Nickel-iron-cobalt catalyst for AEM water electrolysis hydrogen production as well as preparation method and application of nickel-iron-cobalt catalyst

Abstract

The invention provides a nickel-iron-cobalt catalyst for AEM water electrolysis hydrogen production as well as a preparation method and application of the nickel-iron-cobalt catalyst. The preparation method of the nickel-iron-cobalt catalyst for AEM water electrolysis hydrogen production comprises the following steps: S1, dissolving nickel salt in water to obtain a nickel-containing solution, dissolving iron salt in water to obtain an iron-containing solution, dissolving cobalt salt in water to obtain a cobalt-containing solution, and dissolving sodium borohydride in water to obtain a sodium borohydride solution; s2, uniformly mixing the nickel-containing solution, the iron-containing solution and the cobalt-containing solution to obtain a mixed solution; s3, mixing and stirring the mixed solution and a sodium borohydride solution to generate a large amount of precipitate, and further cleaning, drying and grinding the precipitate to obtain the nickel-cobalt-iron oxygen evolution catalyst. The nickel-iron-cobalt catalyst provided by the invention can replace an iridium oxide (ruthenium) catalyst. The catalyst has low overpotential when applied to AEM water electrolysis hydrogen production, long-time effective electrolytic reaction can be guaranteed, and meanwhile the cost of an AEM electrolytic cell is remarkably reduced.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a nickel-iron-cobalt catalyst for AEM water electrolysis to produce hydrogen, its preparation method, and its application. Background Technology

[0002] Hydrogen has wide applications in energy, industry, defense, scientific research, and medicine. However, fossil fuel-based hydrogen production technologies consume non-renewable energy, which is detrimental to sustainable development. Currently, most renewable energy sources are converted into electricity, such as wind and solar power. Hydrogen production through water electrolysis can utilize the electricity generated from these clean energy sources to produce hydrogen. There are currently four main reported methods for hydrogen production through water electrolysis: alkaline water electrolysis (ALK), proton exchange membrane water electrolysis (PEM), anion exchange membrane water electrolysis (AEM), and solid oxide electrolysis (SOEC). However, considering economic costs, hydrogen purity, and energy consumption, only ALK and PEM are currently used on an industrial scale for hydrogen production. ALK produces hydrogen with low purity and high energy consumption, requiring a stable power supply, having a slow response time, and facing the risk of alkaline leakage, thus failing to meet green environmental protection requirements. In contrast, the anode of the PEM electrolyzer is in a strongly acidic environment, which corrodes most non-precious metals, leading to electrolyzer damage. The oxygen evolution catalyst and electrode materials at the anode must possess high stability and acid resistance. Titanium is generally used as the electrode material and iridium as the precious metal catalyst. However, iridium is scarce and expensive. AEM (Alternating Electrolysis) water electrolysis technology combines the advantages of ALK (Alternating Current) and PEM (Protein Evolution) technologies, and has been widely studied due to its low cost, high current density, high hydrogen purity, fast response speed, and safety. However, currently, the commonly used anode catalysts for AEM water electrolysis are iridium oxide and ruthenium oxide catalysts. These precious metals are scarce, expensive, and exhibit relatively low stability when applied to hydrogen production via AEM water electrolysis.

[0003] Therefore, there is an urgent need to develop low-cost, high-stability non-precious metal-based catalysts to realize the low-cost, large-scale, and green application of AEM water electrolysis for hydrogen production, and to promote the sustainable development of the renewable energy hydrogen production industry. Summary of the Invention

[0004] This invention addresses the problems of high cost and low stability of current precious metal catalysts by providing a nickel-iron-cobalt catalyst for AEM water electrolysis to produce hydrogen, its preparation method, and its application.

[0005] The technical method of the present invention is as follows: A method for preparing a nickel-iron-cobalt catalyst for hydrogen production by AEM water electrolysis includes: S1. Dissolve nickel salt in water to obtain a nickel-containing solution; dissolve iron salt in water to obtain an iron-containing solution; dissolve cobalt salt in water to obtain a cobalt-containing solution; dissolve sodium borohydride in water to obtain a sodium borohydride solution. S2. Mix the nickel-containing solution, iron-containing solution and cobalt-containing solution evenly to obtain a mixed solution; S3. The mixture is mixed with sodium borohydride solution and stirred to produce a large amount of precipitate. The precipitate is then washed, dried and ground to obtain the nickel-cobalt-iron oxygen evolution catalyst.

[0006] Optionally, in the mixture, the molar ratio of nickel, iron, and cobalt is 1:1:1 to (1~10):(1~9):(1~8). The nickel salt, iron salt, and cobalt salt are selected from one or more of chlorides, nitrates, sulfates, and acetates. The average particle size of the nickel-iron-cobalt catalyst is 10~30 nm.

