High entropy alloy, preparation method thereof, membrane electrode assembly and fuel cell

Abstract

The present application relates to a high-entropy alloy and its preparation method, membrane electrode assembly and fuel cell, wherein the high-entropy alloy comprises at least five metal elements and has the morphology characteristics of two-dimensional nanorings or three-dimensional nanoflowers. The high-entropy alloy comprises at least five metal elements and can construct an entropy-driven, thermodynamically and kinetically stable single-phase solid solution structure, so that it can maintain good stability in severe application environments such as high temperature, corrosion and high electrochemical potential; the high-entropy alloy has a two-dimensional nanoring morphology feature, contains various defects such as unsaturated coordinated atoms and vacancies, so that its active sites are fully exposed; or the high-entropy alloy has a three-dimensional nanoflower morphology feature, which has a large surface area and high mass transfer, and the density of coordinated unsaturated surface atoms on the nanoflower is high, which can effectively enhance the catalytic performance of the high-entropy alloy.

Description

Technical Field

[0001] The present application relates to the field of materials, and in particular to a high entropy alloy and a preparation method thereof, a membrane electrode assembly, and a fuel cell. Background Art

[0002] With the ever-increasing demand for energy and the rapid depletion of fossil resources, electrocatalytic energy conversion reactions have become one of the most promising technologies for developing clean and renewable energy. In terms of energy storage devices, electrochemical reduction of CO2 to high-value-added fuels and chemicals, as well as electrocatalytic water splitting devices driven by renewable electricity, are considered the cleanest energy storage technologies due to their high efficiency and low cost. Furthermore, fuel cell devices, which can convert chemical energy stored in fuels into clean electrical energy through electrochemical processes, also play a vital role in achieving sustainable energy development. However, the practical application of these technologies is still hindered by the kinetic hysteresis of some key reactions. Therefore, the rational design of efficient and durable electrocatalysts for the above reactions is crucial to improving the efficiency of these energy conversion technologies.

[0003] In recent years, binary alloy electrocatalysts have received great attention. It is well known that the adsorption energy of reactant molecules and key intermediates on the surface of an electrocatalyst can be used as a characteristic description of activity, and the electronic structure of the electrocatalyst surface determines the surface adsorption energy. As for the electronic structure, due to the different work functions of different metals, the surface charge of the bimetallic alloy will be redistributed. The electronic properties of the bimetallic alloy directly determine the adsorption and activation of reactants and intermediates, thereby determining the catalytic performance. However, the different metals that make up the binary alloy have different crystal structures, atomic sizes, electronegativity and electron concentrations, resulting in the composition range and formation conditions of the binary alloy being restricted by thermodynamic conditions, which limits the range of electronic structure modulation.

[0004] High-entropy alloys (HEAs) are typically single solid-solution alloys composed of five or more metallic elements, with the atomic fraction of each element ranging from 5% to 35%. Due to their unique physicochemical properties, they have attracted widespread attention across various fields. By miniaturizing HEAs to the nanoscale, their vast compositional space, strong multi-element synergy, significant lattice distortion, and high configurational entropy are expected to endow nanoscale HEAs with unprecedented catalytic activity and stability, thus providing tremendous opportunities for advanced catalyst discovery. To significantly advance the development of HEA catalysts, the synthesis of HEA nanostructures with controlled morphology and rich elemental composition is crucial. This not only maximizes the inherent advantages of HEA catalysts by constructing favorable geometries but also provides a clear platform for understanding the complex structure-property relationships of HEA catalysts. Despite the significant significance of HEA nanostructures, the synthesis of morphologically and compositionally controlled HEA nanostructures remains an open challenge due to the significant differences in reduction potential, atomic size, and electronic structure among the constituent elements.

[0005] Conventional methods for preparing high-entropy alloys (HEAs) include shock-type synthesis and liquid-phase synthesis. Shock-type synthesis involves carbon thermal shock, rapid moving bed pyrolysis, gas-phase spark discharge, and laser-assisted synthesis. This method, driven by a powerful kinetic process, can synthesize HEAs with a wide range of elemental compositions. However, this method requires harsh reaction conditions such as high temperature and high pressure, resulting in the formation of HEAs with nanoparticles, which hinders effective morphological control. Liquid-phase synthesis has recently shown promise for synthesizing HEA nanostructures with diverse morphologies, notably HEA nanowires, nanobelts, and nanoplates. However, these liquid-phase syntheses, whether one-pot or electrochemically induced, primarily focus on noble metals, resulting in a narrow elemental distribution and a lack of universal synthesis. In this context, exploring universal routes for synthesizing HEA nanoalloys with controllable morphology and diverse elemental compositions is of great importance, but to our knowledge, no such approaches have been reported. Summary of the Invention

[0006] Based on this, the present application provides a high-entropy alloy with diverse elemental composition and controllable morphology, a preparation method thereof, a membrane electrode assembly, and a fuel cell.

[0007] The technical solution of this application to solve the above technical problems is as follows.

[0008] On the one hand, the present application provides a high entropy alloy, which contains at least five metal elements and has the morphology characteristics of two-dimensional nanorings or three-dimensional nanoflowers.

[0009] In some embodiments, in the high entropy alloy, the metal elements are selected from at least five of p-block metal elements, d-block metal elements, and ds-block metal elements.

[0010] In some embodiments, in the high entropy alloy, the metal elements are selected from at least five of Ru, Rh, Au, Ir, Pd, Pt, Ag, Cu, Fe, Co, Ni, Pb, Bi, Sn, Sb and Ge.

[0011] In some embodiments, in the high entropy alloy, the metal elements include at least Pd and Pt.

[0012] In some embodiments, the high entropy alloy is selected from one of palladium-platinum-copper-lead-bismuth alloy, palladium-platinum-copper-lead-antimony alloy, palladium-platinum-copper-bismuth-antimony alloy, palladium-platinum-copper-lead ...iron-tin-antimony alloy, palladium-platinum-nickel-tin-antimony alloy, palladium-platinum-cobalt-tin-antimony alloy, palladium-platinum-copper-lead-tin alloy and palladium-platinum-copper-silver-germanium alloy.

[0013] In some embodiments, the high entropy alloy is PdPtCuPbBi two-dimensional nanoring, PdPtCuPbSb two-dimensional nanoring, PdPtCuBiSb two-dimensional nanoring, PdPtCuPbBiSb two-dimensional nanoring, PdPtFeSnSb two-dimensional nanoring, PdPtNiSnSb two-dimensional nanoring, PdPtCoSnSb two-dimensional nanoring, PdPtCuPbSn two-dimensional nanoring, PdPtCuAgGe two-dimensional nanoring or PdPtCuPbBi three-dimensional nanoflower.

[0014] In some embodiments, in the high entropy alloy, the molar ratio of each metal element is 5% to 35%.

[0015] On the other hand, the present application provides a method for preparing a high entropy alloy, comprising the following steps:

[0016] A nanomaterial is mixed with a metal salt precursor, a surfactant, a reducing agent and a solvent to perform an oxidation-reduction reaction to generate a high-entropy alloy with a morphology corresponding to that of the nanomaterial; the nanomaterial contains 2 to 4 metal elements M; the metal salt precursor contains at least one metal element N that is different from the metal element M, and the number of metal elements in the nanomaterial and the metal salt precursor is not less than 5.

[0017] In some embodiments, in the preparation method of the high entropy alloy, the morphology of the nanomaterial is selected from one of zero-dimensional nanoparticles, one-dimensional nanowires, two-dimensional nanosheets, two-dimensional nanorings and three-dimensional nanoflowers, and the morphology of the high entropy alloy corresponds to zero-dimensional nanoparticles, one-dimensional nanowires, two-dimensional nanorings, two-dimensional nanorings and three-dimensional nanoflowers, respectively.

[0018] In some embodiments, in the method for preparing a high entropy alloy, the nanomaterial is selected from one of PdPtCu zero-dimensional nanoparticles, PdPtCu one-dimensional nanowires, PdPtCu two-dimensional nanosheets, PdPtFe two-dimensional nanosheets, PdPtCo two-dimensional nanosheets, PdPtNi two-dimensional nanosheets and PdPtCu three-dimensional nanoflowers.

[0019] In some embodiments, in the method for preparing a high entropy alloy, the metal salt precursor is selected from at least one of chlorate, sodium chlorate, potassium chlorate, acetylacetonate, nitrate, chloride and decanoate.

[0020] In some embodiments, in the method for preparing a high entropy alloy, the surfactant is polyvinyl pyrrolidone.

