Preparation method and application of Cu / CeO2-FLPs electro-catalysis nano material of copper-doped hindered Lewis acid-base pair

Abstract

The invention discloses a copper-doped hindered Lewis acid-base pair (FLPs) electro-catalytic nano material, which is characterized in that a firewood-shaped Ce-MOFs precursor is synthesized by a solvothermal method, and is doped with trace copper after pyrolysis, and the expression of the precursor is Cu / CeO2-FLPS. The material shows high selectivity, stability and high conversion frequency to methane under large current. Accordingly, the inventor also establishes a corresponding preparation method, cerium nitrate and trimesic acid are taken as raw materials, a Ce-MOFs precursor is synthesized by adopting a solvent method, and CeO2-FLPs is obtained after high-temperature calcination; then, copper nitrate is used as a copper source, different copper contents are impregnated and loaded on CeO2-FLPs, and low-temperature calcination is carried out to synthesize the catalyst. According to the method, a simple doping strategy is provided to synthesize Cu / CeO2-FLPS materials with different FLPs concentrations, molecular FLPs chemistry and heterogeneous electro-catalysis are associated, application of a copper-based catalyst of FLPs in the field of electro-catalysis is initiated, and the problem that doped copper sites are unstable is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy nanomaterials, and particularly relates to a preparation method and application of a copper-doped frustrated Lewis pair electrocatalytic nanomaterial. Background Art

[0002] Driven by renewable energy, the electrocatalytic carbon dioxide reduction reaction with water as the reaction medium provides a highly promising solution for the production of high-value chemicals and fuels. Methane, as one of the products, has wide application value. Methane is not only the main component of natural gas and is widely used as a civil clean energy, but also the basic raw material for the synthesis of many chemical products, such as for the preparation of syngas, hydrogen, methanol, synthetic ammonia, etc. Interestingly, methane also has important significance in planetary science research. For example, the methane detected on Mars and Titan may be related to life activities, and liquid methane can be used as fuel to launch the SpaceX Starship for space exploration.

[0003] However, the formation of a methane molecule requires the participation of 8H + and 8e - . Due to the complexity of the reaction path in the water medium and the competition of the hydrogen evolution reaction, the high selectivity of the methane product is limited. The intermediate *COOH combines with H + to form *CO, which is considered to be a potential rate-determining step for the reduction of CO2 to methane. The source of protons is the reaction medium water, while the generation of protons is restricted in alkaline electrolytes. Combining water activation and the optimization of the adsorption strength of key intermediates is an important way to achieve efficient carbon dioxide to methane preparation. Copper is a commonly used catalyst for reducing CO2 to hydrocarbons. However, due to the high thermal stability of copper, it is not suitable for water activation, which is a major challenge. Therefore, synthesizing a new type of copper-based catalyst with high selectivity and high stability for electrocatalytic reduction of carbon dioxide is still a challenging and significant topic. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a preparation method and application of a Cu / CeO2-FLPs electrocatalytic nanomaterial doped with copper-doped frustrated Lewis pairs.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The copper-doped frustrated Lewis pair electrocatalytic nanomaterial is prepared by doping trace amounts of copper into the firewood-shaped Ce-MOFs precursor synthesized by the solvothermal method after high-temperature pyrolysis to obtain a broom-shaped nanomaterial, and its expression is Cu / CeO2-FLPs.

[0007] The length distribution of the nanomaterial is 4.63 ± 0.06 microns, and the width distribution is 1.95 ± 0.06 microns.

[0008] Preparation method of copper-doped frustrated Lewis pair electrocatalytic nanomaterials, comprising the following steps:

[0009] <1> Using cerium nitrate hexahydrate as the cerium source and cetyltrimethylammonium bromide as the surfactant, prepare solution A;

[0010] <2> Using trimesic acid as the organic ligand and triethylamine as the regulator, prepare an aqueous BTC solution, i.e., solution B;

[0011] <3> Mix and stir the solution A obtained in step <1> with the solution B obtained in step <2>, and obtain a Ce-MOFs precursor through centrifugal separation;

[0012] <4> Calcinate the Ce-MOFs precursor obtained in step <3> at high temperature to obtain CeO2-FLPs;

[0013] <5> Using copper nitrate as the copper source, impregnate different contents of copper and load it on the CeO2-FLPs obtained in <4>, and obtain Cu / CeO2-FLPs through low-temperature calcination.

