A method for preparing a modified Cu2O film based on an electrodeposition technique

Abstract

The application provides a preparation method of modified Cu2O thin films based on an electrodeposition technology and belongs to the technical field of photoelectrocatalytic materials. The application first prepares pure-phase Cu2O thin films with uniform crystal form and high crystallinity on an FTO transparent conductive substrate through a ligand-regulated electrodeposition process, then loads single-metal or multi-metal non-noble metal active sites on the surface of the Cu2O thin films through constant-potential / constant-current electrodeposition, and finally obtains modified Cu2O thin films. The whole process is carried out at normal temperature and pressure, the process is safe and environmentally friendly, batch consistency is good, production efficiency is high, and the process can be adapted to general electrode substrates of photoelectrocatalytic systems; the prepared thin films have high photo-generated carrier separation efficiency and are significantly inhibited in photo-corrosion, and in a photoelectrocatalytic carbon dioxide and nitrate co-reduction synthesis reaction of urea, the urea yield, selectivity and long-term stability are all greatly superior to those of the prior art.

Description

Technical Field

[0001] This invention belongs to the field of photoelectrocatalytic functional material preparation technology, specifically relating to a method for preparing modified Cu2O thin films based on electrodeposition technology. Background Technology

[0002] Urea is a core chemical in modern agriculture and the chemical industry. Current industrial production mainly uses the Bosch–Meiser process, which operates under high temperature and pressure, resulting in high energy consumption and large carbon emissions, accounting for 0.8% of global industrial carbon emissions annually, conflicting with carbon neutrality goals. Simultaneously, nitrate nitrogen pollution from industrial and agricultural wastewater is becoming increasingly serious. Traditional water treatment can only achieve nitrate neutralization, failing to recover nitrogen resources, creating a double challenge with the high pollution and high energy consumption of urea synthesis. The photoelectrocatalytic co-reduction synthesis of urea from carbon dioxide and nitrate can synthesize urea in one step at room temperature and pressure using CO2 as a carbon source and nitrate nitrogen as a nitrogen source, simultaneously achieving carbon sequestration, pollution control, and green urea production, becoming a research hotspot in the field of energy and environmental catalysis.

[0003] Cuprous oxide (Cu₂O) is a p-type semiconductor with a band gap of 1.9–2.2 eV. It can efficiently absorb visible light, and its conduction band bottom potential is suitable for nitrate reduction, CO₂ activation, and C₂ activation. N-coupling provides the thermodynamic driving force, and the surface Cu + The site can specifically adsorb intermediates, making it a preferred non-precious metal photocathode material for photoelectrocatalytic urea synthesis. Copper is abundant and inexpensive, and integrated thin-film electrodes can be prepared by electrodeposition, facilitating large-scale production. Existing methods for preparing Cu2O thin films mainly include hydrothermal synthesis, thermal oxidation, in-situ growth, and electrochemical deposition. Among these, hydrothermal and thermal oxidation methods are more widely used, but they have significant drawbacks. The hydrothermal method requires high temperature and pressure (100-200℃), with a reaction cycle of up to 20 hours, poor batch consistency, and can only form films on copper substrates, making it unsuitable for FTO transparent conductive substrates. Furthermore, it generates significant pollution from copper-containing waste liquid and exhaust gas. The thermal oxidation method requires the use of hydrogen, posing a high risk of combustion and explosion, and involves complex equipment, low production efficiency, and is difficult to scale up continuously.

[0004] Existing technologies for preparing pure-phase Cu₂O thin films have inherent drawbacks: insufficient surface active sites, weak CO₂ activation ability, insufficient active hydrogen supply, and low urea synthesis activity and selectivity; severe recombination of photogenerated carriers, resulting in low photoelectric conversion efficiency and high reaction energy consumption; and susceptibility to photocorrosion and Cu₂O degradation. + Disproportionation deactivation leads to poor long-term operational stability; the lack of multi-metal synergistic modification design results in performance that cannot meet industrialization requirements. Therefore, developing a modified Cu2O thin film preparation method that is safe and environmentally friendly, batch-stable, can be formed on FTO substrates, and can significantly improve catalytic activity and stability has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. To this end, the present invention provides a method for preparing modified Cu2O thin films based on electrodeposition technology, which solves the problems of poor batch consistency, low production safety, and poor process compatibility of traditional hydrothermal and thermal oxidation methods. At the same time, it breaks through the performance bottlenecks of low catalytic activity, poor selectivity, and insufficient stability of pure phase Cu2O, and meets the industrial application requirements of photoelectrocatalytic carbon-nitrogen coupling synthesis of urea.

