Chlorine-corrosion-resistant electrode for chlorine evolution reaction as well as preparation and application of chlorine-corrosion-resistant electrode

Abstract

The invention provides a chlorine corrosion resistant electrode for chlorine evolution reaction and preparation and application thereof. The preparation method comprises the following steps: S1, solution preparation: dissolving at least two different metal salts, a morphology regulating agent and a structure-directing agent in a solvent, and stirring to form a uniform precursor solution; the metal salt at least contains cobalt salt; the molar ratio of the morphology regulating agent to the structure-directing agent to the total amount of the metal salt is (4-10): (2-8): 1; s2, precursor synthesis: putting the titanium mesh in a hydrothermal reaction environment, adding the precursor solution, and carrying out hydrothermal reaction at 100-150 DEG C for 6-12 hours so as to grow a multi-element metal hydroxide precursor with the shape of a nanoneedle array on the titanium mesh in situ; and S3, heat treatment: carrying out heat treatment on the titanium mesh loaded with the multi-element metal hydroxide precursor in an air atmosphere at 300-450 DEG C for 1-20 hours, converting the multi-element metal hydroxide precursor into a multi-element metal oxide, and keeping the morphology of the nanoneedle array to obtain the chlorine corrosion resistant electrode.

Description

Technical Field

[0001] This invention relates to the field of electrode design for chlorine evolution reactions, and in particular to a chlorine-resistant electrode for chlorine evolution reactions, its preparation, and its application. Background Technology

[0002] The chlorine evolution reaction is a core electrochemical process in the chlor-alkali industry, seawater electrolysis for chlorine production, and chlorine-containing wastewater treatment. However, the chlorine evolution reaction faces several key challenges in practical applications: First, high overpotential: Traditional chlorine evolution reaction electrodes (such as ruthenium-iridium coated titanium electrodes, DSA) have high catalytic activity, but still exhibit a certain overpotential, leading to high energy consumption. Second, insufficient catalyst stability: Especially in complex electrolyte environments (such as high chloride ion concentrations, acidity, or seawater), electrode materials are prone to chlorine corrosion, passivation, or dissolution of active components, resulting in catalytic performance degradation and shortened lifespan. Third, cost issues: High-performance DSA electrodes typically contain precious metals (such as Ru and Ir), which are expensive and limit their large-scale application.

[0003] Cobalt-nickel bimetallic hydroxides (CoNi-LDH) exhibit great potential in electrocatalysis due to their layered structure, high specific surface area, and tunable electronic structure. However, pure-phase CoNi-LDH exhibits poor conductivity, and its structural stability and catalytic selectivity (relative to the oxygen evolution reaction) are often unsatisfactory under harsh conditions of high potential and chloride ion presence. Therefore, developing a non-noble metal chloride evolution reaction electrode with high specific surface area, excellent conductivity, and stability has significant research value and application prospects.

[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 the prior art, the present invention provides a chlorine-resistant electrode for chlorine evolution reaction, its preparation and application.

[0006] In a first aspect, a method for preparing a chlorine-resistant electrode for chlorine evolution reaction is provided, comprising the following steps:

[0007] S1. Solution preparation: Dissolve at least two different metal salts, morphology modifiers and structure directing agents in a solvent and stir to form a homogeneous precursor solution; wherein, at least one of the metal salts is a cobalt salt; the molar ratio of the total amount of the morphology modifier, the structure directing agent and the metal salt is (4~10):(2~8):1;

[0008] S2. Precursor synthesis: The titanium mesh is placed in a hydrothermal reaction environment, and the precursor solution prepared in step S1 is added. The hydrothermal reaction is carried out at 100-150℃ for 6-12 hours to grow a multi-metal hydroxide precursor with a morphology of nanoneedle array in situ on the titanium mesh.

[0009] S3. Heat treatment: The titanium mesh loaded with the multi-metal hydroxide precursor obtained in step S2 is heat-treated in air at 300-450°C for 1-20 hours to convert the multi-metal hydroxide precursor into a multi-metal oxide while maintaining the nanoneedle array morphology, thus obtaining the chlorine corrosion resistant electrode.

