A seawater electrolysis hydrogen production catalyst, a preparation method and application thereof

Abstract

The application provides a seawater electrolysis hydrogen production catalyst and a preparation method and application thereof. The preparation method comprises the following steps: S1: dissolving a nickel salt, an iron salt, a manganese salt and urea in deionized water, uniformly stirring, and obtaining a precursor solution; S2: immersing a pretreated three-dimensional porous conductive substrate in the precursor solution to perform a hydrothermal reaction, and growing a catalyst in situ on the surface of the three-dimensional porous conductive substrate; and S3: after the reaction is completed, taking out the three-dimensional porous conductive substrate with the catalyst, and performing washing and drying to obtain the seawater electrolysis hydrogen production catalyst. The catalyst in the seawater electrolysis hydrogen production catalyst is manganese-doped nickel-iron layered double hydroxide with a three-dimensional hierarchical columnar or rod structure, which greatly increases the specific surface area and the number of active sites of the catalyst, significantly improves the oxygen evolution reaction activity and stability, and exhibits excellent OER performance and super-long running stability in seawater electrolysis hydrogen production.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis for hydrogen production technology, and in particular to a seawater electrolysis hydrogen production catalyst, its preparation method, and its application. Background Technology

[0002] Hydrogen energy, as a clean and efficient secondary energy source, is key to the energy transition. Electrolysis of water using renewable energy is an important pathway to obtain "green hydrogen." However, facing the constraint of freshwater scarcity, using non-potable, low-quality water such as seawater, brackish water, and reclaimed water for hydrogen production will significantly reduce dependence on freshwater resources. Seawater resources are particularly abundant, making direct seawater electrolysis for hydrogen production highly attractive.

[0003] The core challenge in producing hydrogen from low-quality water through electrolysis lies in the high concentration of halide ions, especially chloride ions (Cl-), in the anodic oxygen evolution reaction (OER). - Serious interference from ) Cl - Not only will it compete with OER for electrons and cause chlorine evolution reactions, reducing oxygen production efficiency, but it will also corrode the active sites of the catalyst, leading to rapid catalyst deactivation. Therefore, it is crucial to develop seawater electrolysis OER catalysts that combine high activity, high selectivity, and long-term stability.

[0004] Currently, the modification methods for seawater electrolysis catalysts mainly fall into two categories: one is to construct a protective layer, such as depositing CeO2 nanoparticles on the NiFe-LDH surface or constructing a sulfide / sulfate layer, which inhibits Cl through physical barriers or electrostatic repulsion. - Erosion; another type involves introducing functional components to enhance OH groups. - Adsorb and inhibit Cl - Adsorption, such as loading FeOOH, can improve stability, but these methods often involve complex multi-step synthesis processes or the use of expensive precursors (such as hydrothermal + electrodeposition, redox + electrodeposition, etc.), and the introduced coating layer may increase interfacial resistance, thus contributing little to improving intrinsic catalytic activity.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a seawater electrolysis hydrogen production catalyst, its preparation method, and its application. This catalyst has a large specific surface area and a large number of active sites, which significantly improves the activity and stability of the oxygen evolution reaction.

[0007] This invention provides a method for preparing a catalyst for hydrogen production by seawater electrolysis, comprising the following steps: S1: Dissolve nickel salt, iron salt, manganese salt and urea in deionized water and stir until homogeneous to obtain a precursor solution; S2: The pretreated three-dimensional porous conductive substrate is immersed in the precursor solution for hydrothermal reaction, and the catalyst is grown in situ on the surface of the three-dimensional porous conductive substrate. S3: After the reaction is complete, the three-dimensional porous conductive substrate on which the catalyst has grown is removed, washed and dried to obtain the seawater electrolysis hydrogen production catalyst.

