CN114395769B - Supported copper catalyst and preparation method and application thereof - Google Patents

Supported copper catalyst and preparation method and application thereof Download PDF

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CN114395769B
CN114395769B CN202210111273.8A CN202210111273A CN114395769B CN 114395769 B CN114395769 B CN 114395769B CN 202210111273 A CN202210111273 A CN 202210111273A CN 114395769 B CN114395769 B CN 114395769B
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copper
cerium
catalyst
supported copper
methane
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CN114395769A (en
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熊宇杰
江亚文
李嘉威
龙冉
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University of Science and Technology of China USTC
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    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
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    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/055—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material
    • C25B11/057—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material consisting of a single element or compound
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
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    • C25B11/091—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds
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Abstract

The invention provides a supported copper catalyst, wherein the carrier of the supported copper catalyst is cerium oxide quantum dots, and the active substance is copper monoatoms. The invention provides a preparation method of a supported copper catalyst, which uses polyalcohol as a solvent, a stabilizer and a reducer, wherein cerium oxide quantum dots are synthesized by heating, a copper source is added after a reaction solution is cooled, and then the cerium oxide quantum dot supported copper monoatomic catalyst is obtained by heating. The preparation method of the supported copper catalyst provided by the invention is simple to operate and easy to amplify, and when the flow cell is used for carrying out the electrocatalytic carbon dioxide reduction reaction, the high methane selectivity and methane partial current density are obtained. The invention also provides application of the supported copper catalyst.

Description

Supported copper catalyst and preparation method and application thereof
Technical Field
The invention belongs to the technical field of electrocatalysis, and particularly relates to a supported copper catalyst, a preparation method and application thereof, in particular to a supported copper electrocatalyst, a preparation method thereof and a method for preparing methane by electrocatalytic reduction of carbon dioxide by using the supported copper electrocatalyst.
Background
Fossil energy is the main energy source for the development of the society and the production and living of human beings. Carbon dioxide is discharged into the atmosphere as a final product in the use process of fossil energy, and excessive carbon dioxide discharge can cause various environmental problems such as seawater acidification, greenhouse effect and the like, thereby bringing great threat to sustainable development of human society.
The use of electrocatalytic processes to convert carbon dioxide and water into valuable products such as carbon monoxide, methane, ethylene, etc. is considered a very promising way of carbon dioxide conversion. Carbon monoxide and formate can be prepared by two electron transfer reduction methods using various catalysts, and high selectivity (Faraday efficiency greater than 95%) and high current density (greater than 100 mA/cm) have been achieved 2 ) And long-term stability (greater than 100 h). Methane is a very valuable electro-reduction product of carbon dioxide and can be directly used in a very mature natural gas industrial system, but the carbon dioxide can be reduced to produce methane by obtaining 8 electrons, and the preparation of methane with high selectivity and high current density is still a challenge at present.
Disclosure of Invention
In view of the above, the present invention aims to provide a supported copper catalyst, a preparation method and an application thereof, wherein the supported copper catalyst provided by the present invention exhibits high methane selectivity and current density of methane part in electrocatalytic carbon dioxide reduction.
The invention provides a supported copper catalyst, comprising:
the carrier is cerium oxide quantum dots;
an active material, the active material being a copper atom.
Preferably, the molar ratio of copper to cerium in the supported copper catalyst is (1-20): 100.
preferably, the size of the cerium oxide quantum dot is 1-10 nm.
Preferably, the copper atoms are distributed in a monoatomic state on the surface of the cerium oxide quantum dot.
The invention provides a preparation method of the supported copper catalyst, which comprises the following steps:
and mixing the copper source and the cerium source solution and then reacting to obtain the supported copper catalyst.
Preferably, the copper source is selected from one or more of copper nitrate trihydrate, copper acetate, copper sulfate and copper acetylacetonate.
Preferably, the preparation method of the cerium source solution includes:
and mixing the cerium source with a solvent for reaction to obtain a cerium source solution.
Preferably, the cerium source is selected from one or more of cerium nitrate hexahydrate, cerium acetate and cerium acetylacetonate;
the solvent is selected from polyols.
Preferably, the temperature of the mixing is 60-120 ℃;
the temperature of the reaction is 160-220 ℃.
The invention provides an application of the supported copper catalyst in preparing methane.
