Nano coating for self-cleaning polycrystalline solar module and preparation method

Abstract

The invention relates to the technical field of coating preparation, in particular to a nano coating for a self-cleaning polycrystalline solar module and a preparation method, and the coating is formed by compounding a titanium dioxide nanotube, fluorosilane modified silicon dioxide aerogel, graphene quantum dots and a polyaniline-polypyrrole copolymer; the preparation method comprises the following steps: preparing titanium dioxide nanotubes through hydrothermal reaction and calcination, synthesizing aerogel through a sol-gel method, performing pyrolysis reduction to prepare quantum dots, and performing oxidative polymerization to obtain a conductive polymer; all the components are dispersed in a solvent in proportion, ultrasonic dispersion is performed after a flatting agent is added, a solar module is coated with the mixture through a dip-coating method, and the coating is formed through drying and ultraviolet curing. According to the self-cleaning nano-coating, through multi-component compounding, a multi-stage coarse structure is formed, super-hydrophobicity is achieved, the light response range is widened, the photocatalytic efficiency is improved, the electrical property is improved, and the photoelectric conversion rate is increased.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coating preparation, in particular to a nano coating for self-cleaning multi-crystalline solar modules and a preparation method thereof. BACKGROUND

[0002] With the rapid development of the solar photovoltaic industry, the efficiency and durability of solar modules have become key technical bottlenecks. The surface of traditional solar modules is easily contaminated by dust, bird droppings, water stains and other pollutants, resulting in a decrease in light transmittance and a decrease in photoelectric conversion efficiency. Studies have shown that the power loss of untreated modules can reach more than 15% after 6 months of outdoor use. Existing solutions mostly use conventional titanium dioxide coatings, but such coatings have low photocatalytic efficiency and poor hydrophobicity, making it difficult to meet the long-term outdoor use requirements.

[0003] In the field of self-cleaning coatings, the introduction of nano structures provides a new direction for improving coating performance. However, the application of single nano materials (such as titanium dioxide nanoparticles) has limitations: the insufficient specific surface area results in limited photocatalytic active sites, and the high surface energy makes it difficult to achieve superhydrophobicity. In addition, existing technologies mostly focus on optimizing a single function, such as improving only photocatalytic performance or hydrophobicity, and lack solutions for synergistic improvement of multiple properties, making it difficult to effectively solve the dual problems of pollutant deposition and decreased light absorption efficiency.

[0004] For the preparation process of the coating, traditional methods such as sol-gel and spraying have poor coating uniformity and weak adhesion to the substrate. At the same time, although high-temperature calcination and chemical vapor deposition can improve the performance of the coating, they have high energy consumption, complex equipment and high cost, which limits their large-scale application. Therefore, developing a self-cleaning nano coating with efficient photocatalysis and superhydrophobicity, as well as a simple and controllable preparation process, has become a technical problem to be solved. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a nano coating for self-cleaning multi-crystalline solar modules and a preparation method thereof.

[0006] The purpose of the present application is achieved by the following technical solutions: A nano coating for self-cleaning multi-crystalline solar modules is made from the following raw materials by weight: titanium dioxide nanotubes 50-60 parts, fluorosilane modified silica aerogel 30-40 parts, graphene quantum dots 5-10 parts, and polyaniline-pyrrole copolymer 3-8 parts. The titanium dioxide nanotubes are prepared by a hydrothermal method, and the reaction formula is: ; ; The fluorosilane-modified silica aerogel was prepared by a hexadecyltrimethylammonium bromide template method, with a porosity of 85-95% and an average pore size of 15-25 nm. The nano-coating also incorporates carbon nano-angle-modified carbon nitride quantum dots, which have a mass of 5-10% of the titanium dioxide nanotubes. These are prepared by reacting 5,10,15,20-tetra(4-carboxyphenyl)porphyrin with melamine at 200-300 °C for 3 hours under a nitrogen atmosphere.

[0007] Preferably, the surface of the graphene quantum dots is modified by dopamine self-polymerization to form a polydopamine coating layer with a thickness of 5-10 nm, and the polydopamine layer is loaded with platinum nanoparticles with a particle size of 2-5 nm, the loading amount being 1-3% of the mass of the graphene quantum dots.

