Oxygen evolution electrode, preparation method and application thereof

Abstract

The application discloses an oxygen evolution electrode and a preparation method and application thereof, and comprises the following steps: mixing nickel nitrate, iron nitrate, isopropyl alcohol and glycerol to obtain a mixed solution; and placing a current collector in the mixed solution and performing ultrasonic treatment at normal temperature and pressure, wherein the frequency of the ultrasonic treatment is 20 kHz-80 kHz, and the ultrasonic treatment time is 2-10 h. The preparation method of the oxygen evolution electrode can prepare the oxygen evolution electrode loaded with a nickel-iron metal alkoxide in a short time at normal temperature and pressure through simple ultrasonic treatment, and the preparation method is simple and feasible, raw materials are cheap, and the method is environment-friendly, so that the method is suitable for industrial large-scale production and can effectively promote the development of green hydrogen production technology.

Description

Technical Field

[0001] This invention relates to the field of electrode catalysts, and more particularly to an oxygen evolution electrode, its preparation method, and its application. Background Technology

[0002] Hydrogen, with its high energy density, clean and environmentally friendly nature, and wide range of applications, is gradually becoming one of the important carriers of hydrogen energy. How to efficiently and safely achieve hydrogen-to-electricity conversion is the core key to the green hydrogen energy industry. Water electrolysis for hydrogen production is the upstream segment of the hydrogen energy industry, and its importance is rapidly increasing with the rise of renewable energy sources. Currently, the mature and large-scale commercial electrolysis method for hydrogen production is alkaline water electrolysis technology. However, the oxygen evolution reaction (OER) within this process has long been one of the biggest challenges in the field due to limitations such as slow kinetics, difficulty in increasing current density, and long-term safety concerns.

[0003] As the most efficient OER catalysts in alkaline electrolytes, nickel-iron-based catalysts have attracted widespread attention and made significant progress. However, most research on this type of catalyst remains at the laboratory scale, with complex synthesis methods and high costs limiting their large-scale commercial application. In-situ growth of nickel-iron-based catalysts on current collectors (such as nickel mesh, nickel felt, or nickel foam) has demonstrated activity and stability sufficient for industrial hydrogen production, but current preparation methods primarily involve water baths, electrodeposition, or solvothermal processes, which present challenges such as difficulties in scaling up, demanding growth conditions, uneven catalyst coverage, and environmental pollution.

[0004] Nickel-iron-based metal alkoxide catalysts are ideal alkaline OER catalysts, readily transforming in-situ into nickel-iron-based hydroxyl oxides during electrolysis. Their loose, amorphous, and defect-rich structure is highly conducive to exposing active sites. However, the synthesis of nickel-iron-based metal alkoxides currently relies entirely on solvothermal methods, requiring high-temperature, high-pressure, and long-duration synthesis conditions. Furthermore, the resulting powders cannot be directly used as electrodes for water electrolysis. A key problem urgently needs to be solved to achieve a simple and efficient method for directly and in-situ growing nickel-iron-based metal alkoxides on current collectors, thus enabling large-scale industrial hydrogen production. Summary of the Invention

[0005] The technical problem this invention aims to solve is to overcome the shortcomings of existing technologies in in-situ growth of nickel-iron-based metal alkoxides onto current collectors, including difficulties in large-scale production, harsh growth conditions, uneven catalyst coverage, and environmental pollution. This invention provides an oxygen evolution electrode, its preparation method, and its applications. This oxygen evolution electrode exhibits high oxygen evolution reaction activity and good stability. The preparation method of this oxygen evolution electrode not only allows for direct in-situ growth of nickel-iron-based metal alkoxides onto current collectors at room temperature and pressure within a short time, but also utilizes inexpensive raw materials, is environmentally friendly, and is suitable for large-scale industrial production.

[0006] This invention discloses a method for preparing an oxygen evolution electrode, which includes the following steps:

[0007] Nickel nitrate, ferric nitrate, isopropanol, and glycerol are mixed to obtain a mixture;

[0008] The current collector is placed in the mixture and ultrasonicated at room temperature and pressure. The frequency of the ultrasonication is 20kHz-80kHz and the duration of the ultrasonication is 2-10h.

