Catalyst bridged membrane electrode as well as preparation method and application thereof

Abstract

The invention discloses a catalyst bridged membrane electrode and a preparation method and application thereof, the catalyst bridged membrane electrode comprises an ion exchange membrane layer, a gas-liquid diffusion layer and a catalyst layer; the ion exchange membrane layer is provided with a first surface and a second surface which are opposite to each other, the gas-liquid diffusion layer is provided with a through pore structure and is adjacent to the first surface of the ion exchange membrane, and the bridging catalyst layer is distributed in pores of the gas-liquid diffusion layer and grows to the first surface of the ion exchange membrane along the pores. According to the invention, a catalyst bridged zero-gap membrane electrode construction normal form is provided, a catalyst nanostructure forms a three-dimensional interpenetrating network between an ion exchange membrane and a gas-liquid diffusion layer through an in-situ oriented deposition process, and the physical interface limitation of a traditional CCS / CCM process is broken through. According to the technical path, near-zero gap matching of electron / ion transmission channels is achieved, a high-strength composite interface is established through chemical-mechanical synergistic effect, and a brand new solution is provided for developing a high-efficiency and high-stability membrane electrode suitable for an electrolyte with a wide concentration range.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of hydrogen production by electrolysis of water, in particular to a catalyst-bridged membrane electrode and a preparation method and application thereof. BACKGROUND

[0002] As a core equipment for green hydrogen production, the technical breakthrough of an electrolytic tank is directly related to the process of large-scale development of a hydrogen energy industry. A membrane electrode is a core component for energy conversion in the electrolytic tank, and a current mainstream preparation process adopts catalyst-coated substrate (CCS) or catalyst-coated membrane (CCM) technology. The inherent structural defects of the two technologies lead to two technical bottlenecks: firstly, the contact impedance of a solid-liquid-solid interface is too high, and ohmic polarization loss is serious, especially in a low-concentration alkaline electrolyte (less than 0.1M KOH) or a pure water system; and secondly, a pore blocking effect is caused by a binder of an ionomer when a three-phase reaction interface is constructed, leading to a reduction in the utilization rate of active sites, and the mechanical bonding strength between a catalyst layer and an anion exchange membrane and a gas-liquid diffusion layer is not firm, and it is difficult to adapt to frequent start-stop working conditions caused by wind and light power fluctuations. SUMMARY

[0003] The application aims to at least solve one of the technical problems in the prior art. To this end, the application provides a catalyst-bridged membrane electrode and a preparation method and application thereof. The application proposes a catalyst-bridged zero-gap membrane electrode construction paradigm. Through an in-situ directional deposition process, a catalyst nanostructure forms a three-dimensional interpenetrating network between an ion exchange membrane and a gas-liquid diffusion layer, thereby breaking through the physical interface limitation of a traditional CCS / CCM process. The technical path not only realizes near-zero-gap matching of an electron / ion transmission channel, but also establishes a high-strength composite interface through chemical-mechanical synergistic action, thereby providing a new solution for developing a high-efficiency and high-stability membrane electrode suitable for electrolyte in a wide concentration range.

[0004] The application further provides a preparation method of the catalyst-bridged membrane electrode.

[0005] The application further provides application of the catalyst-bridged membrane electrode in the field of water electrolysis.

[0006] According to a first aspect of the application, a catalyst-bridged membrane electrode is provided, comprising an ion exchange membrane layer, a gas-liquid diffusion layer and a catalyst layer;

[0007] The ion exchange membrane layer has opposite first and second surfaces,

[0008] The gas-liquid diffusion layer is provided with a through-pore structure and is arranged adjacent to the first surface of the ion exchange membrane,

[0009] The bridged catalyst layer is distributed inside the pores of the gas-liquid diffusion layer and grows along the pores to the first surface of the ion exchange membrane.

[0010] The functions of the gas-liquid diffusion layer in the present application mainly include: (1) efficient transport of gas; (2) management and supply of aqueous solution, especially the timely replenishment of aqueous solution to the catalyst surface under high current density, and the prevention of anion exchange membrane from drying and failure due to lack of water; (3) serving as a conductive channel between the bipolar plate and the catalyst layer, the selection of a metal material with high electrical conductivity and porosity as the gas-liquid diffusion layer will help to uniformly distribute the current density; (4) serving as a mechanical support, the gas-liquid diffusion layer is generally made of rigid materials, which provides support for the flexible anion exchange membrane. In particular, the construction of the zero-gap membrane electrode in this work requires a rigid gas-liquid diffusion layer skeleton to provide support for the in-situ grown catalyst layer. The ion exchange membrane selectively conducts OH- or H + Ions maintain electrolytic charge balance and effectively block the mixing of hydrogen and oxygen, ensuring product purity and system safety. The innovative design of the catalyst bridging layer not only realizes the zero-gap tight contact between the gas-liquid diffusion layer and the ion exchange membrane, significantly reducing the interface resistance, but also greatly improves the interface bonding strength through the chemical-mechanical synergistic effect, making the entire membrane electrode structure exhibit excellent mechanical stability under fluctuating conditions. This multi-component synergistic design collectively builds a high-performance, high-stability electrolytic water hydrogen production system.