The copper-based catalyst is the most widely studied electrocatalyst for synthesizing more than two electron transfer reduction products at present, but in the invention, the mechanism of the electrocatalytic carbon dioxide reduction reaction is complex, and the method involves multiple steps and multiple products such as C-O bond fracture, C-H bond and C-C bond generationThe generation path of the substances is also in competition of hydrogen evolution side reaction, so that reasonable design of the copper-based catalyst is key for high-activity and high-selectivity electrocatalytic conversion of methane. The invention synthesizes cerium oxide (CeO) by using polyalcohol as solvent, stabilizer and reducer and adopting a two-step heating method 2 ) According to the quantum dot supported copper single-atom catalyst, cerium oxide quantum dot catalysts with different copper loadings can be prepared by adjusting the addition amount of a copper source.
The invention provides a supported copper catalyst, which comprises a cerium oxide quantum dot carrier and a copper monoatomic active site. The catalyst provided by the invention uses low-cost polyol as a solvent, a stabilizer and a reducing agent, and the cerium oxide quantum dot supported copper catalyst is obtained through a simple two-step heating method. The preparation method of the catalyst provided by the invention has the advantages of low raw material cost, simple operation and easy amplification.
In the catalyst provided by the invention, the carrier cerium oxide quantum dot is smaller than 10nm, has a large specific surface area, has a plurality of oxygen defects on the surface, can realize high load of copper on the surface of the cerium oxide quantum dot, and has single-atom state distribution on the surface of the cerium oxide quantum dot, and the copper active sites are isolated, so that the carbon-carbon coupling step is not easy to occur in the electrocatalytic carbon dioxide reduction process, and the generation of byproducts of ethylene, ethanol and propanol is reduced; the copper monoatomic active site also has stronger adsorption capacity to the carbon monoxide intermediate in the electrocatalytic carbon dioxide reduction process, so that the deep hydrogenation of the carbon monoxide intermediate is easy, and finally, the high methane product selectivity is shown; at 200mA/cm 2 ～600mA/cm 2 In constant current reaction, the methane Faraday efficiency can be over 60 percent, the highest methane Faraday efficiency can be 67 percent, and the highest methane partial current density is 364mA/cm 2 Exhibiting good potential for industrial application.
Drawings
FIG. 1 is an atomic-scale resolution transmission electron microscope image of a cerium oxide quantum dot-supported copper catalyst with a molar ratio of copper to cerium of 10% prepared in example 4 of the present invention;
FIG. 2 shows XRD diffraction patterns of cerium oxide quantum dot supported copper catalysts with different molar ratios of copper to cerium prepared in examples 1 to 4 of the present invention;
FIG. 3 is a synchrotron radiation characterization of cerium oxide quantum dot supported copper catalysts prepared in examples 1-4 of the present invention with different copper to cerium molar ratios;
FIG. 4 is a graph showing the Faraday efficiency of the electrocatalytic carbon dioxide reduction to methane for the preparation of cerium oxide quantum dot supported copper catalysts with different copper to cerium molar ratios prepared in examples 5-8 of the present invention;
FIG. 5 is a graph of partial current density for methane corresponding to electrocatalytic carbon dioxide reduction using a constant current method for cerium oxide quantum dot supported copper catalysts prepared in examples 5-8 of the present invention with different copper to cerium molar ratios.
Detailed Description
The following description of the technical solutions in the embodiments of the present invention will be clear and complete, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention provides a supported copper catalyst, comprising:
the carrier is cerium oxide quantum dots;
an active material, the active material being a copper atom.
In the present invention, the active substance is supported on a carrier.
In the present invention, the size of the cerium oxide quantum dot is preferably 1 to 10nm, more preferably 2 to 8nm, still more preferably 2 to 6nm, and most preferably 2 to 3nm.
In the present invention, the copper atoms are preferably copper monoatoms, and the copper atoms are preferably distributed in a monoatomic state on the surface of the cerium oxide quantum dot.
In the present invention, the molar ratio of copper to cerium in the supported copper catalyst is preferably (1 to 20): 100, more preferably (5 to 15): 100, still more preferably (8 to 12): 100, most preferably 10:100.
the invention provides a preparation method of the supported copper catalyst, which comprises the following steps:
and mixing the copper source and the cerium source solution and then reacting to obtain the supported copper catalyst.
