A method for rapidly constructing a nano-cone supported nanosheet electrocatalyst
The ZnCo2O4@Co3O4 nanoconical supported nanosheet electrocatalyst was prepared by combining hydrothermal and electrodeposition methods, which solved the problems of high cost, unreasonable structure and poor stability of existing electrocatalysts, and achieved high efficiency and stability in electrocatalysis.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHENYANG MEDICAL COLLEGE
- Filing Date
- 2022-12-26
- Publication Date
- 2026-05-22
AI Technical Summary
Existing HER and OER electrocatalysts are expensive, have unreasonable structural designs, low utilization of active components, and poor stability, making it difficult to work stably in complex ionic environments, especially in seawater.
A ZnCo2O4@Co3O4 nanoconical supported nanosheet electrocatalyst was prepared on a nickel foam substrate using a combination of hydrothermal and electrodeposition methods. The core-shell structure was formed through electrochemical deposition and thermal treatment, which prevented the material structure from collapsing and provided multiple reactive sites.
It improves the electron transport characteristics and active site exposure of the electrocatalyst, reduces the overpotential, enhances the stability and efficiency of the electrocatalytic reaction, and exhibits excellent electrochemical performance.
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Figure CN116065185B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of hydrogen electrocatalyst preparation, specifically a method for rapidly constructing nanoconical supported nanosheet electrocatalysts, which can be used in water splitting for hydrogen production, carbon dioxide reduction, and oxygen reduction and other related fields. Background Technology
[0002] Currently, hydrogen energy is a rapidly developing new energy source that has attracted much attention in recent years. It boasts advantages such as zero pollution, zero carbon emissions, high energy density (exceeding 140 MJ / kg, three times that of fossil fuels and 100 times that of lithium batteries), abundant reserves (raw materials include water and natural gas), storability, and renewability. In recent years, the demand for hydrogen energy has been increasing, and the hydrogen energy industry has become a strategic choice for developed countries such as the United States, Germany, and Japan. However, current hydrogen production processes based on natural gas and coal, both domestically and internationally, suffer from drawbacks such as limited fossil fuel reserves, high pollution, and high energy consumption, making it difficult to meet the future demand for clean hydrogen energy. Hydrogen production through water electrolysis can utilize abundant inland photovoltaic, wind, nuclear, and hydropower resources, as well as abundant coastal seawater resources, to achieve efficient and low-pollution hydrogen production. However, it has long been limited by precious metal electrocatalysts such as platinum, resulting in high costs and hindering large-scale commercial application. To date, the most effective electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are Pt-based, Ru-based, and Ir-based materials with high exchange current densities.
[0003] Therefore, developing novel and efficient hydrogen production electrocatalysts has become the key to the practical application and commercialization of hydrogen production through water electrolysis. The novel electrocatalysts reported so far can be roughly classified into two research directions: (1) novel compound electrocatalysts based on highly catalytically active non-precious metal elements, such as transition metals, metal-organic frameworks and their nitrogen, phosphorus, sulfur and boron compounds; (2) designing and synthesizing catalyst structures with high specific surface area, high diffusion performance and high catalytic active site loading, such as two-dimensional planar material catalysts such as molybdenum disulfide and graphene, and porous catalysts such as carbon nanotubes. However, the current research on HER electrocatalysts still faces the following problems and challenges, such as: (1) the cost of catalysts using materials such as molybdenum, ruthenium, rhodium and carbon nanotubes needs to be reduced, and the preparation involves pollution; (2) the catalyst structure design is unreasonable, the utilization rate of active components is low, and there is still little research on three-dimensional electrocatalysts with high mass transfer and diffusion performance designed using nanoengineering technology; (3) the acid and alkaline environment requirements are harsh, the corrosion resistance, stability and regeneration, electrochemical performance is poor, energy consumption is high, and it is difficult to work stably in the complex ionic environment of seawater. Transition metals are abundant and inexpensive, and their derivatives, phosphides, have been extensively studied. In recent years, numerous studies have shown that non-noble metal-based catalysts possess unique electronic structures, excellent catalytic performance, abundant reserves, and ease of preparation and control, significantly reducing production costs and difficulties, thus demonstrating promising application prospects. Among them, ZnCo2O4, due to its excellent electrocatalytic performance, modified spinel structure, and higher conductivity than single-metal oxides, exhibits good electron transfer capabilities, effectively promoting catalytic reaction efficiency, making it one of the most popular research materials. Furthermore, ZnCo2O4 nanostructures can also serve as catalysts for water electrolysis. Unlike other MCo2O4 (M = Ni, Mn, Fe) oxides, it possesses superior electrocatalytic performance. This is because in spinel ZnCo2O4, Co... 3+ Located at the octahedral position of the electrocatalytic active center, while Co 2+ It is located in a tetrahedral position. And Zn 2+ Intervention does not affect Co 3+ At the catalytic active site, it simply replaced Co. 2+ However, ZnCo2O4 materials suffer from a problem where their volume undergoes drastic changes during the reaction, leading to powdery phenomena during use and affecting stability. Therefore, it is necessary to design reasonable preparation methods to improve the material. Summary of the Invention
[0004] The technical problem to be solved by this invention is a method for rapidly preparing a nanoconical supported nanosheet electrocatalyst, which can solve problems such as material uniformity, electron transport characteristics, and exposure of active sites.
