A type of reversible redox-catalytic covalent organic framework material, preparation method and application

Abstract

The present application discloses a type of reversible redox-catalytic covalent organic framework material, preparation method and application, by coupling the active sites of two functional units, namely D-A, that is, unit D has a reversible redox site, and unit A has a photo / photoelectrocatalytic active site. The material is stored in an energy storage manner using the characteristics of the redox groups of the material molecules under a photoelectric field, and the photoelectrochemical energy conversion is achieved using the characteristics of the reversible redox groups of the material molecules under a photoelectric field, thereby achieving a continuous cycle of photoelectrochemical energy storage and conversion. The present application provides a type of photoelectrochemical device based on a covalent organic framework with reversible redox sites and photo / photoelectrocatalytic activity. It has a high photoelectric conversion efficiency, avoids the use of additional sacrificial agents and photosensitizers, thereby improving the problems of low electron-hole separation efficiency and energy loss and expanding the application types of such covalent organic framework materials.

Description

Technical Field

[0001] The present application relates to a type of reversible redox-catalytic covalent organic framework material, preparation method and application, and belongs to the field of photo / electrocatalysis technology. Background Art

[0002] The method of converting solar energy into chemical energy to obtain clean, renewable energy is widely considered to be the most effective way to solve the energy crisis. Currently, a large number of studies are devoted to the purpose of artificial photosynthesis by analyzing and imitating natural photosynthesis. Among them, artificial photoelectrochemical systems are efficient, economical and portable. Through photo / photoelectrocatalytic water decomposition or carbon dioxide reduction, direct conversion of solar energy to chemical energy can be achieved, and ultimately continuous storage and conversion of photo / photoelectrochemical energy can be achieved. In the process of photo / photoelectrocatalytic water decomposition or carbon dioxide reduction.

[0003] Inspired by natural photosynthesis, a large number of studies have been devoted to the development of artificial photoelectrochemical systems to make them more efficient, compact and economical in the use of sunlight. Through photo / photoelectrocatalytic water splitting or CO2 reduction, the conversion process of solar energy to chemical energy can be directly carried out in the photo / photoelectrochemical system, thereby realizing the continuous storage and conversion of photo / photoelectrochemical energy. Among them, the photo / photoelectrocatalytic water splitting to generate O2 is the key half-reaction due to its complex four-electron oxidation process, and it is urgent to improve the photoelectric conversion efficiency of this reaction.

[0004] Covalent organic frameworks (COFs) are a class of ordered porous polymers. Their structural diversity (including topology, pores and skeletons) and functional precision have led to various applications in gas / molecule separation and capture, catalysis, chemical sensors and photocatalysis. Given the fast ion transport channels and well-defined photo / photoelectrocatalytic active sites, COFs have been used in photo / photoelectrochemical energy storage and conversion systems, including photocatalysis and photoelectrocatalysis. However, in photo / photoelectrochemical systems, in order to achieve continuous cycles of energy storage and conversion, it is often necessary to add additional sacrificial reagents or introduce other redox pairs into the molecules, which causes energy loss problems in the system. Therefore, making full use of the reversible redox sites in covalent organic framework molecules and combining them with catalytic functions has become a huge challenge in the field of photo / photoelectrocatalysis. Summary of the invention

[0005] This application designs a covalent organic framework photoelectrode with reversible redox sites and catalytic activity for use in a photoelectrochemical device. The device can achieve continuous photo / photoelectrochemical energy storage and conversion, thereby improving the increasingly serious energy shortage problem.

[0006] According to a first aspect of the present application, a class of reversible redox-catalytic covalent organic framework materials is provided, wherein the reversible redox-catalytic covalent organic framework material is formed by coupling an electron donor unit and an electron acceptor unit;

[0007] The electron donor unit is derived from a porphyrin-containing compound;

[0008] The electron acceptor unit is derived from diamino / dicarbonyl compounds.

[0009] Optionally, the molar ratio of the electron donor unit to the electron acceptor unit is 1:2 to 2:1.

[0010] Optionally, the porphyrin-containing compound is selected from one of the compounds represented by formula I-1 and the compounds represented by formula I-2;

[0011]

[0012] R1 and R2 are independently selected from one of an amino group and an aldehyde group;

[0013] M is selected from one of iron, cobalt, nickel and ruthenium.

