Graphdiyne / bismuth oxybromide heterojunction photocatalyst as well as preparation method and application thereof
The preparation of graphiteyne/bromobis bromine oxide heterojunction photocatalysts through hydrothermal method has solved the problem of poor interface compatibility of heterojunction photocatalysts in the prior art, achieved efficient photocatalytic CO2 reduction, and significantly improved material stability and reactivity.
Patent Information
- Application Number
- CN202510198399.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-22
- Publication Date
- 2025-05-27
AI Technical Summary
In the prior art, when constructing heterojunction photocatalysts, the interface compatibility of the two substances is poor, resulting in easy recombination of photogenerated carriers, low separation efficiency, and poor reduction effect of the photocatalyst.
The bismuth source and bromine source were dissolved in water by hydrothermal method, and graphite alkyne was added to form a graphite alkyne/bromobis bismuth oxide heterojunction photocatalyst in which bismuth bromine oxide nanosheets were composited with graphite alkyne.
Through the design of heterojunction structure, the separation and transfer of photogenerated charges are optimized, the light absorption range of the photocatalyst is broadened, the photocatalytic efficiency is significantly improved, and the stability of the material is enhanced.
Smart Images
Figure CN120037945A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of photocatalytic reduction of carbon dioxide by nanomaterials, and particularly relates to a graphdiyne / bismuth oxybromide heterojunction photocatalyst, a preparation method thereof, and an application thereof. Background Art
[0002] With the development of society, environmental problems have attracted more and more attention. The combustion of fossil fuels releases a large amount of carbon dioxide. Photocatalytic technology is used to convert carbon dioxide into high-value fuels.
[0003] Traditional photocatalysts include TiO 2 , ZnO, and CeO 2 etc. Although they exhibit excellent photocatalytic activity, their absorption ability in the visible light region is poor, which limits their practical applications. Bismuth oxybromide has a narrow bandgap and a unique layered structure, which promotes the formation of an internal electric field, accelerates the diffusion and separation of photoinduced carriers, and has broad application prospects. It is a promising photocatalytic material. However, due to the insufficient visible light capture ability caused by a wide bandgap, low migration efficiency of photoinduced carriers, and too fast recombination rate, the photocatalytic efficiency of bismuth oxybromide is still low.
[0004] The prior art modifies bismuth oxybromide by ion doping, sensitization technology, and constructing heterostructures to improve the photocatalytic performance of bismuth oxybromide. Ion doping is to introduce defects on bismuth oxybromide to capture photogenerated electrons or holes, thereby improving the photocatalytic efficiency of bismuth oxybromide; sensitization technology is to adsorb photoactive compounds on the surface of the photocatalyst bismuth oxybromide to expand the light absorption range, effectively utilize visible light, and improve the visible light capture ability; constructing heterostructures is to improve the photocatalytic reduction performance of bismuth oxybromide by increasing the separation efficiency of photoinduced carriers.
[0005] The prior art has constructed a hydrotalcite / bismuth oxybromide heterojunction and a bismuthyl iodide / bismuth oxybromide heterojunction. However, in the process of constructing the heterojunction photocatalyst in the prior art, two substances are synthesized separately and then compounded, resulting in poor interfacial compatibility between the two substances, leading to easy recombination of photoinduced carriers in the formed heterojunction and low separation efficiency, and poor reduction effect of the photocatalyst. Summary of the Invention
[0006] In order to solve the above technical problems, the present invention provides a graphdiyne / bismuth oxybromide heterojunction photocatalyst, a preparation method thereof, and an application thereof.
[0007] The first object of the present invention is to provide a preparation method of a graphdiyne / bismuth oxybromide heterojunction photocatalyst, including the following steps:
[0008] Dissolve the bismuth source and bromine source in water, and then add graphdiyne. Adopt the hydrothermal method to enable the bismuth ions provided by the bismuth source to react with the bromine ions provided by the bromine source, and form bismuth oxybromide nanosheets on the surface of graphdiyne, so as to obtain a graphdiyne / bismuth oxybromide heterojunction photocatalyst formed by the composite of graphdiyne and bismuth oxybromide nanosheets.
[0009] It should be noted that bismuth oxybromide is a semiconductor material with a layered structure, having a wide light absorption range, especially strong absorption ability in the visible light region. Moreover, bismuth oxybromide has a strong ability to generate photogenerated electrons and holes, but its photogenerated electron-hole pairs are prone to recombination, which limits its photocatalytic performance. Graphdiyne is a two-dimensional carbon material with a two-dimensional network structure hybridized by sp and sp 2 Its unique structure endows it with rich chemical bonds, excellent carrier mobility, good electrical properties, conductivity and stability. In addition, graphdiyne has good light absorption ability in the visible light region, can effectively capture photons and generate photogenerated carriers; the two-dimensional structure of graphdiyne provides a large number of reactive sites, which can effectively transfer electrons and promote the photocatalytic reaction.
