Preparation method of titanate / graphite phase carbon nitride / titanium dioxide composite nanomaterial

Abstract

The application discloses a preparation method of titanate / graphitic carbon nitride / titanium dioxide composite nanomaterial, which comprises the following steps: preparing a titanate nanomaterial through a high-pressure hydrothermal method; preparing a graphitic carbon nitride nanomaterial through a thermal polycondensation method; adding tetrabutyl titanate, the prepared titanate nanomaterial and the prepared graphitic carbon nitride material into a mixed solution of ethylene glycol and hydrochloric acid to perform a pressurized hydrothermal treatment, and obtaining the titanate / graphitic carbon nitride / titanium dioxide composite nanomaterial. The obtained composite product is light brown, has the advantages of stable property, difficulty in discoloration, high degradation efficiency and the like. The application has the advantages of low cost, simple operation, wide adjustable range of parameters, strong repeatability and large-scale production. The composite material has certain application value in the field of degrading organic pollutants as a photocatalyst.

Description

Technical Field

[0001] This invention relates to a method for preparing titanate / graphite phase carbon nitride / titanium dioxide composite nanomaterials, belonging to the field of composite nanomaterial preparation technology. Background Technology

[0002] The existing technology is as follows:

[0003] 1. The preparation method of graphitic carbon nitride is a simple thermal polycondensation method.

[0004] Specific method: Weigh an appropriate amount of nitrogen-rich precursor and place it in a clean, covered ceramic crucible. Heat the crucible in a muffle furnace to 550℃ at a rate of 2.5℃ / min and hold for 4 hours. After cooling to room temperature, grind it into powder to obtain light yellow graphitic carbon nitride (g-C3N4) powder for later use.

[0005] 2. Layered titanates are prepared using a dilute ammonia hydrothermal method.

[0006] Reference: CN107935034A Few-layer titanium dioxide and its preparation method

[0007] Specific method: Add an appropriate amount of organic titanium salt (Tianate) to 68 ml of 25 wt% ammonia solution, stir and disperse evenly to obtain a suspension, and subject the obtained suspension to hydrothermal reaction treatment at 413.15 K in a high-pressure reactor for 24 hours. After the reaction is completed, obtain the precipitate by filtration or centrifugation, dry it naturally at room temperature, grind it and set it aside for later use to obtain titanate nanosheet material.

[0008] 3. Titanate / graphite phase carbon nitride / titanium dioxide,

[0009] Reference: CN112591792A A simplified method for preparing colored titanium dioxide for photocatalysis

[0010] Specific method: An appropriate amount of organic titanium salt is added to a mixed solution of ethylene glycol and hydrochloric acid, and magnetically stirred until the solution becomes pale yellow and clear. Then, pre-prepared titanate powder and graphitic carbon nitride powder are added, and stirring is continued for 2 hours. The resulting suspension is subjected to hydrothermal reaction treatment at 433.15 K in a high-pressure reactor for 16–24 hours. After the reaction, the precipitate is obtained by filtration or centrifugation, then washed with anhydrous ethanol, and dried to obtain the titanium dioxide / titanium salt / graphitic carbon nitride composite material.

[0011] The excessively wide band gap (3.2 eV) of TiO2 (titanium dioxide) limits its catalytic activity to the ultraviolet (UV) range, resulting in low light utilization and significantly restricting its practical applications. Traditional titanium dioxide photocatalysts are white powders that can only absorb UV light and be excited to generate photocharges, thus performing photocatalytic oxidation or photoelectric conversion. However, they cannot fully utilize the majority of energy from sunlight. In recent years, researchers both domestically and internationally have been working to improve the full-spectrum absorption performance of titanium dioxide materials through various methods, such as metal and non-metal doping, visible-light-responsive semiconductor material synthesis, and photosensitizer sensitization.

[0012] g-C3N4 (graphitic carbon nitride) has high photogenerated electrons, high hole recombination rate, and limited active sites, resulting in a small specific surface area and making it difficult to recycle after use.

