Preparation method and application of double-ligand MOFs photocatalyst

Abstract

The invention provides a preparation method and application of a double-ligand MOFs photocatalyst, and relates to the technical field of preparation of MOFs photocatalysts. According to the double-ligand MOFs photocatalyst, an H2TCPP ligand is introduced into MOFs (NU-1000) by using an in-situ synthesis method, and meanwhile, a part of ligand 1, 3, 6, 8-quadruplex (p-benzoic acid) pyrene (H4TBAPy) is reserved, so that the double-ligand MOFs photocatalyst is prepared; by introducing H2TCPP, transfer of interface electrons can be promoted, an energy band structure is adjusted, and the absorption efficiency of the catalyst to visible light and the photocatalytic activity of the catalyst are remarkably improved. According to the double-ligand MOFs photocatalyst prepared by the preparation method provided by the invention, NTP can be efficiently removed through photocatalytic degradation, and an effective method is provided for degradation of NTP.

Description

Technical Field

[0001] The present invention relates to the technical field of MOFs photocatalyst preparation, and in particular to a preparation method and application of a dual-ligand MOFs photocatalyst. Background Art

[0002] Neonicotinoid insecticides are primarily used to control feeding pests such as aphids, planthoppers, and mealybugs. Excessive use of these insecticides has led to environmental residues and serious ecological problems. The high stability and toxicity of NTPs, in particular, make them a major environmental threat. These substances are difficult to degrade in water and exhibit significant toxicity to human embryonic stem cells, potentially posing a risk of teratogenicity. Furthermore, the use of NTPs has been identified as a major contributor to the decline in the numbers of both wild and domesticated bees, posing a serious threat to pollination. Therefore, effective reduction of NTP residues remains a pressing concern. Current degradation methods primarily include microbial degradation, electrocatalysis, and low-temperature plasma technology. However, these methods often suffer from limitations in reaction conditions, low efficiency, and high energy consumption. In contrast, photocatalytic degradation has garnered widespread attention due to its mild operating conditions and environmentally friendly properties.

[0003] MOFs are developing rapidly in the field of photocatalysis and have broad application prospects. Most current research focuses on improving the efficiency of photogenerated carrier separation and preventing carrier recombination, for example, by combining MOFs with other materials to form heterojunctions. However, there are few studies on improving photocatalytic activity by adjusting the organic ligands of MOFs, and the technology is not mature. A common method for modifying photocatalytic activity is to introduce amino ligands into MOFs to form a coupling effect with other ligands, promote visible light absorption, and thus effectively improve photocatalytic performance. However, due to topological structure and synthetic thermodynamic limitations, it is still difficult to simultaneously replace most of the ligands in the MOFs synthesis system and introduce larger conjugated structures into the MOFs synthesis system. The catalyst has limited absorption efficiency of visible light, which limits the improvement of its catalytic performance.

[0004] In view of this, it is necessary to design an improved preparation method and application of dual-ligand MOFs photocatalyst to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method of a dual-ligand MOFs photocatalyst and its application.

[0006] To achieve the above-mentioned object of the invention, on the one hand, the present invention provides a method for preparing a dual-ligand MOFs photocatalyst, comprising the following steps:

[0007] ZrOCl2·8H2O and benzoic acid were dissolved in a first organic solvent and heated at 100°C for 1 hour to obtain a mixed solution. H4TBAPy and H2TCPP were added to the mixed solution and reacted at 120°C for 24 hours. After the reaction, the solid phase was collected and mixed with trifluoroacetic acid and a second organic solvent. The resulting mixed solution was reacted at 120°C for 24 hours to prepare a dual-ligand MOFs photocatalyst.

[0008] Preferably, the mass ratio of H4TBAPy to H2TCPP is (70-77):(3-10).

[0009] Preferably, the mass ratio of ZrOCl2·8H2O to benzoic acid is 1.93:54.

[0010] Preferably, the first organic solvent is any one of methanol, ethanol, ethylene glycol, DMSO, and DMF; the second organic solvent is any one of methanol, ethanol, ethylene glycol, DMSO, and DMF.

