A copper-based catalytic electrode and a preparation method and application thereof

Abstract

The application provides a copper-based catalytic electrode and a preparation method and application thereof. The copper-based electrode comprises a porous carbon base and copper species dispersed on the porous carbon base. The content of the porous carbon base is 60-90 wt% based on the weight of the copper-based catalytic electrode, and the content of the copper species is 5-20 wt%. The preparation method of the copper-based catalytic electrode comprises the following steps: (1) obtaining carbon material by activating petroleum coke; (2) preparing a carbon electrode by taking the carbon material obtained in step (1) as a base material; and (3) introducing copper on the carbon electrode obtained in step (2) to obtain the copper-based catalytic electrode. The prepared copper-based catalytic electrode shows high ethylene selectivity and good stability when used in the electro-reduction of carbon dioxide to ethylene.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic carbon dioxide reduction, and relates to an electrode material and its preparation method, particularly to a copper-based catalytic electrode for electrocatalytic reduction of carbon dioxide to ethylene and its preparation method. Background Technology

[0002] Carbon dioxide is one of the major greenhouse gases, and its massive emissions have led to global warming and environmental problems. Achieving high-value utilization of carbon dioxide has become a pressing issue, with the electrochemical conversion of carbon dioxide into high-value multi-carbon products being a promising approach. However, achieving highly selective production of these multi-carbon products remains a challenge. Compared to other metals, copper surfaces possess moderate CO* adsorption capacity and relatively weak H* adsorption capacity, thus enabling them to catalyze the electroreduction of carbon dioxide into hydrocarbons and multi-carbon products. Due to the complexity of the reaction, achieving the desired performance using single-component materials is often challenging, while combining several materials to construct nanocomposites is expected to produce excellent catalytic properties. Carbon materials, due to their high specific surface area and excellent electrochemical stability, have proven to be suitable components for combining with metals, metal oxides, and metal hydroxides for carbon dioxide electroreduction, providing unique properties due to electronic interactions, interfacial effects, and synergistic effects. This allows for the regulation of the adsorption of carbon dioxide electroreduction reaction intermediates and their distribution on the catalyst surface, providing an effective method to promote the formation of multi-carbon products.

[0003] Patent CN 113073345 A utilizes carbon or metallic materials as supports, gold-copper heterostructures as active materials, and sodium citrate and PDDA as stabilizers to prepare a supported bimetallic copper-based catalyst via electrostatic self-assembly, exhibiting high selectivity for the electrocatalytic reduction of carbon dioxide to ethanol. Patent CN 113943951A discloses a method for preparing a composite material with high formic acid Faradaic efficiency and catalytic stability in the electrocatalytic reduction of carbon dioxide. This material uses ordinary single-layer graphene and copper phthalocyanine as raw materials, and after processing, it is successfully prepared, exhibiting better stability and current density compared to other carbon material and copper phthalocyanine composite catalytic materials. Patent CN 115595607 A discloses a composite catalyst and its application for regulating the selectivity of carbon dioxide electrocatalytic reduction products. By adding carbon black to cuprous oxide micron-sized particle catalysts to form a composite electrocatalytic electrode, the selectivity of the carbon dioxide reduction product can be controlled from methane to ethylene. However, the relatively negative reaction potential required in the electrocatalytic reduction of carbon dioxide to ethylene currently leads to a significant decrease in the activity and selectivity of the catalyst during the reaction, which has become a bottleneck for the further development of this technology. Summary of the Invention

[0004] Based on the technical problems mentioned above, the present invention provides a copper-based catalytic electrode, its preparation method and application. The prepared copper-based catalytic electrode exhibits high ethylene selectivity and good stability in the electroreduction of carbon dioxide to ethylene.

[0005] Furthermore, the technical solution of the present invention mainly includes the following aspects:

[0006] I. The first aspect of the present invention provides a copper-based catalytic electrode, the copper-based electrode comprising a porous carbon matrix and copper species, wherein, based on the weight of the copper-based catalytic electrode, the content of the porous carbon matrix is ​​60wt% to 90wt%, preferably 70wt% to 80wt%; and the content of the copper species is 5wt% to 20wt%, preferably 7.5wt% to 16wt%.

[0007] Furthermore, in the aforementioned copper-based catalytic electrode, the copper species is Cu(Cu) 0 Cu2O (Cu + ) and CuO (Cu 2+ A mixture of copper species distributed on a porous carbon matrix.

[0008] Furthermore, in the aforementioned copper-based catalytic electrode, the Cu in the surface copper species... 0 The content is 10% to 60%, preferably 20% to 45%; Cu + The content is 1% to 50%, more preferably 4.5% to 40%; Cu 2+ The content is 30% to 70%, more preferably 40% to 55%.

[0009] Furthermore, in the aforementioned copper-based catalytic electrode, the copper species are nanoparticles with a particle size of 100–400 nm.

[0010] A second aspect of the present invention provides a method for preparing a copper-based catalytic electrode, comprising the following steps:

[0011] (1) After the petroleum coke and activator are mixed evenly, they are activated and then washed and dried to obtain carbon materials;

[0012] (2) Prepare carbon electrodes using the carbon material obtained in step (1) as a substrate;

[0013] (3) Copper is introduced onto the carbon electrode obtained in step (2) to obtain a copper-based catalytic electrode.

[0014] Furthermore, as a specific embodiment, the activation process in step (1) involves mixing petroleum coke and an activator evenly, and then heating the mixture under an inert atmosphere for activation. The activation temperature is 600–1100°C, preferably 700–900°C; the activation time is 5–240 min, preferably 30–120 min. The inert atmosphere is one or more of nitrogen, helium, and argon.

