Preparation method and application of COF-Cu / Cu2O nanocluster composite material
By preparing COF-Cu/Cu2O nanocluster composites, the problem of instability in the activity and selectivity of CO2 electrocatalysts in extreme environments is solved, and efficient and stable CO2 reduction effect is achieved.
Patent Information
- Application Number
- CN202510410208.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-02
- Publication Date
- 2025-07-04
AI Technical Summary
The existing CO2 electrocatalytic reducing agents have problems such as poor conductivity, prone to agglomeration of active sites, and unstable catalytic performance, especially in extreme environments, which are difficult to maintain high activity and selectivity.
Covalent organic frame material was used to composite the inorganic metal, and COF nanosheets were prepared by microwave-ultrasonic combination solvothermal method, and Cu/Cu2O nanoclusters were deposited on their surface by electrochemical deposition to form COF-Cu/Cu2O nanocluster composite material.
It has achieved high electrochemical activity, high product selectivity and good stability of CO2 reduction catalysts, which can maintain catalytic performance under different environments, and has high yields and good catalytic site dispersion.
Smart Images
Figure CN120250025A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of electrocatalysis, and relates to a composite catalyst material, a preparation method thereof and an application, in particular to a preparation method of a COF-Cu / Cu2O nanocluster composite material and its application in the field of electrochemical catalysis for CO2 reduction. Background Art
[0002] Since the Industrial Revolution, with the increasingly severe climate change, global warming and various ecological problems caused by the excessive anthropogenic emission of CO2. How to achieve the total control of CO2 gas and realize the resource recovery and reuse of CO2 has become a hot topic of concern and research in recent years. In recent years, researchers have developed a variety of methods for CO2 conversion. Currently, the most mainstream methods include electrocatalytic reduction of CO2, photocatalytic reduction of CO2, biochemical reduction of CO2, and thermal catalytic reduction of CO2. Among them, the electrocatalytic reduction method of CO2 has gradually entered the mainstream view due to its strong universality, relatively low requirements for the external environment, high yield and controllable conditions.
[0003] Currently, the main research directions of electrocatalytic CO2 reduction focus on two aspects: electrocatalytic reduction equipment and process, and electrocatalytic reducing agent materials. For electrocatalytic reducing agents of CO2, high activity, high selectivity and stability are the key conditions for excellent electrocatalytic reducing agents. COFs (covalent organic framework materials) are widely used in the fields of catalysis, gas adsorption, energy storage and conversion due to their porosity, high specific surface area, adjustable structure and excellent stability. However, the conductivity of pure COFs non-metal catalysts is relatively poor, which restricts their electrochemical activity. Metal catalysts have strong electrochemical activity, but are easily affected by changes in the external environment, and it is difficult to maintain stable catalytic performance. Moreover, metal materials, especially inorganic metal materials at the nanoscale, are prone to agglomeration under the reduction current, resulting in a reduction in active sites and affecting catalytic activity. Summary of the Invention
[0004] Aiming at the problems existing in the prior art, the present invention aims to provide an organic framework / inorganic metal composite material with high electrochemical activity, high product selectivity and high stability in a complex environment; it is proposed to use a covalent organic framework / inorganic metal composite material as an electrocatalyst for CO2 reduction. Using a covalent organic framework material as a carrier, the rich pore structure and heteroatom distribution are conducive to the confined deposition of inorganic metal materials, exposing more catalytic active sites. The catalyst combines the high electrochemical activity and high selectivity of inorganic metal materials. At the same time, the covalent organic framework material itself has excellent stability, ensuring that the catalyst can operate stably in various relatively extreme environments (different pH, temperature, voltage).
[0005] Another object of the present invention is to provide a method for preparing a COFs nanosheet / metal nanocluster composite structure COF-Cu / Cu2O NC composite material; another object of the present invention is to provide a use of a COFs nanosheet / metal cluster composite structure COF-Cu / Cu2O NC composite material.
[0006] The COFs nanosheet / metal cluster composite structure COF-Cu / Cu2O NC described in the present invention has 2D COF nanosheets rich in nitrogen and oxygen heteroatoms as a base material, providing abundant deposition sites for Cu / Cu2O nanoclusters, and the size of the metal clusters is 1-5nm.
