A copper framework composite catalytic material and a preparation method and application thereof

Abstract

The application discloses a copper framework composite catalytic material and a preparation method and application thereof, and belongs to the technical field of catalytic materials.The copper framework composite catalytic material is prepared by a four-step in-situ construction method of chemical oxidation, baking, hydrogen reduction and electrodeposition, and is a copper framework / ternary alloy catalytic material.The application prepares a high-performance copper framework catalytic electrode through the in-situ construction strategy, reveals the structure-activity relationship between the micro-nano structure of the copper framework catalytic electrode and the catalytic performance under different synthesis conditions, explores the dynamic reconstruction and reaction path of the catalytic electrode through various in-situ characterization technologies and theoretical calculation, and investigates the service behavior of the electrode under severe working conditions.The application provides a theoretical basis for the design of high-performance water electrolysis catalysts, and has a positive significance for promoting the large-scale development of the green hydrogen industry.

Description

Technical Field

[0001] This invention belongs to the field of catalytic materials technology, and particularly relates to a copper-framework composite catalytic material, its preparation method, and its application. Background Technology

[0002] With the escalating global energy crisis and the ongoing energy transition, developing efficient and clean hydrogen energy technologies has become a key approach to addressing fossil fuel depletion and environmental challenges. Hydrogen energy is characterized by its green and low-carbon nature, wide availability, and broad applications, and can be coupled with various types of industries. Developing efficient and clean hydrogen production technologies is of great significance for building a new energy system and cultivating new productive forces. As an important component of hydrogen production pathways, water electrolysis has attracted considerable attention due to its zero-carbon emission hydrogen production, large-scale green hydrogen production, and ability to meet industrial demands.

[0003] The catalytic electrode for water electrolysis is the core of an alkaline electrolyzer for hydrogen production. Researching advanced catalytic electrodes can reduce the hydrogen and oxygen evolution overpotentials, ultimately achieving energy savings. Therefore, the rational design of the catalytic substrate for water electrolysis can drive improvements in water electrolysis efficiency. Currently, alkaline electrolyzers still heavily rely on precious metal-based catalysts such as platinum and iridium, whose high cost and limited reserves restrict large-scale industrial applications. Therefore, there is an urgent need to develop non-precious metal catalytic electrodes that combine high activity, high stability, and low cost.

[0004] Transition metal materials (such as nickel, iron, cobalt, and copper) exhibit excellent catalytic potential due to their abundant reserves, low cost, and tunable electronic structure, making them an important direction for replacing precious metal catalysts and promoting the industrialization of hydrogen production through water electrolysis. In large-scale electrolysis equipment, the cost, efficiency, and operational life of the catalytic electrode directly affect the economic feasibility of hydrogen production. Currently, the scientific and industrial communities are actively seeking non-precious metal catalytic materials that combine high activity and high stability to reduce equipment investment and operating costs. Through micro / nano structure design and interface optimization, transition metal catalytic electrodes can achieve sustained and efficient catalytic performance at near-industrial current densities, making their transition from scientific synthesis to industrial application possible.

[0005] In recent years, copper-based substrates have attracted widespread attention in the field of water electrolysis catalysis due to their low cost, excellent electrical and thermal conductivity, and abundant redox states. However, the intrinsic catalytic activity of copper electrodes is relatively low, and they are prone to performance degradation and corrosion dissolution under harsh conditions such as strong alkali and high potential, which limits their practical application under high current and long-term operating conditions. Most reported electrocatalysts for water electrolysis are synthesized in powder form, usually involving the application of binders (e.g., QPPO, Nafion, PTFE) in the electrolyte, which can be directly coated onto the substrate. However, the use of binders inevitably covers the active sites and generates significant contact resistance, which ultimately leads to low conductivity and limits mass transport due to the negative impact of the damaged microstructure. Therefore, developing effective structural composition control strategies to improve the activity and durability of copper-based catalytic electrodes has become a key measure to promote their large-scale application. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a copper-framework composite catalytic material, its preparation method, and its application.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing a copper-framework composite catalytic material, comprising the following steps: The pretreated copper foam was immersed in a chemical oxidation solution for alkaline etching. The blue product obtained by alkaline etching was calcined in air. After cooling to room temperature, the black product obtained by calcination was reduced with hydrogen to obtain copper nanoframework. A nickel-iron-cobalt ternary alloy catalytic layer was loaded onto the copper nanoframework using a constant current electrodeposition process to obtain the copper-framework composite catalytic material. When using constant current for electrodeposition, the electrodeposition time is 5–20 min, and the current density is -20 to -40 mA·cm⁻¹. -2 .

[0008] The copper-framework composite catalytic material of this invention is a copper-framework / ternary alloy catalytic material. This material uses copper foam as the framework substrate and is prepared through a four-step in-situ construction method involving chemical oxidation, calcination, hydrogen reduction, and electrodeposition. The intrinsic catalytic activity of pure copper is far lower than that of nickel, platinum, iridium, and other catalytic materials. In the oxygen evolution reaction, pure copper has a high reaction barrier and cannot effectively stabilize the reaction. * O or * Key intermediates such as OOH lead to high energy consumption during electrocatalysis, limiting its application in water electrolysis. Furthermore, pure copper is not thermodynamically absolutely stable; at higher potentials, the pure copper electrode body is easily oxidized to Cu. 2+Furthermore, the dissolved substances enter the electrolyte, causing the material structure to collapse and making it unsuitable for long-term service. Therefore, addressing these advantages and disadvantages, this invention achieves complementary advantages between the copper framework substrate and the nickel-iron group transition metal catalyst by in-situ constructing a copper nanoframework and electrodepositing a nickel-iron-cobalt ternary alloy catalytic layer. The optimal synthesis conditions are determined through systematic control of reaction parameters, elucidating the structure-activity relationship between the micro / nano structure of the copper framework catalytic electrode and its electrocatalytic performance. This invention constructs a copper nanoframework in-situ on the surface of foamed copper through a series of redox reactions, calcination, and hydrogen reduction, and then electrodeposits highly active nickel, nickel-iron, and nickel-iron-cobalt catalytic layers. In-situ Raman, in-situ infrared, and in-situ XRD characterization methods, along with DFT theoretical calculations, are used to further understand and analyze the oxygen evolution step and mechanism of the copper framework catalytic electrode in water electrolysis, and industrial simulation conditions are constructed to study the electrode's service behavior. This work provides new theoretical support and practical results for designing efficient, stable, and highly active transition metal alkaline water electrolysis catalytic electrodes.

[0009] Furthermore, the chemical oxidizing solution is composed of water, ammonium persulfate, and sodium hydroxide.

[0010] Furthermore, in the chemical oxidation solution, the concentration of ammonium persulfate is 0.125 M, and the concentration of sodium hydroxide is 2.5 M.

[0011] Furthermore, the alkaline etching time is 20 minutes.

[0012] Furthermore, the baking treatment is performed at a temperature of 180°C for a time of 60 minutes.

[0013] Furthermore, the hydrogen reduction temperature is 285°C, the time is 150 min, and the argon and hydrogen flow rates are 180 sccm and 20 sccm, respectively.

[0014] Furthermore, the pH of the electrodeposition plating solution is 3~4.

[0015] Furthermore, the electrodeposition plating solution is composed of water, nickel nitrate hexahydrate, ferrous sulfate heptahydrate, cobalt nitrate hexahydrate, sodium citrate dihydrate, boric acid, and sodium nitrate.

[0016] Furthermore, in the electrodeposition plating solution, the concentrations of nickel nitrate hexahydrate, ferrous sulfate heptahydrate, cobalt nitrate hexahydrate, sodium citrate dihydrate, boric acid, and sodium nitrate are 0.15 M to 0.3 M.

[0017] The present invention also provides a copper-framework composite catalytic material prepared according to the above method.

[0018] The present invention also provides an application of the above-mentioned copper-framework composite catalytic material in oxygen evolution through water electrolysis.

[0019] Compared with the prior art, the present invention has the following advantages and technical effects: To address the key issues of insufficient intrinsic activity, limited service stability, and susceptibility to structural degradation under harsh conditions such as strong alkali and high potential in copper-based catalytic materials, this invention proposes an iterative design concept to replace traditional nickel-based supports with copper-based nanoframeworks. An in-situ construction strategy of redox coupled electrodeposition is developed. Through multi-scale in-situ characterization and first-principles calculations, the influence mechanisms of copper nanoframework structure regulation, interface electron optimization, and the synergistic effect of loaded nickel, iron, and cobalt elements on the evolution of the active phase, reaction pathway regulation, and service stability are systematically revealed. Based on this, large-area copper-framework / ternary alloy catalytic electrodes are fabricated on a large scale, and their oxygen evolution behavior is evaluated using a self-equipped simulated industrial alkaline electrolyzer. The main conclusions are as follows: (1) A copper framework / ternary alloy catalytic electrode with a core-shell heterostructure was successfully prepared by a synergistic strategy of in-situ construction of nanoframework and electrodeposition. The regulation of electrode micro / nano structure and oxygen evolution performance by electrodeposition time and current density was systematically investigated. The optimal process parameters were determined to be a deposition time of 20 min and a current density of -20 mA·cm. -2 The electrochemically active area of ​​this catalytic electrode reaches 348.25 cm². 2 The double-layer capacitance is 13.93 mF·cm. -2 This fully demonstrates the unique advantages of multi-level nanoframework structures in terms of active site exposure and charge transport; and at 10 mA·cm -2 and 100mA·cm -2 The overpotentials were 203 mV and 245 mV, respectively, and the Tafel slope was 19.87 mV·dec. -1 It exhibits strong intrinsic activity and excellent reaction kinetics.

