Metal-organic framework ternary composite photocatalytic material constructed based on flower-shaped structure as well as preparation method and application of metal-organic framework ternary composite photocatalytic material

Abstract

The invention discloses a metal organic framework ternary composite photocatalytic material constructed on the basis of a flower-shaped structure as well as a preparation method and application of the metal organic framework ternary composite photocatalytic material, and belongs to the technical field of Zr-based metal organic framework catalysts. According to the invention, MOF with photocatalytic activity is combined with two heterojunctions. The ternary heterojunction composite photocatalytic material BOI-UN / AgI is synthesized, the photoresponse performance of the ternary heterojunction composite photocatalytic material BOI-UN / AgI is remarkably improved, and the photocatalytic activity is effectively improved; the ternary heterojunction composite photocatalytic material BOI-UN / AgI disclosed by the invention shows a good degradation effect on tetracycline, and after the ternary heterojunction composite photocatalytic material BOI-UN / AgI is recycled for five times, the photocatalytic efficiency of the ternary heterojunction composite photocatalytic material BOI-UN / AgI still keeps excellent performance; the catalytic material BOI-UN / AgI disclosed by the invention has relatively strong light response capability, narrower band gap and higher electron transfer efficiency, and effectively inhibits electron-hole recombination, so that the catalytic performance of the composite material is remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of Zr-based metal organic framework catalysts, and specifically relates to a metal organic framework ternary composite photocatalytic material constructed based on a flower-like structure, and a preparation method and application thereof. Background Art

[0002] The core of semiconductor photocatalytic technology is to develop photocatalysts with simple processes, high efficiency, and stability. Given the excellent properties of MOFs materials, such as multiple active sites, high specific surface area, semiconductor-like behavior, and easy functionalization, they have certain application potential in the field of photocatalytic degradation of pollutants. Most original MOFs materials have poor photocatalytic performance and cannot effectively degrade harmful substances in wastewater treatment. It is well known that the wavelength range of sunlight is 250-2500nm, of which visible light accounts for 43% of all solar radiation, while ultraviolet light accounts for only 5%. Due to the wide band gap, most photocatalysts can only absorb ultraviolet light, resulting in low sunlight utilization efficiency. In addition, the recombination of photogenerated electrons and holes easily occurs inside or on the surface of the photocatalyst, which also severely limits its catalytic activity. Therefore, the research on visible light-responsive photocatalysts with high activity and stability is particularly important. Summary of the Invention

[0003] The present invention aims to overcome the shortcomings of existing technologies by providing a metal-organic framework ternary composite photocatalytic material based on a flower-like structure, as well as its preparation method and application. By combining a photocatalytically active MOF with two heterojunctions, the present invention achieves efficient photocatalytic performance and high catalyst stability, making it suitable for environmental applications such as water treatment and waste gas purification.

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows: The present invention provides a method for preparing a metal-organic framework ternary composite photocatalytic material based on a flower-like structure, comprising the following steps: Step 1: Add a certain amount of Bi(NO3)3·5H2O powder into ethylene glycol and disperse it evenly to obtain solution I. Add KI powder into ethylene glycol and disperse it evenly to obtain solution II. Step 2: Mix solution I and solution II and stir them evenly, add a certain amount of UiO-66-NH2, transfer the mixture to a hydrothermal reactor for reaction, and perform post-treatment after the reaction to obtain the product BOI / UN; Step 3: Disperse the product BOI / UN obtained in step 2 in deionized water and stir evenly to obtain solution A; disperse silver nitrate powder in deionized water and stir evenly to obtain solution B; add solution B to solution A, stir and react under certain conditions; after the reaction is completed, let it stand and perform post-treatment to obtain the ternary composite photocatalytic material.

[0005] Furthermore, the molar ratio of the Bi(NO3)3·5H2O powder to the KI powder in step 1 is 1:1.

[0006] Furthermore, the reaction time in step 2 is 10-20 hours, and the reaction temperature is 100-200°C.

[0007] Furthermore, the mass of UiO-66-NH2 added in step 2 is 5% to 100% of the mass of Bi(NO3)3·5H2O powder.

[0008] Furthermore, the mass ratio of the silver nitrate powder to BOI / UN in step 3 is 1:1 to 8:1.

