A rapid preparation method and application of a NiFe-LDH nickel-based electrode

Abstract

The present invention discloses a rapid preparation method and application of a NiFe-LDH nickel-based electrode, belonging to the technical fields of electrolytic water hydrogen production and anion exchange membrane electrolytic water. The preparation method includes the following steps: S1. Under normal temperature and pressure, immerse the cleaned nickel-based substrate material into a ferric iron (Fe<supgt;3+< / supgt;) etching solution for chemical etching, let it stand for an appropriate time to fully react, and then take it out and dry; S2. Immerse the material obtained in step S1 into a strong alkaline solution for soaking treatment, let it stand for an appropriate time to fully react, and then take it out and dry; S3. Assemble the electrode material prepared in step S2 into a membrane electrode, and install it into a single cell of an anion exchange membrane electrolytic water tank for testing, so that it can stably convert electrical energy into hydrogen energy during operation. This technical solution can rapidly, low-cost, greenly and in large quantities prepare an electrolytic water anode electrode, overcomes the drawbacks of the cumbersome electrode preparation methods in the current same field, and is expected to promote the commercial development of alkaline membrane electrolytic water hydrogen production technology.

Description

Technical Field

[0001] The present invention relates to the technical fields of hydrogen production by electrolyzing water and anion exchange membrane electrolyzing water, and particularly relates to a rapid preparation method and application of a NiFe-LDH nickel-based electrode. Background Art

[0002] At present, according to the report of the BP Statistical Review of World Energy, as of 2020, fossil energy accounted for 83.1% of the global energy structure consumption, still remaining at a high level. At this rate of energy consumption, global oil, coal, and natural gas will be exhausted within 200 years. On the other hand, the use of fossil energy has led to an increase in global carbon emissions. In 2022, the global average temperature has risen by 1.5°C compared to before the Industrial Revolution. The excessive temperature has led to extreme environments around the world. Therefore, in order to reduce dependence on fossil energy and strengthen environmental protection, it is particularly important to vigorously develop renewable energy. However, renewable energy still faces the dilemmas of strong volatility and serious curtailment of electricity. Hydrogen (H2) is an energy carrier with extremely high mass energy density and is also an important industrial raw material in China. Hydrogen can be used as a "medium" for renewable energy to cleanly store and release electrical energy, enabling people to better utilize renewable energy. As the "ultimate energy in the 21st century", in terms of both energy and production, the development and utilization of hydrogen play a crucial role in China's national economy and people's livelihood and energy strategic development.

[0003] Hydrogen can be classified into "gray hydrogen", "blue hydrogen", and "green hydrogen" according to its source. Among them, "gray hydrogen" and "blue hydrogen" are more or less involved in carbon emissions during the production process, while "green hydrogen" is a more environmentally friendly hydrogen production method. Using technologies represented by ion exchange membrane electrolysis of water and combining renewable energy power generation to produce hydrogen is a very promising low-carbon hydrogen production technology solution under the background of the current efficient layout of electric energy. In the currently developed electrolysis water technologies, according to the carriers in the electrolysis device membrane, the electrolysis water technologies can be divided into acidic membrane (PEM) electrolysis water and alkaline membrane (AEM) electrolysis water. Among them, acidic electrolysis water has relatively strict requirements for electrode materials and can only use expensive noble metal catalysts as electrode materials, thus restricting its commercial development; alkaline membrane electrolysis water has relatively mild reaction conditions and can use non-precious metals with higher abundances in the earth as electrode materials, which is expected to further reduce the cost of ion exchange membrane electrolysis water and thus accelerate the commercialization of hydrogen production by electrolyzing water.

