Preparation and application of a heat-activated modified polyaniline supported cuprous oxide monolithic electrode

Abstract

The present application relates to a kind of preparation and application of heat-activated polyaniline modified cuprous oxide monolithic electrode, a kind of modified polyaniline load metal organic framework derived cuprous oxide electrode.The above-mentioned monolithic electrode is mainly composed of modified Cu-BTC and polyaniline composite.The metal organic framework can avoid the problem that cuprous oxide is reduced in electro-reduction reaction, and by low-temperature activation method, the polyaniline intermediate layer synthesized by electrodeposition is activated, and divalent copper is reduced to cuprous oxide, to enhance the combination of cuprous oxide and conductive substrate.The electrode is used as the cathode of electrocatalytic reaction, mainly applied to the field of carbon dioxide reduction technology.The raw material provided by the present application is easy to obtain, and the price is low, which overcomes the disadvantages that the active sites of traditional powder catalyst are masked and fall off.The preparation method of the electrode is simple, and stable and efficient carbon dioxide reduction effect is realized.

Description

Technical Field

[0001] This application relates to the field of electrochemical reduction technology, specifically to the preparation of a thermally activated polyaniline-modified cuprous oxide nanoparticle monolithic electrode for the electrocatalytic reduction of carbon dioxide. Technical Background

[0002] Converting carbon dioxide into high-value chemicals can effectively alleviate the dual pressures of increasing greenhouse gas emissions and energy demand. Compared with other technologies, carbon dioxide electrocatalytic reduction technology, as a highly promising carbon-negative technology, utilizes renewable electricity to drive the reaction, converting carbon dioxide into carbon-based fuels, achieving energy storage and utilization, and improving energy consumption levels. Because carbon dioxide molecules are stable, activating CO2 to CO2... -· Overcoming significant energy barriers is crucial. The carbon dioxide reduction process involves multi-electron proton conversion, resulting in poor product selectivity and limiting industrial production. Therefore, developing stable and efficient electrocatalysts is a key and challenging issue in the electrocatalysis of carbon dioxide.

[0003] Copper-based catalysts, with their unique electronic structure and abundant valence states, have attracted widespread attention for their ability to generate valuable hydrocarbons during the electrochemical reduction of carbon dioxide. However, due to its unique structure, metallic copper often undergoes uncontrollable reconstruction processes during electrochemical reactions, making it difficult to maintain the pre-designed active site structure and leading to reduced catalytic activity. Therefore, the coordination of organic ligands within copper metal-organic frameworks can effectively protect the active sites from degradation.

[0004] Furthermore, traditional copper-based catalyst electrodes involve the addition of large amounts of binders during preparation, leading to catalyst agglomeration and blockage of internal active sites, thus reducing catalytic activity. Compared to powdered catalysts, in-situ deposition of catalytic components onto a conductive substrate eliminates the need for additional binders and conductive agents, accelerating charge transfer rates and improving catalytic efficiency. Due to the relatively large particle size of Cu-BTC, direct chemical deposition results in low catalyst loading; therefore, an intermediate layer is introduced to address this loading issue. Polyaniline is a common conductive material; the amine groups in the polymer can complex with copper ions, facilitating increased copper ion loading. While altering acid concentration typically enhances the conductivity of polyaniline, pyrolysis activation of polyaniline to improve conductivity and simultaneously modify cuprous oxide is not commonly observed. This study first deposits polyaniline using electrodeposition, then deposits Cu-BTC onto the polyaniline surface using in-situ deposition, followed by low-temperature activation of the polyaniline to reduce divalent copper ions to cuprous oxide. Summary of the Invention

[0005] To address the poor stability of existing copper-based electrocatalysts, a method for preparing a monolithic electrode of thermally activated polyaniline-modified cuprous oxide nanoparticles for the electrocatalytic reduction of carbon dioxide is provided. This method utilizes polyaniline as an interlayer to increase the loading of the copper-based catalyst on the conductive substrate, thereby increasing the number of active sites and enhancing carbon dioxide conversion performance. The coordination effect within the metal-organic framework prevents Cu... 2+ The problem of reduction in electrochemical reactions needs to be addressed to improve the stability of the catalyst.