[0021] In some embodiments, in the method for preparing a high entropy alloy, the reducing agent is selected from at least one of ascorbic acid, potassium bromide, and citric acid monohydrate.

[0022] In some embodiments, in the method for preparing a high entropy alloy, the solvent is selected from at least one of N-dimethylacetamide, ethylene glycol, oleylamine, benzyl alcohol and water.

[0023] In some embodiments, in the method for preparing a high entropy alloy, the temperature of the redox reaction is 140°C to 180°C.

[0024] In some embodiments, in the method for preparing a high entropy alloy, the redox reaction is carried out under nitrogen conditions.

[0025] The present application also provides a membrane electrode assembly, comprising a proton exchange membrane and a catalytic layer, wherein the catalytic layer is arranged on both sides of the proton exchange membrane, and at least one catalytic layer comprises the above-mentioned high entropy alloy or the high entropy alloy prepared by the above-mentioned preparation method.

[0026] The present application also provides a fuel cell comprising the above-mentioned membrane electrode assembly.

[0027] Compared with the prior art, the high entropy alloy of the present application has the following beneficial effects:

[0028] The above-mentioned high-entropy alloy contains at least five metal elements, which can construct an entropy-driven, thermodynamically and kinetically stable single-phase solid solution structure, so that it can maintain good stability in harsh application environments such as high temperature, corrosion and high electrochemical potential; and the high-entropy alloy has a two-dimensional nano-ring morphology feature, containing various defects such as unsaturated coordinated atoms (platform sites, step sites) and vacancies, so that its active sites are fully exposed, effectively improving the catalytic performance of the high-entropy alloy, and its application in fuel cells can effectively promote the kinetic process in the oxidation process; or the high-entropy alloy has a three-dimensional nano-flower morphology feature, which has a large number of nano-mesopores, and the spatially limited nano-mesopores provide channels for the generation of catalytic intermediates, and optimize the electronic structure and coordination environment of the metal sites, which can effectively enhance the catalytic performance of the high-entropy alloy.

[0029] The above-mentioned preparation method of the high-entropy alloy uses a nanomaterial containing 2 to 4 metal elements M as a seed crystal. The morphological characteristics of the seed crystal are relatively stable. The seed crystal undergoes an oxidation-reduction reaction with a metal salt precursor containing at least one metal element N different from the metal element M under the action of a surfactant, a reducing agent and a solvent. A high-entropy alloy containing at least five metal elements having a morphology corresponding to that of the nanomaterial can be stably generated. The preparation method can control the morphology of the prepared high-entropy alloy, and the elemental composition has a wide applicability. The stability and catalytic performance of the prepared high-entropy alloy are good, and the preparation steps are simple and the reaction conditions are mild. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0031] Figure 1 TEM image of PdPtCuPbBi UNRs prepared in Example 3;

[0032] Figure 2 TEM image of PdPtCuPbBi NDs prepared in Example 4;

[0033] Figure 3 TEM image of PdPtCuPbBi NPs prepared in Example 1;

[0034] Figure 4 TEM image of PdPtCuPbBi NWs prepared in Example 2;

[0035] Figure 5TEM image of PdPtCuPbBi NPs prepared in Comparative Example 1;

[0036] Figure 6 TEM image of the raw material Pd nanosheets used in Comparative Example 2;

[0037] Figure 7 TEM image of PdPtCuPbBi NPs prepared in Comparative Example 2;

[0038] Figure 8 The XRD spectrum of PdPtCuPbBi UNRs prepared in Example 3;

[0039] Figure 9 This is the XPS spectrum of PdPtCuPbBi UNRs prepared in Example 3;

[0040] Figure 10 This is the EDS elemental analysis spectrum of PdPtCuPbBi UNRs prepared in Example 3;

[0041] Figure 11 Graph showing the electrocatalytic ethanol oxidation test results of the high entropy alloys prepared in Examples 1, 2, and 4;

[0042] Figure 12 Figure 3 shows the electrocatalytic ethanol oxidation test results of PdPtCu NSs / C and PdPtCuPbBi UNRs / C, as well as Pd / C and Pt / C catalysts prepared in Example 3;

[0043] Figure 13 Graph showing the electrocatalytic ethanol oxidation test results of the high entropy alloys prepared in Comparative Examples 1 and 2;

[0044] Figure 14 Figure 2 shows the stability test results of PdPtCu NSs / C, PdPtCuPbBi UNRs / C, Pd / C and Pt / C catalysts. DETAILED DESCRIPTION

[0045] The technical solutions of the present application are further described in detail below with reference to specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. It should be understood that the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of the present application.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0047] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0048] The weights of the relevant components mentioned in the examples of this application may not only refer to the specific content of each component, but also represent the weight ratio between the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the examples of this application, it is within the scope disclosed in the examples of this application. Specifically, the weights described in the examples of this application may be mass units known in the chemical industry, such as μg, mg, g, and kg.

[0049] See also Figures 1 and 2 One embodiment of the present application provides a high entropy alloy comprising at least five metal elements and having the morphological characteristics of a two-dimensional nanoring or a three-dimensional nanoflower.

[0050] The above-mentioned high-entropy alloy contains at least five metal elements, which can construct an entropy-driven, thermodynamically and kinetically stable single-phase solid solution structure, so that it can maintain good stability in harsh application environments such as high temperature, corrosion and high electrochemical potential; and the high-entropy alloy has a two-dimensional nano-ring morphology feature, containing various defects such as unsaturated coordinated atoms (platform sites, step sites) and vacancies, so that its active sites are fully exposed, effectively improving the catalytic performance of the high-entropy alloy, and its application in fuel cells can effectively promote the kinetic process in the oxidation process; or the high-entropy alloy has a three-dimensional nano-flower morphology feature, which has a large number of nano-mesopores, and the spatially limited nano-mesopores provide channels for the generation of catalytic intermediates, and optimize the electronic structure and coordination environment of the metal sites, which can effectively enhance the catalytic performance of the high-entropy alloy.

[0051] It can be understood that the number of metal element types in high entropy alloys includes but is not limited to five, six, seven, eight, nine, and ten; accordingly, high entropy alloys are five-element alloys, six-element alloys, seven-element alloys, eight-element alloys, nine-element alloys, and ten-element alloys.

[0052] In some examples, in the high entropy alloy, the metal element is selected from at least one of a p-block metal element, a d-block metal element, and a ds-block metal element.

[0053] Furthermore, the metal elements are selected from at least five of p-block metal elements, d-block metal elements, and ds-block metal elements.

[0054] It can be understood that the p-zone metal elements include metal elements from Group IIIA to Group 0 in the periodic table, such as: aluminum Al, gallium Ga, indium In, thallium Tl, germanium Ge, tin Sn, lead Pb, antimony Sb, bismuth Bi and polonium Po; the d-zone metal elements include metal elements from Group IIIB to Group VIII; the ds-zone metal elements include elements from Groups IB and IIB; among them, the d-zone and ds-zone metal elements include precious metal elements, and the precious metal elements include gold Au, silver Ag and platinum group metals, among which the platinum group metals include ruthenium Ru, rhodium Rh, palladium Pd, osmium Os, iridium Ir and platinum Pt.

[0055] In some examples, in the high entropy alloy, the metal elements are selected from at least five of Ru, Rh, Au, Ir, Pd, Pt, Ag, Cu, Fe, Co, Ni, Pb, Bi, Sn, Sb, and Ge.

[0056] Furthermore, the metal elements are selected from at least five of Pd, Pt, Ag, Cu, Fe, Co, Ni, Pb, Bi, Sn, Sb and Ge.

[0057] In some of these examples, the high entropy alloys contain at least Pd and Pt as metal elements.

[0058] In some examples, the high entropy alloy is selected from one of palladium-platinum-copper-lead-bismuth alloy, palladium-platinum-copper-lead-antimony alloy, palladium-platinum-copper-bismuth-antimony alloy, palladium-platinum-copper-lead ...iron-tin-antimony alloy, palladium-platinum-nickel-tin-antimony alloy, palladium-platinum-cobalt-tin-antimony alloy, palladium-platinum-copper-lead-tin alloy and palladium-platinum-copper-silver-germanium alloy.

[0059] It can be understood that the morphology of the above-mentioned high entropy alloy can be a two-dimensional nanoring or a three-dimensional nanoflower.

