Preparation Method of Hydrogen Evolution Catalyst and Its Application in Water Electrolysis for Hydrogen Production

Abstract

The present invention relates to the technical field of hydrogen evolution catalysts, and discloses a preparation method of a hydrogen evolution catalyst and its application in electrolytic water hydrogen production. The spiro-pentaerythritol bisphosphoryl dipyrrole cross-linked copolymer of the present invention is carbonized to form nitrogen-doped porous carbon, and the phosphorus element in the matrix reacts with Mo ions to in-situ generate nano-MoP inside the nitrogen-doped porous carbon, so that nano-MoP is uniformly distributed in the matrix of the nitrogen-doped porous carbon. The obtained hydrogen evolution catalyst uses nitrogen-doped porous carbon as a carrier, with uniformly distributed nano-MoP inside, has excellent catalytic activity, the specific surface area of the porous carbon is large, contains a large number of porous structures, and has excellent conductivity after nitrogen doping, more active sites for electrochemical reactions, better catalytic performance, and excellent hydrogen evolution activity. At a current density of 10 mA / cm<supgt;-2< / supgt;, the hydrogen evolution overpotential is only 112.4 - 181.3 mV.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen evolution catalysts, and specifically to a preparation method of a hydrogen evolution catalyst and its application in electrolytic water hydrogen production. Background Art

[0002] Hydrogen energy has the advantages of high efficiency, environmental friendliness, etc., and is the most promising new energy. Among them, electrochemically driven electrolytic water is an effective method for producing hydrogen. Electro-catalytic water decomposition to produce hydrogen plays an extremely important role in modern hydrogen energy, hydrogen fuel cells, metal-air batteries and other energy conversion technologies. However, in electrolytic water hydrogen production, the oxygen evolution reaction and hydrogen evolution reaction usually require the addition of catalysts to lower the energy barrier of the reaction and promote the reaction process of electrolytic water hydrogen production.

[0003] Currently, the main hydrogen evolution reaction catalysts include transition metal oxides, transition metal phosphides, transition metal sulfides, etc. Among them, molybdenum phosphide (MoP) has good chemical stability and catalytic activity, and has broad application prospects in electrolytic water hydrogen evolution reaction catalysts. For example, Chinese Patent CN111659430B discloses a preparation method of a low-platinum composite material for acidic electrolytic water hydrogen production. The phosphomolybdic acid / graphite oxide composite is subjected to high-temperature phosphidation and then dispersed in a chloroplatinic acid solution. The obtained low-platinum loaded molybdenum phosphide / graphene material exhibits excellent acidic electrolytic water hydrogen evolution activity. However, this catalyst requires expensive metal platinum and graphene oxide, with a high cost and is difficult to be industrially applied. Summary of the Invention

[0004] The technical problem solved by the present invention is: The present invention prepares a catalyst with high hydrogen evolution activity for electrolytic water hydrogen production.

[0005] Technical Solution: A preparation method of a hydrogen evolution catalyst:

[0006] Step (1), under an ice bath, add pyrrole and spiro pentaerythritol bisphosphoryl dipyrrole to a methanol solution of ferric chloride. After the reaction, distill the solution under reduced pressure, wash with distilled water and dry to obtain a spiro pentaerythritol bisphosphoryl dipyrrole cross-linked copolymer.

[0007] Step (2), add the spiro pentaerythritol bisphosphoryl dipyrrole cross-linked copolymer to an ethanol solution containing ammonium molybdate, mix well and perform ultrasonic treatment for 30 - 60 min. After filtration, place the mixture in a tubular furnace. Under a nitrogen atmosphere, control the heating rate at 3 - 6 °C / min, heat up to 700 - 850 °C, keep warm for 2 - 3 h, and then cool to obtain a hydrogen evolution catalyst.

[0008] Among them, in step (1), the mass concentration of the methanol solution of ferric chloride is 20 - 30 g / L.

[0009] Among them, in step (1), the mass of spiro pentaerythritol bisphosphoryl dipyrrole is 35-80% of the mass of pyrrole.

[0010] Among them, in step (1), the reaction is first stirred under an ice bath for 18-24 h, and then reacted at room temperature for 6-8 h.

[0011] Among them, in step (2), the mass concentration of the ammonium molybdate ethanol solution is 10-25 g / L.

[0012] Among them, the preparation method of spiro pentaerythritol bisphosphoryl dipyrrole is as follows: add pyrrole, spiro pentaerythritol bisphosphoryl dichloride, and catalyst triethylamine to any one of dichloromethane, acetonitrile, and 1,4-dioxane. The mass of pyrrole is 45-53% of the mass of spiro pentaerythritol bisphosphoryl dichloride; first react under an ice bath for 20-30 min, and then react at 30-55 °C for 6-10 h. After the reaction, the solution is distilled under reduced pressure, and the product is recrystallized with tetrahydrofuran to obtain spiro pentaerythritol bisphosphoryl dipyrrole.