In the present invention, the copper source is preferably selected from one or more of copper nitrate trihydrate, copper acetate, copper sulfate, and copper acetylacetonate.
In the present invention, the preparation method of the cerium source solution preferably includes:
and mixing the cerium source with a solvent for reaction to obtain a cerium source solution.
In the present invention, the cerium source is preferably selected from one or more of cerium nitrate hexahydrate, cerium acetate and cerium acetylacetonate.
In the present invention, the solvent is preferably selected from the group consisting of polyhydric alcohols, more preferably one or more selected from the group consisting of triethylene glycol, diethylene glycol and ethylene glycol.
In the present invention, the ratio of the cerium source and the solvent is preferably (100 to 2000) mg: (25-100) mL, more preferably (500-1500) mg: (30-90) mL, more preferably (800-1200) mg: (40-80) mL, most preferably 1000mg: (50-70) mL.
In the present invention, the mixing of the cerium source and the solvent is denoted as a first mixing, which is preferably performed under stirring; the temperature of the first mixing is preferably 60 to 120 ℃, more preferably 70 to 110 ℃, more preferably 80 to 100 ℃, most preferably 100 ℃; the time of the first mixing is preferably 10 to 60 minutes, more preferably 20 to 50 minutes, and most preferably 30 to 40 minutes.
In the present invention, the reaction performed after the first mixing is referred to as a first reaction, which is preferably performed under stirring; the temperature of the first reaction is preferably 160 to 220 ℃, more preferably 170 to 210 ℃, more preferably 180 to 200 ℃, and most preferably 180 ℃; the time of the first reaction is preferably 10 to 120 minutes, more preferably 30 to 100 minutes, still more preferably 50 to 80 minutes, and most preferably 60 to 70 minutes.
In the present invention, it is preferable to stop heating after the completion of the first reaction, and cool the obtained reaction solution to room temperature to obtain a cerium source solution.
In the present invention, the molar ratio of copper in the copper source and cerium in the cerium source solution is preferably (1 to 20): 100, more preferably (5 to 15): 100, still more preferably (8 to 12): 100, most preferably 10:100.
in the present invention, the mixing of the copper source and the cerium source solution is referred to as a second mixing; the second mixing is preferably carried out under stirring; the temperature of the second mixing is preferably 60 to 120 ℃, more preferably 70 to 110 ℃, more preferably 80 to 100 ℃, most preferably 100 ℃; the second mixing time is preferably 10 to 60 minutes, more preferably 20 to 50 minutes, and most preferably 30 to 40 minutes.
In the present invention, the second mixed reaction is referred to as a second reaction; the second reaction is preferably carried out under stirring; the temperature of the second reaction is preferably 160 to 220 ℃, more preferably 170 to 210 ℃, more preferably 180 to 200 ℃, and most preferably 180 ℃; the time of the second reaction is preferably 10 to 120 minutes, more preferably 30 to 100 minutes, still more preferably 50 to 80 minutes, and most preferably 60 to 70 minutes.
In the present invention, the second reaction preferably further comprises, after completion:
the heating was stopped, and the resulting reaction solution was cooled to room temperature.
In the present invention, the second reaction preferably further comprises, after completion:
and (3) precipitating, washing and drying the obtained reaction product to obtain the supported copper catalyst.
In the present invention, the reagent of the precipitant is preferably a mixed solvent, more preferably comprising: a strongly polar solvent and a weakly polar solvent.
In the present invention, the strong polar solvent is preferably selected from one or more of methanol, ethanol and isopropanol; the weak polar solvent is preferably selected from one or more of ethyl acetate, n-hexane and cyclohexane; the volume ratio of the strong polar solvent to the weak polar solvent is preferably (0.1-1): 1, more preferably (0.3 to 0.7): 1, more preferably (0.4 to 0.6): 1, most preferably 0.5:1.
the invention provides an application of the supported copper catalyst in preparing methane.
In the present invention, the method for producing methane is preferably electrocatalytic reduction of carbon dioxide to methane.
In the present invention, the method for producing methane more preferably comprises:
adopting a three-electrode chemical system, and preparing methane by electrocatalytic carbon dioxide reduction with constant current potential or constant current method;
the working electrode in the three-electrode chemical system is prepared from the supported copper catalyst in the technical scheme.
