Preparation method for flexible electronic one-dimensional micron silver rod
By controlling the concentration and temperature of silver nitrate in HNO3-ethanol solution and combining PVP regulation, one-dimensional Ag microrods with controllable size are prepared, which solves the problems of complex operation and high energy consumption in the prior art, and achieves the preparation of micron silverrods with high stability and high yield, which is suitable for flexible electronic devices.
Patent Information
- Application Number
- CN202510419546.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-03
- Publication Date
- 2025-07-11
AI Technical Summary
The existing one-dimensional micron silver rod preparation method is complex in operation, high in energy consumption, and high in cost, making it difficult to meet the needs of flexible electronic materials.
Using the HNO3-ethanol solution system, by controlling the concentration gradient of silver nitrate and reaction temperature, combining PVP as a reducing agent and morphological regulator, a one-dimensional Ag microrod with controllable size was prepared to avoid secondary processing and use the environmentally friendly solvent ethanol.
It realizes the simple preparation of micron silver rods, has high stability and high yield, is suitable for key functional materials for flexible electronic devices, and has a nano-silver composite structure with excellent conductivity.
Smart Images
Figure CN120286722A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of electronic materials, and particularly relates to a preparation method for flexible electronic one-dimensional micron silver rods. Background Art
[0002] Flexible electronic materials are a class of emerging materials that combine flexibility, stretchability, and electrical functionality. Their core goal is to provide a suitable hardware foundation for wearable devices, electronic skin, flexible displays, and implantable medical devices. The material systems in this field cover intrinsically flexible materials (such as conductive polymer PEDOT:PSS, elastomer PDMS) and structurally flexible design materials (such as metal nanowires / micron rods, graphene wrinkled films, liquid metal circuits). Through molecular engineering, micro-nano structure regulation, or hetero-composite strategies, the mechanical properties (tensile rate > 50%, bending > 10^4 times) and electrical properties (conductivity > 10 3 S / cm) are synergistically optimized. Current research focuses on multifunctional integration (self-healing, environmental response, light transmittance), green manufacturing processes (printed electronics, low-temperature processing), and bio-electronic interface optimization. The challenges lie in the stability decay during long-term use, the compatibility of multi-material interfaces, and the consistency of large-scale production. The future trend will be towards ultra-thin heterogeneous integration, bionic intelligent materials, and integrated flexible systems, promoting disruptive innovations in fields such as human-computer interaction and intelligent healthcare. And anisotropic noble metal micro-nano structures are currently very attractive materials due to their unique physical and chemical properties.
[0003] As a metal material with a unique one-dimensional structure, micron rod-shaped silver exhibits broad application prospects in multiple fields due to its excellent physical and chemical properties. In the field of electronic devices, its high aspect ratio and anisotropic characteristics make it an ideal choice for flexible conductive materials. A highly conductive network can be constructed through directional arrangement and applied to wearable devices, flexible touchscreens, and printed electronic circuits. Its conductivity is superior to that of traditional spherical silver powder and less amount is used. In the field of catalysis, the one-dimensional structure exposes more active crystal planes. Combining with the surface plasmon resonance effect, it shows higher catalytic efficiency than nanoparticles in reactions such as visible light catalytic degradation of organic pollutants and carbon dioxide reduction, and the micron-scale size is more easily recycled and reused. In the field of energy, as a conductive additive for electrode materials of lithium-ion batteries and supercapacitors, its directional arrangement structure can significantly improve the electrode conductivity and structural stability, while in photovoltaic devices, the light absorption is enhanced through the surface plasmon effect.
[0004] Compared with other forms of silver materials, micro-rod-shaped silver has significant advantages: its one-dimensional structure endows it with excellent mechanical strength and flexibility, and its electrical and optical properties can be precisely adjusted by controlling the aspect ratio; the micro-scale size not only maintains the high specific surface area characteristics but also avoids the problems of easy aggregation and difficult recovery of nanomaterials; there is a large space for surface functionalization modification, and strong interfacial bonding can be formed with matrices such as polymers and ceramics. It is worth noting that the material has outstanding advantages in the balance between biocompatibility and antibacterial properties. By controlling the size, cytotoxicity can be reduced while maintaining antibacterial activity, which is crucial for the development of new medical materials; with the development of emerging fields such as flexible electronics and green catalysis, the application potential of micro-rod-shaped silver in intelligent response materials, efficient catalytic systems, etc. is being continuously explored, and its multi-scale structure regulation and composite technology will become the focus of future research.
