Preparation method of flexible carbon paper / multitwin gold nanostructure SERS substrate and use thereof

Abstract

The application discloses a preparation method of a flexible carbon paper / multitwin gold nanostructure surface Raman enhancement (SERS) substrate, which comprises the following steps: S1, a three-electrode system is built by taking dilute sulfuric acid as an electrolyte, gold nanorods as a counter electrode, Ag / AgCl as a reference electrode, and carbon paper as a working electrode; S2, gold on the counter electrode is deposited onto the surface of the working electrode by using a linear sweep voltammetry method to form a multitwin gold nanostructure; and S3, the working electrode on which the multitwin gold nanostructure is deposited is cleaned with ultrapure water, and after drying, a flexible carbon paper / multitwin gold nanostructure SERS substrate is obtained. The multitwin gold nanostructure with excellent SERS performance is generated by directly transferring gold from the gold nanorod counter electrode to the carbon paper working electrode through a direct electrotransfer method on the carbon paper, and is used as the SERS substrate.

Description

Technical Field

[0001] This invention relates to a method for preparing a flexible carbon paper / multi-twinned gold nanostructure SERS substrate and its applications, belonging to the field of nanoscience and engineering. Background Technology

[0002] Surface-enhanced Raman scattering (SERS) refers to the surface Raman enhancement effect associated with rough noble metal surfaces (Au, Ag, Cu, etc.), known as the SERS effect. As a versatile spectroscopic analysis technique, it was first discovered in the mid-1970s by British scientists Fleischmann et al., and in recent years has attracted much attention in various fields due to its extremely high sensitivity and selectivity. SERS possesses advantages such as high sensitivity, high resolution, and non-destructive nature, making it a promising candidate for applications in environmental monitoring, food safety, life sciences, and medical diagnostics.

[0003] With the development of materials science and nanotechnology, various SERS substrates have been developed and applied. Currently, the materials used for SERS substrates are mainly noble metals (such as Au, Ag, and Cu). Au nanoparticles can generate strong localized surface plasmon resonances in the visible and near-infrared wavelength ranges, making them effective SERS substrates for enhancing the Raman scattering signal of dye molecules. Various Au nanostructures have been extensively studied as SERS substrates in analytical fields. The morphology, size, interparticle spacing, dielectric properties, and surface characteristics of Au nanostructures all affect their SERS performance. In the solution chemical synthesis of Au nanostructures, ligands or surfactants are usually added to control Au nucleation and growth in order to better regulate their morphology. However, ligands or surfactants on the surface of Au nanostructures often mask their SERS active sites, thereby weakening their SERS performance. Traditional electrodeposition methods generate Au nanostructures on the working electrode by electroreducing Au precursor solutions in an electrolyte solution. However, precisely controlling the electrodeposition rate during this process is difficult, resulting in irregular morphologies of the Au nanostructures prepared on the working electrode. This leads to inconsistent surface properties, making them unsuitable as excellent substrates for SERS (Sequencing-Effect Synthetic Reactors). Therefore, developing a simple and effective electrosynthetic method to precisely control the synthesis of ligand- and surfactant-free Au nanostructures with regular morphologies is of great significance for the development of SERS technology. Summary of the Invention:

[0004] Objective: To address the problems existing in the prior art, this invention uses carbon paper as the working electrode and prepares a high-performance flexible carbon paper / multi-twinned gold nanostructure SERS substrate via an electrotransfer method. Unlike traditional electrodeposition methods, electrotransfer does not require ligands and surfactants. It allows for the controlled and slow transfer of gold directly from the Au counter electrode to the carbon paper working electrode, forming a relatively uniform carbon paper / multi-twinned gold nanostructure SERS substrate rich in SERS hotspots. The prepared carbon paper / multi-twinned gold nanostructure SERS substrate exhibits excellent SERS sensing performance due to its clean surface, absence of ligands and surfactants, and the abundant SERS hotspots imparted by the formed multi-twinned gold nanostructures.

