A light-driven carbon dioxide reduction system based on water-soluble copper-rich defect quantum dots

Abstract

The present invention discloses a light-driven carbon dioxide reduction system based on water-soluble copper-rich defect quantum dots, relating to the technical field of light-driven carbon dioxide reduction to fuel production. The system comprises a stoppered quartz bottle containing water-soluble copper-rich defect quantum dots, deionized water, and ascorbic acid. The light-driven carbon dioxide reduction to fuel production system of the present invention does not require the addition of a stirring process under actual working conditions. More importantly, the system can produce carbon monoxide with high selectivity. The present invention solves the problem that the activity and stability of existing photocatalysts are relatively low and that stirring is required under actual working conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of light-driven reduction of carbon dioxide to produce fuel, and in particular to a light-driven reduction of carbon dioxide system based on water-soluble copper-rich defect quantum dots. Background Art

[0002] Photocatalytic CO2 production for sustainable fuels is a novel technology that directly utilizes sunlight energy, coupled with CO2 emission reduction, to convert it into carbon-containing fuel molecules (such as carbon monoxide and methane). This technology typically consists of a catalytically active photocatalyst, a solvent that facilitates CO2 dissolution, and an external reaction device. Its simple structure offers lower device costs than technologies that generate electricity through photovoltaics followed by electrolysis of CO2 in an electrolyzer. Currently, large-scale practical applications of photocatalytic CO2 production for sustainable fuels are hindered by several key limitations: First, the activity and stability of the photocatalysts are relatively low. Second, most experimental demonstrations of this technology have been conducted using simulated indoor sunlight, which differs from natural outdoor sunlight due to factors such as cloud cover and diurnal temperature fluctuations. Third, many photocatalysts currently absorb light energy by maintaining a suspension in a continuously stirred state, hindering the development of this technology from an energy-saving perspective. Quantum dots, on the other hand, can maintain a stable dispersed phase in a colloidal aqueous solution, reducing sedimentation during the reaction and eliminating the need for stirring, thus facilitating energy conservation. Summary of the Invention

[0003] In order to solve the above technical problems, the purpose of the present invention is to provide a light-driven carbon dioxide reduction system based on water-soluble copper-rich defect quantum dots to solve the problems of low activity and stability of existing photocatalysts and the need for stirring in actual working conditions.

[0004] The technical solution of the present invention to solve the above technical problems is as follows: a light-driven carbon dioxide reduction system based on water-soluble copper-rich defect quantum dots is provided, which includes a stoppered quartz bottle containing water-soluble copper-rich defect quantum dots, deionized water and ascorbic acid.

[0005] The beneficial effects of the present invention are as follows: the light-driven reduction of carbon dioxide to fuel system of the present invention does not require the addition of a stirring process under actual working conditions. The system does not undergo sedimentation of quantum dots under natural light irradiation for up to 28 days, reflecting the superiority of the stable colloidal dispersed phase. More importantly, the system converts carbon dioxide to produce carbon monoxide with high selectivity, achieving a generation rate of 0.4 millimoles per gram per hour, and maintaining excellent stability within 360 hours of continuous illumination, surpassing the performance of most light-driven reduction of carbon dioxide to produce carbon monoxide systems in the world. When the capacity (volume) of the stoppered quartz bottle increases, the corresponding amount of water-soluble copper-defect-rich quantum dots, deionized water and ascorbic acid should also be increased accordingly to be able to sufficiently reduce more carbon dioxide.

[0006] On the basis of the above technical solution, the present invention can also be improved as follows:

[0007] Furthermore, the volume mass ratio of the stoppered quartz bottle, the water-soluble copper-defect-rich quantum dots, deionized water and ascorbic acid is 45-55 mL: 0.18-0.21 mg: 4-6 mL: 80-90 mg.

[0008] Furthermore, the volume mass ratio of the stoppered quartz bottle, the water-soluble copper-rich defect quantum dots, deionized water and ascorbic acid is 50 mL: 0.2 mg: 5 mL: 88 mg.

