Electrochemical preparation method and application of centimeter long silver wire

Abstract

The application discloses an electrochemical preparation method and application of a centimeter-length silver wire, and a mixed solution of silver nitrate, nitric acid and cadmium nitrate is used as an electrolyte, wherein the silver nitrate is a precursor solution, the chromium nitrate is a morphology control agent, and the nitric acid is used for adjusting the pH of the solution; and the silver wire with a centimeter length is prepared through electrodeposition in the electrolyte; the morphology and size of the silver wire can be adjusted by controlling the electrodeposition time, the concentration of the chromium nitrate and the adding amount of the nitric acid; the silver wire can also be prepared by using other oxygen-containing acid radical ions and silver nanoparticles as the morphology control agent in cooperation, and the silver wire can be replicated into a copper and lead system; the silver wire prepared by the application is converted into a porous silver wire by using a silver nitrate solution; and due to the surface-enhanced Raman scattering hot spots and the analyte enrichment function of the porous structure, the porous silver wire can be used as an enhancement substrate for Raman detection of environmental pollutants.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical deposition, and specifically relates to an electrochemical preparation method and application of centimeter-scale long silver wires. Background Technology

[0002] Silver wire, as a one-dimensional metallic material with great application potential, possesses advantages such as high conductivity, high aspect ratio, and excellent flexibility, making it an ideal conductive filler in flexible electronic devices and a core component in plasma applications such as catalysis and sensing. Currently, the main methods for synthesizing silver wire include the polyol method, seed method, template method, and hydrothermal method. As a classic method, researchers have established a silver wire polyol synthesis system using ethylene glycol as a solvent and reducing agent and polyvinylpyrrolidone (PVP) as a structure directing agent. This method is simple, has high yield, and is currently the mainstream industrial synthesis method. However, while PVP guides anisotropic growth, it also firmly adsorbs onto the surface of silver nanowires, forming an organic insulating layer, which limits its application in high-performance scenarios. The template method uses anodic aluminum oxide (AAO) films as templates to grow silver wires within pores through constant current electrodeposition. However, the preparation process of AAO templates is complex and difficult to scale up. In addition, methods such as seed crystal method and hydrothermal method have also been used for silver wire synthesis, but they generally face problems such as harsh reaction conditions, complex reaction system and difficulty in morphology control, which limit their practical application and promotion.

[0003] Therefore, there is an urgent need to develop a method for preparing silver wires that can directly produce high-performance wires with simple synthesis processes and can be mass-produced. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing an electrochemical preparation method and application for centimeter-scale long silver wires. This method prepares centimeter-scale long silver wires at room temperature without using any organic reagents. Uniform silver wires can be prepared simply by passing an electric current through a single solution. The morphology and size of the silver wires can be controlled by adjusting the electrolyte formulation and the electric current conditions. Furthermore, by immersing the silver wires in a silver nitrate solution, a porous structure can be etched, allowing for the preparation of porous silver wires with different degrees of etching.

[0005] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows: In a first aspect, the present invention provides an electrochemical preparation method for silver wires with centimeter-scale lengths, comprising the following steps: passing an electrolyte through a two-electrode system at a voltage of 10 V or a current of 0.07 mA to obtain the centimeter-scale length silver wires.

[0006] Furthermore, the electrolyte composition is: AgNO3, HNO3, Cr(NO3)3 and deionized water, wherein the volume ratio of AgNO3, HNO3, Cr(NO3)3 and deionized water is 1:0.04~0.24:0.04:29.

[0007] Furthermore, the two-electrode system specifically uses a carbon rod as the anode and a silicon wafer as the cathode. When energized, Cr... 3+ It is oxidized to CrO4 2- and Ag in the solution + Ag2CrO4 nanoparticles are formed by combining and synergistically regulating the deposition behavior of silver at the edge of the cathode silicon wafer, enabling its one-dimensional growth.

[0008] Furthermore, the energizing time is 16~46 hours.

