A copper-carbon composite electrode and a preparation method and application thereof

Abstract

The application relates to the technical field of electrochemical mediation carbon dioxide capture, in particular to a copper-carbon composite electrode and a preparation method and application thereof. The method comprises the following steps: taking a carbon substrate as a working electrode, and performing electrodeposition in an electrolyte configured by a copper complex solution and a composite buffer solution; the composite buffer solution comprises sodium dihydrogen phosphate, boric acid and polyethylene glycol; the average molecular weight of the polyethylene glycol is 200-2000 g / mol, and the complexing agent in the copper complex solution is citrate. The application can accelerate the cathode reaction rate, is beneficial to the electrochemical reaction, reduces the cost of a pure copper electrode, and improves the corrosion resistance and operation stability of the electrode. When the electrode is applied to an electrochemical mediation amine-based regenerated CO2 capture system, the reaction rates of the anode and the cathode can be simultaneously accelerated, and the electrochemical reaction is promoted.

Description

Technical Field

[0001] This invention relates to the field of electrochemically mediated carbon dioxide capture technology, and in particular to a copper-carbon composite electrode, its preparation method, and its application. Background Technology

[0002] Electrochemically mediated amine regeneration technology, as a highly efficient carbon dioxide capture method, has been widely studied and applied in recent years due to its advantages such as low energy consumption, mild operating conditions, and modular design. In this technology, an amine solution is used to absorb carbon dioxide, which is then released from the amine solution through an electrochemical process, thus achieving the regeneration and recycling of the amine solution. In this process, copper ions, as a widely used active medium, play a crucial role in promoting the CO2 desorption reaction. The high complexing ability and moderate redox properties of copper ions enable them to effectively combine with organic amines to form stable complexes, thereby achieving rapid dissociation and release of CO2. Furthermore, copper complex ions in the solution can be reduced at the cathode surface, further regenerating the organic amine solution. The stability of copper ions and the controllability of the reaction are crucial to ensuring the efficiency and stability of the entire reaction system.

[0003] In the electrolysis system, the pure copper electrode at the anode is the direct source of copper ions. Since this electrode does not release other impurity ions, it effectively reduces the occurrence of side reactions and ensures high selectivity for the CO2 release process. In addition, copper, as a relatively inexpensive and abundant metal material, has excellent conductivity and easy processing properties, making it a commonly used electrode material in electrochemical reactions. Despite the above advantages, pure copper electrodes exhibit a series of limiting problems in practical applications. (1) Mass transfer is limited, and the reaction rate is slow. Pure copper electrodes usually have a flat or dense structure, and the copper particles are relatively large, which results in a smaller number of active sites for electrochemical reactions. At the same time, this planar electrode shape hinders the diffusion of reactants in the electrolyte, making it difficult for copper ions to be released at the anode and unfavorable for copper deposition at the cathode, resulting in a relatively slow overall reaction process. (2) Under high temperature and electrochemical conditions, amine solutions may exacerbate the corrosion of copper electrodes, especially in environments containing oxidizing impurities or operating for a long time, where copper electrodes are easily oxidized or dissolved. (3) The cost is high. The preparation process of pure copper metal electrodes is complex, and they are prone to corrosion and degradation during the reaction process, leading to frequent replacements and increasing costs.

[0004] To address the aforementioned problems with pure copper electrodes, the design and development of a novel electrode has become a key requirement in the field of electrochemically mediated amine regeneration technology. To meet the high performance requirements of the system, the novel electrode needs to possess the following characteristics: (1) Small copper particle size: By loading finer copper particles onto a corrosion-resistant substrate, the number of catalytically active sites on its surface can be significantly increased, thereby greatly accelerating the electrode's reaction process. (2) Strong corrosion resistance: The novel electrode should be composited with a highly corrosion-resistant material (such as a carbon-based substrate or a metal alloy) to enhance the long-term stability and durability of the electrode. (3) By preparing a composite electrode, the amount of Cu used can be reduced, and the synthesis method is simple, facilitating large-scale synthesis and maximizing economic benefits. Patent application CN117888160A discloses a copper-carbon composite material and its preparation method, the electrode, and its application. Its synthesis process involves adding a specific ionic liquid to the cathode electrolyte and then electrodepositing it onto a carbon substrate to form copper oxide modified with the ionic liquid. This method generates a large amount of copper oxide during the reaction, which is precisely what the electrochemically mediated amine regeneration system aims to reduce, thus limiting its application in this reaction to some extent. Patent application CN116145193A discloses a copper-based catalyst for the electrocatalytic reduction of nitrate to ammonia and its preparation method. The electrodeposition solution is prepared by dissolving CuSO4·5H2O, AgNO3, and NaOH in a mixture of ethanol and water. Finally, the electrodeposited carbon cloth is sintered to obtain Cu... x O / Ag-CC heterojunction electrode material. Although copper-based materials are deposited on the carbon substrate surface, the fusion of copper and carbon materials is insufficient, making it unsuitable for application in electrochemically mediated amine regeneration systems. Furthermore, this method is relatively complex in its procedures, and the use of precious metals such as Ag results in high costs, hindering large-scale synthesis.