[0004] At present, the development of high-performance and stable electrode materials is a key topic for constructing high-performance AEM water electrolysis devices. For the hydrogen production industry, to prevent the "choking neck" problem at the source, it is of great significance to design efficient and inexpensive non-precious metal electrodes from the upstream. However, the oxygen evolution reaction (OER) kinetics at the anode in water electrolysis is slow, resulting in a large overpotential, consuming extra electrical energy, and thus limiting its large-scale industrial application. Some precious metals and their oxides, such as Ru, Ir, RuO2, and IrO2, are recognized as the most excellent OER electrocatalysts in acidic media. However, due to their low abundance, high cost, and poor stability when used in alkaline environments, their large-scale popularization and application are greatly restricted. Currently, transition metals (such as Fe, Co, Ni) and carbon materials are abundant in the earth, low in cost, and their easily adjustable electronic states can reduce the thermodynamic reaction energy barrier of the materials during water electrolysis, which is beneficial to improving the electrocatalytic efficiency. Therefore, they are very suitable for designing into efficient OER electrocatalysts. Transition metals iron, cobalt, nickel, and their oxides have received extensive attention and research in the field of hydrogen energy storage / conversion applications due to their low cost, sufficient sources, and good corrosion resistance in alkaline solutions. In this context, nickel-iron double hydroxide (NiFe-LDH) has been proven by researchers in various countries to be an OER electrocatalyst with good performance. However, most of the relevant literature and patented technologies reported currently use extremely complex and cumbersome preparation methods to synthesize NiFe-LDH materials, which have problems such as more steps, greater energy consumption, and poor reproducibility, and are not suitable for large-scale commercial rapid preparation. Seeking a rapid, batch, and repeatable synthesis method at room temperature to prepare NiFe-LDH catalytic electrodes has important industrial significance and commercial value. Summary of the Invention

[0005] The object of the present invention is to overcome the disadvantages of the existing technology and propose a rapid preparation method and application of a NiFe-LDH nickel-based electrode. The present invention uses room-temperature Fe 3+ etching method to directly grow nickel-iron layered double hydroxide (NiFe-LDH) nanosheets on nickel-based substrates such as nickel foam (nickel felt, nickel mesh) in an extremely short time (less than 10 minutes). The technical solution can realize the integration of the catalytic layer and the diffusion layer in the alkaline membrane water electrolysis device and has been successfully applied in the device. This method has the characteristics of great price advantage, repeatability, energy conservation and environmental protection, and easy large-scale production and preparation.

[0006] To achieve the above object, the present invention provides a technical solution:

[0007] The present invention first uses trivalent iron ions (Fe 3+)As a liquid etching solvent, the Ni substrate material is etched at room temperature and atmospheric pressure to displace Ni atoms on the surface of the Ni substrate, forming abundant rough sites on its surface and increasing the electrochemically active area of the electrode. Subsequently, at room temperature, the etched Ni electrode is dried at room temperature and atmospheric pressure, and Ni and Fe ions carried on its surface form a uniform nickel-iron oxide (NiFeO x )nanosheets under the action of air. Subsequently, the NiFeO x is soaked and then dried. The NiFeO x will be rapidly converted into NiFe-LDH. Thus, the Ni substrate-supported NiFe-LDH electrode material is finally obtained using the present invention. Using the technical solution proposed by the present invention, the NiFe-LDH electrode material can be prepared conveniently, rapidly, and greenly, with the characteristics of being repeatable, scalable, safe, and efficient. At the same time, this method has a wide applicability and can be applied to the preparation of NiFe-LDH grown on all Ni substrate materials. The NiFe-LDH nanosheets prepared in the present technical solution are in-situ grown, tightly combined with the Ni substrate, macroscopically uniform, non-powdery, and non-detachable. The NiFe-LDH nanosheets vertically root on the nickel substrate and cross each other to form a self-supporting structure with a highly porous array, resulting in a large number of exposed active sites, which not only reduces the charge / mass transfer resistance but also enhances the mechanical stability, and has good OER activity and stability in half-cells and electrolyzer full-cells.

[0008] Optionally, the Ni substrate material used in the present invention is one or more of nickel foam, nickel felt, and nickel mesh.

[0009] Optionally, the ferric ion etching solution used in the present invention is one or more of FeCl3, Fe2(SO4)3, and Fe(NO3)3 solutions.

[0010] Optionally, the molar concentration of the ferric ion etching solution Fe 3+ used in the present invention is 0.5 M to 1 M.

[0011] Optionally, the etching time for etching the Ni-based substrate material with ferric ions in the present invention is 1 min to 10 min.

[0012] Optionally, the drying method used in the present invention is one or more of drying at room temperature by static placement and drying in an oven with forced air.

[0013] Optionally, the strong alkaline soaking solution used in the present invention is one or more of NaOH or KOH.

[0014] Optionally, the strong alkaline soaking solution OH -The concentration is 0.1 M to 2 M.

