A nano-coating for self-cleaning polycrystalline solar modules and method of manufacture

Abstract

The application 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, wherein the coating is composed of titanium dioxide nanotubes, fluorosilane modified silica aerogel, graphene quantum dots and polyaniline-polyazole copolymer; the titanium dioxide nanotubes are prepared through a hydrothermal reaction and calcination, the aerogel is synthesized through a sol-gel method, the quantum dots are obtained through pyrolysis reduction, and the conductive polymer is obtained through oxidation polymerization; the components are dispersed in a solvent in proportion, ultrasonic dispersion is carried out after the addition of a leveling agent, the solar module is coated through a dip coating method, and the coating is formed through drying and ultraviolet curing. The self-cleaning nano coating is composed of multiple components, forms a multistage rough structure, realizes superhydrophobicity, widens a light response range, improves photocatalytic efficiency, improves electrical performance and increases photoelectric conversion efficiency.

Description

TECHNICAL FIELD

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

[0006] The purpose of the present application is achieved by the following technical solutions:

[0007] A nano coating for self-cleaning polycrystalline solar modules is made from the following raw materials by weight: 50-60 parts of titanium dioxide nanotubes, 30-40 parts of fluorosilane modified silica aerogel, 5-10 parts of graphene quantum dots, and 3-8 parts of polyaniline-pyrrole copolymer.

[0008] The titanium dioxide nanotubes are prepared by a hydrothermal method, and the reaction formula is:

[0009] ; ;

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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

[0016] Preferably, the method for preparing the nanocoating according to any one of the above-mentioned methods includes the following steps:

[0017] 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.

[0018] 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;

[0019] 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;

[0020] 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;

[0021] 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;

[0022] 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 and an intensity of 5-10 mW / cm² is irradiated during curing.

[0023] 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.

[0024] 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%.

[0025] 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%.

[0026] Compared with the prior art, the beneficial effects of the present application are:

[0027] 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.

[0028] 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.

[0029] 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

[0030] Fig. 1 is a nano coating preparation flow chart for self-cleaning polycrystalline solar modules proposed by the present application;

[0031] Fig. 2 is a comparison bar chart of water contact angle and photocatalytic degradation rate of the examples and comparative examples;

[0032] Fig. 3 is a comparison line chart of dust adhesion amount and rolling angle of the examples and comparative examples;

[0033] Fig. 4 is a visible light catalytic aging fitting curve of the examples and comparative examples. DETAILED DESCRIPTION

[0034] According to Figs. 1 to 4 , the specific embodiments of the present application are as follows:

[0035] Example 1: Preparation of standard self-cleaning nano coating

[0036] Materials and instrument preparation:

[0037] Titanium sheets with purity of 99.5%, size of 5 cm x 5 cm x 0.5 mm were used as the base 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 to prepare 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, and polyether modified polydimethylsiloxane was used as a leveling agent. The 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.

[0038] S1. Preparation of titanium dioxide nanotubes:

[0039] Titanium sheets were 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 sheets were 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, the titanium sheets were 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 sheets were 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.

[0040] S2. Preparation of fluorosilane modified silica aerogel:

[0041] 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 petri 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°.

[0042] S3. Graphene quantum dot synthesis:

[0043] Citric acid and urea were mixed in a mass ratio of 3:1 and placed in a ceramic crucible for pyrolysis at 220°C for 30 minutes in a muffle furnace. 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, controlling the temperature not to exceed 5°C, and stirring for 1 hour. After the reaction was completed, centrifugation was performed at 10000 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%.

[0044] S4. Polyaniline-pyrrole copolymer preparation:

[0045] 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, keeping the reaction temperature not to exceed 5°C, and continuous stirring was performed 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.

[0046] S5. Composite dispersion:

[0047] Nanotubes, aerogel, quantum dots, and copolymer were weighed in a weight ratio of 55:35:8:5, poured into a beaker, 500 mL of ethanol-deionized water (4:1) mixed solvent was added, and dispersion was performed using a 40 kHz, 250 W ultrasonic disperser for 45 minutes, while applying a magnetic field of 0.8T (direction 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 test showed an average particle size of 120 nm and a distribution width of 0.15.

