GAS PHASE DIFFUSION ELECTRODE, PREPARATION METHOD, AND APPLICATION FOR ELECTROCATALYZING CO2 TO REDUCE AND PRODUCE CO

Abstract

The preparation method of a gas phase diffusion electrode for electrocatalyzing CO2 to reduce and produce CO provided by the present application comprises: mixing a conductive polymer monomer solution with a molar ratio of 100:1˜1:100 with a metal salt solution, and adding a dispersant to form a mixed solution; transferring the mixed solution to a substrate and reacting at a temperature of −30° C.-50° C. for 1-48 hours to obtain a gas phase diffusion electrode. By the method of using metal ions to self-initiate in-situ growth of conductive polymer monomers, the present application forms a metal-conductive polymer gas phase diffusion electrode. Due to the characteristics of the conductive polymer, the gas phase diffusion electrode can provide more nucleation sites, achieving similar catalytic effect while reducing use amount of metal.

Description

TECHNICAL FIELD

The present application relates to the technical field of reduction by electrocatalyzing CO₂, and in particular, to a preparation method of a gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO, a gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO, and application thereof.

BACKGROUND

With the rapid increase in atmospheric CO₂ concentration from 270 ppm in the early 19th century to 420 ppm in 2023, it is urgent to recover CO₂ waste gas. As a major CO₂ emitter, China actively fulfills its responsibilities as a major country, proposes the “dual carbon” goal, and fully promotes corporate carbon reduction.

New clean energy technologies such as solar energy, wind energy, nuclear energy, etc., are developed rapidly. Although they are not enough to replace fossil energy, obtaining renewable electricity through cheap and efficient means has become a reality. In this context, electrocatalyzing CO₂ reduction, as a clean and controllable energy conversion technology, is becoming an effective CO₂ reduction solution.

The development prospect of electrocatalyzing CO₂ reduction is very broad, but also extremely challenging. Considering from the perspective of reaction mechanism, CO₂ has strong chemical inertness, thus CO₂ reduction has great challenge in the thermodynamic aspect. On the other hand, this reaction involves a large number of basic steps, reactants, and intermediates, and also has great challenge in the kinetic aspect. Considering from the production perspective, current electrocatalyzing CO₂ reduction usually uses water as the hydrogen source. On the one hand, the solubility of CO₂ in water is very low, and on the other hand, the competition of hydrogen evolution reaction (HER) suppresses the selectivity of CO₂ reduction. Therefore, in order to promote the industrialization of electrochemical reduction of CO₂, it is necessary to design electrodes with higher conductivity, better catalytic effect, and stronger stability.

Traditional catalysts for electrocatalyzing CO₂ reduction are metal based catalysts, classified according to their composition, mainly including three types: single metal catalysts, multi metal catalysts, and modified metal composite catalysts. Among them, the selectivity of single metal catalyst products is greatly related to metal size, morphology, exposed crystal faces, etc. The selectivity of multi metal catalyst products is further greatly related to metal types, proportions, valence states, etc. These two types of catalysts have high requirements for preparation processes and are relatively expensive. The price of metal composite catalysts is relatively low, and the requirements for preparation processes are relatively low. However, the modified materials are often insulation materials, the conductivity of the catalyst is poor, requiring the addition of additional conductive carbon black.

A traditional electrode preparation method for electrocatalyzing CO₂ reduction involves first synthesizing a powdered catalyst, and then loading it onto a substrate surface through scraping coating, dripping citing, or spin coating methods. The adhesion between the catalyst and the substrate is poor, and the overall stability is poor.

SUMMARY OF THE DISCLOSURE

In view of this, aiming at the defect that conventional electrodes are low in selectivity, poor in stability, and poor conductivity for electrocatalyzing CO₂ to reduce and produce CO, it is necessary to provide a preparation method of a gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO, a gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO, and application thereof which have low cost, high selectivity, good conductivity, and excellent stability.

In order to solve the above problems, the present application adopts the following technical solutions.

A first purpose of the present application is to provide a preparation method of a gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO, comprising the following steps: mixing a conductive polymer monomer solution with a molar ratio of 100:1˜1:100 with a metal salt solution, and adding a dispersant to form a mixed solution; transferring the mixed solution to a substrate and reacting at a temperature of −30° C.-50° C. for 1-48 hours to obtain a metal-conductive polymer composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO.

