A photocatalytic material of NH2-COFs@ZnS, its preparation method and application

Abstract

The application discloses an NH2-COFS@ZnS photocatalytic material and a preparation method and application thereof. A multi-amino aromatic ligand and a multi-aldehyde aromatic ligand are combined into an NH2-COFS material through a Schiff base reaction, and the NH2-COFS material is combined with a zinc salt and a sulfur source through a hydrothermal reaction to obtain an NH2-COFS@Zn photocatalytic material. The NH2-COFS@ZnS photocatalytic material has excellent photocatalytic activity, good structural stability and reusability, can be applied to photocatalytic reduction of CO2, and has the advantages of simple preparation method, low cost and meeting industrial production.

Description

Technical Field

[0001] This invention relates to a photocatalytic material, particularly to an NH2-COFs@ZnS photocatalytic material, specifically an NH2-COFs@ZnS photocatalytic material based on COFs-confined highly dispersed ZnS, and also to its preparation method and its application in photocatalytic CO2 reduction, belonging to the field of functional polymer synthesis technology. Background Technology

[0002] Carbon dioxide (CO2) is the primary greenhouse gas causing global warming. Its excessive emissions have led to a series of global environmental problems, threatening human survival and development. Atmospheric CO2 mainly originates from the combustion of fossil fuels, accounting for approximately 40% of global CO2 emissions. Although clean energy sources are being continuously developed, fossil fuels still dominate. Therefore, achieving peak carbon neutrality by reducing fossil fuel use is difficult in the short term. On the other hand, CO2 is an abundant, green, and renewable C1 resource. Catalytically converting CO2 into chemical products such as CO, CH4, methanol, and olefins can not only reduce human dependence on fossil fuels but also effectively reduce CO2 emissions, making it a current research hotspot in chemical engineering, environment, and energy fields. The main methods for catalytic conversion of CO2 include photocatalytic conversion, thermocatalytic conversion, electrocatalytic conversion, and biocatalytic conversion. Among them, photocatalytic conversion of CO2 is favored by researchers due to its advantages such as mild conditions, simple process, and environmental friendliness. Developing highly active, highly selective, and highly stable photocatalytic systems to efficiently and rapidly convert CO2 into CO, CH4, methanol, or other chemicals is a cutting-edge scientific problem that urgently needs to be solved in the fields of resource chemistry and environmental chemistry.

[0003] Inorganic semiconductors such as metal oxides, metal sulfides, and metal nitrides are widely used in CO2 photocatalytic conversion due to their simple preparation, strong visible light absorption, and stable physicochemical properties. Furthermore, by adjusting the microstructure, surface modification, and heterostructure construction, the photoresponse range can be further broadened, electron-hole pair recombination suppressed, photocatalytic efficiency improved, and highly selective conversion of target products achieved. ZnS is a high-performance photocatalyst that has seen rapid development in recent years; however, its severe photogenerated carrier recombination results in poor photocatalytic activity, a problem that is difficult to effectively address.

[0004] Covalent organic frameworks (COFs) are porous crystalline organic materials linked by covalent bonds. Their rigid cross-linked network structure endows them with high specific surface area and abundant pores, with uniform channels and controllable size. The excellent conjugated structure of COFs can broaden the photoresponse range and exhibit high electron mobility, improving the separation efficiency of photogenerated carriers. COFs possess advantages such as the designability of organic units, the diversity and tunability of their network structures, providing possibilities for the structural design and customized functional development of photocatalytic materials. However, to date, there are no reports on amino-functionalized COFs supporting ZnS photocatalysts. Summary of the Invention

[0005] To address the shortcomings of existing inorganic semiconductor photocatalytic materials and COFs in efficiently converting CO2, the first objective of this invention is to provide an NH2-COFs@ZnS photocatalytic material. This material utilizes amino-functionalized COFs to firmly confine or encapsulate the inorganic ZnS photocatalyst within or on its nanopores, achieving a perfect composite of ZnS and COFs. Furthermore, the two are effectively coupled structurally, forming an interfacial heterojunction that synergistically enhances their photocatalytic performance. This not only promotes efficient separation of photogenerated carriers and inhibits electron-hole recombination by adjusting the microstructure and vacancy defects of ZnS, thus improving photocatalytic efficiency, but also, through the conjugated structure of the COFs support, broadens the catalyst's photoresponse range and highly disperses ZnS, altering its structure and electronic properties to improve CO2 reduction activity. Simultaneously, the interfacial coupling between the two further reduces the barrier to interfacial electron transfer, accelerating the separation of photogenerated carriers and improving the catalyst's photocatalytic performance.

[0006] The second objective of this invention is to provide a method for preparing NH2-COFs@ZnS photocatalytic materials. This method allows for arbitrary control of the catalytic active sites and band gap structure, enabling it to meet the requirements of photocatalytic CO2 reduction applications. Furthermore, the preparation method is simple to operate, low in cost, and suitable for industrial production.

[0007] The three objectives of this invention are to provide an application of NH2-COFs@ZnS photocatalytic material in the photocatalytic reduction of CO2, which exhibits selectivity for the catalytic conversion of carbon dioxide to carbon monoxide, with a CO yield >10 μmol·g. -1 ·h -1 It is far superior to single ZnS and COFs materials, and this catalytic material can be reused multiple times with good reusability.

[0008] To achieve the above-mentioned technical objectives, this invention provides a method for preparing NH2-COFs@ZnS photocatalytic materials. The method involves synthesizing NH2-COFs materials by reacting polyamino aromatic ligands and polyaldehyde aromatic ligands with a Schiff base reaction, and then reacting the NH2-COFs materials with zinc salt and a sulfur source via a hydrothermal reaction to obtain the final product.