[0009] Furthermore, water-soluble copper-rich defect quantum dots were prepared by the following method:

[0010] (1) dissolving sulfur powder with oleylamine to prepare a sulfur solution;

[0011] (2) mixing cuprous iodide, zinc acetate, indium acetate, dodecanethiol, and oleylamine, degassing, and heating to prepare a copper indium zinc solution;

[0012] (3) heating the copper indium zinc solution obtained in step (2) at 200-250°C for 8-12 minutes, adding the sulfur solution obtained in step (1) dropwise, heating at 180-220°C for 18-22 minutes, and quenching in cold water to obtain a WU-V Cu -CuInS2 reaction mother solution, i.e., reaction mother solution containing water-insoluble copper-defect-rich quantum dots;

[0013] (4) mercaptopropionic acid and dimethylformamide were mixed, and the reaction mother solution prepared in step (3) was added, degassed, heated, quenched in cold water, and then precipitated with n-propanol, and the resulting precipitate was dissolved in deionized water to obtain WS-V Cu -CuInS2 solution, that is, a water-soluble copper-defect-rich quantum dot solution.

[0014] Furthermore, in step (1), the molar volume ratio of sulfur powder to oleylamine is 1-3 mmol: 3-5 mL.

[0015] Furthermore, in step (2), the molar volume ratio of cuprous iodide, zinc acetate, indium acetate, dodecanethiol and oleylamine is 0.2-0.3 mmol: 0.4-0.6 mmol: 0.8-1.2 mmol: 3-6 mL: 3-6 mL.

[0016] Furthermore, in step (2), the molar volume ratio of cuprous iodide, zinc acetate, indium acetate, dodecanethiol and oleylamine is 0.25 mmol:0.5 mmol:1 mmol:5 mL:5 mL.

[0017] Furthermore, in step (2), degassing is performed under vacuum at 80-100° C. for 25-35 minutes.

[0018] Furthermore, in step (2), heating is performed under nitrogen atmosphere at 130-150° C. for 10-20 min.

[0019] Furthermore, in step (3), the volume ratio of the copper indium zinc solution to the sulfur solution is 8-12:4.

[0020] Furthermore, in step (4), the volume ratio of the mixture of mercaptopropionic acid, dimethylformamide, the reaction mother liquor obtained in step (3) and n-propanol is 3-5:20-26:2:25-35.

[0021] Furthermore, in step (4), the volume ratio of the mixture of mercaptopropionic acid, dimethylformamide, the reaction mother liquor obtained in step (3) and n-propanol is 4:24:2:30.

[0022] Furthermore, in step (4), degassing is performed under vacuum at 45-55° C. for 25-35 min.

[0023] Furthermore, in step (4), heating is performed under nitrogen atmosphere at 100-130° C. for 10-20 min.

[0024] Furthermore, in step (4), the concentration of the water-soluble copper-defect-rich quantum dot solution is 0.06-0.07 g / L.

[0025] Furthermore, in step (4), the concentration of the water-soluble copper-defect-rich quantum dot solution is 0.067 g / L.

[0026] The present invention also provides a method for constructing the above-mentioned water-soluble copper-defect-rich quantum dot light-driven carbon dioxide reduction system, comprising the following steps: adding a water-soluble copper-defect-rich quantum dot solution, deionized water and ascorbic acid into a stoppered quartz bottle, degassing for 2-4 minutes under a vacuum state, and then filling with gas under a carbon dioxide atmosphere for 2-4 minutes, and cyclically degassing and filling 2-3 times to obtain a water-soluble copper-defect-rich quantum dot light-driven carbon dioxide reduction system.

[0027] The present invention also provides an application of the above-mentioned light-driven reduction of carbon dioxide system based on water-soluble copper-rich defect quantum dots in light-driven reduction of carbon dioxide to produce fuel.

[0028] The present invention has the following beneficial effects:

[0029] 1. In terms of system materials, the present invention introduces copper defect sites into quantum dots, thereby improving the intrinsic conductivity of the catalyst and the activity of the reaction sites. At the same time, it generates intermediate states in the energy band of the catalyst that are conducive to the separation and transfer of photogenerated electron-hole pairs, reducing the photocorrosion of the catalyst and systematically solving the key problem of low activity and low stability of existing photocatalysts.

