Ag / na2ti3o7 composite material substrate with sers activity and preparation method thereof

Abstract

The application provides an Ag / Na2Ti3O7 composite material substrate with SERS activity and a preparation method thereof. A synergistic effect between a metal / semiconductor nanocomposite material can produce or obtain field-enhanced light absorption, enhanced luminescence, protein detection capacity and excellent electrocatalytic performance, etc. The application combines the super-sensitive technology of SERS. A sodium titanate nanowire array structure is prepared on a titanium sheet by using a hydrothermal method, and Ag particles with a diameter of 5nm are deposited on the nanowire by using a magnetron sputtering device. In the sputtering process, a series of composite materials with different Ag contents are prepared by changing the sputtering time of the silver target, and the Raman signal intensity of a probe molecule is significantly changed.

Description

Technical Field

[0001] This invention belongs to the field of nanotechnology and detection. A novel method for detecting probe molecules was developed using surface-enhanced Raman scattering (SERS) technology, employing a novel method to prepare Ag / Na₂Ti₃O₇ composite material as a substrate via hydrothermal synthesis and magnetron sputtering. Background Technology

[0002] Since its discovery on rough silver electrode surfaces in 1974, SERS technology has gained increasing attention and is widely used in many fields, such as ultrasensitive detection, bioanalysis, biomedicine, and medical diagnostics, due to its high sensitivity, high selectivity, and ability to achieve non-destructive testing. SERS relies on the large Raman signal enhancement that occurs when analytes are adsorbed on SERS "hot spots" (regions of strong local electric field intensity, typically at the edges and tips of irregular gold, silver, or other plasmonic noble metal nanoparticles). Adding metal nanoparticles to the aforementioned fractal semiconductor surface can enhance the Raman scattering cross-section of molecules adsorbed on its surface through the SERS phenomenon. The structural properties of individual nanoparticles (e.g., morphology, size, and size distribution) are crucial for sensing applications, as even small fluctuations in these parameters can significantly affect the device's sensitivity. To prepare SERS substrates, noble metal (Au, Ag, or Cu) nanoparticles are typically deposited on the surface of a substrate, with controlled size, shape, density, and spacing between particles. Among various metal deposition methods, magnetron sputtering is used to fabricate nanoparticles, offering excellent control over their size, morphology, and distribution.

[0003] SERS typically includes electromagnetic and chemical enhancement, and these two enhancements coexist in metal-semiconductor composites. For metal / semiconductor nanocomposites, their synergistic effects can generate or achieve enhanced light absorption, enhanced luminescence, protein detection capabilities, and excellent electrocatalytic performance. Combining this with the ultrasensitive technology of SERS also holds broad application prospects. Utilizing the flexible structure of organic molecules, the work function can be adjusted by adsorbing 4-mercaptobenzoic acid (4-MBA) organic molecules as SERS probes and performing appropriate modifications to improve their performance, thereby continuously enhancing the performance of metal / semiconductor composite nanosystems. Summary of the Invention

[0004] This invention addresses the synergistic effect between metal / semiconductor nanocomposites, which can generate or achieve enhanced light absorption, enhanced luminescence, protein detection capabilities, and excellent electrocatalytic performance. By combining this with the ultrasensitive SERS technology, a SERS-active Ag / Na2Ti3O7 composite substrate and its preparation method are proposed.

[0005] The present invention discloses an Ag / Na2Ti3O7 composite material substrate with SERS activity, which is composed of an array structure of sea urchin-shaped sodium titanate nanowires grown on the surface of a titanium sheet and Ag nanoparticles grown on the sodium titanate nanowires, wherein the diameter of the sea urchin-shaped sodium titanate nanowires is 3500 nm and the diameter of the Ag nanoparticles is 5 nm.

[0006] The specific steps for preparing the SERS-active Ag / Na2Ti3O7 composite substrate are as follows:

[0007] 1) A sea urchin-shaped sodium titanate nanowire array structure was prepared on a titanium sheet using a hydrothermal method; the specific steps are as follows:

[0008] A. Polish the 3cm×3cm titanium sheet with sandpaper, then clean it with ethanol and deionized water in sequence for 10 minutes. Soak the cleaned titanium sheet in deionized water for later use.

[0009] B. Take 25 mL of a 1 mol / L solution. -1 NaOH solution was added to a high-pressure vessel lined with polytetrafluoroethylene, and the titanium sheet cleaned in step A was added. The reaction was carried out at 180°C for 48 hours to obtain a sodium titanate nanowire array. The titanium sheet obtained from the reaction was ultrasonically cleaned with deionized water, dried in a vacuum drying oven, and then stored for later use.

[0010] 2) Ag particles with a diameter of approximately 5 nm were sputtered onto sodium titanate nanowires using magnetron sputtering; the specific steps are as follows:

[0011] The Ag target is installed on the magnetic target position in the magnetron sputtering cavity, with a target offset angle of 0°. The background gas pressure must be lower than 1.0 × 10⁻⁶ before starting. -6 Pa, set the Ar gas flow rate to control the working gas pressure at 10. -3 The sputtering power of Ag was set to 10W in the Pa range, and the sputtering time was 10–50 s.

[0012] In this invention, the sputtering time of Ag nanoparticles is preferably 50 s.

[0013] The beneficial effects of this invention are:

[0014] 1. The synergistic effect between metal / semiconductor nanocomposites can generate or achieve enhanced light absorption, enhanced luminescence, protein detection capabilities, and excellent electrocatalytic performance.

[0015] 2. The raw materials are abundant, inexpensive, non-toxic and harmless, and can be produced in large quantities.