[0007] The preparation method of the COF-Cu / Cu2O nanocluster composite material comprises the following steps:
[0008] (1) Preparation of TP-COF by microwave-ultrasound combined solvothermal method:
[0009] First, 2,3,6,7,10,11-hexamidotriphenylene hexahydrochloride and p-benzoquinone are placed in a microwave ultrasonic reaction bottle, then dry dimethylformamide DMF is added and ultrasonically mixed, then formic acid solution is added and ultrasonically mixed, the reaction container containing the sample is transferred to a microwave-ultrasonic reactor, the reaction mixture is heated under a microwave environment under an inert gas atmosphere, the reaction products are washed and separated with ultrapure water and methanol, respectively, and the obtained precipitate is vacuum dried to obtain a TP-COF powder sample;
[0010] The dried TP-COF powder sample was ultrasonically exfoliated in a methanol solution, filtered with an ultra-fine pore filter membrane and vacuum dried to obtain 2D COF nanosheets;
[0011] (2) Cu / Cu2O nanoclusters are deposited on the COF surface by electrochemical deposition:
[0012] First, the 2D COF nanosheets obtained in step (1) were added to a mixed solvent of ethanol and isopropanol, and a 5 wt.% nafion solution was added. The mixed solution was fully ultrasonically mixed and then coated on the surface of conductive carbon paper. Then, the carbon paper was used as a working electrode, the graphite rod electrode was used as a counter electrode, the Ag / AgCl electrode was used as a reference electrode, and the prepared Cu 2+ The solution was used as an electrodeposition solution to carry out electrodeposition in a three-electrode system single-chamber electrolytic cell to obtain a COF-Cu / Cu2O NC composite material;
[0013] (3) Post-processing of composite materials samples:
[0014] After the electrodeposition in step (2) is completed, the working electrode is rinsed and dried, and then the dried sample is transferred to a vacuum container for storage.
[0015] In step (1), the dosage ratio of 2,3,6,7,10,11-hexamminetriphenylene hexahydrochloride, p-benzoquinone, dimethylformamide DMF and formic acid solution is 0.16 mmol: 0.48 mmol: 10 mL: 2 mL; among them, the concentration of the formic acid solution is 5 M;
[0016] The inert gas is high-purity nitrogen; the reaction temperature is set at 120 - 150 °C; the microwave power is set at 100 - 400 w; the reaction time is 4 - 8 h; the ultrasonic time is set at 1 - 3 s with an interval of 1 s;
[0017] The number of washing times is 3 - 5 times with ultrapure water and 3 - 5 times with methanol; the separation method is centrifugation or suction filtration, and the suction filtration membrane is a 0.22 μm organic system nafion membrane;
[0018] The ultrasonic exfoliation selects methanol as the solvent and uses a high-performance ultrasonic crusher for ultrasonic treatment for 3 - 5 h.
[0019] The temperature of the vacuum drying is 60 - 80 °C and the time is 12 - 24 h.
[0020] In step (2), in the ethanol and isopropanol mixed solvent, the concentration of 2D COF nanosheets is 0.5 - 1 mg / mL; and, in the ethanol and isopropanol mixed solvent, the volume ratio of ethanol to isopropanol is 1:1 - 3:1;
[0021] The volume ratio of 5 wt.% nafion solution to the ethanol and isopropanol mixed solvent is 1:10 - 1:20;
[0022] The ultrasonic time of the prepared mixed solution is 1 - 2 h;
[0023] The conductive carbon paper selects highly hydrophobic GDL carbon paper, which is dried at 60 - 80 °C for 6 - 12 h before use; the sample coating amount is 0.3 - 0.5 mg / cm 2 ; after coating, the carbon paper is naturally dried at room temperature;
[0024] In the electroplating solution Cu 2+ solution, it contains 0.1 - 0.5 M of CuSO4, 0.1 - 0.2 M of H2SO4 and 10 - 20 mM of 3,5-diamino-1,2,4-triazole DAT; the solvent is a mixed solution of ultrapure water and ethanol, and the volume ratio of ultrapure water to ethanol is 3:1 - 1:1;
[0025] The instrument for the electrodeposition method uses an automatic laboratory electrochemical workstation (Shanghai, CHI760e) for current control; before electrodeposition, the carbon paper coated with the sample is immersed in the electrodeposition solution for 1 h; the electrodeposition method uses the I-T chronoamperometry method or the C-V cyclic voltammetry method;
[0026] Among them, for the chronoamperometry method, the voltage is set to -0.2 V and the time is set to 10 - 30 min;
[0027] Among them, for the cyclic voltammetry method, the voltage is set to -0.3 V - 0.6 V, the scanning rate is 0.1 V / s, and the time is 60 - 120 min.
