An interfacial integrated system for coupled photo-driven CO2 reduction and seawater desalination and its preparation method

Abstract

This invention discloses an interface-integrated system for the coupled reaction of light-driven CO2 reduction and seawater desalination, and its preparation method. The interface-integrated system is constructed using a PVDF membrane as the interface carrier material and a 3DOM-TiO2 / Cu2SnS3 heterojunction as the photocatalyst and photothermal material. The system is prepared by using styrene (St), polyvinylpyrrolidone (PVP), K2S2O8, tetrabutyl titanate (TBOT), anhydrous ethanol (C2H6O), nitric acid (HNO3), copper chloride (CuCl2), stannous chloride (SnCl2), thiourea (CH4N2S), ethylene glycol (CH2OH)2, N-methylpyrrolidone (NMP), and ammonia (NH3·H2O). This integrated system breaks through the limitations of traditional single-function systems and demonstrates important application value in the field of CO2 resource utilization and seawater desalination co-production.

Description

Technical Field

[0001] This invention belongs to the field of photothermal / photocatalytic materials, specifically relating to an interface integrated system for the coupled reaction of photo-driven CO2 reduction and seawater desalination and its preparation method. Background Technology

[0002] The utilization of solar energy mainly involves three categories: photothermal conversion, photoelectric conversion, and photochemical conversion. Among these, photocatalytic CO2 reduction and photothermal seawater desalination, achieved through photochemical and photothermal conversion respectively, are considered important strategies for alleviating global warming, freshwater shortages, and fossil fuel scarcity. However, these two technologies are currently mostly studied independently. Constructing an interface-integrated system can achieve the coupled reaction of gas-solid phase CO2 reduction and liquid-solid phase seawater desalination. That is, the photothermal material in the interface-integrated system can accelerate seawater evaporation, while the catalytic material in the interface-integrated system can convert CO2 gas and H2O vapor into high-value hydrocarbons, thereby improving reaction efficiency and reducing reaction costs.

[0003] Developing high-performance catalytic materials is crucial for achieving efficient photocatalytic CO2 reduction. Titanium dioxide (TiO2), due to its high activity, strong stability, low cost, and environmental friendliness, is hailed as one of the most promising catalysts of the 21st century and has been widely used in wastewater treatment, hydrogen production, and CO2 reduction. However, TiO2's low specific surface area and wide bandgap result in few active sites and weak photoresponse, leading to unsatisfactory CO2 conversion efficiency. Constructing a three-dimensional ordered macroporous (3DOM) structure can effectively increase the exposure of active sites and enhance light absorption: on the one hand, traditional catalysts can only utilize their surface active sites, making it difficult to effectively expose internal active sites, while the 3DOM structure can significantly increase the material's specific surface area and release internal active sites; on the other hand, the interconnected porous structure of the 3DOM catalyst can periodically regulate the light transmission path through the slow photon effect, thereby enhancing sunlight absorption performance. Although the 3DOM structure can enhance the light absorption performance of the catalyst to some extent, the inherent wide bandgap of TiO2 still limits its photoresponse range to the ultraviolet region.

[0004] Constructing heterojunctions with narrow-bandgap semiconductors is an effective strategy to broaden the photoresponse range of TiO2 to the visible and even near-infrared regions. Bimetallic chalcogenides Cu2SnS3, with its narrow direct bandgap (approximately 1.5 eV), can achieve full-spectrum absorption across the ultraviolet-visible-near-infrared spectrum, making it an ideal candidate material for TiO2 co-catalysts. Simultaneously, introducing sulfur vacancies into Cu2SnS3 can further enhance light absorption, accelerate charge transport, and improve the catalyst's redox capacity. Furthermore, the broad-spectrum light absorption characteristics of Cu2SnS3 endow it with excellent photothermal conversion performance, making it a potential candidate for seawater desalination. Due to the powder characteristics of TiO2 and Cu2SnS3, developing suitable interfacial supports is crucial for constructing integrated CO2 reduction and seawater desalination systems. Polyvinylidene fluoride (PVDF) membranes, with their high strength, lightweight, and good flexibility, are considered ideal "breathing materials" because they effectively block liquid water penetration while allowing water vapor to pass freely, exhibiting both excellent breathability and waterproofing properties. Therefore, this patent designs and constructs a novel PVDF / 3DOM-TiO2 / Cu2SnS3 integrated system. This system uses PVDF membrane as the interface carrier material and 3DOM-TiO2 / Cu2SnS3 heterojunction as the photocatalyst and photothermal material, which can realize the coupled reaction of photocatalytic CO2 reduction and photothermal seawater desalination. Summary of the Invention

