Mesoporous intermetallic compound pt3sn nanocrystal and preparation method and application thereof

Abstract

The application relates to the technical field of electrocatalysis, in particular to a mesoporous intermetallic compound Pt3Sn nanocrystal and a preparation method and application thereof, the preparation method is as follows: S1, dissolving potassium chloroplatinite and KIT-6 in deionized water and vacuum drying; S2, adding ascorbic acid, carrying out sealed reduction at room temperature, washing after reaction, and vacuum drying; S3, adding the product in the previous step and stannous chloride into an organic solvent, centrifuging after fully mixing, and vacuum drying; S4, calcining; S5, carrying out joule heat treatment under the protection of inert gas; S6, cleaning to remove KIT-6, washing, and vacuum drying; the mesoporous intermetallic compound Pt3Sn nanocrystal has a long-range ordered Ia3d cubic mesoporous structure, the particle size is 90-130 nm, and the whole presents a grid-shaped structure which is regularly arranged in the horizontal and vertical directions and interpenetrates and forms continuous and interconnected pore channels; the mesoporous intermetallic compound Pt3Sn nanocrystal is small in particle size, uniform in dispersion, not prone to agglomeration, good in stability and electrocatalytic activity.

Description

Technical Field

[0001] This invention relates to the field of electrocatalysis technology, and in particular to a mesoporous intermetallic compound Pt3Sn nanocrystal, its preparation method, and its application. Background Technology

[0002] Platinum-based nanomaterials are the most mature electrocatalysts, having been proven in several key reactions in industrial energy conversion devices and widely considered the benchmark catalyst for the HER reaction. However, scarce reserves and high prices have been obstacles to the large-scale use of platinum in practical applications. Alloying platinum with relatively inexpensive transition metals is a simple and effective strategy that can reduce the cost of catalyst materials while improving catalytic performance through ligand and strain effects.

[0003] Intermetallic compounds (IMCs) hold great promise for applications in catalysis due to their unique physical and chemical properties. Among them, platinum-based IMCs, with their well-defined atomic arrangement and strong d-orbital hybridization, exhibit enhanced electronic coupling and structural stability, making them one of the most promising alloy electrocatalysts for alkaline HER reactions. However, while miniaturizing catalysts to the nanoscale or even single-unit scale improves utilization and catalytic activity, it often comes at the cost of durability in order to develop catalysts with higher atom utilization and durability. Mesoporous IMCs with inherent mesoporous characteristics have emerged as promising candidates for overcoming this trade-off.

[0004] Mesoporous IMCs consist of an ordered nanocrystalline framework embedded in mesopores, forming uniform and robust nanoparticles. The high specific surface area and ordered pore network allow for excellent utilization of the nanoscale IMCs, increasing the exposure of their active sites and the adsorption efficiency of reactants. Furthermore, the mesoporous structure effectively inhibits the migration and aggregation of nanocrystals, thereby improving their durability under harsh conditions. The confined mesoporous structure can also act as a nanoreactor, creating a favorable local environment that accelerates mass and electron transport at the catalyst-electrolyte interface.

[0005] Introducing mesoporous structures into the IMC system not only endows the material with a high specific surface area, fully exposing the active crystal faces and active sites of the IMC, but also constructs continuous mass transfer channels, accelerating the diffusion and transport of electrolytes, reactants, and products, reducing mass transfer resistance in catalytic reactions, and improving catalytic kinetic efficiency. For example, Chinese invention patent application CN116532640A discloses an ultra-small intermetallic compound confined within mesoporous carbon interstices and its preparation method. Using mesoporous silica SBA-15 as a hard template, sulfur-containing amino acids are filled into the SBA-15 channels via capillary action as a carbon source. Simultaneously, potassium chloroplatinate and a transition metal source are also filled into the SBA-15 channels along with the sulfur-containing amino acids. The mass ratio of potassium chloroplatinate, SBA-15, and sulfur-containing amino acids is 1:5–10:20–30, and the metal mass is consistent with the atomic ratio in the formed Pt-based intermetallic compound. The reaction process also includes solvents and water. This invention investigates the catalytic activity and stability of PtFe ultrafine nanoparticles embedded in a mesoporous carbon support using electrocatalytic hydrogen evolution as a model reaction. The electrocatalytic results demonstrate excellent activity and stability, meeting the requirements of relevant applications and development. However, existing techniques for synthesizing mesoporous intermetallic compound Pt3Sn nanocrystals result in products with severe aggregation, poor stability, and low electrocatalytic activity. Summary of the Invention

[0006] To address the shortcomings of the existing technologies, this invention proposes a mesoporous intermetallic compound Pt3Sn nanocrystal, its preparation method, and its application, in order to solve the problems of severe product aggregation, poor stability, and poor electrocatalytic activity in the existing technologies.