[0011] Preferably, the first organic solvent is DMF; the mass to volume ratio of ZrOCl2·8H2O and benzoic acid is 193 mg:5.4 g:12 mL.

[0012] Preferably, the second organic solvent is DMF; the volume ratio of trifluoroacetic acid to HCl is 0.11:4.

[0013] Preferably, the mass ratio of H4TBAPy to H2TCPP is 75:5.

[0014] On the other hand, the present invention provides a dual-ligand MOFs photocatalyst, wherein the dual-ligand MOFs photocatalyst has a rod-like structure, an aspect ratio of 5:1, and a specific surface area of ​​626.39 m 2 / g.

[0015] In particular, the dual-ligand MOFs photocatalyst prepared by the preparation method proposed in the present invention can be applied to the photocatalytic degradation of neonicotinoid insecticides, especially the photocatalytic degradation of NTP.

[0016] The beneficial effects of the present invention are:

[0017] The present invention provides a method for preparing a dual-ligand MOFs photocatalyst. The method introduces an H2TCPP ligand into MOFs (NU-1000) by using an in-situ synthesis method, while retaining part of the ligand 1,3,6,8-tetramer (p-benzoic acid) pyrene (H4TBAPy) component to prepare a MOFs photocatalyst with a dual-ligand structure. The introduction of H2TCPP promotes the transfer of interfacial electrons and adjusts the energy band structure, thereby significantly improving the catalyst's absorption efficiency for visible light and enhancing the catalyst's photocatalytic activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a diagram of the preparation mechanism of the dual-ligand MOFs photocatalyst proposed in the present invention;

[0019] Figure 2 The XRD patterns and FTIR patterns of the photocatalysts prepared in Examples 1 to 3 and Comparative Example 1 of the present invention are shown;

[0020] Figure 3 The SEM images of the photocatalysts prepared in Examples 1 to 3 of the present invention and Comparative Example 1 are shown;

[0021] Figure 4 Graph showing the optical properties of the photocatalysts prepared in Examples 1 to 3 and Comparative Example 1 of the present invention;

[0022] Figure 5 The kinetic results of the photocatalytic degradation of NTP obtained in Examples 1 to 3 of the present invention are as follows;

[0023] Figure 6 The photocatalytic degradation mechanism of NTP by TPNU-2 prepared in Example 2 of the present invention;

[0024] Figure 7 The experimental results of TPNU-2 cyclic degradation of NTP and the FTIR images of TPNU-2 before and after degradation are shown;

[0025] Figure 8 The Zeta potential, reaction rate constant and adsorption removal rate of TPNU-2 in degradation of NTP under different pH conditions;

[0026] Figure 9 This is the result of TPNU-2 degrading NTP in different environments. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] It should also be noted here that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the solutions of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0029] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0030] See also Figure 1 As shown, the present invention provides a method for preparing a dual-ligand MOFs photocatalyst, comprising the following steps:

[0031] ZrOCl2·8H2O and benzoic acid were dissolved in a first organic solvent and heated at 100°C for 1 hour to obtain a mixed solution. H4TBAPy and H2TCPP were added to the mixed solution and reacted at 120°C for 24 hours. After the reaction, the solid phase was collected and mixed with trifluoroacetic acid and a second organic solvent. The obtained mixed solution was reacted at 120°C for 24 hours. The solid product obtained by the reaction was collected and dried to obtain a dual-ligand MOFs photocatalyst.

[0032] In some embodiments, the mass ratio of ZrOCl2·8H2O to benzoic acid is 1.93:54, the first organic solvent is any one of methanol, ethanol, ethylene glycol, DMSO, and DMF, preferably DMF, and the ratio of the mass of ZrOCl2·8H2O and benzoic acid to the volume of DMF is 193 mg:5.4 g:12 mL; the second organic solvent is any one of methanol, ethanol, ethylene glycol, DMSO, and DMF, preferably DMF, and the volume ratio of trifluoroacetic acid to DMF is 0.11:4.

