A copper nanosheet catalyst with adjustable nanocavity content, a preparation method and applications thereof
By forming a nanocavity structure on the surface of copper nanosheets, the selectivity and stability issues of carbon dioxide reduction to ethylene were solved, and a highly efficient carbon dioxide reduction to ethylene process was achieved.
Patent Information
- Application Number
- CN202510186570.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-20
- Publication Date
- 2025-11-07
- Estimated Expiration
- 2045-02-20
AI Technical Summary
Existing technologies are not effective at promoting the reduction of carbon dioxide to ethylene, and there are competing reactions for the generation of other hydrocarbon products and hydrogen, resulting in low catalytic selectivity.
A copper nanosheet catalyst with adjustable nanocavity content was used. A nanocavity structure was formed on the surface of the copper nanosheet by UV light cleaning, which improved the local microenvironment, promoted CC coupling and CO enrichment, and improved the selectivity of carbon dioxide reduction to ethylene.
It significantly improves the selectivity and stability of carbon dioxide reduction to ethylene, and has significantly higher current density and Faraday efficiency than traditional copper catalysts, exhibiting excellent catalytic activity and long-term stability.
Smart Images
Figure CN119776874B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of metal catalysts, in particular to a copper nanosheet catalyst with adjustable nanocavity content, a preparation method and application. BACKGROUND
[0002] The extensive use of fossil fuels has disrupted the balance of the carbon cycle, leading to a sharp increase in the concentration of carbon dioxide in the atmosphere, which has made the greenhouse effect a pressing global problem. How to convert CO2 into value-added products has attracted the interest of researchers. However, CO2 is chemically inert, and it is very challenging to activate CO2 under conventional environmental conditions. Electrocatalytic carbon dioxide reduction reaction (CO2RR) is one of the methods for CO2 conversion, and is an attractive approach that provides a variety of reduced products from multiple proton-coupled electron transfer pathways, ranging from C1 (HCOOH, CO), C2 (CH3COOH, C2H4, C2H5OH), C3 (CH3COCH3, C3H7OH), etc. In particular, the electroreduction of carbon dioxide can establish a new carbon cycle path and establish a sustainable carbon economy, while the electricity in the electroreduction of carbon dioxide can be provided by electricity generated from renewable energy sources.
[0003] Compared with other products, the reduction of CO2 to ethylene is more popular because it has greater market demand and has a high value among all reduced products. For example, ethylene is a basic chemical raw material for the polymer industry, pharmaceuticals, and the synthesis of high-tech materials. In addition, ethylene can be directly used as a welding fuel or a natural gas additive. Currently, ethylene is mainly manufactured by cracking non-renewable oil at high temperatures. The production process is energy-consuming and polluting, which has a negative impact on the environment. On the contrary, CO2RR is a green and sustainable way to selectively produce ethylene. The key challenge of the current electrocatalytic reduction of CO2 to ethylene is to promote C-C bond coupling while reducing the competition of other carbon-hydrogen products and hydrogen generation.
[0004] Copper-based catalysts have been shown to have the ability to electroreduce CO2 to ethylene, and the reaction product selectivity of CO2RR depends largely on the surface properties and local environment of the catalyst. At the same time, slight changes in the catalyst-electrolyte interface can significantly affect the catalytic selectivity of the catalyst. Therefore, the development of a new catalyst with abundant catalytic interface and low coordination copper is considered an ideal method to improve the adsorption and desorption of ethylene intermediates, in which a metal copper catalyst with abundant defects can maximize the active sites, optimize the energy barrier of CO dimerization and improve the local pH value of the catalyst, which is crucial for the selective production of ethylene. SUMMARY
[0005] To solve the technical problems proposed in the background art, the present application develops a preparation method of copper nanosheet catalyst with adjustable nanocavity content, and the related materials can be applied to the direction of electrocatalytic reduction of carbon dioxide to produce ethylene. The catalyst obtained by the synthesis method can enrich CO produced in the carbon dioxide reduction process in the nanocavity, promoting C-C coupling. The nanocavity structure not only helps to improve the microenvironment around the catalyst, providing an ideal place for carbon dioxide adsorption and reduction, but also improves the selectivity of CO2 reduction to ethylene, providing a new idea for efficient conversion of carbon dioxide.
