Hydrogen evolution electrode catalyst, method for preparing the same, and method for preparing hydrogen

Abstract

This invention relates to the field of hydrogen production technology through water electrolysis, and discloses a hydrogen evolution electrode catalyst, its preparation method, and a method for producing hydrogen gas. The hydrogen evolution electrode catalyst provided by this invention has a unique dendritic structure and exhibits excellent hydrogen evolution ability. This catalyst uses Ni and Ag as the main raw materials, significantly reducing the cost of catalysts for hydrogen production through water electrolysis. Furthermore, due to the simple preparation method, readily available raw materials, and low equipment requirements, this catalyst has the potential for large-scale application.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis for hydrogen production technology, specifically to a hydrogen evolution electrode catalyst, its preparation method, and a method for producing hydrogen gas. Background Technology

[0002] Hydrogen energy boasts advantages such as high energy density, being green and pollution-free, diverse sources, abundant reserves, and wide applications. Furthermore, it can be combined with other energy sources like wind, electricity, and solar power. Therefore, hydrogen energy has stood out among numerous energy sources, becoming a focal point of attention on the 21st-century global energy stage. Currently, hydrogen production technology still primarily relies on fossil fuels, but this inherently presents carbon emission problems. Against the backdrop of "dual carbon targets" and energy transition, developing clean water electrolysis hydrogen production technology will be crucial for achieving "carbon neutrality."

[0003] Due to the kinetic limitations of the hydrogen evolution reaction (HER), noble metal catalysts are currently recognized as the most effective catalysts for water electrolysis. However, the high cost and low reserves of noble metals make it difficult to support large-scale production applications. Therefore, finding low-cost, high-performance HER catalysts is one of the key factors driving the promotion of hydrogen energy. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of high cost and limited availability of precious metal catalysts in water electrolysis for hydrogen production, which hinder large-scale application. This invention provides a hydrogen evolution electrode catalyst, its preparation method, and a method for producing hydrogen. The hydrogen evolution electrode catalyst provided by this invention uses Ni and Ag as main raw materials, significantly reducing costs compared to existing precious metal catalysts. Furthermore, this catalyst exhibits excellent electrocatalytic hydrogen evolution performance, making it suitable for industrial-scale production applications.

[0005] To achieve the above objectives, the present invention provides a hydrogen evolution electrode catalyst, the catalyst comprising a support and Ag supported on the support, the support comprising NiO.

[0006] A second aspect of the present invention provides a method for preparing a hydrogen evolution electrode catalyst, the method comprising: contacting a support material made of elemental Ni with a reaction solution containing an oxidant and a silver salt, such that Ag is loaded onto the support during the formation of NiO.

[0007] A third aspect of the present invention provides a hydrogen evolution electrode catalyst prepared according to the method described in the second aspect.

[0008] A fourth aspect of the present invention provides a method for preparing hydrogen, the method comprising contacting the hydrogen evolution electrode catalyst described in the first or third aspect with an electrolyte and reacting under electrolysis conditions.

[0009] Through the above technical solution, the present invention can achieve at least the following beneficial effects:

[0010] (1) The hydrogen evolution electrode catalyst provided by this invention has a special dendritic structure and exhibits excellent hydrogen evolution performance. Experiments have shown that when the Ag loading on NiO / Ni is 0.45 wt% per square centimeter, the catalyst achieves a hydrogen evolution performance of 10 mA·cm⁻¹. -2 The HER overpotential at current density is only 216mV.

[0011] (2) The hydrogen evolution electrode catalyst provided by the present invention uses Ag to replace the precious metals such as Pt in the traditional hydrogen evolution catalyst, which greatly reduces the cost. Moreover, since the reserves of Ag are much higher than those of other precious metals, it is possible to use this catalyst for industrial-scale hydrogen production.

[0012] (2) The preparation method of the hydrogen evolution electrode catalyst provided by the present invention is simple, the conditions are mild, the raw materials are readily available, and the equipment requirements are low, making it suitable for large-scale production. Attached Figure Description

[0013] Figure 1 This is a SEM image of the hydrogen evolution electrode catalyst A1 obtained in Example 1.

[0014] Figure 2 This is the LSV curve of the hydrogen evolution electrode catalyst A1 obtained in Example 1.

