Infrared electrochemical cell based on tellurium-based quantum dots and preparation method thereof

Abstract

The invention discloses an infrared electrochemical cell based on tellurium-based quantum dots and a preparation method thereof, and belongs to the field of photoelectrochemical cells, the method comprises the following steps: mixing a first solvent system to form a copper-indium solution, mixing a second solvent system to form a tellurium solution, dropwise adding the tellurium solution into the copper-indium solution, and reacting to obtain the tellurium-based quantum dots. A copper-indium-tellurium quantum dot solution is obtained; adding the copper-indium-tellurium quantum dot solution into a third solvent system containing a zinc source, and reacting to coat the surfaces of the copper-indium-tellurium quantum dots of the copper-indium-tellurium quantum dot solution to form a zinc telluride shell so as to prepare the copper-indium-tellurium core-shell quantum dots; and depositing the copper-indium-tellurium core-shell quantum dots on a porous bismuth vanadate electrode in an electrophoretic deposition manner. The preparation method is simple, and large-scale synthesis and device construction are easy.

Description

Technical Field

[0001] This invention relates to the field of photoelectrochemical cell technology, and in particular to an infrared photoelectrochemical cell based on tellurium quantum dots and its preparation method. Background Technology

[0002] Photoelectrochemical cell technology, as a cutting-edge energy conversion technology, can directly convert solar energy into chemical energy (such as hydrogen energy). Its core structure includes a photosensitive electrode, an electrolyte, and external circuitry. This technology boasts significant advantages such as high integration, excellent energy conversion efficiency, and low manufacturing cost. Furthermore, compared to the stepwise hydrogen production system of photovoltaic power generation followed by water electrolysis, this technology is more cost-competitive due to the elimination of the power conversion stage. However, current photoelectrochemical cell technology still faces multiple bottlenecks restricting its industrial application. These include limitations in material performance, with photoelectrodes generally exhibiting insufficient photocatalytic activity and poor chemical stability. Additionally, it relies on strongly acidic or alkaline environments, requiring the addition of large amounts of hole scavengers (sacrificial agents) to suppress photogenerated hole recombination.

[0003] Quantum dot materials, due to their tunable bandgap and broad-spectrum absorption characteristics, are considered key materials for improving the performance of photoelectrochemical cells. However, traditional quantum dots (such as lead / cadmium-based systems) contain toxic heavy metal components, which contradicts the trend of green manufacturing. Existing quantum dot photoelectrodes, such as the manganese alloyed silver indium sulfide quantum dots involved in patent CN115353882A and most quantum dot systems, typically absorb ultraviolet-visible light. Limited by the material's band structure and synthesis process, they lack the ability to absorb infrared light, which accounts for nearly 50% of the solar spectrum. Furthermore, the valence band level of titanium dioxide, a material commonly used for quantum dot-loaded photoelectrodes, is not conducive to matching the water oxidation interface reaction, resulting in a low overall light energy utilization rate for existing quantum dot photoelectrochemical cells. Therefore, developing environmentally friendly infrared-responsive quantum dot materials and constructing novel photoelectrodes and photoelectrochemical cell devices based on them is urgently needed to overcome existing technological bottlenecks and expand clean energy application scenarios. Summary of the Invention

[0004] One of the objectives of this invention is to provide an infrared photoelectrochemical cell based on tellurium quantum dots and its preparation method, in order to solve the problems of weak utilization of infrared light by quantum dot photoelectrodes, mismatch of valence band energy levels in interfacial reactions, and the need for additional sacrificial agents in existing photoelectrochemical cells.

[0005] This invention is achieved through the following technical solution: a method for preparing a photoelectrode based on tellurium quantum dots, comprising the following steps: a) providing a copper source, an indium source, and a first solvent system, mixing them to form a copper-indium solution; providing a tellurium source and a second solvent system, mixing them to form a tellurium solution; and adding the tellurium solution dropwise to the copper-indium solution at a temperature of 240-260°C for 4-6 minutes to obtain a copper-indium tellurium quantum dot solution; b) adding the copper-indium tellurium quantum dot solution to a third solvent system containing a zinc source, reacting at a temperature of 155-165°C for 8-12 minutes to coat the surface of the copper-indium tellurium quantum dots in the copper-indium tellurium quantum dot solution with a zinc telluride shell to prepare copper-indium tellurium core-shell quantum dots; c) depositing the copper-indium tellurium core-shell quantum dots on a porous bismuth vanadate electrode by electrophoretic deposition at a voltage of 140-160V for 1-3 hours.

