An AgVO3 / CuBi2O4 photocatalytic material, its preparation method and application

Abstract

This invention discloses an AgVO3 / CuBi2O4 photocatalytic material, its preparation method, and its applications, belonging to the field of photocatalytic materials. This photocatalytic material consists of a hierarchical network structure formed by the interweaving of one-dimensional CuBi2O4 microrods and one-dimensional AgVO3 nanorods, exhibiting a loose and porous internal morphology. The preparation method includes: firstly, using bismuth, copper, and alkali sources as raw materials, a hydrothermal reaction is carried out to obtain one-dimensional CuBi2O4 microrods; then, these are added to a solution of silver and vanadium sources, and a secondary hydrothermal reaction is carried out to obtain the target product. This invention achieves effective separation of photogenerated electron-hole pairs by constructing a hierarchical network structure, significantly improving the utilization rate of visible light. The preparation method of this invention is simple, the conditions are mild, and the product has high purity, showing broad application prospects in the field of organic dye wastewater treatment.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic materials technology, and more specifically, to an AgVO3 / CuBi2O4 photocatalytic material, its preparation method, and its application. Background Technology

[0002] With the rapid development of modern industries such as dyeing, textiles, and printing, large amounts of wastewater containing organic dyes are discharged into the environment. This type of dye wastewater typically exhibits high color intensity, stable chemical properties, and strong biological toxicity, disrupting the ecological balance of aquatic bodies. Therefore, how to efficiently and economically treat organic dye wastewater has become a critical issue urgently needing to be addressed in the field of environmental science.

[0003] Traditional water treatment methods, such as physical adsorption, chemical oxidation, and biological treatment, all have significant shortcomings in treating recalcitrant organic wastewater. Physical adsorption only transfers pollutants from one phase to another, failing to achieve complete degradation and easily leading to secondary pollution in subsequent treatments. Chemical oxidation typically requires the addition of large amounts of chemical reagents, resulting in high operating costs and the potential introduction of new pollutants. Biological treatment has low efficiency in degrading poorly biodegradable dye molecules and has a long treatment cycle. Therefore, developing a novel, efficient, thorough, and environmentally friendly wastewater treatment technology is of significant practical importance.

[0004] Photocatalytic oxidation technology is an advanced oxidation technology that has emerged in recent years. Its basic principle is to use sunlight to excite semiconductor photocatalytic materials, generating highly oxidizing reactive species (such as hydroxyl radicals and superoxide radicals). These reactive species can non-selectively mineralize organic pollutants into carbon dioxide and water. This technology has significant advantages such as mild reaction conditions, no secondary pollution, simple operation, and low operating costs, and is considered one of the ideal ways to solve environmental pollution problems.

[0005] Since Fujishima and Honda discovered in 1972 that TiO2 electrodes could split water under ultraviolet light, photocatalysis technology has been extensively studied. However, traditional photocatalytic materials (such as TiO2) have a wide band gap (approximately 3.2 eV), and can only respond to ultraviolet light, which accounts for less than 5% of the solar spectrum, resulting in extremely low utilization of solar energy. Furthermore, after photoexcitation, the photogenerated electrons and holes generated within single-component photocatalytic materials readily recombine, leading to a significant reduction in the number of effective charge carriers participating in the catalytic reaction. This is the core bottleneck limiting the improvement of photocatalytic efficiency.

[0006] To overcome these shortcomings, researchers have developed various modification strategies, including elemental doping, noble metal deposition, and semiconductor composites. Among these, constructing heterojunction structures is considered one of the most effective methods to suppress photogenerated carrier recombination. By compositing two semiconductor materials with matched band structures, a built-in electric field can be formed at their interface. This field effectively drives photogenerated electrons and holes to migrate in opposite directions, thereby achieving spatial separation and significantly enhancing photocatalytic activity. Furthermore, one-dimensional nanomaterials (such as nanorods and nanowires), due to their unique aspect ratio structure, can provide efficient charge transport channels and increase specific surface area, making them a research hotspot in the field of photocatalysis.

[0007] Silver metavanadate (AgVO3) is a novel silver-based visible-light-responsive photocatalyst with a band gap of approximately 2.1 eV. Its valence band is composed of Ag 4d and O 2p orbitals, while its conduction band consists of Ag 5s and V 3d orbitals. This unique electronic structure gives it excellent absorption of visible light. However, pure silver metavanadate is prone to photocorrosion during photocatalytic reactions, leading to decreased stability. Furthermore, its high recombination rate of photogenerated carriers limits its practical applications. Copper bismuthate (CuBi2O4), a typical p-type semiconductor with a spinel structure and a band gap of approximately 1.5 eV, exhibits even stronger absorption of visible light. It also possesses good chemical stability and is non-toxic, making it a highly promising photocatalyst.