[0015] Figure 3 This is a SEM image of the hydrogen evolution electrode catalyst A8 obtained in Example 8. Detailed Implementation

[0016] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0017] The inventors of this invention accidentally discovered during their research that by loading Ag onto a NiO-containing material, a composite material with good hydrogen production capacity through water electrolysis could be obtained. This material uses relatively inexpensive Ag to replace precious metals such as Pt in traditional hydrogen evolution catalysts, effectively reducing the cost of hydrogen production through water electrolysis and providing the possibility for industrial-scale hydrogen production.

[0018] Based on the above findings, the first aspect of the present invention provides a hydrogen evolution electrode catalyst, the catalyst comprising a support and Ag supported on the support, the support comprising NiO.

[0019] According to a preferred embodiment of the present invention, the carrier further includes Ni.

[0020] According to some preferred embodiments of the present invention, the carrier is a composite material composed of Ni and NiO (which may be simply referred to as "Ni / NiO composite material", "Ni / NiO material" or "Ni / NiO" in this invention).

[0021] Preferably, the weight ratio of Ni to NiO in the carrier is 20-70:1, more preferably 25-50:1.

[0022] The inventors of this invention also discovered in their research that the hydrogen evolution electrode catalyst prepared when the Ni / NiO composite material used as the support has a certain thickness has better hydrogen evolution ability.

[0023] According to some preferred embodiments of the present invention, the thickness of the carrier is 0.5-2 mm, preferably 0.5-1 mm.

[0024] To further improve the hydrogen evolution performance of the hydrogen evolution electrode catalyst, a support with a specific pore structure can be selected. According to some preferred embodiments of the present invention, the pore size of the support is 0.01-0.6 mm, and the porosity is 70-90%.

[0025] Preferably, the average pore size of the carrier is 0.1-0.5 mm.

[0026] In this invention, there is no particular limitation on the loading amount of Ag in the hydrogen evolution electrode catalyst, as long as it can achieve a satisfactory hydrogen evolution effect.

[0027] According to some preferred embodiments of the present invention, the loading of Ag in the catalyst is 0.1-1.5 wt%, preferably 0.13-1.25 wt%, based on the total weight of the catalyst.

[0028] Preferably, the catalyst has a dendritic structure. The dendritic structure refers to a catalyst morphology exhibiting a "trunk" and "lateral branches" forming on the sides of the "trunk" (see reference for details). Figure 1 As can be seen from the figure, the lateral branches are symmetrically and orderly arranged, growing closely on both sides of the main trunk (with uniform dendrite size), which can usually be observed by scanning electron microscopy. Preferably, in the "dendritic structure" of the catalyst provided by the present invention, the main trunk is 5-15 μm long and 0.5-3 μm in diameter, and the lateral branches (with rod-like morphology) are 1-5 μm long and 0.3-2.5 μm in diameter.

[0029] Preferably, based on elemental composition, the weight ratio of Ag to Ni provided by NiO in the catalyst is 1:3-17, more preferably 1:5-12.

[0030] This invention does not impose any particular limitation on the specific preparation method of the provided hydrogen evolution electrode catalyst; existing methods for preparing supported catalysts can be used. However, the inventors of this invention ingeniously discovered during their research that, compared to the traditional impregnation method for loading silver onto Ni / NiO materials, the hydrogen evolution electrode catalyst prepared by introducing silver during the oxidation of elemental nickel (for example, by contacting it with silver-containing compounds during nickel oxidation) exhibits a tighter bond between Ag and the support, thus resulting in a longer stable service life.

[0031] Based on the above findings, a second aspect of the present invention provides a method for preparing a hydrogen evolution electrode catalyst, the method comprising: contacting a support material made of elemental Ni with a reaction solution containing an oxidant and a silver source, such that Ag is loaded onto the support during the formation of NiO.

[0032] In this invention, there are no particular restrictions on the specific form (such as shape, size, etc.) of the carrier material, as long as it is elemental nickel. For example, Ni materials in common forms such as sheet or plate, block or granule, filament, mesh, or powder can be used as carrier materials, or special metal materials of Ni such as nickel foam can be used.

[0033] According to some preferred embodiments of the present invention, the carrier material is selected from nickel foam.

[0034] Preferably, the thickness of the nickel foam is 0.5-2 mm, and more preferably 0.5-1 mm.

[0035] Preferably, the nickel foam has a pore size of 0.01-0.6 mm and a porosity of 70-90%.

[0036] Preferably, the average pore size of the nickel foam is 0.1-0.5 mm.

[0037] In this invention, the oxidant refers to a compound that can oxidize Ni in a carrier raw material to form NiO. According to some preferred embodiments of the invention, the oxidant is selected from at least one of persulfate, persulfate, and hydrogen peroxide.

