CN115078499A - Preparation method of photoelectrochemical sensor for detecting microcystin LR - Google Patents

Abstract

The invention relates to a preparation method of a photoelectrochemical sensor for detecting microcystin LR, and is applied to the detection of microcystin LR in lake water. _The present invention adopts _Ti3C2Tx loaded _TiO2 nanometer array as photosensitive base material, _TiO2 has stable performance and low price, _{while Ti3C2Tx has properties} similar to metal, and has excellent conductivity and strong The surface plasmon resonance of _TiO2 can effectively improve the electron-hole recombination of TiO2 and enhance its visible light response. The material composite scheme adopted in the present invention retains the microstructure of the TiO ₂ nano-array, so that it can be used as a good sensing carrier to ensure the stability of signal output, and gold nano-ions are introduced through ion beam sputtering to fix the aptamer. It provides more active sites, and the microcystin LR acts as a natural electron donor to realize the sensing conversion from its own concentration to visual photocurrent signal.

Description

A kind of preparation method of photoelectrochemical sensor for detecting microcystin LR

technical field

The invention relates to a preparation method of a photoelectrochemical sensor for detecting microcystin LR, in particular using TiO ₂ /Ti ₃ C ₂ T _x as a base material to prepare a label-free photoelectrochemical sensor for detecting microcystin LR The sensor belongs to the technical field of novel functional materials and biological sensing detection.

Background technique

Titanium dioxide (TiO ₂ ) has attracted wide attention in photocatalysis and photoelectrochemical sensing due to its non-toxic, cheap and stable advantages, but its defects are also obvious. Ultraviolet light has an obvious response, while the absorption result of visible light is unsatisfactory, and its electron-hole recombination rate is relatively fast, which limits its application in different fields. For the modification of _TiO2 , methods such as quantum dot/dye sensitization, noble metal loading, ion doping, and construction of heterojunctions are widely used.

MXenes based on 2D transition metal carbides/nitrides are a new class of 2D functional materials with continuously tunable electronic structures from metallic to semiconducting and rich surface chemistry, which are widely used in energy storage, catalysis, environment, biological , electronics, electromagnetic shielding, superconductivity, sensing, separation technology, superconductivity and many other fields show a wide range of application prospects, and its diverse chemical composition and crystal structure provide a broad space for the regulation of its physical and chemical properties and service functions. . Ti ₃ C ₂ T _x is the most common MXene material. Compared with noble metal nanoparticles, it has a metal-like but 4-5 orders of magnitude lower intrinsic carrier concentration and a larger two-dimensional light absorption cross section. It has a significant surface plasmon resonance effect in the visible light region, and has great potential in the accumulation of visible light energy to improve the visible light absorption of broadband semiconductors.

The invention combines TiO ₂ with Ti ₃ C ₂ T _x , utilizes the ultra-high conductivity of Ti ₃ C ₂ T _x to realize the rapid transfer of photogenerated electrons in TiO ₂ , and benefits from the surface plasmon of Ti ₃ C ₂ T _x Resonance effect, realize the aggregation of visible light energy in the two, thereby improving the visible light utilization rate of TiO ₂ , and in the detection of microcystin LR in lake water using TiO ₂ /Ti ₃ C ₂ T _x as the photoelectric generator showed satisfactory results.

SUMMARY OF THE INVENTION

One of the purposes of the invention is to use TiO ₂ /Ti ₃ C ₂ T _x as the base material to generate photoelectric response. As a metal-like sensitizer, Ti ₃ C ₂ T _x can effectively improve the visible light response of TiO ₂ through surface plasmon resonance, providing a photocurrent basis for subsequent tests.

The second purpose of the present invention is to control the microscopic morphology of the TiO ₂ /Ti ₃ C ₂ T _x nano-array, and the final product preserves the microscopic morphology of TiO ₂ , which facilitates the transfer of electrons along the nanorods oriented with sufficient density and ensures the sensor’s performance. Batch-to-batch stability.

