Micron-sized flower-ball silver powder with adjustable surface roughness and preparation method of micron-sized flower-ball silver powder

Abstract

The invention belongs to the technical field of silver powder preparation, and particularly relates to micron-sized flower-ball silver powder with adjustable surface roughness and a preparation method thereof.The preparation method comprises the steps that a dodecyl glucoside aqueous solution with a certain concentration is added into a silver nitrate aqueous solution, stirring and mixing are conducted, then an ascorbic acid aqueous solution is added, stirring reaction is conducted for 1-2 h, and after solid-liquid separation is conducted on a product, the micron-sized flower-ball silver powder with adjustable surface roughness is obtained; and centrifugally washing the precipitate, and drying in vacuum to obtain the product. The preparation method is simple in process, easy and convenient to operate, mild in condition, green in raw material and short in preparation process, and the prepared silver powder particles have highly-regular ball-flower-shaped structures, rough in surface, obvious in three-dimensional structural characteristics, free of obvious agglomeration or structural defects, good in dispersity, uniform in particle size distribution and high in purity and crystallinity. By regulating and controlling the reactant concentration and the stirring speed, the ball-flower silver powder which is uniform in particle size and different in surface roughness can be effectively regulated and controlled to be synthesized.

Description

Technical Field

[0001] This invention belongs to the field of metal powder preparation technology, specifically relating to a micron-sized flower-shaped silver powder with adjustable surface roughness and its preparation method. Background Technology

[0002] Three-dimensional flower-shaped silver powder has attracted widespread attention due to its high specific surface area, porous structure, good dispersibility, and conductivity. The rough surface of flower-shaped silver powder can form numerous "hot spots." As the surface roughness of the powder increases, the surface curvature, tips, and defects of the silver nanostructures increase, resulting in a significant enhancement of the surface-enhanced Raman scattering (SERS) effect. Furthermore, by controlling the particle size distribution and surface roughness of the silver powder, its performance in fields such as photovoltaic silver paste grid line printing, fuel cell catalyst supports, and conductive adhesives for 5G RF devices can be directionally optimized.

[0003] Common methods for synthesizing flower-shaped silver powder include the template method and the chemical reduction method. The template method often uses silica (SiO2) microspheres or nanorods as templates, deposits silver ions on the template surface, and then dissolves the template with hydrofluoric acid (HF) to obtain flower-shaped silver powder. The template method can precisely control the size and porosity of the flower-shaped structure, but the template removal process may introduce impurities, and HF is highly corrosive.

[0004] Chinese invention patent CN 118976906 A attempted to prepare flower-shaped silver powder using a chemical reduction method. First, a silver nitrate solution was prepared, followed by a mixed solution consisting of a reducing agent, pH adjuster, dispersant, and surfactant. These two solutions were then mixed to prepare flower-shaped silver powder. However, SEM images revealed a significant size variation and wide particle size distribution in the flower-shaped silver powder. Chinese invention patent CN 107127355 A used ammoniacal silver solution as a precursor, sodium hydroxide solution as a pH adjuster, and cysteine ​​or reduced glutathione as a reducing agent and surfactant to prepare flower-shaped silver powder. However, both contain thiol groups (-SH) in their molecular structure. This group interacts very strongly with silver, easily forming Ag-S bonds, making it difficult to completely remove from the product surface. Furthermore, the reaction steps are complex and the reaction time is long (approximately 5.0-10.0 h), which undoubtedly reduces efficiency. Therefore, it is necessary to develop a simple, efficient, and green method to prepare flower-shaped silver powder with good dispersibility, uniform particle size, and adjustable surface roughness in one step. Summary of the Invention

[0005] This invention provides a micron-sized flower-shaped silver powder with adjustable surface roughness and its preparation method. The purpose is to simplify the silver powder preparation process, shorten the preparation cycle, achieve green preparation, and at the same time prepare a flower-shaped silver powder with good dispersibility, high purity, uniform particle size distribution, and adjustable surface roughness.

