Dead-weight configuration oxygen evolution electrode, preparation method and application

Abstract

The invention discloses a self-weight configuration oxygen evolution electrode and a preparation method and application thereof.The preparation method comprises the steps that a nickel substrate serving as a working electrode, a platinum sheet serving as a counter electrode and a saturated calomel electrode serving as a reference electrode are placed in a NiCo2O4 precursor solution, constant-potential electro-deposition is conducted on the nickel substrate, and a precursor electrode with a Ni-Co LDH precursor on the surface is obtained; putting the precursor electrode into a heating device for heating and heat preservation, and then taking out the precursor electrode for cooling to obtain a NiCo2O4 electrode with a spinel structure; and sequentially putting the NiCo2O4 electrode into a ferric nitrate nonahydrate aqueous solution and a sodium hydroxide solution, and loading alpha-Fe2O3 nanoparticles on the surface of the NiCo2O4 electrode by using a continuous ion layer adsorption reaction method to obtain the self-weight configuration oxygen evolution electrode. According to the preparation method of the self-weight configuration oxygen evolution electrode, a composite catalyst layer composed of NiCo2O4 and alpha-Fe2O3 of a spinel structure is constructed on a nickel substrate, and the self-weight configuration oxygen evolution electrode can adapt to power fluctuation.

Description

Technical Field

[0001] This invention belongs to the field of electrolytic hydrogen production technology, specifically relating to a self-reconfigurable oxygen evolution electrode, its preparation method, and its application. Background Technology

[0002] Faced with the rapid depletion of traditional fossil fuels and environmental pollution, utilizing renewable energy to produce hydrogen is a crucial measure for achieving large-scale carbon emission reduction, playing a significant role in chemical engineering, transportation, and energy storage. Key factors influencing the cost of renewable energy-based hydrogen production include the cost of the electrolyzer equipment and the cost of electricity. Currently, alkaline water electrolysis technology generally requires stable or near-stable power supply. Renewable energy sources such as wind and solar power have inherent volatility, leading to unstable operation of the electrolyzer and hindering efficient energy utilization. For example, when the input power fluctuates, transient changes occur in temperature and potential within the electrolyzer, and the mass transfer response of water and alkali is slow, resulting in localized high temperatures or voltages within the electrolyzer. This severely damages core components such as the diaphragm and electrodes, affecting the electrolyzer's lifespan and significantly increasing operating costs. The electrodes, as the primary site of water electrolysis, are crucial for catalytic water splitting. Ensuring stable and efficient electrode operation under fluctuating current densities is paramount, but traditional electrodes struggle to maintain stable and efficient electrolysis performance simultaneously under both low and high loads.

[0003] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a self-reconfigurable oxygen evolution electrode, which constructs a composite catalytic layer on a nickel substrate composed of spinel-structured NiCo2O4 and α-Fe2O3, which can adapt to power fluctuations.

[0005] To achieve the above objectives, a specific embodiment of the present invention provides a method for preparing a self-reconfigurable oxygen evolution electrode, comprising: placing a nickel substrate as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode in a NiCo2O4 precursor solution; performing constant potential electrodeposition on the nickel substrate to obtain a precursor electrode with a Ni-Co LDH precursor on its surface; heating and holding the precursor electrode in a heating device, and then removing the precursor electrode for cooling to obtain a NiCo2O4 electrode with a spinel structure; sequentially placing the NiCo2O4 electrode in an aqueous solution of ferric nitrate nonahydrate and a sodium hydroxide solution, and loading α-Fe2O3 nanoparticles on the surface of the NiCo2O4 electrode using a continuous ion layer adsorption reaction method to obtain a self-reconfigurable oxygen evolution electrode.

[0006] In one or more embodiments of the present invention, the deposition potential of the constant potential electrodeposition relative to the saturated calomel electrode is -0.5 to -2.0 V; the deposition temperature is 25 to 30 °C; and the deposition time is 5 to 30 min.

