Silver-cerium dioxide composite nanorod-like material, preparation method and application of silver-cerium dioxide composite nanorod-like material in surface enhanced Raman spectroscopy

Abstract

The invention belongs to the technical field of composite material preparation, and particularly relates to a silver-cerium dioxide composite nanorod-like material, a preparation method and application of the silver-cerium dioxide composite nanorod-like material in surface enhanced Raman spectroscopy. According to the preparation method, the silver nanoparticles and the cerium dioxide nanorods are combined, and the obtained composite nanorod-like material is composed of the CeO2 nanorods with the large diameter (about 500 nm) and the silver nanoparticles with the small size (20-50 nm). The prepared silver-cerium dioxide composite nanorod-like material has excellent detection capability on methylene blue and crystal violet in a surface Raman enhanced spectrum test, and can reach a lower detection limit, so that the silver-cerium dioxide composite nanorod-like material can be used for rapid analysis and detection of trace organic matters.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material preparation, and specifically relates to a silver-cerium dioxide composite nanorod material, a preparation method and application thereof in surface enhanced Raman spectroscopy. Background Art

[0002] Silver-semiconductor composite nanomaterials are a research field that has attracted much attention. This heterogeneous structure combines strong plasma and optoelectronic properties, and has advantages over pure silver nanomaterials and semiconductor nanomaterials. This composite material has a high surface area, excellent chemical stability, and a controllable structural morphology. Researchers optimize the performance and application scenarios of composite nanomaterials through different synthesis methods and surface modification strategies. At present, silver-semiconductor composite nanomaterials have shown broad application prospects in the fields of photocatalysis, photovoltaics, and biomedicine, providing new solutions for improving analytical sensitivity, enhancing catalytic efficiency, and realizing biomedical applications.

[0003] Surface-Enhanced Raman Spectroscopy (SERS) has developed into a powerful spectral analysis technology due to its non-destructive, high sensitivity, and rapid detection characteristics. As an advanced spectral analysis technology, SERS has been widely used in many fields such as pesticide residue detection, surface science analysis, biochemical analysis, and environmental monitoring. Due to its unique fingerprint analysis, it has developed into an important technical means for in-situ analysis on surfaces or interfaces. Due to its outstanding detection sensitivity, it plays an important role in micro- and trace detection.

[0004] At present, there are a large number of silver-semiconductor composite nanomaterials as SERS substrates. Yang et al. prepared SiO 2 @Ag nanoparticles, explore their stability and consistency under different conditions, and find that SiO 2 @Ag nanoparticles have excellent stability and consistency and have excellent Raman detection effect; Xu et al. prepared large-area silver-modified TiO 2 Nanograss, the substrate has good detection rate for both rhodamine 6G and 4-aminothiophenol, and can be self-cleaned and reactivated by visible light irradiation.

[0005] Different substrate materials have different detection effects on specific probe molecules, and the SERS detection sensitivity of the substrate is not high enough, which will also affect the practical application of SERS. Silver nanomaterials are the most commonly used SERS substrate materials, which have significant Raman enhancement effects. However, silver nanoparticles have problems such as high price, easy aggregation, easy oxidation, and poor stability. 2Nanomaterials have the advantages of charge transfer ability and good stability as SERS substrates. Combining the characteristics of silver and cerium dioxide makes it have better Raman performance as a SERS substrate. However, there are no reports on the use of silver-cerium dioxide composite nanorod materials as SERS substrate materials for detection. In addition, the preparation methods of some silver-cerium dioxide composite nanomaterials reported so far are complicated and time-consuming, and some preparation methods may require special equipment. Summary of the invention

[0006] In view of this, the present invention discloses a silver-cerium dioxide composite nanorod material, a preparation method and an application thereof in surface enhanced Raman spectroscopy.

[0007] It should be noted that, since silver nanomaterials produce a strong local plasma resonance effect under visible light irradiation, and play a major role in the Raman scattering electromagnetic field enhancement mechanism (EM), silver nanomaterials have excellent SERS performance as SERS substrates; when probe molecules are adsorbed on the surface of ceria nanomaterials, charge transfer will occur between the two, thereby causing chemical enhancement (CM), and the composite nanostructure can combine the two Raman enhancement mechanisms to have better Raman performance. Therefore, the present invention creatively uses sodium hydroxide and L-ascorbic acid to combine silver nanoparticles with ceria nanorods. The silver-ceria composite nanorod-shaped material combines the electromagnetic enhancement mechanism of silver nanoparticles and the chemical enhancement mechanism of ceria, which work together on the Raman signal to produce a better Raman signal.

