Cobalt-copper-based oxygen evolution electrocatalyst and preparation method and application thereof

Abstract

The invention discloses a cobalt-copper-based oxygen evolution electrocatalyst and a preparation method and application thereof, and belongs to the technical field of electrocatalytic water decomposition, foamed nickel is added into an aqueous solution containing a cobalt source and a copper source, a hydrothermal reaction is performed at 140 DEG C, cooling, washing and drying are performed to obtain a CoCuOH / Co3O4 composite material, and a CuO / Co3O4 composite material is obtained after heat treatment and cooling. Immersing the Cu2O / Co3O4 composite material into a phytic acid solution to etch for 5 hours, and washing and drying to obtain the Cu2O / Co3O4 composite material; the cobalt-copper-based oxygen evolution electrocatalyst is obtained by carrying out reduction treatment through a sodium borohydride solution and carrying out washing and drying, the cobalt-copper-based oxygen evolution electrocatalyst can continuously run for 450 hours or more under the current density of 100 mA. Cm <-2 > in an oxygen evolution reaction, and a full-water decomposition electrolytic cell assembled by the cobalt-copper-based oxygen evolution electrocatalyst can stably run for 560 hours or more under the same current density. And excellent durability and practical application potential are shown.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic water splitting technology, and particularly relates to a cobalt-copper based oxygen evolution electrocatalyst, its preparation method, and its application. Background Technology

[0002] In green hydrogen production technology, water electrolysis is a key pathway to achieve efficient and clean hydrogen production. The oxygen evolution reaction (OER) under alkaline conditions, involving multiple electron transfer processes, has slow reaction kinetics and often becomes the rate-determining step limiting overall electrolysis efficiency. Improving OER performance is mainly limited by two key factors: the interfacial interaction between the electrode and the electrolyte, and the charge transfer capability within the electrode material. Specifically, the hydrophilicity of the electrode surface directly affects the spread and penetration of the electrolyte, while charge transfer within the material relies on highly ordered conductive channels. The construction of a built-in electric field helps to regulate charge distribution and lower the reaction energy barrier, thereby promoting rapid electron and ion transport. Although traditional cobalt-based and copper-based oxides possess certain intrinsic OER activity, their surface hydrophilicity is generally poor, resulting in significant charge transfer resistance and limiting their practical catalytic efficiency. Previous studies often employed single strategies (such as structural modulation or elemental doping) for modification, making it difficult to synergistically optimize interfacial hydrophilicity and internal charge transport. Therefore, there is an urgent need to develop novel electrode material systems to simultaneously overcome these dual challenges and promote the practical application of water electrolysis technology. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention proposes a cobalt-copper based oxygen evolution electrocatalyst, its preparation method, and its application.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] This invention provides a method for preparing a cobalt-copper based oxygen evolution electrocatalyst, comprising the following steps:

[0006] Pretreated nickel foam was added to an aqueous solution containing cobalt and copper sources, and a hydrothermal reaction was carried out at 140°C to prepare a CoCuOH / Co3O4 composite material.

[0007] The CoCuOH / Co3O4 composite material was subjected to heat treatment and then cooled to obtain CuO / Co3O4 composite material.

[0008] The CuO / Co3O4 composite material was etched in phytic acid solution for 5 hours, followed by washing and drying to obtain Cu2O / Co3O4 composite material. Finally, the Cu2O / Co3O4 composite material was reduced with sodium borohydride solution to obtain Cu2O / Co x O composite material, namely Cu2O / Co xThe O composite material is the cobalt-copper based oxygen evolution electrocatalyst, wherein Co x O is a complex of Co3O4 and CoO; for simplicity and convenience, it will be consistently referred to as Co. x O is used to refer to it.

[0009] This invention effectively modulates the morphology and structure of a cobalt-copper-based oxygen evolution electrocatalyst by precisely controlling the hydrothermal reaction temperature. Experimental results show that when hydrothermally treated at 140℃, the resulting composite material exhibits a unique nanoflower-like morphology, which is beneficial for improving charge transport performance. After etching with phytic acid solution and reduction treatment with sodium borohydride, the obtained Cu₂O / Co... x The O catalyst exhibits excellent oxygen evolution reaction (OER) activity and long-term stability; its OER performance is superior to that of the noble metal benchmark catalyst RuO2 / C, and the water splitting system composed of this catalyst and Pt / C outperforms the noble metal combination of Pt / C and RuO2 / C in overall performance. Characterization methods such as XPS, zeta potential, and UPS, along with built-in electric field theory analysis, further confirm that the cobalt-copper-based OER electrocatalyst of this invention possesses a high charge transfer rate, providing a theoretical basis for its superior catalytic performance. The introduced Cu defects further enhance this effect by generating active sites and stabilizing the interface; this synergistic effect ensures efficient and stable charge transfer. The hierarchical flower-like structure combined with the superhydrophilic surface of the cobalt-copper-based OER electrocatalyst of this invention guarantees excellent mass transport capabilities, thus exhibiting superior OER performance. The cobalt-copper-based OER electrocatalyst prepared in this invention is comparable to noble metal catalysts in catalytic activity, and its preparation process is simple and low-cost, showing good application potential in industrial water electrolysis for hydrogen production. Furthermore, the strategy of combining phytic acid solution etching with sodium borohydride reduction employed in the method of this invention also provides a useful reference for the development of other transition metal-based catalysts.

[0010] This invention uses nickel foam as an electrocatalyst support, which exhibits the following comprehensive advantages in the water electrolysis hydrogen production process:

[0011] 1. Highly optimized conductivity system

[0012] Nickel foam possesses excellent electronic conductivity, which can effectively promote charge transport during the catalytic process. Its highly conductive structure helps reduce the interfacial resistance between the electrode and the catalyst, enabling rapid accumulation and transfer of reaction charges, thereby improving overall catalytic efficiency.

[0013] 2. High specific surface area and abundant active sites

[0014] The three-dimensional porous network of nickel foam provides abundant specific surface area, which is beneficial for the uniform dispersion and full exposure of the active components of the catalyst, and significantly enhances the reaction of reactants (such as H2O, OH-). - The contact efficiency between the catalyst site and other catalytic sites.

[0015] 3. Efficient mass transfer channels and reaction kinetics

[0016] The open-pore structure of nickel foam not only facilitates the uniform attachment of the catalyst but also accelerates the diffusion process of reactants and gaseous products (such as O2 and H2), reducing mass transfer resistance and thus increasing the reaction rate. Simultaneously, the uniform supported structure helps maintain the long-term stability of the catalyst and reduces the aggregation or shedding of active components.

