A carbon nitride nanosheet composite material, a preparation method therefor and applications thereof

Abstract

The application relates to a carbon nitride nanosheet composite material and a preparation method and application thereof, and the preparation method comprises the following steps: uniformly mixing carbon quantum dot precursors with mixed solvents, carrying out first hydrothermal reaction, and obtaining carbon quantum dots after cooling; uniformly mixing carbon nitride precursors with the carbon quantum dots, carrying out second hydrothermal reaction, and obtaining a carbon nitride nanosheet composite material intermediate after cooling, cleaning and drying; sufficiently drying and grinding the carbon nitride nanosheet composite material intermediate, calcining under an inert atmosphere, and obtaining the carbon nitride nanosheet composite material after cooling. Compared with the prior art, the carbon quantum dot and carbon nitride composite nanosheet material is prepared through a hydrothermal calcination process, and by adjusting reaction conditions, controlling the feeding ratio between raw materials, the heating rate of calcination, the holding temperature, the reaction time and the like, the carbon quantum dot and carbon nitride nanosheet composite photocatalytic material with excellent photocatalytic performance is prepared.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photocatalysis new materials, in particular to a carbon nitride nanosheet composite material and a preparation method and application thereof. BACKGROUND

[0002] With the development of human society, more and more convenient social and living conditions, efficient social operation speed and higher and higher degree of industrialization make the living standard of human beings improve continuously, which causes the mutual restriction of resources and environment, and makes the global ecological environment protection work still have a long way to go. In order to realize the sustainable development problem proposed by the environment and energy crisis problem, it is necessary to realize the coordination and unity of society, economy, energy, resources and environment, and to create a harmonious production and living environment for people. Energy is an important material guarantee for realizing sustainable development, and only through the reasonable development and utilization of energy, the emission path of energy and the optimization of energy structure, can the green development of energy be realized. As the main source of earth energy, solar energy is a kind of renewable, abundant and clean energy. It provides a clear direction for the energy problem faced by human beings at present. The photocatalysis technology can directly utilize solar energy to react at room temperature, for example, using photocatalysis technology to decompose water to obtain renewable, pollution-free clean energy, degrading industrial wastewater by photocatalysis and reducing carbon dioxide to fuel by photocatalysis, which has good application prospect in the fields of energy preparation and environmental protection.

[0003] At present, the catalysts studied more are classified according to the atomic arrangement, mainly including three categories: crystalline catalyst, quasi-crystalline catalyst and amorphous catalyst. There are many common photocatalytic materials, such as TiO2, Bi2WO6 and CdS, etc., which can all respond to visible light. Carbon nitride, as an organic two-dimensional polymer semiconductor, only contains C and N elements, with a band gap of 2.7eV and visible light activity (λ<460nm). In addition, its rich precursor source, simple preparation method and stable physical and chemical properties have attracted more and more attention. However, due to the problems of small specific surface area, serious photo-generated carrier recombination and weak visible light response of existing catalyst materials, the utilization rate of solar energy is very low, and the photocatalytic activity is not high. Therefore, it is very important to try different modification methods to explore and construct high-efficiency visible light response photocatalytic materials, and to study the synthesis method and photocatalytic mechanism of photocatalytic materials, which is also the concern of many scientific and technical workers.

[0004] At present, many traditional modification methods such as regulating the morphology of carbon nitride to improve the specific surface area of the sample, element doping to expand the light response range and carrier migration, using heterojunction to promote the separation of photo-generated carriers and inhibit the recombination, introducing noble metal nanoparticles to expand the light absorption range, etc. are applied to improve the photocatalytic activity of carbon nitride, and certain results have been achieved. However, due to the high recombination rate of photo-generated electron-hole pairs and poor stability, the photocatalytic efficiency of carbon nitride still cannot meet the requirements of practical application. Therefore, finding new modification methods to improve the separation efficiency of electron-hole pairs and the light response range, and enhancing the photocatalytic performance, is still a research hotspot in recent years.

