Preparation method of multi-stage microstructure PEM electrolytic water hydrogen production membrane electrode

Abstract

The application relates to the technical field of hydrogen production by water electrolysis of a proton exchange membrane, and discloses a preparation method of a multistage microstructure PEM water electrolysis hydrogen production membrane electrode, which comprises four core steps of micron-level array printing aluminum foil preparation, nanostructure framework construction, catalyst loading and hot-pressing transfer printing film formation. The micron-level grid printing structure is combined with a bismuth oxide nanostructure framework to form a multistage microstructure catalyst carrier, so that the specific surface area of the membrane electrode is greatly improved; the catalyst is loaded by adopting a magnetron sputtering method, the combination strength of the catalyst and the carrier is enhanced, the amount of noble metal is reduced, and meanwhile, the carrier and the proton exchange membrane are efficiently combined through a transfer printing process. The prepared membrane electrode has a voltage as low as 1.6-1.8 V under a current density of 1 A / cm, the specific surface area is 1.5-2 times that of a traditional ordered nanostructure membrane electrode, the catalyst utilization rate is higher than 95%, the voltage does not obviously increase after continuous work for 6000 hours, the preparation process is compatible with conventional equipment, and the industrialized mass production is feasible.

Description

Technical Field

[0001] This invention relates to the field of proton exchange membrane (PEM) electrolysis of water for hydrogen production technology, specifically to a method for preparing a multi-level microstructure PEM electrolysis water electrolysis membrane electrode. Background Technology

[0002] PEM electrolysis for hydrogen production is a highly efficient and clean hydrogen production technology. The membrane electrode assembly (MEA), as the core component of the PEM electrolysis system, directly determines the number of active sites, reaction efficiency, and energy consumption level of the electrolysis reaction due to its specific surface area. Existing technologies have proposed a method for manufacturing ordered PEM electrolysis membrane electrodes without adhesive (CN202511124820.6). This method constructs an ultrathin ordered nanostructure carrier using physical vapor deposition, achieving efficient catalyst utilization. However, limited by the ultrathin monolayer nanostructure, it is impossible to further increase the specific surface area by increasing the thickness of the three-dimensional porous structure, thus creating a bottleneck in improving the membrane electrode performance.

[0003] Meanwhile, traditional membrane electrode preparation often employs chemical coating methods, which, while increasing the specific surface area by adding catalyst layer thickness, are prone to problems such as catalyst agglomeration, low bonding strength between the support and the proton exchange membrane, and low utilization rate of precious metal catalysts. While DC magnetron sputtering is environmentally friendly and suitable for industrial production, the films it produces are typically uniform and dense, making it difficult to construct surface nanostructures (WO / 2021 / 159680). Furthermore, low-melting-point bismuth targets are prone to overheating and deformation during magnetron sputtering, and single-scale micro / nanostructure supports cannot simultaneously achieve increased specific surface area and structural stability. These issues limit the performance improvement and industrial application of PEM water electrolysis membrane electrodes for hydrogen production.

[0004] To address the aforementioned issues, a method for preparing multi-level microstructure carriers that combines micron-level three-dimensional structures with nano-level structures has been developed. This method aims to significantly increase the specific surface area of ​​the membrane electrode while ensuring catalyst loading strength and membrane electrode structural stability, thus becoming a key direction for the development of PEM water electrolysis hydrogen production technology. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies, such as limited specific surface area improvement of PEM electrolysis water-to-hydrogen membrane electrodes, easy catalyst agglomeration, and low bonding strength between the support and the membrane. This invention provides a method for preparing a multi-level microstructured PEM electrolysis water-to-hydrogen membrane electrode. By constructing a micron- to nanon-level multi-level microstructured support, this invention significantly increases the specific surface area of ​​the membrane electrode. Simultaneously, it employs magnetron sputtering to load the catalyst and hot-pressing transfer to form the film, enhancing the bonding strength between the catalyst and the support, and between the support and the proton exchange membrane. This reduces energy consumption and the amount of precious metals used, improving the stability of the membrane electrode and its feasibility for industrial mass production.

[0006] To achieve the above-mentioned objectives, this invention provides a method for preparing a multi-level microstructured PEM water electrolysis hydrogen production membrane electrode, specifically including the following steps: Step 1: Preparation of micron-scale array printed aluminum foil The core of this step is to construct a three-dimensional mesh-like micron-scale printed structure on the surface of pure aluminum foil, providing three-dimensional support for the subsequent nanostructure framework and increasing the overall specific surface area.

[0007] Material selection: Use 1070, 1060, 1100 or 1235 series pure aluminum foil with a thickness of 15~50 μm. This type of aluminum foil has good plasticity and peelability, is suitable for printing and molding and can be peeled off without damage. Printing equipment and rollers: High-precision printing machine is adopted. The printing rollers are made of alloy steel with a hard chrome plating layer on the surface. The roller coaxiality is 0.02mm and the surface is burr-free, ensuring the accuracy and uniformity of the printed structure. Printing process: Load the aluminum foil roll onto the unwinding shaft of the printing machine, pass it through the printing rollers, and fix it to the take-up shaft; press the printing rollers tightly and apply a pressure of 2 to 10 tons (a pressure below 2 tons will not form an effective printing structure, and a pressure above 10 tons will cause the aluminum foil to break); apply a tension of 5 to 20 N to the aluminum foil and unwind it at a speed of 0.5 to 5 m / min to construct a three-dimensional mesh-like micron-level printing structure with a grid spacing of 10 to 100 m and a printing depth of 10 to 30 m on the surface of the aluminum foil.

