Carbon cloth loaded nonmetal covalent organic framework material catalyst electrode and preparation method and application thereof
By using the carbon cloth-supported MOF and COF composite structure in the electrocatalyst, the problems of insufficient activity and short life of the existing electrocatalyst are solved, and efficient and stable urea synthesis is achieved.
Patent Information
- Application Number
- CN202510179559.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-19
- Publication Date
- 2025-04-18
- Estimated Expiration
- 2045-02-19
AI Technical Summary
In the electrochemical synthesis of urea, existing electrocatalysts have problems such as insufficient catalytic activity, poor selectivity and short life, which affects the efficient output of urea.
The catalyst powder was synthesized by a carbon cloth-supported MOF and COF composite enamine structure porous organic frame material COF/MOF electrode through solvothermal strategy and combined with the carbon cloth to form a composite electrode.
High Faraday efficiency and urea yield in the electrochemical synthesis of urea are achieved, and the catalyst exhibits good electrocatalytic activity and stability.
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Figure CN119843306A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of electrocatalysis, and in particular relates to a carbon cloth-supported non-metallic covalent organic framework material catalyst electrode, a preparation method thereof, and an application thereof in electrochemical synthesis of urea. Background Art
[0002] Compared with the traditional Haber-Bosch process, the electrochemical synthesis of urea technology has shown significant environmental and economic benefits. This technology can be carried out at lower temperatures and pressures, reducing energy consumption and equipment costs, while reducing dependence on fossil fuels and reducing greenhouse gas emissions. The electrochemical synthesis of urea process is carried out at room temperature and pressure, making it possible to use renewable energy such as solar energy or wind energy, further promoting environmental sustainability. In addition, the process produces fewer by-products, simplifies the waste treatment process and reduces costs. The process of electrochemical synthesis of urea is flexible, and the output can be adjusted according to demand, which is suitable for small-scale or distributed production. The development of this technology has also promoted technological innovation in related fields of the chemical industry such as electrocatalyst materials, opening up a new path for sustainable development. The key to achieving efficient urea production lies in the development of electrocatalysts with high catalytic activity, good selectivity and long life. In recent years, a new method for synthesizing urea by electrocatalytic CN coupling of nitrogen-containing waste and carbon dioxide has attracted widespread attention. This method has obvious advantages such as low energy consumption, simple operation, clean and environmentally friendly. The enaminone structure composed of MOF and COF synthesized by the present invention is an emerging composite functional material and has attracted wide attention in the field of electrosynthesis of urea. Summary of the invention
[0003] The purpose of the present invention is to provide a COF / MOF electrode of an enaminone structure organic framework material composited with MOF and COF supported by carbon cloth, which has simple raw materials, convenient synthesis, stable performance and good selectivity, a preparation method thereof, and an application thereof in the electrochemical CN coupling synthesis of urea.
[0004] The technical solution adopted by the present invention is:
[0005] A carbon cloth-supported non-metallic covalent organic framework material catalyst electrode is a COF / MOF electrode of an enaminone structure porous organic framework material composite of MOF and COF supported on carbon cloth, which is synthesized with enaminone structure as a connecting unit and TDOEB, TAPT and NH2-MIL-125 (Ti) as raw materials.
[0006] The above-mentioned method for preparing a carbon cloth-supported non-metallic covalent organic framework material catalyst electrode comprises the following steps: loading TDOEB solid, TAPT solid and NH2-MIL-125 (Ti) solid into a pyrex tube, dissolving them in a mixed solvent, freezing and exhausting the air, and then flame-sealing the tube; then placing it in an oven for heating reaction, cooling the tube to room temperature, centrifuging and washing it with tetrahydrofuran, collecting yellow solids after vacuum drying, and fully grinding the solids to obtain catalyst powder; mixing the obtained catalyst powder with a membrane solution, 2-acetylene black, isopropanol, and ultrapure water to prepare ink, ultrasonicating, and using a pipette to drop the ink onto the carbon cloth to obtain a carbon cloth-supported COF / MOF composite electrode.
[0007] Furthermore, in the above-mentioned preparation method, the amount of TDOEB used is 0.03 mmol, the amount of TAPT used is 0.03 mmol, and the amount of NH2-MIL-125(Ti) used is 0.05 g, 0.1 g or 0.2 g.
[0008] Furthermore, in the above preparation method, the mixed solvent is: 1 mL of dioxane, 4 mL of mesitylene and 0.4 mL of 6M acetic acid solution.
