A preparation method and application of an oxygen vacancy type crystal-amorphous TiO 2 surface enhanced Raman spectroscopy substrate

Abstract

The present invention discloses a preparation method and application of an oxygen vacancy type crystal-amorphous TiO2 surface enhanced Raman spectroscopy substrate. The preparation method includes: (1) mixing an oxygen vacancy type TiO2 solid powder and a borohydride powder according to a mass ratio of 2-3:1 and grinding; (2) transferring the ground mixture to a tube furnace and carrying out a heating reaction under the action of a protective gas; (3) cleaning and drying the obtained reaction product to obtain an oxygen vacancy type crystal-amorphous TiO2 surface enhanced Raman spectroscopy substrate. The present invention introduces a partial amorphous structure into the porous TiO2 nanostructure containing oxygen vacancies by using borohydride, thereby obtaining an oxygen vacancy type crystal-amorphous TiO2 surface enhanced Raman spectroscopy substrate. In addition, the substrate has SERS activity and anti-interference ability, and can realize the trace detection of chloramphenicol in an aqueous environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterial preparation, and specifically relates to a preparation method of an oxygen vacancy type crystal-amorphous TiO 2 surface enhanced Raman spectroscopy substrate and its application in the detection of chloramphenicol in water environment. Background Art

[0002] Surface enhanced Raman spectroscopy (SERS) technology is a highly sensitive "fingerprint recognition" detection method, and it has been developed and applied to a certain extent in the fields of material analysis, environmental monitoring, pharmaceutical detection, etc. Among them, designing and developing a fast, accurate, efficient, and highly sensitive SERS active substrate material is one of the most important hot research directions in the current research field. TiO 2 is considered to be one of the semiconductor nanomaterials that are economical, practical, and have great potential for SERS development. It has a wide bandgap and shows very flexible tunability in terms of structure and activity. However, as is well known, the intrinsic SERS activity of TiO 2 is relatively low, and its SERS performance needs to be improved through further regulation of the structure-activity relationship. This work has always been one of the most popular research contents in the field of SERS substrates.

[0003] The introduction of oxygen vacancies is a typical method for optimizing the TiO 2 nanostructure. The synthesis method has been reported in the literature [Xu Y, Wu S, Wan P, et al. RSC Advances, 2017, 7, 32461.]. In addition, the research on applying oxygen vacancy type TiO 2 nanomaterials to SERS substrates has also attracted people's attention, such as [Zheng X, Ren F, Zhang S, et al. ACS Applied Surface Science, 2017, 9(16), 14534-14544.]. The existing research on oxygen vacancy type TiO 2 nanoactive substrates mainly focuses on optimizing the bandgap structure and SERS activity of TiO 2 by introducing oxygen vacancies during the synthesis process and directly applying it to SERS substrates. However, it is difficult to achieve its practical application by only focusing on the regulation of structure and sensitivity, and the work of performing local amorphization treatment on the basis of oxygen vacancy type TiO 2 nanomaterials and applying it to practical research has not been reported yet. Since performing local amorphization treatment on oxygen vacancy type TiO 2 nanomaterials can further optimize the bandgap structure, enhance the SERS activity, and improve the anti-interference ability, thereby realizing the accurate analysis of actual SERS detection, which is of great significance for expanding the practicality of SERS substrates.

[0004] In recent years, the bacteriostatic broad-spectrum antibiotic chloramphenicol has been widely present in various water environments, causing a certain degree of pollution to the ecological environment. As is well known, residual chloramphenicol in the environment can induce the generation of drug-resistant bacteria or resistance genes, and the persistent residues of these drug-resistant bacteria or resistance genes in the environment are often more harmful to the environment than chloramphenicol itself. In addition, chloramphenicol ingested by people through different channels will accumulate in the human body, ultimately leading to diseases such as bone marrow suppression, leukemia, and kidney damage. Due to the large and frequent use of chloramphenicol, it has seriously endangered human health and the ecological environment. Therefore, there is an urgent need for an efficient, sensitive, and rapid detection method for trace chloramphenicol. The SERS technology is highly efficient, sensitive, and has great application potential for the detection of trace chloramphenicol. This technology can not only avoid the complex pre-enrichment process in other detection methods but also accurately identify chloramphenicol without destroying its molecular structure. Therefore, how to overcome the deficiencies in aspects such as SERS sensitivity and anti-interference ability has great development potential in both the basic research and practical applications of trace chloramphenicol detection. Summary of the Invention

