Chlorine-corrosion-resistant cathode for electrolyzing seawater as well as preparation method and application of chlorine-corrosion-resistant cathode

Abstract

The invention provides a chlorine corrosion resistant cathode for electrolyzing seawater as well as a preparation method and application of the chlorine corrosion resistant cathode. The preparation method comprises the following steps: S1, dissolving a cobalt salt, a nickel salt, a morphology regulating agent and a structure-directing agent in a solvent according to a molar ratio of (1-2.5): (1-2.5): (8-12): (6-10), and stirring to form a first solution; s2, a titanium mesh and the first solution are subjected to a hydrothermal reaction at the temperature of 100-150 DEG C, and CoNi layered double hydroxide with the shape of a nanoneedle array grows on the titanium mesh in situ; s3, selenium powder and a reducing agent are dissolved in a solvent according to the molar ratio of 1: (0.8-1.5) and stirred to form a second solution; and S4, carrying out hydrothermal reaction on the titanium mesh on which the CoNi layered double hydroxides grow in situ and a second solution at 150-190 DEG C so as to grow cobalt-nickel bimetallic selenide of which the morphology is a nanoneedle array in situ on the titanium mesh, thereby obtaining the chlorine corrosion resistant cathode.

Description

Technical Field

[0001] This invention relates to the field of seawater electrolysis technology, and in particular to a chlorine-resistant cathode for seawater electrolysis, its preparation method, and its application. Background Technology

[0002] Hydrogen energy, as a renewable, pollution-free, zero-carbon emission, and high-energy-density secondary energy source, is easier to store and transport than electricity. If hydrogen production is driven by the direct electrolysis of seawater through renewable energy power generation, flexible scheduling and efficient utilization of renewable energy sources such as offshore wind, solar, and tidal energy can be achieved.

[0003] Currently, Pt-based catalysts are the best performing catalysts for the hydrogen evolution reaction (HER). However, due to the scarcity and high cost of Pt, more and more non-noble metal-based catalysts are being studied, among which group VIII transition metals are particularly promising. d Orbital electrons or empty d In chemical reactions, orbitals can provide empty orbitals to act as electrophiles or lone pairs of electrons to act as nucleophiles, making it easier to form catalytic intermediates, thereby lowering the activation energy and promoting electrocatalytic reactions. Transition metal-based catalysts, such as their oxides, sulfides, phosphides, selenides, and nitrides, possess good conductivity and chemisorption capabilities, as well as diverse crystal structures, exhibiting unique electrocatalytic properties for chemical reactions. Bimetallic catalysts exhibit synergistic effects and have higher HER catalytic activity than single-metal-based catalysts. Layered double hydroxides (LDHs) have a special ionic layered structure, are elementally tunable, simple to prepare, have uniform morphology, and a large specific surface area, showing great application potential in electrocatalytic redox reactions. However, they suffer from poor conductivity and are easily corroded by chlorine in seawater, limiting their application in the electrolysis of seawater for hydrogen production.

[0004] It should be noted that the information disclosed in the background section above is only for understanding the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a chlorine-resistant corrosion-resistant cathode for seawater electrolysis, its preparation method, and its application.

[0006] The present invention adopts the following technical solution: In a first aspect, a method for preparing a chlorine-resistant cathode for seawater electrolysis is provided, comprising the following steps: S1. Dissolve cobalt salt, nickel salt, morphology modifier and structure directing agent in solvent and stir to form a first solution; wherein the molar ratio of cobalt salt, nickel salt, morphology modifier and structure directing agent is (1~2.5): (1~2.5): (8~12): (6~10); S2. The titanium mesh and the first solution in step S1 are subjected to a hydrothermal reaction at 100~150°C to grow CoNi layered double hydroxide with a morphology of nanoneedle array in situ on the titanium mesh. S3. Dissolve selenium powder and reducing agent in solvent at a molar ratio of 1:0.8~1.5 and stir to form a second solution; S4. The titanium mesh with CoNi layered double hydroxides grown in situ obtained in step S2 and the second solution in step S3 are subjected to hydrothermal reaction at 150~190°C to grow cobalt-nickel bimetallic selenide with a nanoneedle array morphology in situ on the titanium mesh, thereby obtaining the chlorine-resistant cathode.

