Electrode for electrocatalytic reduction of carbon dioxide as well as preparation method and application of electrode

Abstract

The invention relates to the technical field of CO2 electrocatalytic reduction, and discloses an electrode for electrocatalytic carbon dioxide reduction and a preparation method and application thereof. The electrode comprises a base material layer, a catalyst layer and an ionomer layer which are sequentially arranged, the catalyst layer comprises catalyst particles and perfluorinated sulfonic acid resin; and the ionomer layer comprises polyarylimidazole resin. When the electrode disclosed by the invention is used for preparing CO through electrocatalytic CO2 reduction, hydrogen evolution side reaction can be remarkably inhibited in an acidic electrolyte, the efficiency of preparing CO through CO2 reduction is improved, and meanwhile, the electrode disclosed by the invention also has relatively high stability and still can keep relatively high CO selectivity and catalytic activity after long-time work.

Description

Technical Field

[0001] This invention relates to the field of CO2 electrocatalytic reduction technology, and in particular to an electrode for electrocatalytic carbon dioxide reduction, its preparation method, and its application. Background Technology

[0002] As a key factor driving global warming, carbon dioxide (CO2) capture, storage, and utilization have become a core focus of research. Electrocatalytic CO2 reduction, as an emerging CO2 utilization technology, has attracted increasing research attention due to its unique advantages, such as high compatibility with renewable energy sources, mild reaction conditions, ease of scale-up, high product selectivity, and low separation difficulty.

[0003] In electrocatalytic CO2 reduction, acidic electrolytes exhibit unique advantages over neutral or alkaline systems due to their high proton concentration. On one hand, the acidic environment effectively inhibits carbonate deposition on the electrode surface, preventing the active sites from being covered. On the other hand, high proton flux accelerates reaction kinetics, theoretically benefiting current density and product formation rate. However, the widespread application of acidic systems still faces significant challenges: highly corrosive environments easily lead to the dissolution or oxidative deactivation of catalyst active sites; under acidic conditions, competition between the hydrogen evolution reaction and the CO2 reduction reaction intensifies, severely reducing the selectivity of the target product, mainly due to the high proton concentration (H+). + It is readily reduced to hydrogen gas (2H₂O) near the electrode surface. + + 2e - → H2), this reaction is kinetically superior to the CO2 reduction process involving multiple electron transfers.

[0004] Patent CN117364117A discloses a membrane electrode structure and preparation method for acidic electrocatalytic carbon dioxide reduction. The preparation method includes: first, spraying a catalyst onto carbon paper; then, spraying a certain amount of ionomer mixture onto the catalyst layer to form a gas diffusion electrode with a functional layer; and finally, assembling and laminating to form a membrane electrode assembly. By covering the catalyst layer with an ionomer composite layer, the diffusion of hydrogen ions from the anolyte to the cathode can be slowed, inhibiting the hydrogen evolution reaction, thereby enabling the entire electrode to exhibit a high Faraday current efficiency for electrocatalytic carbon dioxide reduction. However, this method has limited effectiveness in suppressing the hydrogen evolution side reaction, and the efficiency of CO2 reduction to CO remains low when the electrolyte pH is low. Summary of the Invention

[0005] To address the aforementioned technical problem—namely, the difficulty of existing methods in significantly suppressing hydrogen evolution side reactions and improving the efficiency of CO2 reduction to CO—this invention provides an electrode for electrocatalytic carbon dioxide reduction, its preparation method, and its application. When used for electrocatalytic CO2 reduction to CO, the electrode of this invention can significantly suppress hydrogen evolution side reactions in an acidic electrolyte, thereby improving the efficiency of CO2 reduction to CO.

[0006] The specific technical solution of this invention is as follows: In a first aspect, the present invention provides an electrode for electrocatalytic carbon dioxide reduction, comprising a substrate layer, a catalyst layer and an ionomer layer disposed sequentially; the catalyst layer comprising catalyst particles and perfluorosulfonic acid resin; and the ionomer layer comprising polyarylimidazolium resin.