[0006] The present application adopts the following technical scheme: a preparation method of copper nanosheet catalyst with adjustable nanocavity content, characterized in that it comprises the following steps:
[0007] Step 1: weigh 0.05-0.1 g of copper nitrate trihydrate, 0.1-0.2 g of L-ascorbic acid, and place them in a beaker, add 20-30.0 mL of deionized water to dissolve, then add 0.1-0.2 g of polyvinylpyrrolidone (PVP) and 0.1-0.2 g of hexamethylenetetramine, stir for 30-60 minutes, and oil bath at 80℃ for 3h; after the end, collect the red product, wash it with ethanol and water several times, and place it in a vacuum drying oven at 60℃ for drying for 12h to obtain copper nanosheets;
[0008] Step 2: place the collected 40mg of copper nanosheets in an evaporating dish, place the evaporating dish in a UV light cleaning machine, set the power of the UV lamp tube to 200-300W in an ozone atmosphere, set the time to 30-120min, then turn over the obtained catalyst, repeat the above operation, and obtain the copper nanosheet catalyst with adjustable nanocavity content;
[0009] Preferably, in the case of a mass ratio of copper nitrate trihydrate to PVP of 1:(1-2), increasing the amount of the two can achieve large-scale synthesis.
[0010] Preferably, the temperature at which the PVP is dissolved in water is 30-60℃, and the stirring time is 0.5-1h.
[0011] Preferably, the distance between the catalyst and the UV lamp tube is 20mm.
[0012] Preferably, the power of the UV lamp tube is 300W, and the cleaning time is 30-120min.
[0013] The present application proposes a copper nanosheet catalyst with adjustable nanocavity content, which is prepared by the above method.
[0014] The present application also proposes the application of the copper nanosheet catalyst with adjustable nanocavity content, which is applied to the electrocatalytic reduction of carbon dioxide.
[0015] And the specific application method comprises the following steps:
[0016] 5mg of the above-mentioned copper nanosheet catalyst with adjustable nanocavity content is weighed and dispersed in 300mL of a mixed solution containing anhydrous ethanol: deionized water: Nafion in a volume ratio of 1.5:0.45:0.05, and ultrasonic dispersion is performed for 30min to obtain a uniform slurry;
[0017] 3uL of the slurry is dropped on a glassy carbon electrode with a diameter of 0.3cm, and after natural drying, the glassy carbon electrode is used as a working electrode, an Ag / AgCl electrode is used as a reference electrode, and a 1x1cm2 platinum sheet electrode is used as a counter electrode to form a three-electrode system for reduction operation;
[0018] The present application carries out electrocatalytic dioxygen reduction test in 0.6M K2CO3+0.4M KHCO3 electrolyte.
[0019] In the test, linear sweep voltammetry (LSV) is used to explore the electrocatalytic activity of the catalyst, and the current change with time at a fixed potential is tested by constant potential method (i-t) to carry out the reaction, and 0.2mL of gas above the electrolytic cell is injected into a gas chromatograph during the reaction. The performance of the catalyst prepared in the present application is compared with that of the precursor Cu nanosheet.
[0020] The catalyst prepared in step 3 is used as a working electrode, an Ag / AgCl electrode is used as a reference electrode, and a 1x1cm2 platinum sheet electrode is used as a counter electrode to form a three-electrode system, and under 0.6MK2CO3+0.4M KHCO3 electrolyte, a constant potential of-0.82V (vs.RHE) is used, the electrolyte is kept at 30mL and constantly circulated, the current change with time and the gas above the electrolytic cell is injected into a gas chromatograph every 2 hours to determine the faraday efficiency of ethylene in a period of time to judge the stability of the catalyst
[0021] In the test, linear sweep voltammetry (LSV) is used to explore the electrocatalytic activity of the catalyst, and the current change with time at a fixed potential is tested by constant potential method (i-t) to carry out the reaction, and 0.2mL of gas above the electrolytic cell is injected into a gas chromatograph during the reaction.
