Alkaline water electrolyzer electrode, preparation method and application thereof

Abstract

The application relates to a basic water electrolysis cell electrode and a preparation method and application thereof, the electrode comprising a nickel base and a hydroxyl oxide catalyst covering the surface of the nickel base, the hydroxyl oxide catalyst being a NiFe x Co y (OH) z , a NiFe x Co y (OH) z covering the surface of the nickel base is prepared in situ through a one-step electrodeposition assisted by a magnetic field and is used for water electrolysis oxygen electrode, especially in a high-current-density alkaline electrolysis cell device. Compared with the prior art, the application reconstructs the electrode interface by utilizing a spin pinning effect, improves charge transfer kinetics, improves electrode oxygen evolution dynamic activity and rate, simultaneously regulates electrode catalytic material micro-morphology, increases electrode surface electrochemical activity area, reduces bubble detachment resistance, and realizes a high-activity basic water electrolysis cell electrode under a large-current-density condition.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis for hydrogen production, specifically to an alkaline water electrolyzer electrode, its preparation method, and its application. Background Technology

[0002] The excessive consumption of fossil fuels has led to massive pollutant emissions and an energy crisis, making the development of green hydrogen energy crucial for sustainable human development. Electrocatalytic water splitting for hydrogen production represents a clean and sustainable technology for converting renewable energy into green chemical fuels. Alkaline electrolyzers are a more mature and commercially viable technology, using a membrane to separate cathode and anode electrodes immersed in an alkaline solution. At the cathode, water splits to form hydrogen gas and release hydroxide anions, which pass through the membrane and recombine at the anode to form oxygen.

[0003] In electrochemical reactions, the electrode needs energy to overcome the activation barrier at the electrode-electrolyte interface. This energy is used to nucleate bubbles at active sites on the electrode surface. Once the bubbles reach a critical size, they detach from the electrode, thus enabling and maintaining the electrochemical hydrogen evolution or oxygen evolution reaction. However, current alkaline water electrolysis technologies utilize nickel-based electrocatalysts with slow kinetics, particularly the complex four-electron transfer process on the anode side, which generates significant overpotentials, increasing production costs and decreasing hydrogen production efficiency. Furthermore, numerous studies indicate that the generated bubbles can adhere to the electrode surface due to adhesion between the electrode and the bubbles, reducing the electrochemical active area, limiting current density, causing voltage drops, generating unnecessary heat, and resulting in uneven current distribution. Electrocatalytic properties are related to the inherent properties of the materials. To meet industrial demands for efficient hydrogen production, researchers have focused on improving the oxygen evolution activity of nickel electrocatalysts and enhancing bubble desorption to reduce electrode mass transport, ultimately aiming to achieve high-efficiency alkaline water electrolyzers.

[0004] To address the aforementioned issues, recent research has made significant progress in enhancing electrochemical activity and accelerating bubble removal by controlling the structure, microstructure, crystal structure, and electrode composition of nickel electrodes. However, as alkaline electrolyzers develop towards higher operating current densities, maintaining both efficient oxygen evolution kinetics and rapid bubble removal capabilities for nickel electrodes remains a challenge. Summary of the Invention

[0005] The purpose of this invention is to provide an alkaline water electrolyzer electrode, its preparation method, and its application, thereby improving the electrode activity under high current density in alkaline electrolyzers.

[0006] The objective of this invention can be achieved through the following technical solution: an alkaline water electrolyzer electrode, comprising a nickel substrate and a hydroxyl oxide catalyst covering the surface of the nickel substrate, wherein the hydroxyl oxide catalyst is NiFe with a microscopic layered morphology.x Co y (OH) z .

[0007] The hydroxyl oxide catalyst described herein can generate a spin pinning effect after being magnetized or under the influence of an external magnetic field.

[0008] Preferably, the nickel substrate is one of foamed nickel, three-dimensional nickel-iron alloy, nickel-cobalt alloy, and nickel-iron-cobalt alloy.

[0009] A method for preparing the electrode of the above-mentioned alkaline water electrolyzer involves in-situ preparation of NiFe by one-step electrodeposition assisted by a magnetic field. x Co y (OH) z It covers the surface of a nickel substrate.

[0010] Preferably, the preparation method of the above-mentioned alkaline water electrolyzer electrode specifically includes the following steps: (1) The nickel substrate was placed in hydrochloric acid solution for ultrasonic cleaning, then cleaned with ethanol and aqueous solution in sequence, and after being thoroughly dried, oxygen plasma treatment was used to remove impurities and introduce surface defects on the nickel substrate surface. (2) A certain amount of nickel chloride hexahydrate, ferric chloride tetrahydrate, cobalt chloride hexahydrate and potassium sodium tartrate were dissolved in deionized water to form an electrolyte. Electrochemical deposition was carried out using a three-electrode system under an external magnetic field and a certain voltage. The treated nickel substrate was used as the working electrode, the platinum mesh was used as the counter electrode, and Ag / AgCl was used as the reference electrode. After deposition, the electrode was rinsed with deionized water to obtain an alkaline electrode with spin pinning effect.

