Electron beam irradiation modified active metal supported covalent organic framework material and preparation method and application thereof

Abstract

The application discloses an electron beam irradiation modified active metal loaded covalent organic framework material and a preparation method and application thereof, and belongs to the technical field of environmental science and material science. The application first prepares a metalized COF material, namely M-COF (wherein, M=Co, Ni or Cu; COF is Btt-Bpy-COF) material through a post-modification method, and innovatively introduces an electron beam irradiation modification method on the basis, and successfully constructs a series of eM-COF materials. In the constructed eM-COF, the metal active sites are stably anchored on the COF skeleton, and meanwhile, the energy band structure and charge separation efficiency of the material are optimized, so that the material can be used as a high-efficiency photocatalyst for CO2 reduction. Compared with the M-COF material, the eM-COF material significantly improves the photocatalytic CO2 reduction efficiency, and effectively inhibits the hydrogen evolution side reaction in the aqueous system. The application effectively breaks through the technical bottleneck of the current COF-based photocatalyst in the core performance indexes such as active site regulation, electronic structure optimization and selective CO2 reduction.

Description

Technical Field

[0001] This invention belongs to the fields of environmental science and materials science and technology, specifically relating to an electron beam irradiation modified active metal covalent organic framework material, its preparation method and application. Background Technology

[0002] The excessive combustion of fossil fuels leads to excessive emissions of carbon dioxide (CO2), causing global warming and ecological degradation. Therefore, the development of efficient CO2 capture and resource conversion technologies is urgently needed. Photocatalytic CO2 reduction reactions can utilize clean and renewable solar energy to convert CO2 into high-value-added chemical fuels such as carbon monoxide, methane, and methanol, representing a green and effective way to reduce CO2 emissions and simultaneously alleviate the energy crisis. The conversion efficiency and selectivity of photocatalytic CO2 reduction are highly dependent on the structure and performance of the photocatalyst. An ideal catalyst needs to possess excellent CO2 adsorption capacity, good CO2 activation performance, and rapid charge transport capabilities. In recent years, researchers have successively developed various photocatalytic materials, including inorganic semiconductors, molecular catalysts, metal-organic frameworks (MOFs), and covalent organic frameworks (COFs). Among them, COFs, as a new type of crystalline porous organic polymer, have attracted much attention due to their high specific surface area, permanent porosity, ordered pore structure, and precisely tunable molecular design capabilities. However, pure COF materials are composed of organic building blocks and lack intrinsic catalytic active centers required for CO2 photoreduction, resulting in low photocatalytic conversion efficiency and poor product selectivity, which limits their practical applications. To overcome these problems, researchers have attempted to introduce metal active centers into the COF framework to construct composite materials. Among them, single-atom catalysts (SACs) have become an ideal choice for optimizing COF catalytic performance due to their advantages such as well-defined active sites, maximized atom utilization, and tunable structure and electronic properties. By controlling the type of metal center (such as Co, Ni, Cu, etc.) and the primary coordination environment (N, O, S, etc.), the band structure and surface reactivity of the catalyst can be effectively adjusted. However, existing metal modification strategies still face a series of challenges: the anchoring stability of single-atom metals on the COF support is insufficient, and agglomeration and deactivation are prone to occur; the electronic interaction between the active sites and the support is weak, making it difficult to achieve precise control of catalytic performance; and the adsorption kinetics and catalytic selectivity of CO2 in the COF framework still need to be improved. Therefore, it is urgent to develop a modification method that can efficiently anchor metal atom active sites and synergistically optimize the electronic structure and surface reactivity of COF. Summary of the Invention

[0003] The purpose of this invention is to provide an electron beam irradiation modified active metal covalent organic framework material, its preparation method, and its application, so as to solve the above-mentioned problems.

