CN110408316A - Preparation method of photocatalytic super-hydrophobic coating - Google Patents

Abstract

The invention relates to a method for preparing a photocatalytic super-hydrophobic coating. The invention modifies BiOI/MoS2/CdS nanoparticles with low surface energy substances to increase the roughness of the coating and reduce the low surface energy of the coating, so that The coating has a high-efficiency hydrophobic effect, and cadmium sulfide itself has good adsorption and photocatalysis, but its band gap is wide, and the recombination rate of photogenerated electron-hole pairs is high, while the gap band of bismuth oxyiodide is very narrow, and BiOI/ The heterojunction formed by MoS2/CdS coupling greatly improves the photocatalytic performance of the composite material. Cadmium sulfide, bismuth oxyiodide and molybdenum disulfide are all nanomaterials. In addition, the present invention selects sodium sulfate nonahydrate as the sulfur source. Obtaining cadmium sulfide nanoparticles with small size improves the hydrophobic performance of the superhydrophobic coating, and also improves the wear resistance ability.

Description

A kind of preparation method of photocatalytic superhydrophobic coating

technical field

The invention belongs to the technical field of superhydrophobic materials, and in particular relates to a preparation method of a photocatalyzed superhydrophobic coating.

Background technique

The surface of an object with a water contact angle greater than 90° is hydrophobic, while the surface of an object with a water contact angle above 150° is superhydrophobic. The superhydrophobic surface is not only hydrophobic but also oleophobic. The superhydrophobic surface has excellent performance, so it has broad application prospects in many fields, such as self-cleaning, anti-corrosion, anti-icing, drag reduction, and antifouling. With the rapid development of the economy, the glass and high-rise exterior walls used in modern buildings will inevitably be attached to some organic or inorganic dirt due to long-term exposure to nature. Manual cleaning is difficult to achieve because of its low efficiency, high cost, and high risk. . Therefore, it is necessary to develop a superhydrophobic coating with photocatalytic activity, which can not only realize superhydrophobic self-cleaning, but also degrade organic pollutants under the irradiation of visible light, and further realize its self-cleaning function.

At present, the research on the self-cleaning performance of superhydrophobic self-cleaning coatings is limited to the use of water droplets to wash away hydrophilic pollutants, while there are few studies on the photocatalytic degradation of oily organic pollutants, and most of the research is limited to the Research on common nanomaterials such as titanium dioxide and zinc oxide with ultraviolet photocatalytic activity. Since ultraviolet light only accounts for 5% of sunlight, this severely limits the utilization of natural sunlight by photocatalytically active materials, and ordinary inorganic nanomaterials have poor dispersion and are easy to form due to their large specific surface junctions. Aggregates of different sizes not only seriously affect the photocatalytic activity, but also affect the hydrophobic performance.

In view of the above reasons, the present invention is proposed.

Contents of the invention

In order to solve the above problems in the prior art, the invention provides a method for preparing a photocatalytic superhydrophobic coating, the superhydrophobic coating of the present invention is mainly made of bismuth oxyiodide/molybdenum disulfide/cadmium sulfide photocatalytic nanoparticles The photocatalytic performance of bismuth oxyiodide/molybdenum disulfide/cadmium sulfide has been greatly improved. The addition of cadmium sulfide not only improves the photocatalytic performance, but also significantly improves the ability to degrade organic matter, improves the self-cleaning ability, and also improves the hydrophobicity. performance.

In order to achieve the above object, the present invention adopts the following technical solutions:

A method for preparing a photocatalytic superhydrophobic coating, comprising the steps of:

(1) Substrate pretreatment: After derusting the substrate, soak it in NaOH solution with a mass fraction of 2-4%, heat it, then soak it in absolute ethanol and ultrasonically clean it for 5 minutes, take it out and clean it with deionized water, and then immerse it in hydrochloric acid In the solution for 3-5min, wash with deionized water, dry, and set aside;