[0006] Furthermore, the first solvent system comprises dodecyl mercaptan, n-octadecene, and oleylamine in a volume ratio of 6:3:1~3; the second solvent system comprises tri-n-octylphosphine and n-octadecene in a volume ratio of 1:5.

[0007] Further, in step a), the copper-indium solution is preheated to 250°C, and after the tellurium solution is added dropwise, the reaction is kept at this temperature for 5 minutes.

[0008] Further, in step b), the third solvent system containing the zinc source is prepared by dissolving oleic acid and zinc acetate in n-octadecene.

[0009] Furthermore, in step b), the reaction is carried out at 160°C for 10 min.

[0010] Further, in step c), the electrophoretic deposition voltage is 150V and the time is 2 hours.

[0011] Another aspect of the present invention provides a tellurium-based quantum dot-based photoelectrode comprising: a porous bismuth vanadate electrode substrate; and a copper indium tellurium core-shell quantum dot layer as described above deposited on the porous bismuth vanadate electrode substrate.

[0012] Furthermore, the copper indium tellurium core-shell quantum dots are monodisperse particles.

[0013] The present invention also provides an infrared photoelectrochemical cell based on tellurium quantum dots, comprising: a photoelectrode based on tellurium quantum dots as described above, serving as a photoanode; a counter electrode; and an electrolyte.

[0014] Furthermore, the counter electrode is a platinum sheet electrode.

[0015] Furthermore, the electrolyte is a 5 mol / L potassium borate aqueous solution with a pH of 9.0.

[0016] Furthermore, the photoelectrode based on tellurium quantum dots may also include a reference electrode; the reference electrode is an Ag / AgCl reference electrode immersed in a saturated potassium chloride solution.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0018] 1. The preparation method of this invention is simple and easy to synthesize on a large scale and construct devices. This invention uses tellurium-based quantum dots with infrared absorption band coverage as photosensitive materials, which can effectively capture the infrared band energy of sunlight. The photoelectrochemical cell constructed by the obtained photoelectrode has obvious performance advantages and its absorption efficiency of sunlight energy is greatly improved compared with traditional quantum dot photoelectrodes.

[0019] 2. This invention selects bismuth vanadate as the load photoelectrode to meet the valence band energy level of the matching interface reaction. It can promote the water oxidation reaction without adding a hole sacrificial agent. Furthermore, the electrolyte is a sodium borate solution with a pH of 9.0, which avoids the use of a strongly alkaline high-concentration sodium sulfide solution, reduces the cost of the device, and solves the problem of the need for a hole sacrificial agent in quantum dot photoelectrodes. Attached Figure Description

[0020] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0021] Figure 1 This is a schematic diagram of the photoelectrode structure based on tellurium quantum dots provided in Embodiment 1 of the present invention.

[0022] Figure 2 This is a scanning electron microscope image of a photoelectrode based on tellurium quantum dots provided in Embodiment 1 of the present invention.

[0023] Figure 3 This is a transmission electron microscope (TEM) scan image of tellurium-based quantum dots provided in Embodiment 1 of the present invention.

[0024] Figure 4 This is a physical image of an infrared photoelectrochemical cell based on tellurium quantum dots provided in Embodiment 1 of the present invention.

[0025] Figure 5 The spectral absorption curves of the colloidal quantum dots prepared by the steps in Examples 1 and 2 are provided as comparative examples of the present invention.

[0026] Figure 6 The photocurrent test diagram of the tellurium-based quantum dot infrared photoelectrochemical cell prepared by the steps in Example 1 and Example 2 is provided as a comparative example of the present invention.