[0008] Step 2: Constructing the nanostructure framework using magnetron sputtering This step, based on inverted magnetron sputtering and oxidation processes, constructs a phase and phase bismuth oxide nanostructure framework on the surface of micron-scale printed aluminum foil, forming a micron-nano multi-level microstructure carrier, while simultaneously solving the problem of overheating and melting of bismuth target materials during magnetron sputtering.

[0009] Preparation before vacuum coating: Invert the micron-scale array printed aluminum foil with the coating side facing down and fix it in the magnetron sputtering vacuum coating chamber (using a jig to hold it to ensure uniform deposition), close the chamber cover, and start the vacuum system to evacuate to 0.0006~0.001 Pa; Bismuth metal deposition: The heating device is activated to heat the substrate to 30~230℃, and argon gas is introduced into the cavity at a flow rate of 10~90 sccm, maintaining the gas pressure in the cavity at 0.1~0.8 Pa; the power of the bismuth metal target is set to 0.1~0.6kW, and the deposition time is 120~1200s. The thickness of the bismuth metal film is controlled by adjusting the deposition time, and the film thickness directly affects the morphology of the subsequent nanostructures. Oxidation to form nanostructures: The substrate temperature is raised to 280~350℃, and a mixture of oxygen and argon gas is introduced into the cavity. The oxygen flow rate is 10~200% of the argon flow rate, and the gas pressure is maintained at 0.1~0.5 Pa. The temperature is maintained for 2~30 min to oxidize the bismuth metal film. During the oxidation process, the bismuth metal forms a phase and a bismuth oxide nanostructure framework under the control of temperature and gas atmosphere. The morphology of the nanostructure can be controlled by controlling the oxidation time and temperature. Post-processing: After the temperature of the coating chamber naturally decreases to room temperature, nitrogen gas is introduced into the chamber to break the vacuum, the chamber cover is opened, and the micron-scale printed aluminum foil with the nanostructure framework is taken out, thus obtaining a multi-level microstructure carrier.

[0010] In this step, the vacuum environment and precise temperature and gas flow control of magnetron sputtering solve the problem that traditional magnetron sputtering methods are difficult to construct nanostructures. At the same time, by using the inverted fixation method of aluminum foil, combined with the water cooling system of the magnetron sputtering equipment, the overheating and melting deformation of the bismuth target is avoided, ensuring the stability of the deposition and oxidation processes.

[0011] Step 3: Magnetron sputtering to support cathode / anode catalyst This step uses magnetron sputtering to load cathode and anodic catalysts onto the surface of a multi-level microstructure support. Compared with the traditional coating method, magnetron sputtering can achieve uniform loading of catalysts, enhance the bonding strength between the catalyst and the nanostructure framework, avoid catalyst agglomeration, and improve the utilization rate of precious metals.

[0012] Cathode catalyst support (platinum-based as an example): a) Fix the multi-level microstructure carrier in the magnetron sputtering vacuum coating chamber, close the chamber cover, evacuate to 0.0006~0.001Pa, heat to 30~200℃, and apply a bias voltage of 0~200V; b) Introduce argon gas into the cavity at a flow rate of 10~90 sccm, maintain a gas pressure of 0.1~0.8 Pa, set the platinum target power to 0.2~0.8 kW, and deposit for 60~360 s. Control the loading of platinum catalyst by adjusting the deposition time. c) After cooling to room temperature, nitrogen gas is introduced to break the vacuum, and the multi-level microstructure support for the platinum catalyst is removed.

[0013] Anode catalyst support (iridium-based as an example): a) Consistent with the pretreatment process for cathode catalyst loading, the multi-level microstructure carrier is fixed, vacuumed, heated, and biased. b) Introduce argon gas and maintain the gas pressure, set the iridium target power to 0.2~0.8kW, and deposit for 90~500s. Control the loading of iridium catalyst by adjusting the deposition time; c) After cooling and breaking the vacuum, the multi-level microstructure support loaded with iridium catalyst is removed.

[0014] In this step, the catalyst can also be a non-precious metal catalyst such as nickel-based or molybdenum-based catalyst, or a ruthenium-iridium alloy catalyst. When loading, the corresponding metal target, oxide ceramic target, nitride ceramic target or sulfide ceramic target can be selected according to the type of catalyst, and DC magnetron sputtering or radio frequency magnetron sputtering process can be used to adapt to the loading requirements of different catalysts.

[0015] Step 4: Fabrication of multi-level microstructured film electrodes by hot pressing transfer This step combines the multi-level microstructured support for the catalyst with the proton exchange membrane using a hot-press transfer process. After peeling off the aluminum foil, a complete membrane electrode is formed, achieving a high-strength bond between the multi-level microstructured support and the proton exchange membrane.

[0016] Preparation for stacking: Stack the multi-level microstructured support for platinum catalyst, the Nafion series proton exchange membrane (N117, N115, N212, etc.), and the multi-level microstructured support for iridium catalyst in sequence, with the catalyst surface in close contact with the proton exchange membrane, and aligned with the edge of the catalyst layer as a reference; control the stacking environment at a temperature of 20~25℃ and a humidity of 20~30% to avoid the influence of ambient temperature and humidity on the bonding effect. Hot pressing process: The stacked components are placed in a roller press, and the hot pressing temperature is set to 90~180℃, the pressure is 4~10T (too high pressure will cause the nanostructure to collapse, and too low pressure will result in poor transfer effect), and the roller pressing speed is 0.1~0.5m / min to carry out hot pressing composite. Peeling and finished product: After hot pressing, the aluminum foil substrate is peeled off from the multi-level microstructure carrier at room temperature using a non-force peeling method. During the peeling process, the nanostructure framework will not fall off the surface of the proton exchange membrane, and finally a multi-level microstructure PEM water electrolysis hydrogen production membrane electrode loaded with cathode and anode catalysts is obtained. Performance testing: The prepared membrane electrode was installed in a PEM electrolyzer, and pure water was used as the electrolyte. The hydrogen production performance was tested under the conditions of test temperature 40~80℃, atmospheric pressure on the anode side and pressure 0~0.4Mpa on the cathode side.

