Method for preparing photocatalytic material responding to ultraviolet, visible and near infrared light simultaneously

Abstract

The present application relates to the field of semiconductor materials, and aims to provide a preparation method of a photocatalytic material responding to ultraviolet, visible and near-infrared light simultaneously.The method comprises the following steps: mixing rare earth ion doped bismuth oxybromide, an alcohol solvent and a molybdenum disulfide quantum dot dispersion liquid, continuously stirring and mixing uniformly, and performing a hydrothermal reaction; after the reaction is completed, naturally cooling to room temperature; and after the obtained precipitate is filtered, washed, centrifuged and dried, a molybdenum disulfide quantum dot loaded bismuth oxybromide used as a photocatalytic material is obtained.The present application obtains a certain concentration of oxygen vacancies in the crystal lattice through doping and morphology control means, the oxygen vacancies can effectively promote the separation and migration of photo-generated carriers, and an intermediate energy level is formed in the original energy band structure; while the energy of the ultraviolet and visible light bands in the solar energy is retained, the utilization of near-infrared upconversion light is also expanded.Therefore, the performance of the photocatalyst can be further improved, and the utilization efficiency of light energy in practical application is improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor materials, and particularly to a method for preparing photocatalytic materials that respond simultaneously to ultraviolet, visible and near-infrared light. Background Technology

[0002] Semiconductor photocatalytic materials have promising applications in energy, environment, and other fields. Since the first report of TiO2 photocatalytic water splitting for hydrogen production in 1972, a series of semiconductor photocatalytic materials have attracted much attention and research. However, traditional oxide semiconductors have large band gaps, and in practical applications, they can only utilize 3% to 5% of the energy in the ultraviolet light band of solar energy. With the continuous deepening of research, a large number of novel visible light-responsive semiconductor photocatalytic materials have emerged, which can make good use of the visible light that accounts for about 45% of solar energy. However, the near-infrared light, which accounts for nearly 40% of sunlight, is almost impossible to utilize well. How to further broaden the response range of semiconductor photocatalytic materials into the near-infrared region has gradually become a research hotspot.

[0003] Bismuth oxybromide (Boxybromide) is a novel, highly efficient bismuth-based semiconductor photocatalyst that responds to visible light. Its unique layered structure, characterized by alternating layers of dihalogen atoms and bismuth-oxygen layers, endows it with excellent physicochemical properties. However, the band gap (~2.7 eV) of Boxybromide limits its utilization of visible light, and its utilization of near-infrared light is even more difficult. Furthermore, pure-phase Boxybromide suffers from low quantum efficiency and easy recombination of photogenerated carriers, restricting its practical photocatalytic applications. Currently, methods such as non-metallic ion doping, transition metal ion doping, rare earth ion doping, noble metal deposition, and semiconductor heterostructure construction have been developed to improve its photocatalytic activity. Among these, rare earth ion doping can utilize the unique 4f electron orbitals of rare earth elements to generate upconversion luminescence, thereby converting near-infrared light into the visible light band and expanding the catalyst's light utilization.

[0004] In recent years, with the development and application of rare earth elements, their excellent optical properties have attracted great attention. Due to the high structural matching degree of rare earth ions in bismuth-based semiconductors, their ease of doping and control, rare earth ion doping has become an effective method for expanding the photoresponse range of bismuth-based photocatalytic materials. However, current rare earth ion doping modification preparations are mostly solid-state methods. This method has a short reaction cycle, weak ability to control the microstructure of the catalytic material, and a low specific surface area, which easily leads to the expanded photoresponse range being difficult to utilize due to the low quantum utilization and low active sites of the photocatalytic material itself. Secondly, due to the limited upconversion effect of rare earth elements, single rare earth ion doping is difficult to achieve the expected results in practical near-infrared photocatalytic applications. It is necessary to find suitable sensitizer and activator ions, and further optimize the band structure of bismuth oxybromine itself to better utilize the upconversion effect of rare earth elements.

