WO2023082409A1 - Copper-based catalyst and electrode for electrochemical catalytic carbon dioxide reduction and energy storage, preparation method therefor and application thereof - Google Patents

Abstract

A copper-based catalyst for electrochemical catalytic carbon dioxide reduction and energy storage driven by new energy electrical energy, which is prepared by copolymerizing copper nanoparticles and a modified polymer. The modified polymer is a polymer having a proton conductive side chain and an electronic conductive main chain. According to the catalyst, a brand-new modified group is used to modify the copper-based catalyst as an electrochemical catalytic electrode, so that the catalytic efficiency and Faraday efficiency of an existing copper-based catalyst are improved, the loss of an input energy is reduced, and efficient storage and carbon neutralization of the electrical energy are achieved.

Description

Electrochemical catalytic carbon dioxide reduction energy storage copper-based catalyst, 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 technique

General Secretary Xi Jinping proposed at the general debate of the 75th session of the United Nations General Assembly that "China will increase its nationally determined contributions and adopt more powerful policies and measures. neutralize". Therefore, doing a good job in carbon peaking and carbon neutrality is my country's national policy to deal with climate change, and it is an internal demand for my country's economic structure transformation and upgrading and implementation of sustainable development. Promoting carbon peaking and achieving carbon neutrality is the key to further fighting the tough battle against pollution and promoting high-quality development.

In terms of sources of carbon emissions, carbon dioxide emissions from energy consumption account for nearly 90% of my country's total carbon dioxide emissions and nearly 80% of net greenhouse gas emissions. Therefore, the green transition in the energy sector is crucial to the realization of the goal of carbon neutrality. In the field of energy, carbon emissions from the power sector account for about 40%, and the proportion is increasing year by year. Under the general trend of electrification, the zero-carbon development of the power system will be a key to achieving the "30·60 goal". Therefore, in December 2020, China further promised at the Climate Ambition Summit: by 2030, non-fossil energy will account for about 25% of China's primary energy consumption, and the total installed capacity of wind power and solar power will reach more than 1.2 billion kilowatts. As a key technology supporting the development of renewable energy, energy storage will usher in a new stage of leapfrog development.

Electrochemical catalytic processes are considered to be a reliable solution for the efficient integration of renewable resources such as wind and solar energy into the current carbon-neutral energy mix. The scheme aims to use electrocatalysts combined with carbon dioxide, activated by electrical energy, to reduce carbon dioxide into fuels such as methanol, ethanol and methane, and store these fuels until they are reconverted during periods of high power consumption. Compared with methanol and ethanol, it is easier to transport, has higher energy storage density per unit mass, and is more compatible with existing fuel storage equipment. An important carrier fuel and widely used.

There have been a large number of studies on the use of electrocatalysts for the reduction of carbon dioxide to produce methane for electrical energy storage. Nickel-based catalysts are widely used in the reduction of carbon dioxide to methane due to their low cost and easy availability. However, even at low temperatures, nickel catalysts may be deactivated due to sintering of nickel particles, formation of mobile nickel carbonylenes, or formation of carbon deposits. In addition, active metals Rh, Co, Fe, etc. have also been reported as effective catalysts for carbon dioxide reduction to methane, but the high cost of these catalysts limits their industrial applications.

Compared with the above-mentioned catalysts, copper-based catalysts are cheaper and are the most effective catalysts for reducing carbon dioxide to hydrocarbons. They have advantages in improving the selectivity of carbon dioxide conversion products, and are also the most effective for carbon dioxide methanation and industrialized electric energy storage. means. By modifying the copper-based catalyst with chemical small molecules, not only the reaction rate can be increased, but also the formation of methane on the copper-based surface can be further promoted by suppressing the hydrogen evolution reaction.

