Small-sized ruthenium dioxide nanoparticles, preparation method and application thereof

Abstract

The application discloses small-size ruthenium dioxide nanoparticles and a preparation method and application thereof, and relates to the technical field of catalysts. The preparation method comprises the following steps: dissolving a ruthenium chloride precursor salt into deionized water, adding a carbon carrier, stirring to obtain a uniform solution, removing the aqueous solution through a rotary evaporator to obtain a dry ruthenium chloride material loaded on the carbon carrier, grinding the material into loose powder, and performing calcination under a reducing atmosphere to obtain metal ruthenium nanoparticles loaded on the carbon carrier; then, the metal ruthenium nanoparticles are calcined under an air atmosphere to remove the carbon carrier; finally, the metal ruthenium nanoparticles are ground to obtain uniformly dispersed ruthenium dioxide nanoparticle material. The preparation process flow is simple, a complex auxiliary system is not needed, the method has the advantages of strong controllability and good repeatability, and is suitable for large-scale production. The obtained product is small-size pure-phase ruthenium dioxide nanoparticles with high dispersion and uniform particle size, and can be used as a high-performance catalyst and applied to an acid electrolysis water oxygen evolution catalytic reaction.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a small-sized ruthenium dioxide nanoparticle, its preparation method, and its application. Background Technology

[0002] Proton exchange membrane electrolysis (PEMWE) technology is the most attractive among all water electrolysis technologies due to its high proton conductivity, low gas permeability, high current density, high-purity hydrogen, high efficiency, fast response, high-pressure operation capability, and compact structure. However, the oxygen evolution reaction (OER) electrocatalyst in PEMWE needs to operate in harsh environments with high acidity, high potential, and strong oxidizing properties, which places high demands on the catalyst's activity and stability. Currently, iridium (Ir)-based catalysts remain the only practical OER electrocatalysts for PEMWE due to their excellent durability and good activity. However, the scarcity and high cost of iridium restrict the large-scale application and sustainable development of PEMWE. Therefore, developing more inexpensive and readily available, highly active, and highly stable non-iridium-based acidic oxygen evolution reaction electrocatalysts has become an important research direction.

[0003] Among numerous precious metal catalysts, ruthenium (Ru) has attracted widespread attention due to its relatively abundant reserves, lower cost than iridium, and high activity. As an oxide of ruthenium (Ru), ruthenium dioxide possesses high catalytic activity, high electrical conductivity, and high specific surface capacitance, making it a highly promising OER catalyst. To further enhance the catalytic activity of ruthenium dioxide, methods such as size reduction, elemental doping, and the construction of composite supports can be employed. Among these, reducing the size of ruthenium dioxide through microstructural control to prepare nanoscale ruthenium dioxide can effectively increase the active specific surface area, expose more edge active sites, and thus improve the intrinsic activity and stability of ruthenium dioxide. Currently, the main methods for preparing nanoscale ruthenium dioxide include thermal decomposition, sol-gel, hydrothermal, and molten salt methods. Different methods exhibit different advantages and disadvantages, but they generally suffer from problems such as complex synthesis methods, low preparation efficiency, difficulty in solid-liquid separation, large particle size, and non-uniform particle size.

[0004] For example, Chinese invention patent CN121826757A discloses a small-sized ruthenium dioxide nanomaterial, its preparation method, and its application. It involves etching, cleaning, and drying a titanium sheet in an oxalic acid solution to create a substrate. Sodium bromide is added to a ruthenium dioxide precursor solution as a size control agent. After mixing, drying, and calcination, ruthenium dioxide nanocrystals with significantly reduced particle size are obtained. However, this patent relies on external additives to control the grain size, and the product is bound to the titanium sheet, making it impossible to obtain free ruthenium dioxide powder, thus limiting its application scenarios.