[0005] This invention is achieved through the following technical solution:

[0006] A method for preparing a flexible carbon paper / multi-twinned gold nanostructure SERS substrate includes the following steps:

[0007] S1. A three-electrode system was constructed using dilute sulfuric acid as the electrolyte, gold nanorods as the counter electrode, Ag / AgCl as the reference electrode, and carbon paper as the working electrode.

[0008] S2. Gold elements on the counter electrode are deposited onto the surface of the working electrode using a linear scanning voltammetry method to form a multitwin gold nanostructure.

[0009] S3. The working electrode with deposited multitwinned gold nanostructures is cleaned with ultrapure water and dried to obtain a flexible carbon paper / multitwinned gold nanostructure SERS substrate.

[0010] As a preferred embodiment, the concentration of the dilute sulfuric acid is 0.5M.

[0011] As a preferred embodiment, the gold nanorod has a diameter of 1-3 mm, a length of 1-2 cm, and a length extending into the electrolyte of 0.1-1 cm.

[0012] As a preferred embodiment, the parameters of the linear scanning voltammetry method are set as follows: start and stop voltage is 0 to -0.8V, scanning speed is 0.5mV / s, and the number of scanning cycles is 14 to 17.

[0013] As a preferred embodiment, the number of scanning revolutions is 16 revolutions.

[0014] A method for preparing a flexible carbon paper / multi-twinned gold nanostructure SERS substrate as described above.

[0015] The application of a flexible carbon paper / multi-twinned gold nanostructure SERS substrate, as described above, in dye detection.

[0016] The present invention uses a multi-twinned gold nanostructure electrodeposited on carbon paper as a SERS substrate. By detecting the SERS performance of the flexible carbon paper / multi-twinned gold nanostructure SERS substrate on Rhodamine 6 (R6G), the sensing performance of the Rhodamine 6 (R6G) is demonstrated, which is of great significance in analytical sensing.

[0017] The electrodeposited multitwinned gold nanostructures on carbon paper in this invention, as SERS substrates, exhibit excellent SERS performance. After modification with R6G dye molecules, their detection limit can reach 1×10⁻⁶. -9 M.

[0018] In summary, this material exhibits excellent SERS properties for dye molecules. It shows great application potential in analytical sensing and plays a positive role in promoting the construction of novel SERS substrates. Attached Figure Description

[0019] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0020] Figure 1 (a) is the EDS energy spectrum of the high-performance flexible carbon paper / multi-twinned gold nanostructure SERS substrate prepared in Example 1 of this invention. Figure 1 (b) is the XRD pattern of the high-performance flexible carbon paper / multi-twinned gold nanostructure SERS substrate prepared in this invention. Figure 1 (cd) is the SEM characterization image of the high-performance flexible carbon paper / multi-twinned gold nanostructure SERS substrate prepared in this invention;

[0021] Figure 2 (a) is an HRTEM image of the high-performance flexible carbon paper / multi-twinned gold nanostructure SERS substrate prepared in Example 1 of this invention, used to observe the morphology of the prepared material. Figure 2 (bd) are HRTEM images of different positions on the high-performance flexible carbon paper / multi-twin gold nanostructure SERS substrate prepared in this invention, used to observe the lattice spacing of the prepared material;

[0022] Figure 3 (a) is the XPS full spectrum characterization of the high-performance flexible carbon paper / multi-twinned gold nanostructure SERS substrate prepared in Example 1 of this invention. Figure 3 (b) is the Au 4f high-resolution XPS spectrum of the high-performance flexible carbon paper / multi-twin gold nanostructure SERS substrate prepared in this invention;

[0023] Figure 4 Raman spectra of R6G molecules with different molar concentrations on the high-performance flexible carbon paper / multi-twinned gold nanostructure SERS substrate prepared in Example 1 of this invention;

[0024] Figure 5 The image shows the SEM characterization of the flexible carbon paper / dispersed gold nanoparticle SERS substrate prepared in Comparative Example 1 of this invention.

