Solar water evaporation light-heat conversion material, preparation method and application thereof

Abstract

The application relates to a solar water evaporation light-heat conversion material, a preparation method and application thereof, and the solar water evaporation light-heat conversion material comprises flower-shaped MoS2 and a porous carbon film; the flower-shaped MoS2 is uniformly dispersed on the surface and in the interior of the porous carbon film, the size is 200nm-1mu m, the flower-shaped MoS2 is composed of mutually-crossed nanosheets, and the mass percentage of the flower-shaped MoS2 in the light-heat conversion material is 8-50%. The preparation method is as follows: firstly, a carbon nanotube-doped PAN-based film is prepared by using a phase inversion method; the porous carbon film is obtained after pre-oxidation and carbonization; and then, the flower-shaped MoS2 is uniformly loaded on the surface and in the interior of the porous carbon film by using a hydrothermal method. The material designed in the application has the synergistic absorption conversion capacity of the porous carbon film and the MoS2 to sunlight, the efficiency of solar water evaporation is effectively improved, the porous carbon film has rich pores and can transport water and conduct heat; the flower-shaped MoS2 can increase internal reflection and light absorption of light and convert the light into heat energy to conduct to the film, so that the reflection loss of light on the surface of the film is reduced, and the utilization rate of light is improved.

Description

Technical Field

[0001] This invention belongs to the field of freshwater collection technology, specifically relating to a solar water evaporation photothermal conversion material, its preparation method, and its application. Background Technology

[0002] Industrial development and rapid population growth have exacerbated water pollution and freshwater shortages, highlighting the crucial strategic importance of freshwater resources for sustainable development. Traditional water treatment technologies largely rely on high energy consumption to produce clean water, resulting in high costs and environmental pollution. Given the global shortage of fossil fuels and environmental challenges, utilizing renewable energy for water treatment has become a future trend.

[0003] Solar energy is an inexhaustible and clean energy source, and based on this, solar-driven interfacial water evaporation technology has attracted widespread attention. Compared with traditional technologies, interfacial water evaporation technology uses interfacial heating, confining heat to the gas-liquid interface and heating only a portion of the water at the interface, thereby greatly improving heat utilization and water evaporation rate. Photothermal conversion materials are one of the key conditions for achieving efficient solar water evaporation. Photothermal conversion materials must possess high solar energy absorption and conversion capabilities across the entire solar spectrum to maximize the utilization of solar radiation energy. Therefore, the preparation of a highly efficient and stable solar water evaporation photothermal conversion material is particularly important. Summary of the Invention

[0004] The purpose of this invention is to provide a solar water evaporation photothermal conversion material, its preparation method, and its application. The photothermal conversion material is composed of flower-like MoS2 and a porous carbon film. The flower-like MoS2 is composed of intersecting nanosheets. The photothermal conversion material is prepared by phase inversion and hydrothermal methods. The synergistic absorption and conversion capabilities of the porous carbon film and flower-like MoS2 for sunlight effectively improve the efficiency of solar water evaporation. Furthermore, the structure has been optimized to improve the surface undulation, resulting in good light refraction and absorption, effectively reducing light reflection on the film surface and improving the efficiency of solar water evaporation.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A photothermal conversion material for solar water evaporation includes flower-shaped MoS2 and a porous carbon film; the flower-shaped MoS2 is uniformly dispersed on the surface and inside of the porous carbon film, the size of the flower-shaped MoS2 is 200nm-1μm, and it is composed of intersecting nanosheets, the mass percentage of the flower-shaped MoS2 in the photothermal conversion material is 8-50%.

[0007] The present invention discloses a method for preparing a solar thermal conversion material for water evaporation, which involves preparing a carbon nanotube-doped PAN-based film by phase inversion, obtaining a porous carbon film through pre-oxidation and carbonization; mixing ammonium molybdate and thiourea with water, and uniformly loading flower-shaped MoS2 onto the porous carbon film using a hydrothermal method.

[0008] The preparation method of the solar thermal conversion material for water evaporation specifically includes the following steps:

[0009] (1) Preparation of porous carbon membranes

[0010] Polyacrylonitrile, carbon nanotubes, and N,N-dimethylformamide were mixed and heated in an oil bath with stirring until a uniform, viscous black casting solution was formed. After the casting solution cooled to room temperature, it was coated onto a dry and clean glass plate using an automatic coating machine to form a liquid film. The glass plate was then quickly transferred to deionized water to form a carbon nanotube-doped PAN-based film based on the phase transformation principle. After soaking for 12-24 hours, the film was removed and air-dried, then transferred to a vacuum drying oven to remove any remaining moisture. The dried film was then transferred to a muffle furnace for pre-oxidation and carbonized in a tube furnace to obtain a porous carbon film—a CNT / C membrane.