[0038] Preferably, the oxidant is selected from at least one of persulfate or persulfate, and more preferably from at least one of ammonium persulfate, sodium persulfate and potassium persulfate.

[0039] In this invention, the silver source refers to a compound that provides Ag for loading onto Ni during the oxidation process. This invention does not impose any particular limitation on the specific amount of silver source used, as long as a catalyst with satisfactory hydrogen evolution performance can be obtained. According to some preferred embodiments of the invention, the silver salt content in the reaction solution is such that the Ag loading in the prepared catalyst, based on the total weight of the catalyst, is 0.1-1.5% by weight, preferably 0.13-1.25% by weight.

[0040] Preferably, the weight ratio of the silver source to the oxidant in the reaction solution is 1:10-50.

[0041] Preferably, the silver source is selected from water-soluble compounds of Ag, and more preferably silver nitrate.

[0042] According to a preferred embodiment of the present invention, the contact method includes placing the support material in the reaction solution and allowing it to stand for 10-30 hours. To ensure a more uniform Ag distribution on the prepared catalyst, it is preferable that the support material is completely immersed in the reaction solution.

[0043] According to a preferred embodiment of the present invention, the method further includes a step of first cleaning the carrier material before it comes into contact with the reaction solution. The purpose of the first cleaning is to remove grease, dust and other deposits from the surface of the carrier material.

[0044] Any cleaning method capable of achieving the above objectives is applicable to this invention. Preferably, the first cleaning method includes sequentially cleaning the carrier material with an organic solvent and an inorganic acid.

[0045] Preferably, the organic solvent is selected from at least one of organic solvents with no more than 5 carbon atoms (e.g., ethanol, acetone, etc.).

[0046] Preferably, the inorganic acid is an aqueous solution selected from at least one of sulfuric acid, hydrochloric acid, and nitric acid, and preferably contains H+. + The concentration should not exceed 3M, preferably 0.5-2M.

[0047] Preferably, the first cleaning is performed by ultrasonic cleaning. Preferably, ultrasonic cleaning is performed in organic solvents and inorganic acids for 5-60 minutes each, more preferably 10-40 minutes.

[0048] According to a preferred embodiment of the present invention, the method further includes a second cleaning and drying step of the reacted carrier material after contact (completion). The purpose of the second cleaning is to remove the reaction liquid from the surface of the material, preferably by rinsing with water or an organic solvent.

[0049] Preferably, the drying conditions include: a temperature of 20-60°C and a drying time of 4-12 hours.

[0050] A third aspect of the present invention provides a hydrogen evolution electrode catalyst prepared according to the method described in the second aspect. The characteristics of this catalyst are as previously described and will not be repeated here.

[0051] A fourth aspect of the present invention provides a method for preparing hydrogen, the method comprising contacting the hydrogen evolution electrode catalyst described in the first or third aspect with an electrolyte and reacting under electrolysis conditions.

[0052] The present invention will be described in detail below through embodiments. It should be understood that the following embodiments are only used to further explain and illustrate the content of the present invention by way of example, and are not intended to limit the present invention.

[0053] Unless otherwise specified, all reagents used in the following examples are commercially available products purchased from legitimate chemical suppliers and are of analytical purity.

[0054] In the following embodiments, unless otherwise specified, the thickness of the nickel foam used is 0.5 mm, the pore size is 0.01-0.6 mm (average pore size is about 0.4 mm), and the porosity is about 80%.

[0055] Unless otherwise specified, the operating temperature in the following embodiments is room temperature (25±5℃).

[0056] Example 1

[0057] The hydrogen evolution electrode catalyst was prepared using the following method:

[0058] (1) Take a 2cm×2cm piece of nickel foam, first immerse it in ethanol and ultrasonically clean it for 30 minutes, then take it out and immerse it in 1M sulfuric acid solution and ultrasonically clean it for 10 minutes to obtain clean nickel foam.

[0059] (2) Prepare 30 mL of ammonium persulfate solution (containing 0.44 g of ammonium persulfate) and add 0.018 g of silver nitrate to it. After dissolving, mix well to obtain the reaction solution.

[0060] (3) The clean nickel foam was completely immersed in the reaction solution and allowed to stand for 10 hours. After the reaction was completed, the nickel foam was removed, washed with deionized water, and dried at 40°C for 10 hours. Hydrogen evolution electrode catalyst A1 was obtained.

