阅读说明：本技术 一种黑色多孔ZnO材料在SERS检测中的应用 (Application of black porous ZnO material in SERS detection ) 是由 朱青 罗蔓 陈晓露 于 2021-07-05 设计创作，主要内容包括：本发明公开了一种黑色多孔ZnO材料在SERS检测中的应用,以黑色多孔ZnO材料作为基底,对待测物进行吸附后进行SERS检测,其中黑色多孔ZnO材料的表面富含无序晶格缺陷结构,是以锌基金属有机框架化合物为原料,先经过高温煅烧,再在保护气氛下,采用还原剂进行高温还原制得。本发明采用黑色多孔ZnO材料作为基底进行SERS检测,其SERS检测性能可以接近传统的贵金属纳米晶SERS基底,并且具有较高的化学稳定性、规整的结构和低廉的价格,有利于SERS活性基底的便捷、迅速、大批量生产。(The invention discloses an application of a black porous ZnO material in SERS detection, which is characterized in that the black porous ZnO material is used as a substrate, an object to be detected is adsorbed and then SERS detection is carried out, wherein the surface of the black porous ZnO material is rich in an unordered lattice defect structure, a zinc-based metal organic framework compound is used as a raw material, and the black porous ZnO material is prepared by firstly carrying out high-temperature calcination and then carrying out high-temperature reduction by adopting a reducing agent under a protective atmosphere. The invention adopts black porous ZnO material as the substrate to carry out SERS detection, the SERS detection performance of the invention can be close to that of the traditional precious metal nanocrystalline SERS substrate, and the invention has higher chemical stability, regular structure and low price, and is beneficial to the convenient, rapid and mass production of the SERS active substrate.)

1. The application of the black porous ZnO material in SERS detection is characterized in that the surface of the black porous ZnO material is rich in disordered lattice defect structures.

2. The application of claim 1, wherein the black porous ZnO material is prepared by using a zinc-based metal organic framework compound as a raw material, calcining at high temperature, and reducing at high temperature by using a reducing agent in a protective atmosphere.

3. Use according to claim 2, characterized in that the zinc-based metal organic framework compound is ZIF-8.

4. The use according to any one of claims 1 to 3, wherein the black porous ZnO material is prepared by a method comprising the following steps:

s1, heating the ZIF-8 material to 500-650 ℃ at a certain heating rate, and then preserving heat for 3-5h to obtain a white porous ZnO material;

s2, uniformly mixing the white porous ZnO material obtained in the step S1 with a reducing agent, annealing for 1-2h at the temperature of 300-350 ℃ in an inert atmosphere, cooling, washing and drying to obtain the black porous ZnO material.

5. The application of the ZnO-based composite material as claimed in claim 4, wherein the mass ratio of the white porous ZnO material to the reducing agent is 1 (1-2); the reducing agent is NaBH₄。

6. The use according to claim 4 or 5, wherein in step S1, the temperature rise rate is 5-10 ℃/min.

7. The application of any one of claims 1 to 6, wherein the black porous ZnO material is used as a substrate, and SERS detection is performed after an object to be detected is adsorbed.

8. The use of claim 7, wherein the analyte is methylene blue.

Technical Field

The invention relates to the technical field of molecular recognition, in particular to application of a black porous ZnO material in SERS detection.

Background

In the last 70 th century, Fleischmann and Van Duyne et al performed Raman (Raman) spectroscopy on roughened silver electrode surfaces, and they discovered that roughened silver surfaces could amplify the Raman signal of molecules, which they named the surface enhanced Raman Scattering Effect (SERS). Through the scientific development of recent decades, the Surface Enhanced Raman Scattering (SERS) technology has become a very important trace-level even single-molecule-level label-free detection method. As a highly sensitive, non-contact, non-destructive detection technique, SERS has been widely used in the fields of environmental detection, bio-imaging, medical diagnosis, fingerprint molecule differentiation, catalytic reaction monitoring, and the like.