[0008] Preferably, the polyaniline-polypyrrole copolymer is prepared by microemulsion polymerization, using sodium dodecylbenzenesulfonate as emulsifier and ammonium persulfate as initiator, with a reaction temperature of 0-5°C and a reaction time of 12-16 hours, and 3-5% of 3,4-ethylenedioxythiophene units are introduced into the copolymer.

[0009] Preferably, in the preparation of the fluorosilane-modified silica aerogel, hollow glass microspheres accounting for 2-5% of the total mass of the silicon source are added. The hollow glass microspheres have a particle size of 10-30 μm, a wall thickness of 1-3 μm, and are filled with perfluorohexane.

[0010] Preferably, the inner wall of the titanium dioxide nanotube is loaded with cadmium sulfide quantum dots, which are prepared by ion exchange method. The particle size of the cadmium sulfide quantum dots is 3-8 nm, and the loading amount is 3-7% of the mass of the titanium dioxide nanotube.

[0011] Preferably, the surface of the nano-coating is formed into a micro-nano composite structure by laser etching. The microstructure consists of pits with a diameter of 10-20 μm and a spacing of 50-100 μm, while the nanostructure consists of protrusions with a height of 50-100 nm and a density of 10. 6 -10 7 pcs / cm²

[0012] Preferably, the method for preparing the nanocoating according to any one of the above-mentioned methods includes the following steps: S1. Preparation of titanium dioxide nanotubes: Titanium sheets were placed in a 10-15 mol / L NaOH solution and hydrothermally reacted at 150-180℃ for 24 hours. After washing, they were calcined at 450-550℃ for 2 hours, with 5-10% hydrogen gas by volume introduced during calcination. S2. Fluorosilane modified silica aerogel preparation: tetraethyl orthosilicate, methyltrimethoxysilane, 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane are mixed in a molar ratio of 3:1:1, hydrolyzed in a hydrochloric acid solution with a pH of 2-3, 1-3% of polyvinylpyrrolidone based on the total mass of the silicon source is added, solvent exchange and supercritical drying are performed, and calcination is performed at 600-700°C for 1 hour; S3. Graphene quantum dot synthesis: citric acid and urea are mixed in a mass ratio of 3:1, placed in a muffle furnace, pyrolyzed at 200-250°C for 30 minutes, dissolved in deionized water after cooling, and a chloroplatinic acid solution is added and reduced with sodium borohydride; S4. Preparation of polyaniline-pyrrole copolymer: aniline, pyrrole and 3,4-ethylenedioxythiophene are dissolved in a 0.5-1 mol / L hydrochloric acid solution in a molar ratio of 6:3:1, 1-2% of sodium dodecylbenzenesulfonate based on the total mass of the monomers is added, and ammonium persulfate initiator is added at 0-5°C, and the reaction is carried out for 12-16 hours; S5. Composite dispersion: the components are mixed in proportion, a mixed solvent of ethanol and deionized water is added, ultrasonic dispersion is carried out for 30-60 minutes, the ultrasonic frequency is 40-60 kHz, the power is 200-300 W, and a magnetic field of 0.5-1T is applied during dispersion; S6. Coating: the mixed solution is coated on the surface of the solar module by dip coating, the dip coating speed is 5-10 cm / min, the number of pulling is 2-3 times, and the coating is cured at 100-120°C for 1-2 hours, and ultraviolet light with a wavelength of 365 nm is irradiated during curing, and the light intensity is 5-10 mW / cm².

[0013] Preferably, the volume ratio of ethanol to deionized water in the mixed solvent in step S5 is 4:1, and 0.1-0.5% of polyether modified polydimethylsiloxane is added as a leveling agent based on the total mass of the mixed solution.

[0014] Preferably, the module after coating in step S6 is subjected to humidity treatment at 50-60°C for 24-48 hours, and the relative humidity is 70-80%.

[0015] Preferably, the aspect ratio of the titanium dioxide nanotubes prepared in step S1 is 50-100, and the fluorescence quantum yield of the graphene quantum dots prepared in step S3 is 30-40%.

[0016] Compared with the prior art, the beneficial effects of the present application are: 1.The self-cleaning nano coating provided by the present application effectively overcomes the defects of the prior art through multi-component synergistic design and innovative process. First, the composite of titanium dioxide nanotubes and fluorosilane modified silica aerogel builds a multi-level rough structure of "nanotube array-porous aerogel", greatly reduces the surface energy of the coating, makes the water contact angle reach more than 155°, and the water droplet rolling angle on the coating surface is less than 5°, realizing super-hydrophobic effect and significantly improving the anti-pollutant adhesion capacity. Experiments show that the amount of dust attached to the surface of the coating is reduced compared with traditional coatings, effectively reducing the frequency of cleaning and maintenance.