[0011] More preferably, the concentration of the hydrochloric acid solution in step (1) is 0.5~2 mol / L, the ultrasonic duration is 5~20 min, and the plasma treatment is 6~12 min.

[0012] More preferably, in the electrolyte of step (2), the atomic ratio of nickel:iron:cobalt is (0.5~0.8):(0.2~0.1):(0.3~0.1), the content of transition metals in the electrolyte is 0.1~0.2 mol / L, and the content of potassium sodium tartrate is 0.4~0.8 mol / L.

[0013] More preferably, the direction of the external magnetic field in step (2) is at 45 degrees to the plane of the nickel substrate, and the magnetic field strength is 20~60 mT.

[0014] More preferably, the electrochemical deposition voltage in step (2) is 0.8~1.2 V (vs. Ag / AgCl), and the deposition time is 10~40 min.

[0015] More preferably, after electrochemical deposition in step (2), the sample is rinsed with deionized water 2 to 3 times.

[0016] An application of the above-mentioned alkaline water electrolyzer electrode is to use the electrode as a water electrolysis oxygen electrode.

[0017] More preferably, the electrode is used in a high current density alkaline electrolysis cell.

[0018] This invention utilizes a magnetic field-assisted one-step electrodeposition to prepare NiFe with a stacked morphology exhibiting a spin pinning effect in situ. x Co y (OH) z It is coated on the surface of a nickel substrate. By reconstructing the electrode interface using the spin pinning effect, the charge transfer kinetics are improved, the oxygen evolution kinetic activity and rate of the electrode are enhanced, and the microstructure of the electrode catalytic material is controlled, increasing the electrochemical active area of ​​the electrode surface and reducing the bubble detachment resistance, thus realizing a highly active alkaline water electrolyzer electrode under high current density conditions.

[0019] Compared with the prior art, the present invention has the following advantages: 1. The alkaline water electrolyzer electrode provided by this invention utilizes a magnetic field-assisted one-step electrodeposition to prepare NiFe in situ. x Co y (OH) z The hydroxyl oxide layer utilizes the spin pinning effect generated by the magnetic moment exchange of paramagnetic hydroxyl oxide atoms to reconstruct the electrode interface, optimize the interface electronic structure and improve the spin polarization of the oxygen evolution process, thereby increasing the oxygen molecule generation rate and realizing the intrinsic oxygen evolution activity of the electrode catalytic material. 2. This invention modulates NiFe x Co y (OH) z The nanoscale microstructure can not only increase the electrochemical active area, but also help to reduce the size of the bubbles to promote the rapid transport and release of the bubbles, thereby improving the electrode activity under high current density in the alkaline electrolyzer. 3. The alkaline water electrolyzer electrode provided by the present invention comprises a layer of NiFe with a micro-layered morphology exhibiting a spin pinning effect, coated on a three-dimensional nickel substrate. x Co y (OH) z The electrode interface structure was optimized, the charge transfer kinetics were improved, and the oxygen evolution kinetic activity and rate of the electrode were enhanced. At the same time, the microstructure of the electrode catalytic material was controlled, the electrochemical active area of ​​the electrode surface was increased, and the bubble detachment resistance was reduced, thus realizing a highly active alkaline water electrolyzer electrode under high current density conditions. Attached Figure Description

[0020] Figure 1 The X-ray diffraction spectrum of the electrode in Example 3; Figure 2 X-ray photoelectron spectroscopy of the electrode in Example 3; Figure 3 The image is a 5000x scanning electron microscope image of the electrode in Example 3. Figure 4 The image is a 10,000x scanning electron microscope image of the electrode in Example 3. Figure 5 The polarization curves of the electrodes in Examples 1-3 are shown. Figure 6 For the electrodes of Examples 1-3 at 0.1 A cm -2 and 0.8 A cm -2 The corresponding electrolytic cell voltage; Figure 7 The impedance versus time diagrams for electrodes in Examples 1-3 are shown. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The following embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following embodiments.

