Copper-based heterojunction catalyst for urea oxidation coupled hydrogen evolution reaction and preparation method and application thereof

Abstract

This invention relates to the field of electrocatalysts, specifically to a copper-based heterojunction catalyst for urea oxidation coupled with hydrogen evolution reaction, its preparation method, and its application. The catalyst comprises: a conductive substrate, a Cu(OH)₂ nanorod array, and NiCo layered double hydroxide nanosheets; the Cu(OH)₂ nanorod array is grown in situ on at least one surface of the conductive substrate; the NiCo layered double hydroxide nanosheets coat the surface of the Cu(OH)₂ nanorods. The preparation method includes providing and pretreating the conductive substrate; growing the Cu(OH)₂ nanorod array in situ on the surface of the conductive substrate by chemical oxidation; and growing the NiCo layered double hydroxide nanosheets in situ on the surface of the Cu(OH)₂ nanorods by hydrothermal methods, forming a core-shell heterostructure. This invention features a stable structure, controllable interface, and suitability for industrial-scale high current density applications, and can be used in urea oxidation reactions.

Description

Technical Field

[0001] This invention relates to the field of electrocatalyst technology, specifically to a copper-based heterojunction catalyst for urea oxidation coupled with hydrogen evolution reaction, its preparation method, and its application. Background Technology

[0002] With the escalating global energy crisis and the introduction of the "dual-carbon" strategic goal, developing clean and efficient renewable energy storage and conversion technologies has become an urgent priority. Hydrogen (H2), due to its extremely high energy density and zero carbon emissions, is considered an ideal carrier for future energy systems. Among various hydrogen production technologies, water electrolysis is highly mature, but its slow kinetics (large Tafel slope) and high thermodynamic barrier in the anodic oxygen evolution reaction (OER) result in persistently high overall energy consumption. Furthermore, the risk of cross-diffusion between anodic oxygen (O2) and cathode hydrogen (H2) poses safety hazards, limiting its large-scale application at high current densities.

[0003] To address the aforementioned issues, the strategy of using thermodynamically more readily occurring small-molecule oxidation reactions to replace OER (urea oxidation reaction) to reduce electrolyzer voltage has attracted considerable attention. Among these, the urea oxidation reaction (UOR) not only possesses a theoretical oxidation potential as low as 0.37V (vs. RHE), but it can also convert the chemical energy in urea-containing wastewater into hydrogen energy, achieving synergy between pollutant removal and clean energy production. However, UOR involves complex six-electron proton coupling and transfer processes, as well as the adsorption and desorption of various intermediates, resulting in slow intrinsic kinetics. In particular, the catalyst surface is prone to passivation or structural collapse during the reaction, leading to activity decay, which severely restricts the development of urea-assisted electrolysis hydrogen production technology.

[0004] Currently, researchers have developed various non-noble metal-based UOR catalysts, such as copper-based oxides, sulfides, and phosphides. Among them, copper-based materials have become a research hotspot due to their suitable adsorption energy for UOR intermediates. However, single-component copper-based catalysts are often limited by their semiconductor properties, exhibiting poor conductivity, and their active sites are mainly confined to the surface layer, making it difficult for deeper active materials to participate in the reaction. Furthermore, under long-term anodic oxidation potentials, the surface reconstruction of the catalyst is often uncontrollable, easily forming a thick oxide layer with low activity, leading to increased charge transport resistance and decreased stability. Studies have shown that by constructing heterostructures or performing interface doping, the electronic structure of the catalyst can be effectively tuned, and the d-band center position can be optimized, thereby reducing the energy barrier of rate-determining steps (such as dehydrogenation) in the UOR process and accelerating reaction kinetics. Therefore, designing a self-supporting electrode with strong electronic interactions, abundant active interfaces, and a stable structure through precise interface engineering is of great significance for improving the overall performance of urea-assisted hydrogen production. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings of the prior art and provide a copper-based heterojunction catalyst with stable catalytic activity, controllable interface, and suitable for industrial-grade high current density scenarios, for use in urea oxidation coupled with hydrogen evolution reaction, and its preparation method.

