Porous aromatic skeleton photocatalyst, synthesis method and application thereof

Abstract

The present application relates to the technical field of photocatalytic materials, in particular to a kind of porous aromatic skeleton photocatalyst and its synthesis method and application.Synthesis method is under inert atmosphere with thiol-containing organic monomer, alkyne-containing organic monomer and photoinitiator as raw material, under light room temperature click chemistry reaction to obtain porous aromatic skeleton photocatalyst, process mild, simple operation, yield 70%~81%.The material is a multi-level pore structure, high specific surface area, wide light response range, can be in the absence of oxygen, no sacrificial agent conditions, high efficiency drive two electron water oxidation reaction produce hydrogen peroxide.Among them, PAF-263 catalytic performance is optimal, yield reaches 4.98mmol / g·h, in continuous photoreactor stable operation is more than 84 hours without obvious attenuation, effectively inhibits four electron oxygen precipitation side reaction, provides new material and technical path for green efficient photocatalytic synthesis of hydrogen peroxide.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic materials technology, specifically to a class of porous aromatic framework photocatalysts, their synthesis methods, and applications. Background Technology

[0002] Hydrogen peroxide, or H2O2, is a versatile and environmentally friendly oxidant widely used in various industrial processes. As a key chemical, H2O2 acts as a bridge between sustainable chemistry, energy technology innovation, and industrial efficiency improvement, becoming an important component of the circular economy system. Currently, the anthraquinone process remains the main industrial process for producing hydrogen peroxide, but this method faces significant challenges in terms of economics, environmental impact, and safety. In contrast, photocatalytic water oxidation technology provides a promising solar energy conversion pathway for the synthesis of hydrogen peroxide. It can efficiently generate hydrogen peroxide directly using abundant water resources and solar energy under mild reaction conditions, demonstrating significant potential for sustainable development.

[0003] Significant progress has been made in recent years in the photocatalytic water splitting synthesis of H2O2, particularly in the two-electron oxygen reduction reaction (2e⁻ ORR). This process proceeds through two mechanisms: a continuous single-electron transfer pathway (O2→•O2⁻→H2O2) and a concerted two-electron reduction mechanism (O2 + 2H⁺). + +2e⁻→H₂O₂, with a potential of 0.695V vs. NHE. However, the large-scale application of this system is fundamentally limited by the physical properties of oxygen molecules, including their low solubility in water and slow diffusion kinetics. Continuous aeration accounts for more than 30% of the total energy consumption, with a pressure difference ΔP = 0.5 bar to 1.5 bar, while the gas-liquid mass transfer resistance significantly reduces the reaction rate. Compared to 2e⁻ ORR, the two-electron water oxidation reaction, 2e⁻ WOR, 2H₂O→H₂O₂ + 2H + The +2e⁻ reaction, with a potential of 1.76V vs. NHE, represents a promising alternative pathway. In this reaction, water molecules act as both proton donors and electron sources, potentially constructing a self-closing redox cycle for the sustainable generation of H₂O₂. However, currently, the thermodynamically more dominant four-electron oxygen evolution reaction, OER (2H₂O → O₂ + 4H⁺), remains the preferred alternative. + +4e⁻, potential of 1.23V vs. the presence of NHE, and the extremely short lifetime of the hydroxyl radical intermediate ·OH, when pH=7, τ 1 / 2 =3.2×10 -5 Furthermore, the synthesis process of existing catalytic materials is demanding, making it difficult to rely solely on the 2e⁻ WOR pathway to photocatalytically synthesize H₂O₂ when used in reactions, thus hindering the direct conversion of water to hydrogen peroxide. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a class of porous aromatic framework photocatalysts, their synthesis method, and applications. Through photoinitiation, thiol groups undergo an addition reaction with alkynyl groups to form stable carbon-sulfur bonds. The synthesis method of this invention is simple, can be carried out under mild conditions, and is easy to operate. This solves the problem that existing catalytic materials require stringent synthesis processes and cannot achieve the direct conversion of water to hydrogen peroxide.