[0020] (2) By comparing the oxygen evolution performance of nickel-iron-cobalt ternary alloys loaded on different substrates such as nickel foam, copper foam, and copper nanoframework, the significant advantages of copper nanoframework in terms of multi-level structure, interfacial bonding, and mass transfer channel construction were confirmed. Further, by combining in-situ XRD, in-situ Raman, and in-situ infrared spectroscopy, the active phase evolution and reaction path regulation mechanism of copper framework / ternary alloy catalytic electrodes in the oxygen evolution process were systematically analyzed. In-situ XRD identified the true active phase γ-NiOOH in the oxygen evolution process; in-situ Raman results showed that Fe doping promoted the early formation of the NiOOH active phase, and the introduction of Co induced the vibrational coupling of Ni-O and Co-O and the broadening of the spectral peak, which promoted the formation of the NiFeCoOOH active phase with higher disorder; in-situ infrared results showed that the NiFe system mainly followed the lattice oxygen mechanism (LOM), while the NiFeCo system formed a dual-path synergistic mechanism with adsorbate evolution mechanism (AEM) as the main mechanism and LOM as the auxiliary mechanism. First-principles calculations further show that Co doping significantly reduces the free energy barrier of the AEM rate-determining step (*O→*OOH) from 3.29 eV to 2.16 eV, confirming that multi-element synergistic optimization of the reaction barrier is a key factor in enhancing intrinsic catalytic activity.

[0021] (3) Based on the service behavior of electrodes in industrial electrolyzers, large-area copper framework / ternary alloy catalytic electrodes were fabricated on a large scale, and their industrial service behavior was evaluated using a self-equipped industrial simulated electrolyzer testing system. The results show that within a wide current density range (10~500 mA·cm⁻¹), the large-area copper framework / ternary alloy catalytic electrode was successfully fabricated. -2 The large-area electrode exhibits significantly lower DC power consumption than commercially available double Raney nickel electrodes, demonstrating superior energy conversion efficiency. Furthermore, in step stability tests simulating industrial fluctuating currents, the copper-framework catalytic electrode withstood multiple alternating high current density shocks, exhibiting small voltage fluctuations and rapid recovery, demonstrating overall operational stability far superior to commercial nickel mesh electrodes. These results fully demonstrate that the developed large-scale preparation strategy effectively maintains the advantages of the multi-level copper framework structure, and the fabricated electrode combines low energy consumption and high stability in industrial-grade alkaline electrolyzers, providing reliable technical support for the practical engineering application of non-precious metal catalytic electrodes. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a flowchart of the in-situ construction of the copper nanoframework and the loaded active layer in Example 1; Figure 2 Optical and SEM images of each stage of the copper nanowire skeleton construction process in Example 1 are shown. (a) is an optical image and (b) is an SEM image. In (b), the upper scale bar is 1 μm and the lower scale bar is 10 μm. Figure 3 The images are SEM images of the copper-framework composite catalytic material in Example 1 at different magnifications: (a) is 1 μm and (b) is 200 nm. Figure 4 XRD patterns of different electrode materials and copper-framework composite catalyst (NW@NiFeCo) in Example 1 are shown. (a) Cu NW@NiFeCo, Cu NW@NiFe, Cu NW@Ni, and Cu NW are shown. (b) CP@NiFeCo is shown. Figure 5 In Example 1, (a) is a TEM image of the copper-based composite catalytic material; (b) to (c) are HRTEM images of the copper-based composite catalytic material; (d) is a SAED image of the copper-based composite catalytic material; and (e) to (i) are EDS images of the copper-based composite catalytic material. Figure 6 The following are XPS images of the copper-framework composite catalytic material in Example 1: (a) is the full spectrum, (b) is the Cu 2p spectrum, (c) is the Ni 2p spectrum, (d) is the Fe 2p spectrum, and (e) is the Co 2p spectrum. Figure 7 The following are UPS comparison diagrams of the copper nanoframework substrate, the copper framework composite catalytic material, and the nickel-iron-cobalt ternary alloy catalytic coating (hydrophilic carbon paper substrate) in Example 1: (a) is the copper nanoframework substrate, (b) is the nickel-iron-cobalt ternary alloy catalytic coating (hydrophilic carbon paper substrate), and (c) is the copper framework composite catalytic material in Example 1. Figure 8 SEM images of copper-based composite catalysts at different deposition times: (a) 5 min, (b) 10 min, (c) 20 min, and (d) 30 min. Figure 9 The elemental composition of the copper framework composite catalyst at different deposition times is shown in (a) 5 min, (b) 10 min, (c) 20 min, and (d) 30 min. Figure 10 The following are comparisons of the oxygen evolution performance of copper-based composite catalysts at different deposition times: (a) CV curve, (b) overpotential, (c) Tafel curve, and (d) EIS spectrum. Figure 11 ECSA and C of copper framework composite catalysts at different deposition times dl Comparison charts: (a) 5 min ECSA, (b) 10 min ECSA, (c) 20 min ECSA, (d) 30 min ECSA, (e) C dl Comparison chart; Figure 12 SEM images of copper framework composite catalysts at different deposition current densities are shown. (a) is at 10 mA·cm⁻¹. -2 (b) is 20 mA·cm -2 (c) is 30 mA·cm -2 (d) is 40 mA·cm -2 (e) is 50 mA·cm -2 ; Figure 13 The elemental composition of copper framework composite catalysts under different deposition current densities is shown in (a) at 10 mA·cm⁻¹. -2 (b) is 20 mA·cm -2 (c) is 30 mA·cm -2 (d) is 40 mA·cm -2 (e) is 50 mA·cm -2 ; Figure 14 The following are comparisons of the oxygen evolution performance of copper-framework composite catalysts under different deposition current densities: (a) CV curve, (b) overpotential, (c) Tafel curve, and (d) EIS spectrum. Figure 15 ECSA and C of copper framework composite catalysts under different deposition current densities dl Comparison chart, (a) is 10 mA·cm -2 ECSA, (b) is 20 mA·cm -2 ECSA, (c) is 30 mA·cm -2 ECSA, (d) is 40 mA·cm -2 ECSA, (e) 50 mA·cm -2 ECSA, (f) is C dl Comparison chart; Figure 16 (a) is a comparison diagram of the interfacial performance of copper-framework composite catalytic materials, (b) is the resistivity test result of copper-framework composite catalytic materials, and (c) and (d) are comparison diagrams of the oxygen evolution interface performance of copper-framework composite catalytic materials. Figure 17 Comparison of catalytic performance of copper-nickel, iridium dioxide and other catalytic electrodes: (a) CV curve, (b) Tafel curve, (c) EIS spectrum, (d) TOF spectrum; Figure 18The catalytic performance of the composite catalytic material based on copper foam (CF@NiFeCo), the composite catalytic material based on nickel foam (NF@NiFeCo), and the copper framework composite catalytic material (copper nanoframework@NiFeCo) of Example 1 are compared. (a) is the overpotential, (b) is the CV curve, (c) is the Tafel curve, and (d) is the EIS spectrum. Figure 19 The results are the electrochemical in-situ infrared characterization results of the copper framework composite catalytic material in Example 1; Figure 20 The results are the electrochemical in-situ infrared characterization of the copper-framework composite catalytic material in Comparative Example 1. Figure 21 In the middle (a), the voltage-current density performance curve of the small cell is shown, and (b)~(c) are the comparison of the energy consumption of different electrodes under three current densities. Figure 22 The results are the stability test results of the copper-framework composite catalytic material in Example 1. Detailed Implementation

[0023] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0024] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0025] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0026] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0027] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0028] An embodiment of the present invention provides a method for preparing a copper-framework composite catalytic material, comprising the following steps: Pretreated copper foam was immersed in a chemical oxidizing solution for alkaline etching to grow copper hydroxide nanowires on the surface of the copper foam. The blue product obtained by alkaline etching was calcined in an air atmosphere. After cooling to room temperature, the black product obtained by calcination was reduced with hydrogen to obtain copper (Cu) nanoframework. A nickel-iron-cobalt ternary alloy catalytic layer (Ni-Fe-Co ternary alloy layer) was loaded onto a copper nanoframework using a constant current electrodeposition process to obtain a copper-framework composite catalytic material; When using constant current for electrodeposition, the electrodeposition time is 5–20 min, and the current density is -20 to -40 mA·cm⁻¹. -2 The preferred electrodeposition time is 20 min, and the preferred current density is -20 mA·cm⁻¹. -2 .