[0006] Another objective of this invention is to provide an application of the above-mentioned copper-based heterojunction catalyst in the simultaneous treatment of urea-containing wastewater and hydrogen production.

[0007] To solve the above-mentioned technical problems, the present invention is implemented as follows: A copper-based heterojunction catalyst for urea oxidation coupled with hydrogen evolution reaction comprises: a conductive substrate, a Cu(OH)2 nanorod array, and NiCo layered double hydroxide nanosheets; the Cu(OH)2 nanorod array is grown in situ on at least one surface of the conductive substrate; the NiCo layered double hydroxide nanosheets coat the surface of the Cu(OH)2 nanorods; a heterojunction interface is formed between the Cu(OH)2 nanorods and the NiCo layered double hydroxide nanosheets.

[0008] Furthermore, the conductive substrate is copper foam; the molar ratio of Ni to Co in the catalyst is 1 to 3:1.

[0009] The present invention also provides an application of the above-mentioned catalyst in the simultaneous treatment of urea-containing wastewater and hydrogen production.

[0010] The present invention also provides an electrolytic water hydrogen production apparatus, which includes a cathode, an anode and an electrolyte, wherein the cathode and / or the anode employs the above-mentioned catalyst.

[0011] A method for preparing the above-mentioned copper-based heterojunction catalyst for urea oxidation coupled with hydrogen evolution reaction, comprising: S1: Provide a conductive substrate and perform pretreatment; S2: Cu(OH)2 nanorod arrays are grown in situ on the surface of the conductive substrate by chemical oxidation; S3: NiCo layered double hydroxide nanosheets are grown in situ on the surface of Cu(OH)2 nanorods by hydrothermal method to form a core-shell heterostructure.

[0012] Further, in step S1, the conductive substrate is copper foam; in step S2, the solution used in the chemical oxidation method is an aqueous solution containing NaOH and (NH4)2S2O8.

[0013] Furthermore, in step S2, the chemical oxidation reaction time is 10–30 min.

[0014] Furthermore, in step S3, the hydrothermal reaction solution contains nickel salt, cobalt salt, and urea.

[0015] Furthermore, the nickel salt and cobalt salt are nitrates, chlorides, or sulfates.

[0016] Furthermore, in step S3, the reaction temperature of the hydrothermal method is 100-130°C, and the reaction time is 9-11 hours.

[0017] This invention addresses the key technical problems of low activity and poor stability of existing non-precious metal (especially copper-based) catalysts under industrial-grade high current densities. It proposes a core-shell heterojunction catalyst, "Cu(OH)₂ nanorods@NiCo-LDH nanosheets," constructed in situ using a two-step "chemical oxidation-hydrothermal" method on a copper foam substrate. The core of this invention lies in utilizing the heterojunction interface effect to induce directional charge migration, thereby optimizing the electronic structure of NiCo-LDH and enhancing its intrinsic catalytic activity. Simultaneously, the unique core-shell array structure provides a large specific surface area and structural stability, suppressing surface reconstruction and performance degradation of the catalyst under long-term anodic oxidation conditions. Ultimately, this achieves highly efficient and stable urea oxidation (UOR) and hydrogen evolution reaction (HER) at high current densities. In the above technical means, the core-shell heterojunction, interfacial charge migration, and the two-step in-situ growth steps are tightly integrated.

[0018] Compared with the prior art, the present invention has the following technical effects: (1) This invention achieves directional charge migration through the heterojunction effect between Cu(OH)2 and NiCo-LDH, optimizes the electronic structure, and enhances intrinsic catalytic activity. Data from the examples show that the UOR onset potential is significantly lower than the OER, and the current density at the same potential is much higher than that of the comparative example.

