Hydrogen evolution catalyst and preparation method thereof

Abstract

The invention discloses a hydrogen evolution catalyst and a preparation method thereof, and belongs to the field of renewable energy sources. The preparation method of the hydrogen evolution catalyst comprises the following steps: dissolving chloroplatinic acid, adding glycerol into a system, and stirring until the glycerol is dissolved to obtain a mixed solution A; dissolving sodium borohydride in an alkaline solution, and stirring until the sodium borohydride is dissolved to obtain a mixed solution B; under a stirring state, slowly dropwise adding the mixed solution B into the mixed solution A, raising the temperature to a preset temperature for reaction, washing a black precipitate through a centrifugal machine after the reaction, and putting the black precipitate into a drying oven for drying treatment; and the dried powder is placed in a vacuum drying box to be subjected to heat treatment. The hydrogen evolution catalyst can be conveniently prepared with high quality through the method.

Description

Technical Field

[0001] The invention belongs to the field of renewable energy, and in particular relates to a hydrogen evolution catalyst and a preparation method thereof. Background Art

[0002] The research and application of renewable energy are constantly advancing. As a clean, efficient and flexible secondary energy source, hydrogen energy is an important medium to promote the clean and efficient use of traditional fossil energy and support the large-scale development of renewable energy. As components of the hydrogen energy industry chain, water electrolysis and fuel cells play an important guiding role in the green and low-carbon transformation of transportation, industry and other fields.

[0003] Platinum (Pt) nanomaterials have high activity and are therefore used as catalysts for hydrogen evolution in water electrolysis, catalytic combustion reactions in fuel cells, and in the field of using ion exchange membranes as separation media or electrolytes.

[0004] Platinum black is an extremely fine powder of metallic platinum. The preparation methods usually include impregnation-liquid phase reduction method, microwave heating method, microemulsion method, electrochemical method, etc.

[0005] However, the platinum black produced in current practice has low crystallinity, and many organic ligands and toxic substances are introduced during the preparation process, which makes it difficult to remove and is not conducive to large-scale expansion. Therefore, it is necessary to further optimize the preparation process to obtain a platinum black catalyst material suitable for large-scale production and with better hydrogen evolution catalytic activity and stability. Summary of the invention

[0006] The example of the present invention provides a hydrogen evolution catalyst and a preparation method thereof. The preparation method is simple to operate and is conducive to large-scale production and application. In addition, the platinum black catalyst prepared by the method has excellent crystallinity, hydrogen evolution catalytic activity and stability, and can therefore be applied to a water electrolysis hydrogen production electrolyzer.

[0007] The exemplary solution of the present invention is implemented as follows.

[0008] The present invention discloses a method for preparing a hydrogen evolution catalyst, comprising:

[0009] After dissolving chloroplatinic acid, add propylene glycol to the system and stir until dissolved to obtain a mixed solution A;

[0010] Dissolve sodium borohydride in an alkaline solution and stir until dissolved to obtain a mixed solution B;

[0011] Under stirring, slowly drop the mixed solution B into the mixed solution A, heat it to a preset temperature for reaction, and after the reaction, wash the black precipitate with a centrifuge and dry it in an oven;

[0012] The dried powder is placed in a vacuum drying oven for heat treatment.

[0013] According to some examples of the invention, chloroplatinic acid is crystalline and sodium borohydride is crystalline.

[0014] According to some examples of the present invention, the chloroplatinic acid is dissolved in water, the concentration of the chloroplatinic acid is 0.01 mol / L to 0.2 mol / L, and the concentration of glycerol is 0.005 mol / L to 0.1 mol / L.

[0015] According to some examples of the present invention, the alkaline solution is a sodium hydroxide solution, the concentration of the sodium hydroxide solution is 0.010 mol / L to 1.0 mol / L, and the concentration of sodium borohydride is 0.05 mol / L to 1 mol / L.

[0016] According to some examples of the present invention, the volume ratio of the mixed liquid A to the mixed liquid B is 1:1.

[0017] According to some examples of the present invention, the volume of the solution after the mixed solution A and the mixed solution B is 10-1000 mL.

[0018] According to some examples of the present invention, the black precipitate is washed three times with pure water and three times with ethanol.

