A raman probe based on reduced graphene oxide enhanced semiconductor plasmon and a preparation method and application thereof

Abstract

The application belongs to the technical field of SERS detection, and particularly relates to a Raman probe based on reduced graphene oxide enhanced semiconductor plasmon and a preparation method and application thereof. The application utilizes a solvothermal method to prepare a composite structure of in-situ loaded reduced graphene oxide on semiconductor plasmon tungsten oxide nanowires, and uses the composite structure as a Raman probe to realize the dual functions of methylene blue (MB) molecule quantitative detection and photocatalytic degradation. WO 3‑x After being combined with reduced graphene oxide, on one hand, the probe can effectively adsorb target aromatic pollutant molecules through π-π stacking interaction, improve the SERS activity of the probe, on the other hand, the probe can effectively stabilize the surface oxygen vacancies of semiconductor WO 3‑x , promote the continuous generation of hot electrons, provide more reaction active sites, improve the photocatalytic degradation performance of the probe, and simultaneously use SERS in-situ monitoring to obtain the information of molecule chemical bond breaking priority.

Description

Technical Field

[0001] This invention belongs to the field of SERS detection technology, specifically relating to a Raman probe based on reduced graphene oxide enhanced semiconductor plasma, its preparation method, and its application. Background Technology

[0002] Trace detection and catalytic degradation of pollutant molecules are crucial for environmental protection. A deeper understanding of the mechanisms of pollutant catalytic degradation helps in exploring and developing new technological systems to improve degradation efficiency and further optimize environmental protection solutions. However, traditional pollutant detection methods suffer from bottlenecks such as low sensitivity, susceptibility to interference, and inability to perform in-situ detection.

[0003] Surface plasmon resonance (SPR) is a phenomenon where free electrons on the surface of noble metal nanostructures oscillate collectively under light irradiation. This localizes the light field and energy at the subwavelength scale, significantly enhancing various light-matter interactions (such as Raman scattering and photochemical reactions). Currently, various noble metal nanostructures have been developed as emerging Raman probes for ultrasensitive surface-enhanced Raman scattering (SERS) sensing of biochemical molecules. However, the high cost and high price of noble metal Raman probes hinder their large-scale application. Research has found that, in addition to noble metals, semiconductors also exhibit SPR-like phenomena when the free carrier concentration increases to a certain level, oscillating with incident light. For example, self-doped semiconductors (Cu...)... 2-x S, WO 3-x Semiconductors exhibit strong SPR absorption over a wide range in the visible-near infrared band, and their abundant surface vacancies can provide active sites for chemical reactions, thus showing broad application prospects in SERS sensing, photocatalysis, and other fields. However, in single semiconductor material systems, the instability of oxygen vacancies and the rapid nonradiative decay of hot carriers severely limit their SERS detection and photocatalytic degradation performance. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, this invention proposes a Raman probe based on reduced graphene oxide enhanced semiconductor plasma, which utilizes a semiconductor with SPR effect (such as WO3). 3-x The Raman probe exhibits multiple physical effects with ultrathin two-dimensional material reduced graphene oxide (rGO), such as SPR local field enhancement, charge transfer, and molecular enrichment. This enables ultrasensitive SERS detection and efficient catalytic degradation of target molecules, allowing the Raman probe to be reused while simultaneously acquiring information on the priority of molecular chemical bond breaking through in-situ SERS monitoring.

[0005] To achieve the above objectives, the first aspect of the present invention provides a Raman probe for semiconductor plasma enhanced by reduced graphene oxide, wherein the Raman probe is a composite structure of reduced graphene oxide supported on semiconductor plasma tungsten oxide nanowires. This composite structure exhibits significant plasmon resonance absorption in the 500-1400 nm wavelength region. The diameter of the plasma tungsten oxide nanowires is 5-10 nm, the length is 100-400 nm, and the size of the reduced graphene oxide is 1-5 μm, and the thickness is 2-6 nm.