[0015] Furthermore, as a specific embodiment, in a more preferred case, the activation treatment in step (1) is further included in a pre-activation treatment, the pre-activation treatment temperature is 150-350℃, preferably 200-300℃, and the pre-activation treatment time is 5-200min, preferably 30-120min.

[0016] Furthermore, as a specific implementation, the petroleum coke in step (1) is a product obtained from the thermal processing of petroleum raw materials, such as a solid product obtained from the production process of a delayed coking unit.

[0017] Furthermore, as a specific implementation, the volatile matter content of the petroleum coke in step (1) is not higher than 10 wt%, preferably not higher than 8 wt%, such as 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, etc.; the particle size of the petroleum coke is 10-500 μm, preferably 30-300 μm.

[0018] Furthermore, as a specific implementation, the activator in step (1) is an alkaline activator, which is usually a hydroxide containing an alkali metal element, a salt containing an alkali metal element, a hydroxide containing an alkaline earth metal element, or a salt containing an alkaline earth metal element; the specific activator can be selected from one or more of potassium hydroxide, sodium hydroxide, calcium hydroxide, potassium carbonate, and potassium bicarbonate, preferably potassium hydroxide.

[0019] Furthermore, as a specific implementation, the mass ratio of petroleum coke to activator in step (1) is 1:0.1 to 1:3, preferably 1:0.5 to 1:1.2.

[0020] Furthermore, as a specific embodiment, in a more preferred embodiment, a modifier is introduced during the activation process in step (1). The modifier is an organic compound containing both amino and hydroxyl groups. Specifically, the compound containing both amino and hydroxyl groups can be an amino acid containing hydroxyl groups, specifically selected from one or more of serine, threonine, and tyrosine. Introducing a modifier containing both amino and hydroxyl groups during the petroleum coke activation process can form uniform metal nucleation sites on the carbon material surface, creating favorable conditions for the subsequent successful deposition of copper nanoparticles. It can also enhance the interaction between the carbon matrix and the metal.

[0021] Furthermore, as a specific implementation, the mass ratio of the modifier to petroleum coke in step (1) is 1:1 to 0.1:1, preferably 0.5:1 to 0.2:1.

[0022] Furthermore, as a specific implementation method, the water washing described in step (1) generally requires washing with water until the pH value of the filtrate is neutral. Specifically, at least one of deionized water, distilled water, and ultrapure water can be used for washing.

[0023] Furthermore, as a specific implementation, the drying temperature in step (1) is 20-120°C, preferably 40-105°C; the drying time is 1-24h, preferably 4-12h.

[0024] Furthermore, as a specific embodiment, in a more preferred case, the carbon material obtained in step (1) is first subjected to acid washing before preparing the carbon electrode. The acid washing process is as follows: the carbon material is washed by contacting an acid solution, and then washed with water and dried to obtain the carbon material; wherein, the acid solution can be an inorganic acid solution, specifically one or more of hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid, preferably hydrochloric acid. The drying temperature is 50-100℃; the drying time is 6-12h. The purpose of acid washing is to remove impurities in the carbon material to a certain extent and increase the specific surface area of ​​the carbon material.

[0025] Furthermore, as a specific implementation, the size of the carbon material obtained in step (1) before preparing the carbon electrode is preferably controlled to be 10-20 μm. For example, it can be placed in a ball mill jar and ball-milled for 1-3 hours at a speed of 100-150 rpm.

[0026] Furthermore, as a specific implementation, the carbon electrode in step (2) can be prepared using any one or more of the existing electrode preparation methods, such as at least one of the wet coating method, dry coating method, electrostatic spraying method, etc.

[0027] Furthermore, as a specific implementation, the carbon electrode preparation process in step (2) is as follows: the carbon material, conductive agent and binder obtained in step (1) are mixed evenly to obtain a slurry mixture, the slurry mixture is evenly coated on the current collector, and after the slurry is fully dried, it is rolled to obtain a porous carbon electrode.

[0028] Furthermore, as a specific implementation method, in the preparation process of the carbon electrode, the conductive agent can be at least one of conductive carbon black, graphene, carbon nanotubes, and conductive graphite.

[0029] Furthermore, as a specific embodiment, in the carbon electrode preparation process, the binder can be selected from at least one of polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), and polyvinylidene fluoride (PVDF).

[0030] Furthermore, as a specific implementation, in the carbon electrode preparation process, the current collector can be selected from at least one of glassy carbon electrode, carbon paper, carbon cloth, copper foil, titanium sheet, and stainless steel mesh.

[0031] Furthermore, in the above-mentioned method for preparing the working electrode, the ratio of carbon material, conductive agent, and binder in the carbon electrode preparation process is 7-9:0.5-2:0.5-2.

[0032] Furthermore, as a specific implementation, in the carbon electrode preparation process, the thickness of the slurry mixture uniformly coated on the current collector is generally controlled to be 0.5 to 1.0 mm.

[0033] Furthermore, as a specific implementation method, the introduction of copper onto the carbon electrode obtained in step (2) as described in step (3) can be carried out by electrochemical deposition. The specific process is as follows: copper precursor, inorganic acid, and organic compound containing polyhydroxyl groups are added to water and mixed evenly to form an electrolyte solution. Under the protection of an inert atmosphere, copper nanoparticles are grown on the surface of the carbon electrode sheet using a three-electrode system under constant potential conditions. The proportion of copper species in different valence states in the copper nanoparticles is adjusted by controlling the deposition charge. After deposition, the copper-based catalytic electrode is obtained by washing and drying.

[0034] Furthermore, as a specific embodiment, the copper precursor is a copper salt, which can be selected from one or more of copper chloride, copper sulfate, copper nitrate, and copper acetate, wherein the concentration of copper ions in the electrolyte solution is 0.01-0.2 mol / L, preferably 0.06-0.1 mol / L.

