CN114395769B - A kind of supported copper catalyst and its preparation method and application - Google Patents

Abstract

The invention provides a supported copper catalyst, the carrier of the supported copper catalyst is cerium oxide quantum dot, and the active material is copper single atom. The invention provides a preparation method of a supported copper catalyst. Polyhydric alcohol is used as a solvent, a stabilizer and a reducing agent, and the temperature is first raised to synthesize cerium oxide quantum dots. After the reaction solution is cooled, a copper source is added, and then the temperature is raised to obtain cerium oxide quantum dots. Copper single-atom catalysts. The preparation method of the supported copper catalyst provided by the invention is simple to operate and easy to scale up. When the electrocatalytic carbon dioxide reduction reaction is carried out by using a flow cell, high methane selectivity and methane partial current density can be obtained. The invention also provides the application of a supported copper catalyst.

Description

A kind of supported copper catalyst and its preparation method and application

technical field

The invention belongs to the technical field of electrocatalysis, and in particular relates to a supported copper catalyst and its preparation method and application, specifically a supported copper electrocatalyst and its preparation method and a method for preparing methane by electrocatalytically reducing carbon dioxide using the catalyst.

Background technique

Fossil energy is the main source of energy for social development and human production and life. As the final product of fossil energy use, carbon dioxide is emitted into the atmosphere. Excessive carbon dioxide emissions will lead to seawater acidification, greenhouse effect and many other environmental problems, which pose a huge threat to the sustainable development of human society.

The use of electrocatalytic methods to convert carbon dioxide and water into valuable products such as carbon monoxide, methane, and ethylene is considered to be a very promising method for the conversion and utilization of carbon dioxide. Carbon monoxide and formate can be prepared by using a variety of catalysts through two-electron transfer reduction and other methods. At present, high selectivity (Faraday efficiency greater than 95%), high current density (greater than 100mA/cm ² ) and long-term stability ( More than 100h) electrosynthesis. Methane is a very valuable carbon dioxide electroreduction product, which can be directly used in a very mature natural gas industrial system. However, carbon dioxide needs to obtain 8 electrons to be reduced to produce methane. At present, the preparation of methane with high selectivity and high current density is still is a challenge.

Contents of the invention

In view of this, the object of the present invention is to provide a supported copper catalyst and its preparation method and application. The supported copper catalyst provided by the present invention has exhibited higher methane selectivity and partial methane selectivity in electrocatalytic carbon dioxide reduction. current density.

The invention provides a supported copper catalyst, comprising:

Carrier, the carrier is cerium oxide quantum dots;

Active material, the active material is 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 dots is 1-10 nm.

Preferably, the copper atoms are distributed in a single-atom state on the surface of the cerium oxide quantum dots.

The present invention provides a preparation method of the supported copper catalyst described in the above technical scheme, comprising:

The copper source and the cerium source solution are mixed and then reacted to obtain a 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 comprises:

The cerium source and the solvent are mixed and then reacted 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 mixing temperature is 60-120°C;

The reaction temperature is 160-220°C.

The present invention provides an application of the supported copper catalyst described in the above technical solution in the preparation of methane.

Copper-based catalysts are currently the most widely studied electrocatalysts for the synthesis of more than two electron transfer reduction products, but in the present invention, the electrocatalytic carbon dioxide reduction reaction mechanism is complex, involving many steps such as CO bond breaking, CH bond and CC bond formation, etc. Therefore, the rational design of copper-based catalysts is the key to electrocatalytic conversion of methane with high activity and high selectivity. The present invention uses polyalcohol as a solvent, a stabilizer and a reducing agent, and synthesizes a copper single-atom catalyst supported by cerium oxide (CeO ₂ ) quantum dots through a two-step temperature-raising method. The present invention can prepare Cerium oxide quantum dot catalysts with different copper loadings.

The invention provides a supported copper catalyst, which comprises a cerium oxide quantum dot carrier and a copper single atom active site. The catalyst provided by the invention uses low-cost polyol as a solvent, a stabilizer and a reducing agent, and obtains a cerium oxide quantum dot-loaded copper catalyst through a simple two-step heating method. The preparation method of the catalyst provided by the invention uses low-cost raw materials, is simple to operate, and is easy to scale up.

