Preparation method of cubic silver particles in aqueous solution

Abstract

The invention relates to a method for preparing cubic silver particles in an aqueous solution, which comprises the following steps of: adding a certain amount of fudosteine aqueous solution into a reaction container, adding a silver nitrate aqueous solution into the reaction container, uniformly stirring, adjusting the pH value of the mixed solution to 10.0-10.5, then adding a glucose aqueous solution, stirring and reacting at the temperature of 60-75 DEG C, and performing solid-liquid separation on the product after the reaction is finished, thereby obtaining the cubic silver particles in the aqueous solution. And centrifugally washing the precipitate, and then drying in vacuum. The preparation method is carried out in a water-phase medium at a mild reaction temperature, alcohol solvents, high-temperature conditions and large-scale equipment are not needed, the process is simple, operation is easy and convenient, energy consumption is low, environment friendliness is achieved, and the prepared cubic silver particles are of a regular cubic structure, clear in corner angle, clear in geometric contour, uniform in particle size and suitable for large-scale production. The method has extremely high morphology consistency and narrow size distribution, and overcomes the defects that the reaction temperature is generally high and the requirement on reaction equipment is high in the existing preparation process.

Description

Technical Field

[0001] This invention belongs to the field of precious metal material preparation technology, specifically a method for preparing cubic silver particles in aqueous solution. Background Technology

[0002] Cubic Ag particles, with their sharp edges creating a "hotspot" effect, high specific surface area, tunable localized surface plasmon resonance (LSPR), and excellent conductivity and catalytic properties, have significant application value in fields such as optical sensing, antibacterial applications, high-efficiency catalysis, new energy technologies, and optoelectronic devices. For example, in the field of optical sensing, the "hotspots" generated by their sharp edges can amplify detection signals (such as Raman signals) by millions of times. Combined with their tunable plasmon resonance characteristics, ultrasensitive detection chips that respond to specific wavelengths of light can be designed.

[0003] Current methods for preparing cubic silver typically use alcohol solutions as solvents and reducing agents. Under high-temperature conditions (usually above 150°C), morphology-directing agents and stabilizers are added to reduce silver salt precursors such as silver nitrate, generating cubic silver nanoparticles. For example, patent CN 113579563 B discloses a nano-cubic silver solder paste, interconnect structure, and soldering method. Ethylene glycol is heated to 155-165°C and maintained for 1-1.5 h. Then, a catalyst solution, ligand solution, protective agent solution, and silver source precursor solution are added separately. The reaction is stirred at 155-165°C for 1-2 h, resulting in a suspension. The suspension is then separated into solid and liquid phases, centrifuged, washed, and dried to obtain nano-cubic silver particles. This patented preparation method requires a catalyst, ligand, and protective agent, and the reaction must be carried out at a high temperature of 155-165°C, resulting in high energy consumption. Patent CN 107552810B discloses a method for preparing nano-silver cubic particles. The method involves mixing a silver salt dispersion, a polyvinylpyrrolidone dispersion, and a hydrochloric acid dispersion, and reacting the mixture at 120-180℃ for 12-36 h to obtain nano-silver cubic particles. The solvent for each dispersion is at least one of ethylene glycol, diethylene glycol, and pentaerythritol. This technique requires reaction in an alcohol solvent, high-temperature reaction conditions, and a relatively long reaction time. Patent CN108372309 A discloses a method for preparing nano-silver cubes. The method involves mixing ethylene glycol and glycerol at a volume ratio of 1.5-1.8:1 to obtain a mixed solvent, then adding ferrous sulfide to obtain mixed solution A. Polyvinylpyrrolidone and tetraethylammonium bromide are dissolved in the ethylene glycol and glycerol mixed solvent to obtain mixed solution B. Mixed solution B is added to mixed solution A at a volume ratio of 1:1 to obtain mixed solution C. Silver nitrate is added to the ethylene glycol and glycerol mixed solvent to obtain mixed solution D. Mixed solution C and mixed solution D are mixed at a volume ratio of 1:1 to obtain mixed solution E. Mixed solution E is transferred to a microwave oven and reacted for 30-40 seconds, with a 12-15 minute pause in between, repeated 5-6 times. After completion, the mixture is centrifuged, washed, and dried to obtain nano-silver cubes. This technology involves extremely complex steps, requires microwave oven preparation, and places high demands on the equipment.

