Photo-thermal driving type water-electricity co-production composite material as well as preparation method and application thereof

Abstract

The invention discloses a photo-thermal driving type water-electricity co-production composite material as well as a preparation method and application thereof. The composite material comprises a matrix formed by sodium alginate, calcium lignosulphonate and polypyrrole, and a network structure is formed through cross-linking reaction and directional freezing and used for loading lithium chloride. A calcium lignosulphonate cross-linked sodium alginate system improves the rigidity of the material, collapse of pore channels in the adsorption-desorption cycle process is avoided, rich aromatic rings and pi-pi conjugated structures cooperate with polypyrrole to perform photothermal conversion, and meanwhile, the surface activity of calcium lignosulphonate is beneficial to promoting uniform distribution of moisture, so that the photothermal conversion efficiency is improved. Therefore, the adsorption efficiency of the photo-thermal composite material is accelerated. The composite material has excellent moisture absorption performance in a wide relative humidity range, and water collection and power generation are realized at the same time. The method is wide in raw material source, low in cost and suitable for large-scale production. The composite material has a wide application prospect in atmospheric water collection, is especially suitable for drought, water-deficient and power-deficient areas, and shows high application potential.

Description

Technical Field

[0001] The present invention belongs to the technical fields of moisture-absorbing materials, new energy, and comprehensive utilization of water resources, and particularly relates to a photothermal-driven water-electricity co-production composite material, a preparation method thereof, and an application thereof. Background Art

[0002] The problem of global water resource shortage is becoming increasingly severe. Especially in arid and semi-arid regions with scarce water resources, it is particularly urgent to develop efficient water collection technologies. Against this background, water collection technologies driven by solar energy have emerged. With their advantages of being clean, sustainable, and low-energy-consuming, they have become a new type of fresh water capture technology that can meet the dual needs of efficiently obtaining water resources and sustainable energy development.

[0003] Traditional fog capture technologies and compression cooling water collection technologies have certain limitations in terms of geographical conditions and desorption energy consumption. To solve these problems, researchers have begun to explore new composite moisture-absorbing materials. Combining a matrix material with a moisture absorbent (such as LiCl, CaCl2, etc.) provides a stable support structure for the moisture absorbent. In addition, the active groups on the surface of the matrix material form hydrogen bonds with water molecules, and cooperate with the moisture-absorbing salt to enhance the moisture-absorbing performance of the material. At the same time, the porous structure of the matrix material helps the rapid diffusion and adsorption of water molecules, further improving the water collection efficiency. The technology with the application publication number CN 118344653A discloses a preparation method of a porous photothermal composite material. By sequentially adding a bacterial cellulose dispersion liquid and a graphene oxide suspension liquid into an aqueous sodium alginate solution, standing in a mold, and freeze-drying to obtain a gel precursor, further soaking in CaCl2 for cross-linking, and then impregnating in an LiCl solution, and performing secondary freeze-drying to obtain a photothermal composite moisture-absorbing material.

[0004] The above preparation method and the obtained composite material have the following problems: First, the moisture absorption kinetics is slow, and it is difficult to achieve rapid water collection; second, the durability problem of the carbon-based photothermal material and the relatively low photothermal conversion temperature, and structural degradation will occur under high temperature and long-term light conditions; third, the light absorption range is limited, and the absorption of light is mainly concentrated in the visible light region, and the absorption of infrared light is weak, and the light source cannot be fully utilized; fourth, the preparation process is complex, time-consuming, and the price of GO is expensive, which does not conform to the concept of green environmental protection and is difficult to achieve large-scale industrial production. Therefore, developing efficient and low-energy-consuming composite moisture-absorbing materials is of great significance for solving the global water resource shortage problem. By optimizing the composition and structure of the materials, efficient and low-cost fresh water acquisition can be realized, and it is expected to provide a sustainable water and electricity acquisition solution for remote arid regions. Summary of the Invention

[0005] To solve the disadvantages and deficiencies of the prior art, the primary object of the present invention is to provide a preparation method of a photothermal-driven water-electricity co-production composite material.

[0006] In view of the common problem of shortage of water and electricity resources in remote areas, the present invention innovatively constructs an integrated system of adsorption-desorption-thermoelectric conversion based on biomass-derived porous materials.

[0007] The present invention uses sodium alginate (SA) as the substrate, calcium lignosulfonate (CLS) as the cross-linking agent, and constructs the matrix by means of the chelation of metal ions. Calcium lignosulfonate is derived from paper-making waste liquor. A variety of hydrophilic groups in its molecular structure can effectively absorb and retain water, and its surface activity helps to promote the uniform distribution of water, thus accelerating the adsorption kinetics of the photothermal composite material. In addition, the introduction of polypyrrole (PPy) significantly improves the light absorption performance of the photothermal composite material, further increases the surface temperature of the composite material, accelerates the desorption kinetics, and realizes efficient water collection and power generation at the same time. The water and electricity co-production system can make full use of the waste heat generated during the water collection process, as a supplement to new energy technologies, and alleviate the shortage of water and electricity in remote areas.

[0008] Another object of the present invention is to provide a photothermal-driven water-electricity co-production composite material prepared by the above preparation method.

[0009] The solar-driven water-electricity co-production material provided by this application includes a matrix and a hygroscopic inorganic salt compounded in the matrix. Among them, the matrix raw materials include a three-dimensional interpenetrating network formed by cross-linking sodium alginate, polypyrrole and calcium lignosulfonate.

[0010] Another object of the present invention is to provide the application of the above-mentioned photothermal-driven water-electricity co-production composite material.

[0011] The object of the present invention is achieved by the following technical solutions:

[0012] A preparation method of a photothermal-driven water-electricity co-production composite material includes the following steps:

[0013] (1) Pyrrole is polymerized under the initiation of an initiator to obtain polypyrrole;

[0014] (2) After polypyrrole and sodium alginate (SA) are mixed evenly in water, a calcium lignosulfonate (CLS) solution is added for sufficient cross-linking reaction, followed by directional freezing and freeze-drying to obtain a gel precursor;

[0015] (3) The gel precursor is soaked in a LiCl solution to load LiCl and then dried to obtain a photothermal-driven water-electricity co-production composite material.

[0016] Preferably, the initiator in step (1) is ammonium persulfate (APS).

[0017] Preferably, the volume ratio of pyrrole to the mass of the initiator in step (1) is (1-5) μL: (10-30) mg.

[0018] Preferably, the temperature of the polymerization reaction in step (1) is -3 to 3 °C, and the time is 1 to 5 h.

[0019] Preferably, in the polymerization reaction system of step (1), the initial concentration of pyrrole is 0.5 to 2.5 μL / mL.

[0020] Preferably, step (1) is specifically: after mixing the pyrrole dispersion and the initiator solution, carry out a polymerization reaction at -3 to 3 °C to obtain polypyrrole.

