Preparation methods and applications of photocatalysts coupling CO2 photoreduction and H2O oxidation

Abstract

The application provides a preparation method and application of a photocatalyst for coupling of CO2 photoreduction and H2O oxidation, and comprises the following steps: S1, preparing MOF-919-Cu3 by a hydrothermal method; S2, preparing MOF-919-Cu2M (M is one of Co, Zn and Cu) from the MOF-919-Cu3 prepared in step S1, and performing activation treatment; S3, mixing and stirring the activated MOF-919-Cu2M with a solvent of PbBr2, cleaning by using the solvent, obtaining PbBr2@MOF-919-Cu2M dispersed in the solvent, obtaining a PbBr2@MOF-919-Cu2M solution, adding a CsBr solution into the PbBr2@MOF-919-Cu2M solution, stirring, filtering and washing CsPbBr3@MOF-919-Cu2M, and obtaining CsPbBr3@MOF-919-Cu2M. The application has the beneficial effects that the process is simple, convenient to operate and has a high yield, can obtain a photocatalyst with high activity and selectivity, and is expected to become a universal and convenient method for preparing a double-coupling photocatalyst.

Description

Technical Field

[0001] This invention belongs to the field of catalysis technology, and in particular relates to the preparation method and application of photocatalysts that couple CO2 photoreduction and H2O oxidation. Background Technology

[0002] Inspired by natural photosynthesis, utilizing sunlight to convert CO2 and H2O into value-added fuels and O2 is considered a potential solution to the energy and environmental problems caused by the excessive combustion of fossil fuels. However, achieving efficient overall reactions remains challenging due to the high chemical inertness of CO2 and H2O molecules, and the multi-electron and multi-proton transfer processes involved in CO2 reduction and H2O oxidation. Therefore, the development of efficient photocatalysts is needed to realize artificial photosynthesis. In the past few decades, researchers have constructed heterojunction photocatalysts by integrating different semiconductors. Due to the synergistic effect between different components, charge separation efficiency has been improved, thereby enhancing catalytic activity. In particular, metal halide perovskites (MHPs) have been widely used in the preparation of composite photocatalysts due to their wide light absorption range, long carrier lifetime, and large extinction coefficient. However, due to the lack of effective catalytic sites, the reported MHP-based composite photocatalysts have insufficient catalytic activity for CO2 photoreduction.

[0003] In recent years, bimetallic catalysts (DMCs) have attracted increasing attention in the field of carbon dioxide emission reduction due to their unique properties. Firstly, the tightly coupled bimetallic sites in DMCs can produce a synergistic catalytic effect, significantly reducing the reaction free energy of the rate-determining step compared to a single site, thereby improving catalytic activity. Secondly, the atomically dispersed bimetallic sites in DMCs allow for in-depth understanding of the structure-activity relationship at the atomic scale. Although many DMCs have been reported to possess the ability to synergistically catalyze CO2 reduction, how to modulate bimetallic sites to promote CO2 photoreduction remains unclear. It is well known that the catalytic activity of CO2 photoreduction largely depends on the binding strength between the catalytic site and the intermediate. Therefore, adjusting the binding strength between the biatomic sites and the reaction intermediate can modulate the photocatalytic performance of CO2 reduction. Against this backdrop, it is essential to construct suitable composite catalysts that combine MHPs with synergistic bimetallic catalytic sites to achieve efficient CO2 photoreduction and to gain a deeper understanding of the influence of bimetallic sites on CO2 reduction activity. Summary of the Invention

[0004] In view of this, the present invention aims to propose a method for preparing and applying a photocatalyst coupling CO2 photoreduction and H2O oxidation. This method involves encapsulating CsPbBr3 quantum dots (QDs) within the pores of a mesoporous trinuclear Cu2M cluster-based metal-organic framework (MOF-919-Cu2M, M = Cu, Co, Zn), thus preparing a series of CsPbBr3@MOF-919-Cu2M heterojunctions for CO2 photoreduction using H2O as an electron donor. The results show that CsPbBr3@MOF-919-Cu2Co exhibits the highest photocatalytic activity, with an HCOOH formation rate of 332.2 μmol g. -1 h -1 The yields are 64 times and 55 times that of CsPbBr3 and MOF-919-Cu3, respectively, and the selectivity can reach 100%. This process is simple, easy to operate, and has a high yield, and can obtain photocatalysts with high activity and selectivity. It is a general and convenient method for preparing dual synergistic photocatalysts.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] The preparation method of the photocatalyst coupled with CO2 photoreduction and H2O oxidation includes the following steps:

[0007] S1: MOF-919-Cu3 was prepared by a hydrothermal method;

[0008] S2: Place the MOF-919-Cu3 prepared in step S1 in a solvent containing Co(NO3)2·6H2O or Zn(NO3)2·6H2O, and heat it to obtain MOF-919-Cu2M (M is one of Co, Zn, or Cu). After soaking MOF-919-Cu2M in the solvent, dry it to obtain activated MOF-919-Cu2M.

[0009] S3: Mix and stir the activated MOF-919-Cu2M with PbBr2 in solvent to obtain PbBr2@MOF-919-Cu2M. Wash the PbBr2@MOF-919-Cu2M with solvent and disperse the PbBr2@MOF-919-Cu2M in solvent to obtain PbBr2@MOF-919-Cu2M solution. Add CsBr solution to the PbBr2@MOF-919-Cu2M solution and stir. Filter and wash CsPbBr3@MOF-919-Cu2M to obtain CsPbBr3@MOF-919-Cu2M.

[0010] Further, the preparation of MOF-919-Cu3 in step S1 includes the following steps:

[0011] ScCl3·6H2O, Cu(NO3)2·3H2O, 1H-pyrazole-4-carboxylic acid and solvent were mixed, heated and cooled to room temperature, filtered and soaked, and then vacuum dried to obtain MOF-919-Cu3.

[0012] Further, in step S1, ScCl3·6H2O, Cu(NO3)2·3H2O, 1H-pyrazole-4-carboxylic acid are mixed with a solvent, the solvent being N,N-dimethylformamide;

[0013] Preferably, the temperature after heating and cooling to room temperature is 90-110°C, and the heating time is 14-16 hours;

[0014] Preferably, the soaking after filtration includes soaking in DMF for 2-4 days, followed by soaking in ethanol for 2-4 days;

[0015] Preferably, vacuum drying is performed at 50-70°C for 11-13 hours.

[0016] Furthermore, in step S2, the molar ratio of ScCl3·6H2O, Cu(NO3)2·3H2O, and 1H-pyrazole-4-carboxylic acid is 1:2~2.6:1.3~1.7;

[0017] In step S2, the solvent for Co(NO3)2·6H2O or Zn(NO3)2·6H2O is DMF.

[0018] Furthermore, in step S2, the concentration of Co(NO3)2·6H2O is 0.5 mol / L, and the concentration of Zn(NO3)2·6H2O is 0.5 mol / L;

[0019] Preferably, the heating temperature for obtaining MOF-919-Cu2M after heating in step S2 is 80-100℃;

[0020] Preferably, MOF-919-Cu2M is soaked in DMF and ethanol for 2-4 days, vacuum filtered and dried at 50-70℃ for 11-13 hours, and then vacuum dried at 140-160℃ for 11-13 hours to obtain activated MOF-919-Cu2M.

[0021] Furthermore, in step S3, the mass ratio of MOF-919-Cu2M, PbBr2 and CsBr is 1:0.9-0.1:1-1.1.

[0022] In step S3, the solvent for PbBr2 is DMF solution; the mixing and stirring time between MOF-919-Cu2M and PbBr2 in the solvent is 1-3 hours.

[0023] Further, in step S3, PbBr2@MOF-919-Cu2M is filtered and washed in a mixed solution of DMF and ethanol; preferably, the volume ratio of DMF to ethanol is 1:05 to 1.5.

