阅读说明：本技术 一种铜基二氧化碳电催化材料及其制备方法 (Copper-based carbon dioxide electrocatalytic material and preparation method thereof ) 是由 林鹏 陈聪聪 徐喆 曾燮榕 于 2020-04-17 设计创作，主要内容包括：本发明公开了一种铜基二氧化碳催化材料及其制备方法,其中,所述方法包括步骤：将氧化剂溶液和有机配体溶液混合,制得第一混合溶液；将金属铜放入所述混合溶液中,使所述有机配体吸附在金属铜的特定晶面,并使所述金属铜未被有机配体吸附的晶面发生氧化反应；对所述氧化反应后的金属铜进行清洗处理,去除吸附在所述金属铜晶面的有机配体；将清洗后的金属铜浸入含有还原剂与卤素离子盐的第二混合溶液中并混合,加热反应预定时间后,制得所述铜基二氧化碳电催化材料。采用本发明的还原方法可将卤族元素适量掺杂到金属铜中,从而提升催化剂的催化性能以及对多碳产物的选择性。(The invention discloses a copper-based carbon dioxide catalytic material and a preparation method thereof, wherein the method comprises the following steps: mixing an oxidant solution and an organic ligand solution to prepare a first mixed solution; putting metal copper into the mixed solution, so that the organic ligand is adsorbed on a specific crystal face of the metal copper, and the crystal face of the metal copper which is not adsorbed by the organic ligand is subjected to oxidation reaction; cleaning the metal copper after the oxidation reaction to remove the organic ligand adsorbed on the crystal face of the metal copper; and immersing the cleaned metal copper into a second mixed solution containing a reducing agent and a halogen ion salt, mixing, and heating for reaction for a preset time to obtain the copper-based carbon dioxide electrocatalytic material. The reduction method of the invention can dope proper amount of halogen element into the metal copper, thereby improving the catalytic performance of the catalyst and the selectivity of the multi-carbon product.)

1. The preparation method of the copper-based carbon dioxide electrocatalytic material is characterized by comprising the following steps:

mixing an oxidant solution and an organic ligand solution to prepare a first mixed solution;

putting metal copper into the mixed solution, so that the organic ligand is adsorbed on a specific crystal face of the metal copper, and the crystal face of the metal copper which is not adsorbed by the organic ligand is subjected to oxidation reaction;

cleaning the metal copper after the oxidation reaction to remove the organic ligand adsorbed on the crystal face of the metal copper;

and immersing the cleaned metal copper into a second mixed solution containing a reducing agent and a halogen ion salt, mixing, and heating for reaction for a preset time to obtain the copper-based carbon dioxide electrocatalytic material.

2. The preparation method of the copper-based carbon dioxide electrocatalytic material as set forth in claim 1, wherein the reducing agent is one or more of tartaric acid, nitrilotriacetic acid, hydroxylamine hydrochloride and sodium borohydride.

3. The method for preparing the copper-based carbon dioxide electrocatalytic material as claimed in claim 1, wherein the salt of the halogen ion is one or more of sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, cesium chloride, cesium bromide and cesium iodide.

4. The preparation method of the copper-based carbon dioxide electrocatalytic material as set forth in claim 1, wherein the heating temperature is 25-90 ℃ and the reaction time is 5-120 min.

5. The method for preparing the copper-based carbon dioxide electrocatalytic material as set forth in claim 1, wherein the concentration of the reducing agent in the second mixed solution is 1mM to 1M.

6. The method for preparing the copper-based carbon dioxide electrocatalytic material as set forth in claim 1, wherein the concentration of the salt of the halogen ion in the second mixed solution is 0.01mM to 2M.

7. The method for preparing the copper-based carbon dioxide electrocatalytic material as set forth in claim 1, wherein the oxidant solution is one or more selected from the group consisting of an aqueous hydrogen peroxide solution, a potassium persulfate solution, a sodium persulfate solution, an amine persulfate solution, and a potassium hydrogen peroxymonosulfate solution.

8. The method for preparing the copper-based carbon dioxide electrocatalytic material as claimed in claim 1, wherein the organic ligand is selected from one of dodecyl trimethyl ammonium chloride, dodecyl trimethyl ammonium bromide, hexadecyl trimethyl ammonium chloride, octadecyl trimethyl ammonium bromide, hexadecyl dimethyl benzyl ammonium chloride, octadecyl dimethyl benzyl ammonium chloride, ethylenediamine, sodium ethylenediamine tetraacetate, ammonia water, citric acid or nitrilotriacetic acid, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate or hexadecyl ammonium bromide.

