Electrolyzed water catalyst for realizing electrochemical-mechanical dual stabilization based on polydopamine intermediate layer as well as preparation method and application of electrolyzed water catalyst

Abstract

The invention discloses an electrolytic water catalyst for realizing electrochemical-mechanical dual stabilization based on a polydopamine intermediate layer as well as a preparation method and application of the electrolytic water catalyst, and belongs to the technical field of electrocatalyst materials. The electrolyzed water catalyst is of a three-dimensional layered structure; the electrolyzed water catalyst comprises a metal conductive substrate, a polydopamine intermediate layer and a catalyst layer. The synthetic materials are low in price and easy to obtain, the synthetic process is simple, convenient and controllable, and compared with the large-scale preparation problem faced by traditional NiFe-LDH hydrothermal and electro-deposition synthetic methods and the like, the preparation method saves energy and time. The size of the NiFe-LDH nanosheet in the prepared water electrolysis catalyst is obviously reduced, and the structure is beneficial to promoting efficient electron transfer in the electro-catalysis process, inhibiting bubble polymerization and improving mass transfer kinetics.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalyst materials technology, and in particular relates to an electrochemical-mechanical dual stabilization water electrolysis catalyst based on a polydopamine interlayer, its preparation method and application. Background Technology

[0002] Alkaline water electrolysis (AWE) driven by renewable energy is considered an important technology for achieving carbon neutrality and building a sustainable energy future. Nickel-iron layered double hydroxide (NiFe-LDH), as a non-noble metal electrocatalyst for the anodic oxygen evolution reaction (OER) in AWE, has attracted much attention due to its excellent electrocatalytic activity and cost-effectiveness. Despite these advantages, the weak stability of NiFe-LDH at high current densities still restricts its practical application. Its insufficient durability stems from two inherent challenges: (1) excessive surface reconstruction: when a potential is applied, the metal species in NiFe-LDH usually dynamically evolve to a high valence state, forming an active phase and activating the lattice oxygen mechanism (LOM) during the OER process. Although this reconstruction can enhance the activity, it often damages the integrity of the overall material structure, leading to a decrease in stability and performance; (2) poor mechanical stability: under high current density operation, the physical peeling of the catalyst from the substrate under severe gas impact further limits its long-term durability.

[0003] To enhance the stability and activity of the LOM pathway, various strategies for controlling the degree of surface reconstruction have been reported, such as adjusting the electronic structure or coordination environment of metal active sites through defect engineering and elemental doping. However, these strategies still face challenges in maintaining long-term stability under industrial operating conditions. In contrast, methods focusing on mechanical adhesion, such as employing enhanced interlayers, morphology modulation, or bubble regulation, have significantly improved the catalyst's anti-exfoliation stability. Nevertheless, a fundamental trade-off remains: the former fails to adequately address the mechanical failure problem, while the latter cannot simultaneously optimize the LOM pathway through controllable reconstruction. This highlights a key technological gap, and there is an urgent need in the field to develop integrated strategies that combine high LOM mechanism activity with overall stability to meet the requirements of NiFe-LDH catalysts under industrial-grade AWE conditions. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a water electrolysis catalyst with electrochemical-mechanical dual stabilization based on a polydopamine (PDA) interlayer, its preparation method, and its applications. This invention aims to introduce a multifunctional PDA interlayer with excellent adhesion and surface modification into the synthesis of NiFe-LDH catalysts via a simple two-step room-temperature synthesis method, thereby simultaneously solving the challenges of electrode mechanical and electrochemical stability and achieving dual stabilization. Compared to traditional water electrolysis NiFe-LDH catalysts, the PDA interlayer in this invention promotes the generation of lattice oxygen vacancies with enhanced metal-oxygen bonds and highly active metal species, thus activating a more stable and superior LOM pathway in OER. Furthermore, the strong adhesion and interfacial interactions imparted by PDA significantly improve the mechanical and chemical stability of the catalyst. The water electrolysis catalyst provided by this invention offers a feasible and effective guiding scheme for designing advanced OER catalysts that balance operational stability and activity, and is expected to promote the development of efficient and green hydrogen production technology, possessing significant application value.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides an electrochemical-mechanical dual stabilization water electrolysis catalyst based on a polydopamine interlayer, wherein the water electrolysis catalyst has a three-dimensional layered structure and comprises a metal conductive substrate, a polydopamine interlayer, and a catalyst layer.

[0006] Furthermore, the conductive metal substrate is NF (nickel foam); the thickness of the PDA interlayer (polydopamine interlayer) is 100-200 nm; and the size of the NiFe-LDH (nickel-iron layered double hydroxide) nanosheets in the catalyst layer is 50-100 nm.

[0007] Secondly, the present invention provides a method for preparing the above-mentioned electrochemical-mechanical dual stabilization water electrolysis catalyst based on a polydopamine interlayer, comprising the following steps: using nickel foam as a three-dimensional conductive substrate, firstly depositing a PDA interlayer on the nickel foam through the self-polymerization reaction of dopamine hydrochloride in an alkaline environment, and then performing an etching reaction in a homogeneous solution containing ferric nitrate and sodium thiosulfate to form a catalyst layer, thereby preparing the electrochemical-mechanical dual stabilization water electrolysis catalyst based on a polydopamine interlayer.

[0008] Further, the specific preparation method includes the following steps: dissolving dopamine hydrochloride in Tris-HCl buffer, immersing the pretreated nickel foam in Tris-HCl buffer containing dopamine hydrochloride, performing a first stirring reaction, removing the nickel foam after the first stirring reaction, washing it, and vacuum drying it at 25 °C to obtain PDA / NF (polydopamine / nickel foam); immersing the PDA / NF in a homogeneous solution containing ferric nitrate and sodium thiosulfate, performing a second stirring reaction, removing the nickel foam after the second stirring reaction, washing it, and drying it under a nitrogen atmosphere to obtain the electrochemical-mechanical dual stabilization water electrolysis catalyst based on the polydopamine interlayer.

