Catalyst for electrooxidation of chlorine-containing electrolyte as well as preparation method and application of catalyst

Abstract

The invention provides a catalyst for electrooxidation of chlorine-containing electrolyte and a preparation method and application thereof, the catalyst comprises a layered double hydroxide-rare earth basic carbonate heterojunction grown on a nickel substrate in situ, and the nickel substrate is foamed nickel with the surface modified by nickel. On the basis of a strategy for constructing selective adsorption sites capable of distinguishing Cl <-> and OH <->, preferential adsorption of OH <-> is realized by introducing rare earth basic carbonate (RE (OH) CO3), so that the chloride ion corrosion resistance of the material in seawater electrolysis is remarkably enhanced. The heterostructure not only has oxygen evolution reaction activity superior to that of traditional LDH, but also shows excellent structural stability and continuous corrosion resistance under the industrial-grade current density, and a feasible material solution is provided for promoting industrial application of a seawater electrolysis technology.

Description

Technical Field

[0001] This invention belongs to the field of seawater electrolysis hydrogen production technology, and relates to a catalyst for the electro-oxidation of chlorine-containing electrolytes, its preparation method and application. Background Technology

[0002] Hydrogen energy is considered an ideal alternative to fossil fuels due to its high energy density and zero emissions. While seawater electrolysis can alleviate freshwater dependence, the high concentration of chloride ions in seawater competes with the oxygen evolution reaction (OER) and causes severe corrosion, posing a technological bottleneck.

[0003] Compared to the high cost of precious metal catalysts, layered hydrogen hydroxides (LDHs) composed of transition metal elements offer advantages such as low cost, high activity, and tunable structure as non-precious metal catalysts. However, in alkaline seawater electrolysis environments, especially under high current density conditions, localized OH groups... - Rapid consumption of chloride ions leads to acidification of the electrode interface microenvironment, exacerbates the competitive adsorption of chloride ions on active sites, triggers the chloride oxidation side reaction (ClOR), and accelerates catalyst corrosion, severely restricting the long-term stability of LDH.

[0004] Currently, existing technologies for improving the stability of LDH anodes in seawater electrolysis mainly include strategies such as surface chloride ion repulsion, corrosion protection layer construction, and surface chloride ion fixation.

[0005] For example, Adv. Mater, 2024, 36, e2411302 reported a method for preparing barium (Ba)-doped NiFe-LDH. This method introduces barium nitrate into the solvothermal system of NiFe-LDH, synthesizing NiFeBa-LDH through a one-step reaction. This material utilizes Ba... 2+ Anchoring SO4 in electrolyte 2- In situ, a BaSO4 protective layer is formed to block Cl. - The erosion process enhances the activity and stability of the OER to some extent. However, under industrial-grade current densities, the intense ion flow and continuous impact of bubbles can easily cause the BaSO4 protective layer to physically peel off, thus losing its protective function and making it difficult to maintain a long-term stable chloride ion repulsion function.

[0006] Another study, Ind. Eng. Chem. Res., 2023, 62, 19674-19682, reported a method for molybdenum (Mo)-doped NiFe-LDH. This method involves doping molybdate ions (MoO4) with NiFe-LDH. 2– Molybdenum-doped materials (Mo) were prepared by intercalating molybdenum into nickel-iron layered double hydroxide (NiFe-LDH). x -NiFe-LDH). High-valence molybdenum (VI) can modulate the electronic structure of nickel and iron, promoting the production of more Ni.3+ The formation of active sites accelerates the self-reconstruction of the material into a highly active NiOOH phase during the oxygen evolution reaction (OER), significantly enhancing catalytic activity; the steric hindrance and electrostatic repulsion effect of molybdate ions effectively block chloride ions (Cl... - The proximity to the catalytic active sites enhances the stability of the catalyst in seawater electrolysis systems. However, at industrial-grade current densities, drastic pH fluctuations at the electrode interface weaken the electrostatic repulsion, leading to a significant decrease or even complete failure of the repulsion effect, leaving the catalyst still at risk of corrosion.

[0007] In summary, under industrial-grade current density conditions, existing seawater electrolysis corrosion resistance strategies, including chloride ion repulsion strategies, protective layer construction strategies, and other strategies, still face severe challenges in application. For example, protection strategies fail under high current conditions, and most solutions are only tested in idealized laboratory three-electrode systems, failing to demonstrate their effectiveness and stability in devices close to actual industrial applications (such as anion exchange membrane AEM electrolyzers). The verification and transformation from laboratory conditions to actual devices has not yet been completed.