[0035] Furthermore, as a specific embodiment, the inorganic acid is preferably one or more of hydrochloric acid, sulfuric acid, and nitric acid, wherein the concentration of the inorganic acid in the electrolyte solution is 0.1–2 mol / L, preferably 0.6–1 mol / L.

[0036] Furthermore, as a specific embodiment, the organic compound containing multiple hydroxyl groups is an organic compound containing three or more hydroxyl groups, preferably an organic compound containing four or more hydroxyl groups, and can be selected from carbohydrate compounds, more specifically, one or more of glucose, fructose, lactose, and maltose, with a molar ratio to copper ions of 0.1:1 to 5:1, preferably 0.5:1 to 3:1. The addition of hydroxyl-rich carbohydrates forms a suitable hydroxyl-covered environment on the surface of copper species, optimizing the surface structure and reactivity of the catalytic electrode, providing effective sites for *CO intermediates, thereby accelerating the carbon-carbon coupling process, and simultaneously inhibiting the hydrogen evolution reaction to a certain extent, achieving high selectivity for ethylene.

[0037] Furthermore, as a specific embodiment, the working electrode in the three-electrode system is the carbon electrode obtained in step (2), the counter electrode can be at least one of graphite electrode and platinum wire electrode, preferably a graphite electrode, and the reference electrode is at least one of silver / silver chloride electrode, saturated calomel electrode, and mercury / mercury oxide electrode, preferably a silver / silver chloride electrode.

[0038] Furthermore, as a specific embodiment, the inert atmosphere can be nitrogen and / or an inert gas, and the inert gas can be one or more of helium, neon, argon, krypton, and xenon.

[0039] Furthermore, as a specific implementation, the constant voltage is -0.1V to -2.0V (vs. RHE), preferably -0.7V to -1.4V (vs. RHE).

[0040] Furthermore, as a specific implementation method, the deposition time is 100–1800 s, preferably 300–1200 s.

[0041] Furthermore, as a specific implementation method, the deposition temperature is 20–40°C.

[0042] Furthermore, as a specific implementation method, the washing is generally performed using ethanol.

[0043] Furthermore, as a specific embodiment, the drying temperature is 40–80°C, preferably dried under vacuum conditions.

[0044] Third, the third aspect of the present invention provides the application of the copper-based catalytic electrode described in the first aspect of the present invention and / or the copper-based catalytic electrode obtained by the preparation method described in the second aspect of the present invention in the electrocatalytic reduction of carbon dioxide to ethylene.

[0045] Compared with the prior art, the copper-based catalytic electrode, its preparation method, and its applications provided by the present invention have the following beneficial effects:

[0046] 1. This invention selects copper nanoparticles with high electrochemical activity as the active material and porous carbon with high specific surface area as the matrix. The active material and the support are combined through an electrochemical process, and the synergistic effect between the two is utilized to effectively electroreduc carbon dioxide into ethylene.

[0047] 2. In the process of petroleum coke activation, this invention introduces an organic compound containing both amino and hydroxyl groups as a modifier, which forms uniform metal nanocrystal nucleation sites on the surface of a porous carbon matrix, enabling copper nanoparticles to be successfully deposited on the carbon matrix; at the same time, it further enhances the interaction between the carbon support and the metal.

[0048] 3. The method of this invention utilizes electrodeposition to load copper nanoparticles onto a porous carbon electrode. The process is easily controlled and can form a continuous, uniform, and fully covered metal layer. The uniform distribution of active sites and good interfacial contact enhance the activity of carbon dioxide electroreduction to ethylene. By adjusting the electrolyte concentration and deposition charge, the valence state distribution of copper species is precisely controlled, resulting in a moderately oxidized copper surface, which is more conducive to improving ethylene selectivity. During deposition, the introduction of hydroxyl-rich organic compounds into the electrolyte creates a suitable hydroxyl-covered environment on the copper species surface, providing effective sites for *CO intermediates, thereby accelerating the carbon-carbon coupling process and inhibiting hydrogen evolution reaction to a certain extent, achieving high ethylene selectivity.

[0049] 4. The copper-based catalytic electrode provided by this invention can achieve high ethylene selectivity, activity, and stability; its ethylene Faradaic efficiency is as high as 48.5%, and its current density can reach 10.4 mA / cm². 2 It also has good stability.

[0050] 5. In the method for preparing the copper-based catalytic electrode for the electroreduction of carbon dioxide to ethylene described in this invention, petroleum coke is used as the raw material for preparing the porous carbon matrix, which provides a new method for utilizing petroleum coke and realizes the resource utilization of petroleum coke. Attached Figure Description

[0051] Figure 1 These are the XRD diffraction patterns of the catalytic electrodes provided in Examples 1, 2 and 5 of this invention.

[0052] Figure 2These are XPS Cu 2p spectra of the catalytic electrodes provided in Examples 1, 2 and 5 of this invention.

[0053] Figure 3 This is a schematic diagram of the Faraday efficiency of the catalytic electrodes provided in Examples 1-5 and Comparative Examples 1-3 of the present invention for the electrocatalytic reduction of carbon dioxide into gaseous products, including four products: hydrogen, carbon monoxide, methane, and ethylene, with an applied potential of -1.4V (vs. RHE).

[0054] Figure 4 This is a schematic diagram of the Faraday efficiency of the catalytic electrode provided in Embodiment 1 of the present invention for the electrocatalytic reduction of carbon dioxide into gaseous products, including four products: hydrogen, carbon monoxide, methane, and ethylene, with an applied potential of -1.2 to 1.6 V (vs. RHE).

