Preparation and photocatalytic application of an ionic liquid-modified tetraaldehyde COF composite material

Abstract

This invention relates to the preparation and photocatalytic application of a tetraaldehyde COF composite material modified with an ionic liquid. It involves the formation of a covalent organic framework from a tetraaldehyde monomer under organic solvent reaction conditions, followed by the composite formation of an ionic liquid. The aim is to improve the efficiency of the covalent organic framework material in the photocatalytic synthesis of hydrogen peroxide. Method 1: Preparation of TfbdBpy-COF material. Method 2: Composite formation of TfbdBpy-ILs-COF material. The preparation process of this invention is simple and effective, with low reagent consumption and high yield. Furthermore, this invention can effectively improve the efficiency of photocatalytic hydrogen peroxide synthesis. This invention is applied to the field of photocatalytic hydrogen peroxide synthesis. Experimental data shows that the addition of an ionic liquid significantly improves the performance of photocatalytic hydrogen peroxide synthesis. Under visible light (420 nm) irradiation, the photocatalytic hydrogen peroxide yield of the ionic liquid-COF composite material reaches 1.4 mmol / g. ‑1 .h ‑1 It is 4 times the performance of COF alone.

Description

Technical fields:

[0001] This invention relates to the preparation of an ionic liquid-modified tetraaldehyde COF composite material and the photocatalytic synthesis of hydrogen peroxide from water and oxygen. Background Technology

[0002] Hydrogen peroxide (H2O2) is an important industrial product widely used in pharmaceuticals, chemical synthesis, fuels, and other fields. It can also be used as a green fuel in zero-carbon fuel cell power generation, producing oxygen and water as byproducts that are pollution-free. The demand for H2O2 is constantly growing, and it is estimated that global demand will reach 5.7 million tons by 2027. Currently, over 95% of H2O2 is produced through traditional methods, particularly the anthraquinone (AQ) process, which involves multiple steps including anthraquinone hydrogenation, H2O2 solution extraction, purification, and concentration. This method is extremely energy-intensive and produces many toxic byproducts. Therefore, using atmospheric oxygen and sunlight as raw materials and energy to produce H2O2 is a green and sustainable approach.

[0003] Covalent organic frameworks (COFs), as emerging organic semiconductor materials, are crystalline porous materials with high crystallinity and porosity. Their structure is mainly composed of light elements such as C, N, O, and B connected by reversible covalent bonds in a periodic arrangement. COFs exhibit outstanding advantages in terms of high stability under water, organic solvents, and acidic / alkaline conditions. Therefore, by adjusting the topological structure of 2D covalent organic frameworks (COFs) to enhance their H2O2 photosynthetic activity, and by introducing ionic liquids, the high conductivity, hydrophilicity, hydrophobicity, chemical durability, thermodynamic stability, and structural tunability of ionic liquids can effectively adsorb oxygen, further improving the performance of H2O2 photosynthesis. Summary of the Invention

[0004] The purpose of this invention is to solve the problem of low efficiency in the photocatalytic synthesis of hydrogen peroxide using existing materials, and to provide a method for preparing ionic liquid-modified tetraaldehyde COF composite materials and for the photocatalytic synthesis of hydrogen peroxide from water and oxygen.

[0005] The method for preparing materials by controlling the topology of COF and composite ionic liquids according to the present invention is carried out according to the following steps:

[0006] I. Preparation of TfbdBpy-COF materials:

[0007] 3,3',5,5'-Tetraformyl-4,4'-dihydroxybiphenyl (Tfbd) and [2,2'-bipyridine]-5,5'-diamine (Bpy) were added to a heat-resistant glass tube, followed by the addition of a mixed solution of n-butanol, o-dichlorobenzene, and acetic acid. The mixture was ultrasonically treated at a frequency of 40 kHz for 30–35 min, degassed by three freeze-thaw cycles in a liquid nitrogen bath, sealed, and heated at 80–120 °C for 72–120 h. After filtration and washing several times with tetrahydrofuran, the mixture was vacuum dried for 12 h to obtain the TfbdBpy-COF material.