[0019] According to some examples of the present invention, the drying process is as follows: the drying temperature is 40-60° C., and the drying time is 12-24 hours.

[0020] According to some examples of the present invention, the heat treatment temperature is 200-400° C., the heat treatment time is 1-3 hours, and the heat treatment method is vacuum heat treatment.

[0021] The present invention also describes a hydrogen evolution material obtained by implementing the above method for preparing the hydrogen evolution catalyst.

[0022] Compared with the prior art, the preparation method described in the present invention has at least the following effects:

[0023] 1. In the present invention, glycerol is added to the reaction solution to effectively disperse the platinum ions on the -OH chains, thereby avoiding aggregation of platinum particles and facilitating the formation of uniformly dispersed platinum particles.

[0024] 2. The present invention adopts a vacuum heat treatment method to further process the platinum black particles obtained by the impregnation reduction method, thereby increasing the crystallinity of the platinum black catalyst, which is of great significance to the improvement of the catalytic activity and stability of hydrogen evolution.

[0025] 3. The method for preparing platinum black provided by the present invention is simple to operate, does not introduce other impurities, and the operation of dissolving sodium borohydride crystals in sodium hydroxide solution avoids the large-scale release of hydrogen. It has high safety and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] For a clearer explanation, the following briefly introduces the drawings required for the description.

[0027] Figure 1 This is the XRD diagram of the sample of Example 1 of the present invention;

[0028] Figure 2 This is a SEM image of a sample of Example 1 of the present invention;

[0029] Figure 3 The electrochemical performance test curves of the samples of Example 1, Example 2 and Example 3 of the present invention;

[0030] Figure 4 This is a sample stability test curve of Example 1 of the present invention;

[0031] Figure 5 Schematic diagram of the process for preparing platinum black in the examples of the present invention. DETAILED DESCRIPTION

[0032] Platinum black is a very fine powder of metal platinum (element symbol Pt) with a large specific surface area. In appearance, platinum black is black. Platinum black is chemically stable, insoluble in water and inorganic acids, and does not react with general strong acids, alkalis and other reagents at room temperature. However, platinum black is soluble in aqua regia and can also react with concentrated sulfuric acid when heated.

[0033] Platinum black particles are small and have a large specific surface area. A large number of surface atoms of platinum black are in an unsaturated state, so it has a high surface energy and can interact strongly with gas molecules, thus having a strong adsorption capacity for gases such as hydrogen and oxygen. For example, platinum black can adsorb hydrogen equivalent to hundreds of times its own volume.

[0034] There are a large number of active sites such as defects, steps and edges on the surface of platinum black, and these sites have low atomic coordination numbers, high electron cloud density and high chemical activity, so they can easily form chemical bonds with reactant molecules, reduce the activation energy of the reaction, and thus show good catalytic activity.

[0035] Based on its usage, platinum black can be used as a catalyst, electrode material, electronic material and gas absorbent.

[0036] The purpose of the present invention is to achieve large-scale production of platinum black.

[0037] A major obstacle to large-scale production may be:

[0038] For example, the manufacturing process of platinum black is complicated and difficult to operate. For example, a large amount of toxic and harmful chemical raw materials are needed in the manufacturing process of platinum black, which may cause great harm to human body or equipment. For example, the yield of platinum black is low. For example, the performance of the manufactured platinum black is poor.

[0039] In the present invention, a platinum black production which is easy to scale up due to simplified process is realized, and such platinum black has high crystallinity, hydrogen evolution catalytic activity and stability, and can be applied to water electrolysis hydrogen production electrolyzer.

[0040] In the present invention, the above manufacturing method mainly includes mixing two prefabricated reagents for reaction and then performing heat treatment.

[0041] For example, in a specific example, the manufacturing method includes the following steps, namely step (1), step (2), step (3), and step (4), see Figure 5 .

[0042] Step (1) After dissolving chloroplatinic acid crystals (using water as solvent), propylene glycol is added to the system and stirred until dissolved to obtain a mixed solution A.

[0043] Among them, the concentration of chloroplatinic acid is 0.01 mol / L to 0.2 mol / L, and the corresponding concentration of glycerol is 0.005 mol / L to 0.1 mol / L.

[0044] By using propylene glycol, platinum ions can be effectively dispersed on the -OH chain, avoiding the aggregation of platinum particles and facilitating the formation of uniformly dispersed platinum particles.