[0005] The purpose of this invention is to design an interface integrated system and its preparation method for a photo-driven CO2 reduction and seawater desalination coupling reaction, thereby realizing the photocatalytic CO2 reduction and photothermal seawater desalination coupling reaction.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first objective of this invention is to propose an interface-integrated system for the coupled reaction of light-driven CO2 reduction and seawater desalination. The interface-integrated system is constructed using polyvinylidene fluoride (PVDF) membrane as the interface carrier material and 3DOM-TiO2 / Cu2SnS3 heterojunction as the photocatalyst and photothermal material. The system is characterized by being prepared using styrene (St), polyvinylpyrrolidone (PVP), potassium persulfate (K2S2O8), tetrabutyl titanate (TBOT), anhydrous ethanol (C2H6O), nitric acid (HNO3), copper chloride (CuCl2), stannous chloride (SnCl2), thiourea (CH4N2S), ethylene glycol (CH2OH)2, N-methylpyrrolidone (NMP), and ammonia (NH3·H2O).

[0007] The second objective of this invention is to provide a method for preparing an interface-integrated system for the coupled reaction of light-driven CO2 reduction and seawater desalination. The preparation method of the interface-integrated system is as follows: Step 1: Preparation of a three-dimensionally ordered polystyrene nanosphere template. Polystyrene nanospheres with a diameter of 200 nm were prepared by emulsion polymerization. St, PVP, and deionized water were added to a three-necked flask and stirred at room temperature for 10-200 min. K₂S₂O₈ was then added as an initiator while stirring, and nitrogen gas was bubbled into the reaction system to purge air from the three-necked flask. Finally, the mixture was heated at 50-200 °C for 12-24 h to obtain a polystyrene nanosphere latex solution. The obtained latex solution was centrifuged multiple times to obtain a precipitate, which was then dried to prepare the three-dimensionally ordered polystyrene template.

[0008] Step 2: Preparation of 3DOM-TiO2 catalyst. TBOT, C2H6O, and HNO3 were mixed uniformly in a glass beaker using magnetic stirring. The prepared polystyrene nanosphere template was immersed in the above mixed solution and allowed to stand for 1-12 h. The template was then removed and dried overnight at room temperature. The dried template was placed in a crucible and calcined at 400-800 ℃ for 1-8 h with a programmed heating rate of 1-10 ℃ / min to obtain three-dimensional ordered macroporous TiO2 (3DOM-TiO2).

[0009] Step 3: Construction of the 3DOM-TiO2 / Cu2SnS3 heterojunction catalyst. The 3DOM-TiO2 / Cu2SnS3 heterojunction was prepared using a solvothermal method. CuCl2, SnCl2, and CH4N2S were added to (CH2OH)2 and stirred until completely dissolved. Then, a certain amount of 3DOM-TiO2 was added and stirring continued for 10-60 min. The mixed solution was transferred to a stainless steel reactor and reacted at 100-300 ℃ for 6-24 h. After centrifugation, the product was washed 1-5 times with deionized water and ethanol, respectively. Finally, it was dried in a vacuum oven for 6-12 h to prepare the 3DOM-TiO2 / Cu2SnS3 heterojunction catalyst.

[0010] Step 4: Constructing the PVDF / 3DOM-TiO2 / Cu2SnS3 integrated system. Dissolve PVDF in NMP and stir for 30 min until completely dissolved. Add a certain amount of NH3·H2O and continue stirring for 1-8 h. Add a certain amount of PVDF solution and 3DOM-TiO2 / Cu2SnS3 heterojunction catalyst to a centrifuge tube, sonicate for 10-60 min, pour the mixture into a petri dish, and dry at room temperature to form a film. Finally, immerse the petri dish in deionized water to peel off the film, thus obtaining the PVDF / 3DOM-TiO2 / Cu2SnS3 integrated system (PVDF / 3DOM-TiO / CSS).

[0011] Furthermore, in step 1, the amount of St is 5-50 g, the amount of PVP is 1-10 g, and the mass of K2S2O8 is 0.1-3 g.

[0012] Furthermore, in step 2, the volume of TBOT is 5-50 mL, the volume of C2H6O is 5-30 mL, and the amount of HNO3 is 0.5-5 mL.

[0013] Furthermore, in step 3, the mass of CuCl2 is 0.1-1.0 g, the mass of SnCl2 is 0.1-2.0 g, the mass of CH4N2S is 0.1-0.5 g, the volume of (CH2OH)2 is 30-100 mL, and the amount of 3DOM-TiO2 is 0.1-10 g.

