A metal-modified covalent organic framework material and its preparation method and application

Abstract

The present invention discloses a metal-modified covalent organic framework material and its preparation method and application, which belong to the field of piezoelectric catalysis technology. The metal-modified covalent organic framework material of the present invention is synthesized by 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol as precursors, and is obtained after metal post-modification, wherein the metal includes one or more of antimony, molybdenum, chromium, calcium, magnesium, manganese, and barium. The metal-modified covalent organic framework M-TfpBpy-COF of the present invention can produce charge offset after deformation when stimulated by mechanical vibration, and water oxidation and oxygen reduction reaction occur simultaneously at the active center on the surface of the material to generate hydrogen peroxide. The adjustability and selectivity of the covalent organic framework structure provide rich sites for metal loading, thereby preparing an excellent piezoelectric catalytic active material.

Description

Technical Field

[0001] The present invention relates to the field of piezoelectric catalysis technology, and more specifically, to a metal-modified covalent organic framework material, a preparation method thereof, and an application thereof. Background Art

[0002] Hydrogen peroxide (H2O2), an important inorganic chemical, is a green, clean, and renewable energy source widely used in environmental management and energy applications, including corrosion protection, bleaching, and chemical synthesis. Traditionally, industrial hydrogen peroxide is produced via the anthraquinone process, which accounts for 95% of global industrial hydrogen peroxide production. However, this method involves complex process flows, consumes a lot of energy, and produces toxic byproducts, making it environmentally unfriendly. Therefore, finding efficient, economical, environmentally friendly, and mild hydrogen peroxide production methods is an urgent challenge. Covalent organic frameworks (COFs) are crystalline porous materials with periodic structures composed of organic building blocks composed of lightweight elements such as carbon, hydrogen, oxygen, and nitrogen, connected by strong covalent bonds. They possess advantages such as low density, strong stability, a rich, ordered pore structure, and a large specific surface area. The designability and selectivity of COFs' building blocks allow the introduction of diverse functional active centers through coordination within precisely designed building blocks, greatly enriching their application prospects as catalysts. Mechanical energy, a ubiquitous energy source in the human environment, is more abundant and stable than solar energy, thermal energy, and electrical energy. Natural motions such as wind, rain, and water flow; bodily movements such as heartbeats, breathing, and muscle contractions; and the sounds common in densely populated cities all generate mechanical energy. Among these, the various sounds generated by human activities, such as industrial production, traffic, and entertainment venues, which are considered noise pollution, can also generate vibrational energy. The mechanical stress generated by these vibrations can cause certain non-centrosymmetric solid materials to respond, accumulating charge along the polarization direction of the crystal. Materials that can convert mechanical stimuli into electrical signals are called piezoelectric materials. Piezoelectric materials include piezoelectric single crystals, polycrystalline piezoelectric ceramics, polymer piezoelectric materials, and polymer-piezoelectric ceramic composites. Currently, their applications are primarily in cavity oscillators, piezoelectric transducers, and biomaterials, but their scope is relatively narrow. However, efforts to construct COFs with piezoelectric catalytic properties by designing stacking units to efficiently produce hydrogen peroxide using mechanical energy to reduce oxygen molecules and oxidize water molecules have yet to be explored.

[0003] The prior art discloses a carbon nanotube material derived from a covalent organic framework and a preparation method thereof, which provides a solution for how to improve the specific surface area and morphology regularity and controllability of the carbon material derived from COFs to optimize performance. The preparation method of the material includes the following steps:

[0004] (1) Metal nanowires were selected as templates, and COFs were grown in situ on their surfaces via a solvothermal reaction under vacuum to obtain composite materials;

[0005] (2) placing the composite material obtained in step (1) in a reaction vessel, heating it to 800-1000° C., and then cooling it to obtain a carbonized material; wherein the entire process is under the protection of an inert gas;

[0006] (3) The carbonized material obtained in step (2) is placed in a container for acid washing, and then filtered, washed, and dried to obtain a COFs-derived carbon nanotube material.

[0007] This material mainly improves the performance of COFs-derived carbon nanotube materials in catalytic cathode oxygen reduction, increasing the limiting current density and half-wave potential, but does not have excellent piezoelectric catalytic performance. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of poor chemical stability of existing covalently modified organic framework materials COFs, and provide a metal-modified covalent organic framework material. By modifying different metals on TfpBpy-COF, a metal-modified covalent organic framework M-TfpBpy-COF with piezoelectricity is constructed. The metal-modified COF exhibits excellent piezoelectric catalytic performance and can be used in the piezoelectric catalytic preparation of hydrogen peroxide with good catalytic activity.

[0009] Another object of the present invention is to provide a method for preparing a metal-modified covalent organic framework material.

[0010] Another object of the present invention is to provide an application of a metal-modified covalent organic framework material in the piezoelectric catalytic preparation of hydrogen peroxide.

[0011] Another object of the present invention is to protect a method for preparing hydrogen peroxide by piezoelectric catalysis.

[0012] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0013] A metal-modified covalent organic framework material is synthesized using 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol as precursors, and then metal is modified on the synthesized covalent organic framework to obtain the metal-modified covalent organic framework material M-TfpBpy-COF.

[0014] The metal includes one or more of antimony, molybdenum, chromium, calcium, magnesium, manganese and barium.

[0015] Among them, it should be noted that:

[0016] The metal-modified covalent organic framework material of the present invention still has excellent chemical stability after metal modification. XRD before and after modification shows that its crystallinity has not changed, and SEM images show that there is no change before and after modification, thus retaining the excellent chemical stability of COF.

[0017] The metal-modified covalent organic framework material of the present invention can be any one of Sb-TfpBpy-COF, Mo-TfpBpy-COF, Cr-TfpBpy-COF, Ca-TfpBpy-COF, Mg-TfpBpy-COF, Mn-TfpBpy-COF, and Ba-TfpBpy-COF.

[0018] Because the metal-modified covalent organic framework changes the symmetry within the framework, a piezoelectric effect is generated under ultrasonic driving, and the separated positive and negative charges undergo oxygen reduction and water oxidation reactions.

[0019] The piezoelectric metal-modified covalent organic framework material of the present invention, when stimulated by mechanical vibration, generates mechanical force generated by ultrasound to deform the framework structure. Electrons are generated and deflected after deformation, and separated positive and negative charges accumulate in the active center. The modification changes the charge transfer and exhibits excellent piezoelectric catalytic performance. The material has a large specific surface area and a large number of pores. The abundant active sites can fully carry out catalytic reactions. At the same time, the material has good stability in water and can continuously and efficiently generate hydrogen peroxide. It can still produce hydrogen peroxide after recycling and can be recycled. It has broad application prospects.

