Composite photothermal evaporator based on hydrogenated molybdenum trioxide, preparation method and application

Abstract

This invention discloses a composite photothermal evaporator based on hydrogenated molybdenum trioxide, its preparation method, and its application, relating to the fields of clean energy and water resource utilization technology. The preparation method includes: performing a hydrogenation-reduction reaction of molybdenum trioxide powder and low work function metal particles in hydrochloric acid solution to obtain hydrogenated molybdenum trioxide powder and a filtrate containing metal ions; dispersing the hydrogenated molybdenum trioxide powder in the filtrate to obtain a composite dispersion; partially immersing the loading end of a polyvinyl alcohol foam substrate in a chitosan solution for pre-loading; then immersing the pre-loaded region in the composite dispersion to allow the chitosan to undergo an in-situ chelation reaction with the metal ions in the filtrate, simultaneously immobilizing the hydrogenated molybdenum trioxide particles; finally, subjecting the loading region to localized hydrophobic treatment to obtain a composite photothermal evaporator comprising a hydrophobic photothermal layer and a hydrophilic water-transporting layer. The evaporator obtained by this invention can be used for solar-powered seawater desalination, high-salinity wastewater treatment, or clean water production.

Description

Technical Field

[0001] This invention relates to the fields of clean energy and water resource utilization technology, and in particular to a composite photothermal evaporator based on hydrogenated molybdenum trioxide, its preparation method, and its application. Background Technology

[0002] Freshwater scarcity has become a global challenge hindering sustainable economic and social development. On the one hand, global freshwater resources account for only 3.5% of the Earth's total water volume; on the other hand, with accelerated industrialization and continuous population growth, the demand for industrial and domestic water has increased dramatically, further exacerbating the water supply-demand imbalance. Currently, seawater desalination and recycling are proposed as solutions to the water crisis. Among these, seawater reserves are enormous, and desalination is considered the most promising and effective means to increase freshwater supply. Existing seawater desalination technologies mainly include multi-stage flash evaporation, reverse osmosis, electrodialysis, and membrane distillation, but these technologies generally suffer from high energy consumption, high costs, and complex processes. In recent years, solar-driven interfacial photothermal evaporation technology has shown great potential in the field of clean water production due to its high efficiency and low energy consumption, attracting widespread attention.

[0003] Against this backdrop, designing efficient, stable, and low-cost photothermal evaporators has become crucial for driving the practical application of photothermal-driven interfacial evaporation technology. The core of a photothermal evaporator lies in the optimized design of the photothermal conversion material and the supporting structure: an ideal evaporator requires a photothermal layer with broad-band high absorption and efficient heat conversion capabilities, as well as a supporting layer with low thermal conductivity and hydrophilicity. Among numerous photothermal materials, molybdenum trioxide (MoO3) has attracted considerable attention due to its high chemical stability, low cost, and environmental friendliness. Although its band gap can be significantly improved through defect engineering or impurity doping, limitations remain in evaporator construction. Existing research often uses traditional substrates such as cleanroom paper and fabrics as supporting materials, resulting in relatively simple structural designs and weak bonding between the photothermal material and the substrate. This makes it prone to detachment during long-term water flow and evaporation cycles, severely limiting its practical application lifespan. Achieving stable loading of photothermal components on porous substrates often relies on adding external adhesives, which not only increases process complexity but also often embeds photothermal active sites and blocks water molecule transport channels, reducing evaporation efficiency.

[0004] Therefore, this study aims to develop a new preparation strategy to construct a composite photothermal evaporator with high photothermal conversion efficiency, excellent water transport performance, and high stability, thereby meeting the needs of practical applications. Summary of the Invention

[0005] Based on the technical problems existing in the background technology, this invention proposes a composite photothermal evaporator based on hydrogenated molybdenum trioxide, its preparation method and application. This composite photothermal evaporator has the advantages of strong absorption in a wide spectrum, high efficiency in photothermal conversion, excellent anti-salt blockage performance and excellent structural stability. It is suitable for multiple practical application fields such as solar-driven seawater desalination and treatment of saline industrial wastewater, and has a high degree of functional integration advantage and broad industrialization prospects.

