CN114284518A - Application of PMSA Composite Membranes Based on Interfacial Superassembly in Salt Gradient Energy Conversion - Google Patents

Abstract

The invention discloses the application of a PMSA composite membrane based on interface superassembly in salt gradient energy conversion. The PMSA composite membrane is used as an ion transport membrane to convert salt gradient energy into electrical energy. The PMSA composite membrane is prepared based on an interface superassembly strategy. of polyurea/mesoporous silica/anodized aluminum composite films. First, the PU/MS/AAO heteroconjunctiva was prepared by superassembly strategy, and then sandwiched in a self-made two-chamber semiconductive cell to test its salt gradient energy conversion performance. The modification of the PU layer endows the composite membrane with very good stability in water, leading to its great potential in applications involving water. In addition, the mesoporous silica layer contains abundant nano-sized negatively charged nanochannels, which form an asymmetric heterostructure with positively charged AAO nanochannels, which greatly reduces the concentration polarization of the salt gradient energy conversion process. Phenomenon. PMSA captures electrical energy from artificial fresh seawater, which has potential practical application value in the field of energy conversion.

Description

Application of PMSA Composite Membranes Based on Interfacial Superassembly in Salt Gradient Energy Conversion

technical field

The invention belongs to the field of energy conversion, and in particular relates to the application of a PMSA composite membrane obtained based on interface superassembly in salt gradient energy conversion.

Background technique

At present, nanofluidic devices have a wide range of applications in the fields of salt difference energy conversion, biosensing, logic gating, and ion screening due to their nano-sized charge channels. The materials currently used to construct nanochannels include zero-dimensional nanoparticles, such as PS spheres, MOF particles, etc., one-dimensional nanofibers, nanowires, nanotubes and other materials, two-dimensional graphene oxide, _Mxenes , and C3N4 and other two _- dimensional materials sheet material. However, the nanochannel structures composed of the above-mentioned materials are all obtained by random stacking of the above-mentioned materials, and there are problems such as high disorder, disordered pore structure, and uneven pore size distribution. In view of the above problems, it is necessary to explore the preparation of a membrane material with regular pore structure and pore size. Among them, mesoporous materials are widely used to construct nanofluidic devices for the capture of salt difference energy due to their size of 2-50 nm, regular pore structure and high specific surface area. However, inorganic-based nanochannel devices such as silicon oxide and aluminum oxide have poor mechanical properties due to their unbendable skeleton. In response to this problem, it is necessary to find a coating with high mechanical properties to improve the mechanical properties of mesoporous materials.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an application of a PMSA composite membrane obtained by interface superassembly in salt gradient energy conversion in order to solve the above problems.

The object of the present invention is achieved through the following technical solutions:

Based on the application of the PMSA composite membrane obtained by interfacial superassembly in the conversion of salt gradient energy, the PMSA composite membrane is used as an ion transport membrane to convert the salt gradient energy into electrical energy, wherein the PMSA composite membrane is prepared based on the interfacial superassembly strategy. of polyurea/mesoporous silica/anodized aluminum composite films.

Further, the PMSA composite membrane is used as an ion transport membrane to convert the salt gradient energy between freshwater and seawater into electrical energy. For example, 0.5M NaCl and 0.01M NaCl are used as test electrolyte solutions to simulate seawater and freshwater respectively. In the solution environment, the PMSA composite membrane has very good cation selectivity, which can selectively transport cations, generate electrostatic current, and then convert it into electrical energy. Preferably, the PU side of the PMSA composite membrane faces seawater.

Further, the PMSA composite membrane is prepared by the following method:

(1) An ordered mesoporous silicon oxide film was grown on the AAO substrate by the interfacial superassembly method;

(2) configure the water-oil phase solution for synthesizing the polyurea monomer;

(3) adding PEI dropwise to the surface of the MS/AAO film, and volatilizing the water to dryness;

(4) The TDI solution was added dropwise to the surface of MS/AAO containing PEI polymer chains, and the interfacial polymerization reaction between the amino group and isocyanate between the two phases occurred to form a dense polyurea film, and the PMSA composite film was obtained.