[0009] Further, the concentration of the Tris-HCl buffer is 0.1-0.5 M, and the pH is 8.5-8.8; the concentration of dopamine hydrochloride in the Tris-HCl buffer is 0.5-2 mg / mL. -1 .

[0010] Furthermore, the concentrations of ferric nitrate and sodium thiosulfate in the homogeneous solution are 0.086 mol / L and 0.02 mol / L, respectively.

[0011] Furthermore, the initial stirring reaction was carried out at room temperature, with a stirring speed of 350 rpm and a reaction time of 6 hours. The vacuum drying time is 12 hours; The specific operation of the secondary stirring reaction is as follows: shake at 200 rpm for 5 minutes in a shaker at room temperature; The drying process under nitrogen atmosphere was carried out at room temperature for 4 hours.

[0012] Furthermore, a co-solvent was added when the dopamine hydrochloride was dissolved in the Tris-HCl buffer; the volume ratio of the co-solvent to the Tris-HCl buffer was 1:1; the co-solvent was selected from anhydrous ethanol.

[0013] Thirdly, the present invention provides an application of the above-mentioned electrochemical-mechanical dual stabilization of water electrolysis catalyst based on polydopamine intermediate layer in a three-electrode electrolyzer.

[0014] Compared with catalysts without a PDA interlayer and commercial catalysts, the proposed water electrolysis catalyst exhibits lower overpotential, faster reaction kinetics, and higher stability.

[0015] When the aforementioned water electrolysis catalyst is applied in a three-electrode electrolysis cell, it is carried out under industrial conditions containing a high current density range, with the maximum current density reaching 1.0 A cm⁻¹. -2 above.

[0016] Fourthly, this invention provides an application of the above-mentioned electrochemically-mechanically stabilized water electrolysis catalyst based on a polydopamine interlayer in an AEMWE (anion exchange membrane electrolyzer). Using the aforementioned water electrolysis catalyst as the anode in the water electrolysis reaction, the AEMWE assembled with this catalyst exhibits superior performance compared to AEMWEs assembled with catalysts without an interlayer and with commercially available catalysts.

[0017] When the water electrolysis catalyst is applied in AEMWE, it is carried out under industrial conditions with a high current density range, wherein the maximum current density reaches 1.0 A cm⁻¹. -2 above.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects: (1) The synthetic material of the present invention is inexpensive and readily available, which reduces the cost of precious metal catalytic electrodes commonly used in AEMWE. The synthesis process is simple and controllable. Compared with other non-precious metal catalyst synthesis methods in OER, it avoids high temperature and high pressure conditions and electrodeposition process that easily generates a large amount of difficult-to-treat wastewater. This preparation method is more green, energy-saving and time-saving. (2) The size of NiFe-LDH nanosheet flowers in the water electrolysis catalyst prepared by the present invention is significantly reduced. This micro-nano structure leads to a rich high curvature catalytic surface, which is beneficial to enhance the local electric field, promote efficient electron transfer during electrocatalysis, and improve mass transfer kinetics. (3) The introduction of the PDA interlayer enables electronic interaction between the PDA layer and active metal atoms, promoting the formation of lattice oxygen with enhanced metal-oxygen bonds and highly active nickel species, thereby facilitating a more stable and efficient LOM pathway. Experimental results demonstrate that, compared to NiFe-LDH catalysts without an interlayer and commercial catalysts (RuO2 and IrO2), this catalyst exhibits the best OER performance and the fastest reaction kinetics, and possesses the highest intrinsic and mass activity.

[0019] (4) The PDA interlayer improves surface wettability, which is an important factor affecting the gas-liquid-solid three-phase interface and mass transfer kinetics. Contact angle measurements show that S-NiFe@PDA has superhydrophilicity (contact angle ~0°), which is significantly improved compared to catalysts without an interlayer (~23.2°). This enhanced hydrophilicity is attributed to the abundant hydrophilic groups (such as -OH, -NH2) in PDA, which can promote electrolyte permeation, inhibit bubble aggregation, and accelerate bubble release.

[0020] (5) This invention investigated the stability of the catalyst in a laboratory three-electrode system. The introduction of the PDA interlayer provided strong adhesion and interfacial interactions, effectively suppressing catalyst stripping at high current densities and significantly improving long-term durability. For the three-electrode reaction, the catalyst exhibited excellent operational stability, with its linear sweep voltammetry curve showing negligible changes after 5000 cycles and remaining stable at 500 mA cm⁻¹. -2 It operated continuously for over 1100 hours under these conditions at 1000 mA cm⁻¹ -2 It operates for over 500 hours under certain conditions. Furthermore, compared to NiFe catalysts without an intermediate layer, this catalyst exhibits minimal active metal leaching after the OER reaction, and its surface layered structure remains well-preserved, indicating good durability in practical applications.

