Method for producing hydrogen by using platinum-based alloy catalyst

Abstract

The invention belongs to the technical field of new energy for hydrogen production through water electrolysis, and particularly relates to a method for producing hydrogen through a platinum-based alloy catalyst. The method comprises the following steps: uniformly mixing a platinum-based alloy catalyst and a solvent to form catalyst slurry; dripping the catalyst slurry on carbon paper to prepare a working electrode, introducing a magnetic field by taking silver chloride as a reference electrode and a carbon rod as a counter electrode, and electrolyzing water in an electrolytic tank under an acidic condition to separate hydrogen; after the magnetic field is closed, water electrolysis is continued for hydrogen evolution. According to the method provided by the invention, the platinum-based alloy catalyst shows better hydrogen evolution catalytic performance when the platinum-based alloy catalyst is introduced into a magnetic field for testing, the catalytic performance is further improved when the magnetic field is closed for testing, and the catalytic performance is in positive correlation with the introduced magnetic field intensity along with continuous increase of the introduced magnetic field intensity. Therefore, the ferromagnetism enhancement of the platinum-based alloy catalyst has a wide application prospect in the field of acidic hydrogen evolution.

Description

Technical Field

[0001] The present invention belongs to the new energy technology field of hydrogen production by electrolyzing water, and particularly relates to a method for producing hydrogen by using a platinum-based alloy catalyst. Background Art

[0002] As an energy carrier and chemical raw material, hydrogen is an ideal green energy source to replace fossil fuels. Electrochemical hydrolysis is one of the most promising energy conversion technologies for hydrogen production. This process only requires water and electrical energy and does not produce any greenhouse gases or harmful pollutants. Especially when renewable energy (such as solar energy, wind energy) is used to drive the electrolysis of water, the hydrogen production process is completely zero-emission, which is regarded as a green and sustainable way of hydrogen production. The by-product of electrolytic water hydrogen evolution is oxygen, and the purity of hydrogen is very high. Compared with other hydrogen production methods (such as natural gas reforming method), the hydrogen purity of electrolyzing water can reach more than 99.999%, which is suitable for applications requiring high-purity hydrogen, such as fuel cells, electrolysis reactions, electronic industries, etc.

[0003] In the existing methods of electrocatalytic hydrogen evolution, the performance of the catalyst depends on its adsorption energy (ΔG H* ) for hydrogen intermediates (H*). Ideally, ΔG H* should be close to zero. Platinum itself shows good stability in acidic media, but in a high-voltage and strong oxidation environment, the platinum catalyst may undergo a slight oxidation reaction, resulting in a decrease in surface activity. By alloying platinum with other metals (such as cobalt, iron, nickel, etc.) to form a platinum-based alloy catalyst, the usage amount of platinum can be reduced while maintaining high catalytic activity. Metal alloying can not only adjust the electronic structure of platinum and optimize the hydrogen adsorption free energy (ΔG H* ), but also improve the stability and anti-poisoning ability of the catalyst.

[0004] As a ferromagnetic material, the platinum-based alloy catalyst has unique spin polarization effects and magnetic field effects in electrocatalytic reactions. On the one hand, it can optimize the adsorption energy of reaction intermediates and reduce the reaction energy barrier. On the other hand, it can promote charge transfer and accelerate the reaction kinetics. In addition, an external magnetic field can significantly improve the hydrogen evolution performance of ferromagnetic catalysts, providing a new way for optimizing catalytic reactions. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for enhancing the ferromagnetic property of a platinum-based alloy catalyst in the hydrogen evolution reaction and its application in view of the deficiencies of the prior art. The present invention realizes efficient hydrogen evolution driven under acidic conditions by making the ferromagnetic property of the metal alloyed catalyst enhanced by introducing a magnetic field and then turning off the magnetic field during the hydrogen evolution performance test.

