A sabina branch-like nickel dendrite water electrolysis hydrogen electrode, a preparation method and application thereof

Abstract

The application discloses a Sabina procumbens branch-like nickel dendrite water electrolysis hydrogen electrode and a preparation method and application thereof, and belongs to the technical field of water electrolysis hydrogen electrodes.The Sabina procumbens branch-like nickel dendrite water electrolysis hydrogen electrode is prepared by electrodeposition in a nickel-containing electroplating solution under the conditions of a magnetic field and alternating ultrasonic waves, with a metal base as a cathode; the metal base is in the magnetic field, and the direction of the magnetic field is parallel to the surface of the metal base.The Sabina procumbens branch-like nickel dendrite water electrolysis hydrogen electrode is prepared by the method based on the magnetic field and the alternating ultrasonic waves, and the process is simple and one-step electrodeposition is achieved; the prepared Sabina procumbens branch-like nickel dendrite water electrolysis hydrogen electrode has a Sabina procumbens branch-like nickel dendrite structure, has good catalytic activity and stability, and is suitable for industrial-grade large-current-density water electrolysis hydrogen production.

Description

Technical Field

[0001] This invention belongs to the field of electrolytic water hydrogen production electrode technology, specifically relating to a juniper dendritic nickel dendrite electrolytic water hydrogen production electrode, its preparation method, and its application. Background Technology

[0002] Against the backdrop of a global push for clean energy transition, alkaline water electrolysis technology holds a significant position in hydrogen production due to its relatively stable performance. However, currently, precious metal catalysts such as Pt are mainly used in industry as the matrix for the hydrogen evolution reaction (HER) catalyst in water electrolysis for hydrogen production. This significantly increases the cost of water electrolysis and severely restricts the further promotion and application of alkaline water electrolysis technology in large-scale, low-cost hydrogen production (Chem. Rev. 2024, 124, 9, 5617–5667). Furthermore, the electrocatalytic reaction for water electrolysis still faces numerous challenges in industrial applications. On the one hand, most catalyst materials remain in the laboratory stage. The production of these materials often faces problems such as complex processes, poor stability, the need for special reaction conditions, and difficulty in achieving large-area preparation, which are detrimental to large-scale industrial production (InfoMat. 2022;4:e12357). For example, hydrothermal methods require strict reaction conditions and expensive reaction equipment; activated carbon-supported methods and vapor deposition methods involve complex production steps; and multi-step electrodeposition requires more complex design steps in industrial applications, increasing costs. Furthermore, poor electrode mass transfer is a significant challenge. Low mass transfer efficiency between reactants and products on the electrode surface limits the reaction rate, making stable operation at industrial-grade current densities difficult (Adv. Sci. 2025, 2412962). Simultaneously, poor electrode mass transfer leads to poor intrinsic catalytic activity of the catalyst material, requiring it to operate at higher potentials. This necessitates additional energy consumption to drive the reaction and limits the electrode's sustained stable operation, further exacerbating the higher costs and energy consumption associated with industrial water electrolysis for hydrogen production (Adv. Energy Mater. 2020, 10, 2002955). Moreover, the overall performance of water electrolysis is inextricably linked to the efficiency of bubble separation on the electrode surface. The size of the electrolyzer, the shape of the flow field, the pore size, and the ability to adhere gases to the electrode surface are closely related. Therefore, technological advancements in this field place new demands on electrodes with controllable and tunable surface microstructures to adapt to changes in the electrolyzer structure across production scenarios.

[0003] Therefore, developing non-precious metal catalysts suitable for industrial production, characterized by high activity, high utilization rate, and controllable surface microstructure, while improving their adaptability and mass transfer efficiency at industrial-grade current densities, is a pressing industrial challenge and a new direction for development. Answering these questions is crucial for promoting the upgrading of alkaline water electrolysis technology, reducing the cost of green hydrogen production, and realizing a sustainable energy development strategy. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a juniper-shaped nickel dendrite electrolysis water-to-hydrogen electrode, its preparation method, and its application. This juniper-shaped nickel dendrite electrolysis water-to-hydrogen electrode is an electrolysis water-to-hydrogen electrode with nickel dendrites exhibiting a juniper-shaped morphology. Addressing the high cost issues associated with precious metal catalysts in existing technologies, as well as the challenges of high material preparation costs, complex production processes, poor electrode mass transfer, high overpotential under high current, and the inability to achieve continuously tunable surface microstructures in electrocatalytic reactions, these problems severely hinder the efficient development and widespread application of water electrolysis technology. This invention, through a "one-step deposition-fractal framework-particle synergy" strategy, demonstrates its outstanding advantages in simultaneously achieving simplified processes, large-area production, high activity, high stability, and rapid mass transfer in water electrolysis.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] This invention provides a method for preparing a juniper dendritic nickel dendrite electrolysis water-to-hydrogen electrode, comprising the following steps:

[0007] Under magnetic field and alternating ultrasonic conditions, a nickel dendrite electrolysis hydrogen production electrode with juniper-like crystals is obtained by electrodeposition in a nickel-containing electroplating solution using a metal substrate as the cathode. The metal substrate is placed in a magnetic field, the direction of which is parallel to the surface of the metal substrate (i.e., the direction of the magnetic field is perpendicular to the direction of the electric field). This method, employing an external magnetic field combined with alternating ultrasonic assistance, allows for large-area loading of nickel dendrites on the substrate and enhances surface adhesion. The alternating ultrasonic assistance suppresses uncontrolled lateral branch growth, resulting in a unique granular, stacked juniper-like morphology.

