Preparation method and application of ternary photocatalytic material using black phosphorus as transmission channel

Abstract

This invention provides a method for preparing a ternary photocatalytic material using black phosphorus as a carrier transport channel. Black phosphorus quantum dots are coated on prepared hollow cerium oxide nanospheres, which are then supported on graphite-phase carbon nitride to form a heterojunction, thereby preparing a van der Waals-like heterojunction ternary photocatalytic material. This van der Waals-like heterojunction material combines the advantages of three two-dimensional materials, using black phosphorus as a carrier transport channel to achieve complementary and synergistic performance, thereby improving the material's photocatalytic performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of photocatalytic materials, and in particular relates to a preparation method and application of a ternary photocatalytic material using black phosphorus as a carrier transmission channel. Background Art

[0002] With the rapid development of the economy, human activities have led to the discharge of large amounts of pollutants into oceans, rivers, and lakes, exacerbating the problem of water pollution and greatly endangering human health and the stability of the ecosystem. Photocatalytic technology is an ideal means to solve the problem of water pollution, and photocatalytic materials are the foundation of photocatalytic technology. Single photocatalytic materials have defects such as insufficient light absorption, low carrier transport efficiency, and easy recombination of photogenerated electrons and holes. In order to improve the photocatalytic efficiency, the construction of multi-component composite photocatalytic materials by combining two or more materials to form heterostructures is a current research hotspot.

[0003] Graphitic carbon nitride (g-C3N4) is considered a promising photocatalytic material due to its suitable energy band structure, stable chemical and thermodynamic properties, low cost and easy availability, and environmental friendliness. However, its intrinsic defects such as high photogenerated carrier recombination rate, limited visible light absorption, and low specific surface area severely limit its photocatalytic performance. Cerium dioxide (CeO2) is considered a promising photocatalytic material due to its unique fluorite structure. 4+ / Ce 3+ The presence of a redox pair can act as a charge transfer medium, promoting electron transfer and thus enhancing the photocatalytic performance of the material. Therefore, combining CeO2 with g-C3N4 to construct a binary composite photocatalytic material is an effective method for improving photocatalytic performance. However, binary composite photocatalytic materials still have disadvantages such as insufficient absorption of visible light and the concentration of photogenerated carriers in the same material, which makes them easily recombine.

[0004] Black phosphorus (BP) is a two-dimensional semiconductor material with a layered structure. It has the characteristics of large specific surface area, adjustable direct band gap, wide spectral response range and high carrier mobility, and is considered to be a potential photocatalytic material.

[0005] Black phosphorus, cerium dioxide and graphite carbon nitride are combined to form a ternary photocatalytic material with van der Waals heterojunction properties, which can greatly improve the photocatalytic performance of the material by leveraging the advantages of each of the three materials and complementing their defects. Summary of the Invention

[0006] In response to the shortcomings of existing photocatalytic materials, the purpose of the present invention is to provide a ternary photocatalytic material formed by a composite of black phosphorus, ceria and graphite-phase carbon nitride and a preparation method thereof. The material uses black phosphorus as a carrier transmission channel and tightly combines graphite-phase carbon nitride and ceria, giving full play to the respective advantages of the three materials and complementing their defects. While expanding the light absorption range, it also enhances the mobility of photogenerated carriers, reduces the recombination probability of photogenerated electrons and holes, and effectively improves the catalytic performance of the photocatalytic material.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A ternary photocatalytic material using black phosphorus as a transmission channel, wherein black phosphorus quantum dots are coated on the prepared cerium oxide hollow nanospheres, which are then loaded on g-C3N4 to form a heterojunction. The preparation method includes the following steps:

[0009] S1. Preparation of hollow spherical CeO2: Weigh cerium nitrate hexahydrate (Ce(NO3)3·6H2O) and citric acid monohydrate (C6H8O7·H2O) in proportion, dissolve them in water by ultrasonication, and transfer the mixed solution into a hydrothermal reactor for reaction to obtain hollow spherical CeO2.