[0060] In some specific examples, the high entropy alloy is PdPtCuPbBi two-dimensional nanoring, PdPtCuPbSb two-dimensional nanoring, PdPtCuBiSb two-dimensional nanoring, PdPtCuPbBiSb two-dimensional nanoring, PdPtFeSnSb two-dimensional nanoring, PdPtNiSnSb two-dimensional nanoring, PdPtCoSnSb two-dimensional nanoring, PdPtCuPbSn two-dimensional nanoring, PdPtCuAgGe two-dimensional nanoring or PdPtCuPbBi three-dimensional nanoflower.

[0061] It can be understood that the element symbols in the high entropy alloys listed in the above examples, such as "PdPtCuPbBi" in the PdPtCuPbBi two-dimensional nanoring, represent the types of metal elements contained in the high entropy alloy, and do not represent the molar ratio or mass ratio between the elements.

[0062] In some examples, the molar proportion of each metal element in the high-entropy alloy is 5% to 35%.

[0063] It is understood that the molar percentages of the metal elements may be the same or different. It is further understood that the molar percentages of the metal elements independently include, but are not limited to, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, and 35%. In some examples, the molar percentages may be within a range formed by any two of these values. The same applies hereinafter.

[0064] An embodiment of the present application provides a method for preparing a high entropy alloy, comprising step S10:

[0065] Step S10: Mixing the nanomaterial with a metal salt precursor, a surfactant, a reducing agent, and a solvent to perform an oxidation-reduction reaction to generate a high-entropy alloy with a morphology corresponding to that of the nanomaterial; the nanomaterial contains 2 to 4 metal elements M; the metal salt precursor contains at least one metal element N different from the metal element M, and the number of metal elements in the nanomaterial and the metal salt precursor is not less than 5.

[0066] The above-mentioned preparation method of the high-entropy alloy uses a nanomaterial containing 2 to 4 metal elements M as a seed crystal. The seed crystal has good morphological characteristics and stability. It undergoes an oxidation-reduction reaction with a metal salt precursor containing at least one metal element N different from the metal element M under the action of a surfactant, a reducing agent and a solvent. A high-entropy alloy containing at least five metal elements with a morphology corresponding to the morphology of the nanomaterial can be stably generated. The preparation method can control the morphology of the prepared high-entropy alloy, and the elemental composition is widely applicable. The stability and catalytic performance of the prepared high-entropy alloy are good.

[0067] It can be understood that the preparation method of the high entropy alloy provided in this application can prepare the above-mentioned high entropy alloys with two-dimensional nanorings or three-dimensional nanoflower morphology characteristics, and can also prepare high entropy alloys with zero-dimensional nanoparticles and one-dimensional nanowire morphology characteristics.

[0068] It can be understood that the morphology of the high entropy alloy prepared in step S10 is mainly determined by the morphology of the nanomaterial.

[0069] In some of these examples, the morphology of the nanomaterial is selected from one of zero-dimensional nanoparticles, one-dimensional nanowires, two-dimensional nanosheets, two-dimensional nanorings and three-dimensional nanoflowers, and accordingly, the morphology of the high-entropy alloy corresponds to zero-dimensional nanoparticles, one-dimensional nanowires, two-dimensional nanorings, two-dimensional nanorings and three-dimensional nanoflowers, respectively.

[0070] That is, when the morphology of the nanomaterial is zero-dimensional nanoparticles, a high-entropy alloy with the morphology of zero-dimensional nanoparticles can be generated; when the morphology of the nanomaterial is one-dimensional nanowires, a high-entropy alloy with the morphology of one-dimensional nanowires can be generated; when the morphology of the nanomaterial is two-dimensional nanosheets or two-dimensional nanorings, a high-entropy alloy with the morphology of two-dimensional nanorings can be generated; when the morphology of the nanomaterial is three-dimensional nanoflowers, a high-entropy alloy with the morphology of three-dimensional nanoflowers can be generated.

[0071] In some examples, in the nanomaterial of step S10 , the particle size of the zero-dimensional nanoparticles is 5 nm to 7 nm.

[0072] Correspondingly, in the high entropy alloy of step S10, the particle size of the zero-dimensional nanoparticles is 5.2 nm to 8 nm.

[0073] Optionally, in the nanomaterial, the particle size of the zero-dimensional nanoparticles is 5.92 nm; correspondingly, in the high entropy alloy, the particle size of the zero-dimensional nanoparticles is 6.45 nm.

[0074] In some examples, in the nanomaterial of step S10 , the radial diameter of the one-dimensional nanowire is 2.5 nm to 4 nm.

[0075] Correspondingly, in the high entropy alloy of step S10, the radial diameter of the one-dimensional nanowire is 2 nm to 4 nm.

[0076] Optionally, in the nanomaterial, the radial diameter of the one-dimensional nanowire is 3.45 nm; correspondingly, in the high entropy alloy, the radial diameter of the one-dimensional nanowire is 2.88 nm.

[0077] In some examples, in the nanomaterial of step S10 , the radial diameter of the two-dimensional nanosheet is 30 nm to 40 nm, and the thickness is 1 nm to 2 nm.

[0078] Correspondingly, in the high entropy alloy of step S10 , the radial diameter of the two-dimensional nanoring is 20 nm to 40 nm, and the thickness is 2 nm to 3 nm.

[0079] It can be understood that the radial diameter of the two-dimensional nanosheet is the width of the two-dimensional nanosheet; further, multiple two-dimensional nanorings can exist in an interconnected manner.

[0080] Optionally, in the nanomaterial, the radial diameter of the two-dimensional nanosheet is 34.8 nm and the thickness is 1.41 nm; correspondingly, in the high entropy alloy, the radial diameter of the two-dimensional nanosheet is 29.3 nm and the thickness is 2.58 nm.

[0081] In some examples, in the nanomaterial of step S10 , the radial size of the three-dimensional nanoflowers is 40 nm to 50 nm.

[0082] Correspondingly, in the high entropy alloy of step S10, the radial size of the three-dimensional nanoflowers is 35 nm to 48 nm.

[0083] Optionally, in the nanomaterial, the radial diameter of the three-dimensional nanoflower is 44.1 nm; correspondingly, in the high entropy alloy, the radial diameter of the three-dimensional nanoflower is 41.21 nm.

[0084] It can be understood that the metal elements M contained in the nanomaterial can be 2, 3 or 4, corresponding to binary alloys, ternary alloys or quaternary alloys respectively.

[0085] In some examples, in step S10, the metal elements M in the nanomaterial are selected from 2 to 4 of Pd, Pt, Ag, Cu, Fe, Co, Ni, Pb, Bi, Sn, Sb and Ge.

[0086] In some examples, in step S10, the nanomaterial contains at least Pd and Pt elements, that is, the nanomaterial is a palladium-platinum alloy.

[0087] In some examples, in step S10 , the nanomaterial is selected from one of palladium-platinum-copper alloy, palladium-platinum-iron alloy, palladium-platinum-cobalt alloy and palladium-platinum-nickel alloy.

[0088] In some examples, in step S10, the nanomaterial is selected from one of PdPtCu zero-dimensional nanoparticles, PdPtCu one-dimensional nanowires, PdPtCu two-dimensional nanosheets, PdPtFe two-dimensional nanosheets, PdPtCo two-dimensional nanosheets, PdPtNi two-dimensional nanosheets and PdPtCu three-dimensional nanoflowers.

[0089] It can be understood that the element symbols in the nanomaterials listed in the above examples, such as "PdPtCu" in PdPtCu zero-dimensional nanoparticles, represent the types of metal elements contained in the high entropy alloy, and do not represent the molar ratio or mass ratio between the elements.

[0090] It is understood that nanomaterials with zero-dimensional nanoparticles, one-dimensional nanowires, two-dimensional nanosheets or three-dimensional nanoflower morphologies can be obtained commercially or prepared by traditional methods.

[0091] It can be further understood that the morphology of nanomaterials is controlled by the precursor reduction, deposition and diffusion processes.

[0092] In some specific examples, in step S10, the preparation of PdPtCu zero-dimensional nanoparticles includes step S110:

[0093] 10.0 mg of sodium chloropalladate, 18.8 mg of platinum acetylacetonate, 9.0 mg of copper acetylacetonate, 20.0 mg of potassium bromide, 3.0 mL of oleylamine and 0.5 mL of ethylene glycol were mixed uniformly, and stirred at 160° C. for 11 h.

[0094] Furthermore, in step S110, the reaction solution is cooled to room temperature and then centrifuged and washed in sequence.

[0095] Furthermore, in step S110, the washing solution is hexane and ethanol.

[0096] Furthermore, in step S110, the volume ratio of hexane to ethanol is 2:1.