[0008] Currently, there are no reports on the construction of one-dimensional photocatalytic materials by combining AgVO3 and CuBi2O4. Therefore, how to utilize the band matching of the two materials and the synergistic effect of one-dimensional materials to develop a photocatalytic material with high visible light utilization, high carrier separation efficiency, and strong photocatalytic activity is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of existing photocatalytic materials, such as low visible light utilization, easy recombination of photogenerated electron-hole pairs, and limited catalytic activity, and to provide an AgVO3 / CuBi2O4 photocatalytic material, its preparation method, and its application.

[0010] To achieve the above objectives, the specific solution adopted by the present invention is as follows: A method for preparing an AgVO3 / CuBi2O4 photocatalytic material includes the following steps: the photocatalytic material is formed by interweaving one-dimensional CuBi2O4 microrods and one-dimensional AgVO3 nanorods to form a hierarchical network structure with a loose and porous internal morphology. The preparation method of the photocatalytic material includes the following steps: Step (1): Dissolve the bismuth source, copper source and alkali source in deionized water, stir and transfer to a high-pressure reactor, and hydrothermally react at 180°C for 24 hours. The product is washed and dried to obtain a one-dimensional CuBi2O4 micro rod. Step (2): Dissolve the silver source and vanadium source in water, add the one-dimensional CuBi2O4 microrods prepared in step (1), disperse by ultrasonication, transfer to a high-pressure reactor, and hydrothermally react at 180°C for 24 hours. After washing and drying, the product is obtained as an AgVO3 / CuBi2O4 photocatalytic material with one-dimensional AgVO3 nanorods and one-dimensional CuBi2O4 microrods interwoven. In step (2), the amount of the one-dimensional CuBi2O4 microrod added is such that its mass fraction in the AgVO3 / CuBi2O4 photocatalytic material is 10%~30%.

[0011] In the technical solution of this invention, the prepared AgVO3 / CuBi2O4 photocatalytic material possesses a unique one-dimensional / one-dimensional hierarchical network structure. Specifically, one-dimensional AgVO3 nanorods and one-dimensional CuBi2O4 microrods interweave and overlap in space, forming a porous network supported by nanoscale line-to-line contact points. This loose internal structure, rich in open gaps and mesoporous channels, effectively reduces steric hindrance, thereby exposing a large number of active interface sites and facilitating the diffusion and transport of reactant molecules within the photocatalytic material, laying a structural foundation for improving photocatalytic efficiency.

[0012] Preferably, in step (1), the bismuth source is Bi(NO3)3·5H2O, the copper source is Cu(NO3)2·3H2O, and the alkali source is NaOH.

[0013] Preferably, in step (2), the silver source is AgNO3 and the vanadium source is NH4VO3.

[0014] Preferably, the one-dimensional CuBi2O4 microrod has a diameter of 200-400 nm and a length of 1-5 μm; the one-dimensional AgVO3 nanorod has a width of 130-240 nm.

[0015] Preferably, in step (2), the mass fraction of one-dimensional CuBi2O4 microrods in the AgVO3 / CuBi2O4 photocatalytic material is 20%.

[0016] Preferably, in steps (1) and (2), the washing process involves washing the product three times each with deionized water and anhydrous ethanol. This process effectively removes residual ions and organic impurities from the product surface, ensuring the purity of the product.

[0017] Preferably, in steps (1) and (2), the drying process involves vacuum drying at 60°C for 24 hours. Vacuum drying can effectively remove moisture from the product at a lower temperature, preventing the agglomeration of nanoparticles, while avoiding phase changes that may be caused by high temperatures.

[0018] Preferably, in step (2), the ultrasonic dispersion time is 30 minutes. Ultrasonic treatment can uniformly disperse one-dimensional CuBi2O4 microrods in the precursor solutions of silver and vanadium sources, providing the necessary conditions for the subsequent uniform growth of one-dimensional AgVO3 nanorods on their surface.

[0019] The present invention also provides an AgVO3 / CuBi2O4 photocatalytic material, which is prepared by any of the preparation methods described above.

