Phosphorene-based composite material, preparation method thereof and application of phosphorene-based composite material in medical wastewater treatment

Abstract

The invention belongs to the technical field of photocatalysts, and discloses a phosphorene-based composite material, a preparation method thereof and application of the phosphorene-based composite material in medical wastewater treatment, the phosphorene-based composite material comprises a purple phosphorus / black phosphorus heterojunction and noble metal nanoparticles anchored at the edge of the heterojunction; a phase junction electric field is formed at the interface of the purple phosphorus / black phosphorus heterojunction, an edge local electric field is formed between the precious metal nanoparticles and the purple phosphorus / black phosphorus heterojunction, and the phase junction electric field and the edge local electric field jointly form an integrated double-electric-field system. According to the integrated double-electric-field system of the phosphorene-based composite material, directional and rapid transmission of photo-induced electrons from a bulk phase to an edge active center can be realized, the charge separation efficiency is greatly improved, the reverse reaction is effectively inhibited, and meanwhile, the overall quantum efficiency is improved; in medical wastewater treatment, a green reaction path of treating waste with waste is constructed, and thorough mineralization of pollutants and in-situ conversion of carbon resources are realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photocatalysts, and particularly relates to a phosphorene-based composite material, a preparation method thereof and application of the phosphorene-based composite material in medical wastewater treatment. BACKGROUND

[0003] Combining the degradation of organic pollutants with the photocatalytic reduction of CO2 to construct an oxidation-reduction synergistic reaction system is considered to be a forward-looking strategy for realizing the treatment of waste with waste and carbon cycle. However, the efficient operation of the system is highly dependent on the efficient separation and directional migration of photo-generated electrons and holes, and the spatial precise construction of oxidation and reduction active sites. The photocatalytic materials in the prior art generally have problems such as serious carrier recombination and disordered distribution of reaction sites, which limit the further improvement of the synergistic reaction efficiency.

[0004] Phosphorene materials (such as black phosphorus BP and purple phosphorus VP) have high carrier mobility and adjustable band gap, and have great potential in the field of photocatalysis, but their intrinsic structure lacks effective charge guiding mechanism and reaction site isolation ability, which is difficult to meet the needs of complex coupled reactions. Therefore, developing a new type of photocatalytic material with efficient charge separation and spatial site isolation functions has become a key breakthrough in the development of the field. SUMMARY

[0005] In order to solve the problems of the existing materials in charge separation and reaction site regulation, the purpose of the present application is to provide a phosphorene-based composite material with exquisite structure and excellent performance and a preparation method thereof. Meanwhile, the application of the phosphorene-based composite material in medical wastewater treatment is disclosed.

[0006] To achieve the above-mentioned purpose of the application, the following technical solutions are adopted: A phosphorene-based composite material comprises a purple phosphorus / black phosphorus heterojunction and noble metal nanoparticles anchored at the edge of the heterojunction; a junction electric field is formed at the interface of the purple phosphorus / black phosphorus heterojunction, and an edge-localized electric field is formed between the noble metal nanoparticles and the purple phosphorus / black phosphorus heterojunction, and the junction electric field and the edge-localized electric field jointly constitute an integrated double electric field system.

[0007] Further, the noble metal nanoparticles are one or more of rhodium, platinum, silver and gold.

[0008] Further, the loading amount of the noble metal nanoparticles is 0.5-10 wt% of the total mass of the purple phosphorus / black phosphorus heterojunction.

[0009] A preparation method of a phosphorene-based composite material comprises the following steps: S1, preparing a purple phosphorus / black phosphorus heterojunction; S2, mixing the purple phosphorus / black phosphorus heterojunction obtained in step S1 with a noble metal precursor solution to obtain a first mixture; S3, performing a photochemical reduction reaction on the first mixture obtained in step S2 to selectively deposit noble metal nanoparticles on the edges of the purple phosphorus / black phosphorus heterojunction, to obtain a purple phosphorus / black phosphorus heterojunction composite material loaded with noble metal nanoparticles, i.e. a phosphene-based composite material.

[0010] Further, the above step S1 comprises the following sub-steps: S1.1, mixing bulk purple phosphorus with black phosphorus, then adding a polar organic solvent to fully wet the purple phosphorus and black phosphorus and form a paste-like mixture, and continuously grinding to obtain a second mixture; S1.2, ultrasonic treatment of the second mixture obtained in step S1.1 to obtain a first dispersion liquid; S1.3, low-speed centrifugal treatment of the first dispersion liquid obtained in step S1.2, collecting the supernatant, then high-speed centrifugal treatment, collecting the centrifuged sample, and vacuum drying to obtain a purple phosphorus / black phosphorus heterojunction.

[0011] Further, in the above step S1.1, the mass ratio of bulk purple phosphorus to black phosphorus is 1:3 to 3:1, and the ratio of the mixture of purple phosphorus and black phosphorus to the polar organic solvent is 1:10-100 mg / mL.

[0012] Further, the above polar organic solvent is one or more of N-methyl-2-pyrrolidone, dimethyl sulfoxide, isopropyl alcohol, N,N dimethylformamide, and methanol.

[0013] Further, in the above step S1.1, the grinding time is 10-60 min.

[0014] Further, in the above step S1.2, the temperature condition is 0-10℃, the ultrasonic treatment time is 2-6h, and the ultrasonic power is 30-100 W.

[0015] Further, in the above step S1.3, the low-speed centrifugation speed is 2000-5000 rpm, and the treatment time is 5-15 min; the high-speed centrifugation speed is 8000-15000 rpm, and the treatment time is 5-15 min.

[0016] Further, in the above step S1.3, the vacuum drying conditions are: vacuum degree 0.01-0.1 bar, temperature 40-60℃, and time 10-12h.

[0017] Further, in the above step S1.3, the purple phosphorus / black phosphorus heterojunction is a nanosheet structure with a thickness of 1-10 nm and a lateral size of 0.1-2 mm.

