A carbon cloth loaded non-metallic covalent organic framework material catalyst electrode, a preparation method and application thereof
By using an organic framework material catalyst with a carbon cloth-supported MOF and COF composite enamine ketone structure, the problems of insufficient activity and selectivity of electrocatalysts were solved, achieving efficient electrochemical synthesis of urea and simplifying the preparation process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-19
- Publication Date
- 2026-03-20
AI Technical Summary
Existing electrocatalysts have insufficient catalytic activity and selectivity in the electrochemical synthesis of urea, and their preparation process is complex, making it difficult to achieve efficient and stable CN-coupling reactions.
A non-metallic covalent organic framework catalyst with a carbon cloth-supported MOF and COF composite enamine ketone structure was synthesized into catalyst powder via a solvothermal method and formulated into ink, which was then loaded onto carbon cloth for electrochemical synthesis of urea.
A urea yield of 20.04% Faraday efficiency and 1.579 μmol/mg/h was achieved at -0.5V vs. RHE, demonstrating good electrocatalytic activity and stability, and simplifying the preparation process.
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of electrocatalysis, and particularly relates to a carbon cloth loaded nonmetallic covalent organic framework material catalyst electrode and a preparation method thereof and application thereof in electrochemical synthesis of urea. BACKGROUND
[0002] Compared with the traditional Haber-Bosch method, the electrochemical synthesis of urea technology exhibits significant environmental and economic benefits. This technology can be carried out at lower temperature and pressure, reducing energy consumption and equipment cost, 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 sources such as solar or wind energy, further promoting environmental sustainability. In addition, the process produces fewer by-products, simplifying waste treatment processes and reducing costs. The process flow of electrochemical synthesis of urea is flexible, and the output can be adjusted according to demand, suitable for small-scale or distributed production. The development of this technology also promotes technological innovation in related fields of the chemical industry, such as electrocatalyst materials, opening up new paths for sustainable development. The key to achieving efficient urea production lies in the development of electrocatalysts with high catalytic activity, good selectivity, and long service life. In recent years, a new method of electrocatalytic C-N coupling synthesis of urea using nitrogen-containing waste and carbon dioxide has received widespread attention. This method has obvious advantages such as low energy consumption, simple operation, and environmental protection. The enaminone structure synthesized by the application of MOF and COF composite is a new composite functional material, which has attracted widespread attention in the field of electrochemical synthesis of urea. SUMMARY
[0003] The purpose of the present application is to provide a carbon cloth loaded MOF and COF composite enaminone structure organic framework material COF / MOF electrode with simple raw materials, convenient synthesis, stable performance and good selectivity, and a preparation method thereof and its application in electrochemical C-N coupling synthesis of urea.
[0004] The technical scheme adopted by the present application is:
[0005] A carbon cloth loaded nonmetallic covalent organic framework material catalyst electrode is a carbon cloth loaded MOF and COF composite enaminone structure porous organic framework material COF / MOF electrode synthesized by using enaminone structure as a connecting unit and TDOEB, TAPT and NH2-MIL-125(Ti) as raw materials.
[0006] The preparation method of the carbon cloth loaded nonmetallic 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 in a mixed solvent, freezing and evacuating air, then flame sealing the tube; then placing it in an oven for heating reaction, cooling the tube to room temperature, centrifugal separation and washing with tetrahydrofuran, and collecting yellow solid after vacuum drying, and grinding the solid to obtain catalyst powder; mixing the obtained catalyst powder with film solution, 2-alkyne black, isopropyl alcohol and ultrapure water to prepare ink, ultrasonicating, and using a pipette to drop the ink on the carbon cloth to obtain a carbon cloth loaded COF / MOF composite electrode.
[0007] Further, in the preparation method, the amount of TDOEB is 0.03 mmol, the amount of TAPT is 0.03 mmol, and the amount of NH2-MIL-125(Ti) is 0.05 g, 0.1 g or 0.2 g.
[0008] Further, in the preparation method, the mixed solvent is 1 mL of dioxane, 4 mL of mesitylene and 0.4 mL of 6M acetic acid solution.
[0009] Further, in the preparation method, the freezing is performed at 77K liquid nitrogen.
[0010] Further, in the preparation method, the heating reaction temperature is 393K, and the reaction time is 72h.