[0010] In some embodiments, those skilled in the art would anticipate that the reaction may be followed by post-processing, including collecting the precipitate by centrifugation and washing it with water and anhydrous ethanol. Finally, hollow spherical CeO2 is obtained by vacuum drying at 60°C overnight. The centrifugation conditions are 8,000-10,000 rpm for 3-5 minutes.

[0011] S2. Preparation of black phosphorus quantum dots: Disperse black phosphorus coarse powder in a dispersant, and perform ultrasonic treatment with an horn in an ice bath to obtain black phosphorus quantum dots.

[0012] In some embodiments, it is foreseeable for those skilled in the art that after the ultrasonication, some post-processing steps are required, namely, collecting the precipitate by centrifugation and vacuum drying at 60° C. overnight to obtain black phosphorus quantum dots.

[0013] The centrifugation operation is as follows: first centrifuge at 7000-10000 rpm for 10-15 min to collect the upper suspension, then centrifuge at 10000-12000 rpm for 20-30 min to collect the lower precipitate.

[0014] S3. Preparation of Black Phosphorus-Coated CeO2: Disperse a certain amount of BPQS in oxygen-free water and disperse uniformly using waterbath ultrasonication. Add a proportional amount of hollow CeO2 spheres to the solution and continue ultrasonically dispersing for a specified period. The solution is then transferred to a constant-temperature waterbath and stirred to obtain a suspension. The suspension is then transferred to a hydrothermal reactor for reaction to obtain BPQS@CeO2.

[0015] In some embodiments, it is foreseeable for those skilled in the art that some post-processing is required after the reaction is completed, that is, after the high-pressure reactor is cooled to room temperature, the precipitate is filtered and washed with water and anhydrous ethanol, and finally, BPQS@CeO2 is obtained by vacuum drying at 60°C overnight.

[0016] S4. Preparation of ternary photocatalytic material: Add appropriate amounts of g-C3N4 powder and BPQS@CeO2 to the dispersant, and use water bath ultrasonic treatment to obtain the photocatalytic material BPQS@CeO2-g-C3N4.

[0017] In some embodiments, it is foreseeable for those skilled in the art that after the ultrasonication, some post-processing steps are required, namely, collecting the precipitate by high-speed centrifugation, and finally, vacuum drying at 60°C overnight to obtain the photocatalytic material BPQS@CeO2-g-C3N4.

[0018] Preferably, in steps S2, S3, and S4, the selected solvents are all pre-freeze-pumped to remove oxygen. That is, the dispersion in step S2 is pre-freeze-pumped to remove oxygen; the water and anhydrous ethanol in step S3 are pre-freeze-pumped to remove oxygen; and the dispersant in step S4 is pre-freeze-pumped to remove oxygen.

[0019] The water used in the present invention is deionized water.

[0020] Furthermore, in step S1, the molar ratio of cerium nitrate hexahydrate to citric acid monohydrate is (2-4):1.

[0021] Furthermore, in step S1, the hydrothermal reaction conditions are: temperature 180-210° C., reaction time 2-4 h; and centrifugation conditions are: rotation speed 8000-10000 rpm, centrifugation time 3-5 min.

[0022] Furthermore, in step S2, the dispersant is selected from one or more of N-methylpyrrolidone, N,N-dimethylformamide, dimethyl sulfoxide, anhydrous ethanol and acetone.

[0023] Furthermore, in step S2, the ultrasonic power of the horn is 900 W, the ultrasonic frequency is 2 seconds on and 4 seconds off, and the ultrasonic time is 12 to 36 hours.

[0024] Furthermore, a polar solvent is used as a dispersant, and the precipitate obtained by centrifugation should be washed several times with anhydrous ethanol.

[0025] Furthermore, in step S3, the mass ratio of BPQS to CeO2 is (1-100):100, the mixed suspension is ultrasonicated in a water bath for 30-60 min, and the magnetic stirring time is 2-4 h.