[0009] Preferably, the molar ratio of nickel nitrate to ferric nitrate is (3-5):1.

[0010] Preferably, the nickel nitrate is nickel nitrate hexahydrate.

[0011] Preferably, the ferric nitrate is ferric nitrate nonahydrate.

[0012] Preferably, the concentration of nickel nitrate is 80-240 mmol / L, based on the millimoles of nickel nitrate contained in the total volume of the mixture per liter.

[0013] Preferably, the concentration of ferric nitrate is 30-50 mmol / L, based on the millimoles of ferric nitrate contained in the total volume of the mixture per liter.

[0014] Preferably, the volume ratio of isopropanol to glycerol is (10-30):1.

[0015] Preferably, the ambient temperature is 15℃-40℃, for example 25℃.

[0016] Preferably, the atmospheric pressure is 98 kPa-105 kPa, for example 101 kPa.

[0017] More preferably, the molar ratio of nickel nitrate to ferric nitrate is 4:1.

[0018] More preferably, the concentration of nickel nitrate is 160 mmol / L, based on the millimoles of nickel nitrate contained in the total volume of the mixture per liter.

[0019] More preferably, the concentration of ferric nitrate is 40 mmol / L, based on the millimoles of ferric nitrate contained in the total volume of the mixture per liter.

[0020] More preferably, the amount of isopropanol used is 100-300 mL, for example, 200 mL.

[0021] More preferably, the amount of glycerol used is 10-30 mL, for example 20 mL.

[0022] Preferably, the current collector is a nickel mesh, nickel felt, or nickel foam, such as nickel foam.

[0023] Preferably, the current collector has a size of 5cm × 5cm.

[0024] Preferably, the pore density of the current collector is 75 ppi-110 ppi.

[0025] Preferably, the thickness of the current collector is 0.5-1.5 mm, for example, 1 mm.

[0026] Preferably, the diameter of the pores in the oxygen evolution electrode is 100μm-1000μm.

[0027] In this invention, the surface roughness of the current collector can be conventional in the art.

[0028] Preferably, the current collector is cleaned before the ultrasound is performed.

[0029] More preferably, the cleaning method involves ultrasonically immersing the current collector in acetone, hydrochloric acid, deionized water, and anhydrous ethanol solutions, respectively, and then drying it.

[0030] More preferably, the sonication time in each solution is 2-10 minutes, for example, 5 minutes.

[0031] Preferably, the ultrasound is performed under a protective gas atmosphere.

[0032] More preferably, the protective gas is argon or nitrogen.

[0033] Preferably, the frequency of the ultrasound is 40kHz-80kHz.

[0034] Preferably, the ultrasound duration is 2-6 hours.

[0035] Preferably, after ultrasound, the current collector is rinsed and dried.

[0036] More preferably, the rinsing solution is anhydrous ethanol.

[0037] More preferably, the drying is carried out in a vacuum oven.

[0038] More preferably, the drying temperature is 50-70°C, for example, 60°C.

[0039] More preferably, the drying time is 10-15 hours, for example, 12 hours.

[0040] The present invention also discloses an oxygen evolution electrode, which is prepared by the above-described method for preparing an oxygen evolution electrode.

[0041] The present invention also discloses the application of the above-mentioned oxygen evolution electrode in the electrolysis of water to produce hydrogen.

[0042] The positive and progressive effects of this invention are as follows:

[0043] (1) The ultrasonic synthesis method used in the oxygen evolution electrode of the present invention utilizes the chemical energy provided by ultrasound. By adjusting the power of ultrasound to match the energy required for the change of chemical bonds in the chemical reaction process, the oxygen evolution electrode loaded with nickel-iron-based metal alkoxide can be prepared in a short time at room temperature and pressure. Moreover, the preparation method is simple and feasible, the raw materials are cheap, environmentally friendly, and suitable for large-scale industrial production, which can effectively promote the development of green hydrogen production technology.

[0044] (2) The oxygen evolution electrode of the present invention exhibits high oxygen evolution reaction activity and good stability. The oxygen evolution electrode prepared by the method of the present invention is loaded with nickel-iron-based metal alkoxides, which have good catalytic activity, reduce the reaction activation energy, and thus reduce the overpotential. In a preferred embodiment of the present invention, the current density can reach 500 mA / cm² at a voltage of 1.72 V. 2 The overpotential is only 490mV. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the experimental process in Embodiments 1 and 2 of the present invention.

