CN112359374A

CN112359374A - Electrocatalytic reduction of CO by copper-based composite material2In (1)

Info

Publication number: CN112359374A
Application number: CN202011316165.1A
Authority: CN
Inventors: 赵玉平
Original assignee: Individual
Current assignee: Xinjiang Dingchen Technology Co ltd
Priority date: 2020-11-22
Filing date: 2020-11-22
Publication date: 2021-02-12
Anticipated expiration: 2040-11-22
Also published as: CN112359374B

Abstract

The invention provides a copper-based composite material for electrocatalytic reduction of CO₂The application in the method is that the copper-based surface is hydrothermally formed with the thorn-shaped copper, so that the specific surface area and the active sites of the electrode material can be obviously improved, the electrode stability is good, and the obtained thorn-shaped copper is not easy to peel off and fall off; the service life of the copper-based alloy can be prolonged while the high ethylene conversion rate is ensured, the Faraday efficiency of the electrochemical conversion method is more than 60% and the ethylene selectivity is more than or equal to 40% under the electrolytic voltage of-1.8V vs Ag/AgCl.

Description

Electrocatalytic reduction of CO by copper-based composite material2In (1)

Technical Field

The invention belongs to the field of electrochemistry, and particularly relates to a preparation method of a long-life copper-based composite material, which is particularly suitable for application in the field of preparing ethylene by electrocatalytic reduction of carbon dioxide.

Technical Field

CO₂Chemical structure is stable, therefore CO₂The molecules are very difficult to activate and thus difficult to participate in the reaction, so that

Conventionally, it is converted by severe reaction conditions (e.g., high temperature and high pressure). Generally, researchers have used chemical reformation, mineralization, enzyme catalysis, and photocatalysis, electrocatalysis, etc. to overcome the large activation energy barrier of CO 2. In these methods, H is not required due to mild conditions of electrochemical reduction reaction₂The reaction pH is close to neutral as a raw material, and excellent clean energy compatibility has been attracting attention.

Electrochemical reduction is a means of reducing CO2 under relatively mild ambient conditions by applying an electric current such that CO2 is reduced at the cathode surface. Electrochemical reduction has the following advantages: the reduction product can be controlled by adjusting the electrolysis voltage, the electrolysis temperature and the electrolyte type; the electrolyte is convenient to recover; the electrolytic cell has simple structure and is convenient to manufacture, and is generally carried out at normal temperature; the electric energy for electrolysis can be generated from renewable energy sources such as solar energy, wind energy and geothermal energy; the electrochemical reaction system is compact and modularized, can be adjusted according to requirements, and is easy to be used in industrial factories.

Due to many factors, such as the types of electrodes, the types of solvents, the electrolysis voltage, the pressure, the temperature, etc., affecting the electrochemical reduction of CO2, the obtained products are also various, such as methanol, formic acid, methane, carbon monoxide, ethylene, etc., and various metals are classified into four major groups according to the distribution rule of the products.

(I) Copper (Cu) as a unique catalyst shows remarkable catalytic performance and can convert CO into CO₂Conversion to hydrocarbons and oxygenates, being the only one capable of converting CO with significant efficiency₂Metal electrocatalysts for reduction to hydrocarbons or oxygenated hydrocarbons, such as methane, ethylene, ethanol and propanol.

(II) the second metal, noble metals such as gold (Au), silver (Ag), zinc (Zn), palladium (Pd) and gallium (Ga), is selective for carbon monoxide (CO) and is mainly produced from CO.

(III) the third metal, tin (Sn), lead ((Pb), mercury (Hg), indium (In), cadmium (Cd), etc., which are mainly used for producing formate, is used for producing formic acid (HCOOH) and formate ((HCOO)^-) The most preferred catalyst of (1).

(N) a fourth metal selected from nickel (Ni), iron (Fe), platinum (Pt) and titanium (Ti), which reacts only with hydrogen evolution under a stable condition to generate hydrogen (H)₂) Without CO₂The reducing power of (c).