[0026] Furthermore, in step S3, the hydrothermal reaction conditions are: temperature 180-210° C., and reaction time 2-4 h.

[0027] Furthermore, as described in step S4, the mass ratio of g-C3N4 and BPQS@CeO2 is 100:(10~50); the dispersant is a 30%~50% ethanol solution; and the ultrasonic treatment time is 8~12 h.

[0028] The present invention provides a method for preparing a ternary photocatalytic material with black phosphorus as a transmission channel as described in the above technical solution and its application in photocatalytic degradation of pollutants, wherein the pollutants include a solution containing indomethacin, such as an aqueous solution containing indomethacin.

[0029] Compared with the prior art, the beneficial effects of the present invention are embodied in the following aspects:

[0030] Black phosphorus, cerium dioxide and graphite carbon nitride are combined to form a ternary photocatalytic material with van der Waals heterojunction properties, which brings out the advantages of each of the three materials and complements their defects, greatly improving the photocatalytic performance of the material.

[0031] First, the permeability of the shell of cerium oxide hollow nanospheres and the light scattering effect are utilized to increase the light absorption performance; second, the broad-spectrum optical response characteristics of black phosphorus are utilized to make up for the defect of insufficient absorption of visible light range by photocatalytic materials, greatly improving the utilization rate of light; third, the high mobility characteristics of black phosphorus are utilized, and black phosphorus is used as a rapid transmission channel for photogenerated carriers, which effectively promotes the rapid migration of carriers and reduces internal losses; fourth, black phosphorus is used as a transmission channel and connects two heterojunctions. The photogenerated carriers enter the two materials after two separations, which improves the separation efficiency of photogenerated electrons and holes and greatly reduces the recombination probability of photogenerated electrons and holes.

[0032] The ternary photocatalytic material prepared by the present invention has the advantages of simple preparation process, mild conditions, cheap raw materials, strong controllability, high adsorption capacity and is green and pollution-free, and has good application prospects in the field of water pollution degradation. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1Scanning electron micrographs: (a) SEM image of cerium oxide hollow nanospheres prepared in Example 1; (b) SEM image of the ternary photocatalytic material prepared in Example 1.

[0034] Figure 2 This is the EDS spectrum analysis diagram of the ternary photocatalytic material prepared in Example 1.

[0035] Figure 3 This is a comparison chart of the photodegradation activity of indomethacin by photocatalytic materials.

[0036] Figure 4 This is a comparison chart of the photodegradation activity of indomethacin by the photocatalytic material after four consecutive catalytic cycles. DETAILED DESCRIPTION

[0037] The application of the present invention is further illustrated below with reference to specific examples. The following examples are for illustrative purposes only and are not to be construed as limiting the present invention. Unless otherwise specified, the reagents and raw materials used in the following examples are conventional commercially available or commercially available reagents; unless otherwise specified, the equipment used in the following examples is conventionally used in the art.

[0038] Example 1

[0039] S1. Dissolve 413 mg of Ce(NO₃)₃·6H₂O and 100 mg of C₆H₂O in 2 mL of deionized water and sonicate for 30 minutes. The mixed solution was then transferred to a hydrothermal autoclave and placed in a forced-air drying oven at 210°C for 4 hours. After cooling the autoclave to room temperature, centrifuge at 8000 rpm for 3 minutes. Collect the pale yellow precipitate and wash it three times with deionized water and anhydrous ethanol. Finally, dry it in a vacuum oven at room temperature for 8 hours to obtain CeO₂ hollow nanospheres.

[0040] S2. Disperse the crude black phosphorus powder in anhydrous ethanol (oxygen-free anhydrous ethanol) and sonicate with a horn for 24 hours in an ice bath. Centrifuge at 9000 rpm for 15 minutes to collect the supernatant. Centrifuge at 12000 rpm for 20 minutes to collect the precipitate, which was then dried in a vacuum at 60°C overnight to obtain black phosphorus quantum dots (BPQS).

