Preparation method and application of a rare earth doped copper oxide catalyst

Abstract

The application discloses a preparation method and application of a rare earth doped copper oxide catalyst, and belongs to the technical field of electrocatalysis. The preparation method comprises the following steps: first, polystyrene microspheres are prepared by using a soap-free emulsion polymerization method; then, a precursor solution is prepared; subsequently, the prepared polystyrene microspheres are added into the precursor solution, mixed and dried; finally, the obtained solid precursor is calcined to obtain a three-dimensional ordered porous structure rare earth doped copper-based catalyst. The catalyst is prepared into ink and dropped and coated on carbon paper to prepare a working electrode, and a higher urea yield of 94.46 mmol h ‑1 g catal. ‑1 at-1.5 V vs. RHE is achieved, and meanwhile, the electrode can still maintain a higher activity after being continuously operated for 110 h at the potential, thus exhibiting excellent stability and durability. The prepared catalyst has both a high urea generation rate and long-term operation stability, and has a good application prospect in the field of electrochemical C-N coupling to synthesize urea.

Description

Technical Field

[0001] This invention relates to the field of electrocatalysis technology, and in particular to a method for preparing rare earth-doped copper oxide catalyst and its application. Background Technology

[0002] Urea, as an indispensable nitrogen source in modern agriculture, plays a crucial strategic role in ensuring global food supply. Currently, industrial urea synthesis heavily relies on the thermochemical reaction of ammonia produced through the Haber-Bosch process with carbon dioxide under high temperature and pressure. This traditional route is extremely dependent on fossil fuels, with the ammonia synthesis stage accounting for approximately 2% of global primary energy consumption and accompanied by substantial carbon emissions. Furthermore, urea production consumes a significant proportion of global synthetic ammonia production, further exacerbating the dual pressures on energy and the environment. Against the backdrop of overlapping "dual carbon" goals and the energy crisis, there is an urgent need to develop novel urea synthesis technologies that are not reliant on fossil fuels, operate under milder conditions, and have high atom economy.

[0003] In recent years, the electrocatalytic CN-coupling synthesis of urea using renewable electricity to drive CO2 and nitrogen-containing small molecules (such as NO3⁻, NO2⁻, N2, etc.) has been considered one of the most promising green alternative routes because it can operate at ambient temperature and pressure and directly utilize renewable electricity. However, this electrocatalytic system still faces many fundamental challenges: the reaction process involves complex multi-step proton-coupled electron transfer (PCET) and the evolution of various C / N intermediates, and the key CN bond formation pathway and reaction mechanism have not been fully elucidated; at the same time, existing catalyst systems generally suffer from low active site density, insufficient adsorption selectivity for target intermediates, and poor long-term electrolytic stability, resulting in urea yield, Faradaic efficiency, and service life that are far from meeting the requirements of industrial applications. Summary of the Invention

[0004] To address the problems existing in the background technology, a method for preparing rare earth-doped copper oxide catalyst and its application are proposed. Using PS microspheres as templates, and after mixing with a precursor solution, a three-dimensional ordered porous rare earth-doped copper-based catalyst is constructed, providing an efficient solution for green electrosynthesis of urea.

[0005] This invention proposes a method for preparing a rare earth-doped copper oxide catalyst, comprising the following steps: firstly, preparing polystyrene microspheres using a soap-free emulsion polymerization method; then preparing a precursor solution; subsequently, adding the prepared polystyrene microspheres to the precursor solution, mixing, and drying; and finally calcining the obtained solid precursor to obtain a rare earth-doped copper-based catalyst with a three-dimensional ordered porous structure.

[0006] Preferably, the specific steps include:

[0007] S1. Styrene solution and polyvinylpyrrolidone solution are mixed, heated and stirred, and then potassium persulfate solution is added to obtain monodisperse colloidal polystyrene microsphere emulsion;

[0008] S2. After high-speed centrifugation, the supernatant of the monodisperse colloidal polystyrene microsphere emulsion is removed, and the white solid is dried to obtain polystyrene microspheres.