[0013] Recent studies have shown that the photocatalytic activity of TiO2 hybridized with g-C3N4 is enhanced due to its unique heterojunction structure. Therefore, preparing TiO2 / g-C3N4 heterojunction photocatalysts is a promising strategy for improving charge separation and enhancing the photocatalytic performance of TiO2. The composite TiO2 / g-C3N4 material can absorb both ultraviolet and visible light.

[0014] Both g-C3N4 and TiO2 are commonly used photocatalytic materials in photocatalysis technology. In recent years, researchers have tended to combine TiO2 and TiO2 to achieve complementary advantages. The resulting TiO2 / g-C3N4 composite material can absorb both ultraviolet and visible light. Furthermore, a heterojunction is formed between the g-C3N4 and TiO2 interfaces, significantly reducing the recombination rate of photogenerated electrons and holes in g-C3N4, thereby enhancing its photocatalytic performance. Conventional photocatalysts are modified before the composite process and then synthesized through a simple hydrothermal reaction. This invention improves the band gap of TiO2 by adding ethylene glycol solvent during the hydrothermal reaction, allowing it to retain certain catalytic performance under visible light. Simultaneously, it is composited with g-C3N4, and an appropriate amount of titanate is added to increase its specific surface area. The resulting composite material possesses certain adsorption and degradation capabilities. Summary of the Invention

[0015] The technical problem to be solved by this invention is that conventional photocatalysts are less efficient at degrading organic pollutants than composite nano-photocatalyst materials.

[0016] To address the aforementioned technical problems, this invention provides a method for preparing titanate / graphite-phase carbon nitride / titanium dioxide composite nanomaterials: titanate nanomaterials are prepared via a high-pressure hydrothermal method; graphite-phase carbon nitride nanomaterials are prepared via thermal polycondensation; tetrabutyl titanate, the prepared titanate nanomaterials, and the graphite-phase carbon nitride material are added to a mixture of ethylene glycol and hydrochloric acid and subjected to pressurized hydrothermal treatment to obtain the titanate / graphite-phase carbon nitride / titanium dioxide composite nanomaterials. The resulting composite product is light brown and possesses advantages such as stable properties, resistance to discoloration, and high degradation efficiency.

[0017] Preferably, the preparation method of the titanate / graphite phase carbon nitride / titanium dioxide composite nanomaterial includes the following steps:

[0018] Step 1): Place the nitrogen-rich precursor into a clean, covered ceramic crucible, heat it in a muffle furnace and keep it at that temperature; after cooling to room temperature, grind it into powder to obtain graphite-phase carbon nitride powder for later use.

[0019] Step 2): Add the organic titanium salt to a 25 wt% ammonia solution, stir and disperse evenly to obtain a suspension, and subject the obtained suspension to hydrothermal reaction treatment at 413.15 K in a high-pressure reactor for 24 hours. After the reaction is completed, obtain the precipitate by filtration or centrifugation, dry it naturally at room temperature, grind it and set it aside for later use to obtain titanate nanosheet material.

[0020] Step 3): Add the organic titanium salt to a mixed solution of ethylene glycol and hydrochloric acid, and stir magnetically until the solution becomes clear. Then add the titanate nanosheet material prepared in Step 2) and the graphite phase carbon nitride powder prepared in Step 1), and continue stirring. The resulting suspension is subjected to hydrothermal reaction in a high-pressure reactor. After the reaction is completed, the precipitate is obtained by filtration or centrifugation, then washed with anhydrous ethanol, and dried to obtain titanium dioxide / titanate / graphite phase carbon nitride composite nanomaterials.

[0021] More preferably, the nitrogen-rich precursor is any one or a combination of several of melamine, dicyandiamide, urea, and thiourea.

[0022] More preferably, the heating rate in step 1) is 2.5℃ / min, and the temperature is maintained at 550℃ for 4 hours.

[0023] More preferably, the organic titanium salt is one or a combination of two of tetrabutyl titanate and isopropyl titanate.

[0024] More preferably, the volume ratio of the organic titanium salt to ethylene glycol and hydrochloric acid is 1:7:2.

