Method for the preparation of ordered defective indium cluster framework porous materials for electrocatalytic conversion of carbon dioxide to urea

Abstract

The application relates to a preparation method of an ordered defective indium cluster framework porous material for electrocatalytic reduction of carbon dioxide to urea, and belongs to the technical equipment field of ordered defective metal organic framework synthesis, in particular to a preparation method of an ordered defective indium cluster framework material for electrocatalytic reduction of CO2 to urea, which comprises a preparation method of five steps; through the above design, the ordered defective indium cluster framework porous material is synthesized by adopting a hydrothermal synthesis mode, taking indium trifluoromethyl sulfonate as a metal source and a square fan of in-situ self-assembly; the preparation method of the application can obtain the ordered defective indium cluster framework porous material, the obtained product indium cluster framework porous material has uniform micron-level size and excellent stability, the method used in the application is simple in operation, the obtained catalyst defect order exhibits excellent selectivity in electrocatalytic reduction of carbon dioxide to urea at a lower overpotential, which is difficult to realize by the existing metal organic framework-based catalyst.

Description

Technical Field

[0001] This invention belongs to the field of technology and equipment for the synthesis of ordered defective metal-organic frameworks, and specifically relates to a method for preparing ordered defective indium cluster framework materials for the electrocatalytic reduction of CO2 to urea. Background Technology

[0002] Converting the greenhouse gas carbon dioxide into high-value chemicals via electrochemical reduction is an effective solution to alleviate the energy crisis. Carbon dioxide reduction involves the conversion of carbon dioxide into single-carbon products (carbon monoxide, formic acid, methane, etc.) and multi-carbon products (ethanol, acetic acid, ethylene, etc.) through the use of 2-12 electrons. Despite significant progress in carbon dioxide reduction, the products generated remain largely limited to single-C or C-C coupling chemicals. Exploring new pathways for electrocatalytic carbon dioxide reduction has become a crucial task in the field of electrocatalysis, aiming to diversify the products generated from carbon dioxide. Currently, the electrocatalytic synthesis of valuable CN-C coupling compounds (urea) from carbon dioxide and nitrogen-containing species (nitrates) discarded on Earth has been successful, expanding the product range beyond pure carbon dioxide reduction. Furthermore, urea has significant applications in agriculture, chemical synthesis, and medicinal chemistry.

[0003] Metal-organic frameworks (MOFs) are widely used in electrocatalytic carbon dioxide reduction due to their high specific surface area, flexible and tunable structure, and ease of functionalization. Common strategies such as doping, acidification, and pyrolysis are employed to construct defects and enhance the catalytic activity of these materials. However, the preparation of defects in MOF materials is random, making precise defect construction in MOFs difficult.

[0004] Therefore, a new technical solution is urgently needed to solve this problem in the existing technology. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an optimized upgrade for components existing in the background art.

[0006] A method for preparing an ordered defect-type indium cluster framework porous material for electrocatalytic conversion of carbon dioxide to urea, characterized by comprising the following steps, which are performed sequentially:

[0007] Step 1: Weigh the metal salt, which is indium trifluoromethanesulfonate. Place the weighed metal salt into the polytetrafluoroethylene liner of the high-pressure reactor.

[0008] Step 2: Weigh the organic ligand, which is an asymmetric organic ligand, and place the weighed ligand into the polytetrafluoroethylene liner of the high-pressure reactor.

[0009] Step 3: Place the organic solvent into the polytetrafluoroethylene liner of the high-pressure reactor and stir at room temperature for 2 hours;

[0010] Step 4: Tighten the high-pressure reactor from Step 3 and place it in an oven. Heat the oven to 80-120°C and react at 80-120°C for 48 hours. Then, let the oven cool down naturally to 10-25°C to obtain an ordered defect type indium cluster framework porous material.

[0011] Step 5: Rinse the ordered defect type indium cluster framework porous material generated in Step 4 with deionized water and acetonitrile, and place it in a centrifuge tube to air dry naturally to obtain a pure ordered defect type indium cluster framework porous material.

[0012] In step two, the amount of organic ligand used is half the mass of the metal salt.

[0013] The coordination asymmetric organic ligands include isonicotinic acid and isophthalic acid, both of which have a substituent at the 2-position of the benzene ring.

[0014] The isonicotinic acids with a substituent at the 2-position of the benzene ring include: isonicotinic acid, 2-aminoisonicotinic acid, 2-methylisonicotinic acid, 2-hydroxyisonicotinic acid, 2-chloroisonicotinic acid, 2-bromoisonicotinic acid, etc.

[0015] The organic solvents used in step three are mainly acetonitrile and N,N-dimethylformamide.