The third purpose of the present invention is that the proposed photoelectrochemical sensor is a signal-rising type, that is, the photocurrent will increase with the increase of the target concentration. The reason is that the microcystin LR itself is an electron donor, and this power supply The scheme replaces the traditional label-free photoelectric sensor that relies on electrode surface steric hindrance to realize signal change, and has higher sensitivity.

The technical scheme of the present invention is as follows:

1. a preparation method for detecting the photoelectrochemical sensor of Microcystin LR, the steps are as follows:

(1) Preparation of TiO ₂ nanoarrays: Spread the FTO glass with the conductive side up on the bottom of the hydrothermal reactor, and pour a mixture containing 8-45 mL deionized water, 8-45 mL concentrated hydrochloric acid and 0.2-1.2 mL titanic acid The mixed solution of tetrabutyl ester is incubated at 120-160 ^o C for 8-12 h to obtain _TiO nanoarrays, washed with deionized water for several times and dried;

(2) Preparation of single-layer Ti ₃ C ₂ T _x nanosheets: Disperse 0.1–0.5 g of accordion-shaped Ti ₃ C ₂ T _x in 15–25 mL of dimethyl sulfoxide, stir well at room temperature for 18–36 h cracked its accordion structure to obtain monolayer Ti ₃ C ₂ T _x nanosheets, then centrifuged the above mixture at 4000-6000 rpm for 20-40 min, and washed the pellet with deionized water several times to remove all DMSO , and finally monolayer Ti ₃ C ₂ T _x nanosheets were obtained;

(3) Preparation of TiO ₂ /Ti ₃ C ₂ T _x nanoarrays: The single-layer Ti ₃ C ₂ T _x nanosheets were re-dispersed in a three-necked flask filled with 20–100 mL of deionized water, and discharged by bubbling argon. Clean the air, and then ultrasonicate in an ice-water bath for 4 to 18 hours. The obtained product was allowed to stand for 8 to 12 hours, and then the upper layer of colloid was taken; in a plastic petri dish that was evacuated with argon, 50 to 200 μL of the upper layer of colloid was drop-coated on TiO ₂ nanoarrays, naturally volatilized at room temperature for 12 to 24 h, and calcined at 200 to 300 ^o C for 2 to 3 h in an argon atmosphere to obtain TiO ₂ /Ti ₃ C ₂ T _x nanoarrays, and the final product was low temperature in an argon atmosphere. store;

(4) Preparation of photoelectrochemical sensors: Sputtering a layer of gold nanoparticles on the surface of TiO ₂ /Ti ₃ C ₂ T _x nanoarrays using an ion beam sputtering instrument, adjusting the current of the sputtering instrument to 10 ~ 30 µA, and the sputtering time 30 ~ 80 s to obtain TiO ₂ /Ti ₃ C ₂ T _x /Au; take 6 µL, 20 ~ 100 µmol/L of the aptamer solution with thiol modified at the 3' end dropwise added to TiO ₂ /Ti ₃ C ₂ T _x /Au surface, dry naturally at room temperature; drop 3 µL of 1% 6-mercaptohexan-1-ol solution on the surface of the modified electrode; continue to drop 6 µL of standard microcapsules with different concentrations Cytotoxin LR completes sensor construction.

2. A photoelectrochemical sensor for detecting Microcystin LR, the detection step is as follows:

(1) The electrochemical workstation was used for testing with a three-electrode system, the Ag/AgCl electrode was used as the reference electrode, the platinum wire electrode was used as the counter electrode, and the prepared sensor was used as the working electrode. carry out testing;

(2) Microcystin LR was detected by time-amperometric method, the running time was 120 s, and the light source wavelength was 450 nm;

(3) After the electrodes are placed, turn on the light for 12 s every 12 s, record the photocurrent, and draw the working curve;

(4) Replace the standard microcystin LR standard solution with the lake water sample solution to be tested for detection.

specific embodiment

In order to further understand the present invention, the preferred embodiments of the present invention are described below with reference to examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

Example 1

(1) Preparation of TiO ₂ nanoarrays: Spread the FTO glass conductive side up on the bottom of the hydrothermal reactor, pour a mixture containing 8 mL of deionized water, 8 mL of concentrated hydrochloric acid and 0.2 mL of tetrabutyl titanate, Incubate at 120 ^o C for 8 h to obtain _TiO nanoarrays, wash with deionized water several times and dry;