[0009] This invention utilizes polyamino aromatic ligands and polyaldehyde aromatic ligands to construct COFs materials through Schiff base reactions between amino and aldehyde groups. The resulting COFs material framework and surface are modified with amino groups, which can adsorb zinc ions through coordination. This allows for the in-situ generation of zinc sulfide on the COFs material framework and surface during the hydrothermal reaction, achieving a perfect composite of zinc sulfide and COFs. ZnS and COFs form an interfacial heterojunction, synergistically enhancing their catalytic performance. This not only promotes efficient separation of photogenerated carriers and inhibits electron-hole recombination by utilizing the microstructure and vacancy defects of ZnS, thus improving catalytic efficiency, but also broadens the photoresponse range of the catalyst by utilizing the conjugated structure of the COFs support and achieves high dispersion of ZnS, altering the structure and electronic properties of ZnS and improving CO2 reactivity. Furthermore, the interfacial coupling between the two further reduces the barrier to interfacial electron transfer, accelerates the separation of photogenerated carriers, and improves the catalytic performance of the catalyst. In addition, COFs materials have a high specific surface area and well-developed pore structure, which not only fully exposes the photocatalytic active sites inside, but also their special pore structure is conducive to the adsorption and mass transfer of carbon dioxide, thus synergistically improving the photocatalytic conversion efficiency of carbon dioxide.

[0010] As a preferred embodiment, the polyamino aromatic ligand includes at least one of p-phenylenediamine, 2,4,6-tris(aminophenyl)-1,3,5-triazine, and 1,3,5-tris(aminophenyl)benzene. Preferred polyamino aromatic ligands are common diamino aromatic ligands or triamino aromatic ligands in the prior art. The topology, pore structure, and modification positions of the amino groups in the COFs material can be adjusted by selecting polyamino aromatic ligands with different amino contents. The most preferred polyamino aromatic ligands are 2,4,6-tris(aminophenyl)-1,3,5-triazine and / or 1,3,5-tris(aminophenyl)benzene.

[0011] As a preferred embodiment, the polyaldehyde aromatic ligand includes at least one of 2,5-dibromo-terephthalaldehyde, 2,5-dimethoxy-terephthalaldehyde, 2,5-dihydroxy-terephthalaldehyde, terephthalaldehyde, 2-hydroxy-1,3,5-benzenetrialdehyde, 2,4-dihydroxy-1,3,5-pyromellitic trialdehyde, and trialdehyde-resorcinol. The preferred polyaldehyde aromatic ligand is a common dialdehyde aromatic ligand or a trialdehyde aromatic ligand in the prior art. The choice of polyaldehyde aromatic ligand is primarily used to adjust the topology and pore structure of the COFs material. Furthermore, modifying the benzene ring with common small-molecule substituents can further adjust its pore structure and polarity.

[0012] As a preferred embodiment, the molar ratio of the polyamino aromatic ligand to the polyaldehyde aromatic ligand is 1.2 to 2:1. The proportion of the polyamino aromatic ligand relative to the polyaldehyde aromatic ligand is appropriately excessive, primarily to ensure that while successfully constructing structurally stable COF materials, an appropriate amount of amino groups are modified on the framework and surface of the COF materials. These amino groups are used for ZnS composites. Specifically, for example, the molar ratio of the polyamino aromatic ligand to the polyaldehyde aromatic ligand is 1.2:1, 1.5:1, or 2:1, etc.

[0013] In the synthesis of the NH2-COFs@ZnS photocatalytic material of the present invention, by selecting the types of polyamino aromatic ligands and polyaldehyde aromatic ligands, and by utilizing the different spatial positions and numbers of substituents in the ligands, the microstructure, pore structure and interfacial band structure of the photocatalytic hybrid material NH2-COFs@ZnS can be directionally and effectively controlled.

[0014] As a preferred embodiment, the Schiff base reaction is carried out at a temperature of 20–120°C for 72–96 hours. As a more preferred embodiment, an acid solution is used as a catalyst in the Schiff base reaction, preferably acetic acid solution. The amount of acetic acid solution used is the catalytic amount. The concentration of the acetic acid solution is 3–12 mol / L. The Schiff base reaction is carried out in at least one solvent selected from dioxane, mesitylene, o-dichlorobenzene, n-butanol, and acetonitrile. The Schiff base reaction proceeds smoothly at room temperature; however, appropriately increasing the temperature can accelerate the reaction rate. A further preferred reaction temperature is 80–120°C.

[0015] As a preferred embodiment, the ratio of the NH2-COFs material to the zinc salt and sulfur source is measured according to a mass ratio of NH2-COFs material to generated ZnS of 1 to 4:10. If the proportion of generated zinc sulfide is too high, the excess zinc sulfide is difficult to stably load on the COFs material, which will reduce the stability of the material and may cause agglomeration, resulting in insufficient utilization of the active ingredients and clogging of the pore structure of the COFs material. Conversely, if the proportion of generated zinc sulfide is too low, the catalytic effect will be reduced. More preferably, the ratio of NH2-COFs material to zinc salt and sulfur source is measured according to a mass ratio of NH2-COFs material to generated ZnS of 1:10, 1:5, 3:10, or 2:5.

[0016] As a preferred embodiment, the hydrothermal reaction is performed at 100–120°C for 12–24 hours. Under these preferred hydrothermal conditions, in-situ generation of zinc sulfide nanoparticles at the amino sites of the COF material can be promoted. A dispersant (e.g., gum arabic) can be added to the hydrothermal reaction to prevent the agglomeration of the zinc sulfide nanoparticles. The zinc salt used in this invention is a common water-soluble zinc salt, preferably zinc acetate dihydrate. The sulfur source is preferably thiourea, which readily decomposes during the hydrothermal process.

[0017] The present invention also provides an NH2-COFs@ZnS photocatalytic material, which is obtained by the preparation method described above.

[0018] As a preferred embodiment, the specific surface area of ​​the NH2-COFs@ZnS photocatalytic material is 700–1600 m². 2 / g, pore volume 0.5~1.0cm 3 / g, with an average pore size of 1.0–4.0 nm, an ultraviolet-visible absorption range of >500 nm, and a band gap of <2.6 eV.

[0019] The NH2-COFs@ZnS photocatalytic material of the present invention has a stable chemical structure, which can be repeatedly subjected to multiple catalytic reactions without changing the chemical structure, thus reducing its application cost. In addition, it has good photocatalytic reduction performance for CO2, and can efficiently convert carbon dioxide into carbon monoxide, showing broad application prospects in the field of photocatalytic CO2 reduction.

[0020] This invention also provides an application of NH2-COFs@ZnS photocatalytic material, which is used for the photocatalytic reduction of CO2, particularly for the catalytic reduction of carbon dioxide to carbon monoxide.

[0021] The specific catalytic process is as follows: the photocatalyst is cast into a film, the catalyst film is placed in a reactor, and after venting, Ar gas is injected into the reactor, followed by the introduction of CO2 into the reactor. Finally, a light source is introduced at the top of the reactor, and the temperature of the reaction system is controlled at 5°C using cooling water.