[0041] S3. Disperse 50 mg of BPQS in oxygen-free deionized water and disperse uniformly in a waterbath using ultrasonication. Add 50 mg of CeO2 hollow nanospheres and continue ultrasonication for 60 minutes. Then, transfer the suspension to a 25°C waterbath and continue magnetic stirring for 4 hours to obtain a suspension. The suspension is then transferred to a hydrothermal autoclave, where the air is replaced with nitrogen. The suspension is then placed in a 210°C oven for 4 hours. After the autoclave cools to room temperature, the precipitate is filtered and washed with deionized water and anhydrous ethanol to obtain a 50% BPQS@CeO2 solution. Finally, vacuum dry the solution at 60°C for 12 hours to obtain 50% BPQS@CeO2.

[0042] S4. Add 90 mg of g-C3N4 powder and 10 mg of 50% BPQS@CeO2 to 20 mL of 40% ethanol (oxygen-free ethanol). After nitrogen displacement, the mixed solution was sonicated in a water bath for 8 h. The sample was then collected by high-speed centrifugation and dried in a vacuum oven at 60°C for 12 h to obtain the photocatalytic material g-C3N4-(50% BPQS@CeO2).

[0043] The photocatalytic performance of g-C3N4-(50%BPQS@CeO2) was evaluated using a photocatalytic degradation experiment on an indomethacin solution. After 30 minutes of visible light irradiation, the degradation efficiency of indomethacin was 92%. After four cycles of use, the degradation activity of g-C3N4-(50%BPQS@CeO2) decreased to 75%. The nanoparticles showed no significant agglomeration, and the exposed black phosphorus edges were slightly oxidized, preserving their structure.

[0044] Example 2

[0045] S1. Dissolve 413 mg of Ce(NO₃)₃·6H₂O and 50 mg of C₆H₂O in 2 mL of deionized water and sonicate for 30 minutes. The mixed solution was then transferred to a hydrothermal autoclave and placed in a forced-air drying oven at 180°C for 2 hours. After cooling the autoclave to room temperature, centrifuge at 10,000 rpm for 5 minutes. Collect the pale yellow precipitate and wash it three times with deionized water and anhydrous ethanol. Finally, dry it in a vacuum oven at room temperature for 8 hours to obtain CeO₂ hollow nanospheres.

[0046] S2. Disperse the crude black phosphorus powder in anhydrous ethanol (oxygen-free anhydrous ethanol) and sonicate with a horn for 24 hours in an ice bath. Centrifuge at 9000 rpm for 15 minutes to collect the supernatant. Centrifuge at 12000 rpm for 20 minutes to collect the precipitate, which was then dried in a vacuum at 60°C overnight to obtain black phosphorus quantum dots (BPQS).

[0047] S3. Disperse 30 mg of BPQS in oxygen-free deionized water and disperse uniformly in a waterbath using ultrasonication. Add 70 mg of CeO2 hollow nanospheres and continue ultrasonication for 40 minutes. Then, transfer the suspension to a 25°C waterbath and continuously stir under magnetic stirring for 4 hours to obtain a suspension. The suspension is then transferred to a hydrothermal autoclave, where the air is replaced with nitrogen. The suspension is then placed in a 210°C oven for 2 hours. After cooling the autoclave to room temperature, the precipitate is filtered and washed with deionized water and anhydrous ethanol to obtain a precipitate with 30% BPQS@CeO2. Finally, vacuum dry the suspension at 60°C for 12 hours to obtain 30% BPQS@CeO2.

[0048] S4. Add 70 mg of g-C3N4 powder and 30 mg of 30% BPQS@CeO2 to 20 mL of 40% ethanol (oxygen-free ethanol). After nitrogen displacement, the mixed solution was sonicated in a water bath for 10 h. The sample was then collected by high-speed centrifugation and dried in a vacuum oven at 60°C for 12 h to obtain the photocatalytic material g-C3N4-(30% BPQS@CeO2).