Further, step (1) specifically includes the following steps:

(1-1) adopt polymethyl methacrylate to carry out pore blocking treatment to AAO;

(1-2) spin-coating the polymethyl methacrylate solution onto the AAO substrate;

(1-3) The spin-coated PMMA/AAO film is dried to ensure that the PMMA penetrates into the AAO pores;

(1-4) Prepare a precursor solution of mesoporous silica and prepolymerize at 60°C;

(1-5) Preparation of F127 template agent solution;

(1-6) dropping the prepolymerized mesoporous silica into the F127 template solution, stirring at room temperature, to obtain the final mesoporous silica precursor solution;

(1-7) spin-coating the mesoporous silicon oxide precursor solution onto the plugged AAO substrate;

(1-8) Evaporation-induced self-assembly at 40 °C for 24 h and thermal polymerization at 100 °C for 24 h to obtain the final mesoporous silica/alumina (MS/AAO) composite film.

Further, the specific method of step (1-1) is as follows: 2.3-2.7g of polymethyl methacrylate (PMMA) is dissolved in 23ml-27ml of acetone solution, and heated and stirred at 40-45 ° C until dissolved;

Step (1-2) the spin coating speed is 3000-3500 rpm, and the spin coating time is 30-40 seconds;

In step (1-3), the spin-coated PMMA/AAO film was dried in a fume hood for two hours, and then placed in an oven at 200° C. for 5-6 hours;

The specific method of step (1-4) is as follows: preparing prepolymerized mesoporous silica oligomer, adding 2-2.2g of tetraethyl silicate to 10-12g of absolute ethanol and 1.0-1.5g of deionized In a mixed solution of water and 0.5-0.6g of 0.2M hydrochloric acid, prepolymerize at 60°C for 1h;

The specific method for preparing the F127 template agent solution in step (1-5) is: dissolving 0.8-1 g of F127 into 9-12 g of absolute ethanol, and ultrasonically dispersing and dissolving until clarification;

Step (1-7) Spin-coating 200-250 μl of the mesoporous silicon oxide precursor solution on the plugged AAO substrate, the spin-coating speed is 3000-3500 rpm, and the spin-coating time is 40-60 seconds.

Further, the specific method for preparing the water-oil phase solution for synthesizing the polyurea monomer in step (2) is: prepare 1.0-1.8w/v% polyethyleneimine (PEI) aqueous solution, mix 1.2-2.16mg of 50wt% PEI The solution was dissolved in 55-65ml of deionized water; then 0.3-0.8w/v% of 2,4-diisocyanate (TDI) was prepared, and about 0.18-0.48mg of TDI was weighed and dissolved in 55-65ml of In n-hexane, the prepared two solutions were placed in an oven at 60 °C.

Further, in step (3), 200-250 μL of PEI was added dropwise to the surface of the MS/AAO membrane, and the water was evaporated to dryness at 60° C.;

In step (4), 160-200 μL of TDI solution was added dropwise to the surface of MS/AAO containing PEI polymer chains, and the interfacial polymerization reaction between the amino group and isocyanate between the two phases occurred in an oven at 60° C. The reaction time was 1 min.

Further, the PMSA composite membrane was sandwiched in a two-chamber semi-conductivity cell to test its salt gradient energy conversion performance. During the test, the artificial fresh sea water solution was placed in the two-chamber conductivity cell, and then a picoammeter was used to detect ions under different resistances. transmit current.

Further, the PMSA composite membrane was sandwiched in a two-chamber conductivity cell, and Ag/AgCl electrode pads were used to connect the entire circuit, and a picoammeter was used as a detection device to monitor the magnitude of the current. Detect the magnitude of the current under different resistance conditions, and calculate the energy density according to the following formula:

Among them, P is the power density, I is the absolute value of the osmotic current, R is the size of the applied resistance, and S is the test area.

In the present invention, polyurea is used as the waterproof protective layer of mesoporous silica, and a PMSA composite membrane is prepared by adopting the dual strategies of interfacial superassembly and interfacial polymerization. Compared with MS/AAO, it has a hydrophobic outer surface and has very good performance in water. stability. In addition, it slows down the ion transport to a certain extent, so it can increase the cation selectivity of the PMSA composite membrane. Then, a self-made two-chamber conductivity cell and electrochemical methods are used to characterize the salt difference energy conversion performance of the PMSA composite membrane.