[0016] 3. The hydrothermal synthesis reaction is simple to operate, and the material obtained by sputtering is uniformly distributed.

[0017] 4. Ag / Na2Ti3O7 materials have abundant "hot spots", which maximizes the SERS effect. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the preparation process of the present invention.

[0019] Figure 2 This is a schematic diagram of the magnetron sputtering steps of the present invention.

[0020] Figure 3 The images are SEM images of the Na2Ti3O7 nanowire array (a) and the sputtered Ag nanoparticles after 10 s (b).

[0021] Figure 4 These are Raman spectra of 4-MBA molecules obtained by exciting Ag / Na2Ti3O7 materials with a 633nm laser in Examples 1-5. Detailed Implementation

[0022] The technical solution of the present invention will be further explained and described below by way of specific embodiments.

[0023] Example 1

[0024] like Figure 1 As shown, the preparation process of the SERS-active Ag / Na2Ti3O7 composite substrate in this embodiment is as follows:

[0025] 1) A sodium titanate nanowire array structure was prepared on a titanium sheet using a hydrothermal method. A 3cm × 3cm titanium sheet was polished with sandpaper, then ultrasonically cleaned sequentially with ethanol and deionized water for 10 min each. The cleaned titanium sheet was then immersed in deionized water for later use. 25 mL of a 1mol / L sodium titanate nanowire array was then prepared. -1 NaOH solution was added to a high-pressure vessel lined with polytetrafluoroethylene, followed by the titanium sheet cleaned in step A. The reaction was carried out at 180°C for 48 hours to obtain a sodium titanate nanowire array. The titanium sheet obtained from the reaction was ultrasonically cleaned with deionized water, dried in a vacuum drying oven, and then stored for use as a substrate for further magnetron sputtering.

[0026] 2) such as Figure 2 As shown, a magnetron sputtering system (ATC 1800-F, AJA, USA) sputters Ag nanoparticles onto a nanowire array. The Ag target is mounted on a magnetic target site within the magnetron sputtering chamber, with a target offset angle of 0°. The background gas pressure must be below 1.0 × 10⁻⁶ before the process begins. -6 Pa sets the Ar gas flow rate to control the working gas pressure at 10. -3 The sputtering power of Ag was set to 10W and the sputtering time was 10s, with the sputtering level in the Pa range.

[0027] likeFigure 3 As shown in the figure, the Na2Ti3O7 nanowires in the array structure are in the shape of sea urchin with an average diameter of about 3500 nm, and the silver with a diameter of about 5 nm is grown on the Na2Ti3O7 nanowires after sputtering.

[0028] The obtained sample is adsorbed with 4-MBA, and the SERS performance of the sample is detected by using 633 nm excitation light to explore the photoelectric properties and light-induced physical processes of the metal / semiconductor / molecule SERS effect. The sea urchin-shaped nanowires provide abundant SERS "hot spots", greatly enhancing the SERS signal of the substrate, as shown in the figure. Figure 4 The Raman spectrum shown in the figure indicates that the Ag / Na2Ti3O7 composite material substrate has good SERS signal.

[0029] Examples 2-5

[0030] Examples 2-5 are different from Example 1 in that the Ag sputtering time is 20 s, 30 s, 40 s and 50 s, respectively. The Raman spectrum indicates that the SERS signal of the Ag / Na2Ti3O7 composite material substrate is enhanced with the extension of the Ag sputtering time.

[0031] In summary, the successfully prepared Ag / Na2Ti3O7 composite material can be used as a promising SERS sensor device, and the experimental results also confirm that the metal / semiconductor / molecule interface plays a key role in the electronic and optical properties of the entire nanosystem.

Claims

1. An Ag / Na2Ti3O7 composite material substrate having SERS activity, characterized by, The substrate is composed of a sea urchin-like sodium titanate nanowire array structure grown on the surface of a titanium sheet and Ag nanoparticles grown on the sodium titanate nanowire, wherein the diameter of the sea urchin-like sodium titanate nanowire is 3500 nm, and the diameter of the Ag nanoparticle is 5 nm.

2. The method for preparing the SERS-active Ag / Na2Ti3O7 composite substrate according to claim 1, characterized in that, The preparation method comprises the following steps: 1) a sea urchin-like sodium titanate nanowire array structure is prepared on a titanium sheet by a hydrothermal method: A. A titanium sheet with a size of 3 cm*3 cm is polished with sandpaper, and then sequentially cleaned with ethanol and deionized water for 10 min, and the cleaned titanium sheet is immersed in deionized water for standby; B. 25 mL of NaOH solution with a concentration of 1 mol / L is added to a polytetrafluoroethylene-lined high-pressure tank, and the cleaned titanium sheet is added, and the reaction is carried out at 180 DEG C for 48 h to obtain a sodium titanate nanowire array, the titanium sheet obtained by reaction is ultrasonically cleaned with deionized water, dried in a vacuum drying box, and then stored for standby; 2) Ag nanoparticles are sputtered on the sodium titanate nanowire by a magnetron sputtering method: The Ag target was loaded on the magnetic target site in the magnetron sputtering cavity, the target site bias angle was 0°, and the background pressure before starting needed to be lower than 1.0×10 -6 Pa, the gas flow of Ar gas was set to control the working gas pressure at the order of 10 -3 Pa, the sputtering power of Ag was set to 10 W, and the sputtering time was 10-50 s.

3. The preparation method according to claim 2, characterized in that, The sputtering time of the Ag nanoparticles is 50 s.

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