[0014] Optionally, the diamino / dicarbonyl-containing compound is selected from one of the structures represented by aa, ab, ac, ad, ae, af, ag, ah, ai, aj, ak, al, am, an, ao, ba, bb, bc, bd, be, bf, bg, bh, bi, bj, bk, bl, bm, bn, bo, and bk;

[0015]

[0016]

[0017] M in the structures represented by aa, ag, ah, am, an, ao, ba, bg, bm, bn, bo, and bk is independently selected from one of iron, cobalt, nickel, and ruthenium.

[0018] Optionally, the reversible redox-catalytic covalent organic framework material has a crystallinity of 2 to 10 degrees.

[0019] Optionally, when R1 or R2 is selected from an amino group, the diamino / dicarbonyl-containing compound is selected from one of the structures represented by aa, ab, ac, ad, ae, af, ag, ah, ai, aj, ak, al, am, an, and ao;

[0020] When R1 or R2 is selected from an aldehyde group, the diamino / dicarbonyl-containing compound is selected from one of the structures shown in ba, bb, bc, bd, be, bf, bg, bh, bi, bj, bk, bl, bm, bn, bo, and bk.

[0021] According to the second aspect of the present application, a method for preparing the above-mentioned reversible redox-catalytic covalent organic framework material is provided, the preparation method comprising:

[0022] The reversible redox-catalytic covalent organic framework material is obtained by reacting a mixture of a porphyrin compound, a diamino / dicarbonyl compound and a solvent.

[0023] Optionally, the molar ratio of the porphyrin-containing compound to the diamino / dicarbonyl-containing compound is 1:2 to 2:1.

[0024] Optionally, the molar ratio of the porphyrin-containing compound to the diamino / dicarbonyl-containing compound is selected from any value of 1:2, 1.5:1, 1:1, 1:1.5, 2:1, or a range between any two of the above points.

[0025] Optionally, the solvent is selected from at least one of o-dichlorobenzene, ethanol, methanol, acetic acid, n-butanol, N,N-dimethylformamide, methylpyrrolidone and tetrahydrofuran.

[0026] Optionally, the molar ratio of the porphyrin-containing compound to the solvent is 0.01 to 1 mmol / mL.

[0027] Optionally, the reaction temperature is 120-220° C., and the reaction time is 24-240 hours.

[0028] Optionally, the reaction temperature is selected from any value of 120°C, 140°C, 160°C, 180°C, 200°C, 220°C or a range between any two of the above points.

[0029] Optionally, the reaction time is selected from any value among 24h, 48h, 60h, 72h, 120h, 140h, 160h, 180h, 240h or a range value between any two of the above points.

[0030] According to a third aspect of the present application, a photoanode is provided, the photoanode comprising a covalent organic framework material and an electrode substrate;

[0031] The covalent organic framework material is selected from the reversible redox-catalytic covalent organic framework material described above and the reversible redox-catalytic covalent organic framework material prepared by the preparation method described above.

[0032] According to a fourth aspect of the present application, a covalent organic framework photoelectrochemical device is provided, wherein the covalent organic framework photoelectrochemical device comprises an anode, a cathode, a dispersion solvent, and a reference electrode.

[0033] Optionally, the concentration of the dispersing solvent is 0.1 to 0.8 mol / L.

[0034] Optionally, the concentration of the dispersing solvent is selected from any value among 0.1 mol / L, 0.2 mol / L, 0.4 mol / L, 0.5 mol / L, 0.8 mol / L or a range between any two of the above points.

[0035] According to the fifth aspect of the present application, there is provided an application of a covalent organic framework photoelectrochemical device in photoelectrochemical energy storage and conversion, wherein the covalent organic framework photoelectrochemical device is selected from the covalent organic framework photoelectrochemical device described above.

[0036] Optionally, the light source of the covalent organic framework photoelectrochemical device is selected from at least one of a xenon lamp, an LED lamp, and natural light.

[0037] Optionally, the illumination time of the covalent organic framework photoelectrochemical device is 1 min to 300 min.