[0010] In the present invention, by compounding bismuth oxybromide and graphdiyne, a heterojunction structure is formed. The interface between graphdiyne and bismuth oxybromide can effectively promote the transfer of electrons, reducing the recombination probability of photogenerated electrons and holes. The formation of the heterojunction can optimize the energy band alignment between the two components, promote the transfer of electrons from bismuth oxybromide to graphdiyne, and enhance the separation efficiency of electron-hole pairs. And the heterojunction design helps to reduce the recombination of photogenerated electrons and holes, improve the utilization efficiency of photogenerated charges, and enhance the photocatalytic activity. In addition, graphdiyne has a wide light absorption range and can absorb more ultraviolet light and visible light. The introduction of graphdiyne significantly enhances the visible light absorption ability of the composite material, and the wide absorption range enables more photogenerated electrons and holes to be excited, increasing the initial carrier concentration of the photocatalytic reaction. At the same time, the high conductivity of graphdiyne ensures that photogenerated electrons can quickly transfer from bismuth oxybromide to graphdiyne, preventing the recombination of electrons and holes inside bismuth oxybromide. The two-dimensional sheet structure of graphdiyne provides a high specific surface area and a large number of active sites, which helps photogenerated electrons to participate in the catalytic reaction and further improves the photocatalytic efficiency.
[0011] Preferably, for every 1 g of graphdiyne, 0.4 mol to 0.83 mol of bismuth source is added.
[0012] Preferably, the molar ratio of the bismuth source to the bromine source is 1:0.9 to 1.1.
[0013] The temperature of the hydrothermal reaction plays a key role in the formation and growth of the nanosheets; preferably, the temperature of the hydrothermal reaction is 110°C to 150°C. Preferably, the time of the hydrothermal reaction is 12 h to 16 h.
[0014] Preferably, the bismuth source is bismuth nitrate pentahydrate or bismuth nitrate.
[0015] Preferably, the bromine source is sodium bromide or potassium bromide.
[0016] Through the design of the heterojunction structure, the present invention effectively realizes the separation and transfer of photo-generated charges, broadens the light absorption range of the photocatalyst, and significantly improves the photocatalytic efficiency. At the same time, the introduction of graphdiyne enhances the stability and reactivity of the material, achieving the purpose of improving the photocatalytic performance.
[0017] Compared with the prior art, the present invention has the following beneficial effects:
[0018] In the present invention, the bismuth source and graphdiyne are dissolved in water, and then the bromine source is added, and a graphdiyne / bismuth oxybromide heterojunction photocatalyst is synthesized in one pot by a hydrothermal method; avoiding the problem that in the prior art, two substances are synthesized separately and then compounded, resulting in poor interfacial compatibility between the two substances. Moreover, the preparation process of the present invention is simple, easy to operate, the raw materials are cheap and easy to obtain, and it is suitable for large-scale production.
[0019] Through hydrothermal reaction, the present invention forms bismuth oxybromide nanosheets on the surface of graphdiyne, constructing a graphdiyne / bismuth oxybromide heterojunction photocatalyst formed by the compound of bismuth oxybromide nanosheets and graphdiyne. Through the compound of bismuth oxybromide and graphdiyne, on the one hand, the heterojunction structure formed by bismuth oxybromide and graphdiyne enables photo-generated electrons to transfer from bismuth oxybromide to graphdiyne, while photo-generated holes remain in bismuth oxybromide, separating electrons and holes in different materials and reducing the recombination probability of electron-hole pairs; and the effective separation and transfer of electrons enable more photo-generated charges to participate in the photocatalytic reaction, improving the reaction efficiency. On the other hand, after compounding, the graphdiyne / bismuth oxybromide photocatalyst effectively expands the light absorption range, and the expanded light absorption range enables the photocatalyst to utilize more solar energy and improve the photocatalytic efficiency.