[0048] S6. Coating application:

[0049] 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 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.

[0050] Performance test data:

[0051] 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.

[0052] Example 2: Preparation of enhanced photocatalytic coating

[0053] Preparation of raw materials and instruments:

[0054] Titanium sheets with purity of 99.5%, size of 5 cm x 5 cm x 0.5 mm were used as base 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, and polyether modified polydimethylsiloxane was used as leveling agent. The experimental equipment includes a polytetrafluoroethylene lined hydrothermal reactor, a supercritical drying instrument, an ultrasonic dispersing instrument, a magnetic field generator and a ultraviolet curing box, and tetra(4-carboxyphenyl) porphyrin and melamine are added as raw materials for preparing carbon nanohorns CNQDs, and a tube furnace and a high-resolution transmission electron microscope are used for preparation and characterization.

[0055] S1. Preparation of CNQDs:

[0056] Porphyrin and melamine were mixed in a mass ratio of 1:5 and placed in a quartz boat in a tube furnace, nitrogen 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.

[0057] S2. Modification of nanotubes:

[0058] 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 is 280 m² / g, the aspect ratio is 60:1, and the light absorption edge is red shifted to 420 nm.

[0059] S3. Quantum dot complex:

[0060] The prepared CNQDs were added at a ratio of 8% of the mass of the titanium dioxide nanotubes, and a 40 kHz, 250 W ultrasonic disperser was used for dispersion for 30 minutes to form a uniform mixture.

[0061] S4. Copolymer preparation:

[0062] The polyaniline-pyrrole copolymer with a conductivity of 0.05 S / cm was prepared according to the S4 step of Example 1.

[0063] S5. Composite dispersion:

[0064] The nanotubes, aerogel, quantum dots, and copolymer were weighed at a weight ratio of 55:35:8:5, poured into a beaker, 500 mL of an 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 the ultrasonic was paused every 10 minutes 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.

[0065] S6. Coating application and curing:

[0066] The solar module was wiped with ethanol for 3 times and fixed on the dip coating device. The mixture was poured into the dip coating tank, and 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 a 365 nm ultraviolet lamp with a light intensity of 10 mW / cm² was used for irradiation (distance 8 cm) to promote the chemical bonding of CNQDs with the matrix.

[0067] Performance test data:

[0068] After detection, the coating had a red shift in the ultraviolet-visible light absorption, with the light absorption edge red shifted from 380 nm in Example 1 to 420 nm, with a red shift amplitude of 10.5%; the electronic lifetime was extended from 2.3 μs to 3.8 μs, with an extension of 65.2%; and the visible light catalytic efficiency was improved from 58.1% in Example 1 to 72.3%, with an improvement of 24.1%.

[0069] Example 3: Preparation of superhydrophobic anti-staining coating

[0070] Preparation of raw materials and equipment:

[0071] Hollow glass microbeads with a particle size of 20±5 μm and a wall thickness of 2±0.5 μm were used as the microstructure skeleton material, and perfluorodecyltriethoxysilane was used to further reduce the surface energy. The experimental equipment was supplemented with a high-pressure reactor and an environmental scanning electron microscope, and the remaining raw materials were partially coincident with those of Example 1.

[0072] S1. Preparation of titanium dioxide nanotubes:

[0073] The same as S1 of Example 1, the nanotube array of mixed phase (7:3) of anatase-rutile was prepared.

[0074] S2. Aerogel modification:

[0075] In a three-necked 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 after high-speed stirring at a speed of 1000 rpm for 30 minutes, they were poured into a culture dish and gelled at room temperature for 24 hours. A pressure of 0.5 MPa was applied during the gelation 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 for drying at 40°C and 8 MPa for 16 hours. Finally, it was 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.

[0076] S3. Quantum dot modification:

[0077] 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 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, with the temperature controlled to not exceed 5°C. Stirring was carried out 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. After freeze-drying for 48 hours, graphene quantum dots with a surface roughness Ra of 120 nm were obtained.

[0078] S4. Copolymer preparation:

[0079] The same as S4 of Example 1, a polyaniline-pyrrole copolymer with an electrical conductivity of 0.05 S / cm was prepared.

