A praseodymium-based MOF-enhanced defective TiO2 photoelectrode material, its preparation method, and its application.

Abstract

This invention relates to the field of new energy optoelectronic functional materials technology, specifically to a praseodymium-based MOF-enhanced defective TiO2 photoelectrode material, its preparation method, and its application. The specific technical solution includes the following steps: (1) dissolving a praseodymium-based rare earth metal salt in an aqueous solution to obtain a mixed solution A; (2) dissolving an organic ligand in an organic solvent to obtain a mixed solution B; (3) mixing mixed solutions A and B with magnetic stirring, then placing them into a matrix for a hydrothermal reaction. After the reaction is complete, the praseodymium-based MOF-enhanced defective TiO2 photoelectrode material is obtained. This method effectively improves the problems of narrow photoresponse range, high carrier recombination rate, and insufficient stability of defective TiO2 photoelectrode materials, significantly enhancing their photoelectrocatalytic performance. This invention also overcomes the problems of difficulty in controlling the morphology and size of praseodymium-based MOF materials and poor composite performance with other functional materials in existing preparation processes.

Description

Technical Field

[0001] This invention relates to the field of new energy optoelectronic functional materials technology, specifically to a praseodymium-based MOF-enhanced defective TiO2 photoelectrode material, its preparation method, and its application. Background Technology

[0002] Photoelectrochemical (PEC) technology has attracted widespread attention in recent years due to its ability to synergistically achieve pollutant degradation and energy conversion under solar energy. Compared with traditional physical, chemical, or biological treatment methods, PEC technology can not only efficiently mineralize organic pollutants but also utilize the chemical energy contained in the pollutants to simultaneously generate high-value-added chemicals such as H2 and H2O2, accompanied by electrical energy output. This achieves the integration of pollution control, resource recovery, and energy conversion, demonstrating promising application prospects. As the core component of the PEC system, the photoelectrode material's light absorption capacity, carrier separation and transport efficiency, and interfacial reactivity directly determine the overall photoelectrocatalytic performance.

[0003] In recent years, TiO2-based photoelectrode materials have attracted widespread attention due to their advantages such as low cost, good chemical stability, and environmental friendliness. However, they still suffer from problems such as wide band gap, low visible light utilization, severe recombination of photogenerated carriers, and insufficient long-term stability, which limit their practical application in the field of photoelectrocatalysis. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a praseodymium-based MOF-enhanced defective TiO2 photoelectrode material, its preparation method, and its applications. This method effectively improves the problems of narrow photoresponse range, high carrier recombination rate, and insufficient stability of defective TiO2 photoelectrode materials, significantly enhancing their photoelectrocatalytic performance. This invention also overcomes the difficulties in controlling the morphology and size of praseodymium-based MOF materials and the poor composite performance with other functional materials in existing preparation processes. It has advantages such as simple preparation process, mild reaction conditions, ease of operation, and suitability for large-scale preparation.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing a praseodymium-based MOF-enhanced defective TiO2 photoelectrode material, comprising the following steps: (1) Dissolve praseodymium rare earth metal salt in water to prepare mixed solution A; the rare earth metal salt is one or both of PrNO3·6H2O and CeNO3·6H2O; (2) Dissolve the organic ligand in an organic solvent to prepare a mixed solution B; the concentration of the organic ligand is 0.04-0.09 mol / L; (3) Mix the mixed solution A and mixed solution B by magnetic stirring, then put them into the matrix and carry out a hydrothermal reaction. After the reaction is completed, the praseodymium-based MOF-enhanced defect TiO2 photoelectrode material is obtained; the matrix is ​​defective titanium dioxide nanotubes (Defect-TiO2NTs).

[0006] Preferably, in step (1), when the rare earth metal salt is PrNO3·6H2O, the concentration of PrNO3·6H2O is 0.02-0.04 mol / L.

[0007] Preferably, in step (1), when the rare earth metal salts are PrNO3·6H2O and CeNO3·6H2O, the concentration of PrNO3·6H2O is 0.03-0.05 mol / L and the concentration of CeNO3·6H2O is 0.03-0.05 mol / L.