[0028] In step (3), the rinsing is successively carried out with ultrapure water and ethanol; the drying is carried out by nitrogen flushing.
[0029] The COF-Cu / Cu2O NC composite material is applied to the electrochemical catalytic reduction of CO2.
[0030] The present invention prepares a COF-Cu / Cu2O NC catalyst material with a composite structure of an organic framework nanosheet material and Cu2O nanoclusters through a wet chemical method. This composite material is used for the electrochemical catalytic conversion of CO2 and exhibits high catalytic performance and stability.
[0031] Compared with the prior art, the present invention has the following remarkable advantages:
[0032] (1) The preparation method is simple, highly feasible, and economical;
[0033] (2) This composite material has the advantages of high yield, high product selectivity, high crystallinity, good stability, high dispersion of catalytic sites, high CO2 adsorption, significant promotion of charge transfer, and promotion of gas mass transfer;
[0034] (3) The COF-Cu / Cu2O NC composite catalytic material has a stable framework structure, which is conducive to maintaining the material stability in different environments. The dispersed metal sites are conducive to charge transfer, and it shows strong catalytic performance in the electrochemical catalytic conversion of CO2; Description of the Drawings
[0035] Figure 1 It is the scanning electron microscope (SEM) images of the materials of Comparative Example 1, Comparative Example 2, and Example 2;
[0036] Figure 2 It is the transmission electron microscope (TEM) images of Comparative Example 1 and Example 2;
[0037] Figure 3 It is the high-resolution transmission electron microscope (HRTEM) image of Example 2 and its lattice analysis;
[0038] Figure 4 It is the X-ray photoelectron spectroscopy (XPS) diagram of Example 2;
[0039] Figure 5 It is the bar graph of the Faraday efficiency of the products of Comparative Example 1, Comparative Example 2, Example 1, Example 2, and Example 3, and the line graph of the partial current density of the dominant product CH4 at different potentials in Example 2. Specific Embodiments
[0040] The technical solution of the present invention will be further described below with reference to the accompanying drawings.
[0041] Example 1
[0042] A COF-Cu / Cu2O NC composite catalytic material with a composite structure of an organic framework nanosheet material and Cu2O nanoclusters is prepared as follows:
[0043] (1) Prepare TP-COF by microwave-ultrasonic combined solvothermal method:
[0044] First, take 86 mg of 2,3,6,7,10,11-hexamminetriphenylene hexahydrochloride and 25.6 mg of p-benzoquinone and place them in a special microwave-ultrasonic reaction flask. Add 10 ml of dry DMF and mix evenly by ultrasonic treatment. Then add 2 ml of 5M formic acid solution and mix evenly by ultrasonic treatment. Transfer the reaction vessel containing the sample to a microwave-ultrasonic reactor. Under a N2 gas atmosphere, heat the reaction mixture to the boiling point in a microwave environment. The reaction temperature is set at 150 °C, the reaction time is 8 h, the microwave power is set at 400 W, and the ultrasonic time is set at 3 s with an interval of 1 s. Subsequently, wash the reaction product with ultrapure water and methanol respectively and separate it by suction filtration using an organic microporous filter membrane. Dry the obtained precipitate in a vacuum environment to obtain a dark red TP-COF powder sample. Place 50 mg of the dried powder sample in 200 ml of methanol solution and perform ultrasonic peeling for 5 h using an ultrasonic crusher. Then separate it by suction filtration using an ultra-fine microporous filter membrane and dry it in a vacuum environment for 12 h to obtain 2D COF nanosheets.