[0018] Further, the step S2 described above comprises the following sub-steps: S2.1, dispersing the purple phosphorus / black phosphorus heterojunction obtained in step S1 in deionized water, and performing ultrasonic treatment to form a uniform second dispersion liquid; S2.2, adding a noble metal precursor solution to the second dispersion liquid obtained in step S2.1, and performing magnetic stirring reaction to make noble metal ions fully adsorbed on the surface and edges of the purple phosphorus / black phosphorus heterojunction material, thereby obtaining a first mixture.

[0019] Further, in step S2.1 described above, the ratio of purple phosphorus / black phosphorus heterojunction to deionized water is 1:1-5 mg / mL.

[0020] Further, in step S2.1 described above, the ultrasonic power is 50-200 W, and the ultrasonic treatment time is 10-30 min.

[0021] Further, in step S2.2 described above, the volume ratio of noble metal precursor solution to second dispersion liquid is 1:100-200.

[0022] Further, in step S2.2 described above, the noble metal precursor solution is prepared by dispersing a noble metal precursor in a mixed solvent; wherein the noble metal precursor is any one of RhCl3, H2PtCl6, AgNO3, and HAuCl4, the mixed solvent is a solution prepared by mixing an organic solvent and deionized water in a volume ratio of 1:5-9, the organic solvent is any one of methanol, triethanolamine, sodium oxalate, and ethylenediaminetetraacetic acid disodium, and the concentration of the noble metal precursor solution is 5-20 mg / mL.

[0023] Further, in step S2.2 described above, the magnetic stirring conditions are as follows: the stirring speed is 200-600 rpm, and the reaction time is 15-60 min.

[0024] Further, the step S3 described above comprises the following sub-steps: S3.1, performing vacuum treatment on the first mixture obtained in step S2; S3.2, irradiating the first mixture treated in step S3.1 with a light source having a wavelength of 420-800 nm for 15-30 min to perform photochemical reduction reaction; after the reaction is completed, the product mixture is filtered, washed repeatedly with deionized water and anhydrous ethanol, and finally vacuum dried to obtain the target product, i.e., a purple phosphorus / black phosphorus heterojunction composite material loaded with noble metal nanoparticles.

[0025] Further, in the step S3.1, the vacuum treatment is performed under the conditions of a vacuum degree of 0.01-0.1 bar, a temperature of 10-20℃, and a time of 15-30 min.

[0026] Further, in the step S3.2, the vacuum drying is performed under the conditions of a vacuum degree of 0.01-0.1 bar, a temperature of 60-80℃, and a time of 10-12 h.

[0027] The application further discloses application of the phosphorene-based composite material as a photocatalyst in medical wastewater treatment through a photocatalytic reaction.

[0028] Further, the photocatalytic reaction is a coupling reaction of simultaneous degradation of organic pollutants and reduction of CO2.

[0029] Further, the organic pollutants include, but are not limited to, drugs and personal care products, endocrine disruptors, an antitumor drug 5-fluorouracil and intermediate degradation products thereof in medical wastewater.

[0030] A photocatalytic system for performing the photocatalytic reaction, which uses the phosphorene-based composite material as a catalyst, operates under irradiation of a light source and in anoxic or anaerobic conditions.

[0031] Further, the photocatalytic system uses a xenon lamp, a mercury lamp or an LED light source as the light source, simulates sunlight, AM1.5G, and has a wavelength range of 200-1100 nm.

[0032] Due to the technical scheme, the application has the following advantages: The phosphorene-based composite material has a phase junction electric field (PEF) which is generated by an atomic-level coherent heterojunction formed by a violet phosphorus (VP) and a black phosphorus (BP), is induced by an interface band alignment difference, provides a strong driving force for separation of a bulk phase photo-generated electron-hole pair, and has an edge local electric field (FEF) which is formed by selective anchoring of a noble metal nanoparticle at an edge of the violet phosphorus / black phosphorus (VP / BP), forms a Schottky contact, and guides directional migration of an electron to an edge metal site.

[0033] The phosphene-based composite material of the present application integrates a double electric field system (DEF) to overcome the disadvantage of radial charge migration without guidance of the phosphene material, can realize the cascade migration path of electrons from violet phosphorus (VP) to black phosphorus (BP) to the edge metal, realize the direction and rapid transmission of photo-generated electrons from the bulk phase to the edge active center, greatly improve the charge separation efficiency, realize the accurate separation of oxidation sites (VP / BP basal plane) and reduction sites (edge metal) in space, effectively inhibit the reverse reaction, and optimize the adsorption / activation of reactants (CO2, H2O) and intermediates, reduce the reaction energy barrier, and improve the overall quantum efficiency.

[0034] The phosphene-based composite material of the present application in the "pollutant degradation + CO2 reduction" coupling system promotes pollutants and CO2, the pollutant degradation as a sacrifice reaction drives the efficient CO2 reduction, the acceleration of the CO2 reduction half-reaction also weakens the speed-limiting effect on the oxidation half-reaction, builds a green reaction path of "waste treatment with waste", realizes the complete mineralization of pollutants and in-situ conversion of carbon resources.