[0027] In the above figures, the reference numerals represent: 111, tellurium-based quantum dot; 112, bismuth vanadate electrode; 113, conductive layer; 114, transparent glass layer; 11, tellurium-based quantum dot photoelectrode; 12, platinum sheet electrode; 13, reference electrode; 14, electrolyte. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail. The terms “comprising,” “including,” “having,” “containing,” etc., as used herein are open-ended terms meaning to include but not limited to. Unless the context clearly indicates otherwise, the expressions “a” and “an” as used herein include plural references. The term “about” as used herein indicates a range of ±20% of the following numerical value. In some embodiments, the term “about” indicates a range of ±10% of the following numerical value. In some embodiments, the term “about” indicates a range of ±5% of the following numerical value.

[0030] Example 1

[0031] This embodiment discloses a quantum dot infrared photoelectrochemical cell, which is prepared through the following steps:

[0032] Step 1: Synthesis of copper indium tellurium quantum dots. First, accurately weigh 1 mmol of cuprous iodide, 1 mmol of indium acetate, 6 mL of dodecyl mercaptan, 3 mL of n-octadecene, and 2 mL of oleylamine into a 50 mL three-necked flask. Degas the mixture under vacuum at 60 °C for 30 minutes, then heat it to 120 °C under a nitrogen atmosphere and maintain the temperature for 10 minutes to ensure complete dissolution of the raw materials, forming a copper indium solution. Simultaneously, accurately weigh 1 mL of tri-n-octylphosphine and 5 mL of oleylamine to dissolve 6 mmol of tellurium powder to prepare a tellurium solution. Then heat the copper indium solution to 250 °C, and slowly add the tellurium solution dropwise into the copper indium solution using a syringe. After the addition is complete, maintain the temperature for 5 minutes to obtain a copper indium tellurium quantum dot solution. Finally, quench the reaction in a cold water bath using the three-necked flask, and transfer the reaction liquid to a centrifuge tube for collection and storage at 4 °C.

[0033] Step 2: Synthesis of zinc telluride-coated copper indium telluride core-shell quantum dots. First, accurately weigh 2 mmol of oleic acid, 200 mg of zinc acetate, and 10 mL of octadecene into a 50 mL three-necked flask. Degas the mixture under vacuum at 90 °C for 30 minutes, then heat it to 160 °C under a nitrogen atmosphere and maintain the temperature for 30 minutes to ensure complete dissolution of the raw materials, thus obtaining a zinc oleate solution. Using a syringe, slowly add 10 mL of the copper indium telluride quantum dot solution dropwise into the prepared zinc oleate solution. After the addition is complete, maintain the temperature at 160 °C for 10 minutes. Finally, quench the reaction in a cold water bath using the three-necked flask, and transfer the reaction liquid to a centrifuge tube for collection and storage in a 4 °C refrigerator.

[0034] Step 3: Fabrication of tellurium-based quantum dot photoelectrode. A porous bismuth vanadate electrode was used as the working electrode, and FTO glass as the counter electrode. A two-electrode electrophoresis apparatus was constructed using a toluene solution containing copper indium telluride core-shell quantum dots coated with zinc telluride as the electrophoretic deposition solution. Deposition was carried out continuously at a stable voltage of 150V for 2 hours to obtain a tellurium-based quantum dot photoelectrode, the structure of which is shown below. Figure 1 As shown, it includes tellurium-based quantum dots, bismuth vanadate electrodes, a conductive layer, and a transparent glass layer. Its structure was observed using a scanning electron microscope, as follows: Figure 2 The diagram shows a clear delamination of the bismuth vanadate electrode, conductive layer, and transparent glass layer, but this is not observable due to the small size of the quantum dots (approximately 10 nanometers). Figure 3 The transmission electron microscope image shown indicates that the tellurium-based quantum dots are monodisperse particles.

[0035] Step 4: Finally, construct the infrared photoelectrochemical cell. The photoanode is the tellurium-based quantum dot photoelectrode prepared by the above method, the counter electrode is a platinum sheet electrode, the reference electrode is an Ag / AgCl reference electrode immersed in a saturated potassium chloride solution, and the electrolyte is a 5 mol / L potassium borate aqueous solution with a pH of 9.0. Figure 4The image shown is a physical diagram of the tellurium-based quantum dot infrared photoelectrochemical cell in Example 1 of the present invention, which includes a tellurium-based quantum dot photoelectrode, a platinum sheet electrode, a reference electrode, and an electrolyte.

