Dynamic self-adaptive seawater electrolysis electrode material and preparation method thereof

Abstract

The invention provides a dynamic self-adaptive seawater electrolysis electrode material and a preparation method thereof. The electrode material comprises a nickel-based substrate, a Ni-Fe (Ce)-LDH dynamic self-adaptive catalyst layer compounded on the surface layer of the nickel-based substrate, and a LaMnO porous detoxification layer covering the catalyst layer, the catalyst layer is tightly combined with the substrate through hot-pressing compounding, and the detoxification layer penetrates through the whole catalyst layer structure. The preparation method comprises the steps of substrate pretreatment, hydrothermal synthesis, hot-pressing compounding, electrochemical deposition and activating treatment, and the process is simple and controllable. The electrode does not need seawater pretreatment, has excellent catalytic activity, Cl corrosion resistance and fluctuation working condition adaptability, can realize stable operation of direct seawater electrolysis, and is suitable for hydrogen production systems of renewable energy sources such as solar energy, wind energy and the like.

Description

Technical Field

[0001] This invention belongs to the technical field of electrode materials for hydrogen production by water electrolysis, and relates to a dynamic adaptive electrolysis electrode material for seawater and its preparation method. More specifically, it relates to a dynamic adaptive electrolysis electrode material for seawater and its preparation method for use in the fluctuating conditions of renewable energy (solar energy, wind energy, etc.), which is suitable for direct seawater electrolysis scenarios without pretreatment and desalination. Background Technology

[0002] As the global energy structure shifts towards cleaner and lower-carbon energy, the scale of renewable energy power generation (solar, wind, etc.) continues to expand. However, these energy sources inherently possess intermittent and fluctuating characteristics (such as day-night cycles and fluctuations in power generation due to wind speed changes), which directly limit their compatibility with traditional water electrolysis hydrogen production systems. Meanwhile, seawater, which accounts for 97% of the Earth's surface water resources, is abundant and widely distributed compared to freshwater, eliminating the need to rely on limited freshwater resources and making it one of the ideal water sources for water electrolysis hydrogen production.

[0003] Existing seawater electrolysis technology faces two major challenges: First, Cl⁻ corrosion. High concentrations of Cl⁻ in seawater (approximately 0.5 mol / L) are prone to oxidation during electrolysis, generating Cl₂. This not only pollutes the environment but also severely corrodes the electrode catalyst layer, leading to a rapid decline in electrode activity. Second, poor adaptability to fluctuating operating conditions. Fluctuations in renewable energy power generation can cause frequent start-ups and shutdowns of the electrolysis system and sudden changes in current density, causing the electrode catalyst layer to cycle between a "reduced state (electrolysis condition) and an oxidized state (shutdown condition)." This accelerates the oxidation and corrosion of active sites and structural collapse, significantly shortening the electrode's lifespan.

[0004] To address the aforementioned issues, existing technologies primarily employ two approaches: First, pre-treating and desalinizing seawater (e.g., reverse osmosis, electrodialysis), but this increases system costs and energy consumption, reducing hydrogen production efficiency; Second, developing corrosion-resistant catalytic materials (e.g., noble metal-based catalysts, transition metal sulfides), but noble metals are expensive, transition metal materials lack structural stability under fluctuating operating conditions, and adaptive structures have not been designed for the dynamic corrosion mechanism of the "electrolysis-shutdown" cycle.

[0005] Therefore, developing an integrated electrode material that requires no seawater pretreatment and possesses both Cl⁻ corrosion resistance and dynamic adaptability to fluctuating operating conditions is of great significance for promoting the large-scale application of renewable energy hydrogen production technology. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing seawater electrode materials, such as weak resistance to Cl⁻ corrosion, poor adaptability to fluctuating operating conditions, and the need for seawater pretreatment. This invention provides an electrolytic seawater electrode material with an integrated structure of "dynamic adaptive catalytic layer-detoxification layer". The detoxification layer achieves selective adsorption and harmless conversion of Cl⁻, and the dynamic adaptive catalytic layer solves the problem of oxidation and corrosion of active sites under fluctuating operating conditions. At the same time, the invention provides a preparation method, thereby achieving stable operation of direct seawater electrolysis without pretreatment.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A dynamic adaptive seawater electrolysis electrode material is disclosed, which is used for seawater electrolysis under renewable energy fluctuation conditions. The electrode material includes a nickel-based substrate, a Ni-Fe(Ce)-LDH dynamic adaptive catalytic layer composited on the surface of the substrate, and a LaMnO3 porous detoxification layer covering the catalytic layer. The catalytic layer is Ni-Fe(Ce)-LDH, and the detoxification layer is a LaMnO3 porous structure layer, forming an integrated "dynamic adaptive catalytic layer-detoxification layer". The catalytic layer is tightly bonded to the substrate by hot-pressing composite, and the detoxification layer runs through the entire catalytic layer structure.