(2) Preparation of bismuth oxyiodide: bismuth nitrate pentahydrate and potassium oxyiodide were added to ethylene glycol for dissolution, and the ethylene glycol solution of potassium iodide was slowly added to the ethylene glycol solution of bismuth nitrate pentahydrate under stirring In the process, after stirring for 0.8-1.2h, move it into a reaction kettle, heat for reaction, cool, centrifuge, and wash to obtain bismuth oxyiodide;

(3) Preparation of BiOI/MoS ₂ : Dissolve sodium molybdate in deionized water, add thioacetamide under stirring conditions, stir for 0.8-1.2h, add bismuth oxyiodide prepared in step (2) and stir for 3.5- 4.5h, heated in the reactor at 180°C for 24h, centrifuged, and dried at 60°C for 8h to obtain BiOI/MoS ₂ ;

(4) Preparation of BiOI/MoS ₂ /CdS: Add cadmium chloride hydrate to the aqueous solution of cetyltrimethylammonium bromide, ultrasonically disperse it evenly to form solution A, add sodium sulfide nonahydrate to cetyl trimethylammonium bromide In an aqueous solution of trimethylammonium bromide, ultrasonically disperse uniformly to form solution B, and add solution B dropwise to solution A to form a mixed solution. Take 0.0343-0.1028g of BiOI/MoS ₂ prepared in step (3) Dissolve in 10ml of deionized water, stir evenly, add to the mixed solution, stir for 8-12h, heat for reaction, cool, centrifuge, dry to obtain BiOI/MoS ₂ /CdS;

(5) BiOI/MoS ₂ /CdS modified by low surface energy substances: Mix polydimethylsiloxane and curing agent evenly, then add it to a mixed solvent of hexane and absolute ethanol, and disperse evenly by ultrasonication for 25-35min. Then add the BiOI/MoS ₂ /CdS prepared in step (4), disperse uniformly by ultrasonication for 25-35min, spray on the surface of the substrate, and cure at 110-130°C for 0.8-1.2h to obtain the photocatalytic superhydrophobic coating.

The main mechanism of the photocatalytic performance and hydrophobic performance of the superhydrophobic coating of the present invention is: bismuth oxyiodide is a semiconductor with a narrower band gap, while the band gap of cadmium sulfide is wider, and its photogenerated electron-hole pair recombination Molybdenum disulfide is a two-dimensional layered structure similar to graphene, and the layers are connected by van der Waals force. The specific surface area of molybdenum disulfide in the layered structure is large. The combination of bismuth oxyiodide/molybdenum disulfide/cadmium sulfide composite photocatalyst It can form a heterojunction, has more active sites exposed on its surface, has good adsorption performance, can promote the rapid transfer of electrons, and has a lower photoluminescence spectrum, which can reduce the recombination of photogenerated electron-hole pairs, thereby improving the catalyst photocatalytic performance. The catalyst forms electron-hole pairs under the action of light. Electrons (e ^- ) on the valence band of bismuth oxyiodide/molybdenum disulfide/cadmium sulfide are excited to the high-energy conduction band, forming strong reducing holes (h ⁺ ) and strong oxidizing holes in the valence band and conduction band respectively. Electrons e ^- , e ^- react with oxygen to form oxygen anions O ₂ ^- , h ⁺ and O ₂ ^- can react with organic pollutants to achieve the purpose of degradation, and low surface energy substances are added to the coating to modify BiOI/MoS ₂ /CdS nanoparticles Li can make the surface of the coating have extremely low surface energy, which is beneficial to improve the hydrophobicity.

Further, the substrate is glass, copper sheet or aluminum sheet.

Further, in step (1), the heating temperature is 75-85° C., and the heating time is 4-6 minutes.

Further, in step (2), the mass volume ratio of bismuth nitrate pentahydrate to ethylene glycol is 1.46g:35-45ml, and the mass volume ratio of potassium iodide to ethylene glycol is 0.5g:35-45ml.

Further, the heating temperature in step (2) is 140-160°C, and the reaction time is 12-24h.