[0006] To solve the above technical problems, the present invention discloses a method for producing hydrogen using a platinum-based alloy catalyst, comprising the following steps:

[0007] S1. Mix the platinum-based alloy catalyst and the solvent evenly to form a catalyst slurry;

[0008] S2. Drop the catalyst slurry onto carbon paper to make a working electrode, use silver chloride as a reference electrode and a carbon rod as a counter electrode, introduce a magnetic field, and electrolyze water to produce hydrogen in an acidic condition electrolytic cell;

[0009] S3. Continue to electrolyze water to produce hydrogen after turning off the magnetic field.

[0010] Wherein, the platinum-based alloy catalyst is L10–PtM, and M includes any one of Fe, Co, and Ni.

[0011] Specifically, the preparation method of the L10–PtM includes the following steps: Mix platinum acetylacetonate and transition metal acetylacetonate evenly and then heat, centrifuge after cooling to obtain the A1 phase PtM, disperse the A1 phase PtM in hexane, then add it to the hexane solution of carbon black, ultrasonicate and dry, and obtain L10–PtM after annealing treatment;

[0012] Wherein, the molar ratio of platinum acetylacetonate to transition metal acetylacetonate is 1:(1–1.5); for the heating, the temperature is 300 °C; the solid-liquid ratio of the A1 phase PtM to hexane is 1 g:40 mL; the solid-liquid ratio of carbon black to hexane is 1 g:100 mL; for the annealing, the condition is annealing at 500 °C for 6 hours in a H2 / Ar atmosphere;

[0013] Preferably, the transition metal acetylacetonate includes any one of iron acetylacetonate, cobalt acetylacetonate, and nickel acetylacetonate.

[0014] Wherein, the solvent is a mixed solution of ethanol, Nafion solution, and deionized water; the volume ratio of ethanol, Nafion solution, and deionized water is 10:1:1;

[0015] Preferably, the concentration of the Nafion solution is 10 wt%.

[0016] Wherein, the solid-liquid ratio of the platinum-based alloy catalyst to the solvent is 1 g:(15–20) mL;

[0017] Preferably, the solid-liquid ratio of the platinum-based alloy catalyst to the solvent is 1 g:15.75 mL.

[0018] Wherein, the single dosage of the catalyst slurry is 40 μL.

[0019] Among them, the acidic condition is provided by an H2SO4 solution; the concentration of the H2SO4 solution is 0.5 mol / L.

[0020] Among them, the magnetic field has an intensity of 75 - 600 mT;

[0021] Preferably, the magnetic field has an intensity of 75 mT, 150 mT, 300 mT, 600 mT.

[0022] Beneficial effects:

[0023] Compared with the performance test without applying a magnetic field, when the performance test is carried out under the conditions of applying a magnetic field and turning off the magnetic field, better hydrogen evolution catalytic performance is shown during the application of the magnetic field test, and there is a further improvement in catalytic performance during the turning off of the magnetic field test. At the same time, as the intensity of the applied magnetic field continuously increases, the catalytic performance is positively correlated with the intensity of the applied magnetic field. Therefore, the use of the ferromagnetic enhancement of the platinum-based alloy catalyst has broad application prospects in the field of acidic hydrogen evolution. Description of the drawings

[0024] The following further specific descriptions of the present invention will be made in conjunction with the drawings and specific embodiments, and the above and / or other advantages of the present invention will become clearer.

[0025] Figure 1 XRD pattern of the L10–PtCo alloy nanoparticle catalyst prepared in Example 1.

[0026] Figure 2 VSM pattern of the L10–PtCo alloy nanoparticle catalyst prepared in Example 1.

[0027] Figure 3 High-magnification transmission electron microscope (HRTEM) image of the L10–PtCo alloy nanoparticle catalyst prepared in Example 1.

[0028] Figure 4 Lattice spacing image of the L10–PtCo alloy nanoparticle catalyst prepared in Example 1.