[0020] The present invention utilizes the excellent electrical conductivity of graphdiyne to enable the rapid transfer of photo-generated electrons and prevent recombination. At the same time, the high specific surface area and rich reactive sites of graphdiyne enhance the reaction rate on the surface of the photocatalyst and further improve the catalytic activity. In addition, the introduction of graphdiyne in the present invention not only improves the photocatalytic efficiency but also enhances the stability of the material, with a small decay in photocatalytic activity during recycling; the stable heterojunction structure formed during the hydrothermal synthesis makes its structure stable during long-term use and not easily degraded. The CO 2 conversion rate of the graphdiyne / bismuth oxybromide heterojunction photocatalyst prepared by the present invention is 5.1 times that of pure bismuth oxybromide; and after 5 cycles, the CO yield still does not show obvious attenuation, and the graphdiyne / bismuth oxybromide heterojunction photocatalyst has good stability. Description of the Drawings
[0021] Figure 1 XRD patterns of BiOBr prepared in Comparative Example 1 of the present invention and GDY / BiOBr prepared in Examples 1 to 3.
[0022] Figure 2 XRD pattern of graphdiyne of the present invention.
[0023] Figure 3 SEM images of BiOBr prepared in Comparative Example 1 of the present invention and GDY / BiOBr prepared in Example 2; wherein, (a) is BiOBr and (b) is GDY / BiOBr.
[0024] Figure 4 CO reduction performance diagrams of graphdiyne, BiOBr prepared in Comparative Example 1 and GDY / BiOBr prepared in Examples 1 to 3 of the present invention 2 diagrams.
[0025] Figure 5 CO reduction performance diagrams of GDY / BiOBr prepared in Example 2 of the present invention under different conditions 2 diagrams.
[0026] Figure 6 Photocatalytic stability test diagram of GDY / BiOBr prepared in Example 2 of the present invention. Detailed implementation manners
[0027] In order to enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below with reference to specific examples and drawings.
[0028] In the description of the present invention, unless otherwise specified, the reagents used are commercially available and the methods used are conventional techniques in the art.
[0029] Example 1
[0030] This example provides a method for preparing a graphdiyne / bismuth oxybromide heterojunction photocatalyst.
[0031] 1.1) Add 1.4552 g of Bi(NO 3 ) 3 ·5H 2 O and 0.0073 g of graphdiyne to 30 mL of deionized water, stir for 1 h to obtain a suspension.
[0032] 1.2) Dissolve 0.3087 g of NaBr in 30 mL of deionized water to obtain a NaBr solution.
[0033] 1.3) Slowly add the NaBr solution to the suspension and stir for 1 h to obtain a precursor solution.
[0034] 1.4) Pour the precursor solution into a 100 mL polytetrafluoroethylene autoclave, hydrothermally react at 120 °C for 12 h. After cooling to room temperature, wash with deionized water and alcohol, and then dry in an oven at 60 °C for 10 h to obtain a graphdiyne / bismuth oxybromide heterojunction photocatalyst, denoted as GDY / BiOBr.
[0035] Example 2
[0036] This example provides a method for preparing a graphdiyne / bismuth oxybromide heterojunction photocatalyst.
[0037] 1.1) Add 1.4552 g of Bi(NO 3 ) 3 ·5H 2 O and 0.0049 g of graphdiyne to 30 mL of deionized water, stir for 1 h to obtain a suspension.
[0038] 1.2) Dissolve 0.3087 g of NaBr in 30 mL of deionized water to obtain a NaBr solution.
[0039] 1.3) Slowly add the NaBr solution dropwise to the suspension and stir for 1 h to obtain a precursor solution.
[0040] 1.4) Pour the precursor solution into a 100 mL polytetrafluoroethylene autoclave, hydrothermally react at 120 °C for 12 h. After cooling to room temperature, wash with deionized water and alcohol, and then dry in an oven at 60 °C for 10 h to obtain a graphdiyne / bismuth oxybromide heterojunction photocatalyst, denoted as GDY / BiOBr.
[0041] Example 3
[0042] This example provides a method for preparing a graphdiyne / bismuth oxybromide heterojunction photocatalyst.
[0043] 1.1) Add 1.4552 g of Bi(NO 3 ) 3 ·5H 2 O and 0.0036 g of graphdiyne to 30 mL of deionized water, stir for 1 h to obtain a suspension.
[0044] 1.2) Dissolve 0.3087 g of NaBr in 30 mL of deionized water to obtain a NaBr solution.
[0045] 1.3) Slowly add the NaBr solution dropwise to the suspension and stir for 1 h to obtain a precursor solution.
[0046] 1.4) Pour the precursor solution into a 100 mL polytetrafluoroethylene autoclave, hydrothermally treat it at 120 °C for 12 h. After cooling to room temperature, wash it with deionized water and alcohol, and then dry it in a drying oven at 60 °C for 10 h to obtain a graphdiyne / bismuth oxybromide heterojunction photocatalyst, denoted as GDY / BiOBr.