[0017] 2.The introduction of graphene quantum dots and carbon nanohorns widens the light response range of the coating. Traditional titanium dioxide only responds to ultraviolet light, while the coating of the present application expands the light absorption edge to the visible light region (420 nm) through the surface plasmon resonance effect of the quantum dots, greatly improving the photocatalytic efficiency. Under simulated sunlight irradiation, the degradation rate of organic pollutants such as methyl orange is higher than that of traditional coatings, which can quickly decompose surface organic matter and further enhance the self-cleaning ability.

[0018] 3.The addition of polyaniline-polyazole conductive polymer improves the electrical properties of the coating. The polymer forms a heterojunction with titanium dioxide, effectively promoting the separation and transport of photo-generated carriers, improving the photoelectric conversion efficiency of solar modules. At the same time, the coating preparation process uses ultrasonic dispersion and magnetic field assisted technology, without the need for high temperature and high pressure equipment, simplifying the process and reducing costs, suitable for large-scale industrial production. Overall, the coating of the present application realizes synergistic optimization in super-hydrophobicity, photocatalysis, and photoelectric conversion, providing an innovative solution for efficient and long-term application of solar modules. BRIEF DESCRIPTION OF DRAWINGS

[0019] Fig. 1 is a nano coating preparation flow chart for self-cleaning polycrystalline solar modules proposed by the present application; Fig. 2 is a column chart comparing the water contact angle and photocatalytic degradation rate of the examples and comparative examples; Fig. 3 is a line chart comparing the dust adhesion amount and rolling angle of the examples and comparative examples; Fig. 4 is a visible light catalytic aging fitting curve of the examples and comparative examples. DETAILED DESCRIPTION

[0020] According to Figs. 1 to 4 , the specific embodiments of the present application are as follows: Example 1: Preparation of standard self-cleaning nano coating Preparation of raw materials and instruments: Titanium sheets with purity of 99.5%, size of 5 cm x 5 cm x 0.5 mm were used as the substrate material, 12 mol / L sodium hydroxide solution was prepared for hydrothermal reaction, tetraethyl orthosilicate, methyltrimethoxysilane and 1H, 1H, 2H, 2H- perfluorooctyltriethoxysilane were used as the silicon source, citric acid and urea were used for preparing graphene quantum dots, aniline, pyrrole and 3,4- ethylenedioxythiophene were used as the conductive polymer monomer, chloroplatinic acid solution and sodium borohydride solution were used for platinum nanoparticle loading, and polyether modified polydimethylsiloxane was used as the leveling agent. The experimental equipment included a hydrothermal reactor with a polytetrafluoroethylene liner, a supercritical drying instrument, an ultrasonic dispersing instrument, a magnetic field generator and an ultraviolet curing box. S1. Preparation of titanium dioxide nanotubes: The titanium sheet was placed in a beaker containing acetone and cleaned with an ultrasonic cleaner with a power of 300 W for 15 minutes to remove surface oil stains, then rinsed with deionized water for 3 times, and dried in a vacuum drying oven at 80°C for 2 hours. The pretreated titanium sheet was vertically hung in a hydrothermal reactor containing 12 mol / L sodium hydroxide solution, sealed and placed in an oven at 160°C for 24 hours. After the reaction was completed, it was cooled to room temperature, immersed in 0.1 mol / L hydrochloric acid solution for 30 minutes for neutralization treatment, then washed with deionized water until the pH value was 7, and finally dried in a vacuum drying oven at 80°C for 12 hours. The dried titanium sheet was placed in a muffle furnace and calcined at 500°C for 2 hours while passing in 5% hydrogen gas (nitrogen dilution, flow rate 50 mL / min), obtaining a nanotube array with a mixed phase of anatase-rutile (7:3), a length of about 800 nm, an outer diameter of 12 nm and an inner diameter of 5 nm. S2. Preparation of fluorosilane modified silica aerogel: In a three-necked flask, 3 mol of tetraethyl orthosilicate, 1 mol of methyltrimethoxysilane and 1 mol of perfluorooctyltriethoxysilane were added, and after uniform stirring with a magnetic stirrer, 100 mL of hydrochloric acid solution with a pH value of 2.5 was slowly added dropwise, and hydrolysis was carried out in a constant temperature water bath at 60°C for 2 hours to form a transparent sol. 1.00 g of cetyltrimethylammonium bromide template was added, stirred for 30 minutes, then poured into a culture dish and gelled at room temperature for 24 hours. The gel was soaked in anhydrous ethanol for 3 times, each time for 24 hours, then transferred to a supercritical drying instrument and dried at 40°C and 7.38 MPa for 12 hours, finally ground and calcined in a muffle furnace at 650°C for 1 hour, obtaining an aerogel with a porosity of 90%, an average pore size of 20 nm and a hydrophobic angle of 155°.