[0011] (2) Preparation of MoS2-CNT / C membrane

[0012] Ammonium molybdate and thiourea were dissolved in deionized water at room temperature to obtain a colorless and uniform hydrothermal solution. The hydrothermal solution was poured into a polytetrafluoroethylene reaction vessel, and then a CNT / C membrane was placed in it. The reaction vessel was sealed and placed in a muffle furnace with a heating program set to carry out the hydrothermal reaction. After the temperature naturally cooled to room temperature, a MoS2-CNT / C membrane was obtained.

[0013] The polyacrylonitrile used in step (1) has a molecular weight of 150,000, the N,N-dimethylformamide solution is analytical grade, and the carbon nanotubes are CNT-305.

[0014] Step (1) The thickness of the liquid film is 150-300 μm.

[0015] In step (1), the oil bath stirring temperature is 60-80℃ and the time is 18-24h.

[0016] The heating rate in step (1) of the pre-oxidation process is 2℃ / min. -1 The pre-oxidation time is 1-3 hours, the pre-oxidation temperature is 120-320℃, and the cooling rate is 1-10℃ / min. -1 .

[0017] In step (1), the carbonization process is carried out in an inert gas atmosphere with a heating rate of 5°C / min. -1 Heat to 600-900℃ and hold for 0.5-3 hours.

[0018] Step (1) also includes cooling the pre-oxidized membrane naturally and then using a stamping machine to form the membrane into a circular shape.

[0019] In step (2), the amount of ammonium molybdate added to the hydrothermal solution is 0.4-0.9 mg / mL. -1 The dosage of thiourea added is 2-5 mg / mL. -1 .

[0020] In step (2), the hydrothermal reaction temperature is 180-200℃, and the reaction time is 12-24h; the heating rate of the muffle furnace is 2℃ / min. -1 .

[0021] The present invention also provides a solar water evaporator, wherein the photothermal conversion material or water evaporation material of the evaporator adopts the aforementioned solar water evaporation photothermal conversion material.

[0022] The beneficial effects of this invention are as follows: This invention provides a solar water evaporation photothermal conversion material. In this material, flower-shaped MoS2 is uniformly and efficiently loaded onto the surface and interior of a carbon nanotube-doped porous carbon film via a hydrothermal method, providing a new method for the design of photothermal conversion materials. This patent uses CNTs as a framework and carbon coating to form a network structure. The rich network pore structure of this carbon film can better transport water and conduct heat. The flower-shaped MoS2 covering the surface and interior of the carbon film can enhance the internal reflection and light absorption of sunlight in MoS2, converting it into heat energy conducted to the film, thereby strengthening water evaporation. The synergistic absorption and conversion capabilities of the porous carbon film and flower-shaped MoS2 effectively improve the efficiency of solar water evaporation, achieving a water evaporation efficiency of 2.4-2.6 kg m³. -2 h -1 The solar energy conversion efficiency (η) reaches 95%. In the field of solar water evaporation, MoS2 has been proven to be a material with high photothermal efficiency, but it requires a thermally conductive substrate to help it conduct heat and form an integral structure. Therefore, this invention designs a composite material of MoS2 supported by a network thermally conductive carbon film, and utilizes the synergistic effect between the two to improve the photothermal water evaporation efficiency.

[0023] This invention provides a method for preparing solar water evaporation photothermal conversion materials. This preparation method is simple, readily available, inexpensive, and environmentally friendly.

[0024] Figure 1 This is a scanning electron microscope image of the surface of the solar water evaporation photothermal conversion material prepared in Example 1.

[0025] Figure 2 This is a scanning electron microscope image of the cross-section of the solar water evaporation photothermal conversion material prepared in Example 1.

[0026] Figure 3The image shows the absorption spectrum of the surface of the photothermal evaporation material prepared by the method in Example 1.

[0027] Figure 4 For 1kW m -2 A comparison of the water evaporation rate of the solar water evaporation photothermal conversion material prepared by the method of Example 1 under (sunlight) intensity irradiation with pure water.

[0028] Figure 5 The image shows the cyclic stability test results of the photothermal evaporation material prepared by the method in Example 1.