[0024] Preferably, PbBr2@MOF-919-Cu2M is dissolved in toluene, and the solvent of CsBr solution is methanol; PbBr2@MOF-919-Cu2M toluene solution is added to CsBr solution, stirred at room temperature for 4-6 minutes, and CsPbBr3@MOF-919-Cu2M is collected after filtration and washing with n-hexane several times.

[0025] The catalyst prepared by the method of coupling CO2 photoreduction and H2O oxidation has CsPbBr3 quantum dots uniformly distributed in mesoporous MOF-919-Cu2M, with CsPbBr3 size ranging from 2.0 to 5.0 nm.

[0026] The preparation method of photocatalysts coupling CO2 photoreduction and H2O oxidation is applied to photocatalytic CO2 reduction reaction.

[0027] The solution for the photoreaction is CH3CN and H2O; preferably, the light intensity used for the photoreaction is 250–350 mW·cm. -2 A xenon lamp (λ≥420nm) is used as the illumination source.

[0028] The photocatalytic CO2 reduction reaction was carried out in a 16 mL quartz tube, using CsPbBr3@MOF-919-Cu2M (1 mg) as the catalyst, without the addition of photosensitizers or electron sacrificial agents. The reaction system consisted of CH3CN (5 mL) and H2O (20 μL). A light intensity of 300 mW·cm⁻¹ was used. -2 A xenon lamp (λ≥420nm) was used as the irradiation source. Before the catalytic reaction began, CO2 was introduced into the reactor to remove O2 and other gases. After the reaction, the gases produced in the experiment were analyzed by GC to detect the gaseous products, and the solutions were analyzed by ion chromatography to detect the liquid products.

[0029] To achieve this goal, MOFs, as a class of crystalline porous materials, are ideal candidate materials due to the following unique advantages: 1) High surface area, well-exposed active sites, and semiconductor behavior are all conducive to photocatalytic CO2 reduction; 2) The permanent pores of MOFs can encapsulate MHPs to form composite photocatalysts; 3) The tunability of nodes and structures based on metal clusters provides opportunities to regulate different bimetallic sites; 4) Periodicity and well-defined structure greatly facilitate a deeper understanding of the bimetallic synergistic mechanism.

[0030] Based on the above considerations, we embedded CsPbBr3 quantum dots within the pores of a Cu2M cluster-based MOF (M = Cu, Zn, Co) to prepare three CsPbBr3@MOF-919-Cu2M composite catalysts for the visible light-induced reduction of CO2 to HCOOH and the oxidation of H2O to O2. Experimental results showed that direct contact between CsPbBr3 quantum dots and MOF-919-Cu2M significantly improved the photogenerated electron transfer efficiency of CsPbBr3@MOF-919-Cu2M. More surprisingly, within the Cu2M cluster, one of the Cu and M sites exhibited a bimetallic synergistic catalytic effect, significantly reducing the HCOOH* reaction free energy. The binding strength of the bimetallic site to the HCOO* intermediate was [value missing - likely a value missing in original text]. + / Co 2+ >Cu + / Zn 2+ >Cu + / Cu 2+ Therefore, MOF-919-Cu2Co exhibits the best synergistic effect.

[0031] Compared with existing technologies, the preparation method and application of the photocatalyst for coupling CO2 photoreduction and H2O oxidation described in this invention have the following advantages:

[0032] The CsPbBr3@MOF-919-Cu2Co of this application exhibits the highest photocatalytic activity, with an HCOOH formation rate of 332.2 μmol g. -1 h -1 The photocatalysts exhibited 64 times and 55 times the photocatalytic activity of CsPbBr3 and MOF-919-Cu3, respectively, with a selectivity of 100%. Compared with existing technologies, the catalyst preparation method provided by this invention is simple to operate, has excellent photocatalytic performance, and facilitates catalyst recyclability, thus possessing commercial application value. Attached Figure Description

[0033] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0034] Figure 1 This is a schematic diagram illustrating the preparation principle of a CsPbBr3@MOF-919-Cu2M heterojunction according to the present invention.

[0035] Figure 2 The powder X-ray diffraction patterns of the catalysts prepared in Examples 1, 2, 3, 1, 2, and 4 of this invention are shown.