[0007] In a second aspect, a chlorine-resistant cathode for seawater electrolysis is provided, which is prepared by the method described in the first aspect, comprising a titanium mesh and a cobalt-nickel bimetallic selenide with a morphology of a nanoneedle array grown in situ vertically on the titanium mesh.

[0008] Thirdly, the application of the chlorine-resistant corrosion-resistant cathode for seawater electrolysis described in the second aspect in the production of hydrogen from seawater electrolysis is provided.

[0009] This invention provides a chloride-resistant cathode with high activity, high stability, and long lifespan in high chloride ion environments (such as seawater), as well as its preparation and application. The beneficial effects include: This invention employs a simple two-step hydrothermal method to first prepare a 3D nanoneedle array of CoNi-LDH on a chlorine-corrosion-resistant titanium mesh, and then improves the conductivity of the CoNi-LDH through hydrothermal selenization modification. 2- Replace OH in CoNi-LDH - Cobalt-nickel bimetallic selenide is obtained. When the chlorine-resistant cathode of this invention is applied, the reaction is activated under a positive voltage, and the cobalt-nickel bimetallic selenide catalyst undergoes surface reconstruction, generating an electronegative selenate polyanion layer near the surface of the chlorine-resistant cathode. Due to Cl... - It is a weak hydrogen bond acceptor, a selenate polyanion layer and Cl - The Coulomb repulsion between them is dominant, therefore Cl - Diffusion within the polyanion layer is effectively suppressed, thereby hindering the absorption of Cl in seawater. - Contact with the catalyst prevents the chlorine-resistant cathode from being corroded by chlorine, thus improving the catalyst's stability and resistance to chlorine corrosion in seawater.

[0010] Compared to cobalt-nickel bimetallic selenide nanosheet arrays, the cobalt-nickel bimetallic selenide nanoneedle array catalyst of this invention has an open pore structure, exposing more active sites in the electrolyte, which can significantly improve the mass transfer efficiency and charge transfer rate of reactants. At the same time, its abundant surface and tip active sites make the catalyst generally superior to the easily stacked nanosheet array in terms of activity and stability, which is beneficial to improving its hydrogen evolution catalytic activity in natural seawater. Attached Figure Description

[0011] Figure 1 These are XRD patterns of titanium mesh, CoNi-LDH precursor, and Co2NiSe4 according to embodiments of the present invention.

[0012] Figure 2a This is a scanning electron microscope image of the CoNi-LDH precursor prepared according to an embodiment of the present invention.

[0013] Figure 2b This is a scanning electron microscope image of Co2NiSe4 obtained in an embodiment of the present invention.

[0014] Figure 3 Linear sweep voltammetry curves of HER for CoNi-LDH, commercially available 20% Pt / C and Co2NiSe4.

[0015] Figure 4 Tafel diagrams of the HER of CoNi-LDH and Co2NiSe4 according to the present invention.

[0016] Figure 5 This is a slope double-layer capacitance diagram of the active specific surface area of ​​the precursors CoNi-LDH and Co2NiSe4 of the present invention.

[0017] Figure 6 The precursors CoNi-LDH and Co2NiSe4 of this invention are at -10 mA cm⁻¹ -2 The CP curve was measured at the current density.

[0018] Figure 7 This is a SEM image of the comparative example nanosheet-like cobalt-nickel bimetallic selenide (Co2NiSe4).

