A CoO / Bi2SiO5 piezoelectric photocatalyst, its preparation method, and its application.
Patent Information
- Application Number
- CN202610795331.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-03
- Publication Date
- 2026-09-25
AI Technical Summary
[0005]单一的铋硅酸盐虽具有压电光催化特性，但其催化性能存在一定局限
[0018]本发明制备得到的ZIF-67衍生物掺杂Bi2SiO5的压电光催化剂大小均一，具有良好的压电光催化性能，同时保留了硅酸铋及ZIF-67有的特性，拥有较高的稳定性；重复使用性强，可用于压电光催化废水处理行业中处理有毒有害废水。
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of piezoelectric photocatalysis, and is a composite piezoelectric photocatalyst for treating organic pollutants in wastewater, its preparation method, and its application. Background Technology
[0002] Piezoelectric photocatalysis is an effective method for degrading organic pollutants. When stimulated by mechanical stress and light energy, piezoelectric photocatalysts can generate charges to directly participate in the reaction; simultaneously, a polarized electric field is formed inside the material, forcing electrons (activated in the conduction band) and holes (activated in the valence band) to move in opposite directions. Therefore, electron-hole pairs achieve effective spatial separation and can subsequently participate in the catalytic reaction.
[0003] Three-dimensional flower-like Bi₂SiO₅ has attracted much attention due to its unique layered structure, large specific surface area, ease of separation, good stability, and ability to facilitate the movement of photogenerated holes, thus improving photocatalytic activity. Furthermore, it possesses an excellent piezoelectric coefficient (Di). 33 Bi2SiO5 has been developed into a novel piezoelectric photocatalyst with its band gap energy (Eg). The prepared material has a suitable band potential for generating reactive oxygen species (ROS) and has broad application prospects in the field of piezoelectric photocatalysis. At present, people have made extensive research and application of it by taking advantage of the advantages of Bi2SiO5.
[0004] The ZIF series is a subclass of MOFs, and ZIF-67 is a typical cobalt-based MOF, prepared by reacting cobalt ions with 2-methylimidazole. Using ZIF-67 as a precursor, annealing was performed to directly synthesize nanocubes with a novel hollow structure. Since the reduction of cobalt ions to cobalt atoms continues to catalyze graphitization of surrounding carbon, the degree of graphitization and specific surface area of the catalyst can be significantly altered, resulting in a sufficient specific surface area for rapid diffusion of electrolytes and ions. Furthermore, the high specific surface area and controllable pore array structure of ZIF-67 are retained, leading to a more efficient oxidation catalyst.
[0005] While bismuth silicates possess piezoelectric photocatalytic properties, their catalytic performance is somewhat limited. Further in-depth research is needed to achieve effective carrier separation and obtain sufficient reaction sites in semiconductor catalysts. In the field of catalysis, ZIF-67 derivatives, due to their porous structure and high specific surface area, can improve the utilization rate of incident light and shorten the carrier migration distance, thus providing additional surface sites for the photodegradation process of catalysts.
[0006] This invention first uses ZIF-67 as a precursor to anneal to obtain ZIF-67 derivatives, and then prepares a catalyst doped with Bi2SiO5 by solvothermal method and one-pot method to obtain a composite piezoelectric photocatalyst. Summary of the Invention
[0007] This invention uses ZIF-67 as a precursor, converts ZIF-67 into CoO through an annealing process, and then does the prepared ZIF-67 derivative with Bi2SiO5 through a solvothermal method and a one-pot method to obtain a composite piezoelectric photocatalyst with strong stability, good photoelectrocatalytic performance, and safety and non-toxicity. The composite piezoelectric photocatalyst is then applied to the degradation of wastewater.
[0008] To achieve the above objectives, the present invention provides the following solution:
[0009] (1) Preparation of ZIF-67 derivative CoO: Co(NO3)2·6H2O and 2-methylimidazole were dissolved in methanol, respectively, and sonicated to form solutions A and B. Solution A was then poured into solution B to obtain a purple ZIF-67 precursor solution. After stirring, the solution was reacted at room temperature for 12 h. The purple precipitate was collected by filtration, washed several times with methanol, and finally dried under vacuum at 80 °C for 6 h. The ZIF-67 precursor was then dried in air at 5 °C·min. -1 The heating rate was increased to 600℃ and calcined for 2 hours to obtain the ZIF-67 derivative CoO generated from the ZIF-67 precursor.
