Water electrolysis hydrogen evolution catalyst and preparation method thereof and method for producing hydrogen by water electrolysis

Abstract

This invention relates to the field of alkaline water electrolysis for hydrogen production, and discloses a water electrolysis hydrogen evolution catalyst, its preparation method, and a method for water electrolysis to produce hydrogen. The catalyst contains Ru, Co, Ni, C, and N; wherein C exists in the catalyst in the form of carbon nanotubes; the Ru content in the catalyst is 0.1-5 wt%, and the average particle size of Ru is 2-5 nm. This invention uses a carbon nanotube composite structure generated by ZIF pyrolysis as a support, which improves the charge transfer capacity by increasing the Ru loading and dispersion. Furthermore, the synergistic effect of Ru with Co and Ni effectively enhances the catalytic hydrogen evolution activity of the Ru-Co-Ni water electrolysis hydrogen evolution catalyst.

Description

Technical Field

[0001] This invention relates to the field of hydrogen production through water electrolysis in alkaline systems, specifically to a hydrogen evolution catalyst for water electrolysis, its preparation method, and a method for hydrogen production through water electrolysis. Background Technology

[0002] Hydrogen energy possesses both energy and material properties, making its development beneficial for establishing a mature and safe modern energy system. Currently, commercially available hydrogen evolution catalysts for water electrolysis are mainly platinum-based precious metal catalysts, but these catalysts are expensive. Therefore, exploring efficient non-precious metal and low-precious metal hydrogen evolution catalysts to reduce the cost of water electrolysis is essential.

[0003] Currently, numerous transition metals are being developed for constructing hydrogen evolution electrode materials. However, many of these catalysts suffer from complex preparation processes or insufficient activity. Therefore, to improve catalyst performance, a small amount of noble metal loading is often required. Consequently, reducing the noble metal loading while ensuring improved activity is crucial. Some studies have employed high-temperature plasma spraying or electroplating methods to alloy the noble metal onto porous nickel mesh substrates to improve catalyst activity and reduce noble metal loading. However, this method results in high noble metal loading and leads to precious metal waste during the spraying process.

[0004] Therefore, there is an urgent need for a catalyst with low noble metal loading but high hydrogen evolution catalytic activity and its preparation process. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of high precious metal loading and precious metal waste in the existing technology, and to provide an electrolytic water hydrogen evolution catalyst, its preparation method and a method for producing hydrogen by electrolytic water. The electrolytic water hydrogen evolution catalyst is loaded with a small amount of precious metal Ru and has high hydrogen evolution catalytic activity.

[0006] To achieve the above objectives, the first aspect of the present invention provides a catalyst for hydrogen evolution through water electrolysis, wherein the catalyst contains Ru, Co, Ni, C and N; wherein C exists in the catalyst in the form of carbon nanotubes; the content of Ru in the catalyst is 0.1-5 wt%, and the average particle size of Ru is 2-5 nm.

[0007] A second aspect of the present invention provides a method for preparing a hydrogen evolution catalyst for water electrolysis, wherein the preparation method includes the following steps:

[0008] S1. In the presence of the first solvent, the Co source, Ni source and nitrogen-containing organic ligand are mixed and reacted to obtain the precursor.

[0009] S2. The precursor is heated in the presence of a protective gas; the heating temperature is greater than or equal to 700°C.

[0010] S3. In the presence of the second solvent, the product obtained in S2 and the Ru source are mixed for the second time. Then, the mixture after the second mixing is mixed with the reducing agent for the third time and an in-situ reduction reaction is carried out.

[0011] A third aspect of the present invention provides a hydrogen evolution catalyst for water electrolysis prepared by the preparation method provided by the present invention.

[0012] A fourth aspect of the present invention provides a method for producing hydrogen by electrolysis of water, wherein the method includes: passing electricity through an electrolyte in the presence of a hydrogen evolution catalyst in water electrolysis to produce hydrogen gas; wherein the hydrogen evolution catalyst in water electrolysis is the hydrogen evolution catalyst in water electrolysis provided by the present invention.