[0005] In this invention, porous aromatic frameworks are referred to as PAFs.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The first objective of this invention is to provide a method for synthesizing a class of porous aromatic framework photocatalysts, comprising the following steps: Under an inert atmosphere and with the aid of a photoinitiator, thiol-containing organic monomers and alkynyl-containing organic monomers are dissolved in an organic solvent system and subjected to a click chemical reaction at room temperature under light irradiation. The thiol and alkynyl groups form carbon-sulfur bonds through addition, yielding a porous aromatic framework photocatalyst.

[0007] In the above synthesis process, a photoinitiated addition reaction occurs between the thiol and alkynyl groups, forming a stable carbon-sulfur bond. The core reaction mechanism is shown below:

[0008] .

[0009] In a preferred embodiment of the present invention, the thiol-containing organic monomer is 1,4-phenylenediol or 4,4'-dimercaptodiphenyl sulfide. The thiol group (-SH) in the aryl thiol has a strong electron-donating ability; the lone pair electrons of the sulfur atom can be rapidly transferred to the alkynyl acceptor site of the polyalkynyl monomer. This not only enhances the chemical stability of the thioether bond after polymerization but also promotes the polymerization reaction through DA action. The structures of 1,4-phenylenediol and 4,4'-dimercaptodiphenyl sulfide are shown below:

[0010] .

[0011] In a preferred embodiment of the present invention, the alkynyl-containing organic monomer is at least one selected from tris(4-ethynylphenyl)amine, 1,3,5-tris(4-ethynylphenyl)benzene, 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine, tetra(4-ethynylphenyl)ethylene, tetra(4-ethynylphenyl)methane, and 1,3,6,8-tetraynylpyrene. Different aromatic core structures can precisely control the pore environment and electron accepting ability of the material: for example, the tetraphenylphenyl framework can optimize the distribution of electron accepting sites; the large π-conjugated pyrene framework can enhance visible light absorption performance and improve electron capture ability; the nitrogen-centered triphenylamine framework can adjust the electron accepting intensity to adapt to different catalytic requirements; and the polar triazine framework can enhance electron accepting stability. The structures of the alkynyl-containing organic monomers are as follows:

[0012] .

[0013] In a preferred embodiment of the present invention, the photoinitiator is at least one selected from benzoin dimethyl ether, benzoyl dimethyl ketal, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, 4,6-trimethylbenzoylphosphine oxide and 2-carboxy-2-methylphenylacetone.

[0014] In a preferred embodiment of the present invention, the amount of photoinitiator is 2% to 5% of the total mass of the alkynyl-containing organic monomer and the thiol-containing organic monomer, and the molar ratio of the alkynyl-containing organic monomer to the thiol-containing organic monomer is 2:3.

[0015] In a preferred embodiment of the present invention, the illumination is sunlight, natural light, xenon lamp, LED lamp, or ultraviolet lamp.

[0016] In a preferred embodiment of the present invention, the mass-volume ratio of photoinitiator to organic solvent is 1 mg to 10 mg: 10 mL to 200 mL, more preferably 5 mg: 40 mL, and the organic solvent is at least one selected from dichloromethane, tetrahydrofuran, N,N-dimethylformamide and acetonitrile.

[0017] In a preferred embodiment of the present invention, the inert gas is nitrogen or argon.

[0018] A second objective of this invention is to provide a class of porous aromatic framework photocatalysts synthesized by the above-described method.

[0019] The photocatalyst is a novel porous aromatic framework material linked by alkenyl thioether bonds, and is a three-dimensional cross-linked porous polymer. It includes a core framework unit of polyalkynyl aromatic monomers, framework units of polythiol aromatic monomers, and framework connecting units. The framework connecting units are vinyl thioether bonds, generated in situ by click polymerization of thiol and alkyne groups. Sulfur atoms are uniformly distributed on the inner walls of the material's pores, achieving uniform introduction of functional sites without post-modification. Although patent CN118814221A discloses porous aromatic framework materials with certain pore structures and aromatic conjugation characteristics, it lacks charge transfer channels that can efficiently drive the separation and migration of photogenerated carriers, making it difficult to achieve efficient intramolecular or intermolecular charge transfer. This limits its performance in charge transfer-dependent applications such as photocatalysis and photoelectric conversion.