[0005] Currently, the existing preparation methods of one-dimensional micro silver rods are generally complex in operation. Some methods require the prior synthesis of silver particles and then secondary processing through mechanical ball milling or template method to synthesize one-dimensional micro silver rods, which is complex in operation, high in energy consumption, and costly. Summary of the Invention
[0006] Aiming at the above-mentioned disadvantages of the prior art, the present invention provides a preparation method for one-dimensional micro silver rods that can be used in flexible electronics.
[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:
[0008] A preparation method for one-dimensional micro silver rods that can be used in flexible electronics, comprising the following steps:
[0009] (1) Drop HNO3 into an ethanol solution to obtain an HNO3-ethanol solution.
[0010] (2) Dissolve AgNO3 in an ethanol solution to obtain an AgNO3-ethanol solution.
[0011] (3) Dissolve PVP in the HNO3-ethanol solution prepared in step (1) to obtain a PVP / HNO3 ethanol solution.
[0012] (4) Drop the PVP / HNO3-ethanol solution obtained in step (3) into the AgNO3-ethanol solution prepared in step (2), and then stir and perform ultrasonic treatment.
[0013] (5) Seal the solution after ultrasonic treatment and let it stand at room temperature to obtain a precipitate, and then centrifuge, wash, and dry the precipitate to obtain micro silver rods.
[0014] As a preferred embodiment of the present invention, in the step (1), the amount of HNO3 in the HNO3-ethanol solution is 0.01 to 0.05 g / mL, and more preferably, the amount of HNO3 in the HNO3-ethanol is 0.02 to 0.05 g / mL.
[0015] The present invention needs to be carried out in an HNO3-ethanol solution environment with an HNO3-ethanol solution dosage of 0.02-0.05 g / mL to obtain one-dimensional Ag microrods with uniform size and morphology and high Ag yield; when nitric acid is not added or the concentration of added nitric acid is greater than or less than 0.01-0.05 g / mL, the material morphology will change, Ag single substance with various morphologies will be generated, and the Ag yield will also be reduced.
[0016] As a preferred embodiment of the present invention, the concentration of AgNO3 in the AgNO3-ethanol solution in step (2) is 0.02 to 0.07 g / mL.
[0017] As a preferred embodiment of the present invention, the concentration of PVP in the PVP / HNO3-ethanol solution in step (3) is 0.004-0.014 g / mL, and the degree of polymerization of PVP is K30-K90.
[0018] As a preferred embodiment of the present invention, the volume ratio of the AgNO3-ethanol solution to the PVP / HNO3-ethanol solution in step (4) is 1:1.
[0019] As a preferred embodiment of the present invention, in the step (4), the stirring time is 20 to 40 minutes, the ultrasonic treatment time is 30 to 60 minutes, and the ultrasonic treatment power is 200 to 800w.
[0020] As a preferred embodiment of the present invention, in step (5), the time of standing at room temperature is 14 to 21 days.
[0021] As a preferred embodiment of the present invention, in the step (5), the centrifugation condition is 6000-8000 rpm, and the centrifugation time is 30-50 min.
[0022] As a preferred embodiment of the present invention, in the step (5), the drying temperature is 60 to 80° C., and the drying time is 48 to 72 hours.
[0023] The one-dimensional Ag micro-rod prepared by the invention is column-like in shape, the nano silver particle diameter is in the range of 50-150nm, and the length is 3.860-5.666μm.