Further, the mass volume ratio of sodium molybdate and deionized water in step (3) is 0.015-0.045g:60ml, the mol ratio of thioacetamide and sodium molybdate is 1:3, sodium molybdate and bismuth oxyiodide The mass ratio is 0.015-0.045:1.

Further, the mass volume ratio of cadmium chloride hydrate, cetyltrimethylammonium bromide and water in solution A in step (3) is 2.2841g:0.05-0.1g:20ml, and sodium sulfide nonahydrate in solution B , The mass volume ratio of cetyltrimethylammonium bromide and water is 2.4018g: 0.05-0.1g: 20ml.

Further, in step (4), the heating temperature is 120-180°C, the reaction time is 4-12h, the drying temperature is 55-65°C, and the drying time is 10-14h.

Further, in step (5), the mass ratio of hexane to absolute ethanol is 1:2, and the mass ratio of polydimethylsiloxane to curing agent is 10:1.

Further, the curing agent is Sylgard184.

Further, the mass ratio of polydimethylsiloxane to BiOI/CdS in step (5) is 4:1-4.

Compared with prior art, the beneficial effect of the present invention is:

(1) Cadmium sulfide itself has good adsorption and photocatalytic properties, but its band gap is wide, and the photogenerated electron-hole pair recombination rate is high, while the gap band of bismuth oxyiodide is very narrow, and the coupling of BiOI/MoS ₂ /CdS The formed heterojunction can play a synergistic role, reducing the gaps in the material structure, increasing the surface area, increasing the highly active parts of the composite catalyst, accelerating the transfer of electrons, and inhibiting the recombination of photogenerated electrons and holes. The photocatalytic performance has been greatly improved, and the photocatalytic degradation effect of the composite catalyst material is 2-3 times higher than that of the pure catalyst. When BiOI/MoS2/CdS is added to the superhydrophobic coating, the coating is also hydrophobic. And photocatalysis, which is of great significance to purify the environment;

(2) Cadmium sulfide, bismuth oxyiodide, and molybdenum disulfide are all nanomaterials, which are prone to aggregation during the preparation process. In order to avoid the formation of larger crystal materials due to aggregation, the surfactant hexadecyl trisulfide is added during the preparation process. After methyl ammonium bromide obtains the larger nano-crystal material of specific surface area, hexadecyl trimethyl ammonium bromide has not only played the effect of stabilizing agent, but also plays the effect of suppressing grain excessive growth, and the present invention selects nine Sodium sulfate water can be used as a sulfur source to obtain small cadmium sulfide nanoparticles, which improves the hydrophobicity of the superhydrophobic coating and also improves the wear resistance;

(3) Modification of BiOI/MoS ₂ /CdS nanoparticles with polydimethylsiloxane low surface energy substances can not only increase the roughness of the coating, but also reduce the low surface energy of the coating, making the coating highly hydrophobic Effect.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is the scanning electron micrograph of the bismuth oxyiodide prepared by the embodiment of the present invention 1;

Fig. ₂ is the scanning electron micrograph of BiOI/MoS prepared in Example 1 of the present invention;

Fig. 3 is a scanning electron micrograph of BiOI/MoS ₂ /CdS prepared in Example 1 of the present invention;

Fig. 4 is the curve diagram of C _t /C ₀ value and time in Test Example 1 of the present invention;

Fig. 5 is the contact angle of the superhydrophobic coating prepared in Example 2 of the present invention.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Apparently, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other implementations obtained by persons of ordinary skill in the art without making creative efforts fall within the protection scope of the present invention.

Example 1

A kind of preparation method of photocatalytic superhydrophobic coating of the present embodiment, comprises the steps:

(1) Substrate pretreatment: Preliminarily polish and derust a 2cmx2cmx1cm aluminum sheet with sandpaper, soak it in a NaOH solution with a mass fraction of 2% after derusting, and heat it in a water bath at a constant temperature of 75°C for 6 minutes to remove surface oil stains, then Soak in absolute ethanol and ultrasonically clean for 5 minutes, take it out and wash it with deionized water, then immerse it in a hydrochloric acid solution with a concentration of 3mol/L for 3-5 minutes, wash it with deionized water, dry it, and set it aside;

