Heterostructure nanoparticles as well as preparation method and application thereof

Abstract

The invention provides heterostructure nanoparticles as well as a preparation method and application thereof. The present invention relates to a method for preparing heterostructure nanoparticles, the heterostructure nanoparticles comprising a first phase and a second phase in contact with each other, the first phase being an alloy comprising a platinum element, a nickel element and optionally a phosphorus element, the second phase comprising nickel phosphide, the method comprising the steps of reacting a platinum precursor and a first nickel precursor in the presence of a reducing agent, alloy nanoparticles containing platinum and nickel elements are obtained; and adding a second nickel precursor and a phosphorus source into the alloy nanoparticles for reaction, and separating a reaction product to obtain the heterostructure nanoparticles. The heterostructure nanoparticles provided by the invention can improve the overall catalytic activity of the catalyst. The heterostructure nanoparticles can be used as a low-cost and high-efficiency novel catalyst to solve the problems that Pt catalysts in the fields of fuel cells, zinc-air cells, electrolyzed water and the like are high in price and Pt is prone to poisoning and inactivation.

Description

Technical Field

[0001] The present application belongs to the field of nanomaterial technology, and specifically relates to heterogeneous structure nanoparticles and their preparation method and application. Background Art

[0002] Because their d-orbital electrons are not fully filled, precious metal materials readily adsorb reactants as catalytic materials with moderate adsorption strength, resulting in high catalytic activity. Furthermore, they possess excellent properties such as high-temperature resistance, corrosion resistance, and good stability, making them widely used in various catalytic fields. Platinum (Pt), a typical precious metal material, is frequently used as a catalyst in new energy, chemical, pharmaceutical, oil refining, and automobile exhaust purification. However, due to its limited reserves on Earth and the difficulty of refining, Pt is expensive to use as a catalyst. Summary of the Invention

[0003] In response to the problems of the existing technology such as the small reserves of precious metal Pt and the high price of using it as a catalyst, the present application provides a heterostructured nanoparticle and its preparation method and application.

[0004] Specifically, this application involves the following aspects:

[0005] A method for preparing heterostructured nanoparticles, wherein the heterostructured nanoparticles comprise a first phase and a second phase in contact with each other, the first phase being an alloy comprising platinum, nickel, and optionally phosphorus, and the second phase comprising nickel phosphide, the method comprising the following steps:

[0006] reacting a platinum precursor and a first nickel precursor in the presence of a reducing agent to obtain alloy nanoparticles containing platinum and nickel elements;

[0007] A second nickel precursor and a phosphorus source are added to the alloy nanoparticles to react and the reaction product is separated to obtain heterogeneous structure nanoparticles.

[0008] Optionally, the molar ratio of the platinum element in the platinum precursor to the nickel element in the first nickel precursor is 1:2-10:1.

[0009] Optionally, reacting the platinum precursor and the first nickel precursor in the presence of a reducing agent comprises the following steps:

[0010] reacting a platinum precursor and a first nickel precursor in the presence of a reducing agent at a temperature of 50-200° C. for 0.5-3 h;

[0011] Then, the temperature is raised to 100-300° C. and the reaction is carried out for 0.5-5 hours to obtain alloy nanoparticles containing platinum and nickel elements.

[0012] Optionally, the molar ratio of the platinum element in the platinum precursor to the nickel element in the second nickel precursor is 1:5-1:1.

[0013] Optionally, the molar ratio of the second nickel precursor to the phosphorus source is 1:5-1:40.

[0014] Optionally, the platinum precursor is selected from one or more of a platinum complex, chloroplatinic acid, chloroplatinate, and an organic acid salt of platinum.

[0015] Optionally, the first nickel precursor and the second nickel precursor are independently selected from one or more of nickel complexes, nickel organic acid salts, and nickel inorganic acid salts.

[0016] Optionally, the reducing agent is an organic amine.

[0017] Optionally, the phosphorus source is an organic phosphorus.

[0018] Optionally, the first phase comprises spherical or hemispherical nanospheres, and the second phase comprises nanorods.

[0019] A heterostructured nanoparticle comprises a first phase and a second phase in contact with each other, wherein the first phase is an alloy comprising platinum, nickel and optionally phosphorus, and the second phase comprises nickel phosphide.

[0020] Optionally, the first phase comprises spherical or hemispherical nanospheres, and the second phase comprises nanorods.

[0021] Optionally, the nanospheres have an average diameter of 6-18 nm.

[0022] Optionally, the nanorods have an average length of 10-40 nm and an average width of 4-7 nm.

[0023] Optionally, the nanoparticles are prepared by any one of the above preparation methods.

[0024] Use of any of the above-mentioned nanoparticles as a catalyst in a catalytic reaction.

[0025] Application of any of the above nanoparticles as a catalyst in fuel cells, zinc-air batteries or water electrolysis.