Among the various catalysts for electrochemical reduction of COZ, copper is considered to be the most promising catalyst for the formation of hydrocarbon compounds such as methane and ethylene. In recent years, highly selective copper-based electrocatalysts have attracted much attention from both domestic and foreign researchers because of their high energy density and ability to produce ethylene as a chemical raw material.

CN202010628183 discloses a dendritic copper electrode with hydrophobic surface, and its preparation method and application. The copper electrode provided by the invention comprises a gas diffusion layer and a copper layer deposited on the surface of the gas diffusion layer; the copper layer has a dendritic microstructure. The surface of the copper electrode provided by the invention consists of regular copper dendrites, the copper electrode shows good hydrophobicity, can effectively prevent the excessive contact of electrolyte, avoids the electrode from flooding and improves the stability of the electrode; and the dendritic copper can also efficiently enrich cations in the electrolyte to form a local high electric field, so that the carbon-carbon coupling rate is improved, and the electrode shows excellent electro-catalytic CO2 reduction activity.

CN201911278128 uses a copper alloy material with an amorphous structure as a catalyst, and performs an electrochemical reaction on CO2 to obtain a carbon-containing compound. The invention adopts the copper alloy material with an amorphous structure as a catalyst to directly prepare carbon-containing compounds such as alcohol, acid, ketone and the like by electrocatalytic reduction of CO 2. The copper alloy material can be prepared into various macroscopic forms such as a block form, a powder form and a film form, can be directly used as an electrocatalytic electrode material to be applied to a CO2 electrocatalytic reduction cell, and simultaneously improves the electrocatalytic activity and stability of the catalyst, thereby improving the performance and efficiency of the electrolytic cell. The synthesis method provided can effectively exert the cooperative catalytic performance among catalysts by regulating and controlling the composition and structure of the copper alloy material with an amorphous structure, further regulate and control the type of products, and selectively obtain different carbon-containing compounds such as alcohol, acid, ketone and the like.

CN201910713686 discloses a copper-based carbon dioxide electrocatalytic material and a preparation method thereof, wherein the method comprises the steps of: mixing an oxidant solution and an organic ligand solution to prepare a mixed solution; putting metal copper into the mixed solution, so that the organic ligand is adsorbed on part of specific crystal faces of the metal copper, and oxidation reaction is carried out on crystal faces of the metal copper which are not adsorbed by the organic ligand; and cleaning the metal copper after the oxidation reaction to remove the organic ligand adsorbed on the crystal face of the metal copper, and performing electrochemical reduction to obtain the OD-Cu carbon dioxide catalytic material with more specific crystal faces. According to the invention, by adding different types and concentrations of organic ligands in the oxidation process, on one hand, the regulation and control of different crystal structure of the OD-Cu material can be realized; on the other hand, the prepared OD-Cu material has the advantages of high surface roughness, high crystal boundary density and the like, and can preferentially expose crystal faces, so that the catalytic activity of the material on CO2 and the selectivity on a multi-carbon product can be remarkably improved.

CN201810661930 discloses a preparation method of flower-shaped copper oxide, which comprises the following steps: A) mixing an oxidant, a morphology control agent, a hydrophilic group surfactant and an alkaline compound in water to obtain an initial solution; the morphology control agent is selected from sodium tungstate, potassium tungstate, sodium molybdate, urea or ethylenediamine; B) and immersing the cleaned copper into the initial solution for hydrothermal reaction to obtain flower-shaped copper oxide. The application also provides a method for photoelectrocatalysis reduction of CO2 by using flower-shaped copper oxide as an electrode. The invention provides a method for preparing flower-shaped copper oxide by taking elemental copper as a copper source, and the flower-shaped copper oxide prepared by the method can be directly used as an electrode for photoelectrocatalytic reduction of CO2 without additional forming treatment.