(2) Preparation of bismuth oxyiodide: 1.46g bismuth nitrate pentahydrate and 0.5g potassium oxyiodide were added to 40ml ethylene glycol and stirred for 15min to dissolve completely, and the ethylene glycol solution of potassium iodide was slowly added to In the ethylene glycol solution of bismuth nitrate pentahydrate, after stirring for 1 hour, transfer the mixed solution into the reaction kettle, and heat it at 140°C for 24 hours. After the reaction kettle is naturally cooled to room temperature, centrifuge the product, and wash it with absolute ethanol and deionized Water was washed three times respectively to obtain bismuth oxyiodide;

(3) Preparation of BiOI/MoS ₂ : Dissolve 0.015g of sodium molybdate in 60ml of deionized water, add thioacetamide under stirring conditions, the molar ratio of thioacetamide to sodium molybdate is 1:3 , stirred for 0.8h, added 1g of bismuth oxyiodide prepared in step (2) and stirred for 3.5h, heated at 180°C in the reactor for 24h, centrifuged to obtain the product, dried at 60°C for 8h, to obtain BiOI/MoS ₂ ;

(4) Preparation of BiOI/MoS ₂ /CdS: Add 2.2841g of cadmium chloride hydrate to 20ml of aqueous solution containing 0.05g of hexadecyltrimethylammonium bromide, disperse for 20min with ultrasound to form solution A uniformly, and dissolve 2.4018 g of sodium sulfide nonahydrate was added to 20ml of aqueous solution containing 0.05g of cetyltrimethylammonium bromide, ultrasonically dispersed to form solution B, and solution B was added dropwise to solution A to form a mixed solution. Dissolve 0.0343g of BiOI/MoS ₂ prepared in step (3) in 10ml of deionized water and stir evenly into the mixed solution, stir for 8-12h, react under hydrothermal heat at 120°C for 12h, cool to room temperature, and centrifuge The product was dried at 55°C for 14 hours to obtain BiOI/MoS ₂ /CdS;

(5) BiOI/MoS ₂ /CdS modified by low surface energy substances: Mix polydimethylsiloxane and curing agent Sylgard184 uniformly at a mass ratio of 10:1, take 0.8g of it and add it to 2.4g hexane and 4.8g In the mixed solvent of absolute ethanol, disperse uniformly by ultrasonication for 25 minutes, then add the BiOI/MoS ₂ /CdS prepared in step (4), the mass ratio of polydimethylsiloxane to BiOI/MoS ₂ /CdS is 4:1, Ultrasonic for 25 minutes to disperse evenly, spray directly onto the substrate surface, spray distance 20-25cm, and cure at 110°C for 1.2h to obtain the photocatalytic superhydrophobic coating.

The scanning electron micrograph of bismuth oxyiodide prepared in this example is shown in Figure 1, the scanning electron micrograph of BiOI/MoS ₂ is shown in Figure 2, and the scanning electron micrograph of BiOI/MoS ₂ /CdS is shown in Figure 3.

It can be clearly observed from the figure that BiOI is a spherical flower-like composition composed of nanosheets, and there are various microporous structures evenly distributed between layers. When MoS2 is coupled, the interface between BiOI and MoS2 forms a close contact, and some micropores on the surface of BiOI will be covered, so too much MoS2 cannot be added, otherwise the active sites exposed on the surface of BiOI will be covered, and the opposite will be achieved. Therefore, in the present invention, a specific ratio of BiOI, MoS ₂ , and CdS is selected. The surface of the BiOI/MoS2/CdS nanomaterial prepared by the present invention is composed of cadmium sulfide nanospheres with different sizes, and BiOI/MoS2 nanoparticles are distributed between the surface of the microspheres and the interface. The compact structure is conducive to the rapid transfer of electrons, The formation of electron-hole pairs with low recombination rate improves the photocatalytic performance of the catalyst.

