Preparation of a biomimetic photosynthetic membrane and method for light-regulated ion transport

Abstract

The application discloses a preparation method of a biomimetic photosynthetic membrane and light-regulated ion transport, and relates to the technical field of biomimetic photosynthetic membrane. The biomimetic photosynthetic membrane is prepared by introducing a conductive polymer into a MIL-101(Cr) porous structure, loading the conductive polymer on an AAO surface, and then constructing a MoS2 layer on one side of the conductive polymer@MIL-101(Cr) composite membrane. The membrane has asymmetry in structure, composition and charge distribution along the thickness direction, so that ions have different transmembrane transport capacities in opposite directions, thereby generating an ion rectification effect. Meanwhile, the MoS2 can form a light-responsive heterojunction with the conductive polymer, promote the separation and migration of photo-generated carriers under light, and form asymmetric accumulation of photo-generated charges and a transmembrane built-in electric field by using the single-side MoS2 structure, so as to drive the ion transport against the concentration gradient, realize a light-driven ion pump effect, and therefore the biomimetic photosynthetic membrane obtained by the application has ion rectification and light-driven ion pump functions.

Description

Technical Field

[0001] This invention relates to the field of biomimetic photosynthetic membrane technology, and in particular to a method for preparing a biomimetic photosynthetic membrane and for photo-regulated ion transport. Background Technology

[0002] Photosynthesis is a crucial energy conversion process in nature, enabling green plants, algae, and some bacteria to convert solar energy into chemical energy. Photosynthesis primarily occurs within photosynthetic membranes, which possess specific membrane structures. These membranes, through the coordinated regulation of transmembrane ion migration by membrane proteins with different functions, provide the energy basis for ATP synthesis and subsequent metabolic processes. Based on their ion transport mechanisms, membrane proteins are classified into ion channels and ion pumps. Ion channels, requiring no energy from the cell, achieve selective and directional ion transport by utilizing transmembrane concentration gradients. Ion pumps, on the other hand, require energy from the cell to drive ions to overcome their own electrochemical potential gradients, achieving transport against the concentration gradient. The two work together to enable the membrane system to both regulate the direction and flux of ion migration and actively establish and maintain transmembrane ion concentration gradients. However, because natural photosynthetic membranes rely on complex biological systems composed of proteins, lipids, and other bioactive components, they are highly sensitive to temperature, pH, and external environmental conditions, making direct application in practical production difficult. Therefore, inspired by the ion transport mechanisms of natural photosynthetic membranes, artificial biomimetic membranes are increasingly being used to simulate the ion channels and energy conversion processes of biological membranes.

[0003] In artificial biomimetic membrane systems, ion rectification is a crucial strategy for mimicking the selective transport behavior of natural ion channels. Existing artificial photosynthetic membranes, by controlling factors such as the geometry, chemical composition, and surface charge distribution of the membrane material, can create asymmetric ion transport environments on both sides of the membrane. This endows artificial nanochannels with the ability to regulate the direction and flux of ion migration, achieving directional transport similar to natural ion channels. For example, by constructing a hybrid structure of polypyrrole conductive polymer membrane and anodic alumina nanochannel, the asymmetry of membrane structure and surface charge can be utilized to achieve ion rectification. Simultaneously, to achieve light-driven ion migration similar to that of natural photosynthetic membranes, existing technologies introduce materials with photoresponsive properties into artificial biomimetic membrane systems. These materials utilize light-induced photogenerated carrier separation, charge redistribution, or local electric field changes to provide the driving force for ion transmembrane migration. For instance, anion-doped polypyrrole conductive polymer membranes can undergo charge state changes under light irradiation, thereby promoting ion migration along specific directions and realizing the conversion of light energy into ion electrochemical potential energy.

[0004] However, existing artificial biomimetic membrane systems typically focus on achieving a single function. Specifically, they rely on structural asymmetry or surface charge modulation to achieve ion rectification, but lack the ability for light-driven active ion migration. While photoresponsive membranes can utilize light energy to regulate ion transport, their ion selectivity and directional transport capabilities are limited, and their light energy conversion efficiency still needs improvement. Compared to the synergistic mechanism of ion channels and ion pumps in natural photosynthetic membranes, existing artificial membrane systems still struggle to simultaneously achieve selective rectified ion transport and light-driven active migration within the same membrane structure.

[0005] Therefore, developing a biomimetic photosynthetic membrane that can both achieve directional rectification and transport of ions and generate an effective driving force under illumination to promote ion transport against the concentration gradient and further improve the utilization efficiency of light energy is an urgent problem to be solved in the field of artificial photosynthetic membranes. Summary of the Invention