[0021] More preferably, the concentration of the pyrrole dispersion is 1 to 5 μL / mL, more preferably 5 μL / mL; the concentration of the initiator solution is 0.01 to 0.03 g / mL, more preferably 0.03 g / mL; the volume ratio of the pyrrole solution to the initiator solution is 1:1.

[0022] Preferably, the mass ratio of the polypyrrole, sodium alginate and calcium lignosulfonate in step (2) is (1 to 6):(15 to 20):(5 to 8); more preferably (5 to 6):(15 to 20):(6 to 7.5).

[0023] Preferably, the temperature of the cross-linking reaction in step (2) is room temperature, and the time is 12 to 18 h.

[0024] Preferably, in the system after the polypyrrole and sodium alginate (SA) are uniformly mixed in water in step (2), the concentration of the polypyrrole is 1 to 6 mg / mL; more preferably 5 to 6 mg / mL.

[0025] Preferably, the concentration of the calcium lignosulfonate solution in step (2) is 50 to 80 mg / mL; more preferably 60 to 75 mg / mL.

[0026] Preferably, the method of directional freezing in step (2) is a liquid nitrogen-assisted directional freezing method, specifically, the cross-linking reaction product is placed on a copper plate immersed in liquid nitrogen for directional freezing.

[0027] Preferably, the temperature of freeze-drying in step (2) is -58 to -90 °C, the pressure is 1 to 10 Pa, and the time is 24 to 48 h. Most preferably, the freeze-drying time is 48 h.

[0028] Preferably, the concentration of the LiCl solution in step (3) is 5.0 to 15 wt.%; more preferably 8 to 12 wt.%.

[0029] Preferably, the drying temperature in step (3) is 90 to 105 °C, and the time is 5 to 8 h.

[0030] Preferably, the mass ratio of the gel precursor described in step (3) to the volume of the LiCl solution is 0.5 - 2 g: 100 mL.

[0031] The present invention also provides a preparation method of the above-mentioned photothermal-driven water-electricity co-production composite material, which includes the following steps:

[0032] (1) Drop the pyrrole dispersion into the initiator solution for polymerization reaction. After washing with water, suction filtration and drying, polypyrrole powder is obtained.

[0033] (2) Disperse the polypyrrole powder in water, add sodium alginate, heat and stir evenly, then add calcium lignosulfonate solution, carry out sufficient cross-linking reaction, directionally freeze, and freeze-dry to obtain a gel precursor.

[0034] (3) Immerse the gel precursor in the LiCl solution, load LiCl, and dry to obtain the photothermal-driven water-electricity co-production composite material.

[0035] The present invention also provides a photothermal-driven water-electricity co-production composite material prepared by the above preparation method.

[0036] The present invention also provides an application of the above-mentioned photothermal-driven water-electricity co-production composite material.

[0037] Preferably, the application of the photothermal-driven water-electricity co-production composite material in fresh water collection and photothermal power generation.

[0038] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0039] 1. The present invention proposes a water collection system in which calcium lignosulfonate cross-links sodium alginate to form a three-dimensional interpenetrating network porous structure for loading hygroscopic salts. There is no report on the application research of this system in atmospheric water collection.

[0040] 2. The photothermal-driven water-electricity co-production composite material provided by the present invention uses PPy as the photothermal material, combines the lateral honeycomb porous skeleton of the composite material to enhance the scattering and absorption of light, reduces the interfacial reflection loss, and significantly improves the photothermal conversion performance of the material. Tests show that the photothermal-driven water-electricity co-production composite material has a broad-spectrum light capture efficiency of more than 97% in the spectral range of 300 - 2500 nm, and the surface temperature of the material can quickly rise to 93.4 °C (1.0 sun) within 30 minutes; it absorbs moisture under the condition of 30% relative humidity, and 93% of the water of the material itself can be evaporated in 60 min.

[0041] 3. The present invention uses a directional freezing process to prepare a vertically arranged layered porous structure, which is beneficial to reducing the tortuosity coefficient of the pore channels, reducing the diffusion resistance, and realizing a faster adsorption rate. At 30% relative humidity, the adsorption rate reaches 0.0203 g·g -1·min -1 。

[0042] 4. The photothermal-driven water-electricity co-generation composite material provided by the present invention has a wide range of hygroscopicity, and the water absorption amount can reach 0.6299 - 5.7493 g·g at a relative humidity of 7 - 95% -1 。

[0043] 5. The photothermal-driven water-electricity co-generation composite material provided by the present invention can fully utilize the enthalpy while collecting water, achieving the effect of simultaneously capturing water and generating thermoelectricity. The maximum electrical output power densities measured during the water absorption and desorption processes are 0.612 W / m 2 and 3.742 W / m 2 。 Description of the Drawings

[0044] Figure 1 SEM images of the transverse and longitudinal sections of the material prepared in Comparative Example 2;

[0045] Figure 2 SEM images of the transverse and longitudinal sections of the photothermal composite hygroscopic material prepared in Example 1;

[0046] Figure 3 UV-Vis-NIR spectra of Example 1, SC aerogel, and sodium alginate aerogel;

[0047] Figure 4 Mechanical strength curves of Example 1, Comparative Example 2, Comparative Example 5, and sodium alginate aerogel;

[0048] Figure 5 Hygroscopicity test results of the photothermal composite hygroscopic materials with different thicknesses prepared in Example 1;

[0049] Figure 6 Saturated adsorption amounts of the photothermal composite materials prepared in Example 1 and Comparative Example 4 under constant temperature and humidity conditions;

[0050] Figure 7a Saturated adsorption amounts of the photothermal composite materials prepared in Example 1, Example 6, and Example 7;

[0051] Figure 7b Adsorption kinetic curves of the photothermal composite hygroscopic materials prepared in Example 1 and Example 6;

[0052] Figure 8a Hygroscopicity comparison of the photothermal composite material prepared in Example 1, Comparative Example 2, 10 wt.% lithium chloride solution, and sodium alginate aerogel under the same conditions (RH = 60% ± 1%, T = 30°C ± 0.1°C, 1 h);

[0053] Figure 8b The comparative diagram of the equilibrium adsorption capacity of Example 1, Example 4 and Example 5 under the same conditions (RH = 60% ± 1%, T = 30°C ± 0.1°C);

[0054] Figure 9 The adsorption kinetic curves of Example 1, Comparative Example 6 and Comparative Example 7 (RH = 60% ± 1%, T = 30°C ± 0.1°C, 5h);

[0055] Figure 10 The water absorption process of the photothermal composite material prepared in Example 1 under an optical microscope (RH = 34% ± 1%, T = 23°C ± 1°C);

[0056] Figure 11 The desorption kinetic curves of Example 1, Comparative Example 1, Comparative Example 3, Comparative Example 6 and Comparative Example 7 after 5h of moisture absorption (RH = 60% ± 1%, T = 30°C ± 0.1°C);

[0057] Figure 12 The adsorption - desorption kinetic curves of the photothermal composite moisture - absorbing material prepared in Example 1 under different humidity conditions;

