A photocatalytic nanocomposite, a preparation method and application thereof

Abstract

The application discloses a kind of photocatalytic nanocomposite and its preparation method and application, belong to nanocomposite technical field, first synthesis CuInS2 quantum dot powder, a layer of carbon is covered on the surface of CuInS2 quantum dot powder, then amino is introduced by silane coupling agent modification, then modified carbon composite CuInS2 quantum dot powder is loaded on tubular carbon nitride powder formed.The tubular structure of tubular carbon nitride powder is conducive to CuInS2 quantum dot dispersion on its surface or inside, so that the active site of CuInS2 quantum dot powder is fully exposed, the band gap energy of CuInS2 quantum dot powder is about 1.53eV, when being irradiated, electron and hole pair can be generated, can promote the separation of photoinduced electron and hole to improve the activity of catalyst, and the dense carbon layer on CuInS2 quantum dot powder can form physical barrier to prevent peroxide from directly contacting with sulfur ion.

Description

Technical Field

[0001] This invention belongs to the field of nanocomposite materials technology, specifically a photocatalytic nanocomposite material, its preparation method, and its application. Background Technology

[0002] Quantum dots offer a novel approach to the design of photocatalytic nanocomposites due to their size-dependent quantum confinement effect and wide spectral tunability (from visible to near-infrared). Traditional photocatalysts are limited by wide band gaps and can only utilize ultraviolet light, while quantum dots (such as CdSe and CsPbBr3) can extend the absorption edge to over 650 nm through size control, significantly improving the utilization rate of sunlight. In addition, the high exciton generation efficiency and multiexciton effect of quantum dots can greatly enhance photocatalytic activity.

[0003] Chinese invention patent application CN111450852B discloses a method for synthesizing a nickel-cobalt bimetallic hydroxide / copper indium sulfide / tungsten oxide nanocomposite material and its application in water splitting for hydrogen production. The method involves preparing ethanol solutions of NiCo-LDH, CuInS2, and WO3, and then sequentially adding the CuInS2 and WO3 ethanol solutions dropwise to the NiCo-LDH ethanol solution. After stirring for 4–16 hours, the mixture is centrifuged and vacuum dried at 50–110°C for 2–12 hours to obtain the final product. This method utilizes hydrothermal, calcination, and mechanical composite methods to prepare the NiCo-LDH / CuInS2 / WO3 nanocomposite material, which exhibits excellent photocatalytic activity, strong light absorption capacity, and good stability. It can be applied to photocatalytic water splitting for hydrogen production. The raw materials used are inexpensive and readily available, the process is simple, the experimental results are reproducible, and it is also environmentally friendly. The construction of Z-type heterojunctions shows great potential in solar-to-hydrogen energy conversion applications.

[0004] However, when copper indium sulfide nanocomposites catalyze the degradation of organic matter under light conditions, the reaction system often contains oxidizing substances such as peroxides, which may oxidize sulfur ions to elemental sulfur, leading to the loss of sulfur ions from copper indium sulfide, destroying the crystal structure of copper indium sulfide, and causing a decrease in the catalytic activity of the nanocomposites. Summary of the Invention

[0005] The purpose of this invention is to provide a photocatalytic nanocomposite material, its preparation method and application. By coating a carbon layer on the surface of CuInS2 quantum dot powder, then modifying it to introduce amino groups, and then chemically combining it with tubular carbon nitride powder, the problem of peroxides easily destroying the crystal structure of copper indium sulfide in organic degradation systems is solved, thereby improving the catalytic efficiency in organic synthesis systems.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for preparing a photocatalytic nanocomposite material includes the following steps:

[0008] Step 1: First, CuInS2 quantum dot powder is prepared using copper nitrate trihydrate as the copper source and indium nitrate tetrahydrate as the indium source. Then, the CuInS2 quantum dot powder is coated with carbon to obtain carbon composite CuInS2 quantum dot powder.