[0006] To address the aforementioned limitations of existing technologies, the present invention aims to provide a method for preparing a biomimetic photosynthetic membrane and for photo-regulated ion transport. This invention involves introducing a conductive polymer into a porous structure of MIL-101(Cr) and loading it onto an AAO surface. A MoS2 layer is then constructed on one side of the conductive polymer@MIL-101(Cr) composite membrane to obtain the biomimetic photosynthetic membrane. This membrane exhibits asymmetry in structure, composition, and charge distribution along its thickness direction, resulting in different transmembrane transport capabilities for ions in opposite directions, thus generating an ion rectification effect. MoS2 can form a photoresponsive heterojunction with the conductive polymer, promoting the separation and migration of photogenerated carriers under illumination. Furthermore, the asymmetric accumulation of photogenerated charges and the built-in electric field across the membrane, achieved by the single-sided MoS2 structure, drive ion transport against the concentration gradient, realizing a photo-driven ion pump effect. Therefore, the biomimetic photosynthetic membrane obtained by this invention possesses both ion rectification and photo-driven ion pump functions.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a biomimetic photosynthetic membrane, comprising the following steps: (1) Disperse MIL-101(Cr) powder uniformly in conductive polymer monomers, soak at room temperature, centrifuge, wash and dry to obtain conductive polymer monomers@MIL-101(Cr) composites; add oxidant solution to the above conductive polymer monomers@MIL-101(Cr) composites to carry out oxidation reaction, centrifuge and dry to obtain conductive polymers@MIL-101(Cr) composites. The conductive polymer monomer is one of pyrrole, thiophene, and aniline; the oxidant is FeCl3 and / or ammonium persulfate. (2) Disperse the conductive polymer @MIL-101(Cr) composite in a polyvinylidene fluoride solution to obtain a coating solution; coat it on one side of the AAO substrate to form a conductive polymer @MIL-101(Cr) film, and dry it to obtain a conductive polymer @MIL-101(Cr) / AAO heterostructure film. (3) MoS2 nanosheet dispersion was coated onto the conductive polymer@MIL-101(Cr) / AAO heterostructure by spin coating to form a MoS2 nanolayer, and then dried to obtain a biomimetic photosynthetic membrane.

[0008] Preferably, in step (1), during the synthesis of the conductive polymer monomer @MIL-101(Cr) complex, pyrrole is synthesized in the form of pure pyrrole; thiophene is synthesized in the form of thiophene solution with a concentration of 0.08-0.12 mol / L; and aniline is synthesized in the form of aniline solution with a concentration of 0.08-0.12 mol / L.

[0009] Preferably, in step (1), the ratio of MIL-101(Cr) powder to conductive polymer monomer is 0.05 g: (1.5-2.5) mL.

[0010] Preferably, in step (1), the soaking time is 70-75 hours.

[0011] As a preferred option, in step (1), the specific washing process is as follows: wash with deionized water 3-5 times.

[0012] Preferably, in step (1), the drying time is 20-30 hours.

[0013] Preferably, in step (1), the concentration of the oxidant solution is 0.05-1.0 mol / L.

[0014] Preferably, in step (1), the ratio of MIL-101(Cr) to the oxidant solution is (0.04-0.06) g: (4-6) mL.

[0015] Preferably, in step (1), the oxidation reaction is carried out at a temperature of 0-5℃ and a reaction time of 20-25h.

[0016] Preferably, in step (1), the drying temperature is 35-45℃ and the drying time is 10-15h.

[0017] Preferably, in step (2), the polyvinylidene fluoride solution is prepared by polyvinylidene fluoride powder and N-methylpyrrolidone at a material-to-liquid ratio of (0.15-0.20) g: (4.5-5.0) mL.

[0018] Preferably, in step (2), the ratio of the conductive polymer @MIL-101(Cr) composite to the polyvinylidene fluoride solution is (0.04-0.06) g: 2.5 mL.

[0019] Preferably, in step (2), the coating amount of the coating solution on the AAO substrate is 10-20 μL / cm. 2 The thickness of the conductive polymer@MIL-101(Cr) film is 17-18 μm.

[0020] Preferably, in step (3), the concentration of the MoS2 nanosheet dispersion is 0.5-1.5 mg / mL, which is prepared by mixing MoS2 nanosheets and deionized water.

[0021] Furthermore, the MoS2 nanosheets have a diameter of 300 nm and a thickness of 1.5 nm.

[0022] Preferably, in step (3), the spin coating process is performed at a speed of 3500-4500 r / min and a time of 25-35 s.

[0023] Preferably, in step (3), the thickness of the MoS2 nanolayer is 70-90 nm.

[0024] In a second aspect, the present invention provides a biomimetic photosynthetic membrane prepared by the above-described preparation method.

[0025] A third aspect of the present invention provides a method for photo-modulated ion transport, comprising the following steps: By irradiating the aforementioned biomimetic photosynthetic membrane with externally applied light, the ion rectification effect is achieved through the asymmetry of the membrane's structure, composition, and surface charge distribution. At the same time, the light irradiation induces the separation and migration of photogenerated charge carriers, resulting in an asymmetric charge distribution and built-in electric field on both sides of the biomimetic photosynthetic membrane, thereby realizing the light-driven ion pump effect.

[0026] The beneficial effects of this invention are: This invention constructs a conductive polymer@MIL-101(Cr) / AAO heterostructure by introducing a conductive polymer into the pores of a MOF material and coating it onto one side of an AAO substrate; then, MoS2 nanosheets are coated onto the conductive polymer@MIL-101(Cr) film side surface on the conductive polymer@MIL-101(Cr) / AAO heterostructure to obtain a biomimetic photosynthetic membrane.