[0097] In some examples, in step S10, the preparation of PdPtCu one-dimensional nanowires includes step S120:

[0098] 0.2 mL of a 20 mmol / L aqueous solution of sodium chloropalladate, 0.2 mL of a 20 mmol / L aqueous solution of chloroplatinic acid, 0.2 mL of a 20 mmol / L aqueous solution of copper nitrate, 30.0 mg of dioctadecyldimethylammonium chloride, and 10.0 mL of water were stirred at 95°C for 30 min, and then 1.0 mL of a 0.3 mol / L aqueous solution of ascorbic acid was added, and the reaction was continued at 95°C for 30 min.

[0099] Furthermore, in step S120, the reaction solution is cooled to room temperature and then centrifuged and washed in sequence.

[0100] Furthermore, in step S120, the washing solution is ethanol.

[0101] In some examples, in step S10, the preparation of PdPtCu two-dimensional nanosheets includes step S130:

[0102] After uniformly mixing 16.0 mg of palladium acetylacetonate, 16.0 mg of platinum acetylacetonate, 15.0 mg of copper acetylacetonate, 90.0 mg of citric acid monohydrate, 30.0 mg of potassium bromide, 30.0 mg of polyvinylpyrrolidone and 10.0 mL of NN dimethylformamide, 75.0 mg of molybdenum hexacarbonyl was added, and the mixture was kept at 80°C for 3 h, and then the temperature was increased to 150°C and kept for 6 h.

[0103] Furthermore, in step S130, the reaction solution is cooled to room temperature and then centrifuged and washed in sequence.

[0104] Furthermore, in step S130, the washing solution is ethanol.

[0105] In some examples, in step S10, the preparation of PdPtCu three-dimensional nanoflowers includes step S140:

[0106] Mix 0.5 mL of 20 mM sodium chloropalladate aqueous solution, 0.5 mL of 20 mM sodium hexachloroplatinate aqueous solution, 0.5 mL of 20 mM copper chloride aqueous solution, 1.0 mL of 0.3 M ascorbic acid aqueous solution, 320.0 mg of hexadecyltrimethylammonium bromide and 4.3 mL of water, and keep warm at 95°C for 45 minutes.

[0107] Furthermore, in step S140, the reaction solution is cooled to room temperature and then centrifuged and washed in sequence.

[0108] Furthermore, in step S140, the washing solution is water.

[0109] In some examples, in step S10, the metal element Q in the metal salt precursor is selected from at least one of Pd, Pt, Ag, Cu, Fe, Co, Ni, Pb, Bi, Sn, Sb, and Ge.

[0110] It can be understood that the metal element Q in the metal salt precursor contains at least one metal element N different from the metal element M; it can be further understood that the metal element Q in the metal salt precursor can be only the metal element N, or can include both the metal element N and the metal element M.

[0111] In some examples, in step S10 , the metal salt precursor is selected from at least one of chlorate, sodium chlorate, potassium chlorate, acetylacetonate, nitrate, chloride, and decanoate of the metal element in the metal salt precursor.

[0112] That is, the metal salt precursor is selected from at least one of chlorate of metal element Q, sodium chlorate of metal element Q, potassium chlorate of metal element Q, acetylacetonate of metal element Q, nitrate of metal element Q, chloride of metal element Q and decanoate of metal element Q.

[0113] Furthermore, sodium chlorate salts include but are not limited to sodium tetrachlorate salt and sodium hexachlorate salt; potassium chlorate salts include but are not limited to potassium tetrachlorate salt and sodium potassium hexachlorate salt.

[0114] Taking the metal element Q including Pd as an example, the metal salt precursor of Pd can be chloropalladic acid, sodium tetrachloropalladate, sodium hexachloropalladate, potassium tetrachloropalladate, potassium hexachloropalladate, palladium acetylacetonate, palladium nitrate, palladium chloride, palladium decanoate, etc.

[0115] In some specific examples, in step S10, the metal salt precursor is selected from at least one of sodium chloropalladate, palladium acetylacetonate, platinum acetylacetonate, chloroplatinic acid, sodium hexachloroplatinate, copper acetylacetonate, copper nitrate, copper chloride, lead acetylacetonate and bismuth decanoate.

[0116] It is understood that surfactants include, but are not limited to, cationic surfactants, anionic surfactants, zwitterionic surfactants, and nonionic surfactants. It is further understood that surfactants include, but are not limited to, polyvinyl pyrrolidone, hexadecyl trimethyl ammonium bromide (C 19 H 42 BrN), hexadecyltrimethylammonium chloride, sodium dodecylbenzenesulfonate, polyoxypropylene polyoxyethylene copolymer, tetradecyltrimethylammonium bromide.

[0117] In some examples, in step S10 , the surfactant is polyvinyl pyrrolidone.

[0118] Furthermore, the surfactant is polyvinyl pyrrolidone.

[0119] It is understood that reducing agents include but are not limited to ascorbic acid, glucose (C6H 12 O6), hexacarbonyl tungsten (W(CO)6), oxalic acid, sodium citrate, L-ascorbic acid, ethylene glycol, N,N-dimethylformamide, formic acid or sodium borohydride.

[0120] In some examples, in step S10 , the reducing agent is selected from at least one of ascorbic acid, potassium bromide, and citric acid monohydrate.

[0121] Furthermore, the reducing agent is ascorbic acid.

[0122] In some examples, in step S10 , the molar ratio of the total molar amount of the metal element Q in the metal salt precursor to the surfactant and the reducing agent is (0.66-0.80):(0.001-0.02):1.

[0123] It is understood that the solvent is not limited to N, N-dimethylformamide, ethylene glycol, water, ethanol, isopropanol, acetone, tetrahydrofuran, n-butanol, oleylamine (C 18 H 37 N), dimethyl sulfoxide or toluene.

[0124] In some examples, in step S10 , the solvent is selected from at least one of N-dimethylacetamide, ethylene glycol, oleylamine, benzyl alcohol, and water.

[0125] Furthermore, the solvent is a mixed solvent of N-N-dimethylacetamide and ethylene glycol.

[0126] Furthermore, the volume ratio of NN dimethylacetamide to ethylene glycol is (1-3):1.

[0127] Optionally, the volume ratio of NN dimethylacetamide to ethylene glycol is 2:1.

[0128] In some examples, in step S10 , the temperature of the redox reaction is 140° C. to 180° C.

[0129] It will be appreciated that the temperature of the redox reaction includes but is not limited to 140°C, 142°C, 145°C, 148°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, and 180°C.

[0130] It can be understood that in step S10, the redox reaction is carried out under a protective atmosphere, and the protective atmosphere is selected from at least one of nitrogen and an inert gas.

[0131] It can be understood that the inert gas includes but is not limited to neon and argon.

[0132] Furthermore, the protective atmosphere is selected from at least one of nitrogen and argon.

[0133] Optionally, the redox reaction is carried out under nitrogen conditions.

[0134] In some examples, in step S10 , the nanomaterial is mixed with a metal salt precursor, a surfactant, a reducing agent, and a solvent, and then ultrasonically treated, and then a redox reaction is performed in the aforementioned atmosphere and at the aforementioned temperature.

[0135] In some examples, after the redox reaction is completed, step S10 further includes a step of post-treating the reaction solution obtained after the redox reaction:

[0136] After the reaction solution was cooled to room temperature, centrifugation and washing were performed in sequence.

[0137] Furthermore, the centrifugal rotation speed is 13000 r / min to 13500 r / min.

[0138] Optionally, the centrifugal rotation speed is 13500 r / min.

[0139] Furthermore, the cleaning solvent is selected from at least one of ethanol, hexane and water.

[0140] One embodiment of the present application provides the use of the above-mentioned high entropy alloy or the high entropy alloy prepared by the preparation method in the preparation of a fuel cell.

[0141] One embodiment of the present application provides a membrane electrode assembly, including a proton exchange membrane and a catalyst layer, the catalyst layer is arranged on both sides of the proton exchange membrane, and at least one catalyst layer contains the above-mentioned high entropy alloy or the high entropy alloy prepared by the above-mentioned preparation method.

[0142] It can be understood that the catalytic layer includes an anode catalytic layer and a cathode catalytic layer.

[0143] Furthermore, the membrane electrode assembly further includes a gas diffusion layer, which is arranged on a side of the catalyst layer away from the proton exchange membrane.

[0144] It can be understood that the gas diffusion layer includes a cathode gas diffusion layer and an anode gas diffusion layer. The anode gas diffusion layer is arranged on the side of the anode catalyst layer away from the proton exchange membrane, and the cathode gas diffusion layer is arranged on the side of the cathode catalyst layer away from the proton exchange membrane.

