Self-breathing hydrogen evolution electrode with bubble directional transmission function and preparation method and application thereof

Abstract

The application belongs to the technical fields of water electrolysis hydrogen production and catalysis, and discloses a self-breathing hydrogen evolution electrode with bubble directional transmission function and a preparation method and application thereof, which comprises the following steps: dissolving a catalyst precursor salt, a complexing agent and a structure directing agent in deionized water to form a uniform mixed solution, performing a hydrothermal reaction, performing washing, filtering and drying treatment to obtain a catalyst precursor, converting the catalyst precursor into a hydrogen evolution catalyst material through heat treatment, and loading the hydrogen evolution catalyst material on the surface of a conductive substrate to form a catalytically active layer; uniformly depositing templates with different particle sizes on the surface of the catalytically active layer, removing the templates, and obtaining a gas guiding layer with a gradient pore size distribution; processing the surface of the gas guiding layer through laser scanning to form a bionic vein-shaped gas guiding channel network, performing modification treatment, constructing a wettability gradient structure, and obtaining a bionic self-breathing hydrogen evolution electrode with bubble directional transmission function. The application significantly reduces the bubble coverage rate of the electrode surface and improves the utilization efficiency of catalytically active sites.

Description

Technical Field

[0001] This invention belongs to the field of water electrolysis for hydrogen production and catalysis technology, and relates to a self-breathing hydrogen evolution electrode with bubble directional transport function, its preparation method and application. Background Technology

[0002] Hydrogen energy, as a clean and efficient secondary energy source, is an important component of the new energy industry system. Electrolysis of water to produce hydrogen is currently one of the core technologies for large-scale, high-quality hydrogen production, possessing numerous advantages such as high hydrogen purity, clean processes, and compatibility with renewable energy consumption. It is widely used in various fields including chemical engineering, energy, and energy storage. The electrolyzer, as the core equipment in water electrolysis for hydrogen production, directly determines the efficiency of the electrolysis reaction, energy consumption level, and equipment operational stability through the performance of its cathode hydrogen evolution electrode. The development of high-performance hydrogen evolution electrodes is crucial for enhancing the industrial value of water electrolysis for hydrogen production.

[0003] Currently, the cathode electrodes of industrially scaled electrolyzers commonly use nickel-based, nickel-iron-based, and their derivative modified electrodes. These electrodes offer advantages such as controllable cost, good conductivity, suitability for industrial conditions, and strong stability, making them the mainstream choice for existing water electrolysis hydrogen production systems and meeting the production needs of electrolytic hydrogen under normal operating conditions. However, as water electrolysis hydrogen production upgrades towards high current density, high efficiency, and low energy consumption for industrial applications, the industry generally adopts 500~2000 mA / cm² electrodes. 2 Under high current density operating conditions, the technical drawbacks of existing nickel-based and nickel-iron-based hydrogen evolution electrodes have gradually become apparent, severely restricting the operating performance of electrolyzers under high load conditions.

[0004] Under high current density operating conditions, the electrochemical reaction rate on the electrode surface increases significantly, and a large number of hydrogen bubbles are continuously and rapidly generated at the cathode. These large numbers of hydrogen bubbles cannot be desorbed and discharged in time, easily accumulating and adhering to the electrode surface to form a continuous bubble cover layer. This leads to a series of chain reactions and negative effects: First, the bubble layer directly blocks the catalytic active sites on the electrode surface, significantly reducing the effective reaction area and lowering the electrochemical reaction efficiency. Second, bubble adhesion blocks the mass transfer channels on the electrode surface, causing localized electrolyte transport and diffusion obstruction, resulting in a significant decrease in the mass transfer efficiency of the reaction system. Third, the continuous presence of the gas-liquid interface significantly increases the interfacial ohmic impedance, exacerbating concentration polarization in the electrolysis system and directly leading to an increase in electrolysis overpotential. Fourth, the continuous generation, adhesion, and peeling of bubbles repeatedly impact the catalytic layer on the electrode surface, easily causing cracking and detachment of the catalytic layer under long-term operation, leading to electrode performance degradation and shortened service life. Ultimately, this results in a significant increase in overall energy consumption and a decrease in operational stability of the electrolyzer, greatly limiting the industrial application of high current density water electrolysis for hydrogen production.

[0005] To address the issues of low hydrogen evolution efficiency and high energy consumption, existing improvement technologies primarily focus on optimizing electrode catalytic performance. This is mainly achieved through developing highly active catalysts, controlling the electrode microstructure to increase specific surface area, and optimizing electrode material ratios to improve overall conductivity, thereby enhancing the intrinsic hydrogen evolution catalytic capacity of the electrode itself. While these approaches can reduce the overpotential of the hydrogen evolution reaction and increase the reaction activity per unit area to some extent, their optimization dimensions are relatively singular, exhibiting significant limitations. Existing technologies generally neglect the crucial impact of hydrogen bubble transport and desorption behavior on the electrolysis system under high current density conditions, and research on active control technologies for directional bubble migration, rapid desorption, and efficient discharge is severely lacking.