[0008] Therefore, developing LDH materials that can combine high catalytic activity, long-term corrosion resistance and economic feasibility at high current densities has become a key bottleneck issue in promoting the development of this field. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to provide a catalyst for the electro-oxidation of chlorine-containing electrolytes, its preparation method, and its applications. This invention is based on constructing a catalyst capable of distinguishing Cl... - With OH - To explore a strategy for selective adsorption sites, a novel layered double hydroxide-rare earth basic carbonate heterocatalyst is proposed. This catalyst achieves selective adsorption of OH- by introducing rare earth basic carbonate (RE(OH)CO3). - The preferential adsorption of chloride ions significantly enhances the material's resistance to chloride ion corrosion during seawater electrolysis. This heterostructure not only exhibits superior oxygen evolution reaction activity compared to traditional LDH, but also demonstrates excellent structural stability and sustained corrosion resistance at industrial-grade current densities, providing a feasible material solution for advancing the industrial application of seawater electrolysis technology.

[0010] To achieve this objective, the present invention employs the following technical solution:

[0011] In a first aspect, the present invention provides a catalyst for the electro-oxidation of chlorine-containing electrolytes, the catalyst comprising a layered double hydroxide-rare earth basic carbonate heterojunction grown in situ on a nickel substrate, wherein the nickel substrate is nickel foam with a nickel-modified surface.

[0012] This invention innovatively proposes a method from "rejecting Cl" -"Shift to" selective adsorption of OH - The design concept involves introducing rare earth elements to construct a heterojunction structure with layered hydrogen peroxide (LDH) in the form of rare earth basic carbonates. This structure effectively modulates the electron transfer pathway of LDH, regulates the local electronic structure of the LDH metal active center, and enhances the valence state and Lewis acidity of the metal active site. Based on Pearson's hard-soft acid-base (HSAB) theory, this electronic structure modulation strengthens the resistance to OH-. - The selective adsorption capacity of this heterostructure catalyst successfully achieves efficient protection of the anode and synergistic enhancement of catalytic performance under harsh operating conditions. Simultaneously, the oxygen vacancies induced at the interface further optimize the electronic conductivity of the material and expose more highly active sites, jointly promoting the oxygen evolution reaction kinetics. Experimental data show that the electrochemical stability of this heterostructure catalyst in alkaline and simulated seawater electrolytes is more than four times that of ordinary LDH materials, and its oxygen evolution reaction catalytic activity exhibits significant advantages in key indicators such as overpotential and Tafel slope, demonstrating great potential for practical applications.

[0013] Furthermore, compared to transition metal basic carbonates, rare earth elements, due to their unique 4f electron configuration, larger ionic radius, and stable high oxidation state, can introduce significant electronic modulation effects at heterogeneous interfaces. When rare earth basic carbonates form a tight interface with LDH, the charge redistribution and potential bonding at the interface can effectively regulate the electronic state and d-band center position of the metal active center in LDH. This modulation is beneficial for optimizing the catalyst's response to key oxygen-containing intermediates (such as oxygen-containing intermediates) in the OER process. The adsorption energy of CO32- (a rare earth element) lowers the energy barrier of the rate-determining step, thereby enhancing intrinsic catalytic activity. Furthermore, compared to rare earth oxides, alkaline rare earth carbonates benefit from the adsorption energy of CO32- (a rare earth element). 2- / OH - Functional groups can not only more directly enhance the Lewis acidity of the active site to strengthen OH groups. - Selective adsorption allows it to act as an interfacial proton acceptor, synergistically accelerating reaction kinetics and thus simultaneously achieving intrinsic high activity and excellent resistance to chloride ion corrosion.

[0014] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0015] Preferably, the layered double hydroxide includes any one of NiFe-LDH, NiCo-LDH, CoFe-LDH, CoAl-LDH or ZnCo-LDH, with NiFe-LDH being the most preferred.

[0016] Preferably, when the layered double hydroxide is NiFe-LDH, the mass ratio of Ni to Fe is 1:(0.25~0.35), for example, 1:0.25, 1:0.27, 1:0.3, 1:0.32 or 1:0.35, etc.

[0017] Preferably, the rare earth basic carbonate contains any one or a combination of at least two of the rare earth elements selected from lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, or yttrium, and more preferably cerium.

