A dioctyl phthalate molecular imprinting type photoelectrochemical sensor and a preparation method thereof

Abstract

The application discloses a preparation method of a photoelectrochemical sensor for high-sensitivity detection of dioctyl phthalate in environment and food. The sensor adopts a three-electrode system, wherein a working electrode is prepared by modifying an ITO conductive substrate with a Cu-T@C3N4 heterojunction composite material and combining a molecular imprinting technology. The composite material effectively reduces a TiO2 band gap and introduces oxygen vacancies by Cu2+ doping, combines a layered porous structure of g-C3N4 to form a three-dimensional conductive network, significantly enhances the material's visible light absorption capacity and photo-generated carrier separation efficiency, and thus effectively improves photoelectric conversion performance. In addition, the sensor combines a molecular imprinting recognition technology, takes dioctyl phthalate as a template molecule and o-phenylenediamine as a functional monomer, constructs a molecular imprinting polymer film with specific recognition sites on the electrode surface through an electropolymerization method, and realizes "lock-key" type high-selectivity recognition of the target molecule. The application also includes a construction process of the sensor and application of the sensor in detection of dioctyl phthalate. The method has the advantages of simple operation, rapid response, high sensitivity, good selectivity, simple instrument equipment and low cost, can effectively overcome technical bottlenecks such as complex pretreatment, expensive instrument and difficulty in on-site rapid detection of traditional chromatographic methods, and has important practical application value in the fields of environment monitoring and food safety.

Description

Technical Field

[0001] This invention belongs to the field of photoelectrochemical sensors and molecular imprinting technology, specifically relating to a dioctyl phthalate molecularly imprinted photoelectrochemical sensor and its preparation method. Background Technology

[0002] Plasticizers, widely used additives in polymer materials, have become a major environmental concern due to their environmental residues and migration. Phthalate esters are particularly prominent, continuously released from consumer products such as personal care products and textiles, and widely distributed in environmental media including air, soil, and even water, making their detection and remediation crucial. Phthalate esters (PAEs) mainly include dioctyl phthalate (DOP), dibutyl phthalate (DBP), and dimethyl phthalate (DMP). When interacting with materials, phthalate esters increase the distance between polymer chains, weakening intermolecular forces and improving material properties. Therefore, they are not linked by stable chemical bonds and are greatly affected by external conditions such as light, temperature increases, and repeated use, all of which accelerate their release into the environment. These esters then enter the human body through diet, inhalation, and skin contact, accumulating in the body. In particular, dioctyl phthalate may cause birth defects, cancer, and mutations after entering the human body. Due to its high similarity in chemical structure to endogenous estrogen, dioctyl phthalate can affect the endocrine system, thereby increasing the risk of endocrine diseases such as obesity and diabetes. Therefore, achieving highly sensitive detection of dioctyl phthalate is essential for public health and the prevention of environmental pollution.

[0003] In recent years, detection technologies for PAEs have developed rapidly. Commonly used methods for PAE detection include gas chromatography, gas chromatography-mass spectrometry, high-performance liquid chromatography, and liquid chromatography-tandem mass spectrometry. While these methods exhibit good linearity and high reliability, they generally rely on large, sophisticated instruments and have limitations such as complex sample pretreatment, time-consuming detection procedures, and the need for specialized operators, making it difficult to meet the needs of rapid on-site detection. In contrast, novel sensing technologies such as photoelectrochemical sensors offer advantages such as high selectivity, low detection limits, rapid response, and ease of operation, enabling rapid on-site detection without the need for large instruments, demonstrating significant application potential in market supervision and production site monitoring. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a method for preparing a molecularly imprinted photoelectrochemical sensor for detecting dioctyl phthalate. This method is simple to operate and easy to promote.

[0005] The problem this invention aims to solve is the dioctyl phthalate molecularly imprinted photoelectrochemical sensor prepared by the above-mentioned method. This sensor utilizes energy level hybridization between g-C3N4 and Cu²⁺-modified TiO2, effectively reducing the band gap of TiO2 by constructing a heterojunction structure. It is stable under specific conditions, significantly enhancing the material's absorption capacity for visible light and improving the sensor's sensitivity. Molecular imprinting technology has unique technical advantages in the specific recognition of target molecules. The synthesized molecularly imprinted polymers exhibit predictability and high selectivity for target molecules, specifically recognizing template molecules or structural analogs, demonstrating excellent selective recognition ability and sensing performance. Another technical problem this invention aims to solve is to provide applications for the above-mentioned dioctyl phthalate molecularly imprinted photoelectrochemical sensor. This sensor has significant advantages such as convenient operation, high sensitivity, good accuracy, simple equipment, and low cost.