[0014] Step (1) is carried out as follows: Mix the methanol solution of cerium nitrate hexahydrate, cetyltrimethylammonium bromide and deionized water and stir until completely dissolved to obtain.

[0015] In step (1): The stirring temperature is room temperature, the rotation speed is 400 RPM, and the stirring time is 20 min.

[0016] Step (2) is carried out as follows: Dissolve trimesic acid in deionized water, add triethylamine to adjust the pH to obtain.

[0017] In step (2): The stirring temperature is room temperature, the rotation speed is 400 RPM, and the stirring time is 20 min.

[0018] Step (3) is carried out as follows: Mix and stir the solution A obtained in step <1> with the solution B obtained in step <2>, carry out centrifugal separation, then wash and dry to obtain.

[0019] In step (3): The mixing and stirring temperature is room temperature, the rotation speed is 400 RPM, and the stirring time is 30 min. The centrifugation speed is 8000 RPM, and the centrifugation time is 5 min; The washing solvent is ethanol, and the washing times are 4 times; The drying conditions are 60 °C and 12 h.

[0020] Step (4) is carried out as follows: Grind the Ce-MOFs precursor obtained in step <3>, place it in a muffle furnace, raise the temperature to the target temperature at a set heating rate and keep it calcined at a constant temperature, and cool to obtain CeO2-FLPs.

[0021] In step (4): the heating rate is 5 °C / min, the calcination temperature is 800 °C, and the isothermal time is 1 h.

[0022] Step (5) is carried out as follows: the CeO2-FLPs obtained in step <4> are dispersed in deionized water, a copper nitrate trihydrate solution is added, after stirring and impregnating, centrifugal separation is carried out, and vacuum drying is carried out; the dried sample is placed in a tubular furnace and calcined at a low temperature under a reducing atmosphere to obtain Cu / CeO2-FLPs.

[0023] In step (5): the stirring temperature is room temperature, the rotation speed is 450 RPM, and the stirring time is 12 h; the centrifugal rotation speed is 8000 RPM, and the centrifugal time is 5 min; the vacuum drying conditions are 60 °C and 12 h; the calcination atmosphere is hydrogen, the calcination temperature is 350 °C, the heating rate is 5 °C / min, and the isothermal time is 1 h.

[0024] The above-mentioned Cu / CeO2-FLPs electrocatalytic nanomaterial with copper-doped frustrated Lewis pairs or the base electrocatalytic nanomaterial obtained by the preparation method is used as an electrocatalyst for the electrocatalytic reduction of carbon dioxide.

[0025] Aiming at the problem that most current carbon dioxide reduction catalysts exhibit low selectivity and turnover frequency, the inventor developed a Cu / CeO2-FLPs electrocatalytic nanomaterial with copper-doped frustrated Lewis pairs. A firewood-shaped Ce-MOFs precursor was synthesized by a solvothermal method, and after high-temperature pyrolysis, a trace amount of copper was doped, and its expression is Cu / CeO2-FLPs. Research shows that this nanomaterial has a broom-shaped structure and exhibits high selectivity and high turnover frequency for methane products at high current densities. Therefore, the Cu / CeO2-FLPs electrocatalytic nanomaterial with copper-doped frustrated Lewis pairs of the present invention can be used as an electrocatalyst for electrocatalytic reduction of carbon dioxide to prepare methane. This material meets the requirements of green energy development and has important application potential in the field of low-carbon environmental protection, and has significant research significance for achieving sustainable development goals.

[0026] Accordingly, the inventor also established a corresponding preparation method for this electrocatalytic nanomaterial. This method uses cerium nitrate hexahydrate as the cerium source, cetyltrimethylammonium bromide as the surfactant, trimesic acid as the organic ligand, and triethylamine as the regulator, and synthesizes the Ce-MOFs precursor by the solvothermal method; the Ce-MOFs precursor is calcined at high temperature, copper ions are impregnated using copper nitrate as the copper source, and the Cu / CeO2-FLPs material with different FLPs concentrations is obtained through low-temperature calcination. This method proposes a simple doping strategy to synthesize Cu / CeO2-FLPs materials with different FLPs concentrations, connects molecular FLPs chemistry with heterogeneous electrocatalysis, and demonstrates high selectivity and high turnover frequency for carbon dioxide reduction to methane in a flow cell test. In summary, the present invention pioneers the application of FLPs copper-based catalysts in the field of electrocatalysis, overcomes the problem of unstable doped copper sites, and reveals the structure-activity relationship of FLPs copper-based catalysts for preparing methane. Description of the Drawings

[0027] Figure 1 It is the X-ray powder diffraction pattern of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial in Example 1.