[0020] The present invention also provides the application of the above-mentioned AgVO3 / CuBi2O4 photocatalytic material in the treatment of organic dye wastewater.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The AgVO3 / CuBi2O4 photocatalytic material prepared by the present invention via a two-step hydrothermal method has a hierarchical porous network structure formed by the interlacing of one-dimensional CuBi2O4 microrods and one-dimensional AgVO3 nanorods. This structure is supported by nanoscale line-to-line contact points and is rich in open gaps and mesoporous channels. This loose internal structure greatly increases the specific surface area of ​​the photocatalytic material and exposes more active sites, thereby significantly enhancing the adsorption of reactants and the efficiency of photocatalytic reaction.

[0022] (2) This invention successfully constructed a heterojunction between AgVO3 and CuBi2O4. Due to the matching band structures of the two semiconductor materials, a built-in electric field can be formed at their interface. This built-in electric field can promote the effective separation of photogenerated electrons and holes, thereby significantly suppressing the recombination of photogenerated electron-hole pairs and thus improving photocatalytic efficiency.

[0023] (3) The AgVO3 / CuBi2O4 photocatalytic material prepared in this invention exhibits excellent degradation ability of the azo dye Lanneris Red 5B (LR5B) under simulated sunlight irradiation. Experimental data show that within 150 minutes, the degradation rate of LR5B by this photocatalytic material is as high as 97%, which is 1.35 times and 1.17 times that of pure phase CuBi2O4 (72% degradation rate) and pure phase AgVO3 (83% degradation rate), respectively, fully demonstrating the significant advantages of the technical solution of this invention in improving photocatalytic performance.

[0024] (4) The present invention is prepared by a two-step hydrothermal method. The entire process involves only simple steps of ingredient preparation, mixing, hydrothermal reaction and post-processing. It does not require complex and expensive equipment. The reaction conditions are mild, the operation is convenient, the product has high purity, and it is easy to achieve large-scale production. It has good economic benefits and application prospects. Attached Figure Description

[0025] Figure 1 The XRD patterns are those of the photocatalytic materials prepared in Example 2 and Comparative Examples 1-2 of this invention.

[0026] Figure 2 The images show the SEM spectra of the photocatalytic materials prepared in Comparative Examples 1, 2, and 2 of this invention; wherein, Figure 2 (a) is the SEM image of the pure phase CuBi2O4 in Comparative Example 1. Figure 2 (b) is the SEM image of pure phase AgVO3 in Comparative Example 2. Figure 2 (c) is a SEM image of the CA-20 photocatalytic material prepared in Example 2.

[0027] Figure 3 This is an EDS-mapping image of the photocatalytic material prepared in Example 2 of the present invention; wherein, Figure 3 (a) is a SEM image of the CA-20 photocatalyst material prepared in Example 2. Figure 3 (b) is a surface distribution diagram of Ag (silver) element. Figure 3 (c) is the surface distribution diagram of V (vanadium). Figure 3 (d) is a surface distribution diagram of O (oxygen) element. Figure 3 (e) is the surface distribution diagram of Bi (bismuth). Figure 3 (f) is the surface distribution diagram of Cu (copper). Figure 3 (g) is the EDS energy spectrum.

[0028] Figure 4 The images show the degradation effect of the photocatalytic materials prepared in the various embodiments and comparative examples of this invention on Lanazon Red 5B.

[0029] Figure 5 This is the absorption spectrum of the photocatalytic material prepared in Example 2 of the present invention, showing the concentration of LR5B degraded under simulated sunlight over time; wherein, Figure 5 (a) shows the absorption spectra of the pure-phase CuBi2O4 photocatalyst material in Comparative Example 1 under different irradiation times. Figure 5 (b) shows the absorption spectra of the pure-phase AgVO3 photocatalyst material in Comparative Example 2 under different illumination times. Figure 5 (c) shows the absorption spectra of the CA-20 photocatalytic material prepared in Example 2 under different light exposure times.

[0030] Figure 6The graphs show the degradation effects of the photocatalytic material prepared in Example 2 of this invention on LR5B under different initial concentrations and different ion interferences; wherein, Figure 6 (a) shows the degradation curves at different initial concentrations. Figure 6 (b) shows the degradation curves under different inorganic ion interferences.

[0031] Figure 7 This is an experimental spectrum of free radical capture of the photocatalytic material prepared in Example 2 of the present invention. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0033] This invention provides an AgVO3 / CuBi2O4 photocatalytic material, its preparation method, and its application. The prepared photocatalytic material consists of a hierarchical network structure formed by the interweaving of one-dimensional CuBi2O4 microrods and one-dimensional AgVO3 nanorods, exhibiting a loose and porous morphology. The formation of this unique structure depends on the following two key hydrothermal reaction steps.

