Preparation method and application of a photo-assisted enhanced self-powered electrochemical sensor

Abstract

The application belongs to the technical field of electrochemical detection and analysis, and particularly relates to a light-assisted enhanced self-powered electrochemical sensor for detecting microcystin-RR (MC-RR) and a preparation method thereof. 18 O 49 A heterojunction is further formed with Nb2C MXene. Polarization of the molecule can be achieved by doping Mo atoms into W 18 O 49 , which promotes electron transfer. The Fermi level of Nb2C MXene is lower, and the conductivity is higher. The application widens the application of W 18 O 49 in self-powered photoelectrochemical sensors, and the prepared sensor has a wide detection range, high sensitivity and low detection limit, and is of great significance for detecting MC-RR.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrochemical detection analysis, and particularly relates to a preparation method of a light-assisted enhanced self-powered electrochemical sensor for detecting microcystin-RR. BACKGROUND

[0002] Eutrophication of water bodies, rising carbon dioxide content in the atmosphere, and climate change are important sources of biologically active blue-green algae toxins. Among them, microcystin (MCs) is a kind of biologically active cyclic heptapeptide compound, which is the most widely distributed hepatotoxin and is mainly produced by freshwater algae Microcystis aeruginosa. Microcystin is a heptapeptide monocyclic hepatotoxin, which has a certain stability due to the presence of a cyclic structure and a spacer double bond in the structure. It can strongly inhibit the activity of protein phosphatase and poses an increasing threat to ecology and human health. At present, the detection and quantitative analysis methods of MCs such as protein phosphatase inhibition assay (PPIA), enzyme-linked immunosorbent assay (ELISA), high-performance liquid chromatography (HPLC), and liquid chromatography-mass spectrometry (LC-MS) have problems such as high cost, complicated operation, or high requirements for instruments. With the promulgation of the Drinking Water Health Standards (GB 5749-2022) of China, the content of microcystin in drinking water is limited to 1 μg / L. The implementation of this standard puts forward higher requirements for water quality, and therefore it is necessary to develop a method for rapid detection of microcystin with high sensitivity.

[0003] Self-powered photoelectrochemical sensors (PEC) have attracted extensive attention due to their simple construction, small size, and low cost. A PEC is usually composed of a photoanode and a cathode. Under light conditions, the photoanode generates electrons (e-) and holes (h+). The electrons can be transferred to the cathode through an external circuit, and a reduction reaction occurs at the cathode. Under light conditions, the electrons generated by the photoanode are driven by the inherent bias voltage difference between the anode and the cathode to flow to the cathode through the external circuit. Therefore, the performance of the self-powered sensor depends largely on the photoelectrochemical performance of the photoanode.

[0004] As a typical n-type semiconductor, W 18 O 49 There are abundant oxygen vacancies on the surface, and there are abundant low-coordination active metal atoms and high surface binding energy. In order to further improve the performance, designing a suitable surface atomic configuration through metal doping may be a favorable strategy.

[0005] In recent years, MXenes have attracted extensive attention due to their excellent metal conductivity, wide light absorption characteristics and high electron transfer efficiency. Coupling semiconductor materials and MXenes to form heterojunctions can effectively accelerate electron transfer, thereby promoting the separation of electrons and holes and increasing the photoelectric conversion efficiency. In order to further improve the electron transfer efficiency, two-dimensional (2D) transition metal carbide MXenes are selected as electron transfer bridges to promote the migration and separation of charges. Among the many MXenes, niobium carbide (Nb2C) MXene has attracted great interest due to its potential applications in batteries, supercapacitors, photocatalysts, fuel cells and photovoltaics. Nb2C MXene has a lower Fermi level, higher conductivity and wettability, which makes Nb2C MXene a good candidate material. SUMMARY

[0006] The purpose of the present application is to provide a preparation method and application of a light-assisted enhanced self-powered electrochemical sensor. The present application develops a new type of heterojunction self-powered photoelectrochemical sensor by assembling platinum sheets and Mo-W 18 O 49 / Nb2C MXene. After coupling with MC-RR aptamer, the target can be specifically captured on the electrode, increasing the steric hindrance, thereby realizing sensitive detection of MC-RR.