[0045] (2) Deposit Cu / Cu2O nanoclusters on the COF surface by electrochemical deposition method:
[0046] Take 10 mg of the 2D COF nanosheet sample obtained in step (1) and add it to a 1:1 mixed solvent of 10 ml of ethanol and isopropanol. Add 0.5 ml of 5 wt.% nafion solution. After fully ultrasonicating the mixed solution, coat it on the surface of a hydrophobic conductive carbon paper. The COF sample loading is 0.3 - 0.5 mg / cm 2 .
[0047] The conductive carbon paper loaded with the COF sample was used as the working electrode, the graphite rod electrode as the counter electrode, and the Ag / AgCl electrode as the reference electrode. The prepared 0.1 M CuSO4 / 0.1 M H2SO4 / 10 mM DAT (3,5-diamino-1,2,4-triazole) solution was used as the electrodeposition solution, and the solvent of the electrodeposition solution was a mixed solution of ethanol and water with a ratio of 1:2. The carbon paper coated with the sample was immersed in the electrodeposition solution for 1 h and then subjected to electrochemical deposition. The electrodeposition reaction was carried out in a three-electrode system single-chamber electrolytic cell; the electrodeposition instrument used an automatic laboratory electrochemical workstation (Shanghai, CHI760e) for current control; the electrodeposition method used the I-T chronoamperometry method, the voltage of the chronoamperometry method was set to -0.2 V, and the time was set to 10 min.
[0048] (3) Post-treatment of the composite material sample:
[0049] The working electrode obtained in step (2) was rinsed with ultrapure water and ethanol respectively, and dried by nitrogen flushing. The dried sample was transferred to a vacuum container for storage.
[0050] Example 2
[0051] Compared with Example 1, the difference lies in that the time of electrochemical deposition in step (2) was set to 20 min.
[0052] Example 3
[0053] Compared with Example 1, the difference lies in that the time of electrochemical deposition in step (2) was set to 30 min.
[0054] Example 4
[0055] Compared with Example 1, the difference lies in that the electrochemical deposition method in step (2) was selected as cyclic voltammetry, and the time was set to 60 min.
[0056] Example 5
[0057] Compared with Example 1, the difference lies in that the electrochemical deposition method in step (2) was selected as cyclic voltammetry, and the time was set to 120 min.
[0058] Comparative Example 1
[0059] The hydrophobic conductive carbon paper coated only with 2D COF nanosheets was used as Comparative Example 1.
[0060] Comparative Example 2
[0061] Compared with Example 1, the hydrophobic conductive carbon paper without coating 2D COF nanosheets was selected, and Cu / Cu2O was directly electrochemically deposited.
[0062] Application Example:
[0063] Electrochemical CO2 catalytic conversion:
[0064] The electrochemical performance test of CO2 RR was measured using a three-electrode flow electrolytic cell. The diaphragms of the anode and cathode chambers were pretreated faa-130 anion exchange membranes. The target implementation sample was selected as the working electrode, the flattened nickel foam as the counter electrode, 1M KOH solution as the electrolyte, and the Hg / HgO electrode (filled with 1M KOH) as the reference electrode. All the potentials stated in this study were converted to the reversible hydrogen electrode to evaluate the electrochemical catalytic performance. The following formula (Nernst equation, 25 °C) was used to convert all the measured potentials to RHE:
[0065] E(vs RHE) = E(vs Hg / HgO) + 0.2046V + 0.059*PH - 0.0296*log(P CO2 / P0)
[0066] The electrochemical performance of the samples was tested using an automatic laboratory electrochemical workstation (Shanghai, CHI760e). The CO2 gas flow rate was controlled at 30 sccm using a mass flow controller. The flow rates of the cathode and anode electrolytes were controlled at 6 ml / min respectively using a peristaltic pump (MF3540 timed and quantitative titration pump). The gas products were analyzed online using an on-line gas chromatograph (GC), a flame ionization detector, and a thermal conductivity detector. The calculation method of the Faraday efficiency of the gas products is as follows:
[0067]
[0068] F: Faraday constant, F = 96485 C / mol
[0069] X g : Concentration of the target product, ppm
[0070] V CO2 : CO2 flow rate at the outlet of the electrolytic cell, mL / min