[0033] In some embodiments, the mass ratio of H4TBAPy to H2TCPP is (70-77):(3-10).

[0034] The preparation method and application of the dual-ligand MOFs photocatalyst proposed in the present invention are further described below with reference to specific examples:

[0035] Example 1

[0036] This embodiment prepares a dual-ligand MOFs photocatalyst, and the preparation method thereof comprises the following steps:

[0037] 193 mg of ZrOCl2·8H2O and 5.4 g of benzoic acid were dissolved in 12 mL of DMF (analytical grade) and heated at 100°C for 1 h to obtain a mixed solution; 77 mg of H4TBAPy and 3 mg of H2TCPP ligand were added to the cooled mixed solution, mixed evenly, and reacted at 120°C for 24 h. After the reaction, the resulting mixture was centrifuged and washed three times with DMF; 0.33 mL of trifluoroacetic acid (analytical grade) and 12 mL of DMF were added to the washed solid, heated at 120°C for 24 h, and the product after heating was washed 3-5 times with DMF and acetone, respectively, and soaked in acetone for 12 h, with the acetone replaced every 2 h. The solid phase was collected by centrifugation and dried at 120°C for 12 h to obtain a dual-ligand MOFs photocatalyst named TPNU-1.

[0038] Example 2

[0039] This embodiment prepares a dual-ligand MOFs photocatalyst, and the preparation method thereof comprises the following steps:

[0040] 193 mg of ZrOCl2·8H2O and 5.4 g of benzoic acid were dissolved in 12 mL of DMF (analytical grade) and heated at 100°C for 1 h to obtain a mixed solution; 75 mg of H4TBAPy and 5 mg of H2TCPP ligand were added to the cooled mixed solution, mixed evenly, and reacted at 120°C for 24 h. After the reaction, the resulting mixture was centrifuged and washed three times with DMF; 0.33 mL of trifluoroacetic acid (analytical grade) and 12 mL of DMF were added to the washed solid, heated at 120°C for 24 h, and the product after heating was washed 3-5 times with DMF and acetone, respectively, and soaked in acetone for 12 h, with the acetone replaced every 2 h. The solid phase was collected by centrifugation and dried at 120°C for 12 h to obtain a dual-ligand MOFs photocatalyst named TPNU-2.

[0041] Example 3

[0042] This embodiment prepares a dual-ligand MOFs photocatalyst, and the preparation method thereof comprises the following steps:

[0043] 193 mg of ZrOCl2·8H2O and 5.4 g of benzoic acid were dissolved in 12 mL of DMF (analytical grade) and heated at 100°C for 1 h to obtain a mixed solution; 70 mg of H4TBAPy and 10 mg of H2TCPP ligand were added to the cooled mixed solution, mixed evenly, and reacted at 120°C for 24 h. After the reaction, the resulting mixture was centrifuged and washed three times with DMF; 0.33 mL of trifluoroacetic acid (analytical grade) and 12 mL of DMF were added to the washed solid, heated at 120°C for 24 h, and the product after heating was washed 3-5 times with DMF and acetone, respectively, and soaked in acetone for 12 h, with the acetone replaced every 2 h. The solid phase was collected by centrifugation and dried at 120°C for 12 h to obtain a dual-ligand MOFs photocatalyst named TPNU-3.

[0044] Comparative Example 1

[0045] The only difference between Comparative Example 1 and Example 1 is that only a single ligand H4TBAPy is used to prepare the MOFs material NU-1000. The specific preparation method is as follows:

[0046] 193 mg of ZrOCl2·8H2O and 5.4 g of benzoic acid were dissolved in 12 mL of DMF (analytical grade) and heated at 100°C for 1 hour to obtain a mixed solution. 80 mg of H4TBAPy ligand was added to the cooled mixed solution, mixed evenly, and reacted at 120°C for 24 hours. After the reaction, the resulting mixture was centrifuged and washed three times with DMF. 0.33 mL of trifluoroacetic acid (analytical grade) and 12 mL of DMF were added to the washed solid, heated at 120°C for 24 hours, and the product was washed 3-5 times with DMF and acetone, respectively, and soaked in acetone for 12 hours, with the acetone replaced every 2 hours. The solid phase was collected by centrifugation and dried at 120°C for 24 hours to obtain NU-1000, which can be used as a photocatalyst.