[0007] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0008] One of the purposes of the present application is to provide a light-assisted enhanced self-powered electrochemical sensor, which is based on Mo-doped W 18 O 49 nanomaterials and Nb2C MXene nanocomposites (Nb2C / Mo-W 18 O 49 ) as the substrate, and a specific recognition element aptamer is modified on the conductive surface of indium tin oxide conductive glass (ITO).

[0009] The second purpose of the present application is to provide a preparation method of the above-mentioned light-assisted enhanced self-powered electrochemical sensor, and the preparation method steps are as follows:

[0010] (1) Preparation of Mo-W 18 O 49 nanomaterials:

[0011] WCl6 was dissolved in anhydrous ethanol, and then stirred vigorously for 30 min to prepare a transparent light yellow solution, i.e., an ethanol solution of WCl6; and MoCl5 was dissolved in anhydrous ethanol to obtain an ethanol solution of MoCl5. Subsequently, the ethanol solution of MoCl5 was added to the ethanol solution of WCl6, and further stirred to mix uniformly, to obtain a mixed solution, and then the mixed solution was transferred into a high-pressure kettle lined with tetrafluoroethylene, sealed and heated at 150-200°C for 10-12 hours. After the high-pressure kettle was cooled to room temperature, the synthesized product was centrifuged and washed with anhydrous ethanol for several times. Finally, the product was dried in a vacuum oven at 60-80°C for 8-10 hours, to obtain Mo-W 18 O 49 nanomaterials.

[0012] (2) Preparation of photoanode:

[0013] The Mo-W 18 O 49 nanomaterials were dispersed in a DMF (N, N-dimethylformamide) solution, and ultrasonically mixed uniformly, to obtain a Mo-W 18 O 49 dispersion. The Mo-W 18 O 49 dispersion was drop-coated on a pre-cleaned ITO surface, and dried under an infrared lamp; and then the Nb2C MXene dispersion was drop-coated on the Mo-W 18 O 49 / ITO surface, and dried under an infrared lamp, denoted as Nb2C / Mo-W 18 O 49 / ITO photoanode.

[0014] (3) Preparation of photo-assisted enhanced self-powered electrochemical sensor:

[0015] First, a chitosan solution was drop-coated on the Nb2C MXene / Mo-W 18 O 49 composite electrode prepared in step (2), and naturally dried at room temperature for 3 h; and then an activated MC-RR aptamer solution was drop-coated on the photoanode surface, and dried at room temperature overnight, to obtain an apta / Nb2C / Mo-W 18 O 49 / ITO.

[0016] (4) The anode apta / Nb2C / Mo-W 18 O 49 / ITO, the cathode platinum sheet and the single-chamber quartz electrolytic cell were assembled into a self-powered sensor.

[0017] Further, in step (1), the mass percentage of MoCl5 to WCl6 is 0.5-4%, preferably 1-4%, more preferably 1-2%.

[0018] Further, in step (2), the mass ratio of Mo-W 18 O 49 and Nb2C MXene is 1:1. The drop-casting amount is 0.04 mg / cm2. 18 O 49 The concentration of the dispersion liquid is 2 mg / ml, and the drop-casting amount is 20 μL / cm 2 ; the concentration of the Nb2C MXene dispersion liquid is 2 mg / ml, and the drop-casting amount is 20 μL / cm 2 .

[0019] Further, in step (3), the concentration of the chitosan solution is 0.1%. The drop-casting volume ratio of the chitosan solution to the MC-RR aptamer solution is 1:1. The molar concentration of the MC-RR aptamer solution is 1-5 μmol / L, preferably 3 μmol / L. The drop-casting amount of the MC-RR aptamer solution is 20-60 μL / cm 2 , preferably 20 μL / cm 2 .

[0020] Further, the MC-RR aptamer nucleotide sequence in step (3) is: 5'-CAG CTC AGA AGC TTG ATC CTA CTG CCC TTC AAT GTT CAC TCC TGT TTC CTG ATC TTT GTC GAC TCG AAG TCG TGC ATC TG-3'.