[0024] Compared with the prior art, the present invention has the following advantages:
[0025] (1) The micron silver rods of the present invention have controllable sizes. Based on the silver crystal nucleation-growth kinetics regulation mechanism, by controlling the concentration gradient of silver nitrate and the reaction temperature, the size of the particle diameter can be grasped, realizing precise regulation of the particle diameter of micron silver particles within the range of 1.1 - 5.8 μm, with high stability (after being placed for three months, its size and morphology hardly change). If the surface of the micron silver rods is modified with nanostructures (such as nanoparticle coatings) to enhance the interfacial bonding or catalytic performance, and is compounded with nanomaterials (such as carbon nanotubes, graphene) to form a multi-scale conductive network, it can be used as a key functional material (such as conductive filler, electrode material) of flexible electronic devices, and its design, preparation and performance optimization all serve the needs of flexible electronic technology.
[0026] (2) The present invention uses PVP as a reducing agent. Under the action of a nitric acid acidified environment, the addition of nitric acid reduces the pH of the solution, protonates the pyrrolidone group in the PVP molecule, and the positively charged PVP is more inclined to adsorb on the {100} crystal plane of the silver crystal, inhibiting the growth of these planes. During this process, the dispersion effect and reduction effect of PVP reach an equilibrium state, and the unadsorbed {111} crystal plane grows preferentially to form a rod-like structure, thus achieving the effect of forming uniform rod-like one-dimensional Ag micron rods of Ag, and there is a slight attachment of nano silver spheres on the surface of the prepared one-dimensional Ag micron rods, which is convenient for subsequent compounding with micro-nano silver particles, with good monodispersity and relatively uniform particle size distribution.
[0027] (3) The present invention follows the principle of green ecological preparation; the preparation of micron rods is carried out in a state where ethanol is used as a solvent. Compared with organic solvents such as benzene, acetone, and isopropanol used in other technologies, ethanol has the advantages of high volatility and being harmless to the human body.
[0028] (4) The steps of the present invention are simple; compared with other preparation processes, the preparation process of the present invention is simple, the generated one-dimensional micron silver rods do not require secondary processing, and the energy consumption is less. Description of the Drawings
[0029] Figure 1 Scanning electron microscope image of the one-dimensional Ag micron rods prepared in Example 1.
[0030] Figure 2 Scanning electron microscope image of the one-dimensional Ag micron rods prepared in Example 2.
[0031] Figure 3 Scanning electron microscope image of the one-dimensional Ag micron rods prepared in Example 3.
[0032] Figure 4 Scanning electron microscope image of the silver particles prepared in Comparative Example 1.
[0033] Figure 5Scanning electron microscope image of the silver particles prepared in Comparative Example 2.
[0034] Figure 6 Scanning electron microscope image of the silver particles prepared in Comparative Example 3.
[0035] Figure 7 Scanning electron microscope image of the silver particles prepared in Comparative Example 4.
[0036] Figure 8 Scanning electron microscope image of the silver particles prepared in Comparative Example 6. Detailed implementation manners
[0037] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the content described.
[0038] Example 1
[0039] A method for preparing one-dimensional Ag micro-rods includes the following steps:
[0040] (1) 0.1 g of nitric acid is dropped into 10 mL of ethanol solution to obtain a HNO3-ethanol solution.
[0041] (2) 0.2 g of AgNO3 is dissolved in 10 mL of ethanol to obtain an AgNO3-ethanol solution.
[0042] (3) 0.04 g of PVP with a polymerization degree of K30 is dissolved in the HNO3-ethanol solution prepared in step (1) to obtain a PVP / HNO3-ethanol solution.
[0043] (4) The PVP / HNO3-ethanol solution is dropped into the AgNO3-ethanol solution and stirred for 30 min at a rotation speed of 600 rpm, and then ultrasonic treatment is carried out for 30 min with an ultrasonic power of 800 w.
[0044] (5) The solution after ultrasonic treatment is sealed and placed at room temperature for 14 days, and then the precipitate is centrifugally washed with deionized water and absolute ethanol for 50 min in sequence until the pH of the upper layer liquid is 7, wherein the centrifugal rotation speed with deionized water is 6000 rpm and the centrifugal rotation speed with absolute ethanol is 6000 rpm. The centrifuged precipitate is dried for 72 h at a drying temperature of 60 °C to obtain one-dimensional Ag micro-rods, and the SEM is as Figure 1 shown.
