Halogen-doped copper-based electrocatalyst, preparation method and application thereof

Abstract

The application relates to the technical field of catalysts, in particular to a halogen-doped copper-based electrocatalyst and a preparation method and application thereof, a copper-containing compound is dissolved in water to form a single uniform solution to prepare solution A; a halogen compound is dissolved in water to form a single uniform solution to prepare solution B; solution B is slowly added to solution A and mixed thoroughly, an alcohol solution is added to form solution C; an alkali solution is slowly added to solution C, and then sufficient stirring is carried out to obtain a blue complex D; a reducing reagent is added to the blue complex D, and the blue complex D gradually forms a yellow suspension; the yellow suspension is centrifuged, washed with deionized water and ethanol alternately, and dried to obtain the halogen-doped copper-based electrocatalyst; the catalyst provided by the application is used for electrocatalytic reduction of CO2 to prepare ethylene, and compared with a catalyst without halogen modification, the smaller interplanar spacing of the catalyst makes the selectivity of the ethylene product be obviously improved.

Description

Technical Field

[0001] This invention relates to the field of electrocatalysis technology, and in particular to a halogen-doped copper-based electrocatalyst, its preparation method, and its application. Background Technology

[0002] As the core of the petrochemical industry, the ethylene industry can generate high economic benefits and has become an important basic industry in developed countries. Ethylene production is one of the important indicators of a country's level of petrochemical development.

[0003] Currently, the industrial production of ethylene is usually achieved through oil and natural gas cracking and coal gasification. These methods have many drawbacks, including requiring high temperatures and pressures, large quantities of high-quality petroleum as raw materials, demanding advanced equipment, and causing environmental pollution.

[0004] The strategy for building a green China aims to promote the low-carbon development of industrial energy. Electrocatalytic CO2 reduction to ethylene, driven by renewable energy sources, not only makes it possible to convert renewable energy sources such as solar and wind power into chemical energy, but also alleviates environmental and energy problems, making it a green and effective method. While copper (Cu) is an effective material for the electrocatalytic CO2 reduction to ethylene, its relatively low product selectivity and current density limit its practical development. Summary of the Invention

[0005] The purpose of this invention is to provide a halogen-doped copper-based electrocatalyst, its preparation method, and its application, which solves the problem that the low product selectivity and current density of copper limit the practical development of this field.

[0006] To achieve the above objectives, the present invention provides a method for preparing a halogen-doped copper-based electrocatalyst, comprising the following steps:

[0007] Solution A is prepared by dissolving a copper-containing compound in water to form a single homogeneous solution.

[0008] Solution B is prepared by dissolving a halogen compound in water to form a single homogeneous solution.

[0009] Solution B is slowly added to solution A and mixed thoroughly. After adding the alcohol solution, solution C is formed.

[0010] A alkali solution was slowly added to solution C, and then the mixture was stirred thoroughly to obtain a blue complex D.

[0011] When a reducing agent is added to the blue complex D, the blue complex D gradually forms a yellow suspension;

[0012] The yellow suspension was centrifuged, washed alternately with deionized water and ethanol, and dried to obtain a halogen-doped copper-based electrocatalyst.

[0013] Among them, in "dissolving a copper-containing compound in water to form a single homogeneous solution, thus obtaining solution A";

[0014] The copper-containing compound is one of copper chloride, copper nitrate, copper sulfate, and copper acetate, wherein the concentration of the copper salt is 0.1–2.0 mol / L.

[0015] Among them, in the sentence "Dissolve a halogen compound in water to form a single homogeneous solution to obtain solution B";

[0016] The halogen compound is one or more of sodium fluoride, ammonium fluoride, sodium chloride, ammonium chloride, sodium bromide, ammonium bromide, sodium iodide, and ammonium iodide, wherein the concentration of halide ions is 0.1–2.0 mol / L.

[0017] Among them, in the sentence "Slowly add solution B to solution A and mix thoroughly, then add alcohol solution to form solution C";

[0018] The volumes of solutions A and B are kept constant, so that Cu 2+ :X - The molar ratio of (X = F, Cl, Br, I) is 1:0.1 to 2; and the volume of the added alcohol is consistent with that of solution A.