[0022] This invention yields an NH2-COFs@ZnS photocatalytic material that exhibits excellent performance in photocatalytic CO2 reduction, achieving a yield of 11.3 μmol·g⁻¹. -1 ·h -1 The CO yield is high, and the photocatalytic hybrid material can be reused multiple times with good reusability.

[0023] The synthesis method of the NH2-COFs@ZnS photocatalytic material of the present invention includes the following specific steps:

[0024] Using NH2-COFs as a carrier and ZnS as a photocatalyst, a hydrothermal reaction was employed to grow ZnS on the NH2-COFs surface in one step via the interaction between -NH2 and Zn, resulting in NH2-COFs@ZnS photocatalytic material for CO2 photocatalytic conversion. The specific steps are as follows: Zinc acetate dihydrate was fully dissolved in 5 mL of water, and NH2-COFs material fully swollen in ethanol was added. The mixture was thoroughly mixed, ultrasonically dispersed, and stirred for 2 h. Thiourea and gum arabic were added to the above NH2-COFs-containing solution, and ultrasonic dispersion and stirring were continued for 1 h to form a homogeneous suspension. The stirred solution was transferred to a high-pressure reactor and reacted at 120 °C for 12 h. After cooling to room temperature, the mixture was filtered and washed several times alternately with ethanol and water. The filtered solid was then dried in a vacuum oven at 70 °C for 24 h to obtain the NH2-COFs@ZnS photocatalytic material. The NH2-COF material is simply synthesized using polyamino aromatic ligands and polyaldehyde aromatic ligands via a Schiff base reaction. The polyamino aromatic ligands are at least one of p-phenylenediamine, 2,4,6-tris(aminophenyl)-1,3,5-triazine, and 1,3,5-tris(aminophenyl)benzene; the polyaldehyde aromatic ligands are at least one of 2,5-dibromo-terephthalaldehyde, 2,5-dimethoxy-terephthalaldehyde, 2,5-dihydroxy-terephthalaldehyde, terephthalaldehyde, 2-hydroxy-1,3,5-benzenetrialdehyde, 2,4-dihydroxy-1,3,5-pyromellitic trialdehyde, and trialdehyde-resorcinol; the solvent used for the Schiff base reaction is at least one of dioxane, mesitylene, o-dichlorobenzene, n-butanol, and acetonitrile; the Schiff base reaction catalyst is a 3-12 mol / L acetic acid solution, used in an amount of 5-10% of the solvent volume; the BET specific surface area of ​​the prepared NH2-COFs@ZnS photocatalyst is 700-1600 m². 2 / g, pore volume 0.5~1.0cm 3 / g, with an average pore size of 1.0–4.0 nm.

[0025] Compared with the prior art, the technical solution of the present invention brings the following beneficial technical effects:

[0026] 1) The technical solution of this invention can construct NH2-COFs materials with different substituents by selecting different types and amounts of polyamino aromatic ligands and polyaldehyde aromatic ligands. Then, through chemical action, the ZnS photocatalyst is firmly confined or encapsulated within or on the surface of the nanopores of the NH2-COFs material. The effective coupling of the ZnS and COFs structures generates an interfacial heterojunction, synergistically enhancing its catalytic performance. On the one hand, the efficient separation of photogenerated carriers can be promoted and the recombination of electron-hole pairs suppressed by adjusting the microstructure and vacancy defects of ZnS, thereby improving catalytic efficiency. On the other hand, the conjugated structure of the COFs support not only broadens the photoresponse range of the catalyst but also highly disperses ZnS, altering its structure and electronic properties, and improving CO2 reactivity. Simultaneously, the interfacial coupling between the two further reduces the barrier to interfacial electron transfer, accelerates the separation of photogenerated carriers, improves the catalytic performance of the catalyst, and significantly enhances CO2 catalytic activity and product selectivity. In addition, COFs materials have a high specific surface area and well-developed pore structure, which not only fully exposes the photocatalytic active sites inside, but also their special pore structure is conducive to the adsorption and mass transfer of carbon dioxide, thus synergistically improving the photocatalytic conversion efficiency of carbon dioxide.

[0027] 2) The NH2-COFs@ZnS photocatalytic material of the present invention can be used multiple times after photocatalytic reduction of CO2. It has good reusability, stable structure, and can be practically applied in the field of photocatalytic CO2 reduction.

[0028] 3) The method for preparing the NH2-COFs@ZnS photocatalytic material by the present invention is simple, low in cost, and can be industrialized. Attached Figure Description

[0029] 【 Figure 1 [Image caption: High-resolution transmission electron microscopy image of the NH2-Br-COFs@ZnS-20% photocatalytic material prepared in Example 2 of this invention.]

[0030] 【 Figure 2 [Image caption: Infrared spectra of the NH2-Br-COFs@ZnS photocatalytic materials prepared in Examples 1-3 of this invention.]

[0031] 【 Figure 3 [Image showing N2 adsorption-desorption curves and pore size distribution of the NH2-Br-COFs@ZnS-20% photocatalytic material prepared in Example 2 of this invention.]

[0032] 【 Figure 4 [Image caption: X-ray powder diffraction pattern of the NH2-Br-COFs@ZnS-20% photocatalytic material prepared in Example 2 of this invention.]

[0033] 【 Figure 5[Image showing photocurrent response diagrams of the NH2-Br-COFs@ZnS-20% photocatalytic materials prepared in Examples 1-3 of this invention.]

[0034] 【 Figure 6 [Image caption: Electrochemical impedance spectroscopy of the NH2-Br-COFs@ZnS-20% photocatalytic materials prepared in Examples 1-3 of this invention.]

[0035] 【 Figure 7 [Image showing the solid-state UV spectrum and (Ahν) of the NH2-Br-COFs@ZnS-20% photocatalytic material prepared in Example 2 of this invention] 2 The graph shows the relationship between photon energy (hν) and its variation.

[0036] 【 Figure 8 [Ahν] refers to the NH2-Br-COFs@ZnS-20% photocatalytic material prepared in Example 2 of this invention. 2 The graph shows the relationship between photon energy (hν) and its variation.

