A copper-based nanosheet catalyst, and a preparation method and application thereof
By preparing porous copper nanosheet catalysts, the problems of low efficiency and poor stability of existing copper-based catalysts in the electrocatalytic reduction of carbon dioxide to ethylene have been solved, achieving high efficiency and stable electrocatalytic performance and improving the prospects for industrial application.
Patent Information
- Application Number
- CN202510001216.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-02
- Publication Date
- 2026-07-03
AI Technical Summary
Existing copper-based catalysts exhibit low ethylene Faraday efficiency, low current density, and poor stability in the electrocatalytic reduction of carbon dioxide to ethylene, limiting their prospects for industrial application.
Copper oxide nanosheet precursors were prepared by precipitation and hydrothermal methods, and copper was deposited on PTFE films or hydrophobic carbon paper by magnetron sputtering. Porous copper nanosheet catalysts were prepared by combining ionomer binders, and finally, in-situ electrochemical reduction was carried out in a flow cell to form red porous copper nanosheet catalysts.
The electrode achieved a Faraday efficiency of 84% or higher for the conversion of carbon dioxide to ethylene at a high current density of 400 mA/cm2, and operated stably for more than 110 hours at this current density, demonstrating high catalytic activity and stability.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrocatalysis technology, specifically relating to a copper-based nanosheet catalyst and its preparation method, as well as its application in the electrocatalytic reduction of carbon dioxide to produce ethylene. Background Technology
[0002] Carbon dioxide emissions cause global greenhouse gas pollution, making it essential to strengthen carbon dioxide emission reduction and resource recycling. Currently, electrocatalytic carbon dioxide reduction is considered a promising method, with electrocatalysts playing a crucial role in the process. Therefore, developing and designing highly efficient electrocatalysts to convert carbon dioxide into high-value-added fuels and chemical feedstocks provides an effective and feasible pathway for renewable energy storage and is of great significance for mitigating fossil resource depletion and reducing carbon emissions.
[0003] Previous studies have found that copper-based catalysts are the most efficient catalysts for reducing carbon dioxide to hydrocarbons. Among the reduction products, multi-carbon-hydrogen and carbon-oxygen compounds such as ethylene or ethanol have higher energy densities and application value. However, due to issues involving C / C bond coupling and the linear scaling between the activation energy and binding energy of reaction intermediates, the selective production of ethylene reduction presents certain challenges. Furthermore, currently reported electrocatalytic reduction catalysts for carbon dioxide to ethylene still have some limiting problems, such as low current density and poor stability, which hinder their practical industrial application in ethylene production.
[0004] Therefore, it is necessary to design a copper-based catalyst material with high catalytic activity and a high number of surface active sites, which can achieve high ethylene Faradaic efficiency while also achieving high current density and good stability, thereby improving the industrial application prospects of electrocatalytic reduction of carbon dioxide to ethylene. Summary of the Invention
[0005] This invention addresses the shortcomings of existing copper-based catalysts in the electrocatalytic reduction of carbon dioxide, including low ethylene Faradaic efficiency, low current density, and poor stability. It provides a copper-based nanosheet catalyst and its preparation method. The copper-based nanosheet catalyst provided by this invention possesses a porous copper nanosheet structure. This porous nanosheet structure exhibits high surface active sites and adsorption coupling ability with intermediates, demonstrating excellent ethylene Faradaic efficiency, industrial-grade current density, and good stability in the electrocatalytic reduction of carbon dioxide to ethylene.
[0006] In a first aspect, the present invention provides a method for preparing a copper-based nanosheet catalyst, specifically comprising the following steps:
[0007] Step 1: Prepare copper oxide nanosheet precursors using precipitation and hydrothermal methods;
[0008] Step 2: Copper is deposited by magnetron sputtering on a PTFE film or hydrophobic carbon paper to obtain a copper-plated substrate;
[0009] Step 3: Disperse the copper oxide nanosheet precursor and ionomer binder in an alcohol aqueous solution to obtain a dispersion solution, load the dispersion solution onto the surface of a copper-plated substrate, and dry to obtain the working electrode;
[0010] Step 4: The prepared working electrode is placed in a flow cell to carry out in-situ electrochemical reduction of carbon dioxide to obtain a copper-based nanosheet catalyst.
