Photoelectrochemical self-energized sensor and preparation method and application thereof

Abstract

The invention belongs to the technical field of photoelectrochemical detection, and particularly relates to a photoelectrochemical self-energized sensor as well as a preparation method and application thereof. According to the photoelectrochemical self-powered sensor, an electrode jointly modified by an aptamer and a 3D CdS-dWO3.H2O nano material is used as a photo-anode electrode, the photo-anode electrode, a cathode platinum sheet and a single-chamber quartz electrolytic tank are assembled together to form the photoelectrochemical self-powered sensor, and when the photoelectrochemical self-powered sensor is used for isocarbophos detection, the photoelectrochemical self-powered sensor shows high stability, high sensitivity and a wide linear range; and the method has good reproducibility, and can realize simple, rapid, efficient and specific detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of photoelectrochemical detection, and in particular relates to a photoelectrochemical self-powered sensor and a preparation method and application thereof. Background Art

[0002] Isocarbophos is one of the most important organophosphorus pesticides. It is widely used to kill various leaf-eating insects and soil insects on plants such as wheat and cotton, resulting in its widespread residue in the ecological environment, causing esophageal, skin and respiratory poisoning, acute toxicity and carcinogenicity. Considering the high toxicity and carcinogenicity of isocarbophos, it is of great significance to establish a simple, sensitive, rapid and economical detection method for isocarbophos, which is of great significance to environmental protection and human health.

[0003] The mainstream analytical methods for isocarbophos residues are based on chromatography, including high performance liquid chromatography, gas chromatography-mass spectrometry and high performance liquid chromatography-mass spectrometry. These instrumental analysis methods have the obvious advantages of high sensitivity and accuracy, but they also have the disadvantages of expensive instruments, time-consuming sample pretreatment and unprofessional testing personnel, which limit their application in on-site testing or rapid screening. Fluorescence, chemiluminescence and colorimetry can also be used for isocarbophos analysis. These methods are simple to operate but not sensitive. In view of this, it is urgent to establish a low-cost, simple and fast, highly sensitive and reproducible method to overcome the above shortcomings.

[0004] Self-powered photoelectrochemical (PEC) sensors have attracted widespread attention due to their simple construction, small size, fast response speed and low cost. Usually, self-powered sensors are composed of a photoanode and a cathode. Under light conditions, the semiconductor material of the photoanode generates electrons and holes, and the electrons can be transferred to the cathode through an external circuit, where a reduction reaction occurs. At present, PEC sensors are rarely used in the detection of isothiocarb. Summary of the invention

[0005] The purpose of the present invention is to provide a photoelectrochemical self-powered sensor and a preparation method and application thereof. Specifically, an electrode modified with an aptamer and a 3D CdS-dWO3·H2O nanomaterial is used as a photoanode electrode, and Pt is used as a cathode to construct a self-powered sensor, and the sensor is applied to detect isothiocarbamide in the environment. Compared with the 3D CdS monomer, the introduction of dWO3·H2O to construct a heterojunction can accelerate the charge transfer, thereby effectively promoting the separation of electrons and holes and enhancing the photoelectric conversion efficiency.

[0006] The method for preparing the photoelectrochemical self-powered sensor comprises the following steps:

[0007] (1) The FTO electrode was ultrasonically cleaned in acetone, ethanol and deionized water for 30 min respectively. First, 3D CdS powder was added to the dWO3·H2O dispersion and mixed, then the mixed dispersion was coated on the FTO surface, dried, and then chitosan solution was added dropwise and dried, which was represented as 3D CdS-dWO3·H2O / FTO photoanode; wherein the mass ratio of the 3D CdS powder to dWO3·H2O was 2-3:2-18; preferably, the mass ratio was 1:1-4.

[0008] Furthermore, the concentration of the dWO3·H2O dispersion is 2 to 18 mg / mL.

[0009] Furthermore, the preparation method of the 3D CdS powder is: dissolving CdCl2·2.5H2O in an ethanol aqueous solution, then adding PMMA colloidal crystal balls, soaking at room temperature for 6 hours, and drying; adding to a Na2S·9H2O aqueous solution, soaking at 60°C for 3 hours, washing, and drying; heating in a 400°C muffle furnace for 3 hours to obtain 3D CdS powder; wherein the mass ratio of the CdCl2·2.5H2O and PMMA colloidal crystal balls is 1.2457:1.5.