[0004] Currently, the mainstream method for preparing cubic Ag particles is liquid-phase chemical reduction, among which the polyol method is one of the most classic and widely used techniques. However, the polyol method is extremely sensitive to reaction conditions; even slight fluctuations can easily lead to the formation of various byproducts such as nanospheres, nanorods, and nanosheets, resulting in low yields and excessively wide size distributions of cubic Ag particles. This morphological inhomogeneity severely affects their optical properties and subsequent applications. Furthermore, the high-temperature reaction places high demands on equipment and consumes a lot of energy. Therefore, it is necessary to develop a mild and simple green method to prepare cubic silver particles with high uniformity. Summary of the Invention

[0005] To address the shortcomings of existing methods for preparing cubic silver, such as generally high reaction temperatures, demanding equipment requirements, and inconsistent morphology when using polyols as solvents, this invention provides a method for preparing cubic silver particles in aqueous solution. The aim is to simplify the preparation process, reduce the reaction temperature, and enable the preparation of cubic silver particles with uniform morphology, size, and sharp edges at lower temperatures and in a shorter time.

[0006] This invention is specifically achieved through the following technical solution: a method for preparing cubic silver particles in an aqueous solution according to this invention includes the following steps: 1) Weigh a certain amount of fodosteine ​​and add it to distilled water to prepare a fodosteine ​​aqueous solution with a concentration of 3.0-6.0 mol / L; 2) Weigh a certain amount of silver nitrate and add it to distilled water to prepare a silver nitrate aqueous solution with a concentration of 1.5-3.0 mol / L; 3) Weigh a certain amount of glucose and add it to distilled water to prepare a glucose aqueous solution with a concentration of 3.0-6.0 mol / L; 4) Take a certain amount of the fodosteine ​​aqueous solution prepared in step 1) and add it to the reaction vessel. Then add the silver nitrate aqueous solution prepared in step 2) to the reaction vessel. After stirring evenly, adjust the pH of the mixed solution to 10.0-10.5. Then add a certain amount of glucose aqueous solution prepared in step 3) to the reaction vessel and stir the reaction at 60-75℃. 5) After the reaction in step 4) is completed, the mixture is centrifuged and the resulting precipitate is washed by centrifugation and then dried under vacuum to obtain cubic silver particles.

[0007] In the aforementioned method for preparing cubic silver particles in aqueous solution, the solution used to adjust the pH in step 4) is an aqueous solution of sodium hydroxide.

[0008] Preferably, the concentration of the sodium hydroxide aqueous solution is 5.0 mol / L.

[0009] Preferably, the volume ratio of the aqueous solution of fodosteine, the aqueous solution of silver nitrate, and the aqueous solution of glucose added in step 4) is 3:1:1.

[0010] In the aforementioned method for preparing cubic silver particles in aqueous solution, step 4) involves stirring the reaction at 60-75°C for 0.5-2 h.

[0011] Preferably, in step 5), the obtained precipitate is centrifuged and washed with ultrapure water.

[0012] In the aforementioned method for preparing cubic silver particles in aqueous solution, step 5) involves vacuum drying at a temperature of 40-60℃ for 8-12 hours.

[0013] The aforementioned method for preparing cubic silver particles in aqueous solution produces cubic silver particles with a regular cubic structure. These cubic silver particles have clear edges and distinct geometric outlines, and their typical square faces, straight edges, and vertical corners can be clearly identified. The cubic silver particles have uniform particle size and size, with a side length of approximately 400 nm.

[0014] The present invention also provides cubic silver particles obtained by the aforementioned preparation method.

[0015] Compared with existing technologies, this invention has significant advantages and beneficial effects. Through the above technical solution, this invention achieves considerable technological advancement and practicality, and has broad application value, possessing at least the following advantages: (1) In this invention, water is used as the reaction medium, glucose as the reducing agent, and fodosteine ​​(i.e., R 2-Amino-3-(3-hydroxypropylthio)propionic acid was used as a structure-directing agent, and silver nitrate aqueous solution was used as a precursor solution. Glucose, as a mild reducing agent, reduced Ag... + The relatively slow reduction rate provides ample time for the directional growth of crystal nuclei, preventing the formation of irregularly shaped silver particles due to excessively rapid reduction. Because the entire reaction takes place in a homogeneous aqueous solution, the reactants, structure-directing agents, and reducing agents are uniformly distributed, and all crystal nuclei grow in nearly identical chemical environments, ensuring that the final product exhibits extremely high morphological consistency and a narrow size distribution.