[0006] The present invention also provides a modified Cu2O thin film electrode prepared by the above method.

[0007] A third aspect of the present invention provides the application of the above-mentioned modified Cu2O thin film electrode in photoelectrocatalytic urea synthesis, nitrate nitrogen wastewater resource utilization, and environmentally friendly anti-corrosion coatings.

[0008] The first aspect of the present invention provides a method for preparing modified Cu2O thin films based on electrodeposition technology, comprising the following steps: (1) Preparation of pure phase Cu2O thin film by electrodeposition: Prepare an electrodeposition solution containing Cu salt, ligand and pH buffer, adjust the pH to 9~12, and electrodeposit on FTO conductive glass with a three-electrode system using chronoamperometry to obtain pure phase Cu2O thin film; (2) Electrodeposition loading of non-precious metal active sites: Prepare an electrodeposition solution containing metal salt and complexing agent, use the Cu2O film obtained in step (1) as the working electrode, and use the constant potential method to electrodeposit to load single metal active sites or multi-metal active sites on the Cu2O surface to obtain modified Cu2O film.

[0009] One technical solution of the present invention concerning the preparation method of modified Cu2O thin films has at least the following beneficial effects: Pure-phase Cu2O thin films are prepared by electrodeposition on FTO conductive glass. The preparation can be completed at room temperature and pressure, without the need for high temperature, high pressure, or flammable and explosive reaction gas sources, making the production safe, environmentally friendly, and energy-efficient. It can be directly adapted to universal transparent conductive substrates for photoelectrocatalysis, with strong process compatibility, overcoming the shortcomings of traditional hydrothermal and thermal oxidation methods, which can only form films on copper substrates and cannot be used in photoelectrochemical systems.

[0010] The electrodeposition solution contains Cu salt, a ligand, and a pH buffer, with the pH adjusted to 9-12. Through precise synergistic control of the ligand and pH buffer, pure-phase Cu2O films with uniform crystal structure, high crystallinity, and regular morphology can be stably obtained, significantly improving batch consistency and repeatability, and enabling large-area, batch-scale stable preparation.

[0011] The three-electrode system combined with chronoamperometry electrodeposition allows for precise control of electrochemical parameters, enabling accurate control of film thickness, density, and crystal quality. The film exhibits strong adhesion to the substrate, low interfacial contact resistance, higher photogenerated carrier separation efficiency, and superior photoelectric response.

[0012] The second step involves electrodepositing non-noble metal single / multi-metal active sites to introduce highly dispersed active sites onto the Cu2O surface, enhancing CO2 activation, active hydrogen supply, and C2O activity. Directed coupling of N bonds simultaneously enhances the catalytic activity and selectivity of urea synthesis; metal sites can inhibit photocorrosion and Cu... + Disproportionation significantly extends the long-term operational stability of the electrode.

[0013] Both steps employ electrodeposition, forming a combined electrodeposition process. This process is simple, has mild conditions, is highly controllable, has high production efficiency, and is easy to scale up. It integrates preparation and functional modification, making it suitable for continuous industrial production and completely overcoming the bottlenecks of traditional methods such as batch variation, low efficiency, and poor stability.

[0014] According to some embodiments of the present invention, in step (1), the Cu salt includes at least one of CuSO4, Cu(NO3)2, and CuCl2.

[0015] According to some embodiments of the present invention, in step (1), the ligand includes D At least one of lactic acid, KH2PO4, hexadecyltrimethylammonium bromide, and polyvinylpyrrolidone.

[0016] According to some embodiments of the present invention, in step (1), the pH buffer factor includes at least one of KH2PO3, K2HPO3, and K2CO3.

[0017] According to some embodiments of the present invention, in step (1), the molar concentration ratio of the Cu salt, the ligand, and the pH buffer factor is 1:(10~14):(1~10).

