A cobalt-coordinated pyrene-bipyridyl d-a type covalent organic framework photocatalyst as well as a preparation method and application thereof
By preparing a cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst, the problem of severe recombination of photogenerated electron/hole pairs in photocatalysts was solved, achieving efficient CO2 reduction to syngas production with excellent catalytic performance and stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FUDAN UNIVERSITY
- Filing Date
- 2026-01-13
- Publication Date
- 2026-06-12
AI Technical Summary
Existing photocatalysts suffer from severe recombination of photogenerated electron/hole pairs, resulting in poor catalytic activity and making it difficult to efficiently photocatalyze the reduction of CO2 to syngas.
A cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst was prepared by Schiff base condensation reaction and then modified with cobalt metal to form a cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst. Combined with visible light, sacrificial reagents, and photosensitizers, efficient CO2 reduction was achieved.
Under visible light irradiation, the catalyst exhibits a high syngas generation rate of 23.3 mmol g−1.h−1, demonstrating good stability, a broad light response range, and abundant metal active sites, which significantly enhances catalytic activity.
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Figure CN122188084A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of photocatalytic carbon dioxide reduction technology, specifically relating to a cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst, its preparation method, and its application. Background Technology
[0002] The increasing consumption of traditional fossil fuels (such as oil, natural gas, and coal) leads to massive amounts of CO2 being directly emitted into the atmosphere, causing serious environmental problems (such as ocean acidification and the greenhouse effect) and an energy crisis. Therefore, people are vigorously exploring renewable and clean energy sources. Syngas (a mixture of CO and H2), as a key raw material for the Fischer-Tropsch synthesis to produce high-value-added fuels and chemicals, is widely considered an energy carrier with emission reduction potential. Using CO2 as a carbon source to produce syngas can not only effectively alleviate energy supply pressure but also play a significant role in achieving carbon neutrality. However, current industrial production of syngas mainly relies on water-gas shift reactions or coal gasification / natural gas reforming processes. These traditional methods suffer from problems such as high fossil fuel consumption and stringent reaction conditions. Photocatalytic CO2 reduction to syngas provides a promising technological path for achieving a sustainable carbon cycle. This method uses solar energy as an energy source and has advantages such as atmospheric pressure operation and simple process.
[0003] Covalent organic frameworks (COFs) are a class of porous organic polymer materials with high specific surface area and well-defined crystal structures. Two-dimensional COFs with extended π-conjugated structures typically exhibit excellent photogenerated charge separation and transport performance. Among them, DA-type COFs can effectively induce intramolecular charge transfer, thereby improving the separation and migration efficiency of photogenerated electron / hole pairs. Due to their precisely designable framework structures and flexible functionalization properties, COFs have become a hot material in photocatalytic CO2 reduction research. The open and ordered pore structure of COFs can fully expose metal active sites, significantly enhancing their catalytic activity compared to supports. Therefore, transition metal-modified photocatalysts based on COFs have been successively developed for CO2 reduction research. Summary of the Invention
[0004] To overcome the problems of severe recombination of photogenerated electron / hole pairs and poor catalytic activity in existing catalysts, the main objective of this invention is to provide a cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst that significantly improves photocatalytic activity and is a good visible light photocatalytic material.
[0005] Another objective of this invention is to provide a method for preparing the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst, which is simple in process and easy to scale up for production.
[0006] Another object of the present invention is to provide the application of the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst in the photocatalytic reduction of CO2 to prepare syngas.
[0007] To achieve the above objectives, the present invention adopts the following technical solution:
[0008] In a first aspect, the present invention provides a method for preparing a cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst, comprising the steps of:
[0009] (I) Using 1,3,6,8-tetra-(p-aminophenyl)-pyrene as an electron donor and 3,3'-bipyridine-6,6'-dicarboxaldehyde as an electron acceptor, a pyrene-bipyridine-DA type covalent organic framework (Py3Bpy) was obtained by Schiff base condensation reaction.
[0010] (II) The pyrene-bipyridyl DA-type covalent organic framework is modified with cobalt metal by cobalt chloride to obtain a cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst (Py3Bpy-Co).