[0026] The heterostructured nanoparticles described in this application reduce the amount of Pt required by forming alloy nanospheres with the transition metal Ni. Furthermore, the transition metal phosphide nanorods (nickel phosphide, NiP) and PtNi nanospheres are connected to form a heterostructure, which not only utilizes the catalytically active sites of the nickel phosphide but also utilizes electronic coupling between the heterostructures to enhance the overall catalytic activity of the catalyst.

[0027] The heterostructured nanoparticles of the present application can be used as a low-cost, high-efficiency new catalyst to solve the problems of high prices of Pt catalysts and easy poisoning and deactivation of Pt in the fields of fuel cells, zinc-air batteries, and water electrolysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a high-resolution transmission electron microscopy image of the heterostructured nanoparticles in this application;

[0029] Figure 2 This is a low-resolution transmission electron microscopy image of the heterostructured nanoparticles in this application;

[0030] Figure 3 This is a scanning diagram of element distribution of heterostructured nanoparticles in this application;

[0031] Figure 4 This is a transmission electron microscopy image of the nanoparticles prepared in Comparative Example 1;

[0032] Figure 5 This is a transmission electron microscopy image of the Pt-Ni-P nanoparticles prepared in Comparative Example 2;

[0033] Figure 6 TEM image of PtNi nanoparticles prepared in Comparative Example 3;

[0034] Figure 7 TEM image of NiP nanoparticles prepared in Comparative Example 4;

[0035] Figure 8 This is a test diagram of oxygen evolution reaction performance;

[0036] Figure 9 This is a performance test diagram of a methanol fuel cell. DETAILED DESCRIPTION

[0037] The present application is further described below with reference to examples. It should be understood that the examples are only used to further illustrate and explain the present application and are not intended to limit the present application.

[0038] Unless otherwise defined, technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art. Although methods and materials similar or identical to those described herein may be used in experiments or practical applications, the materials and methods are described herein below. In the event of a conflict, the present specification, including definitions, will prevail. In addition, the materials, methods, and examples are provided for illustrative purposes only and are not intended to be limiting. The present application is further described below with reference to specific examples, which are not intended to limit the scope of this application.

[0039] In the present application, a heterostructure refers to a structure formed by two materials of different compositions contacting each other, with an interface region formed by the two phases contacting each other.

[0040] Nanoparticle refers to a particle with a single crystalline phase and a maximum diameter of 1-1000 nanometer. The shape can be spherical, hemispherical, rod-shaped, triangular, polygonal, etc. Those skilled in the art will appreciate that spherical, hemispherical, rod-shaped, triangular, polygonal can be regular spherical, hemispherical, rod-shaped, triangular, polygonal, or can be irregular or approximate spherical, hemispherical, rod-shaped, triangular, polygonal. Nanosphere refers to a nanoparticle that is spherical or hemispherical in overall shape. Nanorod refers to a nanoparticle that is rod-shaped in overall shape.

[0041] To address the problems of the prior art, the present application provides a method for preparing heterostructured nanoparticles, wherein the heterostructured nanoparticles comprise a first phase and a second phase in contact with each other, wherein the first phase is an alloy comprising platinum, nickel, and optionally phosphorus, and the second phase comprises nickel phosphide. The first phase being an alloy comprising platinum, nickel, and optionally phosphorus means that the first phase can be an alloy comprising platinum and nickel, or an alloy comprising platinum, nickel, and phosphorus.

[0042] In a specific embodiment, the first phase comprises spherical or hemispherical nanospheres, and the second phase comprises nanorods.

[0043] Specifically, the preparation method comprises the following steps:

[0044] S1: reacting a platinum precursor and a first nickel precursor in the presence of a reducing agent to obtain alloy nanoparticles containing platinum and nickel elements;

[0045] S2: Add a second nickel precursor and a phosphorus source to the alloy nanoparticles to react and separate the reaction products to obtain heterostructured nanoparticles, which may also be referred to as PtNi / NiP heterostructured nanoparticles in this application. The chemical formula of PtNi / NiP does not exclude that the prepared heterostructured nanoparticles also contain a small amount of other elements.

[0046] It can be seen that step S1 is used to obtain alloy nanoparticles containing platinum and nickel elements, while step S2 is used to generate nickel phosphide on the basis of the alloy nanoparticles to form heterostructured nanoparticles.

[0047] In step S1, the platinum precursor may be a platinum complex, chloroplatinic acid, chloroplatinate, or an organic acid salt of platinum, etc. The platinum complex, chloroplatinic acid, chloroplatinate, or an organic acid salt of platinum may be any platinum complex, chloroplatinic acid, chloroplatinate, or organic acid salt of platinum known in the art.

[0048] In a specific embodiment, the platinum precursor can be selected from one or more of trimethylcyclopentadienylplatinum, dinitrosodiammineplatinum, ammonium hexachloroplatinate, chloroplatinic acid, potassium chloroplatinate, platinum acetylacetonate, and platinum acetate.