[0010] In a second aspect, a chlorine-resistant corrosion-resistant electrode for chlorine evolution reaction is provided, which is prepared by the preparation method described in the first aspect, comprising a titanium mesh and a multi-element metal oxide grown in situ vertically on the titanium mesh, wherein the morphology of the multi-element metal oxide is a nanoneedle array.

[0011] Thirdly, the application of the chlorine-resistant electrode described in the second aspect is provided in the electrolysis of chlorine-containing electrolytes to carry out chlorine evolution reactions.

[0012] This invention, through a unique nanoneedle array structure design and the synergistic effect of multiple metals, possesses advantages such as low cost, high catalytic activity, high catalytic stability, high catalytic selectivity, resistance to chlorine corrosion, and ease of preparation. Specifically, it includes the following beneficial effects:

[0013] 1. This invention selects titanium mesh as the conductive substrate, which has the advantages of chlorine corrosion resistance and good conductivity. A precursor with the morphology of a nanoneedle array is grown in situ on the titanium mesh by hydrothermal method, and then heat-treated to generate the final multi-element metal oxide nanoneedle array structure. The multi-element metal oxide nanoneedle array structure (as a catalyst) has a very strong binding force with the titanium mesh, which prevents the catalyst from falling off the titanium mesh during the catalytic process, and significantly improves the mechanical stability and service life of the electrode.

[0014] 2. The generated multi-metal oxide nanoneedle array structure has an open three-dimensional structure, which greatly increases the specific surface area of ​​the electrode, exposes more active sites, and has excellent electrocatalytic performance. At the same time, it provides a convenient channel for the transport of reactants and products and reduces mass transfer resistance.

[0015] 3. The electrode prepared by this invention has high selectivity for the chlorine evolution reaction, and the multi-metal oxide formed by heat treatment has a stable oxide lattice structure, which can effectively fix metal cations on their lattice sites and inhibit their corrosive dissolution during the reaction process, thereby improving the stability of the catalyst and enabling it to withstand corrosion from high concentrations of chloride ions and active chlorine; at the same time, the metal sites on the surface of the multi-metal oxide are still exposed and can undergo adsorption and catalytic reactions with chloride ions.

[0016] 4. This invention uses non-precious metals, resulting in low raw material costs; the preparation process does not require complex equipment, and hydrothermal and heat treatment are mature processes. The process is simple, easy to scale up and produce, and has good industrialization prospects.

[0017] 5. The electrode prepared by this invention is self-supporting and does not require the use of binders. It can be directly used as a working electrode in an electrolytic cell, which simplifies the electrode preparation process and avoids the blockage of active sites by binders. Attached Figure Description

[0018] Figure 1a This is a scanning electron microscope image of the CoNi-LDH precursor obtained in step 2 of Example 1 of the present invention.

[0019] Figure 1b This is a scanning electron microscope image of the Co2NiO4 nanoneedle array obtained in step 3 of Example 1 of the present invention.

[0020] Figure 2 The X-ray diffraction patterns are those of the titanium mesh, CoNi-LDH precursor, and Co2NiO4 nanoneedle array in Example 1 of this invention.

[0021] Figure 3 The linear sweep voltammetry (LSV) curves of the CoNi-LDH precursor and Co2NiO4 nanoneedle array electrode in simulated concentrated seawater in 1.04 M NaCl are shown in Example 1 of this invention.

[0022] Figure 4 The image shows the Tafel curves of the CoNi-LDH precursor and Co2NiO4 nanoneedle array electrode from Example 1 of this invention in simulated concentrated seawater in 1.04 M NaCl.

[0023] Figure 5 This is the Faraday efficiency of the chlorine evolution reaction in simulated concentrated seawater containing 1.04 M NaCl, using the titanium mesh, CoNi-LDH precursor, and Co2NiO4 nanoneedle array electrode of Example 1 of this invention.