[0009] Furthermore, the concentration of chromium nitrate is 0.03~0.3 g / mL. By controlling the concentration of chromium nitrate, silver wires with different morphologies can be prepared; the morphologies include sheet-like structures, equal-width structures, and rough structures.

[0010] Further, the Cr 3+ Replace with MoO4 2- WO4 2- C2O4 2- or IO3 2- .

[0011] Furthermore, copper wire can be prepared by replacing AgNO3 with Cu(NO3)2, and lead wire can be prepared by replacing AgNO3 with Pb(NO3)2.

[0012] Secondly, the present invention also provides a silver wire of centimeter length prepared by the above-described preparation method.

[0013] Thirdly, the present invention also provides an application of the centimeter-length silver wire prepared by the above preparation method in a surface-enhanced Raman substrate.

[0014] Furthermore, the application specifically involves immersing the centimeter-long silver wire in a silver nitrate solution to etch it into a porous silver wire, and then applying the porous silver wire to a surface-enhanced Raman substrate.

[0015] Compared with the prior art, the beneficial effects of the present invention are reflected in: (1) This invention uses a simple electrochemical preparation method to prepare centimeter-long silver wires with uniform size in one step by electrodeposition without the use of organic reagents. The morphology and size of the silver wires can be controlled by adjusting the energizing time, the concentration of chromium nitrate, and the amount of nitric acid added.

[0016] (2) The present invention also has scalability, and can be used to control the morphology of CrO4. 2- Even if Ag2CrO4 nanoparticles are replaced with other oxyacid anions and silver-containing nanoparticles, silver wires can still be prepared and can be replicated in copper and lead systems.

[0017] (3) The present invention further transforms the prepared silver wire into a porous silver wire by immersing it in a silver nitrate solution, and controls the corrosion degree of the porous silver wire by controlling the concentration of silver nitrate. The porous silver wire is then used as a substrate for surface-enhanced Raman scattering for the Raman detection of environmental pollutant R6G. Attached Figure Description

[0018] Figure 1 Figure 1 shows the characterization results of the silver wire obtained by controlling the length of the silver wire by adjusting the energizing time in Example 1. Figure 1a shows the physical images of the silver wire prepared under different energizing times; Figure 2b shows the physical image of the silver wire removed from the electrolyte after 46 hours of energizing; Figure 3c shows the SEM image of the silver wire after alignment, with the inset showing a magnified view; Figure 4d shows a further magnified view of the inset in Figure 4c; Figure 5e shows the XRD pattern of the silver wire; Figure 6f shows the XPS patterns of the silver wire before and after laser etching; Figure 7g shows the Raman pattern of the silver wire; Figure 8h shows the high-resolution TEM image of a transverse ultrathin section of the silver wire, with the right figure showing a magnified view of a local area, and the inset showing the high-resolution TEM image of silver chromate on the surface of the silver wire; Figure 9i shows the high-resolution TEM image of a transverse ultrathin section of the silver wire; and Figure 10j shows the selected area electron diffraction pattern of a transverse ultrathin section of the silver wire. Figure 2 The images shown are SEM images of silver wire width controlled by adjusting the amount of nitric acid added in Example 2; where a is the SEM image of silver wire prepared with 40 μL of nitric acid added; b is the SEM image of silver wire prepared with 120 μL of nitric acid added; and c is the SEM image of silver wire prepared with 240 μL of nitric acid added. Figure 3 In Example 3, the morphology of the silver wire was controlled by adjusting the concentration of chromium nitrate; where a is a SEM image of the silver wire prepared when the concentration of chromium nitrate was 0.03 g / mL; b is a SEM image of the silver wire prepared when the concentration of chromium nitrate was 0.06 g / mL; and c is a SEM image of the silver wire prepared when the concentration of chromium nitrate was 0.3 g / mL. Figure 4 This is an expanded preparation system in Example 4 by replacing the oxyacid anions and the corresponding silver-containing nanoparticles; where a represents replacing Cr(NO3)3 with MoO4. 2- Obtain the SEM image of the silver line; b represents the replacement of Cr(NO3)3 with WO4. 2- Obtain the SEM image of the silver wire; c represents replacing Cr(NO3)3 with C2O4. 2- Obtain the SEM image of the silver line; d represents the value of Cr(NO3)3 replaced with IO3. 2-SEM images of the silver wires were obtained; e represents the replacement of AgNO3 in the electrolyte with Cu(NO3)2 and the addition of MoO4. 2- SEM images of the copper wires were obtained; f represents the replacement of AgNO3 in the electrolyte with Pb(NO3)2 and the addition of CrO4. 2- Obtain the SEM image of the lead wire; Figure 5 The images shown are SEM images from Example 5, illustrating how the corrosion of silver wire was controlled by adjusting the concentration of silver nitrate used for soaking. Image a shows the SEM image of porous silver wire prepared with a silver nitrate concentration of 0.12 g / mL; image b shows the SEM image of porous silver wire prepared with a silver nitrate concentration of 0.06 g / mL; and image c shows the SEM image of porous silver wire prepared with a silver nitrate concentration of 0.024 g / mL. Figure 6 The images shown are Raman spectra of environmental pollutant R6G using a single porous silver wire as a substrate in Application Example 1; where a is the Raman mapping image of the single silver wire loaded with R6G molecules and its corresponding bright-field image and SEM image; b is the Raman spectrum of R6G molecules loaded on the single porous silver wire at different concentrations; c is the 612 cm⁻¹ image. -1 The linear relationship between the Raman peak intensity and the concentration of R6G molecules at a given location. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0020] It should be noted that, unless otherwise specified, the features in the following embodiments and implementation methods can be combined with each other.

