Indium phosphide quantum dot-bismuth tungstate composite material and its preparation method and application

Abstract

This invention discloses an indium phosphide quantum dot-bismuth tungstate composite material, its preparation method, and its application, relating to the field of photocatalytic materials technology. The preparation method includes the following steps: Indium precursor is added to oleylamine and mixed; the mixture is gradually heated and kept at a constant temperature under nitrogen protection; then, tris(diphenylphosphine) is added at 170-190°C to react and obtain indium phosphide quantum dots; bismuth nitrate is dispersed in water, and hexadecyltrimethylammonium bromide and sodium tungstate are added sequentially, followed by a hydrothermal reaction to obtain bismuth tungstate microflowers; indium phosphide quantum dots and bismuth tungstate microflowers are added to deionized water, mixed evenly, heated to react, cooled to room temperature, washed, and dried to obtain the indium phosphide quantum dot-bismuth tungstate composite material. This invention also discloses the indium phosphide quantum dot-bismuth tungstate composite material prepared by the above method and its application. This composite material has the function of photocatalytic H2O2 production and has significant application value in the treatment of coking wastewater.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic materials technology, specifically to an indium phosphide quantum dot-bismuth tungstate composite material, its preparation method, and its application. Background Art

[0002] Hydrogen peroxide (H2O2) is a clean energy source that can be broken down into water and oxygen, making it an environmentally friendly option for a variety of applications, including bleaching, green chemical synthesis, and wastewater treatment. Photocatalytic synthesis of H2O2 from O2 and H2O is an economical, clean, and green method with broad application potential. However, most photocatalysts reported to date require a sacrificial agent (ethanol or methanol) to quench the hydrogen peroxide. + This also promotes the reduction of O2 to H2O2. This requirement increases the cost of H2O2 production and hinders the development of photocatalysis technology. Therefore, developing new and environmentally friendly methods for H2O2 production is crucial.

[0003] Quantum dots (QDs), with dimensions of only a few nanometers in all three dimensions, have attracted considerable interest as specialized semiconductor photocatalysts due to their unique physical properties. Various quantum dots, such as ZnS quantum dots, carbon quantum dots, and CdSe quantum dots, have been identified as effective photocatalysts for H₂O₂ production. For example, without the use of sacrificial agents, the H₂O₂ yield of heterostructured ZnS and carbon quantum dot nanofibers reached 2.89 mmol·g⁻¹. -1 ·h -1 Indium phosphide (InP) quantum dots exhibit significant photocatalytic activity. However, the small size of quantum dots presents challenges for the separation and recovery of photocatalysts. Furthermore, their performance remains insufficient for practical applications due to low charge separation efficiency. Therefore, developing new systems to improve charge separation efficiency and stability is crucial. Indium phosphide (InP) quantum dots are a promising alternative for directly converting solar energy into fuel, making them ideal for environmental and biological applications. However, although InP quantum dots have been used in research on photoelectrodes and solar cells, their photocatalytic properties have been rarely studied. To our knowledge, the production of H2O2 using an InP quantum dot-based photocatalytic system without the addition of sacrificial agents has not yet been reported.