[0006] This invention employs a method for preparing a monolithic electrode of thermally activated polyaniline-modified cuprous oxide nanoparticles for the electrocatalytic reduction of carbon dioxide. The preparation steps of this method are as follows:

[0007] Preparation of S1 polyaniline / carbon paper:

[0008] The carbon paper is pretreated to obtain clean carbon paper;

[0009] The acid is diluted in an aqueous solution, and a certain volume of aniline is ultrasonically mixed with the acid solution to obtain an aniline electrolyte solution. The carbon paper treated as described above is immersed in the electrolyte solution, electrodeposited on the cathode, washed with deionized water and dried to obtain polyaniline / carbon paper;

[0010] Preparation of S2 polyaniline / carbon paper-supported Cu-BTC:

[0011] Weigh a certain mass of pyromellitic acid and dissolve it in an ethanol solution, then sonicate to dissolve it.

[0012] Weigh out a certain mass of copper acetate and dissolve it in water to form a copper acetate solution. Place the solution in an environment of 50-100℃ and stir. Then cool the solution to room temperature.

[0013] The prepared polyaniline / carbon paper was placed vertically in the above solution, and a certain mass of polyvinylpyrrolidone was added. Then, pyromellitic acid solution was slowly poured into the mixture and stirred at room temperature. A Cu-BTC layer was uniformly grown on the surface of the polyaniline / carbon paper. After rinsing the electrode, it was dried at 60°C for 12 hours.

[0014] S3 Low-temperature activated polyaniline / carbon paper supported cuprous oxide monolithic electrode:

[0015] The electrode with Cu-BTC uniformly loaded on the surface of the above polyaniline / carbon paper was calcined under a nitrogen atmosphere to obtain a monolithic polyaniline / carbon paper loaded cuprous oxide electrode.

[0016] Furthermore, in step S1, the carbon paper pretreatment step is as follows: [The text abruptly shifts to a seemingly unrelated topic about carbon paper pretreatment.] 2 The carbon paper was placed in a methanol solution and sonicated for 20 minutes, then placed in distilled water and sonicated for 20 minutes. This washing process was repeated three times.

[0017] Optionally, in step S1, the acid includes one or more of sulfuric acid, hydrochloric acid, and phosphoric acid, with an acid concentration of 0.5-1.5 mol / L, and the volume of aniline is 1 mol / L. The acid is added to 13.5 mL of aniline solution.

[0018] Optionally, in step S1, the electrolyte solution is electrodeposited in the aniline electrolyte solution to obtain polyaniline / carbon paper. The deposition conditions include: initial voltage of 0.5-1.3V, deposition time of 50-400s, sampling interval of 0.1s, and sensitivity of 1×10⁻⁶. -1 A, the settling time is 0 seconds;

[0019] Optionally, the mass of pyromellitic acid in step S2 is 0.1-0.4g.

[0020] Optionally, in step S2, the mass of copper acetate is 0.2-1.5g, the stirring time is 1-4h, and the mass of polyvinylpyrrolidone is 0.05-0.75g.

[0021] Optionally, in step S3, the nitrogen flow rate is 2-5 mL, the calcination temperature is 200-400℃, the heating rate is 3-10℃ / min, and the calcination reaction time is 2-4 h.

[0022] Beneficial effects: This invention provides a method for preparing a monolithic electrode of thermally activated polyaniline-modified cuprous oxide nanoparticles for the electrocatalytic reduction of carbon dioxide. This method has the following advantages:

[0023] S1 uses an in-situ deposition method to grow Cu-based catalysts on the catalyst surface to prepare electrocatalytic carbon dioxide reduction electrodes. This avoids the use of additional binders and conductive agents, which can prevent material detachment caused by the addition of binders and reduce the cost of electrode preparation.