[0024] Figure 6 The value represents the double-layer capacitance of the CoNi-LDH precursor and Co2NiO4 nanoneedle array electrode in simulated concentrated seawater in 1.04 M NaCl, according to Example 1 of this invention.

[0025] Figure 7 The CoNi-LDH precursor and Co2NiO4 nanoneedle array electrode of Example 1 were tested in simulated concentrated seawater in 1.04 M NaCl at a concentration of 10 mA cm⁻¹. -2 24-hour chronopotential curves at current density.

[0026] Figure 8 This is a SEM image of the Co2NiO4 nanoneedle array electrode of Example 1 of the present invention after a 24-hour long-term stability test in simulated concentrated seawater containing 1.04 M NaCl.

[0027] Figure 9 These are the LSV curves of the chlorine evolution reaction of the corresponding CoNi oxide nanoneedle array electrodes in 1.04 M NaCl, measured at different CoNi molar ratios. Detailed Implementation

[0028] 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.

[0029] This invention provides a method for preparing a chlorine-resistant electrode for chlorine evolution reactions, comprising the following steps:

[0030] S1. Solution preparation: Dissolve at least two different metal salts, morphology modifiers and structure directing agents in a solvent and stir to form a homogeneous precursor solution; wherein, at least one of the metal salts is a cobalt salt; the molar ratio of the total amount of the morphology modifier, the structure directing agent and the metal salt is (4~10):(2~8):1;

[0031] S2. Precursor synthesis: The titanium mesh is placed in a hydrothermal reaction environment, and the precursor solution prepared in step S1 is added. The hydrothermal reaction is carried out at 100-150℃ for 6-12 hours to grow a multi-metal hydroxide precursor with a morphology of nanoneedle array in situ on the titanium mesh.

[0032] S3. Heat treatment: The titanium mesh loaded with the multi-metal hydroxide precursor obtained in step S2 is heat-treated in air at 300-450°C for 1-20 hours to convert the multi-metal hydroxide precursor into a multi-metal oxide while maintaining the nanoneedle array morphology, thus obtaining the chlorine corrosion resistant electrode.

[0033] In the above embodiment, the hydrothermal reaction temperature in step S2 is selected as 100-150℃, which can control the morphology of the generated precursor to be a nanoneedle array. If the temperature is below 100℃, the activity and nucleation rate of the reactant ions are too low, resulting in an excessively long reaction cycle and difficulty in forming a product with good crystallinity and uniform morphology. If the temperature is too high (e.g., >150℃), the pressure of the reaction system increases sharply, the reaction kinetics are too fast, resulting in a large number of instantaneous nucleations, which can easily generate unwanted impurity phases (such as metal oxides of other crystal forms) and cause crystal growth to run out of control, forming irregular particle agglomerates instead of a uniform nanoneedle array. At the same time, the excessively high temperature also places higher pressure requirements on the reaction vessel, increasing costs and risks.

[0034] In the above embodiments, the heat treatment temperature in step S3 is selected as 300-450℃. This allows the generated product to maintain the original nanoneedle structure of the precursor, resulting in a nanoneedle array structure with a large specific surface area and abundant catalytic active sites. If the temperature is below 300℃, the precursor will not decompose completely, and a large number of amorphous components and impurities will exist in the material, leading to a decrease in its conductivity and structural stability. If the temperature exceeds 450℃, the nanoneedle array structure will undergo significant sintering and coarsening due to its high surface energy, causing the nanoneedle tips to disappear, or even break and aggregate, leading to the collapse of the nanoneedle array structure. This, in turn, results in the loss of its tip effect and high specific surface area, affecting its catalytic activity.

[0035] In some embodiments, in step S1, the metal salt further includes at least one of nickel salt, iron salt, and manganese salt; the morphology modifier is urea; and the structure directing agent is ammonium fluoride.

[0036] In some embodiments, in step S1, the metal salt is a cobalt salt and a nickel salt, and the molar ratio of the cobalt salt to the nickel salt is 2.5:1 to 1:2.5.