[0008] In order to achieve the above object, the present invention adopts the following technical solution:

[0009] The first object of the present invention is to provide a silver-ceria composite nanorod-like material, wherein the composite nanorod-like material is composed of silver nanoparticles and ceria nanorods, the silver nanoparticles are loaded on the surface of the ceria nanorods, the atomic ratio of silver to ceria is 1:10, the diameter of the ceria nanorods is 400-600nm, and the particle size of the silver nanoparticles is 20-50nm.

[0010] The second object of the present invention is to provide a method for preparing the silver-cerium dioxide composite nanorod-shaped material as described above, the method specifically comprising the following steps:

[0011] (1) Preparation of cerium dioxide nanorods:

[0012] Weigh cerium nitrate hexahydrate Ce(NO 3 ) 3 6H 2O was dissolved in distilled water, and then urea was weighed and slowly added to the solution under magnetic stirring; stirred for half an hour, and the resulting solution was colorless and transparent; the solution was poured into a round-bottom flask and stirred in an oil bath. After the reaction, the solution was cooled to room temperature, washed with distilled water by centrifugation, and dried overnight to obtain white rod-shaped alkaline cerium carbonate Ce(OH)CO 3 ; Weigh Ce(OH)CO 3 Add to distilled water, then add NaOH solid, stir at room temperature for half an hour to obtain a milky white solution, then pour into a reactor and perform hydrothermal reaction in an oven; after the reaction is completed, wait for the reactor to cool to room temperature, centrifuge and wash with distilled water and ethanol in turn, and finally obtain CeO with a diameter of 400 to 600 nm after drying. 2 Nanorods;

[0013] (2) Loading silver nanoparticles:

[0014] Add silver nitrate aqueous solution to ionized water, add CeO prepared in step (1) 2 Nanorods are stirred vigorously to form a suspension; the pH value of the suspension is adjusted with a sodium hydroxide solution, and after continuing to stir, the suspension is centrifuged to separate the solid and liquid, and then an L-ascorbic acid solution is added, and the color can be observed to change to black-gray, and the suspension is stirred, centrifuged, washed with deionized water and ethanol, and dried to obtain the silver-cerium dioxide composite nanorod material.

[0015] Optionally, in step (1), the mass ratio of cerium nitrate hexahydrate to urea is 0.9:2 to 1:2; the oil bath stirring reaction temperature is 70 to 90°C, and the time is 20 to 24 hours; the mass ratio of alkaline cerium carbonate to sodium hydroxide solid is 1:15 to 1:16; the hydrothermal reaction temperature is 115 to 125°C, and the time is 20 to 24 hours.

[0016] Optionally, in step (2), the mass ratio of silver nitrate to cerium dioxide nanorods is 1-1.5:10; the pH value is adjusted to 7-8; the mass ratio of L-ascorbic acid to silver nitrate is 0.8-1:1; the drying temperature is 90-110° C., and the drying time is 20-26 hours.

[0017] The third object of the present invention is to provide an application of the silver-cerium dioxide composite nanorod material prepared by the method as described above in the rapid analysis and detection of trace organic matter.

[0018] Furthermore, the silver-cerium dioxide composite nanorod material is used in surface Raman enhanced spectroscopy.

[0019] Specifically, the silver-cerium dioxide composite nanorod material is used for detecting methylene blue and crystal violet in surface Raman enhanced spectroscopy testing.

[0020] It should be noted that the present invention successfully prepared the silver-cerium dioxide composite nanorod-like material according to the preparation scheme of the silver-cerium dioxide composite nanorod-like material proposed. Characterization methods such as HRTEM, XRD, XPS, and repeated experiments have proved that the preparation method in the solution can successfully prepare the silver-cerium dioxide composite nanorod-like material. It was used as a SERS substrate to test its detection effect on organic solutions of different concentrations, and the detection limit of methylene blue (MB) reached 10 - 11 M, the enhancement factor is 2.9×10 8 ; The detection limit of crystal violet (CV) reached 10 -8 M, the enhancement factor is 7.05×10 4 The above results show that the silver-cerium dioxide composite nanorod material has excellent SERS performance as a Raman substrate and can be used for Raman detection of organic matter.

[0021] Moreover, methylene blue and crystal violet were used as probe molecules to test the Raman enhancement effect of silver-cerium dioxide composite nanorods as Raman substrates. The results showed that the detection limit of methylene blue by the synthesized composite nanorods as Raman substrates reached 10 -11 M, the detection limit of crystal violet reached 10 -8 M, has excellent Raman enhancement performance.