[0027] Because the MoS2 nanolayer is only disposed on one side of the conductive polymer@MIL-101(Cr) / AAO heterostructure, the membrane exhibits asymmetry in structure, composition, and charge distribution along its thickness direction. When ions migrate across the membrane in opposite directions, they encounter different transport resistances, resulting in an ion rectification effect and enabling selective control of ion migration direction and flux. Simultaneously, MoS2 forms a photoresponsive heterostructure interface with the conductive polymers (polypyrrole, polyaniline, polythiophene), promoting the generation, separation, and interface migration of photogenerated carriers under illumination. Combined with the unilateral asymmetric structure, this facilitates asymmetric accumulation of photogenerated charges, constructing a built-in electric field across the membrane. This built-in electric field drives ions to transport against the concentration gradient from the low-concentration side to the high-concentration side, forming a photo-driven ion pump effect. Therefore, the biomimetic photosynthetic membrane constructed in this invention achieves synergistic integration of ion rectification and photo-driven ion pump functions within the same membrane system. It can both control the direction of ion migration across the membrane and utilize light energy to drive active ion transport, improving the efficiency of light energy utilization in the artificial photosynthetic membrane. Attached Figure Description

[0028] Figure 1 Structural characterization diagrams of the MIL-101(Cr) and PPy@MIL-101(Cr) complex in Example 1; wherein, A is an electron microscope image of MIL-101(Cr), B is an electron microscope image of the PPy@MIL-101(Cr) complex, C is an EDX image of the PPy@MIL-101(Cr) complex, and D is a pore size distribution diagram of the MIL-101(Cr) and PPy@MIL-101(Cr) complex; Figure 2 Scanning electron microscope image of the PPy@MIL-101(Cr) / AAO heterostructure film of Example 1; Figure 3 Cross-sectional scanning electron microscope image of the MoS2 / PPy@MIL-101(Cr) / AAO photosynthetic film of Example 1; Figure 4 High-magnification cross-sectional scanning electron microscope image of the MoS2 nanolayer in the MoS2 / PPy@MIL-101(Cr) / AAO photosynthetic film of Example 1; Figure 5 : Ion current-voltage curve of AAO substrate; Figure 6 Ion current-voltage curve of MoS2 / PPy@MIL-101(Cr) / AAO photosynthetic membrane in Example 1; Figure 7 : Schematic diagram of electronic energy level structure and beam carrier migration of MoS2 / PPy@MIL-101(Cr) / AAO photosynthetic film in Example 1; Figure 8: Diagram of a biomimetic photosynthetic membrane current testing device; Figure 9 : Ion current-time trajectory curve of MoS2 / PPy@MIL-101(Cr) / AAO photosynthetic membrane in Example 1 under alternating visible light; Figure 10 Examples 1 and 3 show the IV and It curves of the biomimetic photosynthetic membranes prepared in Examples 1 and 1-3. Specifically, A is the It curve of the TiO2 / MIL-101(Cr) / AAO photosynthetic membrane of Comparative Example 3, B is the IV curve of the TiO2 / MIL-101(Cr) / AAO photosynthetic membrane of Comparative Example 3, C is the It curve of the PPy@MIL-101(Cr) / AAO heterofilm of Comparative Example 1, and D is the It curve of the PPy@MIL-101(Cr) / AAO heterofilm of Comparative Example 1. E is the I-V curve of the AAO heterogeneous membrane, E is the I-V curve of the MoS2 / MIL-101(Cr) / AAO photosynthetic membrane of Comparative Example 2, F is the I-V curve of the MoS2 / MIL-101(Cr) / AAO photosynthetic membrane of Comparative Example 2, G is the I-V curve of the MoS2 / PPy@MIL-101(Cr) / AAO photosynthetic membrane of Example 1, and H is the I-V curve of the MoS2 / PPy@MIL-101(Cr) / AAO photosynthetic membrane of Example 1. Detailed Implementation

[0029] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0030] As described in the background section, ion rectification and ion pumps address different ion transport problems. If a biomimetic photosynthetic membrane only possesses ion rectification capabilities, it can only selectively regulate the direction and flux of ion migration across the membrane, making it difficult to actively establish or maintain a transmembrane ion concentration gradient. If it only possesses ion pump capabilities, it mainly solves the energy supply problem for transport against the concentration gradient, making it difficult to simultaneously achieve effective control over the direction of ion migration. Therefore, to more closely approximate the synergistic regulation of ion transport by ion channels and ion pumps in natural photosynthetic membranes, it is necessary to construct an artificial membrane that combines the capabilities of ion rectification and light-driven ion pumps. This membrane would be able to selectively regulate the direction of ion transport while also utilizing light energy to drive ions to overcome concentration gradients for active transport.

[0031] Based on this, the present invention provides a method for preparing a biomimetic photosynthetic membrane and for photo-regulated ion transport. A conductive polymer@MIL-101(Cr) composite material is constructed by in-situ introducing a conductive polymer into the porous structure of MIL-101(Cr), and then loaded onto the surface of an AAO substrate to obtain a conductive polymer@MIL-101(Cr) / AAO heterostructure membrane. Then, a MoS2 nanosheet layer is constructed on one side of the conductive polymer@MIL-101(Cr) composite membrane to form a MoS2 / conductive polymer@MIL-101(Cr) / AAO biomimetic photosynthetic membrane with asymmetric structure, composition, and charge distribution along the membrane thickness direction.