[0018] In this invention, compared to other rare earth elements, Ce has unique properties. 3+ / Ce 4+ The variable valence system and associated oxygen vacancies can synergistically optimize electron transfer and proton transport at the interface, efficiently enhancing the Lewis acidity and OH group of active sites. - Adsorption. At the same time, Ce is the rare earth element with the highest abundance and lowest cost, and it has excellent environmental adaptability and chemical stability, making it the key to achieving the optimal balance between high performance and high practicality.

[0019] Preferably, the rare earth element in the layered double hydroxide-rare earth basic carbonate heterojunction has a mass percentage of 5wt% to 30wt%, such as 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, or 30wt%.

[0020] Preferably, the ratio of the total mass of the two metal elements in the layered double hydroxide to the mass of the rare earth element is (1~8):1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1 or 8:1, etc.

[0021] In this invention, by controlling the content of rare earth elements within the aforementioned range and limiting their mass ratio with the two metal elements in the double hydroxide, it is more beneficial to regulate the crystallization matching degree of the heterostructure interface, ensuring that the two phases form a stable heterostructure with size adaptation and tight coupling at the nanoscale. This optimized composite structure can maximize functional synergy, laying the foundation for efficient interfacial charge transfer and excellent catalytic stability.

[0022] Preferably, the morphology of the layered double hydroxide-rare earth basic carbonate heterojunction is nanoflower-like.

[0023] Preferably, the diameter of the nanoflower-like layered double hydroxide-rare earth basic carbonate heterojunction is 1µm to 3µm, such as 1µm, 1.3µm, 1.5µm, 1.7µm, 2µm, 2.3µm, 2.5µm, 2.8µm or 3µm.

[0024] In a second aspect, the present invention provides a method for preparing a catalyst as described in the first aspect, the method comprising:

[0025] (1) Nickel is deposited on the surface of nickel foam to obtain a nickel substrate;

[0026] (2) Mix the soluble metal salts, soluble rare earth metal salts, corrosion inhibitors and solvents corresponding to the two metal elements in the layered double hydroxide to obtain a precursor solution;

[0027] (3) The nickel substrate described in step (1) is immersed in the precursor solution described in step (2), and the catalyst is obtained after hydrothermal reaction.

[0028] This invention breaks through conventional modification approaches, proposing a one-step synthesis scheme adaptable to various rare earth elements. The ingenuity of this scheme lies in its ability to simultaneously achieve rare earth component doping and heterostructure construction through a simple process, synergistically enhancing the intrinsic chemical stability and interfacial corrosion resistance of the material at both the "composition" and "structure" levels. This strategy, which combines universality, high efficiency, and economy, significantly lowers the barrier to preparation of high-performance, long-life non-precious metal catalysts, demonstrating enormous potential for industrial application.

[0029] In this invention, a catalyst with a heterostructure is directly synthesized by one-step mixing of metal salt precursors followed by a hydrothermal reaction. During this process, basic cerium carbonate acts as a nucleation anchor, guiding and confining the directional growth of NiFe-LDH on its surface, thereby constructing a high-density, strongly coupled heterostructure interface. This structure not only significantly increases the number of active sites and optimizes mass transfer and electron transport pathways, but more importantly, it enhances the resistance to OH groups through interfacial electronic regulation. - Its selective chemisorption capacity leads to superior oxygen evolution catalytic activity and inherently enhanced resistance to chloride ion interference.

[0030] Preferably, the method for depositing nickel in step (1) includes electrodeposition.

[0031] Preferably, the electrodeposition method includes: dissolving a soluble nickel salt and a soluble ammonium salt in water to obtain an electrodeposition solution, and then immersing a nickel foam as a cathode in the electrodeposition solution for electrodeposition.

[0032] It is understandable that deionized water is preferred as the solvent.

[0033] This invention uses nickel foam as the cathode to construct a two-electrode system for cathode electrodeposition. By depositing nickel on the surface of the nickel foam, the nickel layer provides uniform, high-surface-energy nucleation sites, guiding the homogeneous nucleation of the heterojunction. Good initial nucleation promotes the full growth of nanoflowers, creating open pores that are more conducive to mass transfer and bubble desorption. Furthermore, in this way, the heterojunction with nanoflower morphology is more firmly bonded to the substrate, which is more conducive to improving the long-term stability of the catalyst.

[0034] Preferably, the soluble nickel salt includes nickel chloride and / or nickel nitrate.

[0035] Preferably, the soluble ammonium salt includes ammonium chloride.