[0004] In recent years, bismuth tungstate (Bi₂WO₆) has been widely used in photocatalysis as an excellent visible light photocatalyst due to its high visible light activity, suitable band gap (2.8 eV), and layered tungsten oxide structure. Bi₂WO₆, as a superior semiconductor, has become a hot topic in photocatalysis research due to its stable crystal structure, high quantum efficiency, and excellent energy utilization. However, Bi₂WO₆ has some drawbacks, such as limited surface defects and rapid recombination of the photogenerating support, which restricts its photocatalytic performance. To overcome these challenges, considerable efforts have been made, such as nanostructure modification, surface engineering, and heterojunction / homogeneous junction design. In recent years, the use of quantum dots to modify Bi₂WO₆ to enhance its photocatalytic activity has received widespread attention. For example, Bi₂WO₆ / Cu₂O QDs composites have been shown to improve photocatalytic performance in the visible light range. Furthermore, Zn₂SnO₄ QDs-modified Bi₂WO₆ nanocomposites have been prepared, improving the photocatalytic degradation efficiency of acetone. Building upon this foundation, researchers successfully synthesized a Bi₂WO₆ / CdS QDs composite material and tested its photocatalytic activity by degrading Rhodamine B (RhB) and tetracycline hydrochloride (TC) and reducing Cr (VI) in aqueous solution. However, to our knowledge, the application of QDs-modified Bi₂WO₆ in the photocatalytic production of H₂O₂ has not been reported. This undeveloped novel material provides a promising avenue for future research. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide an indium phosphide quantum dot-bismuth tungstate composite material, its preparation method, and its application. This composite material has the function of photocatalytic H2O2 production and has significant application value in the treatment of coking wastewater degradation.

[0006] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A method for preparing indium phosphide quantum dot-bismuth tungstate composite material is provided, comprising the following steps:

[0007] (1) Add the indium precursor to oleylamine and mix. Then, under nitrogen protection, gradually heat to 110-130℃ and keep warm for a period of time. Then heat to 170-190℃ and add tris(dimethylamino)phosphine to react and obtain indium phosphide quantum dots.

[0008] (2) Bismuth nitrate was dispersed in deionized water, and hexadecyltrimethylammonium bromide and sodium tungstate were added in sequence and stirred evenly. Then, a hydrothermal reaction was carried out to obtain bismuth tungstate micro-flowers.

[0009] (3) Add the indium phosphide quantum dots obtained in step (1) and the bismuth tungstate microflowers obtained in step (2) to deionized water and mix them evenly. Then heat the mixture to react, cool it to room temperature, wash and dry it to obtain the indium phosphide quantum dot-bismuth tungstate composite material.

[0010] Furthermore, in step (1), the indium precursor is indium chloride.

[0011] Furthermore, in step (1), the molar volume ratio of indium precursor, oleylamine and tris(dimethylamino)phosphine is 0.2-0.3 mmol: 10 mL: 0.5 mL.

[0012] Furthermore, in step (1), the temperature is maintained for 50-70 minutes; the reaction is carried out for 20-40 minutes.

[0013] Furthermore, in step (2), the ratio of bismuth nitrate, hexadecyltrimethylammonium bromide and sodium tungstate is 1-3 mmol: 0.08-0.12 g: 0.8-1.2 mmol.

[0014] Bismuth nitrate and sodium tungstate can also be used in their hydrates.

[0015] Furthermore, in step (2), the hydrothermal reaction is carried out at a temperature of 170-190℃ for 10-15 hours.

[0016] Furthermore, in step (3), the mass ratio of indium phosphide quantum dots to bismuth tungstate microflowers is 0.5-5:1.

[0017] Furthermore, in step (3), the reaction is heated at 170-190℃ for 10-15 hours.

[0018] The present invention also provides an indium phosphide quantum dot-bismuth tungstate composite material prepared by the above-mentioned method for preparing the indium phosphide quantum dot-bismuth tungstate composite material.

[0019] This invention also provides the application of the above-mentioned indium phosphide quantum dot-bismuth tungstate composite material in photocatalytic hydrogen peroxide production.

[0020] The present invention also provides the application of the above-mentioned indium phosphide quantum dot-bismuth tungstate composite material in the treatment of coking wastewater.

[0021] The present invention has the following beneficial effects:

[0022] 1. The InP / Bi2WO6 composite material of this invention can photocatalytically generate H2O2 in pure water without the use of a sacrificial agent. Furthermore, InP / Bi2WO6 possesses a wide specific surface area, providing additional reaction sites for the photocatalytic process. For the InP / Bi2WO6 photocatalyst, the composite material exhibits an enhanced photocatalytic H2O2 production yield, reaching as high as 17.45 mmol·g. -1 ·h-1 These figures are 90.8 times and 53.6 times that of pure InP quantum dots and pure Bi2WO6, respectively.