[0006] Extensive experimental and industrial operation data show that under normal low current density conditions, electrode catalytic activity is the main factor limiting electrolysis efficiency; however, under conditions of 500–2000 mA / cm², the efficiency is significantly higher. 2 Under high current density industrial conditions, the mass transfer resistance and interfacial impedance caused by bubble accumulation on the electrode surface have replaced catalytic activity as the core bottleneck restricting the improvement of the ultimate efficiency of electrolyzers and causing high industrial energy consumption. Existing technical solutions that only optimize catalytic performance cannot fundamentally solve the problems of bubble accumulation and mass transfer obstruction under high current density, and are difficult to adapt to the industrial development needs of high-power, high-load water electrolysis for hydrogen production.

[0007] In summary, current industrial hydrogen evolution electrodes suffer from numerous problems under high current density conditions, including difficulty in bubble desorption, high interfacial impedance, low mass transfer efficiency, high energy consumption, and poor stability. Existing technologies lack effective means to control the interfacial behavior of hydrogen bubbles. Therefore, developing a novel hydrogen evolution electrode capable of actively controlling the directional migration of hydrogen bubbles and achieving rapid bubble desorption and discharge, thereby overcoming the technical bottleneck of bubble transport resistance under high current density, is of significant practical and engineering value for improving the efficiency of water electrolysis for hydrogen production, reducing industrial operating energy consumption, extending electrode lifespan, and promoting the large-scale industrial application of high-power water electrolysis for hydrogen production technology. Summary of the Invention

[0008] The purpose of this invention is to provide a self-breathing hydrogen evolution electrode with bubble directional transport function, its preparation method and application, to solve the problems of existing water electrolysis hydrogen evolution electrodes such as severe bubble coverage, low mass transfer efficiency, decreased utilization of active sites and insufficient long-term operational stability under high current density operating conditions.

[0009] To achieve the above objectives, the present invention employs the following technical solution: A method for preparing a self-breathing hydrogen evolution electrode with bubble directional transport function, comprising: The catalyst precursor salt, complexing agent and structure directing agent are dissolved in deionized water to form a homogeneous mixed solution. The homogeneous mixed solution was subjected to a hydrothermal reaction, followed by washing, filtration and drying to obtain the catalyst precursor; The catalyst precursor is converted into a hydrogen evolution catalyst material through heat treatment and loaded onto the surface of a conductive substrate to form a catalytic active layer. Templates of different particle sizes are uniformly deposited on the surface of the catalytic active layer, and the templates are removed by heat treatment or chemical etching to obtain a gas-conducting layer with a gradient pore size distribution. By processing the surface of the gas guide layer with laser scanning, a biomimetic leaf vein-like gas guide channel network is formed and modified to construct a wettability gradient structure, thereby obtaining a biomimetic self-breathing hydrogen evolution electrode with bubble directional transport function.

[0010] Furthermore, in the homogeneous mixed solution, the concentration of the catalyst precursor salt is 0.01~2 mol / L, the molar ratio of the complexing agent to the metal ions is 1:20~20:1, and the concentration of the structure directing agent is 0.001~1 mol / L; The catalyst precursor salt is one or more of nickel salt, iron salt, cobalt salt, molybdenum salt, copper salt, manganese salt, and tungsten salt, and the precursor salt is one or more of chloride salt, nitrate salt, sulfate salt, and acetate salt; The complexing agent is one or more of citric acid, sodium citrate, ethylenediaminetetraacetic acid, sodium gluconate, and potassium sodium tartrate. The structure-directing agent is one or more of urea, hexamethylenetetramine, polyvinylpyrrolidone, and hexadecyltrimethylammonium bromide.

[0011] Furthermore, the hydrothermal reaction temperature is 80~220℃, and the reaction time is 2~48 h; The heat treatment atmosphere is air, nitrogen, argon, hydrogen, or a mixture of hydrogen and argon. The heat treatment temperature is 250~700℃, and the holding time is 0.5~10 h.

[0012] Furthermore, the conductive substrate is one or more of the following: nickel foam, nickel mesh, titanium mesh, stainless steel mesh, copper mesh, carbon cloth, and carbon paper.

[0013] 5. The method for preparing a self-breathing hydrogen evolution electrode with bubble directional transport function according to claim 1, characterized in that the templates of different particle sizes include polystyrene microspheres, polymethyl methacrylate microspheres, silica microspheres and soluble salt particles; The pore size of the gas-conducting layer is 0.1~1000 μm, and the thickness of the gas-conducting layer is 10~1000 μm.