[0028] Figure 2 It is the scanning electron microscope image of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial in Example 1.

[0029] Figure 3 It is the transmission electron microscope image of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial in Example 1.

[0030] Figure 4 It is the particle size distribution diagram of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial in Example 1.

[0031] Figure 5 It is the element distribution diagram of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial in Example 1.

[0032] Figure 6 It is the CO2-BET adsorption diagram of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial in Example 1.

[0033] Figure 7 It is the linear sweep voltammogram of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial in Example 1.

[0034] Figure 8 It is the Faraday efficiency diagram of methane and hydrogen products of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial in Example 1.

[0035] Figure 9 It is the partial current density diagram of methane and hydrogen products at each potential of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial in Example 1.

[0036] Figure 10 It is the turnover frequency diagram of methane products at each potential of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial in Example 1.

[0037] Figure 11 It is the stability test diagram of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial at the optimal Faraday efficiency potential in Example 1. Detailed implementation manners

[0038] Example 1 Preparation of a copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial

[0039] (1) Mix 30 mL of a 0.1 M methanol solution of cerium nitrate hexahydrate, 48 mL of a 0.1 M cetyltrimethylammonium bromide solution, and 30 mL of deionized water and stir to obtain Solution A.

[0040] (2) Dissolve 0.921 g of trimesic acid in 40 mL of deionized water, add 1.66 mL of triethylamine, take out 24 mL of the mixed solution, mix it with 72 mL of deionized water and stir evenly to obtain Solution B.

[0041] (3) After mixing Solution A and Solution B, continue to stir for 30 minutes. Collect the mixture by centrifugation, wash it four times with ethanol, and dry it at 60 °C for 12 h to obtain a white Ce-MOFs precursor.

[0042] (4) Grind the above Ce-MOFs precursor and place it in a muffle furnace. Heat it to 800 °C at a heating rate of 5 °C / min, and calcine it at a constant temperature for 1 h, then cool it to room temperature to obtain CeO2-FLPs.

[0043] (5) Disperse 100 mg of cerium oxide and 15.2 mg of copper nitrate trihydrate (the molar ratio of copper ions to cerium oxide is 10%) in 20 mL of deionized water, stir for 12 hours, collect the yellow solid product by centrifugation, vacuum dry it at 60 °C for 12 h, place it in a hydrogen atmosphere tube furnace, heat it to 350 °C at 5 °C / min and then calcine it for 1 h to obtain the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial.

[0044] Example 2 Preparation of a copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial

[0045] (1) Mix 30 mL of a 0.1 M methanol solution of cerium nitrate hexahydrate, 48 mL of a 0.1 M cetyltrimethylammonium bromide solution, and 30 mL of deionized water and stir to obtain Solution A.

[0046] (2) Dissolve 0.921 g of trimesic acid in 40 mL of deionized water, add 1.66 mL of triethylamine, take out 24 mL of the mixed solution, mix it with 72 mL of deionized water and stir evenly to obtain Solution B.

[0047] (3) After mixing Solution A and Solution B, continue stirring for 30 minutes. Collect the mixture by centrifugation, wash it four times with ethanol, and dry it at 60 °C for 12 h to obtain a white Ce-MOFs precursor.

[0048] (4) Grind the above Ce-MOFs precursor and place it in a muffle furnace. Heat it to 800 °C at a heating rate of 5 °C / min, and calcine it at a constant temperature for 1 h, then cool it to room temperature to obtain CeO2-FLPs.

[0049] (5) Disperse 100 mg of cerium oxide and 7.6 mg of copper nitrate trihydrate in 20 mL of deionized water, stir for 12 hours, collect the yellow solid product by centrifugation, dry it in vacuo at 60 °C for 12 h, place it in a tubular furnace under a hydrogen atmosphere, heat it to 350 °C at a rate of 5 °C / min and then calcine it for 1 h to obtain the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial.

[0050] Example 3 Preparation of a copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial

[0051] (1) Mix 30 mL of a 0.1 M methanol solution of cerium nitrate hexahydrate, 48 mL of a 0.1 M cetyltrimethylammonium bromide solution, and 30 mL of deionized water and stir to obtain Solution A.

