A hierarchical sandwich electrode configuration structure for long-period seawater electrolysis and a preparation method thereof

Abstract

The present invention discloses a hierarchical sandwich electrode configuration structure for long-cycle seawater electrolysis and a preparation method thereof. The structure includes an electrode substrate and an electrode material layer. The electrode material layer and the electrode substrate form an asymmetric sandwich structure, with one end of the electrode substrate exposed and the other end completely covered by the electrode material layer. The electrode material layer sequentially includes an inner bottom transition layer, an intermediate auxiliary layer, an intermediate active layer, and an outer protective layer from inside to outside. Among them, the bottom transition layer, the intermediate auxiliary layer, the intermediate active layer, and the outer protective layer form an asymmetric inner and outer layer structure, having a positive area component with overlapping horizontal projection areas and a non-positive area component with non-overlapping projection areas. Based on the synergistic effect of multiple components, the present invention combines with the active layer to enhance the catalytic activity and inhibit the evolution of chlorine gas. At the same time, the protective layer is used to limit the intrusion of harmful ions in the seawater environment into the electrode, improve the corrosion resistance of the electrode, and achieve stable and efficient long-cycle seawater electrolysis.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemistry, and particularly relates to a hierarchical sandwich electrode configuration structure for long-term seawater electrolysis and a preparation method thereof. Background Art

[0002] The global energy pattern is undergoing a profound transformation from relying on traditional fossil fuels to pursuing clean and efficient energy. As an ideal clean energy carrier, hydrogen can not only be used as an energy carrier to replace gasoline, diesel, etc. directly as fuel, but also be an important industrial gas. Facing the potential large-scale hydrogen demand, it is urgent to develop efficient and green hydrogen production technologies. Hydrogen production by electrolyzing water is considered the most feasible clean hydrogen production technology. However, the total volume of water on the earth is about 1.386 billion cubic kilometers, of which 96.5% is distributed in the ocean, and only about 35 million cubic kilometers is fresh water. Therefore, directly electrolyzing seawater has become a new development direction for future hydrogen production technologies.

[0003] Completely different from high-purity distilled fresh water, natural seawater is a complex system, including various inorganic ions (such as Cl - , Br - , SO4 2- , Na + , K + , Mg 2+ , Ca 2+ etc.) and marine microorganisms, which brings huge challenges to directly electrolyzing seawater, mainly manifested in the competition between the oxygen evolution reaction (OER) and the chlorine evolution reaction (CER) on the anode, and the serious corrosion of the electrode and catalyst materials by high-chlorine seawater. Based on thermodynamic analysis, OER has a lower equilibrium potential than CER, and the difference increases with the increase of pH value. Research shows that under alkaline conditions, OER can be free from CER interference in a maximum overpotential window of 490 mV. However, considering that CER is a two-electron transfer reaction and has more excellent kinetic advantages than the four-electron transfer reaction of OER, the potential reaction window of OER will be compressed during the actual electrolysis process. Therefore, developing catalysts with high activity and selectivity to effectively reduce the OER overpotential is crucial for avoiding adverse chloride chemical reactions during seawater electrolysis. In addition, there are a large number of erosive chloride ions in seawater, which can not only directly corrode the catalyst and the electrode substrate, but also damage the electrolyte environment and have a negative impact on the reaction system, seriously shortening the service life of the electrode and catalyst materials. Therefore, it is necessary to develop and design an electrode structure with high selectivity and corrosion resistance functions specifically to solve the problems of chlorine evolution and corrosion during long-term electrolysis of seawater to produce hydrogen.

[0004] Currently, in the field of seawater electrolysis, patents such as CN101956206B, CN110923738B, and CN110592608B have made effective designs in electrolysis devices. Their basic principle is to pre-treat seawater and then perform electrolysis after reaching the target conditions. The operation process is complex, increasing production costs. Therefore, there is an urgent need for electrodes that can be directly used for seawater electrolysis. Patent CN108660473B proposes an electrolytic seawater hydrogen production catalyst based on a composite nanostructure of MXene and transition metal carbides and its synthesis method, which shows excellent catalytic activity for electrolytic seawater hydrogen production. However, the catalyst is damaged after operating in seawater for 18 hours. This is mainly because this method is limited to synthesizing granular or powdered catalysts, neither specifically designing the electrode structure such as the current collector, catalyst loading method, and loading sequence, nor protecting against the corrosion of high-concentration chloride ions in seawater. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a hierarchical sandwich electrode configuration structure for long-term seawater electrolysis and its preparation method. By constructing a four-level sandwich structure of a transition layer / auxiliary layer / active layer / protective layer, the transition layer is used to enhance the binding force between the catalyst and the substrate current collector, the auxiliary layer provides reaction sites and charge transfer channels, and based on the synergistic effect of multiple components, the active layer is combined to enhance the catalytic activity and inhibit the evolution of chlorine. At the same time, the protective layer is used to limit the intrusion of harmful ions such as Cl - , Br - , F - , SO4 2- into the electrode, improve the corrosion resistance of the electrode, and achieve stable and efficient long-term seawater electrolysis.