[0049] The photocatalytic performance of g-C3N4-(30%BPQS@CeO2) was evaluated using an indomethacin solution photocatalytic degradation experiment. After 30 minutes of visible light irradiation, the degradation efficiency of indomethacin was 94%. After four cycles of use, the degradation activity of g-C3N4-(30%BPQS@CeO2) decreased to 81%. There was no significant agglomeration of the nanoparticles, and the exposed black phosphorus was slightly oxidized, preserving its structure.

[0050] Example 3

[0051] S1. Dissolve 413 mg of Ce(NO₃)₃·6H₂O and 100 mg of C₆H₂O in 2 mL of deionized water and sonicate for 30 minutes. The mixed solution was then transferred to a hydrothermal autoclave and placed in a forced-air drying oven at 210°C for 4 hours. After cooling the autoclave to room temperature, centrifuge at 8000 rpm for 3 minutes. Collect the pale yellow precipitate and wash it three times with deionized water and anhydrous ethanol. Finally, dry it in a vacuum oven at room temperature for 8 hours to obtain CeO₂ hollow nanospheres.

[0052] S2. Disperse the crude black phosphorus powder in anhydrous ethanol (oxygen-free anhydrous ethanol) and sonicate with a horn for 24 hours in an ice bath. Centrifuge at 9000 rpm for 15 minutes to collect the supernatant. Centrifuge at 12000 rpm for 20 minutes to collect the precipitate, which was then dried in a vacuum at 60°C overnight to obtain black phosphorus quantum dots (BPQS).

[0053] S3. Disperse 10 mg of BPQS in oxygen-free deionized water and disperse uniformly using waterbath sonication. Add 90 mg of CeO2 hollow nanospheres and continue sonication for 30 minutes. Then, transfer the suspension to a 25°C waterbath and magnetically stir for 2 hours. The suspension is then transferred to a hydrothermal autoclave, where the air is replaced with nitrogen and the reaction is continued in an oven at 180°C for 4 hours. After the autoclave cools to room temperature, the precipitate is filtered and washed with deionized water and anhydrous ethanol to obtain 10% BPQS@CeO2. Finally, vacuum dry the suspension at 60°C for 12 hours to obtain 10% BPQS@CeO2.

[0054] S4. Add 70 mg of g-C3N4 powder and 30 mg of 10% BPQS@CeO2 to 20 mL of 50% ethanol (oxygen-free ethanol). After nitrogen displacement, the mixed solution was sonicated in a water bath for 10 h. The sample was then collected by high-speed centrifugation and dried in a vacuum oven at 60°C for 12 h to obtain the photocatalytic material g-C3N4-(10% BPQS@CeO2).

[0055] The photocatalytic performance of g-C3N4-(10%BPQS@CeO2) was evaluated using an indomethacin solution photocatalytic degradation experiment. After 30 minutes of visible light irradiation, the degradation efficiency of indomethacin reached 99%. After four cycles of use, the degradation activity of g-C3N4-(10%BPQS@CeO2) decreased to 95%. There was no significant agglomeration of the nanoparticles, and no significant oxidation of the black phosphorus was observed, indicating that the structure was well-preserved. This decrease in degradation activity is likely due to the inevitable loss of catalytic material during the multiple recycling processes.

[0056] Example 4

[0057] S1. Dissolve 413 mg of Ce(NO₃)₃·6H₂O and 100 mg of C₆H₂O in 2 mL of deionized water and sonicate for 30 minutes. The mixed solution was then transferred to a hydrothermal autoclave and placed in a forced-air drying oven at 210°C for 4 hours. After cooling the autoclave to room temperature, centrifuge at 8000 rpm for 3 minutes. Collect the pale yellow precipitate and wash it three times with deionized water and anhydrous ethanol. Finally, dry it in a vacuum oven at room temperature for 8 hours to obtain CeO₂ hollow nanospheres.

