A method for preparing a trifunctional nickel-cobalt alloy electrode

Abstract

The present invention provides a preparation method of a trifunctional nickel-cobalt alloy electrode, belonging to the technical field of batteries. The preparation method specifically includes the following steps: printing a double-helical structure of NiCo resin by digital light processing; subjecting the double-helical structure to sintering treatment, cooling treatment and reduction treatment in sequence to obtain 3D NiCo; immersing the 3D NiCo in a methanol solution containing Co(NO3)2·6H2O and 2-methylimidazole, and obtaining Co-MOF / 3D-NiCo after aging treatment; subjecting the Co-MOF / 3D-NiCo to washing treatment, drying treatment and carbonization treatment in sequence to obtain a trifunctional nickel-cobalt alloy electrode. Compared with the prior art, the present invention has the following advantages: The present invention discloses the preparation of a trifunctional nickel-cobalt alloy electrode by 3D printing technology, with the multifunctional catalytic characteristics and synergistic effect of Ni-Co elements, and the growth of a Co-based metal-organic framework (MOF) precursor on the electrode and the subsequent anchoring of cobalt nanoparticles into a nickel-doped carbon microarray through a carbonization process, making it an efficient trifunctional catalytic electrode.

Description

Technical Field

[0001] The invention belongs to the technical field of batteries, and in particular relates to a method for preparing a tri-functional nickel-cobalt alloy electrode. Background Art

[0002] Faced with rapidly growing global energy demand and undeniable environmental pollution problems, achieving dual carbon goals and sustainable lifestyle transition has become a top priority. Solar-based renewable energy has been limited by intermittent availability, making the development, conversion, and storage of renewable energy a vital task. Solar-based renewable energy has been limited by intermittent availability, making the development, conversion, and storage of renewable energy a vital task. Integrating secondary batteries such as zinc-air batteries (ZABs) and water separation into a unified device has great potential as a solution, providing unprecedented opportunities for efficient conversion of renewable energy and clean hydrogen production. Oxygen reduction reaction (ORR), hydrogenation reaction (HER), and oxidation reaction (OER) are important half-reactions occurring in these energy systems. The kinetics of these reactions are slow, resulting in low reaction efficiency, so the development of versatile and durable catalysts is essential to achieve a carbon-free energy cycle system.

[0003] Traditionally, different catalysts are required for these three reactions due to their different reaction mechanisms, reaction conditions, and catalytic activities. These materials have unique electronic structures and surface active sites that can simultaneously catalyze HER, OER, and ORR, thereby improving the efficiency and performance of energy conversion and storage devices. Therefore, it is of great significance to design and fabricate low-cost catalyst materials with multifunctional catalytic capabilities. Transition metal-based electrodes have the potential to serve as efficient catalysts. Zhang, L., Zhu, J., Li, X., et al. Nurturing the Marriages of Single Atomswith Atomic Clusters and Nanoparticles for Better Heterogeneous Electrocatalysis. Interdiscip. Mater. 2022, 1:51–87. By coupling different elements, the surface properties and active sites of the electrode can be controlled, thereby achieving trifunctional catalysis of HER, OER, and ORR. Qu, J., Wang,Z., Gan, W., et al. Efficient Hydrogen Evolution on Antiperovskite CuNCo 3Nanowires by Mo Incorporation and its Trifunctionality for Zn Air Batteries and Overall Water Splitting. Small. 2023, 20, 2304541.

[0004] In addition, in trifunctional catalysis, structural design also plays an important role in precisely controlling bubble behavior and optimizing mass transfer conditions for catalytic reactions. By adopting precise structural regulation, ideal bubble dynamics can be obtained, providing optimized mass transfer conditions, thereby improving the overall catalytic performance. Especially in HER and OER, when bubbles attach to the electrode surface, they cover the active sites, hindering mass transfer between the electrode and the electrolyte, resulting in a significant reduction in the number of available active sites on the catalyst surface. On the other hand, in ORR, the participation of gas is necessary, which requires a certain degree of gas adsorption affinity to ensure sufficient adsorption of reactants. Therefore, it is imperative to design an electrode structure that can finely control the bubble dynamics to meet the specific needs of various reactions. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a trifunctional nickel-cobalt alloy electrode, and to achieve efficient water electrolysis by designing a multifunctional catalytic electrode. At the same time, the present invention proposes a 3D printing technology with high structural and material selectivity for preparing a trifunctional electrode integrating a battery electrode, a water electrolysis cathode and an anode.

