An aluminum-air battery enhanced photoelectrochemical self-powered sensor and a preparation method and application thereof

Abstract

The application belongs to the field of electrochemical detection, and particularly relates to a construction method of a photoelectrochemical self-powered sensor based on aluminum-air battery enhancement and application in detection of microcystin-RR. A CuO film is prepared through electrodeposition annealing conversion, CeO2-Ti3C2 nano composite material is loaded, and MC-RR aptamer is modified on the electrode to prepare a photo-cathode apta / CeO2-Ti3C2 / CuO / FTO. The aluminum anode, single-chamber quartz electrolytic cell and photo-cathode apta / CeO2-Ti3C2 / CuO / FTO are assembled to construct a self-powered sensor, and a relationship between sensor performance and microcystin-RR concentration is established to achieve the purpose of rapid, sensitive and specific detection.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical detection, and specifically relates to a photoelectrochemical self-powered sensor based on an aluminum-air battery, its preparation method, and its application in the detection of microcystin-RR. Background Technology

[0002] Microcystins (MCs) are cyclic heptacapeptide toxins produced as secondary metabolites of the cyanobacteria genus *Microcystis*. They exhibit hepatotoxicity, neurotoxicity, immunotoxicity, and reproductive toxicity, and are also confirmed promoters of liver cancer. More than 70 structural variants of MCs are known, with MC-LR, MC-RR, and MC-YR being among the most abundant and toxic. Currently, most attention is focused on MC-LR, which is the most toxic and abundant. However, although MC-RR is less toxic than MC-LR, its higher concentration may pose a greater risk.

[0003] Currently, detection methods for MC-RR include protein phosphatase inhibition assay (PPIA), enzyme-linked immunosorbent assay (ELISA), high-performance liquid chromatography-mass spectrometry (HPLC-MS), and high-performance liquid chromatography (HPLC). However, the PPIA method uses expensive instruments and lacks specificity; ELISA is for single use and has a limited detection range; HPLC-MS involves complex sample preparation, is time-consuming, and has high detection costs; while HPLC does not meet the required sensitivity, requires sample concentration, has cumbersome pretreatment, and generates a large amount of toxic organic waste liquid, making it time-consuming, labor-intensive, and expensive.

[0004] Patent CN114527176A discloses a photoelectrochemical biosensor (PEC) constructed using TiO2 / Ti3C2 and MoS2 / Ti3C2 composites as photoelectroactive materials for photoelectrochemical detection of MC-RR. Compared with traditional PEC sensors, self-powered sensors based on photofuel cells (PFCs) have attracted widespread attention due to their advantages of simple operation, low cost, fast response speed, and integration with other technologies, requiring no external power source and consisting of dual electrodes. Currently, self-powered sensors based on photofuel cells, biofuel cells, and enzyme fuel cells have been researched and proposed. Among them, self-powered sensors based on photofuel cells (PFCs) stand out due to their advantages such as no secondary pollution, fast response speed, and high stability. However, the relatively low open-circuit voltage and output power density result in a narrow detection range and limited sensitivity, which to some extent limits the application of PFC-type self-powered sensors. In recent years, metal-air batteries (MABs) have attracted attention due to their high open-circuit voltage and high energy density. Among various metal-air batteries, zinc-air batteries have received the most widespread attention. Aluminum-air batteries operate on a similar principle to zinc-air batteries. However, compared to zinc anodes, aluminum is a cheaper, safer, and more environmentally friendly metal, effectively reducing costs. Furthermore, aluminum-air batteries offer advantages such as higher specific energy density and higher specific power density.