[0045] Step (2) dissolving sodium borohydride crystals in sodium hydroxide solution, stirring until dissolved to obtain a mixed solution B.

[0046] The concentration of the sodium hydroxide solution is 0.01 mol / L to 1.0 mol / L, and the concentration of the sodium borohydride is 0.05 mol / L to 1 mol / L.

[0047] Step (3) under stirring, slowly dropwise add the mixed solution B into the mixed solution A, raise the temperature to 80°C and react for a period of time, wash the black precipitate with a centrifuge, and place it in an oven for drying.

[0048] The volume ratio of the mixed solution A to the mixed solution B is 1:1, and the volume of the obtained solution is 10-1000 mL. The temperature is raised to 80° C. and the reaction time is 60 min to 180 min.

[0049] Step (4) The dried powder is placed in a vacuum drying oven for heat treatment to obtain a platinum black hydrogen evolution catalyst.

[0050] The drying conditions are as follows: drying temperature of 40°C to 60°C, drying time of 12h to 24h, heat treatment temperature of 200-400°C, heat treatment time of 1-3h, and vacuum heat treatment.

[0051] In this step, the vacuum heat treatment method is used to further process the platinum black particles obtained by the impregnation reduction method, thereby increasing the crystallinity of the platinum black catalyst, which is of great significance for improving the catalytic activity and stability of hydrogen evolution.

[0052] Some specific examples are given below.

[0053] Example 1

[0054] After dissolving the chloroplatinic acid crystals, glycerol is added to the system, and mixed solution A is obtained after stirring until dissolved, wherein the concentration of chloroplatinic acid is 0.1mol / L, the corresponding concentration of glycerol is 0.05mol / L, and the solution volume is 100mL. Sodium borohydride crystals are dissolved in sodium hydroxide solution, and mixed solution B is obtained after stirring until dissolved, wherein the concentration of sodium hydroxide solution is 1mol / L, the concentration of sodium borohydride is 0.5mol / L, and the solution volume is 100mL. Under stirring, mixed solution B is slowly added dropwise to mixed solution A, heated to 80℃ for 60min, and after the reaction is completed, the black precipitate is washed three times with pure water, washed three times with ethanol, and placed in an oven at 60℃ for 12h to obtain dry platinum black powder. The dried powder is placed in a vacuum drying oven, and the heat treatment temperature under vacuum is 300℃, and the heat treatment time is 1h. Finally, a platinum black hydrogen evolution catalyst is obtained.

[0055] Figure 1 and Figure 2 The XRD and SEM images of the platinum black catalyst obtained in Example 1. It can be seen from the figure that the prepared sample is pure platinum and the sample has a porous granular morphology.

[0056] HER polarization curve of the platinum black hydrogen evolution electrode obtained in Example 1 in 0.5 mol / L H2SO4 electrolyte.

[0057] The specific test method is to weigh 10 mg of platinum black catalyst, add 300 μL of pure water, 665 μL of ethanol and 35 μL of 5% Nafion solution in sequence, disperse evenly by ultrasonic, take 10 μL of the mixed slurry and drop it on a glassy carbon electrode with a diameter of 5 mm as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum sheet electrode as the counter electrode.

[0058] Figure 3The polarization curve of the platinum black hydrogen evolution catalyst obtained in the example is shown. The hydrogen evolution performance of the sample prepared in the example is close. At the potential of -0.7V (vs SCE), the current density can reach 450mA / cm2.

[0059] Figure 4 This is the constant voltage stability test curve of the working electrode prepared in Example 1 at a potential of -0.3 V (vs SCE), the corresponding current density is 60 mA / cm2, and it can run stably for 30,000 s without attenuation.

