Indium zinc selenium sulfur phosphide quantum dot material, preparation method and photoelectrochemical cell

Abstract

The invention relates to an indium zinc selenium sulfur phosphide quantum dot material, a preparation method and a photoelectrochemical cell, and belongs to the technical field of solar photoelectric conversion, and the preparation method comprises the following steps: synthesizing indium phosphide quantum dots; synthesizing indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots; synthesizing a series of surface ligand exchanged indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots; preparing a series of novel quantum dot sensitized photo-anodes and assembling the photo-anodes into a photoelectrochemical cell; the invention also comprises an indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivation quantum dot material and a photochemical cell using the material as a photoanode. The preparation method has the beneficial effects that the separation / transfer efficiency of photo-generated excitons in the quantum dots is reasonably regulated and controlled by introducing vacancy sites and a surface ligand exchange strategy, and the problems of fast recombination of photo-excited electrons and holes and low photoelectric conversion efficiency of traditional quantum dots are effectively solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar photoelectric conversion, and in particular relates to an indium zinc selenide sulfur quantum dot material, a preparation method and a photoelectrochemical cell. Background Art

[0002] Photoelectrochemical cells (PECs) are devices that efficiently and greenly convert solar energy into electrical / chemical energy through artificial photosynthesis. Semiconductor materials with light-absorbing properties play an indispensable role as electrode modules in PEC devices. Recently, colloidal semiconductor quantum dots (QDs) have shown great potential in light-driven PEC applications due to their unique high light absorption coefficient and size-tunable absorption / emission optical properties. However, current quantum dot-based PEC devices still face limitations, such as the use of quantum dots containing heavy metal elements (Cd or Pb) that are harmful to the ecological environment. Therefore, the development of environmentally friendly quantum dot materials that do not contain heavy metal elements is of practical significance for achieving green development in the future.

[0003] Furthermore, the presence of quantum dot surface effects inevitably leads to the formation of excessive defect states / traps, resulting in severe non-radiative recombination and low carrier transport efficiency. Controlling an appropriate amount of vacancy sites can act as hole defect / trap states, thereby capturing holes and promoting carrier separation. At the same time, a customized quantum dot surface ligand exchange strategy can replace long-chain ligands with inherent weak bond properties and steric effects, thereby driving efficient photogenerated exciton separation and transfer, and thus achieving high-performance solar photovoltaic conversion. Summary of the Invention

[0004] The present invention provides an indium zinc selenide sulfur quantum dot material, a preparation method and a photoelectrochemical cell, which are used to solve the technical problem that traditional quantum dots have fast photoexcited electron-hole recombination but low photoelectric conversion efficiency. By replacing the long-chain ligands on the surface of indium phosphide / zinc selenide sulfur-zinc vacancy quantum dots through a series of controllable ligand exchanges, the problems of low photogenerated carrier separation / transfer efficiency and photoelectric conversion efficiency of traditional quantum dots are effectively solved.

[0005] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0006] A method for preparing an indium zinc selenide sulfur quantum dot material comprises the following steps:

[0007] Step S1: An indium source, a zinc source, and a solvent are sequentially added to a 50 mL three-necked flask, degassed at 130-150° C., then heated to 200° C. under nitrogen protection, a phosphorus source is injected, and the temperature is kept for 1-2 hours to obtain indium phosphide quantum dots;

[0008] Step S2: injecting a zinc precursor and a selenium / sulfur precursor into the indium phosphide quantum dots obtained in step S1 in sequence, heating the mixture to 240° C. and reacting for 30-50 minutes, cooling the mixture to 120° C., and then cooling the mixture to room temperature in a cold water bath reactor to obtain indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots;

[0009] Step S3: heating the indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots obtained in step S2 to 250-270° C. in an inert gas, then injecting a chlorine precursor and keeping the temperature for 15-30 minutes, cooling the temperature to 120° C. and then cooling the temperature to room temperature in a cold water bath reactor to obtain indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dots;

[0010] Step S4: immersing titanium dioxide / fluorine-doped tin oxide in a quantum dot / n-hexane solution, and using electrophoretic deposition at a voltage of 150-220 V for 1.5-3 hours to obtain an indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dot material.

