Carbon fiber-based solar photothermal conversion material as well as preparation method and application thereof

Abstract

The invention discloses a carbon fiber-based solar photo-thermal conversion material as well as a preparation method and application thereof, relates to the technical field of solar photo-thermal conversion materials, and solves the problems of poor mechanical performance and photo-thermal conversion performance of an existing photo-thermal conversion material. The preparation method comprises the following steps: thermally mixing a polyvinyl alcohol sodium alginate mixed solution, a graphene oxide solution and a cross-linking agent aqueous solution to prepare a cross-linking precursor solution; the preparation method comprises the following steps: by taking a carbon felt as a substrate, injecting a crosslinking precursor solution into the substrate by utilizing a vacuum infusion process, infiltrating the carbon felt, performing aging crosslinking, and then performing directional freeze drying to obtain a modified carbon felt; preparing an electroplating solution by using copper sulfate, sodium potassium tartrate tetrahydrate, disodium hydrogen phosphate and formaldehyde, adjusting the pH value by using NaOH, growing copper on the surface of the modified carbon felt by using an electroplating process, and carrying out vacuum drying; and putting the modified carbon felt subjected to vacuum drying after electroplating into a tubular furnace to obtain the carbon fiber-based solar photothermal conversion material. The method has a wide application prospect in the field of seawater evaporation desalination.

Description

Technical Field

[0001] The present invention relates to the technical field of solar photothermal conversion materials, and particularly relates to a carbon fiber-based solar photothermal conversion material, a preparation method thereof, and an application thereof. Background Art

[0002] With the increasingly severe problem of global freshwater shortage, seawater desalination has become one of the key ways to solve the water resource crisis. The solar-driven interfacial evaporation seawater desalination technology has emerged as the times require. Traditional seawater desalination methods such as distillation method and reverse osmosis method have limitations such as high energy consumption and complex equipment. Photothermal materials have unique advantages. They can efficiently absorb solar energy and convert it into heat energy, enabling seawater to quickly heat up and evaporate. This seawater desalination technology based on photothermal materials does not require an additional complex energy supply system and can utilize solar energy to drive the seawater evaporation and condensation process in areas with sufficient sunlight, thereby obtaining fresh water at low cost and high efficiency, and has great application potential and research value.

[0003] In the research of solar-driven water evaporation seawater desalination, the optimization of photothermal conversion technology is particularly crucial. Many researchers have successfully developed a variety of photothermal conversion materials that exhibit excellent solar absorption rates, which has significantly improved the photothermal conversion efficiency, and some achievements have exceeded the high conversion rate of 90%. Therefore, it is of great practical significance to accurately screen suitable photothermal conversion materials to enhance light absorption and further improve the photothermal conversion efficiency.

[0004] At present, the mainstream photothermal conversion materials mainly include carbon materials, semiconductor materials, metal-organic frameworks, etc. Among them, carbon materials have become the top choice for photothermal conversion materials due to their diverse available forms, high specific surface area, and excellent light absorption performance. As a high-quality material, graphene oxide has a large number of conjugated π bonds in its structure. These π bonds can interact with photons, resulting in a relatively high light absorption rate of graphene oxide and showing good light absorption in a wide solar spectrum range, and can absorb ultraviolet light, visible light, and near-infrared light. The photogenerated carriers generated under light can migrate quickly, which is beneficial to the conversion and utilization of light energy. The surface is rich in a large number of hydrophilic groups, which is easy to construct hydrophilic channels for transporting water, and at the same time has good thermal conductivity and chemical stability. It is suitable for preparing photothermal conversion materials. However, when facing the actual seawater desalination problem, the performance of a single photothermal material is not satisfactory.

