WO2020134305A1 - Method for quantitatively measuring content of thiol ligand on quantum dot surface - Google Patents

Abstract

A method for quantitatively measuring a content of a thiol ligand on a quantum dot surface. Bismuth vanadate (BiVO4) is a visible light responding semiconductor material, has a good photocatalytic activity, and also has a good photoelectric property. Photoelectrochemical (PEC) test is performed, during illumination, an electron hole in a ground state is separated, and it is detected that transited electrons can generate a current. Bismuth sulfide (Bi2S3), as a semiconductor material, can form a Bi2S3-BiVO4 heterojunction with the bismuth vanadate; such Bi2S3-BiVO4 heterojunction can improve the separation efficiency of the hole and the electron, and has a larger current strength than BiVO4 when performing PEC test. A proportion of the bismuth sulfide and the bismuth vanadate is within a certain range; the content of Bi2S3 is proportional to a size of a photocurrent; and by testing the size of the photocurrent, quantitative calculation of Bi2S3 can be implemented, i.e., the content of the thiol ligand on the quantum dot surface is obtained.

Description

Method for quantitatively detecting content of thiol ligand on surface of quantum dot Technical field

The present disclosure relates to the field of quantum dot light emitting devices, and in particular to a method for quantitatively detecting the content of thiol ligand on the surface of quantum dots.

Background technique

During the synthesis of quantum dots, ligands will be added, and the ligands will affect the nucleation and growth, morphology, fluorescence properties and stability of quantum dots. The ligands are distributed on the surface of quantum dots, usually one or more types, such as thiols, amines, carboxylic acids, phosphines. Mercaptans generally include octyl mercaptan, dodecanethiol, octadecanethiol, disubstituted dithiols, etc.; amines generally have dodecylamine, oleylamine, etc.; carboxylic acids have oleic acid, etc.; phosphines have two Octylphosphine, trioctylphosphine, hexylphosphonic acid, tetradecylphosphonic acid, octadecylphosphonic acid, etc. The amount of ligand added is known, but part of the ligand is washed away during the quantum dot cleaning process, and the remaining part of the ligand is bound to the surface of the quantum dot. The content of the bound ligand is unknown, and this distribution The volume content has an important guiding role in the theoretical calculation, further calculation of the reaction charge, and the study of the luminescence mechanism. Therefore, it is of great significance to find a method that can quantitatively calculate the ligand content on the surface of quantum dots.

Summary of the invention

In view of the above shortcomings of the prior art, the purpose of the present disclosure is to provide a method for quantitatively detecting the content of thiol ligand on the surface of quantum dots, and aims to provide a method for quantitatively calculating the content of thiol ligand on the surface of quantum dots.

The technical solutions of the present disclosure are as follows:

A method for quantitatively detecting the content of thiol ligand on the surface of quantum dots, which includes the steps of:

A thiol solution with different molar concentrations is prepared, and the preformed bismuth vanadate film is placed in a thiol solution to react to obtain a first Bi ₂ S ₃ -BiVO ₄ heterojunction, and the first Bi ₂ S ₃ -BiVO ₄ Perform photoelectric test on the heterojunction, record the size of the photocurrent, and determine the corresponding relationship between the thiol concentration and the photocurrent according to the thiol concentration and the photocurrent;

Put the bismuth vanadate film into the solution of the sub-point to be measured for reaction, in which the thiol ligand is bound to the surface of the quantum dot to obtain a second Bi ₂ S ₃ -BiVO ₄ heterojunction film; for the second Bi ₂ The photoelectric test is performed on the S ₃ -BiVO ₄ heterojunction film to obtain the photocurrent value, and the thiol concentration value is obtained according to the corresponding relationship between the thiol concentration and the photocurrent and the photocurrent value.