[0017] The technical solution of the present invention has the following advantages over the prior art: The present invention discloses a method for preparing a multi-level microstructured PEM electrolysis water-to-hydrogen membrane electrode. This method innovatively combines a micron-level mesh-like three-dimensional printing structure with a bismuth oxide nanostructure framework to form a multi-level microstructured support, significantly increasing the specific surface area of ​​the membrane electrode to 1.5 to 2 times that of traditional single-layer ordered nanostructured membrane electrodes, thus exposing more catalytic active sites. The catalyst is loaded using magnetron sputtering, achieving uniform catalyst deposition and high bonding strength with the support, resulting in a catalyst utilization rate exceeding 95%, effectively reducing the amount of precious metals used and preventing catalyst agglomeration and detachment. A hot-press transfer process achieves a high-strength bond between the support and the proton exchange membrane, resulting in a membrane electrode with a voltage as low as 1 A / cm at a current density of 1 A. With a voltage range of 6~1.8V, this technology reduces the voltage by 20~60mV compared to traditional membrane electrodes, significantly lowering energy consumption. Furthermore, it maintains excellent stability and durability, achieving a hydrogen purity of 6N after 6000 hours of continuous operation without significant voltage increase. It also incorporates inverted magnetron sputtering and bismuth target cooling technology, overcoming the technical bottlenecks of overheating and melting deformation of low-melting-point bismuth targets during magnetron sputtering, the difficulty in constructing nanostructures using traditional magnetron sputtering, and the limited specific surface area improvement in chemical coating methods. Moreover, the process is implemented using conventional equipment, eliminating the need for customized specialized equipment. The parameters are controllable and highly repeatable, and the raw materials are of industrially common types, demonstrating extremely high feasibility for industrial mass production. This provides core support for the industrialization and promotion of PEM water electrolysis hydrogen production technology. Attached Figure Description

[0018] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 A schematic diagram of the cross-section of a micron-scale printed aluminum foil with a nanostructure framework.

[0019] Figure labeling: 1-Micron-scale printed aluminum foil; 2-Bismuth oxide nanostructure framework. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] The present invention will be further described in detail below with reference to the accompanying drawings.

[0022] A method for preparing a multi-level microstructured PEM water electrolysis hydrogen production membrane electrode includes the following steps: S1. Prepare a micron-scale array printing metal substrate and construct a three-dimensional mesh-like micron-scale printing structure on the surface of the metal substrate; S2. Bismuth metal is deposited and oxidized on the surface of the micron-scale array printed metal substrate by physical vapor deposition to form a metal oxide nanostructure framework, thus obtaining a multi-level microstructure carrier. S3. The cathode catalyst and the anode catalyst are loaded onto the surface of the multi-level microstructure carrier by physical vapor deposition. S4. The multi-level microstructured support for cathode catalyst, the proton exchange membrane, and the multi-level microstructured support for anode catalyst are sequentially stacked and hot-pressed, and the metal substrate is peeled off to obtain the multi-level microstructured PEM water electrolysis hydrogen production membrane electrode.

[0023] It should be noted that this invention constructs a multi-level microstructure membrane electrode through a four-step core process. First, a metal substrate containing a three-dimensional mesh-like micron-scale printed structure is prepared to provide macroscopic support for the carrier. Then, bismuth metal is deposited on the substrate surface using physical vapor deposition and oxidized to form a nanostructure framework, constructing a micron-nano multi-level microstructure carrier. Next, cathode and anodic catalysts are loaded onto both sides of the carrier using physical vapor deposition, ensuring a uniform distribution of catalytic active sites. Finally, the multi-level microstructure carrier loaded with catalysts is composited with a proton exchange membrane via hot pressing transfer, and the finished membrane electrode is obtained after peeling off the metal substrate. The entire process, through multi-scale structural integration and precise process control, achieves improved membrane electrode performance.

[0024] This invention innovatively combines micron-scale macrostructures with nano-scale microstructures, breaking through the bottleneck of increasing the specific surface area of ​​traditional single-scale supports. By combining physical vapor deposition with hot-press transfer technology, it not only solves the problems of catalyst agglomeration and shedding, but also achieves a high-strength bond between the support and the proton exchange membrane. The process route is simple and unified, with strong compatibility, providing a basis for subsequent parameter optimization and material replacement. It is both innovative and practical, and can significantly improve the catalytic performance and stability of membrane electrodes while reducing energy consumption.

[0025] In some embodiments, in step S1, the metal substrate is pure aluminum foil, with a material grade of 1070, 1060, 1100 or 1235 series, and the aluminum foil thickness is 15~50 μm; the grid spacing of the three-dimensional mesh micron-level printing structure is 10~100 μm, and the printing depth is 10~30 μm.