[0029] Figure 6 1kW m -2 A comparison of the water evaporation rates of solar water evaporation photothermal conversion materials prepared using the methods in Examples 1, 2, 3, and 4 under (sunlight) intensity irradiation. Detailed Implementation Plan

[0030] The invention will be further illustrated below with examples, but is not limited thereto. Unless otherwise specified, all methods described are conventional methods. Unless otherwise specified, all raw materials or instruments can be obtained commercially.

[0031] Example 1

[0032] 1 g of polyacrylonitrile, 1 g of carbon nanotubes, and 12 g of N,N-dimethylformamide (DMF) were placed in a 50 mL thread-sealed reagent bottle and stirred in an oil bath at 60-80 °C for 12 h until a uniform, viscous black casting solution was formed. After the casting solution cooled to room temperature, it was coated onto a dry, clean glass plate using an automatic coating machine to form a liquid film with a thickness of 200 μm. The glass plate was then quickly transferred to deionized water to form a porous membrane-carbon nanotube-doped PAN-based membrane based on the phase inversion principle. After soaking for 24 h, the membrane was removed, air-dried, and then transferred to a vacuum drying oven at 90 °C for 4 h to remove any remaining moisture. The dried porous membrane was then transferred to a muffle furnace and dried at 2 °C for 1 min. -1 The temperature was increased to 250℃ at a certain heating rate and held for 2 hours. After the temperature naturally cooled to room temperature, the pre-oxidation treatment was completed. Then, the carbon film was formed into circular films with a diameter of 2 cm using a stamping machine. The circular films were placed in a tube furnace filled with argon gas and heated at 5℃ for 1 minute. -1 The temperature was increased to 700℃ at a controlled heating rate and held for 1 hour for carbonization treatment to obtain a porous carbon membrane—CNT / C membrane. 34 mg ammonium molybdate, 167 mg thiourea, and 60 mL water were mixed and magnetically stirred at room temperature for 30 min to obtain a colorless, homogeneous hydrothermal solution. This hydrothermal solution was poured into a polytetrafluoroethylene-lined reactor, and a CNT / C membrane was placed inside. The reactor was then tightened and placed in a muffle furnace at 2℃ for 1 minute. -1The temperature was increased to 200℃ at a certain rate and held for 24 hours. After the temperature dropped to room temperature, the reactor was removed to obtain the MoS2-CNT / C membrane.

[0033] Figure 1 and Figure 2 The image shows a scanning electron microscope image of the prepared MoS2-CNT / C film. It can be seen from the image that the particle size of MoS2 is relatively uniform and its distribution on the carbon film is relatively uniform. The individual MoS2 flower spheres are composed of intersecting nanosheets. The cross-section shows that there are also hydrothermal products inside the film.

[0034] Figure 3 The absorption spectrum of the prepared MoS2-CNT / C film for sunlight in the wavelength range of 250–2500 nm shows that the MoS2-CNT / C film has a strong absorption capacity for sunlight and is suitable for use as a photothermal conversion material.

[0035] Figure 4 The comparison between the water evaporation efficiency of the photothermal conversion material prepared using the method in Example 1 under irradiation with one times the solar intensity and that of pure water shows that the evaporation efficiency of the prepared photothermal conversion material is approximately seven times that of pure water. The water evaporation efficiency of the photothermal material prepared using the method in Example 1 is calculated to be 2.4-2.6 kg m³ after fitting the slope of the straight line. -2 h -1 .

[0036] Using the existing formula (1) for calculating solar energy conversion efficiency, the solar energy conversion efficiency (η) of the photothermal conversion material prepared by the above steps reaches 95%.

[0037]

[0038] In the formula, η represents the solar thermal conversion efficiency. ΔH represents the amount of water evaporated per unit time. equ C is the equivalent enthalpy of vaporization of water in a photothermal device. opt P0 is the optical concentration, and P0 is the radiant power of one solar radiation intensity.

[0039] Figure 5 To test the cyclic stability of the solar water evaporation photothermal conversion material prepared by the method in Example 1, the material still maintained a relatively stable evaporation rate after being reused 30 times, which shows that this photothermal conversion material has good cyclic stability.

[0040] Example 2

[0041] Same as Example 1, but without hydrothermal treatment of the porous carbon membrane. The porous carbon membrane was tested under one times the intensity of sunlight to obtain the relationship between water evaporation and light exposure time.

[0042] Example 3

[0043] Same as Example 1, but the mass of ammonium molybdate in the hydrothermal solution is 26 mg and the mass of thiourea is 125 mg. The obtained photothermal conversion material was tested under irradiation with one times the intensity of sunlight to obtain the relationship between water evaporation and irradiation time.