[0045] The size and morphology of the sample are observed by using a scanning electron microscope. From Figure 1It can be seen that after observation, the one-dimensional Ag microrods with uniform morphology and size and attached with nanosilver particles prepared in this embodiment have good monodispersity, relatively uniform size distribution of nanosilver particles, a side length of 5.666μm, and an Ag yield of 88.73%; after the prepared one-dimensional Ag microrods with nanosilver particles attached with this size are placed for three months, their size and morphology remain almost unchanged, indicating that the one-dimensional Ag microrods prepared by this method are very stable.
[0046] The microscopic morphology characteristics of the one-dimensional Ag microrods prepared in this embodiment are as follows: Figure 1 As shown in the figure, it can be seen that the Ag microrod material obtained is in a one-dimensional rod shape; in the system of ethanol solution with nitric acid, the PVP molecule transfers to the Ag through the NC=O group on its pyrrole ring. + The ions provide electrons to drive the silver ions to be reduced to atoms and gradually aggregate to form crystal nuclei. As the reduction reaction continues, the newly generated Ag atoms are deposited directionally on the surface of the crystal nuclei. At this time, the selective adsorption mechanism of PVP plays a key role: its NC=O group preferentially adsorbs on specific crystal faces of silver crystals (such as the {100} face), and significantly inhibits the atomic deposition rate of the crystal face by changing the surface energy. This crystal face-specific adsorption behavior is combined with the inherent growth dynamics of different crystal faces to form a differentiated growth mode - the crystal faces that are not strongly adsorbed by PVP (such as the {111} face) maintain a higher growth rate, while the growth of the strongly adsorbed crystal faces is hindered. Finally, the controllable preparation of micron-sized silver rods is achieved through anisotropic growth regulation. This process is essentially a precise regulation of the molecular-crystal interface, and nitrate (NO3 - ) and Ag + Formation of complexes (such as Ag(NO3)2 - ), which changes the reduction kinetics of silver ions. The formation of the complex slows down the reduction rate, giving the crystals more time to grow in a specific direction and promoting anisotropy. In this process, PVP not only acts as a morphology directing agent to regulate the formation of one-dimensional structure, but also forms a functional layer of nanosilver attached on the surface of the silver rod through surface passivation, forming a unique micro-nano composite structure.
[0047] Example 2
[0048] A method for preparing one-dimensional Ag microrods comprises the following steps:
[0049] (1) Add 0.3 g of nitric acid dropwise to 10 mL of ethanol solution to obtain HNO3-ethanol solution.
[0050] (2) Dissolve 0.4 g of AgNO3 in 10 mL of ethanol to obtain an AgNO3-ethanol solution.
[0051] (3) Dissolve 0.08 g of PVP with a polymerization degree of K60 into the HNO3-ethanol solution prepared in step (1) to obtain a PVP / HNO3-ethanol solution.
[0052] (4) Drop the PVP / HNO3-ethanol solution into the AgNO3-ethanol solution and stir for 40 min at a rotation speed of 600 rpm, then perform ultrasonic treatment for 45 min with an ultrasonic power of 500 w.
[0053] (5) Seal the solution after ultrasonic treatment and place it at room temperature for 17 days. Then, centrifuge and wash the precipitate with deionized water and absolute ethanol for 40 min each until the pH of the upper layer solution is 7. The centrifugation speed for deionized water is 7000 rpm, and the centrifugation speed for absolute ethanol is 7000 rpm. Dry the centrifuged precipitate for 72 h at a drying temperature of 60 °C to obtain one-dimensional Ag micro-rods. The SEM is as Figure 2 shown.