The present invention adopts mesoporous silica as the intermediate material to construct the PMSA composite membrane. The main reason is that it not only has a regular nano-channel structure and provides abundant ion transport channels, but also has abundant silanols that endow the composite membrane with rich negative charges. The field of ion transport has a wide range of application values. The invention adopts AAO as the substrate of the composite membrane, and has three functions: (1) as the substrate to further spin-coat to prepare mesoporous silicon oxide nanochannels; (2) it can provide abundant positive-charged nano-sized ion transport channels; (3) Asymmetric nanochannels are formed with silicon oxide nanochannels, which can effectively suppress the phenomenon of concentration polarization.

The invention adopts a self-made two-chamber conductivity cell for transmembrane ion transmission, and then converts the salt difference energy existing between fresh water and seawater into electrical energy, and has potential practical application value in the field of salt gradient energy conversion.

Description of drawings

Fig. 1 is the stable performance diagram of PMSA composite membrane ion transport;

Figure 2 is a graph of the ion transport properties of the PGA composite membrane under different concentrations of KCl, in which Figure 2(a) is the I-V curve diagram under different KCl concentrations; Figure 2(b) is the rectification ratio of the PMSA composite membrane at different concentrations. Figure; (c) is the conductivity diagram of PMSA composite membrane under different electrolyte concentrations;

Fig. 3 is the ion selectivity performance figure of the PMSA composite membrane prepared by the present invention;

4 is a schematic diagram of ion transport of PMSA in different concentration directions and voltage directions;

Figure 5 is a comparison chart of the salt difference energy capture performance of PMSA composite membrane and different concentration gradient configurations, wherein Figure 5(a) is the I-V comparison chart of PMSA composite membrane under different concentration directions; (b) is different Contrast graph of current density under different resistance conditions in the concentration direction; (c) is the energy density comparison graph of PMSA composite film in different concentration directions under different resistance conditions; (d) is the comparison graph of PMSA composite film in different concentrations Comparison of the maximum energy density in the differential direction.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

Example 1

The ion transport performance of PMSA composite membrane was tested by electrochemical method. The specific operation steps are as follows:

Step 1: The first step is to grow an ordered mesoporous silicon oxide film on the AAO substrate by using the interfacial super-assembly method;

(1) Before preparing MS, firstly use polymethyl methacrylate to block the pores of AAO. The specific method is to dissolve 2.5g of polymethyl methacrylate (PMMA) into 25ml of acetone solution, 40-45 ℃ heated and stirred until dissolved;

(2) spin-coating the polymethyl methacrylate solution on the AAO substrate afterwards, the spin-coating speed is 3500 revs, and the spin-coating time is 30 seconds;

(3) Dry the spin-coated PMMA/AAO film in a fume hood for two hours, and then place it in an oven at 200 °C for 6 hours to ensure that PMMA can penetrate into the AAO pores, thereby playing a role in blocking pores;

(4) After preparing the precursor solution of mesoporous silica, firstly prepare the prepolymerized mesoporous silica oligomer, add 2.08g of tetraethyl silicate to 12g of absolute ethanol and 1.0g of deionized water and 0.5g of 0.2M hydrochloric acid mixed solution, prepolymerized at 60℃ for 1h;

(5) prepare F127 template agent solution: dissolve the F127 of 0.9g in the absolute ethanol of 10g, disperse ultrasonically and dissolve to clarification;

(6) 8 g of prepolymerized tetraethyl silicate was slowly added dropwise to the F127 template solution, and stirred at room temperature for 1 h to obtain the final mesoporous silica precursor solution;

(7) After that, spin-coat 200 μl of the mesoporous silicon oxide precursor solution on the AAO substrate that blocks the pores, the spin-coating speed is 3000 rpm, and the spin-coating time is 40 seconds;

(8) Afterwards, the final mesoporous silica/alumina (MS/AAO) composite film can be obtained by evaporation-induced self-assembly at 40°C for 24h and thermal polymerization at 100°C for 24h;

Step 2: Then prepare the water-oil phase solution for synthesizing the polyurea monomer: firstly, prepare 1.5w/v% polyethyleneimine (PEI) aqueous solution, and dissolve 1.8mg of 50wt% PEI solution in 60ml of deionized water ; Then prepare 0.5w/v% of 2,4-diisocyanate (TDI), weigh about 0.3mg of TDI and dissolve it in 60ml of n-hexane, and place the prepared two solutions in a 60°C in the oven;

Step 3: After that, first drop 200 μL of PEI onto the surface of the MS/AAO membrane, and wait for it to volatilize the water to dryness at 60°C;

Step 4: After that, 200 μL of TDI solution was added dropwise to the surface of MS/AAO containing PEI polymer chains, and the interfacial polymerization reaction between the amino group and isocyanate between the two phases occurred in an oven at 60 °C, and the reaction time was 1 min, resulting in a dense Polyurea film;

Step 5: The final PMSA composite membrane with high mechanical properties is obtained.

