A fluorine-doped hydrophobic porous carbon supported copper catalyst, a preparation method and application thereof

Abstract

The application discloses a fluorine-doped hydrophobic porous carbon supported copper catalyst and a preparation method and application thereof, and belongs to the technical field of catalysts. The application aims to solve the technical problems of a lack of enrichment ability of a catalyst interface to carbon dioxide molecules, poor electrical conductivity, limited pore structure, and a small number of copper active sites, and the like. A fluorine and nitrogen co-doped hydrophobic porous carbon carrier with rich pores and semi-ionic carbon-fluorine bonds is prepared by using a fluorine-containing monomer copolymerization strategy to prepare a polyimide precursor powder, and then sintering and reconstruction. Finally, a copper active component is highly dispersed on the carrier by using a post-infiltration and reduction process. By using a step-by-step strategy of 'firstly loading a carrier to form pores, and then loading a metal at a low temperature', a reaction interface with high electrical conductivity and an intrinsic hydrophobic surface is constructed, the anti-wetting ability and the material transmission efficiency of the catalyst are improved, and the high dispersion of the copper active sites is ensured. The preparation process is simple and controllable, and is suitable for large-scale preparation.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to a fluorine-doped hydrophobic porous carbon-supported copper catalyst, its preparation method, and its application. Background Technology

[0002] The chemical industry plays a vital role in economic development. Modern chemical production and development are closely linked to catalysts. For example, petrochemicals, coal chemicals, and oleochemicals, which account for a large proportion of demand, all require catalysts to complete their production processes. Currently, to address increasingly severe environmental problems and the dwindling supply of fossil fuels, the chemical industry has shifted its focus from quantity to cleanliness, efficiency, and cost-effectiveness. Developing high-performance catalysts and high-efficiency catalytic technologies is key to solving industrial production efficiency problems and addressing low energy utilization.

[0003] Among numerous metal catalysts, copper is currently known to be the most effective metal for catalyzing the deep reduction of carbon dioxide to produce multi-carbon products. However, in this reaction system, copper-based catalysts face a severe challenge from hydrogen evolution reaction (HEP). Because the reaction takes place in an aqueous electrolyte, water molecules have a very high coverage on the electrode surface, leading to the competitive HEP reaction often dominating. Furthermore, traditional copper-based catalysts lack the ability to enrich carbon dioxide molecules at the interface, thus limiting reaction efficiency.

[0004] To suppress hydrogen evolution side reactions, existing technologies often employ the physical mixing of hydrophobic agents such as polytetrafluoroethylene (PTFE) to construct hydrophobic interfaces. However, PTFE is an insulator, and physical coating severely hinders electron transport and easily clogs catalyst pores, leading to a decrease in overall reactivity. Another approach is a one-step pyrolysis method, which involves directly introducing a metal source during the polymerization stage followed by high-temperature pyrolysis. However, this method often results in severe agglomeration of metal particles at high temperatures or complete encapsulation by a thick carbon layer, preventing the exposure of active sites.

[0005] Polyimide is a high-molecular-weight polymer with imide or phthalimide rings in its molecular chain. It possesses excellent mechanical and electrical properties, as well as good chemical and radiation resistance, and is widely used in aerospace, military chemical, electronic devices, and filters. The introduction of fluorine atoms can not only adjust the hydrophobicity of the material but also alter the electronic structure of the carbon skeleton. However, combining the structural advantages of fluorocarbon materials with highly dispersed loading technology of copper active components to prepare copper-based catalysts with high conductivity, abundant pore structure, and excellent hydrophobic surface remains a pressing problem in the field.

[0006] Relevant patent documents retrieved:

[0007] The document, published in China (CN120885228A) on November 4, 2025, discloses a green and efficient method for preparing a copper catalyst. The method includes the following steps: (1) mixing basic copper carbonate, ammonia, and water, and simultaneously adding ammonium salt to prepare a copper-ammonia solution as a precursor solution at room temperature; (2) mixing the precursor solution with a support or a support precursor to achieve active component loading and catalyst preparation; and (3) filtering, washing, drying, and calcining the mixture from step (2) to obtain a copper-based catalyst. The copper-ammonia complex precursor solution prepared by this invention can achieve preparation of a copper-ammonia complex solution at room temperature, avoiding the heating operation during precursor preparation. Furthermore, using a basic copper carbonate precursor to prepare the copper-based catalyst can reduce the nitrogen content of the system and nitrogen emissions during the subsequent calcination process, achieving efficient and green catalyst preparation.

[0008] The document, published in China (CN115945079A) on April 11, 2023, discloses a method for preparing and applying a fluorinated crosslinkable polyimide-based carbon molecular sieve membrane. The method uses 4,4'-(hexafluoroisopropene) phthalic anhydride as the dianhydride monomer and 3,5'-diaminobenzoic acid and 4,4'-diaminodiphenyl ether as common diamine monomers to copolymerize a polyamic acid solution.

[0009] The prior art represented by the aforementioned documents has at least the following unresolved technical problems or defects:

[0010] 1. Existing technologies have not been able to simultaneously solve the two major problems of severe hydrogen evolution caused by interfacial hydrophilicity and metal deactivation caused by high-temperature pyrolysis.

[0011] 2. Existing technologies have not been able to solve the problem that when a metal source is introduced during the polymerization stage and then pyrolyzed at high temperatures, the metal particles will severely agglomerate or be completely covered by a thick carbon layer, preventing the active sites from being exposed. Summary of the Invention

[0012] The purpose of this invention is to provide:

[0013] A fluorine-doped hydrophobic porous carbon-supported copper catalyst, its preparation method, application, and related technologies are disclosed to address technical problems such as the lack of carbon dioxide molecule enrichment capacity at the catalyst interface, resulting in limited reaction efficiency; poor conductivity; limited pore structure; and few copper active sites, or combinations thereof.