[0009] Step 2: The carbon composite CuInS2 quantum dot powder is modified with γ-aminopropyltriethoxysilane to obtain amino-modified carbon composite CuInS2 quantum dot powder. The modified carbon composite CuInS2 quantum dot powder is then loaded onto tubular carbon nitride powder to obtain a photocatalytic nanocomposite material.

[0010] Furthermore, CuInS2 quantum dot powder is prepared via the following steps:

[0011] Copper nitrate trihydrate, indium nitrate tetrahydrate, 3-mercaptopropionic acid, deionized water, and sodium sulfide nonahydrate were added to a reaction vessel. The pH was adjusted to 10 with sodium hydroxide solution. The reaction was carried out under nitrogen protection and at 150-160℃ for 10-12 hours. After cooling to room temperature, the mixture was filtered, washed, and dried to obtain CuInS2 quantum dot powder.

[0012] Furthermore, the ratio of copper nitrate trihydrate, indium nitrate tetrahydrate, 3-mercaptopropionic acid, deionized water, and sodium sulfide nonahydrate is: 12-15g: 37-45g: 127-150g: 1-2L: 190-220g.

[0013] Furthermore, the carbon composite CuInS2 quantum dot powder was prepared via the following steps:

[0014] CuInS2 quantum dot powder, tris(hydroxymethyl)aminomethane, and deionized water were added to a reaction vessel and ultrasonically dispersed. A 4-10 g / L aqueous solution of dopamine hydrochloride was then added dropwise at 20-25 °C and 300-500 r / min. The reaction was carried out for 20-22 h, filtered, washed, lyophilized, and then heat-treated at 500-520 °C for 2-3 h under argon protection to obtain carbon composite CuInS2 quantum dot powder.

[0015] Furthermore, the ratio of CuInS2 quantum dot powder, tris(hydroxymethyl)aminomethane, deionized water, and dopamine hydrochloride aqueous solution is 10-15g: 6-8g: 10-12L: 1-1.5L.

[0016] Furthermore, the photocatalytic nanocomposite material is prepared through the following steps:

[0017] Tubular carbon nitride powder, deionized water, triethylamine, and an aqueous solution of modified carbon composite CuInS2 quantum dot powder with a concentration of 0.083-0.12 mg / mL were added to a reaction vessel and mixed evenly. Then, a hydrochloric acid solution with a concentration of 0.1 mol / L was added, and the mixture was allowed to stand for 2-3 hours. After filtration, washing, and drying, the photocatalytic nanocomposite material was obtained.

[0018] Furthermore, the ratio of tubular carbon nitride powder, deionized water, triethylamine, modified carbon composite CuInS2 quantum dot powder aqueous solution and hydrochloric acid solution is 5-8g: 2-2.2L: 30-35mL: 500-600mL: 1.2-1.5L.

[0019] Furthermore, the tubular carbon nitride powder is prepared by the following steps:

[0020] Melamine, trithiocyanate, deionized water and methanol are added to a reaction vessel and ultrasonically treated. The mixture is reacted at 20-25℃ and 300-600 r / min for 12-14 h. After filtration, washing and drying, the mixture is placed in a tube furnace and heated to 500-520℃ at a rate of 4.6℃ / min under nitrogen atmosphere. The temperature is held for 2-3 h and then naturally cooled to room temperature. The mixture is then ground to obtain tubular carbon nitride powder.

[0021] Furthermore, the ratio of melamine, trithiocyanate, deionized water, and methanol is 5-10g: 7-15g: 1.2-1.5L: 200-300mL.

[0022] Application of a photocatalytic nanocomposite material as a photocatalyst in the degradation of organic matter.