[0014] Furthermore, in step 4, the amount of PVDF used is 1-20 g, the volume of NMP is 30-200 mL, and the amount of NH3·H2O used is 1-5 mL. The amounts of PVDF solution and 3DOM-TiO2 / Cu2SnS3 heterojunction are 1-10 mL and 10-200 mg, respectively.

[0015] Compared with the prior art, the present invention has the following beneficial effects: While traditional photocatalytic CO2 reduction and solar-powered seawater desalination are both light-driven reactions, their energy efficiency is limited by their independent operation modes. This patent proposes a bifunctional interface coupling system based on a PVDF membrane carrier, achieving synergistic conversion of light, heat, and chemical energy through in-situ integration of a 3DOM-TiO2 / Cu2SnS3 heterojunction. The innovation of this system lies in: (1) Synergistic energy conversion mechanism: The heterojunction catalyst encapsulated in the PVDF matrix generates spatially separated electron-hole pairs under photoexcitation. Among them, the highly active holes release protons through interfacial water vapor oxidation, while the photogenerated electrons drive the reduction reaction of CO2 with protons to generate CO, realizing the gas-solid phase photocatalytic CO2 reduction reaction; 2) Broadband photothermal enhancement effect: Based on the narrow bandgap characteristics of Cu2SnS3, the system has good light-harvesting ability in the ultraviolet-visible-near infrared band, exhibiting excellent photothermal conversion performance, accelerating the water evaporation rate, and realizing liquid-solid phase seawater desalination reaction. 3) Sustainable operation advantages: After the reaction, the catalyst can be recovered through simple physical separation, which will not cause secondary pollution, and the carrier material can be reused, saving reaction costs.

[0016] This integrated system breaks through the limitations of traditional single functions and demonstrates significant application value in the fields of CO2 resource utilization and seawater desalination co-production. Attached Figure Description

[0017] Figure 1 This is a comparison chart of the coupling reaction performance of CO2 reduction and seawater desalination using PVDF / 3DOM-TiO / CSS with different ratios of 3DOM-TiO2 and Cu2SnS3.

[0018] Figure 2 This is a comparison chart of the coupling reaction performance of CO2 reduction and seawater desalination with and without PVDF membrane encapsulation in 3DOM-TiO / CSS heterojunction.

[0019] Figure 3 This is a comparison chart of the CO2 reduction and seawater desalination coupling reaction performance of PVDF / 3DOM-TiO and PVDF / 3DOM-TiO / CSS integrated systems.

[0020] Figure 4 This is a comparison chart of the CO2 reduction and seawater desalination coupling reaction performance of PVDF / CSS and PVDF / 3DOM-TiO / CSS integrated systems. Detailed Implementation

[0021] The following is in conjunction with the appendix Figure 1-4 Further explanation of the present invention: This invention discloses an interface-integrated system for a photo-driven CO2 reduction and seawater desalination coupling reaction. The interface-integrated system materials include styrene (St), polyvinylpyrrolidone (PVP), K2S2O8, tetrabutyl titanate (TBOT), anhydrous ethanol (C2H6O), nitric acid (HNO3), copper chloride (CuCl2), stannous chloride (SnCl2), thiourea (CH4N2S), ethylene glycol (CH2OH)2, N-methylpyrrolidone (NMP), and ammonia (NH3·H2O).

[0022] The method for preparing the interfacial integrated material for the coupled reaction of light-driven CO2 reduction and seawater desalination involved in this invention is as follows: Add 5-50 g of St, 1-10 g of PVP, and 30-500 mL of deionized water to a three-necked flask and stir at room temperature for 10-200 min. Then, while stirring, add 0.1-3 g of K₂S₂O₈ as an initiator, and purge the air from the three-necked flask with nitrogen gas. Finally, heat the mixture at 50-200 °C for 12-24 h to obtain a polystyrene nanosphere latex solution. Centrifuge the obtained latex solution multiple times to obtain a precipitate, which, after drying, can be used to prepare a three-dimensionally ordered polystyrene template. Mix 5-50 mL of TBOT, 5-30 mL of C₂H₆O, and 0.5-5 mL of HNO₃ in a glass beaker using magnetic stirring until homogeneous. Immerse the prepared polystyrene nanosphere template in the above mixed solution and let it stand for 1-12 h. Then remove the template and dry it overnight at room temperature. The dried template is placed in a crucible and calcined at 400-800 °C for 1-8 h with a heating rate of 1-10 °C / min to obtain 3DOM-TiO2. A solvothermal method is used to prepare 3DOM-TiO2 / Cu2SnS3 heterojunctions. 0.1-1.0 g of CuCl2, 0.1-2.0 g of SnCl2, and 0.1-0.5 g of CH4N2S are added to 30-100 mL of (CH2OH)2 and stirred until completely dissolved. Then, 0.1-10 g of 3DOM-TiO2 is added and stirring continues for 10-60 min. The mixed solution is transferred to a stainless steel reactor and reacted at 100-300 °C for 6-24 h. After centrifugation, the product is washed 1-5 times with deionized water and ethanol, respectively. Finally, it is dried in a vacuum oven for 6-12 h to prepare the 3DOM-TiO2 / Cu2SnS3 heterojunction. Dissolve 1-20 g of PVDF in 30-200 mL of NMP and stir for 30 min until completely dissolved. Add 1-5 mL of NH3·H2O and continue stirring for 1-8 h. Add 1-10 mL of the PVDF solution and 10-200 mg of 3DOM-TiO2 / Cu2SnS3 to a centrifuge tube, sonicate for 10-60 min, pour the mixture into a culture dish, and dry at room temperature to form a film. Finally, immerse the culture dish in deionized water to peel off the film, thus obtaining the PVDF / 3DOM-TiO2 / CSS integrated system. Example 1