[0007] In this invention, by adding perfluorosulfonic acid resin to the catalyst layer and covering the catalyst layer with an ionomer layer containing polyaryl imidazolium resin, the dynamic ion pairs constructed by the two ionomers (perfluorosulfonic acid resin and polyaryl imidazolium resin) can produce a synergistic effect. This allows the electrode to significantly suppress the hydrogen evolution side reaction and improve CO selectivity when used in an acidic system. The specific synergistic mechanism is as follows: The polyaryl imidazolium resin consists of a polyaryl main chain and imidazolium side chains. In an acidic system, the imidazolium cations formed by its side chains can construct a dynamically stable local alkaline microenvironment on the electrode surface, which has the ability to enrich OH groups. - And reject H + The function of perfluorosulfonic acid resins: Perfluorosulfonic acid resins utilize their sulfonic acid groups to efficiently transport protons. In the case of imidazolium cation repulsion H... + H transported by sulfonic acid groups + Under the combined effect of the two ionomers in the electrode, the dynamic ion pairs formed at the interface can accelerate H + By moving away from the substrate layer and the area near the catalyst, H can be better avoided. + The polymer accepts electrons at the electrode and is converted into H2, suppressing the competitive hydrogen evolution reaction. In the above process, the polyaryl main chain of the polyaryl imidazole resin has strong rigidity, which can limit the mobility of the polyaryl imidazole molecular chain, thus providing a stable structural basis for the synergistic effect between the two ionomers.

[0008] In addition to the electrostatic regulation effect and suppression of hydrogen evolution side reaction, the imidazole side chain in polyarylimidazolium resin can also stabilize key reaction intermediates (such as ·COOH radicals) in the electrocatalytic reduction of CO2 to CO through π-π interactions, thereby promoting the reaction and improving the reaction efficiency.

[0009] Preferably, the catalyst particles are silver nanoparticles.

[0010] Preferably, the mass ratio of the catalyst particles to the perfluorosulfonic acid resin is 20~100:1; and the loading of the catalyst particles in the electrode is 1.8~2.2 mg / cm³. 2 .

[0011] Preferably, the substrate layer is carbon paper.

[0012] Secondly, the present invention provides a method for preparing the electrode, comprising: S1: A dispersion containing catalyst particles and perfluorosulfonic acid resin is coated onto the surface of the substrate layer and dried to form a catalyst layer; S2: Coat the surface of the catalyst layer with a polyarylimidazolium resin solution and let it stand to obtain the electrode.

[0013] Preferably, in step S1, the dispersion medium in the dispersion is anhydrous ethanol; and in step S2, the solvent in the polyaryl imidazole resin solution is methanol.

[0014] Preferably, in step S1, the content of catalyst particles in the dispersion is 0.005~0.015 g / mL; in step S2, the content of polyarylimidazolium resin in the polyarylimidazolium resin solution is 0.1~5 wt%.

[0015] Preferably, in step S2, the settling time is 2-3 hours.

[0016] Thirdly, the present invention provides the application of the electrode in the electrocatalytic reduction of CO2 to CO, wherein the electrocatalytic reduction of CO2 to CO is carried out under acidic conditions.

[0017] Preferably, in the process of electrocatalytic CO2 reduction to CO, the cathode is the electrode, the anode is a titanium mesh loaded with iridium oxide, and the electrolyte is a sulfate solution.

[0018] Preferably, the electrolyte has a sulfate content of 0.1~0.15 mol / L and a pH of 1~3; the current density during the electrocatalytic reduction of CO2 to CO is 20~300 mA / cm². 2 The CO2 flow rate is 30~40 sccm.