[0055] Figure 5 This is a schematic diagram of the stability of the catalytic electrode with excellent ethylene Faradaic efficiency provided in Example 1 of the present invention for electrocatalytic carbon dioxide reduction reaction. The test data includes the ethylene Faradaic efficiency and current density at a voltage of -1.4V (vs. RHE). Detailed Implementation

[0056] The embodiments of the present invention will be described in further detail below with reference to examples. These examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0057] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0058] In this document, the terms "first," "second," etc., are used to distinguish two different elements or parts, and are not used to define specific positions or relative relationships. In other words, in some embodiments, the terms "first," "second," etc., can also be used interchangeably.

[0059] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0060] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0061] In the context of this invention, all numerical values ​​of parameters (e.g., quantity or condition) should be understood to be modified by the term “about” in all cases, regardless of whether “about” actually appears before the numerical value.

[0062] In the context of this invention, "substantially" means that deviations that are acceptable or considered reasonable to those skilled in the art are permitted, such as deviations within ±5%, ±2%, ±1%, ±0.5%, or ±0.1%.

[0063] Unless otherwise specified, all percentages, parts, ratios, etc., mentioned in this instruction manual are based on weight, and pressures are gauge pressures. Room temperature mentioned in this instruction manual refers to 25°C.

[0064] In the context of this invention, any two or more embodiments or aspects of this invention can be arbitrarily combined, and the resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of this invention.

[0065] In this paper, X-ray diffraction data were obtained using a Panalytical X'Pert Pro X-ray powder diffractometer under the following conditions: Cu Kα, l = 0.15406 nm, 40 kV / 40 mA, scan range: 5–70°, step size: 0.02°. X-ray electron spectroscopy data were obtained using a Shimadzu AXIS SPURA+ instrument under the following conditions: Al Kα photoelectron source, E = 1486.6 eV. All binding energies were corrected for contaminated carbon (C 1s 284.8 eV).

[0066] Example 1

[0067] Weigh 5.41g of petroleum coke powder, 2.70g of potassium hydroxide, and 1.89g of tyrosine, mix and stir to form powder, heat to 300℃ and hold for 30min under nitrogen atmosphere, then adjust the temperature to 900℃ and hold for 90min. After cooling to room temperature, filter and wash the activated product with deionized water until the pH of the filtrate is neutral, and dry the solid product at 105℃ for 12h to obtain porous carbon.

[0068] The obtained porous carbon material was acid-washed in hydrochloric acid for 2 hours, dried at 80°C for 12 hours, and then ball-milled in a ball mill jar for 1 hour at a speed of 150 rpm. Subsequently, porous carbon, conductive carbon black, and PTFE were mixed at a mass ratio of 8:1:1 and stirred for 30 minutes to obtain a slurry mixture. This slurry mixture was then uniformly coated onto a titanium sheet to a thickness of 0.80 mm. After the slurry was fully dried, it was rolled on a two-roll mill to obtain porous carbon electrode sheets, which were then cut into rectangles of 1 cm × 1.5 cm.

[0069] 0.81 g of copper chloride and 1.89 g of glucose were weighed and added to 60 mL of deionized water. Then, 0.06 mol of hydrochloric acid was added dropwise, and the mixture was stirred for 30 min to form a homogeneous electrolyte solution. Nitrogen gas was bubbled into the electrolyte at 25 °C. A porous carbon electrode was used as the working electrode, a graphite electrode as the counter electrode, and silver / silver chloride (Ag / AgCl) as the reference electrode. Deposition was performed at -1.0 V (vs. RHE) for 900 s. After deposition, the electrode was rinsed with ethanol and dried in a vacuum drying oven at 80 °C to obtain a copper-based electrode. In this copper-based electrode, the carbon support content was 74.97 wt%, and the copper species content was 14.51 wt%, wherein the copper species was a mixture of Cu, Cu₂O, and CuO, wherein Cu… 0 The content is 19.1%, Cu + The content is 35.6%, Cu 2+ The content was 45.3%.

[0070] Example 2

[0071] Weigh 5.41g of petroleum coke powder, 2.70g of potassium hydroxide, and 1.89g of tyrosine, mix and stir to form powder, heat to 900℃ and hold for 120min under nitrogen atmosphere, cool to room temperature, filter and wash the activated product with deionized water until the pH of the filtrate is neutral, and dry the solid product at 105℃ for 12h to obtain porous carbon.

[0072] The porous carbon material was acid-washed in hydrochloric acid for 2 hours, dried at 80°C for 12 hours, and then ball-milled in a ball mill jar for 1 hour at a speed of 150 rpm. Subsequently, the porous carbon, conductive carbon black, and PTFE were mixed at a mass ratio of 8:1:1 and stirred for 30 minutes to obtain a slurry mixture. This slurry mixture was then uniformly coated onto a titanium sheet to a thickness of 0.80 mm. After the slurry was fully dried, it was rolled on a two-roll mill to obtain a porous carbon electrode sheet, which was then cut into rectangles of 1 cm × 1.5 cm.

[0073] 0.81 g of copper chloride and 1.89 g of glucose were weighed and added to 60 mL of deionized water. Then, 0.06 mol of hydrochloric acid was added dropwise, and the mixture was stirred for 30 min to form a homogeneous electrolyte solution. Nitrogen gas was bubbled into the electrolyte at 25 °C. A porous carbon electrode was used as the working electrode, a graphite electrode as the counter electrode, and silver / silver chloride (Ag / AgCl) as the reference electrode. Deposition was performed at -1.0 V (vs. RHE) for 900 s. After deposition, the electrode was rinsed with ethanol and dried in a vacuum drying oven at 80 °C to obtain a copper-based electrode. In this copper-based electrode, the carbon support content was 78.79 wt%, and the copper species content was 9.81 wt%, wherein the copper species was a mixture of Cu, Cu₂O, and CuO, wherein Cu… 0 The content is 32.0%, Cu + The content is 15.2%, Cu 2+ The content was 52.8%.