[0011] Optionally, in step S1, the indium source, zinc source and solvent used are indium chloride, zinc chloride and oleylamine, respectively, and the phosphorus source is a mixed solution of tri(dimethylamino)phosphine and oleylamine; when oleylamine is added for the first time, the mass volume (mg / mL) ratio of indium chloride to oleylamine is 70-80:5-10; in the mixed solution of triphosphine and oleylamine, the volume ratio of the mixed solution of tri(dimethylamino)phosphine and oleylamine is 1:2.

[0012] Optionally, in step S2 and step S3, zinc stearate is dispersed in 1-octadecene to obtain a zinc precursor; selenium powder and sulfur powder are dispersed in trioctylphosphine to obtain a selenium / sulfur precursor; and zinc chloride is dispersed in ethanol to obtain a chlorine precursor.

[0013] Optionally, in step S2 and step S3, the concentration of zinc stearate in the zinc precursor is 0.2-0.3 mmol / mL; the concentration of selenium powder / sulfur powder in the selenium / sulfur precursor is 0.2-0.3 mmol / mL; and the concentration of zinc chloride in the chlorine precursor is 7-8 mmol / mL.

[0014] Optionally, in step S2 and step S3, the volume ratio of the selenium / sulfur precursor, the zinc precursor and the chlorine precursor is 0.5:0.3-0.5:0.01-0.18.

[0015] Optionally, in step S4, the n-hexane solution of indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dots is purified by purifying indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dots and acetone solution in a volume ratio of 1:10, and then dispersing it into a n-hexane solution.

[0016] Optionally, in step S4, the titanium dioxide / fluorine-doped tin oxide is obtained by preparing a titanium dioxide dense layer and a titanium dioxide electron transport layer on fluorine-doped tin oxide conductive glass.

[0017] An indium zinc selenide sulfur quantum dot material comprising:

[0018] Indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dot material, wherein the indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dot material is used as a photoanode of a photochemical cell.

[0019] A photoelectrochemical cell is made from an indium zinc selenide sulfur quantum dot material and includes: a silver / silver chloride reference electrode containing 2-4 mol / L potassium chloride; an electrolyte composed of 0.2-0.3 mol / L sodium sulfide and 0.3-0.4 mol / L sodium sulfite, wherein the pH value of the electrolyte is 13.

[0020] Beneficial effects of the present invention:

[0021] 1. The present invention synthesizes environmentally friendly indium phosphide colloidal quantum dots. By coating the indium phosphide colloidal quantum dots with a zinc-selenium-sulfur layer rich in zinc vacancies and adopting a surface ligand exchange post-treatment strategy, the indium phosphide colloidal quantum dots are synergistically regulated to improve their photogenerated carrier separation / transfer efficiency, thereby achieving efficient solar photovoltaic conversion efficiency. By replacing the long-chain ligands on the surface of the indium phosphide / zinc-selenium-sulfur-zinc vacancy quantum dots through a series of controllable ligand exchanges, the problems of low photogenerated carrier separation / transfer efficiency and photoelectric conversion efficiency of traditional quantum dots are effectively solved.

[0022] 2. The present invention has strong operability and a simple preparation process. The indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dot material of the present invention has environmentally friendly properties and can effectively separate the electrons and holes generated in the quantum dots under light excitation: first, the zinc vacancies introduced into its zinc selenium sulfur layer structure can effectively capture photogenerated holes; then, surface chlorine ligand exchange can replace the organic long-chain ligands on the surface of the quantum dots, reducing the adverse effects caused by the steric hindrance of the long-chain ligands, thereby further promoting the effective separation / transfer of electrons and holes.