[0008] Preferably, the magnetic field is generated by N-pole and S-pole magnets positioned on both sides of the metal substrate and parallel to the thickness surface of the metal substrate.

[0009] More preferably, the surface magnetic field strength of the magnet is 8000-10000 Gs, and the distance between the two magnets is 2-30cm.

[0010] More preferably, the surface magnetic field strength of the magnet is 9000 Gs.

[0011] More preferably, the long side dimension of the magnet should be consistent with the height of the electrolytic cell (10-20 cm), the width should be 3-5 cm, and the thickness should be 2-5 cm.

[0012] Preferably, the parameters of the alternating ultrasound are: alternating ultrasound with a time of 25-35 s and a frequency of 15-25 kHz and ultrasound with a time of 25-35 s and a frequency of 35-45 kHz.

[0013] More preferably, the parameters of the alternating ultrasound are: ultrasound with a time of 30 s and a frequency of 20 kHz and ultrasound with a time of 30 s and a frequency of 40 kHz are alternated.

[0014] Preferably, the metal substrate is a metal sheet, foil, mesh, or porous metal substrate.

[0015] More preferably, the metal sheet, foil, or mesh is Ni foil, Ni mesh, Ti foil, Ti mesh, stainless steel sheet, or stainless steel mesh.

[0016] More preferably, the porous metal substrate is nickel foam, iron foam, copper foam, or nickel felt.

[0017] Preferably, the metal substrate undergoes pretreatment before electrodeposition.

[0018] More preferably, when the metal substrate is a metal sheet, foil, or mesh, the pretreatment is sanding, cleaning, and drying; when the metal substrate is a porous metal substrate, the pretreatment is pickling, cleaning, and drying.

[0019] Preferably, the concentration of nickel ions in the nickel-containing electroplating solution is 0.1-1 mol / L.

[0020] Preferably, the pH of the nickel-containing electroplating solution is 1-5.5.

[0021] Preferably, the temperature of the nickel-containing electroplating solution is 40-70°C.

[0022] Preferably, the electrodeposition current is 50-180 mA / cm. 2 The direct current is applied for 3-20 minutes.

[0023] Preferably, the nickel-containing electroplating solution contains a nickel salt, which is one or more of nickel sulfate, nickel chloride, nickel nitrate, nickel acetate, nickel oxalate, nickel perchlorate, nickel chlorate, and nickel bromide.

[0024] Preferably, the nickel-containing electroplating solution also includes a pH buffer.

[0025] More preferably, the molar ratio of nickel ions to pH buffer in the nickel-containing electroplating solution is 1:1 to 1:1.5.

[0026] More preferably, the pH buffer is an ammonium salt.

[0027] More preferably, the ammonium salt is one or more of ammonium sulfate, ammonium bisulfate, ammonium chloride, and ammonium nitrate.

[0028] Preferably, the distance between the working anode and the working cathode of the electrodeposition is 2-10 cm.

[0029] More preferably, the working anode is an inert conductor.

[0030] More preferably, the inert conductor is a carbon rod.

[0031] This invention provides a juniper-shaped nickel dendrite electrolysis hydrogen production electrode prepared by the above-described method. The electrode comprises a conductive metal substrate, on the surface of which a catalyst with a juniper-shaped nickel dendrite structure of granular, stacked growth is deposited in a tightly adhered and orderly manner; the nickel dendrite structure radiates outward from the conductive metal substrate in a Y-shape. Furthermore, the morphology of the dendrites can be continuously and controllably adjusted by regulating the magnetic field, temperature field, alternating ultrasound, electrodeposition time, and current density.

[0032] This invention provides an application of the above-mentioned juniper dendritic nickel dendrite electrolysis water production hydrogen electrode in water electrolysis hydrogen production.

[0033] Preferably, the juniper dendritic nickel dendrite electrolysis hydrogen production electrode serves as the cathode in the water electrolysis hydrogen production process.

[0034] Preferably, the current density for hydrogen production via water electrolysis is 10-1000 mA / cm². 2 .

[0035] Preferably, the electrolyte for producing hydrogen by electrolysis of water is an alkaline electrolyte.

[0036] More preferably, the alkaline electrolyte is a 1-8 mol / L KOH solution.

[0037] The preparation method of the present invention simplifies the process:

[0038] Traditional methods for preparing electrodes for hydrogen production via water electrolysis often involve complex, multi-step processes, requiring expensive equipment and chemical reagents. These processes are cumbersome and demanding in terms of environmental requirements. This invention employs a one-step electrodeposition method, significantly simplifying the preparation process. After preparing an electroplating solution containing a nickel mixture, by simply adding an inexpensive permanent magnet and an alternating ultrasonic device, and by constructing a two-electrode system and setting appropriate electrodeposition parameters, a catalytic electrode structure loaded with juniper-like nickel dendrites can be directly obtained on a simply pretreated metal substrate. This technology eliminates the need for complex intermediate product synthesis and complex electroplating solution preparation, significantly reducing material waste and equipment costs during the preparation process, and effectively promoting the upgrading of alkaline water electrolysis hydrogen production electrode preparation technology.