[0038] Optionally, the illumination time of the covalent organic framework photoelectrochemical device is selected from any value of 1 min, 30 min, 100 min, 150 min, 200 min, 250 min, 300 min, or a range between any two of the above points.

[0039] Optionally, the operating voltage of the covalent organic framework photoelectrochemical device is 0 to 2.5V.

[0040] Optionally, the operating voltage of the covalent organic framework photoelectrochemical device is selected from any value among 0V, 0.5V, 1V, 1.5V, 2.0V, 2.5V, or a range between any two of the above points.

[0041] In the present application, the covalent organic framework photoelectrochemical device is composed of a covalent organic framework photoanode having reversible redox sites-catalytic activity, a photocathode and a dispersed solvent.

[0042] The covalent organic framework photoanode with reversible redox site-catalytic activity is composed of a covalent organic framework and an electrode substrate.

[0043] Optionally, the electrode substrate includes but is not limited to at least one of fluorine-doped tin dioxide conductive glass (FTO), indium tin oxide conductive glass (ITO), silicon-based photoelectrode, carbon paper, carbon cloth, glassy carbon electrode, stainless steel mesh, etc. Among them, FTO is preferred.

[0044] Optionally, the monomer A monomer includes 5,10,15,20-tetrakis(4-aminobenzene)-21H,23H-porphyrin, 5,10,15,20-tetrakis(4-aminobenzene)-21H,23H-metalloporphyrin (metal M includes but is not limited to metals such as iron, cobalt, nickel and ruthenium), 5,10,15,20-tetrakis(4-formylbenzene)-21H,23H-porphyrin and 5,10,15,20-tetrakis(4-formylbenzene)-21H,23H-metalloporphyrin (metal M includes but is not limited to metals such as iron, cobalt, nickel and ruthenium).

[0045] Optionally, the monomer B monomer includes but is not limited to 5,10,15,20-tetrakis(4-aminobenzene)-21H,23H-porphyrin, 5,10,15,20-tetrakis(4-aminobenzene)-21H,23H-metalloporphyrin (metal M includes but is not limited to metals such as iron, cobalt, nickel and ruthenium), 5,10,15,20-tetrakis(4-formylbenzene)-21H,23H-porphyrin, 5,10,15,20-tetrakis(4-formylbenzene)-21H,23H-metalloporphyrin (metal M includes but is not limited to metals such as iron, cobalt, nickel and ruthenium), 5,5'-diamino-2,2'-bipyridine, 5,5'-dialdehyde-2,2'-bipyridine, terpyridine metal complex diformaldehyde ligand (metal M includes but is not limited to limited to metals such as iron, cobalt, nickel and ruthenium), terpyridine metal complex diamine ligand (metal M includes but is not limited to metals such as iron, cobalt, nickel and ruthenium), 3,10-diamino-1,1'-ethylene-2,2'-bipyridine, 3,10-dialdehyde-1,1'-ethylene-2,2'-bipyridine, p-phenylenediamine, terephthalaldehyde, 2,4,5,6-tetrafluoro-1,3-phenylenediamine, 2,3,5,6-tetrafluoro-p-dibenzaldehyde, 4,4'-[(2,2'-bipyridine)-5,5'-diyl]dibenzaldehyde, 4,4'-[(2,2'-bipyridine)-5,5'-diyl]diphenylamine, bipyridine 4,4'-[(2,2'-bipyridine)-5,5'-diyl]dibenzaldehyde metal complex ligand (Metal M includes but is not limited to metals such as iron, cobalt, nickel and ruthenium), bipyridine 4,4'-[(2,2'-bipyridine)-5,5'-diyl]benzaldehyde metal complex ligand (Metal M includes but is not limited to metals such as iron, cobalt, nickel and ruthenium), 1,10-phenanthroline-3,8-dicarboxaldehyde, 1,10-phenanthroline-3,8-diamine, 1,10-phenanthroline 1,10-phenanthroline-3,8-dicarboxaldehyde metal complex ligand (Metal M includes but is not limited to metals such as iron, cobalt, nickel and ruthenium), 1,10-phenanthroline 1,10-phenanthroline-3,8-diamine metal complex ligand (Metal M includes but is not limited to metals such as iron, cobalt, nickel and ruthenium), 10-phenanthroline-2,9-dicarboxaldehyde, 1,10-phenanthroline- 2,9-diamine, 1,10-phenanthroline 1,10-phenanthroline-2,9-dicarboxaldehyde metal complex ligand (metal M includes but is not limited to metals such as iron, cobalt, nickel and ruthenium), 1,10-phenanthroline 1,10-phenanthroline-2,9-diamine metal complex ligand (metal M includes but is not limited to metals such as iron, cobalt, nickel and ruthenium), 10-phenanthroline-4,7-dicarboxaldehyde, 1,10-phenanthroline-4,7-diamine, 1,10-phenanthroline 1,10-phenanthroline-4,7-dicarboxaldehyde metal complex ligand (metal M includes but is not limited to metals such as iron, cobalt, nickel and ruthenium), 1,10-phenanthroline 1,10-phenanthroline-4,7-diamine metal complex ligand (metal M includes but is not limited to metals such as iron, cobalt, nickel and ruthenium).