[0005] The oxygen reduction reaction (ORR) is the most important factor determining the overall electrochemical performance of metal-air batteries. Introducing a photocathode into an aluminum-air battery allows the photocathode to generate electrons and holes under light irradiation, converting solar energy into electrochemical energy and promoting the ORR, thereby increasing the open-circuit voltage and power density. P-type semiconductors are typically chosen as photosensitive materials for the photocathode. CuO, as a classic p-type semiconductor, has advantages such as narrow bandgap, low cost, and low toxicity. However, CuO suffers from low conductivity and low carrier mobility under light irradiation, limiting its widespread application. To overcome these drawbacks, forming a heterojunction between CuO and semiconductor materials to promote the transport of photogenerated electrons and holes is an effective strategy. CeO2, as the most widely used rare-earth oxide, has attracted increasing attention due to its visible light absorption and excellent catalytic activity. To date, some reports have demonstrated that CeO2 can serve as a photoactive material for PEC. Due to their energy level crossover, CuO and CeO2 hold promise for forming a highly efficient heterostructure. Furthermore, CeO2 can be used in Ce... 3+ / Ce 4+ The process exhibits a reversible transition and the adsorption of oxygen by oxygen vacancies in CeO2, thereby promoting the ORR reaction. Summary of the Invention

[0006] The purpose of this invention is to provide a photoelectrochemical self-powered sensor based on an aluminum-air battery, its preparation method, and its application in the detection of microcystin-releasing factor (MC-RR). This invention uses a CeO2-Ti3C2 / CuO composite material as the substrate, and an aptamer (apta) with specific recognition function as the recognition unit, both modified on the conductive surface of a functional glass (FTO). Apta / CeO2-Ti3C2 / CuO is designated as the cathode in the photoelectrochemical test, and an aluminum sheet is used as the anode, enabling rapid quantitative detection of MC-RR.

[0007] The solution adopted by this invention to solve its technical problem is:

[0008] A method for constructing a photoelectrochemical self-powered sensor based on an aluminum-air battery enhancement includes the following steps:

[0009] (1) A Cu2O thin film is deposited on the FTO surface by electrochemical deposition, and then converted into a CuO thin film by high-temperature annealing, thus obtaining a CuO / FTO electrode; specifically,

[0010] The FTO electrode was ultrasonically cleaned in NaOH solution, followed by heating and boiling, and then cleaned in acetone, ethanol, and ultrapure water, respectively. Copper sulfate and lactic acid were dissolved in deionized water, and the pH was adjusted to alkalinity with sodium hydroxide solution to prepare the electroplating solution. A Cu₂O film was deposited on the FTO surface at 60°C for 10 min using electrochemical deposition at a bias of -0.5 V (vs. Ag / AgCl). The FTO substrate was then rinsed with deionized water and ethanol and dried at room temperature to obtain the Cu₂O film. The prepared Cu₂O film was annealed to convert it into a CuO film.

[0011] Furthermore, the concentration of copper sulfate is 0.1 M; the concentration of lactic acid is 3 M.

[0012] Furthermore, the pH value of the electroplating solution is 11.

[0013] Furthermore, the high-temperature annealing reaction temperature is 490–510 °C, the reaction time is 2 h, and the heating rate is 5 °C / min.

[0014] (2) Preparation of CeO2-Ti3C2 nanocomposite materials:

[0015] Ti3C2 MXene nanosheets were dispersed in H2O, and then Ce(NO3)3·6H2O was added to the dispersion and stirred. Further, Ce-containing... 3+A suspension of MXene nanosheets was injected into an aqueous NaOH solution under vigorous stirring. The mixture was then transferred to a high-pressure reactor for hydrothermal reaction. After the reaction was completed, the mixture was allowed to cool naturally, washed with pure water, and dried.

[0016] Furthermore, the concentration of the NaOH aqueous solution is 20 M; in the prepared CeO2-Ti3C2 nanocomposite material, Ti3C2 accounts for 10% to 20% of the mass percentage of CeO2.

[0017] Furthermore, the hydrothermal reaction temperature is 170–190°C, the reaction time is 22–26 h, and the drying temperature is 50–70°C.

[0018] (3) CeO2-Ti3C2 nanocomposite material was dispersed in N,N-dimethylformamide (DMF) to prepare CeO2-Ti3C2 dispersion; CeO2-Ti3C2 dispersion was coated on CuO / FTO surface and dried to obtain CeO2-Ti3C2 / CuO / FTO photocathode;

[0019] Furthermore, the CeO2-Ti3C2 dispersion concentration is 2 mg / mL, and the coating amount is 80 μL / cm. 2 .