[0007] In one or more embodiments of the present invention, placing the precursor electrode in a heating device for heating and holding at a certain temperature, and then removing the precursor electrode for cooling includes: heating the precursor electrode in the heating device at a heating rate of 2~4°C / min to 250~500°C and holding at that temperature for 2~3 hours, and then naturally cooling it to 20~30°C.

[0008] In one or more embodiments of the present invention, loading α-Fe2O3 nanoparticles onto the surface of the NiCo2O4 electrode using a continuous ion-layer adsorption reaction method comprises: immersing the NiCo2O4 electrode in an aqueous solution of ferric nitrate nonahydrate for 5-30 seconds to allow Fe2O3 nanoparticles to be loaded onto the surface of the NiCo2O4 electrode. 3+ The adsorption is applied to the surface of the NiCo2O4 electrode, then removed and rinsed in deionized water for 25-35 seconds; the rinsed NiCo2O4 electrode is then immersed in sodium hydroxide solution for 20-60 seconds, so that the OH... - Fe on the surface of the NiCo2O4 electrode 3+ The reaction produces Fe(OH)3 precipitate, which is removed and rinsed with deionized water for 25-35 seconds. The above two steps are repeated several times, and then the rinsed NiCo2O4 electrode is dried at 55-65°C. The dried NiCo2O4 electrode is then heat-treated in air at 200-400°C for 0.5-2 hours to convert amorphous Fe(OH)3 into α-Fe2O3 and load it onto the surface of the NiCo2O4 electrode.

[0009] In one or more embodiments of the present invention, the concentration of the ferric nitrate nonahydrate aqueous solution is 0.02~0.04M; and / or, the concentration of the sodium hydroxide solution is 0.08~0.16M.

[0010] In one or more embodiments of the present invention, the preparation of the precursor solution includes: dissolving nickel nitrate hexahydrate, cobalt nitrate hexahydrate and sodium nitrate in deionized water, stirring magnetically for 25 to 35 minutes until completely clear and transparent, and adjusting the pH to 6 to 6.5 to obtain the NiCo2O4 precursor solution.

[0011] In one or more embodiments of the present invention, the concentration of nickel nitrate hexahydrate is 0.05~0.1 M; and / or the concentration of cobalt nitrate hexahydrate is 0.1~0.2 M; and / or the concentration of sodium nitrate is 0.1~0.2 M.

[0012] In one or more embodiments of the present invention, the method for preparing the self-reconfigurable oxygen evolution electrode further includes pretreatment of the nickel substrate; the pretreatment includes: ultrasonically cleaning the nickel substrate sequentially in acetone, anhydrous ethanol, and deionized water for 10-20 min; immersing the cleaned nickel substrate in dilute hydrochloric acid for 5-10 min; removing the nickel substrate from the dilute hydrochloric acid and rinsing it with deionized water, and then drying it in a vacuum drying oven at 55-65°C for 2-3 h.

[0013] Another specific embodiment of the present invention provides a self-reconfigurable oxygen evolution electrode prepared using the preparation method described in any of the foregoing embodiments.

[0014] Another specific embodiment of the present invention provides the application of a self-reconfigurable oxygen evolution electrode as described above in the field of hydrogen production by alkaline electrolysis of water using a fluctuating power supply.