[0005] The object of the present invention is to overcome the deficiencies in aspects such as SERS sensitivity and anti-interference ability in the prior art, and construct an oxygen vacancy type crystal-amorphous TiO 2 surface-enhanced Raman spectroscopy substrate, and explore the promoting effect on the improvement of SERS ability after local amorphization treatment based on the oxygen vacancy TiO 2 nanostructure, so as to achieve the efficient SERS detection of trace chloramphenicol in actual water environments.

[0006] In order to achieve the above invention object, the present invention provides the following technical solutions:

[0007] A preparation method of an oxygen vacancy type crystal-amorphous TiO 2 surface-enhanced Raman spectroscopy substrate, comprising the following steps:

[0008] (1) Mix the oxygen vacancy type TiO 2 solid powder and the borohydride powder according to a mass ratio of 2-3:1, and grind them;

[0009] (2) Transfer the ground mixture in step (1) to a tubular furnace and carry out a heating reaction under the condition of a protective gas;

[0010] (3) Wash and dry the obtained reaction product to obtain an oxygen vacancy type crystal-amorphous TiO 2 surface-enhanced Raman spectroscopy substrate.

[0011] Further, in step (1), the grinding time is 20 - 30 minutes, and the particle size of the mixture after grinding is 80 - 120 nm.

[0012] Further, in step (1), the oxygen vacancy type TiO 2 is a nanoscale porous structure.

[0013] Further, the borohydride is an alkali metal-containing borohydride, including sodium borohydride, potassium borohydride, and lithium borohydride.

[0014] Further, in step (2), the heating reaction means first maintaining the temperature at 380 - 420 °C for 1 - 2 hours, and then increasing the temperature at a heating rate of 5 - 10 °C / min; the protective gas is argon or a mixture of hydrogen and argon.

[0015] Further, in step (3), the cleaning means repeatedly cleaning 3 times with deionized water and alcohol, and the drying means drying in an oven at 60 - 80 °C for 12 - 24 hours.

[0016] The second object of the present invention is to provide an oxygen vacancy type crystal-amorphous TiO 2 surface enhanced Raman spectroscopy substrate prepared by the above preparation method.

[0017] The third object of the present invention is to provide the application of the above oxygen vacancy type crystal-amorphous TiO 2 surface enhanced Raman spectroscopy substrate for trace detection of chloramphenicol in water environment.

[0018] The specific trace detection process is as follows: Disperse the oxygen vacancy type crystal-amorphous TiO 2 surface enhanced Raman spectroscopy substrate in the chloramphenicol solution to be measured, shake at room temperature for 12 hours to obtain a mixture; take 1 mL of the mixture and drop it on the cleaned glass slide, and use a Raman spectrometer to perform SERS detection after natural drying.

[0019] The present invention designs and constructs an oxygen vacancy type crystal-amorphous TiO 2 surface enhanced Raman spectroscopy substrate, conducts detailed morphology, structure, and performance characterization on it, explores the influence of local amorphous treatment on the SERS activity based on the oxygen vacancy TiO 2 nanostructure, and applies it to the efficient SERS detection of trace chloramphenicol in the actual water environment. The present invention has the advantages of high activity, high selectivity, high sensitivity, high anti-interference ability, low cost, fast and efficient, etc., and is expected to be widely used in the fields of biomedicine, environmental detection, food safety, etc.

[0020] The beneficial effects of the present invention are as follows:

[0021] (1) The preparation method of the present invention is simple, with low cost and mild experimental conditions. By fully mixing the oxygen vacancy type TiO 2 nanomaterials with borohydride and subjecting them to one-step calcination, a partial amorphous structure can be introduced into the crystal structure, effectively improving the photoinduced charge transfer efficiency. Through local amorphization treatment, the present invention further regulates the internal structure of the oxygen vacancy type TiO 2 to effectively improve its SERS ability.

