A multi-energy band matching metal-double-semiconductor ternary heterojunction SERS sensing material, a preparation method thereof and application thereof in rapid identification of extremely low concentration organic pollutants

Abstract

The application belongs to the field of SERS detection, and relates to a multi-energy-band matching metal-double-semiconductor ternary heterojunction SERS sensing material, a preparation method thereof and application of the material in rapid identification of extremely low concentration organic pollutants. Zinc nitrate and aluminum nitrate are dissolved in deionized water and stirred, urea is added for hydrothermal reaction, and after drying, calcination is carried out to obtain [Zn 0.964 Al 0.036 ][Al 1.964 Zn 0.036 ]O4. Bismuth nitrate and potassium iodide are respectively dissolved in ethylene glycol, the potassium iodide solution is added to the bismuth nitrate pentahydrate solution and stirred, the ph is adjusted to alkaline, [Zn 0.964 Al 0.036 ][Al 1.964 Zn 0.036 ]O 4、 silver nitrate is added, hydrothermal reaction is carried out, and the target product is obtained after drying. The application constructs a "metal-semiconductor" multi-element heterojunction, the interface defects are rich, which is beneficial to local electromagnetic field coupling and charge transmission, and electromagnetic+chemical+energy band triple synergistic enhancement is realized.

Description

Technical Field

[0001] This invention belongs to the field of SERS detection, specifically relating to a multi-band matched metal-double semiconductor ternary heterojunction SERS sensing material, its preparation method, and its application in the rapid identification of extremely low concentration organic pollutants. Background Technology

[0002] Surface-enhanced Raman scattering (SERS) technology has been widely used in trace analysis of organic pollutants, environmental monitoring, and food safety due to its advantages such as ultra-high detection sensitivity, rapid response, and ease of operation. High-performance SERS substrates are the core key to achieving highly sensitive detection.

[0003] Traditional SERS substrates are mostly based on single noble metals, relying on electromagnetic enhancement effects to amplify signals. However, they suffer from drawbacks such as easy material aggregation, poor chemical stability, high cost, and reliance on a single enhancement mechanism, making it difficult to further improve detection sensitivity and anti-interference capabilities. While pure semiconductor substrates offer excellent chemical stability, they generally suffer from weak Raman enhancement and low charge separation efficiency.

[0004] Bismuth-based oxyiodide Bi4O5I2, as a novel visible light responsive semiconductor material, has become a preferred semiconductor component for SERS substrates due to its suitable band structure, abundant surface active sites, excellent charge migration ability and chemical stability. Its unique layered crystal structure can construct a large number of heterojunctions, which can effectively promote charge separation and transport. At the same time, it can form strong interfacial coupling with noble metals to help amplify Raman signals, showing significant application potential in composite SERS materials.

[0005] To address the limitations of single-material substrates, the academic community has gradually developed metal-semiconductor composite substrates, utilizing a combination of electromagnetic and chemical enhancements to improve SERS performance. However, existing binary composite heterojunctions still suffer from problems such as simple interface structures, insufficient defect numbers, high charge transport resistance, and limited local electromagnetic field coupling effects. The synergistic effect of multiple enhancements is difficult to fully realize, and the detection limit and signal reproducibility still fail to meet the actual trace detection requirements when dealing with low concentrations of organic pollutants. Summary of the Invention

[0006] To address the shortcomings of existing SERS (Self-Enhancing Reactor) technologies, such as limited substrate enhancement mechanisms, poor interfacial performance, insufficient sensitivity, and poor stability, which hinder the detection of trace organic pollutants, this invention provides a multi-band-matched metal-dual-semiconductor ternary heterojunction SERS sensing material, its preparation method, and its application in the rapid identification of extremely low concentration organic pollutants. This multi-band-matched metal-dual-semiconductor ternary heterojunction SERS sensing material combines the structural and performance advantages of Bi4O5I2 semiconductor materials to construct a multi-element composite heterostructure, achieving synergistic enhancement of electromagnetic, chemical, and band structures. It exhibits high SERS activity, good chemical stability, and signal reproducibility, enabling efficient trace detection of organic pollutants such as those found in CV (Continuous Vibration) sensors.

[0007] The technical solution adopted in this invention is as follows: a method for preparing a multi-band matched metal-double semiconductor ternary heterojunction SERS sensing material, comprising the following steps.