[0037] 【 Figure 9 [Image showing the photocatalytic CO2 reduction performance of the NH2-Br-COFs@ZnS photocatalytic materials prepared in Examples 1-3 of this invention]

[0038] 【 Figure 10 [Structure diagrams of aldehyde and amino monomers of NH2-COFs] Detailed Implementation

[0039] The following examples are intended to further illustrate the present invention, and not to limit the scope of protection of the claims of the present invention.

[0040] Example 1

[0041] Preparation of NH2-Br-COFs@ZnS-10% photocatalytic material:

[0042] 0.15 mmol of 2,5-dibromo-terephthalaldehyde and 0.12 mmol of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine were completely dissolved in a glass vial containing 3.0 mL of dioxane. The solution was sonicated for 60 min to form a clear, transparent solution. 0.3 mL of 3.0 mol / L acetic acid was then added, and the solution was sonicated for 2 min. The vial was sealed after three cycles of freezing-vacuum-thawing in a liquid nitrogen bath. The solution was then allowed to stand at 120 °C for 72 h. After cooling to room temperature, the solution was washed several times with tetrahydrofuran, acetone, and methanol. The solution was then purified for 24 h using a Soxhlet extractor with a mixture of tetrahydrofuran and methanol. After vacuum drying at 60 °C for 24 h, the solution was collected to obtain NH₂-Br-COFs. 9.1 mg of zinc acetate dihydrate was completely dissolved in water. Then, 40 mg of NH₂-Br-COFs, fully swollen with ethanol, was added to the above solution. The solution was sonicated and stirred thoroughly for 2 h. 3.8 mg of thiourea and 3.5 mg of gum arabic were added to the above mixed solution containing NH2-Br-COFs. The mixture was then ultrasonically dispersed and stirred for 1 hour to form a homogeneous suspension. The stirred solution was transferred to a high-pressure reactor and reacted at 120°C for 12 hours. After cooling to room temperature, the mixture was filtered and washed several times alternately with ethanol and water. The filtered solid was then dried in a vacuum oven at 70°C for 24 hours to obtain the NH2-Br-COFs@ZnS-10% photocatalytic material. Infrared characterization was performed as follows. Figure 2 As shown, the aldehyde group (1690 cm⁻¹) in the NH₂-Br-COFs monomer... -1 ) and amino (3208-3319cm) -1 The disappearance of the characteristic peaks indicates that all aldehyde and amino groups in the NH2-Br-COFs monomer have been consumed, signifying the successful synthesis of NH2-Br-COFs. When ZnS is supported on the surface of NH2-Br-COFs, the photocatalytic material simultaneously contains all the characteristic peaks of both ZnS and NH2-Br-COFs, indicating a successful reaction. The prepared NH2-Br-COFs@ZnS-10% has a specific surface area of ​​up to 1562 m². 2 / g, pore volume is 1.00cm³ 3 ·g -1 It has a visible light absorption range of 520 nm and a band gap of 2.53 eV.

[0043] The photocatalytic performance was tested according to the method in Example 10: the CO yield in the photocatalytic CO2 reduction of the NH2-Br-COFs@ZnS-10% photocatalytic material prepared in Example 1 was 7.93 μmol·g. -1 ·h -1 Example 1: Preparation of NH2-Br-COFs@ZnS-10% photocatalyst material. After 5 cycles, the CO yield was 7.35 μmol·g. -1 ·h-1 In practical applications, this photocatalytic material can be reused multiple times.

[0044] Example 2

[0045] Preparation of NH2-Br-COFs@ZnS-20% photocatalytic material:

[0046] 0.15 mmol of 2,5-dibromo-terephthalaldehyde and 0.12 mmol of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine were completely dissolved in a glass vial containing 3.0 mL of dioxane. The solution was sonicated for 60 min to form a clear, transparent solution. 0.3 mL of 3.0 mol / L acetic acid was then added, and the solution was sonicated for 2 min. The vial was sealed after three cycles of freezing-vacuum-thawing in a liquid nitrogen bath. The solution was then placed at 120 °C for 72 h. After cooling to room temperature, the solution was washed several times with tetrahydrofuran, acetone, and methanol. The solution was then purified using a Soxhlet extractor with tetrahydrofuran and methanol for 24 h. After vacuum drying at 60 °C for 24 h, the solution was collected to obtain NH₂-Br-COFs. 18.1 mg of zinc acetate dihydrate was completely dissolved in water. Then, 40 mg of NH₂-Br-COFs, fully swollen with ethanol, was added to the above solution. The solution was sonicated and stirred thoroughly for 2 h. 7.5 mg of thiourea and 6.9 mg of gum arabic were added to the above mixed solution containing NH2-Br-COFs. The mixture was then ultrasonically dispersed and stirred for 1 hour to form a homogeneous suspension. The stirred solution was transferred to a high-pressure reactor and reacted at 120 °C for 12 hours. After cooling to room temperature, the mixture was filtered and washed several times alternately with ethanol and water. The filtered solid was then dried in a vacuum oven at 70 °C for 24 hours to obtain the NH2-Br-COFs@ZnS-20% photocatalytic material. Infrared characterization was performed as follows. Figure 2 As shown, the aldehyde group (1690 cm⁻¹) in the NH₂-Br-COFs monomer... -1 ) and amino (3208-3319cm) -1 The disappearance of the characteristic peaks indicates that all aldehyde and amino groups in the NH2-Br-COFs monomer have been consumed, signifying the successful synthesis of NH2-Br-COFs. When ZnS is supported on the surface of NH2-Br-COFs, the photocatalytic material simultaneously contains all the characteristic peaks of both ZnS and NH2-Br-COFs, indicating a successful reaction. The prepared NH2-Br-COFs@ZnS-20% has a specific surface area of ​​up to 1343 m². 2 / g, pore volume is 0.98cm³ 3 ·g -1 It has a visible light absorption range of 520 nm and a band gap of 2.53 eV.

[0047] The photocatalytic performance was tested according to the method in Example 10: the CO yield in the photocatalytic CO2 reduction of the NH2-Br-COFs@ZnS-20% photocatalytic material prepared in Example 2 was 11.24 μmol·g. -1 ·h -1 The NH2-Br-COFs@ZnS-20% photocatalyst material prepared in Example 2 achieved a CO yield of 10.95 μmol·g after 5 cycles. -1 ·h -1 In practical applications, this photocatalytic material can be reused multiple times.