[0025] Figure 6 The high-performance flexible carbon paper / multi-twinned gold nanostructure SERS substrate prepared in Example 1 of this invention and the flexible carbon paper / gold nanoparticle SERS substrate prepared in Comparative Example 1 have a molar concentration of 10. -6 Comparison of SERS performance of M R6G molecules.

[0026] Figure 7 This is a SEM characterization image of the flexible carbon paper / aggregated gold nanostructure SERS substrate prepared in Comparative Example 2 of this invention.

[0027] Figure 8 The high-performance flexible carbon paper / multi-twinned gold nanostructure SERS substrate prepared in Example 1 of this invention and the flexible carbon paper / aggregated gold nanostructure SERS substrate prepared in Comparative Example 2 have a molar concentration of 10. -6 Comparison of SERS performance of M R6G molecules. Detailed Implementation

[0028] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0029] Example 1

[0030] This embodiment provides a method for preparing a high-performance flexible carbon paper / multi-twinned gold nanostructure SERS substrate, which specifically includes the following steps:

[0031] First, after cleaning the electrolytic cell with ultrapure water, add 12 mL of 0.5 M sulfuric acid solution. Cut carbon paper into 0.5 cm × 6 cm pieces to serve as the working electrode, use a gold electrode as the counter electrode, and use Ag / AgCl as the reference electrode to build a three-electrode system.

[0032] Electrosynthesis was performed using linear scanning voltammetry on an electrochemical workstation with the following parameters: start and stop voltage range of 0 to -0.8 V, 15 scan cycles, and scan rate of 0.5 mV / s. After the electrochemical program was completed, the working electrode was removed with tweezers, rinsed with ultrapure water, and air-dried to obtain a high-performance flexible carbon paper / multi-twinned gold nanostructure SERS substrate.

[0033] The prepared high-performance flexible carbon paper / multi-twinned gold nanostructure SERS substrate was characterized by EDS energy dispersive spectroscopy (EDS). Figure 1 a) It can be determined that the metallic constituent element of the prepared SERS substrate is Au, as shown in the XRD pattern ( Figure 1 b) This reveals the different crystal planes of the multitwinned gold nanostructures on the prepared SERS substrate. The SEM characterization images ( Figure 1 (c, d) Multiple twinned gold nanostructures on the SERS substrate can be observed. The multiple twinned nodes enrich the surface with SERS hotspots, resulting in a good SERS signal. The individual particle size is approximately 60 nm. HRTEM characterization ( Figure 2 )Analyze the lattice data of a high-performance carbon paper / multi-twinned gold nanostructure SERS substrate. From Figure 2 Figure a shows that the Au nanostructures on the prepared SERS substrate have a multi-twinned morphology. The multi-twinned gold nanostructures, due to their rough surface and the interfacial tension caused by lattice mismatch at the twin bonding sites, can become hotspots in SERS. Flexible carbon paper and multi-twinned gold nanostructures can synergistically enhance chemical and electromagnetic fields through Raman spectroscopy, thereby constructing a high-performance SERS substrate. From... Figure 2 Figure b clearly shows the lattice fringes of the multi-twinned gold nanostructure, preliminarily demonstrating the crystallinity of our prepared high-performance flexible carbon paper / multi-twinned gold nanostructure SERS substrate; lattice measurements were performed at multiple sites. Figure 2 The lattice fringe spacing of b is 0.235 nm, corresponding to the (111) crystal plane of Au. From the XPS spectrum ( Figure 3 The binding energy positions of Au can be clearly seen, further proving the formation of Au nanostructures.

[0034] SERS performance testing of R6G dye molecules on flexible carbon paper / multi-twinned gold nanostructure SERS substrate: A molar concentration gradient of 10 was prepared using ultrapure water. -4 M to 10 -10 The high-performance flexible carbon paper / multi-twinned gold nanostructure SERS substrate was cut into 0.5cm × 0.5cm pieces and immersed in 10mL of R6G solutions of different molar concentrations for 10h. After immersion, the pieces were rinsed with ultrapure water and dried with argon gas. Raman spectroscopy was performed on the flexible carbon paper / multi-twinned gold nanostructure SERS substrate with different molar concentrations using a 532nm excitation wavelength laser to detect the R6G molecules at different molar concentrations. Figure 4 As can be seen from the figure, at 1360cm -1 The location can be detected 10 -8 The Raman signal of the M R6G molecule can be detected with a limit of 10. -9 M. Flexible carbon paper / multi-twinned gold nanostructure SERS substrate exhibits excellent SERS properties for R6G molecules.