[0058] Figure 13 The adsorption isotherms of the photothermal composite moisture - absorbing material prepared in Example 1 under different temperature conditions;

[0059] Figure 14a The surface temperature change diagram of the photothermal composite moisture - absorbing materials prepared in Example 1 and Comparative Example 3 under different light intensities;

[0060] Figure 14b The thermal imaging diagram of the surface temperature change of the photothermal composite moisture - absorbing material prepared in Example 1 before and after desorption under one light intensity and different relative humidity conditions;

[0061] Figure 14c The surface thermal imaging diagram of the photothermal composite moisture - absorbing materials prepared in Example 2 and Example 3 after 10 minutes of sunlight irradiation;

[0062] Figure 15 The test results of the cyclic durability of the photothermal composite moisture - absorbing material prepared in Example 1;

[0063] Figure 16 The water collection diagram of the sealing device prepared with a transparent acrylic board;

[0064] Figure 17 The water quality test result diagram of the water collected by the photothermal composite moisture - absorbing material prepared in Example 1;

[0065] Figure 18Water absorption and voltage test results of the photothermal composite hygroscopic material prepared in Example 1 during the moisture absorption (left) and desorption (right) processes under a relative humidity of 30%. Detailed implementation mode

[0066] The present invention will be further described in detail below in conjunction with examples and drawings, but the implementation mode of the present invention is not limited thereto.

[0067] In the examples of the present invention, those not specified in specific conditions are carried out according to conventional conditions or conditions recommended by the manufacturer. Raw materials, reagents, etc. that are not specified in the manufacturer are all conventional products that can be obtained through commercial purchase.

[0068] Example 1

[0069] (1) Add 3 g of ammonium persulfate (APS) to 100 mL of deionized water, and stir to dissolve the ammonium persulfate (APS); use a pipette with a measuring range of 100 - 1000 μL to take 500 μL of pyrrole (Py), add it to 100 mL of deionized water, and stir for several minutes to disperse it evenly; drop the prepared pyrrole dispersion into the ammonium persulfate solution, and perform magnetic stirring to make it react fully at 0 °C. After 3 h, wash and filter the obtained polypyrrole (PPy) with water, dry it in an oven at 60 °C for 24 h, and grind it to prepare polypyrrole powder.

[0070] (2) Add 0.5 g of polypyrrole powder to 90 mL of deionized water and stir to disperse it evenly, and place it in a water bath at 50 °C; then add 2 g of sodium alginate (SA) to the above solution, and continue to heat and stir until it is evenly mixed.

[0071] (3) Add 0.75 g of calcium lignosulfonate (CLS) to 10 mL of deionized water, stir it magnetically to dissolve it, slowly drop it into (2), stir for 30 - 60 min to make it evenly mixed, pour it into a mold, and let it stand for 12 h to fully crosslink.

[0072] (4) Using liquid nitrogen as a cold source, place the above hydrogel on a copper plate immersed in liquid nitrogen for directional freezing, and then place it in a freeze dryer at -58 °C and 4 Pa for freeze drying for 48 h.

[0073] (5) Immerse 1.0 g of the above material in 100 mL of a LiCl solution with a mass fraction of 10 wt.% for 5 h, and then put it into a forced air drying oven at 95 °C for drying for 5 h to obtain the composite hygroscopic material SP 0.5 @LiCl - 10%.

[0074] Example 2

[0075] (1) Add 3 g of ammonium persulfate (APS) to 100 mL of deionized water and stir to dissolve the ammonium persulfate (APS). Use a pipette with a measuring range of 100 - 1000 μL to take 500 μL of pyrrole (Py), add it to 100 mL of deionized water, and stir for several minutes to disperse it evenly. Drop the prepared pyrrole dispersion into the ammonium persulfate solution and perform magnetic stirring to allow it to react fully at 0 °C. After 3 h, wash and filter the polypyrrole (PPy) obtained from the reaction, dry it in an oven at 60 °C for 24 h, and grind it to prepare polypyrrole powder.

[0076] (2) Add 0.1 g of polypyrrole powder to 90 mL of deionized water and stir to disperse it evenly, then place it in a 50 °C water bath. Then add 2 g of sodium alginate (SA) to the above solution and continue heating and stirring until it is evenly mixed.

[0077] (3) Add 0.75 g of calcium lignosulfonate (CLS) to 10 mL of deionized water, dissolve it by magnetic stirring, slowly drop it into (2), stir for 30 - 60 min to mix evenly, pour it into a mold, and let it stand for 12 h to fully crosslink.

[0078] (4) Using liquid nitrogen as a cold source, place the above hydrogel on a copper plate immersed in liquid nitrogen for directional freezing, and then place it in a freeze dryer at -58 °C and 4 Pa for freeze drying for 48 h.

[0079] (5) Immerse 1.0 g of the above material in 100 mL of a 10 wt.% LiCl solution for 5 h, and then place it in a forced-air drying oven at 95 °C for drying for 5 h to obtain the composite hygroscopic material SP 0.1 @LiCl-10%.

[0080] Example 3

[0081] (1) Add 3 g of ammonium persulfate (APS) to 100 mL of deionized water and stir to dissolve the ammonium persulfate (APS). Use a pipette with a measuring range of 100 - 1000 μL to take 500 μL of pyrrole (Py), add it to 100 mL of deionized water, and stir for several minutes to disperse it evenly. Drop the prepared pyrrole dispersion into the ammonium persulfate solution and perform magnetic stirring to allow it to react fully at 0 °C. After 3 h, wash and filter the polypyrrole (PPy) obtained from the reaction, dry it in an oven at 60 °C for 24 h, and grind it to prepare polypyrrole powder.

[0082] (2) Add 0.3 g of polypyrrole powder to 90 mL of deionized water and stir to disperse it evenly, then place it in a 50 °C water bath. Then add 2 g of sodium alginate (SA) to the above solution and continue heating and stirring until it is evenly mixed.

[0083] (3) Add 0.75 g of calcium lignosulfonate (CLS) to 10 mL of deionized water, stir magnetically to dissolve it, slowly drop it into (2), stir for 30 - 60 min to make the mixture uniform, pour it into a mold, and let it stand for 12 h to fully crosslink.

[0084] (4) Using liquid nitrogen as a cold source, place the above hydrogel on a copper plate immersed in liquid nitrogen for directional freezing, and then place it in a freeze dryer at -58 °C and 4 Pa for freeze drying for 48 h.

[0085] (5) Immerse 1.0 g of the above material in 100 mL of a LiCl solution with a mass fraction of 10 wt.%, soak for 5 h, and then place it in a forced air drying oven at 95 °C for drying for 5 h to obtain the composite hygroscopic material SP 0.3 @LiCl - 10%.