[0007] Optionally, in step S2, the mixture is dispersed by ultrasonication for a time of 1 to 120 minutes.

[0008] Optionally, in step S3, the mixing and stirring can be performed by magnetic stirring, mechanical stirring, or ultrasonic mixing.

[0009] This invention provides a nickel-iron-cobalt catalyst for hydrogen production by AEM water electrolysis, wherein the nickel-iron-cobalt catalyst for hydrogen production by AEM water electrolysis is prepared by the above-described preparation method.

[0010] Optionally, the iron-cobalt-nickel catalyst is uniformly dispersed nanoparticles.

[0011] This invention also provides the application of a nickel-iron-cobalt catalyst in anion exchange membrane electrolysis of water to produce hydrogen. Further, the electrolysis temperature is 30-90°C. o C, the electrolysis current is 0.1~3A / cm 2 .

[0012] The beneficial effects of this invention are: I. The nickel-iron-cobalt catalyst provided by this invention can replace the iridium (ruthenium) oxide catalyst. When applied to AEM water electrolysis for hydrogen production, this catalyst exhibits a low overpotential and ensures a long-term effective electrolysis reaction, while significantly reducing the cost of the AEM electrolyzer.

[0013] II. The non-precious metal nickel-iron-cobalt catalyst of the present invention has a simple synthesis method, is environmentally friendly, and is easy to prepare in batches. Attached Figure Description

[0014] Figure 1 This is a flowchart illustrating the preparation and application of the AEM electrolysis water-to-hydrogen catalyst of this invention. Figure 2This is a transmission electron microscope image of the nickel-iron-cobalt catalyst prepared in the embodiments of the present invention; Figure 3 This is a schematic diagram of the structure of the AEM water electrolysis hydrogen production device in this invention; Figure 4 This is a comparison diagram of the polarization curves of Embodiment 1 and Comparative Example 1 under 70°C conditions; Figure 5 This is a comparison diagram of the polarization curves of Embodiment 1 and Embodiment 2 of the present invention. Attached image description: 1. Fuel cell stack; 2. DC power supply; 3. Ammeter; 4. Voltmeter; 5. Water pump; 6. Alkali solution; 7. Gas-liquid conduit. Detailed Implementation

[0016] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] This invention provides a method for preparing a nickel-iron-cobalt catalyst for AEM water electrolysis to produce hydrogen, such as... Figure 1 As shown, it includes: S1. Dissolve nickel salt in water to obtain a nickel-containing solution; dissolve iron salt in water to obtain an iron-containing solution; dissolve cobalt salt in water to obtain a cobalt-containing solution; dissolve sodium borohydride in water to obtain a sodium borohydride solution.

[0018] In this embodiment, the molar ratio of nickel, iron, and cobalt in the mixture is 1:1:1 to (1~10):(1~9):(1~8). For example, the molar ratio of nickel, iron, and cobalt is 2:3:5, 3:4:6, or 4:6:7.

[0019] In this embodiment, the nickel salt, iron salt, and cobalt salt are selected from one or more of chlorides, nitrates, sulfates, and acetates.

[0020] In this embodiment, the ratio of nickel salt to water is 4~6g:8~12ml; the ratio of iron salt to water is 1~2g:3~5ml; the ratio of cobalt salt to water is 2~3g:4~7ml; and the ratio of sodium borohydride to water is 5~6g:65~75ml.

[0021] In this embodiment, the water may be deionized water.

[0022] S2. Mix the nickel-containing solution, iron-containing solution and cobalt-containing solution evenly to obtain a mixed solution.

[0023] In this embodiment, the mixture is dispersed by ultrasonication for a time ranging from 1 to 120 minutes. For example, the ultrasonic dispersion time is 25 minutes, 30 minutes, or 35 minutes.

[0024] S3. The mixture is mixed with sodium borohydride solution and stirred to produce a large amount of precipitate. The precipitate is then washed, dried and ground to obtain the nickel-cobalt-iron oxygen evolution catalyst.

[0025] In this embodiment, the mixing and stirring are performed by magnetic stirring, mechanical stirring, or ultrasonic mixing.

[0026] In this embodiment, cleaning is performed using filtered water. Drying and grinding are carried out using conventional procedures in the art.

[0027] This invention provides a nickel-iron-cobalt catalyst for hydrogen production by AEM water electrolysis, wherein the nickel-iron-cobalt catalyst for hydrogen production by AEM water electrolysis is prepared by the above-described preparation method.

