Alkaline OER electrode based on nickel-iron-based hydroxide

Abstract

The invention discloses an alkaline OER electrode based on a nickel-iron-based hydroxide, which is prepared by the following steps: dissolving nickel salt and cobalt salt in deionized water to prepare a solution A; dissolving a metal chelating agent in deionized water to prepare a solution B; ferrocene dicarboxylic acid and ferrocene carboxylic acid are used as iron salts to be dissolved in an organic solvent, and a solution C is prepared; adding the solution A and the solution C into the solution B to prepare a mixed solution; and finally, putting the nickel wire mesh substrate with the nickel salt layer on the surface into the mixed solution, and carrying out hydrothermal reaction. The alkaline OER electrode disclosed by the invention is high in stability and high in activity; specifically, the voltage growth rate of long-time polarization is only 1.8%, the ultrasonic peeling rate is only 0.08%, the overpotential can be reduced to 252mV, and the potential change is only 0.026 mV.

Description

Technical Field

[0001] The invention belongs to the field of alkaline OER electrode preparation, and in particular relates to an alkaline OER electrode based on nickel-iron hydroxide. Background Art

[0002] Hydrogen production from water electrolysis driven by renewable electricity is a promising strategy to overcome the intermittent and diffusive nature of renewable energy sources such as solar and wind energy, thereby facilitating their continuous use and distribution. However, the widespread implementation of this system is severely hampered by the sluggish reaction kinetics associated with the two half reactions in water electrolysis, namely, the anodic oxygen evolution reaction (OER) and the cathodic hydrogen evolution reaction (HER). Therefore, a great deal of research effort has been devoted to reducing the overpotentials of OER and HER by developing efficient catalyst electrodes.

[0003] However, the widely used catalysts are still limited to single-functional noble metals, such as IrO2 and RuO2 for OER and Pt for HER, while the high cost and scarcity of these noble metals seriously undermine their commercial potential. Therefore, it is extremely challenging to develop transition metal catalyst electrodes with dual functionality and catalytic activity comparable to that of noble metals to achieve economically viable hydrogen production by water electrolysis. To date, various transition metal-based composite catalyst electrodes, including oxides, (oxy)hydroxides, chalcogenides, selenides, carbides, and TM-modified steels have been reported for OER and HER electrodes. Among them, transition metal-based (oxy)hydroxide electrodes have aroused special research interest in OER electrodes due to their unique molecular formula, easily adjustable three-dimensional electronic structure, and satisfactory electrocatalytic performance, especially nickel-iron-based hydroxide catalyst electrodes.

[0004] For example, Chinese patent CN113463129B discloses the preparation and application of a carboxyl intercalated nickel-iron-lithium layered hydroxide electrocatalyst, and prepares a carboxyl intercalated nickel-iron-lithium layered hydroxide composite material with a two-dimensional-three-dimensional super structure and a specific proton transfer center through a simple soaking reaction, and applies it to the field of electrocatalysis, enriching the synthesis and preparation technology of layered hydroxides, and also greatly broadening its commercial application value. However, in this invention, nickel foam is used as the base material of the electrode. Under the influence of high current density and alkaline electrolyte erosion, the nickel foam will dissolve, the electrode structure will be damaged, and the stability is poor.

[0005] For example, Chinese patent CN115125569B discloses a nickel-iron hydroxide electrocatalyst and its preparation method and application. By using an electrochemical pulse method, positive and negative voltages are applied at certain intervals to treat nickel foam, driving the electrochemical surface reconstruction of the nickel foam surface, dissolving the unstable nickel hydroxide structure, and generating more stable and active nickel-iron hydroxide active centers, which greatly improves the activity and stability of nickel-iron hydroxide under high current density. The raw materials used in this invention are widely available, low in cost, and simple in preparation process, making it suitable for large-scale industrial production. However, no alkaline buffer is used in this invention, Fe 3+ It cannot grow uniformly and in large quantities on the surface of nickel foam, and the electrode activity is low and the stability is poor.