[0019] Compared with the prior art, the present invention has the following advantages: (1) In the electrode of the present invention, by adding perfluorosulfonic acid resin to the catalyst layer and covering the catalyst layer with polyaryl imidazole resin, the dynamic ions formed between the perfluorosulfonic acid resin and the polyaryl imidazole resin can be used to produce a synergistic effect in suppressing hydrogen evolution side reactions, so that the electrode can significantly reduce competitive hydrogen evolution reactions in acidic electrolyte and improve the efficiency of CO2 reduction to CO.

[0020] (2) When the electrode of the present invention is used in the electrocatalytic reduction of CO2 to CO, it can achieve high CO selectivity and CO generation efficiency, and also has high stability. It can maintain high CO selectivity and CO generation efficiency even after long-term operation, which helps to provide a general solution for the industrialization of electrocatalytic CO2 reduction and is of great significance for its industrial promotion. Attached Figure Description

[0021] Figure 1 This is a scanning electron microscope image of the electrode prepared in Example 1.

[0022] Figure 2 This is a scanning electron microscope image of the electrode prepared in Comparative Example 1.

[0023] Figure 3 This is the Faraday efficiency diagram of the electrode prepared in Example 1.

[0024] Figure 4 This is a Faraday efficiency diagram of the electrode prepared in Comparative Example 1.

[0025] Figure 5 This is a Faraday efficiency diagram of the electrode prepared in Comparative Example 2.

[0026] Figure 6 This is a Faraday efficiency diagram of the electrode prepared in Comparative Example 3.

[0027] Figure 7 This is a Faraday efficiency diagram of the electrode prepared in Comparative Example 4.

[0028] Figure 8 This is a graph showing the stability test results of the electrode prepared in Comparative Example 1.

[0029] Figure 9 This is a graph showing the stability test results of the electrode prepared in Example 1. Detailed Implementation

[0030] The present invention will now be further described.

[0031] First, the present invention relates to an electrode for electrocatalytic carbon dioxide reduction, comprising a substrate layer, a catalyst layer and an ionomer layer disposed sequentially; the catalyst layer comprising catalyst particles and perfluorosulfonic acid resin; and the ionomer layer comprising polyarylimidazolium resin.

[0032] In some specific embodiments, the catalyst particles are silver nanoparticles.

[0033] In some specific embodiments, the catalyst particles are loaded at a concentration of 1.8–2.2 mg / cm³ in the electrode. 2 .

[0034] In some specific embodiments, the mass ratio of the catalyst particles to the perfluorosulfonic acid resin is 100:1; In some specific embodiments, the substrate layer is carbon paper.

[0035] Second, the present invention relates to a method for preparing the electrode, comprising: S1: A dispersion containing catalyst particles and perfluorosulfonic acid resin is coated onto the surface of the substrate layer and dried to form a catalyst layer; S2: Coat the surface of the catalyst layer with a polyarylimidazolium resin solution and let it stand to obtain the electrode.

[0036] In some specific embodiments, in step S1, the dispersion medium in the dispersion is anhydrous ethanol.

[0037] In some specific embodiments, in step S1, the content of catalyst particles in the dispersion is 0.005~0.015 g / mL.

[0038] In some specific embodiments, in step S2, the solvent in the polyarylimidazolium resin solution is methanol.

[0039] In some specific embodiments, in step S2, the content of polyarylimidazolium resin in the polyarylimidazolium resin solution is 0.1~5 wt%.

[0040] In some specific embodiments, the settling time in step S2 is 2 to 3 hours.

[0041] In some specific embodiments, the coating method in steps S1 and S2 is spraying.

[0042] Third, the present invention relates to the application of the electrode in the electrocatalytic reduction of CO2 to CO, wherein the electrocatalytic reduction of CO2 to CO is carried out under acidic conditions.

[0043] In some specific embodiments, during the electrocatalytic reduction of CO2 to CO, the cathode is the electrode, the anode is a titanium mesh supported on iridium oxide, and the electrolyte is a sulfate solution; the sulfate content in the electrolyte is 0.1~0.15 mol / L, and the pH is 1~3.