[0005] Chinese invention patent CN115818740A discloses a method for synthesizing ruthenium dioxide nanopowder. The method involves dissolving ruthenium chloride raw material in deionized water, adjusting the pH of the system with an acid solution to obtain a ruthenium chloride solution, then adding H₂O₂ solution or NaClO solution dropwise and heating the solution. After aging, centrifugation, washing, and drying, black ruthenium dioxide solid is obtained. Finally, the solid is ground and calcined to obtain ruthenium dioxide nanopowder. This invention uses H₂O₂ or NaClO as an oxidant to directly synthesize ruthenium dioxide nanopowder. 3+ The oxidation process generates RuO2 precipitate, which is then calcined. The nucleation density depends on the oxidant droplet acceleration rate and local concentration, making it difficult to control. The resulting ruthenium dioxide nanoparticles are relatively large in size.

[0006] Chinese invention patent CN110137510A discloses a method for preparing nano-ruthenium dioxide and its application. The method involves dissolving ruthenium trichloride in ethanol to prepare a ruthenium trichloride ethanol solution, followed by ultrasonication to obtain a hydrothermal solution. This solution is then subjected to a hydrothermal reaction at 150–200°C for 6–12 hours. After washing, drying, and calcination, nano-ruthenium dioxide is obtained. This patent obtains nano-ruthenium dioxide through a single-phase hydrothermal direct oxidation method. Relying on hydrothermal temperature and reaction time to control grain morphology and size may lead to problems such as uneven grain size and localized agglomeration, limiting batch-to-batch reproducibility.

[0007] Therefore, there is a need to develop a small-sized ruthenium dioxide nanoparticle and its preparation method that has a simple process flow, does not require a complex auxiliary system, has strong controllability, good repeatability, and is suitable for large-scale production. This is of great value for improving the catalytic activity and long-term stability of ruthenium-based electrocatalysts and promoting the industrialization of proton exchange membrane water electrolysis technology. Summary of the Invention

[0008] The purpose of this invention is to address the aforementioned problems by providing small-sized ruthenium dioxide nanoparticles, their preparation method, and applications. This invention overcomes the shortcomings of existing technologies that often rely on complex auxiliary systems such as acid-base regulation, exogenous reducing agents, or organic solvents. The preparation process is simple, requires no complex auxiliary systems, and has the advantages of strong controllability and good repeatability, making it suitable for large-scale production. The resulting product is highly dispersed, uniformly sized, pure-phase ruthenium dioxide nanoparticles.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: According to a first aspect of the present invention, a method for preparing small-sized ruthenium dioxide nanoparticles is provided, comprising the following steps: S1. Dissolve the ruthenium chloride precursor salt in deionized water, add a carbon support, and stir to obtain a homogeneous solution; S2. The mixed solution obtained in S1 is subjected to rotary evaporation to remove the aqueous solution, thereby obtaining a dry ruthenium chloride material supported on a carbon support; S3. Grind the material obtained in S2 into a loose powder, and then calcine it under a reducing atmosphere to reduce ruthenium chloride and obtain metallic ruthenium nanoparticles supported on a carbon support. S4. Calcine the material obtained in S3 in an air atmosphere to remove the carbon support; S5. Grind the material treated in S4 to obtain uniformly dispersed ruthenium dioxide nanoparticles.

[0010] Alternatively, the carbon support of S1 may be at least one of carbon black, graphene, carbon nanotubes, carbon nanospheres, porous carbon, or biochar.

[0011] Alternatively, the mass ratio of ruthenium chloride precursor salt to carbon support in S1 is 1:(5-20).

[0012] Alternatively, the stirring time in S1 can be 1 to 6 hours.

[0013] Alternatively, the rotary evaporation process in S2 can be carried out at a temperature of 60–80°C, a pressure of 50–200 bar, and a time of 2–4 h.

[0014] Alternatively, the calcination temperature in S3 can be 200–400°C, and the calcination time can be 2–4 h.

[0015] Alternatively, the reducing atmosphere in S3 may be a hydrogen-argon mixture atmosphere, wherein the proportion of hydrogen is 4% to 10%.