[0008] Preferably, in step (2), the organic solvent is N,N-dimethylformamide.

[0009] Preferably, in step (2), the organic ligand is terephthalic acid.

[0010] Preferably, in step (3), the temperature of the hydrothermal reaction is 140-160℃ and the time is 24-48h.

[0011] Accordingly, a praseodymium-based MOF-enhanced defective TiO2 photoelectrode material prepared by the aforementioned preparation method is provided.

[0012] Accordingly, the praseodymium-based MOF-enhanced defective TiO2 photoelectrode material prepared by the aforementioned method is applied in the treatment of high-concentration, recalcitrant organic wastewater and in synergistic photoelectrocatalytic hydrogen production.

[0013] The present invention has the following beneficial effects: (1) This invention overcomes the problems of difficult control of morphology and size of traditional praseodymium-based MOF materials and poor composite performance with other functional materials by loading praseodymium-based MOFs onto the surface of defective TiO2 nanotubes. The MOF size is reduced from the traditional 200-300 μm to about 1 μm, and the morphology of praseodymium-based MOF materials changes from the traditional block shape to rod or petal shape. The rod-shaped Pr MOFs and petal-shaped Pr-Ce MOFs formed can be uniformly distributed on the surface of defect-TiO2NTs, and together with the nanotube array, they construct a multi-level structure, further improving the specific surface area and surface roughness of the composite material, significantly increasing the catalytic active sites, thereby enhancing the material's ability to absorb and utilize light.

[0014] (2) The Pr MOFs / Defect-TiO2NTs and Pr-Ce MOFs / Defect-TiO2NTs heterojunction structures constructed in this invention effectively broaden the band structure of the materials, improve the response to visible light, and promote the separation and migration of photogenerated electrons and holes, significantly suppressing carrier recombination. At the same time, the formation of multidimensional heterojunctions further optimizes the interfacial charge transport dynamics, improves the photoelectric conversion efficiency, and thus significantly enhances the photoelectrocatalytic performance and hydrogen evolution reaction activity of the composite photoelectrode.

[0015] (3) The composite photoelectrode materials prepared in this invention exhibit excellent photoelectrocatalytic performance in the treatment of high-concentration, recalcitrant organic wastewater. Specifically, Pr MOFs / Defect-TiO2NTs achieved almost complete degradation of 4-(dimethylamino)benzaldehyde (DMBA) wastewater within 120 min, with a mineralization rate of 82%; Pr-Ce MOFs / Defect-TiO2NTs achieved a mineralization rate of 92% for sulfathiazole (STZ) wastewater. Furthermore, the composite photoelectrode materials possess a low Tafel slope and excellent long-term operational stability, with minimal change in application potential during continuous operation, indicating promising application prospects in synergistic pollutant degradation and photoelectrocatalytic hydrogen production.

[0016] (4) This invention prepares rod-shaped Pr MOFs / Defect-TiO2NTs and petal-shaped Pr-CeMOFs / Defect-TiO2NTs photoelectrode materials. The praseodymium-modified MOF-modified Defect-TiO2NTs photoelectrode material significantly enhances the electrode photocurrent density, approximately 6 times and 11 times that of Defect-TiO2NTs, respectively. The band gap is reduced to 1.9 eV and 1.8 eV, respectively, further broadening the band structure, increasing the absorption of visible light, and promoting the migration and separation of charge carriers. Laboratory simulations of wastewater degradation and simultaneous H2 generation were conducted on the prepared photoelectrode materials. The results show that Pr MOFs / Defect-TiO2NTs and Pr-Ce MOFs / Defect-TiO2NTs photoelectrode materials have significant advantages over other photoelectrode materials in photoelectrocatalytic degradation of organic wastewater, exhibiting excellent degradation efficiency and mineralization ability, and good repeatability and stability. Meanwhile, the hydrogen production performance of the composite electrode showed that the experimental results were superior to those of the original Defect-TiO2NTs. Attached Figure Description