[0005] Copper oxide (CuO), as a semiconductor material, has a certain light absorption ability in the visible and near-infrared regions. At the same time, electron-hole pairs are generated under light illumination. Combining copper oxide with reduced graphene oxide enables the electrons generated by copper to quickly transfer to the reduced graphene oxide, which can extend the lifetime of carriers, further improve the separation efficiency of photo-generated carriers, and enhance the photothermal effect. In addition, its nanostructure can produce a surface plasmon resonance effect to a certain extent, which synergistically interacts with the surface plasmon resonance effect of reduced graphene oxide, jointly enhancing the light absorption and light energy conversion ability of the composite material and improving the photothermal effect. Aerogels, due to their lightweight and porous structure, are convenient for constructing channels for water transport and steam escape. However, problems such as poor mechanical properties and durability are common during the actual preparation process, and agglomeration and fragmentation problems often occur, and sponges or other materials are required as carriers.

[0006] Therefore, the current urgent problem to be solved lies in how to enhance the mechanical properties, photothermal conversion performance, and practicality of photothermal conversion materials. In addition, due to the limitation of the photothermal conversion efficiency, traditional two-dimensional photothermal materials no longer meet the current performance requirements. Summary of the Invention

[0007] In order to solve the problems of poor mechanical properties and photothermal conversion performance of existing photothermal conversion materials, the present invention proposes a carbon fiber-based solar photothermal conversion material, its preparation method, and application.

[0008] The technical solution of the present invention is as follows:

[0009] A preparation method of a carbon fiber-based solar photothermal conversion material includes the following steps:

[0010] S1. Prepare a cross-linked precursor solution by thermally mixing a polyvinyl alcohol sodium alginate mixed solution, a graphene oxide solution, and an aqueous cross-linking agent solution;

[0011] S2. Using a carbon felt as a substrate, and by means of a vacuum infusion process, inject the cross-linked precursor solution into the substrate. After infiltrating the carbon felt, carry out aging cross-linking, and then perform directional freeze-drying to obtain a modified carbon felt;

[0012] S3. Prepare an electroplating solution with copper sulfate, sodium potassium tartrate, disodium hydrogen phosphate, and formaldehyde, and adjust the pH to 11-13 with NaOH. Use the electroplating process to grow copper on the surface of the modified carbon felt, and then perform vacuum drying;

[0013] S4. Place the modified carbon felt after electroplating and vacuum drying into a tubular furnace for carbonization treatment, and at the same time reduce graphene oxide to reduced graphene oxide to obtain a carbon fiber-based solar photothermal conversion material.

[0014] Preferably, the cross-linking agent is one of boric acid, glutaraldehyde, calcium chloride, or a mixture of two of them;

[0015] In the polyvinyl alcohol sodium alginate mixed solution, the mass fraction of polyvinyl alcohol is 2-5%, the mass fraction of sodium alginate is 0.5-2%, the concentration of the graphene oxide solution is 0.01 mg / L - 5 g / L, the mass fraction of glutaraldehyde is 0.3-0.5%, the mass fraction of calcium chloride is 0.2-0.5%, and the mass fraction of boric acid is 0.2-0.5%. The volume ratio of the graphene oxide solution to the polyvinyl alcohol sodium alginate mixed solution is 1:(1-6), and the ratio of the total volume of the polyvinyl alcohol sodium alginate mixed solution and the graphene oxide solution to the volume of the crosslinking agent aqueous solution is (1-6):1.

[0016] Preferably, the carbon felt is one or a mixture of at least two of recycled carbon fiber needle-punched fabric, chopped fibers, organic fiber carbide, and plant fiber carbide; the carbonization temperature of the organic fiber carbide and the plant fiber carbide is increased from room temperature to 600-800 °C at a rate of 5-10 °C / min and held for 1 h-3 h; the thickness of the carbon felt is 2-10 mm.

[0017] Preferably, the crosslinking temperature is 45 °C-60 °C, the crosslinking time is 10 min-5 h, and the freeze-drying time is 24 h-50 h.

[0018] Preferably, the concentrations of copper sulfate, potassium sodium tartrate, disodium hydrogen phosphate, and formaldehyde in the electroplating solution are 15-30 g / L, 10-15 g / L, 15-30 g / L, and 3-8 mL / L respectively; the electroplating voltage is 3-6 V, and the electroplating time is 2-5 min.

[0019] Preferably, the temperature of the vacuum drying is 40-100 °C, and the drying time is 10-24 h.