[0014] Terminology Explanation:

[0015] Unless otherwise defined, all technical terms in this document have the same meanings as commonly understood by one of ordinary skill in the art to which the subject matter of the claims pertains. Unless otherwise stated, all patents, patent inventions, and publications cited in this document are incorporated herein by reference in their entirety. If multiple definitions exist for terms in this document, the definitions in this chapter shall prevail.

[0016] It should be understood that the above brief description and the following detailed description are exemplary and for illustrative purposes only, and do not limit the subject matter of the invention in any way. In this invention, the singular is used in conjunction with the plural unless otherwise specifically stated. It should also be noted that, unless otherwise stated, the use of “or” or “or” means “and / or”. Furthermore, the use of the term “comprising” and other forms such as “including,” “containing,” and “contains” are not limiting.

[0017] Unless specifically defined herein, the use of all commercially available products herein employs standard techniques. For example, it may be carried out using the manufacturer's instructions for use with the kit, or in accordance with methods known in the art or the description of this invention. The techniques and methods described herein can generally be implemented according to conventional methods well known in the art, based on the descriptions in the various summary and more specific documents cited and discussed in this specification.

[0018] The terms “optional / arbitrary” or “optionally / arbitrarily” mean that the event or situation described below may or may not occur, including both the occurrence and non-occurrence of the event or situation.

[0019] The term "hydrogen evolution reaction" as used in this article refers to an electrode or surface reaction that occurs at the cathode or reducing active site during electrolysis, photocatalysis, or photoelectrochemical processes, resulting in the reduction of protons or water molecules to hydrogen. This reaction typically involves multiple proton-electron coupling and transfer processes and is a key half-reaction in fields such as water splitting for hydrogen production and electrochemical energy conversion.

[0020] The term "mixing" as used in this article refers to the process of combining two or more different substances (which may be solid, liquid, gas, or a combination of different states) through physical or mechanical means to form a macroscopically homogeneous or relatively homogeneous dispersion system.

[0021] The term "stirring" as used in this article refers to the operation of mixing multiple substances evenly by means of machinery or manual agitation. Specifically, it refers to the process of creating flow in a container with the help of external forces (such as rotating blades, stirring rods, airflow, etc.) to achieve uniform mixing of solids, liquids, or gases.

[0022] In a first aspect, the present invention provides: a method for preparing a fluorine-doped hydrophobic porous carbon-supported copper catalyst, comprising: preparing a polyimide precursor powder using a mixture of amine monomers and acid anhydride monomers as raw materials; subsequently, sintering and reconstructing the polyimide precursor powder to obtain a fluorine-nitrogen co-doped hydrophobic porous carbon support; and finally loading copper active components onto the hydrophobic porous carbon support.

[0023] The molar ratio of the mixture of amine monomers and acid anhydride monomers is 1:1.4-1.6;

[0024] The anhydride monomer mixture is a mixture of pyromellitic dianhydride and 4,4'-(hexafluoroisopropylidene) phthalic anhydride in a molar ratio of 7-8:2-3.

[0025] The sintering temperature is 700-900℃.

[0026] Preferably, the molar ratio of the mixture of amine monomers and acid anhydride monomers is selected from any value or range between 1:1.4 and 1.6, specifically from: 1:1.4, 1:1.45, 1:1.5, 1:1.55, 1:1.6 or any two of them.

[0027] More preferably, the molar ratio of the mixture of amine monomers and acid anhydride monomers is selected from any value or range between 1:1.4 and 1.5, specifically from 1:1.4, 1:1.45, 1:1.5 or any two of them.

[0028] More preferably, the molar ratio of the mixture of amine monomers and acid anhydride monomers is 1:1.5.

[0029] Preferably, the anhydride monomer mixture is any value or range of a mixture of pyromellitic dianhydride and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride with a molar ratio selected from 7-8:2-3, specifically selected from: 7:2, 7:3, 8:2, 8:3 or any range between two of them.

[0030] More preferably, the anhydride monomer mixture is a mixture of pyromellitic dianhydride and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride in a molar ratio of 7:3.

[0031] Preferably, the sintering temperature is selected from any value or range between 700-900℃, specifically from: 700℃, 750℃, 800℃, 850℃, 900℃ or any two of them.

[0032] More preferably, the sintering temperature is selected from any value or range between 800-900℃.

[0033] More preferably, the sintering temperature is 900°C.

[0034] Preferably, the preparation of the polyimide precursor powder includes the following steps:

[0035] The mixture of amine monomers and acid anhydride monomers is dissolved in a solvent, stirred, and after the reaction is complete, centrifuged, washed, and dried to obtain the final product.

[0036] Preferably, the amine monomer is selected from one or more of 1,3,5-tris(4-aminophenyl)benzene and 4,4'-diaminodiphenyl ether.

[0037] More preferably, the amine monomer is 1,3,5-tris(4-aminophenyl)benzene.

[0038] Preferably, the solvent is selected from one or more of acetone, ethanol, butanone, and ethyl acetate.

[0039] More preferably, the solvent is a mixture of acetone and ethanol.

[0040] Preferably, the volume ratio of acetone to ethanol is selected from any value or range between 5 and 10:1, specifically from: 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, 9.5:1, 10:1 or any two of them.

[0041] More preferably, the volume ratio of acetone to ethanol is selected from any value or range between 8 and 10:1.

[0042] More preferably, the volume ratio of acetone to ethanol is 10:1.

[0043] Preferably, the temperature of the stirring reaction is selected from any value or range between -10 and 10°C, specifically from: -10°C, -9°C, -8°C, -7°C, -6°C, -5°C, -4°C, -3°C, -2°C, -1°C, 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C, 9°C, 10°C or any two of them.