[0010] Furthermore, the preparation method of dWO3·H2O is: dissolving Na2WO4·2H2O, citric acid monohydrate and glucose in ultrapure water, stirring until transparent; adding HCl, stirring continuously for 30 minutes, hydrothermally reacting at 120°C for 24 hours, naturally cooling, collecting precipitates by centrifugation, washing, and drying to obtain dWO3·H2O powder; wherein the molar ratio of Na2WO4·2H2O, citric acid monohydrate and glucose is 1:1.5:1.

[0011] (2) Add aptamer 1 solution to the prepared 3D CdS-dWO3·H2O / FTO photoanode surface, and incubate the sensor at room temperature overnight to obtain the photoanode electrode (apt / 3D CdS-dWO3·H2O / FTO). Then, a Pt cathode, a single-chamber quartz electrolytic cell, and a photoanode electrode apt / 3D CdS-dWO3·H2O / FTO were assembled together to construct a self-powered sensor;

[0012] The concentration of the aptamer 1 solution was 3 μmol / L.

[0013] Furthermore, the nucleotide sequence of the aptamer 1 is as follows:

[0014] The base sequence of aptamer 1 is CgC TgCAAg CTT TTT TgACTgACT gCAgCg.

[0015] Furthermore, the volume ratio of the 3D CdS / dWO3·H2O mixed solution, the chitosan solution, and the aptamer 1 solution is 1:1:1.

[0016] The present invention also provides an application of the self-powered sensor in the photoelectrochemical detection of isothiocarb. The photoanode apt / 3D CdS-dWO3·H2O / FTO is incubated in isothiocarb solutions of different concentrations at room temperature for 40 minutes, and then the electrode is rinsed with ultrapure water and then used to detect isothiocarb.

[0017] The specific detection method includes the following steps:

[0018] S1. Prepare Na2SO4 solution;

[0019] S2, preparing isocarbophos with different concentrations;

[0020] Accurately weigh a certain amount of isocarbothion and dilute it step by step with 3 μmol / L aptamer 2 solution to obtain a series of isocarbothion standard solutions with different concentrations, with a concentration range of 1.0×10 -11 g / mL~1.0×10 -6 g / mL;

[0021] The nucleotide sequence of the aptamer 2 is as follows:

[0022] The base sequence of aptamer 2 is ATT CTT gAT CgC CAC ggT CTg gAAAAAgAg.

[0023] S3. Drawing of standard curve:

[0024] A series of known concentrations of isothiocarb standard solutions were selected and dropped onto the prepared electrode apt / 3DCdS-dWO3·H2O / FTO, and dried naturally at room temperature. The obtained modified electrode was marked as ICP / apt / 3DCdS-dWO3·H2O / FTO.

[0025] ICP / apt / 3D CdS-dWO3·H2O / FTO was used as the photoanode for photoelectrochemical testing, Pt was used as the cathode, and a photoelectrochemical self-powered system was formed. Na2SO4 solution was used as the electrolyte, the xenon lamp light source current was kept at 20A, and the horizontal distance between the light source outlet and the FTO conductive surface was kept at 15cm. The photocurrent of the circuit was tested with a two-electrode system, and a series of corresponding relationships between the concentration of isocarbothion and the short-circuit current were obtained, so as to calculate the standard curve of isocarbothion, establish a linear relationship between the short-circuit current value after adding isocarbothion and the logarithm of the concentration of isocarbothion, and obtain the corresponding linear regression equation;

[0026] S4. Actual sample testing:

[0027] The aptamer 2 is added to the test solution containing aqueous phosphamidon, and then dripped on the photoanode electrode and dried to obtain ICP / apt / 3D CdS-dWO3·H2O / FTO; ICP / apt / 3D CdS-dWO3·H2O / FTO is used as the photoanode of the photoelectrochemical test, Pt is used as the cathode, and a photoelectrochemical self-powered system is composed. Na2SO4 solution is used as the electrolyte, a xenon lamp is used as the light source, and the short-circuit current of the circuit is tested with a two-electrode system; the short-circuit current value is substituted into the linear regression equation in step S3 for calculation to obtain the concentration of ICP in the test solution.

[0028] Preferably, in steps S3 and S4, the concentration of the Na2SO4 solution is 0.1M.

[0029] The minimum detection limit of the concentration of isocarbothion solution detected by the sensor is 0.396×10 -12 g / mL.

[0030] The beneficial effects of the present invention are as follows: compared with traditional sensors, the present invention has the following advantages:

[0031] (1) The present invention forms a heterojunction by combining 3D CdS and dWO3·H2O, which can accelerate charge transfer, thereby effectively promoting the separation of electrons and holes and enhancing the photoelectric conversion efficiency. At the same time, the introduction of the aptamer enables the sensor to have a specific detection effect on isothiocarb.