[0048] Example 3

[0049] Preparation of NH2-Br-COFs@ZnS-30% photocatalytic material:

[0050] 0.15 mmol of 2,5-dibromo-terephthalaldehyde and 0.12 mmol of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine were completely dissolved in a glass vial containing 3.0 mL of dioxane. The solution was sonicated for 60 min to form a clear, transparent solution. 0.3 mL of 3.0 mol / L acetic acid was then added, and the solution was sonicated for 2 min. The vial was sealed after three cycles of freezing-vacuum-thawing in a liquid nitrogen bath. The solution was then placed at 120 °C for 72 h. After cooling to room temperature, the solution was washed several times with tetrahydrofuran, acetone, and methanol. The solution was then purified using a Soxhlet extractor with tetrahydrofuran and methanol for 24 h. After vacuum drying at 60 °C for 24 h, the solution was collected to obtain NH2-Br-COFs. 36.2 mg of zinc acetate dihydrate was completely dissolved in water. Then, 40 mg of NH2-Br-COFs, fully swollen with ethanol, was added to the above solution. The solution was then sonicated and stirred thoroughly for 2 h. 15.0 mg of thiourea and 13.7 mg of gum arabic were added to the above mixed solution containing NH2-Br-COFs. The mixture was then ultrasonically dispersed and stirred for 1 hour to form a homogeneous suspension. The stirred solution was transferred to a high-pressure reactor and reacted at 120 °C for 12 hours. After cooling to room temperature, the mixture was filtered and washed several times alternately with ethanol and water. The filtered solid was then dried in a vacuum oven at 70 °C for 24 hours to obtain the NH2-Br-COFs@ZnS-30% photocatalytic material. Infrared characterization was performed as follows. Figure 2 As shown, the aldehyde group (1690 cm⁻¹) in the NH₂-Br-COFs monomer... -1 ) and amino (3208-3319cm) -1The disappearance of the characteristic peaks indicates that all aldehyde and amino groups in the NH2-Br-COFs monomer have been consumed, signifying the successful synthesis of NH2-Br-COFs. When ZnS is supported on the surface of NH2-Br-COFs, the photocatalytic material simultaneously contains all the characteristic peaks of both ZnS and NH2-Br-COFs, indicating a successful reaction. The prepared NH2-Br-COFs@ZnS-30% has a specific surface area of ​​up to 1225 m². 2 / g, pore volume is 0.93cm³ 3 ·g -1 It has a visible light absorption range of 520 nm and a band gap of 2.53 eV.

[0051] The photocatalytic performance was tested according to the method in Example 10: the CO yield in the photocatalytic CO2 reduction of the NH2-Br-COFs@ZnS-30% photocatalytic material prepared in Example 3 was 7.14 μmol·g. -1 ·h -1 The NH2-Br-COFs@ZnS-30% photocatalyst material prepared in Example 3 achieved a CO yield of 6.95 μmol·g after 5 cycles. -1 ·h -1 In practical applications, this photocatalytic material can be reused multiple times.

[0052] Example 4

[0053] Preparation of NH2-OH-COFs@ZnS-20% photocatalytic material:

[0054] 0.15 mmol of 2,5-dihydroxyterephthalaldehyde and 0.12 mmol of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine were completely dissolved in a glass vial containing 3.0 mL of a mixture of dichlorobenzene and n-butanol (1:4). The solution was sonicated for 90 min to form a homogeneous mixture. Then, 0.3 mL of 3.0 mol / L acetic acid was added, and the solution was sonicated for 2 min. After three cycles of freezing-vacuum-thawing in a liquid nitrogen bath, the vial was sealed. The solution was then allowed to stand at 120 °C for 72 h. After cooling to room temperature, the solution was washed several times with tetrahydrofuran and methanol, and then purified using a Soxhlet extractor with tetrahydrofuran and methanol for 24 h. The solution was then dried under vacuum at 60 °C for 24 h and collected to obtain NH₂-OH-COFs. 18.1 mg of zinc acetate dihydrate was fully dissolved in water. Then, 40 mg of NH₂-OH-COFs, fully swollen with ethanol, was added to the above solution, and the mixture was ultrasonically dispersed and stirred thoroughly for 2 hours. 7.5 mg of thiourea and 6.9 mg of gum arabic were added to the above mixed solution containing NH₂-OH-COFs, and the mixture was ultrasonically dispersed and stirred for another 1 hour to form a homogeneous suspension. The stirred mixture was transferred to a high-pressure reactor and reacted at 120°C for 12 hours. After cooling to room temperature, the mixture was filtered and washed several times alternately with ethanol and water. The filtered solid was dried in a vacuum oven at 70°C for 24 hours to obtain NH₂-OH-COFs@ZnS-20% photocatalytic material. Infrared characterization showed that the aldehyde group (1690 cm⁻¹) in the NH₂-OH-COFs monomer... -1 ) and amino (3208-3319cm) -1 The disappearance of the characteristic peaks indicates that all aldehyde and amino groups in the NH2-OH-COFs monomer have been consumed, signifying successful synthesis of NH2-OH-COFs. When ZnS is supported on the surface of NH2-OH-COFs, the photocatalytic material simultaneously contains all the characteristic peaks of both ZnS and NH2-OH-COFs, indicating a successful reaction. The prepared NH2-OH-COFs@ZnS-20% has a specific surface area of ​​up to 875 m². 2 / g, pore volume is 0.83cm³ 3 ·g -1 It has a visible light absorption range of 600 nm and a band gap of 2.1 eV.

[0055] The photocatalytic performance was tested according to the method in Example 10: the CO yield in the photocatalytic CO2 reduction of the NH2-OH-COFs@ZnS-20% photocatalytic material prepared in Example 4 was 9.35 μmol·g. -1 ·h -1 The NH2-OH-COFs@ZnS-20% photocatalyst material prepared in Example 4 achieved a CO yield of 9.12 μmol·g after 5 cycles. -1 ·h -1In practical applications, this photocatalytic material can be reused multiple times.