Beneficial effect: In the present disclosure, bismuth vanadate (BiVO ₄ ) is a visible light-responsive semiconductor material that has good photocatalytic activity and, at the same time, has good photoelectric properties. In the photoelectric test (PEC), when the light is irradiated, the electron holes in the ground state are separated, and the transition electrons can detect the current. Bismuth sulfide (Bi ₂ S ₃ ) as a semiconductor material can form a Bi ₂ S ₃ -BiVO ₄ heterojunction with bismuth vanadate. This heterojunction Bi ₂ S ₃ -BiVO ₄ can improve the hole and electron The separation efficiency is higher than that of BiVO ₄ when conducting PEC test. Within a certain range of the ratio of bismuth sulfide to bismuth vanadate, the content of Bi ₂ S ₃ is proportional to the size of the photocurrent. By measuring the size of the photocurrent, the quantitative calculation of Bi ₂ S ₃ can be achieved, that is, the sulfur on the surface of the quantum dot can be obtained Alcohol ligand content.

BRIEF DESCRIPTION

FIG. 1 is a schematic flowchart of a method for quantitatively detecting the content of thiol ligand on the surface of a quantum dot provided by an embodiment of the present disclosure.

FIG. 2 is a mechanism diagram of a method for quantitatively detecting the content of thiol ligand on the surface of a quantum dot provided by an embodiment of the present disclosure.

detailed description

The present disclosure provides a method for quantitatively detecting the content of thiol ligands on the surface of quantum dots. To make the purposes, technical solutions, and effects of the present disclosure clearer and more specific, the present disclosure will be described in further detail below. It should be understood that the specific embodiments described herein are only used to explain the present disclosure and are not intended to limit the present disclosure.

In the process of quantum dot synthesis, the amount of ligand added is known, but part of the ligand is washed away during the quantum dot cleaning process, and the remaining part of the ligand is bound to the surface of the quantum dot. The content of the bound ligand is It is unknown, and the content of this distribution body has an important guiding role in theoretical calculations, further calculation of reaction feed volume, and the study of luminescence mechanism. Therefore, the embodiments of the present disclosure provide a method for quantitatively calculating the ligand content on the surface of quantum dots.

Please refer to FIG. 1. FIG. 1 is a schematic flowchart of a method for quantitatively detecting the content of thiol ligand on the surface of a quantum dot provided by an embodiment of the present disclosure. As shown in the figure, it includes the steps of:

S10. Prepare thiol solutions with different molar concentrations, and place the pre-made bismuth vanadate film into the thiol solution for reaction to obtain a first Bi ₂ S ₃ -BiVO ₄ heterojunction film. The first Bi ₂ S ₃ -Perform photoelectric test on the BiVO ₄ heterojunction film, record the size of the photocurrent, and determine the corresponding relationship between the thiol concentration and the photocurrent according to the thiol concentration and the photocurrent;

S20. Put the bismuth vanadate film into the sub-point solution to be measured for reaction, wherein the surface of the quantum dot is bound with a thiol ligand to obtain a second Bi ₂ S ₃ -BiVO ₄ heterojunction film; The photoelectric test is performed on the Bi ₂ S ₃ -BiVO ₄ heterojunction film to obtain the photocurrent value, and the thiol concentration value is obtained according to the corresponding relationship between the thiol concentration and the photocurrent and the photocurrent value.

In some embodiments, the step of determining the corresponding relationship between the thiol concentration and the photocurrent according to the thiol concentration and the photocurrent includes: establishing a standard curve according to the thiol concentration and the photocurrent to obtain the thiol concentration The fitting curve with photocurrent y=kx+b R ² >0.9900, where x is the thiol concentration, y is the photocurrent, k is the slope, b is the intercept, and R ² is the coefficient.