[0007] The technical solution of this invention is implemented as follows: Firstly, this invention proposes a method for preparing mesoporous intermetallic compound Pt3Sn nanocrystals, comprising the following steps: S1. Dissolve potassium chloroplatinate and KIT-6 in deionized water, and then vacuum dry (preferably at a drying temperature of 50-60℃ and a drying time of 0.5-1h) to obtain a homogeneous mixture of potassium chloroplatinate and KIT-6. S2. Add ascorbic acid to the product from the previous step, and perform sealed reduction at room temperature. After the reaction is complete, wash and vacuum dry (preferably at a drying temperature of 50-60℃ and a drying time of 0.5-1h) to obtain the meso-Pt / KIT-6 intermediate. S3. Add the product from the previous step and stannous chloride to an organic solvent (such as ethanol), mix them evenly by ultrasonication, centrifuge, and vacuum dry (preferably at a drying temperature of 50-60℃ and a drying time of 0.5-1h) to obtain a homogeneous mixture of stannous chloride and meso-Pt / KIT-6 intermediate. S4. The product from the previous step is calcined under an NH3 atmosphere to obtain meso-a-PtSn / Pt3Sn / KIT-6. S5. Under inert gas protection, the product from the previous step is subjected to Joule heat treatment at a temperature of 500-550℃ to obtain meso-Pt3Sn / KIT-6. S6. First, clean the product from the previous step to remove KIT-6, then wash and vacuum dry (preferably at a drying temperature of 50°C for 2-3 hours) to obtain the final product.

[0008] Compared with the prior art, this invention uses KIT-6 as a template and adds Joule heat treatment after conventional calcination: (1) Using KIT-6 with a three-dimensional porous structure as a template can accelerate ion diffusion, facilitate bubble desorption, confine intermetallic compounds to refine particles, enrich heterogeneous interfaces and enhance catalytic activity; (2) By using the Joule rapid high-temperature heating process, the PtSn / Pt3Sn phase is converted into a higher purity Pt3Sn phase, avoiding particle agglomeration caused by long-term isothermal sintering; the two work synergistically, and the resulting product has small particle size, uniform dispersion and complete interconnected mesopores, thus exhibiting high electrocatalytic activity and stability. In addition, the Joule rapid high-temperature processing technology also helps to simplify the operation and significantly reduce the heat treatment time.

[0009] The preparation method proposed in this invention is simple to operate, efficient in preparation, has good reproducibility and high yield, and is conducive to industrial promotion and application.

[0010] Furthermore, in step S5, during Joule heat treatment, the input current is 9-11A, and heating for 8 seconds and cooling for 6 seconds constitute one cycle, for a total of 30 cycles.

[0011] In this technical solution, by controlling the input current to 9-11A, the temperature of the sample (PtSn / Pt3Sn phase) can be instantly raised to 500-550℃, and highly crystalline mesoporous intermetallic compound - pure Pt3Sn can be generated in a short time, avoiding particle agglomeration caused by long-term isothermal sintering.

[0012] In this technical solution, each cycle involves heating for 8 seconds and cooling for 6 seconds, with 30 such cycles performed. This process serves three purposes: First, rapid heating generates a tremendous thermodynamic driving force, causing atoms to arrange themselves into a sequential structure, i.e., an intermetallic compound, in a short time. Second, it effectively prevents nanoparticles from agglomerating and growing at high temperatures, maintaining the material's large specific surface area and high activity. Third, it can suppress the formation of impurity phases and improve the purity of the target product.