[0021] The third object of the present application is to provide the application of the above-mentioned light-assisted self-powered sensor in detecting MC-RR. The specific detection steps are as follows:

[0022] S1, preparing a solution containing different concentrations of MC-RR;

[0023] Accurately weigh a certain mass of MC-RR, and use deionized water to prepare a standard solution with a concentration of 1.0×10 -4 mol / L. Dilute the standard solution with deionized water step by step to obtain a series of MC-RR standard solutions with different concentrations, with a concentration range of 1.0×10 -15 mol / L to 1.0×10 -9 mol / L.

[0024] S2, drawing a standard curve:

[0025] A series of known concentrations of MC-RR are dropped on the surface of the prepared photoanode material, and naturally dried at room temperature;

[0026] A 0.5 M Na2SO4 solution is used as an electrolyte, the current of the xenon lamp light source is kept at 20 A, the horizontal distance between the light source outlet and the ITO conductive surface is kept at 10 cm, the photocurrent size is measured at a test potential of 0 V, the linear relationship between the photocurrent intensity after adding MC-RR and the logarithmic value of the concentration of MC-RR is established, and the corresponding linear regression equation is obtained;

[0027] S3, sample detection, impurities are removed by filtering the sample, the photocurrent value is obtained by testing according to the above step 2, and the linear regression equation obtained in step 2 is used to calculate the photocurrent value, so as to obtain the concentration of MC-RR in the sample.

[0028] The beneficial effects of the present application are:

[0029] The present application assembles platinum sheets and Mo-W 18 O 49 / Nb2C MXene anode, develops a new type of self-powered photoelectrochemical sensor, and establishes an electrochemical detection method for MC-RR, which has the following characteristics and advantages:

[0030] (1) The present application assembles platinum sheets and Mo-W 18 O 49 / Nb2C MXene anode, and constructs a new type of self-powered photoelectrochemical sensor. Mo atoms can provide abundant active sites, and at the same time, Mo doping enhances the metal-oxygen covalent bond, which can promote the transfer of electrons from the active sites. Doping Mo atoms into W 18 O 49 can polarize molecules and promote electron transfer, and the Fermi level of Nb2C MXene is low, which has higher conductivity and can significantly improve the sensitivity of the sensor. After coupling with MC-RR aptamer, the target can be specifically captured on the electrode, and the steric hindrance is increased, so that the sensitive detection of MC-RR is realized.

[0031] (2) Compared with the traditional detection method, the photoelectrochemical detection method proposed in the present application has the characteristics of simple and flexible operation, simple instrument and equipment, high sensitivity, wide linear range, low detection limit, low detection cost, etc. BRIEF DESCRIPTION OF DRAWINGS

[0032] The present application will be further described below in combination with the drawings and examples.

[0033] Figure 1 is an anode MC-RR / apta / Nb2C / Mo-W 18 O 49Assembly process and working mode diagram of a self-powered sensor composed of ITO and a platinum cathode sheet;

[0034] Figure 2 It is W 18 O 49 (Left, 20μm), Mo-W 18 O 49 (middle, 20 μm) and Mo-W 18 O 49 Scanning electron microscope image of / Nb2C (right, 20 μm);

[0035] Figure 3 The effect of different Mo doping contents on the photocurrent of the sensor (a: 0, b: 0.5%, c: 1%, d: 2%, e: 4%).

[0036] Figure 4 The effect of different concentrations of Na2SO4 solution on the photocurrent of the sensor;

[0037] Figure 5 This is a comparison of photocurrent values ​​before and after drop-coating 20 μL of aptamers with concentrations of (a) 1 μM, (b) 2 μM, (c) 3 μM, (d) 4 μM, and (e) 5 μM.

[0038] Figure 6 This is a comparison graph of photocurrent values ​​of MC-RR at different incubation times;

[0039] Figure 7 It is Nb2C / Mo-W 18 O 49 / ITO, apta / Nb2C / Mo-W 18 O 49 / ITO and MC-RR / apta / Nb2C / Mo-W 18 O 49 / Photocurrent curves during the fabrication of aptamer sensors using ITO;

[0040] Figure 8 These are photocurrent graphs of MC-RR at different concentrations, where the concentrations of MC-RR are ranked from highest to lowest (a→g:10). -15 -10 -9 );

[0041] Figure 9 It is a standard curve of photocurrent value after adding MC-RR versus the logarithm of MC-RR concentration. Detailed Implementation

[0042] The invention will now be described in further detail with reference to embodiments.