9. The method for preparing the copper-based carbon dioxide electrocatalytic material as claimed in claim 1, wherein the metallic copper is selected from one or more of copper sheets, copper powders, copper blocks, copper meshes and copper wires.

10. A copper-based carbon dioxide electrocatalytic material characterized by being produced by the production method according to any one of claims 1 to 9.

Technical Field

The invention relates to the field of electrocatalytic materials, in particular to a copper-based carbon dioxide electrocatalytic material and a preparation method thereof.

Background

As is well known, CO₂The concentration in the atmosphere is increasing day by day, and CO is broken through at present₂Safety limit concentration (350 ppm). CO 2₂The emission and consumption of CO should be in a dynamic equilibrium state theoretically, but the rapid development of the industrialization process is accompanied by the large consumption of fossil fuels, so that CO is used₂Excessive emissions and accumulations can lead to a number of negative effects including greenhouse effect, ocean acidification, glacier thawing, etc., which can damage the environment in which humans live. CO 2₂The reduction of (a) can yield a range of chemicals including CO, formic acid and higher energy density multi-carbon organics (e.g., ethylene, ethanol, ethane, etc.) via CO₂The sustainable use of energy is realized by repeated utilization. Therefore, how to realize high-efficiency and high-selectivity reduction of CO₂Has become CO for multi-carbon organic matter₂The hot spot problem in the reduction field.

Metals and their oxides are the most common CO₂Electrocatalytic materials, wherein the copper-based catalysts can exhibit the most excellent selectivity to multi-carbon products. Among copper-based catalytic materials, copper-based materials (OD-Cu) prepared by oxidizing a copper sheet first and then reducing the copper sheet have received much attention. The reason is that the surface appearance of the copper is changed in the oxidation process, the surface roughness is obviously increased, a large number of crystal boundaries are generated, partial oxygen is remained on the sub-surface of the copper obtained after reduction, and the characteristics can obviously increase the CO on the surface of the material₂Electrocatalytic activityAnd the catalytic efficiency is improved. At present, the method for preparing the OD-Cu material mainly comprises the steps of oxidizing a copper sheet by artificially creating an oxidizing environment to obtain a copper oxide, then taking the prepared copper oxide as a cathode to perform an electrochemical reaction, and reducing the copper oxide to copper through a negative voltage to obtain the stable OD-Cu material.

Although the oxidation-reduction treatment can obviously improve the catalytic performance of the copper-based material, the reduction process of the solid copper oxide precursor is a negative voltage electric reduction mode. When the copper sheet is reduced by adopting a negative voltage electric reduction mode, the final product is still the copper sheet which is used for reducing CO₂The improvement of catalytic performance of the catalyst is limited; when the copper powder is reduced by adopting a negative voltage electric reduction mode, nafion reagent is needed, however, part of CO in the copper powder can be blocked by the nafion reagent₂The active sites, or the pore structure of the copper powder itself, can cause the OD-Cu uniformity and catalytic performance to be affected.

Accordingly, the prior art is yet to be improved and developed.

Disclosure of Invention

In view of the defects of the prior art, the invention aims to provide a copper-based carbon dioxide electrocatalytic material and a preparation method thereof, and aims to solve the problem that the CO of the prepared OD-Cu is caused by reducing a solid copper oxide precursor by adopting a negative voltage reduction mode in the prior art₂Poor catalytic performance.

The technical scheme of the invention is as follows:

a preparation method of a copper-based carbon dioxide electrocatalytic material comprises the following steps:

mixing an oxidant solution and an organic ligand solution to prepare a first mixed solution;

putting metal copper into the mixed solution, so that the organic ligand is adsorbed on a specific crystal face of the metal copper, and the crystal face of the metal copper which is not adsorbed by the organic ligand is subjected to oxidation reaction;

cleaning the metal copper after the oxidation reaction to remove the organic ligand adsorbed on the crystal face of the metal copper;

and immersing the cleaned metal copper into a second mixed solution containing a reducing agent and a halogen ion salt, mixing, and heating for reaction for a preset time to obtain the copper-based carbon dioxide electrocatalytic material.

The preparation method of the copper-based carbon dioxide electrocatalytic material comprises the step of preparing a copper-based carbon dioxide electrocatalytic material, wherein the reducing agent is one or more of tartaric acid, nitrilotriacetic acid, hydroxylamine hydrochloride and sodium borohydride.

The preparation method of the copper-based carbon dioxide electrocatalytic material comprises the step of preparing a copper-based carbon dioxide electrocatalytic material, wherein the halogen ion salt is one or more of sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, cesium chloride, cesium bromide and cesium iodide.

