Solar-driven interfacial evaporator and method of making the same

Abstract

The application discloses a solar-driven interfacial evaporator and a preparation method thereof. First, a silver nanowire ethylene glycol concentrated solution and sodium carbonate powder are pressed into a tablet, low-temperature sintering and dissolution are performed to obtain a silver nanowire porous body, and then laser treatment is performed to pyrolyze polyvinylpyrrolidone wrapped on the surface of the silver nanowire into nanocarbon, so as to obtain a super-hydrophobic silver nanowire and nanocarbon composite layer. The solar-driven interfacial evaporator disclosed by the application uses the nanocarbon composite layer wrapped on the surface of the silver nanowire as an absorption layer, and the absorption layer is firm and can absorb full-spectrum solar energy. The silver nanowire porous body with a fibrous pore structure has good mechanical properties, high flux and strong stain resistance.

Description

Technical Field

[0001] This invention belongs to the field of new materials, specifically relating to a solar-driven interface evaporator and its preparation method. Background Technology

[0002] Water scarcity is a global problem, and seawater desalination is an effective way to solve this problem. Traditional solar-driven bulk evaporation has low energy utilization. To effectively improve water evaporation efficiency, researchers have designed a solar-driven interfacial water evaporation technology that fixes the collected heat at the water-air interface, allowing most of the heat to be used for liquid-gas phase change and reducing heat loss. The entire process of solar-driven interfacial evaporation mainly includes: 1) Incident sunlight is absorbed by the light-absorbing layer of the evaporator and converted into heat; 2) Under capillary action, water is transported from the bottom of the evaporator substrate to the light-absorbing layer; 3) The light-absorbing layer heats the water molecules on the evaporation surface and generates steam; 4) After evaporation and condensation, the steam flows to the collection tank, achieving the collection of fresh water. The photothermal material placed on the surface of the device can effectively collect sunlight and convert it into heat, providing energy for water evaporation. The porous substrate material inside the device, while transporting water, relies on its excellent thermal insulation properties to greatly reduce heat loss, thus achieving efficient water evaporation. Compared with traditional seawater desalination technology, this technology has advantages in evaporation efficiency, clean energy utilization, and environmental friendliness. Therefore, solar-driven interfacial evaporation technology is a promising method to solve the shortage of freshwater resources.

[0003] Chinese patent application number CN2021107551630 discloses a self-healing hydrophilic porous photothermal film, its preparation method and application, which uses carbon-based photothermal materials and polyurethane hydrophilic porous materials to make a porous photothermal film.

[0004] Chinese patent application number CN2021112322260 discloses a porous hydrophilic photothermal seawater desalination composite membrane and its preparation method. The composite membrane includes a light absorption layer, a thermal management layer, and a water transport layer. The water transport layer is a polyacrylonitrile film, the thermal management layer is an epoxy resin film doped with carbon nanotubes, and the light absorption layer is a silicon carbide / silicon nitride film.

[0005] Existing solar-driven interface water evaporators generally suffer from drawbacks such as weak antifouling performance, poor durability, low strength, low flux of porous materials for transporting water, and weak bonding of solar energy absorbing materials, making them prone to loss. Summary of the Invention

[0006] The purpose of this invention is to provide a solar-driven interface evaporator and its preparation method to solve the problems mentioned in the background art. One of the purposes of this invention is to provide a solar-driven interface evaporator: the solar-driven interface evaporator of this application includes a porous body with a silver nanowire structure and a superhydrophobic silver nanowire and nano-carbon composite layer that is firmly bonded to the surface of the porous body, and the composite layer serves as a solar energy absorption layer. Another object of the present invention provides a method for preparing the above-mentioned solar-driven interfacial evaporator, comprising the following steps: Step 1, centrifuging and concentrating a silver nanowire ethylene glycol dispersion prepared by the polyol method, and adjusting the concentration to 1wt% to 10wt%; Step 2, adding sodium carbonate powder with a particle size of 10nm to 1μm to the centrifuged ethylene glycol silver nanowire concentrate and mixing well, wherein the amount of sodium carbonate added is 0.5 to 2 times the silver content; Step 3, pressing the mixed sample into tablets using a tablet press at a pressure of 5 to 20MPa; Step 4, sintering the tableted sample in muffle furnace at 240℃ to 330℃; Step 5, dissolving the sodium carbonate in water to obtain a porous body with a silver nanowire structure; Step 6, treating the surface of the porous body with a laser to cause in-situ pyrolysis of the polyvinylpyrrolidone coating silver on the surface of the silver nanowires to obtain a superhydrophobic layer containing nano-carbon materials. The solar-driven interfacial evaporator is thus prepared through the above steps.