In the catalyst provided by the present invention, the carrier cerium oxide quantum dot is less than 10nm, has a large specific surface area, and its surface has many oxygen defects, which can realize high loading of copper on the surface, and copper presents a single atom on the surface of the cerium oxide quantum dot Due to the isolation of copper active sites, the carbon-carbon coupling step is not easy to occur in the electrocatalytic carbon dioxide reduction process, which reduces the generation of by-products of ethylene, ethanol, and propanol; the copper single-atom active sites are also The carbon monoxide intermediate in the electrocatalytic carbon dioxide reduction process has a strong adsorption capacity, which makes the deep hydrogenation of the carbon monoxide intermediate easier, and finally shows a high methane product selectivity; at 200mA/cm ² ~ 600mA/cm ² In constant current reaction, methane faradaic efficiency of more than 60% can be achieved, the highest methane faradaic efficiency can be realized is 67%, and the highest methane partial current density is 364mA/cm ² , showing good potential for industrial application.

Description of drawings

Fig. 1 is the atomic-level resolution transmission electron micrograph of the cerium oxide quantum dot-supported copper catalyst with a 10% molar ratio of copper and cerium prepared in Example 4 of the present invention;

Fig. 2 is the XRD diffraction pattern of the cerium oxide quantum dot-loaded copper catalysts prepared in Examples 1-4 of the present invention with different molar ratios of copper and cerium;

Fig. 3 is the synchrotron radiation characterization of cerium oxide quantum dot-loaded copper catalysts with different copper and cerium molar ratios prepared in Examples 1 to 4 of the present invention;

4 is a broken line diagram of the faraday efficiency of electrocatalytic carbon dioxide reduction to methane produced by cerium oxide quantum dot-loaded copper catalysts with different copper and cerium molar ratios prepared in Examples 5 to 8 of the present invention;

Fig. 5 is a broken line diagram of the partial current density of methane corresponding to the electrocatalytic carbon dioxide reduction of cerium oxide quantum dot-supported copper catalysts prepared in Examples 5-8 of the present invention with different molar ratios of copper and cerium using a constant current method.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The invention provides a supported copper catalyst, comprising:

Carrier, the carrier is cerium oxide quantum dots;

Active material, the active material is copper atom.

In the present invention, the active substance is loaded on a carrier.

In the present invention, the size of the cerium oxide quantum dots is preferably 1-10 nm, more preferably 2-8 nm, more preferably 2-6 nm, most preferably 2-3 nm.

In the present invention, the copper atoms are preferably copper single atoms, and the copper atoms are preferably distributed in a single-atom state on the surface of the cerium oxide quantum dots.

In the present invention, the molar ratio of copper to cerium in the supported copper catalyst is preferably (1-20):100, more preferably (5-15):100, more preferably (8-12):100, The most preferred ratio is 10:100.

The present invention provides a preparation method of the supported copper catalyst described in the above technical scheme, comprising:

The copper source and the cerium source solution are mixed and then reacted to obtain a 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:

The cerium source and the solvent are mixed and then reacted 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 polyols, more preferably selected from one or more of triethylene glycol, diethylene glycol and ethylene glycol.

In the present invention, the dosage ratio of the cerium source and the solvent is preferably (100-2000) mg: (25-100) mL, more preferably (500-1500) mg: (30-90) mL, more preferably (800-1200) mg: (40-80) mL, most preferably 1000 mg: (50-70) mL.

In the present invention, the mixing of the cerium source and the solvent is recorded as the first mixing, and the first mixing is preferably carried out under stirring conditions; the temperature of the first mixing is preferably 60-120° C., more preferably 70° C. ~110°C, more preferably 80~100°C, most preferably 100°C; the time for the first mixing is preferably 10~60min, more preferably 20~50min, most preferably 30~40min.

In the present invention, the reaction carried out after the first mixing is recorded as the first reaction, and the first reaction is preferably carried out under stirring conditions; the temperature of the first reaction is preferably 160-220° C., more preferably 170° C. ~210°C, more preferably 180~200°C, most preferably 180°C; the time for the first reaction is preferably 10~120min, more preferably 30~100min, more preferably 50~80min, most preferably 60~ 70min.

In the present invention, the heating is preferably stopped after the first reaction is completed, and the obtained reaction solution is cooled 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 (1-20): 100, more preferably (5-15): 100, more preferably (8-12 ):100, most preferably 10:100.