[0086] Example 4

[0087] (1) Add 3 g of ammonium persulfate (APS) to 100 mL of deionized water, stir to dissolve the ammonium persulfate (APS); use a pipette with a measuring range of 100 - 1000 μL to take 500 μL of pyrrole (Py), add it to 100 mL of deionized water, and stir for several minutes to disperse it evenly; drop the prepared pyrrole dispersion into the ammonium persulfate solution, stir magnetically, and let it react fully at 0 °C. After 3 h, wash the obtained polypyrrole (PPy) with water, filter it by suction, dry it in an oven at 60 °C for 24 h, and grind it to prepare polypyrrole powder.

[0088] (2) Add 0.5 g of polypyrrole powder to 90 mL of deionized water, stir to disperse it evenly, and place it in a water bath at 50 °C; then add 2 g of sodium alginate (SA) to the above solution, and continue to heat and stir until it is mixed evenly.

[0089] (3) Add 0.80 g of calcium lignosulfonate (CLS) to 10 mL of deionized water, stir magnetically to dissolve it, slowly drop it into (2), stir for 30 - 60 min to make the mixture uniform, pour it into a mold, and let it stand for 12 h to fully crosslink.

[0090] (4) Using liquid nitrogen as a cold source, place the above hydrogel on a copper plate immersed in liquid nitrogen for directional freezing, and then place it in a freeze dryer at -58 °C and 4 Pa for freeze drying for 48 h.

[0091] (5) Immerse 1.0 g of the above material in 100 mL of a LiCl solution with a mass fraction of 10 wt.%, soak for 5 h, and then place it in a forced air drying oven at 95 °C for drying for 5 h to obtain the composite hygroscopic material CAC 0.8 。

[0092] Example 5

[0093] (1) Add 3 g of ammonium persulfate (APS) to 100 mL of deionized water and stir to dissolve the ammonium persulfate (APS). Use a pipette with a volume range of 100 - 1000 μL to take 500 μL of pyrrole (Py), add it to 100 mL of deionized water, and stir for several minutes to disperse it evenly. Drop the prepared pyrrole dispersion into the ammonium persulfate solution and perform magnetic stirring to allow it to react fully at 0 °C. After 3 h, wash and filter the polypyrrole (PPy) obtained from the reaction, dry it in an oven at 60 °C for 24 h, and grind it to prepare polypyrrole powder.

[0094] (2) Add 0.5 g of polypyrrole powder to 90 mL of deionized water and stir to disperse it evenly, and place it in a 50 °C water bath. Then add 2 g of sodium alginate (SA) to the above solution and continue heating and stirring until it is evenly mixed.

[0095] (3) Add 0.50 g of calcium lignosulfonate (CLS) to 10 mL of deionized water, stir magnetically to dissolve it, slowly drip it into (2), stir for 30 - 60 min to mix evenly, pour it into a mold, and let it stand for 12 h to allow full cross-linking.

[0096] (4) Using liquid nitrogen as a cold source, place the above hydrogel on a copper plate immersed in liquid nitrogen for directional freezing, and then place it in a freeze dryer at -58 °C and 4 Pa for freeze drying for 48 h.

[0097] (5) Immerse 1.0 g of the above material in 100 mL of a LiCl solution with a mass fraction of 10 wt.% for 5 h, and then place it in a forced-air drying oven at 95 °C for drying for 5 h to obtain the composite moisture-absorbing material CAC 0.5 .

[0098] Example 6

[0099] (1) Add 3 g of ammonium persulfate (APS) to 100 mL of deionized water and stir to dissolve the ammonium persulfate (APS). Use a pipette with a volume range of 100 - 1000 μL to take 500 μL of pyrrole (Py), add it to 100 mL of deionized water, and stir for several minutes to disperse it evenly. Drop the prepared pyrrole dispersion into the ammonium persulfate solution and perform magnetic stirring to allow it to react fully at 0 °C. After 3 h, wash and filter the polypyrrole (PPy) obtained from the reaction, dry it in an oven at 60 °C for 24 h, and grind it to prepare polypyrrole powder.

[0100] (2) Add 0.5 g of polypyrrole powder to 90 mL of deionized water and stir to disperse it evenly, and place it in a 50 °C water bath. Then add 2 g of sodium alginate (SA) to the above solution and continue heating and stirring until it is evenly mixed.

[0101] (3) Add 0.75 g of calcium lignosulfonate (CLS) to 10 mL of deionized water, stir magnetically to dissolve it, slowly drop it into (2), stir for 30 - 60 min to make the mixture uniform, pour it into a mold, and let it stand for 12 h to fully crosslink.

[0102] (4) Using liquid nitrogen as a cold source, place the above hydrogel on a copper plate immersed in liquid nitrogen for directional freezing, and then place it in a freeze dryer at -58 °C and 4 Pa for freeze drying for 48 h.

[0103] (5) Immerse 1.0 g of the above material in 100 mL of a 5 wt.% LiCl solution for 5 h, and then place it in a forced air drying oven at 95 °C for drying for 5 h to obtain the composite hygroscopic material SP 0.5 @LiCl - 5%.

[0104] Example 7

[0105] (1) Add 3 g of ammonium persulfate (APS) to 100 mL of deionized water, stir to dissolve the ammonium persulfate (APS); use a pipette with a range of 100 - 1000 μL to take 500 μL of pyrrole (Py), add it to 100 mL of deionized water, and stir for several minutes to disperse it evenly; drop the prepared pyrrole dispersion into the ammonium persulfate solution, and stir magnetically to make it react fully at 0 °C. After 3 h, wash the obtained polypyrrole (PPy) with water, filter it by suction, dry it in an oven at 60 °C for 24 h, and grind it to prepare polypyrrole powder.

[0106] (2) Add 0.5 g of polypyrrole powder to 90 mL of deionized water, stir to disperse it evenly, and place it in a 50 °C water bath; then add 2 g of sodium alginate (SA) to the above solution, and continue to heat and stir until the mixture is uniform.

[0107] (3) Add 0.75 g of calcium lignosulfonate (CLS) to 10 mL of deionized water, stir magnetically to dissolve it, slowly drop it into (2), stir for 30 - 60 min to make the mixture uniform, pour it into a mold, and let it stand for 12 h to fully crosslink.

[0108] (4) Using liquid nitrogen as a cold source, place the above hydrogel on a copper plate immersed in liquid nitrogen for directional freezing, and then place it in a freeze dryer at -58 °C and 4 Pa for freeze drying for 48 h.

[0109] (5) Immerse 1.0 g of the above material in 100 mL of a 15 wt.% LiCl solution for 5 h, and then place it in a forced air drying oven at 95 °C for drying for 5 h to obtain the composite hygroscopic material SP 0.5 @LiCl - 15%.

[0110] Comparative Example 1

[0111] (1) Add 3 g of ammonium persulfate (APS) to 100 mL of deionized water, and stir to dissolve the ammonium persulfate (APS). Use a pipette with a measuring range of 100 - 1000 μL to take 500 μL of pyrrole (Py), add it to 100 mL of deionized water, and stir for several minutes to disperse it evenly. Drop the prepared pyrrole dispersion into the ammonium persulfate solution, and perform magnetic stirring to allow it to react fully at 0 °C. After 3 h, wash and filter the obtained polypyrrole (PPy) with water, dry it in an oven at 60 °C for 24 h, and grind it to prepare polypyrrole powder.