CN201310254758 discloses a flower-shaped copper oxide/iron oxide nanotube catalyst and a preparation method thereof, wherein firstly a volcanic iron oxide nanotube grows on the upper surface of an iron-based substrate in situ by an electrochemical anodic oxidation method, then copper oxide with a flower-shaped structure is deposited on the iron oxide substrate by a pulse electrodeposition method, and the flower-shaped copper oxide/iron oxide nanotube catalyst is obtained after calcination. The catalyst obtained by the invention has good photoelectrocatalysis performance, and realizes the coupling of two reactions of water cracking and CO2 reduction, and the product is methanol and ethanol after the photoelectrocatalysis reduction of CO2 and gas chromatography detection and analysis.

The following problems are evident from the above patent: (1) as the most excellent ethylene selective catalyst, the catalyst has few research directions aiming at improving the ethylene selectivity, and the ethylene is the most important energy hydrogenation raw material in the chemical production; (2) the life of the electrocatalytic electrode was not studied; (3) the catalytic activity is to be improved.

Disclosure of Invention

Based on the problems, the key problem to be solved by the invention is to provide a copper-based composite material for electrocatalytic reduction of CO₂The electrode structure and the preparation technology can ensure high ethylene conversion rate and prolong the service life of the electrode structure.

The method comprises the following steps:

(1) pretreating the copper-based alloy;

(2) the copper-containing solution is used as electrolyte, the copper-based material is used as cathode, and electrochemical deposition reduction is carried out under extremely high negative bias.

(3) Chemically reducing the copper nanowire seed crystal at high temperature;

(4) the spiny copper-based composite material is obtained by hydrothermal treatment

(5) And (4) oxidizing.

Wherein the pretreatment in the step (1) comprises grinding and inorganic degreasing;

wherein the copper-containing electrolyte in the step (2) comprises copper sulfate, sulfuric acid, chloride ions and a surfactant, and the anode is an inert electrode or pure copper;

wherein the solution used in the high-temperature chemical reduction in the step (3) is a mixed solution of copper acetate and glycerol;

wherein the solution used in the step (4) is consistent with the solution in the step (3) in a closed state,

wherein the oxidizing solution used in the step (5) is a mixed solution of ammonia water and copper carbonate.

The copper-based alloy has the Faraday efficiency of more than 60% and the ethylene selectivity of more than or equal to 40% by an electrochemical conversion method under the electrolytic voltage of-1.8V vs Ag/AgCl.

Further, the copper-based alloy is a copper-nickel-cupronickel alloy, and the shape is a rod or a plate.

Further, the sanding is performed by using 200#, 600#, 1200# sandpaper in sequence.

Further, the degreasing is 15g/L Na₂CO₃、 10g/L Na₃PO₄ ^.12H₂O、10 g/L Na₂SiO₃At a temperature of 50 deg.C^oC, time 2 min.

Further, the copper-containing electrolyte: 140-150g/L CuSO₄ ^.5H₂O；30-35g/L H₂SO₄；40-45g/L Cl^-(ii) a 0.5-1g/L APEO; temperature is 25-30 DEG C^oC; the direct current constant voltage is-13V, and the time is 5s-10 s.

Further, the solution used in the high-temperature chemical reduction in the step (3): 3-5M anhydrous copper acetate in 300-350 deg.C^oAnd C, keeping the state of non-sealing for 15-20 min.

Further, the hydrothermal temperature in the step (4) is 110-^oC, the time is 12-24 h.

Further, the reaction kettle of the step (3) and the reaction kettle of the step (4) are stainless steel lining-free hydrothermal reaction kettles, and before the step (4), nitrogen is used for evacuating air in the reaction kettle of the step (3).

Further, the concentration of the ammonia water in the step (5) is 100-^oC。

Further, the long-life copper-based composite material is prepared from CO₂An electrocatalytic reduction electrode.