Example 2

A kind of preparation method of photocatalytic superhydrophobic coating of the present embodiment, comprises the steps:

(1) Substrate pretreatment: the copper sheet of 2cmx2cmx1cm is preliminarily polished and derusted with sandpaper, soaked in NaOH solution with a mass fraction of 3% after derusting, and heated in a water bath at a constant temperature of 80°C for 5min to remove surface oil stains, and then Soak in absolute ethanol and ultrasonically clean for 5 minutes, take it out and wash it with deionized water, then immerse it in a hydrochloric acid solution with a concentration of 3mol/L for 3-5 minutes, wash it with deionized water, dry it, and set it aside;

(2) Preparation of bismuth oxyiodide: 1.46g bismuth nitrate pentahydrate and 0.5g potassium oxyiodide were added to 35ml ethylene glycol and stirred for 15min to dissolve completely, and the ethylene glycol solution of potassium iodide was slowly added to In the ethylene glycol solution of bismuth nitrate pentahydrate, after stirring for 1 hour, transfer the mixed solution into the reaction kettle, and heat it at 150°C for 18 hours. After the reaction kettle is naturally cooled to room temperature, the product is centrifuged, and washed with absolute ethanol and deionized Water was washed three times respectively to obtain bismuth oxyiodide;

(3) Preparation of BiOI/MoS ₂ : Dissolve 0.025g of sodium molybdate in 60ml of deionized water, add thioacetamide under stirring conditions, the molar ratio of thioacetamide to sodium molybdate is 1:3 , stirred for 1 h, added 1 g of bismuth oxyiodide prepared in step (2) and stirred for 4 h, heated in the reactor at 180° C. for 24 h, centrifuged to obtain the product, and dried at 60° C. for 8 h to obtain BiOI/MoS ₂ ;

(4) Preparation of BiOI/MoS ₂ /CdS: Add 2.2841g of cadmium chloride hydrate to 20ml of aqueous solution containing 0.075g of hexadecyltrimethylammonium bromide, disperse for 20min with ultrasound to form solution A, and mix 2.4018 1 g of sodium sulfide nonahydrate is added to 20 ml of aqueous solution containing 0.075 g of cetyltrimethylammonium bromide, ultrasonically dispersed to form solution B, and solution B is added dropwise to solution A to form a mixed solution. Dissolve 0.0799g of BiOI/MoS ₂ prepared in step (3) in 10ml of deionized water, stir evenly, add to the mixed solution, stir for 8-12h, react with hydrothermal heat at 150°C for 8h, cool to room temperature, and centrifuge The product was dried at 60°C for 12 hours to obtain BiOI/MoS ₂ /CdS;

(5) BiOI/MoS ₂ /CdS modified by low surface energy substances: mix polydimethylsiloxane and curing agent Sylgard184 according to the mass ratio of 10:1, take 0.8g of it and add it to 2.6g hexane and 5.2g In the mixed solvent of absolute ethanol, disperse evenly by ultrasonication for 30 minutes, then add the BiOI/MoS ₂ /CdS prepared in step (4), the mass ratio of polydimethylsiloxane to BiOI/MoS ₂ /CdS is 4:3, Ultrasonic for 30 minutes to disperse evenly, spray directly onto the surface of the substrate with a spraying distance of 20-25 cm, and cure at 120° C. for 1 hour to obtain the photocatalytic superhydrophobic coating.

The present inventor also measured the scanning electron micrographs of bismuth oxyiodide, BiOI/MoS ₂ , and BiOI/MoS ₂ /CdS prepared in this example, and the results were basically consistent with Example 1. Due to limited space, they will not be listed one by one.