[0006] The second aspect of the present invention also provides a method for preparing the Raman probe of reduced graphene oxide enhanced semiconductor plasma as described in the first aspect, specifically: adding graphene oxide to an ethylene glycol solution of tungsten hexachloride, stirring to form a uniform solution, and then carrying out a solvothermal reaction; after the reaction, washing and drying are performed to prepare a reduced graphene oxide / plasma tungsten oxide composite structure.

[0007] Preferably, the concentration of tungsten hexachloride in the ethylene glycol solution is 2-10 mg / mL, and the mass ratio of tungsten hexachloride to graphene oxide is (50-150):1.

[0008] Preferably, the temperature of the solvothermal reaction is 160-200℃ and the time is 18-30h.

[0009] Preferably, the washing is performed by centrifugation with water and ethanol at a speed of 5000-9000 r / min for 5-15 min.

[0010] The third aspect of the present invention also provides the application of the Raman probe of the reduced graphene oxide enhanced semiconductor plasma described in the first aspect in the quantitative determination of methylene blue (MB) molecule concentration.

[0011] Research has shown that, targeting MB, the Raman probe based on reduced graphene oxide-enhanced semiconductor plasma provided by this invention has a detection concentration limit as low as 10. -10 moles per liter, for a concentration of 10 -6 The MB molecule of M can be efficiently catalyzed and degraded within 5 minutes, demonstrating ultrasensitive SERS detection capability and highly efficient catalytic degradation activity.

[0012] Preferably, the method for quantifying the concentration of methylene blue molecules includes the following steps:

[0013] S1. The Raman probe of reduced graphene oxide enhanced semiconductor plasma described in the first aspect is dispersed in an ethanol solution and then drop-coated onto a substrate and allowed to dry naturally.

[0014] S2. Immerse the substrate in methylene blue molecular solutions of different concentrations, and collect Raman spectra after adsorption for more than 30 minutes.

[0015] S3. Plot the characteristic Raman peak intensity of methylene blue as a function of concentration, complete the standard curve fitting, and then determine the concentration of the methylene blue molecule to be tested based on the standard curve.

[0016] More preferably, the concentration of the Raman probe for reducing graphene oxide-enhanced semiconductor plasma in the ethanol solution is 0.5-3 mg / mL.

[0017] More preferably, the methylene blue molecular solutions of different concentrations refer to 10 -10 M-10 -6 Methylene blue molecular solution.

[0018] More preferably, the excitation wavelength of the Raman spectrum is 633 nm and the power is 0.01-1 mW.

[0019] More preferably, the Raman probe for reducing graphene oxide-enhanced semiconductor plasma is dispersed in an ethanol solution by ultrasonic dispersion, with an ultrasonic power of 400-800W and a time of 1-10min.

[0020] The fourth aspect of the present invention also provides the application of the Raman probe for reducing graphene oxide-enhanced semiconductor plasma as described in the first aspect in in-situ Raman monitoring of photocatalytic degradation of methylene blue molecules.

[0021] This invention constructs a Raman probe based on reduced graphene oxide-enhanced semiconductor plasma (SPR) by in-situ growing a composite structure of plasma semiconductor on ultrathin two-dimensional material reduced graphene oxide (rGO). rGO exhibits a strong affinity for aromatic ring molecules through π-π stacking interactions, enabling effective enrichment of target aromatic pollutant molecules. Simultaneously, it stabilizes surface oxygen vacancies in the composite structure, promotes the generation of hot electrons, and provides more active sites, thereby improving the probe's photocatalytic degradation performance. Furthermore, during catalytic degradation, the Raman probe based on reduced graphene oxide-enhanced semiconductor plasma synergistically enhances the Raman signal of pollutant molecules through multiple physical effects such as SPR local field enhancement, charge transfer, and molecular enrichment. This allows for in-situ SERS monitoring of the molecular degradation process and acquisition of chemical bond breaking priority information. Therefore, the Raman probe based on reduced graphene oxide-enhanced semiconductor plasma proposed in this invention possesses the dual functions of quantitative SERS analysis of target molecules and self-tracking photocatalytic degradation, providing a new approach for a deeper understanding of the catalytic degradation mechanism of pollutants.