[0020] The present invention further specifically protects a method for preparing a metal-modified covalent organic framework material, comprising the following steps:

[0021] S1. 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol were used to synthesize TfpBpy-COF containing bipyridine groups via a solvothermal method catalyzed by acetic acid;

[0022] S2. The TfpBpy-COF prepared in S1 and metal compounds containing antimony, molybdenum, chromium, calcium, magnesium, manganese, and barium are added to an organic solution, heated for reaction, washed, and vacuum dried to obtain a metal-modified covalent organic framework M-TfpBpy-COF.

[0023] Preferably, the mass ratio of the metal compound to TfpBpy-COF is 1:0.8-2.5.

[0024] More preferably, the mass ratio of the metal compound to TfpBpy-COF is 1:1-2.

[0025] The catalytic performance of the synthesized materials varies depending on the mass ratio of the metal compound to TfpBpy-COF, affecting the amount of hydrogen peroxide produced. A lower mass ratio results in too little metal loading, resulting in a less pronounced effect. A higher mass ratio, on the other hand, may not be enough to improve the effect. Furthermore, excessive metal loading may form clusters within the framework, inhibiting the catalytic effect.

[0026] Preferably, the molar mass ratio of 5,5'-diamino-2,2'-bipyridine to 2,4,6-triformylphloroglucinol is 3:2.

[0027] In order to improve the reaction efficiency of the metal modification process, preferably, the heating reaction temperature in S2 is 50-110° C. and the reaction time is 4-8 h.

[0028] In a specific embodiment, in the preparation method of the metal-modified covalent organic framework material M-TfpBpy-COF of the present invention, different metal materials are modified, and the preferred temperature and time of the heating reaction are different, as follows:

[0029] The antimony-containing metal compound in S2 is sodium hexafluoroantimonate, the organic solvent is methanol, the heating temperature is 55-65° C., and the stirring and heating reaction time is 6-8 hours.

[0030] The molybdenum-containing metal compound in S2 is molybdenum hexacarbonyl, the organic solvent is toluene solvent, the heating temperature is 90-110° C., and the stirring and heating reaction time is 4-6 hours.

[0031] The chromium-containing metal compound in S2 is chromium hexacarbonyl, the organic solvent is chloroform, the heating temperature is 50-60° C., and the stirring and heating reaction time is 6-8 hours.

[0032] In order to further optimize the reaction effect, 0.6% ethanol is added to the organic solvent of chromium hexacarbonyl, chloroform, as a stabilizer.

[0033] The calcium-containing metal compound in S2 is calcium chloride, the organic solvent is anhydrous ethanol solvent, the heating temperature is 65-75° C., and the stirring and heating reaction time is 6-8 hours.

[0034] The magnesium-containing metal compound in S2 is magnesium acetate, the organic solvent is anhydrous ethanol solvent, the heating temperature is 65-75° C., and the stirring and heating reaction time is 6-8 hours.

[0035] The manganese-containing metal compound in S2 is manganese acetate, the organic solvent is anhydrous ethanol solvent, the heating temperature is 65-75° C., and the stirring and heating reaction time is 6-8 hours.

[0036] The barium-containing metal compound in S2 is barium chloride, the organic solvent is deionized water, the heating temperature is 80-100° C., and the stirring and heating reaction time is 4-6 hours.

[0037] Among them, in order to improve the reaction efficiency of the metal modification process, preferably, the organic solvent of sodium hexafluoroantimonate is methanol, the organic solvent of molybdenum hexacarbonyl is toluene, the organic solvent of chromium hexacarbonyl is chloroform, the organic solvent of calcium chloride, magnesium acetate, and manganese acetate is anhydrous ethanol, and the organic solvent of barium chloride is deionized water.

[0038] Among them, the washing in S2 is solvent centrifugal washing, and the solvents used include but are not limited to anhydrous ethanol, pure water and methanol. The number of centrifugal washings is 2 to 4 times, the vacuum drying temperature is 60 to 80°C, and the vacuum drying time is 12 to 24 hours. In order to make the piezoelectric catalytic effect of the metal-modified covalent organic framework material more excellent, the vacuum drying temperature is more preferably 80°C and the vacuum drying time is 12 hours.

[0039] Among them, in order to make the piezoelectric catalytic effect of the metal-modified covalent organic framework material more excellent, the metal compounds containing antimony, molybdenum, chromium, calcium, magnesium, manganese, and barium of the present invention are preferably selected from sodium hexafluoroantimonate, molybdenum hexacarbonyl, chromium hexacarbonyl, calcium chloride, magnesium acetate, manganese acetate, and barium chloride, respectively.

[0040] The concentration of TfpBpy-COF in the organic solvent in S2 is 1-2 mg / mL, and more preferably, the concentration of TfpBpy-COF in the organic solvent is 1.67 mg / mL.

[0041] The present invention also specifically protects the use of a metal-modified covalent organic framework material in the piezoelectric catalytic preparation of hydrogen peroxide.

[0042] The present invention further specifically protects a method for preparing hydrogen peroxide by piezoelectric catalysis, comprising the following steps:

[0043] The metal-modified covalent organic framework material M-TfpBpy-COF is uniformly dispersed to obtain a suspension, and ultrasonic mechanical vibration is used to catalyze the reaction to prepare hydrogen peroxide.

[0044] Preferably, the ultrasonic power is 20 to 200 W. Too low an ultrasonic power will result in fewer excited electrons, weaker performance, and lower hydrogen peroxide production. Too high an ultrasonic power will increase energy consumption and reduce cost-effectiveness.

[0045] Preferably, the ultrasonic power of the ultrasonic treatment of the metal-modified covalent organic framework material is 20-200W, and more preferably, the ultrasonic power of the ultrasonic treatment of the metal-modified covalent organic framework material is 110W.

[0046] Preferably, the concentration of the covalent organic framework material M-TfpBpy-COF in the suspension is 0.05-5 g / L.

[0047] Furthermore, the dosage of the piezoelectric metal-modified covalent organic framework material is 0.05 to 5 g / L. Preferably, the dosage of the piezoelectric metal-modified covalent organic framework material is 0.1 g / L, 0.2 g / L, 0.5 g / L or 1 g / L. More preferably, the dosage of the piezoelectric metal-modified covalent organic framework material is 0.2 g / L.

[0048] The piezoelectric metal-modified covalent organic framework material of the present invention can undergo redox reaction through piezoelectric catalysis, reducing molecular oxygen in water to generate hydrogen peroxide through two-electron one-step oxygen reduction, and simultaneously splitting water molecules to generate hydrogen peroxide through two-electron water oxidation.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] The metal-modified covalent organic framework M-TfpBpy-COF of the present invention can generate more electrons and shift after deformation when stimulated by mechanical vibration. Water oxidation and oxygen reduction reactions simultaneously occur at the active centers on the surface of the material to generate hydrogen peroxide. The adjustability and selectivity of the covalent organic framework structure provide abundant sites for metal loading, thereby preparing excellent piezoelectric catalytic active materials.