[0011] Preferably, the precipitation method described in step one involves mixing and reacting a copper salt solution with an alkaline solution to obtain a blue copper hydroxide precursor solution.
[0012] Specifically, the copper salt is one or more of copper chloride, copper nitrate, or copper sulfate, and the concentration of the copper salt solution is preferably 0.01-0.05 mol / L. The alkaline solution is one or two of sodium hydroxide or potassium hydroxide solution, and the concentration is preferably 1-3 mol / L.
[0013] Specifically, the preferred volume ratio of copper salt solution to alkaline solution is (1-2.2):(1-2.2).
[0014] Preferably, the hydrothermal reaction in step one is carried out at a temperature of 100-180℃ for 10-24 hours. After the reaction is complete, the product is preferably washed by centrifugation and dried to obtain a black copper oxide nanosheet precursor. The drying temperature is preferably 40-80℃.
[0015] Preferably, in step two, the magnetron sputtering method involves sputtering copper onto the surface of a PTFE film or hydrophobic carbon paper to obtain a copper-plated substrate. The copper plating of the substrate using the magnetron sputtering method employs a copper target, and the operating conditions include a vacuum degree of 4.0 × 10⁻⁶. -4 -8.0×10 -4 Pa, argon gas is introduced, sputtering power is 100-200W, sputtering time is 1-5min, target stage heating temperature is 50-150℃, and bias power supply is 100-200V.
[0016] Preferably, the working electrode in step three is prepared by drop-coating or spray-coating a dispersion solution of copper oxide nanosheet precursor and ionomer binder on the surface of a copper-plated substrate.
[0017] Specifically, in step three, the copper oxide nanosheet precursor and ionomer binder are dispersed in an alcohol aqueous solution, and the dispersion process is accompanied by ultrasound, which helps to achieve uniform dispersion.
[0018] Specifically, the alcohol in the aqueous solution can be selected from isopropanol, methanol, ethanol, etc., and the volume ratio of alcohol to deionized water is 1:1 to 4:1.
[0019] Specifically, the ionomer binder is selected from Nafion, and the volume ratio of alcohol to ionomer binder is 5:1-10:1.
[0020] Specifically, after drop coating or spray coating, the working electrode loaded with copper oxide nanosheets is placed in a vacuum dryer at room temperature for 2-6 hours.
[0021] Specifically, the loading of copper oxide nanosheets on the working electrode substrate surface is 1-5 mg / cm³. 2 .
[0022] Preferably, the flow cell in step four uses potassium hydroxide solution as the electrolyte with a concentration of 1-7 mol / L, employs nickel foam or stainless steel mesh as the anode, uses a mercury / mercury oxide electrode as the reference electrode, and has a reduction current density of 100-500 mA / cm². 2 The reduction time was 2-4 hours, and the carbon dioxide gas supply rate was 5-20 mL / min during the reduction reaction. Finally, after in-situ electrocatalytic reduction, a red porous copper nanosheet catalyst was obtained on the working electrode substrate.
[0023] Specifically, the copper nanosheets on the working electrode substrate obtained in step four have a porous structure with pore sizes of 2-20 nm and nanosheet thicknesses of approximately 40-180 nm.
[0024] Secondly, this invention provides a method for preparing ethylene by electrocatalytic reduction of carbon dioxide, specifically:
[0025] Building upon step four, the anode is replaced with a nickel-copper alloy as the electrode material, and the anode uses a glycerol solution for the electrocatalytic reduction of carbon dioxide to produce ethylene. Ultimately, ethylene is obtained at the cathode, and formic acid is obtained at the anode, which can replace the oxygen evolution reaction at the anode.