[0009] S3. Tm(NO3)3·5H2O and Cu(NO3)2·3H2O are completely dissolved in a solution of ethanol and water under continuous stirring at a certain molar ratio to obtain a precursor solution.

[0010] S4. Add polystyrene microspheres to the precursor solution, stir to obtain a suspension; dry the suspension to obtain a solid precursor.

[0011] S5. The solid precursor is calcined and cooled to room temperature to obtain a three-dimensional ordered porous rare earth-doped copper oxide catalyst.

[0012] Preferably, in step S1, an aqueous solution containing 0.1-2 g of polyvinylpyrrolidone is introduced into 13 mL of styrene; nitrogen gas is then introduced into the mixture for water bath heating and stirring; then an aqueous solution containing 0.2 g of potassium persulfate is added to initiate styrene polymerization; and stirring is continued to obtain a monodisperse colloidal polystyrene microsphere emulsion.

[0013] Preferably, the water bath heating and stirring temperature in S1 is 60-90℃, the stirring speed is 200-500 rpm, and the stirring time is 20-28 h.

[0014] Preferably, the centrifugation speed of the monodisperse colloidal polystyrene microsphere emulsion in S2 is 8000-10000 rpm, the centrifugation time is 20 min, and the drying temperature of the milky white solid obtained by centrifugation is 50-80℃, and the drying time is 12-18 h.

[0015] Preferably, the molar ratio of Tm(NO3)3·5H2O and Cu(NO3)2·3H2O in S3 is 1:10.

[0016] Preferably, the ratio of ethanol to water in S3 is 1:1.

[0017] Preferably, the mass ratio of polystyrene microspheres to precursor in S4 is 2:1, and after mixing, the mixture is placed in a vacuum oven for room temperature impregnation for 9-16 hours.

[0018] Preferably, the solid precursor in S5 is calcined in a muffle furnace as follows: first, the temperature is raised to 115°C at a heating rate of 5°C / min and held for 6 hours; then, the temperature is raised to 250°C at a heating rate of 5°C / min and held for 12 hours; next, the temperature is raised to 310°C and held for 2 hours; thereafter, the temperature is gradually raised to 310°C, 330°C, 350°C, 370°C and 400°C at a heating rate of 0.5°C / min, and held for 2.5 hours at each temperature point.

[0019] This invention further proposes an application of a rare earth-doped copper oxide catalyst, using the aforementioned rare earth-doped copper oxide catalyst for NO3. - In the process of CO2 electrocatalytic synthesis of urea.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] This invention utilizes polystyrene (PS) microspheres as a sacrificial template to construct a rare-earth-doped copper oxide catalyst with a three-dimensional ordered porous (3DOM) structure. This ordered pore structure features a regular arrangement, uniform pore size distribution (approximately 120 nm), and exhibits a multi-layered, continuous, interconnected network, significantly increasing the catalyst's specific surface area and providing ample active sites for reactant adsorption. Simultaneously, its three-dimensional interconnected framework structure is beneficial for the adsorption of reactants (CO2 and NO3). - The enrichment and rapid mass transfer diffusion on the electrode surface effectively reduce concentration polarization and improve the overall reaction kinetic efficiency.

