Preparation method of hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst

Abstract

The invention relates to the technical field of intermetallic compound catalysts, and particularly discloses a preparation method of a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst, which comprises the following steps: weighing octadecene and oleylamine, and mixing to obtain a solution A; platinum acetylacetonate, bismuth acetate, ascorbic acid and hexadecyl trimethyl ammonium bromide are weighed and sequentially poured into the solution A, and a solution B is obtained through mixing and ultrasonic treatment; heating and preserving heat of the solution B, and naturally cooling to room temperature to obtain a turbid liquid C; and measuring cyclohexane and ethanol, sequentially pouring into the turbid liquid C, carrying out ultrasonic treatment at room temperature for 3 minutes, then pouring out supernate, repeating for 2-3 times, collecting a product, and drying to obtain the nanocrystalline catalyst. According to the invention, the electron interaction between bimetallic components is utilized, the electron structure of a catalytic active center is optimized, the interaction between the active structure and reaction active species is enhanced, the evolution kinetics of a plurality of reaction intermediates such as * O and * OOH in the electrocatalytic oxygen reduction reaction can be obviously accelerated, and the kinetics rate of the four-electron oxygen reduction reaction is improved.

Description

Technical Field

[0001] The invention relates to the technical field of intermetallic compound catalysts, in particular to a method for preparing a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst. Background Art

[0002] To meet the needs of social development, the development of efficient and clean new energy conversion and storage technologies is urgent. New-generation energy conversion technologies, such as fuel cells, are currently attracting significant attention in the energy sector due to their high efficiency, cleanliness, and reliability. However, they are still limited by slow kinetics, necessitating the development of efficient catalyst materials. Pt-based catalysts play a crucial role in typical energy catalytic reactions, such as oxygen reduction. The development of efficient, stable, and low-cost Pt-based catalysts has been a research hotspot in the field of nanomaterials for nearly two decades.

[0003] Key development strategies for Pt-based catalysts include alloying Pt with other metals to manipulate electronic structure, constructing Pt nanocrystals of varying shapes to optimize atomic arrangement, and surface-modifying metal oxides to optimize electrochemical reactions. Among these, Pt-based intermetallic compounds (IMCs) are formed by ordering the atomic positions of their constituent elements. These compounds, characterized by long-range ordered atomic arrangements, isolated active sites, and abundant heteroatomic bonds, typically exhibit excellent catalytic activity, selectivity, and stability, and are currently at the forefront of electrocatalyst research. However, the high kinetic energy barrier of this atomic ordering process often requires high temperatures, limiting the controllable structure and function of these compounds. The systematic preparation of Pt-based IMCs using low-temperature liquid-phase methods is particularly challenging. Although IMCs have been extensively studied as electrocatalysts for various reactions relevant to fuel cell devices over the past decade, research on the controllable preparation of Pt-based IMCs remains limited. Current research focuses on further upgrading IMCs by maximizing electrocatalytic surface area, optimizing surface physics and chemistry, and optimizing operational stability. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst to solve the problems in the prior art.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for preparing a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst. The raw materials required for preparing the nanocrystalline catalyst are as follows: 2-10 mL of octadecene, 2-10 mL of oleylamine, 10-30 mg of platinum acetylacetonate, 10-30 mg of bismuth acetate, 70-90 mg of ascorbic acid, 300-400 mg of hexadecyltrimethylammonium bromide, 2-10 mL of cyclohexane, and 0.5-2 mL of ethanol.

[0007] Furthermore, the preparation process comprises the following steps:

[0008] S1. Measure octadecene and oleylamine, pour into a 50 mL beaker, mix, and mechanically stir at room temperature to obtain a uniformly dispersed solution A;

[0009] S2. Weigh platinum acetylacetonate, bismuth acetate, ascorbic acid, and cetyltrimethylammonium bromide, and pour them into solution A in sequence. Mix and ultrasonicate at room temperature for 5 minutes to obtain solution B.

[0010] S3. Pour solution B into a glass bottle with a lid, then place it in a metal heating module, set a heating program to increase the temperature, then heat and keep warm, and then naturally cool to room temperature to obtain suspension C;

[0011] S4. Measure cyclohexane and ethanol, pour them into suspension C in sequence, ultrasonicate at room temperature for 3 minutes, then centrifuge and discard the supernatant, repeat this step 2-3 times, collect the product, and dry it to obtain a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst.

