CN113957480B

CN113957480B - Copper-based catalyst for electrochemical catalysis of carbon dioxide reduction and energy storage, electrode, preparation method and application thereof

Info

Publication number: CN113957480B
Application number: CN202111323665.2A
Authority: CN
Inventors: 夏霖
Original assignee: Shenzhen Institute of Advanced Technology of CAS
Current assignee: Shenzhen Zhongkeling Carbon Biotechnology Co ltd
Priority date: 2021-11-09
Filing date: 2021-11-09
Publication date: 2022-11-22
Anticipated expiration: 2041-11-09
Also published as: CN113957480A; WO2023082409A1

Abstract

The invention provides a copper-based catalyst for electrochemical catalysis of carbon dioxide reduction and energy storage driven by new energy electric energy, which is prepared by copolymerization of copper nanoparticles and a modified polymer, wherein the modified polymer is a polymer with a proton-conducting side chain and an electronic-conducting main chain. The catalyst adopts a brand-new modifying group modified copper-based catalyst as an electrochemical catalytic electrode, improves the catalytic efficiency and Faraday efficiency of the existing copper-based catalyst, reduces the loss of input energy, and realizes the high-efficiency storage and carbon neutralization of electric energy.

Description

Copper-based catalyst for electrochemical catalysis of carbon dioxide reduction and energy storage, electrode, preparation method and application thereof

Technical Field

The invention relates to the technical field of electric energy storage, in particular to a carbon dioxide reduction energy storage method driven by new energy electric energy.

Background

From the carbon emission source, the emission of energy consumption carbon dioxide accounts for nearly nine times of the total carbon dioxide emission in China and nearly eight times of the net emission of greenhouse gases. Green color transformation in the energy field is therefore crucial for the achievement of the carbon neutralization goal. In the field of energy, the carbon emission of the power department is about four times, and the carbon emission rate is increased year by year. Under the great trend of electrification, the zero-carbon development of the power system is a great key for achieving the 30-60 target. Therefore, in 12 months in 2020, china makes further commitments at the climatic peak of mind: the consumption ratio of Chinese non-fossil energy to primary energy in 2030 years reaches about 25%, and the total installed capacity of wind power generation and solar power generation reaches more than 12 hundred million kilowatts. As a key technology for supporting the development of renewable energy, energy storage will begin to develop in a new step-by-step manner.

Electrochemical catalytic processes are considered to be a reliable solution for the efficient integration of renewable resources like wind and solar energy into current carbon and energy combinations. The scheme aims to combine an electrocatalyst with carbon dioxide, reduce the carbon dioxide through electric energy activation, convert the carbon dioxide into fuels such as methanol, ethanol and methane, and store the obtained fuels until the fuels are implemented in a high power consumption period, and convert the fuels into electric energy again, wherein the methane is a main component of Synthetic Natural Gas (SNG), and compared with methanol and ethanol, the synthetic natural gas is easier to transport, has higher energy storage density per unit mass and higher compatibility with the existing fuel storage equipment, and is an important carrier fuel for electric energy storage, so that the synthetic natural gas is widely applied.

There have been a lot of studies on the preparation of methane by using electrocatalysts for carbon dioxide reduction to realize electric energy storage. Nickel-based catalysts are widely used for the reduction of carbon dioxide to produce methane due to their low cost and ready availability. However, even at low temperatures, nickel catalysts may deactivate due to sintering of nickel particles, formation of mobile nickel carbonylidene groups, or formation of carbon deposits. In addition, active metals Rh, co, fe, etc. have also been reported as effective catalysts for the reduction of carbon dioxide to produce methane, however, these catalysts are costly and limit their industrial application.

Compared with the catalyst, the copper-based catalyst has lower cost, is the most effective catalyst for reducing carbon dioxide into hydrocarbon, has the advantage of improving the selectivity of the carbon dioxide conversion product, and is the most effective means for methanation of carbon dioxide and realization of industrial electric energy storage. By using the chemical micromolecule modified copper-based catalyst, the reaction rate can be improved, and the formation of methane on the surface of the copper-based catalyst is further promoted by inhibiting the hydrogen evolution reaction.