[0017] 4. Good process adaptability and cost advantage

[0018] Nickel foam is economical, has a mature preparation process, and exhibits good mechanical stability, making it suitable for large-scale production. Its synergistic effect with transition metal catalysts helps reduce dependence on precious metals, enhancing the economic viability and industrial applicability of this invention.

[0019] Furthermore, the pretreatment method for the nickel foam is as follows: the nickel foam is cut into small pieces, then ultrasonically washed in sulfuric acid solution, deionized water and ethanol in sequence, rinsed with deionized water and air-dried.

[0020] Furthermore, the aqueous solution containing cobalt and copper sources is prepared by dissolving urea, ammonium fluoride, cobalt nitrate hexahydrate and copper nitrate trihydrate in water.

[0021] Furthermore, the molar ratio of urea, ammonium fluoride, cobalt nitrate hexahydrate, and copper nitrate trihydrate is 25:20:12.5:6.

[0022] Furthermore, the hydrothermal reaction time is 12 h.

[0023] Furthermore, the heat treatment is carried out in an inert gas atmosphere at a temperature of 400°C, a holding time of 3 hours, and a heating rate of 5°C / min. -1 .

[0024] Furthermore, the phytic acid solution is obtained by mixing phytic acid and ethanol in a volume ratio of 1:1.

[0025] Furthermore, the concentration of the sodium borohydride solution is 0.5 wt%; the reduction treatment time is 10 h.

[0026] The present invention also provides a cobalt-copper-based oxygen evolution electrocatalyst prepared according to the above preparation method.

[0027] The present invention also provides the application of the above-mentioned cobalt-copper-based oxygen evolution electrocatalyst in total water splitting, wherein the cobalt-copper-based oxygen evolution electrocatalyst is used as an oxygen evolution electrocatalyst.

[0028] The cobalt-copper based oxygen evolution electrocatalyst prepared by this invention can be widely used in alkaline electrolyzers. When used for total water splitting, it achieves high efficiency at 100 mA. -2 Its stability reached 560 hours, providing key technical support for the large-scale application of green hydrogen energy.

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

[0030] 1. Highly efficient oxygen evolution reaction catalytic performance: The cobalt-copper based oxygen evolution electrocatalyst of the present invention exhibits superior oxygen evolution reaction (OER) activity in a single material system, which can significantly reduce the overpotential in the water splitting process and improve the overall energy conversion efficiency.

[0031] 2. Excellent conductivity and charge transport properties: The cobalt-copper based oxygen evolution electrocatalyst of this invention utilizes highly conductive nickel foam as a support, ensuring rapid electron conduction during the reaction, effectively reducing interfacial resistance, and improving reaction kinetics. Compared to conventional carbon-based supports or insulating substrates, this invention successfully alleviates the problems of limited charge accumulation and transport.

[0032] 3. Abundant active interfaces and optimized mass transfer: By synthesizing a cobalt-copper-based oxygen evolution electrocatalyst with a nanoflower-like morphology, an open porous structure was constructed, which not only significantly increased the number of exposed catalytic active sites but also promoted the reaction of reactants (such as OH-) - The rapid diffusion of reactants and products (such as O2) significantly reduces mass transfer resistance and enhances the contact efficiency between reactants and the catalytic interface.

[0033] 4. Excellent dispersibility and structural stability: Compared with traditional powder catalysts, the cobalt-copper-based oxygen evolution electrocatalyst of this invention effectively avoids the aggregation of active components and improves the utilization efficiency of catalytic sites. Through the synergistic effect between the support and the active components, the structural stability and anti-dissolution ability of the cobalt-copper-based oxygen evolution electrocatalyst are enhanced under high-potential operating conditions, thus extending its service life.

[0034] 5. Excellent process scalability and cost advantages: The cobalt-copper based oxygen evolution electrocatalyst of this invention is entirely based on non-precious metal materials (such as Co, Cu, etc.), which significantly reduces raw material costs. The preparation process is simple, suitable for large-scale production, and has good economic benefits and industrial application prospects.

[0035] 6. Excellent long-term operational stability: The cobalt-copper based oxygen evolution electrocatalyst of this invention exhibits excellent long-term operational stability at 100 mA·cm⁻¹ during the oxygen evolution reaction. -2 It can operate continuously for more than 450 hours at current density, and the full water splitting electrolyzer assembled from it can operate stably for more than 560 hours at the same current density, demonstrating excellent durability and practical application potential. Attached Figure Description

[0036] 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:

[0037] Figure 1 The cobalt-copper based oxygen evolution electrocatalyst Cu2O / Co prepared in Example 1 of this invention x X-ray powder diffraction pattern of O composite material;

[0038] Figure 2 X-ray powder diffraction patterns of the CoCuOH / Co3O4 composite material, CuO / Co3O4 composite material and Cu2O / Co3O4 composite material prepared in Example 1;

[0039] Figure 3 Co prepared for Comparative Example 6 x X-ray powder diffraction patterns of O material and Cu2O material prepared in Comparative Example 7;

[0040] Figure 4 In Figure a, scanned electron microscope images of the CoCuOH / Co3O4 composite material, CuO / Co3O4 composite material, and Cu2O / Co3O4 composite material prepared in Example 1 are shown. In Figure b, scanned electron microscope images of the Cu2O / Co3O4 composite material prepared in Example 1 are shown. x Scanning electron microscope images of O composite materials, where 1 is the CoCuOH / Co3O4 composite material, 2 is the CuO / Co3O4 composite material, and 3 is the Cu2O / Co3O4 composite material.

[0041] Figure 5 Cu2O / Co prepared in Example 1 x Electron micrographs of O composite material, where a is a transmission electron microscope image, b is a high-resolution transmission electron microscope image, c is the distribution of each element, and d is a selected area electron diffraction (SAED) pattern, where 1 is Cu2O, 2 is Cu2O, 3 is CoO, 4 is Co3O4, and 5 is Co3O4.

