Alkaline electrolytic water hydrogen production electrode, preparation method, application and catalyst system

Abstract

The invention relates to the technical field of water electrolysis hydrogen production electrodes, in particular to an alkaline water electrolysis hydrogen production electrode, a preparation method, application and a catalyst system. The alkaline water electrolysis hydrogen production electrode comprises a conductive substrate, and a pointed cone array structure containing nickel or nickel alloy is formed on the surface of the conductive substrate through magnetic field auxiliary electro-deposition; the pointed cone array structure comprises a first-stage pointed cone array located on the bottom layer and a second-stage pointed cone array growing on the surface of the first-stage pointed cone array, and the height-width ratio of the pointed cone array structure is 2-6: 1. The alkaline water electrolysis hydrogen production electrode has excellent catalytic activity, has the characteristics of high efficiency, stability and easiness in industrialization, can be used as the alkaline water electrolysis hydrogen production electrode, and can stably work for a long time under high current.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production electrodes, and particularly to an alkaline water electrolysis hydrogen production electrode, a preparation method, an application, and a catalyst system. Background Art

[0002] Alkaline water electrolysis is a key technology for producing green hydrogen. Due to its mild operating conditions, low cost, and the absence of the need for precious metal catalysts, it has a wide range of applications in the industrial field. However, existing electrolytic water catalysis technologies face many bottlenecks at high current densities. First, the overpotential of the oxygen evolution reaction (OER) during water electrolysis is relatively high, resulting in low energy utilization efficiency. This is mainly due to the limited number of active sites on the catalyst surface and the limitation of surface electron transfer kinetics. Second, as the electrolysis current density increases, a large number of bubbles will be generated near the reaction interface. These bubbles adhere to the electrode surface, hindering the contact between the electrolyte and the electrode, and further reducing the catalytic performance. In addition, the mechanical stability of traditional catalysts is insufficient during long-term operation, and the electrode structure is prone to collapse or exfoliation due to stress and chemical corrosion, thus limiting its lifespan. Existing research attempts to improve the catalyst performance by designing micro-nano structures, such as using porous structures or nanoarrays to increase the specific surface area. However, these structures are difficult to effectively manage the generation and release of bubbles at high current densities, resulting in low mass transfer efficiency.

[0003] The catalytic performance of electrolytic water catalysts is closely related to their synthesis and preparation conditions. Traditional methods such as chemical deposition have problems such as complex steps, uneven composition, and easy introduction of impurities, which are not conducive to industrial applications. Plasma spraying and conventional electrochemical deposition can obtain relatively simple pore structures and pore size structures with low surface areas, which are not conducive to the performance of catalytic electrodes. Therefore, it is particularly important to develop a catalyst material with a high density of active sites, excellent bubble management ability, and long-term mechanical stability. Summary of the Invention

[0004] The present application provides an alkaline water electrolysis hydrogen production electrode, a preparation method, an application, and a catalyst system. The present invention uses magnetic field-assisted electrodeposition to form a multi-level tapered array structure, which has excellent catalytic activity, can significantly improve the efficiency of the oxygen evolution reaction (OER) at high current densities, and has excellent stability, suitable for industrial-scale water electrolysis hydrogen production applications.

[0005] The object of the present invention is achieved by the following technical solutions:

[0006] The first object of the present application is to provide an alkaline water electrolysis hydrogen production electrode, including a conductive substrate, and a tapered array structure containing nickel or nickel alloy is formed on the surface of the conductive substrate by magnetic field-assisted electrodeposition;

[0007] The tapered array structure includes a primary tapered array at the bottom layer and a secondary tapered array grown on its surface.

[0008] Furthermore, the aspect ratio of the primary tapered array is 2 - 4:1, and the aspect ratio of the secondary tapered array is 4 - 6:1.

[0009] Furthermore, an electroplating solution for forming a tapered array structure containing nickel or nickel alloy is provided. In each liter of the electroplating solution, the following raw materials are included:

[0010] 0.1 - 1 mol of metal ions; nickel salt; H3BO3; NH4Cl;

[0011] The molar ratio of metal ions, nickel salt, H3BO3, and NH4Cl is 1:0.2 - 1.2:0.2 - 1.2:0.5 - 5.0.

[0012] Furthermore, the metal ions are selected from one or more of iron salts, cobalt salts, molybdates, tungstates, gold salts, and copper salts.

[0013] Furthermore, the nickel salt is one or more of nickel chloride, nickel nitrate, nickel acetate, nickel sulfate, nickel oxalate, nickel perchlorate, nickel chlorate, and nickel bromide; the iron salt is one or more of ferric chloride, ferrous chloride, ferrous nitrate, ferric sulfate, ferrous sulfate, ferric oxalate, ferrous oxalate, ferric acetate, ferric perchlorate, ferrous chlorate, ferrous acetate, and ferric bromide; the cobalt salt is one or more of cobalt chloride, cobalt nitrate, cobalt sulfate, cobalt oxalate, cobalt chlorate, cobalt perchlorate, and cobalt acetate; the molybdate is one or more of sodium molybdate, ammonium molybdate, molybdic acid, and molybdenyl chloride; the tungstate is one or more of ammonium tungstate, sodium tungstate, potassium tungstate, and lithium tungstate; the gold salt is one or more of chloroauric acid, potassium aurocyanide, bromoauric acid, and gold thiosulfate; the copper salt is one or more of copper sulfate, copper chloride, copper nitrate, copper cyanide, and copper acetate.