[0019] Figure 8 This is a comparison chart of the LSV data of Co2NiSe4 in 1.04 M NaCl for the examples and comparative examples. Detailed Implementation

[0020] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of the present invention. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0021] This invention provides a method for preparing a chlorine-resistant cathode for seawater electrolysis, comprising the following steps: S1. Dissolve cobalt salt, nickel salt, morphology modifier and structure directing agent in solvent and stir to form a homogeneous first solution; wherein the molar ratio of cobalt salt, nickel salt, morphology modifier and structure directing agent is (1~2.5):(1~2.5):(8~12):(6~10); S2. The titanium mesh and the first solution in step S1 are subjected to a hydrothermal reaction at 100~150°C to grow CoNi layered double hydroxide with a morphology of nanoneedle array in situ on the titanium mesh. S3. Dissolve selenium powder and reducing agent in solvent at a molar ratio of 1:0.8~1.5 and stir to form a homogeneous second solution; S4. The titanium mesh with CoNi layered double hydroxides grown in situ obtained in step S2 and the second solution in step S3 are subjected to hydrothermal reaction at 150~190°C to grow cobalt-nickel bimetallic selenide with a nanoneedle array morphology in situ on the titanium mesh, thereby obtaining the chlorine-resistant cathode.

[0022] In some embodiments, in step S1, the cobalt salt is Co(NO3)2·6H2O, the nickel salt is Ni(NO3)2·6H2O; the molar ratio of the cobalt salt to the nickel salt is 2:1, and the cobalt-nickel bimetallic selenide is Co2NiSe4.

[0023] In some embodiments, in step S1, the morphology modifier is urea and the structure directing agent is ammonium fluoride.

[0024] In some embodiments, in step S3, the reducing agent is sodium borohydride or potassium borohydride.

[0025] In some implementations, the solvent in steps S1 and S3 is deionized water.

[0026] In some embodiments, the preparation method includes the following steps: S1. Dissolve Co(NO3)2·6H2O, Ni(NO3)2·6H2O, urea and ammonium fluoride in deionized water at a molar ratio of 2:1:10:6 and stir to form a homogeneous first solution. S2. The titanium mesh and the first solution in step S1 are subjected to a hydrothermal reaction at 100~150°C to grow CoNi layered double hydroxide with a morphology of nanoneedle array in situ on the titanium mesh. S3. Dissolve selenium powder and sodium borohydride in deionized water at a molar ratio of 1:1 and stir to form a homogeneous second solution. S4. The titanium mesh with CoNi layered double hydroxides grown in situ obtained in step S2 and the second solution in step S3 are subjected to hydrothermal reaction at 150~190°C to grow Co2NiSe4 with a nanoneedle array morphology in situ on the titanium mesh, thereby obtaining the chlorine corrosion resistant cathode.

[0027] The present invention also provides a chlorine-resistant cathode for seawater electrolysis, which is prepared by the aforementioned method and includes a titanium mesh and a cobalt-nickel bimetallic selenide with a morphology of a nanoneedle array grown in situ vertically on the titanium mesh.

[0028] In some embodiments, the needle-like structure of the nanoneedle array has a length of 1-10 μm and a root diameter of 20-100 nm.

[0029] In some embodiments, the surface of the cobalt-nickel bimetallic selenide on the titanium mesh is rough.

[0030] The present invention also provides an application of the chlorine-resistant cathode for seawater electrolysis in the production of hydrogen from seawater.

[0031] The following describes specific embodiments of the present invention.

[0032] Example In this embodiment, the method for preparing a chlorine-resistant corrosion-resistant cathode for seawater electrolysis includes the following steps: 1) The titanium mesh was ultrasonically cleaned with 1 M hydrochloric acid, anhydrous ethanol and deionized water respectively, and then vacuum dried at 60°C.

