A ruthenium oxide catalyst for oxygen evolution with a surface presenting a conical protrusion structure, and a preparation method and application thereof
Ruthenium oxide catalysts with conical protrusions on the surface were prepared by atmospheric pressure heating-programmed temperature calcination method, which solved the problems of easy solubility of RuO2 in acidic media and the decline in catalytic performance, and achieved efficient and stable electrocatalytic performance, suitable for hydrogen production by water electrolysis.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
- Filing Date
- 2024-12-03
- Publication Date
- 2026-06-05
AI Technical Summary
Existing Ru-based catalysts are complex to prepare, have low Ru atom conversion and yield, and RuO2 is easily soluble in acidic media and its surface structure is easily modified, resulting in a decline in catalytic performance. Furthermore, commercially available catalysts have insufficient activity and stability.
Ruthenium oxide catalysts with conical protrusions on the surface were prepared by atmospheric pressure heating-programmed temperature calcination method. The catalysts were prepared by mixing RuCl3 with urea solution, filtering, washing, drying, and then calcining in a muffle furnace with programmed temperature control to form nano-tetrahedral conical structures.
The preparation process is simple and environmentally friendly. The catalyst exhibits high oxygen evolution activity and stability in acidic media, which significantly improves the electrocatalytic performance of RuO2 and is suitable for hydrogen production by water electrolysis.
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Figure CN122147393A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of oxygen evolution catalyst technology, specifically relating to a ruthenium oxide crystal oxygen evolution catalyst with a cone-shaped protrusion structure on its surface, its preparation method, and its application. Background Technology
[0002] To address global warming, energy shortages, and rising prices, the shift from traditional fossil fuels to renewable energy and the decarbonization of the energy system are both necessary and urgent. Hydrogen, with its high energy density, zero carbon emissions, and ease of transportation and storage, has attracted considerable attention among new energy sources. Hydrogen energy is a crucial breakthrough for achieving carbon neutrality, not only replacing the direct consumption of fossil fuels and promoting cleaner end-use energy, but also having wide applications in transportation, steelmaking, chemicals, power generation, and heating. It is also an important carrier for energy storage, distribution, and utilization. In recent years, the rapid development of renewable energy power generation has created favorable conditions for the development of hydrogen production through water electrolysis.
[0003] Studies have shown that the high proton conductivity, gas tightness, and low film thickness (~20-300 μm) of solid polymer electrolyte membranes (Nafion) give PEM electrolyzers advantages such as high hydrogen purity, high current density, compact design, and fast system response. However, on the one hand, the anodic oxygen evolution reaction (OER) in water electrolysis is a four-electron transfer process, and its high energy barrier increases energy consumption and limits the overall energy efficiency of hydrogen production from water electrolysis. On the other hand, anodic catalyst materials in PEM electrolyzers face the dual challenges of corrosion from strong acid environments and anodic oxidation. Therefore, developing anodic oxygen evolution catalysts with excellent performance and long-term durability for the anodic oxygen evolution reaction in acidic media is necessary to promote the development of efficient water electrolysis for hydrogen production.
[0004] Furthermore, studies have shown that RuO2 electrocatalysts exhibit excellent activity and high stability under acidic conditions, and their cost is only about one-tenth that of commercial Ir materials, making RuO2 one of the most promising candidates for OER catalysts to replace expensive Ir-based catalysts. Meanwhile, the surface morphology of the catalyst has a significant impact on catalytic performance. Conical surfaces, especially at their tips, contain more high-energy atoms. These atoms are not completely surrounded and form weaker bonds with surrounding atoms, thus their reactivity is generally higher. Moreover, atoms at the tips are more likely to accept or release electrons, which makes the conical ruthenium oxide surface exhibit stronger catalytic activity in redox reactions.