[0014] Furthermore, for the nickel alloy of the tapered array structure, the chemical composition of the nickel alloy is selected from any one of the following chemical formulas Ni 100-x Z x , where Z is a metal element and x is between 1 and 5;

[0015] Ni 100-x Fe x , where x is between 5 and 25;

[0016] Ni 100-x Co x , where x is between 5 and 25;

[0017] Ni 100-x Mo x , where x is between 5 and 25;

[0018] Ni 100-x W x , x is between 5 and 25;

[0019] Ni 100-x Au x , x is between 5 and 25;

[0020] Ni 100-x Cu x , x is between 5-25.

[0021] The second object of the present application is to provide a method for preparing an alkaline water electrolysis hydrogen production electrode, comprising the following steps:

[0022] S1. Preparation of plating solution:

[0023] The nickel salt, metal ions, H3BO3, NH4Cl and water are fully mixed, and the pH is adjusted to 3.5-4.5 to obtain an electroplating solution;

[0024] S2. Magnetic field assisted electrodeposition:

[0025] An inert conductor is used as the anode and a conductive substrate is used as the cathode; a magnetic field perpendicular to the substrate surface is applied to uniformly cover the entire electrolysis area; a DC power supply or a pulse power supply is used for electrodeposition, wherein the magnetic field intensity B(t) is calculated according to the formula B(t)=B0+(B f -B0)(t / T) α Dynamic adjustment, where t is the moment in the deposition process, T is the total deposition time, B0 is the initial magnetic field strength, and B f is the final magnetic field strength, α is the regulation index;

[0026] S3. Post-processing:

[0027] After the electrodeposition is completed, the conductive substrate is taken out, cleaned and dried to obtain an electrode with a nickel alloy multi-level pointed cone structure.

[0028] Further, in step S2, during the deposition process, the deposition process sequentially undergoes three stages: early stage, middle stage and late stage. In the early stage, the magnetic field strength is 100-1000 Gs and the current density is 20-30 mA / cm 2 In the medium term, the magnetic field strength is 1000-5000Gs and the current density is 30-50mA / cm 2 In the later stage, the magnetic field strength is maintained in the medium term and the current density is adjusted to 20-30mA / cm 2 , forming a multi-level pointed cone structure.

[0029] The third purpose of the present application is to provide an application of an alkaline water electrolysis hydrogen production electrode, and to apply the above-mentioned alkaline water electrolysis hydrogen production electrode to the field of water electrolysis.

[0030] The fourth objective of the present application is to provide a catalyst system for preparing an alkaline electrolytic water hydrogen production electrode, which is used to prepare the above-mentioned alkaline electrolytic water hydrogen production electrode and includes:

[0031] A vertically installed electromagnetic coil or permanent magnet array for providing a vertical magnetic field of 100 - 5000 Gs;

[0032] An electroplating tank for loading electroplating solution and completing the electroplating of a conductive substrate;

[0033] A temperature control unit for controlling the temperature of the electroplating solution within the range of 30 - 80 °C;

[0034] A power supply module for providing a direct current of 20 - 50 mA / cm 2 of.

[0035] The beneficial effects of the present invention are as follows:

[0036] The beneficial effects of the present invention are:

[0037] 1. Ion distribution control and structure optimization. The present invention adopts an externally applied magnetic field-assisted electroplating technology to precisely regulate the deposition path of metal ions and the directional growth of the cone structure through the Lorentz force generated by the magnetic field, effectively reducing the problem of uneven ion distribution in traditional electroplating methods. By optimizing the electroplating solution formula, precise control of the composition and morphology of the cone structure can be achieved, thereby providing a low-cost and high-performance catalyst preparation method.

[0038] 2. High activity and high stability. The multi-stage cone structure of the present invention has the following characteristics: abundant high-index crystal planes and line defects, significantly increasing the specific surface area and providing more active sites for electrocatalytic reactions; a uniformly dense nickel alloy active oxide layer is formed on the surface, enhancing the chemical stability of the catalyst; the secondary cone array further improves the ion conduction ability and reduces the energy barriers of the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER); the secondary structure of the cone array helps to enhance the ion conduction ability, and the alloy itself in the cone structure has a relatively excellent adsorption energy for oxygen evolution reaction intermediates, and the alloy in-situ grown on the conductive substrate has good electrical conductivity.

[0039] 3. Bubble Management and Reaction Rate Optimization. Through the unique design of the multi-level tapered structure, the present invention provides an innovative bubble management strategy: the aspect ratio of the tapered structure optimizes the hydrophilic and hydrophobic properties of the electrode surface, effectively reducing the problem of bubble retention; the tip electric field effect accelerates the transport of electrolyte ions, further improving the reaction kinetics performance. The nickel alloy multi-level tapered structure with a multi-level structure not only has ultra-high electrocatalytic activity at low currents but also excellent electrocatalytic activity at high current densities. Moreover, due to the rich surface morphology of the tapered structure, when the alkaline water electrolysis hydrogen production electrode is used as the anode, the alloy oxide layer and the metal single layer can maintain their original state. When the alkaline water electrolysis hydrogen production electrode is used as the cathode, the multi-level tapered structure significantly reduces the energy barrier of the hydrogen evolution reaction by increasing the local electric field strength, and the tapered structure itself has good mechanical stability. Therefore, it has both chemical stability and mechanical stability.