[0036] Figure 1 This diagram shows a schematic of the photoelectrode structure based on tellurium quantum dots prepared in this embodiment. Figure 1 It includes, from top to bottom, a tellurium-based quantum dot layer 111, a bismuth vanadate electrode layer 112, a conductive layer 113, and a transparent glass layer 114. Figure 2 The image shown is a scanning electron microscope (SEM) image of the tellurium-based quantum dot-based photoelectrode prepared in this embodiment. Figure 3 This is a transmission electron microscope (TEM) scan image of the tellurium-based quantum dots prepared in this embodiment. Figure 4 The diagram shows a physical image of the infrared photoelectrochemical cell based on tellurium quantum dots prepared in this embodiment, including a tellurium quantum dot photoelectrode 11, a platinum sheet electrode 12, a reference electrode 13, and an electrolyte 14.

[0037] Example 2

[0038] A quantum dot infrared photoelectrochemical cell is prepared by the following steps:

[0039] Step 1: Synthesis of copper indium tellurium quantum dots. First, accurately weigh 1 mmol of cuprous iodide, 1 mmol of indium acetate, 6 mL of dodecyl mercaptan, 3 mL of n-octadecene, and 2 mL of oleylamine into a 50 mL three-necked flask. Degas the mixture under vacuum at 60 °C for 30 minutes, then heat it to 120 °C under a nitrogen atmosphere and maintain the temperature for 10 minutes to ensure complete dissolution of the raw materials, forming a copper indium solution. Simultaneously, accurately weigh 1 mL of tri-n-octylphosphine and 5 mL of oleylamine to dissolve 6 mmol of tellurium powder to prepare a tellurium solution. Then heat the copper indium solution to 250 °C, and slowly add the tellurium solution dropwise into the copper indium solution using a syringe. After the addition is complete, maintain the temperature for 5 minutes to obtain a copper indium tellurium quantum dot solution. Finally, quench the reaction in a cold water bath using the three-necked flask, and transfer the reaction liquid to a centrifuge tube for collection and storage at 4 °C.

[0040] Step 2: Fabrication of tellurium-based quantum dot photoelectrode. A porous bismuth vanadate electrode was used as the working electrode and FTO glass as the counter electrode. A two-electrode electrophoresis apparatus was constructed using a toluene solution containing dissolved copper indium tellurium quantum dots as the electrophoretic deposition solution. Deposition was carried out continuously at a stable voltage of 150V for 2 hours to obtain a tellurium-based quantum dot photoelectrode.

[0041] Step 3: Finally, construct the infrared photoelectrochemical cell. The photoanode is the tellurium-based quantum dot photoelectrode prepared by the above method, the counter electrode is a platinum sheet electrode, the reference electrode is an Ag / AgCl reference electrode immersed in a saturated potassium chloride solution, and the electrolyte is a 5 mol / L potassium borate aqueous solution with a pH of 9.0.

[0042] Comparative Example

[0043] In this comparative example, the comparison is made with the photoelectrochemical cell prepared by the method described in publication number CN115353882A, published on November 18, 2022, entitled "A Manganese Alloyed Silver Indium Sulfide / Copper Doped Zinc Sulfide Quantum Dot Material and Its Preparation Method and Application".

[0044] Photoelectrochemical cells were prepared according to Examples 1 and 2 and the method disclosed in CN115353882A. The performance of the prepared quantum dot photoelectrochemical cells was tested using a source meter and a standard AM1.5G solar simulator. The results and device parameters are shown in Table 1.

