A high-entropy alloy catalyst, its preparation method and application

Abstract

The present invention provides a high entropy alloy catalyst and a preparation method and application thereof, wherein the preparation method comprises: mixing a carbon material and a metal salt solution to obtain a mixture; drying, grinding and thermally shocking the mixture to obtain the high entropy alloy catalyst; the temperature of the thermal shock is 700-1000°C; and the time of the thermal shock is 8-40s. The present invention utilizes a thermal shock method to prepare a high entropy alloy catalyst, and the whole process time is less than 1 minute, which can effectively prevent alloy particles from agglomerating, and maximize the structural uniformity of the high entropy alloy catalyst to avoid phase segregation; during the thermal shock process, the carbon material can act as a carrier to improve the conductivity of the high entropy alloy catalyst, and also acts as a reducing agent to reduce the metal salt to a metal element, and the metal element diffuses at a high temperature to form an alloy, and finally generates a high entropy alloy catalyst; the process is simple, easy to control, and the process is short, which is conducive to realizing the large-scale production of the high entropy alloy catalyst.

Description

Technical Field

[0001] The present invention belongs to the field of catalysts, and relates to an alloy catalyst and its preparation method and application, and particularly relates to a high-entropy alloy catalyst and its preparation method and application. Background Art

[0002] As the most ideal new energy in the 21st century, hydrogen energy has the advantages of being clean, renewable, and rich in resources. It is regarded as a new generation of energy that can replace fossil fuels and is the development direction of human strategic energy. The electrolytic water hydrogen production technology uses renewable resources such as solar energy, has a simple process and no pollution, and is one of the best ways for large-scale hydrogen production. In the actual electrolytic water hydrogen production process, due to the sluggish four-electron reaction kinetics process of the oxygen evolution reaction, its overpotential is relatively high, and the industrial energy consumption of water electrolysis is relatively large. Therefore, it is of great significance to prepare an oxygen evolution electrode with high catalytic activity and high stability, reduce the oxygen evolution overpotential in the process of water electrolysis, and thus reduce the energy consumption of electrolytic water hydrogen production.

[0003] CN113235108A discloses a MXene-supported noble metal cluster catalyst and its preparation method and application. In the MXene-supported noble metal cluster catalyst, the noble metal is supported on MXene in the form of clusters. The noble metal includes platinum, iridium, ruthenium, or rhodium, and the MXene is in the form of paper clusters. This technical solution sprays a mixed solution of MXene and noble metal salts into a three-dimensional paper cluster structure of MXene-supported noble metal clusters by spray drying. Preparing noble metals such as Pt / Ru / Ir / Rh into clusters can improve their catalytic efficiency, and loading the clusters on MXene can improve their stability and activity. This series of materials has excellent electrocatalytic performance and can be used as active materials for electrolytic water hydrogen production.

[0004] CN108179433A discloses an ordered mesoporous carbon-supported nano-iridium-based electrocatalytic hydrogen evolution electrode and its preparation and application. This catalytic system uses three-dimensional porous nickel foam as the electrode substrate, ordered mesoporous carbon as the carrier, and nano-scale noble metal iridium as the active component. The mass content of the noble metal iridium in the catalyst is 0.6%, and the mass loading in the whole electrode is 0.3 mg / cm 2 . In an alkaline medium, it can efficiently electrolyze water to produce hydrogen and show good stability, giving full play to the role of noble metals. Its preparation process involves loading the catalyst on the nickel foam electrode by in-situ carbonization method, without the need for an external binder, and the process is mature, stable, simple to operate, and highly controllable. The most effective current electrolytic water oxygen evolution catalysts are still noble metal catalysts such as ruthenium and iridium, but their reserves are low, prices are high, and they are difficult to operate stably continuously in long-term high-power electrolysis, and cannot be popularized for industrial applications. Therefore, studying inexpensive, highly efficient and stable catalysts has become the key to promoting the development of electrolytic water technology and hydrogen energy economy.

[0005] In recent years, due to the properties of high-entropy nanomaterials having a multi-element composition (usually five or more elements) and a homogeneous solid-solution structure, they can effectively regulate the interaction between the catalyst and reaction intermediates. The atomic diffusion retardation effect caused by their configurational entropy enables high-entropy nanocatalysts to operate for a long time in harsh environments, thereby enhancing the stability of the catalyst.

[0006] CN115125427A discloses a method for developing a wear-resistant CoCrFeNiAlx system high-entropy alloy. Powders of Co, Cr, Fe, Ni, and Al are selected in proportion, subjected to impurity and grinding refinement treatments, and the uniformly mixed powders are placed in a copper crucible in a furnace and vacuum melted using arc heating until fully melted. The CoCrFeNiAlx system high-entropy alloy prepared by arc heating has high hardness and wear resistance.