[0023] 3. The preparation method of the present invention can be used to control the indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dots sensitized titanium dioxide / fluorine-doped tin oxide to prepare a photoanode structure. The photoelectrochemical cell prepared by the photoanode structure does not contain any toxic heavy metals, such as lead and cadmium, and is irradiated under 1 standard solar radiation (AM1.5G, 100mW / cm 2 ) with high efficiency saturation photocurrent (11.8mA / cm 2 ), providing a new method to promote future green and environmentally friendly, high-performance quantum dot photoelectrochemical battery systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 This is a scanning electron microscope image of the morphology of an environmentally friendly indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dot of the present invention;

[0026] Figure 2 This is a Fourier infrared image of an environmentally friendly indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dot of the present invention;

[0027] Figure 3 This is a schematic diagram of the structure of an environmentally friendly indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dot sensitized photoanode of the present invention;

[0028] Figure 4 This is a performance diagram of the photoelectrochemical cell of an environmentally friendly indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dot of the present invention. DETAILED DESCRIPTION

[0029] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0030] Example 1

[0031] This embodiment provides an indium zinc selenide sulfur quantum dot material, including:

[0032] Indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dot material, wherein the indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dot material is used as a photoanode of a photochemical cell.

[0033] Example 2

[0034] Based on Example 1, this embodiment provides a method for preparing an indium zinc selenide sulfur quantum dot material, comprising the following steps:

[0035] Step S1: An indium source, a zinc source, and a solvent are sequentially added to a 50 mL three-necked flask, degassed at 130-150° C., then heated to 200° C. under nitrogen protection, a phosphorus source is injected, and the temperature is kept for 1-2 hours to obtain indium phosphide quantum dots;

[0036] The indium source, zinc source and solvent used in the synthesis of phosphide quantum dots are indium chloride, zinc chloride and oleylamine, respectively, wherein the mass (mg) ratio of indium chloride to zinc chloride is 70-80:290-300; the phosphorus source is a mixed solution of tri(dimethylamino)phosphine and oleylamine in a ratio of 1:2, and the amount of indium phosphide quantum dots used is 1 mL.

[0037] Step S2: injecting a zinc precursor and a selenium / sulfur precursor into the indium phosphide quantum dots obtained in step S1 in sequence, heating the mixture to 240° C. and reacting for 30-50 minutes, cooling the mixture to 120° C., and then cooling the mixture to room temperature in a cold water bath reactor to obtain indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots;

[0038] The zinc precursor and selenium / sulfur precursor used in the synthesis of indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots were 2 mmol zinc stearate and 0.5 mmol selenium powder / 0.5 mmol sulfur powder, respectively. The solvents were 10 mL octadecene and 5 mL trioctylphosphine, and the amounts of indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots were 0.3-0.5 mL and 0.5 mL, respectively.

[0039] Step S3: heating the indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots obtained in step S2 to 250-270° C. in an inert gas, then injecting a chlorine precursor and keeping the temperature for 15-30 minutes, cooling the temperature to 120° C. and then cooling the temperature to room temperature in a cold water bath reactor to obtain indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dots;

[0040] The chlorine precursor used in the synthesis of indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dots is 7.5 mmol of zinc chloride, the solvent is 1 mL of ethanol, and the amount used is 0.05-0.3 mL.

[0041] Step S4: immersing titanium dioxide / fluorine-doped tin oxide in a quantum dot / n-hexane solution, and using electrophoretic deposition at a voltage of 150-220 V for 1.5-3 hours to obtain an indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dot material.

[0042] The n-hexane solution of indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dots is obtained by purifying the indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dots and acetone solution in a volume ratio of 1:10, and then dispersing the purified solution into the n-hexane solution.

[0043] Titanium dioxide / fluorine-doped tin oxide is obtained by preparing a titanium dioxide dense layer and a titanium dioxide electron transport layer on fluorine-doped tin oxide conductive glass.

[0044] Conventional electrophoretic deposition involves the deposition of colloidal particles into a material in a stable suspension through the action of a DC electric field. For example, when a DC voltage is applied to an electrophoretic coating, the charged coating particles migrate to the cathode and react with the alkaline solution generated on the cathode surface to form insoluble particles that are deposited on the work surface.