[0054] The size and morphology of the sample were observed by scanning electron microscopy. It can be seen from Figure 2 that the prepared one-dimensional Ag micro-rods with attached nano-silver particles in this example have uniform morphology and size, good monodispersity, relatively uniform particle size distribution, a side length of 3.860 μm, and an Ag yield of 86.36%. After being placed for three months, the size and morphology of the one-dimensional Ag micro-rods with attached nano-silver particles of this size hardly change, indicating that the one-dimensional Ag micro-rods prepared by this method are very stable.
[0055] Example 3
[0056] A method for preparing one-dimensional Ag micro-rods, comprising the following steps:
[0057] (1) Drop 0.5 g of nitric acid into 10 mL of ethanol solution to obtain an HNO3-ethanol solution.
[0058] (2) Dissolve 0.7 g of AgNO3 in 10 mL of ethanol to obtain an AgNO3-ethanol solution.
[0059] (3) Dissolve 0.14 g of PVP with a polymerization degree of K90 into the HNO3-ethanol solution prepared in step (1) to obtain a PVP / HNO3-ethanol solution.
[0060] (4) Drop the PVP / HNO3-ethanol solution into the AgNO3-ethanol solution and stir for 50 min at a rotation speed of 600 rpm, then perform ultrasonic treatment for 60 min with an ultrasonic power of 200 w.
[0061] (5) Seal the solution after ultrasonic treatment and place it at room temperature for 21 days. Then, centrifuge and wash the precipitate with deionized water and absolute ethanol for 30 min each until the pH of the supernatant is 7. The centrifugation speed for deionized water is 8000 rpm, and the centrifugation speed for absolute ethanol is 8000 rpm. Dry the centrifuged precipitate for 72 h at a drying temperature of 60 °C to obtain one-dimensional Ag micro-rods. The SEM is as shown in Figure 3 shown.
[0062] Use a scanning electron microscope to observe the size and morphology of the sample. As can be seen from Figure 3 it, one-dimensional Ag micro-rods with attached nano-silver particles having uniform morphology and size are prepared in this example. It has good monodispersity, a relatively uniform particle size distribution, a side length of 3.869 μm, and an Ag yield of 82.57%. After being placed for three months, the size and morphology of the one-dimensional Ag micro-rods with attached nano-silver particles of this size hardly change, indicating that the one-dimensional Ag micro-rods prepared by this method are very stable.
[0063] Comparative Example 1
[0064] As a control, the difference between this example and Example 1 is that no nitric acid-ethanol solution is prepared. The specific implementation steps are as follows:
[0065] (1) Dissolve 0.2 g of AgNO3 in 10 mL of ethanol to obtain an AgNO3-ethanol solution.
[0066] (2) Dissolve 0.04 g of PVP with a polymerization degree of K30 in 10 mL of ethanol to obtain a PVP-ethanol solution.
[0067] (3) Drop the PVP-ethanol solution into the AgNO3-ethanol solution and stir for 30 min at a rotation speed of 600 rpm, then perform ultrasonic treatment for 35 min at an ultrasonic power of 800 w.
[0068] (4) Seal the solution after ultrasonic treatment and place it at room temperature for 17 days. Then, centrifuge and wash the precipitate with deionized water and absolute ethanol for 50 min each until the pH of the supernatant is 7. The centrifugation speed for deionized water is 6000 rpm, and the centrifugation speed for absolute ethanol is 6000 rpm. Dry the centrifuged precipitate for 72 h at a drying temperature of 60 °C to obtain silver particles. The SEM is as shown in Figure 4 shown.
[0069] Use a scanning electron microscope to observe the size and morphology of the sample. As can be seen from Figure 4It can be seen that only a small amount of spherical silver particles with severe aggregation are obtained by observation during the preparation. The reason is that when nitric acid is not added, the solution is close to neutral or weakly acidic. At this time, the adsorption of PVP is relatively uniform, resulting in isotropic growth, and Ag + is rapidly reduced in a free form, with a high nucleation rate, leading to the formation of spherical particles.
[0070] Comparative Example 2
[0071] As a control, the difference between this example and Example 1 is that the addition amount of PVP for particle preparation is larger. The specific implementation steps are as follows:
[0072] (1) 0.1 g of nitric acid was added dropwise to 10 mL of ethanol solution to obtain a HNO3-ethanol solution.
