Photoanode based on modified fern-like bismuth vanadate photocatalytic nanomaterials and its preparation method and application

Abstract

The present invention discloses a photoanode based on a modified fern-shaped bismuth vanadate photocatalytic nanomaterial, a preparation method thereof, and an application thereof. The photoanode comprises a conductive substrate and a modified fern-shaped bismuth vanadate photocatalytic nanomaterial and a specific aptamer probe modified thereon. The preparation method comprises sequentially modifying the modified fern-shaped bismuth vanadate photocatalytic nanomaterial and the specific aptamer probe on a conductive substrate. The photoanode of the present invention has the advantages of large specific surface area, multiple active sites, strong light absorption capacity, wide light response range, low photogenerated electron-hole recombination rate, good conductivity, high photocatalytic activity, good stability, etc. When used as a working electrode of a photoelectric aptamer sensor, it can be directly used to detect environmental pollutants (such as bisphenol A), and has the advantages of high stability, wide detection range, low detection limit, etc., which is of great significance for guiding the effective removal of pollutants in the environment.

Description

Technical Field

[0001] The present invention belongs to the field of material technology and relates to a functional nanomaterial for detecting environmental pollutants, a preparation method thereof, and an application thereof. Specifically, the present invention relates to a photoanode based on a modified fern-like bismuth vanadate photocatalytic nanomaterial, a preparation method thereof, and an application thereof in detecting pollutants in a water environment. Background Art

[0002] The rapid development of industrialization and urbanization, coupled with the discharge of massive amounts of industrial and domestic wastewater, as well as the extensive use of fertilizers and pesticides, has resulted in the release of a large number of organic pollutants into the environment. Most of these organic compounds are toxic and readily bioaccumulate, and some are teratogenic, carcinogenic, and mutagenic, posing a significant threat to human health and terrestrial and aquatic organisms. Currently, water pollution has become a major public health concern, encompassing at least 58 toxic organic pollutants. For example, bisphenol A (BPA) is an endocrine disruptor with estradiol-like activity. Low doses can disrupt normal endocrine function, causing adverse effects such as metabolic disorders, precocious puberty, sperm abnormalities, and cancer. The widespread use of plastics containing BPA has reportedly led to significant exposure to BPA in the food chain, water, and soil. Furthermore, BPA can enter the human body through both dietary and non-dietary sources. Therefore, long-term exposure to BPA-contaminated environments can have catastrophic consequences. Therefore, accurately measuring the concentrations of organic pollutants such as BPA in the environment is crucial for their effective removal.

[0003] Bismuth vanadate (BiVO4) is an excellent optoelectronic nanomaterial due to its suitable energy bandgap (2.4 eV), excellent photochemical stability, and controllable morphology. However, existing BiVO4 materials still suffer from disadvantages such as low carrier mobility, short diffusion distance of photogenerated holes, and severe carrier recombination, resulting in low photoelectric conversion efficiency and still unable to achieve the desired detection effect. In addition, existing BiVO4 materials still have the following defects: small specific surface area, few active sites, weak light absorption capacity, narrow light response range, high photogenerated electron-hole recombination rate, poor photocatalytic activity, and poor stability. These defects make it difficult to improve the detection accuracy and sensitivity of existing BiVO4 materials as functional materials. At the same time, existing methods for introducing defects still have the disadvantages of complex processes, harsh processing conditions, and significant safety hazards. Moreover, the defect introduction process is prone to introducing defects deep into the crystal structure (internal layer), which not only easily destroys the original crystal structure and leads to poor stability, but also hinders the improvement of light absorption capacity and photoelectric conversion efficiency, resulting in poor photocatalytic activity. To date, there have been no reports on "fern-like BiVO4 materials and their applications in photoelectric aptamer sensors." Therefore, obtaining a photoanode with a large specific surface area, numerous active sites, strong light absorption, a wide light response range, a low photogenerated electron-hole recombination rate, good conductivity, high photocatalytic activity, and excellent stability is of great significance for constructing photoelectrochemical aptamer sensors with high stability, a wide detection range, and a low detection limit, and for detecting and effectively removing pollutants in the environment. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology and provide a photoanode based on modified fern-like bismuth vanadate photocatalytic nanomaterials with a large specific surface area, multiple active sites, strong light absorption capacity, a wide light response range, a low photogenerated electron-hole recombination rate, good conductivity, high photocatalytic activity and good stability. The present invention also provides a preparation method of a photoanode based on modified fern-like bismuth vanadate photocatalytic nanomaterials with mild reaction conditions, safety and reliability, simple process, convenient operation, low cost and high yield, as well as the application of the photoanode based on modified fern-like bismuth vanadate photocatalytic nanomaterials in detecting pollutants in the environment.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions.

[0006] A photoanode based on modified fern-like bismuth vanadate photocatalytic nanomaterials comprises a conductive substrate, wherein the modified fern-like bismuth vanadate photocatalytic nanomaterials are in-situ grown on the surface of the conductive substrate, wherein the modified fern-like bismuth vanadate photocatalytic nanomaterials comprise fern-like bismuth vanadate nanomaterials, wherein nitrogen elements and oxygen defects are introduced on the surface of the fern-like bismuth vanadate nanomaterials; and wherein the modified fern-like bismuth vanadate photocatalytic nanomaterials are modified with specific aptamer probes.

[0007] The above-mentioned photoanode based on modified fern-like bismuth vanadate photocatalytic nanomaterial is further improved, wherein the modified fern-like bismuth vanadate photocatalytic nanomaterial is prepared by calcining a fern-like bismuth vanadate nanomaterial under a nitrogen atmosphere; the fern-like bismuth vanadate nanomaterial is prepared by hydrothermal treatment of bismuth salt and vanadium salt as raw materials at a pH value of 3 to 4; bismuth vanadate nanoparticles are distributed on the surface of the fern-like bismuth vanadate nanomaterial; the conductive substrate is a fluorine-doped tin dioxide transparent conductive glass electrode; the DNA substrate chain of the specific aptamer probe has a nucleotide sequence shown in SEQ ID NO.1; and the 5' end of the DNA substrate chain is labeled with a carboxyl group.

[0008] As a technical concept, the present invention also provides a method for preparing the above-mentioned photoanode based on the modified fern-like bismuth vanadate photocatalytic nanomaterial, comprising the following steps:

[0009] S1. Dissolve a bismuth salt in water, add a vanadium salt, and stir to obtain a mixed solution;

[0010] S2. Adjusting the pH value of the mixed solution to 3-4, adding a conductive substrate, and performing a hydrothermal reaction to obtain a conductive substrate with fern-like bismuth vanadate nanomaterials in situ grown on the surface;

[0011] S3. Under a nitrogen atmosphere, heating the conductive substrate with the fern-like bismuth vanadate nanomaterial in situ grown on the surface obtained in step S2 to 350° C. to 650° C. and calcining the substrate to obtain a conductive glass with the modified fern-like bismuth vanadate photocatalytic nanomaterial in situ grown on the surface;

[0012] S4. Modify the specific aptamer probe on the modified fern-like bismuth vanadate photocatalytic nanomaterial on the surface of the conductive glass to obtain a photoanode based on the modified fern-like bismuth vanadate photocatalytic nanomaterial.

[0013] The above preparation method is further improved in that in step S3, the calcination temperature is 400°C to 600°C.