[0058] S2. Disperse the crude black phosphorus powder in anhydrous ethanol (oxygen-free anhydrous ethanol) and sonicate with a horn for 24 hours in an ice bath. Centrifuge at 9000 rpm for 15 minutes to collect the supernatant. Centrifuge at 12000 rpm for 20 minutes to collect the precipitate, which was then dried in a vacuum at 60°C overnight to obtain black phosphorus quantum dots (BPQS).

[0059] S3: Disperse 8 mg of BPQS in oxygen-free deionized water and disperse uniformly in a waterbath using ultrasonication. Add 92 mg of CeO2 hollow nanospheres and continue ultrasonication for 30 minutes. Then, transfer the suspension to a 25°C waterbath and continuously stir under magnetic stirring for 2 hours to obtain a suspension. The suspension was then transferred to a hydrothermal autoclave, where the air was replaced with nitrogen. The suspension was then placed in an oven at 180°C and reacted for 4 hours. After the autoclave cooled to room temperature, the precipitate was filtered and washed with deionized water and anhydrous ethanol to obtain 8% BPQS@CeO2. Finally, vacuum drying was performed at 60°C for 12 hours to obtain 8% BPQS@CeO2.

[0060] S4. Add 50 mg of g-C3N4 powder and 50 mg of 8%BPQS@CeO2 to 20 mL of 50% ethanol (oxygen-free ethanol). After nitrogen displacement, the mixed solution was sonicated in a water bath for 12 h. The sample was then collected by high-speed centrifugation and dried in a vacuum oven at 60°C for 12 h to obtain the photocatalytic material g-C3N4-(8%BPQS@CeO2).

[0061] The photocatalytic performance of g-C3N4-(8%BPQS@CeO2) was evaluated using an indomethacin solution photocatalytic degradation experiment. After 30 minutes of visible light irradiation, the indomethacin degradation efficiency reached 98%. After four cycles of use, the degradation activity of g-C3N4-(8%BPQS@CeO2) decreased to 81%. There was no significant agglomeration of the nanoparticles, and no significant oxidation of the black phosphorus was observed, indicating that the structure was well-preserved.

[0062] Comparative Example 1

[0063] S1. Dissolve 413 mg of Ce(NO₃)₃·6H₂O and 100 mg of C₆H₂O in 2 mL of deionized water and sonicate for 30 minutes. The mixed solution was then transferred to a hydrothermal autoclave and placed in a forced-air drying oven at 210°C for 4 hours. After cooling the autoclave to room temperature, centrifuge at 8000 rpm for 3 minutes. Collect the pale yellow precipitate and wash it three times with deionized water and anhydrous ethanol. Finally, dry it in a vacuum oven at room temperature for 8 hours to obtain CeO₂ hollow nanospheres.

[0064] S2. Add 70 mg of g-C3N4 powder and 30 mg of CeO2 hollow nanospheres to 20 mL of 40% ethanol (oxygen-free ethanol). After nitrogen displacement, the mixed solution was sonicated in a water bath for 12 hours. The sample was then collected by high-speed centrifugation and dried in a vacuum oven at 60°C for 12 hours to obtain the photocatalytic material g-C3N4-CeO2.

[0065] The photocatalytic performance of g-C3N4-CeO2 was evaluated using the photocatalytic degradation experiment of indomethacin solution. After 30 min of visible light irradiation, the degradation efficiency of indomethacin was 83%.

[0066] Comparative Example 2

[0067] S1. Disperse the crude black phosphorus powder in anhydrous ethanol and sonicate with a horn in an ice bath for 24 hours. Centrifuge at 9000 rpm for 15 minutes to collect the supernatant. Centrifuge at 12000 rpm for 20 minutes to collect the precipitate. Dry under vacuum at 60°C overnight to obtain black phosphorus quantum dots (BPQS).