[0010] (2) Preparation of ZIF-67 derivative-doped Bi2SiO5 catalyst: 4.8 mmol Bi(NO3)3·5H2O was ultrasonically dissolved in 40 mL glycerol to form solution A, and 2.4 mmol Na2SiO3·9H2O and the ZIF-67 derivative CoO prepared in step (1) were dissolved in 12.0 mL ammonia water (1:10) to form solution B. Solution B was added dropwise to solution A, and the pH of the mixed solution was approximately 9.0. After stirring the mixed solution for 30 minutes, it was poured into a hydrothermal reactor and solvated at 180℃ for 24 hours. The sample was filtered, washed three times with deionized water and anhydrous ethanol, and then dried in a vacuum drying oven at 60℃ for 6 hours. The final sample obtained was the ZIF-67 derivative-doped Bi2SiO5 catalyst.
[0011] 1. Preferred: The molar ratio of Co(NO3)2·6H2O and 2-methylimidazole in step (1) is 1:4.
[0012] 2. Preferably, the reaction temperature of the ZIF-67 precursor solution in step (1) is room temperature.
[0013] 3. Specifically: The ZIF-67 precursor described in step (1) is calcined at 600°C for 2 hours in an air atmosphere.
[0014] 4. Preferably, the molar ratio of the ZIF-67 derivative and Bi2 (nitrate)3·5H2O in step (2) is 1:15.
[0015] 5. Preferably, the pH value of the mixed solution in step (2) is about 9.0.
[0016] 6. Specifically: The heating temperature in step (2) is 180℃.
[0017] 7. Specifically: The heating reaction time in step (3) is 24 hours.
[0018] The ZIF-67 derivative-doped Bi2SiO5 piezoelectric photocatalyst prepared by this invention has uniform size and good piezoelectric photocatalytic performance. At the same time, it retains the characteristics of bismuth silicate and ZIF-67, and has high stability. It is highly reusable and can be used in the piezoelectric photocatalytic wastewater treatment industry to treat toxic and harmful wastewater. Attached Figure Description
[0019] Figure 1 The effect of ZIF-67 derivative-doped Bi2SiO5 piezoelectric photocatalyst on the degradation of 4-chlorophenol;
[0020] Figure 2 The effect of ZIF-67 derivative-doped Bi2SiO5 piezoelectric photocatalyst on the degradation of 4-chlorophenol;
[0021] Figure 3 XRD pattern of the piezoelectric photocatalyst doped with Bi2SiO5 and ZIF-67 derivative;
[0022] Figure 4 The UV-Vis diffuse reflectance spectrum of the piezoelectric photocatalyst doped with Bi2SiO5 and ZIF-67 derivative; Detailed Implementation
[0023] The present invention will be further described below with reference to examples:
[0024] Example 1
[0025] A method for preparing a CoO / Bi2SiO5 piezoelectric photocatalyst includes the following steps:
[0026] 1) Preparation of ZIF-67 derivative CoO: Co(NO3)2·6H2O and 2-methylimidazole were first dissolved in methanol, and after sonication, solutions A and B were formed. Solution A was then poured into solution B to obtain a purple ZIF-67 precursor solution. After stirring, the solution was reacted at room temperature for 12 h. The purple precipitate was collected by filtration, washed several times with methanol, and finally dried under vacuum at 80 °C for 6 h. The ZIF-67 precursor was then dried in air at 5 °C·min.-1 The heating rate was increased to 600℃ and calcined for 2 hours to obtain the ZIF-67 derivative CoO generated from the ZIF-67 precursor.
[0027] (2) Preparation of ZIF-67 derivative-doped Bi2SiO5 catalyst: 4.8 mmol Bi(NO3)3·5H2O was ultrasonically dissolved in 40 mL glycerol to form solution A, and 2.4 mmol Na2SiO3·9H2O and the ZIF-67 derivative CoO prepared in step (1) were dissolved in 12.0 mL ammonia water (1:10) to form solution B. Solution B was added dropwise to solution A, and the pH of the mixed solution was approximately 9.0. After stirring the mixed solution for 30 minutes, it was poured into a hydrothermal reactor and solvated at 180℃ for 24 hours. The sample was filtered, washed three times with deionized water and anhydrous ethanol, and then dried in a vacuum drying oven at 60℃ for 6 hours. The final sample obtained was the ZIF-67 derivative-doped Bi2SiO5 catalyst.
[0028] Example 2
[0029] The difference from Example 1 is that the calcination temperature in step (1) is 400℃, 500℃, 700℃, and 800℃, while the other parameters and operating steps are the same.
[0030] Example 3
[0031] The difference from Example 1 is that the molar ratio of ZIF-67 derivative to Bi(NO3)3·5H2O in step (2) is 1:5, 1:10, 1:20, and 1:25, while the other parameters and operating steps are the same.
[0032] Example 4
[0033] The difference from Example 1 is that the pH value of the mixed solution in step (2) is approximately 8.0, 9.0, 10.0, and 11.0, while the other parameters and operating steps are the same.