[0015] Optionally, the strong alkaline soaking time used in the present invention is 1 min to 10 min.

[0016] Optionally, when the NiFe-LDH works in an alkaline membrane electrolytic cell, the anode material is NiFe-LDH supported on a nickel substrate, the cathode electrode material is nickel molybdenum alloy foam, and the cathode reaction equation of the electrolytic water tank is 4H2O + 4e - →2H2 + 4OH - , and the anode reaction equation is 4OH - -4e - →O2 + 2H2O, and the total reaction is 2H2O → 2H2 + O2.

[0017] Compared with the prior art, the present invention adopts the above technical solutions, and the principle is as follows. In this technical solution, transition metal (nickel and iron) oxides are used as the active substance of the electrode material. Substantially, a hydrotalcite structure is constructed on the Ni substrate, and the molecular structure of the hydrotalcite is an octahedral structure based on the expansion of brucite (Mg(OH)6). We use Ni 2+ , Fe 3+ as divalent and trivalent cations to replace the metal sites respectively, so that the electrode is positively charged and can adsorb a negatively charged hydration layer on its surface, enabling this NiFe-LDH structure to exhibit its superior OER catalytic activity under alkaline conditions. At the high anodic potential of electrolyzing water, electrons can cause the surface of the Ni metal oxide to be reconstructed, dissociating water, and the doping of iron elements further optimizes the electronic structure of NiFe-LDH, thereby generating excellent active sites for the OER reaction. However, the currently reported NiFe-LDH electrode synthesis technical routes often have some defects:

[0018] (1) The synthesis method is complex, with huge energy consumption and poor environmental friendliness, not in line with the concept of green energy.

[0019] (2) The electrode resistance is large. The synthesized layered double metal hydroxide is not tightly linked to the substrate, causing problems such as easy detachment of nanosheets and large resistance under actual high-current and strong gas evolution conditions.

[0020] (3) The electrode activity and hydrophilicity are poor, and the electrochemically active area is small, resulting in difficult mass transfer, and the generated bubbles cover and hinder the active sites.

[0021] Although NiFe-LDH materials have been proven to have good OER electrocatalytic activity, the above three defects severely limit the large-scale application and commercial development of NiFe-LDH. Based on this, this technical solution innovatively uses room-temperature and atmospheric-pressure ion etching to roughen the surface of the Ni-based substrate, creating a large number of "sites" for growing NiFe-LDH, and combining two simple methods of air oxidation and strong alkali immersion to firmly construct NiFe-LDH nanosheets on the Ni substrate material. The NiFe-LDH preparation method proposed in this technical solution is simple to operate, low in cost, easy to scale up, and has been well applied in electrochemical half-cells and full-cell electrolyzers.

[0022] The technical solution proposed by the present invention has the following advantages:

[0023] (1) The ion etching method described in this technical solution has a simple and mature process, without complex operations and expensive consumables and chemicals, and can be carried out at room temperature.

[0024] (2) The strong alkaline solutions used in this technical solution can be recycled and reused, and can have great environmental protection value while ensuring experimental consistency.

[0025] (3) The method for constructing NiFe-LDH nanosheet arrays proposed in this technical solution has good applicability to a variety of Ni-based substrate materials (nickel felt, nickel foam, nickel mesh), showing great potential for promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0027] Figure 1 Schematic diagram of the steps for the rapid preparation method of a Ni-based electrode loaded with NiFe-LDH proposed by the present invention;

[0028] Figure 2 Scanning electron microscope image of NiFe-LDH prepared with nickel felt as the substrate by the present invention;

[0029] Figure 3 OER polarization curve of the half-cell of NiFe-LDH prepared with nickel felt as the substrate in the present invention;

[0030] Figure 4 Polarization curve of the alkaline membrane electrolyzed water single cell of NiFe-LDH prepared with nickel felt as the substrate in the present invention;

[0031] Figure 5 The Nyquist impedance diagram of a single cell using the NiFe-LDH alkaline membrane water electrolysis prepared using nickel felt as a substrate in the present invention;

[0032] Figure 6 This is a graph showing the hydrogen production efficiency of a single cell using the NiFe-LDH alkaline membrane water electrolysis cell prepared using nickel felt as a substrate in the present invention;

[0033] Figure 7 The OER polarization curve of the NiFe-LDH half-cell prepared using nickel foam as the substrate in the present invention;

[0034] Figure 8 Polarization curve of a single cell using NiFe-LDH alkaline membrane water electrolysis prepared with nickel foam as substrate in the present invention; DETAILED DESCRIPTION

[0035] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the examples described are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention. Specific embodiment 1

[0037] This specific embodiment will use nickel felt as a substrate to prepare NiFe-LDH electrode material as a demonstration to illustrate the technical solution.