Example 3

A kind of preparation method of photocatalytic superhydrophobic coating of the present embodiment, comprises the steps:

(1) Substrate pretreatment: The aluminum sheet of 2cmx2cmx1cm is initially polished and derusted with sandpaper, soaked in NaOH solution with a mass fraction of 4% after derusting, and heated in a water bath at a constant temperature of 85°C for 4min to remove surface oil stains, and then Soak in absolute ethanol and ultrasonically clean for 5 minutes, take it out and wash it with deionized water, then immerse it in a hydrochloric acid solution with a concentration of 3mol/L for 3-5 minutes, wash it with deionized water, dry it, and set it aside;

(2) Preparation of bismuth oxyiodide: 1.46g bismuth nitrate pentahydrate and 0.5g potassium oxyiodide were added to 45ml ethylene glycol and stirred for 15min to dissolve completely, and the ethylene glycol solution of potassium iodide was slowly added to In the ethylene glycol solution of bismuth nitrate pentahydrate, after stirring for 1.2 hours, transfer the mixed solution into the reactor, and heat it at 160°C for 12 hours. Deionized water was washed three times respectively to obtain bismuth oxyiodide;

(3) Preparation of BiOI/MoS ₂ : Dissolve 0.045g of sodium molybdate in 60ml of deionized water, add thioacetamide under stirring conditions, the molar ratio of thioacetamide to sodium molybdate is 1:3 , stirred for 1.2h, added 1g of bismuth oxyiodide prepared in step (2) and stirred for 4.5h, heated in the reactor at 180°C for 24h, centrifuged to obtain the product, dried at 60°C for 8h, to obtain BiOI/MoS ₂ ;

(4) Preparation of BiOI/MoS ₂ /CdS: Add 2.2841g of cadmium chloride hydrate to 20ml of aqueous solution containing 0.1g of hexadecyltrimethylammonium bromide, disperse for 20min with ultrasound to form solution A, and mix 2.4018 g of sodium sulfide nonahydrate was added to 20 ml of aqueous solution containing 0.1 g of cetyltrimethylammonium bromide, ultrasonically dispersed to form solution B, and solution B was added dropwise to solution A to form a mixed solution. Dissolve 0.1028g of BiOI/MoS ₂ prepared in step (3) in 10ml of deionized water and stir evenly into the mixed solution, stir for 8-12h, react under hydrothermal heat at 180°C for 4h, cool to room temperature, and centrifuge The product was dried at 65°C for 10 hours to obtain BiOI/MoS ₂ /CdS;

(5) BiOI/MoS ₂ /CdS modified by low surface energy substances: mix polydimethylsiloxane and curing agent Sylgard184 uniformly at a mass ratio of 10:1, take 0.8g of it and add it to 3.0g hexane and 6g In the mixed solvent of water and ethanol, disperse uniformly by ultrasonication for 35min, then add the BiOI/MoS ₂ /CdS prepared in step (4), the mass ratio of polydimethylsiloxane to BiOI/MoS ₂ /CdS is 1:1, and ultrasonically Disperse uniformly within 35 minutes, spray directly onto the surface of the substrate, spray at a distance of 20-25cm, and cure at 130°C for 0.8h to obtain the photocatalytic superhydrophobic coating.

The present inventor also measured the scanning electron micrographs of bismuth oxyiodide, BiOI/MoS ₂ , and BiOI/MoS ₂ /CdS prepared in this example, and the results were basically consistent with Example 1. Due to limited space, they will not be listed one by one.

Comparative example 1

This comparative example adopts the same method as Example 1 to prepare a photocatalytic superhydrophobic coating, the difference is that step (3) is omitted, step (4) is the preparation of BiOI/CdS, and step (5) is a low surface BiOI/CdS can be modified with energy substances, and the final superhydrophobic coating does not contain molybdenum disulfide.

Comparative example 2

In this comparative example, the photocatalytic superhydrophobic coating is prepared by the same method as in Example 1, the difference is that step (4) is omitted, and step (5) is to modify BiOI/MoS ₂ with low surface energy substances, and the final prepared The superhydrophobic coating does not contain cadmium sulfide.

Comparative example 3

The photocatalytic superhydrophobic coating of this comparative example is prepared in the same way as in Example 1, the difference is that step (3) and step (4) are omitted, and step (5) is modified BiOI with low surface energy substances, and finally The prepared superhydrophobic coating does not contain molybdenum disulfide and cadmium sulfide, but only contains modified bismuth oxyiodide.