[0019] (2) The core-shell nanoarray structure of the present invention provides a high specific surface area and a fast material transport channel. Combined with the optimized electronic structure, it results in a smaller Tafel slope, a lower charge transfer resistance, and reaction kinetics that are significantly better than those of the prior art.

[0020] (3) The core-shell structure grown in situ in this invention exhibits good mechanical adhesion, and the NiCo-LDH nanosheets are effectively anchored by Cu(OH)2 nanorods, inhibiting aggregation and exfoliation. Simultaneously, the heterogeneous interface alleviates the irreversible reconstruction of the catalyst at the anodic potential. The catalyst, under high current density (1 A·cm⁻¹), exhibits good mechanical adhesion. -2 The fact that it has been running stably for more than 100 hours indicates that it has the potential for industrial applications.

[0021] (4) By using the catalyst of this invention simultaneously in the cathode (HER) and anode (UOR), efficient hydrogen production can be achieved at a lower cell pressure, while simultaneously treating urea-containing wastewater, thus realizing a synergy between energy conservation and environmental protection. This catalyst can not only be used for the degradation of urea in wastewater, but also has an energy-saving hydrogen production function, exhibiting good long-term stability under 0.33M urea conditions; moreover, it does not require the use of precious metals, is low in cost, and provides an integrated solution for sustainable energy development and environmental governance, showing significant potential for application in the field of energy catalysis.

[0022] (5) The synthesis method of this catalyst is simple. It optimizes the electronic structure of the active site by utilizing the electronic coupling effect between transition metals, promotes the surface dynamic reconstruction process, and endows it with rapid catalytic reaction kinetics, showing good prospects for industrial application.

[0023] (6) The catalyst prepared by the present invention exhibits excellent catalytic activity in the urea oxidation reaction, significantly reducing the overpotential compared with the traditional oxygen evolution reaction, and effectively improving the energy conversion efficiency. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating the preparation method of the copper-based heterojunction catalyst of the present invention. Figure 2 The voltage-current diagrams of the catalysts in Examples 1 to 3, Comparative Example 1, and Comparative Example 2 of this invention are shown in the LSV test. Figure 3 These are Tafle diagrams of the catalysts in Examples 1 to 3, Comparative Example 1, and Comparative Example 2 of the present invention; Figure 4 Impedance diagrams of the catalysts in Examples 1 to 3, Comparative Example 1, and Comparative Example 2 of the present invention in EIS. Figure 5 This is a comparison chart of the urea oxidation reaction performance and oxygen evolution reaction performance of the catalyst electrode material in Embodiment 1 of the present invention; Figure 6 C is the catalyst in Examples 1 to 3 of this invention. dl picture; Figure 7 This is a comparison chart of the reactive performance of the catalysts in Examples 1 to 3 of the present invention; Figure 8 XPS spectra of the metal elements of the catalysts in Example 3, Comparative Example 1, and Comparative Example 2 of this invention; Figure 9 This is a stability test diagram of the catalyst in Example 1 of the present invention for urea oxidation in an AEM electrolyzer at a current density of 1A. The catalyst voltage decayed by 0.19V after 200h. Detailed Implementation

[0025] The present invention will now be described in detail through specific embodiments. These embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art. As used throughout the specification and claims, the terms "comprising" or "including" are open-ended and are interpreted as "comprising but not limited to". The following description is a preferred embodiment for carrying out the invention; however, this description is intended to illustrate the general principles of the specification and is not intended to limit the scope of the invention. The scope of protection of the invention is determined by the appended claims. Unless otherwise specified, all reagents and materials used in the present invention are commercially available.

[0026] The method of the present invention for a copper-based heterojunction catalyst used in the urea oxidation coupled hydrogen evolution reaction specifically includes the following steps: 1. Substrate Pretreatment: The copper foam was sequentially ultrasonically cleaned with hydrochloric acid, anhydrous ethanol, and deionized water to remove surface oxides and impurities, and then vacuum dried to obtain substrate material A. Ultrasonic cleaning with hydrochloric acid effectively removes the oxide layer (CuO / Cu2O) on the surface of the copper foam, exposing the metallic copper substrate, which is beneficial for the uniform nucleation and growth of nanorods. Anhydrous ethanol and deionized water cleaning were used to remove organic residues.