[0011] Further, in the preparation method, the amount of catalyst powder is 3 mg, the amount of 2-alkyne black is 3 mg, the amount of film solution is 30 μL, the amount of isopropyl alcohol is 170 μL, and the amount of ultrapure water is 200 μL.
[0012] Further, in the preparation method, the ultrasonicating time is 1h.
[0013] Further, in the preparation method, the pretreatment method of the carbon cloth is as follows: cutting the carbon cloth into a rectangle with a size of 1cm×2cm, sequentially immersing in acetone, anhydrous ethanol, concentrated nitric acid, anhydrous ethanol, acetone, ultrasonicating for 30 min each time, and repeatedly washing with ultrapure water, and vacuum drying the treated carbon cloth for standby.
[0014] The application of the carbon cloth loaded nonmetallic covalent organic framework material catalyst electrode in electrochemical synthesis of urea.
[0015] Further, the application is as follows: the carbon cloth loaded COF / MOF composite electrode is used as a working electrode, a platinum sheet electrode is used as a counter electrode, an Ag / AgCl electrode is used as a reference electrode, 0.1M KNO3 solution and 0.1M KHCO3 solution are used as cathode electrolyte, each 35mL, 0.1M KHCO3 solution is used as anode electrolyte, 70mL, CO2 is introduced into the cathode electrolyte under-0.3~ -0.7V vs.RHE potential, electrolysis is carried out for 2h, and the cathode electrolyte product is collected.
[0016] The application has the following beneficial effects:
[0017] 1. The application synthesizes catalyst powder by using a solvothermal strategy and prepares ink, uses carbon cloth to load the catalyst, and raw materials are simple and easy to obtain, and synthesis operation is low in difficulty.
[0018] 2. The catalyst synthesized by the application is used for electrochemical synthesis of urea, reaches 20.04% of Faraday efficiency and 1.579umol / mg / h of urea yield under-0.5V vs.RHE, and exhibits good electrocatalytic activity and stability, and the COF / MOF composite catalyst obtained by the application has good application prospect in the field of electrocatalytic urea synthesis. BRIEF DESCRIPTION OF DRAWINGS
[0019] Figure 1 Fig. 1 is a SEM diagram of the COF / MOF-10 catalyst prepared in Example 1.
[0020] Figure 2 Fig. 3 is an FT-IR spectrum diagram of the COF / MOF-10 catalyst prepared in Example 1.
[0021] Figure 3 Fig. 4 is an XRD spectrum diagram of the COF / MOF-10 catalyst prepared in Example 1.
[0022] Figure 4 Fig. 5 is an XPS diagram of Ti 2p of the COF / MOF-10 catalyst prepared in Example 1.
[0023] Figure 5 Fig. 6 is an experimental device diagram of electrochemical synthesis of urea by using the carbon cloth loaded COF / MOF composite electrode in Example 2.
[0024] Figure 6 Fig. 7 is a comparison diagram of LSV curves of the carbon cloth loaded COF / MOF composite electrode in Ar and CO2 gas in Example 2.
[0025] Figure 7 Fig. 8 is a UV-vis urea standard curve for testing urea by using a diacetyl monoxime method in Example 2.
[0026] Figure 8is the urea faradic efficiency plot of the carbon cloth loaded COF / MOF composite electrode in Example 2.
[0027] Figure 9 is the urea yield plot of the carbon cloth loaded COF / MOF composite electrode in Example 2. DETAILED DESCRIPTION
[0028] Preparation of carbon cloth loaded COF / MOF composite electrode in Example 1
[0029] (I) Preparation method is as follows:
[0030] 1) Pretreatment of carbon cloth: cut the carbon cloth into 1 cm x 2 cm size rectangle, sequentially immerse in acetone, anhydrous ethanol, concentrated nitric acid, anhydrous ethanol, acetone, each time ultrasonic oscillation for 30 min, and repeatedly wash with ultrapure water, vacuum dry the treated carbon cloth for standby.
[0031] 2) Preparation of COF / MOF composite material: grind the powdered TDOEB 0.03 mmol, TAPT 0.03 mmol and 0.1 g of NH2-MIL-125(Ti) together and transfer to a pyrex tube, then add 1 mL of dioxane, 4 mL of mesitylene, and add 0.4 mL of 6M acetic acid solution as catalyst, freeze at 77K (liquid nitrogen) and evacuate air, then flame seal the tube. Then heat the reaction in an oven at 393K for 3 days, cool the tube to room temperature, centrifuge and wash several times with tetrahydrofuran (THF), and collect the yellow solid after vacuum drying, grind the solid thoroughly to obtain catalyst powder COF / MOF-10.