In the embodiments of the present disclosure, target thiol solutions of different concentrations are prepared, photoelectric tests are performed, and a standard curve is drawn on the concentration and current size, and a fitting curve is obtained, which is used for the calculation of the thiol content in the quantum dot sample. Specifically, BiVO ₄ is a visible light-responsive semiconductor material with good photoelectric properties. As shown in Figure 2, a photoelectric test (PEC test) is performed. When the light is irradiated, the electron holes in the ground state are separated, and the transition electrons can generate a current. The quantum dot solution, the mercapto group on the thiol has a high Active, it can undergo in-situ ion exchange with the vanadate of bismuth vanadate to generate bismuth sulfide, thereby forming a Bi ₂ S ₃ -BiVO ₄ heterojunction at the reaction interface; Bi ₂ S ₃ -BiVO ₄ heterojunction can increase the hole In the PEC test, the separation efficiency of electrons is within a certain range. The content of Bi ₂ S ₃ is proportional to the size of photocurrent. By measuring the size of photocurrent, quantitative calculation of Bi ₂ S ₃ can be achieved. And other kinds of ligands, such as -NH _2, -COOH, -PO ₃ ^4- presence and not BiVO ₄ Bi ₂ S ₃ -BiVO ₄ is formed, it will not affect the magnitude of the photocurrent. Although powdered bismuth vanadate can react with mercapto groups, it is impossible to know how much reaction has occurred. By making powdered bismuth vanadate into a solid film, it can be conveniently tested and the specific current size can be accurately calculated. Step In some embodiments, the standard curve was established comprises: 5 a preformed bismuth vanadate membrane were placed thiol concentration ranging from 10 ^-5 -10 ^-3 mol / L (such as 1 * 10 ^{- 4} mol/L, 2*10 ^-4 mol/L, 4*10 ^-4 mol/L, 8*10 ^-4 mol/L, 10 ^-3 mol/L; or 1*10 ^-5 mol/L, 2 *10 ^-5 mol/L, 4*10 ^-5 mol/L, 8*10 ^-5 mol/L, 10 ^-4 mol/L;) in n-hexane/heptane/n-octane solution, fully react 0.5 -2h, the bismuth vanadate reacts with the mercapto group to form the first Bi ₂ S ₃ -BiVO ₄ heteroconjunctiva, take out the first Bi ₂ S ₃ -BiVO ₄ heteroconjunctiva, rinse it with distilled water, and clean the first Bi ₂ S ₃ -BiVO ₄ heterojunction is put into the photoelectric test cell to test, record the size of the photocurrent, make a standard curve for the thiol concentration x and the photocurrent size y (the ratio of bismuth sulfide to bismuth vanadate is within a certain range, Bi ₂ S The content of ₃ is proportional to the size of the photocurrent. Since it is not safe to ensure that the thiol can fully react with the bismuth vanadate, in the actual measurement, the relationship between the initial thiol concentration and the photocurrent is established, regardless of the intermediate reaction process, so the test result is more Accurate.), find the fitting curve of this thiol concentration and photocurrent y=kx+b R ² >0.9900.

In some embodiments, an excessive amount of prefabricated bismuth vanadate film is placed in a thiol solution for reaction to ensure complete thiol reaction and improve calculation accuracy.

In some embodiments, the thiol solution is a solution added with a thiol ligand to the quantum dot solution, so that the solution is as consistent as possible with the sub-point solution to be measured, thereby improving the accuracy of calculation.

In some embodiments, during the preparation of the quantum dot solution, the thiol ligand is gradually added to the quantum dot solution, and the bismuth vanadate film is placed into the quantum dot solution after each addition of the thiol ligand React. In this embodiment, the bismuth vanadate film is placed in the quantum dot solution after adding the thiol ligand for reaction, and each time the reaction is performed on the formed second Bi ₂ S ₃ -BiVO ₄ heterojunction film Photoelectric test to calculate the concentration of thiol. In this way, testing while adding can make the calculated thiol content as much as possible as the thiol content bound on the surface of the quantum dot, thereby minimizing the calculation error.

In some embodiments, the step of performing photoelectric testing on the first Bi ₂ S ₃ -BiVO ₄ heterojunction film includes: providing an electrolyte, establishing a three-electrode system in the electrolyte, wherein the first Bi ₂ The S ₃ -BiVO ₄ heterojunction is used as a working electrode, the three-electrode system is connected to an electrochemical workstation, and a photoelectric test is performed to obtain a photocurrent magnitude.