[0008] 1) Using zinc nitrate hexahydrate, aluminum nitrate nonahydrate, and urea as raw materials, [Zn] is obtained through hydrothermal processing and calcination. 0.964 Al 0.036 ][Al 1.964 Zn 0.036 O4 nanoparticles.

[0009] 2) Using bismuth nitrate pentahydrate, potassium iodide, and silver nitrate as raw materials, a one-step hydrothermal method is employed to process [Zn] 0.964 Al 0.036 ][Al 1.964 Zn 0.036 Bi4O5I2 and Ag were grown in situ on the surface of ZnO4 nanoparticles to prepare the target product Ag / Bi4O5I2 / [ZnO4]O4 nanoparticles. 0.964 Al 0.036 ][Al 1.964 Zn 0.036 O4 composite SERS substrate.

[0010] The above describes a method for preparing a multi-band matched metal-double semiconductor ternary heterojunction SERS sensing material.

[0011] In step 1), specifically, zinc nitrate hexahydrate and aluminum nitrate nonahydrate are dissolved in water and mixed, then urea is added, and a hydrothermal reaction is carried out at a temperature of 120-180℃ for 6-8 hours. After cooling, the mixture is centrifuged, washed, dried, and calcined to obtain [Zn]. 0.964 Al 0.036 ][Al 1.964 Zn 0.036 O4 nanoparticles; the calcination temperature is 550-600℃, and the time is 3-4h.

[0012] In the above-mentioned method for preparing a multi-band matched metal-dual semiconductor ternary heterojunction SERS sensing material, the molar ratio of zinc nitrate hexahydrate: aluminum nitrate nonahydrate: urea is 1:2:6.

[0013] In the above-mentioned method for preparing a multi-band matched metal-double semiconductor ternary heterojunction SERS sensing material, step 2) specifically involves dissolving bismuth nitrate pentahydrate and potassium iodide separately in ethylene glycol, slowly adding the potassium iodide solution dropwise to the bismuth nitrate solution, adjusting the pH to alkaline, and then adding the prepared [Zn] to the solution. 0.964 Al 0.036 ][Al 1.964 Zn 0.036 [O4 nanoparticles and silver nitrate undergo a hydrothermal reaction to yield Ag / Bi4O5I2 / [Zn] 0.964 Al 0.036 ][Al 1.964 Zn 0.036 O4 composite material.

[0014] The preparation method of the above-mentioned multi-band matched metal-double semiconductor ternary heterojunction SERS sensing material, wherein adjusting the pH to alkaline involves adding sodium hydroxide solution to adjust the pH value to 10-11, and the hydrothermal reaction is carried out at 160-170℃ for 12-18 hours.

[0015] The above-mentioned method for preparing a multi-band matched metal-double semiconductor ternary heterojunction SERS sensing material comprises: bismuth nitrate pentahydrate: potassium iodide: silver nitrate: [Zn 0.964 Al 0.036 ][Al 1.964 Zn 0.036 ]O4=4-5mol: 3-4mol: 600-650g: 9900-10000g.

[0016] The above-mentioned method for preparing a multi-band matched metal-double semiconductor ternary heterojunction SERS sensing material comprises: bismuth nitrate pentahydrate: potassium iodide: silver nitrate: [Zn 0.964 Al 0.036 ][Al 1.964 Zn 0.036 O4 = 2 × 10 -5 mol, 1.5 × 10 - 5 mol, 3.15 × 10 -3 g, 0.1g.

[0017] A multi-band matched metal-double semiconductor ternary heterojunction SERS sensing material prepared by the above-described preparation method.

[0018] An application of a multi-band matched metal-dual semiconductor ternary heterojunction SERS sensing material as described above in the rapid identification of extremely low concentration organic pollutants.

[0019] In the above application, the organic pollutant is crystal violet.

[0020] The above application involves adding a multi-band matched metal-double semiconductor ternary heterojunction SERS sensing material to a crystal violet solution, and performing surface-enhanced Raman scattering detection using a 532nm wavelength laser as the excitation source. The concentration of the crystal violet solution is 10. -3 -10 -7 mol / L.

[0021] The present invention has the following beneficial effects.

[0022] (1) The present invention constructs a ternary heterostructure, relying on the electromagnetic enhancement effect of noble metal Ag, the chemical enhancement effect brought about by the rich active sites of Bi4O5I2, and the band enhancement effect formed by band matching, the three mechanisms synergistically amplify the Raman signal and greatly improve the detection sensitivity.