[0006] Based on this, this invention employs a hydrothermal method to load Cu²⁺ onto the surface of TiO₂ to prepare a Cu-TiO₂ composite (Cu-T). Subsequently, Cu-T is composited with g-C₃N₄ to finally obtain the ternary composite material Cu-TiO₂@C₃N₄. The prepared Cu-T@C₃N₄ heterojunction material is then modified onto an ITO electrode, and combined with molecularly imprinted polymer recognition to construct a photoelectrochemical sensor. Utilizing the signal amplification and increased specific surface area of ​​nanomaterials, rapid and sensitive detection by the photoelectrochemical sensor is achieved, which is of great significance.

[0007] This invention optimizes the number of cycles in molecularly imprinted electropolymerization, the concentration ratio of the polymerization reaction solution (template molecule: functional monomer), elution time, and recognition time, obtaining the following optimal conditions: 35 electropolymerization cycles, a template molecule to functional monomer concentration ratio of 1:6, an elution time of 33 min, and a recognition time of 15 min. The dioctyl phthalate molecularly imprinted photoelectrochemical sensor MIP / Cu-T@C3N4 / ITO prepared under these optimal conditions exhibits excellent photoelectrochemical sensing performance.

[0008] The technical solution of this invention is as follows: A method for preparing a dioctyl phthalate molecularly imprinted photoelectrochemical sensor, characterized by comprising the following steps: (1) Add glacial acetic acid and copper chloride to a beaker and stir; (2) Add tetrabutyl titanate slowly to the solution in step (1) and stir until the reaction is complete to obtain solution A; (3) Transfer the A solution obtained in step (2) to a high-pressure reactor for reaction; (4) After the reaction vessel of step (3) has cooled naturally to room temperature, the reaction products are separated by centrifugation; (5) The precipitate obtained in step (4) is centrifuged and dried, and then dried at high temperature to obtain Cu-T material; (6) Add deionized water and hexadecyltrimethylammonium bromide to a beaker and stir in a water bath; (7) Add the Cu-T powder obtained in step (5) to the solution in step (6) and stir continuously to obtain solution B; (8) Add carbon nitride and deionized water to a beaker and sonicate to obtain solution C; (9) Slowly add the B solution obtained in step (8) to the C solution in step (8) and sonicate. (10) Centrifuge the solid mixture after the reaction in step (9); (11) The product washed in step (10) was placed in an evaporating dish and dried under vacuum to obtain Cu-T@C3N4 hybrid material; (12) Take the composite material obtained in step (11) and disperse it in DMF and sonicate it to obtain a uniformly dispersed suspension; (13) ITO conductive glass was ultrasonically treated with toluene, acetone, ethanol and ultrapure water respectively, and then placed in an oven to dry for further processing. (14) The Cu-T@C3N4 suspension obtained in step (12) is modified onto the surface of the ITO electrode and then subjected to infrared drying; (15) Electropolymerization of o-phenylenediamine and dioctyl phthalate on the electrode surface obtained in step (14); (16) The electrode obtained in step (15) is eluted with a mixed solution of methanol and acetic acid to obtain a dioctyl phthalate molecularly imprinted photoelectrochemical sensor. (17) The electrode obtained in step (16) is identified in a dioctyl phthalate solution.

[0009] As a preferred technical solution of this application, in step (1), the amount of glacial acetic acid used is 30 mL, the amount of copper chloride is 1.3 g, and the stirring time is 1 h.

[0010] As a preferred technical solution of this application, the amount of tetrabutyl titanate in step (2) is 17 mL and the stirring time is 1 h.

[0011] As a preferred technical solution of this application, the reaction temperature of the high-pressure reactor in step (3) is 200 °C and the reaction time is 18 h.

[0012] As a preferred technical solution of this application, in step (4), the product is washed with anhydrous ethanol and ultrapure water respectively, and then subjected to a temperature of 8000 rpm·min. -1 Centrifuge for 5 minutes, then centrifuge twice.