[0019] Among them, in the sentence "Slowly add alkaline solution to solution C, and then stir thoroughly to obtain blue complex D";

[0020] The concentration ratio of the added alkali solution to solution A is 1:1 to 3.

[0021] Among them, in the sentence "Adding a reducing agent to blue complex D causes blue complex D to gradually form a yellow suspension";

[0022] The molar ratio of the added reducing agent to the copper source is 2 to 6:1.

[0023] Among them, in the sentence "Slowly add alkaline solution to solution C, and then stir thoroughly to obtain blue complex D";

[0024] The alkaline solution is either sodium hydroxide or potassium hydroxide, and its concentration is 1.0–4.0 mol / L.

[0025] Among them, in the sentence "Adding a reducing agent to blue complex D causes blue complex D to gradually form a yellow suspension";

[0026] The reducing agent is either ascorbic acid or glucose, with a concentration of 0.01–0.09 mol / L.

[0027] The present invention also includes a halogen-doped copper-based electrocatalyst, which is prepared by the method described above for preparing the halogen-doped copper-based electrocatalyst.

[0028] This invention also includes the application of a halogen-doped copper-based electrocatalyst, characterized in that the halogen-doped copper-based electrocatalyst is used in the electrocatalytic reduction of CO2 to ethylene, specifically including the following steps:

[0029] Hydrophobic carbon paper treated with the halogen-doped copper-based catalyst was used as the working electrode, with a catalyst loading of 0.8 mg / cm³. 2 Solid Ag / AgCl was used as the reference electrode, Pt or Ni was used as the counter electrode, and 1 mol / L KOH solution was used as the electrolyte solution. The electrocatalytic reduction of CO2 to ethylene was carried out in a three-electrode flow cell under the condition of 20 mL / min.

[0030] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0031] 1. The copper-based catalyst material prepared by the present invention using a simple wet chemical reduction method has the advantages of simple operation, mild reaction conditions, large-scale production capability, and broad application prospects.

[0032] 2. The interplanar spacing of the catalyst surface was compressed. The degree of interplanar spacing compression was precisely controlled by varying the content and type of halogen added. Reduced interplanar spacing means a smaller distance between active sites, potentially increasing the possibility of carbon-carbon coupling.

[0033] 3. The material of this invention exhibits excellent ethylene enhancement performance in the field of electrocatalytic CO2 reduction, contributing to the development of the ethylene industry. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0035] Figure 1 The images show the XRD patterns of Cu2O-Cu(OH)2 catalysts with different chlorine doping levels and the undoped catalyst in Example 1.

[0036] Figure 2 The image shows SEM images of Cu2O-Cu(OH)2 catalysts with different chlorine doping levels in Example 1.

[0037] Figure 3 The graph shows the performance of electrocatalytic CO2 reduction to ethylene using Cu2O-Cu(OH)2 materials with different chlorine doping levels in Example 1.

[0038] Figure 4 The image shows the XRD pattern of Cu2O-Cu(OH)2 catalysts doped with different halogens in Example 2.

[0039] Figure 5 The graph shows the performance of electrocatalytic CO2 reduction to ethylene production using Cu2O-Cu(OH)2 materials doped with different halogens in Example 2.

[0040] Figure 6 This is a flowchart of the preparation method of the halogen-doped copper-based electrocatalyst of the present invention. Detailed Implementation

[0041] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0042] The present invention discloses a method for preparing a halogen-doped copper-based electrocatalyst, which specifically includes the following steps:

[0043] S101: Dissolve a copper-containing compound in water to form a single homogeneous solution, thus obtaining solution A;

[0044] S102: Dissolve a halogen compound in water to form a single homogeneous solution to obtain solution B;

[0045] S103: Slowly add solution B to solution A and mix thoroughly. After adding the alcohol solution, solution C is formed.