[0018] According to some embodiments of the present invention, in step (1), the molar ratio of the Cu salt, the ligand, and the pH buffer factor is 1:10:1, 1:10:2, 1:10:3, 1:10:4, 1:10:5, 1:10:6, 1:10:7, 1:10:8, 1:10:9, 1:10:10, 1:11:1, 1:11:2, 1:11:3, 1:11:4, 1:11:5, 1:11:6, 1:11:7, 1:11:8, 1:11:9, 1:11:10, 1:12:1, 1:12:2, 1:12:3, 1:12:4, 1:12:5, 1: Any ratio from 12:6, 1:12:7, 1:12:8, 1:12:9, 1:12:10, 1:13:1, 1:13:2, 1:13:3, 1:13:4, 1:13:5, 1:13:6, 1:13:7, 1:13:8, 1:13:9, 1:13:10, 1:14:1, 1:14:2, 1:14:3, 1:14:4, 1:14:5, 1:14:6, 1:14:7, 1:14:8, 1:14:9, 1:14:10, such as 1:12:3, or any range of ratios formed by any three, such as 1:(10~12):(3~6).

[0019] According to some embodiments of the present invention, in step (1), the conditions for the chronoamperometry electrodeposition include: a temperature of 40~60℃, a stirring speed of 150~250rpm, and a cathode current density of 0.12~0.20mA·cm. -2 Deposition potential 0.7~ 1.0V, deposition time 3600~7200s.

[0020] According to some embodiments of the present invention, in step (2), the single metal active site includes at least one of Co, Bi, Ni, Sn, and Zn; and / or, the multi-metal active site is a combination of Co and Ni.

[0021] According to some embodiments of the present invention, in step (2), the molar ratio of metal salt to complexing agent in the electrodeposition solution containing metal salt and complexing agent is 1:(2~5).

[0022] According to some embodiments of the present invention, in step (2), the molar ratio of metal salt to complexing agent in the electrodeposition solution containing metal salt and complexing agent is any value of 1:2, 1:3, 1:4, 1:5, such as 1:2, or any range of the two, such as 1:2 to 1:4.

[0023] According to some embodiments of the present invention, in step (2), the molar ratio of Co salt, Ni salt and complexing agent in the electrodeposition solution of the multimetal is 1:1:(1~5).

[0024] According to some embodiments of the present invention, in step (2), the molar ratio of Co salt, Ni salt and complexing agent in the electrodeposition solution of the multimetal is any one of 1:1:1, 1:1:2, 1:1:3, 1:1:4, 1:1:5, such as 1:1:2, or any range of the three, such as 1:1:(2~4).

[0025] According to some embodiments of the present invention, the conditions for the constant potential electrodeposition method in step (2) include: stirring speed of 150~250 rpm and current density of 0.5 mA·cm. -2 The deposition time is 10~200s.

[0026] According to some embodiments of the present invention, after completing the chronoamperometry electrodeposition in step (1) and the constant potential electrodeposition in step (2), both electrodes are rinsed with ultrapure water and dried with nitrogen to obtain the finished electrode.

[0027] A second aspect of the present invention provides a modified Cu2O thin film electrode, which is prepared by the method of the first aspect of the present invention.

[0028] The modified Cu2O thin film electrode of the present invention, prepared by the aforementioned two-step electrodeposition method, has the following outstanding advantages: The electrode uses FTO transparent conductive glass as a substrate. The thin film has a regular crystal structure, high crystallinity, and uniform thickness, resulting in strong adhesion to the substrate, low interfacial contact resistance, and significantly improved photogenerated carrier separation and transport efficiency, leading to a stronger photoelectric response. Furthermore, the Cu2O surface is uniformly loaded with single-metal or multi-metal non-noble-metal active sites, which can enhance carbon dioxide activation, nitrate reduction, and C… Directed coupling of N-bonds significantly enhances the catalytic activity and selectivity of urea synthesis, surpassing that of pure-phase Cu2O electrodes. Furthermore, the metal-modified sites effectively inhibit Cu2O photocorrosion and Cu… + The electrode exhibits disproportionation deactivation, resulting in slow performance degradation during prolonged photoelectrocatalytic reactions and significantly superior operational stability compared to Cu2O electrodes prepared by hydrothermal and thermal oxidation methods. Furthermore, it can be deposited on a transparent FTO substrate, fully utilizing visible light and better meeting the optical and electrical requirements of photoelectrocatalytic systems, leading to higher actual catalytic efficiency. The thin-film electrode is prepared using an all-electrode deposition process, demonstrating high batch stability, large-area fabrication capability, and low cost, meeting the industrial application requirements for photoelectrocatalytic urea synthesis, wastewater resource recovery, and environmental corrosion prevention.

[0029] The third aspect of the present invention provides the application of the modified Cu2O thin film electrode of the second aspect of the present invention in urea synthesis, resource utilization treatment of nitrate nitrogen wastewater, and environmentally friendly anti-corrosion coatings.

