A high-performance photoelectrochemical sensor and a preparation method and application thereof

Abstract

The application relates to the field of food safety and environmental analysis and detection technology, and particularly discloses a high-performance photoelectrochemical sensor based on a Bi2WO6 nanoflower / Ti3C2-MXene three-dimensional / two-dimensional heterojunction as well as a preparation method and application thereof. The sensor comprises a conductive substrate electrode and a photoelectric active heterojunction material layer constructed on the surface of the conductive substrate electrode. The photoelectric active heterojunction material layer is constructed through a space confinement strategy, so that the Bi2WO6 nanoflower is in-situ and uniformly grown on the multilayer Ti3C2-MXene nanosheet, and a composite structure in close contact is formed. The sensor has a wide linear detection range (0.001-100 nM) and an ultralow detection limit of 0.3 pM for tetracycline antibiotics (preferably tetracycline hydrochloride), has excellent analysis performance, is simple and convenient to operate, is low in cost, and is suitable for rapid and sensitive detection of trace antibiotic residues in food safety and environment.

Description

Technical Field

[0001] This invention belongs to the field of food safety and environmental analysis and detection technology, specifically relating to a high-performance photoelectrochemical sensor based on Bi2WO6 nanoflower / Ti3C2-MXene three-dimensional / two-dimensional heterojunction, its preparation method and application, especially suitable for rapid and sensitive detection of trace tetracycline antibiotic residues. Background Technology

[0002] The widespread use of antibiotics in livestock farming and food processing has led to significant problems related to their residues in food products and the environment. The long-term presence of antibiotic residues not only results in bioaccumulation but also promotes the spread of antibiotic-resistant microorganisms, posing a serious threat to food safety and public health. Therefore, developing efficient and sensitive methods for monitoring antibiotic residues is of great importance for the safety detection of food matrices and environmental monitoring.

[0003] Traditional methods for analyzing antibiotic residues include high-performance liquid chromatography (HPLC), mass spectrometry (MS), and enzyme-linked immunosorbent assay (ELISA). While these methods can provide reliable quantitative results, they rely on complex and sophisticated instruments, involve cumbersome procedures, have long analysis times, and are costly, which limits their widespread application in rapid and on-site detection.

[0004] In contrast, photoelectrochemical sensing technology, as an emerging detection technology, has received widespread attention in recent years due to its significant advantages such as high sensitivity, ease of operation, rapid response, and low cost, particularly in fields like food safety analysis and environmental monitoring. The core performance of photoelectrochemical sensors depends on the photoelectric conversion efficiency and stability of the photoactive materials. However, existing photoelectrochemical sensing materials generally suffer from problems such as insufficient interfacial coupling, high interfacial resistance, easy recombination of photogenerated carriers, and insufficient active sites due to the tendency of nanomaterials to aggregate, severely restricting the improvement of the analytical performance of photoelectrochemical sensors.

[0005] Therefore, developing photoactive materials with high photoelectric conversion efficiency, stable interface structure and abundant active sites to construct high-performance photoelectrochemical sensors has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing photoelectrochemical sensing materials, such as insufficient interfacial coupling, high interfacial resistance, easy recombination of photogenerated carriers, and insufficient active sites due to the easy aggregation of nanomaterials. This invention provides a Bi2WO6 nanoflower / Ti3C2-MXene 3D / 2D heterojunction photoelectrochemical sensor constructed based on a spatial confinement strategy. This sensor exhibits excellent photoelectric conversion efficiency and stability, enabling highly sensitive and wide linear range detection of tetracycline antibiotics. It is simple to operate, low in cost, and suitable for rapid on-site detection.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A high-performance photoelectrochemical sensor includes a conductive substrate electrode and a photoelectroactive heterojunction material layer constructed on the surface of the conductive substrate electrode. The photoelectric active heterojunction material layer comprises a three-dimensional / two-dimensional heterostructure formed by the composite of Bi2WO6 nanoflowers and Ti3C2-MXene nanosheets.

[0008] In a preferred example, the three-dimensional / two-dimensional heterostructure is constructed through a spatial confinement strategy, enabling Bi2WO6 nanoflowers to grow uniformly in situ on multilayer Ti3C2-MXene nanosheets, forming a composite structure with a tightly coupled interface. This tightly coupled interface can significantly reduce the interfacial charge transfer resistance, promote the separation and transport of photogenerated carriers, and improve the photoelectrochemical response performance.