[0047] Example 4
[0048] This example provides a method for preparing a graphdiyne / bismuth oxybromide heterojunction photocatalyst.
[0049] 1.1) Add 1.4552 g of Bi(NO 3 ) 3 ·5H 2 O and 0.0073 g of graphdiyne to 30 mL of deionized water, stir for 1 h to obtain a suspension.
[0050] 1.2) Dissolve 0.3087 g of NaBr in 30 mL of deionized water to obtain a NaBr solution.
[0051] 1.3) Slowly add the NaBr solution dropwise to the suspension and stir for 1 h to obtain a precursor solution.
[0052] 1.4) Pour the precursor solution into a 100 mL polytetrafluoroethylene autoclave, hydrothermally treat it at 110 °C for 16 h. After cooling to room temperature, wash it with deionized water and alcohol, and then dry it in a drying oven at 60 °C for 10 h to obtain a graphdiyne / bismuth oxybromide heterojunction photocatalyst, denoted as GDY / BiOBr.
[0053] Example 5
[0054] This example provides a method for preparing a graphdiyne / bismuth oxybromide heterojunction photocatalyst.
[0055] 1.1) Add 1.4552 g of Bi(NO 3 ) 3 ·5H 2 O and 0.0073 g of graphdiyne to 30 mL of deionized water, stir for 1 h to obtain a suspension.
[0056] 1.2) Dissolve 0.3087 g of NaBr in 30 mL of deionized water to obtain a NaBr solution.
[0057] 1.3) Slowly add the NaBr solution dropwise to the suspension and stir for 1 h to obtain a precursor solution.
[0058] 1.4) The precursor solution was poured into a 100 mL polytetrafluoroethylene autoclave, hydrothermally heated at 150° C. for 14 h, cooled to room temperature, washed with deionized water and alcohol, and then dried in a drying oven at 60° C. for 10 h to obtain a Graphene dithiocarbide / bismuth oxybromide heterojunction photocatalyst, denoted as GDY / BiOBr.
[0059] Comparative Example 1
[0060] This comparative example provides a method for preparing bismuth oxybromide.
[0061] 1.1) 1.4552 g of Bi(NO 3 ) 3 ·5H 2 O was added into 30 mL of deionized water and stirred for 1 h to obtain a suspension.
[0062] 1.2) Dissolve 0.3087 g of NaBr in 30 mL of deionized water to obtain a NaBr solution.
[0063] 1.3) Slowly add NaBr solution dropwise to the suspension and stir for 1 h to obtain a precursor solution.
[0064] 1.4) The precursor solution was poured into a 100 mL polytetrafluoroethylene autoclave, hydrothermaled at 120° C. for 12 h, cooled to room temperature, washed with deionized water and alcohol, and then dried in a drying oven at 60° C. for 10 h to obtain bismuth oxybromide, i.e., BiOBr.
[0065] Examples 1 to 5 of the present invention all prepare Graphene / bismuth oxybromide heterojunction photocatalysts. The following is a study using the Graphene / bismuth oxybromide heterojunction photocatalysts prepared in Examples 1 to 3 and Comparative Example 1 as examples. The specific research methods and results are as follows:
[0066] Figure 1 The XRD patterns of BiOBr prepared in Comparative Example 1 and GDY / BiOBr prepared in Examples 1 to 3 are shown in FIG. Figure 1 It can be seen that the main diffraction peaks of the sample are consistent with the standard card JCPDS 09-0393. The diffraction peaks with diffraction angles of 10.9°, 22.0°, 25.3°, 31.8°, 32.5°, 39.5°, 46.3°, 50.7°, 56.3° and 57.3° correspond to the (001), (002), (101), (102), (110), (112), (200), (104), (114) and (212) crystal planes, respectively. The main diffraction peaks are the (102) and (110) crystal planes.
[0067] Figure 2XRD pattern of graphdiyne. Compared with the XRD patterns of GDY / BiOBr prepared in Examples 1 to 3, the peak at 23.0° may be related to the (002) crystal plane of the carbon material. It indicates that the GDY / BiOBr photocatalyst containing graphdiyne is prepared in the present invention.
[0068] Figure 3 SEM images of BiOBr prepared in Comparative Example 1 and GDY / BiOBr prepared in Example 2; among them, (a) is BiOBr and (b) is GDY / BiOBr. As can be seen from Figure 3 it, BiOBr is a smooth flake structure, and the surface of the GDY / BiOB photocatalyst becomes rough compared with BiOBr.