[0013] As a preferred technical solution of this application, the precipitate drying temperature in step (5) is 80 ℃ and the drying time is 12 h, while the drying temperature in the muffle furnace is 500 ℃ and the drying time is 2 h.

[0014] As a preferred technical solution of this application, in step (6), the amount of hexadecyltrimethylammonium bromide is 0.2g, the amount of deionized water added is 30 mL, and the water bath temperature is 40 ℃.

[0015] As a preferred technical solution of this application, the amount of Cu-T used in step (7) is 1 g.

[0016] As a preferred technical solution of this application, in step (8), the amount of carbon nitride used is 1.74 g, the amount of deionized water added is 20 mL, and the ultrasonic time is 1 h.

[0017] As a preferred technical solution of this application, the ultrasound time in step (9) is 1 h.

[0018] As a preferred technical solution of this application, step (10) is performed at 8000 rpm·min -1 Centrifuge for 5 min, then wash with anhydrous ethanol and ultrapure water respectively, and centrifuge at 8000 rpm·min. -1 Centrifuge for 5 minutes, then centrifuge twice.

[0019] As a preferred technical solution of this application, the precipitate drying temperature in step (11) is 80 ℃ and the drying time is 12 h.

[0020] As a preferred technical solution of this application, in step (12), 4 mg of Cu-T@C3N4 composite material is added to 1 mL of DMF.

[0021] As a preferred technical solution of this application, step (13) involves ultrasonicating with 15 mL of toluene, acetone, ethanol, and ultrapure water for 15 min in sequence, followed by drying in an oven at 60 °C.

[0022] As a preferred technical solution of this application, step (14) involves taking 10 μL of Cu-T@C3N4 dispersion and modifying it on a clean ITO electrode surface, followed by infrared drying.

[0023] As a preferred technical solution of this application, the electropolymerization method in step (15) is cyclic voltammetry, and the electropolymerization solution is an acetate-sodium acetate buffer solution (pH=4.2) containing 1 mM dioctyl phthalate and 6 mM o-phenylenediamine.

[0024] As a preferred technical solution of this application, the electrode eluent in step (16) is a methanol / acetic acid mixed solution (9:1, V / V), and the elution time is 3 min.

[0025] As a preferred technical solution of this application, the concentration of dioctyl phthalate identified in step (17) is 10. - 9 M, recognition time 15 mi.

[0026] The present invention also includes the dioctyl phthalate molecularly imprinted photoelectrochemical sensor obtained by the above preparation method.

[0027] The present invention also includes the application of the above-mentioned dioctyl phthalate molecularly imprinted photoelectrochemical sensor in the field of detection.

[0028] The present invention also includes the analytical method for the above-mentioned dioctyl phthalate molecularly imprinted photoelectrochemical sensor, characterized by comprising the following steps: 1) Add a 0.1 M phosphate buffer solution (PBS, pH 7.0) to the electrolytic cell. 2) The three-electrode system consisting of the MIP / Cu-T@C3N4 / ITO electrode, the saturated calomel electrode, and the platinum electrode as described in claim 1 was placed in the above-mentioned electrolytic cell. A 500 W high-brightness xenon lamp was used as the light source, and a photoelectric switching test was performed at a bias voltage of -0.1 V. The photocurrent signal generated during the detection process was detected by an electrochemical workstation and displayed on a computer.

[0029] The basic idea of ​​this invention is as follows: A Cu-T@C3N4 composite material is synthesized via ultrasonic treatment, and this composite material is modified onto the surface of an ITO electrode. Dioctyl phthalate and o-phenylenediamine are then modified onto the electrode via electropolymerization. The sensor is obtained by elution with a methanol-acetic acid mixture. The photocurrent (it) test is performed to detect dioctyl phthalate in 0.1 M PBS solution (pH 7.0). The electrode is eluted in a methanol / acetic acid mixture (9:1, V / V) for 33 min, followed by identification in an identification solution containing a certain concentration of dioctyl phthalate for 15 min. The working electrode is placed in the substrate, and the photocurrent (it) test is performed under a 500 W high-brightness xenon lamp with a bias voltage of -0.1 V. Before the next it scan, the electrode is eluted to ensure the working electrode surface is clean. The Cu-T@C3N4 heterojunction material effectively narrows the band gap of TiO2 and introduces oxygen vacancies through Cu²⁺ doping. The layered porous structure of g-C3N4 provides a dispersion carrier for TiO2 nanoparticles and forms a three-dimensional conductive network. The synergistic effect of these two factors significantly improves the absorption efficiency and photogenerated carrier separation capability of the composite material in the visible light region. Combined with molecular imprinting technology, the obtained molecularly imprinted polymer exhibits excellent selective recognition and sensing performance for dioctyl phthalate molecules. This demonstrates that the MIP / Cu-T@C3N4 / ITO electrode possesses good photoelectrochemical analytical capabilities for detecting dioctyl phthalate.

