An alkaline water electrolysis oxygen evolution electrode and its preparation method and application

Abstract

The present invention relates to an alkaline water electrolysis oxygen evolution electrode and its preparation method and application. The preparation method comprises: in a two-electrode system, using a nickel-iron metal salt aqueous solution as an electroplating solution, a commercial nickel mesh as an anode, and an electro-etched nickel mesh as a cathode; energizing the electrodes so that the surface of the commercial nickel mesh at the anode undergoes electro-etching, and the surface of the electro-etched nickel mesh at the cathode undergoes electrodeposition; removing the electroded cathode as a finished electrode and replacing it with a new commercial nickel mesh, while leaving the anode unchanged; then reversing the current direction, reversing the electrodes, and repeating the electro-etching and electrodeposition cycles, thereby achieving continuous production of the alkaline water electrolysis oxygen evolution electrode. Compared with the prior art, the preparation method of the present invention is far superior to existing electrode preparation technologies in terms of preparation simplicity, economy, catalytic performance, and service life, greatly improving the economic benefits of industrial water electrolysis.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production by electrolysis of water, and in particular to an alkaline water electrolysis oxygen evolution electrode and a preparation method and application thereof. Background Art

[0002] As the consumption of fossil energy becomes increasingly serious, countries around the world are committed to finding a new type of alternative energy to alleviate the environmental pollution problems caused by the consumption of fossil energy. Hydrogen energy has gradually become the most promising energy option due to its high energy density and environmental friendliness. The rapid development of my country's wind power and photovoltaic industries in recent years has further stimulated researchers' attention to hydrogen energy. However, in the process of hydrogen production by water electrolysis, the oxygen evolution reaction (OER) has a high overpotential and slow kinetics, which has always been a bottleneck limiting the energy conversion efficiency of the entire water electrolysis system and limiting the economic benefits of hydrogen production by water electrolysis. Reasonable catalytic electrode design can greatly reduce energy loss, improve the efficiency of water electrolysis reaction, and promote the development of the hydrogen energy industry.

[0003] Electrodeposition technology involves applying an electric current to both ends of an electrode, causing a reduction reaction at the cathode, reducing metal cations in solution to metal deposits on the electrode surface. As a simple and mature catalyst preparation method, it has long been favored in industrial applications. However, catalysts prepared using electrodeposition technology also have a problem: because the catalyst is attached to the electrode surface, it can easily fall off after prolonged use or external impact, especially on smooth electrode surfaces.

[0004] However, the raw materials used for industrial electrodes are smooth nickel mesh or other metal plates, which are not conducive to the deposition and adhesion of catalysts. Therefore, an additional step is required to roughen the electrode surface. Common methods for roughening electrodes, such as chemical etching, physical scratching, or structural changes, undoubtedly increase the number of electrode preparation steps and the complexity of the system, inevitably leading to an increase in overall costs, which is detrimental to the production of electrodes for industrial water electrolysis.

[0005] In view of the difficulties faced by existing electrodes under industrial water electrolysis conditions, there is an urgent need to design a new electrode preparation method that is easy to produce industrially and facilitates the attachment of electrodeposition catalysts. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the existing alkaline water electrolysis electrode preparation process, that is, the catalyst obtained by the electrodeposition method has poor adhesion to the electrode surface and the process of roughening the electrode surface is complicated.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] The first aspect of the present invention provides a method for preparing a high-efficiency alkaline water electrolysis oxygen evolution electrode, comprising the following steps:

[0009] A) In a two-electrode system, an aqueous solution of nickel-iron metal salt is used as the electroplating solution, a commercial nickel mesh is used as the anode, and an electro-etched nickel mesh is used as the cathode;

[0010] B) energizing the electrodes so that the commercial nickel mesh surface of the anode is electro-etched and the surface of the nickel mesh that has been electro-etched at the cathode is electro-deposited, wherein after the electro-etching, the anode obtains the electro-etched nickel mesh and the cathode obtains the nickel mesh having a composite nickel-iron hydroxide deposition layer on the electro-etched surface;

[0011] C) The cathode after electrodeposition in step B) is removed as the finished electrode and replaced with a new commercial nickel mesh, while the anode remains unchanged. The current direction is then reversed, and the electrodes are reversed, and electro-etching and electrodeposition are repeated. This cycle is repeated to achieve continuous production of alkaline water electrolysis oxygen evolution electrodes.