[0036] In this invention, ammonium chloride plays two roles: first, ammonium ions have a certain pH corrosion inhibition property; second, although chlorine gas bubbles are generated at the anode, they also impact the cathode, promoting the enrichment of elemental Ni on the foamed nickel, ultimately forming coral-like nickel.

[0037] Preferably, the molar ratio of the soluble nickel salt to the soluble ammonium salt is 1:(10~100), for example, 1:10, 1:20, 1:30, 1:50, 1:60, 1:80 or 1:100, etc.

[0038] Preferably, the current density of the electrodeposition is 0.5 A cm⁻¹. -2 ~2A cm -2 More preferably 0.8A cm -2 ~1.5A cm -2 For example, 0.5A cm -2 0.8A cm -2 1A cm -2 1.1A cm -2 1.2A cm -2 1.3A cm -2 1.4A cm -2 1.5A cm -2 Or 2A cm -2 The time is 2 min to 20 min, more preferably 10 min to 15 min, such as 2 min, 5 min, 10 min, 12 min, 15 min or 20 min.

[0039] Preferably, after the electrodeposition is completed, the product is washed and dried sequentially to obtain the nickel substrate.

[0040] Preferably, the soluble metal salts corresponding to the two metal elements in the layered double hydroxide in step (2) are soluble nickel salt and soluble iron salt, wherein the soluble nickel salt contains any one or a combination of at least two of nickel nitrate, nickel chloride or nickel sulfate, and the soluble iron salt contains any one or a combination of at least two of ferric nitrate, ferric chloride or ferric sulfate.

[0041] Preferably, the soluble rare earth salt includes rare earth nitrates or rare earth chlorides.

[0042] Preferably, the corrosion inhibitor in step (2) includes urea.

[0043] Preferably, in step (2), the total molar amount of soluble metal salts corresponding to the two metal elements in the layered double hydroxide, the molar ratio of the rare earth salt and the corrosion inhibitor is (2.5~5):(0.5~1):(10~20), for example 2.5:0.5:10, 3:0.6:12, 3.5:0.7:15, 4:0.8:18 or 5:1:20, etc.

[0044] In this invention, corrosion inhibitors can be used to regulate the morphology of the product. By controlling the amount added within the above-mentioned range, it is more beneficial to generate nanoflower-like heterojunctions.

[0045] Preferably, when the soluble metal salts corresponding to the two metal elements in the layered double hydroxide in step (2) are soluble nickel salt and soluble iron salt, the molar ratio of the soluble iron salt and the soluble nickel salt is 1:(1~3), for example 1:1, 1:1.5, 1:2, 1:2.5, 1:2.8 or 1:3.

[0046] Preferably, the temperature of the hydrothermal reaction in step (3) is 120℃~160℃, for example 120℃, 130℃, 140℃, 150℃ or 160℃, and the time is 6h~24h, for example 6h, 10h, 12h, 15h, 18h, 20h or 24h.

[0047] In this invention, controlling the temperature and time of the hydrothermal reaction within the aforementioned range is more conducive to the synergistic nucleation and orderly growth of heterojunctions. Too low a temperature results in insufficient reaction driving force, making nucleation difficult; too high a temperature leads to an excessively rapid nucleation rate, which, although initially resulting in small particles, easily leads to disordered aggregation or overgrowth, making it difficult to form an ideal heterostructure with size matching and tight coupling. Appropriate temperature and time provide a good growth kinetic balance for the two phases, which is beneficial for constructing high-density, strongly bound heterostructures, laying the foundation for excellent catalytic performance.

[0048] Preferably, after the hydrothermal reaction in step (3) is completed, the obtained solid product is washed and dried sequentially to obtain the catalyst.

[0049] The present invention does not limit the washing and drying methods. For example, the washing liquid used for washing can be any one or at least two of deionized water, ultrapure water or ethanol, and the drying method can be blower drying and / or vacuum drying.

[0050] Thirdly, the present invention provides the application of the catalyst as described in the first aspect in the electro-oxidation anode of seawater.

[0051] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] (1) The catalyst prepared by this invention has a stable structure and abundant active sites, and its performance surpasses that of the reference material. As a seawater electro-oxidation anode, this type of catalyst can achieve long-term stable electro-oxidation at industrial-grade current density and has significantly improved comprehensive performance.

[0054] (2) The preparation method provided by the present invention has both universality and industrialization prospects. Attached Figure Description

[0055] Figure 1 This is a SEM image of the catalyst prepared in Example 1.