[0007] CN105861909 discloses a FeSiBAlNiCo bulk high-entropy alloy prepared by powder metallurgy. For the FeSiBAlNiCo bulk high-entropy alloy of the present invention, the molar ratio of Fe, Si, B, Al, Ni, and Co is 1:1:1:1:1:(0-1); its crystal structure includes face-centered cubic (FCC), body-centered cubic (BCC), two-phase intermetallic compounds FeSi and FeB. Medium-sized Co elements are added to the Fe-Si-B-Al-Ni quinary alloy, and a bulk high-entropy alloy with a diameter of 15 mm is prepared using spark plasma sintering technology. The high-entropy alloy has a relative density of more than 96.5% and a hardness value of more than 1100 HV, and has outstanding corrosion resistance in NaCl solution, meeting the special requirements of certain harsh environments.

[0008] However, high-entropy alloys prepared by traditional processes such as vacuum melting and powder metallurgy are often bulk materials, which are difficult to apply in fields such as catalysis, energy, and environment. Moreover, the preparation process is relatively complex and the cost is high. How to achieve the nano-scale and batch production of high-entropy materials, and ensure that the synthesized high-entropy materials are evenly distributed without phase separation is the current research focus. In this regard, the present invention uses the method of high-temperature thermal shock to provide a high-entropy alloy catalyst and its preparation method and application, solving the problem of particle agglomeration during the extremely rapid heating and cooling processes and improving the catalytic performance of water electrolysis. Summary of the Invention

[0009] The purpose of the present invention is to provide a high-entropy alloy catalyst and its preparation method and application, reducing the particle agglomeration phenomenon during the preparation of high-entropy alloys, shortening the preparation cycle, and realizing the nano-scale and batch production of high-entropy alloys.

[0010] To achieve the purpose of this invention, the following technical solutions are adopted:

[0011] In a first aspect, the present invention provides a method for preparing a high entropy alloy catalyst, the preparation method comprising:

[0012] The carbon material and the metal salt solution are mixed to obtain a mixture; the mixture is dried, ground and thermally shocked to obtain the high entropy alloy catalyst;

[0013] The temperature of the thermal shock is 700-1000°C;

[0014] The time of the thermal shock is 8-40s.

[0015] The present invention utilizes a thermal shock method to prepare a high entropy alloy catalyst. The entire process takes less than 1 minute, which can effectively prevent alloy particle agglomeration. Combined with the characteristics of rapid cooling, the structural uniformity of the high entropy alloy catalyst can be maintained to the maximum extent, avoiding phase segregation. During the thermal shock process, the carbon material can serve as a carrier to improve the conductivity of the high entropy alloy catalyst and also act as a reducing agent, which can effectively reduce the metal salt to a metal element. The metal element diffuses at a high temperature to form an alloy, and finally generates a high entropy alloy catalyst.

[0016] The temperature of the thermal shock is 700-1000°C, for example, it can be 700°C, 750°C, 800°C, 850°C, 900°C, 950°C or 1000°C, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable. When the temperature is lower than 700°C, the thermal shock temperature is too low to reduce the metal salt to a single substance and eventually form an alloy, resulting in phase segregation of the material, which reduces the activity and stability of the high entropy alloy catalyst; when the temperature is higher than 1000°C, it is easy to cause the high entropy alloy catalyst particles to agglomerate, which is not conducive to the catalytic reaction. Therefore, the temperature of the thermal shock is controlled within the range of 700-1000°C, which is conducive to preventing the alloy particles from agglomerating, maintaining the structural uniformity of the high entropy alloy catalyst, and avoiding phase segregation.

[0017] The time of the thermal shock is 8-40s, for example, it can be 8s, 10s, 15s, 20s, 25s, 30s, 35s or 40s, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable. When the time is less than 8s, the thermal shock time is too short to reduce the metal salt and eventually form a high entropy alloy catalyst, resulting in phase segregation of the material; when the time is more than 40s, it is easy to cause the alloy particles to agglomerate. Therefore, the time of the thermal shock is controlled within the range of 8-40s, which is conducive to preventing the alloy particles from agglomerating, and maintaining the structural uniformity of the high entropy alloy catalyst to avoid phase segregation.

[0018] Preferably, the thermal shock is performed in a protective atmosphere.

[0019] Preferably, the protective atmosphere includes nitrogen and / or inert gas.

[0020] 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 the combination of helium and neon, the combination of neon and argon, the combination of argon and krypton, the combination of krypton and xenon, or the combination of helium, neon and argon.

[0021] Preferably, the relative pressure of the thermal shock is -0.05 to 0.1 Mpa. For example, it can be -0.05 MPa, -0.04 MPa, -0.03 MPa, -0.02 MPa, -0.01 MPa, 0 MPa, 0.05 MPa or 0.1 MPa, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0022] The solid-liquid ratio of the carbon material to the metal salt solution is (0.3 - 4):1. For example, it can be 0.3:1, 0.5:1, 1:1, 2:1, 3:1 or 4:1, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable. The unit of the solid-liquid ratio is g / L.