[0073] (2) 0.2 g of AgNO3 was dissolved in 10 mL of ethanol to obtain an AgNO3-ethanol solution.
[0074] (3) 0.2 g of PVP with a polymerization degree of K30 was dissolved in the HNO3-ethanol solution prepared in step (1) to obtain a PVP / HNO3-ethanol solution.
[0075] (4) The PVP / HNO3-ethanol solution was added dropwise to the AgNO3-ethanol solution and stirred for 30 min at a rotation speed of 600 rpm. Then, ultrasonic treatment was carried out for 30 min with an ultrasonic power of 800 w.
[0076] (5) The solution after ultrasonic treatment was sealed and left at room temperature for 14 days. Then, the precipitate was centrifugally washed with deionized water and absolute ethanol for 50 min until the pH of the upper layer solution was 7. Among them, the centrifugal rotation speed for deionized water was 6000 rpm, and the centrifugal rotation speed for absolute ethanol was 6000 rpm. The centrifuged precipitate was dried for 72 h at a drying temperature of 60 °C to obtain silver particles. The SEM is as Figure 5 shown.
[0077] The size and morphology of the sample were observed by using a scanning electron microscope. It can be seen from Figure 5 that the products obtained by observation during the preparation are spherical-like silver grains, flaky silver, silver wires, triangular-like silver grains, etc. The reason is that the addition amount of PVP is 0.2 g. A higher concentration of PVP will lead to a mismatch between the reduction rate and adsorption rate of Ag, resulting in the reduction of some Ag+ without being adsorbed by PVP, and isotropic growth occurs, and then it is reduced to spherical silver nanoparticles or elemental Ag with other morphologies. Thus, the proportion of anisotropic growth of silver particles decreases, and then a large number of Ag particles with irregular shapes appear.
[0078] Comparative Example 3
[0079] As a control, the difference between this example and Example 1 lies in that the stirring time is shorter, the rotation speed is lower, and the standing time is shorter during the preparation process. The specific implementation steps are as follows:
[0080] (1) 0.1 g of nitric acid was added dropwise to 10 mL of ethanol solution to obtain an HNO3 - ethanol solution.
[0081] (2) 0.2 g of AgNO3 was dissolved in 10 mL of ethanol to obtain an AgNO3 - ethanol solution.
[0082] (3) 0.04 g of PVP with a polymerization degree of K30 was dissolved in the HNO3 - ethanol solution prepared in step (1) to obtain a PVP / HNO3 - ethanol solution.
[0083] (4) The PVP / HNO3 - ethanol solution was added dropwise to the AgNO3 - ethanol solution and stirred for 20 min at a rotation speed of 200 rpm. Then, ultrasonic treatment was carried out for 30 min with an ultrasonic power of 800 w.
[0084] (5) The solution after ultrasonic treatment was sealed and placed at room temperature for 7 days. Then, the precipitate was centrifugally washed with deionized water and absolute ethanol for 50 min in sequence until the pH of the upper layer solution was 7. The centrifugation speed with deionized water was 6000 rpm, and the centrifugation speed with absolute ethanol was 6000 rpm. The centrifuged precipitate was dried for 72 h at a drying temperature of 60 °C to obtain silver particles. The SEM is as Figure 6 shown.
[0085] The size and morphology of the sample were observed using a scanning electron microscope. It can be seen from Figure 6 that in addition to the one - dimensional Ag micrometer rods with attached nano - silver particles in the prepared product, there are also spherical - like nano - silver particles. The reason is that due to the short stirring time and low rotation speed, the solution was not fully and uniformly mixed, and the standing time was too short. The nano - silver particles did not fully grow anisotropically into micrometer silver rods, resulting in the formation of one - dimensional Ag nanorods and spherical - like nano - silver particles.
[0086] Comparative Example 4
[0087] As a control, the difference between this example and Example 1 lies in the placement temperature in step (5). The specific implementation steps are as follows:
[0088] (1) 0.1 g of nitric acid was added dropwise to 10 mL of ethanol solution to obtain an HNO3 - ethanol solution.