(2) Preparation of single-layer Ti ₃ C ₂ T _x nanosheets: Disperse 0.1 g of accordion-shaped Ti ₃ C ₂ T _x in 15 mL of dimethyl sulfoxide, stir well at room temperature for 18 h to crack the accordion structure Monolayer Ti ₃ C ₂ T _x nanosheets were obtained, then the above mixture was centrifuged at 4000 rpm for 20 min, and the precipitate was washed several times with deionized water to remove all dimethyl sulfoxide, and finally mono layer Ti ₃ C ₂ T was obtained _x nanosheets;

(3) Preparation of TiO ₂ /Ti ₃ C ₂ T _x nanoarrays: The single-layer Ti ₃ C ₂ T _x nanosheets were re-dispersed in a three-necked flask filled with 20 mL of deionized water, and purged with argon. air, followed by sonication in an ice-water bath for 4 h, the obtained product was allowed to stand for 8 h, and then the upper layer of colloid was taken; in a plastic petri dish evacuated with argon, 50 μL of the upper layer of colloid was drop-coated on the _TiO2 nanoarray, at room temperature Naturally volatilized for 12 h, calcined at 200 ^o C for 2 h under argon atmosphere to obtain TiO ₂ /Ti ₃ C ₂ T _x nanoarrays, and the final product was stored at low temperature under argon atmosphere;

(4) Preparation of photoelectrochemical sensor: A layer of gold nanoparticles was sputtered on the surface of TiO ₂ /Ti ₃ C ₂ T _x nanoarray using an ion beam sputtering instrument, the current of the sputtering instrument was adjusted to 10 µA, and the sputtering time was 30 s, to obtain TiO ₂ /Ti ₃ C ₂ T _x /Au; take 6 µL and 20 µmol/L of the aptamer solution with thiol modified at the 3' end and drop it on the surface of TiO ₂ /Ti ₃ C ₂ T _x /Au, Dry naturally at room temperature; drop 3 µL of 1% 6-mercaptohex-1-ol solution on the surface of the modified electrode; continue to drop 6 µL, 10 ng/mL of standard microcystin LR to get Photoelectrochemical sensors.

Example 2

(1) Preparation of TiO ₂ nanoarrays: Spread the FTO glass conductive side up on the bottom of the hydrothermal reactor, and pour a mixture containing 20 mL of deionized water, 20 mL of concentrated hydrochloric acid, and 0.5 mL of tetrabutyl titanate. , incubated at 150 ^o C for 10 h to obtain _TiO nanoarrays, washed with deionized water for several times and dried;

(2) Preparation of single-layer Ti ₃ C ₂ T _x nanosheets: Disperse 0.3 g of accordion-shaped Ti ₃ C ₂ T _x in 20 mL of dimethyl sulfoxide, stir well at room temperature for 25 h to crack the accordion structure Monolayer Ti ₃ C ₂ T _x nanosheets were obtained, then the above mixture was centrifuged at 5000 rpm for 30 min, and the precipitate was washed several times with deionized water to remove all dimethyl sulfoxide, and finally mono layer Ti ₃ C ₂ T was obtained _x nanosheets;

(3) Preparation of TiO ₂ /Ti ₃ C ₂ T _x nanoarrays: The single-layer Ti ₃ C ₂ T _x nanosheets were re-dispersed in a three-necked flask filled with 80 mL of deionized water, and purged with argon bubbling air, followed by sonication in an ice-water bath for 15 h, the obtained product was allowed to stand for 10 h and then the upper layer of colloid was taken; in a plastic petri dish that was purged of air with argon, 100 μL of the upper layer of colloid was drop-coated on the TiO ₂ nanoarray, at room temperature Naturally volatilized for 18 h, calcined at 250 ^o C for 3 h under argon atmosphere to obtain TiO ₂ /Ti ₃ C ₂ T _x nanoarrays, and the final product was stored at low temperature under argon atmosphere;