[0020] (4) The aptamer solution is drop-coated onto the surface of CeO2-Ti3C2 / CuO / FTO photocathode and incubated at room temperature to obtain apta / CeO2-Ti3C2 / CuO / FTO;

[0021] Furthermore, the concentration of the MC-RR aptamer is 3 M, and the dropping volume is 20 μL / cm. 2 The aptamer incubation time is 20 min.

[0022] Furthermore, the MC-RR aptamer nucleotide sequence is shown below:

[0023] Aptamer: 5'-CAG CTC AGA AGC TTG ATC CTA CTG CCC TTC AAT GTT CAC TCC TGTTTC CTG ATC TTT GTC GAC TCG AAG TCG TGC ATC TG-3'.

[0024] (5) Assemble an aluminum anode, a single-chamber quartz electrolytic cell and a photocathode apta / CeO2-Ti3C2 / CuO / FTO to construct a photoelectrochemical self-powered sensor.

[0025] Furthermore, the aluminum sheets are polished with different grades of sandpaper before assembly to remove surface impurities and oxide layers.

[0026] The self-powered sensor prepared according to the above method is used in the photoelectrochemical detection of MC-RR. The specific detection method includes the following steps:

[0027] S1. Prepare phosphate-buffered saline (PBS) solution;

[0028] S2. Prepare microcystin MC-RR at different concentrations;

[0029] A precise amount of MC-RR was weighed and serially diluted with deionized water to obtain a series of microcystin standard solutions of different concentrations, ranging from 1.0 × 10⁻⁶. -14 mol / L ~ 1.0 × 10 -8 mol / L;

[0030] S3. Plotting the standard curve:

[0031] A series of MC-RR standard solutions of known concentrations were drop-coated onto the prepared electrode apta / CeO2-Ti3C2 / CuO / FTO and allowed to air dry at room temperature. The resulting modified electrode was labeled MC-RR / apta / CeO2-Ti3C2 / CuO / FTO.

[0032] Using MC-RR / apta / CeO2-Ti3C2 / CuO / FTO as the cathode working electrode and an aluminum sheet as the anode working electrode, a photoelectrochemical self-powered system was formed. PBS buffer solution was used as the electrolyte, the xenon lamp source current was kept at 20A, and the horizontal distance between the light source outlet and the FTO conductive surface was kept at 10cm. The power density was measured at a test potential of 0 V, and a series of corresponding relationships between MC-RR concentration and photoelectric power density were obtained. The standard curve of MC-RR was then calculated, and a linear relationship between the photoelectric power density output value after the addition of MC-RR and the logarithm of the MC-RR concentration was established, yielding the corresponding linear regression equation.

[0033] S4. Actual sample testing:

[0034] The actual sample is pretreated before testing, and then the pH value is adjusted. The calculation is performed based on the linear regression equation in step S3 above.

[0035] Preferably, in step S3, the pH of the PBS buffer solution is 7.4, the concentration is 0.1 mol / L, and the binding time between the analyte and the aptamer of the modified electrode MC-RR / apta / CeO2-Ti3C2 / CuO / FTO is 20 to 60 min.

[0036] The sensor's limit of detection for MC-RR solution concentration is 2.32 × 10⁻⁶. -15 M.

[0037] The advantages of this invention are as follows: Compared with traditional sensors, this invention has the following three advantages:

[0038] (1) This invention prepares a CeO2-Ti3C2 composite and CuO as photoelectric active materials to construct a photoelectrochemical self-powered sensor. The formation of a heterojunction promotes the transport of photogenerated electrons and holes, amplifying the power density response signal. Aluminum-air batteries can further improve open-circuit voltage and power density through light irradiation, and CeO2 can be used to... 3+ / Ce 4+ The reversible transformation and oxygen vacancies effectively promote the ORR reaction.

