A high-efficiency water decomposition electrode based on 3d printing nickel-iron alloy and a preparation method thereof

Abstract

The application discloses a high-efficiency water decomposition electrode based on 3D printing of a nickel-iron alloy and a preparation method thereof, and belongs to the technical field of electrodes. First, metal salt resin is printed into a double helix structure through 3D printing; an alloy oxide electrode is obtained by sintering in air; then, the alloy oxide electrode is heated to a reaction temperature and kept constant, hydrogen and argon are introduced, and a reduction reaction is carried out at a set temperature; the alloy nickel-iron electrode is obtained by cooling in the furnace to room temperature; finally, the alloy nickel-iron electrode is taken as a substrate, the alloy nickel-iron electrode is immersed in a RuCl3 solution at room temperature to obtain a Ru-Ni(OH)2 / 3DP NiFe electrode; and the alloy nickel-iron electrode is immersed in a FeCl3 solution at room temperature to obtain a Fe-Ni(OH)2 / 3DP NiFe electrode. The double helix structure has the characteristics of high specific surface area and good structural stability, the alloy composition is regulated to make the electrode have a dual-function catalytic effect, namely, the nickel-iron alloy is used as a dual-function catalytic electrode, and the synergy between the nickel-iron dual transition metals makes the electrode have excellent catalytic performance in HER and OER.

Description

Technical Field

[0001] This invention belongs to the field of electrode technology, specifically relating to a high-efficiency water splitting electrode based on 3D-printed nickel-iron alloy and its preparation method. Background Technology

[0002] With the negative impacts of fossil fuel consumption, there is a growing focus on developing efficient and stable clean energy sources. Hydrogen energy, as a representative of clean energy, is gaining attention due to its unique characteristics, including its only byproduct being unpolluted water and its high energy density. Currently, industrial hydrogen production mainly relies on the steam reforming process of fossil fuels; however, this method still cannot escape dependence on fossil fuels. Water electrolysis, as one method of hydrogen production, is becoming an effective strategy because its raw material is unpolluted and abundant water. Under standard conditions, the free energy (ΔG) change of the water splitting reaction is 474.4 kJ / mol. -1 The reaction (2H₂O→2H₂+O₂) corresponds to an electrolyzer voltage of 1.23V. However, the slow kinetics of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) necessitate additional voltage to drive the water splitting reaction in actual hydrogen production. Therefore, the rational development of exceptionally efficient non-precious metal catalysts to accelerate the large-scale commercialization of overall water splitting is of paramount importance.

[0003] Noble metal-based materials exhibit excellent catalytic activity in water electrolysis, but their scarcity and high cost limit their large-scale application. Therefore, there is an urgent need to develop high-abundance, low-cost, and high-performance water splitting electrocatalysts. Currently, a series of non-noble metal transition metals, such as nickel, cobalt, iron, molybdenum, and tungsten, have attracted considerable attention due to their high abundance and low cost. Among these, nickel-based electrocatalysts, such as oxides, hydroxides, sulfides, nitrides, and alloys, have attracted significant interest due to their low cost, high catalytic activity, and corrosion resistance. Zuo Feng Chen et al. employed a novel electrochemical deposition method to synthesize three-dimensional NiCo, NiCu, and CoCu alloy foams on planar electrode substrates for the hydrogen evolution reaction (HER) and NiFe alloy foams for the oxygen evolution reaction (OER). Teng, X.; Wang, J.; Ji, L.; Liu, Y.; Zhang, C.; Chen, Z. Fabrication of Three-Dimensional Multiscale Porous Alloy Foams at a Planar Substrate for Efficient Water Splitting. ACS Sustainable Chemistry & Engineering 2019, 7, 5412-5419. However, compared to three-dimensional electrodes, planar electrode substrates have smaller electrochemical active areas, limited active sites, and fewer loaded active materials, making it impossible to achieve truly efficient water splitting. Existing technologies include the preparation of unique volcanic FeIr alloys self-supported on nickel foam (NF) via hydrothermal methods, achieving 10 mA cm⁻¹ in 1.0 M KOH. -2 At this level, OER and HER only require overpotentials of 220.0 and 25.6 mV, respectively. However, due to the disordered structure of the nickel foam substrate, the bubbles cannot escape quickly at industrial-grade current densities, causing them to adhere to the electrode surface and reducing the number of electrochemically active sites, thus affecting the overall catalytic effect and hindering practical industrial applications. Other researchers have used polyurethane (PU) sponge as a novel electroplating method to design NiFe alloy foams with different Fe contents for OER. Results show that Fe doping can significantly improve the conductivity and OER performance of the nickel foam. NiFe alloy foam containing 30% Fe at 10 mA cm⁻¹... -2 It exhibits an overpotential of 292 mV, and the Tafel slope in alkaline solution is 126.12 mV. -1However, the chemical plating and electroplating NiFe alloy strategies employed in this method are complex and cumbersome. Furthermore, the microstructure of the electrodeposited material is similar to the smooth skeletal structure of nickel foam, and its electrochemical active area is provided by the active layered material. The structure itself has a smooth microstructure and cannot provide a large electrochemical active area or more active sites. Summary of the Invention