[0014] Furthermore, lasers include femtosecond lasers, nanosecond lasers, and picosecond lasers; The laser power is 1~100 W, the scanning speed is 10~5000 mm / s, and the scanning spacing is 5~500 μm; The biomimetic leaf vein-like air-guiding channel network includes a main vein air-guiding channel and a lateral vein air-guiding channel, with the included angle between the main vein air-guiding channel and the lateral vein air-guiding channel being 10°~80°. The width of the main vein air-conducting channel is 100~2000 μm and the depth is 20~1000 μm, while the width of the lateral vein air-conducting channel is 10~500 μm and the depth is 10~500 μm.

[0015] Furthermore, the modification treatments include plasma treatment, ultraviolet ozone treatment, and low surface energy modifier treatment; The low surface energy modifier is one or more of fluorosilanes, perfluoropolyethers, polytetrafluoroethylene and fluoropolymers.

[0016] Furthermore, the wettability gradient structure is constructed by combining hydrophilic and hydrophobic modified regions, with the hydrophilic region having a contact angle of 0°~60° and the hydrophobic region having a contact angle of 90°~170°.

[0017] A self-breathing hydrogen evolution electrode with bubble directional transport function prepared by the aforementioned method has an electrode thickness of 50~5000 μm.

[0018] Applications of the self-breathing hydrogen evolution electrode with bubble directional transport function in alkaline water electrolysis devices, anion exchange membrane water electrolysis devices, and high-pressure water electrolysis hydrogen production systems.

[0019] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for preparing a self-breathing hydrogen evolution electrode with bubble-directed transport function. First, a highly active catalytic layer is constructed on the surface of a conductive substrate. Then, a gas-conducting layer with a pore size gradient is constructed outside the catalytic layer using a sacrificial template method. To further reduce bubble migration resistance, a biomimetic leaf vein-like gas-conducting network structure is formed on the surface of the gas-conducting layer using laser micro-nano processing technology. The main vein channel and the lateral vein channel are interconnected, forming a multi-level gas-conducting network. To achieve selective transport of bubbles and electrolyte, surface wettability control technology is further employed to construct a wettability gradient structure on the electrode surface, gradually changing from a superhydrophilic region to a hydrophobic region. This structure promotes continuous electrolyte wetting of the catalytic layer while driving hydrogen bubbles to migrate towards the leaf vein gas-conducting channels, achieving synergistic control of continuous electrolyte wetting and rapid hydrogen expulsion. The electrolyte can be rapidly replenished to the catalytic reaction interface, while the generated hydrogen bubbles preferentially migrate to the outside of the electrode along the gas-conducting channels, thus forming a "self-breathing mechanism" similar to the gas exchange process in plant leaves. This effectively reduces the interfacial charge transfer impedance, improves electron and mass transport efficiency, and simultaneously ensures high catalytic activity and long-term operational stability. This invention achieves active collection, directional transport, and rapid desorption of hydrogen bubbles during hydrogen evolution by constructing a multi-level structure of "catalytic active layer - gradient pore size gas-conducting layer - biomimetic leaf vein gas-conducting network." Compared to traditional random gas evolution methods, the capillary pressure difference generated by the pore size gradient and the synergistic effect of the biomimetic leaf vein gas-conducting channels significantly reduce the bubble coverage on the electrode surface, effectively alleviating the mass transfer limitation problem under high current density conditions and improving the utilization efficiency of catalytic active sites. Compared to traditional nickel foam electrodes, electrodeposited electrodes, and conventional supported catalytic electrodes, this invention can achieve active control of bubble behavior without complex flow field design. The template construction, laser micromachining, and surface wettability control processes employed all possess advantages such as simple processes, good repeatability, and ease of large-scale production. They can be widely applied to alkaline water electrolysis, anion exchange membrane (AEM) water electrolysis, and high-voltage water electrolysis hydrogen production systems, providing a new technical approach for the development of high-current-density, low-energy-consumption industrial water electrolysis hydrogen production electrodes. Furthermore, the biomimetic leaf vein gas-conducting structure proposed in this invention is not dependent on a specific catalytic material system and is applicable to various hydrogen evolution catalysts, including nickel-based alloys, nickel-molybdenum alloys, nickel-iron alloys, metal phosphides, high-entropy alloys, and their derivatives. It exhibits good versatility and scalability, providing new structural design ideas for the design of next-generation high-performance self-breathing electrodes.