[0049] The nickel precursor may be a nickel complex, nickel organic acid salt, nickel inorganic acid salt, etc. The nickel complex, nickel organic acid salt, nickel inorganic acid salt may be any platinum complex, chloroplatinic acid, chloroplatinate, platinum organic acid salt known in the art.

[0050] In a specific embodiment, the nickel precursor can be selected from one or more of nickel chloride, nickel acetylacetonate, nickel acetate, 2,2-bipyridyl nickel chloride, nickel perchlorate, nickel carbonate, nickel naphthenate, and nickel benzoate.

[0051] The reducing agent is an organic amine, wherein the organic amine is any organic amine known in the art.

[0052] In a specific embodiment, the reducing agent can be selected from one or more of dodecylamine, oleylamine, octadecylamine, ethylenediamine, hydrazine, and hydroxylamine.

[0053] The solvent for the reaction in step S1 can be selected from conventional solvents in the art that can dissolve platinum precursors and nickel precursors, such as styrene, trichloroethylene, octadecene, benzene, toluene, xylene, pentane, hexane, dodecane, DMF, NMP, benzyl alcohol, sulfolane, diphenyl ether, etc.

[0054] In order to fully form alloy nanoparticles containing platinum and nickel elements, it is necessary to control the ratio of the platinum element in the platinum precursor to the nickel element in the first nickel precursor.

[0055] In a specific embodiment, the molar ratio of the platinum element in the platinum precursor to the nickel element in the first nickel precursor is 1:2-10:1, for example, it can be 1:2, 1.5:2, 1:1, 1.5:1, 2:1, 2.5:1, 3.0:1, 3.5:1, 4.0:1, 4.5:1, 5.0:1, 6.0:1, 7.0:1, 8.0:1, 9.0:1, 10.0:1 and any value therebetween.

[0056] Step S1 may further include the following steps:

[0057] S11: reacting a platinum precursor and a first nickel precursor in the presence of a reducing agent at a temperature of 50-200° C. for 0.5-3 h;

[0058] S12: then raising the temperature to 100-300° C. and reacting for 0.5-5 hours to obtain alloy nanoparticles containing platinum and nickel elements.

[0059] Wherein, the reaction temperature in S11 is 50-200°C, for example, it can be 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, and any value therebetween; the reaction time is 0.5-3h, for example, it can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, and any value therebetween.

[0060] The reaction temperature in S12 is greater than the reaction temperature in S11, and is 100-300°C, for example, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, and any values ​​therebetween; the reaction time is 0.5-5h, for example, 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, and any values ​​therebetween.

[0061] The main purpose of step S11 is to remove impurities and moisture and fully dissolve the platinum precursor and the first nickel precursor in the solvent. For example, the reaction system including the platinum precursor, the first nickel precursor, the reducing agent, and the solvent can be heated to 50-200° C. in the presence of an inert gas. The inert gas used can be an inert gas commonly used in the art, such as nitrogen, argon, or helium.

[0062] Step S12 is to fully generate alloy nanoparticles containing platinum and nickel elements.

[0063] Those skilled in the art will appreciate that, in the reaction of the present application, the reaction system needs to be stirred and condensed under reflux.

[0064] In step S2, similar to the first nickel precursor, the second nickel precursor can be a nickel complex, an organic acid salt of nickel, or an inorganic acid salt of nickel, for example, one or more selected from nickel chloride, nickel acetylacetonate, nickel acetate, 2,2-bipyridyl nickel chloride, nickel perchlorate, nickel carbonate, nickel naphthenate, and nickel benzoate. It will be understood by those skilled in the art that the second nickel precursor can be the same as or different from the first nickel precursor.

[0065] In order to fully form heterogeneous nanoparticles, it is necessary to control the ratio of the platinum element in the platinum precursor to the nickel element in the second nickel precursor.

[0066] In a specific embodiment, the molar ratio of the platinum element in the platinum precursor to the nickel element in the second nickel precursor is 1:5-1:1, for example, 1:5, 1.1:5, 1.2:5, 1.3:5, 1.4:5, 1.5:5, 1.6:5, 1.7:5, 1.8:5, 1.9:5, 2:5, 2.1:5, 2.2:5, 2.3:5, 2.4:5, 2.5:5, 2.6:5 , 2.7:5, 2.8:5, 2.9:5, 3:5, 3.1:5, 3.2:5, 3.3:5, 3.4:5, 3.5:5, 3.6:5, 3.7:5, 3.8:5, 3.9:5, 2:5, 4.1:5, 4.2:5, 4.3:5, 4.4:5, 4.5:5, 4.6:5, 4.7:5, 4.8:5, 4.9:5, 1:1, and any value in between.

