Pt5Co catalyst and preparation method and application thereof

Abstract

The invention discloses a Pt5Co catalyst as well as a preparation method and application thereof, and belongs to the technical field of catalysts. According to the preparation method provided by the invention, H2PtCl6 and CoCl2 are adopted as raw materials to synthesize Pt5Co nano-particles, the Pt5Co nano-particles are loaded on a carbon carrier etched by CO2, and then Joule heating is performed to obtain the Pt5Co catalyst. The Pt5Co nanoparticles of the catalyst are uniform in size and good in dispersity, have highly ordered atomic arrangement, show excellent HER (hydrogen evolution reaction) performance in hydrogen evolution reaction, and have excellent application potential.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to a Pt5Co catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Pt-based catalysts are the most promising electrocatalysts for the hydrogen evolution reaction (HER) in industrial applications. Due to their moderate hydrogen adsorption energy, they can significantly reduce the overpotential. However, the development of highly efficient Pt-based catalysts with low Pt loading and high utilization efficiency remains challenging. In recent years, the design of Pt-based multi-component catalysts through alloying strategies has become a research hotspot. Among them, the PtCo alloy shows significant potential for performance improvement due to its synergistic effect and structural optimization. Alloying is an important means to improve the performance of Pt-based catalysts. In the PtCo system, the introduction of Co can optimize the electronic structure of Pt through electronic and geometric effects, reduce the hydrogen adsorption free energy (ΔGH*), and at the same time improve the corrosion resistance of the catalyst. PtCo catalysts show different performances under different pH conditions. In acidic media, the proton transfer rate is fast, and the electronic structure optimization of the PtCo alloy is more likely to achieve efficient HER. However, the structural regulation of the PtCo alloy is difficult. As the Pt loading increases, the particle size of the PtCo alloy is likely to increase, and the Co content will gradually decrease due to the displacement reaction, making it difficult to maintain the ideal alloy structure. Moreover, the existing preparation processes are complex, involving multiple steps of reactions (such as pyrolysis, displacement, heat treatment), and the conditions of each step (such as temperature, atmosphere, time) need to be strictly controlled. Summary of the Invention

[0003] Aiming at the above-mentioned prior art, the present invention provides a Pt5Co catalyst, a preparation method thereof, and an application thereof, which solve the problems of difficult alloy structure regulation, poor catalytic performance, and strict preparation conditions of the existing Pt-based catalysts as electrolytic water catalysts.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is: to provide a preparation method of a Pt5Co catalyst, comprising the following steps:

[0005] S1: Mix H2PtCl6 and CoCl2 in a molar ratio of Pt:Co = 5:1, and then dissolve them in ethanol to obtain a precursor solution;

[0006] S2: Keep the carbon black material in a CO2 atmosphere at 650 - 750 °C for 4 - 8 h to obtain a pretreated carbon black material; mix the pretreated carbon black material and melamine in a mass ratio of 4 - 6:1, and then keep it in an inert atmosphere at 650 - 750 °C for 1 h to obtain a carbon support;

[0007] S3: Add the carbon support to the precursor solution, mix evenly by ultrasonic treatment, let stand for 24 - 48 h, add deionized water after standing to conduct freezing, and obtain a frozen sample; then freeze-dry the frozen sample to obtain a crude product.

[0008] S4: Conduct Joule heating on the crude product to obtain the Pt5Co catalyst.

[0009] Based on the above technical solutions, the present invention can also be improved as follows.

[0010] Further, the Pt source is H2PtCl6, and the Co source is CoCl2 or Co(NO3)2·6H2O.

[0011] Further, the concentration of the precursor solution is 0.04 - 0.06 mol / L.

[0012] Further, the carbon black material is conductive carbon black.

[0013] Further, the material ratio of the carbon support to the precursor solution is 1 g:2 mL.

[0014] Further, the Joule heating is carried out at 1000 - 1200 °C for 50 mS.