[0051] The metal-modified covalent organic framework M-TfpBpy-COF of the present invention has high thermal stability and strong chemical stability. After multiple cycles of catalysis, it can still maintain good structural integrity and high catalytic activity. The catalyst is easy to recover and separate and can be reused. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a scanning electron microscope (SEM) image of Sb-TfpBpy-COF prepared in Example 1.

[0053] Figure 2 This is a scanning electron microscope (SEM) image of Mo-TfpBpy-COF prepared in Example 4.

[0054] Figure 3 This is a scanning electron microscope (SEM) image of Cr-TfpBpy-COF prepared in Example 7.

[0055] Figure 4 This is the X-ray diffraction (XRD) pattern of Sb-TfpBpy-COF prepared in Example 2.

[0056] Figure 5This is the X-ray diffraction (XRD) pattern of Mo-TfpBpy-COF prepared in Example 5.

[0057] Figure 6 This is the X-ray diffraction (XRD) pattern of Cr-TfpBpy-COF prepared in Example 8.

[0058] Figure 7 These are Fourier transform infrared absorption spectra (FTIR) test spectra of M-TfpBpy-COF prepared in Examples 3, 6, 10, 12, and 14 and TfpBpy-COF prepared in Comparative Example 2.

[0059] Figure 8 This is the electron spin resonance (ESR) spectrum of superoxide radicals produced by the piezoelectric catalysis of Sb-TfpBpy-COF prepared in Example 1.

[0060] Figure 9 This is the singlet oxygen electron spin resonance (ESR) spectrum of the Sb-TfpBpy-COF piezoelectric catalytic production of hydrogen peroxide prepared in Example 1.

[0061] Figure 10 This is the electron spin resonance (ESR) spectrum of the hydroxyl radical produced by the piezoelectric catalysis of Sb-TfpBpy-COF prepared in Example 1 to produce hydrogen peroxide.

[0062] Figure 11 This is a performance test diagram of the degradation of micropollutant caffeine (CAF) by the M-TfpBpy-COF catalyst prepared in Example 1, Example 4, Example 7, and Example 13.

[0063] Figure 12 This is a graph showing the bactericidal performance of the M-TfpBpy-COF catalyst prepared in Examples 3, 6, and 9 and Comparative Example 10 against Escherichia coli (E. coli K12). DETAILED DESCRIPTION

[0064] The present invention will be further described below in conjunction with specific embodiments, but the examples do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the examples of the present invention are conventionally purchased raw materials and reagents.

[0065] The preparation methods of TfpBpy-COF in the examples and comparative examples of the present invention are as follows:

[0066] 63 mg of 2,4,6-triformylphloroglucinol and 83.7 mg of 5,5'-diamino-2,2'-bipyridine were weighed into a 15 mL internal threaded reaction vial. 4.5 mL of chromatographic-grade N,N-dimethylacetamide and 1.5 mL of o-dichlorobenzene were added, mixed thoroughly, and quickly added with 0.6 mL of 6 M acetic acid solution. The mixture was thoroughly mixed and then rapidly frozen with liquid nitrogen. The internal pressure was evacuated to a vacuum, and the reaction vial was sealed. After thawing, the reaction vial was frozen with liquid nitrogen, degassed, and thawed three times. The sealed reaction vial was then heated to 120°C for 72 hours. After the reaction, the reaction was cooled to room temperature and washed with analytical-grade N,N-dimethylacetamide, dichloromethane, acetone, and methanol. The washed solid was activated in a vacuum drying oven at 150°C for 12 hours. After cooling to room temperature, it was ground to obtain TfpBpy-COF.

[0067] Example 1

[0068] A metal-modified covalent organic framework material, the covalent organic framework material is synthesized from 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol as precursors, and the metal-modified covalent organic framework material Sb-TfpBpy-COF is obtained after metal post-modification.

[0069] Among them, the metal is chromium.

[0070] The specific preparation method of the metal-modified covalent organic framework material Sb-TfpBpy-COF of Example 1 is as follows:

[0071] 50 mg of TfpBpy-COF and 40 mg of sodium hexafluoroantimonate (NaSbF6) were added to a 150 mL round-bottom flask, and then 30 mL of methanol solution was added to the round-bottom flask. After adding a polytetrafluoroethylene stirring bar, a serpentine condenser was connected to the round-bottom flask, placed in an oil bath and stirred at 65 ° C for 6 hours, then filtered and washed with ethanol and water 4 times, and vacuum dried at 80 ° C for 12 hours to obtain the metal antimony modified covalent organic framework piezoelectric catalyst Sb-TfpBpy-COF.

[0072] The Sb-TfpBpy-COF prepared above (0.2 g / L) was uniformly dispersed in an aqueous solution and then used for piezoelectric catalysis to produce hydrogen peroxide under 110 W ultrasonic power. (For specific steps, see Application Example (5) Hydrogen Peroxide Production Performance Determination).

[0073] The Sb-TfpBpy-COF (1 g / L) prepared above was evenly dispersed in an aqueous solution and applied to piezoelectric catalysis to prepare hydrogen peroxide for degradation of water pollutants under an ultrasonic power of 110 W.

[0074] Example 2

[0075] A metal-modified covalent organic framework material, the covalent organic framework material is synthesized from 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol as precursors, and the metal-modified covalent organic framework material Sb-TfpBpy-COF is obtained after metal post-modification.

[0076] Among them, the metal is chromium.

[0077] The specific preparation method of the metal-modified covalent organic framework material Sb-TfpBpy-COF of Example 2 is as follows:

[0078] 50 mg of TfpBpy-COF and 20 mg of sodium hexafluoroantimonate (NaSbF6) were added to a 150 ml round-bottom flask, and then 30 mL of methanol solution was added to the round-bottom flask. After adding a polytetrafluoroethylene stirring bar, a serpentine condenser was connected to the round-bottom flask, and the mixture was placed in an oil bath and stirred at 65 ° C for 6 h. Then, the mixture was filtered and washed with ethanol and water 4 times, and vacuum dried at 80 ° C for 12 h to obtain the metal antimony modified covalent organic framework piezoelectric catalyst Sb-TfpBpy-COF.

[0079] The Sb-TfpBpy-COF (0.2 g / L) prepared above was placed in an aqueous solution and uniformly dispersed, and then used for piezoelectric catalysis to prepare hydrogen peroxide under an ultrasonic power of 110 W.