However, for the use of copper-based catalysts, the current research has encountered difficulties. First, the key parameters of energy storage efficiency in the process of electrochemical reduction of carbon dioxide energy storage, that is, the Faraday efficiency is insufficient, and the energy input loss is large; the second is the lack of energy storage products after reduction. Specificity, it is difficult to form a homogeneous product with high purity. In addition, because the traditional chemical small molecule is used to modify the copper electrode, although the conversion efficiency of carbon dioxide can be increased, the copper catalyst is prone to be desorbed from the electrode during use, and then removed with the liquid flow in the electrolytic cell, resulting in an effective Less catalyst and lower Faradaic efficiency.

Technical solutions

The technical problem to be solved by the present invention is to provide a catalyst for electrochemical catalytic carbon dioxide reduction energy storage driven by new energy and electric energy, using a brand-new modification group to modify the copper-based catalyst as an electrochemical catalytic electrode to improve the catalytic efficiency of the existing copper-based catalyst And Faraday efficiency, reduce the loss of input energy, and realize the efficient storage of electric energy.

Based on this, the present invention provides a copper-based catalyst for electrochemically catalytic carbon dioxide reduction energy storage driven by new energy electric energy. The copper-based catalyst is composed of copper nanoparticles and a modified polymer, and the modified polymer is proton conductive Polymers with side chains and electronically conductive backbones.

Wherein, the electronically conductive main chain has more than one conjugated group, and the conjugated group may be an alkenyl group or an aromatic conjugated group.

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

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

The present invention also provides an electrochemical catalytic carbon dioxide reduction energy storage electrode driven by new energy, which includes: an electrode substrate and the above-mentioned copper-based catalyst, and the copper-based catalyst can be prepared as a coating and coated on the electrode substrate .

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

The present invention also provides a method for preparing an electrochemical electrode using the above-mentioned copper-based catalyst, which includes: preparing the electrochemical catalytic electrode by using an in-situ co-deposition method or a coating method.

Wherein, the in-situ co-deposition method further specifically includes: the first step, the preparation of an electroplating solution, the electroplating solution includes a CuSO ₄ solution, the above-mentioned modified polymer, Na ₂ SO ₄ and H ₂ SO ₄ , and the above-mentioned components are prepared according to proportions mixed together;

In the second step, the electrode base material is put into the above-mentioned electroplating solution, and electroplating is performed by an electroplating method.

Wherein, the concentration of the modifying polymer is preferably 1 μM-200 μM.

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

Beneficial effect

The invention adopts a brand-new modification group to modify the copper-based catalyst as an electrochemical catalytic electrode, uses new energy to drive electrochemical catalytic carbon dioxide reduction energy storage, improves the catalytic efficiency and Faraday efficiency of the existing copper-based catalyst, reduces the loss of input energy, and realizes electric energy efficient storage.

Description of drawings

The faradaic efficiency comparison of carbon dioxide electroreduction of the polymer-Cu modified electrode obtained in different embodiments of Fig. 1;

The local pH value of the electrode surface of Fig. 2 different embodiment catalytic cathodes;

Fig. 3 Comparison of methane Faradaic efficiency of different modified polymers.

Detailed ways

In the present invention, the copper-based catalyst is modified by a polymer modification group with a special structure, and the hydrophilicity and hydrophobicity of the polymer side chain affect the protonation process of the _CO2 reduction reaction and the diffusion process of _CO2 on the electrode surface, both It will further regulate the efficiency of the reaction and the product.

First, the chemical properties of the polymer polymer side chains provided by the present invention regulate the reduction of _CO2 on the Cu surface, since the polymers used contain proton-conducting side chains, such as those containing sulfonic acid groups or containing phosphoric acid groups The side chain can effectively increase the concentration of CO radicals on the surface of the Cu electrode and the surface pH value in the reaction system. While regulating the catalytic activity, it also significantly regulates the formation of products, making the entire reaction easy to form methane.

In addition, the electronically conductive main chain of the polymer provided by the present invention has more than one conjugated group, and the conjugated group can be an alkenyl group, an aromatic conjugated group, etc., which can significantly reduce the electrode interface impedance and improve the conversion into methane Faraday efficiency and catalytic current density (catalytic efficiency).