[0015] Compared with existing technologies, the self-reconfigurable oxygen evolution electrode of this invention utilizes a two-step method—potentially constant electrodeposition and continuous ion layer adsorption reaction—to construct a composite catalytic layer composed of spinel-structured NiCo2O4 and α-Fe2O3 on a nickel substrate. The nickel substrate provides a conductive framework and a large specific surface area. The NiCo2O4 layer acts as a highly efficient OER catalyst under low to moderate current densities of fluctuating power supplies. Highly dispersed α-Fe2O3 nanoparticles serve as a "backup" catalyst precursor. When the input power of the fluctuating power supply increases dramatically and the current density rises to a certain critical value, the electrode potential increases accordingly. Under high potential and strongly alkaline conditions, the originally weakly active α-Fe2O3 undergoes irreversible electrochemical reconstruction, transforming into ultra-highly active γ-FeOOH (or iron-doped Ni / CoOOH). This process occurs in situ, thereby achieving a "self-upgrade" catalytic capability of the electrode under high power fluctuations, ensuring that the electrode always maintains a high-efficiency state. Therefore, under low current density (such as when wind and solar power generation is weak), the activity of this self-reconfigurable oxygen evolution electrode is mainly provided by NiCo2O4. When the current density increases sharply, α-Fe2O3 will be converted in situ into highly active γ-FeOOH at high potential, realizing "self-reconfiguration" to adapt to power fluctuations. This solves the problem of high oxygen evolution efficiency of the electrode under wide current density. The self-reconfiguration process is fast and can keep up with the rapid changes of fluctuating power supply, avoiding the rapid deactivation of a single material under non-design conditions. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart of a method for preparing a self-reconfigurable oxygen evolution electrode according to an embodiment of the present invention;

[0018] Figure 2 The diagram shows the initial state and LSV curve of the self-reconfigurable oxygen evolution electrode after reconfiguration and activation in Embodiment 1 of the present invention.

[0019] Figure 3 This is a stability curve of a self-reconfigurable oxygen evolution electrode in one embodiment of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0021] like Figure 1 As shown, a method for preparing a self-reconfigurable oxygen evolution electrode in one embodiment of the present invention includes steps S1-S3.

[0022] Step S1: Place a nickel substrate as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode in a NiCo2O4 precursor solution, and perform constant potential electrodeposition on the nickel substrate to obtain a precursor electrode with a Ni-Co LDH (Ni-Co layered double hydroxide) precursor on its surface.

[0023] Specifically, in step S1, nickel nitrate hexahydrate, cobalt nitrate hexahydrate, and sodium nitrate are first dissolved in deionized water, and the solution is magnetically stirred for 25-35 minutes until completely clear and transparent, and the pH is adjusted to 6-6.5 to obtain a NiCo2O4 precursor solution. Preferably, the concentration of nickel nitrate hexahydrate is 0.05-0.1 M (mol / L), the concentration of cobalt nitrate hexahydrate is 0.1-0.2 M, and the concentration of sodium nitrate is 0.1-0.2 M.

[0024] Next, using a three-electrode system, the pretreated nickel substrate is placed in a prepared NiCo2O4 precursor solution as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode, for constant potential electrodeposition of the nickel substrate. Preferably, the deposition potential for constant potential electrodeposition is -0.5 to -2.0 V (vs. SCE), where vs. SCE refers to the deposition voltage relative to the saturated calomel electrode; the deposition temperature is 25 to 30 °C; and the deposition time is 5 to 30 min. Additionally, during constant potential electrodeposition, a magnetic stir bar can be added to the precursor solution and its rotation speed controlled at 180 to 220 rpm to stir the precursor solution, ensuring that the NiCo2O4 precursor is uniformly deposited on the surface of the nickel substrate.

[0025] After the constant potential electrodeposition of nickel substrate is completed, the nickel substrate is removed and rinsed repeatedly with deionized water to remove loosely attached particles on the surface of the nickel substrate. Then, the nickel substrate is dried at 55-65℃ for 1-2 hours to obtain a precursor electrode with Ni-Co LDH precursor on the surface.