The preparation method of the copper-based carbon dioxide electrocatalytic material comprises the steps of heating at 25-90 ℃ and reacting for 5-120 min.

The preparation method of the copper-based carbon dioxide electrocatalytic material is characterized in that the concentration of the reducing agent in the second mixed solution is 1 mM-1M.

The preparation method of the copper-based carbon dioxide electrocatalytic material is characterized in that the concentration of the halogen ion salt in the second mixed solution is 0.01 mM-2M.

The preparation method of the copper-based carbon dioxide electrocatalytic material comprises the step of selecting one or more of an oxidant solution, a hydrogen peroxide solution, a potassium persulfate solution, a sodium persulfate solution, an amine persulfate solution and a potassium hydrogen peroxymonosulfate solution.

The preparation method of the copper-based carbon dioxide electrocatalytic material comprises the step of selecting the organic ligand from one of dodecyl trimethyl ammonium chloride, dodecyl trimethyl ammonium bromide, hexadecyl trimethyl ammonium chloride, octadecyl trimethyl ammonium bromide, hexadecyl dimethyl benzyl ammonium chloride, octadecyl dimethyl benzyl ammonium chloride, ethylenediamine, sodium ethylene diamine tetraacetate, ammonia water, citric acid or nitrilotriacetic acid, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate or hexadecyl ammonium bromide.

The preparation method of the copper-based carbon dioxide electrocatalytic material comprises the step of preparing a copper-based carbon dioxide electrocatalytic material, wherein the metal copper is selected from one or more of copper sheets, copper powder, copper blocks, copper nets and copper wires.

The copper-based carbon dioxide electrocatalytic material is characterized by being prepared by the preparation method.

Has the advantages that: compared with the prior OD-Cu material preparation methods which are negative voltage electrical reduction, the method introduces a new reduction method, and reduces the metal copper after oxidation treatment by using a second mixed solution containing halogen ion salt and a reducing agent, thereby preparing the novel OD-Cu material. The reduction method of the invention can dope proper amount of halogen elements into the metallic copper, thereby improving the CO of the catalyst₂Catalytic performance and selectivity to multi-carbon products (ethylene, ethanol); when the chemical reduction method is adopted to reduce the oxidized metal copper sheet, the copper powder can be peeled off from the surface of the metal copper sheet, so that the complete reaction is carried out and the CO is increased₂The stripped copper powder can be further optimized and regulated in performance by utilizing different substrates; when the chemical reduction method is adopted to reduce the oxidized metal copper powder, no nafion reagent is needed to be added, and the phenomenon that the nafion reagent blocks CO of the copper powder can be effectively avoided₂The active site can prepare the OD-Cu material with better uniformity and catalytic performance. Aiming at the defects of a negative piezoelectric reduction method commonly adopted in the prior OD-Cu preparation, the invention firstly provides a new OD-Cu preparation idea based on a liquid-phase chemical reduction method (without voltage application), realizes the regulation and control of the crystal structure of a copper-based material and the doping of halogen elements in the oxidation and reduction processes, can randomly select a substrate material, and is expected to further promote the CO doping of OD-Cu₂Catalytic performance and selectivity to multi-carbon products.

Drawings

FIG. 1 is a flow chart of a preparation method of a copper-based carbon dioxide electrocatalytic material.

FIG. 2 is a graph comparing the Faraday efficiencies of OD-Cu materials prepared in examples 1-5 of the present invention at different voltages to produce C2.

FIG. 3 is a graph comparing the Faraday efficiencies of OD-Cu materials prepared in examples 3, 6 and 8 of the present invention at different voltages to produce C2.

Detailed Description

The invention provides a copper-based carbon dioxide electrocatalytic material and a preparation method thereof, and the invention is further described in detail below in order to make the purpose, technical scheme and effect of the invention clearer and more clear. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Referring to fig. 1, fig. 1 is a flow chart of a preferred embodiment of a method for preparing a copper-based carbon dioxide electrocatalytic material according to the present invention, as shown in fig. 1, wherein the method comprises the steps of:

s10, mixing the oxidant solution and the organic ligand solution to prepare a first mixed solution;

s20, putting the metal copper into the mixed solution, so that the organic ligand is adsorbed on the specific crystal face of the metal copper, and the crystal face of the metal copper which is not adsorbed by the organic ligand is subjected to oxidation reaction;

s30, cleaning the metal copper after the oxidation reaction to remove the organic ligand adsorbed on the crystal face of the metal copper;

and S40, immersing the cleaned metal copper into a second mixed solution containing a reducing agent and a halogen ion salt, mixing, and heating for reaction for a preset time to obtain the copper-based carbon dioxide electrocatalytic material.