[0006] This invention is specifically achieved through the following technical solution: a method for preparing micron-sized flower ball silver powder with adjustable surface roughness, according to this invention, includes the steps of preparing a precursor solution, preparing a bio-based surfactant solution, preparing a reducing agent solution, performing liquid-phase reduction after mixing, and separating and purifying the reaction product. The precursor is silver nitrate, the bio-based surfactant is dodecyl glucoside, and the reducing agent is ascorbic acid. The specific steps include: (1) Weigh a certain amount of silver nitrate and add it to deionized water. Stir until completely dissolved to prepare a silver nitrate aqueous solution with a concentration of 50-100 mmol / L for later use. (2) Weigh a certain amount of dodecyl glucoside and add it to deionized water. Stir until completely dissolved to prepare an aqueous solution of dodecyl glucoside with a concentration of 100-300 mmol / L for later use. (3) Weigh a certain amount of ascorbic acid and add it to deionized water. Stir until completely dissolved to prepare an ascorbic acid aqueous solution with a concentration of 200-600 mmol / L for later use. (4) Add the silver nitrate aqueous solution prepared in step (1) to the reaction vessel. Under stirring conditions, quickly add the dodecyl glucoside aqueous solution prepared in step (2) to the reaction vessel and stir for 5-15 min to obtain a mixed solution. Quickly add the ascorbic acid aqueous solution prepared in step (3) to the obtained mixed solution and stir for 1-2 h. (5) After stirring and reacting in step (4), the mixture is separated into solid and liquid phases. The precipitate is washed with deionized water by centrifugation 3-5 times and then vacuum dried to obtain micron-sized flower ball silver powder with adjustable surface roughness.

[0007] In the aforementioned method for preparing micron-sized flower ball silver powder with adjustable surface roughness, the molar ratio of silver nitrate to dodecyl glucoside in step (4) is 1:(1-5).

[0008] In the aforementioned method for preparing micron-sized flower ball silver powder with adjustable surface roughness, the molar ratio of silver nitrate to ascorbic acid in step (4) is 1:(2-4).

[0009] In the aforementioned method for preparing micron-sized flower ball silver powder with adjustable surface roughness, the volume ratio of silver nitrate aqueous solution, dodecyl glucoside aqueous solution, and ascorbic acid aqueous solution in step (4) is 2:2:1.

[0010] In the aforementioned method for preparing micron-sized flower ball silver powder with adjustable surface roughness, the stirring speed in step (4) is 300-600 r / min.

[0011] In the aforementioned method for preparing micron-sized flower ball silver powder with adjustable surface roughness, the vacuum drying temperature in step (5) is 40-60℃ and the time is 10-24 h.

[0012] The aforementioned method for preparing micron-sized flower-shaped silver powder with adjustable surface roughness produces micron-sized flower-shaped silver powder with a highly regular flower-shaped structure. The average diameter of the flower-shaped structure is approximately 1.5-2.5 μm, and the surface of the flower-shaped silver powder is stacked with many plate-like units, the thickness of which is approximately 150-500 nm.

[0013] The present invention also provides a flower ball silver powder obtained according to the aforementioned preparation method.

[0014] Compared with existing technologies, the present invention achieves considerable technological advancement and practicality, and has broad application value, possessing at least the following advantages: (1) The present invention features a simple process, convenient operation, mild conditions, green raw materials, short preparation process, and short preparation time, making it fast and efficient. The prepared silver powder has a highly regular flower-shaped structure with an average diameter of about 1.5-2.5 μm. The silver powder particles have a rough surface, obvious three-dimensional structural features, no obvious agglomeration or structural defects, good dispersibility, uniform particle size distribution, large specific surface area, and high purity and crystallinity. The surface of the silver powder has many plate-like units stacked on it, with a thickness of about 150-500 nm.