[0020] It should be noted that the porous aromatic framework photocatalyst has a donor-π-acceptor (D-π-A) structure, in which the electron-rich aromatic ring unit acts as the electron donor, and the electron-deficient heterocyclic or electron-withdrawing group acts as the electron acceptor, connected by a conjugated π-bridge. Under photoexcitation or an external electric field, electrons can spontaneously undergo efficient intramolecular charge transfer from the donor unit to the acceptor site, effectively narrowing the band gap, widening the light absorption range, and accelerating the separation and migration of photogenerated electron-hole pairs. The built-in electric field formed in the system can significantly suppress carrier recombination, enriching active electrons at the acceptor active site, optimizing the adsorption and desorption behavior of reaction intermediates, thereby greatly improving the photoelectric conversion efficiency and catalytic performance such as hydrogen evolution and hydrogen peroxide production.

[0021] A third objective of this invention is to provide an application of the above-mentioned porous aromatic framework photocatalyst in photocatalytic hydrogen peroxide production.

[0022] Photocatalytic hydrogen peroxide production specifically refers to the photocatalytic generation of hydrogen peroxide from water via the 2e⁻ WOR pathway, driven by photoexcitation and oxygen-free conditions. In this process, the D-π-A structure of the porous aromatic framework material is excited under light irradiation, initiating charge separation and generating holes in the acceptor region. These holes then migrate to unbound thiol groups, oxidizing them to thiol radicals, which serve as catalytic centers driving the 2e⁻ WOR reaction.

[0023] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention provides a method for synthesizing a class of porous aromatic framework photocatalysts. Under inert gas conditions, a mercapto-containing organic monomer, an alkyne-containing organic monomer, a photoinitiator, and an organic solvent are mixed, and a click chemistry reaction is initiated under light irradiation to obtain the porous aromatic framework photocatalyst. This invention utilizes photoinitiation to induce an addition reaction between mercapto and alkyne groups, forming a stable carbon-sulfur bond. The synthesis method of this invention is simple, can be carried out under mild conditions, and is easy to operate. This solves the problem that existing catalytic material synthesis processes are demanding and cannot achieve the direct conversion of water to hydrogen peroxide.

[0024] 2. This invention provides a porous aromatic framework photocatalyst, which is a three-dimensional cross-linked porous polymer with alkenyl thioether bonds. It includes a core framework unit of polyalkynyl aromatic monomers, a framework unit of polythiol aromatic monomers, and a framework connecting unit. The framework connecting unit is a vinyl thioether bond, which is generated in situ by click polymerization of thiol and alkyne groups. Sulfur atoms are distributed on the inner wall of the pores of the material, and the uniform introduction of functional sites can be achieved without post-modification.

[0025] 3. The porous aromatic framework photocatalyst provided by this invention, under light irradiation, excites the D-π-A structure, initiating charge separation and generating holes in the acceptor region. The generated holes then migrate to unbound thiol groups, oxidizing them to thiol radicals, which serve as catalytic centers to drive the 2e⁻ WOR reaction for photocatalytic water splitting to produce hydrogen peroxide.

[0026] 4. The porous aromatic framework photocatalyst synthesized in this invention can directly generate hydroxyl radicals by decomposing water with sulfur free radicals. Subsequently, two hydroxyl radicals dimerize to generate hydrogen peroxide. This method avoids multiple electron and pathway steps, thus improving the catalytic ability of the catalyst. Attached Figure Description

[0027] Figure 1 The infrared spectra of the porous aromatic framework photocatalysts synthesized in Examples 1 to 9 of this invention are shown. Figure 1 Figure a shows the infrared spectra of PAF-261N, PAF-262, and PAF-263; Figure b shows the infrared spectra of PAF-291, PAF-292, and PAF-293; and Figure c shows the infrared spectra of PAF-255, PAF-256, and PAF-257.

[0028] Figure 2 The graphs show the carbon dioxide adsorption curves of the porous aromatic framework photocatalysts synthesized in Examples 1 to 3 of this invention.

[0029] Figure 3 This is the solid-state UV-Vis diffuse reflectance spectrum of the porous aromatic framework photocatalyst powder synthesized in Example 1 of this invention. Figure 3 Figure a shows the solid-state UV-Vis diffuse reflectance spectrum, and Figure b shows the Tauc diagram.