[0044] More preferably, the temperature of the stirring reaction is selected from any value or range between -10 and 0°C, specifically from: -10°C, -9°C, -8°C, -7°C, -6°C, -5°C, -4°C, -3°C, -2°C, -1°C, 0°C or any two of them.

[0045] More preferably, the temperature of the stirring reaction is 0°C.

[0046] Preferably, the centrifugal speed is selected from any value or range between 500-1000 r / min, specifically from: 500 r / min, 550 r / min, 600 r / min, 650 r / min, 700 r / min, 750 r / min, 800 r / min, 850 r / min, 900 r / min, 950 r / min, 1000 r / min or any range between two of them.

[0047] More preferably, the centrifugal speed is selected from any value or range between 800-1000 r / min.

[0048] More preferably, the centrifugal speed is selected from any value or range between 900-1000 r / min.

[0049] More preferably, the centrifugation speed is 1000 r / min.

[0050] Preferably, the centrifugation time is selected from any value or range between 10 and 30 minutes, specifically from 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, or any two of these ranges.

[0051] More preferably, the centrifugation time is selected from any value or range between 10 and 20 minutes.

[0052] More preferably, the centrifugation time is 10 minutes.

[0053] Preferably, the drying temperature is selected from any value or range between 30-60℃, specifically from: 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃ or any two of them.

[0054] More preferably, the drying temperature is selected from any value or range between 40-60°C.

[0055] More preferably, the drying temperature is 60°C.

[0056] Preferably, the drying time is selected from any value or range between 10 and 15 hours, specifically from 10 hours, 12 hours, 13 hours, 14 hours, 15 hours or any two of these ranges.

[0057] More preferably, the drying time is selected from any value or range between 10 and 13 hours.

[0058] More preferably, the drying time is selected from any value or range between 12 and 13 hours.

[0059] More preferably, the drying time is 12 hours.

[0060] Preferably, the sintering reconstruction includes the following steps:

[0061] The polyimide precursor powder was sintered in an inert atmosphere, kept at a constant temperature, and then cooled.

[0062] Preferably, the sintering temperature is increased at a rate of 2-10°C / min.

[0063] Preferably, the sintering time is selected from any value or range between 2 and 5 hours, specifically from: 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours or any two of them.

[0064] More preferably, the sintering time is selected from any value or range between 3 and 5 hours.

[0065] More preferably, the sintering time is 5 hours.

[0066] Preferably, the cooling temperature is selected from any value or range between 20-30℃, specifically from: 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃, 30℃ or any two of them.

[0067] More preferably, the cooling temperature is selected from any value or range between 23-30°C.

[0068] More preferably, the cooling temperature is selected from any value or range between 23-25°C.

[0069] More preferably, the cooling temperature is 25°C.

[0070] Preferably, the step of loading the copper active component onto the hydrophobic porous carbon support includes the following steps:

[0071] The hydrophobic porous carbon support is dispersed in solvent A, a copper source is added, and after stirring, solvent A is removed to obtain powder A, which is then reduced to obtain the final product.

[0072] Preferably, solvent A is selected from one or more of ethanol, methanol, acetone, tetrahydrofuran, and deionized water.

[0073] More preferably, solvent A is isopropanol.

[0074] Preferably, the mass-to-volume ratio of the hydrophobic porous carbon support and the solvent is selected from any value or range between 0.1-0.5g:20-100mL, specifically from: 0.1g:20mL, 0.1g:30mL, 0.1g:40mL, 0.1g:45mL, 0.1g:50mL, 0.1g:55mL, 0.1g:60mL, 0.1g:80mL, 0.1g:100mL, 0.2g:20mL, 0.2g:30mL, 0. 2g:40mL, 0.2g:45mL, 0.2g:80mL, 0.2g:100mL, 0.3g:40mL, 0.3g:45mL, 0.3g:50mL, 0.3g:55mL, 0.3g:60mL, 0.4g:20mL, 0.4g:30mL, 0.4g:50mL, 0.5g:55mL, 0.5g:60mL, 0.5g:80mL, 0.5g:100mL, or any range between two of these.

[0075] More preferably, the mass-to-volume ratio of the hydrophobic porous carbon support to the solvent is selected from any value or range between 0.1-0.3g:20-50mL.

[0076] More preferably, the mass-to-volume ratio of the hydrophobic porous carbon support and the solvent is selected from any value or range between 0.1g:20-30mL.

[0077] More preferably, the mass-to-volume ratio of the hydrophobic porous carbon support to the solvent is 0.1 g: 20 mL.

[0078] Preferably, the reduction method is a liquid-phase chemical reduction method or a low-temperature thermal reduction method.

[0079] Preferably, the reducing agent in the liquid-phase chemical reduction method is selected from one or more of sodium borohydride, hydrazine hydrate, and ethylene glycol.

[0080] More preferably, the reducing agent in the liquid-phase chemical reduction method is sodium borohydride.

[0081] Preferably, the concentration of the reducing agent is selected from any value or range between 0.05-0.5 mol / L, specifically from: 0.05 mol / L, 0.06 mol / L, 0.08 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, 0.5 mol / L, or any range between two of them.

[0082] More preferably, the concentration of the reducing agent is selected from any value or range between 0.05-0.3 mol / L.

[0083] More preferably, the concentration of the reducing agent is selected from any value or range between 0.08-0.1 mol / L.

[0084] More preferably, the concentration of the reducing agent is 0.1 mol / L.

[0085] Preferably, the specific operation of the liquid-phase chemical reduction method is as follows: adding a reducing agent aqueous solution dropwise under stirring conditions, filtering after reaction, washing three times alternately with deionized water and ethanol, and drying.

[0086] Preferably, the temperature of the low-temperature thermal reduction method is selected from any value or range between 300-400℃, specifically from: 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃ or any two of them.