[0009] Furthermore, the stirring reaction under certain conditions in step 3 specifically includes: vigorously stirring for 2 to 4 hours in a light-proof condition.

[0010] Furthermore, the post-treatment described in step three is specifically as follows: pouring out the upper liquid layer, washing the lower solid layer with deionized water and anhydrous ethanol alternately for several times, and drying the washed product in a constant temperature forced air drying oven at 80° C. for 12 hours.

[0011] The present invention also provides a metal-organic framework ternary composite photocatalytic material based on a flower-like structure, which is prepared by the method for preparing the metal-organic framework ternary composite photocatalytic material based on a flower-like structure.

[0012] The present invention also provides an application of the metal organic framework ternary composite photocatalytic material constructed based on the flower-like structure in photocatalytic degradation of TC.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The present invention successfully synthesized the ternary heterojunction composite photocatalytic material BOI-UN / AgI, which significantly improved the light response performance and photocatalytic activity. The ternary heterojunction composite photocatalytic material BOI-UN / AgI of the present invention exhibits a good degradation effect on tetracycline (TC), and its photocatalytic efficiency still maintains excellent performance after five cycles of use; The catalytic material BOI-UN / AgI of the present invention has a strong light response ability, a narrower band gap, and a faster electron transfer efficiency, which effectively inhibits the recombination of electrons and holes, and significantly improves the catalytic performance of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1The XRD spectra of the metal organic framework (MOFs) catalysts BiOI, BOI / UN, and BOI-UN1 / AgI4 are shown in Figure 1. As can be seen from the figure, the composite material BOI-UN1 / AgI4 has four distinct characteristic diffraction peaks at 2θ of 22.319°, 23.707°, 39.205°, and 46.309°, corresponding to the four crystal planes (100), (002), (110), and (112) in the tetragonal AgI standard card. However, compared with the AgI standard card, the composite material BOI-UN1 / AgI4 does not have a characteristic diffraction peak at 2θ of 25.354° corresponding to the (101) crystal plane, which may be due to the coupling of the three materials, resulting in the masking of the characteristic peak. In addition, the composite material BOI-UN1 / AgI4 has two characteristic diffraction peaks at 2θ of 29.6° and 31.6°, which correspond to the two crystal planes (102) and (110) in the tetragonal BiOI standard card. This shows that not only AgI but also BiOI exists in the composite material BOI-UN1 / AgI4, proving that the three materials are successfully coupled together.

[0015] Figure 2a is the SEM image of BOI / UN of the present invention; Figure 2b is the SEM image of BOI-UN1 / AgI4 of the present invention; Figure 2a and 2b As can be seen, the main structure of BOI-UN1 / AgI4 is similar to that of BOI / UN, also composed of a large number of nanosheets orderly aggregated to form uniform three-dimensional nanospheres, presenting a hollow flower-like structure with a diameter of approximately 3 μm. UiO-66-NH2 nanoparticles can be observed distributed on the BiOI surface, while many tiny AgI nanoparticles are anchored on the surface of BOI / UN, resulting in a slightly rough overall appearance.

[0016] Figure 3a This is the SEM-mapping image of BOI-UN1 / AgI4 of the present invention; Figure 3b is the element distribution diagram of BOI-UN1 / AgI4 of the present invention; Figure 3a and 3b It can be seen that the elements in BOI-UN1 / AgI4 are evenly distributed, containing seven elements: C, O, N, Zr, Bi, I, and Ag. It can also be seen that Zr, Bi, and Ag are evenly distributed on the sphere.

[0017] Figure 4a N2 adsorption-desorption curve of the BET image of BOI-UN1 / AgI4 of the present invention; Figure 4b is the pore size distribution diagram of the BOI-UN1 / AgI4 BET image of the present invention; Figure 4a It can be observed that the N2 adsorption-desorption curve of BOI-UN1 / AgI4 in the relative pressure range of 0.6~1.0 is a typical IV type isotherm with an H3 type hysteresis loop, indicating that a mesoporous structure exists in the material. The specific surface area of ​​BOI / UN is calculated to be 25.32 m 2 / g. Figure 4b This is the pore size distribution diagram of the material. It can be seen from the figure that the average pore size of BOI-UN1 / AgI4 is 10.8nm, proving the existence of mesoporous structure in the material.