[0022] (2) The target product of the present invention exhibits excellent SERS activity, anti-interference ability, and specific recognition ability, meeting the basic conditions for SERS detection of chloramphenicol in practical applications. Through the regulation of the structure-activity relationship of TiO 2 , the present invention broadens the application scope of non-noble metal SERS technology and also brings new ideas for the design of other non-noble metal SERS substrates.

[0023] (3) By performing local amorphization treatment on the basis of the oxygen vacancy TiO 2 nanostructure, the present invention optimizes the band gap structure of TiO 2 , thereby improving the SERS activity and anti-interference ability of the substrate, and enabling trace detection of chloramphenicol in water environment. The preparation method of this oxygen vacancy type crystal-amorphous TiO 2 surface enhanced Raman spectroscopy substrate brings new ideas for improving the SERS performance of other non-noble metal materials.

[0024] (4) The substrate prepared by the present invention is simple to prepare, conducive to mass production, laying a solid foundation for future practical applications, and is expected to be widely used in the fields of biomedicine, environmental detection, food safety, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0026] Figure 1 FIG. is the scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the oxygen vacancy type crystal-amorphous TiO 2 nanomaterials prepared in Example 1:

[0027] Figure 2 FIG. is the high-resolution transmission electron microscope (HRTEM) image and the corresponding selected area fast Fourier transform (FFT) micrograph of the oxygen vacancy type crystal-amorphous TiO 2 nanomaterials prepared in Example 1;

[0028] Figure 3 FIG. is the Raman spectrum of the oxygen vacancy type crystal-amorphous TiO 2 nanomaterials prepared in Example 1;

[0029] Figure 4 is the XPS fine spectrum of the oxygen vacancy type crystal-amorphous TiO 2 nanomaterials prepared in Example 1;

[0030] Figure 5 is the SERS spectrum of the detection of chloramphenicol in actual water samples with different concentrations using the oxygen vacancy type crystal-amorphous TiO 2 nanomaterials as the SERS substrate. Detailed implementation mode

[0031] The present invention will be further described below in conjunction with embodiments, but the present invention is not limited to the following embodiments.

[0032] The preparation method of the oxygen vacancy type porous TiO 2 nanostructure in the present invention is known. For example, the oxygen vacancy type porous TiO 2 nanostructure can be prepared with reference to the literature [Xu Y, Wu S, Wan P, et al. RSC Advances, 2017, 7, 32461.]. Specific preparation steps: Add 0.05 mol of titanium sulfate and 0.05 mol of sodium chloride to 60 mL of deionized water. After stirring for 30 minutes, transfer the transparent solution to a high-pressure reactor and heat it at 120 °C for 12 hours with a heating rate of 5 °C / min. After washing and drying the obtained product, calcine it at 300 °C for 5 hours.

[0033] Example 1

[0034] (1) Mix the oxygen vacancy type TiO 2 solid powder and sodium borohydride powder at a mass ratio of 2:1 at room temperature, and grind the mixture thoroughly for 20 minutes. In the present invention, grinding means mixing powdery solid particles in a porcelain mortar (or made of materials such as glass, agate, etc.), and the particle size after grinding is about 80-120 nm;

[0035] (2) Transfer the mixture obtained in step (1) to a tubular furnace and carry out a heating reaction under the condition of a protective gas, that is, keep it at 380 °C for 1 hour and then heat it with a heating rate of 5 °C / minute, and the protective gas is argon;

[0036] (3) Collect the reaction product obtained in step (2), wash it repeatedly 3 times with deionized water and alcohol, and dry it in an oven at 60 °C for 12 hours to obtain the surface enhanced Raman spectroscopy substrate of the oxygen vacancy type crystal-amorphous TiO 2 ;

[0037] As Figure 1 shown is the oxygen vacancy type crystal-amorphous TiO prepared in Example 1 2Scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the nanomaterial: Among them Figure 1 a in it is the SEM image, Figure 1 b in it is the TEM image. It shows that the oxygen vacancy type crystal-amorphous TiO 2 nanomaterial is a porous nanosphere structure aggregated by a large number of small particles, and the size of a single nanosphere is about 80-120 nm.