[0060] Example 2

[0061] After dissolving the chloroplatinic acid crystals, propylene glycol is added to the system, and mixed solution A is obtained after stirring until dissolved, wherein the concentration of chloroplatinic acid is 0.1 mol / L, the corresponding concentration of propylene glycol is 0.05 mol / L, and the solution volume is 10 mL. Sodium borohydride crystals are dissolved in sodium hydroxide solution, and mixed solution B is obtained after stirring until dissolved, wherein the concentration of sodium hydroxide solution is 1 mol / L, the concentration of sodium borohydride is 0.5 mol / L, and the solution volume is 10 mL. Under stirring, mixed solution B is slowly added dropwise to mixed solution A, heated to 80 ° C for 180 min, and after the reaction is completed, the black precipitate is washed three times with pure water, washed three times with ethanol, and placed in an oven at 60 ° C for 12 hours to obtain a dry platinum black powder. The dried powder is placed in a vacuum drying oven, and the heat treatment temperature under vacuum is 300 ° C, and the heat treatment time is 1 h. Finally, a platinum black hydrogen evolution catalyst is obtained.

[0062] Example 3

[0063] After dissolving the chloroplatinic acid crystals, glycerol is added to the system, and mixed solution A is obtained after stirring until dissolved, wherein the concentration of chloroplatinic acid is 0.1mol / L, the corresponding concentration of glycerol is 0.05mol / L, and the solution volume is 50mL. Sodium borohydride crystals are dissolved in sodium hydroxide solution, and mixed solution B is obtained after stirring until dissolved, wherein the concentration of sodium hydroxide solution is 1mol / L, the concentration of sodium borohydride is 0.5mol / L, and the solution volume is 50mL. Under stirring, mixed solution B is slowly added dropwise to mixed solution A, warmed to 80℃ for 60min, and after the reaction is completed, the black precipitate is washed three times with pure water, washed three times with ethanol, and placed in an oven at 60℃ for 12h to obtain dry platinum black powder. The dried powder is placed in a vacuum drying oven, and the heat treatment temperature under vacuum is 200℃, and the heat treatment time is 1h. Finally, a platinum black hydrogen evolution catalyst is obtained.

[0064] The above describes in detail the structure, features and effects of the present invention based on the embodiments shown in the drawings. The above are only preferred embodiments of the present invention, but the present invention is not limited to the scope of implementation shown in the drawings. Any changes made according to the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which still do not exceed the spirit covered by the description and drawings, should be within the protection scope of the present invention.

Claims

1. A method for preparing a hydrogen evolution catalyst, characterized in that: include: After dissolving chloroplatinic acid, add propylene glycol to the system and stir until dissolved to obtain a mixed solution A; Dissolve sodium borohydride in an alkaline solution and stir until dissolved to obtain a mixed solution B; Under stirring, slowly drop the mixed solution B into the mixed solution A, heat it to a preset temperature for reaction, and after the reaction, wash the black precipitate with a centrifuge and dry it in an oven; The dried powder is placed in a vacuum drying oven for heat treatment.

2. The method for preparing a hydrogen evolution catalyst according to claim 1, wherein Chloroplatinic acid is crystalline, and sodium borohydride is crystalline.

3. The method for preparing a hydrogen evolution catalyst according to claim 2, wherein: The chloroplatinic acid is dissolved in water, the concentration of the chloroplatinic acid is 0.01-0.2 mol / L, and the concentration of glycerol is 0.005-0.1 mol / L.

4. The method for preparing a hydrogen evolution catalyst according to claim 1, wherein The alkaline solution is a sodium hydroxide solution, the concentration of the sodium hydroxide solution is 0.01-1.0 mol / L, and the concentration of sodium borohydride is 0.05-1 mol / L.

5. The method for preparing a hydrogen evolution catalyst according to claim 1, characterized in that: The volume ratio of mixed solution A to mixed solution B is 1:

1.

6. The method for preparing a hydrogen evolution catalyst according to claim 1, characterized in that: The volume of the solution after mixing the mixed solution A and the mixed solution B is 10-1000 mL.

7. The method for preparing a hydrogen evolution catalyst according to claim 1, characterized in that: The black precipitate was washed three times with pure water and three times with ethanol.

8. The method for preparing a hydrogen evolution catalyst according to claim 1, characterized in that: The drying process is as follows: the drying temperature is 40-60°C and the drying time is 12-24h.

9. The method for preparing a hydrogen evolution catalyst according to claim 1, characterized in that: The heat treatment temperature is 200-400°C, the heat treatment time is 1-3h, and the heat treatment method is vacuum heat treatment.

10. A hydrogen evolution material obtained by implementing the preparation method of the hydrogen evolution catalyst according to any one of claims 1 to 9.

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