[0039] The juniper dendritic nickel dendrite electrolytic hydrogen production electrode prepared by this invention has a Y-shaped outward radial growth of its juniper dendritic particle stacked structure, which optimizes intrinsic catalytic performance, promotes mass transfer, and provides the electrode with conditions suitable for high-current operation.

[0040] At industrial-grade current densities, many traditional electrodes suffer from poor mass transfer, leading to decreased electrode stability and failing to meet the demands for efficient hydrogen production. The alkaline water electrolysis hydrogen production electrode of this invention, with its unique juniper-like nickel dendrite structure, possesses excellent high-current stable operation capabilities. Under high current density conditions, this structure maintains efficient charge transport and mass exchange. On one hand, the nickel dendrites increase the specific surface area of ​​the catalytic electrode, providing more abundant electrochemical active sites, thus enabling the hydrogen evolution reaction to proceed continuously and rapidly under high current. On the other hand, the electrode's unique juniper-like particle stacked structure, with its tips, edges, and branch connections rich in lattice defects (dislocations, vacancies, etc.) and high-index nickel crystal planes ((210) planes, etc.), provides superior adsorption energy for water splitting intermediates (*H), lowering the reaction energy barrier. Therefore, this electrode exhibits excellent intrinsic HER catalytic activity. Furthermore, the unique juniper-like dendrites of this electrode, with their overlapping and Y-shaped branching structure, reduce the gas-liquid-solid three-phase contact angle, accelerating bubble detachment. The juniper-like electrode also sways and ejects bubbles during electrolysis, thus forming a catalyst structure with enhanced mass transfer, especially at high current densities. In addition, the continuous branches of the dendrite structure form a three-dimensional conductive network, reducing the overall electrode resistance, and the gaps between the Y-shaped dendrite branches create hierarchical channels, accelerating the transport of water molecules and ions in the electrolyte and alleviating the concentration polarization problem that is difficult to eliminate with traditional electrodes at industrial-grade current densities. These two structural advantages suppress the catalytic activity decay of the electrode at high current densities, thereby achieving highly efficient water electrolysis for hydrogen production.

[0041] The juniper dendritic nickel dendrite electrolytic hydrogen production electrode prepared by this invention has a continuously tunable surface microstructure:

[0042] As the applications of water electrolysis continue to expand, new demands are being placed on the ability of electrodes to possess controllable and tunable surface microstructures to adapt to changes in the electrolyzer structure as production scenarios change. Currently, the scientific community has developed catalysts with excellent intrinsic catalytic activity; however, their surface morphology is often singular and cannot be continuously controlled. This work employs a magnetic field + alternating ultrasonic-assisted electrodeposition technique. The coupling of these two techniques broadens the degree of freedom in controlling the structure of nickel dendrites, achieving continuous tunability of the electrode microstructure, and is expected to pave the way for the diversified development of future electrolyzer structures.

[0043] The juniper dendritic nickel dendrite electrolytic hydrogen production electrode prepared by this invention has the advantages of large-area production and the ability to operate stably under industrial-grade current density:

[0044] From an industrial production perspective, the significant changes in temperature and concentration during traditional electrodeposition make it extremely difficult to achieve large-area catalyst production and stability at industrial-grade current densities. This innovative technology overcomes this limitation by employing magnetic field-assisted alternating ultrasonic electrodeposition, achieving large-area production of electrodeposited dendrites and stability at industrial-grade current densities. From a structural stability perspective, on the one hand, the one-step electrodeposition process optimized by magnetic field assistance and alternating ultrasound ensures a strong bond between the dendrites and the substrate, avoiding the instability of traditional electrodeposited dendrites. Juniper-like nickel dendrites grow tightly on the metal substrate, and during long-term water electrolysis, the juniper-like nickel dendrite structure is not easily detached or deformed. On the other hand, the alternating ultrasonic program generates 0.8 ms of [something unclear - possibly related to a specific process or process] on the electrode surface. -1 The microjets effectively "shaving off" weak points in the side branches, while the reinjection of fresh electrolyte not only improves process stability but also promotes orderly dendrite growth. Reduced side branches lead to faster bubble desorption under high current, less stress concentration, and thus easier stability maintenance. The designed magnetic field and alternating ultrasonic coupling-assisted electrodeposition process contribute to its high stability. Furthermore, in terms of chemical stability, the electrode effectively resists corrosion in alkaline electrolytes, maintaining catalytic activity. Even under prolonged, high-load operating conditions, its catalytic performance remains at a high level, ensuring the continuity and reliability of the water electrolysis hydrogen production process. In industrial hydrogen production scenarios, the electrode of this invention can operate stably, reducing equipment maintenance and replacement frequency, lowering overall operating costs, and demonstrating promising practical applications.

[0045] The beneficial effects of this invention are:

[0046] This invention relates to a method for preparing a juniper dendritic nickel dendrite electrolytic water-to-hydrogen electrode based on magnetic field and alternating ultrasound. The process is simple and involves a one-step electrodeposition. The prepared juniper dendritic nickel dendrite electrolytic water-to-hydrogen electrode has a juniper dendritic nickel dendrite structure, exhibits good catalytic activity and stability, and is suitable for industrial-grade high-current-density water electrolysis for hydrogen production. Attached Figure Description

[0047] Figure 1 This is a scanning electron microscope (SEM) image of the dendritic nickel dendritic electrode prepared in Example 1 of the present invention.