Based on the above principles, the present invention provides a copper-based catalyst for electrochemically catalytic carbon dioxide reduction energy storage driven by new energy. The copper-based catalyst is obtained by electroplating copper nanoparticles and modified polymers. The modified polymer The polymer is a polymer with a proton-conducting side chain and an electron-conducting main chain.

The electronically conductive main chain has more than one conjugated group, and the conjugated group may be an alkenyl group or an aromatic conjugated group, more preferably a butadienyl group.

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

The polymer is further preferably polystyrenesulfonic acid (PSS), polybutadienesulfonic acid, polybutadienesulfonate, polyaniline with camphorsulfonic acid as a dopant.

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

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

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

The coating thickness is preferably 2 μm-25 μm, more preferably 8 μm-20 μm.

The copper-based catalyst can also directly modify the above-mentioned polymer on the copper electrode to prepare an electrochemical catalytic electrode.

The present invention adopts an in-situ co-deposition method or a coating method to prepare an electrochemical catalytic electrode, and the in-situ co-deposition method is more preferred. Further preferably, the in-situ co-electrodeposition method can be used to deposit the polymer on the copper electrode, which can keep the polymer molecules on the surface of the electrode and avoid the problem of desorption from the copper electrode.

The present invention also provides a preparation method for the above-mentioned electrochemical catalytic electrode, which adopts an in-situ co-deposition method, specifically comprising:

The first step is the preparation of the electroplating solution, the electroplating solution includes CuSO ₄ solution, the above-mentioned modified polymer, Na ₂ SO ₄ , H ₂ SO ₄ , and the above-mentioned components are mixed together in proportion;

In the second step, the electrode base material is put into the above-mentioned electroplating solution, and electroplating is performed by an electroplating method.

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

The concentration of the modifying polymer is preferably 1 μM-200 μM, more preferably 10 μM-100 μM, even more preferably 10 μM-20 μM.

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

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

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

The present invention also provides a new energy-driven electrochemical catalytic carbon dioxide reduction energy storage system, which includes: the above-mentioned electrochemical catalytic electrode as a cathode, an electrolyte, and an anode.

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

The electrolyte solution can be KHCO ₃ , NaHCO _{3 ,} etc., and the concentration is between 0.05M-2M, more preferably between 0.05M-1M.

The present invention also provides a new energy-driven electrochemical catalytic carbon dioxide reduction energy storage method, which includes:

The first step is to pass the carbon dioxide gas source into the system electrolyte until saturated;

The second step is to use new energy to provide electricity to the above-mentioned carbon dioxide reduction energy storage system for electrochemical catalytic reaction;

The third step is to export and store the generated methane fuel for subsequent energy use.

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 implementation of the present invention will be described in detail below with examples and accompanying drawings, so as to fully understand and implement the process of how to apply technical means to solve technical problems and achieve technical effects in the present invention.

Preparation of modified copper electrodes

Pour different concentrations of CuSO ₄ solutions in Table 1, different concentrations and types of small molecule polymers, different concentrations of Na ₂ SO ₄ and different concentrations of H ₂ SO ₄ into the electroplating container, using the in-situ co-deposition method, stirring Mix well to obtain different plating solutions.

The graphite electrode substrate was put into the above electroplating solution, and electroplating was performed with a deposition current density of -3mA/cm ² , a total deposition electricity of 2.5C/cm ² , and a prepared catalyst layer with a thickness of 12 μM.

Table 1 Electrode Preparation Reaction System with Different Proportions

The molar ratio of polyaniline with camphorsulfonic acid as a dopant: aniline monomer: camphorsulfonic acid is 1:8.

Influence of Faradaic Efficiency of Electrochemical Energy Conversion of Carbon Dioxide Electrocatalytic Reduction into Methane and Catalytic Efficiency of Carbon Dioxide Reduction

Faraday efficiency refers to the percentage of the actual product and the amount of the theoretical product. The amount of the theoretical product is the reduction electrons generated by the catalytic electrode using electric energy. The number of electron transfers in the catalytic reaction is calculated, which is theoretically used to reduce CO ₂ The total amount of product that can be produced. The content of the product was detected by gas chromatography.

