Ag@Cu-VO composite SERS substrate, preparation method thereof and application thereof in SERS detection and / or photocatalytic degradation

Abstract

This invention belongs to the field of SERS detection and organic pollutant degradation, specifically relating to an Ag@Cu-VO composite SERS substrate, its preparation method, and its application in SERS detection and / or photocatalytic degradation. V₂O₅ is dissolved in deionized water, the pH of the solution is adjusted to alkaline, copper nitrate trihydrate is added, the pH of the solution is adjusted to alkaline, the solution is centrifuged, washed, filtered, dried, and calcined to obtain Cu-VO. Silver nanoparticles are obtained by chemical reduction using silver nitrate and sodium borohydride. The SERS substrate is obtained by ultrasonic dispersion to allow silver to adhere to the Cu-VO surface. The composite material of noble metal and semiconductor obtained in this invention, through the synergistic effect of its physical and chemical reinforcement mechanisms, is of great significance for improving the sensitivity, stability, and trace detection of the SERS substrate, and is attributed to Cu. 2+ The synergistic effect between the V2O5 host lattice, the reduction in grain size, the rapid transfer of charge carriers, and the low resistance enhance the photocatalytic degradation activity of organic pollutants.

Description

Technical Field

[0001] This invention belongs to the field of SERS detection and organic pollutant degradation, specifically relating to an Ag@Cu-VO composite SERS substrate, its preparation method, and its application in SERS detection and / or photocatalytic degradation. Background Technology

[0002] Surface-enhanced Raman scattering (SERS) is a powerful tool for trace substance detection, but the development of its core—high-performance SERS substrates—remains challenging. Traditional noble metal substrates (such as gold and silver) rely on electromagnetic field enhancement, offering high sensitivity but at a high cost, limited functionality, and the inability to degrade detected harmful pollutants, easily leading to secondary pollution. Semiconductor materials (such as V₂O₅) are inexpensive and possess photocatalytic potential, but their inherent SERS signals (mainly derived from charge transfer) are typically weak, making it difficult to meet the sensitivity requirements for ultra-trace detection.

[0003] To balance high sensitivity and catalytic function, researchers have combined noble metals with semiconductors, aiming to synergistically enhance electromagnetic and chemical properties. Vanadium pentoxide (V₂O₅) is a semiconductor with a narrow band gap and tunable structure, but its charge separation efficiency and conductivity need further improvement. Transition metal ions (such as Cu) 2+ Doping can effectively regulate the electronic structure of V2O5, reduce grain size and improve conductivity, thereby enhancing its intrinsic charge transfer ability, which is crucial for improving its SERS activity and photocatalytic performance.

[0004] This invention aims to provide a novel method for preparing a Cu-doped V₂O₅ synergistic silver nanoparticle (Ag@Cu-VO) composite SERS substrate. This design optimizes the intrinsic properties of V₂O₅ through Cu doping, and then combines it with silver nanoparticles to fully utilize the synergistic effect between the two. The goal is to obtain a bifunctional material with high sensitivity, good stability, and the ability to rapidly photocatalytically degrade detected pollutants, providing a new technical solution for the on-site monitoring and simultaneous treatment of organic pollutants such as industrial dyes. Summary of the Invention

[0005] To address the problems of existing technologies, this invention provides an application of Ag@Cu-VO composite SERS substrate in SERS detection and photocatalytic degradation.

[0006] The technical solution adopted in this invention is: an Ag@Cu-VO composite SERS substrate, the preparation method of which includes the following steps:

[0007] 1) Dissolve vanadium pentoxide in deionized water, and slowly add ammonia water dropwise under constant stirring to obtain a pale yellow solution. Then add copper nitrate trihydrate to dissolve it, and add ammonia water dropwise again to adjust the pH of the solution to alkaline.

[0008] 2) The precipitate was centrifuged, washed, filtered, and vacuum dried. The dried product was then calcined in a muffle furnace to obtain the sample Cu-VO.

[0009] 3) Solution A was prepared by mixing silver nitrate, ammonia, and hexadecyltrimethylammonium bromide, and solution B was prepared by mixing hexadecyltrimethylammonium bromide, deionized water, and sodium borohydride. After mixing the prepared solutions A and B and stirring continuously for a period of time, silver nanomaterials were obtained.

[0010] 4) After ultrasonically dispersing Cu-VO and a certain proportion of silver for a period of time, the composite was separated by centrifugation, filtered, and vacuum dried to obtain Ag@Cu-VO composite material.

[0011] In the Ag@Cu-VO composite SERS substrate mentioned above, in step 1), the molar ratio of vanadium pentoxide and copper nitrate trihydrate is 20:1.

[0012] In step 1) of the above-mentioned Ag@Cu-VO composite SERS substrate, ammonia water is added dropwise to adjust the pH of the solution to 8.5.

[0013] In step 2) of the above-mentioned Ag@Cu-VO composite SERS substrate, the substrate is calcined at 600 °C for 5 h in a muffle furnace.

[0014] In the above-mentioned Ag@Cu-VO composite SERS substrate, in step 3), the preparation method of solution A is as follows: take 18 mg of hexadecyltrimethylammonium bromide and add it to 100 mL of deionized water, dissolve it in a water bath, wait for it to cool to room temperature, add 34 mg of silver nitrate and 3 mL of ammonia water, and stir until a uniform and transparent solution is formed.

[0015] In step 3) of the above-mentioned Ag@Cu-VO composite SERS substrate, the preparation method of solution B is as follows: 18 mg of hexadecyltrimethylammonium bromide is added to 100 mL of deionized water and dissolved in a water bath. After complete dissolution, the solution is placed in a refrigerator for a period of time. Then, 30.3 mg of sodium borohydride is added and stirred to dissolve the solution B.

[0016] In the Ag@Cu-VO composite SERS substrate mentioned above, in step 4), the ratio of Cu-VO to Ag is 10:1.

[0017] The above-mentioned Ag@Cu-VO composite SERS substrate is used in the detection and / or photocatalytic degradation of methylene blue in water.

[0018] The above application is carried out as follows: Under 785 nm laser irradiation, the Ag@Cu-VO composite SERS substrate is immersed in MB solution, which enhances the Raman signal of MB molecules and facilitates the detection of MB molecules in water.

[0019] The above application is carried out as follows: The Ag@Cu-VO composite SERS substrate is added to a 5 ppm MB solution and photocatalytic degradation reaction is carried out under xenon lamp irradiation and stirring conditions.

[0020] The beneficial effects of this invention can be attributed to two aspects:

[0021] 1. The composite material of noble metal Ag and semiconductor Cu-VO achieves an enhancement effect through the synergistic effect of its physical and chemical enhancement mechanisms: the construction of Ag@Cu-VO composite SERS substrate can increase the specific surface area of ​​the material and provide more "hot spots"; the introduction of Cu-VO accelerates the propagation rate of electrons and holes, thereby enhancing the Raman spectrum of MB molecules.

[0022] 2.Cu 2+ The synergistic effect between the V2O5 host lattice, the reduction in grain size, the rapid transfer of charge carriers, and the low resistance enhance the photocatalytic degradation activity of organic pollutants. Attached Figure Description

[0023] Figure 1 This is a SEM image of Ag@Cu-VO at a scale of 5 μm in Example 1.

[0024] Figure 2 This is a SEM image of Ag@Cu-VO at a scale of 500 nm in Example 1.

[0025] Figure 3 This is the UV-Vis absorption spectrum of the Ag@Cu-VO nanoparticles in Example 1 at 5 ppm MB after photodegradation.

[0026] Figure 4 The graphs show the photocatalytic degradation curves of Ag@Cu-VO nanoparticles at 5 ppm MB in Examples 1 and 2.

[0027] Figure 5 This is a graph showing the photodegradation rate of 5 ppmMB by Ag@Cu-VO nanoparticles in Examples 1 and 2.

[0028] Figure 6 This is the SERS spectrum of different concentrations of MB molecules adsorbed on the Ag@Cu-VO composite substrate under a 785 nm laser in Example 1. Detailed Implementation

[0029] To better understand the technical solution of the present invention, specific embodiments are provided for further detailed description, but the solution is not limited thereto.

[0030] Example 1: An Ag@Cu-VO composite SERS substrate

[0031] The preparation method is as follows:

[0032] 1) Weigh vanadium pentoxide (3.64 g, 0.02 mol) and dissolve it in 100 mL of deionized water. Slowly add ammonia water dropwise under constant stirring to obtain a pale yellow solution. Then add copper nitrate trihydrate (0.24 g, 0.001 mol) and dissolve it. Add ammonia water dropwise again to adjust the pH of the solution to 8.5.

[0033] 2) The precipitate was centrifuged, washed, filtered, and vacuum dried. The dried product was then calcined in a muffle furnace at 600°C for 5 h to obtain the sample Cu-VO.

[0034] 3) Take 18 mg of hexadecyltrimethylammonium bromide and add it to 100 mL of deionized water. Dissolve it in a water bath and let it cool to room temperature. Add 34 mg of silver nitrate and 3 mL of ammonia water and stir until a uniform and transparent solution A is formed. Take 18 mg of hexadecyltrimethylammonium bromide and add it to 100 mL of deionized water. Dissolve it in a water bath and let it dissolve completely. Refrigerate it in a refrigerator. After a period of time, add 30.3 mg of sodium borohydride and stir to dissolve to obtain solution B.

[0035] 4) Mix the prepared solutions A and B, and stir continuously for a period of time to obtain silver nanomaterials;

[0036] 5) Weigh out Cu-VO (40 mg) and silver nanoparticles (4 mg), mix them ultrasonically for a period of time, separate the composite by centrifugation, filter, and vacuum dry to obtain Ag@Cu-VO composite material.

[0037] Example 2: An Ag@Cu-VO composite SERS substrate

[0038] The preparation method is as follows:

[0039] 1) Weigh vanadium pentoxide (3.64 g, 0.02 mol) and dissolve it in 100 mL of deionized water. Slowly add ammonia water dropwise under constant stirring to obtain a pale yellow solution. Then add copper nitrate trihydrate (0.24 g, 0.001 mol) and dissolve it. Add ammonia water dropwise again to adjust the pH of the solution to 8.5.

[0040] 2) The precipitate was centrifuged, washed, filtered, and vacuum dried. The dried product was then calcined in a muffle furnace at 600°C for 5 h to obtain the sample Cu-VO.

[0041] 3) Take 18 mg of hexadecyltrimethylammonium bromide and add it to 100 mL of deionized water. Dissolve it in a water bath and let it cool to room temperature. Add 34 mg of silver nitrate and 3 mL of ammonia water and stir until a uniform and transparent solution A is formed. Take 18 mg of hexadecyltrimethylammonium bromide and add it to 100 mL of deionized water. Dissolve it in a water bath and let it dissolve completely. Refrigerate it in a refrigerator. After a period of time, add 30.3 mg of sodium borohydride and stir to dissolve to obtain solution B.

[0042] 4) Mix the prepared solutions A and B, and stir continuously for a period of time to obtain silver nanomaterials;

[0043] 5) Weigh Cu-VO (20 mg) and silver nanoparticles (4 mg), mix them ultrasonically for a period of time, separate the composite by centrifugation, filter, and vacuum dry to obtain Ag@Cu-VO composite material.

[0044] SEM tests were performed on the Ag@Cu-VO composite material of Example 1, and the test results are as follows: Figure 1 and Figure 2 As shown, from Figure 1 It can be observed that the composite SERS substrate particles are relatively uniformly distributed, but there is a certain degree of agglomeration. Figure 2 It exhibits a relatively rough and irregular morphology, which may correspond to the layered or granular structure of vanadium pentoxide (VO). On its surface, a large number of bright fine particles can be clearly distinguished. These are silver (Ag) nanoparticles that are attached to it. The silver particles are relatively uniformly distributed, and the whole structure forms a silver-modified vanadium-based composite structure.

[0045] Example 3: Application of Ag@Cu-VO composite SERS substrate in photocatalytic degradation of MB molecules in water

[0046] The 5 mg Ag@Cu-VO composite SERS substrates prepared in Examples 1 and 2 were added to 50 mL of 5 ppm MB solution, respectively, and photocatalytic degradation was carried out under xenon lamp irradiation and stirring. The specific process is as follows: Timing was started simultaneously with the xenon lamp irradiation. Approximately 3-4 mL of the mixed solution was taken from the reaction system every 10 minutes at preset time intervals. The obtained samples needed to be immediately centrifuged or filtered. The clear liquid was added to a quartz cuvette, and a UV-Vis spectrophotometer was used to scan in the wavelength range of 500-800 nm. The above steps were repeated until the degradation reaction of MB tended to plateau. The degradation results are as follows: Figure 3 , Figure 4 and Figure 5 As shown. By Figure 3 As can be seen, the main peak (663 nm) gradually decreases and is accompanied by a blue shift during the degradation process, indicating that the degradation reaction proceeds smoothly. Figure 4 and Figure 5 As can be seen, the composite material of Example 1 exhibits better degradation performance than the composite material of Example 2. Figure 4 The degradation rate of Example 1 (53%) was higher than that of Example 2 (43%); the photocatalytic degradation process followed a pseudo-first-order reaction kinetic model and could be expressed using the formula... The experimental data were fitted, and the fitting results are as follows: Figure 5 As shown, the degradation rate of Example 1 was 0.0072 min. -1 ) ratio 2 (0.0055min -1 The degradation effect was greater than that of Example 1 because too much silver adhered to the Cu-VO surface in Example 2, affecting its contact with MB molecules.

[0047] Example 4: Application of Ag@Cu-VO composite SERS substrate in the detection of MB molecules in water

[0048] The prepared Example 1 solution was diluted with water to form a dispersion. A few drops of the dispersion were applied to the cleaned silicon wafer surface and allowed to dry naturally at room temperature to form a uniform thin film substrate. Methylene blue solutions of different concentrations (from high concentration 10) were prepared using deionized water. -4 M to low concentration 10 -8 (M gradient dilution) A few drops of MB solution of a certain concentration were added to a dry Ag@Cu-VO substrate, and the substrate was allowed to stand in the dark for 10-20 minutes to allow for full adsorption. Then, it was air-dried at room temperature. Using a 785nm wavelength laser as the excitation source, SERS technology was used to perform tests on the above substrate. The test results are as follows: Figure 6 As shown. From Figure 6 1618 cm visible in the middle -1 There is a significant signal enhancement at this point, which corresponds to the stretching vibration peak of the CC ring of the MB molecule. Within a certain concentration range, the peak intensity decreases as the concentration decreases.

Claims

1. An Ag@Cu-VO composite SERS substrate, characterized in that, Its preparation method includes the following steps: 1) Dissolve vanadium pentoxide in deionized water, and slowly add ammonia water dropwise under constant stirring to obtain a pale yellow solution. Then add copper nitrate trihydrate to dissolve it, and add ammonia water dropwise again to adjust the pH of the solution to alkaline. 2) The precipitate was centrifuged, washed, filtered, and vacuum dried. The dried product was then calcined in a muffle furnace to obtain the sample Cu-VO. 3) Solution A was prepared by mixing silver nitrate, ammonia, and hexadecyltrimethylammonium bromide, and solution B was prepared by mixing hexadecyltrimethylammonium bromide, deionized water, and sodium borohydride. After mixing the prepared solutions A and B and stirring continuously for a period of time, silver nanomaterials were obtained. 4) After ultrasonically dispersing Cu-VO and a certain proportion of silver for a period of time, the composite was separated by centrifugation, filtered, and vacuum dried to obtain Ag@Cu-VO composite material.

2. The Ag@Cu-VO composite SERS substrate according to claim 1, characterized in that, In step 1), the molar ratio of vanadium pentoxide to copper nitrate trihydrate is 20:

1.

3. The Ag@Cu-VO composite SERS substrate according to claim 1, characterized in that, In step 1), ammonia water is added dropwise to adjust the pH of the solution to 8.

5.

4. The Ag@Cu-VO composite SERS substrate according to claim 1, characterized in that, In step 2), the mixture is calcined at 600 °C for 5 h in a muffle furnace.

5. The Ag@Cu-VO composite SERS substrate according to claim 1, characterized in that, In step 3), the preparation method of solution A is as follows: take 18 mg of hexadecyltrimethylammonium bromide and add it to 100 mL of deionized water, dissolve it in a water bath, and after cooling to room temperature, add 34 mg of silver nitrate and 3 mL of ammonia water, and stir until a uniform and transparent solution is formed.

6. The Ag@Cu-VO composite SERS substrate according to claim 1, characterized in that, In step 3), the preparation method of solution B is as follows: take 18 mg of hexadecyltrimethylammonium bromide and add it to 100 mL of deionized water, dissolve it in a water bath, and after it is completely dissolved, put it in the refrigerator for a period of time. Then add 30.3 mg of sodium borohydride and stir to dissolve to obtain solution B.

7. The Ag@Cu-VO composite SERS substrate according to claim 1, characterized in that, In step 4), the ratio of Cu-VO to Ag is 10:

1.

8. The use of the Ag@Cu-VO composite SERS substrate according to any one of claims 1-7 in the detection and / or photocatalytic degradation of methylene blue in water.

9. The application according to claim 8, characterized in that, The method is as follows: Under 785 nm laser irradiation, the Ag@Cu-VO composite SERS substrate described in any one of claims 1-7 is immersed in MB solution, which enhances the Raman signal of MB molecules and facilitates the detection of MB molecules in water.

10. The application according to claim 8, characterized in that, The method is as follows: The Ag@Cu-VO composite SERS substrate according to any one of claims 1-7 is added to a 5 ppm MB solution, and a photocatalytic degradation reaction is carried out under xenon lamp irradiation and stirring conditions.

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