[0013] The beneficial effects of the present invention through the above technical solution include at least the following:

[0014] Zeolite-like imidazole frameworks (ZIFs) offer numerous advantages, such as high porosity and large specific surface area. Three-dimensional ZIF catalyst precursors, prepared using Co and Ni metal nodes and nitrogen-containing organic ligands (such as methylimidazolium) as linkers, form abundant M-Nx active sites after high-temperature pyrolysis. These active sites can also serve as active centers for electrocatalytic reactions. The porous carbon nanotube structure enhances charge transfer capabilities, exhibiting high specific surface area and numerous defect sites. The abundant pyridine nitrogen is beneficial for coordination and adsorption with Ru, which can reduce the Ru loading particle size and improve its catalytic activity.

[0015] Co-based and Ni-based catalysts exhibit good intrinsic catalytic hydrogen evolution activity. This invention efficiently synthesizes a Co-Ni bimetallic zeolite imidazole framework material. Under the catalysis of Co and Ni, high-temperature pyrolysis yields a porous carbon-based composite structure of carbon nanotubes with high graphitization and high dispersion of N and active materials. This improves both conductivity and the intrinsic activity of the Co-Ni metal. In a preferred embodiment, through the adsorption of Ru ions at carbon defect sites in an N-methylpyrrolidone weakly alkaline solution, combined with an in-situ hydrogen reduction process, a small amount of noble metal Ru is highly dispersed at the nanoscale on the carbon-based support, resulting in a synergistic effect between Ru and CoNi. The catalyst of this invention exhibits excellent electrocatalytic hydrogen evolution performance. Attached Figure Description

[0016] Figure 1 This is a transmission electron microscope image of the Ru-Co-Ni electrolytic hydrogen evolution catalyst prepared in Example 1 of this invention;

[0017] Figure 2This is a high-resolution transmission electron microscope image of the Ru-Co-Ni electrolytic hydrogen evolution catalyst prepared in Example 1 of this invention;

[0018] Figure 3 This is the X-ray photoelectron spectrum of the nitrogen element in the Ru-Co-Ni electrolytic hydrogen evolution catalyst prepared in Example 1 of this invention;

[0019] Figure 4 This is a transmission electron microscope image of the Ru-Co-Ni electrolytic hydrogen evolution catalyst prepared in Example 2 of this invention;

[0020] Figure 5 This is a high-resolution transmission electron microscope image of the Ru-Co-Ni electrolytic hydrogen evolution catalyst prepared in Example 2 of this invention;

[0021] Figure 6 This is the AC impedance diagram of the Ru-Co-Ni water electrolysis hydrogen evolution catalyst prepared in Example 1 and Comparative Example 1 of this invention in a three-electrode test system. Detailed Implementation

[0022] 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.

[0023] The first aspect of the present invention provides a catalyst for hydrogen evolution in water electrolysis, wherein the catalyst contains Ru, Co, Ni, C and N; wherein C exists in the catalyst in the form of carbon nanotubes; the content of Ru in the catalyst is 0.1-5 wt%, and the average particle size of Ru is 2-5 nm.

[0024] The hydrogen evolution catalyst for water electrolysis of this invention has a low Ru content, with a small amount of noble metal Ru highly dispersed at the nanoscale on a carbon-based support. Transition metals Co and Ni inherently possess good hydrogen evolution catalytic activity, and the synergistic effect between the multiple metals allows for electron transfer, further enhancing the intrinsic activity of the catalyst. The synergistic effect of Ru with Co and Ni results in an excellent electrocatalytic hydrogen evolution performance.

[0025] According to the present invention, preferably, the Co content in the catalyst is 22-50 wt%;

[0026] And / or, the Ni content in the catalyst is 1-10 wt%.

[0027] When the contents of Ru, Co, and Ni meet the aforementioned ranges, the synergistic effect between the metals can be further enhanced, thereby further improving the intrinsic activity of the catalyst.

[0028] Furthermore, the molar ratio of Co to Ni in the catalyst is 1:(0.07-0.2).

[0029] According to the present invention, preferably, the C content in the catalyst is 49-75 wt%;

[0030] And / or, the N content in the catalyst is 1-5 wt%.

[0031] A second aspect of the present invention provides a method for preparing a hydrogen evolution catalyst for water electrolysis, wherein the preparation method includes the following steps:

[0032] S1. In the presence of the first solvent, the Co source, Ni source and nitrogen-containing organic ligand are mixed and reacted to obtain the precursor.