[0023] Preferably, the mass ratio of the metal element in the metal salt solution to the carbon material is (5 - 25):100. For example, it can be 5:100, 8:100, 10:100, 13:100, 15:100, 18:100, 20:100, 23:100 or 25:100, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0024] The mass ratio of the metal element in the metal salt solution of the present invention to the carbon material is (5 - 25):100, which is beneficial to providing abundant active sites for the catalytic reaction and ensuring the dispersion of the metal. When the mass ratio is lower than 5:100, the metal element is too low, resulting in insufficient active sites in the catalyst and an increase in the diffusion distance of metal atoms, which is not conducive to the formation of alloys. When the mass ratio is higher than 25:100, when the metal content is too high, the formed alloy particles are prone to agglomeration, leading to a decrease in catalytic performance.

[0025] The carbon material includes carbon black XC-72.

[0026] Preferably, the metal salt in the metal salt solution includes any one or a combination of at least two of transition metal salts, rare earth metal salts, magnesium salts, indium salts or gallium salts. Typical but non-limiting combinations include combinations of transition metal salts and rare earth metal salts, rare earth metal salts and magnesium salts, magnesium salts and indium salts, indium salts and gallium salts, combinations of transition metal salts, rare earth metal salts and magnesium salts, combinations of transition metal salts, rare earth metal salts, magnesium salts and indium salts, or combinations of transition metal salts, rare earth metal salts, magnesium salts, indium salts and gallium salts.

[0027] Preferably, the transition metal salt includes any one or a combination of at least two of iron salts, nickel salts, cobalt salts, copper salts, manganese salts or zinc salts. Typical but non-limiting combinations include combinations of iron salts and nickel salts, nickel salts and cobalt salts, copper salts and manganese salts, manganese salts and zinc salts, combinations of iron salts, nickel salts and cobalt salts, combinations of iron salts, nickel salts, cobalt salts and copper salts, combinations of iron salts, nickel salts, cobalt salts, copper salts and manganese salts, or combinations of iron salts, nickel salts, cobalt salts, copper salts, manganese salts and zinc salts.

[0028] Preferably, the rare earth metal salt includes any one or a combination of at least two of samarium salts, gadolinium salts, yttrium salts or scandium salts. Typical but non-limiting combinations include combinations of samarium salts and gadolinium salts, gadolinium salts and yttrium salts, yttrium salts and scandium salts, combinations of samarium salts, gadolinium salts and yttrium salts, or combinations of samarium salts, gadolinium salts, yttrium salts and scandium salts.

[0029] Preferably, the molar concentration of the metal salt solution is 0.005 - 0.1 mol / mL. For example, it can be 0.005 mol / mL, 0.01 mol / mL, 0.02 mol / mL, 0.03 mol / mL, 0.04 mol / mL, 0.05 mol / mL, 0.06 mol / mL, 0.07 mol / mL, 0.08 mol / mL, 0.09 mol / mL or 0.1 mol / mL, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0030] Preferably, the metal salt solution includes at least 5 metal elements. For example, it can be 5, 6, 7, 8 or 9, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0031] Preferably, the molar fraction of any one metal element in the metal salt solution relative to the contained metal elements 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 this numerical range are equally applicable.

[0032] Preferably, the metal salt in the metal salt solution includes any one or a combination of at least two of nitrate, acetate, acetylacetonate or chloride. Typical but non-limiting combinations include the combination of nitrate and acetate, the combination of acetate and acetylacetonate, the combination of acetylacetonate and chloride, the combination of nitrate, acetate and acetylacetonate, the combination of acetate, acetylacetonate and chloride, or the combination of nitrate, acetate, acetylacetonate and chloride.

[0033] Preferably, the solvent of the metal salt solution is a mixture of ethanol and water.

[0034] Preferably, in the ethanol and 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 this numerical range are equally applicable.

[0035] The temperature of the mixing is 20 - 30 °C. For example, it can be 20 °C, 22 °C, 24 °C, 26 °C, 28 °C or 30 °C, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0036] Preferably, the mixing time is 20 - 28 h. For example, it can be 20 h, 21 h, 22 h, 23 h, 24 h, 25 h, 26 h, 27 h or 28 h, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0037] Preferably, the mixing is accompanied by stirring, and the stirring rate is 300 - 600 r / min. For example, it can be 300 r / min, 350 r / min, 400 r / min, 450 r / min, 500 r / min, 550 r / min or 600 r / min, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0038] Preferably, the drying temperature is 60 - 100 °C. For example, it can be 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, 95 °C or 100 °C, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0039] Preferably, the drying time is 8 - 12 h. For example, it can be 8 h, 8.5 h, 9 h, 9.5 h, 10 h, 10.5 h, 11 h, 11.5 h or 12 h, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0040] Preferably, the drying is accompanied by stirring, and the stirring rate is 300-600 r / min, for example, it can be 300 r / min, 350 r / min, 400 r / min, 450 r / min, 500 r / min, 550 r / min or 600 r / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] As a preferred technical solution of the preparation method described in the first aspect of the present invention, the preparation method comprises the following steps:

[0042] (1) mixing a carbon material and a metal salt solution at a solid-liquid ratio of (0.3-4):1 g / L at 20-30° C. for 20-28 hours to obtain a mixture;

[0043] The mixing is accompanied by stirring at a stirring rate of 300-600 r / min;

[0044] (2) The mixture obtained in step (1) is dried at 60-100° C. for 8-12 h, ground, and then thermally shocked at 700-1000° C. for 8-40 s in a protective atmosphere to obtain the high entropy alloy catalyst;

[0045] The drying is accompanied by stirring at a stirring rate of 300-600 r / min.

[0046] In a second aspect, the present invention provides a high entropy alloy catalyst, wherein the high entropy catalyst is obtained by the preparation method described in the first aspect.

[0047] In a third aspect, the present invention provides an electrolytic cell, wherein the anode of the electrolytic cell comprises the high entropy alloy catalyst described in the second aspect.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The present invention utilizes a thermal shock method to prepare a high entropy alloy catalyst. The entire process takes less than 1 minute, and can effectively prevent alloy particle agglomeration. Combined with the characteristics of rapid cooling, the structural uniformity of the high entropy alloy catalyst can be maintained to the maximum extent, and phase segregation can be avoided. During the thermal shock process, the carbon material can serve as a carrier to improve the conductivity of the high entropy alloy catalyst, and also acts as a reducing agent to effectively reduce the metal salt to a metal element. At high temperature, the metal element diffuses to form an alloy, and finally generates a high entropy alloy catalyst. The process is simple, easy to control, and has a short flow, which is conducive to realizing large-scale production of the high entropy alloy catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 is a STEM image of the high entropy alloy catalyst obtained in Example 1;

[0051] Figure 2XRD pattern of the high-entropy alloy catalyst obtained in Example 1;

[0052] Figure 3 is the i-t curve of the high-entropy alloy catalyst obtained in Example 1 at a current density of 10 mA / cm 2 ;

[0053] Figure 4 is the i-t curve of the high-entropy alloy catalyst obtained in Example 1 at a current density of 100 mA / cm 2 ;

[0054] Figure 5 is the i-t curve of the high-entropy alloy catalyst obtained in Example 14 at a current density of 10 mA / cm 2 ;

[0055] Figure 6 is the i-t curve of the high-entropy alloy catalyst obtained in Example 14 at a current density of 100 mA / cm 2 ; Detailed implementation manners

[0056] The technical solutions of the present invention will be further described below through specific implementation manners. Those skilled in the art should understand that the described embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0057] Example 1

[0058] This example provides a preparation method of a high-entropy alloy catalyst, and the preparation method includes:

[0059] Mixing a carbon material with a metal salt solution having a concentration of 0.01 mol / mL at 23°C according to a solid-liquid ratio of (1:1) g / L for 24 h. The solvent of the metal salt solution is a mixture of ethanol and water with a volume ratio of 4:1. Then, it is dried at 80°C for 10 h. After grinding, it is thermally shocked at 800°C for 10 s in a nitrogen atmosphere, and the relative pressure during thermal shock is 0 MPa to obtain the high-entropy alloy catalyst;

[0060] The mixing is accompanied by stirring, and the stirring rate is 500 r / min;

[0061] The drying is accompanied by stirring, and the stirring rate is 500 r / min;

[0062] The metal salt solution contains five metal salts, namely ferric chloride, nickel acetylacetonate, cobalt acetate, chromium nitrate, and samarium chloride. The molar fractions of iron, nickel, cobalt, chromium, and samarium elements are 20%, 20%, 20%, 20%, and 20% of the total molar amount of metal elements, respectively;

[0063] The mass ratio of the metal element in the metal salt solution to the carbon material is 20:100.

