Preparation method of high-dispersity ruthenium dioxide nano material

Abstract

The invention discloses a preparation method of a high-dispersity ruthenium dioxide nano material, which comprises the following steps: dissolving ruthenium trichloride in deionized water, adding a surface modifier to form a uniform solution, dropwise adding a reducing agent under a stirring condition, and aging the solution for hours after the reduction reaction is completed to ensure the uniform distribution of ruthenium dioxide particles; and finally, carrying out centrifugal separation, washing and drying to obtain the high-dispersity ruthenium dioxide nano material. According to the method, by controlling the reduction conditions and using the surface modifier, the prepared ruthenium dioxide nano material has excellent dispersity and stability, the prepared ruthenium dioxide nano particles have the particle size of 100-250 nm, are high in dispersity, are not prone to agglomeration in a water phase and an organic solvent phase, are used in the fields of catalysis, electrochemical energy storage and the like, and have good application prospects. Compared with the prior art, the catalyst has the advantages that the catalytic activity can be remarkably improved, and the catalyst is suitable for fuel cells, supercapacitors and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of nanomaterials, and in particular relates to a method for preparing a highly dispersed ruthenium dioxide (RuO2) nanomaterial. Background Art

[0002] Ruthenium dioxide (RuO2) is a functional material with high catalytic activity, electrical conductivity and stability, which is widely used in electrochemical capacitors, electrocatalysts and sensors. Especially in fuel cells and supercapacitors, ruthenium dioxide has attracted much attention due to its excellent electrochemical performance and long cycle life.

[0003] However, the application of ruthenium dioxide is limited by the common agglomeration phenomenon during its material preparation process. Ruthenium dioxide nanoparticles are prone to agglomeration, which not only reduces their specific surface area, but also significantly reduces the number of their active sites, thus affecting their catalytic activity and stability in electrochemical reactions.

[0004] At present, the main methods for preparing ruthenium dioxide nanomaterials include chemical reduction, solvent thermal method and thermal decomposition method, etc. Although these methods can prepare ruthenium dioxide nanoparticles within a certain particle size range, they have the following shortcomings.

[0005] Poor particle dispersibility: In conventional chemical reduction methods, due to the lack of effective surface modification or dispersants, the ruthenium dioxide nanoparticles generated by the reaction will quickly agglomerate to form larger aggregates, resulting in a decrease in the specific surface area of ​​the material, which is not conducive to the performance of catalytic and electrochemical applications.

[0006] Particle size is difficult to control: Existing methods have certain challenges in controlling the particle size of ruthenium dioxide nanoparticles. The reaction conditions are not easy to accurately control, resulting in uneven particle size, which affects the consistency of material performance.

[0007] Complex preparation process: Solvothermal method and thermal decomposition method often require high reaction temperature and complex equipment, resulting in high production cost, complex process and difficulty in large-scale industrial production.

[0008] In order to overcome the above problems, in recent years, some studies have attempted to introduce surface modifiers (such as polyvinyl pyrrolidone PVP, sodium citrate, etc.) in the preparation process of ruthenium dioxide nanoparticles to improve the dispersibility of the particles. Surface modifiers can effectively inhibit the agglomeration of nanoparticles and form a stable dispersion system. However, this type of method still has the problem of high requirements for the amount of surface modifiers, and under certain conditions, it will affect the electrochemical properties of the material. Summary of the invention

[0009] The purpose of the present invention is to overcome the deficiencies of the prior art and provide an improved method for preparing a highly dispersible ruthenium dioxide nanomaterial.

[0010] The technical solution adopted by the present invention to solve the technical problem is: a method for preparing a highly dispersible ruthenium dioxide nanomaterial, the preparation process is as follows: (1) dissolving ruthenium trichloride at a concentration of 10 to 12.5 g / L in deionized water, adding a surface modifier at least twice the mass of ruthenium trichloride, and stirring to form a uniform solution; (2) adding a reducing agent in an amount of at least 1 times the mass of ruthenium trichloride dropwise to the solution under stirring at a temperature of 40 to 60° C., controlling the reduction reaction to last for 15 to 30 minutes, and gradually forming ruthenium dioxide nanoparticles with a particle size of 2 to 10 nm. The specific particle size can be achieved by adjusting the amount of the reducing agent and the reaction time; (3) aging the reaction product at a temperature of 50 to 60° C. for 1 to 3 hours to further improve the dispersibility of the particles; (4) removing the supernatant by centrifugal separation, washing the product with deionized water for 3 to 5 times, and then drying it in a vacuum drying oven at 50 to 80° C. for 8 to 12 hours to obtain a highly dispersed ruthenium dioxide nanomaterial with an average particle size of 100 to 250 nm.

[0011] Furthermore, the surface modifier is one or more of polyvinyl pyrrolidone (PVP), sodium citrate and amino acid compounds, preferably polyvinyl pyrrolidone.