[0067] The phosphorus source is organic phosphorus, and can be a common phosphorus source in the art.

[0068] In a specific embodiment, the phosphorus source can be selected from one or more of tri-n-octyl phosphine, triphenyl phosphine, triphenyl phosphine chloride, and triphenyl phosphine bromide.

[0069] The amount of the phosphorus source should be sufficient to fully phosphate the second nickel precursor. In a specific embodiment, the molar ratio of the second nickel precursor to the phosphorus source is 1:5-1:40, for example, 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, and any value therebetween.

[0070] In step S2, the temperature for adding the second nickel precursor and the phosphorus source to the alloy nanoparticles containing platinum and nickel elements for reaction can be 100-300°C, for example, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, and any values ​​therebetween.

[0071] The reaction products can be separated using commonly used separation methods in the art. For example, a detergent and a precipitant can be added to the nanoparticle solution obtained after the reaction, and high-speed centrifugation can be performed to obtain heterogeneous nanoparticles. The detergent can be hexane, acetone, cyclohexane, n-pentane, etc. The precipitant can be methanol, ethanol, isopropanol, etc.

[0072] In a specific embodiment, the preparation method of the present application includes the following steps: S1: reacting a platinum precursor and a first nickel precursor in the presence of a reducing agent to obtain alloy nanoparticles containing platinum and nickel elements, wherein the molar ratio of the platinum element in the platinum precursor to the nickel element in the first nickel precursor is 1:2-10:1; S2: adding a second nickel precursor and a phosphorus source to the alloy nanoparticles containing platinum and nickel elements to react and separating the reaction products to obtain heterostructured nanoparticles, wherein the molar ratio of the platinum element in the platinum precursor to the nickel element in the second nickel precursor is 1:5-1:1, and the molar ratio of the second nickel precursor to the phosphorus source is 1:5-1:40.

[0073] In a specific embodiment, the preparation method of the present application includes the following steps: S11: reacting a platinum precursor and a first nickel precursor in the presence of a reducing agent at a temperature of 50-200°C for 0.5-3h; S12: then raising the temperature to 100-300°C and reacting for 0.5-5h to obtain alloy nanoparticles containing platinum and nickel elements, wherein the molar ratio of the platinum element in the platinum precursor to the nickel element in the first nickel precursor is 1:2-10:1; S2: adding a second nickel precursor and a phosphorus source to the alloy nanoparticles containing platinum and nickel elements to react and separating the reaction products to obtain heterostructured nanoparticles, wherein the molar ratio of the platinum element in the platinum precursor to the nickel element in the second nickel precursor is 1:5-1:1, and the molar ratio of the second nickel precursor to the phosphorus source is 1:5-1:40.

[0074] The present application also provides a heterostructured nanoparticle comprising a first phase and a second phase in contact with each other, wherein the first phase is an alloy comprising platinum, nickel, and optionally phosphorus, and the second phase comprises nickel phosphide.

[0075] The first phase is an alloy comprising platinum, nickel, and optionally phosphorus. This means that the first phase can be an alloy comprising platinum and nickel, or an alloy comprising platinum, nickel, and phosphorus. That is, the materials of the nanospheres are entirely or primarily platinum and nickel, and may further include phosphorus. The materials of the nanorods are entirely or primarily nickel and phosphorus.

[0076] In a specific embodiment, the first phase comprises spherical or hemispherical nanospheres, and the second phase comprises nanorods.

[0077] Specifically, the structure of heterostructured nanoparticles is as follows Figure 1 and Figure 2 Those skilled in the art will appreciate that one or more nanorods may be connected to the nanosphere, and the epitaxial growth directions of the nanorods may be in the same direction or in different directions.

[0078] In a specific embodiment, the average diameter of the nanospheres is 6-18 nm, for example, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, and any value therebetween.

[0079] In a specific embodiment, the average length of the nanorods is 10-40nm, for example, it can be 10nm, 11nm, 12nm, 13nm, 14nm, 15nm, 16nm, 17nm, 18nm, 19nm, 20nm, 21nm, 22nm, 23nm, 24nm, 25nm, 26nm, 27nm, 28nm, 29nm, 30nm, 31nm, 32nm, 33nm, 34nm, 35nm, 36nm, 37nm, 38nm, 39nm, 40nm, and any value between these values; the average width is 4-7nm, for example, it can be 4nm, 4.5nm, 5nm, 5.5nm, 6nm, 6.5nm, 7nm, and any value between these values.

[0080] In a specific embodiment, the heterostructured nanoparticles of the present application comprise a first phase and a second phase in contact with each other, wherein the first phase is an alloy comprising platinum, nickel, and optionally phosphorus, and the second phase comprises nickel phosphide. The first phase comprises spherical or hemispherical nanospheres, and the second phase comprises nanorods. The nanorods are made of nickel and phosphorus, the nanospheres have an average diameter of 6-18 nm, the nanorods have an average length of 10-40 nm, and an average width of 4-7 nm.