(4) Preparation of photoelectrochemical sensor: A layer of gold nanoparticles was sputtered on the surface of the TiO ₂ /Ti ₃ C ₂ T _x nanoarray using an ion beam sputtering instrument, the current of the sputtering instrument was adjusted to 20 µA, and the sputtering time was 60 s, to obtain TiO ₂ /Ti ₃ C ₂ T _x /Au; take 6 µL and 80 µmol/L of aptamer solution with thiol modified at the 3' end and drop it on the surface of TiO ₂ /Ti ₃ C ₂ T _x /Au, Air dry naturally at room temperature; drop 3 µL of 1% 6-mercaptohex-1-ol solution on the surface of the modified electrode; continue to drop 6 µL, 100 ng/mL of standard microcystin LR to get the photoelectric chemical sensor.

Example 3

(1) Preparation of _TiO2 nanoarrays: Spread the FTO glass conductive side up on the bottom of the hydrothermal reactor, and pour a mixture containing 45 mL of deionized water, 45 mL of concentrated hydrochloric acid and 1.2 mL of tetrabutyl titanate. , incubated at 160 ^o C for 12 h to obtain TiO ₂ nanoarrays, washed with deionized water several times and dried;

(2) Preparation of single-layer Ti ₃ C ₂ T _x nanosheets: Disperse 0.5 g of accordion-shaped Ti ₃ C ₂ T _x in 25 mL of dimethyl sulfoxide, stir well at room temperature for 36 h to crack the accordion structure Monolayer Ti ₃ C ₂ T _x nanosheets were obtained, then the above mixture was centrifuged at 6000 rpm for 40 min, and the precipitate was washed several times with deionized water to remove all dimethyl sulfoxide, and finally mono layer Ti ₃ C ₂ T was obtained _x nanosheets;

(3) Preparation of TiO ₂ /Ti ₃ C ₂ T _x nanoarrays: The single-layer Ti ₃ C ₂ T _x nanosheets were re-dispersed in a three-necked flask filled with 100 mL of deionized water, and purged with argon bubbling air, followed by sonication in an ice-water bath for 18 h, the obtained product was allowed to stand for 12 h and the upper layer of colloid was taken; in a plastic petri dish evacuated with argon, 200 μL of the upper layer of colloid was drop-coated on the TiO ₂ nanoarray, at room temperature Naturally volatilized for 24 h, calcined at 300 ^o C for 3 h under argon atmosphere to obtain TiO ₂ /Ti ₃ C ₂ T _x nanoarrays, and the final product was stored at low temperature under argon atmosphere;

(4) Preparation of photoelectrochemical sensor: A layer of gold nanoparticles was sputtered on the surface of TiO ₂ /Ti ₃ C ₂ T _x nanoarray using an ion beam sputtering instrument, the current of the sputtering instrument was adjusted to 30 µA, and the sputtering time was 80 s, to obtain TiO ₂ /Ti ₃ C ₂ T _x /Au; take 6 µL, 100 µmol/L of aptamer solution with thiol modified at the 3' end and drop it on the surface of TiO ₂ /Ti ₃ C ₂ T _x /Au, Dry naturally at room temperature; drop 3 µL of 1% 6-mercaptohex-1-ol solution on the surface of the modified electrode; continue to drop 6 µL, 500 ng/mL of standard microcystin LR to get the photoelectric chemical sensor.

Example 4

The prepared photoelectrochemical sensor was used for the detection of microcystin LR. The electrochemical workstation was used for testing with a three-electrode system. The Ag/AgCl electrode was used as the reference electrode, the platinum wire electrode was used as the counter electrode, and the prepared sensor was used as the working electrode. The test was carried out in an aqueous solution with a pH of 10; the time-amperometric method was used to detect the microcystin LR, the running time was 120s, and the light source wavelength was 450 nm; Photocurrent, draw the working curve; replace the microcystin LR standard solution with the lake water sample solution to be tested for detection.