[0026] It should be noted that the metal substrate is limited to pure aluminum foil of the 1070, 1060, 1100 or 1235 series. This type of aluminum foil has suitable plasticity, ductility and peelability. The thickness of 15~50 μm can balance the structural support strength and the ease of subsequent peeling. The grid spacing of the micron-level mesh printing structure is specified to be 10~100 μm and the printing depth is 10~30 μm. This parameter range can ensure the structural integrity, while providing sufficient adhesion space for the nanostructure skeleton, avoiding mass transfer obstruction caused by excessive density or insufficient specific surface area caused by excessive sparseness.

[0027] This invention ensures the molding quality and stability of micron-level printed structures by specifying the substrate material grade and structural parameters, avoiding problems such as printing cracking and peeling difficulties caused by unsuitable substrate materials; the precise structural parameter limitation makes the specific surface area of ​​multi-level microstructures controllable, providing a guarantee for the consistency of membrane electrode performance and reducing the risk of process fluctuations in industrial production.

[0028] In some embodiments, in step S1, the preparation process of the micron-scale array printing metal substrate is as follows: the metal substrate is loaded into a high-precision printing machine, an alloy steel printing roller with a hard chromium plating is used, a pressure of 2 to 10 tons and a tension of 5 to 20 N are applied, and the roller is unwound and wound at a speed of 0.5 to 5 m / min for printing. The coaxiality of the roller is 0.02 mm and the surface is free of burrs.

[0029] It should be noted that the use of a high-precision printing machine with alloy steel printing rollers plated with a hard chromium layer, and a roller coaxiality of 0.02mm and a burr-free surface design, ensures the accuracy and uniformity of the printed structure. Through the coordinated control of 2~10 tons of pressure, 5~20N of tension, and 0.5~5m / min of unwinding and winding speed, the aluminum foil is made to form a regular three-dimensional grid structure under uniform force. Effective printing cannot be formed when the pressure is below 2 tons, and the aluminum foil is prone to breakage when the pressure is above 10 tons. This parameter range is the key to ensuring the printing quality.

[0030] This invention refines the printing equipment and process parameters, solving the technical problems of uneven forming and insufficient precision in micron-level printing structures; the standardized equipment requirements and process parameters make the production process highly replicable, which is conducive to industrial mass production; by limiting the parameter boundaries, it avoids waste of raw materials and product performance defects caused by improper operation, thereby improving the production yield.

[0031] In some embodiments, in step S2, the physical vapor deposition method is a magnetron sputtering method, specifically including: a) Fix the micron-scale array printed metal substrate upside down in the magnetron sputtering vacuum coating chamber, evacuate to 0.0006~0.001 Pa, and heat the substrate to 30~230℃; b) Introduce argon gas at a flow rate of 10~90 sccm, maintain a gas pressure of 0.1~0.8 Pa, use a bismuth metal target with a power of 0.1~0.6 kW, and deposit for 120~1200 s; c) Heat the substrate to 280~350℃, introduce a mixture of oxygen and argon gas, with the oxygen flow rate being 10~200% of the argon flow rate, maintain the gas pressure at 0.1~0.5Pa, and hold for 2~30min to complete the oxidation, thereby obtaining the phase and phase bismuth oxide nanostructure framework. d) After cooling to room temperature, nitrogen gas is introduced to break the vacuum and the multi-level microstructure carrier is removed.

[0032] It should be noted that the nanostructure framework is constructed using magnetron sputtering, and the substrate is fixed by inversion to make the deposition more uniform. Vacuuming to 0.0006~0.001 Pa and heating to 30~230℃ can remove impurities on the substrate surface and activate surface activity, providing good conditions for bismuth metal deposition. The bismuth target power and deposition time are controlled under an argon atmosphere to achieve precise preparation of bismuth metal film. Heating to 280~350℃ and introducing a mixture of oxygen and argon gas causes bismuth metal to oxidize and form phase and phase-oxidized bismuth nanostructures. The morphology of the nanostructure is controlled by the gas flow ratio and holding time.

[0033] This invention precisely controls the magnetron sputtering and oxidation process parameters to achieve controllable preparation of nanostructure frameworks, solving the problem that traditional magnetron sputtering methods are difficult to construct nanostructures. The phase and phase bismuth oxide nanostructures have high specific surface area and good catalytic compatibility, providing a high-quality support for subsequent catalyst loading. The refinement of process parameters stabilizes the morphology of the nanostructures, improves the consistency of membrane electrode performance, and avoids overheating and melting deformation of the bismuth target, ensuring the stability of the production process.

[0034] In some embodiments, in step S3, the cathode catalyst is a platinum-based catalyst and the anode catalyst is an iridium-based catalyst; the physical vapor deposition method is magnetron sputtering, and the loading process includes: a) Fix the multi-level microstructure carrier in the magnetron sputtering vacuum coating chamber, evacuate to 0.0006~0.001Pa, heat to 30~200℃, and apply a bias voltage of 0~200V; b) Argon gas is introduced at a flow rate of 10~90 sccm, and the gas pressure is maintained at 0.1~0.8 Pa. The cathode catalyst layer is prepared by depositing platinum target power of 0.2~0.8 kW for 60~360 s, and the anode catalyst layer is prepared by depositing iridium target power of 0.2~0.8 kW for 90~500 s. c) After cooling to room temperature, nitrogen gas is introduced to break the vacuum, and the multi-level microstructure support for the catalyst is removed.

[0035] It should be noted that platinum-based catalysts were chosen as the cathode and iridium-based catalysts as the anode, as both exhibit excellent hydrogen evolution and oxygen evolution catalytic activities, respectively. The catalyst was deposited on the surface of a multi-level microstructure support by magnetron sputtering, and vacuuming, heating, and biasing were applied to enhance the bonding force between the catalyst and the support. By controlling the target power and deposition time, the catalyst loading could be precisely controlled, avoiding the waste of precious metals due to overloading or the insufficient catalytic activity due to underloading.