In some specific embodiments, the step of performing the photoelectric test on the first Bi ₂ S ₃ -BiVO ₄ heterojunction film specifically includes: the photoelectric performance test uses a CHI600E electrochemical workstation, and the light source is a 500W xenon lamp with a filter added (λ>400nm), the electrolyte in the photoelectric test cell is 0.5mol/LNa ₂ SO ₄ solution; establish a standard three-electrode system, using the first Bi ₂ S ₃ -BiVO ₄ heterojunction as the working electrode, and the platinum electrode as the pair For the electrode, an Ag/AgCl (saturated KCl solution) electrode is used as a reference electrode; the three-electrode system is connected to an electrochemical workstation; a photoelectric test is performed to obtain the magnitude of photocurrent.

In some specific embodiments, the step of measuring the sample includes: placing three pieces of the bismuth vanadate film in the solution of the sub-point to be measured and reacting, wherein the surface of the quantum dot is bound with a thiol ligand to obtain a second Bi ₂ S ₃ -BiVO ₄ heterojunction; perform photoelectric test on the second Bi ₂ S ₃ -BiVO ₄ heterojunction, record the magnitude of photocurrent y, and substitute the fitting curve to calculate the thiol concentration x. The average of the three results is the concentration of thiol in the quantum dot, and the corresponding thiol content is calculated according to the volume of the solution. It should be noted that the bismuth vanadate film in the sample measurement and the bismuth vanadate film in the established standard curve have the same specifications. In some embodiments, the reaction time of the bismuth vanadate film and thiol in the established standard curve is the same as the reaction time of the bismuth vanadate film and thiol in the sample determination. More preferably, the reaction time is 0.5-2h.

In some embodiments, the mercaptan is an organic compound with a mercapto group, and generally includes one or more of octyl mercaptan, dodecyl mercaptan, stearyl mercaptan, disubstituted dithiol, and the like.

In some embodiments, the quantum dots include one or more of group II-VI quantum dots, group III-V quantum dots, group IV-VI quantum dots, and the like. As an example, the group II-VI quantum dots are selected from one or more of CdSe, CdS, ZnSe, ZnS, CdTe, ZnTe, CdZnS, ZnSeS, CdSeS, CdSeSTe, CdZnSeSTe, etc.; the group III-V quantum The dots are selected from one or more of InP, InAs, InAsP, etc.; the group IV-VI quantum dots are selected from one or more of PbS, PbSe, PbSeS, PbSeTe, PbSTe, etc.

In this embodiment, bismuth vanadate can be prepared by solvothermal method, chemical precipitation method or sol-gel method. Preferably, bismuth vanadate is prepared by chemical precipitation. The detailed preparation process is as follows:

Solvothermal method: Dissolve bismuth nitrate pentahydrate and ammonium metavanadate in acid and alkali solution respectively, add surfactant or metal chelating agent, adjust pH to a certain value with acid or alkali, put it in the reaction kettle, and react at a certain temperature And time, wash and dry for use.

Example 1: Weigh 4.8507g Bi(NO ₃ ) ₃ ·5H ₂ O dissolved in 5mL concentrated HNO ₃ and dilute with water to 20mL (4.0mol/L), magnetic stirring for 10min to obtain solution A; then weigh 1.1698g NH ₄ Dissolve VO ₃ in 20mL4.0mol/LNaOH solution, add 2.000g EDTA and stir to obtain solution B; then add solution B dropwise to solution A and continue to stir, while adding 2.0mol/LNaOH dropwise during stirring and dissolution The pH of the mixed solution was adjusted by the solution to 5.0. After the magnetic stirring was continued for 30 min, the mixture was transferred to a stainless steel hydrothermal kettle lined with 100 mL of polytetrafluoroethylene for sealing, the volume of the mixed solution was controlled to 80 mL, and the reaction was carried out at 180°C for 24 h. After the reaction kettle was naturally cooled, the upper liquid was removed, vacuum filtered and washed with deionized water and absolute ethanol to neutrality, vacuum dried at 65°C for 12h, and ground in an agate mortar to obtain a BiVO ₄ sample.