[0145] That is, in some of the examples, in the membrane electrode assembly, a cathode diffusion layer, a cathode catalyst layer, a proton exchange membrane, an anode catalyst layer and an anode gas diffusion layer are stacked in sequence, and at least one of the anode catalyst layer and the cathode catalyst layer contains the above-mentioned high entropy alloy or the high entropy alloy obtained by the above-mentioned preparation method.

[0146] Another embodiment of the present application provides a fuel cell, including the use of the above-mentioned high entropy alloy or the high entropy alloy prepared by the preparation method in the preparation of a fuel cell.

[0147] Furthermore, the fuel cell includes an anode plate, a cathode plate and the above-mentioned membrane electrode assembly, the anode plate is arranged on the side of the anode catalyst layer away from the proton exchange membrane, and the cathode plate is arranged on the side of the cathode catalyst layer away from the proton exchange membrane.

[0148] Applying the above-mentioned high entropy alloy as a catalytic material in fuel cells not only has better stability, but can also effectively improve the catalytic performance of fuel cells.

[0149] The following examples are based on the high entropy alloy and its preparation method, membrane electrode assembly and fuel cell of the present application. It can be understood that the high entropy alloy and its preparation method, membrane electrode assembly and fuel cell of the present application are not limited to the following embodiments.

[0150] Example 1

[0151] Preparation of PdPtCuPbBi zero-dimensional nanoparticles (PdPtCuPbBi NPs)

[0152] (1) Preparation of PdPtCu nanoparticles (PdPtCu NPs)

[0153] To a 30 mL reaction flask, 10.0 mg of sodium chloropalladate, 18.8 mg of platinum acetylacetonate, 9.0 mg of copper acetylacetonate, 20.0 mg of potassium bromide, 3.0 mL of oleylamine, and 0.5 mL of ethylene glycol were added in sequence. A stirring bar was added, the cap was tightened, and the reaction flask was placed on a stirring table and stirred for 45 minutes to mix the solution evenly. After stirring, the reaction flask was heated and stirred in a 160°C oil bath for 11 hours and then cooled naturally to room temperature. The reaction solution was collected by centrifugation at 13,000 rpm and washed twice with hexane and ethanol (hexane:ethanol, volume ratio: 2:1) to obtain the product, PdPtCu nanoparticles.

[0154] (2) Using PdPtCu nanoparticles as seeds, PdPtCuPbBi zero-dimensional nanoparticles were prepared

[0155] The PdPtCu nanoparticles obtained after centrifugal washing of 0.75 mL of the reaction solution containing PdPtCu nanoparticles in step (1) were dispersed in a mixed solution of 4.0 mL NN dimethylacetamide (DMAC) and 2.0 mL ethylene glycol, and then the solution was transferred to a 30 mL reaction bottle, and 30.0 mg polyvinyl pyrrolidone, 5.0 mg ascorbic acid, 0.8 mg lead acetylacetonate and 2.0 mg bismuth decanoate were added. After ultrasonic treatment for 1 hour, nitrogen was introduced for 10 minutes, and then a stirring bar was added and the bottle cap was tightened. The reaction bottle was placed in a 140°C oil bath and vigorously stirred for 12 hours, and naturally cooled to room temperature. The reaction solution was centrifuged at 13000 r / min and washed twice with hexane and ethanol (hexane and ethanol volume ratio is 2:1) to obtain high entropy alloy PdPtCuPbBi zero-dimensional nanoparticles, whose TEM image is shown as follows. Figure 3 shown.

[0156] Example 2

[0157] Preparation of PdPtCuPbBi one-dimensional nanowires (PdPtCuPbBi NWs)

[0158] (1) Preparation of PdPtCu nanowires (PdPtCu NWs)

[0159] In a 30 mL reaction flask, 0.2 mL of sodium chloropalladate aqueous solution (concentration: 20 mmol / L), 0.2 mL of chloroplatinic acid aqueous solution (concentration: 20 mmol / L), 0.2 mL of copper nitrate aqueous solution (concentration: 20 mmol / L), 30.0 mg of dioctadecyldimethylammonium chloride, and 10.0 mL of ultrapure water were added in sequence. A stirring bar was added, and the cap was tightened. The reaction flask was placed in an oil bath and heated with stirring at 95°C for 30 min. Subsequently, 1.0 mL of ascorbic acid aqueous solution (concentration: 0.3 mol / L) was rapidly injected into the sample bottle, and the reaction was continued at 95°C for 30 min. The mixture was naturally cooled to room temperature. The product was collected by centrifugation at 13500 r / min, washed twice with ethanol, and dispersed in 3.0 mL of NN-dimethylacetamide to obtain a NN-dimethylacetamide mixture of PdPtCu nanowires.

[0160] (2) Preparation of PdPtCuPbBi one-dimensional nanowires using PdPtCu nanowires as seeds

[0161] In a 30 mL reaction flask, 4 mL of a NN-dimethylacetamide mixture of PdPtCu nanowires, 2.0 mL of ethylene glycol, 30.0 mg of polyvinyl pyrrolidone, 0.8 mg of lead acetylacetonate, 5.0 mg of ascorbic acid, and 2.0 mg of bismuth decanoate were added in sequence, and the solution was mixed evenly by ultrasonic treatment. Nitrogen was introduced for 10 min, a stirring bar was added, and the cap was tightened. The reaction flask was placed in a 140 ° C oil bath and vigorously stirred for 5 h, then heated to 160 ° C and continued to react for 5 h. After cooling naturally to room temperature, the solution was collected by centrifugation at 13500 r / min, and the solid was washed twice with ultrapure water to obtain PdPtCuPbBi one-dimensional nanowires. The TEM image is shown in FIG. Figure 4 shown.

[0162] Example 3

[0163] Preparation of PdPtCuPbBi two-dimensional ultrathin nanorings (PdPtCuPbBi UNRs)

[0164] (1) Preparation of PdPtCu nanosheets (PdPtCu NSs)

[0165] 16.0 mg of palladium acetylacetonate, 16.0 mg of platinum acetylacetonate, 15.0 mg of copper acetylacetonate, 90.0 mg of citric acid monohydrate, 30.0 mg of potassium bromide, 30.0 mg of polyvinylpyrrolidone and 10.0 mL of NN dimethylformamide were weighed and added to a 30 mL sample bottle and stirred for 1 hour; 75.0 mg of molybdenum hexacarbonyl was added to the solution, heated in an oil bath and kept at 80°C for 3 hours, then heated to 150°C and kept for 6 hours; after naturally cooling to room temperature, 1 mL of the mixture was taken and collected by centrifugation at 13500 r / min. The resulting solid was washed twice with ethanol to obtain PdPtCu nanosheets.

[0166] (2) Using PdPtCu nanosheets as seeds, PdPtCuPbBi two-dimensional ultrathin nanorings were prepared

[0167] The PdPtCu nanosheets obtained after centrifugal washing of 1 mL of the mixture in step (1) were dispersed in a mixed solution of 4.0 mL of NN-dimethylacetamide and 2.0 mL of ethylene glycol, and then 30.0 mg of polyvinyl pyrrolidone, 5.0 mg of ascorbic acid, 0.8 mg of lead acetylacetonate, and 2.0 mg of bismuth decanoate were added and ultrasonically treated for 2 h; nitrogen was introduced for 10 min, and then the bottle was covered with a cap and vigorously stirred in an oil bath at 160° C. for 10 h; naturally cooled to room temperature; centrifuged at 13500 r / min, and the obtained solid was washed twice with ethanol to obtain PdPtCuPbBi two-dimensional ultrathin nanorings, whose TEM image is shown as follows. Figure 1 As shown. Figure 1As can be seen in the figure, the synthesized nanorings are uniformly distributed, with a lateral size of about 29.3 nm and a thickness of about 2.6 nm.

[0168] Example 4

[0169] Preparation of PdPtCuPbBi three-dimensional nanoflowers (PdPtCuPbBi NDs)

[0170] (1) Preparation of PdPtCu nanoflowers (PdPtCu NDs)

[0171] Weigh sodium chloropalladate (0.5 mL 20 mM), sodium hexachloroplatinate (0.5 mL 20 mM), copper chloride (0.5 mL 20 mM), ascorbic acid (1.0 mL 0.3 M), 320.0 mg of hexadecyltrimethylammonium bromide and 4.3 mL of ultrapure water into a 30 mL reaction bottle and mix them evenly by slight ultrasound; heat in an oil bath and keep warm at 95 ° C for 45 min; after naturally cooling to room temperature, take 3 mL of the mixture, centrifuge at 13500 r / min to collect the product, and wash the resulting solid sample twice with ultrapure water to obtain PdPtCu nanoflowers.