[0038] The schematic diagram of the process of this technical solution is shown in the attached figure Figure 1 shown.

[0039] Step 1. First, pre-treat the substrate material. Take a nickel felt substrate material with a thickness of 500 μm and a porosity of 75%, use a die cutter to cut it into a square structure with an area of 2.25*2.25 cm, and use a roller press or a hot press to flatten the edges of the cut substrate to prevent the raised metal fibers from puncturing the membrane when assembling the electrolytic water device. Subsequently, use ultrapure water and anhydrous ethanol to place the cut nickel felt material in a beaker for water bath ultrasonic cleaning 3 times, use acetone to clean the nickel felt material in a water bath ultrasonic cleaning for 30 minutes, and completely clean the grease and organic matter on the surface of the metal nickel. Then use ultrapure water and anhydrous ethanol to rinse the residual acetone, and then use 3M HCl solution to pickle and etch the oxide on the surface of the nickel felt. The pickling condition is water bath ultrasonic cleaning for 30 minutes to remove the surface oxide of the material and enhance the conductivity of the material. Rinse the treated nickel felt substrate with ultrapure water and place it in a clean beaker for standby use.

[0040] Step 2. Use Fe3+ Etch the nickel felt substrate with the solution at room temperature. First, prepare a 0.5M FeCl3 solution, transfer the FeCl3 solution to a clean petri dish and let it stand for a period of time to stabilize the pH value of the solution. Then, fully immerse the treated nickel felt substrate into the FeCl3 solution for etching at room temperature. After standing for 4 minutes, take it out and dry it naturally at room temperature. At this time, the surface of the electrode is light blue, which is the color shown by the adsorption of nickel ions and iron ion solutions on the surface of the nickel felt.

[0041] Step 3. Treat the nickel felt electrode with hydroxyl adsorption using a strong base solution. First, prepare a 1M NaOH solution, transfer the NaOH solution to a clean petri dish, and fully immerse the nickel felt electrode dried in Step 2 into the NaOH solution, so that the high-concentration OH - ions in NaOH are in full contact with the NiFeO x formed on the surface of the nickel felt for 1 minute, and then take it out and dry it at room temperature. Under the combined action of air and OH - ions, NiFeO x is transformed into a NiFe-LDH nanorod array. As shown in the attached figure Figure 2 When observed using a high-magnification transmission electron microscope for the synthesized NiFe-LDH, it is found that the NiFe-LDH nanosheets are vertically rooted in the nickel felt and cross each other to form a highly uniform porous array. This structure is conducive to the full contact of the electrode interface with the electrolyte and the construction of a nickel-based oxygen evolution electrode with a high specific surface area. On the other hand, in the synthesis, both Ni and Fe are formed by in-situ growth, and the synthesized NiFe-LDH is tightly combined with the nickel felt fibers, forming an integrated self-supporting electrode material, making the entire electrode have very ideal conductivity.

[0042] Step 4. Use a three-electrode system to perform an intrinsic activity test on the NiFe-LDH nickel-based electrode in a half-cell. First, prepare a 1M KOH solution as the electrolyte solution, fix the NiFe-LDH electrode prepared in Step 3 on a gold electrode clip as the working electrode, use a saturated calomel electrode (SCE) as the reference electrode, and use a graphite carbon rod as the counter electrode. Pass in high-purity O2 to set the electrolyte atmosphere to an O2-saturated state. Subsequently, perform an OER activity test on the catalyst in the potential window of 1.0V - 1.8V (vs. RHE) in 1M KOH using a linear voltammetry scanning program. The obtained polarization curve is as shown in the attached figure Figure 3 In this example, the NiFe-LDH electrode synthesized with nickel felt as the substrate material shows good intrinsic activity in an alkaline medium, and only requires low overpotentials of 200 and 240 mV to reach current densities of 100 and 500 mA cm -2 .