[0080] Example 3

[0081] A metal-modified covalent organic framework material, the covalent organic framework material is synthesized from 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol as precursors, and the metal-modified covalent organic framework material Sb-TfpBpy-COF is obtained after metal post-modification.

[0082] Among them, the metal is chromium.

[0083] The specific preparation method of the metal-modified covalent organic framework material Sb-TfpBpy-COF of Example 3 is as follows:

[0084] 50 mg of TfpBpy-COF and 60 mg of sodium hexafluoroantimonate (NaSbF6) were added to a 150 mL round-bottom flask, and then 50 mL of methanol solution was added to the round-bottom flask. After adding a polytetrafluoroethylene stirring bar, a serpentine condenser was connected to the round-bottom flask, placed in an oil bath and stirred at 55 ° C for 8 hours, then filtered and washed with ethanol and water 4 times, and vacuum dried at 80 ° C for 12 hours to obtain the metal antimony modified covalent organic framework piezoelectric catalyst Sb-TfpBpy-COF.

[0085] The Sb-TfpBpy-COF (0.5 g / L) prepared above was evenly dispersed in an aqueous solution and applied to prepare hydrogen peroxide by piezoelectric catalysis under 200 W ultrasonic power.

[0086] The prepared Sb-TfpBpy-COF (0.5 g / L) was uniformly dispersed in an aqueous solution and then used for piezoelectric catalysis to prepare hydrogen peroxide under an ultrasonic power of 200 W to kill pathogenic microorganisms in water.

[0087] Example 4

[0088] A metal-modified covalent organic framework material is synthesized from 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol as precursors, and the metal-modified covalent organic framework material Mo-TfpBpy-COF is obtained after metal post-modification.

[0089] Wherein, the metal is molybdenum.

[0090] The specific preparation method of the metal-modified covalent organic framework material Mo-TfpBpy-COF of Example 4 is as follows:

[0091] 50 mg of TfpBpy-COF and 40 mg of molybdenum hexacarbonyl (Mo(CO)6) were added to a 150 mL round-bottom flask, and then 30 mL of toluene solution was added to the round-bottom flask. After adding a polytetrafluoroethylene stirring bar, a serpentine condenser was connected to the round-bottom flask, placed in an oil bath and stirred at 110 ° C for 4 hours, then filtered and washed with ethanol and water 4 times, and vacuum dried at 80 ° C for 12 hours to obtain a metal molybdenum modified covalent organic framework piezoelectric catalyst Mo-TfpBpy-COF.

[0092] The Mo-TfpBpy-COF (0.2 g / L) prepared above was evenly dispersed in an aqueous solution and applied to the piezoelectric catalytic preparation of hydrogen peroxide under 110 W ultrasonic power.

[0093] The Mo-TfpBpy-COF (1 g / L) prepared above was evenly dispersed in an aqueous solution and applied to piezoelectric catalysis to prepare hydrogen peroxide for degradation of water pollutants under an ultrasonic power of 110 W.

[0094] Example 5

[0095] A metal-modified covalent organic framework material is synthesized from 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol as precursors, and the metal-modified covalent organic framework material Mo-TfpBpy-COF is obtained after metal post-modification.

[0096] Wherein, the metal is molybdenum.

[0097] The specific preparation method of the metal-modified covalent organic framework material Mo-TfpBpy-COF of Example 5 is as follows:

[0098] 50 mg of TfpBpy-COF and 20 mg of molybdenum hexacarbonyl (Mo(CO)6) were added to a 150 mL round-bottom flask, and then 30 mL of toluene solution was added to the round-bottom flask. After adding a polytetrafluoroethylene stirring bar, a serpentine condenser was connected to the round-bottom flask, placed in an oil bath and stirred at 110 ° C for 4 hours, then filtered and washed with ethanol and water 4 times, and vacuum dried at 80 ° C for 12 hours to obtain a metal molybdenum modified covalent organic framework piezoelectric catalyst Mo-TfpBpy-COF.

[0099] The Mo-TfpBpy-COF (0.2 g / L) prepared above was evenly dispersed in an aqueous solution and applied to the piezoelectric catalytic preparation of hydrogen peroxide under 110 W ultrasonic power.

[0100] Example 6

[0101] A metal-modified covalent organic framework material is synthesized from 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol as precursors, and the metal-modified covalent organic framework material Mo-TfpBpy-COF is obtained after metal post-modification.

[0102] Wherein, the metal is molybdenum.

[0103] The specific preparation method of the metal-modified covalent organic framework material Mo-TfpBpy-COF of Example 6 is as follows:

[0104] 50 mg of TfpBpy-COF and 60 mg of molybdenum hexacarbonyl (Mo(CO)6) were added to a 150 mL round-bottom flask, and then 50 mL of toluene solution was added to the round-bottom flask. After adding a polytetrafluoroethylene stirring bar, the serpentine condenser was connected to the round-bottom flask, placed in an oil bath and stirred at 90 ° C for 6 hours, then filtered and washed with ethanol and water 4 times, and vacuum dried at 80 ° C for 12 hours to obtain the metal molybdenum modified covalent organic framework piezoelectric catalyst Mo-TfpBpy-COF.

[0105] The Mo-TfpBpy-COF prepared above (0.5 g / L) was uniformly dispersed in an aqueous solution and then used for piezoelectric catalysis to produce hydrogen peroxide under 200 W ultrasonic power. (For specific steps, see Application Example (5) Hydrogen Peroxide Production Performance Determination).

[0106] The Mo-TfpBpy-COF (0.5 g / L) prepared above was placed in an aqueous solution and evenly dispersed. The solution was then used for piezoelectric catalysis to prepare hydrogen peroxide under an ultrasonic power of 200 W to kill pathogenic microorganisms in water.

[0107] Example 7

[0108] A metal-modified covalent organic framework material is synthesized from 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol as precursors, and the metal-modified covalent organic framework material Cr-TfpBpy-COF is obtained after metal post-modification.

[0109] Among them, the metal is chromium.

[0110] The specific preparation method of the metal-modified covalent organic framework material Cr-TfpBpy-COF of Example 7 is as follows:

[0111] 50 mg of TfpBpy-COF and 50 mg of hexacarbonyl chromium (Cr(CO)6) were added to a 150 mL round-bottom flask, and then 30 mL of chloroform solution and 0.2 mL of ethanol were added to the round-bottom flask. After adding a polytetrafluoroethylene stirring bar, a serpentine condenser was connected to the round-bottom flask, placed in an oil bath at 60 ° C and stirred for 6 h, then filtered and washed with ethanol and water 4 times, and vacuum dried at 80 ° C for 12 h to obtain the metal chromium modified covalent organic framework piezoelectric catalyst Cr-TfpBpy-COF.