[0005] Therefore, developing novel copper-based composite electrodes to replace traditional pure copper electrodes, and optimizing the design and manufacturing methods of anodic copper-based composite electrodes, enables environmentally friendly, economical, and scalable synthesis. The widespread application of high-performance copper-based composite electrodes will further promote the development of electrochemical CO2 capture technology and accelerate its industrial application. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a method for preparing a copper-carbon composite electrode in an electrochemically mediated amine regeneration system and its application. The copper-carbon composite electrode provided by this invention solves the problem of slow electrode reaction processes in the prior art, accelerates the cathode reaction rate, facilitates the electrochemical reaction, reduces the cost of pure copper electrodes, and improves the electrode's corrosion resistance and operational stability. Applying this electrode to an electrochemically mediated amine regeneration CO2 capture system can simultaneously accelerate the reaction rates of both the anode and cathode, promoting the electrochemical reaction.

[0007] In a first aspect, the present invention provides a method for preparing a copper-carbon composite electrode, comprising: using a carbon substrate as the working electrode, and performing electrodeposition in an electrolyte prepared from a copper complex solution and a composite buffer solution; wherein the composite buffer solution comprises sodium dihydrogen phosphate, boric acid, and polyethylene glycol; the average molecular weight of the polyethylene glycol is 200-2000 g / mol, and the complexing agent in the copper complex solution is citrate. In this invention, electrodeposition technology is employed, and by optimizing the composition of the electrolyte and the electrodeposition process, a copper-carbon composite layer is deposited on a carbon substrate to form a copper-carbon composite electrode. The optimized composition of the electrolyte is crucial for improving electrode performance, effectively reducing the size of copper particles in the copper-carbon composite electrode and promoting the electrochemical reaction of the electrode. Furthermore, the introduction of carbon into the copper-carbon composite layer not only reduces the cost of pure copper electrodes but also improves the corrosion resistance and operational stability of the electrode.

[0008] Preferably, in the composite buffer solution, the concentration of sodium dihydrogen phosphate is 0.01~2.0 mol / L, preferably 0.2~0.6 mol / L, more preferably 0.4±0.1 mol / L; the concentration of boric acid is 0.01~5 mol / L, preferably 0.4~1.2 mol / L, more preferably 0.8±0.1 mol / L; the concentration of polyethylene glycol is 0.1~50 mg / L, preferably 8~12 mg / L, more preferably 10±0.2 mg / L; and the average molecular weight of polyethylene glycol is 400~1000 g / mol, more preferably 400~800 g / mol. And / or, the concentration ratio of sodium dihydrogen phosphate, boric acid, and polyethylene glycol is 0.4~0.8 mol / L : 0.8~1.2 mol / L : 9.5~10 mg / L.

[0009] In this invention, optimizing the ratio of sodium dihydrogen phosphate, boric acid, and polyethylene glycol enhances the wetting effect of the electrolyte on the electrode surface, effectively suppressing the electrochemical polarization of the deposited copper protrusions and thus inhibiting copper grain deposition, thereby achieving grain refinement of the copper-carbon composite electrode. Simultaneously, sodium dihydrogen phosphate, boric acid, and polyethylene glycol exhibit better interactions, resulting in synergistic effects in improving electrode surface leveling, eliminating pinholes in the plating, and enhancing plating uniformity.

[0010] Preferably, the copper complex solution is prepared by mixing a copper salt solution with the complexing agent.

[0011] Further preferably, the copper salt solution is a copper sulfate solution or a copper nitrate solution, preferably a copper sulfate solution; the complexing agent is sodium citrate or potassium citrate, preferably sodium citrate; and the concentration of the copper sulfate solution is 0.01~0.2 mol / L, preferably 0.06±0.02 mol / L.

[0012] Further preferably, the amount of citrate added is 1 to 3 times the molar amount of the copper salt, preferably 2 ± 0.5 times.

[0013] Preferably, the preparation method of the copper-carbon composite electrode further includes adjusting the pH value of the electrolyte to 6.5-7.5 using an alkaline solution, preferably 7.0-7.5, such as 7.2, 7.4, 7.5, etc. Using the preferred electrolyte pH value can better ensure the deposition effect.

[0014] Preferably, the alkaline solution comprises one or more of sodium hydroxide, potassium hydroxide, and ammonia water, and is preferably a 0.5±0.1 mol / L potassium hydroxide solution.

[0015] Preferably, the carbon substrate is selected from one or more of graphite paper, carbon paper, carbon cloth, and carbon foam, with graphite paper being the most preferred.

[0016] Further preferably, the method for preparing the copper-carbon composite electrode includes: 1) Preparation of copper complex solution: Mix copper sulfate solution with citrate and stir to obtain copper complex solution.

[0017] 2) Preparation of composite buffer solution: Sodium dihydrogen phosphate, boric acid, polyethylene glycol and water are mixed and stirred to obtain composite buffer solution.

[0018] 3) Preparation of electrolyte: Mix the composite buffer solution and the copper complex solution, stir, adjust the pH value and preheat to obtain the electrolyte.

[0019] 4) Preparation of copper-carbon composite electrode: Using a carbon substrate as the working electrode and the electrolyte as the electrolyte, a negative potential is applied to the carbon electrode and electrodeposition is performed to obtain a copper-carbon composite electrode. This invention employs optimized electrodeposition technology. By optimizing the electrolyte composition and electrodeposition process, a copper-carbon composite layer is better deposited on the carbon substrate to form a copper-carbon composite electrode. Based on the optimized electrolyte composition and specific electrodeposition parameters, the size of copper particles in the copper-carbon composite electrode can be effectively reduced, promoting the electrochemical reaction of the electrode. The introduction of polyethylene glycol and sodium citrate into the copper-carbon composite layer facilitates the adsorption of these substances onto the surface of the electrolytic copper, promoting the formation of spherical clusters, increasing cathode polarization, and thus reducing surface tension. This results in a finer crystallization of the coating, further improving the electrode's corrosion resistance, catalytic efficiency, activity, and operational stability.