[0061] Example 2

[0062] The method described in Example 1 was used, except that the reaction solution was prepared as follows: 0.008 g of silver nitrate was added to 50 mL of ammonium persulfate solution (containing 0.3 g of ammonium persulfate), dissolved, and mixed thoroughly. All other operations and conditions were the same as in Example 1, resulting in hydrogen evolution electrode catalyst A2.

[0063] Example 3

[0064] The method described in Example 1 was used, except that the reaction solution was prepared as follows: 0.032 g of silver nitrate was added to 80 mL of ammonium persulfate solution (containing 0.9 g of ammonium persulfate), dissolved, and mixed thoroughly. All other operations and conditions were the same as in Example 1, resulting in hydrogen evolution electrode catalyst A3.

[0065] Example 4

[0066] The method described in Example 1 was used, except that the reaction solution was prepared as follows: 0.045 g of silver nitrate was added to 60 mL of ammonium persulfate solution (containing 0.6 g of ammonium persulfate), dissolved, and mixed thoroughly. All other operations and conditions were the same as in Example 1, resulting in hydrogen evolution electrode catalyst A4.

[0067] Example 5

[0068] The method in Example 1 was used, except that a 1 mm thick nickel foam (with the same pore size) was used as the support material. All other operations and conditions were the same as in Example 1 to obtain hydrogen evolution electrode catalyst A5.

[0069] Example 6

[0070] The method in Example 1 was used, except that a nickel foam with a thickness of 0.8 mm (with the same pore size) was used as the support material. All other operations and conditions were the same as in Example 1 to obtain hydrogen evolution electrode catalyst A6.

[0071] Example 7

[0072] The method in Example 1 was used, except that a 1.6 mm thick nickel foam (with the same pore size) was used as the support material. All other operations and conditions were the same as in Example 1 to obtain hydrogen evolution electrode catalyst A7.

[0073] Example 8

[0074] The method described in Example 1 was used, except that the silver nitrate in the reaction solution was replaced with 0.001 g of Ag particles (average particle size of approximately 0.2 μm). All other operations and conditions were the same as in Example 1, and hydrogen evolution electrode catalyst A8 was obtained.

[0075] Example 9

[0076] The method described in Example 1 was used, except that silver nitrate was not added to the reaction solution. Instead, after the nickel foam was prepared into a Ni / NiO material (i.e., a support) using the reaction solution, 0.001 g of Ag particles (with an average particle size of approximately 0.2 μm) were loaded onto the Ni / NiO material using an impregnation method. All other operations and conditions were the same as in Example 1, resulting in hydrogen evolution electrode catalyst A9.

[0077] Test Example 1

[0078] Scanning electron microscopy was used to observe the catalysts obtained in the above examples, and it was found that catalysts A1-A7 have a unique dendritic structure. Figure 1 The SEM image of A1 is shown as an example, and the SEM images of A2-A7 are similar. Catalysts A8 and A9, however, do not have such a dendritic structure; the Ag particles are directly supported on the surface of the Ni / NiO material. Figure 3 The SEM image of catalyst A8 is shown; the SEM image of A9 has similar characteristics.

[0079] The contents of Ni and NiO, as well as the loading of Ag, in the catalysts obtained in the above examples were detected by X-ray photoelectron spectroscopy (XPS). The weight ratio of Ni to NiO in the support of each catalyst and the weight ratio of Ag to Ni provided by NiO in the catalyst were calculated. The results are detailed in Table 1.

[0080] Table 1

[0081] catalyst Ni to NiO weight ratio Ag loading (wt.%) The weight ratio of Ag to Ni provided by NiO A1 30 0.45 1:7.7 A2 45 0.2 1:11 A3 22 0.8 1:5.5 A4 32 1.02 1:3.1 A5 58 0.21 1:8.2 A6 47 0.30 1:7.1 A7 64 0.14 1:11.4 A8 34 0.8 1:3.7 A9 41 0.5 1:4.9

[0082] Test Example 2

[0083] The catalyst prepared in the above examples was used as the working electrode to test its HER performance.

