A method for preparing a highly efficient and stable electrochemical oxygen evolution catalyst

Abstract

This invention discloses a method for preparing a highly efficient and stable electrochemical oxygen evolution catalyst. The preparation steps are as follows: First, ruthenium oxide is prepared by precipitation-calcination method. Then, ruthenium oxide powder is placed in a metal salt solution, the solvent is evaporated and dried to obtain a metal salt-ruthenium oxide precursor. The metal salt-ruthenium oxide precursor is calcined under an inert gas, washed and dried to obtain metal salt-ruthenium oxide powder. Finally, the metal salt-ruthenium oxide powder is calcined and cooled to room temperature to obtain a highly efficient and stable electrochemical oxygen evolution catalyst. The catalyst preparation process of this invention is simple and easy to scale up, effectively reducing the cost of ruthenium-based electrocatalysts. It exhibits excellent electrocatalytic oxygen evolution activity and stability in acidic systems.

Description

Technical Field

[0001] This invention relates to a method for preparing a highly efficient and stable electrochemical oxygen evolution catalyst, belonging to the fields of materials preparation and electrocatalysis technology. Background Technology

[0002] Electrocatalytic reactions driven by sustainable electricity offer an effective way to address the increasingly serious energy and environmental problems we face today. The oxygen evolution reaction (OER) is an important electrochemical half-reaction that provides abundant protons and electrons for numerous electrochemical applications, such as water electrolysis for hydrogen production, electrochemical carbon dioxide reduction, and electrochemical nitrate reduction for ammonia production. However, as an electrochemical reaction involving multiple electron / proton transfers, the OER exhibits sluggish reaction kinetics and requires high overpotentials. In this context, the use of efficient catalysts is beneficial for accelerating the OER process and reducing the overpotential, thereby reducing the overall energy consumption of the electrocatalytic reaction system and accelerating the application of electrocatalysis. Typically, the electrocatalytic OER process takes place under corrosive (acidic or alkaline) electrolytes and oxidation potential conditions, posing a significant technical challenge to the development of efficient and stable electrochemical oxygen evolution catalysts. Furthermore, due to the poor stability and low activity of non-noble transition metals under acidic oxygen evolution conditions, the development of efficient electrochemical oxygen evolution catalysts based on noble metals (ruthenium and iridium) has become a core technology and research hotspot in this field.

[0003] Iridium-based catalysts are highly efficient and stable electrocatalysts for acidic oxygen evolution, and related preparation techniques have been reported. For example, patent CN 115747857 A discloses a method for preparing an iridium oxide@ruthenium oxide composite catalyst suitable for the electrochemical oxygen evolution of acidic water, obtaining a core-shell nanocomposite catalyst with iridium oxide coated with ruthenium oxide. This catalyst exhibits uniform phase distribution, more electrochemical active sites, good catalytic activity, and long chemical durability. However, iridium metal is very rare and expensive, limiting the widespread application of iridium-based oxygen evolution electrocatalysts. Since the price of ruthenium per unit mass is approximately 10% of that of iridium, the design and development of ruthenium-based oxygen evolution catalysts has attracted considerable attention. Previous reports have also confirmed the high OER activity of ruthenium-based catalysts, but their performance stability is still difficult to meet current requirements due to the tendency of ruthenium-based catalysts to form soluble ruthenium species during use. Developing a ruthenium-based oxygen evolution electrocatalyst with high activity, stable performance, and ease of large-scale synthesis remains an important approach to promoting the widespread application of this type of catalyst. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a highly efficient and stable ruthenium-based electrocatalyst for use in the electrochemical oxygen evolution reaction.

