A high-efficiency carrier separation photocatalyst based on a metal organic framework material and a preparation method thereof
By loading Pt nanoparticles inside MOF materials and growing Cu-TCPP MOF heterojunctions, the problems of low light absorption and carrier separation efficiency of photocatalysts were solved, achieving efficient CO2 reduction and product selectivity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-02-05
- Publication Date
- 2026-03-24
AI Technical Summary
Existing photocatalysts have poor absorption of visible light, low efficiency in separating photogenerated electrons and holes, and few active sites, resulting in low catalytic performance.
Pt nanoparticles were loaded inside MOF materials, and two-dimensional Cu-TCPP MOFs were grown in situ on their surface to construct heterojunctions to improve carrier separation efficiency and light absorption performance.
It improves the carrier separation efficiency and visible light utilization of the photocatalyst, enhances the catalytic reaction rate and product selectivity, and improves CO2 reduction efficiency.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of photocatalysts, in particular to a high-efficiency carrier separation photocatalyst based on metal-organic framework materials and a preparation method thereof. BACKGROUND
[0002] The dependence of human beings on fossil fuels has led to energy shortages and global warming caused by excessive emissions of CO2. Converting CO2 into valuable chemicals such as CO, CH3OH, CH4, C2H4, C2H6, etc. can not only solve environmental problems by utilizing CO2 as a resource, but also solve energy problems. Among numerous CO2 conversion technologies, photocatalytic CO2 reduction technology using sunlight as the only energy source has become a key research direction in recent years. However, most catalysts for photocatalytic reduction of carbon dioxide have poor visible light absorption, low separation efficiency of photo-generated electrons and holes, and few active sites of the catalyst, so the catalytic performance is still low.
[0003] Metal-organic framework compounds (MOFs) are crystalline materials with periodic network structure formed by connecting metal nodes (metal ions or metal clusters) and organic ligands through coordination bonds. Because of its adjustable chemical composition, open catalytic sites, high porosity, good affinity for CO2, and can be excited by light, etc., it is widely used in photocatalytic reactions. However, the single MOF catalyst has a very low catalytic efficiency because the electrons and holes are easily and quickly recombined. On the one hand, because the noble metals Pt and Pd have strong affinity for electrons, encapsulating Pt, Pd, etc. inside the MOF to construct a heterostructure can effectively reduce the recombination of electrons and holes. On the other hand, constructing MOF-on-MOF heterojunction can enhance the separation efficiency of photo-generated carriers and adjust the electronic structure of MOFs materials, thereby greatly improving the photocatalytic performance. SUMMARY
[0004] The present invention aims to provide a highly efficient carrier separation photocatalyst based on a metal-organic framework (MOF) material and its preparation method. The invention first loads Pt nanoparticles inside a MOF material while ensuring that the crystallinity and morphology of the MOF remain unchanged. Subsequently, a two-dimensional Cu-TCPP MOF layer is grown in situ on the surface of the Pt nanoparticle-loaded MOF, constructing a heterojunction capable of efficiently separating carriers, while simultaneously improving the light absorption performance and stability of the composite material. Furthermore, the composite catalyst designed in this invention allows for better CO2 enrichment by the MOF material, facilitating reduction on the Pt nanoparticles; and the Cu-TCPP MOF grown in situ on the Pt nanoparticle-loaded MOF surface enables more efficient mass transfer, thereby increasing the rate of the catalytic reaction.
[0005] To achieve the above objectives, the present invention provides the following technical solution:
[0006] The efficient carrier separation photocatalyst based on metal-organic framework materials includes: loading Pt nanoparticles inside a three-dimensional MOF, and growing a two-dimensional Cu-TCPP MOF in situ on the surface of the MOF loaded with Pt nanoparticles, thus constructing a heterojunction that can efficiently separate carriers.
[0007] The method for preparing a highly efficient carrier separation photocatalyst based on metal-organic framework materials is characterized by comprising the following steps:
[0008] (1) Preparation of Pt nanoparticles;
[0009] (2) Pt nanoparticles are dispersed in the growth solution for preparing NH2-UiO-66, so that Pt nanoparticles are loaded inside the crystal of NH2-UiO-66 during the growth of NH2-UiO-66.