[0026] Specifically, in the method for electrocatalytic reduction of carbon dioxide to produce ethylene, the cathode is the copper-based nanosheet catalyst prepared in step four, a flow cell is used, KOH solution is used as the electrolyte (concentration can be 1-7 mol / L), and the current density is 100-500 mA / cm². 2 The gas flow rate of carbon dioxide is 5-20 mL / min; the anode uses a nickel-copper alloy as the electrode material, with a nickel content preferably of 30-60 wt%; the anolyte is a glycerol-KOH aqueous solution with a glycerol concentration of 25 wt%-35 wt% and a KOH aqueous solution concentration of 5 wt%-15 wt% for electrocatalytic reaction.
[0027] The electrode prepared by the method described in this invention has a current of 400 mA / cm.2 At high current densities, the Faraday efficiency of carbon dioxide to ethylene can reach 84% or higher, and the electrode can operate at this current density for more than 110 hours.
[0028] Compared with the prior art, the present invention has the following superior effects:
[0029] 1. The copper-based nanosheet catalyst material of the present invention uses copper oxide nanosheets synthesized by precipitation and hydrothermal methods as precursors, and prepares red porous copper nanosheets by in-situ electrochemical reduction. The preparation method is economical and simple, the material preparation process is easy to operate, safe and non-toxic, the reaction conditions are mild, high pressure is not involved, and no complicated instruments and equipment are required. The product yield and purity are high, which is conducive to realizing large-scale production.
[0030] 2. The copper-based nanosheet catalyst prepared by this invention has a continuous porous structure with pore size of 2-20 nm and nanosheet thickness of 40-180 nm. The porous nanosheet structure has a high specific surface area and exposes more surface active sites. Moreover, the porous structure can provide more adsorption sites, enhance the adsorption of reaction intermediates, promote the CC coupling ability of intermediates, and effectively improve the catalytic activity and efficiency of electrocatalytic reduction of carbon dioxide.
[0031] 3. This invention uses copper-plated PTFE membranes or hydrophobic carbon paper as a substrate to support porous copper nanosheet catalysts to obtain a working electrode. This electrode exhibits excellent electrocatalytic reduction of carbon dioxide to ethylene in a flow cell reactor. The electrocatalytic reaction is simple and efficient, enabling large-scale continuous production. This electrode operates at 400 mA / cm². 2 At high current densities, the Faraday efficiency for the conversion of carbon dioxide to ethylene can reach over 84%, and the electrode can operate at this current density for over 110 hours, indicating that the catalyst material and electrode have excellent electrocatalytic activity and stability at high current densities.
[0032] 4. This invention also develops a novel nickel / copper electrode material for the oxidation of glycerol to prepare formic acid. This reaction occurs at the anode, replacing the oxygen evolution reaction, and can prepare formic acid at the anode while preparing ethylene at the cathode, thus achieving the preparation of two products in one reactor and improving the utilization efficiency of the equipment. Detailed Implementation
[0033] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.
[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Locational terms such as top and bottom, mentioned or possibly used in this specification, are defined relative to construction and are relative concepts, and therefore may vary depending on their location and usage.
[0035] Main raw material sources
[0036] The raw materials and equipment used in this embodiment are described below:
[0037] Copper chloride, sodium hydroxide, potassium hydroxide, isopropanol, glycerol; purchased from Xilong Reagent; purity >99.5%.
[0038] PTFE membrane and carbon paper, purchased from: Gaoshi Ruilian.
[0039] Nafion solution supplier: Xianfeng Nanomaterials, purity >98%.
[0040] Nickel-copper alloy electrode, purchased from Xi'an Taijin Materials Co., Ltd.