[0014] The above preparation method is further improved. In step S1, the mass fraction of the bismuth salt in the mixed solution is 1.25 mg / mL to 1.5 mg / mL, and the mass fraction of the vanadium salt is 1.5 mg / mL to 2.5 mg / mL; the bismuth salt is bismuth nitrate pentahydrate; the vanadium salt is sodium orthovanadate; and the stirring time is 5 min to 10 min.

[0015] The above preparation method is further improved, wherein in step S2, glacial acetic acid is used to adjust the pH value of the mixed solution; the conductive substrate further comprises the following treatments before use: placing the conductive glass in an acetone solution for ultrasonic cleaning, and immersing it in a mixed solution of hydrogen peroxide / sulfuric acid for 60s to 100s; the mass concentration of the acetone solution is ≥99.0%; the mixed solution of hydrogen peroxide / sulfuric acid is obtained by mixing a hydrogen peroxide solution and a sulfuric acid solution; the volume ratio of the hydrogen peroxide solution to the sulfuric acid solution is 1 to 2:3; the peroxide The mass concentration of the hydrogen solution is 30%; the mass concentration of the sulfuric acid solution is 98%; the thickness of the conductive substrate is 1.0 mm to 1.5 mm, the width is 15.0 mm to 20.0 mm, and the length is 45.0 mm to 50.0 mm; the temperature of the hydrothermal reaction is 180° C. to 200° C.; the hydrothermal reaction time is 10 h to 12 h; after the hydrothermal reaction is completed, the product is dried under vacuum conditions; the drying temperature is 45° C.; and the drying time is 5 h to 8 h.

[0016] The above preparation method is further improved in that in step S3, the calcination time is 2h to 3h.

[0017] The above preparation method is further improved, and step S4 includes the following steps:

[0018] (1) immersing the conductive glass obtained in step S3 and having the modified fern-like bismuth vanadate photocatalytic nanomaterial in situ grown on the surface thereof in a 3-aminopropyltriethoxysilane solution to obtain amino-functionalized conductive glass;

[0019] (2) adding the specific nucleic acid aptamer solution dropwise to the amino-functionalized conductive glass surface obtained in step (1) for incubation, so that the specific nucleic acid aptamer is modified on the modified fern-like bismuth vanadate photocatalytic nanomaterial, thereby obtaining a photoanode based on the modified fern-like bismuth vanadate photocatalytic nanomaterial.

[0020] The above preparation method is further improved, in step (1), the 3-aminopropyltriethoxysilane solution is prepared by mixing 3-aminopropyltriethoxysilane with water; the volume ratio of the 3-aminopropyltriethoxysilane to water is 1:5 to 1:10; and the soaking time is 5h to 10h.

[0021] The above preparation method is further improved, in step (2), the specific nucleic acid aptamer solution further includes the following treatment before use: the specific nucleic acid aptamer solution is mixed with a solution containing N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride for activation to obtain an activated specific nucleic acid aptamer solution; the volume ratio of the specific nucleic acid aptamer solution to the solution containing N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is 5: 2 to 5:1; the concentration of the specific nucleic acid aptamer solution is 3 μM; the concentration of N-hydroxysuccinimide in the solution containing N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is 1M to 4M, and the concentration of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is 2M to 6M; the activation is carried out at a temperature of 37°C; the activation time is 10h to 12h; the incubation is carried out at a temperature of 4°C; and the incubation time is 40min.

[0022] As a general technical concept, the present invention also provides an application of the above-mentioned photoanode based on modified fern-like bismuth vanadate photocatalytic nanomaterials or the photoanode based on modified fern-like bismuth vanadate photocatalytic nanomaterials prepared by the above-mentioned preparation method in detecting pollutants in the environment.

[0023] The above application is further improved, and the application includes the following steps:

[0024] (a) dropping a solution of a pollutant to be tested onto the surface of a photoanode for incubation, so that the specific aptamer probe on the surface of the photoanode specifically recognizes and captures the pollutant, thereby obtaining a photoanode with captured pollutants;

[0025] (b) The pollutant-captured photoanode obtained in step (a) is used as a working electrode, and a platinum electrode is used as a photocathode, placed in a PBS buffer solution to construct a two-electrode photoelectrochemical aptamer sensor, connected to a power supply, and subjected to an LSV test under light conditions to obtain the maximum power value of the pollutant solution to be tested;

[0026] (c) Calculating the concentration of the pollutant solution to be tested based on the maximum power value of the pollutant solution to be tested obtained in step (b) using a detection linear regression equation constructed based on the relationship between the concentration of the pollutant solution and the change in the maximum power value.

[0027] The above application is further improved in that, in step (a), the incubation is carried out at a temperature of 4°C; the incubation time is 30 minutes; when the pollutant in the pollutant solution to be detected is bisphenol A, the DNA substrate chain of the specific aptamer probe used has a nucleotide sequence shown in SEQ ID NO.1; the 5' end of the DNA substrate chain is labeled with a carboxyl group,

[0028] The above application is further improved. In step (c), when the pollutant in the pollutant solution to be detected is bisphenol A, the corresponding detection linear regression equation is:

[0029] P max =0.5527×lgC 双酚A +2.253 (1),

[0030] In formula (1), P max is the maximum power value, C 双酚A is the concentration of bisphenol A in the solution, in μM, R 2 =0.9922, the linear detection range is 0.1nM~100μM, and the detection limit is 0.025nM.

[0031] Compared with the prior art, the advantages of the present invention are:

[0032] (1) In view of the problems of small specific surface area, few active sites, weak light absorption ability, narrow light response range, low carrier mobility, short diffusion distance of photogenerated holes, high photogenerated electron-hole recombination rate, poor photocatalytic activity and poor stability of bismuth vanadate materials, and the resulting defects of poor stability, narrow detection range and poor detection sensitivity of photoelectrochemical aptamer sensors, the present invention creatively proposes a photoanode based on modified fern-like bismuth vanadate photocatalytic nanomaterials, comprising a conductive substrate, a modified fern-like bismuth vanadate photocatalytic nanomaterial in situ grown on the surface of the conductive substrate, the modified fern-like bismuth vanadate photocatalytic nanomaterials comprising fern-like bismuth vanadate nanomaterials, nitrogen elements and oxygen defects introduced on the surface of the fern-like bismuth vanadate nanomaterials, and a specific aptamer probe modified on the modified fern-like bismuth vanadate photocatalytic nanomaterials. Compared with other different shapes, the fern-shaped bismuth vanadate nanomaterial used in the present invention has the following advantages: as a nanomaterial with a unique fern-like biomimetic morphology, the fern-shaped bismuth vanadate nanomaterial has a larger specific surface area and more active sites. While providing a large number of active sites, it can also significantly shorten the diffusion distance of photogenerated carriers, which is beneficial to improving the separation efficiency of photogenerated carriers. It can also significantly improve the reaction kinetics and promote the full contact between the target pollutants in the solution and the material, thereby being more conducive to promoting the rapid contact of the material with the target pollutants. On this basis, in the present invention, nitrogen elements and oxygen defects are introduced on the surface of the fern-like bismuth vanadate nanomaterial, which can further bring the following advantages: oxygen defects are introduced on the surface of the fern-like bismuth vanadate nanomaterial. Oxygen defects, as an electron donor, can increase the majority of the carrier density and provide electron traps to promote the separation of photogenerated carriers in the fern-like bismuth vanadate nanomaterial. In addition, oxygen defects can also improve the electronic structure of BiVO4 "fern-like" nanomaterials by generating impurity energy levels near the conduction band (CB) or valence band (VB) edge, so that the fern-like bismuth vanadate nanomaterial has higher electrical conductivity and thermal stability, thereby also promoting the improvement of the light absorption capacity of the material, thereby significantly improving the light energy utilization rate and photogenerated carrier separation efficiency of the fern-like bismuth vanadate nanomaterial. At the same time, the doping of nitrogen elements can also introduce more active sites. More importantly, there is a synergistic promoting effect between nitrogen doping and oxygen defects, which can effectively reduce the band gap of the material, enhance the excitation of carriers to the conduction band, and facilitate the transfer of electrons in the redox reaction. Compared with existing conventional bismuth vanadate photocatalytic nanomaterials, the modified fern-shaped bismuth vanadate photocatalytic nanomaterial of the present invention has the advantages of large specific surface area, multiple active sites, strong light absorption ability, wide light response range, low photogenerated electron-hole recombination rate, good conductivity, high photocatalytic activity, and good stability. It is a new bismuth vanadate catalyst that can be widely used and has excellent performance.More importantly, the modified fern-like bismuth vanadate photocatalytic nanomaterial is used as a functional material and in situ grown on conductive glass, which can greatly improve the stability of the photoanode and the detection sensitivity of the corresponding sensor. Moreover, since the modified fern-like bismuth vanadate photocatalytic nanomaterial has the advantages of large specific surface area, multiple active sites, and good biocompatibility, it is more conducive to the stable modification of specific aptamer probes for identifying and capturing pollutants on the modified fern-like bismuth vanadate photocatalytic nanomaterial, and can shorten the diffusion distance of photogenerated carriers. At the same time, since the modified fern-like bismuth vanadate photocatalytic nanomaterial has high electrical conductivity and thermal stability, it is beneficial to improve the light energy utilization rate of the photoanode and promote the separation of photogenerated carriers, thereby greatly improving the sensitivity of the photoelectrochemical aptamer sensor, thereby making the photoelectrochemical aptamer have a wide detection range and low detection limit. Therefore, when the photoanode constructed by the present invention is used as the working electrode of the photoelectrochemical aptamer sensor, it can be directly used to detect environmental pollutants (such as bisphenol A), with the advantages of high stability, wide detection range, and low detection limit, which is of great significance for guiding the effective removal of pollutants in the environment.

[0033] (2) In view of the defects of the preparation method, such as harsh reaction conditions, high safety hazards, easy destruction of crystal structure, and the resulting poor photocatalytic activity and stability of bismuth vanadate nanomaterials, the present invention creatively provides a preparation method for a photoanode based on modified fern-like bismuth vanadate photocatalytic nanomaterials. First, a mixed solution is prepared using bismuth salt and vanadium salt as raw materials. Then, by adjusting the pH value of the mixed solution to 3-4 and adding conductive glass, a fern-like bismuth vanadate nanomaterial with a unique fern-like biomimetic morphology grown in situ on the surface of the conductive glass can be prepared through a simple hydrothermal treatment. Then, the fern-like bismuth vanadate nanomaterial is placed in a nitrogen atmosphere and heated to 350°C-650°C for calcination. Nitrogen doping can be introduced on the surface of the fern-like bismuth vanadate nanomaterial and oxygen defects can be generated. Not only are the reaction conditions mild, safe and reliable, but it is also easier to introduce oxygen defects into the surface of the material rather than deep (inside), thereby in situ growing the modified fern-like bismuth vanadate photocatalytic nanomaterial with excellent photocatalytic performance and good stability on the surface of the conductive glass. On this basis, the specific aptamer probe is modified on the modified fern-like bismuth vanadate photocatalytic nanomaterial on the surface of the conductive glass to obtain a photoanode based on the modified fern-like bismuth vanadate photocatalytic nanomaterial. Compared with the conventional preparation method, the preparation method of the present invention uses the modified fern-like bismuth vanadate nanomaterial with a unique fern-like biomimetic morphology as the functional material, which is more conducive to stably loading more specific aptamer probes on the surface of the photoanode. It can not only greatly shorten the modification steps of the electrode, making its preparation process simpler, but also be more conducive to improving the detection sensitivity of the photoelectric aptamer sensor, which has a natural advantage. At the same time, the preparation method of the present invention also has the advantages of simple process, easy operation, low cost, high yield, etc., is suitable for large-scale preparation, and is convenient for industrial use.

[0034] (3) In the preparation method of the present invention, by optimizing the calcination temperature, it is more conducive to introducing oxygen defects into the surface of the material, thereby effectively preventing oxygen defects from entering the interior of the crystal, thereby obtaining a modified fern-shaped bismuth vanadate photocatalytic nanomaterial with better photocatalytic performance and better stability. For example, compared with the calcination temperature of 350°C or 650°C, the fluorescence emission signal of the modified fern-shaped bismuth vanadate photocatalytic nanomaterial prepared at 400°C-600°C is weaker and the photocurrent signal is stronger, which shows that the modified fern-shaped bismuth vanadate photocatalytic nanomaterial prepared thereby has better photocatalytic performance. In particular, when the calcination temperature is lower than 350°C, it is difficult to successfully introduce the N element by calcining in an N2 atmosphere, and when it is higher than 650°C, body defects will be formed, which will serve as the recombination center of the photogenerated carrier and will lead to a decrease in the catalytic activity of the catalyst.

[0035] (4) The present invention also provides an application of a photoanode based on a modified fern-like bismuth vanadate photocatalytic nanomaterial in detecting pollutants in the environment, wherein the pollutant solution to be detected is dripped onto the surface of the photoanode for cultivation, so that the specific aptamer probe on the surface of the photoanode specifically identifies and captures the pollutant, thereby obtaining a photoanode with captured pollutants; the photoanode with captured pollutants is used as a working electrode, and a platinum electrode is used as a photocathode, and placed in a PBS buffer solution to construct a two-electrode photoelectrochemical aptamer sensor, which is connected to a power supply and subjected to an LSV test under light conditions to obtain the maximum power value of the pollutant solution to be detected; according to the maximum power value of the pollutant solution to be detected, a detection linear regression equation is constructed using the relationship between the concentration of the pollutant solution and the change in the maximum power value to calculate the concentration of the pollutant solution to be detected, thereby realizing the detection of the solution pollutants, which has the advantages of simple process, convenient operation, low cost, high stability, wide detection range, low detection limit, etc., and is of great significance for guiding the effective treatment of pollutants in the solution. Taking bisphenol A as an example, when the photoelectrochemical aptamer sensor constructed based on the photoanode of the modified fern-like bismuth vanadate photocatalytic nanomaterial of the present invention is used for detection, the detection range of bisphenol A is (0.1nM~100μM) and the detection lower limit is (0.025nM), which can quickly and accurately detect pollutants in different water bodies. At the same time, the photoelectrochemical aptamer sensor constructed using the present invention can also be reused multiple times, which not only has good reusability but also is more conducive to reducing processing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0037] Figure 1This is a SEM image of the FTO electrode sheet prepared in Example 1 of the present invention with modified fern-like bismuth vanadate photocatalytic nanomaterials grown in situ on the surface.