Conventional SERS substrate materials are based on noble metal nanostructures with rough surfaces, including gold (Au), silver (Ag), platinum (Pt), etc. The Surface Plasmon Resonance (SPR) effect caused by the enhancement of the local electric field on the surface of noble metals, particularly the occurrence of a large number of "hot spots" (regions of high intensity electromagnetic field formed at the nano-scale noble metal gap) is considered as a well-known enhancement mechanism for enhancing raman scattering, i.e., an Electromagnetic Mechanism (EM). The Raman signal Enhancement Factor (EFs) of the analyte on the surface of these noble metal substrates was 10⁶Or higher, the lowest detectable Limit (LOD) of the analyte may be less than 10^-7The concentration of M. However, the EM-based noble metal SERS substrate generally requires a complicated and precise preparation process, which makes it lack of structural controllability and reproducibility of a signal substrate, and most importantly, the noble metal itself is expensive, which limits the use cost thereof and also limits practical applications. In addition, noble metals also have the disadvantages of high cost, poor biocompatibility, easy occurrence of photo-corrosion and the like. Yet another commonly accepted mode of Raman enhancement, the chemical enhancement mechanism (CM), is primarily referred to as the charge transfer process between SERS substrates and molecules adsorbed on their surfaces. The charge transfer will cause molecular resonance, which will greatly increase the polarizability of the adsorbed molecules, and the corresponding raman scattering cross-section will increase, resulting in an enhancement of the SERS signal. Although researchers generally accept that the SERS phenomenon is a result of the combination of EM and CM, CM is generally considered to play only a minor role because charge transfer is a short-range effect, existing only at the interface between the SERS substrate and the molecule to be measured.

Following the first generation of SERS technologies based on EM dominated noble metal materials, CM based non-noble metal substrates have gained a great deal of force in recent yearsDevelopment, many semiconductor nanostructures, including Cu₂O, polycrystalline Si, W₁₈O₄₉，TiO₂，MoO₂The conducting polymer and the metal organic framework compound form a second generation SERS substrate. Compared with the noble metal SERS substrate, the nano-structure semiconductor has a tunable energy band structure and richer resonance modes, so that the corresponding working excitation wavelength (such as 532nm, 647nm, 785nm and the like) for detecting the target analyte can be effectively controlled. In addition to these features, semiconductor SERS substrates have excellent biocompatibility, easily controllable micro-topography, and richer surface active sites. However, for the two most important parameters of SERS, raman Enhancement Factor (EFs) and lowest detectable Limit (LOD) of the analyte, CM-based semiconductor materials are typically much lower than EM-driven noble metals. Therefore, a non-noble metal SERS substrate material with low cost, high sensitivity, high stability and large-area signal uniformity needs to be found urgently to replace the traditional noble metal material so as to realize the practical application of the SERS detection technology.

Disclosure of Invention

Based on the technical problems in the background art, the invention provides an application of a black porous ZnO material in SERS detection.

The invention provides application of a black porous ZnO material in SERS detection.

Preferably, the black porous ZnO material is prepared by using a zinc-based metal organic framework compound as a raw material, calcining at high temperature, and reducing at high temperature by using a reducing agent in a protective atmosphere.

Preferably, the zinc-based metal organic framework compound is ZIF-8.

Preferably, the preparation method of the black porous ZnO material comprises the following steps:

s1, heating the ZIF-8 material to 500-650 ℃ at a certain heating rate, and then preserving heat for 3-5h to obtain a white porous ZnO material;

s2, uniformly mixing the white porous ZnO material obtained in the step S1 with a reducing agent, annealing for 1-2h at the temperature of 300-350 ℃ in an inert atmosphere, cooling, washing and drying to obtain the black porous ZnO material.

Preferably, the mass ratio of the white porous ZnO material to the reducing agent is 1 (1-2); the reducing agent is NaBH₄。

Preferably, in the step S1, the temperature rise rate is 5-10 ℃/min.

Preferably, the inert atmosphere is at least one of an argon atmosphere and a nitrogen atmosphere.

