Double-Z-type heterojunction photocatalytic composite material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of photocatalytic degradation, and particularly relates to a double-Z-type heterojunction photocatalytic composite material as well as a preparation method and application thereof. The preparation method of the double-Z-type heterojunction photocatalytic composite material comprises the following steps: by taking NH2-UiO-66 as a matrix, loading Bi2MoO6 on the surface of the NH2-UiO-66 to form a binary heterojunction, so as to obtain a Bi2MoO6 / NH2-UiO-66 composite material, and loading AgI on the surface of the Bi2MoO6 / NH2-UiO-66 composite material in situ to form a ternary heterojunction, so as to obtain the double-Z-type heterojunction photocatalytic composite material. On the basis of a heterogeneous photocatalytic oxidation reaction system, the photocatalytic double-Z-type heterojunction photocatalytic composite material which is efficient, stable and wide in spectral response range is obtained, the stability and durability of a catalyst are improved, and the photocatalytic double-Z-type heterojunction photocatalytic composite material can still keep good photocatalytic activity in the long-term use process and is suitable for complex and changeable water environments.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic degradation technology, specifically relating to a double Z-type heterojunction photocatalytic composite material, its preparation method, and its application. Background Technology

[0002] In recent years, with rapid social and industrial development, large quantities of antibiotics have been widely used and released into the natural environment, posing a serious threat to ecosystems and human health. Antibiotic pollutants, such as ofloxacin, are widely used in medicine and animal husbandry due to their highly effective antibacterial properties. However, the overuse and incomplete degradation of these antibiotics lead to their residues in the aquatic environment, increasing not only the risk of bacterial resistance but also causing potential long-term harm to aquatic ecosystems and human health. Therefore, developing effective treatment technologies to remove antibiotics and other recalcitrant organic pollutants has become an urgent priority.

[0003] Currently, traditional methods for treating antibiotic wastewater include physical, chemical, and biological methods. Physical methods, such as adsorption and membrane separation, can remove some pollutants, but they have limited treatment capacity and are difficult to completely degrade. Chemical oxidation methods, while having higher treatment efficiency, are costly and may generate secondary pollution. Biological methods are often limited by the recalcitrant nature of antibiotic wastewater, resulting in long treatment cycles and limited removal effects. Therefore, traditional treatment methods struggle to meet the requirements of high efficiency, low cost, and environmental friendliness.

[0004] To address the shortcomings of traditional methods, photocatalysis, as an advanced oxidation technology, has attracted widespread attention. Photocatalysis utilizes photogenerated electrons and holes generated by semiconductor materials under light irradiation to degrade organic pollutants through redox reactions, offering advantages such as mild reaction conditions and no secondary pollution. However, traditional photocatalysts such as TiO2 and ZnO have low utilization efficiency under natural light conditions due to their narrow spectral response range and responsiveness only to ultraviolet light. Furthermore, the high recombination rate of photogenerated electrons and holes severely limits photocatalytic efficiency. Single-material photocatalysts also suffer from performance and stability limitations, particularly after repeated cycles, where their photocatalytic activity significantly decreases, affecting their feasibility in practical applications.

[0005] Metal-organic frameworks (MOFs), as a novel type of porous material, possess advantages such as high specific surface area, abundant active sites, tunable band structure, and excellent modifiability, attracting widespread attention in the field of photocatalytic oxidation. UiO-66 is a three-dimensional framework structure synthesized using Zr as a metal cluster coordinated with terephthalic acid ligands. The Zr metal cluster has 12 coordination units, the highest coordination number among MOFs to date. Strong bonds between the metal center and the organic ligand endow UiO-66 with excellent thermal, chemical, and mechanical stability. However, UiO-66 alone suffers from high photogenerated carrier recombination rates and insufficient visible light response, resulting in slow and incomplete photodegradation, unsatisfactory photocatalytic activity, and inability to degrade antibiotics.

[0006] Based on this, researchers used UiO-66 as a matrix and functionalized it through amylation (-NH2), constructing binary composite materials to broaden its photoresponse range. Currently, the construction of binary NH2-UiO-66 catalytic composites such as NH2-UiO-66 / g-C3N4, NH2-UiO-66 / BiOBr, NH2-UiO-66 / CdS, and NH2-UiO-66 / Bi2MO6 has been extensively studied. Among them, Bi2MO6, in particular, has a moderate band gap, high photocatalytic activity, and the Mo element is environmentally friendly, non-toxic, harmless, and low in cost. However, due to its small specific surface area and few active sites, it still suffers from insufficient utilization of visible light and inadequate durability, limiting its practical application. Summary of the Invention

[0007] To address the aforementioned issues, this invention provides a dual-Z heterojunction photocatalytic composite material, its preparation method, and its application. Based on a heterogeneous photocatalytic oxidation reaction system, the invention optimizes the composite material's preparation process and structural design. This involves loading Bi2MoO6 onto the surface of NH2-UiO-66 to form a binary heterojunction, resulting in a Bi2MoO6 / NH2-UiO-66 composite material. Furthermore, AgI is in situ loaded onto the surface of the Bi2MoO6 / NH2-UiO-66 composite material to form a ternary heterojunction. This yields a photocatalytic dual-Z heterojunction photocatalytic composite material with high efficiency, stability, and a wide spectral response range. This improves the catalyst's stability and durability, enabling it to maintain good photocatalytic activity even during long-term use and adapt to complex and variable aquatic environments.

[0008] To achieve the above objectives, the specific technical solution provided by the present invention is as follows: The first objective of this invention is to provide a dual-Z heterojunction photocatalytic composite material, wherein the dual-Z heterojunction photocatalytic composite material is based on NH2-UiO-66 as a matrix, and Bi2MoO6 is loaded on the surface of NH2-UiO-66 to form a binary heterojunction, resulting in a Bi2MoO6 / NH2-UiO-66 composite material. Then, using the Bi2MoO6 / NH2-UiO-66 composite material as a support, AgI is loaded in situ on the surface of the Bi2MoO6 / NH2-UiO-66 composite material to form a ternary heterojunction, thus obtaining the dual-Z heterojunction photocatalytic composite material.