[0022] Preferably, the method for in-situ Raman monitoring of photocatalytic degradation of methylene blue molecules is as follows:

[0023] S1. The Raman probe of reduced graphene oxide enhanced semiconductor plasma described in the first aspect is dispersed in an ethanol solution and then drop-coated onto a substrate and allowed to dry naturally.

[0024] S2. Immerse the substrate in methylene blue molecular solutions of different concentrations. After adsorption for more than 30 minutes, irradiate the substrate with adsorbed methylene blue molecules with a xenon lamp. During this process, collect Raman spectra at the same position every 1 minute until the Raman signal of MB can no longer be detected.

[0025] S3. Plot the natural logarithm of the ratio of the characteristic peak Raman intensity of the methylene blue molecule to the initial Raman intensity at reaction time t as a function of reaction time. Determine the degradation rate constant of the chemical bond corresponding to the characteristic peak from the slope of the curve, and analyze the priority order of molecular chemical bond breaking.

[0026] More preferably, the xenon lamp has a spectral wavelength of 190-1100 nm and an irradiation power density of 100-300 mW·cm⁻¹. -2 .

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] This invention discloses a method for preparing reduced graphene oxide-enhanced semiconductor plasma. A composite structure of reduced graphene oxide supported in situ on tungsten oxide nanowires for semiconductor plasma is prepared via a solvothermal method, and used as a Raman probe to achieve both quantitative detection and photocatalytic degradation of methylene blue (MB) molecules. This invention utilizes semiconductors with SPR effects (such as WO3) 3-x When combined with the ultrathin two-dimensional material reduced graphene oxide (rGO), rGO can efficiently adsorb target aromatic pollutant molecules through π-π stacking interactions, thereby improving the SERS activity of the probe. Furthermore, rGO can effectively stabilize the semiconductor WO3. 3-x The probe utilizes surface oxygen vacancies to address the instability issues caused by the semiconductor SPR effect, promoting the continuous generation of hot electrons and providing more reactive sites to improve the photocatalytic degradation performance of the probe. Simultaneously, in-situ SERS monitoring is used to obtain information on the priority of molecular chemical bond breaking. This probe utilizes semiconductors with SPR effects (such as WO3) 3-x It can replace high-cost precious metals, effectively reduce the cost of probe preparation, and achieve integrated detection and degradation, which is expected to enable large-scale reuse. Attached Figure Description

[0029] Figure 1 Transmission electron microscope image of the reduced graphene oxide / plasma-induced tungsten oxide composite structure;

[0030] Figure 2Electron paramagnetic spectra of the reduced graphene oxide / plasma tungsten oxide composite structure;

[0031] Figure 3 To reduce the UV-Vis-NIR diffuse reflectance spectrum of the graphene oxide / plasma-induced tungsten oxide composite structure;

[0032] Figure 4 Linear fitting curve of the intensity of characteristic Raman peaks of MB molecules as a function of concentration for the detection of WO / rGO Raman probe;

[0033] Figure 5 A linear fitting curve of the ratio of Raman intensity to initial intensity of characteristic peak of MB molecule at time t and catalytic degradation time was obtained for in-situ monitoring using WO / rGO Raman probe. Detailed Implementation

[0034] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0036] Example 1: Preparation of a reduced graphene oxide enhanced semiconductor plasma

[0037] 150 mg of tungsten hexachloride powder was dissolved in 30 mL of ethylene glycol solution and stirred until the solution turned into a clear yellow liquid. Then, 0.75 mL of graphene oxide ethylene glycol solution (rGO, 2 mg / mL) was added to the above solution and stirred for 10 minutes to form a homogeneous solution. The resulting solution was then transferred to a 50 mL Teflon reactor and heated at 180 °C for 24 h. After cooling, it was centrifuged at 9000 r / min for 5 min and washed successively with deionized water and anhydrous ethanol. Finally, it was dried in a vacuum oven at 60 °C for 12 h to obtain a reduced graphene oxide / plasma tungsten oxide (WO / rGO) powder sample.