[0017] Figure 1(a)-(b) are SEM images of the Pr MOFs / Defect-TiO2NTs photoelectrode materials prepared in Example 1 and the Pr-Ce MOFs / Defect-TiO2NTs photoelectrode materials prepared in Example 2, respectively. Figure 2 (a)-(b) show the photocurrent response of the Pr MOFs / Defect-TiO2NTs prepared in Example 1 and the Pr-Ce MOFs / Defect-TiO2NTs prepared in Example 2, respectively. Figure 3 (a)-(b) show the impedance response of the Pr MOFs / Defect-TiO2NTs prepared in Example 1 and the Pr-Ce MOFs / Defect-TiO2NTs prepared in Example 2, respectively. Figure 4 (a)-(c) are BET comparison diagrams of the photoelectrode materials of Defect-TiO2NTs, Pr MOFs / Defect-TiO2NTs prepared in Example 1, and Pr-Ce MOFs / Defect-TiO2NTs prepared in Example 2, respectively. Figure 5 (a)-(b) are the UV-Vis DRS spectra of Defect-TiO2NTs and Pr MOFs / Defect-TiO2NTs and Pr-Ce MOFs / Defect-TiO2NTs photoelectrode materials prepared in Examples 1 and 2, respectively. Detailed Implementation

[0018] 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 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 scope of protection of the present invention.

[0019] Unless otherwise specified, the technical means used in the implementation examples are conventional means well known to those skilled in the art.

[0020] This invention breaks through the traditional single modification strategy for defective TiO2 photoelectrode materials, combining for the first time the advantages of praseodymium-based MOFs (PrMOFs) in high specific surface area, tunable structure, and abundant active sites with the excellent one-dimensional electron transport characteristics of Defect-TiO2NTs. By in-situ growing rod-shaped Pr MOFs and petal-shaped Pr-Ce MOFs on the surface of Defect-TiO2NTs, a multidimensional heterojunction composite structure is constructed. This not only effectively broadens the material's band structure and visible light response range but also promotes the rapid separation and migration of photogenerated electrons and holes, significantly suppresses carrier recombination, and improves light energy utilization efficiency and photoelectric conversion performance. Simultaneously, the unique porous structure and nanomorphic morphology of MOFs further increase the specific surface area and surface roughness of the composite electrode, providing more catalytic active sites and additional charge transport channels, thereby significantly enhancing the photoelectrocatalytic activity and hydrogen evolution reaction kinetics of the composite photoelectrode.

[0021] This invention provides a method for preparing a praseodymium-based MOF-enhanced defective TiO2 photoelectrode material, solving the problems of low visible light utilization, severe carrier recombination, poor conductivity, and insufficient stability inherent in traditional TiO2 photoelectrodes. Furthermore, addressing the shortcomings of existing MOF material preparation processes, such as difficulty in controlling morphology and size, poor matrix recombination, complex processes, and high energy consumption, this invention employs a simple one-step solvothermal method to in-situ load praseodymium-based MOFs onto the surface of Defect-TiO2NTs. This method offers advantages such as simple process, mild reaction conditions, ease of operation, and suitability for large-scale preparation. The prepared composite material exhibits broad-spectrum absorption, efficient carrier separation capability, low interfacial resistance, and excellent cycling stability, enabling efficient degradation of high-concentration, recalcitrant organic wastewater and synergistic photoelectrocatalytic hydrogen production. This invention not only provides a new technical path for PEC technology to move from laboratory research to practical engineering applications, but also realizes the synergistic coupling of high-value utilization of rare earth resources and energy recovery from wastewater resources. It is of great significance for promoting the implementation of the "dual carbon" target, improving the efficiency of clean energy utilization and ensuring ecological and environmental safety. At the same time, it demonstrates good scientific research value and broad socio-economic application prospects.