[0112] (2) Add 2 g of sodium alginate to 90 mL of deionized water, place it in a water bath at 50 °C, and stir well to dissolve it until it is evenly mixed.

[0113] (3) Add 0.75 g of calcium lignosulfonate (CLS) to 10 mL of deionized water, stir magnetically to dissolve it, slowly drop it into (2), stir for 30 - 60 min to mix evenly, pour it into a mold, and let it stand for 12 h to fully crosslink.

[0114] (4) Using liquid nitrogen as a cold source, place the above hydrogel on a copper plate immersed in liquid nitrogen for directional freezing, and then place it in a freeze dryer at -58 °C and 4 Pa for freeze drying for 48 h.

[0115] (5) Immerse 1.0 g of the above material in 100 mL of a LiCl solution with a mass fraction of 10 wt.% for 5 h, and then place it in a forced-air drying oven at 95 °C for drying for 5 h;

[0116] (6) Finally, add 0.05 g of polypyrrole powder to 10 mL of deionized water. After it is evenly dispersed, add 0.2 g of sodium alginate and stir well. Coat it on the hygroscopic material obtained in step (5), and place it in a forced-air drying oven at 90 °C for drying for 12 h to obtain the double-layer hygroscopic material SP 0.5 / LiCl - 10%.

[0117] Comparative Example 2 (Compared with Example 1, no hygroscopic inorganic salt is loaded)

[0118] (1) Add 3 g of ammonium persulfate (APS) to 100 mL of deionized water, and stir to dissolve the ammonium persulfate (APS). Use a pipette with a measuring range of 100 - 1000 μL to take 500 μL of pyrrole (Py), add it to 100 mL of deionized water, and stir for several minutes to disperse it evenly. Drop the prepared pyrrole dispersion into the ammonium persulfate solution, and perform magnetic stirring to allow it to react fully at 0 °C. After 3 h, wash and filter the obtained polypyrrole (PPy) with water, dry it in an oven at 60 °C for 24 h, and grind it to prepare polypyrrole powder.

[0119] (2) Add 0.5 g of polypyrrole powder to 90 mL of deionized water and stir to disperse it evenly, then place it in a water bath at 50 °C. Then add 2 g of sodium alginate (SA) to the above solution and continue heating and stirring until evenly mixed.

[0120] (3) Add 0.75 g of calcium lignosulfonate (CLS) to 10 mL of deionized water, dissolve it by magnetic stirring, slowly drop it into (2), stir for 30 - 60 min to make it evenly mixed, pour it into a mold, and let it stand for 12 h to fully crosslink.

[0121] (4) Using liquid nitrogen as a cold source, place the above hydrogel on a copper plate immersed in liquid nitrogen for directional freezing, and then place it in a freeze dryer at -58 °C and 4 Pa for freeze drying for 48 h to obtain sample SP 0.5 .

[0122] Comparative Example 3 (compared with Example 1, polypyrrole was not added)

[0123] (1) Add 2 g of sodium alginate to 90 mL of deionized water, place it in a water bath at 50 °C, and stir thoroughly to dissolve it until evenly mixed.

[0124] (2) Add 0.75 g of calcium lignosulfonate (CLS) to 10 mL of deionized water, dissolve it by magnetic stirring, slowly drop it into (1), stir for 30 - 60 min to make it evenly mixed, pour it into a mold, and let it stand for 12 h to fully crosslink.

[0125] (3) Using liquid nitrogen as a cold source, place the above hydrogel on a copper plate immersed in liquid nitrogen for directional freezing, and then place it in a freeze dryer at -58 °C and 4 Pa for freeze drying for 48 h.

[0126] (4) Immerse 1.0 g of the above material in 100 mL of a 10 wt.% LiCl solution for 5 h, and then place it in a blast drying oven at 95 °C for drying for 5 h to obtain the hygroscopic material S@LiCl - 10%.

[0127] Comparative Example 4 (compared with Example 1, the type of hygroscopic inorganic salt is different)

[0128] (1) Add 3 g of ammonium persulfate (APS) to 100 mL of deionized water and stir to dissolve the ammonium persulfate (APS). Use a pipette with a measuring range of 100 - 1000 μL to take 500 μL of pyrrole (Py), add it to 100 mL of deionized water, and stir for several minutes to disperse it evenly. Drop the prepared pyrrole dispersion into the ammonium persulfate solution and perform magnetic stirring to make it react fully at 0 °C. After 3 h, wash and filter the resulting polypyrrole (PPy) with water, dry it in an oven at 60 °C for 24 h, and grind it to prepare polypyrrole powder.

[0129] (2) Add 0.5 g of polypyrrole powder to 90 mL of deionized water, stir to make it evenly dispersed, and place it in a 50 °C water bath; then add 2 g of sodium alginate (SA) to the above solution, and continue heating and stirring until evenly mixed.

[0130] (3) Add 0.75 g of calcium lignosulfonate (CLS) to 10 mL of deionized water, dissolve it by magnetic stirring, slowly drop it into (2), stir for 30 - 60 min to make it evenly mixed, pour it into a mold, and let it stand for 12 h to fully crosslink.

[0131] (4) Using liquid nitrogen as a cold source, place the above hydrogel on a copper plate immersed in liquid nitrogen for directional freezing, and then place it in a freeze dryer at -58 °C and 4 Pa for freeze drying for 48 h.

[0132] (5) Immerse 1.0 g of the above material in 100 mL of a magnesium chloride (MgCl₂) solution or calcium chloride (CaCl₂) solution or zinc acetate ((CH₃COO)₂Zn) solution with a mass fraction of 10 wt. % for 5 h, and then place it in a forced-air drying oven at 95 °C for drying for 5 h to obtain a composite hygroscopic material.

[0133] Comparative Example 5 (compared with Example 1, replace calcium lignosulfonate with calcium chloride or aluminum chloride)

[0134] (1) Add 3 g of ammonium persulfate (APS) to 100 mL of deionized water, stir to dissolve ammonium persulfate (APS); use a pipette with a measuring range of 100 - 1000 μL to take 500 μL of pyrrole (Py), add it to 100 mL of deionized water, stir for several minutes to make it evenly dispersed; drop the prepared pyrrole dispersion into the ammonium persulfate solution, and perform magnetic stirring to make it react fully at 0 °C. After 3 h, wash and filter the obtained polypyrrole (PPy) with water, dry it in an oven at 60 °C for 24 h, and grind it to prepare polypyrrole powder.

[0135] (2) Add 0.5 g of polypyrrole powder to 90 mL of deionized water, stir to make it evenly dispersed, and place it in a 50 °C water bath; then add 2 g of sodium alginate (SA) to the above solution, and continue heating and stirring until evenly mixed.