[0034] Specifically, the first step of this invention is to prepare one-dimensional CuBi₂O₄ microrods. In this step, a bismuth source (such as Bi(NO₃)₃·5H₂O), a copper source (such as Cu(NO₃)₂·3H₂O), and an alkali source (such as NaOH) are dissolved in deionized water in a specific ratio. The addition of the alkali source is used to adjust the pH value of the solution and provide an alkaline environment for the formation of CuBi₂O₄ crystal nuclei. After thorough stirring to ensure uniform mixing of the reactants, the mixed solution is transferred to a high-pressure reactor. A hydrothermal reaction is carried out under high temperature and high pressure conditions of 180°C for 24 hours. During this process, the reactants undergo a chemical reaction in a closed system, and through a "dissolution-crystallization" mechanism, anisotropically grow into one-dimensional microrod-like structures. The hydrothermal method can effectively control the morphology, size, and crystallinity of the product. After the reaction, the product is washed three times each with deionized water and anhydrous ethanol to thoroughly remove ions (such as NaOH) adsorbed on the surface of the product. + NO3 - After removing organic impurities, the sample was vacuum dried at 60°C for 24 hours to obtain a pure one-dimensional CuBi2O4 microrod.

[0035] The second step of this invention involves synthesizing one-dimensional AgVO3 nanorods in the presence of the aforementioned one-dimensional CuBi₂O₄ microrods, thereby obtaining a photocatalytic material. Specifically, a silver source (e.g., AgNO₃) and a vanadium source (e.g., NH₄VO₃) are dissolved in water to form a homogeneous precursor solution. Then, a measured amount of one-dimensional CuBi₂O₄ microrods is added (the amount added should be controlled so that the mass fraction of CuBi₂O₄ in the final product is 10%–30%, preferably 20%). The microrods are ultrasonically dispersed for 30 minutes to ensure uniform dispersion of the CuBi₂O₄ microrods in the AgVO₃ precursor solution, providing uniform nucleation sites for subsequent growth. Subsequently, this mixture is transferred again to a high-pressure reactor and subjected to a second hydrothermal reaction at 180°C for 24 hours. Under these conditions, AgVO₃ crystals nucleate and tend to grow into one-dimensional nanorod structures. Because of the pre-prepared CuBi₂O₄ microrods in the system, the newly generated AgVO₃ nanorods grow around and interweave with the CuBi₂O₄ microrods. During growth, the two intertwine and overlap, eventually spontaneously assembling into a hierarchical network structure. Within this structure, due to the random stacking and cross-support of the rod-like structures, numerous open gaps and mesoporous channels naturally form, exhibiting a loose and porous morphology. After the reaction, the material was washed three times each with deionized water and anhydrous ethanol, and then vacuum-dried at 60°C for 24 hours to obtain a pure AgVO₃ / CuBi₂O₄ photocatalyst.

[0036] The AgVO3 / CuBi2O4 photocatalytic material prepared in this invention can be used to treat organic dye wastewater, and is especially suitable for degrading azo dyes represented by Lanazon Red 5B.

[0037] The technical solution and its effects of the present invention will be described in detail below through specific embodiments and comparative examples.

[0038] Example 1 (Preparation of CA-10 photocatalytic material) This embodiment provides a CuBi₂O₄ photocatalytic material with a CuVO₃ / CuBi₂O₄ mass fraction of 10%, and its preparation method is as follows: Step (1) Preparation of one-dimensional CuBi2O4 microrods: Weigh 2.42g of Bi(NO3)3·5H2O, 0.6g of Cu(NO3)2·3H2O and 0.87g of NaOH, add them to 60ml of deionized water and stir thoroughly for 3 hours; then transfer the mixture to a 100ml polytetrafluoroethylene-lined high-pressure reactor, place it in an oven and heat it to 180℃ and keep it at a constant temperature for 24 hours; after the reaction is completed, wash the obtained sample with deionized water and anhydrous ethanol in sequence and centrifuge it three times, put it in a vacuum drying oven and dry it at 60℃ for 24 hours to obtain one-dimensional CuBi2O4 microrods; Step (2) Preparation of CA-10 photocatalytic material: Dissolve 0.212g of AgNO3 and 0.146g of NH4VO3 in 60ml of water, then add 0.029g of one-dimensional CuBi2O4 microrods prepared in step (1) and ultrasonically disperse for 30 minutes; transfer the mixture to a polytetrafluoroethylene-lined high-pressure reactor and react at 180℃ for 24 hours; after the reaction, wash the obtained sample three times with deionized water and three times with anhydrous ethanol, and vacuum dry at 60℃ for 24 hours to obtain AgVO3 / CuBi2O4 photocatalytic material with one-dimensional AgVO3 nanorods and one-dimensional CuBi2O4 microrods intertwined, wherein the mass fraction of CuBi2O4 is 10%, denoted as CA-10.