[0020] Preferably, in steps 1) and 2), nitrogen-saturated deionized water is used to prepare the solution. Using nitrogen-saturated deionized water can better ensure the quality of copper ion particles and greatly reduce the formation of copper oxides.

[0021] Preferably, in step 3), the composite buffer solution is added to the copper complex solution at a rate of 1~10 mL / min, such as 2 mL / min, 3 mL / min, 4 mL / min, 5 mL / min, 6 mL / min, 7 mL / min, 8 mL / min, etc., preferably 5±0.5 mL / min.

[0022] Preferably, in step 3), the preheating temperature is 30~90℃, more preferably 40~80℃, such as 40℃, 50℃, 60℃, 70℃, 80℃, etc., and more preferably 65±2℃. This invention enhances the reactivity of the solution by preheating the electrolyte.

[0023] Preferably, in step 3), the pH value is adjusted to 6.5~7.5, more preferably 7.0~7.5, and even more preferably 7.2~7.5, such as 7.2, 7.3, 7.4, 7.5, etc.

[0024] Further preferably, in step 4), the negative potential is -0.01 to -1.5 V, such as -0.1 V, -0.3 V, -0.5 V, -0.8 V, -1 V, -1.3 V, etc., preferably -0.5 to -1.2 V, more preferably -1.0 to -1.2 V, and the electrodeposition time is 0.1 to 600 min, preferably 20 to 60 min, more preferably 40 to 60 min, such as 42 min, 45 min, 48 min, 50 min, 55 min, 58 min, etc. By using a specific electrolyte as the electrolyte, applying a certain negative potential to the working electrode of the carbon substrate, and controlling the preferred deposition conditions to form a uniform copper-carbon composite layer, the highly dispersed copper nanoparticles can significantly improve the active area and catalytic efficiency of the catalyst. If the negative potential of the electrodeposition in this invention is too low, the reduction rate of copper ions will be uneven, easily leading to slow crystal growth; if it is too high, the hydrogen evolution reaction will be severe, resulting in pores on the electrode surface, uneven coating, and affecting the stability of the electrode.

[0025] In this invention, a three-electrode system is used, with a carbon substrate as the working electrode, a platinum sheet electrode as the auxiliary electrode, and a saturated calomel electrode as the reference electrode.

[0026] According to the present invention, the planar dimensions of the carbon substrate can be any size, such as 1 cm × 2 cm, 1.5 cm × 1.8 cm, 2 cm × 2 cm, etc., and the present invention preferably uses 1 cm × 2 cm.

[0027] Secondly, the present invention provides a copper-carbon composite electrode, which is prepared by the aforementioned preparation method.

[0028] Preferably, a copper-carbon composite layer is deposited on the surface of the carbon substrate, exhibiting a relatively rough texture and distributed with many protruding particles of varying sizes. These particles are formed by copper crystallization during the electrodeposition process, with copper nanoparticles embedded in the carbon layer. The particle size of the copper nanoparticles is 10~50 nm, preferably 30 nm.

[0029] Thirdly, this invention provides the application of the copper-carbon composite electrode obtained by the above preparation method or the copper-carbon composite electrode described above, wherein the copper-carbon composite electrode is used as an electrode in an electrochemically mediated amine-regenerated CO2 capture system. During electrolysis, the copper-carbon composite electrode of the working electrode (anode) generates copper ions through an electrochemical reaction. The generated copper ions can further undergo a coordination substitution reaction with the adsorbed saturated carbon dioxide complex, thereby promoting the dissociation of the amine-carbon dioxide complex. Through this process, the release of carbon dioxide and the regeneration of the absorbent are effectively achieved.

[0030] According to a preferred embodiment of the present invention, a copper-carbon composite electrode for an electrochemically mediated amine regeneration system prepared by the aforementioned method is applied in an electrochemically mediated amine regeneration CO2 capture system, with the copper-carbon composite electrode serving as the working electrode and / or counter electrode. The electrolyte contains 0.2–1.5 M ethylenediamine, 0.2–0.8 M potassium sulfate, and 0.2–0.8 M ammonium sulfate, more preferably 0.5 M ethylenediamine, 0.5 M potassium sulfate, and 0.5 M ammonium sulfate. In a further preferred embodiment, the electrolyte is 0.5 M ethylenediamine, 0.5 M potassium sulfate, and 0.5 M ammonium sulfate; the working electrode and counter electrode are the aforementioned copper-carbon composite electrode; the reference electrode is Ag / AgCl; the cyclic voltammetry (CV) test potential is set to -1.2–0.8 V vs. Ag / AgCl, and the scan rate is 0.5–100 mV s. -1 The CV curves of the copper-carbon composite electrode and those of conventional electrodes, such as copper electrodes, were compared in terms of current density. The copper-carbon composite electrode exhibited a larger current density in the cyclic voltammetry test, effectively accelerating the system's reaction.

[0031] The beneficial effects of this invention are at least as follows: 1. Small copper particle size accelerates system reaction: This invention fully utilizes the unique structural advantage of the small copper particle size in the copper-carbon composite electrode. The copper-carbon composite electrode with high active sites can rapidly release copper ions, thereby significantly improving the CO2 release efficiency in the system. The copper-carbon composite electrode provided by this invention exhibits a larger current density in cyclic voltammetry testing, effectively accelerating the system reaction.