[0038] Figure 1The image shows a transmission electron microscope (TEM) image of a reduced graphene oxide / plasma-based tungsten oxide composite structure prepared by a solvothermal method. Plasma-based tungsten oxide nanowires with diameters of 5-10 nm and lengths of 100-400 nm are uniformly dispersed on an rGO layer with a thickness of 2-6 nm. Simultaneously, oxygen vacancy doping increases the free electron concentration on the surface of the plasma-based tungsten oxide, enabling it to exhibit SPR resonance absorption in the 500-1400 nm wavelength region. Furthermore, when combined with rGO, rGO stabilizes oxygen vacancies, thereby enhancing the SPR. Figure 2 Furthermore, the UV-Vis-NIR diffuse reflectance spectrum of the reduced graphene oxide / plasma-oxidized tungsten oxide composite structure also exhibits enhanced SPR resonance absorption intensity, such as... Figure 3 As shown.

[0039] Example 2: Quantification of methylene blue (MB) molecule concentration and photocatalytic degradation of methylene blue molecules using reduced graphene oxide-enhanced semiconductor plasma as a Raman probe (WO / rGO Raman probe).

[0040] The reduced graphene oxide / plasma-oxidized tungsten oxide powder sample prepared in Example 1 was ultrasonically dispersed in anhydrous ethanol solution (concentration 1 mg / mL), and the resulting solution was uniformly drop-coated onto a silicon wafer and allowed to dry naturally. Then, the silicon wafer was immersed in methylene blue (MB) molecular solutions of different concentrations (10... -10 M-10 -6 M) adsorption was performed for 30 minutes, followed by Raman spectroscopy. The excitation wavelength for Raman spectroscopy was 633 nm, and the laser power was 0.085 mW. The results showed that ( Figure 4 As the molecular concentration decreases, the Raman peak intensity also gradually decreases. Furthermore, the Raman peak intensity I corresponds to the logarithm of the molecular concentration (log...). 10 [C]) exhibits a good linear dependence, with a correlation coefficient greater than 0.99. These results demonstrate that the reduced graphene oxide / plasma tungsten oxide probe can be used for the quantitative analysis of low-concentration molecules.

[0041] Meanwhile, the concentration of 10 in the above experiment was adsorbed. -6 The Raman probe substrate of the MMB molecule was irradiated with a xenon lamp (the spectral wavelength of the xenon lamp was 190-1100 nm, and the irradiation power density was 200 mW·cm). -2 During this process, Raman spectra were acquired at the same location every 1 minute to monitor the degradation kinetics of MB molecules. After 5 minutes of irradiation, MB reached a concentration at 1398 cm⁻¹. -1 and 1630cm -1 The intensity of the two Raman characteristic peaks at this point drops sharply, and no obvious signal can be observed, indicating that the molecular structure of MB has been completely destroyed at this point. Figure 5The results showed a good linear relationship between ln(Raman intensity at time t / initial Raman intensity) and catalytic degradation time. The degradation rate constants of the corresponding CH and C bonds could be determined from the slope of the linear fitting curve. t [ / I0)=-kt, the slope of the fitted line is the degradation rate constant], the results show that the CH bond of MB breaks preferentially over the CC aromatic ring. Therefore, the plasma WO / rGO heterostructure can effectively photocatalyze the degradation of organic pollutants, and the order of chemical bond breaking is shown by quantitative SERS analysis, thus clearly revealing the information of the molecular catalytic mechanism.

[0042] In summary, the Raman probe based on reduced graphene oxide enhanced semiconductor plasma provided by this invention, on the one hand, can efficiently adsorb target aromatic pollutant molecules through π-π stacking interactions, thereby improving the probe's SERS activity; on the other hand, rGO can effectively stabilize semiconductor WO3. 3-x By utilizing surface oxygen vacancies, the instability of the semiconductor SPR effect is addressed, promoting the continuous generation of hot electrons and providing more reactive sites, thus improving the photocatalytic degradation performance of the probe. Simultaneously, in-situ SERS monitoring is used to obtain information on the priority of molecular chemical bond breaking, contributing to a deeper understanding of the catalytic degradation mechanism of pollutants. This probe preparation method is simple and low-cost, and it achieves efficient detection and catalytic degradation in one step, promising large-scale reusability.