[0040] 4. Industrial Applicability. The present invention combines the magnetic field-assisted electrodeposition technology with the tapered structure design, innovatively solving the problems of insufficient activity and poor stability of traditional electrodes at high current densities. The electrode of the present invention can still maintain stable catalytic performance at high current densities (200 - 1000 mA / cm 2 ), indicating its good mechanical and chemical stability and suitability for long-term service. By changing the composition of the electroplating solution and the magnetic field conditions, the morphology and composition of the tapered structure can be flexibly adjusted, significantly reducing the preparation cost and providing the possibility for large-scale industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be further described below with reference to the drawings and embodiments.

[0042] Figure 1 is the scanning electron microscope (SEM) image of the alkaline water electrolysis hydrogen production electrode prepared in Example 1 of the present invention;

[0043] Figure 2 is Figure 1 the partial enlarged view;

[0044] Figure 3 are the element distribution maps (EDX) of the X-ray energy spectrum analysis of the primary nickel-iron nano-tapered array of the alkaline water electrolysis hydrogen production electrode prepared in Example 1 of the present invention;

[0045] Figure 4 are the element distribution maps of the X-ray energy spectrum analysis of the secondary nickel-iron nano-tapered array of the alkaline water electrolysis hydrogen production electrode prepared in Example 1 of the present invention;

[0046] Figure 5 is the linear sweep voltammetry (LSV) curve of the alkaline water electrolysis hydrogen production electrode prepared in Example 1 of the present invention;

[0047] Figure 6 It is the linear sweep voltammetry (LSV) curve graph of the alkaline electrolyzed water hydrogen production electrode prepared in Example 2 of the present invention;

[0048] Figure 7 It is the scanning electron microscopy (SEM) image of the alkaline electrolyzed water hydrogen production electrode prepared in Example 1 of the present invention after the oxygen evolution reaction (OER) at a current density of 1000 mA / cm 2 ;

[0049] Figure 8 It is the contact angle test graph of the alkaline electrolyzed water hydrogen production electrode prepared in Example 1 of the present invention. Detailed implementation manners

[0050] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. As used herein, the singular forms "a", "an", "one" and "the" are also intended to include the plural forms unless the context clearly indicates otherwise. Further understanding, when "including" is used in this specification, it specifies the stated features, integers, steps, operations, elements and / or components, but does not exclude the existence or addition of one or more other features, integers, steps, operations, elements, components and / or their combinations.

[0051] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. Further understanding, terms, such as those defined in a common dictionary, are interpreted to be consistent with their meanings in the context of the relevant field and are not in an idealized or overly formal sense unless clearly defined as such herein.

[0052] The exemplary inventions described herein may appropriately lack any one or more of the element limitations that are not specifically disclosed herein. Therefore, terms such as "comprising", "including", "containing", etc. should be understood broadly and non-restrictively. Additionally, the terms of expression used herein are used for description without limitation, and it is not intended that these terms of expression that do not include any equivalent features only describe a part of their features, but various modifications are possible within the scope of the present invention according to the claims. Therefore, although the present invention has been specifically disclosed through preferred embodiments and optional features, modifications to the present invention as embodied herein may be recorded by those skilled in the art, and such modifications and variations will be considered to be within the scope of the present invention.

[0053] The raw materials or reagents used in the embodiments and comparative examples of the present invention are all purchased from mainstream manufacturers in the market. For those without specified manufacturers or concentrations, they are raw materials or reagents of analytical purity grade that can be obtained conventionally. As long as they can play the expected role, there are no special restrictions. The reaction, stirring and other instrument equipment used in this embodiment are all purchased from major manufacturers in the market. As long as they can play the expected role, there are no special limitations. For those without specified specific technologies or conditions in this embodiment, they are carried out according to the technologies or conditions described in the literature in this field or according to the product instructions.

[0054] To provide an alkaline electrolytic water hydrogen production electrode, preparation method, application and catalyst system that can significantly improve the efficiency of the oxygen evolution reaction (OER) at a high current density and have excellent stability at the same time.

[0055] The alkaline electrolytic water hydrogen production electrode includes a conductive substrate, and a nickel-containing or nickel alloy conical array structure is formed on the surface of the conductive substrate by magnetic field-assisted electrodeposition; the conical array structure includes a primary conical array at the bottom layer and a secondary conical array growing on its surface, and the aspect ratio of the conical array structure is 2-6:1. ("Width" refers to the widest part of the cone, that is, the junction of the cone and the conductive substrate).

[0056] Specifically, the aspect ratio of the primary conical array is 2-4:1, and the aspect ratio of the secondary conical array is 4-6:1.

[0057] Among them, the electroplating solution for forming a nickel-containing or nickel alloy conical array structure contains the following raw materials per liter of the electroplating solution:

[0058] 0.1-1 mol of metal ions; nickel salt; H3BO3; NH4Cl;

[0059] The molar ratio of metal ions, nickel salt, H3BO3, and NH4Cl is 1:0.2-1.2:0.2-1.2:0.5-5.0.