[0022] This invention modifies the copper oxide lattice by introducing the rare earth element thulium (Tm), utilizing the 4f electron orbitals of Tm as an "electron compensation buffer band" to precisely control the local electronic structure on the catalyst surface. This appropriately optimizes the adsorption / desorption energy barrier for key reaction intermediates and effectively stabilizes Cu. 2＋ The active species significantly enhance the chemical stability and anti-sintering ability of the catalyst. Benefiting from the aforementioned structural and electronic synergistic effects, the optimal catalyst obtained is 3DOM-CuO-Tm. 0.1 Under ambient temperature and pressure conditions, it exhibits excellent electrocatalytic performance in CO2-saturated 0.01 M KNO3 and 0.3 M KHCO3 electrolytes: at a potential of -1.5 V (vs. RHE), the urea yield reaches as high as 94.46 mmol h⁻¹. -1 g catal. -1 Furthermore, during the continuous constant potential electrolysis process lasting up to 110 hours, the current density and yield showed no significant decay, demonstrating excellent long-term operational stability and providing an efficient and stable non-precious metal catalytic material solution for green electrosynthesis of urea. Attached Figure Description

[0023] Figure 1This is a schematic diagram of the preparation method of the rare earth-doped copper oxide catalyst in Example 1;

[0024] Figure 2 This is a scanning electron microscope image of the PS microspheres in Example 1;

[0025] Figure 3 It is 3DOM-CuO-Tm in Example 1 x X-ray diffraction spectrum;

[0026] Figure 4 It is 3DOM-CuO-Tm in Example 1 x X-ray photoelectron spectrum;

[0027] Figure 5 It is 3DOM-CuO-Tm in Example 1 0.1 Scanning electron microscope image;

[0028] Figure 6 It is 3DOM-CuO-Tm in Example 1 0.1 Transmission electron microscope image;

[0029] Figure 7 It is 3DOM-CuO-Tm in Example 1 0.1 EDX spectrum;

[0030] Figure 8 It is 3DOM-CuO-Tm in Example 2 0.1 A physical image of the apparatus used as the working electrode for the electrocatalytic synthesis of urea;

[0031] Figure 9 The 3DOM-CuO-Tm example in Example 2 is shown. 0.1 Linear current-voltage (LSV) curves under different electrolysis environments;

[0032] Figure 10 The diagram shows the detection results of ammonia content in Example 3, where (a) is the UV-Vis absorption spectrum of NH4Cl standard solutions of different concentrations; and (b) is the linear relationship between the light absorbance at 655 nm wavelength and the concentration of NH4Cl standard solution.

[0033] Figure 11 It is 3DOM-CuO-Tm in Example 3 0.1 Yield diagram of urea electrocatalytic synthesis as the working electrode;

[0034] Figure 12 It is 3DOM-CuO-Tm in Example 3 0.1 Faraday efficiency diagram for electrocatalytic synthesis of urea using the working electrode;

[0035] Figure 13 This refers to 3DOM-CuO-Tm under different Tm doping ratios in Example 3. x Catalytic urea yield graph;

[0036] Figure 14 It is 3DOM-CuO-Tm in Example 3 x The stability test results are shown in the figure. Detailed Implementation

[0037] Example 1, as Figure 1 As shown, this invention proposes a method for preparing a rare earth-doped copper oxide catalyst, the steps of which are as follows:

[0038] (1) Preparation of polystyrene template

[0039] 13 mL of styrene was washed with 4 mL of sodium hydroxide aqueous solution (10 wt%), followed by removal of the stabilizer with deionized water. The washed styrene was added to a 250 mL three-necked round-bottom flask, and then 100 mL of an aqueous solution containing 0.5 g of polyvinylpyrrolidone (PVP) was introduced. The mixture was bubbled with nitrogen for 15 minutes, and then magnetically stirred at 75 °C for 30 minutes. Immediately afterwards, 10 mL of an aqueous solution containing 0.2 g of potassium persulfate (K2S2O8) was added to the flask to initiate the polymerization of styrene. The mixture was continuously stirred at this temperature (speed <500 rpm) for 24 hours. After cooling, the resulting milky white product was the monodisperse colloidal polystyrene spheres. Figure 2 ).

[0040] Monodisperse polymethyl methacrylate microsphere emulsion was placed in centrifuge tubes and centrifuged at 10,000 r / min for 20 min. A milky white solid was obtained by centrifugation, and then dried to obtain a polystyrene (PS) template. The drying temperature was 50–80℃, and the drying time was 12–18 h.