[0011] According to the first aspect of the present application, at least the following beneficial effects are achieved:

[0012] (1) Significantly reduce the interface resistance: the present application realizes the close contact between the catalyst and the ion exchange membrane through the structure design of the catalyst bridging layer, which significantly reduces the interface resistance compared to the traditional CCS method and CCM method membrane electrode preparation technology, thereby greatly reducing the requirement for electrolyte concentration, and significantly widening the application range of electrolyte.

[0013] (2) Excellent stability: the catalyst-bridged membrane electrode of the present application has ultra-long cycle operation stability when applied to actual energy conversion devices, and the structure is well adapted to renewable energy, which can be applied to actual complex fluctuating energy electrolysis scenarios, and can withstand fluctuating current impact caused by renewable energy fluctuations. The interface bonding force does not significantly decay during long-term operation, ensuring long-term stable operation of the system.

[0014] (3) Simplify the structure and improve the efficiency: the present application does not need to use the ionomer binder required in the traditional method, simplifies the membrane electrode structure, effectively shortens the ion transport path in the electrolysis process, and improves the utilization rate of active sites, thereby achieving an energy conversion efficiency of up to 85.7%, reaching the industry-leading level.

[0015] (4) Good universality and application prospect: the catalyst bridging of the application has good universality and is suitable for various electrocatalytic materials and water electrolysis devices, especially in low-concentration alkaline electrolyte or pure water electrolysis, which exhibits extremely broad application potential and provides an efficient and reliable technical path for the large-scale preparation of green hydrogen.

[0016] According to some embodiments of the application, the preparation raw material of the catalyst bridging layer comprises at least one of a metal element, a metal alloy, a metal oxide and a metal hydroxide.

[0017] The preparation raw material of the catalyst bridging layer can provide rich active site selection to meet the needs of different electrolysis environments and optimize the catalytic performance.

[0018] According to some embodiments of the application, the metal comprises at least one of Ni, Fe, Co, Mo and Cr.

[0019] According to some embodiments of the application, the preparation raw material of the gas-liquid diffusion layer comprises at least one of foamed nickel, foamed cobalt, foamed copper, nickel mesh, titanium mesh, stainless steel felt and carbon paper.

[0020] The above-mentioned materials not only have high electrical conductivity (to ensure uniform distribution of current), but also realize efficient gas transmission and rapid electrolyte diffusion due to their three-dimensional porous structure. At the same time, they have mechanical strength and chemical stability, which can provide an ideal substrate for catalyst bridging growth.

[0021] According to some embodiments of the application, the ion exchange membrane comprises at least one of a proton exchange membrane and an anion exchange membrane.

[0022] According to some embodiments of the application, the proton exchange membrane comprises at least one of a perfluorosulfonic acid type proton exchange membrane, a sulfonated polyether ether ketone type proton exchange membrane and a benzimidazole type proton exchange membrane.

[0023] According to some embodiments of the application, the anion exchange membrane comprises at least one of a polyaryl piperidine type anion membrane, a polysulfone type anion exchange membrane, a quaternary ammonium salt type anion membrane, an imidazole salt type anion membrane and a block copolymer type anion membrane.

[0024] According to the second aspect of the application, a preparation method of a catalyst-bridged membrane electrode is provided, comprising the following steps: fixing the ion exchange membrane and the gas-liquid diffusion layer in an electrodeposition device, adding an electrodeposition conductive liquid containing metal ions of the catalyst bridging layer to the electrodeposition device, and then performing electrodeposition treatment to obtain the catalyst-bridged membrane electrode.