[0020] Furthermore, by optimizing the catalyst system of multi-element transition metal salts such as nickel, iron, and cobalt, highly active and stable hydrogen evolution catalytic sites can be constructed, adapting to the operational requirements of industrial water electrolysis. Controllable catalyst precursor salt concentrations and the ratio of complexing agents to structure-directing agents allow for precise control of the crystallite size, morphology, and dispersion uniformity of the catalyst precursor, effectively avoiding catalyst agglomeration and uneven distribution of active sites, and significantly improving the specific surface area and intrinsic catalytic activity of the catalyst layer. Simultaneously, the wide range of selectable raw materials broadens the preparation adaptability, allowing for flexible adjustment of the material system according to different electrolysis conditions, balancing electrode catalytic performance with preparation flexibility, and ensuring the stability and consistency of electrode performance under different process conditions.

[0021] Furthermore, precise hydrothermal temperature and time parameters enable uniform growth and complete crystallization of the catalyst precursor, ensuring a regular precursor structure and uniform performance, laying the foundation for subsequent high-performance catalyst layer formation. Diverse heat treatment atmospheres can specifically control the phase composition, defect concentration, and electronic structure of the catalyst material, optimizing the hydrogen evolution reaction kinetics. At the same time, controllable heat treatment temperature and holding time enable full crystallization and stable formation of the precursor, effectively enhancing the bonding strength between the catalyst layer and the conductive substrate, avoiding the problem of catalyst layer detachment and failure during long-term electrolysis, significantly improving the operational stability and service life of the electrode, and adapting to industrial scenarios with high current density and long-term continuous operation.

[0022] Furthermore, substrates such as nickel foam, nickel mesh, and carbon cloth possess excellent conductivity, mechanical strength, and alkali corrosion resistance, effectively reducing the overall ohmic impedance of the electrode and ensuring rapid electron transport under high current conditions, thus avoiding energy loss caused by excessive impedance of the conductive substrate. Simultaneously, various porous, mesh, and fibrous substrates exhibit good gas and liquid permeability, providing basic channels for electrolyte penetration and bubble diffusion. These materials synergize with subsequent gradient gas-conducting layers and biomimetic gas-conducting channels, further enhancing the electrode's mass transfer and gas-conducting capabilities. The availability of multiple substrate options allows for adaptation to different electrolytic cell structures and operating environments, significantly improving the electrode's engineering adaptability and application scope.

[0023] Furthermore, by utilizing controllable deposition and removal processes of templates with different particle sizes, a porous gas-conducting layer structure with a gradient pore size distribution is precisely constructed. The gradient pore size structure can form progressively progressive bubble transport channels. The small pore size structure is conducive to the rapid capture of tiny hydrogen bubbles and the reduction of bubble nucleation resistance, while the large pore size structure can accelerate bubble aggregation and rapid discharge, effectively solving the problems of bubble blockage and poor transport in traditional homogeneous porous structures. The controllable thickness and pore size of the gas-conducting layer can match the bubble generation rate under different current densities, achieving a dynamic balance between bubble generation, aggregation, and desorption, further enhancing the active gas-conducting capability of the electrode, significantly improving the gas-liquid mass transfer environment on the electrode surface under high current density, and reducing concentration polarization and interfacial impedance.

[0024] Furthermore, high-precision laser scanning can construct a regular, uniform, and controllable main-side vein composite air-guiding channel network. The branching structure of the biomimetic leaf veins matches the transmission law of bubbles from local aggregation, gradual convergence, and directional discharge. The main vein channel enables rapid bubble guidance and transportation, while the side vein channel fully covers and collects tiny bubbles on the electrode surface, eliminating transmission dead zones. Precise laser power, scanning speed, and spacing parameters ensure the accuracy of channel forming and avoid channel structural defects. At the same time, the controllable channel angle, width, and depth dimensions can adapt to large-scale, high-rate bubble generation scenarios under high current density, significantly improving the efficiency of bubble directional migration and rapid desorption, and completely solving the problems of local bubble accumulation and desorption lag in traditional electrodes.

[0025] Furthermore, plasma and ultraviolet ozone treatments can precisely control the microstructure and surface energy of the electrode surface. Combined with low surface energy modifications such as fluorosilanes and fluoropolymers, the adhesion between hydrogen bubbles and the electrode surface can be significantly reduced, weakening the bubble adhesion effect and facilitating rapid bubble desorption. Multiple modification processes can be flexibly combined to ensure that the original hydrogen evolution catalytic activity of the catalyst layer is not destroyed, while a low-adhesion gas-conducting interface is stably constructed, further enhancing the electrode's self-breathing gas-conducting function. At the same time, the modified layer structure is stable and resistant to electrochemical corrosion, maintaining excellent bubble desorption performance for a long time and ensuring long-term efficient and stable operation of the electrode.