[0056] Figure 2 This is a TEM image of the catalyst prepared in Example 1.

[0057] Figure 3 This is a SEM image of the catalyst prepared in Comparative Example 1.

[0058] Figure 4 This is the LSV curve of the catalysts prepared in Examples 1-7.

[0059] Figure 5 The LSV curves are for the catalysts prepared in Example 1 and Comparative Examples 1-5.

[0060] Figure 6 This is a constant voltage stability test graph of the catalysts prepared in Example 1 and Comparative Example 1.

[0061] Figure 7 These are time-of-flight secondary mass spectrometry (TOF-MS) results of the catalysts prepared in Example 1 and Comparative Example 1. Detailed Implementation

[0062] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion.

[0064] Example 1

[0065] This embodiment provides a catalyst for the electro-oxidation of chloride-containing electrolytes, comprising a layered double hydroxide-rare earth basic carbonate heterojunction grown in situ on a nickel substrate, wherein the nickel substrate is nickel foam with a nickel-modified surface. The catalyst is designated NiFe-LDH-Ce(OH)CO3 / NF, wherein the contents of Ni, Fe, and Ce in the NiFe-LDH-Ce(OH)CO3 heterojunction are 29 wt%, 10 wt%, and 25 wt%, respectively. The preparation method is as follows:

[0066] (1) Weigh 0.3 mol of NH4Cl and 10 mmol of NiCl2 into a reaction electrolytic cell, add 100 mL of ultrapure water, use a 1 cm × 1 cm nickel foam as the cathode and a ruthenium-iridium-titanium plate as the anode, and apply a 1.2 A cm -2 A nickel substrate was obtained by electrodeposition with a constant current for 10 min.

[0067] (2) Weigh 2.64 mmol of Ni(NO3)2·6H2O, 1.2 mmol of Fe(NO3)3·9H2O, 0.96 mmol of Ce(NO3)3·6H2O, and 16 mmol of CO(NH2)2 into a 100 mL high-pressure reactor, and add 40 mL of deionized water to form a metal ion precursor solution;

[0068] (3) Immerse the nickel substrate obtained in step (1) into the precursor solution in the high-pressure reactor in step (2), and place it in a drying oven for hydrothermal reaction at 150°C for 12 hours;

[0069] (4) The product obtained in step (3) is washed three times with deionized water and then three times with ethanol, and then dried in a vacuum drying oven for 12 hours.

[0070] Example 2

[0071] This embodiment provides a catalyst for the electro-oxidation of chloride-containing electrolytes, comprising a layered double hydroxide-rare earth basic carbonate heterojunction grown in situ on a nickel substrate, wherein the nickel substrate is nickel foam with a nickel-modified surface. The catalyst is designated NiFe-LDH-Ce(OH)CO3 / NF, wherein the contents of Ni, Fe, and Ce in the NiFe-LDH-Ce(OH)CO3 heterojunction are 28 wt%, 8 wt%, and 5 wt%, respectively. The preparation method is as follows:

[0072] (1) Weigh 0.3 mol of NH4Cl and 3 mmol of NiCl2 into a reaction electrolytic cell, add 100 mL of ultrapure water, use a 1 cm × 1 cm nickel foam as the cathode and a ruthenium-iridium-titanium plate as the anode, and use 0.5 A cm -2 A nickel substrate was obtained by electrodeposition with a constant current for 15 minutes.

[0073] (2) Weigh 3.36 mmol of Ni(NO3)2·6H2O, 1.2 mmol of Fe(NO3)3·9H2O, 0.24 mmol of Ce(NO3)3·6H2O, and 16 mmol of CO(NH2)2 into a 100 mL high-pressure reactor, and add 40 mL of deionized water to form a metal ion precursor solution;

[0074] (3) Immerse the nickel substrate obtained in step (1) into the precursor solution in the high-pressure reactor in step (2), and place it in a drying oven for hydrothermal reaction at 120°C for 24 hours;

[0075] (4) The product obtained in step (3) is washed three times with deionized water and then three times with ethanol, and then dried in a vacuum drying oven for 12 hours.