[0032] 3) Preparation of carbon cloth loaded catalyst electrode: mix 3 mg of catalyst powder, 3 mg of 2-alkyne black, 30 μL of Dupont film solution, 170 μL of isopropyl alcohol, 200 μL of ultrapure water to make catalyst ink, ultrasonic oscillation for 60 min to disperse uniformly. Use a pipette to drop the ink on the pretreated carbon cloth, drop amount 10-12 drops, weigh after drying, calculate the catalyst loading according to the mass of carbon cloth before and after dropping.
[0033] In addition, according to the above preparation method, only the amount of NH2-MIL-125(Ti) is adjusted to 0.05 g and 0.2 g respectively, catalyst powders COF / MOF-5 and COF / MOF-20 are prepared respectively.
[0034] (II) Test results
[0035] Figure 1 is the SEM image of the COF / MOF-10 catalyst powder prepared in Example 1, from Figure 1It can be seen that the material is a three-dimensional network structure composed of various micropores growing around the block structure as the center. Figure 2 is the FT-IR spectrum of the COF / MOF-10 catalyst powder prepared in Example 1, which is compared with the spectra of the raw materials EN-COF and NH2-MIL-125(Ti). Figure 2 It can be seen that the COF / MOF-10 has Ti-O-Ti stretching (700 cm -1 ) in addition to EN-COF synthesized by TDOEB and TAPT alone, proving that NH2-MIL-125(Ti) and EN-COF are successfully compounded, and the reaction proceeds as designed. Figure 3 is the XRD spectrum of the COF / MOF-10 catalyst powder prepared in Example 1, which is compared with the spectra of the raw materials EN-COF and NH2-MIL-125(Ti). In the comparison of the new synthesized COF / MOF-10 catalyst powder with the raw materials, the characteristic peak value of EN-COF at a small angle of 3.5° disappears, and the peak value of NH2-MIL-125(Ti) also disappears, proving the generation of the new substance COF / MOF-10. Figure 4 is the XPS graph of Ti 2p of the COF / MOF-10 catalyst in Example 1. As can be seen from the graph, the catalyst material exhibits two characteristic peaks at 458.5 eV and 464.3 eV, 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 are successfully compounded, and the form of existence of Ti has not changed.
[0036] Application of carbon cloth loaded COF / MOF composite electrode in electrocatalytic synthesis of urea in Example 2
[0037] Test method: The prepared carbon cloth loaded COF / MOF composite electrode is used as the working electrode.
[0038] The experimental device is shown in Figure 5 , the experimental electrolytic cell is H-type electrolytic cell of Tianjin Aida, the proton exchange membrane is Nafion117 membrane, the carbon cloth loaded COF / MOF composite electrode prepared in Example 1 is placed on the cathode electrode clamp as the working electrode, the reference electrode uses Ag / AgCl electrode, and the counter electrode uses platinum sheet electrode. The cathode electrolyte is 35 mL of 0.1M KNO3 solution and 35 mL of 0.1M KHCO3 solution, and the anode electrolyte is 70 mL of 0.1M KHCO3 solution. The experimental potential is set to -0.3 to -0.7V vs. RHE, Ar or CO2 is introduced into the cathode electrolyte, the electrolysis time is 2h, and the diacetyl monoxime method is used to detect the urea concentration in the cathode electrolyte.
[0039] The LSV curves of the carbon cloth supported COF / MOF-10 composite electrode in Ar and CO2 atmospheres are shown in Figure 1. Figure 6 As shown in Figure 1, the current density in Ar atmosphere is higher than that in CO2 atmosphere, that is, a strong hydrogen evolution side reaction occurs in Ar atmosphere, and the hydrogen evolution reaction is weakened in CO2 atmosphere, which is beneficial to the reduction reaction of CO2 and NO3 - and further C-N coupling to synthesize urea.