Step 6: Then build the ion transport equipment: sandwich the PMSA composite membrane in a self-made two-chamber conductivity cell, then use Ag/AgCl electrode pieces to connect the entire circuit, and a picoammeter is used as a detection device to monitor the size of the current, in which the resistance box is connected to In the whole circuit, the electrolyte solutions are 0.5M and 0.01M sodium chloride respectively, of which 0.5M sodium chloride is on the polyurea side, and a picoammeter is used to detect the current under different resistance conditions, among which the applied voltage value is 0, and then calculate the energy density calculation according to the following formula:

Example 2

The ion transport performance of PMSA composite membrane was tested by electrochemical method. The specific operation steps are as follows:

Step 1: The first step is to grow an ordered mesoporous silicon oxide film on the AAO substrate by using the interfacial super-assembly method;

(1) Before preparing MS, firstly use polymethyl methacrylate to block the pores of AAO. The specific method is to dissolve 2.3 g of polymethyl methacrylate (PMMA) into 23 ml of acetone solution, 40-45 ℃ heated and stirred until dissolved;

(2) spin-coating the polymethyl methacrylate solution on the AAO substrate afterwards, the spin-coating speed is 3000 revs, and the spin-coating time is 35 seconds;

(3) Dry the spin-coated PMMA/AAO film in a fume hood for two hours, and then place it in an oven at 200°C for 5 hours to ensure that PMMA can penetrate into the AAO pores, thereby blocking the pores;

(4) After preparing the precursor solution of mesoporous silica, firstly prepare the prepolymerized mesoporous silica oligomer, add 2.08g of tetraethyl silicate to 12g of absolute ethanol and 1.0g of deionized water and 0.5g of 0.2M hydrochloric acid mixed solution, prepolymerized at 60℃ for 1h;

(5) F127 template agent solution is prepared: 0.8g of F127 is dissolved in 9g of dehydrated alcohol, and ultrasonic dispersion is dissolved to clarification;

(6) 8 g of prepolymerized tetraethyl silicate was slowly added dropwise to the F127 template solution, and stirred at room temperature for 1 h to obtain the final mesoporous silica precursor solution;

(7) After that, spin-coat 200 μl of the mesoporous silicon oxide precursor solution on the AAO substrate that blocks the pores, the spin-coating speed is 3000 rpm, and the spin-coating time is 40 seconds;

(8) Afterwards, the final mesoporous silica/alumina (MS/AAO) composite film can be obtained by evaporation-induced self-assembly at 40°C for 24h and thermal polymerization at 100°C for 24h;

Step 2: Then prepare the water-oil phase solution for synthesizing the polyurea monomer: firstly, prepare 1.5w/v% polyethyleneimine (PEI) aqueous solution, and dissolve 1.8mg of 50wt% PEI solution in 60ml of deionized water ; Then prepare 0.5w/v% of 2,4-diisocyanate (TDI), weigh about 0.3mg of TDI and dissolve it in 60ml of n-hexane, and place the prepared two solutions in a 60°C in the oven;

Step 3: After that, first drop 200 μL of PEI onto the surface of the MS/AAO membrane, and wait for it to volatilize the water to dryness at 60°C;

Step 4: After that, 200 μL of TDI solution was added dropwise to the surface of MS/AAO containing PEI polymer chains, and the interfacial polymerization reaction between the amino group and isocyanate between the two phases occurred in an oven at 60 °C, and the reaction time was 1 min, resulting in a dense Polyurea film;

Step 5: The final PMSA composite membrane with high mechanical properties is obtained.

Step 6: Then build the ion transport equipment: sandwich the PMSA composite membrane in a self-made two-chamber conductivity cell, then use Ag/AgCl electrode pieces to connect the entire circuit, and a picoammeter is used as a detection device to monitor the size of the current, in which the resistance box is connected to In the whole circuit, the electrolyte solutions are 1M and 0.01M sodium chloride respectively, of which 0.5M sodium chloride is on the polyurea side. A picoammeter is used to detect the current under different resistance conditions, and the applied voltage is 0, and then calculate the energy density according to the formula.