[0043] Step 5. Use a two-electrode system to evaluate the water electrolysis activity of the NiFe-LDH nickel-based electrode in an alkaline membrane single-cell electrolyzer. In this example, Versogen PiperION-A80-HCO3 alkaline membrane is used as the solid electrolyte, a commercial foam nickel-molybdenum alloy material is used as the hydrogen evolution electrode at the cathode, and the NiFe-LDH nickel-based electrode synthesized in Step 3 is used as the oxygen evolution electrode at the anode. The cathode and anode electrodes are respectively attached to both sides of the alkaline membrane. By using a 5 cm 2 graphite and titanium flow field plate fixture to assemble and fasten the membrane electrode, and introducing 6M KOH alkaline solution into the fixture as the electrolyte and carrier of current carriers. The temperature of the full-cell electrolyzer is set at 60 °C, and both the cathode and anode are fed on both sides. Use a Shuleiqiang electrochemical comprehensive test system (Modulab XM, 25A) to perform electrochemical polarization on the assembled single cell. The electrochemical polarization range is set at 1.0 V to 2.5 V. As shown in the attached figure Figure 4 shows that the performance of the single-cell electrolyzer assembled in this specific example is good. The performance of the assembled single electrolyzer cell reaches 1.2 A cm at 2 V voltage -2 , which is higher than the reported performance of commercial IrO2 / Pt / C at present, and excellent single-cell water electrolysis activity is achieved. At the same time, in this example, the high-frequency alternating current impedance method is used to test the single cell. As shown in the attached figure Figure 5 shows that the internal resistance of the battery is about 0.044 mΩ, showing extremely high ion conduction characteristics of the electrochemical system, which is beneficial to reducing the power consumption during water electrolysis for hydrogen production and is suitable for industrial applications. As shown in the attached figure Figure 6 shows the hydrogen production efficiency of the AEMWE device in the working state assembled in this specific example. Within 60 minutes, the generated H2 is in good agreement with the theoretical value, and the hydrogen production efficiency reaches 99.5%, indicating that there is no short-circuit current inside the assembled AEMWE, and almost all the consumed electrical energy is converted into chemical energy in H2, confirming that the device assembled with the NiFe-LDH nickel-based electrode synthesized by this technical solution has the ability to produce hydrogen. Specific Example 2

[0045] This specific example will demonstrate the preparation of the NiFe-LDH electrode material with nickel foam as the substrate to elaborate on this technical solution.

[0046] A schematic diagram of the process of this technical solution is shown in the attached figure Figure 1 as shown.

[0047] Step 1. First, perform pretreatment on the substrate material. Take a substrate with a thickness of 1.5 mm and a surface density of 400 g·m -2The nickel foam base material is cut into a square structure with an area of 2.25*2.25cm using a die cutter, and the edges of the cut base are flattened using a roller press or a hot press to control the thickness of the nickel foam to about 300μm, and to prevent the warped metal fibers from puncturing the membrane when assembling the electrolytic water device. Subsequently, the cut nickel foam material is placed in a beaker and ultrasonically cleaned in a water bath for 3 times using ultrapure water and anhydrous ethanol, and the nickel foam material is cleaned in an ultrasonic water bath for 30 minutes using acetone to completely clean the grease and organic matter on the surface of the metal nickel, and then the residual acetone is rinsed with ultrapure water and anhydrous ethanol, and then the oxide on the surface of the nickel foam is pickled and etched with a 3M HCl solution, and the pickling condition is ultrasonic water bath for 30 minutes to remove the oxide on the surface of the material and enhance the conductivity of the material. The treated nickel foam base is rinsed with ultrapure water and placed in a clean beaker for standby use.

[0048] Step 2. Use Fe 3+ The solution etches the nickel foam substrate at room temperature. First, prepare a 0.5M FeCl3 solution, transfer the FeCl3 solution to a clean surface dish and let it stand for a while to stabilize the pH value of the solution. Then, fully immerse the treated nickel foam substrate in the FeCl3 solution for room temperature etching, take it out after standing for 4 minutes, and dry it naturally at room temperature. At this time, the electrode surface is light blue, which is the color of the nickel ion and iron ion solution adsorbed on the surface of the nickel foam.