[0006] This invention proposes a method for preparing a composite photothermal evaporator based on hydrogenated molybdenum trioxide, the method steps of which are as follows:

[0007] S1: Molybdenum trioxide powder is mixed with metal particles and placed in hydrochloric acid solution for hydrogenation reduction reaction. After the reaction is completed, solid-liquid separation is performed. The obtained solid is washed and dried to obtain hydrogenated molybdenum trioxide powder. The obtained filtrate is used for later use.

[0008] S2: Disperse the hydrogenated molybdenum trioxide powder in the filtrate using ultrasonication to obtain a dispersion;

[0009] S3: Immerse the end of the polyvinyl alcohol foam to be loaded into the chitosan solution to obtain polyvinyl alcohol foam loaded with chitosan;

[0010] S4: The polyvinyl alcohol foam loaded with chitosan is chelated in a dispersion to obtain a photothermal loading layer;

[0011] S5: The photothermal load layer is hydrophobically treated so that the hydrophobically treated load area forms a hydrophobic photothermal layer, and the remaining area is a hydrophilic water transport layer, thus obtaining a composite photothermal evaporator.

[0012] Preferably, S1 contains one or more of the following metal particles: zinc, aluminum, and iron.

[0013] And / or, the mass ratio of molybdenum trioxide powder to metal particles is 1:1-3.

[0014] Preferably, the conditions for the hydrogenation reduction reaction in S1 are a temperature of 20-40°C and a time of 4-12 hours.

[0015] Preferably, the mass ratio of hydrogenated molybdenum trioxide powder to filtrate in S2 is 1:5-10.

[0016] Preferably, the chitosan solution concentration in S3 is 0.5-2 wt%, and the solvent is an aqueous solution of acetic acid with a volume fraction of 1-3%.

[0017] Preferably, the chelation reaction conditions in S4 are a temperature of 20-60℃ and a time of 4-12h.

[0018] Preferably, the hydrophobic treatment in S5 is performed using a polydimethylsiloxane solution containing a curing agent;

[0019] And / or, the mass ratio of the polydimethylsiloxane, solvent, and curing agent is 1:3-5:0.05-0.15;

[0020] And / or, the solvent is one or more of cyclohexane, n-hexane, and isopropanol.

[0021] The present invention proposes a composite photothermal evaporator based on hydrogenated molybdenum trioxide, which is prepared by the above-mentioned method.

[0022] Preferably, the hydrophobic photothermal layer has a water contact angle in the air greater than or equal to 110°, and the hydrophilic water-transporting layer absorbs and wets water in the air.

[0023] The present invention proposes the application of the composite photothermal evaporator based on hydrogenated molybdenum trioxide as described above in solar seawater desalination, high-salinity wastewater treatment, or clean water production.

[0024] Beneficial technical effects of the present invention:

[0025] (1) This invention utilizes molybdenum trioxide (MoO3) as the core component for photothermal conversion. Through low work function metal-induced acidic hydrogenation treatment, a high concentration of hydrogen atoms is effectively introduced to achieve its spectral modification. The hydrogenated molybdenum trioxide exhibits excellent light absorption characteristics in the ultraviolet-visible-near-infrared band, with an absorption rate of over 95%. Moreover, this method has significant advantages such as simple process route, inexpensive and readily available raw materials, and no need for complex high-temperature and high-pressure hydrogenation treatment process, which greatly reduces the energy consumption of preparation.

[0026] (2) This invention creatively utilizes metal ions, a byproduct of hydrogenation reaction, as a key chelating agent to achieve in-situ stable loading of photothermal materials. First, the metal ions undergo an in-situ chelation reaction with chitosan molecules pre-loaded on the polyvinyl alcohol foam skeleton to construct a dense hybrid network that is insoluble in water, firmly anchoring the hydrogenated molybdenum trioxide particles to the skeleton surface. This fundamentally solves the problem of photothermal materials falling off in an aqueous environment and significantly improves the structural durability of the evaporator. Second, this strategy does not require the addition of crosslinking agents or binders, simplifying the preparation process while realizing the resource recycling of byproducts, thus possessing the dual core advantages of process simplification and green environmental protection.