[0022] The Pr MOFs / Defect-TiO2NTs and Pr-Ce MOFs / Defect-TiO2NTs photoelectrode materials prepared in this invention exhibit excellent performance in photoelectrocatalytic degradation and energy recovery. Specifically, Pr MOFs / Defect-TiO2NTs achieved almost complete degradation of DMBA wastewater within 120 min in the degradation experiment, with a mineralization rate of 82%; Pr-Ce MOFs / Defect-TiO2NTs achieved a mineralization rate of 92% for STZ simulated wastewater. Furthermore, the photoelectrode materials exhibited a lower Tafel slope and excellent long-term stability in the hydrogen evolution reaction, indicating faster HER reaction kinetics and higher catalytic activity. This invention achieves synergistic coupling of pollutant degradation and clean energy recovery, which is of great significance for promoting the engineering application of photoelectrocatalysis technology in environmental governance and new energy conversion.

[0023] The specific scheme is as follows: A method for preparing a praseodymium-based MOF-enhanced defective TiO2 photoelectrode material, comprising the following steps: (1) Dissolve praseodymium rare earth metal salt in water to prepare mixed solution A; the rare earth metal salt is one or both of PrNO3·6H2O and CeNO3·6H2O; Wherein, when the rare earth metal salt is PrNO3·6H2O, the concentration of PrNO3·6H2O is 0.02-0.04 mol / L.

[0024] Furthermore, when the rare earth metal salts are PrNO3·6H2O and CeNO3·6H2O, the concentration of PrNO3·6H2O is 0.03-0.05 mol / L, and the concentration of CeNO3·6H2O is 0.03-0.05 mol / L.

[0025] (2) Terephthalic acid (H2BDC) is dissolved in N,N-dimethylformamide (DMF) to prepare mixed solution B; the concentration of terephthalic acid is 0.04-0.09 mol / L; (3) Place mixed solution A and mixed solution B on a magnetic stirrer and stir magnetically at a speed of 800 rpm. Add mixed solution A to mixed solution B to obtain mixed solution C. Add hexadecyltrimethylammonium bromide (CTAB) (0.001-0.002 mol / L) or hexadecyltrimethylammonium bromide (CTAB) and ammonia to mixed solution C to adjust the morphology. CTAB is a cationic surfactant that mainly controls the morphology by forming micelles and self-assemblies in the synthesis. Ammonia mainly affects the nucleation and growth process of crystals by adjusting the pH value and deprotonation rate of the solution.

[0026] (4) Place the matrix (Defect-TiO2NTs) into the mixed solution C and carry out a hydrothermal reaction. The hydrothermal reaction temperature is 140-160℃ and the time is 24-48h. After the reaction is completed, the praseodymium-based MOF-enhanced defect TiO2 photoelectrode material is obtained. Thus, Pr MOFs / Defect-TiO2NTs and Pr-Ce MOFs / Defect-TiO2NTs photoelectrode materials are obtained.

[0027] This invention provides a praseodymium-based MOF-enhanced defect TiO2 photoelectrode material prepared by the above preparation method, namely Pr MOFs / Defect-TiO2NTs and Pr-Ce MOFs / Defect-TiO2NTs photoelectrode materials.

[0028] The present invention also provides that the above-mentioned material can realize the resource-based treatment of high-concentration recalcitrant organic wastewater, through efficient degradation of pollutants at the anode and synergistic hydrogen evolution reaction at the cathode, thereby achieving the coupled utilization of pollution control and clean energy recovery.

[0029] The present invention will be described in detail below with reference to specific embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0030] Example 1 A method for preparing a praseodymium-based MOF-enhanced defective TiO2 photoelectrode material includes the following steps: (1) Solution A was prepared by dissolving 0.4 mmol Pr(NO3)3·6H2O in 2 mL of deionized water, and solution B was prepared by dissolving 0.6 mmol terephthalic acid (H2BDC) in 10 mL of DMF. Solution A and solution B were mixed to prepare mixed solution C, and 0.00787 g of hexadecyltrimethylammonium bromide (CTAB) was added to mixed solution C. The mixture was stirred at room temperature for 1 h to form a uniform and transparent solution at a stirring speed of 800 rpm.

[0031] (2) The prepared mixed solution was transferred to a polytetrafluoroethylene high-pressure reactor, and then the dried Defect-TiO2NTs sheet was placed in the high-pressure reactor and sealed; and transferred to an oven with programmed temperature control, heated to 160 °C at a heating rate of 2 °C / min, reacted for 48 h, and then cooled to room temperature.