[0037] In some embodiments, in step S1, the metal salt is a cobalt salt and an iron salt, and the molar ratio of the cobalt salt to the iron salt is 2:1; or, in step S1, the metal salt is a cobalt salt and a manganese salt, and the molar ratio of the cobalt salt to the manganese salt is 2:1.

[0038] In some embodiments, in step S1, the metal salt is a cobalt salt, a nickel salt, and an iron salt, and the molar ratio of the cobalt salt, nickel salt, and iron salt is 1:1:1; or, in step S1, the metal salt is a cobalt salt, a nickel salt, and a manganese salt, and the molar ratio of the cobalt salt, nickel salt, and manganese salt is 1:1:1.

[0039] In some embodiments, the heat treatment in step S3 is performed in an oxygen-containing atmosphere.

[0040] In some embodiments, the heat treatment in step S3 is also carried out under a phosphorus source or a sulfur source to obtain a phosphorus-doped or sulfur-doped multi-metal oxide.

[0041] In some embodiments, the preparation method of the three-dimensional Co2NiO4 nanoneedle array electrode for the chlorine evolution reaction includes the following steps:

[0042] (1) Preparation of precursor solution: Dissolve cobalt salt, nickel salt, urea and ammonium fluoride in deionized water and stir until completely dissolved to form a homogeneous precursor solution. The molar ratio of cobalt salt to nickel salt is 2.5:1 to 1:2.5. Urea is used as a morphology modifier and ammonium fluoride is used as a structure directing agent. The molar ratio of urea, ammonium fluoride and total metal salt is (4~10):(2~8):1.

[0043] (2) Hydrothermal synthesis of CoNi-LDH precursor: The cleaned titanium mesh was placed in a high-pressure reactor lined with polytetrafluoroethylene, and the precursor solution prepared in step (1) was poured in. After sealing, a hydrothermal reaction was carried out. The hydrothermal reaction temperature was 100-150℃, and the reaction time was 6-12 hours. After the reaction was completed, the mixture was naturally cooled to room temperature. The titanium mesh was then removed, washed repeatedly with deionized water and ethanol, and then dried at 40-60℃ to obtain the CoNi-LDH precursor array grown in situ on the titanium mesh.

[0044] (3) Thermal decomposition treatment: The titanium mesh loaded with CoNi-LDH obtained in step (2) above is placed in a tube furnace and heat-treated in an air atmosphere. The heat treatment temperature is 300-450℃, the heating rate is 2-5℃ / min, and the holding time is 1-4 hours. After the heat treatment is completed, it is naturally cooled to room temperature, and the target product (three-dimensional Co2NiO4 vertical nanoneedle array) is obtained on the titanium mesh substrate.

[0045] This invention also provides a chlorine-resistant corrosion-resistant electrode for the chlorine evolution reaction, prepared by the aforementioned method. It comprises a titanium mesh and a multi-element metal oxide grown in situ vertically on the titanium mesh, wherein the multi-element metal oxide has a nanoneedle array morphology. In the electrode prepared by the method of this invention, the multi-element metal oxide grows vertically, uniformly, and firmly on the titanium mesh in the form of a vertical nanoneedle array, forming a three-dimensional interconnected structure. The needle-like structures of the nanoneedle array have a length of 1–10 μm and a root diameter of 20–100 nm. This unique structure has a large specific surface area, providing abundant catalytic active sites, and also facilitates electrolyte penetration and product removal.

[0046] The present invention also provides an application of the chlorine-resistant electrode described above in the electrolysis of chlorine-containing electrolytes (such as seawater) to carry out a chlorine evolution reaction.

[0047] The following describes specific embodiments of the present invention.

[0048] The titanium mesh used in the following embodiments underwent the following pretreatment: a 3 cm × 4 cm titanium mesh was ultrasonically cleaned for 15 minutes each in acetone, ethanol and deionized water to remove surface grease and impurities, and then dried in a forced-air oven at 50°C for later use.