[0005] Currently, oxide photocatalysts based on oxygen vacancy regulation (such as BiO) 2-x Photocatalysts such as ultrathin layered WO3 have narrow band gaps and good near-infrared spectral absorption. However, the regulation of oxygen vacancies alone will weaken the stability of the material. Moreover, even if a single photocatalytic material can respond to the near-infrared light band, it cannot have good photogenerated carrier separation efficiency. This will limit its near-infrared photocatalytic performance, and further regulation and improvement are still needed in this regard. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology and provide a method for preparing photocatalytic materials that respond to ultraviolet, visible and near-infrared light simultaneously.

[0007] To solve the above-mentioned technical problems, the solution of the present invention is:

[0008] A method for preparing a photocatalytic material that simultaneously responds to ultraviolet, visible, and near-infrared light is provided, comprising the following steps:

[0009] (1) Weigh out bismuth salt precursor and rare earth compound in a molar ratio of 5 to 50:1, add an appropriate amount of deionized water and stir thoroughly to dissolve completely, to obtain a mixed solution A containing bismuth ions and rare earth ions; weigh out bromide precursor in an amount equal to that of bismuth salt precursor, add it to deionized water and stir thoroughly to form a homogeneous bromide solution; add the bromide solution dropwise to mixed solution A and continue stirring for 30 min to form mixed solution B; add sodium hydroxide solution dropwise under stirring conditions to adjust the pH of mixed solution B to 5.5 to 6.2, and continue stirring for 30 min to obtain mixed solution C; transfer mixed solution C to a high-pressure hydrothermal reactor for hydrothermal reaction, and allow it to cool naturally to room temperature after the reaction is complete; after filtration, washing, centrifugation and drying, the obtained precipitate is obtained as rare earth ion-doped bismuth oxybromide;

[0010] (2) Weigh molybdenum disulfide powder and N,N-dimethylformamide at a mass ratio of 1:50 to 100 and mix them to form suspension D; break and disperse suspension D in an ultrasonic crusher; after standing for 5 hours, transfer the supernatant E to a beaker and place it in an oil bath at 145°C for continuous stirring. After stirring, remove it and let it cool naturally; then perform multiple centrifugation and supernatant collection operations to finally obtain a molybdenum disulfide quantum dot dispersion with a solid content of 0.03 to 0.05%.

[0011] (3) Take rare earth ion-doped bismuth oxybromide and alcohol solvent at a mass ratio of 1:50-100, mix them, and then sonicate for 30 min; continue to add molybdenum disulfide quantum dot dispersion, with a mass ratio of molybdenum disulfide quantum dots to rare earth ion-doped bismuth oxybromide of 13:500-1000; continue stirring for 4 h to obtain a uniformly mixed solution F; transfer the mixed solution F to a high-pressure hydrothermal reactor for hydrothermal reaction, and allow it to cool naturally to room temperature after the reaction is completed; after filtration, washing, centrifugation and drying, the obtained precipitate is obtained as bismuth oxybromide supported on molybdenum disulfide quantum dots for use as a photocatalytic material.

[0012] As a preferred embodiment of the present invention, in step (1), the bismuth salt precursor is at least one of bismuth nitrate, bismuth sulfide, and bismuth chloride; the rare earth compound is a mixture of erbium salt and ytterbium salt in a molar ratio of 1:5, wherein the erbium salt is at least one of erbium nitrate and erbium chloride, and the ytterbium salt is at least one of ytterbium nitrate and ytterbium chloride; and the bromide precursor is at least one of potassium bromide, hexadecyltrimethylammonium bromide, and 1-hexadecyl3-methylimidazolium bromide.

[0013] As a preferred embodiment of the present invention, in step (1), the molar concentration of bismuth ions in the mixed solution A is 0.05 to 0.08 mol / L; and the molar concentration of bromide ions in the bromide solution is 0.05 to 0.08 mol / L.

[0014] As a preferred embodiment of the present invention, in step (1), the filling rate of the high-pressure hydrothermal reactor is 60-90%; the temperature of the hydrothermal reaction is controlled at 140-160°C and the time is 12-24h.