[0023] The beneficial effects of this invention are:

[0024] 1. The photocatalytic nanocomposite material in this invention is formed by first synthesizing CuInS2 quantum dot powder, coating the surface of CuInS2 quantum dot powder with a layer of carbon, then introducing amino groups through modification with a silane coupling agent, and finally loading the modified carbon composite CuInS2 quantum dot powder onto tubular carbon nitride powder. The tubular structure of the carbon nitride powder provides a high surface area, which is beneficial for the dispersion of CuInS2 quantum dots on or inside the powder, thus fully exposing the active sites of the CuInS2 quantum dot powder. The band gap energy of the CuInS2 quantum dot powder is about 1.53 eV, exhibiting broad absorption from ultraviolet to visible light. When exposed to light, it generates electron-hole pairs, which can promote the separation of photogenerated electrons and holes, thereby improving the activity of the catalyst. The dense carbon layer coating on the CuInS2 quantum dot powder forms a physical barrier, preventing peroxides from directly contacting sulfur ions. At the same time, the carbon layer can rapidly transfer photogenerated electrons, preventing them from accumulating on the sulfur ion surface and inhibiting the oxidation of sulfur ions. This ensures that the crystal structure of copper indium sulfide is not destroyed during the photocatalytic process, improving the reusability of the photocatalytic nanocomposite material.

[0025] 2. In this invention, the carbon composite CuInS2 quantum dot powder is first synthesized using copper nitrate trihydrate as the copper source, indium nitrate tetrahydrate as the indium source, sodium sulfide as the sulfur source, and 3-mercaptopropionic acid as a modifier. The mercapto groups in 3-mercaptopropionic acid dissociate and form metal-S bonds on the surface of CuInS2 quantum dots, forming a mesoporous structure, which improves the separation and transfer efficiency of photogenerated carriers in the photocatalyst nanocomposite material, thereby improving the catalytic activity of the photocatalyst. Then, dopamine hydrochloride is used as a carbon source to polymerize and form polydopamine hydrochloride. After high-temperature calcination, a dense carbon layer is formed on the surface of CuInS2 quantum dots, maintaining the catalytic activity of the photocatalyst nanocomposite material. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1: This example provides a photocatalytic nanocomposite material, prepared through the following steps:

[0028] S1: 13g of copper nitrate trihydrate, 41g of indium nitrate tetrahydrate, 138g of 3-mercaptopropionic acid as a modifier, and 1.5L of deionized water were added to a reaction vessel and mixed evenly at 22℃ and 400r / min. Then, 205g of sodium sulfide nonahydrate was added, and the pH was adjusted to 10 with sodium hydroxide solution. The reaction was carried out under nitrogen protection and at 155℃ for 11h. After cooling to room temperature, the mixture was centrifuged and filtered. The filter cake was washed four times with ethanol and deionized water, and then vacuum dried to constant weight to obtain CuInS2 quantum dot powder.

[0029] S2: 12.5g CuInS2 quantum dot powder, 7g tris(hydroxymethyl)aminomethane and 11L deionized water were added to a reaction vessel and ultrasonically dispersed for 25min. 1.25L of 7g / L dopamine hydrochloride aqueous solution was added dropwise to the reaction vessel at 22℃ and 400r / min. The reaction was carried out for 21h, filtered, and the filter cake was washed 4 times with deionized water, lyophilized, and heat-treated at 510℃ for 2.5h under argon protection to obtain carbon composite CuInS2 quantum dot powder.

[0030] S3: Add 7.5g melamine, 11g trithiocyanate, 1.35L deionized water and 250mL methanol to a reaction vessel, sonicate for 15min, react at 22℃ and 450r / min for 13h, filter, wash the filter cake three times with deionized water, dry at 75℃ for 10h, then place it in a tube furnace, heat to 510℃ at a rate of 4.6℃ / min under nitrogen, hold at 510℃ for 2.5h, cool naturally to room temperature, grind to obtain tubular carbon nitride powder.