[0027] 2. Chemical Oxidation Deposition: Substrate A was immersed in a mixed solution of NaOH and (NH4)2S2O8 and reacted at room temperature for 15 min, resulting in the in-situ growth of Cu(OH)2 nanorod arrays on the surface of the copper foam, forming substrate B. NaOH was used to provide an alkaline environment, and (NH4)2S2O8 was used as the oxidant. At room temperature, copper atoms on the surface of the copper foam were oxidized to Cu. 2+ The nanorods combine with OH⁻ to nucleate and grow in situ on the substrate as Cu(OH)₂ nanorod arrays. By controlling the reaction time to 15 min, the density, length, and diameter of the nanorods can be optimized, providing an ideal framework for subsequent NiCo-LDH coating.

[0028] 3. Hydrothermal Coating: Substrate B was placed in a hydrothermal solution containing Ni(NO3)2·6H2O, Co(NO3)2·6H2O, and urea, and reacted at 120℃ for 10 h. NiCo-LDH nanosheets were coated onto the Cu(OH)2 surface, forming a core-shell heterostructure. Under hydrothermal conditions, urea decomposes to produce OH-. - With CO2, the pH of the solution is slowly increased, promoting Ni 2+ and Co 2+Co-precipitation and nucleation on the surface of Cu(OH)₂ nanorods. Due to the abundant hydroxyl functional groups on the Cu(OH)₂ surface, there is a strong interaction with the NiCo-LDH precursor, driving the selective and uniform growth of NiCo-LDH nanosheets on the Cu(OH)₂ surface, rather than self-nucleation to form aggregates. This ultimately results in a robust core-shell heterostructure. More importantly, due to the difference in work function between the two at the heterostructure interface, electrons spontaneously migrate from the higher Fermi level to the lower level, generating an internal electric field. This rearrangement of the electronic structure optimizes the adsorption energy of intermediates (such as urea molecules and their decomposition products) on the NiCo-LDH surface, thereby significantly enhancing the intrinsic activity and reaction kinetics of UOR.

[0029] Example 1

[0030] S1: Preparation of substrate material A Commercially available copper foam (cut to size 1.5cm × 3cm × 1mm) was immersed in 3M hydrochloric acid and ultrasonically cleaned for 15 minutes. Then, the copper foam was ultrasonically treated by immersing it in anhydrous ethanol and deionized water to remove copper oxide and other stains from its surface. After removal, the copper foam was placed in a vacuum drying oven and dried at 60°C for 12 hours to remove excess moisture.

[0031] S2: Preparation of substrate material B A 10 mol / L sodium hydroxide solution and a 0.182 mol / L ammonium persulfate solution were prepared. Specifically, 80 mmol (3.2 g) of sodium hydroxide was dissolved in 8 mL of deionized water and stirred until homogeneous. 4 mmol (0.913 g) of ammonium persulfate was dissolved in 22 mL of deionized water and stirred until homogeneous. The prepared sodium hydroxide solution was then slowly added dropwise to the ammonium persulfate solution, and the mixture was stirred thoroughly until homogeneous. The substrate material A from S1 was placed in the above mixture and immersed thoroughly at room temperature for 15 minutes to allow for in-situ chemical oxidation precipitation. The precipitate was then quickly removed, repeatedly rinsed with deionized water, and vacuum dried at 60 °C to obtain substrate material B--Cu(OH)2.