[0029] Figure 5 Linear sweep voltammetry (LSV) curves of the L10–PtCo alloy nanoparticle catalyst prepared in the example at magnetic field intensities of 0 mT, 75 mT, 150 mT, 300 mT, 600 mT and with the magnetic field turned off for electrochemical hydrogen evolution. Specific embodiments

[0030] In the following embodiments, the experimental methods are all conventional methods unless otherwise specified; the reagents and materials can all be obtained from commercial sources unless otherwise specified.

[0031] In the following examples, the hydrogen evolution performance was tested in an H-type electrolytic cell separated by a treated Nafion 117 membrane at room temperature using a CHI660E electrochemical workstation. A standard three-electrode system was adopted to measure the linear sweep voltammetry (LSV) curve of the catalyst. The potential test range was -0.4 V to 0.2 V (reversible hydrogen electrode potential). The performance of the catalyst was reflected by the current density at fixed overpotentials (η = -0.2 V and η = 0.2 V). The greater the current density, the higher the catalytic activity.

[0032] Example 1:

[0033] This example provides a method for preparing L10–PtM alloy nanoparticles, which includes the following steps:

[0034] 0.5 mmol of platinum acetylacetonate, 0.56 mmol of cobalt acetylacetonate, and 20 mL of oleylamine were mixed evenly under the protection of inert gas and heated to 300 °C for 1 hour. After cooling to room temperature, 80 mL of a mixed solution with a liquid phase ratio of hexane to ethanol of 1:7 was added for centrifugation to obtain A1-phase PtCo (A1–PtCo) alloy nanoparticles, which were dispersed in hexane at a solid-liquid ratio of 1 g:40 mL. 0.4 g of carbon black was ultrasonically treated in 40 mL of hexane for 20 minutes, and then the A1–PtCo nanoparticle dispersion was added dropwise thereto. After mixing, ultrasonic treatment was continued for 1 hour, followed by drying and annealing in an H2 / Ar atmosphere at 500 °C for 6 hours to finally obtain L10–PtCo alloy nanoparticles.

[0035] The L10–PtCo alloy nanoparticle catalyst was characterized by X-ray diffraction analysis. Figure 1 is the XRD pattern of the L10–PtCo alloy nanoparticle catalyst. It can be seen from the figure that a superlattice peak appears at 33.4°, meeting the characteristics of the L10 structure.

[0036] The magnetic properties of the L10–PtCo alloy nanoparticle catalyst were characterized by a vibrating sample magnetometer. Figure 2 is the VSM pattern of the L10–PtCo alloy nanoparticle catalyst. It can be seen from the figure that the L10 structure has a relatively large coercivity.

[0037] The L10–PtCo alloy nanoparticle catalyst was characterized by high-resolution transmission electron microscopy. Figure 3 is the HRTEM pattern of the L10–PtCo alloy nanoparticle catalyst. It can be seen from the figure that the L10–PtCo alloy nanoparticles are spherical and evenly dispersed. Figure 4 is the lattice spacing pattern of the L10–PtCo alloy nanoparticle catalyst. It can be seen from the figure that the lattice spacing meets the (200) and (111) planes of L10–PtCo.

[0038] Cobalt acetylacetonate was replaced with iron acetylacetonate and nickel acetylacetonate respectively, and other preparation conditions remained unchanged, and L10–PtFe and L10–PtNi were prepared.

[0039] Example 2:

[0040] This example provides a method for producing hydrogen using an L10–PtCo alloy nanoparticle catalyst, which includes the following steps:

[0041] (1) Take 0.4 g of the L10–PtCo alloy nanoparticle catalyst and add 300 μL of ethanol and 30 μL of a 10 wt% Nafion solution in sequence. After ultrasonic treatment for 20 minutes, add 300 μL of deionized water and then perform ultrasonic treatment for another 20 minutes to form a uniformly dispersed catalyst slurry.

[0042] (2) Take 40 μL of the catalyst slurry obtained in step (1) and drop it on the carbon paper for drying, and drop it once on both the front and back sides.