[0074] Example 3

[0075] Weigh 4.17g of petroleum coke powder, 5.01g of potassium hydroxide, and 0.83g of serine, mix and stir to form powder, heat to 200℃ and hold for 60min under nitrogen atmosphere, then adjust the temperature to 800℃ and hold for 120min. After cooling to room temperature, filter and wash the activated product with deionized water until the pH of the filtrate is neutral, and dry the solid product at 80℃ for 8h to obtain porous carbon.

[0076] Porous carbon material was acid-washed in sulfuric acid for 2 hours, dried at 100°C for 8 hours, and then ball-milled in a ball mill jar for 3 hours at a speed of 100 rpm. Subsequently, porous carbon, carbon nanotubes, and PVDF were mixed at a mass ratio of 8:1:1 and stirred for 30 minutes to obtain a slurry mixture. This slurry mixture was then uniformly coated onto a glassy carbon electrode to a thickness of 0.90 mm. After the slurry was fully dried, it was rolled on a two-roll mill to obtain a porous carbon electrode sheet, which was then cut into rectangles of 1 cm × 1.5 cm.

[0077] Weigh 0.75 g of copper sulfate pentahydrate and 0.27 g of fructose and add them to 60 mL of deionized water. Then, add 0.03 mol of sulfuric acid dropwise to the solution and stir for 60 min to form a homogeneous electrolyte solution. At 30 °C, argon gas is introduced into the electrolyte. Using a porous carbon electrode sheet as the working electrode, a graphite electrode as the counter electrode, and silver / silver chloride (Ag / AgCl) as the reference electrode, deposition is performed at -0.7 V (vs. RHE) for 1200 s. After deposition, the electrode is rinsed with ethanol and dried in a vacuum drying oven at 60 °C to obtain a copper-based electrode. In this copper-based electrode, the carbon support content is 71.50 wt%, and the copper species content is 16.12 wt%, wherein the copper species is a mixture of Cu, Cu₂O, and CuO, wherein Cu… 0The content is 28.9%, Cu + The content is 29.5%, Cu 2+ The content was 41.6%.

[0078] Example 4

[0079] Weigh 4.35g of petroleum coke powder, 3.48g of potassium hydroxide, and 2.17g of threonine, mix and grind them into powder. Under a nitrogen atmosphere, heat to 300℃ and hold for 30min. Then adjust the temperature to 900℃ and hold for 120min. After cooling to room temperature, filter and wash the activated product with deionized water until the pH of the filtrate is neutral. Dry the solid product at 100℃ to obtain porous carbon.

[0080] Porous carbon materials were immersed in hydrochloric acid and deionized water for 2 hours, then sonicated for 30 minutes. After drying, they were ball-milled in a ball mill jar for 2 hours at a speed of 120 rpm. Subsequently, porous carbon, graphene, and PVA were mixed in a mass ratio of 7:1.5:1.5 and stirred for 30 minutes to obtain a slurry mixture. The slurry mixture was then uniformly coated onto a titanium sheet to a thickness of 0.70 mm. After the slurry was fully dried, it was rolled on a two-roll mill to obtain porous carbon electrode sheets, which were then cut into rectangles of 1 cm × 1.5 cm.

[0081] 0.91 g of copper nitrate trihydrate and 2.03 g of fructose were weighed and added to 60 mL of deionized water. Then, 0.04 mol of nitric acid was added dropwise to the solution, and the mixture was stirred for 60 min to form a homogeneous electrolyte solution. Helium gas was bubbled into the electrolyte at 40 °C. A porous carbon electrode was used as the working electrode, a graphite electrode as the counter electrode, and silver / silver chloride (Ag / AgCl) as the reference electrode. Deposition was performed at -1.4 V (vs. RHE) for 300 s. After deposition, the electrode was rinsed with ethanol and dried in a vacuum drying oven at 70 °C to obtain a copper-based electrode. In this copper-based electrode, the carbon support content was 79.37 wt%, and the copper species content was 11.84 wt%, wherein the copper species was a mixture of Cu, Cu₂O, and CuO, wherein Cu… 0 The content is 24.4%, Cu + The content is 27.5%, Cu 2+ The content was 48.1%.

[0082] Example 5

[0083] Weigh 5.41g of petroleum coke powder and 2.70g of potassium hydroxide, mix and grind them into powder. Under a nitrogen atmosphere, heat to 900℃ and hold for 120min. After cooling to room temperature, filter and wash the activated product with deionized water until the pH of the filtrate is neutral. Dry the solid product at 105℃ for 12h to obtain porous carbon.

[0084] The porous carbon material was acid-washed in hydrochloric acid for 2 hours, dried at 80°C for 12 hours, and then ball-milled in a ball mill jar for 1 hour at a speed of 150 rpm. Subsequently, the porous carbon, conductive carbon black, and PTFE were mixed at a mass ratio of 8:1:1 and stirred for 30 minutes to obtain a slurry mixture. This slurry mixture was then uniformly coated onto a titanium sheet to a thickness of 0.80 mm. After the slurry was fully dried, it was rolled on a two-roll mill to obtain a porous carbon electrode sheet, which was then cut into rectangles of 1 cm × 1.5 cm.