[0021] By adjusting the electrolyte formulation and the energizing conditions, the controllable electrochemical preparation of centimeter-long silver wires can be achieved.

[0022] Example 1 This embodiment specifically describes the preparation of silver wires of different lengths.

[0023] (1) Place 0.8 cm Silicon wafers measuring 1.6 cm in size were ultrasonically cleaned for 10 minutes in ethanol and deionized water, respectively.

[0024] (2) Take 4 mL of AgNO3 (concentration of 0.12 g / mL), 160 μL of HNO3 (concentration of 1 mol / L), and 160 μL of Cr(NO3)3 (concentration of 0.06 g / mL) and dissolve them in 116 mL of deionized water (resistivity of 18.25 MΩ·cm) to obtain the electrolyte.

[0025] (3) In the two-electrode system, the silicon wafer described in (1) is used as the cathode, and a carbon rod with a diameter of 5 mm is used as the anode. The distance between the cathode and the anode is maintained at 2.5 cm. A constant voltage of 10 V is applied by an electrochemical workstation, and the energizing time is 0 h, 3 h, 16 h, 26 h, and 46 h, respectively. As the energizing time increases, the silver wire will gradually lengthen, such as Figure 1 As shown in a, it will eventually grow to 5 cm in 46 hours, as... Figure 1 As shown in b; specifically, the silver wire length is approximately 1 cm when the energizing time is 16 h; approximately 3 cm when the energizing time is 26 h; and approximately 5 cm when the energizing time is 46 h.

[0026] The morphology of the obtained silver wire is shown in Figure c, exhibiting a well-uniform size distribution. A magnified view shows that the silver wire has a thickness of 200 nm and a width of 330 nm. Figure 1 As shown in d.

[0027] Figure 1 The XRD results of e show that the obtained linear structures are all crystalline silver and have a large number of (111) crystal planes exposed. Figure 1 XPS results showed that before laser etching, the surface contained not only Ag but also a significant amount of Cr. After etching, the Cr disappeared, proving the presence of Cr-containing substances on the silver wire surface. Furthermore, Figure 1 Raman spectroscopy results showed that the Raman signal on the silver wire surface highly overlapped with the signal of silver chromate, and silver chromate exhibited a similar spectral broadening phenomenon on the silver particle surface, confirming that the Cr-containing substance on the surface was silver chromate. High-resolution TEM results of the cross-section after ultrathin slicing of the silver wire confirmed that the silver wire surface did indeed contain silver chromate, and that it existed in the form of nanoparticles, such as... Figure 1 As shown in h and 1i. Figure 1 The selected electron diffraction results show that, in addition to the diffraction pattern containing crystalline silver, the diffraction pattern of the silver wire also includes polycrystalline diffraction rings containing silver chromate nanoparticles, which fully confirms the presence of polycrystalline silver chromate nanoparticles on the surface of the silver wire.