[0009] The nickel-based substrate adopts a nickel-based porous structure material, which is nickel fiber felt, nickel mesh, or nickel foam, wherein the thickness of the felt or mesh is 0.5mm-5mm; because the porous structure material has high conductivity, high specific surface area and good mechanical stability, it provides a supporting carrier for the catalytic layer and the detoxification layer.

[0010] The "dynamic adaptive catalytic layer" is a Ni-Fe(Ce)-LDH (LDH: Layered Double Hydroxides) catalytic layer, which is tightly bonded to the substrate through hot-pressing composite technology. Fe doping induces the growth of layered nanosheets, increases interlayer channels and specific surface area, and introduces lattice defects and unsaturated coordination sites, providing more exposed active centers for the reaction. The Ni-Ce-LDH phase can achieve Ce³⁺ / Ce under "electrolysis conditions (reduced state) - shutdown conditions (oxidized state)". 4 The dynamic reversible transformation of ⁺ forms a dual-state structure reconstruction, thereby effectively resisting the oxidative corrosion of active sites and endowing the catalyst layer with adaptability under fluctuating operating conditions.

[0011] The "detoxification layer" is a porous LaMnO3 layer structure that runs through the entire catalyst layer structure. This layer can selectively adsorb and catalytically oxidize Cl⁻, converting Cl⁻ into harmless ClO3⁻, preventing Cl⁻ from diffusing to the catalyst layer and causing corrosion. This overcomes the existing problem of Cl⁻ corrosion in seawater electrolysis and eliminates the need for seawater pretreatment and desalination.

[0012] Furthermore, in the catalyst-detoxification layer, i.e., the Ni-Fe(Ce)-LDH / LaMnO3 structure, the molar ratio of Ni-Fe(Ce)-LDH to LaMnO3 is (3-50):10; in the Ni-Fe(Ce)-LDH layer, the doping amount of Ce element is 10%-20% of the molar ratio of Ni element, which can ensure Ce³⁺ / Ce 4 The dynamic reversible transformation efficiency of ⁺ is high, while ensuring the catalytic activity of the catalyst layer. In addition, the Fe element content is 80%-90% of the molar ratio of Ni element. This ratio can ensure the formation and growth of layered nanosheets, sufficient interlayer channels and specific surface area, sufficient lattice defects and unsaturated coordination sites, and meet the active center requirements of the reaction. The preferred molar ratio of Ni-Fe(Ce)-LDH to LaMnO3 is (10-40):10.

[0013] This invention also provides a method for preparing the above-mentioned dynamic adaptive seawater electrolysis electrode material, which includes the following steps:

[0014] (1) Nickel-based substrate pretreatment: The nickel-based substrate is successively sanded, ultrasonically degreased, acid-washed and activated, rinsed with deionized water, and then dried for later use;

[0015] (2) Preparation of Ni-Fe-LDH / LaMnO3 material layer: Ni (NO3)2・6H2O, Fe (NO3)3・9H2O, La (NO3)3・6H2O and Mn (NO3)2・4H2O were dissolved in deionized water in sequence, urea was added as a precipitant, and the mixture was stirred to form a precursor solution; the nickel-based substrate pretreated in step (1) was immersed in the precursor solution, and after hydrothermal reaction, it was taken out, washed and dried to obtain the Ni-Fe-LDH / LaMnO3 material layer attached to the nickel-based substrate;

[0016] (3) Hot pressing: The material layer obtained in step (2) is placed in a hot press. Under the protection of inert gas, the temperature is controlled at 400-500℃, the pressure at 10-15MPa, and the holding time at 2-3h to achieve a tight bond between the catalyst layer and the nickel-based substrate, thus obtaining an integrated substrate-material layer.