[0013] Furthermore, in step S1, the amount of potassium chloroplatinate added is 50-60 mg, and the amount of KIT-6 added is 0.2-0.3 g. In order to promote the full mixing of potassium chloroplatinate and KIT-6, ultrasonic treatment is preferred. In step S2, the concentration of ascorbic acid is 1 mol / L, the amount added is 2-3 mL, and the sealed reduction reaction time is not less than 10 h, for example, 10-11 h.

[0014] Furthermore, in step S3, the amount of meso-Pt / KIT-6 intermediate added is 0.2-0.3g, and the amount of stannous chloride added is 250-350mg. The means of thorough mixing include, but are not limited to, ultrasound and stirring, with ultrasound being preferred.

[0015] Furthermore, in step S4, the homogeneous mixture of stannous chloride and meso-Pt / KIT-6 intermediate is first placed in a heating furnace, and then the heating furnace is heated to the calcination temperature by programmed heating (preferably heating rate of 5℃ / min). The calcination temperature is 500-600℃ and the calcination time is 3-5h. During the calcination process, NH3 is introduced and the flow rate of NH3 is controlled at 80sccm. After the calcination is completed, the sample is naturally cooled to room temperature.

[0016] Furthermore, in step S6, the product from step S5 is washed with a 2 mol / L sodium hydroxide solution to remove KIT-6, followed by washing with deionized water and ethanol in sequence.

[0017] Secondly, this invention proposes a mesoporous intermetallic compound Pt3Sn nanocrystal, prepared using KIT-6 as a template. It combines the advantages of mesoporous and intermetallic compound crystal structures. The mesoporous structure enhances the utilization efficiency of catalytic sites, contributing to improved mass and surface activity of the catalyst. The stable mesoporous framework structure inhibits Ostwald ripening, enhancing the stability of the catalytic reaction. The intermetallic nanomaterials possess ligand, strain, and geometric effects, which can alter the coordination properties of the material and precisely optimize the reaction energy barrier. Therefore, the obtained mesoporous intermetallic compound Pt3Sn nanocrystals can not only effectively improve the activity and stability of electrocatalytic hydrogen evolution but also construct continuous mass transfer channels, accelerating the diffusion and transport of electrolyte, reactants, and products, thereby improving catalytic kinetic efficiency.

[0018] Furthermore, the mesoporous intermetallic compound Pt3Sn nanocrystals are uniformly loaded on the three-dimensional template KIT-6. After KIT-6 is etched, they still retain the long-range ordered Ia3d cubic mesoporous structure with a particle size of 90-130nm. Overall, they present a grid-like structure with regular arrangement and interpenetration in the transverse and longitudinal directions. The grid-like structure is interconnected to form continuous and interconnected pore channels.

[0019] Thirdly, this invention proposes the application of mesoporous intermetallic compound Pt3Sn nanocrystals, which are mixed with carbon black and drop-coated onto a rotating disk electrode as a cathode catalyst. After drying, they are used as the working electrode, with a saturated silver / silver chloride electrode as the reference electrode, a carbon rod as the counter electrode, and a 1 mol / L potassium hydroxide solution as the electrolyte to carry out an electrocatalytic hydrogen evolution reaction.

[0020] Furthermore, its mass ratio to carbon black is 1:1, and the loading of the cathode catalyst on the rotating disk electrode is 0.05 mg / cm². 2 .