[0112] The Cr-TfpBpy-COF (0.2 g / L) prepared above was evenly dispersed in an aqueous solution and applied to prepare hydrogen peroxide by piezoelectric catalysis under 110 W ultrasonic power.

[0113] The Cr-TfpBpy-COF (1 g / L) prepared above was evenly dispersed in an aqueous solution and applied to piezoelectric catalysis to prepare hydrogen peroxide for degradation of water pollutants under an ultrasonic power of 110 W.

[0114] Example 8

[0115] A metal-modified covalent organic framework material is synthesized from 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol as precursors, and the metal-modified covalent organic framework material Cr-TfpBpy-COF is obtained after metal post-modification.

[0116] Among them, the metal is chromium.

[0117] The specific preparation method of the metal-modified covalent organic framework material Cr-TfpBpy-COF of Example 8 is as follows:

[0118] 50 mg of TfpBpy-COF and 25 mg of hexacarbonyl chromium (Cr(CO)6) were added to a 150 mL round-bottom flask, and then 30 mL of chloroform solution and 0.2 ml of ethanol were added to the round-bottom flask. After adding a polytetrafluoroethylene stirring bar, a serpentine condenser was connected to the round-bottom flask, placed in an oil bath at 60 ° C and stirred for 6 hours, then filtered and washed with ethanol and water 4 times, and vacuum dried at 80 ° C for 12 hours to obtain the metal chromium modified covalent organic framework piezoelectric catalyst Cr-TfpBpy-COF.

[0119] The Cr-TfpBpy-COF (0.2 g / L) prepared above was evenly dispersed in an aqueous solution and applied to prepare hydrogen peroxide by piezoelectric catalysis under 110 W ultrasonic power.

[0120] Example 9

[0121] A metal-modified covalent organic framework material is synthesized from 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol as precursors, and the metal-modified covalent organic framework material Cr-TfpBpy-COF is obtained after metal post-modification.

[0122] Among them, the metal is chromium.

[0123] The specific preparation method of the metal-modified covalent organic framework material Cr-TfpBpy-COF of Example 9 is as follows:

[0124] 50 mg of TfpBpy-COF and 75 mg of hexacarbonyl chromium (Cr(CO)6) were added to a 150 mL round-bottom flask, and then 50 mL of chloroform solution and 0.3 mL of ethanol were added to the round-bottom flask. After adding a polytetrafluoroethylene stirring bar, a serpentine condenser was connected to the round-bottom flask, placed in an oil bath and stirred at 55 ° C for 8 h, then filtered and washed with ethanol and water 4 times, and vacuum dried at 80 ° C for 12 h to obtain the metal chromium modified covalent organic framework piezoelectric catalyst Cr-TfpBpy-COF.

[0125] The Cr-TfpBpy-COF (0.5 g / L) prepared above was evenly dispersed in an aqueous solution and applied to prepare hydrogen peroxide by piezoelectric catalysis under 200 W ultrasonic power.

[0126] The Cr-TfpBpy-COF (0.5 g / L) prepared above was placed in an aqueous solution and evenly dispersed. The solution was then used for piezoelectric catalysis to prepare hydrogen peroxide under an ultrasonic power of 200 W to kill pathogenic microorganisms in water.

[0127] Example 10

[0128] A metal-modified covalent organic framework material is synthesized from 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol as precursors, and the metal-modified covalent organic framework material Ca-TfpBpy-COF is obtained after metal post-modification.

[0129] Among them, the metal is calcium.

[0130] The specific preparation method of the metal-modified covalent organic framework material Ca-TfpBpy-COF of Example 10 is as follows:

[0131] 50 mg of TfpBpy-COF and 25 mg of calcium chloride (CaCl2) were added to a 150 mL round-bottom flask, and then 30 mL of anhydrous ethanol solution was added to the round-bottom flask. After adding a polytetrafluoroethylene stirring bar, a serpentine condenser was connected to the round-bottom flask, and the mixture was placed in an oil bath and stirred at 75 ° C for 8 h. Then, the mixture was filtered and washed with methanol and water 4 times, and vacuum dried at 80 ° C for 12 h to obtain a metal calcium-modified covalent organic framework piezoelectric catalyst Ca-TfpBpy-COF.

[0132] The Ca-TfpBpy-COF (0.2 g / L) prepared above was evenly dispersed in an aqueous solution and applied to prepare hydrogen peroxide by piezoelectric catalysis under 110 W ultrasonic power.

[0133] Example 11

[0134] A metal-modified covalent organic framework material is synthesized from 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol as precursors, and the metal-modified covalent organic framework material Ca-TfpBpy-COF is obtained after metal post-modification.

[0135] Among them, the metal is calcium.

[0136] The specific preparation method of the metal-modified covalent organic framework material Ca-TfpBpy-COF of Example 11 is as follows:

[0137] 50 mg of TfpBpy-COF and 35 mg of calcium chloride (CaCl2) were added to a 150 mL round-bottom flask, and then 30 mL of anhydrous ethanol solution was added to the round-bottom flask. After adding a polytetrafluoroethylene stirring bar, a serpentine condenser was connected to the round-bottom flask, and the mixture was placed in an oil bath and stirred at 75 ° C for 8 h. Then, the mixture was filtered and washed with methanol and water 4 times, and vacuum dried at 80 ° C for 12 h to obtain a metal calcium-modified covalent organic framework piezoelectric catalyst Ca-TfpBpy-COF.

[0138] The Ca-TfpBpy-COF (0.2 g / L) prepared above was evenly dispersed in an aqueous solution and applied to prepare hydrogen peroxide by piezoelectric catalysis under 110 W ultrasonic power.

[0139] Example 12

[0140] A metal-modified covalent organic framework material is synthesized from 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol as precursors, and the metal-modified covalent organic framework material Mg-TfpBpy-COF is obtained after metal post-modification.

[0141] Among them, the metal is magnesium.

[0142] The specific preparation method of the metal-modified covalent organic framework material Mg-TfpBpy-COF of Example 12 is as follows:

[0143] 50 mg of TfpBpy-COF and 35 mg of magnesium acetate (Mg(CH3COO)2) were added to a 150 mL round-bottom flask, and then 30 mL of anhydrous ethanol solution was added to the above round-bottom flask. After adding a polytetrafluoroethylene stirring bar, the serpentine condenser was connected to the round-bottom flask, placed in an oil bath and stirred at 75 ° C for 8 hours, then filtered and washed with methanol and water 4 times, and vacuum dried at 80 ° C for 12 hours to obtain the magnesium-modified covalent organic framework piezoelectric catalyst Mg-TfpBpy-COF.