[0049] Example 1

[0050] 1. Preparation of precursor solution: Weigh metal salt (2 mmol Co(NO3)2·6H2O and 1 mmol Ni(NO3)2·6H2O), 10 mmol urea and 6 mmol NH4F, dissolve in 60 mL deionized water, and stir magnetically for 30 minutes until completely dissolved.

[0051] 2. Hydrothermal Reaction: A titanium mesh was placed in a 100 mL PTFE-lined stainless steel high-pressure reactor, and the aforementioned precursor solution was poured in (the titanium mesh was completely immersed in the precursor solution). The reactor was sealed and placed in a forced-air drying oven, where it was reacted at 120°C for 12 hours. After the reaction, the reactor was allowed to cool naturally. The titanium mesh was then removed, thoroughly washed with deionized water and ethanol, and dried in a forced-air drying oven at 60°C for 12 hours to obtain a pinkish-purple CoNi-LDH precursor grown in situ on the titanium mesh.

[0052] 3. Thermal decomposition treatment: The titanium mesh loaded with the precursor was placed in a tube furnace and heated to 400°C at a rate of 5°C / min under air atmosphere, and held at this temperature for 3 hours. It was then naturally cooled to room temperature to obtain a black three-dimensional Co2NiO4 nanoneedle array electrode.

[0053] like Figure 1a The image shown is a scanning electron microscope image of the CoNi-LDH precursor obtained in step 2 of this embodiment. Figure 1b The image shown is a scanning electron microscope image of the Co2NiO4 nanoneedle array electrode prepared in step 3 of this embodiment. It can be observed from the image that the slender nanoneedles grow vertically on the surface of the titanium mesh, forming a dense, orderly and open three-dimensional vertical array structure. The length of the needle structure is more than 2 micrometers and the maximum diameter of the root is about 50 nanometers.

[0054] Figure 2 This is the X-ray diffraction pattern of the titanium mesh, CoNi-LDH precursor, and Co2NiO4 nanoneedle array in this embodiment. The CoNi-LDH in the pattern matches the standard card JCPDS No. 48-0083, and the Co2NiO4 diffraction peak matches the standard card JCPDS No. 02-1074, confirming the phase composition of the catalyst.

[0055] Electrochemical tests were performed using the CoNi-LDH precursor and Co2NiO4 nanoneedle array as electrodes in the examples. All electrochemical data measured in this paper were obtained using a three-electrode system (the counter electrode and reference electrode were a carbon rod and an Ag / AgCl electrode, respectively; the working electrode was cut into 1×1 cm pieces). 2 The titanium mesh with CoNi-LDH precursor or Co2NiO4 grown in situ on the area of ​​the electrode was directly fixed with electrode clamps to form a three-electrode system. The results were obtained by testing in simulated concentrated seawater composed of 1.04 M NaCl solution to verify the chlorine evolution catalytic activity and structural stability of the Co2NiO4 nanoneedle array electrode under high corrosiveness and high reactant concentration environment.

[0056] Figure 3 The linear sweep voltammetry (LSV) curves of the CoNi-LDH precursor and the Co2NiO4 nanoneedle array electrode in simulated concentrated seawater in 1.04 M NaCl are shown. The curves show that the Co2NiO4 nanoneedle array electrode generates a significant chlorine evolution current at a low potential, exhibiting a low onset potential and overpotential.

[0057] Figure 4 The figures show the Tafel curves of the CoNi-LDH precursor and the Co2NiO4 nanoneedle array electrode in simulated concentrated seawater in 1.04 M NaCl. The curves show that the Co2NiO4 nanoneedle array electrode has a smaller Tafel slope, indicating that it has better charge transfer efficiency and faster reaction kinetics.