[0033] S2. The precursor is heated in the presence of a protective gas; the heating temperature is greater than or equal to 700°C.

[0034] S3. In the presence of the second solvent, the product obtained in S2 and the Ru source are mixed for the second time. Then, the mixture after the second mixing is mixed with the reducing agent for the third time and an in-situ reduction reaction is carried out.

[0035] This invention uses Co and Ni atoms as metal nodes to coordinate with nitrogen-containing organic ligands to prepare a CoNi bimetallic ZIF material. This material is then heated (high-temperature annealing) in the presence of a protective gas to obtain an N-doped porous carbon nanotube composite CoNi bimetallic structure. Furthermore, the abundant pyridine nitrogen on the carbon nanotube surface is used for coordination adsorption with Ru, followed by further reduction to finally prepare a hydrogen evolution catalyst suitable for alkaline water electrolysis systems. This hydrogen evolution catalyst is a Ru-Co-Ni ternary metal composite carbon nanotube structure, where the pyridine nitrogen on the carbon nanotube surface forms numerous M-Nx active sites with the metal.

[0036] According to the present invention, preferably, in S1, the Co source, the Ni source and the nitrogen-containing organic ligand are mixed in the first mixture at a weight ratio of (3.5-5.5):1:(4-10).

[0037] According to the present invention, preferably, the temperature of the first reaction is 20-30°C and the time is 20-30h.

[0038] The present invention does not impose any particular limitation on the amount of the first solvent. In order to better mix the Co source, Ni source and nitrogen-containing organic ligand so that the reaction can proceed smoothly, preferably, the amount of the first solvent is 20-40 mL based on the total weight of the Co source, the Ni source and the nitrogen-containing organic ligand.

[0039] According to the present invention, preferably, the Co source is selected from water-soluble cobalt salts, and more preferably cobalt nitrate.

[0040] According to the present invention, preferably, the Ni source is selected from water-soluble nickel salts, and more preferably nickel nitrate.

[0041] According to the present invention, preferably, the nitrogen-containing organic ligand is 2-methylimidazole.

[0042] According to the present invention, preferably, the first solvent is selected from C1-C4 monohydric alcohols, and more preferably methanol.

[0043] To obtain a pure CoNi bimetallic ZIF precursor material, in step S1, after the initial reaction of the Co source, Ni source, and nitrogen-containing organic ligand, solid-liquid separation, washing, and drying are performed. Solid-liquid separation can be performed using conventional methods in the art, such as centrifugation. Washing is performed using a solvent that does not damage the morphology and structure of the precursor material and is easily volatile, such as anhydrous ethanol. Drying can be carried out at 55-65°C using vacuum drying for 1-3 hours.

[0044] In S2, the protective gas is selected from nitrogen and / or an inert gas, preferably from at least one of argon, helium, and neon. Argon is more preferred.

[0045] According to the present invention, preferably, in S2, the heating conditions include: heating to 700-900°C at a rate of 4-7°C / min, and maintaining the temperature at 700-900°C for 1.5-2.5 hours. If the heating temperature is below 700°C, carbon nanotube structures cannot be formed; if the heating temperature is above 1000°C, the catalyst will sinter, thereby affecting the hydrogen evolution activity of the catalyst.

[0046] After heating (high-temperature pyrolysis), CoNi bimetallic ZIF materials can form abundant M-Nx active sites. These active sites can also serve as active centers for electrocatalytic reactions. The porous carbon nanotubes formed enhance charge transfer capabilities and have high specific surface area and defect sites. The abundant pyridine nitrogen is beneficial for coordination and adsorption with Ru, which can reduce the Ru loading particle size and improve its catalytic activity.

[0047] According to the present invention, preferably, in S3, the product obtained in S2 and the Ru source are mixed in the second mixture at a weight ratio of (8-12):1.

[0048] Through the second mixing, the product obtained in S2 utilizes the abundant pyridine nitrogen on its carbon nanotube surface to coordinate and adsorb with the Ru source. To further improve the efficiency of coordination adsorption, the conditions for the second mixing preferably include: a temperature of 55-65°C and a time of 10-15 h.