[0021] (6) This invention also investigated the stability of the catalyst in the AEMWE system under industrial conditions. When integrated into AEMWE, the catalyst maintained a stability of 1.0 A cm⁻¹ at room temperature. -2 The catalyst achieved stable operation for over 2100 hours at the specified current density. These findings demonstrate its considerable potential for industrial applications. They provide valuable insights into designing OER electrocatalysts that combine high activity with industrial durability, which will drive the development of efficient water electrolysis systems. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 In Example 1, a is a schematic diagram of the process for preparing the water electrolysis catalyst, and in Comparative Example 1, b is a schematic diagram of the process for preparing the water electrolysis catalyst. Figure 2 In Figure a, SEM image (scale 200 nm) of S-NiFe@PDA / NF prepared in Example 1 is shown, and SEM image (scale 500 nm) of S-NiFe / NF prepared in Comparative Example 1 is shown. Figure 3 In Figure a, TEM image (scale 100 nm) of S-NiFe@PDA / NF prepared in Example 1 is shown, and in Figure b, TEM image (scale 200 nm) of S-NiFe / NF prepared in Comparative Example 1 is shown. Figure 4 High-resolution transmission electron microscopy image (scale 5 nm) of S-NiFe@PDA / NF prepared in Example 1; Figure 5 In Figure a, the AFM image of S-NiFe@PDA / NF prepared in Example 1 is shown (maximum size 180 nm), and in Figure b, the AFM image of S-NiFe / NF prepared in Comparative Example 1 is shown (maximum size 900 nm). Figure 6 XRD patterns of S-NiFe@PDA / NF prepared in Example 1 and S-NiFe / NF prepared in Comparative Example 1; Figure 7 ATR-FTIR spectra of S-NiFe@PDA / NF prepared in Example 1 and S-NiFe / NF prepared in Comparative Example 1; Figure 8 Raman plots of S-NiFe@PDA / NF prepared in Example 1 and S-NiFe / NF prepared in Comparative Example 1; Figure 9 The LSV performance diagrams are for the water electrolysis catalysts prepared in Examples 1-3. Figure 10 LSV performance graphs of the water electrolysis catalysts prepared in Example 1 and Comparative Examples 1, 2 and 3; Figure 11 Tafel slope curves of the water electrolysis catalysts prepared in Example 1 and Comparative Examples 1, 2 and 3. Figure 12 Nyquist plots of the water electrolysis catalysts prepared in Example 1 and Comparative Examples 1, 2 and 3; Figure 13 TOF curves of the water electrolysis catalysts prepared in Example 1 and Comparative Example 1; Figure 14 The mass activity curves of the water electrolysis catalysts prepared in Example 1 and Comparative Example 1 are shown. Figure 15 Chronovoltaic stability test results (current density 0.5 A cm⁻¹) of the water electrolysis catalysts prepared in Example 1 and Comparative Example 1. -2 ); Figure 16 The chronovoltaic stability test curve for the water electrolysis catalyst prepared in Example 1 (current density 1.0 Acm) is shown. -2 ); Figure 17 A comparison of the performance of the water electrolysis catalyst prepared in Example 1 of this invention with data from existing literature (current density 0.5 A cm⁻¹). -2 ); Figure 18 A comparison of the performance of the water electrolysis catalyst prepared in Example 1 of this invention with data from existing literature (current density 1.0 A cm⁻¹). -2 ); Figure 19 Performance graphs of AEMWE for the water electrolysis catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2; Figure 20 Chrono-voltage stability test results of the AEMWE assembly containing the water electrolysis catalyst prepared in Example 1 (current density 1.0 A cm⁻¹). -2 ); Figure 21 In Figure a, S-NiFe@PDA / NF prepared in Example 1 and S-NiFe / NF prepared in Comparative Example 1 are photographs after ultrasonic treatment in deionized water; in Figure b, the concentrations of Ni and Fe elements in the aqueous solution after ultrasonication for 30 min are shown. Detailed Implementation

[0024] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0025] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0026] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0027] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0028] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0029] The room temperature in this invention refers to 25±2℃.

[0030] Unless otherwise specified, all materials used in this invention are commercially available products.

[0031] This invention provides a water electrolysis catalyst with electrochemical-mechanical dual stabilization based on a polydopamine interlayer, namely a high-efficiency water electrolysis NiFe-LDH catalyst containing a polydopamine interlayer. Using nickel foam as a three-dimensional conductive substrate, a polydopamine layer is first deposited on the nickel foam through the self-polymerization reaction of dopamine hydrochloride in an alkaline environment. Subsequently, an etching reaction is carried out in a homogeneous solution containing ferric nitrate and sodium thiosulfate. After cleaning and drying, a high-efficiency water electrolysis NiFe-LDH catalyst composite material containing a polydopamine interlayer is obtained. This catalyst is S-NiFe@PDA / NF, comprising a metal conductive substrate, a polydopamine interlayer, and a catalyst layer, exhibiting a three-dimensional layered structure.

[0032] Example 1: A method for preparing an electrochemically-mechanically stabilized water electrolysis catalyst based on a polydopamine interlayer. (1) Surface pretreatment of nickel foam: (1-1) Cut the nickel foam to the specified size (1.5 cm). Immerse 1 cm of the sample in 2 M hydrochloric acid and sonicate for 15 min. (1-2) After being sonicated with hydrochloric acid, the foamed nickel was rinsed with deionized water and then immersed in anhydrous ethanol and sonicated for 15 minutes. (1-3) After ultrasonication with anhydrous ethanol, the foamed nickel was rinsed with deionized water and then immersed in deionized water for ultrasonication for 15 min. Afterwards, it was taken out, washed, and placed in a vacuum dryer at 25 °C for the next step of use.