[0069] Photocatalytic test:
[0070] Under the irradiation of a 300 W xenon lamp, the photocatalytic CO 2 reduction performance of GDY / BiOBr and graphdiyne prepared in Examples 1 to 3 and BiOBr prepared in Comparative Example 1 was tested, and the results are as Figure 4 shown; the specific implementation method is as follows: Put 10 mg of the sample and a small amount of distilled water into a weighing bottle, ultrasonicate for 20 min, and dry in an oven at 60 °C for 10 h; then place it in a reactor and evacuate for 15 min; and introduce high-purity carbon dioxide gas and 10 μL of deionized water into the reactor; irradiate the reactor under a 200 mW·cm -2 xenon lamp for 3 h; the product is determined on a Huifen GC-7800 gas chromatograph.
[0071] Figure 4 CO 2 reduction performance graphs of graphdiyne, BiOBr prepared in Comparative Example 1, and GDY / BiOBr prepared in Examples 1 to 3. As can be seen from Figure 4 it, the CO 2 reduction performances of GDY / BiOBr prepared in Examples 1 to 3 are 178.7 μmol·g -1 h -1 , 260.6 μmol·g -1 h -1 and 142.5 μmol·g -1 ·h -1 respectively; compared with the CO 2 reduction performance of single graphdiyne and BiOBr, the GDY / BiOBr prepared in the present invention significantly improves the photocatalytic CO 2 reduction efficiency; among them, when 0.62 mol of bismuth source is added per 1 g of graphdiyne, the CO 2 conversion rate of GDY / BiOBr is 5.1 times that of pure bismuth oxybromide, showing the best CO2 Restore performance,
[0072] Figure 5 CO of GDY / BiOBr prepared in Example 2 under different conditions 2 Restore performance graph. Figure 5 As shown, no catalyst was added, no light was applied, or CO 2 The atmosphere changes to N 2 In the case of atmosphere, almost no CO is detected, indicating that CO comes from CO 2 , indicating that CO in the reaction system 2 , photocatalyst and light are all necessary conditions for photocatalytic reaction.
[0073] Figure 6 This is a test diagram of the photocatalytic stability of GDY / BiOBr prepared in Example 2. The cycle experiment shows that after 5 cycles, the CO yield still has no obvious attenuation, proving that the GDY / BiOBr prepared in Example 2 has good stability; it shows that the Graphene / Bismuth oxybromide heterojunction photocatalyst prepared in the present invention has a stable structure during long-term use and is not easy to degrade.
[0074] It should be noted that when the present invention involves a numerical range, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes a preferred embodiment. Although the preferred embodiments of the present invention have been described, once those skilled in the art know the basic creative concept, they can make other changes and modifications to these embodiments, and these changes and modifications all fall within the scope of the present invention.
[0075] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. If these modifications and variations of the present invention fall within the scope of the equivalent technology of the present invention, the present invention is also intended to include these modifications and variations.
Claims
1. A method for preparing a Graphene Oxybromide / BiOBr heterojunction photocatalyst, characterized in that: The following steps are involved: A bismuth source and graphyne are dissolved in water, and a bromine source is added, and a hydrothermal method is used to make bismuth ions provided by the bismuth source react with bromide ions provided by the bromine source, and bismuth oxybromide nanosheets are loaded on the surface of graphyne to obtain a graphyne / bismuth oxybromide heterojunction photocatalyst formed by a composite of graphyne and bismuth oxybromide nanosheets.
2. The method for preparing the Graphene Oxybromide / BiOBr heterojunction photocatalyst according to claim 1, characterized in that: For every 1g of graphyne, 0.4mol to 0.83mol of bismuth source is added.
3. The method for preparing the Graphene Oxybromide / BiOBr heterojunction photocatalyst according to claim 1, characterized in that: The molar ratio of the bismuth source to the bromine source is 1:0.9-1.
1.
4. The method for preparing the Graphene Oxybromide / BiOBr heterojunction photocatalyst according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 110° C. to 150° C., and the time of the hydrothermal reaction is 12 h to 16 h.
5. The method for preparing the Graphene Oxybromide / BiOBr heterojunction photocatalyst according to claim 1, characterized in that: The bismuth source is bismuth nitrate pentahydrate or bismuth nitrate.
6. The method for preparing the Graphene Oxybromide / BiOBr heterojunction photocatalyst according to claim 1, characterized in that: The bromine source is sodium bromide or potassium bromide.
7. A graphyne / bismuth oxybromide heterojunction photocatalyst prepared by the preparation method according to any one of claims 1 to 6.
8. Use of the graphyne / bismuth oxybromide heterojunction photocatalyst according to claim 7 in the field of photocatalytic reduction of carbon dioxide.