[0032] (2) The self-powered sensor prepared by the present invention exhibits high stability, high sensitivity, wide linear range, and good reproducibility when used for the detection of isothiocarb, and can achieve simple, rapid, efficient and specific detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will be further described below with reference to the accompanying drawings and examples.

[0034] Figure 1 It is a flow chart of the preparation of the sensor and the detection of isocarbophos in the invention;

[0035] Figure 2 is the photocurrent of 3D CdS-dWO3·H2O / FTO photoanode with different ratios (3D CdS:dWO3·H2O) in the sensor;

[0036] Figure 3 is a scanning electron microscope image of the 3D CdS-dWO3·H2O / FTO photoanode in the sensor;

[0037] Figure 4The photocurrent curves of different photoanodes used in the sensor: dWO3·H2O / FTO (a), 3D CdS / FTO (b) and 3D CdS-dWO3·H2O / FTO (c);

[0038] Figure 5 are the current-time curves during the sensor construction process: 3D CdS-dWO3·H2O / FTO (a), apt / 3D CdS-dWO3·H2O / FTO (b), and ICP / apt / 3D CdS-dWO3·H2O / FTO (c);

[0039] Figure 6 is the photocurrent curve of the sensor for different concentrations of ICP;

[0040] Figure 7 This is the standard curve of the photocurrent size of the sensor for different ICP concentrations and the logarithm of the ICP concentration. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below with reference to the embodiments.

[0042] like Figure 1 As shown, a preparation method of a photoelectrochemical self-powered sensor and its application in the detection of isothiocarb, using 3D CdS-dWO3·H2O / FTO as a photoanode and Pt as a cathode to form a self-powered system, which realizes the specific detection of isothiocarb.

[0043] The following aptamer sequences are shown below:

[0044] The base sequence of aptamer 1 is CgC TgCAAg CTT TTT TgACTgACT gCAgCg;

[0045] The base sequence of aptamer 2 is ATT CTT gAT CgC CAC ggT CTg gAAAAAgAg;

[0046] Purchased from Sangon Biotech (Shanghai) Co., Ltd.

[0047] Example 1

[0048] A method for preparing a photoelectrochemical self-powered sensor comprises the following steps:

[0049] (1) Preparation of 3D CdS materials

[0050] Monodisperse polymethyl methacrylate (PMMA) colloidal crystal spheres were prepared by soap-free emulsion polymerization. 5wt% NaOH solution and raw material MMA were mixed in a separatory funnel at a volume ratio of 3:1. After tightening the bottle cap, shake vigorously for about 1min, then let it stand and wait for the solution to separate. The upper layer is MMA monomer. If the upper clear liquid is turbid, repeat the above experiment until it is clear. Deionized water and MMA are deoxygenated by nitrogen for 10min. 18mL MMA and 180mL deionized water are measured and added to a three-necked flask. The oil bath is heated to 75℃, the speed is 200r / min, and stirred for 1h. 0.15g potassium persulfate (KPS) is quickly added and the reaction ends after 5h. PMMA colloidal crystal spheres are separated from the prepared colloidal suspension by centrifugation at a speed of 1200r / min for 10min. The precipitate is washed three times with deionized water. The precipitate was dispersed into deionized water by ultrasonic treatment, and the colloidal suspension was poured into a small beaker and then evaporated in a water bath at 80 °C. The obtained PMMA colloidal crystals were stored in a sealed glass container.

[0051] Dissolve 1.2457g of CdCl2·2.5H2O in 10mL of ethanol-water solution (Vethanol:Vwater=1:1). Soak 1.5g of PMMA colloidal crystal spheres in the above solution at room temperature for 6h, and then dry at 60℃ for 2h. Add the above sample to 10mL of 0.5mol / LNa2S·9H2O aqueous solution and soak at 60℃ for 3h. Wash with deionized water 3 times to remove excess sodium sulfide, and then dry at 60℃ for 3h. Heat the sample in a muffle furnace at 400℃ for 3h to obtain 3D CdS powder.