[0087] More preferably, the temperature of the low-temperature thermal reduction method is selected from any value or range between 300-350℃, specifically from: 300℃, 310℃, 320℃, 330℃, 340℃, 350℃ or any two of them.

[0088] More preferably, the temperature of the low-temperature thermal reduction method is 350°C.

[0089] Preferably, the restoration time is selected from any value or range between 1 and 4 hours, specifically from: 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours or any two of them.

[0090] More preferably, the reduction time is selected from any value or range between 2 and 4 hours.

[0091] More preferably, the reduction time is 2 hours.

[0092] Preferably, the copper source is selected from one or more of copper chloride or copper acetate.

[0093] Preferably, the amount of copper source added is selected from any value or range between 10% and 50% of the mass of the hydrophobic porous carbon support, specifically from: 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or any two of these ranges.

[0094] More preferably, the amount of copper source added is selected from any value or range between 10% and 30% of the mass of the hydrophobic porous carbon support.

[0095] More preferably, the amount of copper source added is 10% of the mass of the hydrophobic porous carbon support.

[0096] Based on further solutions to the technical problems of the present invention, or simultaneous solutions to multiple technical problems, the preferred solution in the technical solution provided in the first aspect of the present invention includes:

[0097] The first preferred solution is a method for preparing a fluorine-doped hydrophobic porous carbon-supported copper catalyst. This solution addresses the technical problem that "copper active components are prone to agglomeration or being embedded in the carbon layer during high-temperature one-step pyrolysis," and further solves the technical problems that "the pore structure of the carbon support is underdeveloped, the surface fluorine doping sites are severely lost, gas transport is restricted in the liquid-phase reaction system due to the hydrophilicity of the interface, and there is competition from side reactions."

[0098] Secondly, the present invention provides a fluorine-doped hydrophobic porous carbon-supported copper catalyst prepared by the above-described preparation method.

[0099] Thirdly, the present invention provides the application of a fluorine-doped hydrophobic porous carbon-supported copper catalyst prepared by the above-described preparation method, or the above-described fluorine-doped hydrophobic porous carbon-supported copper catalyst, in the preparation of gas diffusion electrodes or electrocatalytic reaction devices.

[0100] Examples 1-5 of this invention at least support the protection scope of the composition and proportion of the anhydride monomer mixture in the claims.

[0101] Regarding claim 1: the ratio of the mixture of amine monomers and acid anhydride monomers, the composition and ratio of the acid anhydride monomer mixture, and the sintering temperature during the preparation of the hydrophobic porous carbon support.

[0102] The technical feature “the molar ratio of the mixture of amine monomers and acid anhydride monomers is 1:1.4-1.6” is summarized from the common feature “the ratio of the mixture of amine monomers and acid anhydride monomers”, which is 1:1.4, 1:1.5, 1:1.6, etc., as explained above and / or in Examples 1-5. Therefore, those skilled in the art can reasonably presume that the subordinate concept of the technical feature "the molar ratio of the mixture of amine monomers and acid anhydride monomers is 1:1.4-1.6" and its essentially equivalent technical means, as well as technical means that can replace "the molar ratio of the mixture of amine monomers and acid anhydride monomers is 1:1.4-1.6" based on existing technical levels and conventional technical means and common knowledge, should all fall within the protection scope of the ratio relationship of the mixture of amine monomers and acid anhydride monomers in the claims. For example, if other technical features remain unchanged, replacing "the molar ratio of the mixture of amine monomers and acid anhydride monomers is 1:1.4-1.6" with a molar ratio of amine monomers and acid anhydride monomers of 1:1.45, etc., still falls within the protection scope of the ratio relationship of the mixture of amine monomers and acid anhydride monomers in the claims of this invention.

[0103] The technical feature “the mixture of acid anhydride monomers is a mixture of pyromellitic dianhydride and 4,4'-(hexafluoroisopropylidene) phthalic anhydride in a molar ratio of 7-8:2-3” is summarized from the aforementioned explanation and / or the corresponding technical features in Examples 1-5, such as the molar ratio of pyromellitic dianhydride and 4,4'-(hexafluoroisopropylidene) phthalic anhydride being 7:3, 8:2, etc., and is derived from the common feature “the composition and proportioning relationship of the acid anhydride monomer mixture”. Therefore, based on reasonable presumption, those skilled in the art can determine that the technical feature "the mixture of acid anhydride monomers is a mixture of pyromellitic dianhydride and 4,4'-(hexafluoroisopropylidene) phthalic anhydride in a molar ratio of 7-8:2-3", the subordinate concept and its essentially equivalent technical means, and the technical means that can replace "the mixture of acid anhydride monomers is a mixture of pyromellitic dianhydride and 4,4'-(hexafluoroisopropylidene) phthalic anhydride" within the scope of conventional technical means and common knowledge based on the existing level of technology, should all belong to the rights and interests of the user. The scope of protection for the composition and proportion of the anhydride monomer mixture in the claims can be extended, for example, by replacing "the anhydride monomer mixture is a mixture of pyromellitic dianhydride and 4,4'-(hexafluoroisopropylidene) phthalic anhydride in a molar ratio of 7-8:2-3" with "the anhydride monomer mixture is a mixture of pyromellitic dianhydride and 4,4'-(hexafluoroisopropylidene) phthalic anhydride in a molar ratio of 8:3" with the same technical features. This still falls within the scope of protection for the composition and proportion of the anhydride monomer mixture in the claims of this invention.

[0104] The technical feature "sintering temperature of 700-900℃" is derived from the foregoing explanation and / or the corresponding technical features of 700℃, 800℃, and 900℃ in Examples 1-5, summarized by the common feature "sintering temperature during the preparation of hydrophobic porous carbon support". Therefore, those skilled in the art can reasonably infer that the technical feature "sintering temperature of 700-900℃", its subordinate concepts and their essentially equivalent technical means, and technical means that can replace "sintering temperature of 700-900℃" based on existing technology and conventional technical means and common knowledge, should all fall within the protection scope of the sintering temperature in the claims. For example, replacing "sintering temperature of 700-900℃" with a sintering temperature of 850℃ while keeping other technical features unchanged still falls within the protection scope of the sintering temperature in the claims of this invention.