[0060] The metal ions are from one or more of iron salts, cobalt salts, molybdates, tungstates, gold salts, and copper salts.

[0061] The nickel salt is one or more of nickel chloride, nickel nitrate, nickel acetate, nickel sulfate, nickel oxalate, nickel perchlorate, nickel chlorate, nickel bromide; the iron salt is one or more of ferric chloride, ferrous chloride, ferrous nitrate, ferric sulfate, ferrous sulfate, ferric oxalate, ferrous oxalate, ferric acetate, ferric perchlorate, ferrous chlorate, ferrous acetate, ferric bromide; the cobalt salt is one or more of cobalt chloride, cobalt nitrate, cobalt sulfate, cobalt oxalate, cobalt chlorate, cobalt perchlorate, cobalt acetate; the molybdate is one or more of sodium molybdate, ammonium molybdate, molybdic acid, oxomolybdenum chloride; the tungstate is one or more of ammonium tungstate, sodium tungstate, potassium tungstate, lithium tungstate; the gold salt is one or more of chloroauric acid, potassium aurocyanide, bromoauric acid, gold thiosulfate; the copper salt is one or more of copper sulfate, copper chloride, copper nitrate, copper cyanide, copper acetate.

[0062] Among them, for the nickel alloy with a tapered array structure, the chemical composition of the nickel alloy is selected from any one of the following chemical formulas Ni100-xZx, where Z is a metal element and x is between 1 and 5;

[0063] Ni100-xFex, where x is between 5 and 25;

[0064] Ni100-xCox, where x is between 5 and 25;

[0065] Ni100-xMox, where x is between 5 and 25;

[0066] Ni100-xWx, where x is between 5 and 25;

[0067] Ni100-xAux, where x is between 5 and 25;

[0068] Ni100-xCux, where x is between 5 and 25.

[0069] Preferably, the nickel alloy is Ni 83 Fe 17 、Ni 85 Co 15 、Ni 80 Mo 20 any one of them.

[0070] Among them, the conductive substrate is any one of a stainless steel sheet, a stainless steel mesh, a stainless steel foam, a stainless steel wire, a fiber cloth, a nickel sheet, a nickel mesh, a molybdenum mesh, a nickel foam, a titanium sheet, a titanium mesh, a titanium fiber, an iron mesh nickel foil, a copper foil, a copper mesh, a copper foam.

[0071] The stainless steel sheet can be selected as SUS304, SUS316, SUS316L, SUS430, with a thickness of 0.05 mm - 2 mm and an area of 10 mm * 10 mm - 100 mm * 100 mm;

[0072] The stainless steel mesh can be selected from SUS316L and SUS304, with a mesh number of 40-200 meshes, a wire diameter of 0.1mm-0.5mm, a thickness of 0.5mm-1.5mm, and an area of ​​25mm*25mm-100mm*100mm;

[0073] The stainless steel foam can be selected as SUS316L, with a porosity of 60%-99%, a pore size of 50μm-1mm, and a thickness of 1mm-3mm;

[0074] The stainless steel wire or fiber cloth can be selected from SUS316L and SUS310S, with a fiber diameter of 10μm-50μm, a thickness of 0.1mm-0.5mm, and an area of ​​10mm*10mm-100mm*100mm.

[0075] The surface of each alloy cone is covered with a secondary cone array of metal, metal hydroxide or metal oxide by electrodeposition. The surface structure of the secondary alloy cone array can increase active sites, improve electronic conductivity or enhance chemical stability, thereby significantly improving its effect as a catalyst.

[0076] The thickness of the surface structure ranges from 1 to 50 nanometers, preferably from 5 to 25 nanometers, to ensure good electrocatalytic performance.

[0077] The above-mentioned method for preparing an alkaline water electrolysis hydrogen production electrode comprises the following steps:

[0078] S1. Preparation of plating solution:

[0079] The electroplating solution is heated to 30-80° C., preferably 50-60° C., the nickel salt, metal ions, H3BO3, NH4Cl and water are fully mixed, and the pH is adjusted to 3.5-4.5 with HCl to obtain an electroplating solution;

[0080] S2. Magnetic field assisted electrodeposition:

[0081] Using an inert conductor as the anode and a conductive substrate as the cathode; inserting them into the electroplating solution to ensure full contact between the substrate surface and the solution. During the electrodeposition process, an external magnetic field is applied to ensure that the magnetic field direction is perpendicular to the substrate surface and uniformly covers the entire electrolysis area. Through the action of the magnetic field, the deposition behavior of metal ions is regulated, thereby optimizing the structure and properties of the deposited layer. First, deposit a primary array on the conductive substrate, and then deposit a secondary array on the surface of the primary array. Dynamically adjust the magnetic field intensity as needed. Specifically, at the initial stage of deposition, a lower magnetic field intensity can be used to promote uniform nucleation; in the middle stage of deposition, gradually increase the magnetic field intensity and adjust the magnetic field direction (for example, forming an angle of 80° - 100° with the ion deposition direction) to regulate the ion movement trajectory and optimize the microstructure of the deposited layer; in the later stage of deposition, maintain the magnetic field intensity and direction in the middle stage of deposition to ensure the density and functionality of the deposited layer. Use a DC power supply or a pulse power supply to control the electrodeposition process. With the assistance of a perpendicular magnetic field, ion migration is affected by the Lorentz force, forming a multi-level conical morphology;

[0082] S3. Post-treatment:

[0083] After the electrodeposition is completed, take out the conductive substrate, clean and dry it to avoid oxidation, and obtain an electrode with a nickel alloy multi-level conical structure.