[0012] Furthermore, the commercial nickel mesh is pretreated before use, and the pretreatment process is as follows: the commercial nickel mesh is first ultrasonically treated in dilute hydrochloric acid, then ultrasonically treated in anhydrous ethanol, then ultrasonically treated in deionized water, and finally naturally dried.

[0013] Furthermore, the nickel wire diameter of the pretreated nickel mesh is 50 to 300 μm, and the mesh number of the nickel mesh is 50 to 400 meshes.

[0014] Furthermore, in step A), in the electroplating solution, the concentration of nickel chloride is 0.6-1.4 mol / L, the concentration of ferrous chloride is 0.2-0.8 mol / L, and the concentration of ammonium chloride is 1.6-2.4 mol / L.

[0015] Furthermore, in step B), the current density of the electro-etching and electro-deposition is 20-40 mA / cm 2 , time is 8 to 12 minutes, temperature is 20 to 30℃.

[0016] Furthermore, in step B), after the electrodeposition, the process further comprises: washing the composite material after cathode electrodeposition with deionized water, then washing with anhydrous ethanol, and then drying naturally.

[0017] Furthermore, in step B), the anode and cathode react simultaneously, the anode undergoes an electro-etching reaction to roughen the surface of the new nickel mesh, and the cathode undergoes an electro-deposition reaction to deposit nickel-iron catalyst on the surface electro-etched in the previous round of reaction.

[0018] Furthermore, the cathode and anode after the electrode replacement and reversal in step C) are directly used in step B), so that new electrodeposition is performed on the electro-etched surface, and a new electrode is electro-etched at the other pole at the same time.

[0019] A second aspect of the present invention provides an alkaline water electrolysis oxygen evolution electrode prepared by the above method, wherein the alkaline water electrolysis oxygen evolution electrode comprises:

[0020] Nickel mesh base material;

[0021] An electro-etching layer composited on the surface of a nickel mesh base material;

[0022] A nickel-iron hydroxide deposition layer is composited on the electro-etching layer.

[0023] A third aspect of the present invention provides an application of the above alkaline water electrolysis oxygen evolution electrode in hydrogen production by water electrolysis.

[0024] The core mechanism of the present invention is:

[0025] The purpose of the present invention is to overcome the shortcomings of poor adhesion of the catalyst obtained by the electrodeposition method to the electrode surface and the complex process of roughening the electrode surface during the preparation of alkaline water electrolysis electrodes. In the present invention, the above-mentioned two problems can be solved at the same time through step B). In this step, the anode and the cathode react simultaneously, the anode undergoes an electro-etching reaction, roughening the surface of the new nickel mesh; the cathode undergoes an electro-deposition reaction, and the nickel-iron catalyst is deposited on the surface electro-etched in the previous round of reaction. After the electrode is reversed in step C), a new electro-deposition can be directly performed on the surface electro-etched in step B), and a new electrode can be electro-etched at the other pole at the same time. Therefore, the preparation method of the alkaline water electrolysis oxygen evolution electrode provided by the present invention is an electrode material with simple process, low requirements on production equipment, low preparation cost and stable catalyst adhesion.

[0026] Compared with the prior art, the present invention has the following technical advantages:

[0027] 1) This technical solution can achieve stable adhesion of the electrodeposited catalyst. By electro-etching the nickel mesh, the originally smooth surface of the nickel mesh becomes rough, which is more conducive to the fixation of the electrodeposited catalyst on its surface.