[0043] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A Raman probe for reducing graphene oxide to enhance semiconductor plasma, characterized in that, The Raman probe is a composite structure of semiconductor plasma tungsten oxide nanowires loaded with reduced graphene oxide. This composite structure exhibits significant plasma resonance absorption in the 500-1400 nm wavelength region. The diameter of the plasma tungsten oxide nanowires is 5-10 nm and the length is 100-400 nm. The size of the reduced graphene oxide is 1-5 μm and the thickness is 2-6 nm. The method for preparing the Raman probe of reduced graphene oxide enhanced semiconductor plasma includes: adding graphene oxide to an ethylene glycol solution of tungsten hexachloride, stirring to form a homogeneous solution, and then carrying out a solvothermal reaction. After the reaction, the reduced graphene oxide / plasma tungsten oxide composite structure is prepared by washing and drying.

2. The Raman probe for reducing graphene oxide to enhance semiconductor plasma according to claim 1, characterized in that, The concentration of tungsten hexachloride in the ethylene glycol solution is 2-10 mg / mL, and the mass ratio of tungsten hexachloride to graphene oxide is 50-150:

1.

3. The Raman probe for reducing graphene oxide to enhance semiconductor plasma according to claim 1, characterized in that, The solvothermal reaction is carried out at a temperature of 160-200℃ for 18-30 hours.

4. The application of the Raman probe of reduced graphene oxide enhanced semiconductor plasma as described in any one of claims 1-3 in the quantitative determination of methylene blue molecule concentration.

5. The application according to claim 4, characterized in that, The method for quantifying the concentration of methylene blue molecules includes the following steps: S1. The Raman probe of reduced graphene oxide enhanced semiconductor plasma as described in claim 1 is dispersed in an ethanol solution and then drop-coated onto a substrate and allowed to dry naturally. S2. Immerse the substrate in methylene blue molecular solutions of different concentrations, and collect Raman spectra after adsorption for more than 30 minutes. S3. Plot the characteristic Raman peak intensity of methylene blue as a function of concentration, complete the standard curve fitting, and then determine the concentration of the methylene blue molecule to be tested based on the standard curve.

6. The application according to claim 5, characterized in that, The Raman probe for reduced graphene oxide-enhanced semiconductor plasma has a concentration of 0.5-3 mg / mL in ethanol solution, and the different concentrations of methylene blue molecular solutions refer to 10... -10 M-10 -6 The solution of M is a methylene blue molecular solution, and the excitation wavelength of the Raman spectrum is 633 nm with a power of 0.01-1 mW.

7. The application of the Raman probe for reduced graphene oxide enhanced semiconductor plasma as described in any one of claims 1-3 in in-situ Raman monitoring of photocatalytic degradation of methylene blue molecules.

8. The application according to claim 7, characterized in that, The method for in-situ Raman monitoring of photocatalytic degradation of methylene blue molecules is as follows: S1. The Raman probe of reduced graphene oxide enhanced semiconductor plasma as described in claim 1 is dispersed in an ethanol solution and then drop-coated onto a substrate and allowed to dry naturally. S2. Immerse the substrate in methylene blue molecular solutions of different concentrations. After adsorption for more than 30 minutes, irradiate the substrate with adsorbed methylene blue molecules with a xenon lamp. During this process, collect Raman spectra at the same position every 1 minute until the Raman signal of methylene blue can no longer be detected. S3. Plot the natural logarithm of the ratio of the characteristic peak Raman intensity of the methylene blue molecule to the initial Raman intensity at reaction time t as a function of reaction time. Determine the degradation rate constant of the chemical bond corresponding to the characteristic peak from the slope of the curve, and analyze the priority order of molecular chemical bond breaking.

9. The application according to claim 8, characterized in that, The xenon lamp has a spectral wavelength of 190-1100 nm and an irradiation power density of 100-300 mW·cm⁻¹. -2 .

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