Preparation method of cluster defect structure UiO-66 nanoparticles with piezoelectric effect
The cluster defect structure UiO-66 nanoparticles prepared by the solvothermal method solve the problem of uncontrollable UiO-66 doping, achieve uniform size and efficient piezoelectric catalytic performance of the nanoparticles, and improve the practical application effect of the material.
Patent Information
- Application Number
- CN202511744466.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-25
- Publication Date
- 2026-02-24
AI Technical Summary
The doping process of existing UiO-66 is uncontrollable due to the difference in kinetics between Zr4+ and Zn2+, resulting in the formation of uncontrollable cluster defects in the crystal. This leads to non-uniform morphology and wide size distribution of nanoparticles, and the piezoelectric catalytic performance is far lower than theoretical predictions.
A one-step solvothermal method was used to prepare UiO-66 nanoparticles with piezoelectric cluster defect structures by controlling the ultrasonic treatment of hafnium chloride, zirconium chloride, zinc nitrate and terephthalic acid in N,N-dimethylformamide solution, followed by heating and cooling, centrifugation, washing and drying.
The nanoparticles achieved uniform size distribution, significantly enhanced piezoelectric effect, excellent catalytic performance, strong electron-hole separation capability, and greatly improved piezoelectric catalytic performance.
Smart Images
Figure CN121554760A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing nanoparticles with piezoelectric effect. Background Technology
[0002] With the global depletion of fossil energy and the continuous rise in CO2 emissions, the development of technologies that directly convert low-grade mechanical energy (tidal, water flow, human movement) into chemical energy has become a hot topic. Piezoelectric catalysis utilizes the non-centrosymmetric strain-polarization-charge separation mechanism of crystals to drive water splitting for hydrogen production, dye degradation, and CO2 reduction at room temperature and without bias voltage, and is regarded as a new "self-powered" green chemistry pathway.
[0003] Advantages and bottlenecks of the UiO-66 platform: The metal-organic framework UiO-66, with Zr as nodes, possesses a stable three-dimensional network structure composed of 12-coordinated hyperoctahedral [Zr6O4(OH)4] secondary structural units, and boasts an ultra-high specific surface area (>1000m²). 2 With its piezoelectricity d / g, regular pores (0.8nm~1.1nm), excellent chemical and thermal stability (pH=1~12, 500℃), and modifiability, intrinsic UiO-66 exhibits outstanding performance in catalysis and energy storage. However, intrinsic UiO-66 belongs to the centrosymmetric Fd-3m space group, and its piezoelectric coefficient d 33 Approaching zero, it cannot generate an effective piezoelectric response, which greatly limits its application in the field of piezoelectric catalysis.
[0004] To impart piezoelectric properties to UiO-66, researchers attempted to create defects at its nodes through heterometallic doping (such as oxygen vacancies Vö, metal vacancies VM, and heterometallic substitution) to break structural symmetry and form "cluster defect dipoles." Theoretical calculations show that when the Zr / Hf nodes are partially filled with Zn... 2+ When an ionic radius of 0.74 Å is substituted and coupled to form an oxygen vacancy, a defect level of approximately 1.55 eV can be introduced into the material's bandgap, theoretically increasing its piezoelectric coefficient d. 33 The surface area increased significantly from 0 pm / V to 38 pm / V, while maintaining a high specific surface area (BET > 800 m²). 2 / g). However, realizing this theoretical prospect faces severe technical challenges. Existing synthesis methods, especially the traditional hydrothermal / solvothermal methods, suffer from limitations in preparing Zn-doped UiO-66 due to Zr 4+ With Zn 2+The hydrolysis rate and coordination kinetics under hydrothermal conditions differ greatly, leading to uncontrollable doping. This inherent defect in the synthesis technique results in the following problems in the final product: (1) uncontrollable and excessive cluster defects are formed in the crystal, destroying long-range order; (2) the morphology of the nanoparticles is non-uniform, with a wide size distribution range, making it difficult to obtain high-quality nanomaterials; (3) the expected piezoelectric structure (cluster defect dipole) cannot be effectively constructed, resulting in the actual piezoelectric catalytic performance of the material (such as hydrogen production efficiency or reactive oxygen generation capacity) being far lower than theoretical predictions. Therefore, developing a new method to overcome the above-mentioned differences in metal ion kinetics and achieve controllable doping, thereby preparing UiO-66 nanomaterials with regular morphology, uniform size, and excellent and stable piezoelectric catalytic performance, has become an urgent technical problem to be solved in this field. Summary of the Invention
[0005] This invention aims to solve the problem of Zr doping in the existing UiO-66 process. 4+ With Zn 2+ This addresses the defect problem of uncontrollable doping caused by kinetic differences. Furthermore, it provides a method for preparing UiO-66 nanoparticles with a cluster defect structure exhibiting piezoelectric effect.