[0020] Preferably, the atmosphere of the carbonization treatment is nitrogen, and the temperature is increased from room temperature to 250-400 °C at a rate of 3-5 °C / min and held for 1-2 h.

[0021] The present invention also provides a carbon fiber-based solar thermal conversion material prepared by using the preparation method as described above.

[0022] The present invention also provides an interfacial evaporation device comprising the above-mentioned carbon fiber-based solar thermal conversion material.

[0023] The present invention also provides an application of the above interfacial evaporation device in the field of seawater evaporation and desalination.

[0024] Compared with the prior art, the specific beneficial effects of the present invention are:

[0025] The present invention successfully develops efficient solar thermal conversion materials through innovative three-dimensional structural design and material synergy. A self-floating skeleton structure is constructed with low-density, low-surface energy, high-strength, high-surface area, and carbon fiber felt with good light absorption as the base, which can attach more active materials. Not only has it broken through the performance limitations of traditional two-dimensional materials, its unique porous mesh structure gives the material excellent mechanical properties, while carbon fiber is also a carbon material with good light absorption. And by compounding with hydrophilic materials such as polyvinyl alcohol and sodium alginate, a through water molecule transmission channel and steam escape path are formed, which is beneficial to light capture and water transport, and increases the evaporation of water vapor. The constructed self-floating structure allows the prepared photothermal material to spontaneously float on the surface of seawater to form an evaporation interface while achieving a high solar light absorption rate, which is convenient for light absorption and conversion, and can continuously generate steam through surface irradiation without auxiliary devices, and obtain fresh water after condensation.

[0026] The three-dimensional structure constructed by the present invention cleverly integrates the dual photothermal advantages of graphene oxide and copper oxide. Graphene oxide relies on its wide spectrum absorption characteristics (covering ultraviolet to near-infrared bands) and abundant hydrophilic groups, and the photogenerated carriers generated under illumination can migrate quickly, which is beneficial to the conversion and utilization of light energy, and not only realizes the broad spectrum capture of solar energy, but also builds an efficient water transmission network. Copper oxide forms a synergistic effect with reduced graphene oxide through the surface plasmon resonance effect, significantly improving the carrier migration rate and further enhancing the photothermal conversion efficiency. At the same time, copper oxide, a semiconductor material, is used as a photothermal material, which cooperates with reduced graphene oxide to enhance carrier transmission and synergy, and at the same time, reduced graphene oxide and copper oxide cooperate with the surface plasmon resonance effect, thereby improving the photothermal effect. Efficient absorption and conversion of sunlight is achieved.

[0027] The solar thermal conversion material of the present invention can be placed in an interface evaporation device without any auxiliary floating equipment. Steam is generated when the surface is irradiated, and condensed water is collected after the steam is condensed. The operation of purifying water is simple, there is no environmental pressure, the photothermal conversion effect is excellent, and seawater desalination can be carried out continuously. The present invention has shown significant advantages in the fields of seawater desalination, industrial wastewater treatment, etc., and provides an innovative solution for sustainable water treatment technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a SEM image of the morphology of the modified carbon felt in Example 1 of the present invention;

[0029] Figure 2 This is a SEM image of the morphology of the modified carbon felt in Example 1 of the present invention;

[0030] Figure 3 This is a SEM image of the morphology of the modified carbon felt after copper plating in Example 1 of the present invention;

[0031] Figure 4 SEM image of the morphology of the carbon fiber-based solar thermal efficient conversion material prepared in Example 1 of the present invention;

[0032] Figure 5 XRD patterns of the modified carbon felt after copper plating and the carbon fiber-based solar thermal efficient conversion material in Example 1 of the present invention;

[0033] Figure 6 Photothermal rate diagram under one-fold sunlight irradiation when the carbon fiber-based solar thermal efficient conversion material prepared in Example 1 of the present invention is applied to photothermal conversion;

[0034] Figure 7 Comparison diagram of stress-strain curves with and without carbon fiber substrate between Example 1 and Comparative Example 1 of the present invention. Detailed implementation manners

[0035] To make the technical solutions of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention. It should be noted that the following embodiments are only used to better understand the technical solutions of the present invention and should not be construed as a limitation of the present invention.