[0036] Figure 3The N2 adsorption-desorption isotherms of a CsPbBr3@MOF-919-Cu2M catalyst of the present invention are shown in Figure 1 (a is the N2 adsorption-desorption isotherm of Example 1 and Comparative Example 1, b is the N2 adsorption-desorption isotherm of Example 2 and Comparative Example 2, and the N2 adsorption-desorption isotherm of Example 3 and Comparative Example 3).

[0037] Figure 4 The X-ray photoelectron spectra of a CsPbBr3@MOF-919-Cu2M catalyst before and after irradiation are shown in the figure below (a is the X-ray photoelectron spectra of Cs 3d before and after irradiation of Example 1 and CsPbBr3, and b is the X-ray photoelectron spectra of Cu 2p before and after irradiation of Example 1 and 919-Cu2Co).

[0038] Figure 5 The images shown are ultra-high resolution transmission electron microscope (UHEM) images of a CsPbBr3@MOF-919-Cu2M catalyst of the present invention (a is UHEM image of Example 3, b is UHEM image of Example 1, and c is UHEM image of Example 2).

[0039] Figure 6 The graphs show the changes in CO2 photoreduction products of the catalysts in Examples 1, 2, and 3 of this invention over time. Detailed Implementation

[0040] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0041] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0042] Example 1

[0043] MOF-919-Cu3 was prepared by a hydrothermal method: ScCl3·6H2O (76.2 mg), Cu(NO3)2·3H2O (135.6 mg), 1H-pyrazole-4-carboxylic acid (H2PyC) (34.8 mg), and N,N-dimethylformamide (10 mL) were added to a 20 mL heat-resistant glass vial and heated at 100 °C for 15 hours. After cooling to room temperature, the green product was collected by filtration, soaked in DMF for 3 days, and then soaked in ethanol for 3 days. It was then vacuum dried at 60 °C for 12 hours. Then, MOF-919-Cu3 (20 mg) was placed in a 5 mL solution of Co(NO3)2·6H2O (0.5 mol / L) in DMF and heated at 90 °C for 24 hours to obtain dark gray MOF-919-Cu2Co. MOF-919-Cu2Co was soaked in DMF and ethanol for 3 days each, then vacuum filtered and dried at 60°C for 12 hours. Finally, MOF-919-Cu2Co was vacuum dried at 150°C for 12 hours to obtain activated MOF-919-Cu2Co. Activated MOF-919-Cu2Co (20 mg) was dispersed in a DMF solution of PbBr2 (18.3 mg) (5 mL) and stirred for 2 hours. PbBr2@MOF-919-Cu2Co was washed by filtration with a DMF / ethanol (v:v = 1:1) mixed solvent. Then, PbBr2@MOF-919-Cu2Co was dispersed in toluene (1 mL). Meanwhile, CsBr (21.3 mg) was dispersed in methanol (10 mL) and stirred at 60°C for 1 hour. Then, the CsBr methanol solution (1 mL) was rapidly added to the PbBr2@MOF-919-Cu2Co toluene solution, and stirred at room temperature for 5 minutes.

[0044] CsPbBr3@MOF-919-Cu2Co was collected by filtration and washing with n-hexane five times to prepare CsPbBr3@MOF-919-Cu2Co.

[0045] Example 2

[0046] MOF-919-Cu3 was prepared by a hydrothermal method: ScCl3·6H2O (76.2 mg), Cu(NO3)2·3H2O (135.6 mg), 1H-pyrazole-4-carboxylic acid (H2PyC) (34.8 mg), and N,N-dimethylformamide (10 mL) were added to a 20 mL heat-resistant glass vial and heated at 100 °C for 15 hours. After cooling to room temperature, the green product was collected by filtration, soaked in DMF for 3 days, and then soaked in ethanol for 3 days. It was then vacuum dried at 60 °C for 12 hours. Finally, 20 mg of MOF-919-Cu3 was placed in…

[0047] The gray MOF-919-Cu2Zn was obtained by heating 5 mL of Zn(NO3)2·6H2O (0.5 mol / L) in DMF at 90 °C for 24 hours. MOF-919-Cu2Zn was then soaked in DMF and ethanol for 3 days each, vacuum filtered and dried at 60 °C for 12 hours, and finally vacuum dried at 150 °C for 12 hours to obtain activated MOF-919-Cu2Zn. The activated MOF-919-Cu2Zn (20 mg) was dispersed in 5 mL of PbBr2 (18.3 mg) in DMF and stirred for 2 hours.