[0105] The beneficial effects of this invention are as follows:

[0106] The present invention has at least the following beneficial effects:

[0107] 1. This invention successfully constructs a porous carbon support with an endogenously hydrophobic surface through a fluorinated monomer copolymerization strategy. Unlike physically mixed insulating hydrophobic agents (such as polytetrafluoroethylene), this invention utilizes the genetic effect during high-temperature pyrolysis to in-situ modify the conductive carbon framework surface with highly thermally stable semi-ionic or aromatic carbon-fluorine bonds. This chemically bonded hydrophobic modification not only endows the material with durable anti-wetting ability (contact angle >100°) and effectively improves the gas transport environment at the gas-liquid-solid three-phase interface, but also avoids the damage to the conductive network of the carbon material caused by external insulating components, achieving a synergy between high conductivity and excellent surface hydrophobicity.

[0108] 2. The stepwise preparation strategy of "high-temperature sintering to reconstruct the support first, followed by liquid-phase loading of the metal" employed in this invention significantly improves the dispersion and utilization rate of the copper active component. Addressing the shortcomings of traditional one-step pyrolysis methods, which easily lead to metal particle agglomeration or encapsulation by thick carbon layers, this invention utilizes a pre-constructed fluorinated porous carbon framework and abundant triazine ring-derived nitrogen sites to anchor the copper precursor. This process ensures that copper metal is highly dispersed in nanoclusters or single atoms on the surface of the support and the inner surface of the pores, maximizing the electrochemical active area while effectively utilizing the well-developed porous structure of the support to promote reaction mass transfer.

[0109] 3. The catalyst prepared by this invention has excellent structural tunability. By adjusting the copolymerization ratio of fluorinated monomers and the pyrolysis temperature, the specific surface area of ​​the support can be flexibly controlled, thereby adapting to the microscopic reaction environment requirements of different catalytic reactions. Attached Figure Description

[0110] Figure 1 The image shown is a scanning electron microscope (SEM) image of the hydrophobic porous carbon support (sintered at 900℃ for 5h) prepared in Example 4 of this invention. The SEM values ​​are: EHT = 15.00kv, WD = 5.9mm, Signal A = SE2, and Mag = 50,000x.

[0111] Figure 2 The X-ray photoelectron spectroscopy (XPS) spectrum of the fluorine-doped hydrophobic porous carbon-supported copper catalyst prepared in Example 4 of this invention is shown, where red represents the number of scan points (net count) and green represents the baseline (background line). Detailed Implementation

[0112] The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way. The following content is merely an exemplary description of the scope of protection claimed by the present invention, and those skilled in the art can make various changes and modifications to the present invention based on the disclosed content, and such changes should also fall within the scope of protection claimed by the present invention.

[0113] The present invention will be further described below by way of specific embodiments. All instruments, devices, equipment, reagents, products, etc., used in the embodiments of the present invention are obtained through conventional commercial means unless otherwise specified. The reagents mainly involved in the embodiments and comparative examples of the present invention are shown in Table 1.

[0114] Table 1

[0115]

[0116] Example 1: Fluorine-doped hydrophobic porous carbon-supported copper catalyst

[0117] The preparation method includes the following steps:

[0118] (1) A mixture of 1,3,5-tris(4-aminophenyl)benzene (TAPB), pyromellitic dianhydride (PMDA), and 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA) was dissolved in a mixed solvent system of acetone and ethanol with a volume ratio of 10:1; wherein the molar ratio of the amine monomer (TAPB) to the anhydride monomer mixture (the sum of PMDA and 6FDA) was 1:1.6; and the molar ratio of pyromellitic dianhydride to 4,4'-(hexafluoroisopropylidene)phthalic anhydride in the anhydride monomer mixture was 7:3; the mixture was stirred at -10℃ and subjected to precipitation polymerization for 4 h. After the reaction was completed, the mixture was centrifuged at 1000 r / min for 10 min (or filtered), washed 3 times with ethanol, and dried at 60℃ for 12 h to obtain polyimide precursor powder;

[0119] (2) The polyimide precursor powder was placed in a tube furnace and sintered at 700°C at a rate of 10°C / min in a nitrogen atmosphere. The temperature was kept constant for 2 hours and then cooled to 25°C to obtain a hydrophobic porous carbon support.

[0120] (3) Disperse 0.1g of hydrophobic porous carbon support in 20mL of isopropanol, add 0.01g of copper chloride, stir to make the copper source uniformly adsorbed on the surface and inside the pores of the support, stir for 6h, then remove the isopropanol to obtain powder A, and then carry out a low temperature thermal reduction reaction at 300℃ for 2h in a hydrogen atmosphere (5% H2 / Ar) to obtain the final product.

[0121] Example 2 Fluorine-doped hydrophobic porous carbon-supported copper catalyst

[0122] The preparation method includes the following steps:

[0123] (1) A mixture of 1,3,5-tris(4-aminophenyl)benzene (TAPB), pyromellitic dianhydride (PMDA), and 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA) was dissolved in a mixed solvent system of acetone and ethanol with a volume ratio of 10:1; wherein the molar ratio of the amine monomer (TAPB) to the anhydride monomer mixture (the sum of PMDA and 6FDA) was 1:1.4; and the molar ratio of pyromellitic dianhydride to 4,4'-(hexafluoroisopropylidene)phthalic anhydride in the anhydride monomer mixture was 7:3; the mixture was stirred at 10°C and subjected to precipitation polymerization for 4 h. After the reaction was completed, the mixture was centrifuged at 1000 r / min for 10 min (or filtered), washed three times with ethanol, and dried at 60°C for 12 h to obtain polyimide precursor powder;

[0124] (2) The polyimide precursor powder was placed in a tube furnace and sintered at 700°C at a rate of 10°C / min in a nitrogen atmosphere. The temperature was kept constant for 2 hours and then cooled to 25°C to obtain a hydrophobic porous carbon support.