[0038] Figure 2 Figure 2 shows the PI curve and linear fitting diagram obtained by the photoelectrochemical aptamer sensor in Example 2 of the present invention for detecting bisphenol A at different concentrations, where aj represents the concentrations of the bisphenol A standard solution: a) 0.0001 μM; b) 0.001 μM; c) 0.01 μM; d) 0.5 μM; e) 0.1 μM; f) 1 μM; g) 10 μM; h) 20 μM; i) 50 μM; j) 100 μM.

[0039] Figure 3 The SEM images of the fern-like bismuth vanadate nanomaterial (a), modified fern-like bismuth vanadate photocatalytic nanomaterial (b) and sheet-like bismuth vanadate nanomaterial (c) prepared by the present invention, where a is "fern-like" BiVO4, b is N / O v / BiVO4-450, c is BiVO4 nanosheet.

[0040] Figure 4 The fern-like bismuth vanadate nanomaterial ("fern-like" BiVO4) and modified fern-like bismuth vanadate photocatalytic nanomaterial (N / O v / BiVO4-450) and sheet-like bismuth vanadate nanomaterials (BiVO4 nanosheets).

[0041] Figure 5 The fern-like bismuth vanadate nanomaterial ("fern-like" BiVO4) and modified fern-like bismuth vanadate photocatalytic nanomaterial (N / O v / BiVO4-350、N / O v / BiVO4-450、N / O v / BiVO4-550、N / O v / BiVO4-650) and sheet-like bismuth vanadate nanomaterials (BiVO4 nanosheets).

[0042] Figure 6 The fern-like bismuth vanadate nanomaterial ("fern-like" BiVO4) and modified fern-like bismuth vanadate photocatalytic nanomaterial (N / O v / BiVO4-350、N / O v / BiVO4-450、N / O v / BiVO4-550、N / O v / BiVO4-650) and sheet-like bismuth vanadate nanomaterials (BiVO4 nanosheets).

[0043] Figure 7The fern-like bismuth vanadate nanomaterial ("fern-like" BiVO4) and modified fern-like bismuth vanadate photocatalytic nanomaterial (N / O v / BiVO4-350、N / O v / BiVO4-450、N / O v / BiVO4-550、N / O v / BiVO4-650) and sheet-like bismuth vanadate nanomaterials (BiVO4 nanosheets).

[0044] Figure 8 The fern-like bismuth vanadate nanomaterial ("fern-like" BiVO4) and modified fern-like bismuth vanadate photocatalytic nanomaterial (N / O v / BiVO4-350、N / O v / BiVO4-450、N / O v / BiVO4-550、N / O v / BiVO4-650) XPS O1s spectrum.

[0045] Figure 9 The fern-like bismuth vanadate nanomaterial ("fern-like" BiVO4) and modified fern-like bismuth vanadate photocatalytic nanomaterial (N / O v / BiVO4-350、N / O v / BiVO4-450、N / O v / BiVO4-550、N / O v / BiVO4-650) XPS N1s spectrum. DETAILED DESCRIPTION

[0046] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but the scope of protection of the present invention is not limited thereby. The materials and instruments used in the following examples are all commercially available.

[0047] Example 1:

[0048] A photoanode based on modified fern-like bismuth vanadate photocatalytic nanomaterials comprises a conductive substrate, wherein the modified fern-like bismuth vanadate photocatalytic nanomaterials are in-situ grown on the surface of the conductive substrate, the modified fern-like bismuth vanadate photocatalytic nanomaterials comprise fern-like bismuth vanadate nanomaterials, nitrogen elements and oxygen defects are introduced on the surface of the fern-like bismuth vanadate nanomaterials, and the modified fern-like bismuth vanadate photocatalytic nanomaterials are modified with specific aptamer probes.

[0049] In this embodiment, the modified fern-shaped bismuth vanadate photocatalytic nanomaterial is prepared by calcining a fern-shaped bismuth vanadate nanomaterial under a nitrogen atmosphere, wherein the fern-shaped bismuth vanadate nanomaterial is obtained by hydrothermal treatment of bismuth salt and vanadium salt as raw materials at a pH value of 3 to 4.

[0050] In this embodiment, bismuth vanadate nanoparticles are distributed on the surface of the fern-shaped bismuth vanadate nanomaterial.

[0051] In this embodiment, the conductive substrate is a fluorine-doped tin dioxide transparent conductive glass electrode sheet.

[0052] In this embodiment, the DNA substrate chain of the specific aptamer probe has the nucleotide sequence shown in SEQ ID NO.1; the 5' end of the DNA substrate chain is labeled with a carboxyl group, specifically: 5'-COOH-CCG GTG GGT GGT CAG GTG GGA TAGCGT TCC GCG TAT GGC CCA GCG CAT CAC GGG TTC GCA CCA-3'.

[0053] The method for preparing the photoanode based on the modified fern-shaped bismuth vanadate photocatalytic nanomaterial in the above embodiment includes the following steps:

[0054] (1) Dissolve 60 mg of bismuth nitrate pentahydrate in 40 mL of deionized water, stir evenly, add 100 mg of sodium orthovanadate, and stir for 10 minutes to obtain a mixed solution A.

[0055] (2) adjusting the pH value of the mixed solution A obtained in step (1) to 4 with glacial acetic acid to obtain a mixed solution B.

[0056] (3) The mixed solution B obtained in step (2) was mixed with the FTO electrode sheet, transferred to the inner lining of the reactor, installed in the steel jacket of the hydrothermal reactor, and subjected to hydrothermal reaction at a temperature of 180° C. for 12 h. After the hydrothermal reaction was completed, the temperature was naturally cooled to room temperature, and vacuum dried at 45° C. for 6 h to obtain an FTO electrode sheet with fern-like bismuth vanadate nanomaterials in situ grown on the surface.

[0057] In this step, the FTO electrode sheet used is subjected to the following treatment before use: the FTO electrode with a thickness of 1.0 mm is cut into electrode sheets with a width of 20.0 mm and a length of 50.0 mm, and then the FTO electrode sheet cut into a predetermined size is placed in an acetone solution with a mass concentration of ≥99.0% for ultrasonic cleaning multiple times, and then the FTO electrode sheet is immersed in a hydrogen peroxide / sulfuric acid mixed solution for 80 seconds, blown dry under nitrogen to obtain a clean FTO electrode sheet after treatment, and dust-proofed for standby use, wherein the hydrogen peroxide / sulfuric acid mixed solution is a mixture of hydrogen peroxide solution and sulfuric acid solution, the volume ratio of hydrogen peroxide solution to sulfuric acid solution is 2:3, the mass concentration of hydrogen peroxide solution is 30%, and the mass concentration of sulfuric acid solution is 98%.

[0058] (4) The FTO electrode sheet with fern-like bismuth vanadate nanomaterials in situ grown on the surface obtained in step (3) is placed in a clean quartz crucible, and the temperature is raised to 450°C at a heating rate of 3°C / min under a nitrogen atmosphere and calcined for 3 hours. By calcination, nitrogen elements are introduced into the fern-like bismuth vanadate nanomaterials and oxygen vacancies are generated, thereby obtaining an FTO electrode sheet with modified fern-like bismuth vanadate photocatalytic nanomaterials in situ grown on the surface.