[0076] Example 3

[0077] This embodiment provides a catalyst for the electro-oxidation of chloride-containing electrolytes, comprising a layered double hydroxide-rare earth basic carbonate heterojunction grown in situ on a nickel substrate, wherein the nickel substrate is nickel foam with a nickel-modified surface. The catalyst is designated NiFe-LDH-Ce(OH)CO3 / NF, wherein the contents of Ni, Fe, and Ce in the NiFe-LDH-Ce(OH)CO3 heterojunction are 23 wt%, 8 wt%, and 30 wt%, respectively. The preparation method is as follows:

[0078] (1) Weigh 0.3 mol of NH4Cl and 30 mmol of NiCl2 into a reaction electrolytic cell, add 100 mL of ultrapure water, use a 1 cm × 1 cm nickel foam as the cathode and a ruthenium-iridium-titanium plate as the anode, and use 2 A cm -2 A nickel substrate was obtained by electrodeposition with a constant current for 12 minutes.

[0079] (2) Weigh 2.16 mmol of Ni(NO3)2·6H2O, 1.2 mmol of Fe(NO3)3·9H2O, 1.44 mmol of Ce(NO3)3·6H2O and 16 mmol of CO(NH2)2 into a 100 mL high-pressure reactor, and add 40 mL of deionized water to form a metal ion precursor solution;

[0080] (3) Immerse the nickel substrate obtained in step (1) into the precursor solution in the high-pressure reactor in step (2) and place it in a drying oven for hydrothermal reaction at 160°C for 6 hours;

[0081] (4) The product obtained in step (3) is washed three times with deionized water and then three times with ethanol, and then dried in a vacuum drying oven for 12 hours.

[0082] Example 4

[0083] The difference between this embodiment and embodiment 1 is that the rare earth basic carbonate is Ho(OH)CO3, and in step (2), Ce(NO3)3·6H2O is replaced with an equimolar amount of Ho(NO3)3·5H2O.

[0084] The remaining preparation methods and parameters are consistent with those in Example 1.

[0085] Example 5

[0086] The difference between this embodiment and Example 1 is that in the NiFe-LDH-Ce(OH)CO3 heterojunction, the contents of Ni, Fe and Ce are 37wt%, 9wt% and 2wt%, respectively; in step (2), 3.48 mmol of Ni(NO3)2·6H2O, 1.2 mmol of Fe(NO3)3·9H2O, 0.12 mmol of Ce(NO3)3·6H2O and 16 mmol of CO(NH2)2 are weighed.

[0087] The remaining preparation methods and parameters are consistent with those in Example 1.

[0088] Example 6

[0089] The difference between this embodiment and embodiment 1 is that the layered double hydroxide is CoFe-LDH; in step (2), Ni(NO3)2·6H2O is replaced with an equimolar amount of Co(NO3)2·6H2O.

[0090] The remaining preparation methods and parameters are consistent with those in Example 1.

[0091] Example 7

[0092] The difference between this embodiment and Embodiment 1 is that the temperature of the hydrothermal reaction in step (3) is 100°C;

[0093] The remaining preparation methods and parameters are consistent with those in Example 1.

[0094] Comparative Example 1

[0095] The difference between this comparative example and Example 1 is that the catalyst does not contain rare earth basic carbonates, denoted as NiFe-LDH / NF, and Ce(NO3)3·6H2O is not added in step (2).

[0096] The remaining preparation methods and parameters are consistent with those in Example 1.

[0097] Comparative Example 2

[0098] The difference between this comparative example and Example 1 is that the nickel substrate in the catalyst is nickel foam, and its surface is not modified with nickel, and step (1) is not performed.

[0099] The remaining preparation methods and parameters are consistent with those in Example 1.

[0100] Comparative Example 3

[0101] The difference between this comparative example and Example 1 is that the catalyst is NiFe-LDH-Co(OH)CO3 / NF, and in step (2), Ce(NO3)3·6H2O is replaced with an equimolar amount of Co(NO3)3·6H2O.

[0102] The remaining preparation methods and parameters are consistent with those in Example 1.

[0103] Comparative Example 4

[0104] The difference between this comparative example and Example 1 is that the catalyst is NiFe-LDH-CeO2 / NF, and the preparation method is as follows:

[0105] Nickel foam was placed in a precursor solution consisting of 1.2 mmol Fe(NO3)3·9H2O, 0.24 mmol Ce(NO3)3·6H2O, and water. Hydrogen peroxide was added dropwise to carry out the reaction. After the reaction was completed, the product NiFe-LDH-CeO2 / NF was obtained by vacuum drying.