[0025] More preferably, the temperature of the hydrothermal reaction in step 3) is 433.15 K and the time is 16 to 24 hours.

[0026] More preferably, the drying method in step 3) is atmospheric pressure drying, vacuum drying, or spray drying.

[0027] More preferably, in the titanate / graphite phase carbon nitride / titanium dioxide composite nanomaterial, the mass ratio of the sum of the titanate nanosheets and the graphite phase carbon nitride powder to the mass of titanium dioxide is 1:1.5.

[0028] This invention is low-cost, simple to operate, has a wide range of adjustable parameters, strong repeatability, and can be mass-produced. As a photocatalyst, this composite material has certain application value in the field of degrading organic pollutants. Attached Figure Description

[0029] Figure 1 Fourier transform infrared spectroscopy (FTIR) of the titanate / graphite-phase carbon nitride / titanium dioxide composite nanomaterials prepared in Example 1;

[0030] Figure 2 The degradation rate of 20 mg / L Rhodamine B dye by the titanate / graphite phase carbon nitride / titanium dioxide composite nanomaterial prepared in Example 5 under 300 W xenon lamp irradiation is shown. Detailed Implementation

[0031] To make the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0032] Example 1

[0033] Weigh 2 grams of melamine and place it in a clean, covered ceramic crucible. Heat the crucible in a muffle furnace to 550°C at a rate of 2.5°C / min and hold for 4 hours. After cooling to room temperature, grind it into powder to obtain a light yellow graphitic carbon nitride powder for later use.

[0034] 5 mL of tetrabutyl titanate was added to 68 mL of 25 wt% ammonia solution and stirred to disperse evenly to obtain a suspension. The resulting suspension was subjected to hydrothermal reaction treatment at 413.15 K in a high-pressure reactor for 24 hours. After the reaction was completed, the precipitate was obtained by filtration or centrifugation, and then dried naturally at room temperature. After grinding, it was used for later use to obtain titanate nanosheet materials.

[0035] The 0.45 g titanate nanosheets and 0.05 g of the prepared graphitic carbon nitride powder were added to a mixed solution of 4 mL tetrabutyl titanate, 28 mL ethylene glycol, and 8 mL hydrochloric acid. The solution was magnetically stirred until it turned a pale yellow and clear color. Then, the pre-prepared titanate powder and graphitic carbon nitride powder were added, and stirring was continued for 2 hours. The resulting suspension was subjected to hydrothermal treatment at 433.15 K in a high-pressure reactor for 16 hours. After the reaction, the precipitate was obtained by filtration or centrifugation, washed with anhydrous ethanol, and dried to obtain the titanium dioxide / titanium dioxide / graphitic carbon nitride composite material. Figure 1 The image shows the Fourier transform infrared (FTIR) analysis of the titanate / graphite-phase carbon nitride / titanium dioxide composite nanomaterials prepared in this embodiment.

[0036] Example 2

[0037] Weigh 2 grams of urea and place it in a clean, covered ceramic crucible. Heat the crucible in a muffle furnace to 550°C at a rate of 2.5°C / min and hold for 4 hours. After cooling to room temperature, grind the urea into powder to obtain a light yellow graphitic carbon nitride powder for later use.

[0038] 8 mL of tetrabutyl titanate was added to 68 mL of 25 wt% ammonia solution and stirred to disperse evenly to obtain a suspension. The resulting suspension was subjected to hydrothermal reaction treatment at 413.15 K in a high-pressure reactor for 24 hours. After the reaction was completed, the precipitate was obtained by filtration or centrifugation, and then dried naturally at room temperature. After grinding, it was used for later use to obtain titanate nanosheet materials.

[0039] The 0.35 g titanate nanosheets and 0.15 g of the prepared graphitic carbon nitride powder were added to a mixed solution of 4 mL tetrabutyl titanate, 28 mL ethylene glycol, and 8 mL hydrochloric acid. The solution was magnetically stirred until it turned a pale yellow and clear color. Then, the pre-prepared titanate powder and graphitic carbon nitride powder were added, and stirring was continued for 2 hours. The resulting suspension was subjected to hydrothermal treatment at 433.15 K in a high-pressure reactor for 18 hours. After the reaction, the precipitate was obtained by filtration or centrifugation, washed with anhydrous ethanol, and dried to obtain the titanium dioxide / titanium dioxide / graphitic carbon nitride composite material.