[0032] S3: Catalyst Preparation 1.5 mmol (0.436 g) of nickel nitrate hexahydrate and 0.5 mmol (0.146 g) of cobalt nitrate hexahydrate were weighed and dissolved in 45 mL of deionized water, and stirred until homogeneous. 4.5 mmol (0.273 g) of urea was weighed and added to the above nickel nitrate and cobalt nitrate solution, and stirred thoroughly for 30 min to obtain a hydrothermal reaction solution with a Ni:Co molar ratio of 3:1. The hydrothermal solution was transferred to a 50 mL reactor liner, and substrate material B was added for hydrothermal treatment. The hydrothermal temperature was 120 °C, and the hydrothermal time was 10 h. After the reactor had completely cooled, the material was removed, rinsed repeatedly with anhydrous ethanol and deionized water, and then placed in a vacuum drying oven at 60 °C for 12 h to obtain the catalyst.

[0033] Example 2

[0034] S1: Preparation of substrate material A Commercially available copper foam (cut to size 1.5cm × 3cm × 1mm) was immersed in 3M hydrochloric acid and ultrasonically cleaned for 15 minutes. Then, the copper foam was ultrasonically treated by immersing it in anhydrous ethanol and deionized water to remove copper oxide and other stains from its surface. After removal, the copper foam was placed in a vacuum drying oven and dried at 60°C for 12 hours to remove excess moisture.

[0035] S2: Preparation of substrate material B A 10 mol / L sodium hydroxide solution and a 0.182 mol / L ammonium persulfate solution were prepared. Specifically, 80 mmol (3.2 g) of sodium hydroxide was dissolved in 8 mL of deionized water and stirred until homogeneous. 4 mmol (0.913 g) of ammonium persulfate was dissolved in 22 mL of deionized water and stirred until homogeneous. The prepared sodium hydroxide solution was then slowly added dropwise to the ammonium persulfate solution, and the mixture was stirred thoroughly until homogeneous. The substrate material A from S1 was placed in the above mixture and immersed thoroughly at room temperature for 10 minutes to allow for in-situ chemical oxidation precipitation. The precipitate was then quickly removed, repeatedly rinsed with deionized water, and vacuum dried at 60 °C to obtain substrate material B--Cu(OH)2.

[0036] S3: Catalyst Preparation 1.5 mmol (0.436 g) of nickel nitrate hexahydrate and 0.5 mmol (0.146 g) of cobalt nitrate hexahydrate were weighed and dissolved in 45 mL of deionized water, and stirred until homogeneous. 4.5 mmol (0.273 g) of urea was weighed and added to the above nickel nitrate and cobalt nitrate solution, and stirred thoroughly for 30 min to obtain a hydrothermal reaction solution with a Ni:Co molar ratio of 3:1. The above hydrothermal solution was transferred to a 50 mL reactor liner, and substrate material B was added for hydrothermal treatment. The hydrothermal temperature was 120 °C, and the hydrothermal time was 10 h. After the reactor had completely cooled, the material was removed, rinsed repeatedly with anhydrous ethanol and deionized water, and then placed in a vacuum drying oven at 60 °C for 12 h to obtain the catalyst.

[0037] Example 3

[0038] S1: Preparation of substrate material A Commercially available copper foam (cut to size 1.5cm × 3cm × 1mm) was immersed in 3M hydrochloric acid and ultrasonically cleaned for 15 minutes. Then, the copper foam was ultrasonically treated by immersing it in anhydrous ethanol and deionized water to remove copper oxide and other stains from its surface. After removal, the copper foam was placed in a vacuum drying oven and dried at 60°C for 12 hours to remove excess moisture.

[0039] S2: Preparation of substrate material B A 10 mol / L sodium hydroxide solution and a 0.182 mol / L ammonium persulfate solution were prepared. Specifically, 80 mmol (3.2 g) of sodium hydroxide was dissolved in 8 mL of deionized water and stirred until homogeneous. 4 mmol (0.913 g) of ammonium persulfate was dissolved in 22 mL of deionized water and stirred until homogeneous. The prepared sodium hydroxide solution was then slowly added dropwise to the ammonium persulfate solution, and the mixture was stirred thoroughly until homogeneous. The substrate material A from S1 was placed in the above mixture and immersed thoroughly at room temperature for 30 minutes to allow for in-situ chemical oxidation precipitation. The precipitate was then quickly removed, repeatedly rinsed with deionized water, and vacuum dried at 60 °C to obtain substrate material B--Cu(OH)2.