However, for the copper-based catalyst, the current research has the problems that the key parameter of the energy storage efficiency in the energy storage process of electrochemical reduction of carbon dioxide, namely, the faradaic efficiency is insufficient, and the energy input loss is large; secondly, the reduced energy storage product lacks specificity and is difficult to form a high-purity uniform product. In addition, since the copper electrode is modified with conventional chemical small molecules, although the conversion efficiency of carbon dioxide can be increased, desorption of the copper catalyst from the electrode during use easily occurs and is then removed with the flow of liquid in the electrolytic cell, resulting in a decrease in effective catalyst and a low faradaic efficiency.

Technical scheme

The technical problem to be solved by the invention is to provide a catalyst for electrochemical catalytic carbon dioxide reduction and energy storage driven by new energy electric energy, wherein a brand-new modifying group modified copper-based catalyst is used as an electrochemical catalytic electrode, so that the catalytic efficiency and Faraday efficiency of the existing copper-based catalyst are improved, the loss of input energy is reduced, and the efficient storage of electric energy is realized.

Based on the above, the invention provides a copper-based catalyst for electrochemical catalysis of carbon dioxide reduction energy storage driven by new energy electric energy, wherein the copper-based catalyst comprises copper nanoparticles and a modified polymer, and the modified polymer is a polymer with a proton-conducting side chain and an electron-conducting main chain.

Wherein the electron conductive main chain has more than one conjugated group, and the conjugated group can be alkenyl or aromatic conjugated group.

Among them, the proton conductive side chain is preferably a side chain containing a sulfonic acid group, a side chain containing a phosphoric acid group.

Wherein the polymer is further polystyrene sulfonic acid (PSS), polybutadiene sulfonic acid, polyaniline with camphorsulfonic acid as dopant.

The invention also provides an electrochemical catalytic carbon dioxide reduction energy storage electrode for new energy drive, comprising: an electrode substrate and the above-mentioned copper-based catalyst, which can be prepared as a coating applied to the electrode substrate.

The thickness of the coating formed by the copper-based catalyst is 2 μm to 25 μm, and more preferably 8 μm to 20 μm.

The invention also provides a method for preparing an electrochemical electrode by adopting the copper-based catalyst, which comprises the following steps: and preparing the electrochemical catalytic electrode by adopting an in-situ codeposition method or a coating method.

Wherein, the in-situ codeposition method further comprises the following steps: first, preparation of an electroplating bath comprising CuSO ₄ Solution, the modifying polymer and Na ₂ SO ₄ And H ₂ SO ₄ Mixing the above components together in proportion;

and secondly, putting the electrode base material into the electroplating solution, and electroplating by adopting an electroplating method.

Wherein the concentration of the modifying polymer is preferably 1. Mu.M-200. Mu.M.

The invention also provides application of the reduction energy storage electrode in realizing carbon dioxide reduction energy storage.

Advantageous effects

The invention adopts a brand-new modifying group modified copper-based catalyst as an electrochemical catalytic electrode, utilizes new energy to drive electrochemical catalysis carbon dioxide to reduce and store energy, improves the catalytic efficiency and Faraday efficiency of the existing copper-based catalyst, reduces the loss of input energy, and realizes the high-efficiency storage of electric energy.

Drawings

FIG. 1 shows a comparison of faradaic efficiencies of carbon dioxide electroreduction of polymer-Cu modified electrodes obtained in different examples;

FIG. 2 shows the local pH values of the electrode surface of the catalytic cathode in different embodiments;

FIG. 3 shows a comparison of the faradaic efficiencies of different modified polymers for methane.

Detailed Description

In the invention, the copper-based catalyst is modified by a polymer modifying group with a special structure, and the hydrophilicity and the hydrophobicity of a polymer side chain influence CO ₂ Protonation process of reduction reaction, and CO ₂ The diffusion process at the electrode surface, both of which can further regulate the efficiency of the reaction and the product.

First, the chemical properties of the polymer side chains provided by the present invention are CO ₂ Due to the regulation and control effect of the reduction on the Cu surface, the adopted polymer contains a proton conducting side chain, such as a side chain containing a sulfonic group or a side chain containing a phosphoric group, the concentration of CO free radicals on the surface of the Cu electrode in a reaction system and the pH value of the surface can be effectively improved, the catalytic activity is regulated and controlled, the formation of a product is also remarkably regulated and controlled, and the whole reaction is easy to form methane.