[0032] (3) After the reaction is complete, the reaction vessel is naturally cooled to room temperature. The Pr MOFs / Defect-TiO2NTs photoelectrode material obtained by the reaction is taken out and its surface is rinsed with DMF and anhydrous ethanol in sequence to remove excess solution and impurities. Finally, the prepared photoelectrode material is placed in a vacuum drying oven at 60 °C and dried overnight.

[0033] The prepared Pr MOFs / Defect-TiO2NTs photoelectrode material was used to conduct photoelectrocatalytic oxidation experiments on wastewater and hydrogen production. The experiments employed an H-type electrolytic cell, with Pr MOFs / Defect-TiO2NTs serving as both the photocathode and photoanode, and a working surface area of ​​2 cm². 2 The electrodes were spaced 2.5 cm apart. The photoelectrochemical testing electrolytic cell was equipped with a magnetic stirrer and a xenon lamp (POFILE PLS-SXE 300W). In the H-type electrolytic cell made of quartz glass, Pr MOFs / Defect-TiO2NTs served as the photocathode and photoanode, respectively, with a working surface area of ​​1 cm². 2 The electrodes were spaced 2.5 cm apart. A DC power supply was used. During the photoelectrocatalytic reaction, 2 ml samples were taken every 10 minutes. The concentration of organic pollutants during the reaction was measured using a UV-Vis spectrophotometer by observing the absorbance of characteristic peaks. The amount of hydrogen produced in the cathode chamber was then determined by gas chromatography using a total organic carbon (TOC) analyzer. Before the experiment, the prepared photoelectrode material was immersed in simulated wastewater in darkness for 30 minutes to reach adsorption-desorption equilibrium. The experimental conditions were as follows: pH 5, initial DMBA concentration 10 mg / L, applied voltage 3 V, and supporting electrolyte Na₂SO₄ with a concentration of 0.1 mol / L. After 120 minutes of reaction, DMBA was almost completely degraded, with a mineralization rate of 82.35%. The TOC removal rate of DMBA by Defect-TiO₂NTs was 54.5%, and the cathode hydrogen production rate reached 147.6 μmol / cm⁻¹. -2 h -1 The hydrogen production rate of the Defect-TiO2NTs cathode is only 18.7 μmol / cm³. -2 h -1 .

[0034] Example 2 A method for preparing a praseodymium-based MOF-enhanced defective TiO2 photoelectrode material includes the following steps: (1) Solution A was prepared by dissolving 0.5 mmol Pr(NO3)3·6H2O and 0.5 mmol Ce(NO3)3·6H2O in 2 mL of deionized water; solution B was prepared by dissolving 1 mmol terephthalic acid (H2BDC) in 10 mL of DMF. Solution A and solution B were mixed to prepare mixed solution C, and 0.00787 g of hexadecyltrimethylammonium bromide (CTAB) was added to mixed solution C. The pH of the solution was adjusted to 7.2 with ammonia water, and the solution was stirred at room temperature for 1 h to form a uniform and transparent solution at a stirring speed of 800 rpm.

[0035] (2) The prepared mixed solution was transferred to a polytetrafluoroethylene high-pressure reactor, and then the dried Defect-TiO2NTs sheet was placed in the high-pressure reactor and sealed; and transferred to an oven with programmed temperature control, heated to 140 °C at a heating rate of 2 °C / min, reacted for 36 h, and then cooled to room temperature.

[0036] (3) After the reaction is complete, the reaction vessel is naturally cooled to room temperature. The Pr-Ce MOFs / Defect-TiO2NTs photoelectrode material obtained by the reaction is taken out and its surface is rinsed with DMF and anhydrous ethanol in sequence to remove excess solution and impurities. Finally, the prepared photoelectrode material is placed in a vacuum drying oven at 60 °C and dried overnight.