[0049] To better disperse the Ru source and fully mix it with the product obtained from S2 (CoNi-N doped carbon nanotube composite material), thereby making the Ru source more uniform and fully adsorbed, the product obtained from S2 and the Ru source were dissolved in a second solvent, ultrasonically dispersed for 0.5-3 hours, and then maintained at a temperature of 55-65℃ for 10-15 hours with stirring.

[0050] According to the present invention, preferably, the Ru source is selected from water-soluble Ru salts, and more preferably RuCl3.

[0051] According to the present invention, preferably, the second solvent is selected from a weakly basic organic solvent, in which the carrier defect sites can effectively adsorb Ru ions. More preferably, the second solvent is N-methylpyrrolidone (NMP).

[0052] According to the present invention, preferably, the amount of the second solvent is 115-125 mL, based on the total weight of the product obtained in S2 and the Ru source being 1 g.

[0053] The present invention does not have any particular limitation on the type of reducing agent, as long as it can reduce Ru ions in situ. Preferably, the reducing agent is NaHB4.

[0054] The method of adding the reducing agent is not particularly limited in this invention. To ensure better mixing of the reducing agent with the material adsorbing Ru ions and to allow the in-situ reduction reaction to proceed fully, the reducing agent can be dissolved in a solvent first, such as NMP, and then the solution containing the reducing agent can be added to the feed solution containing the material adsorbing Ru ions. The amount of reducing agent used in this invention does not include the amount of solvent used to dissolve the reducing agent.

[0055] According to the present invention, preferably, the amount of reducing agent is 5-7g, based on 1g of the weight of the Ru source.

[0056] According to the present invention, preferably, the temperature of the in-situ reduction reaction is 20-30°C and the time is 0.5-1.5h.

[0057] To facilitate catalyst separation, preferably, a carbonyl compound, such as acetone, is added after the in-situ reduction reaction. According to a specific embodiment of the present invention, based on 1 g of the reducing agent, the amount of acetone used is 40-60 mL.

[0058] To obtain a pure and dry product, in step S3, after the in-situ reduction reaction, the reaction product undergoes solid-liquid separation, washing, and drying. Solid-liquid separation can be performed using conventional methods in the art, such as centrifugation. Washing is performed using a solvent that does not damage the morphology and structure of the precursor material and is easily volatile, such as anhydrous ethanol. Drying can be carried out at 55-65°C using vacuum drying for 1-3 hours.

[0059] In this invention, the Co source, Ni source, and Ru source may exist with or without bound water. Cobalt nitrate may be Co(NO3)2·6H2O, nickel nitrate may be Ni(NO3)2·6H2O, and ruthenium chloride may be RuCl3·3H2O. In this invention, the amounts of cobalt nitrate, nickel nitrate, and ruthenium chloride are respectively calculated in the form of Co(NO3)2·6H2O, Ni(NO3)2·6H2O, and RuCl3·3H2O.

[0060] A third aspect of the present invention provides a hydrogen evolution catalyst for water electrolysis prepared by the preparation method provided by the present invention.

[0061] A fourth aspect of the present invention provides a method for producing hydrogen by electrolysis of water, wherein the method includes: passing electricity through an electrolyte in the presence of a hydrogen evolution catalyst in water electrolysis to produce hydrogen gas; wherein the hydrogen evolution catalyst in water electrolysis is the hydrogen evolution catalyst in water electrolysis provided by the present invention.

[0062] The present invention will be described in detail below through examples and comparative examples. Unless otherwise specified, the methods used in the following examples are conventional; the reagents and materials used are commercially available unless otherwise specified.

[0063] The following examples illustrate the preparation of a catalyst for hydrogen evolution in water electrolysis.