[0023] 30 g of St, 5 g of PVP, and 200 mL of deionized water were added to a three-necked flask and stirred at room temperature for 60 min. Then, 2 g of K₂S₂O₈ was added as an initiator while stirring, and nitrogen gas was bubbled into the reaction system to purge air from the three-necked flask. Finally, the mixture was heated at 150 °C for 18 h to obtain a polystyrene nanosphere latex solution. The obtained latex solution was centrifuged multiple times to obtain a precipitate, which was then dried to prepare a three-dimensionally ordered polystyrene template. 20 mL of TBOT, 10 mL of C₂H₆O, and 3 mL of HNO₃ were mixed uniformly in a glass beaker using magnetic stirring. The prepared polystyrene nanosphere template was immersed in the above mixed solution and allowed to stand for 6 h. The template was then removed and dried overnight at room temperature. The dried template was placed in a crucible and calcined at 600 °C for 6 h at a programmed heating rate of 5 °C / min to obtain 3DOM-TiO₂. 3DOM-TiO2 / Cu2SnS3 heterojunctions were prepared using a solvothermal method. 0.5 g of CuCl2, 0.3 g of SnCl2, and 0.2 g of CH4N2S were added to 60 mL of (CH2OH)2 and stirred until completely dissolved. Then, 3 g of 3DOM-TiO2 was added and stirring continued for 30 min. The mixture was transferred to a stainless steel reactor and reacted at 200 °C for 12 h. The product was centrifuged and washed three times each with deionized water and ethanol. Finally, it was dried in a vacuum oven for 10 h to obtain the 3DOM-TiO2 / Cu2SnS3 heterojunction. Alternatively, 10 g of PVDF was dissolved in 100 mL of NMP and stirred for 30 min until completely dissolved. 3 mL of NH3·H2O was added and stirring continued for 6 h. Add 3 mL of PVDF solution and 50 mg of 3DOM-TiO2 / Cu2SnS3 to a centrifuge tube, sonicate for 30 min, pour the mixture into a culture dish, dry it to form a film, and then immerse the culture dish in deionized water to peel it off, thus obtaining the PVDF / 3DOM-TiO2 / CSS integrated system. Example 2

[0024] 10 g of St, 5 g of PVP, and 100 mL of deionized water were added to a three-necked flask and stirred at room temperature for 60 min. Then, 2 g of K₂S₂O₈ was added as an initiator while stirring, and nitrogen gas was bubbled into the reaction system to purge air from the three-necked flask. Finally, the mixture was heated at 150 °C for 12 h to obtain a polystyrene nanosphere latex solution. The obtained latex solution was centrifuged multiple times to obtain a precipitate, which was then dried to prepare a three-dimensionally ordered polystyrene template. 5 mL of TBOT, 20 mL of C₂H₆O, and 2 mL of HNO₃ were mixed uniformly in a glass beaker using magnetic stirring. The prepared polystyrene nanosphere template was immersed in the above mixed solution and allowed to stand for 12 h. The template was then removed and dried overnight at room temperature. The dried template was placed in a crucible and calcined at 500 °C for 4 h at a programmed heating rate of 2 °C / min to obtain 3DOM-TiO₂. 3DOM-TiO2 / Cu2SnS3 heterojunctions were prepared using a solvothermal method. 0.3 g of CuCl2, 0.2 g of SnCl2, and 0.5 g of CH4N2S were added to 80 mL of (CH2OH)2 and stirred until completely dissolved. Then, 5 g of 3DOM-TiO2 was added, and stirring continued for 10–60 min. The mixture was transferred to a stainless steel reactor and reacted at 200 °C for 18 h. The product was centrifuged and washed three times each with deionized water and ethanol. Finally, it was dried in a vacuum oven for 12 h to obtain the 3DOM-TiO2 / Cu2SnS3 heterojunction. Alternatively, 10 g of PVDF was dissolved in 50 mL of NMP and stirred for 30 min until completely dissolved. 2 mL of NH3·H2O was added, and stirring continued for 6 h. Add 5 mL of PVDF solution and 50 mg of 3DOM-TiO2 / Cu2SnS3 to a centrifuge tube, sonicate for 30 min, pour the mixture into a culture dish, and dry at room temperature to form a film. Finally, immerse the culture dish in deionized water to peel off the film, thus obtaining the PVDF / 3DOM-TiO2 / CSS integrated system. Example 3