[0071] K: Number of electrons transferred corresponding to different products
[0072] i total : Total current during the reaction
[0073] V m : Molar volume of the gas, V at normal temperature and pressure m = 24.5 L / mol
[0074] The liquid products were detected by 1H NMR spectroscopy using the DMSO internal standard method. The calculation method of the Faraday efficiency of the liquid products is as follows:
[0075]
[0076] F: Faraday constant, F = 96485 C / mol
[0077] C: Concentration of the target product, mol / L
[0078] V liquid : Volume of the electrolyte, L
[0079] K: Number of electrons transferred corresponding to different products
[0080] i total : Total current during the reaction
[0081] t: Reaction time, min
[0082] Experimental results:
[0083] Figure 1 Scanning electron microscopy shows that in Comparative Example 1, the lamellar stacked 2D COF lamellar structure is closely adhered. Comparative Example 2 shows a large aggregation of metal atoms on the surface of the conductive carbon paper during direct electrochemical deposition, forming large metal particles. Example 2 shows that after electrochemical deposition on the surface of the 2D COF material, no obvious aggregation of metal particles is observed on the 2D COF surface. The rich pore structure and rich heteroatom distribution sites are conducive to the confined deposition of inorganic metals, effectively restricting the aggregation of metal atoms.
[0084] Figure 2 It shows that in Comparative Example 1, the exfoliated 2D COF nanosheets have an ultrathin nanosheet structure. Example 2 is the metal nanoclusters confinedly deposited on the surface of the 2D COF nanosheets, with a diameter of 1 - 5 nm.
[0085] Figure 3 It shows the surface lattice analysis of Example 2. The high-resolution electron microscopy image clearly shows the lattice fringes of the 2D COF material, and at the same time shows the clear lattice fringes of the tiny Cu / Cu2O nanoclusters doped therein. The cluster size is about 1 - 5 nm.
[0086] Figure 4 It shows the elemental composition and chemical state of Example 2, in which the Cu element exists in both +1 and 0 valence states.
[0087] Figure 5 It shows that different valuable products are obtained for different samples in the electrochemical catalytic environment. Among them, Figure b shows that Example 2 has the highest selectivity for the CH4 product, and Figure f shows that it has the highest CH4 partial current density at a potential of -1.376 V relative to the reversible hydrogen electrode.
Claims
1. A preparation method of a COF-Cu / Cu2O nanocluster composite material, characterized in that, The steps are as follows: (1) Prepare TP-COF by microwave-ultrasound combined solvothermal method: First, load 2,3,6,7,10,11-hexamminetriphenylene hexahydrochloride and p-benzoquinone into a microwave-ultrasound reaction flask. Then, add dry dimethylformamide (DMF) and mix evenly by ultrasound. Subsequently, add formic acid solution and mix evenly by ultrasound. Transfer the reaction vessel containing the sample to a microwave-ultrasound reactor, and heat the reaction mixture under microwave environment in an inert gas atmosphere. Wash and separate the reaction product with ultrapure water and methanol respectively, and vacuum dry the obtained precipitate to obtain a TP-COF powder sample; Ultrasonically exfoliate the dried TP-COF powder sample in methanol solution, filter it with an ultra-fine microporous filter membrane and vacuum dry it to obtain 2D COF nanosheets; (2) Deposit Cu / Cu2O nanoclusters on the COF surface by electrochemical deposition method: First, the 2D COF nanosheets obtained in step (1) were added to a mixed solvent of ethanol and isopropanol, and a 5 wt.% nafion solution was added. The mixed solution was fully ultrasonically mixed and then coated on the surface of conductive carbon paper. Then, the carbon paper was used as a working electrode, the graphite rod electrode was used as a counter electrode, the Ag / AgCl electrode was used as a reference electrode, and the prepared Cu 2+ The solution was used as an electrodeposition solution to carry out electrodeposition in a three-electrode system single-chamber electrolytic cell to obtain a COF-Cu / Cu2O NC composite material; (3) Post-treatment of the composite material sample: Rinse and dry the working electrode after the electro-deposition in step (2), and then transfer the dried sample to a vacuum container for storage.