[0039] Example 2 (Preparation of CA-20 photocatalytic material) This embodiment provides an AgVO3 / CuBi2O4 photocatalytic material with a CuBi2O4 mass fraction of 20%. The preparation method is basically the same as in Example 1, except that the amount of one-dimensional CuBi2O4 microrods added in step (2) is 0.058 g. Finally, an AgVO3 / CuBi2O4 photocatalytic material with interwoven one-dimensional AgVO3 nanorods and one-dimensional CuBi2O4 microrods is obtained, wherein the mass fraction of CuBi2O4 is 20%, denoted as CA-20.

[0040] Example 3 (Preparation of CA-30 photocatalytic material) This embodiment provides an AgVO3 / CuBi2O4 photocatalytic material with a CuBi2O4 mass fraction of 30%. The preparation method is basically the same as in Example 1, except that the amount of one-dimensional CuBi2O4 microrods added in step (2) is 0.087 g. Finally, an AgVO3 / CuBi2O4 photocatalytic material with interwoven one-dimensional AgVO3 nanorods and one-dimensional CuBi2O4 microrods is obtained, wherein the mass fraction of CuBi2O4 is 30%, denoted as CA-30.

[0041] Comparative Example 1 (Preparation of pure-phase CuBi2O4 photocatalytic material) This comparative example provides a pure phase CuBi2O4 photocatalytic material, whose preparation method is exactly the same as step (1) of Example 1, only obtaining one-dimensional CuBi2O4 micro rods, without performing subsequent composite steps.

[0042] Comparative Example 2 (Preparation of pure-phase AgVO3 photocatalytic material) This comparative example provides a pure-phase AgVO3 photocatalytic material, the preparation method of which is basically the same as step (2) of Example 1, the difference being that: no CuBi2O4 microrods are added, only 0.212g of AgNO3 and 0.146g of NH4VO3 are dissolved in water, and after sonication, hydrothermal reaction, washing and drying, pure-phase one-dimensional AgVO3 nanomaterials are obtained.

[0043] Performance characterization and photocatalytic testing The photocatalytic materials prepared in the above embodiments and comparative examples were systematically characterized in terms of phase structure, microstructure, and photocatalytic performance. The specific test results are analyzed as follows: (1) Phase structure analysis The crystal structure of the sample was analyzed using X-ray diffraction (XRD). Detailed test results can be found in [link to XRD section]. Figure 1 .from Figure 1 It can be seen that the diffraction peak positions of pure-phase AgVO3 are completely consistent with the standard card (JCPDS No. 29-11541) of monoclinic β-AgVO3, especially the characteristic peaks of the (501) and (-112) crystal planes are very obvious. The diffraction peaks of pure-phase CuBi2O4 correspond to JCPDS No. 48-1886. In the CA-20 photocatalytic material prepared in Example 2, the characteristic diffraction peaks of both AgVO3 and CuBi2O4 can be clearly observed simultaneously, and no other impurity peaks are detected. This indicates that the present invention has successfully prepared a high-purity, impurity-free AgVO3 / CuBi2O4 photocatalytic material.

[0044] (2) Microscopic morphology analysis The surface morphology of the samples was observed using field emission scanning electron microscopy (SEM). Detailed test results can be found in [link to relevant documentation]. Figure 2 . Figure 2 (a) shows that the pure phase CuBi2O4 exhibits a uniform one-dimensional micron rod-like structure with a diameter of about 200-400 nm and a length of about 1-5 µm. Figure 2 (b) shows that pure phase AgVO3 exhibits a one-dimensional nanorod structure with a smooth surface and a width between 130 and 240 nm. Figure 2(c) is a SEM image of the CA-20 photocatalytic material prepared in Example 2. The image clearly shows that one-dimensional micron-sized CuBi₂O₄ rods and one-dimensional nanon-sized AgVO₃ rods intertwine to form a micro-nano multi-scale hierarchical network structure. This structure has a loose internal structure with numerous pores and open gaps supported by line-to-line contact points. It is important to note that although CuBi₂O₄ is generally micron-shaped and AgVO₃ is nanon-shaped, they form a close nanoscale contact at the interface, and the pore walls and gaps of the overall network structure are in the nano / submicron range. Therefore, this composite material still belongs to a hierarchical nanostructure material. This unique hierarchical network structure helps increase the specific surface area of ​​the material, exposing more active sites, thereby improving photocatalytic activity.