[0068] S2. Add 90 mg of g-C3N4 powder and 10 mg of BPQS to 20 mL of 40% ethanol (oxygen-free ethanol). After nitrogen displacement, the mixed solution was sonicated in a water bath for 12 h. The sample was then collected by high-speed centrifugation and dried in a vacuum oven at 60°C for 12 h to obtain the photocatalytic material g-C3N4-BPQS.

[0069] The photocatalytic performance of g-C3N4-BPQS was evaluated using the photocatalytic degradation experiment of indomethacin solution. After 30 min of visible light irradiation, the degradation efficiency of indomethacin was 65%.

[0070] Comparative Example 3

[0071] 413 mg of Ce(NO₃)₃·6H₂O and 100 mg of C₆H₂Oₐ·H₂O were dissolved in 20 mL of oxygen-free deionized water. Subsequently, 10 mg of the prepared black phosphorus quantum dots and 70 mg of g-C₃N₄ powder were added and dispersed evenly in a waterbath with ultrasonic treatment for 30 minutes. The mixed solution was transferred to a hydrothermal autoclave and reacted in a forced-air drying oven at 210 °C for 4 hours. After the autoclave cooled to room temperature, the reaction mixture was centrifuged at 8000 rpm for 3 minutes. The precipitate was collected and washed three times with deionized water and anhydrous ethanol. Finally, it was dried under vacuum at room temperature for 8 hours to obtain g-C₃N₄-(10%BPQS-CeO₂).

[0072] The photocatalytic performance of g-C3N4-(10%BPQS-CeO2) was evaluated using a photocatalytic degradation experiment on an indomethacin solution. After 30 minutes of visible light irradiation, the degradation efficiency of indomethacin was 91%. After four cycles of use, the degradation activity of g-C3N4-(10%BPQS-CeO2) decreased to 63%. Furthermore, the nanoparticles showed severe agglomeration, the black phosphorus was deeply oxidized, and the structure showed visible disintegration.

[0073] Photocatalytic performance evaluation

[0074] The catalytic performance of the photocatalytic materials prepared in Examples 1 to 4 and Comparative Examples 1 to 3 can be examined by photocatalytically degrading indomethacin solution at room temperature, as follows:

[0075] Disperse 5 mg of photocatalyst in 50 mL of indomethacin solution with a concentration of 5 mg / mL and stir in the dark for 30 min to ensure that adsorption-dissociation equilibrium is reached. Irradiate with visible light from a 300W deuterium lamp (λ≥420nm). At certain time intervals, take 1 mL of the reaction solution and filter the precipitate through a 0.45 μm filter membrane. Use a UV spectrophotometer to measure the absorbance of indomethacin at 320 nm. The degradation of indomethacin can be judged based on the absorbance. Figure 3 After each test, the photocatalyst suspended in the indomethacin solution was collected by high-speed centrifugation and used directly in the next cycle experiment without any treatment. Four consecutive indomethacin photocatalytic degradation experiments were carried out to investigate the stability and recycling performance of the photocatalytic material. Figure 4 shown.

[0076] As can be seen from the activity evaluation graph, black phosphorus has the lowest photocatalytic degradation effect on indomethacin. This may be attributed to the fact that black phosphorus is easily oxidized when exposed to light and water at the same time, and the carriers are almost unable to be effectively separated. The degradation effect of the comparative examples is generally worse than that of the examples, which reflects the advantages of the ternary photocatalytic material. Among them, Comparative Example 3 is compared with Example 3. Example 3 reflects the advantages of the ternary material with van der Waals heterojunction properties, while Comparative Example 3, which is a simple composite of the three materials, cannot function as a transmission channel, resulting in rapid recombination of photogenerated carriers, and thus the degradation effect decreases rapidly in the later stage of the reaction. Compared with Examples 1 to 4, the proportion of black phosphorus in the ternary catalytic material must be appropriate. Too little amount cannot form an effective transmission channel, while too much amount inhibits the effect of cerium oxide and reduces the light absorption performance.