[0006] For another example, Chinese patent CN114808014B discloses a novel multilayer metal hydroxide electrocatalyst, preparation method and application thereof, wherein cobalt nitrate and iron nitrate are used as raw materials, and cobalt hydroxide is first deposited on nickel foam by cathode electrodeposition, and then a layer of iron hydroxide is deposited on cobalt hydroxide, and then a layer of cobalt hydroxide is deposited on iron hydroxide, and this process is repeated alternately to prepare 1, 3, 5, and 7 layers of cobalt iron hydroxide electrocatalysts, and multilayer metal hydroxides can be obtained, which are prepared at room temperature, are simple and energy-saving, and the catalyst obtained by the electrodeposition method is tightly combined with the nickel foam substrate, and a multilayer metal hydroxide catalyst electrode can be obtained after repeated deposition. However, the hydroxide nanosheets prepared in the invention have only a small number of corners, which limits the number of active sites, and the nickel foam is used as the substrate material, so the electrode activity is low and the stability is poor.

[0007] Although the performance of the OER electrodes reported so far based on nickel-iron hydroxides is much higher than that of commercial RuO2 and IrO2, they still have problems of low activity and poor stability. Summary of the invention

[0008] Purpose of the invention: The technical problem to be solved by the present invention is to provide an alkaline OER electrode based on nickel-iron hydroxide with strong stability and high activity.

[0009] Technical solution: The present invention is based on an alkaline OER electrode of nickel-iron-based hydroxide, and the alkaline OER electrode is prepared by the following steps:

[0010] (1) dissolving 30-60 parts of nickel salt and 0-30 parts of cobalt salt in deionized water to prepare solution A;

[0011] (2) dissolving the metal chelator in deionized water to prepare solution B;

[0012] (3) dissolving 5.6-30 parts of ferrocenedicarboxylic acid and 5.6-30 parts of ferrocenylcarboxylic acid as iron salt in an organic solvent to prepare a solution C;

[0013] (4) adding solution A and solution C to solution B to prepare a mixed solution;

[0014] (5) A nickel wire mesh substrate with a nickel salt layer on its surface is placed in a mixed solution, and after hydrothermal reaction, washing and drying, an alkaline OER electrode based on nickel-iron hydroxide is prepared.

[0015] The present invention is based on a nickel wire mesh, and by arranging a nickel salt layer film thereon, and arranging a catalyst precursor solution composed of a metal chelating agent, a nickel salt and an iron salt, a one-step hydrothermal reaction can be used to directly form a catalytic layer on a substrate material by an in-situ growth method, which can reduce the resistance when the charge passes through, realize rapid charge transfer, and thus reduce the potential change after the OER electrode anti-reverse current performance test; and at the same time, based on the pre-set nickel salt layer film, under the chelation of the metal chelating agent, the nickel-iron-based hydroxide formed by the nickel and iron in the solution can be closely connected with the nickel salt layer film, thereby enhancing the bonding strength between the formed catalytic layer and the substrate material, reducing the ultrasonic peeling rate of the catalytic layer, and enhancing the ability to resist the disturbance of bubbles and liquid flow, thereby enhancing the stability of the OER electrode. The residual nickel salt layer film can also improve the crack resistance and corrosion resistance of the prepared OER electrode, and can improve the activity of the OER electrode.

[0016] Furthermore, in the preparation step (1) of the electrode of the present invention, the amount of deionized water added is 0-400 parts.

[0017] Furthermore, in the preparation step (1) of the electrode of the present invention, the nickel salt used is nickel nitrate hexahydrate, nickel chloride or nickel acetate; the cobalt salt is cobalt nitrate hexahydrate, cobalt chloride or cobalt acetate.

[0018] Furthermore, in the preparation step (2) of the electrode of the present invention, the metal chelating agent used may include at least one of tetrasodium ethylenediaminetetraacetate, iminodisuccinic acid, ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetate, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid or citric acid.

[0019] The present invention adds a metal chelating agent, which can not only tend to be adsorbed on the surface of the metal hydroxide to prevent it from aggregating, but also control the precipitation rate of the metal ions, and will not cause any phase segregation due to uncontrollable precipitation, thereby improving the uniformity of the catalyst layer; and at the same time, it can also improve the bonding strength between the formed catalyst layer and the nickel mesh substrate. Preferably, the weight proportion of the metal chelating agent is 5-10 parts, and the weight proportion of deionized water is 0-400 parts.

[0020] Furthermore, in the preparation step (3) of the electrode of the present invention, the organic solvent is N,N-dimethylformamide, methanol or ethylene glycol, and its content is 10-50 parts.

[0021] Furthermore, in the preparation step (4) of the electrode of the present invention, the nickel wire mesh is a straight or twill nickel wire mesh with a mesh size of 40-60.