[0028] 2) The preparation process of this technical solution is efficient and convenient. During the electrode preparation process, the anode is electro-etched and the cathode is electro-deposited, and all the processes required for this preparation method are completed at the same time.

[0029] 3) This technical solution significantly saves production and preparation costs. Only one system is needed to complete the electro-etching and electro-deposition processes simultaneously. The nickel metal ions lost in the electro-etching reaction will enter the electroplating solution and become the raw materials for electro-deposition. No additional nickel ions need to be added during the entire process.

[0030] 4) Therefore, the electrode preparation method proposed in the present invention is very suitable for industrial mass production. Whether in terms of preparation simplicity, economy or catalytic performance and service life, it is far superior to the use of existing electrode preparation technology in industrial electrolysis of water, greatly improving the economic benefits of industrial electrolysis of water. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the NM microscope image after preprocessing in Example 1 of the present invention;

[0032] Figure 2 This is the NMetch microscope image in Example 1 of the present invention;

[0033] Figure 3 This is a microscope image of nickel-iron hydroxide NiFeOxHy / NMetch electrodeposited on an electro-etched nickel mesh in Example 1 of the present invention;

[0034] Figure 4 This is a microscope image of nickel-iron hydroxide NiFeOxHy / NM electrodeposited on a commercial nickel mesh in Application Example 1 of the present invention.

[0035] Figure 5 This is the current-voltage scanning curve of the oxygen evolution reaction in Application Example 1 of the present invention. DETAILED DESCRIPTION

[0036] The present invention provides an alkaline water electrolysis oxygen evolution electrode that is easy to prepare, comprising:

[0037] Nickel mesh base material;

[0038] an electro-etched layer on the surface of the nickel mesh base material;

[0039] A nickel-iron hydroxide deposition layer is composited on the electro-etching layer.

[0040] Specifically, they include:

[0041] Nickel mesh base material;

[0042] An electro-etched layer formed on the surface of the nickel mesh base material by an electro-etching method;

[0043] A nickel iron hydroxide deposition layer is composited on the electro-etching layer by an electro-deposition method.

[0044] The present invention also provides a simple method for preparing the alkaline water electrolysis oxygen evolution electrode as described above, comprising the following steps:

[0045] A) In a two-electrode system, an aqueous solution of nickel-iron metal salt is used as the electroplating solution, a commercial nickel mesh is used as the anode, and an electro-etched nickel mesh is used as the cathode;

[0046] B) Power is applied to the electrodes. Electroetching occurs on the surface of the commercial nickel mesh at the anode, while electrodeposition occurs on the previously electroetched nickel mesh at the cathode. Thus, the anode receives the electroetched nickel mesh, while the cathode receives the nickel mesh with a deposited nickel-iron hydroxide layer on the electroetched surface.

[0047] C) Remove the nickel mesh prepared as the cathode in step B) and replace it with a new commercial nickel mesh. Keep the nickel mesh electro-etched as the anode in step B) in place. Reverse the direction of the current, reversing the electrodes and repeating step A), repeating the cycle.

[0048] In certain embodiments of the present invention, the commercial nickel mesh is a pretreated nickel mesh. The pretreated nickel mesh is prepared according to the following method:

[0049] The nickel mesh was ultrasonically treated in dilute hydrochloric acid to remove surface oxides, then ultrasonically treated in anhydrous ethanol to remove surface hydrochloric acid and organic matter, and finally ultrasonically treated in deionized water to remove other residual impurities on the surface.

[0050] In certain embodiments of the present invention, the concentration of dilute hydrochloric acid is 0.5 to 1.2 mol / L, and specifically 1 mol / L. The ultrasonic treatment time is 15 minutes.

[0051] In the present invention, a two-electrode system uses a nickel-iron metal salt as the electroplating solution, a commercial nickel mesh is used as the anode, and an electro-etched nickel mesh is used as the cathode. Electro-etching occurs on the surface of the commercial nickel mesh at the anode, while electrodeposition occurs on the surface of the electro-etched nickel mesh at the cathode. The anode thus produces the electro-etched nickel mesh, while the cathode produces the nickel mesh with a deposited nickel-iron hydroxide layer on the electro-etched surface.