[0009] Furthermore, in the above preparation method, the freezing is performed under 77K liquid nitrogen.
[0010] Furthermore, in the above-mentioned preparation method, the heating reaction temperature is 393K and the reaction time is 72h.
[0011] Furthermore, in the above preparation method, the amount of the catalyst powder is 3 mg, the amount of 2-acetylene black is 3 mg, the amount of membrane solution is 30 μL, the amount of isopropanol is 170 μL, and the amount of ultrapure water is 200 μL.
[0012] Furthermore, in the above preparation method, the ultrasonic time is 1 hour.
[0013] Furthermore, in the above-mentioned preparation method, the pretreatment method of the carbon cloth is: cut the carbon cloth into a rectangle of 1 cm×2 cm, soak it in acetone, anhydrous ethanol, concentrated nitric acid, anhydrous ethanol, and acetone in turn, ultrasonically oscillate for 30 minutes each time, and repeatedly wash it with ultrapure water, and vacuum dry the treated carbon cloth for use.
[0014] The above-mentioned carbon cloth-loaded non-metallic covalent organic framework material catalyst electrode is used in the electrochemical synthesis of urea.
[0015] Furthermore, for the above application, the method is as follows: the carbon cloth-loaded COF / MOF composite electrode is used as the working electrode, the counter electrode is a platinum sheet electrode, the reference electrode is an Ag / AgCl electrode, the cathode electrolyte is 35 mL of 0.1M KNO3 solution and 0.1M KHCO3 solution, respectively, and the anode electrolyte is 70 mL of 0.1M KHCO3 solution. At a potential of -0.3 to -0.7 V vs. RHE, CO2 is introduced into the cathode electrolyte, electrolyzed for 2 hours, and the cathode electrolyte product is collected.
[0016] The beneficial effects of the present invention are:
[0017] 1. The present invention utilizes a solvent thermal strategy to synthesize catalyst powder and prepare it into ink, uses carbon cloth to support the catalyst, the raw materials are simple and easy to obtain, and the synthesis operation is easy.
[0018] 2. The catalyst synthesized by the present invention is used for electrochemical synthesis of urea, achieving a Faraday efficiency of 20.04% and a urea yield of 1.579 μmol / mg / h at -0.5 V vs. RHE, showing good electrocatalytic activity and stability. The COF / MOF composite catalyst obtained by the present invention has good application prospects in the field of electrocatalytic urea synthesis. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is a SEM image of the COF / MOF-10 catalyst prepared in Example 1.
[0020] Figure 2 This is the FT-IR spectrum of the COF / MOF-10 catalyst prepared in Example 1.
[0021] Figure 3 is the XRD spectrum of the COF / MOF-10 catalyst prepared in Example 1.
[0022] Figure 4 This is the XPS graph of Ti 2p of the COF / MOF-10 catalyst prepared in Example 1.
[0023] Figure 5 This is a diagram of the experimental setup for electrochemical synthesis of urea using carbon cloth-loaded COF / MOF composite electrodes in Example 2.
[0024] Figure 6 This is a comparison chart of the LSV curves of the carbon cloth-loaded COF / MOF composite electrode in Ar and CO2 gases in Example 2.
[0025] Figure 7 It is the UV-vis urea standard curve of the diacetyl monooxime method for testing urea in Example 2.
[0026] Figure 8This is the urea Faraday efficiency diagram of the carbon cloth-loaded COF / MOF composite electrode in Example 2.
[0027] Fig. 9 This is a graph showing the urea yield of the carbon cloth-loaded COF / MOF composite electrode in Example 2. DETAILED DESCRIPTION
[0028] Example 1 Preparation of carbon cloth-supported COF / MOF composite electrode
[0029] (I) The preparation method is as follows:
[0030] 1) Pretreatment of carbon cloth: Cut the carbon cloth into a rectangle of 1 cm × 2 cm, soak it in acetone, anhydrous ethanol, concentrated nitric acid, anhydrous ethanol, and acetone in turn, ultrasonically vibrate it for 30 min each time, and wash it repeatedly with ultrapure water. Vacuum dry the treated carbon cloth for later use.