[0041] Example 1
[0042] First, prepare 10 ml of 0.01 mol / L copper chloride solution and 10 ml of 1 mol / L sodium hydroxide solution;
[0043] Subsequently, under stirring conditions, sodium hydroxide solution was rapidly added dropwise to copper chloride solution at a volume ratio of 1:1 to produce copper hydroxide precipitate, and stirring was continued to obtain a uniformly dispersed copper hydroxide precursor solution.
[0044] The precursor solution was transferred to a 50 mL hydrothermal reactor and heated at 140 °C for 10 h. After naturally cooling to room temperature, the product was centrifuged and washed several times with deionized water and anhydrous ethanol. The product was then dried overnight in a vacuum oven at 60 °C to prepare the black copper oxide nanosheet precursor.
[0045] Pretreatment of the PTFE membrane substrate: 1.5×3cm 2 The PTFE membrane was washed sequentially with ethanol and water for 30 minutes each, and then dried in a vacuum oven for 2 hours. The treated PTFE membrane substrate was then adhered to the magnetron sputtering target stage using high-temperature resistant tape, and the vacuum level in the magnetron sputtering chamber was evacuated to 6.0 × 10⁻⁶. -4 Pa, argon gas was introduced, and then the sputtering power was adjusted to 100W, the target stage temperature was 100℃, the bias voltage was 100V, and after sputtering for 3 minutes, the inner chamber pressure was removed, the copper-plated PTFE film was taken out and stored in a vacuum desiccator.
[0046] An isopropanol aqueous solution was prepared by mixing 500 μL of isopropanol and 250 μL of deionized water (2:1). Then, 13.5 mg of the prepared black copper oxide nanosheet precursor was weighed and added to the isopropanol aqueous solution, along with 100 μL of Nafion binder. The mixture was ultrasonically dispersed for 30 min. The copper oxide nanosheet dispersion was then sprayed onto a surface with an area of 1.5 × 3 cm using a spray gun. 2 On the copper-plated substrate surface, the loading of copper oxide nanosheets on the substrate is 3 mg / cm². 2 Then, it is placed in a vacuum oven and dried at room temperature for 4 hours to obtain the working electrode.
[0047] The prepared working electrode was installed in a flow electrolysis cell reactor, using a stainless steel mesh as the anode and a mercury / mercury oxide electrode as the reference electrode. The electrolyte was a 1 mol / L KOH solution. Carbon dioxide gas was continuously introduced into the flow cell gas chamber at a flow rate of 10 mL / min. The reduction current density was 300 mA / cm². 2 The reduction time was 4 hours. After the in-situ electrochemical reduction reaction, the working electrode was removed, and a red porous copper nanosheet catalyst was obtained on the electrode substrate surface. The copper nanosheet pore size was 2 nm and the nanosheet thickness was 180 nm.
[0048] The electrochemical reduction performance of carbon dioxide was tested using a working electrode supported on porous copper nanosheet catalyst obtained after in-situ electrochemical reduction. A flow electrolysis cell reactor was used, and the active area of the electrode in contact with the electrolyte was 0.5 × 2 cm. 2 A mercury / mercury oxide electrode was used as the reference electrode, and a 1 mol / L KOH solution was used as the cathode electrolyte. During the test, carbon dioxide gas was continuously introduced into the gas chamber at a flow rate of 10 mL / min. A peristaltic pump controlled the cathode electrolyte flow rate at 10 mL / min, continuously introducing it into the cathode electrolyte chamber. The anolyte was continuously introduced into the anolyte chamber via a gas-liquid mixing pump. The anolyte composition was 25 wt% glycerol and 5 wt% KOH aqueous solution. The anolyte electrode was a nickel-copper alloy (30 wt% nickel and 70 wt% copper) with an electrode area of 0.5 × 2 cm². 2 .
[0049] At a current density of 400 mA / cm 2 When the electrodes operated stably for 120 hours, the cathode achieved a maximum Faraday efficiency of 84% in ethylene production, while the anode achieved a current efficiency of 95% in formic acid production. This indicates that the reaction process exhibits high selectivity at both the anode and cathode.