[0027] (3) The Janus asymmetric wetting structure of "hydrophobic photothermal layer / hydrophilic water transport layer" constructed in this invention realizes multiple synergistic effects of heat-mass regulation. While achieving efficient photothermal conversion, the hydrophobic photothermal layer can effectively block the migration of salt carried by water to the material surface, thus avoiding the accumulation and crystallization of salt on the photothermal surface during evaporation from a physical perspective; the pure polyvinyl alcohol hydrophilic water transport layer, relying on its intrinsic hydrophilic properties and three-dimensional interconnected pore structure, ensures continuous and efficient water transport at the evaporation interface, realizing efficient evaporation with low heat loss.

[0028] In summary, the hydrogenated molybdenum trioxide / polyvinyl alcohol foam composite photothermal evaporator constructed in this invention has the advantages of broad-spectrum strong absorption, high-efficiency photothermal conversion, excellent anti-salt blockage performance and excellent structural stability. It is suitable for multiple practical application fields such as solar-driven seawater desalination and treatment of saline industrial wastewater, and has a high degree of functional integration advantage and broad industrialization prospects. Attached Figure Description

[0029] Figure 1 This is a process flow diagram of the fabrication process of the composite photothermal evaporator proposed in this invention;

[0030] Figure 2 The following are physical images of the composite photothermal evaporator proposed in this invention; wherein (a) is a top view of the composite photothermal evaporator prepared in Example 1, (b) is a top view of the polyvinyl alcohol foam, (c) is a side view of the composite photothermal evaporator prepared in Example 1, and (d) is a side view of the polyvinyl alcohol foam.

[0031] Figure 3 The ultraviolet-visible-near-infrared absorption spectra of the polyvinyl alcohol foam, hydrogenated molybdenum trioxide, and composite photothermal evaporator proposed in this invention are shown below.

[0032] Figure 4 These are scanning electron microscope (SEM) images of the composite photothermal evaporator proposed in this invention; where (a) is untreated molybdenum trioxide powder, (b) is hydrogenated molybdenum trioxide powder, (c) is the cross-section of untreated polyvinyl alcohol foam, (d) is the cross-section of the composite photothermal evaporator of Example 1, (e) is the cross-section of the hydrophobic photothermal layer of the composite photothermal evaporator of Example 1 at a size of 2 μm, and (f) is the cross-section of the hydrophobic photothermal layer of the composite photothermal evaporator of Example 1 at a size of 400 nm;

[0033] Figure 5 The water contact angle in air for the composite photothermal evaporator proposed in this invention; wherein (a) is the hydrophobic photothermal layer of the composite photothermal evaporator of Example 1, and (b) is the hydrophilic water-conducting layer of the composite photothermal evaporator of Example 1;

[0034] Figure 6 The infrared temperature change of the composite photothermal evaporator proposed in this invention under 1 hour of sunlight irradiation; wherein (a) is the surface temperature of polyvinyl alcohol foam before evaporation test, (b) is the surface temperature of the composite photothermal evaporator of Example 1 before evaporation test, (c) is the surface temperature of polyvinyl alcohol foam after 30 minutes of evaporation test, (d) is the surface temperature of the composite photothermal evaporator of Example 1 after 30 minutes of evaporation test, (e) is the surface temperature of polyvinyl alcohol foam after 60 minutes of evaporation test, and (f) is the surface temperature of the composite photothermal evaporator of Example 1 after 60 minutes of evaporation test;

[0035] Figure 7 The evaporation effect of the composite photothermal evaporator proposed in this invention;

[0036] In the diagram: 1-Hydrophobic photothermal layer, 2-Hydrophilic water transport layer. Detailed Implementation

[0037] The present invention will be further explained below with reference to specific embodiments.

[0038] Example 1

[0039] See Figure 1 The preparation of a composite photothermal evaporator based on hydrogenated molybdenum trioxide and polyvinyl alcohol foam includes metal-acid hydrogenation, dispersion, loading, and hydrophobic treatment. The resulting evaporator has an asymmetric structure, consisting of a hydrophobic photothermal layer and a hydrophilic water-transporting layer from top to bottom. The specific steps are as follows:

[0040] Metal-acid hydrogenation: Weigh 10g of molybdenum trioxide powder and disperse it in 200mL of 4mol / L hydrochloric acid solution. Slowly add 10g of zinc particles with a particle size of about 1mm. Stir the mixture magnetically at room temperature for 12h. Filter to remove unreacted zinc particles to obtain black molybdenum trioxide powder and filtrate containing zinc ions.