[0052] (2) Dissolve 0.921 g of trimesic acid in 40 mL of deionized water, add 1.66 mL of triethylamine, take out 24 mL of the mixed solution, mix it with 72 mL of deionized water and stir evenly to obtain Solution B.

[0053] (3) After mixing Solution A and Solution B, continue stirring for 30 minutes. Collect the mixture by centrifugation, wash it four times with ethanol, and dry it at 60 °C for 12 h to obtain a white Ce-MOFs precursor.

[0054] (4) Grind the above Ce-MOFs precursor and place it in a muffle furnace. Heat it to 800 °C at a heating rate of 5 °C / min, and calcine it at a constant temperature for 1 h, then cool it to room temperature to obtain CeO2-FLPs.

[0055] (5) Disperse 100 mg of cerium oxide and 22.8 mg of copper nitrate trihydrate in 20 mL of deionized water, stir for 12 hours, collect the yellow solid product by centrifugation, dry it in vacuo at 60 °C for 12 h, place it in a tubular furnace under a hydrogen atmosphere, heat it to 350 °C at a rate of 5 °C / min and then calcine for 1 h to obtain the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial.

[0056] Example 4 Preparation of a copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial

[0057] (1) Mix 30 mL of a 0.1 M methanol solution of cerium nitrate hexahydrate, 48 mL of a 0.1 M cetyltrimethylammonium bromide solution and 30 mL of deionized water and stir to obtain Solution A.

[0058] (2) Dissolve 0.921 g of trimesic acid in 40 mL of deionized water, add 1.66 mL of triethylamine, take out 24 mL of the mixed solution, mix it with 72 mL of deionized water and stir evenly to obtain Solution B.

[0059] (3) After mixing Solution A and Solution B, continue stirring for 30 minutes. Collect the mixture by centrifugation, wash it four times with ethanol, and dry it at 60 °C for 12 h to obtain the white Ce-MOFs precursor.

[0060] (4) Grind the above Ce-MOFs precursor and place it in a muffle furnace, heat it to 800 °C at a heating rate of 5 °C / min, keep it at a constant temperature and calcine for 1 h, and cool it to room temperature to obtain CeO2-FLPs.

[0061] (5) Disperse 100 mg of cerium oxide and 30.4 mg of copper nitrate trihydrate in 20 mL of deionized water, stir for 12 hours, collect the yellow solid product by centrifugation, dry it in vacuo at 60 °C for 12 h, place it in a tubular furnace under a hydrogen atmosphere, heat it to 350 °C at a rate of 5 °C / min and then calcine for 1 h to obtain the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial.

[0062] Example 5 Preparation of a copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial

[0063] (1) Mix 30 mL of a 0.1 M methanol solution of cerium nitrate hexahydrate, 48 mL of a 0.1 M cetyltrimethylammonium bromide solution and 30 mL of deionized water and stir to obtain Solution A.

[0064] (2) Dissolve 0.921 g of trimesic acid in 40 mL of deionized water, add 1.66 mL of triethylamine, take out 24 mL of the mixed solution, mix it with 72 mL of deionized water and stir evenly to obtain Solution B.

[0065] (3) Mix solution A and solution B and continuously stir for 30 minutes. Collect the mixture by centrifugation, wash it four times with ethanol, and dry it at 60 °C for 12 h to obtain a white Ce-MOFs precursor.

[0066] (4) Grind the above Ce-MOFs precursor and place it in a muffle furnace. Heat it to 800 °C at a heating rate of 5 °C / min, and calcine it at a constant temperature for 1 h. Cool it to room temperature to obtain CeO2-FLPs.

[0067] (5) Disperse 100 mg of cerium oxide and 38 mg of copper nitrate trihydrate in 20 mL of deionized water, stir for 12 hours, collect the yellow solid product by centrifugation, vacuum dry it at 60 °C for 12 h, place it in a tubular furnace under a hydrogen atmosphere, heat it to 350 °C at 5 °C / min and then calcine it for 1 h to obtain the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial.

[0068] Weigh 10 mg each of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterials obtained from the above Examples 1 to 5, mix them with 950 μL of absolute ethanol and 50 μL of Nafion solution (5 wt%), and ultrasonically treat for 1 h to obtain a uniformly dispersed catalyst ink. Use a pipette to take 225 μL of the catalyst ink in small amounts and apply it evenly on a 1.5×1.5 cm 2 carbon paper (gas diffusion layer). Keep irradiating with an infrared lamp during the coating process, and perform the next coating after the previous coating is nearly dry. Finally, a gas diffusion electrode with a catalyst loading of 1 mg / cm 2 is prepared. A three-electrode system is used for testing: use the prepared gas diffusion electrode as the working electrode, a 3.5 mol / L saturated silver / silver chloride electrode in potassium chloride as the reference electrode, and a platinum sheet as the counter electrode. The cathode and anode are separated by an anion exchange membrane, and 1 mol / L potassium hydroxide electrolyte is injected into each respectively. The electrolyte is circulated by a peristaltic pump (cathode flow rate 5 mL / min, anode flow rate 3 mL / min). High-purity carbon dioxide (99.999%) is delivered to the cathode chamber at a flow rate of 20 sccm through a mass flow controller.

[0069] Accordingly, the obtained materials are detected and investigated. The results of Example 1 are as Figures 1 to 11 shown, specifically:

[0070] Figure 1 is the X-ray powder diffraction pattern of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial of Example 1. The (111), (220), (200), and (311) characteristic peaks of CeO2 in the Cu / CeO2-FLPs electrocatalytic nanomaterial are observed.

[0071] Figure 2 It is the scanning electron microscope image of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial in Example 1. It is observed that the Cu / CeO2-FLPs electrocatalytic nanomaterial has a broom-like structure.

[0072] Figure 3 It is the transmission electron microscope image of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial in Example 1. It further confirms the broom-like structure of the Cu / CeO2-FLPs electrocatalytic nanomaterial.

[0073] Figure 4 It is the particle size distribution diagram of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial in Example 1. It is confirmed that the length distribution of the broom-like Cu / CeO2-FLPs nanomaterial is 4.63 ± 0.06 microns, and the width distribution is 1.95 ± 0.06 microns.

[0074] Figure 5 It is the element distribution diagram of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial in Example 1. It is confirmed that the elements of Cu, Ce, and O are evenly distributed in the Cu / CeO2-FLPs electrocatalytic nanomaterial.

[0075] Figure 6 It is the CO2-BET adsorption diagram of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial in Example 1. It is confirmed that the Cu / CeO2-FLPs electrocatalytic nanomaterial has good CO2 adsorption capacity.

[0076] Figure 7 It is the linear sweep voltammogram of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial in Example 1. It can be seen that compared with the Ar atmosphere, the Cu / CeO2-FLPs electrocatalytic nanomaterial is in the CO2 atmosphere

[0077] Figure 8 It is the Faraday efficiency diagram of the methane and hydrogen products of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial in Example 1. This electrocatalytic nanomaterial has a high selectivity for methane at each potential, and the Faraday efficiency of methane is as high as 78.04% at -1.8 V vs. RHE, showing excellent methane selectivity.

[0078] Figure 9 It is the partial current density diagram of the methane and hydrogen products of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial at each potential. The partial current density of methane of the Cu / CeO2-FLPs electrocatalytic nanomaterial is greater than that of hydrogen.

[0079] Figure 10 It is the conversion frequency diagram of methane products at each potential of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial in Example 1. The Cu / CeO2-FLPs electrocatalytic nanomaterial has a relatively high conversion frequency and a relatively high density of catalytic active sites.

[0080] Figure 11 It is the stability test diagram of the copper-doped frustrated Lewis pair Cu / CeO2-FLPs electrocatalytic nanomaterial at the optimal Faraday efficiency potential in Example 1. During the stability test of nearly 12 h, the Faraday efficiency of methane products of the Cu / CeO2-FLPs electrocatalytic nanomaterial basically remained unchanged and was stable above 65%.

[0081] The results of other examples are similar to those of Example 1, and no further figures and descriptions are given.

[0082] It should be noted that

[0083] The difference between Example 1 and Examples 2-5 lies in the different copper loadings. The molar ratios of copper ions to cerium oxide are 10%, 5%, 15%, 20%, and 25% respectively. The selectivity differences of copper doping amounts for the reduction of carbon dioxide to produce methane are mainly explored. The order of methane Faraday efficiency of them is: 10% > 15% > 5% > 20% > 25%. The copper doping amount has a regulating effect on the FLPs concentration on CeO2. When the doping content is 10%, it has the best FLPs concentration and moderate particle size distribution, which is conducive to the adsorption of CO2 and the dissociation of water, provides sufficient proton sources for the methane generation path, and promotes the generation of methane. Therefore, it shows the optimal selectivity and conversion frequency in the reduction of CO2 to produce methane.