[0031] 2) Preparation of COF / MOF composite material: Powdered TDOEB 0.03mmol, TAPT 0.03mmol and 0.1g NH2-MIL-125(Ti) were ground together and transferred to a pyrex tube, and then 1mL of dioxane, 4mL of mesitylene, and 0.4mL of 6M acetic acid solution were added as a catalyst. After freezing at 77K (liquid nitrogen) and evacuating the air, the tube was flame-sealed. Then, the reaction was heated at 393K in an oven for 3 days, the tube was cooled to room temperature, centrifuged and washed several times with tetrahydrofuran (THF), and the yellow solid was collected after vacuum drying. The solid was fully ground to obtain the catalyst powder COF / MOF-10.
[0032] 3) Preparation of carbon cloth-supported catalyst electrode: 3 mg of catalyst powder, 3 mg of 2-acetylene black, 30 μL of DuPont membrane solution, 170 μL of isopropanol, and 200 μL of ultrapure water were mixed to prepare catalyst ink, and the ink was dispersed evenly by ultrasonication for 60 min. The ink was dripped onto the pretreated carbon cloth using a pipette, with the amount of dripping being 10-12 drops, and weighed after drying. The catalyst loading was calculated based on the mass of the carbon cloth before and after the dripping.
[0033] In addition, according to the above preparation method, only the amount of NH2-MIL-125(Ti) was adjusted to 0.05 g and 0.2 g, respectively, to prepare catalyst powders COF / MOF-5 and COF / MOF-20, respectively.
[0034] (II) Test results
[0035] Figure 1 is a SEM image of the COF / MOF-10 catalyst powder prepared in Example 1. Figure 1It can be seen that the material is a three-dimensional network structure composed of a variety of micropores growing around a square structure. Figure 2 is the FT-IR spectrum of the COF / MOF-10 catalyst powder prepared in Example 1. Figure 2 It can be seen that COF / MOF-10 has an additional Ti-O-Ti stretching (700 cm -1 ), proving that NH2-MIL-125(Ti) and EN-COF were successfully composited and the reaction proceeded according to the experimental design. Figure 3 This is the XRD spectrum of the COF / MOF-10 catalyst powder prepared in Example 1. Compared with the spectra of the raw materials EN-COF and NH2-MIL-125(Ti), in the comparison between the newly synthesized COF / MOF-10 catalyst powder and the raw materials, the characteristic peak of EN-COF at a small angle of 3.5° disappears, and the peak of NH2-MIL-125(Ti) also disappears, proving the formation of the new substance COF / MOF-10. Figure 4 is the XPS graph of Ti 2p of COF / MOF-10 catalyst in Example 1. It can be seen from the figure that the catalyst material exhibits two characteristic peaks at 458.5eV and 464.3eV, which are respectively attributed to Ti 4+ 2p 3 / 2 and Ti 4+ 2p 1 / 2 , proving that NH2-MIL-125(Ti) and EN-COF were successfully composited and the existence form of Ti did not change.
[0036] Example 2 Application of carbon cloth-supported COF / MOF composite electrode in electrocatalytic synthesis of urea
[0037] Test method: The prepared carbon cloth loaded COF / MOF composite electrode was used as the working electrode.
[0038] Experimental setup Figure 5 As shown, the experimental electrolyzer is an H-type electrolytic cell of Tianjin Aida, the proton exchange membrane is a Nafion117 membrane, the carbon cloth-loaded COF / MOF composite electrode prepared in Example 1 is placed on the cathode electrode clip as the working electrode, the reference electrode uses an Ag / AgCl electrode, the counter electrode uses a platinum sheet electrode, the cathode electrolyte is 35mL 0.1M KNO3 solution and 35mL0.1M KHCO3 solution, and the anolyte is 70mL0.1M KHCO3 solution. The experimental potential is set to -0.3~-0.7Vvs.RHE, Ar or CO2 is introduced into the cathode electrolyte, the electrolysis time is 2h, and the diacetyl monooxime method is used to detect the urea concentration in the cathode electrolyte.
[0039] The LSV curves of carbon cloth-supported COF / MOF-10 composite electrode in Ar and CO2 atmospheres are shown in Figure 2. Figure 6 As shown in the figure, the current density in the Ar atmosphere is higher than that in the CO2 atmosphere, that is, a strong hydrogen evolution side reaction occurs in the Ar atmosphere, while the hydrogen evolution reaction is weakened in the CO2 atmosphere, which is beneficial to CO2 and NO3 - Reduction reaction and further CN coupling to synthesize urea.