[0046] Optionally, the usage ratio of the monomer A to the monomer B is 1:2 to 2:1.

[0047] Optionally, the preparation method of the covalent organic framework material is as follows: a reaction precursor is dispersed in a reaction solvent, and the reaction is carried out at a certain temperature to prepare the covalent organic framework material.

[0048] Optionally, the covalent organic framework material needs to be filtered, washed and dried.

[0049] Optionally, the reaction precursor is selected from monomer A and monomer B.

[0050] Optionally, the reaction solvent includes an organic solvent and water.

[0051] Optionally, the reaction solvent includes an organic solvent and water.

[0052] Optionally, the organic solvent is selected from at least one of o-dichlorobenzene, ethanol, methanol, acetic acid, n-butanol, N,N-dimethylformamide, methyl pyrrolidone and tetrahydrofuran.

[0053] Optionally, in the method for preparing the covalent organic framework material, the reaction method is selected from at least one of a solvent thermal method, a hydrothermal method, a melting method, and a vacuum sealing method.

[0054] Optionally, the conditions of the solvothermal method include: a reaction temperature of 120 to 220°C, exemplified by 120°C, 140°C, 180°C, and 220°C; a reaction time of 24 to 240 hours, exemplified by 24 hours, 72 hours, and 160 hours. The crystallization of the covalent organic framework can be promoted within the above reaction temperature range; and the reaction can be made more complete within the above reaction time.

[0055] In the present application, in the covalent organic framework photoelectrode, the loading method of the covalent organic framework and the substrate includes but is not limited to drop coating, spin coating and in-situ synthesis, wherein the drop coating method is preferred.

[0056] In this application, the photoanode is composed of a catalytic material and a substrate.

[0057] In the present application, the photoanode substrate includes but is not limited to fluorine-doped tin dioxide conductive glass (FTO), indium tin oxide conductive glass (ITO), silicon-based photoelectrode, carbon paper, carbon cloth, etc. Among them, FTO is preferred.

[0058] In the present application, the photocathode catalytic material is selected from at least one of gold, platinum, and graphite rod; among them, platinum is preferred.

[0059] The present application also provides a design of a photoelectrocatalytic dispersion solvent, wherein the light / photoelectrocatalytic dispersion solvent system includes a solute and a solvent.

[0060] According to the embodiment of the present application, the solute in the dispersed aqueous solution includes an inorganic system and an organic system; the inorganic system is selected from at least one of potassium bicarbonate, sulfuric acid, sodium hydroxide, and sodium sulfate; the organic system is selected from acetonitrile and / or DMF; among which a sulfuric acid solution under an inorganic system is preferred.

[0061] The present application also provides the use of the above-mentioned photoelectrode and dispersing solvent, that is, for designing a photoelectrochemical device based on a covalent organic framework photoelectrode with reversible redox sites and catalytic activity.

[0062] According to the embodiment of the present application, the covalent organic framework photoelectrochemical device is capable of storing and converting photoelectrochemical energy.

[0063] The present application also provides a method for constructing the above-mentioned covalent organic framework photoelectrochemical device catalytic system, and the construction method includes the following steps: preparing a photoanode from the above-mentioned catalytic material, preparing a photoelectrode from metal platinum or the above-mentioned material, assembling the photoanode and the photocathode with an inorganic solvent into a photoelectrochemical device, and storing and converting energy under light / photoelectric conditions.