[0006] A method for preparing UiO-66 nanoparticles with a cluster defect structure exhibiting piezoelectric effect, comprising the following steps:
[0007] I. Material Mixing:
[0008] Hafnium chloride, zirconium chloride, zinc nitrate and terephthalic acid were dissolved in N,N-dimethylformamide solution, then glacial acetic acid was added, and the mixture was sonicated at room temperature to obtain a mixture.
[0009] II. Heating reaction:
[0010] The mixture was heated to react at a temperature of 100℃~150℃, and then cooled to room temperature to obtain the reaction system.
[0011] III. Post-processing:
[0012] The reaction system was centrifuged, the white product was collected, and then washed and dried to obtain UiO-66 nanoparticles with piezoelectric cluster defect structure.
[0013] The beneficial effects of this invention are:
[0014] 1. This invention prepares a trimetallic UiO-66 nanoparticle with uniform size distribution and piezoelectric effect, and successfully forms a catalyst UiO-66 (Zr / Hf / Zn) with artificial cluster defect structure by a one-step solvothermal method.
[0015] 2. By adjusting the ratio of Zr, Hf and Zn, precise control over the particle size and structure of nanoparticles was achieved, with the minimum particle size reaching 160 nm, and Zn was introduced to form artificial cluster defects;
[0016] 3. UiO-66, with an appropriate ratio of hafnium chloride / zirconium chloride / zinc nitrate, possesses an ultra-large specific surface area (888.89 cm²). 3 / g) provided sufficient conditions for the adsorption of reactants;
[0017] 4. Under ultrasonic irradiation, the strong electric field generated within the piezoelectric cluster defect structure of UiO-66 nanoparticles promotes efficient separation of charge carriers, allowing bound charges to be compensated by free space charges, thus achieving continuous enrichment of electrons and holes. Furthermore, oxygen vacancies on the material surface effectively trap electrons, significantly suppressing electron-hole recombination, thereby greatly enhancing the piezoelectric catalytic performance of the material.
[0018] Therefore, the piezoelectric cluster defect structure UiO-66 nanomaterial prepared by this invention has a simple preparation method, uniform size distribution, good catalytic performance, and high electron-hole separation ability. Attached Figure Description
[0019] Figure 1 TEM images of UiO-66 nanoparticles prepared in Example 1 and Comparative Experiments 1 to 5;
[0020] Figure 2 The XRD patterns of UiO-66 nanoparticles prepared in Example 1 and Comparative Experiments 1 to 5 are shown. a is the full spectrum and b is the magnified spectrum at 5°~6.5°.
[0021] Figure 3 Here are the elemental mapping and energy spectrum of reo-UiO-66, where a is the elemental mapping and b is the energy spectrum.
[0022] Figure 4 The N2 adsorption / desorption isotherms of UiO-66 nanoparticles prepared in Example 1 and Comparative Experiments 1 to 5 are shown.
[0023] Figure 5 The UV-vis diffuse reflectance spectra and band diagrams of UiO-66 nanoparticles prepared in Example 1 and Comparative Experiments 1 to 5 are shown. a is the UV-vis diffuse reflectance spectrum and b is the band diagram.
[0024] Figure 6 The images show the valence band spectrum, Mott-Schottky diagram, and band structure of fcu-UiO-66 and reo-UiO-66. a is the valence band spectrum, b is the Mott-Schottky diagram, and c is the band structure diagram.