In the present invention, the working electrode is preferably assembled into an electrocatalytic carbon dioxide reduction flow cell during the preparation of methane by electrocatalytic carbon dioxide reduction.
In the present invention, the method for preparing the working electrode preferably includes:
coating the catalyst ink on the surface of the gas diffusion electrode, and drying to obtain a working electrode;
the catalyst ink contains the supported copper catalyst in the technical scheme.
In the present invention, the preparation method of the catalyst ink preferably includes:
and mixing the supported copper catalyst and the Nafion solution in the dispersion liquid to obtain the catalyst ink.
In the present invention, the mass concentration of the Nafion solution is preferably 0.1 to 10%, more preferably 0.5 to 8%, more preferably 1 to 6%, more preferably 2 to 5%, and most preferably 3 to 4%.
In the present invention, the dispersion is preferably selected from a low boiling point solvent, more preferably one or more selected from methanol, ethanol, propanol and isopropanol.
In the present invention, the volume ratio of the Nafion solution to the dispersion is preferably (0.001 to 1): 1, more preferably (0.005 to 0.8): 1, more preferably (0.01 to 0.6): 1, more preferably (0.05 to 0.4): 1, more preferably (0.1 to 0.3): 1, most preferably 0.2:1.
in the present invention, the concentration of the supported copper catalyst in the catalyst ink is preferably 1 to 10mg/mL, more preferably 2 to 8mg/mL, still more preferably 3 to 6mg/mL, and most preferably 4 to 5mg/mL.
In the present invention, the mixing method is preferably ultrasonic, so that the supported copper catalyst is uniformly dispersed.
In the present invention, the gas diffusion electrode is preferably selected from a carbon-based material gas diffusion electrode or a PTFE gas diffusion electrode.
In the present invention, the loading amount of the copper-supported catalyst in the catalyst ink on the gas diffusion electrode is preferably 0.05 to 5mg/cm 2 More preferably 0.1 to 3mg/cm 2 More preferably 0.5 to 2mg/cm 2 Most preferably 0.7mg/cm 2 。
In the present invention, the three-electrode electrochemical system preferably further comprises:
a reference electrode, a counter electrode and an electrolyte.
In the present invention, the reference electrode is preferably selected from one or more of a silver/silver chloride electrode, a calomel electrode, and a mercury-oxidized mercury electrode; the counter electrode is preferably selected from one or more of nickel mesh electrode, platinum carbon electrode, glassy carbon electrode and carbon rod electrode; the electrolyte is preferably selected from KOH solution, naOH solution, KHCO 3 Solution of NaHCO 3 Solution, K 2 CO 3 Solution, na 2 CO 3 Solution, KCl solution, naCl solution, K 2 SO 4 Solution and Na 2 SO 4 One or more of the solutions.
In the present invention, the flow rate of the carbon dioxide gas in the methane production process is preferably 1 to 200sccm, more preferably 10 to 150sccm, still more preferably 50 to 120sccm, and most preferably 80 to 100sccm; the catholyte and anolyte flow rates are preferably independently selected from 0.1 to 100mL/min, more preferably 0.5 to 80mL/min, more preferably 1 to 60mL/min, more preferably 10 to 50mL/min, more preferably 20 to 40mL/min, most preferably 30mL/min.
In the present inventionThe potential in the potentiostatic method is preferably-0.1 to-2V, more preferably-0.5 to-1.5V, and most preferably-1V; the current density in the constant current method process is preferably 1-1000 mA/cm 2 More preferably 10 to 800mA/cm 2 More preferably 50 to 600mA/cm 2 More preferably 100 to 400mA/cm 2 Most preferably 200 to 300mA/cm 2 。
The invention provides a supported copper catalyst, which comprises a cerium oxide quantum dot carrier and a copper monoatomic active site. The preparation method of the copper catalyst provided by the invention has the advantages of low price of raw materials, simple operation and easy amplification. The carrier cerium oxide quantum dot is smaller than 10nm, has a large specific surface area, has a plurality of oxygen defects on the surface, can realize high load of copper on the surface, and has single-atom state distribution on the surface of the cerium oxide quantum dot, and the copper active site is isolated, so that the carbon-carbon coupling step is not easy to occur in the electrocatalytic carbon dioxide reduction process, and the generation of byproducts of ethylene, ethanol and propanol is reduced; the copper monoatomic active site also has stronger adsorption capacity to the carbon monoxide intermediate in the electrocatalytic carbon dioxide reduction process, so that the deep hydrogenation of the carbon monoxide intermediate is easy, and finally the catalyst shows very high methane product selectivity.