[0026] Furthermore, a precise interfacial wettability gradient structure is constructed. The hydrophilic region efficiently adsorbs the electrolyte, ensuring a sufficient supply of reaction medium to the electrode surface and preventing a decrease in reaction efficiency due to localized electrolyte deficiency, thus enhancing the electrochemical reaction process. The hydrophobic region significantly reduces bubble adhesion, guiding bubbles to migrate directionally towards the hydrophobic, highly conductive region. Based on the wettability difference, a spontaneous bubble transport driving force is formed, enabling active directional desorption and rapid expulsion of bubbles without external assistance. This hydrophilic-hydrophobic composite gradient structure achieves a two-way synergy of "rapid electrolyte replenishment and efficient bubble desorption," fundamentally resolving the contradiction between mass transfer and gas conduction under high current density at the interfacial mechanism, and significantly improving the overall operating efficiency of the electrolysis system.

[0027] This invention also provides a self-breathing hydrogen evolution electrode with bubble-directed transport function prepared by the above-described method. The controllable electrode thickness balances electrode structural stability, catalytic loading, and mass transfer efficiency. A suitable electrode thickness ensures the complete formation of the catalytic active layer, gradient gas-conducting layer, and biomimetic gas-conducting channel, guaranteeing a sufficient number of catalytic active sites. Simultaneously, it avoids problems such as increased electrolyte transport resistance, excessively long bubble discharge paths, and increased electron transport losses caused by excessively thick electrodes. It also avoids the defects of insufficient structural strength, missing functional layers, and shortened service life caused by excessively thin electrodes. This thickness parameter range is adaptable to various industrial electrolysis conditions, effectively balancing electrode catalytic performance, structural stability, and energy consumption, ensuring optimal overall electrode performance.

[0028] This invention also provides an application of the aforementioned self-breathing hydrogen evolution electrode with bubble directional transport function in alkaline water electrolysis devices, anion exchange membrane water electrolysis devices, and high-pressure water electrolysis hydrogen production systems. During the hydrogen evolution process, hydrogen bubbles generated on the electrode surface first enter the gradient pore size gas guiding layer. Due to the capillary pressure difference generated by the gradually increasing pore size, the bubbles preferentially migrate towards the larger pore area. Subsequently, the bubbles enter the biomimetic leaf vein lateral vein channel and finally converge into the main vein channel and exit the electrode surface. Because the bubbles can quickly detach from the electrode along a preset path, the bubble coverage and interfacial mass transfer resistance are significantly reduced, improving the hydrogen evolution efficiency and operational stability of the electrode under high current density conditions. Detailed Implementation

[0029] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0030] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0031] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0032] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0033] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0034] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0035] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0036] The present invention will now be described in further detail: This invention provides a self-breathing hydrogen evolution electrode with bubble directional transport function, its preparation method, and its application, specifically including the following steps: Step (1): Dissolve the catalyst precursor salt, complexing agent and structure directing agent in deionized water to form a homogeneous mixed solution; Step (2): The homogeneous mixed solution obtained in step (1) is transferred to a reaction vessel for hydrothermal reaction. After the reaction is completed, the catalyst precursor is obtained by washing, filtering and drying. Step (3): The catalyst precursor obtained in step (2) is converted into a hydrogen evolution catalyst material by heat treatment and loaded onto the surface of a conductive substrate to form a catalytic active layer. Step (4): Polystyrene microspheres, polymethyl methacrylate microspheres, silica microspheres or soluble salt particles are uniformly deposited on the surface of the catalytic active layer as sacrificial templates. The templates are removed by heat treatment or chemical etching to obtain a gas-conducting layer with a gradient pore size distribution. Step (5): Use femtosecond laser, nanosecond laser or picosecond laser to scan and process a biomimetic leaf vein-like air guiding channel network on the surface of the air guiding layer; Step (6): Using plasma treatment, ultraviolet ozone treatment or low surface energy modifier treatment, a wettability gradient structure is constructed on the electrode surface to obtain a biomimetic self-breathing hydrogen evolution electrode with bubble directional transport function.

[0037] Preferably, the catalyst precursor salt in step (1) is one or more of nickel salt, iron salt, cobalt salt, molybdenum salt, copper salt, manganese salt and tungsten salt, and the precursor salt is one or more of chloride salt, nitrate salt, sulfate salt and acetate salt, with a concentration of 0.01~2 mol / L.

[0038] Preferably, the complexing agent in step (1) is one or more of citric acid, sodium citrate, ethylenediaminetetraacetic acid, sodium gluconate and potassium sodium tartrate, and the molar ratio of the complexing agent to the metal ion is 1:20 to 20:1.

[0039] Preferably, the structure directing agent in step (1) is one or more of urea, hexamethylenetetramine, polyvinylpyrrolidone and hexadecyltrimethylammonium bromide, with a concentration of 0.001~1 mol / L.