[0008] In this invention, the catalyst grown on the surface of a three-dimensional porous conductive substrate is a manganese-doped nickel-iron layered double hydroxide (NiFeMn-LDH) with a three-dimensional hierarchical columnar or rod-shaped structure. The three-dimensional hierarchical columnar or rod-shaped structure grows vertically or obliquely on the surface of the three-dimensional porous conductive substrate. The diameter of the three-dimensional hierarchical columnar or rod-shaped structure is 50-200 nm, and the length is 0.5-2 μm. Ni, Fe, and Mn elements are uniformly distributed in the three-dimensional hierarchical columnar or rod-shaped structure. More specifically, the columnar or rod-shaped structure in the three-dimensional hierarchical columnar or rod-shaped structure is not a simple solid structure, but a multi-level ordered structure formed by the self-assembly or growth of smaller basic structural units (such as nanosheets or nanoparticles), wherein the primary structure exhibits a distinct columnar or rod-shaped main body (see...). Figure 2 The structure forms the overall three-dimensional framework of the material, providing good mechanical stability and electrical conductivity. The secondary structure is composed of countless tiny, interwoven nanosheets or nanoparticles stacked and assembled.

[0009] The preparation method of this invention uses nickel salts, iron salts, and manganese salts as precursors, and urea as a precipitant and buffer. A catalyst is grown in situ on the surface of a three-dimensional porous conductive substrate under alkaline conditions via a one-step hydrothermal method. Studies have shown that introducing Mn elements into conventional NiFe-LDH using the above-mentioned specific method significantly alters its growth kinetics in the alkaline urea hydrothermal system, inducing its transformation from a traditional two-dimensional nanosheet morphology to a three-dimensional hierarchical columnar or rod-shaped NiFeMn-LDH structure containing vertically or obliquely grown segments. This unique morphological reconstruction not only greatly increases the specific surface area and the number of edge active sites of the catalyst but also facilitates mass transfer and rapid bubble desorption during electrolysis, thereby significantly improving the catalyst's OER performance and stability. Simultaneously, the slow release of hydroxide ions during urea hydrolysis achieves uniform precipitation and N... The uniform co-distribution of i, Fe, and Mn elements in the columnar or rod-shaped structure, with uniform Mn doping optimizing the electronic structure of the material; in addition, urea hydrolysis not only provides hydroxide ions, but the generated CO2 further reacts with hydroxide ions in the solution to generate carbonate ions. Carbonate ions can be directly embedded into the LDH interlayer to balance the charge, and repel the entry of chloride ions during seawater electrolysis. This special structure greatly enhances its corrosion resistance and long-term stability in the seawater environment, making the catalyst exhibit excellent OER performance and ultra-long-term operating stability in alkaline seawater electrolysis hydrogen production, and is particularly suitable for seawater electrolysis hydrogen production.

[0010] In this invention, the molar ratio of Ni, Mn, and Fe in the precursor solution is (0.5-4):(1-2):1, preferably (0.5-2):(0.5-1.5):1, and more preferably 1:(0.5-1.5):1; the total concentration of Ni, Mn, and Fe metal ions in the precursor solution is 0.04-0.2 M, preferably 0.04-0.06 M; and the concentration of urea is 1-5 times the total concentration of metal ions, preferably 1-2 times. In this invention, the three-dimensional porous conductive substrate is nickel foam (NF), copper foam, cobalt foam, metal mesh, or carbon cloth; further, the pore size of the nickel foam is approximately 450-500 μm. Studies have shown that using a three-dimensional porous conductive substrate for in-situ catalyst growth is beneficial for providing a three-dimensional growth framework and nucleation sites, and for guiding stress release and oriented growth, which is conducive to forming the aforementioned specific three-dimensional hierarchical columnar or rod-shaped structures.

[0011] When using foamed metal or metal mesh as a three-dimensional porous conductive substrate, pretreatment is required. Specifically, the pretreatment includes sequential acid washing, water washing, alcohol washing, and drying. Acid washing involves ultrasonic cleaning with a 0.8-1.2 mol / L hydrochloric acid solution for 10-20 min; water washing involves ultrasonic cleaning with deionized water for 10-20 min; alcohol washing involves ultrasonic cleaning with anhydrous ethanol for 10-20 min; and drying is performed at 50-70 ℃ for 20-40 min. This pretreatment dissolves nickel oxide on the surface of the three-dimensional porous conductive substrate, removes organic grease, etches the surface to increase roughness, and improves adhesion.