[0048] PbBr2@MOF-919-Cu2Zn was washed by filtration with a DMF / ethanol (v:v = 1:1) mixed solvent. Then, PbBr2@MOF-919-Cu2Zn was dispersed in toluene (1 mL). Meanwhile, CsBr (21.3 mg) was dispersed in methanol (10 mL) and stirred at 60 °C for 1 hour. Then, the CsBr methanol solution (1 mL) was rapidly added to the PbBr2@MOF-919-Cu2Zn toluene solution, and the mixture was stirred at room temperature for 5 minutes.

[0049] CsPbBr3@MOF-919-Cu2Zn was collected by filtration and washing with n-hexane five times to prepare CsPbBr3@MOF-919-Cu2Zn.

[0050] Example 3

[0051] MOF-919-Cu3 was prepared by a hydrothermal method: ScCl3·6H2O (76.2 mg), Cu(NO3)2·3H2O (135.6 mg), 1H-pyrazole-4-carboxylic acid (H2PyC) (34.8 mg), and N,N-dimethylformamide (10 mL) were added to a 20 mL heat-resistant glass vial and heated at 100 °C for 15 hours. After cooling to room temperature, the green product was collected by filtration, soaked in DMF for 3 days, and then soaked in ethanol for 3 days. The product was then vacuum dried at 60 °C for 12 hours to obtain activated MOF-919-Cu3. The activated MOF-919-Cu3 (20 mg) was dispersed in a DMF solution of PbBr2 (18.3 mg) (5 mL) and stirred for 2 hours.

[0052] PbBr2@MOF-919-Cu3 was washed by filtration with a DMF / ethanol (v:v = 1:1) mixed solvent. Then, PbBr2MOF-919-Cu3 was dispersed in toluene (1 mL). Meanwhile, CsBr (21.3 mg) was dispersed in methanol (10 mL) and stirred at 60 °C for 1 hour. Then, the CsBr methanol solution (1 mL) was rapidly added to the PbBr2@MOF-919-Cu3 toluene solution, and the mixture was stirred at room temperature for 5 minutes.

[0053] CsPbBr3@MOF-919-Cu3 was collected by filtration and washing with n-hexane five times to prepare CsPbBr3@MOF-919-Cu3.

[0054] Comparative Example 1

[0055] MOF-919-Cu3 was prepared by a hydrothermal method: ScCl3·6H2O (76.2 mg), Cu(NO3)2·3H2O (135.6 mg), 1H-pyrazole-4-carboxylic acid (H2PyC) (34.8 mg), and N,N-dimethylformamide (10 mL) were added to a 20 mL heat-resistant glass vial and heated at 100 °C for 15 hours. After cooling to room temperature, the green product was collected by filtration, soaked in DMF for 3 days, and then soaked in ethanol for 3 days. It was then vacuum dried at 60 °C for 12 hours. Then, MOF-919-Cu3 (20 mg) was placed in a 5 mL solution of Co(NO3)2·6H2O (0.5 mol / L) in DMF and heated at 90 °C for 24 hours to obtain dark gray MOF-919-Cu2Co. MOF-919-Cu2Co was soaked in DMF and ethanol for 3 days, then vacuum filtered and dried at 60°C for 12 hours. Finally, MOF-919-Cu2Co was vacuum dried at 150°C for 12 hours to prepare MOF-919-Cu2Co.