[0046] S104: Slowly add an alkaline solution to solution C, and then stir thoroughly to obtain a blue complex D;

[0047] S105: Adding a reducing agent to the blue complex D causes the blue complex D to gradually form a yellow suspension;

[0048] S106: The yellow suspension was centrifuged, washed alternately with deionized water and ethanol, and dried to obtain a halogen-doped copper-based electrocatalyst.

[0049] Example 1:

[0050] Take 10 mL of 1.25 mol / L copper nitrate solution A and 10 mL of x mol / L sodium chloride solution B (x can be 0.1, 0.3, 0.5, 0.9, etc.), mix thoroughly, then add 10 mL of ethanol and stir until homogeneous to form solution C. Slowly add 15 mL of 3.33 mol / L potassium hydroxide solution to solution C, gradually forming a blue complex D. Slowly add 30 mL of 0.075 mol / L ascorbic acid solution to blue complex D, gradually turning it into a yellow suspension. Centrifuge the above yellow suspension, wash alternately with deionized water and ethanol, and dry to obtain a yellow powder, denoted here as xCl-Cu.

[0051] Comparative Example 1:

[0052] In Comparative Example 1, no halogen-containing compounds were added in step S102, and the other steps were completely consistent with those in Example 1, resulting in the synthesis of an undoped Cu catalyst.

[0053] Figure 1 As shown, the phase of the samples prepared with different chlorine doping amounts is Cu2O-Cu(OH)2. The successful preparation of the surface catalyst and the analysis of the two phases show that the doped catalyst materials are all shifted to a higher angle, and the 0.3Cl-Cu sample is the most obvious.

[0054] Figure 2 As shown, the synthesized Cu2O-Cu(OH)2 catalysts are all in a state where short rods and spheres coexist.

[0055] Figure 3 As shown, the 0.3Cl-Cu catalyst exhibits improved Faradaic efficiency for ethylene compared to the undoped catalyst, reaching 48.8%. This implies that the chlorine-introduced catalyst sample can improve the selectivity for ethylene.

[0056] Example 2:

[0057] Compared with Example 1, we changed the types of halogen-containing compounds in preparation step S102.

[0058] Take 10 mL of 1.25 mol / L copper nitrate solution A and 10 mL of 0.3 mol / L sodium hydroxide solution B (X = F, Br, I), mix thoroughly, and then add 10 mL of ethanol and stir until homogeneous to form solution C. Slowly add 15 mL of 3.33 mol / L potassium hydroxide solution to solution C, gradually forming a blue complex D. Slowly add 30 mL of 0.075 mol / L ascorbic acid solution to the blue complex D, and it gradually turns into a yellow suspension. Centrifuge the above yellow suspension, wash it alternately with deionized water and ethanol, and dry it to obtain a yellow powder, which is denoted as 0.3X-Cu.

[0059] Figure 4 As shown, when the type of dopant element is changed without changing the doping content, the XRD peaks of all materials shift to higher angles, but the degree of shift varies, with chlorine doping showing the most significant shift.

[0060] Figure 5 As shown, catalysts doped with different elements all improved the Faradaic efficiency of ethylene compared to undoped materials. Among them, 0.3Cl-Cu showed the most significant improvement, reaching 48.8%.

[0061] Example 3:

[0062] Compared with Example 1, the type of alcohol solution added in preparation step S103 was changed.

[0063] Take 10 mL of 1.25 mol / L copper nitrate solution A and 10 mL of x mol / L sodium chloride solution B (x can be 0.1, 0.3, 0.5, 0.9, etc.), mix thoroughly, then add 10 mL of ethylene glycol and stir until homogeneous to form solution C. Slowly add 15 mL of 3.33 mol / L potassium hydroxide solution to solution C, gradually forming a blue complex D. Slowly add 30 mL of 0.075 mol / L ascorbic acid solution to D, gradually turning it into a yellow suspension. Centrifuge the above yellow suspension, wash alternately with deionized water and ethanol, and dry to obtain a yellow powder, denoted here as yCl-Cu.