[0043] The raw materials and reagents used in the following specific examples of the present application can be commercially purchased unless otherwise specified. The Nb2C MXene used in the present application was purchased from Foshan Xinyan Technology Co., Ltd.; molecular weight: 158; concentration: 5 mg / mL, which was diluted to 2 mg / mL with pure water when used. Example 1

[0044] Nb2C / Mo-W 18 O 49 The preparation of the ITO photoanode, the specific steps are as follows:

[0045] 50 mg of WCl6 was dissolved in 34 mL of ethanol, then stirred vigorously for 30 min to prepare a transparent light yellow solution. Then, 1 mL of ethanol solution containing different amounts of MoCl5 (0 mg, 0.25 mg, 0.5 mg, 1 mg, 2 mg) was added to the solution, and further stirred for 10 min to obtain a mixture. Then the mixture was transferred to a 50 mL teflon-lined autoclave, sealed and heated at 200℃ for 12 hours. After the autoclave was cooled to room temperature, the synthesized product was centrifuged and washed with anhydrous ethanol several times. Finally, the product was dried in a vacuum oven at 60℃ for 10 hours.

[0046] 2 mg of synthesized Mo-W 18 O 49 The nanomaterials were dispersed in 1 mL of DMF (N, N-dimethylformamide) solution, ultrasonically mixed uniformly, and 20 μL was dropped on the ITO electrode with an area of 1 × 1 cm 2 , After drying under an infrared lamp, 20 μL of Nb2C MXene (2 mg / mL) dispersion was dropped on the ITO surface, and the infrared lamp was continued to dry, which was represented as Nb2C / Mo-W 18 O 49 / ITO photoanode.

[0047] Figure 2 From left to right are W 18 O 49 , Mo-W 18 O 49 and Mo-W 18 O 49 / Nb2C scanning electron microscope images; from Figure 2 It can be seen that the morphology of W 18 O 49 is nanowire, and the morphology of W 18 O 49 does not change after doping Mo atoms, because doping Mo atoms changes the W 18 O 49The surface atomic structure and electronic state of W, therefore, will not cause W 18 O 49 The morphological changes can be observed in the scanning electron microscope images of the composite material, where nanowires are distributed around the sheet-like structure.

[0048] Figure 3 The effect of different Mo doping contents on the photocurrent of the sensor was studied, from... Figure 3 It can be seen that when the Mo content increases from 0 to 1%, the photocurrent gradually increases. As the Mo content further increases, the photocurrent gradually decreases. Therefore, the optimal Mo doping content is 1%. Example 2

[0049] Nb2C / Mo-W 18 O 49 The preparation of the ITO photoanode was the same as in Example 1. Using Nb₂C / Mo-W 18 O 49 A photoelectric self-powered system was prepared using ITO as the anode and a platinum sheet as the cathode. The system was placed in Na₂SO₄ solutions with concentrations ranging from 0.3 to 0.7 mol / L, with Na₂SO₄ solution serving as the electrolyte. The effect of different Na₂SO₄ concentrations on the photocurrent of the sensor was investigated, and the results are shown below. Figure 4 .from Figure 4 It can be seen that the sensor has the highest photocurrent value when the Na2SO4 solution concentration is 0.5 mol / L. Example 3