[0172] (2) Using PdPtCu nanoflowers as seeds, PdPtCuPbBi three-dimensional nanoflowers were prepared

[0173] The PdPtCu nanoflowers obtained after centrifugal washing of 3 mL of the mixture in step (1) were dispersed in a mixed solution of 4.0 mL of NN dimethylacetamide and 2.0 mL of ethylene glycol, 30.0 mg of polyvinyl pyrrolidone, 0.8 mg of lead acetylacetonate, 5.0 mg of ascorbic acid, and 2.0 mg of bismuth decanoate were weighed and added to the mixed solution, and the solution was mixed evenly by ultrasonic treatment; nitrogen was introduced for 10 minutes, and then the bottle was covered and vigorously stirred in an oil bath at 160°C for 10 hours, and naturally cooled to room temperature; the mixture was collected by centrifugation at 13500 r / min, and the obtained solid sample was washed twice with ethanol to obtain PdPtCuPbBi three-dimensional nanoflowers, whose TEM image is shown as follows: Figure 2 shown.

[0174] Example 5

[0175] The PdPtCu nanosheets obtained after centrifugal washing of 1 mL of the mixture in step (1) of Example 3 were dispersed in a mixed solution of 4.0 mL of NN-dimethylacetamide and 2.0 mL of ethylene glycol, and then 30.0 mg of polyvinyl pyrrolidone, 5.0 mg of ascorbic acid, 0.8 mg of lead acetylacetonate, and 0.7 mg of antimony trichloride were added. The mixture was ultrasonically treated for 2 h; nitrogen was introduced for 10 min, and the bottle was capped and vigorously stirred in an oil bath at 160°C for 6 h; the mixture was naturally cooled to room temperature; and the mixture was collected by centrifugation at 13500 r / min. The resulting solid was washed twice with ethanol to prepare PdPtCuPbSb UNRs.

[0176] Example 6

[0177] The PdPtCu nanosheets obtained after centrifugal washing of 1 mL of the mixture in step (1) of Example 3 were dispersed in a mixed solution of 4.0 mL of NN-dimethylacetamide and 2.0 mL of ethylene glycol, and then 30.0 mg of polyvinyl pyrrolidone, 5.0 mg of ascorbic acid, 0.7 mg of antimony trichloride, and 1.0 mg of bismuth decanoate were added. The mixture was ultrasonically treated for 2 h; nitrogen was introduced for 10 min, and the bottle was capped and vigorously stirred in an oil bath at 140°C for 16 h; the mixture was naturally cooled to room temperature; and the mixture was collected by centrifugation at 13500 r / min. The resulting solid was washed twice with ethanol to prepare PdPtCuBiSb UNRs.

[0178] Example 7

[0179] The PdPtCu nanosheets obtained after centrifugal washing of 1 mL of the mixture in step (1) of Example 3 were dispersed in a mixed solution of 4.0 mL of oleylamine and 2.0 mL of benzyl alcohol, and then 30.0 mg of polyvinyl pyrrolidone, 5.0 mg of ascorbic acid, 0.4 mg of stannous chloride, and 0.8 mg of lead acetylacetonate were added, and ultrasonic treatment was performed for 2 h; nitrogen was introduced for 10 min, and then the bottle was capped and vigorously stirred in an oil bath at 160°C for 8 h, and then the temperature was further increased to 180°C and stirred for 2 h; the mixture was naturally cooled to room temperature; and the mixture was collected by centrifugation at 13500 r / min. The resulting solid was washed twice with ethanol to prepare PdPtCuPbSn UNRs.

[0180] Example 8

[0181] The PdPtCu nanosheets obtained after centrifugal washing of 1 mL of the mixture in step (1) of Example 3 were dispersed in a mixed solution of 4.0 mL of oleylamine and 2.0 mL of ethylene glycol, and then 30.0 mg of polyvinyl pyrrolidone, 5.0 mg of ascorbic acid, 1.2 mg of ammonium hexafluorogermanate, and 0.5 mg of silver nitrate were added, and ultrasonic treatment was performed for 2 h; nitrogen was introduced for 10 min, and then the bottle was capped and vigorously stirred in an oil bath at 180°C for 5 h; naturally cooled to room temperature; and collected by centrifugation at 13500 r / min. The resulting solid was washed twice with ethanol to prepare PdPtCuAgGe UNRs.

[0182] Example 9

[0183] The PdPtCu nanosheets obtained after centrifugal washing of 1 mL of the mixture in step (1) of Example 3 were dispersed in a mixed solution of 4.0 mL of NN-dimethylacetamide and 2.0 mL of ethylene glycol, and then 30.0 mg of polyvinyl pyrrolidone, 5.0 mg of ascorbic acid, 0.8 mg of lead acetylacetonate, 1.0 mg of bismuth decanoate, and 0.7 mg of antimony trichloride were added. The mixture was ultrasonically treated for 2 h; nitrogen was introduced for 10 min, and the bottle was then capped and vigorously stirred in an oil bath at 160°C for 6 h; the mixture was naturally cooled to room temperature; and the mixture was collected by centrifugation at 13500 r / min. The resulting solid was washed twice with ethanol to prepare PdPtCuPbBiSb UNRs.

[0184] Example 10

[0185] Preparation of PdPtFeSnSb UNRs

[0186] (1) Preparation of PdPtFe NSs

[0187] 12.0 mg of palladium acetylacetonate, 14.0 mg of platinum acetylacetonate, 21.6 mg of ferric acetylacetonate, 90.0 mg of citric acid monohydrate, 30.0 mg of potassium bromide, 30.0 mg of polyvinylpyrrolidone and 10.0 mL of NN dimethylformamide were weighed and added to a 30 mL sample bottle and stirred for 1 hour; 75.0 mg of molybdenum hexacarbonyl was added to the solution, heated in an oil bath and kept at 80°C for 3 hours, then heated to 150°C and kept for 6 hours; after naturally cooling to room temperature, 1 mL of the mixture was taken and collected by centrifugation at 13500 r / min. The resulting solid was washed twice with ethanol to obtain PdPtFe nanosheets.

[0188] (2) Using PdPtFe nanosheets as seeds, PdPtFeSnSb two-dimensional ultrathin nanorings were prepared

[0189] The PdPtFe nanosheets obtained after centrifugal washing of 1 mL of the mixture in step (1) were dispersed in a mixed solution of 4.0 mL of oleylamine and 2.0 mL of benzyl alcohol, and then 30.0 mg of polyvinyl pyrrolidone, 5.0 mg of ascorbic acid, 0.7 mg of stannous chloride, and 0.8 mg of antimony trichloride were added, and ultrasonic treatment was performed for 2 h; nitrogen was introduced for 10 min, and then the bottle was capped and vigorously stirred in an oil bath at 180° C. for 6 h; naturally cooled to room temperature; and centrifuged at 13500 r / min to obtain the obtained solid, which was washed twice with ethanol to obtain PdPtFeSnSb two-dimensional ultrathin nanorings.

[0190] Example 11

[0191] Preparation of PdPtCoSnSb UNRs

[0192] (1) Preparation of PdPtCo NSs

[0193] 14.0 mg of palladium acetylacetonate, 14.0 mg of platinum acetylacetonate, 20.4 mg of cobalt acetylacetonate, 90.0 mg of citric acid monohydrate, 30.0 mg of potassium bromide, 30.0 mg of polyvinylpyrrolidone and 10.0 mL of NN dimethylformamide were weighed and added to a 30 mL sample bottle and stirred for 1 hour; 75.0 mg of molybdenum hexacarbonyl was added to the solution, heated in an oil bath and kept at 80°C for 3 hours, then heated to 150°C and kept for 6 hours; after cooling naturally to room temperature, 1 mL of the mixture was taken and collected by centrifugation at 13500 r / min. The resulting solid was washed twice with ethanol to obtain PdPtCo nanosheets.

[0194] (2) Using PdPtCo nanosheets as seeds, PdPtCoSnSb two-dimensional ultrathin nanorings were prepared

[0195] The PdPtCo nanosheets obtained after centrifugal washing of 2 mL of the mixture in step (1) were dispersed in a mixed solution of 4.0 mL of oleylamine and 2.0 mL of benzyl alcohol, and then 30.0 mg of polyvinyl pyrrolidone, 5.0 mg of ascorbic acid, 0.7 mg of stannous chloride, and 0.8 mg of antimony trichloride were added, and ultrasonic treatment was performed for 2 h; nitrogen was introduced for 10 min, and then the bottle was capped and vigorously stirred in an oil bath at 180° C. for 6 h; naturally cooled to room temperature; and centrifuged at 13500 r / min to obtain a PdPtCoSnSb two-dimensional ultrathin nanoring. The obtained solid was washed twice with ethanol to obtain the PdPtCoSnSb two-dimensional ultrathin nanoring.