[0021] S3. Synthesis of graphene quantum dots: Citric acid and urea were mixed in a mass ratio of 3:1 and placed in a ceramic crucible, and pyrolysis was carried out in a muffle furnace at 220°C for 30 minutes. After cooling, it was dissolved in 100 mL of deionized water and ultrasonically dispersed for 30 minutes to obtain a brownish yellow solution. Under ice bath conditions, 5.00 mL of chloroplatinic acid solution was added to the solution, followed by slow dropwise addition of 10.00 mL of sodium borohydride solution, with the temperature controlled to not exceed 5°C, and stirring for 1 hour. After the reaction was completed, centrifugation was performed at 10,000 rpm for 15 minutes, the precipitate was washed with deionized water 3 times, and freeze-drying was performed for 48 hours to obtain graphene quantum dots with a particle size of 10 nm, a platinum loading of 1.5%, and a quantum yield of 25%.

[0022] S4. Preparation of polyaniline-pyrrole copolymer: Aniline, pyrrole, and 3,4-ethylenedioxythiophene were dissolved in 200 mL of 1 mol / L hydrochloric acid solution in a molar ratio of 6:3:1, 2.00 g of sodium dodecylbenzenesulfonate emulsifier was added, and stirring was performed in an ice bath at 0°C for 30 minutes. 0.8 mol of ammonium persulfate initiator was slowly added, and dropwise addition was performed at 0°C for 1 hour, with the reaction temperature controlled to not exceed 5°C, and stirring was continued for 14 hours. After the reaction was completed, centrifugation was performed at 8000 rpm for 15 minutes, the precipitate was washed with deionized water and ethanol 3 times each, and drying was performed in a vacuum drying oven at 60°C for 12 hours to obtain a copolymer with a conductivity of 0.05 S / cm. S5. Composite dispersion: Nanotubes, aerogel, quantum dots, and copolymer were weighed in a weight ratio of 55:35:8:5, poured into a beaker, 500 mL of a mixed solvent of ethanol-deionized water (4:1) was added, and dispersion was performed using an ultrasonic disperser at 40 kHz and 250 W for 45 minutes, while a magnetic field of 0.8 T was applied (the direction was perpendicular to the ultrasonic propagation direction). Finally, 0.30 g of polyether-modified silicone was added, and magnetic stirring was performed for 10 minutes. Dynamic light scattering tests showed that the average particle size was 120 nm, and the distribution width was 0.15. S6. Coating application: After the polycrystalline solar module was wiped with ethanol 3 times, it was fixed on the dip coating device. The mixed solution was poured into the dip coating tank, and the module was immersed and pulled out twice at a speed of 8 cm / min. After standing at room temperature for 5 minutes, it was placed in a 110°C oven for 1.5 hours, and irradiated with a 365 nm ultraviolet lamp with a light intensity of 8 mW / cm² to obtain a coating with a thickness of 200 nm. Performance test data: The coating water contact angle is 158°±2° according to GB / T 30035-2013 standard, showing super-hydrophobic state; the photocatalytic degradation rate is 92.3% within 3 hours according to GB / T 23761-2009 standard, which is 40% higher than the conventional one; the photoelectric conversion efficiency is 8.5% higher than the uncoated component according to GB / T 18911-2015 standard, which is 3 times of the traditional coating. Example 2: Preparation of enhanced photocatalytic coating Raw materials and instruments preparation: Titanium sheets with purity of 99.5%, size of 5 cm x 5 cm x 0.5 mm were used as substrate material, 12 mol / L sodium hydroxide solution was prepared for hydrothermal reaction, tetraethyl orthosilicate, methyltrimethoxysilane and 