[0006] The present invention is realized through the following technical solutions:

[0007] A hierarchical sandwich electrode configuration structure for long-term seawater electrolysis, comprising an electrode substrate and an electrode material layer. The electrode material layer and the electrode substrate form an asymmetric sandwich structure, with one end of the electrode substrate exposed and the other end completely covered by the electrode material layer;

[0008] The electrode material layer sequentially includes a bottom transition layer, an intermediate auxiliary layer, an intermediate active layer, and an outer protective layer from inside to outside. Among them, the bottom transition layer, the intermediate auxiliary layer, the intermediate active layer, and the outer protective layer are an asymmetric inner-outer layer structure, having a positive area component with overlapping horizontal projection areas and a non-positive area component with non-overlapping projection areas; the positive area component of the intermediate active layer is the smallest, the positive area component of the intermediate auxiliary layer is greater than that of the intermediate active layer and less than that of the bottom transition layer, the positive area component of the bottom transition layer is greater than that of the intermediate auxiliary layer and less than that of the outer protective layer, and the outer protective layer is arranged to cover all other electrode material layers;

[0009] The intermediate auxiliary layer and the bottom transition layer are an asymmetric sandwich structure, and the sandwich length of the intermediate auxiliary layer is less than that of the bottom transition layer;

[0010] The intermediate active layer and the intermediate auxiliary layer are an asymmetric sandwich structure, and the sandwich length of the intermediate active layer is less than that of the intermediate auxiliary layer;

[0011] The outer protective layer and the intermediate active layer are an asymmetric sandwich structure, and the sandwich length of the outer protective layer is greater than that of the bottom transition layer, the intermediate auxiliary layer, or the intermediate active layer;

[0012] The bottom transition layer uses a transition metal sulfide series catalytic material;

[0013] The intermediate auxiliary layer uses a transition metal nitride series catalytic material;

[0014] The intermediate active layer uses a transition metal double hydroxide series catalytic material;

[0015] The outer protective layer uses a mesoporous sulfur-containing manganese-based oxide series catalytic material.

[0016] Preferably, no binder and conductive agent are provided between the bottom transition layer, the intermediate auxiliary layer, the intermediate active layer, and the outer protective layer in pairs.

[0017] Preferably, the loading method of the bottom transition layer uses electrodeposition technology; the loading method of the intermediate auxiliary layer uses gas-phase reduction technology; the loading method of the intermediate active layer uses electrodeposition technology; the loading method of the outer protective layer uses in-situ growth technology.

[0018] Preferably, the transition metal sulfide series catalytic material is NiS, NiFeS, NiCoS, or NiFeCoS.

[0019] Preferably, the transition metal nitride series catalytic material is NiN, NiMoN, NiWN or NiMoWN.

[0020] Preferably, the transition metal double hydroxide series catalytic material is NiFe-LDH, NiCo-LDH or NiCoFe-LDH.

[0021] Preferably, the mesoporous sulfur-containing manganese-based oxide series catalytic material is mesoporous MnO(S), mesoporous MnO2(S) or mesoporous Mn2O3(S).