[0023] 2. The H2O2 generated by the InP / Bi2WO6 photocatalysis of this invention can be used to remove chemical oxygen demand (COD) from actual coking wastewater, degrading the COD concentration of coking wastewater (around 150 mg / L) to below the national standard, thus paving the way for the application of photocatalytic systems in the environmental and energy fields. Attached Figure Description

[0024] Figure 1 XRD patterns of InP, Bi2WO6 and 3InP / Bi2WO6 obtained in Example 3;

[0025] Figure 2 The images show the scanning electron microscope and transmission electron microscope observations of InP, Bi2WO6 and 3InP / Bi2WO6 prepared in Example 3.

[0026] Figure 3 The graph shows the test results of InP / Bi2WO6 photocatalytic H2O2 production under pure water conditions;

[0027] Figure 4 Figure 1 shows the test results of H2O2 production by InP / Bi2WO6 photocatalysis under industrial water and tap water conditions;

[0028] Figure 5 The graph shows the COD test results of InP / Bi2WO6 photocatalytic H2O2 degradation in coking wastewater. Detailed Implementation

[0029] The principles and features of this invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0030] Example 1

[0031] An indium phosphide quantum dot-bismuth tungstate composite material (0.5InP / Bi2WO6) is prepared by the following steps:

[0032] (1) Add 0.25 mmol of indium chloride to 10 mL of oleylamine and mix. Then, under nitrogen protection, gradually heat to 120 °C and keep warm for 60 min. Then heat to 180 °C and add 0.5 mL of tris(dimethylamino)phosphine and react for 30 min to obtain indium phosphide quantum dots (InP).

[0033] (2) Disperse 2 mmol of bismuth nitrate pentahydrate in deionized water, add 0.1 g of hexadecyltrimethylammonium bromide and 1 mmol of sodium tungstate dihydrate in sequence and stir until uniform. Then, perform hydrothermal reaction at 180°C for 12 h to obtain bismuth tungstate micro-flowers (Bi2WO6).

[0034] (3) The indium phosphide quantum dots obtained in step (1) and the bismuth tungstate microflowers obtained in step (2) were added to deionized water at a mass ratio of 0.5:1 and mixed evenly. Then, the mixture was heated at 180°C for 12 hours and cooled to room temperature. After washing and drying, the indium phosphide quantum dot-bismuth tungstate composite material was obtained.

[0035] Example 2

[0036] An indium phosphide quantum dot-bismuth tungstate composite material (1InP / Bi2WO6) is prepared by the following steps:

[0037] (1) Add 0.25 mmol of indium chloride to 10 mL of oleylamine and mix. Then, under nitrogen protection, gradually heat to 120 °C and keep warm for 60 min. Then heat to 180 °C and add 0.5 mL of tris(dimethylamino)phosphine and react for 30 min to obtain indium phosphide quantum dots.

[0038] (2) Disperse 2 mmol of bismuth nitrate pentahydrate in deionized water, add 0.1 g of hexadecyltrimethylammonium bromide and 1 mmol of sodium tungstate dihydrate in sequence and stir until homogeneous. Then, perform hydrothermal reaction at 180°C for 12 h to obtain bismuth tungstate micro-flowers.

[0039] (3) The indium phosphide quantum dots obtained in step (1) and the bismuth tungstate microflowers obtained in step (2) are added to deionized water at a mass ratio of 1:1 and mixed evenly. Then, the mixture is heated at 180°C for 12 hours, cooled to room temperature, washed and dried to obtain the indium phosphide quantum dot-bismuth tungstate composite material.