[0041] (2) Preparation of 3DOM-CuO-Tm x catalyst

[0042] The resulting sol, using polystyrene (PS) spheres as templates, self-assembled into a three-dimensional ordered microporous (3DOM) array at room temperature. A typical procedure involved dispersing 0.625 mmol of copper nitrate trihydrate (Cu(NO3)2·3H2O) and 0.0625 mmol of thulium nitrate pentahydrate (Tm(NO3)3·5H2O) in 5 mL of a 1:1 ethanol-water solution. Subsequently, 0.36 g of the pre-prepared PS template was immersed in this precursor solution and placed in a vacuum oven for 9–16 minutes at room temperature. The resulting composite was calcined in air to remove the PS template. The heating program was as follows: the temperature was raised to 115℃ (heating rate 5℃ / min) and held for 6 hours, then raised to 250℃ (heating rate 5℃ / min) and held for 12 hours; next, the temperature was raised to 310℃ and held for 2 hours; thereafter, the temperature was gradually raised to 310℃, 330℃, 350℃, 370℃ and 400℃ at a heating rate of 0.5℃ / min, and held for 2.5 hours at each temperature. By adjusting the amount of thulium nitrate pentahydrate to 0.03125 mmol, 0.0625 mmol and 0.09375 mmol, a series of samples with Tm / Cu molar ratios of 5%, 10% and 15% were prepared, respectively.

[0043] Using X-ray diffraction (XRD), based on Figure 3 XRD analysis revealed that rare-earth doping did not alter the phase structure of copper oxide, and no corresponding diffraction peak for Tm was detected. The peak intensity of copper oxide decreased with increasing Tm content. X-ray photoelectron spectroscopy (XPS) characterized 3DOM-CuO-Tm. x Crystal structure and valence state, such as Figure 4 The XPS results shown indicate that 3DOM-CuO-Tm x The copper in it has a +2 oxidation state. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine 3DOM-CuO-Tm. 0.1 Morphology was characterized, and the results are as follows: Figure 3 As shown, by SEM and TEM Figure 5 , 6 It is evident that 3DOM-CuO-Tm has been revealed. 0.1 A similar three-dimensional ordered porous structure, with its pore diameter maintained at approximately 120 nanometers. Furthermore, Figure 7 Medium-energy dispersive X-ray spectroscopy (EDS) elemental imaging clearly revealed the composition and uniform distribution characteristics of C, Cu, Tm, and O elements.

[0044] Example 2: This example utilizes the 3DOM-CuO-Tm prepared in Example 1. x A linear voltammetric method was used to test the electrocatalytic coupling reduction of CO2 and KNO3 to synthesize urea. Figure 8The apparatus, procedures, and data analysis are as follows: Electrochemical tests in an H-type electrolytic cell were conducted using an IVIUM Vertex C.EIS electrochemical workstation within a conventional three-electrode H-type electrolytic cell. The cathode and anode chambers were separated by a Nafion 117 membrane. Before use, the Nafion 117 membrane was pretreated sequentially with 5% H₂O₂, ultrapure water, 5% H₂SO₄, and ultrapure water, with each step performed at 80°C for 1 h. The working electrode was prepared using a loading of 0.12 mg cm⁻¹. -2 3DOM-CuO-Tm x Modified carbon paper electrode (SGL29BC, 1×1cm) 2 The preparation method of the catalyst ink is as follows: 6 mg of 3DOM-CuO-Tm x The catalyst and 3 mg of PTFE nanoparticles with a particle size of 200 nm were dispersed in a mixed solvent consisting of 500 μL of deionized water, 500 μL of isopropanol, and 12 μL of 5 wt.% Nafion solution, and sonicated for 1 h to form a uniform dispersion. Subsequently, 20 μL of this ink was drop-coated onto the surface of carbon paper and allowed to air dry for later use.