[0015] The beneficial effects of the present invention are as follows: The present invention uses H2PtCl6 and CoCl2 as raw materials, which are supported on the conductive substrate of carbon nanofibers to ensure their uniform dispersion and efficient heat conduction. Then, through the method of rapid Joule heating, Pt and Co are synthesized into highly ordered and well-dispersed intermetallic nanoparticles in a short time, and finally the Pt5Co catalyst is obtained; this method heats up to 1000 - 1200 °C at an extremely high heating rate and then reacts in an extremely short time, greatly shortening the synthesis time and significantly improving the production efficiency. At the same time, the extremely short heating time effectively inhibits the sintering and agglomeration of nanoparticles, and the prepared Pt5Co nanoparticles have uniform size and good dispersion. The present invention realizes a 100% long-range order (LRO) structure by precisely controlling the heating temperature and time, making the formed Pt5Co nanoparticles have a highly ordered atomic arrangement; in summary, the preparation process provided by the present invention is simple, the prepared product has excellent performance, and has good industrial prospects.

[0016] The present invention also provides a Pt5Co catalyst prepared by the preparation method of the Pt5Co catalyst.

[0017] The present invention also provides the application of the Pt5Co catalyst in hydrogen production by hydrolysis.

[0018] The beneficial effects of the present invention are as follows: The Pt5Co catalyst provided by the present invention uses a carbon support with a high specific surface area as the substrate, and the material has a large defect density and a specific surface area of 1368.1361 m 2 g-1 , the void volume is 2.559472 cm 3 g -1 , the larger the pore volume, the higher the adsorption capacity and the stronger the catalytic activity; after loading Pt5Co nanoparticles, the Pt5Co catalyst exhibits excellent catalytic activity and stability in the hydrogen evolution reaction (HER), with an overpotential of 32 mV (10 mA cm-2) and a Tafel slope of 31.3 mV dec -1 , showing good application potential. Description of the Drawings

[0019] Figure 1 is the Raman data graph of the carbon support prepared in Example 1;

[0020] Figure 2 is the adsorption-desorption curve and pore size distribution graph of the carbon support prepared in Example 1;

[0021] Figure 3 is the TEM graph of the Pt5Co catalyst prepared in Example 1;

[0022] Figure 4 is the TEM grain size of the Pt5Co catalyst prepared in Example 1 Figure 1 ;

[0023] Figure 5 is the TEM grain size of the Pt5Co catalyst prepared in Example 1 Figure 2 ;

[0024] Figure 6 is the XRD graph of the Pt5Co catalyst prepared in Example 1;

[0025] Figure 7 is the HER performance polarization curve graph of the Pt5Co catalyst prepared in Example 1;

[0026] Figure 8 is the HER performance EIS curve graph of the Pt5Co catalyst prepared in Example 1;

[0027] Figure 9 is the Tafel curve graph of the Pt5Co catalyst prepared in Example 1. Detailed Description of the Invention

[0028] The following describes the specific implementation manners of the present invention in detail with reference to the examples.

[0029] Example 1

[0030] A preparation method of a Pt5Co catalyst includes the following steps:

[0031] S1: Mix H2PtCl6 and CoCl2 in a molar ratio of Pt:Co = 5:1, and then dissolve them in ethanol to prepare a precursor solution with a concentration of 0.05 mol / L;

[0032] S2: Place the carbon black material ketjenblack EC - 600JD in a CO2 atmosphere (flow rate 100 sccm), keep it at 700 °C for 6 h to obtain a pretreated carbon black material; Mix the pretreated carbon black material and melamine in a mass ratio of 5:1, and then keep it at 700 °C for 1 h in an argon atmosphere to obtain a carbon support;

[0033] S3: Add the carbon support to the precursor solution (the material ratio of the carbon support to the precursor solution is 1 g:2 mL), ultrasonically mix evenly, let it stand for 36 h until the ethanol volatilizes, add deionized water for freezing after standing, to obtain a frozen sample; Then freeze - dry the frozen sample to obtain a crude product;

[0034] S4: Heat the crude product at a heating rate of 105 K s -1 to 1100 °C, and then heat for 50 mS to obtain the Pt5Co catalyst.