[0037] The prepared Pr-Ce MOFs / Defect-TiO2NTs photoelectrode material was used to conduct photoelectrocatalytic oxidation experiments on wastewater and hydrogen production. The experiments were conducted using an H-type electrolytic cell, with Pr-Ce MOFs / Defect-TiO2NTs serving as both the photocathode and photoanode, and a working surface area of ​​2 cm². 2 The electrodes were spaced 2.5 cm apart. The photoelectrochemical testing electrolytic cell was equipped with a magnetic stirrer and a xenon lamp (POFILE PLS-SXE 300 W). In the H-type electrolytic cell made of quartz glass, Pr-Ce MOFs / Defect-TiO2NTs served as the photocathode and photoanode, respectively, with a working surface area of ​​1 cm². 2 The electrodes were spaced 2.5 cm apart. A DC power supply was used. During the photoelectrocatalytic reaction, 2 ml samples were taken every 5 minutes. The concentration of organic pollutants during the reaction was measured using a UV-Vis spectrophotometer by observing the absorbance of characteristic peaks. The amount of hydrogen produced in the cathode chamber was then determined by gas chromatography using a total organic carbon (TOC) analyzer. Before the experiment, the prepared photoelectrode was immersed in simulated wastewater in the dark for 30 minutes to reach adsorption-desorption equilibrium. The experimental conditions were as follows: pH 7, initial STZ concentration 10 mg / L, and voltage 3 V. After 120 minutes of reaction, STZ was almost completely degraded, with a mineralization rate of 92%. The TOC removal rate of STZ by Defect-TiO2NTs was 62.3%, and the cathode hydrogen production rate reached 153.8 μmol / cm³. -2 h -1 The hydrogen production rate of the Defect-TiO2NTs cathode is only 18.7 μmol / cm³. -2 h -1 .

[0038] Figure 1(a)-(b) are SEM images of the Pr MOFs / Defect-TiO2NTs photoelectrode materials prepared in Example 1 and Example 2, respectively.

[0039] Depend on Figure 1 (a) It can be seen that the rod-shaped Pr MOFs are uniformly distributed on the surface of Defect-TiO2NTs. This one-dimensional rod-shaped nano MOF structure itself has a high specific surface area, which, when combined with the high specific surface area of ​​the tubular structure, further expands the specific surface area of ​​the material and provides more active sites. The rod-shaped MOFs and the substrate nanotubes construct a multi-dimensional synergistic heterostructure interface, which helps to enhance light scattering and trapping capabilities, promotes the effective separation of photogenerated electron and hole pairs, and significantly inhibits their recombination. While improving the light energy utilization rate, it also optimizes the charge transport dynamics, greatly improves the photoelectric conversion efficiency, and thus significantly enhances the photoelectrocatalytic performance of the photoelectrode material.

[0040] Depend on Figure 1 (b) It can be seen that the Pr-Ce MOFs / Defect-TiO2NTs photoelectrode surface prepared by solvothermal method exhibits a petal-like morphology, which is uniformly distributed on the surface of the Defect-TiO2NTs matrix. Compared with Defect-TiO2NTs, the petal-like morphology of the loaded photoelectrode material increases the roughness and unevenness of the electrode surface, further enriches the catalytic active sites, and further enhances the light utilization efficiency.

[0041] Figure 2 (a)-(b) show the photocurrent response of the Pr MOFs / Defect-TiO2NTs and Pr-CeMOFs / Defect-TiO2NTs photoelectrode materials prepared in Examples 1 and 2, respectively. The photocurrent density of Pr MOFs / Defect-TiO2NTs is approximately 13 times that of TiO2NTs and 6 times that of Defect-TiO2NTs. The electrode loaded with Pr-Ce MOFs exhibits the highest photocurrent density, approximately 2.25 mA / cm². 2 It is approximately 11 times that of Defect-TiO2NTs. This demonstrates that the praseodymium-based MOF-modified Defect-TiO2NTs photoelectrode material significantly enhances the photocurrent density of the photoelectrode material. The Pr MOFs / TiO2NTs and Pr-Ce MOFs / TiO2NTs shown in the figure were prepared using TiO2NTs sheets, based on Examples 1 and 2, respectively.

