High-moisture-retention composite material for extracting water from air and co-producing hydrogen and water through photocatalysis as well as preparation method and application of high-moisture-retention composite material

Abstract

The invention belongs to the technical field of photocatalytic materials, hydrogel composite materials and renewable energy sources, and discloses a high-moisture-retention air water taking-photocatalytic hydrogen water co-production composite material and a preparation method and application thereof.The high-moisture-retention air water taking-photocatalytic hydrogen water co-production composite material is obtained by conducting light polymerization and drying on a mixture containing Ag / TiO2, acrylic acid-2-hydroxyethyl ester and a photoinitiator; a photocatalytic layer gel base material is obtained; the preparation method comprises the following steps: mixing a mixture containing acrylamide, water and a photoinitiator with a mixture containing 2-hydroxyethyl acrylate and a photoinitiator, adding a LiCl saturated solution, uniformly mixing, carrying out photopolymerization, and drying to obtain a moisture absorption layer gel base material; the photocatalytic layer gel base material is placed on the moisture absorption layer gel base material, and the high-moisture-retention air water taking-photocatalytic hydrogen water co-production composite material is formed. Through collaborative design of the bottom moisture absorption layer gel base material and the upper photocatalytic layer gel base material, efficient capture of atmospheric moisture and solar-driven hydrogen-fresh water co-production are realized.

Description

Technical Field

[0001] The present invention belongs to the technical fields of photocatalytic materials, hydrogel composites and renewable energy, and particularly relates to a high-moisture-retention air water harvesting-photocatalytic hydrogen and water co-production composite material, a preparation method thereof and an application thereof. Background Art

[0002] With the intensification of the global energy crisis and freshwater shortage, the development of low-carbon and sustainable hydrogen production technologies has become a research hotspot. Photocatalytic hydrogen evolution (PHE) technology, which directly uses solar energy to drive water decomposition, has attracted much attention due to its potential. However, traditional PHE systems rely heavily on liquid water (such as pure water, seawater or wastewater) as reactants, which limits their practical applications due to the geographical distribution of water sources, especially in arid regions. In recent years, hydrogen production technologies based on air water harvesting (AWH) have provided new insights for scenarios without liquid water supply. However, there are still two major challenges: (1) the slow kinetics of hygroscopic materials leads to insufficient water vapor supply efficiency; (2) the waste of unreacted water vapor during the photothermal-photocatalytic coupling process further exacerbates freshwater consumption in water-scarce areas.

[0003] Current research mainly focuses on using hygroscopic materials (such as metal-organic frameworks (MOFs), base composites) to capture atmospheric water vapor to drive photocatalytic hydrogen evolution reactions. Yan et al. demonstrated a MOF-based AWH-PHE system that can continuously produce hydrogen at 30% relative humidity (RH) (Nano Lett. 2025, 25, 71-76). However, the hygroscopic kinetics of this system are still limited by the slow adsorption-desorption rate of water molecules on the material surface, resulting in low hydrogen production efficiency. In addition, existing systems usually ignore the key issue of recycling unreacted water vapor during the photothermal driving process, leading to a large amount of water resource loss (Nano Energy, 2024, 128, 109879). More critically, most photocatalytic configurations rely heavily on sacrificial agents (such as methanol, ethanol) to suppress oxidation side reactions, which not only increases the operating cost but also fundamentally undermines the sustainability of the system. Summary of the Invention

[0004] To overcome the problems in the prior art that the air water harvesting-coupled photocatalytic hydrogen production system lacks water due to insufficient moisture absorption and water retention ability at the reaction interface, and the hydrogen production efficiency is low due to limited mass transfer of the carrier, the object of the present invention is to provide a high-moisture-retention air water harvesting-photocatalytic hydrogen and water co-production composite material, a preparation method thereof and an application thereof, to achieve air water harvesting-photocatalytic hydrogen and water co-production, while ensuring the mechanical properties of the material and broadening the application range of the hydrogel composite material.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A preparation method of a high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material, comprising the following steps:

[0007] Subject a mixture containing Ag / TiO2, 2-hydroxyethyl acrylate and a photoinitiator to light polymerization and drying to obtain a photocatalytic layer gel substrate;

[0008] Mix a mixture containing acrylamide, water and a photoinitiator with a mixture containing 2-hydroxyethyl acrylate and a photoinitiator to obtain a pre-gel solution;

[0009] Add a saturated LiCl solution to the pre-gel solution, mix evenly, then carry out light polymerization and drying to obtain a moisture absorption layer gel substrate;

[0010] Place the photocatalytic layer gel substrate on the moisture absorption layer gel substrate to form a high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material.

[0011] Further, the photoinitiator is diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide.

[0012] Further, in the mixture containing acrylamide, water and a photoinitiator, the mass ratio of acrylamide to the photoinitiator is 100:0.1-0.2.