[0021] In this technical solution, the area of ​​the rotating disk electrode is 0.196 cm². 2 Before use, a viscous polishing solution was prepared by mixing alumina powder with a particle size of 0.05 μm with deionized water. This solution was then evenly applied to the surface of the deerskin to polish the working electrode. The electrocatalytic hydrogen evolution reaction was carried out at 25 °C, with a reaction potential of -0.7 to -0.8 V relative to the saturated silver / silver chloride electrode. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a flowchart illustrating the preparation process of the mesoporous intermetallic compound Pt3Sn nanocrystals proposed in this invention. Figure 2 TEM images and particle size distribution diagrams of the product obtained in Example 1 and the product obtained in Comparative Example 1 are shown below: (a) is a TEM image of the product obtained in Example 1, (b) is a particle size distribution diagram of the product obtained in Example 1, (c) is a TEM image of the product obtained in Comparative Example 1, and (d) is a particle size distribution diagram of the product obtained in Comparative Example 1. Figure 3 TEM and HAADF-STEM images of the product obtained in Example 1: (a) TEM image; (b) HAADF-STEM image; Figure 4 The XRD patterns of the product obtained in Example 1 and the product obtained in Comparative Example 1 are shown below. Figure 5 Linear sweep voltammetry (LSV) curves of the products obtained in Example 1, Comparative Example 1, and Comparative Example 3; Figure 6 The bar chart shows the mass activity of the products obtained in Example 1, Comparative Example 1, and Comparative Example 3. Figure 7 Linear sweep voltammetry (LSV) curves of the products obtained in Example 1, Comparative Example 1, and Comparative Example 3 before and after 5000 cyclic voltammetry (CV) cycles; Figure 8 Linear sweep voltammetry (LSV) curves of the products obtained in Example 1 and Comparative Example 2; Figure 9 Linear sweep voltammetry (LSV) curves of the products obtained in Example 1, Comparative Example 4, and Comparative Example 5. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The raw materials or apparatus used in the following embodiments and comparative examples are all existing raw materials or apparatus; the operations not described in detail in the following embodiments and comparative examples are all conventional operating methods in the art.

[0026] It should be noted that in the following electrocatalytic hydrogen evolution reaction tests, the current density (j) within the applied voltage range was recorded using linear sweep voltammetry (LSV) to characterize the electrochemical behavior within that voltage range. The LSV scan rate was 5 mV / s. A constant voltage method was used to record the current-time (It) curve at the applied potential to record the catalyst stability. The working electrode was rotated at 1600 rpm to obtain the HER polarization curve. The LSV curves were corrected using 90% ohmic iR compensation.

[0027] Example 1 according to Figure 1 The preparation process shown, combined with the following steps, prepares mesoporous intermetallic compound Pt3Sn nanocrystals: S1. Dissolve 0.2g of KIT-6 molecular sieve and 53.3mg of potassium chloroplatinate in 2.0mL of deionized water, sonicate for 2min, place in a vacuum oven, dry at 50℃ for 0.5h to remove solvent under vacuum, and obtain a homogeneous mixture of potassium chloroplatinate and KIT-6. S2. Add 2.0 mL of freshly prepared 1 mol / L ascorbic acid to the homogeneous mixture of potassium chloroplatinate and KIT-6. After sealing the reaction flask, react at room temperature for 10 h. After the reaction is completed, wash with 10 mL of deionized water 3 times and then with 10 mL of ethanol once. Then place it in a vacuum drying oven and dry at 50 °C for 2 h to obtain meso-Pt / KIT-6 intermediate. S3. Take 0.25g of meso-Pt / KIT-6 intermediate and 300mg of stannous chloride and place them in an ethanol solution. Stir for 10min, centrifuge to collect the product and transfer it to a vacuum drying oven to dry at 50℃ for 2h. S4. The product from the previous step was placed in a heating furnace and calcined under an NH3 atmosphere. The heating rate of the furnace was 5℃ / min, the calcination temperature was 500℃, and the time was 4h. NH3 was introduced during the process at a flow rate of 80sccm. After calcination, the product was cooled to room temperature to obtain meso-a-PtSn / Pt3Sn / KIT-6. S5. Take 50 mg of the product from the previous step, meso-a-PtSn / Pt3Sn / KIT-6, and wrap it with carbon cloth. Under an argon atmosphere, perform periodic carbon thermal shock treatment using a Joule heating device. The process parameters are set as follows: input current 10.5 A, heating for 8 s and cooling for 6 s as one cycle, for a total of 30 cycles, to obtain meso-PtSn3 / KIT-6 powder. S6. The obtained meso-PtSn3 / KIT-6 powder was dispersed in 10 mL of 2 mol / L sodium hydroxide solution, sonicated for 15 min, and then centrifuged to collect the product. This operation was repeated twice to remove KIT-6. Then, the product was washed three times with 25 mL of deionized water and once with 25 mL of ethanol. The final product was dried in a vacuum oven at 50 °C for 2 h to obtain mesoporous intermetallic compound Pt3Sn nanocrystals (abbreviated as: meso-Pt3Sn).