[0044] In some specific embodiments, during the electrocatalytic reduction of CO2 to CO, the current density is 20~300 mA / cm². 2 The CO2 flow rate is 30~40 sccm.

[0045] The present invention will now be described with reference to the accompanying drawings, specific embodiments, and comparative examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0046] The polyaryl imidazole resin, polyaryl piperidine resin, and polyalkyl imidazole resin used in the following embodiments and comparative examples were purchased from Zhizi Engine (Hangzhou) Technology, and their product names are Gen B-IMD, Gen B-PP, and Gen B-Hex, respectively, but the scope of protection of this invention is not limited thereto.

[0047] Example 1: Electrode Preparation An electrode for electrocatalytic carbon dioxide reduction is prepared through the following steps: S1: 20 mg of silver nanoparticles (Ag NPs) and 20 μL of 5wt% perfluorosulfonic acid resin dispersion were dispersed in 2 mL of anhydrous ethanol (analytical grade). The mixture was then ultrasonically treated in an ultrasonic cleaner for 60 minutes to form a uniform and stable black catalyst ink. The catalyst ink was then uniformly sprayed onto hydrophobic carbon paper (SGL 28BC) (5 cm) using a spray gun (nozzle diameter 0.5 mm). 2 On the surface, the silver loading was controlled at 2.0 ± 0.2 mg / cm³. 2 The paper is then placed in a vacuum drying oven at 60°C for 2 hours to remove the solvent and enhance the interfacial bonding strength between the catalyst and the substrate, resulting in carbon paper with a catalyst layer.

[0048] S2: Dissolve 40 μL of 5 wt% polyarylimidazolium resin dispersion in 2 mL of methanol, and sonicate for 10 minutes to ensure complete dissolution, forming an ionomer solution. Using the same spray gun as in step S1, uniformly spray the ionomer solution onto the surface of the cathode electrode to form a modification layer. After spraying, allow it to stand at room temperature for 2 hours to allow the ionomer molecules to self-assemble into a dense film layer through intermolecular forces, obtaining the electrode of this embodiment.

[0049] The electrode prepared in this embodiment consists of a substrate layer, a catalyst layer, and an ionomer layer from bottom to top. The substrate layer is carbon paper, the catalyst layer is composed of silver nanoparticles and perfluorosulfonic acid resin, and the ionomer layer is composed of polyarylimidazolium resin.

[0050] Comparative Example 1: Electrode Preparation The only difference between this comparative example and Example 1 is that the electrode in this comparative example is not coated with an ionomer layer; all other raw materials and steps are the same as in Example 1. Specifically, this comparative example prepares an electrode for electrocatalytic carbon dioxide reduction through the following steps: 20 mg of silver nanoparticles (Ag NPs) and 20 μL of 5wt% perfluorosulfonic acid resin dispersion were dispersed in 2 mL of anhydrous ethanol (analytical grade). The mixture was then ultrasonically treated in an ultrasonic cleaner for 60 minutes to form a uniform and stable black catalyst ink. The catalyst ink was then uniformly sprayed onto hydrophobic carbon paper (SGL 28BC) (5 cm²) using a spray gun (nozzle diameter 0.5 mm).2 On the surface, the silver loading was controlled at 2.0 ± 0.2 mg / cm³. 2 The electrode was then placed in a vacuum drying oven at 60°C for 2 hours to remove the solvent and enhance the interfacial bonding strength between the catalyst and the substrate, thus obtaining the electrode of this comparative example.

[0051] The electrode prepared in this comparative example consists of a substrate layer and a catalyst layer from bottom to top. The substrate layer is carbon paper, and the catalyst layer is composed of silver nanoparticles and perfluorosulfonic acid resin.