[0013] Further, in the mixture containing Ag / TiO2, 2-hydroxyethyl acrylate and a photoinitiator, the mass ratio of 2-hydroxyethyl acrylate to the photoinitiator is 100:0.1-0.2.

[0014] Further, the volume ratio of 2-hydroxyethyl acrylate to the saturated LiCl solution is 0.01-0.2:1.

[0015] Further, the volume ratio of the photocatalytic layer gel substrate to the moisture absorption layer gel substrate is 0.2-1:1.

[0016] Further, the mass ratio of Ag / TiO2 to 2-hydroxyethyl acrylate is 0.4-2:100.

[0017] Further, in the mixture containing 2-hydroxyethyl acrylate and a photoinitiator, the mass ratio of the photoinitiator to 2-hydroxyethyl acrylate is 0.1-0.2:100; the volume ratio of the mixture containing acrylamide, water and a photoinitiator to the mixture containing 2-hydroxyethyl acrylate and a photoinitiator is 2:1.

[0018] A high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material.

[0019] Application of a high-moisture-retention air water harvesting-photocatalytic hydrogen water co-production composite material in air water harvesting-photocatalytic hydrogen production.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] Through a "root-leaf" hierarchical bionic design, the gel substrate of the moisture absorption layer (P(AcH)-L) simulates the efficient water absorption and transport functions of plant roots, rapidly captures atmospheric moisture through a three-dimensional through-hole porous network and stores it; the gel substrate of the photocatalytic layer (Ag-TiO2 / P(HEA)) simulates the photosynthesis mechanism of leaves. By regulating the contents of the photocatalyst Ag-TiO2, 2-hydroxyethyl acrylate, photoinitiator, and the UV irradiation time, the gel substrate of the photocatalytic layer is successfully prepared, and solar energy is used to drive the decomposition of water molecules to produce hydrogen and simultaneously release fresh water. Through the hydrogen bond interaction between 2-hydroxyethyl acrylate and the TiO2 surface, chemical anchoring sites are constructed to solve the problem of catalyst shedding caused by traditional physical loading. The gel substrate of the moisture absorption layer regulates the mass ratio of 2-hydroxyethyl acrylate and acrylamide, and the mass ratio of the photoinitiator to 2-hydroxyethyl acrylate and acrylamide. The moisture absorption salt LiCl is pre-mixed and embedded into the main chain of the moisture absorption layer gel polymer to form an ion-dipole interaction, reducing the salt loss rate and ensuring long-term cycle stability. By regulating the mass ratio of the photocatalytic layer and the hydrogel layer, high-efficiency moisture absorption-hydrogen water co-production efficiency is achieved. In the present invention, plasma Ag-modified TiO2 is introduced into the gel substrate of the photocatalytic layer, broadening the light absorption to the near-infrared band, and using the photothermal effect to accelerate the desorption of water in the moisture absorption layer, enabling a closed-loop cycle of moisture absorption at night and hydrogen production-fresh water release during the day. By ultraviolet light curing, energy consumption is reduced and large-scale production can be realized, adapting to the distributed water-hydrogen co-production requirements in multiple scenarios such as deserts, islands, and plateaus, providing core technical support for off-grid water supply systems driven by renewable energy. Description of the Drawings

[0022] Figure 1 Schematic diagrams of the prepared photocatalytic layer Ag-TiO2 / P(HEA) and moisture absorption layer P(AcH)-L hydrogel materials; among them, (a) is the photocatalytic layer Ag-TiO2 / P(HEA), and (b) is the moisture absorption layer P(AcH)-L;

[0023] Figure 2 SEM of samples P(AcH)-L and Ag-TiO2; among them, (a) is P(AcH)-L, and (b) is Ag-TiO2;

[0024] Figure 3 XRD patterns of the photocatalytic layer Ag-TiO2 / P(HEA) and moisture absorption layer P(AcH)-L hydrogel materials;

[0025] Figure 4FT-IR spectra of Ag-TiO2 / P(HEA) and P(AcH)-L;

[0026] Figure 5 Moisture absorption performance test diagrams of P(AcH)-L composite moisture-absorbing materials at 30% RH, 60% RH, 70% RH, and 90% RH;

[0027] Figure 6 Photocatalytic hydrogen production performance diagrams of Ag-TiO2 / P(HEA) and P(AcH)-L at different humidities;

[0028] Figure 7 Comparison diagrams of photocatalytic hydrogen production performance of photocatalytic layer Ag-TiO2 / P(HEA), moisture-absorbing layer P(AcH)-L, photocatalytic + moisture-absorbing layer immersed in liquid water, and photocatalytic + moisture-absorbing layer after moisture absorption;

[0029] Figure 8 Diagrams of light irradiation water vapor desorption rate and condensed water collection content of Ag-TiO2 / P(HEA) and P(AcH)-L at different humidities. Detailed implementation manners

[0030] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive.

