Method for synthesizing high-purity silver nano-spiral at room temperature and application of high-purity silver nano-spiral

Abstract

The invention discloses a method for synthesizing high-purity silver nano-spirals at room temperature and application of the high-purity silver nano-spirals at room temperature, and the method comprises the following steps: A1, preparing a soft template aqueous solution, adding a silicon-based material which is 1-50000 times of the mass of the soft template, fully mixing, and standing; a2, adding silver salt which is 1-500 times of the mass of the soft template, oscillating and fully mixing; a3, adding a proper amount of a reducing agent, uniformly mixing reactants, and standing and reacting the reaction liquid at room temperature for 24-48 hours; and after the reaction is finished, taking out a solid substance, washing with deionized water for multiple times to remove redundant soft template and unreacted silver salt and reducing agent, filtering and separating the silicon-based material and the product silver nano spiral, and drying the product in a drying box. According to the method, synthesis of the silver nano spiral at room temperature can be achieved, and the yield exceeds 95%. The obtained spiral structure has highly uniform screw pitch, and the length can exceed 150 [mu] m.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials technology, and in particular to a method for synthesizing high-purity ultralong silver nanospirals at room temperature and its application. Background Technology

[0002] Silver, as the metal with the best electrical conductivity, has numerous applications in nanomaterials in electronics, catalysis, material analysis, and chiral optics. For example, silver nanohelices not only inherit the conductivity and flexibility of silver nanowires (one-dimensional), but also possess unique properties characteristic of three-dimensional helical structures, such as circular dichroism, tunable chiral optical response, and high elasticity, thus demonstrating broader application potential. However, the controllable synthesis of metal nanohelices still faces significant challenges, primarily due to the difficulty in achieving continuous and controllable asymmetric growth at the nanoscale. Currently, common strategies for synthesizing silver nanohelices, such as template methods (using helical templates to guide silver deposition) and tilt-angle deposition methods (relying on equipment such as magnetron sputtering or electron beam evaporation), typically suffer from complex processes, high costs, low yields, poor helical structure uniformity (such as uneven pitch), and limited length, all of which hinder in-depth research and application development of this material. Summary of the Invention

[0003] This invention addresses the shortcomings of existing technologies by providing a method for synthesizing high-purity ultralong silver nanospirals at room temperature and its applications.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A method for synthesizing high-purity silver nanospirals at room temperature includes the following steps: Prepare an appropriate amount of soft template aqueous solution, with the amount of soft template accounting for 0.0001%-10% of the water mass. Then add 1-50,000 times the mass of the soft template silicon-based material. After thorough mixing and standing, the two will form a stable hydrogen bond network. At this time, the soft template molecular chains are twisted and attached to the surface of the silicon-based material. Add 1-500 times the mass of silver salt to the soft template, shake to mix thoroughly, and allow silver ions to adsorb onto the molecular chain of the soft template to form a precursor. At this time, there is a concentration difference between the side close to the silicon-based material and the side far from the silicon-based material, which creates an asymmetric environment and provides conditions for the generation of stress in the precursor. Add an appropriate amount of reducing agent, mix the reactants evenly, and let the reaction solution stand at room temperature for 24-48 hours. After the reaction is complete, separate the solid material, rinse it with deionized water several times to remove excess soft template, unreacted silver salt and reducing agent, and filter to separate the silicon-based material and the product silver nanospiral.

[0005] The method for synthesizing high-purity silver nanospirals at room temperature uses one or more water-soluble silver salts, selected from silver nitrate, silver perchlorate, silver fluoroborate, silver acetylacetone, or silver acetylacetone sulfonate.

[0006] The method for synthesizing high-purity silver nanospirals at room temperature involves using a soft template at a mass percentage of 0.0001%-1% of water, followed by the addition of silicon-based material at a mass of 1-200 times that of the soft template.

[0007] The method for synthesizing high-purity silver nanospirals at room temperature involves adding 1-150 times the mass of silver salt as a soft template.

[0008] The method for synthesizing high-purity silver nanospirals at room temperature uses a soft template that is one or more polymers containing hydrophilic groups, selected from polyacrylic acid, polyallylamine hydrochloride, sodium polyacrylate, polymethacrylic acid, polymaleic anhydride, polyvinyl alcohol, or polyethylene glycol.

[0009] The method for synthesizing high-purity silver nanospirals at room temperature uses silicon-based materials that are solids containing silicon, including elemental silicon, silicon oxides, and other compounds containing silicon.