[0144] The Mg-TfpBpy-COF (0.2 g / L) prepared above was evenly dispersed in an aqueous solution and applied to prepare hydrogen peroxide by piezoelectric catalysis under 110 W ultrasonic power.

[0145] Example 13

[0146] A metal-modified covalent organic framework material is synthesized from 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol as precursors, and the metal-modified covalent organic framework material Mg-TfpBpy-COF is obtained after metal post-modification.

[0147] Among them, the metal is magnesium.

[0148] The specific preparation method of the metal-modified covalent organic framework material Mg-TfpBpy-COF of Example 13 is as follows:

[0149] 50 mg of TfpBpy-COF and 50 mg of magnesium acetate (Mg(CH3COO)2) were added to a 150 mL round-bottom flask, and then 30 mL of anhydrous ethanol solution was added to the round-bottom flask. After adding a polytetrafluoroethylene stirring bar, the serpentine condenser was connected to the round-bottom flask, placed in an oil bath and stirred at 75 ° C for 8 h, then filtered and washed with methanol and water 4 times, and vacuum dried at 80 ° C for 12 h to obtain the magnesium-modified covalent organic framework piezoelectric catalyst Mg-TfpBpy-COF.

[0150] The Mg-TfpBpy-COF (0.2 g / L) prepared above was evenly dispersed in an aqueous solution and applied to prepare hydrogen peroxide by piezoelectric catalysis under 110 W ultrasonic power.

[0151] The Mg-TfpBpy-COF (1 g / L) prepared above was evenly dispersed in an aqueous solution and applied to piezoelectric catalysis to prepare hydrogen peroxide for degradation of water pollutants under an ultrasonic power of 110 W.

[0152] Example 14

[0153] A metal-modified covalent organic framework material, the covalent organic framework material is synthesized from 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol as precursors, and the metal-modified covalent organic framework material Mn-TfpBpy-COF is obtained after metal post-modification.

[0154] Among them, the metal is manganese.

[0155] The specific preparation method of the metal-modified covalent organic framework material Mn-TfpBpy-COF of Example 14 is as follows:

[0156] 50 mg of TfpBpy-COF and 40 mg of manganese acetate (Mn(CH3COO)2) were added to a 150 mL round-bottom flask, and then 30 mL of anhydrous ethanol solution was added to the round-bottom flask. After adding a polytetrafluoroethylene stirring bar, the serpentine condenser was connected to the round-bottom flask, placed in an oil bath and stirred at 75 ° C for 8 hours, then filtered and washed with methanol and water 4 times, and vacuum dried at 80 ° C for 12 hours to obtain the manganese modified covalent organic framework piezoelectric catalyst Mn-TfpBpy-COF.

[0157] The Mn-TfpBpy-COF (0.2 g / L) prepared above was evenly dispersed in an aqueous solution and applied to prepare hydrogen peroxide by piezoelectric catalysis under 110 W ultrasonic power.

[0158] Example 15

[0159] A metal-modified covalent organic framework material, the covalent organic framework material is synthesized from 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol as precursors, and the metal-modified covalent organic framework material Mn-TfpBpy-COF is obtained after metal post-modification.

[0160] Among them, the metal is manganese.

[0161] The specific preparation method of the metal-modified covalent organic framework material Mn-TfpBpy-COF of Example 15 is as follows:

[0162] 50 mg of TfpBpy-COF and 60 mg of manganese acetate (Mn(CH3COO)2) were added to a 150 mL round-bottom flask, and then 30 mL of anhydrous ethanol solution was added to the above round-bottom flask. After adding a polytetrafluoroethylene stirring bar, the serpentine condenser was connected to the round-bottom flask, placed in an oil bath and stirred at 75°C for 8 hours, then filtered and washed with methanol and water 4 times, and vacuum dried at 80°C for 12 hours to obtain the manganese metal modified covalent organic framework piezoelectric catalyst Mn-TfpBpy-COF.

[0163] The Mn-TfpBpy-COF (0.2 g / L) prepared above was evenly dispersed in an aqueous solution and applied to prepare hydrogen peroxide by piezoelectric catalysis under 110 W ultrasonic power.

[0164] Example 16

[0165] A metal-modified covalent organic framework material, the covalent organic framework material is synthesized from 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol as precursors, and the metal-modified covalent organic framework material Ba-TfpBpy-COF is obtained after metal post-modification.

[0166] Among them, the metal is barium.

[0167] The specific preparation method of the metal-modified covalent organic framework material Ba-TfpBpy-COF of Example 16 is as follows:

[0168] 50 mg of TfpBpy-COF and 45 mg of barium chloride (BaCl2) were added to a 150 mL round-bottom flask, and then 30 mL of deionized water was added to the round-bottom flask. After adding a polytetrafluoroethylene stirring bar, a serpentine condenser was connected to the round-bottom flask, and the mixture was placed in an oil bath and stirred at 95 ° C for 6 h. Then, the mixture was filtered and washed with ethanol and water 4 times, and vacuum dried at 80 ° C for 12 h to obtain the metal barium-modified covalent organic framework piezoelectric catalyst Ba-TfpBpy-COF.

[0169] The Ba-TfpBpy-COF (0.2 g / L) prepared above was evenly dispersed in an aqueous solution and applied to prepare hydrogen peroxide by piezoelectric catalysis under 110 W ultrasonic power.

[0170] Example 17

[0171] A metal-modified covalent organic framework material, the covalent organic framework material is synthesized from 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol as precursors, and the metal-modified covalent organic framework material Ba-TfpBpy-COF is obtained after metal post-modification.

[0172] Among them, the metal is barium.

[0173] The specific preparation method of the metal-modified covalent organic framework material Ba-TfpBpy-COF of Example 17 is as follows:

[0174] 50 mg of TfpBpy-COF and 70 mg of barium chloride (BaCl2) were added to a 150 mL round-bottom flask, and then 30 mL of deionized water was added to the round-bottom flask. After adding a polytetrafluoroethylene stirring bar, a serpentine condenser was connected to the round-bottom flask, and the mixture was placed in an oil bath and stirred at 95 ° C for 6 h. Then, the mixture was filtered and washed with ethanol and water 4 times, and vacuum dried at 80 ° C for 12 h to obtain the metal barium-modified covalent organic framework piezoelectric catalyst Ba-TfpBpy-COF.

[0175] The Ba-TfpBpy-COF (0.2 g / L) prepared above was evenly dispersed in an aqueous solution and applied to prepare hydrogen peroxide by piezoelectric catalysis under 110 W ultrasonic power.

[0176] Comparative Example 1

[0177] The ultrasonic reactor without catalyst was placed under the same conditions as in Example 1 and ultrasonicated for 1 hour. The hydrogen peroxide content was detected by DPD-POD hydrogen peroxide colorimetric spectrophotometry.