[0038] As Figure 2 shown is the high-resolution transmission electron microscope (HRTEM) image and the corresponding selected area fast Fourier transform (FFT) micrograph of the oxygen vacancy type crystal-amorphous TiO 2 nanomaterial prepared in Example 1: Among them Figure 2 a in it is the HRTEM image. The area circled by the white solid line in the image is the amorphous region, and the area outside the white solid line is the crystalline region; Figure 2 b and c in it are the enlarged images of the randomly selected crystalline (region I) and amorphous (region II) respectively; Figure 2 d and e in it are the FFT images corresponding to the crystalline and amorphous regions respectively. It can be obtained from Figure 2 it that the oxygen vacancy type crystal-amorphous TiO 2 nanomaterial prepared in this application shows a coexisting structure of crystalline and amorphous with rich vacancies.

[0039] As Figure 3 shown is the Raman spectrum of the oxygen vacancy type crystal-amorphous TiO 2 nanomaterial prepared in Example 1; it can be seen from the figure that the oxygen vacancy type crystal-amorphous TiO 2 nanomaterial belongs to the anatase phase.

[0040] As Figure 4 shown is the XPS fine spectrum of the oxygen vacancy type crystal-amorphous TiO 2 nanomaterial prepared in Example 1: Among them Figure 4 a in it is O1s, and b in the figure is Ti 2p. It shows that the oxygen vacancy content in the oxygen vacancy type crystal-amorphous TiO 2 nanomaterial is rich, and Ti 3+ is formed.

[0041] Using the surface-enhanced Raman spectroscopy substrate of the above-prepared oxygen vacancy type crystal-amorphous TiO 2 for Raman detection, the specific process is as follows:

[0042] (1) Prepare a glass slide, clean it and set it aside;

[0043] (2) Prepare different concentrations (10 -4 -10 -8The chloramphenicol solution to be measured of (M), wherein the solvent is made by mixing the actual water sample (Dongpu Reservoir in Hefei, Anhui) and alcohol in a ratio of 1:1;

[0044] (3) Disperse 5 mg of the oxygen vacancy type crystal - amorphous TiO 2 surface - enhanced Raman spectroscopy substrate in 10 mL of the chloramphenicol solution to be measured obtained in step (2), and shake at room temperature for 12 hours;

[0045] (4) Take 1 mL of the mixture obtained in step (3) and drop it on the glass slide cleaned in step (1). After natural drying, perform SERS detection using a Raman spectrometer.

[0046] The detection results are as Figure 5 shown, indicating that the oxygen vacancy type crystal - amorphous TiO 2 nanomaterials prepared by the present invention exhibit excellent SERS activity, have good detection ability for chloramphenicol in the actual water environment, and the detection limit is as low as 10 -8 M.

[0047] Example 2

[0048] (1) Mix the oxygen vacancy type TiO 2 solid powder and lithium borohydride powder at a mass ratio of 3:1 at room temperature, and grind the mixture thoroughly for 30 minutes. In the present invention, grinding means mixing powdery solid particles in a porcelain mortar, and the particle size after grinding is about 80 - 120 nm;

[0049] (2) Transfer the mixture obtained in step (1) to a tubular furnace, and keep it at 400 °C for 1 hour. The heating rate is 5 °C / minute, and the protective gas is a mixture of hydrogen (volume ratio 5%) and argon (volume ratio 95%);

[0050] (3) Collect the reaction product obtained in step (2), wash it repeatedly 3 times with deionized water and alcohol, and then dry it in an oven at 60 °C for 24 hours to obtain the oxygen vacancy type crystal - amorphous TiO 2 surface - enhanced Raman spectroscopy substrate;

[0051] (4) Prepare a glass slide, clean it and set it aside for later use;

[0052] (5) Prepare chloramphenicol solutions to be measured with different concentrations (10 -4 -10 -8 M), and the solvent is made by mixing the actual water sample (Dongpu Reservoir in Hefei, Anhui) and alcohol in a ratio of 1:1;

[0053] (6) Disperse 5 mg of the oxygen vacancy type crystal - amorphous TiO 2The surface-enhanced Raman spectroscopy substrate is dispersed in 10 mL of the chloramphenicol solution to be measured obtained in step (5), and shaken at room temperature for 12 hours;

[0054] (7) Take 1 mL of the mixture obtained in step (6) and drop it on the glass slide cleaned in step (4). After natural drying, use a Raman spectrometer for SERS detection.