Example 1
Accurately weighing 868.4mg of cerium nitrate hexahydrate, adding the cerium nitrate hexahydrate into 50mL of triethylene glycol, heating the solution to 100 ℃ under magnetic stirring, and maintaining stirring for 30min to completely dissolve the cerium nitrate hexahydrate to obtain a reaction solution;
heating the reaction solution from 100 ℃ to 180 ℃ and maintaining 180 ℃ for 30min under the magnetic stirring state; then stopping heating and stirring, and naturally cooling the reaction liquid to room temperature to obtain a reaction product;
washing the reaction product by using a mixed solvent of ethanol and ethyl acetate (volume ratio is 1:7) and separatingSeparating the cores, then drying overnight in a vacuum drying oven at 60 ℃ to obtain the cerium oxide quantum dot catalyst, which is marked as CeO 2 QD。
Example 2
Accurately weighing 868.4mg of cerium nitrate hexahydrate, adding the cerium nitrate hexahydrate into 50mL of triethylene glycol, heating the solution to 100 ℃ under magnetic stirring, and maintaining stirring for 30min to completely dissolve the cerium nitrate hexahydrate to obtain a reaction solution;
heating the reaction solution from 100 ℃ to 180 ℃ and maintaining 180 ℃ for 30min under the magnetic stirring state; then stopping heating and stirring to naturally cool the reaction liquid to room temperature to obtain cooled reaction liquid;
adding 9.7mg of copper nitrate trihydrate into the cooled reaction solution, heating the solution to 100 ℃ under magnetic stirring, and maintaining stirring for 30min to completely dissolve the copper nitrate trihydrate to obtain a mixed solution;
heating the mixed solution from 100deg.C to 180deg.C, and maintaining 180deg.C under magnetic stirring for 30min; then stopping heating and stirring, and naturally cooling the reaction liquid to room temperature to obtain a reaction product;
washing the product by using a mixed solvent of ethanol and ethyl acetate (volume ratio is 1:7), centrifugally separating, and then placing the product in a vacuum drying oven at 60 ℃ for drying overnight to obtain the cerium oxide quantum dot supported copper catalyst with the molar ratio of copper to cerium of 2%, wherein the catalyst is marked as CeO 2 QD-2％Cu。
Example 3
The cerium oxide quantum dot-supported copper catalyst prepared according to the method of example 2 is different from example 2 in that the mass of copper nitrate trihydrate is added to be 33.8mg, and the cerium oxide quantum dot-supported copper catalyst with the molar ratio of copper to cerium of 7% is prepared and marked as CeO 2 QD-7％Cu。
Example 4
The cerium oxide quantum dot-supported copper catalyst prepared according to the method of example 2 is different from example 2 in that the added copper nitrate trihydrate has a mass of 48.3mg and the cerium oxide quantum dot-supported copper catalyst with a molar ratio of copper to cerium of 10% is preparedIs marked as CeO 2 QD-10％Cu。
FIG. 1 shows CeO obtained in example 4 2 As can be seen from the transmission electron microscope pictures of QD-10% Cu, the prepared CeO 2 The quantum dot size was about 2nm, and Cu atoms could not be observed from the spherical electron microscope image because Cu had an atomic number lower than Ce.
FIG. 2 shows CeO obtained in examples 1 to 4 2 QD，CeO 2 QD-2％Cu，CeO 2 QD-7% Cu and CeO 2 XRD diffraction patterns of QD-10% Cu, it can be seen that the XRD diffraction patterns of the four catalysts all conform to CeO of fluorite structure 2 Standard card, no diffraction peaks of copper, cuprous oxide and cupric oxide were observed, indicating Cu in CeO 2 The quantum dot surface exhibits a highly dispersed state.