In some embodiments thereof, before performing the step of mixing a conductive polymer monomer solution with a metal salt solution and adding a dispersant to form a mixed solution, the method further comprises the following step: performing pre-constant temperature treatment on the conductive polymer monomer solution and the metal salt solution at 30° C. to −18° C.

In some embodiments thereof, the conductive polymer monomer solution is prepared by the following method: adding conductive polymer monomer to an acidic solution, and mixing evenly to obtain the conductive polymer monomer solution, wherein the molar ratio of the conductive polymer monomer to the acidic solution is 50:1-1:50.

In some embodiments thereof, the conductive polymer monomer is one or more of aniline, pyrrole, thiophene, indole, pyridine, carbazole, dopamine, and p-phenylacetylene monomers.

In some embodiments thereof, the solute of the acidic solution comprises one or more of hydrochloric acid, sulfuric acid, nitric acid, formic acid, acetic acid, dodecylbenzenesulfonic acid, p-toluenesulfonic acid, and camphor sulfonic acid; the solvent of the acidic solution is one or more of water, methanol, ethanol, isopropanol, acetonitrile, ethyl acetate, chloroform, dichloromethane, acetone, N-methylpyrrolidone, dimethylformamide, and dimethyl sulfoxide.

In some embodiments thereof, the metal salt comprises one or more of silver nitrate, silver hypochlorite, silver chlorate, silver perchlorate, silver fluoride, silver acetate, silver trifluoroacetate, silver trifluoromethanesulfonate, silver methanesulfonate, silver p-toluenesulfonate, chloroauric acid, zinc nitrate, zinc hypochlorite, zinc chlorate, zinc perchlorate, palladium nitrate, palladium hypochlorite, palladium chlorate, palladium perchlorate, and gallium nitrate.

In some embodiments thereof, the dispersant is one or more of isopropanol, methanol, ethanol, ethyl acetate, acetonitrile, N-methylpyrrolidone, and dimethylformamide.

In some embodiments, before performing the step of transferring the mixed solution to a substrate and reacting at a temperature of −30° C.-50° C. for 1-48 hours to obtain a metal-conductive polymer composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO, the method further comprises the following step: performing cleaning treatment on a surface of the substrate using a hydrated organic solvent.

In some embodiments thereof, the step of performing cleaning treatment on a surface of the substrate using a hydrated organic solvent specifically comprises: coating an ionic polymer solution to the surface of the substrate, and drying in natural air; wherein a dosage of the ionic polymer is 0-1 mg/cm².

In some embodiments thereof, the substrate comprises polytetrafluoroethylene film, polyvinylidene fluoride film, polytetrafluoroethylene carbon film, polyethylene film, non-woven fabric, cellulose membrane film, and modified substrate materials thereof.

In some embodiments thereof, in the step of transferring the mixed solution to a hydrophobic film substrate and reacting at a temperature of −30° C.-50° C. for 1-48 hours to obtain a metal-conductive polymer composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO, the transferring comprises one of droplet coating, spraying coating, scraping coating, and spin coating.

A second purpose of the present application provides a gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO, which is obtained by preparation using the preparation method.

A third purpose of the present application provides an application of the gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO in CO₂ electrocatalyzing and reduction reactions.

The present application adopts the above technical solutions, and its advantageous effects are as follows.

The preparation method of a gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO provided by the present application comprises: mixing a conductive polymer monomer solution with a molar ratio of 100:1˜1:100 with a metal salt solution, and adding a dispersant to form a mixed solution; transferring the mixed solution to a substrate and reacting at a temperature of −30° C.-50° C. for 1-48 hours to obtain a metal-conductive polymer composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO. In the preparation method of a gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO of the present application, by the method of using metal ions to self-initiate in-situ growth of conductive polymer monomers, a metal-conductive polymer integrated composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO is formed. Due to the characteristics of the conductive polymer, the gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO can provide more nucleation sites, achieving similar catalytic effect while reducing use amount of metal; secondly, the special structure of the conductive polymer increases an electron transfer rate and adsorption amount of CO₂ on the surface of the electrode, which is beneficial for improving product selectivity; finally, the conductive polymer has a long chain structure of organic macromolecules, which can be crosslinked to stabilize the substrate, metal particles, and metal-ligand complexes in combination therewith, thereby improving the stability of the electrode.