[0081] In a specific embodiment, the heterostructured nanoparticles of the present application are prepared by any of the above preparation methods.

[0082] The structure of the heterostructured nanoparticles can be characterized by techniques known in the art, such as transmission electron microscopy. Elements such as platinum, nickel, and phosphorus in the heterostructured nanoparticles can also be characterized by techniques known in the art, such as energy dispersive spectroscopy or plasma emission spectroscopy.

[0083] The heterostructured nanoparticles of the present application may be heterostructured only at the material level, or may be heterostructured at both the material and structural levels. On the one hand, at the material level, the nanoparticles comprise a first phase and a second phase in contact with each other, wherein the first phase is an alloy comprising platinum, nickel, and optionally phosphorus, and the second phase comprises nickel phosphide. Furthermore, at the structural level, the nanoparticles may include spherical or hemispherical structures, as well as rod-shaped structures.

[0084] The heterostructured nanoparticles described in this application reduce platinum usage by forming alloy nanospheres with the transition metal nickel. Furthermore, the heterostructure, formed by connecting nanorods containing the transition metal phosphide nickel phosphide with alloy nanospheres containing platinum and nickel, utilizes the catalytically active sites of the nickel phosphide while also enhancing the overall catalytic activity of the catalyst through electronic coupling within the heterostructure.

[0085] The present application also provides the use of any of the above heterogeneous structure nanoparticles as a catalyst in a catalytic reaction.

[0086] The present application also provides the use of any of the above heterostructured nanoparticles as a catalyst in a fuel cell, a zinc-air battery or water electrolysis.

[0087] The heterogeneous structured nanoparticles of the present application can be used as various types of catalysts in the fields of new energy, chemical industry, pharmaceuticals, oil refining, automobile exhaust purification, etc.

[0088] The heterogeneous structured nanoparticles of the present application can be used as a low-cost, high-efficiency new catalyst to solve the problems of high prices of platinum catalysts and easy poisoning and deactivation of platinum in the fields of fuel cells, zinc-air batteries, and water electrolysis.

[0089] Example

[0090] Example 1

[0091] 39.3 mg of platinum acetylacetonate (Pt(acac)2) and 25.7 mg of nickel acetylacetonate (Ni(acac)2) were weighed and placed in a three-necked flask. 12 mL of octadecene and 5 mL of oleylamine were then added. Under high-purity nitrogen gas and magnetic stirring at 1000 rpm, the mixture was refluxed with cooling water. The temperature was first heated to 100°C for 30 minutes, then raised to 180°C for 2 hours.

[0092] Weigh 51.4 mg of nickel acetylacetonate in advance. After the first step of the reaction is completed, quickly add 51.4 mg of nickel acetylacetonate to the reaction system and add 3 mL of tri-n-octylphosphine. React at 180 °C for 30 min, then stop introducing N2 and raise the temperature to 280 °C under sealed conditions for 2 h.

[0093] After the reaction, 15 mL of n-hexane and 30 mL of anhydrous ethanol were added to the solution containing the heterogeneous structured nanoparticles, ultrasonically shaken for 30 minutes, and then centrifuged at a speed of 10,000 rpm / min. Finally, the heterogeneous structured nanoparticles obtained by centrifugation were redispersed in n-hexane solution for storage.

[0094] The transmission electron microscopy images of the obtained heterostructured nanoparticles are shown in Figure 2. Figure 1 、 Figure 2As shown, it can be seen that the synthesized heterogeneous nanoparticles have a heterogeneous structure formed by the contact of spherical particles and rod-shaped particles.

[0095] The element distribution scanning diagram of the obtained heterostructure nanoparticles is shown in Figure 3 As shown in the figure, it can be seen that the nanospheres in the heterostructured nanoparticles mainly contain Pt and Ni elements, while the nanorods mainly contain Ni and P elements. Therefore, it is judged that the nanospheres in the heterostructure are PtNi alloys, and the nanorods are NiP.

[0096] In addition, the element composition of the heterogeneous structure can also be distinguished from the contrast. Elements with large molecular weight appear darker in TEM mode, while elements with small molecular weight appear brighter. Figure 3 It can be observed that the contrast of the nanosphere part is deeper and darker overall, so it is PtNi alloy, while the contrast of the nanorod part is relatively shallow and brighter, so it is phosphide.

[0097] Example 2

[0098] 39.3 mg of platinum acetylacetonate (Pt(acac)2) and 25.7 mg of nickel acetylacetonate (Ni(acac)2) were weighed and placed in a three-necked flask. 12 mL of octadecene and 5 mL of oleylamine were then added. Under high-purity nitrogen gas and magnetic stirring at 1000 rpm, the mixture was refluxed with cooling water. The temperature was first heated to 100°C for 30 minutes, then raised to 230°C for 2 hours.