[0052] Comparative Example 2: Electrode Preparation The only difference between this comparative example and Example 1 is that the polyarylimidazolium resin in the ionomer layer of the electrode in this comparative example is replaced with polyarylpiperidine resin; all other raw materials and steps are the same as in Example 1. Specifically, this comparative example prepares an electrode for electrocatalytic carbon dioxide reduction through the following steps: S1: 20 mg of silver nanoparticles (Ag NPs) and 20 μL of 5wt% perfluorosulfonic acid resin dispersion were dispersed in 2 mL of anhydrous ethanol (analytical grade). The mixture was then ultrasonically treated in an ultrasonic cleaner for 60 minutes to form a uniform and stable black catalyst ink. The catalyst ink was then uniformly sprayed onto hydrophobic carbon paper (SGL 28BC) (5 cm) using a spray gun (nozzle diameter 0.5 mm). 2 On the surface, the silver loading was controlled at 2.0 ± 0.2 mg / cm³. 2 The paper is then placed in a vacuum drying oven at 60°C for 2 hours to remove the solvent and enhance the interfacial bonding strength between the catalyst and the substrate, resulting in carbon paper with a catalyst layer.

[0053] S2: Dissolve 40 μL of 5wt% polyarylpiperidine resin dispersion in 2 mL of methanol, and sonicate for 10 minutes to ensure complete dissolution, forming an ionomer solution. Using the same spray gun as in step S1, uniformly spray the ionomer solution onto the surface of the cathode electrode to form a modification layer. After spraying, allow it to stand at room temperature for 2 hours to allow the ionomer molecules to self-assemble into a dense film layer through intermolecular forces, obtaining the electrode of this comparative example.

[0054] The electrode prepared in this comparative example consists of a substrate layer, a catalyst layer, and an ionomer layer from bottom to top. The substrate layer is carbon paper, the catalyst layer is composed of silver nanoparticles and perfluorosulfonic acid resin, and the ionomer layer is composed of polyarylpiperidine resin.

[0055] Comparative Example 3: Electrode Preparation The only difference between this comparative example and Example 1 is that the polyaryl imidazole resin in the ionomer layer of the electrode in this comparative example is replaced with a polyalkyl imidazole resin; all other raw materials and steps are the same as in Example 1. Specifically, this comparative example prepares an electrode for electrocatalytic carbon dioxide reduction through the following steps: S1: 20 mg of silver nanoparticles (Ag NPs) and 20 μL of 5wt% perfluorosulfonic acid resin dispersion were dispersed in 2 mL of anhydrous ethanol (analytical grade). The mixture was then ultrasonically treated in an ultrasonic cleaner for 60 minutes to form a uniform and stable black catalyst ink. The catalyst ink was then uniformly sprayed onto hydrophobic carbon paper (SGL 28BC) (5 cm) using a spray gun (nozzle diameter 0.5 mm). 2 On the surface, the silver loading was controlled at 2.0 ± 0.2 mg / cm³. 2 The paper is then placed in a vacuum drying oven at 60°C for 2 hours to remove the solvent and enhance the interfacial bonding strength between the catalyst and the substrate, resulting in carbon paper with a catalyst layer.

[0056] S2: Dissolve 40 μL of 5 wt% polyalkylimidazolium resin dispersion in 2 mL of methanol, and sonicate for 10 minutes to ensure complete dissolution, forming an ionomer solution. Using the same spray gun as in step S1, uniformly spray the ionomer solution onto the surface of the cathode electrode to form a modification layer. After spraying, allow it to stand at room temperature for 2 hours to allow the ionomer molecules to self-assemble into a dense film layer through intermolecular forces, obtaining the electrode of this comparative example.

[0057] The electrode prepared in this comparative example consists of a substrate layer, a catalyst layer, and an ionomer layer from bottom to top. The substrate layer is carbon paper, the catalyst layer is composed of silver nanoparticles and perfluorosulfonic acid resin, and the ionomer layer is composed of polyalkylimidazolium resin.