[0045] A platinum sheet was used as the counter electrode, and a saturated Ag / AgCl electrode (3M KCl) was used as the reference electrode. The cathode and anode chambers of the electrolytic cell were separated by a Nafion 117 membrane. Before testing, the cathode electrolyte was pre-saturated with CO2 or Ar, depending on the experimental conditions.

[0046] Electrochemical polarization curves were obtained by linear sweep voltammetry (LSV) at a scan rate of 5 mV s. -1 The steady-state curves were recorded after multiple cycles to stabilize the system. The test electrolytes included: (i) a 0.3 M KHCO3 + 0.01 M KNO3 saturated CO2 system, (ii) a 0.3 M KHCO3 + 0.01 M KNO3 saturated Ar system, and (iii) a 0.3 M KHCO3 saturated Ar system.

[0047] All potentials are converted to reversible hydrogen electrode (RHE) according to the following formula: ERHE = E Ag / AgCl + 0.059 × pH + 0.197 V.

[0048] LSV results indicate that ( Figure 9 In a CO2-saturated electrolyte, 3DOM-CuO-Tm 0.1 The current density was significantly higher than that under Ar atmosphere conditions. This indicates that the introduction of CO2 caused the 3DOM-CuO-Tm 0.1The earlier reaction initiation potential on the surface indicates that a new electrochemical reaction pathway may have been introduced into the system. This phenomenon will be further verified by product analysis in Example 3.

[0049] Example 3: This example utilizes the 3DOM-CuO-Tm prepared in Example 1. x Perform performance testing:

[0050] (1) The performance of electrocatalytic coupling reduction of CO2 and KNO3 to synthesize urea was tested. The steps and data analysis are as follows:

[0051] The working electrode in the flow electrolyzer was prepared using the same method as that used in the H-type electrolyzer. Specifically, 20 μL of catalyst ink was dropped onto a 1×1 cm² plate using a micropipette. 2 Carbon paper electrodes were uniformly loaded onto the surface using a drop-coating method and dried for later use. In the flowing electrolytic cell, platinum foil was used as the counter electrode, and an Hg / HgO electrode as the reference electrode. The cathode and anode chambers were separated by a Nafion 117 proton exchange membrane. The cathode electrolyte volume was 25 mL, with an optimized composition of 0.3 M KHCO3 and 0.01 M KNO3, saturated with CO2. Before testing, the cathode electrolyte was pre-saturated with CO2. During electrolysis, the CO2 flow rate was controlled at 40 mL / min using a mass flow controller. -1 The electrolyte flow rate in the flow cell was controlled by a peristaltic pump (set to 50% of total power). Before electrochemical testing, the electrodes were activated using cyclic voltammetry. Activation conditions were: a mixed electrolyte solution of 0.3 M KHCO3 and 0.01 M KNO3, a potential range of -0.1 to -1.7 V (vsRHE), and a scan rate of 50 mV / s. -1 The process was repeated 50 times. After activation, the flowing electrolyzer was rinsed with ultrapure water to remove any residual urea and NH3 contaminants. Subsequently, in a mixed electrolyte of 0.3 M KHCO3 and 0.01 M KNO3, continuous CO2 bubbling (40 mL / min) was performed. -1 Under these conditions, a 30-minute pulse electrolysis test was performed, and the products were quantitatively analyzed.

[0052] A pulsed potential was applied to the working electrode using an electrochemical workstation (reaction 10s, pause 5s). During the reaction, high-purity CO2 (as a carbon source) was continuously introduced into the cathode chamber, with the CO2 flow rate controlled at 45 mL / min. -1 Meanwhile, the peristaltic pump flow rate was set to 50% of the total power. After reacting for 20 min, the electrolyte products were collected and subjected to quantitative analysis by ultraviolet spectroscopy.