[0012] Furthermore, the mechanical stirring time in S2 is 5-10 minutes, and the mechanical stirring time in S3 is 10-15 minutes.

[0013] Furthermore, the bismuth salt may be bismuth acetate or bismuth nitrate.

[0014] Furthermore, in S3, the heating time is controlled to be 15-20 minutes, and the heating temperature is raised to 200-210°C.

[0015] Furthermore, the holding time in S3 is 6-8 hours.

[0016] Furthermore, the centrifugation in S4 is performed at a speed of 8000-9000 rpm for 5-6 minutes.

[0017] Furthermore, the drying process in S4 is: drying in a vacuum drying oven at 60° C. for 6 hours.

[0018] Beneficial effects of the present invention:

[0019] 1. The present invention provides a method for preparing a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst. The method constructs a Pt-Bi intermetallic compound ultra-thin nanosheet catalyst material through a low-temperature liquid phase method. The formed Pt-based intermetallic compound nanosheet structure can increase the electrochemical active area, ensure that the reaction medium can fully contact the active sites, effectively promote electron and mass transfer in the electrocatalytic process, and thus improve the kinetic activity of the electrocatalytic reaction.

[0020] 2. The present invention provides a method for preparing a hexagonal layered Pt-Bi intermetallic compound nanocrystal catalyst. This method is not only simple and easy to operate, but also utilizes electronic interactions between the bimetallic components to effectively optimize the electronic structure of the catalytic active center and strengthen the interaction between the active structure and reactive species. In particular, in applications involving electrocatalytic oxygen reduction reactions, this method can significantly accelerate the evolution of multiple reaction intermediates, such as *O and *OOH, and improve the kinetic rate of the four-electron oxygen reduction reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below with reference to the accompanying drawings.

[0022] Figure 1 This is a transmission electron microscope (TEM) image of hexagonal layered PtBi intermetallic compound nanocrystals;

[0023] Figure 2 This is a high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image of hexagonal layered PtBi intermetallic compound nanocrystals;

[0024] Figure 3 yes Figure 2 A local magnified image in the scanning transmission electron microscope image;

[0025] Figure 4 is the X-ray diffraction (XRD) pattern of hexagonal layered PtBi intermetallic compound nanocrystals;

[0026] Figure 5 This is a performance diagram of hexagonal layered PtBi intermetallic compound nanocrystals electrocatalyzing oxygen reduction reaction. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] A method for preparing a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst. The raw material ratio required for preparing the hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst is as follows: 2-10 mL of octadecene, 2-10 mL of oleylamine, 10-30 mg of platinum acetylacetonate, 10-30 mg of bismuth acetate, 70-90 mg of ascorbic acid, 300-400 mg of hexadecyltrimethylammonium bromide, 2-10 mL of cyclohexane, and 0.5-2 mL of ethanol.

[0029] The preparation process includes the following steps:

[0030] S1. Measure octadecene and oleylamine, pour into a 50 mL beaker, mix, and mechanically stir at room temperature for 5-10 minutes to obtain a uniformly dispersed solution A.

[0031] S2. Weigh platinum acetylacetonate, bismuth acetate, ascorbic acid, and cetyltrimethylammonium bromide, and pour them into solution A in sequence. Mix by ultrasonication at room temperature for 5 minutes, and then mechanically stir for 10-15 minutes to obtain solution B.

[0032] In this embodiment, the bismuth salt can be bismuth acetate or bismuth nitrate.

[0033] S3. Pour solution B into a covered glass bottle, then place it in a metal heating block. Set the heating program to control the temperature to rise to 200-210°C over 15-20 minutes, then heat and keep it at 200-210°C for 6-8 hours, and then naturally cool it to room temperature to obtain suspension C.

[0034] The metal heating module is an existing technology, and the model used is Shanghai Yetuo YT-20.

[0035] S4. Measure cyclohexane and ethanol and pour them sequentially into suspension C. Ultrasonicate at room temperature for 3 minutes, then centrifuge at 8000-9000 rpm for 5-6 minutes, and discard the supernatant. Repeat this step twice, i.e., centrifuge 2-3 times using a mixed solvent of cyclohexane and ethanol. Collect the product and dry it in a vacuum drying oven at 60°C for 6 hours to obtain a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst.