[0080] S5. Composite dispersion:

[0081] 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). Finally, 0.30 g of polyether modified silicone was added and magnetically stirred for 10 minutes.

[0082] S6. Micro-nano structure construction and low surface energy modification:

[0083] 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 the module was dipped and pulled out at a speed of 5 cm / min for 3 times, 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 1.2×10 7 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 the module was dipped and pulled out at a speed of 5 cm / min for 3 times, 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 1.2×10

[0084] Performance test data:

[0085] In the anti-staining performance test, after 2 hours of sand and wind box test, the dust adhesion of the coating was 1.8 mg / cm², which was significantly lower than the 5.2 mg / cm² of the traditional coating; the number of washes under a pressure of 500 g / cm² reached 8000 times, far exceeding the 5000 times of the traditional coating; in the-15°C water spray test, the anti-icing time was 210 seconds, which was 1.75 times of the 120 seconds of the traditional coating.

[0086] Comparative example: preparation of traditional titanium dioxide coating

[0087] Basic raw materials and instruments:

[0088] P25 titanium dioxide nanoparticles and ethanol were used as raw materials, and the experimental equipment included an ultrasonic cleaner, a general electric heating air drying oven and a dip coating device.

[0089] S1. Dispersion preparation:

[0090] 50.00 g of P25 nanoparticles were added to 50.00 mL of ethanol and placed in an ultrasonic cleaner with a power of 150 W for dispersion for 30 minutes to form a uniform suspension without magnetic field assistance.

[0091] S2. Coating coating and curing:

[0092] 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, stayed for 3 seconds, and then pulled up, only once. Then the module was placed in an electric hot air drying oven at 100°C for curing for 1 hour without ultraviolet light irradiation, to obtain a conventional titanium dioxide coating with a thickness of about 150 nm.

[0093] Performance gap analysis:

[0094] According to relevant standards, the water contact angle of the coating was 158°, while that of the comparative example was only 110°, with a decrease of 30.4% in hydrophobic performance; the photocatalytic efficiency reached 92.3% within 3 hours, while that of the comparative example was only 65.1%, with a decrease of 29.3% in degradation capacity; the self-cleaning period of Example 1 was 30 days, while that of the comparative example was only 7 days, with a 4-fold increase in maintenance frequency compared with Example 1, highlighting the superiority of the present application in super-hydrophobic, photocatalytic and long-acting self-cleaning performance.

[0095] Performance comparison of examples and comparative examples, as follows:

[0096] Table 1

[0097]

[0098] Summary: The water contact angles of Examples 1-3 were all more than 150°, with an increase of 43%-47% compared with the comparative example; the photocatalytic degradation rate was increased by 38%-47%, and the photoelectric conversion efficiency was increased by 3.7-4.4 times, verifying the synergistic effect of the nanotube-aerogel-quantum dot composite structure, among which Example 2 had significantly enhanced visible light response ability due to the introduction of carbon nanohorns CNQDs.

[0099] Performance comparison of examples and comparative examples, as follows:

[0100] Table 2

[0101]

[0102] Summary: The micro-nano composite structure constructed by hollow glass beads and perfluorosilane modification reduced the amount of sand and dust attached by 65.4%, increased the number of washes by 60%, and reduced the rolling angle by 60%, indicating that the hierarchical rough structure and low surface energy on the coating surface synergistically enhanced the anti-particle adhesion ability and mechanical durability, meeting the long-term outdoor use requirements.

[0103] Comparison of visible light catalytic aging of examples and comparative examples, as follows:

[0104] Table 3

[0105]

[0106] Summary: By the hollow glass microspheres and perfluorosilane modified micro-nano composite structure, the dust adhesion amount of Example 3 is reduced by 65.4% compared with the comparative example, the washing resistance times is increased by 60%, and the rolling angle is reduced by 60%. This proves that the synergistic effect of hierarchical rough structure and low surface energy coating can effectively resist outdoor dust pollution and improve mechanical durability.

[0107] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely divergences of the principles and spirit of the application and that numerous modifications, changes, substitutions, and alterations can be made thereto without departing from the spirit and scope of the application as defined by the appended claims.