[0032] 2. Excellent Electrode Stability and Corrosion Resistance: The copper-carbon composite electrode of this invention utilizes the excellent corrosion resistance of the carbon substrate material itself, and it does not react adversely with copper, avoiding the corrosion problems that occur in traditional Cu electrodes in electrochemically mediated amine regeneration electrolytes. Furthermore, the excellent conductivity of the carbon substrate allows for a more uniform distribution of copper during the deposition process, thereby improving the overall stability of the electrode. Carbon doping in the copper-carbon composite layer can further enhance the material's corrosion resistance.

[0033] 3. Optimized electrode structure further reduces costs: This invention optimizes the electrode structure by using carbon-based materials (such as carbon paper, carbon cloth, graphite paper, etc.) as the skeleton material for copper loading. These carbon-based materials are not only lightweight but also form tight electronic coupling with the deposited copper particles, significantly improving overall conductivity. Due to the carbon doping in the copper-carbon composite layer on the electrode surface, the amount of copper used is effectively reduced, significantly lowering material costs. Furthermore, this design offers good processability and adaptability, further reducing the complexity of the manufacturing process and related costs. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0035] Figure 1 The image shows the XRD pattern of the copper-carbon composite electrode provided in Embodiment 1 of the present invention.

[0036] Figure 2 This is a SEM image of the copper-carbon composite electrode provided in Embodiment 1 of the present invention.

[0037] Figure 3 Cyclic voltammetry was tested in an electrolytic cell for the copper-carbon composite electrode provided in Embodiment 1 of the present invention.

[0038] Figure 4 This is a SEM image of the conventional copper electrode in Comparative Example 1 of the present invention.

[0039] Figure 5 The image shows a cyclic voltammetry diagram of a conventional copper electrode in an electrolytic cell, as shown in Comparative Example 1 of this invention.

[0040] Figure 6 The image shows a cyclic voltammetry diagram of a conventional copper electrode in an electrolytic cell, as shown in Comparative Example 2 of this invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0042] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0043] Unless otherwise specified, the techniques or conditions described in the embodiments of this invention shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Devices, instruments, reagents, etc., without specified manufacturers, are all conventional products that can be purchased through legitimate channels. All experimental reagents and raw materials involved are commercially available products, and all reagents are analytical grade products.

[0044] Example 1 This embodiment provides a copper-carbon composite electrode for use in an electrochemically mediated amine-based regeneration CO2 capture system. The preparation method of this copper-carbon composite electrode is as follows: Step 1: Prepare the copper complex solution. Dissolve copper sulfate in 100 mL of nitrogen-saturated deionized water and stir thoroughly to prepare a 0.06 mol / L copper sulfate solution. Then add sodium citrate as a complexing agent at twice the molar amount of copper sulfate, and continue stirring until the solution is homogeneous.

[0045] Step 2: Prepare the composite buffer solution. Dissolve sodium dihydrogen phosphate, boric acid, and polyethylene glycol sequentially in another 100 mL of nitrogen-saturated deionized water. Ensure complete dissolution and a homogeneous mixture after each addition. The concentrations of sodium dihydrogen phosphate (0.4 mol / L), boric acid (0.8 mol / L), and polyethylene glycol (400 average molecular weight) (10 mg / L) are as follows:

[0046] Step 3: Prepare the electrolyte. Under stirring, slowly add the composite buffer solution to the copper complex solution at a rate of 5 mL / min. Then, adjust the pH of the mixed solution to 7.5 using a 0.5 mol / L sodium hydroxide solution to form a stable electrolyte. Heat the prepared electrolyte to 65°C for later use.

[0047] Step 4: Electrodeposition to prepare a copper-carbon composite electrode. In the three-electrode system, a platinum sheet electrode was used as the auxiliary electrode, a saturated calomel electrode (SCE) as the reference electrode, and a 1 cm × 2 cm graphite paper as the working electrode. The electrolyte prepared in Step 3 was used as the electrolyte, and a potential of -1.0 V vs. SCE was applied to the working electrode. The deposition time was controlled at 45 min to form a uniform copper-carbon composite layer, thus obtaining the final copper-carbon composite electrode.

[0048] Performance Testing: The reaction was tested in a single-port reaction cell at room temperature. The electrolyte consisted of 0.5 M EDA, 0.5 M potassium sulfate, and 0.5 M ammonium sulfate. The working and counter electrodes were copper-carbon electrodes, and the reference electrode was Ag / AgCl. Cyclic voltammetry (CV) was performed at potentials ranging from -1.2 to 0.8 V vs. Ag / AgCl, with scan rates from 0.5 to 100 mV s. -1 . Figure 1 This is the XRD pattern of a copper-carbon composite electrode. The pattern indicates that the catalyst is mainly composed of Cu. Figure 2 This is a SEM image of the copper-carbon composite electrode in Example 1. The image shows a relatively rough surface texture with many protruding particles of varying sizes. These particles are approximately 30 nm copper particles formed during the electrodeposition process, and the coating is relatively uniform. Figure 3 The CV curve of the copper-carbon composite electrode in the electrolytic cell in Example 1 clearly shows that the copper oxidation peak is approximately at 0.3 V vs. Ag / AgCl, with a current density of 118.2 mA cm⁻¹. -2 The reduction peak of copper is at -0.8 V vs. Ag / AgCl, with a current density of -86 mA cm⁻¹. -2 .