[0004] The technical problem to be solved:

[0005] To overcome the shortcomings of existing technologies, this invention provides a high-efficiency water-splitting electrode based on a compositionally tunable 3D-printed nickel-iron alloy and its preparation method. By combining 3D printing technology (DLP), formulation development, and subsequent sintering process research, a three-dimensional porous, multi-level electrode material is finally realized. Other existing alloy electrodes, such as alloy materials grown by electroplating or hydrothermal methods on a three-dimensional structure, and alloy foams made from commercially available metal foams, only support active materials at laboratory current densities (≤100 mA cm⁻¹). -2 The study was conducted at an industrial-grade current density (≥400 mA cm⁻¹). -2 The present invention relates to a 3D-printed nickel-iron alloy with adjustable composition, which employs a double-helix structure (Gyroid) characterized by high specific surface area and good structural stability. By adjusting the composition of the alloy, the electrode can achieve a bifunctional catalytic effect. That is, by using a nickel-iron alloy as a bifunctional catalytic electrode, the synergistic effect between the nickel and iron transition metals gives it excellent catalytic performance in both HER and OER.

[0006] The technical solution of the present invention is: a high-efficiency water splitting electrode based on 3D printed nickel-iron alloy, including a Ru-Ni(OH)2 / 3DP NiFe electrode and a Fe-Ni(OH)2 / 3DP NiFe electrode, which are used for the hydrogen evolution reaction and oxygen evolution reaction in the water splitting reaction, respectively.

[0007] A method for fabricating a high-efficiency water splitting electrode based on 3D printing of nickel-iron alloy, the specific steps of which are as follows:

[0008] Step 1: First, design a double-helix structure template; then, mix and stir the metal salt, Variquat CC 42NS, hexanediol diacrylate, ethoxylated trimethylolpropane triacrylate, and diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxide to obtain a homogeneous metal salt resin; then, use digital light processing technology to print the metal salt resin into a double-helix structure; finally, sinter in air to obtain an alloy oxide electrode;

[0009] Step 2: Heat the alloy oxide electrode obtained in Step 1 to the reaction temperature and keep it at a constant temperature. Introduce hydrogen and argon gas and carry out the reduction reaction at the set temperature. Cool the furnace to room temperature to obtain the alloy nickel-iron electrode.

[0010] Step 3: Using the nickel-iron alloy electrode obtained in Step 2 as the substrate for in-situ growth of hydroxide, an electrolytic water electrode is prepared by a corrosion-induced strategy: the corrosion reaction solution is RuCl3 solution. After immersing the nickel-iron alloy electrode in RuCl3 solution at room temperature for 2-6 hours, the surface of the nickel-iron alloy electrode is etched to form metal hydroxide, which is used as the electrode for the HER reaction, namely Ru-Ni(OH)2 / 3DP NiFe.