[0006] The present invention provides a method for preparing a trifunctional nickel-cobalt alloy electrode, the preparation method specifically comprising the following steps:

[0007] S1, double helix structure of NiCo resin printed by digital light processing method;

[0008] S2, subjecting the double helix structure obtained in step S1 to sintering treatment, cooling treatment and reduction treatment in sequence to obtain 3D NiCo;

[0009] S3, immersing the 3D NiCo prepared in step S2 into a 3 ) 2 6H 2 O and 2-methylimidazole in methanol solution, and Co-MOF / 3D-NiCo was obtained after aging treatment;

[0010] S4, washing, drying and carbonizing the Co-MOF / 3D-NiCo obtained in step S3 to obtain a trifunctional nickel-cobalt alloy electrode;

[0011] The specific operations of step S1 are as follows:

[0012] S11, at a heating rate of 4-5℃ / min, NiSO 4 6H 2 O particles and CoSO 4 7H 2 O particles are heated to 140-160℃ and sintered for 4-6h to obtain NiSO 4 Particles and CoSO 4 Particles;

[0013] S12, after mixing the surfactant, 1,6-hexanediol diacrylate, ethoxylated trimethylolpropane triacrylate and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, adding the NiSO 4 Particles and CoSO 4 The particles are mixed and stirred to obtain NiCo resin;

[0014] S13, using the NiCo resin in step S12 as a printing material, and printing a double helix structure of the NiCo resin by a digital light processing method.

[0015] Compared with the prior art, the present invention has the following advantages: the present invention discloses the use of 3D printing technology to prepare a trifunctional nickel-cobalt alloy electrode, which uses the multifunctional catalytic properties and synergistic effect of the Ni-Co element, and grows a Co-based metal organic framework (MOF) precursor on the electrode and then anchors the cobalt nanoparticles to the nickel-doped carbon microarray through a carbonization process, making it a highly efficient trifunctional catalytic electrode. On this basis, the present invention firstly prepares NiSO 4 6H 2 O and CoSO 4 7H 2 O particles are sintered at a specific temperature to form purer NiSO 4 and CoSO 4 The particles ensure that the ratio of nickel and cobalt elements in the subsequent resin is more controllable. At the same time, digital light processing (DLP) 3D printing technology is used to manufacture the double helix structure, which allows the design of the electrode to be adjusted very finely. The addition of surfactants and specific types of acrylate monomers (such as 1,6-hexanediol diacrylate, ethoxylated trimethylolpropane triacrylate) and photoinitiators (diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide) not only improves the fluidity of the NiCo resin for easy printing, but also enhances the mechanical strength and durability of the cured structure.

[0016] In a possible implementation, in step S12, the surfactant is Variquat CC 42 NS.

[0017] Compared with the prior art, the present invention adopts the above surfactant mainly because Variquat CC 42 NS is an excellent cationic surfactant that can effectively improve NiSO 4 and CoSO 4 The dispersion of particles in the resin mixture helps ensure that the metal salt is evenly distributed in the resin, thereby ensuring that the final printed structure has good composition consistency; this surfactant can help different components (such as inorganic salts and organic resins) to be better compatible, reduce interfacial tension, and make the entire system more stable, which is convenient for subsequent 3D printing processes.

[0018] In one possible embodiment, NiSO 4 Particles and CoSO 4 The mass ratio of the particles is 1:1, and in the NiCo resin, the volume proportion of NiCo is 30-40%.

[0019] Compared with the prior art, the advantages of the above parameters in the present invention are: nickel (Ni) and cobalt (Co) both have good catalytic activity, but their catalytic efficiency for different reactions may be different. The design of a mass ratio of 1:1 helps to balance the catalytic properties of the two metals, so that the electrode can show high activity in a variety of electrochemical reactions. NiCo alloy provides a good conductive path, and a volume share of 30-40% ensures a sufficient conductive network, which is crucial to the performance of the electrode.

[0020] In step S13, the parameters of the digital light processing method are as follows: layer thickness is 0.045-0.055 mm, light intensity is 8.0-8.1 mW / cm 2 , the printing time is 1.1-1.3s, and the printing time for each layer is 0.4-0.6s.