In addition, the polymer electronic conductivity main chain provided by the invention has more than one conjugated group, and the conjugated group can be alkenyl, aromatic conjugated group and the like, so that the interfacial impedance of the electrode can be obviously reduced, and the Faraday efficiency and the catalytic current density (catalytic efficiency) for converting into methane can be improved.

Based on the principle, the invention provides a copper-based catalyst for electrochemical catalysis carbon dioxide reduction energy storage driven by new energy, the copper-based catalyst is obtained by electroplating copper nanoparticles and a modified polymer, and the modified polymer is a polymer with a proton conductive side chain and an electron conductive main chain.

The electron-conductive main chain has one or more conjugated groups, and the conjugated group may be an alkenyl group or an aromatic conjugated group, and a butadiene group is more preferable.

The proton conductive side chain is preferably a side chain containing a sulfonic acid group, a side chain containing a phosphoric acid group.

The polymer is more preferably polystyrene sulfonic acid (PSS), polybutadiene sulfonic acid, polybutylene sulfonate, polyaniline with camphor sulfonic acid as a dopant.

The copper-based catalyst can be prepared into a coating to be coated on an electrode substrate to prepare an electrochemical catalytic electrode, and the electrode substrate can be a carbon material electrode, a carbon material composite electrode, a noble metal electrode, a stainless steel electrode, a copper electrode, an iron electrode and the like.

The carbon material electrode may further be a graphite electrode, a carbon fiber electrode, a graphene electrode, a carbon nanotube electrode, a diamond electrode, or the like.

The noble metal electrode may further be selected from gold, silver, platinum, and the like.

The thickness of the coating layer is preferably 2 μm to 25 μm, and more preferably 8 μm to 20 μm.

The copper-based catalyst can also be used for directly modifying the polymer on a copper electrode to prepare an electrochemical catalytic electrode.

The electrochemical catalytic electrode is prepared by adopting an in-situ co-deposition method or a coating method, and the in-situ co-deposition method is further preferred. Further preferably, an in-situ co-electrodeposition method is adopted, which can deposit the polymer on the copper electrode, can realize that polymer molecules are kept on the surface of the electrode, and avoids the problem of desorption from the copper electrode.

The invention also provides a preparation method of the electrochemical catalytic electrode, which adopts an in-situ co-deposition method and specifically comprises the following steps:

first, preparation of an electroplating bath, the bath comprising CuSO ₄ Solution, the modifying polymer and Na ₂ SO ₄ 、H ₂ SO ₄ Mixing the above components together in proportion;

and secondly, putting the electrode substrate into the electroplating solution, and electroplating by adopting an electroplating method.

The CuSO ₄ The concentration of the solution is preferably 1mM-10mM, more preferably 1mM-5mM.

The concentration of the modifying polymer is preferably 1. Mu.M to 200. Mu.M, more preferably 10. Mu.M to 100. Mu.M, and still more preferably 10. Mu.M to 20. Mu.M.

The Na is ₂ SO ₄ The concentration of the solution is preferably 0.01M to 0.2M, more preferably 0.05M to 0.1M.

Said H ₂ SO ₄ The concentration of the solution is preferably 0.1M to 1M, and more preferably 0.3M to 0.5M.

The current density in the second step is preferably (-0.5 mA/cm) ² )-(-10mA/cm ² ) Further, it is more preferably (-2 mA/cm) ² )-(-6mA/cm ² )。

The invention also provides a new energy driven electrochemical catalytic carbon dioxide reduction energy storage system, comprising: the electrochemical catalytic electrode, the electrolyte and the anode are used as cathodes.

The anode may be an inert metal electrode or a carbon electrode.

The electrolyte may be KHCO ₃ 、NaHCO ₃ The concentration is, for example, 0.05M to 2M, more preferably 0.05M to 1M.

The invention also provides a new energy driven electrochemical catalytic carbon dioxide reduction energy storage method, which comprises the following steps:

firstly, introducing a carbon dioxide gas source into system electrolyte until the carbon dioxide gas source is saturated;

step two, new energy is adopted to provide power to the carbon dioxide reduction energy storage system for electrochemical catalytic reaction;

and thirdly, leading the generated methane fuel out for storage so as to be used for subsequent energy supply.

In the second step, the pH value of the electrolyte is 6.2-6.8, and the reaction temperature is room temperature.