[0030] 2. In terms of system technology, this invention has developed a technology for converting water-insoluble quantum dots into water-soluble quantum dots. Through a dual-solvent method using two solvents of different polarities, the non-polar ligands on the quantum dot surface are fully exchanged and converted into polar ligands, which optimizes the quantum dot preparation process. This allows the final catalyst to form a stable dispersed phase with the reaction medium, eliminating the need for stirring during operation and reducing catalyst sedimentation.

[0031] 3. The present invention precisely controls the concentration of the copper source when preparing quantum dots, thereby preparing quantum dots rich in copper defects with high activity and high stability.

[0032] 4. When the system of the present invention is working, stirring is not required. The quantum dots are in the form of a colloidal aqueous solution. Under outdoor sunlight, bubbles can be observed in the solution, which is the photoreduction of carbon dioxide to produce carbon monoxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a picture of the light-driven carbon dioxide reduction system of the present invention. DETAILED DESCRIPTION

[0034] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples are only used to explain the present invention and are not intended to limit the scope of the invention. In the embodiments, if specific conditions are not specified, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0035] Example 1:

[0036] A light-driven carbon dioxide reduction system based on water-soluble copper-rich defect quantum dots (see Figure 1 ), the construction method includes the following steps:

[0037] (1) Dissolve 2 mmol of sulfur powder in 4 mL of oleylamine to prepare a sulfur solution;

[0038] (2) 0.25 mmol of cuprous iodide, 0.5 mmol of zinc acetate, 1 mmol of indium acetate, 5 mL of dodecanethiol, and 5 mL of oleylamine were mixed and placed in a 50 mL three-necked flask. The mixture was degassed at 90°C for 30 min under vacuum and heated at 140°C for 15 min under nitrogen atmosphere to prepare a copper indium zinc solution.

[0039] (3) The copper indium zinc solution prepared in step (2) was heated at 230°C for 10 minutes to form quantum dots, and the sulfur solution prepared in step (1) was added dropwise with a syringe and heated at 200°C for 20 minutes to grow quantum dots. The three-necked flask of the reaction device was then placed in cold water to quench the reaction, thereby obtaining a WU-V Cu -CuInS2 reaction mother liquor, i.e., reaction mother liquor containing water-insoluble copper-defect-rich quantum dots (transferred to a centrifuge tube for collection and stored in a refrigerator at 4°C);

[0040] (4) 4 mL of mercaptopropionic acid and 24 mL of dimethylformamide were mixed and placed in a 50 mL three-necked flask. 2 mL of the reaction mother solution obtained in step (3) was added. The mixture was degassed at 50 ° C for 30 min under vacuum and heated at 120 ° C for 15 min under nitrogen atmosphere to fully exchange the ligands on the surface of the quantum dots. The three-necked flask of the reaction device was then placed in cold water for quenching. 30 mL of n-propanol was used for precipitation. The resulting precipitate was dissolved in 30 mL of deionized water to obtain WS-V. Cu -CuInS2 solution, i.e., a water-soluble copper-defect-rich quantum dot solution (concentration of 0.067 g / L, transferred to a centrifuge tube for collection and stored in a refrigerator at 4°C);

[0041] (5) 3 mL of the water-soluble copper-defect-rich quantum dot solution prepared in step (4), 2 mL of deionized water, and 88 mg of ascorbic acid were added to a 50 mL stoppered quartz bottle, shaken thoroughly, degassed for 3 min under vacuum, and then aerated for 3 min under a carbon dioxide atmosphere. The degassing and aeration cycle was repeated 3 times to obtain a light-driven carbon dioxide reduction system based on water-soluble copper-defect-rich quantum dots.