[0042] Figure 6 In Example 1, 'a' represents the Cu₂O / Co mixture prepared in this study. x N2 adsorption / desorption isotherms and pore size distribution of the O composite material, b is the Co prepared in Comparative Example 6. x N2 adsorption / desorption isotherms and pore size distribution of Cu2O material, c is N2 adsorption / desorption isotherms and pore size distribution of Cu2O material prepared in Comparative Example 7;

[0043] Figure 7 In Example 1, 'a' represents the Cu₂O / Co mixture prepared in this study. x O composite material, Co prepared in Comparative Example 2x Electron paramagnetic resonance (EPR) spectra of Cu2O material prepared in Example 1 and Comparative Example 3, b is the Cu2O / Co material prepared in Example 1. x Electron paramagnetic resonance (EPR) spectra of the O composite material, the CoCuOH / Co3O4 composite material prepared in Comparative Example 3, the CuO / Co3O4 composite material prepared in Comparative Example 4, and the Cu2O / Co3O4 composite material prepared in Comparative Example 5.

[0044] Figure 8 Cu2O / Co prepared in Example 1 x O composite material, Co prepared in Comparative Example 6 x Zeta potential diagrams of O material and Cu2O material prepared in Comparative Example 7 in 1.0 M KOH solution;

[0045] Figure 9 Cu2O / Co prepared in Example 1 x O composite material, Co prepared in Comparative Example 6 x Contact angle diagrams of O material and Cu2O material prepared in Comparative Example 7;

[0046] Figure 10 Cu2O / Co prepared in Example 1 x O composite material, Co prepared in Comparative Example 6 x CV curves of O material and Cu2O material prepared in Comparative Example 7;

[0047] Figure 11 Cu2O / Co prepared in Example 1 x O composite material, Co prepared in Comparative Example 6 x X-ray photoelectron spectra of O material and Cu2O material prepared in Comparative Example 7; where a is the 2p spectrum of Co, b is the 2p spectrum of Cu, and c is the 1s spectrum of O.

[0048] Figure 12 This is a schematic diagram showing the electrochemical performance test results of the electrocatalysts prepared in Examples 1, 2-7, and 7 in 1.0 M KOH solution for oxygen evolution. In the diagram, a is the linear scan curve of the electrocatalytic oxygen evolution; b is the overpotential curve at different current densities; c is the Tafel slope diagram; d is the double-layer capacitance diagram; and e is the Cu₂O / Co electrocatalyst prepared in Example 1. x Bode phase diagrams of the O composite material at different potentials, f is the Cu2O / Co prepared in Example 1. x O composite material, Co prepared in Comparative Example 6 x A comparison of the phase angle versus application potential for different catalysts of O material and Cu2O material prepared in Comparative Example 7; g is the Cu2O / Co prepared in Example 1. xO composite materials (This work) and OER catalysts reported in the prior art at 100 mA·cm -2 A comparison of overpotential and Tafel slope; h represents the Cu2O / Co oxygen evolution electrocatalyst prepared in Example 1. x O composite material at 100 mA·cm -2 The results of the three-electrode stability test are shown in the figure below.

[0049] Figure 13 Co prepared for Comparative Example 6 x Bode phase diagrams of O material and Cu2O material prepared in Comparative Example 7 at different potentials;

[0050] Figure 14 The graphs show the electrochemical oxygen evolution performance of the materials prepared in Examples 1 and Comparative Examples 8-10 as electrocatalysts, where a is the linear scan curve of electrocatalytic oxygen evolution; b is the Tafel slope diagram; c is the double-layer capacitance diagram; and d is the electrochemical impedance spectroscopy (EIS) for Cu2O / Co. x O represents Example 1, 3h represents Comparative Example 8, 7h represents Comparative Example 9, and 9h represents Comparative Example 10.

[0051] Figure 15 The graphs show the electrochemical oxygen evolution performance of the materials prepared in Examples 1 and Comparative Examples 11-14 as electrocatalysts, where a is the linear scan curve of electrocatalytic oxygen evolution; b is the Tafel slope diagram; c is the double-layer capacitance diagram; and d is the electrochemical impedance spectroscopy (EIS) for Cu2O / Co. x O represents Example 1, 100℃ represents Comparative Example 11, 120℃ represents Comparative Example 12, 160℃ represents Comparative Example 13, and 180℃ represents Comparative Example 14.

[0052] Figure 16 Cu2O / Co prepared in Example 1 x Schematic diagram of the complete water decomposition process and results of Cu2O / Co composite material, where a is a schematic diagram of complete water decomposition; b is a two-electrode test, with an inset showing the comparison of electrode performance results; c is the Cu2O / Co composite material prepared in Example 1. x Faraday test diagram of O composite material; d is Cu2O / Co prepared in Example 1. x The two-electrode system composed of O composite material (This work) is compared with the voltage of the full water splitting cell of oxygen evolution electrocatalysts reported in the prior art; e represents the Cu2O / Co prepared in Example 1. x The two-electrode system composed of O composite material performs total water splitting at 100 mA -2 Stability test results at time; f represents the Cu2O / Co prepared in Example 1. x Images of total water decomposition of O composite materials under solar and wind power cells. Detailed Implementation

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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 obvious to those skilled in the art. This specification and embodiments are merely exemplary.

[0057] 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.

[0058] An embodiment of the present invention provides a method for preparing a cobalt-copper-based oxygen evolution electrocatalyst, comprising the following steps:

[0059] Pretreated nickel foam was added to an aqueous solution containing cobalt and copper sources and subjected to a hydrothermal reaction at 140°C. Then, the mixture was cooled, washed, and dried sequentially to obtain the CoCuOH / Co3O4 composite material.

[0060] The CoCuOH / Co3O4 composite material was heat-treated and then cooled to obtain the CuO / Co3O4 composite material.

[0061] Subsequently, the CuO / Co3O4 composite material was immersed in phytic acid solution for etching for 5 hours. After washing and drying, Cu2O / Co3O4 composite material was obtained. Finally, the Cu2O / Co3O4 composite material was reduced with sodium borohydride solution, and after washing and drying, Cu2O / Co x O composite material (Co) x O is a complex of Co3O4 and CoO), Cu2O / Co x O composite material is a cobalt-copper based oxygen evolution electrocatalyst.

[0062] In a preferred embodiment of the present invention, the pretreatment method for nickel foam is as follows: the nickel foam is cut into small pieces, and then ultrasonically washed in sulfuric acid solution, deionized water and ethanol in sequence, rinsed with deionized water and air-dried.

[0063] For example, the pretreatment method for nickel foam is as follows: cut the nickel foam into 1.5 cm × 3 cm pieces, and then ultrasonically wash them for 15 minutes each in 0.5 mol / L sulfuric acid solution, deionized water and ethanol, respectively. Rinse them with deionized water and let them air dry for later use.