The ZIF-8 material can be prepared by a conventional method, for example, the preparation method comprises the following steps:

adding Zn (CH)₃COO)₂Dissolving polyvinylpyrrolidone in methanol to obtain a solution A, dissolving 2-methylimidazole in methanol to obtain a solution B, mixing the solution A and the solution B at 0-5 ℃, uniformly stirring, standing at room temperature for 20-30h, collecting precipitate, washing and drying to obtain the compound preparation; wherein, Zn (CH)₃COO)₂The molar ratio to 2-methylimidazole is preferably 1: (3-4), Zn (CH)₃COO)₂The mass ratio of polyvinylpyrrolidone is preferably 1: (1.5-2), the stirring time after the solution A and the solution B are mixed is preferably 1-2 h.

Preferably, the application method of the black porous ZnO material in SERS detection comprises the following steps: and absorbing the object to be detected by using the black porous ZnO material as a substrate, and then carrying out SERS detection.

Preferably, the analyte is methylene blue.

The invention has the following beneficial effects:

the invention provides application of a black porous ZnO material in SERS detection, and the black porous ZnO material adopted by the invention is prepared by taking a zinc-based metal organic framework compound, particularly a ZIF-8 material as a raw material and adopting a simple calcination reaction, and the surface of the black porous ZnO material is rich in a disordered lattice defect structure. The SERS substrate is prepared by taking a metal organic framework compound as a precursor, so that the porosity is reserved, the scattering probability of light waves among pores in the material is promoted, and the combined action of the disordered lattice defect structure rich in the surface of the material accelerates the speed of the SERS substrate and the dye molecules to be detectedAnd the intensity of a Raman spectrum signal of the dye molecule adsorbed on the surface of the material is greatly amplified by charge exchange. The SERS substrate can realize high-sensitivity Raman spectrum detection of methylene blue molecules at room temperature, and the lower limit of detection can be as low as 1 x 10^-7mol/L, corresponding Raman enhancement factor up to 2.5 × 10⁶The SERS detection performance of the nano-crystalline noble metal nano-crystalline SERS substrate can be close to that of the traditional nano-crystalline noble metal SERS substrate, and the nano-crystalline noble metal nano-crystalline SERS substrate is simple to prepare, low in operating condition requirement, high in yield, high in chemical stability, regular in structure and low in price, and is beneficial to convenient, rapid and mass production of the SERS active substrate.

Drawings

Fig. 1 is a photograph of a white ZnO sample and a black ZnO sample prepared in example 1, wherein fig. 1(a) is the white ZnO sample and fig. 1(B) is the black ZnO sample.

FIG. 2 is SEM photographs of the ZIF-8 material prepared in example 1 and a black ZnO sample, wherein FIG. 2(A) is the ZIF-8 material and FIG. 2(B) is the black ZnO sample.

Fig. 3 is an XRD pattern of the black ZnO sample prepared in example 1.

FIG. 4 is a paramagnetic spectrum of a white ZnO sample and a black ZnO sample prepared in example 1.

Fig. 5 is a TEM image of a black ZnO sample in example 1.

Fig. 6 shows SERS performance test results of the white ZnO sample and the black ZnO sample prepared in example 1, where fig. 6(a) shows the SERS performance test results of the black ZnO sample, and fig. 6(B) shows the SERS performance test results of the white ZnO sample.

FIG. 7 shows the concentration of 1X 10^-1And (3) Raman test results of the methylene blue solution of mol/L.

Detailed Description

The technical solution of the present invention will be described in detail below with reference to specific examples.

Example 1

Preparing a ZIF-8 material:

0.176g of Zn (CH) is weighed₃COO)₂And 0.300g of polyvinylpyrrolidone (PVP) dissolved in 20mL of methanol to give solution A; will be provided withDissolving 0.263g of 2-methylimidazole in 20mL of methanol to obtain a solution B; mixing the solution A and the solution B at 5 ℃, stirring for 1h, standing at 25 ℃ for 24h, collecting the precipitate, washing with methanol for 3 times, and vacuum drying for 12h to obtain the final product.