[0029] In a preferred embodiment of the present invention, the pretreatment method for foamed copper is as follows: the foamed copper is cut to a suitable size (e.g., 2×5 cm), and then ultrasonically cleaned with 30% dilute hydrochloric acid and acetone for 15 min, followed by ultrasonic cleaning with deionized water for 10 min to remove the oxide layer and organic residues on the surface of the foamed copper; the cleaned foamed copper is then dried with an argon gas gun to obtain pretreated foamed copper.

[0030] In a preferred embodiment of the present invention, the chemical oxidation liquid is composed of water, ammonium persulfate and sodium hydroxide.

[0031] In a preferred embodiment of the present invention, the concentration of ammonium persulfate in the chemical oxidation solution is 0.125 M, and the concentration of sodium hydroxide is 2.5 M.

[0032] In a preferred embodiment of the present invention, the alkaline etching time is 20 min.

[0033] In a preferred embodiment of the present invention, the baking temperature is 180°C and the time is 60 min.

[0034] In a preferred embodiment of the present invention, the hydrogen reduction temperature is 285°C, the time is 150 min, and the flow rates of argon and hydrogen are 180 sccm and 20 sccm, respectively.

[0035] In a preferred embodiment of the present invention, the pH of the electrodeposition plating solution is 3 to 4, preferably 3.5.

[0036] In a preferred embodiment of the present invention, the electrodeposition plating solution is composed of water, nickel nitrate hexahydrate, ferrous sulfate heptahydrate, cobalt nitrate hexahydrate, sodium citrate dihydrate, boric acid, and sodium nitrate. When the pH of the electrodeposition plating solution is 3.5, the concentrations of nickel nitrate hexahydrate, ferrous sulfate heptahydrate, cobalt nitrate hexahydrate, sodium citrate dihydrate, boric acid, and sodium nitrate are 0.15 M, 0.15 M, and 0.1 M, respectively.

[0037] Embodiments of the present invention also provide a copper-framework composite catalytic material prepared according to the above method.

[0038] Embodiments of the present invention also provide an application of the above-mentioned copper-framework composite catalytic material in oxygen evolution through water electrolysis.

[0039] This invention successfully fabricated a copper-framework catalytic electrode by in-situ constructing a copper nanoframework on a copper foam substrate and electrodepositing a catalytically active layer. The dynamic evolution of the active phase during the oxygen evolution process in water electrolysis was investigated using advanced in-situ characterization methods and theoretical calculations. Furthermore, the electrode's service behavior was studied by simulating an industrial operating environment, and the large-area fabrication process of the copper-framework catalytic electrode was further explored, providing theoretical and technical support for the design of high-performance water electrolysis catalytic electrodes. Details are as follows: First, a series of redox steps, including chemical oxidation, high-temperature calcination, and hydrogen reduction, are proposed to construct a multi-level copper nanoframework on the surface of copper foam in situ. A highly catalytically active nickel-iron-cobalt ternary alloy catalyst layer will then be loaded using constant current electrodeposition technology. By adjusting the current density and electrodeposition time, the effects of current density and electrodeposition time on the electrode micro / nanostructure and catalytic performance will be systematically investigated. The structure-activity relationship between micro / nanostructure and catalytic performance will be clarified, establishing a research approach of "process parameters – micro / nanostructure – catalytic performance," and ultimately determining the optimal preparation process conditions.

[0040] Secondly, by comprehensively utilizing a variety of advanced characterization methods such as in-situ Raman spectroscopy, in-situ infrared spectroscopy, and in-situ X-ray diffraction, the active phase and intermediate state of the oxygen evolution reaction process of the copper framework catalytic electrode are tracked in real time. This allows for a deeper understanding of the influence of elemental doping on the dynamic evolution of the active phase and the reaction pathway, revealing the catalytic mechanism and key optimization steps of the copper framework catalytic electrode. Furthermore, by combining first-principles calculations, the thermodynamic regulation mechanism of elemental doping on the reaction is explored, elucidating the microscopic mechanism of catalytic performance enhancement and providing theoretical guidance for the rational design of high-performance electrodes.

[0041] Finally, based on previous research on small-area electrodes, we plan to explore the large-scale preparation process of large-area copper-framework / ternary alloy catalytic electrodes. We will build a simulated industrial alkaline electrolyzer testing system (30 wt.% KOH, 60℃) with constant temperature control, electrolyte circulation, and gas-liquid separation functions to systematically evaluate the oxygen evolution activity, energy consumption characteristics, and long-term service stability of large-area electrodes at industrial-grade current densities. We will also investigate the structural evolution and failure mechanism of the electrodes under harsh operating conditions, providing technical support and theoretical basis for the practical industrial application of copper-framework non-precious metal catalytic electrodes.

[0042] In summary, this invention prepares a high-performance copper-framework catalytic electrode through an in-situ construction strategy, revealing the structure-activity relationship between the micro / nano structure and catalytic performance of the copper-framework catalytic electrode under different synthesis conditions. Furthermore, it explores the dynamic reconstruction and reaction pathways of this catalytic electrode through various in-situ characterization techniques and theoretical calculations, and examines the electrode's service behavior under harsh operating conditions. This invention provides a theoretical basis for the design of high-performance water electrolysis catalysts and has positive significance for promoting the large-scale development of the green hydrogen industry.

[0043] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0044] All raw materials used in the embodiments of the present invention were purchased commercially. For example, copper foam (CF) and nickel foam (NF) were purchased from Kunshan Jiayisheng Electronics Co., Ltd., and both copper foam and nickel foam had a PPI of 85 and an areal density of 650.

[0045] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0046] The technical solution of the present invention will be further illustrated by the following embodiments.

[0047] Example 1 A method for preparing a copper-framework composite catalytic material, comprising the following steps: (1) In-situ construction of copper nanoframework like Figure 1As shown, firstly, 2×5 cm pieces of copper foam were cut and ultrasonically cleaned sequentially with 30% dilute hydrochloric acid and acetone for 15 min, followed by ultrasonic cleaning with deionized water for 10 min to remove the oxide layer and organic residues on the surface of the copper foam. After cleaning, the copper foam was dried with an argon gas gun to remove any remaining moisture. Subsequently, copper hydroxide nanowires were grown on the surface of the copper foam through chemical oxidation. Specifically, the cleaned copper foam was immersed in 80 mL of a chemical oxidation solution for alkaline etching growth. The chemical oxidation solution consisted of water, ammonium persulfate, and sodium hydroxide, with the ammonium persulfate concentration being 0.125 M and the sodium hydroxide concentration being 2.5 M. The growth was carried out at a constant temperature for 20 min. The specific chemical oxidation reaction is as follows: Cu + 4NaOH + (NH4)2S2O8 → Cu(OH)2 + 2Na2SO4 + 2NH3 + 2H2O. The blue sample obtained in the previous step was placed in a tube furnace and calcined in air at a temperature of 180℃ for 60 min to convert copper hydroxide nanowires into copper oxide nanowires. After the reaction was completed and the furnace cooled naturally to room temperature, the black sample obtained was placed in a tube furnace for hydrogen reduction. The calcination temperature was set to 285℃ and the holding time was 150 min. The flow rates of argon and hydrogen were set to 180 sccm and 20 sccm, respectively. After the program ended, the experiment was terminated under an argon atmosphere with a flow rate of 100 sccm until the temperature dropped to room temperature. During the reduction process, CuO nanowires were reduced to Cu nanoframeworks, denoted as Cu NW.

[0048] (2) Active layer loading A 2×5 cm sample of the red sample (i.e., Cu nanoframework) after hydrogen reduction in the previous step was cut, and a nickel-iron-cobalt ternary alloy catalyst layer was loaded using a constant current electrodeposition process. First, the electrodeposition bath (pH=3.5) was prepared by weighing out the following components: water, nickel nitrate hexahydrate, ferrous sulfate heptahydrate, cobalt nitrate hexahydrate, sodium citrate dihydrate, boric acid, and sodium nitrate. The concentrations of nickel nitrate hexahydrate, ferrous sulfate heptahydrate, cobalt nitrate hexahydrate, and sodium citrate dihydrate were 0.15 M, acting as a complexing agent; boric acid was 0.15 M, which inhibits metal ion hydrolysis; and sodium nitrate was 0.1 M, acting as a pH buffer to ensure a stable electrodeposition process and a uniform and dense coating. Then, the hydrogen-reduced red sample was placed in the electrodeposition bath for dual-electrode constant current electrodeposition. Nickel foam was used as the counter electrode, and the constant current density was -20 mA·cm⁻¹. -2 Electrodeposition was performed for 20 min to load a Ni-Fe-Co ternary alloy layer onto the Cu nanoframework, resulting in a copper-framework composite catalytic material, which is a copper-framework / ternary alloy composite catalytic material (also known as a copper-framework / ternary alloy catalytic electrode), denoted as Cu NW@NiFeCo.