[0049] Step 3. Use a strong alkaline solution to perform hydroxyl adsorption treatment on the nickel foam electrode. First, prepare a 1M NaOH solution, transfer the NaOH solution to a clean surface dish, and fully immerse the nickel foam electrode dried in step 2 in the NaOH solution to allow the high concentration of OH- ions in the NaOH to react with the NiFeO formed on the surface of the nickel foam. x Fully contact for 1 minute, then take out and place at room temperature to dry. - Under the combined action of ions, NiFeO x Converted into NiFe-LDH nanoarray. The NiFe-LDH nanosheets are vertically rooted in the nickel foam and cross each other to form a highly uniform porous array. This structure is conducive to the electrode interface to fully contact the electrolyte and build a nickel-based oxygen evolution electrode with a high specific surface area. On the other hand, in the synthesis, Ni and Fe are both formed by in-situ growth, and the synthesized NiFe-LDH is tightly combined with the nickel foam fiber to form an integrated self-supporting electrode material, which makes the entire electrode have very good conductivity.

[0050] Step 4. Use a three - electrode system to perform an intrinsic activity test on the NiFe - LDH nickel - based electrode in a half - cell. First, prepare 1 M KOH solution as the electrolyte solution. Fix the NiFe - LDH electrode prepared in Step 3 on the gold electrode clip as the working electrode, use a saturated calomel electrode (SCE) as the reference electrode, and use a graphite carbon rod as the counter electrode. Pass high - purity O2 to set the electrolyte atmosphere to O2 - saturated state. Subsequently, use a linear voltammetry scanning program in 1 M KOH to perform an OER activity test on the catalyst in the potential window of 1.0 V - 1.8 V (vs. RHE). The obtained polarization curve is as shown in the attached figure Figure 7 as shown. In this example, the NiFe - LDH electrode synthesized with nickel foam as the substrate material shows good intrinsic activity in alkaline medium, and only requires low overpotentials of 240 and 280 mV to reach current densities of 100 and 500 mA cm -2 .

[0051] Step 5. Use a two - electrode system to evaluate the water electrolysis activity of the NiFe - LDH nickel - based electrode in an alkaline membrane single - cell electrolyzer. In this example, use Versogen PiperION - A80 - HCO3 alkaline membrane as the solid electrolyte, use commercial nickel - molybdenum alloy foam material as the hydrogen - evolution electrode at the cathode, and use the NiFe - LDH nickel - based electrode synthesized in Step 3 as the oxygen - evolution electrode at the anode. Attach the cathode and anode electrodes on both sides of the alkaline membrane respectively. Assemble and fasten the membrane electrode through a 5 cm 2 graphite and titanium flow - field plate and fixture, and introduce 1 M KOH alkaline solution into the fixture as the electrolyte and carrier. Set the temperature of the full - cell electrolyzer to 60 °C, feed both sides of the cathode and anode, and use a Shuleiqiang electrochemical comprehensive test system (Modulab XM, 25 A) to perform electrochemical polarization on the assembled single - cell. Set the electrochemical polarization range to 1.0 V - 2.5 V. As shown in the attached figure Figure 8 as shown, the single - cell water - electrolysis device assembled in this specific example has good performance, and the performance of the assembled single - cell electrolyzer reaches 0.7 A cm at 2 V voltage -2 , achieving excellent single - cell water - electrolysis activity. Specific Example 3

[0053] This specific example will demonstrate the preparation of the NiFe - LDH electrode material with a nickel mesh as the substrate to elaborate on this technical solution.

[0054] A schematic diagram of the process of this technical solution is briefly shown in the attached figure Figure 1 as shown.

[0055] Step 1. First, pre-treat the substrate material. Take a nickel mesh substrate material with a wire diameter of 60 μm and a mesh size of 200 mesh, use a die cutter to cut it into a square structure with an area of 2.25*2.25 cm, and use a roller press or a hot press to flatten the edges of the cut substrate to prevent the warped metal fibers from puncturing the membrane when assembling the electrolytic water device. Subsequently, use ultrapure water and anhydrous ethanol to place the cut nickel mesh material in a beaker for water bath ultrasonic cleaning 3 times, use acetone to clean the nickel mesh material in a water bath ultrasonic cleaning for 30 minutes, and completely clean the grease and organic matter on the surface of the metal nickel, then use ultrapure water and anhydrous ethanol to rinse the residual acetone, and then use 3M HCl solution to pickle and etch the oxide on the surface of the nickel mesh, and the pickling condition is water bath ultrasonic cleaning for 30 minutes to remove the surface oxide of the material and enhance the conductivity of the material. Rinse the treated nickel mesh substrate with ultrapure water and place it in a clean beaker for standby use.