[0039] (2) In this invention, Ti3C2 is used to dope CeO2. On the one hand, the doping of semiconductor materials effectively promotes the separation of electrons and holes and broadens the absorption of visible light. On the other hand, by utilizing the specific recognition of aptamers and binding with MC-RR molecules, the steric hindrance effect is increased and the transfer of electrons is suppressed.

[0040] (3) The detection mode proposed in this invention achieves ultrasensitive detection of MC-RR, within 10 -14 ~10 -8 Within the concentration range of mol / L, the MC-RR concentration showed a linear relationship, with a detection limit of up to 2.32 × 10⁻⁶. -15 mol / L.

[0041] (4) Compared with traditional detection methods, the photoelectrochemical detection method of MC-RR proposed in this invention has the advantages of simpler and more flexible operation, simpler instruments and equipment, wider detection range, lower detection limit and lower detection cost. Attached Figure Description

[0042] The present invention will be further described below with reference to the accompanying drawings and examples.

[0043] Figure 1 This is a schematic diagram illustrating the fabrication of the sensor and the detection of MC-RR in this invention.

[0044] Figure 2 The P-type CeO2-Ti3C2 / CuO / FTO photoanodes with different Ti3C2 ratios prepared in Example 1 are... max .

[0045] Figure 3 This is a graph showing the electrical power response of the sensor to different concentrations of MC-RR.

[0046] Figure 4 This is the standard curve of logarithmic concentration versus power density for MC-RR. Detailed Implementation

[0047] A method for fabricating a photoelectrochemical self-powered sensor and its application in MC-RR detection is disclosed. Using CeO2-Ti3C2 / CuO / FTO as the photocathode and an aluminum sheet as the anode electrode, a self-powered system is constructed to achieve specific detection of MC-RR. A schematic diagram of the sensor fabrication and MC-RR detection is shown below. Figure 1 As shown.

[0048] The present invention will be further described in detail below with reference to the embodiments.

[0049] Example 1:

[0050] The effects of CeO2-Ti3C2 / CuO / FTO photocathodes with different proportions of Ti3C2 on sensor performance were compared.

[0051] (1) Preparation of CuO thin film: CuO thin film is prepared by electrodeposition of Cu2O thin film and then annealed at high temperature.

[0052] The FTO electrode was ultrasonically cleaned in 1M NaOH solution for 30 min, followed by heating and boiling for 30 min, and then cleaned in acetone, ethanol, and ultrapure water for 30 min each. An electroplating solution was prepared by dissolving 10 mmol of copper sulfate and 0.3 mol of lactic acid in 100 mL of deionized water and adjusting the pH to 11 with sodium hydroxide solution. A Cu2O film was prepared by electrodeposition of the FTO electrode at a bias of -0.5 V (vs. Ag / AgCl) for 10 min at 60 °C. The FTO substrate was then rinsed with deionized water and ethanol and dried at room temperature to obtain the Cu2O film. The prepared Cu2O film was annealed at 500 °C for 2 h to convert it into a CuO film.

[0053] (2) Preparation of CeO2-Ti3C2 nanocomposite materials:

[0054] Ti3C2 MXene nanosheets were dispersed in 10 mL of H2O, then 0.72 g of Ce(NO3)3·6H2O was added to the dispersion and stirred for 2 h. Subsequently, 24 g of NaOH was dissolved in 30 mL of distilled water. Further, Ce-containing... 3+A suspension of / MXene nanosheets was injected into a NaOH solution under vigorous stirring and stirred for 3 h. Then, the entire mixture was transferred to a high-pressure reactor and heated at 180 °C for 24 h. Finally, the resulting product was washed with pure water and dried at 60 °C to obtain a CeO2-Ti3C2 nanocomposite material. The CeO2-Ti3C2 nanocomposite material was dispersed in DMF to prepare a CeO2-Ti3C2 dispersion with a concentration of 2 mg / mL.

[0055] The Ti3C2 MXene nanosheets had masses of 8.6 mg, 17.1 mg, 28.5 mg, 42.8 mg, and 57.1 mg, respectively, and their mass ratios to CeO2 were 3%, 6%, 10%, 15%, and 20%, respectively.