1H,1H,2H,2H-perfluorooctyltriethoxysilane were used as silicon source, citric acid and urea were used for preparing graphene quantum dots, aniline, pyrrole and 3,4-ethylenedioxythiophene were used as conductive polymer monomers, chloroplatinic acid solution and sodium borohydride solution were used for platinum nanoparticle loading, polyether modified polydimethylsiloxane was used as leveling agent. Experimental equipment includes a hydrothermal reactor with a polytetrafluoroethylene liner, a supercritical drying instrument, an ultrasonic dispersing instrument, a magnetic field generator and a ultraviolet curing box, tetra(4-carboxyphenyl) porphyrin and melamine were added as raw materials for preparing carbon nanohorns CNQDs, a tube furnace and a high-resolution transmission electron microscope were used for preparation and characterization. S1. Preparation of CNQDs: Porphyrin and melamine were mixed in a mass ratio of 1:5 and placed in a quartz boat in a tube furnace, nitrogen gas was introduced at a flow rate of 100 mL / min, the temperature was raised to 250°C at a rate of 5°C / min and held for 3 hours. After cooling, the product was ground, washed with deionized water 3 times, 100 mL each time, then centrifuged at 8000 rpm for 10 minutes, and freeze-dried for 24 hours to obtain CNQDs with a particle size of 5 nm and a carbon nanohorn length of 20 nm. S2. Nanotube modification: The preparation steps of titanium dioxide nanotubes in Example 1 were repeated, but the hydrothermal reaction time was shortened to 20 hours, the calcination temperature was reduced to 480°C, and the hydrogen flow was increased to 80 mL / min (volume fraction 8%). The specific surface area of the prepared nanotubes was 280 m² / g, the aspect ratio was 60:1, and the light absorption edge was red-shifted to 420 nm. S3. Quantum dot compounding: The prepared CNQDs were added in a proportion of 8% of the mass of titanium dioxide nanotubes, and a ultrasonic dispersing instrument with a frequency of 40 kHz and a power of 250 W was used for dispersion for 30 minutes to form a uniform mixture. S4. Copolymer preparation: The same as S4 of Example 1, the polyaniline-pyrrole copolymer with conductivity of 0.05 S / cm was prepared. S5. Composite dispersion: The nanotubes, aerogel, quantum dots and copolymer were weighed according to the weight ratio of 55:35:8:5, poured into a beaker, 500 mL of ethanol-deionized water (4:1) mixed solvent was added, and a 40 kHz, 250 W ultrasonic disperser was used for dispersion for 60 minutes, while a magnetic field of 1.0 T was applied, and every 10 minutes the ultrasonic was paused and manually stirred for 3 minutes (speed 300 rpm). The average particle size of the dispersed mixture was 120 nm, and the distribution width was 0.15. S6. Coating coating and curing: After the solar module was wiped with ethanol for 3 times, it was fixed on the dip coating device. The mixed solution was poured into the dip coating tank, and was dipped and pulled out twice at a speed of 8 cm / min. After standing at room temperature for 5 minutes, it was placed in a 120°C oven for curing for 2 hours, while being irradiated with a 365 nm ultraviolet lamp with a light intensity of 10 mW / cm² (distance 8 cm) to promote the chemical bonding of CNQDs with the matrix. Performance test data: After detection, the coating has a red shift of 10.5% in the ultraviolet-visible light absorption, with the light absorption edge red shifted from 380 nm of Example 1 to 420 nm; the electronic lifetime is extended from 2.3 μs to 3.8 μs, an increase of 65.2%; the visible light catalytic efficiency is improved from 58.1% of Example 1 to 72.3%, an increase of 24.1%.