[0024] S2 utilizes the complexation between the polyaniline layer and copper ions to increase the loading of copper ions on the conductive substrate, thereby increasing the number of catalytically active ions and improving the catalytic efficiency of the electrocatalytic electrode. Attached Figure Description

[0025] Figure 1 A flowchart of the preparation method provided for an example of the present invention;

[0026] Figure 2 Scanning electron microscope image of a monolithic electrode made of thermally activated polyaniline-modified cuprous oxide nanoparticles, provided as an example of the present invention;

[0027] Figure 3 The image shows the Faraday efficiency of a monolithic electrode made of thermally activated polyaniline-modified cuprous oxide nanoparticles. Detailed Implementation

[0028] Example 1: Preparation method of monolithic electrode made of thermally activated polyaniline-modified cuprous oxide nanoparticles

[0029] The carbon paper was pretreated to obtain clean carbon paper. 54 mL of sulfuric acid was diluted in 1 L of deionized water. 13.5 mL of aniline was ultrasonically mixed with the sulfuric acid solution to obtain an aniline electrolyte solution. The pretreated carbon paper was then immersed in the electrolyte solution, and electrodeposition was performed on the cathode. The electrodeposition conditions were: initial voltage 1 A, deposition time 100 s, sampling interval 0.1 s, and sensitivity 1 × 10⁻⁶. -1 A. After standing for 0 seconds, washing and drying with deionized water, polyaniline / carbon paper is obtained.

[0030] Weigh 0.2g of trimesic acid and dissolve it in an ethanol solution, then sonicate to dissolve. Weigh 0.2g of copper acetate and dissolve it in water to form a copper acetate solution. Place the above solution in a 100°C environment and stir. Then cool the above solution to room temperature.

[0031] The prepared polyaniline / carbon paper was placed vertically in the above solution, and 0.1g of polyvinylpyrrolidone was added. Then, pyromellitic acid solution was slowly poured into the mixture and stirred at room temperature. A Cu-BTC layer was uniformly grown on the surface of the polyaniline / carbon paper. After rinsing the electrode, it was dried at 60°C for 12h.

[0032] The electrode with Cu-BTC uniformly loaded on the surface of the above polyaniline / carbon paper was calcined at 250°C for 2 hours under a nitrogen atmosphere to obtain a monolithic polyaniline / carbon paper-loaded cuprous oxide electrode.

[0033] Example 2: Preparation method of monolithic electrode made of thermally activated polyaniline-modified cuprous oxide nanoparticles

[0034] The difference between this embodiment and Example 1 is the different polyaniline deposition time;

[0035] The carbon paper was pretreated to obtain clean carbon paper. 54 mL of sulfuric acid was diluted in 1 L of deionized water, and 13.5 mL of aniline was ultrasonically mixed with the sulfuric acid solution to obtain an aniline electrolyte solution. The pretreated carbon paper was immersed in the electrolyte solution, and electrodeposition was performed on the cathode under the following conditions: initial voltage of 1 A, deposition time of 50 s, sampling interval of 0.1 s, and sensitivity of 1 × 10⁻⁶. -1 A. After standing for 0 seconds, washing and drying with deionized water, polyaniline / carbon paper is obtained.

[0036] Weigh 0.2g of trimesic acid and dissolve it in an ethanol solution, then sonicate to dissolve. Weigh 0.2g of copper acetate and dissolve it in water to form a copper acetate solution. Place the above solution in a 100°C environment and stir. Then cool the above solution to room temperature.

[0037] The prepared polyaniline / carbon paper was placed vertically in the above solution, and 0.1g of polyvinylpyrrolidone was added. Then, pyromellitic acid solution was slowly poured into the mixture and stirred at room temperature. A Cu-BTC layer was uniformly grown on the surface of the polyaniline / carbon paper. After rinsing the electrode, it was dried at 60°C for 12h.

[0038] The electrode with Cu-BTC uniformly loaded on the surface of the above polyaniline / carbon paper was calcined at 250°C for 2 hours under a nitrogen atmosphere to obtain a monolithic polyaniline / carbon paper-loaded cuprous oxide electrode.