[0052] (2) Preparation of dWO3·H2O materials

[0053] First, 0.5 mM Na2WO4·2H2O, 0.75 mM citric acid monohydrate (CA), and 0.5 mM glucose were dissolved in 15 mL of ultrapure water. The mixture solution was then stirred at room temperature until it became transparent. After that, 1.5 mL of 6 M HCl was added to the mixture solution, which was then stirred for 30 minutes. Finally, the mixture solution was transferred to a hydrothermal reactor at 120 ° C for 24 hours. After natural cooling, the precipitate was collected by centrifugation and washed three times with deionized water, and vacuum dried at 60 ° C for 12 hours to obtain dWO3·H2O powder.

[0054] (3) Preparation of photoanode (3D CdS-dWO3·H2O / FTO)

[0055] 2 mg, 3 mg, 8 mg and 18 mg of dWO3·H2O were dispersed in 1 mL of DMF solution to obtain dWO3·H2O dispersions with concentrations of 2 mg / mL, 3 mg / mL, 8 mg / mL and 18 mg / mL.

[0056] FTO electrode (area 1×2cm 2 ) were ultrasonically cleaned in acetone, ethanol and deionized water for 30 min respectively.

[0057] First, 3 mg of 3D CdS powder was dispersed in 1 mL of 2 mg / mL dWO3·H2O dispersion, 20 μL of the mixed dispersion was dropped on the FTO surface and dried, and then 20 μL of 0.1% chitosan solution was dropped and dried, which was expressed as 3D CdS:dWO3·H2O=1.5:1.

[0058] 2 mg of 3D CdS powder was dispersed in 1 mL of 2 mg / mL dWO3·H2O dispersion, 20 μL of the mixed dispersion was dropped on the FTO surface and dried, and then 20 μL of 0.1% chitosan solution was dropped and dried, which was expressed as 3D CdS:dWO3·H2O=1:1.

[0059] 2 mg of 3D CdS powder was dispersed in 1 mL of 3 mg / mL dWO3·H2O dispersion, 20 μL of the mixed dispersion was dropped on the FTO surface and dried, and then 20 μL of 0.1% chitosan solution was dropped and dried, which was expressed as 3D CdS:dWO3·H2O=1:1.5.

[0060] The preparation of 3D CdS:dWO3·H2O=1:4 and dWO3·H2O:3D CdS=1:9 is similar.

[0061] 3D CdS-dWO3·H2O / FTO was used as the photoanode for the photoelectrochemical test, Pt was used as the cathode, and a photoelectrochemical self-powered system was formed. 0.1MNa2SO4 solution was used as the electrolyte, the xenon lamp light source current was maintained at 20A, and the horizontal distance between the light source outlet and the FTO conductive surface was maintained at 15cm. The photocurrent of the circuit was tested with a two-electrode system. The test results are shown in Figure 2 shown.

[0062] from Figure 2 It can be seen that when 3D CdS:dWO3·H2O=1:4, the photocurrent value is the largest. Therefore, the composite ratio of dWO3·H2O / 3D CdS / FTO of 1:4 was selected for subsequent experiments.

[0063] The SEM image of dWO3·H2O / 3D CdS / FTO photoanode is shown in Figure 3 .

[0064] (4) Preparation of self-powered aptamer sensor

[0065] The prepared 3D CdS-dWO3·H2O / FTO photoanode was dripped with 20 μL of 3 μM aptamer 1 solution, and the sensor was incubated overnight at room temperature to obtain the photoanode apt / 3D CdS-dWO3·H2O / FTO. Then the Pt cathode, single-chamber quartz electrolytic cell and photoanode apt / 3D CdS-dWO3·H2O / FTO were assembled together to construct a self-powered sensor.

[0066] Example 2

[0067] Sensors prepared from dWO3·H2O, 3D CdS, and 3D CdS-dWO3·H2O, denoted as dWO3·H2O / FTO, 3D CdS / FTO, and 3D CdS-dWO3·H2O / FTO. Photocurrent curves as photoanode.

[0068] The preparation steps of dWO3·H2O / FTO are as follows: disperse the dWO3·H2O prepared in Example 1 in DMF solvent at a concentration of 2 mg / ml, drop 20 μL of the dispersion on the FTO surface, and dry it;

[0069] The preparation steps of 3D CdS / FTO are as follows: disperse the 3D CdS prepared in Example 1 in DMF solvent at a concentration of 2 mg / ml, drop 20 μL of the dispersion on the FTO surface, dry it, then drop 20 μL of 0.1% chitosan solution, and dry it;

[0070] The FTO electrode (area 1×2 cm 2 ) were ultrasonically cleaned in acetone, ethanol and deionized water for 30 min respectively.

[0071] The preparation steps of 3D CdS-dWO3·H2O / FTO are the same as those in Example 1.