[0064] Example 2

[0065] This example provides a preparation method of a high-entropy alloy catalyst, and the preparation method includes:

[0066] At 30 °C, a carbon material is mixed with a metal salt solution with a concentration of 0.005 mol / mL and the carbon material according to a solid-liquid ratio of (0.3:1) g / L for 20 h. The solvent of the metal salt solution is a mixture of ethanol and water with a volume ratio of 1:1. Then, it is dried at 60 °C for 12 h. After grinding, it is subjected to a thermal shock at 700 °C for 40 s in an argon atmosphere, and the relative pressure during the thermal shock is 0.1 MPa to obtain the high-entropy alloy catalyst;

[0067] The mixing is accompanied by stirring, and the stirring rate is 300 r / min;

[0068] The drying is accompanied by stirring, and the stirring rate is 600 r / min;

[0069] The metal salt solution contains five metal salts, namely iron nitrate, nickel chloride, cobalt nitrate, chromium nitrate, and samarium acetate. The molar fractions of iron, nickel, cobalt, chromium, and samarium elements are 40%, 5%, 10%, 5%, and 40% of the total molar amount of metal elements, respectively;

[0070] The mass ratio of the metal element in the metal salt solution to the carbon material is 5:100.

[0071] Example 3

[0072] This example provides a preparation method of a high-entropy alloy catalyst, and the preparation method includes:

[0073] At 20 °C, a carbon material is mixed with a metal salt solution with a concentration of 0.1 mol / mL for 28 h. The solvent of the metal salt solution is a mixture of ethanol and water with a volume ratio of 3:1. Then, it is dried at 100 °C for 8 h. After grinding, it is subjected to a thermal shock at 1000 °C for 8 s in a helium atmosphere, and the relative pressure during the thermal shock is -0.05 MPa to obtain the high-entropy alloy catalyst;

[0074] The mixing is accompanied by stirring, and the stirring rate is 600 r / min;

[0075] The drying is accompanied by stirring, and the stirring rate is 300 r / min;

[0076] The metal salt solution contains five metal salts, namely iron acetate, nickel chloride, cobalt chloride, chromium nitrate and samarium acetate. The molar fractions of iron, nickel, cobalt, chromium and samarium elements are 5%, 40%, 20%, 20% and 15% of the total molar amount of metal elements respectively;

[0077] The mass ratio of the metal elements in the metal salt solution to the carbon material is 25:100.

[0078] Example 4

[0079] This example provides a preparation method of a high-entropy alloy catalyst. Except that the mass ratio of the metal elements in the metal salt solution to the carbon material is 3:100, the rest are the same as those in Example 1.

[0080] Example 5

[0081] This example provides a preparation method of a high-entropy alloy catalyst. Except that the mass ratio of the metal elements in the metal salt solution to the carbon material is 27:100, the rest are the same as those in Example 1.

[0082] Example 6

[0083] This example provides a preparation method of a high-entropy alloy catalyst. Except that the samarium chloride in the metal salt solution is replaced by zirconium chloride, and the samarium element is replaced by the zirconium element in an equimolar amount, the rest are the same as those in Example 1.

[0084] Example 7

[0085] This example provides a preparation method of a high-entropy alloy catalyst. Except that the samarium chloride in the metal salt solution is replaced by yttrium nitrate, and the samarium element is replaced by the yttrium element in an equimolar amount, the rest are the same as those in Example 1.

[0086] Example 8

[0087] This example provides a preparation method of a high-entropy alloy catalyst. Except that the samarium chloride in the metal salt solution is replaced by magnesium chloride in an equimolar amount, and the samarium element is replaced by the magnesium element in an equimolar amount, the rest are the same as those in Example 1.

[0088] Example 9

[0089] This example provides a preparation method of a high-entropy alloy catalyst. Except that the samarium chloride in the metal salt solution is replaced by scandium acetate in an equimolar amount, and the samarium element is replaced by the scandium element in an equimolar amount, the rest are the same as those in Example 1.

[0090] Example 10

[0091] This example provides a method for preparing a high-entropy alloy catalyst. Except that an equimolar amount of samarium chloride in the metal salt solution is replaced with manganese acetylacetonate and an equimolar amount of element samarium is replaced with element manganese, the rest is the same as in Example 1.

[0092] Example 11

[0093] This example provides a method for preparing a high-entropy alloy catalyst. Except that an equimolar amount of samarium chloride in the metal salt solution is replaced with zinc chloride and an equimolar amount of element samarium is replaced with element zinc, the rest is the same as in Example 1.

[0094] Example 12

[0095] This example provides a method for preparing a high-entropy alloy catalyst. Except that an equimolar amount of samarium chloride in the metal salt solution is replaced with indium nitrate and an equimolar amount of element samarium is replaced with element indium, the rest is the same as in Example 1.

[0096] Example 13

[0097] This example provides a method for preparing a high-entropy alloy catalyst. Except that an equimolar amount of samarium chloride in the metal salt solution is replaced with gallium acetate and an equimolar amount of element samarium is replaced with element gallium, the rest is the same as in Example 1.

[0098] Example 14

[0099] This example provides a method for preparing a high-entropy alloy catalyst. Except that an equimolar amount of samarium chloride in the metal salt solution is replaced with copper nitrate and an equimolar amount of element samarium is replaced with element copper, the rest is the same as in Example 1.