[0045] Example 3

[0046] Based on Example 1 and Example 2, this embodiment provides a photoelectrochemical cell, which is made of indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dot material, including: a photoanode, a platinum counter electrode, a reference electrode and an electrolyte; the photoanode is indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dot material; the platinum counter electrode is a platinum sheet with a purity of 99.99%; the reference electrode is a silver / silver chloride reference electrode with 3 mol / L potassium chloride; the electrolyte is 0.25 mol / L sodium sulfide and 0.35 mol / L sodium sulfite aqueous solution, the pH value of the electrolyte is 13, and the light source is a standard solar irradiation xenon lamp (AM1.5G) with an intensity of 100 mW / cm 2 .

[0047] Indium phosphide / zinc selenide sulfur-zinc vacancy-chlorine passivated quantum dot material is used as the photoanode and assembled with a platinum counter electrode and a silver / silver chloride reference electrode to form a quantum dot photoelectrochemical cell.

[0048] Example 4

[0049] Based on Example 2 and Example 3, specifically, a method for preparing an indium zinc selenide sulfur quantum dot material comprises the following steps:

[0050] S1: Indium phosphide quantum dots were synthesized by hot injection. 70 g of indium chloride and 290 g of zinc chloride were dispersed in 5 mL of oleylamine and degassed at 140°C for 40 min. The mixture was then heated to 200°C under nitrogen and injected with a mixed solution of tri(dimethylamino)phosphine and oleylamine (1:2 by volume). The mixture was reacted for 1 h and quenched in a water bath.

[0051] S2: Inject a zinc precursor (2 mmol zinc stearate dispersed in 10 mL octadecene) and a selenium / sulfur precursor (0.5 mmol selenium powder / 0.5 mmol sulfur powder dispersed in 5 mL trioctylphosphine) into the indium phosphide quantum dots obtained in step S1, heat to 240°C for reaction for 30-50 minutes, cool to 120°C, and then cool the reactor to room temperature in a cold water bath to obtain indium phosphide / zinc selenium sulfur quantum dots; the volume ratio of the selenium precursor to the zinc precursor is 1:1.

[0052] S3: Immerse titanium dioxide / fluorine-doped tin oxide in a quantum dot / n-hexane solution, and use electrophoretic deposition at a voltage of 200 V for 1.5 hours to obtain indium phosphide / zinc selenium sulfur quantum dot material.

[0053] The titanium dioxide / fluorine-doped tin oxide used is obtained by preparing a titanium dioxide dense layer and a titanium dioxide electron transport layer on fluorine-doped tin oxide conductive glass.

[0054] The indium phosphide / zinc selenide sulfur quantum dots used are obtained by purifying the indium phosphide / zinc selenide sulfur quantum dots and an acetone solution in a volume ratio of 1:10 and then dispersing the mixture in a n-hexane solution.

[0055] The photoelectrochemical cell includes: a photoanode, a platinum counter electrode, a reference electrode and an electrolyte; the photoanode is an indium phosphide / zinc selenium sulfur-zinc vacancy quantum dot material, the reference electrode is a silver / silver chloride reference electrode in 3 mol / L potassium chloride; the platinum counter electrode is a platinum sheet with a purity of 99.99%, the electrolyte is an aqueous solution of 0.25 mol / L sodium sulfide and 0.35 mol / L sodium sulfite, and the pH value of the electrolyte is 13.

[0056] Example 5

[0057] Based on Example 2 and Example 3, specifically, a method for preparing an indium zinc selenide sulfur quantum dot material comprises the following steps:

[0058] S1: Indium phosphide quantum dots were synthesized by hot injection. First, 70 g of indium chloride and 290 g of zinc chloride were dispersed in 5 mL of oleylamine and degassed at 140°C for 40 min. Then, the mixture was heated to 200°C under nitrogen and a mixed solution of tris(dimethylamino)phosphine and oleylamine (1:2 by volume) was injected and reacted for 1 h. The mixture was then quenched in a water bath.