[0049] Comparative Example 1 This comparative example provides a copper-carbon composite electrode. The preparation method of this copper-carbon composite electrode includes: in a three-electrode system, using a platinum sheet electrode as the auxiliary electrode, a saturated calomel electrode as the reference electrode, and a 1 cm × 2 cm graphite substrate as the working electrode. A 0.06 mol / L copper sulfate solution is used as the electrolyte, and a potential of -1.0 V vs. SCE is applied to the working electrode, controlling the deposition time to 45 min to form a uniform copper electrode. Figure 4 As can be seen, when only copper sulfate solution is used as the electrolyte, many irregularly shaped copper particles can be seen on the electrode. These particles vary in size, with the Cu size being approximately 3-5 μm. Their surfaces are rough and the coating is unevenly distributed, which is extremely detrimental to the stability of the material. Figure 5 The image shows the CV curve of the copper-carbon composite electrode in the electrolytic cell in Comparative Example 1. As can be seen from the image, the oxidation peak current density of copper is 32.02 mAcm⁻¹. -2At the same time, it was also found that a severe hydrogen evolution reaction occurred at -0.8V vs. Ag / AgCl, which is detrimental to the stability of the system.

[0050] Comparative Example 2 This comparative example provides a copper-carbon composite electrode, which uses the same method as in Example 1, except that the copper complex solution is replaced by copper sulfate solution and sodium citrate is not added. Figure 6 The CV curve for Comparative Example 2 shows that the oxidation peak current density of copper is 35.89 mA cm⁻¹. -2 Compared to Example 1, the difference is significantly smaller. Meanwhile, at -0.8V vs. Ag / AgCl, a severe hydrogen evolution reaction has already occurred.

[0051] Comparative Example 3 This comparative example provides a copper-carbon composite electrode, which uses the same method as in Example 1, except that polyethylene glycol with an average molecular weight of 400 is replaced with polyethylene glycol with an average molecular weight of 4000.

[0052] Performance testing showed that the oxidation peak current density of copper was 54.24 mA cm⁻¹. -2 Compared to Example 1, the value is significantly smaller. Meanwhile, a severe hydrogen evolution reaction has already occurred at -0.8V vs. Ag / AgCl.

[0053] Example 2 This embodiment provides a copper-carbon composite electrode for use in an electrochemically mediated amine-based regeneration CO2 capture system. The preparation method of this copper-carbon composite electrode is as follows: Step 1: Prepare the copper complex solution. Dissolve copper sulfate in 100 mL of nitrogen-saturated deionized water and stir thoroughly to prepare a 0.06 mol / L copper sulfate solution. Then add sodium citrate as a complexing agent at twice the molar amount of copper sulfate, and continue stirring until the solution is homogeneous.

[0054] Step 2: Prepare the composite buffer solution. Dissolve sodium dihydrogen phosphate, boric acid, and polyethylene glycol sequentially in another 100 mL of nitrogen-saturated deionized water. Ensure complete dissolution and a homogeneous mixture after each addition. The concentrations of sodium dihydrogen phosphate (0.4 mol / L), boric acid (0.8 mol / L), and polyethylene glycol (1000 average molecular weight) (10 mg / L) are as follows:

[0055] Step 3: Prepare the electrolyte. Under stirring, slowly add the buffer solution from Step 2 to the copper sulfate solution from Step 1, controlling the addition rate at 10 mL / min. Then, adjust the pH of the mixed solution to 7.5 using a 0.5 mol / L potassium hydroxide solution to form a stable electrolyte. Heat the prepared electrolyte to 65°C for later use.

[0056] Step 4: Electrodeposition to prepare a copper-carbon composite electrode. In the three-electrode system, a platinum sheet electrode is used as the auxiliary electrode, a saturated calomel electrode as the reference electrode, and a 1 cm × 2 cm carbon paper substrate as the working electrode. The electrolyte prepared in Step 3 is used as the electrolyte, and a potential of -1.0 V vs. SCE is applied to the working electrode. The deposition time is controlled at 45 min to form a uniform copper-carbon composite layer, thus obtaining the copper-carbon composite electrode.

[0057] Performance testing revealed numerous protruding particles of varying sizes distributed on the surface. These particles, approximately 35 nm in size, were formed during the electrodeposition process, resulting in a relatively uniform coating. During testing, the current density at the copper oxidation peak in the CV curve was 101.5 mA cm⁻¹. -2 The effect is better than that of Example 1.

[0058] Example 3 This embodiment provides a copper-carbon composite electrode for use in an electrochemically mediated amine-based regeneration CO2 capture system. The preparation method of this copper-carbon composite electrode is as follows: Step 1: Prepare the copper complex solution. Dissolve copper sulfate in 100 mL of nitrogen-saturated deionized water and stir thoroughly to prepare a 0.06 mol / L copper sulfate solution. Then add potassium citrate as a complexing agent at twice the molar amount of copper sulfate, and continue stirring until the solution is homogeneous.

[0059] Step 2: Prepare the composite buffer solution. Dissolve sodium dihydrogen phosphate, boric acid, and polyethylene glycol sequentially in another 100 mL of nitrogen-saturated deionized water. Ensure complete dissolution and a homogeneous mixture after each addition. The concentrations of sodium dihydrogen phosphate (0.4 mol / L), boric acid (0.8 mol / L), and polyethylene glycol (400 average molecular weight) (5 mg / L) are as follows:

[0060] Step 3: Prepare the electrolyte. Under stirring, slowly add the buffer solution from Step 2 to the copper sulfate solution from Step 1, controlling the addition rate at 10 mL / min. Then, adjust the pH of the mixed solution to 7.5 using a 0.5 mol / L potassium hydroxide solution to form a stable electrolyte. Heat the prepared electrolyte to 65°C for later use.