[0016] (2) As can be seen from the magnified scanning electron microscope (SEM) image, the cubic silver particles prepared in this invention have a regular cubic structure. These cubic silver particles have clear edges and distinct geometric outlines, and their typical square faces, straight edges and vertical corners can be clearly identified. The cubic silver particles have uniform particle size and uniform dimensions, with a side length of about 400 nm.

[0017] (3) The technical route for preparing cubic silver particles in this invention is carried out in an aqueous phase at a mild reaction temperature (60-75℃). It does not require the addition of an additional strong reducing agent to the reaction system, does not require the use of alcohol solvents as reaction media, does not require high temperature reaction conditions, and does not require large heating equipment. The experimental conditions are mild, the process is simple, the operation is convenient, the energy consumption is low, the environment is friendly, the preparation process is short, and it is easy to operate and implement, which is in line with the principles of green chemistry. Attached Figure Description

[0018] Figure 1 This is a SEM image of the cubic silver particles prepared in Example 3, magnified 10,000 times.

[0019] Figure 2 This is a SEM image of the cubic silver particles prepared in Example 3, magnified 15,000 times.

[0020] Figure 3 This is a SEM image of the cubic silver particles prepared in Example 3, magnified 20,000 times. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The method for preparing cubic silver particles in aqueous solution provided by this invention specifically includes the following steps: 1) Weigh a certain amount of fodosteine ​​and add it to distilled water to prepare a fodosteine ​​aqueous solution with a concentration of 3.0-6.0 mol / L; 2) Weigh a certain amount of silver nitrate and add it to distilled water to prepare a silver nitrate aqueous solution with a concentration of 1.5-3.0 mol / L; 3) Weigh a certain amount of glucose and add it to distilled water to prepare a glucose aqueous solution with a concentration of 3.0-6.0 mol / L; 4) Take a certain amount of the fodosteine ​​aqueous solution prepared in step 1) and add it to the reaction vessel. Then add the silver nitrate aqueous solution prepared in step 2) to the reaction vessel. After stirring evenly, adjust the pH of the mixed solution to 10.0-10.5. Then add a certain amount of glucose aqueous solution prepared in step 3) to the reaction vessel and stir the reaction at 60-75℃ for 0.5-2 h. In this step, the preferred volume ratio of fodosteine ​​aqueous solution, silver nitrate aqueous solution, and glucose aqueous solution is 3:1:1; the solution used to adjust the pH can be, but is not limited to, a 5.0 mol / L sodium hydroxide aqueous solution; 5) After the reaction in step 4) is completed, the mixture is centrifuged and the resulting precipitate is washed with ultrapure water 3-6 times by centrifugation, and then vacuum dried at 40-60℃ for 8-12 h to obtain cubic silver particles.

[0023] The present invention will be further described below with specific embodiments. Unless otherwise specified, the conditions in the following embodiments are based on conventional conditions or conditions recommended by the manufacturer. Raw materials and reagents whose manufacturers are not specified are all commercially available products.

[0024] Example 1: 1) Weigh a certain amount of fodosteine ​​and add it to distilled water to prepare a fodosteine ​​aqueous solution with a concentration of 3.0 mol / L; 2) Weigh a certain amount of silver nitrate and add it to distilled water to prepare a silver nitrate aqueous solution with a concentration of 1.5 mol / L; 3) Weigh a certain amount of NaOH and add it to distilled water to prepare a NaOH aqueous solution with a concentration of 5.0 mol / L; 4) Weigh a certain amount of glucose and add it to distilled water to prepare a glucose aqueous solution with a concentration of 3.0 mol / L; 5) Take 300 mL of the fodosteine ​​aqueous solution prepared in step 1) and add it to a 1 L round-bottom flask. Add 100 mL of the silver nitrate aqueous solution prepared in step 2) to the round-bottom flask and stir well. Then add the NaOH aqueous solution prepared in step 3) to adjust the pH of the mixed solution to 10.0. Then add 100 mL of the glucose aqueous solution prepared in step 4) to the round-bottom flask and stir the reaction at 60℃ for 2 h. 6) After the reaction in step 5) is completed, the mixture is centrifuged and the supernatant is discarded. The precipitate is washed five times with ultrapure water by centrifugation and then dried under vacuum at 40°C for 12 h to obtain cubic silver particles.