[0053] (2) such as Figure 10As shown, the urea concentration was determined by the urease decomposition method. 20 mg of urease was dissolved in 30 mL of PBS (10X) buffer to prepare a solution with a concentration of 1 mg·L⁻¹. -1 A urease solution was prepared. Then, 1.8 mL of electrolyte solution was added to the above 0.2 mL solution. The resulting mixture was reacted in a water bath at 37 °C for 2 hours, and the ammonia produced by urea hydrolysis was determined by indophenol blue spectrophotometry. Simultaneously, the ammonia concentration in the same electrolyte sample without urease was analyzed using the same procedure. When urease is present, urea (CO(NH2)2) in the electrolyte decomposes into CO2 and two molecules of NH3. The total number of moles of ammonia in the solution (nurease) was determined spectrophotometrically and expressed as 2nurea + nammonia, where 2nurea corresponds to the ammonia produced by urea decomposition. Therefore, the number of moles of urea (nurea) is expressed by the formula (nurease - nammonia) / 2.

[0054] The ammonia content was determined quantitatively using the indophenol blue method. Two mL of electrolyte was taken from the electrochemical reactor and diluted with deionized water. Then, 2 mL of a 1 mol·L⁻¹ solution containing 5% (w / w) sodium citrate and 5% (w / w) salicylic acid was added to the diluted electrolyte. -1 Add sodium hydroxide solution, then add 1 mL of freshly prepared 0.05 mol / L sodium hypochlorite solution, and gently shake to mix. Finally, add 0.2 mL of 1% (w / v) sodium nitroferricyanide solution. Incubate the mixture at room temperature in the dark for 2 hours, then perform UV-Vis spectroscopy analysis at 655 nm. Plot a calibration curve using ammonium chloride standard solution, comparing concentration with absorbance. The fitted curve (y = 0.09043x + 0.06855, R² = 0.999) shows a strong linear correlation between absorbance and ammonium chloride concentration; this result is from three independent calibration experiments.

[0055] (3) Figure 11 and 12 3DOM-CuO-Tm was demonstrated 0.1 The Faradaic efficiency and yield of urea electrosynthesis were measured in the potential range of -0.5 to -1.7 V (vs. RHE), with the highest urea yield reaching 94.46 mmol h⁻¹. -1 g catal. -1 (-1.5 V vs. RHE), with a maximum FE of 31.66% (-0.7 V vs. RHE). Furthermore, to determine the optimal Tm doping level, we systematically evaluated DC-CuO-Tm doping ratios with different doping proportions. x Catalysts (including DC-CuO-Tm) 0.05 DC-CuO-Tm0.1 and DC-CuO-Tm 0.15 The electrocatalytic performance of (e.g.) Figure 13 As shown, 3DOM-CuO-Tm 0.1 The highest yield was observed in this series of samples, indicating that appropriate Tm incorporation plays a key role in enhancing urea synthesis performance.

[0056] To verify the advantages of DC-CuO-Tm in terms of stability, Figure 14 This demonstrates the excellent stability of the catalyst throughout a continuous potentiostatic electrolysis process lasting up to 110 h, maintaining a constant strength of approximately 35 mA cm⁻¹. -2 A stable current density was achieved, and the urea yield remained stable at 56 mmol / h. -1 g catal. -1 This fully demonstrates that 3DOM-CuO-Tm 0.1 Excellent long-term stability.

[0057] In summary, the method of this invention produces a three-dimensional ordered porous rare-earth-doped copper oxide catalyst, 3DOM-CuO-Tm. 0.1 Achieving highly selective and high Faradaic efficiency electrocatalytic reduction of CO2 and NO at room temperature and pressure. 3- Synthetic urea, as demonstrated in this invention, exhibits a high yield of up to 94.46 mmol h under optimal conditions. -1 g catal. -1 (-1.5V vs. RHE) yield, with the highest FE reaching 31.66% (-0.7V vs. RHE).