[0035] Example 2

[0036] A preparation method of a Pt5Co catalyst, comprising the following steps:

[0037] S1: Mix H2PtCl6 and Co(NO3)2·6H2O in a molar ratio of Pt:Co = 5:1, and then dissolve them in ethanol to prepare a precursor solution with a concentration of 0.04 mol / L;

[0038] S2: Place the carbon black material ketjenblack EC - 600JD in a CO2 atmosphere (flow rate 50 sccm), keep it at 750 °C for 4 h to obtain a pretreated carbon black material; Mix the pretreated carbon black material and melamine in a mass ratio of 4:1, and then keep it at 750 °C for 1 h in an argon atmosphere to obtain a carbon support;

[0039] S3: Add the carbon support to the precursor solution (the material ratio of the carbon support to the precursor solution is 1 g:2 mL), ultrasonically mix evenly, let it stand for 24 h until the ethanol volatilizes, add deionized water for freezing after standing, to obtain a frozen sample; Then freeze - dry the frozen sample to obtain a crude product;

[0040] S4: Heat the crude product at a heating rate of 105 K s -1 to 1000 °C, and then heat for 50 mS to obtain the Pt5Co catalyst.

[0041] Example 3

[0042] A preparation method of a Pt5Co catalyst, comprising the following steps:

[0043] S1: Mix H2PtCl6 and CoCl2 in a molar ratio of Pt:Co = 5:1, and then dissolve them in ethanol to prepare a precursor solution with a concentration of 0.06 mol / L;

[0044] S2: Place the carbon black material ketjenblack EC-600JD in a CO2 atmosphere (flow rate 200 sccm), keep it at 650 °C for 8 h to obtain a pretreated carbon black material; Mix the pretreated carbon black material and melamine in a mass ratio of 6:1, and then keep it at 650 °C for 1 h in an argon atmosphere to obtain a carbon support;

[0045] S3: Add the carbon support to the precursor solution (the material ratio of the carbon support to the precursor solution is 1 g:2 mL), ultrasonically mix evenly, let it stand for 45 h until the ethanol volatilizes, add deionized water for freezing after the standing ends to obtain a frozen sample; Then freeze-dry the frozen sample to obtain a crude product;

[0046] S4: Heat the crude product at a heating rate of 105 K s -1 to 1200 °C, and then heat for 50 mS to obtain the Pt5Co catalyst.

[0047] The Pt5Co catalysts prepared in Examples 1 to 3 have similar performance effects, and the Pt5Co catalyst prepared in Example 1 is used in subsequent experiments.

[0048] Experimental Example 1

[0049] Analysis of the performance of the carbon support 1: Analyze the carbon support prepared in Example 1 using a Raman spectrometer, and the analysis results are as Figure 1 shown, I(D) / I(G) = 1.13, indicating that the carbon support has a medium degree of defects or disorder, and the defect sites can serve as active sites to promote the adsorption of reactants and enhance the catalytic activity.

[0050] Experimental Example 2

[0051] Analysis of the performance of the carbon support 2: Analyze the carbon support prepared in Example 1 using a material adsorption analyzer, and its adsorption-desorption curve and pore size distribution diagram are as Figure 2 shown, the specific surface area is 1368.1361 m 2 g -1 , the pore volume is 2.559472 cm 3 g -1 , and the larger the pore volume, the higher the adsorption capacity and the enhanced catalytic activity.

[0052] Experimental Example 3

[0053] Microscopic analysis: The Pt5Co catalyst prepared in Example 1 was analyzed using a transmission electron microscope, and the results are as follows Figures 3 - 5 shown. It can be seen from the TEM image in Figure 3 that the Pt5Co nanoparticles are evenly distributed, while from the TEM grain size image in Figures 4 - 5 it can be seen that the average particle size of the synthesized Pt5Co nanoparticles is about 5 nm, indicating the stability of the Pt5Co catalyst.