[0041] Dispersion: Take 1g of black molybdenum trioxide powder and mix it with 5g of zinc ion-containing filtrate, and then sonicate for 30 minutes to form a stable dispersion.

[0042] Loading: Weigh 1g of chitosan and add it to 100mL of a 2% (w / w) acetic acid aqueous solution. Stir magnetically until completely dissolved to obtain a chitosan solution. Cut 2cm thick polyvinyl alcohol foam into 3cm × 3cm × 2cm cubes, ultrasonically clean with deionized water for 15 minutes, and dry at 60℃ for later use. Use the top 0.5cm thick area of ​​the foam as the photothermal loading zone, immerse it in the chitosan solution to obtain chitosan-loaded foam. Immerse the obtained chitosan-loaded foam in a composite dispersion and squeeze it three times to promote the penetration and diffusion of the dispersion into the photothermal loading zone. During this process, the chitosan on the foam skeleton in the photothermal loading zone undergoes a chelation reaction with zinc ions in the solution (controlled reaction temperature at 40℃, time 8h), forming a hydrogel network, while simultaneously coating and fixing hydrogenated molybdenum trioxide particles onto the skeleton.

[0043] Hydrophobic treatment: 10g of polydimethylsiloxane prepolymer and 1g of curing agent were added to 44g of n-hexane solution and stirred thoroughly. The loaded area of ​​the above foam was immersed in the solution for 30 minutes, and then heated in an oven at 60℃ for hydrophobic curing for 24 hours to obtain a composite photothermal interface evaporator with a hydrophilic water-conducting layer and a hydrophobic photothermal layer. Figure 2 ).

[0044] The hydrophilic water-conducting layer is 1.5cm thick untreated polyvinyl alcohol foam.

[0045] The hydrophobic photothermal layer consists of a 0.5cm thick polyvinyl alcohol foam skeleton, encapsulating hydrogenated molybdenum trioxide and chitosan-zinc chelate, with the surface treated with polydimethylsiloxane for hydrophobicity.

[0046] Structural testing: Figure 3 A comparison of the UV-Vis-NIR spectra of untreated molybdenum trioxide powder, hydrogenated molybdenum trioxide powder, polyvinyl alcohol foam, and the composite photothermal interface water evaporator prepared in Example 1 shows that hydrogenation treatment improves the light absorption capacity of molybdenum trioxide powder in the wavelength range of 300–2500 nm, and the evaporator loaded with hydrogenated molybdenum trioxide shows approximately 95% spectral absorption. Figure 4 SEM images of molybdenum trioxide powder, hydrogenated molybdenum trioxide powder prepared in Example 1, and the composite photothermal interface water evaporator are shown. The molybdenum trioxide powder has a plate-like structure, and the hydrogenated molybdenum trioxide powder is more prone to agglomeration. The evaporator shows a clear boundary. The hydrophilic water transport layer has interconnected irregular pores with a pore size of 100-150 μm, while the hydrophobic photothermal layer has sparse pores and a dense accumulation of hydrogenated molybdenum trioxide powder on its surface. Figure 5 The water contact angle of the two layers of the composite photothermal interface water evaporator prepared in Example 1 in the air is approximately 117° for the hydrophobic photothermal layer and cannot be measured for the hydrophilic water transport layer due to water absorption and wetting.

[0047] Evaporation performance test: A certain amount of 3.5wt% sodium chloride solution was placed in a 100mL beaker, and the insulating foam and evaporator were then placed inside, with the mass recorded. The intensity of the solar simulator was 1.0kW / m². 2 Mass loss was recorded every 3 minutes, and temperature changes were recorded using an infrared camera at 0s, 30min, and 60min. Figure 6 As shown, under irradiation at a standard solar intensity, the surface temperature of the evaporator prepared in Example 1 was approximately 30°C higher than that of pure polyvinyl alcohol foam. Figure 7 As shown, the evaporator prepared in Example 1 exhibits excellent evaporation performance, with an evaporation rate reaching 1.04 kg·m³. -2 ·h -1 .