[0034] Example 5
[0035] The difference from Example 1 is that the heating temperature in step (2) is 160°C, 200°C, and 220°C, while the other parameters and operating steps are the same.
[0036] Example 6
[0037] The difference from Example 1 is that the heating reaction time in step (3) is 12h, 16h, and 20h, while the other parameters and operating steps are the same.
[0038] The ZIF-67 derivative-doped Bi₂SiO₅ piezoelectric photocatalysts prepared in Examples 1-6 above were tested and analyzed. The reagents and instruments used in the experiments are as follows:
[0039] Bismuth nitrate pentahydrate (Bi(NO3)3·5H2O): Shanghai Maclean Biochemical Technology Co., Ltd.; Sodium silicate nonahydrate (Na2SiO3·9H2O): Xilong Chemical Co., Ltd.; Cobalt nitrate hexahydrate (Co(NO3)2·6H2O): Shanghai Maclean Biochemical Technology Co., Ltd.; 2-Methylimidazole: Sinopharm Chemical Reagent Co., Ltd.; Ammonia water: Sinopharm Chemical Reagent Co., Ltd.; Methanol: Sinopharm Chemical Reagent Co., Ltd.; Anhydrous ethanol: Sinopharm Chemical Reagent Co., Ltd.; All the above reagents were of analytical grade. High performance liquid chromatograph: Agilent Technologies; X-ray diffractometer: Rigaku miniflex600 (Japan); UV-Vis-DRS: RG5000J.
[0040] Analysis of the piezoelectric photocatalyst effect and structure of ZIF-67 derivative doped with Bi2SiO5:
[0041] 1. Effect of the molar ratio of CoO to Bi(NO3)3·5H2O on the degradation of 4-chlorophenol by piezoelectric photocatalyst
[0042] Following the method described in Example 1, a piezoelectric photocatalyst doped with Bi₂SiO₅ and ZIF-67 derivatives was prepared. Na₂SiO₃·9H₂O was dissolved in 12.0 mL of ammonia (1:10), and ZIF-67 derivative CoO was added at molar ratios of 1:5, 1:10, 1:15, 1:20, and 1:25, respectively. This solution was then added dropwise to a Bi(NO₃)₃·5H₂O solution. After stirring the mixture for 30 minutes, it was poured into a hydrothermal reactor and solvated at 180℃ for 24 hours. The sample was filtered, washed three times with deionized water and anhydrous ethanol, and then dried in a vacuum drying oven at 60℃ for 6 hours. The final sample obtained was the ZIF-67 derivative CoO-doped Bi₂SiO₅ catalyst CoO / Bi₂SiO₅. The removal rate of 4-chlorophenol at 150 min was used as the evaluation index to investigate the removal effect of different concentrations of ZIF-67 derivatives on 4-chlorophenol. The degradation conditions were as follows: 100 mL of 4-chlorophenol at an initial concentration of 10 mg / L, catalyst concentration of 1 g / L. The piezoelectric photocatalytic experiment was conducted in an ultrasonic cleaner using a 300 W xenon lamp light source. After the test, the degradation rate of 4-CP by the photoanode was calculated using the following formula: (initial 4-CP concentration - 4-CP concentration at 150 minutes) / initial 4-CP concentration. Figure 1It can be seen that under the condition of a reaction time of 150 min, the ZIF-67 derivative reacts with Bi(NO3)3 · The degradation effect was best when the molar ratio of 5H2O was 1:15, with a degradation efficiency of 78.90%.
[0043] 2. Determination of the piezoelectric photocatalytic degradation effects of Bi2SiO5, CoO, and CoO / Bi2SiO5
[0044] Depend on Figure 2 It can be seen that the degradation effect was improved after Bi2SiO5 was supported by CoO. After 150 min of reaction, the degradation rate of 4-CP increased from 48.50% to 78.90%, an increase of 30.4%. This is because the doping of CoO promotes the light absorption rate of the catalyst surface, increases the specific surface area of the catalyst, provides more reactive sites, and facilitates the rapid diffusion of ions, thereby improving the catalytic efficiency for 4-CP.
[0045] 3. X-ray diffraction (XRD) analysis of the crystal structures of Bi2SiO5, CoO, and CoO / Bi2SiO5 photoelectrodes.