[0055] Example 3

[0056] (1) Mix the oxygen vacancy type TiO 2 solid powder and potassium borohydride powder at a mass ratio of 2.5:1 at room temperature, and thoroughly grind the mixture for 30 minutes. In the present invention, grinding refers to mixing powdered solid particles in a vitreous mortar, and the particle size after grinding is about 80 - 120 nm;

[0057] (2) Transfer the mixture obtained in step (1) to a tubular furnace and keep it at 420 °C for 1 hour. The heating rate is 10 °C / minute, and the protective gas is argon;

[0058] (3) Collect the reaction product obtained in step (2), wash it repeatedly 3 times with deionized water and alcohol, and dry it in an oven at 80 °C for 18 hours to obtain the oxygen vacancy type crystal - amorphous TiO 2 surface-enhanced Raman spectroscopy substrate;

[0059] (4) Prepare a glass slide, clean it and set it aside for later use;

[0060] (5) Prepare chloramphenicol solutions to be measured with different concentrations (10 -4 -10 -8 M), and the solvent is made by mixing actual water samples (Dongpu Reservoir in Hefei, Anhui) and alcohol in a ratio of 1:1;

[0061] (6) Disperse 5 mg of the oxygen vacancy type crystal - amorphous TiO 2 surface-enhanced Raman spectroscopy substrate in 10 mL of the chloramphenicol solution to be measured obtained in step (5), and shake it at room temperature for 12 hours;

[0062] (7) Take 1 mL of the mixture obtained in step (6) and drop it on the glass slide cleaned in step (4). After natural drying, use a Raman spectrometer for SERS detection.

[0063] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. Preparation method of oxygen vacancy type crystal-amorphous TiO 2 surface enhanced Raman spectroscopy substrate It is characterized in that: It includes the following steps: (1) Mix the oxygen vacancy type TiO 2 solid powder and the borohydride powder in a mass ratio of 2-3:1, and grind; the borohydride is an alkali metal-containing borohydride, including sodium borohydride, potassium borohydride or lithium borohydride; (2) Transfer the ground mixture in step (1) to a tubular furnace and carry out a heating reaction under the action of a protective gas; (3) Wash and dry the obtained reaction product to obtain an oxygen vacancy type crystal - amorphous TiO 2 surface - enhanced Raman spectroscopy substrate.

2. The preparation method according to claim 1, It is characterized in that: In step (1), the grinding time is 20 - 30 minutes, and the particle size of the ground mixture is 80 - 120 nm.

3. The preparation method according to claim 1, It is characterized in that: The oxygen vacancy type TiO described in step (1) 2 is a nanoscale porous structure.

4. The preparation method according to claim 1, It is characterized in that: The heating reaction in step (2) means first keeping the temperature at 380 - 420 °C for 1 - 2 hours, and then increasing the temperature at a heating rate of 5 - 10 °C / minute; the protective gas is argon or a mixture of hydrogen and argon.

5. The preparation method according to claim 1, It is characterized in that: The cleaning in step (3) means repeatedly cleaning 3 times with deionized water and alcohol, and the drying means drying in an oven at 60 - 80 °C for 12 - 24 hours.

6. The oxygen vacancy type crystal-amorphous TiO surface enhanced Raman spectroscopy substrate prepared by the preparation method according to any one of claims 1-5 2 ​ 7. Application of the oxygen vacancy type crystal-amorphous TiO 2 surface enhanced Raman spectroscopy substrate, It is characterized in that: It is used for trace detection of chloramphenicol in the water environment.

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