[0022] A method for preparing a layered sandwich electrode configuration structure for long-period seawater electrolysis comprises the following steps:

[0023] Step 1) Using electrodeposition technology to load the bottom transition layer:

[0024] Copper foil or aluminum foil was used as an electrode substrate for pretreatment. The copper foil or aluminum foil was ultrasonically cleaned with 1 mol / L HCl solution, ethanol and deionized water for 15 minutes respectively, and then dried for standby use. The electrolyte of the bottom transition layer was prepared. The copper foil or aluminum foil was cut into a rectangle of 3 cm × 1 cm, and an area of 1.8 cm × 1 cm was exposed to the air, and an area of 1.2 cm × 1 cm was placed in the electrolyte of the bottom transition layer. The constant current timing method was used to measure the current density at 2.0 mA / cm 2 Under the conditions of , direct current is passed, and the temperature is 20-80°C, and the deposition is carried out for 30-90 minutes, and then the electrode is taken out, rinsed with deionized water, and dried in a vacuum drying oven at 50°C for 2 hours to obtain electrode I;

[0025] Step 2) Using gas phase reduction technology to load the intermediate auxiliary layer:

[0026] Prepare a solution containing the intermediate auxiliary layer component; treat the electrode I prepared in step 1) with high temperature resistant silicone oil for protection, specifically: brush the part without the bottom transition layer and the bottom transition layer part of 0.1 cm with high temperature resistant silicone oil, expose the bottom transition layer of 1.1 cm, immerse the exposed part in a 1.3 mol / L solution containing the intermediate auxiliary layer component for 5 min, then place the sample in a tube furnace, introduce NH3 atmosphere and argon mixed gas, and start heating from room temperature to 380°C at a rate of 10°C / min after 30 min, keep it for 1 h, and take out the sample after the temperature drops to room temperature, so as to obtain electrode II;

[0027] Step 3) Using electrodeposition technology to load the intermediate active layer:

[0028] Treat and protect the electrode II prepared in step 2) with a polytetrafluoroethylene membrane. Specifically: tightly wrap the part coated with high-temperature silicone oil and the 0.1 cm middle active layer part with a polytetrafluoroethylene membrane, exposing a 1 cm long middle active layer; prepare the electrolyte for the middle active layer; use the constant current chronoamperometry method, under the condition of a current density of 2.0 mA / cm 2 , pass direct current at a temperature of 20 - 80 °C for 30 - 90 min, take it out, rinse it clean with deionized water, and dry it in a vacuum drying oven at 50 °C for 2 h to obtain electrode III;

[0029] Step 4) Load the outer protective layer by in-situ growth technology:

[0030] Remove the wrapped polytetrafluoroethylene membrane from the electrode III obtained in step 3), and use the ultrasonic technology with ethanol and deionized water to wash off the high-temperature silicone oil on the surface; prepare a solution containing the components of the outer protective layer; immerse one end of the electrode III loaded with various catalysts into the solution containing the components of the outer protective layer for a total of 1.4 cm, so that the part coated with the bottom transition layer, the middle auxiliary layer, and the middle active layer is all below the liquid level, and immerse an additional 0.2 cm length. Heat the solution to 80 °C, after reacting for 6 h, take out the electrode and wash it with deionized water, and place it in a vacuum oven to dry for 8 h to obtain a composite electrode IV with a hierarchical sandwich structure, which is the hierarchical sandwich electrode configuration structure for long-term seawater electrolysis.

[0031] The beneficial effects of the present invention are as follows:

[0032] (1) For the hierarchical sandwich electrode configuration structure for long-term seawater electrolysis of the present invention, by in-situ electrodepositing transition metal sulfides to construct the bottom transition layer, the interaction force between the electrode material layer and the substrate current collector can be enhanced, and compared with traditional adhesive electrodes, it has higher structural stability.

[0033] (2) For the hierarchical sandwich electrode configuration structure for long-term seawater electrolysis of the present invention, by loading transition metal nitrides as the middle auxiliary layer through gas-phase reduction technology, it can provide abundant active sites, and is more conducive to stimulating the catalytic activity of the active layer compared with traditional single-active layer electrodes.

[0034] (3) For the hierarchical sandwich electrode configuration structure for long-term seawater electrolysis of the present invention, by loading transition metal double hydroxides as the middle active layer through electrodeposition technology, established on the bottom transition layer and the middle auxiliary layer, it has both root stability and abundant catalytic reaction sites. In addition, as the core of the electrode, the middle active layer has the smallest positive-facing area component, and is respectively sandwiched by the bottom active layer, the middle auxiliary layer, and the outer protective layer, reducing the contact with corrosive ions. Compared with traditional single-structure electrodes, it has better catalytic selectivity and corrosion resistance at the same time.