[0022] The silver-cerium dioxide composite nanorod material prepared by the present invention has excellent detection capabilities for methylene blue and crystal violet in surface Raman enhanced spectroscopy testing and can achieve a lower detection limit, so the present invention can be used for rapid analysis and detection of trace organic matter.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1) Since silver nanomaterials produce a strong local plasma resonance effect under visible light irradiation, which plays a major role in the Raman scattering electromagnetic field enhancement mechanism (EM), silver nanomaterials have excellent SERS performance as SERS substrates. However, silver nanomaterials have the disadvantages of easy aggregation, easy oxidation, and insufficient self-stability. When probe molecules are adsorbed on the surface of ceria nanomaterials, charge transfer (CT) will occur between the two, thereby causing chemical enhancement (CM), but the effect of chemical enhancement is only 10 to 100 times. According to experiments, pure ceria nanorods have a very weak enhancement effect on organic methylene blue and crystal violet, and basically no signal can be observed. The composite nanostructure can combine the two Raman enhancement mechanisms and has better Raman performance. Therefore, the present invention creatively uses sodium hydroxide and L-ascorbic acid to combine silver nanoparticles with ceria nanorods. The silver-ceria composite nanorod-shaped material combines the electromagnetic enhancement mechanism of silver nanoparticles and the chemical enhancement mechanism of ceria, and acts on the Raman signal together to produce a better Raman signal.

[0025] 2) According to the preparation scheme of silver-cerium dioxide composite nanorod-like material proposed in the present invention, silver-cerium dioxide composite nanorod-like material was successfully prepared. Through characterization methods such as HRTEM, XRD, XPS and multiple repeated experiments, it was proved that the preparation method of the present invention can successfully prepare silver-cerium dioxide composite nanorod-like material.

[0026] 3) The silver-cerium dioxide composite nanorod material prepared by the present invention was used as a SERS substrate to detect methylene blue and crystal violet solutions of different concentrations. The minimum detection limit of methylene blue (MB) reached 10 -11 M, the maximum enhancement factor is 2.9×10 8 ; The minimum detection limit for crystal violet (CV) reached 10 -8 M, the maximum enhancement factor can reach 7.05×10 4 The above results show that the silver-cerium dioxide composite nanorod material as a Raman substrate has excellent SERS performance and can be used for Raman detection of organic matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0028] Figure 1 It is a schematic structural diagram of the silver-cerium dioxide composite nanorod material of the present invention.

[0029] Figure 2 It is a HRTEM image of the silver-cerium dioxide composite nanorod material described in the present invention.

[0030] Figure 3 This is the EDS mapping spectrum of the silver-cerium dioxide composite nanorod material described in the present invention.

[0031] Figure 4 It is the XRD spectrum of the silver-cerium dioxide composite nanorod material described in the present invention.

[0032] Figure 5 It is the XPS spectrum of the silver-cerium dioxide composite nanorod material described in the present invention.

[0033] Figure 6 The MB and CV Raman spectra of the silver-ceria composite nanorod material of the present invention are shown.

[0034] Figure 7 Methylene blue (MB) was used to test the analytical detection performance of pure cerium dioxide nanorod material as a Raman detection substrate material for organic matter. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The word "embodiment" used here as an "exemplary" does not necessarily mean that any embodiment described is superior to or better than other embodiments. Unless otherwise specified, the performance index tests in the embodiments of this application are performed using conventional test methods in the art. It should be understood that the terms described in this application are only used to describe specific implementation methods and are not used to limit the content disclosed in this application.

[0037] Unless otherwise specified, the technical and scientific terms used in this document have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs; other experimental methods and technical means not specifically specified in this application refer to experimental methods and technical means commonly used by ordinary technicians in this field.

[0038] In order to better illustrate the content of the present application, numerous specific details are provided in the specific examples below. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In the embodiments, some methods, means, instruments, equipment, etc. well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present application.

[0039] Under the premise of no conflict, the technical features disclosed in the embodiments of the present application can be combined arbitrarily, and the resulting technical solutions belong to the contents disclosed in the embodiments of the present application.

[0040] The invention discloses a silver-cerium dioxide composite nanorod material, a preparation method and application of the material in surface enhanced Raman spectroscopy.

[0041] In order to better understand the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as a limitation of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above invention content are also considered to fall within the protection scope of the present invention.