The modified copper electrode prepared in the above example is used as the cathode, the inert metal platinum electrode is used as the anode, and the 0.1M sodium bicarbonate solution saturated with _CO2 is used as the electrolyte to construct a carbon dioxide reduction energy storage system, and the _CO2 gas source is passed into The system electrolyte is saturated to saturation, and the solar power supply system is used for power supply to carry out the electrochemical catalytic reaction. 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 methane faradaic efficiency and catalytic current density in different embodiments

It can be seen from Figure 1 and Table 2 that the co-deposition of different polymers and Cu particles in each example significantly played a role in regulating the catalytic product. As can be seen from Figure 2 and below, under the same conditions and the same potential, the catalytic electrode (Example 4) modified by copolymerization of 20 μM polybutadiene sulfonic acid and Cu (Example 4) at -0.9V, catalytic methanation reached the highest Faradaic efficiency of 94 %. Among its major by-products, the Faradaic efficiency of CO is less than 3%, and that of ethylene is less than 2%. Hydrogen evolution was suppressed on the Cu-polymer catalyst, and the faradaic efficiency of hydrogen evolution was <5% over the entire potential range, which may be due to the higher surface pH of this catalyst relative to other catalysts, and the higher Proton transfer properties. Although the polymers adopted in each embodiment are all conjugated main chains, compared with other embodiments, the polybutadiene sulfonic acid of embodiment 3 or 4 has reduced the steric position of the side chain because there is no benzene ring. resistance, so that the sulfonic acid density of the microenvironment of the copper catalytic site of the polymer-copper composite is higher and the proton conductivity is stronger, so after _{the 2} -fold reduction of CO to produce the CO* intermediate, there are enough protons to provide further promotion methane production.

The difficulty of protonation in the microenvironment of different polymers can be achieved by electrochemical in situ Raman characterization combined with in situ electrochemical pH probes. Spike potential -0.82V acquisition data calculation. In each embodiment, in the pH 6.8 _CO2 saturated sodium bicarbonate electrolyte, the local pH of different polymer modified electrodes changes in the reaction onset potential (OCP) and the reaction peak current potential value (-0.82V) as follows As shown in Figure 2, due to the existence of different proton donors and conductive side chains (sulfonic acid groups) in each embodiment, the initial local pH of the electrode surface is all less than the pH of the electrolyte, but as the catalytic reduction reaction progresses, the The CO* radicals generated on the electrode surface continuously obtain protons from the environment, thereby generating methane, and the local pH will continue to rise, while in Examples 3 and 4, due to the higher local sulfonic acid group density, there is a stronger The proton-providing ability and proton-conducting ability, so the increase of its pH is smaller than that of other examples, maintaining a microenvironment that is conducive to the electrocatalytic production of methane by CO ₂ .

Effects of Faradaic Efficiency and Catalytic Efficiency of Carbon Dioxide Reduction on Copper Electrodes Prepared by Different Modified Polymers

Using the same preparation method as in Example 1, the modified polymer used in Table 3 was used to replace the sodium polybutadiene sulfonate in Example 4, and the rest remained unchanged to prepare different electrolytes.

Table 3 Electrolyte prepared by different modified polymers

Table 4 Comparison of methane faradaic efficiency and catalytic current density of different modified polymers

The results are shown in Figure 3 and Table 4. Compared with the modification using sodium polybutadiene sulfonate in Example 4, the electrode of Comparative Example 1 does not adopt any modification of the electrode, and the polymer used in Comparative Example 2 does not have the The conjugated conductive main chain of the polymer and the proton-conductive side chain, the methane Faraday efficiency of Comparative Example 1 and Comparative Example 2 are significantly reduced, modified with polyamine, more converted into other hydrocarbons, without any modification , staying mainly in the conversion to CO products.

Effects of different polymer modification layer thicknesses on methane faradaic efficiency and carbon dioxide reduction catalytic efficiency

Using the electrode preparation reaction system described in Example 4, using the same preparation method to prepare copper-based catalyst-coated electrodes with different thicknesses, and performing electrochemical catalytic reduction to prepare methane, the results are shown in Table 3.