[0036] This invention employs magnetron sputtering to support catalysts, achieving uniform deposition of the catalyst on the surface of a multi-level microstructured support. The catalyst utilization rate exceeds 95%, significantly reducing the amount of precious metals required. The high bonding strength between the catalyst and the support solves the problems of catalyst agglomeration and detachment in traditional coating methods. The well-defined loading process parameters allow for controllable catalytic active sites, ensuring stable water electrolysis hydrogen production performance of the membrane electrode.

[0037] In some embodiments, the cathode catalyst further includes nickel-based, molybdenum-based, iron-based, copper-based, manganese-based non-precious metal catalysts or their alloys, nitrides, and sulfides; the anode catalyst further includes ruthenium-based catalysts or ruthenium-iridium alloy catalysts; when loaded, corresponding metal targets, oxide ceramic targets, nitride ceramic targets, or sulfide ceramic targets are used, combined with DC magnetron sputtering or radio frequency magnetron sputtering processes.

[0038] It should be noted that suitable target materials (metal targets, oxide ceramic targets, etc.) are selected for different types of catalysts, and DC or radio frequency magnetron sputtering processes are used to ensure that non-precious metal catalysts, alloy catalysts, etc. can be stably loaded on the surface of multi-level microstructure carriers. By adjusting parameters such as target power and deposition time, the physicochemical properties of different catalysts are adapted to ensure that the active sites of the catalyst are fully exposed after loading.

[0039] This invention expands the range of catalysts that can be selected, breaking the limitation of relying solely on precious metal catalysts and reducing the production cost of membrane electrode assemblies. It optimizes the loading process for different catalysts, enabling various catalysts to be well-matched with multi-level microstructure supports, thus improving the versatility of the method. It also makes it possible to customize the performance of membrane electrodes, allowing the selection of appropriate catalyst types based on actual application scenarios.

[0040] In some embodiments, in step S4, the proton exchange membrane is a Nafion series membrane, including models N117, N115, or N212; during stacking, the catalyst surface and the proton exchange membrane are tightly bonded, the stacking environment temperature is 20~25℃ and the humidity is 20~30%, and the alignment is based on the edge of the catalyst layer.

[0041] It should be noted that Nafion series proton exchange membranes (N117, N115, N212, etc.) are selected because these membranes have good proton conductivity and chemical stability, making them suitable for the working environment of water electrolysis for hydrogen production. During the stacking process, the catalyst layer edges are used as a reference for alignment to ensure precise adhesion between the cathode and anode catalyst layers and the proton exchange membrane, avoiding mass transfer obstruction caused by misalignment. Controlling the temperature and humidity of the stacking environment at 20~25℃ and 20~30% can prevent the proton exchange membrane from absorbing moisture or drying out and deforming, ensuring the composite effect.

[0042] This invention solves the problems of loose bonding and misalignment during membrane electrode composite by specifying the proton exchange membrane type and lamination process; the replaceable proton exchange membrane type allows the method to adapt to different performance requirements, improving application flexibility; and the standardized lamination environment requirements ensure the consistency of product quality and avoid performance fluctuations caused by environmental factors.

[0043] In some embodiments, in step S4, the hot pressing process parameters are: hot pressing temperature 90~180℃, pressure 4~10T, and rolling speed 0.1~0.5m / min; when peeling off the metal substrate, a room temperature non-force peeling method is used to avoid the nanostructure skeleton from falling off.

[0044] It should be noted that in the hot pressing process, the synergistic effect of a temperature of 90~180℃, a pressure of 4~10T, and a rolling speed of 0.1~0.5m / min enables the nanostructure framework loaded with catalyst to fuse with the proton exchange membrane at the interface, forming a high-strength bond. Excessive pressure can easily cause the nanostructure to collapse, while too low pressure will result in poor transfer effect. This parameter range can balance the structural integrity and bonding strength. The aluminum foil can be peeled off at room temperature without force, utilizing the difference in interfacial adhesion between the aluminum foil and the nanostructure framework to achieve damage-free peeling.

[0045] This invention optimizes the hot-press transfer and peeling processes to achieve a high-strength bond between the multi-level microstructure carrier and the proton exchange membrane. The voltage of the membrane electrode does not increase significantly after 6000 hours of continuous operation. The peeling process does not cause the nanostructure framework to fall off, ensuring the structural integrity of the membrane electrode. The refinement of process parameters stabilizes the transfer effect, avoids product scrap due to improper operation, and improves production efficiency.

[0046] In some embodiments, the prepared multi-level microstructured PEM water electrolysis hydrogen production membrane electrode has a specific surface area that is 1.5 to 2 times that of the traditional monolayer ordered nanostructured membrane electrode, and its operating voltage is 1.6 to 1.8 V at a current density of 1 A / cm, which is 20 to 60 mV lower than that of the traditional membrane electrode.

[0047] It should be noted that, through the synergistic effect of the micron-nano hierarchical microstructures, the specific surface area of ​​the membrane electrode is 1.5 to 2 times that of traditional monolayer ordered nanostructure membrane electrodes, exposing more catalytic active sites. The high specific surface area reduces the reaction overpotential, lowering the operating voltage at a current density of 1 A / cm to 1.6–1.8 V, a reduction of 20–60 mV compared to traditional membrane electrodes, resulting in a significant reduction in energy consumption. The supporting effect of the hierarchical microstructures enhances the structural stability of the membrane electrode, ensuring the continued performance advantages. Quantifying the key performance indicators of the membrane electrode directly demonstrates the technical advantages of this method. The significant increase in specific surface area and the significant reduction in energy consumption solve the core problems of low efficiency and high energy consumption in existing membrane electrodes. The clear performance indicators provide standards for product quality testing, which is beneficial for quality control in industrial production.