[0178] Comparative Example 2

[0179] The TfpBpy-COF prepared above (0.2 g / L) was evenly dispersed in an aqueous solution, ultrasonicated at 110 W ultrasonic power for 1 h, and the hydrogen peroxide content was detected by DPD-POD hydrogen peroxide colorimetric spectrophotometry.

[0180] Comparative Example 3

[0181] Take 25mL of E. coli with a concentration of 7log 10cfu / mL of aqueous solution in a 50mL beaker, place the beaker in an ultrasonic machine at room temperature for ultrasonic reaction, take 50μL samples at 5min, 10min, 20min, and 30min of reaction, evenly spread them on LB-agar medium, and culture in a constant temperature incubator at 37℃ for 12h. After that, record the number of colonies on the culture medium and calculate the concentration of viable E. coli remaining in the samples.

[0182] Test results

[0183] Catalyst performance testing

[0184] (1) Scanning electron microscope (SEM) detection

[0185] The Sb-TfpBpy-COF prepared in Example 1, the Mo-TfpBpy-COF prepared in Example 4, and the Cr-TfpBpy-COF prepared in Example 7 were subjected to scanning electron microscopy (SEM) detection. The detection results are as follows: Figures 1 to 3 shown.

[0186] The results show that the metal-loaded covalent organic framework materials prepared in Example 1, Example 4 and Example 7 have an interlaced linear structure and tend to aggregate into spherical shapes.

[0187] (2) X-ray diffraction (XRD) test

[0188] The Sb-TfpBpy-COF prepared in Example 2, the Mo-TfpBpy-COF prepared in Example 5, and the Cr-TfpBpy-COF prepared in Example 8 were subjected to X-ray diffraction analysis. The obtained XRD patterns are shown in FIG. Figures 4-6 As shown in the figure, the XRD spectra of the metal-modified covalent organic framework are basically consistent. 2θ = 3.68° corresponds to the (100) crystal plane, proving that the metal-modified covalent organic framework has good crystallinity. The broad peak at 2θ = 26° comes from the π-π stacking at the (002) crystal plane. All of the above prove that the metal-modified covalent organic framework has a good structure.

[0189] (3) Fourier transform infrared absorption spectroscopy (FTIR) test

[0190] The Sb-TfpBpy-COF prepared in Example 3, the Mo-TfpBpy-COF prepared in Example 6, the Ca-TfpBpy-COF prepared in Example 10, the Mg-TfpBpy-COF prepared in Example 12, the Mn-TfpBpy-COF prepared in Example 14 and the TfpBpy-COF in Comparative Example 2 were subjected to Fourier transform infrared absorption spectroscopy test, and the obtained FTIR spectrum was as shown in FIG. Figure 7 As shown, 1579cm -1 and 1608cm-1 The peak at 1265 cm indicates that the C=C functional group and the C=O functional group still exist after metal modification, proving that the structure of the covalent organic framework is intact. The peak position of C=N changes from 1265 cm -1 Move to 1270cm -1 , indicating that metal modification at the bipyridine site of the covalent organic framework stretches the C=N bond, leading to a red shift.

[0191] (4) Electron spin resonance (ESR) test

[0192] In order to fully demonstrate the piezoelectric catalysis of metal-modified covalent organic frameworks, DMPO was used as a capture reagent to detect ·OH and ·O2 in different systems. - , using TEMP as a capture reagent to detect singlet oxygen in different systems ( 1 O2). The Sb-TfpBpy-COF prepared in Example 1 was subjected to ESR detection, and the results were as follows. Figures 8-10 As shown in the figure, TEMP- 1 O2 and DMPO-·O2 - The signal proves that free radicals are generated during the piezoelectric catalysis process. Free radicals can be used for disinfection and are also intermediates in the generation of hydrogen peroxide, proving the piezoelectric effect under ultrasound drive.

[0193] (5) Determination of hydrogen peroxide production performance

[0194] 25 mL of pure water was added to a 200 mL beaker, and the M-TfpBpy-COF prepared in Examples 1 to 16 was added to uniformly disperse the catalyst in the aqueous solution. The beaker was placed in an ultrasonic machine at room temperature for ultrasonic reaction. After the reaction for 1 h, 1.5 mL of the reaction solution was aspirated, the catalyst was filtered, and 1 mL of the filtrate was added to a 10 mL colorimetric tube. Subsequently, 3 mL of pH = 6 phosphate buffer, 50 μL of 10 mg / L DPD solution, and 50 μL of 1 mg / L POD solution were added. Finally, deionized water was added to make the volume 10 mL. The hydrogen peroxide content of the mixed solution after the volume was determined was detected by ultraviolet spectrophotometer. The results are shown in Table 1.

[0195] Table 1

[0196] Group <![CDATA[H2O2 production (μmolg -1 h -1 )]]> Group <![CDATA[H2O2 production (μmolg -1 h -1 )]]> Example 1 1241.912 Example 11 832.918 Example 2 1069.434 Example 12 721.299 Example 3 1500.577 Example 13 807.616 Example 4 1203.326 Example 14 980.087 Example 5 966.216 Example 15 990.127 Example 6 1451.732 Example 16 1003.112 Example 7 984.229 Example 17 1144.499 Example 8 778.902 Comparative Example 1 0 Example 9 1161.726 Comparative Example 2 159.838 Example 10 767.411

[0197] As shown in Table 1, Examples 1-17 were used to investigate the performance of hydrogen peroxide production by changing the synthesis conditions of the metal-modified covalent organic framework and the ultrasonic power of the ultrasonic machine. The results showed that a reasonable increase in the dosage of sodium hexafluoroantimonate, molybdenum hexacarbonyl, chromium hexacarbonyl, calcium chloride, magnesium acetate, manganese acetate, and barium chloride, a proper increase in the water bath temperature during the synthesis process, and an increase in the ultrasonic power were all beneficial to increasing the yield of hydrogen peroxide. However, excessive amounts of sodium hexafluoroantimonate, molybdenum hexacarbonyl, chromium hexacarbonyl, calcium chloride, magnesium acetate, and manganese acetate were not beneficial to increasing the yield of hydrogen peroxide. , barium chloride and excessively powerful ultrasound have limited improvements in hydrogen peroxide production performance. Considering hydrogen peroxide production performance, economy and ease of operation, the dosage of sodium hexafluoroantimonate and molybdenum hexacarbonyl in the synthesis process of this system is 50 mg, the dosage of chromium hexacarbonyl and manganese acetate is 40 mg, the dosage of calcium chloride is 25 mg, the dosage of magnesium acetate is 35 mg, the dosage of barium chloride is 45 mg, the amount of organic solvent added is 30 mL, and the ultrasonic density of the ultrasonic machine is set to 110W.