[0033] (2) Preparation of polydopamine interlayer: (2-1) Weigh 6.055 g of tris(hydroxymethyl)aminomethane and dissolve it in 400 mL of deionized water. After cooling, slowly adjust the pH to 8.6 with hydrochloric acid (10 M). Finally, make up the volume to 500 mL with deionized water to prepare a 0.1 M Tris-HCl buffer solution. (2-2) Weigh 100 mg of dopamine hydrochloride and dissolve it in 50 mL of 0.1 M Tris-HCl buffer obtained in step (2-1). Immerse the pretreated nickel foam in step (1) into Tris-HCl buffer containing dopamine hydrochloride and stir at room temperature (350 rpm, 6 h). (2-3) Take out the sample obtained in step (2-2), wash it three times in sequence with deionized water, anhydrous ethanol and deionized water respectively, and then place it at 25 ℃ and vacuum dry for 12 h to obtain polydopamine / nickel foam, denoted as PDA / NF. (3) Preparation of NiFe-LDH catalyst layer: (3-1) Weigh 0.2612 g of ferric nitrate nonahydrate and 0.0373 g of sodium thiosulfate pentahydrate, dissolve them in 7.5 mL of deionized water, and stir continuously to prepare a homogeneous solution; (3-2) Immerse the PDA / NF sample obtained in step (2) into the homogeneous solution in step (3-1), then place the container in a shaker and shake at 200 rpm for 5 min at room temperature. Remove the sample from the homogeneous solution for later use. (3-3) The sample obtained in step (3-2) was washed three times in sequence with deionized water, anhydrous ethanol and deionized water respectively, and then dried under nitrogen atmosphere (room temperature, 4 h) to obtain an electrochemical-mechanical dual stabilization water electrolysis catalyst based on polydopamine interlayer, denoted as S-NiFe@PDA / NF, wherein the thickness of polydopamine interlayer is 100-200 nm and the size of nanosheets in catalyst layer is 50-100 nm.

[0034] Figure 1 In Figure 'a', it is a schematic diagram of the process for preparing the water electrolysis catalyst in Example 1; Example 2: A method for preparing an electrochemically-mechanically stabilized water electrolysis catalyst based on a polydopamine interlayer. (1) Surface pretreatment of nickel foam: (1-1) Cut the nickel foam to the specified size (1.5 cm). Immerse 1 cm of the sample in 2 M hydrochloric acid and sonicate for 15 min. (1-2) After being sonicated with hydrochloric acid, the foamed nickel was rinsed with deionized water and then immersed in anhydrous ethanol and sonicated for 15 minutes. (1-3) After ultrasonication with anhydrous ethanol, the foamed nickel was rinsed with deionized water and then immersed in deionized water for ultrasonication for 15 min. Afterwards, it was taken out, washed, and placed in vacuum drying at 25 ℃ for the next step of use. (2) Preparation of polydopamine interlayer: (2-1) Weigh 6.055 g of tris(hydroxymethyl)aminomethane and dissolve it in 400 mL of deionized water. After cooling, slowly adjust the pH to 8.6 with hydrochloric acid (10 M). Finally, make up the volume to 500 mL with deionized water to prepare a 0.1 M Tris-HCl buffer solution.

[0035] (2-2) Weigh 25 mg of dopamine hydrochloride and dissolve it in 50 mL of 0.1 M Tris-HCl buffer obtained in step (2-1). Immerse the pretreated nickel foam in step (1) in Tris-HCl buffer containing dopamine hydrochloride and stir at room temperature (350 rpm, 6 h). (2-3) Take out the sample obtained in step (2-2) and wash it three times in sequence with deionized water, anhydrous ethanol and deionized water respectively. Then place it at 25 ℃ and vacuum dry for 12 h to obtain PDA / NF.

[0036] (3) Preparation of NiFe-LDH catalyst layer: (3-1) Weigh 0.2612 g of ferric nitrate nonahydrate and 0.0373 g of sodium thiosulfate pentahydrate, dissolve them in 7.5 mL of deionized water, and stir continuously to prepare a homogeneous solution; (3-2) Immerse the PDA / NF sample obtained in step (2) into the homogeneous solution in step (3-1), then place the container in a shaker and shake at 200 rpm for 5 min at room temperature. Remove the sample from the homogeneous solution for later use. (3-3) The sample obtained in step (3-2) was washed three times each with deionized water, anhydrous ethanol, and deionized water, and then dried under a nitrogen atmosphere (room temperature, 4 h) to obtain the S-NiFe@PDA / NF sample. The thickness of the polydopamine interlayer was 100-200 nm, and the size of the nanosheets in the catalyst layer was 50-100 nm.

[0037] Example 3: A method for preparing an electrochemically-mechanically stabilized water electrolysis catalyst based on a polydopamine interlayer. (1) Surface pretreatment of nickel foam: (1-1) Cut the nickel foam to the specified size (1.5 cm). Immerse 1 cm of the sample in 2 M hydrochloric acid and sonicate for 15 min. (1-2) After being sonicated with hydrochloric acid, the foamed nickel was rinsed with deionized water and then immersed in anhydrous ethanol and sonicated for 15 minutes. (1-3) After ultrasonication with anhydrous ethanol, the foamed nickel was rinsed with deionized water and then immersed in deionized water for ultrasonication for 15 min. Afterwards, it was taken out, washed, and placed in vacuum drying at 25 ℃ for the next step of use. (2) Preparation of polydopamine interlayer: (2-1) Weigh 6.055 g of tris(hydroxymethyl)aminomethane and dissolve it in 400 mL of deionized water. After cooling, slowly adjust the pH to 8.6 with hydrochloric acid (10 M). Finally, make up the volume to 500 mL with deionized water to prepare a 0.1 M Tris-HCl buffer solution. (2-2) Weigh 25 mg of dopamine hydrochloride and dissolve it in 25 mL of 0.1 M Tris-HCl buffer obtained in step (2-1). Add 25 mL of anhydrous ethanol as a co-solvent. Immerse the pretreated nickel foam in step (1) in Tris-HCl buffer containing dopamine hydrochloride and ethanol and stir at room temperature (350 rpm, 6 h). (2-3) Take out the sample obtained in step (2-2) and wash it three times with deionized water, anhydrous ethanol and deionized water respectively. Then, place it in a vacuum dryer at 25 °C for 12 h to obtain the PDA / NF sample. (3) Preparation of NiFe-LDH catalyst layer: (3-1) Weigh 0.2612 g of ferric nitrate nonahydrate and 0.0373 g of sodium thiosulfate pentahydrate, dissolve them in 7.5 mL of deionized water, and stir continuously to prepare a homogeneous solution; (3-2) Immerse the PDA / NF sample obtained in step (2) into the homogeneous solution in step (3-1), then place the container in a shaker and shake at 200 rpm for 5 min at room temperature. Remove the sample from the homogeneous solution for later use. (3-3) The sample obtained in step (3-2) was washed three times each with deionized water, anhydrous ethanol, and deionized water, and then dried under a nitrogen atmosphere (room temperature, 4 h) to obtain the S-NiFe@PDA / NF sample. The thickness of the polydopamine interlayer was 100-200 nm, and the size of the nanosheets in the catalyst layer was 50-100 nm.