[0040] Example 3

[0041] Weigh 2 grams of urea and place it in a clean, covered ceramic crucible. Heat the crucible in a muffle furnace to 550°C at a rate of 2.5°C / min and hold for 4 hours. After cooling to room temperature, grind the urea into powder to obtain a light yellow graphitic carbon nitride powder for later use.

[0042] 9 mL of isopropyl titanate was added to 68 mL of 25 wt% ammonia solution and stirred to disperse evenly to obtain a suspension. The resulting suspension was subjected to hydrothermal reaction treatment at 413.15 K in a high-pressure reactor for 24 hours. After the reaction was completed, the precipitate was obtained by filtration or centrifugation, and then dried naturally at room temperature. After grinding, it was used for later use to obtain titanate nanosheet materials.

[0043] The 0.25 g titanate nanosheets and 0.25 g of the prepared graphitic carbon nitride powder were added to a mixed solution of 4 mL tetrabutyl titanate, 28 mL ethylene glycol, and 8 mL hydrochloric acid. The solution was magnetically stirred until it turned a pale yellow and clear color. Then, the pre-prepared titanate powder and graphitic carbon nitride powder were added, and stirring was continued for 2 hours. The resulting suspension was subjected to hydrothermal treatment at 433.15 K in a high-pressure reactor for 20 hours. After the reaction, the precipitate was obtained by filtration or centrifugation, washed with anhydrous ethanol, and dried to obtain the titanium dioxide / titanium dioxide / graphitic carbon nitride composite material.

[0044] Example 4

[0045] Weigh 2 grams of melamine and place it in a clean, covered ceramic crucible. Heat the crucible in a muffle furnace to 550°C at a rate of 2.5°C / min and hold for 4 hours. After cooling to room temperature, grind it into powder to obtain a light yellow graphitic carbon nitride powder for later use.

[0046] 10 mL of tetrabutyl titanate was added to 68 mL of 25 wt% ammonia solution and stirred to disperse evenly to obtain a suspension. The resulting suspension was subjected to hydrothermal reaction treatment at 413.15 K in a high-pressure reactor for 24 hours. After the reaction was completed, the precipitate was obtained by filtration or centrifugation, and then dried naturally at room temperature. After grinding, it was used for later use to obtain titanate nanosheet materials.

[0047] The 0.15 g titanate nanosheets and 0.35 g of the prepared graphitic carbon nitride powder were added to a mixed solution of 4 mL tetrabutyl titanate, 28 mL ethylene glycol, and 8 mL hydrochloric acid. The solution was magnetically stirred until it turned a pale yellow and clear color. Then, the pre-prepared titanate powder and graphitic carbon nitride powder were added, and stirring was continued for 2 hours. The resulting suspension was subjected to hydrothermal treatment at 433.15 K in a high-pressure reactor for 16 hours. After the reaction, the precipitate was obtained by filtration or centrifugation, washed with anhydrous ethanol, and dried to obtain the titanium dioxide / titanium dioxide / graphitic carbon nitride composite material.

[0048] Example 5

[0049] Weigh 2 grams of melamine and place it in a clean, covered ceramic crucible. Heat the crucible in a muffle furnace to 550°C at a rate of 2.5°C / min and hold for 4 hours. After cooling to room temperature, grind it into powder to obtain a light yellow graphitic carbon nitride powder for later use.

[0050] Nine milliliters of tetrabutyl titanate were added to 68 milliliters of 25 wt% ammonia solution and stirred to disperse evenly to obtain a suspension. The resulting suspension was subjected to hydrothermal reaction treatment at 413.15 K in a high-pressure reactor for 24 hours. After the reaction was completed, the precipitate was obtained by filtration or centrifugation, and then dried naturally at room temperature. After grinding, it was used for later use to obtain titanate nanosheet materials.