[0058] Comparative Example 4: Electrode Preparation The only difference between this comparative example and Example 1 is that the perfluorosulfonic acid resin in the catalyst layer of the electrode in this comparative example is replaced with polystyrene resin (PS); all other raw materials and steps are the same as in Example 1. Specifically, this comparative example prepares an electrode for electrocatalytic carbon dioxide reduction through the following steps: S1: 20 mg of silver nanoparticles (Ag NPs) and 20 μL of 5wt% polystyrene resin dispersion were dispersed in 2 mL of anhydrous ethanol (analytical grade). The mixture was then ultrasonically treated in an ultrasonic cleaner for 60 minutes to form a uniform and stable black catalyst ink. The catalyst ink was then uniformly sprayed onto hydrophobic carbon paper (SGL 28BC) (5 cm) using a spray gun (nozzle diameter 0.5 mm). 2 On the surface, the silver loading was controlled at 2.0 ± 0.2 mg / cm³. 2The paper is then placed in a vacuum drying oven at 60°C for 2 hours to remove the solvent and enhance the interfacial bonding strength between the catalyst and the substrate, resulting in carbon paper with a catalyst layer.

[0059] S2: Dissolve 40 μL of 5 wt% polyarylimidazolium resin dispersion in 2 mL of methanol, and sonicate for 10 minutes to ensure complete dissolution, forming an ionomer solution. Using the same spray gun as in step S1, uniformly spray the ionomer solution onto the surface of the cathode electrode to form a modification layer. After spraying, allow it to stand at room temperature for 2 hours to allow the ionomer molecules to self-assemble into a dense film layer through intermolecular forces, obtaining the electrode of this comparative example.

[0060] The electrode prepared in this comparative example consists of a substrate layer, a catalyst layer, and an ionomer layer from bottom to top. The substrate layer is carbon paper, the catalyst layer is composed of silver nanoparticles and polytetrafluoroethylene resin, and the ionomer layer is composed of polyarylimidazolium resin.

[0061] Test Example 1: Electrode Surface Morphology Detection Electrodes prepared according to the methods of Example 1 and Comparative Example 1 were examined for their surface morphology using a scanning electron microscope. The results are as follows: Figure 1 and Figure 2 As shown in the figure. The results show that after the catalyst layer is sprayed onto the carbon paper, the silver nanoparticles (Ag NPs) are uniformly dispersed on the surface of the carbon paper substrate, with no obvious agglomeration. Figure 2 After further spraying an ionomer layer onto the catalyst layer, the ionomer layer continuously covers the surface of Ag NPs, forming a dense film. Figure 1 ).

[0062] Test Example 2: Effect of Ionomer Layer (Product Selectivity and Reaction Efficiency Test at pH=3) Electrodes prepared according to the methods of Example 1 and Comparative Example 1 were used as cathodes, and titanium mesh loaded with iridium oxide was used as anode. A 0.1 mol / L K₂SO₄ solution (pH adjusted to 3 with H₂SO₄) was used as the electrolyte. Carbon dioxide was continuously passed through at a flow rate of 30 sccm, and different current densities were applied. The Faraday efficiency (FE) of hydrogen and carbon monoxide was measured, and the results are as follows: Figure 3 and Figure 4 As shown ( Figure 3 and Figure 4 In this text, "Ag" indicates the electrode used in Comparative Example 1, and "Ag-IMD" indicates the electrode used in Example 1. The results show that by covering the catalyst layer in the electrode with an ionomer layer, the hydrogen evolution side reaction can be effectively suppressed, and the carbon monoxide selectivity can be improved. When the electrolyte pH is 3, the electrode of Example 1 exhibits a performance of 20–300 mA / cm². 2The carbon monoxide product selectivity was >70% at all current densities, and it also had a certain effect of inhibiting the competitive hydrogen evolution reaction even at high current densities.