[0084] The specific method is as follows:

[0085] Electrochemical testing was conducted using a Shanghai Chenhua 760E electrochemical workstation. Before testing, N2 was passed through the electrolyte for approximately 30 minutes to saturate it. Then, the three-electrode testing system was assembled, with the voltage range set to -0.1 to 0.1 V (vs. RHE) and the number of test cycles set to 20 to ensure complete sample activation and exposure of active sites. Next, H2 was passed through the electrolyte using a hydrogen generator for 30 minutes to completely saturate it. LSV testing was then performed at 0 to -0.6 V. 1M KOH was used as the electrolyte at 10 mA·cm⁻¹. -2 The HER overpotential of the catalyst was measured at the specified current density. With the electrolysis conditions unchanged, the HER overpotential of the catalyst was measured again after the working electrode had been operating continuously for 12 hours. The results are detailed in Table 2. Figure 2 An exemplary LSV plot (0h) of catalyst A1 is shown for reference.

[0086] Table 2

[0087]

[0088] Note: Catalysts A8 and A9 are difficult to operate continuously for a long time. After about 10 hours, their hydrogen evolution capacity has decreased by more than 10%. Therefore, their overpotential was not tested after 12 hours of continuous operation.

[0089] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An electrolytic water hydrogen evolution electrode catalyst, characterized by, The catalyst includes a support and Ag supported on the support, wherein the support is a composite material composed of Ni and NiO; the weight ratio of Ni to NiO in the support is 20-70:1; and the weight ratio of Ag to Ni provided by NiO in the catalyst is 1:3-17 (elementally). The preparation method of the hydrogen evolution electrode catalyst includes: contacting a support material made of elemental Ni with a reaction solution containing an oxidant and a silver source, so that Ag is loaded on the support during the formation of NiO; the silver source is selected from a water-soluble compound of Ag.

2. The hydrogen evolution electrode catalyst of claim 1, wherein, In the carrier, the weight ratio of Ni to NiO is 25-50:

1.

3. The hydrogen evolution electrode catalyst of claim 1, wherein, The thickness of the carrier is 0.5-2 mm; And / or, the carrier has a pore size of 0.01-0.6 mm and a porosity of 70-90%.

4. The hydrogen evolution electrode catalyst of claim 3, wherein, The thickness of the carrier is 0.5-1mm.

5. The hydrogen evolution electrode catalyst of claim 1, wherein, In the catalyst, the loading of Ag is 0.1-1.5% by weight, based on the total weight of the catalyst.

6. The hydrogen evolution electrode catalyst of claim 5, wherein, In the catalyst, the loading of Ag is 0.13-1.25% by weight, based on the total weight of the catalyst.

7. The hydrogen evolution electrode catalyst of claim 1, wherein, The catalyst has a dendritic structure with a dendritic trunk length of 5-15 μm and a diameter of 0.5-3 μm, and lateral branches length of 1-5 μm and a diameter of 0.3-2.5 μm.

8. The hydrogen evolution electrode catalyst of claim 1, wherein, In terms of elements, the weight ratio of Ag to Ni provided by NiO in the catalyst is 1:5-12.

9. The hydrogen evolution electrode catalyst of claim 1, wherein, The carrier material is selected from nickel foam.

10. The hydrogen evolution electrode catalyst of claim 9, wherein, The thickness of the nickel foam is 0.5-2 mm.

11. The hydrogen evolution electrode catalyst of claim 10, wherein, The thickness of the nickel foam is 0.5-1 mm.

12. The hydrogen evolution electrode catalyst of claim 11, wherein, The nickel foam has a pore size of 0.01-0.6 mm and a porosity of 70-90%.

13. The hydrogen evolution electrode catalyst according to claim 1, wherein, The oxidant is selected from at least one of persulfate, persulfate and hydrogen peroxide.

14. The hydrogen evolution electrode catalyst according to claim 13, wherein, The oxidant is selected from at least one of persulfate or persulfate.

15. The hydrogen evolution electrode catalyst according to claim 14, wherein, The oxidant is at least one of ammonium persulfate, sodium persulfate, and potassium persulfate.

16. The hydrogen evolution electrode catalyst according to claim 1, wherein, In the reaction solution, the weight ratio of silver source to oxidant is 1:10-50.

17. The hydrogen evolution electrode catalyst according to claim 1, wherein, The silver source is silver nitrate.

18. The hydrogen evolution electrode catalyst according to any one of claims 9-17, wherein, The contact method includes placing the carrier raw material into the reaction solution and letting it stand for 10-30 hours.

19. The hydrogen evolution electrode catalyst according to claim 18, wherein, The carrier material is completely immersed in the reaction solution.

20. A method for preparing hydrogen, characterized in that, The method includes contacting the hydrogen evolution electrode catalyst according to any one of claims 1-19 with an electrolyte and reacting it under electrolysis conditions.

Images