[0025] According to the second aspect of the application, at least the following beneficial effects are achieved:

[0026] Metal ions will produce directional movement under the action of electric field, and combine with the ions in the surrounding chemical environment to produce new material structure. The application forms a three-dimensional interpenetrating network between the ion exchange membrane and the gas-liquid diffusion layer through the electrodeposition process. First, the gas-liquid diffusion layer and the ion exchange membrane are fixed at a specific position to ensure the stability of the relative position of the two; second, the metal ions in the electrodeposition conductive liquid are directionally grown in the ordered structure of the gas-liquid diffusion layer to form a bridging structure, so that the catalyst layer and the ion exchange membrane are closely attached; finally, by controlling the electrodeposition conditions (such as current density and time), the microstructure of the catalyst layer is optimized to achieve the best electrochemical performance.

[0027] According to some embodiments of the application, the preparation raw materials of the electrodeposition conductive liquid include at least one of chlorides, sulfates, sulfites, nitrates, nitrites, molybdates and phosphates containing catalyst metal elements.

[0028] According to some embodiments of the application, the preparation raw materials of the electrodeposition conductive liquid further include an additive, and the additive includes at least one of inorganic salts, inorganic bases, inorganic acids and organic alcohols.

[0029] According to some embodiments of the application, the inorganic salts include at least one of sodium chloride, potassium chloride, sodium sulfate, sodium nitrate and potassium nitrate.

[0030] According to some embodiments of the application, the inorganic bases include at least one of alkaline sodium hydroxide and potassium hydroxide.

[0031] According to some embodiments of the application, the inorganic acids include at least one of hydrogen chloride, sulfuric acid and nitric acid.

[0032] According to some embodiments of the application, the organic alcohols include at least one of ethanol, isopropyl alcohol and ethylene glycol.

[0033] According to some embodiments of the application, the metal elements include at least one of nickel, iron, cobalt, molybdenum and chromium.

[0034] According to some embodiments of the application, in the electrodeposition conductive liquid, the concentration of metal ions is 0.1-1 mol / L; and the pH of the electrodeposition liquid is 5-7.

[0035] Under the above conditions, sufficient supply of metal ions is ensured, so that the catalyst can be uniformly deposited, and the problems of uneven deposition or dendrite growth caused by too high concentration are avoided. At the same time, the near-neutral pH environment not only protects the ion exchange membrane from corrosion by strong acid and strong base, prolonging the service life of the membrane electrode, but also maintains the stable state of the metal ions, ensuring the deposition of the catalyst in a high-activity crystal form.

[0036] According to some embodiments of the present application, the parameters of the electrodeposition treatment step include: the electrodeposition current density is 10-200 mA / cm 2 ; the electrodeposition time is 10-3600 s.

[0037] Under the above conditions, the precise control of the catalyst bridging layer structure is achieved, and the optimized current density range ensures the sufficient deposition reaction and avoids the damage to the deposition layer caused by the hydrogen evolution at high current density, thereby ensuring the dense and uniform deposition layer.

[0038] According to some embodiments of the present application, the temperature of the electrodeposition is 0-80℃.

[0039] According to a third aspect of the present application, the application of the catalyst-bridged membrane electrode in the field of water electrolysis is proposed.

[0040] The catalyst-bridged zero-gap membrane electrode disclosed in the present application has the characteristics of low interfacial resistance, strong interfacial bonding force and no ionomer bonding, and compared with the traditional CCS method and CCM method membrane electrode preparation technology, the excellent performance of only 1.80V at 2.00A cm-2 in 1M KOH electrolyte and only 1.87V at 2.00A cm-2 in pure water electrolysis can be achieved. At 1.00A cm-2, the energy conversion efficiency is 85.7%, which is at a leading level.

[0041] According to some embodiments of the present application, the field of water electrolysis includes the field of water electrolysis in a wide concentration range.

[0042] The catalyst-bridged membrane electrode of the present application is suitable for electrolytic environments with different conductivities, has the advantages of low interfacial resistance and high active site utilization rate, and thus can still maintain excellent energy conversion efficiency in low-concentration alkaline electrolyte and pure water electrolyte; for alkaline electrolyte, the membrane electrode is suitable for a range of hydroxyl ion (OH-) concentrations of 0.01-6 mol / L; for pure water electrolysis, the membrane electrode is suitable for an ultra-low conductivity system with an ionic conductivity of less than 1 μS / cm.

[0043] According to some embodiments of the present application, the water electrolysis process is realized by an electrolysis system, the electrolysis system includes a water electrolysis hydrogen production device, the hydrogen production device includes a cathode inlet, a cathode outlet, an anode inlet and an anode outlet, a membrane electrode and conductive end plates arranged on both sides, the end plates are internally provided with gas-liquid flow channels; the conductive end plates are selected from at least one of a metal nickel plate, a stainless steel plate or a titanium plate.