[0033] 2) Add 2 mmol of cobalt nitrate hexahydrate (Co(NO3)2·6H2O), 1 mmol of nickel nitrate hexahydrate (Ni(NO3)2·6H2O), 10 mmol of urea and 6 mmol of ammonium fluoride to 25-35 ml (30 mL in this example) of deionized water, and stir magnetically for 0.3-1.0 hours (0.5 hours in this example) to obtain a pink transparent solution; 3) Transfer the titanium mesh treated in step 1) and the solution obtained in step 2) into a high-pressure reactor and carry out a hydrothermal reaction at 120°C for 12 hours. Then, after cooling to room temperature, use water and anhydrous ethanol to ultrasonically clean away impurities that have not grown on the surface of the titanium mesh, and dry it in a vacuum oven at 60°C to obtain the precursor CoNi-LDH (CoNi layered double hydroxide). 4) Add 1 mmol selenium powder and 1 mmol sodium borohydride to 20-30 ml (30 mL in this example) of deionized water and stir magnetically for 0.2-1.0 hours (0.5 hours in this example) to obtain a dark red transparent solution; 5) The titanium mesh with CoNi-LDH grown in step 3) and the solution obtained in step 4) are transferred to a high-pressure reactor and hydrothermally reacted at 180°C for 4 hours. After cooling to room temperature, impurities not grown on the surface of the titanium mesh are ultrasonically cleaned with water and anhydrous ethanol. The mesh is then dried in a vacuum oven at 60°C to obtain a cobalt-nickel bimetallic selenide (Co2NiSe4) with a morphology of nanoneedle arrays grown on the titanium mesh.

[0034] This invention uses X-ray diffraction characterization to confirm the crystal structure and phase composition of the synthesized material. For example... Figure 1 The image shows the XRD patterns of the precursors CoNi-LDH and Co2NiSe4 grown in situ on a titanium mesh. It can be observed that, apart from the XRD peaks of the blank titanium mesh, the diffraction peaks of CoNi-LDH and Co2NiSe4 are not very obvious. This is mainly due to the amount of catalyst grown in situ on the titanium mesh (approximately 1.15 mg / cm²). -2 and 1.2 mg / cm -2 The low concentration of diffraction peaks is due to the low temperature. In the Co2NiSe4 XRD pattern, diffraction peaks were observed at 29.8°, 33.9°, 46.1°, 51.6°, and 74.4°, which matched the standard card JCPD: 04-006-5241 and corresponded to the (-401), (400), (112), (-313), and (023) crystal planes of Co2NiSe4. In the CoNi-LDH XRD pattern, diffraction peaks were observed at 30.6°, 33.8°, 36.3°, 47.2°, and 59.6°, which corresponded well to the standard card of CoNi-LDH (JCPD: 48-0083), and no other impurity phase peaks appeared. This indicates that the prepared precursor CoNi-LDH was successfully grown in situ on the titanium mesh and maintained its inherent crystal structure, laying the foundation for the excellent electrochemical stability of the chlorine-resistant cathode. No diffraction peaks of elemental selenium, cobalt, or nickel oxides, or other impurities were detected in the spectra, indicating that the CoNi-LDH precursor was mainly converted into the target selenide Co2NiSe4 through the two-step hydrothermal method, and no obvious impurity phase diffraction peaks were detected. Furthermore, all diffraction peaks were of high intensity and sharp shape, indicating that the Co2NiSe4 grown on the titanium mesh substrate had good crystallinity.

[0035] like Figure 2a and 2b The images shown are scanning electron microscope (SEM) images of the CoNi-LDH precursor and Co2NiSe4, respectively. Figure 2bAs can be seen, the precursor CoNi-LDH uniform nanoneedles grow tightly in situ on a titanium mesh substrate, with an average length of about 3 μm and a root diameter of about 50 nm. Selenization modification yields Co2NiSe4 (… Figure 2b Not only does it maintain the morphology of the nanoneedle array, but the originally smooth surface becomes rough, constructing a three-dimensional porous structure, which significantly increases the active specific surface area of ​​the material, thereby exposing more unsaturated coordinated active sites and greatly improving intrinsic catalytic activity. At the same time, the rough surface is conducive to the diffusion of reactants and the desorption of products, significantly improving mass transfer efficiency, especially in the hydrogen evolution reaction, which can reduce the bubble shielding effect.