[0015] As a preferred embodiment of the present invention, in step (2), the power of ultrasonic crushing and dispersion is 400-500W and the time is 4-8h; the time of continuous stirring in the oil bath is 6-8h.

[0016] As a preferred embodiment of the present invention, in step (2), the centrifugation speed is 12000 r / min, and the supernatant is taken after each centrifugation for 10 min; the operation is repeated 3 times, and the final supernatant is a molybdenum disulfide quantum dot dispersion.

[0017] As a preferred embodiment of the present invention, in step (2), the solid content of the molybdenum disulfide quantum dot dispersion is 0.03-0.05%.

[0018] As a preferred embodiment of the present invention, in step (3), the alcohol solvent is at least one of ethanol, ethylene glycol, and n-butanol.

[0019] As a preferred embodiment of the present invention, in step (3), the filling rate of the high-pressure hydrothermal reactor is 60-90%; the temperature of the hydrothermal reaction is controlled at 120-140°C; and the time is 8-12 hours.

[0020] As a preferred embodiment of the present invention, in steps (1) and (3), the precipitate obtained by filtration is washed three times each with deionized water and anhydrous ethanol, and then centrifuged at a speed of 9000 r / min.

[0021] Description of the invention principle:

[0022] Furthermore, this invention utilizes sodium hydroxide to adjust the pH value of the precursor solution and control the OH content in the solution. - The concentration of the crystals was controlled to regulate the nucleation and growth rate during hydrothermal processes, enabling the crystals to complete the self-assembly process effectively and form a controllable flower-like morphology. Simultaneously, the doping ions created lattice distortion, and sodium hydroxide inhibited growth along the 001 crystal plane, further thinning the nanosheets that make up the nanoflowers. This created oxygen vacancies on the material surface, further enhancing the near-infrared light response of the sample. Ultrasonic cavitation was used to exfoliate multilayered bulk molybdenum disulfide into few-layer molybdenum disulfide, followed by thermal exfoliation to transform it into molybdenum disulfide quantum dots. Electrostatic self-assembly and the formation of metal-anion covalent bonds (Bi-S bonds) under hydrothermal conditions were used to firmly load the molybdenum disulfide quantum dots onto the bismuth oxybromide matrix, constructing a closely contacted heterojunction structure and improving quantum efficiency.

[0023] Due to the matching of the band structure regulated by the prepared materials, the catalyst prepared in this invention can fully utilize the energy of near-infrared light in solar energy while maintaining its responsiveness to visible and ultraviolet light bands.

[0024] Compared with the prior art, the technical effects of the present invention are:

[0025] 1. This invention achieves a certain concentration of oxygen vacancies in the crystal lattice through doping and morphology control. These oxygen vacancies effectively promote the separation and migration of photogenerated carriers and form intermediate energy levels within the original band structure. While retaining the utilization of ultraviolet and visible light energy from solar energy, it also extends to the utilization of near-infrared upconversion light. Therefore, it can further improve the performance of photocatalysts and significantly increase the efficiency of light energy utilization in practical applications.

[0026] 2. This invention employs a hydrothermal preparation method without organic templates and surfactants, achieving controllable preparation of flower-shaped bismuth oxybromide and uniform doping of rare earth elements, thus avoiding the environmental pollution problems that may be caused by traditional organic templates and surfactants.

[0027] 3. This invention utilizes the loading modification of semiconductor quantum dots to simultaneously improve quantum efficiency and light utilization after recombination. This approach is the first of its kind in the industry and provides a direction for future research. Attached Figure Description

[0028] Figure 1 This is a scanning electron microscope (SEM) image of erbium / ytterbium-doped bismuth oxybromine nanoflowers modified with molybdenum disulfide quantum dots as prepared in Example 7.

[0029] Figure 2 High-resolution transmission electron microscopy (TEM) images of erbium / ytterbium-doped bismuth oxybromine nanoflowers modified with molybdenum disulfide quantum dots obtained in Example 7. The left image shows the flower-like structure at lower magnification, while the right image shows the lattice fringes on the material surface at higher magnification. The markings in the right image indicate the interplanar spacing and crystal plane type of the molybdenum disulfide quantum dots and bismuth oxybromine surface visible on the composite material.