[0048] Figure 2 A photo of a Chinese juniper in Xinjiang;

[0049] Figure 3 The HER polarization curve (95% IR compensation) of the juniper dendritic nickel dendrite electrode prepared in Example 1 of the present invention in 1 M KOH.

[0050] Figure 4 The CV curves of the juniper dendritic nickel dendrite electrode prepared in Example 1 of the present invention at different scan rates in 1 M KOH;

[0051] Figure 5 C is the juniper dendritic nickel dendritic electrode prepared in Example 1 of this invention. dl Computational graph;

[0052] Figure 6 The potential-time curve of the juniper dendritic nickel dendrite electrode prepared in Example 1 of the present invention after 100 h of stability testing in 1 M KOH;

[0053] Figure 7 This is a scanning electron microscope (SEM) image of the juniper dendritic nickel dendrite electrode prepared in Example 2 of the present invention.

[0054] Figure 8 The HER polarization curve (95% IR compensation) of the juniper dendritic nickel dendritic electrode prepared in Example 2 of the present invention in 1 M KOH.

[0055] Figure 9 This is a SEM image of the juniper dendritic nickel dendrite electrode prepared in Example 3 of the present invention;

[0056] Figure 10 The HER polarization curve (95% IR compensation) of the juniper dendritic nickel dendrite electrode prepared in Example 3 of the present invention in 1 M KOH.

[0057] Figure 11 SEM image of the juniper dendritic nickel dendrite electrode prepared in Comparative Example 1 of this invention;

[0058] Figure 12This is a SEM image of the electrode prepared in Comparative Example 2 of this invention;

[0059] Figure 13 SEM image of the electrode prepared in Comparative Example 3 of this invention;

[0060] Figure 14 This is a SEM image of the electrode prepared in Comparative Example 4 of the present invention;

[0061] Figure 15 Comparison of HER polarization curves (95% IR compensation) of electrodes prepared in Examples 1-3 and Comparative Examples 1-5 of this invention in 1 M KOH. Detailed Implementation

[0062] The present invention will be further described below with reference to embodiments.

[0063] The following will clearly and completely describe the concept, specific solutions, and technical effects of the present invention with reference to embodiments, so as to fully understand the purpose, features, and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. The various technical features in the present invention can be combined interactively without contradicting each other.

[0064] To overcome the problems of high cost and low catalytic activity of existing alkaline water electrolysis hydrogen production electrodes, this invention provides a high-performance juniper dendritic nickel dendrite water electrolysis hydrogen production electrode, its preparation method, and its application. This electrode is prepared by a simple, mild, and single-material one-step electrodeposition process. The preparation method of the aforementioned juniper dendritic nickel dendrite water electrolysis hydrogen production electrode includes the following steps: substrate pretreatment, electroplating solution preparation, pH and temperature adjustment, placement of a permanent magnet and setting of alternating ultrasonic parameters, and one-step electrodeposition.

[0065] Specifically, this invention provides a method for preparing a juniper-shaped nickel dendrite electrolysis water-to-hydrogen electrode, comprising the following steps:

[0066] S1. Substrate pretreatment.

[0067] First, the selected metal substrate undergoes pretreatment. If the metal substrate is a Ni foil, Ni mesh, Ti foil, Ti mesh, stainless steel sheet, stainless steel mesh, or other metal sheet or mesh material, it needs to be sanded sequentially to remove the surface oxide layer, oil, and other impurities. After sanding, it is ultrasonically cleaned in an organic solvent such as ethanol or acetone for 15-30 minutes. After cleaning, it is rinsed thoroughly with deionized water and dried in a vacuum oven at 60-80°C for approximately 1-2 hours. For substrates with porous structures such as foamed nickel, foamed iron, foamed copper, and nickel felt, activation treatment is required. It is immersed in a 1 M-5 M hydrochloric acid solution for 10-20 minutes to remove the surface passivation layer, then rinsed with deionized water until neutral and dried.

[0068] S2. Prepare nickel-containing electroplating solution.

[0069] Accurately weigh the nickel salt according to the standard of 0.1-1 mol of nickel metal ions per liter of electroplating solution. The nickel salt can be selected from one or more of nickel sulfate, nickel chloride, nickel nitrate, nickel acetate, nickel oxalate, nickel perchlorate, nickel chlorate, and nickel bromide, and mixed together. Accurately weigh ammonium chloride according to a nickel metal ion to ammonium salt molar ratio of 1:1 to 1:1.5, add it to the above nickel salt solution, and stir continuously for 10-20 minutes until completely dissolved.

[0070] S3. Use a pH adjuster to adjust the pH value and temperature of the electroplating solution.

[0071] Ammonia and HCl were selected as pH adjusters. The prepared electroplating solution was placed on a magnetic stirrer, and ammonia or HCl solution was slowly added dropwise while the pH value of the electroplating solution was monitored in real time using a pH meter. The pH value was adjusted to pH=1-1.5, pH=3-3.5, pH=4-4.5, and pH=5-5.5. Furthermore, the temperature during the electroplating process needed to be precisely controlled within the range of 40-70℃, and uniform heating of the electroplating solution was ensured.

[0072] S4. Electrodeposition is assisted by a combination of magnetic field and alternating ultrasonic waves.