[0056] Example 5

[0057] Preparation of NH2-OCH3-COFs@ZnS-20% photocatalytic material:

[0058] 0.15 mmol of 2,5-dimethoxyterephthalaldehyde and 0.12 mmol of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine were completely dissolved in a glass vial containing 3.0 mL of a mixture of dichlorobenzene and n-butanol (1:4). The solution was sonicated for 60 min to form a homogeneous mixture. 0.3 mL of 3.0 mol / L acetic acid was then added, and the solution was sonicated for 2 min. The vial was sealed after three cycles of freezing-vacuum-thawing in a liquid nitrogen bath. The solution was then placed at 120 °C for 72 h. After cooling to room temperature, the vials were washed several times with tetrahydrofuran, acetone, and methanol. The solution was then purified using a Soxhlet extractor with tetrahydrofuran and methanol for 24 h. After vacuum drying at 60 °C for 24 h, the NH₂-OCH₃-COFs were collected. 18.1 mg of zinc acetate dihydrate was fully dissolved in water. Then, 40 mg of NH₂-OCH₃-COFs, fully swollen with ethanol, was added to the above solution, and the mixture was ultrasonically dispersed and stirred thoroughly for 2 hours. 7.5 mg of thiourea and 6.9 mg of gum arabic were added to the above mixed solution containing NH₂-OCH₃-COFs, and the mixture was ultrasonically dispersed and stirred for another 1 hour to form a homogeneous suspension. The stirred solution was transferred to a high-pressure reactor and reacted at 120°C for 12 hours. After cooling to room temperature, the mixture was filtered and washed several times alternately with ethanol and water. The filtered solid was dried in a vacuum oven at 70°C for 24 hours to obtain NH₂-OCH₃-COFs@ZnS-20% photocatalytic material. Infrared characterization showed that the aldehyde group (1690 cm⁻¹) in the NH₂-OCH₃-COFs monomer... -1 ) and amino (3208-3319cm) -1 The disappearance of the characteristic peaks indicates that all the aldehyde and amino groups in the NH2-OCH3-COFs monomer have been consumed, and NH2-OCH3-COFs have been successfully synthesized. When ZnS is supported on the surface of NH2-OCH3-COFs, the photocatalytic material simultaneously contains all the characteristic peaks of both ZnS and NH2-OCH3-COFs, indicating a successful reaction. The prepared NH2-OCH3-COFs@ZnS-20% has a specific surface area of ​​up to 745 m². 2 / g, pore volume is 0.78cm³ 3 ·g -1 It has a visible light absorption range of 575 nm and a band gap of 2.6 eV.

[0059] The photocatalytic performance was tested according to the method in Example 10: the CO yield in the photocatalytic CO2 reduction of the NH2-OCH3-COFs@ZnS-20% photocatalytic material prepared in Example 5 was 10.35 μmol·g. -1 ·h -1 The NH2-OCH3-COFs@ZnS-20% photocatalyst material prepared in Example 5 achieved a CO yield of 10.1 μmol·g after 5 cycles. -1 ·h -1 In practical applications, this photocatalytic material can be reused multiple times.

[0060] Example 6

[0061] Preparation of NH2-COFs@ZnS-20% photocatalytic material:

[0062] 0.15 mmol of terephthalaldehyde and 0.12 mmol of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine were completely dissolved in a glass vial containing 3.0 mL of a 1:9 mixture of dioxane and mesitylene. The vial was sonicated for 90 min to form a homogeneous suspension. 0.3 mL of 6.0 mol / L acetic acid was then added, and the suspension was sonicated for 2 min. The vial was sealed after three cycles of freezing-vacuum-thawing in a liquid nitrogen bath. The suspension was then allowed to stand at 120 °C for 72 h. After cooling to room temperature, the vial was washed several times with tetrahydrofuran and acetone, and then purified using a Soxhlet extractor with tetrahydrofuran and methanol for 24 h. The NH₂-COFs were collected after vacuum drying at 60 °C for 24 h. 18.1 mg of zinc acetate dihydrate was completely dissolved in water. 40 mg of NH₂-COFs, fully swollen with ethanol, was then added to the above solution. The mixture was sonicated and stirred thoroughly for 2 h. 7.5 mg thiourea and 6.9 mg gum arabic were added to the above mixed solution containing NH2-COFs, and the mixture was further ultrasonically dispersed and stirred for 1 h to form a homogeneous suspension. The stirred mixed solution was transferred to a high-pressure reactor and reacted at 120 °C for 12 h. After cooling to room temperature, the mixture was filtered and washed several times with alternating ethanol and water. The filtered solid was dried in a vacuum oven at 70 °C for 24 h to obtain NH2-COFs@ZnS-20% photocatalytic material. Infrared characterization showed that the aldehyde group (1690 cm⁻¹) in the NH2-COFs monomer... -1 ) and amino (3208-3319cm) -1 The disappearance of the characteristic peaks indicates that all aldehyde and amino groups in the NH2-COFs monomers have been consumed, signifying successful synthesis of NH2-COFs. When ZnS is supported on the surface of NH2-COFs, the photocatalytic material simultaneously contains all the characteristic peaks of both ZnS and NH2-COFs, indicating a successful reaction. The prepared NH2-COFs@ZnS-20% has a specific surface area of ​​up to 856 m².2 / g, pore volume is 0.84cm³ 3 ·g -1 It has a visible light absorption range of 585nm and a band gap of 2.3eV.

[0063] The photocatalytic performance was tested according to the method in Example 10: the CO yield in the photocatalytic CO2 reduction of the NH2-COFs@ZnS-20% photocatalytic material prepared in Example 6 was 10.64 μmol·g. -1 ·h -1 The NH2-COFs@ZnS-20% photocatalyst material prepared in Example 6 achieved a CO yield of 10.35 μmol·g after 5 cycles. -1 ·h -1 In practical applications, this photocatalytic material can be reused multiple times.