[0042] Example 2:

[0043] A light-driven carbon dioxide reduction system based on water-soluble copper-rich defect quantum dots is constructed, and the construction method includes the following steps:

[0044] (1) Dissolve 1 mmol of sulfur powder in 3 mL of oleylamine to prepare a sulfur solution;

[0045] (2) 0.2 mmol of cuprous iodide, 0.4 mmol of zinc acetate, 0.8 mmol of indium acetate, 3 mL of dodecanethiol, and 3 mL of oleylamine were mixed and placed in a 50 mL three-necked flask. The mixture was degassed at 80°C for 25 min under vacuum and heated at 130°C for 10 min under nitrogen atmosphere to prepare a copper indium zinc solution.

[0046] (3) The copper indium zinc solution prepared in step (2) was heated at 200°C for 8 minutes to form quantum dots, and the sulfur solution prepared in step (1) was added dropwise with a syringe and heated at 180°C for 18 minutes to grow quantum dots. The three-necked flask of the reaction device was then placed in cold water to quench the reaction, thereby obtaining a WU-V Cu -CuInS2 reaction mother liquor, i.e., reaction mother liquor containing water-insoluble copper-defect-rich quantum dots (transferred to a centrifuge tube for collection and stored in a refrigerator at 4°C);

[0047] (4) 3 mL of mercaptopropionic acid and 20 mL of dimethylformamide were mixed and placed in a 50 mL three-necked flask. 2 mL of the reaction mother solution prepared in step (3) was added. The mixture was degassed under vacuum at 45 ° C for 25 min, and heated at 100 ° C for 10 min under nitrogen atmosphere to fully exchange the ligands on the surface of the quantum dots. The three-necked flask of the reaction device was then placed in cold water for quenching, and then 25 mL of n-propanol was used for precipitation. The resulting precipitate was dissolved in deionized water to obtain WS-V. Cu -CuInS2 solution, i.e., a water-soluble copper-defect-rich quantum dot solution (concentration of 0.06 g / L, transferred to a centrifuge tube for collection and stored in a refrigerator at 4°C);

[0048] (5) 3 mL of the water-soluble copper-defect-rich quantum dot solution prepared in step (4), 1 mL of deionized water, and 80 mg of ascorbic acid were added to a 50 mL stoppered quartz bottle, shaken thoroughly, degassed for 2 min under vacuum, and then aerated for 2 min under a carbon dioxide atmosphere. The degassing and aeration cycle was repeated twice to obtain a water-soluble copper-defect-rich quantum dot light-driven carbon dioxide reduction system.

[0049] Example 3:

[0050] A light-driven carbon dioxide reduction system based on water-soluble copper-rich defect quantum dots is constructed, and the construction method includes the following steps:

[0051] (1) Dissolve 3 mmol of sulfur powder in 5 mL of oleylamine to prepare a sulfur solution;

[0052] (2) 0.3 mmol of cuprous iodide, 0.6 mmol of zinc acetate, 1.2 mmol of indium acetate, 6 mL of dodecanethiol, and 6 mL of oleylamine were mixed and placed in a 50 mL three-necked flask. The mixture was degassed at 100°C for 35 min under vacuum and heated at 150°C for 20 min under nitrogen atmosphere to prepare a copper indium zinc solution.

[0053] (3) The copper indium zinc solution prepared in step (2) was heated at 250°C for 12 minutes to form quantum dots, and the sulfur solution prepared in step (1) was added dropwise with a syringe and heated at 220°C for 22 minutes to grow quantum dots. The three-necked flask of the reaction device was then placed in cold water to quench the reaction, thereby obtaining a WU-V Cu -CuInS2 reaction mother liquor, i.e., reaction mother liquor containing water-insoluble copper-defect-rich quantum dots (transferred to a centrifuge tube for collection and stored in a refrigerator at 4°C);

[0054] (4) 5 mL of mercaptopropionic acid and 26 mL of dimethylformamide were mixed and placed in a 50 mL three-necked flask. 2 mL of the reaction mother solution prepared in step (3) was added. The mixture was degassed at 55 ° C for 35 min in a vacuum state and heated at 130 ° C for 20 min in a nitrogen atmosphere to fully exchange the ligands on the surface of the quantum dots. The three-necked flask of the reaction device was then placed in cold water for quenching. 35 mL of n-propanol was then used for precipitation. The resulting precipitate was dissolved in deionized water to obtain WS-V. Cu -CuInS2 solution, i.e., a water-soluble copper-defect-rich quantum dot solution (concentration of 0.07 g / L, transferred to a centrifuge tube for collection and stored in a refrigerator at 4°C);