[0031] S4: 7.5g of carbon composite CuInS2 quantum dot powder and 11L of deionized water were added to a reaction vessel and ultrasonically dispersed for 2.5h. Then, 35mL of silane coupling agent γ-aminopropyltriethoxysilane was added, and the reaction was carried out at 75℃ and 650r / min for 4.5h. γ-aminopropyltriethoxysilane was grafted onto the carbon composite CuInS2 quantum dot powder to form Si-OC bonds. The mixture was centrifuged and filtered. The filter cake was washed with deionized water until neutral and then vacuum dried at 65℃ for 25h to obtain modified carbon composite CuInS2 quantum dot powder.

[0032] S5: 7.5g of tubular carbon nitride powder and 2.1L of deionized water were added to the reaction vessel and ultrasonically dispersed for 35min. 32mL of triethylamine was added at 650r / min. Then, 55mg of modified carbon composite CuInS2 quantum dot powder and 550mL of deionized water were mixed evenly and added to the reaction vessel. 1.3L of 0.1mol / L hydrochloric acid solution was added, and the mixture was allowed to stand for 2.5h. The amino groups on the tubular carbon nitride powder and the modified carbon composite CuInS2 quantum dot powder formed hydrogen bonds and bonded together. The mixture was centrifuged and filtered. The filter cake was washed with deionized water until neutral and dried at 65℃ to constant weight to obtain the photocatalytic nanocomposite material.

[0033] Example 2: This example provides a photocatalytic nanocomposite material, prepared through the following steps:

[0034] S1: 12g of copper nitrate trihydrate, 37g of indium nitrate tetrahydrate, 127g of 3-mercaptopropionic acid as a modifier, and 1L of deionized water were added to a reaction vessel and mixed evenly at 20℃ and 300r / min. Then, 190g of sodium sulfide nonahydrate was added, and the pH was adjusted to 10 with sodium hydroxide solution. The reaction was carried out under nitrogen protection and at 150℃ for 10h. After cooling to room temperature, the mixture was centrifuged and filtered. The filter cake was washed three times with ethanol and deionized water, and then vacuum dried to constant weight to obtain CuInS2 quantum dot powder.

[0035] S2: 10g CuInS2 quantum dot powder, 6g tris(hydroxymethyl)aminomethane and 10L deionized water were added to a reaction vessel and ultrasonically dispersed for 20min. 1L of 4g / L dopamine hydrochloride aqueous solution was added dropwise to the reaction vessel at 20℃ and 300r / min. The reaction was carried out for 20h, filtered, the filter cake was washed three times with deionized water, freeze-dried, and heat-treated at 500℃ for 2h under argon protection to obtain carbon composite CuInS2 quantum dot powder.

[0036] S3: Add 5g melamine, 7g trithiocyanate, 1.2L deionized water and 200mL methanol to a reaction vessel, sonicate for 10min, react at 20℃ and 300r / min for 12h, filter, wash the filter cake twice with deionized water, dry at 70℃ for 8h, then place it in a tube furnace, heat to 500℃ at a rate of 4.6℃ / min under nitrogen, hold for 2h, cool naturally to room temperature, grind to obtain tubular carbon nitride powder.

[0037] S4: Add 5g of carbon composite CuInS2 quantum dot powder and 10L of deionized water to a reaction vessel, and ultrasonically disperse for 2h. Then add 30mL of silane coupling agent γ-aminopropyltriethoxysilane, and react for 4h at 70℃ and 500r / min to graft γ-aminopropyltriethoxysilane onto the carbon composite CuInS2 quantum dot powder to form Si-OC bonds. Centrifuge and filter, wash the filter cake with deionized water until neutral, and vacuum dry at 60℃ for 24h to obtain modified carbon composite CuInS2 quantum dot powder.