[0031] The present invention provides a high-moisture-retention air water extraction-photocatalytic hydrogen water co-production composite material, which can capture moisture from the air and realize hydrogen production, and does not require additional sacrificial agents. At the same time, it promotes water evaporation through the photothermal effect and collects excess liquid water, which can alleviate the global shortage of fresh water resources and provide a new feasible way to solve the global energy crisis.

[0032] A preparation method of a high-moisture-retention air water extraction-photocatalytic hydrogen water co-production composite material in the present invention includes the following steps:

[0033] 1) Preparation of photocatalyst: Titanium dioxide loaded with Ag (Ag / TiO2) was synthesized by photodeposition. The specific process was as follows: 0.2 g of TiO2 was dispersed in an aqueous solution containing 50 mL of water and 10 mL of methanol. Then, 200 μL of an aqueous AgNO3 solution (92.6 mmol / L) was added, and the mixture was purged with high-purity N2 gas for 15 minutes to remove dissolved oxygen. Subsequently, the mixture was transferred to a sealed transparent container and irradiated under a 300 W xenon lamp for 5 minutes, followed by washing with alcohol and water, and vacuum drying at 70 °C for 12 h to collect the powder sample, obtaining the photocatalyst, denoted as Ag / TiO2.

[0034] 2) Preparation of photocatalytic layer gel substrate:

[0035] Ag / TiO2 was dispersed in a solution of 2-hydroxyethyl acrylate (HEA) to obtain a pre-gel solution. A diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide photoinitiator was added, and the mixture was ultrasonically mixed evenly and placed under a xenon lamp for photo-polymerization. After the sample was completely polymerized, it was transferred to an oven and completely dried to obtain TiO2-P(HEA).

[0036] Preferably, the ultrasonic time was 5 - 10 min;

[0037] The irradiation time was 1 - 5 min, preferably 1 min, 2 min or 5 min, etc.;

[0038] In step 2), the mass ratio of the photocatalyst to the HEA monomer was 0.4 - 2:100;

[0039] The mass ratio of the photoinitiator to the HEA monomer was 0.1 - 0.2:100;

[0040] The drying temperature of the ordinary oven was 70 - 90 °C, and the drying time was 12 - 24 h.

[0041] 3) Preparation of moisture-absorbing layer gel substrate:

[0042] According to the mass ratio of acrylamide to the photoinitiator of 100:0.1 - 0.2, acrylamide was dissolved in water and ultrasonically dispersed evenly. The photoinitiator was added and ultrasonically mixed evenly. The ultrasonic time was 2 - 8 min, preferably 5 min, to obtain solution A.

[0043] Press again. Add 2-hydroxyethyl acrylate to the photoinitiator according to the mass ratio of 2-hydroxyethyl acrylate to the photoinitiator of 100:0.1 - 0.2, and mix evenly by ultrasonic treatment. The ultrasonic time is 2 - 8 min, preferably 5 min, to obtain Solution B. Mix the above two solutions according to the volume ratio of Solution A to Solution B of 2:1 to obtain a pre-gel solution. Then, add a saturated LiCl solution to the pre-gel solution, mix it evenly by a rotary shaker, place it under a xenon lamp for photo-polymerization. After the sample is completely polymerized, transfer it to an oven and dry it completely to obtain a gel substrate containing PAAm, HEA, and LiCl.

[0044] Among them, the photo-irradiation time is 1 - 10 min, preferably 2 min, 4 min, 6 min, or 8 min, etc.

[0045] The drying temperature of the ordinary oven is 70 - 90 °C, and the drying time is 12 - 48 h.

[0046] The volume ratio of 2-hydroxyethyl acrylate to the saturated LiCl solution is 0.01 - 0.2:1.

[0047] 4) Place the photocatalytic layer gel substrate on the moisture absorption layer gel substrate. The moisture absorption layer gel substrate is located at the bottom layer, and the photocatalytic layer gel substrate is located at the top layer. The two are in contact to form a high-moisture air water intake-photocatalytic hydrogen water co-production composite material.

[0048] In step 2), the volume ratio of the photocatalytic layer gel substrate to the moisture absorption layer gel substrate in step 3) is 0.2 - 1:1.

[0049] Specifically, acrylamide (AAm) monomer and 2-hydroxyethyl acrylate (HEA) monomer are commercially available raw materials.

[0050] The high-moisture air water intake-photocatalytic hydrogen water co-production composite material prepared by the present invention can be used in air water intake-photocatalytic hydrogen production.

[0051] The following are specific examples.