[0007] Beneficial effects: The solar-driven interface evaporator prepared in this application has a fibrous porous structure with silver nanowire architecture, which has high flux, strong anti-fouling ability, small pore size that is not easily blocked by salt, and good mechanical properties. Attached Figure Description

[0008] Figure 1 Optical micrographs of silver nanowires used in this application.

[0009] Figure 2 This is a contact angle diagram of the porous body of the silver nanowire architecture in Embodiment 4 of this application. Detailed Implementation

[0010] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are still within the scope of protection of the present invention.

[0011] Example 1:

[0012] A solar-driven interface evaporator: The solar-driven interface evaporator of this application comprises a porous body with a silver nanowire structure and a superhydrophobic silver nanowire and nano-carbon composite layer firmly bonded to the surface of the porous body, serving as a solar energy absorption layer. The preparation method of this evaporator includes the following steps: Step 1, centrifuging and concentrating a silver nanowire ethylene glycol dispersion prepared by a polyol method, and adjusting the concentration to 1 wt%; Step 2, adding sodium carbonate powder with a particle size of 1 μm to the centrifuged ethylene glycol silver nanowire concentrate and mixing thoroughly, the amount of sodium carbonate added being twice the silver content; Step 3, pressing the mixed sample into tablets using a tablet press at a pressure of 5 MPa; Step 4, sintering the tableted sample in muffle furnace at 240°C; Step 5, dissolving the sodium carbonate in water to obtain a porous body with a silver nanowire structure; Step 6, treating the surface of the porous body with a laser to cause in-situ pyrolysis of the polyvinylpyrrolidone coating the silver on the surface of the silver nanowires, obtaining a superhydrophobic layer containing nano-carbon materials. The solar-driven interface evaporator prepared by the above method has a strength of 2 MPa, a porosity of 92%, a pore size of 1 μm, and a contact angle of 153.7 degrees between the surface solar absorption layer and water.

[0013] Example 2:

[0014] A solar-driven interface evaporator: The solar-driven interface evaporator of this application comprises a porous body with a silver nanowire structure and a superhydrophobic silver nanowire and nano-carbon composite layer firmly bonded to the surface of the porous body, serving as a solar energy absorption layer. The preparation method of this evaporator includes the following steps: Step 1, centrifuging and concentrating a silver nanowire ethylene glycol dispersion prepared by a polyol method, and adjusting the concentration to 3 wt%; Step 2, adding sodium carbonate powder with a particle size of 300 nm to the centrifuged ethylene glycol silver nanowire concentrate and mixing thoroughly, the amount of sodium carbonate added being 1.5 times the silver content; Step 3, pressing the mixed sample into tablets using a tablet press at a pressure of 7 MPa; Step 4, sintering the tableted sample in muffle furnace at 260°C; Step 5, dissolving the sodium carbonate in water to obtain a porous body with a silver nanowire structure; Step 6, treating the surface of the porous body with a laser to cause in-situ pyrolysis of the polyvinylpyrrolidone coating the silver on the surface of the silver nanowires, obtaining a superhydrophobic layer containing nano-carbon materials. The solar-driven interface evaporator prepared by the above method has a strength of 2.8 MPa, a porosity of 89%, a pore size of 300 nm, and a contact angle of 152.9 degrees between the surface solar absorption layer and water.

[0015] Example 3:

[0016] A solar-driven interface evaporator: The solar-driven interface evaporator of this application comprises a porous body with a silver nanowire structure and a superhydrophobic silver nanowire and nano-carbon composite layer firmly bonded to the surface of the porous body, serving as a solar energy absorption layer. The preparation method of this evaporator includes the following steps: Step 1, centrifuging and concentrating a silver nanowire ethylene glycol dispersion prepared by a polyol method, and adjusting the concentration to 5 wt%; Step 2, adding sodium carbonate powder with a particle size of 100 nm to the centrifuged ethylene glycol silver nanowire concentrate and mixing thoroughly, the amount of sodium carbonate added being 1 times the silver content; Step 3, pressing the mixed sample into a tablet using a tablet press at a pressure of 9 MPa; Step 4, sintering the tableted sample in a muffle furnace at 280°C; Step 5, dissolving the sodium carbonate in water to obtain a porous body with a silver nanowire structure; Step 6, treating the surface of the porous body with a laser to cause in-situ pyrolysis of the polyvinylpyrrolidone coating the silver on the surface of the silver nanowires, obtaining a superhydrophobic layer containing nano-carbon materials. The solar-driven interface evaporator prepared by the above method has a strength of 3.2 MPa, a porosity of 82%, a pore size of 100 nm, and a contact angle of 153.7 degrees between the surface solar absorption layer and water.

