Preparation method and application of high-selectivity copper-based catalyst for electrocatalytic carbon dioxide reduction reaction

Abstract

The invention belongs to the technical field of electrocatalytic reduction, and particularly relates to a preparation method and application of a high-selectivity copper-based catalyst for electrocatalytic carbon dioxide reduction reaction. The copper-based catalyst is prepared by using a multiple synergistic effect one-step method of ammonia water in the mechanical ball milling process, the method is a copper-based catalyst activation method with simple process and mild conditions, and the pore structure, the surface chemical state and the electronic property of the catalyst are synchronously optimized; therefore, the selectivity and the stability of a C2 + product prepared by reducing CO2 through electro-catalysis are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic reduction technology, and more specifically relates to a method for preparing a highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction reaction and its application. Background Technology

[0002] Carbon capture and utilization (CCU) technology has become a core breakthrough in solving the greenhouse gas dilemma. Among them, electrocatalytic carbon dioxide reduction (CO2 reduction) has shown unique advantages in the field of negative carbon conversion due to its clean electricity-driven nature and precise product control. This technology can directionally convert carbon dioxide into ethylene, ethanol, and other carbon-based products under normal temperature and pressure conditions by constructing an energy conversion chain of "CO2-green electricity-chemicals". 2+ Fuels and chemical raw materials, with the dual functions of carbon emission reduction and energy carrier synthesis.

[0003] Copper-based catalysts are currently the preferred choice for C 2+ The key material system for product synthesis has attracted much attention due to its unique d-band electronic structure, which endows it with C / C coupling capabilities. Studies show that microscopic properties such as copper crystal plane orientation, surface coordination environment, and oxidation state evolution can significantly influence the synthesis of the product. The adsorption strength and dimerization kinetics of CO intermediates provide a theoretical starting point for constructing highly selective catalytic interfaces. However, key bottlenecks still exist in practical applications: 1. High hydrogen evolution competition limits Faraday efficiency; 2. Catalyst instability caused by the reconstruction of copper active sites.

[0004] Existing solutions, such as high-temperature heat treatment and alloying, often suffer from problems such as complex processes, high energy consumption, or high costs. Therefore, it is of great significance to develop a catalyst preparation method that is simple in process, low in cost, easy to scale up, and can efficiently catalyze the reduction of carbon dioxide to produce multi-carbon products. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction reaction and its application, particularly a one-step method for preparing a copper-based catalyst using the multiple synergistic effects of ammonia water during mechanical ball milling, in order to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of this invention: provides a method for preparing a highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction reaction, comprising the following steps: Copper oxide powder was mixed with ammonia water, ball-milled, and then the solid and liquid were separated. The mixture was then washed and dried to obtain the highly selective copper-based catalyst.

[0007] Furthermore, the ammonia solution is of analytical grade.

[0008] Furthermore, the ratio of copper oxide powder to ammonia water is 1.5 g: 50-1000 μL.

[0009] Furthermore, the ball milling process is carried out at a speed of 100-1000 rpm for a duration of 0.1-12 h.

[0010] Furthermore, the drying process is vacuum drying at a temperature of 50-80℃.

[0011] This invention utilizes the immense mechanical energy provided by ball milling, combined with the chemical modification effect of ammonia, to achieve a synergistic reaction at the solid-liquid-gas multiphase interface, thereby reconstructing the microstructure and activating the surface electronic states of commercial copper oxide. Specifically, high-energy ball milling first physically breaks down and nanoscales the commercial copper oxide particles, significantly increasing their specific surface area as potential CC coupling active sites. Simultaneously, the fresh, highly reactive surface generated during the milling process can immediately interact with ammonia. On one hand, ammonia, acting as a nitrogen source, is forcibly doped into the copper oxide lattice under mechanical force, inducing local electron density rearrangement through the high electronegativity of nitrogen atoms, thus optimizing key intermediates. The adsorption energy of CO creates a suitable electronic environment for C2 coupling. On the other hand, ammonia, as an alkaline medium, produces a gentle etching and coordination effect on the particle surface during ball milling. This not only synergizes with mechanical force to construct hierarchical channels that facilitate reactant transport but also helps stabilize the advantageous crystal planes that promote C2 coupling. Ultimately, this process achieves dynamic coupling of physical activation and chemical modification, successfully converting inexpensive commercial copper oxide into a catalyst with abundant defect structures and optimized mass transfer pathways. This results in excellent selectivity and stability of C2 products in the electrocatalytic reduction of carbon dioxide.

[0012] The second technical solution of the present invention provides a highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction reaction, wherein the highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction reaction is prepared by the above preparation method.

[0013] The third technical solution of the present invention provides an application of ammonia-water synergistic mechanical ball milling in improving the catalytic activity of copper-based catalysts used for electrocatalytic carbon dioxide reduction reactions.

[0014] The fourth technical solution of the present invention provides an activation method for a copper-based catalyst for electrocatalytic carbon dioxide reduction reaction, wherein the method involves activating the copper-based catalyst by mixing it with ammonia water and then ball milling it.

[0015] Furthermore, the ammonia solution is of analytical grade.

[0016] Furthermore, the ratio of the copper-based catalyst to ammonia water is 1.5 g: 50-1000 μL.

[0017] Furthermore, the ball milling speed is 100-1000 rpm, and the time is 0.1-12 h.

[0018] Fifth technical solution of the present invention: providing an electrode for electrocatalytic carbon dioxide reduction reaction, wherein the electrode is modified with the above-mentioned highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction reaction.

[0019] The sixth technical solution of this invention: Provides a highly selective copper-based catalyst or electrode for the electrocatalytic reduction of carbon dioxide in the preparation of C... 2+ Applications in the product.

[0020] The seventh technical solution of this invention: providing an electrocatalytic reduction of carbon dioxide to prepare C 2+ A method for producing the product, wherein the above-mentioned electrode is used as the working electrode.

[0021] The present invention discloses the following technical effects: This invention provides a simple and mild method for activating copper-based catalysts. This method can simultaneously optimize the pore structure, surface chemical state, and electronic properties of the catalyst, thereby significantly improving its electrocatalytic CO2 reduction to C2. 2+ The selectivity and stability of the product.

[0022] This invention is the first to combine the chemical modification function of ammonia with the physical activation function of mechanical ball milling, achieving structural optimization and surface activation in one step. It eliminates the need for complex high-temperature calcination, template agents, or precious metal doping, significantly reducing production costs and equipment requirements. Furthermore, the process parameters are easy to control, the prepared catalyst exhibits stable performance and good reproducibility, making it suitable for large-scale industrial production.

[0023] The catalyst prepared by this invention exhibits high catalytic activity, and the obtained catalyst significantly improves C 2+ The product exhibits significantly reduced Faraday efficiency and hydrogen evolution reaction activity, with performance far exceeding that of comparative samples treated with simple physical ball milling or chemical soaking. Attached Figure Description

[0024] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a SEM image of the highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction prepared in Example 3.

[0025] Figure 2 Linear sweep voltammetry (LSV) curves of the catalyst at different ball milling speeds are shown.

[0026] Figure 3 Linear sweep voltammetry (LSV) curves of the catalyst at different ball milling times are shown.

[0027] Figure 4 Linear sweep voltammetry (LSV) curves of the catalyst under different amounts of ammonia added (Examples 1-5).

[0028] Figure 5 This is a comparison of LSV performance between Example 3 and Comparative Examples 1-3.

[0029] Figure 6 Comparison of electrocatalytic carbon dioxide reduction results in Example 3 under different current densities.

[0030] Figure 7 The Faraday efficiency is shown for different current densities in Example 3 and Comparative Examples 1-2. Detailed Implementation

[0031] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0032] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0033] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0034] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0035] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0036] Unless otherwise specified, all raw materials and reagents involved in the specific embodiments of this invention are commercially available products. Specifically, the commercial copper oxide powder was provided by Shanghai E. En Chemical Technology Co., Ltd.

[0037] Unless otherwise specified, room temperature and normal temperature in the specific embodiments of this invention refer to 20-30℃.

[0038] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0039] In some specific embodiments, the present invention provides a method for preparing a highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction reaction, the steps of which include: S1. Mix copper oxide powder with analytical grade ammonia water until homogeneous to obtain a mixture. The ratio of copper oxide powder to ammonia water is 1.5 g: 50-1000 μL. S2. Load the mixture into the ball mill jar and place the ball mill jar on the ball mill. Mill the mixture at a speed of 100-1000 rpm for 0.1-12 hours. S3. After ball milling, the product is centrifuged and washed with deionized water and ethanol to remove residual ammonia and impurities. S4. The washed solid product is dried in a vacuum oven at 50-80℃ for 12 hours to obtain a copper-based catalyst activated by ammonia-water synergistic mechanical ball milling, which is a highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction reaction.

[0040] In this invention, the chemical modification function of ammonia water is combined with the physical activation function of mechanical ball milling to achieve structural optimization and surface activation in one step. This eliminates the need for complex high-temperature calcination, template agents, or noble metal doping, thus producing a highly active catalyst. Specifically, the chemical modification of ammonia water can regulate the electronic structure of copper atoms through nitrogen doping, while the physical activation through mechanical ball milling effectively increases lattice defects and promotes uniform composite formation between components through high-intensity mechanical force. The synergistic effect of these two methods achieves structural optimization (forming a porous, defect-rich microstructure) and surface activation (simultaneously introducing abundant active sites and enhancing the adsorption and activation capabilities of reactant molecules). Example 1 The preparation steps of a highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction include: S1. Mix 1.5 g of commercial copper oxide powder with 50 μL of analytical grade ammonia water until homogeneous to obtain a mixture. S2. Load the mixture into the ball mill jar and place the ball mill jar on the ball mill. Mill at 600 rpm for 40 minutes. S3. After ball milling, the product is centrifuged and washed with deionized water and ethanol to remove residual ammonia and impurities. S4. The washed solid product is dried in a vacuum oven at 60 °C for 12 h to obtain a copper-based catalyst activated by ammonia-water synergistic mechanical ball milling, which is a highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction reaction.

[0041] Example 2 Compared with Example 1, the only difference is that the amount of ammonia water used is adjusted to 150 μL. The specific steps are as follows: S1. Mix 1.5 g of commercial copper oxide powder with 150 μL of analytical grade ammonia water until homogeneous to obtain a mixture. S2. Load the mixture into the ball mill jar and place the ball mill jar on the ball mill. Mill at 600 rpm for 40 minutes. S3. After ball milling, the product is centrifuged and washed with deionized water and ethanol to remove residual ammonia and impurities. S4. The washed solid product is dried in a vacuum oven at 60 °C for 12 h to obtain a copper-based catalyst activated by ammonia-water synergistic mechanical ball milling, which is a highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction reaction.

[0042] Example 3 Compared with Example 1, the only difference is that the amount of ammonia water used is adjusted to 250 μL. The specific steps are as follows: S1. Mix 1.5 g of commercial copper oxide powder with 250 μL of analytical grade ammonia water until homogeneous to obtain a mixture. S2. Load the mixture into the ball mill jar and place the ball mill jar on the ball mill. Mill at 6000 rpm for 40 minutes. S3. After ball milling, the product is centrifuged and washed with deionized water and ethanol to remove residual ammonia and impurities. S4. The washed solid product is dried in a vacuum oven at 60 °C for 12 h to obtain a copper-based catalyst activated by ammonia-water synergistic mechanical ball milling, which is a highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction reaction.

[0043] Example 4 Compared with Example 1, the only difference is that the amount of ammonia water used is adjusted to 350 μL. The specific steps are as follows: S1. Mix 1.5 g of commercial copper oxide powder with 350 μL of analytical grade ammonia water until homogeneous to obtain a mixture. S2. Load the mixture into the ball mill jar and place the ball mill jar on the ball mill. Grind at 600 rpm for 40 minutes. S3. After ball milling, the product is centrifuged and washed with deionized water and ethanol to remove residual ammonia and impurities. S4. The washed solid product is dried in a vacuum oven at 60 °C for 12 h to obtain a copper-based catalyst activated by ammonia-water synergistic mechanical ball milling, which is a highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction reaction.

[0044] Example 5 Compared with Example 1, the only difference is that the amount of ammonia water used is adjusted to 500 μL. The specific steps are as follows: S1. Mix 1.5 g of commercial copper oxide powder with 500 μL of analytical grade ammonia water until homogeneous to obtain a mixture. S2. Load the mixture into the ball mill jar and place the ball mill jar on the ball mill. Mill at 600 rpm for 40 minutes. S3. After ball milling, the product is centrifuged and washed with deionized water and ethanol to remove residual ammonia and impurities. S4. The washed solid product is dried in a vacuum oven at 60 °C for 12 h to obtain a copper-based catalyst activated by ammonia-water synergistic mechanical ball milling, which is a highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction reaction.

[0045] Example 6 The only difference from Example 3 is that the ball milling speed is 200 rpm, 400 rpm, or 800 rpm.

[0046] Example 7 The only difference from Example 3 is that the ball milling time is 20 min or 60 min.

[0047] Comparative Example 1 Untreated commercial copper oxide powder was used as a copper-based catalyst.

[0048] Comparative Example 2 Compared to Example 3, the only difference is that the ammonia water is replaced with an equal volume of deionized water. The specific steps are as follows: S1. Mix 1.5 g of commercial copper oxide powder with 250 μL of deionized water until homogeneous to obtain a mixture. S2. Load the mixture into the ball mill jar and place the ball mill jar on the ball mill. Mill at 600 rpm for 40 minutes. S3. After ball milling, the product is centrifuged and washed with deionized water and ethanol to remove impurities. S4. The washed solid product was dried in a vacuum oven at 60 °C for 12 h to obtain a copper-based catalyst.

[0049] Comparative Example 3 Compared with Example 3, the only difference is that the ball milling step will be reduced. The specific steps are as follows: S1. Mix 1.5 g of commercial copper oxide powder with 250 μL of analytical grade ammonia water evenly, let it stand and soak for 12 hours at room temperature. After soaking, centrifuge the product and wash it with deionized water and ethanol to remove residual ammonia and impurities. S2. The washed solid product was dried in a vacuum oven at 60 °C for 12 h to obtain a copper-based catalyst.

[0050] Test case Figure 1 This is a SEM image of the highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction prepared in Example 3. As can be seen from the image, after ball milling with ammonia, the particles are effectively refined, with a more uniform size distribution, and the surface becomes rougher, exposing more active sites. This is beneficial for the adsorption and transformation of reactants and intermediates.

[0051] The catalysts prepared in Examples 1-7 and Comparative Examples 1-3 were used as samples for comparative experiments. The specific steps are as follows: 8 mg of catalyst was dispersed in 3 mL of ethanol solution, and 40 μL of Nafion solution was added. The mixture was then sonicated to form a homogeneous slurry, which was subsequently drop-coated onto hydrophobic carbon paper to achieve a loading of 1 mg / cm³. -2 The electrode was prepared by naturally drying the material to produce a working electrode for the electrocatalytic reduction of carbon dioxide.

[0052] The prepared working electrode was subjected to linear sweep voltammetry to test its catalytic activity. Specifically: Using an iridium mesh as the counter electrode and an Hg / HgO electrode as the reference electrode, the electrolyte was 1 mol / L KOH, and the test was conducted in a flow cell under CO2 conditions (flow rate of 30 mL / min).

[0053] Figures 2-5 The results are linear sweep voltammetry tests for different working electrodes.