[0043] (3) Use an H-type electrolytic cell for electrochemical hydrogen evolution testing. Among them, the working electrode (cathode) is the carbon paper loaded with the catalyst, the reference electrode is the silver chloride electrode, and the counter electrode is the carbon rod. Place 0.5 mol / L H2SO4 solution in the H-type electrolytic cell.

[0044] (4) Place the sample prepared in step (2) under the reaction conditions of step (3) for testing; specifically, when a 300 mT magnetic field is introduced into the device, the hydrogen evolution performance test is carried out simultaneously.

[0045] (5) Immediately perform the hydrogen evolution performance test on the device after the magnetic field is turned off after the test in step (4) is completed.

[0046] Example 3:

[0047] Replace the L10–PtCo alloy nanoparticle catalyst in Example 2 with an L10–PtFe alloy nanoparticle catalyst, and keep the other steps unchanged, then a method for producing hydrogen using an L10–PtFe alloy nanoparticle catalyst is obtained.

[0048] Example 4:

[0049] Replace the L10–PtCo alloy nanoparticle catalyst in Example 2 with an L10–PtNi alloy nanoparticle catalyst, and keep the other steps unchanged, then a method for producing hydrogen using an L10–PtNi alloy nanoparticle catalyst is obtained.

[0050] Example 5:

[0051] Replace the magnetic field strength in step (4) of Example 2 with 75 mT, and keep the other steps unchanged, then a method for producing hydrogen using an L10–PtCo alloy nanoparticle catalyst is obtained.

[0052] Example 6:

[0053] Replace the magnetic field strength in step (4) of Example 2 with 150 mT, and keep the other steps unchanged, then a method for producing hydrogen using an L10–PtCo alloy nanoparticle catalyst is obtained.

[0054] Example 7:

[0055] Replace the magnetic field strength in step (4) of Example 2 with 300 mT, and keep the other steps unchanged, then a method for producing hydrogen using an L10–PtCo alloy nanoparticle catalyst is obtained.

[0056] Example 8:

[0057] Replace the magnetic field strength in step (4) of Example 2 with 600 mT, and keep the other steps unchanged, then a method for producing hydrogen using an L10–PtCo alloy nanoparticle catalyst is obtained.

[0058] Comparative Example 1:

[0059] This comparative example provides a method for producing hydrogen using an L10–PtCo alloy nanoparticle catalyst, which includes the following steps:

[0060] (1) Take 0.4 g of the L10–PtCo alloy nanoparticle catalyst, add 300 μL of ethanol and 30 μL of Nafion solution, ultrasonicate for 20 minutes, then add 300 μL of deionized water and ultrasonicate for another 20 minutes to form a uniformly dispersed catalyst slurry;

[0061] (2) Take 40 μL of the catalyst slurry obtained in step (1) and drop it onto the carbon paper for drying, dropping once on each side;

[0062] (3) Use an H-type electrolytic cell for electrochemical hydrogen evolution testing. The working electrode (cathode) is the carbon paper loaded with the catalyst, the reference electrode is the silver chloride electrode, and the counter electrode is the carbon rod. Place 0.5 mol / L H2SO4 solution in the H-type electrolytic cell;

[0063] (4) Place the sample prepared in step (2) under the reaction conditions of step (3) for testing;

[0064] (5) Perform hydrogen evolution performance testing on the electrode test system prepared in step (4).

[0065] The hydrogen evolution performance results of Examples 2-8 and Comparative Example 1 are shown in Table 1. As can be seen from Table 1, among the different L10–PtM (L10–PtM, M: Fe, Co, Ni) alloy nanoparticle catalysts in Examples 2-4, at the same magnetic field strength and the same potential (E RHE =-0.2 V), the current passing through L10–PtCo is larger than that of L10–PtFe and L10–PtNi.