[0058] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A method for preparing a rare earth-doped copper oxide catalyst, characterized in that, The steps include: First, polystyrene microspheres were prepared using a soap-free emulsion polymerization method; then, a precursor solution was prepared. The prepared polystyrene microspheres were then added to the precursor solution, mixed, and dried. Finally, the obtained solid precursor was calcined to obtain a rare earth-doped copper-based catalyst with a three-dimensional ordered porous structure.

2. The method for preparing rare earth-doped copper oxide catalyst according to claim 1, characterized in that, The specific steps include: S1. Styrene solution and polyvinylpyrrolidone solution are mixed, heated and stirred, and then potassium persulfate solution is added to obtain monodisperse colloidal polystyrene microsphere emulsion; S2. After high-speed centrifugation, the supernatant of the monodisperse colloidal polystyrene microsphere emulsion is removed, and the white solid is dried to obtain polystyrene microspheres. S3. Tm(NO3)3·5H2O and Cu(NO3)2·3H2O are completely dissolved in a solution of ethanol and water under continuous stirring at a certain molar ratio to obtain a precursor solution. S4. Add polystyrene microspheres to the precursor solution, stir to obtain a suspension; dry the suspension to obtain a solid precursor; S5. The solid precursor is calcined and cooled to room temperature to obtain a three-dimensional ordered porous rare earth-doped copper oxide catalyst.

3. The method for preparing rare earth-doped copper oxide catalyst according to claim 2, characterized in that, In step S1, an aqueous solution containing 0.1-2 g of polyvinylpyrrolidone is introduced into 13 mL of styrene; nitrogen gas is then introduced into the mixture and heated and stirred in a water bath; then an aqueous solution containing 0.2 g of potassium persulfate is added to initiate the polymerization of styrene. The mixture was then stirred to obtain a monodisperse colloidal polystyrene microsphere emulsion.

4. The method for preparing the rare earth-doped copper oxide catalyst according to claim 1, characterized in that, The water bath heating and stirring temperature in S1 is 60–90 ℃, the stirring speed is 200–500 rpm, and the stirring time is 20–28 h.

5. The method for preparing rare earth-doped copper oxide catalyst according to claim 1, characterized in that, The monodisperse colloidal polystyrene microsphere emulsion in S2 was centrifuged at a speed of 8000–10000 rpm for 20 min. The milky white solid obtained by centrifugation was dried at a temperature of 50–80 ℃ for 12–18 h.

6. The method for preparing the rare earth-doped copper oxide catalyst according to claim 1, characterized in that, The molar ratio of Tm(NO3)3·5H2O and Cu(NO3)2·3H2O in S3 is 1:

10.

7. The method for preparing rare earth-doped copper oxide catalyst according to claim 1, characterized in that, The ratio of ethanol to water in S3 is 1:

1.

8. The method for preparing rare earth-doped copper oxide catalyst according to claim 1, characterized in that, In S4, the mass ratio of polystyrene microspheres to precursor is 2:

1. After mixing, the mixture is placed in a vacuum oven and immersed at room temperature for 9-16 hours.

9. The method for preparing the rare earth-doped copper oxide catalyst according to claim 1, characterized in that, The solid precursor in S5 was calcined in a muffle furnace as follows: First, the temperature was raised to 115℃ at a rate of 5℃ / min and held for 6 hours; then, the temperature was raised to 250℃ at a rate of 5℃ / min and held for 12 hours; next, the temperature was raised to 310℃ and held for 2 hours; thereafter, the temperature was gradually raised to 310℃, 330℃, 350℃, 370℃ and 400℃ at a rate of 0.5℃ / min, and held for 2.5 hours at each temperature point.

10. An application of a rare earth-doped copper oxide catalyst, characterized in that, The earth-doped copper oxide catalyst of claim 2 is used for NO3 - In the process of CO2 electrocatalytic synthesis of urea.

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