[0021] Compared with the prior art, the advantages of the above parameters adopted by the present invention are: the layer thickness of 0.045-0.055mm means that a good balance can be achieved between accuracy and printing speed, and the light intensity of 8.0-8.1 mW / cm² is in a relatively low but effective range, which helps to ensure that the resin can be fully cured without over-curing or damaging the material properties due to excessive energy density. The overall printing time is 1.1-1.3 seconds, and the printing time per layer is 0.4-0.6 seconds, indicating that the printer can achieve fast printing while maintaining a high resolution.

[0022] In a possible implementation manner, in step S2, the specific process of the sintering treatment is:

[0023] First, in a muffle furnace, heat up to 95-105°C, 195-205°C, 445-455°C and 595-605°C at a heating rate of 2-3°C / min, and sinter at each temperature node for 2-3h;

[0024] Then, the temperature is continued to be raised to 800-900°C and 900-1100°C at a heating rate of 1-2°C / min, and sintered for 3-4h at each temperature node to obtain NiCo oxide for subsequent cooling and reduction treatments.

[0025] Compared with the prior art, the present invention adopts the above sintering process, and its advantages are as follows: by setting multiple temperature nodes and maintaining each temperature point for a certain time, this gradual heating method is conducive to the uniform transformation and stable formation of the internal structure of the material, which can avoid the internal stress concentration or uneven reaction of the material caused by rapid heating, thereby improving the quality of the product; at the same time, the use of different heating rates is crucial to ensure that the material can be heat treated in the expected manner. A lower heating rate is conducive to better diffusion and mixing between material components, as well as the growth and arrangement of grains, which is particularly beneficial for the formation of NiCo oxides with specific physical and chemical properties.

[0026] In a possible implementation, in step S2, the specific operation of the cooling treatment is: cooling to room temperature at a cooling rate of 2-3°C / min.

[0027] Compared with the prior art, the present invention adopts a slower cooling rate, which helps to reduce the thermal stress generated inside the material. If the cooling is too fast, it may cause a large temperature difference between the inside and outside of the material, thereby generating large thermal stress, which is detrimental to the structural integrity and performance of the material. By controlling the cooling rate, it is possible to ensure that the material is cooled evenly and reduce the risk of crack formation.

[0028] In a possible implementation manner, in step S2, the specific process of the reduction treatment is as follows: in a tube furnace, in an Ar / H atmosphere with a volume ratio of 90:10, 2 Under atmosphere, the temperature was raised to 650-660 °C at a heating rate of 2-3 °C / min and the reduction was carried out for 9-11 hours.

[0029] Compared with the prior art, the advantages of the reduction treatment process of the present invention are that the reaction can be carried out in a relatively closed and controllable environment by using a tubular furnace, which helps to accurately control the reaction conditions such as temperature and gas composition. 2=90:10) and flow rate can effectively manage the redox atmosphere during the reduction process, thereby ensuring that the NiCo oxide is fully but not excessively reduced; specifically, heating to the target temperature of 650-660℃ at a rate of 2-3℃ / min. This relatively slow heating rate can help the internal structure of the material gradually adapt to temperature changes and reduce damage caused by thermal stress. It is also conducive to the full contact and reaction between hydrogen and the surface or internal active sites of the material; 650-660℃ is a moderate reduction temperature. For most transition metal oxides, within this temperature range, oxygen atoms can be effectively removed to form metallic or low-valent compounds, and problems such as material melting and volatilization loss will not be caused by excessive temperature; maintaining at 650-660℃ for 9-11 hours, the long-term insulation provides enough time for the reduction reaction to be completed thoroughly, ensuring that all parts within the entire sample volume can undergo a complete reduction process.

[0030] In a possible embodiment, in step S3, the catalyst containing Co(NO 3 ) 2 6H 2 The methanol solution of O and 2-methylimidazole was prepared by the following preparation method: Co(NO 3 ) 2 6H 2 O and 2-methylimidazole were dissolved in methanol, and Co(NO 3 ) 2 6H 2 The mass ratio of O and 2-methylimidazole is (0.4-0.6):1.

[0031] In a possible implementation, in step S3, the parameters of the aging treatment are as follows: temperature is 24-27° C., and time is 3-5 h.

[0032] Compared with the prior art, the present invention adopts the above-mentioned aging treatment process, which has the following advantages: the selection of aging treatment close to room temperature (24-27°C) can avoid unnecessary changes or damage to the material structure due to excessively high temperature. Such mild conditions help to maintain the original physical and chemical properties of the material, while promoting the stability of the internal structure of the material. The 3-5 hour time window allows the components in the material to have enough time to reach equilibrium. During this period of time, the chemical reaction, phase change or other structural adjustment process in the material can be gradually completed, thereby forming a more stable final product.