[0045] Table 1. Performance Test Results of Quantum Dot Photoelectrochemical Cells

[0046]

[0047] As shown in the table above, the infrared photoelectrochemical cell based on tellurium quantum dots in this invention has excellent solar photocurrent density. The quantum dot photoelectrochemical cell with zinc telluride shell passivation in Example 1 of this application has a saturation photocurrent density of 6.9 mA / cm2, while the photoelectrochemical cell with copper indium tellurium quantum dots in Example 2 has a saturation photocurrent density of 4.3 mA / cm2. This result shows that telluride passivation shell helps to improve the photocurrent activity of copper indium tellurium quantum dots. Figure 5 The absorption curves of the colloidal quantum dots provided in Examples 1 and 2 of this application show that both types of quantum dots can absorb infrared light with a wavelength of up to 900 nm, thereby utilizing the energy of infrared light to drive photoelectrochemical reactions. Furthermore, the quantum dots in Example 1, passivated with a zinc telluride shell, exhibit stronger absorption intensity, indicating that the zinc telluride shell can modulate the energy levels of the quantum dots. Figure 6 The current density-voltage curves of the infrared photoelectrochemical cells in Examples 1 and 2 of this application under light-switched conditions are shown. It can be observed that the quantum dot photoelectrochemical cell passivated with a zinc telluride shell exhibits a higher saturation photocurrent density. Comparing the performance test results of the quantum dot photoelectrochemical cells shown in Table 1, it can be seen that the tellurium-based quantum dot infrared photoelectrochemical cell provided in this invention possesses excellent photoelectric performance and does not require the addition of an additional sacrificial agent, thus reducing the overall cost of the device.

[0048] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a tellurium-based quantum dot-based photoelectrode, characterized by, The preparation method comprises: a) providing a copper source, an indium source and a first solvent system, mixing to form a copper-indium solution, providing a tellurium source and a second solvent system, mixing to form a tellurium solution, and adding the tellurium solution dropwise into the copper-indium solution at a temperature of 240-260℃ for 4-6 min to obtain a copper-indium-tellurium quantum dot solution; b) adding the copper-indium-tellurium quantum dot solution into a third solvent system containing a zinc source, and reacting at a temperature of 155-165℃ for 8-12 min, forming a zinc telluride shell on the surface of the copper-indium-tellurium quantum dots in the copper-indium-tellurium quantum dot solution to prepare copper-indium-tellurium core-shell quantum dots; c) depositing the copper-indium-tellurium core-shell quantum dots on a porous bismuth vanadate electrode by electrophoretic deposition, the voltage for electrophoretic deposition being 140-160V and the time being 1-3h.

2. The method for preparing a tellurium-based quantum dot-based photoelectrode according to claim 1, characterized by, The first solvent system comprises dodecanethiol, n-octadecene and oleylamine, and the volume ratio is 6:3:1-3; The second solvent system comprises tri-n-octylphosphine and n-octadecene, and the volume ratio is 1:

5.

3. The method for producing a tellurium-based quantum dot-based photoelectrode according to claim 1 or 2, characterized by, In step a), the copper-indium solution is preheated to 250℃, and after the addition of the tellurium solution is completed, the reaction is maintained for 5 min.

4. The method for producing a tellurium-based quantum dot-based photoelectrode according to any one of claims 1 to 3, characterized by, In step b), the third solvent system containing a zinc source is prepared by dissolving oleic acid and zinc acetate in n-octadecene.

5. The method for preparing a tellurium-based quantum dot-based photoelectrode according to any one of claims 1 to 3, characterized by, In step b), the reaction is carried out at a temperature of 160℃ for 10 min.

6. The method for preparing a tellurium-based quantum dot-based photoelectrode according to any one of claims 1 to 5, characterized by, In step c), the voltage for electrophoretic deposition is 150V, and the time is 2h.

7. A tellurium-based quantum dot-based photoelectrode, characterized by, It comprises: a porous bismuth vanadate electrode substrate; and a layer of copper-indium-tellurium core-shell quantum dots as claimed in any one of claims 1-6 deposited on the porous bismuth vanadate electrode substrate.

8. The method for preparing a tellurium-based quantum dot-based photoelectrode according to claim 1, characterized by, The copper-indium-tellurium core-shell quantum dots are monodisperse particles.

9. A tellurium-based quantum dot-based infrared photoelectrochemical cell, characterized by, It comprises: a tellurium-based quantum dot-based photoelectrode as claimed in claim 7 or 8 as a photoanode; a counter electrode; and an electrolyte.

10. The infrared photoelectrochemical cell of claim 9, wherein, The counter electrode is a platinum sheet electrode; The electrolyte is a potassium borate aqueous solution with a pH value of 9.0.

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