[0009] In a preferred example, the average size of the Bi2WO6 nanoflowers is 0.5 μm, which is more than 66% smaller than that of Bi2WO6 nanoflowers grown without a spatial confinement strategy. The spatial confinement effect provided by the multilayer Ti3C2-MXene nanosheets can effectively regulate the nucleation and growth process of Bi2WO6 nanoflowers, inhibit their aggregation, and increase the exposed area of ​​active sites.

[0010] In a preferred example, the Ti3C2-MXene comprises 5%, 10%, or 15% by mass in the heterojunction material. A mass fraction of 10% is preferred, as this ratio provides the optimal photoelectric conversion efficiency and charge transport performance of the heterojunction.

[0011] Based on a general inventive concept, another object of the present invention is to provide a method for preparing the above-mentioned high-performance photoelectrochemical sensor, comprising the following steps: (1) Preparation of Ti3C2-MXene powder The LiF and HCl solution was stirred in an ice-water bath for 30 min, Ti3AlC2 powder was added, and the mixture was transferred to an oil bath at 50 °C and stirred continuously for 48 h. The product Ti3C2-MXene powder was collected by centrifugation. (2) Preparation of precursor solution Mix 2 mM Bi(NO3)3 solution and 1 mM Na2WO4 solution evenly and stir for 30 min to obtain the precursor solution; (3) Preparation of Bi2WO6 / MXene complex Ti3C2-MXene powder was added to the precursor solution and hydrothermally reacted at 160℃ for 24 h. The product was collected by centrifugation, washed, and dried to obtain the Bi2WO6 / MXene complex. (4) Sensor fabrication The Bi2WO6 / MXene composite was first dispersed in ultrapure water to form a dispersion, which was then drop-coated onto the surface of a pretreated conductive substrate electrode. After natural drying at room temperature, a high-performance photoelectrochemical sensor was obtained.

[0012] In a preferred example, in step (1), the mass ratio of LiF to Ti3AlC2 powder is 3:2, and the concentration of HCl solution is 8M-10M.

[0013] In a preferred example, in step (4), the conductive substrate electrode is an L-shaped glassy carbon electrode (5 mm in diameter), which has good conductivity and stability and can provide a stable supporting substrate for the heterojunction material layer; the pretreatment steps are: polishing with 0.05 μm alumina polishing slurry, and ultrasonic cleaning in ethanol and ultrapure water in sequence; the concentration of the dispersion is 3.0 mg / mL-5.0 mg / mL, and the drop volume is 10 μL-20 μL.

[0014] The aforementioned high-performance photoelectrochemical sensor is used for the detection of tetracycline antibiotics such as tetracycline, tetracycline hydrochloride, oxytetracycline, and doxycycline, wherein the tetracycline antibiotic is preferably tetracycline hydrochloride.

[0015] In a preferred example, a method for detecting tetracycline antibiotics includes the following steps: (1) The sensor is placed in a detection system containing 0.1M Na2SO4 supporting electrolyte. A three-electrode system is used, with the sensor as the working electrode, a platinum wire as the counter electrode, and a saturated calomel electrode as the reference electrode. (2) Under illumination, apply a set bias voltage of 0.3V to the working electrode; (3) Add different concentrations of target analyte solutions to the detection system, stir for 3 minutes to mix them evenly, measure the photocurrent response of the system using the chronoamperometry method, and quantitatively detect the target analyte based on the photocurrent change.

[0016] The linear range of this detection method is 0.001 nM to 100 nM, and the detection limit is 0.3 pM (signal-to-noise ratio S / N=3).

[0017] Compared with the prior art, the advantages and positive effects of the present invention are as follows: 1. This invention constructs a three-dimensional / two-dimensional heterojunction of Bi2WO6 nanoflowers / Ti3C2-MXene through a spatial confinement strategy, so that Bi2WO6 and MXene form a tightly coupled interface structure, which significantly reduces the interface charge transfer resistance, effectively promotes the separation and transport of photogenerated carriers, improves photoelectric conversion efficiency, and thus enhances the photoelectrochemical response signal.

[0018] 2. The spatial confinement effect provided by multilayer MXene can effectively regulate the nucleation and growth of Bi2WO6 nanoflowers, inhibit their aggregation, significantly reduce the size of Bi2WO6 nanoflowers, increase the exposed area of ​​active sites, and promote the reduction of dissolved oxygen to generate superoxide radicals (•O2). − This free radical, as the main active species, participates in the oxidation reaction of the target analyte, enhancing the amplification effect of the sensing signal.