[0136] (3) Slowly drop 10 mL of 0.024 moL / L calcium chloride (or 10 mL of 0.020 moL / L aluminum chloride) into (2), stir for 30 - 60 min to make it evenly mixed, pour it into a mold, and let it stand for 12 h to fully crosslink.

[0137] (4) Using liquid nitrogen as a cold source, place the above hydrogel on a copper plate immersed in liquid nitrogen for directional freezing, and then place it in a freeze dryer at -58 °C and 4 Pa for freeze drying for 48 h.

[0138] (5) Soak 1.0 g of the above material in 100 mL of a LiCl solution with a mass fraction of 10 wt.% for 5 h, and then place it in a forced-air drying oven at 95 °C for drying for 5 h to obtain the composite hygroscopic material CACa.

[0139] Comparative Example 6 (compared with Example 1, the addition timing of lithium chloride is different)

[0140] (1) Add 3 g of ammonium persulfate (APS) to 100 mL of deionized water, and stir to dissolve the ammonium persulfate (APS); use a pipette gun with a measuring range of 100 - 1000 μL to take 500 μL of pyrrole (Py), add it to 100 mL of deionized water, and stir for several minutes to disperse it evenly; drop the prepared pyrrole dispersion into the ammonium persulfate solution, and perform magnetic stirring to make it react fully at 0 °C. After 3 h, wash the obtained polypyrrole (PPy) with water, filter it by suction, dry it in an oven at 60 °C for 24 h, and grind it to prepare polypyrrole powder.

[0141] (2) Dissolve 10 g of LiCl in 90 mL of deionized water, then add 0.5 g of polypyrrole powder to it and stir to make it evenly dispersed, and place it in a 50 °C water bath; add 2 g of sodium alginate (SA) to the above solution, and continue to heat and stir until it is mixed evenly.

[0142] (3) Add 0.75 g of calcium lignosulfonate (CLS) to 10 mL of deionized water, stir magnetically to dissolve it, slowly drop it into (2), stir for 30 - 60 min to make it evenly mixed, pour it into a mold, and let it stand for 12 h to fully crosslink.

[0143] (4) Using liquid nitrogen as a cold source, place the above hydrogel on a copper plate immersed in liquid nitrogen for directional freezing, and then place it in a freeze dryer at -58 °C and 4 Pa for freeze drying for 48 h to prepare the sample LSP 0.5 。

[0144] Comparative Example 7 (compared with Example 1, polypyrrole is in-situ polymerized)

[0145] (1) Slowly add 2 g of sodium alginate (SA) to 90 mL of deionized water, and perform water bath at 50 °C, stir and dissolve until it is evenly mixed.

[0146] (2) Take 0.75 g of calcium lignosulfonate (CLS) and add it to 10 mL of deionized water, stir magnetically to dissolve it, slowly drop it into (1), stir for 30 - 60 min to make it evenly mixed, pour it into a mold, and let it stand for 12 h to fully crosslink.

[0147] (3) Using liquid nitrogen as a cold source, place the above hydrogel on a copper plate immersed in liquid nitrogen for directional freezing, and then place it in a freeze dryer at -58°C and 4 Pa for freeze drying for 48 h to obtain SC aerogel.

[0148] (4) Add 3 g of ammonium persulfate (APS) to 100 mL of deionized water and stir to dissolve the ammonium persulfate (APS); use a pipette with a measuring range of 100 - 1000 μL to take 500 μL of pyrrole (Py) and add it to 100 mL of deionized water, and stir for several minutes to disperse it evenly; soak 0.5 g of the SC aerogel prepared in step (3) in the ammonium persulfate solution, and drop the prepared pyrrole dispersion into the ammonium persulfate solution containing the SC aerogel, place it at 0°C for in-situ polymerization for 2 h, and then dry it in a forced air oven at 60°C for 5 h.

[0149] (5) Soak 1.0 g of the above material in 100 mL of a lithium chloride (LiCl) solution with a mass fraction of 10 wt.% for 5 h, and then place it in a forced air drying oven at 95°C for 5 h to obtain the composite hygroscopic material S@PPy / LiCl-10%.

[0150] Testing method:

[0151] 1. The compression modulus and maximum stress are measured by a Universal testing machine. The compression test is carried out at a rate of 100 mm·min -1 under the conditions of a temperature of 25°C and a relative humidity of 40% at a strain of 60%. The maximum stress is directly obtained from the stress-strain curve, and the Young's modulus of the photothermal composite hygroscopic material is calculated from the slope of the linear elastic region on the stress-strain curve. Each group of samples is tested 3 times and the average value is taken.

[0152] 2. Hygroscopic performance test: The relative humidity (RH) is used to conduct a static adsorption experiment under program control. During the test, the water absorption rate of the composite hygroscopic material is calculated using formula (1), where m i represents the mass after different hygroscopic times, and m0 represents the original mass of the composite material before hygroscopic.

[0153]

[0154] 3. Evaporation performance test: Use a xenon light source to simulate light, measure the light intensity with a light power density meter, record the change in the surface temperature of the sample with an infrared thermal imager, and calculate the water evaporation of the sample from the change in the reading of an analytical balance.

[0155] 4. Water quality detection: Detect the ion concentration of the collected water by inductively coupled plasma mass spectrometry (ICP-MS) and ion chromatography.

[0156] Figure 1SEM images of the transverse and longitudinal sections of the matrix material prepared in Comparative Example 2. In the figure, the matrix material obtained in (a) has a transverse honeycomb-like porous structure. With the help of multiple light scattering effects, the interfacial reflection loss is effectively reduced, thereby broadening the solar spectrum absorption range and significantly improving the photothermal conversion performance of the material. In the figure, the unique structure of vertical arrangement and ordered stratification formed by the directional freezing process in (b) serves as a water vapor transmission channel, accelerating the radial moisture convection, effectively reducing the diffusion resistance of water molecules, and promoting the adsorption process.

[0157] Figure 2 SEM images of the transverse and longitudinal cross-sections of the photothermal composite hygroscopic material prepared in Example 1. The photothermal composite hygroscopic material is prepared from a composite photothermal material and a hygroscopic salt, forming a nanocomposite material with a low degree of distortion. By reducing the effective diffusion layer thickness of the material to the micron scale, the desorption kinetics performance is further improved.

[0158] Figure 3 UV-Vis-NIR test charts of Example 1, SC aerogel, and sodium alginate aerogel. The test results show that: with the addition of calcium lignosulfonate, the absorption rate of the matrix material in the ultraviolet and visible light regions is significantly enhanced; further, when the photothermal material polypyrrole is introduced, the light absorption ability of the composite material in the entire spectral range is greatly improved, mainly due to the enhanced light scattering and absorption of the three-dimensional interconnected structure of the matrix material. In addition, the test of the composite material after moisture absorption shows that its light absorption rate can reach more than 97%, slightly higher than that of the photothermal composite material in the dry state.