[0035] The preparation method of the phosphene-based composite material of the present application has a simple process flow and accurate positioning, uses edge-specific photoreduction technology, uses the unsaturated P-P dangling bond at the edge of violet phosphorus / black phosphorus (VP / BP) as a preferential nucleation site, realizes the selective deposition and chemical bonding of noble metals in the edge region; suitable for modification of various noble metals, and the prepared phosphene-based composite material still shows excellent catalytic activity and long-term operation stability in a complex water-gas-solid reaction environment. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a flowchart of the preparation method of the VP / BP-Rh composite material in Example 1; Figure 2 is a high-magnification transmission electron microscope, atomic structure and corresponding element mapping of the VP / BP-Rh composite material in Example 1; Figure 3 is the X-ray diffraction pattern of the VP / BP-Rh composite material in Example 1; Figure 4 is the Rh 3d X-ray photoelectron spectrum of the VP / BP-Rh composite material in Example 1; Figure 5 is the VP / BP-Rh structure model and the difference charge density map based on the density functional theory calculation; Figure 6 is a comparison chart of the photocurrent response of VP, VP / BP and the VP / BP-Rh composite material in Example 1; Figure 7 is a working principle diagram of a photocatalytic carbon cycle system; Figure 8 is a structural schematic diagram of a photocatalytic reaction device; Figure 9 is a photocatalytic CO2 reduction product yield graph of the VP / BP-Rh composite material and comparative materials in Example 1; Figure 10 is a curve graph of the degradation rate of NPX and the total organic carbon removal rate of the VP / BP-Rh composite material in Example 1 over time; Figure 11 is a graph of the effect of different active species trapping agents on the photocatalytic degradation of NPX by VP / BP-Rh; Figure 12 is a transmission electron microscope image of different noble metal modified phosphene-based composite materials; Figure 13 is a performance comparison graph of different noble metal modified composite materials for photocatalytic degradation of NPX. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0038] A phosphene-based composite material includes a purple phosphorus / black phosphorus heterojunction (VP / BP heterojunction) and noble metal nanoparticles anchored at the edge of the heterojunction. A junction electric field (PEF) is formed at the interface of the purple phosphorus / black phosphorus heterojunction, and an edge localized electric field (FEF) is formed between the noble metal nanoparticles and the purple phosphorus / black phosphorus heterojunction. The junction electric field and the edge localized electric field together form an integrated double electric field system (DEF).

[0039] The noble metal nanoparticles described above are one or more of rhodium, platinum, silver, and gold, and are preferably rhodium (Rh).

[0040] The loading amount of the noble metal nanoparticles described above is 0.5-10 wt% of the total mass of the purple phosphorus / black phosphorus heterojunction, preferably 1-7 wt%, and more preferably 5 wt%.

[0041] As shown in Figure 1 , a preparation method of a phosphene-based composite material includes the following steps: S1, preparing a VP / BP heterojunction, including the following sub-steps: S1.1, mixing the bulk VP with the BP, then adding a polar organic solvent to fully wet the VP and BP and form a paste-like mixture, continuously grinding for 10-60 min to obtain a second mixture; the mass ratio of the bulk VP to the BP is 1:3 to 3:1, and the feed liquid ratio of the mixture of the VP and the BP to the polar organic solvent is 1:10-100 mg / mL; the polar organic solvent is one or more of N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide, isopropyl alcohol, N,N dimethylformamide, and methanol; S1.2, ultrasonic treatment of the second mixture obtained in step S1.1 at a temperature of 0-10°C for 2-6 h at an ultrasonic power of 30-100 W to obtain a first dispersion; S1.3, low-speed centrifugal treatment of the first dispersion obtained in step S1.2 at a speed of 2000-5000 rpm for 5-15 min to remove the unpeeled bulk VP and BP, collection of the supernatant, followed by high-speed centrifugal treatment at a speed of 8000-15000 rpm for 5-15 min, collection of the centrifuged sample, and vacuum drying at a temperature of 40-60°C for 10-12 h at a vacuum degree of 0.01-0.1 bar to obtain a VP / BP heterojunction; the VP / BP heterojunction is in a nanosheet structure with a thickness of 1-10 nm and a lateral size of 0.1-2 mm; S2, mixing the VP / BP heterojunction obtained in step S1 with a noble metal precursor solution to obtain a first mixture; comprising the following sub-steps: S2.1, dispersing the VP / BP heterojunction obtained in step S1 in deionized water, ultrasonic treatment for 10-30 min at an ultrasonic power of 50-200 W to form a uniform second dispersion; the feed liquid ratio of the VP / BP heterojunction to the deionized water is 1:1-5 mg / mL; S2.2, adding a noble metal precursor solution to the second dispersion obtained in step S2.1, the volume ratio of the noble metal precursor solution to the second dispersion is 1:100-200, and magnetic stirring is carried out at a stirring speed of 200-600 rpm for 15-60 min to allow the noble metal ions to be fully adsorbed on the surface and edges of the VP / BP heterojunction material to obtain a first mixture; the noble metal precursor solution is prepared by dispersing a noble metal precursor in a mixed solvent; wherein the noble metal precursor is any one of RhCl3, H2PtCl6, AgNO3, and HAuCl4, the mixed solvent is a solution prepared by mixing an organic solvent with deionized water at a volume ratio of 1:5-9, and the organic solvent is any one of methanol, triethanolamine, sodium oxalate, and ethylenediaminetetraacetic acid disodium; the concentration of the noble metal precursor solution is 5-20 mg / mL; S3, performing photochemical reduction reaction on the first mixture obtained in step S2 to selectively deposit noble metal nanoparticles on the edge of the VP / BP heterojunction, to obtain a VP / BP heterojunction composite material loaded with noble metal nanoparticles; comprising the following sub-steps: S3.1, performing vacuum treatment on the first mixture obtained in step S2 at a temperature of 10-20°C and a vacuum degree of 0.01-0.1 bar for 15-30 min to remove dissolved oxygen; S3.2, irradiating the first mixture treated in step S3.1 with a xenon lamp with a wavelength of 420-800 nm for 15-30 min to perform photochemical reduction reaction; after the reaction is completed, the product mixture is filtered and repeatedly washed with deionized water and anhydrous ethanol to remove residual ions; finally, vacuum drying at a temperature of 60-80°C for 10-12 h and a vacuum degree of 0.01-0.1 bar to obtain the target product, a VP / BP heterojunction composite material loaded with noble metal nanoparticles. Embodiment