[0038] Comparative Example 1 The difference between this comparative example and Example 1 is that it does not include the step of preparing the polydopamine interlayer. The specific preparation method is as follows: (1) Surface pretreatment of nickel foam: Same as in Example 1; (2) Preparation of NiFe-LDH catalyst layer: (2-1) Weigh 0.2612 g of ferric nitrate nonahydrate and 0.0373 g of sodium thiosulfate pentahydrate, dissolve them in 7.5 mL of deionized water, and stir continuously to prepare a homogeneous solution; (2-2) Immerse the pretreated nickel foam from step (1) into the homogeneous solution obtained in step (2-1), then place the container in a shaker and shake at 200 rpm for 5 min at room temperature. Remove the sample from the homogeneous solution for later use. (2-3) The sample obtained in step (3-2) was washed three times with deionized water, anhydrous ethanol and deionized water respectively, and then dried under nitrogen atmosphere (room temperature, 4 h) to prepare the water electrolysis catalyst, denoted as S-NiFe / NF.

[0039] Figure 1 Figure b is a schematic diagram of the process for preparing the water electrolysis catalyst in Comparative Example 1.

[0040] The S-NiFe@PDA / NF prepared in Example 1 and the S-NiFe / NF prepared in Comparative Example 1 were placed in deionized water and subjected to ultrasonic treatment (150 W). The samples were photographed at 0 min, 15 min and 30 min, respectively. After 30 min of ultrasonic treatment, the concentrations of Ni and Fe elements in the aqueous solution were measured. Figure 21 In Figure a, S-NiFe@PDA / NF prepared in Example 1 and S-NiFe / NF prepared in Comparative Example 1 are photographs after ultrasonic treatment in deionized water; in Figure b, the concentrations of Ni and Fe elements in the aqueous solution after ultrasonication for 30 min are shown.

[0041] Comparative Example 2 (1) Surface pretreatment of nickel foam: (1-1) Cut the nickel foam to the specified size (1.5 cm). Immerse 1 cm of the sample in 2 M hydrochloric acid and sonicate for 15 min. (1-2) After being sonicated with hydrochloric acid, the foamed nickel was rinsed with deionized water and then immersed in anhydrous ethanol and sonicated for 15 minutes. (1-3) After ultrasonication with anhydrous ethanol, the foamed nickel was rinsed with deionized water and then immersed in deionized water for ultrasonication for 15 min. Afterwards, it was taken out, washed, and placed in vacuum drying at 25 ℃ for the next step of use. (2) Support of commercial RuO2 catalyst: (2-1) Weigh 10 mg of commercial RuO2 powder and disperse it in a mixed solution of 40 uL Nafion (perfluorosulfonic acid polymer solution, Macklin), 950 uL anhydrous ethanol and 950 uL isopropanol, and then sonicate for 2 h to form a uniform suspension. (2-2) The uniform suspension containing the commercial RuO2 catalyst obtained in step (2-1) was dropped onto the pretreated nickel foam surface obtained in step (1), and the weight change before and after was controlled to be 1.0 mg cm⁻¹. -2 The sample was then washed three times each with deionized water, anhydrous ethanol, and deionized water, and dried in air for 12 hours to obtain the RuO2 / NF sample.

[0042] Comparative Example 3 The difference between Comparative Example 3 and Comparative Example 2 is that the commercial catalyst RuO2 powder of equal mass (10 mg) was replaced with commercial catalyst IrO2 powder, thus obtaining the IrO2 / NF sample.

[0043] Experimental Example 1 The microstructure of S-NiFe@PDA / NF prepared in Example 1 and S-NiFe / NF prepared in Comparative Example 1 was characterized by SEM (scanning electron microscopy). Figure 2 Image a is a SEM image (scale 200 nm) of S-NiFe@PDA / NF prepared in Example 1. Figure 2 In Figure b, the SEM image (scale 500 nm) of S-NiFe / NF prepared in Comparative Example 1 is shown.

[0044] Depend on Figure 2 As can be seen, compared with Comparative Example 1, the S-NiFe@PDA / NF prepared in Example 1 of the present invention has smaller NiFe-LDH nanosheets that grow uniformly due to the interaction between the PDA layer and the catalyst layer. This is beneficial to promote efficient electron transfer during electrocatalysis, inhibit bubble polymerization, and improve mass transfer kinetics.