[0040] The standard curve of urea test, urea Faraday efficiency and yield are shown in Figure 2. Figure 7 、 Figure 8 、 Figure 9 As shown in Figure 2, the five standard curve concentration ranges of the experimental setting are 0, 0.5, 1.0, 2.0 and 2.5 μg / mL -1 , respectively, and the R 2 of the standard curve measured in the experiment reaches 0.99906, which has high reliability and can be used as an external standard curve. Figure 8 To determine the Faraday efficiency, the catalyst electrode reaches a maximum Faraday efficiency of 20.04% at-0.5 V vs. RHE. Figure 9 To determine the urea yield, the catalyst electrode reaches a maximum urea yield of 1.579 μmol / mg / h at-0.5 V vs. RHE.
[0041] In summary, the carbon cloth supported COF / MOF composite electrode has high Faraday efficiency and urea yield, and has good electrocatalytic stability, so the carbon cloth supported COF / MOF composite electrode has a relatively ideal development prospect in the field of electrocatalytic urea synthesis.
Claims
1. A carbon cloth-supported nonmetallic covalent organic framework material catalyst electrode, characterized in that, The electrode is a COF / MOF electrode, a porous organic framework material composed of carbon cloth-supported MOF and COF, synthesized using enaminoketone structures as connecting units and TDOEB, TAPT, and NH2-MIL-125(Ti) as raw materials. The method for preparing a carbon cloth-supported non-metallic covalent organic framework material catalyst electrode includes the following steps: TDOEB solid, TAPT solid, and NH2-MIL-125(Ti) solid are loaded into a Pyrex tube, dissolved in a mixed solvent, frozen and the air is purged, and then the tube is flame-sealed; then placed in an oven and heated at 393 K for 72 h; the tube is cooled to room temperature, centrifuged, washed with tetrahydrofuran, vacuum dried, and the yellow solid is collected; the solid is thoroughly ground to obtain catalyst powder; the obtained catalyst powder is mixed with a membrane solution, 2-acetylenic black, isopropanol, and ultrapure water to prepare an ink; the mixture is sonicated, and the ink is dropped onto carbon cloth using a pipette to obtain a carbon cloth-supported COF / MOF composite electrode. The mixed solvent is: 1 mL dioxane, 4 mL mesitylene, and 0.4 mL 6 M acetic acid solution.
2. The carbon cloth-supported non-metallic covalent organic framework material catalyst electrode according to claim 1, characterized in that, The dosage of TDOEB is 0.03 mmol, the dosage of TAPT is 0.03 mmol, and the dosage of NH2-MIL-125(Ti) is 0.05 g, 0.1 g, or 0.2 g.
3. The carbon cloth-supported non-metallic covalent organic framework material catalyst electrode according to claim 1, characterized in that, The freezing was performed at 77 K in liquid nitrogen.
4. The carbon cloth-supported non-metallic covalent organic framework material catalyst electrode according to claim 1, characterized in that, The amount of catalyst powder used is 3 mg, the amount of 2-acetylene black used is 3 mg, the amount of membrane solution used is 30 μL, the amount of isopropanol used is 170 μL, and the amount of ultrapure water used is 200 μL; the ultrasonic time is 1 h.
5. A carbon cloth-supported non-metallic covalent organic framework catalyst electrode according to claim 1, characterized in that, The pretreatment method for the carbon cloth is as follows: cut the carbon cloth into rectangles of 1 cm × 2 cm, soak them in acetone, anhydrous ethanol, concentrated nitric acid, anhydrous ethanol and acetone in sequence, ultrasonically vibrate for 30 min each time, and wash them repeatedly with ultrapure water. The treated carbon cloth is then vacuum dried for later use.
6. The application of the carbon cloth supported nonmetallic covalent organic framework material catalyst electrode as described in claim 1 in the electrochemical synthesis of urea.
7. The application according to claim 6, characterized in that, The method is as follows: A carbon cloth-supported COF / MOF composite electrode is used as the working electrode, a platinum sheet electrode is used as the counter electrode, and an Ag / AgCl electrode is used as the reference electrode. The cathode electrolyte consists of 35 mL each of 0.1 M KNO3 solution and 0.1 M KHCO3 solution, and the anolyte consists of 70 mL of 0.1 M KHCO3 solution. CO2 is introduced into the cathode electrolyte at a potential of -0.3 to -0.7 V vs. RHE, and electrolysis is carried out for 2 h. The cathode electrolyte products are then collected.