[0159] Figure 4 Stress-strain curves of the composite materials prepared in Example 1, Comparative Example 2, and Comparative Example 5, and sodium alginate aerogel. Direct cross-linking with CaCl2 is prone to agglomeration, forming an uneven gel network, and the ionic bond interaction force is weak, resulting in a low compression modulus. Excessive moisture absorption in a high-humidity environment causes structural damage. In contrast, after adding calcium lignosulfonate, the chelation of Ca 2+ with sodium alginate and the rigid structure of the lignosulfonate itself increase the compression modulus of the material by 11.8 times. This stable structure helps the composite material maintain stable performance during the adsorption and desorption cycles, thus maximizing the water collection in the hollow structure.

[0160] Figure 5The adsorption amounts of the composite materials with different thicknesses prepared in Example 1 after adsorbing for 5 h under constant temperature and humidity conditions (RH = 90% ± 1%, T = 30°C ± 0.1°C). Under the conditions of thicknesses of 0.3 mm, 1.0 mm, 4.0 mm, and 8.0 mm, the moisture absorption rates are 5.55 g / g, 2.91 g / g, 2.19 g / g, and 1.88 g / g respectively. The results show that the thickness of the composite material has a significant impact on its moisture absorption rate, and among them, the photothermal composite material with a thickness of 300 μm exhibits the highest moisture absorption rate.

[0161] Figure 6 The saturated adsorption amounts of the materials prepared in Example 1 and Comparative Example 4 loaded with different inorganic moisture-absorbing salts (magnesium chloride, calcium chloride, zinc acetate, lithium chloride) under constant temperature and humidity conditions (RH = 90% ± 1%, T = 30°C ± 0.1°C). The results show that: SP 0.5 @The saturated adsorption amount of LiCl-10% loaded with lithium chloride is the largest, mainly because the lithium ion radius in the lithium chloride molecule is small, the adsorption of electrons is strong, and it is easy to adsorb O in water. Therefore, lithium ions have strong water absorption ability.

[0162] Figure 7 shows the saturated adsorption amounts of the composite materials prepared in Example 1, Example 6, and Example 7, as well as the adsorption kinetic curves of the composite moisture-absorbing materials prepared in Example 1 and Example 6 (RH = 90% ± 1%, T = 30°C ± 0.1°C). The results show that: The composite moisture-absorbing material prepared by impregnating with 5 wt.% lithium chloride has the highest adsorption capacity, but it can be clearly seen from the adsorption kinetics that the composite material impregnated with 10 wt.% lithium chloride has a faster adsorption rate. Thanks to the porous structure of the matrix and the moderate lithium chloride loading amount, the slow adsorption caused by deliquescence is avoided. Therefore, the composite moisture-absorbing material is prepared by impregnating with 10 wt.% lithium chloride.

[0163] Figure 8a The comparison of the moisture absorption performance of the composite material prepared in Example 1, Comparative Example 2, 10 wt.% lithium chloride solution, and sodium alginate aerogel under the same conditions (RH = 60% ± 1%, T = 30°C ± 0.1°C, 1 h). SP 0.5 @LiCl-10%, SP 0.5 、The adsorption rates of 10 wt.% LiCl solution and sodium alginate aerogel are: 1.98 g / g, 0.44 g / g, 1.38 g / g, and 0.25 g / g respectively. The moisture absorption results show that when lithium chloride is compounded with the matrix skeleton, its water absorption ability is significantly improved. This shows that the vertically arranged and layered pore structure formed by crosslinking calcium lignosulfonate and sodium alginate provides an effective pore channel for the loading of water, thereby improving the adsorption capacity. Figure 8bComparative diagram of equilibrium adsorption amounts of Example 1, Example 4, and Example 5 under the same conditions (RH = 60% ± 1%, T = 30°C ± 0.1°C). By changing the concentration of calcium lignosulfonate, the crosslinking network density is regulated. Figure 8b It can be clearly seen that the higher the crosslinking agent concentration, the denser the crosslinking network and the lower the equilibrium adsorption amount.

[0164] Figure 9 Adsorption curves of Example 1, Comparative Example 6, and Comparative Example 7 (RH = 60% ± 1%, T = 30°C ± 0.1°C) for 5 h. In Comparative Example 6, LiCl was introduced during the formation of the aerogel, which affected its microstructure and significantly reduced the adsorption rate. For Comparative Example 7, in-situ polymerization of PPy was used, and LiCl was loaded after drying. Due to the introduction of PPy, due to the physical blocking effect of the PPy segments on the pores, the density of effective adsorption sites in the pore structure of the material decreased, resulting in a decrease in the adsorption capacity.

[0165] Figure 10 Water absorption process of the composite material prepared in Example 1 under an optical microscope (RH = 34% ± 1%, T = 23°C ± 1°C). The results show that as adsorption proceeds, the surface of the composite material is gradually wetted by water, forming small water droplets. These water droplets are quickly adsorbed and spread, and finally form larger water stains spreading flat on the surface of the material.

[0166] Figure 11 Desorption curves of Example 1, Comparative Example 1, Comparative Example 3, Comparative Example 6, and Comparative Example 7 after moisture absorption at RH = 60% ± 1%, T = 30°C ± 0.1°C for 5 h. The experimental data show that compared with Comparative Example 3, Example 1 significantly improves the photothermal conversion efficiency of the material by loading polypyrrole (PPy), showing the most excellent desorption kinetic performance. For the double-layer coated composite material prepared in Comparative Example 1, due to the lack of doping of the photothermal agent in the water absorption layer, the desorption is slow during the whole evaporation process, and the equilibrium desorption amount decreases by about 17.87% compared with the single-layer structure. In Comparative Example 6, the one-pot synthesis method was used, and the strong ionization effect of LiCl destroyed the vertically oriented mesoporous structure of the material, resulting in blocked desorption paths. In Comparative Example 7, the in-situ polymerization method was used to load the hygroscopic salt on the surface of PPy. During multiple adsorption-desorption cycles, salting out occurred on the surface, increasing the mass transfer resistance and reducing the desorption rate, and shortening the cycle service life of the sample.

[0167] Figure 12 Adsorption-desorption kinetic curves of the composite material prepared in Example 1 at 30°C under conditions of relative humidity of 30%, 60%, and 90%. The moisture absorption results show that faster adsorption kinetics and higher adsorption rates are exhibited under higher relative humidity conditions. When the relative humidity gradually increases from 30% to 90%, the adsorption rate within 5 h changes from 0.0203 g·g -1 ·min-1 Increased to 0.0695 g·g -1 ·min -1 ; On the contrary, at lower relative humidity, the composite material shows a higher surface temperature during the desorption process. In Figure 14b , when desorbing for 1 h at a relative humidity of 30%, the surface temperature of the composite material reaches 92.8 °C, and the desorption kinetics is significantly accelerated, releasing 93% of its own weight of water within 1 h. This is mainly due to the interaction between the hydrophilic matrix and the adsorbed water, which makes more water molecules exist in the form of free water and intermediate water, reducing the desorption heat and facilitating the rapid desorption of water.