In the present invention, the mixing of the copper source and the cerium source solution is recorded as the second mixing; the second mixing is preferably carried out under stirring conditions; the temperature of the second mixing is preferably 60 to 120°C, more preferably 70-110°C, more preferably 80-100°C, most preferably 100°C; the second mixing time is preferably 10-60 minutes, more preferably 20-50 minutes, most preferably 30-40 minutes.

In the present invention, the second mixed reaction is recorded as the second reaction; the second reaction is preferably carried out under stirring conditions; the temperature of the second reaction is preferably 160-220°C, more preferably 170°C ~210°C, more preferably 180~200°C, most preferably 180°C; the time for the second reaction is preferably 10~120min, more preferably 30~100min, more preferably 50~80min, most preferably 60~ 70min.

In the present invention, after the second reaction is completed, it is preferred to further include:

Heating was stopped, and the resulting reaction solution was cooled to room temperature.

In the present invention, after the second reaction is completed, it is preferred to further include:

The obtained reaction product is precipitated, washed and dried to obtain a supported copper catalyst.

In the present invention, the reagent of the precipitating agent is preferably a mixed solvent, more preferably including: a strong polar solvent and a weak polar solvent.

In the present invention, the strong polar solvent is preferably selected from methanol, one or more of ethanol and isopropanol; the weak polar solvent is preferably selected from ethyl acetate, normal hexane and cyclohexane One or more; the volume ratio of the strong polar solvent to the weak polar solvent is preferably (0.1～1):1, more preferably (0.3～0.7):1, more preferably (0.4～0.6): 1, most preferably 0.5:1.

The present invention provides an application of the supported copper catalyst described in the above technical solution in the preparation of methane.

In the present invention, the method for preparing methane is preferably electrocatalytic reduction of carbon dioxide to generate methane.

In the present invention, the preparation method of described methane more preferably comprises:

Using a three-electrode chemical system, constant current potential or constant current method to electrocatalyze the reduction of carbon dioxide to prepare methane;

The working electrode in the three-electrode chemical system is prepared from the supported copper catalyst described in the above technical solution.

In the present invention, the working electrode is preferably assembled into an electrocatalytic carbon dioxide reduction flow cell in the process of preparing methane by electrocatalytic carbon dioxide reduction.

In the present invention, the preparation method of the working electrode preferably includes:

Coating the catalyst ink on the surface of the gas diffusion electrode and drying it to obtain the working electrode;

The catalyst ink contains the copper-supported catalyst described in the above technical solution.

In the present invention, the preparation method of described catalyst ink preferably comprises:

The catalyst ink is obtained by mixing the supported copper catalyst described in the above technical solution and the Nafion solution in the dispersion liquid.

In the present invention, the mass concentration of the Nafion solution is preferably 0.1-10%, more preferably 0.5-8%, more preferably 1-6%, more preferably 2-5%, most preferably 3-4% .

In the present invention, the dispersion liquid is preferably selected from low boiling point solvents, more preferably selected from one or more of methanol, ethanol, propanol and isopropanol.

In the present invention, the volume ratio of the Nafion solution to the dispersion is preferably (0.001-1): 1, more preferably (0.005-0.8): 1, more preferably (0.01-0.6): 1, and more preferably (0.05-0.4):1, more preferably (0.1-0.3):1, most preferably 0.2:1.

In the present invention, the concentration of the supported copper catalyst in the catalyst ink is preferably 1-10 mg/mL, more preferably 2-8 mg/mL, more preferably 3-6 mg/mL, most preferably 4-5 mg/mL .

In the present invention, the mixing method is preferably ultrasonic to disperse the supported copper catalyst evenly.

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 supported copper catalyst in the catalyst ink on the gas diffusion electrode is preferably 0.05-5 mg/cm ² , more preferably 0.1-3 mg/cm ² , more preferably 0.5-2 mg/cm 2 ² , most preferably 0.7 mg/cm ² .

In the present invention, the three-electrode electrochemical system preferably further includes:

Reference electrode, counter electrode and electrolyte.

In the present invention, the reference electrode is preferably selected from one or more of silver/silver chloride electrode, calomel electrode and mercury-mercuric oxide electrode; the counter electrode is preferably selected from nickel mesh electrode, platinum mesh electrode One or more of electrodes, platinum carbon electrodes, glassy carbon electrodes and carbon rod electrodes; the electrolyte is preferably selected from KOH solution, NaOH solution, KHCO ₃ solution, NaHCO ₃ solution, K ₂ CO ₃ solution, Na ₂ One or more of CO ₃ solution, KCl solution, NaCl solution, K ₂ SO ₄ solution and Na ₂ SO ₄ solution.