[0015] (2) The entire preparation process of this invention involves only the preparation steps of the precursor solution, the preparation steps of the bio-based surfactant solution, the preparation steps of the reducing agent solution, the liquid-phase reduction step after mixing, and the separation and purification steps of the reaction product. This invention provides a simple and reliable route for the preparation of flower-shaped silver powder with a regular structure. Dodecyl glucoside, as a surfactant, can regulate the morphology and structure of the product and improve its dispersibility. By controlling the concentration of the reactants and the stirring speed, flower-shaped silver powder with uniform particle size and different surface roughness can be effectively synthesized. Attached Figure Description

[0016] Figure 1 This is a 5000x magnified SEM image of the flower ball silver powder prepared in Example 1.

[0017] Figure 2 This is a 10,000x magnified SEM image of the flower ball silver powder prepared in Example 1.

[0018] Figure 3 The image shows the XRD pattern of the flower ball silver powder prepared in Example 1.

[0019] Figure 4 This is a 5000x magnified SEM image of the flower ball silver powder prepared in Example 2.

[0020] Figure 5 This is a 5000x magnified SEM image of the flower ball silver powder prepared in Example 3.

[0021] Figure 6 This is a 5000x magnified SEM image of the flower ball silver powder prepared in Example 4.

[0022] Figure 7 This is a 5000x magnified SEM image of the flower ball silver powder prepared in Example 5.

[0023] Figure 8 This is a 5000x magnified SEM image of the flower ball silver powder prepared in Example 6. Detailed Implementation

[0024] 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, 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.

[0025] The present invention will be described in detail below with reference to specific embodiments. Unless otherwise specified, all conditions in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Raw materials and reagents whose manufacturers are not specified are all commercially available products.

[0026] Example 1: 1) Weigh a certain amount of silver nitrate and add it to 200 mL of deionized water. Stir until completely dissolved to prepare a 75 mmol / L silver nitrate aqueous solution for later use. 2) Weigh a certain amount of dodecyl glucoside and add it to 200 mL of deionized water. Stir until completely dissolved to prepare a 100 mmol / L dodecyl glucoside aqueous solution for later use. 3) Weigh a certain amount of ascorbic acid and add it to 100 mL of deionized water. Stir until completely dissolved to prepare an ascorbic acid aqueous solution with a concentration of 400 mmol / L for later use. 4) Add the silver nitrate aqueous solution prepared in step 1) to a 1 L round-bottom flask. While stirring at 400 r / min, quickly add the dodecyl glucoside aqueous solution prepared in step 2) to the round-bottom flask and stir for 5.0 min to obtain a mixed solution. 5) Quickly add the ascorbic acid aqueous solution prepared in step 3) to the mixed solution obtained in step 4), and stir the mixture at 400 r / min for 1.0 h. 6) The mixture after the reaction in step 5) is subjected to solid-liquid separation. The precipitate is washed four times by centrifugation with deionized water and then dried under vacuum at 40°C for 24 hours to obtain flower ball silver powder.

[0027] Figure 1 and Figure 2 These are SEM images of the flower-shaped silver powder prepared in this embodiment at different magnifications. It can be seen that the obtained silver powder particles have a highly regular flower-shaped structure, with an average diameter of approximately 1.8 μm. The silver powder particles show no obvious agglomeration or structural defects and exhibit good dispersibility. Close observation reveals that many lamellar units are stacked on the surface of the flower-shaped silver powder, ultimately assembling into flower-shaped silver powder particles. The thickness of these lamellar units is approximately 150-200 nm.

[0028] Figure 3 The XRD pattern of the flower ball silver powder prepared in this embodiment shows that the strong diffraction peaks indicate that the product has high crystallinity and a face-centered cubic structure, mainly exposing the (111) crystal plane. No other impurity peaks appear, which proves that the product has high purity.