[0085] 0.81 g of copper chloride and 1.89 g of glucose were weighed and added to 60 mL of deionized water. Then, 0.06 mol of hydrochloric acid was added dropwise, and the mixture was stirred for 30 min to form a homogeneous electrolyte solution. Nitrogen gas was bubbled into the electrolyte at 25 °C. A porous carbon electrode was used as the working electrode, a graphite electrode as the counter electrode, and silver / silver chloride (Ag / AgCl) as the reference electrode. Deposition was performed at -1.0 V (vs. RHE) for 900 s. After deposition, the electrode was rinsed with ethanol and dried in a vacuum drying oven at 80 °C to obtain a copper-based electrode. In this copper-based electrode, the carbon support content was 75.97 wt%, and the copper species content was 7.59 wt%, wherein the copper species was a mixture of Cu, Cu₂O, and CuO, wherein Cu… 0 The content is 41.0%, Cu + The content is 4.7%, Cu 2+ The content was 54.3%.

[0086] Comparative Example 1

[0087] Weigh 4.17g of petroleum coke powder, 5.01g of potassium hydroxide, and 0.83g of serine, mix and stir to form powder, heat to 200℃ and hold for 60min under nitrogen atmosphere, then adjust the temperature to 800℃ and hold for 120min. After cooling to room temperature, filter and wash the activated product with deionized water until the pH of the filtrate is neutral, and dry the solid product at 80℃ for 8h to obtain porous carbon.

[0088] Porous carbon material was acid-washed in sulfuric acid for 2 hours, dried at 100°C for 8 hours, and then ball-milled in a ball mill jar for 3 hours at a speed of 100 rpm. Subsequently, porous carbon, carbon nanotubes, and PVDF were mixed at a mass ratio of 8:1:1 and stirred for 30 minutes to obtain a slurry mixture. This slurry mixture was then uniformly coated onto a glassy carbon electrode to a thickness of 0.90 mm. After the slurry was fully dried, it was rolled on a two-roll mill to obtain a porous carbon electrode sheet, which was then cut into rectangles of 1 cm × 1.5 cm.

[0089] 0.75 g of copper sulfate pentahydrate was weighed and added to 60 mL of deionized water. Then, 0.03 mol of sulfuric acid was added dropwise to the solution, and the mixture was stirred for 60 min to form a homogeneous electrolyte solution. Argon gas was introduced into the electrolyte at 30 °C. A porous carbon electrode was used as the working electrode, a graphite electrode as the counter electrode, and silver / silver chloride (Ag / AgCl) as the reference electrode. Deposition was performed at -0.7 V (vs. RHE) for 1200 s. After deposition, the electrode was rinsed with ethanol and dried in a vacuum drying oven at 60 °C to obtain a copper-based electrode. In this copper-based electrode, the carbon support content was 72.39 wt%, and the copper species content was 12.78 wt%, wherein the copper species was a mixture of Cu, Cu₂O, and CuO, wherein Cu… 0 The content is 15.5%, Cu + The content is 24.1%, Cu 2+ The content was 60.4%.

[0090] Comparative Example 2

[0091] Weigh 4.35g of petroleum coke powder, 3.48g of potassium hydroxide, and 2.17g of glycine, mix and stir to form powder. Under a nitrogen atmosphere, heat to 300℃ and hold for 30min. Then adjust the temperature to 900℃ and hold for 120min. After cooling to room temperature, filter and wash the activated product with deionized water until the pH of the filtrate is neutral. Dry the solid product at 100℃ to obtain porous carbon.

[0092] Porous carbon materials were immersed in hydrochloric acid and deionized water for 2 hours, then sonicated for 30 minutes. After drying, they were ball-milled in a ball mill jar for 2 hours at a speed of 120 rpm. Subsequently, porous carbon, graphene, and PVA were mixed in a mass ratio of 7:1.5:1.5 and stirred for 30 minutes to obtain a slurry mixture. The slurry mixture was then uniformly coated onto a titanium sheet to a thickness of 0.70 mm. After the slurry was fully dried, it was rolled on a two-roll mill to obtain porous carbon electrode sheets, which were then cut into rectangles of 1 cm × 1.5 cm.

[0093] 0.91 g of copper nitrate trihydrate and 2.03 g of fructose were weighed and added to 60 mL of deionized water. Then, 0.04 mol of nitric acid was added dropwise to the solution, and the mixture was stirred for 60 min to form a homogeneous electrolyte solution. Helium gas was bubbled into the electrolyte at 40 °C. A porous carbon electrode was used as the working electrode, a graphite electrode as the counter electrode, and silver / silver chloride (Ag / AgCl) as the reference electrode. Deposition was performed at -1.4 V (vs. RHE) for 300 s. After deposition, the electrode was rinsed with ethanol and dried in a vacuum drying oven at 70 °C to obtain a copper-based electrode. In this copper-based electrode, the carbon support content was 85.96 wt%, and the copper species content was 5.75 wt%, wherein the copper species was a mixture of Cu, Cu₂O, and CuO, wherein Cu… 0 The content is 21.2%, Cu+ The content is 20.8%, Cu 2+ The content was 58.0%.

[0094] Comparative Example 3

[0095] Weigh 6.67g of petroleum coke powder and 3.33g of potassium hydroxide, mix and stir to grind into powder, heat to 900℃ for 120min under nitrogen atmosphere, cool to room temperature, filter and wash the activated product with deionized water until the pH of the filtrate is neutral, and dry the solid product at 105℃ for 12h to obtain porous carbon.

[0096] The porous carbon material was acid-washed in hydrochloric acid for 2 hours, dried at 80°C for 12 hours, and then ball-milled in a ball mill jar for 1 hour at a speed of 150 rpm. Subsequently, the porous carbon, conductive carbon black, and polytetrafluoroethylene emulsion were mixed at a mass ratio of 8:1:1, using anhydrous ethanol as a dispersant, and stirred for 30 minutes to obtain a slurry mixture. This slurry mixture was then uniformly coated onto a titanium sheet to a thickness of 0.80 mm. After the slurry was fully dried, it was rolled on a two-roll mill to obtain a porous carbon electrode sheet, which was then cut into rectangles of 1 cm × 1.5 cm.