[0030] The advantages of this invention compared to the prior art are as follows: 1. This invention successfully uses Cu-T@C3N4 heterojunction nanomaterials as photosensitive materials. Cu²⁺ doping effectively reduces the band gap of TiO2 and introduces oxygen vacancies, while the layered porous structure of g-C3N4 provides a three-dimensional conductive network for carrier transport. The synergistic effect of the two significantly improves the absorption efficiency and photogenerated carrier separation capability of the material in the visible light region, thereby effectively improving the photoelectric conversion efficiency.

[0031] 2. The Cu-T@C3N4 heterojunction constructs an efficient charge separation channel through band engineering. The tight interfacial contact between Cu-T and g-C3N4 greatly promotes the migration of photogenerated electrons from the inside of the catalyst to the electrode surface, effectively suppressing the recombination of electron-hole pairs, thereby improving the electron migration rate and photoelectric response intensity.

[0032] 3. This invention combines molecular imprinting technology, where o-phenylenediamine and dioctyl phthalate templates are assembled on a modified ITO surface through hydrogen bonding. Compared with other detection technologies, the photoelectrochemical sensor combined with molecular imprinting technology offers repeatability, superior recognition capabilities, greater convenience, and higher sensitivity.

[0033] 4. A molecularly imprinted photoelectrochemical sensor based on a MIP / Cu-T@C3N4 / ITO electrode was established. Its signal amplification and detection performance were significantly improved. This demonstrates that this sensor is a reliable option for environmental pollutant detection and further showcases the broad application prospects of using molecularly imprinted photoelectrochemical sensor technology to replace traditional detection methods in the rapid detection of complex matrices. Attached image description: Figure 1 This is a schematic diagram illustrating the construction of the dioctyl phthalate molecularly imprinted photoelectrochemical sensor of the present invention.

[0034] Figure 2 This is a graph showing the optimized ratio of template molecule to functional monomer for fabricating the dioctyl phthalate molecularly imprinted photoelectrochemical sensor in Example 1 of the present invention.

[0035] Figure 3 This is a curve showing the optimization of the number of electropolymerization cycles for fabricating the dioctyl phthalate molecularly imprinted photoelectrochemical sensor in Example 2 of the present invention.

[0036] Figure 4 This is a curve showing the optimized elution time for the fabrication conditions of the dioctyl phthalate molecularly imprinted photoelectrochemical sensor in Example 3 of the present invention.

[0037] Figure 5 The curve showing the optimization of the modulation and recognition time for the dioctyl phthalate molecularly imprinted photoelectrochemical sensor in Example 4 of this invention.

[0038] Figure 6 This is the operating curve of the dioctyl phthalate molecularly imprinted photoelectrochemical sensor in Example 5 of the present invention. Detailed implementation method: Example 1:

[0039] 1. Fabrication of a dioctyl phthalate molecularly imprinted photoelectrochemical sensor: (1) Add 30 mL of glacial acetic acid (CH3COOH), then dissolve 1.3 g of copper chloride. Stir continuously for 1 h; (2) Add 17 mL of tetrabutyl titanate to the solution in step (1) and stir for 1 h until the substance reacts completely. This solution is called solution A. (3) Place the solution from step (2) in a high-pressure reactor and react for 18 h at a reaction temperature of 200 °C; (4) Wash the solid product obtained in step (3) twice with anhydrous ethanol and distilled water, respectively; (5) The solid product from step (4) was transferred to an evaporating dish and dried in an oven at 80 °C for 12 h. Then it was calcined at 500 °C (muffle furnace) for 2 h to obtain the new material Cu-T; (6) Add 30 mL of deionized water and 0.2 g of hexadecyltrimethylammonium bromide to a beaker and stir in a 40 °C water bath; (7) Add 1.0 g of Cu-T powder obtained in step (5) to the solution in step (6) and stir continuously to obtain solution B; (8) Add 1.74 g of carbon nitride and 20 mL of deionized water to a beaker, and sonicate for 1 h to obtain solution C; (9) Slowly add the B solution obtained in step (8) to the C solution in step (8) and sonicate for 1 h; (10) Centrifuge the solid mixture after the reaction in step (9); (11) The product after centrifugation in step (10) was washed twice with anhydrous ethanol and distilled water, placed in an evaporating dish, and vacuum dried at 80 °C for 12 h to obtain Cu-T@C3N4 hybrid material. (12) Take 4.0 mg of Cu-T@C3N4 hybrid material from step (11) and disperse it in 1 mL of DMF and sonicate it to obtain a uniformly dispersed suspension. (13) ITO conductive glass was ultrasonicated with 15 mL of toluene, acetone, ethanol and ultrapure water for 15 min respectively, and then placed in a 60 ℃ oven to dry for modification. (14) The 10 μL Cu-T@C3N4 suspension from step (12) was modified onto the surface of the ITO electrode and then dried by infrared drying. (15) Electropolymerization is performed on the electrode surface obtained in step (14). The electropolymerization method is cyclic voltammetry. The electropolymerization solution is an acetate-sodium acetate buffer solution (pH=4.2) containing 1 mM dioctyl phthalate and 6 mM o-phenylenediamine. (16) The electrode obtained in step (15) was eluted with a methanol / acetic acid mixed solution (9:1, v / v) to obtain a dioctyl phthalate molecularly imprinted photoelectrochemical sensor. (17) The electrode obtained in step (16) is placed at 10 -9 Identification in M ​​in dioctyl phthalate solution for 15 min.

[0040] Figure 2This figure illustrates the effect of the concentration ratio of dioctyl phthalate template molecules to o-phenylenediamine functional monomers in the electropolymerized molecularly imprinted polymer (MIP) film on the sensor's response current. As shown in the figure, the current change ΔI is largest when the molar ratio of dioctyl phthalate template molecules to o-phenylenediamine is 1:6. ΔI increases as the ratio changes from 1:2 to 1:6; however, when the ratio increases to 1:7 and further to 1:9, ΔI decreases. The ratio of template molecules to functional monomers directly determines the number and quality of imprinted cavities in the MIP film: insufficient functional monomers result in too few specific binding sites; while excessive functional monomers cause the MIP film to become excessively thick, burying many binding sites deep within the polymer matrix and preventing effective binding with the template molecules, while also hindering electron transport. Therefore, this study selected an optimal molar ratio of dioctyl phthalate template molecules to o-phenylenediamine functional monomers of 1:6 for all subsequent photoelectrochemical experiments.

[0041] Example 2: The MIP / Cu-T@C3N4 / ITO electrode obtained in Example 1, which has the optimal concentration ratio of electropolymerized dioctyl phthalate template molecule to o-phenylenediamine functional monomer of 1:6, was used for detection. The analytical methods included: A three-electrode system was constructed using a MIP / Cu-T@C3N4 / ITO electrode, a saturated calomel electrode, and a platinum electrode. The electropolymerization of dioctyl phthalate template molecules to o-phenylenediamine functional monomers was performed at a concentration ratio of 1:6, with electropolymerization cycles of 15, 20, 25, 30, 35, and 40 cycles. 0.1 M PBS buffer solution (pH 7.0) was added to the electrolytic cell, and the system was optimized using IT testing.

[0042] Figure 3 The graphs show the photocurrent (it) values ​​for 15, 20, 25, 30, 35, and 40 electropolymerization cycles in Example 2. The graphs show that the photocurrent is highest at 35 cycles; therefore, 35 cycles were chosen as the optimal number of cycles for the subsequent photoelectrochemical experiments.

[0043] Example 3: The MIP / Cu-T@C3N4 / ITO electrode obtained in Example 1, which has the optimal concentration ratio of electropolymerized dioctyl phthalate template molecule to o-phenylenediamine functional monomer of 1:6, was used for detection. The analytical methods included: A three-electrode system was constructed using a MIP / Cu-T@C3N4 / ITO electrode, a saturated calomel electrode, and a platinum electrode. The electropolymerization of dioctyl phthalate template molecules to o-phenylenediamine functional monomers was performed at a concentration ratio of 1:6, with 35 electropolymerization cycles. Electrode elution times were 1 min, 2 min, 3 min, 4 min, 5 min, and 6 min. 0.1 M PBS buffer solution (pH 7.0) was added to the electrolytic cell, and optimization was performed using the iterative electrochemical method (IT).