[0022] In a specific application, the pretreatment of the glassy carbon electrode: polish the surface of the glassy carbon electrode with 0.05 μm alumina polishing powder. Place the treated glassy carbon electrode in an aqueous solution containing 1.0 mM K3Fe(CN)6 and 0.1 M KCl, and observe the cyclic voltammogram (CV). If the anodic and cathodic peaks are symmetrical, have the same peak current value (IPC / IPA = 1), and the peak potential difference is about 60 mV, the electrode surface is considered to be well processed, otherwise it needs to be polished to meet the requirements.
[0023] The application prepares a copper nanosheet catalyst with adjustable nanocavity content and applies it to electrocatalytic reduction of carbon dioxide to produce ethylene. The electrode prepared in this way is tested by linear sweep voltammetry in the voltage range of 0 to -1.02 V vs RHE, and electrochemical performance is tested in the voltage range of -0.52 to -1.02 V vs RHE. When the overpotential is about -0.82 V vs RHE, the faradic efficiency of ethylene is about 73%.
[0024] Compared with the prior art, the application has the beneficial effects that:
[0025] The application adopts the method of UV light cleaning to synthesize a copper nanosheet catalyst with adjustable nanocavity content. The method is simple and efficient, has a short preparation time, and can be synthesized in large quantities.
[0026] The application uses the method of UV light cleaning to form nanocavities on the copper nanosheet by controlling the power and time of the UV lamp tube to adjust the intensity of the ultraviolet light emitted by the UV lamp tube. These nanocavities can improve the local microenvironment and be used to enrich *CO produced in the CO2RR catalytic process, promote C-C coupling, and improve the performance of carbon dioxide reduction to ethylene.
[0027] The copper nanosheet catalyst with adjustable nanocavity content prepared by the application exhibits excellent CO2RR catalytic activity and selectivity in 0.6 M K2CO3+0.4 M KHCO3 electrolyte, and the current density and faradic efficiency of ethylene are significantly higher than those of Cu catalyst. The catalyst can maintain a current density of -77 mA cm -2 for 58 hours in 0.6 M K2CO3+0.4 M KHCO3 electrolyte. This catalyst with high electrolysis selectivity and good stability has high practical application value. BRIEF DESCRIPTION OF DRAWINGS
[0028] Figure 1 The X-ray diffraction (XRD) pattern, Raman (Raman) pattern and X-ray photoelectron spectroscopy (XPS) pattern of the copper nanosheet catalyst with adjustable nanocavity content prepared by the application are shown in the following figure.
[0029] Figure 2is a scanning electron microscope (SEM) image of a copper nanosheet catalyst with tunable nanocavity content prepared by the present application. As shown in the figure, smooth and flat copper nanosheets were synthesized before UV light cleaning, and many nanocavities appeared on the copper nanosheets after UV light cleaning.
[0030] Figure 3 is a N2 adsorption-desorption isotherm (BET) and size distribution curve of a copper nanosheet catalyst with tunable nanocavity content prepared by the present application.
[0031] Figure 4 is a linear sweep voltammetry (LSV) curve of a copper nanosheet catalyst with rich nanocavities (UV-60min) and a copper nanosheet catalyst in a 0.6M K2CO3+0.4M KHCO3 electrolyte filled with saturated carbon dioxide, a Faraday efficiency diagram of electrocatalytic carbon dioxide reduction to ethylene at different potentials, and a product distribution diagram on a gas chromatograph.
[0032] Figure 5 is a long-term stability diagram of a copper nanosheet catalyst with rich nanocavities (UV-60min) prepared by the present application in a 0.6M K2CO3+0.4M KHCO3 electrolyte at a potential of-0.82V (vs. RHE).