[0030] When used in urea synthesis, it can achieve efficient co-reduction of carbon dioxide and nitrate under normal temperature and pressure, and directional C N-coupling significantly improves urea yield, selectivity, and photoelectric conversion efficiency compared to traditional pure-phase Cu2O electrodes, replacing the high-temperature, high-pressure Bosch–Meiser process. This greatly reduces energy consumption and carbon emissions, aligning with the needs of green, low-carbon synthesis and carbon neutrality and development.

[0031] When used for the resource recovery treatment of nitrate nitrogen wastewater, nitrate nitrogen in the wastewater can be used directly as the reaction nitrogen source, simultaneously achieving the degradation and removal of nitrate nitrogen pollutants and the high-value recovery of nitrogen resources. This avoids the shortcomings of traditional water treatment, which only renders the wastewater harmless but does not recover resources, reduces wastewater treatment costs and improves resource utilization, thus achieving both environmental and economic benefits.

[0032] When used in environmentally friendly anti-corrosion coatings, the film has high density and strong adhesion to the substrate. The loaded non-precious metal sites can optimize the surface electronic structure and chemical stability, significantly improving the resistance to photocorrosion, oxidation, and media erosion. It can be used as a multi-functional environmentally friendly anti-corrosion coating. It is non-toxic, harmless, and has good environmental compatibility, making it suitable for long-term protection of aquatic environments and optoelectronic equipment. Attached Figure Description

[0033] Figure 1 This is a flowchart of the method for electrodepositing and loading non-noble metal active sites.

[0034] Figure 2 These are SEM images of the surface morphology of different samples.

[0035] Figure 3 These are LSV curves under different light and dark contrasts for different samples.

[0036] Figure 4 This is a comparison chart of the urea synthesis rates of different samples.

[0037] Figure 5 This is a comparison of the sustained stability of urea synthesis from different samples at -0.22 V vs. RHE potential. Detailed Implementation

[0038] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0039] In a first aspect, in some embodiments of the present invention, the method for preparing pure-phase Cu2O thin films by electrodeposition may be: Preparation of electrodeposition solution: Cu salt, complexing agent and pH buffer are prepared in an appropriate amount of ultrapure water at a molar ratio of 1:(10~14):(1~10).

[0040] pH control: Stir the prepared electrodeposition solution at 25-35℃ and slowly adjust its pH to 9-12 using 3M KOH, then continue stirring for 10-12 h.

[0041] Assembly of the electrodeposition apparatus: A three-electrode system was used as the electrodeposition apparatus, and a pretreated area of ​​2 × 1.25 cm² was selected. 2 The working electrode is made of FTO conductive glass, and the counter electrode is made of platinum sheet, graphite rod electrode or copper sheet. The reference electrode is a Hg / HgO electrode filled with 1 mol / L KOH. The conductive surface of the working electrode is opposite to the counter electrode and faces the direction of rotation of the stirring rotor.

[0042] Experimental method for electrodeposition preparation of Cu₂O: The assembled electrodeposition apparatus was connected to an electrochemical workstation and placed in a water bath. The water bath temperature was controlled at 40–60 °C, and the rotor speed was 150–250 rpm during deposition. Chronopotentiometry (CP) was selected as the deposition mode, and the cathode current density was controlled at 0.12–0.20 mA·cm⁻¹. -2 The deposition potential is controlled between -0.7 and -1.0 V, and the deposition time is 3600~7200s.

[0043] Cu2O thin film post-treatment: After deposition, the sample is taken out, and the surface residual electrolyte is repeatedly rinsed with ultrapure water. After being dried with nitrogen, it is placed in a desiccator for later use, thus obtaining the Cu2O thin film electrode.

[0044] In a first aspect, in some embodiments of the present invention, the method for electrodepositing and loading non-noble metal active sites during metal deposition loading can be: Preparation of electrodeposition solution: Dissolve Co salt and complexing agent in an ultrapure aqueous solution at a ratio of 1:(2~5).

[0045] Assembly of the electrodeposition apparatus: A three-electrode system was used as the electrodeposition apparatus. The Cu₂O thin film electrode prepared in the above experiment was selected as the working electrode, a platinum sheet was selected as the counter electrode, and the reference electrode was an Ag / AgCl electrode filled with 0.1 mol / L KCl solution. The conductive surface of the working electrode was opposite to the counter electrode, and the conductive surface of the working electrode faced the direction of rotation of the stirring rotor.