[0029] Example 2: 1) Weigh a certain amount of silver nitrate and add it to 200 mL of deionized water. Stir until completely dissolved to prepare a 100 mmol / L silver nitrate aqueous solution for later use. 2) Weigh a certain amount of dodecyl glucoside and add it to 200 mL of deionized water. Stir until completely dissolved to prepare a 150 mmol / L dodecyl glucoside aqueous solution for later use. 3) Weigh a certain amount of ascorbic acid and add it to 100 mL of deionized water. Stir until completely dissolved to prepare an ascorbic acid aqueous solution with a concentration of 400 mmol / L for later use. 4) Add the silver nitrate aqueous solution prepared in step 1) to a 1 L round-bottom flask. While stirring at 400 r / min, quickly add the dodecyl glucoside aqueous solution prepared in step 2) to the round-bottom flask and stir for 5.0 min to obtain a mixed solution. 5) Quickly add the ascorbic acid aqueous solution prepared in step 3) to the mixed solution obtained in step 4), and stir the mixture at 400 r / min for 1.0 h. 6) The mixture after the reaction in step 5) was subjected to solid-liquid separation. The precipitate was washed four times by centrifugation with deionized water and then dried under vacuum at 50°C for 20 h to obtain flower ball silver powder.

[0030] Figure 4This is a SEM image of the flower-shaped silver powder prepared in this embodiment. It can be seen that the obtained silver powder particles have a highly regular flower-shaped structure, with an average diameter of approximately 2.0 μm. The surface of the silver powder particles has a regular three-dimensional flower-shaped structure, slightly reduced roughness, no obvious agglomeration or structural defects, and good dispersibility. The thickness of the stacked lamellar units on the silver powder surface is approximately 150-200 nm.

[0031] Example 3: 1) Weigh a certain amount of silver nitrate and add it to 200 mL of deionized water. Stir until completely dissolved to prepare a 50 mmol / L silver nitrate aqueous solution for later use. 2) Weigh a certain amount of dodecyl glucoside and add it to 200 mL of deionized water. Stir until completely dissolved to prepare a 200 mmol / L dodecyl glucoside aqueous solution for later use. 3) Weigh a certain amount of ascorbic acid and add it to 100 mL of deionized water. Stir until completely dissolved to prepare an ascorbic acid aqueous solution with a concentration of 400 mmol / L for later use. 4) Add the silver nitrate aqueous solution prepared in step 1) to a 1 L round-bottom flask. While stirring at 400 r / min, quickly add the dodecyl glucoside aqueous solution prepared in step 2) to the round-bottom flask and stir for 5.0 min to obtain a mixed solution. 5) Quickly add the ascorbic acid aqueous solution prepared in step 3) to the mixed solution obtained in step 4), and stir the mixture at 400 r / min for 1.0 h. 6) The mixture after the reaction in step 5) was subjected to solid-liquid separation. The precipitate was washed four times by centrifugation with deionized water and then dried under vacuum at 60 °C for 10 h to obtain flower ball silver powder.

[0032] Figure 5 This is a SEM image of the flower-shaped silver powder prepared in this embodiment. It can be seen that the average diameter of the flower-shaped silver powder is about 2.5 μm. The three-dimensional structure of the flower-shaped structure on the surface of the silver powder is weakened, the roughness is slightly reduced, some silver spheres are smooth, there is no obvious agglomeration, and the dispersibility is good. The thickness of the plate-like units stacked on the surface of the silver powder is about 150-200 nm.