Test example 1

The degradation properties of the BiOI/MoS ₂ /CdS prepared in Examples 1-3 and the BiOI/CdS prepared in Comparative Example 1, the BiOI/MoS ₂ prepared in Comparative Example 2, and the BiOI prepared in Comparative Example 3 on the methyl orange solution were tested respectively. Take 30mg of each raw material and add it into 50ml of 20mg/L methyl orange solution, first carry out 30min dark reaction to achieve adsorption equilibrium, irradiate under 20W ultraviolet lamp, and catalyze the reactor into light reaction, and investigate the C _t /C ₀ value at different times , C _t is the concentration of methyl orange solution at time t, C ₀ is the initial concentration of methyl orange solution, the smaller the C _t /C ₀ value, the higher the degradation rate of methyl orange, and the degradation rate is (C ₀ -C _t )/C0×100%, the results are shown in Figure 4.

As can be seen from Figure 4, at the same time, the C _t /C ₀ values of Comparative Examples 1-3 are higher than those of Examples 1-3, indicating that the photocatalytic degradation performance of Comparative Examples 1-3 is poor, and from the comparative examples 1-3 It can be seen from ratios 1-3 that the C _t /C ₀ value at the same moment in comparative example 3 is higher than that of comparative examples 1 and 2, indicating that the degradation performance of bismuth oxyiodide alone is poor, and the two compounds can improve the degradation performance. performance, but significantly lower than the degradation performance of the composite of the three substances, indicating that the heterojunction formed by the coupling of BiOI/MoS ₂ /CdS can play a synergistic role, reducing the voids in the material structure, increasing the surface area, and increasing the composite catalyst. The active part accelerates the transfer of electrons, well inhibits the recombination of photogenerated electrons and holes, the photocatalytic performance of the composite material is greatly improved, and the photocatalytic degradation effect of the composite catalyst material is 2-3 times higher than that of the pure catalyst.

Test example 2

The super-hydrophobic coatings prepared in Examples 1-3 and Comparative Examples 1-3 were tested for wear resistance respectively. The test method: the substrate coated with the super-hydrophobic coating was fixed on a horizontal desktop, and placed in a 1000CW Sandpaper and a 50g weight, drag the sandpaper to a distance of 10cm, and measure the contact angle of the coating after 0, 20, 40, 60, 80, and 100 times of this operation. Contact angle measurement method: use a contact angle tester to measure the contact angle of water droplets on the surface of the film layer. The contact angle value is obtained by measuring the average value of 5 random positions. The static contact angle is measured by the sessile drop method. The superhydrophobic surface (That is, the surface with a static contact angle greater than 150°) was measured using 5 μL water droplets uniformly, and the test results are shown in Table 1.

Table 1

As can be seen from Table 1, the superhydrophobic coatings of Examples 1-3 and Comparative Examples 1-3 are treated with the same number of times of dragging, and the contact angle of Examples 1-3 decreases less, indicating that the prepared superhydrophobic coating of the present invention The wear resistance of the coating is better. When dragging 0 times, the contact angle of the present invention is greater than that of Comparative Examples 1-3, which proves that the superhydrophobic coating of the present invention has better hydrophobic performance. Among them, the contact angle of the superhydrophobic coating prepared in Example 2 is shown in Figure 5. Due to limited space, the contact angles of other examples and comparative examples are not listed one by one.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (10)

