Preparation method of Co-based oxide nanosheets based on oxygen vacancy regulation reaction mechanism and its application in acidic oxygen evolution reaction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-26
- Publication Date
- 2026-08-14
AI Technical Summary
[0005]本发明的目的是要解决电催化水析氧反应的效率有待提高以及成本较高的问题，而提供一种基于氧空位调控的六边形Co基氧化物纳米片制备方法及其酸性析氧应用，能有效提高贵金属的使用率降低成本，触发了LOM机制，提高了催化剂的催化性能进而提升PEMWE的产氢效率
[0016]1、本发明催化剂Ru-Co3O4-x通过简单的方法增加氧空位数量触发LOM机制，绕开传统AEM机制的限制关系，降低反应能垒，提升催化性能。其中增加氧空位的方法是指使用硼氢化钠溶液对催化剂前驱体进行浸泡以使晶格氧析出，此处硼氢化钠浸泡的作用不同于现有电解水催化剂通过氧空位增加活性位点的作用，本发明通过氧空位数量的增加以触发LOM机制。
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrocatalytic water splitting oxygen evolution reaction, specifically relating to a method for preparing hexagonal Co-based oxide nanosheets based on oxygen vacancy regulation and its application in acidic oxygen evolution. Background Technology
[0002] The search for a green and pollution-free clean energy source plays a crucial role in the future development of humankind. Currently, various renewable resources are being developed and utilized, among which hydrogen, with its high calorific value and clean products, has attracted significant attention. Current methods for obtaining hydrogen include natural gas pyrolysis, natural gas reforming, lignite gasification, and electrolysis. Water electrolysis offers advantages such as high-purity hydrogen and a simple process; however, its efficiency remains a problem to be solved. Water electrolysis consists of two half-reactions. The oxygen evolution reaction (OER) at the anode involves a four-electron transfer process, which is slow and determines the overall reaction rate. Furthermore, the proton exchange membrane electrolyzer (PEMWE) is a novel type of electrolyzer, more suitable for future hydrogen production applications than traditional alkaline water electrolysis (AWE). However, the acidic reaction environment of PEMWE leads to insufficient anode catalyst activity and poor stability, making the already slow OER reaction even more difficult. Therefore, developing a high-performance and stable anode catalyst is of great significance for the widespread application of PEMWE in water electrolysis.
[0003] Currently, there are two reaction pathways for OER (Optical Energy Evolution) in water electrolysis: Adsorbed Oxygen Evolution (AEM) and Lattice Oxygen Oxidation (LOM). AEM is the traditional mechanism for water electrolysis, but it relies heavily on the oxidation of metal active sites, leading to the formation of high-valence substances that eventually dissolve, affecting activity and stability. Furthermore, the formation of OO bonds is restricted, resulting in excessively high overpotentials (typically greater than 300 mV). LOM, on the other hand, bypasses the scaling relationship in OO bond formation during AEM, significantly improving kinetics. Moreover, LOM does not depend on the sustained high valence state of metal sites, mitigating the metal dissolution problem. Therefore, triggering LOM can contribute to improved catalytic activity and stability. However, no method has yet been proposed to definitively trigger LOM; therefore, developing a low-cost method for triggering LOM is crucial for the application of PEMWE (Potential Energy Evolution).
[0004] In recent years, the cost of catalysts has received widespread attention. Cobalt-based oxides have been noted for their unique properties, including a relatively open structure, flexible coordination environment, high theoretical catalytic activity, different metal center coordination structures, and atmospheric stability, making them ideal materials for preparing acidic OERs. However, their catalytic activity in practical applications cannot meet current needs. Therefore, how to trigger the LOM mechanism and modify its intrinsic catalytic activity is a key issue for replacing noble metal catalysts with cobalt-based oxides. Summary of the Invention
[0005] The purpose of this invention is to address the issues of insufficient efficiency and high cost in electrocatalytic oxygen evolution reaction (PEMWE). It provides a method for preparing hexagonal Co-based oxide nanosheets based on oxygen vacancy regulation and its application in acidic oxygen evolution reaction. This method effectively increases the utilization rate of precious metals, reduces costs, triggers the LOM mechanism, improves the catalytic performance of the catalyst, and thus enhances the hydrogen production efficiency of PEMWE.