[0017] (4) Preparation of Ni-Fe(Ce)-LDH / LaMnO3 material layer: Ce(NO3)3・6H2O and Ni(NO3)2・6H2O are dissolved in deionized water, hexamethylenetetramine is added as a complexing agent, and the pH is adjusted to 8-9 to form a deposition solution; the substrate-material layer obtained in step (3) is immersed in the deposition solution, and electrochemical deposition is performed at a voltage of 1.2-1.5V for a deposition time of 30-60min to obtain the Ni-Fe(Ce)-LDH / LaMnO3 material layer;

[0018] (5) Activation treatment: The material layer obtained in step (4) is placed in a tube furnace and calcined at 300-350℃ for 1-2 hours in an air atmosphere to generate Ce³⁺ / Ce in situ. 4 ⁺, thus obtaining an integrated substrate-“dynamic adaptive catalytic layer-detoxification layer (Ni-Fe(Ce)-LDH / LaMnO3)” electrode material.

[0019] Furthermore, in step (1), the pickling and activation are performed using a 5%-10% dilute hydrochloric acid solution for 10-15 minutes; the drying temperature is 60-80℃ and the drying time is 2-4 hours.

[0020] Further, in step (2), the concentration of Ni²⁺ in the precursor solution is 0.1-0.2 mol / L, the concentration of Fe³⁺ is 0.08-0.18 mol / L, the concentration of La³⁺ is 0.01-0.04 mol / L, the concentration of Mn²⁺ is 0.03-0.05 mol / L, and the concentration of urea is 0.5-1.0 mol / L; the hydrothermal reaction temperature is 120-150℃, and the reaction time is 8-12 h.

[0021] Further, in step (4), the Ce³⁺ concentration in the precursor solution is 0.01-0.02 mol / L, the Ni²⁺ concentration is 0.1-0.15 mol / L, and the hexamethylenetetramine concentration is 0.3-0.5 mol / L.

[0022] In step (4), a three-electrode system is used, with the substrate-material layer obtained in step (3) serving as the working electrode, the platinum sheet as the counter electrode, and the saturated calomel electrode as the reference electrode.

[0023] Beneficial effects

[0024] The present invention provides a dynamic adaptive seawater electrolysis electrode material for renewable energy fluctuation conditions. This material has an integrated structure of a "dynamic adaptive catalytic layer-detoxification layer," comprising a substrate, a dynamic adaptive catalytic layer, and a detoxification layer. This structure has the following advantages:

[0025] (1) The substrate is a nickel-based porous structure material with high conductivity, high specific surface area and good mechanical stability, which provides a support carrier for the catalytic layer and the detoxification layer;

[0026] (2) The dynamic adaptive catalyst layer is a Ni-Fe(Ce)-LDH layered material. Fe is doped into Ni to form a Ni-Fe-LDH phase, which can induce the formation and growth of layered nanosheets, increase interlayer channels and specific surface area, introduce lattice defects and unsaturated coordination sites, and provide more exposed active centers for the reaction. In addition, the Ni-Ce-LDH phase can achieve Ce³⁺ / Ce under the conditions of "electrolysis (reduced state) - shutdown (oxidized state)". 4 The dynamic reversible transformation of ⁺ forms a dual-state structure reconstruction, thereby effectively resisting the oxidation and corrosion of active sites, endowing the catalyst layer with adaptive properties under fluctuating operating conditions, and can be directly coupled with renewable energy to solve the intrinsic characteristics of renewable energy such as intermittency and fluctuation, providing a development path for the transformation of energy structure towards cleaner and lower carbon.

[0027] (3) The detoxification layer is a porous layer structure material of LaMnO3, which runs through the entire catalyst layer structure. This layer can achieve selective adsorption and catalytic oxidation of Cl⁻, converting Cl⁻ into harmless ClO3⁻, avoiding Cl⁻ from diffusing to the catalyst layer and causing corrosion. It breaks through the existing problem of Cl⁻ corrosion in seawater electrolysis, and does not require seawater pretreatment and desalination. It can be directly used as an electrolysis scenario for seawater electrolysis.

[0028] Furthermore, the preparation method of the dynamic adaptive electrolytic seawater electrode material for renewable energy fluctuation conditions provided by the present invention mainly involves pretreatment, hydrothermal synthesis, hot-pressing composite, electrochemical deposition, and activation treatment processes. The overall process exhibits characteristics of simple and controllable process, designable performance, and adaptability to large-scale production, and specifically has the following advantages:

[0029] (1) Advantages of a single process:

[0030] 1. Pretreatment is a crucial preliminary step that determines the adhesion between the material and the substrate and the degree of exposure of active sites. Firstly, it offers strong controllability, simple processes, and low cost, removing the oxide layer and impurities from the material surface and avoiding interface defects. Secondly, the introduced active groups can serve as LDH nucleation sites, significantly enhancing the adhesion between NiFe-LDH and the substrate and preventing material detachment during subsequent catalysis / energy storage. 2. Hydrothermal synthesis is the core method for LDH crystal phase construction, offering excellent structural controllability. It allows for precise control of LDH interlayer spacing, lamellar thickness, morphology, and specific surface area. It results in high purity and good crystallinity. The closed hydrothermal environment avoids the introduction of impurities, and the high temperature and pressure promote directional crystal growth, reducing amorphous phases and enhancing the intrinsic catalytic activity of LDH. The operation is simple and easily scaled up, requiring no complex vacuum / inert atmosphere protection. Laboratory batch synthesis can be directly integrated with industrial continuous hydrothermal processes.

[0031] 3. Hot-pressing composite method combines NiFe-LDH with a substrate to prepare high-density, high-mechanical-strength integrated functional materials. Through this process, tight interfacial bonding eliminates intermaterial porosity, forming mechanically interlocked or chemically bonded interfaces, thereby improving the electronic conductivity and mechanical stability of the composite material. Furthermore, this process offers strong controllability, allowing precise control of the composite material's density, porosity, and interlayer orientation, thus adapting to various application scenarios. In addition, hot-pressing composite requires no organic solvents, eliminating solvent pollution compared to solution composites, making it environmentally friendly and avoiding performance degradation caused by solvent residues.

[0032] 4. The thickness and loading of the detoxification layer prepared by electrochemical deposition are precisely controllable, avoiding waste; the deposition rate is fast and efficient, completed in minutes, and no subsequent separation and washing are required, directly forming the detoxification layer material on the substrate; it grows in situ and has strong adhesion, and combines with the catalyst layer in situ through electrochemical action, with a bonding force far exceeding that of physical coating, strong corrosion resistance, and is suitable for electrolysis of seawater under fluctuating conditions.

[0033] 5. The activation process, which enhances material activity and stability, is a crucial step in optimizing the electronic structure and defects on the material surface. Firstly, by precisely controlling the active sites, high-valence Ni³⁺ / Fe can be induced on the LDH surface. 4 - Active species are introduced, and oxygen vacancies are also introduced; secondly, thermal activation removes surface-adsorbed impurities, enhances crystal defects, and improves catalytic reaction kinetics. In the field, such steps are simple, directly applicable, and can be completed directly in an electrolytic cell without additional equipment, simplifying the process. Furthermore, stability is improved: this is because activation treatment eliminates internal stress in the material, optimizes the crystal structure, and reduces structural collapse during cycling, thereby extending the material's lifespan.

[0034] (2) Advantages of process synergy:

[0035] Overall, it exhibits advantages such as quantifiable and controllable parameters throughout the entire process, adaptability to preparation needs at different scales, and compatibility with composites of various functional materials.

[0036] 1. Quantitative control of all process parameters: From the roughness of the substrate pretreatment to the crystal phase structure of hydrothermal synthesis, and then to the defect concentration of the activation treatment, the parameters of each step can be adjusted independently, and the correspondence between the parameters and the material properties is clear, which facilitates process optimization and quality control.

[0037] 2. Adaptable to different scales of preparation needs: At the laboratory level, small-batch synthesis from mg to g scale can be achieved; at the industrial level, large-scale production from kg to ton scale can be achieved through continuous hydrothermal, roll-to-roll electrochemical deposition, and hot pressing, with minimal performance loss during process scale-up;

[0038] 3. Compatible with multiple functional materials: NiFe-LDH / graphene, NiFe-LDH / metal oxide and other composite materials can be prepared through process combinations, and the composite process is simple and controllable, without the need for complicated in-situ polymerization or doping processes.

[0039] (3) Advantages compared to other complex processes:

[0040] 1. Low equipment threshold: No high vacuum or high power equipment is required; it can be set up in a conventional laboratory.

[0041] 2. Easy to operate: No professional vacuum operation skills are required, and the experiment has high repeatability;

[0042] 3. Low cost: High utilization rate of raw materials, no expensive precursors and auxiliary reagents. Attached Figure Description

[0043] Figure 1 Examples 1-3 show the activity decay rate of conventional Ni-Fe-LDH electrodes after 100 cycles under fluctuating operating conditions;

[0044] Figure 2 The results are from the electrolysis performance tests of the conventional Ni-Fe-LDH electrode under fluctuating operating conditions in Examples 1-3. Detailed Implementation

[0045] The present invention will be further described in detail below through specific embodiments. However, it should be noted that the following embodiments are merely examples of the implementation of the present invention and are not intended to limit the scope of protection.