[0044] According to some embodiments of the present application, the membrane electrode of the water electrolysis hydrogen production device includes a gas-liquid diffusion layer, an anion exchange membrane and a catalyst.

[0045] According to some embodiments of the present application, the catalyst comprises at least one of Ni metal, NiCo, NiFe, Co metal, or CoFe.

[0046] According to some embodiments of the present application, the electrolysis system comprises a renewable energy driving device, which comprises photovoltaic power generation or wind power generation.

[0047] The novel zero-gap membrane electrode structure described above has extremely low interface resistance and strong interface bonding force, and is free from the dependence on ionomer binder in the traditional membrane electrode production process, has good adaptability to renewable energy, and has good application prospect.

[0048] Unless otherwise specified, "about" in the present application actually means that the allowed error is within ±2%, for example, about 100 actually means 100 ± 2% x 100.

[0049] Unless otherwise specified, "between" in the present application includes the numbers, for example, "between 2-3" includes the end point values 2 and 3.

[0050] Other features and advantages of the present application will be set forth in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following or can be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0051] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the description of the embodiments, taken in conjunction with the following drawings in which:

[0052] Figure 1 Schematic diagram of the zero-gap membrane electrode structure bridged by the catalyst of the present application;

[0053] Figure 2 Performance diagram of the novel membrane electrode structure in application example 1 of the present application for AEM alkaline water electrolysis device;

[0054] Figure 3 Performance diagram of the novel membrane electrode structure in application example 2 of the present application for AEM pure water electrolysis device;

[0055] Figure 4 Long-period stability test diagram of the novel membrane electrode structure in test example 1 of the present application for AEM pure water electrolysis device;

[0056] Figure 5 Green fluctuation energy working condition electrolysis performance diagram of the novel membrane electrode structure in test example 2 of the present application for AEM pure water electrolysis device;

[0057] Figure 6 Practicality comparison diagram of the novel membrane electrode structure in test example 3 of the present application for application to various catalytic materials and various anion exchange membranes;

[0058] Figure 7 This is a comparison diagram of the contact resistance of the novel membrane electrode and the conventional membrane electrode fabrication method in Test Example 4 of this invention;

[0059] Figure 8 This is a comparison of the electrochemically active surface area of ​​the novel membrane electrode and the conventional membrane electrode prepared by the test example 5 of this invention;

[0060] Figure 9 This is a comparison diagram of the interfacial bonding force between the novel membrane electrode and the traditional membrane electrode preparation method in Test Example 6 of this invention. Detailed Implementation

[0061] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0062] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0063] Example 1

[0064] This embodiment discloses a method for preparing a catalyst-bridged membrane electrode (catalyst-bridged zero-gap membrane electrode), the preparation process of which is as follows:

[0065] Preparation of electrodeposition conductive solution: An electrolyte synthesis catalyst (NiFe) was prepared using Fe(NO3)3·9H2O (8.08 g, 99.99%) and Ni(NO3)2·6H2O (5.80 g, AR, 98%). This was achieved by dissolving Ni(NO3)2·6H2O, Fe(NO3)3·9H2O, KNO3 (10.10 g, ACS, ≥99.0%), and C6H5Na3O7 (15.48 g, 98%) in deionized water, and obtaining 200 mL of a conductive solution containing 100 mM Fe in the anode bath. 3+ 100mM Ni 2+ 1000mM NO3 - and 900mM Na +A solution of KOH was obtained by dissolving KOH in 200 mL of deionized water in a cathode tank, yielding a 1000 mM KOH solution. - The solution.

[0066] Zero-gap membrane electrode construction: Nickel foam and cobalt foam were selected as gas-liquid diffusion layers. Nickel foam, anion exchange membrane (AEM, using Sustainion X37-50 grade RT membrane), and cobalt foam were respectively loaded into anion exchange membrane electrolyzer (AEMWE). The connectors of the working electrode and sensing electrode were connected to the anode, and the connectors of the reference electrode and counter electrode were connected to the cathode. The electrolytes in the anode and cathode tanks were added to the AEMWE from the anode side and cathode side, respectively, at a flow rate controlled at 1 mL / min. -1， Apply -50mA cm to AEMWE -2 The current density was applied for 30 minutes, followed by cleaning with deionized water at a flow rate of 1 mL / min. -1， Finally, both the anode and cathode cells were added to the 1M KOH electrolyte, and a 200mA cm⁻¹ pressure was applied to AEMWE. -2 A current density of 120 min was used to activate the anode catalyst, resulting in a catalyst-bridged zero-gap membrane electrode, as shown in the schematic diagram. Figure 1 As shown.