(1) Regarding the selection of the substrate: the copper-based alloy is a copper-nickel cupronickel alloy, is a copper-nickel binary alloy, has 5-10 wt% of nickel, has better corrosion resistance on the premise of meeting the mechanical strength, and has nickel in CO₂Without any catalytic reduction of CO in the electrocatalysis process₂The ability of nickel to cause no side reactions and not affect the conversion of the highly selective ethylene of the present invention, if brass (Cu-Zn) or bronze (Cu-Sn) alloy is used, Zn will electrocatalytically produce CO, and tin will electrocatalytically produce formic acid, which is not favorable for the purpose of the present invention.

(2) Regarding the pretreatment of the substrate: grinding and degreasing, wherein grinding: sanding with 200#, 600#, 1200# sandpaper in sequence for smoothing the surface, which aims to reduce roughness, remove macroscopic defects such as scratches, oxide layers, corrosion marks and rusty spots on the surface, improve the surface smoothness and achieve sufficient degreasing degree of 15g/L Na₂CO₃、 10g/L Na₃PO₄ ^.12H₂O、10 g/L Na₂SiO₃At a temperature of 50 deg.C^oC, time 2min, degreasing used in the inventionThe solution does not contain strong alkaline sodium hydroxide, mainly because Na2CuO is formed by Cu + NaOH + O2₂And Na2CuO₂Can be decomposed into a CuO suitable oxide film in water, is not beneficial to robbing the surface, and comprises the steps of hot water washing and cold water washing, washing the surface of an article to be plated by deionized water heated to at least 45-50 ℃, removing residual alkali liquor on the surface, and washing by cold deionized water.

(3) Electrochemical deposition reduction is carried out under extremely high negative bias: in the copper-containing solution as electrolyte, copper-base alloy as cathode and inert or pure copper electrode as anode, and the direct current is switched on, the copper ions are reduced at the cathode, but because of the extremely high negative bias applied on the copper-base alloy plate, thus leading to a violent hydrogen evolution reaction, the hydrogen exists in the form of bubbles at the cathode, and because the hydrogen bubbles do not have metal ions at the place where the hydrogen bubbles appear, that is, any copper ion deposition reaction does not occur, so that the reaction of electrodepositing copper to form a compact structure is uniform at the cathode, thereby forming voids, as shown in figures 1, 2, 3 and 4, which, with increasing time, holes with different densities are formed on the surface of the copper base alloy, the density of the holes is closely related to voltage and time, the cathode deposition process can obviously increase the specific surface area of the cathode material, and the specific surface area of the polished copper-based alloy is approximately equal to 0 m.²(ii)/g; after 10s of cathodic deposition, the specific surface rises to 9m²G, if the time is increased, the cathode current density is reasonably adjusted, and the cathode current density can be obtained to be higher than 100m²A/g of three-dimensional porous copper material, but which also provides an active electrocatalytic reduction of CO directly by the above-mentioned method, albeit with a high specific surface area₂The activity, but the catalytic activity conversion, the ethylene selectivity and the Faraday efficiency are all low, and the preparation method can be consulted in the prior art.

The electro-deposition of the invention is carried out for 5s-10s in a very short time, the main purpose is to obtain a porous copper layer, the purpose is to 'dig pit' to facilitate the subsequent seed crystal attachment, and finally obtain the CO2 electro-catalytic material with high bonding strength and long service life through the subsequent hydrothermal reaction 'burying pit'.