[0026] In one embodiment, the nickel substrate can be selected from pure nickel materials such as nickel mesh, nickel foam, and nickel felt. Preferably, the nickel substrate is nickel foam. Since the surface of the nickel substrate may become contaminated with dirt, oil, and form an oxide layer during storage, the nickel substrate can be pretreated before use. Specifically, the pretreatment of the nickel substrate includes: first, cutting the nickel substrate with an area density ≥320 g / m² into (2-3) cm * (4-5) cm pieces; then, ultrasonically cleaning the nickel substrate sequentially in acetone, anhydrous ethanol, and deionized water for 10-20 min to remove grease and contaminants from the surface of the nickel substrate. Next, immersing the ultrasonically cleaned nickel substrate in 2-4 M dilute hydrochloric acid for 5-10 min to remove the oxide layer on the surface of the nickel substrate and hydrophilize it to facilitate the adhesion of the subsequent precursor layer. Then, removing the nickel substrate from the dilute hydrochloric acid and rinsing it with deionized water, and then drying it in a vacuum drying oven at 55-65°C for 2-3 h to obtain the pretreated nickel substrate.

[0027] Step S2: Place the precursor electrode in a heating device for heating and heat preservation, then remove the precursor electrode for cooling to obtain a NiCo2O4 electrode with a spinel structure.

[0028] Specifically, in step S2, the dried precursor electrode is placed in a heating device, such as a muffle furnace or a tube furnace, and heated to 250-500°C at a heating rate of 2-4°C / min and held at that temperature for 2-3 hours. Then, it is naturally cooled to 20-30°C, so that the precursor electrode with Ni-Co LDH precursor on its surface is transformed into a NiCo2O4 electrode with high catalytic activity.

[0029] Step S3: The NiCo2O4 electrode is placed in an aqueous solution of ferric nitrate nonahydrate and a sodium hydroxide solution in sequence. α-Fe2O3 nanoparticles are loaded on the surface of the NiCo2O4 electrode using a continuous ion layer adsorption reaction method to obtain a self-reconfigurable oxygen evolution electrode for fluctuating power supplies.

[0030] Specifically, in step S3, the NiCo2O4 electrode is immersed in an aqueous solution of ferric nitrate nonahydrate for 5-30 seconds to allow Fe... 3+ The ions are adsorbed onto the surface of the NiCo2O4 electrode. The NiCo2O4 electrode is then removed and immersed in deionized water for 25-35 seconds to remove excess ions physically adsorbed on its surface. Preferably, the concentration of the ferric nitrate nonahydrate aqueous solution is 0.02-0.04 M.

[0031] Next, the washed NiCo2O4 electrode was immersed in sodium hydroxide solution for 20-60 seconds, so that the OH... - Fe on the surface of NiCo2O4 electrode 3+ The reaction produces Fe(OH)3 precipitate, which is then removed and rinsed with deionized water for 25-35 seconds to remove byproducts and loose particles. Preferably, the concentration of the sodium hydroxide solution is 0.08-0.16 M.

[0032] Repeat the above two steps multiple times to ensure that a high-purity, high-bonding-strength α-Fe2O3 nanoparticle thin layer is obtained on the surface of the NiCo2O4 electrode. Preferably, repeat the above two steps 10-20 times. Then, dry the immersed NiCo2O4 electrode at 55-65°C.

[0033] The dried NiCo2O4 electrode is heat-treated in air at 200~400°C for 0.5~2 hours to convert amorphous Fe(OH)3 into α-Fe2O3 and load it on the surface of the NiCo2O4 electrode, thereby obtaining a self-reconfigurable oxygen evolution electrode with NiCo2O4 and α-Fe2O3 loaded on its surface.

[0034] The fabrication method of this self-reconfigurable oxygen evolution electrode utilizes a two-step process—potentially constant electrodeposition and sequential ion layer adsorption reaction—to construct a composite catalytic layer composed of spinel-structured NiCo2O4 and α-Fe2O3 on a nickel substrate. At low to medium current densities, the spinel-structured NiCo2O4 on the surface of the self-reconfigurable oxygen evolution electrode provides activity; under high potential and strongly alkaline conditions, α-Fe2O3 transforms into ultra-highly active γ-FeOOH (or iron-doped Ni / CoOOH), achieving the "self-reconfiguration" of the oxygen evolution electrode to adapt to power fluctuations in the fluctuating power supply.