[0064] Example 1

[0065] S1. Weigh 2.4 g of nickel nitrate and 9.6 g of cobalt nitrate into a 2 L beaker, then add 0.3 L of methanol solution and stir to dissolve, obtaining solution A. Weigh 13.12 g of 2-methylimidazole and dissolve it in a beaker containing 0.3 L of methanol solution, stirring to obtain solution B. Then, under stirring, add solution B to solution A and mix thoroughly. Stir the above solutions at room temperature for 24 h, centrifuge, and wash the product three times with anhydrous ethanol to obtain CoNi-ZIF precursor nanomaterials, which are then dried for later use. Place the dried CoNi-ZIF precursor nanomaterials in a tube furnace, heat to 700 °C at a rate of 5 °C / min under an argon atmosphere, maintain this temperature for 2 h, and then allow to cool naturally to room temperature to obtain CoNi-N doped carbon nanotube composite material.

[0066] S2. Weigh 30 mg of RuCl3 and dissolve it in 40 ml of NMP. Then add 0.3 g of CoNi-N doped carbon nanotube composite material black powder, sonicate for 2 hours, then heat and stir at 60 °C for 12 hours. Then slowly add 2 ml of 10% (10 g / 100 mL) NaHB4 / NMP solution, stir at room temperature for 1 hour, then add 10 ml of acetone solution, centrifuge, wash three times with ethanol solution, and dry under vacuum at 60 °C for 2 hours. The Ru-Co-Ni water electrolysis hydrogen evolution catalyst is thus prepared.

[0067] The morphological characterization of the Ru-Co-Ni water electrolysis hydrogen evolution catalyst is shown in the transmission electron microscope (TEM) and high-resolution TEM images, respectively. Figure 1 and Figure 2 As shown, by Figure 1 It can be seen that the catalyst sample has a carbon nanotube composite porous carbon-based structure; from Figure 2 It can be seen that the average particle size of the Ru-supported catalyst is 3 nm. ICP analysis shows that the catalyst sample composition is: C: 51.44 wt%, Co: 41.52 wt%, Ni: 3.28 wt%, N: 2.28 wt%, Ru: 1.48 wt%.

[0068] The X-ray photoelectron spectroscopy characterization results of the nitrogen element in the Ru-Co-Ni water electrolysis hydrogen evolution catalyst sample are as follows: Figure 3 As shown, by Figure 3 It can be seen that pyridine N and pyrrole N at 398.8 eV and 400.9 eV have better electron-donating ability, which is beneficial to the hydrogen evolution process. The proportions of the two are 44.1 wt% and 26.8 wt% of the total number of N, respectively.

[0069] Example 2

[0070] The Ru-Co-Ni water electrolysis hydrogen evolution catalyst was prepared according to the method of Example 1, except that the weight ratio of nickel nitrate, cobalt nitrate, and 2-methylimidazole was different. Specifically, the method of "weighing 0.2 g of nickel nitrate and 0.8 g of cobalt nitrate in a 2 L beaker, then adding 50 mL of methanol solution and stirring to dissolve, obtaining solution A. Weighing 1.64 g of 2-methylimidazole and dissolving it in a beaker containing 50 mL of methanol solution and stirring to obtain solution B" was replaced with "weighing 2.4 g of nickel nitrate and 9.6 g of cobalt nitrate in a 2 L beaker, then adding 0.3 L of methanol solution and stirring to dissolve, obtaining solution A. Weighing 13.12 g of 2-methylimidazole and dissolving it in a beaker containing 0.3 L of methanol solution and stirring to obtain solution B". The Ru-Co-Ni water electrolysis hydrogen evolution catalyst was thus obtained.

[0071] According to ICP analysis, the catalyst sample composition is C: 51.58 wt%, Co: 40.84 wt%, Ni: 3.16 wt%, N: 2.37 wt%, Ru: 2.05 wt%.

[0072] Transmission electron microscopy (TEM) images and high-resolution TEM images of the Ru-Co-Ni water electrolysis hydrogen evolution catalyst are shown below. Figure 4 and Figure 5 As shown, by Figure 4 It can be seen that the catalyst sample has a carbon nanotube composite porous carbon-based structure, and the carbon nanotube structure is more slender. Figure 5 It can be seen that Ru is uniformly dispersed on the substrate surface, and the average particle size of the loaded Ru is 3.5 nm.

[0073] Example 3

[0074] The Ru-Co-Ni water electrolysis hydrogen evolution catalyst was prepared according to the method in Example 1, except that the calcination temperature of the CoNi-ZIF precursor nanomaterial was different. Specifically, in S1, "heated to 800°C at a rate of 5°C / min under an argon atmosphere" was replaced with "heated to 700°C at a rate of 5°C / min under an argon atmosphere". The Ru-Co-Ni water electrolysis hydrogen evolution catalyst was thus obtained.