Example 3

The ion transport performance of PMSA composite membrane was tested by electrochemical method. The specific operation steps are as follows:

Step 1: The first step is to grow an ordered mesoporous silicon oxide film on the AAO substrate by using the interfacial super-assembly method;

(1) Before preparing MS, firstly, polymethyl methacrylate was used to block the pores of AAO, and the specific method was to dissolve 2.7g of polymethyl methacrylate (PMMA) into 27ml of acetone solution, 40-45 ℃ heated and stirred until dissolved;

(2) spin-coating the polymethyl methacrylate solution on the AAO substrate afterwards, the spin-coating speed is 3500 revs, and the spin-coating time is 30 seconds;

(3) Dry the spin-coated PMMA/AAO film in a fume hood for two hours, and then place it in an oven at 200°C for 5 hours to ensure that PMMA can penetrate into the AAO pores, thereby blocking the pores;

(4) Then prepare the precursor solution of mesoporous silica, firstly prepare the prepolymerized mesoporous silica oligomer, add 2.2g of tetraethyl silicate to 12g of absolute ethanol and 1.0g of deionized water and 0.5g of 0.2M hydrochloric acid mixed solution, prepolymerized at 60℃ for 1h;

(5) prepare F127 template agent solution: dissolve the F127 of 0.9g in the absolute ethanol of 10g, disperse ultrasonically and dissolve to clarification;

(6) 8 g of prepolymerized tetraethyl silicate was slowly added dropwise to the F127 template solution, and stirred at room temperature for 1 h to obtain the final mesoporous silica precursor solution;

(7) After that, spin-coat 200 μl of the mesoporous silicon oxide precursor solution on the AAO substrate that blocks the pores, the spin-coating speed is 3000 rpm, and the spin-coating time is 40 seconds;

(8) Afterwards, the final mesoporous silica/alumina (MS/AAO) composite film can be obtained by evaporation-induced self-assembly at 40°C for 24h and thermal polymerization at 100°C for 24h;

Step 2: Then prepare the water-oil phase solution for synthesizing the polyurea monomer: firstly, prepare 1.5w/v% polyethyleneimine (PEI) aqueous solution, and dissolve 1.8mg of 50wt% PEI solution in 60ml of deionized water ; Then prepare 0.5w/v% of 2,4-diisocyanate (TDI), weigh about 0.3mg of TDI and dissolve it in 60ml of n-hexane, and place the prepared two solutions in a 60°C in the oven;

Step 3: After that, first drop 200 μL of PEI onto the surface of the MS/AAO membrane, and wait for it to volatilize the water to dryness at 60°C;

Step 4: After that, 200 μL of TDI solution was added dropwise to the surface of MS/AAO containing PEI polymer chains, and the interfacial polymerization reaction between the amino group and isocyanate between the two phases occurred in an oven at 60 °C, and the reaction time was 1 min, resulting in a dense Polyurea film;

Step 5: The final PMSA composite membrane with high mechanical properties is obtained.

Step 6: Then build the ion transport equipment: sandwich the PMSA composite membrane in a self-made two-chamber conductivity cell, then use Ag/AgCl electrode pieces to connect the entire circuit, and a picoammeter is used as a detection device to monitor the size of the current, in which the resistance box is connected to In the whole circuit, the electrolyte solutions are 2M and 0.01M sodium chloride, of which 0.5M sodium chloride is on the polyurea side. A picoammeter is used to detect the current under different resistance conditions, and the applied voltage is 0, and then calculate the energy density calculation according to the following formula:

The following takes Example 1 as an example to test the performance of the PMSA composite membrane

FIG. 1 is a graph showing the ion transport stability performance of the PMSA composite membrane prepared by the method of interfacial superassembly and interfacial polymerization in Example 1. The first is to sandwich the PMSA composite membrane in the middle of a self-made two-chamber conductivity cell, then add 0.1MKCl solution at both ends, apply potentials in different directions, and then test the currents in different potential directions, you can see the positive and negative potential conditions after different cycles , the PMSA composite film can still maintain a very good current stability performance, which is due to the presence of PU that increases the mechanical stability of the PMSA composite film.