[0028] Example 2 This embodiment demonstrates the preparation of silver wires of different widths.

[0029] The electrolyte preparation method in Example 1 was modified as follows: 1 mL of AgNO3 (concentration 0.12 g / mL), 40 μL of HNO3 (concentration 1 mol / L), and 40 μL of Cr(NO3)3 (concentration 0.06 g / mL) were dissolved in 29 mL of deionized water (resistivity 18.25 MΩ·cm) to obtain the electrolyte. By changing the amount of HNO3 added to 40 μL, 120 μL, and 240 μL, the CrO4 concentration in the solution could be adjusted. 2- The relative content of Ag₂CrO₄ nanoparticles affects the inhibition of lateral growth of silver crystals, thus controlling the width of the silver wire. When nitric acid is added at 40 μL, the width of the prepared silver wire is approximately 600 nm. Figure 2 As shown in Figure a; when the amount of nitric acid added is 120 μL, the width of the prepared silver wire is approximately 1.5 μm, as shown in Figure a. Figure 2 As shown in b; when the amount of nitric acid added is 240 μL, the width of the prepared silver wire is approximately 4 μm, as shown in b. Figure 2 As shown in c.

[0030] Example 3 This embodiment describes the preparation of silver wires with different morphologies.

[0031] Following the electrolyte preparation method in Example 2, the concentration of CrO4 in the solution can be adjusted by changing the concentration of Cr(NO3)3 added (0.03 g / mL, 0.06 g / mL, 0.3 g / mL). 2- The absolute content of Ag2CrO4 nanoparticles affects the control of silver crystal growth and regulates the morphology of silver wires.

[0032] When the concentration of chromium nitrate is 0.03 g / mL, the prepared silver wire has a sheet-like tandem structure, such as... Figure 3 As shown in a; when the concentration of chromium nitrate is 0.06 g / mL, the prepared silver wire has a uniform width structure, as shown in Figure a. Figure 3 As shown in b; when the chromium nitrate concentration is 0.3 g / mL, the prepared silver wire has a rough structure, as shown in... Figure 3 As shown in c.

[0033] Example 4 This example illustrates the preparation of silver wires in different systems.

[0034] Following the electrolyte preparation method in Example 2, silver wire growth can also be achieved by replacing Cr(NO3)3 with different oxyacid anions. The remaining oxyacid anions and their corresponding silver nanoparticles also exhibit similar one-dimensional growth regulation effects. Specifically, replacing Cr(NO3)3 with MoO4... 2- It can be obtained as follows Figure 4 The silver line shown in a; replace Cr(NO3)3 with WO4. 2-It can be obtained as follows Figure 4 The silver line shown in b; replace Cr(NO3)3 with C2O4. 2- It can be obtained as follows Figure 4 The silver line shown in c; replace Cr(NO3)3 with IO3. 2- It can be obtained as follows Figure 4 The silver line shown in d.

[0035] Example 5 This embodiment describes the preparation of other metal wires.

[0036] Following the electrolyte preparation method in Example 2, the AgNO3 in the electrolyte was replaced with Cu(NO3)2, and MoO4 was added. 2- It can be obtained as follows Figure 4 The copper wire shown in e; replace AgNO3 in the electrolyte with Pb(NO3)2, and add CrO4. 2- It can be obtained as follows Figure 4 The lead wire shown as f.

[0037] Application Example 1 This application example specifically demonstrates the use of porous silver wire in SERS detection.