[0099] Weigh 51.4 mg of nickel acetylacetonate in advance. After the first step reaction time is over, quickly add 51.4 mg of nickel acetylacetonate to the reaction system, and add 3 mL of tri-n-octylphosphine at the same time. React at 180°C for 30 minutes, then stop introducing N2, raise the temperature to 280°C under sealed conditions and react for 2 hours.

[0100] After the reaction, 15 mL of n-hexane and 30 mL of anhydrous ethanol were added to the solution containing the heterogeneous structured nanoparticles, ultrasonically shaken for 30 minutes, and then centrifuged at a speed of 10,000 rpm / min. Finally, the heterogeneous structured nanoparticles obtained by centrifugation were redispersed in n-hexane solution for storage.

[0101] The obtained heterostructured nanoparticles have a heterostructure formed by contact between spherical particles and rod-shaped particles, wherein the nanosphere part is PtNi alloy and the nanorod part is NiP.

[0102] Example 3

[0103] 39.3 mg of platinum acetylacetonate (Pt(acac)2) and 25.7 mg of nickel acetylacetonate (Ni(acac)2) were weighed and placed in a three-necked flask. 12 mL of octadecene and 5 mL of oleylamine were then added. Under high-purity nitrogen gas and magnetic stirring at 1000 rpm, the mixture was refluxed with cooling water. The solution was first heated to 100°C for 30 minutes to remove impurities and moisture while dissolving the platinum and nickel precursors into the organic solution. The temperature was then raised to 180°C for 2 hours.

[0104] Weigh 128.5 mg of nickel acetylacetonate in advance. After the first step of the reaction is completed, quickly add 128.5 mg of nickel acetylacetonate to the reaction system, and add 7.5 mL of tri-n-octylphosphine at the same time. React at 180°C for 30 minutes, then stop introducing N2, and raise the temperature to 310°C under sealed conditions for 2 hours.

[0105] After the reaction, 15 mL of n-hexane and 30 mL of anhydrous ethanol were added to the solution containing the heterogeneous structured nanoparticles, ultrasonically shaken for 30 minutes, and then centrifuged at a speed of 10,000 rpm / min. Finally, the heterogeneous structured nanoparticles obtained by centrifugation were redispersed in n-hexane solution for storage.

[0106] The obtained heterostructured nanoparticles have a heterostructure formed by contact between spherical particles and rod-shaped particles, wherein the nanosphere part is PtNi alloy and the nanorod part is NiP.

[0107] Comparative Example 1

[0108] 13.1 mg of platinum acetylacetonate (Pt(acac)2) and 25.7 mg of nickel acetylacetonate (Ni(acac)2) were weighed and placed in a three-necked flask. 12 mL of octadecene and 5 mL of oleylamine were then added. Under high-purity nitrogen gas and magnetic stirring at 1000 rpm, the mixture was refluxed with cooling water. The temperature was first heated to 100°C for 30 minutes, then raised to 180°C for 2 hours.

[0109] Weigh 51.4 mg of nickel acetylacetonate in advance. After the first step of the reaction is completed, quickly add 51.4 mg of nickel acetylacetonate to the reaction system and add 3 mL of tri-n-octylphosphine. React at 180 °C for 30 min, then stop introducing N2 and raise the temperature to 280 °C under sealed conditions for 2 h.

[0110] After the reaction, 15 mL of n-hexane and 30 mL of anhydrous ethanol were added to the solution containing the heterogeneous structured nanoparticles, ultrasonically shaken for 30 minutes, and then centrifuged at a speed of 10,000 rpm / min. Finally, the heterogeneous structured nanoparticles obtained by centrifugation were redispersed in n-hexane solution for storage.

[0111] The structure of the obtained heterostructured nanoparticles is as follows Figure 4 It can be seen that when the molar ratio of the first precursor of Pt and Ni is 1 / 3, the generated nanoparticles are not heterogeneous structures, but a single composition Pt-Ni-P alloy.

[0112] Comparative Example 2

[0113] This comparative example relates to the preparation of Pt-Ni-P alloy nanoparticles.

[0114] 39.3 mg of platinum acetylacetonate (Pt(acac)2) and 25.7 mg of nickel acetylacetonate (Ni(acac)2) were weighed and placed in a three-necked flask. 12 mL of octadecene and 5 mL of oleylamine were then added. Under high-purity nitrogen gas and magnetic stirring at 1000 rpm, cooling water was passed through the solution for reflux. The solution was first heated to 100°C and held for 30 minutes to remove impurities and moisture from the solution while dissolving the platinum and nickel precursors into the organic solution. The temperature was then raised to 180°C for 2 hours. 2 mL of tri-n-octylphosphine was then added, and the temperature was raised to 280°C for 2 hours. After the reaction, 15 mL of n-hexane and 30 mL of anhydrous ethanol were added to the heterogeneous nanoparticle solution. The solution was ultrasonically shaken for 30 minutes and then centrifuged at 10,000 rpm / min. The resulting Pt-Ni-P alloy nanoparticles were redispersed in n-hexane for storage.