[0059] (5) The FTO electrode sheet with the modified fern-like bismuth vanadate photocatalytic nanomaterial in situ grown on the surface obtained in step (4) was immersed in a 3-aminopropyltriethoxysilane solution for 5 hours, removed with clean tweezers and naturally dried to obtain an amino-functionalized FTO electrode sheet. In this step, the 3-aminopropyltriethoxysilane solution was prepared by mixing 1 mL of 3-aminopropyltriethoxysilane (APTES) with 10 mL of ultrapure water.

[0060] (6) The specific nucleic acid aptamer solution is added dropwise to the amino-functionalized conductive glass surface obtained in step (1), and the solution is incubated at 4°C for 40 minutes to modify the specific nucleic acid aptamer on the modified fern-like bismuth vanadate photocatalytic nanomaterial. After the electrode surface is washed with a phosphate buffer solution, a photoanode based on the modified fern-like bismuth vanadate photocatalytic nanomaterial is obtained, which is placed in a 4°C refrigerator for later use.

[0061] In this step, the specific nucleic acid aptamer solution also undergoes the following treatment before use: 100 μL of a 3 μM carboxyl-modified bisphenol A specific nucleic acid aptamer solution (commercially available) is mixed with 30 μL of a solution containing N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and the mixture is activated at 37°C for 12 hours to obtain an activated specific nucleic acid aptamer solution. The concentration of N-hydroxysuccinimide in the solution containing N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is 2 M, and the concentration of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is 4 M. The carboxyl-modified bisphenol A-specific nucleic acid aptamer is 5'-COOH-CCG GTG GGTGGT CAG GTG GGA TAG CGT TCC GCG TAT GGC CCA GCG CAT CAC GGG TTC GCA CCA-3'.

[0062] Figure 1 This is a SEM image of the FTO electrode sheet with modified fern-like bismuth vanadate photocatalytic nanomaterials grown in situ on the surface prepared in Example 1 of the present invention. Figure 1 It can be seen that the modified fern-like bismuth vanadate photocatalytic nanomaterial grows vertically on the surface of the FTO electrode sheet, and the layer thickness is about 428.80 nm.

[0063] Example 2

[0064] An application of a photoanode based on a modified fern-shaped bismuth vanadate photocatalytic nanomaterial in detecting pollutants in the environment, specifically using the photoanode prepared in Example 1 to construct a photoelectric aptamer sensor and use it to detect the concentration of bisphenol A in a solution, comprising the following steps:

[0065] (a) Bisphenol A solutions of different concentrations were added dropwise to the surface of the photoanode and incubated at 37°C for 30 min. This allowed the specific aptamer probe on the photoanode to specifically recognize and capture bisphenol A, resulting in a photoanode with captured bisphenol A.

[0066] (b) The photoanode containing bisphenol A obtained in step (a) was used as a working electrode, and a platinum electrode was used as a photocathode, and placed in a PBS buffer solution to construct a two-electrode photoelectrochemical aptamer sensor. The sensor was connected to a power supply and subjected to an LSV test under illumination to obtain the maximum power values of bisphenol A solutions with different concentrations.

[0067] (c) Based on the different maximum power values of bisphenol A solutions with different concentrations, a linear regression equation is drawn to detect the relationship between the change in bisphenol A solution concentration and the maximum power value.

[0068] (d) According to the operations of steps (a) and (b), the maximum power of the bisphenol A solution to be tested is detected, and the concentration of the pollutant solution to be tested is calculated using the detection linear regression equation drawn in step (c).

[0069] Figure 2 The PI curve and linear fitting diagram of the photoelectrochemical aptamer sensor in Example 2 of the present invention for detecting different concentrations of bisphenol A, aj respectively represent the concentrations of bisphenol A standard solution: a) 0.0001μM; b) 0.001μM; c) 0.01μM; d) 0.5μM; e) 0.1μM; f) 1μM; g) 10μM; h) 20μM; i) 50μM; j) 100μM. Figure 2 A can be seen that its maximum power value (P max ) increases with the increase of bisphenol A concentration. Figure 2 B shows that the linear regression equation for the relationship between different concentrations of bisphenol A solution and the maximum power value is as shown in formula (1):

[0070] P max =0.5527×lgC 双酚A +2.253 (1),

[0071] In formula (1), P max is the maximum power value, C 双酚A is the concentration of bisphenol A in the solution, in μM, R2 =0.9922, the linear detection range is 0.1nM~100μM, and the detection limit is 0.025nM.

[0072] It can be seen that the photoelectrochemical aptamer sensor in Example 2 can be used to detect bisphenol A, and the P measured according to the PI curve max The value is used to determine the concentration of bisphenol A in relevant application cases.

[0073] Example 3

[0074] Inspection N / O v / BiVO4 as a functional nanomaterial for detecting environmental pollutants, specifically to investigate the surface growth of N / O v The detection accuracy of the photoelectrochemical aptamer sensor prepared by using FTO electrode sheets of / BiVO4 "fern-like" nanomaterials as photoanode.

[0075] In order to further verify the detection effect of the photoelectrochemical aptamer sensor in Example 2 in actual applications, the photoelectrochemical aptamer sensor was used for target detection in actual samples (the determination method refers to Example 2), and a recovery experiment was performed.

[0076] The photoelectrochemical aptamer sensor described in Example 2 was used to detect the concentration of bisphenol A in laboratory water, lake water, and sewage samples. Specifically, the laboratory water, lake water, and sewage samples were pretreated by filtration, and the supernatant was adjusted to a pH of 7.4 using phosphate buffer solution. The target substance concentrations in the samples are shown in Table 1. The photoelectrochemical aptamer sensor described in Example 2 was then used to detect the concentration of bisphenol A in the test solution according to the method described in Example 2. The results were compared with those obtained by conventional high-performance liquid chromatography (HPLC). The results are shown in Table 1.

[0077] Table 1 Recovery verification results of the test solution

[0078]

[0079]

[0080] a Rec: recovery rate. b Below the detection limit

[0081] As can be seen from the table, the photoelectrochemical aptamer sensor of the present invention has a recovery rate of approximately 95.00% to 109.00% within the measurable concentration range, demonstrating ideal test results. Compared to traditional detection technologies, the detection method using the photoelectrochemical aptamer sensor of the present invention is simple and rapid to operate.

[0082] As can be seen from Table 1, the photoelectrochemical aptasensor of the present invention can be used to detect bisphenol A in water and can achieve good detection accuracy.

[0083] In the present invention, the effects of different calcination temperatures on the properties of fern-like bismuth vanadate nanomaterials were also investigated. The modified fern-like bismuth vanadate photocatalytic nanomaterials obtained by calcining at 350°C, 450°C, 550°C, and 650°C were respectively denoted as N / O v / BiVO4-350、N / O v / BiVO4-450、N / O v / BiVO4-550、N / O v / BiVO4-650.

[0084] Among them, the modified fern-like bismuth vanadate photocatalytic nanomaterials (N / O v / BiVO4-450) preparation method, comprising the following steps:

[0085] (1) Dissolve 60 mg of bismuth nitrate pentahydrate in 40 mL of deionized water, stir evenly, add 100 mg of sodium orthovanadate, and stir for 10 minutes to obtain a mixed solution A.

[0086] (2) adjusting the pH value of the mixed solution A obtained in step (1) to 4 with glacial acetic acid to obtain a mixed solution B.

[0087] (3) The mixed solution B obtained in step (3) was transferred to the lining of the reactor, installed in the steel jacket of the hydrothermal reactor, and subjected to hydrothermal reaction at a temperature of 180° C. for 12 h. After the hydrothermal reaction was completed, it was naturally cooled to room temperature and vacuum dried at 45° C. for 6 h to obtain a fern-like bismuth vanadate nanomaterial, which was recorded as "fern-like" BiVO4.