The copper-containing electrolyte of the invention: 140-150g/L CuSO₄ ^.5H₂O；30-35g/L H₂SO₄；40-45g/L Cl^-(ii) a 0.5-1g/L APEO, where theoretical CuSO₄ ^.5H₂O may be about 230g/L, but is reduced in uSO because the solubility thereof causes precipitation of copper sulfate₄ ^.5H₂O is 140-150 g/L; the sulfuric acid can obviously reduce the resistance of the plating solution in the plating solution, can also prevent the hydrolysis of copper sulfate from forming copper hydroxide precipitate, the concentration of the sulfuric acid is lower than that of the actual copper plating, the sulfuric acid is usually more than 40g/L in the industry, and is beneficial to forming a flat plating layer, and when the concentration of the sulfuric acid is lower, a rough plating layer is easy to form, which is required by the invention; the APEO surfactant is added in the application, and is mainly used for improving the surface tension of the plating solution and avoiding excessive overflow of hydrogen bubbles.

Finally, the process should be optimally at rest without any stirring assistance.

(4) Regarding the high temperature chemical reduction of copper nanowire seeds: the process uses a 3-5M glycerol solution of anhydrous copper acetate, wherein the glycerol has a certain reducibility at normal temperature but no copper sulfate reducibility, and the glycerol solution has the temperature of 300 ℃ to 350 DEG C^oAnd C, under the condition of extremely strong reduction capability, copper sulfate can be reduced into copper polyhedral particles through electroless chemistry, the copper polyhedral particles can be adsorbed into the pits in the step (2) to be used as crystal seeds, the reaction kettle is not sealed in the process, the evaporation loss of the solution needs to be reduced to the greatest extent, and the main density of the process is that the crystal seeds are formed.

(5) The spinous copper-based composite material is obtained by hydrothermal treatment, and the hydrothermal temperature in the process is 110-120 DEG C^oAnd C, the time is 12-24h, before the step (4), the air in the reaction kettle in the step (3) is exhausted by using nitrogen, the nano copper can be shaped and grown by a hydrothermal method, the nano wire is obtained, and the copper-based electrode material with high specific surface area is further obtained.

To further illustrate the above operation, an ultra-fine cupronickel wire was used as the substrate, as shown in fig. 5; electrochemical deposition reduction is carried out by extremely high negative bias to form a porous copper layer on the surface, as shown in figure 6; then forming copper crystals in the pore channels by high-temperature electroless chemical reduction, as shown in figure 7; the spiny copper-based composite material obtained by the hydrothermal treatment is shown in figure 8, and the spiny copper on the surface of the copper material can be more obviously seen from figure 9.

(6) Regarding the oxidation: the purpose of the oxidation is to form CuO_XThe oxidation state metal has rich crystal boundary on the surface of the catalyst, and the specific crystal face shows stronger catalytic activity and selectivity, under the electrocatalytic condition of CO2, the oxide layer is electrochemically reduced to a metal layer, and the process activates the metal catalyst, a specific low coordination active site is formed on the surface of the catalyst, the reaction site of the competitive Hydrogen Evolution Reaction (HER) is blocked, the product selectivity is improved, the reduction activity of the copper-based electrode has strong dependence on the initial thickness of the copper-oxygen layer, the method has the advantages that the thickness of the oxide layer obtained by the method is 0.1-0.2 micron, the concentration of ammonia water is 100-120ml/L ammonia water solution with the mass fraction of 25wt.%, the concentration of copper carbonate is 40g/L, the time is 3-5min, and the temperature is 15-20.^oC, after oxidation, the thorn-shaped structure is slightly converged as shown in figure 10, XPS test is carried out on the oxidized copper oxide base material as shown in figure 11 fitting graph, and CuO is further confirmed_XIs present.

The beneficial technical effects are as follows:

(1) the electrode stability is good, and the obtained thorn-shaped copper is not easy to peel off.

(2) The copper thorn material obviously improves the contact specific surface area of reactants and electrodes and provides rich sites for catalytic reduction of CO 2.

（3）CuO_XThe layer effectively inhibits hydrogen evolution reaction, and the oxidation state is preferentially combined with H ions for reduction, so that the combination reaction of H and H is avoided.

(4) Has extremely high ethylene selectivity, high conversion rate and high Faraday efficiency.