[0013] Among them, the application of the hydrogen evolution catalyst in the electrolysis of water to produce hydrogen.

[0014] Technical effect: The spiro pentaerythritol bisphosphoryl dipyrrole prepared by the present invention contains two pyrrole structural units, can crosslink and polymerize with pyrrole to obtain a spiro pentaerythritol bisphosphoryl dipyrrole crosslinked copolymer with a three-dimensional porous structure. The crosslinked pyrrole copolymer contains a spiro pentaerythritol structure, has better char-forming property and high-temperature carbonization effect, and can be carbonized at high temperature to form nitrogen-doped porous carbon with a high specific surface area and excellent performance.

[0015] During the carbonization process of the mixture of the spiro pentaerythritol bisphosphoryl dipyrrole crosslinked copolymer and ammonium molybdate of the present invention, the spiro pentaerythritol bisphosphoryl dipyrrole crosslinked copolymer is carbonized to form nitrogen-doped porous carbon, and the phosphorus element in the matrix reacts with Mo ions to in-situ generate nano-MoP inside the nitrogen-doped porous carbon, so that the nano-MoP is uniformly distributed in the matrix of the nitrogen-doped porous carbon. The obtained hydrogen evolution catalyst uses nitrogen-doped porous carbon as a carrier, and uniformly distributed nano-MoP inside, has excellent catalytic activity, the specific surface area of the porous carbon is large, contains a large number of porous structures, and has excellent conductivity after nitrogen doping, more active sites for electrochemical reactions, better catalytic performance, is conducive to electron transfer during the electrolysis of water hydrogen evolution reaction process, thereby reducing the hydrogen evolution overpotential and having excellent hydrogen evolution activity. At a current density of 10 mA / cm -2 , the hydrogen evolution overpotential is only 112.4-181.3 mV. Description of the drawings

[0016] Figure 1 is the preparation reaction formula of spiro pentaerythritol bisphosphoryl dipyrrole.

[0017] Figure 2 It is the preparation principle of the spiro pentaerythritol bisphosphoryl dipyrrole cross-linked copolymer.

[0018] Figure 3 It is the scanning electron microscope image of the hydrogen evolution catalyst.

[0019] Figure 4 It is the linear sweep voltammetry curve of the hydrogen evolution catalyst. Specific implementation manners

[0020] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0021] Example 1

[0022] (1) Add 4.8 g of pyrrole, 10 g of spiro pentaerythritol bisphosphoryl dichloride, and 7.5 g of catalyst triethylamine to 150 mL of dichloromethane solvent. First, react at an ice bath for 20 min, and then react at 55 °C for 6 h. After the reaction, distill the solution under reduced pressure, and recrystallize the product with tetrahydrofuran to obtain spiro pentaerythritol bisphosphoryl dipyrrole.

[0023] (2) Under an ice bath, add 20 g of pyrrole and 7 g of spiro pentaerythritol bisphosphoryl dipyrrole to 400 mL of a methanol solution of 30 g / L ferric chloride. Stir and react for 18 h, and then react at room temperature for 6 h. After the reaction, distill the solution under reduced pressure, wash with distilled water and dry to obtain the spiro pentaerythritol bisphosphoryl dipyrrole cross-linked copolymer.

[0024] (3) Add 5 g of the spiro pentaerythritol bisphosphoryl dipyrrole cross-linked copolymer to 500 mL of an ethanol solution of 10 g / L ammonium molybdate ((NH4)6Mo7O 24 ·4H2O). After mixing, ultrasonically treat for 30 min. After filtration, place the mixture in a tubular furnace. Under a nitrogen atmosphere, control the heating rate at 3 °C / min, heat up to 700 °C, hold for 3 h, and cool to obtain the hydrogen evolution catalyst.

[0025] Example 2

[0026] (1) Add 5.3 g of pyrrole, 10 g of spiro pentaerythritol bisphosphoryl dichloride, and 7.2 g of catalyst triethylamine to 100 mL of 1,4-dioxane solvent. First, react at an ice bath for 20 min, and then react at 30 °C for 10 h. After the reaction, distill the solution under reduced pressure, and recrystallize the product with tetrahydrofuran to obtain spiro pentaerythritol bisphosphoryl dipyrrole.

[0027] (2) Under an ice bath, add 20 g of pyrrole and 10 g of spiro pentaerythritol bisphosphoryl dipyrrole to 500 mL of a methanol solution of ferric chloride with a mass concentration of 20 g / L, stir and react for 24 h, then react at room temperature for 6 h. After the reaction, distill the solution under reduced pressure, wash with distilled water and dry to obtain a spiro pentaerythritol bisphosphoryl dipyrrole crosslinked copolymer.