[0089] (2) 0.2 g of AgNO3 was dissolved in 10 mL of ethanol to obtain an AgNO3 - ethanol solution.
[0090] (3) Dissolve 0.04 g of PVP with a degree of polymerization of K30 in the HNO3-ethanol solution prepared in step (1) to obtain a PVP / HNO3-ethanol solution.
[0091] (4) PVP / HNO3-ethanol solution was added dropwise to AgNO3-ethanol solution and stirred for 30 min at a speed of 600 rpm, followed by ultrasonic treatment for 30 min at an ultrasonic power of 800 w.
[0092] (5) The solution after ultrasonic treatment was sealed and placed at a constant temperature of 50 degrees for 7 days, and then the precipitate was centrifuged and washed with deionized water and anhydrous ethanol for 50 minutes in sequence until the pH of the upper liquid was 7, wherein the centrifugal speed for deionized water was 6000 rpm, and the centrifugal speed for anhydrous ethanol was 6000 rpm. The precipitate after centrifugation was dried for 72 hours at a drying temperature of 60°C to obtain silver particles. SEM was as follows Figure 7 shown.
[0093] The size and morphology of the samples were observed using a scanning electron microscope. Figure 7 It can be seen that the prepared products are spherical silver nanoparticles and fewer one-dimensional Ag microrods. The reason is that due to the high placement temperature, the {100} plane of the silver crystal obtains a large amount of energy, the silver particles grow isotropically, and the {111} growth of the silver crystal is hindered, ultimately resulting in spherical silver nanoparticles and fewer one-dimensional Ag microrods.
[0094] Comparative Example 5
[0095] As a comparison, the difference between this embodiment and embodiment 1 is that the solvent used is ethylene glycol solution, and the specific implementation steps are:
[0096] (1) Add 0.1 g of nitric acid dropwise to 10 mL of ethylene glycol solution to obtain HNO3-ethylene glycol solution.
[0097] (2) Dissolve 0.2 g of AgNO3 in 10 mL of ethylene glycol to obtain an AgNO3-ethylene glycol solution.
[0098] (3) 0.04 g of PVP with a degree of polymerization of K30 was dissolved in the HNO3-ethylene glycol solution prepared in step (1) to obtain a PVP / HNO3-ethylene glycol solution.
[0099] (4) The PVP / HNO3-ethylene glycol solution was added dropwise to the AgNO3-ethylene glycol solution and stirred for 30 min at a speed of 600 rpm, and then ultrasonic treatment was performed for 30 min at an ultrasonic power of 800 w.
[0100] (5) Seal the solution after ultrasonic treatment and leave it at room temperature for 14 days. Then, centrifuge and wash the precipitate successively with deionized water and absolute ethanol for 50 min until the pH of the supernatant is 7. The centrifugation speed for deionized water is 6000 rpm, and the centrifugation speed for absolute ethanol is 6000 rpm. Dry the centrifuged precipitate for 72 h at a drying temperature of 60 °C.
[0101] In this example, since AgNO3 was not reduced and the reaction did not proceed, the dried precipitate was a pale yellow transparent film, which was a mixed solid of PVP and AgNO3. This indicates that PVP only played the role of a surfactant in the acidic ethylene glycol solution environment and did not play a reducing role, and elemental Ag could not be obtained.
[0102] Comparative Example 6
[0103] As a control, the difference between this example and Example 1 is that in step (3), a small amount of ascorbic acid was additionally added to form a mixed ethanol solution of ascorbic acid and PVP. The specific implementation steps are as follows:
[0104] (1) Add 0.1 g of nitric acid to 10 mL of ethanol solution to obtain an HNO3-ethanol solution.
[0105] (2) Dissolve 0.2 g of AgNO3 in 10 mL of ethanol to obtain an AgNO3-ethanol solution.
[0106] (3) Dissolve 0.04 g of PVP with a polymerization degree of K30 and 0.1 g of ascorbic acid in the HNO3-ethanol solution prepared in step (1) to obtain a PVP / HNO3-ethanol solution.