Figure 2 is a graph of the ion transport properties of the PMSA composite membrane prepared in Example 1. Figure 2(a) is the IV curve of the PMSA composite membrane under different concentrations of KCl, and (b) is the rectification comparison under different electrolyte concentrations. Figure, where the rectification ratio is calculated by the formula f=I _+1.4V /I _-1.4V . (c) is the conductance value of the PMSA composite membrane at different concentrations. The specific implementation is to add KCl solutions of different concentrations to the two-chamber conductivity cells respectively, then test the IV curves under different concentrations of KCl, and calculate the slope to obtain the final Conductivity of PMSA composite membranes at different concentrations.

Cation Selectivity Test of PMSA Composite Membrane

The PMSA composite membrane was sandwiched in a two-chamber conductivity cell, and electrolyte solutions with different 10 ^-4 M KCl and 1 M KCl concentrations were added, respectively, and then the IV curves were scanned at +2V and -2V. When the PU side is faced with 1M KCl, under this concentration condition, the transport of the electrolyte solution is mainly from the polyurea end to the AAO end, and the current generated at +2V is mainly due to the transport of potassium ions , the current generated at a voltage of -2V is attributed to chloride ion transport, as shown in the red curve in Figure 3. It can be seen that the voltage of +2V is much higher than the voltage of -2V, which indicates that more potassium ions are transferred from the PU side to the AAO side than chloride ions, indicating that the membrane is cation-selective. When changing the direction of the concentration difference, it is mainly due to the transmission of chloride ions under the condition of +2V voltage, and the transmission of potassium ions under the voltage of -2V. Since the current of -2V is much higher than that of +2V, it is further explained The PMSA composite membrane as a whole showed very good cation selectivity. Among them, Figure 4 depicts the schematic diagram of ion transport under different concentration and different voltage conditions.

Test of Salt Difference Energy Conversion Performance of PMSA Composite Membrane

Figure 5 is a graph of the salt difference energy conversion performance of the PMSA composite membrane. The salt difference energy conversion ability of PMSA composite membrane is mainly tested under the condition of fresh seawater. Tests were carried out under two different concentration configurations, one is PU facing seawater (0.5MNaCl), the other is AAO facing seawater, and the salt difference energy of PMSA composite membrane was recorded under the two concentrations respectively. conversion performance. Figure 5a is the I-V plot under two concentration conditions. It can be seen that when the PU side faces seawater, the I-V has a higher slope, which indicates that more ion flow can be generated at this concentration. ; Figure 5b compares the current densities of the two concentrations under different external resistances. Consistent with 5a, the PU side has a higher current density when it faces seawater; the corresponding Figure 5c shows that the higher energy density is also When the PU is faced with seawater, Figure 5d finally summarizes that when the PU faces seawater, the PMSA composite membrane can achieve the highest energy density and has the highest salt difference energy conversion performance.

The foregoing description of the embodiments is provided to facilitate understanding and use of the invention by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein can be applied to other embodiments without inventive step. Therefore, the present invention is not limited to the above-mentioned embodiments, and improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should all fall within the protection scope of the present invention.

Claims (9)