[0025] Example 2: 1) Weigh a certain amount of fodosteine ​​and add it to distilled water to prepare a fodosteine ​​aqueous solution with a concentration of 4.0 mol / L; 2) Weigh a certain amount of silver nitrate and add it to distilled water to prepare a silver nitrate aqueous solution with a concentration of 1.5 mol / L; 3) Weigh a certain amount of NaOH and add it to distilled water to prepare a NaOH aqueous solution with a concentration of 5.0 mol / L; 4) Weigh a certain amount of glucose and add it to distilled water to prepare a glucose aqueous solution with a concentration of 4.0 mol / L; 5) Take 300 mL of the fodosteine ​​aqueous solution prepared in step 1) and add it to a 1 L round-bottom flask. Add 100 mL of the silver nitrate aqueous solution prepared in step 2) to the round-bottom flask and stir well. Then add the NaOH aqueous solution prepared in step 3) to adjust the pH of the mixed solution to 10.5. Then add 100 mL of the glucose aqueous solution prepared in step 4) to the round-bottom flask and stir the reaction at 60°C for 1.5 h. 6) After the reaction in step 5) is completed, the mixture is centrifuged and the supernatant is discarded. The precipitate is washed five times with ultrapure water by centrifugation and then dried under vacuum at 50°C for 12 h to obtain cubic silver particles.

[0026] Example 3: 1) Weigh a certain amount of fodosteine ​​and add it to distilled water to prepare a fodosteine ​​aqueous solution with a concentration of 4.8 mol / L; 2) Weigh a certain amount of silver nitrate and add it to distilled water to prepare a silver nitrate aqueous solution with a concentration of 2.0 mol / L; 3) Weigh a certain amount of NaOH and add it to distilled water to prepare a NaOH aqueous solution with a concentration of 5.0 mol / L; 4) Weigh a certain amount of glucose and add it to distilled water to prepare a glucose aqueous solution with a concentration of 3.0 mol / L; 5) Take 300 mL of the fodosteine ​​aqueous solution prepared in step 1) and add it to a 1 L round-bottom flask. Add 100 mL of the silver nitrate aqueous solution prepared in step 2) to the round-bottom flask and stir well. Then add the NaOH aqueous solution prepared in step 3) to adjust the pH of the mixed solution to 10.2. Then add 100 mL of the glucose aqueous solution prepared in step 4) to the round-bottom flask and stir the reaction at 75°C for 0.5 h. 6) After the reaction in step 5) is completed, the mixture is centrifuged and the supernatant is discarded. The precipitate is washed five times with ultrapure water by centrifugation and dried under vacuum at 60°C for 8 h to obtain cubic silver particles.

[0027] Figures 1-3 These are SEM images of the cubic silver particles prepared in this embodiment at different magnifications. As can be seen from the images, the prepared cubic silver particles exhibit a regular cubic structure. These cubic silver particles have clear edges and distinct geometric outlines, and their typical square faces, straight edges, and vertical corners can be clearly identified. The cubic silver particles have uniform particle size and dimensions, with a side length of approximately 400 nm.

[0028] Example 4: 1) Weigh a certain amount of fodosteine ​​and add it to distilled water to prepare a fodosteine ​​aqueous solution with a concentration of 6.0 mol / L; 2) Weigh a certain amount of silver nitrate and add it to distilled water to prepare a silver nitrate aqueous solution with a concentration of 3.0 mol / L; 3) Weigh a certain amount of NaOH and add it to distilled water to prepare a NaOH aqueous solution with a concentration of 5.0 mol / L; 4) Weigh a certain amount of glucose and add it to distilled water to prepare a glucose aqueous solution with a concentration of 6.0 mol / L; 5) Take 300 mL of the fodosteine ​​aqueous solution prepared in step 1) and add it to a 1 L round-bottom flask. Add 100 mL of the silver nitrate aqueous solution prepared in step 2) to the round-bottom flask and stir well. Then add the NaOH aqueous solution prepared in step 3) to adjust the pH of the mixed solution to 10.0. Then add 100 mL of the glucose aqueous solution prepared in step 4) to the round-bottom flask and stir the reaction at 70°C for 1 h. 6) After the reaction in step 5) is completed, the mixture is centrifuged and the supernatant is discarded. The precipitate is washed five times with ultrapure water by centrifugation and then dried under vacuum at 50°C for 10 h to obtain cubic silver particles.