[0058] Figure 5 This figure shows the Faradaic efficiency of the chlorination reaction in simulated concentrated seawater containing 1.04 M NaCl, using a titanium mesh, CoNi-LDH precursor, and Co2NiO4 nanoneedle array electrode. The figure indicates that the Faradaic efficiency of Co2NiO4 is as high as 92.46%, exhibiting higher selectivity for the chlorination reaction compared to CoNi-LDH and the titanium mesh. The Faradaic efficiency was tested using a chronopotentiostatic method (CP) at a current density of 10 mA / cm². 2 The electrolysis time was 15 min. After electrolysis, the electrolyte was sealed and ready for testing. 5 ml of electrolyte was added to an iodine flask, followed by 1 mL of a solution containing 20% ​​KI and 0.5% H₂SO₄. The solution was titrated with 0.01 M sodium thiosulfate solution until colorless. The Faraday efficiency of the electrode was calculated. Where n is the sampling multiple, F is the Faraday constant (96485 C / mol), C is the concentration of sodium thiosulfate solution (0.01 M), V is the titration amount of sodium thiosulfate solution (L), I is the current value (A), and t is the electrolysis time (s). Reference: "Xu Haoran, Chen Zhen, Feng Xiangdong, et al. Study on treatment of industrial ammonia nitrogen wastewater with modified titanium-based DSA electrode [J]. Applied Chemical Industry, 2022, 51(S02):177-181."

[0059] Figure 6 This represents the electric double-layer capacitance of the CoNi-LDH precursor and the Co2NiO4 nanoneedle array electrode in simulated concentrated seawater in 1.04 M NaCl, as described in this embodiment. Since the active specific surface area is directly proportional to the electric double-layer capacitance, the magnitude of the electric double-layer capacitance is used to compare the catalyst activity. It is evident that Co2NiO4 has a larger active specific surface area.

[0060] Figure 7 The CoNi-LDH precursor and Co2NiO4 nanoneedle array electrode of this embodiment were tested in simulated concentrated seawater in 1.04 M NaCl at a concentration of 10 mA cm⁻¹. -2 The 24-hour chronopotential curves at current density show that the Co2NiO4 electrode maintains a stable potential during long-term electrolysis, with a much smaller potential decay than the CoNi-LDH electrode, demonstrating its excellent stability.

[0061] Figure 8 This is a SEM image of the Co2NiO4 nanoneedle array electrode from this embodiment after a 24-hour long-term stability test in simulated concentrated seawater containing 1.04 M NaCl. Observation shows that after the long-term stability test, the nanoneedle structure of Co2NiO4 remained intact and undamaged, indicating its excellent resistance to chlorine corrosion.

[0062] In other variations of Example 1, step 1 was performed using different Co:Ni molar ratios (Co:Ni = 2:1 in Example 1, and Co:Ni = 2.5:1, Co:Ni = 1:1, Co:Ni = 1:2, and Co:Ni = 1:2.5 in the four variations) to prepare the corresponding CoNi oxide nanoneedle array electrodes. Figure 9 The figure shows the LSV curves of the chlorine evolution reaction in 1.04 M NaCl for the corresponding CoNi oxide nanoneedle array electrodes at different CoNi molar ratios. It can be seen that Co:Ni = 2:1 is the optimal ratio.

[0063] This embodiment has the following advantages:

[0064] (1) In-situ growth with strong bonding force: The precursor is grown in situ on the titanium mesh by hydrothermal method, which makes the final Co2NiO4 nanoneedle array have a very strong bonding force with the titanium mesh, avoiding the catalyst from falling off the substrate during the catalytic process, and significantly improving the mechanical stability and service life of the electrode.

[0065] (2) Unique three-dimensional nanoneedle array structure: The vertical nanoneedle array forms an open three-dimensional structure, which greatly increases the specific surface area of ​​the electrode, exposes more active sites, and provides a convenient channel for the transport of reactants and products, reducing mass transfer resistance.