[0046] Example 1

[0047] A method for preparing a dynamically adaptive seawater electrolysis electrode material includes the following steps:

[0048] (1) Nickel-based substrate pretreatment: A nickel fiber felt with a thickness of 1 mm was selected as the substrate. The surface oxide scale was removed by sanding with 1000-grit sandpaper. The substrate was then placed in acetone and ultrasonically degreased for 25 min. After removal, it was immersed in 8% dilute hydrochloric acid solution for acid washing and activation for 12 min. It was then rinsed with deionized water until neutral and dried at 70℃ for 3 h for later use.

[0049] (2) Preparation of Ni-Fe-LDH / LaMnO3 material layer: Weigh 5.82g of Ni(NO3)2・6H2O, 7.27g of Fe(NO3)3・9H2O, 1.44g of La(NO3)3・6H2O, and 1.02g of Mn(NO3)2・4H2O, dissolve them in 100mL of deionized water, add 6.0g of urea (concentration 0.8mol / L), and stir for 30min to form a uniform precursor solution; immerse the pretreated nickel fiber felt in the precursor solution, place it in a hydrothermal reactor, react at 130℃ for 10h, take it out and wash it 4 times with deionized water, dry it at 70℃ for 3h to obtain Ni-Fe-LDH / LaMnO3 material layer;

[0050] (3) Hot pressing: The above material layer is placed in a hot press, protected by argon gas, and the temperature is controlled at 450℃, the pressure at 12MPa, and the holding time at 2.5h. After cooling to room temperature, it is taken out to obtain an integrated substrate-material layer.

[0051] (4) Ni-Fe(Ce)-LDH / LaMnO3 material layer: Weigh 0.65g of Ce(NO3)3・6H2O and 4.37g of Ni(NO3)2・6H2O, dissolve them in 100mL of deionized water, add 4.0g of hexamethylenetetramine (concentration 0.4mol / L), adjust the pH to 8.5 with dilute nitric acid to form a deposition solution; In addition, a three-electrode system is used, with the material layer obtained in step 3 as the working electrode, the platinum sheet as the counter electrode, and the saturated calomel electrode as the reference electrode, and deposit at a voltage of 1.3V for 45min to obtain the Ni-Fe(Ce)-LDH / LaMnO3 material layer;

[0052] (5) Activation treatment: The material layer deposited in step (4) is placed in a tube furnace and calcined at 320°C for 1.5 h in an air atmosphere. It is then naturally cooled to room temperature to form the target substrate-catalyst-detoxification layer (Ni-Fe(Ce)-LDH / LaMnO3) material electrode 1.

[0053] In this electrode material 1, the molar ratio of Ni-Fe(Ce)-LDH to LaMnO3 is 4:1, the Ce doping amount is 10% of the Ni element molar ratio, and the Fe element content is 90% of the Ni element molar ratio.

[0054] Example 2

[0055] A dynamic adaptive seawater electrolysis electrode material and its preparation method, comprising the following steps:

[0056] (1) Nickel-based substrate pretreatment: A nickel mesh with a thickness of 0.8 mm was selected as the substrate. The surface oxide scale was removed by polishing with 800-grit sandpaper. The substrate was then ultrasonically degreased in ethanol for 20 min. After removal, the substrate was immersed in 5% dilute hydrochloric acid solution for acid washing and activation for 10 min. The substrate was rinsed with deionized water until neutral and dried at 60℃ for 2 h for later use.

[0057] (2) Preparation of Ni-Fe-LDH / LaMnO3 catalyst layer: Weigh 2.91g of Ni(NO3)2・6H2O, 3.43g of Fe(NO3)3・9H2O, 0.86g of La(NO3)3・6H2O, and 0.61g of Mn(NO3)2・4H2O, dissolve them in 100mL of deionized water, add 3.0g of urea (concentration 0.5mol / L), and stir for 20min to form a uniform precursor solution; immerse the pretreated nickel mesh in the precursor solution, place it in a hydrothermal reactor, react at 120℃ for 8h, take it out and wash it 3 times with deionized water, dry it at 60℃ for 2h to obtain the Ni-Fe-LDH / LaMnO3 material layer attached to the nickel substrate;

[0058] (3) Hot pressing treatment of catalyst layer: The above materials are placed in a hot press, nitrogen gas is introduced for protection, the temperature is controlled at 400℃, the pressure is 10MPa, the holding time is 2h, and after cooling to room temperature, they are taken out to obtain an integrated substrate-material layer.