[0061] Step 4: Electrodeposition to prepare a copper-carbon composite electrode. In the three-electrode system, a platinum sheet electrode is used as the auxiliary electrode, a saturated calomel electrode as the reference electrode, and a 1 cm × 2 cm carbon paper substrate as the working electrode. The electrolyte prepared in Step 3 is used as the electrolyte, and a potential of -1.0 V vs. SCE is applied to the working electrode. The deposition time is controlled at 45 min to form a uniform copper-carbon composite layer, thus obtaining the copper-carbon composite electrode.

[0062] Performance testing revealed numerous protruding particles of varying sizes distributed on the surface. These particles, approximately 30 nm in size, were formed during the electrodeposition process, resulting in a relatively uniform coating. During testing, the current density at the copper oxidation peak in the CV curve was 117.9 mA cm⁻¹. -2 The effect is slightly lower than that of Example 1, but better.

[0063] Example 4 This embodiment provides a copper-carbon composite electrode for use in an electrochemically mediated amine-based regeneration CO2 capture system. The preparation method of this copper-carbon composite electrode is as follows: Step 1: Prepare the copper complex solution. Dissolve copper sulfate in 100 mL of nitrogen-saturated deionized water and stir thoroughly to prepare a 0.06 mol / L copper sulfate solution. Then add sodium citrate complexing agent at twice the molar volume of copper sulfate and continue stirring until the solution is homogeneous.

[0064] Step 2: Prepare the composite buffer solution. Dissolve sodium dihydrogen phosphate, boric acid, and polyethylene glycol sequentially in another 100 mL of nitrogen-saturated deionized water. Ensure complete dissolution and a homogeneous mixture after each addition. The concentrations of sodium dihydrogen phosphate (0.6 mol / L), boric acid (0.8 mol / L), and polyethylene glycol (400 average molecular weight) (5 mg / L) are as follows:

[0065] Step 3: Prepare the electrolyte. Under stirring, slowly add the buffer solution from Step 2 to the copper sulfate solution from Step 1, controlling the addition rate at 10 mL / min. Then, adjust the pH of the mixed solution to 7.5 using a 0.5 mol / L potassium hydroxide solution to form a stable electrolyte. Heat the prepared electrolyte to 65°C for later use.

[0066] Step 4: Electrodeposition to prepare a copper-carbon composite electrode. In the three-electrode system, a platinum sheet electrode is used as the auxiliary electrode, a saturated calomel electrode as the reference electrode, and a 1 cm × 2 cm carbon paper substrate as the working electrode. The electrolyte prepared in Step 3 is used as the electrolyte, and a potential of -1.0 V vs. SCE is applied to the working electrode. The deposition time is controlled at 45 min to form a uniform copper-carbon composite layer, thus obtaining the copper-carbon composite electrode.

[0067] Performance testing revealed numerous protruding particles of varying sizes distributed on the surface. These particles, approximately 35 nm in size, were formed during the electrodeposition process, resulting in a relatively uniform coating. During testing, the current density at the copper oxidation peak in the CV curve was 102.3 mA cm⁻¹. -2 The effect was good.

[0068] Example 5 This embodiment provides a copper-carbon composite electrode for use in an electrochemically mediated amine-based regeneration CO2 capture system. The preparation method of this copper-carbon composite electrode is as follows: Step 1: Prepare the copper complex solution. Dissolve copper sulfate in 100 mL of nitrogen-saturated deionized water and stir thoroughly to prepare a 0.06 mol / L copper sulfate solution. Then add sodium citrate complexing agent at twice the molar volume of copper sulfate and continue stirring until the solution is homogeneous.

[0069] Step 2: Prepare the composite buffer solution. Dissolve sodium dihydrogen phosphate, boric acid, and polyethylene glycol sequentially in another 100 mL of nitrogen-saturated deionized water. Ensure complete dissolution and a homogeneous mixture after each addition. The concentrations of sodium dihydrogen phosphate (0.6 mol / L), boric acid (1.2 mol / L), and polyethylene glycol (400 average molecular weight) (5 mg / L) are as follows:

[0070] Step 3: Prepare the electrolyte. Under stirring, slowly add the buffer solution from Step 2 to the copper sulfate solution from Step 1, controlling the addition rate at 10 mL / min. Then, adjust the pH of the mixed solution to 7.5 using a 0.5 mol / L potassium hydroxide solution to form a stable electrolyte. Heat the prepared electrolyte to 65°C for later use.

[0071] Step 4: Electrodeposition to prepare a copper-carbon composite electrode. In the three-electrode system, a platinum sheet electrode is used as the auxiliary electrode, a saturated calomel electrode as the reference electrode, and a 1 cm × 2 cm carbon paper substrate as the working electrode. The electrolyte prepared in Step 3 is used as the electrolyte, and a potential of -1.0 V vs. SCE is applied to the working electrode. The deposition time is controlled at 45 min to form a uniform copper-carbon composite layer, thus obtaining the copper-carbon composite electrode.