[0084] Among them, in step S2, the angle between the magnetic field direction and the metal ion deposition direction is 60° - 120°;

[0085] The magnetic induction intensity is between 100 Gs - 5000 Gs;

[0086] The current density is (10 - 50 mA / cm 2 ).

[0087] In step S2, during the deposition process, the magnetic induction intensity and the current density can be selected to remain constant or be dynamically adjusted according to the requirements of the deposition stage. To achieve precise control of the ion trajectory, the present invention introduces a dynamic adjustment strategy, the core of which can be through the Lorentz force formula:

[0088] F = q(v × B)

[0089] Combined with the ion motion equation to establish a mathematical model to predict and regulate the ion motion trajectory. To further achieve dynamic adjustment, the present invention provides a regulation formula for the magnetic field intensity varying with the deposition time. Let the total deposition time be T, and the magnetic field intensity B(t) at any moment t (0 ≤ t ≤ T) during the deposition process can be expressed as:

[0090] B(t) = B0 + (B f - B0)(t / T) α

[0091] Among them, B0 is the magnetic field intensity used at the initial stage of deposition, Bf $B$ is the magnetic field strength adopted in the late deposition stage, and $\alpha$ is the regulation index (for example, when $\alpha = 1$, it is a linear change; when $\alpha>1$, it represents an accelerated change; when $\alpha<1$, it represents a decelerated change).

[0092] Meanwhile, the present invention can achieve phased dynamic regulation during the deposition processes of both the primary tapered array and the secondary tapered array, that is, during the pre-deposition, mid-deposition, and late-deposition stages of each, it not only meets the basic requirements of the magnetic field and current density but also makes fine adjustments to the parameters according to the different requirements of nucleation, structural growth, and densification optimization. The pre-deposition stage refers to the substrate growth stage of the primary tapered array, the mid-deposition stage refers to the screw dislocation longitudinal growth of the primary tapered array and the substrate growth stage of the secondary tapered array, and the late-deposition stage refers to the screw dislocation longitudinal growth stage of the secondary tapered array. For example, during the deposition process, in the early stage, a magnetic field of 100 Gs to 1000 Gs and a current density of 20 to 30 mA / cm 2 are adopted to promote uniform nucleation; in the mid-stage, the magnetic field strength is gradually increased to 1000 Gs to 5000 Gs, and the current density is adjusted to 30 to 50 mA / cm 2 to optimize the ion movement trajectory; in the late stage, the magnetic field strength and direction in the mid-stage are maintained, and the current density is adjusted to 20 to 30 mA / cm 2 to ensure the densification of the tapered array.

[0093] Through the above time-based dynamic regulation formula and phased parameter adjustment strategy, the present invention realizes the precise control of the magnetic field on the ion deposition trajectory, further optimizes the electrode surface structure, and improves the electrocatalytic activity and long-term stability.

[0094] Higher magnetic induction intensity and current density usually lead to a more significant Lorentz force effect, thereby promoting the longitudinal growth of the tapered structure and increasing the aspect ratio; while lower parameters tend to form a more uniform structure with a lower aspect ratio. For the secondary array, the dynamic regulation of the magnetic induction intensity and current density is particularly important because they directly affect the morphology and distribution uniformity of the secondary tapered tips, and thus affect the catalytic performance or functionality of the overall array.

[0095] Specifically, the distance between the two poles of the magnetic field is 15 - 20 cm, and a uniform magnetic field of 100 Gs to 5000 Gs is applied, and the preferred magnetic field strength range is 200 - 2000 Gs. The angle between the direction of this magnetic field and the metal ion deposition direction is 60° - 120°, preferably 80° - 100°.

[0096] Among them, the distance between the first working anode and the first working cathode is 1 - 2 cm, and a current density of 20 - 50 mA / cm 2Direct current is used for electrochemical deposition at 30 - 80 °C for 15 - 30 minutes. After the deposition is completed, the conductive substrate is taken out, rinsed with deionized water, and dried in an oven to obtain an alkaline electrolytic water hydrogen production electrode with a multi-level tapered structure on its surface.

[0097] For the convenience of those skilled in the art, the present invention will be further described below in conjunction with embodiments. The content mentioned in the embodiments does not limit the present invention.

[0098] Example 1

[0099] A preparation method of an alkaline electrolytic water hydrogen production electrode includes the following steps:

[0100] (1) Treat the conductive substrate

[0101] Select a SUS304 stainless steel sheet with a thickness of 1 mm and cut it into a sheet with a size of 2 cm × 2 cm. Put the cut stainless steel sheet into a 2 mol / L HCl solution and perform ultrasonic treatment for 5 minutes to remove the oxide layer on its surface. After treatment, wash it with deionized water and ethanol and dry it naturally in the air.