[0064] According to an embodiment of the present application, the photoelectrode material has the meaning as described above.

[0065] According to an embodiment of the present application, the organic photoelectrocatalytic system includes a photoelectrode and a solvent.

[0066] According to an embodiment of the present application, the illumination is provided by a light source, and the light source is selected from at least one of a 300W xenon lamp, an LED lamp, and natural light.

[0067] According to an embodiment of the present application, the voltage is provided by an electrochemical workstation.

[0068] The beneficial effects of this application include:

[0069] 1) The present application provides an application of a class of covalent organic frameworks, which couples two functional motifs, namely, the active sites of DA, namely, motif D has a reversible redox site, and motif A has a photo / photoelectrocatalytic active site. The material is stored in the photoelectric field by utilizing the characteristics of the redox groups of the material molecules, and the photoelectrochemical energy conversion is achieved by utilizing the characteristics of the reversible redox groups of the material molecules in the photoelectric field, thereby realizing a continuous cycle of photoelectrochemical energy storage and conversion.

[0070] 2) The photoelectrochemical device based on the covalent organic framework photoelectrode provided in this application has a simple preparation process, low cost, high photoelectric conversion efficiency, and is suitable for industrial promotion.

[0071] 3) The present application provides a type of photoelectrochemical device based on a covalent organic framework with reversible redox sites and photo / photoelectrocatalytic activity. It has a high photoelectric conversion efficiency and avoids the use of additional sacrificial agents and photosensitizers, thereby improving the problems of low electron-hole separation efficiency and energy loss and expanding the application of such covalent organic framework materials.

[0072] 4) The present application provides a type of device with photoelectric response and photoelectrochemical energy storage and conversion cycle. Under the light radiation of a 300W xenon lamp (simulating sunlight, AM1.5) and a bias voltage of 1.0V, the device can achieve a maximum solar-to-chemical energy conversion efficiency of 5% O2 and 860μmol h -1 of hydrogen or 540 μmol h -1 The CO generation rate and the construction of the conversion system improve the time influence problem in solar energy utilization and conversion. This application provides reference value for designing photoelectrocatalytic materials for recyclable photoelectrochemical energy storage and conversion devices, solves the problem of low solar-to-chemical energy conversion efficiency in traditional photoelectrocatalytic systems, and uses solar energy in a targeted manner through time decoupling. It has the advantages of wider applicability, high solar-to-chemical energy conversion efficiency, and green sustainable development, and provides new insights into the design and application of solar-to-chemical energy storage and conversion systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Figure 1 This is a schematic diagram of the structure of the covalent organic framework material prepared in Example 1 of the present application.

[0074] Figure 2 This is the X-ray powder diffraction pattern of the covalent organic framework material prepared in Example 1 of the present application.

[0075] Figure 3 This is a scanning electron microscope image of the covalent organic framework material prepared in Example 1 of the present application at 400nm.

[0076] Figure 4 This is a physical picture of the covalent organic framework material prepared in Example 1 of the present application.

[0077] Figure 5 This is the theoretically calculated charge transfer diagram of the covalent organic framework material prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0078] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0079] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0080] This application uses an X-ray powder diffractometer (Rigaku Miniflex 600), an electrochemical workstation (Shanghai Chenhua 660e), a gas chromatograph (GC9790), and a trace gas detector (Perfectlight6A) to test the crystallinity and photoelectric conversion performance of the covalent organic framework material.

[0081] As a specific implementation method, the present application is implemented through the following technical solutions:

[0082] In the present application, the covalent organic framework is formed by coupling two functional units, namely, electron donor-acceptor (DA) units, which can be divided into monomer A (donor) and monomer B (acceptor), as shown in Table 1 and Table 2.