[0025] Figure 7The in-plane amplitude, amplitude voltage, and phase voltage curves of fcu-UiO-66 and reo-UiO-66 are shown, where a and b are for fcu-UiO-66, and c and d are for reo-UiO-66.
[0026] Figure 8 The results are as follows: a) ESR spectrum of ·OH captured by DMPO (H2O system); b) TEMP capture. 1 ESR spectrum of O2, c represents O2 captured by DMPO (methanol system). ·- ESR spectra;
[0027] Figure 9 The graph shows a comparison of the degradation of MB in the US of UiO-66 nanoparticles prepared in Example 1 and Comparative Experiments 1 to 5. Detailed Implementation
[0028] Specific Implementation Method 1: This implementation method describes a method for preparing UiO-66 nanoparticles with a cluster defect structure exhibiting piezoelectric effect, which is as follows:
[0029] I. Material Mixing:
[0030] Hafnium chloride, zirconium chloride, zinc nitrate and terephthalic acid were dissolved in N,N-dimethylformamide solution, then glacial acetic acid was added, and the mixture was sonicated at room temperature to obtain a mixture.
[0031] II. Heating reaction:
[0032] The mixture was heated to react at a temperature of 100℃~150℃, and then cooled to room temperature to obtain the reaction system.
[0033] III. Post-processing:
[0034] The reaction system was centrifuged, the white product was collected, and then washed and dried to obtain UiO-66 nanoparticles with piezoelectric cluster defect structure.
[0035] The beneficial effects of this embodiment are:
[0036] 1. In this embodiment, a trimetallic UiO-66 nanoparticle with uniform size distribution and piezoelectric effect was prepared, and a catalyst UiO-66 (Zr / Hf / Zn) with artificial cluster defect structure was successfully formed by a one-step solvothermal method.
[0037] 2. By adjusting the ratio of Zr, Hf and Zn, precise control over the particle size and structure of nanoparticles was achieved, with the minimum particle size reaching 160 nm, and Zn was introduced to form artificial cluster defects;
[0038] 3. UiO-66, with an appropriate ratio of hafnium chloride / zirconium chloride / zinc nitrate, possesses an ultra-large specific surface area (888.89 cm²). 3 / g) provided sufficient conditions for the adsorption of reactants;
[0039] 4. Under ultrasonic irradiation, the strong electric field generated within the piezoelectric cluster defect structure of UiO-66 nanoparticles promotes efficient separation of charge carriers, allowing bound charges to be compensated by free space charges, thus achieving continuous enrichment of electrons and holes. Furthermore, oxygen vacancies on the material surface effectively trap electrons, significantly suppressing electron-hole recombination, thereby greatly enhancing the piezoelectric catalytic performance of the material.
[0040] Therefore, the piezoelectric cluster defect structure UiO-66 nanomaterial prepared in this embodiment has a simple preparation method, uniform size distribution, good catalytic performance, and high electron-hole separation ability.
[0041] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the molar ratio of hafnium chloride to zirconium chloride in step one is 1:(1.8~2.2). Everything else is the same as in Specific Implementation Method One.
[0042] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the molar ratio of hafnium chloride to zinc nitrate in step one is 1:(0.8~1.2). Everything else is the same as in Specific Implementation Method One or Two.
[0043] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the molar ratio of hafnium chloride to terephthalic acid in step one is 1:(1~5). Everything else is the same as in Specific Implementation Methods One to Three.
[0044] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the molar ratio of hafnium chloride to the volume ratio of N,N-dimethylformamide solution in step one is 1 mmol:(30~50) mL. Everything else is the same as in Specific Implementation Methods One to Four.
[0045] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the molar ratio of hafnium chloride to glacial acetic acid in step one is 1 mmol:(15~25) mL. Everything else is the same as in Specific Implementation Methods One to Five.
[0046] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that: in step one, the ultrasonic treatment is performed for 0.5 to 2 hours at room temperature and a power of 250W to 400W. Everything else is the same as in Specific Implementation Methods One to Six.
[0047] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: in step two, the mixture is heated and reacted at a temperature of 100℃~150℃ for 12h~20h. Everything else is the same as in Specific Implementation Methods One to Seven.