[0030] Figure 3 The near-infrared photocatalytic degradation curves of methylene blue dye by erbium / ytterbium-doped bismuth oxybromine nanoflowers, erbium / ytterbium-doped bismuth oxybromine nanoflowers, and pure-phase bismuth oxybromine nanoflowers modified with molybdenum disulfide quantum dots prepared in Example 7 are shown. Detailed implementation method:

[0031] The present invention will now be described in further detail with reference to specific embodiments. These embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the invention, but do not limit the invention in any way.

[0032] Part One: Implementation Details

[0033] The present invention provides a method for preparing a wide-band response photocatalytic material from ultraviolet to near-infrared light, comprising the following steps:

[0034] (1) Weigh out bismuth salt precursor and rare earth compound in a molar ratio of 5–50:1, add an appropriate amount of deionized water and stir thoroughly to dissolve completely, to obtain a mixed solution A containing bismuth ions and rare earth ions, with a bismuth ion molar concentration of 0.05–0.08 mol / L; weigh out bromide precursor in an amount equal to that of bismuth salt precursor, add it to deionized water and stir thoroughly to form a homogeneous bromide solution, with a bromide ion molar concentration of 0.05–0.08 mol / L; add the bromide solution dropwise to mixed solution A and continue stirring for 30 min to form mixed solution B; add sodium hydroxide solution dropwise under stirring conditions to adjust the pH of mixed solution B to 5.5–6.2, and continue stirring for 30 min to obtain mixed solution C; transfer mixed solution C to a high-pressure hydrothermal reactor with a filling rate of 60–90%. Then carry out a hydrothermal reaction, controlling the reaction temperature at 140–160℃ and the time at 12–24 h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature. The precipitate obtained by filtration was washed three times each with deionized water and anhydrous ethanol, and then centrifuged at 9000 r / min. After drying, rare earth ion-doped bismuth oxybromide was obtained.

[0035] Optionally, the bismuth salt precursor is at least one of bismuth nitrate, bismuth sulfide, and bismuth chloride; the rare earth compound is a mixture of erbium salt and ytterbium salt in a molar ratio of 1:5, wherein the erbium salt is at least one of erbium nitrate and erbium chloride, and the ytterbium salt is at least one of ytterbium nitrate and ytterbium chloride; and the bromide precursor is at least one of potassium bromide, hexadecyltrimethylammonium bromide, and 1-hexadecyl3-methylimidazolium bromide.

[0036] (2) Weigh molybdenum disulfide powder and N,N-dimethylformamide at a mass ratio of 1:50-100 and mix them to form suspension D. In an ultrasonic crusher, the suspension D is crushed and dispersed at a power of 400-500W for 4-8 hours. After standing for 5 hours, transfer the supernatant E to a beaker and place it in an oil bath at 145℃ and stir continuously for 6-8 hours. After stirring, remove it and let it cool naturally. Then perform multiple centrifugation and supernatant collection operations: the centrifugation speed is 12000r / min, and the supernatant is collected after each centrifugation for 10 minutes. Repeat this operation 3 times. The final supernatant is a molybdenum disulfide quantum dot dispersion with a solid content of 0.03-0.05%.

[0037] (3) Take rare earth ion-doped bismuth oxybromine and alcohol solvent at a mass ratio of 1:50-100, mix them, and then sonicate for 30 min. The alcohol solvent can be at least one of ethanol, ethylene glycol, and n-butanol. Continue to add molybdenum disulfide quantum dot dispersion, with a mass ratio of molybdenum disulfide quantum dots to rare earth ion-doped bismuth oxybromine of 13:500-1000. Stir continuously for 4 h to obtain a uniformly mixed solution F. Transfer the mixed solution F to a high-pressure hydrothermal reactor for hydrothermal reaction. The filling rate of the high-pressure hydrothermal reactor is 60-90%, the reaction temperature is 120-140℃, and the reaction time is 8-12 h. After the reaction is completed, cool naturally to room temperature. Wash the precipitate obtained by filtration with deionized water and anhydrous ethanol three times each, and then centrifuge at a speed of 9000 r / min. After drying, obtain bismuth oxybromine supported on molybdenum disulfide quantum dots for use as a photocatalytic material.