[0072] The photocurrent curves of dWO3·H2O, 3D CdS and 3D CdS-dWO3·H2O as photoanodes were compared.

[0073] dWO3·H2O / FTO(a), 3D CdS / FTO(b), 3D CdS-dWO3·H2O / FTO(c) were used as photoanodes for photoelectrochemical tests, Pt was used as cathode, and a photoelectrochemical self-powered system was formed. A 0.1M Na2SO4 solution was used as the electrolyte. The xenon lamp light source current was kept at 20A, and the horizontal distance between the light source outlet and the FTO conductive surface was kept at 15cm. The photocurrent of the circuit was tested with a two-electrode system. Figure 4 are the current-time curves of different photoanodes used in the sensor.

[0074] Example 3

[0075] Comparison of the self-powered system prepared by photoanode and Pt cathode before and after the combination of ICP and APT.

[0076] 3D CdS-dWO3·H2O / FTO (a), apt / 3D CdS-dWO3·H2O / FTO (b) and ICP / apt / 3D CdS-dWO3·H2O / FTO (c) prepared in Example 1 were used as photoanodes for photoelectrochemical tests, Pt was used as cathode, and a photoelectrochemical self-powered system was formed. A Na2SO4 solution with a concentration of 0.1 M was used as the electrolyte. The xenon lamp light source current was maintained at 20 A, and the horizontal distance between the light source outlet and the FTO conductive surface was maintained at 15 cm. The photocurrent of the circuit was tested using a two-electrode system. Figure 5 are the current-time curves of different photoanodes used in the sensor.

[0077] The preparation steps of ICP / apt / 3D CdS-dWO3·H2O / FTO are as follows: Prepare the standard solution of isothiocarb: weigh a certain amount of isothiocarb and dissolve it in the 3 μM aptamer 2 solution, dilute it, and obtain the concentration of isothiocarb to be 1.0×10 -6 20 μL of the standard solution of carbofuran was drop-coated on the apt / 3D CdS-dWO3·H2O / FTO prepared in Example 1 and dried naturally at room temperature for 40 minutes.

[0078] Example 4

[0079] The application of a photoelectrochemical self-powered sensor in the photoelectrochemical detection of isothiocarb has the following steps:

[0080] (1) According to the method of Example 1, apt / 3D CdS-dWO3·H2O=1:4 was selected to prepare the photoanode. Then, a Pt cathode, a single-chamber quartz electrolytic cell and the photoanode apt / 3D CdS-dWO3·H2O / FTO were assembled together to construct a self-powered sensor.

[0081] (2) Drawing of standard curve:

[0082] Prepare the standard solution of isothiocarb: dissolve a certain amount of isothiocarb in 3 μmol / L aptamer 2 solution and dilute it step by step to obtain the concentrations of isothiocarb of 1.0×10 -11 g / mL, 1.0×10 -10 g / mL, 1.0×10 -9 g / mL, 1.0×10 -8 g / mL, 1.0×10 -7 g / mL, 1.0×10 -6g / mL of isothiocarb standard solution, take 20 μL of isothiocarb standard solution of known concentration and apply it on the prepared electrode apt / 3DCdS-dWO3·H2O / FTO, dry it naturally at room temperature for 40 minutes, and obtain the modified electrode ICP / apt / 3DCdS-dWO3·H2O / FTO.

[0083] ICP / apt / 3D CdS-dWO3·H2O / FTO was used as the photoanode for the photoelectrochemical test, Pt was used as the cathode, and a photoelectrochemical self-powered system was formed. A 0.1M Na2SO4 solution was used as the electrolyte. The xenon lamp light source current was kept at 20A, and the horizontal distance between the light source outlet and the FTO conductive surface was kept at 15cm. The photocurrent of the circuit was tested with a two-electrode system, and a series of photocurrent curves of different ICP concentrations were obtained ( Figure 6 ), and thus the standard curve of isocarbophos was calculated ( Figure 7 ), and then the linear relationship between the logarithmic value of the concentration of isocarbothion and the photocurrent was obtained, the correlation coefficient (R2) was 0.99901, and the linear regression equation was I = 0.02661-0.01157Lg [C ICP The detection range of (g / mL)] is 1.0×10 -11 -1.0×10 -6 g / mL, the minimum detection limit is 0.396×10 -12 g / mL.

[0084] like Figure 6 As shown in the figure, the peak values ​​of the concentration curve of isocarbophos are as follows from a to f: 1.0×10 -11 g / mL, 1.0×10 -10 g / mL, 1.0×10 -9 g / mL, 1.0×10 -8 g / mL, 1.0×10 -7 g / mL, 1.0×10 -6 g / mL.