[0044] Figure 6 The figure shows the effect of elution time on the photocurrent response of dioctyl phthalate in Example 5. As can be seen from the figure, the photocurrent response of dioctyl phthalate is the largest when the elution time is 3 min, indicating that 3 min is the optimal elution time. Extending the elution time cannot guarantee the elution of dioctyl phthalate from the MIP membrane. Therefore, an elution time of 3 min was selected as the optimal elution time for the subsequent photoelectrochemical experiments.

[0045] Example 4: A three-electrode system was constructed using a MIP / Cu-T@C3N4 / ITO electrode, a saturated calomel electrode, and a platinum electrode. The electropolymerization of dioctyl phthalate template molecules to o-phenylenediamine functional monomers was performed at a concentration ratio of 1:6, with 35 electropolymerization cycles and an electrode elution time of 3 min. Electrode recognition times were observed at 3 min, 5 min, 7 min, 9 min, 11 min, 13 min, 15 min, 17 min, and 20 min. 0.1 M PBS buffer (pH 7.0) was added to the electrolytic cell, and optimization was performed using the iterative method (itM).

[0046] Figure 5 This figure illustrates the effect of recognition time on the photocurrent response of dioctyl phthalate (DIP) in Example 4. The binding of the MIP film to DIP molecules depends on the formation of hydrogen bonds, which requires a certain amount of time to complete. As shown in the figure, the peak current response increases with increasing recognition time, reaching its maximum at 15 min, indicating that the "cavities" in the MIPs have been fully filled. Therefore, a recognition time of 15 min was chosen as the optimal recognition time for subsequent photoelectrochemical experiments.

[0047] Example 5: To examine the practical application performance of this method, the content of dioctyl phthalate in water samples purchased from a local supermarket was tested, and the results are shown in Table 1. Furthermore, as... Figure 6 As shown in (A), the constructed molecularly imprinted photoelectrochemical sensor performs photoelectrochemical testing (it) on dioctyl phthalate under optimal conditions. Simultaneously, as shown in [the diagram]... Figure 6(B) Obtaining the standard curve. When the concentration of dioctyl phthalate is 1×10⁻⁶... -14 - 1×10 -9 Within the range M, the photocurrent intensity and the logarithm of the dioctyl phthalate concentration exhibit a good linear relationship, with the linear equation being: I(µA) = 0.00592 Log C(M) + 0.11179 (R 2 =0.994) (S / N=3), the detection limit is 1.914×10 -13 M.

[0048] Table 1. Detection of dioctyl phthalate residues in actual samples by the constructed sensor (n=3) Sample number Added concentration (M) Detected concentration (M) Recovery rate (%) RSD (%) 1 0 - - - 2 <![CDATA[5.0×10 -11 ]]> <![CDATA[4.9425×10 -11 ]]> 98.85 % 2.53 % 3 <![CDATA[1.0×10 -10 ]]> <![CDATA[1.003×10 -9 ]]> 100.30 % 1.33 % 4 <![CDATA[5.0×10 -10 ]]> <![CDATA[4.791×10 -9 ]]> 95.82 % 3.12 %

Claims

1. A method for preparing a molecularly imprinted photoelectrochemical sensor for detecting dioctyl phthalate, characterized in that, Includes the following steps: (1) Add glacial acetic acid and copper chloride to a beaker and stir; slowly add tetrabutyl titanate and stir until the reaction is complete to obtain solution A; transfer the obtained solution A to a high-pressure reactor for reaction; after the reactor cools naturally to room temperature, centrifuge the reaction product; centrifuge and dry the product, and then dry it at high temperature to obtain Cu-T material; (2) Add deionized water and hexadecyltrimethylammonium bromide to a beaker and stir in a water bath; add Cu-T powder obtained in step (1) and stir continuously to obtain solution B; add carbon nitride and deionized water to a beaker and sonicate to obtain solution C. (3) The solution B obtained in step (2) was slowly added dropwise to solution C and ultrasonically treated; the solid mixture after the reaction was separated by centrifugation; the washed product was placed in an evaporating dish and vacuum dried to obtain Cu-T@C3N4 hybrid material; (4) Take the composite material obtained in step (3) and disperse it in DMF and sonicate it to obtain a uniformly dispersed suspension; (5) The Cu-T@C3N4 suspension obtained in step (4) is modified onto a clean ITO electrode surface and dried by infrared; then the electrode is placed in a mixed solution containing o-phenylenediamine and dioctyl phthalate for electropolymerization. (6) The electrode obtained in step (5) was eluted with a methanol / acetic acid mixture and then placed in a dioctyl phthalate solution for identification, thus obtaining a methyl parathion molecularly imprinted photoelectrochemical sensor.