[0016] Alternatively, the calcination temperature in S4 is 400–600°C, and the calcination time is 2–4 h.

[0017] According to a second aspect of the present invention, small-sized ruthenium dioxide nanoparticles are provided, which are prepared by any of the preparation methods described above.

[0018] According to a third aspect of the present invention, the application of the above-described small-sized ruthenium dioxide nanoparticles in a proton exchange membrane electrolyzer is provided.

[0019] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. The present invention provides a small-sized ruthenium dioxide nanoparticle, its preparation method, and its application. This invention overcomes the shortcomings of existing technologies that often rely on complex auxiliary systems such as acid-base regulation, exogenous reducing agents, or organic solvents. The preparation process is simple, requires no complex auxiliary systems, and has the advantages of strong controllability and good reproducibility, making it suitable for large-scale production. The obtained product is highly dispersed, uniformly sized, pure-phase ruthenium dioxide nanoparticles, which can serve as a high-performance catalyst suitable for the oxygen evolution reaction in acidic water electrolysis. Its excellent catalytic performance demonstrates promising practical applications.

[0020] 2. The present invention provides a small-sized ruthenium dioxide nanoparticle, its preparation method, and its application. First, a pure water impregnation combined with rotary evaporation is used to achieve uniform loading of the ruthenium precursor on a carbon support. Then, pre-reduction is performed under a low-temperature hydrogen-argon atmosphere to reduce the ruthenium precursor in situ into uniform metallic ruthenium nuclei, achieving pre-shaping of the crystals and completely removing chloride ion impurities. Finally, ruthenium dioxide is generated through high-temperature in-situ oxidation, while simultaneously removing the carbon support. Based on the above step-by-step control mechanism, highly dispersed ruthenium dioxide nanoparticles with uniform particle size are finally obtained. Attached Figure Description

[0021] The present invention will be described by way of example and with reference to the accompanying drawings, wherein: Figure 1 This is a transmission electron microscope image of Example 1; Figure 2 This is a high-resolution transmission electron microscope image of Example 1; Figure 3 This is a transmission electron microscope image of Example 2; Figure 4 This is a high-resolution transmission electron microscope image of Example 2; Figure 5 This is a transmission electron microscope image of Example 3; Figure 6 This is a high-resolution transmission electron microscope image of Example 3; Figure 7 This is a transmission electron microscope image of Example 4; Figure 8 This is a high-resolution transmission electron microscope image of Example 4; Figure 9 The XRD patterns are those of Examples 1-3; Figure 10 The graphs show the polarization curves of the PEM electrolyzers in Examples 1-3. Figure 11 This is a long-term performance test diagram of the PEM electrolyzer in Example 1. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings.

[0023] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0024] Any feature disclosed in this specification, unless otherwise stated, may be replaced by other equivalent or similar features. That is, unless otherwise stated, each feature is merely one example of a series of equivalent or similar features.

[0025] Example 1 Small-sized ruthenium dioxide nanoparticles were prepared using the following method: S1. Dissolve the ruthenium chloride precursor salt in deionized water, add carbon black, and add ruthenium chloride to carbon black in a mass ratio of 1:5. Stir at room temperature for 2 hours to obtain a homogeneous solution.

[0026] S2. The mixed solution obtained in S1 is transferred to a rotary evaporator and evaporated at 65°C and 100 bar for 2 hours to remove the aqueous solution, obtaining dry ruthenium chloride material loaded on a carbon support. The carbon support is used to disperse the ruthenium chloride, preventing its reduction to bulk metallic ruthenium. Simultaneously, a combination of pure water impregnation and rotary evaporation is used to achieve uniform loading of the ruthenium precursor on the carbon support.