[0029] Example 5: 1) Weigh a certain amount of fodosteine ​​and add it to distilled water to prepare a fodosteine ​​aqueous solution with a concentration of 5.0 mol / L; 2) Weigh a certain amount of silver nitrate and add it to distilled water to prepare a silver nitrate aqueous solution with a concentration of 2.0 mol / L; 3) Weigh a certain amount of NaOH and add it to distilled water to prepare a NaOH aqueous solution with a concentration of 5.0 mol / L; 4) Weigh a certain amount of glucose and add it to distilled water to prepare a glucose aqueous solution with a concentration of 5.0 mol / L; 5) Take 300 mL of the fodosteine ​​aqueous solution prepared in step 1) and add it to a 1 L round-bottom flask. Add 100 mL of the silver nitrate aqueous solution prepared in step 2) to the round-bottom flask and stir well. Then add the NaOH aqueous solution prepared in step 3) to adjust the pH of the mixed solution to 10.2. Then add 100 mL of the glucose aqueous solution prepared in step 4) to the round-bottom flask and stir the reaction at 60°C for 2 h. 6) After the reaction in step 5) is completed, the mixture is centrifuged and the supernatant is discarded. The precipitate is washed five times with ultrapure water by centrifugation and then dried under vacuum at 50°C for 10 h to obtain cubic silver particles.

[0030] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. The present invention can also have other embodiments based on the above structure and function, which will not be listed hereafter. Therefore, any simple modifications, equivalent changes, and alterations made by those skilled in the art to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing cubic silver particles in an aqueous solution, characterized in that, Includes the following steps: 1) Weigh a certain amount of fodosteine ​​and add it to distilled water to prepare a fodosteine ​​aqueous solution with a concentration of 3.0-6.0 mol / L; 2) Weigh a certain amount of silver nitrate and add it to distilled water to prepare a silver nitrate aqueous solution with a concentration of 1.5-3.0 mol / L; 3) Weigh a certain amount of glucose and add it to distilled water to prepare a glucose aqueous solution with a concentration of 3.0-6.0 mol / L; 4) Take a certain amount of the fodosteine ​​aqueous solution prepared in step 1) and add it to the reaction vessel. Then add the silver nitrate aqueous solution prepared in step 2) to the reaction vessel. After stirring evenly, adjust the pH of the mixed solution to 10.0-10.

5. Then add a certain amount of glucose aqueous solution prepared in step 3) to the reaction vessel and stir the reaction at 60-75℃. 5) After the reaction in step 4) is completed, the mixture is centrifuged and the resulting precipitate is washed by centrifugation and then dried under vacuum to obtain cubic silver particles.

2. The method for preparing cubic silver particles in aqueous solution as described in claim 1, characterized in that, The solution used to adjust the pH in step 4) is an aqueous solution of sodium hydroxide.

3. The method for preparing cubic silver particles in aqueous solution as described in claim 2, characterized in that, The concentration of the sodium hydroxide aqueous solution is 5.0 mol / L.

4. The method for preparing cubic silver particles in aqueous solution as described in claim 1, characterized in that, The volume ratio of the aqueous solution of fodosteine, the aqueous solution of silver nitrate, and the aqueous solution of glucose added in step 4) is 3:1:

1.

5. The method for preparing cubic silver particles in aqueous solution as described in claim 1, characterized in that, In step 4), the stirring reaction time at 60-75℃ is 0.5-2 h.

6. The method for preparing cubic silver particles in aqueous solution as described in claim 1, characterized in that, In step 5), the precipitate is washed by centrifugation with ultrapure water.

7. The method for preparing cubic silver particles in aqueous solution as described in claim 1, characterized in that, In step 5), the vacuum drying temperature is 40-60℃ and the time is 8-12 h.

8. The method for preparing cubic silver particles in aqueous solution as described in claim 1, characterized in that, The resulting cubic silver particles have a regular cubic structure and a side length of 400 nm.

9. Cubic silver particles obtained by any of the preparation methods described in claims 1-7.

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