[0042] A preparation method of a phosphorene-based composite material, comprising the following specific steps: Step 1, mixing bulk VP and BP in a mass ratio of 1:1 in an agate mortar, adding NMP, continuously grinding the mixture of VP and BP with NMP at a feed liquid ratio of 1:20 mg / mL for 30 min to obtain a second mixture; ultrasonic treating the second mixture at a temperature of 8°C and an ultrasonic power of 50 W for 4 h to obtain a first dispersion liquid; first centrifuging the first dispersion liquid at a low speed of 3000 rpm for 10 min to remove un-exfoliated bulk VP and BP, collecting the supernatant, and then centrifuging at a high speed of 11000 rpm for 10 min, collecting the centrifuged sample (supernatant), and vacuum drying at a temperature of 40°C for 12 h at a vacuum degree of 0.01 bar to obtain a VP / BP heterojunction; Step 2, weighing 20 mg of the VP / BP heterojunction obtained in step 1, dispersing in 25 mL of deionized water, and ultrasonic treating for 10 min at an ultrasonic power of 50 W to form a uniform second dispersion liquid; adding 100 μL of RhCl3 solution with a concentration of 10 mg / mL to 10 mL of the second dispersion liquid, and magnetically stirring at 200 rpm for 30 min to allow Rh³⁺ to be fully adsorbed on the surface and edge of the VP / BP heterojunction material to obtain a first mixture; the RhCl3 solution is prepared by dispersing RhCl3 in a mixed solvent prepared by mixing methanol and deionized water in a volume ratio of 1:5; Step 3, first, the first mixture obtained in step 2 is vacuumed at a temperature of 10°C and a vacuum degree of 0.01 bar for 15 min to remove dissolved oxygen; then, a xenon lamp with a wavelength of 420 nm is used for irradiation for 30 min to perform a photochemical reduction reaction, in which process, the P-P dangling bonds exposed at the edge of VP / BP serve as specific nucleation sites to preferentially capture photo-generated electrons, reducing the adsorbed Rh³⁺ to metal Rh0 nanoparticles and forming stable Rh-P bonds; after the reaction is completed, the product mixture is filtered and repeatedly washed with deionized water and anhydrous ethanol to remove residual ions; finally, vacuum drying is performed at a temperature of 80°C and a vacuum degree of 0.01 bar for 10 h to obtain the target product VP / BP-Rh composite material with a loading amount of about 5 wt%. Embodiment

[0043] A preparation method of a phosphorene-based composite material, comprising the following specific steps: Step 1, mix bulk VP and BP in a mass ratio of 1:2 in an agate mortar, add dimethyl sulfoxide, and continuously grind the mixture of VP and BP with dimethyl sulfoxide at a feed liquid ratio of 1:30 mg / mL for 45 min to obtain a second mixture; ultrasonically treat the second mixture at a temperature of 2°C and an ultrasonic power of 30 W for 4 h to obtain a first dispersion liquid; first centrifuge the first dispersion liquid at a low speed of 2000 rpm for 15 min to remove unexfoliated bulk VP and BP, collect the supernatant, and then centrifuge at a high speed of 8000 rpm for 15 min, collect the centrifuged sample (supernatant), and vacuum dry at a temperature of 45°C for 12 h at a vacuum degree of 0.03 bar to obtain a VP / BP heterojunction; Step 2, weigh 20 mg of the VP / BP heterojunction obtained in step 1, disperse in 50 mL of deionized water, and ultrasonically treat for 20 min at an ultrasonic power of 100 W to form a uniform second dispersion liquid; add 100 μL of a RhCl3 solution with a concentration of 6 mg / mL to 12 mL of the second dispersion liquid, and magnetically stir at 400 rpm for 50 min to allow Rh³⁺ to be fully adsorbed on the surface and edge of the VP / BP heterojunction material to obtain a first mixture; the RhCl3 solution is prepared by dispersing RhCl3 in a mixed solvent prepared by mixing triethanolamine and deionized water at a volume ratio of 1:7; Step 3, first, the first mixture obtained in step 2 is vacuumed at a temperature of 15°C and a vacuum degree of 0.01 bar for 15 min to remove dissolved oxygen; then, a xenon lamp with a wavelength of 500 nm is used for irradiation for 30 min to perform a photochemical reduction reaction, in which process, the P-P dangling bonds exposed at the edge of VP / BP serve as specific nucleation sites to preferentially capture photo-generated electrons, reducing the adsorbed Rh³⁺ to metal Rh0 nanoparticles and forming stable Rh-P bonds; after the reaction is completed, the product mixture is filtered and repeatedly washed with deionized water and anhydrous ethanol to remove residual ions; finally, vacuum drying is performed at a temperature of 60°C and a vacuum degree of 0.03 bar for 10 h to obtain the target product VP / BP-Rh composite material with a loading amount of about 3 wt%. Embodiment

[0044] A preparation method of a phosphorene-based composite material, comprising the following specific steps: Step 1, mix bulk VP and BP in a mass ratio of 1:3 in an agate mortar, add isopropyl alcohol, and continuously grind the mixture of VP and BP with isopropyl alcohol at a feed liquid ratio of 1:50 mg / mL for 60 min to obtain a second mixture; ultrasonically treat the second mixture at a temperature of 10°C and an ultrasonic power of 100 W for 2 h to obtain a first dispersion liquid; first centrifuge the first dispersion liquid at a low speed of 5000 rpm for 5 min to remove unexfoliated bulk VP and BP, collect the supernatant, and then centrifuge at a high speed of 15000 rpm for 5 min, collect the centrifuged sample (supernatant), and vacuum dry at a temperature of 60°C for 10 h at a vacuum degree of 0.01 bar to obtain a VP / BP heterojunction; Step 2, weigh 20 mg of the VP / BP heterojunction obtained in step 1, disperse in 100 mL of deionized water, and ultrasonically treat for 30 min at an ultrasonic power of 200 W to form a uniform second dispersion liquid; add 100 μL of RhCl3 solution with a concentration of 15 mg / mL to 20 mL of the second dispersion liquid, and magnetically stir at 600 rpm for 15 min to allow Rh³⁺ to be fully adsorbed on the surface and edge of the VP / BP heterojunction material to obtain a first mixture; the RhCl3 solution is prepared by dispersing RhCl3 in a mixed solvent prepared by mixing ethylenediaminetetraacetic acid disodium salt and deionized water at a volume ratio of 1:9; Step 3, first, the first mixture obtained in step 2 is vacuumed at a temperature of 20℃ and a vacuum degree of 0.1 bar for 15 min to remove dissolved oxygen; then, a xenon lamp with a wavelength of 800 nm is used for irradiation for 30 min to perform a photochemical reduction reaction, in which process, the P-P dangling bonds exposed at the edge of VP / BP serve as specific nucleation sites to preferentially capture photo-generated electrons, reducing the adsorbed Rh³⁺ to metal Rh0 nanoparticles and forming stable Rh-P bonds; after the reaction is completed, the product mixture is filtered and repeatedly washed with deionized water and anhydrous ethanol to remove residual ions; finally, vacuum drying is performed at a temperature of 80℃ and a vacuum degree of 0.1 bar for 12 h to obtain the target product VP / BP-Rh composite material with a loading of about 7 wt%. Embodiment