[0011] Preferably, the preparation method of the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst follows the technical route as follows:
[0012]
[0013] Specifically, it includes the following steps:
[0014] (1) Preparation of pyrene-bipyridyl DA-type covalent organic framework: 1,3,6,8-tetra-(p-aminophenyl)-pyrene as electron donor and 3,3'-bipyridin-6,6'-dicarboxaldehyde as electron acceptor were placed together in a Pilex glass tube, and mesitylene and 1,4-dioxane were added. After degassing through three freeze-thaw cycles, Schiff base condensation reaction was carried out at 120 °C for 72 h. After cooling to room temperature, the precipitate was collected by filtration and washed with ethanol and tetrahydrofuran by vacuum filtration. The obtained solid was dried under vacuum at 80 °C overnight to obtain a reddish-brown solid powder, which is the pyrene-bipyridyl DA-type covalent organic framework.
[0015] (2) Preparation of cobalt-coordinated pyrene-bipyridyl DA type covalent organic framework photocatalyst: The reddish-brown solid powder and cobalt chloride described in step (1) were added to methanol, heated to reflux and stirred for 24 h; after cooling to room temperature, the precipitate was collected by filtration, washed with water and ethanol respectively, and the obtained solid was vacuum dried at 80 °C overnight to obtain a dark reddish-brown solid product, namely cobalt-coordinated pyrene-bipyridyl DA type covalent organic framework photocatalyst.
[0016] Preferably, in step (1), the molar ratio of 1,3,6,8-tetra-(p-aminophenyl)-pyrene and 3,3'-bipyridine-6,6'-dicarboxaldehyde is 1:2.
[0017] Preferably, in step (1), the volume ratio of mesitylene and 1,4-dioxane is 1:1.
[0018] Preferably, in step (2), the mass-to-volume ratio of the pyrene-bipyridyl DA-type covalent organic framework to methanol is 2.31:1 mg / mL.
[0019] Preferably, in step (2), the mass-to-volume ratio of cobalt chloride to methanol is 1.34:1 mg / mL.
[0020] Preferably, the preparation method of the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst includes:
[0021] (a) Preparation of pyrene-bipyridyl DA-type covalent organic framework: 0.05 mmol of electron donor 1,3,6,8-tetra-(p-aminophenyl)-pyrene and 0.10 mmol of electron acceptor 3,3'-bipyridine-6,6'-dicarboxaldehyde were placed in a 10 mL Pilex glass tube, 2 mL of mesitylene and 2 mL of 1,4-dioxane were added, and after degassing through three freeze-thaw cycles, Schiff base condensation reaction was carried out at 120 °C for 72 h; after cooling to room temperature, the precipitate was collected by filtration, washed three times by vacuum filtration with ethanol and tetrahydrofuran, respectively, and the obtained solid was dried under vacuum at 80 °C overnight to obtain a reddish-brown solid powder;
[0022] (b) Preparation of cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst: 23.1 mg of the reddish-brown solid powder described in step (a) and 13.4 mg of cobalt chloride were added to 10 mL of methanol, heated to reflux, and stirred for 24 h; after cooling to room temperature, the precipitate was collected by filtration, washed with water and ethanol respectively, and the obtained solid was dried under vacuum at 80 °C overnight to obtain a dark reddish-brown solid product, which is the product.
[0023] In a second aspect, the present invention provides a cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst, which is prepared by the method for preparing the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst.
[0024] A third aspect of the present invention provides the application of the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst in the photocatalytic reduction of CO2 to syngas, which can achieve high efficiency in the reduction of CO2 to syngas under visible light irradiation and in the presence of sacrificial reagents and photosensitizers.
[0025] Preferably, the sacrificial agent is 2,2'-bipyridine, and the photosensitizer is tris(2,2'-bipyridine)ruthenium dichloride.
[0026] Compared with the prior art, the present invention has the following beneficial effects:
[0027] (1) This invention prepares a pyrene-bipyridyl DA-type covalent organic framework from 1,3,6,8-tetra-(p-aminophenyl)-pyrene and 3,3'-bipyridine-6,6'-dicarboxaldehyde as raw materials, and then modifies it with cobalt metal. Under visible light irradiation and in the presence of sacrificial reagents and photosensitizers, a high syngas generation rate of 23.3 mmol g can be achieved. −1 .h −1 (The molar ratio of CO to H2 is 1:0.82). The catalyst showed no significant activity decay after 20 hours of continuous use, indicating extremely high application potential.
[0028] (2) The cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst of the present invention extends the π conjugated structure, giving it a wide range of photoresponse (band gap of 2.20 eV), making it a good visible light photocatalytic material. It also has a DA structure, which effectively promotes the separation and transfer of photogenerated carriers, and provides a large number of surface metal catalytic active sites, significantly improving photocatalytic activity.
[0029] (3) The cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst of the present invention improves the internal charge separation efficiency due to the introduction of metal sites, while exposing abundant metal active sites to promote the photocatalytic CO2 reduction reaction.