[0073] During electrodeposition, two magnets are placed 2 cm apart on either side of the metal substrate, parallel to the thickness of the substrate, ensuring that the N and S poles of the magnets are aligned. At the start of electrodeposition, the apparatus is placed in an ultrasonic machine, and the ultrasonic program is set to an alternating program of 30 s at 20 kHz and 30 s at 40 kHz until the electrodeposition process is complete. The long side of the magnets should be consistent with the height of the electrolytic cell (10-20 cm), the width 3-5 cm, and the thickness 2-5 cm. The distance between the two magnets should be 2-30 cm, and the surface magnetic field strength of the magnets should be in the range of 8000-10000 Gs.

[0074] S5. Preparation of a catalytic electrode for hydrogen production by electrolysis of water supported on a metal substrate by one-step electrochemical deposition of nickel dendrites in the form of juniper branches.

[0075] Using an inert conductor as the working anode, the pretreated metal substrate obtained in step S1 is used as the working cathode and inserted into an electroplating solution with adjusted pH and temperature for electrodeposition. After electrodeposition, the metal substrate is removed to obtain a catalytic electrode for hydrogen production by water electrolysis with juniper dendrites loaded on the metal substrate.

[0076] In step S5, the distance between the working anode and the working cathode is 2-10 cm, and the current density is 50-80 mA / cm². 2 100-125 mA / cm 2 150-180 mA / cm 2 Electrochemical deposition is performed using direct current, with a deposition time of 3-20 minutes.

[0077] The water electrolysis hydrogen production electrode prepared by the above preparation method includes a conductive metal substrate, on which a catalyst with a juniper dendritic nickel dendrite structure is deposited.

[0078] The aforementioned water electrolysis hydrogen production electrode is applied to the field of water electrolysis. Specifically, the juniper branch-shaped water electrolysis hydrogen production electrode is used in an alkaline electrolyte environment (such as 1-8 mol / L KOH solution) to achieve a highly efficient and stable alkaline water electrolysis hydrogen production reaction through electrocatalysis. Applications include alkaline water electrolysis hydrogen production and hydrogen production units in distributed energy systems.

[0079] Example 1

[0080] A method for preparing a juniper dendritic nickel dendrite electrolysis water-to-hydrogen electrode includes the following steps:

[0081] (1) Treatment of conductive substrate

[0082] Select a 1 mm thick nickel foam, sonicate it in a 1 M HCl solution for 8 minutes to remove the oxide layer on the surface, then rinse it with ethanol and deionized water in sequence, and then dry it in a 60 ℃ oven for later use.

[0083] (2) Preparation of electroplating solution containing nickel mixture

[0084] 0.6 M nickel chloride (NiCl2) was used as the nickel salt to provide metal ions. The nickel salt was dissolved in an appropriate amount of deionized water, and the solution was stirred at 400 rpm for 15 minutes using a magnetic stirrer until completely dissolved. Then, ammonium chloride was added at a NiCl2 to ammonium chloride molar ratio of 1:1.2, and stirring continued for 40 minutes to obtain an electroplating solution containing a nickel mixture. The pH of the electroplating solution was adjusted to 4.0 using ammonia and HCl, and the electrolyte temperature was adjusted to 40°C.

[0085] (3) Place a permanent magnet and set an alternating ultrasonic program.

[0086] During electrodeposition, two symmetrical magnets with a surface magnetic field strength of 10000 Gs are placed close to the electrolytic cell in a direction parallel to the thickness surface of the cathode substrate, ensuring that the N and S poles of the magnets are opposite each other. The long side of the magnets should be consistent with the height of the electrolytic cell (10 cm), with a width of 4 cm and a thickness of 3 cm, and the distance between the two magnets should be 5 cm. At the start of electrodeposition, the apparatus is placed in an ultrasonic machine, and the ultrasonic program is set to an alternating ultrasonic program with a duration of 30 s at a frequency of 20 kHz and a duration of 30 s at a frequency of 40 kHz, until the electrodeposition program is completed.

[0087] (4) One-step electrodeposition to prepare catalytic electrodes.

[0088] Using a carbon rod as the working anode and the conductive substrate prepared in step (1) as the working cathode, the electrodeposition system was immersed in the electroplating solution prepared in step (2), with a distance of 5 cm between the working anode and the working cathode. Subsequently, an electrodeposition system was constructed, and a current density of 125 mA / cm² was applied. 2 Electrochemical deposition was performed using direct current for 15 minutes.

[0089] (5) After deposition, the conductive substrate is removed, rinsed with deionized water 5 times, and then dried in an oven at 60 ℃ for 1.5 hours to obtain an electrolytic hydrogen production electrode with juniper dendrites loaded on the surface.

[0090] Depend on Figure 1 and Figure 2It can be clearly determined that the granular, stacked nickel dendrite structure exhibits a highly ordered juniper-like shape. This unique structure not only optimizes the intrinsic catalytic activity but also significantly increases the electrode's specific surface area, providing abundant active sites for the hydrogen evolution reaction. Simultaneously, when this electrode is used as a cathode for the hydrogen evolution reaction, the nickel dendrite structure effectively promotes ion transport and bubble removal in the electrolyte, enhancing mass transfer and accelerating the reaction. Furthermore, the electrode surface morphology of this embodiment is characterized by densely growing granular, stacked nickel dendrites, dendrite trunk lengths of 10-20 μm, dendrite trunk diameters of 1-2 μm, dendrite spacing of 1-1.5 μm, and Y-shaped intersections of the dendrites at angles ranging from 40-90° to the trunk.