[0006] The preparation method of Co-based oxide nanosheets based on the oxygen vacancy-regulated reaction mechanism of this invention is carried out according to the following steps:
[0007] 1. The carbon cloth is ultrasonically cleaned to obtain the cleaned carbon cloth;
[0008] II. Using a cobalt salt solution as the electrolyte and cleaned carbon cloth as the working electrode, an electrode was applied at 10~20 mA cm⁻¹. -2 Cobalt hydroxide precursors were obtained by electrodeposition under constant current.
[0009] 3. The cobalt hydroxide precursor obtained in step 2 is immersed in sodium borohydride solution for soaking treatment, and then dried to obtain a precursor with oxygen vacancies.
[0010] IV. Using a precursor with oxygen vacancies as the working electrode, a carbon rod as the counter electrode, and a ruthenium metal salt solution as the electrolyte, an electrode is formed at 10~20 mA cm⁻¹. -2 A ruthenium-loaded cobalt precursor was obtained by electrodeposition under a constant current.
[0011] 5. The ruthenium-supported cobalt precursor was annealed in air at 400-500℃ for 2-4 h to obtain Co-based oxide nanosheets (Ru-Co3O) based on the oxygen vacancy-regulated reaction mechanism. 4-x ).
[0012] The application of the Co-based oxide nanosheets based on the oxygen vacancy-regulated reaction mechanism in this invention is to use the Co-based oxide nanosheets as electrodes in the OER catalytic reaction in acidic solutions.
[0013] The Co-based oxide nanosheets of this invention are applied to the OER catalytic reaction in acidic solutions, which differs from the traditional alkaline water electrolysis catalytic system.
[0014] The Co-based oxide nanosheets (Ru-Co3O) prepared by this invention 4-x As a spinel acidic OER catalyst, the preparation method first synthesizes a Co precursor on conductive carbon cloth by electrodeposition, then treats the oxygen vacancies with sodium borohydride solution, loads the treated precursor with Ru by electrodeposition, and finally anneals at high temperature to obtain Ru-Co3O. 4-x Catalyst. The Ru-Co3O obtained in this invention 4-x The catalyst has a low overpotential, which reduces the amount of noble metal ruthenium used. At the same time, the direct synthesis of the catalyst on a three-dimensional conductive substrate helps to reduce the charge transfer resistance and promote the precipitation of generated bubbles.
[0015] This invention synthesizes Ru-Co3O by a stepwise electrodeposition method. 4-x The material, used to catalyze the oxygen evolution reaction in acidic water electrolysis, offers the following beneficial effects:
[0016] 1. The catalyst of this invention, Ru-Co3O 4-x This invention employs a simple method to increase the number of oxygen vacancies, triggering the LOM (Lead-of-Metal) mechanism and circumventing the limitations of the traditional AEM (Alternating Electrochemical Evolution) mechanism. This lowers the reaction energy barrier and enhances catalytic performance. The method for increasing oxygen vacancies involves soaking the catalyst precursor in a sodium borohydride solution to induce lattice oxygen precipitation. The effect of this sodium borohydride soaking differs from the existing method of increasing active sites through oxygen vacancies in water electrolysis catalysts. This invention triggers the LOM mechanism by increasing the number of oxygen vacancies.
[0017] 2. The catalyst of this invention, Ru-Co3O 4-x The use of the precious metal ruthenium was reduced, the utilization rate of precious metals was improved, and the cost of hydrogen production was reduced.
[0018] 3. The catalyst of this invention, Ru-Co3O 4-x The hexagonal porous nanosheet structure facilitates the exposure of more active sites.
[0019] 4. The catalyst of this invention, Ru-Co3O 4-x Due to the synergistic effect of ruthenium and oxygen vacancies, the catalytic performance of this catalyst is significantly improved compared to Co3O4, exhibiting excellent catalytic activity and stability.