[0048] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: in step three, the product is centrifuged at a speed of 3000 r / min to 10000 r / min for 5 min to 10 min, the white product is collected, and then washed repeatedly with N,N-dimethylformamide and methanol in sequence. Finally, it is dried at a temperature of 40 to 80°C for 8 h to 12 h. The rest is the same as in Specific Implementation Methods One to Eight.
[0049] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the particle size of the piezoelectric cluster defect structure UiO-66 nanoparticles prepared in step three is 140nm~180nm. Everything else is the same as in Specific Implementation Methods One to Nine.
[0050] The beneficial effects of the present invention are verified using the following embodiments:
[0051] Example 1:
[0052] A method for preparing UiO-66 nanoparticles with a cluster defect structure exhibiting piezoelectric effect, comprising the following steps:
[0053] I. Material Mixing:
[0054] Hafnium chloride, zirconium chloride, zinc nitrate and terephthalic acid were dissolved in N,N-dimethylformamide solution, and then glacial acetic acid was added. The mixture was ultrasonically treated for 1 hour at room temperature and a power of 300W to obtain a mixture.
[0055] The molar ratio of hafnium chloride to zirconium chloride is 0.25:0.5; the molar ratio of hafnium chloride to zinc nitrate is 0.25:0.25; the molar ratio of hafnium chloride to terephthalic acid is 1:3; the molar ratio of hafnium chloride to N,N-dimethylformamide solution is 1 mmol:40 mL; and the molar ratio of hafnium chloride to glacial acetic acid is 1 mmol:20 mL.
[0056] II. Heating reaction:
[0057] The mixture was heated at 120°C for 16 hours and then cooled to room temperature to obtain the reaction system.
[0058] III. Post-processing:
[0059] The reaction system was centrifuged for 5 minutes at a speed of 4500 r / min, and the white product was collected. Then, it was washed repeatedly with N,N-dimethylformamide and methanol in sequence. Finally, it was dried at a temperature of 60℃ for 12 h to obtain UiO-66 nanoparticles, which were named UiO-66(0.5Zr / 0.25Hf / 0.25Zn).
[0060] Comparative Experiment 1: This comparative experiment differs from Example 1 in that the molar ratio of hafnium chloride to zirconium chloride in step 1 is 0.05:0.7; the molar ratio of hafnium chloride to zinc nitrate in step 1 is 0.05:0.25; and the UiO-66 nanoparticles obtained in step 3 are named UiO-66(0.7Zr / 0.05Hf / 0.25Zn). Everything else is the same as in Example 1.
[0061] Comparative Experiment 2: This comparative experiment differs from Example 1 in that the molar ratio of hafnium chloride to zirconium chloride in step 1 is 0.15:0.6; the molar ratio of hafnium chloride to zinc nitrate in step 1 is 0.15:0.25; and the UiO-66 nanoparticles obtained in step 3 are named UiO-66(0.6Zr / 0.15Hf / 0.25Zn). Everything else is the same as in Example 1.
[0062] Comparative Experiment 3: This comparative experiment differs from Example 1 in that the molar ratio of hafnium chloride to zirconium chloride in step 1 is 0.25:0.6; the molar ratio of hafnium chloride to zinc nitrate in step 1 is 0.25:0.15; and the UiO-66 nanoparticles obtained in step 3 are named UiO-66(0.6Zr / 0.25Hf / 0.15Zn). Everything else is the same as in Example 1.
[0063] Comparative Experiment 4: This comparative experiment differs from Example 1 in that the molar ratio of hafnium chloride to zirconium chloride in step 1 is 0.25:0.7; the molar ratio of hafnium chloride to zinc nitrate in step 1 is 0.25:0.05; and the UiO-66 nanoparticles obtained in step 3 are named UiO-66(0.7Zr / 0.25Hf / 0.05Zn). Everything else is the same as in Example 1.
[0064] Comparative Experiment 5: This comparative experiment differs from Example 1 in that the molar ratio of hafnium chloride to zirconium chloride in step 1 is 0.25:0.75; the UiO-66 nanoparticles obtained in step 3 are named UiO-66(0.75Zr / 0.25Hf). Everything else is the same as in Example 1.