[0052] In certain embodiments of the present invention, a nickel-iron metal salt electroplating solution includes nickel chloride, ferrous chloride, ammonium chloride, and deionized water. In the nickel-iron metal salt electroplating solution, the concentration of nickel chloride is 0.6 to 1.4 mol / L, the concentration of ferrous chloride is 0.2 to 0.8 mol / L, and the concentration of ammonium chloride is 1.6 to 2.4 mol / L. Specifically, the concentration of nickel chloride, ferrous chloride, and ammonium chloride in the nickel-iron metal salt electroplating solution may be 1 mol / L, 0.5 mol / L, and 2 mol / L.

[0053] In certain embodiments of the present invention, the electrodeposition is carried out in a deposition tank. The current density of the electro-etching (anode) / electro-deposition (cathode) is 20-40 mA / cm 2 , time is 8 to 12 minutes, temperature is 20 to 30 ° C; specifically, the current density of electro-etching (anode) / electro-deposition (cathode) can be 30 mA / cm 2 , the electrodeposition time can be 10 min, and the plating solution temperature can be 25°C.

[0054] In certain embodiments of the present invention, after electrodeposition, washing and drying are further included. Specifically, the electrodeposited composite material is rinsed with deionized water, then rinsed with anhydrous ethanol, and then naturally dried. The number of rinses may be 3 to 5, specifically 3. Each rinse lasts 10 to 30 seconds, specifically 20 seconds. The rinse flow rate should be gentle so as not to damage the electrodeposited structure.

[0055] The present invention also provides an application of a simple method for preparing an alkaline water electrolysis oxygen evolution electrode in water electrolysis hydrogen production; specifically, the present invention also provides an application of the above-mentioned simple method for preparing an alkaline water electrolysis oxygen evolution electrode to prepare a water electrolysis hydrogen production catalyst.

[0056] The present invention uses a nickel mesh as a base material; an electro-etching method is used to form a rough nickel mesh surface, which has a larger surface area and is more conducive to the adhesion of a catalyst; an electrodeposition method is used to form a nickel-iron hydroxide deposition layer on the electro-etched nickel mesh base surface, thereby preparing an alkaline water electrolysis oxygen evolution electrode catalyst material with high efficient catalytic performance and good adhesion performance.

[0057] The present invention uses a synchronous electro-etching / electro-deposition reaction process, which avoids the separate use of two electro-etching and electro-deposition devices, simplifies system complexity, reduces production time and cost, greatly improves production efficiency, and is suitable for industrial large-scale production.

[0058] The present invention has no particular restrictions on the sources of the raw materials used above, and they can be generally commercially available. The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. Any features such as preparation methods, materials, structures, or composition ratios not explicitly described in this technical solution are considered to be common technical features disclosed in the prior art.

[0059] In order to further illustrate the present invention, a simple method for preparing an alkaline water electrolysis oxygen evolution electrode and its application provided by the present invention are described in detail below in conjunction with examples, but it should not be understood as limiting the scope of protection of the present invention.

[0060] Example 1

[0061] The preparation method of the catalyst for hydrogen production by alkaline water electrolysis in this embodiment comprises the following steps:

[0062] 1) Pretreatment of nickel mesh:

[0063] The nickel mesh was ultrasonically treated in 1 mol / L dilute hydrochloric acid to remove surface oxides, then ultrasonically treated in anhydrous ethanol to remove surface hydrochloric acid and organic matter, and finally ultrasonically treated in deionized water to remove other residual impurities on the surface, obtaining a pretreated nickel mesh (named NM);

[0064] 2) Electroetching (anode) / electrodeposition (cathode) of nickel mesh:

[0065] The nickel-iron metal salt electroplating solution comprises nickel chloride, ferrous chloride, ammonium chloride and deionized water; in the nickel-iron metal salt electroplating solution, the concentration of nickel chloride is 1 mol / L, the concentration of ferrous chloride is 0.5 mol / L, and the concentration of ammonium chloride is 2 mol / L.