2. The method for preparing a dioctyl phthalate molecularly imprinted photoelectrochemical sensor according to claim 1, characterized in that, In step (1), the amount of glacial acetic acid used was 30 mL, the amount of copper chloride was 1.3 g, and the stirring time was 1 h; the amount of tetrabutyl titanate used was 17 mL, and the stirring time was 1 h; the reaction temperature in the high-pressure reactor was 200 ℃, and the reaction time was 18 h; the product was washed with anhydrous ethanol and ultrapure water respectively, and then subjected to a reaction at 8000 rpm·min. -1 Centrifuge for 5 min each time, and repeat twice. The precipitate is dried at 80 ℃ for 12 h, or dried in a muffle furnace at 500 ℃ for 2 h.

3. The method for preparing a dioctyl phthalate molecularly imprinted photoelectrochemical sensor according to claim 1, characterized in that, In step (2), the amount of hexadecyltrimethylammonium bromide used is 0.2 g, the amount of deionized water added is 30 mL, the water bath temperature is 40 ℃, the amount of Cu-T used is 1.0 g, the amount of carbon nitride used is 1.74 g, the amount of deionized water added is 20 mL, and the ultrasonic time is 1 h.

4. The method for preparing a dioctyl phthalate molecularly imprinted photoelectrochemical sensor according to claim 1, characterized in that, The ultrasound time in step (3) is 1 hour; at 8000 rpm·min -1 Centrifuge for 5 min, then wash with anhydrous ethanol and ultrapure water respectively, and centrifuge at 8000 rpm·min. -1 Centrifuge for 5 min, then centrifuge twice; dry the precipitate at 80 ℃ for 12 h.

5. The method for preparing a dioctyl phthalate molecularly imprinted photoelectrochemical sensor according to claim 1, characterized in that, In step (4), 4.0 mg of Cu-T@C3N4 composite material was added to 1 mL of DMF.

6. The method for preparing a dioctyl phthalate molecularly imprinted photoelectrochemical sensor according to claim 1, characterized in that, In step (5), 10 μL of Cu-T@C3N4 dispersion was modified on a clean ITO electrode surface and dried by infrared spectroscopy; the electropolymerization solution was an acetate-sodium acetate buffer solution (pH=4.2) containing 1 mM dioctyl phthalate and 6 mM o-phenylenediamine.

7. The method for preparing a dioctyl phthalate molecularly imprinted photoelectrochemical sensor according to claim 1, characterized in that, In step (6), the electrode eluent is a methanol / acetic acid mixture (9:1, V / V), and the elution time is 3 min; the concentration of dioctyl phthalate identified is 10. -9 M, recognition time 15 min.

8. The dioctyl phthalate molecularly imprinted photoelectrochemical sensor obtained by the preparation method according to any one of claims 1 to 7.

9. The application of the dioctyl phthalate molecularly imprinted photoelectrochemical sensor according to claim 8 in the field of detection.

10. The application of the dioctyl phthalate molecularly imprinted photoelectrochemical sensor according to claim 9 in the field of detection, characterized in that, Includes the following steps: 1) Add a buffer solution containing 0.1 M PBS (pH 7.0) to the electrolytic cell; 2) A three-electrode system consisting of the composite material-modified ITO electrode, the saturated calomel electrode, and the platinum electrode as described in claim 1 was placed in the above-mentioned electrolytic cell. A 500 W high-brightness xenon lamp was used as the light source, and a photoelectric switching test was performed at a bias voltage of -0.1 V. The photocurrent signal generated during the test was detected by an electrochemical workstation and displayed on a computer.

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