[0107] (4) Drop the PVP / HNO3-ethanol solution into the AgNO3-ethanol solution and stir for 30 min at a rotation speed of 600 rpm, and then perform ultrasonic treatment for 30 min with an ultrasonic power of 800 w.
[0108] (5) Seal the solution after ultrasonic treatment and leave it at room temperature for 14 days. Then, centrifuge and wash the precipitate successively with deionized water and absolute ethanol for 50 min until the pH of the supernatant is 7. The centrifugation speed for deionized water is 6000 rpm, and the centrifugation speed for absolute ethanol is 6000 rpm. Dry the centrifuged precipitate for 72 h at a drying temperature of 60 °C to obtain silver particles. The SEM is as Figure 8 shown.
[0109] Use a scanning electron microscope to observe the size and morphology of the sample. From Figure 8It can be seen that the mainly obtained product by observation is micron-sized spherical silver with a smooth surface, having a diameter of 1.132 μm and an Ag yield of 83.31%. Under the action of the reducing agent ascorbic acid, the growth of single-crystal Ag is mainly affected by thermodynamic factors, forming more micron-sized particles with smaller sizes and uniform morphologies. All Ag seeds in the reaction grow isotropically, resulting in the product being micron-sized silver particles. And affected by the dispersion of PVP, well-dispersed micron-sized silver particles are formed, without the generation of one-dimensional Ag micron rods.
[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.
Claims
1. A preparation method for flexible electronic one-dimensional micro silver rods, characterized in that: It includes the following steps: (1) Drop HNO3 into the ethanol solution to obtain an HNO3-ethanol solution; (2) Dissolve AgNO3 in the ethanol solution to obtain an AgNO3-ethanol solution; (3) Dissolve PVP in the HNO3-ethanol solution prepared in step (1) to obtain a PVP / HNO3-ethanol solution; (4) Drop the PVP / HNO3-ethanol solution obtained in step (3) into the AgNO3-ethanol solution prepared in step (2), and stir and perform ultrasonic treatment; (5) Seal the solution after ultrasonic treatment and let it stand at room temperature to obtain a precipitate, and then centrifuge, wash, and dry the precipitate to obtain micro silver rods.
2. The preparation method of the flexible electronic one-dimensional micron silver rod according to claim 1, characterized in that: In step (1), the concentration of HNO3 in the HNO3-ethanol solution is 0.01 - 0.05 g / mL.
3. The preparation method of the flexible electronic one-dimensional micron silver rod according to claim 1, wherein: In step (2), the concentration of AgNO3 in the AgNO3-ethanol solution is 0.02 - 0.07 g / mL.
4. The preparation method of the flexible electronic one-dimensional micro silver rod according to claim 1, characterized in that: In step (3), the concentration of PVP in the PVP / HNO3-ethanol solution is 0.004 - 0.014 g / mL, and the degree of polymerization of PVP is K30 - K90.
5. The preparation method of the flexible electronic one-dimensional micron silver rod according to claim 1, characterized in that: In step (4), the volume ratio of the AgNO3-ethanol solution to the PVP / HNO3-ethanol solution is 1:
1.
6. The preparation method of the flexible electronic one-dimensional micron silver rod according to claim 1, characterized in that: In step (4), the stirring time is 10 - 40 min, the ultrasonic treatment time is 30 - 60 min, and the ultrasonic treatment power is 200 - 800 w.
7. The preparation method of the flexible electronic one-dimensional micron silver rod according to claim 1, wherein: In step (5), the time for standing at room temperature is 14 - 21 days.
8. The preparation method of the flexible electronic one-dimensional micron silver rod according to claim 1, wherein: In step (5), the centrifugation conditions are 6000 - 8000 rpm, and the centrifugation time is 30 - 50 min.
9. The preparation method of the flexible electronic one-dimensional micron silver rod according to claim 1, wherein: In step (5), the drying temperature is 60 - 80 °C, and the drying time is 48 - 72 h.