Furthermore, the preparation method of a gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO of the present invention has characteristics of simple preparation, low price, environmental friendliness, high efficiency and stability, thereby having prospect for large-scale industrial application.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to explain technical solutions of embodiments of the present application more clearly, drawings required to be used in description of the embodiments of the present application or of the prior art will be briefly introduced below. It is obvious that the drawings in the following description are only some embodiments of the present application. For one of ordinary skill in the art, other drawings can be further obtained according to these drawings on the premise of paying no creative work.

FIG. 1 is a flow chart of steps of a preparation method of a gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO provided by this embodiment.

FIG. 2 is an SEM schematic diagram of a metal-conductive polymer composite based gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO of Embodiment 1.

FIG. 3 is a selectivity bar chart of using a metal-conductive polymer composite electrode under different currents to produce CO by catalyzing and reduction in Embodiment 1.

DETAILED DESCRIPTION

Embodiments of the present application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numbers throughout represent the same or similar components or components with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present application, but cannot be understood as limiting the present application.

In the description of the present application, it should be understood that the orientations or position relationships indicated by the terms “up”, “down”, “horizontal”, “inside”, “outside”, and the like are orientations or position relationships based on the shown in the accompany drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they cannot be understood as any limitation to the present application.

In addition, the terms “first” and “second” are only used for the purpose of description, and cannot be understood as indicating or implying relative importance or implying the quantity of technical features indicated. Therefore, features limited by “first” and “second” can explicitly or implicitly include one or more of these features. In the description of the present application, “multiple” means two or more, unless otherwise specified.

In order to make the purposes, technical solutions, and advantages of the present application be clearer and more understandable, the present application is further illustrated in detail below in combination with the accompany drawings and embodiments.

Referring to FIG. 1, which is a flow chart of steps of a preparation method of a gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO provided by this embodiment, and includes the following step S110 to step S120. Realizing methods of the steps are explained in detail below.

Step S110: mixing a conductive polymer monomer solution with a molar ratio of 100:1˜1:100 with a metal salt solution, and adding a dispersant to form a mixed solution.

In this embodiment, before performing the step of mixing a conductive polymer monomer solution with a metal salt solution and adding a dispersant to form a mixed solution, the following step is further included: performing pre-constant temperature treatment on the conductive polymer monomer solution and the metal salt solution at 30° C. to −18° C., thereby reducing a reaction rate and improving electrode uniformity.

In this embodiment, the conductive polymer monomer solution is prepared by the following method: adding conductive polymer monomer to an acidic solution, and mixing evenly to obtain the conductive polymer monomer solution, wherein the molar ratio of the conductive polymer monomer to the acidic solution is 50:1-1:50.

In this embodiment, the conductive polymer monomer is one or more of aniline, pyrrole, thiophene, indole, pyridine, carbazole, dopamine, and p-phenylacetylene monomers.

In this embodiment, the solute of the acidic solution comprises one or more of hydrochloric acid, sulfuric acid, nitric acid, formic acid, acetic acid, dodecylbenzenesulfonic acid, p-toluenesulfonic acid, and camphor sulfonic acid; the solvent of the acidic solution is one or more of water, methanol, ethanol, isopropanol, acetonitrile, ethyl acetate, chloroform, dichloromethane, acetone, N-methylpyrrolidone, dimethylformamide, and dimethyl sulfoxide.

In this embodiment, the metal salt comprises one or more of silver nitrate, silver hypochlorite, silver chlorate, silver perchlorate, silver fluoride, silver acetate, silver trifluoroacetate, silver trifluoromethanesulfonate, silver methanesulfonate, silver p-toluenesulfonate, chloroauric acid, zinc nitrate, zinc hypochlorite, zinc chlorate, zinc perchlorate, palladium nitrate, palladium hypochlorite, palladium chlorate, palladium perchlorate, and gallium nitrate.

In this embodiment, the dispersant is one or more of isopropanol, methanol, ethanol, ethyl acetate, acetonitrile, N-methylpyrrolidone, and dimethylformamide.

The main chain of the conductive polymer provided in this embodiment usually has a conjugated structure, and the polymerization process thereof is mostly oxidative coupling of single ring precursors. Therefore, oxidative metal salts can be used instead of initiators to initiate in-situ polymerization, and the catalytic selectivity and stability are improved by designing metal-conductive polymer composite electrodes; the conductive polymer is in a long chain structure of organic macromolecules, which can stabilize their bound substrates, metal particles, and metal-ligand complexes through cross-linking, thereby improving the stability of the electrode.