[0048] In some embodiments, the prepared multi-level microstructure PEM water electrolysis hydrogen production membrane electrode has a catalyst utilization rate of 95%, a continuous working time of 6000 hours without significant voltage increase, and a hydrogen production purity of 6N. The electrolyte tested in the PEM electrolyzer is pure water, and the test temperature is 40~80℃, the anode side is at atmospheric pressure, and the cathode side pressure is 0~0.4Mpa.

[0049] It should be noted that the combination of the high specific surface area of ​​the multi-level microstructure carrier and the uniform loading process of magnetron sputtering results in a catalyst utilization rate of 95%. The stable structural design and high-strength interfacial bonding ensure that the membrane electrode can work continuously for 6000 hours without significant voltage increase. In the PEM electrolyzer, pure water is used as the electrolyte. Under specific temperature and pressure conditions, the catalytic activity and stability of the membrane electrode are fully utilized, and the hydrogen production purity reaches 6N.

[0050] This invention clarifies key indicators such as the long-term stability of the membrane electrode, catalyst utilization rate, and hydrogen production purity, meeting the stringent requirements of industrial hydrogen production; the hydrogen production purity reaches 6N, eliminating the need for additional purification steps and reducing hydrogen production costs; the high catalyst utilization rate and good stability extend the service life of the membrane electrode, further reducing the total life cycle cost and enhancing the industrial application value of the method.

[0051] To make the technical solution of the present invention clearer and more specific, the present invention will be further described in detail below with reference to specific embodiments: Example 1 This embodiment prepares a multi-level microstructured PEM water electrolysis hydrogen production membrane electrode, and the specific steps are as follows: Preparation of micron-level array printing aluminum foil: 1060 series pure aluminum foil with a thickness of 20m is selected; a high-precision printing machine is used with alloy steel printing rollers (hard chrome plated, coaxiality 0.015mm), applying 3 tons of pressure and 8N tension, and printing at a speed of 1m / min to construct a three-dimensional grid structure with a grid spacing of 20m and a printing depth of 15m. Nanostructure framework construction: Printed aluminum foil was inverted and fixed in a magnetron sputtering deposition chamber, vacuumed to 0.0008 Pa, and the substrate was heated to 80 °C; argon gas was introduced at 30 sccm, maintaining a pressure of 0.3 Pa, with a bismuth target power of 0.2 kW, and deposition was carried out for 300 s; the temperature was raised to 300 °C, and a mixture of oxygen and argon gas (oxygen flow rate was 50% of argon gas flow rate) was introduced, maintaining a pressure of 0.2 Pa, and holding for 10 min; after cooling to room temperature, nitrogen gas was introduced to break the vacuum, resulting in a multi-level microstructure carrier for the + phase bismuth oxide nanostructure framework; Catalyst support: Cathode: The multi-level microstructure carrier was fixed, evacuated to 0.0008 Pa, heated to 80 °C, and a bias voltage of 50 V was applied; argon gas was applied at 30 sccm and 0.3 Pa, platinum target power was 0.3 kW, and deposition was carried out for 120 s; Anode: Same as pretreatment, iridium target power 0.3kW, deposition 180s; Hot pressing transfer: The support for the platinum catalyst, the N117 proton exchange membrane, and the support for the iridium catalyst are stacked sequentially (22℃, 25% humidity, edge alignment); hot pressing is performed at a roller press temperature of 120℃, a pressure of 6T, and a speed of 0.2m / min; the aluminum foil is peeled off at room temperature to obtain the membrane electrode. Performance testing: The device was loaded into a PEM electrolyzer with pure water electrolyte, tested at 60°C, and with a cathode-side pressure of 0.2 MPa. The voltage was 1.62 V at a current density of 1 A / cm. The specific surface area was 1.8 times that of a traditional membrane electrode, and the catalyst utilization rate was 96%.

[0052] Example 2 This embodiment prepares a multi-level microstructured PEM water electrolysis hydrogen production membrane electrode, and the specific steps are as follows: Preparation of micron-level array printing aluminum foil: 1100 series pure aluminum foil with a thickness of 30m was selected; the printing machine applied 6 tons of pressure and 15N tension, printed at a speed of 2m / min, with a grid spacing of 50m and a printing depth of 20m; Nanostructure framework construction: Vacuum was applied to 0.0006 Pa, and the substrate was heated to 150 °C; argon gas was applied at 60 sccm and 0.5 Pa, with a bismuth target power of 0.4 kW, for deposition for 600 s; the temperature was then increased to 320 °C, with oxygen flow rate at 100% of the argon gas flow rate and a pressure of 0.3 Pa, and held for 15 min; the vacuum was broken by cooling to obtain a multi-level microstructure carrier. Catalyst support: Cathode: Heated to 120℃, biased at 100V, argon gas at 60sccm and pressure at 0.5Pa, platinum target power at 0.5kW, deposition for 200s; Anode: Iridium target power 0.5kW, deposition 250s; Hot pressing transfer: N115 proton exchange membrane, stacking environment 23℃, humidity 28%, hot pressing temperature 150℃, pressure 8T, speed 0.3m / min, peel off aluminum foil to obtain membrane electrode; Performance testing: Test temperature 70℃, cathode side pressure 0.3Mpa, voltage 1.70V at current density of 1A / cm, specific surface area 1.7 times that of traditional membrane electrode, catalyst utilization rate 97%.