[0056] (3) Preparation of CeO2-Ti3C2 / CuO / FTO photocathode:

[0057] 80 μL of CeO2-Ti3C2 dispersion (2 mg / mL) was coated onto CuO / FTO (1 cm⁻¹). 2 The surface is then vacuum dried, resulting in a CeO2-Ti3C2 / CuO / FTO photocathode.

[0058] CeO2-Ti3C2 / CuO / FTO with different proportions of Ti3C2 were used as photocathodes, and aluminum sheets were used as anodes. Before assembly, the aluminum sheets were polished with sandpaper of different grades to remove surface impurities and oxide layers. 0.1M PBS buffer solution with pH=7.4 was used as the electrolyte. A xenon lamp source current of 20A was selected, and the horizontal distance from the light source outlet to the FTO conductive surface was 10cm. The power response was measured at a test potential of 0V.

[0059] Depend on Figure 2 It can be seen that as the proportion of Ti3C2 increases from 3% to 10%, the power density P max The percentage of Ti3C2 continuously increases. When the proportion of Ti3C2 increases from 10% to 20%, P... max The change is no longer significant. Therefore, the optimal ratio of Ti3C2 is CeO2-10%Ti3C2 / CuO.

[0060] Example 2

[0061] A method for constructing a photoelectrochemical self-powered sensor based on an aluminum-air battery and its application in detecting microcystin includes the following steps:

[0062] (1) Preparation of CuO thin films:

[0063] CuO films were prepared by electrodeposition followed by high-temperature annealing. The FTO electrode was ultrasonically cleaned in 1 M NaOH solution for 30 min, then heated and boiled for 30 min, followed by cleaning in acetone, ethanol, and ultrapure water for 30 min each. 10 mmol of copper sulfate and 0.3 mol of lactic acid were dissolved in 100 mL of deionized water, and the pH was adjusted to 11 with sodium hydroxide solution. Using copper sulfate as the copper source, Cu(II) was reduced to Cu(I) at a specific cathode potential. Sodium hydroxide was used to adjust the pH to convert Cu(I) to Cu2O while preventing hydrogen evolution. Lactic acid was oxidized at the counter electrode (anode) to ensure a continuous electrolysis process. In electrodeposition, FTO was used as the substrate, and electrodeposition was performed at 60 °C with a bias of -0.5 V (vs. Ag / AgCl) for 10 min. The FTO substrate was then rinsed with deionized water and ethanol and dried at room temperature to obtain the Cu2O film. The prepared Cu2O film was annealed at 500 °C for 2 h to convert it into CuO film.

[0064] (2) Preparation of CeO2-Ti3C2 nanocomposite materials:

[0065] 28.5 mg of Ti3C2 MXene nanosheets (Guangzhou Foshan Xinxi Technology Co., Ltd.) were dispersed in 10 mL of H2O, then 0.72 g of Ce(NO3)3·6H2O was added to the dispersion and stirred for 2 h. Subsequently, 24 g of NaOH was dissolved in 30 mL of distilled water. Further, Ce-containing... 3+ A suspension of / MXene nanosheets was injected into a NaOH solution under vigorous stirring and stirred for 3 h. Then, the entire mixture was transferred to a high-pressure reactor and heated at 180 °C for 24 h. Finally, the resulting product was washed with pure water and dried at 60 °C to obtain a CeO2-Ti3C2 nanocomposite material. The CeO2-Ti3C2 nanocomposite material was dispersed in DMF to prepare a CeO2-Ti3C2 dispersion with a concentration of 2 mg / mL.

[0066] (3) Preparation of CeO2-Ti3C2 / CuO / FTO photocathode:

[0067] 80 μL of CeO2-Ti3C2 dispersion (2 mg / mL) was coated onto CuO / FTO (1 cm⁻¹). 2 The surface is then vacuum dried, resulting in a CeO2-Ti3C2 / CuO / FTO photocathode.