[0010] The method for synthesizing high-purity silver nanospirals at room temperature uses silicon-based materials selected from silica powder, glass, ceramics, silica gel, and natural stone, with the natural stone selected from quartz, granite, or sand.

[0011] Silver nanospirals were prepared according to any of the methods described.

[0012] The application of the silver nanospirals in the fabrication of strain sensing electrodes.

[0013] This invention develops a simple and efficient one-step method for synthesizing silver nanohelices in an aqueous phase at room temperature. The method requires no complex equipment or chiral templates; it only requires a reaction in an aqueous solution at room temperature to achieve scalable preparation of silver nanohelices. The method is simple to operate, highly reproducible, and has low instrument requirements. Experimental results show that this method can synthesize silver nanohelices at room temperature with a yield exceeding 95%. The obtained helical structures have highly uniform pitch and lengths exceeding 150 μm, which is the longest silver nanohelices reported in the literature to date. Furthermore, the product obtained by this method is a mixture of single-stranded and double-stranded helices, with the double-stranded helices also exhibiting uniform pitch. Compared to silver nanowires, the prepared silver nanohelices exhibit greater flexibility, capable of bending 180° without breaking. Attached Figure Description

[0014] Figure 1 The image shows a SEM image of silver nanospirals prepared in Example 1 (particle size 30 nm).

[0015] Figure 2 The X-ray diffraction pattern of the silver nanospirals prepared in Example 1 is shown.

[0016] Figure 3 The image shows a SEM image of the double-stranded silver nanospiral prepared in Example 1.

[0017] Figure 4 SEM images of silver nanospirals prepared in Example 1 at different bending angles.

[0018] Figure 5 The images show different bending angles (TEM) of the silver nanospirals prepared in Example 1.

[0019] Figure 6 The image shows a SEM image of silver nanospirals prepared in Example 1 (particle size 3 micrometers).

[0020] Figure 7 This is a SEM image of silver nanospirals prepared in Example 2 (particle size 30 nm).

[0021] Figure 8 This is a SEM image of silver nanospirals prepared in Example 2 (particle size 60 μm).

[0022] Figure 9 This is a SEM image of silver nanospirals prepared in Example 3 (particle size 30 nm).

[0023] Figure 10 This is a SEM image of silver nanospirals prepared in Example 4 (particle size 30 nm).

[0024] Figure 11 This is a SEM image of silver nanospirals prepared in Example 5 (particle size 30 nm).

[0025] Figure 12 The diagram shows the strain electrical signal transmission performance of the silver nano-spiral electrode. Detailed Implementation

[0026] The present invention will be described in detail below with reference to specific embodiments.

[0027] Example 1: Preparation of silver nanospirals: Polyacrylic acid and silica powder (30 nm) were added sequentially to 100 mL of deionized water. The amount of polyacrylic acid was 0.0012% of the mass of deionized water, and the amount of silica powder was 0.5% of the mass of deionized water. The mixture was stirred vigorously at room temperature to ensure thorough mixing, and then allowed to stand for 10 minutes.

[0028] Then add 0.044 g of silver nitrate and 0.022 g of ascorbic acid in sequence and let them dissolve.

[0029] After the reactants were thoroughly mixed, the reaction solution was allowed to stand at room temperature for 48 hours. After the reaction was complete, the solid material was removed and repeatedly rinsed with deionized water to remove excess polyacrylic acid, unreacted silver nitrate, and ascorbic acid. Silica and silver nanospirals were separated by centrifugation and filtration, and then dried in a drying oven. The resulting silver nanospiral product was a mixture of single-stranded and double-stranded helices, such as... Figure 1 (Single-strand spiral) and Figure 3 (Double helix) is a helical structure found in the same batch of products. Figure 4 and Figure 5 The single-strand helix was bent at different angles, and no breakage occurred at any of these angles, demonstrating excellent flexibility. X-ray diffraction results are as follows... Figure 2 The peak position corresponds to cubic silver (PDF:04-0783), proving that the spiral is elemental silver with a purity ≥95%.

[0030] The particle size of silica powder does not affect the formation of silver nanospirals, but only the yield. In fact, the larger the particle size of the silica powder, the lower the yield of silver nanospirals. Figure 6 Silver nanospirals prepared using silica powder with a particle size of 3 μm showed reduced yield and a large number of silver nanowire impurities.