Specifically, the conventional method for preparing an OD-Cu material mainly comprises oxidizing a copper sheet (powder) in an oxidizing environment to generate a copper oxide, and then performing an electrochemical reaction using the obtained copper oxide as a cathode to reduce the copper oxide to copper again, thereby obtaining a stable OD-Cu material, wherein the oxidation method includes air atmosphere thermal annealing, ammonium persulfate oxidation, oxygen plasma treatment, electrochemical oxidation, and the like. The OD-Cu material obtained by the existing oxidation-reduction preparation method obviously improves the CO content of copper sheets (powder)₂The preparation method can not realize the regulation and control of the crystal structure of the OD-Cu material, and researches show that the regulation and control of the crystal structure can realize the selectivity of a product after catalysis, and further improve the OD-Cu material toCO₂Electrocatalytic performance of.

In this embodiment, in order to realize the regulation and control of the crystal structure of the OD-Cu material, in the process of oxidizing metal copper, a suitable organic ligand is added, the organic ligand has higher binding energy to the specific crystal surface of the metal copper, when the addition amount of the organic ligand is appropriate, the organic ligand can be selectively adsorbed on the surface of the specific crystal surface of the metal copper, when the crystal surface of the metal copper is "protected" by the organic ligand, the crystal surface bound with the organic ligand can be prevented from being attacked by an oxidizing agent, and other crystal surfaces of unprotected metal copper are continuously corroded by an oxidizing agent and continuously converted into other crystal surfaces, so as to finally form a copper-based material with the specified crystal surface, and after the oxidation is finished, the organic ligand remaining on the surface is cleaned and removed for multiple times, and finally, soaking the cleaned metal copper into a second mixed solution containing a reducing agent and a halogen ion salt, mixing, and heating for reaction for a preset time to obtain the copper-based carbon dioxide electrocatalytic material. In this embodiment, by adding different kinds and concentrations of organic ligands during the oxidation process, for example, the organic ligands can be selectively adsorbed on the surface of Cu (100) or CuO (100) crystal planes, a large number of Cu (100) or CuO (100) crystal planes are protected by the organic ligands, so as to avoid further reaction consumption, unprotected (111), (110) crystal planes and other crystal planes are continuously reduced and converted into other crystal planes during the reduction process, and finally an OD-Cu material with a higher Cu (100) crystal plane is formed, during the reduction process, a halogen element in a reducing agent is doped into a Cu sheet (powder) to form OD-Cu containing a halogen element, and after the reduction process is completed, the residual reducing agent on the surface is cleaned and removed for multiple times. Compared with the prior reduction methods for preparing the OD-Cu material, which are negative voltage electrical reduction, the invention introduces a new reduction method, reduces the metal copper after oxidation treatment by using a second mixed solution containing halogen ion salt and a reducing agent, and properly dopes halogen elements into the metal copper by the reduction method, so that the CO content of the catalyst can be effectively improved₂Catalytic performance and selectivity to multi-carbon products (ethylene, ethanol).

In some embodiments, the metallic copper is selected from one or more of copper flakes, copper powder, copper nuggets, copper mesh, and copper wire. When the chemical reduction method is adopted to reduce the oxidized metal copper sheet, copper block, copper net or copper wire, the copper powder can be peeled off from the surface of the metal copper sheet, copper block, copper net or copper wire, so that the complete reaction is carried out and the CO is increased₂The stripped copper powder can be further optimized and regulated in performance by utilizing different substrates; when the chemical reduction method is adopted to reduce the oxidized metal copper powder, no nafion reagent is needed to be added, and the phenomenon that the nafion reagent blocks CO of the copper powder can be effectively avoided₂The active site can prepare the OD-Cu material with better uniformity and catalytic performance. Compared with the negative voltage electroreduction commonly adopted in the existing report, the invention firstly provides a novel OD-Cu preparation idea, realizes the synchronous regulation and control of the crystal structure of the copper-based material and the doping of halogen elements in the oxidation and reduction processes, and is expected to further promote the CO doping of the copper-based material₂Catalytic performance and selectivity to multi-carbon products.

In some embodiments, the reducing agent is one or more of tartaric acid, nitrilotriacetic acid, hydroxylamine hydrochloride, and sodium borohydride, but is not limited thereto; the concentration of the reducing agent in the second mixed solution is 1 mM-1M.