[0083] Table 1

[0084]

[0085] Table 2

[0086]

[0087] Example 1

[0088] 0.05mmol 5,10,15,20-tetrakis(4-aminophenyl)-21H,23H-cobalt porphyrin (Co-TAP) and 0.1mmol 2,2-bipyridine-5,5-dicarbaldehyde (Bpy) were added to the reaction tube, and 2mL o-dichlorobenzene (DCB) and 2mL n-butanol (n-BuOH) were added. After ultrasonication for 10 minutes, 0.5mL 6M acetic acid solution (6M HOAc) was added, and the tube was frozen with liquid nitrogen. After freezing, the tube was degassed on a double-row tube for 10 minutes, nitrogen was replaced 3-5 times, and the tube was thawed under nitrogen protection. Then, the tube was frozen and degassed for 10 minutes, nitrogen was replaced 3-5 times, and nitrogen was replaced 3-5 times. After thawing, the tube was frozen and degassed for 10 minutes, nitrogen was replaced 3-5 times, and nitrogen was replaced 3-5 times. After thawing, the tube was frozen and degassed again for 10 minutes, nitrogen was replaced 3-5 times, and nitrogen was replaced 3-5 times. After thawing, the tube was frozen and degassed again, nitrogen was replaced 3-5 times, and nitrogen was replaced 3-5 times. After thawing, the tube was heated at 120°C for 3 days. After cooling, the product was filtered, washed with ethanol three times, and dried under vacuum at 60°C overnight to obtain a dark red solid, which was named COF-4.

[0089] from Figure 1 It can be seen that the synthetic route and conditions for preparing COF-4 shown in Example 1;

[0090] from Figure 2 It can be seen that the COF prepared in Example 1 has excellent crystallinity and is consistent with the conclusion of theoretical calculation simulation;

[0091] from Figure 3 It can be seen that COF-4 has a nanoscale small cubic microcrystalline morphology with excellent crystallinity and dispersibility;

[0092] from Figure 4 It can be seen that COF-4 has a red-black color and a loose morphology in the macroscopic view;

[0093] from Figure 5 It can be seen from the theoretical calculations that the direction of intramolecular charge transfer is from the cobalt porphyrin electron donor to the 4,4-bipyridine electron acceptor.

[0094] Example 2

[0095] 0.05mmol 5,10,15,20-tetrakis(4-aminophenyl)-21H,23H-cobalt porphyrin (Co-TAP), 0.1mmol 2,2-bipyridine-5,5-dicarboxaldehyde (Bpy), 0.2mmol nickel acetate tetrahydrate and 0.2mmol 2,2-bipyridine were added to the reaction tube, 2mL o-dichlorobenzene (DCB) and 2mL n-butanol (n-BuOH) were added, and after ultrasonication for 10 minutes, 0.5mL 6M acetic acid solution (6M HOAc) was added, and the mixture was frozen with liquid nitrogen. After freezing, the mixture was degassed on a double-row tube for 10 minutes, nitrogen was replaced 3-5 times, and the mixture was thawed under nitrogen protection, and then the mixture was degassed for 10 minutes again, nitrogen was replaced 3-5 times, and the mixture was thawed under nitrogen protection, and the mixture was degassed for 10 minutes again, nitrogen was replaced 3-5 times, and the mixture was thawed under nitrogen protection, and the mixture was degassed for 10 minutes again, nitrogen was replaced 3-5 times, and the mixture was sealed with a polytetrafluoroethylene stopper, thawed, and heated at 120°C for 3 days. After cooling, the product was filtered, washed with ethanol three times, and dried under vacuum at 60°C overnight to obtain a brown-red solid, which was named COF-2.

[0096] Application Example 1

[0097] The design of covalent organic framework photoelectrochemical devices includes the following steps:

[0098] (1) Preparation process of photoanode of covalent organic framework photoelectrochemical device: 10 mg of COF-4 covalent organic framework material prepared in Example 1 was weighed and dispersed in 1 mL of isopropanol solution, and 50 μL of binder Nafion solution was added. After the mixed solution was sheared for 30 min with a shearing machine, it was drop-coated on fluorine-doped tin dioxide conductive glass (FTO), and after natural drying, the photoanode of the covalent organic framework photoelectrochemical device was obtained for use.

[0099] (2) Preparation process of photocathode of covalent organic framework photoelectrochemical device: using commercial platinum mesh.

[0100] (3) Solvent preparation process of covalent organic framework photoelectrochemical device: Prepare 0.5M H2SO4 solution and take 50mL of the above solvent as the dispersing solvent in the photoelectrocatalytic system.

