resulting in phase segregation, which leads to a decrease in catalytic activity and a deterioration in stability. A comparison of Examples 8 and 9 with Example 1 shows that when the thermal shock time is higher than 20 seconds, the alloy particles are prone to agglomeration, which also affects the catalytic activity and stability, and is not conducive to the electrocatalytic process.

[0121] A comparison of Examples 10-12 with Example 1 shows that controlling the sum of the molar fractions of iron and nickel relative to the metal elements in the metal salt solution within the range of 15-65% is beneficial for providing active sites for the electrocatalytic reaction, thereby improving the activity and stability of the electrocatalytic reaction. When the sum of the molar fractions of iron and nickel is less than 15%, there are insufficient active sites required for the reaction, reducing the reaction activity. When the sum of the molar fractions of iron and nickel is greater than 65%, the influence of other metal elements on the electronic structure of iron and nickel is minimal, resulting in an insignificant high-entropy effect, which also affects the reaction activity and stability.

[0122] Comparison of Comparative Examples 1 and 2 with Example 1 shows that controlling the mass ratio of nitrogen to carbon material in the nitrogen source within the range of (1-5):20 is beneficial for incorporating nitrogen into the support, improving the interaction between the metal and the support, and enhancing the reactivity.

[0123] Comparative Examples 3, 4-6, and 7-9 obtained bimetallic alloy water electrolysis catalysts, trimetallic alloy water electrolysis catalysts, and tetrametallic alloy water electrolysis catalysts by adding two, three, and four metals, respectively. The comparison between Comparative Examples 3-9 and Example 1 shows that the synergistic effect of multi-element mixing in high-entropy alloys can effectively improve the catalytic activity and stability of the catalyst.

[0124] Figure 3 The XRD comparison diagrams of the bimetallic alloy water electrolysis catalyst obtained in Comparative Example 3, the trimetallic alloy water electrolysis catalyst obtained in Comparative Example 4, the tetrametallic alloy water electrolysis catalyst obtained in Comparative Example 7, and the high-entropy alloy water electrolysis catalyst obtained in Example 1 show that the multimetallic alloy catalyst has a single-phase face-centered cubic (FCC) lattice structure and has higher OER activity.

[0125] Comparative Example 10 is a commercial iridium oxide catalyst, whose catalytic activity and stability are also lower than the high-entropy alloy water electrolysis catalyst provided in this invention.

[0126] In summary, this invention provides a high-entropy alloy water electrolysis catalyst and its preparation method. The metal salt in the metal salt solution is reduced to its elemental form under the action of carbon material. Then, thermal shock is used to bond the elemental metals together to form an alloy, preventing alloy particle agglomeration, maintaining structural uniformity, and avoiding phase segregation. The carbon material also acts as a support to improve the conductivity of the resulting high-entropy alloy water electrolysis catalyst. Nitrogen doping modification of the carbon material by adding a nitrogen source enhances the interaction between the metal and the support, further improving catalytic activity and stability. The preparation method is simple, quick, and conducive to large-scale production.

[0127] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a high-entropy alloy water electrolysis catalyst, characterized in that, The preparation method includes the following steps: A high-entropy alloy water electrolysis catalyst was obtained by mixing, drying, and thermally shocking metal salt solution, nitrogen source, and carbon material. The mass ratio of nitrogen to carbon material in the nitrogen source is (1-5):20; The high-entropy alloy water electrolysis catalyst is composed of five metallic elements; The nitrogen source is ammonium chloride; The temperature of the thermal shock is 700-1100℃; The duration of the thermal shock is 10-20 seconds; The metal salts in the metal salt solution are iron salts, nickel salts, cobalt salts, chromium salts, and manganese salts; The molar concentration of the metal salt solution is 1.8-2.2 mmol / L; The molar fraction of iron in the iron salt relative to the metal element in the metal salt solution is 5-40%. The nickel salt contains 5-40% nickel relative to the metal element in the metal salt solution. The sum of the molar fractions of iron and nickel relative to the metal elements in the metal salt solution is 15-65%. The thermal shock was conducted in a protective atmosphere; The mass ratio of metal elements to carbon materials in the metal salt solution is (1-5):

10.

2. The preparation method of the high-entropy alloy water electrolysis catalyst according to claim 1, characterized in that, The molar fraction of cobalt in the cobalt salt relative to the metal elements in the metal salt solution is 5-40%.

3. The preparation method of the high-entropy alloy water electrolysis catalyst according to claim 1, characterized in that, The molar fraction of chromium in the chromium salt relative to the metal element in the metal salt solution is 5-40%.

4. The preparation method of the high-entropy alloy water electrolysis catalyst according to claim 1, characterized in that, The molar fraction of manganese in the manganese salt relative to the metal elements in the metal salt solution is 5-40%.

5. The preparation method of the high-entropy alloy water electrolysis catalyst according to claim 1, characterized in that, The relative pressure of the thermal shock is -0.05 MPa to 0.1 MPa.

6. The preparation method of the high-entropy alloy water electrolysis catalyst according to claim 1, characterized in that, The protective atmosphere includes nitrogen and / or an inert gas.

7. The preparation method of the high-entropy alloy water electrolysis catalyst according to claim 6, characterized in that, The inert gas includes any one or a combination of at least two of helium, neon, argon, krypton, or xenon.

8. The preparation method of the high-entropy alloy water electrolysis catalyst according to claim 1, characterized in that, The metal salt in the metal salt solution includes any one or a combination of at least two of nitrates, acetates, acetylacetones, or chlorides.

9. The preparation method of the high-entropy alloy water electrolysis catalyst according to claim 1, characterized in that, The solvent for the metal salt solution is a mixture of ethanol and water.

10. The method for preparing the high-entropy alloy water electrolysis catalyst according to claim 9, characterized in that, In the ethanol-water mixture, the volume ratio of ethanol to water is (1-4):

1.

11. The preparation method of the high-entropy alloy water electrolysis catalyst according to claim 1, characterized in that, The drying process is accompanied by stirring at a speed of 300-600 r / min.

12. The preparation method of the high-entropy alloy water electrolysis catalyst according to claim 1, characterized in that, The drying temperature is 60-100℃.

13. The preparation method of the high-entropy alloy water electrolysis catalyst according to claim 10, characterized in that, The preparation method includes: After mixing and drying, metal salt solution, nitrogen source and carbon material are subjected to thermal shock for 10-20s in a protective atmosphere at a temperature of 700-1100℃ and a relative pressure of -0.05MPa to 0.1MPa to obtain a high-entropy alloy water electrolysis catalyst. The nitrogen source is ammonium chloride; the mass ratio of nitrogen to carbon in the nitrogen source is (1-5):20; The molar concentration of the metal salt solution is 1.8-2.2 mmol / L; the mass ratio of the metal element to the carbon material in the metal salt solution is (1-5):10; The high-entropy alloy water electrolysis catalyst is composed of five metallic elements.

14. A high-entropy alloy water electrolysis catalyst, characterized in that, The high-entropy alloy water electrolysis catalyst is obtained by the preparation method according to any one of claims 1-13.

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