[0046] Figure 2 This is a scanning electron microscope image of the oxygen evolution electrode of Comparative Example 3 of the present invention.

[0047] Figure 3 This is a scanning electron microscope image of the oxygen evolution electrode in Embodiment 1 of the present invention.

[0048] Figure 4 The oxygen evolution linear voltammetry curves are for the oxygen evolution electrodes of Examples 1-3 and Comparative Example 3 of this invention.

[0049] Figure 5 This is the stability curve of the oxygen evolution electrode in Embodiment 1 of the present invention. Detailed Implementation

[0050] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0051] The reagents and raw materials used in the following examples, such as nickel nitrate hexahydrate and ferric nitrate nonahydrate, are all commercially available.

[0052] The nickel foam used in the following examples has a pore density of 110 ppi and a thickness of 1 mm.

[0053] Example 1

[0054] (1) Dissolve nickel nitrate hexahydrate and ferric nitrate nonahydrate in 200 mL of isopropanol at a molar ratio of 4:1, and add 20 mL of glycerol to form a mixture. The concentration of nickel nitrate hexahydrate in the mixture is 160 mmol / L, and the concentration of ferric nitrate nonahydrate is 40 mmol / L.

[0055] (2) Place the 5cm×5cm nickel foam in acetone, hydrochloric acid, deionized water and anhydrous ethanol solutions respectively and sonicate for 5 minutes in each solution. After taking it out, blow it dry and then place it in the mixture of step (1) and continuously purge it with nitrogen gas. Then sonicate it continuously at 40kHz for 6 hours at a temperature of 25℃ and a pressure of 101kPa.

[0056] (3) Take out the foamed nickel after ultrasonic treatment in step (2), rinse it with anhydrous ethanol, and dry it in a vacuum oven at 60°C for 12 hours to obtain the oxygen evolution electrode.

[0057] Example 2

[0058] (1) Dissolve nickel nitrate hexahydrate and ferric nitrate nonahydrate in 200 mL of isopropanol at a molar ratio of 4:1, and add 20 mL of glycerol. The concentration of nickel nitrate hexahydrate in the mixture is 160 mmol / L, and the concentration of ferric nitrate nonahydrate is 40 mmol / L.

[0059] (2) Place the 5cm×5cm nickel foam in acetone, hydrochloric acid, deionized water and anhydrous ethanol solutions respectively for sonication for 5 minutes in each solution. After taking it out, blow it dry and then place it in the mixture of step (1) and continuously purge it with nitrogen gas. Then, sonicate it continuously at 20kHz for 6 hours at a temperature of 25℃ and a pressure of 101kPa.

[0060] (3) Take out the foamed nickel after ultrasonic treatment in step (2), rinse it with anhydrous ethanol, and dry it in a vacuum oven at 60°C for 12 hours to obtain the oxygen evolution electrode.

[0061] Example 3

[0062] (1) Dissolve nickel nitrate hexahydrate and ferric nitrate nonahydrate in 200 mL of isopropanol at a molar ratio of 4:1, and add 20 mL of glycerol. The concentration of nickel nitrate hexahydrate in the mixture is 160 mmol / L, and the concentration of ferric nitrate nonahydrate is 40 mmol / L.

[0063] (2) Place the 5cm×5cm nickel foam in acetone, hydrochloric acid, deionized water and anhydrous ethanol solutions respectively and sonicate for 5 minutes in each solution. After taking it out, blow it dry and then place it in the mixture of step (1) and continuously purge it with nitrogen gas. Then sonicate it continuously at 40kHz for 2 hours at a temperature of 25℃ and a pressure of 101kPa.

[0064] (3) Take out the foamed nickel after ultrasonic treatment in step (2), rinse it with anhydrous ethanol, and dry it in a vacuum oven at 60°C for 12 hours to obtain the oxygen evolution electrode.

[0065] Comparative Example 1

[0066] Take out a 5cm×5cm nickel foam after ultrasonic cleaning and place it in the mixed solution in step (1) of Example 1. Prepare it by hydrothermal method under the condition of keeping it at 160℃-180℃ for 8-10h.