[0036] The chlorine-resistant cathode prepared in this embodiment was subjected to electrochemical testing. The electrochemical testing conditions were as follows: testing was conducted at room temperature (approximately 26~30℃), the electrolyte was a 1.04 M NaCl solution (pH approximately 7.5), a three-electrode system was used, with a carbon rod as the counter electrode and an Ag / AgCl electrode as the reference electrode, and the working electrode was cut into 1×1 cm pieces. 2 The hydrogen evolution reaction electrode (such as a titanium mesh with Co2NiSe4 grown in situ (the chlorine-resistant cathode of the present invention), or, as a comparison, a titanium mesh with the precursor CoNi-LDH grown in situ or a commercial 20% Pt / C electrode) is directly fixed with electrode clamps to form a three-electrode system.

[0037] like Figure 3 The figure shows the linear sweep voltammetry (LSV) curves of the HER (hydrogen evolution reaction) of CoNi-LDH, commercial 20% Pt / C, and Co2NiSe4 prepared in this invention in 1.04 M NaCl. Among them, the preparation of 20% Pt / C electrode: (1) Preparation of 20% Pt / C slurry: Weigh 5 mg of 20% Pt / C using a balance, transfer it to a sample tube, and then add 450 μL of ultrapure water, 450 μL of anhydrous ethanol and 10 μL of Nafion binder solution (5%) using a pipette. Tighten the cap of the sample tube and ultrasonically disperse it in an ultrasonic machine for half an hour to obtain the slurry. (2) Take 100 μL of 20% Pt / C slurry and drop it onto a 1×1 cm 2 The titanium mesh is left to air dry at room temperature for later use.

[0038] from Figure 3 The LSV curves show that the HER performance of Co2NiSe4 obtained after selenization treatment is significantly improved compared to the precursor CoNi-LDH. At -10 mA cm⁻¹ -2 At a current density of [value missing], the voltage corresponding to Co2NiSe4 is -0.317V. vs.RHE, while the voltage corresponding to CoNi-LDH reaches -0.744 V. vs. RHE directly confirms that selenization treatment effectively enhances the intrinsic catalytic activity of the material. While commercially available 20% Pt / C, at a relatively low voltage (approximately -0.32 V),... vs. Under RHE conditions, it exhibits catalytic activity similar to Co2NiSe4, but its catalytic activity significantly decreases with increasing voltage. This may be because in corrosive electrolytes with high chloride ion concentrations, the Pt / C coated on the titanium mesh itself may be corroded, poisoning the catalyst and accelerating the failure of the overall catalyst layer. Alternatively, under high current densities, the intense hydrogen production generates huge bubble growth and desorption stress, which can easily cause precious metal particles to peel off from the support, resulting in permanent loss of active sites. Therefore, the chloride-resistant cathode of this invention has key advantages in achieving high current density and long-term stable operation.

[0039] Figure 4 The figure shows the Tafel curves of the hydrogen evolution reaction (HER) of CoNi-LDH and Co2NiSe4 in a simulated high-salt seawater environment (1.04 M NaCl). As can be seen from the figure, Co2NiSe4 exhibits significantly superior catalytic kinetics, with a Tafel slope of 124.99 mV dec. -1 The concentration was significantly lower than that of the precursor CoNi-LDH (158.18 mV dec). -1 The lower Tafel slope indicates that the HER process on the Co2NiSe4 surface has a faster reaction rate and a more efficient charge transfer mechanism, meaning that the adsorption-desorption process of hydrogen intermediates on the electrode surface is more rapid and the reaction energy barrier is lower. This superior kinetic performance can be attributed to the abundant active sites provided by the rough nanoneedle surface formed after selenization treatment.