[0049] Comparative Example 1: Preparation of Cu NW@NiFe The Cu NW@NiFe was prepared using the method described in Example 1, except for the active layer loading step. The electrodeposition bath consisted of water, nickel nitrate hexahydrate, ferrous sulfate heptahydrate, sodium citrate dihydrate, boric acid, and sodium nitrate. The concentrations of nickel nitrate hexahydrate, ferrous sulfate heptahydrate, and sodium citrate dihydrate were 0.15 M and 0.015 M respectively, acting as a complexing agent. Boric acid was 0.15 M, which inhibits metal ion hydrolysis. Sodium nitrate was 0.1–0.3 M, acting as a pH buffer to ensure a stable electrodeposition process and a uniform, dense coating. The hydrogen-reduced red sample was then placed in the electrodeposition bath for dual-electrode constant current electrodeposition. The counter electrode was made of nickel foam, and the constant current density was -20 mA·cm⁻¹. -2 Electrodeposition was performed for 20 min to load a Ni-Fe ternary alloy layer onto the Cu nanoframework, resulting in a copper-framework composite catalytic material, which is a copper-framework / binary alloy composite catalytic material (also known as a copper-framework / ternary alloy catalytic electrode), denoted as Cu NW@NiFe.

[0050] Comparative Example 2: Preparation of Cu NW@Ni The Cu NW@Ni was prepared using the method described in Example 1, except for the active layer loading step. The electrodeposition bath consisted of water, nickel nitrate hexahydrate, sodium citrate dihydrate, boric acid, and sodium nitrate. The concentration of nickel nitrate hexahydrate was 0.15 M; the concentration of sodium citrate dihydrate was 0.015 M, which acted as a complexing agent; the concentration of boric acid was 0.15 M, which inhibited the hydrolysis of metal ions; and the concentration of sodium nitrate was 0.1–0.3 M, which acted as a pH buffer to ensure the stability of the electrodeposition process and the uniformity and density of the coating. The hydrogen-reduced red sample was then placed in the electrodeposition bath for dual-electrode constant current electrodeposition. The counter electrode was made of nickel foam, and the constant current density was -20 mA·cm⁻¹. -2 Electrodeposition was performed for 20 minutes to load Ni unit alloy layers onto the Cu nanoframework, resulting in a copper-framework composite catalytic material, which is a copper-framework / unit alloy composite catalytic material (also known as a copper-framework / ternary alloy catalytic electrode), denoted as Cu NW@Ni.

[0051] The following discussion will cover the regulatory mechanisms and effects of nickel, nickel-iron, and nickel-iron-cobalt systems on the microstructure, active phase evolution, and alkaline oxygen evolution catalytic performance of copper-framework catalytic electrodes: To reveal the in-situ construction mechanism of the copper framework catalytic electrode, the morphology of each stage of the copper framework catalytic electrode was characterized by optical microscopy and scanning electron microscopy (SEM), and the dynamic evolution of the copper framework / ternary alloy composite catalytic material was systematically studied. Optical and SEM images of each stage of the copper nanowire framework construction process are shown below. Figure 2 As shown, the original copper foam exhibits a loose, porous 3D network structure. After the first step of chemical oxidation, the overall color changes from bright yellow to blue, and a uniform copper hydroxide nanoarray grows on the surface, consolidating the initial framework template for subsequent material growth. The subsequent calcination process keeps the nanowire array intact but its distribution becomes somewhat disordered, resulting in a predominantly black sample. Hydrogen reduction successfully prepares a copper nanoframework, restoring the sample to its original red color, providing a framework substrate with both high specific surface area and excellent electron transport capabilities for the subsequent loading of the highly active alloy layer. After high-temperature calcination, the overall structure of the nanowire array remains intact, but due to high-temperature oxidation and structural reorganization, its distribution changes from regular to relatively disordered, and the overall color of the sample turns black, completing the phase transformation from copper hydroxide to copper oxide. Hydrogen reduction successfully constructs a three-dimensional copper nanoframework, restoring the sample to its intrinsic copper red color. The nanowire arrays are interconnected and interwoven, forming a multi-level network framework substrate with high specific surface area, excellent conductivity, and good structural stability, providing ideal carrier conditions for the uniform loading, tight bonding, and efficient electron transport of the subsequent nickel-iron-cobalt ternary alloy catalyst layer.

[0052] SEM images of copper-based composite catalysts at different magnifications are as follows: Figure 3 As shown, this invention successfully constructs a multi-level catalytic electrode material with copper nanowires as the core and sheet-like nanosheet structures as the shell. The copper nanoarray constructs a highly conductive three-dimensional framework, with uniformly grown sheet-like secondary structures interwoven on its surface, forming a petal-like open morphology. This multi-level structure achieves a synergistic design between a conductive substrate and a highly active surface layer: on the one hand, the nanowire framework ensures rapid charge conduction; on the other hand, the high specific surface area of ​​the sheet-like structure exposes abundant active sites and optimizes mass transfer, thereby endowing the electrode with excellent catalytic performance.

[0053] To determine the phase composition and alloying degree of the copper-framework composite catalytic material, X-ray diffraction (XRD) was used to analyze and characterize the sample. Figure 4Figure (a) shows the diffraction patterns of different electrode materials. The strong diffraction peaks at 43.3°, 50.5°, and 74.2° are attributed to the (111), (200), and (220) crystal planes of face-centered cubic Cu, indicating good crystallinity of the copper framework substrate. However, it should be noted that the diffraction signal intensity of the copper framework substrate is significantly higher than that of the alloy catalyst layer, causing some interference to the identification of the characteristic diffraction peaks of the nickel-iron-cobalt ternary alloy layer. This makes it difficult to accurately identify the weak characteristic diffraction signals of the alloy layer, posing a challenge to quantitative phase analysis and accurate assessment of the degree of alloying.

[0054] To accurately identify the phase structure of the load layer and avoid interference from the strong diffraction signal of the copper substrate, this invention uses carbon paper as a substrate and prepares a nickel-iron-cobalt ternary alloy control group sample (denoted as CP@NiFeCo) under the same electrodeposition conditions as in Example 1. Figure 4 As shown in (b), the diffraction peaks of the control sample generally exhibit a face-centered cubic structure, which is basically consistent with the position of the standard diffraction peaks of metallic nickel (JCPDS No. 04-0850), indicating that the alloy mainly consists of nickel as the crystalline phase. However, all diffraction peaks shift towards lower angles. According to Bragg's equation... The decrease in the diffraction angle directly reflects the increase in the lattice constant.

[0055] This lattice expansion phenomenon originates from the substitution of some Ni (1.24 Å) atomic sites by Fe (1.24 Å) and Co (1.25 Å), which have larger atomic radii, forming a substitutional solid solution alloy, rather than a simple mixture of elements or oxides. The phase identification results not only confirm that this invention successfully prepared a single-phase homogeneous nickel-iron-cobalt ternary alloy via electrodeposition, but also provide crucial experimental evidence for subsequent investigations into the regulation mechanism of alloy composition on catalytic performance and clarifying the structure of the active phase. Furthermore, it further corroborates that the copper-supported ternary alloy catalyst layer possesses excellent crystal integrity and structural stability.

[0056] To avoid interference from transition metal elements in the electron microscopy characterization of the material, the microstructure of the copper framework composite catalytic material was characterized using a non-magnetic transmission electron microscope (TEM). The results are as follows: Figure 5 As shown, Figure 5 Image (a) clearly reveals the core-shell structure of the electrode, with a high-contrast copper nanoarray forming a highly conductive core, uniformly coated with a shallow-contrast nickel-iron-cobalt alloy layer. (High-resolution TEM image) Figure 5Images (b) and (c) show that the lattice spacing of the alloy layer is 0.206 nm, a slight expansion compared to the theoretical value (0.203 nm) for the face-centered cubic Ni(111) crystal plane. This lattice expansion originates from the substitution of some nickel sites by iron and cobalt atoms with larger atomic radii, leading to lattice distortion. This directly confirms the successful formation of the ternary substitutional solid solution alloy phase at the microscopic level. Selected area electron diffraction (SAED) pattern ( Figure 5 (d) shows that the diffraction rings exhibit uneven brightness and local discontinuities, further confirming that the alloy layer is a nano-polycrystalline structure.

[0057] Furthermore, the elemental distribution map from energy-dispersive spectroscopy (EDS) ( Figure 5 Figures (e) to (i) show that nickel, iron, and cobalt elements are uniformly distributed at the atomic level in different regions on the surface of the copper framework. The copper nanoframework serves as the core, and the nickel-iron-cobalt alloy grows uniformly on the copper nanoframework in a sheet-like morphology, achieving a uniform atomic-level distribution throughout the entire domain. The above TEM observations and the systematic shift of diffraction peaks in the XRD analysis corroborate each other, providing bidirectional evidence from the macroscopic phase to the microscopic crystal structure, fully demonstrating that this invention successfully constructed a copper-based supported ternary alloy catalytic system with a complete structure and uniform elemental distribution.