[0005] However, current Ru-based material preparation methods suffer from complex steps, low Ru atom conversion rates, and low yields. Furthermore, RuO2 is prone to dissolution and / or surface structure transformation, leading to a sharp decline in catalytic performance. Therefore, developing simple, reproducible, large-scale synthesis processes with high Ru atom utilization to prepare RuO2 anodic oxygen evolution catalysts with excellent electrocatalytic oxygen evolution performance and good stability is of great significance. Summary of the Invention
[0006] To address the aforementioned technical problems, the present invention aims to provide a ruthenium oxide oxygen evolution catalyst with a cone-shaped protrusion structure on its surface, as well as its preparation method and application, in order to solve the problems of poor electrocatalytic activity, high price, poor stability, and complex preparation process of existing oxygen evolution catalysts.
[0007] In a first aspect, the present invention provides a method for preparing a ruthenium oxide oxygen evolution catalyst with a surface exhibiting a cone-shaped protrusion structure, the preparation method comprising the following steps: (1) Mix RuCl3 solution with urea solution and heat under normal pressure. After filtration, washing and drying, ruthenium precursor is obtained. (2) The ruthenium precursor is subjected to programmed heating and calcination, and after cooling, the ruthenium oxide oxygen evolution catalyst with a cone-shaped protrusion structure on the surface is obtained.
[0008] Preferably, in step (1), the concentration of the RuCl3 solution is 20-50 g / L, the concentration of the urea solution is 10-40 g / L, and the volume ratio of the RuCl3 solution to the urea solution is 5-10:100-300.
[0009] Preferably, in step (1), the atmospheric pressure heating is carried out in an oil bath; the heating temperature is 40-75°C, preferably 60-75°C, and the heating time is 2-5 hours, preferably 3-4 hours.
[0010] Preferably, in step (1), the number of times of filtration and washing is 5 to 15; the drying method is vacuum drying, the drying temperature is 50 to 100°C, and the drying time is 10 to 20 hours.
[0011] Preferably, step (2) further includes a process of pre-treating the ruthenium precursor before calcination; wherein the pre-treatment process includes organic solvent cleaning, deionized water cleaning, drying and grinding.
[0012] Preferably, in step (2), the programmed temperature rise calcination is carried out in a muffle furnace, and the calcination atmosphere is air or argon atmosphere; the programmed temperature rise calcination temperature is 250-500℃, the calcination time is 1-5h, and the heating rate is 1-5℃ / min; preferably, the calcination temperature is 250-400℃, the calcination time is 2.5-3.5h, and the heating rate is 2.5-3.5℃ / min.
[0013] Secondly, the present invention provides a ruthenium oxide oxygen evolution catalyst with a conical protrusion structure on its surface, obtained according to the above preparation method. The surface of the ruthenium oxide oxygen evolution catalyst has a raised nano-tetrahedral pyramidal structure with a specific surface area of 15-30 m². 2 / g.
[0014] Preferably, the ruthenium oxide oxygen evolution catalyst with a cone-shaped protrusion structure on its surface has a crystallization degree of 80-98% and a grain size of 5-30 nm.
[0015] Preferably, the ruthenium oxide oxygen evolution catalyst with a cone-shaped protrusion structure on its surface can achieve an overpotential of 10 mA cm⁻¹ at an overpotential of 190-230 mV. -2 The current density can reach 100 mA cm⁻¹ at an overpotential of 250-300 mV. -2 The current density.
[0016] Thirdly, the present invention provides an application of the above-mentioned ruthenium oxide oxygen evolution catalyst with a cone-shaped protrusion structure on its surface in the electrocatalytic oxygen evolution process.