[0032] This invention creates an asymmetry in the structure, composition, and surface charge environment of a biomimetic photosynthetic membrane along its thickness direction by sequentially constructing a conductive polymer@MIL-101(Cr) composite layer and a MoS2 nanosheet layer on one side of an AAO substrate. Due to the differences in the pore structure, interfacial composition, and surface charge state on both sides of the membrane, ions experience different transport resistances and exhibit varying local ion enrichment and depletion behaviors when passing through the membrane from different directions. This results in different ion currents under the same magnitude but opposite directions of applied bias voltage, achieving direction-selective ion transmembrane transport, i.e., generating an ion rectification effect. Therefore, the ion rectification performance of this invention mainly originates from the asymmetry of the membrane structure and surface charge distribution, rather than simply relying on illumination.

[0033] This invention utilizes a conductive polymer, MIL-101(Cr), and MoS2 to construct a photoresponsive composite system, thereby endowing biomimetic photosynthetic films with the ability to actively drive ion transport. Specifically, the conductive polymer is introduced into the porous structure of MIL-101(Cr), forming numerous micro- and nano-scale composite interfaces between the conductive polymer and MIL-101(Cr), increasing the effective photoresponsive interface while maintaining ion transport channels. Then, MoS2 nanosheets are deposited on the surface of the conductive polymer@MIL-101(Cr) composite layer. The conductive polymer (such as PPy) is a p-type conductive polymer, and MoS2 is an n-type semiconductor; their contact forms a photoresponsive heterojunction, which can also form a pn-type heterojunction.

[0034] like Figure 7As shown, under illumination, the MoS2 / conductive polymer heterostructure promotes the separation and migration of photogenerated electrons and holes, reduces the recombination probability of photogenerated carriers, and thus improves the effective utilization efficiency of photogenerated charges. Meanwhile, since the MoS2 nanosheets are only disposed on one side of the conductive polymer@MIL-101(Cr) / AAO heterostructure, the film's photoresponse structure exhibits significant asymmetry. Illuminated carriers are difficult to form a symmetrical distribution on both sides of the film, instead resulting in an asymmetric accumulation of photogenerated charges along the film thickness direction. This creates a transmembrane potential difference and a built-in electric field, which can provide additional driving force for ion transmembrane migration. When there is an ion concentration difference across the membrane, under dark conditions, ions are mainly driven by the concentration gradient and spontaneously diffuse from the high concentration side to the low concentration side. After illumination, the photogenerated carriers generated at the MoS2 / conductive polymer photoresponsive heterojunction separate and migrate, and form a transmembrane built-in electric field with the help of the membrane's asymmetric structure. This field can overcome the spontaneous diffusion caused by the concentration gradient, change the net migration direction of ions, and drive ions to be transported against the concentration gradient from the low concentration side to the high concentration side, thereby generating a photo-driven ion pump effect and realizing the conversion of light energy into ion electrochemical potential energy.

[0035] In this invention, MoS2 primarily functions to broaden the photoresponse range and promote interfacial carrier transport. On one hand, MoS2 possesses a wide spectral response range, which enhances the visible light response of the biomimetic photosynthetic film, enabling the system to utilize incident light energy more fully. On the other hand, the two-dimensional nanosheet structure of MoS2 has a large interfacial contact area, facilitating the formation of a sufficiently photoresponsive heterojunction with conductive polymers. This provides an effective pathway for the separation and interfacial migration of photogenerated carriers, thereby improving the photoresponse performance and light energy utilization efficiency of the film material.

[0036] Therefore, the MoS2 / conductive polymer@MIL-101(Cr) / AAO biomimetic photosynthetic membrane constructed in this invention achieves two distinct yet complementary ion transport functions within the same membrane system: on the one hand, by utilizing the asymmetry of the membrane's structure, composition, and surface charge along the thickness direction, ions have different transmembrane migration capabilities in two opposite directions, thereby achieving ion rectification; on the other hand, by utilizing the photoresponsive heterojunction of MoS2 / conductive polymer to generate and separate photogenerated carriers under illumination, and by leveraging the asymmetric accumulation of photogenerated charges and the built-in electric field across the membrane formed by the single-sided MoS2 structure, ions are driven to overcome the concentration gradient for active transport, thereby realizing a photo-driven ion pump.

[0037] This invention also provides a method for photo-controlled ion transport, specifically: using light as an external energy input, the transmembrane migration behavior of ions is controlled by adjusting the photogenerated charge distribution in a MoS2 / conductive polymer@MIL-101(Cr) / AAO biomimetic photosynthetic membrane. Under lightless or dark conditions, the membrane's asymmetric pore structure and surface charge distribution result in ions exhibiting different transmembrane transport capabilities in opposite directions, thus demonstrating ion rectification characteristics. Under light, the photoresponsive heterojunction formed by MoS2 and the conductive polymer promotes the generation, separation, and migration of photogenerated carriers. The unilaterally arranged MoS2 nanosheets further cause asymmetric accumulation of photogenerated charges along the membrane thickness direction, thereby establishing a built-in electric field across the membrane. This built-in electric field can alter the local distribution and migration driving force of ions within the membrane, and when an ion concentration difference exists across the membrane, it drives ions to overcome natural diffusion and transport against the concentration gradient. Therefore, by controlling the application and removal of light, the photoresponsive control of the ion transmembrane transport state can be achieved.