[0056] Step 2. Use Fe 3+ The solution etches the nickel mesh substrate at room temperature. First, prepare a 1M FeCl3 solution, transfer the FeCl3 solution to a clean surface dish and let it stand for a while to stabilize the pH value of the solution. Then, fully immerse the treated nickel mesh substrate in the FeCl3 solution for room temperature etching, take it out after standing for 10 minutes, and dry it naturally at room temperature. At this time, the electrode surface is light blue, which is the color of the nickel ion and iron ion solution adsorbed on the surface of the nickel mesh.

[0057] Step 3. Use a strong alkaline solution to treat the nickel mesh electrode with hydroxyl groups. First, prepare a 1M NaOH solution, transfer the NaOH solution to a clean surface dish, and fully immerse the dried nickel mesh electrode in the NaOH solution to allow the high concentration of OH- ions in the NaOH to react with the NiFeO formed on the surface of the nickel mesh. x Fully contact for 5 minutes, then take out and place at room temperature to dry. - Under the combined action of ions, NiFeO x Converted into NiFe-LDH nanoarray. The NiFe-LDH nanosheets are vertically rooted in the nickel mesh and cross each other to form a highly uniform porous array. This structure is conducive to the electrode interface to fully contact the electrolyte and build a nickel-based oxygen evolution electrode with a high specific surface area. On the other hand, in the synthesis, Ni and Fe are both formed by in-situ growth, and the synthesized NiFe-LDH is tightly combined with the nickel mesh fiber to form an integrated self-supporting electrode material, which makes the entire electrode have very good conductivity. Specific embodiment 4

[0059] This specific embodiment statistically analyzes and verifies the simplicity of the technical route proposed in this technical solution.

[0060] In Specific Examples 1 to 3, the pretreatment (pickling and acetone cleaning) method for the nickel substrate material is a common route in the art and is background knowledge known to those within the field. Therefore, it can be considered that the pretreatment step is not included in the necessary synthesis steps of the NiFe-LDH nickel-based electrode in the present technical invention.

[0061] In Specific Examples 1 to 3, the rapid preparation method of the NiFe-LDH nickel-based electrode is applicable to three porous metal materials: nickel felt, nickel foam, and nickel mesh, indicating its wide applicability to the substrate, thus demonstrating its universality and simplicity.

[0062] In Specific Examples 1 to 3, an experimental timing analysis was carried out on the rapid preparation process of the NiFe-LDH nickel-based electrode. The preparation processes took 9 minutes, 8 minutes, and 8 minutes respectively. After searching in the patent database, it was found that most of the preparation methods of the NiFe-LDH nickel-based electrode involve hydrothermal synthesis and electrodeposition preparation, and their time consumption involves several hours, thus highlighting the innovation and uniqueness of the rapid preparation of this technical solution.

[0063] In Specific Examples 1 to 3, an energy consumption analysis was carried out on the rapid preparation process of the NiFe-LDH nickel-based electrode. During the synthesis process, high-temperature, high-pressure conditions and dangerous chemicals were not used, indicating that this technical solution has the technical characteristics of low power consumption, greenness, and no pollution.

[0064] In Specific Examples 1 to 3, an experimental equipment statistics was carried out on the rapid preparation process of the NiFe-LDH nickel-based electrode. During the synthesis process, no relevant synthesis electrical equipment was used. Only beakers and watch glasses were counted as glass instruments, and the containers and utensils involved are all scalable, indicating that this technical solution has the advantages of macroscale preparation and large-scale production.