[0046] Figure 3 The XRD patterns of Bi2SiO5, CoO, and CoO / Bi2SiO5 are shown. The Bi2SiO5 sample exhibits diffraction peaks at 23.89°, 29.34°, and 32.82°, corresponding to the (310), (311), and (510) crystal planes of the Bi2SiO5 standard PDF, respectively. This result indicates that Bi2SiO5 crystals were successfully synthesized in the laboratory using a one-pot method, and the diffraction peaks all exhibit strong and sharp characteristics, indicating that the obtained Bi2SiO5 has good crystallinity. The CoO sample shows four distinct diffraction peaks at 36.49°, 42.38°, 61.49°, and 73.67°, which can be attributed to the (111), (200), (220), and (311) crystal planes of cobalt oxide, respectively. This result indicates that CoO was synthesized in the laboratory from the ZIF-67 precursor through an annealing process. In addition, the CoO / Bi2SiO5 composite sample was also characterized by XRD. Figure 2 As can be seen, the composite sample still conforms to the characteristic peak shape of typical Bi2SiO5 and CoO. Based on the above results, the experiment successfully prepared a CoO / Bi2SiO5 composite piezoelectric photocatalyst with good crystallinity, and no other impurities appeared in the sample. The prepared catalyst has high purity.
[0047] 4. UV-Vis diffuse reflectance spectra of Bi2SiO5 and CoO / Bi2SiO5
[0048] Figure 4The results show that CoO doping of Bi₂SiO₅ in the ZIF-67 derivative increases the specific surface area of CoO / Bi₂SiO₅, thereby improving the absorbance in the visible light region. The absorbance intensity of the CoO / Bi₂SiO₅ piezoelectric photocatalyst in the visible light region is significantly improved, which may be due to the fact that doping promotes electron transfer and the separation rate of photogenerated carriers.
[0049] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.
Claims
1. A method for preparing a CoO / Bi2SiO5 piezoelectric photocatalyst and its application, characterized in that: Includes the following steps: (1) Preparation of ZIF-67 derivative CoO: Co(NO3)2·6H2O and 2-methylimidazole were dissolved in methanol, respectively, and sonicated to form solutions A and B. Solution A was then poured into solution B to obtain a purple ZIF-67 precursor solution. After stirring, the solution was reacted at room temperature for 12 h. The purple precipitate was collected by filtration, washed several times with methanol, and finally dried under vacuum at 80 °C for 6 h. The ZIF-67 precursor was then subjected to an air atmosphere at 5 °C·min. -- The heating rate was increased to 600℃ and calcined for 2 hours to obtain the ZIF-67 derivative CoO generated from the ZIF-67 precursor. (2) Preparation of ZIF-67 derivative-doped Bi2SiO5 catalyst: 4.8 mmol Bi(NO3)3·5H2O was ultrasonically dissolved in 40 mL glycerol to form solution A. 2.4 mmol Na2SiO3·9H2O and the ZIF-67 derivative CoO prepared in step (1) were dissolved in 12.0 mL ammonia water (1:10) to form solution B. Solution B was added dropwise to solution A. The pH of the mixed solution was about 9.
0. After stirring the mixed solution for 30 minutes, it was poured into a hydrothermal reactor and solvothermal treated at 180℃ for 24 hours. The sample was filtered and washed three times with deionized water and anhydrous ethanol, and then dried in a vacuum drying oven at 60℃ for 6 hours. The final sample was the ZIF-67 derivative-doped Bi2SiO5 catalyst.
2. The CoO / Bi2SiO5 piezoelectric photocatalyst and its preparation method according to claim 1, characterized in that: The molar ratio of Co(NO3)2·6H2O and 2-methylimidazole in step (1) is 1:
4.
3. The CoO / Bi2SiO5 piezoelectric photocatalyst and its preparation method according to claim 1, characterized in that: The reaction temperature of the ZIF-67 precursor solution in step (1) is room temperature.
4. The CoO / Bi2SiO5 piezoelectric photocatalyst and its preparation method according to claim 1, characterized in that: The ZIF-67 precursor described in step (1) is calcined at 600°C for 2 hours in an air atmosphere.
5. The CoO / Bi2SiO5 piezoelectric photocatalyst and its preparation method according to claim 1, characterized in that: The molar ratio of the ZIF-67 derivative to Bi(NO3)3·5H2O in step (2) is 1:
15.
6. The CoO / Bi2SiO5 piezoelectric photocatalyst and its preparation method according to claim 1, characterized in that: The pH value of the mixed solution described in step (2) is approximately 9.
0.
7. The CoO / Bi2SiO5 piezoelectric photocatalyst and its preparation method according to claim 1, characterized in that: The heating temperature in step (2) is 180°C.
8. The CoO / Bi2SiO5 piezoelectric photocatalyst and its preparation method according to claim 1, characterized in that: The heating reaction time in step (2) is 24 hours.
9. A CoO / Bi2SiO5 piezoelectric photocatalyst and its preparation method according to any one of claims 1 to 8, characterized in that: The prepared CoO / Bi2SiO5 piezoelectric photocatalyst was used for the treatment of organic pollutants in wastewater under photo-piezoelectric conditions.