[0035] (4) The hierarchical sandwich electrode configuration structure for long - cycle seawater electrolysis of the present invention uses mesoporous sulfur - containing manganese - based oxide loaded by in - situ growth technology as the outer protective layer, which can effectively block halogen ions such as chloride ions, bromide ions, and fluoride ions, and has the largest facing area component, which can effectively protect the underlying active layer, the intermediate auxiliary layer, and the intermediate active layer. Compared with the traditional electrode with the active layer exposed, it has stronger seawater corrosion resistance characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Is the tangent view of the hierarchical sandwich electrode configuration structure for long - cycle seawater electrolysis;

[0037] Figure 2 Is the side - cut view of the hierarchical sandwich electrode configuration structure for long - cycle seawater electrolysis;

[0038] Figure 1-2 In which: 1, electrode substrate; 2, underlying transition layer; 3, intermediate auxiliary layer; 4, intermediate active layer; 5, outer protective layer;

[0039] Figure 3 Is the linear sweep voltammetry (LSV) graph of the samples prepared in each step of Example 2 in seawater electrolyte;

[0040] Figure 4 Is the Tafel slope (Tafel) graph of the samples prepared in each step of Example 2;

[0041] Figure 5 Is the alternating current impedance spectrum of the samples prepared in each step of Example 2 in seawater electrolyte;

[0042] Figure 6 Is the cyclic capacity test of each electrode in Test Example 1 under the condition of a current density of 100 mA·cm -2 condition. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0044] Example 1

[0045] A hierarchical sandwich electrode configuration structure for long - cycle seawater electrolysis, as Figure 1 shown, includes an electrode substrate 1 and an electrode material layer. The electrode material layer and the electrode substrate 1 are in an asymmetric sandwich structure, as Figure 2 shown, one end of the electrode substrate 1 is exposed, and the other end is completely covered by the electrode material layer.

[0046] As Figure 1As shown, the electrode material layer sequentially includes a bottom transition layer 2, an intermediate auxiliary layer 3, an intermediate active layer 4, and an outer protective layer 5 from the inside to the outside, as Figure 2 As shown, the bottom transition layer 2, the intermediate auxiliary layer 3, the intermediate active layer 4, and the outer protective layer 5 are an asymmetric inner and outer layer structure, having a facing area component with overlapping horizontal projected areas and also having a non-facing area component with non-overlapping projected areas; the facing area component of the intermediate active layer 4 is the smallest, the facing area component of the intermediate auxiliary layer 3 is greater than that of the intermediate active layer 4 and less than that of the bottom transition layer 2, the facing area component of the bottom transition layer 2 is greater than that of the intermediate auxiliary layer 3 and less than that of the outer protective layer 5, and the outer protective layer 5 is arranged to cover all other electrode material layers.

[0047] The intermediate auxiliary layer 3 and the bottom transition layer 2 are an asymmetric sandwich structure, as Figure 2 As shown, having a facing area component with overlapping horizontal projected areas and also having a non-facing area component with non-overlapping projected areas, and the sandwich length of the intermediate auxiliary layer 3 is less than that of the bottom transition layer 2, and no binder and conductive agent are provided in the middle.

[0048] The intermediate active layer 4 and the intermediate auxiliary layer 3 are an asymmetric sandwich structure, as Figure 2 As shown, having a facing area component with overlapping horizontal projected areas and also having a non-facing area component with non-overlapping projected areas, and the sandwich length of the intermediate active layer 4 is less than that of the intermediate auxiliary layer 3, and no binder and conductive agent are provided in the middle.

[0049] The outer protective layer 5 and the intermediate active layer 4 are an asymmetric sandwich structure, as Figure 2 As shown, having a facing area component with overlapping horizontal projected areas and also having a non-facing area component with non-overlapping projected areas, and the sandwich length of the outer protective layer 5 is greater than that of the bottom transition layer 2, the intermediate auxiliary layer 3, or the intermediate active layer 4, and no binder and conductive agent are provided in the middle.

[0050] The bottom transition layer uses a transition metal sulfide series catalytic material, such as NiS, NiFeS, NiCoS, NiFeCoS.

[0051] The intermediate auxiliary layer uses a transition metal nitride series catalytic material, such as NiN, NiMoN, NiWN, NiMoWN.

[0052] The intermediate active layer uses a transition metal double hydroxide series catalytic material, such as NiFe-LDH, NiCo-LDH, NiCoFe-LDH.

[0053] The outer protective layer uses a mesoporous sulfur-containing manganese-based oxide series catalytic material, such as mesoporous MnO(S), mesoporous MnO2(S), or mesoporous Mn2O3(S).