[0055] (5) 3 mL of the water-soluble copper-defect-rich quantum dot solution prepared in step (4), 3 mL of deionized water, and 90 mg of ascorbic acid were added to a 50 mL stoppered quartz bottle, shaken thoroughly, degassed under vacuum for 4 min, and then aerated under a carbon dioxide atmosphere for 4 min. The degassing and aeration cycle was repeated 3 times to obtain a light-driven carbon dioxide reduction system based on water-soluble copper-defect-rich quantum dots.

[0056] Comparative Example 1:

[0057] A light-driven carbon dioxide reduction system based on water-insoluble copper-rich defect quantum dots is constructed, the construction method comprising the following steps:

[0058] The ligands on the surface of the quantum dots in step (4) are not fully exchanged, and the rest are the same as in Example 1. Comparative Example 2:

[0059] A system for light-driven carbon dioxide reduction based on water-soluble quantum dots is constructed, the method comprising the following steps:

[0060] In step (2), 1 mmol of cuprous iodide,

[0061] In step (3), a reaction mother solution containing WU-CuInS2, i.e., a reaction mother solution containing water-insoluble quantum dots, is prepared;

[0062] In step (4), a WS-CuInS2 solution, i.e., a water-soluble quantum dot solution, is prepared;

[0063] The rest is the same as Example 1.

[0064] Comparative Example 3:

[0065] A light-driven carbon dioxide reduction system based on water-insoluble quantum dots is constructed by the following steps:

[0066] The ligand full exchange process on the surface of the quantum dots in step (4) is not included, and the rest is the same as that in Comparative Example 2.

[0067] Test example

[0068] The carbon monoxide generation rate (mmol / h / g) below refers to the number of millimoles generated per gram of quantum dots per hour.

[0069] 1. The performance of the light-driven carbon dioxide reduction systems prepared in Example 1 and Comparative Examples 1-3 was tested. The light source used was indoor simulated sunlight. The results are shown in Table 1.

[0070] Table 1 Performance of light-driven carbon dioxide reduction system under indoor simulated sunlight

[0071]

[0072] As shown in Table 1, only the water-soluble copper-rich quantum dots WS-V Cu -CuInS2 has the best light-driven carbon monoxide generation rate; and compared with water-insoluble quantum dots, the performance of water-soluble quantum dots can be improved by 20-100 times.

[0073] 2. The light-driven carbon dioxide reduction system prepared in Example 1 was subjected to performance tests under indoor simulated sunlight and outdoor natural sunlight conditions. The results are shown in Table 2.

[0074] Table 2 Performance of light-driven carbon dioxide reduction system under different light conditions

[0075]

[0076] As shown in Table 2, the performance of outdoor natural sunlight in driving the reduction of carbon dioxide to fuel is far inferior to that of indoor simulated sunlight due to cloud cover and changes in the actual angle of sunlight incidence. Its performance is roughly only 1 / 5-1 / 4 of the latter. However, the product selectivity is almost the same, indicating that the main driving force of the two is the light intensity.

[0077] 3. The light-driven carbon dioxide reduction system prepared in Example 1 and Examples 1-3 (Example 1: J.Am.Chem.Soc.10.1021 / jacs.2c08639; Example 2: Angew.Chem.,In.Ed.10.1002 / anie.202207600; Example 3: Adv.Mater.10.1002 / adma.202106662) were performance tested, and the results are shown in Table 3.