[0064] In a preferred embodiment of the present invention, the aqueous solution containing cobalt and copper sources is prepared by dissolving urea, ammonium fluoride, cobalt nitrate hexahydrate and copper nitrate trihydrate in water.

[0065] In a preferred embodiment of the present invention, the molar ratio of urea, ammonium fluoride, cobalt nitrate hexahydrate and copper nitrate trihydrate is 25:20:12.5:6.

[0066] In a preferred embodiment of the present invention, the hydrothermal reaction time is 12 h.

[0067] In a preferred embodiment of the present invention, the heat treatment is carried out in an inert gas atmosphere (such as nitrogen), the heat treatment temperature is 400°C, the holding time is 3 h, and the heating rate is 5 °C·min. -1 .

[0068] For example, when preparing Cu2O / Co3O4 composite material, the washing and drying steps are as follows: thoroughly rinse with deionized water and ethanol in sequence, and then vacuum dry at 60°C for 6 h.

[0069] In a preferred embodiment of the present invention, the phytic acid solution is obtained by mixing phytic acid and ethanol in a volume ratio of 1:1.

[0070] For example, the preparation of Cu2O / Co x The O composite material was washed and dried by rinsing it thoroughly with deionized water and ethanol in sequence, and then vacuum dried at 60°C for 6 h.

[0071] In a preferred embodiment of the present invention, the concentration of sodium borohydride solution is 0.5 wt%; the reduction treatment time is 10 h.

[0072] An embodiment of the present invention also provides a cobalt-copper-based oxygen evolution electrocatalyst prepared according to the above preparation method.

[0073] The embodiments of the present invention also provide the application of the above-mentioned cobalt-copper-based oxygen evolution electrocatalyst in total water splitting, wherein the cobalt-copper-based oxygen evolution electrocatalyst is used as an oxygen evolution electrocatalyst.

[0074] This invention employs a two-stage processing method combining phytic acid solution etching and sodium borohydride reduction to successfully construct a composite catalyst system with high oxygen evolution activity. Under hydrothermal conditions of 140℃, the resulting cobalt-copper based oxygen evolution electrocatalyst exhibits a nanoflower-like structure and excellent charge transport performance. This catalyst demonstrates superior oxygen evolution electrocatalytic activity and long-term stability in an alkaline environment, with OER performance exceeding that of the noble metal reference catalyst RuO2 / C. Furthermore, when paired with Pt / C to form a complete water splitting system, its performance is also superior to the noble metal catalyst combination of Pt / C and RuO2 / C. This invention offers a simple and low-cost process, providing a new approach for the design and preparation of non-noble metal-based high-efficiency oxygen evolution catalysts.

[0075] In the following embodiments of the present invention, the phytic acid solution is prepared by mixing 10 mL of phytic acid (PA) and 10 mL of ethanol (C2H5OH) and stirring until homogeneous.

[0076] In the following embodiments of the present invention, the sodium borohydride aqueous solution is prepared by dissolving 0.1 g of sodium borohydride in 20 mL of deionized water and stirring until homogeneous.

[0077] In this invention, electrochemical performance testing is performed using both three-electrode and two-electrode systems, with the specific steps as follows:

[0078] 1. Oxygen Evolution Reaction (OER) Test:

[0079] Electrochemical tests were performed on a Bio-Logic VMP3 electrochemical workstation (France) using a three-electrode system. The working electrode was the material prepared in each example or comparative example; the counter electrode was a graphite plate; the reference electrode was a saturated calomel electrode (SCE); the electrolyte was a 1.0 M KOH solution; the test temperature was 25 °C; and the scan rate was 5 mV / s. All potentials were converted to values ​​relative to a reversible hydrogen electrode (RHE) according to the Nernst equation and solution impedance compensation was performed. The conversion formula is as follows:

[0080] E RHE = E SCE +0.241+0.059 pH-iR

[0081] Where i is the test current (A), R is the solution impedance (Ω), and E RHE This is the reversible hydrogen electrode potential. E SCE This represents the potential of a standard silver chloride electrode.

[0082] 2. Total water decomposition test:

[0083] The electrolysis was performed using a two-electrode system on an electrochemical workstation (Bio-Logic VMP3, France). The electrolytic cell consisted of an anode and a cathode. The electrolyte was a 1.0 mol / L KOH solution, the temperature was 25 °C, the scan rate was 2 mV / s, and the voltage scan range was 0–2.5 V. The anode (oxygen evolution reaction) used was the Cu₂O / Co electrolyte prepared in Example 1. x O-composite catalyst or RuO2 material as in Comparative Example 1; cathode (hydrogen evolution reaction): Pt / C electrode as in Comparative Example 2 was used as the control electrode. This test method can systematically evaluate the electrochemical performance and stability of the catalyst in oxygen evolution and total water splitting reactions.

[0084] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0085] All raw materials used in the embodiments and comparative examples of this invention were purchased commercially. As an example, the nickel foam was purchased from Kunshan Guangjiayuan New Materials Co., Ltd., model NI90; the Pt / C catalyst was purchased from Xingyao Biotechnology Co., Ltd., model 7440-06-4; and the RuO2 powder was purchased from Hubei Weishi Chemical Reagent Co., Ltd., model 12036-10-1.

[0086] 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.

[0087] The technical solution of the present invention will be further illustrated by the following embodiments.

[0088] Example 1

[0089] This embodiment provides a method for preparing a cobalt-copper based oxygen evolution electrocatalyst, the steps of which are as follows:

[0090] (1) Pretreatment of nickel foam: Cut the nickel foam into 1.5 cm × 3 cm pieces, and then ultrasonically wash them in 0.5 mol / L sulfuric acid solution, deionized water and ethanol for 15 minutes each. Rinse them with deionized water and let them air dry for later use.

[0091] (2) Preparation of reaction solution: Weigh 2.5 mmol urea, 2.0 mmol ammonium fluoride, 1.25 mmol cobalt nitrate hexahydrate and 0.6 mmol copper nitrate trihydrate and add them to 40 mL of deionized water solution. Stir for 30 minutes to obtain a homogeneous solution.

[0092] (3) Hydrothermal reaction: The cleaned nickel foam from step (1) is placed in the homogeneous solution prepared in step (2), placed in a reaction vessel, and then kept in an oven at 140 °C for 12 h. After the reaction is completed, it is naturally cooled to room temperature, the synthesized product is rinsed with deionized water, and then placed in an oven at 60 °C for 3 h to obtain the CoCuOH / Co3O4 composite material.