[0065] In summary, compared with the prior art, the present invention adopts the above technical solutions, which can realize the rapid, simple and low-power synthesis of a NiFe-LDH nickel-based oxygen evolution electrode with excellent performance. On the premise of ensuring the excellent OER electrocatalytic activity of the NiFe-LDH nickel-based electrode, the time cost and energy consumption cost in the material preparation process are greatly reduced. It should be noted that various strategies for preparing NiFe-LDH have been continuously developed, but these methods are often too elaborate and the steps are relatively cumbersome, and there are problems with reproducibility. Most of the synthesis methods require high temperature and high pressure, which will not only increase the synthesis cost of NiFe-LDH, but also run counter to the concept of green energy and low-carbon emissions. The above problems have greatly hindered the large-scale application of NiFe-LDH as an oxygen evolution electrode. Therefore, it is extremely important to develop a method for preparing a rapid NiFe-LDH nickel-based material without additional energy consumption in this case. In the present invention, an innovative technical route is proposed, which can synthesize a NiFe-LDH double hydroxide nanosheet array vertically rooted on a nickel substrate material within less than 10 minutes. It has high roughness, excellent mechanical strength and conductivity, and the nanosheet morphology is uniform and reproducible. In the half-cell test, it shows excellent intrinsic activity. To verify the technical route, the NiFe-LDH nickel-based electrode prepared using nickel felt as the substrate has overpotentials of only 200 and 240 mV corresponding to current densities of 100 mA cm -2 and 500 mA cm -2 ; in the full-cell test, the performance of the single-cell electrolyzer assembled with the NiFe-LDH nickel-based electrode prepared using nickel felt as the substrate reaches 1.2 A cm -2 at a voltage of 2.0 V, which is higher than the performance of the reported commercial IrO2 / Pt / C at present, and excellent single-cell water electrolysis activity is achieved; at the same time, the internal resistance of the single cell is about 0.044 mΩ, showing excellent device resistance characteristics; in the test of hydrogen production efficiency, its hydrogen production efficiency reaches 99.5%, indicating that the material is stable and no oxidation has occurred. In short, the technical solution proposed by the present invention has good compatibility with the prior art, can be directly matched and applied without changing the existing single-cell structure, and has the advantages of convenience, high efficiency and easy operation. This synthesis technical route of a rapid, low-cost, highly active and high-current OER electrode can be applied in an electrolytic water stack, and is expected to promote the commercial development of alkaline membrane electrolytic water hydrogen production technology.

[0066] Of course, the one-way features or combinations of features of the feature embodiments can be combined with the features and combinations of features of other examples to produce additional embodiments. In addition, features or combinations of features not described in the embodiments should of course be understood as supplements to the corresponding embodiments. The above are only the preferred embodiments of the present invention, which are illustrative rather than restrictive to the present invention; those of ordinary skill in the art understand the spirit defined by the claims of the present invention.

Claims

1. A rapid preparation method of a NiFe-LDH nickel-based electrode, characterized in that, It includes the following steps: S1. At normal temperature and pressure, immerse the cleaned nickel-based substrate material into a ferric (Fe 3+ ) etching solution for chemical etching, let it stand for an appropriate time to fully react, and then take it out and dry it; S2. Immerse the material obtained in step S1 in a strongly alkaline solution for soaking treatment, let it stand for an appropriate time to fully react, and then take it out and dry it; S3. Assemble the electrode material prepared in step S2 into a membrane electrode, and install it in a single cell of an anion exchange membrane electrolytic water tank for testing, so that it can stably convert electrical energy into hydrogen energy during operation.

2. The preparation method according to claim 1, characterized in that, In step S1, the nickel-based substrate material is one or more of nickel felt, nickel foam and nickel mesh.

3. The preparation method according to claim 1, characterized in that, In step S1, the ferric (Fe 3+ ) etching solution is one or more of FeCl3, Fe2(SO4)3, and Fe(NO3)3 solutions.

4. The preparation method according to claim 1, characterized in that, In step S1, the Fe in the ferric (Fe 3+ ) etching solution 3+ has a concentration of 0.5 M to 1 M.

5. The preparation method according to claim 1, characterized in that, In step S1, the etching standing time is 1 min to 10 min.

6. The preparation method according to claim 1, characterized in that, In step S1, the drying method is one or more of room temperature drying or blowing drying in an electric oven.

7. The preparation method according to claim 1, characterized in that, In step S2, the strongly alkaline solution is one or more of NaOH or KOH.

8. The preparation method according to claim 1, wherein In step S2, the soaking and standing time is 1 min to 10 min.

9. The preparation method according to claim 1, characterized in that, In step S2, the drying method is one or more of room temperature drying or blowing drying in an electric oven.

10. A NiFe-LDH nickel-based electrode, characterized in that, Prepared by the preparation method according to any one of claims 1 to 9.

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