[0012] In this invention, the temperature of the hydrothermal reaction is 100-140 ℃, preferably 110-130 ℃, and more preferably 120 ℃; the reaction time is 6-18 h, preferably 8-12 h, and more preferably 10 h.

[0013] This invention also provides a seawater electrolysis hydrogen production catalyst, comprising a three-dimensional porous conductive substrate and a catalyst grown on the surface of the three-dimensional porous conductive substrate. The catalyst is a manganese-doped nickel-iron layered double hydroxide with a three-dimensional hierarchical columnar or rod-shaped structure. The three-dimensional hierarchical columnar or rod-shaped structure is grown vertically or obliquely on the surface of the three-dimensional porous conductive substrate. The diameter of the three-dimensional hierarchical columnar or rod-shaped structure is 50-200 nm and the length is 0.5-2 μm. The three elements Ni, Fe, and Mn are uniformly distributed in the three-dimensional hierarchical columnar or rod-shaped structure.

[0014] The present invention also provides a seawater electrolysis hydrogen production catalyst prepared according to the above preparation method, or the application of the above seawater electrolysis hydrogen production catalyst in water electrolysis hydrogen production.

[0015] In this invention, the water used for hydrogen production by water electrolysis can be fresh water, seawater, inland brackish water, reclaimed water, or other low-quality water; in application, the above-mentioned seawater electrolysis hydrogen production catalyst is used as the anode to carry out the oxygen evolution reaction.

[0016] The present invention also provides a seawater electrolysis hydrogen production device, wherein the anode uses the seawater electrolysis hydrogen production catalyst prepared according to the above preparation method or the above-mentioned seawater electrolysis hydrogen production catalyst.

[0017] The implementation of this invention has at least the following advantages: 1. Structural Innovation This invention, for the first time, achieves controllable morphology reconstruction of NiFe-LDH from traditional two-dimensional nanosheets to specific three-dimensional hierarchical columnar or rod-shaped NiFeMn-LDH structures through Mn doping under specific conditions. This structure has the following advantages: 1) Ultra-high specific surface area: The three-dimensional hierarchical columnar or rod-shaped structure greatly increases the specific surface area of ​​the catalyst, exposing more edge and defect active sites.

[0018] 2) Excellent mass transfer performance: The vertically or inclined columnar or rod-shaped structure forms an open three-dimensional channel, which is conducive to the rapid diffusion of electrolytes and the rapid desorption of reaction products (oxygen bubbles), and reduces concentration polarization and bubble shielding effect.

[0019] 3) Enhanced intrinsic activity: Mn doping modulates the electronic structure of Ni and Fe centers, optimizes their adsorption energy for OER reaction intermediates, and improves intrinsic catalytic activity.

[0020] 4) Good corrosion resistance and high stability: During in-situ growth, carbonate ions generated by urea hydrolysis will be embedded into the LDH interlayer to balance the charge. At the same time, the charge repulsion force will repel the entry of chloride ions during electrolysis, which will improve the catalyst's corrosion resistance and long-term stability.

[0021] 2. Excellent performance Thanks to the unique morphology and electronic structure described above, the catalyst of this invention exhibits extremely low overpotential, high current density and ultra-long operating stability in alkaline seawater electrolyte, with performance far superior to undoped NiFe-LDH and other catalysts with complex structures.