[0040] S3: Catalyst Preparation 1.5 mmol (0.436 g) of nickel nitrate hexahydrate and 0.5 mmol (0.146 g) of cobalt nitrate hexahydrate were weighed and dissolved in 45 mL of deionized water, and stirred until homogeneous. 4.5 mmol (0.273 g) of urea was weighed and added to the above nickel nitrate and cobalt nitrate solution, and stirred thoroughly for 30 min to obtain a hydrothermal reaction solution with a Ni:Co molar ratio of 3:1. The hydrothermal solution was transferred to a 50 mL reactor liner, and substrate material B was added for hydrothermal treatment. The hydrothermal temperature was 120 °C, and the hydrothermal time was 10 h. After the reactor had completely cooled, the material was removed, rinsed repeatedly with anhydrous ethanol and deionized water, and then placed in a vacuum drying oven at 60 °C for 12 h to obtain the catalyst.

[0041] Comparative Example 1 S1: Preparation of substrate material A Commercially available copper foam (cut to size 1.5cm × 3cm × 1mm) was immersed in 3M hydrochloric acid and ultrasonically cleaned for 15 minutes. Then, the copper foam was ultrasonically treated by immersing it in anhydrous ethanol and deionized water to remove copper oxide and other stains from its surface. After removal, the copper foam was placed in a vacuum drying oven and dried at 60°C for 12 hours to remove excess moisture.

[0042] S2: Preparation of substrate material B Dissolve 80 mmol (3.2 g) of sodium hydroxide in 8 mL of deionized water and stir until homogeneous. Dissolve 4 mmol (0.913 g) of ammonium persulfate in 22 mL of deionized water and stir until homogeneous. Then, slowly add the prepared sodium hydroxide solution dropwise to the ammonium persulfate solution and stir thoroughly until homogeneous. Place substrate material A from S1 into the above mixture and soak it for 15 min to allow for in-situ chemical oxidation precipitation. Then, quickly remove it, rinse repeatedly with deionized water, and vacuum dry at 60 °C to obtain substrate material B.

[0043] Comparative Example 2 S1: Preparation of substrate material A Commercially available copper foam (cut to size 1.5cm × 3cm × 1mm) was immersed in 3M hydrochloric acid and ultrasonically cleaned for 15 minutes. Then, the copper foam was ultrasonically treated by immersing it in anhydrous ethanol and deionized water to remove copper oxide and other stains from its surface. After removal, the copper foam was placed in a vacuum drying oven and dried at 60°C for 12 hours to remove excess moisture.

[0044] S2: Catalyst preparation Weigh 1.5 mmol (0.436 g) of nickel nitrate hexahydrate and 0.5 mmol (0.146 g) of cobalt nitrate hexahydrate and dissolve them in 45 mL of deionized water, stirring until homogeneous. Weigh 4.5 mmol (0.273 g) of urea and add it to the above nickel nitrate and cobalt nitrate solution, stirring thoroughly for 30 min to obtain a hydrothermal solution. Transfer the above hydrothermal solution to a 50 mL reactor liner and add substrate material A, then perform hydrothermal treatment. The hydrothermal temperature is 120 °C and the time is 10 h. After the reactor has completely cooled, remove the material, rinse repeatedly with anhydrous ethanol and deionized water, and then place it in a vacuum drying oven at 60 °C to obtain the catalyst.

[0045] Electrochemical tests of the above materials were all performed using an electrochemical workstation from Shanghai Chenhua Instrument Co., Ltd., model GHI660D. The test conditions were a three-electrode electrolytic cell, with the catalyst as the working electrode, the platinum sheet electrode as the counter electrode, and the saturated calomel electrode as the reference electrode. The electrolyte was a mixed solution of 1M KOH and 0.33M urea.