[0028] like Figure 4 As shown: the diffraction peaks of the obtained product match well with the standard diffraction peaks of the Pt3Sn phase, indicating that it is a Pt3Sn crystalline phase. Figure 2 As shown in (a) and (b), the obtained meso-Pt3Sn particles are uniformly distributed, with a particle size of approximately 90-130 nm and an average particle size of 105 nm. To further clarify the crystal phase characteristics and microstructure details of meso-Pt3Sn, TEM and HAADF-STEM were used for characterization analysis, such as... Figure 3 As shown in (a): After etching the mesoporous template, the meso-Pt3Sn particles are uniformly arranged in different orientations, and their internal mesoporous structure exhibits a periodic, ordered arrangement and interconnection, which is consistent with the anti-double helix of the initial KIT-6 template. The crystal structure remains consistent; such asFigure 3 As shown in (b), its mesoporous channels are clearly distinguishable, with uniform and regular size. According to statistics, its average size is about 5.2 nm, which shows that the meso-Pt3Sn porous framework has good uniformity and integrity at the nanoscale.

[0029] Electrocatalytic hydrogen evolution reaction was performed using a CHI660e electrochemical workstation. A three-electrode system was employed, with a rotating disk electrode as the working electrode. The disk electrode was obtained by mixing meso-Pt3Sn and carbon black at a 1:1 mass ratio and adding 0.05 mg / cm³ of the mixture. 2 The loading amount was drop-coated onto an area of ​​0.196 cm². 2 The sample was dried on a rotating disk electrode; a saturated silver / silver chloride electrode was used as the reference electrode, a carbon rod electrode as the counter electrode, and a 1 mol / L potassium hydroxide solution as the electrolyte; the test temperature was 25℃, and the reaction potential relative to the saturated silver / silver chloride electrode was -0.7 to -0.8 V. Figure 5 As shown: at a current density of 10 mA / cm² 2 At this time, the overpotential of meso-Pt3Sn is extremely low, only 9mV, indicating that its HER catalytic performance is good.

[0030] Example 2 according to Figure 1 The preparation process shown, combined with the following steps, prepares mesoporous intermetallic compound Pt3Sn nanocrystals: S1. Dissolve 0.25g KIT-6 molecular sieve and 50mg potassium chloroplatinate in 2.0mL deionized water, sonicate for 2min, place in a vacuum oven, dry at 50℃ for 0.5h to remove solvent under vacuum, and obtain a homogeneous mixture of potassium chloroplatinate and KIT-6. S2. Add 2.5 mL of freshly prepared 1 mol / L ascorbic acid to the homogeneous mixture of potassium chloroplatinate and KIT-6. After sealing the reaction flask, react at room temperature for 11 h. After the reaction is completed, wash with 10 mL of deionized water 3 times and then with 10 mL of ethanol once. Then place it in a vacuum drying oven and dry at 50 °C for 2 h to obtain meso-Pt / KIT-6 intermediate. S3. Take 0.3g of meso-Pt / KIT-6 intermediate and 250mg of stannous chloride and place them in an ethanol solution. Stir for 10min, centrifuge to collect the product and transfer it to a vacuum drying oven to dry at 50℃ for 2h. S4. The product from the previous step was placed in a heating furnace and calcined under an NH3 atmosphere. The heating rate of the furnace was 5℃ / min, the calcination temperature was 600℃, and the time was 3h. NH3 was introduced during the process at a flow rate of 80sccm. After calcination, the product was cooled to room temperature to obtain meso-a-PtSn / Pt3Sn / KIT-6. S5. Take 50 mg of the product from the previous step, meso-a-PtSn / Pt3Sn / KIT-6, and wrap it with carbon cloth. Under an argon atmosphere, perform periodic carbon thermal shock treatment using a Joule heating device. The process parameters are set as follows: input current 11A, heating for 8 seconds and cooling for 6 seconds as one cycle, for a total of 30 cycles, to obtain meso-PtSn3 / KIT-6 powder. S6. The obtained meso-PtSn3 / KIT-6 powder was dispersed in 10 mL of 2 mol / L sodium hydroxide solution, sonicated for 15 min, and then centrifuged to collect the product. This operation was repeated twice to remove KIT-6. Then, the product was washed three times with 25 mL of deionized water and once with 25 mL of ethanol. The final product was dried in a vacuum oven at 50 °C for 2 h to obtain mesoporous intermetallic compound Pt3Sn nanocrystals (abbreviated as: meso-Pt3Sn).

