A tungsten-containing monatomic oxide, preparation and use on metal nano-surfaces

Abstract

The application discloses tungsten monatomic oxide, preparation and application on metal nano surface, relates to the technical field of surface and interface chemistry. The tungsten monatomic oxide takes tungsten as a core metal monatomic atom, contains coexisting W 5+ and W 6+ ions, and the tungsten source is derived from specific tungstate or tungsten-containing metal oxide, can form hydrogen bonds with substances containing CH2CH2OH functional groups and promote the bonding of itself with a metal surface. The method comprises monatomic precursor liquid preparation, tungsten silver sol preparation and product fixing, and through the regulation of parameters such as solvent ratio and pH value, a SERS substrate with uniform array structure can be obtained through simple light irradiation and physical deposition process, and the film thickness can be flexibly regulated. The tungsten monatomic oxide is loaded on the surface of a metal nanoparticle modified silicon substrate, and a SERS detection substrate is constructed, and under a specific excitation wavelength, the Raman scattering signal can be enhanced through electron transfer. The application has simple process, convenient operation, is suitable for portable detection equipment, and has wide practical value and popularization prospect.

Description

Technical Field

[0001] This invention relates to the field of surface and interface chemistry, specifically to a tungsten single-atom oxide, its preparation method, and its application on the surface of metal nanoparticles. Background Technology

[0002] Surface-enhanced Raman scattering (SERS) technology, with its high sensitivity and fingerprint-like characteristics, has shown broad application prospects in environmental monitoring, food safety, and biochemical analysis. Its enhancement mechanisms are mainly divided into two categories: electromagnetic enhancement and chemical enhancement. Electromagnetic enhancement relies on the surface plasmon resonance effect of metal nanoparticles to amplify the signal, while chemical enhancement improves detection sensitivity through chemical interactions such as charge transfer between molecules and metals. In recent years, organic-inorganic composite materials have become a research hotspot in this field because they can undergo functional changes in response to external stimuli, and SERS performance can be optimized by controlling charge transfer efficiency, providing a new direction for solving the problem of insufficient sensitivity in traditional detection techniques.

[0003] In SERS chemical enhancement systems, single-atom metallic materials, due to their unique electronic structure and high atomic utilization, become key carriers for improving charge transfer efficiency. Tungsten metal single atoms, with their special electron orbital distribution, possess excellent electron-accepting capabilities, and their oxides contain W... 5 ⁺ ions and W 6 The coexistence of ⁺ ions at different energy levels allows for precise matching with the target molecular orbital energy levels. Under laser excitation, this promotes electron transfer between molecules and metals, thereby altering molecular energy levels and enhancing Raman signals. Therefore, it has attracted much attention in the development of SERS substrate materials.

[0004] Existing tungsten metal oxides and their salts still face significant bottlenecks in SERS signal enhancement applications. On the one hand, the enhancement efficiency is limited, with most materials achieving an SERS enhancement factor of only about 10², which is insufficient to meet the high sensitivity requirements for low-concentration target molecules in practical detection. On the other hand, the material preparation process is complex and has poor repeatability, resulting in insufficient uniformity of the enhancement factor. Significant differences in SERS signals exist between different detection points, severely affecting the reliability of detection results and restricting their large-scale application.

[0005] Besides issues with enhancement efficiency and reproducibility, the long-term stability and storage performance of existing tungsten-based composite materials also urgently need improvement. Some substrate materials are prone to structural changes under laser irradiation, temperature variations, or specific chemical environments, leading to a decline in SERS enhancement performance and hindering long-term storage and reuse, significantly limiting their application scope. Furthermore, existing preparation processes often require complex equipment and stringent reaction conditions, resulting in high instrument costs, cumbersome operating procedures, and poor compatibility with portable detection devices, making it difficult to meet the practical needs of rapid on-site detection.