[0059] S2: Inject a zinc precursor (2 mmol zinc stearate dispersed in 10 mL octadecene) and a selenium / sulfur precursor (0.5 mmol selenium powder / 0.5 mmol sulfur powder dispersed in 5 mL trioctylphosphine) into the indium phosphide quantum dots obtained in step S1, heat to 240°C for reaction for 30-50 minutes, cool to 120°C, and then cool the reactor to room temperature in a cold water bath to obtain indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots; the volume ratio of the selenium precursor to the zinc precursor is 4:5.

[0060] S3: Immerse titanium dioxide / fluorine-doped tin oxide in a quantum dot / n-hexane solution and use electrophoretic deposition at a voltage of 200 V for 1.5 hours to obtain indium phosphide / zinc selenium sulfur-zinc vacancy quantum dot material.

[0061] The titanium dioxide / fluorine-doped tin oxide used is obtained by preparing a titanium dioxide dense layer and a titanium dioxide electron transport layer on fluorine-doped tin oxide conductive glass.

[0062] The indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots used are obtained by purifying the indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots and an acetone solution in a volume ratio of 1:10, and then dispersing the mixture in a n-hexane solution.

[0063] The photoelectrochemical cell includes: a photoanode, a platinum counter electrode, a reference electrode and an electrolyte; the photoanode is an indium phosphide / zinc selenium sulfur-zinc vacancy quantum dot material; the reference electrode is a silver / silver chloride reference electrode in 3 mol / L potassium chloride; the platinum counter electrode is a platinum sheet with a purity of 99.99%, and the electrolyte is an aqueous solution of 0.25 mol / L sodium sulfide and 0.35 mol / L sodium sulfite, with a pH value of 13.

[0064] Example 6

[0065] Based on Example 2 and Example 3, specifically, a method for preparing an indium zinc selenide sulfur quantum dot material comprises the following steps:

[0066] S1: Indium phosphide quantum dots were synthesized by hot injection. 70 g of indium chloride and 290 g of zinc chloride were dispersed in 5 mL of oleylamine and degassed at 140°C for 40 min. The mixture was then heated to 200°C under nitrogen and injected with a mixed solution of tris(dimethylamino)phosphine and oleylamine (1:2 by volume). The mixture was reacted for 1 h and quenched in a water bath.

[0067] S2: Inject a zinc precursor (2 mmol zinc stearate dispersed in 10 mL octadecene) and a selenium / sulfur precursor (0.5 mmol selenium powder / 0.5 mmol sulfur powder dispersed in 5 mL trioctylphosphine) into the indium phosphide quantum dots obtained in step S1, heat to 240°C for reaction for 30-50 minutes, cool to 120°C, and then cool the reactor to room temperature in a cold water bath to obtain indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots; the volume ratio of the selenium precursor to the zinc precursor is 4:5.

[0068] S3: The indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots obtained in step S2 were heated to 270°C in an inert atmosphere, and then 0.08 mL of a chlorine precursor (7.5 mmol of zinc chloride dispersed in 1 mL of ethanol) was injected and kept warm for 20 minutes. The temperature was then lowered to 120°C and the reactor was cooled to room temperature in a cold water bath to obtain indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dots;

[0069] S4: Immerse titanium dioxide / fluorine-doped tin oxide in a quantum dot / n-hexane solution and use electrophoretic deposition at a voltage of 200 V for 3 hours to obtain an indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dot material.

[0070] The titanium dioxide / fluorine-doped tin oxide used is obtained by preparing a titanium dioxide dense layer and a titanium dioxide electron transport layer on fluorine-doped tin oxide conductive glass.

[0071] The indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots used are obtained by purifying the indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots and an acetone solution in a volume ratio of 1:10, and then dispersing the mixture in a n-hexane solution.

[0072] The photoelectrochemical cell includes: a photoanode, a platinum counter electrode, a reference electrode and an electrolyte; the photoanode is an indium phosphide / zinc selenium sulfur-zinc vacancy quantum dot material; the reference electrode is a silver / silver chloride reference electrode in 3 mol / L potassium chloride; the platinum counter electrode is a platinum sheet with a purity of 99.99%, and the electrolyte is an aqueous solution of 0.25 mol / L sodium sulfide and 0.35 mol / L sodium sulfite, with a pH value of 13.