[0005] To achieve its objectives, the present invention employs the following technical solution:

[0006] A method for preparing a highly efficient and stable electrochemical oxygen evolution catalyst is carried out according to the following steps:

[0007] (1) Dissolve ruthenium salt in a mixture of pure water and ethanol, adjust the pH of the ruthenium salt solution to neutral by injecting potassium hydroxide solution, stir the reaction for 0.5-48 hours, collect the precipitate, wash it with pure water and ethanol in sequence, dry it and grind it to obtain the ruthenium precursor;

[0008] (2) The ruthenium precursor is calcined in air at 400-700°C for 2-48 hours and then cooled to room temperature to obtain ruthenium oxide powder;

[0009] (3) The ruthenium oxide powder is placed in a metal salt solution, ultrasonically treated for 10-60 minutes, the solvent is evaporated and dried to obtain the metal salt-ruthenium oxide precursor;

[0010] (4) The metal salt-ruthenium oxide precursor was calcined in an inert gas at 200-400°C for 2-10 hours, cooled to room temperature, and the resulting product was washed with pure water and ethanol in sequence and dried to obtain metal salt-ruthenium oxide powder.

[0011] (5) The metal salt-ruthenium oxide powder is calcined in air at 400-600°C for 2-10 hours and then cooled to room temperature to obtain the efficient and stable electrochemical oxygen evolution catalyst.

[0012] Preferably, in step (1), the volume ratio of pure water to ethanol in the mixture is 1:0.1 to 10.

[0013] Preferably, in step (1), the concentration of the potassium hydroxide solution is 0.01-10 mol / L.

[0014] Preferably, in step (3), the metal salt is a salt of at least one metal selected from iron, cobalt, nickel, manganese, molybdenum and rhenium, and the solvent used to dissolve the metal salt is at least one selected from water, ethanol, methanol and acetone.

[0015] Preferably, in step (3), the concentration of the metal salt solution is 0.5-10 mmol / 200 mL, and the ratio of ruthenium oxide powder to metal salt solution is 1 g:200 mL.

[0016] Preferably, in step (4), the inert gas is at least one of nitrogen, argon and helium.

[0017] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0018] 1. The catalyst preparation method provided by the present invention has the advantages of simple process, good repeatability, easy control and easy scale-up preparation, and can realize industrial application.

[0019] 2. The catalyst provided by this invention can be applied to the oxygen evolution reaction under acidic conditions and has excellent electrochemical activity and reliable stability.

[0020] 3. The catalyst provided by this invention reduces the amount of ruthenium metal used, effectively reducing the actual cost of ruthenium-based oxygen evolution electrocatalysts, and has broad application prospects. Attached Figure Description

[0021] Figure 1 The image shows a scanning electron microscope (SEM) image of the ruthenium-based oxygen evolution catalyst prepared in Example 1.

[0022] Figure 2 This is a linear sweep voltammetry (LSV) curve from Example 1;

[0023] Figure 3 This is a current-time (it) curve of the constant voltage test in Example 1. Detailed Implementation

[0024] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following content is merely illustrative and explanatory of the concept of the present invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the inventive concept or exceed the scope defined by the claims, all of which should fall within the protection scope of the present invention.

[0025] Example 1

[0026] (1) Dissolve 0.75g of ruthenium chloride in a mixture of 140mL of pure water and ethanol (volume ratio: 1:1). Adjust the pH of the ruthenium chloride solution to neutral by injecting 1mol / L potassium hydroxide solution. Stir the reaction for 1 hour, collect the precipitate by centrifugation, wash it three times with pure water and ethanol in sequence, dry it in an oven at 80℃, and grind it to obtain the black ruthenium precursor.

[0027] (2) The ruthenium precursor obtained in step (1) is placed in a muffle furnace and calcined at 500°C for 5 hours in an air atmosphere. After cooling to room temperature, ruthenium oxide powder is obtained.

[0028] (3) The ruthenium oxide powder (0.1 g) obtained in step (2) is placed in 20 mL of ethanol solution containing 0.1 mmol of manganese dichloride, sonicated for 15 minutes, the solvent is evaporated and dried to obtain manganese chloride-ruthenium oxide precursor.

[0029] (4) The manganese chloride-ruthenium oxide precursor obtained in step (3) was calcined in a nitrogen muffle furnace at 300°C for 5 hours, cooled to room temperature, and the resulting product was washed three times with pure water and ethanol, and dried in an oven at 80°C to obtain manganese chloride-ruthenium oxide powder.

[0030] (5) The manganese chloride-ruthenium oxide powder obtained in step (4) is calcined in a muffle furnace at 550°C for 5 hours in an air atmosphere and then cooled to room temperature to obtain a highly efficient and stable electrochemical oxygen evolution catalyst.