[0066] In the two-electrode system, the anode is a commercial nickel mesh, the cathode is a nickel mesh that was electro-etched in the previous round of reaction, and the deposition tank is filled with the nickel-iron metal salt electroplating solution prepared in the above steps. The current density of the electro-etching (anode) / electro-deposition (cathode) is 30 mA / cm 2 The time is 10min and the temperature is 25℃. The composite material is taken out from the deposition tank, cleaned with deionized water and anhydrous ethanol, and dried naturally. The anode is the nickel mesh (named NM etch ), the cathode obtains a nickel iron hydroxide deposition layer attached to the electro-etched nickel mesh (named NiFeO x H y / NM etch ).

[0067] Figure 1 This is the NM microscope image after preprocessing in Example 1 of the present invention;

[0068] Figure 2 NM in Example 1 of the present invention etch Microscope images;

[0069] Depend on Figure 1 and Figure 2 It can be seen that after the electro-etching process, Figure 1 Compared with the smooth surface of the nickel mesh, the electro-etching process makes the surface of the nickel mesh rough, increasing the surface area of ​​the nickel mesh and making it easier for subsequent deposition materials to adhere.

[0070] Figure 3 Electrodeposition of nickel iron hydroxide NiFeO on the electroetched nickel mesh in Example 1 of the present invention x H y / NM etch Microscope images of

[0071] Figure 4 The nickel iron hydroxide NiFeO is deposited on the commercial nickel mesh in Application Example 1 of the present invention. x H y / Microscope images of NM.

[0072] Depend on Figure 3 and Figure 4The nickel-iron hydroxide catalyst deposited on the electro-etched nickel mesh exhibits uniform distribution and good morphological characteristics. However, on the commercial nickel mesh that has not been electro-etched, the nickel-iron hydroxide deposit is weak and has an uneven structural distribution. This suggests that the roughening of the smooth nickel mesh surface by electro-etching results in better morphological and structural characteristics for the catalyst deposited on this surface.

[0073] Application Example 1

[0074] This application example uses a standard three-electrode system with mercury / mercury oxide (Hg / HgO) as the reference electrode and a 2×2 cm 2 The platinum sheet is the counter electrode, 1*1cm 2 The NiFeO electrode prepared in Example 1 x H y / NM etch The electrochemical test was carried out on a Corrtest electrochemical workstation with 1 mol / L KOH solution as the working electrode and the test temperature controlled at 25°C for oxygen evolution reaction.

[0075] A control group 1 was set up, using the NM in Example 1 as the working electrode, and the rest of the operations were the same as the above steps;

[0076] Set up control group 2 and use NiFeO x H y / NM was used as the working electrode, and the rest of the operations were the same as the above steps.

[0077] Preparation of the working electrode in control group 2: In the preparation process of Example 1, a commercial nickel mesh that had only been pretreated was used as the working electrode instead of an electro-etched nickel mesh during the electrodeposition process. The remaining preparation steps were exactly the same, and a nickel iron hydroxide deposition layer (named NiFeO x H y / NM).

[0078] Linear scanning Fu'an curve test: The scanning speed is 5mV / s, and the electrode potential is 90% iR compensated and converted into the electrode potential relative to the reversible hydrogen potential (RHE). The calculation formula is shown in formula (*):

[0079] Overpotential (V) = electrode potential + 0.059 × pH + Hg / HgO electrode potential - 1.23 (*)

[0080] In the above formula (*), pH is the pH value of the electrolyte.