[0045] (3) Elemental distribution analysis Figure 3 The image shows the EDS-mapping diagram of the CA-20 photocatalyst material prepared in Example 2. Figure 3 The red box in (a) indicates the selected test site. Figure 3 (b) to Figure 3 (g) shows that the five elements Cu, Bi, O, V and Ag are uniformly distributed on the surface of the photocatalytic material. This directly confirms that CA-20 is a complex of CuBi2O4 and AgVO3, and that the two phases are uniformly distributed, which is consistent with the XRD test results.

[0046] (4) Photocatalytic degradation performance analysis The photocatalytic performance of each sample was evaluated under simulated sunlight irradiation using the azo dye Lanners Red 5B (LR5B) as the target pollutant. Figure 4 The graphs show the degradation kinetics of the target pollutant by pure CuBi2O4, pure AgVO3, and AgVO3 / CuBi2O4 photocatalysts with different composite ratios (CA-10, CA-20, CA-30). The vertical axis represents the relative concentration C / C. o The horizontal axis represents the illumination time, which includes two processes: the dark reaction (the stage when the lights are off, -20 to 0 min) and the light reaction (the stage when the lights are on, 0 to 150 min).

[0047] Blank control group: Under conditions without photocatalytic material, the concentration of the target pollutant hardly changed over time, and the C / C ratio was [value missing] at 150 min. o The value remained at approximately 0.95, indicating that the photolysis of the pollutants themselves under simulated sunlight was negligible, and the degradation process was dominated by photocatalytic materials.

[0048] Comparison of single-component photocatalytic materials: The pure CuBi2O4 sample showed weak adsorption in the dark reaction stage, and the degradation rate gradually decreased over time after the light was turned on. At 150 min, the C / C ratio was [missing value]. oThe C / C ratio of the pure AgVO3 sample was approximately 0.28, with a degradation rate of about 72%. o The concentration is approximately 0.17, and the degradation rate is approximately 83%. Both exhibit significant carrier recombination issues, which limit their catalytic activity.

[0049] Comparison of different compound ratios: C / C ratio of CA-10 at 150 min o The concentration of C-30 was approximately 0.25, with a degradation rate of about 75%, slightly better than pure CuBi₂O₄ but lower than pure AgVO₃, indicating that the low-proportion composite did not form an effective synergistic effect; the C / C ratio of CA-30 at 150 min was approximately 0.25. o The degradation rate was approximately 79%, close to that of pure AgVO3. Excess CuBi2O4 may have masked the active sites of AgVO3. CA-20 exhibited significant performance advantages, with a degradation rate much higher than other samples, and a C / C ratio of approximately 0.21 at 150 min. o The degradation rate was approximately 97%, which is 1.35 times that of pure CuBi₂O₄ and 1.17 times that of pure AgVO₃. This result indicates that a 20% CuBi₂O₄ composite ratio can maximize the interfacial charge separation effect of the AgVO₃ / CuBi₂O₄ photocatalytic material, effectively suppress photogenerated carrier recombination, and significantly improve the photocatalytic degradation efficiency.

[0050] (5) Spectral change analysis during degradation process Figure 5 The UV-Vis absorption spectra of Lanazol Red 5B (LR5B) solutions during the degradation of pure CuBi2O4, pure AgVO3, and the optimal sample CA-20 are shown as curves of change with illumination time. The horizontal axis represents wavelength (200~800nm), and the vertical axis represents absorbance. The characteristic absorption peaks of Lanazol Red 5B (LR5B) are mainly located at 520-530nm (visible region, chromophore) and 200-300nm (UV region, benzene ring structure).

[0051] Pure CuBi2O4: from Figure 5 (a) It can be seen that the intensity of the characteristic absorption peak decreases slowly with the extension of the illumination time. At 150 min, the characteristic peak in the visible light region still has obvious residue, indicating that it can only partially destroy the chromophore of Lanners Red 5B (LR5B) and the degradation is incomplete.

[0052] Pure AgVO3: by Figure 5 (b) It can be seen that the absorption peak intensity decreases faster than that of CuBi2O4, but there is still a weak characteristic absorption in the visible light region at 150 min, and the absorption peak in the ultraviolet region has not completely disappeared, indicating that the intermediate product of Lanners Red 5B (LR5B) has not been completely degraded.