[0075] According to ICP analysis, the catalyst sample composition is C: 49.72 wt%, Co: 41.28 wt%, Ni: 3.19 wt%, N: 2.31 wt%, Ru: 3.5 wt%; the average particle size of the supported Ru is 3 nm.

[0076] Example 4

[0077] The Ru-Co-Ni water electrolysis hydrogen evolution catalyst was prepared according to the method in Example 1, except that the calcination temperature of the CoNi-ZIF precursor nanomaterial was different. Specifically, in S1, "heated to 900°C at a rate of 5°C / min under an argon atmosphere" was replaced with "heated to 700°C at a rate of 5°C / min under an argon atmosphere". The Ru-Co-Ni water electrolysis hydrogen evolution catalyst was thus obtained.

[0078] According to ICP analysis, the catalyst sample composition is C: 49.05wt%, Co: 40.92wt%, Ni: 3.13wt%, N: 2.44wt%, Ru: 4.46wt%; the average particle size of the supported Ru is 2.5nm.

[0079] Example 5

[0080] The Ru-Co-Ni water electrolysis hydrogen evolution catalyst was prepared according to the method in Example 1, except that the calcination temperature of the CoNi-ZIF precursor nanomaterial was different. Specifically, in S1, "heated to 1000°C at a rate of 5°C / min under an argon atmosphere" was replaced with "heated to 700°C at a rate of 5°C / min under an argon atmosphere". The Ru-Co-Ni water electrolysis hydrogen evolution catalyst was thus obtained.

[0081] According to ICP analysis, the catalyst sample composition is C: 50.69wt%, Co: 41.94wt%, Ni: 3.43wt%, N: 2.57wt%, Ru: 1.37wt%; the average particle size of the supported Ru is 2.5nm.

[0082] Example 6

[0083] The Ru-Co-Ni water electrolysis hydrogen evolution catalyst was prepared according to the method of Example 1, except that the weight ratio of nickel nitrate, cobalt nitrate, and 2-methylimidazole was the same, but the total concentration in methanol was different. Specifically, in S1, the following was replaced with "Weigh 0.6g of nickel nitrate and 2.4g of cobalt nitrate into a 2L beaker, then add 50mL of methanol solution and stir to dissolve, obtaining solution A. Weigh 3.27g of 2-methylimidazole and dissolve it in a beaker containing 50mL of methanol solution, and stir to obtain solution B": This replaced "Weigh 2.4g of nickel nitrate and 9.6g of cobalt nitrate into a 2L beaker, then add 0.3L of methanol solution and stir to dissolve, obtaining solution A. Weigh 13.12g of 2-methylimidazole and dissolve it in a beaker containing 0.3L of methanol solution, and stir to obtain solution B". The Ru-Co-Ni water electrolysis hydrogen evolution catalyst was thus obtained.

[0084] According to ICP analysis, the catalyst sample composition is C: 52.12 wt%, Co: 41.13 wt%, Ni: 3.25 wt%, N: 2.34 wt%, Ru: 1.16 wt%; the average particle size of the supported Ru is 3 nm.

[0085] Comparative Example 1

[0086] The Ru-Co-Ni water electrolysis hydrogen evolution catalyst was prepared according to the method in Example 1, except that the calcination temperature of the CoNi-ZIF precursor nanomaterial was different. Specifically, in S1, "heated to 600°C at a rate of 5°C / min under an argon atmosphere" was replaced with "heated to 700°C at a rate of 5°C / min under an argon atmosphere". The Ru-Co-Ni water electrolysis hydrogen evolution catalyst was obtained, and no carbon nanotube structure (not shown in the text) was formed in the catalyst.

[0087] According to ICP analysis, the catalyst sample composition is C: 51.78wt%, Co: 42.04wt%, Ni: 3.46wt%, N: 2.21wt%, Ru: 0.52wt%; the average particle size of the supported Ru is 2nm.