[0168] Figure 13 Adsorption isotherms of the photothermal composite material prepared in Example 1 at different temperatures. The results show that the composite material prepared in Example 1 exhibits excellent moisture absorption capacity at 20 °C and 30 °C. As the temperature rises to 45 °C, the adsorption capacity decreases under conditions of relatively high relative humidity.

[0169] Figure 14a Figure showing the change in surface temperature of the photothermal composite materials prepared in Example 1 and Comparative Example 3 under different light intensities, and Figure 14b shows the surface temperature when evaporation is stable under different relative humidities (30%, 60%, 90%) for Example 1. Figure 14c Surface temperature of Example 2 (left) and Example 3 (right) irradiated with 1.0 sun for 10 min. After irradiating for 1 h under different light intensities (0.5 sun, 1.0 sun, 1.5 sun, 2.0 sun) for Example 1, the corresponding surface temperatures are 63.9 °C, 93.4 °C, 116.7 °C, and 142 °C respectively.

[0170] Figure 15 Twenty-one adsorption-desorption cycle experiments were carried out on the composite material prepared in Example 1 under the conditions of a relative humidity of 60% and adsorption for 80 min. The experimental results show that: after 21 adsorption-desorption cycles, the material still has high cycle stability, the water absorption rate remains at 96.53%, and the water absorption capacity does not show an obvious decline, indicating good recyclability.

[0171] Figure 16 Figure showing water collection of the sealing device prepared with a transparent acrylic plate. The photothermal composite moisture-absorbing material prepared in Example 1 was exposed to the indoor environment for moisture absorption for 12 h (the moisture absorption time was from 22:00 at night to 10:00 the next day, the ambient temperature was 14 °C to 18 °C, and the relative humidity was 72% to 93%). Subsequently, evaporation water collection tests were carried out on the above-mentioned moisture-absorbed photothermal composite moisture-absorbing material under a certain light intensity.

[0172] Figure 17 For Figure 16The water quality test results of the water collected by the photothermal composite hygroscopic material prepared in Example 1. The results show that the concentration of Li in the collected water is 0.18 mg / L, and the concentration of Cl is 0.5 mg / L. Comparing with the WHO drinking water standard, these ion concentrations are far lower than the limits specified by WHO, indicating that the water collected by this composite material meets the drinking water standard. + The concentration of Li is 0.18 mg / L, and the concentration of Cl - is 0.5 mg / L. Comparing with the WHO drinking water standard, these ion concentrations are far lower than the limits specified by WHO, indicating that the water collected by this composite material meets the drinking water standard.

[0173] Figure 18 SP 0.5 @LiCl-10% hygroscopic material prepared in Example 1 under the condition of relative humidity 30% (A = 7.065 cm 2 ). During the moisture absorption and desorption processes, the water absorption amount and the change of output voltage of the composite material are shown. In the experiment, the tap water circulated water is used as the cold end of the thermoelectric module, and the temperature is maintained at about 15°C ± 1°C. As the moisture absorption proceeds, a temperature difference is generated between the composite material and the cold end, and the open circuit voltage (Voc) reaches 49.54 mV. As the moisture absorption proceeds, the temperature difference gradually decreases, resulting in the gradual decrease of the temperature of the absorption layer and the weakening of the electrical signal to 21.14 mV. In the desorption stage, SP 0.5 @LiCl-10% rapidly heats up under a light condition, and the surface temperature rises to about 92.8°C within 1 h. Within the first 10 minutes of desorption, the open circuit voltage (Voc) rapidly rises to 157.32 mV and then stabilizes. The maximum output power densities measured during the absorption and desorption processes are 0.612 W / m 2 and 3.742 W / m 2 .

[0174] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A preparation method of a photothermal-driven water-electricity co-production composite material, characterized in that, It includes the following steps: (1) Pyrrole is polymerized under the initiation of an initiator to obtain polypyrrole; (2) After polypyrrole and sodium alginate are mixed evenly in water, a calcium lignosulfonate solution is added for sufficient cross-linking reaction, followed by directional freezing and freeze-drying to obtain a gel precursor; (3) The gel precursor is soaked in a LiCl solution to load LiCl and then dried to obtain a photothermal-driven water-electricity co-generation composite material.

2. The preparation method according to claim 1, wherein In step (2), the mass ratio of polypyrrole, sodium alginate, and calcium lignosulfonate is (1-6):(15-20):(5-8); And / or, the temperature of the cross-linking reaction in step (2) is room temperature, and the time is 12-18 h.

3. The preparation method according to claim 1, wherein The concentration of the calcium lignosulfonate solution in step (2) is 50-80 mg / mL or 60-75 mg / mL; And / or, in the system after polypyrrole and sodium alginate (SA) are mixed evenly in water in step (2), the concentration of polypyrrole is 1-6 mg / mL or 5-6 mg / mL.

4. The preparation method according to claim 1, wherein The concentration of the LiCl solution in step (3) is 5.0-15 wt.% or 8-12 wt.%; And / or, the mass ratio of the gel precursor to the volume of the LiCl solution in step (3) is 0.5-2 g:100 mL.

5. The preparation method according to claim 1, characterized in that, The initiator in step (1) is ammonium persulfate; And / or, the volume ratio of pyrrole to the mass of the initiator in step (1) is (1-5) μL:(10-30) mg; And / or, the temperature of the polymerization reaction in step (1) is -3-3 °C, and the time is 1-5 h; And / or, in the polymerization reaction system in step (1), the initial concentration of pyrrole is 0.5-2.5 μL / mL.

6. The preparation method according to claim 1, wherein, Step (1) is specifically: After mixing a pyrrole dispersion and an initiator solution, the polymerization reaction is carried out at -3-3 °C to obtain polypyrrole; And / or, the concentration of the pyrrole dispersion is 1-5 μL / mL; the concentration of the initiator solution is 0.01-0.03 g / mL; the volume ratio of the pyrrole solution to the initiator solution is 1:

1.

7. According to the preparation method described in claim 1, characterized in that, The method of directional freezing in step (2) is liquid nitrogen-assisted directional freezing method; And / or, the temperature of freeze-drying in step (2) is -58--90 °C, the pressure is 1-10 Pa, and the time is 24-48 h.

8. According to the preparation method described in claim 1, wherein It includes the following steps: (1) Drop a pyrrole dispersion into an initiator solution for polymerization reaction. After washing, suction filtration, and drying, polypyrrole powder is obtained; (2) Disperse the polypyrrole powder in water, add sodium alginate, heat and stir evenly, then add a calcium lignosulfonate solution for sufficient cross-linking reaction, followed by directional freezing and freeze-drying to obtain a gel precursor; (3) Soak the gel precursor in a LiCl solution to load LiCl and then dry to obtain a photothermal-driven water-electricity co-generation composite material.

9. A photothermal-driven water-electricity co-generation composite material prepared by the preparation method according to any one of claims 1-8.

10. The application of the photothermal-driven water-electricity co-generation composite material according to claim 9.

Images