[0033] In the figure, the horizontal axis of the obtained XRD diagram is the diffraction angle (2θ), and the vertical axis is the diffraction peak intensity (Intensity); the horizontal axis of the XPS diagram is the binding energy (Binging Energy), and the vertical axis is the binding energy intensity (Intensity); the horizontal axis of the BET diagram is the relative pressure (P / P0), and the vertical axis is the pore volume (cm 3 g -1 ); the horizontal axis of the linear sweep voltammetry (LSV) diagram is the applied voltage (E (V vs RHE)), and the vertical axis is the current density (Current density); the horizontal axis of the obtained carbon dioxide reduction product Faraday efficiency diagram is the applied voltage (E (V vs RHE)), and the vertical axis is the carbon dioxide reduction product Faraday efficiency (FE); the horizontal axis of the gas chromatogram is the peak time (time), and the vertical axis is the peak intensity (Intensity). DETAILED DESCRIPTION
[0034] Hereinafter, the present application will be further described in conjunction with the accompanying drawings and specific embodiments, and it should be noted that the following described embodiments or technical features can be combined in any manner to form new embodiments without conflict.
[0035] The chemical reagents used in the present application are all analytical pure copper nitrate trihydrate, L-ascorbic acid, hexamethylenetetramine, PVP, deionized water, and the UV light cleaning machine used in step 2 is BZS250GF-TC.
[0036] Example 1:
[0037] 0.05 g of copper nitrate trihydrate and 0.1 g of L-ascorbic acid were weighed into a 50 mL glass reaction bottle, 20 mL of deionized water was added, and stirred uniformly. Then, 0.1 g of PVP and 0.1 g of hexamethylenetetramine were added, and stirred for 0.5 h to obtain a light yellow solution. Then, the solution was placed in an 80°C oil bath for 3 h. After the end, the red product was collected and washed several times, and was placed in a 60°C vacuum drying oven for drying for 12 h to prepare the precursor Cu nanosheet.
[0038] 40 mg of the precursor obtained in the above step was placed in an evaporation dish. First, the equipment drawer was opened, the height of the workpiece platform from the UV lamp tube was adjusted, the evaporation dish was placed in the UV light cleaning machine, the power switch on the left side of the control panel was turned on, and the fan started to operate. The UV lamp tube was turned on according to the switch button on the right side of the operation panel. After a certain time of irradiation, the irradiated object was taken out after waiting for 1-2 min, the material inside was turned over, and the above operation was repeated.
[0039] The catalyst prepared in Example 1 was applied to the electrolytic reduction reaction.
[0040] Test Example 1:
[0041] First, 5 mg of the catalyst was dispersed in 300 mL of a mixed solution containing anhydrous ethanol: deionized water: Nafion in a volume ratio of 1.5:0.45:0.05, and was ultrasonically dispersed into an ink. Then 3 uL of the ink was uniformly coated on a glassy carbon electrode with a diameter of 0.3 cm for use. In addition, 0.6 M K2CO3+0.4 M KHCO3 electrolyte was used for performance test, and before the test, high-purity carbon dioxide was continuously charged into the electrolyte to exclude oxygen dissolved in the electrolyte. The test conditions: linear sweep voltammetry (LSV) test range is 0- -1.02 V vs RHE, and the scanning speed is 0.05 V / s.
[0042] After 1 h of testing at different voltages, the sampling needle took 0.2 mL of gas above the electrolytic cell after the CO2RR reaction, and injected into the gas chromatograph. After the injection was completed, the CO2RR products were sequentially peaked on the detector of the gas chromatograph, and the Faraday efficiency of the corresponding carbon dioxide reduction products was calculated using the fitted standard curve.