[0022] 3. Simple preparation process This invention employs a one-step hydrothermal method to grow catalysts in situ on a three-dimensional porous conductive substrate. The process is simple, the conditions are mild, it does not require precious metals, and it does not require complex subsequent coating or modification steps. The process cost is low, making it very suitable for large-scale production. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 SEM image of Ni2Fe2-LDH / NF; Figure 2 SEM image of Ni2Fe2Mn3-LDH / NF; Figure 3 EDS surface scan elemental distribution map of Ni2Fe2Mn3-LDH / NF; Figure 4 Comparison of XRD patterns of Ni2Fe2Mn3-LDH / NF and Ni2Fe2-LDH / NF; Figure 5 The results show the double-layer capacitance of Ni2Fe2Mn3-LDH / NF and Ni2Fe2-LDH / NF. Figure 6 Linear sweep voltammetry (LSV) curves of NiFe-LDH / NF with different nickel-iron ratios in 1 mol / L KOH + 0.5 mol / L NaCl; Figure 7 NiFe-LDH / NF with different nickel-iron ratios at 100 mA / cm 2 200 mA / cm 2 300 mA / cm 2 Overpotential diagram under current density; Figure 8 Linear sweep voltammetry (LSV) curves of NiFeMn-LDH / NF with different manganese doping amounts in 1 mol / L KOH + 0.5 mol / L NaCl; Figure 9 NiFeMn-LDH / NF with different manganese doping levels at 100 mA / cm 2 200 mA / cm 2 300 mA / cm 2 Overpotential diagram under current density; Figure 10 NiFeMn-LDH / NF with different manganese doping levels at 1 A / cm 2 Stability test curves after 100 hours at current density; Figure 11 Ni2Fe2Mn3-LDH / NF at 1 A / cm2 Stability test curves at current density for 1100 hours. Detailed Implementation

[0025] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, 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.

[0026] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1: Preparation of Ni2Fe2Mn2-LDH / NF The preparation method of the Ni2Fe2Mn2-LDH / NF catalyst for seawater electrolysis hydrogen production in this embodiment includes the following steps: 1. Pretreatment of nickel foam substrate Nickel foam (pore size approximately 450-500 μm) was cut to the desired size (3.5 cm × 4 cm). The nickel foam was then sequentially immersed in 1 mol / L hydrochloric acid solution, deionized water, and anhydrous ethanol, and ultrasonically cleaned for 15 min in each solution to dissolve surface nickel oxide, remove organic grease, and etch the surface to increase roughness and improve adhesion. After ultrasonic cleaning, the foam was removed with tweezers, blotted dry with filter paper, and then dried in a 60 ℃ vacuum drying oven for 30 min for later use.

[0029] 2. Preparation of precursor solution Weigh out 0.2282 g NiCl2·6H2O (approximately 1 mmol NiCl2·6H2O), 0.3878 g Fe(NO3)3·9H2O (approximately 1 mmol Fe(NO3)3·9H2O), 0.2232 ml 50 wt% Mn(NO3)2 solution (approximately 1 mmol Mn(NO3)2), and 0.2522 g urea (approximately 4 mmol urea), respectively, and dissolve them in 60 mL deionized water. Stir magnetically for 30 min until completely dissolved and a clear and transparent solution is formed, thus obtaining the precursor solution.

[0030] 3. Hydrothermal reaction The precursor solution was transferred to a polytetrafluoroethylene (PTFE) hydrothermal reactor liner. A piece of pretreated nickel foam was placed obliquely against the liner wall with tweezers, ensuring it was completely submerged in the precursor solution. The liner was then placed in a stainless steel reactor, which was sealed and placed in a forced-air drying oven. The reactor was reacted at 120 °C for 10 h.

[0031] 4. Post-processing After the reaction was complete, the sample was allowed to cool naturally to room temperature. Then, the nickel foam covered with the green substance was gently removed with tweezers and its surface was gently rinsed with running deionized water to remove loosely adsorbed particles. The sample was then immersed in a beaker containing deionized water and gently agitated for washing, repeating this process 2-3 times. The sample was then dried in a vacuum drying oven at 60 °C for 6 h to obtain the integrated NiFeMn-LDH / nickel foam, denoted as Ni2Fe2Mn2-LDH / NF.

[0032] Example 2: Preparation of Ni2Fe2Mn1-LDH / NF The preparation method of this embodiment is basically the same as that of Example 1, except that in step 2, the amount of 50 wt% Mn(NO3)2 solution is adjusted to 0.1116 mL (about 0.5 mmol Mn(NO3)2) when preparing the precursor solution, and the rest remains unchanged, to obtain an integrated NiFeMn-LDH / foamed nickel, denoted as Ni2Fe2Mn1-LDH / NF.