[0030] (4) The preparation method of the present invention is simple, and the prepared cobalt coordinated pyrene-bipyridyl DA type covalent organic framework photocatalyst has high photocatalytic activity and can efficiently convert greenhouse gas CO2 into high-value-added reduction products, and has broad market application prospects. Attached Figure Description
[0031] Figure 1 This is a schematic diagram of the synthesis of the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst in Example 1.
[0032] Figure 2 The infrared spectrum of the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst in Example 1 is shown.
[0033] Figure 3 Fine X-ray photoelectron spectroscopy of the N 1s orbital of the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst in Example 1.
[0034] Figure 4The image shows the UV spectrum of the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst in Example 1.
[0035] Figure 5 This is a stability test diagram of the photocatalytic CO2 reduction to syngas production using the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst in Example 1. Detailed Implementation
[0036] To more fully understand and demonstrate the technical solutions, objectives, and advantages of the present invention, the technical effects produced by the present invention will be further described in detail and completely below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. It should be noted that other embodiments obtained by those skilled in the art without departing from the concept of the present invention are all within the protection scope of the present invention.
[0037] Example 1
[0038] This embodiment proposes a method for preparing a cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst, which is prepared according to the following steps:
[0039] Step 1, as follows Figure 1 As shown, the preparation of the pyrene-bipyridyl DA-type covalent organic framework was as follows: 0.0284 g and 0.05 mmol of electron donor 1,3,6,8-tetra-(p-aminophenyl)-pyrene and 0.0212 g and 0.10 mmol of electron acceptor 3,3'-bipyridine-6,6'-dicarboxaldehyde were placed in a 10 mL Pilex glass tube, followed by the addition of 2 mL of mesitylene and 2 mL of 1,4-dioxane. After three freeze-thaw cycles for degassing, a Schiff base condensation reaction was carried out at 120 °C for 72 h. After cooling to room temperature, the precipitate was collected by filtration and washed three times with ethanol and tetrahydrofuran through vacuum filtration. The obtained solid was dried under vacuum at 80 °C overnight to obtain a reddish-brown solid powder.
[0040] Step 2, Preparation of cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework: 23.1 mg of the reddish-brown solid powder from Step 1 and 13.4 mg of cobalt chloride were added to 10 mL of methanol, heated to reflux, and stirred for 24 h; after cooling to room temperature, the precipitate was collected by filtration and washed with water and ethanol; the obtained solid was dried under vacuum at 80 °C overnight to obtain the final product, a dark reddish-brown solid product, which is the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst.
[0041] The infrared spectrum of the above cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst is as follows: Figure 2 As shown, at 3330cm −1The characteristic amino peak at 1690 cm⁻¹ and at 1690 cm⁻¹ −1 The aldehyde stretching vibration peaks at 1610 cm⁻¹ all disappeared completely, while the peaks at 1610 cm⁻¹ also disappeared. −1 Imine bond signals were detected nearby; Figure 3 In the fine X-ray photoelectron spectrum of the N 1s orbital, the binding energies of imine N and pyridine N in Py3Bpy were observed to be 399.3 eV and 400.6 eV, respectively, while the corresponding binding energies in Py3Bpy-Co shifted to 399.5 eV and 400.9 eV, respectively. Figure 4 The ultraviolet spectrum revealed that the catalyst's absorption edge was 564 nm.
[0042] Example 2
[0043] The cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst prepared in Example 1 was subjected to a photocatalytic CO2 reduction to syngas production experiment to evaluate its catalytic activity.
[0044] The experimental procedure was as follows: 2 mg of cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst powder, 10 mg of photosensitizer tris(2,2'-bipyridine) ruthenium dichloride, and 5 mg of sacrificial reagent 2,2'-bipyridine were added to the photoreactor. Then, 9 mL of acetonitrile, 1 mL of water, and 2 mL of triethanolamine were added. The resulting mixture suspension was sonicated until the catalyst was completely dispersed, then purged with CO2 for 30 minutes. The circulating water temperature was set to 25℃, and the mixture was irradiated for 5 h under a 300W xenon lamp equipped with a 420 nm cutoff filter (λ>420 nm). The components and concentrations of the reduction products were detected using a gas chromatograph (Shimadzu GC 2014-C) equipped with a thermal conductivity detector (TCD) and a flame ionization detector (FID). The results are as follows: Figure 5 As shown.