[0042] Figure 3(a)-(b) show the impedance response of the Pr MOFs / Defect-TiO2NTs and Pr-CeMOFs / Defect-TiO2NTs photoelectrode materials prepared in Examples 1 and 22, respectively. The Defect-TiO2NTs photoelectrode loaded with Pr MOFs or Pr-Ce MOFs has a smaller Nyquist circle radius than the unmodified photoelectrode, indicating lower resistance. This means that Pr MOFs or Pr-Ce MOFs modification not only reduces the charge transfer resistance at the photoelectrode interface but also enhances the separation efficiency of photogenerated electrons and holes, thereby improving the charge transfer rate and conductivity of the photoelectrode during photoelectrocatalysis.

[0043] Figure 4 (a)-(c) are BET comparison diagrams of Defect-TiO2NTs and Pr MOFs / Defect-TiO2NTs and Pr-Ce MOFs / Defect-TiO2NTs photoelectrode materials prepared in Examples 1 and 2, respectively; where (a) is Defect-TiO2NTs, (b) is Pr MOFs / Defect-TiO2NTs, and (c) is Pr-Ce MOFs / Defect-TiO2NTs. The large specific surface area of ​​the photoelectrode before modification will give the material strong interfacial adsorption capacity and efficient electron transport capacity, which is beneficial to improving its photoelectrocatalytic activity.

[0044] Figure 5 (a)-(b) show the UV-Vis DRS spectra of the Defect-TiO2NTs photoelectrode materials prepared in Examples 1 and 2, respectively. The corresponding band gaps were indirectly derived by measuring the absorption wavelengths of the electrode materials. The band gaps of the photoelectrode materials decreased to 1.9 eV and 1.8 eV, respectively, further broadening the band structure, increasing the absorption of visible light, and promoting the migration and separation of charge carriers. The reduction in band gap makes it easier for photogenerated electrons to be excited while increasing the number of photogenerated charge carriers, thereby enhancing the photocatalytic activity. This indicates that the introduction of Pr MOFs and Pr-Ce MOFs effectively enhances the light absorption efficiency and photocatalytic activity of the Defect-TiO2NTs photoelectrode.

[0045] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a praseodymium-based MOF-enhanced defective TiO2 photoelectrode material, characterized in that: Includes the following steps: (1) Dissolve praseodymium rare earth metal salt in water to prepare mixed solution A; the rare earth metal salt is one or both of PrNO3·6H2O and CeNO3·6H2O; (2) Dissolve the organic ligand in an organic solvent to prepare a mixed solution B; the concentration of the organic ligand is 0.04-0.09 mol / L; (3) Mix the mixed solution A and mixed solution B by magnetic stirring, then put them into the matrix and carry out a hydrothermal reaction. After the reaction is completed, the praseodymium-based MOF-enhanced defect TiO2 photoelectrode material is obtained; the matrix is ​​defective titanium dioxide nanotubes.

2. The preparation method according to claim 1, characterized in that: In step (1), when the rare earth metal salt is PrNO3·6H2O, the concentration of PrNO3·6H2O is 0.02-0.04 mol / L.

3. The preparation method according to claim 1, characterized in that: In step (1), when the rare earth metal salts are PrNO3·6H2O and CeNO3·6H2O, the concentration of PrNO3·6H2O is 0.03-0.05 mol / L and the concentration of CeNO3·6H2O is 0.03-0.05 mol / L.

4. The preparation method according to claim 1, characterized in that: In step (2), the organic solvent is N,N-dimethylformamide.

5. The preparation method according to claim 1, characterized in that: In step (2), the organic ligand is terephthalic acid.

6. The preparation method according to claim 1, characterized in that: In step (3), the temperature of the hydrothermal reaction is 140-160℃ and the time is 24-48h.

7. A praseodymium-based MOF-enhanced defective TiO2 photoelectrode material prepared by the preparation method according to any one of claims 1-6.

8. The application of a praseodymium-based MOF-enhanced defective TiO2 photoelectrode material prepared by the preparation method according to any one of claims 1-6 in the treatment of high-concentration, recalcitrant organic wastewater and in synergistic photoelectrocatalytic hydrogen production.

Images