[0040] Figure 5 In a simulated high-salt seawater environment (1.04 M NaCl), the slope double-layer capacitance (CHER) of the active specific surface area of ​​the precursors CoNi-LDH and Co2NiSe prepared in this invention is measured. dl ). Figure 5 C, measured by cyclic voltammetry, is used to assess the specific surface area of ​​electrochemical activity. dl It can be seen that the C of Co2NiSe4 dl Value (2.78 mF cm) -2 The value was significantly higher than that of its precursor CoNi-LDH (1.23 mF cm⁻¹). -2The results indicate that the material has a higher electrochemical active surface area after selenization treatment. This may be because the introduction of Se changes the microstructure of CoNi-LDH, forming Co2NiSe4 with a larger specific surface area and more active sites, which lays a solid foundation for efficient electrocatalytic HER.

[0041] Figure 6 The reaction of CoNi-LDH with Co2NiSe4 in an electrolyte of 1.04 M NaCl at -10 mA cm⁻¹ was demonstrated. -2 The chronopotential (CP) curves at the current density were obtained. The Co2NiSe4 electrode exhibited a significantly more stable potential response during the 10-hour test period, with only a slight increase in potential and no significant fluctuations, indicating its excellent electrochemical stability and corrosion resistance in harsh high-chloride electrolytes. In contrast, the potential of the CoNi-LDH electrode continuously increased and fluctuated significantly within the same time period, indicating that its active sites are easily deactivated in high-salt environments and its structural stability is poor. This result further confirms that the Co2NiSe4 nanoneedle array can effectively resist Cl... - The structural stresses during erosion and reaction processes impart the long-term operational durability required for real-world seawater electrolysis applications to the electrode materials.

[0042] Comparative example The difference from the examples lies in that the ratio of urea to ammonium fluoride is adjusted to control the generated precursor CoNi-LDH and cobalt-nickel bimetallic selenide (Co2NiSe4) to have a nanosheet structure. The preparation method of the hydrogen evolution reaction electrode for seawater electrolysis in this comparative example includes the following steps: 1) The titanium mesh was ultrasonically cleaned with 1 M hydrochloric acid, anhydrous ethanol and deionized water respectively, and then vacuum dried at 60°C.

[0043] 2) Add 2 mmol of cobalt nitrate hexahydrate (Co(NO3)2·6H2O), 1 mmol of nickel nitrate hexahydrate (Ni(NO3)2·6H2O), 15 mmol of urea and 5 mmol of ammonium fluoride to 25-35 ml (30 mL in this example) of deionized water, and stir magnetically for 0.3-1.0 hours (0.5 hours in this example) to obtain a clear solution; 3) Transfer the titanium mesh treated in step 1) and the solution obtained in step 2) into a high-pressure reactor and carry out a hydrothermal reaction at 120°C for 12 hours. Then, after cooling to room temperature, use water and anhydrous ethanol to ultrasonically clean away impurities that have not grown on the surface of the titanium mesh. Dry it in a vacuum oven at 60°C to obtain the nanosheet precursor CoNi-LDH (CoNi layered double hydroxide). 4) Add 1 mmol selenium powder and 1 mmol sodium borohydride to 20-30 ml (30 mL in this example) of deionized water and stir magnetically for 0.2-1.0 hours (0.5 hours in this example) to obtain a dark red transparent solution; 5) The titanium mesh with CoNi-LDH grown in step 3) and the solution obtained in step 4) are transferred to a high-pressure reactor and hydrothermally reacted at 180°C for 4 hours. After cooling to room temperature, impurities not grown on the surface of the titanium mesh are ultrasonically cleaned with water and anhydrous ethanol. The mesh is then dried in a vacuum oven at 60°C to obtain a cobalt-nickel bimetallic selenide (Co2NiSe4) with a nanosheet morphology grown on the titanium mesh.

[0044] like Figure 7 The image shown is a SEM image of the comparative example of nanosheet-like cobalt-nickel bimetallic selenide (Co2NiSe4).