[0052] Example 1

[0053] This example provides a preparation method of a high-moisture air water intake-photocatalytic hydrogen water co-production composite material. The steps are as follows:

[0054] 1) Disperse 5 mg of Ag / TiO₂ in 1 mL of 2 - hydroxyethyl acrylate (HEA) solution to obtain a pre - gel solution. Add 1.5 mg of diphenyl - (2,4,6 - trimethylbenzoyl) phosphine oxide photo - initiator to the pre - gel solution, ultrasonicate for 5 min, mix evenly, place it under a xenon lamp for photo - polymerization for 1 min. After the sample is completely polymerized, transfer it to an oven at 80 °C to dry it completely, obtaining a photocatalytic layer gel substrate, namely 5 - Ag / TiO₂ - P(HEA).

[0055] 2) Dissolve 0.5 g of acrylamide in 0.5 mL of water, ultrasonically disperse it evenly, add 0.75 mg of photo - initiator and ultrasonically mix evenly to obtain solution A. Then take 0.5 mL of 2 - hydroxyethyl acrylate, add 0.75 mg of photo - initiator, ultrasonicate for 5 min, mix evenly to obtain solution B. Take 240 μL of solution A and 120 μL of solution B and mix them to obtain a pre - gel solution. Then add 2 mL of saturated LiCl solution to the pre - gel solution, mix it evenly by a rotary shaker, place it under a xenon lamp for photo - polymerization for 4 min. After the sample is completely polymerized, transfer it to an oven at 80 °C and dry it for 12 h, obtaining a high - moisture - retaining air - water - harvesting and photocatalytic hydrogen - rich water co - production composite material, namely a composite material containing P(AcH) - L gel substrate.

[0056] 3) According to the volume ratio of the photocatalytic layer gel substrate to the moisture - absorbing layer gel substrate of 0.5:1, place the photocatalytic layer gel substrate on the moisture - absorbing layer gel substrate. The moisture - absorbing layer gel substrate is located at the bottom layer and the photocatalytic layer gel substrate is located at the top layer. The two are in contact to form a high - moisture - retaining air - water - harvesting and photocatalytic hydrogen - rich water co - production composite material.

[0057] Example 2

[0058] This example provides a preparation method of a high - moisture - retaining air - water - harvesting and photocatalytic hydrogen - rich water co - production composite material, and the steps are as follows:

[0059] 1) Disperse 10 mg of Ag / TiO₂ in 1 mL of 2 - hydroxyethyl acrylate (HEA) solution to obtain a pre - gel solution. Add 1.5 mg of diphenyl - (2,4,6 - trimethylbenzoyl) phosphine oxide photo - initiator and ultrasonicate for 5 min, mix evenly, place it under a xenon lamp for photo - polymerization for 1 min. After the sample is completely polymerized, transfer it to an oven at 80 °C to dry it completely, obtaining a photocatalytic layer gel substrate, namely 10 - Ag / TiO₂ - P(HEA), named Ag / TiO₂ - P(HEA).

[0060] 2) Dissolve 0.5 g of acrylamide in 0.5 mL of water, ultrasonically disperse it evenly, add 0.75 mg of photoinitiator and ultrasonically mix it evenly to obtain Solution A. Then take 0.5 mL of 2-hydroxyethyl acrylate, add 0.75 mg of photoinitiator, ultrasonically mix for 5 min to obtain Solution B. Take 240 μL of Solution A and 120 μL of Solution B and mix them to obtain a pre-gel solution. Then add 2 mL of saturated LiCl solution to the pre-gel solution, mix it evenly by a rotary shaker, place it under a xenon lamp for photo-polymerization for 4 min. After the sample is completely polymerized, transfer it to an oven at 80 °C and dry it for 12 h to obtain a high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material, that is, a composite material containing P(AcH)-L gel substrate.

[0061] 3) According to the volume ratio of the photocatalytic layer gel substrate to the moisture absorption layer gel substrate being 0.5:1, place the photocatalytic layer gel substrate on the moisture absorption layer gel substrate. The moisture absorption layer gel substrate is located at the bottom layer, and the photocatalytic layer gel substrate is located at the top layer. The two are in contact to form a high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material.

[0062] Example 3

[0063] This example provides a preparation method of a high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material, and the steps are as follows:

[0064] 1) Disperse 15 mg of Ag / TiO2 in 1 mL of 2-hydroxyethyl acrylate (HEA) solution to obtain a pre-gel solution, add 1.5 mg of diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide photoinitiator, ultrasonically mix for 5 min, mix it evenly, place it under a xenon lamp for photo-polymerization for 1 min. After the sample is completely polymerized, transfer it to an oven at 80 °C and dry it completely to obtain a photocatalytic layer gel substrate, that is, 15-Ag / TiO2-P(HEA).