[0036] Example 1.

[0037] The preparation method of the high-performance carbon fiber-based solar thermal conversion material with a three-dimensional structure in this embodiment is carried out according to the following steps:

[0038] (1) Preparation of carbon felt:

[0039] Use a high-speed needle punching machine roller needle to make the collected broken waste carbon fibers into a carbon felt, control the specifications, and cut it into a carbon felt sheet with a size of 10 cm × 10 cm and a thickness of 4 mm. Then soak it in deionized water for 30 minutes to remove surface impurities, and obtain a carbon fiber carbon felt, abbreviated as CF.

[0040] (2) Preparation of crosslinked precursor solution:

[0041] First, dissolve 2 g of sodium alginate powder and 5 g of polyvinyl alcohol particles in 300 mL of water, and mechanically stir in an oil bath at 85 °C until the sodium alginate and polyvinyl alcohol are completely dissolved to obtain a polyvinyl alcohol sodium alginate mixed solution.

[0042] Then mix the graphene oxide solution and the polyvinyl alcohol sodium alginate mixed solution evenly according to a volume ratio of 5:1 to obtain a polyvinyl alcohol sodium alginate graphene oxide mixed solution.

[0043] Next, dissolve 0.3 g of calcium chloride and 0.2 g of glutaraldehyde in 100 mL of hot water (60 °C) to obtain a calcium chloride glutaraldehyde mixed solution.

[0044] Finally, the polyvinyl alcohol sodium alginate graphene oxide mixed solution and the calcium chloride glutaraldehyde mixed solution were mixed at a volume ratio of 5:1 at a temperature of 45° C. and a stirring rate of 600 rpm for 10 minutes to obtain a cross-linked precursor solution.

[0045] (3) Preparation of modified carbon felt:

[0046] The carbon fiber felt prepared in step (1) is laid on the mold as a substrate. After vacuuming, the cross-linking precursor solution is introduced into the carbon felt through a plastic hose. The solution flows through the entire carbon felt under vacuum. After complete infiltration, the solution is aged and cross-linked at 45°C for 10 hours, then pre-frozen at -15°C for 24 hours, and then placed in a freeze dryer for freeze drying for 30 hours to obtain a modified carbon felt, referred to as CF / PVA / SA / GO.

[0047] The scanning electron microscopy image of the modified carbon felt is as follows: Figure 1 , Figure 2 As shown. Figure 1 It can be seen that polyvinyl alcohol and sodium alginate are firmly coated on the surface of carbon fiber and form a pore structure that penetrates each other with the carbon fiber. These pores provide multi-level diffuse reflection for the incident light, and the carbon fiber with excellent mechanical properties can improve the mechanical properties of the material. Figure 2 It can be seen that graphene oxide is evenly dispersed on the surface of carbon fiber. As one of the photothermal materials, the excellent photothermal response characteristics of graphene oxide can improve the photothermal effect of the material.

[0048] (4) Copper plating on carbon felt surface:

[0049] First, at room temperature, 8g copper sulfate, 8g disodium hydrogen phosphate, 7g potassium sodium tartrate, and 2.5mL formaldehyde (50%) were dissolved in 500mL water, ultrasonically stirred until completely dissolved, and the pH was adjusted to 12 with NaOH solution to obtain an electroplating solution. Then, the modified carbon felt prepared in (3) was placed in the electroplating solution, the electroplating machine wire was connected, the electroplating voltage was adjusted to 5V, and the electroplating time was adjusted to 300s. Then, the modified carbon felt after electroplating was taken out and dried under vacuum conditions to obtain copper-plated modified carbon felt, referred to as CF / PVA / SA / GO / Cu.

[0050] The scanning electron microscope image of the modified carbon felt after copper plating is as follows: Figure 3 As shown in the figure, it can be seen that copper is evenly deposited on the surface of carbon fiber.