[0054] Experimental Example 4

[0055] Catalyst composition detection: The Pt5Co catalyst prepared in Example 1 was analyzed by X-ray diffraction, and the results are as follows Figure 6 shown. Peaks of Pt5Co (PDF#97-010-7047) appeared in the XRD pattern, indicating that the synthesized Pt5Co nanoparticles were successfully loaded on the carbon support.

[0056] Experimental Example 5

[0057] Electrochemical test: The Pt5Co catalyst prepared in Example 1 was loaded on carbon paper as the working electrode, a saturated calomel electrode as the reference electrode, a platinum sheet as the counter electrode, and 0.5 M H2SO4 as the electrolyte. The experimental results are as follows Figures 7 - 9 shown; First, an LSV test was performed. The scanning range was usually from 0 V to -0.5 V, and the scanning rate was 2 mV s -1 . The experimental results are as follows Figure 7 shown. At 10 mA cm -2 the overpotential was 32 mV, indicating that the prepared Pt5Co nanoparticles exhibited excellent catalytic activity in the hydrogen evolution reaction (HER). Then, an EIS test was performed at a potential of -0.24 V, and the results are as follows Figure 8 shown. Rct was 6.8 Ω. The smaller Rct is, the faster the electron transfer of the unit active site is, indicating that the Pt5Co catalyst provided by the present invention has excellent catalytic activity; Calculate the Tafel slope of the Pt5Co catalyst. Its Tafel curve is as follows Figure 9 shown. The Tafel slope was 31.3 mV dec -1 . A catalyst with a small slope can reach a high current density at a low overpotential, and the performance is better, indicating that the Pt5Co catalyst provided by the present invention exhibits good application potential.

[0058] Although the specific implementation manners of the present invention have been described in detail in combination with the embodiments, it should not be construed as a limitation on the protection scope of this patent. Within the scope described in the claims, various modifications and deformations that can be made by those skilled in the art without creative labor still fall within the protection scope of this patent.

Claims

1. A preparation method of a Pt5Co catalyst, characterized in that, It includes the following steps: S1: Mix a Pt source and a Co source in a molar ratio of Pt:Co = 5:1, and then dissolve them in ethanol to obtain a precursor solution; S2: Keep the carbon black material in a CO2 atmosphere at 650 - 750 °C for 4 - 8 h to obtain a pretreated carbon black material; Mix the pretreated carbon black material and melamine in a mass ratio of 4 - 6:1, and then keep it in an inert atmosphere at 650 - 750 °C for 1 h to obtain a carbon support; S3: Add the carbon support to the precursor solution, ultrasonically mix it evenly, let it stand for 24 - 48 h, add deionized water for freezing after the standing ends to obtain a frozen sample; then freeze-dry the frozen sample to obtain a crude product; S4: Perform Joule heating on the crude product to obtain the Pt5Co catalyst.

2. The preparation method of the Pt5Co catalyst according to claim 1, characterized in that: The Pt source is H2PtCl6, and the Co source is CoCl2 or Co(NO3)2·6H2O.

3. The preparation method of the Pt5Co catalyst according to claim 1, wherein: The concentration of the precursor solution is 0.04 - 0.06 mol / L.

4. The preparation method of the Pt5Co catalyst according to claim 1, characterized in that: The carbon black material is conductive carbon black.

5. The preparation method of the Pt5Co catalyst according to claim 1, wherein: The material ratio of the carbon support to the precursor solution is 1 g:2 mL.

6. The preparation method of the Pt5Co catalyst according to claim 1, characterized in that: The Joule heating is to heat up to 1000 - 1200 °C at a heating rate of 105 K / s -1 and then heat for 50 mS.

7. The Pt5Co catalyst prepared by the preparation method of the Pt5Co catalyst according to any one of claims 1 - 6.

8. The application of the Pt5Co catalyst according to claim 7 in hydrogen production by hydrolysis.

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