[0017] Beneficial effects (1) The present invention uses atmospheric pressure heating-programmed temperature rise calcination method to prepare and obtain uniform ruthenium oxide oxygen evolution catalyst, and has the advantages of simple process, easy operation, environmental friendliness, strong repeatability and large output. (2) The RuO2 electrocatalyst prepared in this invention has a large specific surface area and its active sites are directly exposed on the surface, which improves the mass transport. It exhibits more efficient oxygen evolution activity than commercial RuO2 and IrO2 in acidic media and can maintain stable performance under long-term current. It has broad application prospects in the field of electrocatalysis. Attached Figure Description
[0018] Figure 1 The X-ray diffraction pattern of ruthenium oxide (RuO2) with a cone-shaped protrusion structure on the surface obtained in Example 1 of the present invention; Figure 2 This is a scanning electron microscope image of the ruthenium oxide (RuO2) catalyst with a cone-shaped protrusion structure on its surface prepared in Example 1 of the present invention; Figure 3This is a transmission electron microscope (TEM) image of the ruthenium oxide (RuO2) catalyst with a cone-shaped protrusion structure on its surface prepared in Example 1 of the present invention. Figure 4 This is a scanning electron microscope image of ruthenium oxide (DI-RuO2) prepared in Comparative Example 1 of the present invention; Figure 5 This is a transmission electron microscope image of ruthenium oxide (DI-RuO2) prepared in Comparative Example 1 of the present invention; Figure 6 This is a scanning electron microscope image of ruthenium oxide prepared in Comparative Example 2 of the present invention; Figure 7 The oxygen evolution reaction anodic polarization curves are shown for the ruthenium oxide (RuO2) catalyst with a cone-shaped protrusion structure prepared in Example 1 of the present invention, the ruthenium oxide (DI-RuO2) prepared in Comparative Example 1, and the commercial RuO2 catalyst (Com-RuO2) and the commercial IrO2 catalyst (Com-IrO2). Figure 8 This diagram illustrates the oxygen evolution reaction stability of the ruthenium oxide (RuO2) catalyst with a cone-shaped protrusion structure prepared in Example 1 of the present invention, as well as the commercial RuO2 catalyst (Com-RuO2) and the commercial IrO2 catalyst (Com-IrO2). Detailed Implementation
[0019] The present invention will be further illustrated by the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the present invention.
[0020] The following is an exemplary description of a method for preparing a ruthenium oxide oxygen evolution catalyst with a surface exhibiting a cone-shaped protrusion structure, provided by the present invention. The preparation method may include the following steps: (1) Mix RuCl3 solution with urea solution and heat under normal pressure. After filtration, washing and drying, ruthenium precursor is obtained. (2) The ruthenium precursor is subjected to programmed heating and calcination, and after cooling, the ruthenium oxide oxygen evolution catalyst with a cone-shaped protrusion structure on the surface is obtained.
[0021] In some embodiments, in step (1), the solvents in both the RuCl3 solution and the urea solution can be ethanol or deionized water; the concentration of the RuCl3 solution can be 20-50 g / L, preferably 40-45 g / L; the concentration of the urea solution can be 10-40 g / L, preferably 15-25 g / L; and the volume ratio of the RuCl3 solution to the urea solution can be 5-10:100-300, preferably 5-10:180-220.
[0022] The concentration and dosage ratio of RuCl3 and urea in the solution affect the dispersion, particle size, and yield of the catalyst precursor material, ultimately influencing the electrochemical active surface area and oxygen evolution performance of the catalyst. Urea acts as both a reducing agent and a precipitant. When the dosage of urea is low, the reduction of ruthenium is incomplete, resulting in some ruthenium chloride remaining unreduced and precipitating as ruthenium species. This reduces the yield of the catalyst product and introduces more ruthenium chloride impurities, which have lower catalytic activity, affecting the efficiency of the catalytic reaction. Excessive urea dosage leads to overly rapid ruthenium reduction, causing the formation of larger particles or unevenly distributed aggregates. This reduces the specific surface area of the catalyst, decreases the number of active sites for the catalytic reaction, and thus reduces catalytic performance.
[0023] In some embodiments, in step (1), the atmospheric pressure heating can be carried out in an oil bath; the heating temperature can be 40-75°C, preferably 60-75°C, and the heating time can be 2-5 hours, preferably 3-4 hours.