[0044] Example 4

[0045] Same as Example 1, but the mass of ammonium molybdate in the hydrothermal solution is 51 mg and the mass of thiourea is 250 mg. The obtained photothermal conversion material was tested under irradiation with one times the intensity of sunlight to obtain the relationship between water evaporation and irradiation time.

[0046] Figure 6 The graph shows the relationship between the evaporation rate and time of photothermal conversion materials with different MoS2 loadings under irradiation with one times the solar intensity. The comparison shows that as the MoS2 loading increases, the water evaporation rate first increases and then decreases.

[0047] The above examples are merely one specific implementation of the present invention. Although the descriptions are quite detailed, they should not be construed as limiting the scope of the present invention. It must be noted that any obvious substitutions, such as modifications and extensions, made by those skilled in the art without departing from the concept of the present invention are all within the scope of protection of the present invention.

Claims

1. A solar water evaporation photothermal conversion material, characterized in that: The material comprises flower-shaped MoS2 and a porous carbon film; the flower-shaped MoS2 is uniformly loaded on the surface and inside of the porous carbon film, the size of the flower-shaped MoS2 is 200 nm-1 μm, and it is composed of intersecting nanosheets; the mass percentage of the flower-shaped MoS2 in the photothermal conversion material is 8-50%. Used for solar water evaporation photothermal conversion; the preparation method of the solar water evaporation photothermal conversion material involves preparing a carbon nanotube-doped PAN-based film using a phase transformation method, obtaining a porous carbon film through pre-oxidation and carbonization; then mixing ammonium molybdate and thiourea with water, and uniformly loading flower-shaped MoS2 onto the porous carbon film using a hydrothermal method.

2. A method for preparing a solar water evaporation photothermal conversion material as described in claim 1, characterized in that: Specifically, the steps include the following: (1) Preparation of porous carbon membranes Polyacrylonitrile, carbon nanotubes, and N,N-dimethylformamide were mixed and heated in an oil bath with stirring until a uniform, viscous black casting solution was formed. After the casting solution cooled to room temperature, it was coated onto a dry and clean glass plate using an automatic coating machine to form a liquid film. The glass plate was then quickly transferred to deionized water to form a carbon nanotube-doped PAN-based film based on the phase inversion principle. After soaking for 12-24 hours, the film was removed and air-dried, then transferred to a vacuum drying oven to remove any remaining moisture. The dried film was then transferred to a muffle furnace for pre-oxidation and carbonized in a tube furnace to obtain a porous carbon film—CNT / C membrane. (2) Preparation of MoS2-CNT / C membrane Ammonium molybdate and thiourea were dissolved in deionized water at room temperature to obtain a colorless and uniform hydrothermal solution. The hydrothermal solution was poured into a polytetrafluoroethylene reaction vessel, and then a CNT / C membrane was placed in it. After sealing, the reaction vessel was placed in a muffle furnace and a heating program was set to carry out the hydrothermal reaction. After the temperature naturally cooled to room temperature, a MoS2-CNT / C membrane was obtained.

3. The method for preparing a solar water evaporation photothermal conversion material as described in claim 2, characterized in that: The polyacrylonitrile used in step (1) has a molecular weight of 150,000, the N,N-dimethylformamide solution is analytical grade, and the carbon nanotubes are CNT-305.

4. The method for preparing a solar water evaporation photothermal conversion material as described in claim 2, characterized in that: In step (1), the oil bath stirring temperature is 60-80℃ and the time is 18-24 h.

5. The method for preparing a solar water evaporation photothermal conversion material as described in claim 2, characterized in that: The heating rate in step (1) of the pre-oxidation process is 2℃ min. -1 The pre-oxidation time is 1-3 hours, the pre-oxidation temperature is 120-320℃, and the cooling rate is 1-10℃ / min. -1 .

6. The method for preparing a solar water evaporation photothermal conversion material as described in claim 2, characterized in that: In step (1), the carbonization time is 0.5-3 h and the carbonization temperature is 600-900℃.

7. A method for preparing a solar water evaporation photothermal conversion material as described in claim 2, characterized in that: In step (2), the amount of ammonium molybdate added to the hydrothermal solution is 0.4-0.9 mg / mL. -1 The dosage of thiourea added is 2-5 mg / mL. -1 .

8. A method for preparing a solar water evaporation photothermal conversion material as described in claim 2, characterized in that: In step (2), the hydrothermal temperature is 180-200℃ and the hydrothermal time is 12-24 h.

9. A solar water evaporator, characterized in that: The photothermal conversion material or water evaporation material of the evaporator is the solar water evaporation photothermal conversion material as described in claim 1.

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