[0018] Figure 5a This is the full XPS spectrum of BOI-UN1 / AgI4 of the present invention. It can be seen from the figure that BOI-UN1 / AgI4 contains seven elements: C, O, N, Zr, Bi, I, and Ag, which is consistent with the SEM-mapping results.

[0019] Figure 5b This is the C 1s high-resolution spectrum of BOI-UN1 / AgI4 of the present invention. As can be seen from the figure, the three characteristic peaks at binding energies of 284.80 eV, 286.05 eV and 288.32 eV correspond to the C—C bond, C—O bond and C=O bond in the composite material BOI-UN1 / AgI4, respectively.

[0020] Figure 5c This is the high-resolution O 1s spectrum of BOI-UN1 / AgI4 of the present invention. As can be seen from the figure, the three characteristic peaks at binding energies of 529.56 eV, 530.59 eV, and 531.79 eV are related to Zr-O bonds / Bi-O bonds, C=O bonds, and surface hydroxyl groups C-OH. Because both Zr-O and Bi-O bonds exist at 529.52 eV, the characteristic peak intensity there is higher.

[0021] Figure 5d The high-resolution spectrum of Zr 3d of BOI-UN1 / AgI4 of the present invention is shown in the figure. It can be seen that the two characteristic peaks at the binding energy of 181.87 eV and 184.41 eV are respectively related to the Zr 3d 5 / 2 Orbital and Zr 3d 3 / 2 Orbital correlation confirms that Zr in the composite material BOI-UN1 / AgI4 4+ existence.

[0022] Figure 5e The high-resolution spectrum of Bi 4f of BOI-UN1 / AgI4 of the present invention is shown in the figure. It can be seen that the two characteristic peaks at the binding energy of 158.81 eV and 164.14 eV are respectively related to the Bi 4f 5 / 2 Orbital and Bi 4f 3 / 2 Orbital correlation confirms Bi3+ existence.

[0023] Figure 5f The I 3d high-resolution spectrum of BOI-UN1 / AgI4 of the present invention is shown in the figure. It can be seen that the two characteristic peaks at the binding energy of 619.84 eV and 631.33 eV are respectively 5 / 2 Tracks and I 3d 3 / 2 Orbital correlation, confirmed I -1 existence.

[0024] Figure 5g The high-resolution spectrum of Ag 3d of BOI-UN1 / AgI4 of the present invention is shown in the figure. It can be seen that the two characteristic peaks at the binding energy of 368.48 eV and 374.50 eV are respectively related to the Ag 3d 5 / 2 Orbitals and Ag 3d 3 / 2 Orbital correlation confirms Ag +1 The XPS results show that there is Zr in the composite material. 4+ and Bi 3+ , there is also Ag +1 . This further confirmed the successful synthesis of the composite material BOI-UN1 / AgI4.

[0025] Figure 6a Graph showing the experimental results of catalytic degradation of TC by the ternary composite material BOI-UN / AgI obtained in Examples 2 to 6 of the present invention; Figure 6b This is the first-order kinetic fitting of the catalytic degradation of TC by the ternary composite material BOI-UN / AgI obtained in Examples 2 to 6 of the present invention.

[0026] Figure 7 This is a cycle test diagram of the ternary composite material BOI-UN1 / AgI4 of the present invention.

[0027] Figure 8a The photoluminescence spectra of UiO-66, the composite material BOI / UN and the ternary composite material BOI-UN1 / AgI4 of the present invention are shown; Figure 8b Electrochemical impedance spectroscopy (EIS) of the present invention's UiO-66, BOI / UN composite material, and ternary composite material BOI-UN1 / AgI4. Figure 8c The photocurrent response diagrams of UiO-66, the composite material BOI / UN and the ternary composite material BOI-UN1 / AgI4 of the present invention are shown; Figure 9a is the absorbance of the ultraviolet-visible diffuse reflectance spectrum (UV-DRS) of AgI and BOI-UN1 / AgI4 of the present invention; Figure 9bis the bandgap width of the ultraviolet-visible diffuse reflectance spectrum (UV-DRS) of AgI and BOI-UN1 / AgI4 of the present invention. DETAILED DESCRIPTION

[0028] The present invention is described in further detail below with reference to the embodiments.