[0022] The present invention adopts a 40-60 mesh straight or twill nickel wire mesh, which can ensure the structural stability of the OER electrode during long-term polarization and reduce the voltage growth rate of the OER electrode during long-term polarization.

[0023] Furthermore, in the preparation step (4) of the electrode of the present invention, the hydrothermal reaction is heated at 120-200°C for 4-12 hours; and the drying is dried at 40-60°C under vacuum for 12-24 hours.

[0024] Furthermore, in the preparation step (4) of the electrode of the present invention, the nickel wire mesh substrate with a nickel-based layer on the surface is prepared by the following steps: a square magnet is placed directly below a beaker containing a solution of 0.5-1.5 mol / L nickel salt, and the nickel mesh is placed in the solution in a direction perpendicular to the magnetic field, and an oxidizing and reducing agent is added, and the solution is taken out after standing for 5-20 minutes. Preferably, the oxidizing and reducing agent used can be sodium thiosulfate or hydrazine hydrate.

[0025] When preparing a nickel wire mesh substrate with a nickel base layer on the surface, the present invention adds a magnet to the prepared mixed solution and places the nickel mesh in a direction perpendicular to the magnetic field, so that the catalyst layer on the nickel mesh substrate can form a positioned growth, thereby improving the activity of the prepared OER electrode.

[0026] Beneficial effects: Compared with the prior art, the significant advantages of the present invention are: the alkaline OER electrode is not only highly stable but also highly active; specifically, its voltage growth rate during long-term polarization is only 1.8%, which enhances the structural stability of the OER electrode during long-term polarization and reduces the voltage growth rate of the OER electrode during long-term polarization; the ultrasonic stripping rate is only 0.08%, which enhances the electrode stability; the overpotential can be reduced to 252mV, the OER electrode activity is enhanced, and the potential change is only 0.026mV, which effectively reduces the potential change of the OER electrode after the reverse current resistance performance test and enhances the stability of the OER electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a test chart of the ultrasonic peeling rate of the OER electrodes of Example 1, Examples 15-20 and Comparative Example 4 of the present invention. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0029] It should be noted that the raw materials used in the present invention can be purchased from the market, and the nickel wire mesh was purchased from Anping County Kangxinlong Wire Mesh Manufacturing Co., Ltd. The raw material information of some of the following examples is shown in Table 1 below.

[0030] Table 1 Part of raw material information

[0031]

[0032]

[0033] The nickel wire mesh substrate with a nickel base layer on the surface of the present invention is prepared by the following steps: a square magnet is placed directly below a beaker containing a solution of 0.5-1.5 mol / L nickel salt, and a nickel mesh is placed in the solution in a direction perpendicular to the magnetic field, an oxidation-reduction agent is added, and the nickel mesh is taken out after standing for 5-20 minutes, and then rinsed with deionized water and ethanol for 3-5 times, and dried for standby use. The nickel salt can be nickel nitrate, nickel chloride, or nickel acetate. The oxidation-reduction agent can be sodium thiosulfate or hydrazine hydrate. The solution can be selected as long as it can dissolve the nickel salt, such as deionized water.

[0034] The nickel wire mesh substrate with a nickel base layer on the surface used in the following Examples 1 to 19 and Comparative Examples 1 to 3 is prepared by the following steps: a square magnet is placed directly below a beaker containing a solution of 1 mol / L nickel salt, and a nickel mesh is placed in the solution in a direction perpendicular to the magnetic field, sodium thiosulfate is added, and it is taken out after standing for 5-20 minutes. The nickel salt is consistent with that in step (1) of each embodiment. And sodium thiosulfate is added so that the pH of the mixed solution reaches 1-2.