[0045] Experimental Example 2 The S-NiFe@PDA / NF prepared in Example 1 and the S-NiFe / NF prepared in Comparative Example 1 were characterized by TEM (transmission electron microscopy). Figure 3 Image a is a TEM image (scale 100 nm) of S-NiFe@PDA / NF prepared in Example 1. Figure 3 b is a TEM image (scale 200 nm) of S-NiFe / NF prepared in Comparative Example 1. Figure 3 As can be seen from the diagram, the S-NiFe@PDA / NF structure prepared in Example 1 of this invention exhibits an integrated architecture between the nanosheets and the PDA, with the nanosheets growing on the PDA layer. Conversely, the S-NiFe / NF structure prepared in Comparative Example 1 of this invention displays a distinct nanosheet stacking structure, attributed to the larger size of its grown nanosheets.

[0046] Experimental Example 3 The S-NiFe@PDA / NF prepared in Example 1 was characterized by HRTEM (high resolution transmission electron microscopy). Figure 4 High-resolution transmission electron microscopy image (scale 5 nm) of S-NiFe@PDA / NF prepared in Example 1.

[0047] Depend on Figure 4 The observed lattice fringes have interlayer spacings of 0.264 and 0.444 nm, corresponding to the (101) and (006) crystal planes of the NiFe-LDH phase in S-NiFe@PDA / NF, confirming that the crystal structure is preserved on the PDA layer. Selected area electron diffraction (SAED) patterns show clear diffraction rings, further verifying its crystal properties.

[0048] Test Example 4 The S-NiFe@PDA / NF prepared in Example 1 and the S-NiFe / NF prepared in Comparative Example 1 were characterized by AFM (atomic force microscopy). Figure 5 In Figure a, the image is the AFM pattern (maximum size 180 nm) of S-NiFe@PDA / NF prepared in Example 1. Figure 5 b is the AFM pattern (maximum size 900 nm) of S-NiFe / NF prepared in Comparative Example 1. Figure 5 As can be seen from the data, the size of the S-NiFe@PDA / NF nanosheets prepared in Example 1 of this invention is significantly smaller than that of the S-NiFe / NF prepared in Comparative Example 1 of this invention.

[0049] Experimental Example 5 The S-NiFe@PDA / NF prepared in Example 1 and the S-NiFe / NF prepared in Comparative Example 1 were characterized by XRD (X-ray diffraction). Figure 6 The XRD patterns are of S-NiFe@PDA / NF prepared in Example 1 and S-NiFe / NF prepared in Comparative Example 1.

[0050] Depend on Figure 6 It can be seen that the diffraction patterns of the electrocatalysts in Example 1 and Comparative Example 1 are highly consistent, confirming that the introduction of the PDA intermediate layer did not change the NiFe-LDH crystal structure.

[0051] Experimental Example 6 The S-NiFe@PDA / NF prepared in Example 1 and the S-NiFe / NF prepared in Comparative Example 1 were characterized by ATR-FTIR (attenuated total reflection Fourier transform infrared spectroscopy). Figure 7 ATR-FTIR spectra of S-NiFe@PDA / NF prepared in Example 1 and S-NiFe / NF prepared in Comparative Example 1. Figure 7 It can be seen that the electrocatalysts prepared in Example 1 and Comparative Example 1 both exhibit characteristic peaks of a layered double hydroxide structure. In addition, the ATR-FTIR spectrum of Example 1 shows vibrational peaks corresponding to characteristic groups in the PDA, confirming the successful introduction of the PDA intermediate layer.

[0052] Experimental Example 7 The S-NiFe@PDA / NF prepared in Example 1 and the S-NiFe / NF prepared in Comparative Example 1 were characterized by Raman scattering. Figure 8 Raman spectroscopy plots of S-NiFe@PDA / NF prepared in Example 1 and S-NiFe / NF prepared in Comparative Example 1.

[0053] Depend on Figure 8 It can be seen that the electrocatalysts prepared in Example 1 and Comparative Example 1 of this invention both have a range of ~435 cm⁻¹. -1and 536 cm -1 Peak values ​​are observed at these locations, corresponding to Ni. 2+ -OH and Ni 2+ -O of e g With a 1g Extensive vibration, simultaneously exhibiting a diameter of ~257 cm. -1 ~345 cm -1 and ~649 cm -1 The characteristic peaks are attributed to FeOOH. No significant PDA peaks were observed in the Raman spectrum, indicating that their presence did not disrupt the MO coordination structure. These results confirm the successful synthesis of the electrocatalyst prepared in Example 1 of this invention, which possesses a complete NiFe-LDH phase and an embedded PDA interlayer.

[0054] Application Example 1 The OER activity of the electrocatalysts prepared in Examples 1-3 and Comparative Examples 1-3 was evaluated in a three-electrode electrolyzer system: The electrochemical workstation used was a DH7003A (Donghua Analytical Instruments). The test system was a typical three-electrode system, and the working electrode was the electrocatalyst prepared in Examples 1-3 and Comparative Examples 1-3 (effective geometric area of ​​1.0 × 1.0 cm²). 2 A platinum mesh was used as the counter electrode, and Hg / HgO was used as the reference electrode. The electrolyte was a 1.0 M KOH solution. Before each test, the solution was purged with N2 for 10 min to eliminate interference from residual oxygen in the solution. All electrochemical tests were performed at room temperature. Linear sweep voltammetry (LSV) was used, with the scan potential range set from 0 to 1.7 V (relative to Hg / HgO) and the scan rate at 5 mV s. -1 All LSV data were obtained based on ohmic loss compensation (iR compensation) of the electrolyte resistance (R) measured by electrochemical impedance spectroscopy (EIS) at open circuit potential (OCP). LSV performance diagrams of the electrocatalysts synthesized in Examples 1-3 and Comparative Examples 1-3 were obtained, and the test results are as follows: Figure 9-10 As shown, Figure 9 The LSV performance diagrams are for the water electrolysis catalysts prepared in Examples 1-3. Figure 10 The LSV performance graphs are for the water electrolysis catalysts prepared in Example 1 and Comparative Examples 1, 2, and 3. Figure 9-10 As can be seen from the above, the electrocatalyst prepared in Example 1 of this invention has the highest OER activity.