[0066] (3) Excellent electrocatalytic performance and high catalytic activity: Co2NiO4 has a higher intrinsic conductivity than its precursor CoNi-LDH, which accelerates electron transport. The electronic structures of Co and Ni are coupled and optimized, exhibiting a synergistic effect. In Co2NiO4, electrons tend to partially transfer from Co sites to Ni sites. This interaction modulates the local electron density of the active sites, making the adsorption energy of the reaction intermediates approach an ideal value—ensuring effective activation of the reactants while facilitating the desorption of the final product, chlorine molecules, thus significantly reducing the energy barrier of the entire reaction. Simultaneously, the coexistence of Co and Ni stabilizes the mixed valence state (e.g., Co...). 2+ / Co 3+ and Ni 2+ / Ni 3+ Together, they construct an efficient electron transport channel, significantly improving intrinsic conductivity and enhancing chlorine evolution catalysis performance from both thermodynamic (optimized adsorption) and kinetic (accelerated electron transport) perspectives.

[0067] (4) High selectivity: Co2NiO4 exhibits high selectivity for the chlorine evolution reaction, with a Faradaic efficiency of up to 92.46% in a simulated seawater electrolyte containing 1.04 M NaCl. This effectively suppresses side reactions (especially the oxygen evolution reaction), which is particularly important for direct electrolysis of seawater (containing a large amount of competitive OH groups). - It is crucial in the application of ions.

[0068] (5) Excellent stability and corrosion resistance: The heat-treated Co2NiO4 has a stable oxide lattice structure, which can effectively fix Co and Ni cations on its lattice sites and inhibit their corrosive dissolution during the reaction process, thereby improving the stability of the catalyst and enabling it to withstand corrosion from high concentrations of chloride ions and active chlorine. At the same time, the Co and Ni sites on the surface of the oxide are still exposed and can undergo adsorption and catalytic reactions with chloride ions.

[0069] (6) Low cost and simple process: Non-precious metals are used, and the raw material cost is low; the preparation process does not require complicated equipment, and hydrothermal and heat treatment are mature processes that are easy to scale up and produce, and have good industrialization prospects.

[0070] (7) Direct application: The prepared electrode is self-supporting and does not require the use of binder. It can be directly used as a working electrode in an electrolytic cell, which simplifies the electrode preparation process and avoids the blockage of active sites by binder.

[0071] The three-dimensional Co2NiO4 nanoneedle array electrode prepared by this invention, in addition to its common applications such as electrocatalysis, supercapacitors, and lithium-ion batteries, may also be applied in the following technological fields: electrochemical sensing, environmental remediation (e.g., as an adsorbent or catalyst for water treatment), optoelectronic devices, and biomedicine (e.g., biosensors or drug delivery carriers). These applications are based on the material's high specific surface area, good conductivity, and stable structure. The method of this invention provides these fields with a low-cost, high-performance electrode material.

[0072] Example 2

[0073] The difference from Example 1 is that Ni(NO3)2·6H2O in step 1 is replaced with Fe(NO3)3·9H2O, a CoFe-LDH precursor is obtained in step 2, and a three-dimensional Co2FeO4 nanoneedle array electrode is obtained in step 3.

[0074] Example 3

[0075] The difference from Example 1 is that Ni(NO3)2·6H2O in step 1 is replaced with Mn(NO3)2·4H2O, a CoMn-LDH precursor is obtained in step 2, and a three-dimensional Co2MnO4 nanoneedle array electrode is obtained in step 3.

[0076] Example 4

[0077] The difference from Example 1 is that in step 1, the metal salts are cobalt salt, nickel salt, and iron salt, with a molar ratio of Co:Ni:Fe:urea:ammonium fluoride = 1:1:1:10:6. In step 2, a CoNiFe-LDH precursor is obtained, and in step 3, a ternary metal oxide CoNiFeO4 nanoneedle array is finally grown on a titanium mesh.

[0078] Example 5

[0079] The difference from Example 1 is that in step 1, the metal salts are cobalt salt, nickel salt, and manganese salt, with a molar ratio of Co:Ni:Mn:urea:ammonium fluoride = 1:1:1:10:6. In step 2, a CoNiMn-LDH precursor is obtained, and in step 3, a ternary metal oxide CoNiMn4 nanoneedle array is finally grown on a titanium mesh.