Preparing a black porous ZnO material:

s1, weighing a proper amount of the prepared ZIF-8 material, placing the material in a high-temperature muffle furnace, heating to 500 ℃ at a heating rate of 5 ℃/min, and then preserving heat for 3h to obtain white porous ZnO powder;

s2, weighing a proper amount of the white porous ZnO material prepared in the step S1 and NaBH₄Uniformly mixing, wherein the white porous ZnO material and NaBH₄The mass ratio of the ZnO powder to the black powder is 1:2, annealing treatment is carried out for 1h at 300 ℃ in a nitrogen atmosphere, cooling is carried out to room temperature, then washing is carried out for 3 times by respectively using water and ethanol, and vacuum drying is carried out for 12h at 60 ℃ to obtain black porous ZnO powder.

And respectively taking proper amounts of the prepared ZIF-8 material, white porous ZnO powder and black porous ZnO powder for characterization, wherein the results are shown in figures 1-5.

Fig. 1 is a photograph of a white ZnO sample and a black ZnO sample prepared in example 1, wherein fig. 1(a) is the white ZnO sample and fig. 1(B) is the black ZnO sample.

FIG. 2 is SEM photographs of the ZIF-8 material prepared in example 1 and a black ZnO sample, wherein FIG. 2(A) is the ZIF-8 material and FIG. 2(B) is the black ZnO sample. As can be seen from fig. 2, the black porous ZnO powder prepared above is a polyhedral structure, and is assembled from a plurality of nanoparticles.

Fig. 3 is an XRD pattern of the black ZnO sample prepared in example 1. As can be seen from fig. 3, the crystal structure of the black porous ZnO powder prepared above is a pure wurtzite phase, consistent with the standard cards in the database.

FIG. 4 is a paramagnetic spectrum of a white ZnO sample and a black ZnO sample prepared in example 1. As can be seen from fig. 4, the black porous ZnO powder prepared as described above had a large number of oxygen vacancy structures in the lattice structure, while the white porous ZnO powder had no oxygen vacancy structure in the lattice structure.

Fig. 5 is a TEM image of a black ZnO sample in example 1. As can be seen from fig. 5, the black porous ZnO powder prepared as described above has many disordered lattice components on the surface.

Respectively taking appropriate amount of the prepared white porous ZnO powder and black porous ZnO powder as SERS substrates, and taking the concentration of the white porous ZnO powder and the black porous ZnO powder as 10^-5mol/L,10^-6mol/L,10^-7And taking the methylene blue aqueous solution of mol/L as a sample to be detected to carry out SERS detection. The experimental procedure was as follows: weighing 5mg of SERS substrate, adding the SERS substrate into 50mL of sample to be tested, adsorbing for 12h, centrifuging, taking out solid, dropping on a silicon wafer, drying, and performing Raman test under the following test conditions: excitation wavelength 532nm, laser power 1mW and integration time 10 s. The results are shown in FIG. 6.

At a concentration of 1X 10^-1A Raman test was carried out using a methylene blue solution in mol/L as a control sample. The experimental procedure was as follows: and (3) dropping 50mL of a control sample on a silicon wafer, drying and then carrying out Raman test under the following test conditions: excitation wavelength 532nm, laser power 1mW and integration time 10 s. The results are shown in FIG. 7.

As can be seen from FIG. 6, the black porous ZnO powder is used as the SERS substrate, and the detection limit of methylene blue can reach 10^-7mol/L, while the white porous ZnO powder can only reach 10^-5mol/L. Combining the experimental results of fig. 6 and 7, according to the formula: EF ═ I (I)_SERS/C_SERS)/(I_bulk/C_bulk) And the calculated SERS enhancement factor of black ZnO can reach 2.5 multiplied by 10⁶. In the formula I_SERSThe peak height of a methylene blue molecular characteristic peak of a sample to be detected is obtained through SERS detection; c_SERSThe concentration of methylene blue in a sample to be detected; i is_bulkThe peak height of the characteristic peak of the methylene blue molecule obtained by Raman testing of a control sample; c_bulkConcentration of methylene blue in the control sample.