[0035] Example 1

[0036] This Example 1 is based on an OER electrode of nickel-iron-based hydroxide, which is prepared by the following steps:

[0037] (1) a 46-mesh twill nickel wire mesh was cut into 24 rectangular pieces of 1 cm x 1 cm, and the pieces were cleaned with hydrochloric acid, acetone, deionized water and ethanol for 10 min in sequence to obtain a cleaned nickel wire mesh;

[0038] (2) depositing a nickel nitrate film layer on the surface of the cleaned nickel wire mesh;

[0039] (3) dissolving 30 parts of nickel nitrate hexahydrate and 30 parts of cobalt nitrate hexahydrate in 250 parts of deionized water to form solution A;

[0040] (4) dissolving 5 parts of tetrasodium ethylenediaminetetraacetate in 300 parts of deionized water to obtain solution B;

[0041] (5) dissolving 16.8 parts of ferrocenedicarboxylic acid and 11.2 parts of ferrocenylcarboxylic acid in 50 parts of N,N-dimethylformamide to obtain a solution C;

[0042] (6) adding solution A and solution C dropwise into solution B under vigorous stirring to obtain a mixed solution;

[0043] (7) The mixed solution and the cleaned nickel wire mesh were transferred to a 200 ml polytetrafluoroethylene container, heated at 200 ° C for 4 h, and then the product was taken out;

[0044] (8) The product was washed three times with deionized water and then dried in a vacuum oven at 60 °C for 12 h to obtain an OER electrode based on nickel-iron hydroxide.

[0045] Embodiment 2-6

[0046] The preparation method and parameter conditions are basically the same as those in Example 1, except for the differences in the substrates, as shown in Table 2.

[0047] Comparative Example 1

[0048] The preparation method and parameter conditions are basically the same as those in Example 1, except that the substrate is nickel foam with a pore size of 110 PPI.

[0049] Performance test 1: Voltage growth rate test

[0050] In the three-electrode test system, the potential-time measurement function was turned on and the current density was 1000A / m 2 The potential of the OER electrode was measured over time for 60 minutes, and the potential of the OER electrode was recorded. The average potential between 50 minutes and 60 minutes was used as the initial working potential of the OER electrode. In the two-electrode test system, the OER electrode was tested at 1000 A / m 2 Continue polarization for 1000h at the current density; measure the potential of the OER electrode after 1000h of polarization; the voltage growth rate formula is: V d =(V 1000 -V0) / V0×100%; V0—initial working potential, in volts (V); V 1000 —Potential after polarization for 1000 hours, in volts (V); V d —voltage growth rate, in percentage (%); the results are shown in Table 2.

[0051] Table 2 Voltage growth rate test of long-term polarization of OER electrodes of Examples 1-6 and Comparative Example 1

[0052] Example Base material Aperture(mesh / PPI) Twill / Straight Voltage growth rate (%) Example 1 Nickel wire mesh 46 mesh Twill 1.8％ Example 2 Nickel wire mesh 46 mesh Straight lines 2％ Example 3 Nickel wire mesh 40 mesh Twill 4.5％ Example 4 Nickel wire mesh 40 mesh Straight lines 5％ Example 5 Nickel wire mesh 60 mesh Twill 2.6％ Example 6 Nickel wire mesh 60 mesh Straight lines 3％ Comparative Example 1 Nickel Foam 110PPI / 9.7％

[0053] It can be seen from Table 2 that the nickel wire mesh has good corrosion resistance, can ensure the structural stability of the OER electrode during long-term polarization, and reduce the voltage growth rate of the OER electrode during long-term polarization. It can be seen from the comparison of Examples 1-6 that by using the nickel wire mesh as the base material and changing the mesh number and texture of the nickel wire mesh, the voltage growth rate is reduced from 5% to 1.8%; it can be seen from the comparison of Example 1 and Comparative Example 1 that by using a nickel foam with a pore size of 110 PPI as the base material, the voltage growth rate is increased from 1.8% to 9.7%.

[0054] Examples 7-12

[0055] This Example 7 is based on an OER electrode of nickel-iron-based hydroxide, and its preparation steps are basically the same as those of Example 1, except for the preparation of solution C, i.e., step (5). The specific differences are shown in Table 3 below.

[0056] Comparative Example 2

[0057] The OER electrode based on nickel-iron hydroxide of Comparative Example 2 is prepared by the following steps:

[0058] (1) Cut a 46-mesh twill nickel wire mesh into 24 rectangular blocks of 1 cm x 1 cm, and wash them with hydrochloric acid, acetone, deionized water, and ethanol for 10 minutes in sequence to obtain a cleaned nickel wire mesh;

[0059] (2) depositing a nickel nitrate film layer on the surface of the cleaned nickel wire mesh;

[0060] (3) dissolving 30 parts of nickel nitrate hexahydrate and 30 parts of cobalt nitrate hexahydrate in 250 parts of deionized water to form solution A;