[0056] Comparative Example 2

[0057] MOF-919-Cu3 was prepared by a hydrothermal method: ScCl3·6H2O (76.2 mg), Cu(NO3)2·3H2O (135.6 mg), 1H-pyrazole-4-carboxylic acid (H2PyC) (34.8 mg), and N,N-dimethylformamide (10 mL) were added to a 20 mL heat-resistant glass vial and heated at 100 °C for 15 hours. After cooling to room temperature, the green product was collected by filtration, soaked in DMF for 3 days, and then soaked in ethanol for 3 days. It was then vacuum dried at 60 °C for 12 hours. Then, MOF-919-Cu3 (20 mg) was placed in a 0.5 mol / L DMF solution (5 mL) and heated at 90 °C for 24 hours to obtain dark gray MOF-919-Cu2Co. MOF-919-Cu2Zn was soaked in DMF and ethanol for 3 days, then vacuum filtered and dried at 60°C for 12 hours. Finally, MOF-919-Cu2Zn was vacuum dried at 150°C for 12 hours to prepare MOF-919-Cu2Zn.

[0058] Comparative Example 3

[0059] MOF-919-Cu3 was prepared by a hydrothermal method: ScCl3·6H2O (76.2 mg), Cu(NO3)2·3H2O (135.6 mg), 1H-pyrazole-4-carboxylic acid (H2PyC) (34.8 mg), and N,N-dimethylformamide (10 mL) were added to a 20 mL heat-resistant glass vial and heated at 100 °C for 15 hours. After cooling to room temperature, the green product was collected by filtration, soaked in DMF for 3 days, and then soaked in ethanol for 3 days. The product was then vacuum dried at 60 °C for 12 hours to obtain MOF-919-Cu3.

[0060] Comparative Example 4

[0061] A mixture of Cs₂CO₃ (0.41 g), octadecene (ODE, 20 mL), and OA (1.3 mL) was placed in a 50 mL three-necked flask and heated at 120 °C for 1 h under an Ar atmosphere. The temperature was then raised to 150 °C and heated for 30 min to obtain a Cs-OA solution. A mixture of PbBr₂ (0.70 g), ODE (50 mL), OM (5.0 mL), and OA (5.0 mL) was placed in a 250 mL three-necked flask and heated at 120 °C for 1 h under an Ar atmosphere. The temperature was then raised to 170 °C and heated for 10 min. The prepared Cs-OA solution (4.0 mL) was then rapidly injected, and the mixture was rapidly cooled in liquid nitrogen. The sample was washed three times with ethyl acetate to obtain a yellow precipitate, followed by three washes with n-hexane to remove aggregated particles. Finally, CsPbBr₃ was obtained by washing with ethyl acetate.

[0062] Figure 1This is a schematic diagram illustrating the preparation principle of the heterojunction of the CsPbBr3@MOF-919-Cu2M (M is one of Co, Zn, or Cu) catalytic material in Examples 1-3 of this application. Figure 1 It is known that CsPbBr3 quantum dots are encapsulated in the channels of a metal-organic framework (MOF), which contains bimetallic clusters and exhibits a bimetallic synergistic effect. CsPbBr3 quantum dots, MOF-919-Cu2M, and two tightly bound metal sites within the Cu2M cluster simultaneously demonstrate synergistic catalytic activity, significantly improving the catalytic performance of CO2 photoreduction to HCOOH and H2O oxidation to O2.

[0063] Figure 2 This is the powder X-ray diffraction pattern of the CsPbBr3@MOF-919-Cu2M catalyst, from... Figure 2 It can be seen that the framework of MOF-919-Cu2M was well preserved after encapsulation with CsPbBr3 quantum dots, which is basically consistent with the simulation results (the simulation data of Simulated MOF-919-Cu3 and Simulated CsPbBr3 were obtained from DOI:10.1021 / jacs.8b11230). In addition, no characteristic peaks of CsPbBr3 powder XRD were observed in the CsPbBr3@MOF-919-Cu2M composite material, indicating that the CsPbBr3 quantum dots are small in size.