[0009] The second objective of this invention is to provide a method for preparing a double Z-type heterojunction photocatalytic composite material, comprising the following steps: S1. Dissolve soluble bismuth source and soluble molybdate in a solvent, add NH2-UiO-66, mix evenly, and then carry out a solvothermal reaction to obtain Bi2MoO6 / NH2-UiO-66 composite material.

[0010] S2. Ag-containing compounds are added to the Bi2MoO6 / NH2-UiO-66 composite material by in-situ deposition. + The solution forms a precursor, and stirring causes Ag to be adsorbed in situ on the surface of the Bi2MoO6 / NH2-UiO-66 composite material. + Then, while stirring, add dropwise a substance containing I to the precursor. - The solution, on the surface of Bi2MoO6 / NH2-UiO-66 composite material Ag + AgI was deposited in situ to form a double Z-type heterojunction photocatalytic composite material.

[0011] Furthermore, the mass ratio of Bi2MoO6 / NH2-UiO-66 composite material to AgI is 1:0.5 to 2.5.

[0012] Furthermore, containing Ag + The solution is an aqueous solution of AgNO3, which adsorbs Ag in situ. + The time is 30 to 60 minutes.

[0013] Furthermore, including I - The solution was an aqueous KI solution, and the time for in-situ deposition to form AgI was 2 to 4 hours.

[0014] Furthermore, the molar ratio of bismuth to molybdenum in the soluble bismuth source and the soluble molybdate is 2:1, the soluble bismuth source is Bi(NO3)3·5H2O, and the soluble molybdate is Na2MoO4·2H2O.

[0015] Furthermore, the molar mass ratio of Bi2MoO6 and NH2-UiO-66 is 2:0.05 to 0.06, the solvothermal reaction temperature is 150℃ to 170℃, and the time is 10h to 14h.

[0016] The third objective of this invention is to provide the application of the above-mentioned double Z-type heterojunction photocatalytic composite material in the photocatalytic degradation of organic pollutants in wastewater.

[0017] Furthermore, the organic pollutants are antibiotic-type pollutants.

[0018] Furthermore, the concentration of organic pollutants in the wastewater is 10 mg / L to 50 mg / L, the dosage of the double Z-type heterojunction photocatalytic composite material is 0.8 g / L, and the pH for photocatalytic degradation is 5 to 11.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a double Z-type heterojunction photocatalytic composite material, wherein Bi2MoO6 is loaded on the surface of NH2-UiO-66, tightly encapsulating NH2-UiO-66 to form a binary heterojunction, resulting in a Bi2MoO6 / NH2-UiO-66 composite material. Then, AgI, which has a visible light sensitization effect, is introduced into the Bi2MoO6 / NH2-UiO-66 composite material. Utilizing the photosensitization effect and surface plasmon resonance effect of AgI, not only is the visible light absorption capacity enhanced, but the band gap of the composite material can also be effectively adjusted. + AgI, prone to self-photocorrosion due to its reductive nature, is often composited with other semiconductors. Through surface plasmon resonance (SPR) effects, it promotes electron migration and separation, thereby further enhancing the photocatalytic performance of the composite material and suppressing the self-photocorrosion problem of AgI. This improves the utilization rate of solar energy, enabling it to exhibit excellent photocatalytic performance even under natural light conditions. Through structural design, the stability and durability of the catalyst are improved, allowing it to maintain good photocatalytic activity during long-term use and adapt to complex and variable aquatic environments. This composite material effectively overcomes the problems of existing catalytic composite materials, such as narrow visible light response range, limited photocatalytic performance, and activity decline after repeated use. It possesses high efficiency, stable photocatalytic ability, and good reusability, making it suitable for the photocatalytic degradation of various organic pollutants in water. Attached Figure Description

[0020] Figure 1 These are morphological and structural diagrams of the composite materials prepared in Example 1 and Comparative Examples 1 to 3 of the present invention. Figure 1In the image, (a) is a scanning electron microscope (SEM) of NH2-UiO-66, (b) is a scanning electron microscope (SEM) of Bi2MoO6, (c) is a scanning electron microscope (SEM) of AgI, (d) is a scanning electron microscope (SEM) of Example 1, (e) is a transmission electron microscope (TEM) of Example 1, and (f) is a partial magnification of (e).

[0021] Figure 2 This is an XPS image of the composite material prepared in Example 3 of the present invention. Figure 2 In the image, (a) is the full spectrum, (b) is the Zr 3d spectrum, (c) is the Mo 3d spectrum, (d) is the Bi 4f spectrum, (e) is the Ag 3d spectrum, and (f) is the I 3d spectrum.

[0022] Figure 3 The images show the photoelectrochemical analysis of the composite materials prepared in Example 3 and Comparative Examples 1 to 4 of this invention. Figure 3 (a) is the transient photocurrent response diagram, (b) is the electrochemical impedance spectroscopy diagram, and (c) is the fluorescence spectrum diagram.

[0023] Figure 4 The graphs show the pollutant degradation performance of the catalytic composite materials prepared in Examples 1 to 5 and Comparative Examples 1 to 5 of the present invention. Figure 4 In the middle (a), the degradation curves of NOR pollutants by the catalytic composite materials prepared in Examples 1 to 5 and Comparative Examples 1 to 5 are shown. In the middle (b), the degradation curves of different pollutants by the catalytic composite material prepared in Example 3 are shown.

[0024] Figure 5 The graph shows the performance of the catalytic composite material prepared in Example 3 of this invention on pollutant degradation under different pH conditions.

[0025] Figure 6 This is a stability diagram of the catalytic composite material prepared in Example 3 of the present invention for pollutant degradation. Detailed Implementation

[0026] 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 in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] Traditional semiconductor photocatalysts, such as TiO2 and ZnO, as well as single UiO-66 materials, are prone to photorecombination of photogenerated electrons and holes during photocatalysis, resulting in a limited absorption range for visible light and an inability to fully utilize solar energy. This leads to low photocatalytic efficiency and limits their application under natural light conditions. While some binary composite materials have broadened the photoresponse range by introducing bismuth-based semiconductor materials such as NH2-UiO-66 / Bi2MO6, they still suffer from insufficient utilization of visible light. Over long-term use, they are prone to structural damage or deactivation of active sites, leading to poor catalyst stability and difficulty in meeting practical application requirements. This stability issue is particularly pronounced in complex and variable aquatic environments.