[0004] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of this invention is to provide a method for preparing an electron beam irradiation modified active metal-supported covalent organic framework material, comprising the following steps: COF material and active metal salt are co-dispersed in a solvent, and after reaction, active metal covalent organic framework (M-COF) material is obtained; the active metal covalent organic framework material is dispersed in a mixed solvent of 1,4-dioxane and 1,3,5-trimethylbenzene, and then subjected to electron beam irradiation in an inert atmosphere to obtain electron beam irradiation modified active metal covalent organic framework (eM-COF) material (e represents electron beam irradiation). The COF material is Btt-Bpy-COF; The active metal salts include: cobalt salts, nickel salts, or copper salts.

[0005] This invention prepares metallized M-COFs (M = Co, Ni, Cu) via a post-modification method, with the metal active sites stably anchored on the COF framework. Based on this, an innovative electron beam irradiation modification method is used to obtain eM-COF materials. Electron beam irradiation modification can introduce defect structures into M-COFs (M = Co, Ni, Cu), enhance the interaction between the metal active sites and the COF framework, regulate the electronic density of states, and optimize the band structure and photogenerated carrier separation efficiency of the catalyst. This allows it to be used as a highly efficient photocatalyst for CO2 reduction. Compared with M-COF materials, eM-COF materials significantly improve the photocatalytic CO2 reduction efficiency and effectively suppress hydrogen evolution side reactions in aqueous systems. In the electron beam irradiation modification step of this invention, the mixed solvent composed of 1,4-dioxane and 1,3,5-trimethylbenzene plays three main roles: first, it ensures uniform dispersion of COF and prevents aggregation through polarity matching and π-π interactions; second, it generates highly active species such as free radicals and solvated electrons under irradiation, thereby reducing the loaded metal ions or grafting modification to the framework; and third, the high-boiling-point 1,3,5-trimethylbenzene occupies the pores during irradiation to prevent framework collapse, leaving an open pore structure after solvent removal. This invention effectively overcomes the technical bottlenecks of current COF-based photocatalysts in core performance indicators such as active site regulation, electronic structure optimization, and selective CO2 reduction, and is expected to promote the development of CO2 resource utilization technology.

[0006] The theoretical basis of this invention is as follows: COF, due to its high specific surface area, open channels, and large cavity structure, has a good foundation for application in the adsorption and separation of environmental pollutants and CO2 capture; metal-supported M-COF materials can optimize the efficiency of photocatalytic CO2 reduction by controlling the light absorption range, charge distribution, and band structure of the catalyst through the coupling effect of active metal M and COF; electron beam irradiation can cause moderate damage to the material structure, forming defect structures on the surface, increasing the specific surface area and providing more adsorption and catalytic active sites, thereby improving the material's adsorption and photocatalytic reduction performance for CO2.

[0007] Terminology Explanation: In this invention, Btt-Bpy-COF refers to a COF synthesized from benzo[1,2-b:3,4-b':5,6-b']trithiophene-2,5,8-trialdehyde and 5,5'-diamino-2,2'-bipyridine via a Schiff base reaction. The structural formula of 5,5'-diamino-2,2'-bipyridine is: The structural formula of benzo[1,2-b:3,4-b':5,6-b']trithiophene-2,5,8-trialdehyde is: Optionally, the cobalt salt is cobalt chloride; the nickel salt is nickel chloride; and the copper salt is copper chloride.

[0008] Preferably, the mass ratio of Btt-Bpy-COF to the metal element in the active metal salt is 1:1 to 1.5.

[0009] Preferably, the reaction temperature is 60°C and the time is 12~24h.

[0010] Preferably, the volume ratio of 1,4-dioxane to 1,3,5-trimethylbenzene is 1:1.

[0011] Preferably, the electron beam irradiation dose is 105~360kGy.

[0012] The second technical solution of the present invention provides an electron beam irradiation modified active metal covalent organic framework material prepared according to the above-mentioned preparation method of electron beam irradiation modified active metal covalent organic framework material.

[0013] The third technical solution of the present invention provides an application of the above-mentioned electron beam irradiation modified active metal covalent organic framework material in photocatalytic CO2 reduction.

[0014] The beneficial technical effects of the present invention are as follows: This invention first prepares metallized COF materials, namely M-COF (where M = Co, Ni, or Cu), via a post-modification method. Based on this, it innovatively introduces an electron beam irradiation modification method to successfully construct a series of eM-COF materials. In the constructed eM-COFs, the metal active sites are stably anchored on the COF framework, and the band structure and charge separation efficiency of the material are optimized, making it suitable as a highly efficient photocatalyst for CO2 reduction. Compared with M-COF materials, eM-COF materials significantly improve the photocatalytic CO2 reduction efficiency and effectively suppress hydrogen evolution side reactions in aqueous systems. This invention effectively overcomes the technical bottlenecks of current COF-based photocatalysts in core performance indicators such as active site regulation, electronic structure optimization, and selective CO2 reduction. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 The XRD patterns are theoretical simulation and experimental XRD spectra of the raw material Btt-Bpy-COF used in this invention, as well as the XRD spectra of M-COF materials in Examples 1, 4, and 7.

[0017] Figure 2 The XRD patterns are of the photocatalysts prepared in Comparative Example 1 and Examples 1-3.

[0018] Figure 3 This is a comparison chart of the performance of the photocatalysts prepared in Comparative Example 1 and Example 1 for CO2 reduction, including the yields and total selectivity of the four CO2 reduction products (CO, CH4, C2H4 and C2H6).

[0019] Figure 4 This is a comparison chart of the performance of the photocatalysts prepared in Comparative Example 1 and Example 2 for CO2 reduction, including the yield and total selectivity of the four CO2 reduction products (CO, CH4, C2H4 and C2H6).

[0020] Figure 5 This is a comparison chart of the performance of the photocatalysts prepared in Comparative Example 1 and Example 3 for CO2 reduction, including the yield and total selectivity of the four CO2 reduction products (CO, CH4, C2H4 and C2H6).

[0021] Figure 6 The XRD patterns are those of the photocatalysts prepared in Comparative Example 2 and Examples 4-6.

[0022] Figure 7 This is a comparison chart of the performance of the photocatalysts prepared in Comparative Example 2 and Example 4 for CO2 reduction, including the yield and total selectivity of the four CO2 reduction products (CO, CH4, C2H4 and C2H6).

[0023] Figure 8 This is a comparison chart of the performance of the photocatalysts prepared in Comparative Example 2 and Example 5 for CO2 reduction, including the yield and total selectivity of the four CO2 reduction products (CO, CH4, C2H4 and C2H6).

[0024] Figure 9 This is a comparison chart of the performance of the photocatalysts prepared in Comparative Example 2 and Example 6 for CO2 reduction, including the yields and total selectivity of the four CO2 reduction products (CO, CH4, C2H4 and C2H6).

[0025] Figure 10 The XRD patterns are those of the photocatalysts prepared in Comparative Example 3 and Example 7.

[0026] Figure 11 This is a comparison chart of the performance of the photocatalysts prepared in Comparative Example 3 and Example 7 for CO2 reduction, including the yield and total selectivity of the four CO2 reduction products (CO, CH4, C2H4 and C2H6). Detailed Implementation

[0027] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0028] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0029] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0030] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0031] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0032] The Btt-Bpy-COF used in this embodiment of the invention employs a typical synthesis method, and the synthesis steps are as follows: 5,5'-diamino-2,2'-bipyridine (0.3 mmol) and benzo[1,2-b:3,4-b':5,6-b']trithiophene-2,5,8-trialdehyde (0.2 mmol) were thoroughly mixed, ground, and placed into a heat-resistant glass tube. Then, 1,4-dioxane (2.0 mL), 1,3,5-trimethylbenzene (2.0 mL), and glacial acetic acid (6.0 M, 0.2 mL) were added sequentially. The mixture was rapidly frozen at -196 °C for 30 min, followed by vacuum for at least 30 min, and the glass tube was sealed under vacuum using an oxyhydrogen flame. It was then stored in an oven at 120 °C for 72 h. After the reaction was complete, the resulting solid mass was ground and washed sequentially with dimethylformamide (DMF) and tetrahydrofuran (THF) until the centrifuged liquid was colorless. Drying at 80 °C for 12 h yields an orange-red powder, which is Btt-Bpy-COF.

[0033] Example 1 Btt-Bpy-COF (200 mg) was dispersed in 50 mL of ethanol, and CoCl2∙6H2O (1.0 g) was added, equivalent to adding 124 mg of the metal element Co per 100 mg of Btt-Bpy-COF. The mixture was reacted at 60 °C for 12 h. After the reaction was complete, the product was filtered, washed with ethanol, and centrifuged until the filtrate was colorless. The solid product was dried under vacuum at 50 °C for 12 h to obtain the M-COF material, denoted as Co-Btt-Bpy-COF.

[0034] The obtained Co-Btt-Bpy-COF (45 mg) was added to a 10 mL scintillation bottle, followed by the addition of 0.5 mL of 1,4-dioxane and 0.5 mL of 1,3,5-trimethylbenzene. The mixture was sonicated for 2 min, then sealed and purged with N2 for 2 min to remove O2. Finally, electron beam irradiation was performed at an absorbed dose of 105 kGy. The irradiated sample was washed sequentially with DMF and THF, and dried in an oven at 80 °C for 12 h to obtain the eM-COF photocatalyst, denoted as Co-Btt-Bpy-COF-105 kGy.

[0035] Example 2 Compared with Example 1, the only difference is that the absorbed dose of electron beam irradiation is adjusted to 270 kGy, and the resulting photocatalyst is denoted as Co-Btt-Bpy-COF-270 kGy.

[0036] Example 3 Compared with Example 1, the only difference is that the absorbed dose of electron beam irradiation is adjusted to 360 kGy, and the resulting photocatalyst is denoted as Co-Btt-Bpy-COF-360 kGy.

[0037] Comparative Example 1 Compared with Example 1, the only difference is that it was not irradiated with an electron beam, and the resulting photocatalyst is denoted as Co-Btt-Bpy-COF-0kGy.

[0038] Example 4 Btt-Bpy-COF (200 mg) was dispersed in 50 mL of ethanol, and NiCl2∙6H2O (1.0 g) was added, equivalent to adding 123 mg of Ni metal element per 100 mg of Btt-Bpy-COF. The mixture was reacted at 60 °C for 12 h. After the reaction was complete, the product was filtered, washed with ethanol, and centrifuged until the filtrate was colorless. The solid product was dried under vacuum at 50 °C for 12 h to obtain M-COF material, denoted as Ni-Btt-Bpy-COF.

[0039] The obtained Ni-Btt-Bpy-COF (45 mg) was added to a 10 mL scintillation bottle, followed by the addition of 0.5 mL of 1,4-dioxane and 0.5 mL of 1,3,5-trimethylbenzene. The mixture was sonicated for 2 min, then sealed and purged with N2 for 2 min to remove O2. Finally, electron beam irradiation was performed at an absorbed dose of 105 kGy. The irradiated sample was washed sequentially with DMF and THF, and dried in an oven at 80 °C for 12 h to obtain the eM-COF photocatalyst, denoted as Ni-Btt-Bpy-COF-105 kGy.

[0040] Example 5 Compared with Example 4, the only difference is that the absorbed dose of electron beam irradiation was adjusted to 180 kGy, and the resulting photocatalyst is denoted as Ni-Btt-Bpy-COF-180 kGy.

[0041] Example 6 Compared with Example 4, the only difference is that the absorbed dose of electron beam irradiation was adjusted to 360 kGy, and the resulting photocatalyst is denoted as Ni-Btt-Bpy-COF-360 kGy.

[0042] Comparative Example 2 Compared with Example 4, the only difference is that it was not irradiated with an electron beam, and the resulting photocatalyst is denoted as Ni-Btt-Bpy-COF-0kGy.

[0043] Example 7 Btt-Bpy-COF (200 mg) was dispersed in 50 mL of ethanol, and CuCl2∙2H2O (0.7 g) was added, equivalent to adding 133 mg of Cu per 100 mg of Btt-Bpy-COF. The mixture was reacted at 60 °C for 12 h. After the reaction was complete, the product was filtered, washed with ethanol, and centrifuged until the filtrate was colorless. The solid product was dried under vacuum at 50 °C for 12 h to obtain the M-COF material, denoted as Cu-Btt-Bpy-COF.

[0044] The obtained Cu-Btt-Bpy-COF (45 mg) was added to a 10 mL scintillation bottle, followed by the addition of 0.5 mL of 1,4-dioxane and 0.5 mL of 1,3,5-trimethylbenzene. The mixture was sonicated for 2 min, then sealed and purged with N2 for 2 min to remove O2. Finally, electron beam irradiation was performed at an absorbed dose of 105 kGy. The irradiated sample was washed sequentially with DMF and THF, and dried in an oven at 80 °C for 12 h to obtain the eM-COF photocatalyst, denoted as Cu-Btt-Bpy-COF-105 kGy.

[0045] Comparative Example 3 Compared with Example 7, the only difference is that it was not irradiated with an electron beam, and the resulting photocatalyst is denoted as Cu-Btt-Bpy-COF-0kGy.

[0046] Experimental procedure and conditions for photocatalytic CO2 reduction reaction: 10 mL of acetonitrile / water / triisopropanolamine (v:v:v=6:3:1) solution was added to a 182 mL quartz reactor, followed by 5.0 mg of [Ru(bpy)3]Cl2 and 1 mg of the photocatalyst prepared in each example or comparative example. The quartz reactor was purged with CO2 (1.0 bar) for 30 min and then sealed with a rubber stopper. The reaction system was irradiated with a 300 W xenon lamp equipped with a UVCUT 420 filter (λ≥420 nm). After the reaction, the composition and content of the products (including CO, CH4, C2H6, C2H4, H2) were analyzed by gas chromatography. Each experiment lasted 4 h. After each run, the solid catalyst was recovered by centrifugation and washed with acetonitrile.

[0047] In aqueous CO2 photocatalytic reduction systems, a competitive hydrogen evolution reaction often occurs. Here, the overall selectivity of the CO2 reduction reaction is used. Evaluate the advantages of CO2 reduction over the hydrogen evolution side reaction.

[0048] in, n i : Amount of product i (product i is CO, CH4, C2H4, or C2H6), in mol; R i The number of electrons required to generate this product (2 for CO, 8 for CH4, 12 for C2H4, and 14 for C2H6). : The amount of H2 produced, in mol.

[0049] The theoretical simulation and experimental XRD patterns of the raw material Btt-Bpy-COF used in this invention, as well as the XRD patterns of the M-COF materials in Examples 1, 4, and 7, are shown below. Figure 1 .

[0050] Figure 1 The results showed that all samples exhibited similar diffraction peak positions, indicating that the crystal structure of COF was maintained after metal loading, without significant structural collapse, and that it possessed high crystallinity and structural stability.

[0051] The XRD patterns of the photocatalysts prepared in Comparative Example 1 and Examples 1-3 are shown in the figure. Figure 2 .

[0052] Figure 2 The results show that as the absorbed dose of electron beam irradiation increases from 0 kGy to 360 kGy, the XRD diffraction peak intensity of Co-Btt-Bpy-COF decreases significantly and continuously, with the main peak almost disappearing at 360 kGy. This indicates that the accumulation of defects induced by the high-energy electron beam causes the material to gradually evolve from a highly crystalline state to a near-amorphous state. The slight peak shift at 105 kGy is attributed to lattice distortion and local stress generated in the early stages of irradiation; while the peak return at 270 kGy reflects the release of internal stress through structural relaxation. However, this dynamic adjustment failed to prevent the continuous loss of crystallinity, and ultimately the long-range ordered structure was destroyed at high doses.

[0053] A comparison of the performance of the photocatalysts prepared in Comparative Example 1 and Example 1 for CO2 reduction is shown below. Figure 3 .

[0054] Figure 3 The results showed that when the absorbed dose of electron beam irradiation was 105 kGy, the yield of CO produced by photocatalytic reduction of CO2 was significantly increased, reaching 4.4 mmol·g⁻¹ after 4 h. -1 This represents a 44-fold increase (comparative example 1 was only 0.1 mmol·g). -1Furthermore, the yields of hydrocarbon reduction products CH4, C2H6, and C2H4 also increased, and the overall selectivity of the CO2 reduction reaction was significantly improved. After 4 hours of reaction, = 86% (Comparative Example 1 is only 8%).

[0055] A comparison of the performance of the photocatalysts prepared in Comparative Example 1 and Example 2 for CO2 reduction is shown below. Figure 4 .

[0056] Figure 4 The results showed that when the absorbed dose of electron beam irradiation was 270 kGy, the yield of CO produced by photocatalytic reduction of CO2 was significantly increased, reaching 2.0 mmol·g⁻¹ after 4 h. -1 It increased 20-fold (comparative example 1 was only 0.1 mmol·g). -1 Furthermore, the yields of hydrocarbon reduction products CH4, C2H6, and C2H4 also increased, and the overall selectivity of the CO2 reduction reaction was significantly improved. After 4 hours of reaction, = 82% (Comparative Example 1 is only 8%).

[0057] A comparison of the performance of the photocatalysts prepared in Comparative Example 1 and Example 3 for CO2 reduction is shown in the figure. Figure 5 .

[0058] Figure 5 The results showed that when the absorbed dose of electron beam irradiation was 360 kGy, the yield of CO produced by photocatalytic CO2 reduction was significantly increased, reaching 9.8 mmol·g⁻¹ after 4 h. -1 It increased 98 times (comparative example 1 was only 0.1 mmol·g). -1 Furthermore, the reduction efficiency of hydrocarbon products CH4, C2H6, and C2H4 was also improved, and the overall selectivity of the CO2 reduction reaction was significantly increased. After 4 hours of reaction, = 88% (Comparative Example 1 is only 8%).

[0059] The XRD patterns of the photocatalysts prepared in Comparative Example 2 and Examples 4-6 are shown below. Figure 6 .

[0060] Figure 6 The results show that although electron beam irradiation weakens the XRD diffraction peak intensity of Ni-Btt-Bpy-COF, the main peak remains clearly visible even at 360 kGy, indicating that the material maintains good crystallinity throughout the irradiation process. Throughout the irradiation process, the positions of all diffraction peaks remain unchanged, indicating that the lattice parameters and long-range ordered framework structure of Ni-Btt-Bpy-COF remain stable, without lattice distortion or phase transition, exhibiting a more rigid lattice structure and excellent radiation resistance.

[0061] A comparison of the performance of the photocatalysts prepared in Comparative Example 2 and Example 4 for CO2 reduction is shown below. Figure 7 .

[0062] Figure 7 The results showed that when the absorbed dose of electron beam irradiation was 105 kGy, the yields of CO, CH4, and C2H6 produced by photocatalytic CO2 reduction were significantly increased, reaching 364 μmol·g⁻¹ after 4 h. -1 (Increased by 2.5 times, compared to 148 μmol·g in Comparative Example 2) -1 ), 259 μmol·g -1 (Increased by 3.2 times, compared to 82 μmol·g in Comparative Example 2) -1 ), 55 μmol·g -1 (This is a 5-fold increase, compared to only 11 μmol·g in Comparative Example 2) -1 Furthermore, the overall selectivity of the CO2 reduction reaction was also significantly improved; after 4 hours of reaction, = 88% (Comparative Example 2 is 61%).

[0063] A comparison of the performance of the photocatalysts prepared in Comparative Example 2 and Example 5 for CO2 reduction is shown below. Figure 8 .

[0064] Figure 8 The results showed that when the absorbed dose of electron beam irradiation was 180 kGy, the yields of CO, CH4, and C2H6 produced by photocatalytic CO2 reduction were significantly increased, reaching 525 μmol·g⁻¹ after 4 h. -1 (Increased by 3.5 times, compared to 148 μmol·g in Comparative Example 2) -1 ), 257 μmol·g -1 (Increased by 3.1 times, compared to 82 μmol·g in Comparative Example 2) -1 ), 45 μmol·g -1 (Increased by 4.1 times, compared to 11 μmol·g in Comparative Example 2) -1 Furthermore, the overall selectivity of the CO2 reduction reaction was also significantly improved; after 4 hours of reaction, =88% (Comparative Example 2 is 61%).

[0065] A comparison of the performance of the photocatalysts prepared in Comparative Example 2 and Example 6 for CO2 reduction is shown below. Figure 9 .

[0066] Figure 9 The results showed that when the absorbed dose of electron beam irradiation was 360 kGy, the yields of photocatalytic CO2 reduction to CO, CH4, and C2H6 were significantly increased, reaching 624 μmol·g⁻¹ after 4 h. -1(Increased by 4.2 times, compared to 148 μmol·g in Comparative Example 2) -1 ), 263 μmol·g -1 (Increased by 3.2 times, compared to 82 μmol·g in Comparative Example 2) -1 ), 66 μmol·g -1 (Increased by 6.0 times, compared to 11 μmol·g in Comparative Example 2) -1 Furthermore, the overall selectivity of the CO2 reduction reaction was also significantly improved; after 4 hours of reaction, = 92% (Comparative Example 2 is 61%).

[0067] The XRD patterns of the photocatalysts prepared in Comparative Example 3 and Example 7 are shown in Figure 7. Figure 10 .

[0068] Figure 10 The results show that when the absorbed dose of electron beam irradiation is 105 kGy, although the intensity of the XRD diffraction peaks of Cu-Btt-Bpy-COF is weakened, the main peak is still clearly visible and the position of the diffraction peaks has not shifted, indicating that the material has good crystallinity and radiation resistance.

[0069] A comparison of the performance of the photocatalysts prepared in Comparative Example 3 and Example 7 for CO2 reduction is shown below. Figure 11 .

[0070] Figure 11 The results showed that when the absorbed dose of electron beam irradiation was 105 kGy, the yield of CO produced by photocatalytic CO2 reduction was significantly increased, reaching 2 mmol·g⁻¹ after 4 h. -1 It increased by 2.9 times (comparative example 3 was 0.7 mmol·g). -1 Furthermore, the efficiency of photocatalytic reduction of carbon dioxide to CH4 and C2H6 products was improved, but the yield of C2H4 decreased. The overall selectivity of the CO2 reduction reaction was improved; after 4 hours of reaction, = 86% (Comparative Example 3 is 77%).

[0071] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing an electron beam irradiation modified active metal-supported covalent organic framework material, characterized in that, Includes the following steps: COF material and active metal salt are co-dispersed in a solvent, and after reaction, active metal covalent organic framework material is obtained; the active metal covalent organic framework material is dispersed in a mixed solvent of 1,4-dioxane and 1,3,5-trimethylbenzene, and then subjected to electron beam irradiation in an inert atmosphere to obtain electron beam irradiation modified active metal covalent organic framework material. The COF material is Btt-Bpy-COF; The active metal salts include: cobalt salts, nickel salts, or copper salts.

2. The method for preparing electron beam irradiation modified active metal covalent organic framework material according to claim 1, characterized in that, The cobalt salt is cobalt chloride; the nickel salt is nickel chloride; and the copper salt is copper chloride.

3. The method for preparing the electron beam irradiation modified active metal covalent organic framework material according to claim 1, characterized in that, The mass ratio of Btt-Bpy-COF to the metal element in the active metal salt is 1:1~1.

5.

4. The method for preparing electron beam irradiation modified active metal covalent organic framework material according to claim 1, characterized in that, The reaction was carried out at a temperature of 60°C for 12-24 hours.

5. The method for preparing the electron beam irradiation modified active metal covalent organic framework material according to claim 1, characterized in that, The volume ratio of 1,4-dioxane to 1,3,5-trimethylbenzene is 1:

1.

6. The method for preparing electron beam irradiation modified active metal covalent organic framework material according to claim 1, characterized in that, The electron beam irradiation dose is 105~360kGy.

7. An electron beam irradiation modified active metal covalent organic framework material prepared by the preparation method of the electron beam irradiation modified active metal covalent organic framework material according to any one of claims 1 to 6.

8. The application of the electron beam irradiation modified active metal covalent organic framework material according to claim 7 in the photocatalytic reduction of carbon dioxide.

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