[0101] (4) Assembly of covalent organic framework photoelectrochemical device: 50 mL of solvent was added to a photoelectrocatalytic device with a capacity of 110 mL. The photocathode and photoanode of the photoelectrochemical device prepared above were clamped with electrode clamps respectively. The catalyst material drop-coated part on FTO was immersed in the solvent. The Ag / AgCl electrode was used as the reference electrode. The device system was sealed and exposed to Ar gas for 30 min before the experiment.

[0102] (5) Place the assembled covalent organic framework photoelectrochemical device in front of a 300W xenon lamp (full spectrum, incident light wavelength between 200-1000nm), with the photoanode as the working electrode, the platinum cathode as the counter electrode, and the Ag / AgCl electrode as the reference electrode. Apply a bias of ~1.0V to the device, and the bipyridine is oxidized to positive ions accompanied by the embedding of protons. At the same time, hydrogen is produced at the cathode, which takes time t1. Illuminate the photoanode in the device, and proton deintercalation is accompanied by the production of oxygen, which takes time t2. Connect the device to an electrochemical workstation and apply a bias of ~1.0V to the device, which takes time t3. In summary, the photoelectrochemical process is completed, the photoelectrochemical water splitting cycle is completed, and multiple cycles can be performed continuously.

[0103] The experimental results show that the covalent organic framework photoelectrochemical device prepared in Application Example 1 can achieve a photoelectric conversion efficiency of 5% O2 solar energy to chemical energy and a maximum of 860 μmol h-1 under the light radiation of a 300W xenon lamp and a bias voltage of 1.0V. -1 The hydrogen generation rate.

[0104] Application Example 2

[0105] The method and steps for designing the covalent organic framework photoelectrochemical device in Application Example 2 are basically the same as those in Application Example 1, except that:

[0106] In step (1), the covalent organic framework material COF-4 is replaced with the COF-2 type covalent organic framework material prepared in Example 2;

[0107] In step (3), the 0.5M H2SO4 solution is replaced with a 0.5M KHCO3 solution;

[0108] In step (4), the Ar gas is replaced with CO2 gas;

[0109] In step (5), the cathode is replaced with a gold sheet, and a carbon dioxide reduction reaction occurs at the cathode to generate a CO product.

[0110] The remaining steps are the same as those in Application Example 1, where the redox reaction takes place on the metal complex.

[0111] The experimental results show that the covalent organic framework photoelectrochemical device prepared in Application Example 2 can achieve a solar-to-chemical energy conversion efficiency of 4.5% O2 and a maximum of 540 μmol h-1 under the light radiation of a 300 W xenon lamp and a bias voltage of 1.3 V. -1 The rate of carbon monoxide production.

[0112] Application Example 3

[0113] The method and steps for designing a covalent organic framework photoelectrochemical device in Application Example 3 are basically the same as those in Application Example 2, except that:

[0114] In step (3), the dispersion solvent of the photoelectrochemical device is changed to 0.8M KHCO3;

[0115] In step (5), the photoelectrocatalytic oxygen generation reaction is carried out under an additional bias voltage of 0.3 V.

[0116] The remaining steps are the same as those in Application Example 2.

[0117] The experimental results show that the photoelectric response covalent organic framework photoelectrochemical device prepared in Application Example 2 can achieve a solar-to-chemical energy conversion efficiency of 2.8% O2 and a maximum of 625 μmol h-1 under the light radiation of a 300 W xenon lamp and an additional bias of -0.3 V. -1 The rate of carbon monoxide production.

[0118] Comparative application example 1

[0119] The design method steps for preparing the covalent organic framework photoelectrochemical device in this comparative application example are basically the same as those in Application Example 1, except that: when preparing the photoelectrode sheet slurry in step (1), no covalent organic framework material is added; the remaining steps are the same as those in Application Example 1.

[0120] The experimental results show that the photoelectric response covalent organic framework photoelectrochemical device prepared in Comparative Example 1 has a very low solar-to-chemical energy conversion efficiency, close to 0, under the light radiation of a 300W xenon lamp and a bias voltage of 1.0V. Comparative Application Example 1 shows that the introduction of a covalent organic framework material with reversible redox sites and photocatalytic activity is a necessary condition for achieving effective photoelectric conversion efficiency.