[0005] CN111841599A discloses a carbon quantum dot doped carbon nitride composite nanomaterial with photocatalytic antibacterial performance and a preparation method and application thereof. The method comprises the following steps: preparing two crucibles with different sizes, loading a precursor for preparing carbon quantum dots (CQDs) into a large crucible, and loading a precursor for preparing carbon nitride (CN) into a small crucible. The small crucible is loaded into the large crucible, covered and then placed in a muffle furnace for calcination, and finally a CQDs\CN composite photocatalytic antibacterial material is obtained. However, the method releases toxic ammonia gas during the preparation process. SUMMARY

[0006] The purpose of the present application is to overcome the defects of the prior art and provide a carbon nitride nanosheet composite material, a preparation method and application thereof. A new strategy of carbon quantum dot assisted preparation of carbon nitride nanosheet composite photocatalytic material is adopted. The carbon quantum dot hydrothermal-calcined carbon nitride nanosheet composite material does not produce other toxic gases, and also enhances the strong response to visible light, effectively slows down the recombination rate of electrons and holes on the material surface, and the material shows strong response to visible light. The preparation process is environmentally friendly, and the photocatalytic hydrogen production performance of the material is obviously improved compared with similar carbon nitride materials. The carbon quantum dot and carbon nitride precursor are hydrothermally calcined to prepare the photocatalytic material, and the reaction conditions are adjusted, the feeding ratio of the raw materials, the calcination heating rate, the holding temperature and the reaction time are controlled, and the photocatalytic material with excellent photocatalytic performance is prepared. In addition, the preparation method is simple in operation, the raw materials are cheap, the reaction time is short, and it can be applied to large-scale production.

[0007] The purpose of the present application can be achieved by the following technical solutions:

[0008] The first purpose of the present application is to provide a preparation method of a carbon nitride nanosheet composite material, which is a carbon quantum dot assisted preparation method, and the preparation method comprises the following steps:

[0009] S1, a certain amount of carbon quantum dot precursor is mixed with a mixed solvent uniformly, then is transferred into a hydrothermal reactor, and is subjected to a first hydrothermal reaction at a certain temperature, and carbon quantum dots are obtained after cooling;

[0010] S2, a certain amount of carbon nitride precursor is mixed with the carbon quantum dots obtained in step S1 uniformly, then is transferred into a hydrothermal reactor, and is subjected to a second hydrothermal reaction at a certain temperature, and a carbon nitride nanosheet composite intermediate is obtained after cooling, washing and drying;

[0011] S3, the carbon nitride nanosheet composite intermediate obtained in step S2 is dried and ground sufficiently, then is calcined in an inert atmosphere, and the carbon nitride nanosheet composite is obtained after cooling.

[0012] Further, in step S1, the carbon quantum dot precursor is selected from one or more of o-phenylenedinitrile, 2,3-diamino maleonitrile, 2-cyanobenzoic acid, colliding, fumaronitrile, o-phenylenediamine and the like.

[0013] Further, in step S1, the mixed solvent is selected from one or more of acetonitrile, acetone, methanol, ethanol, toluene, water and the like.

[0014] Further, in step S2, the carbon nitride precursor is selected from one or more of monocyanoamine, dicyanoamine, ammonium thiocyanate, barbituric acid, melamine, thiourea, urea and the like.

[0015] Further, in step S2, the mass ratio of the carbon quantum dots to the carbon nitride precursor is 0.004 to 0.04.

[0016] Further, in step S1, the reaction temperature of the first hydrothermal reaction is 100 to 200 DEG C, the reaction time is 1 to 20 h, and the pressure is 0.1 to 2 MPa.

[0017] Further, the reaction temperature and the reaction time of the second hydrothermal reaction are consistent with the conditions of the first hydrothermal reaction, that is, in step S2, the reaction temperature of the second hydrothermal reaction is 100 to 200 DEG C, the reaction time is 1 to 20 h, and the pressure is 0.1 to 2 MPa.

[0018] Further, in step S2, the washing is specifically: washing with distilled water and anhydrous ethanol alternately for 5 times; and the drying is specifically: drying at 60 DEG C for 12 h.

[0019] Further, in step S3, the calcination temperature of the calcination is 450 to 700 DEG C, the heating rate is 1 to 10 DEG C / min, and the holding time is 1 to 12 h.

[0020] Further, in step S3, the inert gas is selected from one or a mixture of at least two of nitrogen, helium and argon.

[0021] Further, in step S3, after the calcination and cooling, sub-steps of washing, drying and grinding are further included; the washing is specifically: washing 1-3 times alternately with distilled water and anhydrous ethanol; the drying is specifically: drying at 50-100 DEG C for 2-12 hours.