[0042] like Figure 1 As shown in the figure, the larger circle represents gold nanoparticles with a diameter of 20 to 50 nm, and the smaller circle with dots inside represents TiO 2 Nanoparticles, with a diameter of 5 to 20 nm. The small circle with a slash inside represents ZrO 2 Nanoparticles, with a diameter of 5 to 20 nm.

[0043] Example 1

[0044] (1) Weigh 1.75 g of cerium nitrate hexahydrate Ce(NO 3 ) 3 6H 2 O was dissolved in 80 mL of distilled water, and then 1.55 g of urea was weighed and slowly added to the solution under magnetic stirring; stirred for half an hour, and the resulting solution was colorless and transparent; the solution was poured into a round-bottom flask and stirred in an oil bath at 80 ° C for 24 hours. After the reaction, the solution was cooled to room temperature, washed with distilled water by centrifugation, and dried overnight to obtain white rod-shaped basic cerium carbonate Ce(OH)CO 3 ; Weigh 0.25g Ce(OH)CO 3 Add to 40mL distilled water, then add 3.85g NaOH solid, stir at room temperature for half an hour to obtain a milky white solution, then pour into a 50mL reactor and react in a 120℃ oven for 24h; after the reaction, wait for the reactor to cool to room temperature, centrifuge and wash with distilled water and ethanol in turn, dry at 100℃ for 24h to finally obtain CeO with a diameter of 400-600nm 2 Nanorods;

[0045] (2) Add 200 μL of 0.1 g / mL silver nitrate aqueous solution to 20 mL of deionized water, add 0.10 g of cerium dioxide nanorods, and stir vigorously for 1 hour to form a suspension; adjust the pH value of the suspension to 8 using 0.1 M sodium hydroxide solution, continue stirring for 30 minutes, centrifuge to separate the solid and liquid, then add 20 mL of 60 mM L-ascorbic acid solution, and observe that the color changes to black gray. Stir for 30 minutes, centrifuge, wash with deionized water and ethanol, and dry at 100° C. for 12 hours to obtain the silver-cerium dioxide composite nanorod material.

[0046] Example 2

[0047] (1) Weigh 1.70 g of cerium nitrate hexahydrate Ce(NO 3 ) 3 6H 2 O was dissolved in 80 mL of distilled water, and then 1.55 g of urea was weighed and slowly added to the solution under magnetic stirring; stirred for half an hour, and the resulting solution was colorless and transparent; the solution was poured into a round-bottom flask and stirred in an oil bath at 80 ° C for 24 hours. After the reaction, the solution was cooled to room temperature, washed with distilled water by centrifugation, and dried overnight to obtain white rod-shaped basic cerium carbonate Ce(OH)CO 3 ; Weigh 0.25g Ce(OH)CO 3 Add to 40mL distilled water, then add 3.90g NaOH solid, stir at room temperature for half an hour to obtain a milky white solution, then pour into a 50mL reactor and react in a 120℃ oven for 24h; after the reaction, wait for the reactor to cool to room temperature, centrifuge and wash with distilled water and ethanol in turn, dry at 100℃ for 24h to finally obtain CeO with a diameter of 400-600nm 2 Nanorods;

[0048] (2) Add 150 μL of 0.1 g / mL silver nitrate aqueous solution to 20 mL of deionized water, add 0.10 g of cerium dioxide nanorods, and stir vigorously for 1 hour to form a suspension; adjust the pH value of the suspension to 8 using 0.1 M sodium hydroxide solution, continue stirring for 30 minutes, centrifuge to separate the solid and liquid, then add 15 mL of 60 mM L-ascorbic acid solution, and observe that the color changes to black gray. Stir for 30 minutes, centrifuge, wash with deionized water and ethanol, and dry at 100° C. for 12 hours to obtain the silver-cerium dioxide composite nanorod material.