[0011] Step 4: Using the nickel-iron alloy electrode obtained in Step 2 as the substrate for in-situ growth of hydroxides, an electrolytic water electrode is prepared using a corrosion-induced strategy: The corrosion reaction solution is FeCl3 solution. After immersing the nickel-iron alloy electrode in FeCl3 solution at room temperature for 2-6 hours, the surface of the nickel-iron alloy electrode is etched to form metal hydroxides, which serve as the electrode for the OER reaction, namely Fe-Ni(OH)2 / 3DP NiFe.

[0012] A further technical solution of the present invention is as follows: In step 1, before preparing the printing ink, NiSO4·6H2O is placed in a muffle furnace for dehydration by air burning at a temperature of 100-200℃, with a heating rate of 3-5℃ / min and a dehydration time of 3-5 hours, to obtain the metal salt NiSO4; FeSO4·7H2O is placed in a tube furnace for dehydration at a temperature of 80-90℃, with a heating rate of 3-5℃ / min and a dehydration time of 1-5 hours, with argon gas provided for protection throughout the dehydration process, and a gas flow rate of 100-200mL / min, to obtain the metal salt FeSO4.

[0013] A further technical solution of the present invention is as follows: In step 1, 10-30g of metal salt, 1-10mL of Variquat CC42NS, 5-15mL of hexanediol diacrylate, 1-10mL of ethoxylated trimethylolpropane triacrylate, and 0.2-1g of diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxychloride are mixed; the mixture is stirred at room temperature for 24 hours, and then ball-milled 1-5 times, each time for 60 minutes, with an interval of 5-15 minutes between each milling; wherein, the metal salt includes NiSO4 and FeSO4 in a mass ratio of 2:1; the volume ratio of hexanediol diacrylate to ethoxylated trimethylolpropane triacrylate is 22:3; and diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxychloride accounts for 2% of the total volume of the hexanediol diacrylate and ethoxylated trimethylolpropane triacrylate solutions.

[0014] A further technical solution of the present invention is as follows: In step 1, the sintering gradient temperature is 85℃, 200℃, 400℃, 480℃, 600℃, 800℃, 840℃, and 1000℃; specifically, it is limited to: from 20℃ to 85℃, the heating rate is 1℃ / min, and the temperature is held at 85℃ for 2 hours; from 85℃ to 200℃, the heating rate is 1℃ / min, and the temperature is held at 200℃ for 2 hours; from 200℃ to 400℃, the heating rate is 1℃ / min, and the temperature is held at 400℃ for 4 hours; 40℃ The furnace was heated from 0℃ to 480℃ at a rate of 1℃ / min, and held at 480℃ for 4 hours; from 480℃ to 600℃ at a rate of 1℃ / min, and held at 600℃ for 4 hours; from 600℃ to 800℃ at a rate of 1℃ / min, and held at 800℃ for 2 hours; from 800℃ to 840℃ at a rate of 1℃ / min, and held at 840℃ for 3 hours; from 840℃ to 1000℃ at a rate of 1℃ / min, and held at 1000℃ for 3 hours; and then cooled to room temperature with the furnace.

[0015] A further technical solution of the present invention is as follows: In step 2, the reaction temperature is 400-900℃, the heating rate is 1-10℃ / min, the reaction time is 10-20 hours, and the flow rate of the introduced argon-hydrogen gas is 200-300mL / min.

[0016] A further technical solution of the present invention is: in step 3, the reaction temperature is room temperature, the reaction time is 4 hours, and the corrosion reaction solution is a 2.5mM RuCl3 solution.

[0017] A further technical solution of the present invention is: in step 3, the Ru in the Ru-Ni(OH)2 / 3DP NiFe electrode is dispersed on the surface of the hydroxide in an atomic doping manner.

[0018] A further technical solution of the present invention is: in step 4, the reaction temperature is room temperature, the reaction time is 4 hours, and the corrosion reaction solution is 2.5mM FeCl3 solution.

[0019] A further technical solution of the present invention is: in step 4, the Fe atoms of the Fe-Ni(OH)2 / 3DP NiFe electrode are dispersed on the surface of the hydroxide in an atomic doping manner.