[0039] Example 3: Preparation method of monolithic electrode made of thermally activated polyaniline-modified cuprous oxide nanoparticles

[0040] The difference between this embodiment and Example 2 is that the pyrolysis temperature of polyaniline is different.

[0041] The carbon paper was pretreated to obtain clean carbon paper. 54 mL of sulfuric acid was diluted in 1 L of deionized water. 13.5 mL of aniline was ultrasonically mixed with the sulfuric acid solution to obtain an aniline electrolyte solution. The pretreated carbon paper was then immersed in the electrolyte solution, and electrodeposition was performed on the cathode. The electrodeposition conditions were: initial voltage 1 A, deposition time 50 s, sampling interval 0.1 s, and sensitivity 1 × 10⁻⁶. -1 A. After standing for 0 seconds, washing and drying with deionized water, polyaniline / carbon paper is obtained.

[0042] Weigh 0.2g of pyromellitic acid and dissolve it in an ethanol solution, then sonicate to dissolve it. Weigh 0.2g of copper acetate and dissolve it in water to form a copper acetate solution. Place the above solution in a 100°C environment and stir. Then cool the above solution to room temperature.

[0043] The prepared polyaniline / carbon paper was placed vertically in the above solution, and 0.1g of polyvinylpyrrolidone was added. Then, pyromellitic acid solution was slowly poured into the mixture and stirred at room temperature. A Cu-BTC layer was uniformly grown on the surface of the polyaniline / carbon paper. After rinsing the electrode, it was dried at 60°C for 12h.

[0044] The electrode with Cu-BTC uniformly loaded on the surface of the above polyaniline / carbon paper was calcined at 350°C for 2 hours under a nitrogen atmosphere to obtain a monolithic polyaniline / carbon paper-loaded cuprous oxide electrode.

[0045] Example 4: Preparation method of monolithic electrode made of thermally activated polyaniline-modified cuprous oxide nanoparticles

[0046] The difference between this embodiment and Example 3 is the different mass of polyvinylpyrrolidone in the Cu-BTC synthesis;

[0047] The carbon paper was pretreated to obtain clean carbon paper. 54 mL of sulfuric acid was diluted in 1 L of deionized water. 13.5 mL of aniline was ultrasonically mixed with the sulfuric acid solution to obtain an aniline electrolyte solution. The pretreated carbon paper was then immersed in the electrolyte solution, and electrodeposition was performed on the cathode. The electrodeposition conditions were: initial voltage 1 A, deposition time 100 s, sampling interval 0.1 s, and sensitivity 1 × 10⁻⁶. -1 A. After standing for 0 seconds, washing and drying with deionized water, polyaniline / carbon paper is obtained.

[0048] Weigh 0.2g of pyromellitic acid and dissolve it in an ethanol solution, then sonicate to dissolve it. Weigh 0.2g of copper acetate and dissolve it in water to form a copper acetate solution. Place the above solution in a 100°C environment and stir. Then cool the above solution to room temperature.

[0049] The prepared polyaniline / carbon paper was placed vertically in the above solution, and 0.05g of polyvinylpyrrolidone was added. Then, pyromellitic acid solution was slowly poured into the mixture and stirred at room temperature. A Cu-BTC layer was uniformly grown on the surface of the polyaniline / carbon paper. After rinsing the electrode, it was dried at 60°C for 12h.

[0050] The electrode with Cu-BTC uniformly loaded on the surface of the above polyaniline / carbon paper was calcined at 350°C for 2 hours under a nitrogen atmosphere to obtain a monolithic polyaniline / carbon paper-loaded cuprous oxide electrode.

[0051] Experimental Example 1

[0052] The electrode prepared in Example 2 was used to test the electrocatalytic carbon dioxide reduction performance. The cathode was the prepared monolithic electrode, the anode was a platinum sheet electrode, and the reference electrode was an Ag / AgCl electrode. The electrochemical reaction was carried out in an H-type reactor, with the cathode and anode chambers separated by a proton exchange membrane. Before the reaction, carbon dioxide gas was continuously introduced into the cathode chamber for 40 minutes. The results of the electrocatalytic reduction reaction were as follows: Figure 3 As shown.