[0043] Test Example 2:
[0044] Stability is one of the most important properties of catalysts. The copper nanosheet catalyst with rich nanocavity obtained by Example 1 (UV-60min) was subjected to constant potential test. Figure 5 The current-time curve of a copper nanosheet catalyst with rich nanocavity at -0.82V (vs. RHE) for 58 hours of cyclic electrolysis test can be seen that the current and FE do not decrease significantly, further indicating that the copper nanosheet catalyst with nanocavity structure (UV-60min) has excellent cyclic stability.
[0045] Result analysis:
[0046] As shown in the attached Figure 1 X-ray diffractometer was used for phase analysis of the catalyst, and the obtained diffraction peaks only exist in the (111), (200) and (220) crystal faces of copper single element, and the diffraction peaks are sharp and the crystallinity is good, and there is no appearance of other impurity characteristic peaks on Raman, according to the X-ray photoelectron spectroscopy, the synthesized copper nanosheet only appears Cu 2p peak, and there is no satellite peak of Cu 2+ , and the Auger electron spectrum of X-ray photoelectron spectroscopy appears a peak at 569.0eV, indicating that Cu in the sample is mainly Cu 0 , these results show that pure phase copper nanosheet can be synthesized by UV irradiation, and no other impurity phase is introduced.
[0047] As shown in the attached Figure 2 scanning electron microscope (SEM), the surface of the synthesized precursor Cu nanosheet is smooth and flat, while the surface of the Cu nanosheet after UV light cleaning is obviously rough, and many nanocavities appear on the surface, and the nanoscale structure size is still maintained, and no structure collapse occurs after UV light cleaning.
[0048] As shown in the attached Figure 3 According to the BET results, the specific surface area of the synthesized precursor Cu nanosheet is 2.27m 3 g -1 , and the size is mainly concentrated in the micropore region. After UV light cleaning, the specific surface area of UV-60min is 3.04m 3 g -1 , and the size distribution is mainly concentrated in the mesopore region (about 21nm).
[0049] Based on all the above characterization results, the copper nanosheet catalyst with adjustable nanocavity content can be prepared by the UV light cleaning method.
[0050] The specific method of the nanocavity-rich copper nanosheet catalyst (UV-60min) prepared by the application for electrocatalytic reduction of carbon dioxide to produce ethylene in 0.6M K2CO3+0.4MKHCO3 electrolyte is as follows: a standard three-electrode system, the counter electrode is a platinum sheet electrode, the reference electrode is Ag / AgCl; the electrode, and the electrolyte is a mixed solution of 0.6M K2CO3+0.4M KHCO3.
[0051] As shown in the LSV test results in the drawings, Figure 4 In the 0.6M K2CO3+0.4M KHCO3 electrolyte, the overpotential of the nanocavity-rich copper nanosheet catalyst (UV-60min) prepared by the application during electrolysis is significantly lower than that of the Cu nanosheet. The current density at the same potential is also larger than that of the Cu nanosheet. The CO2RR performance of the nanocavity-rich copper nanosheet catalyst (UV-60min) prepared in Example 1 and the Cu catalyst prepared in Comparative Example 1 is compared. As can be seen from the figure, the ethylene faradic efficiency of the nanocavity-rich copper nanosheet catalyst (UV-60min) at each potential is significantly higher than that of the Cu catalyst, indicating that the nanocavity structure can effectively improve the catalytic performance of the CO2RR to produce ethylene. At-0.82V(vs.RHE), the FE(C2H4) of the copper nanosheet catalyst with a nanocavity structure reaches 73%, and the peak area of ethylene and carbon monoxide of the nanocavity-rich copper nanosheet catalyst (UV-60min) is significantly higher than that of the Cu catalyst on the gas chromatograph.
[0052] As shown in the drawings, Figure 5 Under the conditions of 0.6M K2CO3+0.4M KHCO3 electrolyte and-0.82V(vs.RHE), the nanocavity-rich copper nanosheet catalyst (UV-60min) prepared by the application can maintain a current density of-77mA cm -2 and a faradic efficiency of ethylene of more than 65% for 58 hours, further indicating that the nanocavity-rich copper nanosheet catalyst (UV-60min) has excellent stability.