[0038] Eight examples were used to successfully prepare highly efficient photocatalytic materials that respond to ultraviolet / visible / near-infrared light. The experimental data for each example are shown in Table 1 below.

[0039] Table 1. Data Table of Embodiments

[0040]

[0041]

[0042]

[0043] In Example 2, the molar ratio of potassium bromide to hexadecyltrimethylammonium bromide was 1:1; in Example 5, the molar ratio of potassium bromide to 1-hexadecyl3-methylimidazolium bromide was 1:1; in Example 6, the molar ratio of hexadecyltrimethylammonium bromide to 1-hexadecyl3-methylimidazolium bromide was 1:1; and in Example 8, the molar ratio of potassium bromide, hexadecyltrimethylammonium bromide, and 1-hexadecyl3-methylimidazolium bromide was 2:1:1.

[0044] Part Two: Performance Testing of Photocatalyst Materials (Catalysts)

[0045] 1. The photocatalytic performance of the samples was evaluated by degrading methylene blue under near-infrared light irradiation.

[0046] The light source is a 300W xenon lamp equipped with a total reflection filter (200≤λ≤2500nm) and a near-infrared filter (λ≥760nm). The photocatalytic quartz container is cooled by an external water circulation system to maintain the reaction system temperature at around 25℃, reducing the evaporation of the solution to be degraded and the impact of photothermal effects. In this device, the distance between the xenon lamp and the quartz reaction container is approximately 10cm.

[0047] Take 100 mL of the methylene blue solution to be degraded (10 mg / L), add 50 mg of the prepared photocatalyst, and stir in the dark for 30 min to reach adsorption-desorption equilibrium. Take 4 mL of the liquid, centrifuge to remove the catalyst, and measure the absorption peak intensity of the methylene blue solution using a UV-Vis spectrophotometer, denoted as C0. Then turn on the light source, and every 1 hour, take 4 mL of the liquid, centrifuge to remove the catalyst, and measure the absorption peak intensity of the degraded methylene blue solution using a UV-Vis spectrophotometer, denoted as C0. t Therefore, the degradation rate of methylene blue at that moment can be calculated as P = (C0 - C...). t ) / C0×100%.

[0048] 2. The photocatalytic performance of the samples was evaluated by degrading methylene blue under visible light irradiation.

[0049] The light source is a 300W xenon lamp equipped with a semi-reflective filter (200≤λ≤800nm) and a visible light filter (λ≥400nm). The photocatalytic quartz container is cooled by an external water circulation system to maintain the reaction system temperature at around 25℃, reducing the evaporation of the solution to be degraded and the impact of photothermal effects. In this device, the distance between the xenon lamp and the quartz reaction container is approximately 10cm.

[0050] Take 100 mL of the methylene blue solution to be degraded (10 mg / L), add 50 mg of the prepared photocatalyst, and stir in the dark for 30 min to reach adsorption-desorption equilibrium. Take 4 mL of the liquid, centrifuge to remove the catalyst, and measure the absorption peak intensity of the methylene blue solution using a UV-Vis spectrophotometer, denoted as C0. Then turn on the light source, and every 1 hour, take 4 mL of the liquid, centrifuge to remove the catalyst, and measure the absorption peak intensity of the degraded methylene blue solution using a UV-Vis spectrophotometer, denoted as C0. t Therefore, the degradation rate of methylene blue at that moment can be calculated as P = (C0 - C...). t ) / C0×100%.

[0051] 3. The photocatalytic performance of the samples was evaluated by degrading methylene blue under ultraviolet light irradiation.

[0052] The light source is an ultraviolet xenon lamp; the photocatalytic quartz container is cooled by an external water circulation system to maintain the reaction system temperature at around 25°C, reducing the evaporation of the solution to be degraded and the impact of photothermal effects. In this device, the distance between the xenon lamp and the quartz reaction container is approximately 10 cm.