[0035] The present invention will be further described below with reference to specific embodiments and comparative examples.

[0036] Example 1

[0037] Step S1: Select nickel foam with an areal density of 400 g / m² as the nickel substrate and cut it into 2 cm * 4 cm pieces. Next, ultrasonically clean the nickel substrate sequentially in acetone, anhydrous ethanol, and deionized water for 15 min each. Then, immerse the ultrasonically cleaned nickel substrate in 3M dilute hydrochloric acid for 5 min. Remove the nickel substrate from the dilute hydrochloric acid and rinse with deionized water, then dry it in a vacuum drying oven at 60°C for 2 h to obtain the pretreated nickel substrate. Dissolve 0.05 M nickel nitrate hexahydrate, 0.1 M cobalt nitrate hexahydrate, and 0.1 M sodium nitrate in deionized water, stir magnetically for 30 min until completely clear and transparent, and adjust the pH to 6.5 to obtain the NiCo₂O₄ precursor solution. Use the pretreated nickel substrate as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode in the prepared NiCo₂O₄ precursor solution to perform potentiostatic electrodeposition on the nickel substrate. The deposition potential was -1V (vs. SCE), the deposition temperature was 25℃, and the deposition time was 20 min. The magnetic stir bar rotated at 200 rpm. After the constant potential electrodeposition on the nickel substrate was completed, the nickel substrate was removed, rinsed repeatedly with deionized water, and then dried at 60℃ for 1 h to obtain a precursor electrode with a Ni-Co LDH precursor on its surface.

[0038] Step S2: Place the dried precursor electrode into a muffle furnace, heat it to 300°C at a heating rate of 2°C / min and hold it at that temperature for 2 hours, then allow it to cool naturally to 25°C.

[0039] Step S3: Immerse the NiCo2O4 electrode in a 0.02M ferric nitrate nonahydrate solution for 20 seconds, then remove the NiCo2O4 electrode and rinse it in deionized water for 30 seconds. Next, immerse the rinsed NiCo2O4 electrode in a 0.08M sodium hydroxide solution for 30 seconds, then remove it and rinse it with deionized water for 30 seconds.

[0040] Repeat the above two steps 10 times. Then dry the NiCo2O4 electrode after immersion at 60°C.

[0041] The dried NiCo2O4 electrode was heat-treated in air at 300°C for 1 hour to obtain a self-reconfigurable oxygen evolution electrode.

[0042] Example 2

[0043] The difference from Example 1 is that the electrodeposition potential is -2V (vs. SCE).

[0044] Example 3

[0045] The difference from Example 1 is that the electrodeposition time is 30 min.

[0046] Example 4

[0047] The difference from Example 1 is that in step S2, the temperature is increased to 500°C at a heating rate of 2°C / min.

[0048] Example 5

[0049] The difference from Example 1 is that in step S3, the NiCo2O4 electrode is immersed in a 0.02M ferric nitrate nonahydrate aqueous solution for 30s; and the NiCo2O4 electrode is immersed in a 0.08M sodium hydroxide solution for 60s, and the two steps are repeated 5 times.

[0050] Example 6

[0051] The difference from Example 1 is that in step S3, the NiCo2O4 electrode is immersed in a 0.02M ferric nitrate nonahydrate aqueous solution for 30 seconds; and the NiCo2O4 electrode is immersed in a 0.08M sodium hydroxide solution for 60 seconds, and the two steps are repeated 20 times.

[0052] Example 7

[0053] The difference from Example 1 is that in step S3, the dried NiCo2O4 electrode is heat-treated in air at 400°C for 0.5 hours.

[0054] Example 8

[0055] The difference from Example 1 is that in step S3, the dried NiCo2O4 electrode is heat-treated in air at 300°C for 1.5 hours.

[0056] Example 9

[0057] The difference from Example 1 is that in step S3, the dried NiCo2O4 electrode is heat-treated in air at 200°C for 2 hours.