[0055] Furthermore, Tafel slope curves of the water-splitting catalysts prepared in Example 1 and Comparative Examples 1, 2, and 3 were obtained using LSV curve data. Additionally, Nyquist curves were obtained using EIS (electrochemical impedance spectroscopy). EIS measurements were performed in the frequency range of 0.1 to 100 kHz with an amplitude of 10 mV. The results are as follows... Figure 11-12 As shown, Figure 11 Tafel slope curves of the water electrolysis catalysts prepared in Example 1 and Comparative Examples 1, 2 and 3. Figure 12 The Nyquist plots are for the water electrolysis catalysts prepared in Example 1 and Comparative Examples 1, 2, and 3. Figure 11 and 12 It can be seen that: Example 1 of the present invention exhibits the fastest reaction kinetics, with a Tafel slope of 48.5 mV dec. -1 Approximately 92.9 mV dec -1 It is half of that of the control group (108.5 mV dec) and far lower than that of the control group (108.5 mV dec). -1 ) and Comparative Example 3 (111.4 mVdec) -1 The Nyquist curve further confirms that the electrocatalyst prepared in Example 1 of this invention has the fastest interfacial kinetic characteristics.

[0056] Furthermore, by weighing the loading of the water electrolysis catalysts prepared in Example 1 and Comparative Example 1 of the present invention, and based on the assumption that nickel metal atoms are the main effective reaction sites for the OER reaction, the TOF (turnover frequency) of the water electrolysis catalysts prepared in Example 1 and Comparative Example 1 of the present invention was calculated. Combined with LSV performance data, the TOF-normalized LSV curves can be obtained. Figure 13 The TOF curves of the water electrolysis catalysts prepared in Example 1 and Comparative Example 1 are shown. Within the measured potential range, the TOF value of Example 1 of this invention is 30-50 times higher than that of Comparative Example 1, clearly demonstrating the intrinsic activity enhancement effect brought about by the PDA interlayer.

[0057] Furthermore, by weighing the water electrolysis catalysts prepared in Example 1 and Comparative Example 1 of the present invention and combining the LSV performance data, the mass activity of the water electrolysis catalysts prepared in Example 1 and Comparative Example 1 of the present invention can be obtained. Figure 14 The graphs show the mass activity curves of the water electrolysis catalysts prepared in Example 1 and Comparative Example 1. Figure 14 As shown, within the measurement potential range, the mass activity of Example 1 of the present invention reaches 3819 Ag at an overpotential of 360 mV. -1 This is 38.3 times that of Comparative Example 1, which clearly demonstrates that the performance improvement stems from a significant enhancement of the intrinsic activity of each active site, rather than an increase in the number of active sites.

[0058] Furthermore, by setting the timing potentiometry (CP) program, the current density was set to 0.5 A cm⁻¹. -2 Long-term stability test data of the water electrolysis catalysts prepared in Example 1 and Comparative Example 1 of this invention were obtained. Figure 15 Chronovoltaic stability test results (current density 0.5 A cm⁻¹) of the water electrolysis catalysts prepared in Example 1 and Comparative Example 1. -2 ).like Figure 15 As shown, the water electrolysis catalyst prepared in Example 1 of this invention operated continuously for over 1100 hours, exhibiting excellent operational stability. In contrast, the water electrolysis catalyst prepared in Comparative Example 1 of this invention showed rapid deactivation within 130 hours. Furthermore, the current density was set to 1.0 A cm⁻¹. -2 Long-term stability test data of the water electrolysis catalyst prepared in Example 1 of this invention at a higher current density were obtained. Figure 16 Chrono-voltage stability test curve of the water electrolysis catalyst prepared in Example 1 (current density 1.0 A cm⁻¹). -2 ).like Figure 16 As shown, Embodiment 1 of the present invention operated for more than 500 hours. These figures highlight the superior durability of Embodiment 1 of the present invention.

[0059] Furthermore, by comparing the activity data of OER water electrolysis catalysts in existing studies, visual competitive data of the water electrolysis catalyst prepared in Example 1 of this invention were obtained. Figure 17 A comparison of the performance of the water electrolysis catalyst prepared in Example 1 of this invention with data from existing literature (current density 0.5 A cm⁻¹). -2 ). Figure 18 A comparison of the performance of the water electrolysis catalyst prepared in Example 1 of this invention with data from existing literature (current density 1.0 A cm⁻¹). -2 ).like Figure 17-18 As shown, the water electrolysis catalyst prepared in Example 1 of this invention exhibits better competitiveness compared to other recently reported catalysts in terms of overpotential and Tafel slope. Table 1 (corresponding to...) Figure 17 ) and Table 2 (corresponding) Figure 18 (This is a literature source for existing OER water electrolysis catalysts.)