[0050] Example 2
[0051] Prepare 10 ml of 0.05 mol / L copper nitrate solution and 22 ml of 3 mol / L potassium hydroxide solution; then, under stirring, rapidly add the potassium hydroxide solution dropwise to the copper nitrate solution at a volume ratio of 2.2:1 to produce copper hydroxide precipitate, and continue stirring to obtain a uniformly dispersed copper hydroxide precursor solution;
[0052] The precursor solution was transferred to a 50 mL hydrothermal reactor and heated at 180 °C for 17 h. After naturally cooling to room temperature, the product was centrifuged and washed several times with deionized water and anhydrous ethanol. The product was then dried overnight in a vacuum oven at 40 °C to prepare the black copper oxide nanosheet precursor.
[0053] Pretreatment of the hydrophobic carbon paper film substrate: 1.5×3cm 2 The hydrophobic carbon paper was washed sequentially in ethanol and water for 30 minutes each, and then dried in a vacuum oven for 2 hours. The treated hydrophobic carbon paper was then attached to the magnetron sputtering target stage using high-temperature resistant tape, and the vacuum level in the magnetron sputtering chamber was evacuated to 8.0 × 10⁻⁶. -4 Pa, argon gas was introduced, and then the sputtering power was adjusted to 200W, the target stage temperature was 50℃, the bias voltage was 200V, and after sputtering for 5 minutes, the inner chamber pressure was removed, the copper-plated hydrophobic carbon paper substrate was taken out and stored in a vacuum desiccator.
[0054] A methanol-water solution was prepared by mixing 500 μL of methanol and 125 μL of deionized water (4:1). Then, 4.5 mg of the prepared black copper oxide nanosheet precursor was weighed and added to the methanol-water solution, along with 66.7 μL of Nafion binder. The mixture was ultrasonically dispersed for 30 min. The copper oxide nanosheet dispersion was then sprayed onto a 1.5 × 3 cm² area using a spray gun. 2 On the copper-plated substrate surface, the loading of copper oxide nanosheets on the substrate is 1 mg / cm². 2 Then, it is placed in a vacuum oven and dried at room temperature for 6 hours to obtain the working electrode.
[0055] The prepared working electrode was installed in a flow electrolysis cell reactor, using a stainless steel mesh as the anode and a mercury / mercury oxide electrode as the reference electrode. The electrolyte was a 7 mol / L KOH solution. Carbon dioxide gas was continuously introduced into the flow cell gas chamber at a flow rate of 20 mL / min. The reduction current density was 100 mA / cm². 2 The reduction time was 2 hours. After the in-situ electrochemical reduction reaction, the working electrode was removed, and a red porous copper nanosheet catalyst was obtained on the electrode substrate surface. The copper nanosheet pore size was 20 nm and the nanosheet thickness was 110 nm.
[0056] The electrochemical reduction performance of carbon dioxide was tested using a working electrode supported on porous copper nanosheet catalyst obtained after in-situ electrochemical reduction. A flow electrolysis cell reactor was used, and the active area of the electrode in contact with the electrolyte was 0.5 × 2 cm. 2 A mercury / mercury oxide electrode was used as the reference electrode, and a 1 mol / L KOH solution was used as the cathode electrolyte. During the test, carbon dioxide gas was continuously introduced into the gas chamber at a flow rate of 10 mL / min. A peristaltic pump controlled the cathode electrolyte flow rate at 10 mL / min, continuously introducing it into the cathode electrolyte chamber. The anolyte was continuously introduced into the anolyte chamber via a gas-liquid mixing pump. The anolyte composition was 30 wt% glycerol and 10 wt% KOH aqueous solution. The electrode was a nickel-copper alloy (60 wt% nickel and 40 wt% copper) with an electrode area of 0.5 × 2 cm². 2 .