[0038] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0039] The experimental materials used in the embodiments of this invention are all conventional experimental materials in the art and can be purchased through commercial channels.

[0040] In this invention, MIL-101(Cr) is prepared by the following method: 5g of Cr(NO3)3·9H2O and 2.1g of terephthalic acid were mixed and dissolved in 50mL of deionized water. While stirring, 1mL of 40% hydrofluoric acid was added dropwise. After ultrasonic oscillation for 30min, the mixture was transferred to a 100mL polytetrafluoroethylene-lined container and placed in a sealed stainless steel reactor. The reaction was carried out at 220℃ for 8h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged, and then washed 2-3 times alternately with hot DMF and anhydrous ethanol. After cooling, centrifugation, and washing, the mixture was transferred to a drying oven and dried at 130℃ for 12h to obtain MIL-101(Cr).

[0041] Example 1: (1) Weigh 0.05g of MIL-101(Cr) powder, disperse it evenly in 2mL of pyrrole, soak at room temperature for 72h, centrifuge, wash with deionized water 4 times, and dry for 24h to obtain Py@MIL-101(Cr) complex; add 5mL of 0.8mol / L FeCl3 solution to the above Py@MIL-101(Cr) complex, place it in an ice-water bath at 0℃ for 24h of oxidation reaction, centrifuge, and dry in a drying oven at 40℃ for 12h to obtain PPy@MIL-101(Cr) complex; (2) Mix polyvinylidene fluoride powder and N-methylpyrrolidone at a material-to-liquid ratio of 0.18 g: 4.8 mL to obtain a polyvinylidene fluoride solution; mix PPy@MIL-101(Cr) composite and polyvinylidene fluoride solution at a material-to-liquid ratio of 0.05 g: 2.5 mL to obtain a coating solution; Take 10 μL of coating solution and apply it to one side of the AAO substrate (0.5 cm × 1.5 cm) to form a PPy@MIL-101(Cr) film with a thickness of 17.5 μm. Dry to obtain a PPy@MIL-101(Cr) / AAO heterostructure film. (3) MoS2 nanosheets with a diameter of 300 nm and a thickness of 1.5 nm were mixed with deionized water to prepare a MoS2 nanosheet dispersion with a concentration of 1 mg / mL. Using spin coating, at a speed of 4000 r / min, it was coated onto the PPy@MIL-101(Cr) / AAO heterostructure membrane side of the PPy@MIL-101(Cr) membrane. The spin coating time was 30 s, forming a MoS2 nanolayer with a thickness of 80 nm. After drying, a biomimetic photosynthetic membrane was obtained, denoted as MoS2 / PPy@MIL-101(Cr) / AAO photosynthetic membrane.

[0042] Example 2: (1) Take 0.05g of MIL-101(Cr) powder, disperse it evenly in 1.5mL of 0.1mol / L aniline solution, soak it at room temperature for 70h, centrifuge it, wash it 4 times with deionized water, and dry it for 20h to obtain aniline@MIL-101(Cr) complex; add 4mL of 0.07mol / L ammonium persulfate solution to the above aniline@MIL-101(Cr) complex, place it in an ice-water bath at 0℃ for 20h for oxidation reaction, centrifuge it, and dry it in a drying oven at 35℃ for 15h to obtain PANI@MIL-101(Cr) complex; (2) Mix polyvinylidene fluoride powder and N-methylpyrrolidone at a material-to-liquid ratio of 0.15 g: 4.5 mL to obtain a polyvinylidene fluoride solution; mix PANI@MIL-101(Cr) composite and polyvinylidene fluoride solution at a material-to-liquid ratio of 0.04 g: 2.5 mL to obtain a coating solution; Take 10 μL of coating solution and apply it to one side of the AAO substrate (0.5 cm × 1.5 cm) to form a PANI@MIL-101(Cr) film. Dry the film to obtain a PANI@MIL-101(Cr) / AAO heterogeneous film. (3) MoS2 nanosheets with a diameter of 300 nm and a thickness of 1.5 nm were mixed with deionized water to prepare a MoS2 nanosheet dispersion with a concentration of 0.5 mg / mL. Using spin coating, at a speed of 3500 r / min, it was coated onto the PANI@MIL-101(Cr) / AAO heterostructure membrane side of PANI@MIL-101(Cr) membrane. The spin coating time was 25 s, forming a MoS2 nanolayer. After drying, a biomimetic photosynthetic membrane was obtained, denoted as MoS2 / PANI@MIL-101(Cr) / AAO photosynthetic membrane.