[0073] Example 7

[0074] Based on Example 2 and Example 3, specifically, a method for preparing an indium zinc selenide sulfur quantum dot material comprises the following steps:

[0075] S1: Indium phosphide quantum dots were synthesized by hot injection. 70 g of indium chloride and 290 g of zinc chloride were dispersed in 5 mL of oleylamine and degassed at 140°C for 40 min. The mixture was then heated to 200°C under nitrogen and injected with a mixed solution of tris(dimethylamino)phosphine and oleylamine (1:2 by volume). The mixture was reacted for 1 h and quenched in a water bath.

[0076] S2: Inject a zinc precursor (2 mol zinc stearate dispersed in 10 mL octadecene) and a selenium / sulfur precursor (0.5 mmol selenium powder / 0.5 mmol sulfur powder dispersed in 5 mL trioctylphosphine) into the indium phosphide quantum dots obtained in step S1, heat to 240°C for reaction for 30-50 minutes, cool to 120°C, and then cool the reactor to room temperature in a cold water bath to obtain indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots; the volume ratio of the selenium precursor to the zinc precursor is 4:5.

[0077] S3: The indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots obtained in step S2 were heated to 270°C in an inert atmosphere, and then 0.16 mL of a chlorine precursor (7.5 mmol of zinc chloride dispersed in 1 mL of ethanol) was injected and kept warm for 20 minutes. The temperature was then lowered to 120°C and the reactor was cooled to room temperature in a cold water bath to obtain indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dots;

[0078] S4: Immerse titanium dioxide / fluorine-doped tin oxide in a quantum dot / n-hexane solution and use electrophoretic deposition at a voltage of 200 V for 3 hours to obtain an indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dot material.

[0079] The titanium dioxide / fluorine-doped tin oxide used is obtained by preparing a titanium dioxide dense layer and a titanium dioxide electron transport layer on fluorine-doped tin oxide conductive glass.

[0080] The indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots used are obtained by purifying the indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots and an acetone solution in a volume ratio of 1:10, and then dispersing the mixture in a n-hexane solution.

[0081] The photoelectrochemical cell includes: a photoanode, a platinum counter electrode, a reference electrode and an electrolyte; the photoanode is an indium phosphide / zinc selenium sulfur-zinc vacancy quantum dot material; the reference electrode is a silver / silver chloride reference electrode in 3 mol / L potassium chloride; the platinum counter electrode is a platinum sheet with a purity of 99.99%, and the electrolyte is an aqueous solution of 0.25 mol / L sodium sulfide and 0.35 mol / L sodium sulfite, with a pH value of 13.

[0082] Example 8

[0083] Based on Example 2 and Example 3, specifically, a method for preparing an indium zinc selenide sulfur quantum dot material comprises the following steps:

[0084] S1: Indium phosphide quantum dots were synthesized by hot injection. 70 g of indium chloride and 290 g of zinc chloride were dispersed in 5 mL of oleylamine and degassed at 140°C for 40 min. The mixture was then heated to 200°C under nitrogen and injected with a mixed solution of tris(dimethylamino)phosphine and oleylamine (1:2 by volume). The mixture was reacted for 1 h and quenched in a water bath.

[0085] S2: Inject a zinc precursor (2 mmol zinc stearate dispersed in 10 mL octadecene) and a selenium / sulfur precursor (0.5 mmol selenium powder / 0.5 mmol sulfur powder dispersed in 5 mL trioctylphosphine) into the indium phosphide quantum dots obtained in step S1, heat to 240°C for reaction for 30-50 minutes, cool to 120°C, and then cool the reactor to room temperature in a cold water bath to obtain indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots; the volume ratio of the selenium precursor to the zinc precursor is 4:5.