[0097] 0.81 g of copper chloride and 1.89 g of citric acid were weighed and added to 60 mL of deionized water. Then, 0.06 mol of hydrochloric acid was added dropwise to the solution, and the mixture was stirred for 30 min to form a homogeneous electrolyte solution. Nitrogen gas was bubbled into the electrolyte at room temperature. A porous carbon electrode was used as the working electrode, a graphite electrode as the counter electrode, and silver / silver chloride (Ag / AgCl) as the reference electrode. Deposition was performed at -1.4 V (vs. RHE) for 300 s. After deposition, the electrode was rinsed with ethanol and dried in a vacuum drying oven at 70 °C to obtain a copper-based electrode. In this copper-based electrode, the carbon support content was 86.73 wt%, and the copper species content was 3.65 wt%, wherein the copper species was a mixture of Cu, Cu₂O, and CuO, wherein Cu… 0 The content is 36.1%, Cu + The content is 4.8%, Cu 2+ The content was 59.1%.

[0098] Electrochemical performance testing of copper-based catalytic electrodes:

[0099] A series of electrocatalytic carbon dioxide reduction tests were conducted in an H-type electrolytic cell separated by a proton exchange membrane. High-purity carbon dioxide gas was introduced at a flow rate of 20 sccm / mL at the cathode side and high-purity argon gas at a flow rate of 20 sccm / mL at the anode side. A three-electrode system was used, employing 0.5 M KHCO3 solution as the electrolyte, a silver / silver chloride electrode as the reference electrode, a platinum wire electrode as the counter electrode, and a copper-based electrode as the working electrode. Cyclic voltammetry, linear sweep voltammetry, and chronoamperometry at potentials of -1.20 to -1.6 V (vs. RHE) were performed on the catalyst using an electrochemical workstation. Gas chromatography was used for qualitative and quantitative analysis of the gaseous products. The test results are as follows: Figure 3 , 4 The data are shown in Tables 1 and 2, and in Examples 1-5 and Comparative Examples 1-3. Table 1 shows the Faraday efficiency data of the catalytic electrodes provided in Examples 1-5 and Comparative Examples 1-3 for the electrocatalytic reduction of carbon dioxide into gaseous products, including four products: hydrogen, carbon monoxide, methane, and ethylene, with an applied potential of -1.4V (vs. RHE). Figure 3 Table 2 shows the Faraday efficiency data of the catalytic electrode provided in Example 1 of this invention for the electrocatalytic reduction of carbon dioxide into gaseous products, including four products: hydrogen, carbon monoxide, methane, and ethylene, with an applied potential of -1.2 to 1.6 V (vs. RHE). Figure 4 .

[0100] Table 1

[0101]

[0102] Table 2

[0103]

[0104]

[0105] like Figure 3 As shown, at a potential of -1.4V (vs. RHE), the catalyst provided in Example 1 exhibited the best ethylene Faradaic efficiency, while the catalyst provided in Example 5, which did not add any modifier during the porous carbon preparation process, showed poor performance with an ethylene Faradaic efficiency of only 19.1%. This confirms the feasibility of modifying porous carbon by introducing a modifier in this invention, providing favorable conditions for the subsequent electrodeposition process. Furthermore, the catalyst provided in Comparative Example 1, which did not have a hydroxyl-containing compound added to the electrolyte during deposition, showed significantly different electrochemical performance compared to Example 1. This indicates that introducing hydroxyl-rich compounds into the deposition electrolyte can provide a certain degree of hydroxyl coverage on the surface of copper species, thereby providing effective sites for *CO intermediates.

[0106] Figure 4As can be seen, with the increase of the applied potential, the selectivity of hydrocarbons exhibits a process of first increasing and then decreasing, with the CO selectivity gradually decreasing. This is mainly because CO has a shorter reaction pathway and a lower overpotential. However, with the increase of current density (overpotential), the adsorbed CO will further undergo hydrogenation to form hydrocarbons. The catalyst provided in Example 1 exhibits unique product selectivity characteristics; at a potential of -1.4V (vs. RHE), its ethylene Faradaic efficiency reaches 48.5%, while the H2 selectivity is only 20.9%.

Claims

1. A copper-based catalytic electrode, the copper-based electrode comprising a porous carbon matrix and copper species dispersed on the porous carbon matrix, wherein the copper species is a mixture of Cu, Cu2O and CuO, and the content of the porous carbon matrix is ​​60wt% to 90wt% and the content of the copper species is 5wt% to 20wt% based on the weight of the copper-based catalytic electrode.

2. The copper-based catalytic electrode according to claim 1, wherein, Based on the weight of the copper-based catalytic electrode, the content of porous carbon matrix is ​​70wt% to 80wt%; the content of copper species is 7.5wt% to 16wt%.

3. The copper-based catalytic electrode according to claim 1, wherein, Cu in surface copper species 0 The content is 10%–60%, more preferably 20%–45%; Cu + The content is 1% to 50%, more preferably 4.5% to 40%; Cu 2+ The content is 30% to 70%, and more preferably 40% to 55%.

4. The copper-based catalytic electrode according to claim 1, wherein, Copper species are nanoparticles with a size of 100–400 nm.

5. A method for preparing a copper-based catalytic electrode, comprising the following steps: (1) After the petroleum coke and activator are mixed evenly, they are activated and then washed and dried to obtain carbon materials; (2) Prepare a carbon electrode using the carbon material obtained in step (1) as the substrate; (3) Introduce copper onto the carbon electrode obtained in step (2) to obtain a copper-based catalytic electrode.