[0022] A second object of the present application is to provide a carbon nitride nanosheet composite material obtained by the above preparation method.

[0023] A third object of the present application is to provide a carbon nitride nanosheet composite material obtained by the above preparation method, which is applied to the field of photocatalysis.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] 1) The preparation method of the carbon nitride nanosheet composite material provided by the present application, by combining hydrothermal polymerization and high-temperature calcination, a carbon nitride nanosheet composite photocatalytic material with large specific surface area is prepared, the preparation process is simple and controllable, and is conducive to mass production and popularization.

[0026] 2) The preparation method of the carbon nitride nanosheet composite material provided by the present application adopts a carbon quantum dot assisted synthesis method, and the prepared carbon nitride nanosheet composite material can effectively solve the problems of small specific surface area of bulk carbon nitride material, low utilization rate of photo-generated carriers, and small visible light response range, thereby improving the photocatalytic efficiency of the carbon nitride nanosheet composite material (the photocatalytic hydrogen production efficiency can reach 65000 μmol g -1 h -1 ).

[0027] 3) The preparation method of the carbon nitride nanosheet composite material provided by the present application has a simple preparation process, uses cheap and easily available raw materials, is easy to operate, and has a wide source of raw materials, and is suitable for popularization and application.

[0028] 4) The preparation method of the carbon nitride nanosheet composite material provided by the present application effectively slows down the recombination rate of electrons and holes on the material surface, the material shows strong response ability to visible light, and the preparation process is environmentally friendly, compared with similar carbon nitride materials, the photocatalytic hydrogen production performance of the prepared carbon nitride nanosheet composite material is obviously improved.

[0029] 5) The preparation method of the carbon nitride nanosheet composite material provided by the application effectively slows down the recombination rate of electrons and holes on the surface of the material, the material exhibits strong response ability to visible light, and the preparation process is environmentally friendly, compared with similar carbon nitride materials, the photocatalytic hydrogen production performance of the prepared carbon nitride nanosheet composite material is obviously improved.

[0030] 6) The carbon nitride nanosheet composite material provided by the application can be used in the field of photocatalysis. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The flow chart of the preparation method of the carbon nitride nanosheet composite material in the application.

[0032] Figure 2 The TEM images of the carbon quantum dots (CDs-25) and the carbon nitride nanosheet composite material (CDs-25 / CN) in Example 2 of the application, wherein (a) is the carbon quantum dots, and (b) is the carbon nitride nanosheet composite material.

[0033] Figure 3 The atomic force microscope images of the carbon quantum dots and the carbon nitride nanosheet composite material in Example 2 of the application, wherein (a) is the carbon quantum dots, and (b) is the carbon nitride nanosheet composite material.

[0034] Figure 4 The element Mapping image of the carbon nitride nanosheet composite material in Example 2 of the application.

[0035] Figure 5 The nitrogen adsorption / desorption isotherm of the carbon quantum dots and the carbon nitride nanosheet composite material in Example 2 of the application, and the pore size distribution graph is inserted.

[0036] Figure 6 The photocatalytic hydrogen production performance comparison graph of the carbon quantum dots and the carbon nitride nanosheet composite material in Example 2 of the application. DETAILED DESCRIPTION

[0037] The application will be described in detail below with reference to the drawings and specific examples. The following examples will help those skilled in the art to further understand the application, but do not limit the application in any form. It should be pointed out that, for those skilled in the art, without departing from the concept of the application, a number of modifications and improvements can be made. These all belong to the protection scope of the application.

[0038] In the technical solution, if the preparation means, materials, structure or composition ratio and other features are not explicitly stated, they are regarded as common technical features disclosed in the prior art.

[0039] In the following examples, the hydrothermal reaction kettle used is a high-temperature and high-pressure reaction kettle.

[0040] In the following examples, the raw materials used can be purchased commercially.

[0041] like Figure 1 FIG. 1 is a flow chart of a method for preparing a carbon nitride nanosheet composite material according to the present invention, wherein the method comprises the following steps:

[0042] S1, mixing the carbon quantum dot precursor and the mixed solvent uniformly and transferring the mixture to a hydrothermal reactor for the first hydrothermal reaction, and obtaining carbon quantum dots after cooling;

[0043] S2, mixing the carbon nitride precursor and the carbon quantum dots obtained in step S1 uniformly and transferring the mixture to a hydrothermal reactor for a second hydrothermal reaction, cooling, washing, and drying to obtain a carbon nitride nanosheet composite material intermediate;

[0044] S3. Drying and fully grinding the carbon nitride nanosheet composite material intermediate obtained in step S2, calcining it under an inert atmosphere, and cooling it to obtain the carbon nitride nanosheet composite material.