[0053] CA-20: by Figure 5(c) It can be seen that with the extension of illumination time, the intensity of the characteristic absorption peak in the visible light region shows a continuous and rapid decreasing trend, and the characteristic peak almost disappears completely at 150 min. At the same time, the absorption peak in the ultraviolet region also decreases significantly and no new impurity peaks are generated. This phenomenon proves that CA-20 can efficiently destroy the chromophore of Lanazol Red 5B (LR5B), enabling its effective degradation, rather than just achieving decolorization through adsorption, further verifying its excellent photocatalytic oxidation ability.

[0054] (6) Actual wastewater adaptability test Figure 6 The degradation kinetics curves of the optimal sample CA-20 on Lanasole Red 5B (LR5B) under different initial concentrations and different inorganic ion interference conditions were obtained to simulate the complex environment of actual dyeing and printing wastewater and evaluate its application adaptability.

[0055] (6-1) Degradation performance at different initial concentrations The initial concentrations of Lanazon Red 5B (LR5B) were set at 20, 40, 60, and 80 mg / L, and the degradation efficiency of CA-20 was tested. Figure 6 (a) It can be seen that the degradation rate is the fastest under the low concentration condition of 20 mg / L, and the C / C ratio is highest at 120 min. o It has been reduced to below 0.1, and almost completely degraded after 150 min; under 40 mg / L conditions (standard test concentration), the C / C ratio at 150 min is... o ≈0.03, degradation rate approximately 97%; under 60 mg / L conditions, C / C ratio at 150 min. o ≈0.16, degradation rate approximately 84%; under high concentration conditions of 80 mg / L, C / C ratio at 150 min. o The concentration was approximately 0.41, with a degradation rate of about 59%. The reasons for this are: high concentrations of Lanazol Red 5B (LR5B) consume more active free radicals, and the light scattering / absorption effect of high-concentration solutions reduces the utilization rate of visible light by the photocatalyst, leading to a decrease in degradation efficiency. However, even at a high concentration of 80 mg / L, CA-20 still maintains high degradation activity, indicating its good adaptability to treating medium-to-low concentrations of Lanazol Red 5B (LR5B) in dyeing and printing wastewater.

[0056] (6-2) Inorganic ion interference tolerance Select common inorganic ions (Cu) in actual dyeing and printing wastewater 2+ HPO4 2- Cl - The effect of CA-20 on the degradation performance of Lanazon Red 5B (LR5B) was tested (at a concentration of 1 mmol / L), with the group without ion addition serving as a control: Figure 6 (b) It can be seen that Cl -In the interference group, the degradation curve almost overlapped with that of the control group, and the degradation rate at 150 min was not significantly different from that of the control group, indicating that CA-20 inhibits the degradation of Cl. - It has extremely high tolerance and can be adapted to compounds containing high concentrations of Cl. - The scene of dyeing and printing wastewater treatment; Cu 2+ In the interference group, the degradation rate decreased slightly, and the C / C ratio was lower at 150 min. o The degradation rate was approximately 0.25, lower than the control group, because Cu... 2+ As an electron scavenger, it reacts with photogenerated electrons on the surface of photocatalytic materials, consuming some active electrons and thus reducing the generation efficiency of active free radicals; HPO4 2- In the interference group, the degradation rate decreased slightly more than that of Cu. 2+ Group, C / C at 150 min o ≈0.18, the degradation rate was reduced by about 12% compared with the control group, HPO4 2- As negatively charged ions, they readily combine with photogenerated holes on the surface of photocatalytic materials, inhibiting hole-involved oxidation reactions and thus reducing degradation efficiency. Overall, CA-20 exhibits good tolerance to common inorganic ions in actual wastewater, only being affected under high-concentration multi-ion complex conditions, indicating its potential application in the treatment of Lanazon Red 5B (LR5B) dyeing and printing wastewater.

[0057] (7) Photocatalytic mechanism analysis To reveal the main active species in the photocatalytic process, free radical capture experiments were conducted. Disodium ethylenediaminetetraacetate (EDTA-2Na, vacancy h) was added to the reaction system. + (Scavenger), p-benzoquinone (BQ, superoxide radical·O2) - (Scavenger) and isopropanol (IPA, hydroxyl radical ·OH scavenger), the results are as follows Figure 7 As shown.

[0058] The results showed that the degradation rate of LR5B decreased slightly to 86.9% after the addition of EDTA-2Na, indicating that h + It participated in the reaction but was not the most dominant reactive species. Upon addition of BQ, the degradation rate significantly decreased to 65.5%, indicating that superoxide radicals (·O2) were involved in the reaction but were not the most active species. - The hydroxyl radical (·OH) plays a crucial role in the reaction. However, after the addition of IPA, the degradation rate dropped sharply to 25.1%, far lower than the degradation rate under normal conditions. This result clearly indicates that hydroxyl radicals (·OH) are the main active species in the photocatalytic degradation process of the AgVO3 / CuBi2O4 photocatalyst material of this invention, while holes (·OH) are the main active species. + ) and superoxide radicals (·O2) - It plays an auxiliary role in degradation.