[0027] S3. The material obtained in S2 is ground into a loose powder and then placed in a tube furnace for calcination in a hydrogen-argon mixed atmosphere (hydrogen ratio of 10%). The heating rate is 5℃ / min, the calcination temperature is 200℃, and the calcination time is 2 h. Ruthenium chloride is reduced to obtain metallic ruthenium nanoparticles supported on a carbon support. Using a hydrogen-argon mixed atmosphere reduces the risk of using pure hydrogen and facilitates operation. Pre-reduction is performed in a low-temperature hydrogen-argon atmosphere to reduce the ruthenium precursor in situ into uniform metallic ruthenium nuclei, achieving pre-shaping of the grains and completely removing chloride ion impurities.

[0028] S4. The material obtained in S3 is calcined in air at a temperature of 400℃ for 2 hours. High-temperature in-situ oxidation produces ruthenium dioxide, while simultaneously removing the carbon support.

[0029] S5. Grind the material treated in S4 to obtain uniformly dispersed ruthenium dioxide nanoparticles.

[0030] Transmission electron microscope image of the small-sized ruthenium dioxide nanoparticles prepared is shown below. Figure 1 High-resolution transmission electron microscope image (see) Figure 2 The ruthenium dioxide nanoparticles prepared in this embodiment are uniformly dispersed, with a particle size between 4-7 nm and an average particle size of 5.8 nm. The long-term performance of the ruthenium dioxide nanoparticles prepared in this embodiment with that of commercial RuO2 in a PEM electrolyzer is compared; the test results are shown in [Figure number missing]. Figure 11 As can be seen, the RuO2 catalyst prepared in this embodiment can operate stably for 500 h with a stable voltage curve, exhibiting excellent stability. In contrast, commercial RuO2 shows a significant increase in operating voltage within 1 h, and its activity rapidly declines, with catalytic activity and stability far lower than that of the RuO2 catalyst prepared in this embodiment.

[0031] Example 2 Small-sized ruthenium dioxide nanoparticles were prepared using the same preparation steps as in Example 1, with the only difference being that the ratio of ruthenium chloride to carbon black was 1:10 by mass, while all other conditions remained unchanged.

[0032] Transmission electron microscope image of the small-sized ruthenium dioxide nanoparticles prepared is shown below. Figure 3 High-resolution transmission electron microscope image (see) Figure 4 The ruthenium dioxide nanoparticles prepared in this embodiment have a particle size mainly distributed between 4 and 8 nm, with a small number of particles larger than 10 nm, and an average particle size of 6.58 nm.

[0033] Example 3 Small-sized ruthenium dioxide nanoparticles were prepared using the same preparation steps as in Example 1, with the only difference being that the ratio of ruthenium chloride to carbon black was 1:20 by mass, while all other conditions remained unchanged.

[0034] Transmission electron microscope image of the small-sized ruthenium dioxide nanoparticles prepared is shown below. Figure 5 High-resolution transmission electron microscope image (see) Figure 6 The ruthenium dioxide nanoparticles prepared in this embodiment are uniformly dispersed, with a particle size distribution between 12-20 nm and an average particle size of 15.36 nm.

[0035] Analysis of Examples 1-3 shows that the size of ruthenium dioxide nanoparticles can be adjusted by changing the ratio of ruthenium chloride to carbon black. In Example 1, the mass ratio of ruthenium chloride to carbon black was 1:5, resulting in the smallest particle size of the ruthenium dioxide nanoparticles. Figure 9 The XRD patterns of Examples 1-3 show that Example 1 has a higher degree of crystallinity. Figure 10 The graphs show the polarization curves of the PEM electrolyzers for Examples 1-3. Under the same current density, the ruthenium dioxide nanoparticles prepared in Example 1 have a lower cell voltage and exhibit superior catalytic performance.

[0036] Example 4 Small-sized ruthenium dioxide nanoparticles were prepared using the same preparation steps as in Example 1, with the only difference being that the calcination temperature in air atmosphere in S4 was 500°C, while the other conditions remained unchanged.

[0037] Transmission electron microscope image of the small-sized ruthenium dioxide nanoparticles prepared is shown below. Figure 7 High-resolution transmission electron microscope image (see) Figure 8 The ruthenium dioxide nanoparticles prepared in this embodiment are uniformly dispersed, with a particle size between 6 and 11 nm and an average particle size of 8.65 nm.