[0053] The above electrochemical test results show that the nanocavity-rich copper nanosheet catalyst (UV-60min) is well applied to long-time electrolysis of carbon dioxide reduction to produce ethylene, and has higher catalytic activity and stability than the copper nanosheet, and has high practical application value.
[0054] The above embodiments are only preferred embodiments of the application, and cannot be used to limit the scope of protection of the application. Any non-essential changes and substitutions made by those skilled in the art on the basis of the application all belong to the scope of protection claimed by the application.
Claims
1. A method for preparing a copper nanosheet catalyst with adjustable nanocavity content, characterized in that, Comprising the following steps: Step 1, take 0.05 ~ 0.1 g of copper nitrate trihydrate, 0.1 ~ 0.2 g of L-ascorbic acid, put it in a beaker, add 20 ~ 30.0 mL of deionized water to dissolve, then add 0.1 ~ 0.2 g of polyvinylpyrrolidone (PVP) and 0.1 ~ 0.2 g of hexamethylenetetramine, stir for 30 ~ 60 minutes, and oil bath at 80℃ for 3h; after the end, collect the red product, wash it with ethanol and water for several times, and dry it in a vacuum drying oven at 60℃ for 12h to obtain copper nanosheets; Step 2, put the 40 mg of copper nanosheets collected into an evaporating dish, place the evaporating dish in a UV light cleaning machine, set the power of the UV lamp tube to 200 ~ 300 W in an ozone atmosphere, set the time to 30 ~ 120 min, then turn over the operation, repeat the above operation, and obtain copper nanosheet catalyst with adjustable nanocavity content.
2. The method for preparing a copper nanosheet catalyst with adjustable nanocavity content according to claim 1, characterized in that, The mass ratio of copper nitrate trihydrate to PVP is 1:(1 ~ 2), and the use amount of the two is increased, which can realize large-scale synthesis.
3. The method of claim 1, wherein the copper nanosheet catalyst with tunable nanocavity content is prepared by the following steps: (1) preparing a copper nanosheet catalyst precursor; (2) adding a reducing agent to the copper nanosheet catalyst precursor to obtain a copper nanosheet catalyst with tunable nanocavity content. The distance between the copper nanosheet and the UV lamp tube is 20 mm.
4. The method of claim 1, wherein the copper nanosheet catalyst with tunable nanocavity content is prepared by the following steps: (1) preparing a copper nanosheet catalyst precursor; (2) adding a reducing agent to the copper nanosheet catalyst precursor to obtain a copper nanosheet catalyst with tunable nanocavity content. The power of the UV lamp tube is 300 W, and the cleaning time is 30 ~ 120 min.
5. A copper nanosheet catalyst with tunable nanocavity content, characterized in that, The method is prepared by any one of claims 1-4.
6. Use of the nanocavity-tunable copper nanosheet catalyst according to claim 5, characterized in that, For electrocatalytic reduction of carbon dioxide.
7. The method of claim 6, wherein the composition is applied to the skin of the user at least once a day. Comprising the following steps: Take 5 mg of the above copper nanosheet catalyst with adjustable nanocavity content, disperse it in 300 mL of mixed solution containing anhydrous ethanol: deionized water: Nafion with a volume ratio of 1.5 : 0.45 : 0.05, and ultrasonic dispersion for 30 min to obtain a uniform slurry. Take 3 uL slurry drop on the glassy carbon electrode with diameter of 0.3 cm, and after natural drying, the glassy carbon electrode is used as the working electrode, and the Ag / AgCl electrode is used as the reference electrode, and the 1 x 1 cm 2 Pt sheet electrode is used as the counter electrode to form a three-electrode system for electrolytic reduction.
Citation Information
Patent Citations
Preparation method of fluoride-free super-hydrophobic photocatalytic ultraviolet-proof textile
CN111021049A