Therefore, compared with a white defect-free porous ZnO material, the SERS detection limit and the Raman enhancement factor of the prepared black porous ZnO powder are greatly improved.

Example 2

Preparing a ZIF-8 material:

0.088g Zn (CH) was weighed out₃COO)₂And 0.150g of polyvinylpyrrolidone (PVP) dissolved in 10mL of methanol to give solution A; dissolving 0.140g of 2-methylimidazole in 10mL of methanol to obtain a solution B; mixing the solution A and the solution B at the temperature, stirring for 1h, standing at the room temperature of 25 ℃ for 28h, collecting the precipitate, washing with methanol for 3 times, and vacuum drying for 12h to obtain the final product.

Preparing a black porous ZnO material:

s1, placing the prepared ZIF-8 material in a high-temperature muffle furnace, heating to 550 ℃ at a heating rate of 8 ℃/min, and then preserving heat for 3.5 hours to obtain white porous ZnO powder;

s2, mixing the white porous ZnO material prepared in the step S1 and NaBH₄Uniformly mixing, wherein the white porous ZnO material and NaBH₄The mass ratio of the ZnO powder to the black powder is 1:1.5, annealing treatment is carried out for 1.5h at 320 ℃ in the nitrogen atmosphere, cooling is carried out to room temperature, then water and ethanol are respectively used for washing for 3 times, and vacuum drying is carried out for 12h at 60 ℃ to obtain the black porous ZnO powder.

Example 3

Preparing a ZIF-8 material:

0.352g of Zn (CH) is weighed₃COO)₂And 0.650g of polyvinylpyrrolidone (PVP) dissolved in 30mL of methanol to give solution A; dissolving 0.526g of 2-methylimidazole in 30mL of methanol to obtain a solution B; mixing the solution A and the solution B at 5 ℃, stirring for 1.5h, standing at room temperature of 25 ℃ for 30h, collecting precipitate, washing with methanol for 3 times, and vacuum drying for 12h to obtain the final product.

Preparing a black porous ZnO material:

s1, placing the prepared ZIF-8 material in a high-temperature muffle furnace, heating to 600 ℃ at a heating rate of 10 ℃/min, and then preserving heat for 4h to obtain white porous ZnO powder;

s2, mixing the white porous ZnO material prepared in the step S1 and NaBH₄Uniformly mixing, wherein the white porous ZnO material and NaBH₄The mass ratio of the ZnO powder to the black powder is 1:1.7, annealing treatment is carried out for 2h at 340 ℃ in nitrogen atmosphere, cooling to room temperature is carried out, then water and ethanol are respectively used for washing for 3 times, and vacuum drying is carried out for 12h at 60 ℃ to obtain the black porous ZnO powder.

Example 4

Preparing a ZIF-8 material:

0.176g of Zn (CH) is weighed₃COO)₂And 0.350g of polyvinylpyrrolidone (PVP) dissolved in 25mL of methanol to give solution A; dissolving 0.263g of 2-methylimidazole in 25mL of methanol to obtain a solution B; mixing the solution A and the solution B at 0 ℃, stirring for 2h, standing at 25 ℃ for 20h, collecting the precipitate, washing with methanol for 3 times, and vacuum drying for 12h to obtain the final product.

Preparing a black porous ZnO material:

s1, placing the prepared ZIF-8 material in a high-temperature muffle furnace, heating to 580 ℃ at a heating rate of 6 ℃/min, and then preserving heat for 3.5 hours to obtain white porous ZnO powder;

s2, mixing the white porous ZnO material prepared in the step S1 and NaBH₄Uniformly mixing, wherein the white porous ZnO material and NaBH₄The mass ratio of the ZnO powder to the black powder is 1:1.8, annealing treatment is carried out for 1.5h at 350 ℃ in nitrogen atmosphere, cooling to room temperature, washing with water and ethanol for 3 times respectively, and vacuum drying is carried out for 12h at 60 ℃ to obtain the black porous ZnO powder.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.