[0065] 2) Dissolve 0.5 g of acrylamide in 0.5 mL of water, ultrasonically disperse it evenly, add 0.75 mg of photoinitiator and ultrasonically mix it evenly to obtain Solution A. Then take 0.5 mL of 2-hydroxyethyl acrylate, add 0.75 mg of photoinitiator, ultrasonically mix for 5 min to obtain Solution B. Take 240 μL of Solution A and 120 μL of Solution B and mix them to obtain a pre-gel solution. Then add 2 mL of saturated LiCl solution to the pre-gel solution, mix it evenly by a rotary shaker, place it under a xenon lamp for photo-polymerization for 4 min. After the sample is completely polymerized, transfer it to an oven at 80 °C and dry it for 12 h to obtain a high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material, that is, a composite material containing P(AcH)-L gel substrate.

[0066] 3) According to the volume ratio of the photocatalytic layer gel substrate to the moisture absorption layer gel substrate being 0.5:1, place the photocatalytic layer gel substrate on the moisture absorption layer gel substrate. The moisture absorption layer gel substrate is located at the bottom layer, and the photocatalytic layer gel substrate is located at the top layer. The two are in contact to form a high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material.

[0067] Example 4

[0068] This example provides a preparation method for a high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material, and the steps are as follows:

[0069] 1) Disperse 10 mg of Ag / TiO2 in 1 mL of 2-hydroxyethyl acrylate (HEA) solution to obtain a pre-gel solution. Add 1.5 mg of diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide photoinitiator and ultrasonicate for 5 min, mix evenly, place it under a xenon lamp for light polymerization for 1 min. After the sample is completely polymerized, transfer it to an oven at 80 °C and dry it completely to obtain the photocatalytic layer gel substrate, namely Ag / TiO2-P(HEA).

[0070] 2) Dissolve 0.5 g of acrylamide in 0.5 mL of water and ultrasonically disperse it evenly. Add 0.75 mg of photoinitiator and ultrasonically mix evenly to obtain solution A. Then take 0.5 mL of 2-hydroxyethyl acrylate and add 0.75 mg of photoinitiator and ultrasonicate for 5 min, mix evenly to obtain solution B. Take 480 μL of solution A and 240 μL of solution B and mix them to obtain a pre-gel solution. Then add 2 mL of saturated LiCl solution to the pre-gel solution, mix it evenly by a rotary shaker, place it under a xenon lamp for light polymerization for 2 min. After the sample is completely polymerized, transfer it to an oven at 80 °C and dry it for 12 h to obtain a high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material, namely a 2P(AcH)-L gel substrate.

[0071] 3) According to the volume ratio of the photocatalytic layer gel substrate to the moisture absorption layer gel substrate being 0.5:1, place the photocatalytic layer gel substrate on the moisture absorption layer gel substrate. The moisture absorption layer gel substrate is located at the bottom layer, and the photocatalytic layer gel substrate is located at the top layer. The two are in contact to form a high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material.

[0072] Example 5

[0073] This example provides a preparation method for a high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material, and the steps are as follows:

[0074] 1) Disperse 20 mg of Ag / TiO₂ in 2 mL of 2-hydroxyethyl acrylate (HEA) solution to obtain a pre-gel solution. Add 3 mg of diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide photoinitiator and ultrasonicate for 5 min. Mix evenly, place it under a xenon lamp for photo-polymerization for 5 min. After the sample is completely polymerized, transfer it to an oven at 80 °C to completely dry it, obtaining a photocatalytic layer gel substrate, namely 20-Ag / TiO₂-P(HEA).

[0075] 2) Dissolve 0.5 g of acrylamide in 0.5 mL of water and ultrasonically disperse it evenly. Add 0.75 mg of photoinitiator and ultrasonically mix evenly to obtain solution A. Then take 0.5 mL of 2-hydroxyethyl acrylate, add 0.75 mg of photoinitiator and ultrasonicate for 5 min, mix evenly to obtain solution B. Take 480 μL of solution A and 240 μL of solution B and mix them to obtain a pre-gel solution. Then add 2 mL of saturated LiCl solution to the pre-gel solution, mix it evenly by a rotary shaker, place it under a xenon lamp for photo-polymerization for 5 min. After the sample is completely polymerized, transfer it to an oven at 80 °C and dry it for 12 h, obtaining a high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material, namely a composite material containing 2P(AcH)-L gel substrate.

[0076] 3) According to the volume ratio of the photocatalytic layer gel substrate to the moisture absorption layer gel substrate being 0.5:1, place the photocatalytic layer gel substrate on the moisture absorption layer gel substrate. The moisture absorption layer gel substrate is located at the bottom layer and the photocatalytic layer gel substrate is located at the top layer. The two are in contact to form a high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material.