[0067] Example 2

[0068] This embodiment discloses a method for preparing a catalyst-bridged membrane electrode (catalyst-bridged zero-gap membrane electrode), the preparation process of which is as follows:

[0069] This embodiment discloses a method for constructing a zero-gap membrane electrode bridged by an Fe-Co based catalyst. The difference between this embodiment and Example 1 lies in the specific preparation process of the Fe-Co catalyst system, which is as follows:

[0070] Preparation of electrodeposition conductive solution: Fe(NO3)3·9H2O (8.08 g, 99.99%) and Co(NO3)2·6H2O (5.82 g, AR, 98%) were weighed as precursors and dissolved together with KNO3 (10.10 g, ACS≥99.0%) and sodium citrate (C6H5Na3O7, 15.48 g, 98%) in 200 mL of deionized water to prepare the anolyte containing 100 mM Fe. 3+ 100mM Co 2+ 1000mM NO3 - and 900mM Na + The cathode electrolyte is 200 mL containing 1000 mM OH. - KOH solution.

[0071] Catalyst-bridged membrane electrode: (1) Cobalt foam (12mm×12mm×0.5mm) was selected as the gas-liquid diffusion layer and assembled with Sustainion X37-50 anion exchange membrane in an AEM electrolyzer; (2) The anolyte was circulated at a flow rate of 1mL / min and -50mA / cm was applied. 2 (2) Pre-deposition at a current density of 30 minutes; (3) After rinsing with deionized water, use 1M KOH electrolyte at 200mA / cm 2 Deposition was carried out at the current density for 120 minutes; (4) Fe-Co hydroxide-bridged membrane electrode was finally obtained.

[0072] Example 3

[0073] This embodiment discloses a method for preparing a catalyst-bridged membrane electrode (catalyst-bridged zero-gap membrane electrode). The difference between this embodiment and Example 1 lies in the catalyst (Ni-Co catalyst system). The specific preparation process is as follows:

[0074] Preparation of electrodeposition conductive solution: An electrolyte synthesis catalyst (NiCo) was prepared using Ni(NO3)2·6H2O (5.80 g, AR, 98%), Co(NO3)2·6H2O (5.82 g), and NaNO3 (8.50 g). This was achieved by dissolving Ni(NO3)2·6H2O (5.80 g, AR, 98%), Co(NO3)2·6H2O (5.82 g), and NaNO3 in deionized water, and obtaining 200 mL of a conductive solution containing 100 mM Co in the anode bath. 2+ 100mM Ni 2+ 1000mM NO3 - and 900mM Na + A solution of KOH was obtained by dissolving KOH in 200 mL of deionized water in a cathode tank, yielding a 1000 mM KOH solution. - The solution.

[0075] Zero-gap membrane electrode construction: Nickel foam and cobalt foam were selected as gas-liquid diffusion layers. Nickel foam, anion exchange membrane (AEM, using Sustainion X37-50 grade RT membrane), and cobalt foam were respectively loaded into anion exchange membrane electrolyzer (AEMWE). The connectors of the working electrode and sensing electrode were connected to the anode, and the connectors of the reference electrode and counter electrode were connected to the cathode. The electrolytes in the anode and cathode tanks were added to the AEMWE from the anode side and cathode side, respectively, at a flow rate controlled at 1 mL / min. -1， Apply -50mA cm to AEMWE -2 The current density was applied for 30 minutes, followed by cleaning with deionized water at a flow rate of 1 mL / min. -1，Finally, both the anode and cathode cells were added to the 1M KOH electrolyte, and a 200mA cm⁻¹ pressure was applied to AEMWE. -2 A current density of 120 min was used to activate the anode catalyst, resulting in a catalyst-bridged zero-gap membrane electrode.

[0076] Example 4

[0077] This embodiment discloses a catalyst-bridged membrane electrode. The difference between this embodiment and Embodiment 1 is that (the catalyst is a Fe single-metal catalyst system), while the other conditions are the same.

[0078] Comparative Example 1

[0079] This comparative example discloses a method for preparing a catalyst-bridged zero-gap membrane electrode, the preparation process of which is as follows:

[0080] Preparation of NiFe catalyst ink: NiFe catalyst (50 mg) was dispersed in deionized water (5.88 mL), anhydrous 2-propanol (4 mL), and PiperION-A5-HCO3-EtOH-5 wt% (0.12 mL), and the suspension was sonicated until a uniform ink was obtained.