[0010] (3) NH2-UiO-66 loaded with Pt nanoparticles was dispersed in a solution and ultrasonically dispersed; copper salt for preparing two-dimensional Cu-TCPP MOF and TCPP solution were slowly added, and the mixture was stirred and heated in an oil bath to obtain a high-efficiency carrier separation photocatalyst of metal-organic framework material.
[0011] The Pt nanoparticles mentioned in step (1) are approximately 3 nanometers in size. The preparation method includes the following steps: dissolving chloroplatinic acid and polyvinylpyrrolidone in ethylene glycol and stirring, transferring the solution to a reaction vessel, cooling to room temperature after the reaction, adding acetone to precipitate, washing, centrifuging, and redispersing in N,N-dimethylformamide. Each 0.1 mole of chloroplatinic acid corresponds to 60–80 mg of polyvinylpyrrolidone, 20–40 mL of ethylene glycol, and 60–80 mL of acetone. The reaction temperature is 100–150 °C, and the reaction time is 10 minutes.
[0012] In step (2), Pt nanoparticles are loaded inside NH2-UiO-66 crystals. The dispersion of Pt nanoparticles is added to an N,N-dimethylformamide solution of aminoterephthalic acid and zirconium chloride, acetic acid is added, and then the reaction is carried out at 120°C for 12 hours. After the reaction is completed, the mixture is cooled to room temperature, washed, and dried. Each 0.3 mg of Pt nanoparticles corresponds to 0.2-0.3 mmol of zirconium chloride, 5-10 mL of acetic acid, and 0.3-0.6 mmol of aminoterephthalic acid.
[0013] Step (3) specifically includes the following steps:
[0014] (a) Weigh the Pt@NH2-UiO-66 prepared in step (2) and disperse it in a mixed solution of N,N-dimethylformamide and ethanol in a volume ratio of 3:1, and preheat it to 80°C.
[0015] (b) Weigh 10-15 mg of copper nitrate trihydrate, 60-90 mg of polyvinylpyrrolidone and 3-5 mg of pyrazine and dissolve them in a mixed solution of N,N-dimethylformamide and ethanol in a volume ratio of 3:1 to obtain solution 1; weigh 5 mg of TCPP and dissolve it in a mixed solution of N,N-dimethylformamide and ethanol in a volume ratio of 3:1 to obtain solution 2;
[0016] (c) The two solutions from (b) were slowly added dropwise to the Pt@NH2-UiO-66 dispersion from step (a), and the reaction was heated at 80°C for 3 hours. After the reaction was completed, the mixture was cooled to room temperature, centrifuged, and the product was washed with ethanol and dried.
[0017] In the above steps, each 2 mg of Pt@NH2-UiO-66 in solution 1 corresponds to 10-15 mg of copper nitrate trihydrate, 60-90 mg of polyvinylpyrrolidone, and 3-5 mg of pyrazine, while solution 2 contains 8-10 mg of pyrazine.
[0018] The application of highly efficient carrier separation photocatalysts based on metal-organic framework materials for the photocatalytic reduction of carbon dioxide to carbon monoxide.
[0019] Reaction conditions: The catalyst was added to a mixed solution of water and triethylamine (preferably in a volume ratio of 1:1). A 300W xenon lamp was used as the light source for the photocatalytic experiment. Carbon dioxide gas was introduced. The reaction was first balanced in the dark for one hour at a reaction pressure of 0.1 MPa, and then the photocatalytic reaction was carried out.
[0020] This invention loads Pt nanoparticles inside a MOF crystal, resulting in a MOF crystal that retains good crystallinity and octahedral morphology. Due to the excellent electrical conductivity of Pt nanoparticles, they can act as active centers in catalytic reactions, and the MOF can better enrich CO2. Furthermore, a two-dimensional Cu-MOF layer is grown on the Pt-loaded MOF. The Pt-loaded MOF can form a heterojunction structure with the externally grown Cu-MOF, which facilitates efficient separation of photogenerated carriers, improves the visible light utilization efficiency of the catalyst, and the ultrathin structure of the two-dimensional Cu-MOF further enhances the mass transfer rate during the catalytic reaction, thereby further improving the catalytic activity. In addition, this invention allows for control of the thickness of the external Cu-TCPP MOF by adjusting the loading amount of Pt nanoparticles and the growth time of the external Cu-TCPP MOF, enabling selective regulation of the product.