[0050] Nb2C / Mo-W 18 O 49 The preparation of the ITO photoanode was the same as in Example 1. 20 μL of 0.1% chitosan solution was drop-coated onto the Nb2C / Mo-W... 18 O 49 / ITO anode surface, air-dry at room temperature for 3 hours. Aptamer activation: Vortex the MC-RR aptamer for 5 minutes, then centrifuge at 8000 rpm for 20 minutes. Add a stock solution containing 0.2 mol / L KCl, 0.1 mol / L NaCl, 5.0 mmol / L MgCl2·6H2O, and 1.0 mmol / L EDTA in 0.05 mol / L Tris-HCl buffer solution. After homogenization, obtain an aptamer solution with a concentration of 10 μmol / L, and then dilute to 1 μM, 2 μM, 3 μM, 4 μM, and 5 μM as needed. Drop 20 μL of the activated MC-RR aptamer solution onto Nb2C / Mo-W 18 O 49ITO anode surface, dried at room temperature overnight to obtain apta / Nb2C / Mo-W 18 O 49 ITO. The anode apta / Nb2C / Mo-W 18 O 49 ITO, the cathode platinum sheet and single-chamber quartz electrolytic cell were assembled into a self-powered photoelectrochemical sensor, and the values of photocurrent were observed after dropping different concentrations of MC-RR aptamer. From Figure 5 It can be seen that when the concentration of aptamer increases from 1 μmol / L to 3 μmol / L, the photocurrent value gradually increases, and with the further increase of the concentration of aptamer, the photocurrent value tends to be stable. Therefore, the optimal aptamer concentration is 3 μmol / L. Example 4

[0051] Nb2C / Mo-W 18 O 49 The preparation of the anode ITO was the same as in Example 1. 20 μL of 0.1% chitosan solution and 20 μL of 2 μM MC-RR aptamer solution were dropped on the surface of Nb2C / Mo-W 18 O 49 ITO cathode surface, dried at room temperature overnight to obtain apta / Nb2C / Mo-W 18 O 49 ITO. Prepare MC-RR solution, accurately weigh a certain mass of MC-RR, and use deionized water to prepare 1×10 -10 mol / L MC-RR solution, drop 20 μL of MC-RR solution on the surface of apta / Nb2C / Mo-W 18 O 49 ITO electrode, incubate for 5-40 min respectively to prepare MC-RR / apta / Nb2C / Mo-W 18 O 49 ITO; with MC-RR / apta / Nb2C / Mo-W 18 O 49 ITO as the anode and platinum sheet as the cathode, a self-powered system was formed, and the change of photocurrent after MC-RR incubation for different time was observed, and the results are shown in Figure 6 From Figure 6 It can be seen that within the range of 5-20 min, with the increase of incubation time, the photocurrent value increases significantly, and then reaches the maximum value. When the incubation time is more than 20 min, the photocurrent value begins to gradually decrease and tends to be stable. Therefore, 20 min is the most suitable detection binding time in this experiment.

[0052] Figure 7 Nb2C / Mo-W 18 O 49 / ITO, apta / Nb2C / Mo-W 18 O 49 / ITO and MC-RR / apta / Nb2C / Mo-W 18 O 49 / ITO photocurrent curves during the fabrication of aptamer sensor. Example 5

[0053] As Figure 1 shown, the photo-assisted enhanced self-powered electrochemical sensor was composed of a platinum sheet as the cathode, Nb2C / Mo-W 18 O 49 / ITO as the anode to form a self-powered system for MC-RR detection.

[0054] The preparation method of the photo-assisted enhanced self-powered electrochemical sensor has the following steps:

[0055] (1) Preparation of Mo-W 18 O 49 :

[0056] 50 mg of WCl6 was dissolved in 34 mL of ethanol, then stirred vigorously for 30 min to prepare a transparent light yellow solution. Then, 1 mL of ethanol solution containing different amounts of MoCl5 was added to the solution, and further stirred for 10 min. Then the mixture was transferred to a 50 mL teflon-lined autoclave, sealed and heated at 200°C for 12 hours. After the autoclave was cooled to room temperature, the synthesized product was centrifuged and washed with anhydrous ethanol several times. Finally, the product was dried in a vacuum oven at 60°C for 10 hours.

[0057] (2) Preparation of photo-anode:

[0058] 2 mg of synthesized Mo-W 18 O 49 nanomaterials were dispersed in 1 mL of DMF (N, N-dimethylformamide) solution, ultrasonically mixed uniformly, and 20 μL was dropped on the ITO electrode with an area of 1 × 1 cm 2 , dried under an infrared lamp, and then 20 μL of Nb2C MXene (2 mg / mL) dispersion was dropped on the ITO surface and dried under an infrared lamp, denoted as Nb2C / Mo-W 18 O 49 / ITO photo-anode.