[0005] This invention is implemented as follows:
[0006] A method for rapidly constructing nanoconical supported nanosheet electrocatalysts, comprising the following steps:
[0007] 1) Pretreatment of nickel foam: ultrasonic treatment with alcohol and deionized water, and finally drying the nickel foam in a vacuum drying oven.
[0008] 2) Dissolve 0.5-1.0g cobalt nitrate, 0.2-0.5g zinc nitrate, 0.05-0.1g ammonium fluoride, and 0.3-0.5g urea in 40-80ml of water and stir for 20-40 minutes; then transfer the above solution into a reaction vessel and keep it at 120℃ for 5-8 hours; allow it to cool naturally to room temperature, wash it 2-4 times with anhydrous ethanol and deionized water, and dry the prepared sample at 60℃ for 12 hours; finally, calcine the prepared sample at 300-400℃ for 1-3 hours to obtain the ZnCo2O4 sample;
[0009] 3) Using a 0-0.5 mol / L cobalt nitrate solution as the electrolyte, an electrochemical deposition reaction was carried out using a ZnCo2O4 sample grown on nickel foam as the working electrode, Ag / AgCl as the reference electrode, and Pt as the counter electrode. The deposition was carried out at a potential of -0.5-1.5 V for 5-25 minutes. The sample was washed and dried, and then calcined in air at 300-400℃ for 1-3 hours to obtain nanoconical supported nanosheets of ZnCo2O4@Co3O4.
[0010] Furthermore, the size of the nickel foam is 4cm x 4cm, and the nickel foam is kept vertical throughout the preparation process.
[0011] Further, in step 2), 0.8 g of cobalt nitrate, 0.4 g of zinc nitrate, 0.1 g of ammonium fluoride, and 0.3 g of urea are dissolved in 60 ml of water. The solution is then transferred to a reaction vessel and kept at 120°C for 5-8 hours. After natural cooling to room temperature, the sample is washed 2-4 times with anhydrous ethanol and deionized water. The prepared sample is then dried at 60°C for 12 hours. The prepared sample is further calcined at 300-400°C for 1-3 hours to obtain a ZnCo2O4 sample. In step 3), Co3O4 is prepared using a 0-0.5 mol / L cobalt nitrate solution as the electrolyte and by utilizing the electrochemical product method. Compared with the prior art, the advantages of this invention are:
[0012] The purpose of this invention is to rapidly synthesize heterogeneous electrocatalysts with unique structures. The technical problem this invention aims to solve is a method for rapidly synthesizing nanocones as a framework to support nanosheet electrocatalysts.
[0013] This invention employs an integrated method to prepare high-performance electrocatalysts, which effectively avoids the use of binders. Simultaneously, the integrated electrode material effectively prevents structural collapse, which could lead to poor activity and stability.