[0021] Meanwhile, this invention also provides a feasibility for developing photocatalytic hydrogen evolution catalysts, which can achieve efficient photocatalytic hydrogen evolution by adjusting the loading of Pt nanoparticles on MOF.
[0022] The preparation method provided by this invention is simple, easy to implement, has a high yield, and is easy to mass-produce. Attached Figure Description
[0023] Figure 1 X-ray powder diffraction patterns of NH2-UiO-66, Pt@NH2-UiO-66, Cu-TCPP MOF and Pt@NH2-UiO-66@Cu-TCPP MOF.
[0024] Figure 2 Transmission electron microscopy (TEM) image of Pt@NH2-UiO-66@Cu-TCPP MOF.
[0025] Figure 3 Catalytic activity diagrams of NH2-UiO-66, Pt@NH2-UiO-66, and Pt@NH2-UiO-66@Cu-TCPP MOFs for carbon dioxide under dark and light conditions. Detailed Implementation
[0026] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.
[0027] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0028] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.
[0029] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0030] Example 1
[0031] Pt@NH 2- Preparation of UiO-66@Cu-TCPP MOF complex:
[0032] (1) Weigh 200 mg of polyvinylpyrrolidone and 40.16 mg of chloroplatinic acid and dissolve them in 20 mL of ethylene glycol. Transfer the solution to a flask and heat at 180 °C for 10 minutes. After the reaction is complete, cool to room temperature and add 80 mL of acetone until a precipitate forms. Centrifuge and wash the precipitate. Redisperse the Pt nanoparticles obtained from the reaction in N,N-dimethylformamide for later use.
[0033] (2) Dissolve 0.263 mmol zirconium chloride and 0.52 mmol aminoterephthalic acid in 60 mL N,N-dimethylformamide and stir until fully dissolved. Then add 0.3 mL (0.3 mg Pt nanoparticles) of the Pt nanoparticle dispersion prepared in (1), add 7 mL acetic acid, stir for 0.5 hours, heat to 120 °C and react for 12 hours. After the reaction is completed, cool to room temperature, wash with N,N-dimethylformamide, and dry in a vacuum oven at 60 °C.
[0034] (3) Weigh 2 mg of Pt@NH2-UiO-66 prepared in step (2) and disperse it in a mixed solution of N,N-dimethylformamide and ethanol in a volume ratio of 3:1. Transfer the dispersion to a 25 mL round-bottom flask and preheat it at 80 °C for 10 minutes for later use.
[0035] (4) Weigh 13 mg of copper nitrate trihydrate, 60 mg of polyvinylpyrrolidone and 3 mg of pyrazine, and dissolve them in 6 mL of a mixed solution of N,N-dimethylformamide and ethanol in a volume ratio of 3:1; weigh 10 mg of TCPP and dissolve it in 5 mL of a mixed solution of N,N-dimethylformamide and ethanol in a volume ratio of 3:1.
[0036] (5) The two solutions in (4) were slowly added dropwise to the Pt@NH2-UiO-66 dispersion in step (3) at a rate of 0.25 mL / h. The reaction was kept at 80°C for 3 h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged and washed with ethanol. The product was then dried under vacuum at 60°C for 12 h.
[0037] The X-ray powder diffraction pattern of the Pt@NH2-UiO-66@Cu-TCPP MOF composite obtained in Example 1 is shown in Figure 1. Figure 1 .
[0038] The transmission electron microscopy (TEM) image of the Pt@NH2-UiO-66@Cu-TCPP MOF composite obtained in Example 1 is shown below. Figure 2 .
[0039] Weigh out 1 mg of catalyst, 100 μL of water, and 100 μL of triethylamine. Use a 300 W xenon lamp as the light source for the photocatalytic experiment, and purge with high-purity (999.99%) carbon dioxide gas. After rinsing ten times, use the purified gas as the reaction gas. First, equilibrate in the dark for one hour at a reaction pressure of 0.1 MPa, and then irradiate with light (150 mW / cm²). 2 Samples were taken at 2, 4, 6 and 8 hours, and the results were analyzed by gas chromatography.