[0121] Comparative Application Example 2

[0122] The method steps for designing the application system for preparing the photoelectric responsive covalent organic framework photoelectrochemical device in this comparative application example are basically the same as those in Application Example 1, except that: in step (5), the assembled photoelectric responsive covalent organic framework photoelectrochemical device is not illuminated.

[0123] The experimental results show that the photoelectric conversion efficiency of the photoelectric response covalent organic framework photoelectrochemical device of comparative application example 2 is low and close to 0. Comparative application example 2 confirms that only when the light energy is continuously irradiated can the light / photoelectric energy-chemical energy conversion process be induced to realize the light / photoelectric catalytic phenomenon.

[0124] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A covalent organic framework photoelectrochemical device, characterized in that: The covalent organic framework photoelectrochemical device comprises an anode, a cathode, a dispersed aqueous solution, and a reference electrode; The solute in the dispersed aqueous solution is selected from at least one of potassium bicarbonate, sulfuric acid, sodium hydroxide, sodium sulfate, acetonitrile, and DMF; The anode comprises a covalent organic framework material and an electrode substrate; The covalent organic framework material is a reversible redox-catalytic covalent organic framework material; The reversible redox-catalytic covalent organic framework material is formed by coupling an electron donor unit and an electron acceptor unit; The electron donor unit is derived from a porphyrin-containing compound; The porphyrin-containing compound is selected from one of the compounds represented by formula I-1 and the compounds represented by formula I-2; R1 and R2 are independently selected from one of an amino group and an aldehyde group; The electron acceptor unit is derived from diamino / dicarbonyl compounds; The diamino / dicarbonyl-containing compound is selected from one of the structures represented by aa, ab, ba, and bb; M is selected from one of iron, cobalt, nickel and ruthenium; The covalent organic framework photoelectrochemical device comprises a light source.

2. The covalent organic framework photoelectrochemical device according to claim 1, characterized in that: The molar ratio of the electron donor unit to the electron acceptor unit is 1:2 to 2:

1.

3. The covalent organic framework photoelectrochemical device according to claim 1, characterized in that: The reversible redox-catalytic covalent organic framework material has a crystallinity of 2 to 10 degrees.

4. The covalent organic framework photoelectrochemical device according to claim 1, characterized in that: The preparation method of the reversible redox-catalytic covalent organic framework material comprises: The reversible redox-catalytic covalent organic framework material is obtained by reacting a mixture of a porphyrin compound, a diamino / dicarbonyl compound and a solvent.

5. The covalent organic framework photoelectrochemical device according to claim 4, characterized in that: The molar ratio of the porphyrin-containing compound to the diamino / dicarbonyl-containing compound is 1:2 to 2:

1.

6. The covalent organic framework photoelectrochemical device according to claim 4, characterized in that: The solvent is selected from at least one of o-dichlorobenzene, ethanol, methanol, acetic acid, n-butanol, N,N-dimethylformamide, methyl pyrrolidone and tetrahydrofuran.

7. The covalent organic framework photoelectrochemical device according to claim 4, characterized in that: The molar ratio of the porphyrin-containing compound to the solvent is 0.01 to 1 mmol / mL.

8. The covalent organic framework photoelectrochemical device according to claim 4, characterized in that: The reaction temperature is 120-220° C., and the reaction time is 24-240 hours.

9. The covalent organic framework photoelectrochemical device according to claim 1, characterized in that: The concentration of the dispersed aqueous solution is 0.1-0.8 mol / L.

10. Application of a covalent organic framework photoelectrochemical device in photoelectrochemical energy storage and conversion, characterized in that: The covalent organic framework photoelectrochemical device is selected from the covalent organic framework photoelectrochemical device according to any one of claims 1 to 9.

11. The use according to claim 10, characterized in that: The light source of the covalent organic framework photoelectrochemical device is selected from at least one of a xenon lamp, an LED lamp, and natural light.

12. The use according to claim 10, characterized in that: The illumination time of the covalent organic framework photoelectrochemical device is 1 min to 300 min.

13. The use according to claim 10, characterized in that: The operating voltage of the covalent organic framework photoelectrochemical device is 0-2.5V.

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