In some embodiments, the halogen ion salt is one or more of sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, cesium chloride, cesium bromide, and cesium iodide, but is not limited thereto; the concentration of the halogen ion salt in the second mixed solution is 0.01 mM-2M.

In some embodiments, in order to ensure that the crystal face of the oxidized metallic copper which is not protected by the organic ligand is fully reduced and doped with halogen elements, the cleaned metallic copper is immersed and mixed in a second mixed solution containing a reducing agent and a halogen ion salt, and the second mixed solution is heated to 25-90 ℃ to react for 5-120min, so as to obtain the copper-based carbon dioxide electrocatalytic material.

In some embodiments, the oxidant solution is selected from one or more of an aqueous hydrogen peroxide solution, a potassium persulfate solution, a sodium persulfate solution, an amine persulfate solution, and a potassium hydrogen peroxymonosulfate solution, but is not limited thereto. Hydrogen peroxide, potassium persulfate, sodium persulfate, ammonium persulfate, and potassium monopersulfate are commercially common oxidants, wherein potassium persulfate, sodium persulfate, ammonium persulfate, and potassium monopersulfate can be activated by hydroxide radicals in an alkaline environment to generate active oxidizing species. Under acidic and neutral conditions, each oxidant can be catalyzed by copper sheets and dissolved copper ions to generate active oxidation species.

In some embodiments, the oxidizer solution contains a basic compound at a concentration ranging from 0 to 5 mol/L. Potassium persulfate, sodium persulfate, ammonium persulfate and potassium monopersulfate oxidize copper in an alkaline environment, but the concentration range of alkaline compounds in the solution is 0-5mol/L, and the concentration exceeds 5mol/L, so that the oxidation reaction of copper is hindered, wherein the alkaline compounds can be common alkaline compounds such as potassium hydroxide, sodium hydroxide or ammonia water.

In some embodiments, the oxidizing agent solution comprises an acidic compound at a concentration ranging from 0 to 2 mol/L. The copper is oxidized by hydrogen peroxide in an acidic environment, the concentration of an acidic compound cannot exceed 2mol/L, and the copper oxidation reaction is hindered by exceeding the concentration, wherein the acidic compound can be common acidic compounds such as sulfuric acid, hydrochloric acid, nitric acid, perchloric acid and the like.

In some embodiments, because different types of organic ligands have different binding energies with different crystal faces in the metal copper, when the concentration of the organic ligands is moderate, the different types of organic ligands can be selectively adsorbed on the crystal faces of the metal copper with higher binding energy, so that the crystal faces are protected. In this embodiment, the organic ligand is selected from one of dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium bromide, hexadecyldimethylbenzylammonium chloride, octadecyldimethylbenzylammonium chloride, ethylenediamine, sodium ethylenediamine tetraacetate, ammonia water, citric acid or nitrilotriacetic acid, sodium dodecylsulfate, sodium dodecylbenzenesulfonate or hexadecylammonium bromide, but is not limited thereto.

In some specific embodiments, taking sodium dodecylbenzene sulfonate as an example, mixing the sodium dodecylbenzene sulfonate with an oxidant solution to prepare a mixed solution, placing the metal copper into the mixed solution to perform an oxidation reaction, wherein the sodium dodecylbenzene sulfonate has higher binding energy to a crystal face of Cu (100) or CuO (100), when the dosage of the sodium dodecylbenzene sulfonate is appropriate, the sodium dodecylbenzene sulfonate is selectively adsorbed on the surface of the crystal face of Cu (100) or CuO (100), and a large amount of crystal faces of Cu (100) or CuO (100) are prevented from being attacked by the oxidant because of being "protected" by the sodium dodecylbenzene sulfonate; the unprotected crystal faces of Cu (111), Cu (110) and the like are continuously corroded by the oxidant and continuously converted into other crystal faces; and after the oxidation is finished, the sodium dodecyl benzene sulfonate remaining on the surface is cleaned and removed for many times, and the OD-Cu material with a higher Cu (100) crystal face is finally formed after the reduction by a reducing agent and the doping by halogen. Compared with the negative voltage electroreduction commonly adopted in the existing report, the invention firstly provides a novel OD-Cu preparation idea, realizes the synchronous regulation and control of the crystal structure of the copper-based material and the doping of halogen elements in the oxidation and reduction processes, and can further promote the CO doping of the copper-based material₂Catalytic performance and selectivity to multi-carbon products.

The preparation method of the copper-based carbon dioxide electrocatalytic material of the invention is further explained by the following specific examples: