A type rich in Cu 0 / Cu + Copper-based catalysts with interfacial active sites, their preparation methods and applications

Abstract

This invention provides a Cu-rich 0 / Cu + Copper-based catalysts with interfacial active sites, their preparation methods, and applications. The method involves: synthesizing conventional Cu₂O solid materials; subjecting the synthesized Cu₂O solid materials to thermal reduction treatment to obtain Cu-rich... 0 / Cu + A copper-based catalyst with interfacial active sites. The copper-based catalyst is rich in Cu. 0 / Cu + Interfacial active sites can significantly improve the catalytic activity of electrode materials; when used as a catalyst for electrocatalytic CO2 reduction in a flow electrochemical reaction cell testing system, it can achieve an efficiency of 500 mA / cm². 2 At industrial-grade current densities, the Faraday efficiency of electrocatalysis is >89%, where C 2+ The product has a Faraday efficiency greater than 77.4%, demonstrating excellent product selectivity and high conversion efficiency.

Description

Technical Field

[0001] This invention belongs to the fields of nanotechnology and electrochemistry, specifically relating to a Cu-rich... 0 / Cu + Copper-based catalysts with interfacial active sites, their preparation methods and applications. Background Technology

[0002] In recent years, due to technological advancements and continuous upgrades in industrial capacity, environmental problems have become increasingly prominent. Among these, the increasing carbon dioxide emissions from the large-scale extraction and utilization of fossil fuels are a major cause of a series of climate issues. Therefore, developing efficient renewable energy technologies for capturing and converting carbon dioxide, and realizing the high-value utilization of carbon dioxide, is an effective strategy for mitigating global warming. Currently, electrochemical carbon dioxide reduction reactions using convenient and simple electrical energy are the most promising methods. Through this electrocatalytic reaction, carbon dioxide can be converted into a variety of common chemical products, thus providing a pathway to zero-carbon or low-carbon chemicals / fuels.

[0003] In the electrochemical reduction of carbon dioxide, by applying a certain reduction potential, CO2 molecules undergo an electrochemical reduction reaction on the electrode surface under the action of a catalyst, thereby generating a series of high-value chemical products such as CH4, CO, HCOOH, C2H4, and C2H5OH. Cu-based materials are among the most promising catalysts currently available because they can effectively activate CO2 molecules and achieve C-C coupling during the electrochemical reduction process, generating C with higher energy density. 2+ Products. However, Cu-based catalysts themselves exhibit low catalytic activity and are accompanied by vigorous hydrogen evolution side reactions, limiting the understanding of the reaction mechanism and its further development and utilization. Recent studies have found that constructing Cu within Cu-based catalysts... 0 / Cu + Interfacial active sites can effectively promote the efficiency of C-C coupling, achieving superior C-C coupling. 2+ Product selectivity. Therefore, in order to further develop the electrochemical carbon dioxide reduction reaction towards practical applications (current density > 500 mA / cm²), 2 Further rational design and development of Cu-based catalysts to enable them to possess more abundant Cu 0 / Cu + Interfacial active sites are currently the main research challenge.

[0004] Patent CN109746022A discloses a method for preparing and using a highly dispersed copper-zinc catalyst for carbon dioxide reduction. This method yields a nitrogen-doped carbon framework-coated highly dispersed copper-zinc catalyst through liquid-phase synthesis and programmed temperature calcination. When applied to the reduction of CO2 to CO, it exhibits excellent catalytic activity. However, the entire catalyst preparation process involves a complex multi-stage synthesis, resulting in significant material loss and low yield.

[0005] Patent CN112481663A discloses a method for preparing copper nanoflowers for the efficient carbon dioxide reduction reaction to produce ethylene. This method utilizes electrochemical deposition to prepare uniformly dispersed copper nanoflower catalysts by in-situ deposition on a carbon paper electrode. When applied to the electrocatalytic carbon dioxide reduction reaction, the Faradaic efficiency for ethylene is greater than 30%. However, a drawback is that this catalyst cannot be synthesized on a large scale, and the product selectivity is not high.

[0006] Patent CN113957480A discloses a copper-based catalyst, electrode, preparation method, and application for electrochemical catalytic carbon dioxide reduction energy storage. The catalyst proposed by this method is prepared by copolymerization of copper nanoparticles and a modified polymer. The modified polymer has proton-conducting side chains, which can effectively improve the catalytic efficiency and Faradaic efficiency of the copper-based catalyst. By changing the type of polymer, different methane conversion rates can be achieved. Although the copper-based catalyst prepared by this method exhibits relatively excellent catalytic performance, it cannot convert CO2 into C, which has a higher energy density. 2+ The goal of the product.

[0007] Patent CN115449823A discloses the application of an in-situ desolvation method for perovskite oxide surface-based copper nanocatalyst in electrocatalytic carbon dioxide reduction. This method proposes a novel in-situ desolvation method for preparing a perovskite oxide with the molecular formula A. x B y O 3± -Cu z The nano-copper catalyst exhibits a 35% ethylene Faradaic efficiency and excellent stability even with low Cu content. However, this catalyst has a complex composition and synthesis method, and the current density during the electrochemical reaction is below 20 mA / cm². 2 However, this makes it difficult to meet the needs of practical applications. Summary of the Invention

[0008] The purpose of this invention is to address the problems of complex synthesis methods and inability to synthesize on a large scale in existing technologies, and to propose a Cu-rich synthesis method. 0 / Cu + Copper-based catalysts with interfacial active sites, their preparation methods and applications, wherein the Cu-rich catalysts are... 0 / Cu +Copper-based catalysts with interfacial active sites are used for electrocatalytic CO2 reduction while ensuring high current density (>500 mA / cm²). 2 Under the premise of operation, a high Faraday efficiency is obtained for the electrocatalytic CO2 reduction reaction.

[0009] This invention uses a simple thermal reduction method to prepare Cu-rich materials. 0 / Cu + Copper-based catalysts with interfacial active sites are a simple and effective preparation technique.

[0010] The objective of this invention is achieved by at least one of the following technical solutions.

[0011] A type rich in Cu 0 / Cu + A method for preparing a copper-based catalyst with interfacial active sites includes the following steps:

[0012] (1) Synthesis of conventional Cu2O solid materials;

[0013] (2) The Cu2O solid material synthesized in step (1) is subjected to thermal reduction treatment to obtain Cu-rich material. 0 / Cu + Copper-based catalysts with interfacial active sites.

[0014] Furthermore, the Cu2O initial material in step (1) is of any shape and size synthesized by liquid or solid phase synthesis.

[0015] Preferably, in step (1), the initial Cu2O material is a Cu2O cube synthesized by liquid phase synthesis.

[0016] Furthermore, in step (1), the initial Cu2O material is obtained by a common liquid-phase synthesis method: using copper chloride as the copper source and ascorbic acid as the reducing agent under alkaline conditions to obtain the initial Cu2O cubic material.

[0017] Furthermore, in step (2), the thermal reduction treatment is carried out in a tubular furnace.

[0018] Furthermore, in step (2), the calcination atmosphere used in the thermal reduction treatment is one of CO, H2 or NH3, and argon or nitrogen is used as the balancing gas.

[0019] Preferably, in step (2), the calcination atmosphere used in the thermal reduction treatment is a mixture of 5% CO and 95% Ar.

[0020] Furthermore, in step (3), the flow rate of the calcining atmosphere used in the thermal reduction treatment is in the range of 5-50 mL / min.

[0021] Preferably, in step (3), the flow rate of the calcining atmosphere used in the thermal reduction treatment is 30 mL / min.

[0022] Furthermore, in step (4), the calcination temperature of the thermal reduction treatment is 100℃-500℃, and the calcination time is 1-4h.

[0023] Preferably, in step (4), the calcination temperature of the thermal reduction treatment is 250°C and the calcination time is 2 hours.

[0024] Furthermore, in step (5), the heating rate of the thermal reduction calcination is 1-10℃ / min.

[0025] Preferably, in step (5), the heating rate of the thermal reduction calcination is 1℃ / min.

[0026] The present invention provides a preparation method that yields a Cu-rich material. 0 / Cu + Copper-based catalysts with interfacial active sites.

[0027] The present invention also provides the Cu-rich 0 / Cu + Application of copper-based catalysts with interfacial active sites, wherein the Cu-rich catalysts are... 0 / Cu + Copper-based catalysts with interfacial active sites are used for electrocatalytic CO2 reduction, -500 mA / cm². 2 At the electrolysis current, the Faraday efficiency of electrocatalysis is >89%, of which C 2+ The product has a Faraday efficiency greater than 77.4%.

[0028] Furthermore, the Cu-rich 0 / Cu + Application of copper-based catalysts with interfacial active sites in electrocatalytic CO2 reduction.

[0029] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0030] (1) The Cu-rich material provided by this invention 0 / Cu + The preparation method of copper-based catalysts with interfacial active sites is a thermal reduction treatment under a CO atmosphere, which has the advantages of simple operation and large-scale synthesis. The resulting copper-based catalyst has abundant Cu. 0 / Cu + It has interfacial active sites and good reproducibility.

[0031] (2) The Cu-rich material provided by this invention 0 / Cu +Copper-based catalysts with interfacial active sites exhibit high electrocatalytic carbon dioxide reduction performance. A gas diffusion electrode prepared by spraying an ethanol dispersion of the copper-based catalyst onto carbon paper with a microporous layer can stably achieve -500 mA / cm² in an assembled flow electrolyzer. 2 The electrocatalytic reaction exhibits a Faraday efficiency >89%, where C 2+ The product's Faraday efficiency is greater than 77.4%, indicating that the Cu-rich product provided by this invention... 0 / Cu + Copper-based catalysts with interfacial active sites exhibit high C content in electrocatalytic CO2 reduction. 2+ The product is selective and has potential for practical application.

[0032] (3) The Cu-rich material provided by this invention 0 / Cu + Copper-based catalysts with interfacial active sites possess stable structures and morphologies, operating at -500 mA / cm². 2 After electrocatalytic reaction, it can still maintain its initial morphology and structure, indicating that it has excellent stability and can achieve long-term high-current electrocatalytic CO2 reduction. Attached Figure Description

[0033] Figure 1 This is a SEM image of the initial Cu2O cubic material used in this selection.

[0034] Figure 2 The Cu-rich sample prepared in Example 1 0 / Cu + SEM image of the copper-based catalyst Cu2O(CO) with interfacial active sites.

[0035] Figure 3 The Cu-rich sample prepared in Example 1 0 / Cu + XRD pattern of Cu2O(CO) catalyst with interfacial active sites.

[0036] Figure 4 Cu-rich material prepared in Example 1 0 / Cu + SEM image of copper-based catalyst Cu2O(CO) with interfacial active sites after electrocatalytic CO2 reduction.

[0037] Figure 5 Cu-rich material prepared in Example 1 0 / Cu + Auger spectrum of Cu in XPS characterization of Cu2O(CO) with interfacial active sites after electrocatalytic CO2 reduction.

[0038] Figure 6The Faraday efficiency diagram of the Cu2O(CO) electrode prepared in Example 6 for the electrocatalytic reduction of CO2 to different products in potassium hydroxide solution. Detailed Implementation

[0039] The following examples further illustrate specific implementations of the present invention, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described below are those that can be implemented or understood by those skilled in the art by referring to existing technology. Reagents or instruments whose manufacturers are not specified are considered to be conventional products that can be purchased commercially.

[0040] Figure 1 This is a SEM image of the initial Cu2O cubic material used in this selection.

[0041] Example 1

[0042] A type rich in Cu 0 / Cu + Preparation of copper-based catalysts with interfacial active sites

[0043] (1) 60 mL of 2 M NaOH solution was added dropwise to 600 mL of 10 mL CuCl2 aqueous solution at 55 °C, and the mixture was stirred continuously for 30 min. Then, 60 mL of 0.6 M ascorbic acid aqueous solution was added dropwise to the above mixed solution, and the reaction was stirred for 5 h. Subsequently, the resulting mixed solution was allowed to stand, centrifuged and washed to obtain Cu2O cubic precipitate, and the precipitate obtained after centrifugation and washing was placed in a forced-air drying oven for drying at 60 °C for 5 h.

[0044] (2) The Cu2O cubic block obtained in step (1) is transferred to a tube furnace for heating, roasting and reduction treatment. The atmosphere is a mixture of 5% CO and 95% Ar. Before roasting, the gas is purged at a flow rate of 30 mL / min for at least 30 min.