[0053] Take 100 mL of the methylene blue solution to be degraded (10 mg / L), add 50 mg of the prepared photocatalyst, and stir in the dark for 30 min to reach adsorption-desorption equilibrium. Take 4 mL of the liquid, centrifuge to remove the catalyst, and measure the absorption peak intensity of the methylene blue solution using a UV-Vis spectrophotometer, denoted as C0. Then turn on the light source, and every 1 hour, take 4 mL of the liquid, centrifuge to remove the catalyst, and measure the absorption peak intensity of the degraded methylene blue solution using a UV-Vis spectrophotometer, denoted as C0. t Therefore, the degradation rate of methylene blue at that moment can be calculated as P = (C0 - C...). t ) / C0×100%

[0054] Part Three: Comparison with Existing Catalytic Materials

[0055] 1. The most widely used commercially available material is titanium dioxide photocatalyst (P25). However, P25 has almost no photocatalytic performance under visible and near-infrared light.

[0056] 2. Currently, mainstream single-bismuth semiconductor catalytic materials possess stable chemical properties and suitable conduction and valence band positions, along with good visible light utilization. Among them, bismuth oxyhalides (BiOX) (X = Cl, Br, I) have a unique layered structure, which helps improve their photocatalytic activity. However, they still struggle to achieve satisfactory photocatalytic effects in the near-infrared band. For example, flower-shaped BiOBr photocatalytic materials can achieve a toluene degradation rate of 90% after 300 minutes of ultraviolet irradiation, comparable to the catalytic performance of P25; under visible light irradiation for 300 minutes, the degradation rate is 50%, approximately twice that of P25. Single-bismuth materials exhibit almost no catalytic performance in the near-infrared band.

[0057] 3. Metal sulfides are representative materials in the field of narrow bandgap photocatalysis. Their layered structure gives them tunable bandgap properties. However, the photocatalytic performance of these semiconductor materials is not high, and they are often used in combination with other photocatalysts to improve performance. For example, MoS2 can only achieve a 20% degradation rate of Rhodamine B under visible light within 30 minutes, and the degradation rate of MoS2-modified NaYF4:Yb under near-infrared light is also low. 3+ / Er 3+ The material can achieve a 60% degradation rate of Rhodamine B dye via photocatalysis after 12 hours.

[0058] 4. Regarding photocatalytic performance, the bismuth oxybromine nanoflowers prepared in this invention exhibit a photocatalytic decomposition efficiency of 39% for methylene blue under near-infrared light irradiation by a 300W xenon lamp for 4 hours. In Example 7, due to the doping of rare earth elements and the increased content of surface oxygen vacancies, and through molybdenum sulfide quantum dot loading, the material's near-infrared light response, carrier separation ability, and near-infrared photocatalytic performance were enhanced. After 4 hours of near-infrared light irradiation by a 300W xenon lamp, the photocatalytic decomposition efficiency for methylene blue reached as high as 96%. According to the test results, the catalyst exhibits a photocatalytic decomposition efficiency of 98% for methylene blue under 10 minutes of ultraviolet light irradiation and 99% under 1 hour of visible light irradiation. Therefore, the catalytic material of this invention can simultaneously achieve a broad response from ultraviolet to near-infrared light.

[0059] Part Four: Examples of the Use of Photocatalytic Materials

[0060] In practical applications, the photocatalytic material of this invention is coated onto the reactor wall inside a photocatalytic reactor device. When water containing pollutants flows through the reactor, it comes into full contact with the catalyst coated on the surface and is degraded under light irradiation.

[0061] Finally, it should be noted that the above examples are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of this invention should be considered within the scope of protection of this invention.