[0040] Preferably, the hydrothermal reaction temperature in step (2) is 80~220℃, the reaction time is 2~48 h, and the reactor filling rate is 20%~80%.

[0041] Preferably, the heat treatment atmosphere in step (3) is air, nitrogen, argon, hydrogen or a mixture of hydrogen and argon, the heat treatment temperature is 250~700℃, and the holding time is 0.5~10 h.

[0042] Preferably, the gradient pore structure in step (4) is constructed from templates of different particle sizes, with a pore size range of 0.1~1000 μm; and the thickness of the gas-conducting layer is 10~1000 μm.

[0043] Preferably, the biomimetic leaf vein-like air-guiding channel network in step (5) includes a main vein air-guiding channel and a lateral vein air-guiding channel. The main vein air-guiding channel has a width of 100~2000 μm and a depth of 20~1000 μm; the lateral vein air-guiding channel has a width of 10~500 μm and a depth of 10~500 μm; and the included angle between the main vein air-guiding channel and the lateral vein air-guiding channel is 10°~80°.

[0044] Preferably, the laser power in step (5) is 1~100 W, the scanning speed is 10~5000 mm / s, and the scanning spacing is 5~500 μm.

[0045] Preferably, the wettability gradient in step (6) is constructed by the joint construction of hydrophilic modified region and hydrophobic modified region; the contact angle of the hydrophilic region is 0°~60°; and the contact angle of the hydrophobic region is 90°~170°.

[0046] Preferably, the low surface energy modifier in step (6) is one or more of fluorosilane, perfluoropolyether, polytetrafluoroethylene and fluoropolymer.

[0047] Preferably, the conductive substrate is one or more of the following: nickel foam, nickel mesh, titanium mesh, stainless steel mesh, copper mesh, carbon cloth, or carbon paper.

[0048] The present invention also provides a self-breathing hydrogen evolution electrode with bubble directional transport function prepared by the above preparation method, wherein the total thickness of the electrode is 50~5000 μm.

[0049] The present invention also provides an application of the above-mentioned self-breathing hydrogen evolution electrode with bubble directional transport function in alkaline water electrolysis devices, anion exchange membrane water electrolysis devices, and high-pressure water electrolysis hydrogen production systems.

[0050] The technical solution of the present invention will be further described in detail below through specific embodiments: Example 1: This embodiment takes the fabrication of a biomimetic leaf vein structure NiMo self-breathing hydrogen evolution electrode as an example. The specific steps are as follows: 1) Prepare 100 mL of a mixed solution consisting of 0.08 mol / L nickel sulfate, 0.04 mol / L ammonium molybdate, 0.15 mol / L urea and 0.05 mol / L sodium citrate.

[0051] 2) The above mixed solution was transferred to a 150 mL polytetrafluoroethylene-lined reactor, with a solution filling rate of 66.7%, and hydrothermally reacted at 160 °C for 8 h. After the reaction, the mixture was naturally cooled to room temperature, and the nickel foam substrate was removed. It was ultrasonically cleaned three times with deionized water and anhydrous ethanol, and then vacuum dried at 60 °C for 6 h to obtain a nickel foam electrode supported on the Ni-Mo precursor.

[0052] 3) The foamed nickel electrode loaded with Ni-Mo precursor was placed in a hydrogen-argon mixed atmosphere (5% H2 / 95% Ar) for heat treatment. The heating rate was 5 ℃ / min, the holding temperature was 450 ℃, and the holding time was 2 h. After natural cooling, the NiMo catalytic active layer was obtained.

[0053] 4) Polystyrene microspheres with particle sizes of 20 μm, 100 μm, and 300 μm were mixed at a mass ratio of 1:2:3 and uniformly sprayed onto the surface of the NiMo catalyst layer, and dried at 80 °C for 4 h. Subsequently, the mixture was treated at 350 °C for 2 h under a nitrogen atmosphere to remove the template, forming a gradient pore size gas-conducting layer with a gradual transition from small pores to large pores.

[0054] 5) A biomimetic leaf vein structure was fabricated on the surface of the air-conducting layer using a femtosecond laser. The main vein channel has a width of 800 μm and a depth of 300 μm; the lateral vein channel has a width of 150 μm and a depth of 80 μm; the angle between the main vein and lateral vein air-conducting channels is 45°. The femtosecond laser power is 15 W, the scanning speed is 1200 mm / s, and the scanning interval is 50 μm.