[0060] Table 1 Table 2 Application Example 2 This invention does not limit the utilization of water electrolysis catalysts to small-scale laboratory settings. This invention constructs an anion exchange membrane water electrolyzer (AEMWE) to evaluate the industrial application potential of the water electrolysis catalyst prepared in Example 1. The activity of the water electrolysis catalysts prepared in Example 1 and Comparative Examples 1-2 was evaluated in the anion exchange membrane water electrolyzer system. The electrochemical workstation used was (DH7003A, Donghua Analytical Instruments), the test system was AEMWE, and the anode was the electrocatalyst prepared in Example 1 and Comparative Examples 1-2 (effective geometric area 1.5 × 1.5 cm²). 2 ), Pt / C (1 mg Pt cm -2 A 1.5 × 1.5 cm² anion exchange membrane (AEM) was used as the cathode. Before testing, the AEM was pretreated by immersing it in 1.0 M KOH solution for at least 12 h to complete ion exchange. The electrolyte was 1.0 M KOH solution, and the circulation flow rate was 40 mL / min. -1 By setting the timing potentiometric (CP) program, from 0 to 1.5 A cm⁻¹ -2 The steady-state electrolyzer voltage was measured within a constant current density range, and the current-voltage polarization curves of the water electrolysis catalysts prepared in Example 1 and Comparative Examples 1-2 of this invention were obtained. Figure 19 Performance graphs of AEMWE assemblies for the water electrolysis catalysts prepared in Examples 1, 1, and 2. Figure 19 As shown, the AEWWE constructed from the water electrolysis catalyst prepared in Example 1 of this invention requires only 1.92±0.01, 2.13±0.02, and 2.19±0.02 volts at room temperature to achieve 0.5, 1.0, and 1.5 A cm⁻¹ of voltage, respectively. -2 The current density, which surpasses the performance of the AEWWE constructed from the water electrolysis catalysts prepared in Comparative Examples 1-2 over a wide current density range, highlights the industrialization potential of Example 1 of the present invention.

[0061] Furthermore, by setting the timing potentiometry (CP) program, the current density was set to 1.0 A cm⁻¹. -2 Long-term stability test data of AEMWE constructed from the water electrolysis catalyst prepared in Example 1 of this invention were obtained. Figure 20 Chrono-voltage stability test results of the AEMWE assembly containing the water electrolysis catalyst prepared in Example 1 (current density 1.0 A cm⁻¹). -2 ),like Figure 20 As shown, the AEMWE constructed from the water electrolysis catalyst prepared in Example 1 operated continuously for more than 2100 hours at room temperature, demonstrating its excellent potential as a candidate solution in the field of industrial water electrolysis.

[0062] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A water electrolysis catalyst based on a polydopamine interlayer achieving electrochemical-mechanical dual stabilization, characterized in that, The water electrolysis catalyst has a three-dimensional layered structure; the water electrolysis catalyst includes a metal conductive substrate, a polydopamine intermediate layer and a catalyst layer.

2. The water electrolysis catalyst based on a polydopamine interlayer for electrochemical-mechanical dual stabilization according to claim 1, characterized in that, The conductive metal substrate is nickel foam; the thickness of the polydopamine interlayer is 100-200 nm; and the size of the nickel-iron layered double hydroxide nanosheets in the catalyst layer is 50-100 nm.

3. A method for preparing an electrochemically-mechanically stabilized water electrolysis catalyst based on a polydopamine interlayer as described in claim 1 or 2, characterized in that, Using nickel foam as a three-dimensional conductive substrate, a polydopamine interlayer is first deposited on the nickel foam through the self-polymerization reaction of dopamine hydrochloride in an alkaline environment. Then, an etching reaction is carried out in a homogeneous solution containing ferric nitrate and sodium thiosulfate to form a catalyst layer, thus preparing the electrochemical-mechanical dual stabilization water electrolysis catalyst based on the polydopamine interlayer.

4. The preparation method according to claim 3, characterized in that, The specific preparation method includes the following steps: dissolving dopamine hydrochloride in Tris-HCl buffer, immersing pretreated nickel foam in Tris-HCl buffer containing dopamine hydrochloride, performing an initial stirring reaction, removing the nickel foam after the initial stirring reaction, washing it, and vacuum drying it at 25 °C to obtain polydopamine / nickel foam; immersing the polydopamine / nickel foam in a homogeneous solution containing ferric nitrate and sodium thiosulfate, performing a secondary stirring reaction, removing the nickel foam after the secondary stirring reaction, washing it, and drying it under a nitrogen atmosphere to obtain the electrochemical-mechanical dual stabilization water electrolysis catalyst based on the polydopamine intermediate layer.

5. The preparation method according to claim 4, characterized in that, The concentration of the Tris-HCl buffer solution is 0.1-0.5 M, and the pH is 8.5-8.8; the concentration of dopamine hydrochloride in the Tris-HCl buffer solution is 0.5-2 mg / mL. -1 .

6. The preparation method according to claim 4, characterized in that, The concentrations of ferric nitrate and sodium thiosulfate in the homogeneous solution were 0.086 mol / L and 0.02 mol / L, respectively.

7. The preparation method according to claim 4, characterized in that, The initial stirring reaction was carried out at room temperature, with a stirring speed of 350 rpm and a reaction time of 6 h. The vacuum drying time is 12 hours; The specific operation of the secondary stirring reaction is as follows: shake at 200 rpm for 5 minutes in a shaker at room temperature; The drying process under nitrogen atmosphere was carried out at room temperature for 4 hours.

8. The preparation method according to claim 4, characterized in that, When the dopamine hydrochloride is dissolved in Tris-HCl buffer, a co-solvent is also added; the volume ratio of the co-solvent to the Tris-HCl buffer is 1:1; the co-solvent is selected from anhydrous ethanol.

9. The application of the electrolytic water catalyst based on a polydopamine interlayer for electrochemical-mechanical dual stabilization as described in claim 1 or 2 in a three-electrode electrolyzer.

10. The application of the electrolytic water catalyst based on a polydopamine interlayer for electrochemical-mechanical dual stabilization as described in claim 1 or 2 in an anion exchange membrane electrolyzer.

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