[0031] Figure 1 The image shows a SEM image of the catalyst prepared in this embodiment. The catalyst is a nanoparticle with a minimum nanoparticle diameter of approximately 50 nm.

[0032] Eight mg of the catalyst prepared in this example and 2 mg of carbon black were ultrasonically dispersed in a mixed solution of anhydrous ethanol (760 μL) and 5 wt% Nafion (40 μL) to obtain a catalyst dispersion. 10 μL of the catalyst dispersion was drop-coated onto a titanium mesh (0.5 cm * 0.5 cm) and air-dried to serve as the working electrode. Under normal temperature and pressure, the electrochemical oxygen evolution performance of the catalyst was tested in a standard three-electrode system (counter electrode: graphite rod electrode; reference electrode: silver / silver chloride electrode) using 0.5 mol / L sulfuric acid solution as the electrolyte. Figure 2 The obtained LSV plots show that the performance of the prepared catalyst is superior to that of industrial ruthenium dioxide catalysts, achieving a 10 mA cm⁻¹ at 1.54 V (relative to a standard reversible hydrogen electrode). -2 The oxygen evolution current density. Figure 3 The obtained it diagram shows that the catalyst can provide a stable oxygen evolution current output under constant voltage, indicating that the catalyst has excellent electrochemical stability.

[0033] Example 2

[0034] (1) Dissolve 0.75 g of ruthenium chloride in a mixture of 150 mL of pure water and ethanol (volume ratio: 1:1). Adjust the pH of the ruthenium chloride solution to neutral by injecting 0.5 mol / L potassium hydroxide solution. Stir the reaction for 1.5 hours, collect the precipitate by centrifugation, wash it three times with pure water and ethanol in sequence, dry it in an oven at 75 °C, and grind it to obtain the black ruthenium precursor.

[0035] (2) The ruthenium precursor obtained in step (1) is placed in a muffle furnace and calcined at 550°C for 5 hours in an air atmosphere. After cooling to room temperature, ruthenium oxide powder is obtained.

[0036] (3) The ruthenium oxide powder (0.1g) obtained in step (2) is placed in 20mL of ethanol solution containing 0.4mmol manganese dichloride, sonicated for 30 minutes, the solvent is evaporated and dried to obtain manganese chloride-ruthenium oxide precursor.

[0037] (4) The manganese chloride-ruthenium oxide precursor obtained in step (3) was calcined in a nitrogen muffle furnace at 350°C for 5.5 hours, cooled to room temperature, and the resulting product was washed three times with pure water and ethanol, and dried in an oven at 75°C to obtain manganese chloride-ruthenium oxide powder.

[0038] (5) The manganese chloride-ruthenium oxide powder obtained in step (4) is calcined in a muffle furnace at 600°C for 5 hours in an air atmosphere and then cooled to room temperature to obtain a highly efficient and stable electrochemical oxygen evolution catalyst.

[0039] Example 3

[0040] (1) Dissolve 1.5g of ruthenium chloride in a mixture of 140mL of pure water and ethanol (volume ratio: 1:1). Adjust the pH of the ruthenium chloride solution to neutral by injecting 1mol / L potassium hydroxide solution. Stir the reaction for 2 hours, collect the precipitate by centrifugation, wash it three times with pure water and ethanol in sequence, dry it in an oven at 80℃, and grind it to obtain the black ruthenium precursor.

[0041] (2) The ruthenium precursor obtained in step (1) is placed in a muffle furnace and calcined at 600°C for 6 hours in an air atmosphere. After cooling to room temperature, ruthenium oxide powder is obtained.

[0042] (3) The ruthenium oxide powder (0.1 g) obtained in step (2) is placed in 20 mL of ethanol solution containing 0.1 mmol nickel chloride, sonicated for 15 minutes, the solvent is evaporated and dried to obtain nickel chloride-ruthenium oxide precursor.

[0043] (4) The nickel chloride-ruthenium oxide precursor obtained in step (3) was calcined in a nitrogen muffle furnace at 300°C for 5 hours, cooled to room temperature, and the resulting product was washed three times with pure water and ethanol, and dried in an oven at 80°C to obtain nickel chloride-ruthenium oxide powder.