2. The preparation method of the COF-Cu / Cu2O nanocluster composite material according to claim 1, characterized in that, In step (1), the dosage ratio of 2,3,6,7,10,11-hexamminetriphenylene hexahydrochloride, p-benzoquinone, dimethylformamide (DMF) and formic acid solution is 0.16 mmol: 0.48 mmol: 10 mL: 2 mL; among them, the concentration of the formic acid solution is 5 M.
3. The preparation method of the COF-Cu / Cu2O nanocluster composite material according to claim 1, characterized in that, In step (1), the inert gas is high-purity nitrogen; the reaction temperature is set at 120-150 °C; the microwave power is set at 100-400 w; the reaction time is 4-8 h; the ultrasonic time is set at 1-3 s with an interval of 1 s.
4. The preparation method of the COF-Cu / Cu2O nanocluster composite material according to claim 1, characterized in that, In step (1), the number of washing times is 3-5 times with ultrapure water and 3-5 times with methanol; the separation method is centrifugation or filtration, and the filtration membrane for filtration is a 0.22 μm organic nafion membrane; The ultrasonic exfoliation selects methanol as the solvent and uses a high-performance ultrasonic crusher for ultrasonic treatment for 3-5 h; The temperature of the vacuum drying is 60-80 °C and the time is 12-24 h.
5. The preparation method of the COF-Cu / Cu2O nanocluster composite material according to claim 1, characterized in that, In step (2), in the ethanol and isopropanol mixed solvent, the concentration of 2D COF nanosheets is 0.5-1 mg / mL; and in the ethanol and isopropanol mixed solvent, the volume ratio of ethanol to isopropanol is 1:1-3:1; The volume ratio of 5 wt.% nafion solution to the ethanol and isopropanol mixed solvent is 1:10~1:20; The ultrasonic time of the configured mixed solution is 1-2 h; The conductive carbon paper selected is a highly hydrophobic GDL carbon paper, which is dried at 60 - 80 °C for 6 - 12 h before use; the sample coating amount is 0.3 - 0.5 mg / cm 2 ; after coating, the carbon paper is naturally dried at room temperature.
6. The preparation method of the COF-Cu / Cu2O nanocluster composite material according to claim 1, characterized in that, In step (2), the electroplating solution Cu 2+ solution contains 0.1 - 0.5 M of CuSO4, 0.1 - 0.2 M of H2SO4, and 10 - 20 mM of 3,5-diamino-1,2,4-triazole DAT; the solvent is a mixed solution of ultrapure water and ethanol, and the volume ratio of ultrapure water to ethanol is 3:1 - 1:1; Soak the carbon paper coated with the sample in the electro-deposition solution for 1 h before electro-deposition; The electro-deposition method adopts I-T chronoamperometry or C-V cyclic voltammetry.
7. The preparation method of the COF-Cu / Cu2O nanocluster composite material according to claim 6, characterized in that, When adopting chronoamperometry, the voltage is set at -0.2 V and the time is set at 10-30 min; when adopting cyclic voltammetry, the voltage is set at -0.3 V-0.6 V, the scanning rate is 0.1 V / s, and the time is 60-120 min.
8. The preparation method of the COF-Cu / Cu2O nanocluster composite material according to claim 1, characterized in that, In step (3), the rinsing is successively carried out with ultrapure water and ethanol; the drying adopts the method of nitrogen rinsing.
9. A COF-Cu / Cu2O nanocluster composite material, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 8, using 2D COF nanosheets with nitrogen and oxygen heteroatoms as the substrate material, and depositing Cu / Cu2O nanoclusters on the surface, with the size of the metal clusters being 1-5 nm.
10. Use of the COF-Cu / Cu2O nanocluster composite material according to claim 9 for electrocatalytic CO2 reduction.