[0033] In a possible implementation, in step S4, the solvents used for washing are deionized water and ethanol, and the number of washing times is ≥ 3 times.

[0034] In a possible implementation, in step S4, the parameters of the drying process are as follows: temperature is 50-70° C., and time is ≥12 h.

[0035] In a possible implementation manner, in step S4, the specific operation of the carbonization treatment is: heating to 490-520° C. at a heating rate of 2-3° C. / min, and carbonizing for 3-5 h.

[0036] Compared with the prior art, the advantage of the carbonization treatment in the present invention is that the temperature is slowly raised to 490-520°C at a rate of 2-3°C / min. This relatively mild heating method helps the internal structure of the material gradually adapt to temperature changes and reduces stress concentration or structural damage caused by rapid heating. 490-520°C is a moderate carbonization temperature range. Within this temperature range, the decomposition of organic matter can be effectively promoted to produce carbon, and interact with the base material (such as NiCo oxide) to form a composite material. At the same time, this temperature will not be too high, avoiding excessive volatilization or melting of metals or other components, and ensuring the integrity of the material.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] (1) The integration of functional structures can precisely control bubble behavior: The gradient design of the 3D-printed porous structure shows in situ analysis that when the small holes are facing upward, the number of bubbles is small but the diameter is large. Computational fluid dynamics analysis shows that when the gas flows from the small hole to the large hole, the maximum pressure occurs on the small hole side, and there is no significant pressure increase or speed decrease, indicating that the gas flow is unobstructed. The average gas velocity in the large hole reaches 7.69 m / s, which drops to 6.56 m / s in the small hole. The velocity in the area where the pore size changes is the largest, proving that the gas flows smoothly. This design effectively retains the gas, provides more reactants for ORR, accelerates the reaction, and improves the performance of ZABs. The gradient design of the porous structure optimizes the gas flow and provides an important improvement in battery performance;

[0039] (2) Excellent catalytic performance: Co-NC / 3D-NiCo performs well in HER performance, with an overpotential of only 59.5 mV at a current density of 100 mA / cm². In addition, the Cdl value of Co-NC / 3D-NiCo is as high as 51.2 mF / cm². In terms of OER performance, 100 mA / cm 2 The current density of Co-NC / 3D-NiCo is only 380 mV. In terms of ORR performance, ZABs with functional gradient pore structure have a high ORR performance at 153 mA / cm 2 73.5 mW / cm 2The power density can be sustained for more than 300 hours. These excellent performances are attributed to the formation of Ni-Co alloy, which not only provides additional active sites, but also enhances the diffusion of reactants on the catalyst surface and the reaction rate through the interaction between Ni and Co. At the same time, the multivalent nature of Ni and Co gives the material a rich electronic structure, which optimizes the adsorption and activation process of reactants, thereby further improving the performance of the catalytic reaction;

[0040] (3) Good stability: The material and structural design have significant activity and stability in water decomposition, maintaining stable operation for more than 500 hours at a current density of 500 mA / cm² and a voltage of 1.78 V, with a performance retention rate of 97.8%, showing excellent stability and potential in practical applications. 2 After 300 hours of charge-discharge testing, the battery showed negligible potential change, demonstrating its excellent durability;

[0041] (4) In summary, in this invention, we use 3D printing technology to construct a porous structure, aiming to achieve the integration of functional structures to precisely control the behavior of bubbles, thereby meeting the specific requirements of different catalytic reactions for bubble behavior. The innovative design of materials and structures is of great significance for promoting the research and development of efficient and versatile trifunctional electrodes, providing new prospects for the development, conversion and storage of sustainable energy in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 LSV curves of HER of 3D Ni, 3D Co, 3D NiCo, Co-NC / 3D NiCo and 20wt%Pt / C;

[0043] Figure 2 HER activity test result curves of 3D Ni, 3D Co, 3D NiCo, Co-NC / 3D NiCo and 20wt%Pt / C;

[0044] Figure 3 3D Ni, 3D Co, 3D NiCo, Co-NC / 3D NiCo and RuO 2 LSV curve of OER;

[0045] Figure 4 3D Ni, 3D Co, 3D NiCo, Co-NC / 3D NiCo and RuO 2 OER activity test result curve;