[0106] Comparative Example 5

[0107] The difference between this comparative example and Example 1 is that the NiFe-LDH and Ce(OH)CO3 in the catalyst are mechanically mixed independent phases, rather than a heterojunction structure formed by in-situ growth. This catalyst is denoted as NiFe-LDH+Ce(OH)CO3 / NF. In the preparation process, 0.96 mmol of Ce(NO3)3·6H2O and 16 mmol of CO(NH2)2 were weighed into a 100 mL high-pressure reactor, and 40 mL of deionized water was added to form a solution. The nickel substrate obtained in step (1) of Example 1 was immersed in this solution and hydrothermally reacted at 150 °C for 12 h to obtain an intermediate product loaded with Ce(OH)CO3. The obtained Ce(OH)CO3 / NF was used as a substrate and immersed in a precursor solution prepared by dissolving 2.64 mmol of Ni(NO3)2·6H2O, 1.2 mmol of Fe(NO3)3·9H2O and 16 mmol of CO(NH2)2 in 40 mL of deionized water. The solution was then hydrothermally reacted at 150 °C for 12 h in another high-pressure reactor.

[0108] The remaining preparation methods and parameters are consistent with those in Example 1.

[0109] Performance testing

[0110] Cut The catalysts prepared in Examples 1-7 and Comparative Examples 1-5 were used as working electrodes. A three-electrode system was constructed with Hg / HgO as the reference electrode and graphite as the counter electrode. 1M KOH + 0.5M NaCl was used as the electrolyte. The test parameters were set as follows: scan voltage 0~1.2V (vs. Hg / HgO), scan rate 5mV / s. OER electrochemical tests were performed, and the results are as follows. Figure 4 , Figure 5 As shown in Table 1. The overpotential in Table 1 refers to 100 mA cm⁻¹. -2 The overpotential corresponding to the current density.

[0111] Using the catalysts obtained in Example 1 and Comparative Example 1 as working electrodes and a commercial ruthenium-iridium-titanium plate as the counter electrode, a two-electrode system was constructed. A constant current test was conducted at a current of 1 A using 1 M KOH + 0.5 M NaCl as the electrolyte to investigate the stability of the catalysts. The test results are as follows: Figure 6 As shown.

[0112] In addition, SEM and TEM tests were performed on the catalyst obtained in Example 1, and SEM tests were performed on the catalyst obtained in Comparative Example 1. The test results are as follows: Figure 1-3 As shown; and time-of-flight secondary mass spectrometry was performed on the catalysts obtained in Example 1 and Comparative Example 1 to investigate whether the catalysts could react with OH. - or Cl -Selective adsorption, test results are as follows Figure 7 As shown.

[0113] Table 1

[0114]

[0115] The catalyst prepared in Example 1 was subjected to SEM and TEM tests, and the test results are as follows: Figure 1 and Figure 2 As shown in the figure, the catalyst forms a heterojunction containing NiFe-LDH and Ce(OH)CO3. LSV testing was performed on it, and the results are as follows... Figure 4 As shown in Table 1, the overpotential is 208 mV @ 100 mA cm⁻¹ -2 It is superior to commercial RuO2 catalysts; its galvanostatic stability was tested, and the results are as follows: Figure 6 As shown, the results indicate that this catalyst can be applied at 1 A cm⁻¹. -2 It operated stably for over 450 hours at a current density; time-of-flight secondary mass spectrometry was performed on it, and the test results are as follows: Figure 7 As shown, this demonstrates that the NiFe-LDH-Ce(OH)CO3 heterojunction preferentially and selectively adsorbs OH. - Instead of Cl - .

[0116] Similarly, the catalyst prepared in Comparative Example 1 was subjected to SEM and LSV tests. The SEM results are as follows: Figure 3 As shown, its overall morphology is not significantly different from that of the catalyst in Example 1. Analysis of the LSV test results is as follows... Figure 5 As shown, the calculated overpotential is 235mV@100mA cm. -2 . Figure 6 The constant current stability test results show that it can withstand 1A cm -2 It only operated stably for 110 hours at that current density. The results of the time-of-flight secondary mass spectrometry test are as follows: Figure 7 As shown, this demonstrates that the NiFe-LDH catalyst cannot selectively adsorb OH. – Or Cl – This demonstrates that the NiFe-LDH / Ce(OH)CO3 catalyst has greater advantages in catalytic activity and stability compared to the NiFe-LDH catalyst.