[0058] Comparative Example 1

[0059] The difference from Example 1 is that in step S2, the temperature is increased to 650°C at a heating rate of 2°C / min.

[0060] Comparative Example 2

[0061] The difference from Example 1 is that the NiCo2O4 electrode was immersed in a 0.02M ferric nitrate nonahydrate aqueous solution and a 0.08M sodium hydroxide solution for 50 times.

[0062] Comparative Example 3

[0063] The difference from Example 1 is that in step S3, the dried NiCo2O4 electrode is heat-treated in air at 500°C for 10 minutes.

[0064] Comparative Example 4

[0065] The difference from Example 1 is that only steps S1 and S2 were performed to obtain an oxygen evolution electrode with only a NiCo2O4 catalyst layer on the surface.

[0066] Comparative Example 5

[0067] The difference from Example 1 is that the nickel substrate was immersed in a 0.02M ferric nitrate nonahydrate aqueous solution for 20 seconds, and then the nickel substrate was removed and rinsed in deionized water for 30 seconds. Next, the rinsed nickel substrate was immersed in a 0.08M sodium hydroxide solution for 30 seconds, and then removed and rinsed with deionized water for 30 seconds.

[0068] Repeat the above two steps 10 times. Then dry the rinsed nickel substrate at 60°C.

[0069] The dried nickel substrate was heat-treated in air at 300°C for 1 hour to obtain an oxygen evolution electrode with only an α-Fe2O3 catalyst layer.

[0070] Electrochemical tests were performed on the electrodes prepared in Examples 1-9 and Comparative Examples 1-5. Specifically, the electrochemical tests were conducted using a BioLogic electrochemical workstation, with a saturated calomel reference electrode. The LSV curves of the electrodes prepared in Examples 1-9 and Comparative Examples 1-5 were measured in 30 wt% KOH solution at 80 °C, and the current density of 500 mA / cm² was calculated. 2 Oxygen evolution overpotential (ORE overpotential) under certain conditions.

[0071] Table 1. Test data of electrodes prepared in Examples 1-9 and Comparative Examples 1-5

[0072]

[0073] As shown in the table above, the oxygen evolution electrodes of Examples 1-9 have lower OER overpotentials compared to those of Comparative Examples 1-5. The lower the overpotential, the lower the energy consumption required for the oxygen evolution reaction to occur and the higher the activity of the oxygen evolution electrode.

[0074] The oxygen evolution electrodes prepared in Comparative Examples 4 and 5 were tested under fluctuating power supply conditions. The oxygen evolution electrode in Comparative Example 4, due to having only a NiCo2O4 catalyst layer, could operate stably at low to medium current densities under fluctuating power supply conditions, but its efficiency decreased rapidly or it even failed to operate at high current densities. The oxygen evolution electrode in Comparative Example 5, due to having only an α-Fe2O3 catalyst layer, could not operate stably under low to medium current densities under fluctuating power supply conditions.

[0075] The self-reconfigurable oxygen evolution electrode from Example 1 was tested at a low scan rate, and the initial LSV curve of the self-reconfigurable oxygen evolution electrode was also tested after the electrode underwent "reconfiguration activation" (polarization at a high constant current density for several hours). Figure 2 As shown, the initial OER performance of the self-reconfigurable oxygen evolution electrode is 277mV@5000A / m. 2 After self-reconfiguration, the electrode performance is 254mV@5000A / m 2 Therefore, the LSV curve after reconstruction and activation shows that the electrode can achieve a higher current density under the same overpotential, indicating that the self-reconfigurable oxygen evolution electrode has achieved "self-upgrade" under high voltage and can meet the requirements of high voltage use.