[0054] Example 2

[0055] A preparation method of a hierarchical sandwich electrode configuration structure for long-term seawater electrolysis is as follows:

[0056] 1. Load the bottom transition layer (NiS) using electrodeposition technology

[0057] (1) Pretreat the copper foil (aluminum foil can also be used, taking the copper foil as an example for testing in this embodiment). Ultrasonically clean the copper foil with 1 mol / L HCl solution, ethanol, and deionized water for 15 min respectively, and dry it for later use.

[0058] (2) Configure different electrolytes according to different target products. For NiS, the electrolyte needs to be configured as follows: Weigh 0.05 - 0.15 g of Na2S2O3·5H2O (sodium thiosulfate pentahydrate), dissolve it in 20 mL of deionized water, and the obtained solution is the electrolyte required for preparing NiS; the ratio can be adjusted appropriately.

[0059] (3) Cut the copper foil into a rectangle, 3 cm × 1 cm, expose an area of 1.8 cm × 1 cm to the air, place an area of 1.2 cm × 1 cm in the above electrolyte, and use the constant current chronoamperometry method. Under the condition of a current density of 2.0 mA / cm 2 , pass a direct current, at a temperature of 20 - 80 °C, deposit for 30 - 90 min, take it out, rinse it with deionized water, and dry it in a vacuum drying oven at 50 °C for 2 h to obtain Ni / NiS.

[0060] 2. Load the intermediate auxiliary layer (NiN) using gas-phase reduction technology

[0061] Treat and protect the electrode (Ni / NiS) prepared in step 1 with high-temperature resistant silicone oil. Specifically: Brush the part without NiS and 0.1 cm of the NiS part with high-temperature resistant silicone oil to expose 1.1 cm of NiS. Immerse the exposed part in a 1.3 mol / L Ni(NO3)2·6H2O aqueous solution for 5 min, then place the sample in a tubular furnace, and introduce a mixed gas of NH3 atmosphere (110 standard milliliters / minute) and argon gas (30 standard milliliters / minute). After 30 min, start heating, from room temperature at a rate of 10 °C / min, heat up to 380 °C, hold for 1 h, and after the temperature drops to room temperature, take out the sample to obtain Ni / NiS / NiN.

[0062] 3. Load the intermediate active layer (NiFe-LDH) using electrodeposition technology

[0063] The electrode (Ni / NiS / NiN) prepared in Step 2 is protected by treating it with a polytetrafluoroethylene membrane. Specifically: the part coated with high-temperature resistant silicone oil and the 0.1 cm NiN part are tightly wrapped with a polytetrafluoroethylene membrane, exposing 1 cm of NiN; Prepare an aqueous solution of 50 mL containing 0.002 mol / L Fe(NO3)3, 0.008 mol / L Ni(NO3)2·6H2O, 0.0025 mol / L (NH4)2C2O4 (ammonium oxalate), and 0.01 mol / L Na2SO4 as the electrolyte. Using the constant current chronoamperometry method, at a current density of 2.0 mA / cm 2 , under the condition of passing a direct current, at a temperature of 20 - 80 °C, deposit for 30 - 90 min, take out, rinse thoroughly with deionized water, and dry in a vacuum drying oven at 50 °C for 2 h to obtain Ni / NiS / NiN / NiFe-LDH.

[0064] 4. Load the outer protective layer (MnO x )

[0065] Remove the wrapped polytetrafluoroethylene membrane from the electrode (Ni / NiS / NiN / NiFe-LDH) obtained in Step 3, and use ethanol and deionized water in combination with ultrasonic technology to wash off the high-temperature resistant silicone oil on the surface; Prepare an aqueous solution of 50 mL containing 0.3 g Mn(CH3COO)2·4H2O and 0.22 g urea; Immerse the end of the electrode loaded with various catalysts into the solution for a total of 1.4 cm, so that the part coated with the bottom transition layer, the middle auxiliary layer, and the middle active layer is all below the liquid level, and immerse an additional 0.2 cm in length. Heat the solution to 80 °C, after reacting for 6 h, take out the electrode and wash it with deionized water, and place it in a vacuum oven to dry for 8 h to obtain the composite electrode Ni / NiS / NiN / NiFe-LDH / MnO with a hierarchical sandwich structure x .