[0093] (4) Heat treatment reaction: The CoCuOH / Co3O4 composite material obtained in step (3) was placed in a tube furnace and heated at 5 °C·min under N2 atmosphere. -1 The temperature was increased to 400 °C at a certain rate, held for 3 h, and then naturally cooled to room temperature to obtain CuO / Co3O4 composite material.

[0094] (5) Phytic acid etching and soaking reaction: The CuO / Co3O4 composite material obtained in step (4) was immersed in phytic acid solution (a solution composed of 10 mL PA and 10 mL C2H5OH, the same below) for 5 h for etching, and then thoroughly rinsed with deionized water and ethanol in sequence, and then vacuum dried at 60 °C for 6 h to obtain Cu2O / Co3O4 composite material.

[0095] (6) Sodium borohydride reduction reaction: The Cu2O / Co3O4 composite material obtained in step (5) was placed in a sodium borohydride aqueous solution (0.1 g of sodium borohydride was dissolved in 20 mL of deionized water and stirred evenly; the preparation method of sodium borohydride aqueous solution is the same below), and after soaking and reducing treatment for 10 h, it was thoroughly rinsed with deionized water and ethanol in sequence, and then vacuum dried at 60 °C for 6 h to finally obtain the target electrocatalyst - cobalt copper-based oxygen evolution electrocatalyst, which is Cu2O / Co x O composite material (Co) x O is a complex of Co3O4 and CoO (the same applies below).

[0096] Comparative Example 1 (Pt / C electrode)

[0097] Weigh 2 mg of Pt / C catalyst and add it to a mixed solution prepared by 200 µL of deionized water, 200 µL of anhydrous ethanol, and 10 µL of Nafion solution (5 wt%). Sonicate the solution for 30 minutes to ensure uniform dispersion, obtaining a slurry. Coat the resulting slurry onto a 1 cm thick substrate. 2A Pt / C electrode was obtained by drying the nickel foam surface at room temperature and used as a control electrode.

[0098] Comparative Example 2 (RuO2 electrode)

[0099] Weigh 2 mg of RuO2 powder and add it to a mixed solution consisting of 200 µL of deionized water, 200 µL of anhydrous ethanol, and 10 µL of Nafion solution (5 wt%). Disperse the mixture ultrasonically for 30 minutes to obtain a slurry. Add the slurry evenly dropwise to a depth of 1 cm. 2 A RuO2 electrode was obtained by drying the nickel foam substrate at room temperature and used as a control electrode.

[0100] Comparative Example 3

[0101] A method for preparing a CoCuOH / Co3O4 composite material, the preparation steps are the same as (1)-(3) in Example 1.

[0102] Comparative Example 4

[0103] A method for preparing CuO / Co3O4 composite material, the preparation steps are the same as (1)-(4) in Example 1.

[0104] Comparative Example 5

[0105] A method for preparing Cu2O / Co3O4 composite material, the preparation steps are the same as (1)-(5) in Example 1.

[0106] Comparative Example 6

[0107] A Co x The preparation method of O material is the same as in Example 1, except that copper nitrate trihydrate is not added in step (2). The specific preparation process is as follows:

[0108] (1) Pretreatment of foamed nickel: Cut commercial foamed nickel into 1.5 cm × 3 cm pieces, and then ultrasonically wash them in 0.5 mol / L sulfuric acid solution, deionized water and ethanol for 15 minutes each. Rinse them with deionized water and let them air dry for later use.

[0109] (2) Preparation of reaction solution: Weigh 2.5 mmol urea, 2.0 mmol ammonium fluoride and 1.25 mmol cobalt nitrate hexahydrate and add them to 40 mL of deionized water solution. Stir for 30 minutes to obtain a homogeneous solution.

[0110] (3) Hydrothermal reaction: The cleaned nickel foam from step (1) is placed in the homogeneous solution prepared in step (2), placed in a reaction vessel, and then kept in an oven at 140 °C for 8 hours. After the reaction is completed, it is naturally cooled to room temperature, the synthesized product is rinsed with deionized water, and then placed in an oven at 60 °C for 3 hours to obtain the product.

[0111] (4) Heat treatment reaction: The product obtained in step (3) is placed in a tube furnace and heated at 5 °C·min under a N2 atmosphere. -1 The product was obtained by heating to 400 °C at a heating rate of 3 h and then naturally cooling to room temperature.

[0112] (5) Phytic acid etching and soaking reaction: The product obtained in step (4) was immersed in phytic acid solution for 5 hours for etching, then thoroughly rinsed with deionized water and ethanol, and then vacuum dried at 60°C for 6 hours to obtain the product;

[0113] (6) Sodium borohydride reduction reaction: The product obtained in step (5) was placed in an aqueous solution of sodium borohydride and soaked for 10 h for reduction treatment. Then it was thoroughly rinsed with deionized water and ethanol in sequence, and then vacuum dried at 60 °C for 6 h to finally obtain the target electrocatalyst-Co. x O material.

[0114] Comparative Example 7

[0115] A method for preparing Cu2O material is the same as in Example 1, except that cobalt nitrate hexahydrate is not added in step (2). The specific preparation process is as follows:

[0116] (1) Pretreatment of nickel foam: Same as in Example 1;

[0117] (2) Preparation of reaction solution: Weigh 2.5 mmol urea, 2.0 mmol ammonium fluoride and 0.6 mmol copper nitrate trihydrate and add them to 40 mL of deionized water solution. Stir for 30 minutes to obtain a homogeneous solution.

[0118] (3) Hydrothermal reaction: The cleaned nickel foam from step (1) is placed in the homogeneous solution prepared in step (2), placed in a reaction vessel, and then kept in an oven at 140 °C for 12 h. After the reaction is completed, it is naturally cooled to room temperature, the synthesized product is rinsed with deionized water, and then placed in an oven at 60 °C for 3 h to obtain the product.

[0119] (4) Heat treatment reaction: The product obtained in step (3) is placed in a tube furnace and heated at 5 °C·min under a N2 atmosphere. -1 The product was obtained by heating to 400 °C at a heating rate of 3 h and then naturally cooling to room temperature.