[0088] (4) The fern-shaped bismuth vanadate nanomaterial obtained in step (d) was placed in a clean quartz crucible, and the temperature was raised to 450°C at a heating rate of 3°C / min under a nitrogen atmosphere and calcined for 3 h. By calcining, nitrogen elements were introduced into the fern-shaped bismuth vanadate nanomaterial and oxygen vacancies were generated, thereby obtaining a modified fern-shaped bismuth vanadate photocatalytic nanomaterial, which was recorded as N / O v / BiVO4-450.

[0089] In the present invention, the effect of different pH values on the performance of fern-like bismuth vanadate nanomaterials is also investigated, wherein the preparation method of the flake-like bismuth vanadate nanomaterial comprises the following steps:

[0090] (1) Dissolve 60 mg of bismuth nitrate pentahydrate in 40 mL of deionized water, stir evenly, add 100 mg of sodium orthovanadate, and stir for 10 minutes to obtain a mixed solution A.

[0091] (2) The pH value of the mixed solution A obtained in step (1) is adjusted to 6 with glacial acetic acid to obtain a mixed solution B.

[0092] (3) The mixed solution B obtained in step (3) was transferred to the lining of the reactor, installed in the steel jacket of the hydrothermal reactor, and subjected to hydrothermal reaction at a temperature of 180° C. for 12 h. After the hydrothermal reaction was completed, the temperature was naturally cooled to room temperature and vacuum dried at 45° C. for 6 h to obtain sheet-like bismuth vanadate nanomaterials, which were recorded as BiVO4 nanosheets.

[0093] The prepared fern-like bismuth vanadate nanomaterials ("fern-like" BiVO4) and modified fern-like bismuth vanadate photocatalytic nanomaterials (N / O v / BiVO4-450) and sheet-like bismuth vanadate nanomaterials (BiVO4 nanosheets) were subjected to SEM analysis. The results are shown in Figure 3 shown. Figure 3 The SEM images of the fern-like bismuth vanadate nanomaterial (a), modified fern-like bismuth vanadate photocatalytic nanomaterial (b) and sheet-like bismuth vanadate nanomaterial (c) prepared by the present invention, where a is "fern-like" BiVO4, b is N / O v / BiVO4-450, c is BiVO4 nanosheet. Figure 3 a, 3b show that the “fern-like” BiVO4 and N / O v / BiVO4-450 both show a fern-like morphology with a size of 500nm, and particles with a diameter of 10nm are evenly distributed on the surface. This unique biomimetic morphology structure will bring a larger specific surface area. Figure 3 a, 3b show that the “fern-like” BiVO4 and N / O v / BiVO4-450 has almost the same morphology, indicating that calcination in nitrogen atmosphere will not destroy the special morphology of BiVO4. Figure 3 c It can be seen that the BiVO4 nanosheets exhibit a typical sheet-like structure and a smooth surface.

[0094] The prepared fern-like bismuth vanadate nanomaterials ("fern-like" BiVO4) and modified fern-like bismuth vanadate photocatalytic nanomaterials (N / O v / BiVO4-450) and sheet-like bismuth vanadate nanomaterials (BiVO4 nanosheets) were tested for nitrogen adsorption and desorption, and the results were as follows. Figure 4 shown. Figure 4 The fern-like bismuth vanadate nanomaterial ("fern-like" BiVO4) and modified fern-like bismuth vanadate photocatalytic nanomaterial (N / O v / BiVO4-450) and flake bismuth vanadate nanomaterials (BiVO4 nanosheets). After BET calculation, the nitrogen adsorption-desorption isotherm of the “fern-like” BiVO4 is 18.65m 2 / g,N / Ov / BiVO4-450 is 20.59m 2 / g, BiVO4 nanosheets are 8.22m 2 / g. It can be seen that compared with BiVO4 nanosheets, N / O v Both / BiVO4-450 and "fern-shaped" BiVO4 have large specific surface areas, which are beneficial to increasing the contact area between the catalyst and environmental pollutants and increasing the reaction sites.

[0095] The prepared fern-like bismuth vanadate nanomaterials ("fern-like" BiVO4) and modified fern-like bismuth vanadate photocatalytic nanomaterials (N / O v / BiVO4-350、N / O v / BiVO4-450、N / O v / BiVO4-550、N / O v / BiVO4-650) and sheet-like bismuth vanadate nanomaterials (BiVO4 nanosheets) were subjected to UV-diffuse spectral reflectance analysis, and the results are as follows Figure 5 shown. Figure 5 The fern-like bismuth vanadate nanomaterial ("fern-like" BiVO4) and modified fern-like bismuth vanadate photocatalytic nanomaterial (N / O v / BiVO4-350、N / O v / BiVO4-450、N / O v / BiVO4-550、N / O v / BiVO4-650) and sheet-like bismuth vanadate nanomaterials (BiVO4 nanosheets). Figure 5 It can be seen that the light absorption ability of "fern-like" BiVO4 is improved to a certain extent compared with BiVO4 nanosheets; the modified fern-like bismuth vanadate photocatalytic nanomaterials (N / O v / BiVO4-350、N / O v / BiVO4-450、N / O v / BiVO4-550、N / O v / BiVO4-650) has a certain red shift in visible light absorption edge compared with the pure "fern-like" BiVO4, and with the increase of calcination temperature, the N / O v / BiVO4-x has a slightly enhanced absorption. This shows that the "fern-like" BiVO4 has better light absorption ability than the lamellar BiVO4. At the same time, the introduction of nitrogen and oxygen defects can further improve the light response range of the "fern-like" BiVO4, thereby further improving the light energy utilization rate of the material.