[0046] Experimental method for electrodeposition of loaded single metals: The assembled electrodeposition apparatus was connected to an electrochemical workstation. During deposition, the rotor speed was 150–250 rpm. The deposition mode was selected as IT testing. The deposition current density was controlled to 0.5 mA·cm² through calculation and experimentation. -2 The deposition time is controlled between 10 and 200 seconds, depending on the load requirement.

[0047] Electrode post-treatment: After deposition, the sample is repeatedly rinsed with ultrapure water, dried with nitrogen, and then sealed and stored in a desiccator for later use.

[0048] In a first aspect, in some embodiments of the present invention, the method for electrodepositing non-noble metal active sites during multi-metal deposition loading can be: The electrolyte was prepared by dissolving Co salt, Ni salt, and complexing agent in an ultrapure aqueous solution at a ratio of 1:1:(1~5). The remaining experimental procedures were the same as for single-metal deposition loading. (See procedure reference.) Figure 1 As shown.

[0049] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0050] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0051] Unless otherwise specified, "room temperature" in this invention means 25℃±5℃.

[0052] Unless otherwise specified, "about" in this invention means that the allowable error is within ±2%.

[0053] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0054] Example 1 Cu2O thin film electrodes loaded with Co single metal sites were prepared.

[0055] To prepare pure-phase Cu₂O thin films, the electrodeposition solution was prepared using CuSO₄, D-lactic acid, and K₂HPO₃ in a molar ratio of 1:10:3. The pH was then adjusted to 12 with KOH, and the solution was continuously stirred for 12 h. After assembling the electrodeposition apparatus, the stirring speed was set to 200 rpm, and Cu₂O thin films were electrodeposited using a chronoamperometry method, with a current density controlled at 0.15 mA·cm⁻¹. -2 Deposition occurred at 40°C for 7200 s.

[0056] After post-treatment of the prepared Cu₂O, Co single-metal loading was further electrodeposited. The electrodeposition solution was prepared using cobalt nitrate and sodium citrate in a molar ratio of 1:2. Constant voltage electrodeposition was performed using the iterative method, with a stirring speed of 200 rpm and the current density controlled at 0.5 mA·cm⁻¹ by adjusting the potential. -2 The deposition time was 50 s. After deposition, the sample was post-processed and named Co. L -Cu2O.

[0057] Example 2 Cu2O thin film electrodes loaded with CoNi bimetallic sites were prepared.

[0058] For the preparation of pure-phase Cu₂O thin films, Cu(NO₃)₂, H₂PO₄, and K₂CO₃ were selected to prepare the electrodeposition solution in a molar ratio of 1:12:3. The pH was then adjusted to 10 with KOH, and the solution was continuously stirred for 12 h. After assembling the electrodeposition apparatus, the stirring speed was set to 150 rpm, and Cu₂O thin films were electrodeposited using a chronoamperometry method, with the current density controlled at 0.2 mA·cm⁻¹. -2 Deposition occurred at 60°C for 7200 s.

[0059] After post-treatment of the prepared Cu₂O, a CoNi bimetallic load was further electrodeposited. The electrodeposition solution was prepared using CoSO₄, NiSO₄, and sodium citrate in a molar ratio of 1:1:2. Constant voltage electrodeposition was performed using the iterative electrochemical method, with a stirring speed of 150 rpm and the current density controlled at 0.5 mA·cm⁻¹ by adjusting the potential. -2 The deposition time was 100 s. After deposition, the sample underwent post-processing and was named CoNi. H -Cu2O.

[0060] Figure 2These are SEM images of the surface morphology of different samples. (a) and (b) are pure-phase Cu2O at different magnifications; (c) is CoL-Cu2O; and (d) is CoNiH-Cu2O. It can be seen that the pure-phase Cu2O prepared by electrodeposition exhibits a highly crystalline, uniformly sized truncated octahedral crystal structure, proving that this process can achieve the preparation of dense films with controllable structure. After modification with Co single metal and CoNi bimetal, the substrate crystal structure remains intact, and the surface is uniformly loaded with highly dispersed nano-active sites.

[0061] Figure 3 The LSV curves show that the photocurrent density of pure phase Cu2O prepared by electrodeposition is improved compared with that of hydrothermal sample. The photocurrent is further improved after Co monometallic modification, while the photocurrent density of CoNi bimetallic modified sample reaches the optimum, which fully demonstrates the synergistic effect of Co site and Ni site.

[0062] Figure 4 The bar chart of urea yield shows that the yield of electrodeposited Cu2O is better than that of hydrothermal method, and the CoNi bimetallic modified sample has the highest yield and significantly improved activity at -0.22 V vs. RHE.