[0081] Traditional CCS membrane electrode assembly (CCS-MEA) fabrication: The AEM membrane used was a Sustainability X37-50 grade RT membrane. The cathode material diffusion layer (GDL) was nickel foam (12mm × 12mm × 0.5mm), and the anode GDL was cobalt foam (12mm × 12mm × 0.5mm). Catalyst ink was uniformly sprayed onto the Co foam (5mg cm⁻²). The treated cobalt foam, AEM, and nickel foam were loaded into the AEMWE. Both the anode and cathode tanks were added to 1M KOH as electrolytes. A current of 200mA was applied to the AEMWE for 120 minutes to activate the anode catalyst.

[0082] Conventional CCM membrane electrode assembly (CCM-MEA) fabrication: The AEM membrane used was a Sustainability X37-50 grade RT membrane. The cathode GDL was nickel foam (12mm × 12mm × 0.5mm), and the anode GDL was cobalt foam (12mm × 12mm × 0.5mm). Catalyst ink was uniformly sprayed onto the AEM (5mg cm⁻²). The cobalt foam, treated AEM, and nickel foam were then loaded into the AEMWE. Both the anode and cathode tanks were added to 1M KOH as electrolytes. A current of 200mA was applied to the AEMWE for 120 minutes to activate the anode catalyst.

[0083] Application Example 1

[0084] This test example discloses the application of the catalyst-bridged zero-gap membrane electrode prepared in the examples to an alkaline water electrolysis hydrogen production device, specifically:

[0085] AEMWE Assembly and Electrochemical Measurements: Based on the preparation of MEA in Example 1, Pt / C (1 mg cm⁻¹) was used to assemble and measure the electrochemical properties of the MEA. -2 A catalyst is added to the cathode to assemble AEMWE. Both the cathode and anode end plates of the electrolyzer are made of nickel-plated stainless steel, and serpentine flow channels are etched on both end plates to allow electrolyte circulation. A peristaltic pump is used around the electrolyzer to draw electrolyte from the storage tank and pump it into the electrolyzer. The outlet pipe of the electrolyzer is connected to the storage tank, forming an electrolyte circulation system.

[0086] Both the cathode and anode plates of the electrolytic cell were electrically connected to the electrochemical workstation via tabs. The performance of AEMWE in 1M KOH was investigated using the electrochemical workstation (Zahner XC, Germany) at 20℃ and 60℃, with the electrolyte flow rate controlled at 1 mL / min. -1 Use a heater to regulate the temperature. At 5mV / s -1 Linear scan voltammetry (LSV) curves were obtained at a scan rate of 1.8 V or 100 mA cm⁻¹. -2 Electrochemical impedance spectroscopy (EIS) was performed at current densities ranging from 100 kHz to 0.1 Hz.

[0087] Figure 2 This demonstrates the application of a catalyst-bridged zero-gap membrane electrode (ZG-NiFe) in a 1M KOH electrolyte in an anion exchange membrane electrolyzer (AEMWE). Figure 2 As can be seen from the LSV curve in a, the zero-gap film electrode of Example 1 achieved 1.8V and 1A cm⁻¹ at 60°C. -2 At room temperature (20℃), 1.92V, 1A cm -2 Its superior electrolysis performance surpasses that of electrolysis devices achieved using the same catalyst via CCS and CCM membrane electrode preparation technologies. Figure 2 The EIS curves in section b show the electrochemical impedance curves of electrolytic devices assembled with different membrane electrodes. It can be seen that the zero-gap membrane electrode method has the lowest resistance at both room temperature and 60°C.

[0088] Application Example 2

[0089] This test example discloses a catalyst-bridged zero-gap membrane electrode applied to a pure water electrolysis hydrogen production device. The membrane electrode construction method and the assembly and testing method of the anion exchange membrane electrolysis device are the same as those in Application Example 1. The difference from Application Example 1 is that pure water is used as the electrolyte. The application performance of the catalyst-bridged zero-gap membrane electrode prepared in Example 1 is tested in an extremely low concentration electrolyte (pure water).

[0090] Figure 3 Figure 'a' shows the performance of the same catalyst applied to a pure water AEM electrolysis device under different membrane electrode preparation methods. Achieving a current density of 2 A cm⁻² requires only 1.87 V at 60 °C and only 1.95 V at room temperature (20 °C). Figure 3 Figure b shows the electrochemical impedance spectroscopy curves of different membrane electrode preparation methods applied to pure water. The results show that the catalyst-bridged zero-gap membrane electrode disclosed in Example 1 has significantly better performance than other membrane electrode preparation techniques.