[0025] 15 g of St, 3 g of PVP, and 200 mL of deionized water were added to a three-necked flask and stirred at room temperature for 50 min. Then, 2 g of K₂S₂O₈ was added as an initiator while stirring, and nitrogen gas was bubbled into the reaction system to purge air from the three-necked flask. Finally, the mixture was heated at 180 °C for 12 h to obtain a polystyrene nanosphere latex solution. The obtained latex solution was centrifuged multiple times to obtain a precipitate, which was then dried to prepare a three-dimensionally ordered polystyrene template. 5 mL of TBOT, 10 mL of C₂H₆O, and 2 mL of HNO₃ were mixed uniformly in a glass beaker using magnetic stirring. The prepared polystyrene nanosphere template was immersed in the above mixed solution and allowed to stand for 8 h. The template was then removed and dried overnight at room temperature. The dried template was placed in a crucible and calcined at 500 °C for 6 h at a programmed heating rate of 2 °C / min to obtain 3DOM-TiO₂. 3DOM-TiO2 / Cu2SnS3 heterojunctions were prepared using a solvothermal method. 0.5 g of CuCl2, 1 g of SnCl2, and 0.3 g of CH4N2S were added to 60 mL of (CH2OH)2 and stirred until completely dissolved. Then, 5 g of 3DOM-TiO2 was added, and stirring continued for 30 min. The mixture was transferred to a stainless steel reactor and reacted at 200 °C for 24 h. The product was centrifuged and washed three times each with deionized water and ethanol. Finally, it was dried in a vacuum oven for 6 h to obtain the 3DOM-TiO2 / Cu2SnS3 heterojunction. Alternatively, 5 g of PVDF was dissolved in 80 mL of NMP and stirred for 30 min until completely dissolved. Then, 3 mL of NH3·H2O was added, and stirring continued for 4 h. Add 10 mL of PVDF solution and 150 mg of 3DOM-TiO2 / Cu2SnS3 to a centrifuge tube, sonicate for 30 min, pour the mixture into a culture dish, and dry at room temperature to form a film. Finally, immerse the culture dish in deionized water to peel off the film, thus obtaining the PVDF / 3DOM-TiO2 / CSS integrated system.

[0026] Comparative Example 1

[0027] 10 g of St, 5 g of PVP, and 100 mL of deionized water were added to a three-necked flask and stirred at room temperature for 60 min. Then, 2 g of K₂S₂O₈ was added as an initiator while stirring, and nitrogen gas was bubbled into the reaction system to purge air from the three-necked flask. Finally, the mixture was heated at 150 °C for 12 h to obtain a polystyrene nanosphere latex solution. The obtained latex solution was centrifuged multiple times to obtain a precipitate, which was then dried to prepare a three-dimensionally ordered polystyrene template. 5 mL of TBOT, 20 mL of C₂H₆O, and 2 mL of HNO₃ were mixed uniformly in a glass beaker using magnetic stirring. The prepared polystyrene nanosphere template was immersed in the above mixed solution and allowed to stand for 12 h. The template was then removed and dried overnight at room temperature. The dried template was placed in a crucible and calcined at 500 °C for 4 h at a programmed heating rate of 2 °C / min to obtain 3DOM-TiO₂. 3DOM-TiO2 / Cu2SnS3 heterojunctions were prepared using a solvothermal method. 0.3 g of CuCl2, 0.2 g of SnCl2, and 0.5 g of CH4N2S were added to 80 mL of (CH2OH)2 and stirred until completely dissolved. Then, 5 g of 3DOM-TiO2 was added, and stirring continued for 10–60 min. The mixture was transferred to a stainless steel reactor and reacted at 200 °C for 18 h. The product was centrifuged and washed three times each with deionized water and ethanol. Finally, it was dried in a vacuum oven for 12 h to prepare PVDF-free encapsulated 3DOM-TiO2 / Cu2SnS3 powder (3DOM-TiO / CSS). Comparative Example 2