[0085] (6) Testing of actual samples

[0086] Dissolve phosphamidon in 3 μmol / L aptamer 2 solution, and then take a certain amount of river water and tap water after removing impurities to dilute it to obtain 1 μg / ml phosphamidon solution, drop it on apt / 3D CdS-dWO3·H2O / FTO, dry it naturally at room temperature for 40 minutes to make an electrode for photoelectrochemical detection, and calculate the concentration of phosphamidon in the sample to be tested according to the regression equation corresponding to the above standard curve. The results are listed in Table 1.

[0087] Table 1 Determination results of ICP in water samples

[0088]

[0089] As shown in Table 1, the samples were tested three times in parallel, with a relative standard deviation of less than 5% and a spike recovery range of 98.0% to 105.3%. These results verify that this method can be used for testing in actual samples.

[0090] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A photoelectrochemical self-powered sensor, characterized in that: The electrode modified with aptamer and 3D CdS-dWO3·H2O nanomaterials was used as the photoanode electrode and Pt was used as the cathode to construct a photoelectrochemical self-powered sensor.

2. The photoelectrochemical self-powered sensor according to claim 1, characterized in that: The method for preparing the photoanode electrode comprises the following steps: (1) Add 3D CdS powder to dWO3·H2O dispersion and mix well to obtain 3D CdS-dWO3·H2O mixed solution, apply it on the cleaned FTO surface and dry it; then apply chitosan solution and dry it; (2) coating the aptamer 1 solution, incubating at room temperature, and drying to obtain a photoanode electrode; the base sequence of the aptamer S1 is CgC TgC AAg CTT TTT TgA CTg ACT gCA gCg.

3. The photoelectrochemical self-powered sensor according to claim 2, characterized in that: The mass ratio of the 3D CdS powder to dWO3·H2O is 2-3: 2-18; The concentration of the dWO3·H2O dispersion is 2-18 mg / mL; The volume ratio of the 3D CdS-dWO3·H2O mixed solution, chitosan solution, and aptamer S1 solution is 1:1:1; The concentration of the aptamer S1 solution is 3 μmol / L; The concentration of the chitosan solution is 0.1 wt %.

4. The photoelectrochemical self-powered sensor according to claim 2, characterized in that: The preparation method of the 3D CdS powder comprises the following steps: dissolving CdCl2·2.5H2O in an ethanol aqueous solution, then adding PMMA colloidal crystal balls, soaking at room temperature for 6 hours, and drying; adding to a Na2S·9H2O aqueous solution, soaking at 60°C for 3 hours, washing, and drying; heating in a muffle furnace at 400°C for 3 hours to obtain 3D CdS powder; wherein the mass ratio of the CdCl2·2.5H2O to the PMMA colloidal crystal balls is 1.2457:1.

5.

5. The photoelectrochemical self-powered sensor according to claim 2, characterized in that: The preparation of the dWO3·H2O is as follows: Na2WO4·2H2O, citric acid monohydrate and glucose are dissolved in ultrapure water and stirred until transparent; HCl is added, stirring is continued for 30 minutes, hydrothermally reacted at 120° C. for 24 hours, naturally cooled, centrifuged to collect the precipitate, washed, and dried to obtain dWO3·H2O powder; wherein the molar ratio of Na2WO4·2H2O, citric acid monohydrate and glucose is 1:1.5:

1.

6. Use of the photoelectrochemical self-powered sensor according to any one of claims 1 to 5 in detecting isocarbophos, characterized in that: The specific detection method includes the following steps: The aptamer 2 is added to the test solution containing aqueous phosphamidon, and then drop-coated on the photoanode electrode and dried to obtain ICP / apt / 3D CdS-dWO3·H2O / FTO; ICP / apt / 3D CdS-dWO3·H2O / FTO is used as the photoanode of the photoelectrochemical test, Pt is used as the cathode, and a photoelectrochemical self-powered system is composed. Na2SO4 solution is used as the electrolyte, a xenon lamp is used as the light source, and the short-circuit current of the circuit is tested by a two-electrode system; the short-circuit current value is substituted into the linear regression equation of the standard curve to calculate the concentration of ICP in the test solution; wherein the base sequence of the aptamer S2 is ATT CTT gAT CgC CAC ggT CTg gAA AAA gAg.

7. The use according to claim 6, characterized in that: The concentration of Na2SO4 solution is 0.1M.

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