[0030] Figure 4 These are scanning electron microscope (SEM) images of the porous aromatic framework photocatalysts synthesized in Examples 1 to 3 of this invention. Figure 4 Image a is a scanning electron microscope (SEM) image of PAF-261N, image b is a scanning electron microscope (SEM) image of PAF-262, and image c is a scanning electron microscope (SEM) image of PAF-263.

[0031] Figure 5 The graphs show the photocatalytic hydrogen peroxide performance of the porous aromatic framework photocatalysts synthesized in Examples 1 to 3 of this invention under anaerobic conditions.

[0032] Figure 6 This is a graph showing the long-term photocatalytic hydrogen peroxide performance of the porous aromatic framework photocatalyst synthesized in Example 3 of the present invention under anaerobic conditions. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] It should be noted that the technical terms used in this invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or synthesized by existing methods.

[0035] The following specific examples will provide further explanation.

[0036] In this invention, the abbreviation for benzoin dimethyl ether is DMPA, and the abbreviation for dichloromethane is DCM. The xenon lamp parameters are AM 1.5G and light irradiance of 100mW·cm. -2 .

[0037] Example 1 A method for synthesizing a porous aromatic framework photocatalyst, PAF-261N, includes the following steps: Under nitrogen protection, 43 mg (0.3 mmol) of 1,4-benzenedithiol, 70 mg (0.2 mmol) of 1,3,5-tris(4-ethynylphenyl)benzene, and 5 mg of photoinitiator DMPA were added to a two-necked flask containing 40 mL of DCM. The reaction was stirred for 20 minutes under a nitrogen atmosphere and xenon lamp irradiation, followed by filtration to obtain a pale yellow solid product, PAF-261N. To remove unreacted monomers and photoinitiator, the product was thoroughly washed with DCM and then vacuum dried at 120 °C for 12 hours, ultimately yielding a yield of 81%.

[0038] Example 2 A method for synthesizing a porous aromatic framework photocatalyst, PAF-262, includes the following steps: Under nitrogen protection, 43 mg (0.3 mmol) of 1,4-phenylenediol, 65 mg (0.15 mmol) of tetra(4-ethynylphenyl)ethylene, and 6 mg of photoinitiator DMPA were added to a two-necked flask containing 40 mL of DCM. The reaction was stirred for 20 minutes under a nitrogen atmosphere and xenon lamp irradiation, followed by filtration to obtain a pale yellow solid product, PAF-262. To remove unreacted monomers and photoinitiator, the product was thoroughly washed with DCM, ultimately yielding a 78% yield.

[0039] Example 3 A method for synthesizing a porous aromatic framework photocatalyst, PAF-263, includes the following steps: Under nitrogen protection, 43 mg (0.3 mmol) of 1,4-benzenedithiol, 45 mg (0.15 mmol) of 1,3,6,8-tetraethynylpyrene, and 5 mg of photoinitiator DMPA were added to a two-necked flask containing 40 mL of DCM. The reaction was stirred for 20 minutes under a nitrogen atmosphere and xenon lamp irradiation, followed by filtration to obtain a brown solid product, PAF-263. To remove unreacted monomers and photoinitiator, the product was thoroughly washed with DCM, ultimately yielding a 71% yield.

[0040] Example 4 A method for synthesizing a porous aromatic framework photocatalyst, PAF-291, includes the following steps: Under nitrogen protection, 75 mg (0.3 mmol) of 4,4'-dimercaptodiphenyl sulfide, 63.5 mg (0.15 mmol) of tris(4-ethynylphenyl)amine, and 7 mg of photoinitiator DMPA were added to a two-necked flask containing 40 mL of DCM. The reaction was stirred for 20 minutes under nitrogen atmosphere and xenon lamp irradiation, followed by filtration to obtain a brownish-yellow solid product, PAF-291. To remove unreacted monomers and photoinitiator, the product was thoroughly washed with DCM, ultimately yielding a 73% yield.