[0048] Example 2

[0049] See Figure 1 The preparation of a composite photothermal evaporator based on hydrogenated molybdenum trioxide and polyvinyl alcohol foam includes metal-acid hydrogenation, dispersion, loading and water treatment. Its structure consists of a hydrophilic water supply layer and a hydrophobic photothermal layer from bottom to top.

[0050] Metal-acid hydrogenation: Weigh 10g of molybdenum trioxide powder and disperse it in 200mL of 4mol / L hydrochloric acid solution. Slowly add 10g of aluminum particles with a particle size of about 1mm. Stir the mixture magnetically at room temperature for 12h. Filter to remove unreacted aluminum particles to obtain black molybdenum trioxide powder and filtrate containing aluminum ions.

[0051] Dispersion: Take 1g of black molybdenum trioxide powder and mix it with 5g of aluminum ion-containing filtrate, and then sonicate for 30 minutes to form a stable dispersion.

[0052] Loading: Weigh 1g of chitosan and add it to 100mL of a 2% (w / w) acetic acid aqueous solution. Stir magnetically until completely dissolved to obtain a chitosan solution. Cut 2cm thick polyvinyl alcohol foam into 3cm × 3cm × 2cm cubes, ultrasonically clean with deionized water for 15 minutes, and dry at 60℃ for later use. Use the top 0.5cm thick area of ​​the foam as the photothermal loading zone, immerse it in the chitosan solution to obtain chitosan-loaded foam. Immerse the obtained chitosan-loaded foam in a composite dispersion and squeeze it three times to promote the penetration and diffusion of the dispersion into the photothermal loading zone. During this process, the chitosan on the foam skeleton in the photothermal loading zone undergoes a chelation reaction with aluminum ions in the solution (reaction temperature controlled at 40℃, time 8h), forming a hydrogel network, while simultaneously coating and fixing hydrogenated molybdenum trioxide particles onto the skeleton.

[0053] Hydrophobic treatment: 10g of polydimethylsiloxane prepolymer and 1g of curing agent were added to 44g of n-hexane solution and stirred thoroughly. The loaded area of ​​the above foam was immersed in the solution for 30 minutes and then heated in an oven at 60℃ for 24 hours to cure hydrophobically, thus obtaining a composite photothermal interface evaporator with a hydrophilic water-conducting layer and a hydrophobic photothermal layer.

[0054] The hydrophilic water-conducting layer is 1.5cm thick untreated polyvinyl alcohol foam.

[0055] The hydrophobic photothermal layer consists of a 0.5cm thick polyvinyl alcohol foam skeleton, encapsulating hydrogenated molybdenum trioxide and chitosan-aluminum chelate, with the surface treated with polydimethylsiloxane for hydrophobicity.

[0056] Example 3

[0057] See Figure 1 The preparation of a composite photothermal evaporator based on hydrogenated molybdenum trioxide and polyvinyl alcohol foam includes metal-acid hydrogenation, dispersion, loading and water treatment. Its structure consists of a hydrophilic water supply layer and a hydrophobic photothermal layer from bottom to top.

[0058] Metal-acid hydrogenation: Weigh 10g of molybdenum trioxide powder and disperse it in 200mL of 2mol / L hydrochloric acid solution. Slowly add 10g of zinc particles with a particle size of about 1mm. Stir the mixture magnetically at room temperature for 12h. Filter to remove unreacted zinc particles to obtain black molybdenum trioxide powder and filtrate containing zinc ions.

[0059] Dispersion: Take 1g of black molybdenum trioxide powder and mix it with 5g of zinc ion-containing filtrate, and then sonicate for 30 minutes to form a stable dispersion.