[0045] like Figure 8 The figure shows a comparison of the LSV data of the HER of Co₂NiSe₄ nanoneedle array in the embodiment and the Co₂NiSe₄ nanosheet array in the comparative example in 1.04 M NaCl. It can be seen that the HER performance of the nanoneedle array in neutral electrolyte is much higher than that of the nanosheet array. This significant performance difference mainly stems from the combined advantages brought about by their distinctly different microstructures. The nanoneedle array, with its one-dimensional vertical orientation and open three-dimensional spatial arrangement, not only provides a higher electrochemical active surface area than the nanosheet array, exposing more active sites, but more importantly, it constructs a highly efficient mass transfer channel: its gaps facilitate the rapid diffusion of electrolyte ions and the timely desorption of product hydrogen, effectively avoiding concentration polarization caused by limited mass transfer in a neutral environment. In contrast, the nanosheet array, due to its relatively smaller specific surface area and fewer active sites compared to the needle-like structure, and its two-dimensional planar structure, is at a disadvantage in terms of mass transfer and bubble release, especially in near-neutral high-salt electrolytes where the ion migration rate is lower, further amplifying this disadvantage. Therefore, the nanoneedle array structure of the present invention has achieved comprehensive optimization in three core dimensions: the number of active sites, mass transfer kinetics, and charge transport capability, thereby exhibiting excellent and stable catalytic activity in neutral electrolytes.

[0046] This invention provides a two-step hydrothermal method for preparing a HER catalyst with chlorine corrosion resistance, stable morphology, and high specific surface area. The preparation method is simple, low-cost, and the obtained material can be used directly as an electrode without further processing, shortening the process flow from catalyst to electrode. Specifically, a 3D nanoneedle array of CoNi-LDH is first prepared in situ on a titanium mesh using a hydrothermal method. This ensures that the catalyst consists of a positively charged metal hydroxide layer and exchangeable anions as basic structural units, exhibiting a nanoneedle morphology and a relatively large specific surface area. Then, a single hydrothermal step of selenization modification yields a Co2NiSe4 nanoneedle array. The nanoneedles are densely distributed, have a rough surface, and exhibit higher catalytic activity and chlorine corrosion resistance. The preparation method of this invention is simple; the in-situ grown catalyst can be used directly as an electrode, avoiding the use of binders and reducing the electrode preparation process. This method has broad applicability.

[0047] The embodiments of the present invention have achieved significant technical progress compared with the prior art, and their technical effects are specifically reflected in the following aspects: (1) Stable electrode structure, fully exposed active sites, and high electron transport efficiency: The Co2NiSe4 catalyst is firmly bonded to the titanium mesh, which has excellent conductivity and resistance to chlorine corrosion, resulting in a stable electrode structure and preventing catalyst detachment during use. The subsequent selenization process is a chemical transformation carried out on this solid structure, and the final Co2NiSe4 electrode material remains firmly attached to the titanium mesh with intact morphology. By avoiding the polymer binder required in traditional powder catalyst coating processes, the preparation process is simplified, and more importantly, the problem of binders potentially clogging catalyst active sites and increasing interfacial resistance is eliminated. This allows the active sites of the catalyst to be fully exposed, and electron transport between the catalyst and the titanium mesh is smoother, thereby improving the overall performance of the electrode.

[0048] (2) High electrocatalytic activity and selectivity for hydrogen evolution: This effect stems from the combined effect of "selenization modification" and "three-dimensional nanoneedle array structure". First, the selenization process converts the precursor LDH into metal selenide. The introduction of selenium optimizes the electronic structure of the catalyst surface, making its adsorption energy for the hydrogen intermediate (H*) closer to the ideal value, thereby significantly improving the intrinsic catalytic activity. Second, the in-situ grown three-dimensional nanoneedle array structure has a large specific surface area, which not only provides abundant active sites, but also facilitates electrolyte penetration and rapid desorption of bubbles during the reaction, further enhancing the apparent catalytic activity.