[0055] 6) The central region of the electrode was treated with oxygen plasma for 5 min to form a superhydrophilic surface; then, the leaf vein gas-conducting region was sprayed with a 1% (w / w) fluorosilane ethanol solution for 30 min. After drying, a wettability gradient structure was formed, in which the water contact angle of the catalytic region was about 8° and the contact angle of the leaf vein gas-conducting region was about 135°, finally obtaining a self-breathing hydrogen evolution electrode with a multi-level structure of "catalytic active layer - gradient pore size gas-conducting layer - biomimetic leaf vein gas-conducting network".

[0056] Example 2: The difference from Example 1 is that the catalyst precursor system in step (1) is 0.06 mol / L nickel nitrate, 0.02 mol / L iron nitrate and 0.02 mol / L cobalt nitrate, while the other steps remain unchanged.

[0057] After hydrothermal reaction and heat treatment, a NiFeCo composite catalyst layer was obtained. Then, according to steps (4) to (6) of Example 1, a gradient pore size gas guiding layer, a biomimetic leaf vein gas guiding network and a wettability gradient structure were constructed to prepare a biomimetic self-breathing NiFeCo hydrogen evolution electrode with bubble directional transport function.

[0058] Example 3: The difference from Example 1 is that the catalyst precursor system in step (1) is 0.02 mol / L ferric sulfate, 0.02 mol / L cobalt sulfate, 0.02 mol / L nickel sulfate, 0.02 mol / L copper sulfate and 0.02 mol / L manganese sulfate, while the other steps remain unchanged.

[0059] A FeCoNiCuMn multi-element alloy catalyst layer is formed after electrodeposition and heat treatment.

[0060] Subsequently, following steps (4) to (6) of Example 1, a gradient pore size air-conducting layer, a biomimetic leaf vein air-conducting network, and a wettability gradient structure were constructed to prepare a biomimetic self-breathing FeCoNiCuMn hydrogen evolution electrode with bubble directional transport function.

[0061] Example 4: The difference from Example 1 is that the 95% porosity nickel foam substrate in step (2) is replaced with a 60-mesh nickel mesh, while the other steps remain unchanged. The resulting electrode still has a complete biomimetic leaf vein gas guiding network and gradient pore structure, thus preparing a biomimetic self-breathing hydrogen evolution electrode with bubble directional transport function.

[0062] Example 5: The difference from Example 1 is that the parameters of the leaf vein air-conducting structure in step (5) are adjusted. The width of the main vein air-conducting channel is adjusted to 1200 μm; the width of the lateral vein air-conducting channel is adjusted to 250 μm; and the angle between the main vein air-conducting channel and the lateral vein air-conducting channel is adjusted to 30°. The remaining steps remain unchanged, and a biomimetic self-breathing hydrogen evolution electrode with bubble directional transport function is prepared.

[0063] The biomimetic self-breathing hydrogen evolution electrode with bubble-directed transport function prepared in Example 1 of this invention was cut into rectangular samples with a length of 1.5 cm and a width of 1 cm. After being fixed with electrode clamps, it was used as the working electrode for hydrogen evolution performance testing. A three-electrode system was used for the test: the working electrode was the biomimetic self-breathing hydrogen evolution electrode with bubble-directed transport function prepared in Example 1 of this invention; the counter electrode was a platinum mesh; and the reference electrode was a mercuric oxide electrode. The electrolyte was a 1 mol / L KOH solution, and the effective test area of ​​the working electrode was 1 cm². 2 .

[0064] Hydrogen evolution performance was tested using linear sweep voltammetry (LSV) at a scan rate of 5 mV / s. A galvanostatic method was used at 1000 mA·cm⁻¹. -2 Stability tests were conducted under the specified conditions. The results showed that, compared with the control electrode without a biomimetic gas-conducting structure, the biomimetic self-breathing hydrogen evolution electrode with bubble directional transport function prepared in Example 1 of this invention has a lower hydrogen evolution overpotential and better long-term stability.

[0065] Electrochemical data were measured using linear voltammetry and electrochemical impedance spectroscopy. The linear voltammetry scan rate was 5 mV / s, the electrochemical impedance spectroscopy test potential was -1.3 V (vs. Hg / HgO), the electrochemical amplitude was 10 mV, and the frequency range was 10. 6 ~10 -1 Hz. The biomimetic self-breathing hydrogen evolution electrode with bubble directional transport function prepared in Example 1 of this invention operates at 1000 mA / cm². 2 The overpotential at the current density is 192 mV, which is superior to the 253 mV overpotential of the commercial noble metal catalyst Pt / C. Furthermore, the charge transfer resistance of the biomimetic self-breathing hydrogen evolution electrode with bubble-directed transport function prepared in Example 1 of this invention is lower than that of the electrode prepared by spraying commercial Pt / C onto nickel foam, indicating faster charge transfer between the interface and the electrolyte, demonstrating its high hydrogen evolution catalytic activity.