[0091] The obtained juniper dendritic nickel dendrite electrolysis hydrogen production electrode was subjected to the following electrochemical tests:

[0092] Electrochemical tests were performed on the electrodes at room temperature using a CHI 660E electrochemical workstation. The electrolytic cell was a standard three-electrode system. The alkaline water electrolysis hydrogen production electrode obtained in this embodiment was clamped with a platinum electrode as the working electrode, a graphite rod as the counter electrode, and Hg / HgO as the reference electrode. The electroplating solution was 1 mol / L KOH. The linear sweep voltammogram (LSV) scan rate was 2 mV / s, the voltage was manually compensated using 95% iR, and the potential scan range was (-0.6) - (-1.4) V. Based on the formula: Overpotential = Actual Measured Potential + 0.059 × pH + 0.095 V, the overpotential of the juniper dendritic nickel dendritic water electrolysis hydrogen production electrode in this embodiment at 10 mA / cm² was calculated. 2 500 mA / cm 2 and 800 mA / cm 2 The hydrogen evolution overpotentials at the specified current densities were 59 mV, 293 mV, and 322 mV, respectively. Furthermore, comparison with the control sample revealed that the catalytic performance of the electrode prepared in this embodiment significantly exceeded that of the unsupported nickel foam electrode (10 mA / cm²). 2 500 mA / cm 2 The hydrogen evolution overpotentials at current densities were 226 mV and 500 mV, respectively. Furthermore, the material double-layer capacitance (C0) was measured using CV with different sweep numbers. dl To determine the electrochemically active area (ECSA) of the juniper dendritic nickel dendrite electrolytic water electrolysis hydrogen production electrode prepared in this embodiment, such as... Figure 4 and Figure 5 As shown, the results indicate that the electrode has a large active area to provide the large number of active sites required at industrial-grade current densities.

[0093] Figure 6The stability curve of the juniper dendritic nickel dendrite electrolytic hydrogen production electrode prepared in this embodiment in an alkaline environment of 1 M KOH is shown. This catalyst exhibits stability in real alkaline seawater at 500 mA / cm². 2 The current density remained stable for 100 hours without significant activity decay, indicating the potential for longer-term stable operation. This strongly demonstrates that the juniper dendritic nickel dendrite water electrolysis hydrogen production electrode can operate stably for extended periods in a real alkaline environment at industrial-grade electrolysis current densities.

[0094] Example 2

[0095] A method for preparing a juniper dendritic nickel dendrite electrolysis water-to-hydrogen electrode includes the following steps:

[0096] The difference from Example 1 is as follows: in step (2), 0.6 M nickel chloride (NiCl2) is used as the nickel salt, and the molar ratio of metal ions to ammonium chloride is adjusted to 1:1.3; the pH of the electroplating solution is adjusted to 5.0, and the electrolyte temperature is adjusted to 50 °C; the surface magnetic field strength of the permanent magnet in step (3) is 9000 Gs; and the current density in step (4) is 150 mA / cm. 2 The electrodeposition time was 10 min. The remaining steps were the same as in Example 1.

[0097] Depend on Figure 7 It can be seen that the juniper-like nickel dendrites in this embodiment are similar to those in Example 1, but exhibit a more slender dendritic structure. Furthermore, this water electrolysis hydrogen production electrode operates at 10 mA / cm². 2 500 mA / cm 2 and 800 mA / cm 2 The hydrogen evolution overpotentials at the current densities were 92 mV, 315 mV, and 345 mV, respectively. Figure 8 Furthermore, the electrode surface morphology of this embodiment is similar to that of Example 1, featuring granular stacked nickel dendrites, but exhibiting a more slender and sparser dendritic structure. The dendrite length is 5-18 μm, the dendrite trunk diameter is 0.5-0.8 μm, the dendrite spacing is 2-4 μm, and the Y-shaped intersections of the dendrites have an angle range of 30-50° with the trunk. Although the catalytic performance of this electrode is not as good as that of Example 1, it still exhibits good performance in water electrolysis for hydrogen production, and its performance is still far superior to the foamed nickel electrode without juniper dendrites (10 mA / cm²). 2 500 mA / cm 2 The hydrogen evolution overpotentials at the current densities are 226 mV and 500 mV, respectively.

[0098] Example 3

[0099] A method for preparing a juniper dendritic nickel dendrite electrolysis water-to-hydrogen electrode includes the following steps:

[0100] The difference from Example 1 is that in step (2), 0.5 M nickel chloride (NiCl2) is used as the nickel salt, ammonium chloride is used as the pH buffer, the molar ratio of metal ions to ammonium chloride is 1:1.2, the pH of the electroplating solution is adjusted to 5.0, and the temperature is set to 50°C. In step (4), the current density is 80 mA / cm². 2 The electrodeposition time was 20 min, and the remaining steps were the same as in Example 1.

[0101] The alkaline water electrolysis hydrogen production electrode prepared in this embodiment exhibits a different growth morphology in its nickel dendrite structure compared to Examples 1 and 2. Figure 9 It can be seen that the dendrites are relatively thinner and longer, and the dendrite branches are fuller and more evenly distributed. From Figure 10 It can be obtained that the electrode is at 10 mA / cm 2 500 mA / cm 2 and 800 mA / cm 2 The hydrogen evolution overpotentials at the specified current densities were 94 mV, 336 mV, and 353 mV, respectively. Although the catalytic performance of this electrode was not as good as that of Example 1, it still exhibited good performance in hydrogen production through water electrolysis, and was still far superior to the unsupported nickel foam electrode (10 mA / cm²). 2 500 mA / cm 2 The hydrogen evolution overpotentials at the given current densities are 226 mV and 500 mV, respectively. Furthermore, the electrode surface morphology in this embodiment is characterized by densely growing granular, multi-layered nickel dendrites, exhibiting a dendritic structure with more side branches that are shorter and sparser. The dendrite length is 8-15 μm, the dendrite trunk diameter is 0.5-0.8 μm, the dendrite spacing is 2-3 μm, and the Y-shaped intersections of the dendrites have an angle range of 40-60° with the trunk.