Drawings

FIG. 1 is a SEM image of electrochemical deposition carried out at-13V under constant flow voltage for 2s according to the present invention.

FIG. 2 is a SEM image of electrochemical deposition carried out at-13V under constant flow voltage for 5s according to the present invention.

FIG. 3 is a SEM image of electrochemical deposition carried out at-13V under constant flow voltage for 7s according to the present invention.

FIG. 4 is a SEM image of electrochemical deposition carried out at-13V under constant flow voltage for 10s according to the present invention.

FIG. 5 is a TEM image of the invention on a copper wire.

FIG. 6 is a 10s TEM image of electrochemical deposition performed at-13V at a constant flow voltage according to the present invention.

FIG. 7 is a TEM image of electroless chemical reduction at high temperature according to the present invention.

Fig. 8 is a TEM image of a water heat of the present invention.

FIG. 9 is an SEM image of a spiny copper-based composite material obtained by the hydrothermal treatment of the present invention.

FIG. 10 is an SEM image of a spiny copper-based composite material obtained by the oxidation treatment of the present invention.

FIG. 11 is an XPS fit of a spiny copper-based composite material obtained by the oxidation treatment of the present invention.

Detailed Description

The following examples are given for the detailed implementation and specific operation of the present invention, but the scope of the present invention is not limited to the following examples.

Example 1

Electrocatalytic reduction of CO by copper-based composite material₂The copper-based composite material is prepared by the following steps:

(1) pretreating the copper-based alloy; the copper-based alloy is a copper-nickel-copper alloy.

Wherein the pretreatment in the step (1) comprises grinding and inorganic degreasing: the grinding is as follows: and sanding by using 200#, 600#, and 1200# sandpaper in sequence.

Defatting to 15g/L Na₂CO₃、 10g/L Na₃PO₄ ^.12H₂O、10 g/L Na₂SiO₃At a temperature of 50 deg.C^oC, time 2 min.

(2) Taking a copper-containing solution as an electrolyte, taking a copper-based alloy as a cathode, and carrying out electrochemical deposition reduction under extremely high negative bias.

Wherein the copper-containing electrolyte in the step (2) comprises sulfuric acidCopper, sulfuric acid, chloride ions and a surfactant, the anode is an inert electrode or pure copper, the copper-containing electrolyte: 140g/L CuSO₄ ^.5H₂O；30g/L H₂SO₄；40g/L Cl^-(ii) a 0.5g/L APEO; temperature 25^oC; the direct current constant voltage is-13V, and the time is 5 s.

(3) And (3) chemically reducing the copper nanowire seed crystal at high temperature.

Wherein the solution used in the high-temperature chemical reduction in the step (3) is a mixed solution of copper acetate and glycerol, and a glycerol solution of 3M anhydrous copper acetate at the temperature of 300 DEG C^oAnd C, keeping the state of non-sealing for 15 min.

(4) And carrying out hydrothermal treatment to obtain the thorn-shaped copper-based composite material.

Wherein the solution used in the step (4) is consistent with the solution in the step (3) in a closed state, and before the step (4), nitrogen is used for evacuating the air in the reaction kettle in the step (3).

The hydrothermal temperature in the step (4) is 110 DEG C^oC, the time is 12 h.

(5) And (4) oxidizing.

The ammonia water concentration is 100ml/L, the mass fraction is 25wt.% of ammonia water solution, 40g/L of copper carbonate, the time is 3min, and the temperature is 15%^oC。

Example 2

Wherein the copper-containing electrolyte in the step (2) comprises copper sulfate, sulfuric acid, chloride ions and a surfactant, the anode is an inert electrode or pure copper, and the copper-containing electrolyte comprises the following components in percentage by weight: 145g/L CuSO₄ ^.5H₂O；32.5g/L H₂SO₄；42.5g/L Cl^-(ii) a 0.75g/L APEO; temperature 27^oC; the direct current constant voltage is-13V, and the time is 8 s.