[0024] Oil has a high specific heat capacity, low volatility at normal pressure, and good thermal conductivity. Therefore, an oil bath can stably transfer heat for a relatively long period, ensuring uniform temperature distribution during the heating process. If the temperature is too high, the solvent begins to evaporate, leading to uneven local temperatures in the reaction liquid, causing local reactions to be too fast or too slow, thus affecting the uniformity of the reaction. If the temperature is too low, it will affect the reaction rate and may lead to incomplete reduction, incomplete or uneven precipitation, affecting the quality of the catalyst. Furthermore, excessively long heating times can cause ruthenium particles to aggregate or crystallize during heat treatment, resulting in excessively large final catalyst particles and reduced catalytic activity. Insufficient heating times can easily lead to incomplete reduction and uneven precipitation, affecting the yield and performance of the catalyst.
[0025] In some embodiments, in step (1), the number of times of filtration and washing can be 5 to 15; the drying method can be vacuum drying, the drying temperature can be 50 to 100°C, and the drying time can be 10 to 20 hours.
[0026] In some embodiments, step (2) further includes a pretreatment process for the ruthenium precursor before calcination; wherein the pretreatment process may include organic solvent cleaning, deionized water cleaning, drying and grinding.
[0027] In some embodiments, in step (2), the programmed temperature rise calcination can be carried out in a muffle furnace, and the calcination atmosphere can be air or argon atmosphere; the programmed temperature rise calcination temperature can be 250-500℃, the calcination time can be 1-5h, and the heating rate can be 1-5℃ / min; preferably, the calcination temperature is 250-400℃, the calcination time is 2.5-3.5h, and the heating rate is 2.5-3.5℃ / min.
[0028] Programmed calcination of the ruthenium precursor can remove volatile impurities while obtaining a specific crystal form, crystal size, pore structure, and specific surface area. Controlling the calcination temperature, holding time, and heating rate within appropriate parameter ranges ensures that the prepared catalyst material has a suitable specific surface area, degree of crystallization, and grain size; otherwise, defects such as excessively large catalyst particles will directly affect its oxygen evolution performance.
[0029] The preparation method provided by the present invention has the advantages of simple and efficient process, large output, environmental friendliness and strong reproducibility. At the same time, the oxygen evolution catalyst obtained by the preparation method shows high oxygen evolution activity and cycle stability under acidic conditions.
[0030] The ruthenium oxide oxygen evolution catalyst (RuO2) with a cone-shaped protrusion structure obtained by the preparation method provided by this invention has a nano-tetrahedral pyramidal structure with a convex surface and a specific surface area of 15-30 m². 2 / g; crystallization degree is 80%-98%, and grain size is 5-30nm.
[0031] The ruthenium oxide crystals prepared by this invention exhibit well-controlled surface morphology, thereby regulating the electronic structure of the ruthenium active sites and resulting in excellent electrocatalytic oxygen evolution performance. In some embodiments, the ruthenium oxide oxygen evolution catalyst with a cone-shaped protrusion structure provided by this invention can achieve an overpotential of 10 mA cm⁻¹ at an overpotential of 190-230 mV. -2 The current density can reach 100 mA / cm² at an overpotential of 250-300 mV. -2 The current density.
[0032] It should be noted that the conical morphology of the catalyst is related to surface energy, crystal growth direction, and thermodynamic driving forces during crystallization. Solvent polarity, solubility, molecular structure, and solvation all affect the surface energy of the precipitate, thus influencing the crystallization orientation and final surface morphology during annealing. The presence of oxygen and increased temperature during annealing cause grain growth and rearrangement. Appropriate adjustment of the annealing temperature can control the grain morphology: when the temperature is too low, the crystallinity is low and no surface morphology is formed; while when the temperature is too high, grains can grow through grain merging, gradually reducing grain boundaries and ultimately forming larger grains or particles.
[0033] The ruthenium oxide oxygen evolution catalyst with a cone-shaped protrusion structure on its surface, prepared by the method provided by this invention, can be applied to the electrocatalytic oxygen evolution process.
[0034] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the range based on the description herein, and are not intended to be limited to the specific values in the examples below. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.