[0063] Test Example 3: Effect of Ionomer Layer (Product Selectivity and Reaction Efficiency Test at pH=3) Electrodes prepared according to the methods of Example 1 and Comparative Example 2 were used as cathodes, and titanium mesh loaded with iridium oxide was used as anode. A 0.1 mol / L K₂SO₄ solution (pH adjusted to 3 with H₂SO₄) was used as the electrolyte. Carbon dioxide was continuously passed through at a flow rate of 30 sccm, and different current densities were applied. The Faraday efficiency (FE) of hydrogen and carbon monoxide was measured, and the results are as follows: Figure 3 and Figure 5 As shown ( Figure 3 and Figure 5 In the text, "Ag-PP" indicates the electrode used in Comparative Example 2, and "Ag-IMD" indicates the electrode used in Example 1. The results show that when a polyalkylimidazolium resin ionomer layer is present in the electrode (Comparative Example 2), the competitive hydrogen evolution reaction remains significant under high current density. However, when a polyarylimidazolium resin ionomer layer is placed above the catalyst layer of the electrode (Example 1), the competitive hydrogen evolution reaction can be suppressed to a certain extent, exhibiting a good suppression effect even under high current density conditions. The reason for this is that the imidazole groups in the side chains of the polyarylimidazolium resin are electron-rich π-systems, which can stabilize key reaction intermediates (such as ·COOH radicals) in the electrocatalytic reduction of CO2 to CO through π-π interactions, thereby promoting the reaction and improving reaction efficiency.

[0064] Test Example 4: Effect of Ionomer Layer (Product Selectivity and Reaction Efficiency Test at pH=3) Electrodes prepared according to the methods of Example 1 and Comparative Example 3 were used as cathodes, and titanium mesh loaded with iridium oxide was used as anode. A 0.1 mol / L K₂SO₄ solution (pH adjusted to 3 with H₂SO₄) was used as the electrolyte. Carbon dioxide was continuously passed through at a flow rate of 30 sccm, and different current densities were applied. The Faraday efficiency (FE) of hydrogen and carbon monoxide was measured, and the results are as follows: Figure 3 and Figure 6 As shown ( Figure 3 and Figure 6In the text, "Ag-Hex" indicates the electrode used in Comparative Example 3, and "Ag-IMD" indicates the electrode used in Example 1. The results show that, compared to the electrode using a polyarylpiperidine resin ionomer layer (Comparative Example 3), covering the catalyst layer surface with a polyarylimidazolium resin ionomer layer (Example 1) exhibits a significantly improved ability to mitigate the competitive hydrogen evolution reaction, an advantage that is maintained even under high current density conditions. The reason for this is that the polyaryl main chain of the polyarylimidazolium resin has strong rigidity, which restricts the mobility of the polyarylimidazolium molecular chain, thus providing a stable structural basis for the synergistic effect between the polyarylimidazolium resin and the perfluorosulfonic acid resin.

[0065] Test Example 5: Effect of Ionomer Layer (Product Selectivity and Reaction Efficiency Test at pH=3) Electrodes prepared according to the methods in Example 1 and Comparative Example 4 were used as cathodes, and titanium mesh loaded with iridium oxide was used as anode. A 0.1 mol / L K₂SO₄ solution (pH adjusted to 3 with H₂SO₄) was used as the electrolyte. Carbon dioxide was continuously passed through at a flow rate of 30 sccm, and different current densities were applied. The Faraday efficiency (FE) of hydrogen and carbon monoxide was measured, and the results are as follows: Figure 3 and Figure 7 As shown ( Figure 3 and Figure 7 In the text, "Ag-PS" indicates the electrode used in Comparative Example 4, and "Ag-IMD" indicates the electrode used in Example 1. The results show that when polystyrene resin is used as the ionomer in the catalyst layer (Comparative Example 4), the selectivity for carbon monoxide products at high current densities significantly decreases; however, replacing the polystyrene resin with perfluorosulfonic acid resin (Example 1) not only effectively suppresses the hydrogen evolution side reaction but also increases the carbon monoxide selectivity to over 70%. The reason for this is that perfluorosulfonic acid resin utilizes its sulfonic acid groups to efficiently transport protons, which, combined with the imidazolium cations in the polyarylimidazolium resin, facilitates the transport of H+. + The repulsive effect between the two leads to the formation of an ion pair that can accelerate H+. + By moving away from the substrate layer and the area near the catalyst, H can be better avoided. + It accepts electrons at the electrode and is converted into H2, thus inhibiting the competitive hydrogen evolution reaction.