[0006] To overcome the aforementioned technical bottlenecks, the development of tungsten-based SERS materials that combine high enhancement efficiency, good stability, and simple preparation processes has become an urgent industry need. Optimizing material composition and structure, controlling key parameters in the preparation process, and constructing organic-inorganic composite systems to enhance charge transfer effects, while simultaneously simplifying the preparation process and reducing costs, are core directions for improving the practical value of tungsten-based SERS materials and are of great significance for promoting the widespread application of SERS technology in various fields. Summary of the Invention

[0007] To address the aforementioned technical problems, this application discloses a tungsten-containing single-atom oxide, its preparation, and its application on metal nanosurfaces. The method for preparing the tungsten-containing single-atom oxide includes:

[0008] S1. Add deionized water to the container, then add tungsten source, stir magnetically until completely dissolved, then add ethylene glycol and 10% dilute sulfuric acid, and continue stirring until the solution is clear and transparent to obtain tungsten single-atom precursor solution;

[0009] S2. Add the composite solvent to the reaction flask, add the tungsten single-atom precursor solution prepared in S1 to the composite solvent at a volume ratio of less than 90%, then add silver nitrate solution, and then add acid and / or organic / inorganic substances containing acid groups to adjust the pH value of the system. After ultrasonic treatment, react under UV lamp with a light intensity of 65% until the solution shows a visible color change, and obtain tungsten silver sol containing tungsten single-atom oxide.

[0010] S3. The tungsten silver sol prepared in S2 is loaded onto the pretreated silicon substrate film and dried under specific temperature conditions to obtain a substrate material loaded with tungsten single-atom oxide.

[0011] The composite solvent is a mixture of water and an organic solvent, wherein the organic solvent is selected from at least one of ethanol, isopropanol, and acetone.

[0012] Preferably, in S1, the tungsten source is a tungstate or a tungsten-containing metal oxide; the tungstate is selected from at least one of ammonium tungstate, ammonium paratungstate, and ammonium metatungstate; the tungsten-containing metal oxide is selected from WO3 and WO4. 2.9 WO 2.72 WO 2.8 At least one of the following; the magnetic stirring time is based on the condition that the tungsten source is completely dissolved, and the solution is clear and free of precipitate after the addition of ethylene glycol and 10% dilute sulfuric acid.

[0013] Preferably, in S2, the mass percentage of the organic solvent in the composite solvent does not exceed 50%; among the acid and / or the organic / inorganic substances containing acid groups, the organic acid is selected from at least one of tartaric acid, ethylenediaminetetraacetic acid (EDTA), butanetetracarboxylic acid, oxalic acid, citric acid, benzenesulfonic acid, acrylic acid, polyacrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, and poly(2-acrylamide-2-methylpropanesulfonic acid), and the inorganic acid is selected from at least one of nitric acid, hydrochloric acid, and sulfuric acid; the pH value is adjusted to 1~6.

[0014] Preferably, in S2, the ultrasonic treatment time is 10s~30s; the UV lamp irradiation time is 300s~600s; and the color change of the solution is selected from clear and transparent to light gray, blue-gray or dark blue.

[0015] Preferably, in S3, the pretreatment process of the silicon-plated silicon film is as follows: the gold-plated silicon wafer is cut into a regular shape, ultrasonically cleaned with water and ethanol alternately 2 to 4 times, and then dried at 55℃ to 65℃; the side length of the regular-shaped gold-plated silicon wafer is 4mm to 6mm.

[0016] Preferably, in S3, the loading amount of the tungsten silver sol is 8. ~12 / piece; the drying temperature is 50℃~65℃, and the drying time is 3min~8min; during the drying process, it is necessary to ensure that the substrate surface is uniformly covered with sol to form an array structure; the loading method is physical deposition, including at least one of drop coating and spin coating.

[0017] One type is a tungsten single-atom oxide, which has tungsten as the core metallic single atom and contains coexisting W atoms located in two different energy levels. 5 ⁺ ions and W 6 ⁺ ions;

[0018] The tungsten source of the tungsten monatomic oxide is derived from tungstate or tungsten-containing metal oxide, wherein the tungstate is selected from at least one of ammonium tungstate, ammonium paratungstate, and ammonium metatungstate.

[0019] The tungsten-containing metal oxide is selected from WO3, WO4, and WO3. 2.9 WO 2.72 WO 2.8 At least one of them;

[0020] The tungsten single-atom oxide can form weak bonds with substances containing the -CH2CH2OH functional group through hydrogen bonding, thereby promoting its chemical bonding with the metal surface. Under laser excitation, it can undergo electron transfer with the target molecule to enhance the Raman scattering signal.

[0021] Preferably, the single-atom concentration of the tungsten single-atom oxide is 10. -2~10 -4 M, and can promote the self-assembly of gold / silver nanoparticles into aggregates under molecular action, thereby generating SERS hotspot effect; the substance containing the -CH2CH2OH functional group is ethylene glycol.

[0022] One application of tungsten single-atom oxide on the surface of metal nanoparticles is that tungsten single-atom oxide is loaded onto the surface of a silicon-based film modified with metal nanoparticles to construct a SERS detection substrate for enhanced detection of Raman scattering signals of target molecules.

[0023] The metal nanoparticles are gold nanoparticles or silver nanoparticles.

[0024] The target molecule is selected from at least one of rhodamine 6G and dimethyl methyl phosphate;

[0025] During detection, 785 nm was used as the excitation wavelength, the laser power was 40 mW~60 mW, the integration time was 3 s~5 s, and the integration was performed once. Qualitative or quantitative analysis was achieved by detecting the peak intensity at a specific Raman shift of the target molecule; among them, the characteristic Raman shift of Rhodamine 6G was 612 cm⁻¹. -1 The characteristic Raman shift of dimethyl methyl phosphate is 710 cm⁻¹. -1 The detection concentration of Rhodamine 6G was 10. -6 M, the detection concentration of the dimethyl methyl phosphate is 10. -3 ~10 -5 M.

[0026] Compared with the prior art, the technical solution of this application has the following technical effects:

[0027] This invention constructs a composite system containing tungsten single-atom oxide and gold / silver nanoparticles. By leveraging the unique electronic structure of tungsten single atoms and their hydrogen bonding with substances containing -CH2CH2OH functional groups, it significantly enhances the electron transfer efficiency between molecules and metals, greatly improving the SERS signal enhancement effect. This overcomes the limitation of insufficient enhancement ability of traditional tungsten-based materials, making it easier to capture the Raman scattering signal of target molecules and providing reliable support for the detection of low-concentration substances.

[0028] The preparation process of this invention has significant simplicity and operability. It does not require complex equipment or harsh reaction conditions. Material preparation and substrate construction can be completed through simple steps such as light irradiation and physical deposition. The simplification of the process not only reduces the investment in instruments and the difficulty of production, but also ensures the stability of product quality and helps to achieve large-scale production. At the same time, it has good compatibility with existing portable testing equipment, which broadens the application scenarios of the technology.

[0029] In the substrate construction process, the film thickness can be flexibly adjusted, and the tungsten-containing single-atom oxide can be uniformly distributed on the silicon-based film surface to form a regular array structure. The uniform composite structure not only facilitates the efficient adsorption of target molecules on the surface of metal nanoparticles, but also reduces the difference in SERS signal between different detection points, significantly improving the repeatability and reliability of the detection results, and laying a solid foundation for accurate quantitative analysis.

[0030] The composite substrate material prepared by this invention has good structural stability and is not prone to performance degradation under conventional detection and storage conditions. It can be stored and reused for a long time. At the same time, the material is suitable for the detection needs of various target molecules and the preparation cost is controllable. It reduces the overall cost of detection applications and meets the detection needs in different scenarios, thus having broad practical value and promotion prospects.

[0031] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the preferred embodiments of this application are described in detail below with reference to the accompanying drawings.

[0032] The above and other objects, advantages and features of this application will become more apparent to those skilled in the art from the following detailed description of specific embodiments in conjunction with the accompanying drawings. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0034] Based on the description of the figures and their corresponding technical content in the document, the titles of the figures are as follows:

[0035] Figure 1 This is a schematic diagram of the process steps of photodeposition of tungsten single-atom oxide onto gold / silver nanoparticles according to the present invention;

[0036] Figure 2 This is the SERS spectrum of tungsten silver sol for rhodamine 6G;

[0037] Figure 3 This is the SERS spectrum of dimethyl phosphate diluted with deionized water by silver sol.

[0038] Figure 4 This is the SERS spectrum of dimethyl methyl phosphate diluted with methanol as a solvent by silver sol. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. In the following description, specific details such as specific configurations and components are provided merely to help fully understand the embodiments of this application. Therefore, those skilled in the art should understand that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this application. In addition, for clarity and brevity, descriptions of known functions and structures are omitted in the embodiments.

[0040] It should be understood that the phrase "an embodiment" or "this embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of this application. Therefore, "an embodiment" or "this embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0041] Furthermore, reference numerals and / or letters may be repeated in different examples within this application. Such repetition is for the purpose of simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or settings discussed.

[0042] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist simultaneously. The term " / and" in this article describes another type of relationship between related objects, indicating that two relationships can exist. For example, A / and B can mean: A exists alone, and A and B exist alone. In addition, the character " / " in this article generally indicates that the related objects before and after it are in an "or" relationship.

[0043] In this article, the term "at least one" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, "at least one of A and B" can mean: A exists alone, A and B exist simultaneously, or B exists alone.

[0044] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion.

[0045] Example 1

[0046] This embodiment mainly describes a method for preparing a tungsten-containing single-atom oxide, such as... Figure 1 As shown in (a)-(d), the specific contents include:

[0047] Preparation of single-atom oxides;

[0048] Metal single atoms are loaded onto gold / silver nanoparticles, and metal sites are loaded onto gold / silver chips using physical deposition.

[0049] Rhodamine 6G and dimethyl methyl phosphate, among other analytes, were dropped onto a molecular site chip. The Raman peak intensities of Rhodamine 6G and dimethyl methyl phosphate at specific wavelengths were measured under optimal laser wavelength, integration time, and laser power. Raman scattering signal enhancement was achieved through electron transfer.

[0050] Furthermore, the preparation of single-atom oxides is specifically as follows:

[0051] S1. Add deionized water to the container, then add tungsten source, stir magnetically until completely dissolved, then add ethylene glycol and 10% dilute sulfuric acid, and continue stirring until the solution is clear and transparent to obtain tungsten single-atom precursor solution;

[0052] S2. Add the composite solvent to the reaction flask, add the tungsten single-atom precursor solution prepared in S1 to the composite solvent at a volume ratio of less than 90%, then add silver nitrate solution, and then add acid and / or organic / inorganic substances containing acid groups to adjust the pH value of the system. After ultrasonic treatment, react under UV lamp with a light intensity of 65% until the solution shows a visible color change, and obtain tungsten silver sol containing tungsten single-atom oxide.

[0053] S3. The tungsten silver sol prepared in S2 is loaded onto the pretreated silicon substrate film and dried under specific temperature conditions to obtain a substrate material loaded with tungsten single-atom oxide.

[0054] The composite solvent is a mixture of water and an organic solvent, wherein the organic solvent is selected from at least one of ethanol, isopropanol, and acetone.

[0055] Further, in S1, the tungsten source is a tungstate or a tungsten-containing metal oxide; the tungstate is selected from at least one of ammonium tungstate, ammonium paratungstate, and ammonium metatungstate; the tungsten-containing metal oxide is selected from WO3 and WO4. 2.9 WO 2.72 WO 2.8 At least one of the following; the magnetic stirring time is based on the condition that the tungsten source is completely dissolved, and the solution is clear and free of precipitate after the addition of ethylene glycol and 10% dilute sulfuric acid.

[0056] Further, in S2, the mass percentage of the organic solvent in the composite solvent does not exceed 50%; among the acids and / or organic / inorganic substances containing acid groups, the organic acid is selected from at least one of tartaric acid, ethylenediaminetetraacetic acid (EDTA), butanetetracarboxylic acid, oxalic acid, citric acid, benzenesulfonic acid, acrylic acid, polyacrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, and poly(2-acrylamide-2-methylpropanesulfonic acid), and the inorganic acid is selected from at least one of nitric acid, hydrochloric acid, and sulfuric acid; the pH value is adjusted to 1~6.

[0057] Furthermore, in S2, the ultrasonic treatment time is 10s~30s; the UV lamp irradiation time is 300s~600s; and the color change of the solution is selected from clear and transparent to light gray, blue-gray or dark blue.

[0058] Furthermore, in S3, the pretreatment process of the silicon-plated silicon film is as follows: the gold-plated silicon wafer is cut into a regular shape, ultrasonically cleaned with water and ethanol alternately 2 to 4 times, and then dried at 55℃ to 65℃; the side length of the regular-shaped gold-plated silicon wafer is 4mm to 6mm.

[0059] Furthermore, in S3, the loading amount of the tungsten-silver sol is 8. ~12 / piece; the drying temperature is 50℃~65℃, and the drying time is 3min~8min; during the drying process, it is necessary to ensure that the substrate surface is uniformly covered with sol to form an array structure; the loading method is physical deposition, including at least one of drop coating and spin coating.

[0060] The tungsten single-atom oxide is loaded onto the surface of a silicon-based film modified with metal nanoparticles to construct a SERS detection substrate for enhanced detection of Raman scattering signals of target molecules.

[0061] The metal nanoparticles are gold nanoparticles or silver nanoparticles.

[0062] The target molecule is selected from at least one of rhodamine 6G and dimethyl methyl phosphate;

[0063] During detection, 785 nm was used as the excitation wavelength, the laser power was 40 mW~60 mW, the integration time was 3 s~5 s, and the integration was performed once. Qualitative or quantitative analysis was achieved by detecting the peak intensity at a specific Raman shift of the target molecule; among them, the characteristic Raman shift of Rhodamine 6G was 612 cm⁻¹. -1 The characteristic Raman shift of dimethyl methyl phosphate is 710 cm⁻¹. -1 The detection concentration of Rhodamine 6G was 10. -6 M, the detection concentration of the dimethyl methyl phosphate is 10. -3 ~10 -5 M.

[0064] The implementation details how the interaction between tungsten-containing metal oxides and / or tungstates and the -CH2CH2OH functional group leads to changes in molecular energy levels, an increase in the density of electronic states due to hydrogen bonding, enhanced electron transfer, and consequently, a stronger Raman signal.

[0065] Example 2 details the photodeposition process of tungsten single-atom oxide onto gold / silver nanoparticles, such as... Figure 1 As shown, specifically:

[0066] Preparation of tungsten single-atom oxide: Add 20 ml of deionized water to a reaction flask, then add 0.55 g of sodium tungstate, stir magnetically until completely dissolved, add 300 μl of ethylene glycol and 1 ml of 10% dilute sulfuric acid, and wait for it to dissolve and clarify before use to obtain tungsten single-atom solution.

[0067] Preparation method of tungsten-silver sol: Place 100 ml of solvent in a reaction flask, add tungsten single-atom solution to the solvent at a volume ratio of less than 90%, add silver nitrate solution, and adjust the pH to 1-6 by adding acid and / or organic / inorganic substances containing acid groups to ensure the functionality of the solution. Sonicate for 10 seconds. Under 65% UV light irradiation for 600 seconds, the prepared solution will show a visible color change, changing from clear and transparent to bluish-gray.

[0068] Water and / or organic solvents are used as solvents. Acids or organic and inorganic acids with acid groups, such as weak acids like tartaric acid and EDTA, moderately strong acids like oxalic acid, citric acid, and benzenesulfonic acid, strong acids like sulfuric acid, hydrochloric acid, and nitric acid, and polymers with acid functional groups such as acrylic acid, polyacrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, and poly(2-acrylamido-2-methylpropanesulfonic acid), are added to the solution. Other solvents and dispersants added to the solution include, but are not limited to, ethanol, isopropanol, acetone, and water.

[0069] Gold / silver Ag substrate preparation method: Gold-plated silicon wafers cut into regular squares of 5mm × 5mm were ultrasonically cleaned three times alternately with water and ethanol, and then dried at 60℃. The sol prepared in Example 2 was dropped onto the gold-plated silicon wafers and dried at 50–65℃ for 5 minutes.

[0070] Based on Examples 1-2 above, by fixing the amount of silver nitrate, solvent type and UV lamp irradiation conditions, and only adjusting the amount of tungsten single-atom solution added, the effect of different single-atom concentrations on the appearance of the sol was verified, as shown in Examples 3-8.

[0071] Example 3: In this example, 10 ml of deionized water was added to a reaction flask, and 200 μl of silver nitrate was added to 200 μl of tungsten solution. The mixture was stirred magnetically until completely dissolved. Judgment criterion: Under 65% UV light irradiation, a visible color change was observed within 600 seconds, changing from clear and transparent to light gray.

[0072] Example 4: Add 10 ml of deionized water to a reaction flask, add 200 μl of silver nitrate to 400 μl of tungsten solution, and stir magnetically until completely dissolved. Judgment criterion: Under 65% UV light irradiation for 600 seconds, a visible color change will occur, from clear and transparent to bluish-gray.

[0073] Example 5: Add 10 ml of deionized water to a reaction flask, add 200 μl of silver nitrate to 600 μl of tungsten solution, and stir magnetically until completely dissolved. Judgment criterion: Under 65% UV light irradiation, a visible color change will occur within 600 seconds, changing from clear and transparent to bluish-gray.

[0074] Example 6: 10 ml of deionized water was added to a reaction flask, and 800 μl of tungsten solution was added to 200 μl of silver nitrate. The mixture was stirred magnetically until completely dissolved. Judgment criterion: Under 65% UV light irradiation, a visible color change was observed within 600 seconds, changing from clear and transparent to deep blue.

[0075] Example 7: 10 ml of deionized water was added to a reaction flask, and 1000 μl of tungsten solution was added to 200 μl of silver nitrate. The mixture was stirred magnetically until completely dissolved. Judgment criterion: Under 65% UV light irradiation, a visible color change was observed within 600 seconds, from clear and transparent to deep blue.

[0076] Example 8: Add 10 ml of deionized water to a reaction flask, add 200 μl of silver nitrate to 1200 μl of tungsten solution, and stir magnetically until completely dissolved. Judgment criterion: Under 65% UV light irradiation, a visible color change will occur within 600 seconds, changing from clear and transparent to deep blue.

[0077] Based on Examples 3-8 above, it can be seen that as the amount of tungsten single-atom solution added gradually increases from 200 μl to 1200 μl, the sol color exhibits a regular change within 600 seconds of UV lamp irradiation at 65% intensity: from light gray at 200 μl, to bluish-gray at 400 μl and 600 μl, and then to deep blue at 800 μl and above. This color gradient change intuitively reflects the gradual enhancement of the interaction strength and electron transfer effect between tungsten single atoms and silver ions. Moreover, when the amount added is ≥800 μl, the sol color depth tends to stabilize, indicating that the concentration of tungsten single atoms in the system can fully combine with silver ions to form a stable composite structure, providing a reliable material basis for subsequent SERS signal enhancement.

[0078] Based on Examples 1-2 above, using the SERS substrate prepared in Example 2, the detection performance of the technical solution was verified by detecting Rhodamine 6G and dimethyl methyl phosphate diluted with different solvents, as shown in Examples 9-11.

[0079] Example 9, Method of using the colloid and detection of Rhodamine 6G: Take the Rhodamine 6G standard solution and dilute it to 10 with deionized water as the solvent. -6 The Raman spectrometer parameters were set as follows: excitation wavelength 785 nm, laser power 50 mW, integration times 1, integration time 3-5 s. A silicon wafer was used to calibrate the Raman spectrometer; the characteristic peak shift on the silicon wafer was 520.6 cm⁻¹. -1 The Raman peak intensity of the silicon wafer was 5000. The prepared chip was then placed under a Raman spectrometer. The video screen was observed, the focus was adjusted, and 10 μl of diluted Rhodamine 6G was dropped onto the chip using a pipette. After natural drying, continuous spectral acquisition was initiated, and the 612 cm⁻¹ peak intensity was observed. -1 714 cm -1 The peak value at that location changes.

[0080] like Figure 2 The image shows the SERS spectrum of single-atom pairs of Rhodamine 6G. Under 65% UV light intensity, the colloid exhibits a significant color change visible to the naked eye within 10 minutes, indicating strong electron transfer. The intensity of the characteristic peak in the Raman transmission spectrum increases with the addition of tungsten single-atom oxide, with the best enhancement effect observed at an addition of 1200 μL, reaching 774 cm⁻¹. -1 Peak strength increased by nearly 10 3 times.

[0081] Example 10, SERS detection of dimethyl methyl phosphate: Dimethyl methyl phosphate solutions of different concentrations were prepared. A standard solution of dimethyl methyl phosphate was prepared using deionized water as the solvent, with a concentration of 10... -3~10 -5 The Raman spectrometer parameters were set as follows: excitation wavelength 785 nm, laser power 50 mW, integration times 1, integration time 3-5 s. A silicon wafer was used to calibrate the Raman spectrometer; the characteristic peak shift on the silicon wafer was 520.6 cm⁻¹. -1 The Raman peak intensity of the silicon wafer was 5000. The prepared chip was then placed under a Raman spectrometer. The video screen was observed, the focus was adjusted, and 10 μl of diluted dimethyl methyl phosphate was dropped onto the chip using a pipette. After natural drying, continuous spectral acquisition was initiated, and the 710 cm⁻¹ peak intensity was observed. -1 Peak variation at; such as Figure 3 As shown, the SERS spectrum of a dimethyl methyl phosphate solution diluted with deionized water is presented.

[0082] Example 11, SERS detection of dimethyl methyl phosphate: Dimethyl methyl phosphate solutions of different concentrations were prepared. A standard solution of dimethyl methyl phosphate was prepared using methanol as the solvent, with a concentration of 10... -3 ~10 -5 The Raman spectrometer parameters were set as follows: excitation wavelength 785 nm, laser power 50 mW, integration times 1, integration time 3-5 s. A silicon wafer was used to calibrate the Raman spectrometer; the characteristic peak shift on the silicon wafer was 520.6 cm⁻¹. -1 The Raman peak intensity of the silicon wafer was 5000. The prepared chip was then placed under a Raman spectrometer. The video screen was observed, the focus was adjusted, and 10 μl of diluted dimethyl methyl phosphate was dropped onto the chip using a pipette. After natural drying, continuous spectral acquisition was initiated, and the 710 cm⁻¹ peak intensity was observed. -1 Peak variation at; such as Figure 4 As shown, the SERS spectrum of a methanol-dimethyl methyl phosphate solution is presented.

[0083] Based on Examples 9-11 above, it can be seen that under the detection conditions of 785nm excitation wavelength, 50mW laser power, and 3-5s integration time, the prepared SERS chip exhibits excellent detection performance for target molecules: for 10 -6 A 6g Rhodamine solution with concentration M has a 612cm⁻¹ chromatogram. -1 714cm -1 The characteristic peaks at the location are clearly distinguishable, and the peak intensity increases significantly with increasing tungsten single-atom addition, with the best enhancement effect observed at an addition amount of 1200 μl; for 10 -3 ~10 -5 Solutions of dimethyl methyl phosphate with concentrations in the M range, using deionized water and methanol as solvents respectively, can all be expressed at 710 cm⁻¹. -1Stable characteristic peaks were detected, and the peak intensity showed a clear regularity with the concentration. There were no significant interference from other peaks, proving that the chip can achieve highly sensitive qualitative and quantitative analysis of target molecules in different solvent systems and at different concentrations, and the detection repeatability is good.

[0084] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any changes, modifications, substitutions, integrations, and parameter changes made to these embodiments within the spirit and principles of the present invention, without departing from the principles and spirit of the present invention, through conventional substitutions or to achieve the same function, fall within the scope of protection of the present invention.

Claims

1. A method for preparing a tungsten-containing single-atom oxide, characterized in that, Includes the following steps: S1. Add deionized water to the container, then add tungsten source, stir magnetically until completely dissolved, then add ethylene glycol and 10% dilute sulfuric acid, and continue stirring until the solution is clear and transparent to obtain tungsten single-atom precursor solution; S2. Add the composite solvent to the reaction flask, add the tungsten single-atom precursor solution prepared in S1 to the composite solvent at a volume ratio of less than 90%, then add silver nitrate solution, and then add acid and / or organic / inorganic substances containing acid groups to adjust the pH value of the system. After ultrasonic treatment, react under UV lamp with a light intensity of 65% until the solution shows a visible color change, and obtain tungsten silver sol containing tungsten single-atom oxide. S3. The tungsten silver sol prepared in S2 is loaded onto the pretreated silicon substrate film and dried under specific temperature conditions to obtain a substrate material loaded with tungsten single-atom oxide. The composite solvent is a mixture of water and an organic solvent, wherein the organic solvent is selected from at least one of ethanol, isopropanol, and acetone.

2. The method for preparing tungsten-containing single-atom oxide according to claim 1, characterized in that, In S1, the tungsten source is a tungstate or a tungsten-containing metal oxide; the tungstate is selected from at least one of ammonium tungstate, ammonium paratungstate, and ammonium metatungstate; the tungsten-containing metal oxide is selected from WO3 and WO4. 2.9 WO 2.72 WO 2.8 At least one of the following; the magnetic stirring time is based on the condition that the tungsten source is completely dissolved, and the solution is clear and free of precipitate after the addition of ethylene glycol and 10% dilute sulfuric acid.

3. The method for preparing tungsten-containing single-atom oxide according to claim 2, characterized in that, In S2, the organic solvent accounts for no more than 50% of the total mass of the composite solvent; among the acids and / or organic / inorganic substances containing acid groups, the organic acid is selected from at least one of tartaric acid, ethylenediaminetetraacetic acid (EDTA), butanetetracarboxylic acid, oxalic acid, citric acid, benzenesulfonic acid, acrylic acid, polyacrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, and poly(2-acrylamide-2-methylpropanesulfonic acid), and the inorganic acid is selected from at least one of nitric acid, hydrochloric acid, and sulfuric acid; the pH value is adjusted to 1-6.

4. The method for preparing tungsten-containing single-atom oxide according to claim 3, characterized in that, In S2, the ultrasonic treatment time is 10s~30s; the UV lamp irradiation time is 300s~600s; and the color change of the solution is selected from clear and transparent to light gray, blue-gray or dark blue.

5. The method for preparing tungsten-containing single-atom oxide according to claim 1, characterized in that, In S3, the pretreatment process of the silicon-plated silicon film is as follows: the gold-plated silicon wafer is cut into a regular shape, ultrasonically cleaned with water and ethanol alternately 2 to 4 times, and then dried at 55℃ to 65℃; the side length of the regular-shaped gold-plated silicon wafer is 4mm to 6mm.

6. The method for preparing tungsten-containing single-atom oxide according to claim 5, characterized in that, In S3, the loading of the tungsten silver sol is 8. ~12 / piece; the drying temperature is 50℃~65℃, and the drying time is 3min~8min; during the drying process, it is necessary to ensure that the substrate surface is uniformly covered with sol to form an array structure; the loading method is physical deposition, including at least one of drop coating and spin coating.

7. A tungsten single-atom oxide, characterized in that, The tungsten single-atom oxide has tungsten as the core metallic single atom and contains coexisting W atoms located in two different energy levels. 5+ Ions and W 6+ ion; The tungsten source of the tungsten monatomic oxide is derived from tungstate or tungsten-containing metal oxide, wherein the tungstate is selected from at least one of ammonium tungstate, ammonium paratungstate, and ammonium metatungstate. The tungsten-containing metal oxide is selected from WO3, WO4, and WO3. 2.9 WO 2.72 WO 2.8 At least one of them; The tungsten single-atom oxide can form weak bonds with substances containing the -CH2CH2OH functional group through hydrogen bonding, thereby promoting its chemical bonding with the metal surface. Under laser excitation, it can undergo electron transfer with the target molecule to enhance the Raman scattering signal.

8. A tungsten single-atom oxide according to claim 1, characterized in that, The single-atom concentration of the tungsten single-atom oxide is 10. -2 ~10 -4 M, and can promote the self-assembly of gold / silver nanoparticles into aggregates under molecular action, thereby generating SERS hotspot effect; the substance containing the -CH2CH2OH functional group is ethylene glycol.

9. The application of a tungsten single-atom oxide on the surface of metal nanoparticles, characterized in that, The tungsten single-atom oxide described in claims 7-8 is loaded onto the surface of a silicon-based film modified with metal nanoparticles to construct a SERS detection substrate for enhanced detection of Raman scattering signals of target molecules. The metal nanoparticles are gold nanoparticles or silver nanoparticles. The target molecule is selected from at least one of rhodamine 6G and dimethyl methyl phosphate; During detection, 785 nm was used as the excitation wavelength, the laser power was 40 mW~60 mW, the integration time was 3 s~5 s, and the integration was performed once. Qualitative or quantitative analysis was achieved by detecting the peak intensity at a specific Raman shift of the target molecule; among them, the characteristic Raman shift of Rhodamine 6G was 612 cm⁻¹. -1 The characteristic Raman shift of dimethyl methyl phosphate is 710 cm⁻¹; the detection concentration of rhodamine 6G is 10. -6 M, the detection concentration of the dimethyl methyl phosphate is 10. -3 ~10 -5 M.

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