[0014] Since the water-splitting performance of a material is closely related to the morphology of the prepared sample, and precisely controlling the morphology of the electrode material is a major obstacle in its preparation, achieving a controllable morphology is difficult due to the complexity of the reaction process. Furthermore, the morphology of the material significantly affects its water-splitting hydrogen production properties. However, this invention, by modifying the synthesis method, can prepare the desired high-performance heterostructure electrocatalyst more rapidly than traditional methods. Results show that the prepared sample exhibits a nanosheet structure covering the surface of a nanocone. This nanocone structure possesses good structural stability and provides numerous reactive sites during the electrochemical reaction, significantly reducing the overpotential of the electrocatalytic reaction. Moreover, the synthesis method also has a significant impact on the material's performance; selecting an appropriate method is crucial for preparing high-performance electrocatalysts. A common method for preparing heterostructures is to first prepare ZnCo2O4 electrode material via hydrothermal methods, and then prepare Co3O4 via secondary hydrothermal methods. However, this method is time-consuming, involves many reaction steps, and is cumbersome. The complex reaction process leads to many uncertainties in the prepared material. To avoid this phenomenon, we used both hydrothermal and electrodeposition methods to prepare ZnCo2O4@Co3O4 electrode materials. Electrochemical performance tests showed that the electrocatalyst prepared by this rapid reaction can ensure the phase purity of the material. Furthermore, the electrode prepared by combining hydrothermal and electrodeposition exhibits a unique morphology that facilitates accelerated charge transfer and provides multiple reactive sites to a certain extent, thereby significantly increasing the number of reactive sites and reducing the overpotential of the reaction.
[0015] This invention synthesizes ZnCo2O4 and ZnCo2O4@Co3O4 as water splitting electrocatalysts on nickel foam substrates using a simple hydrothermal-electrodeposition and subsequent heat treatment strategy, achieving an OER current density of up to 50 mA cm⁻¹. -2 The overpotential is 278 mV, and the Tafel slope is 67.6 mV dec. -1 The overpotential of HER was 166 mV, and the Tafel slope was 106.4 mV dec. -1The concentrations of these parameters are higher than those of the monomers ZnCo2O4 and Co3O4. Furthermore, the ZnCo2O4@Co3O4 sample also exhibits a battery voltage of 1.67V and an ultra-long durability of 50 hours. This suggests that heterogeneous structures can achieve structural optimization of ZnCo2O4 electrocatalysts and improve their corresponding electrochemical performance.
[0016] This invention alters the internal electronic structure by doping with metal elements or using a core-shell structure, significantly improving the cycling stability of ZnCo2O4 samples by suppressing volume changes. The use of Co ions enhances conductivity and catalytic activity. Furthermore, combining the advantages of ZnCo2O4 and Co3O4, this invention prepares highly efficient ZnCo2O4@Co3O4 nanowires for energy conversion applications. Attached Figure Description
[0017] Figure 1 This is an X-ray diffraction pattern of a nanocone-supported nanosheet electrocatalyst for rapid construction according to the present invention;
[0018] Figure 2 This is a scanning electron microscope image of a nanocone-supported nanosheet electrocatalyst for rapid construction according to the present invention.
[0019] Figure 3 This is a scanning electron microscope image of a nanocone-supported nanosheet electrocatalyst for rapid construction according to the present invention.
[0020] Figure 4 The present invention provides a hydrogen evolution polarization curve for a rapidly constructed nanoconical supported nanosheet electrocatalyst.
[0021] Figure 5 Cyclic stability curve of a rapidly constructed nanoconical supported nanosheet electrocatalyst according to the present invention;
[0022] Figure 6 The present invention provides a hydrogen evolution polarization curve for a rapidly constructed nanoconical supported nanosheet electrocatalyst.
[0023] Figure 7 The present invention provides a complete water splitting polarization curve for a rapidly constructed nanoconical supported nanosheet electrocatalyst.
[0024] Figure 8 Cyclic stability curve of a rapidly constructed nanoconical supported nanosheet electrocatalyst according to the present invention; Detailed Implementation
[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0026] Example 1
[0027] A method for rapidly constructing nanoconical supported nanosheet electrocatalysts, the method comprising:
[0028] 1) Pre-treat the nickel foam by sonicating it in deionized water for half an hour, then sonicating it in alcohol for half an hour, repeating this process three times, and finally drying the nickel foam in a vacuum drying oven.