[0023] Example 3: Preparation of super-hydrophobic anti-fouling coating Preparation of raw materials and instruments: Hollow glass microspheres with a particle size of 20±5 μm and a wall thickness of 2±0.5 μm were used as microstructure skeleton material, and perfluorodecyltriethoxysilane was used to further reduce the surface energy. The experimental equipment was added with an autoclave and an environmental scanning electron microscope, and the rest of the raw materials were partially coincident with Example 1. S1. Preparation of titanium dioxide nanotubes: The same as S1 of Example 1, the nanotube array with mixed phase of anatase-rutile (7:3) was prepared. S2. Aerogel modification: In a three-neck flask, 3 mol of tetraethyl orthosilicate, 1 mol of methyltrimethoxysilane and 1 mol of perfluorooctyltriethoxysilane were added, and after being uniformly stirred by magnetic stirring, 100 mL of hydrochloric acid solution with a pH value of 2.5 was slowly added dropwise. Hydrolysis was carried out in a constant-temperature water bath at 60°C for 2 hours to form a transparent sol. 1.00 g of cetyltrimethylammonium bromide template and 3.00 g of hollow glass microbeads were added, and high-speed stirring was carried out at a speed of 1000 rpm for 30 minutes, and then poured into a culture dish, and gelled at room temperature for 24 hours. A pressure of 0.5 MPa was applied during the gelling stage for 2 hours to promote the directional arrangement of the microbeads. The gel was soaked in anhydrous ethanol for 3 times, each time for 24 hours, and then transferred to a supercritical drying instrument, dried at 40°C and 8 MPa for 16 hours, and finally ground and calcined in a muffle furnace at 650°C for 1 hour to obtain a composite aerogel with a porosity of 95% and a density of 0.12 g / cm³. S3. Quantum dot modification: Citric acid and urea were mixed in a mass ratio of 3:1 and placed in a ceramic crucible and pyrolyzed in a muffle furnace at 220°C for 30 minutes. After cooling, it was dissolved in 100 mL of deionized water and ultrasonically dispersed for 30 minutes to obtain a brown-yellow solution. Under ice bath conditions, 5.00 mL of chloroplatinic acid solution was added to the solution, followed by slow dropwise addition of 15.00 mL of sodium borohydride solution, controlling the temperature not to exceed 5°C, and stirring for 1 hour to increase the platinum loading to 2.5%. After the reaction was completed, centrifugation was carried out at a speed of 10000 rpm for 15 minutes, the precipitate was washed with deionized water 3 times, and polydopamine coating was carried out under constant temperature oscillation conditions (150 rpm) at 40°C for 4 hours, and freeze-drying was carried out for 48 hours to obtain graphene quantum dots with a surface roughness Ra=120 nm. S4. Copolymer preparation: According to the S4 step of Example 1, a polyaniline-pyrrole copolymer with an electrical conductivity of 0.05 S / cm was prepared. S5. Composite dispersion: The nanotubes, aerogel, quantum dots and copolymer were weighed in a weight ratio of 55:35:8:5 and poured into a beaker, 500 mL of ethanol-deionized water (4:1) mixed solvent was added, and a 40 kHz, 250 W ultrasonic disperser was used for dispersion for 60 minutes, while a magnetic field of 1.0 T was applied, and every 10 minutes the ultrasonic was paused and manually stirred for 3 minutes (speed 300 rpm). Finally, 0.30 g of polyether modified siloxane was added, and magnetic stirring was carried out for 10 minutes. S6. Micro-nano structure construction and low surface energy modification: The solar module was cleaned with ethanol for 3 times and fixed on the dip coating device. The mixed solution was poured into the dip coating tank and dipped and pulled for 3 times at a speed of 5 cm / min, with an interval of 15 seconds each time. The coated module was treated in an environment of 60°C and 80% humidity for 36 hours to form a hierarchical structure with 15 μm pits and 80 nm protrusions, and the density of the nano protrusions was 1.2 x 10 7 Finally, the module was immersed in a 0.5wt% perfluorodecyltriethoxysilane / ethanol solution for 10 minutes and dried at 60°C for 2 hours, and the surface energy was reduced to 10.2 mN / m. Performance test data: In the anti-staining performance test, the amount of dust and sand attached to the coating was 1.8 mg / cm after 2 hours of wind and sand box test, which was significantly lower than the 5.2 mg / cm of the traditional coating; the number of washes under a pressure of 500 g / cm was 8000 times, which was much higher than the 5000 times of the traditional coating; and the anti-icing time was 210 seconds in the -15°C water spray test, which was 1.75 times of the 120 seconds of the traditional coating.

[0024] Preparation of a traditional titanium dioxide coating Basic raw materials and instruments: P25 titanium dioxide nanoparticles and ethanol were used as raw materials, and the experimental equipment included an ultrasonic cleaning machine, a general electric heating air drying oven, and a dip coating device.