[0053] Example 3 This embodiment prepares a multi-level microstructured PEM water electrolysis hydrogen production membrane electrode, and the specific steps are as follows: Preparation of micron-level array printing aluminum foil: 1235 series pure aluminum foil with a thickness of 40m was selected; the printing machine applied 8 tons of pressure and 18N of tension, and printed at a speed of 3m / min with a grid spacing of 80m and a printing depth of 25m. Nanostructure framework construction: Vacuum was applied to 0.001 Pa, and the substrate was heated to 200 °C; argon gas was applied at 80 sccm and 0.7 Pa, with a bismuth target power of 0.5 kW, for 1000 s deposition; the temperature was then increased to 340 °C, with an oxygen flow rate of 150% of that of argon gas and a pressure of 0.4 Pa, and held for 25 min; the vacuum was broken by cooling to obtain a multi-level microstructure carrier. Catalyst support: Cathode: Heated to 180℃, applied 180V bias voltage, argon gas 80sccm, gas pressure 0.7Pa, platinum target power 0.7kW, deposition for 300s; Anode: Iridium target power 0.7kW, deposition 400s; Hot pressing transfer: N212 proton exchange membrane, stacking environment 24℃, humidity 22%, hot pressing temperature 170℃, pressure 9T, speed 0.4m / min, peel off aluminum foil to obtain membrane electrode; Performance testing: Test temperature 75℃, cathode side pressure 0.4Mpa, voltage 1.78V at current density of 1A / cm, specific surface area 1.6 times that of traditional membrane electrode, catalyst utilization rate 95%.

[0054] Industrial Application Prospects Reference Figure 1 The invention comprises a micron-sized printed aluminum foil (1) and a bismuth oxide nanostructure framework (2). The figure clearly demonstrates the three-dimensional support provided by the micron-sized mesh structure to the nanostructure framework. The resulting multi-level microstructure significantly increases the specific surface area of ​​the carrier. The multi-level microstructure PEM water electrolysis hydrogen production membrane electrode prepared by this invention has advantages such as large specific surface area, low energy consumption, good stability, and high catalyst utilization, and can be widely applied in green electricity hydrogen production, industrial hydrogen production, and fuel cell-related hydrogen production. Furthermore, the preparation process of this invention is compatible with conventional industrial equipment, with controllable process parameters and a high yield, enabling large-scale industrial production and providing core technical support for the industrialization and promotion of PEM water electrolysis hydrogen production technology.

[0055] Compared with the prior art, the present invention has the following significant advantages: Multi-level microstructure significantly increases specific surface area: By combining a micron-level mesh-like three-dimensional printed structure with a bismuth oxide nanostructure framework, a micron-nano multi-level microstructure carrier is formed. The specific surface area of ​​the prepared membrane electrode is 1.5 to 2 times that of the traditional monolayer ordered nanostructure membrane electrode, exposing more catalytic active sites. The operating voltage is as low as 1.6 to 1.8 V at a current density of 1 A / cm, which is 20 to 60 mV lower than the voltage of the traditional membrane electrode, significantly reducing the energy consumption of water electrolysis for hydrogen production. Excellent catalyst loading effect: The catalyst is loaded by magnetron sputtering, which achieves uniform deposition of the catalyst on the surface of the multi-level microstructure support. The catalyst utilization rate is 95%, which effectively reduces the amount of precious metal catalyst. At the same time, the bonding strength between the catalyst and the nanostructure framework is high, avoiding the problems of catalyst agglomeration and detachment in the traditional coating method. The membrane electrode exhibits good stability and durability: the hot-press transfer process achieves a high-strength bond between the multi-level microstructure carrier and the proton exchange membrane. The prepared membrane electrode can work continuously for 6000 hours without significant voltage increase, and the hydrogen production purity reaches 6N, meeting the performance requirements of industrial hydrogen production. Overcoming the bottlenecks of traditional process technology: By drawing on inverted magnetron sputtering and bismuth target cooling technology, the problem of overheating and melting deformation of low-melting-point bismuth targets during magnetron sputtering was solved. At the same time, it overcomes the shortcomings of traditional magnetron sputtering methods in constructing nanostructures and chemical coating methods in increasing specific surface area. High feasibility for industrial mass production: The preparation process of this invention is based on conventional equipment (high-precision printing machine, magnetron sputtering vacuum coating machine, roller press), without the need for customized or modified special equipment. Each process parameter is controllable and has good repeatability. Moreover, the raw materials such as aluminum foil, proton exchange membrane, and target material are all industrially common raw materials, which are suitable for large-scale industrial production.

[0056] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing a multi-level microstructured PEM water electrolysis hydrogen production membrane electrode, characterized in that, Includes the following steps: S1. Prepare a micron-scale array printing metal substrate and construct a three-dimensional mesh-like micron-scale printing structure on the surface of the metal substrate; S2. Bismuth metal is deposited and oxidized on the surface of the micron-scale array printed metal substrate by physical vapor deposition to form a metal oxide nanostructure framework, thus obtaining a multi-level microstructure carrier. S3. The cathode catalyst and the anode catalyst are loaded onto the surface of the multi-level microstructure carrier by physical vapor deposition. S4. The multi-level microstructured support for cathode catalyst, the proton exchange membrane, and the multi-level microstructured support for anode catalyst are sequentially stacked and hot-pressed, and the metal substrate is peeled off to obtain the multi-level microstructured PEM water electrolysis hydrogen production membrane electrode.