[0029] 2) Dissolve 0.5g cobalt nitrate, 0.2g zinc nitrate, 0.05g ammonium fluoride, and 0.3g urea in 50ml of water and stir for 20 minutes. Then transfer the solution to an 80ml reactor and keep it at 120℃ for 6 hours. After it cools naturally to room temperature, wash it five times with anhydrous ethanol and deionized water. Next, dry the prepared sample (keeping it at 60℃ for 12 hours). Finally, calcine the prepared sample at 300℃ for 1-3 hours to obtain ZnCo2O4 sample.
[0030] 3) Next, a 0.2 mol / L cobalt nitrate solution was used as the electrolyte. The ZnCo₂O₄ sample grown on nickel foam was used as the working electrode. Ag / AgCl was used as the reference electrode, and Pt was used as the counter electrode for electrochemical deposition at a deposition potential of -0.9 V for 15 minutes. Finally, the sample was washed and dried. Finally, calcination in air at 300 °C for 1.5 h yielded nanoconical supported nanosheets of ZnCo₂O₄@Co₃O₄.
[0031] All reagents used in the entire experiment were of analytical grade, with a purity of 99.99%.
[0032] The nickel foam measures 4cm x 4cm, and during the preparation process, it is ensured that the nickel foam is perpendicular to the bottom of the reactor.
[0033] Example 2
[0034] Unlike Example 1), 1.0 g cobalt nitrate, 0.5 g zinc nitrate, 0.1 g ammonium fluoride, and 0.6 g urea were dissolved in 70 ml of water and stirred for 40 minutes. The solution was then transferred to an 80 ml reactor and kept at 120°C for 7 hours. After naturally cooling to room temperature, the sample was washed five times with anhydrous ethanol and deionized water. The prepared sample was then dried (keeping it at 60°C for 12 hours). Finally, the prepared sample was further calcined at 300°C for 2 hours to obtain a ZnCo₂O₄ sample.
[0035] 3) Next, a 0.5 mol / L cobalt nitrate solution was used as the electrolyte. The ZnCo₂O₄ sample grown on nickel foam was used as the working electrode. Ag / AgCl was used as the reference electrode, and Pt was used as the counter electrode for electrochemical deposition at a deposition potential of -0.9 V for 20 minutes. Finally, the sample was washed and dried. Finally, calcination in air at 300 °C for 1.5 h yielded nanoconical supported nanosheets of ZnCo₂O₄@Co₃O₄.
[0036] Example 3
[0037] Unlike Example 1), 0.8 g cobalt nitrate, 0.4 g zinc nitrate, 0.1 g ammonium fluoride, and 0.3 g urea were dissolved in 60 ml of water and stirred for 40 minutes. The solution was then transferred to an 80 ml reactor and kept at 120°C for 7 hours. After naturally cooling to room temperature, the sample was washed five times with anhydrous ethanol and deionized water. The prepared sample was then dried (keeping it at 60°C for 12 hours). Finally, the prepared sample was further calcined at 300°C for 2 hours to obtain a ZnCo₂O₄ sample.
[0038] 3) Next, a 0.5 mol / L cobalt nitrate solution was used as the electrolyte. The ZnCo₂O₄ sample grown on nickel foam was used as the working electrode. Ag / AgCl was used as the reference electrode, and Pt was used as the counter electrode for electrochemical deposition at a deposition potential of -0.9 V for 20 minutes. Finally, the sample was washed and dried. Finally, calcination in air at 300 °C for 1.5 h yielded nanoconical supported nanosheets of ZnCo₂O₄@Co₃O₄.
[0039] The finished product obtained in Example 1 was subjected to X-ray inspection, and the results are shown in the figure. Figure 1 The XRD pattern of the existing composite material shows that both ZnCo2O4 and Co3O4 phases can be observed simultaneously. This indicates that the ZnCo2O4@Co3O4 product has been successfully prepared on Ni foam.
[0040] See Figure 2 The ZnCo2O4@Co3O4 sample maintained the morphology of two single samples, namely the structure of nanocones and nanosheets, and the convoluted nanosheets wrapped around the nanocones to form a core-shell structure resembling leaf veins.