[0072] Performance testing revealed numerous raised particles of varying sizes distributed on the surface. These particles, approximately 35 nm in size, were formed during the electrodeposition process, resulting in a relatively uniform coating. During testing, the current density corresponding to the copper oxidation peak in the CV curve was 101.5 mA cm⁻¹. -2 .

[0073] Example 6 This embodiment provides a copper-carbon composite electrode for use in an electrochemically mediated amine-based regeneration CO2 capture system. The preparation method of this copper-carbon composite electrode is as follows: Step 1: Prepare the copper complex solution. Dissolve copper sulfate in 100 mL of nitrogen-saturated deionized water and stir thoroughly to prepare a 0.06 mol / L copper sulfate solution. Then add sodium citrate complexing agent at twice the molar volume of copper sulfate and continue stirring until the solution is homogeneous.

[0074] Step 2: Prepare the composite buffer solution. Dissolve sodium dihydrogen phosphate, boric acid, and polyethylene glycol sequentially in another 100 mL of nitrogen-saturated deionized water. Ensure complete dissolution and a homogeneous mixture after each addition. The concentrations of sodium dihydrogen phosphate (0.6 mol / L), boric acid (1.2 mol / L), and polyethylene glycol (400 average molecular weight) (5 mg / L) are as follows:

[0075] Step 3: Prepare the electrolyte. Under stirring, slowly add the buffer solution from Step 2 to the copper sulfate solution from Step 1, controlling the addition rate at 10 mL / min. Then, adjust the pH of the mixed solution to 7.5 using a 0.5 mol / L potassium hydroxide solution to form a stable electrolyte. Heat the prepared electrolyte to 65°C for later use.

[0076] Step 4: Electrodeposition to prepare a copper-carbon composite electrode. In the three-electrode system, a platinum sheet electrode is used as the auxiliary electrode, a saturated calomel electrode as the reference electrode, and a 1 cm × 2 cm carbon paper substrate as the working electrode. The electrolyte prepared in Step 3 is used as the electrolyte, and a potential of -0.5 V vs. SCE is applied to the working electrode. The deposition time is controlled to be 20 min to form a uniform copper-carbon composite layer, thus obtaining the copper-carbon composite electrode.

[0077] Performance testing revealed numerous raised particles of varying sizes distributed on the surface. These particles, approximately 35 nm in size, were formed during the electrodeposition process, resulting in a relatively uniform coating. During testing, the current density at the copper oxidation peak in the CV curve was 89.4 mA cm⁻¹. -2 .

[0078] Example 7 This embodiment provides a copper-carbon composite electrode for use in an electrochemically mediated amine-based regeneration CO2 capture system. The preparation method of this copper-carbon composite electrode is as follows: Step 1: Prepare the copper complex solution. Dissolve copper sulfate in 100 mL of nitrogen-saturated deionized water and stir thoroughly to prepare a 0.06 mol / L copper sulfate solution. Then add sodium citrate complexing agent at twice the molar volume of copper sulfate and continue stirring until the solution is homogeneous.

[0079] Step 2: Prepare the composite buffer solution. Dissolve sodium dihydrogen phosphate, boric acid, and polyethylene glycol sequentially in another 100 mL of nitrogen-saturated deionized water. Ensure complete dissolution and a homogeneous mixture after each addition. The concentrations of sodium dihydrogen phosphate (0.6 mol / L), boric acid (1.2 mol / L), and polyethylene glycol (400 average molecular weight) (5 mg / L) are as follows:

[0080] Step 3: Prepare the electrolyte. Under stirring, slowly add the buffer solution from Step 2 to the copper sulfate solution from Step 1, controlling the addition rate at 10 mL / min. Then, adjust the pH of the mixed solution to 7.0 using a 0.5 mol / L potassium hydroxide solution to form a stable electrolyte. Heat the prepared electrolyte to 30 °C for later use.

[0081] Step 4: Electrodeposition to prepare a copper-carbon composite electrode. In the three-electrode system, a platinum sheet electrode was used as the auxiliary electrode, a saturated calomel electrode as the reference electrode, and a 1 cm × 2 cm carbon paper substrate as the working electrode. The electrolyte prepared in Step 3 was used as the electrolyte, and a potential of -0.10 V vs. SCE was applied to the working electrode. The deposition time was controlled at 45 min to form a uniform copper-carbon composite layer, thus obtaining the final copper-carbon composite electrode.

[0082] Performance testing revealed numerous protruding particles of varying sizes distributed on the surface. These particles, approximately 50 nm in size, were formed during the electrodeposition process, resulting in a relatively uniform coating. During testing, the current density at the copper oxidation peak in the CV curve was 82.4 mA cm⁻¹. -2 The effect was lower than that of Example 1, and the effect was generally poor.

[0083] Example 8 This embodiment provides a copper-carbon composite electrode for use in an electrochemically mediated amine-based regeneration CO2 capture system. The preparation method of this copper-carbon composite electrode is as follows: Step 1: Prepare the copper complex solution. Dissolve copper sulfate in 100 mL of nitrogen-saturated deionized water and stir thoroughly to prepare a 0.06 mol / L copper sulfate solution. Then add sodium citrate complexing agent at twice the molar volume of copper sulfate and continue stirring until the solution is homogeneous.