[0031] Example 2: Preparation of silver nanospirals: Sodium polyacrylate and glass powder (30 nm) were added sequentially to 100 mL of deionized water. The amount of sodium polyacrylate was 0.0056% of the mass of deionized water, and the amount of glass powder was 0.7% of the mass of deionized water. The mixture was stirred vigorously at room temperature to ensure thorough mixing, and then allowed to stand for 10 minutes.

[0032] Then add 0.069 g of silver acetylacetone and 0.03 g of ascorbic acid in sequence and let them dissolve.

[0033] After the reactants were mixed thoroughly, the reaction solution was allowed to stand at room temperature for 48 hours. After the reaction was complete, the solid material was removed and repeatedly washed with deionized water to remove excess sodium polyacrylate, unreacted silver acetylacetone, and ascorbic acid. The glass powder and silver nanospirals were separated by centrifugation and filtration, and then dried in a drying oven. The obtained silver nanospirals are shown below. Figure 7 .

[0034] The particle size of the glass powder does not affect the formation of silver nanospirals, but only the yield. In fact, the larger the particle size of the glass powder, the lower the yield of silver nanospirals. Figure 8 Silver nanospirals were prepared from glass powder with an average particle size of 60 μm. The yield was reduced and a large number of silver nanowire impurities appeared. The purity was ≥86%.

[0035] Example 3: Preparation of silver nanospirals: In 100 mL of deionized water, polyethylene glycol and ceramic powder (30 nm) were added sequentially. The amount of polyethylene glycol was 0.0031% of the mass of deionized water, and the amount of ceramic powder was 0.5% of the mass of deionized water. The mixture was stirred vigorously at room temperature to ensure thorough mixing, and then allowed to stand for 10 minutes.

[0036] Then add 0.052 g of silver perchlorate and 0.01 g of hydrazine hydrate in sequence and let them dissolve.

[0037] After the reactants were mixed thoroughly, the reaction solution was allowed to stand at room temperature for 48 hours. After the reaction was complete, the solid material was removed and repeatedly rinsed with deionized water to remove excess polyethylene glycol, unreacted silver perchlorate, and hydrazine hydrate. The ceramic powder and silver nanospirals were separated by centrifugation and filtration, and then dried in a drying oven. The obtained silver nanospirals are shown below. Figure 9 .

[0038] The particle size of the ceramic powder does not affect the formation of silver nanospirals, but only the yield. In fact, the larger the particle size of the ceramic powder, the lower the yield of silver nanospirals, with a purity ≥80%.

[0039] Example 4: Preparation of silver nanospirals: In 100 mL of deionized water, polymethyl methacrylate and silica gel powder (30 nm) were added sequentially. The amount of polymethyl methacrylate was 0.0024% of the mass of deionized water, and the amount of silica gel powder was 0.6% of the mass of deionized water. The mixture was stirred vigorously at room temperature to ensure thorough mixing, and then allowed to stand for 10 minutes.

[0040] Then add 0.1122 g of silver acetylacetone sulfonate and 0.034 g of sodium ascorbate in sequence and let them dissolve.

[0041] After the reactants were mixed thoroughly, the reaction solution was allowed to stand at room temperature for 48 hours. After the reaction was complete, the solid material was removed and repeatedly washed with deionized water to remove excess polymethacrylic acid, unreacted silver acetylacetone sulfonate, and sodium ascorbate. The silica gel powder and silver nanospirals were separated by centrifugation and filtration, and then dried in a drying oven. The obtained silver nanospirals are shown below. Figure 10 .

[0042] The particle size of silica powder does not affect the formation of silver nanospirals, but only the yield. In fact, the larger the particle size of the silica powder, the lower the yield of silver nanospirals, with a purity ≥88%.

[0043] Example 5: Preparation of silver nanospirals: Add polyvinyl alcohol and polyacrylic acid to 100 mL of deionized water, then add silicon elemental powder (30 nm). The amount of polyvinyl alcohol is 0.0016% of the mass of deionized water, the amount of polyacrylic acid is 0.0022% of the mass of deionized water, and the amount of silicon elemental powder is 0.3% of the mass of deionized water. Stir vigorously at room temperature to mix thoroughly, and then let stand for 10 minutes.

[0044] Then add 0.0315 g of silver fluoroborate and 0.015 g of sodium borohydride in sequence and let them dissolve.