[0064] Example 7

[0065] Preparation of Ph-NH2-Br-COFs@ZnS-20% photocatalytic material:

[0066] 0.15 mmol of 2,5-dibromo-terephthalaldehyde and 0.12 mmol of 1,3,5-tris(aminophenyl)benzene were completely dissolved in a glass vial containing 3.0 mL of dioxane. The solution was sonicated for 60 min to form a homogeneous suspension. 0.3 mL of 6.0 mol / L acetic acid was then added, and the suspension was sonicated for 2 min. The vial was sealed after three cycles of freezing-vacuum-thawing in a liquid nitrogen bath. It was then placed at 120 °C for 72 h. After cooling to room temperature, the vial was washed several times with tetrahydrofuran, acetone, and methanol. It was then purified using a Soxhlet extractor with tetrahydrofuran and methanol for 24 h. After vacuum drying at 60 °C for 24 h, the solution was collected to obtain Ph-NH2-Br-COFs. 18.1 mg of zinc acetate dihydrate was completely dissolved in water. Then, 40 mg of Ph-NH2-Br-COFs, fully swollen with ethanol, was added to the above solution. The solution was then sonicated and stirred thoroughly for 2 h. 7.5 mg of thiourea and 6.9 mg of gum arabic were added to the above mixed solution containing Ph-NH2-Br-COFs. The mixture was then ultrasonically dispersed and stirred for 1 h to form a homogeneous suspension. The stirred solution was transferred to a high-pressure reactor and reacted at 120 °C for 12 h. After cooling to room temperature, the mixture was filtered and washed several times with alternating ethanol and water. The filtered solid was then dried in a vacuum oven at 70 °C for 24 h to obtain the COFs-confined highly dispersed ZnS photocatalytic material Ph-NH2-Br-COFs@ZnS-20%. Infrared characterization showed that the aldehyde group (1690 cm⁻¹) in the Ph-NH2-Br-COFs monomer... -1 ) and amino (3208-3319cm) -1The disappearance of the characteristic peaks indicates that all aldehyde and amino groups in the Ph-NH2-Br-COFs monomer have been consumed, and Ph-NH2-Br-COFs have been successfully synthesized. When ZnS is supported on the surface of Ph-NH2-Br-COFs, the photocatalytic material simultaneously contains all the characteristic peaks of ZnS and Ph-NH2-Br-COFs, indicating that the reaction is successful. The prepared Ph-NH2-Br-COFs@ZnS-20% has a specific surface area of ​​up to 1050 m². 2 / g, pore volume is 0.92cm³ 3 ·g -1 It has a visible light absorption range of 610 nm and a band gap of 2.1 eV.

[0067] The photocatalytic performance was tested according to the method in Example 10: the CO yield in the photocatalytic CO2 reduction of the Ph-NH2-Br-COFs@ZnS-20% photocatalytic material prepared in Example 7 was 10.80 μmol·g. -1 ·h -1 The Ph-NH2-Br-COFs@ZnS-20% photocatalyst material prepared in Example 7 achieved a CO yield of 10.53 μmol·g after 5 cycles. -1 ·h -1 In practical applications, this photocatalytic material can be reused multiple times.

[0068] Example 8

[0069] Preparation of NH2-Br-COFs-1.5@ZnS-20% photocatalytic material:

[0070] 0.15 mmol of 2,5-dibromo-terephthalaldehyde and 0.15 mmol of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (0.15 mmol) were completely dissolved in a glass vial containing 3.0 mL of dioxane. The solution was sonicated for 60 min to form a clear, transparent solution. 0.3 mL of 3.0 mol / L acetic acid was then added, and the solution was sonicated for 2 min. The vial was sealed after three cycles of freezing-vacuum-thawing in a liquid nitrogen bath. It was then placed at 120 °C for 72 h. After cooling to room temperature, the solution was washed several times with tetrahydrofuran, acetone, and methanol. It was then purified using a Soxhlet extractor with tetrahydrofuran and methanol for 24 h. After vacuum drying at 60 °C for 24 h, the solution was collected to obtain NH₂-Br-COFs-1.5. 18.1 mg of zinc acetate dihydrate was fully dissolved in water. Then, 40 mg of NH₂-Br-COFs-1.5, fully swollen with ethanol, was added to the above solution, and the mixture was ultrasonically dispersed and stirred thoroughly for 2 hours. 7.5 mg of thiourea and 6.9 mg of gum arabic were added to the above mixed solution containing NH₂-Br-COFs-1.5, and the mixture was ultrasonically dispersed and stirred for another 1 hour to form a homogeneous suspension. The stirred mixture was transferred to a high-pressure reactor and reacted at 120 °C for 12 hours. After cooling to room temperature, the mixture was filtered and washed several times alternately with ethanol and water. The filtered solid was dried in a vacuum oven at 70 °C for 24 hours to obtain NH₂-Br-COFs-1.5@ZnS-20% photocatalytic material. Infrared characterization was performed as follows. Figure 2 As shown, the aldehyde group (1690 cm⁻¹) in the NH₂-Br-COFs-1.5 monomer... -1 ) and amino (3208-3319cm) -1 The disappearance of the characteristic peaks indicates that all the aldehyde and amino groups in the NH2-Br-COFs-1.5 monomer have been consumed, and NH2-Br-COFs-1.5 has been successfully synthesized. When ZnS is supported on the surface of NH2-Br-COFs-1.5, the photocatalytic material simultaneously contains all the characteristic peaks of ZnS and NH2-Br-COFs-1.5, indicating that the reaction is successful. The prepared NH2-Br-COFs-1.5@ZnS-20% has a specific surface area of ​​up to 1343 m². 2 / g, pore volume is 0.98cm³ 3 ·g -1 It has a visible light absorption range of 520 nm and a band gap of 2.53 eV.

[0071] The photocatalytic performance was tested according to the method in Example 10: the CO yield in the photocatalytic CO2 reduction of the NH2-Br-COFs-1.5@ZnS-20% photocatalytic material prepared in Example 8 was 11.24 μmol·g. -1 ·h -1The NH2-Br-COFs-1.5@ZnS-20% photocatalyst material prepared in Example 8 achieved a CO yield of 10.95 μmol·g after 5 cycles. -1 ·h -1 In practical applications, this photocatalytic material can be reused multiple times.