[0035] Comparative Example 1

[0036] The only difference between this comparative example and Example 1 is that the linear scanning voltammetry uses 10 scan cycles. Apart from the difference in the number of scan cycles, all other parameters and materials remain unchanged, and the SERS performance of the two examples under 532nm laser light shows a significant difference. (SEM characterization images are shown below.) Figure 5 It can be seen that the Au nanostructures synthesized under these conditions are dispersed gold nanoparticles and cannot form the multitwinned gold nanostructures of Example 1. Figure 6 As shown, the SERS performance of the flexible carbon paper / multi-twinned gold nanostructure SERS substrate obtained with 15 scans is better than that of the flexible carbon paper / dispersed gold nanoparticle SERS substrate obtained with 10 scans.

[0037] Comparative Example 2

[0038] The only difference between this comparative example and Example 1 is that the start and stop voltage range is 0 to -1.2V. (SEM characterization image) Figure 7 It can be seen that the gold nanostructures formed in the voltage range of 0 to -1.2V are too dense and unevenly distributed, resulting in a significant difference in SERS performance under 532nm laser compared to Example 1. Figure 8 As shown, the SERS intensity of the flexible carbon paper / multi-twinned gold nanostructure SERS substrate prepared with a start-stop voltage range of 0 to -0.8 V is slightly higher than that of the flexible SERS substrate prepared with a start-stop voltage range of 0 to -1.2 V. In summary, the SERS performance of the uniform multi-twinned gold nanostructure prepared with a start-stop voltage range of 0 to -0.8 V is better than that of the overly densely packed gold nanostructure prepared with a start-stop voltage range of 0 to -1.2 V.

[0039] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing a flexible carbon paper / multi-twinned gold nanostructure SERS substrate, characterized in that, Includes the following steps: S1. A three-electrode system was constructed using dilute sulfuric acid as the electrolyte, gold nanorods as the counter electrode, Ag / AgCl as the reference electrode, and carbon paper as the working electrode. S2. Gold on the counter electrode is transferred to the surface of the working electrode using a linear scanning voltammetry method to form a multitwinned gold nanostructure. S3. The working electrode with deposited multitwinned gold nanostructures is cleaned with ultrapure water and dried to obtain a flexible carbon paper / multitwinned gold nanostructure SERS substrate.

2. The method for preparing the flexible carbon paper / multi-twinned gold SERS substrate as described in claim 1, characterized in that, The concentration of the dilute sulfuric acid is 0.1–0.5 M.

3. The method for preparing the flexible carbon paper / multi-twinned gold nanostructure SERS substrate as described in claim 1, characterized in that, The gold nanorods have a diameter of 1–3 mm, a length of 1–2 cm, and a length extending into the electrolyte of 0.1–1.0 cm.

4. The method for preparing the flexible carbon paper / multi-twinned gold nanostructure SERS substrate as described in claim 1, characterized in that, The parameters of the linear scanning voltammetry method are set as follows: start and stop voltage is 0 to -0.8V, scanning speed is 0.5mV / s, and the number of scanning revolutions is 14 to 17.

5. The method for preparing the flexible carbon paper / multi-twinned gold nanostructure SERS substrate as described in claim 4, characterized in that, The number of scans is 16.

6. A method for preparing a flexible carbon paper / multi-twinned gold nanostructure SERS substrate obtained by the preparation method according to any one of claims 1 to 5.

7. The use of the flexible carbon paper / multi-twinned gold nanostructure SERS substrate as described in claim 6 in dye detection.

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