Example 5

The prepared photoelectrochemical sensor was used for the detection of microcystin LR. The electrochemical workstation was used for testing with a three-electrode system. The Ag/AgCl electrode was used as the reference electrode, the platinum wire electrode was used as the counter electrode, and the prepared sensor was used as the working electrode. The test was carried out in an aqueous solution with a pH of 12; the microcystin LR was detected by the time-amperometry method, the running time was 120s, and the light source wavelength was 450 nm; Photocurrent, draw the working curve; replace the microcystin LR standard solution with the lake water sample solution to be tested for detection.

The photoelectrochemical sensor for detecting microcystin LR prepared by the invention is successfully used in the detection of microcystin LR samples in water, and the recovery rate is between 92.3% and 105.4%.

Claims (2)

1. A method for preparing a photoelectrochemical sensor for detecting microcystin LR, characterized in that it comprises the following steps: (1) Preparation of TiO ₂ nanoarrays: laying the conductive surface of FTO glass on a hydrothermal surface At the bottom of the reaction kettle, pour a mixture containing 8-45 mL of deionized water, 8-45 mL of concentrated hydrochloric acid and ^0.2-1.2 mL of tetrabutyl titanate. Washed with ionized water for several times and dried to obtain _TiO2 nanoarrays; Monolayer Ti ₃ C ₂ T _x nanosheets were prepared by dispersing 0.1 ~ 0.5 g of accordion-shaped Ti ₃ C ₂ T _x in 15 ~ 25 mL of dimethyl sulfoxide, and stirring well at room temperature for 18 ~ 36 h to make it The accordion structure was cracked to obtain monolayer Ti ₃ C ₂ T _x nanosheets, and then the above mixture was centrifuged at 4000 ~ 6000 rpm for 20 ~ 40 min, and the precipitate was washed with deionized water for several times to remove all dimethyl sulfoxide to obtain monolayer. layer _{Ti3C2Tx nanosheets ;} Preparation of TiO ₂ /Ti ₃ C ₂ T _x nanoarrays: The monolayer Ti ₃ C ₂ T _x nanosheets from step (2) were re-dispersed in a three-necked flask filled with 20 ~ 100 mL of deionized water, under argon gas Bubble to remove the air, and then sonicate in an ice-water bath for 4 to 18 hours. The obtained product was left standing for 8 to 12 hours, and then the upper layer of colloid was taken; 50 to 200 μL of the upper layer of colloid was dropped into a plastic petri dish with argon to remove the air. Coated on TiO ₂ nanoarrays, naturally volatilized at room temperature for 12 ~ 24 h, and calcined at 200 ~ 300 ^o C for 2 ~ 3 h in an argon atmosphere to obtain TiO ₂ /Ti ₃ C ₂ T _x nanoarrays, the final product was in argon Low temperature storage in atmospheric environment; (4) Preparation of photoelectrochemical sensors: Sputtering a layer of gold nanoparticles on the surface of TiO ₂ /Ti ₃ C ₂ T _x nanoarrays using an ion beam sputtering instrument, adjusting the current of the sputtering instrument to 10 ~ 30 µA, and the sputtering time 30 ~ 80 s to obtain TiO ₂ /Ti ₃ C ₂ T _x /Au; take 6 µL, 20 ~ 100 µmol/L of the aptamer solution with thiol modified at the 3' end dropwise added to TiO ₂ /Ti ₃ C ₂ T _x /Au surface, dry naturally at room temperature; drop 3 µL of 1% 6-mercaptohexan-1-ol solution on the surface of the modified electrode; continue to drop 6 µL of standard microcapsules with different concentrations Cytotoxin LR completes sensor construction. 2. the prepared sensor of a kind of photoelectrochemical sensor preparation method for detecting microcystin LR according to claim 1, is characterized in that, for detecting microcystin LR step is as follows: (1) The electrochemical workstation was used for testing with a three-electrode system, the Ag/AgCl electrode was used as the reference electrode, the platinum wire electrode was used as the counter electrode, and the prepared sensor was used as the working electrode. (2) Microcystin LR was detected by time-amperometric method, the running time was 120 s, and the light source wavelength was 450 nm; (3) After the electrodes are placed, turn on the light for 12 s every 12 s, record the photocurrent, and draw the working curve; (4) Replace the standard microcystin LR standard solution with the lake water sample solution to be tested for detection.