[0040] Example 3

[0041] An indium phosphide quantum dot-bismuth tungstate composite material (3InP / Bi2WO6) is prepared by the following steps:

[0042] (1) Add 0.25 mmol of indium chloride to 10 mL of oleylamine and mix. Then, under nitrogen protection, gradually heat to 120 °C and keep warm for 60 min. Then heat to 180 °C and add 0.5 mL of tris(dimethylamino)phosphine and react for 30 min to obtain indium phosphide quantum dots.

[0043] (2) Disperse 2 mmol of bismuth nitrate pentahydrate in deionized water, add 0.1 g of hexadecyltrimethylammonium bromide and 1 mmol of sodium tungstate dihydrate in sequence and stir until homogeneous. Then, perform hydrothermal reaction at 180°C for 12 h to obtain bismuth tungstate micro-flowers.

[0044] (3) The indium phosphide quantum dots obtained in step (1) and the bismuth tungstate microflowers obtained in step (2) were added to deionized water at a mass ratio of 3:1 and mixed evenly. Then, the mixture was heated at 180°C for 12 hours and cooled to room temperature. After washing and drying, the indium phosphide quantum dot-bismuth tungstate composite material was obtained.

[0045] Example 4

[0046] An indium phosphide quantum dot-bismuth tungstate composite material (5InP / Bi2WO6) is prepared by the following steps:

[0047] (1) Add 0.25 mmol of indium chloride to 10 mL of oleylamine and mix. Then, under nitrogen protection, gradually heat to 120 °C and keep warm for 60 min. Then heat to 180 °C and add 0.5 mL of tris(dimethylamino)phosphine and react for 30 min to obtain indium phosphide quantum dots.

[0048] (2) Disperse 2 mmol of bismuth nitrate pentahydrate in deionized water, add 0.1 g of hexadecyltrimethylammonium bromide and 1 mmol of sodium tungstate dihydrate in sequence and stir until homogeneous. Then, perform hydrothermal reaction at 180°C for 12 h to obtain bismuth tungstate micro-flowers.

[0049] (3) The indium phosphide quantum dots obtained in step (1) and the bismuth tungstate microflowers obtained in step (2) are added to deionized water at a mass ratio of 5:1 and mixed evenly. Then, the mixture is heated at 180°C for 12 hours and cooled to room temperature. After washing and drying, the indium phosphide quantum dot-bismuth tungstate composite material is obtained.

[0050] Example 5

[0051] An indium phosphide quantum dot-bismuth tungstate composite material is prepared by the following steps:

[0052] (1) Add 0.2 mmol of indium chloride to 10 mL of oleylamine and mix. Then, under nitrogen protection, gradually heat to 110 °C and keep warm for 50 min. Then heat to 170 °C and add 0.5 mL of tris(dimethylamino)phosphine and react for 20 min to obtain indium phosphide quantum dots.

[0053] (2) Disperse 1 mmol of bismuth nitrate pentahydrate in deionized water, add 0.08 g of hexadecyltrimethylammonium bromide and 0.8 mmol of sodium tungstate dihydrate in sequence and stir until homogeneous. Then, perform hydrothermal reaction at 170 °C for 10 h to obtain bismuth tungstate micro-flowers.

[0054] (3) The indium phosphide quantum dots obtained in step (1) and the bismuth tungstate microflowers obtained in step (2) were added to deionized water at a mass ratio of 0.5:1 and mixed evenly. Then, the mixture was heated at 170°C for 10 hours and cooled to room temperature. After washing and drying, the indium phosphide quantum dots-bismuth tungstate composite material was obtained.

[0055] Example 6

[0056] An indium phosphide quantum dot-bismuth tungstate composite material (0.5InP / Bi2WO6) is prepared by the following steps:

[0057] (1) Add 0.3 mmol of indium chloride to 10 mL of oleylamine and mix. Then, under nitrogen protection, gradually heat to 130 °C and keep warm for 70 min. Then heat to 190 °C and add 0.5 mL of tris(dimethylamino)phosphine and react for 40 min to obtain indium phosphide quantum dots.