[0051] (5) One-step method for reducing graphene oxide and copper oxide:

[0052] The copper-plated modified carbon felt obtained in (4) is placed in a tubular furnace with a carbonization atmosphere of nitrogen. Set the heating program: from room temperature to 350°C at a rate of 5°C / min. Set the insulation time to 1h, and keep nitrogen flowing during the insulation period. After the carbonization is completed, turn off the heating device, wait for the tubular furnace to cool naturally to room temperature, and turn off the nitrogen. Take out the sample to obtain a carbon fiber-based solar thermal conversion material, referred to as CF / PVA / SA / rGO / CuO.

[0053] Scanning electron microscope image of carbon fiber-based solar thermal conversion material Figure 4 As shown, copper oxide is uniformly coated on the surface of the carbon fiber. At the same time, XRD analysis was performed on the carbon fiber-based solar thermal conversion material and the copper-plated modified carbon felt in (4), and the obtained spectrum is as follows Figure 5 As shown in the figure, it can be seen that after carbonization, basic copper carbonate and copper element almost disappear, while two common crystal forms of copper oxide appear, proving the formation of copper oxide.

[0054] Use a xenon lamp that simulates sunlight, and irradiate at one times the sunlight for 1 hour. Control the distance from the liquid surface to the light probe to be 15 cm. Record the weight every 10 minutes and calculate the evaporation rate. Figure 6 As shown, the calculated evaporation rate is 2.01 Kg·m -2 ·h -1 .

[0055] Example 2.

[0056] The preparation method of the high-performance carbon fiber-based solar thermal conversion material with a three-dimensional structure in this embodiment is carried out according to the following steps:

[0057] (1) Preparation of carbon felt:

[0058] The collected broken waste carbon fibers were made into carbon felt using a high-speed needle loom roller needle, and the specifications were controlled and cut into carbon felt sheets with a size of 10 cm × 10 cm and a thickness of 4 mm. Then the sheets were soaked in deionized water for 30 minutes to remove surface impurities and obtain carbon felt.

[0059] (2) Preparation of cross-linking precursor solution:

[0060] First, 2 g of sodium alginate powder and 6 g of polyvinyl alcohol particles were dissolved in 300 mL of water, and mechanically stirred in an oil bath at 85° C. until the sodium alginate and polyvinyl alcohol were completely dissolved to obtain a polyvinyl alcohol sodium alginate mixed solution.

[0061] Then the graphene oxide solution and the polyvinyl alcohol sodium alginate mixed solution were evenly mixed in a volume ratio of 4:1.

[0062] Next, 0.25 g of calcium chloride and 0.2 g of glutaraldehyde were dissolved in 100 mL of hot water (60 °C) to obtain a calcium chloride - glutaraldehyde mixed solution.

[0063] Finally, the polyvinyl alcohol - sodium alginate - graphene oxide mixed solution and the calcium chloride - glutaraldehyde mixed solution were mixed at a volume ratio of 5:1 under the conditions of a temperature of 45 °C and a stirring rate of 600 rpm for 10 min to obtain a cross - linked precursor solution.

[0064] (3) Preparation of modified carbon felt:

[0065] The carbon fiber felt prepared in step (1) was laid on a mold as a substrate. After evacuating the air, the cross - linked precursor solution was introduced into the carbon felt through a plastic hose. It flowed through the entire carbon felt under vacuum and was completely infiltrated. After aging and cross - linking at 45 °C for 10 h, it was then pre - frozen at - 15 °C for 24 h, and then placed in a freeze - dryer and freeze - dried for 48 h to obtain the modified carbon felt.

[0066] (4) Preparation of elemental copper:

[0067] First, at room temperature, 9 g of copper sulfate, 9 g of disodium hydrogen phosphate, 7 g of potassium sodium tartrate, and 2.5 mL of formaldehyde (50%) were dissolved in 500 mL of water. After ultrasonic stirring until completely dissolved, the pH was adjusted to 13 using NaOH solution to obtain an electroplating solution. Then, the modified carbon felt prepared in (3) was placed in the electroplating solution, the wire of the electroplating machine was connected, the electroplating voltage was adjusted to 4 V, and the electroplating time was 300 s. Then, the electroplated modified carbon felt was taken out and dried under vacuum conditions to obtain the copper - plated modified carbon felt.