[0025] S1. Dispersion preparation: 50.00 g of P25 nanoparticles were added to 50.00 mL of ethanol and placed in an ultrasonic cleaning machine with a power of 150 W for dispersion for 30 minutes to form a uniform suspension without magnetic field assistance.

[0026] S2. Coating coating and curing: The cleaned solar module was fixed on the dip coating device, and the module was dipped into the suspension at a pulling speed of 10 cm / min, pulled up after staying for 3 seconds, and pulled only once. Then the module was placed in a 100°C electric heating air drying oven for 1 hour without ultraviolet light irradiation, and a traditional titanium dioxide coating with a thickness of about 150 nm was obtained.

[0027] Performance gap analysis: According to the relevant standard detection, the water contact angle of the coating was 158°, while that of the comparative example was only 110°, and the hydrophobic performance decreased by 30.4%; the photocatalytic efficiency reached 92.3% within 3 hours, while that of the comparative example was only 65.1%, and the degradation capacity decreased by 29.3%; in terms of self-cleaning period, the example 1 could reach 30 days, while the comparative example could only reach 7 days, and the maintenance frequency was 4 times higher than that of the example 1, which highlighted the superiority of the application in super-hydrophobic, photocatalytic and long-acting self-cleaning performance.

[0028] The performance of the examples and the comparative examples is compared as follows: Table 1

[0029] Summary: The water contact angles of Examples 1-3 are all more than 150°, increased by 43%-47% compared with the comparative examples; the photocatalytic degradation rate is increased by 38%-47%, and the photoelectric conversion efficiency is increased by 3.7-4.4 times, verifying the synergistic effect of the nanotube-aerogel-quantum dot composite structure, wherein Example 2 has a significantly enhanced visible light response ability due to the introduction of carbon nanohorns CNQDs.

[0030] The anti-staining performance of the examples and the comparative examples is compared as follows: Table 2

[0031] Summary: The micro-nano composite structure constructed by hollow glass beads and perfluoro silane modification reduces the dust adhesion amount by 65.4%, increases the washable times by 60%, and reduces the rolling angle by 60%, indicating that the synergistic effect of the hierarchical rough structure and the low surface energy on the coating surface effectively improves the anti-particle adhesion ability and mechanical durability, meeting the long-term outdoor use requirements.

[0032] The visible light catalytic aging of the examples and the comparative examples is compared as follows: Table 3

[0033] Summary: The micro-nano composite structure constructed by hollow glass beads and perfluoro silane modification reduces the dust adhesion amount of Example 3 by 65.4% compared with the comparative examples, increases the washable times by 60%, and reduces the rolling angle by 60%. This proves that the synergistic effect of the hierarchical rough structure and the low surface energy coating can effectively resist outdoor dust pollution and improve the mechanical durability.

[0034] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A nanocoating for self-cleaning of a polycrystalline solar module, characterized in that, The following weight parts of raw materials are used: titanium dioxide nanotubes 50-60 parts, fluorosilane modified silica aerogel 30-40 parts, graphene quantum dots 5-10 parts, polyaniline-pyrrole copolymer 3-8 parts; The titanium dioxide nanotubes are prepared by a hydrothermal method, and the reaction formula is: ； ； The fluorosilane modified silica aerogel is prepared by a cetyltrimethylammonium bromide template method, and the aerogel porosity is 85-95%, and the average pore size is 15-25 nm; the nanocoating also introduces carbon nanohorn modified carbon nitride quantum dots, and the mass of the carbon nanohorn modified carbon nitride quantum dots is 5-10% of the mass of the titanium dioxide nanotubes, and the carbon nanohorn modified carbon nitride quantum dots are prepared by reacting 5,10,15,20-tetra(4-carboxyphenyl)porphyrin with melamine at 200-300°C for 3 hours under a nitrogen atmosphere.

2. The nano-coating for self-cleaning multi-crystalline solar modules according to claim 1, characterized in that, The surface of the graphene quantum dots is modified by dopamine self-polymerization to form a polydopamine coating layer with a thickness of 5-10 nm, and the polydopamine layer is loaded with platinum nanoparticles with a particle size of 2-5 nm, and the loading amount is 1-3% of the mass of the graphene quantum dots.