[0057] At a current density of 400 mA / cm 2 When the electrodes operated stably for 110 hours, the cathode achieved a maximum Faraday efficiency of 87% in preparing ethylene, while the anode achieved a current efficiency of 96% in preparing formic acid.
[0058] Example 3
[0059] Prepare 22 ml of 0.025 mol / L copper sulfate solution and 10 ml of 1.5 mol / L sodium hydroxide solution; then, under stirring, rapidly add the sodium hydroxide solution dropwise to the copper sulfate solution at a volume ratio of 1:2.2 to produce copper hydroxide precipitate, and continue stirring to obtain a uniformly dispersed copper hydroxide precursor solution;
[0060] The precursor solution was transferred to a 50 mL hydrothermal reactor and heated at 100 °C for 24 h. After naturally cooling to room temperature, the product was centrifuged and washed several times with deionized water and anhydrous ethanol. The product was then dried overnight in a vacuum oven at 80 °C to prepare the black copper oxide nanosheet precursor.
[0061] Pretreatment of the PTFE membrane substrate: 1.5×3cm 2 The PTFE membrane was washed sequentially with ethanol and water for 30 minutes each, and then dried in a vacuum oven for 2 hours. The treated PTFE membrane substrate was then adhered to the magnetron sputtering target stage using high-temperature resistant tape, and the vacuum level in the magnetron sputtering chamber was evacuated to 4.0 × 10⁻⁶. -4 Pa, argon gas was introduced, and then the sputtering power was adjusted to 150W, the target stage temperature was 150℃, the bias voltage was 150V, and after sputtering for 1 minute, the inner chamber pressure was removed, the copper-plated PTFE film was taken out and stored in a vacuum desiccator.
[0062] Prepare an ethanol-water solution by mixing 500 μL of ethanol and 500 μL of deionized water (1:1). Then, weigh 22.5 mg of the prepared black copper oxide nanosheet precursor and add it to the ethanol-water solution, along with 50 μL of Nafion binder. Disperse the solution ultrasonically for 30 min. Spray the copper oxide nanosheet dispersion onto a 1.5 × 3 cm² area using a spray gun. 2 On the copper-plated substrate surface, the loading of copper oxide nanosheets on the substrate is 5 mg / cm². 2 Then, it is placed in a vacuum oven and dried at room temperature for 2 hours to obtain the working electrode.
[0063] The prepared working electrode was installed in a flow electrolysis cell reactor, using nickel foam as the anode and a mercury / mercury oxide electrode as the reference electrode. The electrolyte was a 3.5 mol / L KOH solution. Carbon dioxide gas was continuously introduced into the flow cell gas chamber at a flow rate of 5 mL / min. The reduction current density was 500 mA / cm². 2 The reduction time was 3 hours. After the in-situ electrochemical reduction reaction, the working electrode was removed, and a red porous copper nanosheet catalyst was obtained on the electrode substrate surface. The copper nanosheet pore size was 11 nm and the nanosheet thickness was 40 nm.
[0064] The electrochemical reduction performance of carbon dioxide was tested using a working electrode supported on porous copper nanosheet catalyst obtained after in-situ electrochemical reduction. A flow electrolysis cell reactor was used, and the active area of the electrode in contact with the electrolyte was 0.5 × 2 cm. 2 A mercury / mercury oxide electrode was used as the reference electrode, and a 1 mol / L KOH solution was used as the cathode electrolyte. During the test, carbon dioxide gas was continuously introduced into the gas chamber at a flow rate of 10 mL / min. A peristaltic pump controlled the cathode electrolyte flow rate at 10 mL / min, continuously introducing it into the cathode electrolyte chamber. The anolyte was continuously introduced into the anolyte chamber via a gas-liquid mixing pump. The anolyte composition was 35 wt% glycerol and 15 wt% KOH aqueous solution. The electrode was a nickel-copper alloy (45 wt% nickel and 55 wt% copper) with an electrode area of 0.5 × 2 cm². 2 .