[0028] In this embodiment, the nickel-iron-cobalt catalyst is an alloy particle with an average particle size of 10~30 nm.

[0029] This invention also provides an application of a nickel-iron-cobalt catalyst in anion exchange membrane (AEM) water electrolysis for hydrogen production. In this application, an AEM water electrolysis hydrogen production device is used. The device includes an anolyte; the preparation of the anolyte involves mixing the aforementioned nickel-iron-cobalt catalyst for AEM water electrolysis, ethanol, and a binder, followed by ultrasonic dispersion to obtain the anolyte.

[0030] In this embodiment, the water may be deionized water.

[0031] In this embodiment, water and ethanol are mixed at a volume ratio of 1:15~25, and then nickel-iron-cobalt catalyst powder is added. A binder solution is then added until the weight percentage of binder to nickel-iron-cobalt is 25~35wt%. After ultrasonic dispersion, an anolyte is obtained.

[0032] In this embodiment, the apparatus further includes a catholyte; the preparation of the catholyte includes: mixing a cathode catalyst, ethanol, a binder, and an aqueous solvent, followed by ultrasonic dispersion to obtain the catholyte. Here, the cathode catalyst includes one or more of NiCuP, Co3O4, Ni-O-Pt, Fe-CoMoP, Pt, or Pt / C.

[0033] In this embodiment, ethanol and water are mixed at a volume ratio of 1:15~25, and then cathode catalyst powder is added. A binder solution is then added until the weight percentage of binder to Pt / C is 25~35wt%. After ultrasonic dispersion, a cathode liquid is obtained.

[0034] In this embodiment, the device further includes a diffusion layer. The diffusion layer is prepared by loading an anodic catalyst or a cathode catalyst onto a substrate, wherein the substrate comprises nickel foam and / or nickel felt, and the loading of the anodic catalyst (nickel-iron-cobalt) is 0.1~10 mg / cm³. 2 The loading of the cathode catalyst is 0.1 ~ 5 mg / cm³. 2 For example, anolyte is sprayed onto an anode substrate (such as nickel foam), and catholyte is sprayed onto a cathode substrate (such as nickel felt).

[0035] In this embodiment, the device further includes one or more of the following: an end plate, an insulating layer, an electrode plate, a bipolar plate, a gasket, a membrane electrode, and a gas-liquid conduit. Figure 3 As shown, the device includes: a fuel cell stack 1, a DC power supply 2, an ammeter 3, a voltmeter 4, a water pump 5, an alkaline solution 6, and a gas-liquid conduit 7. The alkaline solution 6 in the device contains KOH, with a concentration of 0.1M to 2M.

[0036] In this embodiment, the electrolysis temperature is 30~90°C. o C, the electrolysis current is 0.1~3A / cm 2 For example, the temperature for electrolysis can be 40°C. o C, 50 o C, 60 o C, the electrolysis current can be 1 A / cm 2 2A / cm 2 .

[0037] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0038] The present invention will be described in detail below through embodiments and experimental examples. However, these are merely examples and do not limit the present invention in any way.

[0039] Example 1 (1) Preparation of nickel-iron-cobalt catalyst: Solution a was prepared by dissolving 4.05 g of nickel chloride hexahydrate in 8.52 ml of water; solution b was prepared by dissolving 1.45 g of ferric chloride in 4.47 ml of water; and solution c was prepared by dissolving 2.02 g of cobalt chloride in 4.25 ml of water. The molar ratio of Ni:Fe:Co was approximately 2:1:1. Solutions a, b, and c were mixed thoroughly in a beaker to prepare a mixed salt solution d, which was then ultrasonically dispersed for 30 minutes. Reduction solution e was prepared by dissolving 5.29 g of sodium borohydride in 70 ml of water. Solution e was added to solution d under vigorous stirring to initiate the reaction. After the reaction was complete, the resulting black precipitate was collected, washed with water, dried, and ground to obtain nickel-iron-cobalt catalyst powder.

[0040] TEM test: such as Figure 2 As shown, the catalyst obtained is a uniformly dispersed alloy particle with a particle size distribution between 10 and 30 nm.

[0041] (2) Electrode preparation: Anodic solution: Water and ethanol are mixed at a volume ratio of 1:20, the above-mentioned nickel-iron-cobalt powder is added, and then a binder solution is added. The weight percentage of binder to nickel-iron-cobalt is controlled at 30 wt%, and the solution is prepared by ultrasonic dispersion.

[0042] Cathodic solution: Ethanol and water are mixed at a volume ratio of 1:20, Pt / C powder is added, and binder solution is added until the weight percentage of PT-13 and Pt / C is 33wt%, and then ultrasonically dispersed.