[0077] Example 6

[0078] This example provides a preparation method of a high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material, and the steps are as follows:

[0079] 1) Disperse Ag / TiO₂ in 2 mL of 2-hydroxyethyl acrylate (HEA) solution to obtain a pre-gel solution. Add diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide photoinitiator and ultrasonicate for 10 min. Mix evenly, place it under a xenon lamp for photo-polymerization for 1 min. After the sample is completely polymerized, transfer it to an oven at 70 °C and dry it for 24 h, obtaining a photocatalytic layer gel substrate. Among them, the mass ratio of the photocatalyst to the HEA monomer is 1:100; the mass ratio of the photoinitiator to the HEA monomer is 0.2:100;

[0080] 2) Dissolve 0.5 g of acrylamide in 0.5 mL of water and disperse it evenly by ultrasonic treatment. Add 0.5 mg of photoinitiator and mix evenly by ultrasonic treatment to obtain Solution A. Then, according to the mass ratio of 2-hydroxyethyl acrylate to photoinitiator being 100:0.1, take 0.5 mL of 2-hydroxyethyl acrylate, add the photoinitiator, and perform ultrasonic treatment for 8 min to mix evenly, obtaining Solution B. Take 480 μL of Solution A and 240 μL of Solution B and mix them to obtain a pre-gel solution. Then, add 2 mL of saturated LiCl solution to the pre-gel solution, mix it evenly by a rotary shaker, place it under a xenon lamp for photo-polymerization for 1 min. After the sample is completely polymerized, transfer it to an oven at 85 °C for drying for 16 h to obtain a moisture-absorbing layer gel substrate.

[0081] 3) According to the volume ratio of the photocatalytic layer gel substrate to the moisture-absorbing layer gel substrate being 0.2:1, place the photocatalytic layer gel substrate on the moisture-absorbing layer gel substrate. The moisture-absorbing layer gel substrate is located at the bottom layer, and the photocatalytic layer gel substrate is located at the top layer. The two are in contact to form a high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material.

[0082] Example 7

[0083] This example provides a preparation method of a high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material, and the steps are as follows:

[0084] 1) Disperse Ag / TiO₂ in 2 mL of 2-hydroxyethyl acrylate (HEA) solution to obtain a pre-gel solution. Add diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide photoinitiator and perform ultrasonic treatment for 8 min to mix evenly. Place it under a xenon lamp for photo-polymerization for 3 min. After the sample is completely polymerized, transfer it to an oven at 90 °C for drying for 12 h to obtain a photocatalytic layer gel substrate. Among them, the mass ratio of the photocatalyst to the HEA monomer is 0.4:100; the mass ratio of the photoinitiator to the HEA monomer is 0.1:100;

[0085] 2) Dissolve 0.5 g of acrylamide in 0.5 mL of water and disperse it evenly by ultrasonic treatment. Add 1 mg of photoinitiator and mix evenly by ultrasonic treatment to obtain Solution A. Then, according to the mass ratio of 2-hydroxyethyl acrylate to photoinitiator being 100:0.2, take 0.5 mL of 2-hydroxyethyl acrylate, add the photoinitiator, and perform ultrasonic treatment for 2 min to mix evenly, obtaining Solution B. Take 480 μL of Solution A and 240 μL of Solution B and mix them to obtain a pre-gel solution. Then, add 2 mL of saturated LiCl solution to the pre-gel solution, mix it evenly by a rotary shaker, place it under a xenon lamp for photo-polymerization for 4 min. After the sample is completely polymerized, transfer it to an oven at 90 °C for drying for 12 h to obtain a moisture-absorbing layer gel substrate.

[0086] 3) Place the photocatalytic layer gel substrate on the moisture absorption layer gel substrate according to the volume ratio of the photocatalytic layer gel substrate to the moisture absorption layer gel substrate of 1:1. The moisture absorption layer gel substrate is located at the bottom layer, and the photocatalytic layer gel substrate is located at the top layer. The two are in contact to form a high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material.

[0087] Example 8

[0088] This example provides a preparation method for a high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material, and the steps are as follows:

[0089] 1) Disperse 20 mg of Ag / TiO2 in 2 mL of acrylic acid-2-hydroxyethyl acrylate (HEA) solution to obtain a pre-gel solution. Add 3 mg of diphenyl-(2,4,6-trimethylbenzoyl) phosphine oxide photoinitiator and ultrasonicate for 7 min. Mix evenly and place it under a xenon lamp for photo-polymerization for 4 min. After the sample is completely polymerized, transfer it to an oven at 75 °C and dry for 20 h to obtain the photocatalytic layer gel substrate. Among them, the mass ratio of the photocatalyst to the HEA monomer is 2:100; the mass ratio of the photoinitiator to the HEA monomer is 0.2:100;

[0090] 2) Dissolve 0.5 g of acrylamide in 0.5 mL of water and ultrasonically disperse it evenly. Add 0.9 mg of photoinitiator and ultrasonically mix evenly to obtain solution A. Then, according to the mass ratio of acrylic acid-2-hydroxyethyl acrylate to the photoinitiator of 100:0.15, take 0.5 mL of acrylic acid-2-hydroxyethyl acrylate and add the photoinitiator and ultrasonicate for 7 min. Mix evenly to obtain solution B. Take 800 μL of solution A and 400 μL of solution B and mix them to obtain a pre-gel solution. Then, add 2 mL of saturated LiCl solution to the pre-gel solution and mix it evenly by a rotary shaker. Place it under a xenon lamp for photo-polymerization for 10 min. After the sample is completely polymerized, transfer it to an oven at 70 °C and dry for 48 h to obtain the moisture absorption layer gel substrate.