Claims

1. A method for preparing a photocatalytic material that simultaneously responds to ultraviolet, visible, and near-infrared light, characterized in that, The specific steps of this preparation method are as follows: (1) Weigh out the bismuth salt precursor and rare earth compound in a molar ratio of 5 to 50:1, add an appropriate amount of deionized water and stir thoroughly to dissolve completely to obtain a mixed solution A containing bismuth ions and rare earth ions; the bismuth salt precursor is at least one of bismuth nitrate and bismuth chloride; the rare earth compound is a mixture of erbium salt and ytterbium salt in a molar ratio of 1:5, the erbium salt is at least one of erbium nitrate and erbium chloride, and the ytterbium salt is at least one of ytterbium nitrate and ytterbium chloride; in the mixed solution A, the molar concentration of bismuth ions is 0.05 to 0.08 mol / L; Weigh out an amount of bromide precursor equal to that of the bismuth salt precursor, add it to deionized water and stir thoroughly to form a homogeneous bromide solution; in the bromide solution, the molar concentration of bromide ions is 0.05~0.08 mol / L; the bromide precursor is at least one of potassium bromide, hexadecyltrimethylammonium bromide, and 1-hexadecyl3-methylimidazolium bromide; add the bromide solution dropwise to mixed solution A and continue stirring for 30 min to form mixed solution B; add sodium hydroxide solution dropwise under stirring conditions to adjust the pH of mixed solution B to 5.5~6.2, and continue stirring for 30 min to obtain mixed solution C; transfer mixed solution C to a high-pressure hydrothermal reactor for hydrothermal reaction, and allow it to cool naturally to room temperature after the reaction is complete; after filtration, washing, centrifugation and drying, the obtained precipitate is obtained as rare earth ion-doped flower-shaped bismuth oxybromide with oxygen vacancies on its surface; (2) Weigh molybdenum disulfide powder and N,N-dimethylformamide at a mass ratio of 1:50~100 and mix them to form suspension D; in an ultrasonic crusher, crush and disperse suspension D; after standing for 5 h, transfer the supernatant E to a beaker and place it in an oil bath at 145 ℃ and stir continuously. After stirring, take it out and let it cool naturally. Then, multiple centrifugation processes and supernatant collection were performed to finally obtain a molybdenum disulfide quantum dot dispersion with a solid content of 0.03~0.05%. (3) Take rare earth ion-doped flower-shaped bismuth oxybromide and alcohol solvent at a mass ratio of 1:50~100, mix them and sonicate for 30 min; continue to add molybdenum disulfide quantum dot dispersion, the mass ratio of molybdenum disulfide quantum dots to rare earth ion-doped flower-shaped bismuth oxybromide is 13:500~1000; continue stirring for 4 h to obtain a uniformly mixed solution F; transfer the mixed solution F to a high-pressure hydrothermal reactor for hydrothermal reaction, and cool it naturally to room temperature after the reaction is completed; after filtration, washing, centrifugation and drying, the obtained precipitate is obtained as molybdenum disulfide quantum dot-supported bismuth oxybromide used as a photocatalytic material.

2. The method according to claim 1, characterized in that, In step (1), the filling rate of the high-pressure hydrothermal reactor is 60-90%; the temperature of the hydrothermal reaction is controlled at 140-160 ℃ and the time is 12-24 h.

3. The method according to claim 1, characterized in that, In step (2), the power of ultrasonic crushing and dispersion is 400~500 W and the time is 4~8 h; the time of continuous stirring in the oil bath is 6~8 h.

4. The method according to claim 1, characterized in that, In step (2), the centrifugation speed is 12000 r / min, and the supernatant is taken after each centrifugation for 10 min; this operation is repeated 3 times, and the final supernatant is a molybdenum disulfide quantum dot dispersion.

5. The method according to claim 1, characterized in that, In step (3), the alcohol solvent is at least one of ethanol, ethylene glycol, and n-butanol.

6. The method according to claim 1, characterized in that, In step (3), the filling rate of the high-pressure hydrothermal reactor is 60-90%; the temperature of the hydrothermal reaction is controlled at 120-140℃; and the time is 8-12 h.

7. The method according to claim 1, characterized in that, In steps (1) and (3), the precipitate obtained by filtration is washed three times each with deionized water and anhydrous ethanol, and then centrifuged at a speed of 9000 r / min.

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