[0102] (2) Prepare the electroplating solution

[0103] Prepare a mixed solution with 0.84 M NiCl2·6H2O, 0.39 M FeCl, 0.65 M H3BO3, and 1.86 M NH4Cl, and stir it magnetically for 20 - 40 minutes to make it fully mixed. Subsequently, adjust the pH value of the electroplating solution to 3.0 - 5.0, and after mixing evenly, place the solution in a water bath at 30 - 80 °C for heating.

[0104] (3) Electrochemical deposition under magnetic field assistance

[0105] Adjust the prepared electroplating solution to pH 3.5 - 4.5, use a platinum sheet as the first working anode, and the conductive substrate treated in step (1) as the first working cathode, and insert them into the electroplating solution. The distance between the first working anode and the first working cathode is 1.5 cm, and a direct current with a current density of 20 mA / cm 2 is passed, and a uniform vertical magnetic field of 300 Gs is applied. The electro-deposition process is carried out at 50 °C for 15 minutes, and finally a multi-level tapered structure containing nickel-iron alloy is formed on the surface of the conductive substrate.

[0106] (4) Post-treatment. After the electro-deposition is completed, take out the conductive substrate and rinse it three times with deionized water. Then, place it in an oven at 50 °C and dry it for 1 hour to obtain a nickel-iron electrode with a multi-level tapered structure on its surface. This electrode can be used as an alkaline electrolytic water hydrogen production electrode and exhibits excellent oxygen evolution performance.

[0107] Among them, the morphology of the multi-level nickel-iron cone electrode is as follows Figure 1 and Figure 2 As shown. The observation results show that the surface of the electrode presents a typical multi-level cone array morphology. Due to the magnetic field-assisted electrodeposition, the secondary nickel-iron cone array is deposited on the surface of the primary nickel-iron cone array to form a multi-level structure. When the electrode is used as an anode for oxygen evolution reaction, the exposed metal element and the oxide layer remain stable, and the cone morphology can concentrate the electric field, produce a local high concentration in the tip area, and then promote the kinetic process of the chemical reaction, thereby obtaining excellent catalytic performance.

[0108] To evaluate the electrochemical performance of the electrode, an electrochemical workstation was used to test it.

[0109] The electrochemical workstation CHI 660E was used to test the product. The electrolytic cell used a standard three-electrode system. The alkaline water electrolysis hydrogen production electrode was clamped with a platinum electrode as the working electrode, a graphite rod as the counter electrode, Hg / HgO as the reference electrode, and the electrolyte was a 1 mol / L KOH solution. The scanning rate of the linear sweep voltammogram (LSV) was 1 mV / s, the voltage was manually compensated by 98% iR, and the potential scanning range was 1.2-1.6 V. Figure 3 and Figure 4 It can be seen from the X-ray energy spectrum analysis diagram of the primary and secondary nickel-iron cones that Ni, Fe and O are evenly distributed on the surface of the cone, indicating that the deposition of the nickel-iron alloy is uniform and stable.

[0110] According to the formula: overpotential = actual measured potential + 0.059 × pH + 0.095V-1.23V, it is calculated that the electrode is 10mA / cm 2 and 250mA / cm 2 At current densities of , the oxygen evolution overpotentials are 199 mV and 256 mV respectively.

[0111] Compared with the control sample (pure nickel cone grown on nickel foam), at the same current density, the hydrogen evolution overpotential of the control sample is 211mV and 270mV, respectively, which is significantly lower than that of the multi-stage nickel-iron cone electrode, such as Figure 5 This indicates that the multi-level nickel-iron cone electrode prepared in this example has higher catalytic activity.

[0112] Example 2

[0113] The difference from Example 1 is that: a nickel foam with a thickness of 1.5 mm is selected, and a uniform vertical magnetic field with a magnetic field strength of 1000 Gs is used in step (3). The current density in step (3) is 30 mA / cm 2, the electro - deposition time was 20 min, and the deposition temperature was 60 °C. The conductive substrate served as the cathode, and the platinum sheet served as the anode. The distance between the two was 2 cm, and both were immersed in the electroplating solution. During the deposition process, the multi - level nickel - iron cone structure grew directionally on the surface of the conductive substrate. The remaining steps were the same as those in Example 1.

[0114] The obtained alkaline electrolytic water hydrogen - production electrode was subjected to the following electrochemical tests:

[0115] Using a CHI 660E electrochemical workstation, the electrochemical test of the electrode was carried out at room temperature. The electrolytic cell was a standard three - electrode system. The alkaline electrolytic water hydrogen - production electrode obtained in this example was clamped with a platinum electrode clip as the working electrode, the graphite rod as the counter electrode, and Hg / HgO as the reference electrode. The electrolyte was 1 mol / L KOH. The scanning rate of the linear sweep voltammogram (LSV) was 5 mV / s, and the voltage was manually compensated by 95% iR. According to the formula: over - potential = measured potential+0.059×pH + 0.095 V. The alkaline electrolytic water hydrogen - production electrode prepared in this example included a nickel - iron phosphide cone array loaded on nickel foam. After testing, the hydrogen - evolution over - potential of the alkaline electrolytic water hydrogen - production electrode obtained in this example was 81 mV, 241 mV, and 320 mV at the current densities of 10 mA / cm 2 、100 mA / cm 2 and 500 mA / cm 2 , showing excellent hydrogen - evolution catalytic activity.