In the present invention, the flow rate of carbon dioxide gas in the process of preparing methane is preferably 1 to 200 sccm, more preferably 10 to 150 sccm, more preferably 50 to 120 sccm, most preferably 80 to 100 sccm; catholyte and anolyte flow rate Preferably independently selected from 0.1-100mL/min, more preferably 0.5-80mL/min, more preferably 1-60mL/min, more preferably 10-50mL/min, more preferably 20-40mL/min, most preferably 30mL/min.

In the present invention, the potential in the process of the constant potential method is preferably -0.1～-2V, more preferably -0.5～-1.5V, most preferably -1V; the current density in the process of the constant current method is preferably 1-1000mA/cm ² , more preferably 10-800mA/cm ² , more preferably 50-600mA/cm ² , more preferably 100-400mA/cm ² , most preferably 200-300mA/cm ² .

The invention provides a supported copper catalyst, which includes a cerium oxide quantum dot carrier and a copper single-atom active site. During the preparation of the supported copper catalyst provided by the invention, an inexpensive polyol is used as a solvent, a stabilizer and a reducing agent , the cerium oxide quantum dot-loaded copper catalyst was obtained by a simple two-step heating method. The preparation method of the copper catalyst provided by the invention uses low-cost raw materials, is simple to operate, and is easy to scale up. The carrier cerium oxide quantum dots in the present invention are less than 10nm and have a large specific surface area. At the same time, the surface has many oxygen defects, which can realize high loading of copper on the surface. Copper presents a single-atom state distribution on the surface of the cerium oxide quantum dots. Due to the isolation of copper active sites, the carbon-carbon coupling step is not easy to occur in the electrocatalytic carbon dioxide reduction process, which reduces the generation of by-products of ethylene, ethanol, and propanol; The carbon monoxide intermediate in the process has a strong adsorption capacity, which makes the deep hydrogenation of the carbon monoxide intermediate easy, and finally makes the catalyst show a high methane product selectivity.

Example 1

Accurately weigh 868.4 mg of cerium nitrate hexahydrate, add it to 50 mL of triethylene glycol, heat the solution to 100°C under magnetic stirring, and keep stirring for 30 minutes to completely dissolve the cerium nitrate hexahydrate to obtain a reaction solution;

The above reaction solution was heated from 100°C to 180°C, and maintained at 180°C for 30 minutes under magnetic stirring; then, the heating and stirring were stopped, and the reaction solution was naturally cooled to room temperature to obtain the reaction product;

The above reaction product was washed with a mixed solvent of ethanol and ethyl acetate (volume ratio 1:7) and centrifuged, and then dried overnight in a vacuum oven at 60°C to obtain a cerium oxide quantum dot catalyst, labeled as CeO ₂ QD.

Example 2

Accurately weigh 868.4 mg of cerium nitrate hexahydrate, add it to 50 mL of triethylene glycol, heat the solution to 100°C under magnetic stirring, and keep stirring for 30 minutes to completely dissolve the cerium nitrate hexahydrate to obtain a reaction solution;

The above reaction solution was heated from 100°C to 180°C, and maintained at 180°C for 30 minutes under magnetic stirring; then, the heating and stirring were stopped, and the reaction solution was naturally cooled to room temperature to obtain the cooled reaction solution;

Add 9.7 mg of copper nitrate trihydrate to the above-mentioned cooled reaction solution, heat the solution to 100°C under magnetic stirring, and keep stirring for 30 minutes to completely dissolve the copper nitrate trihydrate to obtain a mixed solution;

The above mixed solution was heated from 100°C to 180°C, and maintained at 180°C for 30 minutes under magnetic stirring; then, the heating and stirring were stopped, and the reaction solution was naturally cooled to room temperature to obtain the reaction product;

The above product was washed with a mixed solvent of ethanol and ethyl acetate (volume ratio of 1:7) and centrifuged, and then placed in a vacuum oven at 60°C to dry overnight to obtain a cerium oxide quantum dot loading with a copper to cerium molar ratio of 2%. Copper catalyst, labeled CeO ₂ QD-2% Cu.

Example 3

According to the method of Example 2, the supported copper catalyst of cerium oxide quantum dots is prepared, and the difference from Example 2 is that the quality of adding copper nitrate trihydrate is 33.8mg, and the cerium oxide quantum dots with a molar ratio of copper to cerium of 7% are prepared. Supported copper catalyst, labeled _CeO2QD -7%Cu.