[0020] 5. The present invention Ru-Co3O 4-x The catalyst is composited with a conductive substrate and the bonding is tight, so it can be used directly as an OER electrode without further processing, which is conducive to large-scale industrial applications.
[0021] 6. The catalyst of this invention, Ru-Co3O 4-x This invention has broad application prospects in fields such as hydrogen production through water electrolysis and new energy. The preparation method of this invention is simple, does not require too much equipment, has a low synthesis temperature, and the raw materials are relatively easy to obtain, making it easy to scale up production.
[0022] In summary, the Co-based oxide nanosheets (Ru-Co3O) prepared by this invention... 4-x The catalyst successfully triggered the LOM mechanism through oxygen vacancies and significantly improved the catalytic activity and stability of cobalt tetroxide by loading a small amount of ruthenium. Attached Figure Description
[0023] Figure 1 The image shows the XRD pattern of the Co-based oxide nanosheets prepared in Example 1.
[0024] Figure 2 TEM image of the Co-based oxide nanosheets prepared in Example 1;
[0025] Figure 3 A comparison diagram of the EPR of the catalysts prepared in each example;
[0026] Figure 4 A comparison chart showing the activity test results of the catalysts prepared in each embodiment;
[0027] Figure 5 Impedance comparison diagrams of the catalysts prepared in each example;
[0028] Figure 6 This is a comparison of the pH dependence of the catalysts prepared in each example. Detailed Implementation
[0029] Specific Implementation Method 1: The preparation method of Co-based oxide nanosheets based on the oxygen vacancy-regulated reaction mechanism in this implementation method is carried out according to the following steps:
[0030] 1. The carbon cloth is ultrasonically cleaned to obtain the cleaned carbon cloth;
[0031] II. Using a cobalt salt solution as the electrolyte and cleaned carbon cloth as the working electrode, an electrode was applied at 10~20 mA cm⁻¹. -2 Cobalt hydroxide precursors were obtained by electrodeposition under constant current.
[0032] 3. The cobalt hydroxide precursor obtained in step 2 is immersed in sodium borohydride solution for soaking treatment, and then dried to obtain a precursor with oxygen vacancies.
[0033] IV. Using a precursor with oxygen vacancies as the working electrode, a carbon rod as the counter electrode, and a ruthenium metal salt solution as the electrolyte, an electrode is formed at 10~20 mA cm⁻¹. -2A ruthenium-loaded cobalt precursor was obtained by electrodeposition under a constant current.
[0034] 5. The ruthenium-supported cobalt precursor was annealed in air at 400-500℃ for 2-4 h to obtain Co-based oxide nanosheets (Ru-Co3O) based on the oxygen vacancy-regulated reaction mechanism. 4-x ).
[0035] This implementation method effectively triggers the LOM mechanism through a simple approach, reducing the use of precious metals, Ru-Co3O 4-x It has high catalytic activity.
[0036] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that a carbon rod is used as the counter electrode in step two.
[0037] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the electrodeposition treatment time in step 2 is 20~40 minutes.
[0038] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the concentration of the cobalt salt solution in step two is 0.025~0.075 mol / L.
[0039] Specific Implementation Method 5: This implementation method differs from Specific Implementation Methods 1 to 4 in that the concentration of the sodium borohydride solution in step 3 is 0.2~0.4 mmol / mL.
[0040] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the soaking time in step three is 8 to 20 minutes.
[0041] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the concentration of the ruthenium metal salt solution in step four is 0.002~0.01mol / L RuCl3•9H2O.
[0042] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One through Seven in that step four involves using 10mA cm... -2 Electrodeposition was performed under a constant current for 30-40 minutes.
[0043] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that, in step five, the ruthenium-loaded cobalt precursor is annealed in air at a rate of 5 °C / min to 400-500 °C.
[0044] Example 1: The preparation method of Co-based oxide nanosheets based on the oxygen vacancy-regulated reaction mechanism in this embodiment is carried out according to the following steps:
[0045] 1. The hydrophilic rigid carbon cloth was ultrasonically cleaned sequentially with acetone, ethanol and ultrapure water to obtain the cleaned carbon cloth.