[0008] II. Preparation of Ionic Liquid Composite Materials:

[0009] 3,3',5,5'-Tetracarboxylo-4,4'-dihydroxybiphenyl (Tfbd) and [2,2'-bipyridine]-5,5'-diamine (Bpy) were added to a heat-resistant glass tube, followed by the addition of a mixed solution of n-butanol, o-dichlorobenzene, and 1-vinyl-3-ethylimidazolium tetrafluoroborate. The mixture was sonicated at 40 kHz for 30–35 min, then boron trifluoride ether was added and stirred for 30–35 min. Acetic acid and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone were added and stirring continued for 10 min. The mixture was degassed by three freeze-thaw cycles in a liquid nitrogen bath, sealed, and heated at 80–120 °C for 72–120 h. After filtration and washing several times with tetrahydrofuran, the mixture was vacuum dried for 12 h to obtain TfbdBpy-ILs-COF.

[0010] In step one, the masses of 3,3',5,5'-tetracarboxylo-4,4'-dihydroxybiphenyl and [2,2'-bipyridine]-5,5'-diamine are 10–15.07 mg and 12.4–18.6 mg, respectively.

[0011] The acetic acid concentration mentioned in step one is 17.5 mol·L⁻¹. -1 .

[0012] The sealing process described in step one involves heating at 120°C for 72 hours.

[0013] The volume ratio of n-butanol to acetic acid in step one is 5:1.

[0014] The mass of 1-vinyl-3-ethylimidazolium tetrafluoroborate described in step two is 15 mg.

[0015] The volume of boron trifluoride diethyl ether in step two is 10 μL.

[0016] The mass of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone mentioned in step two is 4 mg.

[0017] The volume of acetic acid in step two is 0.2 ml.

[0018] The beneficial effects of this invention are:

[0019] This invention employs a solvothermal method, using 3,3',5,5'-tetracarboxylo-4,4'-dihydroxybiphenyl and [2,2'-bipyridine]-5,5'-diamine as raw materials, to successfully synthesize TfbdBpy-COF material. However, this material exhibits poor visible light absorption, with the amount of hydrogen peroxide synthesized being only 0.3–0.4 mmol / h. -1 .g -1 Therefore, by adding 1-vinyl-3-ethylimidazolium tetrafluoroborate to the original system, a new material was formed by linking the ionic liquid with a covalent organic framework. This material effectively improves visible light absorption, thereby enhancing performance. The photosynthesis efficiency of hydrogen peroxide using the TfbdBpy-ILs-COF material is 1.3–1.4 mmol·h⁻¹. -1 .g -1 . Attached Figure Description

[0020] Figure 1 Infrared spectra of two materials, TfbdBpy-COF and TfbdBpy-ILs-COF;

[0021] Figure 2 X-ray powder diffraction patterns of two materials, TfbdBpy-COF and TfbdBpy-ILs-COF;

[0022] Figure 3 Scanning electron microscope images of two materials, TfbdBpy-COF and TfbdBpy-ILs-COF;

[0023] Figure 4 A comparison of the hydrogen peroxide production performance of two materials, TfbdBpy-COF and TfbdBpy-ILs-COF; Detailed Implementation

[0024] The present invention will be further illustrated below with examples. These examples are only for illustrating the method of the present invention and do not limit the scope of application of the present invention in any way.

[0025] Example 1: The materials for this embodiment are prepared according to the following steps:

[0026] I. Preparation of TfbdBpy-COF: 15.07 mg of 3,3',5,5'-tetracarboxylo-4,4'-dihydroxybiphenyl and 18.6 mg of [2,2'-bipyridine]-5,5'-diamine were added to a heat-resistant glass tube, followed by the addition of 1 ml of n-butanol and 1 ml of o-dichlorobenzene. The mixture was sonicated at 40 kHz for 30–35 min, and then a 17.5 mol / L solution was added. -10.2 ml of acetic acid solution was degassed by three freeze-thaw cycles in a liquid nitrogen bath and heated at 120 °C for 72 h. After the temperature dropped to room temperature, it was washed several times with tetrahydrofuran solution and dried to obtain TfbdBpy-COF.