Claims

1. A copper-doped hindered Lewis acid-base pair (FLPs) electrocatalytic nanomaterial, characterized in that: The wood-like Ce-MOFs precursor was synthesized by a solvothermal method and then doped with trace amounts of copper after high-temperature pyrolysis to obtain a broom-like nanomaterial, which was expressed as Cu / CeO2-FLPS.

2. The copper-based electrocatalytic nanomaterial according to claim 1, characterized in that: The broom-shaped nanomaterial has a length distribution of 4.63±0.06 microns and a width distribution of 1.95±0.06 microns.

3. The method for preparing the copper-doped FLPs electrocatalytic nanomaterial according to claim 1, characterized in that The following steps are involved: <1> Solution A was prepared using cerium nitrate hexahydrate as a cerium source and hexadecyltrimethylammonium bromide as a surfactant; <2> Using trimesic acid as an organic ligand and triethylamine as a regulator, a BTC aqueous solution, i.e., solution B, was prepared; <3> Step <1> The obtained solution A and step <2> The obtained solution B is mixed and stirred, and the Ce-MOFs precursor is obtained by centrifugal separation; <4> Step <3> The obtained Ce-MOFs precursor is calcined at high temperature to obtain CeO2-FLPs; <5> Using copper nitrate as the copper source, different contents of copper were loaded on <4> The obtained CeO2-FLPs were calcined at low temperature to obtain Cu / CeO2-FLPS.

4. The preparation method according to claim 3, characterized in that Step (1) is performed as follows: a methanol solution of cerium nitrate hexahydrate, hexadecyltrimethylammonium bromide and deionized water are mixed and stirred until they are completely dissolved to obtain a solution A.

5. The preparation method according to claim 3, characterized in that Step (2) is performed as follows: dissolve trimesic acid in deionized water, add triethylamine to adjust the pH, and obtain solution B.

6. The preparation method according to claim 3, characterized in that Step (3) is performed as follows: solution A and solution B are mixed and stirred to react, and then centrifuged, washed and dried to obtain a Ce-MOFs precursor.

7. The preparation method according to claim 4, characterized in that In step (1): the stirring temperature is room temperature, the rotation speed is 400 RPM, and the stirring time is 20 min.

8. The preparation method according to claim 5, characterized in that In step (2): the stirring temperature is room temperature, the rotation speed is 400 RPM, and the stirring time is 20 min.

9. The preparation method according to claim 6, characterized in that In step (3), the mixing and stirring temperature is room temperature, the speed is 400 RPM, and the stirring time is 30 min. The centrifugal speed is 8000 RPM, and the centrifugal time is 5 min. The washing solvent is ethanol, and the washing times are 4 times. The drying conditions are 60°C and 12 h.

10. The preparation method according to claim 3, characterized in that Step (4) is as follows: <3> The obtained Ce-MOFs precursor is ground and placed in a muffle furnace, heated to the target temperature at a set heating rate and calcined at a constant temperature, and then cooled to obtain CeO2-FLPs.

11. The preparation method according to claim 10, characterized in that In step (4): the heating rate is 5°C / min, the calcination temperature is 800°C, and the constant temperature time is 1h.

12. The preparation method according to claim 3, characterized in that Step (5) is performed as follows: <4> The obtained CeO2-FLPs are dispersed in deionized water, and copper nitrate trihydrate solution is added. After stirring and impregnation, the mixture is centrifuged and vacuum dried. The dried sample is placed in a tube furnace and calcined at low temperature under a reducing atmosphere to obtain Cu / CeO2-FLPs.

13. The preparation method according to claim 12, characterized in that In step (5), the stirring temperature is room temperature, the rotation speed is 450 RPM, and the stirring time is 12 h; the centrifugal speed is 8000 RPM, and the centrifugal time is 5 min; the vacuum drying conditions are 60°C and 12 h; the calcination atmosphere is hydrogen, the calcination conditions are 350°C, the heating rate is 5°C / min, and the constant temperature time is 1 h.

14. The copper-doped FLPs electrocatalytic nanomaterial according to claim 1 or the copper-doped FLPs electrocatalytic nanomaterial obtained by any one of the preparation methods of claims 2 to 13 is used as an electrocatalyst for electrocatalytic reduction of carbon dioxide, characterized in that: The material has high selectivity, high stability and high conversion frequency for methane under high current.

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