[0045] (3) The tube furnace after purging in step (2) is roasted. The roasting temperature is set to 250℃ and the roasting time is 2h, with a heating rate of 1℃ / min.

[0046] (4) After calcining in step (3) and cooling to room temperature, the Cu-rich product obtained is... 0 / Cu + The copper-based catalyst with the interfacial active sites was labeled Cu2O(CO) and quickly transferred to an Ar-protected glove box for storage to avoid oxidation.

[0047] The SEM characterization of the initial Cu2O material prepared in Example 1 is as follows: Figure 1As shown, the initial material has a smooth, flat cubic morphology; the SEM characterization of Cu2O(CO) obtained by CO thermal reduction treatment in Example 1 is as follows. Figure 2 As shown, although the catalyst maintains its initial cubic structure, uneven grooves appear on its surface; the XRD characterization of Cu2O(CO) obtained by CO thermal reduction treatment in Example 1 is as follows. Figure 3 As shown, the CO thermal reduction treatment yielded a copper-based catalyst with metallic copper as the main phase, but also containing a small amount of Cu2O phase structure.

[0048] Example 2

[0049] A type rich in Cu 0 / Cu + Preparation of copper-based catalysts with interfacial active sites

[0050] (1) 60 mL of 2 M NaOH solution was added dropwise to 600 mL of 10 mL CuCl2 aqueous solution at 55 °C, and the mixture was stirred continuously for 30 min. Then, 60 mL of 0.6 M ascorbic acid aqueous solution was added dropwise to the above mixed solution, and the reaction was stirred for 5 h. Subsequently, the resulting mixed solution was allowed to stand, centrifuged and washed to obtain Cu2O cubic precipitate, and the precipitate obtained after centrifugation and washing was placed in a forced-air drying oven for drying at 60 °C for 5 h.

[0051] (2) The Cu2O cubic block obtained in step (1) is transferred to a tube furnace for heating, roasting and reduction treatment. The atmosphere is a mixture of 5% CO and 95% Ar. Before roasting, the gas is purged at a flow rate of 10 mL / min for at least 30 min.

[0052] (3) The tubular furnace after purging in step (2) is roasted. The roasting temperature is set to 150℃ and the roasting time is 3h, with a heating rate of 1℃ / min.

[0053] (4) After calcining in step (3) and cooling to room temperature, the Cu-rich product obtained is... 0 / Cu + The copper-based catalyst with interfacial active sites was rapidly transferred to an Ar-protected glove box for storage to prevent oxidation.

[0054] Example 3

[0055] A type rich in Cu 0 / Cu + Preparation of copper-based catalysts with interfacial active sites

[0056] (1) 60 mL of 2 M NaOH solution was added dropwise to 600 mL of 10 mL CuCl2 aqueous solution at 55 °C, and the mixture was stirred continuously for 30 min. Then, 60 mL of 0.6 M ascorbic acid aqueous solution was added dropwise to the above mixed solution, and the reaction was stirred for 5 h. Subsequently, the resulting mixed solution was allowed to stand, centrifuged and washed to obtain Cu2O cubic precipitate, and the precipitate obtained after centrifugation and washing was placed in a forced-air drying oven for drying at 60 °C for 5 h.

[0057] (2) The Cu2O cubic block obtained in step (1) is transferred to a tube furnace for heating, roasting and reduction treatment. The atmosphere is a mixture of 5% CO and 95% Ar. Before roasting, the gas is purged at a flow rate of 5 mL / min for at least 30 min.

[0058] (3) The tubular furnace after purging in step (2) is roasted. The roasting temperature is set to 350℃ and the roasting time is 1h, with a heating rate of 5℃ / min.

[0059] (4) After calcining in step (3) and cooling to room temperature, the Cu-rich product obtained is... 0 / Cu + The copper-based catalyst with interfacial active sites was rapidly transferred to an Ar-protected glove box for storage to prevent oxidation.

[0060] Example 4

[0061] A type rich in Cu 0 / Cu + Preparation of copper-based catalysts with interfacial active sites

[0062] (1) 60 mL of 2 M NaOH solution was added dropwise to 600 mL of 10 mL CuCl2 aqueous solution at 55 °C, and the mixture was stirred continuously for 30 min. Then, 60 mL of 0.6 M ascorbic acid aqueous solution was added dropwise to the above mixed solution, and the reaction was stirred for 5 h. Subsequently, the resulting mixed solution was allowed to stand, centrifuged and washed to obtain Cu2O cubic precipitate, and the precipitate obtained after centrifugation and washing was placed in a forced-air drying oven for drying at 60 °C for 5 h.