[0023] (2) By taking advantage of the layered structure of Bi4O5I2 and combining it with the ternary heterojunction to form a large number of closely contacted interfaces and defect sites, photogenerated carrier recombination can be effectively suppressed, the interface charge transfer rate can be accelerated, and the SERS enhancement effect and signal stability can be further improved.

[0024] (3) The composite substrate combines the chemical stability of Bi4O5I2 and zinc-aluminum oxides, while retaining the high SERS activity of precious metal silver. The material is not easy to agglomerate, is resistant to environmental interference, and has good Raman signal reproducibility. It can be applied to the rapid on-site detection of CV organic pollutants in water and has a wide range of applicable scenarios. Attached Figure Description

[0025] Figure 1 This is the Raman spectrum of CV solid molecules under a 532nm laser in Example 2, and the CV adsorption on Ag / Bi4O5I2 / [Zn 0.964 Al 0.036 ][Al 1.964 Zn 0.036 SERS spectrum on O4 composite SERS substrate.

[0026] Figure 2 It is Ag / Bi4O5I2 / [Zn] in Example 1 0.964 Al 0.036 ][Al 1.964 Zn 0.036 XRD pattern of O4 composite material.

[0027] Figure 3In Example 3, a 532nm laser was used to irradiate Ag / Bi4O5I2 / [Zn] 0.964 Al 0.036 ][Al 1.964 Zn 0.036 SERS spectra of CV molecules collected after six random Raman detections on an O4 composite substrate.

[0028] Figure 4 In Example 3, Ag / Bi4O5I2 / [Zn] was irradiated with different laser intensities. 0.964 Al 0.036 ][Al 1.964 Zn 0.036 SERS spectra of CV molecules collected by Raman detection on an O4 composite substrate.

[0029] Figure 5 Example 3 shows the adsorption of different concentrations of CV molecules onto Ag / Bi4O5I2 / [Zn] under a 532nm laser. 0.964 Al 0.036 ][Al 1.964 Zn 0.036 SERS spectrum on O4 composite substrate.

[0030] Figure 6 The CV concentration in Example 3 is related to 1618 cm⁻¹. -1 Logarithmic relationship between characteristic peak SERS intensities. Detailed Implementation

[0031] To better understand the technical solution of the present invention, specific embodiments are provided for further detailed description, but the solution is not limited thereto.

[0032] Example 1.

[0033] Ag / Bi4O5I2 / [Zn 0.964 Al 0.036 ][Al 1.964 Zn 0.036 The preparation scheme for O4 is as follows.

[0034] 1) Dissolve 2.23 g of zinc nitrate hexahydrate and 5.63 g of aluminum nitrate nonahydrate in 60 ml of deionized water and stir until the solution is clear. Add 1.8 g of urea to the above solution and stir until completely dissolved. Perform a hydrothermal reaction at 180 °C for 6 h. After cooling to room temperature, centrifuge, wash, and dry the product. Calcine at 550 °C for 4 h to obtain [Zn]. 0.964 Al 0.036 ][Al 1.964 Zn 0.036 O4 nanoparticles.

[0035] 2) Dissolve 10 mg of bismuth nitrate pentahydrate and 2.5 mg of KI in 30 ml and 10 ml of ethylene glycol, respectively. Add the KI solution dropwise to the bismuth nitrate pentahydrate solution and stir for 30 min to obtain a mixed solution. Slowly add a 0.5 mol / L NaOH solution to the mixed solution, adjust the pH to 10-11, stir for 30 min, and take 100 mg of [Zn] 0.964 Al 0.036 ][Al 1.964 Zn 0.036 [O4 and 3.15 mg AgNO3 were added to the mixed solution, and the mixture was hydrothermally heated at 160 °C for 18 h. After cooling to room temperature, the product was centrifuged, cooled, washed, and dried to obtain Ag / Bi4O5I2 / [Zn] 0.964 Al 0.036 ][Al 1.964 Zn 0.036 O4 composite SERS substrate.