[0038] S5: Add 5g of tubular carbon nitride powder and 2L of deionized water to a reaction vessel and ultrasonically disperse for 30min. Add 30mL of triethylamine at 500r / min. Then, mix 50mg of modified carbon composite CuInS2 quantum dot powder and 500mL of deionized water evenly and add it to the reaction vessel. Add 1.2L of 0.1mol / L hydrochloric acid solution and let it stand for 2h. The amino groups on the tubular carbon nitride powder and the modified carbon composite CuInS2 quantum dot powder form hydrogen bonds and combine together. Centrifuge and filter. Wash the filter cake with deionized water until it is neutral and dry it at 60℃ to constant weight to obtain the photocatalytic nanocomposite material.

[0039] Example 3: This example provides a photocatalytic nanocomposite material, prepared through the following steps:

[0040] S1: 15g of copper nitrate trihydrate, 45g of indium nitrate tetrahydrate, 150g of 3-mercaptopropionic acid as a modifier, and 2L of deionized water were added to a reaction vessel and mixed evenly at 25℃ and 500r / min. Then, 220g of sodium sulfide nonahydrate was added, and the pH was adjusted to 10 with sodium hydroxide solution. The reaction was carried out under nitrogen protection and at 160℃ for 12h. After cooling to room temperature, the mixture was centrifuged and filtered. The filter cake was washed 5 times with ethanol and deionized water, respectively, and then vacuum dried to constant weight to obtain CuInS2 quantum dot powder.

[0041] S2: 15g CuInS2 quantum dot powder, 8g tris(hydroxymethyl)aminomethane and 12L deionized water were added to a reaction vessel and ultrasonically dispersed for 30min. 1.5L of 10g / L dopamine hydrochloride aqueous solution was added dropwise to the reaction vessel at 25℃ and 500r / min. The reaction was carried out for 22h, filtered, and the filter cake was washed 5 times with deionized water, freeze-dried, and heat-treated at 520℃ for 3h under argon protection to obtain carbon composite CuInS2 quantum dot powder.

[0042] S3: Add 10g melamine, 15g trithiocyanate, 1.5L deionized water and 300mL methanol to a reaction vessel, sonicate for 20min, react at 25℃ and 600r / min for 14h, filter, wash the filter cake 5 times with deionized water, dry at 80℃ for 12h, then place it in a tube furnace, heat to 520℃ at a rate of 4.6℃ / min under nitrogen, hold for 3h, cool naturally to room temperature, grind to obtain tubular carbon nitride powder.

[0043] S4: Add 10g of carbon composite CuInS2 quantum dot powder and 12L of deionized water to a reaction vessel, and ultrasonically disperse for 3h. Then add 40mL of silane coupling agent γ-aminopropyltriethoxysilane, and react for 5h at 80℃ and 800r / min to graft γ-aminopropyltriethoxysilane onto the carbon composite CuInS2 quantum dot powder to form Si-OC bonds. Centrifuge and filter, wash the filter cake with deionized water until neutral, and vacuum dry at 70℃ for 26h to obtain modified carbon composite CuInS2 quantum dot powder.

[0044] S5: Add 8g of tubular carbon nitride powder and 2.2L of deionized water to a reaction vessel and ultrasonically disperse for 40min. Add 35mL of triethylamine at 800r / min. Then, mix 60mg of modified carbon composite CuInS2 quantum dot powder and 600mL of deionized water evenly and add it to the reaction vessel. Add 1.5L of 0.1mol / L hydrochloric acid solution and let it stand for 3h. The amino groups on the tubular carbon nitride powder and the modified carbon composite CuInS2 quantum dot powder form hydrogen bonds and combine together. Centrifuge and filter. Wash the filter cake with deionized water until it is neutral and dry it at 70℃ to constant weight to obtain the photocatalytic nanocomposite material.

[0045] Comparative Example 1: Based on Example 1, in step S5, commercially available carbon nitride powder (model PA28413, purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd.) was used instead of tubular carbon nitride powder, while the other steps remained unchanged, and photocatalytic nanocomposite material was prepared.