[0043] Spraying: Anodic and cathodic solutions were sprayed onto one side of nickel foam and nickel felt respectively using an ultrasonic spraying machine to obtain a cathode Pt / C loading of 0.5 mg / cm³. 2 With an anode nickel-iron-cobalt loading of 3 mg / cm³ 2 The diffusion layer.

[0044] (3) Electrolysis performance test: After assembling the end plates, insulating layer, electrode plates, bipolar plates, gaskets, diffusion layer, and membrane electrode into a fuel cell stack, prepare a 1 MkOH alkaline solution. Then, through a gas-liquid conduit... Figure 3 Connect the devices in the order shown, and control the alkali solution temperature at 70°C. o C. After electrolysis stabilizes, the polarization curve is measured to obtain the overpotential under different current densities, such as... Figure 4 As shown, the overpotential of nickel-iron-cobalt is significantly lower than that of the iridium oxide catalyst in Comparative Example 1.

[0045] Example 2 (1) Preparation of nickel-iron-cobalt catalyst: 5.71 g of nickel chloride hexahydrate was dissolved in 12.01 ml of water; 1.95 g of ferric chloride was dissolved in 3 ml of water; and 2.86 g of cobalt chloride was dissolved in 6.01 ml of water. At this point, the molar ratio of Ni:Fe:Co was approximately 4:1:1. Solutions a, b, and c were mixed thoroughly in a beaker to prepare a mixed salt solution d. 5.29 g of sodium borohydride was mixed with 70 ml of water to prepare solution e. Solution e was added to solution d under vigorous stirring to initiate the reaction. After the reaction was complete, the resulting black precipitate was collected, washed with water, dried, and ground to obtain nickel-iron-cobalt catalyst powder.

[0046] (2) Electrode preparation: Anodic solution: Water and ethanol are mixed at a volume ratio of 1:20, the above-mentioned nickel-iron-cobalt powder is added, and then a binder solution is added. The weight percentage of binder to nickel-iron-cobalt is controlled at 30 wt%, and the solution is prepared by ultrasonic dispersion.

[0047] Cathodic solution: Ethanol and water are mixed at a volume ratio of 1:20, Pt / C powder is added, and binder solution is added until the weight percentage of binder to Pt / C is 33wt%, and then ultrasonically dispersed.

[0048] Spraying: Anodic and cathodic solutions were sprayed onto one side of nickel foam and nickel felt respectively using an ultrasonic spraying machine to obtain a cathode Pt / C loading of 0.5 mg / cm³. 2 With an anode nickel-iron-cobalt loading of 3 mg / cm³ 2 The diffusion layer.

[0049] (3) Electrolysis performance test: After assembling the end plates, insulating layer, electrode plates, bipolar plates, gaskets, diffusion layer, and membrane electrode into a fuel cell stack, prepare a 1 MkOH alkaline solution. Then, through a gas-liquid conduit... Figure 3 Connect the devices in the order shown, and control the alkali solution temperature at 70°C. o C. After electrolysis stabilizes, the polarization curve is measured to obtain the overpotential under different current densities, such as... Figure 5 As shown, the overpotential of the catalyst with a nickel-iron-cobalt atomic ratio of 2:1:1 is lower than that of the catalyst with a nickel-iron-cobalt atomic ratio of 4:1:1.

[0050] Comparative Example 1 (1) Electrode preparation: Anodic solution: Ethanol and water are mixed at a volume ratio of 1:2, then IrO2 powder is added, and then binder solution is added until the weight percentage of binder to IrO2 is 30wt%. The solution is then ultrasonically dispersed to obtain the solution.

[0051] Cathodic solution: ethanol and water are mixed at a volume ratio of 1:20, Pt / C powder is added, and then binder solution is added until the weight percentage of binder to Pt / C is 33wt%. The mixture is then ultrasonically dispersed to obtain the solution.

[0052] Spraying: Anodic and cathodic solutions were sprayed onto one side of nickel foam and nickel felt respectively using an ultrasonic spraying machine to obtain a cathode Pt / C loading of 0.5 mg / cm³. 2 With an anode IrO2 loading of 1.5 mg / cm³ 2 The diffusion layer.

[0053] (2) Electrolysis performance test: After assembling the end plates, insulating layer, electrode plates, bipolar plates, gaskets, diffusion layer, and membrane electrode into a fuel cell stack, prepare a 1 MkOH alkaline solution. Then, through a gas-liquid conduit... Figure 3 The devices are connected in the order shown, and the alkali solution temperature is controlled at 70 degrees Celsius. After electrolysis stabilizes, the polarization curve is measured to obtain the overpotential under different current densities, such as... Figure 4 As shown, the overpotential of nickel-iron-cobalt catalyst is significantly lower than that of iridium oxide catalyst.