[0020] Beneficial effects

[0021] The beneficial effects of this invention are as follows: This invention discloses a method for preparing a high-efficiency water splitting electrode using a 3D-printed nickel-iron alloy with adjustable composition. By combining 3D printing technology (DLP) with a series of subsequent sintering processes, the alloy composition is controlled to ultimately achieve a three-dimensional porous, multi-level alloy electrode. The alloy electrode can be fabricated in one step using 3D printing technology. Compared to electroplating alloys on planar electrodes or metal foam electrodes, this method is simpler, and the 3D-printed electrode has a larger electrochemical active area and better catalytic effect due to its integral molding. Furthermore, compared to alloy electrodes electroplated on metal foam, the 3D electrode of this invention has a macroscopically ordered porous structure and a microscopic porous structure. While ensuring a sufficiently large electrochemical active area, its macroscopically ordered porous structure allows bubbles to escape rapidly under high current, thereby reducing the increase in overpotential caused by bubble adhesion. By adjusting the sintering process, the shrinkage of the three-dimensional electrode can be made uniform throughout, resulting in a flat alloy electrode. Simultaneously, the nickel and iron particles within the electrode can be better mixed and homogeneously, leading to a more uniformly distributed alloy electrode and thus better catalytic performance. Furthermore, compared to 3D-printed pure nickel electrodes, the 3D alloy nickel-iron electrode obtained through compositional control exhibits better OER catalytic performance, even at the cost of some HER catalytic effect, providing a feasible electrode fabrication solution for the currently slow OER kinetics.

[0022] The challenges of this invention lie firstly in the preparation of the alloy printing ink. This involves dissolving two different metal salts in an organic solution and adjusting the ball milling process to ensure uniform dispersion, facilitating subsequent printing. Secondly, it addresses the uneven shrinkage that can occur during sintering, leading to electrode bending or cracking. By adjusting the sintering process, the shrinkage of different parts of the sample is made consistent, resulting in a flat and complete three-dimensional electrode. Finally, in the reduction of the alloy oxide to the alloy, by refining the reduction parameters, the nickel and iron particles inside the electrode can be better mixed and uniformly, resulting in an alloy electrode with a uniform composition distribution, thus enhancing its catalytic effect.

[0023] This invention relates to 3D-printed nickel-iron alloy electrodes. The gyroid structure employed in this invention possesses high specific surface area and excellent structural stability. Furthermore, compared to active materials grown on a substrate, the 3D-printed nickel-iron alloy structure is formed by interconnected fine nickel-iron particles at the microscopic level, resulting in excellent mechanical stability. This ensures that the structure and material remain stable even under high current densities and the impact of numerous air bubbles. The alloy electrodes, etched with RuCl3 and FeCl3 solutions, are used as electrodes for HER and OER, respectively. Figure 6 Figures a and b show the linear sweep scalar volume (LSV) curves of HER and OER for different samples, respectively. As shown in the figure, in the hydrogen evolution reaction, when the current density is 500 mA cm⁻¹... -2 At this time, the overpotentials of 3DP NiFe and 3DP Ni were only 321.6 mV and 212.2 mV, respectively, while the overpotential of NF reached 411.7 mV. The lower overpotential indicates that 3DP NiFe has better catalytic activity. Meanwhile, the performance of the sample etched with RuCl3 was further improved due to the generation of metal hydroxide and Ru atom doping. The Ru-Ni(OH)2 / 3DP NiFe exhibited better catalytic activity at 500 mA cm⁻¹. -2 The overpotential reached 167.6 mV. The active material grown in situ on the electrode surface further reduced the overpotential required for the reaction, demonstrating the great potential of 3DP NiFe in practical applications of hydrogen evolution reaction (OER). On the other hand, the slow kinetics of oxygen evolution reaction (OER) has always been one of the reasons limiting efficient water electrolysis. Transition metals Ni and Fe are both highly efficient OER catalysts. In this invention, when the current density is 500 mA cm⁻¹... -2 At 500 mA, the overpotential of 3DP NiFe was only 330 mV, compared to 485 mV and 460 mV for NF and 3DP Ni, respectively. This superior OER catalytic performance stems from the synergistic effect of the highly efficient catalysts Ni and Fe. Furthermore, after etching with FeCl3, the in-situ growth of metal hydroxides on the electrode surface and the Fe doping further enhance its OER performance. -2 At 500 mA cm⁻¹, Fe-Ni(OH)₂ / 3DPNiFe -2 The overpotential reached 310 mV. The large electrochemical active surface area of ​​3DP NiFe allows for the loading of a large amount of active material, accelerating the reaction kinetics of OER and thus resulting in a lower overpotential. In summary, the advantages of 3DP NiFe are as follows:

[0024] (1) High specific surface area: The macroscopic three-dimensional structure enables it to load more active substances, and the microscopic porous structure gives it sufficient electrochemical active area, thus having more chemical active sites and improving catalytic activity.

[0025] (2) Better resolution: The metal salt electrode shrinks uniformly during sintering, reduction and subsequent processing, and the structure is kept intact, which effectively improves the fineness of the three-dimensional structure.

[0026] (3) Improved stability: The structure of 3D-printed nickel-iron alloy is formed by interconnected fine nickel-iron particles, giving it excellent mechanical stability. This ensures that it maintains structural and material stability even under high current density and the impact of numerous air bubbles.

[0027] (4) Bifunctional catalysis and stability: The presence of two transition metals enables the entire electrode to maintain sufficient stability during water electrolysis. At the same time, due to the synergistic effect between the two, it has excellent catalytic performance in both HER and OER. Attached Figure Description

[0028] Figure 1 This is a picture of a 3D-printed nickel-iron alloy electrode.

[0029] Figure 2 Microscopic morphology of 3D printed nickel-iron alloy electrode.

[0030] Figure 3 EDS energy dispersive spectroscopy analysis for 3D printed nickel-iron alloy electrodes.

[0031] Figure 4 (a) is a physical image of Ru-Ni(OH)2 / 3DP NiFe, and (b) is a microscopic morphology image of Ru-Ni(OH)2 / 3DP NiFe.

[0032] Figure 5 (a) is a physical image of Fe-Ni(OH)2 / 3DP NiFe, and (b) is a microscopic morphology image of Fe-Ni(OH)2 / 3DP NiFe.

[0033] Figure 6 In the middle section (a), the LSV curves for the hydrogen evolution reactions of NF,3DP Ni,3DP NiFe and Ru-Ni(OH)2 / 3DP NiFe are shown, and in the middle section (b), the LSV curves for the oxygen evolution reactions of NF,3DP Ni,3DP NiFe and Fe-Ni(OH)2 / 3DP NiFe are shown. Detailed Implementation

[0034] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0035] Example 1 (Comparative Example):

[0036] 3D nickel electrodes were fabricated using digital light processing (DLP) 3D printing technology. 56g of nickel sulfate, 3ml of L'Arquat CC 42NS, 22ml of hexanediol diacrylate, 3ml of ethoxylated trimethylolpropane triacrylate, and 0.5g of diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxide were mixed and stirred at room temperature for 24 hours to obtain a homogeneous nickel sulfate resin. This resin was then designed into a double-helix structure using DLP and printed. Finally, the structure was sintered in a muffle furnace at 1100℃ for 5 hours to obtain a nickel oxide template. The nickel oxide template was then reduced to metallic nickel by holding it at 600℃ for 10 hours using an argon-hydrogen mixed gas.

[0037] Example 2:

[0038] Step 1: Fabricate 3D nickel-iron alloy electrodes using digital light processing (DLP) 3D printing technology. A homogeneous resin is obtained by mixing 13.33g nickel sulfate, 6.67g ferrous sulfate, 2mL Variquat CC 42NS (generally, 20-30mL of ink is added to 2-4mL of Variquat CC), 10.56mL hexanediol diacrylate, 1.44mL ethoxylated trimethylolpropane triacrylate, and 0.24g diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxide at room temperature for 24 hours. Then, a double helix structure is designed and printed using DLP technology.