[0063] (2) The Cu2O cubic block obtained in step (1) is transferred to a tube furnace for heating, roasting and reduction treatment. The atmosphere is a mixture of 5% CO and 95% Ar. Before roasting, the gas is purged at a flow rate of 30 mL / min for at least 30 min.

[0064] (3) The tubular furnace after purging in step (2) is roasted. The roasting temperature is set to 500℃ and the roasting time is 1h, with a heating rate of 10℃ / min.

[0065] (4) After calcining in step (3) and cooling to room temperature, the Cu-rich product obtained is... 0 / Cu + The copper-based catalyst with interfacial active sites was rapidly transferred to an Ar-protected glove box for storage to prevent oxidation.

[0066] Example 5

[0067] A type rich in Cu 0 / Cu + Preparation of copper-based catalysts with interfacial active sites

[0068] (1) 60 mL of 2 M NaOH solution was added dropwise to 600 mL of 10 mL CuCl2 aqueous solution at 55 °C, and the mixture was stirred continuously for 30 min. Then, 60 mL of 0.6 M ascorbic acid aqueous solution was added dropwise to the above mixed solution, and the reaction was stirred for 5 h. Subsequently, the resulting mixed solution was allowed to stand, centrifuged and washed to obtain Cu2O cubic precipitate, and the precipitate obtained after centrifugation and washing was placed in a forced-air drying oven for drying at 60 °C for 5 h.

[0069] (2) The Cu2O cubic block obtained in step (1) is transferred to a tube furnace for heating, roasting and reduction treatment. The atmosphere is a mixture of 5% H2 and 95% Ar. Before roasting, the gas is purged at a flow rate of 30 mL / min for at least 30 min.

[0070] (3) The tubular furnace after purging in step (2) is roasted. The roasting temperature is set to 550℃ and the roasting time is 1h, with a heating rate of 5℃ / min.

[0071] (4) After calcining in step (3) and cooling to room temperature, the Cu-rich product obtained is... 0 / Cu + The copper-based catalyst with interfacial active sites was labeled Cu2O(H2) and rapidly transferred to an Ar-protected glove box for storage to prevent oxidation.

[0072] Example 6

[0073] To investigate the preparation of Cu-rich... 0 / Cu + The electrocatalytic performance of copper-based catalysts with interfacial active sites is described below, using Cu-rich catalysts prepared through examples. 0 / Cu + Electrocatalytic CO2 reduction experiments were conducted using a copper-based catalyst with interfacial active sites. Example 5 used the Cu-rich catalyst obtained in Example 1. 0 / Cu +Electrocatalytic CO2 reduction experiments were conducted on a copper-based catalyst with interfacial active sites. Before conducting the electrocatalytic CO2 reduction experiments, the Cu-rich catalyst obtained in Example 1 needed to be... 0 / Cu + Copper-based catalysts with interfacial active sites are used to prepare working electrodes and assemble flow electrolyzers.

[0074] The preparation of the working electrode and the assembly of the flow electrolyzer include:

[0075] (1) Preparation of working electrode: 10 mg of Cu-rich material prepared in Example 1 was used. 0 / Cu + A copper-based catalyst material with interfacial active sites, 950 μL of isopropanol, and 50 μL of 5 wt% Nafion solution were mixed and then ultrasonically dispersed for 30 min to obtain a dispersion. A suitable amount of the dispersion was added to an air spray gun, and the catalyst was uniformly sprayed onto carbon paper with a microporous layer using the air spray gun to obtain a working electrode. On the working electrode, the Cu-rich catalyst material prepared in Example 1 was coated... 0 / Cu + The loading of copper-based catalysts at interfacial active sites is ~1 mg / cm³. 2 ;

[0076] (2) A commercially available flow electrolytic cell system made of Peek material was used as the electrochemical CO2 reduction reaction device. The electrolyte solution was a potassium hydroxide solution with a concentration of 1 mol / L, and the working electrode was the working electrode prepared in step (1) with an effective area of ​​0.5 × 2 cm. 2 The counter electrode is a platinum sheet electrode, and the reference electrode is a mercury / mercury oxide electrode.