[0040] The standard curve of urea test and the urea Faraday efficiency and yield are as follows Figure 7 , Figure 8 , Fig. 9 As shown: The five standard curve concentration ranges of the experimental setting are 0, 0.5, 1.0, 2.0, and 2.5 μg mL -1 , the R of the standard curve was experimentally measured 2 It reaches 0.99906, with high credibility, and can be used as an external standard curve. Figure 8 To determine the Faradaic efficiency results, the catalyst electrode achieved a maximum Faradaic efficiency of 20.04% at -0.5 V vs. RHE. Fig. 9 To determine the urea production results, the catalyst electrode achieved a maximum urea production of 1.579 μmol / mg / h at -0.5 V vs. RHE.
[0041] In summary, the carbon cloth-loaded COF / MOF composite electrode of the present invention has high Faradaic efficiency and urea yield, and at the same time has good electrocatalytic stability. Therefore, this carbon cloth-loaded COF / MOF composite electrode has a relatively ideal development prospect in the field of electrocatalytic urea synthesis.
Claims
1. A carbon cloth-supported non-metallic covalent organic framework material catalyst electrode, characterized in that: The electrode is a COF / MOF electrode of an enaminone structure porous organic framework material composited with MOF and COF supported by carbon cloth, which is synthesized with enaminone structure as a connecting unit and TDOEB, TAPT and NH2-MIL-125 (Ti) as raw materials.
2. The method for preparing a carbon cloth-supported non-metallic covalent organic framework catalyst electrode according to claim 1, characterized in that: The method comprises the following steps: loading TDOEB solid, TAPT solid and NH2-MIL-125 (Ti) solid into a pyrex tube, dissolving the solids in a mixed solvent, freezing and exhausting the air, and then flame-sealing the tube; then placing the tube in an oven for heating and reaction, cooling the tube to room temperature, centrifuging and washing with tetrahydrofuran, vacuum drying and collecting yellow solids, and fully grinding the solids to obtain catalyst powders; mixing the obtained catalyst powders with a membrane solution, 2-acetylene black, isopropanol and ultrapure water to prepare ink, ultrasonicating, and using a pipette to drop the ink onto a carbon cloth to obtain a carbon cloth-loaded COF / MOF composite electrode.
3. The preparation method according to claim 2, characterized in that: The amount of TDOEB used is 0.03 mmol, the amount of TAPT used is 0.03 mmol, and the amount of NH2-MIL-125(Ti) used is 0.05 g, 0.1 g or 0.2 g.
4. The preparation method according to claim 2, characterized in that: The mixed solvent is: 1 mL of dioxane, 4 mL of mesitylene and 0.4 mL of 6M acetic acid solution.
5. The preparation method according to claim 2, characterized in that: The freezing is performed under 77K liquid nitrogen.
6. The preparation method according to claim 2, characterized in that: The heating reaction temperature is 393K and the reaction time is 72h.
7. The preparation method according to claim 2, characterized in that: The amount of the catalyst powder used was 3 mg, the amount of 2-acetylene black used was 3 mg, the amount of the membrane solution used was 30 μL, the amount of isopropanol used was 170 μL, and the amount of ultrapure water used was 200 μL; the ultrasonic time was 1 hour.
8. The preparation method according to claim 2, characterized in that: The carbon cloth pretreatment method is as follows: the carbon cloth is cut into a rectangle of 1 cm×2 cm, and is soaked in acetone, anhydrous ethanol, concentrated nitric acid, anhydrous ethanol, and acetone in sequence, each time undergoing ultrasonic oscillation for 30 minutes, and is repeatedly washed with ultrapure water, and the treated carbon cloth is vacuum dried for later use.
9. Use of the carbon cloth-supported non-metallic covalent organic framework material catalyst electrode according to claim 1 in electrochemical synthesis of urea.
10. The use according to claim 9, characterized in that: The method is as follows: the carbon cloth-loaded COF / MOF composite electrode is used as the working electrode, the counter electrode is a platinum electrode, the reference electrode is an Ag / AgCl electrode, the cathode electrolyte is 35 mL each of 0.1M KNO3 solution and 0.1M KHCO3 solution, and the anode electrolyte is 70 mL of 0.1M KHCO3 solution. At a potential of -0.3 to -0.7 V vs. RHE, CO2 is introduced into the cathode electrolyte, electrolyzed for 2 hours, and the cathode electrolyte product is collected.