[0058] (2) Disperse 3 mmol of bismuth nitrate pentahydrate in deionized water, add 0.12 g of hexadecyltrimethylammonium bromide and 1.2 mmol of sodium tungstate dihydrate in sequence and stir until homogeneous. Then, perform hydrothermal reaction at 190 °C for 15 h to obtain bismuth tungstate micron flowers.

[0059] (3) The indium phosphide quantum dots obtained in step (1) and the bismuth tungstate microflowers obtained in step (2) are added to deionized water at a mass ratio of 5:1 and mixed evenly. Then, the mixture is heated at 190°C for 15 hours and cooled to room temperature. After washing and drying, the indium phosphide quantum dot-bismuth tungstate composite material is obtained.

[0060] Experimental Example 1

[0061] (1) The phase structures of indium phosphide quantum dots (InP), bismuth tungstate microflowers (Bi2WO6), and indium phosphide quantum dot-bismuth tungstate composite material (3InP / Bi2WO6) prepared in Example 3 were characterized by XRD, and the results are as follows: Figure 1 As shown.

[0062] The diffraction peaks of InP at 26.3°, 30.4°, 43.6°, 51.6°, 54.1°, and 63.4° can be attributed to the (111), (200), (220), (311), (222), and (400) crystal planes of InP. All diffraction peaks of the synthesized InP quantum dots match well with the PDF#32-0452 card, with no additional high-crystallinity impurity peaks, demonstrating the successful synthesis of pure-phase InP. Similarly, the diffraction peaks at 28.31°, 32.90°, 47.16°, 55.89°, and 58.61° are attributed to the (131), (200), (202), (133), and (182) crystal planes of Bi2WO6. The peak positions are consistent with the Bi2WO6 PDF#39-0256 standard card. According to the XRD pattern of the InP / Bi2WO6 composite material, obvious peaks were observed in both InP and Bi2WO6, with no additional peaks, confirming the successful preparation of the composite material.

[0063] (2) The morphologies of Bi2WO6, InP, and 3InP / Bi2WO6 prepared in Example 3 were observed by scanning electron microscopy and transmission electron microscopy. The results are as follows: Figure 2 As shown, ac represents the SEM, TEM, and HRTEM images of Bi2WO6, d represents the SAED image of Bi2WO6, e represents the HRTEM image of InP, f represents the HRTEM image of the 3InP / Bi2WO6 composite material, and Bi, W, O, In, and P represent the corresponding EDS element mappings.

[0064] Depend on Figure 2 Bi₂WO₆ exhibits petal-like clusters composed of nanosheets with an average diameter of 1 μm. Clearly, this structure possesses a large surface area containing numerous active sites. TEM images of Bi₂WO₆ show that its edges are square laminar flows with dimensions of approximately 50-100 nm, and HRTEM images further reveal its internal structure. The lattice spacing corresponding to the (200) plane of Bi₂WO₆ is 0.273 nm. Furthermore, the well-dispersed bright spots in the SAED mode of Bi₂WO₆ indicate the presence of a highly ordered crystal structure within the sample. HRTEM characterization of InP showed that the prepared InP quantum dots were spherical nanoparticles with a lattice spacing of 0.33 nm, matching the (111) plane of InP. TEM images of the 3InP / Bi2WO6 composite material revealed translucent nanosheets encapsulated by numerous nanoparticles. Furthermore, lattice fringes with a lattice spacing of 0.273 nm, belonging to the (200) plane of Bi2WO6, were observed. Elemental mapping of 3InP / Bi2WO6 showed the presence of Bi, W, O, In, and P, confirming the successful preparation of the composite material.