The new energy can be photovoltaic new energy, wind energy and the like.

The following embodiments of the present invention will be described in detail with reference to the accompanying drawings and examples, so that how to apply the technical means to solve the technical problems and achieve the technical effects can be fully understood and implemented.

Preparation of modified copper electrode

Different concentrations of CuSO in Table 1 ₄ Solution, small molecule polymer with different concentrations and types, na with different concentrations ₂ SO ₄ And H of different concentrations ₂ SO ₄ Pouring into an electroplating container, and stirring and mixing uniformly by adopting an in-situ codeposition method to obtain different electroplating solutions.

Placing the graphite electrode substrate in the electroplating solution, and electroplating with a deposition current density of-3 mA/cm ² The total deposited electricity quantity is 2.5C/cm ² The prepared catalyst layer was thick 12. Mu.M.

TABLE 1 reaction system for preparing electrodes with different proportions

The molar ratio of polyaniline, aniline monomer and camphorsulfonic acid which take camphorsulfonic acid as a doping agent is 1: 8.

Faraday efficiency of conversion of electric energy into chemical energy and influence of carbon dioxide reduction catalysis efficiency on conversion of carbon dioxide into methane by electrocatalytic reduction

The Faraday efficiency is the percentage of the amount of actual product and theoretical product, i.e., the amount of reduction electrons generated by the catalytic electrode using electric energy, and the electron transfer number of the catalytic reaction is calculated, and theoretically all the electrons are used for reductionCO ₂ The total amount of product that can be produced. The content of the product is obtained by gas chromatography detection.

The modified copper electrode prepared in the above example was used as the cathode, the inert metal platinum electrode was used as the anode, and the concentration was CO ₂ Saturated 0.1M sodium bicarbonate solution is used as electrolyte to construct a carbon dioxide reduction energy storage system, and CO is reduced ₂ And introducing a gas source into the electrolyte of the system until the gas source is saturated, supplying power by adopting a solar power supply system, carrying out electrochemical catalytic reaction, wherein the working voltage applied to the cathode is-0.82V (vs silver/silver chloride electrode), the reaction temperature is room temperature, and the pH value is 6.8.

TABLE 2 comparison of the Faraday efficiencies and catalytic Current densities of methane in different examples

As shown in fig. 1 and table 2, the co-deposition of different polymers and Cu particles in each example significantly acts as a control for the catalytic products. From FIG. 2 and at the same potential, catalytic methanogenesis was achieved at-0.9V for the catalytic electrode modified with 20 μ M polybutadiene sulfonic acid copolymerized with Cu (example 4) under the same conditions with a maximum faradaic efficiency of 94%. Among the main byproducts, the faradaic efficiency of CO is lower than 3%, and the faradaic efficiency of ethylene is lower than 2%. Hydrogen evolution on Cu-polymer catalysts is inhibited, and the faradaic efficiency of hydrogen evolution is uniform over the entire potential range<5%, which may be due to the higher surface pH of the catalyst relative to other catalysts, and the higher proton transfer characteristics. Although the polymers used in the examples are conjugated main chains, compared with other examples, the polybutadiene sulfonic acid of example 3 or 4 has reduced steric hindrance of side chains due to the absence of benzene rings, so that the copper catalytic site of the polymer-copper complex has higher sulfonic acid density of microenvironment and stronger proton conductivity, and thus the polymer-copper complex has a higher CO content ₂ After the double reduction to CO intermediates, sufficient protons are available to further promote methane production.

Ease of protonation of the microenvironment of different polymersThe degree can be realized by combining electrochemical in-situ Raman characterization with an in-situ electrochemical pH probe, and data are respectively collected and calculated at a catalytic initial potential OCP and a catalytic spike potential of-0.82V by the in-situ Raman electrochemical probe. In various embodiments, CO at pH 6.8 ₂ In a saturated sodium bicarbonate electrolyte, the local pH values of different polymer modified electrodes at a reaction starting potential (OCP) and a reaction peak current potential value (-0.82V) are changed as shown in figure 2, the initial local pH values of the surfaces of the electrodes are all smaller than the pH value of the electrolyte in each embodiment due to the existence of different proton donors and conduction side chains (sulfonic acid groups), however, as the catalytic reduction reaction is carried out, CO radicals generated on the surfaces of the electrodes continuously obtain protons from the environment to generate methane, and the local pH value is continuously increased, and in examples 3 and 4, due to higher local sulfonic acid group density, the electrodes have stronger proton supplying capacity and proton conducting capacity, so the pH value is increased in a smaller range compared with other embodiments, and the increase of the pH value is favorable for CO ₂ Electrocatalysis produces a microenvironment of methane.