[0091] 3) Place the photocatalytic layer gel substrate on the moisture absorption layer gel substrate according to the volume ratio of the photocatalytic layer gel substrate to the moisture absorption layer gel substrate of 0.7:1. The moisture absorption layer gel substrate is located at the bottom layer, and the photocatalytic layer gel substrate is located at the top layer. The two are in contact to form a high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material.

[0092] Comparative Example 1

[0093] This comparative example provides a preparation method for an air water intake hydrogel composite material, and the steps are as follows:

[0094] Dissolve 0.5 g of acrylamide in 0.5 mL of water and disperse it evenly by ultrasonic treatment. Add 0.75 mg of photoinitiator and mix evenly by ultrasonic treatment to obtain solution A. Then, take 0.5 mL of 2-hydroxyethyl acrylate, add 0.75 mg of photoinitiator, and mix evenly by ultrasonic treatment to obtain solution B. Take 240 μL of solution A and 120 μL of solution B and mix them to obtain a pre-gel solution. Then, add 2 mL of saturated LiCl solution to the pre-gel solution, mix it evenly with a rotary shaker, place it under a xenon lamp for photo-polymerization for 5 min. After the sample is completely polymerized, transfer it to an oven and dry it at 80 °C for 12 h to obtain a P(AcH)-L gel substrate containing material.

[0095] Comparative Example 2

[0096] This comparative example provides a preparation method for a photocatalytic hydrogen production hydrogel composite material, and the steps are as follows:

[0097] Disperse 10 mg of Ag / TiO2 in 1 mL of 2-hydroxyethyl acrylate (HEA) solution to obtain a pre-gel solution. Add 1.5 mg of diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide photoinitiator and mix evenly by ultrasonic treatment. Place it under a xenon lamp for photo-polymerization for 1 min. After the sample is completely polymerized, transfer it to an oven and dry it completely at 80 °C to obtain Ag-TiO2 / P(HEA).

[0098] As Figure 1 shown in (a) and (b) are the prepared photocatalytic layer Ag-TiO2 / P(HEA) of Comparative Example 2 and the moisture-absorbing layer P(AcH)-L hydrogel material of Comparative Example 1

[0099] As Figure 2 shown in (a) and (b) are the scanning electron microscope (SEM) images of P(AcH)-L and Ag-TiO2 in Sample Comparative Example 1. The P(AcH)-L samples all exhibit a loose porous structure and pore channels. Ag nanoparticles are loaded onto the surface of titanium dioxide through a photodeposition process to form Ag-TiO2, and SEM proves its uniform nanoparticles.

[0100] As Figure 3 shown, through the X-ray diffraction (XRD) pattern, it can be seen that there are obvious crystal characteristic peaks of LiCl and LiCl·H2O in the P(AcH)-L sample, which confirms that LiCl is successfully loaded in the P(AcH)-L matrix. In addition, the characteristic peaks of Ag-TiO2 can be clearly observed in the Ag-TiO2 / P(HEA) composite material, proving that the composite sample is successfully prepared.

[0101] As Figure 4As shown, the FT-IR spectra of Ag-TiO2 / P(HEA) and P(AcH)-L are highly similar, demonstrating that the addition of Ag-TiO2 does not significantly alter the hydrogel structure.

[0102] The following are the moisture absorption and hydrogen production performance tests for the air water harvesting-photocatalytic hydrogen production bifunctional integrated hydrogel composite material:

[0103] Example 9

[0104] Place the dried P(AcH)-L composite moisture absorption material in a thermostatic and humidistatic chamber, adjust the temperature to 25 °C, and the relative humidity (RH) to 30%, 60%, 70%, 90%. Test its mass change every 1 h and continuously test for 12 h.

[0105] As Figure 5 shown, the moisture absorption amounts of the P(AcH)-L composite moisture absorption material at 30% RH, 60% RH, 70% RH, and 90% RH are 1.50 g g -1 , 1.97 g g -1 , 2.50 g g -1 and 4.07 g g -1 , demonstrating that it still has high moisture absorption performance at relatively low humidity.

[0106] Example 10

[0107] Combine the photocatalytic layer Ag-TiO2 / P(HEA) hydrogel material with the P(AcH)-L composite moisture absorption material saturated at relative humidities (RH) of 30%, 60%, 70%, and 90% (AP-PL) respectively, and conduct photocatalytic water-hydrogen co-production activity tests under a xenon lamp simulating sunlight.