Example 4

According to the method of Example 2, the cerium oxide quantum dot-supported copper catalyst was prepared. The difference from Example 2 was that the quality of adding copper nitrate trihydrate was 48.3 mg, and the cerium oxide quantum dots with a copper to cerium molar ratio of 10% were prepared. Supported copper catalyst, labeled CeO ₂ QD-10% Cu.

Fig. 1 is the transmission electron microscope picture of the CeO ₂ QD-10%Cu prepared in Example 4, as can be seen, the CeO ₂ quantum dot size prepared is about 2nm, because the atomic number of Cu is lower than that of Ce, it cannot Cu atoms were observed from the spherical aberration electron microscope picture.

Fig. 2 is the XRD diffraction pattern of CeO ₂ QD prepared in Examples 1-4, CeO ₂ QD-2% Cu, CeO ₂ QD-7% Cu and CeO ₂ QD-10% Cu, it can be seen that these four The XRD diffraction patterns of the catalysts all conform to the CeO ₂ standard card with fluorite structure, and no diffraction peaks of copper, cuprous oxide and cupric oxide are observed, indicating that Cu is highly dispersed on the surface of CeO ₂ quantum dots.

Figure 3 is the synchrotron radiation characterization of _cerium oxide quantum dot _- supported copper catalysts with different molar ratios of copper and cerium. The _results show that only There are Cu-O bonds and no Cu-Cu bonds are observed, indicating that Cu presents a single-atom state distribution on the surface of _CeO2 quantum dots.

Example 5

Using cerium oxide quantum dot-supported copper catalyst to electrocatalyze the reduction of carbon dioxide to generate methane, the specific method is as follows:

8mg of the cerium oxide quantum dot supported copper catalyst prepared in Example 2 was added to 1.97mL of isopropanol solution, then 30uL (microliter) of 5wt% Nafion solution was added, and then ultrasonically mixed for 30min to obtain a uniform catalyst mixed solution ;

Get 200uL (microliter) of the above-mentioned catalyst mixed solution, drop-coat it on the gas diffusion electrode of 1.5cmⅹ1.5cm, bake and dry under the infrared lamp to obtain the working electrode, and the loading capacity of the catalyst is 0.36mg/cm ² at this moment;

The cathode tank and the anode tank of the carbon dioxide reduction flow cell are separated by an anion exchange membrane, the silver/silver chloride electrode is used as the reference electrode, and the nickel foam is used as the counter electrode, and the cerium oxide quantum dot-supported copper catalyst prepared above is coated with The gas diffusion electrode is used as the working electrode, and the electrocatalytic carbon dioxide reduction flow cell is assembled, and the active area of the working electrode is 1cm ² ;

Use 1.0M (mol/L) KOH solution as the electrolyte in the cathode and anode tanks, and use a peristaltic pump to continuously flow the electrolyte at a flow rate of 10mL/min; continuously inject high-purity carbon dioxide into the back of the gas diffusion electrode in the cathode tank. The electrocatalytic carbon dioxide reduction reaction is carried out using the constant current method, and the constant current is set to 50mA, 100mA, 200mA, 300mA, 400mA, 500mA and 600mA respectively.

Example 6

Methane was prepared according to the method of Example 5, the difference from Example 5 was that the catalyst prepared in Example 1 was used to replace the catalyst prepared in Example 2.

Example 7

Methane was prepared according to the method of Example 5, the difference from Example 5 was that the catalyst prepared in Example 3 was used to replace the catalyst prepared in Example 2.

Example 8

Methane was prepared according to the method of Example 5, the difference from Example 5 was that the catalyst prepared in Example 4 was used to replace the catalyst prepared in Example 2.

performance testing

Use a gas chromatograph to detect the gas phase product of the electrocatalytic carbon dioxide reduction product, and use a nuclear magnetic resonance spectrometer to detect the liquid phase product; according to the amount of the product obtained from the measurement, the Faraday efficiency of the methane product and the current density of the methane part can be obtained by calculating according to Faraday's law; The Faradaic efficiency and the partial current density of methane in the process of preparing methane in Examples 5-8 were tested, and the test results are shown in FIG. 4 and FIG. 5 .