Step S120: transferring the mixed solution to a substrate and reacting at a temperature of −30° C.-50° C. for 1-48 hours to obtain a metal-conductive polymer composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO.

In this embodiment, before performing the step of transferring the mixed solution to a substrate and reacting at a temperature of −30° C.-50° C. for 1-48 hours to obtain a metal-conductive polymer composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO, the following step is further included: performing cleaning treatment on a surface of the substrate using a hydrated organic solvent.

In this embodiment, the step of performing cleaning treatment on a surface of the substrate using a hydrated organic solvent specifically comprises: coating an ionic polymer solution to the surface of the substrate, and drying in natural air; wherein a dosage of the ionic polymer is 0-1 mg/cm².

In this embodiment, the substrate comprises polytetrafluoroethylene film, polyvinylidene fluoride film, polytetrafluoroethylene carbon film, polyethylene film, non-woven fabric, cellulose membrane film, and modified substrate materials thereof.

In this embodiment, in the step of transferring the mixed solution to a hydrophobic film substrate and reacting at a temperature of −30° C.-50° C. for 1-48 hours to obtain a metal-conductive polymer composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO, the transferring comprises one of droplet coating, spraying coating, scraping coating, and spin coating.

The metal-conductive polymer composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO provided by the present invention can be used in a reaction system of electrocatalyzing CO₂ to reduce and produce CO.

The gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO obtained by preparation by the above embodiment of the present application, by the method of using metal ions to self-initiate in-situ growth of conductive polymer monomers, forms the metal-conductive polymer integrated composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO. Due to the characteristics of the conductive polymer, the gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO can provide more nucleation sites, thereby reducing the use amount of metals at the same time of achieving similar catalytic effect. The gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO obtained by preparation by the above embodiment of the present application can be used in a reaction system of electrocatalyzing CO₂ to reduce and produce CO, and can increase CO₂ adsorption capacity on the surface of the catalyst. At the same time, the special structure of the conductive polymer increases the electron conduction rate, increases the opportunity for electron to reduce CO₂ or intermediates, improves the selectivity of reducing CO₂ to produce CO, and realizes circular economic utilization and conversion of carbon dioxide.

The following detailed explanations are all exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in this article have the same meanings as those commonly understood by ordinary technical personnel in the technical field to which the present invention belongs.

It should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit exemplary embodiments according to the present application.

Embodiment 1

A preparation method of a gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO provided by this embodiment includes the following steps:

• • (1) preparing aniline monomer solution (solution A): taking 0.8 mmol acetic acid solution, adding 0.4 mmol aniline, and then adding 200 μL isopropanol, stirring and mixing evenly, and performing pre-cooling treatment for 2 hours;
  • (2) preparing silver nitrate solution (solution B): taking 0.1 mmol silver nitrate solution, adding 100 μL isopropanol, and performing pre-cooling treatment for 2 hours;
  • (3) uniformly mixing the solution A and the solution B in the Embodiment 1, and quickly dropwise adding them onto a surface of a PTFE carbon film to perform metal ion self-initiated in-situ polymerization reaction; wherein a reaction temperature is 0° C., and a reaction time is 12 hours; preparing to obtain a silver-polyaniline composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO, which is labeled as AgNO₃(1)-PANI(4)-nafion0-PTFE(C) composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO.

Table 1 shows the electrocatalytic performance of the catalyst sample prepared in Embodiment 1 at different currents.

	Current/mA	100	200	300
	Faraday efficiency	>94.9	>95.4	>93.3
	of CO/%

Referring to FIG. 2, which is an SEM schematic diagram of a metal-conductive polymer composite based gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO of the Embodiment 1. FIG. 3 is a selectivity bar chart of using a metal-conductive polymer composite electrode under different currents to produce CO by catalyzing and reduction in Embodiment 1.