[0108] As Figure 6 shown, the moisture absorption ability of P(AcH)-L increases with the increase in the RH level, thereby enhancing its hydrogen production activity. Ag-TiO2 / P(HEA) quickly absorbs water vapor and greatly wets its surface. The H2 production rate of AP-PL is 0.7 mmol g at 30% relative humidity -1 . It should be noted that when saturated at 90% RH, the hydrogen production capacity of AP-PL is 2.1 mmol g -1 . This also verifies the feasibility of directly using the composite material to capture moisture from the air and further use the captured moisture to produce hydrogen under solar energy drive.

[0109] As Figure 7As shown, using only a photocatalytic layer and a moisture-absorbing layer has little activity for photocatalytic hydrogen production, indicating that photocatalytic hydrogen production occurs only when both the photocatalyst and water vapor are present. Additionally, when the moisture-absorbing layer and the photocatalytic layer hydrogel are immersed in liquid water, the H2 production rate drops to 0.5 mmol g -1 , demonstrating the necessity of constructing a biomimetic humidity gradient to promote gas-phase water transport, thereby enhancing the photocatalytic water vapor hydrogen production efficiency.

[0110] As Figure 8 shown, as the relative humidity (RH) increases from 30% to 90%, the desorption rate increases from 0.15 kg m -2 h -1 to 0.32 kg m -2 h -1 . This phenomenon can be attributed to the fact that after the hydrogel absorbs water and swells, the surface area exposed to the air increases, thus accelerating the evaporation kinetics. The AWH-PHE device is a closed chamber, so as the water vapor increases, the condensate water collection amount increases from 0.37 kg m -2 to 1.12 kg m -2 .

[0111] The preparation method of the present invention is more environmentally friendly and green on the basis of the existing preparation technology, and the process is simple and easy to operate. This method generates useful energy by absorbing moisture in the atmosphere and sunlight, solving the problem of obtaining water from the air while simultaneously carrying out photocatalytic hydrogen production, and opening up a new way for the development of photocatalytic hydrogen production in areas with sufficient light but water shortage.

[0112] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a composite material for high-humidity air water extraction and photocatalytic hydrogen water co-production, characterized in that, It includes the following steps: Subject the mixture containing Ag / TiO2, 2-hydroxyethyl acrylate and a photoinitiator to light-induced polymerization and drying to obtain a photocatalytic layer gel substrate; Mix the mixture containing acrylamide, water and a photoinitiator with the mixture containing 2-hydroxyethyl acrylate and a photoinitiator to obtain a pre-gel solution; Add a saturated LiCl solution to the pre-gel solution, mix evenly, then subject it to light-induced polymerization and drying to obtain a moisture-absorbing layer gel substrate; Place the photocatalytic layer gel substrate on the moisture-absorbing layer gel substrate to form a high-moisture-retention air water extraction-photocatalytic hydrogen water co-production composite material.

2. The preparation method of the high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material according to claim 1, characterized in that, The photoinitiator is diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide.

3. The preparation method of the high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material according to claim 1, characterized in that In the mixture containing acrylamide, water and a photoinitiator, the mass ratio of acrylamide to the photoinitiator is 100:0.1 - 0.

2.

4. The preparation method of the high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material according to claim 1, wherein, In the mixture containing Ag / TiO2, 2-hydroxyethyl acrylate and a photoinitiator, the mass ratio of 2-hydroxyethyl acrylate to the photoinitiator is 100:0.1 - 0.

2.

5. The preparation method of the high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material according to claim 1, wherein, The volume ratio of 2-hydroxyethyl acrylate to the saturated LiCl solution is 0.01 - 0.2:

1.

6. The preparation method of the high-moisture-retention air water extraction-photocatalytic hydrogen water co-production composite material according to claim 1, wherein, The volume ratio of the photocatalytic layer gel substrate to the moisture-absorbing layer gel substrate is 0.2 - 1:

1.

7. The preparation method of the high-moisture-retention air water extraction-photocatalytic hydrogen water co-production composite material according to claim 1, wherein, The mass ratio of Ag / TiO2 to 2-hydroxyethyl acrylate is 0.4 - 2:

100.

8. The preparation method of the high-moisture-retention air water intake-photocatalytic hydrogen water co-production composite material according to claim 1, characterized in that In the mixture containing 2-hydroxyethyl acrylate and a photoinitiator, the mass ratio of the photoinitiator to 2-hydroxyethyl acrylate is 0.1 - 0.2:100; the volume ratio of the mixture containing acrylamide, water and a photoinitiator to the mixture containing 2-hydroxyethyl acrylate and a photoinitiator is 2:

1.

9. A high-moisture-retention air water extraction-photocatalytic hydrogen water co-production composite material prepared by the method according to any one of claims 1 - 8.

10. Application of a high-moisture-retention air water extraction-photocatalytic hydrogen water co-production composite material prepared by the method according to any one of claims 1 - 8 in air water extraction-photocatalytic hydrogen production.

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