FIG. 3 is a synchrotron radiation characterization of cerium oxide quantum dot supported copper catalysts with different copper to cerium molar ratios, showing CeO 2 QD-2％Cu，CeO 2 QD-7% Cu and CeO 2 Only Cu-O bonds were present in the QD-10% Cu samples, no Cu-Cu bonds were observed, indicating Cu in CeO 2 The quantum dot surface presents monoatomic state distribution.
Example 5
The method for generating methane by electrocatalytic reduction of carbon dioxide by using cerium oxide quantum dot supported copper catalyst comprises the following specific steps:
8mg of the cerium oxide quantum dot supported copper catalyst prepared in example 2 was added to 1.97mL of isopropanol solution, and then 30uL (microliter) of 5wt% Nafion solution was added, followed by ultrasonic mixing for 30min, to obtain a uniform catalyst mixed solution;
200uL (microliter) of the catalyst mixture was dropped onto a 1.5cm x 1.5cm gas diffusion electrode and baked under an infrared lamp to obtain a working electrode, wherein the catalyst loading was 0.36mg/cm 2 ；
Separating a cathode tank and an anode tank of a carbon dioxide reduction flow cell by using an anion exchange membrane, taking a silver/silver chloride electrode as a reference electrode, taking foam nickel as a counter electrode, and taking the prepared cerium oxide quantum dot supported copper catalyst coated gas diffusion electrode as working electricityElectrode, assembled electrocatalytic carbon dioxide reduction flow cell, working electrode active area of 1cm 2 ；
Using a peristaltic pump to continuously flow the electrolyte at a flow rate of 10mL/min by taking a KOH solution of 1.0M (mol/L) as the electrolyte of the cathode tank and the anode tank; high-purity carbon dioxide is continuously introduced into the back of the gas diffusion electrode of the cathode groove, and the flow speed is 50sccm; the electrocatalytic carbon dioxide reduction reaction was carried out using a constant current method, and constant currents were set to 50mA, 100mA, 200mA, 300mA, 400mA, 500mA, and 600mA, respectively.
Example 6
Methane was prepared according to the procedure of example 5, with the difference that the catalyst prepared in example 2 was replaced by the catalyst prepared in example 1.
Example 7
Methane was prepared according to the procedure of example 5, with the difference that the catalyst prepared in example 2 was replaced by the catalyst prepared in example 3.
Example 8
Methane was prepared according to the procedure of example 5, with the difference that the catalyst prepared in example 2 was replaced by the catalyst prepared in example 4.
Performance detection
Detecting a gas phase product of the electrocatalytic carbon dioxide reduction product by using a gas chromatograph, and detecting a liquid phase product by using a nuclear magnetic resonance spectrometer; according to the measured product quantity, the Faraday efficiency of the methane product and the current density of the methane part can be obtained through conversion by calculation according to Faraday law; the faraday efficiencies and methane partial current densities during methane production in examples 5 to 8 were measured, and the measurement results are shown in fig. 4 and 5.
FIG. 4 is a graph showing the Faraday efficiency of the electrocatalytic carbon dioxide reduction of a series of cerium oxide quantum dot supported copper catalysts with different copper to cerium molar ratios prepared in examples 1-4; it can be seen that the pure cerium oxide quantum dots (CeO 2 QD) produces little methane; when the molar ratio of copper to cerium was 2% (CeO 2 QD-2% Cu), the Faraday efficiency of methane is obviously improved and is 100-400 mA/cm 2 Under operation, the Faraday efficiency of methane can reach more than 40%; when the load continued to increase to a molar ratio of copper to cerium of 7% (CeO 2 QD-7% Cu), the Faraday efficiency of methane is further improved at 400mA/cm 2 When in operation, the Faraday efficiency of methane can reach 67%; when the copper loading was increased to a copper to cerium molar ratio of 10% (CeO) 2 QD-10% cu), the faraday efficiency of methane was not further improved, performance and CeO 2 QD-7% cu is almost; but at 600mA/cm 2 In operation, ceO 2 The QD-10% Cu can still maintain the Faraday efficiency of methane above 60%, and the current density of the corresponding methane part can reach 364mA/cm 2 (FIG. 5), exceeds the vast majority of reported copper-based catalysts.
Example 9
Methane was prepared according to the procedure of example 5, with the difference that the catalyst prepared in example 2 was replaced by the catalyst prepared in example 3.