[0033] Example 3: Ni2Fe2Mn 1.5 Preparation of -LDH / NF The preparation method in this embodiment is basically the same as that in Example 1, except that in step 2, the amount of 50wt% Mn(NO3)2 solution is adjusted to 0.1674 mL (approximately 0.75 mmol Mn(NO3)2) when preparing the precursor solution. All other steps remain unchanged. This yields an integrated NiFeMn-LDH / foamed nickel, denoted as Ni2Fe2Mn. 1.5 -LDH / NF.

[0034] Example 4: Ni2Fe2Mn2.5 Preparation of -LDH / NF The preparation method in this embodiment is basically the same as that in Example 1, except that in step 2, the amount of 50wt% Mn(NO3)2 solution is adjusted to 0.2790 mL (approximately 1.25 mmol Mn(NO3)2) when preparing the precursor solution. All other steps remain unchanged. This yields an integrated NiFeMn-LDH / nickel foam, denoted as Ni2Fe2Mn. 2.5 -LDH / NF.

[0035] Example 5: Preparation of Ni2Fe2Mn3-LDH / NF The preparation method of this embodiment is basically the same as that of Example 1, except that in step 2, the amount of 50wt% Mn(NO3)2 solution is adjusted to 0.3348 mL (about 1.5 mmol Mn(NO3)2) when preparing the precursor solution. The rest remains unchanged, and an integrated NiFeMn-LDH / foamed nickel is obtained, which is denoted as Ni2Fe2Mn3-LDH / NF.

[0036] Comparative Example 1: Preparation of Ni2Fe2-LDH / NF The preparation method of this comparative example is basically the same as that of Example 1, except that Mn(NO3)2 is not added when preparing the precursor solution in step 2. The rest remains unchanged, and NiFe-LDH / foamed nickel is obtained, which is denoted as Ni2Fe2-LDH / NF.

[0037] Comparative Example 2: Preparation of Ni1Fe3-LDH / NF The preparation method of this comparative example is basically the same as that of Example 1, except that in step 2, 0.1141 g NiCl2·6H2O (about 0.5 mmol NiCl2·6H2O) and 0.5817 g Fe(NO3)3·9H2O (about 1.5 mmol Fe(NO3)3·9H2O) were weighed when preparing the precursor solution, and Mn(NO3)2 was not added. The rest remained unchanged, and NiFe-LDH / foamed nickel was obtained, which was denoted as Ni1Fe3-LDH / NF.

[0038] Comparative Example 3: Preparation of Ni3Fe1-LDH / NF The preparation method of this comparative example is basically the same as that of Example 1, except that in step 2, 0.3423 g NiCl2·6H2O (about 1.5 mmol NiCl2·6H2O) and 0.1939 g Fe(NO3)3·9H2O (about 0.5 mmol Fe(NO3)3·9H2O) were weighed when preparing the precursor solution, and Mn(NO3)2 was not added. The rest remained unchanged, and NiFe-LDH / foamed nickel was obtained, which was denoted as Ni3Fe1-LDH / NF.

[0039] Comparative Example 4: Preparation of Ni0Fe4-LDH / NF The preparation method of this comparative example is basically the same as that of Example 1, except that in step 2, 0.7756 g of Fe(NO3)3·9H2O (about 2 mmol Fe(NO3)3·9H2O) was weighed when preparing the precursor solution, and NiCl2·6H2O and Mn(NO3)2 were not added. The rest remained unchanged, and NiFe-LDH / foamed nickel was obtained, which was denoted as Ni0Fe4-LDH / NF.

[0040] Experimental Example 1 The NiFeMn-LDH / nickel foam prepared in each embodiment and the NiFe-LDH / nickel foam prepared in each comparative example were tested as follows: 1. Morphology and structural characterization of catalysts X-ray diffraction (XRD) tests were performed using a Bruker XRD D8 diffractometer (Germany) with Cu Kα radiation (wavelength 1.54178 Å; scan rate 5° / min; operating current 40 mA; operating voltage 40 kV). Scanning electron microscopy (SEM) images were taken using a ZEISS ULTRA55 (accelerating voltage 3 kV).