[0091] Test Example 1

[0092] This embodiment discloses a catalyst-bridged zero-gap membrane electrode applied to a long-term stability test of pure water electrolysis to illustrate the long-term stability of the catalyst-bridged membrane electrode of the present invention. The construction method of the catalyst-bridged zero-gap membrane electrode and the assembly method of the AEM electrolysis device are the same as those in application example 1 above, the difference being that pure water is used as the electrolyte in this test example, and a constant electrolysis current of 500 mA is set. -2 Conduct long-term electrolysis experiments and record the changes in electrolysis voltage over time.

[0093] Figure 4 This is a graph showing the long-cycle electrolysis stability test record of Test Example 1, from... Figure 4 As can be seen from 'a' in the figure, the AEM device equipped with a zero-gap film electrode operates at 500 mA cm⁻¹. -2 It can maintain long-term stability for 1000 hours at a current density, with a voltage decay rate of 65μV h. -1 It exhibits characteristics of stable operation over a long period of time.

[0094] Test Example 2

[0095] This test example discloses a catalyst-bridged zero-gap membrane electrode used in the electrolysis of pure water under fluctuating energy conditions to illustrate the adaptability of the catalyst-bridged membrane electrode in practical applications. This test example integrates a solar power generation system with a zero-gap membrane electrode AEM electrolysis device supplied by pure water. Figure 5 (a) Continuous outdoor testing was conducted over three days from 9:00 AM to 5:00 PM, recording the changes in voltage and current response of the electrolytic device under different solar intensities over time.

[0096] Figure 5 The results showed that the zero-gap membrane electrode AEM water electrolysis device maintained a stable current and voltage response. Minimal performance degradation was observed by comparing the LSV and EIS curves before and after the outdoor test. Figure 5 b in Figure 5c) indicates that the zero-gap membrane electrode has the ability to adapt to fluctuating energy coupling, showing the industrial application prospects of green hydrogen.

[0097] Finally, the stability of the zero-gap membrane electrode AEM water electrolysis device under fluctuating current density was further evaluated using the Accelerated Stress Testing (AST) procedure. The ZG-AEMWE was tested at 500-200-100-200 mA cm⁻¹. -2 AST was performed within the range of fluctuating current density, with each cycle lasting 20 minutes. Figure 5 As shown in d. After 1300 test cycles, at 500mA cm -2 A decay of 57 mV was observed. Overall, the ZG-AEMWE exhibits a stable response to renewable energy, thus demonstrating promising prospects for industrial applications of green hydrogen.

[0098] Test Example 3

[0099] This test example discloses a method for preparing a zero-gap membrane electrode using catalyst bridging, which is applicable to a variety of catalyst types and has universality.

[0100] The catalyst comprises: NiFe mixed hydroxide (Example 1), FeCo mixed hydroxide (Example 2), NiCo mixed hydroxide (Example 3), and Fe hydroxide (Example 4).

[0101] Anion exchange membranes include: Sustainion X37-50, PiperION A60, FAS-50, and FAA-3-50.

[0102] Figure 6 The performance of zero-gap membrane electrodes assembled with different types of catalysts and different types of anion exchange membranes is demonstrated.

[0103] Test Example 4

[0104] This test example discloses the performance differences in contact resistance between the catalyst-bridged membrane electrode of this invention and membrane electrodes prepared by traditional CCS and CCM methods. Specific experimental method: EIS curves of membrane electrodes prepared by different methods were measured in the device, and the corresponding contact resistance was obtained based on the intersection points of these curves with the horizontal axis in the high-frequency region.

[0105] Figure 7 The figure shows a comparison of the contact resistance of three types of membrane electrodes. As can be seen from the figure, the contact resistances of the membrane electrodes prepared by CCM, CCS and the novel method (ZG) of this patent are 155mΩ, 146mΩ and 98mΩ, respectively, indicating that the novel membrane electrode of this patent has a lower contact resistance than the membrane electrode prepared by the traditional method.

[0106] Test Example 5

[0107] This test example discloses a comparison of the electrochemically active surface area between the novel catalyst-bridged zero-gap membrane electrode of Example 1 of this invention and membrane electrodes prepared by traditional CCS and CCM methods. Specific experimental methods: CV curves of the three MEAs were measured in the non-Radidatic potential range, with voltage scan rates starting from 20 mV / s. -1 Increased to 100mV s -1 The cyclic voltammetry curves obtained from each MEA are combined with the formula (C). dl =i c Linear regression was performed on each of the / v) to obtain the equivalent double-layer capacitance value for each MEA.