6. The method for preparing the copper-based catalytic electrode according to claim 5, wherein, The activation process in step (1) involves mixing petroleum coke and activator evenly, and then heating the mixture under an inert atmosphere for activation. The activation temperature is 600–1100°C, preferably 700–900°C.

7. The method for preparing the copper-based catalytic electrode according to claim 5 or 6, wherein, Before the activation treatment in step (1), there is also a pre-activation treatment, the temperature of which is 150-350℃, preferably 200-300℃.

8. The method for preparing the copper-based catalytic electrode according to claim 5, wherein, The volatile matter content of the petroleum coke in step (1) is not higher than 10 wt%, preferably not higher than 8 wt%.

9. The method for preparing the copper-based catalytic electrode according to claim 5, wherein, The activator in step (1) is an alkaline activator, which is at least one of the following: hydroxide containing alkali metal elements, salt containing alkali metal elements, hydroxide containing alkaline earth metal elements, and salt containing alkaline earth metal elements; the mass ratio of petroleum coke to activator is 1:0.1 to 1:3, preferably 1:0.5 to 1:1.

2.

10. The method for preparing the copper-based catalytic electrode according to claim 5, wherein, In the activation process of step (1), a modifier is introduced. The modifier is an organic compound containing both amino and hydroxyl groups. The compound containing both amino and hydroxyl groups is an amino acid containing hydroxyl groups. The amino acid is selected from one or more of serine, threonine, and tyrosine.

11. The method for preparing the copper-based catalytic electrode according to claim 10, wherein, In step (1), the mass ratio of the modifier to petroleum coke is 1:1 to 0.1:1, preferably 0.5:1 to 0.2:

1.

12. The method for preparing the copper-based catalytic electrode according to claim 5, wherein, The carbon material obtained in step (1) is first acid-washed before the carbon electrode is prepared. The acid-washing process is as follows: the carbon material is washed by contacting an acid solution, and then washed with water and dried to obtain the carbon material; wherein, the acid solution is an inorganic acid solution.

13. The method for preparing the copper-based catalytic electrode according to claim 5, wherein, In step (2), the carbon electrode is prepared by at least one of the following methods: wet coating, dry coating, and electrostatic spraying.

14. The method for preparing the copper-based catalytic electrode according to claim 5 or 13, wherein, The carbon electrode preparation process in step (2) is as follows: the carbon material, conductive agent and binder obtained in step (1) are mixed evenly to obtain a slurry mixture. The slurry mixture is evenly coated on the current collector. After the slurry is fully dried, it is rolled to obtain a porous carbon electrode.

15. The method for preparing the copper-based catalytic electrode according to claim 5, wherein, The conductive agent is at least one of conductive carbon black, graphene, carbon nanotubes, and conductive graphite; the binder is at least one of polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), hydroxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), and polyvinylidene fluoride (PVDF); the current collector is at least one of glassy carbon electrode, carbon paper, carbon cloth, copper foil, titanium sheet, and stainless steel mesh.

16. The method for preparing the copper-based catalytic electrode according to claim 5, wherein, The process of introducing copper onto the carbon electrode obtained in step (2) as described in step (3) is as follows: copper precursor, inorganic acid, and organic compound containing polyhydroxyl groups are added to water and mixed evenly to form an electrolyte solution. Under the protection of an inert atmosphere, copper nanoparticles are grown on the surface of the carbon electrode sheet using a three-electrode system under constant potential conditions. After deposition, the copper-based catalytic electrode is obtained by washing and drying.

17. The method for preparing the copper-based catalytic electrode according to claim 16, wherein, The copper precursor is a copper salt, which is selected from one or more of copper chloride, copper sulfate, copper nitrate, and copper acetate. The concentration of copper ions in the electrolyte solution is 0.01–0.2 mol / L, preferably 0.06–0.1 mol / L.

18. The method for preparing the copper-based catalytic electrode according to claim 16, wherein, The inorganic acid is preferably one or more of hydrochloric acid, sulfuric acid, and nitric acid, wherein the concentration of the inorganic acid in the electrolyte solution is 0.1–2 mol / L, preferably 0.6–1 mol / L.

19. The method for preparing the copper-based catalytic electrode according to claim 16, wherein, The organic compound containing multiple hydroxyl groups is an organic compound containing three or more hydroxyl groups, preferably an organic compound containing four or more hydroxyl groups, selected from carbohydrate compounds, and more specifically, can be one or more of glucose, fructose, lactose, and maltose, with a molar ratio of 0.1:1 to 5:1 with copper ions, preferably 0.5:1 to 3:

1.

20. The method for preparing the copper-based catalytic electrode according to claim 16, wherein, In the three-electrode system, the working electrode is the carbon electrode obtained in step (2), the counter electrode is at least one of graphite electrode and platinum wire electrode, preferably graphite electrode, and the reference electrode is at least one of silver / silver chloride electrode, saturated calomel electrode and mercury / mercury oxide electrode, preferably silver / silver chloride electrode.

21. The method for preparing the copper-based catalytic electrode according to claim 5, wherein, The constant voltage is -0.1 V to -2.0 V (vs. RHE), preferably -0.7 V to -1.4 V (vs. RHE); the deposition time is 100 to 1800 s, preferably 300 to 1200 s; and the deposition temperature is 20 to 40 °C.

22. A copper-based catalytic electrode obtained by the preparation method according to any one of claims 5-21.

23. The application of the copper-based catalytic electrode according to any one of claims 5-21 and / or the copper-based catalytic electrode obtained by the preparation method according to any one of claims 5-21 in the electrocatalytic reduction of carbon dioxide to ethylene.

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