[0196] Example 12

[0197] Preparation of PdPtNiSnSb UNRs

[0198] (1) Preparation of PdPtNi NSs

[0199] 12.0 mg of palladium acetylacetonate, 12.0 mg of platinum acetylacetonate, 14.7 mg of nickel acetylacetonate, 90.0 mg of citric acid monohydrate, 30.0 mg of potassium bromide, 30.0 mg of polyvinylpyrrolidone and 10.0 mL of NN dimethylformamide were weighed and added to a 30 mL sample bottle and stirred for 1 hour; 75.0 mg of molybdenum hexacarbonyl was added to the solution, heated in an oil bath and kept at 80°C for 3 hours, then heated to 150°C and kept for 6 hours; after naturally cooling to room temperature, 1 mL of the mixture was taken and collected by centrifugation at 13500 r / min. The resulting solid was washed twice with ethanol to obtain PdPtNi nanosheets.

[0200] (2) Using PdPtNi nanosheets as seeds, PdPtNiSnSb two-dimensional ultrathin nanorings were prepared

[0201] The PdPtNi nanosheets obtained after centrifugal washing of 1 mL of the mixture in step (1) were dispersed in a mixed solution of 4.0 mL of oleylamine and 2.0 mL of benzyl alcohol, and then 30.0 mg of polyvinyl pyrrolidone, 5.0 mg of ascorbic acid, 0.7 mg of stannous chloride, and 0.8 mg of antimony trichloride were added, and ultrasonic treatment was performed for 2 h; nitrogen was introduced for 10 min, and then the bottle was capped and vigorously stirred in an oil bath at 180°C for 6 h; naturally cooled to room temperature; centrifuged at 13500 r / min, and the resulting solid was washed twice with ethanol to obtain PdPtNiSnSb two-dimensional ultrathin nanorings.

[0202] Comparative Example 1

[0203] 16 mg of palladium acetylacetonate, 16.0 mg of platinum acetylacetonate, 15 mg of copper acetylacetonate, 20 mg of bismuth decanoate, 8 mg of lead acetylacetonate, 90.0 mg of citric acid monohydrate, 30.0 mg of potassium bromide, 30.0 mg of polyvinylpyrrolidone and 10.0 mL of NN dimethylformamide were added to a 30 mL sample bottle and stirred for 1 hour; 75.0 mg of molybdenum hexacarbonyl was added to the solution, heated in an oil bath and kept at 80°C for 3 hours, then heated to 150°C and kept for 6 hours; after cooling naturally to room temperature, 1 mL of the mixture was taken and collected by centrifugation at 13500 r / min. The obtained solid was washed twice with ethanol to obtain PdPtCuPbBi particles, whose TEM image is shown as follows. Figure 5 shown.

[0204] Comparative Example 2

[0205] by Figure 6The Pd nanosheets shown are seeds. 1 mL of Pd nanosheets is dispersed in a mixed solution of 4.0 mL of NN-dimethylacetamide and 2.0 mL of ethylene glycol. Then, 60.0 mg of polyvinyl pyrrolidone, 5.0 mg of ascorbic acid, 1.6 mg of platinum acetylacetonate, 1.5 mg of copper acetylacetonate, 0.8 mg of lead acetylacetonate, and 2 mg of bismuth decanoate are added and ultrasonically treated for 2 h. Nitrogen is introduced for 10 min, and then the bottle is capped and vigorously stirred in an oil bath at 160°C for 10 h. The solution is naturally cooled to room temperature and collected by centrifugation at 13500 r / min. The obtained solid is washed twice with ethanol. The TEM image of the obtained substance is shown in FIG. Figure 7 As shown. Figure 7 It can be seen that the PdPtCuBiPb synthesized in Comparative Example 2 does not present the previous nanosheet morphology, but a particle morphology, and the substrate contains oxide.

[0206] ICP-MS testing

[0207] The element content of the nanomaterials prepared in step (1) of each embodiment, the high entropy alloys prepared in step (2) of each embodiment, and the high entropy alloys prepared in comparative example 1 were analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES). The atomic percentage of each element in the nanomaterials prepared in step (1) of each embodiment is shown in Table 1, and the atomic percentage of each element in the high entropy alloys prepared in step (2) of each embodiment and the high entropy alloys prepared in comparative example 1 is shown in Table 2:

[0208] Table 1

[0209]

[0210] Table 2

[0211]

[0212]

[0213] The PdPtCuPbBi UNRs prepared in Example 3 were subjected to XRD test, and the XRD spectrum was as follows: Figure 8 shown.

[0214] from Figure 8 It can be seen that there are four main diffraction peaks at 40.5°, 47.2°, 68.8° and 83.2°, which correspond to the (111), (200), (220) and (311) planes of the face-centered cubic (fcc) phase, respectively, that is, a single fcc phase structure was synthesized.

[0215] The PdPtCuPbBi UNRs prepared in Example 3 were tested by XPS. The XPS spectrum is shown in FIG. Figure 9As shown, it indicates the presence of Pd, Pt, Cu, Bi, and Pb elements in PdPtCuPbBi UNRs.

[0216] The PdPtCuPbBi UNRs prepared in Example 3 were subjected to EDS elemental analysis. Figure 10 As shown. Figure 10 It can be seen that in PdPtCuPbBi UNRs, Pd, Pt, Cu, Bi, and Pb are evenly distributed throughout the nanoring.

[0217] Combine Figure 8 、 Figure 9 and Figure 10 and ICP-MS tests, which jointly proved the successful synthesis of single-phase high-entropy PdPtCuBiPb UNRs.

[0218] From Table 1, Table 2 and Figures 1 to 10 It can be concluded that the high entropy alloys obtained in the embodiments of the present application have controllable morphology, adjustable components, and wide applicability; whereas the comparative examples cannot obtain nanoring or nanoflower morphology, and the high entropy alloys obtained are in the form of agglomerated particles.

[0219] The PdPtCu NSs prepared in step (1) of Example 3, the high entropy alloys prepared in various Examples and Comparative Examples, and commercial Pd / C catalysts (10 wt.% of Pd, purchased from Sigma-Aldrich Shanghai Trading Co., Ltd.) and Pt / C catalysts (20 wt.% of Pt, purchased from Johnson Matthey (JM)) were subjected to electrocatalytic ethanol oxidation tests and stability tests, respectively. The specific steps are as follows:

[0220] Sample preparation: Taking the PdPtCuBiPb UNRs in Example 3 as an example, before the electrocatalytic performance test, the prepared PdPtCuBiPb UNRs were loaded on carbon black and the catalyst solution was prepared: 0.4 mg Pd+Pt PdPtCuBiPb UNRs were dissolved in 4.0 mL of ethanol solution, 1.6 mg of carbon black was weighed and ultrasonically dispersed with 2.0 mL of ethanol solution, and then PdPtCuBiPb UNRs were slowly added dropwise to the carbon black solution and ultrasonically treated for 2 hours. PdPtCuBiPb UNRs / C was then collected and washed with ethanol by centrifugation 5 times (13500 r / min, 5 min). The catalyst was redispersed in a mixture containing 0.995 mL of ethanol and 0.005 mL of Nafion (5 wt%) and ultrasonicated for 1 hour to form a well-mixed catalyst. Commercial Pd / C and Pt / C were both configured to 0.4 mg. Pd / mL, 0.4mg Pt / mL. Finally, 10 μL of the prepared catalyst was dropped onto the glassy carbon electrode (GCE, 0.196 cm 2 ).

[0221] Test conditions and procedures: Electrochemical measurements were performed on a CHI760E using a glassy carbon electrode as the working electrode, a Hg / HgO electrode as the reference electrode, and a platinum wire as the counter electrode. All test potentials were converted to a reversible hydrogen electrode (RHE) as a reference. Measurements were performed in solutions containing 1 M KOH and 1 M C2H5OH at a scan rate of 50 mV·s. -1 , potential range is 0-1.325V RHE , the stability test fixed potential is 0.725V.

[0222] The electrocatalytic ethanol oxidation test results of the high entropy alloys prepared in Example 1, Example 2 and Example 4 are shown in the figure. Figure 11 As shown in the figure, the electrocatalytic ethanol oxidation test results of PdPtCu NSs / C, PdPtCuPbBi UNRs / C, Pd / C and Pt / C catalysts prepared in Example 3 are as follows: Figure 12 shown.