[0096] The prepared fern-like bismuth vanadate nanomaterials ("fern-like" BiVO4) and modified fern-like bismuth vanadate photocatalytic nanomaterials (N / O v / BiVO4-350、N / O v / BiVO4-450、N / O v / BiVO4-550、N / O v / BiVO4-650) and sheet-like bismuth vanadate nanomaterials (BiVO4 nanosheets) were subjected to photoluminescence fluorescence spectrum analysis and photocurrent response signal analysis. The results are as follows Figure 6 、 7 shown. Figure 6 The fern-like bismuth vanadate nanomaterial ("fern-like" BiVO4) and modified fern-like bismuth vanadate photocatalytic nanomaterial (N / O v / BiVO4-350、N / O v / BiVO4-450、N / O v / BiVO4-550、N / O v / BiVO4-650) and sheet-like bismuth vanadate nanomaterials (BiVO4 nanosheets). Figure 7 The fern-like bismuth vanadate nanomaterial ("fern-like" BiVO4) and modified fern-like bismuth vanadate photocatalytic nanomaterial (N / O v / BiVO4-350、N / O v / BiVO4-450、N / O v / BiVO4-550、N / O v / BiVO4-650) and flake bismuth vanadate nanomaterials (BiVO4 nanosheets). Fluorescence is caused by the recombination of photogenerated carriers and can reflect the separation, transfer and migration of carriers. Fern-like bismuth vanadate nanomaterials ("fern-like" BiVO4), modified fern-like bismuth vanadate photocatalytic nanomaterials (N / O v / BiVO4-350、N / O v / BiVO4-450、N / O v / BiVO4-550、N / O v / BiVO4-650) and the steady-state fluorescence emission spectra (λ ex 365nm), such as Figure 6 As shown in the figure, the fluorescence intensity of BiVO4 nanosheets is significantly higher than that of "fern-like" BiVO4, indicating that the carrier loading rate of the former is much higher than that of the latter. v / BiVO4-350、N / O v / BiVO4-450、N / Ov / BiVO4-550、N / O v / BiVO4-650) is lower than that of the “fern-like” BiVO4, and shows a trend of first decreasing and then increasing with the increase of calcination temperature, indicating that the recombination of photoelectron-hole pairs first decreases and then increases. Figure 7 The photocurrent response signal shown in also has the same characteristics, N / O v / BiVO4-450 has a stronger photocurrent signal than N / O v / BiVO4-550 and N / O v / BiVO4-650. It can be seen that the N doping degree of the modified fern-like bismuth vanadate photocatalytic nanomaterials deepens with the increase of calcination temperature, resulting in more bulk oxygen defects. When the bulk oxygen defects increase, they serve as the recombination center of the photogenerated carriers, which will also lead to a decrease in the catalytic activity of the catalyst. Therefore, relatively speaking, calcination at 400℃-600℃ is more conducive to the introduction of surface oxygen defects on the surface of the material. The surface oxygen defects can serve as carrier traps and adsorption sites for active substances, thereby more effectively suppressing the recombination of photogenerated electrons and holes, which is consistent with the Figure 6 、 7 The results are consistent with those in , that is, the fluorescence emission signal becomes weaker and the photocurrent signal is enhanced. In particular, when the calcination temperature is 450 ° C, the prepared modified fern-like bismuth vanadate photocatalytic nanomaterial has a more appropriate oxygen defect surface and exhibits very excellent photocatalytic performance.

[0097] The fern-like bismuth vanadate nanomaterials ("fern-like" BiVO4) and modified fern-like bismuth vanadate photocatalytic nanomaterials (N / O v / BiVO4-350、N / O v / BiVO4-450、N / O v / BiVO4-550、N / O v XPS analysis was performed on the bismuth vanadate nanomaterials (BiVO4 nanosheets) prepared in Example 1 and the comparative example 1. Figure 8 、 9 shown.

[0098] Figure 8 The fern-like bismuth vanadate nanomaterial ("fern-like" BiVO4) and modified fern-like bismuth vanadate photocatalytic nanomaterial (N / O v / BiVO4-350、N / O v / BiVO4-450、N / O v / BiVO4-550、N / O v / BiVO4-650) XPS O1s spectrum. Figure 8 The characteristic peaks of O1s can be divided into OL ,O V and O A Three types, representing lattice oxygen (O L ), oxygen vacancy area (O v ), and oxygen chemically absorbed from water (O A ).Depend on Figure 8 As shown in Table 2, with the increase of calcination temperature, the peak area of Ov increases continuously, which indicates the increase of defective oxygen.

[0099] Table 2 Photocatalytic properties of fern-like bismuth vanadate nanomaterials (“fern-like” BiVO4) and modified fern-like bismuth vanadate nanomaterials

[0100] (N / O v / BiVO4-350、N / O v / BiVO4-450、N / O v / BiVO4-550、N / O v / BiVO4-650) high-resolution XPS peaks calculated from the O L , O v and O c Peak area

[0101] Material <![CDATA[O L Peak area]]> <![CDATA[O v Peak area]]> <![CDATA[O c Peak area]]> <![CDATA["Fern-like" BiVO4]]> 76862.87 28943.01 16233.10 <![CDATA[N / O v / BiVO4-350]]> 92752.95 51017.38 10972.29 <![CDATA[N / O v / BiVO4-450]]> 100624.56 63616.71 13644.37 <![CDATA[N / O v / BiVO4-550]]> 110109.44 70961.91 16050.75 <![CDATA[N / O v / BiVO4-650]]> 102826.42 71074.12 4967.27

[0102] Figure 9 The fern-like bismuth vanadate nanomaterial ("fern-like" BiVO4) and modified fern-like bismuth vanadate photocatalytic nanomaterial (N / O v / BiVO4-350、N / O v / BiVO4-450、N / O v / BiVO4-550、N / O v / BiVO4-650) XPS N1s spectrum. Figure 9 As shown in Table 3, with the increase of calcination temperature, the nitrogen content on the surface of the modified fern-like bismuth vanadate photocatalytic nanomaterials also increases.

[0103] Table 3 Photocatalytic properties of fern-like bismuth vanadate nanomaterials ("fern-like" BiVO4) and modified fern-like bismuth vanadate nanomaterials

[0104] (N / O v / BiVO4-350、N / O v / BiVO4-450、N / O v / BiVO4-550、N / O v The peak area of the nitrogen characteristic peak calculated by high-resolution XPS peak of BiVO4-650

[0105] Material Characteristic peak area <![CDATA[N / O v / BiVO4-350]]> 2159.16 <![CDATA[N / O v / BiVO4-450]]> 2599.83 <![CDATA[N / O v / BiVO4-550]]> 3355.31 <![CDATA[N / O v / BiVO4-650]]> 3414.60

[0106] In summary, the modified fern-shaped bismuth vanadate photocatalytic nanomaterial of the present invention has the advantages of large specific surface area, multiple active sites, strong light absorption ability, wide light response range, low photogenerated electron-hole recombination rate, good conductivity, high photocatalytic activity, good stability, etc. It is a new type of bismuth vanadate catalyst that can be widely used and has excellent performance. The modified fern-shaped bismuth vanadate photocatalytic nanomaterial is used as a functional material and is grown in situ on conductive glass, which can greatly improve the stability of the photoanode and the detection sensitivity of the corresponding sensor. Moreover, since the modified fern-shaped bismuth vanadate photocatalytic nanomaterial has the advantages of large specific surface area, multiple active sites, and good biocompatibility, it is more conducive to the stable modification of specific aptamer probes for identifying and capturing pollutants. In the modified fern-like bismuth vanadate photocatalytic nanomaterial, the diffusion distance of photogenerated carriers can be shortened. At the same time, since the modified fern-like bismuth vanadate photocatalytic nanomaterial has high electrical conductivity and thermal stability, it is beneficial to improve the light energy utilization rate of the photoanode and promote the separation of photogenerated carriers, thereby greatly improving the sensitivity of the photoelectrochemical aptamer, and thus making the photoelectrochemical aptamer have a wide detection range and a low detection limit. Therefore, when the photoanode constructed by the above-mentioned present invention is used as the working electrode of the photoelectrochemical aptamer sensor, it can be directly used to detect environmental pollutants (such as bisphenol A), and has the advantages of high stability, wide detection range, and low detection limit, which is of great significance for guiding the effective removal of pollutants in the environment.