[0084] Step 2: Prepare the composite buffer solution. Dissolve sodium dihydrogen phosphate, boric acid, and polyethylene glycol sequentially in another 100 mL of nitrogen-saturated deionized water. Ensure complete dissolution and a homogeneous mixture after each addition. The concentrations of sodium dihydrogen phosphate (0.6 mol / L), boric acid (1.2 mol / L), and polyethylene glycol (1000 average molecular weight) (10 mg / L) are as follows:

[0085] Step 3: Prepare the electrolyte. Under stirring, slowly add the buffer solution from Step 2 to the copper sulfate solution from Step 1, controlling the addition rate at 10 mL / min. Then, adjust the pH of the mixed solution to 7.0 using a 0.5 mol / L potassium hydroxide solution to form a stable electrolyte. Heat the prepared electrolyte to 30 °C for later use.

[0086] Step 4: Electrodeposition to prepare a copper-carbon composite electrode. In the three-electrode system, a platinum sheet electrode was used as the auxiliary electrode, a saturated calomel electrode as the reference electrode, and a 1 cm × 2 cm carbon paper substrate as the working electrode. The electrolyte prepared in Step 3 was used as the electrolyte, and a potential of -0.10 V vs. SCE was applied to the working electrode. The deposition time was controlled at 45 min to form a uniform copper-carbon composite layer, thus obtaining the final copper-carbon composite electrode.

[0087] Performance testing revealed numerous raised particles of varying sizes distributed on the surface. These particles, approximately 70 nm in size, were formed during the electrodeposition process, resulting in a relatively uniform coating. During testing, the current density at the copper oxidation peak in the CV curve was 75.5 mA cm⁻¹. -2 The effect was lower than that of Example 1, and the effect was generally poor.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a copper-carbon composite electrode, characterized in that, include: Electrodeposition was performed using a carbon substrate as the working electrode in an electrolyte prepared from a copper complex solution and a composite buffer solution. The composite buffer solution comprises sodium dihydrogen phosphate, boric acid, and polyethylene glycol; the average molecular weight of the polyethylene glycol is 200-2000 g / mol, and the complexing agent in the copper complex solution is citrate.

2. The method for preparing the copper-carbon composite electrode according to claim 1, characterized in that, In the composite buffer solution, the concentration of sodium dihydrogen phosphate is 0.01~2.0 mol / L; and / or, the concentration of boric acid is 0.01~5 mol / L; and / or, the concentration of polyethylene glycol is 0.1~50 mg / L; and / or, the average molecular weight of polyethylene glycol is 400~1000 g / mol; and / or, the concentration ratio of sodium dihydrogen phosphate, boric acid, and polyethylene glycol is 0.4~0.8 mol / L: 0.8~1.2 mol / L: 9.5~10 mg / L.

3. The method for preparing the copper-carbon composite electrode according to claim 1 or 2, characterized in that, The copper complex solution is prepared by mixing a copper salt solution with the complexing agent; the copper salt solution is a copper sulfate solution or a copper nitrate solution, and the complexing agent is sodium citrate or potassium citrate; the concentration of the copper sulfate solution is preferably 0.01~0.2 mol / L; the amount of citrate added is preferably 1~3 times the molar amount of the copper salt.

4. The method for preparing the copper-carbon composite electrode according to any one of claims 1-3, characterized in that, It also includes adjusting the pH of the electrolyte to 6.5-7.5 using an alkaline solution; the alkaline solution contains one or more of sodium hydroxide, potassium hydroxide, and ammonia.

5. The method for preparing the copper-carbon composite electrode according to any one of claims 1-4, characterized in that, The carbon substrate is selected from one or more of graphite paper, carbon paper, carbon cloth, and carbon foam.

6. The method for preparing the copper-carbon composite electrode according to any one of claims 1-5, characterized in that, include: 1) Preparation of copper complex solution: Mix copper sulfate solution with citrate and stir to obtain copper complex solution; 2) Preparation of composite buffer solution: Sodium dihydrogen phosphate, boric acid, polyethylene glycol and water are mixed and stirred to obtain composite buffer solution; 3) Preparation of electrolyte: Mix and stir the composite buffer solution and the copper complex solution, adjust the pH value and preheat to obtain the electrolyte; 4) Preparation of copper-carbon composite electrode: Using the electrolyte as the electrolyte and the carbon substrate as the working electrode, a negative potential is applied to the carbon electrode and electrodeposition is performed to obtain a copper-carbon composite electrode.

7. The method for preparing the copper-carbon composite electrode according to claim 6, characterized in that, In steps 1) and 2), nitrogen-saturated deionized water is used to prepare the solution; And / or, in step 3), the composite buffer solution is added to the copper complex solution at a rate of 1~10 mL / min; And / or, in step 3), the preheating temperature is 30~90 ℃.

8. The method for preparing the copper-carbon composite electrode according to claim 6 or 7, characterized in that, In step 4), the negative potential is -0.01 to -1.5 V; And / or, the electrodeposition time is 0.1 to 600 min; And / or, in the three-electrode system, a carbon substrate is used as the working electrode, a platinum sheet electrode as the auxiliary electrode, and a saturated calomel electrode as the reference electrode.

9. A copper-carbon composite electrode, characterized in that, The copper-carbon composite electrode is prepared by the preparation method according to any one of claims 1-8; Preferably, a copper-carbon composite layer is deposited on the surface of the carbon substrate, and the copper nanoparticles have a particle size of 10~50 nm.

10. The application of the copper-carbon composite electrode obtained by the preparation method according to any one of claims 1-8 or the copper-carbon composite electrode according to claim 9, characterized in that, The copper-carbon composite electrode is used as an electrode in an electrochemically mediated amine-based regeneration CO2 capture system.

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