[0059] (4) Ni-Fe(Ce)-LDH / LaMnO3: Weigh 0.65g of Ce(NO3)3・6H2O and 2.91g of Ni(NO3)2・6H2O, dissolve them in 100mL of deionized water, add 3.0g of hexamethylenetetramine (concentration 0.3mol / L), adjust the pH to 8.0 with dilute nitric acid to form a deposition solution; use a three-electrode system, with the material layer obtained in step 3 as the working electrode, the platinum sheet as the counter electrode, and the saturated calomel electrode as the reference electrode, deposit at a voltage of 1.2V for 30min to obtain the Ni-Fe(Ce)-LDH / LaMnO3 material layer;

[0060] (5) Activation treatment: The deposited material is placed in a tube furnace and calcined at 300°C for 1 hour in an air atmosphere, and then naturally cooled to room temperature to obtain the target electrode material 2.

[0061] In electrode material 2, the molar ratio of Ni-Fe(Ce)-LDH to LaMnO3 is 3:1, the Ce doping amount is 15% of the Ni element molar ratio, and the Fe element content is 85% of the Ni element molar ratio.

[0062] Example 3

[0063] A dynamic adaptive seawater electrolysis electrode material and its preparation method, comprising the following steps:

[0064] (1) Nickel-based substrate pretreatment: Nickel fiber felt with a thickness of 1.2 mm was selected as the substrate. The surface oxide scale was removed by sanding with 1200 grit sandpaper. It was then placed in acetone for ultrasonic degreasing for 30 min. After removal, it was immersed in 10% dilute hydrochloric acid solution for acid washing and activation for 15 min. It was then rinsed with deionized water until neutral and dried at 80℃ for 4 h for later use.

[0065] (2) Preparation of Ni-Fe-LDH / LaMnO3 catalyst layer: Weigh 5.82g of Ni (NO3)2・6H2O, 6.46g of Fe (NO3)3・9H2O, 1.44g of La (NO3)3・6H2O, and 1.02g of Mn (NO3)2・4H2O, dissolve them in 100mL of deionized water, add 6.0g of urea (concentration 1.0mol / L), and stir for 40min to form a uniform precursor solution; immerse the pretreated nickel fiber felt in the precursor solution, place it in a hydrothermal reactor, react at 150℃ for 12h, take it out and wash it 5 times with deionized water, dry it at 80℃ for 4h to obtain the Ni-Fe-LDH / LaMnO3 material layer attached to the nickel substrate;

[0066] (3) Hot pressing treatment of catalyst layer: The above material is placed in a hot press, argon gas is introduced for protection, the temperature is controlled at 500℃, the pressure is 15MPa, the holding time is 3h, and after cooling to room temperature, it is taken out to obtain an integrated substrate-material layer.

[0067] (4) Ni-Fe(Ce)-LDH / LaMnO3: Weigh 1.31g of Ce(NO3)3・6H2O and 4.37g of Ni(NO3)2・6H2O, dissolve them in 100mL of deionized water, add 5.0g of hexamethylenetetramine (concentration 0.5mol / L), adjust the pH to 9.0 with dilute nitric acid to form a deposition solution; use a three-electrode system, with the material layer obtained in step 3 as the working electrode, the platinum sheet as the counter electrode, and the saturated calomel electrode as the reference electrode, deposit at a voltage of 1.5V for 60min to obtain the Ni-Fe(Ce)-LDH / LaMnO3 material layer;

[0068] (5) Activation treatment: The deposited material is placed in a tube furnace and calcined at 350°C for 2 hours in an air atmosphere, and then naturally cooled to room temperature to obtain the target electrode material 3.

[0069] In electrode material 3, the molar ratio of Ni-Fe(Ce)-LDH to LaMnO3 is 5:1, the Ce doping amount is 20% of the Ni element molar ratio, and the Fe element content is 80% of the Ni element molar ratio.