[0107] The above description is only a preferred embodiment of the present invention and does not constitute any formal limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the spirit and technical solution of the present invention, use the methods and technical contents disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention, still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A photoanode based on modified fern-shaped bismuth vanadate photocatalytic nanomaterials, characterized in that: The invention comprises a conductive substrate, wherein a modified fern-like bismuth vanadate photocatalytic nanomaterial is in situ grown on the surface of the conductive substrate, wherein the modified fern-like bismuth vanadate photocatalytic nanomaterial comprises a fern-like bismuth vanadate nanomaterial, wherein nitrogen elements and oxygen defects are introduced on the surface of the fern-like bismuth vanadate nanomaterial; bismuth vanadate nanoparticles are distributed on the surface of the fern-like bismuth vanadate nanomaterial; and the modified fern-like bismuth vanadate photocatalytic nanomaterial is modified with a specific aptamer probe; The modified fern-shaped bismuth vanadate photocatalytic nanomaterial is prepared by calcining a fern-shaped bismuth vanadate nanomaterial under a nitrogen atmosphere; the calcination temperature is 400°C to 600°C; the fern-shaped bismuth vanadate nanomaterial is prepared by hydrothermal treatment of bismuth salt and vanadium salt as raw materials at a pH value of 3 to 4; the bismuth salt is bismuth nitrate pentahydrate; and the vanadium salt is sodium orthovanadate.

2. The photoanode based on the modified fern-shaped bismuth vanadate photocatalytic nanomaterial according to claim 1, characterized in that: The conductive substrate is a fluorine-doped tin dioxide transparent conductive glass electrode; the DNA substrate chain of the specific aptamer probe has a nucleotide sequence shown in SEQ ID NO.1; and the 5' end of the DNA substrate chain is labeled with a carboxyl group.

3. A method for preparing a photoanode based on a modified fern-shaped bismuth vanadate photocatalytic nanomaterial according to claim 1 or 2, characterized in that: The following steps are involved: S1. Dissolve a bismuth salt in water, add a vanadium salt, and stir to obtain a mixed solution; S2. Adjusting the pH value of the mixed solution to 3-4, adding a conductive substrate, and performing a hydrothermal reaction to obtain a conductive substrate with fern-like bismuth vanadate nanomaterials in situ grown on the surface; S3. Under a nitrogen atmosphere, heating the conductive substrate with the fern-like bismuth vanadate nanomaterial in situ grown on the surface obtained in step S2 to 400° C. to 600° C. and calcining the substrate to obtain a conductive glass with the modified fern-like bismuth vanadate photocatalytic nanomaterial in situ grown on the surface; S4. Modify the specific aptamer probe on the modified fern-like bismuth vanadate photocatalytic nanomaterial on the surface of the conductive glass to obtain a photoanode based on the modified fern-like bismuth vanadate photocatalytic nanomaterial.

4. The preparation method according to claim 3, wherein In step S1, the mass fraction of the bismuth salt in the mixed solution is 1.25 mg / mL to 1.5 mg / mL, and the mass fraction of the vanadium salt is 1.5 mg / mL to 2.5 mg / mL; the stirring time is 5 min to 10 min; In step S2, glacial acetic acid is used to adjust the pH value of the mixed solution; the conductive substrate further includes the following treatment before use: placing the conductive glass in an acetone solution for ultrasonic cleaning, and immersing it in a mixed solution of hydrogen peroxide / sulfuric acid for 60 seconds to 100 seconds; the mass concentration of the acetone solution is ≥99.0%; the mixed solution of hydrogen peroxide / sulfuric acid is obtained by mixing a hydrogen peroxide solution and a sulfuric acid solution; the volume ratio of the hydrogen peroxide solution to the sulfuric acid solution is 1 to 2:3; the mass concentration of the hydrogen peroxide solution is 30%; the mass concentration of the sulfuric acid solution is 98%; the thickness of the conductive substrate is 1.0 mm to 1.5 mm, the width is 15.0 mm to 20.0 mm, and the length is 45.0 mm to 50.0 mm; the temperature of the hydrothermal reaction is 180° C. to 200° C.; the hydrothermal reaction time is 10 hours to 12 hours; after the hydrothermal reaction is completed, the product is dried under vacuum conditions; the drying temperature is 45° C.; and the drying time is 5 hours to 8 hours. In step S3, the calcination time is 2 h to 3 h.

5. The preparation method according to claim 3 or 4, characterized in that Step S4 includes the following steps: (1) immersing the conductive glass obtained in step S3, on which the modified fern-like bismuth vanadate photocatalytic nanomaterial is in situ grown, in a 3-aminopropyltriethoxysilane solution to obtain amino-functionalized conductive glass; (2) The specific nucleic acid aptamer solution is added dropwise to the amino-functionalized conductive glass surface obtained in step (1) for incubation, so that the specific nucleic acid aptamer is modified on the modified fern-like bismuth vanadate photocatalytic nanomaterial to obtain a photoanode based on the modified fern-like bismuth vanadate photocatalytic nanomaterial.

6. The preparation method according to claim 5, wherein In step (1), the 3-aminopropyltriethoxysilane solution is prepared by mixing 3-aminopropyltriethoxysilane with water; the volume ratio of the 3-aminopropyltriethoxysilane to water is 1:5 to 1:10; and the soaking time is 5 h to 10 h; In step (2), the specific nucleic acid aptamer solution further includes the following treatment before use: the specific nucleic acid aptamer solution is mixed with a solution containing N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride for activation to obtain an activated specific nucleic acid aptamer solution; the volume ratio of the specific nucleic acid aptamer solution to the solution containing N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is 5:2 to 5:1; the concentration of the specific nucleic acid aptamer solution is 3 μM; the concentration of N-hydroxysuccinimide in the solution containing N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is 1 M to 4 M, and the concentration of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is 2 M to 6 M; the activation is carried out at a temperature of 37°C; the activation time is 10 h~12h; the incubation is carried out at a temperature of 4°C; the incubation time is 40 min.

7. Use of a photoanode based on a modified fern-like bismuth vanadate photocatalytic nanomaterial as claimed in claim 1 or 2, or a photoanode based on a modified fern-like bismuth vanadate photocatalytic nanomaterial prepared by the preparation method according to any one of claims 3 to 6 in detecting pollutants in the environment.

8. The use according to claim 7, characterized in that The application comprises the following steps: (a) A solution of the pollutant to be detected is added dropwise to the surface of the photoanode for incubation, so that the specific aptamer probe on the surface of the photoanode specifically recognizes and captures the pollutant, thereby obtaining a photoanode with captured pollutants; (b) The pollutant-captured photoanode obtained in step (a) was used as a working electrode, and a platinum electrode was used as a photocathode in a PBS buffer solution to construct a two-electrode photoelectrochemical aptasensor. The sensor was connected to a power supply and subjected to an LSV test under illumination to obtain the maximum power value of the pollutant solution to be tested. (c) Based on the maximum power value of the pollutant solution to be tested obtained in step (b), the concentration of the pollutant solution to be tested is calculated using a detection linear regression equation constructed based on the relationship between the concentration of the pollutant solution and the change in the maximum power value.

9. The use according to claim 8, characterized in that In step (a), the incubation is carried out at a temperature of 4° C. and for 30 minutes. When the pollutant in the pollutant solution to be detected is bisphenol A, the DNA substrate strand of the specific aptamer probe used has a nucleotide sequence shown in SEQ ID NO. 1; the 5′ end of the DNA substrate strand is labeled with a carboxyl group. In step (c), when the pollutant in the pollutant solution to be tested is bisphenol A, the corresponding detection linear regression equation is: P max =0.5527×lgC 双酚A +2.253(1), In formula (1), P max is the maximum power value, C 双酚A is the concentration of bisphenol A in the solution, in μM, R 2 =0.9922, the linear detection range is 0.1 nM to 100 μM, and the detection limit is 0.025 nM.

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