[0041] The Ni2Fe2Mn3-LDH / NF prepared in Example 5 and the Ni2Fe2-LDH / NF prepared in Comparative Example 1 were characterized by SEM, and the results are as follows: Figure 1 and Figure 2 As shown.

[0042] The results show that the Ni2Fe2-LDH prepared in Comparative Example 1 exhibits a typical flower-like structure of interlaced two-dimensional nanosheets. Figure 1 The Ni2Fe2Mn3-LDH prepared in Example 5 exhibited a significantly different morphology, with a large number of uniform columnar or rod-shaped nanostructures growing vertically or obliquely on the substrate, with a diameter of about 100 nm and a length of about 1 μm, forming a unique three-dimensional hierarchical structure. Figure 2 EDS surface scanning analysis was performed on the Ni2Fe2Mn3-LDH prepared in Example 5, and the results are as follows. Figure 3 As shown, the results indicate that Ni, Fe, and Mn are uniformly distributed in both columnar or rod-shaped structures and substrates, confirming that Mn has been successfully doped into the LDH lattice, and that the morphology reconstruction is an intrinsic change of the overall material, rather than a second phase attached to the surface.

[0043] The XRD patterns of Ni2Fe2Mn3-LDH / NF prepared in Example 5 and Ni2Fe2-LDH / NF prepared in Comparative Example 1 are as follows: Figure 4As shown in the figure; the results show that Ni2Fe2Mn3-LDH still retains the typical structural characteristic peaks of LDH.

[0044] The double-layer capacitance test results of Ni2Fe2Mn3-LDH / NF prepared in Example 5 and Ni2Fe2-LDH / NF prepared in Comparative Example 1 are as follows: Figure 5 As shown, Figure 5 The slope of the fitted curve is the double-layer capacitance of the catalyst, which is proportional to the electrochemical active area of ​​the catalyst. The results show that the electrochemical active area of ​​Ni2Fe2Mn3-LDH is much higher than that of Ni2Fe2-LDH / NF.

[0045] 2. Electrochemical performance testing of catalysts Electrochemical tests were performed using a standard three-electrode system at room temperature without stirring, using a CS310M electrochemical workstation (Wuhan KOST Instrument Co., Ltd.). The catalysts prepared in the examples and comparative examples were used as the working electrode, a graphite rod as the counter electrode, and Hg / HgO (1 M KOH) as the reference electrode. The electrolyte was simulated alkaline seawater of 1 mol / L KOH + 0.5 mol / L NaCl. Electrochemical data were normalized according to the electrode geometry. All potentials were converted to potentials relative to the reversible hydrogen electrode (RHE). Before electrochemical testing, the working electrode was subjected to cyclic voltammetry (CV) at a scan rate of 100 mV / s until a steady state was reached. Polarization curves were measured by linear sweep voltammetry (LSV) at a scan rate of 5 mV / s with 90% iR compensation. Electrochemical impedance spectroscopy (EIS) measurements were performed at an overpotential of 300 mV, with a frequency range of 100 kHz–0.01 Hz and an AC amplitude of 5 mV. Due to water consumption and evaporation, pure water was periodically replenished during stability testing to maintain the water level.

[0046] (1) OER activity test: Figure 6 and Figure 8 The LSV curves are shown for NiFe-LDH / NF with different nickel-iron ratios and NiFeMn-LDH / NF with different manganese doping amounts, respectively. Figure 7 and Figure 9 The overpotential curves are shown for NiFe-LDH / NF with different nickel-iron ratios and NiFeMn-LDH / NF with different manganese doping amounts at different current densities. The results show that the activity is optimal when the nickel-iron molar ratio is 1. Manganese doping further improves the catalytic activity, indicating that Mn doping-induced morphology reconstruction enhances the OER activity of the catalyst.

[0047] (2) Stability test: NiFeMn-LDH / NF with different manganese doping levels at 1 A / cm 2 Long-term stability tests were conducted under constant current density, and the results are as follows: Figure 10 As shown, the results indicate that the NiFeMn-LDH / NF catalyst exhibits almost no overpotential decay within 100 hours.