[0100] Comparative Example 1

[0101] This comparative example provides a method for preparing a high-entropy alloy catalyst. Except that the temperature of the thermal shock is 600 °C, the rest is the same as in Example 1.

[0102] Comparative Example 2

[0103] This comparative example provides a method for preparing a high-entropy alloy catalyst. Except that the temperature of the thermal shock is 1100 °C, the rest is the same as in Example 1.

[0104] Comparative Example 3

[0105] This comparative example provides a method for preparing a high-entropy alloy catalyst. Except that the time of the thermal shock is 5 s, the rest is the same as in Example 1.

[0106] Comparative Example 4

[0107] This comparative example provides a method for preparing a high-entropy alloy catalyst. Except that the time of thermal shock is 43 s, the rest are the same as in Example 1.

[0108] Comparative Example 5

[0109] This comparative example provides a method for preparing a binary alloy catalyst. The metal salt solution contains ferric chloride and nickel acetylacetonate. Except that the molar fractions of iron and nickel are 50% and 50% of the total molar amount of metal elements respectively, that is, the metal salt solution does not contain cobalt acetate, chromium nitrate and samarium chloride, the rest are the same as in Example 1, and the binary alloy catalyst is obtained.

[0110] Comparative Example 6

[0111] This comparative example provides a method for preparing a ternary alloy catalyst. The metal salt solution contains ferric chloride, nickel acetylacetonate and cobalt acetate. Except that the molar fractions of iron, nickel and cobalt are 1 / 3, 1 / 3 and 1 / 3 of the total molar amount of metal elements respectively, that is, the metal salt solution does not contain chromium nitrate and samarium chloride, the rest are the same as in Example 1, and the ternary alloy catalyst is obtained.

[0112] Comparative Example 7

[0113] This comparative example provides a method for preparing a quaternary alloy catalyst. The metal salt solution contains ferric chloride, nickel acetylacetonate, cobalt acetate and chromium nitrate. Except that the molar fractions of iron, nickel and cobalt are 25%, 25%, 25% and 25% of the total molar amount of metal elements respectively, that is, the metal salt solution does not contain samarium chloride, the rest are the same as in Example 1, and the quaternary alloy catalyst is obtained.

[0114] Comparative Example 8

[0115] This comparative example provides a commercial iridium oxide catalyst, sourced from Zhongke Kechuang.

[0116] Performance Test

[0117] For the high-entropy alloy catalysts provided in Examples 1-14 and Comparative Examples 1-4, the binary alloy catalyst provided in Comparative Example 5, the ternary alloy catalyst provided in Comparative Example 6, the quaternary alloy catalyst provided in Comparative Example 7 and the commercial iridium oxide catalyst provided in Comparative Example 8, electrochemical tests and stability tests were carried out. The test methods are as follows:

[0118] Respectively take 5 mg of the high-entropy alloy catalysts of Examples 1-14 and Comparative Examples 1-4, the binary alloy catalyst of Comparative Example 5, the ternary alloy catalyst of Comparative Example 6, the quaternary alloy catalyst of Comparative Example 7 and the commercial iridium oxide catalyst of Comparative Example 8 into a 1 mL centrifuge tube, add them to a mixed solution containing 450 μL of ethanol and 50 μL of 5% Nafion, ultrasonically mix evenly and then drop them onto 0.25 cm2 on the hydrophilic carbon paper, wherein the Ir loading in Comparative Example 8 is 0.2 mg / cm 2 , after the solvent is completely volatilized at room temperature, electrochemical tests and stability tests are carried out; the electrochemical test system is a three-electrode system, the platinum sheet is the counter electrode, the carbon paper is the working electrode, mercury / mercuric oxide is the reference electrode, and the electrolyte is 1 M KOH solution.

[0119] The overpotential (mV@10 mA / cm 2 ) was tested when the current density reached 10 mA / cm 2 , and a constant current stability test was carried out at a current density of 10 mA / cm 2 , and the decay rate (%) after 100 h of cycling was tested. The results are shown in Table 1.

[0120] Table 1

[0121]

[0122]

[0123] As can be seen from Table 1, the overpotential of the high-entropy alloy catalyst obtained by the preparation method provided by the present invention is as low as 244 mV@10 mA / cm 2 during the electrolysis of water, and the decay rate after cycling at a current density of 10 mA / cm 2 for 100 h is only 0.5%, showing good electrocatalytic performance and stability.