[0065] Figure 1The images show TEM images of the UiO-66 nanoparticles prepared in Example 1 and Comparative Experiments 1 to 5. As can be seen from the images, in the binary metal system containing only Zr and Hf, the particle size of UiO-66 is 2μm to 3μm. It is noteworthy that when Zn is introduced, and the Zn content increases to 0.25%, the average particle size of the UiO-66 samples gradually decreases from UiO-66 (0.75Zr / 0.25Hf), UiO-66 (0.7Zr / 0.25Hf / 0.05Zn), UiO-66 (0.6Zr / 0.25Hf / 0.15Zn) to UiO-66 (0.5Zr / 0.25Hf / 0.25Zn). When the molar ratio is adjusted to 0.5:0.25:0.25, the crystal size of UiO-66 (0.5Zr / 0.25Hf / 0.25Zn) decreases to approximately 160 nm, with a uniform morphology. This series of data fully confirms that the incorporation of Zn has a significant regulatory effect on the grain growth kinetics of the material. However, when the relative content of Hf in the system decreases below a certain threshold, the three-dimensional topological structure of the reo-UiO-66 framework exhibits significant stability degradation, specifically manifested as the irreversible collapse of the crystal framework and its transformation into irregular nanoparticles. This reveals that Hf plays an irreplaceable role in maintaining the structural stability of the trimetallic UiO-66 framework, and its appropriate content control is a key parameter for achieving the preparation of high-quality defect-engineered reo-UiO-66 materials.
[0066] Figure 2 The XRD patterns of UiO-66 nanoparticles prepared in Example 1 and Comparative Experiments 1 to 5 are shown in Figure 1. a is the full spectrum, and b is a magnified spectrum at 5°–6.5°. As can be seen from the figure, the UiO-66 frameworks composed of different proportions of metal elements all possess typical UiO-66 XRD patterns. Magnification at 5°–6.5° reveals the typical (110) characteristic peak of the reo topology in the UiO-66 spectrum containing Zr, Hf, and Zn in a ratio of 0.5:0.25:0.25. The sample exhibits significant diffraction at 6°, rather than broad diffraction in that region, demonstrating that the reo nanoregions are uniformly distributed and have a long-range order, and that the structure is close to the reo topology. The other UiO-66 spectra did not show the typical (110) characteristic peak, therefore their structures are fcu topologies.
[0067] The UiO-66 (0.5Zr / 0.25Hf / 0.25Zn) reo topology with missing cluster defects is named reo-UiO-66, and the UiO-66 (0.75Zr / 0.25Hf) normal fcu topology without defects is abbreviated as fcu-UiO-66.
[0068] Figure 3The figure shows the elemental mapping and energy spectrum of reo-UiO-66, with a being the elemental mapping and b being the energy spectrum. As can be seen from the figure, Zn ions are uniformly distributed in the mixed metal MOFs, and EDS confirms that Zr, Hf and Zn are uniformly dispersed.
[0069] Figure 4 The N2 adsorption / desorption isotherms are shown for the UiO-66 nanoparticles prepared in Example 1 and Comparative Experiments 1 to 5. Analysis of three UiO-66 samples (0.7Zr / 0.25Hf / 0.05Zn), (0.6Zr / 0.25Hf / 0.15Zn), and (0.5Zr / 0.25Hf / 0.25Zn) revealed that the micropore volume gradually increased from 340.5 cm³ to [the desired Zn content]. 3 / g increased to 888.89cm 3 / g, the isotherm curve corresponds to a type I isotherm, mainly indicating adsorption through micropores, proving that the outer surface area of the sample is much smaller than the inner surface area of the pores, and the adsorption capacity is controlled by the pore volume. Analysis of three UiO-66 samples—UiO-66(0.75Zr / 0.25Hf), UiO-66(0.7Zr / 0.05Hf / 0.25Zn), and UiO-66(0.6Zr / 0.15Hf / 0.25Zn)—shows that reducing the Zr element ratio transforms the isotherm curve into a type II isotherm, further demonstrating that the UiO-66 framework is disrupted, and that UiO-66(0.5Zr / 0.25Hf / 0.25Zn) is the optimal doping ratio.