[0043] Example 3: (1) Take 0.05g of MIL-101(Cr) powder, disperse it evenly in 2.5mL of 0.1mol / L thiophene solution, soak it at room temperature for 75h, centrifuge it, wash it 4 times with deionized water, and dry it for 30h to obtain Th@MIL-101(Cr) complex; add 6mL of 0.2mol / L FeCl3 solution to the above Th@MIL-101(Cr) complex, place it in an ice-water bath at 5℃ for 25h oxidation reaction, centrifuge it, and dry it in a drying oven at 45℃ for 10h to obtain PTh@MIL-101(Cr) complex; (2) Mix polyvinylidene fluoride powder and N-methylpyrrolidone at a material-to-liquid ratio of 0.20 g: 5.0 mL to obtain a polyvinylidene fluoride solution; mix PTh@MIL-101(Cr) composite and polyvinylidene fluoride solution at a material-to-liquid ratio of 0.06 g: 2.5 mL to obtain a coating solution; Take 10 μL of coating solution and apply it to one side of the AAO substrate (0.5 cm × 1.5 cm) to form a PTh@MIL-101(Cr) film. Dry to obtain a PTh@MIL-101(Cr) / AAO heterogeneous film. (3) MoS2 nanosheets with a diameter of 300 nm and a thickness of 1.5 nm were mixed with deionized water to prepare a MoS2 nanosheet dispersion with a concentration of 1.5 mg / mL. Using spin coating, at a rotation speed of 4500 r / min, it was coated onto the PTh@MIL-101(Cr) / AAO heterostructure membrane side of the PTh@MIL-101(Cr) membrane. The spin coating time was 35 s, forming a MoS2 nanolayer. After drying, a biomimetic photosynthetic membrane was obtained, denoted as MoS2 / PTh@MIL-101(Cr) / AAO photosynthetic membrane.

[0044] Comparative Example 1: The difference between this comparative example and Example 1 is that MoS2 nanosheets were not used in the preparation of the biomimetic photosynthetic membrane.

[0045] The PPy@MIL-101(Cr) / AAO heterogeneous membrane was prepared according to the method in Example 1 and used as a biomimetic photosynthetic membrane.

[0046] Comparative Example 2: The difference between this comparative example and Example 1 is that polypyrrole was not used in the preparation of the biomimetic photosynthetic membrane. The specific preparation method is as follows: Polyvinylidene fluoride solution and MoS2 nanosheet dispersion were prepared according to the method in Example 1; Mix MIL-101(Cr) powder and polyvinylidene fluoride solution at a ratio of 0.05 g: 2.5 mL to obtain a coating solution; take 10 μL of the coating solution and apply it to one side of an AAO substrate (0.5 cm × 1.5 cm) to form a MIL-101(Cr) film, and dry it to obtain a MIL-101(Cr) / AAO film; MoS2 nanosheet dispersion was coated onto the MIL-101(Cr) / AAO membrane side at a spin coating speed of 4000 r / min for 30 s to form a MoS2 nanolayer. After drying, a biomimetic photosynthetic membrane was obtained, denoted as MoS2 / MIL-101(Cr) / AAO photosynthetic membrane.

[0047] Comparative Example 3: The difference between this comparative example and Comparative Example 2 is that TiO2 nanosheets are used instead of MoS2 nanosheets. The specific steps are as follows: MIL-101(Cr) powder and polyvinylidene fluoride solution were mixed at a ratio of 0.05 g: 2.5 mL to obtain a coating solution. 10 μL of the coating solution was taken and coated onto one side of an AAO substrate (0.5 cm × 1.5 cm) to form a MIL-101(Cr) film. The film was dried to obtain a MIL-101(Cr) / AAO film. TiO2 nanosheets and deionized water were mixed to prepare a TiO2 nanosheet dispersion with a concentration of 1 mg / mL. The dispersion was then coated onto the MIL-101(Cr) film side of the MIL-101(Cr) / AAO film by spin coating at a speed of 4000 r / min for 30 s to form a TiO2 nanolayer. The film was dried to obtain a biomimetic photosynthetic film, denoted as TiO2 / MIL-101(Cr) / AAO photosynthetic film.

[0048] Experimental Example 1: Structural Characterization 1. Electron microscopy analysis was performed on the MIL-101(Cr) powder and PPy@MIL-101(Cr) composite in Example 1. The results are as follows: Figure 1 As shown in A and B in the diagram.

[0049] Depend on Figure 1 As can be seen from A, MIL-101(Cr) has a smooth surface, a uniform octahedral structure, and particles with a size of approximately 1 μm. Figure 1As can be seen from B in the figure, the PPy@MIL-101(Cr) complex retains the octahedral morphology of MIL-101(Cr) and has the cauliflower-like morphology of PPy on the surface, indicating that PPy has successfully complexed with MIL-101(Cr).

[0050] 2. To further confirm the surface composition of the PPy@MIL-101(Cr) film, energy-dispersive X-ray diffraction analysis was performed on the PPy@MIL-101(Cr) composite. The results are as follows: Figure 1 As shown in C.

[0051] Depend on Figure 1 As can be seen from the C, nitrogen and chromium elements are uniformly distributed on the surface of the PPy@MIL-101(Cr) composite.

[0052] 3. Pore size analysis was performed on MIL-101(Cr) powder and PPy@MIL-101(Cr) composite, and the results are as follows: Figure 1 As shown in D in the diagram.

[0053] Depend on Figure 1 As can be seen from D, the MIL-101(Cr) material contains mesopores (22.0 Å, 19.5 Å). The pore size of the PPy@MIL-101(Cr) composite prepared after PPy doping is reduced, and the pores of 19.2 Å and 21.7 Å serve as the main pathways for ion passage.