[0041] See Figure 3 This is a scanning electron microscope image of the electrocatalyst prepared in this invention;
[0042] See Figure 4 The hydrogen evolution polarization curves for the heterostructure electrode material show that at a current density of 10 mA cm⁻¹ -2At that time, the overpotential of the ZnCo2O4@Co3O4 electrode (166mV) was lower than that of the single ZnCo2O4 (224mV), Co3O4 (198mV) and nickel foam (391mV) samples.
[0043] See the cycle stability test. Figure 5 It can be observed that the prepared electrocatalyst exhibits good cycle stability.
[0044] Figure 6 The figures show the oxygen evolution polarization curves of the heterostructure electrode materials, and the LSV curves comparing the IrO2 catalyst and the nickel foam catalyst. It can be seen that the electrocatalytic performance of ZnCo2O4@Co3O4 is significantly better than that of the ZnCo2O4 and Co3O4 samples, even surpassing the commercial IrO2 catalyst at high current densities, while the effect of nickel foam on the electrocatalytic performance is negligible.
[0045] Figure 7 This study demonstrates the complete water splitting of heterostructured electrode materials. A comparison of water splitting capabilities was observed, with the ZnCo2O4@Co3O4 exhibiting a significantly lower cell voltage than the ZnCo2O4 electrocatalyst, indicating a higher current density. The ZnCo2O4@Co3O4 electrocatalyst exhibited a cell voltage of only 1.67 V (50 mA cm⁻¹). -2 The battery voltages for ZnCo2O4 and Co3O4 are 1.82V (1.79V).
[0046] Long-term stability test of pyrolyzed water, such as Figure 8 As shown, the catalyst's current value remained constant during continuous water splitting, demonstrating good long-term stability. The composite catalyst exhibited stability even at high current densities.
[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for rapidly constructing nanoconical supported nanosheet electrocatalysts, characterized in that, The method includes: 1) Pretreatment of nickel foam: ultrasonic treatment with alcohol and deionized water, and finally drying the nickel foam in a vacuum drying oven; 2) Dissolve 0.5-1.0 g cobalt nitrate, 0.2-0.5 g zinc nitrate, 0.05-0.1 g ammonium fluoride, and 0.3-0.5 g urea in 40-80 ml of water and stir for 20-40 minutes; then transfer the above solution into a reaction vessel and keep it at 120℃ for 5-8 hours; allow it to cool naturally to room temperature, wash it 2-4 times with anhydrous ethanol and deionized water, and dry the prepared sample at 60℃ for 12 hours; finally, calcine the prepared sample at 300-400℃ for 1-3 hours to obtain the ZnCo2O4 sample; 3) Using cobalt nitrate solution as the electrolyte with a concentration of 0.2-0.5 mol / L, an electrochemical deposition reaction was carried out using a ZnCo2O4 sample grown on nickel foam as the working electrode, Ag / AgCl as the reference electrode, and Pt as the counter electrode. The electrodeposition potential was between -0.5V and -1.5V for 5-25 minutes. The sample was washed and dried, and then calcined in air at 300-400°C for 1-3 h to obtain nanoconical supported nanosheets of ZnCo2O4@Co3O4.
2. The method for rapidly constructing nanoconical supported nanosheet electrocatalysts according to claim 1, characterized in that, The nickel foam measures 4 cm x 4 cm and remains vertical throughout the preparation process.
3. The method for preparing a rapidly constructed nanoconical supported nanosheet electrocatalyst according to claim 1, characterized in that, Step 2) Dissolve 0.8 g cobalt nitrate, 0.4 g zinc nitrate, 0.1 g ammonium fluoride, and 0.3 g urea in 60 ml of water, then transfer the solution to a reaction vessel and keep it at 120°C for 5-8 h. Cool naturally to room temperature, wash with anhydrous ethanol and deionized water 2-4 times, and dry the prepared sample at 60°C for 12 h. Further calcine the prepared sample at 300-400°C for 1-3 h to obtain ZnCo2O4 sample. Step 3) Select cobalt nitrate solution as electrolyte, with a cobalt nitrate solution concentration of 0.2-0.5 mol / L, and prepare Co3O4 by electrochemical deposition.