[0061] (4) dissolving 5 parts of tetrasodium ethylenediaminetetraacetate in 300 parts of deionized water to obtain solution B;

[0062] (5) dissolving 28 parts of ferrocenedicarboxylic acid in 50 parts of N,N-dimethylformamide to obtain solution C;

[0063] (6) adding solution A and solution C dropwise into solution B under vigorous stirring to obtain a mixed solution;

[0064] (7) The mixed solution and the cleaned nickel wire mesh were transferred to a 200 ml polytetrafluoroethylene container, heated at 200 ° C for 4 h, and then the product was taken out;

[0065] (8) The product was washed three times with deionized water and then dried in a vacuum oven at 60 °C for 12 h to obtain an OER electrode based on nickel-iron hydroxide.

[0066] Comparative Example 3

[0067] The OER electrode based on nickel-iron-based hydroxide of Comparative Example 3 is prepared by the following steps:

[0068] (1) Cut a 46-mesh twill nickel wire mesh into 24 rectangular blocks of 1 cm x 1 cm, and wash them with hydrochloric acid, acetone, deionized water, and ethanol for 10 minutes in sequence to obtain a cleaned nickel wire mesh;

[0069] (2) depositing a nickel nitrate film layer on the surface of the cleaned nickel wire mesh;

[0070] (3) dissolving 30 parts of nickel nitrate hexahydrate, 30 parts of cobalt nitrate hexahydrate, and 24 parts of ferric nitrate nonahydrate in 300 parts of deionized water to form solution A;

[0071] (4) adding 20 parts of urea and 30 parts of aqueous ammonia to the mixed solution A to obtain a mixed solution B;

[0072] (5) The mixed solution B and the cleaned nickel wire mesh were transferred to a 200 ml polytetrafluoroethylene container, heated at 200 ° C for 4 h, and then the product was taken out;

[0073] (6) The product was washed three times with deionized water and then dried in a vacuum oven at 60 °C for 12 h to obtain an OER electrode based on nickel-iron hydroxide.

[0074] Performance test 2: Overpotential test

[0075] In the three-electrode test system, the potential-time measurement function was turned on and the current density was 1000A / m 2 The OER electrode potential was measured over time for 60 min, and the potential of the OER electrode was recorded. The average potential between 50 min and 60 min was taken as the initial working potential V0 of the OER electrode. The overpotential calculation formula is: η = |E 工作 -E0|×1000; η—overpotential, in millivolts (mV); E 工作 —Working potential after resistance compensation (vs.RHE), in volts (V); E0—theoretical electrode potential (vs.RHE), in volts (V); The results are shown in Table 3.

[0076] Table 3 Overpotential test of OER electrodes of Example 1, Examples 7-12 and Comparative Examples 2-3

[0077] Example Ferrocene dicarboxylic acid (parts) Ferrocene carboxylic acid (parts) Ferric nitrate nonahydrate (part) Overpotential(mV) Example 1 16.8 11.2 / 252 Example 7 14 14 / 254 Example 8 11.2 16.8 / 258 Example 9 8.4 19.6 / 263 Example 10 5.6 22.4 / 263 Embodiment 11 22.4 5.6 / 257 Example 12 19.6 8.4 / 255 Comparative Example 2 28 / / 267 Comparative Example 3 / / 24 283

[0078] As can be seen from Table 2, the surface of metal organic frameworks (MOFs) usually undergoes structural transformation to form metal hydroxides as catalytic active sites. As can be seen from the comparison between Example 1 and Examples 7-12, by mixing ferrocene dicarboxylic acid with defective ferrocene carboxylic acid ligands and changing the number of portions, a defective MOF with abundant unsaturated metal sites is constructed, so that the OER electrode contains more oxygen vacancies, which is beneficial to the adsorption of oxygen-containing intermediates in the active center, and exhibits excellent catalytic activity, with the overpotential reduced from 263mV to 252mV; As can be seen from the comparison between Example 1 and Comparative Examples 2-3, ferrocene dicarboxylic acid ligands or a mixture of ferrocene dicarboxylic acid and ferrocene carboxylic acid ligands are not used, and iron nitrate nonahydrate is directly used as Fe 3+ source, the overpotential increased to 267mV and 283mV respectively.