[0031] The working electrode was fabricated using the same procedure as in Example 1 and tested. Linear sweep voltammetry (LSV) curves showed that the obtained product was effective at a current density of 10 mA / cm². 2 The overpotential was 11mV, indicating that it has good HER catalytic performance.

[0032] Example 3 according to Figure 1 The preparation process shown, combined with the following steps, prepares mesoporous intermetallic compound Pt3Sn nanocrystals: S1. Dissolve 0.3g of KIT-6 molecular sieve and 60mg of potassium chloroplatinate in 2.0mL of deionized water, sonicate for 2min, place in a vacuum oven, dry at 50℃ for 0.5h to remove solvent under vacuum, and obtain a homogeneous mixture of potassium chloroplatinate and KIT-6. S2. Add 3.0 mL of freshly prepared 1 mol / L ascorbic acid to the homogeneous mixture of potassium chloroplatinate and KIT-6. After sealing the reaction flask, react at room temperature for 12 h. After the reaction is completed, wash with 10 mL of deionized water 3 times and then with 10 mL of ethanol once. Then place it in a vacuum drying oven and dry at 50 °C for 2 h to obtain meso-Pt / KIT-6 intermediate. S3. Take 0.2g of meso-Pt / KIT-6 intermediate and 350mg of stannous chloride and place them in an ethanol solution. Stir for 10min, centrifuge to collect the product and transfer it to a vacuum drying oven to dry at 50℃ for 2h. S4. The product from the previous step was placed in a heating furnace and calcined under an NH3 atmosphere. The heating rate of the furnace was 5℃ / min, the calcination temperature was 550℃, and the time was 5h. During the calcination, NH3 was introduced at a flow rate of 80sccm. After calcination, the product was cooled to room temperature to obtain meso-a-PtSn / Pt3Sn / KIT-6. S5. Take 50 mg of the product from the previous step, meso-a-PtSn / Pt3Sn / KIT-6, and wrap it with carbon cloth. Under an argon atmosphere, perform periodic carbon thermal shock treatment using a Joule heating device. The process parameters are set as follows: input current 9A, heating for 8s and cooling for 6s as one cycle, for a total of 30 cycles, to obtain meso-PtSn3 / KIT-6 powder. S6. The obtained meso-PtSn3 / KIT-6 powder was dispersed in 10 mL of 2 mol / L sodium hydroxide solution, sonicated for 15 min, and then centrifuged to collect the product. This operation was repeated twice to remove KIT-6. Then, the product was washed three times with 25 mL of deionized water and once with 25 mL of ethanol. The final product was dried in a vacuum oven at 50 °C for 2 h to obtain mesoporous intermetallic compound Pt3Sn nanocrystals (abbreviated as: meso-Pt3Sn).

[0033] The working electrode was fabricated using the same procedure as in Example 1 and tested. Linear sweep voltammetry (LSV) curves showed that the obtained product was effective at a current density of 10 mA / cm². 2 The overpotential was 10mV, indicating that it has good HER catalytic performance.

[0034] Comparative Example 1 Compared to Example 1, step S5 was omitted, while all other steps remained the same as in Example 1. Meso-PtSn / Pt3Sn nanoparticles were obtained.

[0035] like Figure 4 As shown: The diffraction peaks of the obtained product simultaneously exhibit characteristic diffraction peaks of both Pt3Sn and PtSn intermetallic phases. Pt3Sn is a Cu3Au type ordered crystal phase, corresponding to space group Pm3m, while PtSn is a NiAs type hexagonal crystal phase, corresponding to space group P63 / mmc. Figure 2 As shown in (c) and (d): Without Joule heat treatment, the obtained product is meso-PtSn / Pt3Sn nanoparticles with an average particle size of 190 nm. The size uniformity is poor, and the particle size distribution range is wide, with a dispersion interval of approximately 120 nm. Figure 2A comparison of (a) and (b) shows that Joule heat treatment reduces the average particle size of the product from 190 nm to 105 nm, and significantly narrows the particle size distribution range, improving size uniformity. This indicates that Joule heat treatment resulted in significant phase purification of the sample, with the meso-PtSn / Pt3Sn mixed phase being oriented to transform into a pure Pt3Sn phase. Furthermore, during the rapid heating and cooling cycles, metal atoms exhibit high migration along the substrate surface, and the nanoparticles undergo efficient structural reorganization, ultimately leading to a reduction in material particle size and homogenization.