[0102] Therefore, in the embodiments, by adjusting parameters such as electrodeposition time, electrodeposition temperature, electrodeposition pH, and the concentration of nickel-containing substances, electrolytic water-generating electrodes with different juniper-like nickel dendrite morphologies were successfully prepared. During water electrolysis, when these electrodes act as cathodes and undergo the hydrogen evolution reaction, the juniper-like dendritic particle stacked nickel dendrite structure effectively promotes the reaction, reduces the hydrogen evolution overpotential, and thus yields highly efficient alkaline electrolytic water-generating electrodes capable of long-term stable operation.

[0103] Comparative Example 1

[0104] A method for preparing a juniper dendritic nickel dendrite electrolysis water-to-hydrogen electrode includes the following steps:

[0105] The difference from Example 1 is that the added ultrasound is a constant frequency of 40 kHz ultrasound, while the rest of the steps are the same as in Example 1.

[0106] Figure 11 The nickel dendrite electrolysis hydrogen production electrode prepared in this comparative example has a less directional morphology compared to the dendritic morphology of *Juniperus chinensis*, with uncontrolled excessive growth of lateral branches. Figure 15 Comparative Example 1 can be obtained at 500 mA / cm 2 and 800 mA / cm 2 The hydrogen evolution overpotentials at the specified current densities were 350 mV and 393 mV. Furthermore, the comparative electrode exhibited dense, non-directional growth of nickel dendrites. Moreover, this comparative electrode showed more pronounced lateral branch development of the dendrites compared to the three examples, which not only weakened the catalytic activity but also affected the stability of the dendritic electrode. These results demonstrate the crucial role of alternating ultrasound in the "magnetic field + alternating ultrasound" coupled-assisted electrodeposition process in suppressing uncontrolled lateral branch development and regulating the ordered growth of the dendritic catalyst in the production of juniper-shaped nickel dendrite electrodes from Xinjiang.

[0107] Comparative Example 2

[0108] A method for preparing an electrode for hydrogen production by water electrolysis includes the following steps:

[0109] The difference between this comparative example and Example 1 is that only a magnetic field is added during the electrodeposition process, without the addition of ultrasound; the remaining steps are the same as in Example 1.

[0110] This comparative example prepared an electrolytic water electrolysis hydrogen production electrode, which was prepared by... Figure 12 It can be clearly observed that its morphology is irregular, and the lateral branches exhibit uncontrolled excessive growth and uneven distribution, indicating that the electrode does not exhibit the characteristics of juniper dendrites without the assistance of alternating ultrasound. Figure 15 Comparative Example 2 shows that at 500 mA / cm 2 and 800 mA / cm 2 The hydrogen evolution overpotentials of this electrode at the given current density were 364 mV and 405 mV. This comparative example's overpotential is better than that of Comparative Example 3, but still significantly lower than that of Examples 1-3. These results demonstrate the crucial role of alternating ultrasound in controlling the uniform distribution of nickel dendrites and suppressing uncontrolled lateral branch growth in the preparation of juniper-like nickel dendrites in Xinjiang using this "magnetic field + alternating ultrasound" coupled electrodeposition technique.

[0111] Comparative Example 3

[0112] A method for preparing an electrode for hydrogen production by water electrolysis includes the following steps:

[0113] The difference between this comparative example and Example 1 is that only alternating ultrasonic waves are added during the electrodeposition process, without the addition of a magnetic field for assistance; the remaining steps are the same as in Example 1.

[0114] This comparative example prepared an electrolytic water electrolysis hydrogen production electrode, which was prepared by... Figure 13 It can be clearly observed that its surface is smooth and has a porous film-like structure, indicating that the electrode does not exhibit the characteristics of juniper dendrites when only alternating ultrasound is applied without the assistance of a magnetic field. Figure 15 Comparative Example 3 shows that at 500 mA / cm 2 and 800 mA / cm 2 The hydrogen evolution overpotentials of this electrode at the given current density were 420 mV and 465 mV. These results demonstrate that the addition of a magnetic field in the "magnetic field + alternating ultrasound" coupled-assisted technique plays a crucial role in promoting the growth of nickel dendrites in the preparation of juniper-like nickel dendrites from Xinjiang. Furthermore, this promoting effect is non-directional, as seen in Comparative Examples 1 and 2.

[0115] Comparative Example 4

[0116] A method for preparing an electrode for hydrogen production by water electrolysis includes the following steps:

[0117] The difference between this comparative example and Example 1 is that no magnetic field or alternating ultrasonic waves are added during the electrodeposition process, while the remaining steps are the same as in Example 1.