[0058] To further elucidate the surface chemical states and inter-element electronic interactions of copper-framework composite catalytic materials, X-ray photoelectron spectroscopy (XPS) was used to systematically analyze copper-framework / ternary alloy catalytic material samples. Figure 6 The XPS full spectrum in (a) confirms the coexistence of four elements, Ni, Fe, Co and Cu, on the electrode surface. Figure 6 As shown in (b), the Cu 2p spectrum only shows the metallic state of Cu. 0 Characteristic double peaks (932.6 eV and 952.4 eV), and no Cu. 2+ The satellite peaks indicate that the copper framework maintains a stable metallic state in the electrochemical environment, providing an efficient pathway for electron transport and serving as a highly conductive framework to provide an efficient conduction pathway for interfacial charge transport.

[0059] Figure 6 Images (c) through (e) are high-resolution spectra of Ni 2p, Fe 2p, and Co 2p, respectively, all exhibiting significant zero-valence characteristic peaks (Ni). 0 2p 3 / 2 852.8 eV; Fe 0 2p 3 / 2 707.1 eV; Co 0 2p 3 / 2The XPS analysis (778.4 eV) confirmed that Ni, Fe, and Co exist in metallic form. Notably, the coexistence of the three metals in their zero-valence states, along with a slight shift in binding energy compared to the standard values ​​for pure metals, indicates significant interfacial electron transfer and interaction among Ni, Fe, and Co. This is highly consistent with the substitutional solid solution alloy phase formation characteristics confirmed by XRD and TEM. In summary, the XPS analysis results show that the prepared electrode surface is dominated by metallic Ni, Fe, Co, and Cu, and the electronic synergistic effect among these elements lays the electronic structural foundation for improved catalytic performance.

[0060] In addition, combined Figure 6 Cu 2p spectrum in (b) does not show Cu 2+ Satellite peaks and Cu 0 The stable positions of the characteristic peaks indicate that the copper framework maintains a metallic state during electrodeposition and subsequent processing, providing an efficient channel for electron transport. This coexistence of multiple metal zero-valent states and interfacial electronic reconstruction not only helps reduce charge transfer impedance but also optimizes the adsorption energy of oxygen-containing intermediates (such as *OH, *OOH, etc.) at active sites, thus laying the electronic structural foundation for enhancing the intrinsic activity of the oxygen evolution reaction (OER).

[0061] To reveal the electronic interaction between the copper framework and the nickel-iron-cobalt ternary alloy catalyst layer, the work function of the sample was systematically characterized using ultraviolet photoelectron spectroscopy (UPS, He I light source, hν = 21.22 eV). Figure 7 As shown in (a) to (c), the secondary electron cutoff edges of the copper nanoframework substrate, the nickel-iron-cobalt ternary alloy catalytic coating (hydrophilic carbon paper substrate), and the copper framework / ternary alloy catalytic material are located at 16.22 eV, 16.11 eV, and 16.35 eV, respectively. Since the Fermi edge of the metal sample is located at the binding energy zero, the work function is calculated using the formula... The work functions of the three structures were found to be 5.00 eV, 5.11 eV, and 4.87 eV, respectively, confirming the successful construction of the nano-core-shell heterostructure.

[0062] In band structure analysis, the light absorption cutoff edge of the copper nanoframework-supported nickel-iron-cobalt ternary alloy catalytic layer composite electrode (i.e., the copper framework composite catalytic material in Example 1) shifted significantly to the positive direction, with an increase of up to 0.24 eV compared to the pure nickel-iron-cobalt ternary alloy layer (i.e., the nickel-iron-cobalt ternary alloy catalytic coating (hydrophilic carbon paper substrate)). This significant shift in the absorption cutoff edge fully confirms that after the copper nanoframework and the nickel-iron-cobalt ternary alloy active layer form a core-shell heterostructure, spontaneous electron migration occurs from the copper nanoframework to the nickel-iron-cobalt ternary alloy layer within their interface. This design effectively regulates and reduces the surface barrier height at the heterostructure interface. This band structure regulation and interfacial charge transfer behavior, along with the characteristic element binding energy shift observed by XPS, the decrease in charge transfer resistance in subsequent electrochemical tests, and the in-situ infrared spectroscopy characterization of intermediate adsorption behavior, form a multi-dimensional mutual corroboration, jointly confirming the significant interfacial electronic interaction and multi-component synergistic enhancement mechanism between the copper nanoframework and the nickel-iron-cobalt ternary alloy active layer.

[0063] To achieve controllable preparation of the catalytic alloy layer on the surface of a copper framework / ternary alloy catalytic electrode, a constant current electrodeposition process was employed. The pH value of the electrodeposition bath was controlled within the range of 3.0–4.0, a condition that inhibits Ni… 2+ Fe 2+ Co 2+ The hydrolysis of three metal ions generates hydroxide precipitates, ensuring the catalytic activity of each metal element. Compared to the constant potential mode, the constant current mode provides a more stable deposition rate, which is beneficial for maintaining the consistent deposition ratio of each component in the multi-element alloy during the preparation process, thereby obtaining a coating with uniform composition and stable structure. Therefore, this invention systematically studies the effects of two key parameters, deposition current density and deposition time, on the microstructure and catalytic performance of the electrode body. By optimizing the spatial structure of the material itself, the structure-activity relationship between the micro-nano structure of the copper framework catalytic electrode material and its catalytic performance was explored, and the optimal electrodeposition process conditions were determined.

[0064] Building upon the in-situ controllable construction of a three-dimensional copper nanoframework on a copper foam substrate, an electrochemical deposition process was further employed to uniformly load a nickel-iron-cobalt ternary alloy active catalytic layer onto the framework surface. Following the method described in Example 1, a -20 mA cm⁻¹ catalyst was selected. -2 Using a constant current density as the constant process parameter for electrodeposition, and by setting and adjusting three different electrodeposition time gradients of 5 min, 10 min, and 30 min, the effects of different electrodeposition parameters on the micro / nano structure and oxygen evolution performance of the copper framework catalytic electrode were systematically investigated and compared. The morphological evolution of the copper framework composite catalytic material under different electrodeposition times was characterized using scanning electron microscopy (SEM), and the results are as follows: Figure 8As shown in the figure, the microstructure characterization results of the copper-framework composite catalytic materials constructed under four different electrodeposition time gradients, including Example 1, are presented. With the extension of electrodeposition time, the loading of the alloy catalytic layer on the surface of the copper nanoframework increases, and the coating thickness continuously increases. In the initial stage of electrodeposition (5-10 min), the nickel-iron-cobalt ternary alloy layer uniformly coats the surface of the copper nanoframework, with the nanowire diameter remaining at 100-200 nm. When the electrodeposition time continues to increase to 20 min, the coating thickness increases significantly, and the nanowire diameter increases to 300-500 nm. However, when the electrodeposition time continues to 30 min, the nanoframework is completely covered, forming a large-area coating, and phenomena such as cracking and localized peeling occur. This is because the excessively thick coating generates large internal stress during the electrodeposition process, coupled with the uneven current distribution caused by the difference in surface curvature of the framework, jointly leading to the instability of the catalytic electrode structure. Therefore, the appropriate electrodeposition time is determined to be 20 min to obtain a complete and uniform alloy coating.

[0065] Figure 9 Elemental composition analysis of copper-based composite catalysts was performed using energy dispersive spectroscopy (EDS) at four electrodeposition times. EDS analysis results showed that the proportions of nickel, iron, and cobalt gradually increased with increasing electrodeposition time, confirming an increase in catalyst loading, consistent with the morphological evolution trend observed by SEM.

[0066] Subsequently, the oxygen evolution performance of the copper-based composite catalyst in water electrolysis was tested using a three-electrode system at four different electrodeposition times. The counter electrode was a carbon rod, the reference electrode was a silver chloride reference electrode, and the electrolyte was 1 M potassium hydroxide. Figure 10 As shown, with the extension of electrodeposition time, the oxygen evolution performance of the copper framework catalytic electrode exhibits a trend of first significantly increasing and then gradually decreasing. With the extension of electrodeposition time, the oxygen evolution performance of samples at 5 min, 10 min, 20 min, and 30 min at 10 mA·cm⁻¹... -2 The overpotentials at current densities were 243 mV, 240 mV, 203 mV, and 226 mV, respectively, at 100 mA·cm⁻¹. -2 The overpotentials at the current densities were 301 mV, 291 mV, 245 mV, and 270 mV, respectively; the Tafel slope was 34.78 mV·dec. -1 27.91 mV·dec -1 20.04 mV·dec -1 and 31.29 mV·dec -1 Meanwhile, through impedance comparison diagrams, the charge transport impedances under the four time parameters are 0.68 Ω, 0.58 Ω, 0.41 Ω and 0.42 Ω, respectively.

[0067] To further investigate the effect of electrodeposition time on the interfacial properties of copper-based composite catalytic materials, this invention employs cyclic voltammetry at different scan rates to measure the electrochemically active specific surface area (ECSA) of materials at four electrodeposition times, and then calculates the double-layer capacitance (C0). dl Quantification is performed. For example... Figure 11 As shown, the C values ​​for samples at 5 min, 10 min, 20 min, and 30 min are... dl They are 16.56 mF·cm -2 13.65 mF·cm -2 13.93 mF·cm -2 and 13.18 mF·cm -2 .