[0049] Example 3

[0050] (1) Weigh 1.78 g of cerium nitrate hexahydrate Ce(NO 3 ) 3 6H 2O was dissolved in 80 mL of distilled water, and then 1.58 g of urea was weighed and slowly added to the solution under magnetic stirring; stirred for half an hour, and the resulting solution was colorless and transparent; the solution was poured into a round-bottom flask and stirred in an oil bath at 80 ° C for 24 hours. After the reaction, the solution was cooled to room temperature, washed with distilled water by centrifugation, and dried overnight to obtain white rod-shaped basic cerium carbonate Ce(OH)CO 3 ; Weigh 0.25g Ce(OH)CO 3 Add to 40mL distilled water, then add 3.85g NaOH solid, stir at room temperature for half an hour to obtain a milky white solution, then pour into a 50mL reactor and react in a 120℃ oven for 24h; after the reaction, wait for the reactor to cool to room temperature, centrifuge and wash with distilled water and ethanol in turn, dry at 100℃ for 24h to finally obtain CeO with a diameter of 400-600nm 2 Nanorods;

[0051] (2) Add 200 μL of 0.1 g / mL silver nitrate aqueous solution to 20 mL of deionized water, add 0.10 g of cerium dioxide nanorods, and stir vigorously for 1 hour to form a suspension; adjust the pH value of the suspension to 7 using 0.1 M sodium hydroxide solution, continue stirring for 30 minutes, centrifuge to separate the solid and liquid, then add 20 mL of 60 mM L-ascorbic acid solution, and observe that the color changes to black gray. Stir for 30 minutes, centrifuge, wash with deionized water and ethanol, and dry at 100° C. for 12 hours to obtain the silver-cerium dioxide composite nanorod material.

[0052] In order to further demonstrate the beneficial effects of the present invention and to better understand the present invention, the following experiments are conducted to further illustrate / verify the technical features disclosed in the present invention.

[0053] 1. Use high-resolution transmission electron microscopy (HRTEM) and energy dispersive spectrometer (EDS) to analyze the surface morphology and composition of the samples

[0054] High-resolution transmission electron microscopy (HRTEM) was used to analyze the surface morphology of the samples. Figure 2 . Figure 2 a and Figure 2 CeO can be clearly seen in b 2 It is a solid rod-like structure, and the diameter of the nanorod is uniformly about 500nm. 2 A large number of round nanoparticles can be observed on the surface of the nanorods. They are Ag nanoparticles with a particle size of 20 to 50 nm ( Figure 2 c) in. Figure 2 The CeO 2The HRTEM results show that the silver-cerium dioxide composite nanorod material was successfully prepared using the preparation method in the solution, and the morphology and size are in line with expectations.

[0055] The elemental spectrum of silver-cerium dioxide composite nanorod material can be obtained by EDS mapping to determine the elemental composition, such as Figure 3 . Figure 3 a, b, c in the figure correspond to the EDS spectra of three elements, O, Ag, and Ce, respectively. The EDS results show that the sample is composed of three elements, O, Ce, and Ag, and are consistent with the electron microscopy results, proving that the sample is a silver-cerium dioxide composite nanorod material.

[0056] 2. Use X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS) to analyze the structure of the sample

[0057] The crystal structure of the silver-cerium dioxide composite nanorod material can be analyzed by X-ray diffractometer (XRD). Figure 4 As shown in the figure, the CeO is marked with black and blue lines in the lower half of the figure. 2 The peaks corresponding to the standard card (JCPDS: 43-1002) and the Ag standard card (JCPDS: 04-0783) can be seen in the figure. The peaks correspond to each other, and no other diffraction peaks appear in the figure, indicating that the sample is a pure silver-cerium dioxide composite nanorod material.

[0058] Silver-Cerium Oxide Composite Nanorods The surface composition and element valence of the composite nanorods can be analyzed by XPS results. Figure 5 The results obtained from the XPS test were analyzed by peak fitting using Advantage software, and the charge calibration was performed using the C1s peak position at 284.8 eV. Figure 5 a in the formula is Ag / CeO 2 The full XPS spectrum of the composite nanorods shows that the sample is mainly composed of Ce, O, and Ag elements. Figure 5 b is the fine spectrum of Ce 3d. The Ce element has Ce through peak fitting. 3+ 、Ce 4 + Two valence states. The fine spectrum of Ag 3d is shown in Figure 5 As shown in c, according to the fitting results, the characteristic peaks of Ag all correspond to the characteristic peaks of metal Ag, indicating that CeO 2 The Ag loaded on the surface of the nanorods exists in the form of metallic silver.

[0059] 3. Use probe molecules methylene blue (MB) and crystal violet (CV) to test Au-TiO2 / ZrO2 2 / ZrO 2 )Composite nanorod-like materials as Raman detection substrate materials for the analysis and detection of organic matter

[0060] Using commonly used probe molecules: methylene blue (MB) and crystal violet (CV), the performance of silver-cerium dioxide composite nanorods as Raman detection substrate materials for the analysis and detection of organic matter was tested. The results are as follows Figure 6 . Figure 6 a and b in the figure are the Raman spectra of MB. The detection limit of MB by silver-cerium dioxide composite nanorods is 10 -11 M. Figure 6 The c in the figure is the Raman spectrum for detecting CV, and the detection limit of CV is 10 -8 The above conclusions show that the silver-cerium dioxide composite nanorod material has excellent surface enhanced Raman performance as a Raman substrate.