[0076] The stability of the self-reconfigurable oxygen evolution electrode of Example 1 was tested. Specifically, the self-reconfigurable oxygen evolution electrode of Example 1 was operated under fluctuating power supply for 1000 hours. The current density was set to jump between multiple steps, with each step maintained for a period of time, and the potential-time curve was recorded. The anode of the electrolytic cell was the self-reconfigurable oxygen evolution electrode of Example 1, the cathode was a pure nickel mesh, the diaphragm was a PPS diaphragm, the electrolyte was 30wt% KOH, and the cell temperature was 82℃.

[0077] like Figure 3 As shown, when the current changes stepwise, the potential of the self-reconfigurable oxygen evolution electrode of Example 1 can quickly stabilize to a new platform, with fast response and good dynamic performance, indicating that the self-reconfigurable oxygen evolution electrode of Example 1 has excellent stability under fluctuating power supply output.

[0078] Another embodiment of the present invention provides a self-reconfigurable oxygen evolution electrode prepared using the above-described preparation method.

[0079] Another embodiment of the present invention provides an application of a self-reconfigurable oxygen evolution electrode in the field of hydrogen production by alkaline electrolysis of water using a fluctuating power supply.

[0080] In summary, the preparation method of the self-reconfigurable oxygen evolution electrode of the present invention utilizes a two-step process—potential constant electrodeposition and continuous ion layer adsorption reaction—to construct a composite catalytic layer composed of spinel-structured NiCo2O4 and α-Fe2O3 on a nickel substrate. The nickel substrate provides a conductive framework and a large specific surface area. The NiCo2O4 layer acts as a highly efficient OER catalyst under low to moderate current densities of fluctuating power supplies. The highly dispersed α-Fe2O3 nanoparticles serve as a "backup" catalyst precursor. When the input power of the fluctuating power supply increases dramatically and the current density rises to a certain critical value, the electrode potential increases accordingly. Under high potential and strongly alkaline conditions, the originally weakly active α-Fe2O3 undergoes irreversible electrochemical reconstruction, transforming into ultra-highly active γ-FeOOH (or iron-doped Ni / CoOOH). This process occurs in situ, thereby achieving a "self-upgrade" catalytic capability of the electrode under high power fluctuations, ensuring that the electrode always maintains a high-efficiency state. Therefore, under low current density (such as when wind and solar power generation is weak), the activity of this self-reconfigurable oxygen evolution electrode is mainly provided by NiCo2O4. When the current density increases sharply, α-Fe2O3 will be converted in situ into highly active γ-FeOOH at high potential, realizing "self-reconfiguration" to adapt to power fluctuations. This solves the problem of high oxygen evolution efficiency of the electrode under wide current density. The self-reconfiguration process is fast and can keep up with the rapid changes of fluctuating power supply, avoiding the rapid deactivation of a single material under non-design conditions.

[0081] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0082] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing a self-reconfigurable oxygen evolution electrode, characterized in that, The application relates to a self-reconstruction type oxygen evolution electrode and a preparation method thereof. A nickel substrate is taken as a working electrode, a platinum sheet is taken as a counter electrode, and a saturated mercury-mercury oxide electrode is taken as a reference electrode, the nickel substrate is subjected to constant potential electrodeposition in a NiCo2O4 precursor solution, and a precursor electrode with a Ni-Co LDH precursor on the surface is obtained; The precursor electrode is placed in a heating device for heating and heat preservation, then the precursor electrode is taken out for cooling, and a NiCo2O4 electrode with a spinel structure is obtained; The NiCo2O4 electrode is sequentially placed in an iron nitrate nonahydrate aqueous solution and a sodium hydroxide solution, alpha-Fe2O3 nanoparticles are loaded on the surface of the NiCo2O4 electrode by using a continuous ion layer adsorption reaction method, and a self-reconstruction type oxygen evolution electrode is obtained.

2. The method of claim 1, wherein the self-reconfiguring oxygen evolution electrode is prepared by the steps of: The deposition potential of the constant potential electrodeposition relative to the saturated mercury-mercury oxide electrode is -0.5 to -2.0 V; the deposition temperature is 25 to 30 DEG C; and the deposition time is 5 to 30 min.