[0064] Figure 3 This is the N2 adsorption-desorption isotherm of the CsPbBr3@MOF-919-Cu2M catalyst, derived from... Figure 3 It can be seen that the N2 adsorption isotherm of MOF-919-Cu2M is a reversible type IV. After metal exchange, the N2 adsorption amount remains basically unchanged, proving that the metal replaces Cu atoms in the metal-organic framework, rather than occupying the pore positions. The N2 adsorption amount decreases significantly after encapsulating quantum dots, proving the successful encapsulation of quantum dots.

[0065] Figure 4 These are the Cs 3d and Cu 2p X-ray photoelectron spectra of the CsPbBr3@MOF-919-Cu2Co catalyst before and after photoirradiation. Figure 4 It can be seen that the Cs 3d binding energy of CsPbBr3@MOF-919-Cu2Co is positively shifted under light than in darkness, indicating that CsPbBr3 has lost electrons;

[0066] CsPbBr3@MOF-919-Cu2Co Cu 2p(Cu 2+ The binding energy of MOF-919-Cu2Co under light shows a negative shift compared to in darkness, indicating that MOF-919-Cu2Co has gained electrons.

[0067] Figure 5 This is an ultra-high resolution transmission electron microscope (TEM) image of the CsPbBr3@MOF-919-Cu2M catalyst. Figure 5 It can be seen that CsPbBr3 quantum dots are uniformly distributed in mesoporous MOF-919-Cu2M, with a size of approximately 2.0–5.0 nm.

[0068] Figure 6 This is a graph showing the change in CO2 photoreduction products over time using the CsPbBr3@MOF-919-Cu2M catalyst. Figure 6 It can be seen that the HCOOH yields of the CsPbBr3@MOF-919-Cu3, CsPbBr3@MOF-919-Cu2Zn, and CsPbBr3@MOF-919-Cu2Co composites are 151.6, 218.2, and 332.2 μmol g, respectively. -1 h -1 Compared to CsPbBr3 QDs, MOF-919-Cu3, MOF-919-Cu2Zn and MOF-919-Cu2Co, the photocatalytic performance is significantly improved.

[0069] Structural analysis was performed on the CsPbBr3@MOF-919-Cu2M catalytic material prepared above, and the results were as follows: Figure 2-4 The results are shown below; morphological analysis of the prepared CsPbBr3@MOF-919-Cu2M catalyst material yielded the following results. Figure 5 The results are shown below; the catalytic performance of the prepared CsPbBr3@MOF-919-Cu2M catalyst was tested in a CH3CN / H2O system, and the results are as follows. Figure 6 The results are shown.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a photocatalyst coupling CO2 photoreduction and H2O oxidation, characterized in that: Includes the following steps: S1: MOF-919-Cu3 was prepared by hydrothermal method, which included mixing ScCl3·6H2O, Cu(NO3)2·3H2O, 1H-pyrazole-4-carboxylic acid and solvent, heating and cooling to room temperature, filtering and soaking, and vacuum drying to obtain MOF-919-Cu3. S2: Place the MOF-919-Cu3 prepared in step S1 in a solvent containing Co(NO3)2·6H2O or Zn(NO3)2·6H2O, and heat it to obtain MOF-919-Cu2M, where M is either Co or Zn. After soaking MOF-919-Cu2M in the solvent, vacuum filter and dry it at 50-70℃ for 11-13 hours. Then, vacuum dry MOF-919-Cu2M at 140-160℃ for 11-13 hours to obtain activated MOF-919-Cu2M. S3: The activated MOF-919-Cu2M was mixed and stirred with a DMF solution of PbBr2 to obtain PbBr2@MOF-919-Cu2M. The PbBr2@MOF-919-Cu2M was washed with a solvent and dispersed in a solvent to obtain a PbBr2@MOF-919-Cu2M solution. CsBr solution was added to the PbBr2@MOF-919-Cu2M solution and stirred. CsPbBr3@MOF-919-Cu2M was filtered and washed to obtain CsPbBr3@MOF-919-Cu2M. In step S3, the mass ratio of MOF-919-Cu2M, PbBr2 and CsBr is 1:0.9-0.1:1-1.

1.