3. The nano-coating for self-cleaning multi-crystalline solar modules according to claim 1, wherein, The polyaniline-pyrrole copolymer is prepared by microemulsion polymerization, sodium dodecylbenzenesulfonate is used as an emulsifier, and ammonium persulfate is used as an initiator, the reaction temperature is 0-5°C, the reaction time is 12-16 hours, and 3-5% of 3,4-ethylenedioxythiophene units are introduced into the copolymer.

4. The nano-coating for self-cleaning multi-crystalline solar modules of claim 1, wherein, When the fluorosilane modified silica aerogel is prepared, 2-5% of hollow glass microbeads based on the total mass of the silica source are added, the hollow glass microbeads have a particle size of 10-30 μm, a wall thickness of 1-3 μm, and are filled with perfluorohexane.

5. The nano-coating for self-cleaning multi-crystalline solar modules of claim 1, wherein, The inner wall of the titanium dioxide nanotubes is loaded with cadmium sulfide quantum dots, which are prepared by an ion exchange method, the particle size of the cadmium sulfide quantum dots is 3-8 nm, and the loading amount is 3-7% of the mass of the titanium dioxide nanotubes.

6. The nano-coating for self-cleaning multi-crystalline solar modules of claim 1, wherein, The surface of the nano coating is formed with micro-nano composite structure by laser etching, the micro structure is a pit with diameter of 10-20 μm and interval of 50-100 μm, and the nano structure is a protrusion with height of 50-100 nm and density of 10 6 -10 7 / cm².

7. A method for the preparation of a nano-coating for self-cleaning multi-crystalline solar modules according to any one of claims 1 to 6, characterized in that, The following steps are included: S1. Preparation of titanium dioxide nanotubes: Place titanium sheets in a 10-15 mol / L NaOH solution, hydrothermal reaction at 150-180°C for 24 hours, wash and calcine at 450-550°C for 2 hours, and introduce 5-10% hydrogen gas by volume during calcination; S2. Preparation of fluorosilane modified silica aerogel: Mix tetraethyl orthosilicate, methyltrimethoxysilane, and 1H,1H,2H,2H-perfluorooctyltriethoxysilane in a molar ratio of 3:1:1, hydrolyze in a hydrochloric acid solution with pH=2-3, add 1-3% of polyvinylpyrrolidone based on the total mass of the silica source, perform solvent exchange and supercritical drying, and calcine at 600-700°C for 1 hour; S3. Synthesis of graphene quantum dots: Mix citric acid and urea in a mass ratio of 3:1, place them in a muffle furnace, pyrolyze at 200-250°C for 30 minutes, cool, dissolve in deionized water, add chloroplatinic acid solution, and reduce with sodium borohydride; S4. Preparation of polyaniline-pyrrole copolymer: Dissolve aniline, pyrrole, and 3,4-ethylenedioxythiophene in a 0.5-1 mol / L hydrochloric acid solution in a molar ratio of 6:3:1, add 1-2% of sodium dodecylbenzenesulfonate based on the total mass of the monomers, add ammonium persulfate initiator at 0-5°C, and react for 12-16 hours; S5. Complex dispersion: the components are mixed in proportion, and a mixed solvent of ethanol and deionized water is added, ultrasonic dispersion is performed for 30-60 minutes, the ultrasonic frequency is 40-60 kHz, the power is 200-300 W, and a magnetic field of 0.5-1 T is applied during dispersion; S6. Coating coating: the mixed solution is coated on the surface of the solar module by using the dip coating method, the dip coating speed is 5-10 cm / min, the pulling number is 2-3 times, and after coating, curing is performed at 100-120℃ for 1-2 hours, and during curing, ultraviolet light with a wavelength of 365 nm is irradiated, and the light intensity is 5-10 mW / cm².

8. The method for the preparation of a nano-coating for self-cleaning multi-crystalline solar modules according to claim 7, characterized in that, In the step S5, the volume ratio of ethanol to deionized water in the mixed solvent is 4:1, and 0.1-0.5% of polyether modified polydimethylsiloxane is added to the mixed solution as a leveling agent.

9. The method of claim 7, wherein the method further comprises: In the step S6, the coated module is subjected to humidity treatment at 50-60℃ for 24-48 hours, and the relative humidity is 70-80%.

10. The method of claim 7, wherein the method further comprises: In the step S1, the length-diameter ratio of the titanium dioxide nanotubes prepared is 50-100, and the fluorescence quantum yield of the graphene quantum dots prepared in the step S3 is 30-40%.

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