[0064] Example 4:

[0065] Application of a halogen-doped copper-based catalyst: A catalyst ink containing 4 mg / mL was prepared and 10 μL of perfluorosulfonic acid resin solution was added to increase the adhesion of the powder. This ink was then sprayed onto hydrophobic carbon paper with a loading of 1 mg / cm³. 2 It was applied in a flow cell reactor with a three-electrode system for the electrocatalytic CO2 reduction process.

[0066] The above-disclosed embodiments are merely one or more preferred embodiments of this application and should not be construed as limiting the scope of this application. Those skilled in the art can understand that all or part of the processes for implementing the above embodiments and equivalent changes made in accordance with the claims of this application still fall within the scope of this application.

Claims

1. Use of a halogen-doped copper-based electrocatalyst in the electrocatalytic reduction of CO2 to ethylene, characterized in that, The method for preparing the halogen-doped copper-based electrocatalyst comprises the following steps: dissolving a copper-containing compound in water to form a single homogeneous solution to prepare solution A; dissolving a halogen compound in water to form a single homogeneous solution to prepare solution B; slowly adding solution B to solution A and mixing thoroughly, and then adding an alcohol solution to form solution C; slowly adding a base solution to solution C and then stirring thoroughly to obtain blue complex D; adding a reducing agent to blue complex D, and blue complex D gradually forms a yellow suspension; centrifuging the yellow suspension, washing with deionized water and ethanol alternately, and drying to obtain the halogen-doped copper-based electrocatalyst.

2. Use of a halogen-doped copper-based electrocatalyst according to claim 1 for the electrocatalytic reduction of CO2 to ethylene, characterized in that, In "dissolving a copper-containing compound in water to form a single homogeneous solution to prepare solution A"; the copper-containing compound is one of copper chloride, copper nitrate, copper sulfate, and copper acetate, wherein the concentration of the copper salt is 0.1-2.0 mol / L.

3. Use of a halogen-doped copper-based electrocatalyst according to claim 1 for the electrocatalytic reduction of CO2 to ethylene, characterized in that, In "dissolving a halogen compound in water to form a single homogeneous solution to prepare solution B"; the halogen compound is one or more of sodium fluoride, ammonium fluoride, sodium chloride, ammonium chloride, sodium bromide, ammonium bromide, sodium iodide, and ammonium iodide, wherein the concentration of the halogen ion is 0.1-2.0 mol / L.

4. Use of the halogen-doped copper-based electrocatalyst according to claim 1 for the electrocatalytic reduction of CO2 to ethylene, characterized in that, In "slowly adding solution B to solution A and mixing thoroughly, and then adding an alcohol solution to form solution C"; the volume ratio of solution A to solution B is 1:1, and the alcohol solution is one of ethanol, propanol, ethylene glycol, and polyethylene glycol.

5. Use of the halogen-doped copper-based electrocatalyst according to claim 1 for the electrocatalytic reduction of CO2 to ethylene, characterized in that, In "slowly adding a base solution to solution C and then stirring thoroughly to obtain blue complex D"; the base solution is one of sodium hydroxide or potassium hydroxide, and the concentration is 1.0-4.0 mol / L.

6. Use of the halogen-doped copper-based electrocatalyst according to claim 1 for the electrocatalytic reduction of CO2 to ethylene, characterized in that, In "adding a reducing agent to blue complex D, and blue complex D gradually forms a yellow suspension"; the reducing agent is one of ascorbic acid or glucose, and the concentration is 0.01-0.09 mol / L.

7. Use of the halogen-doped copper-based electrocatalyst according to claim 1 for the electrocatalytic reduction of CO2 to ethylene, characterized in that, The halogen-doped copper-based electrocatalyst is used for electrocatalytic reduction of CO2 to produce ethylene, and the method comprises the following steps: The hydrophobic carbon paper treated by the halogen-doped copper-based catalyst as the working electrode, the catalyst loading is 0.8 mg / cm 2 , the solid Ag / AgCl as the reference electrode, the Pt or Ni as the counter electrode, and the 1 mol / L KOH solution as the electrolyte solution, the electrocatalytic CO2 reduction to produce ethylene product under the working condition of three-electrode flow cell, wherein the CO2 flow rate is 20 mL / min.

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