[0068] (5) One - step method for preparing reduced graphene oxide and copper oxide:

[0069] The copper - plated modified carbon felt prepared in (4) was placed in a tubular furnace, and the carbonization atmosphere was nitrogen. The heating program was set as follows: heating from room temperature to 300 °C at a rate of 5 °C / min. The holding time was set to 1 h, and nitrogen was kept flowing during the holding period. After carbonization was completed, the heating device was turned off, and the tubular furnace was allowed to cool naturally to room temperature, and then the nitrogen was turned off. The sample was taken out to obtain the carbon fiber - based solar thermal conversion material.

[0070] Example 3.

[0071] The preparation method of the high - performance carbon fiber - based solar thermal conversion material with a three - dimensional structure in this example was carried out according to the following steps:

[0072] (1) Preparation of carbon felt:

[0073] Use the roller needles of a high-speed needle punching machine to make the collected broken waste carbon fibers into carbon felt, control the specifications, cut it into carbon felt pieces with a size of 10 cm × 10 cm and a thickness of 4 mm. Then soak it in deionized water for 30 min to remove surface impurities, and obtain carbon felt.

[0074] (2) Prepare the cross-linked precursor solution:

[0075] First, dissolve 3 g of sodium alginate powder and 5 g of polyvinyl alcohol particles in 300 mL of water. In an oil bath at 85 °C, mechanically stir until sodium alginate and polyvinyl alcohol are completely dissolved to obtain a polyvinyl alcohol-sodium alginate mixed solution.

[0076] Then mix the graphene oxide solution and the polyvinyl alcohol-sodium alginate mixed solution evenly according to a volume ratio of 5:1.

[0077] Next, dissolve 2 mL of glutaraldehyde in 100 mL of hot water (60 °C) to obtain a glutaraldehyde solution.

[0078] Finally, mix the polyvinyl alcohol-sodium alginate-graphene oxide mixed solution and the glutaraldehyde solution according to a volume ratio of 5:1, and mix them at a temperature of 45 °C and a stirring rate of 600 rpm for 10 min to obtain the cross-linked precursor solution.

[0079] (3) Prepare the modified carbon felt:

[0080] Lay the carbon fiber felt prepared in step (1) on the mold as the substrate. After evacuating, introduce the cross-linked precursor solution into the carbon felt through a plastic hose. Under vacuum, it flows through the whole carbon felt. After complete infiltration, age and cross-link at 45 °C for 10 h, then pre-freeze at -15 °C for 24 h, and then place it in a freeze dryer and freeze-dry for 32 h to obtain the modified carbon felt.

[0081] (4) Prepare elemental copper:

[0082] First, at room temperature, dissolve 10 g of copper sulfate, 9 g of disodium hydrogen phosphate, 7 g of potassium sodium tartrate, and 2.5 mL of formaldehyde (50%) in 500 mL of water. Ultrasonically stir until completely dissolved, and use NaOH solution to adjust the pH to 12 to obtain the electroplating solution. Then place the modified carbon felt prepared in (3) in the electroplating solution, connect the wire of the electroplating machine, adjust the electroplating voltage to 4 V, and the electroplating time to 240 s.

[0083] Next, take out the electroplated modified carbon felt and dry it under vacuum conditions to obtain the copper-plated modified carbon felt.

[0084] (5) One-step method for reducing graphene oxide and copper oxide:

[0085] The copper-plated modified carbon felt prepared in (4) was placed in a tube furnace, and the carbonization atmosphere was nitrogen. Set the heating program: raise the temperature from room temperature to 300 °C at a rate of 5 °C / min. Set the holding time to 1 h, and keep the nitrogen flowing during the holding period. After the carbonization is completed, turn off the heating device, wait for the tube furnace to cool naturally to room temperature, and then turn off the nitrogen. Take out the sample to obtain a carbon fiber-based solar photothermal conversion material.

[0086] Example 4.