[0051] The 0.05 g titanate nanosheets and 0.45 g of the prepared graphitic carbon nitride powder were added to a mixed solution of 4 mL tetrabutyl titanate, 28 mL ethylene glycol, and 8 mL hydrochloric acid. The solution was magnetically stirred until it turned a pale yellow and clear color. Then, the pre-prepared titanate powder and graphitic carbon nitride powder were added, and stirring was continued for 2 hours. The resulting suspension was subjected to hydrothermal treatment at 433.15 K in a high-pressure reactor for 16 hours. After the reaction, the precipitate was obtained by filtration or centrifugation, washed with anhydrous ethanol, and dried to obtain the titanium dioxide / titanium dioxide / graphitic carbon nitride composite material.

[0052] Figure 2 The degradation rate of 20 mg / L Rhodamine B dye by the titanate / graphite phase carbon nitride / titanium dioxide composite nanomaterial prepared in this embodiment under 300 W xenon lamp irradiation.

[0053] Example 6

[0054] Weigh 2 grams of melamine and place it in a clean, covered ceramic crucible. Heat the crucible in a muffle furnace to 550°C at a rate of 2.5°C / min and hold for 4 hours. After cooling to room temperature, grind it into powder to obtain a light yellow graphitic carbon nitride powder for later use.

[0055] 9 mL of isopropyl titanate was added to 68 mL of 25 wt% ammonia solution and stirred to disperse evenly to obtain a suspension. The resulting suspension was subjected to hydrothermal reaction treatment at 413.15 K in a high-pressure reactor for 24 hours. After the reaction was completed, the precipitate was obtained by filtration or centrifugation, and then dried naturally at room temperature. After grinding, it was used for later use to obtain titanate nanosheet materials.

[0056] The 0.05 g titanate nanosheets and 0.45 g of the prepared graphitic carbon nitride powder were added to a mixed solution of 4 mL tetrabutyl titanate, 28 mL ethylene glycol, and 8 mL hydrochloric acid. The solution was magnetically stirred until it turned a pale yellow and clear color. Then, the pre-prepared titanate powder and graphitic carbon nitride powder were added, and stirring was continued for 2 hours. The resulting suspension was subjected to hydrothermal treatment at 433.15 K in a high-pressure reactor for 16 hours. After the reaction, the precipitate was obtained by filtration or centrifugation, washed with anhydrous ethanol, and dried to obtain the titanium dioxide / titanium dioxide / graphitic carbon nitride composite material.

[0057] Example 7

[0058] Weigh 2 grams of melamine and place it in a clean, covered ceramic crucible. Heat the crucible in a muffle furnace to 550°C at a rate of 2.5°C / min and hold for 4 hours. After cooling to room temperature, grind it into powder to obtain a light yellow graphitic carbon nitride powder for later use.

[0059] Nine milliliters of tetrabutyl titanate were added to 68 milliliters of 25 wt% ammonia solution and stirred to disperse evenly to obtain a suspension. The resulting suspension was subjected to hydrothermal reaction treatment at 413.15 K in a high-pressure reactor for 24 hours. After the reaction was completed, the precipitate was obtained by filtration or centrifugation, and then dried naturally at room temperature. After grinding, it was used for later use to obtain titanate nanosheet materials.

[0060] The 0.40 g titanate nanosheets and 0.10 g of the prepared graphitic carbon nitride powder were added to a mixed solution of 4 mL tetrabutyl titanate, 28 mL ethylene glycol, and 8 mL hydrochloric acid. The solution was magnetically stirred until it turned a pale yellow and clear color. Then, the pre-prepared titanate powder and graphitic carbon nitride powder were added, and stirring was continued for 2 hours. The resulting suspension was subjected to hydrothermal treatment at 433.15 K in a high-pressure reactor for 18 hours. After the reaction, the precipitate was obtained by filtration or centrifugation, washed with anhydrous ethanol, and dried to obtain the titanium dioxide / titanium dioxide / graphitic carbon nitride composite material.