[0016] Through the above design, this application uses indium trifluoromethanesulfonate as the metal source for hydrothermal synthesis and in-situ self-assembly to synthesize ordered defective indium cluster framework porous materials. The preparation method of this application can produce ordered defective indium cluster framework porous materials. The obtained indium cluster framework porous materials have uniform micron-sized dimensions and excellent stability. The method used in this application is simple to operate, and the obtained catalyst has ordered defects. It exhibits excellent selectivity in the electrocatalytic reduction of carbon dioxide to urea at a low overpotential, which is difficult to achieve with existing metal-organic framework-based catalysts. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0018] Figure 1 1. Lower dimension of the ordered defect type indium cluster framework porous material prepared by the invention at 200 μm;

[0019] Figure 2 Figure 1 shows a comparison of the LSV curves of the present invention under a CO2 / Ar atmosphere;

[0020] Figure 3 Figure 1 shows the product distribution of the present invention at different potentials;

[0021] Figure 4 Figure 1 shows a comparison of urea products under a CO2 / Ar atmosphere according to the present invention.

[0022] Figure 5 The present invention 15 N NMR. Detailed Implementation

[0023] This application will be further described in conjunction with the accompanying drawings:

[0024] A method for preparing an ordered defect-type indium cluster framework porous material for electrocatalytic CO2 conversion to urea, characterized by comprising the following steps, which are performed sequentially:

[0025] Step 1: Weigh the metal salt, which includes indium trifluoromethanesulfonate, and place the weighed metal salt into the polytetrafluoroethylene liner of the high-pressure reactor.

[0026] Step 2: Weigh the organic ligand, which is an asymmetric organic ligand, and place the weighed ligand into the polytetrafluoroethylene liner of the high-pressure reactor.

[0027] Step 3: Place the organic solvent into the polytetrafluoroethylene liner of the high-pressure reactor and stir at room temperature for 2 hours;

[0028] Step 4: Tighten the high-pressure reactor from Step 3 and place it in an oven. Heat the oven to 80-120°C and react at 80-120°C for 48 hours. Then, let the oven cool down naturally to 10-25°C to obtain an ordered defect type indium cluster framework porous material.

[0029] Step 5: Rinse the ordered defect type indium cluster framework porous material generated in Step 4 with deionized water and acetonitrile, and place it in a centrifuge tube to air dry naturally to obtain a pure ordered defect type indium cluster framework porous material.

[0030] In step two, the amount of organic ligand used is half the mass of the metal salt.

[0031] The coordination asymmetric organic ligands include isonicotinic acid and isophthalic acid, both of which have a substituent at the 2-position of the benzene ring.

[0032] The isonicotinic acids with a substituent at the 2-position of the benzene ring include: isonicotinic acid, 2-aminoisonicotinic acid, 2-methylisonicotinic acid, 2-hydroxyisonicotinic acid, 2-chloroisonicotinic acid, 2-bromoisonicotinic acid, etc.

[0033] The organic solvents used in step three are mainly acetonitrile and N,N-dimethylformamide.

[0034] Example 1

[0035] Accurately weigh 15 mg of indium trifluoromethanesulfonate and 7.5 mg of isonicotinic acid ligand, and place them in the polytetrafluoroethylene (PTFE) liner of a high-pressure reactor. Add 3 ml of acetonitrile (AR) and stir for 2 h. Tighten the PTFE liner in the high-pressure reactor, place the reactor in an oven, heat the oven to 80 °C, and react at 80 °C for 48 h. Then allow the oven to cool naturally to 10 °C. Wash the synthesized ordered defect MOF alternately with 3 ml of deionized water and 3 ml of acetonitrile, and place the washed crystals in 2 ml centrifuge tubes to air dry. The morphology of the prepared ordered defect MOF is shown in the figure. Figure 1 As shown.

[0036] Example 2:

[0037] Accurately weigh 20 mg of indium trifluoromethanesulfonate and 10 mg of ligand 2-chloroisonicotinic acid into the polytetrafluoroethylene liner of a high-pressure reactor. Add 5 ml of acetonitrile (AR) and stir for 2 h. Tighten the polytetrafluoroethylene liner in the high-pressure reactor. Place the high-pressure reactor in an oven and heat it to 120 °C. React at 120 °C for 48 h. Then, allow the oven to cool naturally to 25 °C. Wash the synthesized ordered defect MOF alternately with 3 ml of deionized water and 3 ml of acetonitrile. Place the washed crystals into 2 ml centrifuge tubes and air dry naturally.

[0038] Example 3:

[0039] Accurately weigh 16 mg of indium trifluoromethanesulfonate and 8 mg of ligand 2-hydroxyisonicotinic acid into a polytetrafluoroethylene (PTFE) liner in a high-pressure reactor. Add 3.5 ml of acetonitrile (AR) and stir for 2 h. Tighten the PTFE liner in the high-pressure reactor. Place the reactor in an oven and heat it to 100 °C. React at 100 °C for 48 h. Then allow the oven to cool naturally to 10 °C. Wash the synthesized ordered defect MOF alternately with 3 ml of deionized water and 3 ml of acetonitrile. Place the washed crystals into 2 ml centrifuge tubes and air dry naturally.