[0118] This comparative example prepared an electrolytic water electrolysis hydrogen production electrode, which was prepared by... Figure 14 It can be clearly observed that, compared with Example 1, the surface of the electrode is smooth and presents a porous membrane layer, indicating that the electrode does not exhibit the characteristics of juniper dendrites under conditions without magnetic field and alternating ultrasonic assistance. Figure 15 Comparative Example 4 shows that at 500 mA / cm 2 and 800 mA / cm 2 The hydrogen evolution overpotentials of this electrode at the given current density were 426 mV and 508 mV. Combined with Comparative Examples 1, 2, and 3, these results demonstrate the important role of "magnetic field + alternating ultrasound" coupled electrodeposition in the preparation of juniper-like nickel dendrites in Xinjiang.

[0119] Comparative Example 5

[0120] A method for preparing an electrode for hydrogen production by water electrolysis includes the following steps:

[0121] The difference between this comparative example and Example 1 is that electrodeposition was not performed; all other steps, such as cleaning and testing, are the same as in Example 1. For ease of comparison, the experimental data obtained from this comparative example are used as a blank control group in the plot. Figure 15 In Comparative Example 5, experimental results show that the foamed nickel electrode without juniper dendrites exhibits performance at 10 mA / cm². 2 500 mA / cm 2The hydrogen evolution overpotentials at the current densities were 226 mV and 500 mV, respectively.

[0122] Figure 15 The LSV curves of Examples 1-3 and Comparative Examples 1-5 are shown as comparison graphs demonstrating the hydrogen production performance.

[0123] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of the present invention.

Claims

1. A method for preparing a juniper dendritic nickel dendrite electrolysis water-to-hydrogen electrode, characterized in that, Includes the following steps: Under magnetic field and alternating ultrasonic conditions, a nickel dendrite electrolytic hydrogen production electrode with juniper dendrites is obtained by electrodeposition in a nickel-containing electroplating solution using a metal substrate as the cathode; the metal substrate is in a magnetic field, and the direction of the magnetic field is parallel to the surface of the metal substrate. The magnetic field is generated by N-pole and S-pole magnets positioned on both sides of the metal substrate and parallel to the thickness surface of the metal substrate. The parameters of the alternating ultrasound are: ultrasound with a time of 25-35 s and a frequency of 15-25 kHz and ultrasound with a time of 25-35 s and a frequency of 35-45 kHz are alternated. The surface magnetic field strength of the magnet is 8000-10000 Gs, and the distance between the two magnets is 2-30 cm; The concentration of nickel ions in the nickel-containing electroplating solution is 0.1-1 mol / L; The pH of the nickel-containing electroplating solution is 1-5.5; The electrodeposition current is 50-180 mA / cm. 2 Direct current, for 3-20 minutes; The nickel-containing electroplating solution also includes a pH buffer; The molar ratio of nickel ions to pH buffer in the nickel-containing electroplating solution is 1:1 to 1:1.5; The pH buffer is an ammonium salt; The ammonium salt is one or more of ammonium sulfate, ammonium bisulfate, ammonium chloride, and ammonium nitrate; The distance between the working anode and working cathode of the electrodeposition is 2-10 cm.

2. The method for preparing the juniper dendritic nickel dendrite electrolysis water-to-hydrogen electrode according to claim 1, characterized in that, The parameters of the alternating ultrasound are: ultrasound with a time of 30 s and a frequency of 20 kHz and ultrasound with a time of 30 s and a frequency of 40 kHz are alternated.

3. The method for preparing the juniper dendritic nickel dendrite electrolysis water-to-hydrogen electrode according to claim 1, characterized in that, The metal substrate is a metal sheet, foil, mesh, or porous metal substrate. The metal substrate undergoes pretreatment before electrodeposition.

4. The method for preparing the juniper dendritic nickel dendrite electrolysis water-to-hydrogen electrode according to claim 3, characterized in that, The metal sheet, foil, or mesh is Ni foil, Ni mesh, Ti foil, Ti mesh, stainless steel sheet, or stainless steel mesh; The porous metal substrate is nickel foam, iron foam, copper foam, or nickel felt. When the metal substrate is a metal sheet, foil, or mesh, the pretreatment is sanding, cleaning, and drying; when the metal substrate is a porous metal substrate, the pretreatment is pickling, cleaning, and drying.

5. The method for preparing the juniper dendritic nickel dendrite electrolysis water-to-hydrogen electrode according to claim 1, characterized in that, The temperature of the nickel-containing electroplating solution is 40-70℃.

6. The method for preparing the juniper dendritic nickel dendrite electrolysis water-to-hydrogen electrode according to claim 1, characterized in that, The nickel-containing electroplating solution contains nickel salts, which are one or more of nickel sulfate, nickel chloride, nickel nitrate, nickel acetate, nickel oxalate, nickel perchlorate, nickel chlorate, and nickel bromide. The working anode is an inert conductor; The inert conductor is a carbon rod.

7. The juniper dendritic nickel dendrite electrolysis hydrogen production electrode prepared by the preparation method according to any one of claims 1-6.

8. The application of the juniper dendritic nickel dendrite electrolysis hydrogen production electrode according to claim 7 in water electrolysis hydrogen production.

9. The application according to claim 8, characterized in that, The juniper dendritic nickel dendrite electrolytic water production electrode serves as the cathode in the electrolytic water production process. The current density for hydrogen production via water electrolysis is 10-1000 mA / cm². 2 ; The electrolyte used in the electrolysis of water to produce hydrogen is an alkaline electrolyte. The alkaline electrolyte is a 1-8 mol / L KOH solution.

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