[0029] Those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature within the art or in accordance with the product instructions are used. Where the manufacturers of the reagents or instruments used are not specified, they are conventional products that can be purchased. In the present invention, UiO-66-NH2, BiOI, and the binary composite material BOI / UN are all existing known materials.

[0030] Example 1

[0031] 0.970g of Bi(NO3)3·5H2O powder was weighed and dispersed in 25mL of ethylene glycol. The mixture was dispersed under ultrasonic conditions for 30 minutes, followed by magnetic stirring for 20 minutes to obtain a homogeneous solution I. Next, 0.416g of KI powder was weighed and dispersed in 25mL of ethylene glycol. Ultrasonic dispersion was performed for 30 minutes to obtain a homogeneous solution II. Solutions I and II were mixed and stirred for 1 hour to thoroughly mix. 88.00mg of UiO-66-NH2 was then added. The mixture was transferred to a 100mL hydrothermal reactor and reacted at 150°C for 12 hours. After completion of the reaction, the solid product was centrifuged and washed three times with deionized water and anhydrous ethanol to remove residual impurities. Finally, the product was dried in a constant temperature forced air drying oven at 80°C for 12 hours to obtain the product, which was labeled as BOI / UN.

[0032] Example 2

[0033] 0.2 g of the BOI / UN product prepared in Example 1 was uniformly dispersed in 20 mL of deionized water, ultrasonically treated for 30 minutes, and magnetically stirred for 20 minutes to prepare Solution A. 0.0085 g of silver nitrate (AgNO3) powder was dispersed in 20 mL of deionized water, ultrasonically treated for 30 minutes, and magnetically stirred for 20 minutes to obtain Solution B. Subsequently, Solution B was slowly added to Solution A and vigorously stirred in the dark for 4 hours. After the reaction was complete, the mixture was allowed to stand at room temperature for 40 minutes to allow for solid-liquid separation. The supernatant was then decanted and the product was washed three times with alternating deionized water and anhydrous ethanol to remove impurities. Finally, the washed product was dried in a constant-temperature forced-air drying oven at 80°C for 12 hours to obtain the ternary composite material BOI-UN / AgI, labeled BOI / UN8 / AgI1.

[0034] Example 3

[0035] 0.2 g of the BOI / UN product prepared in Example 1 was uniformly dispersed in 20 mL of deionized water, ultrasonically treated for 30 minutes, and magnetically stirred for 20 minutes to prepare Solution A. 0.017 g of silver nitrate (AgNO3) powder was dispersed in 20 mL of deionized water, ultrasonically treated for 30 minutes, and magnetically stirred for 20 minutes to obtain Solution B. Subsequently, Solution B was slowly added to Solution A and vigorously stirred in the dark for 4 hours. After the reaction was complete, the mixture was allowed to stand at room temperature for 40 minutes to allow for solid-liquid separation. The supernatant was then decanted and washed three times with alternating deionized water and anhydrous ethanol to remove impurities. Finally, the washed product was dried in a constant-temperature forced-air drying oven at 80°C for 12 hours to obtain the ternary composite material BOI-UN / AgI, labeled BOI / UN4 / AgI1.

[0036] Example 4

[0037] 0.2 g of the BOI / UN product prepared in Example 1 was uniformly dispersed in 20 mL of deionized water, ultrasonically treated for 30 minutes, and magnetically stirred for 20 minutes to prepare Solution A. 0.034 g of silver nitrate (AgNO3) powder was dispersed in 20 mL of deionized water, ultrasonically treated for 30 minutes, and magnetically stirred for 20 minutes to obtain Solution B. Subsequently, Solution B was slowly added to Solution A and vigorously stirred in the dark for 4 hours. After the reaction was complete, the mixture was allowed to stand at room temperature for 40 minutes to allow for solid-liquid separation. The supernatant was then decanted and washed three times with alternating deionized water and anhydrous ethanol to remove impurities. Finally, the washed product was dried in a constant-temperature forced-air drying oven at 80°C for 12 hours to obtain the ternary composite material BOI-UN / AgI, labeled BOI / UN1 / AgI1.