[0070] Figure 5 The UV-vis diffuse reflectance spectra and band structures of UiO-66 nanoparticles prepared in Example 1 and Comparative Experiments 1 to 5 are shown. a is the UV-vis diffuse reflectance spectrum, and b is the band structure diagram. The band structure of UiO-66 with different metal contents was measured using UV-vis diffuse reflectance spectroscopy, and the results were plotted by (αhv). 2 The band gap energy can be calculated from the relationship with the absorbed light energy, among which the UiO-66 (0.5Zr / 0.25Hf / 0.25Zn) with reo topology has the smallest band gap (3.00eV).
[0071] Figure 6Figures a, b, and c show the valence band structure, Mott-Schottky diagram, and energy band structure of fcu-UiO-66 and reo-UiO-66, respectively. Figure a shows the valence band structure, b shows the Mott-Schottky diagram, and c shows the energy band structure. Figure a shows the band gap widths of fcu-UiO-66 and reo-UiO-66, which are 2.69 eV and 2.48 eV, respectively. Figure b shows that the slopes of the Mott-Schottky curves for both fcu-UiO-66 and reo-UiO-66 are positive, a typical characteristic of n-type semiconductors. The flat band potentials E of fcu-UiO-66 and reo-UiO-66 relative to the Ag / AgCl electrode are also shown. fb (vs Ag / AgCl) were -0.96 eV and -1.18 eV, respectively. Then, via E... fb (vs NHE)=E fb (vs Ag / AgCl)+E Ag / AgCl The flat-band potential E relative to the standard hydrogen electrode was calculated from +0.059 pH. fb (vs NHE) are -0.35 eV and -0.57 eV, respectively. Generally, the conduction band position of an n-type semiconductor is approximately equal to the flat band potential relative to a standard hydrogen electrode. Therefore, combining the band gap width, the valence band potentials of fcu-UiO-66 and reo-UiO-66 are calculated to be 2.34 eV and 1.91 eV, respectively. Based on the above data, the band structure of the nanosheets is constructed, and the underlying mechanism is finally proposed and elucidated. Figure 6 c). As shown in Figure c, the CB edge ratio of reo-UiO-66 is O2 / O2. ·- The redox potential (-0.33V) is slightly positive, and its VB edge is also higher than that of OH. - The redox potential (1.99V) of OH is corrected, but given its excellent piezoelectric properties, reo-UiO-66 is expected to generate a variety of ROS.
[0072] Figure 7 The figures show the in-plane amplitude, amplitude voltage, and phase voltage curves of fcu-UiO-66 and reo-UiO-66, where a and b represent fcu-UiO-66, and c and d represent reo-UiO-66. As can be seen from the figures, both solid fcu-UiO-66 and reo-UiO-66 exhibit piezoelectricity. The d-phase voltage curve of reo-UiO-66... 33 Reached 27:56 pm V -1 It was significantly higher than fcu-UiO-66 (16.08 pm V). -1 ).
[0073] To confirm the type of ROS generated during piezoelectric catalysis, ESR analysis was performed, using TEMP as a chromatogram. 1 O2 scavenger, and DMPO as a ·OH and O2 scavenger. ·-The trapping agent; the specific parameters of US are as follows: 1MHz, 50% duty cycle, 0.96W cm⁻¹ -2 ; Figure 8 The results are as follows: a) ESR spectrum of ·OH captured by DMPO (H2O system); b) TEMP capture. 1 ESR spectrum of O2, c represents O2 captured by DMPO (methanol system). ·- The ESR spectra of the fcu-UiO-66+US and reo-UiO-66+US groups (1 MHz, 50% duty cycle, 0.96 W / cm²) are shown in the figure. -2 ) observed corresponding to 1 O2, ·OH and O2 ·- Characteristic peaks. Notably, the peak detected in the reo-UiO-66+US group was significantly larger than that in the fcu-UiO-66+US group, while no significant characteristic peaks were observed in the US group and the trapping agent + US group.