[0080] Example 6

[0081] The difference from Example 1 is that in step 3, a phosphorus or sulfur source is placed upstream of the air-introduced tubular furnace, and a titanium mesh loaded with the precursor is placed downstream. The furnace is heated to 400°C at a rate of 5°C / min under air atmosphere and held at this temperature for 3 hours. It is then allowed to cool naturally to room temperature. This yields a phosphorus-doped or sulfur-doped metal oxide nanoneedle array with higher catalytic activity.

[0082] Example 7

[0083] The difference from Example 1 is that in step 2, the hydrothermal reaction time is extended from 12 hours to 15-20 hours, which can yield a longer and thicker nanoneedle array, making the spacing between the nanoneedle arrays smaller. In subsequent applications, the surface and active sites of the catalyst are more exposed in the electrolyte.

[0084] 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 electrode for chlorine evolution reaction, characterized in that, Includes the following steps: S1. Solution preparation: Dissolve at least two different metal salts, morphology modifiers and structure directing agents in a solvent and stir to form a homogeneous precursor solution; wherein, at least one of the metal salts is a cobalt salt; the molar ratio of the total amount of the morphology modifier, the structure directing agent and the metal salt is (4~10):(2~8):1; S2. Precursor synthesis: The titanium mesh is placed in a hydrothermal reaction environment, and the precursor solution prepared in step S1 is added. The hydrothermal reaction is carried out at 100-150℃ for 6-12 hours to grow a multi-metal hydroxide precursor with a morphology of nanoneedle array in situ on the titanium mesh. S3. Heat treatment: The titanium mesh loaded with the multi-metal hydroxide precursor obtained in step S2 is heat-treated in air at 300-450°C for 1-20 hours to convert the multi-metal hydroxide precursor into a multi-metal oxide while maintaining the nanoneedle array morphology, thus obtaining the chlorine corrosion resistant electrode.

2. The preparation method according to claim 1, characterized in that: In step S1, the metal salt further includes at least one of nickel salt, iron salt, and manganese salt; the morphology modifier is urea; and the structure directing agent is ammonium fluoride.

3. The preparation method according to claim 1 or 2, characterized in that: In step S1, the metal salt is a cobalt salt and a nickel salt, and the molar ratio of cobalt salt to nickel salt is 2.5:1 to 1:2.

5.

4. The preparation method according to claim 1 or 2, characterized in that: In step S1, the metal salt is a cobalt salt and an iron salt, and the molar ratio of the cobalt salt to the iron salt is 2:1; or, in step S1, the metal salt is a cobalt salt and a manganese salt, and the molar ratio of the cobalt salt to the manganese salt is 2:

1.

5. The preparation method according to claim 1 or 2, characterized in that: In step S1, the metal salt is a cobalt salt, a nickel salt, and an iron salt, and the molar ratio of the cobalt salt, nickel salt, and iron salt is 1:1:1; or, in step S1, the metal salt is a cobalt salt, a nickel salt, and a manganese salt, and the molar ratio of the cobalt salt, nickel salt, and manganese salt is 1:1:

1.

6. The preparation method according to claim 1 or 2, characterized in that: The heat treatment in step S3 is carried out in an oxygen-containing atmosphere.

7. The preparation method according to claim 6, characterized in that: The heat treatment in step S3 is also carried out under a phosphorus source or a sulfur source to obtain phosphorus-doped or sulfur-doped multi-metal oxides.

8. A chlorine-resistant electrode for chlorine evolution reaction, characterized in that, The preparation method according to any one of claims 1-7 is used to prepare the product, which includes a titanium mesh and a multi-element metal oxide grown in situ vertically on the titanium mesh, wherein the morphology of the multi-element metal oxide is a nanoneedle array.

9. The electrode as claimed in claim 8, 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.

10. The application of a chlorine-resistant electrode as described in any one of claims 8-9 in the electrolysis of chlorine-containing electrolytes to carry out a chlorine evolution reaction.

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