[0038] Example 5

[0039] 0.2 g of the product BOI / UN prepared in Example 1 was uniformly dispersed in 20 mL of deionized water, ultrasonically treated for 30 minutes, and magnetically stirred for 20 minutes to prepare Solution A. 0.068 g of silver nitrate (AgNO3) powder was dispersed in 20 mL of deionized water, ultrasonically treated for 30 minutes, and magnetically stirred for 20 minutes to obtain Solution B. Subsequently, Solution B was slowly added to Solution A and vigorously stirred in the dark for 4 hours. After the reaction was complete, the mixture was allowed to stand at room temperature for 40 minutes to allow for solid-liquid separation. The supernatant was then decanted and washed three times with alternating deionized water and anhydrous ethanol to remove impurities. Finally, the washed product was dried in a constant-temperature forced-air drying oven at 80°C for 12 hours to obtain the ternary composite material BOI-UN / AgI, labeled BOI / UN1 / AgI2.

[0040] Example 6

[0041] 0.2 g of the BOI / UN product prepared in Example 1 was uniformly dispersed in 20 mL of deionized water, ultrasonically treated for 30 minutes, and magnetically stirred for 20 minutes to prepare Solution A. 0.136 g of silver nitrate (AgNO3) powder was dispersed in 20 mL of deionized water, ultrasonically treated for 30 minutes, and magnetically stirred for 20 minutes to obtain Solution B. Subsequently, Solution B was slowly added to Solution A and vigorously stirred in the dark for 4 hours. After the reaction was complete, the mixture was allowed to stand at room temperature for 40 minutes to allow for solid-liquid separation. The supernatant was then decanted and washed three times with alternating deionized water and anhydrous ethanol to remove impurities. Finally, the washed product was dried in a constant-temperature forced-air drying oven at 80°C for 12 hours to obtain the ternary composite material BOI-UN / AgI, labeled BOI / UN1 / AgI4.

[0042] The BOI-UN / AgI materials prepared in Examples 2-6 were used to perform photocatalytic degradation of TC. The experimental system employed a Porphyrin PCX-50C Discover multi-channel photocatalytic reaction system as the sole light source. The photocatalytic reaction vessel was constructed entirely of quartz, and stirring was performed throughout the reaction to ensure uniform dispersion of the catalyst in the water. Before the photocatalytic experiments began, a dark reaction adsorption experiment was performed to eliminate any interference from adsorption effects. The specific experimental steps for photocatalytic degradation of TC are as follows: (1) Add 10 mg / L TC solution into a 50 mL photocatalytic reaction bottle; (2) Add 10 mg of catalyst to the reaction bottle; (3) Conduct a half-hour dark reaction experiment in darkness; (4) Turn on the xenon lamp to conduct the photocatalytic reaction. Take 5 mL of sample every 30 minutes, and the sampling time is 30 minutes apart. (5) Filter the solution through a 0.22 μm filter membrane and add it to a cuvette. Measure the absorbance of the solution using a UV spectrophotometer. (6) All experiments were performed three times and the average value was taken; (7) The TC removal efficiency is obtained by the following formula:

[0043] Where R is the removal efficiency, %; C0 is the initial concentration of TC, mg / L; C is the measured concentration of TC at time t, mg / L.

[0044] The experimental results are shown in Figure 6. As can be seen from the figure, during the dark reaction phase, BOI-UN1 / AgI1, BOI-UN1 / AgI2, and BOI-UN1 / AgI4 achieved the best adsorption effects, with adsorption removal rates reaching approximately 40%. However, the adsorption rates of BOI-UN4 / AgI1 and BOI-UN8 / AgI1 showed a certain downward trend. Under the same conditions, compared with BOI / UN, the adsorption rates of BOI-UN1 / AgI1, BOI-UN1 / AgI2, and BOI-UN1 / AgI4 increased within 30 minutes. This may be due to the addition of AgI increasing the adsorption sites and thus the adsorption rate, indicating the successful synthesis of the composite material.

[0045] After the dark reaction, photocatalytic experiments under illumination revealed a significant decrease in TC concentration, demonstrating that all catalysts effectively photocatalytically degrade pollutants under visible light. As shown in Figure 6, the catalytic activities of BOI-UN1 / AgI1, BOI-UN1 / AgI2, and BOI-UN1 / AgI4 are significantly higher than those of BOI / UN, indicating that the introduction of the semiconductor AgI enhances the photocatalytic performance of the overall material. Furthermore, the photocatalytic performance of the catalysts differed depending on the BiOI and AgI content. This is likely due to the fact that too little AgI leads to insufficient heterojunction formation, while excessive BiOI leads to BiOI particle agglomeration, hindering the transport of photogenerated charge carriers between AgI and BiOI species. Therefore, the appropriate BiOI and AgI content plays a crucial role in the photocatalytic performance of the composite catalysts. Combined with the results of the dark adsorption experiments, the composite BOI-UN1 / AgI4 exhibits the best photocatalytic performance and the highest photocatalytic degradation efficiency among these materials. After 15 minutes of visible light irradiation, the degradation efficiency of TC by BOI-UN1 / AgI4 reached 84%. After 60 minutes of irradiation, the removal efficiency of TC reached 96%, indicating that TC was almost completely degraded. Using first-order kinetic fitting, it was found that within 45 minutes, the reaction rate constants k for BOI-UN1 / AgI1, BOI-UN1 / AgI2, BOI-UN1 / AgI4, BOI-UN4 / AgI1, BOI-UN8 / AgI1, UiO-66, and BOI / UN were 0.0439, 0.04625, 0.0479, 0.04148, 0.04165, 0.01369, and 0.02174 min, respectively. -1 It can be clearly seen that BOI-UN1 / AgI4 has the fastest degradation rate.

[0046] The catalyst recycling performance test was conducted on the ternary composite material BOI-UN / Ag prepared in Example 6. After the catalytic reaction was completed, the catalyst was recovered and washed with water and ethanol multiple times, and then placed in an oven to dry overnight to complete the catalyst recycling. The photocatalytic experiment of TC was repeated and the removal rate was measured to study the catalyst recycling performance. The experimental results are shown in Figure 2. Figure 7 As shown by Figure 7 As can be seen, after five cycles of use, the TC removal efficiency of BOI-UN1 / AgI4 in the visible light catalytic system was still able to maintain around 90%, which strongly demonstrates the good stability and reusability of BOI-UN1 / AgI4. The decline in TC removal efficiency may be due to the occupation of some active sites on the catalyst, which affects the degradation effect. Therefore, the ternary composite material BOI-UN1 / AgI4 of the present invention exhibits stable performance in the visible light catalytic system and can continuously maintain high TC removal efficiency, demonstrating the excellent reusability of the catalyst.

[0047] The photoelectrochemical performance of the ternary composite material BOI-UN / AgI prepared in Example 6 was analyzed. Photoluminescence (PL) was measured using an Edinburgh FLs-980 steady-state transient fluorescence spectrometer. Photocurrent (PC) and electrochemical impedance spectroscopy (EIS) were measured using a three-electrode electrochemical analysis method on a CHI 760E electrochemical workstation to complete the photoelectric performance testing experiments.

[0048] The results are as follows Figures 8a to 8c As shown by Figure 8a It can be seen that the PL intensity of the ternary composite material BOI-UN1 / AgI4 is the weakest. The weak PL intensity indicates that the - -h+ has a better inhibition on the composite. This shows that the ternary composite material BOI-UN1 / AgI4 is more conducive to inhibiting e - -h + The composite of the present invention shows that the ternary composite material has a very obvious effect. Figure 8b It can be seen that the radius of the arc of the ternary composite material BOI-UN1 / AgI4 is the smallest, indicating that the charge transfer resistance of the ternary composite material BOI-UN1 / AgI4 is the smallest, thus e - -h + The results of transient photocurrent test show that the transfer of - -h + The separation ability of Figure 8c It can be seen that the photocurrent response of the ternary composite material BOI-UN1 / AgI4 is higher, indicating that the - -h + Faster transfer, photogenerated - -h + For longer life.

[0049] The light response ability of the ternary composite material BOI-UN / Ag prepared in Example 6 was analyzed. The light response ability of AgI and the composite material BOI-UN1 / AgI4 was analyzed by solid ultraviolet diffuse reflectance. The results are as follows: Figures 9a-9b shown.

[0050] Figure 9a and Figure 9b The results of UV-visible DRS testing show the absorption edges of AgI and the composite material BOI-UN1 / AgI4 appear in the visible light region, with strong absorption bands in the 200-500 nm and 200-700 nm ranges, respectively. This indicates that AgI and BiOI further broaden the composite material's visible light response range.

[0051] In addition, the narrower the band gap of the material, the higher the photocatalytic efficiency. BiOI and the composite material BOI-UN1 / AgI4 are indirect band gap semiconductors according to their properties, that is, the n value is 2. Figure 9b As can be seen, and calculated through formula analysis, the HOMO-LUMO band gaps of AgI and the composite material BOI-UN1 / AgI4 are 2.14 eV and 1.89 eV, respectively. The BOI-UN1 / AgI4 composite material exhibits a significantly wider range of visible light response, with the absorption sideband shifting further to the right. Combined with the results of catalytic performance testing, this material demonstrates the best photocatalytic performance.

[0052] The above embodiments provide detailed descriptions of the implementation methods of the present invention. However, the present invention is not limited to the above embodiments. Various modifications can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. The above descriptions are merely preferred embodiments of the present invention and do not limit the scope of the present invention. Any equivalent structural changes made using the contents of the present invention description are included within the scope of the present invention.

Claims

1. A method for preparing a metal-organic framework ternary composite photocatalytic material based on a flower-like structure, characterized in that: The steps include: Step 1: Add a certain amount of Bi(NO3)3·5H2O powder into ethylene glycol and disperse it evenly to obtain solution I. Add KI powder into ethylene glycol and disperse it evenly to obtain solution II. Step 2: Mix solution I and solution II and stir them evenly, add a certain amount of UiO-66-NH2, transfer the mixture to a hydrothermal reactor for reaction, and perform post-treatment after the reaction to obtain the product BOI / UN; Step 3: Disperse the product BOI / UN obtained in step 2 in deionized water and stir evenly to obtain solution A; disperse silver nitrate powder in deionized water and stir evenly to obtain solution B; add solution B to solution A, stir and react under certain conditions; after the reaction is completed, let it stand and perform post-treatment to obtain the ternary composite photocatalytic material.

2. The method for preparing a metal-organic framework ternary composite photocatalytic material based on a flower-like structure according to claim 1, characterized in that: The molar ratio of Bi(NO3)3·5H2O powder to KI powder in step 1 is 1:

1.

3. The method for preparing a metal organic framework ternary composite photocatalytic material based on a flower-like structure according to claim 1, characterized in that: The reaction time of step 2 is 10-20 hours, and the reaction temperature is 100-200°C.

4. The method for preparing a metal-organic framework ternary composite photocatalytic material based on a flower-like structure according to claim 1, characterized in that: The mass of UiO-66-NH2 added in step 2 is 5% to 100% of the mass of Bi(NO3)3·5H2O powder.

5. The method for preparing a metal-organic framework ternary composite photocatalytic material based on a flower-like structure according to claim 1, characterized in that: The mass ratio of the silver nitrate powder to BOI / UN in step 3 is 1:1 to 8:

1.

6. The method for preparing a metal-organic framework ternary composite photocatalytic material based on a flower-like structure according to claim 1, characterized in that: The stirring reaction under certain conditions in step 3 specifically includes: vigorously stirring for 2 to 4 hours in a light-proof condition.

7. The method for preparing a metal organic framework ternary composite photocatalytic material based on a flower-like structure according to claim 1, characterized in that: The post-treatment in step 3 is as follows: the upper liquid layer is poured out, the lower solid layer is washed alternately with deionized water and anhydrous ethanol several times, and the washed product is dried in a constant temperature forced air drying oven at 80° C. for 12 h.

8. A metal-organic framework ternary composite photocatalytic material based on a flower-like structure obtained by the preparation method of a metal-organic framework ternary composite photocatalytic material based on a flower-like structure according to claim 1.

9. Use of the metal-organic framework ternary composite photocatalytic material constructed based on the flower-like structure according to claim 8 in photocatalytic degradation of TC.

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