[0077] (3) Assemble the three-electrode flow electrolytic cell system described in step (2), using rubber pads to isolate each component, and using a commercial anion exchange membrane as the electrolyte diaphragm. Fix the entire test system in place with clamps to ensure good airtightness.

[0078] After each test, the three-electrode flow electrolytic cell system was thoroughly cleaned with distilled water and then reassembled after drying.

[0079] Example 7

[0080] The three-electrode flow-type electrolytic cell system assembled in Example 6 was used to conduct an electrochemical reduction of CO2 reaction experiment. The reaction conditions were as follows: before connecting the power supply, high-purity CO2 gas was introduced into the cathode cavity at a flow rate of 30 mL / min to purge air from the entire system. Subsequently, the power supply was connected at room temperature and pressure to test the Faraday efficiency and current density. The Faraday efficiency of each product of Cu2O(CO) at different current densities was determined using constant current electrochemical technology. The current was set to -300 mA, -400 mA, -500 mA, -600 mA, and -700 mA, and each current condition was tested for 2 hours.

[0081] Figure 4 The Cu2O(CO) prepared in Example 6 above was subjected to a -500mA / cm 2 SEM images of electrocatalytic CO2 reduction under the given conditions, from Figure 4 It can be observed that the catalyst morphology remains consistent with the initial state, indicating that it has excellent structural stability. Figure 5 The Auger spectrum of Cu in the catalyst after the reaction in Example 7 is shown in the XPS. The results indicate that despite the reaction at -500 mA / cm², the reaction still yields positive results. 2 Electrolysis under certain conditions still retains a large amount of Cu. + The species indicates that the catalyst is rich in Cu. 0 / Cu + It has interfacial active sites and can remain stable throughout the entire reaction process. Figure 6 This is a Faraday efficiency diagram showing the different products obtained from the electrochemical CO2 reduction using the catalyst described in Example 7 in a flow electrolyzer. From... Figure 6 As can be seen from the data, the prepared Cu₂O(CO) catalyst operates at -500 mA / cm². 2 Under these conditions, the ethylene Faradaic efficiency reaches as high as 55%, while the Faradaic efficiency of electrocatalytic CO2 conversion is >89%, of which C 2+ The product's Faraday efficiency is greater than 77.4%, indicating that the Cu-rich product provided by this invention... 0 / Cu + Copper-based catalysts with interfacial active sites exhibit high C content in electrocatalytic CO2 reduction. 2+ The product is selective and has potential for practical application.

[0082] The above embodiments are merely preferred embodiments of the present invention and are only used to explain the present invention, not to limit the present invention. Any changes, substitutions, modifications, etc., made by those skilled in the art without departing from the spirit and essence of the present invention should be within the protection scope of the present invention.

Claims

1. A Cu-rich 0 / Cu + The application of copper-based catalysts with interfacial active sites is characterized by, The Cu-rich 0 / Cu + Copper-based catalysts with interfacial active sites were used for electrocatalytic CO2 reduction, with a reversible hydrogen electrode as the standard, at -500 mA / cm². 2 At the electrolysis current, the Faraday efficiency of electrocatalysis is >89%, of which C 2+ The product has a Faraday efficiency greater than 77.4%; the Cu-rich product... 0 / Cu + The preparation method of copper-based catalysts with interfacial active sites includes the following steps: (1) Synthesizing conventional Cu2O solid materials; (2) The Cu2O solid material synthesized in step (1) is subjected to thermal reduction treatment to obtain Cu-rich material. 0 / Cu + A copper-based catalyst with interfacial active sites; the thermal reduction calcination atmosphere is CO; the flow rate of the thermal reduction calcination atmosphere is 5-30 mL / min; the thermal reduction calcination temperature is 250 ℃-500 ℃, and the calcination time is 1-4 h; the heating rate of the thermal reduction calcination is 1-10 ℃ / min.

2. The application according to claim 1, characterized in that, In step (1), the conventional Cu2O solid material is any type of cuprous oxide of any size and shape.

3. The application according to claim 1, characterized in that, In step (2), the thermal reduction process is carried out in a tubular furnace.

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