Embodiment 2

A preparation method of a gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO provided by this embodiment includes the following steps:

• • (1) preparing aniline monomer solution (solution A): taking 0.8 mmol acetic acid solution, adding 0.4 mmol aniline, and then adding 200 μL isopropanol, stirring and mixing evenly, and performing pre-cooling treatment for 2 hours;
  • (2) preparing silver nitrate solution (solution B): taking 0.1 mmol silver nitrate solution, adding 100 μL isopropanol, and performing pre-cooling treatment for 2 hours;
  • (3) preparing Nafion solution: taking 30 μL Nafion, dispersing it in 1000 μL isopropanol, dropwise adding them on a 4×4 cm² PTFE carbon film substrate;
  • (4) uniformly mixing the solution A and the solution B in the Embodiment 2, and quickly dropwise adding them onto a surface of a PTFE carbon film to perform metal ion self-initiated in-situ polymerization reaction; wherein a reaction temperature is 0° C., and a reaction time is 12 hours; preparing to obtain a silver-polyaniline composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO, which is labeled as AgNO₃(1)-PANI(4)-nafion30-PTFE(C) composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO.

Table 2 shows the electrocatalytic performance of the catalyst sample prepared in Embodiment 2 at different currents.

	C/mA	100	200	300
	Faraday efficiency	>91.4	>92.1	>90.3
	of CO/%

Embodiment 3

A preparation method of a gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO provided by this embodiment includes the following steps:

• • (1) preparing aniline monomer solution (solution A): taking 0.8 mmol acetic acid solution, adding 0.4 mmol aniline, and then adding 200 μL isopropanol, stirring and mixing evenly, and performing pre-cooling treatment for 2 hours;
  • (2) preparing silver nitrate solution (solution B): taking 0.1 mmol silver nitrate solution, adding 100 μL isopropanol, and performing pre-cooling treatment for 2 hours;
  • (3) preparing Nafion solution: taking 10 μL Nafion, dispersing it in 1000 μL isopropanol, dropwise adding them on a 4×4 cm² PTFE carbon film substrate;
  • (4) uniformly mixing the solution A and the solution B in the Embodiment 3, and quickly dropwise adding them onto a surface of a PTFE carbon film to perform metal ion self-initiated in-situ polymerization reaction; wherein a reaction temperature is 0° C., and a reaction time is 12 hours; preparing to obtain a silver-polyaniline composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO, which is labeled as AgNO₃(1)-PANI(4)-nafion10-PTFE(C) composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO.

Table 3 shows the electrocatalytic performance of the catalyst sample prepared in Embodiment 3 at different currents.

	Current/mA	100	200	300
	Faraday efficiency	>88.6	>91.7	88.8
	of CO/%

Embodiment 4

A preparation method of a gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO provided by this Embodiment 4 includes the following steps:

• • (1) preparing aniline monomer solution (solution A): taking 0.8 mmol acetic acid solution, adding 0.4 mmol aniline, and then adding 200 μL isopropanol, stirring and mixing evenly, and performing pre-cooling treatment for 2 hours;
  • (2) preparing silver trifluoromethylsulfonate solution (solution B): taking 0.1 mmol silver trifluoromethylsulfonate solution, adding 100 μL isopropanol, and performing pre-cooling treatment for 2 hours;
  • (3) uniformly mixing the solution A and the solution B in the Embodiment 4, and quickly dropwise adding them onto a surface of a PTFE carbon film to perform metal ion self-initiated in-situ polymerization reaction; wherein a reaction temperature is 0° C., and a reaction time is 12 hours; preparing to obtain a silver-polyaniline composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO, which is labeled as AgOTf(1)-PANI(4)-nafion0-PTFE(C) composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO.

Table 4 shows the electrocatalytic performance of the catalyst sample prepared in Embodiment 4 at different currents.

	Current/mA	100	200	300
	Faraday efficiency	>93.7	>94.1	>91.5
	of CO/%

Embodiment 5

A preparation method of a gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO provided by this embodiment includes the following steps:

• • (1) preparing aniline monomer solution (solution A): taking 0.8 mmol acetic acid solution, adding 0.4 mmol aniline, and then adding 200 μL isopropanol, stirring and mixing evenly, and performing pre-cooling treatment for 2 hours;
  • (2) preparing silver nitrate solution (solution B): taking 0.0625 mmol silver nitrate solution, adding 100 μL isopropanol, and performing pre-cooling treatment for 2 hours;
  • (3) uniformly mixing the solution A and the solution B in the Embodiment 5, and quickly dropwise adding them onto a surface of a PTFE carbon film to perform metal ion self-initiated in-situ polymerization reaction; wherein a reaction temperature is 0° C., and a reaction time is 12 hours; preparing to obtain a silver-polyaniline composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO, which is labeled as AgNO₃(1)-PANI(64)-nafion0-PTFE(C) composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO.