[0060] Loading: Weigh 1g of chitosan and add it to 100mL of a 2% (w / w) acetic acid aqueous solution. Stir magnetically until completely dissolved to obtain a chitosan solution. Cut 2cm thick polyvinyl alcohol foam into 3cm × 3cm × 2cm cubes, ultrasonically clean with deionized water for 15 minutes, and dry at 60℃ for later use. Use the top 0.5cm thick area of ​​the foam as the photothermal loading zone, immerse it in the chitosan solution to obtain chitosan-loaded foam. Immerse the obtained chitosan-loaded foam in a composite dispersion and squeeze it three times to promote the penetration and diffusion of the dispersion into the photothermal loading zone. During this process, the chitosan on the foam skeleton in the photothermal loading zone undergoes a chelation reaction with zinc ions in the solution (controlled reaction temperature at 40℃, time 8h), forming a hydrogel network, while simultaneously coating and fixing hydrogenated molybdenum trioxide particles onto the skeleton.

[0061] Hydrophobic treatment: 10g of polydimethylsiloxane prepolymer and 1g of curing agent were added to 33g of n-hexane solution and stirred thoroughly. The loaded area of ​​the above foam was immersed in the solution for 30 minutes and then heated in an oven at 60℃ for 24 hours to cure hydrophobically, thus obtaining a composite photothermal interface evaporator with a hydrophilic water-conducting layer and a hydrophobic photothermal layer.

[0062] The hydrophilic water-conducting layer is 1.5cm thick untreated polyvinyl alcohol foam.

[0063] The hydrophobic photothermal layer consists of a 0.5cm thick polyvinyl alcohol foam skeleton, encapsulating hydrogenated molybdenum trioxide and chitosan-zinc chelate, with the surface treated with polydimethylsiloxane for hydrophobicity.

[0064] Comparative Example 1

[0065] See Figure 1 The preparation of a composite photothermal evaporator based on hydrogenated molybdenum trioxide and polyvinyl alcohol foam includes metal-acid hydrogenation, dispersion, loading, and hydrophobic treatment. The resulting evaporator has an asymmetric structure, consisting of a hydrophobic photothermal layer and a hydrophilic water-transporting layer from top to bottom. The specific steps are as follows:

[0066] Metal-acid hydrogenation: Weigh 10g of molybdenum trioxide powder and disperse it in 200mL of 4mol / L hydrochloric acid solution. Slowly add 10g of zinc particles with a particle size of about 1mm. Stir the mixture magnetically at room temperature for 12h. Filter to remove unreacted zinc particles to obtain black molybdenum trioxide powder.

[0067] Dispersion: Take 10g of zinc granules with a particle size of about 1mm, slowly add 200mL of 4mol / L hydrochloric acid solution, and stir magnetically at room temperature for 12h to obtain zinc chloride solution. Take 1g of black molybdenum trioxide powder and mix with 5g of zinc chloride solution, and sonicate for 30 minutes to form a stable dispersion.

[0068] Loading: Weigh 1g of chitosan and add it to 100mL of a 2% (w / w) acetic acid aqueous solution. Stir magnetically until completely dissolved to obtain a chitosan solution. Cut 2cm thick polyvinyl alcohol foam into 3cm × 3cm × 2cm cubes, ultrasonically clean with deionized water for 15 minutes, and dry at 60℃ for later use. Use the top 0.5cm thick area of ​​the foam as the photothermal loading zone, immerse it in the chitosan solution to obtain chitosan-loaded foam. Immerse the obtained chitosan-loaded foam in a composite dispersion and squeeze it three times to promote the penetration and diffusion of the dispersion into the photothermal loading zone. During this process, the chitosan on the foam skeleton in the photothermal loading zone undergoes a chelation reaction with zinc ions in the solution (controlled reaction temperature at 40℃, time 8h), forming a hydrogel network, while simultaneously coating and fixing hydrogenated molybdenum trioxide particles onto the skeleton.

[0069] Hydrophobic treatment: 10g of polydimethylsiloxane prepolymer and 1g of curing agent were added to 44g of n-hexane solution and stirred thoroughly. The loaded area of ​​the above foam was immersed in the solution for 30 minutes, and then heated in an oven at 60℃ for hydrophobic curing for 24 hours to obtain a composite photothermal interface evaporator with a hydrophilic water-conducting layer and a hydrophobic photothermal layer. Figure 2 ).

[0070] The hydrophilic water-conducting layer is 1.5cm thick untreated polyvinyl alcohol foam.