[0049] (3) Excellent resistance to chlorine corrosion, suitable for real seawater environments: This electrode material can be directly used for electrolysis of high-chlorine electrolytes. Under positive voltage, the reaction activation occurs, and the selenate polyanion layer generated near the electrode surface can prevent Cl from being released.- It diffuses into the electrode, thus exhibiting good resistance to chlorine corrosion and extending the electrode's service life.

[0050] (4) The preparation process is simple, the cost is low and the environment is friendly: the method is simple to operate, has low equipment requirements, the raw materials are inexpensive and mild, and the safety is high.

[0051] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. A method for preparing a chlorine-resistant corrosion-resistant cathode for seawater electrolysis, characterized in that, Includes the following steps: S1. Dissolve cobalt salt, nickel salt, morphology modifier and structure directing agent in solvent and stir to form a first solution; wherein the molar ratio of cobalt salt, nickel salt, morphology modifier and structure directing agent is (1~2.5): (1~2.5): (8~12): (6~10); S2. The titanium mesh and the first solution in step S1 are subjected to a hydrothermal reaction at 100~150°C to grow CoNi layered double hydroxide with a morphology of nanoneedle array in situ on the titanium mesh. S3. Dissolve selenium powder and reducing agent in solvent at a molar ratio of 1:0.8~1.5 and stir to form a second solution; S4. The titanium mesh with CoNi layered double hydroxides grown in situ obtained in step S2 and the second solution in step S3 are subjected to hydrothermal reaction at 150~190°C to grow cobalt-nickel bimetallic selenide with a nanoneedle array morphology in situ on the titanium mesh, thereby obtaining the chlorine-resistant cathode.

2. The preparation method according to claim 1, characterized in that: In step S1, the cobalt salt is Co(NO3)2·6H2O, and the nickel salt is Ni(NO3)2·6H2O; the molar ratio of the cobalt salt to the nickel salt is 2:1, and the cobalt-nickel bimetallic selenide is Co2NiSe4.

3. The preparation method according to claim 1, characterized in that: In step S1, the morphology modifier is urea and the structure directing agent is ammonium fluoride.

4. The preparation method according to claim 1, characterized in that: In step S3, the reducing agent is sodium borohydride or potassium borohydride.

5. The preparation method according to claim 1, characterized in that: The solvent used in both steps S1 and S3 is deionized water.

6. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: S1. Dissolve Co(NO3)2·6H2O, Ni(NO3)2·6H2O, urea and ammonium fluoride in deionized water at a molar ratio of 2:1:10:6 and stir to form a homogeneous first solution. S2. The titanium mesh and the first solution in step S1 are subjected to a hydrothermal reaction at 100~150°C to grow CoNi layered double hydroxide with a morphology of nanoneedle array in situ on the titanium mesh. S3. Dissolve selenium powder and sodium borohydride in deionized water at a molar ratio of 1:1 and stir to form a homogeneous second solution. S4. The titanium mesh with CoNi layered double hydroxides grown in situ obtained in step S2 and the second solution in step S3 are subjected to hydrothermal reaction at 150~190°C to grow Co2NiSe4 with a nanoneedle array morphology in situ on the titanium mesh, thereby obtaining the chlorine corrosion resistant cathode.

7. A chlorine-resistant cathode for seawater electrolysis, characterized in that, Prepared by the preparation method according to any one of claims 1-6, comprising a titanium mesh and a cobalt-nickel bimetallic selenide with a morphology of a nanoneedle array grown in situ vertically on the titanium mesh.

8. The chlorine-resistant cathode for seawater electrolysis as described in claim 7, characterized in that, The needle-like structures of the nanoneedle array have a length of 1~10 μm and a root diameter of 20~100 nm.

9. The chlorine-resistant corrosion-resistant cathode for seawater electrolysis as described in claim 7, characterized in that, The surface of the cobalt-nickel bimetallic selenide on the titanium mesh is rough.

10. The application of the chlorine-resistant cathode for seawater electrolysis as described in claim 7 in the production of hydrogen from seawater electrolysis.

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