[0065] At a current density of 400 mA / cm 2 When the electrodes operated stably for 120 hours, the cathode achieved a maximum Faraday efficiency of 89% in preparing ethylene, while the anode achieved a current efficiency of 97% in preparing formic acid.
[0066] Comparative Example
[0067] Prepare 10 ml of 0.01 mol / L copper chloride solution and 10 ml of 1 mol / L sodium hydroxide solution; then, under stirring conditions, rapidly add the sodium hydroxide solution dropwise to the copper chloride solution at a volume ratio of 1:1 to produce copper hydroxide precipitate, and continue stirring to obtain a uniformly dispersed copper hydroxide precursor solution;
[0068] The precursor solution was transferred to a 50 mL hydrothermal reactor and heated at 140 °C for 10 h. After naturally cooling to room temperature, the product was centrifuged and washed several times with deionized water and anhydrous ethanol. The product was then dried overnight in a vacuum oven at 60 °C to prepare the black copper oxide nanosheet precursor.
[0069] Treatment of the PTFE membrane: 1.5×3cm 2 The PTFE membrane was washed in ethanol and water for 30 minutes each, and then dried in a vacuum oven for 2 hours.
[0070] An isopropanol aqueous solution was prepared by mixing 500 μL of isopropanol and 250 μL of deionized water (2:1). Then, 13.5 mg of the prepared black copper oxide nanosheet precursor was weighed and added to the isopropanol aqueous solution, along with 100 μL of Nafion binder. The mixture was ultrasonically dispersed for 30 min. The copper oxide nanosheet dispersion was then sprayed onto a surface with an area of 1.5 × 3 cm using a spray gun. 2 On the PTFE membrane, the copper loading on the substrate is 3 mg / cm³. 2 Then, it is placed in a vacuum oven and dried at room temperature for 4 hours to obtain the working electrode.
[0071] The prepared working electrode was installed in a flow electrolysis cell reactor, using a stainless steel mesh as the anode and a mercury / mercury oxide electrode as the reference electrode. The electrolyte was a 1 mol / L KOH solution. Carbon dioxide gas was continuously introduced into the flow cell gas chamber at a flow rate of 10 mL / min. The reduction current density was 300 mA / cm². 2 The reduction time was 4 hours. After the in-situ electrochemical reduction reaction, the working electrode was removed, and a red porous copper nanosheet catalyst was obtained on the electrode substrate surface. The copper nanosheet pore size was 5 nm and the nanosheet thickness was 150 nm.
[0072] The electrochemical reduction performance of carbon dioxide was tested using a working electrode supported on porous copper nanosheet catalyst obtained after in-situ electrochemical reduction. A flow electrolysis cell reactor was used, and the active area of the electrode in contact with the electrolyte was 0.5 × 2 cm. 2A mercury / mercury oxide electrode was used as the reference electrode, and a 1 mol / L KOH solution was used as the cathode electrolyte. During the test, carbon dioxide gas was continuously introduced into the gas chamber at a flow rate of 10 mL / min. A peristaltic pump controlled the cathode electrolyte flow rate at 10 mL / min, continuously introducing it into the cathode electrolyte chamber. The anolyte was continuously introduced into the anolyte chamber via a gas-liquid mixing pump. The anolyte composition was 25 wt% glycerol and 5 wt% KOH aqueous solution. The electrode was a nickel-copper alloy (30 wt% nickel and 70 wt% copper) with an electrode area of 0.5 × 2 cm². 2 .
[0073] At a current density of 400 mA / cm 2 When the electrodes were running for 120 hours, the cathode achieved a maximum Faraday efficiency of 43% in preparing ethylene, while the anode achieved a current efficiency of 65% in preparing formic acid.
[0074] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.