Example 2: Weigh 1.2127g Bi(NO ₃ ) ₃ ·5H ₂ O and 0.2925g NH ₄ VO ₃ were dissolved in 50mL 2.0 mol/LHNO ₃ and 50mL 2.0mol/LNH ₃ · H ₂ O, magnetic stirring for 10min , Named solution A and solution B respectively; dissolve 0.5000g SDS (sodium dodecyl sulfate) in 30.0mL distilled water and add it to solution A; then add solution B dropwise to solution A and continue Stir for 30 min, adjust the pH of the mixed solution to 7.0 with NH ₃ ·H ₂ O, continue the magnetic stirring for 2 h, then transfer the mixture to three 50 mL hydrothermal kettles, control the volume of the mixed solution to 40 mL, and react at 180 °C for 24 h After the reactor was cooled naturally, the upper liquid was removed, vacuum filtered and washed with deionized water and absolute ethanol to neutrality, vacuum dried at 65°C for 12h, and ground in an agate mortar to obtain a BiVO ₄ sample.

Chemical precipitation method: Dissolve bismuth nitrate pentahydrate and ammonium metavanadate in acid and alkali solution respectively, slowly add dropwise, calcinate for a certain temperature and time, and grind for standby.

Example: 8.985 g of bismuth nitrate pentahydrate was dissolved in 1.34 mol/L 150 mL of glacial acetic acid, 2.166 g of ammonium metavanadate was dissolved in 0.5 mol/L 150 mL of NaOH aqueous solution, and it was completely dissolved under ultrasonic conditions. Under ultrasonic conditions, the NH ₄ VO ₃ solution was quickly poured into the Bi(NO ₃ ) ₃ solution, and the solution gradually turned into a bright yellow flocculent suspension. After continuing ultrasonication for 15 min, it was filtered with suction, washed with pure water and absolute alcohol, and dried at 70°C to obtain a precursor of bismuth vanadate. After grinding the precursor into a crucible and calcining at 400°C for 2 hours, the resulting powder is BiVO ₄ . The small particle size is because the reaction conditions before the calcination are relatively mild, the precursor particle size is small, only the crystal form is affected after calcination, and the particle size is not affected. The particle size is small, the film formation effect is better, the photoelectric performance is better, and the stability Strong, not easy to fall off.

Sol-gel method: Dissolve bismuth nitrate pentahydrate and ammonium metavanadate in acid and alkali solutions respectively, add citric acid, slowly add dropwise, put in an oven to evaporate the solvent, calcinate, and grind for use.

Example: Dissolve 8.985 g of bismuth nitrate pentahydrate in 10 mL of 1 mol/L dilute nitric acid, add 7.685 g of citric acid, add 10 mL of distilled water after dissolution, magnetically stir, adjust the pH to 7 with ammonia water, called A solution; 2.166 g partial Ammonium vanadate and 7.685g of citric acid are dissolved in 20mL of boiling water, which is called B solution. Add solution A dropwise into solution B, magnetically stir, and adjust the pH to 7. Use ammonia to adjust the pH to 7. React at 80°C for 3h, place in an oven to evaporate the solvent at 70°C to obtain a sol, grind the sol into a crucible, and calcine at 500°C for 4h , The resulting powder is BiVO ₄ .

In this embodiment, the bismuth vanadate film can be prepared by a solution method or an electrospinning method. The advantages of these two methods are that the prepared bismuth vanadate film is even and thin, the amount of bismuth vanadate present per unit area is controllable, and the performance difference of each film is small, so as to ensure repeatability and accuracy of subsequent quantitative tests .

Spin coating method: take 20mg of bismuth vanadate powder, dissolve in 2mL ethanol, ultrasonically disperse for 30min to obtain bismuth vanadate suspension; ultrasonically clean FTO glass with acetone, ethanol, and water for 15min, and place clean FTO glass on the spin On the applicator, add 50 μL of bismuth vanadate suspension, spin-coating condition is 2000r/s 30s, repeat 10 times. Bake on the hot plate for 1 min to completely volatilize the solvent to obtain a bismuth vanadate film.