[0046] II. Using a 0.05 mol / L Co(NO3)2•6H2O solution as the electrolyte, cleaned carbon cloth as the cathode, and a carbon rod as the anode, an electrode was applied at 10 mA / cm². -2 Cobalt hydroxide precursor was obtained by electrodeposition under constant current for 30 min.
[0047] 3. Immerse the cobalt hydroxide precursor obtained in step 2 in a 0.2 mol / L sodium borohydride solution for 10 min, and then dry to obtain a precursor with oxygen vacancies.
[0048] IV. Using a precursor with oxygen vacancies as the cathode, a carbon rod as the anode, and a 0.005 mol / L RuCl3•9H2O solution as the electrolyte, at a concentration of 10 mA cm⁻¹. -2 A ruthenium-loaded cobalt precursor was obtained by electrodeposition under a constant current for 30 min.
[0049] 5. The ruthenium-supported cobalt precursor was annealed in air at a temperature of 400℃ at a rate of 5℃ / min for 3 hours, and then naturally cooled to room temperature to obtain Co-based oxide nanosheets (Ru-Co3O) based on the oxygen vacancy-regulated reaction mechanism. 4-x ).
[0050] In this embodiment, the Co-based oxide nanosheet OER catalyst was denoted as Ru-Co3O. 4-x .
[0051] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that step 3 is not performed on the cobalt precursor. Other steps and parameters are the same as in Example 1.
[0052] The OER catalyst obtained by comparison with Example 1 is denoted as Ru-Co3O4.
[0053] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that step four is not performed on the cobalt precursor with oxygen vacancies. Other steps and parameters are the same as in Example 1.
[0054] The OER catalyst obtained in Comparative Example 2 is denoted as Co3O 4-x .
[0055] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that steps 3 and 4 are not performed on the cobalt precursor with oxygen vacancies. Other steps and parameters are the same as in Example 1.
[0056] The OER catalyst obtained in Comparative Example 3 is denoted as Co3O4.
[0057] Co3O 4-x Testing of the acidic OER performance of Ru catalyst:
[0058] 1. Electrode preparation: The Ru-Co3O obtained in Example 1 was used... 4-x The electrodes were cut to 1×0.5cm. 2 The rectangular shape is fixed with a platinum electrode clamp and used as the working electrode.
[0059] 2. Solution preparation: To test the OER performance of the sample prepared in Example 1, 0.5 mol / L H2SO4 was used as the electrolyte.
[0060] 3. Testing: Figure 1 The catalyst Ru-Co3O prepared in Example 1 4-x The XRD pattern of the catalyst shows that the peak positions correspond to those of the standard card PDF#43-1003 for Co3O4. Figure 2 The catalyst Ru-Co3O prepared in Example 1 4-x The TEM image shows that the catalyst has a morphology of hexagonal nanosheets with a side length of approximately 200 nm. Figure 3 The catalyst Ru-Co3O prepared in Example 1 4-x The EPR graph shows Ru-Co3O 4-x It has the most oxygen vacancies. A three-electrode system was used, with the working electrode being Ru-Co3O prepared in Example 1. 4-x The electrodes were a graphite rod as the counter electrode and an Ag / AgCl electrode as the reference electrode. First, all three electrodes were immersed in 0.5 mol / L H₂SO₄ and Ru-Co₃O₄ solution. 4-x The electrode's immersion area in the electrolyte is 0.5 × 0.5 cm. 2 Cyclic voltammetry was performed using an electrochemical workstation to activate the sample, with a scan range of 0.9 V–1.8 V vs. Ag / AgCl and a scan rate of 100 mV / s. The linear voltammetry (LSV) curve of the sample was then measured, with a scan range of 0.9 V–1.8 V vs. Ag / AgCl and a scan rate of 5 mV / s. The results are as follows: Figure 4 As shown, when the current density reaches 10 mA cm⁻¹ -2 The overpotential at that time was 198 mV. Furthermore, LSV tests were performed on Control Examples 1, 2, and 3 under the same conditions, and their overpotentials were 220 mV, 290 mV, and 380 mV, respectively. Then, the electrochemical impedance spectroscopy (EIS) of the samples was measured at a voltage of 1.35 V vs. Ag / AgCl, with a frequency range of 0.1 Hz to 10 Hz. 6 Hz, the result is as follows Figure 5As shown, EIS tests were performed on Examples 2, 3, and 4 under the same conditions. It can be seen that Example 1 exhibits the lowest charge transfer resistance and higher electrochemical catalytic activity. Ru-Co3O 4-x The electrode exhibits better OER catalytic activity. Figure 6 The pH dependence graphs for Example 1 and Comparative Examples 2, 3, and 4 are a method for examining the reaction mechanism of catalysts. Specifically, as pH changes, the catalytic performance changes accordingly; the stronger the pH dependence of the performance, the stronger the LOM mechanism. Figure 6 As shown, Example 1 exhibits a clear pH dependence, while the control example does not show a significant pH dependence. This sufficiently demonstrates the effectiveness of Ru-Co3O in Example 1. 4-x The catalyst triggered the LOM mechanism, while the pH dependence of other samples was not obvious, which indicates that their reaction mechanism does not follow the LOM mechanism.