[0115] The structure of the obtained nanoparticles is shown in Figure 5. It can be seen that the prepared Pt-Ni-P alloy nanoparticles have a multi-branched structure and a particle size of about 15 nm.

[0116] Comparative Example 3

[0117] This comparative example relates to the preparation of PtNi alloy nanoparticles.

[0118] 39.3 mg of platinum acetylacetonate (Pt(acac)2) and 25.7 mg of nickel acetylacetonate (Ni(acac)2) were weighed and placed in a three-necked flask, followed by the addition of 12 mL of octadecene and 5 mL of oleylamine. Under high-purity N2 gas and magnetic stirring at 1000 rpm, cooling water was passed through for condensation reflux. The temperature was first heated to 100°C and maintained for 30 minutes to remove impurities and moisture in the solution, while dissolving the platinum and nickel precursors into the organic solution. The temperature was then raised to 180°C for 2 hours.

[0119] The structure of the obtained nanoparticles is shown in Figure 6. It can be seen that the prepared PtNi alloy nanoparticles have a multi-branched structure and a particle size of about 18.5 nm.

[0120] Comparative Example 4

[0121] This comparative example relates to the preparation of NiP (nickel phosphide) nanoparticles.

[0122] 25.7 mg of nickel acetylacetonate (Ni(acac)2) was weighed and placed in a three-necked flask, 12 mL of octadecene and 5 mL of oleylamine were added, and then 2.5 mL of tri-n-octylphosphine (TOP) was added. Under high-purity N2 gas and magnetic stirring at 1000 rpm, cooling water was passed through for condensation reflux. The temperature was first heated to 100°C and maintained for 30 minutes to remove impurities and moisture in the solution, while dissolving the platinum and nickel precursors into the organic solution. The temperature was then raised to 280°C and reacted for 2 hours.

[0123] The structure of the obtained nanoparticles is shown in Figure 7. It can be seen that the prepared NiP nanoparticles have a uniform spherical structure and a particle size of about 10 nm.

[0124] Comparative Example 5

[0125] A Pt-Ni-P alloy porous nanosphere catalyst was prepared with reference to patent document CN116404181A. A certain amount of cetyltrimethylammonium bromide powder was weighed and dissolved in water, followed by dissolving the chloroplatinic acid and nickel chloride in a molar ratio of 53:1 and 0.5:1, respectively. Ascorbic acid was then added to the mixture under air, and the mixture was reacted at 80°C for 6 hours to prepare a platinum-nickel alloy. The platinum-nickel alloy was then centrifuged, washed, and dispersed in ultrapure water. Sodium hypophosphite and sodium borohydride were then added and reacted at 25°C for 20 minutes. The molar ratios of the platinum-nickel alloy porous nanospheres to sodium hypophosphite were 1:2.25, and the molar ratios of sodium hypophosphite to sodium borohydride were 1:2. The mixture was then centrifuged, washed, and composited with Vulcan XC-72R conductive carbon black to obtain a PtNiP-NSs / C catalyst.

[0126] Test example

[0127] Catalysts containing the precious metal Pt are widely used in new energy, chemical, pharmaceutical, oil refining, and automobile exhaust purification, particularly in the new energy sector as catalysts for fuel cells, zinc-air batteries, and water electrolysis. Therefore, this application uses the heterostructured nanoparticles obtained in Example 1 as electrocatalysts for performance testing. It should be noted that the heterostructured nanoparticles described in this application were only tested for performance in a limited range of applications, but are equally applicable to other fields.

[0128] 1. Oxygen evolution reaction (OER) test

[0129] Electrochemical performance tests were conducted on an electrochemical workstation using a standard three-electrode system. The prepared PtNi / NiP, Pt-Ni-P, PtNi, and NiP slurries were dropped onto a glassy carbon electrode as the working electrode, a platinum sheet as the counter electrode, and an Ag / AgCl reference electrode. The electrolyte was 1.0 M KOH, and the voltage range was set to 0-1.7 V at a scan rate of 5 mV / s. The measurement results are shown in Figure 2. Figure 8 shown.

[0130] Generally, the smaller the overpotential of the oxygen evolution reaction, the faster the reaction and the higher the catalytic performance. Figure 8 It can be seen that PtNi / NiP heterostructure nanoparticles have a high -2 The overpotential at 296 mV is lower than that of the homemade Pt-Ni-P (320 mV) of Comparative Example 2, the PtNi (330 mV) of Comparative Example 3, the NiP (390 mV) of Comparative Example 4, the PtNiP-NSs / C (316 mV) of Comparative Example 5, and the commercial IrO2 (345 mV) catalyst. The Pt-Ni-P nanoparticles of Comparative Example 1 and the Pt-Ni-P nanoparticles of Comparative Example 2 have similar overpotentials, which are not shown in the figure. This shows that the PtNi / NiP heterogeneous nanoparticles have excellent oxygen evolution activity and can be used as a potential anode catalyst for water electrolysis.