[0035] Example 1
[0036] The method for preparing the ruthenium oxide oxygen evolution catalyst with a cone-shaped protrusion structure on the surface provided in this embodiment includes the following steps: (1) Preparation of ruthenium precursor: Weigh RuCl3 powder, dissolve it in ethanol solution, and sonicate it for 20 min to prepare an ethanol solution of 44 g / L RuCl3; weigh urea powder, dissolve it in ethanol solution, and sonicate it for 20 min to prepare an ethanol solution of 19.5 g / L urea; then, add 6 mL of RuCl3 ethanol solution and 200 mL of urea ethanol solution to a three-necked flask, stir and heat at 65 °C for 3.5 h, then filter and wash 10 times, and place in a vacuum drying oven at 60 °C for 12 h to obtain ruthenium precursor; (2) Preparation of ruthenium oxide oxygen evolution catalyst with a cone-shaped protrusion structure on the surface: The ruthenium precursor described in step (1) is placed in a muffle furnace and calcined at 300°C for 3 hours in an air atmosphere with a heating rate of 3°C / min. After calcination, it is cooled to room temperature to obtain the ruthenium oxide oxygen evolution catalyst with a cone-shaped protrusion structure on the surface.
[0037] Comparative Example 1
[0038] The preparation method of the ruthenium oxide oxygen evolution catalyst provided in this comparative example is the same as that in Example 1, with the main difference being: In step (1), the solvent used for RuCl3 solution and urea solution is deionized water, and the heating temperature at normal pressure is 90℃.
[0039] Comparative Example 2
[0040] The preparation method of the ruthenium oxide oxygen evolution catalyst provided in this embodiment is the same as that in Example 1, with the main difference being: In step (2), the calcination temperature of the ruthenium precursor in air atmosphere is 200°C.
[0041] Figure 1This is the X-ray diffraction pattern of ruthenium oxide (RuO2) with a cone-shaped protrusion structure on its surface, prepared in Example 1 of this invention. As can be seen from the figure, its crystal phase is ruthenium oxide in the rutile phase.
[0042] Figure 2 This is a scanning electron microscope (SEM) image of the ruthenium oxide (RuO2) catalyst with a cone-shaped protrusion structure on its surface prepared in Example 1 of the present invention. As can be seen from the image, the surface of the ruthenium oxide oxygen evolution catalyst exhibits convex nano-tetrahedral pyramids.
[0043] Figure 3 This is a transmission electron microscope (TEM) image of the ruthenium oxide (RuO2) catalyst with a cone-shaped protrusion structure on its surface prepared in Example 1 of the present invention. As can be seen from the image, the ruthenium oxide oxygen evolution catalyst with a cone-shaped protrusion structure on its surface exhibits a cone shape.
[0044] Figure 4 This is a scanning electron microscope (SEM) image of ruthenium oxide (DI-RuO2) prepared in Comparative Example 1 of the present invention. As can be seen from the image, the surface of the ruthenium oxide (DI-RuO2) exhibits cubic protrusions.
[0045] Figure 5 This is a transmission electron microscope (TEM) image of ruthenium oxide (DI-RuO2) prepared in Comparative Example 1 of the present invention. As can be seen from the image, the ruthenium oxide (DI-RuO2) exhibits a cubic shape.
[0046] Figure 6 This is a scanning electron microscope (SEM) image of the ruthenium oxide prepared in Comparative Example 2 of the present invention. As can be seen from the image, the ruthenium oxide has a smooth surface without protrusions.
[0047] Figure 7 The figures show the anodic polarization curves of the oxygen evolution reaction (OER) of the ruthenium oxide (RuO2) catalyst with a cone-shaped protrusion structure prepared in Example 1 of this invention, the ruthenium oxide (DI-RuO2) prepared in Comparative Example 1, and the commercial RuO2 catalyst (Com-RuO2) and commercial IrO2 catalyst (Com-IrO2). As can be seen from the figures, the ruthenium oxide with a cone-shaped protrusion structure provided by this invention requires only 193 mV overpotential to reach 10 mA cm⁻¹. -2 The current density is significantly better than that of DI-RuO2 (217mV), Com-RuO2 (244mV), and Com-IrO2 (357mV).