[0044] (5) The nickel chloride-ruthenium oxide powder obtained in step (4) is calcined in a muffle furnace at 500°C for 5 hours in an air atmosphere and then cooled to room temperature to obtain a highly efficient and stable electrochemical oxygen evolution catalyst.

[0045] Example 4

[0046] (1) Dissolve 0.75 g of ruthenium chloride in a mixture of 140 mL of pure water and ethanol (volume ratio: 1:1). Adjust the pH of the solution to neutral by injecting 1 mol / L potassium hydroxide solution. Stir the reaction for 1 hour, collect the precipitate by centrifugation, wash it three times with pure water and ethanol in sequence, dry it in an oven at 80 °C, and grind it to obtain the black ruthenium precursor.

[0047] (2) The ruthenium precursor obtained in step (1) is placed in a muffle furnace and calcined at 500°C for 5 hours in an air atmosphere. After cooling to room temperature, ruthenium oxide powder is obtained.

[0048] (3) The ruthenium oxide powder (0.1 g) obtained in step (2) is placed in 20 mL of ethanol solution containing 0.1 mmol molybdenum pentachloride, sonicated for 15 minutes, the solvent is evaporated and dried to obtain the molybdenum chloride-ruthenium oxide precursor.

[0049] (4) The molybdenum chloride-ruthenium oxide precursor obtained in step (3) was calcined in a nitrogen muffle furnace at 300°C for 5 hours, cooled to room temperature, and the resulting product was washed three times with pure water and ethanol, and dried in an oven at 80°C to obtain molybdenum chloride-ruthenium oxide powder.

[0050] (5) The molybdenum chloride-ruthenium oxide powder obtained in step (4) is calcined in a muffle furnace at 550°C for 5 hours in an air atmosphere and then cooled to room temperature to obtain a highly efficient and stable electrochemical oxygen evolution catalyst.

[0051] The above are merely exemplary embodiments of the present invention and are 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 preparing a highly efficient and stable electrochemical oxygen evolution catalyst, characterized in that, The preparation method comprises the following steps: (1) dissolving a ruthenium salt in a mixture of pure water and ethanol, adjusting the pH of the ruthenium salt solution to neutral by injecting a potassium hydroxide solution, stirring the reaction for 0.5-48 hours, collecting the precipitate, washing with pure water and ethanol in sequence, drying and grinding to obtain a ruthenium precursor; (2) calcining the ruthenium precursor at 400-700 ℃ for 2-48 hours under an air atmosphere, cooling to room temperature to obtain a ruthenium oxide powder; (3) placing the ruthenium oxide powder into a metal salt solution, ultrasonic treatment for 10-60 minutes, evaporating the solvent and drying to obtain a metal salt-ruthenium oxide precursor; the metal salt is a manganese salt, the concentration of the metal salt solution is 0.5-10 mmol / 200 mL, and the use amount ratio of the ruthenium oxide powder to the metal salt solution is 1 g:200 mL; (4) calcining the metal salt-ruthenium oxide precursor at 200-400 ℃ for 2-10 hours in an inert gas, cooling to room temperature, washing the obtained product with pure water and ethanol in sequence, drying to obtain a metal salt-ruthenium oxide powder; (5) calcining the metal salt-ruthenium oxide powder at 400-600 ℃ for 2-10 hours under an air atmosphere, cooling to room temperature to obtain the high-efficiency and stable electrochemical oxygen evolution catalyst.

2. The method of claim 1, wherein: In step (1), the volume ratio of pure water to ethanol in the mixture is 1:0.1-10.

3. The method of claim 1, wherein: In step (1), the concentration of the potassium hydroxide solution is 0.01-10 mol / L.

4. The method of claim 1, wherein: In step (3), the solvent for dissolving the metal salt is at least one of water, ethanol, methanol and acetone.

5. The method of claim 1, wherein: In step (4), the inert gas is at least one of nitrogen, argon and helium.

6. An electrochemical oxygen evolution catalyst prepared by the preparation method in any one of claims 1-5.

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