[0070] Performance testing

[0071] The electrode materials prepared in Examples 1-3 were subjected to direct seawater electrolysis performance tests (simulated seawater, NaCl concentration 3.5wt%), and compared with traditional Ni-Fe-LDH electrodes (without detoxification layer and Ce doping). Test conditions: electrolysis voltage 1.8V, simulated fluctuating operating conditions (current density 0-500mA / cm² cyclic switching, 30min per cycle, 100 cycles in total). The test results are as follows. Figure 1 and Figure 2 And the following table:

[0072]

[0073] Figure 1 The activity decay rate of the conventional Ni-Fe-LDH electrode after 100 cycles under fluctuating operating conditions in Examples 1-3 is given by... Figure 1 The test data in the table show that the electrode material prepared by the method of this invention exhibits an activity decay rate of only 4.5%-4.8% during seawater electrolysis, compared to 28.9% for the traditional Ni-Fe-LDH electrode. This significantly lower rate demonstrates the superior catalytic activity and stability under fluctuating operating conditions of the electrode material prepared by the method of this invention. This can be understood as the electrode material of this invention containing a dynamically adaptive catalytic layer of Ni-Fe(Ce)-LDH layered material. Doping Fe into Ni induces the formation and growth of layered nanosheets, increases interlayer channels and specific surface area, and introduces lattice defects and unsaturated coordination sites, providing more exposed active centers for the reaction. Furthermore, the Ni-Ce-LDH phase can achieve Ce³⁺ / Ce under both electrolysis conditions (reduced state) and shutdown conditions (oxidized state). 4 The dynamic reversible transformation of ⁺ leads to the reconstruction of a dual-state structure, effectively resisting oxidative corrosion of active sites and endowing the catalytic layer with adaptability to fluctuating operating conditions. This increases the catalytic activity of the electrode material of this invention. Furthermore, the activation treatment further enhances the material's catalytic activity and stability under fluctuating operating conditions. In other words, the preparation method of this invention can precisely control active sites and induce the formation of high-valence Ni³⁺ / Fe on the LDH surface.4 ⁺ Active species are introduced, along with oxygen vacancies; thermal activation treatment removes surface-adsorbed impurities and enhances crystal defects, thereby improving the catalytic reaction kinetics of this dynamically adaptive catalytic layer.

[0074] Furthermore, the data in the table also shows that no Cl₂ was detected in the electrode material prepared by this invention, while the detected Cl⁻ in the traditional Ni-Fe-LDH electrode was 12.5 mg / L. This proves that the LaMnO₃ detoxification layer of the electrode material of this invention achieves the harmless conversion of Cl⁻, effectively solving the Cl⁻ corrosion problem. This can be explained as follows: the LaMnO₃ in the detoxification layer is a porous layer structure material. Because it runs through the entire catalyst layer structure, this layer can achieve selective adsorption and catalytic oxidation of Cl⁻, converting Cl⁻ into harmless ClO₃⁻, avoiding Cl⁻ diffusion to the catalyst layer and causing corrosion. Thus, the electrode material of this invention overcomes the existing problem of Cl⁻ corrosion in seawater electrolysis, eliminating the need for seawater pretreatment and desalination, and can be directly used in seawater electrolysis scenarios.

[0075] in addition, Figure 2 The results of electrolysis performance tests conducted on conventional Ni-Fe-LDH electrodes under fluctuating operating conditions in Examples 1-3 are as follows: Figure 2 It can be seen that, under a constant voltage of 1.8V, with an initial current density similar to that of conventional electrodes, the electrode material of this invention achieves a current density of 470-438 mA / cm² after 100 cycles under fluctuating conditions, a slight decrease; while the conventional Ni-Fe-LDH electrode only reaches 320 mA / cm², a significant decrease compared to the initial current density. This demonstrates that the electrode material of this invention exhibits excellent resistance to fluctuations, effectively solving the compatibility problem with renewable energy coupling. This can be explained as follows: the preparation method of this invention allows for precise control of LDH interlayer spacing, layer thickness, morphology, and specific surface area; high temperature and high pressure facilitate directional crystal growth, reduce amorphous phases, and enhance the intrinsic catalytic activity of LDH; the thickness and loading of the detoxification layer prepared by electrochemical deposition are precisely controllable, allowing for direct formation of the detoxification layer material on the substrate; in-situ growth and strong adhesion result in in-situ bonding with the catalytic layer through electrochemical action, with a bonding force far exceeding that of physical coating, and strong corrosion resistance. Therefore, the electrode material of this invention is suitable for seawater electrolysis scenarios under fluctuating conditions.