[0079] Examples 13-18

[0080] The steps of Examples 13 to 18 and Comparative Example 4 for the OER electrodes based on nickel-iron-based hydroxide are basically the same as those of Example 1, except for the selection of metal chelators, as shown in Table 4 below.

[0081] Performance test 3: Ultrasonic peeling test

[0082] The initial mass of three OER electrodes was weighed with an accuracy of 0.1 mg; the three electrodes were placed flat in three 250 mL glass beakers containing 200 mL of pure water, the beakers were placed in the middle of the ultrasonic instrument and fixed, water was added to the ultrasonic instrument until the water level in the inner tank was 50 mm, and then treated at a temperature of 30°C ± 1°C for 60 min; the test electrodes were taken out for cleaning and the final mass was weighed; the ultrasonic stripping rate formula is: M = (M0-M1) / M0×100%; M0—initial mass, in milligrams (mg); M1—final mass, in milligrams (mg); M—ultrasonic stripping rate, in percentage (%); the results are shown in Table 4.

[0083] Table 4 Ultrasonic peeling rate test of OER electrodes of Example 1, Examples 13-18 and Comparative Example 4

[0084] Example Metal Chelators Ultrasonic peeling rate (%) Example 1 Tetrasodium EDTA 0.08 Embodiment 15 Iminodisuccinic acid 0.12 Example 16 EDTA 0.13 Embodiment 17 Disodium EDTA 0.1 Embodiment 18 Hydroxyethylethylenediaminetriacetic acid 0.25 Embodiment 19 Diethylenetriaminepentaacetic acid 0.45 Embodiment 20 Citric acid 0.6 Comparative Example 4 / 2.85

[0085] From Table 4 and Figure 1It can be seen that the metal chelator tends to be adsorbed on the surface of the metal hydroxide, preventing it from aggregating and controlling the precipitation rate of the metal ions at the same time, and will not cause any phase segregation due to uncontrollable precipitation, thereby improving the uniformity of the catalyst layer; and under the chelating action of the metal chelator, the nickel-iron-based hydroxide formed by the nickel and iron in the solution can be tightly connected with the nickel salt layer film, thereby enhancing the bonding strength between the formed catalyst layer and the substrate material and reducing the ultrasonic stripping rate of the catalyst layer. It can be seen from the comparison between Example 1 and Examples 15-20 that by changing the type of metal chelator, the ultrasonic stripping rate is reduced from 0.6% to 0.08%; it can be seen from the comparison between Example 1 and Comparative Example 4 that by adding the metal chelator tetrasodium ethylenediaminetetraacetic acid, the ultrasonic stripping rate is reduced from 2.85% to 0.08%.

[0086] Comparative Example 5

[0087] The OER electrode based on nickel-iron hydroxide of Comparative Example 5 is prepared by the following steps:

[0088] (1) Cut a 46-mesh twill nickel wire mesh into 24 rectangular blocks of 1 cm x 1 cm, and wash them with hydrochloric acid, acetone, deionized water, and ethanol for 10 minutes in sequence to obtain a cleaned nickel wire mesh;

[0089] (2) depositing a nickel nitrate film layer on the surface of the cleaned nickel wire mesh;

[0090] (3) dissolving 30 parts of nickel nitrate hexahydrate and 30 parts of cobalt nitrate hexahydrate in 250 parts of deionized water to form solution A;

[0091] (4) dissolving 5 parts of tetrasodium ethylenediaminetetraacetate in 300 parts of deionized water to obtain solution B;

[0092] (5) dissolving 16.8 parts of ferrocenedicarboxylic acid and 11.2 parts of ferrocenylcarboxylic acid in 50 parts of -N,N-dimethylformamide to obtain a solution C;

[0093] (6) adding solution A and solution C dropwise into solution B under vigorous stirring to obtain a mixed solution;

[0094] (7) The mixed solution was transferred to a 200 ml polytetrafluoroethylene electrolytic cell, and a platinum sheet was used as the first working anode and a nickel wire mesh with a nickel nitrate film layer deposited on the surface was used as the first working cathode and inserted into the mixed solution. The distance between the first working anode and the first working cathode was 0.5 cm, and a current density of 0.3 A / dm was passed between the first working anode and the first working cathode. 2 The electrochemical deposition was carried out with a direct current of 20 min, and the product was taken out after the deposition was completed;

[0095] (8) The product was washed three times with deionized water and then dried in a vacuum oven at 60 °C for 12 h to obtain an OER electrode based on nickel-iron hydroxide.