[0045] The applicant's conceptual process is as follows: Driven by solar energy, photocatalytic hydrogen production using non-metallic graphite carbon nitride compounds as catalysts is a low-cost and ecologically beneficial technology. However, existing photocatalyst materials all exhibit a wide band gap, a narrow visible light absorption range, and a low redox potential, so that the efficiency of direct photocatalytic water splitting to produce H2 is still very low. Therefore, this project adopts a two-step hydrothermal-calcination tandem synthesis strategy to in situ prepare carbon quantum dots to induce the synthesis of two-dimensional carbon nitride nanosheets. Carbon quantum dots can induce the formation of nanosheets through electron-withdrawing groups, adjust the relative electronic structure (band gap, conduction band, and charge separation rate), and provide more catalytic active sites for the photocatalytic process. Compared with similar graphite carbon nitride materials, our materials currently achieve an H2 production rate of up to 65,000 μmol g -1 h -1 , and the apparent quantum efficiency is 27.5% at 420 nm, which far exceeds that of other reported graphitic carbon nitride photocatalysts.

[0046] Example 1

[0047] This embodiment provides a carbon nitride nanosheet composite material, and the preparation method thereof comprises the following steps:

[0048] S1. Add 50 mg of o-phenylenediamine to 50 mL of acetonitrile solvent, pour the solution after ultrasonication into a high-temperature and high-pressure reactor, and then place it in an oven. Perform a hydrothermal reaction in an oven at 180°C for 12 hours, then cool to room temperature, collect the sample, and obtain carbon quantum dots.

[0049] S2. Add 5 g of melamine and 0.02 g of carbon quantum dot powder (obtained in step S1) to 50 mL of H2O, pour the solution after ultrasonication into a high-temperature and high-pressure reactor, and then place it in an oven. Carry out hydrothermal reaction in an oven at 180°C for 12 hours, then cool to room temperature, collect the sample, wash it alternately with distilled water and anhydrous ethanol 5 times, and then dry it at 60°C for 12 hours to obtain a carbon nitride nanosheet composite material intermediate.

[0050] S3. Place the carbon nitride nanosheet composite material intermediate obtained in step S2 into a crucible with a lid, then place the crucible into a muffle furnace and heat it to 660°C at a heating rate of 5°C / min under a nitrogen atmosphere and keep it for 6 hours. After cooling to room temperature, grind it to obtain a carbon nitride nanosheet composite material (nanosheets composited with carbon quantum dots and carbon nitride).

[0051] Example 2

[0052] This embodiment provides a carbon nitride nanosheet composite material, and the preparation method thereof comprises the following steps:

[0053] S1. Add 25 mg of 2,3-diaminomaleic acid dinitrile and 50 mg of o-phenylenediamine to 50 mL of acetonitrile solvent, pour the solution after ultrasonication into a high-temperature and high-pressure reactor, and then place it in an oven for hydrothermal reaction at 180°C for 12 hours. Then cool it to room temperature, collect the sample, and obtain carbon quantum dots.

[0054] S2. Add 5 g of melamine and 0.02 g of carbon quantum dot powder (obtained in step S1) to 50 mL of H2O, pour the solution after ultrasonication into a high-temperature and high-pressure reactor, and then place it in an oven. Carry out hydrothermal reaction in an oven at 180°C for 12 hours, then cool to room temperature, collect the sample, wash it alternately with distilled water and anhydrous ethanol 5 times, and then dry it at 60°C for 12 hours to obtain a carbon nitride nanosheet composite material intermediate.

[0055] S3. Place the carbon nitride nanosheet composite material intermediate obtained in step S2 into a crucible with a lid, then place the crucible into a muffle furnace and heat it to 660°C at a heating rate of 5°C / min under an argon atmosphere and keep it warm for 6 hours. After cooling to room temperature, grind it to obtain a carbon nitride nanosheet composite material (nanosheets composited with carbon quantum dots and carbon nitride). The obtained carbon nitride nanosheet composite material is a photocatalytic material.