[0124] Figure 1 is the STEM diagram of the high-entropy alloy catalyst obtained in Example 1. It can be seen that the particle size distribution of the obtained high-entropy selenide catalyst is relatively narrow, the particle size is about 200 nm, and each metal is relatively evenly distributed on the particles, proving the successful synthesis of the high-entropy alloy catalyst; Figure 2 is the XRD diagram of the high-entropy alloy catalyst obtained in Example 1. It can be seen that the obtained high-entropy alloy catalyst is a single-phase FCC structure; Figure 3 And Figure 4 are the i-t curves of the constant current stability test of the high-entropy alloy catalyst obtained in Example 1 at current densities of 10 mA / cm 2 and 100 mA / cm 2 respectively. It can be seen that the high-entropy alloy catalyst prepared by the present invention can stably operate for more than 100 h at current densities of 10 mA / cm 2 and 100 mA / cm 2 , indicating that the synthesized high-entropy selenide catalyst has good stability.

[0125] From the comparison between Examples 4 and 5 and Example 1, it can be seen that the mass ratio of the metal element in the metal salt solution of the present invention to the carbon material is (5-25):100, which is beneficial to providing abundant active sites for the catalytic reaction and ensuring the dispersion of the metal. When the mass ratio is lower than 5:100, the metal element is too low, resulting in insufficient active sites in the catalyst and an increase in the diffusion distance of metal atoms, which is not conducive to the formation of alloys; when the mass ratio is higher than 25:100, when the metal content is too high, the formed alloy particles are prone to agglomeration, leading to a decrease in catalytic performance.

[0126] From the comparison between Comparative Examples 1 and 2 and Example 1, it can be seen that when the temperature of the thermal shock is lower than 700 °C, it is not sufficient to reduce the metal salt to the elemental state and finally form an alloy, resulting in phase segregation of the material and a decrease in the activity and stability of the high-entropy alloy catalyst; when the temperature is higher than 1000 °C, it is easy for the high-entropy alloy catalyst particles to agglomerate, which is not conducive to the progress of the catalyst reaction. Therefore, controlling the temperature of the thermal shock within the range of 700-1000 °C is beneficial to preventing the agglomeration of alloy particles, maintaining the structural uniformity of the high-entropy alloy catalyst, avoiding phase segregation, and ensuring that the obtained high-entropy alloy catalyst has good catalytic activity and stability.

[0127] From the comparison between Comparative Examples 3 and 4 and Example 1, it can be seen that when the time of the thermal shock is less than 8 s, it is not sufficient to reduce the metal salt and finally form a high-entropy alloy catalyst, resulting in phase segregation of the material; when the time is more than 40 s, it is easy for the alloy particles to agglomerate. Therefore, controlling the time of the thermal shock within the range of 8-40 s is beneficial to preventing the agglomeration of alloy particles, maintaining the structural uniformity of the high-entropy alloy catalyst, avoiding phase segregation, and ensuring that the obtained high-entropy alloy catalyst has good catalytic activity and stability.

[0128] From the comparison between Comparative Examples 5-7 and Example 1, it can be seen that the catalytic stability of the high-entropy alloy catalyst is superior to that of the binary alloy catalyst, ternary alloy catalyst, and quaternary alloy catalyst. This is because the multi-metal active sites in the high-entropy alloy promote the catalytic activity, and the high-entropy effect makes the atomic diffusion slow, thus having higher stability.

[0129] From the comparison between Comparative Example 8 and Example 1, it can be seen that during the catalytic electrolysis of water reaction, the overpotential of the commercial iridium oxide catalyst is 275 mV@10 mA / cm 2 , 10 mA / cm 2 The decay rate after 10 h of cycling is 20%. Therefore, the high-entropy selenide catalyst provided by the present invention has good catalytic activity and stability for electrolyzing water.

[0130] At the same time, the electronegativity of the fifth metal element replaced in the high-entropy alloy catalysts provided in Example 1 and Examples 6-14 was compared, and the overpotential (mV@10 mA / cm2 ) and Tafel slope (mV / dec) at a current density of 10 mA / cm 2 The constant current stability test was carried out under the condition of constant current, and the attenuation rate (%) after 100 hours of cycling was tested. The results are shown in Table 2.

[0131] Table 2

[0132]

[0133]

[0134] As shown in Table 2, the relationship between the overpotential of the high entropy alloy catalyst obtained in Example 1 and Example 6-14 and the electronegativity of the fifth element shows that when the electronegativity is within a certain range, the activity of the catalyst will increase with the increase of electronegativity. This is because as the electronegativity increases, the electron transfer between other metals will be promoted, and the electrocatalytic performance of the catalyst will be improved within a certain range; however, as the electronegativity continues to increase, the activity of the catalyst will decrease instead. This is because when the electronegativity increases to a certain extent, the electron transfer between metals continues to increase, which is not conducive to the interaction between the catalyst and the reaction intermediate, thereby reducing the electrocatalytic activity of the catalyst. The Tafel slope shows a trend of increasing first and then decreasing with the increase of electronegativity. After 100 hours of circulation, the attenuation rate is in the range of 0.5-1.0%, with little difference and good stability. Figure 3 and Figure 4 The high entropy alloy catalyst obtained in Example 14 is respectively 2 and 100mA / cm 2 It curve of the constant current stability test under the current density of 10 mA / cm 2 and 100mA / cm 2 The catalysts can run stably for more than 100 h at current densities of 1.34 and 1.73 %, indicating that the synthesized high-entropy selenide catalysts have good stability.