[0068] With increasing electrodeposition time, the C content of the deposited sample increased compared to the undeposited copper nanoframework electrode. dl Slightly decreased, but still remained at a high level. Combined with SEM morphology analysis, in the initial stage of electrodeposition (5-10 min), the alloy layer uniformly coated the copper nanoframework, fully exposing the active sites; at 20 min, the coating thickened, but the copper nanoframework structure remained intact, and the electrochemical active area decreased slightly; when the deposition time was extended to 30 min, the excessively thick coating completely covered the copper nanoframework, causing some active sites to be buried. Simultaneously, coating cracking exacerbated structural instability, ultimately leading to C... dl The effect was reduced. Therefore, an electrodeposition time of 20 min was confirmed as the optimal process condition for optimizing the interfacial properties of the copper framework catalytic electrode material and improving catalytic performance.

[0069] The combined analysis of multiple electrocatalytic performance parameters, including overpotential, Tafel slope, charge transfer impedance, and electrochemical active area, shows that when the electrodeposition time is 20 min, the prepared copper-framework composite catalytic electrode constructs a rich, multi-level micro / nano structure, effectively increasing the electrode's electrochemical active area, exposing abundant catalytic active sites, and exhibiting the lowest oxygen evolution overpotential, the smallest Tafel slope, and the optimal interfacial charge transport capability, demonstrating the most superior intrinsic oxygen evolution catalytic activity and reaction kinetics. In conclusion, the copper-framework catalytic electrode exhibits optimal catalytic performance when the electrodeposition time is 20 min.

[0070] The previous work systematically explored the regulatory mechanisms of electrodeposition time parameters on the microstructure and catalytic performance of copper-based composite catalysts in water electrolysis and oxygen evolution, clarifying the intrinsic structure-activity relationship between electrodeposition time and the micro / nano morphology and catalytic performance of the materials, providing an important basis for subsequent process optimization. Building upon this previous research, this study further delves into the impact of electrodeposition current density as the core variable, focusing on revealing the influence mechanisms of different deposition current densities on electrode microstructure evolution, alloy layer growth, active site distribution, and electrochemical kinetics, elucidating the intrinsic relationship between structure and performance. Through comprehensive characterization and analysis of the electrode surface micro / nano morphology and various electrochemical performance indicators, the optimal electrodeposition process parameters were finally screened and determined.

[0071] Following the method in Example 1, a deposition time of 20 min was selected as the constant process parameter for electrodeposition, and the setting was adjusted by -10 mA·cm. -2 -30 mA·cm -2 -40 mA·cm -2 and -50 mA·cm -2 Four different current density gradients were used to systematically investigate and compare the evolution of the microstructure of copper-framework composite catalytic materials and the differences in their oxygen evolution catalytic performance under five different current densities, including Example 1, to reveal the intrinsic structure-activity relationship among deposition current density, microstructure, and catalytic performance.

[0072] The morphological evolution of copper framework / ternary alloy catalysts under different electrodeposition current densities was characterized using scanning electron microscopy (SEM), and the results are as follows: Figure 12 As shown. At -20 mA·cm -2 Under certain current density conditions, a nickel-iron-cobalt alloy layer uniformly coats the surface of a three-dimensional copper nanoframework, preserving the original hierarchical micro / nano structure of the copper framework while achieving uniform loading of the catalytically active components. When the current density is increased to -30 and -40 mA·cm⁻¹, the effect is further enhanced. -2 At this point, the particle size of the alloy catalyst layer increases significantly, and the coating thickness increases markedly. The original three-dimensional structure of the copper nanoframework is gradually covered by the alloy layer, and the original advantages of the copper nanoframework are weakened. When the current density further increases to -50 mA·cm -2 At this point, the nanowire framework is completely covered by the alloy layer, the original morphology disappears, and local agglomeration occurs. This morphological evolution is mainly attributed to the rapid accumulation effect of active material under excessively high current density, resulting in an excessively fast deposition rate, which is not conducive to the fine control of the microstructure of the copper framework catalytic electrode.

[0073] Excessively high deposition current density significantly accelerates the electroreduction process of metal ions in the electrolyte, causing rapid accumulation and disordered growth of active alloy components on the surface of the copper foam substrate. This makes it difficult to form uniform nucleation and orderly grain growth patterns, hindering the precise control and construction of the copper framework catalytic electrode micro / nano structure. Therefore, selecting an appropriate deposition current density is a crucial prerequisite for ensuring uniform coating of the catalytic layer and complete preservation of the multi-level structural advantages of the copper nanoframework. Thus, a moderate current density (-20 mA·cm⁻¹) is essential. -2 It can produce copper framework / ternary alloy catalytic electrodes with regular micro-nano morphology and uniform loading of active components, and has the optimal deposition current density.

[0074] Figure 13 The following are the elemental composition analysis results of the copper-based composite catalyst material under five different deposition current densities using energy dispersive spectroscopy (EDS). The analysis results confirm that the relative content of nickel, iron, and cobalt on the electrode surface gradually increases with increasing electrodeposition current density. This phenomenon directly demonstrates that the loading of the nickel-iron-cobalt ternary alloy catalyst layer on the copper-based substrate continuously increases with increasing current density. The variation law of elemental content perfectly matches the morphological evolution characteristics of gradual coating thickening and continuous accumulation of active components observed in SEM characterization, further verifying from a quantitative perspective that deposition current density can effectively regulate the loading degree of catalytic components and the microstructure characteristics of the electrode.

[0075] The oxygen evolution performance of copper-framework / ternary alloy catalysts in water electrolysis under different deposition current densities was tested using a three-electrode system. The counter electrode was a carbon rod, the reference electrode was a silver chloride reference electrode, and the electrolyte was 1 M potassium hydroxide. Figure 14 As shown, with the increase of deposition current density, the catalytic performance of water electrolysis first increases and then decreases.

[0076] Among them, -10 mA·cm -2 -20 mA·cm -2 -30 mA·cm -2 -40 mA·cm -2 and -50 mA·cm -2 Five samples with different deposition current densities at 10 mA·cm -2 The overpotentials were 225 mV, 202 mV, 216 mV, 233 mV and 242 mV, at 100 mA·cm⁻¹. -2 The overpotentials were 273 mV, 249 mV, 263 mV, 272 mV, and 301 mV; the Tafel slope was 25.68 mV·dec. -1 20.04 mV·dec -1 23.57 mV·dec -120.27 mV·dec -1 and 29.33 mV·dec -1 Meanwhile, through impedance comparison diagrams, the charge transport impedances under the five deposition current density parameters are 0.493 Ω, 0.4 Ω, 0.451 Ω, 0.465 Ω, and 0.62 Ω, respectively.

[0077] In summary, when the deposition current density is -20 mA·cm -2 At this time, the prepared copper-framework composite catalyst exhibits the lowest overpotential, the smallest Tafel slope, and the lowest interfacial charge transport impedance, resulting in superior reaction kinetics and demonstrating optimal intrinsic oxygen evolution catalytic performance. Therefore, -20 mA cm⁻¹ -2 The optimal electrodeposition current density for the copper-framework composite catalytic material in this invention is achieved under this condition, which enables uniform loading of active components, complete preservation of microstructure, and optimal catalytic performance for oxygen evolution in water electrolysis. This provides key process parameters to support subsequent large-scale preparation and industrial application.

[0078] To further investigate the effect of deposition current density on the interface properties of copper framework / ternary alloy catalytic electrodes, cyclic voltammetry at different scan rates was used to measure the electrochemically active specific surface area (ECSA) of the materials under different electrodeposition current densities, and then the double-layer capacitance (C0) was calculated. dl Quantification is performed. For example... Figure 15 As shown, -10 mA·cm -2 -20 mA·cm -2 -30 mA·cm -2 -40 mA·cm -2 and -50 mA·cm -2 Five samples with different deposition current densities C dl They are 18.57 mF cm·cm -2 12.63 mF·cm -2 14.44 mF·cm -2 16.4 mF·cm -2 and 8.43 mF·cm -2 .

[0079] Based on previous SEM morphology analysis, at -10 mA·cm -2 At a deposition current density of [value missing], the deposition layer is thin but uniform, and the catalytic active sites are fully exposed, therefore C [value missing]. dl The value was highest; it increased to -20 mA·cm. -2 At this time, the coating thickness is moderate, the morphology is regular, the active area decreases slightly, but the structural stability of the copper framework catalytic electrode is improved; -30 to -40 mA·cm -2 At that time, the increased thickness of the deposited coating leads to an increase in the surface roughness of the catalytic electrode, Cdl The values ​​have rebounded, but excessively thick coatings may introduce internal stress into the material, affecting long-term stability; -50 mA·cm -2 At that time, the copper nanoframework was completely covered, while some active sites were buried due to low deposition current density, leading to structural instability and C dl A sudden drop.

[0080] In summary, -20 mA·cm -2 The deposition current density was confirmed to be the optimal process condition for optimizing the interfacial properties of the copper framework catalytic electrode material and improving its catalytic performance. This process parameter can effectively control the micro / nano structure and catalytic performance of the copper framework catalytic electrode, achieving overall optimization and synergistic enhancement of the electrode's oxygen evolution catalytic capability by balancing the electrochemical active area and catalytic activity.