[0045] A preparation method of a phosphorene-based composite material, comprising the following specific steps: Step 1, mix bulk VP and BP in a mass ratio of 1:1 in an agate mortar, add NMP, and continuously grind the mixture of VP and BP with NMP at a feed liquid ratio of 1:20 mg / mL for 30 min to obtain a second mixture; ultrasonically treat the second mixture at a temperature of 8℃ and an ultrasonic power of 50 W for 4 h to obtain a first dispersion liquid; first centrifuge the first dispersion liquid at a low speed of 3000 rpm for 10 min to remove unexfoliated bulk VP and BP, collect the supernatant, and then centrifuge at a high speed of 11000 rpm for 10 min, collect the centrifuged sample (supernatant), and vacuum dry at a temperature of 40℃ for 12 h at a vacuum degree of 0.01 bar to obtain a VP / BP heterojunction; Step 2, weigh 20 mg of the VP / BP heterojunction obtained in step 1, disperse in 25 mL of deionized water, and ultrasonically treat for 10 min at an ultrasonic power of 50 W to form a uniform second dispersion liquid; add 100 μL of a 10 mg / mL AgNO3 solution to 10 mL of the second dispersion liquid, and magnetically stir at 200 rpm for 30 min to allow Ag⁺ to be fully adsorbed on the surface and edge of the VP / BP heterojunction material to obtain a first mixture; the AgNO3 solution is prepared by dispersing AgNO3 in a mixed solvent of methanol and deionized water in a volume ratio of 1:5; Step 3, first, the first mixture obtained in step 2 is vacuumed at a temperature of 10℃ and a vacuum degree of 0.01 bar for 15 min to remove dissolved oxygen; then, a xenon lamp with a wavelength of 420 nm is used for irradiation for 30 min to perform a photochemical reduction reaction, in which process, the P-P dangling bonds exposed at the edge of VP / BP serve as specific nucleation sites to preferentially capture photo-generated electrons, reducing the adsorbed Ag⁺ into metal Ag0 nanoparticles and forming stable Ag-P bonds; after the reaction is completed, the product mixture is filtered and repeatedly washed with deionized water and anhydrous ethanol to remove residual ions; finally, vacuum drying is performed at a temperature of 80℃ and a vacuum degree of 0.01 bar for 10 h to obtain the target product VP / BP-Ag composite material with a loading amount of about 4 wt%. Embodiment

[0046] A preparation method of a phosphorene-based composite material, comprising the following specific steps: Step 1, mix bulk VP and BP in a mass ratio of 3:1 in an agate mortar, add N,N dimethylformamide, and continuously grind the mixture of VP and BP with N,N dimethylformamide at a solid-liquid ratio of 1:50 mg / mL for 45 min to obtain a second mixture; ultrasonically treat the second mixture at a temperature of 5℃ and an ultrasonic power of 60 W for 3 h to obtain a first dispersion liquid; first centrifuge the first dispersion liquid at a low speed of 4000 rpm for 8 min to remove unexfoliated bulk VP and BP, collect the supernatant, and then centrifuge at a high speed of 12000 rpm for 12 min, collect the centrifuged sample (supernatant), and vacuum dry at a temperature of 55℃ for 10 h at a vacuum degree of 0.05 bar to obtain a VP / BP heterojunction; Step 2, weigh 20 mg of the VP / BP heterojunction obtained in step 1, disperse in 60 mL of deionized water, and ultrasonically treat for 30 min at an ultrasonic power of 150 W to form a uniform second dispersion liquid; add 100 μL of a H2PtCl6 solution with a concentration of 15 mg / mL to 12 mL of the second dispersion liquid, and magnetically stir at 500 rpm for 25 min to allow Pt4⁺ to be fully adsorbed on the surface and edge of the VP / BP heterojunction material to obtain a first mixture; the H2PtCl6 solution is prepared by dispersing H2PtCl6 in a mixed solvent prepared by mixing triethanolamine and deionized water at a volume ratio of 1:7; Step 3, first, the first mixture obtained in step 2 is subjected to vacuum treatment at a temperature of 15°C and a vacuum degree of 0.06 bar for 25 min to remove dissolved oxygen; then, a xenon lamp with a wavelength of 600 nm is used for irradiation for 20 min to perform a photochemical reduction reaction, in which process, the P-P dangling bonds exposed at the edge of VP / BP serve as specific nucleation sites to preferentially capture photo-generated electrons, reduce the adsorbed Pt4⁺ to metal Pt0 nanoparticles, and form stable Pt-P bonds; after the reaction is completed, the product mixture is filtered and repeatedly washed with deionized water and anhydrous ethanol to remove residual ions; finally, vacuum drying is performed at a temperature of 80°C and a vacuum degree of 0.01 bar for 10 h to obtain the target product VP / BP-Pt composite material with a loading of about 6 wt%. Embodiment