[0045] After the reactants were mixed thoroughly, the reaction solution was allowed to stand at room temperature for 48 hours. After the reaction was complete, the solid material was removed and repeatedly rinsed with deionized water to remove excess polyvinyl alcohol, polyacrylic acid, and unreacted silver fluoroborate and sodium borohydride. The silicon powder and silver nanospirals were separated by centrifugation and filtration, and then dried in a drying oven. The obtained silver nanospirals are shown below. Figure 11 .

[0046] Based on the comparison of SEM and TEM of the products, Example 1 is the optimal solution, which yields silver nanospirals with the fewest impurities, uniform pitch, and good flexibility.

[0047] The particle size of silicon powder does not affect the formation of silver nanospirals, but only the yield. In fact, the larger the particle size of silicon powder, the lower the yield of silver nanospirals, with a purity ≥82%.

[0048] Example 6: Application of silver nanohelices in strain sensors: Weigh 1g of the silver nanospiral prepared in Example 1, disperse it in 25 mL of ethanol, disperse it evenly in an ultrasonic machine, coat it on a polydimethylsiloxane film, and dry the excess solution in an oven at 150°C to allow the silver nanospiral to adhere to the polydimethylsiloxane film, thus forming a strain sensing electrode.

[0049] Preparation of the control sample: 0.0125 mmol silver nitrate and 0.0625 mmol ascorbic acid were added to 50 mL of polyacrylic acid aqueous solution (polyacrylic acid accounted for 0.06‰ of the water mass), and the reaction was carried out at room temperature for 48 hours to obtain linear one-dimensional silver nanomaterials (Ag NBs). The strain sensing electrode was prepared by the same method as above.

[0050] like Figure 12 Compared with the maximum strain electrical signal transmission (8%) of the control linear one-dimensional silver nanomaterials (Ag NBs), the silver nanospiral electrode exhibits better strain electrical signal transmission (32%). This demonstrates that the silver nanospirals prepared in Example 1 still maintain good conductivity under large deformation.

[0051] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for synthesizing high purity silver nanohelixes at room temperature, characterized in that, The method comprises the following steps: A1, preparing a soft template aqueous solution, the mass percentage of the soft template in water is 0.0001%-10%, then adding a silicon-based material with a mass of 1-50000 times of the soft template, mixing thoroughly, and then standing; A2, adding a silver salt with a mass of 1-500 times of the soft template, and mixing thoroughly by oscillation; A3, adding an appropriate amount of a reducing agent, mixing the reactants uniformly, and then standing the reaction solution at room temperature for 24-48 hours; after the reaction is completed, separating the solid substance, washing with deionized water for multiple times to remove the excess soft template, unreacted silver salt, and reducing agent, and then filtering and separating the silicon-based material and the product silver nanohelix, and drying the product in a drying oven.

2. The method of claim 1, wherein the silver nanohelixes are synthesized at room temperature. The silver salt is one or more of water-soluble silver salts selected from silver nitrate, silver perchlorate, silver fluoroborate, silver acetylacetone, or silver acetylacetone sulfonate.

3. The method of claim 1, wherein the silver nanohelixes are synthesized at room temperature. The mass percentage of the soft template in water is 0.0001%-1%, then adding a silicon-based material with a mass of 1-200 times of the soft template.

4. The method of claim 1, wherein the silver nanohelixes are synthesized at room temperature with high purity, characterized by, Adding a silver salt with a mass of 1-150 times of the soft template.

5. The method of claim 1, wherein the silver nanohelixes are synthesized at room temperature. The soft template is one or more of polymers containing a hydrophilic group selected from polyacrylic acid, polyallylamine hydrochloride, polyacrylic acid sodium, polymethylacrylic acid, polymaleic anhydride, polyvinyl alcohol, or polyethylene glycol.

6. The method of claim 1, wherein the silver nanohelixes are synthesized at room temperature. The silicon-based material is a solid containing silicon elements, including a component containing silicon single element or silicon oxide, and other compounds containing silicon elements.

7. The method of claim 1, wherein the silver nanohelixes are synthesized at room temperature. The silicon-based material is selected from silica powder, glass, ceramic, silica gel, and natural stone, and the natural stone is selected from quartz stone, granite, or sandstone.

8. The silver nanohelix obtained by the method according to any one of claims 1-7.

9. The silver nanohelix according to claim 8 for use in the preparation of a strain sensing electrode.

Images