[0028] (3) Add 5 g of the spiro pentaerythritol bisphosphoryl dipyrrole crosslinked copolymer to 500 mL of an ethanol solution of ammonium molybdate with a mass concentration of 15 g / L, mix well and ultrasonically treat for 30 min. After filtration, place the mixture in a tube furnace. Under a nitrogen atmosphere, control the heating rate at 3 °C / min, heat up to 750 °C, keep warm for 3 h, and then cool to obtain a hydrogen evolution catalyst.

[0029] Example 3

[0030] (1) Add 4.5 g of pyrrole, 10 g of spiro pentaerythritol bisphosphoryl dichloride, and 7.8 g of the catalyst triethylamine to 100 mL of an acetonitrile solvent. First, react under an ice bath for 30 min, then react at 40 °C for 10 h. After the reaction, distill the solution under reduced pressure, and recrystallize the product with tetrahydrofuran to obtain spiro pentaerythritol bisphosphoryl dipyrrole.

[0031] (2) Under an ice bath, add 20 g of pyrrole and 13 g of spiro pentaerythritol bisphosphoryl dipyrrole to 500 mL of a methanol solution of ferric chloride with a mass concentration of 20 g / L, stir and react for 24 h, then react at room temperature for 6 h. After the reaction, distill the solution under reduced pressure, wash with distilled water and dry to obtain a spiro pentaerythritol bisphosphoryl dipyrrole crosslinked copolymer.

[0032] (3) Add 5 g of the spiro pentaerythritol bisphosphoryl dipyrrole crosslinked copolymer to 500 mL of an ethanol solution of ammonium molybdate with a mass concentration of 20 g / L, mix well and ultrasonically treat for 60 min. After filtration, place the mixture in a tube furnace. Under a nitrogen atmosphere, control the heating rate at 6 °C / min, heat up to 800 °C, keep warm for 2 h, and then cool to obtain a hydrogen evolution catalyst.

[0033] Example 4

[0034] (1) Add 4.5 g of pyrrole, 10 g of spiro pentaerythritol bisphosphoryl dichloride, and 7.8 g of the catalyst triethylamine to 100 mL of an acetonitrile solvent. First, react under an ice bath for 30 min, then react at 40 °C for 10 h. After the reaction, distill the solution under reduced pressure, and recrystallize the product with tetrahydrofuran to obtain spiro pentaerythritol bisphosphoryl dipyrrole.

[0035] (2) Under an ice bath, add 20 g of pyrrole and 16 g of spiro pentaerythritol bisphosphoryl dipyrrole to a 500 mL methanol solution of ferric chloride with a mass concentration of 20 g / L, stir and react for 24 h, then react at room temperature for 8 h. After the reaction, distill the solution under reduced pressure, wash with distilled water and dry to obtain a spiro pentaerythritol bisphosphoryl dipyrrole cross-linked copolymer.

[0036] (3) Add 5 g of the spiro pentaerythritol bisphosphoryl dipyrrole cross-linked copolymer to a 500 mL ethanol solution of ammonium molybdate with a mass concentration of 25 g / L, mix well and ultrasonically treat for 60 min. After filtration, place the mixture in a tube furnace. Under a nitrogen atmosphere, control the heating rate at 6 °C / min, heat up to 850 °C, keep warm for 2 h, and then cool to obtain a hydrogen evolution catalyst.

[0037] Comparative Example 1

[0038] (1) Under an ice bath, add 20 g of pyrrole to a 400 mL methanol solution of ferric chloride with a mass concentration of 30 g / L, stir and react for 18 h, then react at room temperature for 6 h. After the reaction, distill the solution under reduced pressure, wash with distilled water and dry to obtain polypyrrole.

[0039] (2) Add the polypyrrole to a 500 mL ethanol solution of ammonium molybdate with a mass concentration of 10 g / L, mix well and ultrasonically treat for 30 min. After filtration, place the mixture in a tube furnace. Under a nitrogen atmosphere, control the heating rate at 3 °C / min, heat up to 700 °C, keep warm for 3 h, and then cool to obtain a hydrogen evolution catalyst.

[0040] The hydrogen evolution activity of the hydrogen evolution catalyst was tested by the electrochemical performance of a three-electrode system.

[0041] Add 10 mg of the hydrogen evolution catalyst and 100 μL of Nafion solution to 2 mL of ethanol, mix well and coat the slurry on nickel foam, and dry to make a working electrode. Use a platinum plate electrode as the counter electrode and a Hg / HgO electrode as the reference electrode. A 1 mol / L KOH solution is used as the electrolyte. Test through an electrochemical workstation. The scanning rate is 5 mV / s. The test results are shown in the linear sweep voltammogram attached to the specification. Figure 4 For the hydrogen evolution catalysts prepared in Examples 1 to 4, at a current density of 10 mA / cm -2 the hydrogen evolution overpotential is only 112.4 - 181.3 mV.