[0046] Comparative Example 2: Based on Example 1, in step S5, the CuInS2 quantum dot powder prepared in step S1 was used instead of the modified carbon composite CuInS2 quantum dot powder, while the other steps remained unchanged, and a photocatalytic nanocomposite material was prepared.

[0047] Comparative Example 3: Based on Example 1, in step S5, the modified carbon composite CuInS2 quantum dot powder was replaced with the carbon composite CuInS2 quantum dot powder prepared in step S2, while the other steps remained unchanged, and a photocatalytic nanocomposite material was prepared.

[0048] The photocatalytic performance of the photocatalytic nanocomposites from Examples 1-3 and Comparative Examples 1-3 was studied. A 300W xenon lamp was used as a simulated light source to test the photocatalytic efficiency of the prepared photocatalytic nanocomposites under visible light irradiation. Tetracycline hydrochloride at a concentration of 10 mg / L was selected as the reaction substrate. 100 mL of the solution was placed in a beaker, and the pH was adjusted to 3 with hydrogen peroxide solution. Then, 30 mg of the corresponding photocatalytic nanocomposite was added to the corresponding beaker. The solution was placed in the dark for 30 min for adsorption, and then irradiated under a xenon lamp for 120 min to study its photocatalytic performance. After the reaction was completed, CuInS2 was separated from the reaction mixture by centrifugation and filtration, washed several times with water and ethanol, dried, and reused in subsequent catalytic cycles. The number of reuses was recorded as long as the photocatalytic efficiency did not decrease. The experiment was set up in three groups, and the average value of the three groups was taken. The experimental results are shown in the table below.

[0049] Table 1. Overview of the catalytic effects of photocatalytic nanocomposite materials

[0050]

[0051] As shown in Table 1, the degradation efficiency in Examples 1-3 is higher than that in Comparative Examples 1-3, with Comparative Example 1 having the lowest degradation efficiency. In step S5 of Comparative Example 1, commercially available carbon nitride powder was used instead of tubular carbon nitride powder, indicating that the tubular structure of the tubular carbon nitride powder is beneficial to improving the degradation efficiency of the photocatalytic nanocomposite material. This may be because the tubular structure exposes more active sites. In step S5 of Comparative Example 2, CuInS2 quantum dot powder prepared in step S1 was used instead of modified carbon composite CuInS2 quantum dot powder, and the degradation efficiency was slightly lower, indicating that carbon-coated CuInS2 quantum dot powder can also improve the degradation efficiency of the photocatalytic nanocomposite material.

[0052] The number of reuses in Examples 1-3 was higher than that in Comparative Examples 1-3, while the number of reuses in Comparative Example 2 was the lowest. In step S5 of Comparative Example 2, the CuInS2 quantum dot powder prepared in step S1 was used instead of the modified carbon composite CuInS2 quantum dot powder, indicating that carbon coating can increase the number of reuses and make the crystal structure more stable. The number of reuses in Comparative Example 3 was slightly lower. In step S5 of Comparative Example 3, the carbon composite CuInS2 quantum dot powder prepared in step S2 was used instead of the modified carbon composite CuInS2 quantum dot powder, indicating that modification can increase the bonding force with the tubular carbon nitride powder and increase the number of reuses.

[0053] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0054] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for preparing a photocatalytic nanocomposite material, characterized in that, Includes the following steps: Step 1: First, CuInS2 quantum dot powder is prepared using copper nitrate trihydrate as the copper source and indium nitrate tetrahydrate as the indium source. Then, the CuInS2 quantum dot powder is coated with carbon to obtain carbon composite CuInS2 quantum dot powder. Step 2: The carbon composite CuInS2 quantum dot powder is modified with γ-aminopropyltriethoxysilane to obtain amino-modified carbon composite CuInS2 quantum dot powder. The modified carbon composite CuInS2 quantum dot powder is then loaded onto tubular carbon nitride powder to obtain a photocatalytic nanocomposite material.