[0131] 2Methanol fuel cell test

[0132] PtNi / NiP heterostructured nanoparticles and commercial Pt / C are used as anode catalysts for fuel cells, and Pt / C is used as cathode catalyst. First, an anode catalyst, a proton exchange membrane, a cathode catalyst, and a gas diffusion layer are required to make a membrane electrode. The method is as follows: one of the catalysts is mixed into a uniform slurry, then added to an ultrasonic sprayer, carbon paper is used as a gas transfer layer, and then the catalyst is evenly sprayed onto the carbon paper. The sprayed carbon paper and proton exchange membrane are then hot-pressed to form a membrane electrode. Finally, the membrane electrode and bipolar plate are combined into a fuel cell device, and the methanol fuel cell performance test is performed on an electrochemical workstation. The measurement results are as follows: Figure 9 shown.

[0133] from Figure 9 It can be seen that when PtNi / NiP heterostructured nanoparticles are used as anode catalysts for methanol fuel cells, the maximum power density of the methanol fuel cell is 31mW / cm 2 , higher than commercial Pt / C (28.6mW / cm 2 ), indicating that PtNi / NiP heterostructured nanoparticles can be used as excellent methanol fuel cell catalysts.

Claims

1. A method for preparing heterostructured nanoparticles, wherein the heterostructured nanoparticles comprise a first phase and a second phase in contact with each other, the first phase being an alloy comprising platinum, nickel, and optionally phosphorus, and the second phase comprising nickel phosphide, the method comprising the following steps: reacting a platinum precursor and a first nickel precursor in the presence of a reducing agent to obtain alloy nanoparticles containing platinum and nickel elements; A second nickel precursor and a phosphorus source are added to the alloy nanoparticles to react and the reaction product is separated to obtain heterogeneous structure nanoparticles.

2. The preparation method according to claim 1, wherein the molar ratio of the platinum element in the platinum precursor to the nickel element in the first nickel precursor is 1:2-10:

1.

3. The preparation method according to claim 1, wherein reacting the platinum precursor and the first nickel precursor in the presence of a reducing agent comprises the following steps: reacting a platinum precursor and a first nickel precursor in the presence of a reducing agent at a temperature of 50-200° C. for 0.5-3 h; The temperature is then raised to 100-300° C. and the reaction is carried out for 0.5-5 hours to obtain alloy nanoparticles containing platinum and nickel elements.

4. The preparation method according to any one of claims 1 to 3, wherein the molar ratio of the platinum element in the platinum precursor to the nickel element in the second nickel precursor is 1:5-1:

1. 5 . The preparation method according to claim 1 , wherein the molar ratio of the second nickel precursor to the phosphorus source is 1:5-1:

40.

6. The preparation method according to any one of claims 1 to 3, wherein the platinum precursor is selected from one or more of a platinum complex, chloroplatinic acid, chloroplatinates, and organic acid salts of platinum.

7. The preparation method according to any one of claims 1 to 3, wherein the first nickel precursor and the second nickel precursor are independently selected from one or more of nickel complexes, nickel organic acid salts, and nickel inorganic acid salts.

8. The preparation method according to any one of claims 1 to 3, wherein the reducing agent is an organic amine.

9. The preparation method according to any one of claims 1 to 3, wherein the phosphorus source is organic phosphorus.

10. The preparation method according to any one of claims 1 to 3, wherein the first phase comprises spherical or hemispherical nanospheres, and the second phase comprises nanorods.

11. A heterostructured nanoparticle comprising a first phase and a second phase in contact with each other, wherein the first phase is an alloy comprising platinum, nickel, and optionally phosphorus, and the second phase comprises nickel phosphide.

12. The nanoparticle according to claim 11, wherein the first phase comprises spherical or hemispherical nanospheres and the second phase comprises nanorods. The nanoparticle according to claim 12 , wherein the average diameter of the nanospheres is 6-18 nm. The nanoparticle according to claim 12 , wherein the nanorods have an average length of 10-40 nm and an average width of 4-7 nm.

15. The nanoparticle according to any one of claims 11 to 14, wherein the nanoparticle is prepared by the preparation method according to any one of claims 1 to 10.

16. Use of the nanoparticles according to any one of claims 11 to 15 as a catalyst in a catalytic reaction.

17. Use of the nanoparticles according to any one of claims 11 to 15 as a catalyst in a fuel cell, a zinc-air battery or water electrolysis.

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