[0053] Depend on Figure 3 It can be seen that the monolithic electrode prepared in Example 2 has a good carbon dioxide reduction effect. Specifically, when the voltage is -0.98V vs. RHE, the Faraday efficiency of ethylene can reach 38%.

Claims

1. A method for preparing a hot-activated polyaniline modified cuprous oxide nanoparticle monolithic electrode for electrocatalytic reduction of carbon dioxide, comprising the following steps: S1.Preparation of polyaniline / carbon paper The carbon paper is pretreated to obtain clean carbon paper. An acid is diluted in an aqueous solution, a certain volume of aniline is ultrasonically mixed with the acid solution to obtain an aniline electrolyte solution, the above-processed carbon paper is immersed in the electrolyte solution, and electrodeposition is performed on the cathode, and then the electrode is washed and dried with deionized water to obtain polyaniline / carbon paper. S2.Preparation of polyaniline / carbon paper loaded with Cu-BTC A certain mass of trimesic acid is dissolved in an ethanol solution and ultrasonically dissolved. A certain amount of copper acetate is dissolved in water to form a copper acetate solution. The solution is stirred in a C environment and cooled to room temperature. o C environment and cooled to room temperature. The prepared polyaniline / carbon paper was vertically placed in the above solution, a certain mass of polyvinylpyrrolidone was added, then the solution of trimesic acid was slowly poured into the mixture, stirred at room temperature, and a layer of Cu-BTC was uniformly grown on the surface of the polyaniline / carbon paper. After washing, 60 o C dried for 12 h; S3.Low-temperature activated polyaniline / carbon paper loaded cuprous oxide monolithic electrode The polyaniline / carbon paper uniformly loaded with Cu-BTC is calcined under a nitrogen atmosphere, the calcination temperature is 200-350 o C, the temperature rising rate is 3-10 o C / min, the flow rate of nitrogen is 2-5 mL / min, the calcination reaction time is 2-4 h, to obtain a polyaniline / carbon paper loaded cuprous oxide monolithic electrode.

2. The method for preparing the monolithic electrode of thermally activated polyaniline-modified cuprous oxide nanoparticles according to claim 1, characterized in that, In the step S1, the acid includes one or more of sulfuric acid, hydrochloric acid, and phosphoric acid, the acid concentration is 0.5-1.5 mol / L, and the volume of aniline is 6-21 mL.

3. The method of claim 1, wherein the heat-activated polyaniline-modified cuprous oxide nanoparticle monolithic electrode is prepared by the steps of: (a) preparing a mixture of cuprous oxide nanoparticles and a polyaniline precursor; (b) mixing the mixture with a binder; (c) coating the mixture on a substrate; (d) drying the mixture; (e) heating the mixture; and (f) removing the binder. The electrodeposition conditions in the step S1 include: initial voltage of 0.5-1.3 A, deposition time of 50-400 s, sampling interval of 0.1 s, sensitivity of 1x10 -1 A, and standing time of 0 s.

4. The method for preparing the monolithic electrode of thermally activated polyaniline-modified cuprous oxide nanoparticles according to claim 1, characterized in that, In the step S2, the mass of trimesic acid is 0.1-0.4 g.

5. The method for preparing the monolithic electrode of thermally activated polyaniline-modified cuprous oxide nanoparticles according to claim 1, characterized in that, In the step S2, the mass of copper acetate is 0.2-1.5 g, the stirring time is 1-4 h, and the mass of polyvinylpyrrolidone is 0.05-0.75 g.

6. A hot activated polyaniline modified cuprous oxide nanoparticle monolithic electrode prepared according to the method of any one of claims 1 to 5, characterized by: The hot-activated polyaniline modified cuprous oxide nanoparticle monolithic electrode is used for electrocatalytic reduction of carbon dioxide.

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