[0061] Example 8

[0062] Weigh 2 grams of melamine and place it in a clean, covered ceramic crucible. Heat the crucible in a muffle furnace to 550°C at a rate of 2.5°C / min and hold for 4 hours. After cooling to room temperature, grind it into powder to obtain a light yellow graphitic carbon nitride powder for later use.

[0063] Nine milliliters of tetrabutyl titanate were added to 68 milliliters of 25 wt% ammonia solution and stirred to disperse evenly to obtain a suspension. The resulting suspension was subjected to hydrothermal reaction treatment at 413.15 K in a high-pressure reactor for 24 hours. After the reaction was completed, the precipitate was obtained by filtration or centrifugation, and then dried naturally at room temperature. After grinding, it was used for later use to obtain titanate nanosheet materials.

[0064] The 0.10 g titanate nanosheets and 0.40 g of the prepared graphitic carbon nitride powder were added to a mixed solution of 4 mL tetrabutyl titanate, 28 mL ethylene glycol, and 8 mL hydrochloric acid. The solution was magnetically stirred until it turned a pale yellow and clear color. Then, the pre-prepared titanate powder and graphitic carbon nitride powder were added, and stirring was continued for 2 hours. The resulting suspension was subjected to hydrothermal treatment at 433.15 K in a high-pressure reactor for 20 hours. After the reaction, the precipitate was obtained by filtration or centrifugation, washed with anhydrous ethanol, and dried to obtain the titanium dioxide / titanium dioxide / graphitic carbon nitride composite material.

[0065] Example 9

[0066] Weigh 2 grams of melamine and place it in a clean, covered ceramic crucible. Heat the crucible in a muffle furnace to 550°C at a rate of 2.5°C / min and hold for 4 hours. After cooling to room temperature, grind it into powder to obtain a light yellow graphitic carbon nitride powder for later use.

[0067] Nine milliliters of tetrabutyl titanate were added to 68 milliliters of 25 wt% ammonia solution and stirred to disperse evenly to obtain a suspension. The resulting suspension was subjected to hydrothermal reaction treatment at 413.15 K in a high-pressure reactor for 24 hours. After the reaction was completed, the precipitate was obtained by filtration or centrifugation, and then dried naturally at room temperature. After grinding, it was used for later use to obtain titanate nanosheet materials.

[0068] The 0.10 g titanate nanosheets and 0.40 g of the prepared graphitic carbon nitride powder were added to a mixed solution of 4 mL tetrabutyl titanate, 28 mL ethylene glycol, and 8 mL hydrochloric acid. The solution was magnetically stirred until it turned a pale yellow and clear color. Then, the pre-prepared titanate powder and graphitic carbon nitride powder were added, and stirring was continued for 2 hours. The resulting suspension was subjected to hydrothermal treatment at 433.15 K in a high-pressure reactor for 22 hours. After the reaction, the precipitate was obtained by filtration or centrifugation, washed with anhydrous ethanol, and dried to obtain the titanium dioxide / titanium dioxide / graphitic carbon nitride composite material.

[0069] Example 10

[0070] Weigh 2 grams of melamine and place it in a clean, covered ceramic crucible. Heat the crucible in a muffle furnace to 550°C at a rate of 2.5°C / min and hold for 4 hours. After cooling to room temperature, grind it into powder to obtain a light yellow graphitic carbon nitride powder for later use.

[0071] Nine milliliters of tetrabutyl titanate were added to 68 milliliters of 25 wt% ammonia solution and stirred to disperse evenly to obtain a suspension. The resulting suspension was subjected to hydrothermal reaction treatment at 413.15 K in a high-pressure reactor for 24 hours. After the reaction was completed, the precipitate was obtained by filtration or centrifugation, and then dried naturally at room temperature. After grinding, it was used for later use to obtain titanate nanosheet materials.