2. The method for preparing the photocatalyst coupled with CO2 photoreduction and H2O oxidation according to claim 1, characterized in that: In step S1, ScCl3·6H2O, Cu(NO3)2·3H2O, 1H-pyrazole-4-carboxylic acid are mixed with a solvent, N,N-dimethylformamide.

3. The method for preparing the photocatalyst coupled with CO2 photoreduction and H2O oxidation according to claim 2, characterized in that: In step S1, the heating temperature is 90-110℃, and the heating time is 14-16 hours.

4. The method for preparing the photocatalyst coupled with CO2 photoreduction and H2O oxidation according to claim 2, characterized in that: The soaking process after filtration in step S1 includes soaking in DMF for 2-4 days, followed by soaking in ethanol for 2-4 days.

5. The method for preparing the photocatalyst coupled with CO2 photoreduction and H2O oxidation according to claim 2, characterized in that: In step S1, vacuum drying is performed at 50-70℃ for 11-13 hours.

6. The method for preparing the photocatalyst coupled with CO2 photoreduction and H2O oxidation according to claim 1, characterized in that: In step S1, the molar ratio of ScCl3·6H2O, Cu(NO3)2·3H2O, and 1H-pyrazole-4-carboxylic acid is 1:2~2.6:1.3~1.7; In step S2, the solvent for Co(NO3)2·6H2O or Zn(NO3)2·6H2O is DMF.

7. The method for preparing the photocatalyst coupled with CO2 photoreduction and H2O oxidation according to claim 1, characterized in that: In step S2, the concentration of Co(NO3)2·6H2O is 0.5 mol / L, and the concentration of Zn(NO3)2·6H2O is 0.5 mol / L.

8. The method for preparing the photocatalyst coupled with CO2 photoreduction and H2O oxidation according to claim 7, characterized in that: The heating temperature for obtaining MOF-919-Cu2M after heating in step S2 is 80-100℃.

9. The method for preparing the photocatalyst coupled with CO2 photoreduction and H2O oxidation according to claim 7, characterized in that: In step S2, MOF-919-Cu2M is soaked in DMF and ethanol for 2-4 days respectively.

10. The method for preparing the photocatalyst coupled with CO2 photoreduction and H2O oxidation according to claim 1, characterized in that: In step S3, the activated MOF-919-Cu2M and the DMF solution of PbBr2 are mixed and stirred for 1-3 hours.

11. The method for preparing the photocatalyst coupled with CO2 photoreduction and H2O oxidation according to claim 1, characterized in that: In step S3, PbBr2@MOF-919-Cu2M is washed in a mixed solution of DMF and ethanol.

12. The method for preparing the photocatalyst coupled with CO2 photoreduction and H2O oxidation according to claim 11, characterized in that: The volume ratio of DMF to ethanol is 1:

1.

13. The method for preparing the photocatalyst coupled with CO2 photoreduction and H2O oxidation according to claim 12, characterized in that: PbBr2@MOF-919-Cu2M was dispersed in toluene, and the solvent for the CsBr solution was methanol. The CsBr solution was added to the toluene solution of PbBr2@MOF-919-Cu2M and stirred at room temperature for 4-6 minutes. CsPbBr3@MOF-919-Cu2M was collected after filtration and washing with n-hexane several times.

14. The catalyst prepared by the method of any one of claims 1 to 13, wherein the photocatalyst is coupled with CO2 photoreduction and H2O oxidation, is characterized in that: CsPbBr3 quantum dots are uniformly distributed in mesoporous MOF-919-Cu2M, with CsPbBr3 sizes ranging from 2.0 to 5.0 nm.

15. The catalyst prepared by the method of any one of claims 1-13 for the coupling of CO2 photoreduction and H2O oxidation is applied to the photocatalytic CO2 reduction reaction.

16. The application according to claim 15, characterized in that: The solution for the photocatalytic CO2 reduction reaction is CH3CN and H2O.

17. The application according to claim 16, characterized in that: The photocatalytic CO2 reduction reaction uses light intensity of 250~350mW·cm. -2 A xenon lamp is used as the illumination source, and the λ of the xenon lamp is ≥ 420 nm.

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