[0088] Comparative Example 2

[0089] The Ru-Co-Ni water electrolysis hydrogen evolution catalyst was prepared according to the method in Example 1, except that the Ru loading process did not employ in-situ ion adsorption and reduction, but instead used a traditional aqueous solution impregnation method. Specifically, in S2, 30 mg of RuCl3 was weighed and dissolved in 40 ml of deionized water, then 0.3 g of CoNi-N doped carbon nanotube composite material was added, followed by stirring at room temperature for 2 hours and rotary evaporation drying at 60 °C for 1 hour. The Ru-Co-Ni water electrolysis hydrogen evolution catalyst was thus obtained.

[0090] According to ICP analysis, the catalyst sample composition is C: 49.49 wt%, Co: 40.27 wt%, Ni: 3.13 wt%, N: 2.07 wt%, Ru: 5.04 wt%; the average particle size of the supported Ru is 25 nm.

[0091] Test Example 1

[0092] The catalysts prepared in each example and comparative example were thoroughly ground. 10 mg of catalyst was weighed and added to 1 mL of an ethanol solution containing Nafion (4% by volume) and 1 mL of isopropanol solution. The mixture was then ultrasonically dispersed. 20 μL of the dispersion (0.2 mg catalyst) was measured and added dropwise to a rotating disk electrode for HER performance determination. 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 the electrolyte. Subsequently, the three-electrode test system was assembled, setting the voltage test range to -0.1 V to 0.1 V (vs. RHE) and the number of test cycles to 20 cycles to ensure complete sample activation and full exposure of active sites. Then, H2 was introduced into the electrolyte using a hydrogen generator for 30 minutes to completely saturate the electrolyte with H2. LSV testing was performed at 0 V to -0.6 V. Using 1 mol / L KOH as the electrolyte, at 10 mA / cm 2 The HER overpotential of the catalyst was measured at the specified current density. The results are shown in Table 1. The AC impedance of the catalysts prepared in Example 1 and Comparative Example 1 was measured, and the results are as follows: Figure 6 As shown.

[0093] Table 1

[0094] serial number Overpotential, mV Example 1 60 Example 2 48 Example 3 53 Example 4 55 Example 5 78 Example 6 70 Comparative Example 1 86 Comparative Example 2 123

[0095] The AC impedance test results of the catalysts prepared in Example 1 and Comparative Example 1 are as follows: Figure 6 As shown, by Figure 6 It can be seen that the AC impedance test result of the catalyst prepared in Example 1 is 56 ohms. Under the same test conditions, the AC impedance test result of the catalyst prepared in Comparative Example 1 without carbon nanotube formation is 64 ohms, indicating that the formation of carbon nanotubes improves the charge conduction ability.

[0096] The catalysts prepared in Examples 1-6 of this application all exhibited low HER overpotentials, below 78 mV. In Comparative Example 1, the calcination temperature of the CoNi-ZIF precursor nanomaterial was reduced to 600°C, and no carbon nanotube structure was formed in the catalyst. In Comparative Example 2, the Ru loading process did not employ in-situ ion adsorption and reduction; instead, a conventional aqueous solution impregnation method was used, resulting in a significantly increased average particle size of the loaded Ru. Compared to Examples 1-6, the overpotentials of the catalysts prepared in Comparative Examples 1 and 2 were significantly increased. Furthermore, in Example 5, the calcination temperature of the CoNi-ZIF precursor nanomaterial was increased to 1000°C, and in Example 6, the total concentrations of nickel nitrate, cobalt nitrate, and 2-methylimidazole in methanol were varied. Compared to Example 1, the HER overpotentials of the catalysts prepared in Examples 5 and 6 were both increased. This indicates that the calcination temperature of the CoNi-ZIF precursor nanomaterial meets the preferred conditions, and the total concentration of nickel nitrate, cobalt nitrate, and 2-methylimidazole in the solvent during the preparation of the CoNi-ZIF precursor nanomaterial meets the preferred conditions, which can further improve the hydrogen evolution performance of the catalyst.