[0074] Figure 9 This is a comparison graph showing the degradation of MB by UiO-66 nanoparticles prepared in Example 1 and Comparative Experiments 1 to 5 in US. The degradation was achieved in US (1 MHz, 50% duty cycle, 0.96 W / cm²). -2 At the following concentrations, MB (1 mg / mL) was used. -1 The degradation of ·OH by reo-UiO-66 was used as an indicator of ·OH generation to evaluate the piezoelectric effect. This method is based on the ability of ·OH to react with MB and convert it into a colorless byproduct. Under prolonged ultrasonic irradiation, the intensity of the characteristic absorption peak of MB at 665 nm gradually decreased. Comparative analysis showed that, compared with different metal ratios of UiO-66, reo-UiO-66 (0.5Zr / 0.25Hf / 0.25Zn) exhibited the fastest degradation rate of MB. That is, the ·OH generation efficiency of reo-UiO-66 (0.5Zr / 0.25Hf / 0.25Zn) was superior to other metal ratios, indicating that the formation of cluster defects significantly enhanced carrier separation and increased the generation of ·OH through the interaction of H2O with holes, thereby improving the piezoelectric catalytic effect. Specifically, the intensity of the characteristic absorption peak of MB at 665 nm decreased by 62.8% in the reo-UiO-66 (0.5Zr / 0.25Hf / 0.25Zn) group, while it decreased by 41.5% in the fcu-UiO-66 (0.75Zr / 0.25Hf) group.
Claims
1. A method for preparing UiO-66 nanoparticles with a cluster defect structure exhibiting piezoelectric effect, characterized in that... It is done in the following steps: I. Material Mixing: Hafnium chloride, zirconium chloride, zinc nitrate and terephthalic acid were dissolved in N,N-dimethylformamide solution, then glacial acetic acid was added, and the mixture was sonicated at room temperature to obtain a mixture. II. Heating reaction: The mixture was heated to react at a temperature of 100℃~150℃, and then cooled to room temperature to obtain the reaction system. III. Post-processing: The reaction system was centrifuged, the white product was collected, and then washed and dried to obtain UiO-66 nanoparticles with piezoelectric cluster defect structure.
2. The method for preparing UiO-66 nanoparticles with piezoelectric cluster defect structure according to claim 1, characterized in that... The molar ratio of hafnium chloride to zirconium chloride mentioned in step one is 1:(1.8~2.2).
3. The method for preparing UiO-66 nanoparticles with piezoelectric cluster defect structure according to claim 1, characterized in that... The molar ratio of hafnium chloride to zinc nitrate mentioned in step one is 1:(0.8~1.2).
4. The method for preparing UiO-66 nanoparticles with piezoelectric cluster defect structure according to claim 1, characterized in that... The molar ratio of hafnium chloride to terephthalic acid mentioned in step one is 1:(1~5).
5. The method for preparing UiO-66 nanoparticles with piezoelectric cluster defect structure according to claim 1, characterized in that... The molar ratio of hafnium chloride to N,N-dimethylformamide solution in step one is 1 mmol:(30~50) mL.
6. The method for preparing UiO-66 nanoparticles with piezoelectric cluster defect structure according to claim 1, characterized in that... The molar ratio of hafnium chloride to glacial acetic acid in step one is 1 mmol: (15~25) mL.
7. The method for preparing UiO-66 nanoparticles with piezoelectric cluster defect structure according to claim 1, characterized in that... In step one, the ultrasonic treatment is carried out for 0.5h to 2h at room temperature and power of 250W~400W.
8. The method for preparing UiO-66 nanoparticles with piezoelectric cluster defect structure according to claim 1, characterized in that... In step two, the mixture is heated and reacted at a temperature of 100℃~150℃ for 12h~20h.
9. The method for preparing UiO-66 nanoparticles with piezoelectric cluster defect structure according to claim 1, characterized in that... In step three, the product is centrifuged at a speed of 3000 r / min to 10000 r / min for 5 min to 10 min, and the white product is collected. Then, it is washed repeatedly with N,N-dimethylformamide and methanol in sequence, and finally dried at a temperature of 40 to 80℃ for 8 h to 12 h.
10. The method for preparing UiO-66 nanoparticles with piezoelectric cluster defect structure according to claim 1, characterized in that... The piezoelectric cluster defect structure UiO-66 nanoparticles prepared in step three have a particle size of 140 nm to 180 nm.