[0054] Comparative Example 2 (1) Electrode preparation: Anodic solution: Deionized water and ethanol are mixed at a volume ratio of 1:20, nickel-iron-cobalt powder is added, and then binder solution is added until the weight percentage of binder to nickel-iron-cobalt is 30 wt%. The solution is then ultrasonically dispersed to obtain the solution.

[0055] Cathodic solution: Ethanol and deionized water are mixed at a volume ratio of 1:20, Pt / C powder is added, and then binder solution is added until the weight percentage of binder to Pt / C is 33wt%. The solution is then ultrasonically dispersed to obtain the solution.

[0056] The anolyte and catholyte were respectively sprayed onto one side of nickel foam and nickel felt using an ultrasonic spraying machine, resulting in a cathode with a Pt / C loading of 0.5 mg / cm³. 2 With an anode nickel-iron-cobalt loading of 3 mg / cm³ 2 The diffusion layer.

[0057] After assembling the end plates, insulating layer, electrode plates, bipolar plates, gaskets, diffusion layer, and membrane electrode into an electrolytic cell, a 1M KOH alkaline solution is prepared. Then, it is transferred through a gas-liquid conduit... Figure 3 Connect the devices in the order shown, and control the alkali solution temperature at 70°C. o C. After electrolysis stabilizes, the polarization curve is measured to obtain the overpotential under different current densities, such as... Figure 5 As shown, the overpotential of the catalyst with a nickel-iron-cobalt atomic ratio of 2:1:1 is lower than that of the catalyst with a nickel-iron-cobalt atomic ratio of 4:1:1.

[0058] The above examples and comparative examples fully demonstrate that the NiFeCo ternary catalyst prepared by sodium borohydride in this invention, especially when the ratio is controlled at 2:1:1 and the particle size is in the range of 10~30nm, exhibits superior catalytic activity compared to traditional noble metal IrO2 in AEM water electrolysis for hydrogen production. Meanwhile, the electrode preparation process of this invention (dispersant ratio, loading, etc.) ensures the full utilization of the catalyst performance.

[0059] Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible subranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the range referred to.

[0060] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a nickel-iron-cobalt catalyst for AEM water electrolysis to produce hydrogen, characterized in that, include: S1. Dissolve nickel salt in water to obtain a nickel-containing solution; dissolve iron salt in water to obtain an iron-containing solution; dissolve cobalt salt in water to obtain a cobalt-containing solution; dissolve sodium borohydride in water to obtain a sodium borohydride solution. S2. Mix the nickel-containing solution, iron-containing solution and cobalt-containing solution evenly to obtain a mixed solution; S3. The mixture is mixed with sodium borohydride solution and stirred to produce a large amount of precipitate. The precipitate is then washed, dried and ground to obtain the nickel-cobalt-iron oxygen evolution catalyst.

2. The preparation method according to claim 1, characterized in that, In the mixture, the molar ratio of nickel, iron and cobalt is 1:1:1 to (1~10):(1~9):(1~8).

3. The preparation method according to claim 1, characterized in that, In step S2, the mixture is dispersed by ultrasonication for a time of 1 to 120 minutes.

4. The preparation method according to claim 1, characterized in that, In step S3, the mixing and stirring are performed by magnetic stirring, mechanical stirring, or ultrasonic mixing.

5. The preparation method according to claim 1, characterized in that, The nickel salt, iron salt, and cobalt salt are selected from one or more of chlorides, nitrates, sulfates, and acetates.

6. A nickel-iron-cobalt catalyst for hydrogen production via AEM water electrolysis, characterized in that, The nickel-iron-cobalt catalyst used for AEM water electrolysis to produce hydrogen is prepared by the preparation method described in any one of claims 1 to 5.

7. The nickel-iron-cobalt catalyst for AEM water electrolysis to produce hydrogen according to claim 6, characterized in that, The iron-cobalt-nickel catalyst is composed of uniformly dispersed nanoparticles.

8. The nickel-iron-cobalt catalyst for AEM water electrolysis to produce hydrogen according to claim 6, characterized in that, The average particle size of the nickel-iron-cobalt catalyst is 10~30 nm.

9. An application of the nickel-iron-cobalt catalyst as described in any one of claims 6-8 in anion exchange membrane water electrolysis for hydrogen production.

10. The application according to claim 9, characterized in that, The temperature for electrolysis is 30~90°C. o C, the electrolysis current is 0.1~3A / cm 2 .

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