[0078] Table 3 Performance comparison of light-driven carbon dioxide reduction system and other products

[0079]

[0080] As shown in Table 3, the water-soluble copper-rich quantum dots WS-V Cu -The light-driven reduction of carbon dioxide to fuel system constructed with CuInS2 has an excellent sunlight-driven conversion rate of carbon monoxide and excellent stability, and has achieved the best performance record of the light-driven reduction of carbon dioxide to carbon monoxide system in the world.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A light-driven carbon dioxide reduction system based on water-soluble copper-rich defect quantum dots, characterized in that: The system includes a stoppered quartz bottle containing water-soluble copper-rich defect quantum dots, deionized water and ascorbic acid; The water-soluble copper-defect-rich quantum dots are prepared by the following method: (1) Dissolve sulfur powder in oleylamine to prepare a sulfur solution; (2) Mixing cuprous iodide, zinc acetate, indium acetate, dodecanethiol, and oleylamine, degassing, and heating to prepare a copper indium zinc solution; (3) heating the copper indium zinc solution obtained in step (2) at 200-250° C. for 8-12 min, adding dropwise the sulfur solution obtained in step (1), heating at 180-220° C. for 18-22 min, and quenching in cold water to obtain a reaction mother liquor containing WU-VCu-CuInS2, i.e., a reaction mother liquor containing water-insoluble copper-defect quantum dots; (4) Mercaptopropionic acid and dimethylformamide are mixed, and the reaction mother liquor prepared in step (3) is added, degassed, heated, and quenched in cold water. Then, n-propanol is used for precipitation, and the resulting precipitate is dissolved in deionized water to prepare a WS-VCu-CuInS2 solution, i.e., a water-soluble copper-defect-rich quantum dot solution.

2. The light-driven carbon dioxide reduction system based on water-soluble copper-rich defect quantum dots according to claim 1 is characterized in that: The volume-to-mass ratio of the stoppered quartz bottle, the water-soluble copper-defect-rich quantum dots, deionized water, and ascorbic acid is 45-55 mL: 0.18-0.21 mg: 4-6 mL: 80-90 mg.

3. The light-driven carbon dioxide reduction system based on water-soluble copper-rich defect quantum dots according to claim 1 is characterized in that: In step (1), the molar volume ratio of sulfur powder to oleylamine is 1-3 mmol:3-5 mL.

4. The light-driven carbon dioxide reduction system based on water-soluble copper-rich defect quantum dots according to claim 1 is characterized in that: In step (2), the molar volume ratio of cuprous iodide, zinc acetate, indium acetate, dodecanethiol and oleylamine is 0.2-0.3 mmol: 0.4-0.6 mmol: 0.8-1.2 mmol: 3-6 mL: 3-6 mL.

5. The light-driven carbon dioxide reduction system based on water-soluble copper-rich defect quantum dots according to claim 1 is characterized in that: In step (3), the volume ratio of the copper indium zinc solution to the sulfur solution is 8-12:

4.

6. The light-driven carbon dioxide reduction system based on water-soluble copper-rich defect quantum dots according to claim 1, characterized in that: In step (4), the volume ratio of mercaptopropionic acid, dimethylformamide, the reaction mother liquor obtained in step (3) and n-propanol is 3-5:20-26:2:25-35.

7. The light-driven carbon dioxide reduction system based on water-soluble copper-rich defect quantum dots according to claim 1, characterized in that: In step (4), the concentration of the water-soluble copper-defect-rich quantum dot solution is 0.06-0.07 g / L.

8. The method for constructing a light-driven carbon dioxide reduction system based on water-soluble copper-rich defect quantum dots according to any one of claims 1 to 7, characterized in that: The following steps are involved: A water-soluble copper-defect-rich quantum dot solution, deionized water and ascorbic acid are added to a stoppered quartz bottle, degassed under vacuum for 2-4 minutes, then inflated under a carbon dioxide atmosphere for 2-4 minutes, and the degassing and inflating cycle is repeated 2-3 times to obtain a light-driven carbon dioxide reduction system based on water-soluble copper-defect-rich quantum dots.

9. Use of the light-driven reduction of carbon dioxide system based on water-soluble copper-rich defect quantum dots according to any one of claims 1 to 7 in light-driven reduction of carbon dioxide to produce fuel.

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