[0054] 4. Electron microscopy analysis was performed on the PPy@MIL-101(Cr) / AAO heterostructure and MoS2 / PPy@MIL-101(Cr) / AAO photosynthetic membrane prepared in Example 1. The results are as follows: Figures 2-4 As shown.

[0055] Depend on Figure 2 It can be seen that the surface of the PPy@MIL-101(Cr) / AAO heterostructure film has a large number of octahedral particles, indicating that the MIL-101(Cr) crystal structure is well preserved during the composite process. Meanwhile, as mentioned earlier, the cauliflower-like morphology of PPy on the surface indicates that PPy was successfully loaded onto the MIL-101(Cr) surface, forming a PPy@MIL-101(Cr) composite structure.

[0056] Depend on Figure 3 As can be seen, the MoS2 / PPy@MIL-101(Cr) / AAO photosynthetic film exhibits a distinct layered structure. The black area at the top of the cross-section is the spin-coated MoS2 nanolayer, and the lower part is the PPy@MIL-101(Cr) / AAO film, with a relatively continuous overall interface. Further analysis of the MoS2 nanolayer corresponding to the black area reveals... Figure 4 As shown. By Figure 4As can be seen, the MoS2 nanolayers exhibit a layered morphology. These results indicate that MoS2 coats the surface of the PPy@MIL-101(Cr) film.

[0057] Experimental Example 2: Ion Rectification Performance Test At room temperature, the AAO substrate and the MoS2 / PPy@MIL-101(Cr) / AAO photosynthetic membrane prepared in Example 1 were respectively installed in a two-chamber electrolytic cell. 1 mM KCl was added to both chambers of the electrolytic cell as the electrolyte. Different transmembrane voltages (-2V, -1V, 0V, 1V, 2V) were applied, and ion current-voltage curves were obtained. The results are as follows: Figures 5-6 As shown.

[0058] Depend on Figure 5 It can be seen that, due to the uniform structure of the AAO substrate, its ion current-voltage curve is linear and does not show obvious ion rectification behavior.

[0059] Depend on Figure 6 As can be seen, this invention sequentially forms a PPy@MIL-101(Cr) film and a MoS2 nanolayer on one side of the AAO substrate surface, constructing a MoS2 / PPy@MIL-101(Cr) / AAO hybrid nanochannel. Compared to AAO films with a uniform pore structure, this hybrid nanochannel, due to the introduction of the PPy@MIL-101(Cr) composite layer, alters the surface chemical environment and ion transport interface of the AAO nanopores. Simultaneously, the unilaterally constructed MoS2 nanolayer creates asymmetry in the structure, composition, and surface charge distribution of the film along its thickness direction, resulting in different ion current responses in the MoS2 / PPy@MIL-101(Cr) / AAO photosynthetic film under the same magnitude but opposite bias voltage, exhibiting an ion rectification effect.

[0060] Experimental Example 3: Performance Test of Photo-Driven Ion Pump refer to Figure 8 A biomimetic photosynthetic membrane current testing device was constructed. Specifically, the biomimetic photosynthetic membrane (MoS2 / PPy@MIL-101(Cr) / AAO photosynthetic membrane) prepared in Example 1 was clamped and fixed in the middle of a two-chamber electrolytic cell, allowing ion transport between the solutions on both sides of the membrane to occur solely through the membrane. Ag / AgCl electrodes were placed in the electrolytes on both sides of the membrane to measure the transmembrane ion current. A black protective sleeve was used to shield the electrode area to prevent light from affecting the electrodes. During the test, the MoS2 nanolayer side of the MoS2 / PPy@MIL-101(Cr) / AAO photosynthetic membrane was designated as the high-concentration side, and 1 mM KCl solution was added. The AAO substrate side of the MoS2 / PPy@MIL-101(Cr) / AAO photosynthetic membrane was designated as the low-concentration side, and 0.9 mM KCl solution was added. Subsequently, a light intensity of 100 mW / cm² was used.2 MoS2 nanolayers were irradiated with visible light, and the current-time (It) response curves of the membrane before and after irradiation were recorded using a picoammeter to evaluate the light-driven ion pump performance of the biomimetic photosynthetic membrane. The results are as follows: Figure 9 As shown.

[0061] like Figure 9 As shown, under dark conditions, due to the KCl concentration gradient across the membrane, K + and Cl - Primarily driven by concentration gradient, diffusion migration occurs, and the membrane system exhibits a stable background current. Upon application of visible light, the membrane current changes significantly, specifically shifting from negative to positive, indicating that light irradiation can modulate the transmembrane ion current response. When light irradiation is removed, the membrane current returns to its dark-state level, suggesting that the change in ion migration direction originates from a photoinduced process, rather than being solely caused by concentration gradient or membrane structural asymmetry. These results demonstrate that the MoS2 / PPy@MIL-101(Cr) / AAO photosynthetic membrane can utilize light energy to regulate ion transmembrane migration, achieving a light-driven ion pump function.