[0039] The sintering gradient temperatures were as follows: 20℃-85℃, heating rate 1℃ / min, holding at 85℃ for 2 hours; 85℃-200℃, heating rate 1℃ / min, holding at 200℃ for 2 hours; 200℃-400℃, heating rate 1℃ / min, holding at 400℃ for 4 hours; 400℃-480℃, heating rate 1℃ / min, holding at 480℃ for 4 hours; 480℃-600℃... The temperature was increased by 1℃ / min, and the temperature was held at 600℃ for 2 hours; then increased by 1℃ / min from 600℃ to 800℃, and held at 800℃ for 2 hours; then increased by 1℃ / min from 800℃ to 840℃, and held at 840℃ for 3 hours; then increased by 1℃ / min from 840℃ to 1000℃, and held at 1000℃ for 3 hours. The temperature was then lowered to room temperature in the furnace, and after sintering, nickel-iron oxide templates were obtained.

[0040] The sintering process involved in this step, after continuous improvement, aims to both volatilize organic matter from the three-dimensional electrode and decompose metal salts in the air to obtain metal oxide electrodes.

[0041] Step 2: Use an argon-hydrogen mixed gas to heat at 600℃ for ten hours to reduce the nickel-iron oxide template to an alloy nickel-iron substrate.

[0042] Reference Figure 1 , 2 As shown, compared to the smooth skeletal structure of metal foam, the microporous structure of 3D nickel-iron alloy provides a larger electrochemical active surface area, ensuring its highly efficient catalytic performance. EDS energy dispersive spectroscopy analysis revealed (… Figure 3 In the 3D nickel-iron alloy electrode, the Ni percentage content reached 77.6%, while the iron percentage content was 22.4%, indicating the successful preparation of the nickel-iron alloy. Compared with 3D-printed pure metallic nickel electrodes, the 3D alloy nickel-iron electrode obtained through compositional control exhibits better catalytic performance in OER (Organic Emission Reduction) despite sacrificing some HER (Heterochromic Emission) catalytic effect, providing a feasible electrode preparation solution for the current slow OER kinetics. Furthermore, the one-step preparation method eliminates the traditional cumbersome electroplating process, significantly improving preparation efficiency.

[0043] Step 3: Preparation of the electrode for the hydrogen evolution reaction. A simple corrosion-induced strategy was used to grow a metal hydroxide on a 3d nickel-iron substrate. 0.026 g of RuCl3·3H2O was dissolved in 50 mL of deionized water. After stirring thoroughly, the 3d nickel-iron electrode was immersed in the solution at room temperature for 4 hours. After immersion, the sample was rinsed with deionized water and dried in a vacuum drying oven to obtain the Ru-Ni(OH)2 / 3DP NiFe electrode for the hydrogen evolution reaction. (See attached image for reference.) Figure 4 As shown in (a), the specific morphological reference is... Figure 4 As shown in (b).

[0044] Step 4: Preparation of the electrode for the oxygen evolution reaction (OER). A simple corrosion-induced strategy was used to grow a metal hydroxide on a 3d nickel-iron substrate. 0.02 g of FeCl3·3H2O was dissolved in 50 mL of deionized water. After stirring thoroughly, the 3d nickel-iron electrode was immersed in the solution at room temperature for 4 hours. After immersion, the sample was rinsed with deionized water and dried in a vacuum drying oven to obtain the Fe-Ni(OH)2 / 3DP NiFe electrode for the OER. (See attached image for reference.) Figure 5 As shown in (a), the specific morphological reference is... Figure 5 As shown in (b).

[0045] The one-step etching process for in-situ growth of active materials simplifies the electrode fabrication process and also gives the electrode excellent stability. The in-situ grown active materials are not easily detached during catalysis and can maintain their catalytic effect without decay over long periods of time.