[0066] Test Example 6: The effect of the ionomer layer (electrode stability test) Electrodes prepared according to the methods of Example 1 and Comparative Example 1 were used as cathodes, and titanium mesh loaded with iridium oxide was used as anode. A 0.1 mol / L K₂SO₄ solution (pH adjusted to 3 with H₂SO₄) was used as electrolyte. Carbon dioxide was continuously introduced at a flow rate of 30 sccm, and a current density of 200 mA / cm⁻¹ was applied. 2The potential and the Faraday efficiency (FE) of carbon monoxide were measured at regular intervals, and the results were as follows: Figure 8 and Figure 9 As shown ( Figure 8 and Figure 9 The results are shown for Comparative Example 1 and Example 1, respectively. The results showed that the electrode without the ionomer layer (Comparative Example 1) deactivated after 3 hours of continuous operation, exhibiting poor stability; the electrode with the ionomer layer covering the catalyst layer (Example 1) maintained high carbon monoxide selectivity for 30 hours (the average carbon monoxide selectivity was over 80% during 30 hours of operation), and the catalyst surface morphology after long-term operation was similar to that at the beginning, demonstrating good stability.

Claims

1. An electrode for electrocatalytic carbon dioxide reduction, characterized in that, It includes a substrate layer, a catalyst layer, and an ionomer layer arranged sequentially; the catalyst layer includes catalyst particles and perfluorosulfonic acid resin; the ionomer layer includes polyarylimidazolium resin.

2. The electrode according to claim 1, characterized in that, The catalyst particles are silver nanoparticles.

3. The electrode according to claim 1 or 2, characterized in that, The mass ratio of the catalyst particles to the perfluorosulfonic acid resin is 20~100:1; the loading of the catalyst particles in the electrode is 1.8~2.2 mg / cm³. 2 .

4. The electrode according to claim 1, characterized in that, The substrate layer is carbon paper.

5. A method for preparing an electrode according to any one of claims 1 to 4, characterized in that, include: S1: A dispersion containing catalyst particles and perfluorosulfonic acid resin is coated onto the surface of the substrate layer and dried to form a catalyst layer; S2: Coat the surface of the catalyst layer with a polyarylimidazolium resin solution and let it stand to obtain the electrode.

6. The preparation method according to claim 5, characterized in that, In step S1, the dispersion medium in the dispersion is anhydrous ethanol; in step S2, the solvent in the polyaryl imidazole resin solution is methanol.

7. The preparation method according to claim 5 or 6, characterized in that, In step S1, the content of catalyst particles in the dispersion is 0.005~0.015 g / mL; in step S2, the content of polyarylimidazolium resin in the polyarylimidazolium resin solution is 0.1~5 wt%.

8. The application of the electrode according to any one of claims 1 to 4 in the electrocatalytic reduction of CO2 to CO, characterized in that, The electrocatalytic reduction of CO2 to CO is carried out under acidic conditions.

9. The application according to claim 8, characterized in that, In the process of electrocatalytic CO2 reduction to CO, the cathode is the electrode, the anode is a titanium mesh loaded with iridium oxide, and the electrolyte is a sulfate solution.

10. The application according to claim 9, characterized in that, The electrolyte contains 0.1–0.15 mol / L of sulfate and has a pH of 1–3; the electrocatalytic reduction of CO2 to CO process uses a current density of 20–300 mA / cm². 2 The CO2 flow rate is 30~40 sccm.

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