[0047] A method for preparing a phosphorene-based composite material, comprising the following specific steps: Step 1, mix bulk VP and BP in a mass ratio of 3:2 in an agate mortar, add methanol, and continuously grind the mixture of VP and BP with methanol at a feed liquid ratio of 1:100 mg / mL for 60 min to obtain a second mixture; ultrasonically treat the second mixture at a temperature of 10°C and an ultrasonic power of 100 W for 2 h to obtain a first dispersion liquid; first centrifuge the first dispersion liquid at a low speed of 5000 rpm for 5 min to remove unexfoliated bulk VP and BP, collect the supernatant, and then centrifuge at a high speed of 15000 rpm for 5 min, collect the centrifuged sample (supernatant), and vacuum dry at a temperature of 60°C for 10 h at a vacuum degree of 0.1 bar to obtain a VP / BP heterojunction; Step 2, weigh 20 mg of the VP / BP heterojunction obtained in step 1, disperse in 60 mL of deionized water, and ultrasonically treat for 10 min at an ultrasonic power of 200 W to form a uniform second dispersion liquid; add 100 μL of a HAuCl4 solution with a concentration of 20 mg / mL to 20 mL of the second dispersion liquid, and magnetically stir at 600 rpm for 15 min to allow Au3⁺ to be fully adsorbed on the surface and edge of the VP / BP heterojunction material to obtain a first mixture; the HAuCl4 solution is prepared by dispersing HAuCl4 in a mixed solvent prepared by mixing ethylenediaminetetraacetic acid disodium salt and deionized water at a volume ratio of 1:9; Step 3: First, the first mixture obtained in Step 2 was subjected to vacuum treatment at 20℃ and 0.1 bar for 15 min to remove dissolved oxygen. Then, it was irradiated with a xenon lamp with a wavelength of 800 nm for 15 min to carry out a photochemical reduction reaction. During this process, the dangling bonds of PP exposed at the edge of VP / BP act as specific nucleation sites, preferentially capturing photogenerated electrons and reducing the adsorbed Au3⁺ to metallic Au0 nanoparticles, forming stable Au-P bonds. After the reaction, the product mixture was filtered and repeatedly washed with deionized water and anhydrous ethanol to remove residual ions. Finally, it was vacuum dried at 80℃ and 0.01 bar for 10 h to obtain the target product VP / BP-Au composite material with a loading of approximately 4 wt%.

[0048] The microstructure and chemical composition of the VP / BP-Rh composite material prepared in Example 1 are examined below.

[0049] Figure 2 (a) Figure 2 (b) Clearly demonstrates the three-component structure of the VP / BP-Rh composite material: the BP substrate, the VP layer covering the surface, and the Rh nanoparticles with edge decoration. Figure 2 (b) is Figure 2 (a) Enlarged view of region 1, Figure 2 (c) is Figure 2 (a) 2 locations Figure 2 (b) Enlarged view of region 3; Figure 2 In the local high-magnification transmission electron microscopy of VP / BP-Rh in (c), obvious VP / BP grain boundaries can be seen, with lattice fringes corresponding to the (200) and (202) crystal planes of VP. Simultaneously, Rh nanoparticles connected by transverse Rh-P bonds are observed at the VP / BP edge, with lattice fringes corresponding to the (100) and (111) crystal planes of Rh. Figure 3 The elemental mapping spectrum in (d) further confirms that the Rh element is uniformly distributed at the edge of VP / BP, which intuitively reflects the feasibility of material preparation.

[0050] exist Figure 4 In the XRD patterns of the VP / BP and VP / BP-Rh heterojunctions, the characteristic diffraction peaks of VP and BP were simultaneously displayed, with no other impurity peaks, indicating that the crystal structures of VP and BP remained intact during the liquid phase exfoliation process, which further demonstrates the successful preparation of the samples.

[0051] exist Figure 5In the diagram, Rh NPs represent Rh nanoparticles. In the Rh 3d spectrum, the peaks with binding energies of 307.3 eV, 312.0 eV, 308.6 eV, and 313.3 eV correspond to Rh0 3d5 / 2, Rh0 3d3 / 2, Rh3+ 3d5 / 2, and Rh3+ 3d3 / 2, respectively. Compared to pure Rh NPs, the intensity ratio of the Rh3+ peak to the Rh0 peak in the VP / BP-Rh heterojunction (Rh3+ / Rh0 = 1.87) is much higher than that of pure Rh NPs (Rh3+ / Rh0 = 0.45). This indicates the presence of more Rh3+ species in VP / BP-Rh, resulting in strong edge-local electric field interactions between Rh and BP. Meanwhile, compared with pure Rh NPs, the Rh 3d species in VP / BP-Rh all showed certain binding energy shifts, which confirmed the strong interfacial electronic interaction between the VP / BP and Rh NP components, proving the successful recombination of VP / BP and Rh NPs.

[0052] Figure 5 The structural model of the VP / BP-Rh composite material prepared in Example 1 was simulated by density functional theory, providing direct evidence for the integrated dual electric field mechanism of VP / BP-Rh. Figure 6 The model diagram and planar slice diagram of differential charge density clearly show that electrons accumulate at the VP / BP interface through the interface PP bond, which can confirm the existence of the phase junction electric field PEF; at the same time, electrons form a charge depletion region around the Rh nanoparticle through the edge P-Rh bond, which can verify the existence of the edge local electric field FEF.

[0053] exist Figure 7 The photocurrent characterization shows that the VP / BP-Rh composite material has a higher photocurrent intensity than VP and VP / BP, proving that the VP / BP-Rh composite material has a more efficient interface charge transfer efficiency during the illumination process. This verifies that the combined effect of the integrated dual electric fields is beneficial to the photoreaction system.

[0054] This invention also discloses the application of the above-mentioned phosphorene-based composite material as a photocatalyst in the treatment of medical wastewater through photocatalytic reactions.

[0055] The photocatalytic reaction described above is a coupled reaction that simultaneously degrades organic pollutants and reduces CO2.

[0056] The aforementioned organic pollutants include, but are not limited to, pharmaceutical and personal care products (PPCPs), endocrine disruptors (EDCs), the antitumor drug 5-fluorouracil (5-FU), and its intermediate degradation products in pharmaceutical wastewater. Preferably, the organic pollutants are recalcitrant organic compounds, such as the nonsteroidal anti-inflammatory drug naproxen (NPX).