[0087] The preparation method of the high-performance carbon fiber-based solar photothermal conversion material with a three-dimensional structure in this example is carried out according to the following steps:

[0088] (1) Preparation of carbon felt:

[0089] Put the organic fiber into a tube furnace, and the carbonization atmosphere is nitrogen. Set the heating program: raise the temperature from room temperature to 800 °C at a rate of 10 °C / min, set the holding time to 2 h, and keep the nitrogen flowing during the holding period. After the carbonization is completed, turn off the heating device, wait for the tube furnace to cool naturally to room temperature, and then turn off the nitrogen. Take out the sample to obtain an organic fiber carbide, and use a high-speed needle punching machine roller needle to punch the organic fiber carbide into a carbon felt. Control the specifications and cut it into a carbon felt sheet with a size of 10 cm × 10 cm and a thickness of 4 mm. Then soak it in deionized water for 30 min to remove surface impurities to obtain a carbon felt.

[0090] (2) Preparation of crosslinked precursor solution:

[0091] First, dissolve 3 g of sodium alginate powder and 5 g of polyvinyl alcohol particles in 300 mL of water, and mechanically stir in an oil bath at 85 °C until the sodium alginate and polyvinyl alcohol are completely dissolved to obtain a polyvinyl alcohol sodium alginate mixed solution.

[0092] Then mix the graphene oxide solution and the polyvinyl alcohol sodium alginate mixed solution evenly according to a volume ratio of 5:1. Next, dissolve 2 mL of glutaraldehyde in 100 mL of hot water (60 °C) to obtain a glutaraldehyde solution.

[0093] Finally, mix the polyvinyl alcohol sodium alginate graphene oxide solution and the glutaraldehyde solution according to a volume ratio of 5:1 at a temperature of 45 °C and a stirring rate of 600 rpm for 10 min to obtain a crosslinked precursor solution.

[0094] (3) Preparation of modified carbon felt:

[0095] Lay the carbon fiber felt prepared in step (1) on the mold as the substrate. After evacuating the air, introduce the crosslinking precursor solution into the carbon felt through a plastic hose. Let it flow through the entire carbon felt under vacuum and be completely infiltrated. After that, age and crosslink at 45 °C for 10 h, then pre-freeze at -15 °C for 24 h, and then place it in a freeze dryer and freeze-dry for 32 h to obtain the modified carbon felt.

[0096] (4) Prepare elemental copper:

[0097] First, at room temperature, dissolve 10 g of copper sulfate, 9 g of disodium hydrogen phosphate, 7 g of potassium sodium tartrate, and 2.5 mL of formaldehyde (50%) in 500 mL of water. Stir ultrasonically until completely dissolved, and adjust the pH to 12 using NaOH solution to obtain the electroplating solution. Then place the modified carbon felt prepared in (3) into the electroplating solution, connect the wire of the electroplating machine, adjust the electroplating voltage to 4 V, and the electroplating time to 240 s. Then take out the electroplated modified carbon felt and dry it under vacuum conditions to obtain the copper-plated modified carbon felt.

[0098] (5) One-step method for preparing reduced graphene oxide and copper oxide:

[0099] Place the copper-plated modified carbon felt prepared in (4) into a tubular furnace, and the carbonization atmosphere is nitrogen. Set the heating program: raise the temperature from room temperature to 300 °C at a rate of 5 °C / min. Set the holding time to 1 h. Keep the nitrogen flowing during the holding period. After the carbonization is completed, turn off the heating device, wait for the tubular furnace to cool naturally to room temperature, and then turn off the nitrogen. Take out the sample to obtain the carbon fiber-based solar photothermal conversion material.

[0100] Comparative Example 1.

[0101] The difference between this comparative example and Example 1 is that it does not contain carbon felt, that is, step (1) is omitted, and the polyvinyl alcohol sodium alginate graphene oxide aerogel (PVA / SA / GO) without carbon felt (CF) is directly obtained.

[0102] Conduct a tensile test on the obtained PVA / SA / GO and the CF / PVA / SA / GO obtained in step (3) of Example 1, and the results are as Figure 7 shown. It can be seen that introducing the carbon fiber blanket with high mechanical strength and toughness effectively enhances the mechanical strength of the aerogel, enabling it to withstand higher tensile forces.