[0040] The catalysts used were NH2-UiO-66, Pt@NH2-UiO-66, and Pt@NH2-UiO-66@Cu-TCPP MOF materials obtained in Example 1, respectively. The products at different time points were analyzed using an Agilent gas chromatograph. The percentage of CO gas in the total gas content was substituted into PV = nRT (where V represents the total reactor volume of 0.05 m³). 3 The calculated CO production results are shown in the figure. Figure 3 ,from Figure 3 As can be seen from the data, the Pt@NH2-UiO-66@Cu-TCPP MOF catalyst has the highest CO yield.
[0041] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims
1. An application of a highly efficient carrier separation photocatalyst based on metal-organic framework materials for the photocatalytic reduction of carbon dioxide to carbon monoxide; The method for preparing the catalyst includes the following steps: (1) Preparation of Pt nanoparticles; (2) Pt nanoparticles are dispersed in the growth solution for preparing NH2-UiO-66, so that Pt nanoparticles are loaded inside the crystal of NH2-UiO-66 during the growth of NH2-UiO-66; (3) NH2-UiO-66 loaded with Pt nanoparticles was dispersed in the solution and ultrasonically dispersed; copper salt for preparing two-dimensional Cu-TCPP MOF and TCPP solution were slowly added and stirred and heated in an oil bath to obtain a high-efficiency carrier separation photocatalyst of metal-organic framework material. The Pt nanoparticles mentioned in step (1) are 3 nanometers in size; the preparation method includes the following steps: dissolving chloroplatinic acid and polyvinylpyrrolidone in ethylene glycol and stirring, transferring the solution to a reaction vessel, cooling to room temperature after the reaction is completed, adding acetone to precipitate, washing, centrifuging, and redispersing in N,N-dimethylformamide; each 0.1 mole of chloroplatinic acid corresponds to 60~80 mg of polyvinylpyrrolidone, 20~40 mL of ethylene glycol, and 60~80 mL of acetone, the reaction temperature is 100~150 °C, and the reaction time is 10 minutes; In step (2), the Pt nanoparticles are loaded inside the NH2-UiO-66 crystals. The dispersion of Pt nanoparticles is added to an N,N-dimethylformamide solution of aminoterephthalic acid and zirconium chloride, acetic acid is added, and then the reaction is carried out at 120°C for 12 hours. After the reaction is completed, the mixture is cooled to room temperature, washed, and dried. Each 0.3 mg of Pt nanoparticles corresponds to 0.2~0.3 mmol of zirconium chloride, 5~10 mL of acetic acid, and 0.3~0.6 mmol of aminoterephthalic acid.
2. The application according to claim 1, characterized in that, Step (3) specifically includes the following steps: (a) Weigh the Pt@NH2-UiO-66 prepared in step (2) and disperse it in a mixed solution of N,N-dimethylformamide and ethanol in a volume ratio of 3:1, and preheat it to 80 °C; (b) Weigh 10-15 mg of copper nitrate trihydrate, 60-90 mg of polyvinylpyrrolidone and 3-5 mg of pyrazine and dissolve them in a mixed solution of N,N-dimethylformamide and ethanol in a volume ratio of 3:1 to obtain solution 1; Weigh 5 mg of TCPP and dissolve it in a mixed solution of N,N-dimethylformamide and ethanol in a volume ratio of 3:1 to obtain solution 2; (c) The two solutions in (b) were slowly added dropwise to the Pt@NH2-UiO-66 dispersion in step (a) and the reaction was heated at 80 °C for 3 h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged, washed with ethanol, and dried. In the above steps, each 2 mg of Pt@NH2-UiO-66 in solution 1 corresponds to 10~15 mg of copper nitrate trihydrate, 60~90 mg of polyvinylpyrrolidone, and 3~5 mg of pyrazine.
3. According to the application of claim 1, the reaction conditions are as follows: the catalyst is added to a mixed solution of water and triethylamine at a volume ratio of 1:1, a 300W xenon lamp is used as the light source for the photocatalytic experiment, carbon dioxide gas is introduced, the reaction is first balanced in the dark for one hour, the reaction pressure is 0.1 MPa, and then the photocatalytic reaction is carried out.