[0028] 10 g of St, 5 g of PVP, and 100 mL of deionized water were added to a three-necked flask and stirred at room temperature for 60 min. Then, 2 g of K₂S₂O₈ was added as an initiator while stirring, and nitrogen gas was bubbled into the reaction system to purge air from the three-necked flask. Finally, the mixture was heated at 150 °C for 12 h to obtain a polystyrene nanosphere latex solution. The obtained latex solution was centrifuged multiple times to obtain a precipitate, which was then dried to prepare a three-dimensionally ordered polystyrene template. 5 mL of TBOT, 20 mL of C₂H₆O, and 2 mL of HNO₃ were mixed uniformly in a glass beaker using magnetic stirring. The prepared polystyrene nanosphere template was immersed in the above mixed solution and allowed to stand for 12 h. The template was then removed and dried overnight at room temperature. The dried template was placed in a crucible and calcined at 500 °C for 4 h at a programmed heating rate of 2 °C / min to obtain 3DOM-TiO₂. Dissolve 10 g of PVDF in 50 mL of NMP and stir for 30 min until completely dissolved. Add 2 mL of NH3·H2O and continue stirring for 6 h. Add 5 mL of PVDF solution and 50 mg of 3DOM-TiO2 to a centrifuge tube, sonicate for 30 min, pour the mixture into a culture dish, and dry at room temperature to form a membrane. Finally, immerse the culture dish in deionized water to peel off the membrane, thus obtaining the PVDF / 3DOM-TiO2 control membrane (PVDF / 3DOM-TiO2). Comparative Example 3

[0029] Cu₂SnS₃ powder was prepared using a solvothermal method. 0.3 g of CuCl₂, 0.2 g of SnCl₂, and 0.5 g of CH₄N₂S were added to 80 mL of (CH₂OH)₂ and stirred until completely dissolved. The solution was then transferred to a stainless steel reactor and reacted at 200 °C for 18 h. The product was centrifuged and washed three times each with deionized water and ethanol. Finally, it was dried in a vacuum oven for 12 h to obtain Cu₂SnS₃. 10 g of PVDF was dissolved in 50 mL of NMP and stirred for 30 min until completely dissolved. 2 mL of NH₃·H₂O was added, and stirring continued for 6 h. 5 mL of the PVDF solution and 50 mg of Cu₂SnS₃ heterojunction catalyst were added to a centrifuge tube, sonicated for 30 min, and the mixture was poured into a petri dish and dried at room temperature to form a film. Finally, the petri dish was immersed in deionized water for peeling to obtain the PVDF / Cu₂SnS₃ control film (PVDF / CSS).

[0030] In Examples 1-3, the interface-integrated system for the photo-driven CO2 reduction and seawater desalination coupling reaction obtained by the technical solution of the present invention uses a PVDF membrane as the interface carrier material and a 3DOM-TiO2 / Cu2SnS3 heterojunction as the photocatalyst and photothermal material, which can realize the photocatalytic CO2 reduction and photothermal seawater desalination coupling reaction. Specific analysis is as follows: Figure 1 This is a comparison of the performance of the CO2 reduction and seawater desalination coupling reaction of PVDF / 3DOM-TiO / CSS with different 3DOM-TiO2 and Cu2SnS3 ratios. As can be seen from the figure, the PVDF / 3DOM-TiO / CSS integrated systems prepared in Examples 1-3 successfully achieved the photo-driven CO2 reduction and seawater desalination coupling reaction. Examples 1-3 show the coupling reaction performance as the 3DOM-TiO2 ratio increases. The CO2 reduction yield initially increases and then decreases. PVDF / 3DOM-TiO / CSS-2 has the highest product yield at 27.36 μmol / g, which is higher than PVDF / 3DOM-TiO / CSS-1 (23.38 μmol / g) and PVDF / 3DOM-TiO / CSS-3 (25.69 μmol / g). The seawater desalination efficiency gradually decreases with increasing 3DOM-TiO2 ratio. This is because the photothermal conversion performance of 3DOM-TiO2 is lower than that of Cu2SnS3. The seawater desalination efficiency of PVDF / 3DOM-TiO / CSS-2 is 3.71 kg / m³. 2 .