Electrostatic spinning method: Take 200mg of bismuth vanadate powder in ultrasonic dispersion in 10mL of ethanol/dimethylformamide, slowly add 0.5-1.5g PVDF/PVP/PAN, stir until all are dissolved, then the spinning solution is obtained. Take 8mL of spinning solution into the syringe, connect the tip of the syringe to the Teflon tube, connect the other end of the tube with a 21 gauge needle, and carefully squeeze the spinning solution to the needle to overflow the spinning solution. Wash the FTO glass with acetone, ethanol, and water for 15 min each, and place the clean FTO glass on the roller of the electrospinning machine. The distance between the needle and the received FTO glass is 10-30cm, the voltage is 20-25V, and the spinning solution flow rate is 0.3-1.5mL/h. Spinning is completed. The spun glass is placed in an oven and cured at 80-110°C for 12 hours to obtain a bismuth vanadate film.

In summary, the present disclosure provides a method for quantitatively detecting the content of thiol ligand on the surface of quantum dots. In the present disclosure, bismuth vanadate (BiVO ₄ ) is a visible light-responsive semiconductor material that has good photocatalytic activity and, at the same time, has good photoelectric properties. In the photoelectric test (PEC), when the light is irradiated, the electron holes in the ground state are separated, and the transition electrons can detect the current. Bismuth sulfide (Bi ₂ S ₃ ) as a semiconductor material can form a Bi ₂ S ₃ -BiVO ₄ heterojunction with bismuth vanadate. This heterojunction Bi ₂ S ₃ -BiVO ₄ can improve the hole and electron The separation efficiency is higher than that of BiVO ₄ when conducting PEC test. Within a certain range of the ratio of bismuth sulfide to bismuth vanadate, the content of Bi ₂ S ₃ is proportional to the size of the photocurrent. By measuring the size of the photocurrent, the quantitative calculation of Bi ₂ S ₃ can be achieved, that is, the sulfur on the surface of the quantum dot can be obtained Alcohol ligand content.

It should be understood that the application of the present disclosure is not limited to the above examples, and those of ordinary skill in the art may make improvements or changes based on the above description, and all such improvements and changes shall fall within the protection scope of the claims appended to the present disclosure.

Claims (19)

1. A method for quantitatively detecting the content of thiol ligand on the surface of quantum dots, characterized in that it includes the steps of:

   A thiol solution with different molar concentrations is prepared, and the preformed bismuth vanadate film is placed in a thiol solution to react to obtain a first Bi ₂ S ₃ -BiVO ₄ heterojunction, and the first Bi ₂ S ₃ -BiVO ₄ Perform photoelectric test on the heterojunction, record the size of the photocurrent, and determine the corresponding relationship between the thiol concentration and the photocurrent according to the thiol concentration and the photocurrent;