[0059] (3) Preparation of photo-assisted enhanced self-powered electrochemical sensor:

[0060] First, the chitosan solution was dropped on the Nb2C MXene / Mo-W18 O 49 The complex electrode was dried naturally at room temperature for 3 h, and then the activated MC-RR aptamer solution was dropped on the surface of the photoanode and dried at room temperature overnight. Finally, the anode apta / Nb2C / Mo-W 18 O 49 / ITO, the cathode platinum sheet and the single-chamber quartz electrolytic cell were assembled into a self-powered sensor.

[0061] (4) Drawing of standard curve:

[0062] The MC-RR solution was prepared. A certain amount of MC-RR was accurately weighed, and deionized water was used to prepare a standard solution of 1.0×10 -4 mol / L. The standard solution was sequentially diluted with deionized water to obtain a series of MC-RR standard solutions with different concentrations. In the light-assisted enhanced self-powered electrochemical sensor, a platinum sheet was used as the cathode, and Nb2C / Mo-W 18 O 49 was used as the anode to form a self-powered system for MC-RR detection. As shown in Figure 8 , the concentrations of MC-RR from low to high according to the peak values of the curve are as follows:

[0063] 1×10 -15 mol / L, 1×10 -14 mol / L, 1×10 -13 mol / L, 1×10 -12 mol / L, 1×10 -11 mol / L, 1×10 -10 mol / L, and 1×10 -9 mol / L.

[0064] The MC-RR standard solutions with different concentrations (1×10 -15 mol / L, 1×10 -14 mol / L, 1×10 -13 mol / L, 1×10 -12 mol / L, 1×10 -11 mol / L, 1×10 -10 mol / L, and 1×10 -9 mol / L) were dropped on the above-mentioned apta / Nb2C / Mo-W 18 O 49 electrode, incubated for 20 minutes, and 0.5 M Na2SO4 solution was used as the electrolyte. Then, a linear relationship between the photocurrent value and the logarithmic value of the concentration of MC-RR was established, and the corresponding linear regression equation was I=-0.04618-0.01637log[CMC-RR (nM)] with a correlation coefficient (R 2 ) of 0.994; the linear regression equation had a detection range of 1 x 10 -15 mol / L to 1 x 10 -9 mol / L, and a minimum detection limit of 9.3 x 10 -16 mol / L.

[0065] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, according to the technical solution and concept of the present application, makes equivalent replacement or change within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A light-assisted enhanced self-powered electrochemical sensor, characterized in that, With Nb2C / Mo-W 18 O 49 The nanocomposite material serves as the substrate, and is co-modified with a specific recognition element aptamer on the conductive surface of indium tin oxide conductive glass; the Mo-W 18 O 49 Preparation method: A WCl6 ethanol solution and a MoCl5 ethanol solution were mixed thoroughly to obtain a mixed solution. The mixed solution was transferred to a reaction vessel, sealed, and heated at 150-200℃ for 10-12 hours. After cooling to room temperature, the product was collected by centrifugation and washing several times, and then dried to obtain Mo-WCl6. 18 O 49 Nanomaterials; the mass percentage of MoCl5 and WCl6 is 0.5-4%; The method for preparing the light-assisted enhanced self-powered electrochemical sensor specifically includes the following steps: (1) Place Mo-W 18 O 49 Nanomaterials were dispersed in N,N-dimethylformamide and ultrasonically mixed to obtain Mo-W 18 O 49 Dispersion; take Mo-W 18 O 49 The dispersion was drop-coated onto the ITO electrode and dried; then, the Nb₂C MXene dispersion was drop-coated onto the ITO electrode surface and dried, denoted as Nb₂C / Mo-W. 18 O 49 / ITO; (2) Add the chitosan solution dropwise to the Nb2C / Mo-W prepared in step (1). 18 O 49 On an ITO electrode, the mixture is allowed to air dry at room temperature, then an activated MC-RR aptamer solution is drop-coated onto it and dried at room temperature to obtain apta / Nb2C / Mo-W. 18 O 49 / ITO; (3) Add apta / Nb2C / Mo-W 18 O 49 ITO is used as the photoelectric anode, a platinum cathode, and a single-chamber quartz electrolytic cell to assemble a self-powered sensor.