Claims

1. A method for preparing a ternary photocatalytic material using black phosphorus as a transmission channel, characterized in that: The following steps are involved: S1. Preparation of hollow spherical CeO2: Ce(NO3)3·6H2O hexahydrate and citric acid monohydrate C6H8O7·H2O were ultrasonically dissolved in water and then subjected to hydrothermal reaction to obtain hollow spherical CeO2; S2. Preparation of black phosphorus quantum dots: Disperse black phosphorus coarse powder in a dispersant, sonicate with an horn in an ice bath, collect the precipitate by centrifugation, and vacuum dry overnight to obtain black phosphorus quantum dots BPQS; S3. Preparation of black phosphorus-coated CeO2: A certain amount of BPQS was dispersed in water and ultrasonically dispersed to obtain a BPQS solution. Hollow spherical CeO2 was weighed in proportion and added to the BPQS solution. Ultrasonic dispersion was continued for a certain period of time. After stirring to obtain a suspension, a hydrothermal reaction was performed to obtain hollow spherical BPQS@CeO2. S4. Preparation of ternary photocatalytic material: Add appropriate amount of g-C3N4 powder and hollow spherical BPQS@CeO2 to the dispersant, use water bath ultrasonic treatment, collect the precipitate by high-speed centrifugation, and vacuum dry to obtain the photocatalytic material BPQS@CeO2-g-C3N4.

2. The method for preparing the ternary photocatalytic material according to claim 1, characterized in that: The molar ratio of cerium nitrate hexahydrate to citric acid monohydrate in step S1 is (2-4):

1.

3. The method for preparing a ternary photocatalytic material according to claim 1, characterized in that: The hydrothermal reaction conditions in step S1 are: temperature 180-210° C., and reaction time 2-4 h.

4. The method for preparing a ternary photocatalytic material according to claim 1, wherein: In step S2, the dispersant is selected from one or more of N-methylpyrrolidone, N,N-dimethylformamide, dimethyl sulfoxide, anhydrous ethanol and acetone; the ultrasonic power of the horn is 900W, the ultrasonic frequency is 2 seconds on and 4 seconds off, and the ultrasonic time is 12 to 36 hours.

5. The method for preparing a ternary photocatalytic material according to claim 1, wherein: The mass ratio of BPQS to CeO2 in step S3 is (1-100):100, and the mixed suspension is ultrasonicated in a water bath for 30-60 min.

6. The method for preparing a ternary photocatalytic material according to claim 1, characterized in that: The hydrothermal reaction conditions in step S3 are: temperature 180-210° C., and reaction time 2-4 h.

7. The method for preparing a ternary photocatalytic material according to claim 1, characterized in that: In step S4, the mass ratio of g-C3N4 and BPQS@CeO2 is 100:(10~50); the dispersant is a 30%~50% ethanol solution; and the ultrasonic treatment time is 8~12 h.

8. The method for preparing a ternary photocatalytic material according to claim 1, characterized in that: In step S2, the dispersant is deoxygenated by a pre-freezing and pumping operation; in step S3, the water is deoxygenated by a pre-freezing and pumping operation; and in step S4, the dispersant is deoxygenated by a pre-freezing and pumping operation.

9. The method for preparing a ternary photocatalytic material according to any one of claims 1 to 8, characterized in that: The prepared ternary photocatalytic material uses black phosphorus as the transmission channel. Black phosphorus quantum dots are coated on the prepared cerium oxide hollow nanospheres, which are then loaded on g-C3N4 to form a heterojunction, realizing a van der Waals heterojunction-like ternary photocatalytic material.

10. Use of a ternary photocatalytic material prepared by the method according to any one of claims 2 to 9 in photocatalytic degradation of pollutants, wherein the pollutants include a solution containing indomethacin.

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