[0042] This is because during the carbonization process of the mixture of spiro-pentaerythritol bisphosphoryl dipyrrole cross-linked copolymer and ammonium molybdate, the spiro-pentaerythritol bisphosphoryl dipyrrole cross-linked copolymer is carbonized to form nitrogen-doped porous carbon, and the phosphorus-containing element in the matrix reacts with Mo ions to in-situ generate nano-MoP inside the nitrogen-doped porous carbon, so that the nano-MoP is uniformly distributed in the matrix of the nitrogen-doped porous carbon. The obtained hydrogen evolution catalyst uses nitrogen-doped porous carbon as a carrier, with uniformly distributed nano-MoP inside, having excellent catalytic activity. The specific surface area of the porous carbon is large, containing a large number of porous structures, and having excellent conductivity after nitrogen doping, with more active sites for electrochemical reactions and better catalytic performance, which is beneficial to the electron transfer during the electrolytic water hydrogen evolution reaction process, thereby reducing the hydrogen evolution overpotential and having excellent hydrogen evolution activity.

[0043] In Comparative Example 1, the carbonization product of the mixture of polypyrrole and ammonium molybdate was used as the hydrogen evolution catalyst. Polypyrrole does not contain phosphorus elements and cannot generate catalytically active nano-MoP with Mo ions. As a result, the hydrogen evolution overpotential of the catalyst is relatively high, reaching 260.9 mV, and the hydrogen evolution activity is poor.

[0044] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a hydrogen evolution catalyst, characterized in that, The preparation method is as follows: Step (1): Under an ice bath, add pyrrole and spiro pentaerythritol bisphosphoryl dipyrrole to a methanol solution of ferric chloride. After the reaction, distill the solution under reduced pressure, wash and dry it to obtain a spiro pentaerythritol bisphosphoryl dipyrrole cross-linked copolymer; Step (2): Add the spiro pentaerythritol bisphosphoryl dipyrrole cross-linked copolymer to an ethanol solution containing ammonium molybdate. After mixing, perform ultrasonic treatment for 30 - 60 min. After filtration, place the mixture in a tubular furnace. Under a nitrogen atmosphere, control the heating rate at 3 - 6 °C / min, heat to 700 - 850 °C, keep the temperature for 2 - 3 h, and then cool to obtain a hydrogen evolution catalyst.

2. The preparation method of the hydrogen evolution catalyst according to claim 1, wherein, In the step (1), the mass concentration of the methanol solution of ferric chloride is 20 - 30 g / L.

3. The preparation method of the hydrogen evolution catalyst according to claim 1, characterized in that, In the step (1), the mass of spiro pentaerythritol bisphosphoryl dipyrrole is 35 - 80% of the mass of pyrrole.

4. The preparation method of the hydrogen evolution catalyst according to claim 1, wherein, In the step (1), the reaction is first stirred under an ice bath for 18 - 24 h, and then reacted at room temperature for 6 - 8 h.

5. The preparation method of the hydrogen evolution catalyst according to claim 1, characterized in that, In the step (2), the mass concentration of the ethanol solution of ammonium molybdate is 10 - 25 g / L.

6. The preparation method of the hydrogen evolution catalyst according to claim 1, characterized in that, The preparation method of the spiro pentaerythritol bisphosphoryl dipyrrole is as follows: Add pyrrole, spiro pentaerythritol bisphosphoryl dichloride, and a catalyst triethylamine to a solvent. After the reaction, distill the solution under reduced pressure, and recrystallize the product to obtain spiro pentaerythritol bisphosphoryl dipyrrole.

7. The preparation method of the hydrogen evolution catalyst according to claim 6, characterized in that, In the preparation method of the spiro pentaerythritol bisphosphoryl dipyrrole, the solvent is any one of dichloromethane, acetonitrile, and 1,4 - dioxane.

8. The preparation method of the hydrogen evolution catalyst according to claim 6, wherein, The mass of the pyrrole is 45 - 53% of the mass of spiro pentaerythritol bisphosphoryl dichloride.

9. The preparation method of the hydrogen evolution catalyst according to claim 6, wherein, In the preparation method of the spiro pentaerythritol bisphosphoryl dipyrrole, the reaction is first carried out under an ice bath for 20 - 30 min, and then carried out at 30 - 55 °C for 6 - 10 h.

10. Application of a hydrogen evolution catalyst obtained by the preparation method according to any one of claims 1 - 9 in hydrogen production by electrolyzing water.

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