[0108] Figure 8 The figure shows a comparison of the electrochemical active surface area properties of the three membrane electrodes. It can be seen from the figure that the equivalent double-layer capacitance of the membrane electrodes prepared by CCM, CCS, and ZG is 2.08 mF / cm². -2 8.45mF cm -2 and 18.24mF cm -2 The equivalent double-layer capacitance is positively correlated with the electrochemically active surface area per unit geometric area, reflecting the number of electrochemically active sites. These results indicate that the novel membrane electrode construction method proposed in this patent has the highest electrochemically active surface area among all membrane electrodes, thus providing abundant active sites.

[0109] Test Example 6

[0110] This test example discloses a comparison of the interfacial bonding strength between the novel catalyst-bridged zero-gap membrane electrode of this patent and the membrane electrode prepared by the traditional CCM method. Specific experimental methods: The membrane electrode assemblies of both methods were disassembled, and the catalyst bonding strength on the surfaces of the two anion exchange membranes was quantitatively analyzed using a micron-level scratch tester combined with an optical microscope. The scratch length was 1 mm, and the normal stress increased linearly from 0 to 2 N. By combining the normal stress-friction force curves and optical microscopic images, the critical normal stress of different samples, i.e., the interfacial bonding strength between the catalyst and the anion exchange membrane, can be analyzed.

[0111] Figure 9 A comparison of the interfacial bonding strength between the anion exchange membrane and the catalyst for membrane electrodes prepared by the two methods shows that the interfacial bonding strength between the anion exchange membrane and the catalyst of the zero-gap membrane electrode is approximately 1.29 N, which is greater than that of the membrane electrode prepared by the CCM method (0.63 N).

[0112] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A catalyst-bridged membrane electrode, characterized in that, It includes an ion exchange membrane layer, a gas-liquid diffusion layer, and a catalyst layer; The ion exchange membrane layer has a first surface and a second surface opposite to each other. The gas-liquid diffusion layer has a through-pore structure and is disposed adjacent to the first surface of the ion exchange membrane. The bridging catalyst layer is distributed inside the pores of the gas-liquid diffusion layer and grows along the pores to the first surface of the ion exchange membrane.

2. The catalyst-bridged membrane electrode according to claim 1, characterized in that, The raw materials for preparing the bridging catalyst layer include at least one of elemental metals, alloys, metal oxides, and metal hydroxides.

3. The catalyst-bridged membrane electrode according to claim 1, characterized in that, The raw materials for preparing the gas-liquid diffusion layer include at least one of nickel foam, cobalt foam, copper foam, nickel mesh, titanium mesh, stainless steel felt, and carbon paper.

4. The catalyst-bridged membrane electrode according to claim 1, characterized in that, The ion exchange membrane includes at least one of a proton exchange membrane and anion exchange membrane.

5. A method for preparing a catalyst-bridged membrane electrode as described in any one of claims 1 to 4, characterized in that, Includes the following steps: The ion exchange membrane and the gas-liquid diffusion layer are fixed in an electrodeposition device. An electrodeposition conductive liquid containing metal ions of the bridging catalyst layer is added to the electrodeposition device, and then an electrodeposition process is performed to obtain the catalyst-bridged membrane electrode.

6. The method for preparing the catalyst-bridged membrane electrode according to claim 5, characterized in that, The raw materials for preparing the electrodeposition conductive liquid include at least one of chloride, sulfate, sulfite, nitrate, molybdate, and phosphate containing a catalyst metal element.

7. The method for preparing the catalyst-bridged membrane electrode according to claim 6, characterized in that, The metallic element includes at least one of nickel, iron, cobalt, molybdenum, and chromium.

8. The method for preparing the catalyst-bridged membrane electrode according to claim 5, characterized in that, The concentration of metal ions in the electrodeposition conductive solution is 0.1–1 mol / L; the pH of the electrodeposition conductive solution is 5–7.

9. The method for preparing the catalyst-bridged membrane electrode according to claim 5, characterized in that, The parameters for the electrodeposition process include: an electrodeposition current density of 10–200 mA / cm². 2 The electrodeposition time is 10–3600 s.

10. The application of a catalyst-bridged membrane electrode as described in any one of claims 1 to 4 in the field of water electrolysis.

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