Claims
1. A method for preparing a copper-based nanosheet catalyst, characterized in that, Includes the following steps: Step 1: Prepare copper oxide nanosheet precursors using precipitation and hydrothermal methods; Step 2: Copper is deposited by magnetron sputtering on a PTFE film or hydrophobic carbon paper to obtain a copper-plated substrate; Step 3: Disperse the copper oxide nanosheet precursor and ionomer binder in an alcohol aqueous solution to obtain a dispersion solution, load the dispersion solution onto a copper-plated substrate, and dry to obtain the working electrode; Step 4: The prepared working electrode is placed in a flow cell to carry out in-situ electrochemical reduction of carbon dioxide to obtain a copper-based nanosheet catalyst.
2. The preparation method according to claim 1, characterized in that, The precipitation method described in step one involves mixing a copper salt solution and an alkaline solution. The copper salt is selected from one or more of copper chloride, copper nitrate, or copper sulfate, and the alkaline is selected from one or two of sodium hydroxide or potassium hydroxide. Preferably, the concentration of the copper salt solution is 0.01-0.05 mol / L, and the concentration of the alkaline solution is 1-3 mol / L; the preferred volume ratio of the copper salt solution to the alkaline solution is (1-2.2):(1-2.2).
3. The preparation method according to claim 1, characterized in that, The hydrothermal reaction temperature in step one is 100-180℃, and the reaction time is 10-24h.
4. The preparation method according to claim 1, characterized in that, The magnetron sputtering method described in step two involves sputtering copper onto the surface of a PIFE film or hydrophobic carbon paper. Preferably, the vacuum degree is 4.0x10 -4 -8.0x10 -4 Pa, argon gas is introduced, the sputtering power is 100-200 W, the sputtering time is 1-5 min, the target table heating temperature is 50-150 °C, and the bias power is 100-200 V.
5. The preparation method according to claim 1, characterized in that, In step three, the alcohol in the aqueous alcohol solution is isopropanol, ethanol, or methanol; Preferably, the volume ratio of alcohol to water is 1:1 to 4:1; And / or: the ionomer binder is Nafion; Preferably, the volume ratio of alcohol to ionomer binder is 5:1 to 10:1; Preferably, the loading method is drip coating or spray coating; Preferably, the drying conditions are vacuum drying at room temperature for 2-6 hours; Preferably, the copper oxide nanosheet loading on the surface of the working electrode substrate is 1-5 mg / cm³. 2 .
6. The preparation method according to claim 1, characterized in that, In the in-situ electrochemical reduction of carbon dioxide described in step four, potassium hydroxide solution is used as the electrolyte solution, and the electrolyte concentration is preferably 1-7 mol / L. Preferably, nickel foam or stainless steel mesh is used as the anode, and the reference electrode is a mercury / mercury oxide electrode; Preferably, the reduction current density is 100-500 mA / cm². 2 The reduction time is 2-4 hours, and the carbon dioxide gas flow rate is 5-20 mL / min.
7. A copper-based nanosheet catalyst, characterized in that, It is prepared according to the preparation method described in any one of claims 1-6, wherein the thickness of the porous copper nanosheets in the copper-based nanosheet catalyst material is 40-180 nm, and the pore size of the porous copper nanosheets is 2-20 nm.
8. A method for preparing ethylene by electrocatalytic reduction of carbon dioxide, characterized in that, The cathode electrode material is the copper-based nanosheet catalyst prepared by any one of claims 1-6 or the copper-based nanosheet catalyst of claim 7. The anode uses a nickel-copper alloy as the electrode material. The cathode electrolyte is a potassium hydroxide solution, and the anode electrolyte is a glycerol-KOH aqueous solution. Formic acid is obtained at the anode, and ethylene is obtained at the cathode. Preferably, the glycerol concentration in the anolyte is 25wt%-35wt%, and the KOH aqueous solution concentration is 5wt%-15wt%.
9. The method as described in claim 8, characterized in that, The nickel content in nickel-copper alloys is 30-60 wt%.