[0117] In addition, through Figure 5As can be seen from the comparison of the data of Example 1 and Comparative Examples 2-5 in Table 1, in this invention, the substrate must be modified with nickel, and the composite of layered double hydroxide and rare earth basic carbonate can only exhibit excellent performance when a heterojunction is formed; moreover, rare earth basic carbonate has advantages over transition metal basic carbonate or rare earth oxide.

[0118] The catalysts obtained in Examples 4-7 were subjected to LSV testing, and the test results are as follows: Figure 4 As shown, the calculated overpotentials are 224mV@100mA cm. –2 226mV@100mA cm –2 and 230mV@100mA cm –2 This demonstrates that the method provided by this invention, which involves introducing different types of rare earth elements or different proportions of rare earth salts onto NiFe-LDH to construct heterojunctions, or constructing different types of LDH followed by the introduction of rare earth salts to construct heterojunctions, has universal applicability in enhancing the electro-oxidation activity of seawater. A comparison of data from Example 1 and Example 7 shows that excessively low hydrothermal reaction temperatures are unfavorable for nucleation, leading to a decrease in the performance of the prepared catalyst.

[0119] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A catalyst for the electro-oxidation of chlorine-containing electrolytes, characterized in that, The catalyst comprises a layered double hydroxide-rare earth basic carbonate heterojunction grown in situ on a nickel substrate, wherein the nickel substrate is nickel foam with a nickel-modified surface.

2. The catalyst according to claim 1, characterized in that, The layered double hydroxide includes any one of NiFe-LDH, NiCo-LDH, CoFe-LDH, CoAl-LDH or ZnCo-LDH, preferably NiFe-LDH; Preferably, when the layered double hydroxide is NiFe-LDH, the mass ratio of Ni to Fe is 1:(0.25~0.35).

3. The catalyst according to claim 1 or 2, characterized in that, The rare earth basic carbonates contain rare earth elements including any one or a combination of at least two of lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, or yttrium, preferably cerium; Preferably, the rare earth element accounts for 5 wt% to 30 wt% of the mass percentage in the layered double hydroxide-rare earth basic carbonate heterojunction.

4. The catalyst according to any one of claims 1-3, characterized in that, The ratio of the total mass of the two metal elements in the layered double hydroxide to the mass of the rare earth element is (1~8):

1.

5. The catalyst according to any one of claims 1-4, characterized in that, The morphology of the layered double hydroxide-rare earth basic carbonate heterojunction is nanoflower-like. Preferably, the diameter of the nanoflower-like layered double hydroxide-rare earth basic carbonate heterojunction is 1µm to 3µm.

6. A method for preparing a catalyst according to any one of claims 1-5, characterized in that, The preparation method includes: (1) Nickel is deposited on the surface of nickel foam to obtain a nickel substrate; (2) Mix the soluble metal salts, soluble rare earth metal salts, corrosion inhibitors and solvents corresponding to the two metal elements in the layered double hydroxide to obtain a precursor solution; (3) The nickel substrate described in step (1) is immersed in the precursor solution described in step (2), and the catalyst is obtained after hydrothermal reaction.

7. The preparation method according to claim 6, characterized in that, The method for depositing nickel in step (1) includes electrodeposition; Preferably, the electrodeposition method includes: dissolving a soluble nickel salt and a soluble ammonium salt in water to obtain an electrodeposition solution, and then immersing a nickel foam as a cathode in the electrodeposition solution for electrodeposition. Preferably, the soluble ammonium salt includes ammonium chloride; Preferably, the molar ratio of the soluble nickel salt to the soluble ammonium salt is 1:(10~100); Preferably, the current density of the electrodeposition is 0.5 A cm⁻¹. -2 ~2A cm -2 The time is 2 minutes to 20 minutes; Preferably, after the electrodeposition is completed, the product is washed and dried sequentially to obtain the nickel substrate.

8. The preparation method according to claim 6 or 7, characterized in that, The corrosion inhibitor in step (2) includes urea; Preferably, in step (2), the total molar amount of soluble metal salts corresponding to the two metal elements in the layered double hydroxide, the molar ratio of the rare earth salt and the corrosion inhibitor is (2.5~5):(0.5~1):(10~20).

9. The preparation method according to any one of claims 6-8, characterized in that, The hydrothermal reaction in step (3) is carried out at a temperature of 120℃~160℃ for 6h~24h. Preferably, after the hydrothermal reaction in step (3) is completed, the obtained solid product is washed and dried sequentially to obtain the catalyst.

10. The use of a catalyst as described in any one of claims 1-5 in a seawater electro-oxidation anode.

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