[0081] This invention prepares a copper-based composite catalytic material (copper framework / ternary alloy catalytic electrode) by in-situ constructing a copper nanoframework on the surface of a copper catalytic electrode and loading it with nickel, iron, and cobalt using electrodeposition technology. The deposition time and deposition current density, two key process parameters, were systematically controlled to investigate their effects on the micro / nano structure and catalytic performance of the electrode surface. The main conclusions are as follows: (1) A uniformly grown copper nanowire array was successfully constructed on the surface of copper foam through a series of redox steps; based on this, a nickel-iron-cobalt ternary alloy catalytic layer was loaded using a constant current electrodeposition method. The micro-nano structure and catalytic performance of the material under different electrodeposition process parameters were systematically studied, and the optimal electrodeposition parameters were determined to be -20 mA·cm⁻¹. -2 The optimal deposition process parameters for maintaining the morphological advantages and catalytic activity of the copper framework catalytic electrode are 20 min.

[0082] (2) The microstructure and phase composition of the electrode were systematically characterized by SEM, TEM, and XRD. The results showed that the catalytic electrode maintained a complete three-dimensional copper nanoframework structure, with a nickel-iron-cobalt alloy layer uniformly coating the surface of the copper nanowires, forming a regular core-shell heterostructure. XPS and UPS studies verified that this unique structural design not only promoted the electronic reconstruction of the interface between the substrate and the catalyst layer, but also facilitated charge transport and subsequent catalytic reactions such as the adsorption of oxygen evolution intermediates.

[0083] (3) Electrochemical test results show that the prepared copper framework / ternary alloy catalytic electrode exhibits excellent oxygen evolution performance in 1.0 M KOH solution. At 10 mA·cm⁻¹ -2 and 100 mA·cm -2 At the given current density, the oxygen evolution overpotentials are only 202 mV and 249 mV, and the Tafel slope is 20.04 mV·dec. -1 The charge transport impedance is 0.4 Ω, and the interface capacitance is 13.93 mF·cm.-2 .

[0084] As mentioned earlier, ultraviolet photoelectron spectroscopy (UPS) tests showed that the work function of the copper framework / ternary alloy catalytic electrode (4.87 eV) was lower than that of the copper framework catalytic electrode before electrodeposition (5.00 eV) and the nickel-iron-cobalt catalytic layer (5.11 eV). This directly confirms that strong electronic interactions formed between the copper framework substrate and the nickel-iron-cobalt alloy layer, electronic rearrangement occurred at the contact interface, and the interface barrier was significantly reduced, effectively lowering the charge transport interface barrier. Figure 16 As shown in (b), this conclusion is further supported by resistivity test results. After loading the nickel-iron-cobalt ternary alloy catalyst layer, the resistivity of the copper framework catalytic electrode decreased from 1.876 × 10⁻⁶. -6 Ωm becomes 1.8762 × 10 -6 The resistivity of the nickel foam electrode and the nickel-iron-cobalt alloy electrode with a resistivity of Ωm is much lower than that of the nickel foam electrode and the nickel foam electrodeposited nickel-iron-cobalt alloy electrode, which fully demonstrates that the interfacial electron rearrangement effectively improves the overall conductivity of the electrode and accelerates the interfacial charge transport efficiency.

[0085] Therefore, by electrodepositing a nickel-iron-cobalt ternary alloy layer, electronic reconstruction occurs between the copper framework substrate and the alloy catalyst layer, the interfacial electron transport barrier is reduced, and the conductivity is further optimized. In addition, it induces the shift of the catalyst d-band center, precisely regulates the electronic structure of the active site, and strengthens the interaction between the catalyst and the oxygen evolution reaction intermediate. From the aspects of electronic structure regulation and intermediate adsorption activity, the oxygen evolution catalytic activity and reaction kinetics performance of the copper framework electrode are significantly improved.

[0086] Composite catalytic materials based on copper foam (CF@NiFeCo) and nickel foam (NF@NiFeCo) were prepared according to the method in Example 1. By comparing the electrochemical active areas of the original copper foam, the copper catalytic electrode with a copper nanoframework, the copper-framework catalytic electrode supported on a nickel-iron-cobalt alloy catalytic layer, the nickel foam electrode, and the commercial iridium dioxide electrode, the interfacial characteristics and catalytic potential of different electrodes were comprehensively evaluated from the perspective of the correlation between interfacial structure and catalytic activity. The results showed that in-situ construction of the copper nanoframework increased the electrochemical active area of ​​the copper foam electrode from the initial 125.75 cm². 2 Increased to 398.75 cm 2 After subsequent electrodeposition of a nickel-iron-cobalt ternary alloy catalyst layer, the composite electrode still retains the interfacial structural advantages of the copper nanoframework, and its electrochemical active area remains at 348.25 cm². 2 The test data fully demonstrates that the multi-level structural advantages of the copper nanoframework are effectively preserved, and the alloy layer loading does not disrupt the open mass transfer channels of the copper substrate, providing sufficient and easily accessible active sites for the oxygen evolution reaction and ensuring excellent interfacial reaction efficiency.

[0087] Furthermore, this electrode exhibits significant advantages in multiple performance indicators, including oxygen evolution overpotential, Tafel slope, and charge transfer impedance, demonstrating excellent electrocatalytic activity and reaction kinetics. Material performance was tested using a three-electrode system, and solution impedance compensation was performed during data processing. Figure 17 It can be seen that at 10 and 100 mA·cm -2 At current densities, the overpotentials of the copper framework / ternary alloy catalytic electrode are only 203 mV and 249 mV, far lower than those of nickel foam (357 mV and 437 mV), copper foam (467 mV and 607 mV), commercial iridium dioxide (358 mV and 521 mV), and copper nanoframework electrode (372 mV and 523 mV); and its Tafel slope is only 19.87 mV·dec -1 This is far lower than that of nickel foam (58.71 mV·dec). -1 ), copper foam (168.34 mV·dec) -1 ), commercial iridium dioxide (120.92 mV·dec) -1 ), copper nanoframework electrode (92.68 mV·dec) -1 This reflects its superior oxygen evolution reaction kinetics.

[0088] Furthermore, at an overpotential of 350 mV, the switching frequency (TOF) of this electrode reaches as high as 2.32 s. -1 It not only far exceeds that of nickel foam (1.04 s) -1 ), copper foam (0.030 s) -1 ), copper nanoframework (0.021 s -1 ), even slightly higher than commercial iridium dioxide (2.12 s), -1 This fully demonstrates its excellent and outstanding intrinsic catalytic activity. The combined performance parameters mentioned above confirm that the prepared copper framework / ternary alloy catalytic electrode possesses superior intrinsic catalytic activity and potential for service in water electrolysis and oxygen evolution.

[0089] Electrochemical tests were conducted on the above three materials (a composite catalytic material based on copper foam, a composite catalytic material based on nickel foam, and the copper-framework composite catalytic material of Example 1) to further evaluate their electrocatalytic oxygen evolution performance. Among them, the copper-framework / ternary alloy catalytic electrode had the highest electrochemical active area (348.25 cm²). 2 ), far exceeding that of nickel foam (269.25 cm). 2 ) and foam copper (198 cm) 2A nickel-iron-cobalt catalytic electrode supported on a copper nanoframework substrate was successfully developed. This result fully demonstrates that the hierarchical structure of the copper nanoframework provides a larger specific surface area, effectively exposing more active sites and significantly enhancing the electrochemical active area of ​​the electrode interface reaction. Compared to nickel foam and copper foam substrates, the copper nanoframework not only possesses an excellent conductive network, but its unique three-dimensional hierarchical morphology also optimizes electrolyte penetration and bubble desorption, enhancing oxygen evolution performance from both the perspectives of catalytic sites in water electrolysis and reaction mass transfer. These advantages collectively highlight the structural superiority and performance competitiveness of the copper framework / ternary alloy catalytic electrode in the field of water electrolysis catalysis.

[0090] like Figure 18 As shown, the copper framework / ternary alloy catalytic electrode at 10 mA·cm -2 It exhibits an overpotential of 202 mV at low current densities, comparable to the electrode overpotential (200 mV) of nickel-iron-cobalt alloy electrodeposited on a nickel foam substrate, while at 100 mA·cm⁻¹... -2 The overpotential at high current density is 249 mV, which is advantageous compared to the nickel foam substrate (252 mV). Furthermore, the Tafel slope of the copper-framework / ternary alloy catalytic electrode is as low as 19.87 mV·dec. -1 This is lower than that of nickel foam (27.75 mV·dec). -1 ) and copper foam (30.67 mV·dec) -1 The nickel-iron-cobalt alloy electrode confirmed that the copper skeleton / ternary alloy catalytic electrode has strong intrinsic activity.