[0048] To further verify the industrial application potential of NiFeMn-LDH / NF, the performance of Ni2Fe2Mn3-LDH / NF at 1 A / cm² was investigated. 2 A long-term stability test was conducted for 1100 hours at the current density, and the results are as follows: Figure 11 As shown, the results indicate that Ni2Fe2Mn3-LDH / NF exhibits extremely low voltage decay rate and excellent stability.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a catalyst for hydrogen production by seawater electrolysis, characterized in that, Includes the following steps: S1: Dissolve nickel salt, iron salt, manganese salt and urea in deionized water and stir until homogeneous to obtain a precursor solution; S2: The pretreated three-dimensional porous conductive substrate is immersed in the precursor solution for hydrothermal reaction, and the catalyst is grown in situ on the surface of the three-dimensional porous conductive substrate. S3: After the reaction is complete, the three-dimensional porous conductive substrate on which the catalyst has grown is removed, washed and dried to obtain the seawater electrolysis hydrogen production catalyst. Preferably, the catalyst grown on the surface of the three-dimensional porous conductive substrate is a manganese-doped nickel-iron layered double hydroxide with a three-dimensional hierarchical columnar or rod-shaped structure; the three-dimensional hierarchical columnar or rod-shaped structure is grown vertically or obliquely on the surface of the three-dimensional porous conductive substrate; the diameter of the three-dimensional hierarchical columnar or rod-shaped structure is 50-200 nm and the length is 0.5-2 μm.

2. The preparation method according to claim 1, characterized in that, The molar ratio of Ni, Mn, and Fe in the precursor solution is (0.5-4):(1-2):1; the total concentration of Ni, Mn, and Fe metal ions in the precursor solution is 0.04-0.2 M, and the concentration of urea is 1-5 times the total concentration of metal ions.

3. The preparation method according to claim 1, characterized in that, The three-dimensional porous conductive substrate is made of nickel foam, copper foam, cobalt foam, metal mesh, or carbon cloth.

4. The preparation method according to claim 1, characterized in that, The pretreatment includes sequential acid washing, water washing, alcohol washing, and drying. The acid washing involves ultrasonic cleaning with 0.8-1.2 mol / L hydrochloric acid solution for 10-20 min, the water washing involves ultrasonic cleaning with deionized water for 10-20 min, the alcohol washing involves ultrasonic cleaning with anhydrous ethanol for 10-20 min, and the drying temperature is 50-70℃ for 20-40 min.

5. The preparation method according to claim 1, characterized in that, The hydrothermal reaction temperature is 100-140 ℃, and the reaction time is 6-18 h.

6. A catalyst for hydrogen production by seawater electrolysis, characterized in that, It includes a three-dimensional porous conductive substrate and a catalyst grown in situ on the surface of the three-dimensional porous conductive substrate. The catalyst grown on the surface of the three-dimensional porous conductive substrate is a manganese-doped nickel-iron layered double hydroxide with a three-dimensional hierarchical columnar or rod-shaped structure. Preferably, the three-dimensional hierarchical columnar or rod-shaped structure is grown vertically or obliquely on the surface of the three-dimensional porous conductive substrate; the diameter of the three-dimensional hierarchical columnar or rod-shaped structure is 50-200 nm and the length is 0.5-2 μm.

7. The seawater electrolysis hydrogen production catalyst according to claim 6, characterized in that, The three elements Ni, Fe, and Mn exhibit a uniform co-distribution in a three-dimensional hierarchical columnar or rod-shaped structure.

8. The application of the seawater electrolysis hydrogen production catalyst prepared according to any one of claims 1-5 or any one of claims 6-7 in the electrolysis of water to produce hydrogen.

9. The application according to claim 8, characterized in that, The oxygen evolution reaction is carried out using a seawater electrolysis hydrogen production catalyst as the anode.

10. A seawater electrolysis hydrogen production device, characterized in that, The anode is a seawater electrolysis hydrogen production catalyst prepared according to any one of the preparation methods of claims 1-5 or any one of the seawater electrolysis hydrogen production catalysts of claims 6-7.

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