[0063] Figure 5 The I-T curves show that the current density of the CoNi-modified sample remained stable within 6 hours, effectively suppressing the photocorrosion of Cu2O and significantly improving the electrode stability.

[0064] As can be understood from the embodiments of this invention, compared with the best-performing hydrothermal and thermal oxidation methods in the prior art, this invention adopts a two-step all-electrode deposition process, which can be completed at room temperature and pressure, without the need for high-pressure containers and flammable and explosive hydrogen gas sources. The production process is safe and environmentally friendly, with no risks of high temperature and high pressure. It can directly form films on FTO transparent conductive substrates commonly used in photoelectrocatalysis, with strong process compatibility. Through precise control of ligands and electrochemical parameters, the crystal form, morphology, and thickness of pure-phase Cu2O films can be controlled, significantly improving batch consistency and repeatability, resulting in high production efficiency and enabling large-area, large-scale continuous production, fundamentally solving the core defects of existing processes. At the same time, this invention introduces a non-noble metal active site controllable deposition technology based on ligand regulation, which can achieve highly dispersed and uniform loading of single / multi-metal active sites on the Cu2O surface. Through the synergistic effect of bimetallic functions, it simultaneously solves the intrinsic performance bottlenecks of weak carbon dioxide activation ability and severe photocorrosion of pure-phase Cu2O, greatly improving the activity, selectivity, and long-term operational stability of photoelectrocatalytic carbon-nitrogen coupling synthesis of urea, providing a feasible technical solution for the industrial application of this technology.

[0065] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for preparing modified Cu2O thin films based on electrodeposition technology, characterized in that, Includes the following steps: (1) Preparation of pure phase Cu2O thin film by electrodeposition: Prepare an electrodeposition solution containing Cu salt, ligand and pH buffer, adjust the pH to 9~12, and electrodeposit on FTO conductive glass with a three-electrode system using chronoamperometry to obtain pure phase Cu2O thin film; (2) Electrodeposition loading of non-precious metal active sites: Prepare an electrodeposition solution containing metal salt and complexing agent, use the Cu2O film obtained in step (1) as the working electrode, and use the constant potential method to electrodeposit to load single metal active sites or multi-metal active sites on the Cu2O surface to obtain modified Cu2O film.

2. The preparation method according to claim 1, characterized in that, In step (1), the Cu salt includes at least one of CuSO4, Cu(NO3)2, and CuCl2; and / or, the ligand includes D At least one of lactic acid, KH2PO4, hexadecyltrimethylammonium bromide, and polyvinylpyrrolidone; and / or, the pH buffer factor includes at least one of KH2PO3, K2HPO3, and K2CO3.

3. The preparation method according to claim 1, characterized in that, In step (1), the molar concentration ratio of Cu salt, ligand and pH buffer factor is 1:(10~14):(1~10).

4. The preparation method according to claim 1, characterized in that, In step (1), the conditions for the chronoamperometry electrodeposition include: temperature 40~60℃, stirring speed 150~250rpm, and cathode current density 0.12~0.20mA·cm. -2 Deposition potential 0.7~ 1.0V, deposition time 3600~7200s.

5. The preparation method according to claim 1, characterized in that, In step (2), the single metal active site includes at least one of Co, Bi, Ni, Sn, and Zn; and / or, the multi-metal active site is a combination of Co and Ni.

6. The preparation method according to claim 1, characterized in that, In step (2), the molar ratio of metal salt to complexing agent in the electrodeposition solution containing metal salt and complexing agent is 1:(2~5); and / or, in step (2), the molar ratio of Co salt, Ni salt and complexing agent in the multi-metal electrodeposition solution is 1:1:(1~5).

7. The preparation method according to claim 1, characterized in that, The conditions for the constant potential electrodeposition method described in step (2) include: stirring speed of 150~250 rpm and current density of 0.5 mA·cm. -2 The deposition time is 10~200s.

8. The preparation method according to any one of claims 1 to 7, characterized in that, After completing the chronoamperometry electrodeposition in step (1) and the constant potential electrodeposition in step (2), both electrodes are rinsed with ultrapure water and dried with nitrogen to obtain the finished electrode.

9. A modified Cu₂O thin film electrode, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 7.

10. The application of the modified Cu2O thin film electrode according to claim 9 in urea synthesis, resource utilization treatment of nitrate nitrogen wastewater, and environmentally friendly anti-corrosion coating.

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