[0072] The 0.10 g titanate nanosheets and 0.40 g of the prepared graphitic carbon nitride powder were added to a mixed solution of 4 mL tetrabutyl titanate, 28 mL ethylene glycol, and 8 mL hydrochloric acid. The solution was magnetically stirred until it turned a pale yellow and clear color. Then, the pre-prepared titanate powder and graphitic carbon nitride powder were added, and stirring was continued for 2 hours. The resulting suspension was subjected to hydrothermal treatment at 433.15 K in a high-pressure reactor for 24 hours. After the reaction, the precipitate was obtained by filtration or centrifugation, washed with anhydrous ethanol, and dried to obtain the titanium dioxide / titanium dioxide / graphitic carbon nitride composite material.

Claims

1. A method for preparing titanate / graphite-phase carbon nitride / titanium dioxide composite nanomaterials, characterized in that, Titanate nanomaterials were prepared by a high-pressure hydrothermal method; graphite-phase carbon nitride nanomaterials were prepared by thermal polycondensation; the organic titanium salt, the prepared titanate nanomaterials, and the graphite-phase carbon nitride material were added to a mixture of ethylene glycol and hydrochloric acid and subjected to pressurized hydrothermal treatment to obtain titanate / graphite-phase carbon nitride / titanium dioxide composite nanomaterials; the specific steps included are as follows: Step 1): Place the nitrogen-rich precursor into a clean, covered ceramic crucible, heat it in a muffle furnace and keep it at that temperature; after cooling to room temperature, grind it into powder to obtain graphite-phase carbon nitride powder for later use. Step 2): Add the organic titanium salt to a 25wt% ammonia solution, stir and disperse evenly to obtain a suspension. The obtained suspension is subjected to hydrothermal reaction treatment at 413.15K in a high-pressure reactor for 24 hours. After the reaction is completed, the precipitate is obtained by filtration or centrifugation, and then dried naturally at room temperature. After grinding, it is used for later use to obtain titanate nanosheet material. Step 3): Add the organic titanium salt to a mixed solution of ethylene glycol and hydrochloric acid, and stir magnetically until the solution becomes clear. Then add the titanate nanosheet material prepared in Step 2) and the graphite phase carbon nitride powder prepared in Step 1), and continue stirring. The resulting suspension is subjected to hydrothermal reaction in a high-pressure reactor. After the reaction is completed, the precipitate is obtained by filtration or centrifugation, then washed with anhydrous ethanol, and dried to obtain titanium dioxide / titanate / graphite phase carbon nitride composite nanomaterials.

2. The method for preparing titanate / graphite-phase carbon nitride / titanium dioxide composite nanomaterials as described in claim 1, characterized in that, The nitrogen-rich precursor is any one or a combination of several of melamine, dicyandiamide, urea, and thiourea.

3. The preparation method of the titanate / graphite-phase carbon nitride / titanium dioxide composite nanomaterial as described in claim 1, characterized in that, In step 1), the heating rate is 2.5℃ / min, and the temperature is maintained at 550℃ for 4 hours.

4. The preparation method of the titanate / graphite-phase carbon nitride / titanium dioxide composite nanomaterial as described in claim 1, characterized in that, The organic titanium salt is one or a combination of two of tetrabutyl titanate and isopropyl titanate.

5. The method for preparing titanate / graphite-phase carbon nitride / titanium dioxide composite nanomaterials as described in claim 1, characterized in that, The volume ratio of the organic titanium salt to ethylene glycol and hydrochloric acid is 1:7:

2.

6. The method for preparing titanate / graphite-phase carbon nitride / titanium dioxide composite nanomaterials as described in claim 1, characterized in that, In step 3), the hydrothermal reaction temperature is 433.15 K and the time is 16-24 hours.

7. The method for preparing titanate / graphite-phase carbon nitride / titanium dioxide composite nanomaterials as described in claim 1, characterized in that, The drying method in step 3) is atmospheric pressure drying, vacuum drying, or spray drying.

8. The method for preparing titanate / graphite-phase carbon nitride / titanium dioxide composite nanomaterials as described in claim 1, characterized in that, In the titanate / graphite phase carbon nitride / titanium dioxide composite nanomaterial, the sum of the masses of titanate nanosheets and graphite phase carbon nitride powder is in a mass ratio of 1:1.5 to that of titanium dioxide.

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