[0223] from Figure 11 It can be seen that the peak potential of PdPtCuBiPb NPs / C is 6.1A mg -1 Pd+Pt , 0.45V RHE When 0.06A mg -1 Pd+Pt , 0.6V RHE When 0.54A mg -1 Pd+Pt ; PdPtCuBiPb NWs / C has a peak potential of 8.6A mg -1 Pd+Pt , 0.45V RHE When 0.40A mg -1 Pd+Pt , 0.6V RHE 2.14Amg -1 Pd+Pt ; PdPtCuBiPb NDs / C has a peak potential of 9.6A mg -1 Pd+Pt , 0.45V RHE When 0.54A mg -1 Pd+Pt , 0.6V RHE When 2.74A mg -1 Pd+Pt .

[0224] from Figure 12It can be seen that the initial oxidation potential of PdPtCuPbBi UNRs / C prepared by using the high entropy alloy of Example 3 is lower than that of commercial Pd / C and Pt / C catalysts by 261mV and 234mV respectively; RHE 1.94Amg -1 Pd+Pt , which are 17.2, 5.2 and 4.3 times that of PdPtCu NSs / C, commercial Pd / C and Pt / C catalysts respectively; PdPtCuPbBiUNRs / C at 0.6V RHE 6.67Amg -1 Pd+Pt , which are 24.8, 23.4 and 25.6 times that of PdPtCu NSs / C, commercial Pd / C and Pt / C catalysts, respectively; the peak potential of PdPtCuPbBi UNRs / C is 18.21A mg -1 Pd+Pt , which are 35.4, 13.1 and 16.3 times that of PdPtCu NSs / C, commercial Pd / C and Pt / C catalysts, respectively.

[0225] The electrocatalytic ethanol oxidation test results of the high entropy alloys prepared in Comparative Example 1 and Comparative Example 2 are shown in FIG. Figure 13 As shown; wherein, the comparative example 1 is 9.09A mg at the peak potential -1 Pd+Pt , 0.45V RHE 0.62Amg -1 Pd+Pt , 0.6V RHE 2.74Amg -1 Pd+Pt ; Comparative Example 2 at peak potential is 8.56A mg -1 Pd+Pt , 0.45V RHE When 0.48A mg -1 Pd+Pt , 0.6V RHE When 2.45A mg -1 Pd+Pt .

[0226] That is, the high entropy alloy prepared in the embodiment has good catalytic performance.

[0227] The stability test results are as follows Figure 14 As shown, from Figure 14 It can be seen that after 20000s stability test, the EOR activity of PdPtCuPbBi UNRs / C can still be maintained at 2.56A mg -1 Pd+Pt, which is much better than the stability performance of PdPtCu NSs / C, commercial Pd / C and Pt / C catalysts.

[0228] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0229] The embodiments described above only express several implementation methods of the present application, which are convenient for understanding the technical solutions of the present application in a specific and detailed manner, but they cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several variations and improvements can be made, which all fall within the scope of protection of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the scope of protection of the claims attached to the present application. Therefore, the scope of protection of the patent of this application shall be based on the content of the attached claims, and the description and drawings can be used to interpret the content of the claims.

Claims

1. A high entropy alloy, characterized in that The high entropy alloy comprises at least five metal elements, and the high entropy alloy has a morphological feature of a two-dimensional nanoring or a three-dimensional nanoflower; The method for preparing the high entropy alloy comprises the following steps: A nanomaterial is mixed with a metal salt precursor, a surfactant, a reducing agent and a solvent to perform an oxidation-reduction reaction, and the nanomaterial is used as a seed crystal to generate a high-entropy alloy having a morphology corresponding to the morphology of the nanomaterial; the nanomaterial contains 2 to 4 metal elements M; the metal salt precursor contains at least one metal element N, the metal element N is different from the metal element M, and the sum of the types of the metal elements M in the nanomaterial and the metal elements N in the metal salt precursor is not less than 5.

2. The high entropy alloy according to claim 1, wherein The metal elements are selected from at least five of p-block metal elements, d-block metal elements, and ds-block metal elements.

3. The high entropy alloy according to claim 1, wherein The metal element includes at least one of the following characteristics (1) to (3): (1) The metal elements are at least five selected from Ru, Rh, Au, Ir, Pd, Pt, Ag, Cu, Fe, Co, Ni, Pb, Bi, Sn, Sb and Ge; (2) The metal elements include at least Pd and Pt; (3) The molar ratio of each metal element is 5% to 35%.

4. The high entropy alloy according to claim 1, wherein The high entropy alloy is selected from one of palladium-platinum-copper-lead-bismuth alloy, palladium-platinum-copper-lead-antimony alloy, palladium-platinum-copper-bismuth-antimony alloy, palladium-platinum-copper-lead-bismuth-antimony alloy, palladium-platinum-iron-tin-antimony alloy, palladium-platinum-nickel-tin-antimony alloy, palladium-platinum-cobalt-tin-antimony alloy, palladium-platinum-copper-lead-tin alloy and palladium-platinum-copper-silver-germanium alloy.

5. The high entropy alloy according to claim 1 or 4, wherein: The high entropy alloy is a PdPtCuPbBi two-dimensional nanoring, a PdPtCuPbSb two-dimensional nanoring, a PdPtCuBiSb two-dimensional nanoring, a PdPtCuPbBiSb two-dimensional nanoring, a PdPtFeSnSb two-dimensional nanoring, a PdPtNiSnSb two-dimensional nanoring, a PdPtCoSnSb two-dimensional nanoring, a PdPtCuPbSn two-dimensional nanoring, a PdPtCuAgGe two-dimensional nanoring or a PdPtCuPbBi three-dimensional nanoflower.

6. A method for preparing a high entropy alloy, characterized in that: The following steps are involved: A nanomaterial is mixed with a metal salt precursor, a surfactant, a reducing agent and a solvent to perform an oxidation-reduction reaction, and the nanomaterial is used as a seed crystal to generate a high-entropy alloy having a morphology corresponding to the morphology of the nanomaterial; the nanomaterial contains 2 to 4 metal elements M; the metal salt precursor contains at least one metal element N, the metal element N is different from the metal element M, and the sum of the types of the metal elements M in the nanomaterial and the metal elements N in the metal salt precursor is not less than 5.

7. The method for preparing a high entropy alloy according to claim 6, wherein: The morphology of the nanomaterial is selected from one of zero-dimensional nanoparticles, one-dimensional nanowires, two-dimensional nanosheets, two-dimensional nanorings and three-dimensional nanoflowers, and the morphology of the high-entropy alloy corresponds to zero-dimensional nanoparticles, one-dimensional nanowires, two-dimensional nanorings, two-dimensional nanorings and three-dimensional nanoflowers, respectively.

8. The method for preparing a high entropy alloy according to claim 6, wherein: The nanomaterial is selected from one of PdPtCu zero-dimensional nanoparticles, PdPtCu one-dimensional nanowires, PdPtCu two-dimensional nanosheets, PdPtFe two-dimensional nanosheets, PdPtCo two-dimensional nanosheets, PdPtNi two-dimensional nanosheets and PdPtCu three-dimensional nanoflowers.

9. The method for preparing a high entropy alloy according to any one of claims 6 to 8, wherein: The preparation method includes at least one of the following features (6) to (11): (6) The metal salt precursor is selected from at least one of chlorate, sodium chlorate, potassium chlorate, acetylacetonate, nitrate, chloride and decanoate of the metal element in the metal salt precursor; (7) The surfactant is polyvinylpyrrolidone; (8) The reducing agent is selected from at least one of ascorbic acid, potassium bromide and citric acid monohydrate; (9) The solvent is selected from at least one of N-N-dimethylacetamide, ethylene glycol, oleylamine, benzyl alcohol and water; (10) The temperature of the redox reaction is 140°C to 180°C; (11) The redox reaction is carried out under a protective atmosphere, and the protective atmosphere is selected from at least one of nitrogen and an inert gas.

10. A membrane electrode assembly, characterized in that: The invention comprises a proton exchange membrane and a catalytic layer, wherein the catalytic layer is arranged on both sides of the proton exchange membrane, and at least one of the catalytic layers comprises the high entropy alloy according to any one of claims 1 to 5 or the high entropy alloy prepared by the preparation method according to any one of claims 6 to 9.

11. A fuel cell, characterized in that: The membrane electrode assembly according to claim 10 is included.

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