[0036] Take the prepared Ag / Bi4O5I2 / [Zn 0.964 Al 0.036 ][Al 1.964 Zn 0.036 XRD tests were performed on the O4 composite SERS substrate, and the test results are as follows: Figure 2 As shown, the characteristic diffraction peaks appearing at 2θ = 38.2°, 44.4°, 64.6°, and 77.5° correspond to the characteristic peaks of Ag. The XRD diffraction peaks at 2θ = 28.7° and 31.3° correspond to the characteristic peaks of Bi4O5I2; the XRD diffraction peaks at 2θ = 31.3° and 36.9° correspond to the characteristic peaks of [Zn]. 0.964 Al 0.036 ][Al 1.964 Zn 0.036 The XRD pattern obtained from the test is sufficient to illustrate Ag / Bi4O5I2 / [Zn] 0.964 Al 0.036 ][Al 1.964 Zn 0.036 The O4 composite substrate was successfully synthesized.

[0037] Example 2.

[0038] Ag / Bi4O5I2 / [Zn 0.964 Al 0.036 ][Al 1.964 Zn 0.036 SERS enhancement effect of O4 composite SERS substrate.

[0039] The Ag / Bi4O5I2 / [Zn] prepared in Example 1 was used. 0.964 Al 0.036 ][Al 1.964 Zn0.036 An O4 composite SERS substrate was used, and experiments were conducted using CV as the probe molecule based on SERS technology. The testing procedure was as follows: a 532nm wavelength laser was used as the excitation source, and 2 ml of a 10% concentration was used based on SERS technology. -3 Using 10 mg Ag / Bi4O5I2 / [Zn] mol / L as a probe molecule, the probe molecule was prepared in Example 1. 0.964 Al 0.036 ][Al 1.964 Zn 0.036 The O4 composite SERS substrate was mixed with the above-mentioned crystal violet solution, ultrasonicated, and then loaded onto a glass slide to form a composite SERS substrate for testing. Individual CV and Ag / Bi4O5I2 / [Zn] were tested separately. 0.964 Al 0.036 ][Al 1.964 Zn 0.036 SERS detection was performed on both cases involving O4 composite SERS substrate mixing, and the results are as follows: Figure 1 Ag / Bi4O5I2 / [Zn] using CV molecules as probes 0.964 Al 0.036 ][Al 1.964 Zn 0.036 The Raman signal intensity of the Ag / Bi4O5I2 / [Zn] composite SERS substrate is much higher than that of the single CV molecule, which indicates that the Ag / Bi4O5I2 / [Zn] prepared in this invention... 0.964 Al 0.036 ][Al 1.964 Zn 0.036 The O4 composite SERS substrate exhibits excellent SERS signal enhancement performance.

[0040] Example 3.

[0041] Ag / Bi4O5I2 / [Zn 0.964 Al 0.036 ][Al 1.964 Zn 0.036 Other excellent properties of O4 composite SERS substrate.

[0042] Take 10 mg of Ag / Bi4O5I2 / [Zn] prepared in Example 1 0.964 Al 0.036 ][Al 1.964 Zn 0.036 An O4 composite SERS substrate was used, and a 532nm wavelength laser was used as the excitation source on this composite SERS substrate. Based on SERS technology, 2 ml of a 10% concentration was used. -3 mol / L CV was used as a probe molecule with 10 mg of Ag / Bi4O5I2 / [Zn] prepared in Example 1. 0.964 Al 0.036][Al 1.964 Zn 0.036 O4 composite SERS substrates were mixed and loaded onto a glass slide, dispersed, and then six points were randomly selected for testing. The results are as follows: Figure 3 As shown, the Raman signal peaks were uniform and showed no significant changes in the six tests, indicating that the substrate has good stability and uniformity.

[0043] The Ag / Bi4O5I2 / [Zn] element was irradiated with lasers of different intensities of 0.25mW, 0.5mW, and 0.025mW respectively. 0.964 Al 0.036 ][Al 1.964 Zn 0.036 The SERS spectrum obtained by Raman spectroscopy on the O4 composite SERS substrate is shown below. Figure 4 As shown, the results indicate that the composite SERS substrate exhibits good detection sensitivity and excellent enhancement effect at laser intensities of 0.25mW and 0.5mW.

[0044] Using CV molecules of different concentrations as probe molecules in Ag / Bi4O5I2 / [Zn 0.964 Al 0.036 ][Al 1.964 Zn 0.036 The results were obtained by detection on an O4 composite SERS substrate. Figure 5 As shown, although the signal peak intensity decreases with decreasing CV probe molecule concentration, Raman signals can still be detected at extremely low concentrations, indicating that this substrate can detect different concentrations of CV molecules (10). -3 -10 - 7 (mol / L), and it still exhibits good performance at extremely low concentrations. The relationship between the SERS signal peak intensities under different concentrations of the CV probe was analyzed, and the results are as follows: Figure 6 As shown, the equation obtained after fitting is y=(59633.5)+(7381.7)X, R 2 =0.98547, this result further illustrates the relationship between CV concentration and 1618 cm⁻¹. -1 The logarithmic relationship between the characteristic peak SERS intensities confirms that this composite material can quantitatively detect the concentration of crystal violet, demonstrating excellent performance in SERS-based analytical applications.