[0086] S3: The indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots obtained in step S2 were heated to 270°C in an inert atmosphere, and then 0.18 mL of a chlorine precursor (7.5 mmol of zinc chloride dispersed in 1 mL of ethanol) was injected and kept warm for 20 minutes. The temperature was then lowered to 120°C and the reactor was cooled to room temperature in a cold water bath to obtain indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dots;

[0087] S4: Immerse titanium dioxide / fluorine-doped tin oxide in a quantum dot / n-hexane solution and use electrophoretic deposition at a voltage of 200 V for 3 hours to obtain an indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dot material.

[0088] The titanium dioxide / fluorine-doped tin oxide used is obtained by preparing a titanium dioxide dense layer and a titanium dioxide electron transport layer on fluorine-doped tin oxide conductive glass.

[0089] The indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots used are obtained by purifying the indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots and an acetone solution in a volume ratio of 1:10, and then dispersing the mixture in a n-hexane solution.

[0090] The photoelectrochemical cell includes: a photoanode, a platinum counter electrode, a reference electrode and an electrolyte; the photoanode is an indium phosphide / zinc selenium sulfur-zinc vacancy quantum dot material; the reference electrode is a silver / silver chloride reference electrode in 3 mol / L potassium chloride; the platinum counter electrode is a platinum sheet with a purity of 99.99%; the electrolyte is an aqueous solution of 0.25 mol / L sodium sulfide and 0.35 mol / L sodium sulfite, with a pH value of 13.

[0091] Example 9

[0092] The morphology of the indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dots prepared in Example 7 was analyzed, and the transmission electron microscope analysis showed that Figure 1 The Fourier transform infrared spectra of InP / ZnSeS-ZnVacancy-Cl2 passivated quantum dots in n-hexane were analyzed. Figure 2 .Depend on Figure 1 and Figure 2 It can be seen that the indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dots of the present invention introduce zinc vacancies into the zinc selenium sulfur layer, and then the chlorine precursor replaces the long-chain ligands on the surface.

[0093] from Figure 3 It can be seen that the introduction of zinc vacancies effectively captures photogenerated holes and promotes carrier separation. The surface chlorine precursor exchange strategy further optimizes the performance of quantum dots by replacing long-chain ligands, reducing steric hindrance, and significantly improving the separation efficiency of electrons and holes. This design, combining defect engineering (zinc vacancies) with ligand engineering (chlorine precursor exchange), has substantial advantages in the field of quantum dot surface optimization.

[0094] Figure 4 The performance of quantum dot photoelectrochemical cells under various conditions, including saturation photocurrent density, was demonstrated. The performance data demonstrates that the introduction of zinc vacancies and a surface chlorine precursor exchange strategy significantly improves the cell's saturation photocurrent density. Compared to traditional quantum dot photoelectrochemical cells, this effectively addresses the low photoelectric conversion efficiency of conventional cells and holds significant significance in the field of solar photovoltaic conversion.

[0095] Example 10

[0096] For the above examples 4 to 8, a standard solar simulator (AM1.5G) was used as the light source with an intensity of 100 mW / cm 2 , 0.25M sodium sulfide / 0.35M sodium sulfite solution was used as the electrolyte, the pH value was 13, and a photoelectrochemical cell was constructed. The properties of the quantum dots prepared by the present invention and the photoelectrochemical cell thereof were tested. The results are shown in Table 1:

[0097] Table 1 / Photoelectrochemical cell performance test results parameter table

[0098]

[0099] As can be seen from the above table, the novel environmentally friendly quantum dots of the present invention have excellent photoelectric conversion properties. Under the synergistic effect of introducing zinc vacancies and surface ligand exchange, the photocurrent is increased by about 2.1 times.