[0103] As described above, only the preferred specific embodiments of the present invention are provided. These specific embodiments are all different implementation manners based on the overall concept of the present invention, and the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

[0104] Obviously, the above embodiments are merely examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. A preparation method of a carbon fiber-based solar photothermal conversion material, characterized in that, It includes the following steps: S1. A crosslinked precursor solution is prepared by thermally mixing a polyvinyl alcohol sodium alginate mixed solution, a graphene oxide solution, and an aqueous crosslinking agent solution; S2. Using a carbon felt as a substrate, through a vacuum infusion process, the crosslinked precursor solution is injected into the substrate. After infiltrating the carbon felt, aging crosslinking is carried out, and then directional freeze-drying is performed to obtain a modified carbon felt; S3. Prepare an electroplating solution with copper sulfate, sodium potassium tartrate, disodium hydrogen phosphate, and formaldehyde, and adjust the pH to 11 - 13 with NaOH. Use the electroplating process to grow copper on the surface of the modified carbon felt, and then perform vacuum drying; S4. Put the modified carbon felt after electroplating and vacuum drying into a tube furnace for carbonization treatment, and at the same time reduce graphene oxide to reduced graphene oxide to obtain a carbon fiber-based solar photothermal conversion material.

2. The preparation method of the carbon fiber-based solar thermal conversion material according to claim 1, characterized in that The crosslinking agent is one of boric acid, glutaraldehyde, calcium chloride, or a mixture of two of them; In the polyvinyl alcohol sodium alginate mixed solution, the mass fraction of polyvinyl alcohol is 2 - 5%, the mass fraction of sodium alginate is 0.5 - 2%, the concentration of the graphene oxide solution is 0.01 mg / L - 5 g / L, the mass fraction of glutaraldehyde is 0.3 - 0.5%, the mass fraction of calcium chloride is 0.2 - 0.5%, the mass fraction of boric acid is 0.2 - 0.5%. The volume ratio of the graphene oxide solution to the polyvinyl alcohol sodium alginate mixed solution is 1:(1 - 6), and the ratio of the total volume of the polyvinyl alcohol sodium alginate mixed solution and the graphene oxide solution to the volume of the aqueous crosslinking agent solution is (1 - 6):

1.

3. The preparation method of the carbon fiber-based solar thermal conversion material according to claim 1, characterized in that, The carbon felt is one of recycled carbon fiber needle-punched fabric, short cut fibers, organic fiber carbide, plant fiber carbide, or a mixture of at least two of them; The carbonization temperature of the organic fiber carbide and the plant fiber carbide is raised from room temperature to 600 - 800 °C at a rate of 5 - 10 °C / min and held for 1 h - 3 h; The thickness of the carbon felt is 2 - 10 mm.

4. The preparation method of the carbon fiber-based solar photothermal conversion material according to claim 1, wherein The crosslinking temperature is 45 °C - 60 °C, the crosslinking time is 10 min - 5 h, and the freeze-drying time is 24 h - 50 h.

5. The preparation method of the carbon fiber-based solar thermal conversion material according to claim 1, characterized in that, In the electroplating solution, the concentrations of copper sulfate, sodium potassium tartrate, disodium hydrogen phosphate, and formaldehyde are 15 - 30 g / L, 10 - 15 g / L, 15 - 30 g / L, and 3 - 8 mL / L respectively; The electroplating voltage is 3 - 6 V, and the electroplating time is 2 - 5 min.

6. The preparation method of the carbon fiber-based solar thermal conversion material according to claim 1, characterized in that, The temperature of the vacuum drying is 40 - 100 °C, and the drying time is 10 - 24 h.

7. The preparation method of the carbon fiber-based solar thermal conversion material according to claim 1, characterized in that, The atmosphere of the carbonization treatment is nitrogen, and the temperature is raised from room temperature to 250 - 400 °C at a rate of 3 - 5 °C / min and held for 1 - 2 h.

8. A carbon fiber-based solar photothermal conversion material, characterized in that, It is prepared by using the preparation method according to any one of claims 1 - 7.

9. An interfacial evaporation device, characterized in that, It contains the carbon fiber-based solar photothermal conversion material according to claim 8.

10. Application of an interfacial evaporation device according to claim 9 in the field of seawater evaporation and desalination.

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