Claims

1. A nano-coating for self-cleaning polycrystalline solar modules, characterized in that, It is made from the following raw materials in parts by weight: 50-60 parts titanium dioxide nanotubes, 30-40 parts fluorosilane-modified silica aerogel, 5-10 parts graphene quantum dots, and 3-8 parts polyaniline-polypyrrole copolymer. The titanium dioxide nanotubes were prepared by placing titanium sheets in a 10-15 mol / L NaOH solution and hydrothermally reacting them at 150-180℃ for 24 hours. After washing, they were calcined at 450-550℃ for 2 hours, with 5-10% hydrogen gas being introduced during calcination. 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 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. The graphene quantum dots are 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; 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. The surface of the nano-coating is laser-etched to form a micro-nano composite structure. 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. 6 -10 7 pcs / cm² 2. The nano-coating for self-cleaning polycrystalline solar modules according to claim 1, characterized in that, The polyaniline-polypyrrole copolymer is prepared by microemulsion polymerization, using sodium dodecylbenzenesulfonate as emulsifier and ammonium persulfate as initiator. The reaction temperature is 0-5℃ and the reaction time is 12-16 hours. 3-5% of 3,4-ethylenedioxythiophene units are introduced into the copolymer.

3. The nano-coating for self-cleaning polycrystalline solar modules according to claim 1, characterized in that, The inner wall of the titanium dioxide nanotubes 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 nanotubes.

4. A method for preparing a nano-coating for a self-cleaning polycrystalline solar module according to any one of claims 1-3, characterized in that, 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. Preparation of fluorosilane-modified silica aerogel: Tetraethyl orthosilicate, methyltrimethoxysilane, and 1H,1H,2H,2H-perfluorooctyltriethoxysilane were mixed in a molar ratio of 3:1:1 and hydrolyzed in hydrochloric acid solution with pH=2-3. Polyvinylpyrrolidone accounting for 1-3% of the total mass of the silicon source was added, followed by solvent exchange and supercritical drying, and calcination at 600-700℃ for 1 hour. S3. Synthesis of graphene quantum dots: Citric acid and urea are mixed at a mass ratio of 3:1, placed in a muffle furnace, pyrolyzed at 200-250℃ for 30 minutes, cooled and dissolved in deionized water, chloroplatinic acid solution is added, and reduced with sodium borohydride. S4. Preparation of polyaniline-polypyrrole copolymer: Aniline, pyrrole and 3,4-ethylenedioxythiophene are dissolved in 0.5-1 mol / L hydrochloric acid solution in a molar ratio of 6:3:

1. Sodium dodecylbenzenesulfonate is added at 1-2% of the total mass of monomers. Ammonium persulfate initiator is added at 0-5℃ and the reaction is carried out for 12-16 hours. S5. Composite dispersion: Mix the components in proportion, add a mixed solvent of ethanol and deionized water, and ultrasonically disperse for 30-60 minutes. The ultrasonic frequency is 40-60kHz and the power is 200-300W. Apply a magnetic field of 0.5-1T during dispersion. S6. Coating: The mixture is applied to the surface of the solar module by dip coating at a speed of 5-10 cm / min and 2-3 lift-off cycles. After coating, it is cured at 100-120℃ for 1-2 hours. During curing, it is irradiated with ultraviolet light with a wavelength of 365nm and a light intensity of 5-10mW / cm².

5. The method for preparing a nano-coating for a self-cleaning polycrystalline solar module according to claim 4, characterized in that, In 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 mixture as a leveling agent.

6. The method for preparing a nano-coating for a self-cleaning polycrystalline solar module according to claim 4, characterized in that, In step S6, the coated components are subjected to humidity treatment at 50-60°C for 24-48 hours, with a relative humidity of 70-80%.

7. The method for preparing a nano-coating for a self-cleaning polycrystalline solar module according to claim 4, characterized in that, The titanium dioxide nanotubes prepared in step S1 have an aspect ratio of 50-100, and the graphene quantum dots prepared in step S3 have a fluorescence quantum yield of 30-40%.

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