Claims

1. A method for preparing a multi-bandgap matched metal-double semiconductor ternary heterojunction SERS sensing material, characterized in that: Includes the following steps: 1) Using zinc nitrate hexahydrate, aluminum nitrate nonahydrate, and urea as raw materials, [Zn] is obtained through hydrothermal processing and calcination. 0.964 Al 0.036 ][Al 1.964 Zn 0.036 O4 nanoparticles; 2) Using bismuth nitrate pentahydrate, potassium iodide, and silver nitrate as raw materials, a one-step hydrothermal method is employed to process [Zn] 0.964 Al 0.036 ][Al 1.964 Zn 0.036 Bi4O5I2 and Ag were grown in situ on the surface of ZnO4 nanoparticles to prepare the target product Ag / Bi4O5I2 / [ZnO4]O4 nanoparticles. 0.964 Al 0.036 ][Al 1.964 Zn 0.036 O4 composite SERS substrate.

2. The method for preparing a multi-band matched metal-double semiconductor ternary heterojunction SERS sensing material as described in claim 1, characterized in that: In step 1), specifically, zinc nitrate hexahydrate and aluminum nitrate nonahydrate are dissolved in water and mixed, then urea is added, and a hydrothermal reaction is carried out at a temperature of 120-180℃ for 6-8 hours. After cooling, the mixture is centrifuged, washed, dried, and calcined to obtain [Zn]. 0.964 Al 0.036 ][Al 1.964 Zn 0.036 O4 nanoparticles; the calcination temperature is 550-600℃, and the time is 3-4h.

3. The method for preparing a multi-band matched metal-double semiconductor ternary heterojunction SERS sensing material as described in claim 1, characterized in that: The molar ratio of zinc nitrate hexahydrate: aluminum nitrate nonahydrate: urea is 1:2:

6.

4. The method for preparing a multi-band matched metal-double semiconductor ternary heterojunction SERS sensing material as described in claim 1, characterized in that: Step 2) specifically involves dissolving bismuth nitrate pentahydrate and potassium iodide separately in ethylene glycol, slowly adding the potassium iodide solution dropwise to the bismuth nitrate solution, adjusting the pH to alkaline, and then adding the prepared [Zn] solution. 0.964 Al 0.036 ][Al 1.964 Zn 0.036 [O4 nanoparticles and silver nitrate undergo a hydrothermal reaction to yield Ag / Bi4O5I2 / [Zn] 0.964 Al 0.036 ][Al 1.964 Zn 0.036 O4 composite SERS substrate.

5. The method for preparing a multi-band matched metal-double semiconductor ternary heterojunction SERS sensing material as described in claim 4, characterized in that: The pH adjustment to alkalinity is achieved by adding sodium hydroxide solution to adjust the pH value to 10-11, and the hydrothermal reaction is carried out at 160-170℃ for 12-18 hours.

6. The method for preparing a multi-band matched metal-double semiconductor ternary heterojunction SERS sensing material as described in claim 4, characterized in that: Bismuth nitrate pentahydrate: Potassium iodide: Silver nitrate: [Zn 0.964 Al 0.036 ][Al 1.964 Zn 0.036 ]O4=4-5mol: 3-4mol: 600-650g: 9900-10000g.

7. A multi-band matched metal-double semiconductor ternary heterojunction SERS sensing material prepared by the preparation method according to any one of claims 1-6.

8. The application of a multi-band matched metal-dual semiconductor ternary heterojunction SERS sensing material as described in claim 7 in the rapid identification of extremely low concentration organic pollutants.

9. The application as described in claim 8, characterized in that: The organic pollutant mentioned is crystal violet.

10. The application as described in claim 9, characterized in that: A multi-band matched metal-double semiconductor ternary heterojunction SERS sensing material was added to a crystal violet solution, and surface-enhanced Raman scattering detection was performed using a 532 nm wavelength laser as the excitation source. The concentration of the crystal violet solution was 10. -3 -10 -7 mol / L.

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