[0057] As shown in Figure 8 A photocatalytic system for performing the above photocatalytic reaction, using the phosphorene-based composite material as a catalyst, under irradiation of a light source, and under anoxic or anaerobic conditions.

[0058] The light source of the above photocatalytic system uses a xenon lamp, a mercury lamp or an LED light source to simulate sunlight, AM (Air Mass) 1.5G, and a wavelength range of 200-1100 nm.

[0059] The application of the VP / BP-Rh composite material prepared in Example 1 is evaluated below.

[0060] Test Example As shown in Figure 9 In the photocatalytic reaction device, a 200 mL double-neck heat-resistant glass reactor is used to evaluate the degradation ability of the VP / BP-Rh composite material for organic pollutants in simulated medical wastewater and its performance in simultaneous catalysis of CO2 resource utilization, which includes the following steps: Step one, adsorption equilibrium and anaerobic environment establishment: accurately weigh 20 mg of photocatalyst and disperse it in 40 mL of simulated medical wastewater containing target pollutants (such as 10 mg / L naphthoxin NPX); after ultrasonic dispersion for 5 min, place the reaction solution in the reactor and continuously stir under the system. high-purity nitrogen gas is introduced into the system for 30 min; this process aims to completely remove air from the reaction system and create a strict anoxic reaction environment, while achieving adsorption-desorption equilibrium of pollutant molecules on the catalyst surface; Step two, photocatalytic reaction and product analysis: place the sealed reactor under the simulated sunlight source for irradiation, and maintain stirring during the entire reaction process; after 1 hour of irradiation, perform the following analysis: (1) Gas product analysis: use a gas sampling needle to extract 10 mL of mixed gas from the reactor headspace, and perform qualitative and quantitative analysis by gas chromatography (GC-7890B, Agilent) equipped with a thermal conductivity detector (TCD) and a flame ionization detector (FID), to detect the generated CH4, CO, H2, etc. solar fuels, to evaluate the CO2 resource utilization performance; according to Figure 10 The yield of CO2 reduction products of the VP / BP-Rh composite material after 60 minutes of irradiation is: CO: 4.75 μmol·g-1·h-1, CH4: 6.75 μmol·g-1·h-1, H2: 8.95 μmol·g-1·h-1, indicating that the VP / BP-Rh composite material has high CO2 resource utilization performance.

[0061] (2) Liquid phase pollutants analysis: 10 mL sample was taken from the reaction solution, filtered through a 0.22 μm microporous filter to remove catalyst particles; high performance liquid chromatography (LC-16, Shimadzu) was used to determine the residual concentration of NPX and other characteristic pollutants, and the degradation rate was calculated to evaluate the photocatalytic degradation performance. According to the data in Figure 10 , the degradation rate of VP / BP-Rh composite material on NPX reached 82.7% after 1 hour of light irradiation, and was completely degraded within 4 hours, indicating that the VP / BP-Rh composite material has excellent degradation ability for organic pollutants.

[0062] Step three, pollutant mineralization rate test: total organic carbon analyzer (TOC-L CPH) was used to determine the total amount of organic matter in simulated medical wastewater, and the total amount of organic matter in the solution before and after the reaction was compared to evaluate the mineralization degree of photocatalytic degradation of organic pollutants. According to the auxiliary data in Figure 11 , the degradation trend of NPX and the decrease trend of TOC of VP / BP-Rh composite material during 4 hours of light irradiation were basically the same, indicating that most of the organic pollutants were completely mineralized into CO2 and H2O, further verifying the deep purification ability of VP / BP-Rh composite for medical wastewater.

[0063] Step four, free radical capture experiment: the contribution degree of active species generated in the photocatalytic process was determined by free radical capture experiment; 2 mM inhibitor p-p-benzoquinone (p-BQ) was used to inhibit •O2-, isopropyl alcohol (IPA) was used to inhibit •OH, silver nitrate (AgNO3) was used to inhibit e-, and ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) was used to inhibit h+; according to the data in Figure 12 , after adding different capture agents, the NPX degradation rate changed significantly, among which the addition of hole capture agent could obviously inhibit NPX degradation, when EDTA-2Na was added, the efficiency of photocatalytic degradation of NPX decreased from 82.7% to 28.9%, and the inhibition effect was the most obvious, indicating that h+ was the main degradation active species; in addition, •O2- also had a certain contribution to NPX degradation, which could confirm the key role of holes and superoxide radicals in photocatalytic reaction.

[0064] For the VP / BP-Rh composite material prepared in Example 1, Figure 12 the VP / BP-Ag composite material prepared in Example 4 of b, Figure 12 the VP / BP-Pt composite material prepared in Example 5 of a, Figure 12 the VP / BP-Au composite material prepared in Example 6 of c, in Figure 13It can be seen in the transmission electron microscope that different noble metal nanoparticles are uniformly dispersed at the edge of the VP / BP heterojunction material. At the same time, the reaction system in the application example is tested, and after 60 min of light irradiation, the NPX degradation rate of VP / BP-Pt, VP / BP-Ag and VP / BP-Au is 73.6%, 70.4% and 79.2% respectively, see ​ , all of which exhibit excellent NPX degradation and CO2 resource utilization synergistic catalytic performance.

[0065] Although the present application is specifically demonstrated and introduced in combination with the preferred embodiments, there are many specific implementation methods and approaches for this technical solution. The above description is only the preferred embodiment of the present application, and it should be pointed out that any modification, equivalent replacement, improvement, etc. made by those skilled in the art without departing from the principles of the present application should be included in the protection scope of the present application.

Claims

1. A phosphorene-based composite material, characterized in that: It includes purple Phosphorus / black phosphorus heterojunction and noble metal nanoparticles anchored at the edge of the heterojunction; a phase junction electric field is formed at the interface of the purple phosphorus / black phosphorus heterojunction, and a local edge electric field is formed between the noble metal nanoparticles and the purple phosphorus / black phosphorus heterojunction. The phase junction electric field and the local edge electric field together constitute an integrated dual electric field system.