   Put the bismuth vanadate film into the solution of the sub-point to be measured for reaction, in which the thiol ligand is bound to the surface of the quantum dot to obtain a second Bi ₂ S ₃ -BiVO ₄ heterojunction film; for the second Bi ₂ The photoelectric test is performed on the S ₃ -BiVO ₄ heterojunction film to obtain the photocurrent value, and the thiol concentration value is obtained according to the corresponding relationship between the thiol concentration and the photocurrent and the photocurrent value.
2. The method for quantitatively detecting the content of thiol ligand on the surface of a quantum dot according to claim 1, wherein the corresponding relationship between the concentration of the thiol and the photocurrent: fitting curve y=kx+b R ² >0.9900, wherein x is the thiol concentration, y is the photocurrent, k is the slope, b is the intercept, and R ² is the coefficient.
3. The method for quantitatively detecting the content of thiol ligands on the surface of quantum dots according to claim 1, characterized in that an excessive amount of prefabricated bismuth vanadate film is put into a thiol solution for reaction.
4. The method for quantitatively detecting the content of thiol ligand on the surface of a quantum dot according to claim 1, wherein the thiol solution is a solution in which a thiol ligand is added to the quantum dot solution.
5. The method for quantitatively detecting the content of thiol ligand on the surface of a quantum dot according to claim 1, characterized in that, in the preparation process of the quantum dot solution, the thiol ligand is added to the quantum dot solution one by one in order to add the vanadium The bismuth acid film is put into the quantum dot solution after each addition of thiol ligand to react.
6. The method for quantitatively detecting the content of thiol ligand on the surface of a quantum dot according to claim 1, wherein the step of performing photoelectric test on the first Bi ₂ S ₃ -BiVO ₄ heterojunction film includes: providing an electrolyte, A three-electrode system is established in the electrolyte, wherein the first Bi ₂ S ₃ -BiVO ₄ heterojunction is used as a working electrode, the three-electrode system is connected to an electrochemical workstation, and a photoelectric test is performed to obtain a photocurrent magnitude .
7. The method for quantitatively detecting the content of thiol ligand on the surface of a quantum dot according to claim 6, wherein the step of performing photoelectric test on the first Bi ₂ S ₃ -BiVO ₄ heterojunction film specifically includes: photoelectric performance test Use an electrochemical workstation, the light source is a xenon lamp with a filter, and the electrolyte in the photoelectric test cell is a Na ₂ SO ₄ solution; establish a standard three-electrode system and use the first Bi ₂ S ₃ -BiVO ₄ heterojunction as the working electrode The platinum electrode was used as the counter electrode, and the Ag/AgCl electrode was used as the reference electrode; the three-electrode system was connected to an electrochemical workstation; a photoelectric test was performed to obtain the magnitude of the photocurrent.
8. The method for quantitatively detecting the content of thiol ligand on the surface of a quantum dot according to claim 1, wherein the bismuth vanadate film is prepared by a solution method or an electrospinning method.
9. The method for quantitatively detecting the content of thiol ligand on the surface of quantum dots according to claim 1, characterized in that bismuth vanadate is prepared by a solvothermal method, a chemical precipitation method or a sol-gel method.
10. The method for quantitatively detecting the content of thiol ligand on the surface of quantum dots according to claim 9, characterized in that bismuth vanadate is prepared by chemical precipitation.
11. The method for quantitatively detecting the content of thiol ligands on the surface of quantum dots according to claim 10, characterized in that bismuth nitrate pentahydrate and ammonium metavanadate are dissolved in acid and alkali solutions respectively, the two solutions are mixed and calcined The bismuth vanadate is obtained.
12. The method for quantitatively detecting the content of thiol ligands on the surface of quantum dots according to claim 1, characterized in that the step comprises: placing 3 pieces of the bismuth vanadate film in the solution of the sub-dots to be measured for reaction, wherein the quantum dots A thiol ligand is bound to the surface to obtain a second Bi ₂ S ₃ -BiVO ₄ heterojunction; the second Bi ₂ S ₃ -BiVO ₄ heterojunction is photoelectrically tested to obtain a photocurrent value, which is substituted into the fitting curve The thiol concentration is calculated, and the average of the three results is the thiol concentration in the quantum dot.
13. The method for quantitatively detecting the content of thiol ligands on the surface of quantum dots according to claim 1, characterized in that the reaction time of the bismuth vanadate film and thiol in the established standard curve and the bismuth vanadate film in the determination of the sample Same reaction time as mercaptan.
14. The method for quantitatively detecting the content of thiol ligand on the surface of quantum dots according to claim 13, wherein the reaction time is 0.5-2h.
15. The method for quantitatively detecting the content of thiol ligand on the surface of a quantum dot according to claim 1, wherein the thiol includes one of octanethiol, dodecanethiol, octadecanethiol and disubstituted dithiol One or more.
16. The method for quantitatively detecting the content of thiol ligand on the surface of quantum dots according to claim 1, wherein the quantum dots include group II-VI quantum dots, group III-V quantum dots and group IV-VI quantum dots One or more.
17. The method for quantitatively detecting the content of thiol ligands on the surface of quantum dots according to claim 16, wherein the group II-VI quantum dots are selected from CdSe, CdS, ZnSe, ZnS, CdTe, ZnTe, CdZnS, ZnSeS, One or more of CdSeS, CdSeSTe, and CdZnSeSTe.
18. The method for quantitatively detecting the content of thiol ligands on the surface of quantum dots according to claim 16, wherein the group III-V quantum dots are selected from one or more of InP, InAs and InAsP.
19. The method for quantitatively detecting the content of thiol ligands on the surface of quantum dots according to claim 16, wherein the group IV-VI quantum dots are selected from one or more of PbS, PbSe, PbSeS, PbSeTe, and PbSTe .

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