[0097] 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. A catalyst for hydrogen evolution through water electrolysis, characterized in that, The catalyst contains Ru, Co, Ni, C and N; wherein, C exists in the catalyst in the form of carbon nanotubes; the content of Ru in the catalyst is 0.1-5 wt%, and the average particle size of Ru is 2-5 nm; The hydrogen evolution catalyst has a Ru-Co-Ni ternary metal composite carbon nanotube structure, in which pyridine nitrogen on the surface of the carbon nanotube structure forms M-Nx active sites with the metal. The catalyst contains 22-50 wt% Co. The catalyst contains 1-10 wt% Ni.

2. The catalyst according to claim 1, characterized in that, The catalyst contains 49-75 wt% C.

3. The catalyst according to claim 1 or 2, characterized in that, The catalyst contains 1-5 wt% N.

4. A method for preparing a hydrogen evolution catalyst for water electrolysis according to any one of claims 1-3, characterized in that, The preparation method includes the following steps: S1. In the presence of the first solvent, the Co source, Ni source and nitrogen-containing organic ligand are mixed and reacted to obtain the precursor. S2. The precursor is heated in the presence of a protective gas; the heating temperature is greater than or equal to 700°C. S3. In the presence of the second solvent, the product obtained in S2 and the Ru source are mixed for the second time. Then, the mixture after the second mixing is mixed with the reducing agent for the third time and an in-situ reduction reaction is carried out.

5. The preparation method according to claim 4, characterized in that, In S1, the Co source, the Ni source, and the nitrogen-containing organic ligand are mixed in the first mixture at a weight ratio of (3.5-5.5):1:(4-10).

6. The preparation method according to claim 4, characterized in that, The temperature of the first reaction is 20-30℃; the time is 20-30h.

7. The preparation method according to claim 4, characterized in that, Based on the total weight of the Co source, the Ni source, and the nitrogen-containing organic ligand, the amount of the first solvent used is 20-40 mL.

8. The preparation method according to claim 4, characterized in that, The Co source is selected from water-soluble cobalt salts.

9. The preparation method according to claim 8, characterized in that, The Co source is cobalt nitrate.

10. The preparation method according to claim 4, characterized in that, The Ni source is selected from water-soluble nickel salts.

11. The preparation method according to claim 10, characterized in that, The Ni source is nickel nitrate.

12. The preparation method according to claim 4, characterized in that, The nitrogen-containing organic ligand is 2-methylimidazole.

13. The preparation method according to claim 4, characterized in that, The first solvent is selected from C1-C4 monohydric alcohols.

14. The preparation method according to claim 13, characterized in that, The first solvent is methanol.

15. The preparation method according to claim 4, characterized in that, In S2, the heating conditions include: heating to 700-900°C at a rate of 4-7°C / min, and maintaining the temperature at 700-900°C for 1.5-2.5 hours.

16. The preparation method according to claim 4, characterized in that, In S3, the product obtained in S2 and the Ru source are mixed in the second mixture at a weight ratio of (8-12):

1.

17. The preparation method according to claim 4, characterized in that, The conditions for the second mixing include a temperature of 55-65°C and a time of 10-15 hours.

18. The preparation method according to claim 4, characterized in that, The Ru source is selected from water-soluble Ru salts.

19. The preparation method according to claim 18, characterized in that, The Ru source is RuCl3.

20. The preparation method according to claim 4, characterized in that, The second solvent is selected from weakly basic organic solvents.

21. The preparation method according to claim 20, characterized in that, The second solvent is N-methylpyrrolidone.

22. The preparation method according to claim 4, characterized in that, Based on a total weight of 1g for the product obtained in S2 and the Ru source, the amount of the second solvent used is 115-125mL.

23. The preparation method according to claim 4, characterized in that, In S3, the reducing agent is NaHB4.

24. The preparation method according to claim 4, characterized in that, Based on a Ru source weight of 1g, the amount of reducing agent used is 5-7g.

25. The preparation method according to claim 4, characterized in that, The in-situ reduction reaction is carried out at a temperature of 20-30℃ for 0.5-1.5 hours.

26. A method for producing hydrogen by electrolysis of water, characterized in that, The method includes: passing electricity through an electrolyte in the presence of a water electrolysis hydrogen evolution catalyst to produce hydrogen gas; wherein the water electrolysis hydrogen evolution catalyst is the water electrolysis hydrogen evolution catalyst according to any one of claims 1-3.

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