2. The method for preparing the light-assisted enhanced self-powered electrochemical sensor according to claim 1, characterized in that, Specifically, the steps include the following: (1) Place Mo-W 18 O 49 Nanomaterials were dispersed in N,N-dimethylformamide and ultrasonically mixed to obtain Mo-W 18 O 49 Dispersion; take Mo-W 18 O 49 The dispersion was drop-coated onto the ITO electrode and dried; then, the Nb₂C MXene dispersion was drop-coated onto the ITO electrode surface and dried, denoted as Nb₂C / Mo-W. 18 O 49 / ITO; (2) Add the chitosan solution dropwise to the Nb2C / Mo-W prepared in step (1). 18 O 49 On an ITO electrode, the mixture is allowed to air dry at room temperature, then an activated MC-RR aptamer solution is drop-coated onto it and dried at room temperature to obtain apta / Nb2C / Mo-W. 18 O 49 / ITO; (3) Add apta / Nb2C / Mo-W 18 O 49 ITO is used as the photoelectric anode, a platinum cathode, and a single-chamber quartz electrolytic cell to assemble a self-powered sensor.

3. The method for preparing the light-assisted enhanced self-powered electrochemical sensor according to claim 2, characterized in that, In step (1), Mo-W 18 O 49 The mass ratio of Nb2C MXene to Nb2C MXene was 1:

1.

4. The method for preparing the light-assisted enhanced self-powered electrochemical sensor according to claim 2, characterized in that, In step (1), Mo-W 18 O 49 The concentration of the dispersion was 2 mg / ml, and the drop volume was 20 μL / cm. 2 The concentration of the Nb2C MXene dispersion was 2 mg / ml, and the drop volume was 20 μL / cm. 2 .

5. The method for preparing the light-assisted enhanced self-powered electrochemical sensor according to claim 2, characterized in that, The nucleotide sequence of the MC-RR aptamer in step (2) is: 5'-CAG CTC AGA AGC TTG ATC CTA CTG CCC TTCAAT GTT CAC TCC TGT TTC CTG ATC TTT GTC GAC TCG AAG TCG TGC ATC TG-3'.

6. The method for preparing the light-assisted enhanced self-powered electrochemical sensor according to claim 2, characterized in that, In step (2), the concentration of MC-RR aptamer is 1~5 μmol / L, and the drop volume of MC-RR aptamer solution is 20 μL / cm. 2 .

7. The method for preparing the light-assisted enhanced self-powered electrochemical sensor according to claim 2, characterized in that, In step (2), the mass percentage concentration of the chitosan solution is 0.1%; the volume ratio of chitosan to MC-RR aptamer is 1:

1.

8. The application of the light-assisted enhanced self-powered electrochemical sensor as described in claim 1 in MC-RR detection, characterized in that, Application method: Drop the sample to be tested onto apta / Nb2C / Mo-W 18 O 49 On ITO, the modified electrode MC-RR / apta / Nb2C / Mo-W was obtained by natural incubation at room temperature. 18 O 49 / ITO; with MC-RR / apta / Nb2C / Mo-W 18 O 49 ITO is used as the working electrode for photoelectrochemical testing, a platinum sheet is used as the counter electrode, and Na2SO4 solution is used as the electrolyte to form a photoelectrochemical self-powered system. The concentration of MC-RR in the sample is quantitatively detected by the photocurrent-logarithmic concentration standard curve method.

9. The application of the light-assisted enhanced self-powered electrochemical sensor according to claim 8 in MC-RR detection, characterized in that, The concentration of the Na2SO4 solution is 0.5 mol / L; the incubation time is 20-40 min; the photocurrent test method is as follows: keep the xenon lamp source current at 20 A, keep the horizontal distance between the light source outlet and the ITO conductive surface at 10 cm, and measure the photocurrent at a test potential of 0 V.

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