[0120] (5) Phytic acid etching and soaking reaction: The product obtained in step (4) was soaked and etched in phytic acid solution for 5 hours, then rinsed thoroughly with deionized water and ethanol in sequence, and then vacuum dried at 60°C for 6 hours to obtain the product;

[0121] (6) Sodium borohydride reduction reaction: The product obtained in step (5) was placed in an aqueous solution of sodium borohydride and soaked for 10 h for reduction treatment. Then it was thoroughly rinsed with deionized water and ethanol, and then vacuum dried at 60 °C for 6 h to finally obtain the target electrocatalyst - Cu2O material.

[0122] Comparative Example 8

[0123] Same as Example 1, except that the reaction time is 3 hours when immersing and etching with phytic acid solution in step (5).

[0124] Comparative Example 9

[0125] Same as Example 1, except that the reaction time is 7 hours when immersing and etching with phytic acid solution in step (5).

[0126] Comparative Example 10

[0127] Same as Example 1, except that the reaction time is 9 hours when immersing and etching with phytic acid solution in step (5).

[0128] Comparative Example 11

[0129] Same as Example 1, except that the temperature of the hydrothermal reaction in step (3) is 100 °C.

[0130] Comparative Example 12

[0131] Same as Example 1, except that the temperature of the hydrothermal reaction in step (3) is 120 °C.

[0132] Comparative Example 13

[0133] Same as Example 1, except that the temperature of the hydrothermal reaction in step (3) is 160 °C.

[0134] Comparative Example 14

[0135] Same as Example 1, except that the temperature of the hydrothermal reaction in step (3) is 180 °C.

[0136] Morphological characterization and effect verification:

[0137] 1. Structure, composition, and morphological characteristics

[0138] Figure 1 The cobalt-copper based oxygen evolution electrocatalyst Cu2O / Co prepared in Example 1 of this invention xThe X-ray powder diffraction pattern of the O composite material, by Figure 1 It can be seen that the Cu2O / Co prepared in Example 1 x O composite material contains Cu2O and Co x O is a typical characteristic peak of X-ray powder diffraction.

[0139] Figure 2 The X-ray powder diffraction patterns of the CoCuOH / Co3O4 composite material, CuO / Co3O4 composite material, and Cu2O / Co3O4 composite material prepared in Example 1 show that the target product was successfully prepared in all cases.

[0140] Figure 3 Co prepared for Comparative Example 6 x The X-ray powder diffraction patterns of the O material and the Cu2O material prepared in Comparative Example 7 show that the target product was successfully prepared in both cases.

[0141] Figure 4 Image a shows scanning electron microscope (SEM) images of the CoCuOH / Co3O4 composite material, CuO / Co3O4 composite material, and Cu2O / Co3O4 composite material prepared in Example 1, respectively. Image b shows a scanning electron microscope (SEM) image of the Cu2O / Co3O4 composite material prepared in Example 1. x Scanning electron microscope image of the O composite material. From Figure 4 As can be seen from Figure a, the CoCuOH / Co3O4 composite material, CuO / Co3O4 composite material, and Cu2O / Co3O4 composite material all exhibit nanoflower morphology. From... Figure 4 As can be seen from Figure b, the morphology of the final target product obtained after a series of reactions remains unchanged, still exhibiting a nanoflower morphology. This indicates that the series of reactions did not affect the morphology of the material.

[0142] Figure 5 In Example 1, 'a' represents the Cu₂O / Co mixture prepared in this study. x Transmission electron microscopy (TEM) images of the O composite material further confirm the Cu2O / Co composition. x The O composite material has a nano-flower-like morphological structure; Figure 5 b represents the Cu2O / Co prepared in Example 1. x The high-resolution transmission electron microscope image of the O composite material confirms that its main crystal components are Cu2O, Co3O4 and CoO. Figure 5 c represents the Cu2O / Co prepared in Example 1. x The selected region electron diffraction (SAED) pattern of the O composite material shows clear diffraction rings on the (110), (200), and (331) planes of Cu2O, CoO, and Co3O4, and also reveals the Cu2O / Co composite material. x The elements in the O composite material are uniformly distributed; Figure 5In the middle, d represents the Cu2O / Co prepared in Example 1. x The selected region electron diffraction (SAED) pattern of the Cu2O / Co composite material shows that... x The lattice fringes of the O composite material correspond to the (110)(200) crystal plane of Cu2O, the (200) crystal plane of CoO, and the (331)(220) crystal plane of Co3O4.

[0143] Figure 6 In Example 1, 'a' represents the Cu₂O / Co mixture prepared in this study. x N2 adsorption / desorption isotherms and pore size distribution of the O composite material, b is the Co prepared in Comparative Example 6. x N2 adsorption / desorption isotherms and pore size distribution diagrams of the Cu2O material prepared in Comparative Example 7 are shown in diagram c. Figure 6 The Cu2O / Co ratio can be analyzed from the middle a. x The O composite material exhibits a typical Type III isotherm, with mesoporous characteristics and a significant hysteresis loop; from Figure 6 Co can be analyzed from b. x The O composite material exhibits a typical Type III isotherm, with mesoporous characteristics and a significant hysteresis loop; from Figure 6 Analysis of the middle part (c) reveals that the Cu2O composite material exhibits a typical Type III isotherm, with mesoporous characteristics and a significant hysteresis loop. From... Figure 6 From this, we can obtain Cu2O / Co x The O composite material has the largest BET surface area (91.76 m²). 2 ·g -1 This helps expose more active sites, promotes electrolyte diffusion, and improves gas emissions.

[0144] Figure 7 In Example 1, 'a' represents the Cu₂O / Co mixture prepared in this study. x O composite material, Co prepared in Comparative Example 6 x Electron paramagnetic resonance (EPR) spectra of the O material and the Cu2O material prepared in Comparative Example 7, b is the Cu2O / Co prepared in Example 1. x Electron paramagnetic resonance (EPR) spectra of the O composite material, the CoCuOH / Co3O4 composite material prepared in Comparative Example 3, the CuO / Co3O4 composite material prepared in Comparative Example 4, and the Cu2O / Co3O4 composite material prepared in Comparative Example 5. From... Figure 7It can be concluded that no obvious EPR signal was detected in the CoCuOH / Co3O4 composite material and the CuO / Co3O4 composite material (the EPR of both the CoCuOH / Co3O4 composite material and the CuO / Co3O4 composite material was zero, and the two overlapped). In contrast, after phytic acid treatment, the Cu2O / Co3O4 composite material showed a significant signal at g=2.30, which originated from the metal vacancies formed by phytic acid through complexation and extraction of metal ions. After further treatment with the strong reducing agent NaBH4, the target product Cu2O / Co x The O composite material exhibits a symmetrical and significantly enhanced signal at g=2.20. This signal enhancement indicates a substantial increase in defect density, originating from the reduction of surface metal ions and the accompanying lattice reconstruction, a process that generates and stabilizes metal vacancies. Comparative Examples 6 and 7 validate the defect characteristics: the Co prepared in Comparative Example 6... x The O material showed no signal, while the Cu2O material prepared in Comparative Example 7 showed only a weak signal at g=2.47, whereas the target product Cu2O / Co... x A significant feature of the O composite material was identified as copper vacancies. Target product Cu2O / Co x When O composite materials are used as catalysts, the moderate presence of copper defects is crucial for promoting electron transfer and enhancing reaction kinetics.