Table 5 shows the electrocatalytic performance of the catalyst sample prepared in Embodiment 5 at different currents.

	Current/mA	100	200	300
	Faraday efficiency	>90.2	>95.1	>93.5
	of CO/%

Comparative Example 1

Taking 0.8 mmol acetic acid solution, 0.4 mmol polyaniline, 0.1 mmol AgNO₃, and 10 μL Nafion solution, dispersing them in 1000 μL isopropanol, and dropwise adding them on a 4×4 cm² PTFE carbon film substrate, thereby obtaining a non-in-situ polymerized silver-polyaniline composite gas phase diffusion electrode for electrocatalyzing CO₂ to reduce and produce CO, and performing performance evaluation under the same operating conditions in the same electrolytic cell.

Due to the poor adhesion between the non-in-situ polymerized silver-polyaniline composite catalyst and the substrate, experiments cannot be conducted in a gas-phase diffusion electrolytic cell.

Effect Verification

A gas phase diffusion electrolytic cell is used as a CO₂ catalytic reduction reaction device to perform performance evaluation for the metal-conducitive polymer composite electrodes of the Embodiments 1-5 of the present invention and of the Comparative Example 1. The specific measurement conditions are as follows.

CO is detected by online gas chromatography (GC2014, Shimadzu, Japan) with a sampling interval of 40 minutes.

CO₂ Electrical Reduction Performance Test in the Gas Phase Diffusion Electrolytic Cell:

• • (1) reference electrode: mercury-mercury oxide electrode;
  • (2) counter electrode: platinum plate electrode;
  • (3) working electrode: metal-conductive polymer composite electrode (1×1 cm²);
  • (4) electrolyte: 1M KOH solution;
  • (5) ion exchange membrane: Fumasep FAA-3-PK-130;
  • (6) CO₂ flow rate: 20 sccm.

Calculation of Faraday Efficiency (FE):

for gaseous products, we usually use a gas chromatograph for quantitative analysis, and a formula of calculating Faraday efficiency is:

$\mathrm{FE}=\frac{{\mathrm{zFC}}_i\mathrm{vP}}{\mathrm{jRT}};$

wherein:

• • in this formula, z is the number of transferred electrons; F is the Faraday constant (96485 C·mol⁻¹); C is the concentration of the product (ppm×10⁻⁶); v is the flow rate of gas entering the chromatography (m³·s⁻¹); P is the pressure of the chromatographic injection ring (Pa); j is the current density (A); R is the ideal gas constant (8.314 J·mol⁻¹·K⁻¹); T is the temperature of the chromatographic injection ring (K).

It can be seen from the Embodiments 1-5 and the Comparative Example 1 that the metal-conducitive polymer composite electrode provided by the present invention, when being used in the process of electrocatalyzing CO₂ to reduce and produce CO, both the selectivity of the reaction and the stability of the electrodes are significantly improved.

It can be understood that the various technical features of the above described embodiments can be combined arbitrarily. In order to make the description be concise, all possible combinations of the various technical feature in the above embodiments have not been described. However, as long as there is no contradiction in the combination of these technical features, they should be considered as the scope of this specification.

The above are only preferred embodiments of the present application and only specifically describe the technical principles of the present application. These descriptions are only intended to explain the principles of the present application and cannot be interpreted in any way as limiting the protection scope of the present application. Based on this explanation, any modification, equivalent replacement, and improvement made within the spirit and principles of the present application, as well as other specific implementations of the present application that can be associated without the need for creative labor by technical personnel in this field, shall be included in the protection scope of the present application.

Claims

1. A preparation method of a gas phase diffusion electrode for electrocatalyzing CO2 to reduce and produce CO, comprising the following steps: mixing a conductive polymer monomer solution with a molar ratio of 100:1˜1:100 with a metal salt solution, and adding a dispersant to form a mixed solution;transferring the mixed solution to a substrate and reacting at a temperature of −30° C.-50° C. for 1-48 hours to obtain a metal-conductive polymer composite gas phase diffusion electrode for electrocatalyzing CO2 to reduce and produce CO.

2. The preparation method of a gas phase diffusion electrode for electrocatalyzing CO2 to reduce and produce CO according to claim 1, wherein before performing the step of mixing a conductive polymer monomer solution with a metal salt solution and adding a dispersant to form a mixed solution, the method further comprises the following step: performing pre-constant temperature treatment on the conductive polymer monomer solution and the metal salt solution at 30° C. to −18° C.