[0022] Example 1 (1) Cut the nickel foam into 3×3 cm pieces. 2 To determine the size, the cut nickel substrate was placed in 30 ml of hydrochloric acid solution (1M) and ultrasonically cleaned for 10 min. Then it was cleaned twice with ethanol and aqueous solution in sequence. After being thoroughly dried in a 60-degree oven, it was treated with oxygen plasma for 10 min to remove impurities and introduce surface defects on the nickel substrate surface. (2) 1.68 g nickel chloride hexahydrate, 0.36 g ferric chloride tetrahydrate, 0.26 g cobalt chloride hexahydrate and 0.88 g potassium sodium tartrate were dissolved in 100 ml of deionized water to form an electrolyte. Electrochemical deposition was carried out using a three-electrode system at 1.0 V (vs. Ag / AgCl). The treated nickel substrate was used as the working electrode, the platinum mesh was used as the counter electrode, and Ag / AgCl was used as the reference electrode. The deposition time was 30 min. After deposition, the electrode was rinsed three times with deionized water to obtain an alkaline electrode.

[0023] Example 2 (1) Cut the nickel foam into 3×3 cm pieces. 2To determine the size, the cut nickel substrate was placed in 30 ml of hydrochloric acid solution (1M) and ultrasonically cleaned for 10 min. Then it was cleaned twice with ethanol and aqueous solution in sequence. After being thoroughly dried in a 60-degree oven, it was treated with oxygen plasma for 10 min to remove impurities and introduce surface defects on the nickel substrate surface. (2) 1.68 g nickel chloride hexahydrate, 0.36 g ferric chloride tetrahydrate, 0.26 g cobalt chloride hexahydrate and 0.88 g potassium sodium tartrate were dissolved in 100 ml of deionized water to form an electrolyte. Electrochemical deposition was carried out using a three-electrode system under an external magnetic field of 30 mT at 1.0 V (vs. Ag / AgCl). The treated nickel substrate was used as the working electrode, the platinum mesh was used as the counter electrode, and Ag / AgCl was used as the reference electrode. The direction of the external magnetic field was 45 degrees to the plane of the nickel substrate. The deposition time was 30 min. After deposition, the electrode was rinsed three times with deionized water to obtain an alkaline electrode.

[0024] Example 3 (1) Cut the nickel foam into 3×3 cm pieces. 2 To determine the size, the cut nickel substrate was placed in 30 ml of hydrochloric acid solution (1M) and ultrasonically cleaned for 10 min. Then it was cleaned twice with ethanol and aqueous solution in sequence. After being thoroughly dried in a 60-degree oven, it was treated with oxygen plasma for 10 min to remove impurities and introduce surface defects on the nickel substrate surface. (2) 1.68 g nickel chloride hexahydrate, 0.36 g ferric chloride tetrahydrate, 0.26 g cobalt chloride hexahydrate and 0.88 g potassium sodium tartrate were dissolved in 100 ml of deionized water to form an electrolyte. Electrochemical deposition was carried out using a three-electrode system under an external magnetic field of 60 mT at 1.0 V (vs. Ag / AgCl). The treated nickel substrate was used as the working electrode, the platinum mesh was used as the counter electrode, and Ag / AgCl was used as the reference electrode. The direction of the external magnetic field was 45 degrees to the plane of the nickel substrate. The deposition time was 30 min. After deposition, the electrode was rinsed three times with deionized water to obtain an alkaline electrode.

[0025] Figure 1 The X-ray diffraction spectrum of the electrode prepared in Example 3 shows diffraction angles of 11.1°, 22.4°, 34.2°, 60.7°, and 71.2°, corresponding to NiFe3, respectively. x Co y (OH) z The (003), (006), (012), (113) and (119) crystal planes; Figure 2 The X-ray photoelectron spectroscopy of the electrode prepared in Example 3 shows that the prepared NiFe x Co y (OH) zThe electrode mainly contains elements such as Ni, Fe, Co, and O, with C possibly being caused by contaminants. Figures 3-4 The scanning electron microscope images (a) at 5000x and (b) at 10000x magnification of the electrode in Example 3 show the electrodeposited NiFe. x Co y (OH) z It exhibits a layered structure morphology, which can effectively increase the contact area with the electrolyte, increase the electrochemical active area, and may also promote the effective detachment of bubbles generated on the electrode surface.

[0026] The prepared electrode was placed as an oxygen evolution electrode in a single electrolytic cell fixture of an alkaline water electrolyzer for testing. Figures 5-6 The polarization curves of the electrodes in Examples 1-3 at a reaction temperature of 60 °C are shown in (a) and (b) at 0.1 A cm⁻¹. -2 and 0.8 A cm -2 The corresponding electrolytic cell voltage. Example 1: Electrochemical deposition of NiFe x Co y (OH) z No external magnetic field was applied during the process, and the current density was 0.1 A cm⁻¹. -2 and 0.8 A cm -2 The corresponding electrolytic cell voltages were 1.631 V and 2.137 V, respectively; Example 2 involved the electrochemical deposition of NiFe. x Co y (OH) z An external magnetic field of 30 mT was applied during the process, with a current density of 0.1 A cm⁻¹. -2 and 0.8 Acm -2 The corresponding electrolytic cell voltages were 1.609 V and 1.975 V, respectively; Example 3 involved the electrochemical deposition of NiFe. x Co y (OH) z An external magnetic field of 60 mT was applied during the process, with a current density of 0.1 A cm⁻¹. -2 and 0.8 A cm -2 The corresponding electrolytic cell voltages were 1.583 V and 1.906 V, respectively, indicating that NiFe prepared under an external magnetic field of 60 mT... x Co y (OH) z NiFe exhibits optimal electrochemical oxygen evolution performance and is prepared under an external magnetic field. x Co y (OH) z By employing a spin pinning effect, the electron spin state during the oxygen evolution reaction is controlled, thus optimizing the intrinsic activity of the electrode material.

[0027] Figure 7 The figures show the impedance versus time curves of the electrodes prepared in Examples 1-3, tested in a single-cell fixture of an alkaline water electrolyzer. The impedance curves of Examples 1 and 2 are sawtooth-shaped, while the impedance curve of the electrode in Example 3 is relatively smooth. The increase in impedance is caused by oxygen bubbles covering the electrode surface, which interrupts the supply of alkali to the electrode. As the large bubbles detach from the surface, the impedance decreases rapidly. The results indicate that the prepared NiFe x Co y (OH) z The layered structure of the electrodes can promote the growth and separation of bubbles more quickly.

[0028] This invention optimizes the spin-electronic structure of the electrode catalytic material, reduces the bonding energy of oxygen intermediates, improves charge transfer kinetics, and enhances the oxygen evolution kinetic activity of the electrode. At the same time, it regulates the microstructure of the electrode catalytic material, increases the electrochemical active area on the electrode surface, and reduces the resistance to bubble detachment, thereby achieving a highly active alkaline water electrolyzer electrode under high current density conditions.

[0029] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. An electrode for an alkaline water electrolyzer, characterized in that, Includes a nickel substrate and a catalyst covering the surface of the nickel substrate, wherein the catalyst is NiFe with a microstructure of stacked layers. x Co y (OH) z ; The preparation method of the alkaline water electrolyzer electrode specifically includes the following steps: (1) The nickel substrate was placed in hydrochloric acid solution for ultrasonic cleaning, then cleaned with ethanol and water in sequence, and after being thoroughly dried, oxygen plasma treatment was used to remove impurities and introduce surface defects on the nickel substrate surface. (2) A certain amount of nickel chloride hexahydrate, ferric chloride tetrahydrate, cobalt chloride hexahydrate and potassium sodium tartrate are dissolved in deionized water to form an electrolyte. Electrochemical deposition is carried out using a three-electrode system under an external magnetic field and a certain voltage. The treated nickel substrate is used as the working electrode, the platinum mesh is used as the counter electrode, and Ag / AgCl is used as the reference electrode. After deposition, the electrode is rinsed with deionized water to obtain the alkaline water electrolysis cell electrode. In the electrolyte described in step (2), the atomic ratio of nickel:iron:cobalt is (0.5~0.8):(0.1~0.2):(0.1~0.3), the content of transition metals in the electrolyte is 0.1~0.2 mol / L, and the content of potassium sodium tartrate is 0.4~0.8 mol / L.

2. The alkaline water electrolysis cell electrode according to claim 1, characterized in that, The nickel substrate is one of foamed nickel, three-dimensional nickel-iron alloy, nickel-cobalt alloy, and nickel-iron-cobalt alloy.

3. The alkaline water electrolysis cell electrode according to claim 1, characterized in that, In-situ preparation of NiFe by magnetic field-assisted one-step electrodeposition x Co y (OH) z It is coated on the surface of a nickel substrate.

4. The alkaline water electrolyzer electrode according to claim 3, characterized in that, The concentration of the hydrochloric acid solution in step (1) is 0.5~2 mol / L, the ultrasonic treatment time is 5~20 min, and the plasma treatment time is 6~12 min.

5. The alkaline water electrolyzer electrode according to claim 3, characterized in that, The direction of the external magnetic field in step (2) is at 45 degrees to the plane of the nickel substrate, and the magnetic field strength is 20~60 mT.

6. The alkaline water electrolyzer electrode according to claim 3, characterized in that, The electrochemical deposition voltage in step (2) is 0.8~1.2 V, and the deposition time is 10~40 min.

7. An application of an alkaline water electrolyzer electrode as described in any one of claims 1-6, characterized in that, The electrode described above is used as an oxygen electrode for water electrolysis.

8. The application of the alkaline water electrolyzer electrode according to claim 7, characterized in that, The electrode is used in a high-current-density alkaline electrolysis cell.

Images