[0047] The XRD patterns and FTIR patterns of the photocatalysts prepared in Examples 1 to 3 and Comparative Example 1 are shown as follows: Figure 2 Figure (a) and Figure 2 As shown in Figure (b), Figure 2 As can be seen from Figure (a), NU-1000 has characteristic peaks at 2θ=5.2, 7.4 and 11.2, which are consistent with the characteristic peak positions of the simulated NU-1000. These characteristic peaks correspond to the (100), (200) and (201) crystal planes of NU-1000, respectively, indicating the successful synthesis of NU-1000. Secondly, the characteristic peak positions of TPNU-1, TPNU-2 and TPNU-3 prepared in Examples 1 to 3 are the same as those of NU-1000, indicating that H2TCP was introduced into NU-1000. The process of adding H2TCPP does not affect the integrity and crystallinity of the NU-1000 framework, but the peak widths of TPNU-1, TPNU-2, and TPNU-3 become wider than those of NU-1000, indicating that the introduction of H2TCPP may change the size of the NU-1000 grains. In addition, the peak intensity of TPNU-(1-3) at 2θ=7.4 is enhanced, which may be caused by the strong interaction between H2TCPP and zirconium oxygen clusters. When the amount of H2TCPP added is 5 mg (Example 2), the crystallinity is the best.

[0048] from Figure 2 As can be seen in Figure (b), H2TCPP and H4TBAPy have a peak at 1696 cm -1 There is a characteristic peak of -COOH stretching vibration at 1613cm. After forming TPNU-1, TPNU-2 and TPNU-3, the absorption peak disappears and is replaced by -1 and 1422cm -1 The occurrences are respectively attributed to -COO - The symmetric and asymmetric stretching vibration absorption peaks of the group are at 1550 cm -1 and 1192cm -1The absorption peaks due to the stretching and bending vibrations of the porphyrin macrocycle appeared at 656 cm, indicating that H2TCPP and NU-1000 had successfully reacted and H2TCPP was doped in NU-1000. -1 The peak at corresponds to the O-Zr bond, indicating that Zr 4+ The coordination exists in TPNU-1, TPNU-2, TPNU-3 and NU-1000, indicating that TPNU-(1-3) was successfully synthesized.

[0049] The SEM images of the photocatalysts prepared in Examples 1 to 3 and Comparative Example 1 are as follows: Figure 3 As shown, Figure 3 Figure (a) corresponds to NU-1000 of Comparative Example 1, Figure 3 Figure (b) corresponds to TPNU-1 of Example 1, Figure 3 Figure (c) corresponds to TPNU-2 of Example 2, Figure 3 Figure (d) corresponds to TPNU-3 of Example 3, Figure 3 Figure (e) corresponds to the SEM image and EDS-Mapping image of TPNU-2. The results show that the surface of NU-1000 in Figure (a) is smooth, with clear outlines, and appears as a regular rod-shaped crystal with a length of 2.5 μm, a diameter of 0.5 μm, and a specific surface area of ​​626.39 m 2 / g, with an average pore size of 2.2228nm; Figures (b) to (e) show that the sample has a rod-like structure, and there are rough flaky structures on the surface of the rod-like structure, which may be photoactive sites; EDS-Mapping diagrams show that Zr, C, O and N are uniformly distributed in TPNU-2, which is consistent with the analysis results of XRD and FTIR.