1. the application of the PMSA composite membrane obtained based on interface superassembly in salt gradient energy conversion, it is characterized in that, PMSA composite membrane is used as ion transport membrane for converting salt gradient energy into electrical energy, wherein, described PMSA composite membrane is based on Polyurea/mesoporous silica/anodized alumina composite films prepared by an interfacial superassembly strategy. 2. the application of the PMSA composite membrane obtained based on interface superassembly according to claim 1 in salt gradient energy conversion, it is characterized in that, described PMSA composite membrane is used as ion transport membrane for the salt between freshwater and seawater Gradient energy is converted into electrical energy. 3. the application of the PMSA composite membrane obtained based on interface superassembly according to claim 1 in salt gradient energy conversion, it is characterized in that, described PMSA composite membrane is prepared by the following method: (1) An ordered mesoporous silicon oxide film was grown on the AAO substrate by the interfacial superassembly method; (2) configure the water-oil phase solution for synthesizing the polyurea monomer; (3) adding PEI dropwise to the surface of the MS/AAO film, and volatilizing the water to dryness; (4) The TDI solution was added dropwise to the surface of MS/AAO containing PEI polymer chains, and the interfacial polymerization reaction between the amino group and isocyanate between the two phases occurred to form a dense polyurea film, and the PMSA composite film was obtained. 4. the application of the PMSA composite membrane obtained based on interface superassembly according to claim 3 in salt gradient energy conversion, is characterized in that, step (1) specifically comprises the following steps: (1-1) adopt polymethyl methacrylate to carry out pore blocking treatment to AAO; (1-2) spin-coating the polymethyl methacrylate solution onto the AAO substrate; (1-3) The spin-coated PMMA/AAO film is dried to ensure that the PMMA penetrates into the AAO pores; (1-4) Prepare a precursor solution of mesoporous silica and prepolymerize at 60°C; (1-5) Preparation of F127 template agent solution; (1-6) dropping the prepolymerized mesoporous silica into the F127 template solution, stirring at room temperature, to obtain the final mesoporous silica precursor solution; (1-7) spin-coating the mesoporous silicon oxide precursor solution onto the plugged AAO substrate; (1-8) Evaporation-induced self-assembly at 40 °C for 24 h and thermal polymerization at 100 °C for 24 h to obtain the final mesoporous silica/alumina (MS/AAO) composite film. 5. the application of the PMSA composite membrane obtained based on interface superassembly according to claim 4 in salt gradient energy conversion, is characterized in that, The specific method of step (1-1) is as follows: 2.3-2.7g of polymethyl methacrylate (PMMA) is dissolved in 23ml-27ml of acetone solution, and heated and stirred at 40-45° C. until dissolved; Step (1-2) the spin coating speed is 3000-3500 rpm, and the spin coating time is 30-40 seconds; In step (1-3), the spin-coated PMMA/AAO film was dried in a fume hood for two hours, and then placed in an oven at 200° C. for 5-6 hours; The specific method of step (1-4) is as follows: preparing prepolymerized mesoporous silica oligomer, adding 2-2.2g of tetraethyl silicate to 10-12g of absolute ethanol and 1.0-1.5g of deionized In a mixed solution of water and 0.5-0.6g of 0.2M hydrochloric acid, prepolymerize at 60°C for 1h; The specific method for preparing the F127 template agent solution in step (1-5) is: dissolving 0.8-1 g of F127 into 9-12 g of absolute ethanol, and ultrasonically dispersing and dissolving until clarification; Step (1-7) Spin-coating 200-250 μl of the mesoporous silicon oxide precursor solution on the plugged AAO substrate, the spin-coating speed is 3000-3500 rpm, and the spin-coating time is 40-60 seconds. 6. the application in the salt gradient energy conversion of the PMSA composite membrane that obtains based on interface superassembly according to claim 3, is characterized in that, the concrete method of the water-oil phase solution of step (2) configuration synthetic polyurea monomer is: Prepare 1.0-1.8w/v% polyethyleneimine (PEI) aqueous solution, dissolve the PEI solution in deionized water; then prepare 2,4-diisocyanate (TDI), weigh TDI and dissolve it in n-hexane , put the prepared two solutions in an oven at 60 °C. 7. the application of the PMSA composite membrane obtained based on interface superassembly according to claim 3 in salt gradient energy conversion, it is characterized in that, in step (3), the PEI of 200-250 μL is dripped on MS/AAO membrane surface , wait for it to evaporate the water to dryness at 60°C; In step (4), 160-200 μL of TDI solution was added dropwise to the surface of MS/AAO containing PEI polymer chains, and the interfacial polymerization reaction between the amino group and isocyanate between the two phases occurred in an oven at 60° C. The reaction time was 1 min. 8. the application of the PMSA composite membrane obtained based on interface superassembly according to claim 1 and 2 in salt gradient energy conversion, it is characterized in that, described PMSA composite membrane is sandwiched in two-chamber semi-conductivity cell to test its salt gradient In the test process, the artificial fresh sea water solution was placed in a two-chamber conductivity cell, and then a picoammeter was used to detect the ion transport current under different resistances. 9. the application of the PMSA composite membrane obtained based on interface superassembly according to claim 8 in the salt gradient energy conversion, it is characterized in that, PMSA composite membrane is clamped in two-chamber conductivity cells, using Ag/AgCl electrode sheet to connect In the whole circuit, a picoammeter is used as a detection device to monitor the magnitude of the current. The resistance box is connected to the entire circuit. The picoammeter is used to detect the magnitude of the current under different resistance conditions, and the energy density is calculated according to the following formula:

Among them, P is the power density, I is the absolute value of the osmotic current, R is the size of the applied resistance, and S is the test area.

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