[0066] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a self-breathing hydrogen evolution electrode with bubble directional transport function, characterized in that, include: The catalyst precursor salt, complexing agent and structure directing agent are dissolved in deionized water to form a homogeneous mixed solution. The homogeneous mixed solution was subjected to a hydrothermal reaction, followed by washing, filtration and drying to obtain the catalyst precursor; The catalyst precursor is converted into a hydrogen evolution catalyst material through heat treatment and loaded onto the surface of a conductive substrate to form a catalytic active layer. Templates of different particle sizes are uniformly deposited on the surface of the catalytic active layer, and the templates are removed by heat treatment or chemical etching to obtain a gas-conducting layer with a gradient pore size distribution. By processing the surface of the gas guide layer with laser scanning, a biomimetic leaf vein-like gas guide channel network is formed and modified to construct a wettability gradient structure, thereby obtaining a biomimetic self-breathing hydrogen evolution electrode with bubble directional transport function.

2. The method for preparing the self-breathing hydrogen evolution electrode with bubble directional transport function according to claim 1, characterized in that, In the homogeneous mixed solution, the concentration of the catalyst precursor salt is 0.01~2 mol / L, the molar ratio of the complexing agent to the metal ions is 1:20~20:1, and the concentration of the structure directing agent is 0.001~1 mol / L. The catalyst precursor salt is one or more of nickel salt, iron salt, cobalt salt, molybdenum salt, copper salt, manganese salt, and tungsten salt, and the precursor salt is one or more of chloride salt, nitrate salt, sulfate salt, and acetate salt; The complexing agent is one or more of citric acid, sodium citrate, ethylenediaminetetraacetic acid, sodium gluconate, and potassium sodium tartrate. The structure-directing agent is one or more of urea, hexamethylenetetramine, polyvinylpyrrolidone, and hexadecyltrimethylammonium bromide.

3. The method for preparing the self-breathing hydrogen evolution electrode with bubble directional transport function according to claim 1, characterized in that, The hydrothermal reaction temperature is 80~220℃, and the reaction time is 2~48 h; The heat treatment atmosphere is air, nitrogen, argon, hydrogen, or a mixture of hydrogen and argon. The heat treatment temperature is 250~700℃, and the holding time is 0.5~10 h.

4. The method for preparing the self-breathing hydrogen evolution electrode with bubble directional transport function according to claim 1, characterized in that, The conductive substrate is one or more of the following: nickel foam, nickel mesh, titanium mesh, stainless steel mesh, copper mesh, carbon cloth, and carbon paper.

5. The method for preparing a self-breathing hydrogen evolution electrode with bubble directional transport function according to claim 1, characterized in that, Templates of different particle sizes include polystyrene microspheres, polymethyl methacrylate microspheres, silica microspheres, and soluble salt particles; The pore size of the gas-conducting layer is 0.1~1000 μm, and the thickness of the gas-conducting layer is 10~1000 μm.

6. The method for preparing a self-breathing hydrogen evolution electrode with bubble directional transport function according to claim 1, characterized in that, Lasers include femtosecond lasers, nanosecond lasers, and picosecond lasers; The laser power is 1~100 W, the scanning speed is 10~5000 mm / s, and the scanning spacing is 5~500 μm; The biomimetic leaf vein-like air-guiding channel network includes a main vein air-guiding channel and a lateral vein air-guiding channel, with the included angle between the main vein air-guiding channel and the lateral vein air-guiding channel being 10°~80°. The width of the main vein air-conducting channel is 100~2000 μm and the depth is 20~1000 μm, while the width of the lateral vein air-conducting channel is 10~500 μm and the depth is 10~500 μm.

7. The method for preparing a self-breathing hydrogen evolution electrode with bubble directional transport function according to claim 1, characterized in that, Modification treatments include plasma treatment, ultraviolet ozone treatment, and low surface energy modifier treatment; The low surface energy modifier is one or more of fluorosilanes, perfluoropolyethers, polytetrafluoroethylene and fluoropolymers.

8. The method for preparing a self-breathing hydrogen evolution electrode with bubble directional transport function according to claim 1, characterized in that, The wettability gradient structure is constructed by combining hydrophilic and hydrophobic modified regions. The contact angle of the hydrophilic region is 0°~60°, and the contact angle of the hydrophobic region is 90°~170°.

9. A self-breathing hydrogen evolution electrode with bubble directional transport function prepared by the preparation method according to any one of claims 1 to 8, characterized in that, The electrode thickness is 50~5000 μm.

10. The application of the self-breathing hydrogen evolution electrode with bubble directional transport function as described in claim 9 in alkaline water electrolysis devices, anion exchange membrane water electrolysis devices, and high-pressure water electrolysis hydrogen production systems.