[0145] Figure 8 Cu2O / Co prepared in Example 1 x O composite material, Co prepared in Comparative Example 6 x Zeta potential diagrams of Cu₂O material prepared in 1.0 M KOH solution and Cu₂O material prepared in Comparative Example 7; the Zeta potentials measured in KOH solution show that the target product Cu₂O / Co x The O composite material has a more negative value (-25.3 mV) than its control group, and this enhanced surface negative charge indicates that the adsorbed OH groups in the inner Helmholtz layer... - The ion concentration is higher. This type of environment promotes efficient charge accumulation, thereby enhancing the activity of oxygen evolution reaction in alkaline media, highlighting the key role of surface charge regulation in catalytic enhancement.

[0146] Figure 9 Cu2O / Co prepared in Example 1 x O composite material, Co prepared in Comparative Example 6 x The contact angle diagrams of Cu₂O material and Cu₂O material prepared in Comparative Example 7 show that Cu₂O / Co x The small contact angle of the O-composite material confirms its good hydrophilicity. This hydrophilicity promotes close contact between the electrolyte and electrode and rapid electrolyte diffusion, enhances mass and charge transfer, and accelerates reaction kinetics.

[0147] Figure 10 Cu2O / Co prepared in Example 1 x O composite material, Co prepared in Comparative Example 6 x The cyclic voltammetry (CV) curves of Cu2O material and Cu2O material prepared in Comparative Example 7 show that, compared with the samples of Comparative Example 6 and Comparative Example 7, Cu2O / Co x The electrode oxidation peak potential of the O composite material exhibits a negative shift. This shift indicates a redistribution of interfacial electrons within the heterostructure, thereby enhancing the interaction with hydroxyl species (*OH). This optimized *OH adsorption behavior effectively lowers the energy barrier of the initial oxygen evolution reaction step, thus accelerating the surface reaction kinetics.

[0148] Figure 11 Cu2O / Co prepared in Example 1 x O composite material, Co prepared in Comparative Example 6 x X-ray photoelectron spectra of O material and Cu2O material prepared in Comparative Example 7; where a is the 2p spectrum of Co, b is the 2p spectrum of Cu, and c is the 1s spectrum of O. Figure 11 From a, we can see that Cu2O / Co x Co in O composite material 3+ / C 2+ The ratio (0.98) was significantly lower than that of Co. x Co in O composite material 3+ / C 2+ The ratio (2.33) indicates that the heterostructure induced Co 2+ Enrichment of this low-valence Co. 2+ The enrichment of [the substance] is crucial because it readily undergoes pre-oxidation during the oxygen evolution reaction to generate highly reactive Co. 3+ / Co 4+ This creates sites and simultaneously promotes the formation of active amorphous layers. This synergistic effect of creating abundant active sites and promoting charge transfer enhances reaction kinetics. Figure 11 As can be seen from b, compared with the Cu2O electrocatalyst composite material, quantitative analysis shows that Cu2O / Co x Cu in O composite material + The higher enrichment level directly confirms the enrichment effect induced by the heterostructure. This invention utilizes these abundant Cu... + Species act as electron donors, generating active Cu through in-situ pre-oxidation. 2+ / Cu 3+ Sites, while simultaneously regulating adjacent cobalt centers to promote Co 4+ This interfacial synergy promotes the formation of highly active reconstructed surfaces, thereby jointly accelerating the oxygen evolution reaction kinetics. From... Figure 11As can be seen from the middle c, the high-resolution O 1s energy spectrum exhibits three peaks, namely 529.48, 530.86 and 531.71 eV, corresponding to metal-oxygen (MO), metal-hydroxyl (M-OH) and adsorbed water molecules (H2O), respectively. ads ).

[0149] 2. The electrochemical test results are as follows:

[0150] Figure 12 This diagram illustrates the electrochemical performance test results of the electrocatalysts prepared in Examples 1 and Comparative Examples 2-7 in 1.0 M KOH solution for oxygen evolution. In the diagram, a is the linear scan curve of the electrocatalytic oxygen evolution reaction; b is the overpotential curve at different current densities; c is the Tafel slope diagram; d is the double-layer capacitance diagram; and e is the Cu₂O / Co electrocatalyst prepared in Example 1. x Bode phase diagrams of the O composite material at different potentials, f is the Cu2O / Co prepared in Example 1. x O composite material, Co prepared in Comparative Example 6 x A comparison of the phase angle versus application potential for different catalysts of O material and Cu2O material prepared in Comparative Example 7; g is the Cu2O / Co prepared in Example 1. x O composite materials and existing OER catalysts (see Table 1 for details) at 100 mA·cm⁻¹ -2 A comparison of overpotential and Tafel slope; h represents the Cu2O / Co prepared in Example 1. x O composite material at 100 mA·cm -2 The following is a graph showing the results of the three-electrode stability test. Figure 12 As can be seen from the above, the Cu2O / Co prepared in Example 1 x O-composite materials exhibit excellent electrochemical oxygen evolution performance and rapid charge transfer rates. (From...) Figure 12 The three-electrode stability of h is known to be at -10 mA·cm -2 Under these conditions, the overpotential hardly increased after 450 hours of continuous operation, further demonstrating its superior stability. Figure 12 The illustrations for h in the middle are Cu2O / Co x The scanning electron microscope (SEM) images of the O composite material after stability testing and the performance comparison before and after 1000 consecutive cyclic voltammetric scans show that its electrochemical performance did not decrease significantly after 1000 consecutive cyclic voltammetric scans. In addition, the morphology after stability testing maintained its structure, confirming the structural robustness of the catalyst. The SEM images after the test showed only slight agglomeration.