[0031] Figure 2 This is a comparison of the performance of the CO2 reduction and seawater desalination coupling reaction of 3DOM-TiO / CSS heterojunctions with and without PVDF membrane encapsulation. As can be seen from the figure, without a PVDF membrane as the interface carrier, the 3DOM-TiO / CSS control material synthesized in Comparative Example 1 could not achieve the CO2 photoreduction reaction. This is because the 3DOM-TiO / CSS powder is dispersed in water during the reaction, and the solubility of CO2 gas in water is very low, resulting in limited contact with the catalyst. Furthermore, the seawater evaporation efficiency of the 3DOM-TiO / CSS control material was only 0.53 μmol / g, far lower than the 3.71 μmol / g of the PVDF / 3DOM-TiO / CSS-2 synthesized in Example 2, demonstrating that the PVDF membrane plays a crucial role in achieving the efficient coupling reaction.

[0032] Figure 3This is a comparison of the performance of CO2 reduction and seawater desalination coupling reactions between PVDF / 3DOM-TiO and PVDF / 3DOM-TiO / CSS integrated systems. As can be seen from the figure, the PVDF / 3DOM-TiO synthesized in Comparative Example 2 can achieve the coupling reaction of CO2 reduction and seawater desalination, but the reduction efficiency and water evaporation efficiency are relatively low. Specifically, the CO2 reduction product yield is 20.69 μmol / g, lower than the 27.36 μmol / g of the PVDF / 3DOM-TiO / CSS-2 synthesized in Example 2. This is because the lack of Cu2SnS3 narrows the light response range of PVDF / 3DOM-TiO, increases carrier recombination efficiency, and affects CO2 conversion efficiency. Furthermore, the seawater desalination efficiency of PVDF / 3DOM-TiO was 2.34 μmol / g, which was much lower than the 3.71 μmol / g of PVDF / 3DOM-TiO / CSS-2 synthesized in Example 2. This is because the broad-spectrum light absorption characteristics of Cu2SnS3 endow it with excellent photothermal conversion performance, while PVDF / 3DOM-TiO lacks Cu2SnS3, resulting in a decrease in seawater desalination efficiency.

[0033] Figure 4 This is a comparison of the CO2 reduction and seawater desalination coupling reaction performance of the PVDF / CSS and PVDF / 3DOM-TiO / CSS integrated systems. As can be seen from the figure, the photocatalytic CO2 reduction efficiency of the PVDF / CSS synthesized in Comparative Example 3 is very low, only 5.35 μmol / g. Although CSS has good photo-effect performance, its valence band oxidation ability is weak, making it difficult to decompose water molecules to provide sufficient protons for CO2 reduction, resulting in low CO2 conversion efficiency. In contrast, the seawater evaporation efficiency of PVDF / CSS is higher than that of the PVDF / 3DOM-TiO / CSS integrated system synthesized in Example 2. This is because the photothermal conversion performance of Cu2SnS3 is superior to that of 3DOM-TiO2, and the proportion of Cu2SnS3 in PVDF / CSS is higher than that in PVDF / 3DOM-TiO / CSS, accelerating the seawater evaporation reaction.

[0034] Based on the analysis and comparison of the above embodiments and comparative examples, it can be seen that the synergistic effect of the PVDF membrane, the 3DOM-TiO2 / Cu2SnS3 photocatalyst, and the photothermal material can realize the coupled reaction of solar-driven CO2 reduction and seawater desalination. On the one hand, the heterojunction catalyst encapsulated in the PVDF matrix generates spatially separated electron-hole pairs under photoexcitation. Among them, highly active holes release protons through interfacial water vapor oxidation, while photogenerated electrons drive CO2 to undergo a reduction reaction with protons to generate CO, realizing a gas-solid phase photocatalytic CO2 reduction reaction. On the other hand, based on the narrow bandgap characteristics of Cu2SnS3, the system has good light-harvesting ability in the ultraviolet-visible-near-infrared band, exhibiting excellent photothermal conversion performance, accelerating the water evaporation rate, and realizing a liquid-solid phase seawater desalination reaction. In addition, the catalyst can be recovered through simple physical separation after the reaction, without causing secondary pollution, and the support material can be reused, saving reaction costs. This integrated system breaks through the limitations of traditional single functions and shows important application value in the field of CO2 resource utilization and seawater desalination co-production.

[0035] The above description is merely a specific embodiment of the present invention, but the scope of protection of the invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the invention.