[0125] (3) Disperse 0.1 g of hydrophobic porous carbon support in 20 mL of isopropanol, add 0.01 g of copper chloride, and stir to ensure that the copper source is uniformly adsorbed on the surface and inside the pores of the support. Under continuous stirring, slowly add 5 mL of 0.1 mol / L sodium borohydride aqueous solution, react for 2 h, filter, wash alternately with deionized water and ethanol, and finally dry in a vacuum drying oven at 60 °C for 12 h to obtain the final product.

[0126] Example 3 Fluorine-doped hydrophobic porous carbon-supported copper catalyst

[0127] (1) A mixture of 1,3,5-tris(4-aminophenyl)benzene (TAPB), pyromellitic dianhydride (PMDA), and 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA) was dissolved in a mixed solvent system of acetone and ethanol with a volume ratio of 10:1; wherein the molar ratio of the amine monomer (TAPB) to the anhydride monomer mixture (the sum of PMDA and 6FDA) was 1:1.5; and the molar ratio of pyromellitic dianhydride to 4,4'-(hexafluoroisopropylidene)phthalic anhydride in the anhydride monomer mixture was 8:2; the mixture was stirred at 0°C and subjected to precipitation polymerization for 4 h. After the reaction was completed, the mixture was centrifuged at 1000 r / min for 10 min (or filtered), washed three times with ethanol, and dried at 60°C for 12 h to obtain polyimide precursor powder;

[0128] (2) The polyimide precursor powder was placed in a tube furnace and sintered at 900°C at a rate of 10°C / min in a nitrogen atmosphere. The temperature was kept constant for 3 hours and then cooled to 25°C to obtain a hydrophobic porous carbon support.

[0129] (3) Disperse 0.1g of hydrophobic porous carbon support in 20mL of isopropanol, add 0.01g of copper chloride, stir to make the copper source uniformly adsorbed on the surface and inside the pores of the support, stir for 6h, then remove the isopropanol to obtain powder A, and then carry out a low temperature thermal reduction reaction at 350℃ for 2h in a hydrogen atmosphere (5% H2 / Ar) to obtain the final product.

[0130] Example 4 Fluorine-doped hydrophobic porous carbon-supported copper catalyst

[0131] (1) A mixture of 1,3,5-tris(4-aminophenyl)benzene (TAPB), pyromellitic dianhydride (PMDA), and 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA) was dissolved in a mixed solvent system of acetone and ethanol with a volume ratio of 10:1; wherein the molar ratio of the amine monomer (TAPB) to the anhydride monomer mixture (the sum of PMDA and 6FDA) was 1:1.5; and the molar ratio of pyromellitic dianhydride to 4,4'-(hexafluoroisopropylidene)phthalic anhydride in the anhydride monomer mixture was 8:2; the mixture was stirred at 0°C and subjected to precipitation polymerization for 4 h. After the reaction was completed, the mixture was centrifuged at 1000 r / min for 10 min (or filtered), washed three times with ethanol, and dried at 60°C for 12 h to obtain polyimide precursor powder;

[0132] (2) The polyimide precursor powder was placed in a tube furnace and sintered at 900°C at a rate of 10°C / min in a nitrogen atmosphere. The temperature was kept constant for 5 hours and then cooled to 25°C to obtain a hydrophobic porous carbon support.

[0133] (3) Disperse 0.1g of hydrophobic porous carbon support in 20mL of isopropanol, add 0.01g of copper chloride, stir to make the copper source uniformly adsorbed on the surface and inside the pores of the support, stir for 6h, then remove the isopropanol to obtain powder A, and then carry out a low temperature thermal reduction reaction at 350℃ for 2h in a hydrogen atmosphere (5% H2 / Ar) to obtain the final product.

[0134] Example 5 Fluorine-doped hydrophobic porous carbon-supported copper catalyst

[0135] (1) A mixture of 1,3,5-tris(4-aminophenyl)benzene (TAPB), pyromellitic dianhydride (PMDA), and 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA) was dissolved in a mixed solvent system of acetone and ethanol with a volume ratio of 10:1; wherein the molar ratio of the amine monomer (TAPB) to the anhydride monomer mixture (the sum of PMDA and 6FDA) was 1:1.5; and the molar ratio of pyromellitic dianhydride to 4,4'-(hexafluoroisopropylidene)phthalic anhydride in the anhydride monomer mixture was 8:2; the mixture was stirred at 0°C and subjected to precipitation polymerization for 4 h. After the reaction was completed, the mixture was centrifuged at 1000 r / min for 10 min (or filtered), washed three times with ethanol, and dried at 60°C for 12 h to obtain polyimide precursor powder;

[0136] (2) The polyimide precursor powder was placed in a tube furnace and sintered at 800°C at a rate of 10°C / min in a nitrogen atmosphere. The temperature was kept constant for 2 hours and then cooled to 25°C to obtain a hydrophobic porous carbon support.

[0137] (3) Disperse 0.1g of hydrophobic porous carbon support in 20mL of isopropanol, add 0.01g of copper chloride, stir to make the copper source uniformly adsorbed on the surface and inside the pores of the support, stir for 6h, then remove the isopropanol to obtain powder A, and then carry out a low temperature thermal reduction reaction at 350℃ for 2h in a hydrogen atmosphere (5% H2 / Ar) to obtain the final product.