[0059] In summary, this invention successfully prepared an AgVO3 / CuBi2O4 photocatalytic material formed by the interweaving of one-dimensional CuBi2O4 microrods and one-dimensional AgVO3 nanorods via a two-step hydrothermal method. This photocatalytic material possesses a unique hierarchical network structure with a loose and porous interior, exposing a large number of active sites. XRD and SEM characterization confirmed the high purity and ideal microstructure of the prepared photocatalytic material. Photocatalytic performance testing showed that when the CuBi2O4 mass fraction was 20% (CA-20), the degradation rate of Lanazon Red 5B reached 97% within 150 minutes under simulated sunlight irradiation, which was 1.35 times and 1.17 times that of pure CuBi2O4 and AgVO3, respectively. Spectroscopic analysis proved that CA-20 can effectively degrade pollutants, rather than merely decolorizing them through adsorption. Actual wastewater adaptability testing showed that CA-20 effectively degraded pollutants and common inorganic ions (especially Cl-) at different initial concentrations. - It exhibits good tolerance. Free radical capture experiments confirmed that hydroxyl radicals are the main reactive species. The preparation method of this invention is simple, the conditions are mild, and the product has high purity, showing broad application prospects in the field of organic dye wastewater treatment.

[0060] In summary, this invention provides an AgVO3 / CuBi2O4 photocatalytic material with simple preparation process, low cost, and excellent photocatalytic performance, as well as its preparation method and application. It successfully overcomes the technical bottlenecks of low visible light utilization and high carrier recombination rate of traditional photocatalytic materials, and shows great application potential and market value in the field of organic dye wastewater treatment.

[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can make various improvements and modifications without departing from the spirit and principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an AgVO3 / CuBi2O4 photocatalytic material, characterized in that, The photocatalytic material is a hierarchical network structure formed by the interweaving of one-dimensional CuBi2O4 microrods and one-dimensional AgVO3 nanorods, and has a loose and porous morphology inside. The preparation method includes the following steps: Step (1): Dissolve the bismuth source, copper source and alkali source in deionized water, stir and transfer to a high-pressure reactor, and hydrothermally react at 180°C for 24 hours. The product is washed and dried to obtain a one-dimensional CuBi2O4 micro rod. Step (2): Dissolve the silver source and vanadium source in water, add the one-dimensional CuBi2O4 microrods prepared in step (1), disperse by ultrasonication, transfer to a high-pressure reactor, and hydrothermally react at 180°C for 24 hours. After washing and drying, the product is obtained as an AgVO3 / CuBi2O4 photocatalytic material with one-dimensional AgVO3 nanorods and one-dimensional CuBi2O4 microrods interwoven. In step (2), the amount of the one-dimensional CuBi2O4 microrod added is such that its mass fraction in the AgVO3 / CuBi2O4 photocatalytic material is 10%~30%.

2. The preparation method according to claim 1, characterized in that, In step (1), the bismuth source is Bi(NO3)3·5H2O, the copper source is Cu(NO3)2·3H2O, and the alkali source is NaOH.

3. The preparation method according to claim 1, characterized in that, In step (2), the silver source is AgNO3 and the vanadium source is NH4VO3.

4. The preparation method according to claim 1, characterized in that, The diameter of the one-dimensional CuBi2O4 microrod is 200-400 nm and the length is 1-5 μm; the width of the one-dimensional AgVO3 nanorod is 130-240 nm.

5. The preparation method according to claim 1, characterized in that, In step (2), the mass fraction of one-dimensional CuBi2O4 microrods in the AgVO3 / CuBi2O4 photocatalytic material is 20%.

6. The preparation method according to claim 1, characterized in that, In steps (1) and (2), the specific washing operation is as follows: wash three times each with deionized water and anhydrous ethanol.

7. The preparation method according to claim 1, characterized in that, In steps (1) and (2), the specific drying operation is vacuum drying at 60°C for 24 hours.

8. The preparation method according to claim 1, characterized in that, In step (2), the ultrasonic dispersion time is 30 minutes.

9. An AgVO3 / CuBi2O4 photocatalytic material, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. The application of the AgVO3 / CuBi2O4 photocatalytic material according to claim 9 in the treatment of organic dye wastewater.

Images