[0068] (4) Sensor fabrication

[0069] 20 μL of 3 M MC-RR aptamer solution was added to the CeO2-Ti3C2 / CuO / FTO photocathode, and the sensor was incubated overnight at room temperature. Before assembly, the aluminum sheet was polished with different grades of sandpaper to remove surface impurities and the oxide layer. Then, the aluminum anode, single-chamber quartz electrolytic cell, and photocathode apta / CeO2-Ti3C2 / CuO / FTO were assembled to construct a self-powered sensor. The photocathode apta / CeO2-Ti3C2 / CuO / FTO was incubated in the MC-RR aptamer solution at room temperature for 20 min, and then the electrode was rinsed with ultrapure water, thus creating a photoelectrochemical self-powered sensor for MC-RR detection.

[0070] The aptamer sequence of the above sensor is as follows: aptamer: 5'-CAG CTC AGA AGC TTG ATC CTACTG CCC TTC AAT GTT CAC TCC TGT TTC CTG ATC TTT GTC GAC TCG AAG TCG TGC ATCTG-3'.

[0071] (5) Plotting the standard curve:

[0072] Prepare a standard solution of MC-RR by adding a certain amount of MC-RR to deionized water (specifically, dissolve MC-RR in 10 ml of deionized water, and then dilute it stepwise with deionized water to obtain a series of MC-RR standard solutions of different concentrations); take 20 μL of known MC-RR standard solutions of different concentrations and drop them onto the prepared electrode apta / CeO2-Ti3C2 / CuO / FTO. The modified electrode is labeled as MC-RR / apta / CeO2-Ti3C2 / CuO / FTO.

[0073] A self-powered photoelectrochemical sensor, MC-RR / apta / CeO2-Ti3C2 / CuO / FTO, was used as the photocathode and an aluminum sheet as the anode to detect MC-RR. The binding time between the analyte and the aptamer on the modified electrode MC-RR / apta / CeO2-Ti3C2 / CuO / FTO in the self-powered photoelectrochemical sensor was 20 min, and the response value of the electrical power was detected using PBS buffer as the electrolyte.

[0074] Electrodes modified with different concentrations of MC-RR were used as working electrodes, denoted as MC-RR / apta / CeO2-Ti3C2 / CuO / FTO, with an aluminum sheet as the counter electrode. The concentrations of MC-RR were (1.0 × 10⁻⁶)⁻¹, respectively. -14 mol / L, 1.0×10 -13 mol / L, 1.0×10 -12mol / L, 1.0×10 -11 mol / L, 1.0×10 -10 mol / L, 1.0×10 -9 mol / L, 1.0×10 -8 The electrolyte was 0.1M PBS buffer (pH 7.4). A xenon lamp with a source current of 20A and a horizontal distance of 10cm from the light source outlet to the FTO conductive surface was selected. The power response was measured at a test potential of 0V. Figure 3 As shown, the concentrations of MC-RR, ranked from bottom to top according to the peak values ​​of the curves, are: 1.0 × 10⁻⁶ -14 mol / L, 1.0×10 -13 mol / L, 1.0×10 -12 mol / L, 1.0×10 -11 mol / L, 1.0×10 -10 mol / L, 1.0×10 -9 mol / L, 1.0×10 -8 mol / L.

[0075] The linear relationship between the logarithm of the obtained MC-RR concentration and the magnitude of the electrical power is as follows: Figure 4 As shown, the correlation coefficient (R) is 0.996, and the detection range of the linear regression equation is 1.0 × 10⁻⁶. -14 -1.0×10 -8 mol / L, the limit of detection is 2.32 × 10⁻⁶. -15 mol / L.

[0076] (6) Sample testing

[0077] A certain amount of wastewater after impurity removal was added to 0.1M PBS buffer at pH=7.4 for photoelectrochemical detection. The concentration of MC-RR in the sample was calculated according to the regression equation corresponding to step (5) above. The results are listed in Table 1.

[0078] Table 1. Determination results of MC-RR in water samples

[0079]

[0080] As shown in Table 1, the samples were tested in parallel three times, with a relative standard deviation of less than 5% and a spiked recovery rate ranging from 94% to 106%. This invention can be used to detect MC-RR in wastewater.