[0091] like Figure 19 As shown, the copper framework catalytic electrode with electrodeposited nickel-iron alloy is at 1125 cm⁻¹. -1 A vibrational peak that gradually intensifies with increasing potential was observed at 1400–1600 cm⁻¹. This peak is attributed to OO*, a characteristic intermediate of the lattice oxygen participation mechanism (LOM). -1 The two vibrational peaks within the range are residual organic matter from the sample preparation process and do not affect the determination of the main catalytic reaction pathway. 。 Located at 1639 cm -1 The peak at 3230 cm corresponds to the bending vibration of the interfacial water, while the peak at 3230 cm corresponds to the bending vibration of the interfacial water. -1 The broad peak at that location is attributed to the *OH vibration. The combined in-situ infrared results confirm that the iron-doped modified copper framework catalytic electrode primarily follows the LOM mechanism during the alkaline oxygen evolution reaction.

[0092] For the nickel-iron binary system, iron doping effectively enhances the covalent bonding of Ni-O, increases the activity of lattice oxygen, and makes it easier for lattice oxygen to participate in the reaction, thereby activating the LOM reaction pathway. Therefore, the nickel-iron system at 1125 cm⁻¹... -1 An OO* signal appears. For the nickel-iron-cobalt ternary system, such as...Figure 20 As shown, cobalt doping optimizes the covalent nature of Ni-O, preventing excessive covalent nature from dominating the LOM mechanism while ensuring the smooth progress of the AEM adsorbate evolution mechanism. Furthermore, cobalt doping may further shift the d-band center upward, optimizing the adsorption of the *OOH intermediate, reducing the energy barrier of the AEM reaction pathway, and ultimately achieving synergistic effects of the two reaction pathways.

[0093] To simulate the harsh conditions under which electrode materials in actual industrial electrolyzers operate, this invention uses a 30 wt.% KOH solution as the electrolyte, and the electrolyzer temperature is controlled at 60 ℃. This maximizes the replication of the real reaction environment of industrial water electrolysis, ensuring the industrial reference value of the test results. Performance tests were conducted using an electrolyzer assembled with the copper skeleton / ternary alloy catalytic electrode prepared in Example 1 as the anode and the latest generation of commercially available Raney nickel as the cathode. A comparative performance test was also conducted using an electrolyzer assembled with dual Raney nickel electrodes.

[0094] like Figure 21 As shown, at 250, 500, and 1000 mA·cm -2 The cell voltages of the self-equipped electrolytic cell at the given current densities were 1.596, 1.664, and 1.786 V, corresponding to DC energy consumptions of 3.82, 3.98, and 4.27 kWh / Nm³. 3 (i.e., 42.5, 44.3, and 47.5 kWh / kg H2); while under the same operating conditions, the cell voltages of the latest generation of commercially available dual Raney nickel electrodes are 1.751, 1.875, and 2.177 V, respectively, corresponding to DC energy consumptions of 4.19, 4.49, and 5.21 kWh / Nm. 3 (i.e., 46.6, 50.0, and 57.9 kWh / kg H2).

[0095] The above results demonstrate that, compared to commercially available mainstream dual Raney nickel electrodes, the copper-framework / ternary alloy catalytic electrode prepared in this study exhibits superior performance in industrial water electrolysis under industrial-grade high current density conditions. Specifically, at industrial-grade high current densities, the chamber voltage decreases by an average of 0.15–0.39 V, and the DC energy consumption decreases by an average of 0.37–0.94 kWh / Nm³. 3The energy consumption reduction is significant. The copper-framework / ternary alloy catalytic electrode exhibits lower electrolysis energy consumption at industrial-grade current densities, fully demonstrating its excellent industrial service potential and application value. This advantage proves that the copper-framework / ternary alloy catalytic electrode can adapt to the harsh operating conditions of industrial water electrolysis, effectively reducing energy loss during the electrolysis process, and possessing excellent industrial service performance and cost advantages. Its low energy consumption characteristic not only significantly improves the economics of industrial water electrolysis for hydrogen production, but also reduces energy consumption and carbon emissions, providing reliable electrode material support for the efficient and low-cost development of industrial water electrolysis for hydrogen production technology, and further promoting the process of moving this catalytic electrode from laboratory research and development to large-scale industrial application.

[0096] Subsequently, to systematically evaluate the long-term service stability of the copper-framework / ternary alloy catalytic electrode under harsh industrial conditions, a multi-current step stability testing platform was further constructed to simulate the actual operating conditions of alkaline water electrolysis and to conduct a long-term constant current stability evaluation. A 10 mA·cm² test was selected. -2 100 mA·cm -2 200 mA·cm -2 500 mA·cm -2 A continuous constant-current step stability test was conducted for up to 40 hours, covering typical industrial-grade current densities from low to high, to comprehensively examine the electrode's ability to maintain catalytic performance, structural integrity, and electrochemical stability under varying operating conditions and high current densities. Simultaneously, a commonly used industrial anode electrode, nickel mesh, was introduced as a control group, and parallel tests were carried out under identical electrolyte environments, temperatures, and stability test parameters to directly compare the performance advantages and stability differences of this material during long-term service, providing direct experimental evidence for its industrial application.

[0097] Under the above test conditions, the stability of the copper framework / ternary alloy catalytic electrode prepared in this invention was compared with that of a commercial nickel mesh. The results are as follows: Figure 22 As shown, the copper-framework / ternary alloy catalytic electrode exhibits good current adaptability: at 100 mA·cm⁻¹ -2 Under these conditions, the overpotential stabilized at approximately 212 mV within 10 hours; the current rose to 200 mA·cm⁻¹. -2 At that time, the overpotential remained at 242 mV, with fluctuations of less than 20 mV over 10 hours; when it rose to 500 mA·cm⁻¹, the overpotential was maintained at 242 mV. -2 At that time, the overpotential was 281 mV, with relatively small fluctuations; when the current dropped to 10 mA·cm -2 At that time, the overpotential was only 173 mV. After 40 hours of continuous testing, even at 500 mA·cm⁻¹, the overpotential remained unchanged. -2 Even under high current density, the electrode can still operate stably, showing good prospects for industrial applications.

[0098] In contrast, the nickel mesh operated under the same conditions for 40 h at 100 mA·cm -2 Ten hours later, the overpotential increased from the initial 370 mV to 451 mV, an increase of 81 mV; at 200 mA·cm -2 Under these conditions, the overpotential also increased significantly within 10 hours; and the overpotential fluctuations became more pronounced with increasing current density. After long-term service, the copper nanoframework structure remained intact and morphologically stable, without significant collapse, corrosion, dissolution, or structural degradation, fully demonstrating the excellent structural stability and mechanical support capability of the copper-based framework under strongly alkaline and high current density conditions. In summary, the stability of the copper framework / ternary alloy catalytic electrode is significantly better than that of the nickel mesh.

[0099] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a copper-framework composite catalytic material, characterized in that, Includes the following steps: The pretreated copper foam was immersed in a chemical oxidation solution for alkaline etching. The blue product obtained by alkaline etching was calcined in air. After cooling to room temperature, the black product obtained by calcination was reduced with hydrogen to obtain copper nanoframework. A nickel-iron-cobalt ternary alloy catalytic layer was loaded onto the copper nanoframework using a constant current electrodeposition process to obtain the copper-framework composite catalytic material. When using constant current for electrodeposition, the electrodeposition time is 5–20 min, and the current density is -20 to -40 mA·cm⁻¹. -2 .

2. The method for preparing the copper-framework composite catalytic material according to claim 1, characterized in that, The chemical oxidizing solution is composed of water, ammonium persulfate, and sodium hydroxide.

3. The method for preparing the copper-framework composite catalytic material according to claim 2, characterized in that, In the chemical oxidation solution, the concentration of ammonium persulfate is 0.125 M and the concentration of sodium hydroxide is 2.5 M.

4. The method for preparing the copper-framework composite catalytic material according to claim 1, characterized in that, The alkaline etching time is 20 minutes.

5. The method for preparing the copper-framework composite catalytic material according to claim 1, characterized in that, The baking process was carried out at a temperature of 180°C for 60 minutes.

6. The method for preparing the copper-framework composite catalytic material according to claim 1, characterized in that, The hydrogen reduction was performed at a temperature of 285°C for 150 min, with argon and hydrogen flow rates of 180 sccm and 20 sccm, respectively.

7. The method for preparing the copper-framework composite catalytic material according to claim 1, characterized in that, The electrodeposition solution used in the electrodeposition process consists of water, nickel nitrate hexahydrate, ferrous sulfate heptahydrate, cobalt nitrate hexahydrate, sodium citrate dihydrate, boric acid, and sodium nitrate.

8. The method for preparing the copper-framework composite catalytic material according to claim 7, characterized in that, In the electrodeposition plating solution, the concentrations of nickel nitrate hexahydrate, ferrous sulfate heptahydrate, cobalt nitrate hexahydrate, sodium citrate dihydrate, boric acid, and sodium nitrate are 0.15 M, 0.1-0.3 M, and the pH of the electrodeposition plating solution is 3-4.

9. A copper-framework composite catalytic material, characterized in that, It is prepared according to any one of claims 1 to 8.

10. The application of the copper-framework composite catalytic material as described in claim 9 in oxygen evolution through water electrolysis.

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