[0071] The hydrophobic photothermal layer consists of a 0.5cm thick polyvinyl alcohol foam skeleton, encapsulating hydrogenated molybdenum trioxide and chitosan-zinc chelate, with the surface treated with polydimethylsiloxane for hydrophobicity.

[0072] Evaporation performance test: A certain amount of 3.5wt% sodium chloride solution was placed in a 100mL beaker, and the insulating foam and evaporator were then placed inside, with the mass recorded. The intensity of the solar simulator was 1.0kW / m². 2 The mass loss is recorded every 3 minutes. For example... Figure 7 As shown, in terms of evaporation performance, the evaporator prepared in Comparative Example 1 has an evaporation rate of approximately 0.94 kg·m³. -2 ·h-1 The evaporation rate was lower than that of Example 1 (1.04 kg·m³). -2 ·h -1 ).

[0073] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application. The scope of this application is defined by the appended claims and their equivalents, all of which should be included within the protection scope of this application.

Claims

1. A method for preparing a composite photothermal evaporator based on hydrogenated molybdenum trioxide, characterized in that, The steps are as follows: S1: Molybdenum trioxide powder is mixed with metal particles and placed in hydrochloric acid solution for hydrogenation reduction reaction. After the reaction is completed, solid-liquid separation is performed. The obtained solid is washed and dried to obtain hydrogenated molybdenum trioxide powder. The obtained filtrate is used for later use. S2: Disperse the hydrogenated molybdenum trioxide powder in the filtrate using ultrasonication to obtain a dispersion; S3: Immerse the end of the polyvinyl alcohol foam to be loaded into the chitosan solution to obtain polyvinyl alcohol foam loaded with chitosan; S4: The polyvinyl alcohol foam loaded with chitosan is chelated in a dispersion to obtain a photothermal loading layer; S5: The photothermal load layer is hydrophobically treated so that the hydrophobically treated load area forms a hydrophobic photothermal layer, and the remaining area is a hydrophilic water transport layer, thus obtaining a composite photothermal evaporator.

2. The method for preparing a composite photothermal evaporator based on hydrogenated molybdenum trioxide according to claim 1, characterized in that, S1 contains one or more of the following metal particles: zinc, aluminum, and iron. And / or, the mass ratio of molybdenum trioxide powder to metal particles is 1:1-3.

3. The method for preparing a composite photothermal evaporator based on hydrogenated molybdenum trioxide according to claim 1, characterized in that, The conditions for the hydrogenation reduction reaction in S1 are a temperature of 20-40℃ and a time of 4-12h.

4. The method for preparing a composite photothermal evaporator based on hydrogenated molybdenum trioxide according to claim 1, characterized in that, The mass ratio of hydrogenated molybdenum trioxide powder to filtrate in S2 is 1:5-10.

5. The method for preparing a composite photothermal evaporator based on hydrogenated molybdenum trioxide according to claim 1, characterized in that, The chitosan solution in S3 has a concentration of 0.5-2 wt%, and the solvent is an aqueous solution of acetic acid with a volume fraction of 1-3%.

6. The method for preparing a composite photothermal evaporator based on hydrogenated molybdenum trioxide according to claim 1, characterized in that, The chelation reaction conditions in S4 are a temperature of 20-60℃ and a time of 4-12h.

7. The method for preparing a composite photothermal evaporator based on hydrogenated molybdenum trioxide according to claim 1, characterized in that, The hydrophobic treatment in S5 is carried out using a polydimethylsiloxane solution containing a curing agent; And / or, the mass ratio of the polydimethylsiloxane, solvent, and curing agent is 1:3-5:0.05-0.15; And / or, the solvent is one or more of cyclohexane, n-hexane, and isopropanol.

8. A composite photothermal evaporator based on hydrogenated molybdenum trioxide, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

9. The composite photothermal evaporator based on hydrogenated molybdenum trioxide according to claim 8, characterized in that, The hydrophobic photothermal layer has a water contact angle in the air greater than or equal to 110°, and the hydrophilic water-transporting layer absorbs and wets water in the air.

10. The application of the composite photothermal evaporator based on hydrogenated molybdenum trioxide as described in claim 8 or 9 in solar seawater desalination, high-salinity wastewater treatment, or clean water production.

Images