[0019] 3. The photoelectrochemical sensor constructed in this invention has a wide linear detection range (0.001 nM-100 nM) and an ultra-low detection limit of 0.3 pM for tetracycline antibiotics such as tetracycline hydrochloride. Its overall performance is superior to most reported photoelectrochemical sensors and can meet the needs of trace antibiotic residue detection.

[0020] 4. The preparation method of the present invention is simple, convenient to operate, and low in cost. It does not require complex and precision equipment and is easy to mass-produce. The detection method of the sensor is simple to operate and has a fast response. It is suitable for rapid on-site detection and has broad application prospects in the fields of food safety and environmental monitoring.

[0021] 5. The sensor of this invention exhibits excellent stability and selectivity, maintains good detection performance even in complex matrices, and has strong anti-interference capabilities, providing important theoretical and technical support for the development of efficient and sensitive environmental detection and biosensing technologies. Attached Figure Description

[0022] Figure 1 In the image, (a) is a SEM image of Ti3C2-MXene; (b) is a SEM image of Bi2WO6; and (c) is a SEM image of Bi2WO6 / MXene.

[0023] Figure 2 In the figure, (a) shows the transient photocurrent response curves of Bi2WO6, BM-5, BM-10 and BM-15; (b) shows the photocurrent comparison curves of BM-10 and Bi2WO6 electrodes with and without tetracycline hydrochloride.

[0024] Figure 3 In the figure, (a) shows the relationship between the photocurrent of the BM-10 electrode and the concentration of tetracycline hydrochloride; (b) shows the corresponding calibration curve. Figure 4 The results show the anti-interference test results of BM-10 in the presence of other antibiotics.

[0025] in, Figure 1 The layered structure of Ti3C2-MXene, the flower-like structure of pure Bi2WO6, and the uniform dispersion of Bi2WO6 nanoflowers on MXene in the heterojunction are clearly shown. Figure 2This demonstrates the differences in heterojunction photocurrent response with different MXene mass fractions and the specificity of BM-10 response to tetracycline hydrochloride; Figure 3 This provides the core data support for the sensor's quantitative detection of tetracycline hydrochloride. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments, test examples and performance test results. The raw materials and reagents used are all industrial-grade conventional products, and the equipment used are all conventional commercially available equipment in the fields of electrochemical detection and material preparation, without any special customization requirements.

[0027] In the embodiments / test examples of this invention, the photocurrent response was measured using a Shanghai Chenhua CHI 760E electrochemical workstation. The linear range and detection limit were calculated based on the photocurrent response data (the detection limit was calculated based on a signal-to-noise ratio of S / N=3). The L-shaped glassy carbon electrode, platinum wire electrode, and saturated calomel electrode used were conventional electrodes for electrochemical detection. The raw materials, such as Ti3AlC2 (MAX phase) powder, LiF, HCl, Bi(NO3)3, and Na2WO4, were all commercially available analytical grade products.

[0028] Example 1: Preparation of Bi2WO6 / MXene complex 1. Preparation of Ti3C2-MXene sample: In a polytetrafluoroethylene-lined reactor, add 3.0 g LiF and 40 mL of 9 M HCl solution, stir in an ice-water bath for 30 min; slowly add 2.0 g Ti3AlC2 powder, transfer to a 50 °C oil bath and stir for 48 h, collect the product by centrifugation to obtain Ti3C2-MXene sample.

[0029] 2. Preparation of precursor solution: Prepare 0.1 mol / L Bi(NO3)3 aqueous solution and 0.05 mol / L Na2WO4 aqueous solution, mix them at a molar ratio of Bi(NO3)3 to Na2WO4 of 2:1, and stir at room temperature for 30 min to obtain the precursor solution.

[0030] 3. Preparation of Bi2WO6 / MXene complex: Take appropriate amounts of Ti3AlC2-MXene powder and add them to the precursor solution to make the mass fractions of Ti3C2-MXene 5%, 10%, and 15%, respectively. After ultrasonic dispersion for 10 min, transfer them to a high-pressure reactor and hydrothermally react at 160℃ for 24 h. Collect the yellow precipitate by centrifugation, wash it three times with methanol, and dry it under vacuum at 60℃ for 8 h to obtain BM-5, BM-10, and BM-15 complexes, respectively.

[0031] Example 2: Fabrication of a photochemical sensor

[0032] 1. Electrode pretreatment: The L-shaped glassy carbon electrode was polished with 0.05μm alumina polishing slurry, ultrasonically cleaned in ethanol and ultrapure water for 10 min in sequence, and then air-dried at room temperature for later use.