[0045] Figure 5 It can be seen that in the first 5 hours of light-induced reaction, the overall syngas production rate reached 23.3 mmol g. −1 h −1 (CO to H2 molar ratio of 1:0.82) indicates that the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst has an excellent CO2 reduction capacity, and its overall performance is superior to existing conjugated organic polymer photocatalysts. After five cycles of stability testing, the photocatalytic performance remained essentially unchanged, indicating that this photocatalyst has good photostability.
[0046] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for preparing a cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst, characterized in that, Includes the following steps: (I) Using 1,3,6,8-tetra-(p-aminophenyl)-pyrene as an electron donor and 3,3'-bipyridine-6,6'-dicarboxaldehyde as an electron acceptor, a pyrene-bipyridine-DA type covalent organic framework was obtained by Schiff base condensation reaction; (II) The pyrene-bipyridyl DA-type covalent organic framework is modified with cobalt metal by cobalt chloride to obtain a cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst.
2. The method for preparing the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst according to claim 1, characterized in that, Includes the following steps: (1) Using 1,3,6,8-tetra-(p-aminophenyl)-pyrene as an electron donor and 3,3'-bipyridine-6,6'-dicarboxaldehyde as an electron acceptor, they were placed together in a Pilex glass tube, and mesitylene and 1,4-dioxane were added. After degassing through three freeze-thaw cycles, Schiff base condensation reaction was carried out at 120 °C. After cooling to room temperature, the precipitate was collected by filtration and washed with ethanol and tetrahydrofuran under reduced pressure. The obtained solid was dried under vacuum at 80 °C overnight to obtain a reddish-brown solid powder, which is the pyrene-bipyridine DA type covalent organic framework. (2) The reddish-brown solid powder and cobalt chloride mentioned in step (1) are added to methanol, heated under reflux, stirred, cooled to room temperature, the precipitate is collected by filtration, washed with water and ethanol respectively, and the obtained solid is vacuum dried at 80°C overnight to obtain a dark reddish-brown solid product, namely cobalt coordinated pyrene-bipyridyl DA type covalent organic framework photocatalyst.
3. The method for preparing the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst according to claim 2, characterized in that, In step (1), the molar ratio of 1,3,6,8-tetra-(p-aminophenyl)-pyrene and 3,3'-bipyridine-6,6'-dicarboxaldehyde is 1:
2.
4. The method for preparing the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst according to claim 2, characterized in that, In step (1), the volume ratio of mesitylene and 1,4-dioxane is 1:
1.
5. The method for preparing the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst according to claim 2, characterized in that, In step (2), the mass-to-volume ratio of the pyrene-bipyridyl DA-type covalent organic framework to methanol is 2.31:1 mg / mL; the mass-to-volume ratio of cobalt chloride to methanol is 1.34:1 mg / mL.
6. The method for preparing the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst according to claim 1, characterized in that, Includes the following steps: (a) 0.05 mmol of 1,3,6,8-tetra-(p-aminophenyl)-pyrene and 0.10 mmol of 3,3'-bipyridine-6,6'-dicarboxaldehyde were placed in a 10 mL Pilex glass tube, and 2 mL of mesitylene and 2 mL of 1,4-dioxane were added. After degassing through three freeze-thaw cycles, the mixture was subjected to a Schiff base condensation reaction at 120 °C for 72 h. After cooling to room temperature, the precipitate was collected by filtration and washed three times with ethanol and tetrahydrofuran under reduced pressure. The resulting solid was dried under vacuum at 80 °C overnight to obtain a reddish-brown solid powder. (b) Add 23.1 mg of the reddish-brown solid powder described in step (a) and 13.4 mg of cobalt chloride to 10 mL of methanol, heat under reflux and stir for 24 h; after cooling to room temperature, filter and collect the precipitate, wash with water and ethanol respectively, and dry the obtained solid under vacuum at 80 °C overnight to obtain a dark reddish-brown solid product, which is the product.
7. A cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst, characterized in that, The photocatalyst was prepared by the method described in any one of claims 1-6 for cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst.
8. The application of the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst of claim 7 in the photocatalytic reduction of CO2 to prepare syngas.
9. The application according to claim 8, characterized in that, Under visible light irradiation and in the presence of sacrificial reagents and photosensitizers, the cobalt-coordinated pyrene-bipyridyl DA-type covalent organic framework photocatalyst can efficiently photocatalyze the reduction of CO2 to syngas.
10. The application according to claim 9, characterized in that, The sacrificial agent is 2,2'-bipyridine, and the photosensitizer is tris(2,2'-bipyridine)ruthenium dichloride.