[0056] like Figure 2 As shown in Figure 2, the morphology of CDs-25 and CDs-25 / CN is Figure 2 a and Figure 2 It can be observed in b. Figure 2 a shows that CDs-25 has an average particle size of 2.0 nm and is in a more uniformly dispersed state. Figure 2b It can be seen that CDs-25 / CN is an ultra-thin and uniform sheet with high dispersion, which is conducive to the exposure of the catalytic active centers of the catalyst.

[0057] like Figure 3 As shown in Figure 2, the height and thickness of CDs-25 and CDs-25 / CN can be measured by AFM, as shown in Figure 2. Figure 3 As shown in 3a and 3b. Figure 3 The CDs-25 in a has a height of 1.0 to 1.5 nanometers, which is equivalent to the thickness of 2 to 3 layers of graphene. Figure 3 b shows that CDs-25 / CN has a thickness of 2.0 nm.

[0058] like Figure 4 As shown in the element mapping diagram of CDs-25 / CN, it was observed that C, N and O elements were evenly dispersed in the material.

[0059] like Figure 5 As shown, both CN and CDs-25 / CN conform to type IV isotherms and exhibit unique capillary condensation or evaporation steps, indicating the existence of an ordered mesoporous structure.

[0060] like Figure 6 As shown in Figure 2, the photocatalytic hydrogen production efficiency of CDs-25 / CN can reach 65000 μmol g -1 h -1 .

[0061] Example 3

[0062] This embodiment provides a carbon nitride nanosheet composite material, and the preparation method thereof comprises the following steps:

[0063] S1. Add 50 mg of 2,3-diaminomaleic acid dinitrile and 50 mg of o-phenylenediamine to 50 mL of acetonitrile solvent, pour the solution after ultrasonication into a high-temperature and high-pressure reactor, and then place it in an oven for hydrothermal reaction at 180°C for 12 hours. Then cool it to room temperature, collect the sample, and obtain carbon quantum dots.

[0064] S2. Add 5 g of melamine and 0.02 g of carbon quantum dot powder (obtained in step S1) to 50 mL of H2O, pour the solution after ultrasonication into a high-temperature and high-pressure reactor, and then place it in an oven. Carry out hydrothermal reaction in an oven at 180°C for 12 hours, then cool to room temperature, collect the sample, wash it alternately with distilled water and anhydrous ethanol 5 times, and then dry it at 60°C for 12 hours to obtain a carbon nitride nanosheet composite material intermediate.

[0065] S3, the carbon nitride nanosheet composite material intermediate obtained in step S2 is placed into a crucible with a cover, and then the crucible is placed into a muffle furnace, and the temperature is raised to 660°C at a temperature raising rate of 5°C / min under a mixed atmosphere of nitrogen and argon, and the temperature is kept for 6 h, and after cooling to room temperature, grinding is performed, to obtain a carbon nitride nanosheet composite material (carbon quantum dot and carbon nitride composite nanosheet).

[0066] Example 4

[0067] A carbon nitride nanosheet composite material is provided in this example, and a preparation method thereof includes the following steps:

[0068] S1, 75 mg of 2,3-diamino maleonitrile and 50 mg of o-phenylenediamine are added into 50 mL of acetonitrile solvent, and the solution after ultrasonic treatment is poured into a high-temperature and high-pressure reaction kettle, and then placed in an oven, and a hydrothermal reaction is performed in a 180°C oven for 12 hours, and then cooled to room temperature, and the sample is collected, to obtain carbon quantum dots.

[0069] S2, 5 g of melamine and 0.02 g of carbon quantum dot (obtained in step S1) powder are added into 50 mL of H2O, and the solution after ultrasonic treatment is poured into a high-temperature and high-pressure reaction kettle, and then placed in an oven, and a hydrothermal reaction is performed in a 180°C oven for 12 hours, and then cooled to room temperature, and the sample is collected, and after being washed with distilled water and anhydrous ethanol alternately for 5 times, dried at 60°C for 12 h, to obtain a carbon nitride nanosheet composite material intermediate.

[0070] S3, the carbon nitride nanosheet composite material intermediate obtained in step S2 is placed into a crucible with a cover, and then the crucible is placed into a muffle furnace, and the temperature is raised to 660°C at a temperature raising rate of 5°C / min under a mixed atmosphere of nitrogen and helium, and the temperature is kept for 6 h, and after cooling to room temperature, grinding is performed, to obtain a carbon nitride nanosheet composite material (carbon quantum dot and carbon nitride composite nanosheet).