[0198] As shown in Table 1, the piezoelectrically catalyzed hydrogen peroxide yields of Example 1 and Comparative Examples 1, 2, and 3 demonstrate that the piezoelectrically catalyzed hydrogen peroxide production performance of a simple covalent organic framework is very limited. However, the results of Example 1 and Comparative Example 3 indicate that the mechanical stress generated by ultrasound is the driving force for hydrogen peroxide production in the metal antimony-modified covalent organic framework. This is because the metal-modified covalent organic framework changes the internal symmetry of the framework, generating a piezoelectric effect under ultrasound drive, and the separated positive and negative charges undergo oxygen reduction and water oxidation reactions. The hydrogen peroxide yield of Example 1 under piezoelectric catalysis reached 1241.9 μmol g. -1 h -1 , very efficient.

[0199] As shown in Table 1, the piezoelectrically catalyzed hydrogen peroxide yields of Example 4 and Comparative Examples 1 and 2 show that the performance of a simple covalent organic framework in producing hydrogen peroxide under piezoelectric catalysis is very limited. However, the hydrogen peroxide yield of Example 4 under piezoelectric catalysis reached 1203.3 μmol g -1 h -1 .

[0200] In summary, the metal-modified covalent organic frameworks described in the present invention can all produce hydrogen peroxide under the mechanical stress generated by piezoelectricity, and the hydrogen peroxide yield is relatively considerable. After 1 hour of catalysis, the material was recovered and the experiment was conducted again. It was found that the catalytic effect of the material remained basically unchanged, and the hydrogen peroxide yield was comparable, showing a good cyclic catalytic effect.

[0201] (6) Pollutant degradation performance test

[0202] Take 50mL of caffeine (CAF) pollutant with a concentration of 10mg / L in a 100mL beaker, add 40μM ferrous sulfate (FeSO4), add the M-TfpBpy-COF catalyst prepared in Example 1, Example 4, Example 7, and Example 13, and evenly disperse the catalyst in the pollutant solution. Place the beaker in an ultrasonic machine at room temperature for ultrasonic reaction, take 1.5mL of the reaction solution at 0min, 2min, 5min, 10min, 15min, 30min, and 45min, filter the catalyst, absorb 1mL of the filtrate, add 0.5mL of methanol solution, mix well, and measure the remaining pollutant concentration using high performance liquid chromatography to obtain the pollutant degradation performance curve. The results are as follows Figure 11 shown.

[0203] Depend on Figure 11 The metal-modified covalent organic framework (COF) is highly effective in degrading pollutants during piezoelectric catalysis. Hydrogen peroxide reacts with ferrous ions to produce free radicals, which degrade pollutants such as caffeine. Within 45 minutes, the pollutants are almost completely degraded. These results demonstrate that COF-modified COF piezoelectric catalysis is well-suited for the degradation of water pollutants.

[0204] (7) Determination of bactericidal performance of Escherichia coli (E.coli K12)

[0205] Take 25mL of E. coli with a concentration of 7log 10 cfu / mL aqueous solution in a 50mL beaker, add the M-TfpBpy-COF catalyst prepared in Example 3, Example 6, and Example 9 to uniformly disperse the catalyst in the pollutant solution, place the beaker in an ultrasonic machine at room temperature for ultrasonic reaction, take a 50μL sample after 30 minutes of reaction, evenly spread it on LB-agar medium, and place it in a constant temperature incubator at 37℃ for 12 hours. After that, record the number of colonies on the culture medium and calculate the concentration of viable E. coli remaining in the sample. The results are as follows Figure 12 shown.

[0206] Depend on Figure 12It can be seen that Example 3, Example 6, and Example 9 are studies on the bactericidal properties of three different metal-modified covalent organic frameworks. The results show that the metal-modified covalent organic framework has obvious bactericidal properties. Comparing the bactericidal properties of Example 3, Example 6, and Example 9 with those of Comparative Example 3, it can be seen that ultrasound alone has only a very slight killing effect on water pathogenic microorganisms, mainly due to the physical damage of ultrasound to bacteria. The hydrogen peroxide and various free radicals generated by the metal-modified covalent organic framework during the piezoelectric catalysis process can significantly kill Escherichia coli. And the bactericidal rates of Example 3, Example 6, and Example 9 can all reach more than 99.99%. In summary, it can be seen that the metal-modified covalent organic framework has good application value in piezoelectric catalysis to kill water pathogenic microorganisms.

[0207] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. Application of a metal-modified covalent organic framework material in the piezoelectric catalytic preparation of hydrogen peroxide, characterized in that: The preparation method of the metal-modified covalent organic framework material comprises the following steps: S1. 5,5'-diamino-2,2'-bipyridine and 2,4,6-triformylphloroglucinol were used to synthesize bipyridine-containing TfpBpy-COF via an acetic acid-catalyzed solvothermal method. S2. The TfpBpy-COF prepared in S1 and metal compounds containing antimony, molybdenum, chromium, calcium, magnesium, manganese, and barium were added to an organic solution, heated for reaction, washed, and vacuum dried to obtain a metal-modified covalent organic framework M-TfpBpy-COF; The metal compounds containing antimony, molybdenum, chromium, calcium, magnesium, manganese and barium are respectively selected from sodium hexafluoroantimonate, molybdenum hexacarbonyl, chromium hexacarbonyl, calcium chloride, magnesium acetate, manganese acetate and barium chloride; The mass ratio of the metal compound to TfpBpy-COF is 1:0.8~2.

5.

2. The use according to claim 1, characterized in that The mass ratio of the metal compound to TfpBpy-COF is 1:1~2.

3. The use according to claim 1, wherein The molar ratio of 5,5'-diamino-2,2'-bipyridine to 2,4,6-triformylphloroglucinol is 3:

2.

4. The use according to claim 1, characterized in that The heating reaction temperature in S2 is 50-110° C., and the reaction time is 4-8 h.

5. A method for preparing hydrogen peroxide by piezoelectric catalysis, characterized in that: The steps include: The metal-modified covalent organic framework material M-TfpBpy-COF according to claim 1 is uniformly dispersed to obtain a suspension, and ultrasonic mechanical vibration is used to perform a catalytic reaction to prepare hydrogen peroxide.

6. The method for preparing hydrogen peroxide by piezoelectric catalysis according to claim 5, wherein: The ultrasonic power is 20-200 W.

7. The method for preparing hydrogen peroxide by piezoelectric catalysis according to claim 5, wherein: The concentration of the covalent organic framework material M-TfpBpy-COF in the suspension is 0.05-5 g / L.

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