2. The method for preparing the multi-level microstructure PEM water electrolysis hydrogen production membrane electrode according to claim 1, characterized in that, In step S1, the metal substrate is pure aluminum foil, with a material grade of 1070, 1060, 1100 or 1235 series, and the aluminum foil thickness is 15~50 μm; the grid spacing of the three-dimensional mesh micron-level printing structure is 10~100 μm, and the printing depth is 10~30 μm.

3. The method for preparing the multi-level microstructure PEM water electrolysis hydrogen production membrane electrode according to claim 1, characterized in that, In step S1, the preparation process of the micron-scale array printing metal substrate is as follows: the metal substrate is loaded into a high-precision printing machine, an alloy steel printing roller with a hard chromium plating is used, a pressure of 2 to 10 tons and a tension of 5 to 20 N are applied, and the roller is unwound and rewound at a speed of 0.5 to 5 m / min for printing. The coaxiality of the roller is 0.02 mm and the surface is free of burrs.

4. The method for preparing the multi-level microstructure PEM water electrolysis hydrogen production membrane electrode according to claim 1, characterized in that, In step S2, the physical vapor deposition method is magnetron sputtering, specifically including: a) Fix the micron-scale array printed metal substrate upside down in the magnetron sputtering vacuum coating chamber, evacuate to 0.0006~0.001 Pa, and heat the substrate to 30~230℃; b) Introduce argon gas at a flow rate of 10~90 sccm, maintain a gas pressure of 0.1~0.8 Pa, use a bismuth metal target with a power of 0.1~0.6 kW, and deposit for 120~1200 s; c) Heat the substrate to 280~350℃, introduce a mixture of oxygen and argon gas, with the oxygen flow rate being 10~200% of the argon flow rate, maintain the gas pressure at 0.1~0.5Pa, and hold for 2~30min to complete the oxidation, thereby obtaining the phase and phase bismuth oxide nanostructure framework. d) After cooling to room temperature, nitrogen gas is introduced to break the vacuum and the multi-level microstructure carrier is removed.

5. The method for preparing the multi-level microstructure PEM water electrolysis hydrogen production membrane electrode according to claim 1, characterized in that, In step S3, the cathode catalyst is a platinum-based catalyst, and the anode catalyst is an iridium-based catalyst; the physical vapor deposition method is magnetron sputtering, and the loading process includes: a) Fix the multi-level microstructure carrier in the magnetron sputtering vacuum coating chamber, evacuate to 0.0006~0.001Pa, heat to 30~200℃, and apply a bias voltage of 0~200V; b) Argon gas is introduced at a flow rate of 10~90 sccm, and the gas pressure is maintained at 0.1~0.8 Pa. The cathode catalyst layer is prepared by depositing platinum target power of 0.2~0.8 kW for 60~360 s, and the anode catalyst layer is prepared by depositing iridium target power of 0.2~0.8 kW for 90~500 s. c) After cooling to room temperature, nitrogen gas is introduced to break the vacuum, and the multi-level microstructure support for the catalyst is removed.

6. The method for preparing the multi-level microstructure PEM water electrolysis hydrogen production membrane electrode according to claim 5, characterized in that, The cathode catalyst also includes nickel-based, molybdenum-based, iron-based, copper-based, manganese-based non-precious metal catalysts or their alloys, nitrides, and sulfides. The anode catalyst also includes ruthenium-based catalysts or ruthenium-iridium alloy catalysts. When loaded, corresponding metal targets, oxide ceramic targets, nitride ceramic targets, or sulfide ceramic targets are used, combined with DC magnetron sputtering or radio frequency magnetron sputtering processes.

7. The method for preparing the multi-level microstructured PEM water electrolysis hydrogen production membrane electrode according to claim 1, characterized in that, In step S4, the proton exchange membrane is a Nafion series membrane, including models N117, N115 or N212; during stacking, the catalyst surface and the proton exchange membrane are tightly bonded, the stacking environment temperature is 20~25℃ and the humidity is 20~30%, and the alignment is based on the edge of the catalyst layer.

8. The method for preparing the multi-level microstructure PEM water electrolysis hydrogen production membrane electrode according to claim 1, characterized in that, In step S4, the hot pressing process parameters are: hot pressing temperature 90~180℃, pressure 4~10T, and rolling speed 0.1~0.5m / min; when peeling off the metal substrate, a room temperature, non-force peeling method is used to avoid the nanostructure skeleton from falling off.

9. The method for preparing the multi-level microstructured PEM water electrolysis hydrogen production membrane electrode according to any one of claims 1 to 8, characterized in that, The prepared multi-level microstructured PEM water electrolysis hydrogen production membrane electrode has a specific surface area that is 1.5 to 2 times that of the traditional monolayer ordered nanostructured membrane electrode, and its working voltage is 1.6 to 1.8 V at a current density of 1 A / cm, which is 20 to 60 mV lower than that of the traditional membrane electrode.

10. The method for preparing the multi-level microstructure PEM water electrolysis hydrogen production membrane electrode according to claim 9, characterized in that, The prepared multi-level microstructure PEM water electrolysis hydrogen production membrane electrode has a catalyst utilization rate of 95%, a continuous working time of 6000 hours without significant voltage increase, and a hydrogen production purity of 6N. The electrolyte tested in the PEM electrolyzer is pure water, and the test temperature is 40~80℃, the anode side is at atmospheric pressure, and the cathode side is at 0~0.4Mpa.

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