[0081] Figure 5The current-voltage scanning curve of the oxygen evolution reaction in Application Example 1 of the present invention shows that the composite electrode obtained by electrodepositing nickel iron hydroxide on the surface of a commercial nickel mesh that has not been electroetched has poor OER performance, which is only slightly better than the original nickel mesh material; while the composite electrode obtained by electrodepositing nickel iron hydroxide on the surface of an electroetched nickel mesh has greatly improved OER performance at both overpotential and high current.

[0082] Therefore, in the present invention, the originally smooth nickel mesh is roughened through electro-etching. This surface structure increases the contact area of ​​the catalyst, allowing it to firmly adhere to the electrode substrate, resulting in better conductivity and catalyst durability. The preparation method of the present invention, while the working electrode undergoes electrodeposition, also undergoes electro-etching of the counter electrode for the next reaction. This preparation method greatly improves production efficiency and effectively reduces production costs, making it very suitable for preparing electrodes for industrial water electrolysis.

[0083] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. 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 present invention, should be within the scope of protection of the present invention.

Claims

1. A method for preparing a high-efficiency alkaline water electrolysis oxygen evolution electrode, characterized in that: The following steps are involved: A) In a two-electrode system, an aqueous solution of nickel-iron metal salt is used as the electroplating solution, a commercial nickel mesh is used as the anode, and an electro-etched nickel mesh is used as the cathode. B) energizing the electrodes to cause electro-etching of the commercial nickel mesh surface at the anode and electro-deposition of the electro-etched nickel mesh surface at the cathode. After electro-etching, the anode obtains the electro-etched nickel mesh, and the cathode obtains the nickel mesh with a nickel-iron hydroxide deposited layer on the electro-etched surface. C) The cathode after electrodeposition in step B) is removed as the finished electrode and replaced with a new commercial nickel mesh, while the anode remains unchanged. The current direction is then reversed, and the electrodes are reversed. Electro-etching and electrodeposition are repeated, and this cycle is repeated to achieve continuous production of alkaline water electrolysis oxygen evolution electrodes; In step A), in the electroplating solution, the concentration of nickel chloride is 0.6-1.4 mol / L, the concentration of ferrous chloride is 0.2-0.8 mol / L, and the concentration of ammonium chloride is 1.6-2.4 mol / L.

2. The method for preparing a high-efficiency alkaline water electrolysis oxygen evolution electrode according to claim 1, wherein: The commercial nickel mesh is pretreated before use. The pretreatment process is as follows: the commercial nickel mesh is first ultrasonically treated in dilute hydrochloric acid, then ultrasonically treated in anhydrous ethanol, then ultrasonically treated in deionized water, and finally naturally dried.

3. The method for preparing a high-efficiency alkaline water electrolysis oxygen evolution electrode according to claim 2, wherein: The nickel wire diameter of the pretreated nickel mesh is 50-300 μm, and the mesh number of the nickel mesh is 50-400 meshes.

4. The method for preparing a high-efficiency alkaline water electrolysis oxygen evolution electrode according to claim 1, wherein: In step B), the current density of the electro-etching and electro-deposition is 20-40 mA / cm 2 , time is 8~12min, temperature is 20~30℃.

5. The method for preparing a high-efficiency alkaline water electrolysis oxygen evolution electrode according to claim 1, characterized in that: In step B), after the electrodeposition, the method further comprises: washing the composite material after cathode electrodeposition with deionized water, then washing with anhydrous ethanol, and then drying naturally.

6. The method for preparing a high-efficiency alkaline water electrolysis oxygen evolution electrode according to claim 1, characterized in that: In step B), the anode and cathode react simultaneously. The anode undergoes an electro-etching reaction, roughening the surface of the new nickel mesh, and the cathode undergoes an electrodeposition reaction, depositing nickel-iron catalyst on the surface that was electro-etched in the previous round of reaction.

7. The method for preparing a high-efficiency alkaline water electrolysis oxygen evolution electrode according to claim 1, characterized in that: The cathode and anode after the electrodes are replaced and reversed in step C) are directly used in step B), so that new electrodeposition is performed on the electro-etched surface, while a new electrode is electro-etched at the other pole.

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