[0066] The catalytic performance of the electrodes obtained from the above different preparation steps 1, 2, 3, and 4 for electrolyzing seawater is as Figure 3 shown, Figure 3 which is the linear sweep voltammetry (LSV) diagram of each sample in seawater electrolyte. Figure 3 Among the curves, the sample with a lower voltage at the same current density has better catalytic performance. As can be seen from Figure 3 , the catalytic performance of pure copper foil is the worst. To reach the same current density, the required voltage is the highest, so the power consumption is the largest to achieve the same catalytic effect; As each layer of catalyst is gradually loaded, the curve of the sample becomes steeper and steeper. The fully prepared asymmetric hierarchical sandwich electrode has the best catalytic performance. To reach the same current density, the required voltage is the lowest.

[0067] Figure 4 is a Tafel slope (Tafel) graph, which represents the degree to which the electrode potential needs to be changed to achieve a certain current. The smaller the slope of the Tafel curve, the lower the overpotential of the catalytic process and the better the performance under the same kinetic current density or apparent current density. As Figure 4 shown, the pure copper foil has the largest Tafel slope and the worst catalytic performance. To reach the same current density, it requires the highest overpotential, so the power consumption is the largest to achieve the same catalytic effect. As each layer of catalyst is gradually loaded, the Tafel slope of the sample becomes smaller and smaller. The fully prepared asymmetric hierarchical sandwich electrode has the smallest Tafel slope, so it has the best catalytic performance. To reach the same current density, it requires the lowest voltage.

[0068] Figure 5 is the AC impedance spectra of the electrodes obtained from the above different preparation steps 1, 2, 3, and 4 in seawater electrolyte. The curve has a semi-circular-like feature. The smaller its diameter, the lower the charge transfer impedance and the better the electrochemical performance. As Figure 5 shown, the semi-circular diameter of the pure copper foil is the largest and the charge transfer impedance is the highest. During the electrolysis of seawater, the energy loss is the most serious, so the power consumption is the largest to achieve the same catalytic effect. As each layer of catalyst is gradually loaded, the semi-circular diameter of the sample becomes smaller and smaller. The fully prepared asymmetric hierarchical sandwich electrode has the smallest semi-circular diameter, so it has the best charge transfer ability and the lowest electrochemical energy consumption to achieve the same catalytic effect.

[0069] Test Example 1

[0070] The materials and methods described in Example 2 were used, but each layer of catalyst was loaded in a way that the projection areas were completely overlapped and stacked to prepare electrode B.

[0071] The electrode obtained in step 4 of Example 2 (named electrode A) and electrode B were simultaneously placed in seawater for a cyclic performance test under the condition of a current density of 100 mA·cm -2 . The results are as Figure 6 shown.

[0072] It can be Figure 6 seen that the asymmetric sandwich structure electrode A prepared by the present invention has a positive area component with overlapping horizontal projection areas and a non-positive area component with non-overlapping projection areas. Therefore, it can continuously electrolyze seawater for 160 h and still maintain good stability. While electrode B, which has the same four layers of catalysts but the layers are loaded in a way that the projection areas are completely overlapped and stacked, loses stability gradually after only working for 60 h under the same test conditions.

[0073] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A hierarchical sandwich electrode configuration structure for long - cycle seawater electrolysis, characterized in that, It includes an electrode substrate and an electrode material layer. The electrode material layer and the electrode substrate form an asymmetric sandwich structure, with one end of the electrode substrate exposed and the other end completely covered by the electrode material layer. The electrode material layer sequentially includes a bottom transition layer, an intermediate auxiliary layer, an intermediate active layer, and an outer protective layer from the inside to the outside. Among them, the bottom transition layer, the intermediate auxiliary layer, the intermediate active layer, and the outer protective layer form an asymmetric inner-outer layer structure, having a positive area component with overlapping horizontal projection areas and a non-positive area component with non-overlapping projection areas. The positive area component of the intermediate active layer is the smallest. The positive area component of the intermediate auxiliary layer is greater than that of the intermediate active layer and less than that of the bottom transition layer. The positive area component of the bottom transition layer is greater than that of the intermediate auxiliary layer and less than that of the outer protective layer. The outer protective layer is arranged to cover all other electrode material layers. The intermediate auxiliary layer and the bottom transition layer form an asymmetric sandwich structure, and the sandwich length of the intermediate auxiliary layer is less than that of the bottom transition layer. The intermediate active layer and the intermediate auxiliary layer form an asymmetric sandwich structure, and the sandwich length of the intermediate active layer is less than that of the intermediate auxiliary layer. The outer protective layer and the intermediate active layer form an asymmetric sandwich structure, and the sandwich length of the outer protective layer is greater than that of the bottom transition layer, the intermediate auxiliary layer, or the intermediate active layer. The bottom transition layer uses NiS. The intermediate auxiliary layer uses NiN. The intermediate active layer uses NiFe-LDH, NiCo-LDH, or NiCoFe-LDH. The outer protective layer uses mesoporous MnO x .