[0046] Reference Figure 6Figures (a) and (b) show the linear sweep scalar volume (LSV) curves of HER and OER for different samples, respectively. As shown in the figure, in the hydrogen evolution reaction, when the current density is 500 mA cm⁻¹... -2 At this time, the overpotentials of 3DP NiFe and 3DP Ni were only 321.6 mV and 212.2 mV, respectively, while the overpotential of NF reached 411.7 mV. The lower overpotential indicates that 3DP NiFe has better catalytic activity. Meanwhile, the performance of the sample etched with RuCl3 was further improved due to the generation of metal hydroxide and Ru atom doping. The Ru-Ni(OH)2 / 3DP NiFe exhibited better catalytic activity at 500 mA cm⁻¹. -2 The overpotential reached 167.6 mV. The active material grown in situ on the electrode surface further reduced the overpotential required for the reaction, demonstrating the great potential of 3DPNiFe in practical applications of hydrogen evolution reaction. On the other hand, oxygen evolution reaction (OER) has always been one of the reasons limiting efficient water electrolysis due to its slow kinetics. Transition metals Ni and Fe are both highly efficient OER catalysts. In this invention, when the current density is 500 mA cm⁻¹... -2 At 500 mA, the overpotential of 3DP NiFe was only 330 mV, compared to 485 mV and 460 mV for NF and 3DP Ni, respectively. This superior OER catalytic performance stems from the synergistic effect of the highly efficient catalysts Ni and Fe. Furthermore, after etching with FeCl3, the in-situ growth of metal hydroxides on the electrode surface and the Fe doping further enhance its OER performance. -2 At 500 mA cm⁻¹, Fe-Ni(OH)₂ / 3DP NiFe -2 The overpotential reached 310mV. The large electrochemical active area of ​​3DP NiFe allows it to load a large amount of active material, which accelerates the reaction kinetics of OER and thus gives it a lower overpotential.

[0047] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A method for preparing a high-efficiency water splitting electrode based on 3D printing of nickel-iron alloy, characterized in that: The high-efficiency water splitting electrode based on 3D printed nickel-iron alloy includes a Ru-Ni(OH)2 / 3DP NiFe electrode and a Fe-Ni(OH)2 / 3DP NiFe electrode, which are used for the hydrogen evolution reaction and oxygen evolution reaction in the water splitting reaction, respectively. The specific steps of the preparation method are as follows: Step 1: First, design a double-helix structure template; then, mix and stir the metal salt, Variquat CC 42 NS, hexanediol diacrylate, ethoxylated trimethylolpropane triacrylate, and diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxide to obtain a homogeneous metal salt resin; then, use digital light processing technology to print the metal salt resin into a double-helix structure; finally, sinter in air to obtain an alloy oxide electrode; Step 2: Heat the alloy oxide electrode obtained in Step 1 to the reaction temperature and keep it at a constant temperature. Introduce hydrogen and argon gas and carry out the reduction reaction at the set temperature. Cool the furnace to room temperature to obtain the alloy nickel-iron electrode. Step 3: Using the nickel-iron alloy electrode obtained in Step 2 as the substrate for in-situ growth of hydroxide, an electrolytic water electrode is prepared by a corrosion-induced strategy: the corrosion reaction solution is RuCl3 solution. After immersing the nickel-iron alloy electrode in RuCl3 solution at room temperature for 2-6 hours, the surface of the nickel-iron alloy electrode is etched to form metal hydroxide, which is used as the electrode for the HER reaction, namely Ru-Ni(OH)2 / 3DP NiFe. Step 4: Using the nickel-iron alloy electrode obtained in Step 2 as the substrate for in-situ growth of hydroxides, an electrolytic water electrode is prepared using a corrosion-induced strategy: The corrosion reaction solution is FeCl3 solution. After immersing the nickel-iron alloy electrode in FeCl3 solution at room temperature for 2-6 hours, the surface of the nickel-iron alloy electrode is etched to form metal hydroxides, which serve as the electrode for the OER reaction, namely Fe-Ni(OH)2 / 3DP NiFe.

2. The method for preparing a high-efficiency water splitting electrode based on 3D-printed nickel-iron alloy according to claim 1, characterized in that: In step 1, before preparing the printing ink, NiSO4·6H2O is placed in a muffle furnace for dehydration by air burning at a temperature of 100-200 ℃, with a heating rate of 3-5 ℃ / min and a dehydration time of 3-5 hours, to obtain the metal salt NiSO4; FeSO4·7H2O is placed in a tube furnace for dehydration at a temperature of 80-90 ℃, with a heating rate of 3-5 ℃ / min and a dehydration time of 1-5 hours. Argon gas is used for protection throughout the dehydration process, with a gas flow rate of 100-200 mL / min, to obtain the metal salt FeSO4.

3. The method for preparing a high-efficiency water splitting electrode based on 3D printed nickel-iron alloy according to claim 1, characterized in that: In step 1, 10-30 g of metal salt, 1-10 mL of Variquat CC 42 NS, 5-15 mL of hexanediol diacrylate, 1-10 mL of ethoxylated trimethylolpropane triacrylate, and 0.2-1 g of diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxychloride are mixed; the mixture is stirred at room temperature for 24 hours, and then ball-milled 1-5 times, each time for 60 minutes, with an interval of 5-15 minutes between each milling. The metal salt includes NiSO4 and FeSO4 in a mass ratio of 2:1; the volume ratio of hexanediol diacrylate to ethoxylated trimethylolpropane triacrylate is 22:3; and diphenyl-(2,4,6-trimethylbenzoyl)phosphorus oxychloride accounts for 2% of the total volume of the hexanediol diacrylate and ethoxylated trimethylolpropane triacrylate solutions.

4. The method for preparing a high-efficiency water splitting electrode based on 3D-printed nickel-iron alloy according to claim 1, characterized in that: In step 1, the sintering gradient temperatures are 85℃, 200℃, 400℃, 480℃, 600℃, 800℃, 840℃, and 1000℃; specifically, the following conditions apply: from 20℃ to 85℃, the heating rate is 1℃ / min, and the temperature is held at 85℃ for 2 hours; from 85℃ to 200℃, the heating rate is 1℃ / min, and the temperature is held at 200℃ for 2 hours; from 200℃ to 400℃, the heating rate is 1℃ / min, and the temperature is held at 400℃ for 4 hours; from 400℃ to 480℃, the heating rate is 1℃ / min, and the temperature is held at 480℃ for 4 hours; from 480℃ to 600℃, the heating rate is 1℃ / min, and the temperature is held at 600℃ for 4 hours; from 600℃ to 800℃, the heating rate is 1℃ / min, and the temperature is held at 800℃ for 1 hour. Hold at ℃ for 2 h; 800 ℃-840 ℃, heating rate of 1 ℃ / min, hold at 840 ℃ for 3 h; 840 ℃-1000 ℃, heating rate of 1 ℃ / min, hold at 1000 ℃ for 3 h; then cool to room temperature with the furnace.

5. The method for preparing a high-efficiency water splitting electrode based on 3D-printed nickel-iron alloy according to claim 1, characterized in that: In step 2, the reaction temperature is 400-900℃, the heating rate is 1-10℃ / min, the reaction time is 10-20 hours, and the flow rate of the introduced argon-hydrogen gas is 200-300 mL / min.

6. The method for preparing a high-efficiency water splitting electrode based on 3D-printed nickel-iron alloy according to claim 1, characterized in that: In step 3, the reaction temperature is room temperature, the reaction time is 4 hours, and the corrosion reaction solution is a 2.5 mM RuCl3 solution.

7. The method for preparing a high-efficiency water splitting electrode based on 3D-printed nickel-iron alloy according to claim 1, characterized in that: In step 3, the Ru in the Ru-Ni(OH)2 / 3DP NiFe electrode is dispersed on the hydroxide surface in an atomic doping manner.

8. The method for preparing a high-efficiency water splitting electrode based on 3D-printed nickel-iron alloy according to claim 2, characterized in that: In step 4, the reaction temperature is room temperature, the reaction time is 4 hours, and the corrosion reaction solution is a 2.5 mM FeCl3 solution.

9. The method for preparing a high-efficiency water splitting electrode based on 3D printed nickel-iron alloy according to claim 1, characterized in that: In step 4, the Fe atoms of the Fe-Ni(OH)2 / 3DP NiFe electrode are dispersed on the surface of the hydroxide in an atomic doping manner.

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