[0038] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. The present invention provides a small-sized ruthenium dioxide nanoparticle, its preparation method, and its application. This invention overcomes the shortcomings of existing technologies that often rely on complex auxiliary systems such as acid-base regulation, exogenous reducing agents, or organic solvents. The preparation process is simple, requires no complex auxiliary systems, and has the advantages of strong controllability and good reproducibility, making it suitable for large-scale production. The obtained product is highly dispersed, uniformly sized, pure-phase ruthenium dioxide nanoparticles, which can serve as a high-performance catalyst suitable for the oxygen evolution reaction in acidic water electrolysis. Its excellent catalytic performance demonstrates promising practical applications.

[0039] 2. The present invention provides a small-sized ruthenium dioxide nanoparticle, its preparation method, and its application. First, a pure water impregnation combined with rotary evaporation is used to achieve uniform loading of the ruthenium precursor on a carbon support. Then, pre-reduction is performed under a low-temperature hydrogen-argon atmosphere to reduce the ruthenium precursor in situ into uniform metallic ruthenium nuclei, achieving pre-shaping of the crystals and completely removing chloride ion impurities. Finally, ruthenium dioxide is generated through high-temperature in-situ oxidation, while simultaneously removing the carbon support. Based on the above step-by-step control mechanism, highly dispersed ruthenium dioxide nanoparticles with uniform particle size are finally obtained.

[0040] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A method for preparing small-sized ruthenium dioxide nanoparticles, characterized in that, Includes the following steps: S1. Dissolve the ruthenium chloride precursor salt in deionized water, add a carbon support, and stir to obtain a homogeneous solution; S2. The mixed solution obtained in S1 is subjected to rotary evaporation to remove the aqueous solution, thereby obtaining a dry ruthenium chloride material supported on a carbon support; S3. Grind the material obtained in S2 into a loose powder, and then calcine it under a reducing atmosphere to reduce ruthenium chloride and obtain metallic ruthenium nanoparticles supported on a carbon support. S4. Calcine the material obtained in S3 in an air atmosphere to remove the carbon support; S5. Grind the material treated in S4 to obtain uniformly dispersed ruthenium dioxide nanoparticles.

2. The method for preparing small-sized ruthenium dioxide nanoparticles as described in claim 1, characterized in that, The carbon support of S1 is at least one of carbon black, graphene, carbon nanotubes, carbon nanospheres, porous carbon, or biochar.

3. The method for preparing small-sized ruthenium dioxide nanoparticles as described in claim 1, characterized in that, The mass ratio of ruthenium chloride precursor salt to carbon support in S1 is 1:(5-20).

4. The method for preparing small-sized ruthenium dioxide nanoparticles as described in claim 1, characterized in that, The stirring time in S1 is 1 to 6 hours.

5. The method for preparing small-sized ruthenium dioxide nanoparticles as described in claim 1, characterized in that, The rotary evaporation process in S2 is carried out at a temperature of 60–80°C, a pressure of 50–200 bar, and a time of 2–4 h.

6. The method for preparing small-sized ruthenium dioxide nanoparticles as described in claim 1, characterized in that, The calcination temperature in S3 is 200–400℃, and the calcination time is 2–4 h.

7. The method for preparing small-sized ruthenium dioxide nanoparticles as described in claim 1, characterized in that, The reducing atmosphere in S3 is a hydrogen-argon mixture atmosphere, wherein the proportion of hydrogen is 4% to 10%.

8. The method for preparing small-sized ruthenium dioxide nanoparticles as described in claim 1, characterized in that, The calcination temperature in S4 is 400–600℃, and the calcination time is 2–4 h.

9. A small-sized ruthenium dioxide nanoparticle, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the small-sized ruthenium dioxide nanoparticles as described in claim 9 in a proton exchange membrane electrolyzer.

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