[0017] Example 4:

[0018] A solar-driven interface evaporator: The solar-driven interface evaporator of this application comprises a porous body with a silver nanowire structure and a superhydrophobic silver nanowire and nano-carbon composite layer firmly bonded to the surface of the porous body, serving as a solar energy absorption layer. The preparation method of this evaporator includes the following steps: Step 1, centrifuging and concentrating a silver nanowire ethylene glycol dispersion prepared by a polyol method, and adjusting the concentration to 9 wt%; Step 2, adding sodium carbonate powder with a particle size of 50 nm to the centrifuged ethylene glycol silver nanowire concentrate and mixing thoroughly, the amount of sodium carbonate added being 0.8 times the silver content; Step 3, pressing the mixed sample into tablets using a tablet press at a pressure of 9 MPa; Step 4, sintering the tableted sample in muffle furnace at 300°C; Step 5, dissolving the sodium carbonate in water to obtain a porous body with a silver nanowire structure; Step 6, treating the surface of the porous body with a laser to cause in-situ pyrolysis of the polyvinylpyrrolidone coating the silver on the surface of the silver nanowires, obtaining a superhydrophobic layer containing nano-carbon materials. The solar-driven interface evaporator prepared by the above method has a strength of 3.7 MPa, a porosity of 85%, a pore size of 50 nm, and a contact angle of 155.7 degrees between the surface solar absorption layer and water.

[0019] Example 5:

[0020] A solar-driven interface evaporator: The solar-driven interface evaporator of this application comprises a porous body with a silver nanowire structure and a superhydrophobic silver nanowire and nano-carbon composite layer firmly bonded to the surface of the porous body, serving as a solar energy absorption layer. The preparation method of this evaporator includes the following steps: Step 1, centrifuging and concentrating a silver nanowire ethylene glycol dispersion prepared by the polyol method, and adjusting the concentration to 10 wt%; Step 2, adding sodium carbonate powder with a particle size of 10 nm to the centrifuged ethylene glycol silver nanowire concentrate and mixing thoroughly, the amount of sodium carbonate added being 0.5 times the silver content; Step 3, pressing the mixed sample into tablets using a tablet press at a pressure of 20 MPa; Step 4, sintering the tableted sample in muffle furnace at 330°C; Step 5, dissolving the sodium carbonate in water to obtain a porous body with a silver nanowire structure; Step 6, treating the surface of the porous body with a laser to cause in-situ pyrolysis of the polyvinylpyrrolidone coating the silver on the surface of the silver nanowires, obtaining a superhydrophobic layer containing nano-carbon materials. The solar-driven interface evaporator prepared by the above method has a strength of 5.8 MPa, a porosity of 81%, a pore size of 10 nm, and a contact angle of 156.7 degrees between the surface solar absorption layer and water.

Claims

1. A method for preparing a solar-driven interfacial evaporator, characterized in that: include: The solar-driven interface evaporator comprises a porous body with fibrous pores structured by silver nanowires and a superhydrophobic silver nanowire and nano-carbon composite layer obtained by laser pyrolysis of polyvinylpyrrolidone coated on the surface of silver nanowires. The method for preparing the solar-driven interface evaporator includes the following steps: Step 1: Centrifuge and concentrate the ethylene glycol dispersion of silver nanowires prepared by the polyol method, and adjust the concentration to 1wt% to 10wt%. Step 2: Add sodium carbonate powder with a particle size of 10 nm to 1 μm to the above-mentioned centrifuged ethylene glycol silver nanowire concentrate and mix well. The amount of sodium carbonate powder added is 0.5 to 2 times the silver content. Step 3: Compress the mixed sample into tablets using a tablet press at a pressure of 5–20 MPa. Step 4: Place the compressed sample in a muffle furnace and sinter at 240℃~330℃; Step 5: Place the sintered sample in water to dissolve the sodium carbonate and obtain a porous body with a silver nanowire structure. Step 6: The porous surface is treated with a laser to cause the polyvinylpyrrolidone coated on the surface of the silver nanowires to be pyrolyzed in situ to obtain a superhydrophobic layer containing nano-carbon materials.

2. The method of claim 1, wherein: The solar-driven interface evaporator has a strength of 2–5.8 MPa, a porosity of 81%–92%, a pore size of 10 nm–1 μm, and a contact angle between the surface solar absorption layer and water of 152.9°–156.7°.

3. The method of claim 1, wherein: The silver nanowires prepared by the polyol method have a thin coating of polyvinylpyrrolidone as a dispersant on their surface.

4. The method of claim 1, wherein: The prepared solar-driven interface evaporator is used for seawater desalination.

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