Influence of Faraday efficiency and carbon dioxide reduction catalysis efficiency of copper electrode prepared from different modified polymers

Different electrolytes were prepared by the same preparation method as in example 1, with the modified polymer used in table 3 replacing the sodium polybutadiene sulfonate in example 4, and the remainder being kept unchanged.

TABLE 3 electrolytes prepared from different modified polymers

TABLE 4 comparison of Faraday efficiencies and catalytic Current Density for different modified polymers

As shown in fig. 3 and table 4, the electrode of comparative example 1 did not have any modification of the electrode, and the polymer of comparative example 2 did not have the conjugated conductive main chain and the proton conductive side chain of the polymer of the present application, as compared to the modification with the polybutadiene sodium sulfonate of example 4, the methane faradaic efficiency was significantly reduced in both comparative example 1 and comparative example 2, and the modification with polyamine resulted in more conversion to other hydrocarbons, and no modification was performed, and the conversion to CO product remained dominant.

Influence of different polymer modification layer thicknesses on Faraday efficiency and carbon dioxide reduction catalysis efficiency of methane

The reaction system prepared by the electrode described in example 4 was used, copper-based catalyst coated electrodes of different thicknesses were prepared by the same preparation method, and electrochemical catalytic reduction was performed to produce methane, with the results shown in table 3.

TABLE 5 comparison of Faraday efficiencies and catalytic Current Density of coated methane of different thicknesses

Coating thickness (μ M)	Faraday efficiency of methane (%)	Maximum catalytic Current Density (mA/cm) ² )
			2	11	12
5	23	33
			8	59	132
12	94	488
			16	82	411
20	55	121
			25	15	18

From table 5, it can be seen that in the co-deposited copper-based catalyst layer thickness of 12 μ M to 16 μ M, the faradaic efficiency of methane conversion is significantly higher than that of methane of other coating thicknesses, and the maximum catalytic current density is also significantly higher than that of the electrode of other coating thicknesses, reflecting that in this layer thickness range, the electrocatalytic carbon dioxide conversion efficiency is the highest and methane is more easily formed.

All of the above mentioned intellectual property rights are not intended to be restrictive to other forms of implementing the new and/or new products. Those skilled in the art will take advantage of this important information, and the foregoing will be modified to achieve similar performance. However, all modifications or alterations are based on the new products of the invention and belong to the reserved rights.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still belong to the protection scope of the technical solution of the present invention.

Claims

1. A copper-based catalyst for electrochemical catalysis carbon dioxide reduction energy storage driven by new energy electric energy is characterized in that: the copper-based catalyst consists of copper nanoparticles and a modified polymer,

the modified polymer is polystyrene sulfonic acid, polybutadiene sulfonate and polyaniline with camphor sulfonic acid as dopant.

2. An electrochemical catalytic carbon dioxide reduction energy storage electrode for new energy electric drive, comprising: an electrode substrate and the copper-based catalyst according to claim 1, which is prepared as a coating layer applied to the electrode substrate.

3. The electrochemical catalytic carbon dioxide reduction energy storage electrode for new energy electric drive of claim 2, wherein: the thickness of the coating formed by the copper-based catalyst is 2-25 mu m.

4. A method for producing an electrochemical electrode using the copper-based catalyst according to claim 1, characterized in that: and preparing the electrochemical catalytic electrode by adopting an in-situ co-deposition method or a coating method.

5. The method of preparing an electrochemical electrode according to claim 4, wherein: the in-situ co-deposition method further specifically comprises,

first, preparation of an electroplating bath, the bath comprising CuSO ₄ Solution, the modifying polymer and Na ₂ SO ₄ And H ₂ SO ₄ Mixing the above components together in proportion;

6. The method for producing an electrochemical electrode according to claim 4 or 5, wherein: the concentration of the modifying polymer is 1-200. Mu.M.

7. Use of the reductive energy storage electrode of claim 2 or 3 for achieving carbon dioxide reductive energy storage.