[0046] Figure 5The Co-NC / 3D-NiCo prepared in Example 4 was used as the working electrode in an electrolytic cell at 500 mA / cm 2 Long-term stability test result curve under ;

[0047] Figure 6 Polarization and power density curves of zinc-air batteries with gradient and macropores facing the zinc sheet;

[0048] Figure 7 Polarization and power density curves of zinc-air battery without gradient structure;

[0049] Figure 8 Polarization and power density curves of zinc-air battery with gradient and small holes facing the zinc sheet;

[0050] Fig. 9 The charge and discharge cycle curve of the zinc-air battery assembled using the Co-NC / 3D-NiCo prepared in Example 4. DETAILED DESCRIPTION

[0051] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation method and typical parameters of the present invention, and are not used to limit the parameter range described in the present invention. Reasonable changes derived therefrom are still within the scope of protection of the claims of the present invention.

[0052] It should be noted that the endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this article.

[0053] Unless otherwise defined, all terms, symbols and other scientific terms used herein are intended to have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. In some cases, terms with conventionally understood meanings are defined herein for the purpose of clarification or ease of reference, and such definitions herein should not be construed as indicating significant differences from conventional understandings in the art. The technical methods described or cited herein are generally well understood by those skilled in the art and are adopted by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents and instruments is carried out in accordance with the protocols and parameters given by the manufacturer.

[0054] The technical effects of the present invention are described below in conjunction with specific embodiments.

[0055] Example 1: This example provides a 3D NiCo, which is prepared by the following preparation method:

[0056] S1, at a heating rate of 5°C / min, NiSO 4 6H 2 O particles and CoSO 4 7H 2 O particles were heated to 150 °C and sintered for 5 h to obtain NiSO 4 Particles and CoSO 4 Particles;

[0057] S2, 4 mL Variquat CC 42 NS, 17.6 mL 1,6-hexanediol diacrylate, 2.4 mL ethoxylated trimethylolpropane triacrylate and 0.5 g diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide were mixed, and the sintered NiSO 4 Particles and CoSO 4 Particles, NiSO 4 Particles and CoSO 4 The mass of the particles is 20 g, and NiCo resin is obtained after mixing and stirring;

[0058] S3, using the NiCo resin in step S2 as a printing material, printing a double helix structure of the NiCo resin by a digital light processing method, the parameters of the digital light processing method are as follows: layer thickness is 0.05 mm, light intensity is 8.05 mW / cm 2 , printing time is 1.2s, and printing time per layer is 0.45s;

[0059] S4, the double helix structure obtained in step S3 is subjected to sintering treatment, cooling treatment and reduction treatment in sequence to obtain 3D NiCo, wherein the specific process of the sintering treatment is as follows:

[0060] First, in a muffle furnace, the temperature was raised to 100°C, 200°C, 450°C and 600°C in sequence at a heating rate of 2°C / min, and sintered at each temperature node for 2 h.

[0061] Then, the temperature was further increased to 840°C and 1000°C at a heating rate of 1°C / min, and NiCo oxide was obtained by sintering at each temperature node for 3 h.

[0062] The specific operation of the cooling treatment is: cooling to room temperature at a cooling rate of 2 °C / min;

[0063] The specific process of reduction treatment is as follows: in a tube furnace, in an Ar / H 2The temperature was raised to 650 °C at a rate of 2 °C / min under a molten-gas atmosphere and the reduction was carried out for 10 h.

[0064] Example 2: This example provides a 3D Ni, which is prepared by the following preparation method:

[0065] S1, at a heating rate of 5°C / min, NiSO 4 6H 2 O particles were heated to 150 °C and sintered for 5 h to obtain NiSO 4 Particles;

[0066] S2, 4 mL Variquat CC 42 NS, 17.6 mL 1,6-hexanediol diacrylate, 2.4 mL ethoxylated trimethylolpropane triacrylate and 0.5 g diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide were mixed, and 20 g NiSO 4 The particles are mixed and stirred to obtain Ni resin;

[0067] S3, using the Ni resin of step S2 as the printing material, printing the double helix structure of the Ni resin by digital light processing method, the parameters of the digital light processing method are as follows: layer thickness is 0.05 mm, light intensity is 8.05 mW / cm 2 , printing time is 1.2s, and printing time per layer is 0.5s;

[0068] S4, subjecting the double helix structure obtained in step S3 to sintering treatment, cooling treatment and reduction treatment in sequence to obtain 3D Ni, wherein the specific process of the sintering treatment is as follows:

[0069] First, in a muffle furnace, the temperature was raised to 100°C, 200°C, 450°C and 600°C in sequence at a heating rate of 2°C / min, and sintered at each temperature node for 2 h.

[0070] Then, the temperature was further increased to 840°C and 1000°C at a heating rate of 1°C / min, and NiCo oxide was obtained by sintering at each temperature node for 3 h.

[0071] The specific operation of the cooling treatment is: cooling to room temperature at a cooling rate of 2 °C / min;

[0072] The specific process of reduction treatment is as follows: in a tube furnace, in an Ar / H 2 The temperature was raised to 650 °C at a rate of 2 °C / min under a molten-gas atmosphere and the reduction was carried out for 10 h.

[0073] Example 3: This example provides a 3D Co, which is prepared by the following preparation method:

[0074] S1, at a heating rate of 5°C / min, CoSO 4 6H 2 O particles were heated to 150 °C and sintered for 5 h to obtain CoSO 4 Particles;

[0075] S2, 4 mL Variquat CC 42 NS, 17.6 mL 1,6-hexanediol diacrylate, 2.4 mL ethoxylated trimethylolpropane triacrylate and 0.5 g diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide were mixed, and 20 g CoSO sintered in step S1 was added. 4 The particles are mixed and stirred to obtain Co resin;

[0076] S3, using the Co resin in step S2 as the printing material, printing the double helix structure of the Co resin by a digital light processing method, the parameters of the digital light processing method are as follows: layer thickness is 0.05 mm, light intensity is 8.05 mW / cm 2 , printing time is 1.2s, and printing time per layer is 0.5s;

[0077] S4, the double helix structure obtained in step S3 is subjected to sintering treatment, cooling treatment and reduction treatment in sequence to obtain 3D Co, wherein the specific process of the sintering treatment is as follows:

[0078] First, in a muffle furnace, the temperature was raised to 100°C, 200°C, 450°C and 600°C in sequence at a heating rate of 2°C / min, and sintered at each temperature node for 2 h.

[0079] Then, the temperature was further increased to 840°C and 1000°C at a heating rate of 1°C / min, and NiCo oxide was obtained by sintering at each temperature node for 3 h.

[0080] The specific operation of the cooling treatment is: cooling to room temperature at a cooling rate of 2 °C / min;

[0081] The specific process of reduction treatment is as follows: in a tube furnace, in an Ar / H 2 The temperature was raised to 650 °C at a rate of 2 °C / min under a molten-gas atmosphere and the reduction was carried out for 10 h.

[0082] Example 4: This example provides a Co-NC / 3D-NiCo, which is prepared by the following preparation method:

[0083] S1, 1.33 g Co(NO 3 ) 2 6H 2O and 3 g 2-methylimidazole were dissolved in 50 mL methanol to prepare the Co(NO 3 ) 2 6H 2 O and 2-methylimidazole in methanol;

[0084] S2, immersing the 3D NiCo prepared in Example 1 into the Co(NO 3 ) 2 6H 2 O and 2-methylimidazole in methanol solution, and then aged at 25 °C for 4 h to obtain Co-MOF / 3D-NiCo;

[0085] S3. Wash the Co-MOF / 3D-NiCo obtained in step S2 with DI water and ethanol for three times, then dry it at 60°C for 12 h, and finally heat it to 500°C at a heating rate of 2°C / min and carbonize it for 4 h to obtain Co-NC / 3D-NiCo.

[0086] Example 5: This example provides a Co-NC / 3D-NiCo, which is different from Example 4 only in that in step S3 of this example, the carbonization temperature is 500°C and the time is 3 hours. The rest is the same as Example 4 and will not be repeated here.

[0087] Example 6: This example provides a Co-NC / 3D-NiCo, which is different from Example 4 only in that in step S3 of this example, the carbonization temperature is 500°C and the time is 5 hours. The rest is the same as Example 4 and will not be repeated here.

[0088] Example 7: This example provides a Co-NC / 3D-NiCo, which is different from Example 4 only in that in step S3 of this example, the carbonization temperature is 400°C and the time is 4 hours. The rest is the same as Example 4 and will not be repeated here.

[0089] The inventors conducted LSV tests on the electrochemical hydrogen evolution reaction of 3D NiCo prepared in Example 1, 3D Ni prepared in Example 2, 3D Co prepared in Example 3, Co-NC / 3D-NiCo prepared in Example 4, and 20wt% Pt / C. The test results are as follows: Figure 1 As shown, from Figure 1 It can be seen that 3D NiCo provides 100 mA cm -2The required overpotential is 77.5 mV, which is better than 3D Ni (203 mV), 3D Co (122.5 mV), and 20 wt% Pt / C (243.3 mV). The overpotential of Co NC / 3D NiCo at 100 mA cm-2 is reduced to 59.5 mV. Even at a high current density of 500 mA cm-2, the overpotential remains at a remarkably low level of 119.8 mV.

[0090] The inventors tested the HER activity of 3D NiCo prepared in Example 1, 3D Ni prepared in Example 2, 3D Co prepared in Example 3, Co-NC / 3D-NiCo prepared in Example 4, and 20wt% Pt / C. The test results are as follows: Figure 2 As shown, from Figure 2 It can be seen that the Tafel plot of Co NC / 3D NiCo is 48.9 mV dec. -1 , close to 20 wt% Pt / C (44.5 mV dec -1 ), lower than 3D Ni (130.6 mV dec -1 ) The formation of Ni-Co alloy provides additional active sites, and the interaction between Ni and Co enhances the diffusion of reactants on the catalyst surface and the reaction rate.

[0091] The inventors prepared 3D NiCo prepared in Example 1, 3D Ni prepared in Example 2, 3D Co prepared in Example 3, Co-NC / 3D-NiCo prepared in Example 4, and Ru / O 2 The LSV test of electrochemical oxygen evolution reaction was carried out, and the test results were as follows Figure 3 As shown, from Figure 3 It can be seen that in addition to the outstanding performance in HER, Co NC / 3D NiCo also exhibits excellent efficiency in catalyzing OER, which is attributed to the higher activity of oxidized Co species due to its highly active surface and the fast electron transfer ability of Co NCs.

[0092] The inventors prepared 3D NiCo prepared in Example 1, 3D Ni prepared in Example 2, 3D Co prepared in Example 3, Co-NC / 3D-NiCo prepared in Example 4, and Ru / O 2 OER activity test was performed, and the test results were as follows Figure 4 As shown, from Figure 4 It can be seen that in order to achieve 100mA cm -2 The overpotential of Co NC / 3D NiCo is only 380 mV, which is smaller than that of 3DNi (440 mV), 3D Co (430 mV), 3D NiCo (400 mV) and RuO2 (536 mV) overpotential.

[0093] The inventors used a platinum electrode as a counter electrode, a mercury oxide electrode as a reference electrode, and the Co-NC / 3D-NiCo prepared in Example 4 as a working electrode to configure an electrolytic cell. 2 The long-term stability test under Figure 5 As shown, from Figure 5 It can be seen that Co-NC / 3D-NiCo||Co-NC / 3D NiCo can operate stably for 500 hours with a performance retention rate of 97.8%, showing excellent stability and potential in practical applications.

[0094] The inventors tested zinc-air batteries with different structures and placements. Figure 6 The polarization and power density curves of the zinc sheet with gradient and macropores facing the zinc sheet are shown in Figure 2. Figure 6 It can be seen that the ZAB with functional gradient pore structure has a peak at 153 mAcm -2 73.5 mW cm -2 power density.

[0095] The inventors tested zinc-air batteries with different structures and placements. Figure 7 The polarization and power density curves without gradient structure are shown in Table 1. Figure 7 It can be seen that the ZAB without gradient pore structure has a peak value of 153 mA cm -2 46.7 mW cm -2 power density.

[0096] The inventors tested zinc-air batteries with different structures and placements. Figure 8 The polarization and power density curves of the zinc sheet with gradient and small holes facing the zinc sheet are shown in Figure 2. Figure 8 It can be seen that the ZAB with functional gradient pore structure has a peak at 153 mAcm -2 56.7 mW cm -2 power density.

[0097] The inventors assembled a zinc-air battery using the Co-NC / 3D-NiCo prepared in Example 4, and used the prepared electrode as an air cathode (the area exposed to the electrolyte and air was about 0.8 cm 2 ), polished Zn foil as anode and 6 M KOH and 0.2 M Zn (CH 3 COO 2 The mixed solution was used as electrolyte to assemble aqueous ZAB. At room temperature, the LAND test system was used to measure the -2The constant current charge and discharge measurements were carried out under the condition of 10 minutes of discharge and 10 minutes of charge. The test results are shown in the figure. Fig. 9 As shown, Fig. 9 The charge and discharge cycle curves of Co-NC / 3D-NiCo zinc-air battery are shown in Figure 2. Fig. 9 It can be seen that: at 5mAcm -2 After 300 hours of charge and discharge testing, the battery's potential change was negligible, demonstrating its excellent durability.

[0098] Although the disclosure is disclosed as above, the protection scope of the disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the disclosure, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A method for preparing a trifunctional nickel-cobalt alloy electrode, characterized in that: The preparation method specifically comprises the following steps: S1, double helix structure of NiCo resin printed by digital light processing method; S2, subjecting the double helix structure obtained in step S1 to sintering, cooling and reducing treatments in sequence to obtain 3DNiCo; S3, immersing the 3D NiCo prepared in step S2 in a methanol solution containing Co(NO3)2·6H2O and 2-methylimidazole, and obtaining Co-MOF / 3D-NiCo after aging treatment; S4, washing, drying and carbonizing the Co-MOF / 3D-NiCo obtained in step S3 to obtain a trifunctional nickel-cobalt alloy electrode; The specific operations of step S1 are as follows: S11, heating the NiSO4·6H2O particles and the CoSO4·7H2O particles to 140-160°C at a heating rate of 4-5°C / min and sintering for 4-6h to obtain NiSO4 particles and CoSO4 particles; S12, after mixing a surfactant, 1,6-hexanediol diacrylate, ethoxylated trimethylolpropane triacrylate and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, adding the NiSO4 particles and CoSO4 particles sintered in step S11, and mixing and stirring to obtain a NiCo resin; S13, using the NiCo resin in step S12 as a printing material, and printing a double helix structure of the NiCo resin by a digital light processing method.

2. The method for preparing a trifunctional nickel-cobalt alloy electrode according to claim 1, characterized in that: In the step S12, the surfactant is Variquat CC 42 NS.

3. The method for preparing a trifunctional nickel-cobalt alloy electrode according to claim 1, characterized in that: In step S13, the parameters of the digital light processing method are as follows: layer thickness is 0.045-0.055 mm, light intensity is 8.0-8.1 mW / cm 2 , the printing time is 1.1-1.3s, and the printing time for each layer is 0.4-0.6s.

4. The method for preparing a trifunctional nickel-cobalt alloy electrode according to claim 1, characterized in that: In step S2, the specific process of sintering is as follows: First, in a muffle furnace, heat up to 95-105°C, 195-205°C, 445-455°C and 595-605°C at a heating rate of 2-3°C / min, and sinter at each temperature node for 2-3h; Then, the temperature is continued to be raised to 840°C and 1000°C in sequence at a heating rate of 1-2°C / min, and sintered for 3-4h at each temperature node to obtain NiCo oxide for subsequent cooling and reduction treatments.

5. The method for preparing a trifunctional nickel-cobalt alloy electrode according to claim 1, characterized in that: In step S2, the specific operation of the cooling treatment is: cooling to room temperature at a cooling rate of 2-3 °C / min; And / or, in step S2, the specific process of the reduction treatment is: in a tube furnace, in an Ar / H2 atmosphere with a volume ratio of 90:10, heating to 650-660°C at a heating rate of 2-3°C / min, and reducing for 9-11 h.

6. The method for preparing a trifunctional nickel-cobalt alloy electrode according to claim 1, characterized in that: In step S3, the methanol solution containing Co(NO3)2·6H2O and 2-methylimidazole is prepared by the following preparation method: Co(NO3)2·6H2O and 2-methylimidazole are dissolved in methanol, and the mass ratio of Co(NO3)2·6H2O to 2-methylimidazole is (0.4-0.6):

1.

7. The method for preparing a trifunctional nickel-cobalt alloy electrode according to claim 1, characterized in that: In step S3, the parameters of the aging treatment are as follows: temperature is 24-27° C., and time is 3-5 hours.

8. The method for preparing a trifunctional nickel-cobalt alloy electrode according to claim 1, characterized in that: In step S4, the solvents used in the washing process are deionized water and ethanol, and the number of washing times is ≥ 3 times; In step S4, the parameters of the drying process are as follows: temperature is 50-70° C., and time is ≥12 h.

9. The method for preparing a trifunctional nickel-cobalt alloy electrode according to claim 1, characterized in that: In step S4, the specific operation of the carbonization treatment is: heating to 490-520°C at a heating rate of 2-3°C / min, and carbonizing for 3-5 hours.

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