[0046] Stability testing was conducted using a Metrohm ATU85247 electrochemical workstation. FAB-PK-130 was selected as the anion exchange membrane. Both the cathode and anode used NiCo-LDH@Cu(OH)2 catalysts, with an electrode surface area of ​​1 cm². The electrodes were placed on either side of the anion exchange membrane to form an AEM electrolytic cell. The electrolyte was a mixed solution of 1 M KOH and 0.33 M urea, and the operating current was 1 A; the electrolyte was replaced every 12 hours.

[0047] The elemental composition and chemical bonding state of the material were analyzed using X-ray photoelectron spectroscopy (XPS). The instrument used (Axis Supra+, Shimadzu Corporation, UK) was equipped with an Al / Ag dual-anode X-ray source. All binding energies were calibrated with reference to the C 1s binding energy (284.8 eV).

[0048] The above embodiments are used to explain and illustrate the present invention, but not to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims fall within the protection scope of the present invention.

Claims

1. A copper-based heterojunction catalyst for urea oxidation coupled with hydrogen evolution reaction, characterized in that, include: A conductive substrate, a Cu(OH)2 nanorod array, and NiCo layered double hydroxide nanosheets are described. The Cu(OH)2 nanorod array is grown in situ on at least one surface of the conductive substrate. The NiCo layered double hydroxide nanosheets are coated on the surface of the Cu(OH)2 nanorods. A heterogeneous interface is formed between the Cu(OH)2 nanorods and the NiCo layered double hydroxide nanosheets.

2. The copper-based heterojunction catalyst for urea oxidation coupled with hydrogen evolution reaction according to claim 1, characterized in that, The conductive substrate is copper foam; the molar ratio of Ni to Co in the catalyst is 1 to 3:

1.

3. The application of the catalyst as described in claim 1 or 2 in the simultaneous treatment of urea-containing wastewater and hydrogen production.

4. A water electrolysis hydrogen production device, characterized in that, It includes a cathode, an anode, and an electrolyte, wherein the cathode and / or anode employs the catalyst as described in claim 1 or 2.

5. A method for preparing a copper-based heterojunction catalyst for urea oxidation coupled with hydrogen evolution reaction as described in claim 1, characterized in that, include: S1: Provide a conductive substrate and perform pretreatment; S2: Cu(OH)2 nanorod arrays are grown in situ on the surface of the conductive substrate by chemical oxidation; S3: NiCo layered double hydroxide nanosheets are grown in situ on the surface of Cu(OH)2 nanorods by hydrothermal method to form a core-shell heterostructure.

6. The method for using a copper-based heterojunction catalyst for urea oxidation coupled with hydrogen evolution reaction according to claim 5, characterized in that, In step S1, the conductive substrate is copper foam; in step S2, the solution used in the chemical oxidation method is an aqueous solution containing NaOH and (NH4)2S2O8.

7. The method for using a copper-based heterojunction catalyst for urea oxidation coupled with hydrogen evolution reaction according to claim 6, characterized in that, In step S2, the reaction time of the chemical oxidation method is 10 to 30 minutes.

8. The method for using a copper-based heterojunction catalyst for urea oxidation coupled with hydrogen evolution reaction according to claim 7, characterized in that, In step S3, the hydrothermal reaction solution contains nickel salt, cobalt salt, and urea.

9. The method for using a copper-based heterojunction catalyst for urea oxidation coupled with hydrogen evolution reaction according to claim 8, characterized in that, The nickel and cobalt salts are nitrates.

10. The method for using a copper-based heterojunction catalyst for urea oxidation coupled with hydrogen evolution reaction according to claim 9, characterized in that, In step S3, the hydrothermal reaction temperature is 120°C and the reaction time is 10 hours.

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