[0050] Furthermore, in order to explore the application performance of the catalyst prepared in the embodiment of the present invention in photocatalytic degradation, the optical properties of the photocatalysts prepared in Examples 1 to 3 and Comparative Example 1 were evaluated using UV-vis spectroscopy. The results are as follows: Figure 4 As shown, Figure 4 Figure (a) corresponds to the UV spectra of NU-1000 and TPNU-(1-3). Figure 4 Figure (b) corresponds to the band gap diagram of NU-1000 and TPNU-(1-3), Figure 4 Figure (c) corresponds to the photocurrent diagram of NU-1000 and TPNU-(1-3), Figure 4 Figure (d) corresponds to the impedance diagram of NU-1000 and TPNU-2, Figure 4 Figure (e) corresponds to the PL of NU-1000 and TPNU-(1-3), Figure 4Figure (f) corresponds to the fluorescence emission and excitation spectra of H2TCPP and H4TBAPy. Figure (a) shows that the absorption peak edge of NU-1000 extends to 500nm. After doping with H2TCPP, the absorption peak edge of TPNU-(1-3) extends to 680nm, and TPNU-2 shows the highest light utilization efficiency, with its visible light absorption edge at 715nm. According to (αhν) 2 and photon energy (hν), and combined with Figure (b), the band gaps (E g ) are 2.86, 2.67, 2.66 and 2.40 eV respectively; Figure (c) shows that NU-1000 exhibits weaker photocurrent intensity, lower current density and slower response to light, while TPNU-2 exhibits significantly higher photocurrent intensity, faster response to light and better current density, which indicates that the addition of H2TCPP improves the separation efficiency of photogenerated electron-hole pairs, and TPNU-2 exhibits the highest photocurrent density, which may be due to the improvement of electron transfer through ligand engineering; Figure (d) shows that the semicircular diameter of NU-1000 is much larger than that of TPNU-2, indicating that TPNU-2 has higher carrier transfer efficiency; Figure (e) shows that compared with the NU-1000 material, TPNU-2 has a stronger absorption The low absorption rate indicates that TPNU-2 is highly efficient in carrier migration and separation, allowing more absorbed light energy to be effectively utilized for charge transport, thereby improving performance in applications such as photocatalysis or photochemical reactions. Figure (f) shows that the absorption spectrum of the porphyrin ligand H2TCPP, with a characteristic peak centered at 415 nm, highly overlaps with the emission spectrum of the ligand H4TBAPy used to synthesize NU-1000, with the emission peak of H2TCPP near 645 nm. Furthermore, the absorption spectra corresponding to H2TCPP and H4TBAPy highly overlap, suggesting the potential for significantly promoting the construction of efficient energy transfer MOFs, in which H2TCPP and H4TBAPy serve as energy donors and energy acceptors, respectively. These results demonstrate that TPNU-(1-3) prepared in Examples 1 to 3 possess excellent optical and electrochemical properties.