[0151] Table 1

[0152]

[0153] Figure 13 Co prepared for Comparative Example 6 x Bode phase diagrams of O material and Cu2O material prepared in Comparative Example 7 at different potentials; by comparison Figure 12 f and Figure 13 It can be concluded that Cu2O / Co x The frequency peak of the O composite material shifts to higher frequencies significantly faster with increasing potential than that of the control sample (Co). x (O materials and Cu2O materials). This rapid shift indicates that oxygen intermediates have easier adsorption and desorption characteristics during oxygen electrolysis. The overall results show that Co... x The synergistic integration of O and Cu2O accelerates electron transfer at the electrolyte-catalyst interface, thereby achieving excellent oxygen electrolysis kinetics performance.

[0154] Figure 14 The graphs show the electrochemical oxygen evolution performance of the materials prepared in Examples 1 and Comparative Examples 8-10 as electrocatalysts, where a is the linear scan curve of electrocatalytic oxygen evolution; b is the Tafel slope diagram; c is the double-layer capacitance diagram; and d is the electrochemical impedance spectroscopy. According to... Figure 14 It can be concluded that when the etching is performed by immersion in phytic acid solution for 5 hours, the electrochemical performance is optimal, the Tafel slope is lowest, the electrochemical impedance is smallest, and the double-layer capacitance is largest.

[0155] Figure 15 The graphs show the electrochemical performance (oxygen evolution) of the materials prepared in Examples 1 and Comparative Examples 11-14 as electrocatalysts, where a is the linear scan curve of the electrocatalytic oxygen evolution; b is the Tafel slope plot; c is the double-layer capacitance plot; and d is the electrochemical impedance spectroscopy. Figure 15 It can be concluded that when the hydrothermal reaction temperature is 140℃ and the time is 8h, the prepared composite material has the best electrochemical performance, the lowest Tafel slope, the smallest electrochemical impedance, and the largest bilayer capacitance.

[0156] Figure 16 Cu2O / Co prepared in Example 1 x Schematic diagram of the complete water decomposition process and results of Cu2O / Co composite material, where a is a schematic diagram of complete water decomposition; b is the test results of two electrodes, with an inset showing the comparison of electrode performance; c is the Cu2O / Co composite material prepared in Example 1. x Faraday test diagram of O composite material; d is Cu2O / Co prepared in Example 1. x A comparison of the voltage of the two-electrode system composed of O composite material with that of the full water splitting cell reported in the prior art using oxygen evolution electrocatalysts (see Table 2 for specific sources); e represents the Cu2O / Co prepared in Example 1. x The two-electrode system composed of O composite material performs total water splitting at 100 mA-2 Stability test results at time; f represents the Cu2O / Co prepared in Example 1. x Application of O-composite materials in total water decomposition in solar and wind power cells. Figure 16 As can be seen from ad, the Cu2O / Co prepared in this invention x A two-electrode system composed of O composite material and Pt / C exhibits excellent overall water splitting performance, superior to that of a two-electrode system composed of Pt / C and RuO2, and also superior to most water splitting catalysts reported in the prior art. Figure 16 From e, we can see that Cu2O / Co x A two-electrode system consisting of O composite material and RuO2 electrodes was tested at 100 mA·cm⁻¹. -2 It can operate stably for 560 hours, which also demonstrates the effectiveness of the Cu2O / Co prepared in this invention. x O composite materials exhibit good stability and durability when used as oxygen evolution electrocatalysts.

[0157] Table 2

[0158]

[0159] 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 cobalt-copper-based oxygen evolution electrocatalyst, characterized in that, Includes the following steps: Pretreated nickel foam was added to an aqueous solution containing cobalt and copper sources, and a hydrothermal reaction was carried out at 140°C to prepare a CoCuOH / Co3O4 composite material. The CoCuOH / Co3O4 composite material was subjected to heat treatment and then cooled to obtain CuO / Co3O4 composite material. The CuO / Co3O4 composite material was etched in phytic acid solution for 5 hours, followed by washing and drying to obtain Cu2O / Co3O4 composite material. Finally, the Cu2O / Co3O4 composite material was reduced with sodium borohydride solution to obtain Cu2O / Co x O composite material, namely Cu2O / Co x The O composite material is the cobalt-copper based oxygen evolution electrocatalyst, wherein Co x O is a complex of Co3O4 and CoO.

2. The method for preparing the cobalt-copper based oxygen evolution electrocatalyst according to claim 1, characterized in that, The pretreatment method for the nickel foam is as follows: cut the nickel foam into small pieces, then ultrasonically wash it in sulfuric acid solution, deionized water and ethanol in sequence, rinse it with deionized water and let it air dry.

3. The method for preparing the cobalt-copper based oxygen evolution electrocatalyst according to claim 1, characterized in that, The aqueous solution containing cobalt and copper sources is prepared by dissolving urea, ammonium fluoride, cobalt nitrate hexahydrate and copper nitrate trihydrate in water.

4. The method for preparing the cobalt-copper based oxygen evolution electrocatalyst according to claim 3, characterized in that, The molar ratio of urea, ammonium fluoride, cobalt nitrate hexahydrate, and copper nitrate trihydrate is 25:20:12.5:

6.

5. The method for preparing the cobalt-copper based oxygen evolution electrocatalyst according to claim 1, characterized in that, The hydrothermal reaction time is 12 h.

6. The method for preparing the cobalt-copper based oxygen evolution electrocatalyst according to claim 1, characterized in that, The heat treatment was carried out in an inert gas atmosphere at a temperature of 400°C for 3 hours, with a heating rate of 5°C / min. -1 .

7. The method for preparing the cobalt-copper based oxygen evolution electrocatalyst according to claim 1, characterized in that, The phytic acid solution is obtained by mixing phytic acid and ethanol in a volume ratio of 1:

1.

8. The method for preparing the cobalt-copper based oxygen evolution electrocatalyst according to claim 1, characterized in that, The concentration of the sodium borohydride solution is 0.5 wt%. And / or, the reduction process takes 10 hours.

9. A cobalt-copper based oxygen evolution electrocatalyst, characterized in that, It is prepared according to any one of claims 1-8.

10. The application of a cobalt-copper based oxygen evolution electrocatalyst as described in claim 9 in total water splitting, characterized in that, The cobalt-copper based oxygen evolution electrocatalyst serves as an oxygen evolution electrocatalyst.

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