[0033] Example 4: 1) Weigh a certain amount of silver nitrate and add it to 200 mL of deionized water. Stir until completely dissolved to prepare a 50 mmol / L silver nitrate aqueous solution for later use. 2) Weigh a certain amount of dodecyl glucoside and add it to 200 mL of deionized water. Stir until completely dissolved to prepare a 250 mmol / L dodecyl glucoside aqueous solution for later use. 3) Weigh a certain amount of ascorbic acid and add it to 100 mL of deionized water. Stir until completely dissolved to prepare an ascorbic acid aqueous solution with a concentration of 400 mmol / L for later use. 4) Add the silver nitrate aqueous solution prepared in step 1) to a 1 L round-bottom flask. While stirring at 400 r / min, quickly add the dodecyl glucoside aqueous solution prepared in step 2) to the round-bottom flask and stir for 5.0 min to obtain a mixed solution. 5) Quickly add the ascorbic acid aqueous solution prepared in step 3) to the mixed solution obtained in step 4), and stir the mixture at 400 r / min for 1.0 h. 6) The mixture after the reaction in step 5) was subjected to solid-liquid separation. The precipitate was washed four times by centrifugation with deionized water and then dried under vacuum at 55°C for 15 h to obtain flower ball silver powder.

[0034] Figure 6 This is a SEM image of the flower-shaped silver powder prepared in this embodiment. It can be seen that the average diameter of the flower-shaped silver powder is approximately 1.5 μm, the three-dimensional structure of the silver powder surface is obvious, the roughness is more pronounced, and the spherical morphology of the flower-shaped powder is not... Figure 5 The resulting flower heads are rounded, and the silver powder particles show no obvious agglomeration, exhibiting good dispersion. The stacked lamellar units on the surface of the silver powder are more prominent, with a thickness of approximately 200-300 nm.

[0035] Example 5: 1) Weigh a certain amount of silver nitrate and add it to 200 mL of deionized water. Stir until completely dissolved to prepare a 50 mmol / L silver nitrate aqueous solution for later use. 2) Weigh a certain amount of dodecyl glucoside and add it to 200 mL of deionized water. Stir until completely dissolved to prepare a 250 mmol / L dodecyl glucoside aqueous solution for later use. 3) Weigh a certain amount of ascorbic acid and add it to 100 mL of deionized water. Stir until completely dissolved to prepare an 800 mmol / L ascorbic acid aqueous solution for later use. 4) Add the silver nitrate aqueous solution prepared in step 1) to a 1 L round-bottom flask. While stirring at 400 r / min, quickly add the dodecyl glucoside aqueous solution prepared in step 2) to the round-bottom flask and stir for 5.0 min to obtain a mixed solution. 5) Quickly add the ascorbic acid aqueous solution prepared in step 3) to the mixed solution obtained in step 4), and stir the mixture at 400 r / min for 1.0 h. 6) The mixture after the reaction in step 5) was subjected to solid-liquid separation. The precipitate was washed four times by centrifugation with deionized water and then dried under vacuum at 45°C for 18 h to obtain silver powder.

[0036] Figure 7 This is a SEM image of the silver powder prepared in this embodiment. Compared with Example 4, with the amounts of silver nitrate and dodecyl glucoside remaining unchanged, increasing the concentration and amount of ascorbic acid resulted in most of the silver powder exhibiting a nearly flower-like morphology, with a more open surface structure and more pronounced roughness. The flower-like structure is assembled from many lamellar units, and the thickness of the lamellar units increased to approximately 300-500 nm. This indicates that the ratio of silver nitrate to ascorbic acid has a significant impact on the morphology of the silver powder.

[0037] Example 6: 1) Weigh a certain amount of silver nitrate and add it to 200 mL of deionized water. Stir until completely dissolved to prepare a 50 mmol / L silver nitrate aqueous solution for later use. 2) Weigh a certain amount of dodecyl glucoside and add it to 200 mL of deionized water. Stir until completely dissolved to prepare a 250 mmol / L dodecyl glucoside aqueous solution for later use. 3) Weigh a certain amount of ascorbic acid and add it to 100 mL of deionized water. Stir until completely dissolved to prepare an 800 mmol / L ascorbic acid aqueous solution for later use. 4) Add the silver nitrate aqueous solution prepared in step 1) to a 1 L round-bottom flask. While stirring at 800 r / min, quickly add the dodecyl glucoside solution prepared in step 2) to the round-bottom flask and stir for 5.0 min to obtain a mixed solution. 5) Quickly add the ascorbic acid aqueous solution prepared in step 3) to the mixed solution obtained in step 4), and stir at 800 r / min for 1.0 h; 6) The mixture after the reaction in step 5) was subjected to solid-liquid separation. The precipitate was washed four times by centrifugation with deionized water and then dried under vacuum at 55°C for 15 h to obtain silver powder.