2. The phosphorene-based composite material according to claim 1, characterized in that: The precious metal nanoparticles are one or more of rhodium, platinum, silver, and gold; and / or the loading of the precious metal nanoparticles is 0.5 to 10 wt% of the total mass of the purple phosphorus / black phosphorus heterojunction.

3. A method for preparing a phosphorene-based composite material, characterized in that: It includes the following steps: S1. Preparation of purple phosphorus / black phosphorus heterojunction, including the following sub-steps: S1.1 Mix the blocky purple phosphorus and black phosphorus, then add a polar organic solvent to fully wet the purple phosphorus and black phosphorus and form a paste-like mixture. Grind continuously to obtain a second mixture. S1.

2. The second mixture obtained in step S1.1 is subjected to ultrasonic treatment to obtain a first dispersion; S1.

3. The first dispersion obtained in step S1.2 is first centrifuged at low speed, and the supernatant is collected. Then it is centrifuged at high speed, the centrifuged sample is collected, and vacuum dried to obtain purple phosphorus / black phosphorus heterojunction. S2. Mix the purple phosphorus / black phosphorus heterojunction obtained in step S1 with the noble metal precursor solution to obtain the first mixture; Includes the following sub-steps: S2.1 Disperse the purple phosphorus / black phosphorus heterojunction obtained in step S1 in deionized water and perform ultrasonic treatment to form a uniform second dispersion. S2.2 Add a noble metal precursor solution to the second dispersion obtained in step S2.1 and perform a magnetic stirring reaction to allow the noble metal ions to be fully adsorbed on the surface and edge of the purple phosphorus / black phosphorus heterojunction material, thereby obtaining a first mixture; S3. First, the first mixture obtained in step S2 is subjected to vacuum treatment; then a photochemical reduction reaction is carried out; after the reaction is completed, the product mixture is filtered, washed, and vacuum dried to allow the noble metal nanoparticles to be selectively deposited at the edge of the purple phosphorus / black phosphorus heterojunction, thus obtaining a purple phosphorus / black phosphorus heterojunction composite material loaded with noble metal nanoparticles, namely a phosphorene-based composite material.

4. The method for preparing the phosphorene-based composite material according to claim 3, characterized in that: It also includes one or more of the following features: (1) In step S1.1, the mass ratio of blocky purple phosphorus to black phosphorus is 1:3 to 3:1; the ratio of the mixture of purple phosphorus and black phosphorus to the polar organic solvent is 1:10 to 100 mg / mL; (2) In step S1.1, the polar organic solvent is one or more of N-methyl-2-pyrrolidone, dimethyl sulfoxide, isopropanol, N,N-dimethylformamide, and methanol; (3) In step S1.1, the grinding time is 10 to 60 minutes; (4) In step S1.2, the temperature is 0 to 10°C, the ultrasonic treatment time is 2 to 6 hours, and the ultrasonic power is 30 to 100W. (5) In step S1.3, the speed of low-speed centrifugation is 2000-5000 rpm and the processing time is 5-15 min; the speed of high-speed centrifugation is 8000-15000 rpm and the processing time is 5-15 min. (6) In step S1.3, the vacuum drying conditions are: vacuum degree of 0.01 to 0.1 bar, temperature of 40 to 60°C, and time of 10 to 12 hours; (7) In step S1.3, the purple phosphorus / black phosphorus heterojunction is a nanosheet structure with a thickness of 1 to 10 nm and a lateral dimension of 0.1 to 2 mm; (8) In step S2.1, the ratio of purple phosphorus / black phosphorus heterojunction to deionized water is 1:1 to 5 mg / mL; (9) In step S2.1, the ultrasonic power is 50-200 W and the ultrasonic treatment time is 10-30 min; (10) In step S2.2, the volume ratio of the noble metal precursor solution to the second dispersion is 1:100 to 200; (11) In step S2.2, the noble metal precursor solution is prepared by dispersing the noble metal precursor in a mixed solvent; wherein, the noble metal precursor is any one of RhCl3, H2PtCl6, AgNO3, HAuCl4, the mixed solvent is a solution prepared by mixing an organic solvent and deionized water at a volume ratio of 1:5 to 9, and the organic solvent is any one of methanol, triethanolamine, sodium oxalate, disodium ethylenediaminetetraacetate; the concentration of the noble metal precursor solution is 5 to 20 mg / mL; (12) In step S2.2, the magnetic stirring conditions are: stirring speed of 200-600 rpm and reaction time of 15-60 min; (13) In step S3, the vacuum treatment conditions are: vacuum degree of 0.01 to 0.1 bar, temperature of 10 to 20°C, and time of 15 to 30 min; (14) In step S3, a light source with a wavelength of 420-800 nm is used to irradiate for 15-30 min to carry out a photochemical reduction reaction; (15) In step S3, the vacuum drying conditions are: vacuum degree of 0.01 to 0.1 bar, temperature of 60 to 80°C, and time of 10 to 12 hours.

5. The application of the phosphorene-based composite material according to claim 1 or 2 as a photocatalyst in the treatment of medical wastewater through photocatalytic reaction.

6. The application according to claim 5, characterized in that: The photocatalytic reaction is a coupled reaction that simultaneously degrades organic pollutants and reduces CO2.

7. The application according to claim 6, characterized in that: The organic pollutants include, but are not limited to, pharmaceuticals and personal care products, endocrine disruptors, the antitumor drug 5-fluorouracil, and its intermediate degradation products in pharmaceutical wastewater.

8. A photocatalytic system that performs the photocatalytic reaction as described in claim 6, characterized in that: It uses the aforementioned phosphorene-based composite material as a catalyst and operates under light source irradiation and in anaerobic or hypoxic conditions.

9. The photocatalytic system according to claim 8, characterized in that: Its light source uses xenon lamps, mercury lamps, or LED light sources to simulate sunlight, AM 1.5G, with a wavelength range of 200–1100 nm.

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