3. The method of claim 1, wherein the self-reconfiguring oxygen evolution electrode is prepared by the steps of: The precursor electrode is placed in a heating device for heating and heat preservation, then the precursor electrode is taken out for cooling, and a NiCo2O4 electrode with a spinel structure is obtained; The precursor electrode is heated to 250 to 500 DEG C at a heating rate of 2 to 4 DEG C / min in the heating device and is heat preserved for 2 to 3 h, and then is naturally cooled to 20 to 30 DEG C.

4. The method of claim 1, wherein the self-reconfiguring oxygen evolution electrode is prepared by the steps of: The precursor electrode is heated to 250 to 500 DEG C at a heating rate of 2 to 4 DEG C / min in the heating device and is heat preserved for 2 to 3 h, and then is naturally cooled to 20 to 30 DEG C. immersion of the NiCo2O4 electrode into an aqueous solution of iron nitrate nonahydrate for 5-30 s, so that Fe 3+ is adsorbed onto the surface of the NiCo2O4 electrode, removal and washing in deionized water for 25-35 s; immersing the NiCo2O4 electrode after the soaking into a sodium hydroxide solution for 20-60s, so that OH - reacts with Fe on the surface of the NiCo2O4 electrode to generate Fe(OH)3 precipitate, which is taken out and soaked with deionized water for 25-35s; 3+ reacts with Fe on the surface of the NiCo2O4 electrode to generate Fe(OH)3 precipitate, which is taken out and soaked with deionized water for 25-35s; The above two steps are repeated for multiple times, then the immersed and washed NiCo2O4 electrode is dried at 55 to 65 DEG C; The dried NiCo2O4 electrode is heat treated in air at 200 to 400 DEG C for 0.5 to 2 h, so that amorphous Fe(OH)3 is converted into alpha-Fe2O3 and is loaded on the surface of the NiCo2O4 electrode.

5. The method of claim 1, wherein the self-reconfiguring oxygen evolution electrode is prepared by the steps of: The concentration of the iron nitrate nonahydrate aqueous solution is 0.02 to 0.04 M; and / or, The concentration of the sodium hydroxide solution is 0.08 to 0.16 M.

6. The method of claim 1, wherein the self-reconfiguring oxygen evolution electrode is prepared by the steps of: The preparation of the precursor solution comprises the following steps: dissolving nickel nitrate hexahydrate, cobalt nitrate hexahydrate and sodium nitrate in deionized water, magnetically stirring for 25 to 35 min until completely clear and transparent, and adjusting the pH to 6 to 6.5, so that the NiCo2O4 precursor solution is obtained.

7. The method of claim 6, wherein the self-reconfiguring oxygen evolution electrode is prepared by the steps of: The concentration of the nickel nitrate hexahydrate is 0.05 to 0.1 M; and / or; The concentration of the cobalt nitrate hexahydrate is 0.1 to 0.2 M; and / or; The concentration of the sodium nitrate is 0.1 to 0.2 M.

8. The method of claim 1, wherein the self-reconfiguring oxygen evolution electrode is prepared by the steps of: The nickel substrate is also subjected to pretreatment, and the pretreatment comprises the following steps: The nickel substrate is sequentially ultrasonically cleaned in acetone, anhydrous ethanol and deionized water for 10 to 20 min; The cleaned nickel substrate is immersed in dilute hydrochloric acid for 5 to 10 min; The nickel substrate is taken out from the dilute hydrochloric acid and is washed with deionized water, and then is dried in a vacuum drying box at 55 to 65 DEG C for 2 to 3 h.

9. A self-reconstruction type oxygen evolution electrode prepared by the preparation method in any one of claims 1 to 8.

10. Application of the self-reconstruction type oxygen evolution electrode in claim 9 in the field of hydrogen production by alkaline electrolysis of fluctuating power source water.

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