[0040] Example 4:

[0041] Accurately weigh 16 mg of indium trifluoromethanesulfonate and 8 mg of ligand 2-aminoisonicotinic acid into a polytetrafluoroethylene (PTFE) liner in a high-pressure reactor. Add 4 ml of acetonitrile (AR) and stir for 2 h. Tighten the PTFE liner in the high-pressure reactor. Place the reactor in an oven and heat it to 100 °C. React at 100 °C for 48 h. Then allow the oven to cool naturally to 25 °C. Wash the synthesized ordered defect MOF alternately with 3 ml of deionized water and 3 ml of acetonitrile. Place the washed crystals into 2 ml centrifuge tubes and air dry naturally.

[0042] Example 5:

[0043] Accurately weigh 20 mg of indium trifluoromethanesulfonate and 10 mg of ligand 2-bromoisonicotinic acid into a polytetrafluoroethylene (PTFE) liner in a high-pressure reactor. Add 5 ml of acetonitrile (AR) and stir for 2 h. Tighten the PTFE liner in the high-pressure reactor. Place the reactor in an oven and heat it to 120 °C. React at 120 °C for 48 h. Then allow the oven to cool naturally to 25 °C. Wash the synthesized ordered defect MOF alternately with 3 ml of deionized water and 3 ml of acetonitrile. Place the washed crystals into 2 ml centrifuge tubes and air dry.

[0044] Example 6:

[0045] Accurately weigh 20 mg of indium trifluoromethanesulfonate and 10 mg of isophthalic acid ligand, and place them in the polytetrafluoroethylene liner of a high-pressure reactor. Add 5 ml of N,N-dimethylformamide (AR) and stir for 2 h. Tighten the polytetrafluoroethylene liner in the high-pressure reactor, place the reactor in an oven, heat the oven to 120 °C, and react at 120 °C for 48 h. Then, allow the oven to cool naturally to 25 °C. Wash the synthesized ordered defect MOF alternately with 3 ml of deionized water and 3 ml of acetonitrile, and place the washed crystals in 2 ml centrifuge tubes to air dry naturally.

[0046] This invention is simple to operate and generates in-situ ordered defect-type indium cluster framework porous materials. Figure 1 Taking the structure shown as an example, it has excellent selectivity for the electrocatalytic reduction of carbon dioxide to produce urea at a low overpotential. Using potassium bicarbonate containing 1 mg / ml KNO3 as the electrolyte, CO2 can be converted into urea at a voltage of -0.4 V vs RHE, with a carbon product selectivity of 100%.

[0047] The activity of a porous material containing a defective indium cluster framework for urea electrosynthesis was evaluated in a CO2-saturated solution containing 1 mg / ml of 0.1 M KHCO3. Figure 2 As shown, compared to the Ar environment, the overpotential is significantly reduced and the current density is significantly increased in the CO2 atmosphere, indicating that it has the ability to produce urea from CO2.

[0048] like Figure 3 As shown, the prepared urea product exhibits a volcanic distribution. At -0.4V vs RHE, the maximum selectivity for urea is observed to be 70%, and the carbon selectivity for CO2 is 100%, which is one of the reported values ​​for electrocatalysts.

[0049] To further evaluate the source of urea, control experiments and isotope experiments were conducted to demonstrate the successful preparation of urea.

[0050] The ordered defect type indium cluster framework porous material catalyst obtained in this application has a low overpotential and high selectivity in the catalytic reduction of CO2 to prepare urea. At a potential of -0.4V vs RHE, it can convert CO2 into urea with a carbon product selectivity of 100%.

[0051] Figure 1 Images of the product of this application at a size of 200µm.

Claims

1. A method for preparing an ordered defect-type indium cluster framework porous material for electrocatalytic conversion of carbon dioxide to urea, characterized in that: The steps are as follows, and they are performed in sequence: Step 1: Weigh the metal salt, which includes indium trifluoromethanesulfonate, and place the weighed metal salt into the polytetrafluoroethylene liner of the high-pressure reactor. Step 2: Weigh the organic ligand, which is one of the following: isonicotinic acid, 2-aminoisonicotinic acid, 2-methylisonicotinic acid, 2-hydroxyisonicotinic acid, 2-chloroisonicotinic acid, and 2-bromoisonicotinic acid. Place the weighed ligand into the polytetrafluoroethylene liner of the high-pressure reactor. The amount of organic ligand used is half the mass of the metal salt. Step 3: Place the organic solvent into the polytetrafluoroethylene liner of the high-pressure reactor and stir at room temperature for 2 hours; Step 4: Tighten the high-pressure reactor from Step 3 and place it in an oven. Heat the oven to 80-120°C and react at 80-120°C for 48 hours. Then, let the oven cool down naturally to 10-25°C to obtain an ordered defect type indium cluster framework porous material. Step 5: Rinse the ordered defect type indium cluster framework porous material generated in Step 4 with deionized water and acetonitrile, and place it in a centrifuge tube to air dry naturally to obtain a pure ordered defect type indium cluster framework porous material.

2. The method for preparing the ordered defect-type indium cluster framework porous material for electrocatalytic conversion of carbon dioxide to urea according to claim 1, characterized in that: The organic solvents used in step three are acetonitrile and N,N-dimethylformamide.

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