[0061] 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, improvements, etc., 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 preparing Co-based oxide nanosheets based on an oxygen vacancy-regulated reaction mechanism, characterized in that... The preparation method of Co-based oxide nanosheets based on the oxygen vacancy-regulated reaction mechanism is carried out according to the following steps:
1. The carbon cloth is ultrasonically cleaned to obtain the cleaned carbon cloth; II. Using a cobalt salt solution as the electrolyte and cleaned carbon cloth as the working electrode, an electrode was applied at 10~20 mA cm⁻¹. -2 The cobalt hydroxide precursor was obtained by electrodeposition under a constant current, wherein the cobalt salt solution was a Co(NO3)2•6H2O solution.
3. Immerse the cobalt hydroxide precursor obtained in step 2 in a sodium borohydride solution with a concentration of 0.2~0.4 mmol / mL for 8~20 min, and then dry to obtain a precursor with oxygen vacancies. IV. Using a precursor with oxygen vacancies as the working electrode, a carbon rod as the counter electrode, and a ruthenium metal salt solution as the electrolyte, an electrode is formed at 10~20 mA cm⁻¹. -2 The ruthenium-loaded cobalt precursor was obtained by electrodeposition under constant current, wherein the ruthenium metal salt solution was a 0.002~0.01 mol / L RuCl3•9H2O solution; 5. The ruthenium-supported cobalt precursor was annealed in air at 400℃ for 2-4 h to obtain Co-based oxide nanosheets Ru-Co3O based on the oxygen vacancy-regulated reaction mechanism. 4-x .
2. The method for preparing Co-based oxide nanosheets based on the oxygen vacancy-regulated reaction mechanism according to claim 1, characterized in that... In step two, a carbon rod is used as the counter electrode.
3. The method for preparing Co-based oxide nanosheets based on the oxygen vacancy-regulated reaction mechanism according to claim 1, characterized in that... The electrodeposition process in step two takes 20 to 40 minutes.
4. The method for preparing Co-based oxide nanosheets based on the oxygen vacancy-regulated reaction mechanism according to claim 1, characterized in that... In step two, the concentration of the cobalt salt solution is 0.025~0.075 mol / L.
5. The method for preparing Co-based oxide nanosheets based on the oxygen vacancy-regulated reaction mechanism according to claim 1, characterized in that... In step four, at 10mA cm -2 Electrodeposition was performed under a constant current for 30-40 minutes.
6. The method for preparing Co-based oxide nanosheets based on the oxygen vacancy-regulated reaction mechanism according to claim 1, characterized in that... In step five, the ruthenium-loaded cobalt precursor is annealed in air at a rate of 5 °C / min to 400 °C.
7. The application of the Co-based oxide nanosheets prepared by the method described in claim 1, characterized in that... The Co-based oxide nanosheets were used as electrodes in the OER catalytic reaction in acidic solutions.