[0027] II. Preparation of TfbdBpy-ILs-COF: 15.07 mg of 3,3',5,5'-tetracarboxylo-4,4'-dihydroxybiphenyl and 18.6 mg of [2,2'-bipyridine]-5,5'-diamine were added to a heat-resistant glass tube, followed by the addition of 1 ml of n-butanol and 1 ml of o-dichlorobenzene solution. The mixture was sonicated at room temperature for 1 h, and then 15 mg of 1-vinyl-3-ethylimidazolium tetrafluoroborate was added. The sonication temperature should be controlled below 30 °C. Then, 4 mg of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone solution (dissolved in 0.2 ml of acetic acid) was added. The mixture was then subjected to three freeze-thaw cycles in a liquid nitrogen bath for degassing and heated at 120 °C for 72 h. After the temperature was lowered to room temperature, the sample was washed several times with tetrahydrofuran solution and dried to obtain the sample.

[0028] The following experiments were conducted to verify the beneficial effects of the present invention:

[0029] To investigate the photocatalytic synthesis of hydrogen peroxide using TTfbdBpy-COF and TfbdBpy-ILs-COF materials, their visible light photocatalytic hydrogen peroxide synthesis performance was tested using the following method. The test procedure was as follows: TfbdBpy-COF and TfbdBpy-ILs-COF (10 mg) were used as photocatalysts, and deionized water was used as the reaction solution. The mixture was sonicated for 30 min to form a homogeneous suspension. The suspension was poured into a reactor, and oxygen was introduced for 20 min to purge the air from the reactor. A xenon lamp was then used as the light source, and the mixture was irradiated for 30 min. The resulting suspension was then filtered through a 1 mL syringe with a filter tip to remove the catalyst, and the liquid was collected. 1 mL of the collected liquid was added to 1 mL of 0.4 mol / L potassium iodide solution and 0.5 mL of 0.1 mol / L hydrogen phthalate solution. The mixture was thoroughly mixed and allowed to stand for 30 min. The mixture was then analyzed using a UV-Vis spectrophotometer. Figure 4 As shown, under visible light, the photocatalytic synthesis efficiency of TfbdBpy-COF for hydrogen peroxide is low, only 0.35 mmol·h⁻¹. -1 .g -1 The TfbdBpy-ILs-COF material exhibited excellent photocatalytic performance in the synthesis of hydrogen peroxide, with a photocatalytic hydrogen peroxide production efficiency of 1.4 mmol·h⁻¹. -1 .g -1 .

Claims

1. Application of an ionic liquid modified tetrakisaldehyde COF composite material in photocatalytic synthesis of hydrogen peroxide, characterized in that, The ionic liquid modified tetracarbonyl COF composite material is prepared according to the following steps: Preparation of TfbdBpy-ILs-COF material: 3,3',5,5'-tetracarbonyl-4,4'-dihydroxydiphenyl and [2,2'-bipyridine]-5,5'-diamine are added into a heat-resistant glass tube, followed by adding n-butanol, o-dichlorobenzene and 1-ethenyl-3-ethyl imidazole tetrafluoroborate, stirring after ultrasonic, continuously stirring and then adding acetic acid solution and 2,3-(DDQ), degassing for three times of freeze-thaw cycle in liquid nitrogen bath, sealing, heating, filtering and washing several times with tetrahydrofuran, drying to obtain the material TfbdBpy-ILs-COF.

2. Use according to claim 1, characterized in that, The mass ratio of 3,3',5,5'-tetracarbonyl-4,4'-dihydroxydiphenyl and [2,2'-bipyridine]-5,5'-diamine is 1:

2.

3. Use according to claim 1, characterized in that, The heating time after sealing is 72-120h.

4. Use according to claim 1, characterized in that, The heating temperature after sealing is 120-150℃.

5. The use according to claim 1, characterized in that, The volume ratio of n-butanol and acetic acid is 5:1.

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