[0048] Figure 8 This diagram illustrates the oxygen evolution reaction stability of the ruthenium oxide (RuO2) catalyst with a cone-shaped protrusion structure prepared in Example 1 of this invention, as well as commercial RuO2 catalysts (Com-RuO2) and (Com-IrO2). As can be seen from the figure, under a constant current of 10 mA / cm², the oxygen evolution reaction stability is... -2Under the specified conditions, the stability test conducted on carbon paper as a substrate showed a slight increase in voltage after 500 hours. In contrast, commercial RuO2 and IrO2 catalysts could only maintain stability for less than 1 hour and 30 hours, respectively, further demonstrating that this production method can enhance the stability of the material.
[0049] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.
Claims
1. A method for preparing a ruthenium oxide oxygen evolution catalyst with a surface exhibiting a cone-shaped protrusion structure, characterized in that, The preparation method includes the following steps: (1) Mix RuCl3 solution with urea solution and heat under normal pressure. After filtration, washing and drying, ruthenium precursor is obtained. (2) The ruthenium precursor is subjected to programmed heating and calcination, and after cooling, the ruthenium oxide oxygen evolution catalyst with a cone-shaped protrusion structure on the surface is obtained.
2. The preparation method according to claim 1, characterized in that, In step (1), the concentration of the RuCl3 solution is 20-50 g / L, and the concentration of the urea solution is 10-40 g / L; the volume ratio of the RuCl3 solution to the urea solution is 5-10:100-300.
3. The preparation method according to claim 1 or 2, characterized in that, In step (1), the atmospheric pressure heating is carried out in an oil bath; the heating temperature is 40-75℃, preferably 60-75℃, and the heating time is 2-5h, preferably 3-4h.
4. The preparation method according to any one of claims 1-3, characterized in that, In step (1), the number of times of filtration and washing is 5 to 15; the drying method is vacuum drying, the drying temperature is 50 to 100°C, and the drying time is 10 to 20 hours.
5. The preparation method according to any one of claims 1-4, characterized in that, Step (2) also includes a process for pre-treating the ruthenium precursor before calcination; wherein the pre-treatment process includes organic solvent cleaning, deionized water cleaning, drying and grinding.
6. The preparation method according to any one of claims 1-5, characterized in that, In step (2), the programmed temperature rise calcination is carried out in a muffle furnace, and the calcination atmosphere is air or argon atmosphere; the programmed temperature rise calcination temperature is 250-500℃, the calcination time is 1-5h, and the heating rate is 1-5℃ / min; preferably, the calcination temperature is 250-400℃, the calcination time is 2.5-3.5h, and the heating rate is 2.5-3.5℃ / min.
7. A ruthenium oxide oxygen evolution catalyst with a conical protrusion structure on its surface, obtained by the preparation method according to any one of claims 1-6, characterized in that, The ruthenium oxide oxygen evolution catalyst has a raised nano-tetrahedral pyramidal structure on its surface, with a specific surface area of 15-30 m². 2 / g.
8. The ruthenium oxide oxygen evolution catalyst with a conical protrusion structure on its surface according to claim 7, characterized in that, The ruthenium oxide oxygen evolution catalyst with a cone-shaped protrusion structure on its surface has a crystallization degree of 80-98% and a grain size of 5-30 nm.
9. The ruthenium oxide oxygen evolution catalyst with a conical protrusion structure on its surface according to claim 7 or 8, characterized in that, The ruthenium oxide oxygen evolution catalyst with a cone-shaped protrusion structure on its surface can reach an overpotential of 10 mA cm⁻¹ at an overpotential of 190-230 mV. -2 The current density can reach 100 mA / cm² at an overpotential of 250-300 mV. -2 The current density.
10. The application of a ruthenium oxide oxygen evolution catalyst with a conical protrusion structure on its surface according to any one of claims 7-9 in the electrocatalytic oxygen evolution process.