2. The hierarchical sandwich electrode configuration structure for long-period seawater electrolysis according to claim 1, characterized in that, No binder and conductive agent are provided between the bottom transition layer, the intermediate auxiliary layer, the intermediate active layer, and the outer protective layer.

3. A hierarchical sandwich electrode configuration structure for long-term seawater electrolysis according to claim 2, characterized in that, The loading method of the bottom transition layer uses electrodeposition technology; the loading method of the intermediate auxiliary layer uses gas-phase reduction technology; the loading method of the intermediate active layer uses electrodeposition technology; the loading method of the outer protective layer uses in-situ growth technology.

4. A method for preparing a hierarchical sandwich electrode configuration structure for long-term seawater electrolysis according to any one of claims 1-3, characterized in that It includes the following steps: Step 1) Load the bottom transition layer using electrodeposition technology: Using copper foil or aluminum foil as the electrode substrate, it is pretreated by ultrasonic cleaning with 1 mol / L HCl solution, ethanol, and deionized water for 15 min respectively, and then dried for later use; prepare the electrolyte for the bottom transition layer; cut the copper foil or aluminum foil into a rectangle, 3 cm×1 cm, expose an area of 1.8 cm×1 cm to the air, and place an area of 1.2 cm×1 cm in the electrolyte of the bottom transition layer. Using the constant current chronoamperometry method, under the condition of a current density of 2.0 mA / cm 2 , pass a direct current at a temperature of 20~80℃ for 30~90 min, take it out, rinse it with deionized water, and dry it in a vacuum drying oven at 50℃ for 2 h to obtain Electrode Ⅰ; Step 2) Load the intermediate auxiliary layer using gas-phase reduction technology: Prepare a solution containing the components of the intermediate auxiliary layer; treat and protect the electrode I prepared in step 1) with high-temperature silicone oil. Specifically: brush the part without the bottom transition layer and 0.1 cm of the bottom transition layer part with high-temperature silicone oil to expose 1.1 cm of the bottom transition layer, immerse the exposed part in a 1.3 mol / L solution containing the components of the intermediate auxiliary layer for 5 min, then place the sample in a tube furnace, introduce a mixed gas of NH3 atmosphere and argon gas, start heating after 30 min, heat from room temperature at a rate of 10 °C / min to 380 °C, keep it for 1 h, and take out the sample after the temperature drops to room temperature to obtain electrode II. Step 3) Load the intermediate active layer using electrodeposition technology: Treat and protect the electrode II prepared in step 2) with a polytetrafluoroethylene membrane. Specifically: tightly wrap the part coated with high-temperature silicone oil and the 0.1 cm middle active layer part with a polytetrafluoroethylene membrane, exposing a 1 cm long middle active layer; prepare the electrolyte for the middle active layer; using the constant current chronoamperometry method, under the condition of a current density of 2.0 mA / cm 2 , pass a direct current, deposit at a temperature of 20 - 80 °C for 30 - 90 min, take out, rinse thoroughly with deionized water, and dry in a vacuum drying oven at 50 °C for 2 h to obtain electrode III; Step 4) Load the outer protective layer using in-situ growth technology: Remove the polytetrafluoroethylene film wrapped around the electrode Ⅲ obtained in step 3), and use ethanol and deionized water in combination with ultrasonic technology to wash off the high-temperature resistant silicone oil on the surface; prepare a solution containing the components of the outer protective layer; immerse the end of the electrode Ⅲ loaded with various catalysts into the solution containing the components of the outer protective layer for a total of 1.4 cm, so that the part coated with the bottom transition layer, the middle auxiliary layer and the middle active layer is all below the liquid level, and immerse an additional 0.2 cm in length. Heat the solution to 80 °C, after reacting for 6 h, take out the electrode and wash it with deionized water, and place it in a vacuum oven for drying for 8 h to obtain the composite electrode Ⅳ with a hierarchical sandwich structure, which is the hierarchical sandwich electrode configuration structure for long-cycle seawater electrolysis.

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