[0061] 4 Using the probe molecule methylene blue (MB) to test the analytical detection performance of pure cerium dioxide nanorods as Raman detection substrate materials for organic matter

[0062] The commonly used probe molecule: methylene blue (MB) was used to test the analytical detection performance of pure cerium dioxide nanorods as Raman detection substrate materials for organic matter. The results are as follows Figure 7 . Figure 7 There is no characteristic peak of methylene blue and the noise signal is very strong.

[0063] The above conclusions indicate that pure ceria nanorods as Raman substrates have basically no surface enhanced Raman performance, proving that silver-ceria composite nanorods improve the Raman performance of ceria.

[0064] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A silver-cerium dioxide composite nanorod material, characterized in that: The composite nanorod material is composed of silver nanoparticles and cerium dioxide nanorods. The silver nanoparticles are loaded on the surface of the cerium dioxide nanorods. The atomic ratio of silver to cerium dioxide is 1:

10. The diameter of the cerium dioxide nanorods is 400-600nm, and the particle size of the silver nanoparticles is 20-50nm.

2. A method for preparing the silver-cerium dioxide composite nanorod material as claimed in claim 1, characterized in that: The method specifically comprises the following steps: (1) Preparation of cerium dioxide nanorods: Weigh hexahydrate cerium nitrate Ce(NO3)3·6H2O and dissolve it in distilled water, then weigh urea and slowly add it to the solution under magnetic stirring; stir for half an hour, and the resulting solution is colorless and transparent; pour the solution into a round-bottom flask, stir in an oil bath, and after the reaction, cool the solution to room temperature, wash it with distilled water by centrifugation, and dry it overnight to obtain white rod-shaped alkaline cerium carbonate Ce(OH)CO3; weigh Ce(OH)CO3 and add it to distilled water, then add NaOH solid, stir for half an hour at room temperature to obtain a milky white solution, then pour it into a reactor, and perform a hydrothermal reaction in an oven; after the reaction is completed, wait for the reactor to cool to room temperature, centrifuge it with a centrifuge, wash it with distilled water and ethanol in turn, and finally obtain CeO2 nanorods with a diameter of 400 to 600 nm after drying; (2) Loading silver nanoparticles: Add silver nitrate aqueous solution to ionized water, add the CeO2 nanorods prepared in step (1), and stir vigorously to form a suspension; The pH value of the suspension is adjusted with sodium hydroxide solution, and after continued stirring, the suspension is centrifuged to separate the solid and liquid, and then L-ascorbic acid solution is added, and the color can be observed to change to black gray. The suspension is stirred, centrifuged, washed with deionized water and ethanol, and dried to obtain the silver-cerium dioxide composite nanorod material.

3. The method for preparing the silver-cerium dioxide composite nanorod material according to claim 2, characterized in that: In step (1), the mass ratio of the cerium nitrate hexahydrate to urea is 0.9:2-1:2; the oil bath stirring reaction temperature is 70-90°C, and the time is 20-24h; the mass ratio of the basic cerium carbonate to the sodium hydroxide solid is 1:15-1:16; the hydrothermal reaction temperature is 115-125°C, and the time is 20-24h.

4. The method for preparing the silver-cerium dioxide composite nanorod material according to claim 2, characterized in that: In step (2), the mass ratio of silver nitrate to cerium dioxide nanorods is 1-1.5:10; the pH value is adjusted to 7-8; the mass ratio of L-ascorbic acid to silver nitrate is 0.8-1:1; the drying temperature is 90-110° C., and the drying time is 20-26 hours.

5. Use of the silver-cerium dioxide composite nanorod-shaped material as claimed in claim 1 or the silver-cerium dioxide composite nanorod-shaped material prepared by the method as claimed in claim 2 in the rapid analysis and detection of trace organic matter.

6. The use according to claim 5, characterized in that: The silver-cerium dioxide composite nanorod material is used in surface Raman enhanced spectroscopy.

7. The use according to claim 6, characterized in that: The silver-cerium dioxide composite nanorod material is used for detecting methylene blue and crystal violet in surface Raman enhanced spectroscopy testing.

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