[0036] Example 1

[0037] A method for preparing a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst comprises the following steps:

[0038] S1. Measure 2 mL of octadecene and 2 mL of oleylamine, pour them into a 50 mL beaker, mix, and mechanically stir at room temperature for 5 min to obtain a uniformly dispersed solution A.

[0039] S2. Weigh 10 mg of platinum acetylacetonate, 10 mg of bismuth acetate, 70 mg of ascorbic acid, and 300 mg of cetyltrimethylammonium bromide, and pour them into solution A in sequence. Mix by ultrasonication at room temperature for 5 min, and then mechanically stir for 10 min to obtain solution B.

[0040] S3. Pour solution B into a covered glass bottle, then place it in a metal heating block. Set a heating program to control the temperature to rise to 200°C over 15 minutes, then heat and hold at 200°C for 7 hours, and then naturally cool to room temperature to obtain suspension C.

[0041] S4. Measure 2 mL of cyclohexane and 0.5 mL of ethanol and pour them sequentially into suspension C. Ultrasonicate at room temperature for 3 minutes, then centrifuge at 8000 rpm for 5 minutes, and discard the supernatant. Repeat this step twice, using a mixed solvent of cyclohexane and ethanol for centrifugation twice. Collect the product and dry it in a vacuum drying oven at 60°C for 6 hours to obtain a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst.

[0042] Example 2

[0043] A method for preparing a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst comprises the following steps:

[0044] S1. Measure 5 mL of octadecene and 5 mL of oleylamine, pour them into a 50 mL beaker, mix, and mechanically stir at room temperature for 10 min to obtain a uniformly dispersed solution A.

[0045] S2. Weigh 20 mg of platinum acetylacetonate, 20 mg of bismuth acetate, 80 mg of ascorbic acid, and 350 mg of cetyltrimethylammonium bromide, and pour them into solution A in sequence. Mix by ultrasonication at room temperature for 5 min, and then mechanically stir for 15 min to obtain solution B.

[0046] S3. Pour solution B into a glass bottle with a lid, then place it in a metal heating block. Set a heating program to control the temperature to rise to 210°C in 20 minutes, then heat and hold at 210°C for 6 hours, and then naturally cool to room temperature to obtain suspension C.

[0047] S4. Measure 5 mL of cyclohexane and 1 mL of ethanol and pour them sequentially into suspension C. Ultrasonicate at room temperature for 3 minutes, then centrifuge at 8000 rpm for 6 minutes, and discard the supernatant. Repeat this step twice, i.e., centrifuge three times using a mixed solvent of cyclohexane and ethanol. Collect the product and dry it in a vacuum drying oven at 60°C for 6 hours to obtain a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst.

[0048] Example 3

[0049] A method for preparing a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst comprises the following steps:

[0050] S1. Measure 10 mL of octadecene and 10 mL of oleylamine, pour them into a 50 mL beaker, mix, and mechanically stir at room temperature for 10 min to obtain a uniformly dispersed solution A.

[0051] S2. Weigh 30 mg of platinum acetylacetonate, 30 mg of bismuth acetate, 90 mg of ascorbic acid, and 400 mg of cetyltrimethylammonium bromide, and pour them into solution A in sequence. Mix by ultrasonication at room temperature for 5 min, and then mechanically stir for 15 min to obtain solution B.

[0052] S3. Pour solution B into a glass bottle with a lid, then place it in a metal heating block. Set a heating program to control the temperature to rise to 210°C in 20 minutes, then heat and hold at 210°C for 8 hours, and then naturally cool to room temperature to obtain suspension C.

[0053] S4. Measure 10 mL of cyclohexane and 2 mL of ethanol and pour them sequentially into suspension C. Ultrasonicate at room temperature for 3 minutes, then centrifuge at 9000 rpm for 6 minutes, and discard the supernatant. Repeat this step twice, i.e., centrifuge three times using a mixed solvent of cyclohexane and ethanol. Collect the product and dry it in a vacuum drying oven at 60°C for 6 hours to obtain a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst.

[0054] See also Figure 1-3 The morphology of PtBi intermetallic compound nanocrystals was characterized and their electrocatalytic oxygen reduction performance was tested. The relevant data are as follows:

[0055] Figure 1 This is a TEM image of a hexagonal layered PtBi intermetallic compound nanocrystalline catalyst material prepared by a simple low-temperature liquid phase method, showing a uniform hexagonal lamellar morphology.