Claims

1. A dynamic adaptive seawater electrolysis electrode material, which is used for seawater electrolysis under fluctuating renewable energy conditions, the electrode material comprising a nickel-based substrate, a Ni-Fe(Ce)-LDH dynamic adaptive catalytic layer composited on the surface of the substrate, and a LaMnO3 porous detoxification layer covering the catalytic layer, wherein, The catalyst layer is tightly bonded to the substrate by hot-pressing composite, and the detoxification layer runs through the entire catalyst layer structure.

2. The electrode material according to claim 1, characterized in that, The catalyst layer is Ni-Fe(Ce)-LDH, and the detoxification layer is a LaMnO3 porous structure layer, forming an integrated dynamic adaptive catalyst-detoxification layer structure, namely Ni-Fe(Ce)-LDH / LaMnO3 structure.

3. The electrode material according to claim 2, characterized in that, The molar ratio of Ni-Fe(Ce)-LDH to LaMnO3 is (3-50):10; in the Ni-Fe(Ce)-LDH layer, the doping amount of Ce element is 10%-20% of the molar ratio of Ni element, and the Fe content is 80%-90% of the molar ratio of Ni element.

4. The electrode material according to claim 1, characterized in that, The nickel-based substrate is made of a nickel-based porous structure material, which is one of nickel fiber felt, nickel mesh, or nickel foam.

5. A method for preparing a dynamic adaptive seawater electrolysis electrode material according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Nickel-based substrate pretreatment: The nickel-based substrate is successively sanded, ultrasonically degreased, acid-washed and activated, rinsed with deionized water, and then dried for later use; (2) Preparation of Ni-Fe-LDH / LaMnO3 material layer: Ni (NO3)2・6H2O, Fe (NO3)3・9H2O, La (NO3)3・6H2O and Mn (NO3)2・4H2O were dissolved in deionized water in sequence, urea was added as a precipitant, and the mixture was stirred to form a precursor solution; the nickel-based substrate pretreated in step (1) was immersed in the precursor solution, and after hydrothermal reaction, it was taken out, washed and dried to obtain the Ni-Fe-LDH / LaMnO3 material layer attached to the nickel-based substrate; (3) Hot pressing: The material layer obtained in step (2) is placed in a hot press. Under the protection of inert gas, the temperature is controlled at 400-500℃, the pressure at 10-15MPa, and the holding time at 2-3h to achieve a tight bond between the catalyst layer and the nickel-based substrate, thus obtaining an integrated substrate-material layer. (4) Preparation of Ni-Fe(Ce)-LDH / LaMnO3 material layer: Ce(NO3)3・6H2O and Ni(NO3)2・6H2O are dissolved in deionized water, hexamethylenetetramine is added as a complexing agent, and the pH is adjusted to 8-9 to form a deposition solution; the substrate-material layer obtained in step (3) is immersed in the deposition solution, and electrochemical deposition is performed at a voltage of 1.2-1.5V for a deposition time of 30-60min to obtain the Ni-Fe(Ce)-LDH / LaMnO3 material layer; (5) Activation treatment: The material layer obtained in step (4) is placed in a tube furnace and calcined at 300-350℃ for 1-2 hours in an air atmosphere to generate Ce³⁺ / Ce in situ. 4 ⁺, thus obtaining an integrated substrate-"dynamic adaptive catalytic layer-detoxification layer" electrode material.

6. The preparation method according to claim 5, characterized in that, In step (1), the pickling and activation are performed using a 5%-10% dilute hydrochloric acid solution for 10-15 minutes; the drying temperature is 60-80℃ and the drying time is 2-4 hours.

7. The preparation method according to claim 5, characterized in that, In step (2), the concentration of Ni²⁺ in the precursor solution is 0.1-0.2 mol / L, the concentration of Fe³⁺ is 0.08-0.18 mol / L, the concentration of La³⁺ is 0.01-0.04 mol / L, the concentration of Mn²⁺ is 0.03-0.05 mol / L, and the concentration of urea is 0.5-1.0 mol / L; the hydrothermal reaction temperature is 120-150℃, and the reaction time is 8-12 h.

8. The preparation method according to claim 5, characterized in that, In step (4), the Ce³⁺ concentration in the precursor solution is 0.01-0.02 mol / L, the Ni²⁺ concentration is 0.1-0.15 mol / L, and the hexamethylenetetramine concentration is 0.3-0.5 mol / L.

9. The preparation method according to claim 5, characterized in that, In step (4), a three-electrode system is used, with the substrate-material layer obtained in step (3) serving as the working electrode, the platinum sheet serving as the counter electrode, and the saturated calomel electrode serving as the reference electrode.

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