1. a preparation method of photocatalytic superhydrophobic coating, is characterized in that, comprises the steps: (1) Substrate pretreatment: After derusting the substrate, soak it in NaOH solution with a mass fraction of 2-4%, heat it, then soak it in absolute ethanol and ultrasonically clean it for 5 minutes, take it out and clean it with deionized water, and then immerse it in hydrochloric acid In the solution for 3-5min, wash with deionized water, dry, and set aside; (2) Preparation of bismuth oxyiodide: bismuth nitrate pentahydrate and potassium oxyiodide were added to ethylene glycol for dissolution, and the ethylene glycol solution of potassium iodide was slowly added to the ethylene glycol solution of bismuth nitrate pentahydrate under stirring In the process, after stirring for 0.8-1.2h, move it into a reaction kettle, heat for reaction, cool, centrifuge, and wash to obtain bismuth oxyiodide; (3) Preparation of BiOI/MoS ₂ : Dissolve sodium molybdate in deionized water, add thioacetamide under stirring conditions, stir for 0.8-1.2h, add bismuth oxyiodide prepared in step (2) and stir for 3.5- 4.5h, heated in the reactor at 180°C for 24h, centrifuged, and dried at 60°C for 8h to obtain BiOI/MoS ₂ ; (4) Preparation of BiOI/MoS ₂ /CdS: Add cadmium chloride hydrate to the aqueous solution of cetyltrimethylammonium bromide, ultrasonically disperse it evenly to form solution A, add sodium sulfide nonahydrate to cetyl trimethylammonium bromide In an aqueous solution of trimethylammonium bromide, ultrasonically disperse uniformly to form solution B, and add solution B dropwise to solution A to form a mixed solution. Take 0.0343-0.1028g of BiOI/MoS ₂ prepared in step (3) Dissolve in 10ml of deionized water, stir evenly, add to the mixed solution, stir for 8-12h, heat for reaction, cool, centrifuge, dry to obtain BiOI/MoS ₂ /CdS; (5) BiOI/MoS ₂ /CdS modified by low surface energy substances: Mix polydimethylsiloxane and curing agent evenly, then add it to a mixed solvent of hexane and absolute ethanol, and disperse evenly by ultrasonication for 25-35min. Then add the BiOI/MoS ₂ /CdS prepared in step (4), disperse uniformly by ultrasonication for 25-35min, spray on the surface of the substrate, and cure at 110-130°C for 0.8-1.2h to obtain the photocatalytic superhydrophobic coating. 2. the preparation method of photocatalytic superhydrophobic coating according to claim 1, is characterized in that, described substrate is glass, copper flake or aluminum flake. 3. The preparation method of photocatalytic superhydrophobic coating according to claim 1, characterized in that, in step (1), the heating temperature is 75-85°C, and the heating time is 4-6min. 4. according to the preparation method of photocatalytic superhydrophobic coating described in claim 1, it is characterized in that, in step (2), the mass volume ratio of bismuth nitrate pentahydrate and ethylene glycol is 1.46g:35-45ml, potassium iodide and The mass volume ratio of ethylene glycol is 0.5g:35-45ml. 5. The preparation method of photocatalytic superhydrophobic coating according to claim 1, characterized in that, the heating temperature in step (2) is 140-160°C, and the reaction time is 12-24h. 6. according to the preparation method of photocatalytic superhydrophobic coating described in claim 1, it is characterized in that, in step (3), the mass volume ratio of sodium molybdate and deionized water is 0.015-0.045g: 60ml, thioethyl The molar ratio of amide to sodium molybdate is 1:3, and the mass ratio of sodium molybdate to bismuth oxyiodide is 0.015-0.045:1. 7. according to the preparation method of the described photocatalytic superhydrophobic coating of claim 1, it is characterized in that the quality of cadmium chloride hydrate, cetyltrimethylammonium bromide and water in solution A in step (4) The volume ratio is 2.2841g:0.05-0.1g:20ml, and the mass-volume ratio of sodium sulfide nonahydrate, cetyltrimethylammonium bromide and water in solution B is 2.4018g:0.05-0.1g:20ml. 8. The preparation method of photocatalytic superhydrophobic coating according to claim 1, characterized in that, in step (4), the heating temperature is 120-180°C, the reaction time is 4-12h, and the drying temperature is 55-65°C , drying time is 10-14h. 9. according to the preparation method of photocatalytic superhydrophobic coating described in claim 1, it is characterized in that, in step (5), the mass ratio of hexane and dehydrated alcohol is 1:2, polydimethylsiloxane and The mass ratio of curing agent is 10:1. 10. the preparation method of photocatalytic superhydrophobic coating according to claim 1 is characterized in that, in step (5), the mass ratio of polydimethylsiloxane and BiOI/MoS ₂ /CdS is 4:1- 4.