3. The preparation method of a gas phase diffusion electrode for electrocatalyzing CO2 to reduce and produce CO according to claim 1, wherein the conductive polymer monomer solution is prepared by the following method: adding conductive polymer monomer to an acidic solution, and mixing evenly to obtain the conductive polymer monomer solution, wherein the molar ratio of the conductive polymer monomer to the acidic solution is 50:1-1:50.

4. The preparation method of a gas phase diffusion electrode for electrocatalyzing CO2 to reduce and produce CO according to claim 3, wherein the conductive polymer monomer is one or more of aniline, pyrrole, thiophene, indole, pyridine, carbazole, dopamine, and p-phenylacetylene monomers.

5. The preparation method of a gas phase diffusion electrode for electrocatalyzing CO2 to reduce and produce CO according to claim 3, wherein the solute of the acidic solution comprises one or more of hydrochloric acid, sulfuric acid, nitric acid, formic acid, acetic acid, dodecylbenzenesulfonic acid, p-toluenesulfonic acid, and camphor sulfonic acid; the solvent of the acidic solution is one or more of water, methanol, ethanol, isopropanol, acetonitrile, ethyl acetate, chloroform, dichloromethane, acetone, N-methylpyrrolidone, dimethylformamide, and dimethyl sulfoxide.

6. The preparation method of a gas phase diffusion electrode for electrocatalyzing CO2 to reduce and produce CO according to claim 1, wherein the metal salt comprises one or more of silver nitrate, silver hypochlorite, silver chlorate, silver perchlorate, silver fluoride, silver acetate, silver trifluoroacetate, silver trifluoromethanesulfonate, silver methanesulfonate, silver p-toluenesulfonate, chloroauric acid, zinc nitrate, zinc hypochlorite, zinc chlorate, zinc perchlorate, palladium nitrate, palladium hypochlorite, palladium chlorate, palladium perchlorate, and gallium nitrate.

7. The preparation method of a gas phase diffusion electrode for electrocatalyzing CO2 to reduce and produce CO according to claim 1, wherein the dispersant is one or more of isopropanol, methanol, ethanol, ethyl acetate, acetonitrile, N-methylpyrrolidone, and dimethylformamide.

8. The preparation method of a gas phase diffusion electrode for electrocatalyzing CO2 to reduce and produce CO according to claim 1, wherein before performing the step of transferring the mixed solution to a substrate and reacting at a temperature of −30-50° C. for 1-48 hours to obtain a metal-conductive polymer composite gas phase diffusion electrode for electrocatalyzing CO2 to reduce and produce CO, the method further comprises the following step: performing cleaning treatment on a surface of the substrate using a hydrated organic solvent.

9. The preparation method of a gas phase diffusion electrode for electrocatalyzing CO2 to reduce and produce CO according to claim 8, wherein the step of performing cleaning treatment on a surface of the substrate using a hydrated organic solvent specifically comprises: coating an ionic polymer solution to the surface of the substrate, and drying in natural air; wherein a dosage of the ionic polymer is 0-1 mg/cm2.

10. The preparation method of a gas phase diffusion electrode for electrocatalyzing CO2 to reduce and produce CO according to claim 1, wherein the substrate comprises polytetrafluoroethylene film, polyvinylidene fluoride film, polytetrafluoroethylene carbon film, polyethylene film, non-woven fabric, cellulose membrane film, and modified substrate materials thereof.

11. The preparation method of a gas phase diffusion electrode for electrocatalyzing CO2 to reduce and produce CO according to claim 1, wherein in the step of transferring the mixed solution to a hydrophobic film substrate and reacting at a temperature of −30-50° C. for 1-48 hours to obtain a metal-conductive polymer composite gas phase diffusion electrode for electrocatalyzing CO2 to reduce and produce CO, the transferring comprises one of droplet coating, spraying coating, scraping coating, and spin coating.

12. A gas phase diffusion electrode for electrocatalyzing CO2 to reduce and produce CO obtained by preparation by the preparation method according to claim 1.

13. An application of a gas phase diffusion electrode for electrocatalyzing CO2 to reduce and produce CO according to claim 12 in electrocatalyzing and reduction reaction of CO2.