[0051] In addition, the present invention also tested the photocatalytic degradation activity of the photocatalysts prepared in Examples 1-3. The specific test method is as follows: Nitenpyram (NTP) was used as the degradation target, 10 mg of the photocatalyst was added to a NTP solution with a pH of 7.0 and a concentration of 20 mg / L, and dark adsorption was first performed for 20 minutes to establish adsorption-desorption equilibrium, and then illumination was performed for 20 minutes to achieve NTP degradation. The results were compared with the control group without any catalyst (the "NTP" group in Figures (a)-(b)). The kinetic study results of the degradation process are shown in FIG. Figure 5 As shown, Figure 5Figure (a) shows the adsorption kinetic curves of NTP degradation by catalysts with different loading amounts and their ligands. Figure 5 Figure (b) shows the kinetic constant corresponding to the curve in Figure (a). Figure 5 Figure (c) shows the pseudo-first-order kinetics of NTP degradation by different catalysts. Figure 5 Figure (d) is a graph showing the removal rate of NTP degradation by different catalysts. Analyzing the figures, Figure (a) shows that NTP is basically not degraded in the absence of a catalyst, which indicates that NTP has a fairly strong stability under natural conditions; Figure (b) shows that in the presence of NU-1000, H2TCPP, H4TBAPy, TPNU-1, TPNU-2, and TPNU-3, the removal rates of NTP are 57.10% (adsorption amount is 42.95%), 6.12%, 8.61%, 71.31%, 75.01%, and 63.01%, respectively. Although NU- 1000 showed strong adsorption performance, but its photodegradation effect was not ideal due to its limited electron-hole conduction capacity. This limitation shows that although the material can effectively adsorb pollutants, the efficiency of carriers in promoting the degradation process is poor, which hinders its photodegradation performance. Compared with NU-1000 and H2TCPP, the photocatalytic degradation efficiency of the mixed ligand material photocatalyst TPNU-(1-3) was significantly improved, with a significant removal rate of more than 60%. The rate constant k of TPNU-2 was 0.0734min -1, which is significantly higher than the k values ​​corresponding to NU-1000, TPNU-1, TPNU-3, H4TBAPy and H2TCPP. The value is 15.62 times that of NU-1000, 19.31 times that of H4TBAPy, and 24.46 times that of H2TCPP. These results show that TPNU-2 has significantly enhanced photocatalytic activity; the NTP removal rates of TPNU-1 and TPNU-3 are 71.31% and 63.10%, respectively. The k value of TPNU-2 is 1.40 times that of TPNU-1 and 1.80 times that of TPNU-3, which indicates that the photocatalytic activity of TPNU-2 is significantly enhanced; in order to compare the photocatalytic performance of TPNU-2, this paper uses MOFs materials with H2TCPP and H4TBAPy as organic ligands to carry out photodegradation experiments on NTP. These MOFs are PC N-222, PCN-224, MOF-525, ROD-7 and Tb-CU-1, among which PCN-222, PCN-224 and MOF-525 use H2TCPP as organic ligand, ROD-7 and Tb-CU-1 use H4TBAPy as organic ligand, and the results are shown in Figure (c)-Figure (d). PCN-222, PCN-224, MOF-252, ROD- 7. The degradation efficiencies of Tb-CU-10 and TPNU-2 for NTP were 8.08%, 7.17%, 8.67%, 13.17%, and 8.21%, respectively. Furthermore, the k value of TPNU-2 was 11.22, 32.77, 25.66, 17.48, and 58.25 times that of PCN-222, PCN-224, MOF-252, Tb-CU-10, and ROD-7, respectively. These results indicate that the mixed ligand structure of TPNU-2 enhances its photocatalytic degradation ability. Compared to other single-ligand MOFs, TPNU-2 exhibits superior performance in NTP degradation.

[0052] The photocatalytic degradation mechanism of TPNU-2 is as follows: The CB (conduction band) and VB (valence band) of NU-1000 are -0.87 and 1.99V respectively. Its band structure determines that higher energy is required to excite the generation of electron-holes. In addition, NU-1000 also has a wide band gap. When irradiated with light, it takes more energy for electrons to transfer from VB to CB. After doping with H2TCPP, TPNU-2 has a smaller band gap, and photogenerated electrons-holes can quickly transfer from VB to CB. The CB and VB of TPNU-2 are -8.5 and 1.75V (vs. NHE), which is much faster than O2 (O2 / ·O2 - ) has a more negative redox potential (-0.33 eV), and electrons migrate from the VB of TPNU-2 to the CB. - Formed with O2·O2 - At the same time, the CB of TPNU-2 acts as an active site and interacts with the activated O2- Degrade NTP. In addition, O2 - Can be used with h + Reaction generation 1 O2 reacts with H to form H + 2O,h + Can directly react with H + 2O reacts to generate O2, which can directly participate in the photocatalytic degradation of NTP and provide O2 for the main active substances. The specific degradation mechanism is as follows Figure 6 As shown, the possible degradation formula of TPNU-2 is as follows:

[0053] TPNU-2+hv→TPNU-2(e CB - )+TPNU-2(h VB + ) (5-1)

[0054] TPNU-2+hv→TPNU-2(e CB - )+TPNU-2(h VB + ) (5-2)

[0055] TPNU-2(e CB - )+·O2→TPNU-2(e CB - )+·O2 - (5-3)

[0056] O2 - +TPNU-2(e CB - )+2H→H + 2O (5-4)

[0057] O2 - +TPNU-2(h VB + )→ 1 O2 (5-5)