[0065] Experimental Example 2

[0066] (1) The photocatalytic performance of the indium phosphide quantum dot-bismuth tungstate composite materials prepared in Examples 1-4 was tested under pure water conditions with xenon lamp irradiation (300W, λ>420nm) (no sacrificial agent added, 20mg composite material, 50 mL H2O+O2). The results are as follows: Figure 3 As shown in the figure. The results show that the indium phosphide quantum dot-bismuth tungstate composite material of the present invention exhibits enhanced photocatalytic H2O2 yield, of which the maximum yield of 3InP / Bi2WO6 reaches 17.45 mmol·g. -1 ·h -1 The concentrations were 90.8 times and 53.6 times that of pure InP and Bi2WO6, respectively.

[0067] (2) The efficiency of InP / Bi2WO6 was also demonstrated in tap water and industrial wastewater, as shown in the results. Figure 4 As shown, although the synthesis efficiency of H2O2 decreases in complex systems, the synthesis efficiency of the photocatalyst in industrial wastewater and tap water is 3.38 mmol·g⁻¹. -1 ·h -1 and 13.31 mmol·g -1 ·h -1 .

[0068] (3) The above experiments show that InP / Bi2WO6 has great potential as an innovative and green method for producing H2O2 using H2O, O2, and light. To study the effect of photocatalytic H2O2 production, the synthesized H2O2 was used to degrade the chemical oxygen demand (COD) in coking wastewater. The results are as follows: Figure 5 As shown, after simulated sunlight irradiation, the photodegradation efficiency of COD reaches approximately 60%. The COD concentration was 150 mg / L. -1 Reduced to 60 mg·L -1 It is far below the emission standards of the coking industry.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an indium phosphide quantum dot-bismuth tungstate composite material, characterized in that, Includes the following steps: (1) Add the indium precursor to oleylamine and mix. Then, under nitrogen protection, gradually heat to 110-130℃ and keep warm for a period of time. Then heat to 170-190℃ and add tris(dimethylamino)phosphine to react and obtain indium phosphide quantum dots. (2) Bismuth nitrate was dispersed in deionized water, and hexadecyltrimethylammonium bromide and sodium tungstate were added in sequence and stirred evenly. Then, a hydrothermal reaction was carried out to obtain bismuth tungstate micro-flowers. (3) Add the indium phosphide quantum dots obtained in step (1) and the bismuth tungstate microflowers obtained in step (2) to deionized water and mix them evenly. Then heat the mixture at 170-190℃ for 10-15h, cool it to room temperature, wash and dry it to obtain the indium phosphide quantum dot-bismuth tungstate composite material.

2. The preparation method of the indium phosphide quantum dot-bismuth tungstate composite material as described in claim 1, characterized in that, In step (1), the indium precursor is indium chloride.

3. The preparation method of the indium phosphide quantum dot-bismuth tungstate composite material as described in claim 1, characterized in that, In step (1), the molar volume ratio of the indium precursor, oleylamine and tris(dimethylamino)phosphine is 0.2-0.3 mmol: 10 mL: 0.5 mL.

4. The preparation method of the indium phosphide quantum dot-bismuth tungstate composite material as described in claim 1, characterized in that, In step (1), keep warm for 50-70 minutes; react for 20-40 minutes.

5. The method for preparing the indium phosphide quantum dot-bismuth tungstate composite material as described in claim 1, characterized in that, In step (2), the ratio of bismuth nitrate, hexadecyltrimethylammonium bromide and sodium tungstate is 1-3 mmol: 0.08-0.12 g: 0.8-1.2 mmol.

6. The method for preparing the indium phosphide quantum dot-bismuth tungstate composite material as described in claim 1, characterized in that, In step (3), the mass ratio of indium phosphide quantum dots to bismuth tungstate microflowers is 0.5-5:

1.

7. The indium phosphide quantum dot-bismuth tungstate composite material prepared by the preparation method of any one of claims 1-6.

8. The application of the indium phosphide quantum dot-bismuth tungstate composite material according to claim 7 in photocatalytic hydrogen peroxide production.

9. The application of the indium phosphide quantum dot-bismuth tungstate composite material according to claim 7 in the treatment of coking wastewater.

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