2. The method for preparing a photocatalytic nanocomposite material according to claim 1, characterized in that, The CuInS2 quantum dot powder mentioned in step one is prepared through the following steps: Copper nitrate trihydrate, indium nitrate tetrahydrate, 3-mercaptopropionic acid, deionized water, and sodium sulfide nonahydrate were added to a reaction vessel. The pH was adjusted to 10 with sodium hydroxide solution. The reaction was carried out under nitrogen protection and at 150-160℃ for 10-12 hours. After cooling to room temperature, the mixture was filtered, washed, and dried to obtain CuInS2 quantum dot powder.

3. The method for preparing a photocatalytic nanocomposite material according to claim 2, characterized in that, The ratio of copper nitrate trihydrate, indium nitrate tetrahydrate, 3-mercaptopropionic acid, deionized water, and sodium sulfide nonahydrate is: 12-15g: 37-45g: 127-150g: 1-2L: 190-220g.

4. The method for preparing a photocatalytic nanocomposite material according to claim 1, characterized in that, The carbon composite CuInS2 quantum dot powder mentioned in step one is prepared through the following steps: CuInS2 quantum dot powder, tris(hydroxymethyl)aminomethane, and deionized water were added to a reaction vessel and ultrasonically dispersed. A 4-10 g / L aqueous solution of dopamine hydrochloride was then added dropwise at 20-25 °C and 300-500 r / min. The reaction was carried out for 20-22 h, filtered, washed, lyophilized, and then heat-treated at 500-520 °C for 2-3 h under argon protection to obtain carbon composite CuInS2 quantum dot powder.

5. The method for preparing a photocatalytic nanocomposite material according to claim 4, characterized in that, The ratio of CuInS2 quantum dot powder, tris(hydroxymethyl)aminomethane, deionized water, and dopamine hydrochloride aqueous solution is 10-15g: 6-8g: 10-12L: 1-1.5L.

6. The method for preparing a photocatalytic nanocomposite material according to claim 1, characterized in that, The photocatalytic nanocomposite material described in step two is prepared through the following steps: Tubular carbon nitride powder, deionized water, triethylamine, and an aqueous solution of modified carbon composite CuInS2 quantum dot powder with a concentration of 0.083-0.12 mg / mL were added to a reaction vessel and mixed evenly. Then, a hydrochloric acid solution with a concentration of 0.1 mol / L was added, and the mixture was allowed to stand for 2-3 hours. After filtration, washing, and drying, the photocatalytic nanocomposite material was obtained.

7. The method for preparing a photocatalytic nanocomposite material according to claim 6, characterized in that, The ratio of the tubular carbon nitride powder, deionized water, triethylamine, modified carbon composite CuInS2 quantum dot powder aqueous solution and hydrochloric acid solution is 5-8g: 2-2.2L: 30-35mL: 500-600mL: 1.2-1.5L.

8. The method for preparing a photocatalytic nanocomposite material according to claim 7, characterized in that, The tubular carbon nitride powder is prepared by the following steps: Melamine, trithiocyanate, deionized water and methanol are added to a reaction vessel and ultrasonically treated. The reaction is carried out at 20-25℃ and 300-600 r / min for 12-14 h. The mixture is then filtered, washed, dried and placed in a tube furnace. The temperature is raised to 500-520℃ at a rate of 4.6℃ / min under nitrogen atmosphere and held for 2-3 h. The mixture is then allowed to cool naturally to room temperature and ground to obtain tubular carbon nitride powder. The ratio of melamine, trithiocyanate, deionized water and methanol is 5-10g: 7-15g: 1.2-1.5L: 200-300mL.

9. A photocatalytic nanocomposite material, characterized in that, It is prepared by the method of any one of claims 1-8 for preparing a photocatalytic nanocomposite material.

10. The application of the photocatalytic nanocomposite material according to claim 9 as a photocatalyst in the degradation of organic matter.

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