[0056] Figure 2 This is the HAADF-STEM image of the hexagonal layered PtBi intermetallic compound nanocrystal catalyst. Figure 3 This is a partial enlarged HAADF-STEM image of the hexagonal layered PtBi intermetallic compound nanocrystal catalyst, reflecting the regular arrangement of Pt and Bi atoms.

[0057] Figure 4 This is an XRD pattern characterizing the crystal structure of hexagonal layered PtBi intermetallic compound nanocrystalline catalyst.

[0058] Figure 5 This is the electrochemical performance diagram of hexagonal layered PtBi intermetallic compound nanocrystals. The four-electron oxygen reduction performance of the sample was tested using a rotating disk electrode, and a high half-wave potential of more than 0.90Vvs.RHE was obtained, indicating that its reaction energy barrier was reduced.

[0059] Compared with the related art, the preparation method of the hexagonal layered PtBi intermetallic compound nanocrystalline catalyst provided by the present invention has the following beneficial effects:

[0060] 1. A Pt-based intermetallic compound catalyst material with a hexagonal lamellar morphology was constructed through a low-temperature liquid-phase method. The formed nanosheet structure can increase the electrochemical active area and effectively enhance the contact between the electrolyte and the active sites. Moreover, its unique regular atomic distribution can effectively optimize the electronic structure of the active metal Pt, ensuring the interaction efficiency between the reaction intermediate species and the catalytically active metal, thereby improving the kinetic activity of the electrocatalytic reaction.

[0061] Second, the proposed preparation process is simple, easy to operate, and readily scalable. By using surfactants and controlling the reaction heating time and temperature, a Pt-based intermetallic compound with a regularly arranged atomic structure is formed. The enhanced d-orbital overlap between atoms effectively stimulates the catalytic activity of the active metal Pt. Furthermore, the resulting intermetallic compound exhibits a hexagonal lamellar morphology, which facilitates rapid electron and mass transport during the reaction.

[0062] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A method for preparing a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst, characterized in that: The raw material ratio required for preparing the nanocrystalline catalyst is as follows: 2-10 mL of octadecene, 2-10 mL of oleylamine, 10-30 mg of platinum acetylacetonate, 10-30 mg of bismuth acetate, 70-90 mg of ascorbic acid, 300-400 mg of hexadecyltrimethylammonium bromide, 2-10 ml of cyclohexane, and 0.5-2 ml of ethanol.

2. The method for preparing a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst according to claim 1, characterized in that: The preparation process comprises the following steps: S1. Measure octadecene and oleylamine, pour into a 50 mL beaker, mix, and mechanically stir at room temperature to obtain a uniformly dispersed solution A; S2. Weigh platinum acetylacetonate, bismuth acetate, ascorbic acid, and cetyltrimethylammonium bromide, and pour them into solution A in sequence. Mix and ultrasonicate at room temperature for 5 minutes to obtain solution B. S3. Pour solution B into a glass bottle with a lid, then place it in a metal heating module, set a heating program to increase the temperature, then heat and keep warm, and then naturally cool to room temperature to obtain suspension C; S4. Measure cyclohexane and ethanol, pour them into suspension C in sequence, ultrasonicate at room temperature for 3 minutes, then centrifuge and discard the supernatant, repeat this step 2-3 times, collect the product, and dry it to obtain a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst.

3. The method for preparing a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst according to claim 2, characterized in that: The mechanical stirring time in S2 is 5-10 minutes, and the mechanical stirring time in S3 is 10-15 minutes.

4. The method for preparing a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst according to claim 3, characterized in that: The bismuth salt can be bismuth acetate or bismuth nitrate.

5. The method for preparing a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst according to claim 2, characterized in that: In S3, the heating time is controlled to be 15-20 minutes, and the heating temperature is raised to 200-210°C.

6. The method for preparing a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst according to claim 2, characterized in that: The holding time in S3 is 6-8h.

7. The method for preparing a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst according to claim 2, characterized in that: The S4 centrifuge is performed at a speed of 8000-9000 rpm for 5-6 minutes.

8. The method for preparing a hexagonal layered Pt-Bi intermetallic compound nanocrystalline catalyst according to claim 7, characterized in that: The drying process in S4 is: drying in a vacuum drying oven at 60° C. for 6 hours.

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