[0036] Furthermore, such as Figure 5 As shown: at a current density of 10 mA / cm² 2 At this time, the overpotential of the meso-PtSn / Pt3Sn nanoparticles was 43 mV, significantly higher than that of the meso-Pt3Sn in Example 1. This demonstrates that Joule heat treatment optimizes the structure and crystal phase of meso-Pt3Sn, playing a crucial role in enhancing the HER catalytic performance.

[0037] Comparative Example 2 The meso-Pt3Sn was prepared using SBA-15 as a template. The specific operation is as follows: Compared with Example 1, the template agent KIT-6 in step S1 was adjusted to an equal amount of SBA-15, and the rest remained the same as in Example 1.

[0038] like Figure 8 As shown: at a current density of 10 mA / cm² 2 At that time, the overpotential (9mV) of the product obtained in Example 1 was significantly lower than that of Comparative Example 2 (23mV), indicating that the electrocatalytic activity of meso-Pt3Sn prepared by the preparation method proposed in this invention is significantly better than that of meso-Pt3Sn prepared by the prior art shown in Comparative Example 2. It is evident that the mesoporous intermetallic compound Pt3Sn nanocrystals prepared using the three-dimensional template KIT-6 have far superior electrocatalytic performance compared to the product prepared using the two-dimensional template SBA-15.

[0039] Comparative Example 3 Compared with Example 1, only steps S1, S2, and S6 were performed to obtain meso-Pt; the rest remained the same as in Example 1.

[0040] like Figure 5 As shown: at a current density of 10 mA / cm² 2 At that time, the overpotential of meso-Pt was 31mV, which was significantly higher than that of meso-Pt3Sn in Example 1.

[0041] The catalytic activities of the products obtained in Example 1, Comparative Example 1, and Comparative Example 3 were compared, such as... Figure 6As shown, meso-Pt3Sn (Example 1) exhibited the best catalytic activity, with mass activity (MA) approximately 11 times, 5.8 times, and 4.6 times that of meso-PtSn / Pt3Sn (Comparative Example 1), meso-Pt (Comparative Example 3), and commercial Pt / C, respectively. Simultaneously, its specific activity (SA) was approximately 8.5 times, 2.8 times, and 2.7 times that of the aforementioned three samples, highlighting the advantages of meso-Pt3Sn in reducing Pt dosage and improving catalytic efficiency. Figure 7 As shown: After 5000 accelerated durability tests, the overpotential of meso-Pt3Sn increased by only 4 mV, while that of meso-PtSn / Pt3Sn and meso-Pt increased by 16 mV and 13 mV, respectively, indicating that meso-Pt3Sn exhibited the smallest catalytic activity decay during long-term cycling. Furthermore, electrochemical chronoamperometry (CP) measurements showed that meso-Pt3Sn exhibited the smallest overpotential decay at 10 mA / cm². 2 After working continuously for 25 hours under a constant current, it can still maintain overall stable operation without any sudden degradation of the current, indicating that meso-Pt3Sn has good working stability.

[0042] Comparative Example 4 Compared to Example 1, the input current in step S5 was adjusted to 7A, the temperature was raised to 270°C for 8 seconds and then cooled for 6 seconds; all other steps remained the same as in Example 1. The resulting product was a meso-PtSn / Pt3Sn mixed phase.

[0043] Comparative Example 5 Compared to Example 1, the input current in step S5 was adjusted to 13A, the temperature was raised to 850°C for 8 seconds and then cooled for 6 seconds; all other steps remained the same as in Example 1. The resulting product was a meso-PtSn / Pt3Sn mixed phase.

[0044] like Figure 9 As shown: at a current density of 10 mA / cm² 2 When the overpotential (9mV) of the product obtained in Example 1 was significantly lower than that of Comparative Example 4 (26mV) and Comparative Example 5 (23mV), it indicates that its electrocatalytic activity was significantly higher than that of Comparative Example 4 and Comparative Example 5. It can be seen that the magnitude of the input current during Joule heat treatment has a significant impact on the electrocatalytic activity of the product, and 9-11A is preferable. Too high or too low a current is not conducive to the electrocatalytic activity of the product.