[0135] In summary, the present invention provides a high entropy alloy catalyst and a preparation method and application thereof. The high entropy alloy catalyst is prepared by a thermal shock method. The whole process takes less than 1 minute, which can effectively prevent the alloy particles from agglomerating. Combined with the characteristics of rapid cooling, the structural uniformity of the high entropy alloy catalyst can be maintained to the maximum extent to avoid phase segregation. During the thermal shock process, the carbon material can act as a carrier to improve the conductivity of the high entropy alloy catalyst and also act as a reducing agent to effectively reduce the metal salt to a metal element. At high temperature, the metal element diffuses to form an alloy, and finally generates a high entropy alloy catalyst. The process is simple, easy to control, and has a short process, which is conducive to the large-scale production of the high entropy alloy catalyst.

[0136] The above are only specific embodiments 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 thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for preparing a high-entropy alloy catalyst, characterized in that, The preparation method includes: Mixing a carbon material with a metal salt solution to obtain a mixture; the mixture is dried, ground, and thermally shocked to obtain the high-entropy alloy catalyst; The carbon material includes carbon black XC-72; The metal salts in the metal salt solution include iron salts, nickel salts, cobalt salts, chromium salts, and samarium salts; The iron salt is composed of any one of iron acetate, iron nitrate, or iron chloride; The nickel salt is composed of nickel chloride or nickel acetylacetonate; The cobalt salt is composed of any one of cobalt acetate, cobalt nitrate, or cobalt chloride; The chromium salt is chromium nitrate; The samarium salt is composed of samarium acetate or samarium chloride; The mass ratio of the metal elements in the metal salt solution to the carbon material is (5-25):100; the temperature of the thermal shock is 700-1000 °C; The time of the thermal shock is 8-40 s.

2. The preparation method according to claim 1, characterized in that, The thermal shock is carried out in a protective atmosphere.

3. The preparation method according to claim 2, characterized in that, The protective atmosphere includes nitrogen and / or inert gas.

4. The preparation method according to claim 3, characterized in that, The inert gas includes any one or a combination of at least two of helium, neon, argon, krypton, or xenon.

5. The preparation method according to claim 1, characterized in that, The relative pressure during the thermal shock is -0.05 to 0.1 MPa.

6. The preparation method according to claim 1, characterized in that, The solid-liquid ratio of the carbon material to the metal salt solution is (0.3-4):1, and the unit of the solid-liquid ratio is g / L.

7. The preparation method according to claim 1, characterized in that, The molar concentration of the metal salt solution is 0.005-0.1 mol / mL.

8. The preparation method according to claim 1, characterized in that, The molar fraction of any one metal element in the metal salt solution relative to the contained metal elements is 5-40%.

9. The preparation method according to claim 1, characterized in that, The solvent of the metal salt solution is a mixture of ethanol and water.

10. The preparation method according to claim 9, characterized in that, In the ethanol and water mixture, the volume ratio of ethanol to water is (1-4):

1.

11. The preparation method according to claim 1, characterized in that, The temperature of the mixing is 20-30 °C.

12. The preparation method according to claim 1, characterized in that, The time of the mixing is 20-28 h.

13. The preparation method according to claim 1, characterized in that, The mixing is accompanied by stirring, and the stirring rate is 300-600 r / min.

14. The preparation method according to claim 1, characterized in that, The temperature of the drying is 60-100 °C.

15. The preparation method according to claim 1, characterized in that, The time of the drying is 8-12 h.

16. The preparation method according to claim 1, wherein, The drying is accompanied by stirring, and the stirring rate is 300-600 r / min.

17. The preparation method according to claim 1, wherein, The preparation method includes: (1) Mixing a carbon material with a solid-liquid ratio of (0.3-4):1 g / L with a metal salt solution at 20-30 °C for 20-28 h to obtain a mixture; The mixing is accompanied by stirring, and the stirring rate is 300-600 r / min; (2) The mixture obtained in step (1) is dried at 60-100 °C for 8-12 h, ground, and then thermally shocked at 700-1000 °C for 8-40 s in a protective atmosphere to obtain the high-entropy alloy catalyst; The drying is accompanied by stirring, and the stirring rate is 300-600 r / min.

18. A high-entropy alloy catalyst, wherein, The high-entropy alloy catalyst is obtained by the preparation method according to any one of claims 1-17.

19. An electrolytic cell, wherein, The anode of the electrolytic cell includes the high-entropy alloy catalyst according to claim 18.

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