[0012] Furthermore, the reducing agent is sodium borohydride or ascorbic acid, preferably sodium borohydride.

[0013] Furthermore, in the step (2), the stirring speed is 300-600 rpm to obtain a more uniform particle size.

[0014] Furthermore, in the step (4), centrifugation is performed at 3500-5000 rpm for 8-15 minutes.

[0015] The beneficial effects of the present invention are: The method of the present invention achieves the preparation of ruthenium dioxide nanoparticles with high dispersibility and uniform particle size by optimizing the use of reducing agents and surface modifiers and finely controlling reaction conditions; ruthenium dioxide nanomaterials with excellent dispersibility are prepared by a simple and easy redox method; through the surface modifier and appropriate reduction reaction conditions, the ruthenium dioxide nanoparticles are not easy to agglomerate and can maintain good dispersibility in different solution systems.

[0016] The method of the present invention adopts simple raw materials and equipment, mild reaction conditions, is suitable for large-scale preparation, and has high economic benefits; the prepared highly dispersed ruthenium dioxide nanomaterial has high electrical conductivity and electrochemical stability, and has broad application prospects in the fields of fuel cells, supercapacitors, etc.

[0017] The method of the present invention has the advantages of simple process, good dispersibility, stable particle size control, etc., and provides a new preparation method for the application of high-performance ruthenium dioxide materials in electrochemical fields such as fuel cells and capacitors. The method is suitable for the fields of catalysts, supercapacitors, fuel cells, etc., and has high catalytic activity and excellent electrochemical performance.

[0018] In summary, the present invention effectively improves the dispersibility and stability of ruthenium dioxide nanoparticles through an innovative preparation method, and is suitable for application fields requiring high catalytic activity and electrochemical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the XRD pattern of the ruthenium dioxide nanoparticles of Example 1 of the present invention; Figure 2 SEM image of ruthenium dioxide nanoparticles of Example 1 of the present invention; Figure 3 This is a laser particle size diagram of ruthenium dioxide nanoparticles in Example 1 of the present invention. DETAILED DESCRIPTION

[0020] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments. Example 1

[0021] The present embodiment discloses a method for preparing a highly dispersible ruthenium dioxide nanomaterial, comprising the following steps.

[0022] 1) Preparation of precursor solution.

[0023] Weigh 0.2 g of ruthenium trichloride and dissolve it in 20 mL of deionized water. Add 0.4 g of polyvinyl pyrrolidone (PVP, molecular weight of about 40,000) as a surface modifier to the solution under sufficient stirring, and continue stirring until the solution is completely clear and uniform. This step helps the ruthenium ions to disperse in the solution and prevents the agglomeration of particles during the subsequent generation process.

[0024] 2) Reduction reaction.

[0025] The precursor solution was placed on a stirring device and stirred at 300 rpm, and the reaction temperature was maintained at 25°C (room temperature). 0.2 g of sodium borohydride (NaBH) solution (pre-dissolved in 5 mL of deionized water) was added dropwise. The slow addition of the reducing agent helped control the nucleation rate of ruthenium dioxide, thereby obtaining smaller and uniform particles. The reaction time was controlled at 20 minutes, and a dark black suspension was generated, indicating the formation of ruthenium dioxide nanoparticles.

[0026] 3) Aging treatment.

[0027] The reduced product was aged in a thermostat at 50°C for 2 hours to promote the stabilization of the particle surface structure and ensure uniform distribution of the particles. This step can improve the stability of the particles and further improve the dispersion effect.

[0028] 4) Separation and purification.

[0029] The aged reaction mixture was centrifuged at a speed of 4000 rpm for 10 minutes. The precipitate was taken out and washed with deionized water three times to remove excess surface modifier and residual reactants. The washed precipitate was dried in a vacuum oven at 60°C for 12 hours to obtain a black powder of highly dispersed ruthenium dioxide nanomaterial.

[0030] Taking the product ruthenium dioxide nanomaterial of the present invention as an example, its structure is determined by X-ray diffractometer. Figure 1 As shown, the physical phase is completely consistent with the tetragonal RuO2 standard sample with card number 01-071-2273, which has sharp XRD diffraction peaks and no impurity peaks, good crystallinity, and an average particle size of 100 to 200 nm.

[0031] Figure 2 This is an SEM image of ruthenium dioxide nanomaterials. As shown in the figure, the obtained samples all present regular nanowire particles with an average particle size of 100 to 200 nm. Their high surface-to-volume ratio can increase the effective contact between the material and the slurry, provide efficient charge transfer, and reduce the diffusion path of ions / electrons.