[0138] Comparative Example 1

[0139] The difference from Example 4 is that 4,4'-(hexafluoroisopropylidene) phthalic anhydride is not added in step (1), but pyromellitic dianhydride (i.e., the molar ratio of amine monomer to PMDA is 1:1.5) is used to prepare a fluorine-free polyimide precursor. The remaining steps and amounts are the same as in Example 4.

[0140] Comparative Example 2

[0141] Unlike Example 4, the preparation method is different.

[0142] The preparation method of Comparative Example 2 is as follows: commercially available activated carbon powder, polytetrafluoroethylene emulsion (PTFE) and copper chloride are directly mixed.

[0143] Specifically, 0.1g of activated carbon was dispersed in 20mL of isopropanol, and 0.01g of copper chloride and PTFE emulsion equivalent to 10% of the mass of activated carbon were added. After ultrasonic dispersion for 30min, the solvent was stirred and evaporated. Finally, the mixture was reduced at 350℃ in a hydrogen-containing atmosphere for 2h to obtain a physically mixed hydrophobic modified catalyst.

[0144] Comparative Example 3

[0145] The difference from Example 4 is that the high-temperature sintering process in step (2) is omitted, and the polyimide precursor powder obtained in step (1) is directly used for copper loading and reduction in step (3) of the original Example 4.

[0146] Comparative Example 4

[0147] The difference from Example 4 is that the molar ratio of the amine monomer and the anhydride monomer mixture is replaced by 1:2.5, while the remaining steps and amounts are the same as in Example 4.

[0148] Comparative Example 5

[0149] The difference from Example 4 is that the molar ratio of the amine monomer and the anhydride monomer mixture is replaced by 1.5:1, while the other steps and amounts are the same as in Example 4.

[0150] Comparative Example 6

[0151] The difference from Example 4 is that the 1,3,5-tris(4-aminophenyl)benzene (TAPB), pyromellitic dianhydride (PMDA), and 4,4'-(hexafluoroisopropylidene) phthalic anhydride (6FDA) in a molar ratio of 1:1.5 are replaced with 4,4'-diaminodiphenyl ether (ODA) and pyromellitic dianhydride (PMDA) in a molar ratio of 1:1.

[0152] Specifically:

[0153] (1) A mixture of 4,4'-diaminodiphenyl ether (ODA) and pyromellitic dianhydride (PMDA) in a molar ratio of 1:1 was dissolved in a mixed solvent system of acetone and ethanol in a volume ratio of 10:1. The precipitation polymerization reaction was carried out at 0°C for 4 h. After the reaction was completed, the mixture was centrifuged at 1000 r / min for 10 min, washed, and dried at 60°C for 12 h to obtain ordinary polyimide powder.

[0154] The subsequent steps (2) and (3) are the same as in Example 4.

[0155] Comparative Example 7

[0156] The difference from Example 4 is that the sintering temperature in step (2) is replaced with 600°C, while the other steps and amounts are the same as in Example 4.

[0157] Comparative Example 8

[0158] The difference from Example 4 is that the sintering temperature in step (2) is replaced with 950°C, while the other steps and amounts are the same as in Example 4.

[0159] Comparative Example 9

[0160] The difference from Example 4 is that the molar ratio of pyromellitic dianhydride and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride is replaced with 6:4. All other steps and amounts are the same as in Example 4.

[0161] Example 1: Performance Characterization of Fluorine-Doped Hydrophobic Porous Carbon-Supported Copper Catalyst

[0162] 1. Experimental Methods

[0163] (1) Specific surface area determination: The specific surface area and porosity analyzer of the American Micron Instruments Company was used for determination. Before the test, the sample to be tested was degassed at 150℃ for 6 hours under vacuum to remove adsorbed impurities. Then, nitrogen adsorption-desorption isotherm test was carried out at liquid nitrogen temperature of 77K. The specific surface area was calculated in the range of relative pressure of 0.05-0.30 (dimensionless relative pressure) using a multi-point BET model, and the pore volume and pore size distribution were analyzed using a DFT model.

[0164] (2) Surface water contact angle: The contact angle was measured using a DSA100 optical contact angle measuring instrument from Krüss GmbH, Germany. Approximately 20 mg of catalyst powder was pressed into a flat disc under a pressure of 10 MPa and placed on the sample stage. At room temperature, 5 μL of deionized water was added to the surface of the sample disc using a microsyringe. After standing for 5 seconds to allow the droplet to stabilize, the contact angle between the droplet and the solid surface was measured using the circular fitting method provided with the instrument. Five different locations were measured for each sample, and the average value was taken.

[0165] (3) Surface element content and metal valence state: The surface element content and metal valence state were characterized using an ESCALAB 250Xi X-ray photoelectron spectrometer from Thermo Fisher Scientific. Monochromatic Al Kα rays were used as the excitation source. The binding energy data of all elements were corrected for charge using the C 1s peak of contaminated carbon at 284.8 eV. The high-resolution spectra of Cu 2p, N 1s and F 1s were analyzed by peak fitting using XPS Peak software to analyze the chemical environment and valence state distribution of each element.

[0166] 2. Experimental Results

[0167] from Figure 1 As can be seen, after sintering and reconstruction, the material exhibits a rough particle accumulation morphology and rich micro-nano pore structure. This rough interface with high specific surface area is beneficial to the subsequent adsorption anchoring and high dispersion loading of copper active components.

[0168] according to Figure 2X-ray photoelectron spectroscopy characterization further confirmed the chemical environment and valence state distribution of the catalyst surface elements. Peak fitting of the F 1s high-resolution spectrum showed that fluorine was successfully doped and modified on the conductive carbon framework surface in the form of semi-ionic carbon-fluorine bonds or aromatic carbon-fluorine bonds. This chemical bonding state endows the porous carbon support with stable endogenous hydrophobic characteristics.