[0096] Comparative Example 6

[0097] The OER electrode based on nickel-iron-based hydroxide of Comparative Example 6 is prepared by the following steps:

[0098] (1) Cut a 46-mesh twill nickel wire mesh into 24 rectangular blocks of 1 cm x 1 cm, and wash them with hydrochloric acid, acetone, deionized water, and ethanol for 10 minutes in sequence to obtain a cleaned nickel wire mesh;

[0099] (2) depositing a nickel nitrate film layer on the surface of the cleaned nickel wire mesh;

[0100] (3) dissolving 30 parts of nickel nitrate hexahydrate and 30 parts of cobalt nitrate hexahydrate in 250 parts of deionized water to form solution A;

[0101] (4) dissolving 5 parts of tetrasodium ethylenediaminetetraacetate in 300 parts of deionized water to obtain solution B;

[0102] (5) dissolving 16.8 parts of ferrocenedicarboxylic acid and 11.2 parts of ferrocenylcarboxylic acid in 50 parts of N,N-dimethylformamide to obtain a solution C;

[0103] (6) adding solution A and solution C dropwise into solution B under vigorous stirring to obtain a mixed solution;

[0104] (7) The mixed solution was transferred into a 200 ml polytetrafluoroethylene container, heated at 200 °C for 4 h, and then the product was taken out;

[0105] (8) Collecting the product by centrifugation to obtain a centrifuged product; washing the centrifuged product with deionized water for three times, and then drying it in a vacuum oven at 60°C for 12 hours, and then uniformly mixing it with 5 parts of a mixed solution of Nafion solution and ethanol solution with a volume ratio of 1:40 to form a catalyst binder mixture, brushing the catalyst binder mixture onto a nickel wire mesh and air-drying it until the liquid does not drip, and brushing it again after air-drying, and repeating the operation for 5 times to obtain a sample; placing the obtained sample in a muffle furnace and calcining it at 500°C for 3 hours to obtain an OER electrode based on nickel-iron hydroxide.

[0106] Performance test 4: Reverse current resistance test

[0107] In the three-electrode test system, the potential-time measurement function was turned on and the current density was 1000A / m 2The potential of the OER electrode was measured over time for 60 minutes, and the potential of the OER electrode was recorded. The average value of the potential between 50 minutes and 60 minutes was used as the initial working potential of the OER electrode. In the two-electrode test system, the current step method was started to test the OER electrode at 3000 A / m in a single cycle. 2 After positive polarization for 10 min at a current density of 300 A / m 2 Reverse polarization was performed for 10 min at a current density of 1000 times, and the working potential of the OER electrode in the second cycle and the 1000th cycle, and the overpotential of the OER electrode after the reverse current resistance test were recorded; after the reverse current resistance test, the potential change formula was: ΔE = |E 1000 -E0|×1000; ΔE—potential change after 1000 cycles of reverse current resistance test, in millivolts (mV); E0—overpotential before reverse current resistance test, in volts (V); E 1000 —Overpotential after the reverse current resistance test, in volts (V). The results are shown in Table 5.

[0108] Table 5 Reverse current resistance test of OER electrodes of Example 1 and Comparative Examples 5-6

[0109] Example Synthesis route Potential change (mV) Example 1 Hydrothermal One-step 0.026 Comparative Example 5 Electrochemical deposition 0.074 Comparative Example 6 Hydrothermal and then calcination 0.256

[0110] It can be seen from Table 5 that the hydrothermal one-step method is to perform a hydrothermal reaction on a solution containing active components and a conductive substrate material. It can be seen from the comparison between Example 1 and Comparative Examples 5-6 that the catalytic layer is directly formed on the substrate material by in-situ growth, which can reduce the resistance when the charge passes through and realize rapid charge transfer, thereby reducing the potential change of the OER electrode after the reverse current resistance performance test and enhancing the stability of the OER electrode. After the reverse current resistance performance test, the potential change of the OER electrode is 0.026mV.