Wherein the solution used in the high-temperature chemical reduction in the step (3) is a mixed solution of copper acetate and glycerol, and a glycerol solution of 4M anhydrous copper acetate at the temperature of 320 DEG C^oAnd C, in an unsealed state, the time is 17.5 min.

The hydrothermal temperature in the step (4) is 115 DEG^oC, the time is 18 h.

(5) And (4) oxidizing.

The ammonia water concentration is 115ml/L, the mass fraction is 25wt.% of ammonia water solution, 40g/L of copper carbonate, the time is 4min, and the temperature is 17.5^oC。

Designated as S-2 sample.

Example 3

Wherein the copper-containing electrolyte in the step (2) comprises copper sulfate, sulfuric acid, chloride ions and a surfactant, the anode is an inert electrode or pure copper, and the copper-containing electrolyte comprises the following components in percentage by weight: 150g/L CuSO₄ ^.5H₂O； 35g/L H₂SO₄；45g/L Cl^-(ii) a 1g/L APEO; temperature 30^oC; the direct current constant voltage is-13V, and the time is 10 s.

Wherein the solution used in the high-temperature chemical reduction in the step (3) is a mixed solution of copper acetate and glycerol and a glycerol solution of 5M anhydrous copper acetate at the temperature of 350 DEG C^oAnd C, keeping the state of non-sealing for 20 min.

The hydrothermal temperature in the step (4) is 120 DEG^oC, the time is 24 h.

(5) And (4) oxidizing.

Ammonia water solution with concentration of 120ml/L and mass fraction of 25wt.%, copper carbonate of 40g/L, time of 5min, and temperature of 20%^oC。

Designated as S-3 sample.

Comparative example 1

Electrocatalytic reduction of CO by copper-based composite material₂The copper baseThe composite material is prepared by the following steps:

(2) And (3) chemically reducing the copper nanowire seed crystal at high temperature.

Wherein the solution used in the high-temperature chemical reduction in the step (2) is a mixed solution of copper acetate and glycerol and a glycerol solution of 5M anhydrous copper acetate at the temperature of 350 DEG C^oAnd C, keeping the state of non-sealing for 20 min.

(3) And carrying out hydrothermal treatment to obtain the thorn-shaped copper-based composite material.

Wherein the solution used in the step (3) is consistent with the solution in the step (2) in a closed state, and before the step (3), nitrogen is used for evacuating the air in the reaction kettle in the step (3).

The hydrothermal temperature in the step (3) is 120 DEG^oC, the time is 24 h.

(4) And (4) oxidizing.

Wherein the oxidizing solution used in the step (4) is a mixed solution of ammonia water and copper carbonate.

Designated as D-1 sample.

And (3) carrying out mechanical impact test on the ultrasonic oscillation S-3 and the D-1, wherein the test conditions are as follows: and (2) placing the copper-based composite material in a beaker filled with petroleum ether, sealing, oscillating and impacting for 60min in a 40 KHz/100 w ultrasonic cleaning instrument, taking out a sample, drying, and then determining the weight loss, wherein the mass loss of S-3 is 0.27wt.%, and the mass loss of D-1 is 3.89wt.%, so that the influence of the preparation of the porous layer in the step 2 on the service life of the bonding strength of the electrode can be obviously obtained.

Electrocatalytic reduction CO2 performance test

The carbon dioxide reduction reactor device selects an H-shaped double-air-chamber electrochemical cell, takes a copper-based composite material as a working electrode, a Pt sheet as a counter electrode and an Ag/AgCl electrode as a reference electrode to form a three-electrode system, a Nafion membrane is used as a diaphragm between the working electrode and the counter electrode/reference electrode, only protons are allowed to pass through, gas communication is cut off, the reaction temperature is normal temperature and normal pressure, and CO is carried out₂High purity (99.99%) CO was used prior to reduction₂Continuously bubbling at the flow rate of 20ml/min to clean the electrolyte for 30 minutes to remove other gases in the electrolyte to achieve CO₂Saturated, at-1.8V vs Ag/AgCl electrolysis voltage, 40min electrolysis time, with different moles of potassium bromide for product analysis, as shown in Table 1 below.