[0041] Example 5 A method for synthesizing a porous aromatic framework photocatalyst, PAF-292, includes the following steps: Under nitrogen protection, 75 mg (0.3 mmol) of 4,4'-dimercaptodiphenyl sulfide, 75.7 mg (0.15 mmol) of 1,3,5-tris(4-ethynylphenyl)benzene, and 7 mg of photoinitiator DMPA were added to a two-necked flask containing 40 mL of DCM. The reaction was stirred for 20 minutes under a nitrogen atmosphere and xenon lamp irradiation, followed by filtration to obtain a brown solid product, PAF-292. To remove unreacted monomers and photoinitiator, the product was thoroughly washed with DCM, ultimately yielding a 75% yield.

[0042] Example 6 A method for synthesizing a porous aromatic framework photocatalyst, PAF-293, includes the following steps: Under nitrogen protection, 75 mg (0.3 mmol) of 4,4'-dimercaptodiphenyl sulfide, 76.3 mg (0.15 mmol) of 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine, and 8 mg of photoinitiator DMPA were added to a two-necked flask containing 40 mL of DCM. The reaction was stirred for 20 minutes under a nitrogen atmosphere and xenon lamp irradiation, followed by filtration to obtain a brown solid product, PAF-293. To remove unreacted monomers and photoinitiator, the product was thoroughly washed with DCM, ultimately yielding a 70% yield.

[0043] Example 7 A method for synthesizing a porous aromatic framework photocatalyst, PAF-255, includes the following steps: Under nitrogen protection, 50 mg (0.2 mmol) of 4,4'-dimercaptodiphenyl sulfide, 85.6 mg (0.15 mmol) of tetra(4-ethynylphenyl)ethylene, and 6 mg of photoinitiator DMPA were added to a two-necked flask containing 40 mL of DCM. The reaction was stirred for 20 minutes under a nitrogen atmosphere and xenon lamp irradiation, followed by filtration to obtain a pale yellow solid product, PAF-255. To remove unreacted monomers and photoinitiator, the product was thoroughly washed with DCM, ultimately yielding a 75% yield.

[0044] Example 8 A method for synthesizing a porous aromatic framework photocatalyst, PAF-256, includes the following steps: Under nitrogen protection, 50 mg (0.2 mmol) of 4,4'-dimercaptodiphenyl sulfide, 85 mg (0.2 mmol) of tetra(4-ethynylbenzene)methane, and 6 mg of photoinitiator DMPA were added to a two-necked flask containing 40 mL of DCM. The reaction was stirred for 20 minutes under nitrogen atmosphere and xenon lamp irradiation, followed by filtration to obtain a white solid product, PAF-256. To remove unreacted monomers and photoinitiator, the product was thoroughly washed with DCM, ultimately yielding a 76% yield.

[0045] Example 9 A method for synthesizing a porous aromatic framework photocatalyst, PAF-257, includes the following steps: Under nitrogen protection, 50 mg (0.2 mmol) of 4,4'-dimercaptodiphenyl sulfide, 59 mg (0.15 mmol) of 1,3,6,8-tetraethynylpyrene, and 5 mg of photoinitiator DMPA were added to a two-necked flask containing 40 mL of DCM. The reaction was stirred for 20 minutes under a nitrogen atmosphere and xenon lamp irradiation, followed by filtration to obtain a brown solid product, PAF-257. To remove unreacted monomers and photoinitiator, the product was thoroughly washed with DCM, ultimately yielding a 70% yield.

[0046] The porous aromatic framework photocatalysts of Examples 1 to 9 were characterized in terms of structure and performance.

[0047] Figure 1 The infrared spectra of the porous aromatic framework photocatalysts synthesized in Examples 1 to 9 of this invention are shown. Figure 1 Figure a shows the infrared spectra of PAF-261N, PAF-262, and PAF-263; figure b shows the infrared spectra of PAF-291, PAF-292, and PAF-293; and figure c shows the infrared spectra of PAF-255, PAF-256, and PAF-257. Figure 1 As shown, comparing the porous aromatic framework photocatalysts synthesized in Examples 1 to 9 with their corresponding monomer infrared spectra reveals that, in the target material, the absorption peak of the ≡C—H stretching vibration associated with the alkynyl monomer is at 3271 cm⁻¹. -1 ~3274cm -1 The absorption peak of the C≡C- stretching vibration is 2100 cm⁻¹. -1 ~2110cm -1 All were significantly reduced; meanwhile, the characteristic absorption peak of -SH derived from thiol monomers at 2556 cm⁻¹ was also significantly reduced. -1 The concentration also decreased significantly, indicating that these functional groups participated in the chemical transformation during the reaction. More importantly, at approximately 1675 cm⁻¹... -1A new and distinct absorption peak appeared, which is attributed to the stretching vibration of the C=C double bond. The presence of this peak is consistent with the typical product structure of the thiol-alkynyl click chemistry reaction.

[0048] Figure 2 The images show the carbon dioxide adsorption curves of the porous aromatic framework photocatalysts synthesized in Examples 1-3 of this invention. Figure 2 As shown, the adsorption isotherm rises rapidly in the low relative pressure range (P / P0), exhibiting a significant increase in adsorption capacity, indicating the presence of abundant microporous structures in the material. Conversely, a distinct adsorption-desorption hysteresis loop appears in the higher relative pressure region, suggesting the simultaneous presence of mesoporous characteristics. Therefore, these three PAF materials possess a hierarchical pore structure with both micropores and mesopores. At 195 K, the maximum carbon dioxide adsorption capacities of PAF-261N, PAF-262, and PAF-263 are 65 cm³ / s, respectively. 3 (STP) / g, 76cm 3 (STP) / g and 58cm 3 (STP) / g. The high specific surface area and interconnected hierarchical porous system not only facilitates the diffusion and enrichment of reactant molecules, but also provides an effective transport channel for the migration of charge carriers, thereby significantly promoting the mass transfer and interfacial charge transfer processes in the photocatalytic water oxidation reaction.

[0049] Figure 3 The solid-state UV-Vis diffuse reflectance spectra of the porous aromatic framework photocatalyst powders synthesized in Examples 1-3 of this invention are shown. Figure 3 Figure a shows the solid-state UV-Vis diffuse reflectance spectrum, and figure b shows the Tauc plot. Figure 3 As shown, through Tauc plot linear extrapolation analysis, the absorption edge thresholds of the three materials, PAF-261N, PAF-262, and PAF-263, are 502 nm, 556 nm, and 732 nm, respectively. Figure 3 As shown in Figure a, the optical band gaps of PAF-261N, PAF-262, and PAF-263 are 2.83 eV, 2.48 eV, and 2.11 eV, respectively. Figure 3 As shown in Figure b, the photoresponse range of the material redshifts significantly with increasing intramolecular conjugation. Among them, PAF-263, possessing the longest π-conjugated framework structure, exhibits the strongest light absorption in the visible light region, which is beneficial for improving the generation efficiency of photogenerated carriers.

[0050] Figure 4 These are scanning electron microscope (SEM) images of the porous aromatic framework photocatalysts synthesized in Examples 1 to 3 of this invention. Figure 4 Image a is a scanning electron microscope (SEM) image of PAF-261N, image b is a scanning electron microscope (SEM) image of PAF-262, and image c is a scanning electron microscope (SEM) image of PAF-263.

[0051] Next, the porous aromatic framework photocatalysts synthesized in Examples 1-3 were applied in the photocatalytic oxidation of hydrogen peroxide. The specific process was as follows: In an oxygen-free water environment under argon protection, a xenon lamp with visible light AM 1.5G was used for irradiation. No sacrificial agents were used throughout the experiment. The concentration of the generated H2O2 was quantitatively determined using the DPD-POD method (N,N-diethyl-p-phenylenediamine-peroxidase method) combined with spectrophotometry.

[0052] Figure 5 The graphs show the photocatalytic hydrogen peroxide performance of the porous aromatic framework photocatalysts synthesized in Examples 1-3 of this invention under anaerobic conditions. Figure 5 As shown, under illumination, the amount of H2O2 generated exhibits a good linear growth trend over 4 hours with increasing reaction time, indicating that the photocatalytic process has a stable yield and strong controllability. Through slope analysis, the average H2O2 generation rates of the three porous aromatic framework photocatalysts, PAF-261N, PAF-262, and PAF-263, were calculated to be 3.4 mmol / g·h, 4.37 mmol / g·h, and 4.98 mmol / g·h, respectively. This result clearly shows that PAF-263 possesses the highest photocatalytic efficiency among the three, with its hydrogen peroxide production per unit time significantly exceeding that of the other two materials.