[0033] 2. Sensor preparation: 4.0 mg of BM-5, BM-10 and BM-15 complexes were dispersed in 1 mL of ultrapure water and sonicated for 30 min to obtain a uniform dispersion. 15 μL of the dispersion was drop-coated onto the surface of the pretreated glassy carbon electrode and dried at room temperature to obtain BM-5 sensor, BM-10 sensor and BM-15 sensor respectively.

[0034] Comparative Example 1: Fabrication of a pure Bi2WO6 sensor Pure Bi2WO6 powder (without Ti3C2-MXene) was prepared according to the steps of Example 1, and then a pure Bi2WO6 sensor was prepared according to the steps of Example 2 as a comparison.

[0035] Comparative Example 2: Fabrication of the MXene Sensor

[0036] Take 4.0 mg of Ti3C2-MXene sample, disperse it in 1 mL of ultrapure water, and sonicate for 30 min to obtain a dispersion; take 15 μL of the dispersion and drop it onto the surface of the pretreated glassy carbon electrode, and let it dry naturally at room temperature to obtain an MXene sensor as a control.

[0037] Test Example 1: Sensor Photocurrent Response Performance Test

[0038] A three-electrode system was used, with the sensors prepared in each embodiment and comparative example as the working electrode, a platinum wire as the counter electrode, and a saturated calomel electrode as the reference electrode. Transient photocurrent response tests were conducted in a 0.1M Na₂SO₄ supporting electrolyte with a bias voltage of 0.3V. The results are as follows: Figure 2 As shown in (a) of the diagram.

[0039] The test results show that the MXene sensor in Comparative Example 2 has a weak photocurrent response; the pure Bi2WO6 sensor in Comparative Example 1 has a photocurrent intensity of 48.3 nA; the BM-5, BM-10, and BM-15 sensors in Example 2 have photocurrent intensities of 186.2 nA, 262.5 nA, and 215.8 nA, respectively. Among them, the BM-10 sensor has the highest photocurrent intensity, which is 5.43 times higher than that of the pure Bi2WO6 sensor. This indicates that the heterojunction formed by Bi2WO6 and Ti3C2-MXene can significantly improve the photoelectric conversion efficiency.

[0040] Test Example 2: Sensor Response Specificity Test to Tetracycline Hydrochloride

[0041] Using the BM-10 sensor and a pure Bi₂WO₆ sensor as test objects, the photocurrent response under the condition of 100 nM tetracycline hydrochloride was tested in 0.1 M Na₂SO₄ supporting electrolyte with a bias voltage of 0.3 V and the results are as follows. Figure 2 As shown in (b) of the diagram.

[0042] Test results show that after introducing 100 nM tetracycline hydrochloride, the photocurrent of the BM-10 sensor significantly decreased from 262.5 nA to 53.4 nA, indicating a noticeable change in photocurrent; while the photocurrent of the pure Bi2WO6 sensor only showed minor fluctuations, which are negligible. These results confirm that the BM-10 sensor exhibits excellent response specificity to tetracycline hydrochloride, enabling the detection of target analytes through changes in photocurrent.

[0043] Test Example 3: Performance Test of Sensor for Quantitative Detection of Tetracycline Hydrochloride

[0044] Using the BM-10 sensor as the test object, a three-electrode system was employed. In a 0.1M Na₂SO₄ supporting electrolyte, a bias voltage of 0.3V was applied, and different concentrations of tetracycline hydrochloride solutions (0.001nM, 0.01nM, 0.1nM, 1nM, 10nM, 50nM, 100nM) were added sequentially. After stirring for 3 minutes, the photocurrent response was recorded. The results are as follows: Figure 3 As shown in (a); a calibration curve was established based on the relationship between photocurrent change and tetracycline hydrochloride concentration, and the results are as follows. Figure 3 As shown in (b) of the diagram.

[0045] Test results show that the photocurrent response of the BM-10 sensor gradually decreases with increasing tetracycline hydrochloride concentration; within the concentration range of 0.001-10 nM, the photocurrent exhibits a good linear relationship with the concentration, with the linear equation being y=13.77x-232.83 (R0). 2 =0.992); in the concentration range of 10-100 nM, the linear equation is y=0.31x-96.33 (R = 0.992). 2 =0.995); the detection limit of the sensor is calculated to be 0.3 pM (S / N=3), demonstrating excellent quantitative detection performance.

[0046] Test Example 4: Sensor Anti-interference Performance Test

[0047] Using the BM-10 sensor as the test object, other antibiotics at 10 times the concentration of tetracycline were added as interfering substances during the tetracycline test. The anti-interference test results are as follows: Figure 4 The results show that, in the presence of other antibiotics, the sensor's detection error for 10 nM tetracycline hydrochloride is ≤5%, indicating that the sensor of the present invention has good anti-interference ability.

[0048] The above embodiments are merely preferred embodiments of the present invention. Any simple modifications, alterations, and substitutions made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A high-performance photoelectrochemical sensor, characterized in that, It includes a conductive substrate electrode and a photoelectric active heterojunction material layer constructed on the surface of the conductive substrate electrode; The photoelectric active heterojunction material layer comprises a three-dimensional / two-dimensional heterostructure formed by the composite of Bi2WO6 nanoflowers and Ti3C2-MXene nanosheets.

2. The high-performance photoelectrochemical sensor according to claim 1, characterized in that, The three-dimensional / two-dimensional heterostructure is constructed through a spatial confinement strategy, enabling Bi2WO6 nanoflowers to grow uniformly in situ on multilayer Ti3C2-MXene nanosheets, forming a composite structure with a close contact interface. This composite structure can reduce the interfacial charge transfer resistance.

3. The high-performance photoelectrochemical sensor according to claim 1 or 2, characterized in that, The average size of the Bi2WO6 nanoflowers is 0.5 μm, which is more than 66% smaller than that of Bi2WO6 nanoflowers grown without spatial confinement strategy.

4. The high-performance photoelectrochemical sensor according to any one of claims 1 to 3, characterized in that, The mass fraction of Ti3C2-MXene in the heterojunction material is 5%, 10%, or 15%.

5. A method for preparing a high-performance photoelectrochemical sensor as described in any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Preparation of Ti3C2-MXene powder The LiF and HCl solution was stirred in an ice-water bath for 30 min, Ti3AlC2 powder was added, and the mixture was transferred to an oil bath at 50 °C and stirred continuously for 48 h. The product Ti3C2-MXene powder was collected by centrifugation. (2) Preparation of precursor solution Mix 2 mM Bi(NO3)3 solution and 1 mM Na2WO4 solution evenly and stir for 30 min to obtain the precursor solution; (3) Preparation of Bi2WO6 / MXene complex Ti3C2-MXene powder was added to the precursor solution and hydrothermally reacted at 160℃ for 24 h. The product was collected by centrifugation, washed, and dried to obtain the Bi2WO6 / MXene complex. (4) Sensor fabrication The Bi2WO6 / MXene composite was first dispersed in ultrapure water to form a dispersion, which was then drop-coated onto the surface of a pretreated conductive substrate electrode. After natural drying at room temperature, a high-performance photoelectrochemical sensor was obtained.

6. The preparation method according to claim 5, characterized in that, In step (1), the mass ratio of LiF to Ti3AlC2 powder is 3:2, and the concentration of HCl solution is 8M-10M.

7. The preparation method according to claim 5, characterized in that, In step (4), the conductive substrate electrode is an L-shaped glassy carbon electrode. The pretreatment steps are as follows: polishing with 0.05μm alumina polishing slurry, and ultrasonic cleaning in ethanol and ultrapure water in sequence; the concentration of the dispersion is 3.0mg / mL-5.0mg / mL, and the drop volume is 10μL-20μL.

8. An application of the high-performance photoelectrochemical sensor as described in any one of claims 1 to 4, characterized in that, This is used for the detection of tetracycline antibiotics such as tetracycline, tetracycline hydrochloride, oxytetracycline, and doxycycline, wherein the tetracycline antibiotic is preferably tetracycline hydrochloride.

9. The application according to claim 8, characterized in that, The detection method for tetracycline antibiotics includes the following steps: (1) The sensor is placed in a detection system containing 0.1M Na2SO4 supporting electrolyte. A three-electrode system is used, with the sensor as the working electrode, a platinum wire as the counter electrode, and a saturated calomel electrode as the reference electrode. (2) Under illumination, apply a set bias voltage of 0.3V to the working electrode; (3) Add different concentrations of target analyte solutions to the detection system, stir for 3 minutes to mix them evenly, measure the photocurrent response of the system using the chronoamperometry method, and quantitatively detect the target analyte based on the photocurrent change.

10. The application according to claim 9, characterized in that, The linear range of the detection method is 0.001 nM-100 nM, the detection limit is 0.3 pM, and the signal-to-noise ratio (S / N) is 3.

Images