Table 1 product distribution and selectivity at different KBr concentrations.

From the above table 1, it can be seen that the copper-based composite material of the present invention has the best selectivity for ethylene and the highest faradaic efficiency.

Table 2 faradaic efficiency table of copper-based composites at different voltages.

The faradaic efficiency of S-3 ethylene was tested at 2.5MKBr under different voltage valorization conditions, as shown in table 2, with increasing voltage, FE increased slowly and then decreased rapidly, reaching a peak at-1.8V, with FE value of 64.1%.

Table 3 table of CO conversion table for copper-based composites at different times.

From the above table, the conversion rate of the copper-based composite material is obviously improved along with time, namely the copper-based composite material has excellent stability and carbon deposition resistance.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. Electrocatalytic reduction of CO by copper-based composite material₂The copper-based composite material is characterized by being prepared by the following steps:

(1) pretreating the copper-based alloy;

(2) taking a copper-containing solution as an electrolyte, taking a copper-based alloy as a cathode, and carrying out electrochemical deposition reduction under extremely high negative bias;

(3) chemically reducing the copper nanowire seed crystal at high temperature;

(4) carrying out hydrothermal treatment to obtain a thorn-shaped copper-based composite material;

(5) oxidizing;

wherein the oxidizing solution used in the step (5) is a mixed solution of ammonia water and copper carbonate,

2. The copper-based composite material according to claim 1, which is used in electrocatalytic reduction of CO₂In (1) shouldThe copper-based alloy is characterized in that the copper-based alloy is a copper-nickel cupronickel alloy, and the shape is a rod or a plate.

3. The copper-based composite material according to claim 1, which is used in electrocatalytic reduction of CO₂The method is characterized in that the grinding is as follows: and sanding by using 200#, 600#, and 1200# sandpaper in sequence.

4. The copper-based composite material according to claim 1, which is used in electrocatalytic reduction of CO₂The use of (1), characterized in that the degreasing is 15g/L Na₂CO₃、 10g/L Na₃PO₄ ^.12H₂O、10 g/L Na₂SiO₃At a temperature of 50 deg.C^oC, time 2 min.

5. The copper-based composite material according to claim 1, which is used in electrocatalytic reduction of CO₂Characterized in that the copper-containing electrolyte: 140-150g/L CuSO₄ ^.5H₂O；30-35g/L H₂SO₄；40-45g/L Cl^-(ii) a 0.5-1g/L APEO; temperature is 25-30 DEG C^oC; the direct current constant voltage is-13V, and the time is 5s-10 s.

6. The copper-based composite material according to claim 1, which is used in electrocatalytic reduction of CO₂Characterized in that the solution used in the high-temperature chemical reduction of step (3): 3-5M anhydrous copper acetate in 300-350 deg.C^oAnd C, keeping the state of non-sealing for 15-20 min.

7. The copper-based composite material according to claim 1, which is used in electrocatalytic reduction of CO₂Characterized in that the hydrothermal temperature in the step (4) is 110-^oC, the time is 12-24 h.

8. The copper-based composite material according to claim 1, which is used in electrocatalytic reduction of CO₂Characterized in that said step (3)And (4) the reaction kettle in the step (4) is a stainless steel lining-free hydrothermal reaction kettle, and before the step (4), nitrogen is used for evacuating air in the reaction kettle in the step (3).

9. The copper-based composite material according to claim 1, which is used in electrocatalytic reduction of CO₂The application of (5) is characterized in that the concentration of the ammonia water in the step (5) is 100-^oC。