[0029] Based on this, this invention, grounded in a heterogeneous photocatalytic oxidation reaction system, optimizes the preparation process and structural design of the composite material. By introducing AgI, which exhibits visible light sensitization, to construct a ternary heterojunction, the band gap of the photocatalytic composite material is optimized, promoting the effective separation of photogenerated electrons and holes. This overcomes the problems of existing catalysts, such as narrow visible light response range, limited photocatalytic performance, and decreased activity after repeated use. Specifically, this invention provides a double-Z heterojunction photocatalytic composite material. This material uses NH2-UiO-66 as a matrix, with Bi2MoO6 loaded on the NH2-UiO-66 surface to form a binary heterojunction, resulting in a Bi2MoO6 / NH2-UiO-66 composite material. Then, using the Bi2MoO6 / NH2-UiO-66 composite material as a support, AgI is in-situ loaded on the surface of the Bi2MoO6 / NH2-UiO-66 composite material to form a ternary heterojunction, thus obtaining the double-Z heterojunction photocatalytic composite material.

[0030] It should be noted that the double Z-type heterojunction photocatalytic composite material provided by this invention comprises Bi2MoO6 loaded on the surface of NH2-UiO-66, tightly encapsulating NH2-UiO-66 to form a binary heterojunction, resulting in a Bi2MoO6 / NH2-UiO-66 composite material. Then, AgI, which has a visible light sensitization effect, is introduced into the Bi2MoO6 / NH2-UiO-66 composite material. Utilizing the photosensitization effect and surface plasmon resonance effect of AgI, not only is the visible light absorption capacity enhanced, but the band gap of the composite material can also be effectively adjusted. +AgI, prone to self-photocorrosion due to its reductive nature, is often composited with other semiconductors. Through surface plasmon resonance (SPR) effects, it promotes electron migration and separation, thereby further enhancing the photocatalytic performance of the composite material and suppressing the self-photocorrosion problem of AgI. This improves the utilization rate of solar energy, enabling it to exhibit excellent photocatalytic performance even under natural light conditions. Through structural design, the stability and durability of the catalyst are improved, allowing it to maintain good photocatalytic activity during long-term use and adapt to complex and variable aquatic environments. This composite material effectively overcomes the problems of existing catalytic composite materials, such as narrow visible light response range, limited photocatalytic performance, and activity decline after repeated use. It possesses high efficiency, stable photocatalytic ability, and good reusability, making it suitable for the photocatalytic degradation of various organic pollutants in water.

[0031] On the other hand, the present invention also provides a method for preparing a double Z-type heterojunction photocatalytic composite material, comprising the following steps: S1. Dissolve soluble bismuth source and soluble molybdate in a solvent, add NH2-UiO-66, mix evenly, and then carry out a solvothermal reaction to obtain Bi2MoO6 / NH2-UiO-66 composite material.

[0032] S2. Ag-containing compounds are added to the Bi2MoO6 / NH2-UiO-66 composite material by in-situ deposition. + The solution forms a precursor, and stirring causes Ag to be adsorbed in situ on the surface of the Bi2MoO6 / NH2-UiO-66 composite material. + Then, while stirring, add dropwise a substance containing I to the precursor. - The solution, on the surface of Bi2MoO6 / NH2-UiO-66 composite material Ag + AgI was deposited in situ to form a double Z-type heterojunction photocatalytic composite material.

[0033] It should be noted that this invention uses Bi2MoO6 / NH2-UiO-66 composite material as the matrix, and Ag is adsorbed on the surface. + Then add I - In-situ precipitation forms AgI solid particles that adhere to the surface of Bi2MoO6 / NH2-UiO-66. Utilizing the photosensitization effect and surface plasmon resonance effect of AgI, not only is the visible light absorption enhanced, but the band gap of the composite material can also be effectively adjusted. + AgI is prone to self-photocorrosion and is often combined with other semiconductors. Through the surface plasmon resonance (SPR) effect, it promotes the migration and separation of electrons, thereby further improving the photocatalytic performance of the composite material and suppressing the problem of AgI self-photocorrosion. This improves the utilization rate of solar energy and enables it to exhibit excellent photocatalytic performance under natural light conditions.

[0034] In one embodiment, the mass ratio of Bi2MoO6 / NH2-UiO-66 composite material to AgI is 1:0.5 to 2.5.

[0035] In one embodiment, containing Ag + The solution is an aqueous solution of AgNO3. In-situ adsorption occurs in the dark and in the absence of light. + The time is 30 to 60 minutes.

[0036] In one embodiment, containing I - The solution was an aqueous KI solution, and in-situ deposition was carried out in the dark. The time for in-situ deposition to form AgI was 2h to 4h.

[0037] In one embodiment, the molar ratio of bismuth to molybdenum in the soluble bismuth source and the soluble molybdate is 2:1, the soluble bismuth source is Bi(NO3)3·5H2O, and the soluble molybdate is Na2MoO4·2H2O. In this invention, the soluble bismuth source can also be a soluble bismuth salt such as BiCl3 or Bi(CH3COO)3.

[0038] In some embodiments, the preparation method of NH2-UiO-66 includes the following steps: A one-step solvothermal method was used to disperse ZrCl4 and 2-aminoterephthalic acid in a solvent. After stirring and dispersing evenly, the mixture was subjected to a solvothermal reaction at 110℃~130℃ for 22h~26h. After the reaction was completed, the mixture was centrifuged, washed and dried to obtain NH2-UiO-66. The molar ratio of ZrCl4 to 2-aminoterephthalic acid was 1:1.

[0039] In one embodiment, the molar ratio of Bi₂MoO₆ to NH₂-UiO₆ is 2:0.05–0.06, the solvothermal reaction temperature is 150°C–170°C, and the reaction time is 10–14 h. In a preferred embodiment, after the solvothermal reaction is completed, the reaction product is thoroughly washed with deionized water and anhydrous ethanol, and then dried at 60°C for 8 h to obtain the Bi₂MoO₆ / NH₂-UiO₆ composite catalyst.

[0040] Furthermore, this invention provides the application of the aforementioned double-Z heterojunction photocatalytic composite material in the photocatalytic degradation of organic pollutants in wastewater. The organic pollutants are antibiotics; in a preferred embodiment, the antibiotics are rhodamine B, tetracycline, or norfloxacin.

[0041] In one embodiment, the concentration of organic pollutants in the wastewater is 10 mg / L to 50 mg / L, the amount of the double Z-type heterojunction photocatalytic composite material is 0.8 g / L, and the pH for photocatalytic degradation is 5 to 11.

[0042] The following specific examples will provide further explanation.

[0043] Example 1 A method for preparing a double Z-type heterojunction photocatalytic composite material includes the following steps: S1. Using a one-step solvothermal method, 1.0 mmol of ZrCl4 and 1.0 mmol of 2-aminoterephthalic acid were dispersed in 20 mL of N,N-dimethylformamide and magnetically stirred for 30 min to fully dissolve, forming a reaction solution. The reaction solution was placed in a 50 mL Teflon-lined stainless steel high-pressure reactor and heated in a 120 °C forced-air drying oven for 24 h to allow the reaction to proceed. After the reaction was completed, the reaction system was allowed to cool naturally to room temperature to obtain the reaction product. The reaction product was separated at 8000 r / min for 4 min to obtain a pale yellow product. After thorough alternating washing with deionized water and anhydrous ethanol, it was dried under vacuum at 80 °C for 12 h to obtain NH2-UiO-66.

[0044] S2. Disperse 4 mmol of Bi(NO3)3·5H2O and 2 mmol of Na2MoO4·2H2O into 20 mL of ethylene glycol, and then slowly add 40 mL of anhydrous ethanol to form a mixture. Add 100 mg of NH2-UiO-66 to the mixture and stir for 30 min to dissolve it completely to form a reaction solution. Transfer the reaction solution to a 100 mL Teflon-lined stainless steel high-pressure reactor and heat it at 160 °C for 12 h in a forced-air drying oven. After the reaction is completed, cool it to room temperature, wash it thoroughly with deionized water and anhydrous ethanol alternately, and then dry it in a vacuum drying oven at 60 °C for 8 h to obtain the Bi2MoO6 / NH2-UiO-66 composite material.

[0045] S3. Using the in-situ deposition method, 0.0724 g of AgNO3 was completely dissolved in 20 mL of pure water, and then 100 mg of Bi2MoO6 / NH2-UiO-66 composite material was added. After sonication for a few minutes, the mixture was stirred in the dark for 30 minutes to allow Ag to be adsorbed in situ on the surface of the Bi2MoO6 / NH2-UiO-66 composite material. + Bi2MoO6 / NH2-UiO-66 / Ag was obtained. + Mixed system. Dissolve 0.0708 g of KI in 10 mL of water to obtain a KI aqueous solution. While stirring rapidly, add 10 mL of the KI aqueous solution dropwise to Bi₂MoO₆ / NH₂-UiO₆ / Ag. +After the addition of the mixture was complete, the mixture was stirred for 3 hours in the dark. The product was collected by centrifugation, washed thoroughly with deionized water and anhydrous ethanol by alternating centrifugation, and dried at 60°C for 5 hours to obtain the Bi2MoO6 / NH2-UiO-66 / AgI composite material, which is a double Z-type heterojunction photocatalytic composite material, named BNUA-0.5.

[0046] Example 2 A method for preparing a double Z-type heterojunction photocatalytic composite material includes the following steps: S1. Using a one-step solvothermal method, 1.0 mmol of ZrCl4 and 1.0 mmol of 2-aminoterephthalic acid were dispersed in 20 mL of N,N-dimethylformamide and magnetically stirred for 30 min to fully dissolve them, forming a reaction solution. The reaction solution was placed in a 50 mL Teflon-lined stainless steel high-pressure reactor and heated in a 120 °C forced-air drying oven for 24 h to allow the reaction to proceed. After the reaction was completed, the reaction system was allowed to cool naturally to room temperature to obtain the reaction product. The reaction product was separated at 8000 r / min for 4 min to obtain a pale yellow product. After thorough alternating washing with deionized water and anhydrous ethanol, it was dried under vacuum at 80 °C for 12 h to obtain NH2-UiO-66.

[0047] S2. Disperse 4 mmol of Bi(NO3)3·5H2O and 2 mmol of Na2MoO4·2H2O into 20 mL of ethylene glycol, and then slowly add 40 mL of anhydrous ethanol to form a mixture. Add 100 mg of NH2-UiO-66 to the mixture and stir for 30 min to dissolve it completely to form a reaction solution. Transfer the reaction solution to a 100 mL Teflon-lined stainless steel high-pressure reactor and heat it at 160 °C for 12 h in a forced-air drying oven. After the reaction is completed, cool it to room temperature, wash it thoroughly with deionized water and anhydrous ethanol alternately, and then dry it in a vacuum drying oven at 60 °C for 8 h to obtain the Bi2MoO6 / NH2-UiO-66 composite material.

[0048] S3. Using the in-situ deposition method, 0.1447 g of AgNO3 was completely dissolved in 20 mL of pure water, and then 100 mg of Bi2MoO6 / NH2-UiO-66 composite material was added. After sonication for a few minutes, the mixture was stirred in the dark for 30 minutes to allow Ag to be adsorbed in situ on the surface of the Bi2MoO6 / NH2-UiO-66 composite material. + Bi2MoO6 / NH2-UiO-66 / Ag was obtained. + Mixed system. Dissolve 0.1415 g of KI in 10 mL of water to obtain a KI aqueous solution. While stirring rapidly, add 10 mL of the KI aqueous solution dropwise to Bi₂MoO₆ / NH₂-UiO₄⁶ / Ag.+ After the addition of the mixture was complete, the mixture was stirred for 3 hours in the dark. The product was collected by centrifugation, washed thoroughly with deionized water and anhydrous ethanol by alternating centrifugation, and dried at 60°C for 5 hours to obtain the Bi2MoO6 / NH2-UiO-66 / AgI composite material, which is a double Z-type heterojunction photocatalytic composite material, named BNUA-1.

[0049] Example 3 A method for preparing a double Z-type heterojunction photocatalytic composite material includes the following steps: S1. Using a one-step solvothermal method, 1.0 mmol of ZrCl4 and 1.0 mmol of 2-aminoterephthalic acid were dispersed in 20 mL of N,N-dimethylformamide and magnetically stirred for 30 min to fully dissolve them, forming a reaction solution. The reaction solution was placed in a 50 mL Teflon-lined stainless steel high-pressure reactor and heated in a 120 °C forced-air drying oven for 24 h to allow the reaction to proceed. After the reaction was completed, the reaction system was allowed to cool naturally to room temperature to obtain the reaction product. The reaction product was separated at 8000 r / min for 4 min to obtain a pale yellow product. After thorough alternating washing with deionized water and anhydrous ethanol, it was dried under vacuum at 80 °C for 12 h to obtain NH2-UiO-66.

[0050] S2. Disperse 4 mmol of Bi(NO3)3·5H2O and 2 mmol of Na2MoO4·2H2O into 20 mL of ethylene glycol, and then slowly add 40 mL of anhydrous ethanol to form a mixture. Add 100 mg of NH2-UiO-66 to the mixture and stir for 30 min to dissolve it completely to form a reaction solution. Transfer the reaction solution to a 100 mL Teflon-lined stainless steel high-pressure reactor and heat it at 160 °C for 12 h in a forced-air drying oven. After the reaction is completed, cool it to room temperature, wash it thoroughly with deionized water and anhydrous ethanol alternately, and then dry it in a vacuum drying oven at 60 °C for 8 h to obtain the Bi2MoO6 / NH2-UiO-66 composite material.

[0051] S3. Using the in-situ deposition method, 0.2171 g of AgNO3 was completely dissolved in 20 mL of pure water, and then 100 mg of Bi2MoO6 / NH2-UiO-66 composite material was added. After sonication for a few minutes, the mixture was stirred in the dark for 30 minutes to allow Ag to be adsorbed in situ on the surface of the Bi2MoO6 / NH2-UiO-66 composite material. + Bi2MoO6 / NH2-UiO-66 / Ag was obtained. +Mixed system. Dissolve 0.2122 g of KI in 10 mL of water to obtain a KI aqueous solution. While stirring rapidly, add 10 mL of the KI aqueous solution dropwise to Bi₂MoO₆ / NH₂-UiO₄⁻ / Ag⁻ + After the addition of the mixture is complete, the mixture is stirred for 3 hours in the dark. The product is collected by centrifugation, washed thoroughly with deionized water and anhydrous ethanol by alternating centrifugation, and dried at 60°C for 5 hours to obtain the Bi2MoO6 / NH2-UiO-66 / AgI composite material, which is a double Z-type heterojunction photocatalytic composite material, named BNUA-1.5.

[0052] Example 4 A method for preparing a double Z-type heterojunction photocatalytic composite material includes the following steps: S1. Using a one-step solvothermal method, 1.0 mmol of ZrCl4 and 1.0 mmol of 2-aminoterephthalic acid were dispersed in 20 mL of N,N-dimethylformamide and magnetically stirred for 30 min to fully dissolve them, forming a reaction solution. The reaction solution was placed in a 50 mL Teflon-lined stainless steel high-pressure reactor and heated in a 120 °C forced-air drying oven for 24 h to allow the reaction to proceed. After the reaction was completed, the reaction system was allowed to cool naturally to room temperature to obtain the reaction product. The reaction product was separated at 8000 r / min for 4 min to obtain a pale yellow product. After thorough alternating washing with deionized water and anhydrous ethanol, it was dried under vacuum at 80 °C for 12 h to obtain NH2-UiO-66.

[0053] S2. Disperse 4 mmol of Bi(NO3)3·5H2O and 2 mmol of Na2MoO4·2H2O into 20 mL of ethylene glycol, and then slowly add 40 mL of anhydrous ethanol to form a mixture. Add 100 mg of NH2-UiO-66 to the mixture and stir for 30 min to dissolve it completely to form a reaction solution. Transfer the reaction solution to a 100 mL Teflon-lined stainless steel high-pressure reactor and heat it at 160 °C for 12 h in a forced-air drying oven. After the reaction is completed, cool it to room temperature, wash it thoroughly with deionized water and anhydrous ethanol alternately, and then dry it in a vacuum drying oven at 60 °C for 8 h to obtain the Bi2MoO6 / NH2-UiO-66 composite material.

[0054] S3. Using the in-situ deposition method, 0.2895 g of AgNO3 was completely dissolved in 20 mL of pure water, and then 100 mg of Bi2MoO6 / NH2-UiO-66 composite material was added. After sonication for a few minutes, the mixture was stirred in the dark for 30 minutes to allow Ag to be adsorbed in situ on the surface of the Bi2MoO6 / NH2-UiO-66 composite material. + Bi2MoO6 / NH2-UiO-66 / Ag was obtained.+ Mixed system. Dissolve 0.2829 g of KI in 10 mL of water to obtain a KI aqueous solution. While stirring rapidly, add 10 mL of the KI aqueous solution dropwise to Bi₂MoO₆ / NH₂-UiO₆ / Ag. + After the addition of the mixture was complete, the mixture was stirred for 3 hours in the dark. The product was collected by centrifugation, washed thoroughly with deionized water and anhydrous ethanol by alternating centrifugation, and dried at 60°C for 5 hours to obtain the Bi2MoO6 / NH2-UiO-66 / AgI composite material, which is a double Z-type heterojunction photocatalytic composite material, named BNUA-2.

[0055] Example 5 A method for preparing a double Z-type heterojunction photocatalytic composite material includes the following steps: S1. Using a one-step solvothermal method, 1.0 mmol of ZrCl4 and 1.0 mmol of 2-aminoterephthalic acid were dispersed in 20 mL of N,N-dimethylformamide and magnetically stirred for 30 min to fully dissolve them, forming a reaction solution. The reaction solution was placed in a 50 mL Teflon-lined stainless steel high-pressure reactor and heated in a 120 °C forced-air drying oven for 24 h to allow the reaction to proceed. After the reaction was completed, the reaction system was allowed to cool naturally to room temperature to obtain the reaction product. The reaction product was separated at 8000 r / min for 4 min to obtain a pale yellow product. After thorough alternating washing with deionized water and anhydrous ethanol, it was dried under vacuum at 80 °C for 12 h to obtain NH2-UiO-66.

[0056] S2. Disperse 4 mmol of Bi(NO3)3·5H2O and 2 mmol of Na2MoO4·2H2O into 20 mL of ethylene glycol, and then slowly add 40 mL of anhydrous ethanol to form a mixture. Add 100 mg of NH2-UiO-66 to the mixture and stir for 30 min to dissolve it completely to form a reaction solution. Transfer the reaction solution to a 100 mL Teflon-lined stainless steel high-pressure reactor and heat it at 160 °C for 12 h in a forced-air drying oven. After the reaction is completed, cool it to room temperature, wash it thoroughly with deionized water and anhydrous ethanol alternately, and then dry it in a vacuum drying oven at 60 °C for 8 h to obtain the Bi2MoO6 / NH2-UiO-66 composite material.

[0057] S3. Using the in-situ deposition method, 0.3618 g of AgNO3 was completely dissolved in 20 mL of pure water, and then 100 mg of Bi2MoO6 / NH2-UiO-66 composite material was added. After sonication for a few minutes, the mixture was stirred in the dark for 30 minutes to allow Ag to be adsorbed in situ on the surface of the Bi2MoO6 / NH2-UiO-66 composite material. +Bi2MoO6 / NH2-UiO-66 / Ag was obtained. + Mixed system. Dissolve 0.3536 g of KI in 10 mL of water to obtain a KI aqueous solution. While stirring rapidly, add 10 mL of the KI aqueous solution dropwise to Bi₂MoO₆ / NH₂-UiO₆ / Ag. + After the addition of the mixture to the mixture was complete, the mixture was stirred for 3 hours in the dark. The product was collected by centrifugation, washed thoroughly with deionized water and anhydrous ethanol by alternating centrifugation, and dried at 60°C for 5 hours to obtain the Bi2MoO6 / NH2-UiO-66 / AgI composite material, which is a double Z-type heterojunction photocatalytic composite material, named BNUA-2.5.

[0058] Comparative Example 1 A method for preparing a catalytic composite material includes the following steps: A one-step solvothermal method was used to disperse 1.0 mmol of ZrCl4 and 1.0 mmol of 2-aminoterephthalic acid in 20 mL of N,N-dimethylformamide. The mixture was magnetically stirred for 30 min to ensure complete dissolution and form a reaction solution. The reaction solution was placed in a 50 mL Teflon-lined stainless steel autoclave and heated in a 120 °C forced-air drying oven for 24 h to allow the reaction to proceed. After the reaction was completed, the reaction system was allowed to cool naturally to room temperature to obtain the reaction product. The reaction product was separated at 8000 r / min for 4 min to obtain a pale yellow product. After thorough alternating washing with deionized water and anhydrous ethanol, the product was dried under vacuum at 80 °C for 12 h to obtain NH2-UiO-66.

[0059] Comparative Example 2 A method for preparing a catalytic composite material includes the following steps: 4 mmol of Bi(NO3)3·5H2O and 2 mmol of Na2MoO4·2H2O were dispersed in 20 mL of ethylene glycol, and then 40 mL of anhydrous ethanol was slowly added to form a reaction solution. The reaction solution was transferred to a 100 mL Teflon-lined stainless steel high-pressure reactor and heated at 160 °C for 12 h in a forced-air drying oven. After the reaction was completed, the mixture was cooled to room temperature and thoroughly washed with deionized water and anhydrous ethanol alternately. Then, it was dried in a vacuum drying oven at 60 °C for 8 h to obtain the Bi2MoO6 composite material.

[0060] Comparative Example 3 A method for preparing a catalytic composite material includes the following steps: An in-situ deposition method was used. 0.0724 g of AgNO3 was completely dissolved in 20 mL of pure water, and 0.0708 g of KI was dissolved in 10 mL of water to obtain a KI aqueous solution. Under rapid stirring, 10 mL of the KI aqueous solution was added dropwise to the AgNO3 system. After the addition was complete, the mixture was stirred for 3 hours in the dark. The product was collected by centrifugation, washed thoroughly with deionized water and anhydrous ethanol alternately by centrifugation, and dried at 60 °C for 5 hours to obtain the AgI material.

[0061] Comparative Example 4 A method for preparing a Bi2MoO6 / NH2-UiO-66 catalytic composite material includes the following steps: S1. Using a one-step solvothermal method, 1.0 mmol of ZrCl4 and 1.0 mmol of 2-aminoterephthalic acid were dispersed in 20 mL of N,N-dimethylformamide and magnetically stirred for 30 min to fully dissolve them, forming a reaction solution. The reaction solution was placed in a 50 mL Teflon-lined stainless steel high-pressure reactor and heated in a 120 °C forced-air drying oven for 24 h to allow the reaction to proceed. After the reaction was completed, the reaction system was allowed to cool naturally to room temperature to obtain the reaction product. The reaction product was separated at 8000 r / min for 4 min to obtain a pale yellow product. After thorough alternating washing with deionized water and anhydrous ethanol, it was dried under vacuum at 80 °C for 12 h to obtain NH2-UiO-66.

[0062] S2. Disperse 4 mmol of Bi(NO3)3·5H2O and 2 mmol of Na2MoO4·2H2O into 20 mL of ethylene glycol, and then slowly add 40 mL of anhydrous ethanol to form a mixture. Add 100 mg of NH2-UiO-66 to the mixture and stir for 30 min to dissolve it completely to form a reaction solution. Transfer the reaction solution to a 100 mL Teflon-lined stainless steel high-pressure reactor and heat it at 160 °C for 12 h in a forced-air drying oven. After the reaction is completed, cool it to room temperature, wash it thoroughly with deionized water and anhydrous ethanol alternately, and then dry it in a vacuum drying oven at 60 °C for 8 h to obtain the Bi2MoO6 / NH2-UiO-66 composite material, named BNU-100.

[0063] Comparative Example 5 A method for preparing a catalytic composite material includes the following steps: S1. Disperse 4 mmol of Bi(NO3)3·5H2O and 2 mmol of Na2MoO4·2H2O into 20 mL of ethylene glycol, and then slowly add 40 mL of anhydrous ethanol to form a reaction solution. Transfer the reaction solution to a 100 mL Teflon-lined stainless steel high-pressure reactor and heat it at 160 °C for 12 h in a forced-air drying oven. After the reaction is completed, cool it to room temperature, wash it thoroughly with deionized water and anhydrous ethanol alternately, and then dry it in a vacuum drying oven at 60 °C for 8 h to obtain Bi2MoO6 material.

[0064] Using an in-situ deposition method, 0.0724 g of AgNO3 was completely dissolved in 20 mL of pure water, and then 100 mg of Bi2MoO6 material was added. After sonication for a few minutes, the mixture was stirred in the dark for 30 minutes to allow Ag to be adsorbed in situ on the surface of the Bi2MoO6 material. + Bi2MoO6 / NH2-UiO-66 / Ag was obtained. + Mixed system. Dissolve 0.0708 g KI in 10 mL of water to obtain a KI aqueous solution. While stirring rapidly, add 10 mL of the KI aqueous solution dropwise to the Bi₂MoO₆ / Ag mixture. + After the addition of the mixture was complete, the mixture was stirred for 3 hours in the dark. The product was collected by centrifugation, washed thoroughly with deionized water and anhydrous ethanol by alternating centrifugation, and dried at 60°C for 5 hours to obtain the Bi2MoO6 / AgI composite material.

[0065] The structures of the Bi2MoO6 / NH2-UiO-66 / AgI composite materials prepared in Examples 1 to 5 and the catalytic composite materials prepared in Comparative Examples 1 to 5 were tested. Since the structures of the Bi2MoO6 / NH2-UiO-66 / AgI composite materials prepared in Examples 1 to 5 are basically similar, the Bi2MoO6 / NH2-UiO-66 / AgI composite material prepared in Example 1 will be used for illustration.

[0066] Figure 1 These are morphological and structural diagrams of the composite materials prepared in Example 1 and Comparative Examples 1 to 3 of the present invention. Figure 1 In the image, (a) is a scanning electron microscope (SEM) of NH2-UiO-66, (b) is a scanning electron microscope (SEM) of Bi2MoO6, (c) is a scanning electron microscope (SEM) of AgI, (d) is a scanning electron microscope (SEM) of Example 1, (e) is a transmission electron microscope (TEM) of Example 1, and (f) is a magnified view of a portion of (e). Figure 1 As shown, the composite material Bi2MoO6 tightly encapsulates NH2-UiO-66, and AgI is successfully loaded onto its surface. The synthesis process reduced AgI aggregation, allowing AgI to adhere to the surface of the binary material in a smaller size. Figure 1Figure (f) clearly shows the heterojunction boundary and the lattice fringes of each component, thus proving the successful formation of the heterojunction.

[0067] Figure 2 This is an XPS image of the composite material prepared in Example 3 of the present invention. Figure 2 In the diagram, (a) is the full spectrum, (b) is the Zr 3d spectrum, (c) is the Mo 3d spectrum, (d) is the Bi 4f spectrum, (e) is the Ag 3d spectrum, and (f) is the I 3d spectrum. Figure 2 As shown, the full spectrum results indicate that the sample contains eight elements: C, N, O, Zr, Bi, Mo, Ag, and I. Compared to the original single component, the fitting peaks of Zr, Ag, and I in the composite material shift towards the direction of decreasing binding energy, indicating an increase in electron density. Conversely, the fitting peaks of Bi and Mo shift towards the direction of increasing binding energy, indicating a decrease in electron density. This suggests that the components are bonded together through electronic interactions to form a heterostructure, rather than a simple physical mixture.

[0068] Figure 3 The images show the photoelectrochemical analysis of the composite materials prepared in Example 3 and Comparative Examples 1 to 4 of this invention. Figure 3 In the diagram, (a) is the transient photocurrent response, (b) is the electrochemical impedance spectroscopy, and (c) is the fluorescence spectrum. Figure 3 As shown, the photocurrent intensity of the composite material is significantly improved according to the transient photocurrent response test; the impedance of the composite material is reduced and the conductivity is improved according to the electrochemical impedance spectroscopy test; and the recombination probability of photogenerated electron-hole pairs in the composite material is further reduced and the lifetime of photogenerated carriers is significantly extended according to the fluorescence spectroscopy test.

[0069] The Bi₂MoO₆ / NH₂-UiO₆ / AgI composite materials prepared in Examples 1-5 and the catalytic composite materials prepared in Comparative Examples 1-5 were used for photocatalytic degradation of organic pollutants in wastewater. The specific steps included: 200 mL of norfloxacin (NOR: 20 mg / L) solution was measured into a quartz reaction tube, and then 0.8 g / L of the Bi₂MoO₆ / NH₂-UiO₆ / AgI composite materials prepared in Examples 1-5 and the catalytic composite materials prepared in Comparative Examples 1-5 were added respectively. The mixture was first subjected to dark adsorption for 30 min in a dark environment to reach adsorption equilibrium. Then, the reaction tube was transferred to a photocatalytic reaction device, and irradiated with a 500W xenon lamp as a simulated sunlight source. Samples were taken every 20 min. After centrifugation and dilution (2.5 times), the absorbance of the solution was measured using a UV-Vis spectrophotometer at a wavelength of 293 nm. The NOR concentration could be calculated based on the absorbance. The steps for other pollutants are the same, the difference being that tetracycline (TC) is measured at wavelengths of 278 nm and 357 nm using a UV-Vis spectrophotometer, while rhodamine B (RhB) is measured at a wavelength of 554 nm using a visible spectrophotometer.

[0070] Figure 4 The graphs show the pollutant degradation performance of the catalytic composite materials prepared in Examples 1 to 5 and Comparative Examples 1 to 5 of the present invention. Figure 4 In Figure (a), the degradation curves of NOR pollutants by the catalytic composite materials prepared in Examples 1-5 and Comparative Examples 1-5 are shown. In Figure (b), the degradation curves of different pollutants by the catalytic composite material prepared in Example 3 are shown. Figure 4 As shown in (a), when only a single NH4+ is added... 2- In the cases of UiO-66, Bi2MoO6, and AgI, the degradation rates at 60 min were 41.1%, 87.6%, and 54.5%, respectively. After ternary composites, the degradation rates of BNUA-0.5, BNUA-1, BNUA-1.5, BNUA-2, and BNUA-2.5 were 95.9%, 95.8%, 96.7%, 94.0%, and 92.2%, respectively. Compared with single materials and binary composites, the degradation performance of the composites was improved, with BNUA-1.5 showing the highest degradation rate. The photocatalytic activity of the catalyst was more accurately evaluated using reaction kinetic constants. Calculations showed that the degradation rate constant k of BNUA-1.5 during NOR degradation was 0.07028·min. -1 The kinetic constants of these catalysts were 26.7 times, 24 times, 11.3 times, and 1.5 times that of NH2-UiO-66, Bi2MoO6, AgI, and BNU-100, respectively, demonstrating excellent photocatalytic activity. Figure 4As shown in (b), after 60 min of illumination, the degradation rate of TC by BNUA-1.5 catalytic composite material was 94.4%, the degradation rate of RhB was 99.7%, and the degradation rate of NOR was 80.2%, indicating that BNUA-1.5 catalytic composite material has a good degradation effect on different types of pollutants.

[0071] Figure 5 The graph shows the performance of the catalytic composite material prepared in Example 3 of this invention on pollutant degradation under different pH conditions. Figure 5 As shown, the pH range of the composite material is significantly broadened, enabling efficient photocatalytic degradation of organic pollutants within a pH range of 5 to 11.

[0072] Figure 6 This is a stability diagram of the catalytic composite material prepared in Example 3 of the present invention for pollutant degradation. Figure 6 As shown, the catalytic composite material maintained good stability after 5 cycles of testing.

[0073] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, it is intended to include any modifications and variations that fall within the scope of the claims and their equivalents.

Claims

1. A double Z-type heterojunction photocatalytic composite material, characterized in that, The dual-Z heterojunction photocatalytic composite material is obtained by loading Bi2MoO6 on the surface of NH2-UiO-66 as a matrix to form a binary heterojunction, resulting in Bi2MoO6 / NH2-UiO-66 composite material. Then, using the Bi2MoO6 / NH2-UiO-66 composite material as a support, AgI is loaded in situ on the surface of the Bi2MoO6 / NH2-UiO-66 composite material to form a ternary heterojunction, thus obtaining the dual-Z heterojunction photocatalytic composite material.

2. A method for preparing the double Z-type heterojunction photocatalytic composite material according to claim 1, characterized in that, Includes the following steps: A soluble bismuth source and a soluble molybdate were dissolved in a solvent, and NH2-UiO-66 was added. After mixing evenly, a solvothermal reaction was carried out to obtain a Bi2MoO6 / NH2-UiO-66 composite material. Ag-containing compounds were added to the Bi2MoO6 / NH2-UiO-66 composite material by in-situ deposition. + The solution forms a precursor, and stirring causes Ag to be adsorbed in situ on the surface of the Bi2MoO6 / NH2-UiO-66 composite material. + Then, while stirring, add dropwise a substance containing I to the precursor. - The solution, on the surface of Bi2MoO6 / NH2-UiO-66 composite material Ag + AgI was deposited in situ to form a double Z-type heterojunction photocatalytic composite material.

3. The method for preparing the double Z-type heterojunction photocatalytic composite material according to claim 2, characterized in that, The mass ratio of Bi2MoO6 / NH2-UiO-66 composite material to AgI is 1:0.5 to 2.

5.

4. The method for preparing the double Z-type heterojunction photocatalytic composite material according to claim 2 is characterized in that, Contains Ag + The solution is an aqueous solution of AgNO3, which adsorbs Ag in situ. + The time is 30 to 60 minutes.

5. The method for preparing the double Z-type heterojunction photocatalytic composite material according to claim 2, characterized in that, Contains I - The solution was an aqueous KI solution, and the time for in-situ deposition to form AgI was 2 to 4 hours.

6. The method for preparing the double Z-type heterojunction photocatalytic composite material according to claim 2, characterized in that, The molar ratio of bismuth to molybdenum in the soluble bismuth source and soluble molybdate is 2:

1. The soluble bismuth source is Bi(NO3)3·5H2O, and the soluble molybdate is Na2MoO4·2H2O.

7. The method for preparing the double Z-type heterojunction photocatalytic composite material according to claim 2, characterized in that, The molar ratio of Bi2MoO6 to NH2-UiO-66 is 2:0.05 to 0.06, the solvothermal reaction temperature is 150℃ to 170℃, and the reaction time is 10h to 14h.

8. The application of the double Z-type heterojunction photocatalytic composite material according to claim 1 in the photocatalytic degradation of organic pollutants in wastewater.

9. The application according to claim 8, characterized in that, The organic pollutants are antibiotics.

10. The application according to claim 8, characterized in that, The concentration of organic pollutants in the wastewater is 10 mg / L to 50 mg / L, the dosage of the double Z-type heterojunction photocatalytic composite material is 0.8 g / L, and the pH for photocatalytic degradation is 5 to 11.

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