[0058] 2H2O+4h + →O + 2+4H + (5-6)

[0059] TPNU-2(h VB + )→degradation products (5-7)

[0060] TPNU-2(h VB + )→degradation products (5-8)

[0061] O2 - +NTP→degradation product (5-9)

[0062] After the degradation experiment was completed, TPNU-2 was recovered and subjected to repeated degradation cycle experiments under the same conditions. The experimental results of 10 degradation cycles were as follows: Figure 7 As shown in Figure (a), the results show that after the 10th cycle, the removal rate of NTP by TPNU-2 can still reach more than 60%. The FTIR images of TPNU-2 before and after degradation are shown in Figure (a). Figure 7 As shown in Figure (b), there was no shift in the infrared spectrum before and after the reaction, indicating that TPNU-2 has good repeatability and stability.

[0063] Based on the above analysis results, the optimal pH conditions for TPNU-2 to degrade NTP were further explored during the experiment. This is because changes in pH will change the electrical properties and surface charge properties of the catalyst, thereby affecting its catalytic degradation performance. During the experiment, 0.1 mol / L HCl and 0.10 mol / L NaOH were used as pH adjustment solutions to accurately adjust the initial pH of the NTP solution to 3.0, 5.0, 7.0, and 9.0. The effect of pH on the Zeta potential diagram of TPNU-2 is shown in Figure 2. Figure 8 As shown in Figure (a), the reaction rate constant and adsorption removal rate under different pH conditions are as follows Figure 8 As shown in Figure (b), it can be seen from the figure that as the pH increases from 3.0 to 9.0, the degradation efficiency of NTP increases from 60.58% to 73.28%. The photocatalytic results show that TPNU-2 exhibits the best catalytic activity under neutral conditions (pH = 7.0), with a degradation rate constant of 0.08510min -1 The inset in Figure (a) shows that the zero charge point of TPNU-2 is 7.02, which means that the material surface is positively charged at pH < 7.02 and negatively charged at pH > 7.02. In addition, TPNU-2 exhibits the strongest oxidation ability under neutral conditions. This may be because the pH value at this time is close to the zero potential of the material, making the electrostatic interaction between the NTP molecules and the catalyst surface weakest, thus facilitating the photocatalytic degradation reaction. In a weakly acidic environment (pH < 7.02), the TPNU-2 surface is positively charged, generating a strong electrostatic attraction with the negatively charged NTP molecules. This not only enhances the adsorption capacity of NTP on the catalyst surface but also significantly improves the degradation efficiency. In contrast, under weakly or strongly alkaline conditions (pH > 7.02), the material surface becomes negatively charged, and the electrostatic interaction between it and the NTP molecules changes from attraction to repulsion. This not only weakens the adsorption capacity of the reactants but also reduces the photocatalytic oxidation efficiency, ultimately leading to a decline in degradation performance.

[0064] In actual application scenarios, interfering ions may exist in NTP solutions, which will coexist with pollutants in natural water bodies. These ions can participate in the photocatalytic degradation process, which may enhance or inhibit the decomposition of NTP, or may be detrimental to degradation. Therefore, five common inorganic anions Cl - 、SO4 2- 、HCO3 - 、H2PO4 - and HPO4 2- When present, and 5 inorganic cations Na + Mg 2+ 、Cu 2+ 、Al 3+ and Zn 2+ (Specific material sources are NaCl, MgCl2, CuSO4, AlCl3 and ZnSO4) in the presence of interfering ions, the effect of interfering ions on the photocatalytic degradation activity, the degradation results under the condition of the presence of anions are as follows Figure 9 As shown in Figure (a), the results show that under the condition of NTP concentration of 20 mg / L, Cl - 、SO4 2- 、HCO3 - 、H2PO4 - and HPO4 2- The degradation efficiencies were 71.36%, 73.63%, 74.28%, 70.31% and 70.06% respectively. The presence of most anions (Cl - 、SO4 2- 、HCO3 - ) has little effect on NTP degradation. However, H2PO4 - and HPO4 2- The presence of H2PO4 resulted in a slight decrease in removal efficiency, which may be due to the competition between these anions and NTP for active sites on the material surface. - and HPO4 2- Provide acidic and alkaline environments respectively, while NTP has the best removal efficiency under neutral conditions. - and HPO4 2- In the presence of , the degradation efficiency decreased, which was consistent with the results of the pH experiment.