[0111] In addition to the above embodiments, it should be noted that the following preparation steps of the alkaline OER electrode of the present invention are:

[0112] (1) dissolving 30-60 parts of a nickel salt and 0-30 parts of a cobalt salt in deionized water to prepare a solution A; the nickel salt may be nickel chloride or nickel acetate, and the cobalt salt may be cobalt chloride or cobalt acetate; preferably, the amount of the cobalt salt added may be 30 parts, and the amount of the deionized water may preferably be 250-400 parts;

[0113] (2) dissolving the metal chelating agent in deionized water to prepare solution B; preferably, the deionized water may be 300-400 parts;

[0114] (3) dissolving ferrocenyl dicarboxylic acid and ferrocenyl carboxylic acid in an organic solvent to prepare a solution C; the amount of ferrocenyl dicarboxylic acid added is preferably 5.6-22.4 parts, and the amount of ferrocenyl carboxylic acid added is preferably 5.6-22.4 parts; the organic solvent is preferably 50 parts, and can also be methanol or ethylene glycol;

[0115] (3) adding solution A and solution C to solution B to prepare a mixed solution;

[0116] (4) placing a nickel wire mesh substrate having a nickel salt layer on its surface into the mixed solution, and after hydrothermal reaction, washing and drying, an alkaline OER electrode based on nickel-iron hydroxide is obtained. The hydrothermal reaction may be heated at 120-200° C. for 4-12 hours, and the drying may be dried at 40-60° C. under vacuum for 12-24 hours.

[0117] That is, the technical effects claimed by the present invention can be achieved by adopting the preparation process of the present invention and the specified parameter range, and thus no further examples are given to illustrate the above.

Claims

1. An alkaline OER electrode based on nickel-iron hydroxide, characterized in that The alkaline OER electrode is prepared by the following steps: (1) dissolving 30-60 parts of nickel salt and 0-30 parts of cobalt salt in deionized water to prepare solution A; (2) dissolving the metal chelator in deionized water to prepare solution B; (3) dissolving 5.6-30 parts of ferrocenedicarboxylic acid and 5.6-30 parts of ferrocenylcarboxylic acid as iron salt in an organic solvent to prepare a solution C; (4) adding solution A and solution C to solution B to prepare a mixed solution; (5) A nickel wire mesh substrate with a nickel salt layer on its surface is placed in a mixed solution, and after hydrothermal reaction, washing and drying, an alkaline OER electrode based on nickel-iron hydroxide is prepared.

2. The alkaline OER electrode based on nickel-iron hydroxide according to claim 1, characterized in that In step (1), the amount of deionized water added is 0-400 parts.

3. The alkaline OER electrode based on nickel-iron hydroxide according to claim 1, characterized in that In step (1), the nickel salt is nickel nitrate hexahydrate, nickel chloride or nickel acetate; the cobalt salt is cobalt nitrate hexahydrate, cobalt chloride or cobalt acetate.

4. The alkaline OER electrode based on nickel-iron hydroxide according to claim 1, characterized in that In step (2), the metal chelating agent includes at least one of tetrasodium ethylenediaminetetraacetate, iminodisuccinic acid, ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetate, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid or citric acid.

5. The alkaline OER electrode based on nickel-iron hydroxide according to claim 1 or 4, characterized in that The weight proportion of the metal chelating agent is 5-10 parts, and the weight proportion of deionized water is 0-400 parts.

6. The alkaline OER electrode based on nickel-iron hydroxide according to claim 1, characterized in that In step (3), the organic solvent is N,N-dimethylformamide, methanol or ethylene glycol, and its content is 10-50 parts.

7. The alkaline OER electrode based on nickel-iron hydroxide according to claim 1, characterized in that In step (4), the nickel wire mesh is a straight or twill nickel wire mesh with a mesh size of 40-60.

8. The alkaline OER electrode based on nickel-iron hydroxide according to claim 1, characterized in that In step (4), the nickel wire mesh substrate with a nickel-based layer on the surface is prepared by the following steps: a square magnet is placed directly below a beaker containing a solution of 0.5-1.5 mol / L nickel salt, and the nickel mesh is placed in the solution in a direction perpendicular to the magnetic field, an oxidizing and reducing agent is added, and the solution is taken out after standing for 5-20 minutes.

9. The alkaline OER electrode based on nickel-iron hydroxide according to claim 8, characterized in that The redox agent is sodium thiosulfate or hydrazine hydrate.

10. The alkaline OER electrode based on nickel-iron hydroxide according to claim 1, characterized in that: In step (4), the hydrothermal reaction is carried out at 120-200° C. for 4-12 h; and the drying is carried out at 40-60° C. under vacuum for 12-24 h.

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