[0062] Experimental Example 4: Comparative Experiment of Different Material Systems The PPy@MIL-101(Cr) / AAO heterostructure membrane prepared in Comparative Example 1, the MoS2 / MIL-101(Cr) / AAO photosynthetic membrane prepared in Comparative Example 2, the TiO2 / MIL-101(Cr) / AAO photosynthetic membrane prepared in Comparative Example 3, and the MoS2 / PPy@MIL-101(Cr) / AAO photosynthetic membrane prepared in Example 1 were used as samples, and their ion transport performance was tested. Ion transport performance included ion rectification performance and ion pumping performance, and the testing methods were the same as in Examples 2 and 3. The test results are as follows: Figure 10 As shown.

[0063] Depend on Figure 10It can be seen that the PPy@MIL-101(Cr) / AAO heterostructure film prepared in Comparative Example 1, the MoS2 / MIL-101(Cr) / AAO photosynthetic film prepared in Comparative Example 2, and the TiO2 / MIL-101(Cr) / AAO photosynthetic film prepared in Comparative Example 3 all exhibit certain ion rectification behavior, but no current direction reversal occurs under illumination. This indicates that single-component composite films cannot achieve an effective light-driven ion pumping effect. In contrast, the MoS2 / PPy@MIL-101(Cr) / AAO photosynthetic film prepared in this invention not only exhibits obvious ion rectification characteristics, but also achieves reversible control of the ion current direction under illumination, demonstrating a light-driven ion pumping effect. The results show that the ion rectification effect generated by the asymmetry of the structure, composition, and charge distribution of the MoS2 / PPy@MIL-101(Cr) / AAO photosynthetic film, and the light-driven effect generated by the MoS2 / PPy photoresponsive heterostructure interface, work synergistically to endow this biomimetic photosynthetic film with dual ion transport functions.

[0064] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a biomimetic photosynthetic membrane, characterized in that, Includes the following steps: (1) Disperse MIL-101(Cr) powder uniformly in conductive polymer monomers, soak at room temperature, centrifuge, wash and dry to obtain conductive polymer monomers@MIL-101(Cr) composites; add oxidant solution to the above conductive polymer monomers@MIL-101(Cr) composites to carry out oxidation reaction, centrifuge and dry to obtain conductive polymers@MIL-101(Cr) composites. The conductive polymer monomer is one of pyrrole, thiophene, and aniline; the oxidant is FeCl3 and / or ammonium persulfate. (2) Disperse the conductive polymer @MIL-101(Cr) composite in a polyvinylidene fluoride solution to obtain a coating solution; coat it on one side of the AAO substrate to form a conductive polymer @MIL-101(Cr) film, and dry it to obtain a conductive polymer @MIL-101(Cr) / AAO heterostructure film. (3) MoS2 nanosheet dispersion was coated onto the conductive polymer@MIL-101(Cr) membrane side of the conductive polymer@MIL-101(Cr) / AAO heterostructure by spin coating to form a MoS2 nanolayer, and dried to obtain a biomimetic photosynthetic membrane.

2. The method for preparing the biomimetic photosynthetic membrane as described in claim 1, characterized in that, In step (1), the ratio of MIL-101(Cr) powder to conductive polymer monomer is 0.05g:(1.5-2.5)mL; the soaking time is 70-75h.

3. The method for preparing the biomimetic photosynthetic membrane as described in claim 1, characterized in that, In step (1), the concentration of the oxidant solution is 0.05-1.0 mol / L; the ratio of MIL-101(Cr) to the oxidant solution is (0.04-0.06) g: (4-6) mL.

4. The method for preparing the biomimetic photosynthetic membrane as described in claim 1, characterized in that, In step (1), the reaction temperature is 0-5℃ and the reaction time is 20-25h during the oxidation reaction; the drying temperature is 35-45℃ and the drying time is 10-15h during the drying process.

5. The method for preparing the biomimetic photosynthetic membrane as described in claim 1, characterized in that, In step (2), the polyvinylidene fluoride solution is prepared by polyvinylidene fluoride powder and N-methylpyrrolidone at a material-to-liquid ratio of (0.15-0.20) g: (4.5-5.0) mL; the material-to-liquid ratio of conductive polymer @MIL-101(Cr) composite to polyvinylidene fluoride solution is (0.04-0.06) g: 2.5 mL.

6. The method for preparing the biomimetic photosynthetic membrane as described in claim 1, characterized in that, In step (2), the coating amount of the coating solution on the AAO substrate is 10-20 μL / cm. 2 The thickness of the conductive polymer@MIL-101(Cr) film is 17-18 μm.

7. The method for preparing the biomimetic photosynthetic membrane as described in claim 1, characterized in that, In step (3), the concentration of the MoS2 nanosheet dispersion is 0.5-1.5 mg / mL; the thickness of the MoS2 nanolayer is 70-90 nm; during spin coating, the rotation speed is 3500-4500 r / min and the time is 25-35 s.

8. The biomimetic photosynthetic membrane prepared by the preparation method according to any one of claims 1-7.

9. A method for photo-controlled ion transport, characterized in that, Includes the following steps: By irradiating the biomimetic photosynthetic membrane of claim 8 with externally applied light, the ion rectification effect is achieved through the asymmetry of the membrane's structure, composition, and surface charge distribution. At the same time, the light irradiation induces the separation and migration of photogenerated charge carriers, resulting in an asymmetric charge distribution and built-in electric field on both sides of the biomimetic photosynthetic membrane, thereby realizing the light-driven ion pump effect.

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