[0045] In summary, this invention, using KIT-6 as a template and through the synergistic effect of Joule heat treatment, yielded pure Pt3Sn nanocrystals with small particle size, uniform dispersion, and intact interconnected mesopores, exhibiting good electrocatalytic activity and high operational stability. The preparation method proposed in this invention is simple to operate, highly efficient, reproducible, and yields high quantities, making it suitable for industrial application.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing mesoporous intermetallic compound Pt3Sn nanocrystals, characterized in that: The following steps are included: S1. Dissolve potassium chloroplatinate and KIT-6 in deionized water, and then dry under vacuum; S2. Add ascorbic acid to the product from the previous step, and perform sealed reduction at room temperature. After the reaction is complete, wash and vacuum dry. S3. Add the product from the previous step and stannous chloride to an organic solvent, mix thoroughly, centrifuge, and vacuum dry. S4. Calcine the product from the previous step under an NH3 atmosphere; S5. Under the protection of inert gas, the product from the previous step is subjected to Joule heat treatment at a temperature of 500-550℃. S6. First, clean the product from the previous step to remove KIT-6, then wash and vacuum dry to obtain the final product.

2. The method for preparing mesoporous intermetallic compound Pt3Sn nanocrystals according to claim 1, characterized in that: In step S5, during Joule heat treatment, the input current is 9-11A, and heating for 8 seconds and cooling for 6 seconds constitute one cycle, for a total of 30 cycles.

3. The method for preparing mesoporous intermetallic compound Pt3Sn nanocrystals according to claim 1, characterized in that: In step S1, the amount of potassium chloroplatinate added is 50-60 mg, and the amount of KIT-6 added is 0.2-0.3 g. After dissolution, it is subjected to ultrasonic treatment. In step S2, the concentration of ascorbic acid is 1 mol / L, the amount added is 2-3 mL, and the sealed reduction reaction time is not less than 10 h.

4. The method for preparing mesoporous intermetallic compound Pt3Sn nanocrystals according to claim 1, characterized in that: In step S3, the amount of meso-Pt / KIT-6 intermediate added is 0.2-0.3g, and the amount of stannous chloride added is 250-350mg. The means of thorough mixing include, but are not limited to, sonication and stirring.

5. The method for preparing mesoporous intermetallic compound Pt3Sn nanocrystals according to claim 1, characterized in that: In step S4, the homogeneous mixture of stannous chloride and meso-Pt / KIT-6 intermediate is first placed in a heating furnace, and then the heating furnace is heated to the calcination temperature by programmed temperature increase. The calcination temperature is 500-600℃ and the calcination time is 3-5h. During the calcination process, NH3 is introduced and the flow rate of NH3 is controlled at 80sccm. After the calcination is completed, the sample is naturally cooled to room temperature.

6. The method for preparing mesoporous intermetallic compound Pt3Sn nanocrystals according to claim 1, characterized in that: In step S6, the product from step S5 is washed with a 2 mol / L sodium hydroxide solution to remove KIT-6, followed by washing with deionized water and ethanol.

7. A mesoporous intermetallic compound Pt3Sn nanocrystal prepared according to the preparation method according to any one of claims 1-6.

8. The mesoporous intermetallic compound Pt3Sn nanocrystals according to claim 7, characterized in that: It has a long-range ordered Ia3d cubic mesoporous structure with a particle size of 90-130nm. Overall, it presents a grid-like structure with regular arrangement and interpenetration in the transverse and longitudinal directions. The grid-like structure is interconnected to form continuous and interconnected pore channels.

9. An application of the mesoporous intermetallic compound Pt3Sn nanocrystals as described in claim 7 or 8, characterized in that: It was mixed with carbon black and used as a cathode catalyst by drop coating onto a rotating disk electrode. After drying, it was used for the electrocatalytic hydrogen evolution reaction.

10. The application of the mesoporous intermetallic compound Pt3Sn nanocrystals according to claim 9, characterized in that: Its mass ratio with carbon black is 1:1, and the loading of the cathode catalyst on the rotating disk electrode is 0.05 mg / cm³. 2 .

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