[0100] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope of the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for preparing indium zinc selenide sulfur quantum dot material, characterized in that: The following steps are involved: Step S1: An indium source, a zinc source, and a solvent are sequentially added to a 50 mL three-necked flask, degassed at 130-150° C., then heated to 200° C. under nitrogen protection, a phosphorus source is injected, and the temperature is kept for 1-2 hours to obtain indium phosphide quantum dots; Step S2: injecting a zinc precursor and a selenium / sulfur precursor into the indium phosphide quantum dots obtained in step S1 in sequence, heating the mixture to 240° C. and reacting for 30-50 minutes, cooling the mixture to 120° C., and then cooling the mixture to room temperature in a cold water bath reactor to obtain indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots; Step S3: heating the indium phosphide / zinc selenium sulfur-zinc vacancy quantum dots obtained in step S2 to 250-270° C. in an inert gas, then injecting a chlorine precursor and keeping the temperature for 15-30 minutes, cooling the temperature to 120° C. and then cooling the temperature to room temperature in a cold water bath reactor to obtain indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dots; Step S4: immersing titanium dioxide / fluorine-doped tin oxide in a quantum dot / n-hexane solution, and using electrophoretic deposition at a voltage of 150-220 V for 1.5-3 hours to obtain an indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dot material.

2. The method for preparing an indium zinc selenide sulfur quantum dot material according to claim 1, wherein: In step S1, the indium source, the zinc source, and the solvent used are indium chloride, zinc chloride, and oleylamine, respectively; the phosphorus source is a mixed solution of tri(dimethylamino)phosphine and oleylamine; when the oleylamine is added for the first time, the mass volume ratio of the indium chloride to the oleylamine is 70-80:5-10; and in the mixed solution of triphosphine and oleylamine, the volume ratio of the mixed solution of tri(dimethylamino)phosphine and oleylamine is 1:

2.

3. The method for preparing an indium zinc selenide sulfur quantum dot material according to claim 1, characterized in that: In the step S2 and the step S3, zinc stearate is dispersed in 1-octadecene to obtain a zinc precursor; selenium powder and sulfur powder are dispersed in trioctylphosphine to obtain a selenium / sulfur precursor; Disperse zinc chloride in ethanol to obtain a chlorine precursor.

4. The method for preparing an indium zinc selenide sulfur quantum dot material according to any one of claims 1 or 3, characterized in that: In step S2 and step S3, the concentration of zinc stearate in the zinc precursor is 0.2-0.3 mmol / mL; the concentration of selenium powder / sulfur powder in the selenium / sulfur precursor is 0.2-0.3 mmol / mL; and the concentration of zinc chloride in the chlorine precursor is 7-8 mmol / mL.

5. The method for preparing an indium zinc selenide sulfur quantum dot material according to claim 1, characterized in that: In the step S2 and the step S3, the volume ratio of the selenium / sulfur precursor, the zinc precursor and the chlorine precursor is 0.5:0.3-0.5:0.01-0.

18.

6. The method for preparing an indium zinc selenide sulfur quantum dot material according to claim 1, characterized in that: In step S4, the n-hexane solution of the indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dots is purified by mixing the indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dots with an acetone solution in a volume ratio of 1:10, and then dispersing the solution into a n-hexane solution.

7. The method for preparing an indium zinc selenide sulfur quantum dot material according to claim 1, characterized in that: In the step S4, the titanium dioxide / fluorine-doped tin oxide is obtained by preparing a titanium dioxide dense layer and a titanium dioxide electron transport layer on the fluorine-doped tin oxide conductive glass.

8. An indium zinc selenide sulfur quantum dot material, obtained by the method for preparing an indium zinc selenide sulfur quantum dot material according to any one of claims 1 to 7, characterized in that: include: Indium phosphide / zinc selenide sulfur-zinc vacancy-chlorine passivated quantum dot materials.

9. The indium zinc selenide sulfur quantum dot material according to claim 8, characterized in that: The indium phosphide / zinc selenium sulfur-zinc vacancy-chlorine passivated quantum dot material is used as a photoanode of a photochemical cell.

10. A photoelectrochemical cell, made from the indium zinc selenide sulfur quantum dot material according to claim 8, characterized in that: include: Silver / silver chloride reference electrode containing 2-4 mol / L potassium chloride; The electrolyte is composed of 0.2-0.3 mol / L sodium sulfide and 0.3-0.4 mol / L sodium sulfite, and the pH value of the electrolyte is 13.

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