[0067] Comparative Example 2

[0068] Other conditions were the same as in Example 1, except that nickel nitrate hexahydrate and ferric nitrate nonahydrate in a molar ratio of 4:1 were dissolved in 220 mL of deionized water. The results showed that an oxygen evolution electrode loaded with nickel-iron-based metal alkoxides could not be obtained.

[0069] Comparative Example 3

[0070] (1) Dissolve nickel nitrate hexahydrate and ferric nitrate nonahydrate in 200 mL of isopropanol at a molar ratio of 4:1, and add 20 mL of glycerol to form a mixture. The concentration of nickel nitrate hexahydrate in the mixture is 160 mmol / L, and the concentration of ferric nitrate nonahydrate is 40 mmol / L.

[0071] (2) Place the 5cm×5cm nickel foam in acetone, hydrochloric acid, deionized water and anhydrous ethanol solutions respectively and sonicate for 5 minutes in each solution. After taking it out, blow it dry and then place it in the mixture of step (1) and continuously purge it with nitrogen gas.

[0072] (3) Take out the foamed nickel after ultrasonic treatment in step (2), rinse it with anhydrous ethanol, and dry it in a vacuum oven at 60°C for 12 hours to obtain the oxygen evolution electrode.

[0073] The results showed that no material was generated on the nickel foam substrate, and it was impossible to obtain an oxygen evolution electrode loaded with nickel-iron-based metal alkoxides.

[0074] Example 1

[0075] Oxygen evolution reaction test:

[0076] The oxygen evolution reaction activity and stability of the oxygen evolution electrodes of Examples 1-3 and Comparative Example 3 were tested using a standard three-electrode system. The working electrode was the 1cm×1cm sample prepared above, the counter electrode was a platinum mesh, the reference electrode was Hg / HgO, the electrolyte was 1M KOH solution, and the electrochemical workstation used for the test was a GAMRY Reference 3000.

[0077] The experimental procedures of Examples 1 and 2 are illustrated in the diagram below. Figure 1 As shown.

[0078] The scanning electron microscope image of the oxygen evolution electrode in Comparative Example 3 is shown below. Figure 2 As shown, the surface morphology of the oxygen evolution electrode in Comparative Example 3 exhibits a pore structure of varying sizes, with pore diameters ranging from 100 μm to 1000 μm. The surface is smooth and free of any loading material.

[0079] The scanning electron microscope image of the oxygen evolution electrode in Example 1 is shown below. Figure 3 As shown. The surface morphology of the oxygen evolution electrode in Example 1 exhibits a porous structure of varying sizes, with pore diameters ranging from 100 μm to 1000 μm. Nickel-iron-based metal alkoxides are deposited or adhered on the surface of the nickel foam and between the pores, forming a uniform and rough coating.

[0080] The linear voltammetric curves of the oxygen evolution electrodes in Examples 1-3 and Comparative Example 3 are shown below. Figure 4 As shown, the oxygen evolution electrode in Example 1 can achieve a current density of 500 mA / cm² at a voltage of 1.72 V, compared to the reversible hydrogen electrode. 2 The theoretical potential for water electrolysis is 1.23V. However, in actual electrolysis, an overpotential exists, and the current density is approximately 500 mA / cm². 2 The potential at this time is 1.72V, and the overpotential is only 1.72V-1.23V=0.49V=490mV. The oxygen evolution electrodes of Examples 2 and 3 also exhibit certain oxygen evolution reaction activity, which is weaker than that of Example 1, but significantly stronger than that of the untreated oxygen evolution electrode of Comparative Example 3.

[0081] The stability curve of the oxygen evolution electrode in Example 1 is shown below. Figure 5 As shown. Its stability was evaluated using the chronoamperometry method at 300 mA / cm². 2 At the specified current density, the oxygen evolution electrode of Example 1 can operate stably for 100 hours.

[0082] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method for preparing an oxygen evolution electrode, characterized in that, It includes the following steps: Nickel nitrate, ferric nitrate, isopropanol, and glycerol are mixed to obtain a mixture; The current collector is placed in the mixture and ultrasonicated at room temperature and pressure. The frequency of the ultrasonication is 20kHz-80kHz and the duration of the ultrasonication is 2-10h.