[0053] Figure 6 This is a graph showing the long-term photocatalytic hydrogen peroxide performance of the porous aromatic framework photocatalyst synthesized in Example 3 of this invention under anaerobic conditions. Figure 6 As shown, a reaction system with a self-made integrated semi-permeable membrane structure was used. The system included a peristaltic pump, piping, and a photoreactor, and 10 mg of PAF-263 was used as a catalyst to investigate its continuous catalytic performance. The system operated stably for over 84 hours without the need for external oxygen supply, using only three barrels of fresh, un-deoxygenated water totaling 75 L as feedstock. During this period, the H2O2 production remained stable without significant decline.

[0054] In summary, the porous aromatic framework photocatalysts synthesized in this invention can achieve photocatalytic hydrogen peroxide production under anaerobic conditions with relatively small dosage. Measurements showed that the average H₂O₂ production rates of the three porous aromatic framework photocatalysts, PAF-261N, PAF-262, and PAF-263, were 3.4 mmol / g·h, 4.37 mmol / g·h, and 4.98 mmol / g·h, respectively, and they could stably catalyze the production of hydrogen peroxide from water for over 84 hours. Therefore, the porous aromatic framework photocatalysts synthesized in this invention exhibit excellent catalytic performance in the photocatalytic production of hydrogen peroxide under anaerobic conditions.

[0055] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of this invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended scope of protection is intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of this invention.

[0056] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of protection of this invention and its equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for synthesizing a class of porous aromatic framework photocatalysts, characterized in that, Includes the following steps: Under an inert atmosphere and with the aid of a photoinitiator, thiol-containing organic monomers and alkynyl-containing organic monomers are dissolved in an organic solvent system and subjected to a click chemical reaction at room temperature under light irradiation. The thiol and alkynyl groups form carbon-sulfur bonds through addition, yielding a porous aromatic framework photocatalyst.

2. The method for synthesizing the porous aromatic framework photocatalyst according to claim 1, characterized in that, The thiol-containing organic monomers are 1,4-benzene dithiol or 4,4'-dimercaptodiphenyl sulfide.

3. The method for synthesizing the porous aromatic framework photocatalyst according to claim 1, characterized in that, The alkynyl-containing organic monomer is at least one of tris(4-ethynylphenyl)amine, 1,3,5-tris(4-ethynylphenyl)benzene, 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine, tetra(4-ethynylphenyl)ethylene, tetra(4-ethynylphenyl)methane, and 1,3,6,8-tetraynylpyrene.

4. The method for synthesizing the porous aromatic framework photocatalyst according to claim 1, characterized in that, The photoinitiator is at least one of benzoin dimethyl ether, benzoyl dimethyl ketal, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, 4,6-trimethylbenzoylphosphine oxide and 2-carboxy-2-methylphenylacetone.

5. The method for synthesizing the porous aromatic framework photocatalyst according to claim 1, characterized in that, The amount of photoinitiator used is 2% to 5% of the total mass of the alkynyl-containing organic monomer and the thiol-containing organic monomer, and the molar ratio of the alkynyl-containing organic monomer to the thiol-containing organic monomer is 2:

3.

6. The method for synthesizing the porous aromatic framework photocatalyst according to claim 1, characterized in that, The lighting can be sunlight, natural light, xenon lamps, LED lamps, or ultraviolet lamps.

7. The method for synthesizing the porous aromatic framework photocatalyst according to claim 1, characterized in that, The mass-to-volume ratio of the photoinitiator to the organic solvent is 1 mg to 10 mg: 10 mL to 200 mL, and the organic solvent is at least one of dichloromethane, tetrahydrofuran, N,N-dimethylformamide, and acetonitrile.

8. The method for synthesizing the porous aromatic framework photocatalyst according to claim 1, characterized in that, The inert gas is nitrogen or argon.

9. A class of porous aromatic framework photocatalysts, characterized in that, Synthesized using the method described in any one of claims 1 to 8.

10. The application of the porous aromatic framework photocatalyst of claim 9 in photocatalytic hydrogen peroxide production.

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