[0066] Figure 5 FIG. is the linear sweep voltammogram of the L10–PtCo alloy nanoparticle catalyst in Examples 5-8 and Comparative Example 1 under different magnetic field conditions. As can be seen from the results of Examples 5-8, the electrocatalytic hydrogen evolution performance of the L10–PtCo alloy catalyst under different magnetic field strengths shows obvious differences. Compared with the test without magnetic field in Comparative Example 1, when the potential is the same (E RHE =-0.2 V), performance tests are carried out under the conditions of applying magnetic field and turning off the magnetic field. When the applied magnetic field is 600 mT, the current growth rates reach 39% and 61% respectively, showing better hydrogen evolution catalytic performance compared with the case without magnetic field. At the same time, as the applied magnetic field strength increases continuously, the catalytic performance is positively correlated with the applied magnetic field strength.

[0067] Combined with Table 1 and the results of Figure 5 , it can be seen from the performance comparison of Examples 2-8 that applying magnetic field can improve the catalytic performance of L10–PtM. However, after applying magnetic field for a period of time and then turning off the magnetic field, the catalytic performance of L10–PtM is further improved. The growth rate of the current after turning off the magnetic field compared with that after applying magnetic field reaches at least 11.42%, and in Example 3, it can reach up to 20.59% at most. The increase in current at the same potential after turning off the magnetic field of L10–PtM is more significant. The main reason is that when applying magnetic field, due to the uniformity of the direction of the external magnetic field, it is difficult to completely match the anisotropic catalyst surface, resulting in an insignificant improvement effect of magnetic catalysis. When the external magnetic field is removed, the surface and interface magnetic domains of the magnetized L10–PtM catalyst are highly consistent with its anisotropic catalyst surface. Therefore, this highly matched micro-local surface and interface and magnetic structure can more significantly improve the magnetic catalytic gain.

[0068] Table 1 is the comparison of hydrogen evolution performance of Examples 2-8 and Comparative Example 1

[0069]

[0070] The present invention provides an idea for a method of producing hydrogen using a platinum-based alloy catalyst. There are many methods and ways to specifically implement this technical solution. The above description is only a preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be implemented using existing technologies.

Claims

1. A method for producing hydrogen using a platinum-based alloy catalyst, characterized in that, It includes the following steps: S1. Mix the platinum-based alloy catalyst and the solvent evenly to form a catalyst slurry; S2. Drop the catalyst slurry onto the carbon paper to make a working electrode, use silver chloride as the reference electrode and a carbon rod as the counter electrode, introduce a magnetic field, and electrolyze water to produce hydrogen in an acidic condition electrolytic cell; S3. Continue to electrolyze water to produce hydrogen after turning off the magnetic field.

2. The method according to claim 1, wherein The platinum-based alloy catalyst is L10–PtM, where M includes any one of Fe, Co, and Ni.

3. The method according to claim 2, wherein The preparation method of the L10–PtM includes the following steps: Mix platinum acetylacetonate and transition metal acetylacetonate evenly and then heat, centrifuge after cooling to obtain the A1 phase PtM, disperse the A1 phase PtM in hexane, then add it to the hexane solution of carbon black, ultrasonicate and dry, and obtain L10–PtM after annealing treatment.

4. The method according to claim 1, wherein The solvent is a mixed solution of ethanol, Nafion solution and deionized water; the volume ratio of ethanol, Nafion solution and deionized water is 10:1:

1.

5. The method according to claim 4, wherein The concentration of the Nafion solution is 10 wt%.

6. The method according to claim 1, wherein The solid-liquid ratio of the platinum-based alloy catalyst and the solvent is 1 g:(15 - 20) mL.

7. The method according to claim 1, characterized in that, The single dosage of the catalyst slurry is 40 μL.

8. The method according to claim 1, wherein The acidic condition is provided by an H2SO4 solution; the concentration of the H2SO4 solution is 0.5 mol / L.

9. The method according to claim 1, wherein The magnetic field has an intensity of 75 - 600 mT.

10. The method according to claim 9, wherein The magnetic field has intensities of 75 mT, 150 mT, 300 mT, and 600 mT.

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