[0071] Test analysis is as follows:

[0072] 100 mg of the catalyst is added into a solution of 30 mL of deionized water and 20 mL of triethanolamine, and 210 μL of chloroplatinic acid is added dropwise as an electron transport medium, and N2 is passed into the photocatalytic reaction tank for a period of time to exclude the influence of oxygen on the experiment. After the aeration is completed, the photocatalytic hydrogen production system is irradiated with visible light with λ>400 nm, and the products of the system are detected by gas chromatography, and after the light irradiation reaction is completed, the hydrogen production of the sample is calculated.

[0073] The foregoing description of the embodiments has been presented for the purpose of illustration and description. It is not intended to be exhaustive or to limit the application to the precise form disclosed. Modifications and variations are possible in light of the above teachings or can be acquired from practice of the application. As well, the description is presented in the context of the preferred embodiments as a number of alternatives. It is not intended to limit the application to the precise form described.

Claims

1. A method for preparing a carbon nitride nanosheet composite material, characterized in that: The preparation method comprises the following steps: S1. Mix the carbon quantum dot precursor and acetonitrile evenly and transfer the mixture to a hydrothermal reactor for the first hydrothermal reaction. After cooling, carbon quantum dots are obtained. S2, mixing the carbon nitride precursor and the carbon quantum dots obtained in step S1 uniformly and transferring the mixture to a hydrothermal reactor for a second hydrothermal reaction, cooling, washing, and drying to obtain a carbon nitride nanosheet composite material intermediate; S3, drying and fully grinding the carbon nitride nanosheet composite material intermediate obtained in step S2, calcining under an inert atmosphere, and cooling to obtain the carbon nitride nanosheet composite material; The carbon nitride nanosheet composite material is applied in the field of photocatalysis, and the photocatalytic hydrogen production efficiency of the carbon nitride nanosheet composite material reaches 65000 μmol g -1 h -1 .

2. The method for preparing a carbon nitride nanosheet composite material according to claim 1, wherein: In step S1, the carbon quantum dot precursor is selected from one or more of phthalonitrile, 2,3-diaminomaleonitrile, 2-cyanophenylboronic acid, tripyridinecarbonitrile, fumaronitrile, and o-phenylenediamine.

3. The method for preparing a carbon nitride nanosheet composite material according to claim 1, wherein: In step S2, the carbon nitride precursor is selected from one or more of cyanamide, dicyandiamide, ammonium thiocyanate, barbituric acid, melamine, thiourea, and urea.

4. The method for preparing a carbon nitride nanosheet composite material according to claim 1, wherein: In step S2, the mass ratio of the carbon quantum dots to the carbon nitride precursor is 0.004 to 0.

04.

5. The method for preparing a carbon nitride nanosheet composite material according to claim 1, wherein: In step S1, the reaction temperature of the first hydrothermal reaction is 100-200° C., the reaction time is 1-20 h, and the pressure is 0.1-2 MPa.

6. The method for preparing a carbon nitride nanosheet composite material according to claim 1, characterized in that: In step S2, the reaction temperature of the second hydrothermal reaction is 100-200°C, the reaction time is 1-20 h, and the pressure is 0.1-2 MPa.

7. The method for preparing a carbon nitride nanosheet composite material according to claim 1, characterized in that: In step S3, the calcination temperature is 450-700°C, the heating rate is 1-10°C / min, and the holding time is 1-12 h; The inert gas is selected from one of nitrogen, helium, and argon, or a mixture of at least two of them.

8. The method for preparing a carbon nitride nanosheet composite material according to claim 1, characterized in that: In step S3, after the calcination and cooling, the steps of washing, drying and grinding are also included; The cleaning is specifically as follows: using distilled water and anhydrous ethanol to wash alternately 1 to 3 times; The drying is specifically performed at 50-100° C. for 2-12 h.

9. A carbon nitride nanosheet composite material obtained by the preparation method according to any one of claims 1 to 8.

10. An application of a carbon nitride nanosheet composite material obtained by the preparation method according to any one of claims 1 to 8, characterized in that: The carbon nitride nanosheet composite material is applied in the field of photocatalytic hydrogen production.

Images