Faraday efficiency was measured according to the method described in the above technical scheme, and the measurement result was that in the methane production process of example 9, the temperature was 200mA/cm 2 The long-time operation is about 3 hours, and the Faraday efficiency of methane can be maintained to be about 60% in the long-time electrolysis process.
Example 10
Methane was produced according to the method of example 5, differing from example 5 in that the catalyst prepared in example 4 was used in place of the catalyst prepared in example 2, and the catalyst loading on the gas diffusion electrode was 0.18mg/cm 2 。
Faraday efficiency was measured according to the method described in the above technical scheme, and the measurement result was that in the methane production process of example 10, the temperature was 300mA/cm 2 The faradaic efficiency of methane in the constant current reaction was 57.3%.
Example 11
Methane was produced according to the method of example 5, differing from example 5 in that the catalyst prepared in example 4 was used instead of the catalyst prepared in example 2, and the catalyst was supported on a gas diffusion electrodeThe amount was 1mg/cm 2 。
Faraday efficiency was measured according to the method described in the above technical scheme, and as a result, the measurement was performed at 300mA/cm during the methane production in example 11 2 The Faraday efficiency of methane in the constant current reaction is 50.1%
The invention provides a supported copper catalyst, which comprises a cerium oxide quantum dot carrier and a copper monoatomic active site. The preparation method of the copper catalyst provided by the invention has the advantages of low price of raw materials, simple operation and easy amplification. The carrier cerium oxide quantum dot is smaller than 10nm, has a large specific surface area, has a plurality of oxygen defects on the surface, can realize high load of copper on the surface, and has single-atom state distribution on the surface of the cerium oxide quantum dot, and the copper active site is isolated, so that the carbon-carbon coupling step is not easy to occur in the electrocatalytic carbon dioxide reduction process, and the generation of byproducts of ethylene, ethanol and propanol is reduced; the copper monoatomic active site also has stronger adsorption capacity to the carbon monoxide intermediate in the electrocatalytic carbon dioxide reduction process, so that the deep hydrogenation of the carbon monoxide intermediate is easy, and finally the catalyst shows very high methane product selectivity.
The above description of the embodiments is only intended to assist the understanding of the principles and methods of the invention, and it should be noted that it will be apparent to those skilled in the art that several improvements and modifications can be made to the invention without departing from the principles of the invention, which also fall within the scope of the claims.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
While the invention has been described and illustrated with reference to specific embodiments thereof, the description and illustration is not intended to limit the invention. It will be apparent to those skilled in the art that various changes may be made in this particular situation, material, composition of matter, substance, method or process without departing from the true spirit and scope of the invention as defined by the following claims, so as to adapt the objective, spirit and scope of the present application. All such modifications are intended to be within the scope of this appended claims. Although the methods disclosed herein have been described with reference to particular operations being performed in a particular order, it should be understood that these operations may be combined, sub-divided, or reordered to form an equivalent method without departing from the teachings of the present disclosure. Thus, unless specifically indicated herein, the order and grouping of operations is not a limitation of the present application.

Claims (8)

1. A method for preparing a supported copper catalyst, comprising:
mixing a copper source and a cerium source solution and then reacting to obtain a supported copper catalyst;
the supported copper catalyst comprises:
the carrier is cerium oxide quantum dots;
an active material, the active material being a copper atom.
2. The preparation method according to claim 1, wherein the molar ratio of copper to cerium in the supported copper catalyst is (1-20): 100.
3. the preparation method of claim 1, wherein the size of the cerium oxide quantum dot is 1-10 nm.
4. The method according to claim 1, wherein the copper atoms are distributed in a monoatomic state on the surface of the cerium oxide quantum dot.
5. The method according to claim 1, wherein the copper source is one or more selected from the group consisting of copper nitrate trihydrate, copper acetate, copper sulfate and copper acetylacetonate.
6. The method of preparing a cerium source solution according to claim 1, wherein the method of preparing a cerium source solution comprises:
and mixing the cerium source with a solvent for reaction to obtain a cerium source solution.
7. The preparation method according to claim 6, wherein the cerium source is selected from one or more of cerium nitrate hexahydrate, cerium acetate and cerium acetylacetonate;
the solvent is selected from polyols.
8. The preparation method according to claim 1, wherein the temperature of the mixing is 60-120 ℃;
the reaction temperature is 160-220 ℃.
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