[0054] in, Figure 2The figure shows the linear sweep voltammetry (LSV) curves of the catalyst at different ball milling speeds. As can be seen from the figure, at higher speeds of 600 rpm and 800 rpm, the performance curves of the catalyst tend to be consistent, indicating that further increases in speed at this high level do not significantly improve performance. Therefore, from the perspective of equipment energy consumption and process economy, the present invention prefers 600 rpm as the ball milling speed. Figure 3 Linear sweep voltammetry (LSV) curves of the catalyst under different ball milling times were obtained. The results showed that the LSV curves of the obtained catalysts had a high degree of overlap in the ball milling time range of 20 min to 60 min, indicating that the change of ball milling time did not have a significant impact on the electrocatalytic performance of the catalyst within this range. Based on efficiency and cost considerations, this invention selected 20 min as the optimized ball milling time. Figure 4 Linear sweep voltammetry (LSV) curves of the catalysts with different amounts of ammonia added (Examples 1-5) were obtained. The results showed that, compared with other examples, the catalyst corresponding to Example 3 exhibited the highest cathode current density, which indicates that it has the best initial electrocatalytic activity in this series of experiments. Figure 5 The figure shows a comparison of LSV performance between Example 3 and Comparative Examples 1-3. As can be seen, compared to the untreated catalyst of Comparative Example 1, the catalyst prepared in Example 3 exhibits a significantly enhanced cathode current density and a markedly positive shift in onset potential. This result confirms that the ammonia-mechanical-chemical synergistic modification process described in this invention can effectively optimize the surface characteristics of the catalyst, thereby providing a higher density of active sites or a better reaction kinetic pathway, ultimately significantly improving its electrocatalytic carbon dioxide reduction performance.

[0055] The working electrode from Example 3 was assembled in a membrane electrode assembly, and electrocatalytic carbon dioxide reduction tests were conducted at different current densities. An iridium mesh was used as the counter electrode, and 1 mol of KOH was continuously pumped into the anode and cathode chambers using a peristaltic pump. Electrocatalytic carbon dioxide reduction tests were then performed at different current densities, and the results are as follows: Figure 6 and Figure 7 As shown.

[0056] Figure 6 The figure shows a comparison of the electrocatalytic carbon dioxide reduction results of Example 3 under different current densities. As can be seen from the figure, with increasing current density, the Faradaic efficiency (FE) of the C2 product first increases and then tends to stabilize at 500 mA / cm². -2 The Faraday efficiency of the C2 product reaches a peak of 75% at the current density, demonstrating excellent reaction kinetics and mass transfer performance.

[0057] Figure 7The figures show the Faraday efficiency of Example 3 and Comparative Examples 1-2 at different current densities. As can be seen from the figures, the C2 Faraday efficiency of copper oxide etched with mechanically assisted ammonia in Example 3 is as high as 75%, and the catalytic activity of copper oxide is significantly improved after etching with ammonia.

[0058] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0059] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction, characterized in that the steps include... include: Copper oxide powder was mixed with ammonia water, ball-milled, and then the solid and liquid were separated. The mixture was then washed and dried to obtain the highly selective copper-based catalyst.

2. The method for preparing a highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction reaction as described in claim 1, characterized in that, The ammonia solution was of analytical grade. And / or, the ratio of copper oxide powder to ammonia is 1.5 g: 50-1000 μL.

3. The method for preparing a highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction reaction as described in claim 1, characterized in that, The ball milling process is carried out at a speed of 100-1000 rpm for a duration of 0.1-12 h. And / or, the drying is vacuum drying at a temperature of 50-80°C.

4. A highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction, characterized in that, The highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction is prepared by the method for preparing a highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction according to any one of claims 1-3.

5. The application of ammonia-water co-mechanical ball milling in improving the catalytic activity of copper-based catalysts used for electrocatalytic carbon dioxide reduction reaction.

6. An electrode for electrocatalytic carbon dioxide reduction reaction, characterized in that, The electrode is modified with the highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction reaction as described in claim 4.

7. A method for activating a copper-based catalyst for electrocatalytic carbon dioxide reduction, characterized in that, The method involves activating the copper-based catalyst by co-ball milling it with ammonia.

8. The activation method as described in claim 7, characterized in that, The ammonia solution was of analytical grade. And / or, the ratio of the copper-based catalyst to ammonia is 1.5 g: 50-1000 μL; And / or, the ball milling speed is 100-1000 rpm, and the time is 0.1-12 h.

9. A highly selective copper-based catalyst for electrocatalytic carbon dioxide reduction reaction as described in claim 4, or an electrode as described in claim 6, for the electrocatalytic reduction of carbon dioxide to prepare C 2+ Applications in the product.

10. An electrocatalytic method for the reduction of carbon dioxide to prepare C 2+ The method for producing the product is characterized by, The method uses the electrode described in claim 6 as the working electrode.

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