[0065] The degradation results in the presence of cations are as follows Figure 9As shown in Figure (b), the results show that under the coexistence of cations, the degradation efficiency of NTP is maintained in the range of 65.19-70.50%. Cations of different valences have no significant effect on the photocatalytic degradation efficiency of NTP, indicating that these cations have no significant interference with the photocatalytic process within the experimental concentration range. At the same time, the effects of various organic substances (such as fulvic acid, ascorbic acid, citric acid, etc.) on the degradation were also explored during the experiment. The results are shown in Figure (b). Figure 9 As shown in Figure (c), the results show that the reaction rate constant of the system containing fulvic acid, ascorbic acid and citric acid is only slightly lower than that under normal conditions, indicating that the TPNU-2 system has strong anti-interference ability.

[0066] In particular, water samples will also affect the photocatalytic process in practical applications. In the experiment, tap water, river water, and distilled water containing NTP were selected as water samples. The test results of TPNU-2 on the degradation efficiency of NTP in different water samples are as follows: Figure 9 As shown in Figure (d) in the figure, the degradation removal rate is stable within the range of 73.53-75.01%. In addition, the degradation efficiency in river water shows a slight decrease compared to the distilled water system. This difference may be due to the interference of complex components naturally present in river water, such as dissolved organic matter and inorganic ions, on the photocatalytic process. These substances may reduce the efficiency of light energy utilization by competing for light absorption or occupying the active sites of the catalyst.

[0067] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a dual-ligand MOFs photocatalyst, characterized in that: The steps include: ZrOCl2·8H2O and benzoic acid were dissolved in a first organic solvent and heated at 100°C for 1 hour to obtain a mixed solution. H4TBAPy and H2TCPP were added to the mixed solution and reacted at 120°C for 24 hours. After the reaction, the solid phase was collected and mixed with trifluoroacetic acid and a second organic solvent. The resulting mixed solution was reacted at 120°C for 24 hours to prepare a dual-ligand MOFs photocatalyst.

2. The preparation method according to claim 1, characterized in that The mass ratio of H4TBAPy to H2TCPP is (70-77):(3-10).

3. The preparation method according to claim 1, characterized in that The mass ratio of ZrOCl2·8H2O to benzoic acid is 1.93:

54.

4. The preparation method according to claim 1, characterized in that The first organic solvent is any one of methanol, ethanol, ethylene glycol, DMSO, and DMF; the second organic solvent is any one of methanol, ethanol, ethylene glycol, DMSO, and DMF.

5. The preparation method according to claim 4, characterized in that The first organic solvent is DMF; the mass ratio of ZrOCl2·8H2O and benzoic acid to the volume of DMF is 193 mg:5.4 g:12 mL.

6. The preparation method according to claim 4, characterized in that The second organic solvent is DMF; the volume ratio of trifluoroacetic acid to DMF is 0.11:

4.

7. The preparation method according to claim 2, characterized in that The mass ratio of H4TBAPy to H2TCPP is 75:

5.

8. A dual-ligand MOFs photocatalyst prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The dual-ligand MOFs photocatalyst has a rod-like structure with an aspect ratio of 5:1 and a specific surface area of ​​626.39 m 2 / g.

9. Use of the dual-ligand MOFs photocatalyst prepared by the preparation method according to any one of claims 1 to 7 or the dual-ligand MOFs photocatalyst according to claim 8 in the photocatalytic degradation of neonicotinoid insecticides.

10. Use of the dual-ligand MOFs photocatalyst prepared by the preparation method according to any one of claims 1 to 7 or the dual-ligand MOFs photocatalyst according to claim 8 in photocatalytic degradation of NTP.

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