[0116] Using the same method, pure nickel cones were grown on nickel foam as a control sample. The hydrogen - evolution over - potential at the current densities of 10 mA / cm 2 、100 mA / cm 2 and 500 mA / cm 2 was 95 mV, 264 mV, and 341 mV respectively; the performance of the control sample was inferior to that of the multi - level nickel - iron cones, as Figure 6 shown. The oxygen - evolution reaction (OER) test was carried out on the electrode of Example 1 at a current density of 1000 mA / cm 2 . After the test, the SEM results, as Figure 7 shown, showed that the morphology of the multi - level cones could be maintained intact, proving that the electrode had excellent structural stability. In addition, the contact - angle test diagram, as Figure 8 shown, indicated that the electrode surface had good wetting properties.

[0117] Example 3

[0118] The electroplating solution is prepared by mixing 0.84M NiCl2·6H2O, 0.39M FeCl, 0.65M H3BO3 and 1.86M NH4Cl, and magnetically stirred for 30 minutes to make them fully mixed. Subsequently, the pH value of the electroplating solution is adjusted to 4.0, and after mixing evenly, the solution is placed in a water bath at 50°C for heating.

[0119] A nickel sheet with a thickness of 1 mm is selected, and a uniform vertical magnetic field with a magnetic field intensity of 2000 Gs is used in step (3). The current density in step (3) is 50 mA / cm 2 , the electro-deposition time is 30 min, and the deposition temperature is 80°C. The conductive substrate serves as the cathode, and the platinum sheet serves as the anode. The distance between the two is 1 cm, and both are immersed in the electroplating solution. During the deposition process, the multi-stage nickel-iron cone structure grows directionally on the surface of the conductive substrate. The remaining steps are the same as those in Example 1.

[0120] The obtained alkaline electrolytic water hydrogen production electrode is subjected to the following electrochemical tests:

[0121] According to the formula: overpotential = actual measured potential + 0.059×pH + 0.095V - 1.23V, it is calculated that the oxygen evolution overpotential of this electrode is 89 mV and 281 mV respectively at the current densities of 10 mA / cm 2 and 250 mA / cm 2 .

[0122] Example 4

[0123] A uniform vertical magnetic field with a magnetic field intensity of 3000 Gs is used in step (3). The remaining steps are the same as those in Example 1.

[0124] The obtained alkaline electrolytic water hydrogen production electrode is subjected to the following electrochemical tests:

[0125] According to the formula: overpotential = actual measured potential + 0.059×pH + 0.095V - 1.23V, it is calculated that the oxygen evolution overpotential of this electrode is 91 mV and 288 mV respectively at the current densities of 10 mA / cm 2 and 250 mA / cm 2 .

[0126] Example 5

[0127] A uniform vertical magnetic field with a magnetic field intensity of 5000 Gs is used in step (3). The remaining steps are the same as those in Example 1.

[0128] The obtained alkaline electrolytic water hydrogen production electrode is subjected to the following electrochemical tests:

[0129] According to the formula: overpotential = actual measured potential + 0.059×pH + 0.095V - 1.23V, it is calculated that the oxygen evolution overpotential of this electrode is at 10 mA / cm2 and 250 mA / cm 2 At the current densities of, the oxygen evolution overpotentials are 97 mV and 296 mV, respectively.

[0130] Therefore, by increasing the magnetic field strength and optimizing the electrodeposition conditions, the electrodes of Examples 1-5 prepared an alkaline water electrolysis hydrogen production electrode with higher catalytic activity. A cone structure and a surface structure with specific structures and chemical compositions were grown on the surface of the conductive substrate; when the alkaline water electrolysis hydrogen production electrode was working, an oxygen evolution reaction and a hydrogen evolution reaction could occur. When the alkaline water electrolysis hydrogen production electrode was used as the anode, the alloy oxide layer and the metal single layer could maintain their original states. When the alkaline water electrolysis hydrogen production electrode was used as the cathode, the multi-stage cone structure significantly reduced the energy barrier of the hydrogen evolution reaction by increasing the local electric field strength, and the cone structure itself had good mechanical stability. Therefore, it had both chemical stability and mechanical stability at the same time, and the electrode could work for a long time at a high current density. It was an efficient, stable and industrialized alkaline water electrolysis hydrogen production electrode solution.

[0131] The above are only specific embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent transformation using the present invention, directly or indirectly applied in other related technical fields, shall be included in the patent protection scope of the present invention by the same token.

Claims

1. An alkaline electrolyzed water hydrogen production electrode, comprising a conductive substrate, characterized in that: A nickel-containing or nickel alloy conical array structure is formed on the surface of the conductive substrate by magnetic field-assisted electrodeposition; The conical array structure includes a primary conical array at the bottom layer and a secondary conical array grown on its surface.

2. The alkaline electrolyzed water hydrogen production electrode according to claim 1, characterized in that: The aspect ratio of the primary conical array is 2-4:1, and the aspect ratio of the secondary conical array is 4-6:

1.