[0038] The ultra-long silver wire prepared in Example 1 by energizing for 46 hours was then immersed in 10 μL of silver nitrate solution using tweezers, using a single wire approximately 1 mm long. The silver ions activated a galvanic cell reaction between the silver wire and the surface silver chromate, resulting in corrosion. When the concentration of silver nitrate was 0.12 g / mL, the following was prepared: Figure 5 A porous silver wire with moderate to severe corrosion; when immersed in silver nitrate at a concentration of 0.06 g / mL, a wire is prepared as follows: Figure 5 b. A porous silver wire with moderate corrosion; when immersed in silver nitrate at a concentration of 0.024 g / mL, a wire is prepared as follows: Figure 5 c. Porous silver wire with moderate corrosion.

[0039] A moderately etched single porous silver wire was used as a SERS substrate for SERS detection of the environmental pollutant R6G. R6G ethanol solutions of different concentrations were prepared, and the prepared single silver wire was placed in 10 μL of R6G solution. The droplet was concentrated without a container for 30 min using an ultrasonic levitation device. Finally, the concentrated small droplet was collected on a silicon wafer, dried, and the Raman signal was detected. The Raman test conditions were: wavelength 532 nm, laser intensity 3 mW, accumulation time 1 s, and accumulation count 3. To evaluate the uniformity of detection on the single silver wire, Raman mapping tests were performed on the silver wire, such as... Figure 6 As shown in Figure a, the intensity map shows uniform intensity across the silver line, with a relative standard deviation (RSD) of 15.3%, indicating good repeatability of the test. Raman signals of different concentrations of R6G are shown in Figure a. Figure 6 As shown in b, the lowest measurable value is 10. -12 M. At the same time, R6G 612 cm can be... -1 A linear curve was plotted between the logarithm of the peak intensity and the logarithm of the R6G concentration, as shown below. Figure 6 As shown in c, the obtained fitting equation is Log I = 0.21Log C + 5.18, R0 2 The value of 0.989 indicates that the porous silver wire has good Raman quantitative detection capability.

[0040] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only.

[0041] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. An electrochemical preparation method for silver wires with centimeter-scale lengths, characterized in that, Includes the following steps: The centimeter-long silver wire can be obtained by passing an electrolyte through a two-electrode system at a voltage of 10 V or a current of 0.07 mA.

2. The preparation method according to claim 1, characterized in that, The electrolyte consists of AgNO3, HNO3, Cr(NO3)3 and deionized water, wherein the volume ratio of AgNO3, HNO3, Cr(NO3)3 and deionized water is 1:0.04~0.24:0.04:

29.

3. The preparation method according to claim 1, characterized in that, The two-electrode system specifically uses a carbon rod as the anode and a silicon wafer as the cathode. When energized, Cr... 3+ It is oxidized to CrO4 2- and Ag in the solution + Ag2CrO4 nanoparticles are formed by combining and synergistically regulating the deposition behavior of silver at the edge of the cathode silicon wafer, enabling its one-dimensional growth.

4. The preparation method according to claim 1, characterized in that, The power-on time is 16~46 hours.

5. The preparation method according to claim 2, characterized in that, The concentration of chromium nitrate is 0.03~0.3 g / mL. By controlling the concentration of chromium nitrate, silver wires with different morphologies can be prepared. The morphologies include sheet-like structures, equal-width structures, and rough structures.

6. The preparation method according to claim 3, characterized in that, The Cr 3+ Replace with MoO4 2- WO4 2- C2O4 2- or IO3 2- .

7. The preparation method according to claim 2, characterized in that, Copper wire can be prepared by replacing AgNO3 with Cu(NO3)2, and lead wire can be prepared by replacing AgNO3 with Pb(NO3)2.

8. A silver wire of centimeter length prepared by any one of the preparation methods of claims 1-7.

9. The application of a centimeter-long silver wire prepared by any one of the preparation methods of claims 1-7 in a surface-enhanced Raman substrate.

10. The application according to claim 9, characterized in that, The specific application involves immersing the centimeter-long silver wire in a silver nitrate solution to etch it into a porous silver wire, and then applying the porous silver wire to a surface-enhanced Raman substrate.

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