[0032] Figure 3 This is a laser particle size image of ruthenium dioxide nanomaterials, indicating that its average particle size is 100-200nm, no large amount of agglomeration occurs, and the powder is evenly dispersed. Example 2

[0033] The steps of this embodiment are as follows: weigh 0.25 g of ruthenium trichloride and dissolve it in 20 mL of deionized water. Add 0.5 g of sodium citrate to the solution as a surface modifier and stir until completely dissolved to form a uniform precursor solution. Stir the precursor solution at 400 rpm at 40°C. Add 0.3 g of NaBH in water (5 mL) dropwise as a reducing agent, and the reaction time is controlled to 25 minutes. A dark suspension is observed to be generated, indicating the gradual generation of ruthenium dioxide nanoparticles. The product is aged at 60°C for 3 hours to further stabilize the structure of the particles. After the reaction is completed, the product is centrifuged at 5000 rpm for 10 minutes. After washing 4 times and removing excess material, the sample is dried in a vacuum drying oven at 70°C for 8 hours. SEM characterization shows that the average particle size of the product is 150 nm, the particle size distribution is uniform, and the dispersibility is good. Example 3

[0034] The steps of this embodiment are as follows: weigh 0.3 g of ruthenium trichloride and dissolve it in 20 mL of deionized water. Add 0.6 g of amino acid (glycine) as a surface modifier and stir thoroughly until the solution is transparent and uniform. Stir the solution at 500 rpm at 60°C, add 0.4 g of ascorbic acid (dissolved in 5 mL of water) dropwise as a reducing agent, the reaction time is 30 minutes, and the final solution is dark black. Age the mixture at 55°C for 2.5 hours. Centrifuge at a speed of 4500 rpm for 15 minutes and wash 5 times. The washed precipitate is dried in a vacuum drying oven at 80°C for 10 hours. SEM examination shows that the particle size of the product is about 100 nm, with good dispersibility and electrochemical stability. Example 4

[0035] The steps of this embodiment are as follows: weigh 0.15 g of ruthenium trichloride and dissolve it in 15 mL of deionized water. Add a mixture of 0.3 g PVP and 0.2 g sodium citrate as a surface modifier and stir until a uniform solution is obtained. Stir at 200 rpm at 25°C and add 0.15 g of NaBH solution dropwise. The reaction time is controlled to be 15 minutes. After the reaction is completed, a stable dark suspension is generated. Aging at 50°C for 1 hour promotes uniform distribution of particles. Centrifugal separation, centrifugal speed 3500 rpm, time 8 minutes, wash 3 times. Dry in a vacuum drying oven at 50°C for 10 hours. SEM characterization shows that the average particle size of the product is 250 nm, with good dispersibility, suitable for electrochemical applications.

[0036] The present invention can control the particle size of ruthenium dioxide nanoparticles to be between 100 and 250 nm by optimizing the addition amount of the reducing agent and the reaction conditions. The particle size is controllable to meet different application requirements, the process is simple, meets the requirements of green chemistry and is easy to scale up.

[0037] The experimental results of the above examples show that the preparation method of the present invention can achieve effective control of the particle size and dispersibility of ruthenium dioxide nanoparticles, provide high-performance materials for the electrochemical and catalytic fields, and is suitable for the fields of fuel cells, supercapacitors and electrochemical catalysts.

[0038] The above is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and changes without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for preparing a highly dispersible ruthenium dioxide nanomaterial, characterized in that: The steps are as follows (1) dissolving ruthenium trichloride at a concentration of 10 to 12.5 g / L in deionized water, adding a surface modifier at least twice the mass of ruthenium trichloride, and stirring to form a uniform solution; (2) adding a reducing agent at least 1 times the mass of ruthenium trichloride to the solution dropwise under stirring at 40-60° C., and continuing the reaction for 15-30 minutes to gradually form ruthenium dioxide nanoparticles with a particle size of 2-10 nm; (3) aging the reaction product at a temperature of 50 to 60° C. for 1 to 3 hours; (4) The supernatant is removed by centrifugal separation, and the product is washed with deionized water for 3 to 5 times, followed by drying in a vacuum drying oven at 50 to 80° C. for 8 to 12 hours to obtain a highly dispersed ruthenium dioxide nanomaterial with an average particle size of 100 to 250 nm.

2. The method for preparing a highly dispersible ruthenium dioxide nanomaterial according to claim 1, characterized in that: The surface modifier is one or more of polyvinyl pyrrolidone, sodium citrate and amino acid compounds.

3. The method for preparing a highly dispersible ruthenium dioxide nanomaterial according to claim 2, characterized in that: The reducing agent is sodium borohydride or ascorbic acid.

4. The method for preparing a highly dispersible ruthenium dioxide nanomaterial according to claim 1, 2 or 3, characterized in that: The stirring speed in step (2) is 300 to 600 rpm.

5. The method for preparing a highly dispersible ruthenium dioxide nanomaterial according to claim 1, 2 or 3, characterized in that: In the step (4), centrifugation is performed at 3500-5000 rpm for 8-15 minutes.

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