[0038] Figure 8 This is an SEM image of the silver powder prepared in this embodiment. Compared with Example 5, after the stirring rate was increased, most of the silver powder showed a clumping structure without obvious flower ball morphology. The clumping structure was assembled by stacking many sheet-like units, and the product showed obvious agglomeration and poor dispersibility.

[0039] The above examples illustrate that by adjusting the reactant concentration and stirring speed, flower-shaped silver powder with adjustable surface roughness can be synthesized.

[0040] 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 micron-sized flower-shaped silver powder with adjustable surface roughness, characterized in that, Includes the following steps: (1) Weigh a certain amount of silver nitrate and add it to deionized water. Stir until completely dissolved to prepare a silver nitrate aqueous solution with a concentration of 50-100 mmol / L for later use. (2) Weigh a certain amount of dodecyl glucoside and add it to deionized water. Stir until completely dissolved to prepare an aqueous solution of dodecyl glucoside with a concentration of 100-300 mmol / L for later use. (3) Weigh a certain amount of ascorbic acid and add it to deionized water. Stir until completely dissolved to prepare an ascorbic acid aqueous solution with a concentration of 200-600 mmol / L for later use. (4) Add the silver nitrate aqueous solution prepared in step (1) to the reaction vessel. Under stirring conditions, quickly add the dodecyl glucoside aqueous solution prepared in step (2) to the reaction vessel and stir for 5-15 min to obtain a mixed solution. Quickly add the ascorbic acid aqueous solution prepared in step (3) to the obtained mixed solution and stir for 1-2 h. (5) After stirring and reacting in step (4), the mixture is separated into solid and liquid phases. The precipitate is washed with deionized water by centrifugation 3-5 times and then vacuum dried to obtain micron-sized flower ball silver powder with adjustable surface roughness.

2. The method for preparing micron-sized flower-shaped silver powder with adjustable surface roughness as described in claim 1, characterized in that, In step (4), the molar ratio of silver nitrate to dodecyl glucoside is 1:(1-5).

3. The method for preparing micron-sized flower-shaped silver powder with adjustable surface roughness as described in claim 1, characterized in that, In step (4), the molar ratio of silver nitrate to ascorbic acid is 1:(2-4).

4. The method for preparing micron-sized flower-shaped silver powder with adjustable surface roughness as described in claim 1, characterized in that, The volume ratio of the silver nitrate aqueous solution, dodecyl glucoside aqueous solution, and ascorbic acid aqueous solution in step (4) is 2:2:

1.

5. The method for preparing micron-sized flower-shaped silver powder with adjustable surface roughness as described in claim 1, characterized in that, The stirring speed in step (4) is 300-600 r / min.

6. The method for preparing micron-sized flower-shaped silver powder with adjustable surface roughness as described in claim 1, characterized in that, Step (5) Vacuum drying temperature is 40-60℃, time is 10-24 h.

7. The method for preparing micron-sized flower-shaped silver powder with adjustable surface roughness as described in claim 1, characterized in that, The obtained micron-sized flower-shaped silver powder has a highly regular flower-shaped structure with an average diameter of 1.5-2.5 μm. The surface of the flower-shaped powder is stacked with many plate-like units with a thickness of 150-500 nm.

8. Flowerball silver powder obtained by any of the preparation methods described in claims 1-6.

Images