2. The method for preparing the oxygen evolution electrode according to claim 1, characterized in that, The molar ratio of nickel nitrate to ferric nitrate is (3-5):1; And / or, the nickel nitrate is nickel nitrate hexahydrate; And / or, the ferric nitrate is ferric nitrate nonahydrate; And / or, the concentration of nickel nitrate is 80-240 mmol / L, based on the millimoles of nickel nitrate contained in the total volume of the mixture per liter; And / or, the concentration of the ferric nitrate is 30-50 mmol / L, based on the millimoles of the ferric nitrate contained in the total volume of the mixture per liter; And / or, the volume ratio of the isopropanol to the glycerol is (10-30):1; And / or, the ambient temperature is 15℃-40℃; And / or, the atmospheric pressure is 98 kPa-105 kPa.

3. The method for preparing the oxygen evolution electrode according to claim 2, characterized in that, The ambient temperature is 25℃; And / or, the atmospheric pressure is 101 kPa.

4. The method for preparing the oxygen evolution electrode according to claim 2, characterized in that, The molar ratio of nickel nitrate to ferric nitrate is 4:1; And / or, the concentration of nickel nitrate is 160 mmol / L, based on the millimoles of nickel nitrate contained in the total volume of the mixture per liter; And / or, the concentration of the ferric nitrate is 40 mmol / L, based on the millimoles of the ferric nitrate contained in the total volume of the mixture per liter; And / or, the amount of isopropanol used is 100-300 mL; And / or, the amount of glycerol used is 10-30 mL.

5. The method for preparing the oxygen evolution electrode according to claim 4, characterized in that, The amount of isopropanol used is 200 mL; And / or, the amount of glycerol used is 20 mL.

6. The method for preparing the oxygen evolution electrode according to claim 1, characterized in that, The current collector is a nickel mesh, nickel felt, or nickel foam; And / or, the size of the current collector is 5 cm × 5 cm; And / or, the pore density of the current collector is 75 ppi-110 ppi; And / or, the thickness of the current collector is 0.5-1.5 mm; And / or, the diameter of the pores in the oxygen evolution electrode is 100 μm-1000 μm.

7. The method for preparing the oxygen evolution electrode according to claim 6, characterized in that, The current collector is nickel foam; And / or, the thickness of the current collector is 1 mm.

8. The method for preparing the oxygen evolution electrode according to claim 1, characterized in that, The current collector is also cleaned before the ultrasound is performed.

9. The method for preparing the oxygen evolution electrode according to claim 8, characterized in that, The cleaning method involves ultrasonically placing the current collector in acetone, hydrochloric acid, deionized water, and anhydrous ethanol solutions, respectively, and then drying it.

10. The method for preparing the oxygen evolution electrode according to claim 9, characterized in that, In each solution, the sonication time is 2-10 min.

11. The method for preparing the oxygen evolution electrode according to claim 9, characterized in that, In each solution, the sonication time was 5 minutes.

12. The method for preparing the oxygen evolution electrode according to claim 1, characterized in that, The ultrasound was performed under a protective gas atmosphere; And / or, the frequency of the ultrasound is 40kHz-80kHz; And / or, the duration of the ultrasound is 2-6 hours.

13. The method for preparing the oxygen evolution electrode according to claim 12, characterized in that, The protective gas is argon or nitrogen.

14. The method for preparing the oxygen evolution electrode according to claim 1, characterized in that, After ultrasound, the current collector is rinsed and dried.

15. The method for preparing the oxygen evolution electrode according to claim 14, characterized in that, The rinsing solution used for rinsing is anhydrous ethanol; And / or, the drying is carried out in a vacuum oven; And / or, the drying temperature is 50-70°C; And / or, the drying time is 10-15 hours.

16. The method for preparing the oxygen evolution electrode according to claim 15, characterized in that, The drying temperature is 60°C; And / or, the drying time is 12 hours.

17. An oxygen evolution electrode, characterized in that, It is prepared using the method for preparing an oxygen evolution electrode as described in any one of claims 1 to 16.

18. The application of the oxygen evolution electrode as described in claim 17 in the electrolysis of water to produce hydrogen.

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