Claims

1. An interface-integrated system for photo-driven CO2 reduction and seawater desalination coupling reaction, wherein the interface-integrated system is constructed using polyvinylidene fluoride (PVDF) membrane as the interface carrier material and 3DOM-TiO2 / Cu2SnS3 heterojunction as the photocatalyst and photothermal material, characterized in that: the system is prepared by reacting styrene (St), polyvinylpyrrolidone (PVP), potassium persulfate (K2S2O8), tetrabutyl titanate (TBOT), anhydrous ethanol (C2H6O), nitric acid (HNO3), copper chloride (CuCl2), stannous chloride (SnCl2), thiourea (CH4N2S), ethylene glycol ((CH2OH)2), N-methylpyrrolidone (NMP), and ammonia (NH3·H2O); the method for preparing the interface-integrated system is as follows: Step 1: Preparation of three-dimensional ordered polystyrene nanosphere templates Polystyrene nanospheres were prepared by emulsion polymerization. St, PVP and deionized water were added to a three-necked flask and stirred at room temperature for 10-200 min. Then, K2S2O8 was added as an initiator while stirring, and nitrogen gas was introduced into the reaction system to purge the air from the three-necked flask. Finally, the mixture was heated at 50-200 °C for 12-24 h to obtain a polystyrene nanosphere latex solution. The obtained latex solution was centrifuged multiple times to obtain a precipitate, which was then dried to obtain a three-dimensional ordered polystyrene nanosphere template. Step 2: Preparation of 3DOM-TiO2 catalyst TBOT, C2H6O and HNO3 were mixed evenly in a glass beaker by magnetic stirring. The prepared polystyrene nanosphere template was immersed in the above mixed solution and allowed to stand for 1-12 h. Then the template was taken out and dried overnight at room temperature. The dried template was placed in a crucible and calcined at 400-800 ℃ for 1-8 h with a heating rate of 1-10 ℃ / min to obtain three-dimensional ordered macroporous TiO2, i.e., 3DOM-TiO2. Step 3: Constructing a 3DOM-TiO2 / Cu2SnS3 heterojunction catalyst 3DOM-TiO2 / Cu2SnS3 heterojunction was prepared by a solvothermal method. CuCl2, SnCl2 and CH4N2S were added to (CH2OH)2 and stirred until completely dissolved. Then, a certain amount of 3DOM-TiO2 was added and stirring was continued for 10-60 min. The mixed solution was transferred to a stainless steel reactor and reacted at 100-300 ℃ for 6-24 h. After centrifugation, the product was washed 1-5 times with deionized water and ethanol, respectively, and finally dried in a vacuum oven for 6-12 h to obtain the 3DOM-TiO2 / Cu2SnS3 heterojunction catalyst. Step 4: Constructing the PVDF / 3DOM-TiO2 / Cu2SnS3 integrated system PVDF was dissolved in NMP and stirred for 30 min until completely dissolved. A certain amount of NH3·H2O was added and stirring was continued for 1-8 h. A certain amount of PVDF solution and 3DOM-TiO2 / Cu2SnS3 heterojunction catalyst were added to a centrifuge tube and sonicated for 10-60 min. The mixture was then poured into a petri dish and dried at room temperature to form a film. Finally, the petri dish was immersed in deionized water to peel off the film, thus obtaining the PVDF / 3DOM-TiO2 / Cu2SnS3 integrated system PVDF / 3DOM-TiO2 / CSS.

2. The interface integrated system for photocatalytic CO2 reduction and seawater desalination coupling reaction according to claim 1, characterized in that: In step 1, the amount of St is 5-50 g, the amount of PVP is 1-10 g, and the mass of K2S2O8 is 0.1-3 g.

3. The interface integrated system for photocatalytic CO2 reduction and seawater desalination coupling reaction according to claim 1, characterized in that: In step 2, the volume of TBOT is 5-50 mL, the volume of C2H6O is 5-30 mL, and the amount of HNO3 is 0.5-5 mL.

4. The interface integrated system for photocatalytic CO2 reduction and seawater desalination coupling reaction according to claim 1, characterized in that: In step 3, the mass of CuCl2 is 0.1-1.0 g, the mass of SnCl2 is 0.1-2.0 g, the mass of CH4N2S is 0.1-0.5 g, the volume of (CH2OH)2 is 30-100 mL, and the amount of 3DOM-TiO2 is 0.1-10 g.

5. The interface integrated system for photocatalytic CO2 reduction and seawater desalination coupling reaction according to claim 1, characterized in that: In step 4, the amount of PVDF used is 1-20 g, the volume of NMP is 30-200 mL, and the amount of NH3·H2O used is 1-5 mL; the amounts of PVDF solution and 3DOM-TiO2 / Cu2SnS3 heterojunction are 1-10 mL and 10-200 mg, respectively.

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