[0081] The preferred embodiments of the present invention described above are for illustrative purposes. Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical spirit of the present invention. The technical scope of the present invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing a photoelectrochemical self-powered sensor, characterized in that, Includes the following steps: (1) A Cu2O thin film is deposited on the FTO surface by electrochemical deposition, and then converted into a CuO thin film by high-temperature annealing to obtain a CuO / FTO electrode; (2) Disperse Ti3C2 MXene nanosheets in H2O, add cerium nitrate and stir to mix evenly to obtain a suspension; add NaOH aqueous solution to the suspension and stir evenly to obtain a mixture; transfer the mixture to a high-pressure reactor for hydrothermal reaction, and after the reaction is completed, cool naturally, wash and dry to obtain CeO2-Ti3C2 nanocomposite material; (3) CeO2-Ti3C2 nanocomposite material was dispersed in N,N-dimethylformamide to prepare CeO2-Ti3C2 dispersion; CeO2-Ti3C2 dispersion was coated on CuO / FTO surface and dried to obtain CeO2-Ti3C2 / CuO / FTO photocathode; (4) The aptamer solution was drop-coated onto the surface of CeO2-Ti3C2 / CuO / FTO photocathode and incubated at room temperature to obtain apta / CeO2-Ti3C2 / CuO / FTO; (5) Assemble an aluminum anode, a single-chamber quartz electrolytic cell and a photocathode apta / CeO2-Ti3C2 / CuO / FTO to construct a photoelectrochemical self-powered sensor.

2. The method for preparing the photoelectrochemical self-powered sensor according to claim 1, characterized in that, The specific steps of step (1) are as follows: copper sulfate and lactic acid are dissolved in deionized water, and the pH is adjusted to alkaline with sodium hydroxide solution to obtain an electroplating solution; at 60°C, electrodeposit is performed on the pre-cleaned FTO electrode surface for 10 min with a bias voltage of -0.5 V relative to the Ag / AgCl electrode potential; the FTO substrate is rinsed with deionized water and ethanol and dried at room temperature to obtain a Cu2O film; the prepared Cu2O film is annealed to convert it into a CuO film; the molar concentration of copper sulfate in the electroplating solution is 0.1 mol / L; the molar concentration of lactic acid is 3 mol / L; the annealing reaction temperature is 490~510°C, the reaction time is 2 h; and the heating rate is 5°C / min.

3. The method for preparing the photoelectrochemical self-powered sensor according to claim 1, characterized in that, In step (2), the molar concentration of the NaOH aqueous solution is 20 mol / L.

4. The method for preparing the photoelectrochemical self-powered sensor according to claim 1, characterized in that, The mass percentage of Ti3C2 to CeO2 in CeO2-Ti3C2 nanocomposites is 10% to 20%.

5. The method for preparing a photoelectrochemical self-powered sensor according to claim 1, characterized in that, In step (2), the hydrothermal reaction temperature is 170-190℃ and the reaction time is 22-26h; the drying temperature is 50-70℃.

6. The method for preparing the photoelectrochemical self-powered sensor according to claim 1, characterized in that, The CeO2-Ti3C2 dispersion had a mass concentration of 2 mg / mL and a drop volume of 80 μL / cm. 2 .

7. The method for preparing a photoelectrochemical self-powered sensor according to claim 1, characterized in that, The concentration of the aptamer solution was 3 mol / L, and the dropping volume was 20 μL / cm. 2 The incubation time is 20 min; the nucleotide sequence of the aptamer is: 5'-CAG CTC AGA AGC TTG ATC CTA CTG CCC TTC AAT GTT CAC TCC TGT TTC CTG ATC TTTGTC GAC TCG AAG TCG TGC ATC TG-3'.

8. A photoelectrochemical self-powered sensor, characterized in that, Prepared using the method described in any one of claims 1-7.

9. An application of the photoelectrochemical self-powered sensor as described in claim 8, characterized in that, Application of the photoelectrochemical self-powered sensor in the photoelectrochemical detection of microcystin-RR.

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