[0169] Comparative analysis of the BET characterization data in Table 2 shows that this invention successfully solved the technical challenge of simultaneously achieving high specific surface area and hydrophobicity in carbon-based supports through molecular structure design and pyrolysis process control. The introduction of the fluorinated monomer (4,4'-(hexafluoroisopropylidene) phthalic anhydride) played a decisive role in expanding the pore structure of the carbon support. Comparing the experimental data of Example 4 and Comparative Example 1, it can be found that under the same sintering conditions of 900℃ and 5 hours, the specific surface area of ​​the carbon support prepared using the non-fluorinated anhydride monomer was only 513.6 m² / g, while the specific surface area of ​​the carbon support after introducing the fluorinated anhydride monomer jumped to 1224.3 m² / g, an increase of more than two times. This significant difference strongly demonstrates that the large trifluoromethyl (-CF3) groups in the polymer chain segments produce a significant steric hindrance effect. This rigid and large side group effectively prevents the excessively dense packing of aromatic carbon layers during high-temperature reconstruction, thereby opening up more free volume inside the carbon skeleton and forming a rich and well-developed microporous structure. This endogenous pore-expansion mechanism not only endows the material with excellent hydrophobic properties, but also unexpectedly and significantly increases the loading space of active sites.

[0170] Secondly, precise control of high-temperature pyrolysis process parameters, especially the extension of isothermal time, is crucial for the in-depth exploration of microporous structures. Data from the catalysts prepared in Examples 3 and 4 show that when the pyrolysis temperature is maintained at 900℃, as the isothermal treatment time is extended from 3 hours to 5 hours, the specific surface area of ​​the material further increases from 786.4 m² / g to 1224.3 m² / g, and the total pore volume also increases significantly. This indicates that, at the high-temperature stage, appropriately extending the heat treatment time is beneficial for the complete pyrolysis of the polymer precursor and the deep escape of small molecule gases. This process further etches and enriches the pore channels of the carbon substrate, achieving precise control of the pore structure. Meanwhile, comparing Comparative Example 3 (specific surface area only 34.6 m² / g) without high-temperature treatment with Example 4, it is clear that the specific high-temperature reconstruction process of this invention is a necessary condition for transforming non-porous polymers into highly active porous carbon supports. Only through high-temperature pore formation can sufficient dispersion sites and mass transfer channels be provided for the copper active components.

[0171] Finally, the chemical in-situ doping strategy employed in this invention has significant technical advantages over traditional physical mixing modification. While the catalyst prepared in Comparative Example 2 could also acquire a high hydrophobic angle (132 degrees) through physical mixing with polytetrafluoroethylene (PTFE), the physical filling behavior of PTFE, being an insulating and non-porous polymer, severely blocked the original microporous channels of the carbon support, causing the specific surface area of ​​Comparative Example 2 to drop sharply to 350.0 m² / g. In contrast, this invention, through chemical bonding, in-situ modifies fluorine atoms onto the carbon framework, achieving a hydrophobic modification with a surface contact angle of 115 degrees while perfectly preserving and even enhancing the pore structure of the material. This successfully constructs a three-phase reaction interface that combines high conductivity, high specific surface area, and excellent hydrophobicity, effectively solving the mass transfer limitation problem caused by solvent competitive adsorption in liquid-phase reactions.

[0172] Table 2

[0173]

[0174] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a fluorine-doped hydrophobic porous carbon-supported copper catalyst, characterized in that, Includes the following steps: Polyimide precursor powder was prepared using a mixture of amine monomers and acid anhydride monomers as raw materials; then the polyimide precursor powder was sintered and reconstructed to obtain a fluorine-nitrogen co-doped hydrophobic porous carbon support; finally, copper active components were loaded onto the hydrophobic porous carbon support. The molar ratio of the mixture of amine monomers and acid anhydride monomers is 1:1.4-1.6; The anhydride monomer mixture is a mixture of pyromellitic dianhydride and 4,4'-(hexafluoroisopropylidene) phthalic anhydride in a molar ratio of 7-8:2-3. The sintering temperature is 700-900℃.

2. The preparation method according to claim 1, characterized in that, The preparation of the polyimide precursor powder includes the following steps: The mixture of amine monomers and acid anhydride monomers is dissolved in a solvent, stirred, and after the reaction is complete, centrifuged, washed, and dried to obtain the final product.

3. The preparation method according to claim 2, characterized in that, The amine monomers are selected from one or more of 1,3,5-tris(4-aminophenyl)benzene and 4,4'-diaminodiphenyl ether.

4. The preparation method according to claim 2, characterized in that, The solvent is selected from one or more of acetone, ethanol, butanone, and ethyl acetate.

5. The preparation method according to claim 2, characterized in that, The temperature of the stirring reaction is -10~10℃.

6. The preparation method according to claim 1, characterized in that, The sintering reconstruction includes the following steps: The polyimide precursor powder was sintered in an inert atmosphere, kept at a constant temperature, and then cooled. The sintering time is 2-5 hours.

7. The preparation method according to claim 1, characterized in that, The process of loading copper active components onto a hydrophobic porous carbon support includes the following steps: The hydrophobic porous carbon support is dispersed in solvent A, a copper source is added, and after stirring, solvent A is removed to obtain powder A, which is then reduced to obtain the final product.

8. The preparation method according to claim 7, characterized in that, The reduction method is either liquid-phase chemical reduction or low-temperature thermal reduction. The copper source is selected from one or more of copper chloride or copper acetate.

9. A fluorine-doped hydrophobic porous carbon-supported copper catalyst prepared by the preparation method according to any one of claims 1-8.

10. The application of the fluorine-doped hydrophobic porous carbon-supported copper catalyst prepared by the preparation method according to any one of claims 1-8 in the preparation of gas diffusion electrodes or electrocatalytic reaction devices.

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