Table 5 Comparison of methane faradaic efficiency and catalytic current density of coatings with different thicknesses

Coating Thickness (μM)	Faradaic efficiency of methane (%)	Maximum catalytic current density (mA/cm 2 )
2	11	12
5	twenty three	33
8	59	132
12	94	488
16	82	411
20	55	121
25	15	18

It can be seen from Table 5 that the faradaic efficiency of methane conversion is significantly higher than that of other coating thicknesses when the thickness of the co-deposited copper-based catalyst layer is 12 μM-16 μM, and the maximum catalytic current density is also significantly higher than that of other layer thicknesses. In the case of the electrode, it is reflected that within this layer thickness range, the electrocatalytic carbon dioxide conversion efficiency is the highest, and it is easier to form methane.

All of the above-mentioned primary implementations of this intellectual property rights are not intended to limit other forms of implementations of this new product and/or new method. Those skilled in the art will, with this important information, modify the above to achieve a similar implementation. However, all modifications or alterations to the new product based on the present invention belong to reserved rights.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention to other forms. Any skilled person who is familiar with this profession may use the technical content disclosed above to change or modify the equivalent of equivalent changes. Example. However, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still belong to the protection scope of the technical solution of the present invention.

Claims (10)

1. A copper-based catalyst for electrochemically catalytic carbon dioxide reduction energy storage driven by new energy and electric energy, characterized in that: the copper-based catalyst is composed of copper nanoparticles and a modified polymer, and the modified polymer has a proton-conductive side chain, a polymer with an electronically conductive backbone.
2. The copper-based catalyst for electrochemically catalytic carbon dioxide reduction energy storage driven by new energy electric energy according to claim 1, characterized in that: the electronically conductive main chain has more than one conjugated group, and the conjugated group The group can be an alkenyl group, an aromatic conjugated group.
3. The copper-based catalyst for electrochemically catalytic carbon dioxide reduction energy storage driven by new energy electric energy as claimed in claim 1 or 2 is characterized in that: the proton-conducting side chain is preferably a side chain containing a sulfonic acid group, containing phosphoric acid base side chain.
4. The copper-based catalyst for electrochemically catalytic carbon dioxide reduction energy storage driven by new energy electric energy as claimed in claim 1 or 2 is characterized in that: the polymer is further polystyrene sulfonic acid (PSS), polybutadiene Sulfonic acid, polybutadiene sulfonate polyaniline with camphorsulfonic acid as dopant.
5. An electrochemical catalytic carbon dioxide reduction energy storage electrode for driving by new energy electric energy, characterized in that it comprises: an electrode substrate and the copper-based catalyst according to any one of claims 1 to 4, and the copper-based catalyst can be prepared The coating is applied to the electrode substrate.
6. The electrochemical catalytic carbon dioxide reduction energy storage electrode for driving by new energy electric energy according to claim 5, characterized in that: the thickness of the coating formed by the copper-based catalyst is 2 μm-25 μm, more preferably 8 μm-20 μm.
7. The method for preparing an electrochemical electrode using the copper-based catalyst described in any one of claims 1 to 4 is characterized in that: the electrochemical catalytic electrode is prepared by an in-situ co-deposition method or a coating method.
8. The method for preparing an electrochemical electrode as claimed in claim 7, characterized in that: said in-situ co-deposition method further specifically includes,

   The first step is the preparation of electroplating solution. The electroplating solution includes CuSO ₄ solution, the above-mentioned modified polymer, Na ₂ SO ₄ and H ₂ SO ₄ , and the above-mentioned components are mixed together in proportion;

   In the second step, the electrode base material is put into the above-mentioned electroplating solution, and electroplating is performed by an electroplating method.
9. The method for preparing an electrochemical electrode according to claim 7 or 8, characterized in that: the concentration of the modifying polymer is 1 μM-200 μM.
10. The application of the reduction energy storage electrode described in claim 5 or 6 in realizing carbon dioxide reduction energy storage.

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