[0072] Example 9

[0073] Preparation of NH2-Br-COFs-2@ZnS-20% photocatalytic material:

[0074] 0.15 mmol of 2,5-dibromo-terephthalaldehyde and 0.2 mmol of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine were completely dissolved in a glass vial containing 3.0 mL of dioxane. The solution was sonicated for 60 min to form a clear, transparent solution. 0.3 mL of 3.0 mol / L acetic acid was then added, and the solution was sonicated for 2 min. The vial was sealed after three cycles of freezing-vacuum-thawing in a liquid nitrogen bath. The solution was then allowed to stand at 120 °C for 72 h. After cooling to room temperature, the solution was washed several times with tetrahydrofuran, acetone, and methanol. It was then purified using a Soxhlet extractor with tetrahydrofuran and methanol for 24 h, dried under vacuum at 60 °C for 24 h, and collected to obtain NH₂-Br-COFs-2. 18.1 mg of zinc acetate dihydrate was completely dissolved in water. 40 mg of NH₂-Br-COFs-2, fully swollen with ethanol, was then added to the above solution. The mixture was sonicated and stirred thoroughly for 2 h. 7.5 mg of thiourea and 6.9 mg of gum arabic were added to the above mixed solution containing NH2-Br-COFs-2. The mixture was then ultrasonically dispersed and stirred for 1 hour to form a homogeneous suspension. The stirred solution was transferred to a high-pressure reactor and reacted at 120 °C for 12 hours. After cooling to room temperature, the mixture was filtered and washed several times alternately with ethanol and water. The filtered solid was then dried in a vacuum oven at 70 °C for 24 hours to obtain the NH2-Br-COFs-2@ZnS-20% photocatalytic material. Infrared characterization was performed as follows. Figure 2 As shown, the aldehyde group (1690 cm⁻¹) in the NH₂-Br-COFs-2 monomer... -1 ) and amino (3208-3319cm) -1 The disappearance of the characteristic peaks indicates that all the aldehyde and amino groups in the NH2-Br-COFs-2 monomer have been consumed, and NH2-Br-COFs-2 has been successfully synthesized. When ZnS is supported on the surface of NH2-Br-COFs-2, the photocatalytic material simultaneously contains all the characteristic peaks of both ZnS and NH2-Br-COFs-2, indicating that the reaction is successful. The prepared NH2-Br-COFs-2@ZnS-20% has a specific surface area of ​​up to 1343 m². 2 / g, pore volume is 0.98cm³ 3 ·g-1 It has a visible light absorption range of 520 nm and a band gap of 2.53 eV.

[0075] The photocatalytic performance was tested according to the method in Example 10: the CO yield in the photocatalytic CO2 reduction of the NH2-Br-COFs-2@ZnS-20% photocatalytic material prepared in Example 9 was 11.24 μmol·g. -1 ·h -1 The NH2-Br-COFs-2@ZnS-20% photocatalyst material prepared in Example 9 achieved a CO yield of 10.95 μmol·g after 5 cycles. -1 ·h -1 In practical applications, this photocatalytic material can be reused multiple times.

[0076] Example 10

[0077] The photocatalytic CO2 reduction performance of the NH2-COFs@ZnS photocatalytic materials prepared in Examples 1-9 was tested.

[0078] (1) Photoelectric properties:

[0079] The photoelectrochemical testing of the prepared NH2-COFs@ZnS photocatalytic material was performed using an electrochemical workstation (CHI660E). A standard three-electrode system was employed, with Ag / AgCl as the reference electrode, a Pt sheet as the counter electrode, and the sample coated on FTO glass as the working electrode. The working electrode was prepared as follows: 5 mg of sample was dispersed in 475 μL of ethanol, sonicated for 40 min to ensure uniform dispersion, then 25 μL of Nafion membrane solution was added, and sonication was continued for another 5 min. 100 μL of the resulting solution was then dropped onto the FTO glass and dried. An Xe light source was used for the testing. The electrochemical workstation was used to measure the photocurrent response, electrochemical impedance spectroscopy, and Mott-Schottky curves.

[0080] (2) Photocatalytic CO2 reduction performance:

[0081] The photocatalytic CO2 reduction performance was assessed in a 150 mL reactor under xenon lamp irradiation. The specific procedure was as follows: 10 mg of the prepared photocatalyst was completely dispersed in 1 mL of deionized water, then transferred to a small evaporating dish, and finally dried under vacuum to remove moisture, obtaining a catalyst film. 0.084 g of NaHCO3 was weighed and placed into the reactor along with the prepared catalyst film. After purging, Ar gas was injected into the reactor for 20 min, followed by the slow introduction of 0.3 mL of 2 M H2SO4 to allow it to react fully with the NaHCO3 to generate CO2. Finally, a 300 W xenon lamp was used as the light source at the top 20 cm of the reactor, and the reaction system temperature was controlled at 5 °C using cooling water. Gas chromatography (GC) was used to analyze the gaseous products every 1 h.

[0082] (3) Reusability:

[0083] The above steps were repeated five times using the same sample. The photocatalytic CO2 reduction performance was measured, and the product yield was calculated.

Claims

1. A method for preparing an NH2-COFs@ZnS photocatalytic material, characterized in that: NH2-COFs materials are synthesized by reacting polyamino aromatic ligands and polyaldehyde aromatic ligands with Schiff base reaction. The NH2-COFs materials are then reacted with zinc salt and sulfur source by hydrothermal reaction to obtain the final product. The polyamino aromatic ligand is at least one of 2,4,6-tris(aminophenyl)-1,3,5-triazine and 1,3,5-tris(aminophenyl)benzene; The polyaldehyde aromatic ligand is at least one of 2,5-dibromo-terephthalaldehyde, 2,5-dimethoxy-terephthalaldehyde, 2,5-dihydroxy-terephthalaldehyde, and terephthalaldehyde. The molar ratio of the polyamino aromatic ligand to the polyaldehyde aromatic ligand is 1.2~2:1; The ratio of the NH2-COFs material to the zinc salt and sulfur source is measured according to a mass ratio of NH2-COFs material to generated ZnS of 1~4:

10.

2. The method for preparing an NH2-COFs@ZnS photocatalytic material according to claim 1, characterized in that: The Schiff base reaction conditions are: at a temperature of 20~120℃, the reaction time is 72 h~96 h.

3. A method for preparing an NH2-COFs@ZnS photocatalytic material according to claim 1 or 2, characterized in that: The hydrothermal reaction conditions are: at a temperature of 100~120℃, the reaction is carried out for 12 h~24 h.

4. An NH2-COFs@ZnS photocatalytic material, characterized in that: It is obtained by the preparation method described in any one of claims 1 to 3.

5. The NH2-COFs@ZnS photocatalytic material according to claim 4, characterized in that: The specific surface area of ​​the NH2-COFs@ZnS photocatalytic material is 700~1600 m². 2 / g, pore volume 0.5~1.0 cm³ 3 / g, with an average pore size of 1.0~4.0nm, an ultraviolet-visible absorption range of >500 nm, and a band gap of <2.6 eV.

6. The application of the NH2-COFs@ZnS photocatalytic material according to claim 4 or 5, characterized in that: It is used for photocatalytic reduction of CO2.

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