3. The hydrogen production electrode for alkaline electrolyzed water according to claim 1, characterized in that, The electroplating solution for forming a conical array structure containing nickel or nickel alloy, in each liter of the electroplating solution, contains the following raw materials: 0.1-1 mol of metal ions; nickel salt; H3BO3; NH4Cl; The molar ratio of metal ions, nickel salt, H3BO3, and NH4Cl is 1:0.2-1.2:0.2-1.2:0.5-5.

0.

4. The alkaline electrolyzed water hydrogen production electrode according to claim 3, characterized in that, The metal ions are from one or more of iron salts, cobalt salts, molybdates, tungstates, gold salts, and copper salts.

5. The hydrogen production electrode for alkaline electrolyzed water according to claim 4, characterized in that, The nickel salt is one or more of nickel chloride, nickel nitrate, nickel acetate, nickel sulfate, nickel oxalate, nickel perchlorate, nickel chlorate, nickel bromide; the iron salt is one or more of ferric chloride, ferrous chloride, ferrous nitrate, ferric sulfate, ferrous sulfate, ferric oxalate, ferrous oxalate, ferric acetate, ferric perchlorate, ferrous chlorate, ferrous acetate, ferric bromide; the cobalt salt is one or more of cobalt chloride, cobalt nitrate, cobalt sulfate, cobalt oxalate, cobalt chlorate, cobalt perchlorate, cobalt acetate; the molybdate is one or more of sodium molybdate, ammonium molybdate, molybdic acid, molybdenyl chloride; the tungstate is one or more of ammonium tungstate, sodium tungstate, potassium tungstate, lithium tungstate; the gold salt is one or more of chloroauric acid, potassium aurocyanide, bromoauric acid, gold thiosulfate; the copper salt is one or more of copper sulfate, copper chloride, copper nitrate, copper cyanide, copper acetate.

6. The hydrogen production electrode for alkaline electrolyzed water according to claim 4, characterized in that, The nickel alloy with a tapered array structure, the chemical composition of the nickel alloy is selected from any one of the following chemical formulas Ni 100-x Z x , Z is a metal element, and x is between 1 and 5; Ni 100-x Fe x , where x is between 5 and 25; Ni 100-x Co x , where x is between 5 and 25; Ni 100-x Mo x , where x is between 5 and 25; Ni 100-x W x , where x is between 5 and 25; Ni 100-x Au x , where x is between 5 and 25; Ni 100-x Cu x , where x is between 5 and 25.

7. A method for preparing an alkaline electrolyzed water hydrogen production electrode, which is used to prepare the alkaline electrolyzed water hydrogen production electrode according to any one of claims 1-6, characterized in that, It includes the following steps: S1. Electroplating solution preparation: The nickel salt, metal ions, H3BO3, NH4Cl and water are fully mixed, and the pH is adjusted to 3.5-4.5 to obtain the electroplating solution; S2. Magnetic field-assisted electrodeposition: Using an inert conductor as the anode and a conductive substrate as the cathode; applying a magnetic field perpendicular to the surface of the substrate to uniformly cover the entire electrolysis area; performing electrodeposition using a DC power source or a pulsed power source, where the magnetic field intensity B(t) is dynamically adjusted according to the formula B(t) = B0 + (B f - B0)(t / T) α where t is the time during the deposition process, T is the total deposition time, B0 is the initial magnetic field intensity, and B f is the final magnetic field intensity, and α is the regulation index; S3. Post-treatment: After the electrodeposition is completed, the conductive substrate is taken out, washed and dried to obtain an electrode with a nickel alloy multi-stage conical structure.

8. The alkaline electrolyzed water hydrogen production electrode according to claim 7, characterized in that In step S2, during the deposition process, it successively experiences three stages: the early stage, the middle stage, and the late stage. In the early stage, a magnetic field intensity of 100 - 1000 Gs and a current density of 20 - 30 mA / cm 2 are used. In the middle stage, a magnetic field intensity of 1000 - 5000 Gs and a current density of 30 - 50 mA / cm 2 are used. In the late stage, the magnetic field intensity of the middle stage is maintained and the current density is adjusted to 20 - 30 mA / cm 2 to form a multi-stage tapered structure.

9. Application of an alkaline electrolyzed water hydrogen production electrode, characterized in that, The alkaline electrolyzed water hydrogen production electrode is applied to the field of electrolyzed water, and the alkaline electrolyzed water hydrogen production electrode is the alkaline electrolyzed water hydrogen production electrode described in any one of claims 1-6 or the alkaline electrolyzed water hydrogen production electrode prepared by the preparation method described in any one of claims 7-8.

10. A catalyst system for preparing an alkaline electrolyzed water hydrogen production electrode, which is used to prepare the alkaline electrolyzed water hydrogen production electrode according to any one of claims 1-6 or the alkaline electrolyzed water hydrogen production electrode prepared by the preparation method according to any one of claims 7-8, characterized in that, It includes: Vertically installed electromagnetic coils or permanent magnet arrays for providing a vertical magnetic field of 100-5000 Gs; An electrodeposition tank for loading the electroplating solution and completing the electrodeposition of the conductive substrate; A temperature control unit for controlling the temperature of the electroplating solution within the range of 30-80 °C; Power supply module, used to provide a DC current of 20 - 50 mA / cm 2 ​

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