Fig. 4 is a series of different copper and cerium oxide quantum dot-loaded copper catalysts prepared by embodiments 1 to 4. The electrocatalytic carbon dioxide reduction methane Faraday efficiency line diagram; it can be seen that the simple cerium oxide quantum dots ( CeO ₂ QD) produces almost no methane; when the molar ratio of copper to cerium is 2% (CeO ₂ QD-2%Cu), the faradaic efficiency of methane has been significantly improved, ^and methane The Faraday efficiency of methane can reach more than 40%; when the loading continues to increase to the molar ratio of copper and cerium of 7% (CeO ₂ QD-7% Cu), the Faraday efficiency of methane is further improved, and the operation at 400mA/cm ² , the Faradaic efficiency of methane can reach 67%; when the molar ratio of copper to cerium is increased to 10% (CeO ₂ QD-10%Cu), the Faradaic efficiency of methane has not been further improved, and the performance and CeO ₂ QD-7%Cu is almost the same; but when operating at 600mA/cm ² , CeO ₂ QD-10%Cu can still maintain the faradaic efficiency of methane above 60%, and the corresponding current density of methane can reach 364mA/cm ² (Fig. 5), exceeding the vast majority of reported copper-based catalysts.

Example 9

Methane was prepared according to the method of Example 5, the difference from Example 5 was that the catalyst prepared in Example 3 was used to replace the catalyst prepared in Example 2.

According to the method described in the above-mentioned technical solution, the Faraday efficiency test is carried out, and the test result is that in the process of preparing methane in Example 9, it runs at 200mA/cm for about 3 hours for a ^long time, and can maintain about 60% of methane in the long-term electrolysis process Faraday efficiency.

Example 10

Methane was prepared according to the method of Example 5, the difference from Example 5 was that the catalyst prepared in Example 4 was used instead of the catalyst prepared in Example 2, and the loading amount of the catalyst on the gas diffusion electrode was 0.18 mg/cm ² .

According to the method described in the above-mentioned technical solution, the Faraday efficiency is detected, and the test result is that, in the process of preparing methane in Example 10, the Faraday efficiency of methane is 57.3% at the time of 300mA/cm ² constant current reaction.

Example 11

Methane was prepared according to the method of Example 5, the difference from Example 5 was that the catalyst prepared in Example 4 was used instead of the catalyst prepared in Example 2, and the loading amount of the catalyst on the gas diffusion electrode was 1 mg/cm ² .

Carry out Faraday efficiency detection according to the method described in above-mentioned technical scheme, test result is, in the process of preparing methane in embodiment 11, the Faraday efficiency of methane is 50.1% when 300mA/cm ^constant current reaction

The invention provides a supported copper catalyst, which includes a cerium oxide quantum dot carrier and a copper single-atom active site. During the preparation of the supported copper catalyst provided by the invention, an inexpensive polyol is used as a solvent, a stabilizer and a reducing agent , the cerium oxide quantum dot-loaded copper catalyst was obtained by a simple two-step heating method. The preparation method of the copper catalyst provided by the invention uses low-cost raw materials, is simple to operate, and is easy to scale up. The carrier cerium oxide quantum dots in the present invention are less than 10nm and have a large specific surface area. At the same time, the surface has many oxygen defects, which can realize high loading of copper on the surface. Copper presents a single-atom state distribution on the surface of the cerium oxide quantum dots. Due to the isolation of copper active sites, the carbon-carbon coupling step is not easy to occur in the electrocatalytic carbon dioxide reduction process, which reduces the generation of by-products of ethylene, ethanol, and propanol; The carbon monoxide intermediate in the process has a strong adsorption capacity, which makes the deep hydrogenation of the carbon monoxide intermediate easy, and finally makes the catalyst show a high methane product selectivity.

The description of the above embodiments is only used to help understand the principles and methods of the invention. It should be pointed out that for those of ordinary skill in the art, some improvements and modifications can also be made to the present invention without departing from the principles of the present invention. These improvements and modifications also fall within the protection scope of the claims of the present invention.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not 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 particular embodiments of the invention, these descriptions and illustrations do not limit the invention. It will be clearly understood by those skilled in the art that various changes may be made to make a particular situation, material, composition of matter, substance , method or process suitable for the object, spirit and scope of the present application. All such modifications are intended to come within the scope of the claims appended hereto. Although methods disclosed herein have been described with reference to particular operations performed in a particular order, it should be understood that such operations may be combined, subdivided, or reordered to form equivalent methods without departing from the teachings of the invention. Thus, unless otherwise 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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