Supported ag / lanthanide oxide nanocomposite and application thereof

Abstract

The application discloses a supported Ag / lanthanide oxide nanocomposite and application thereof. The application first obtains a composite phase precursor through a sol-gel reaction, and then obtains the product through high-temperature calcination. The product is mixed with conductive carbon black and the like to prepare an ink slurry, the ink slurry is drop-coated on a carrier to prepare an electrode, and the electrode is further used in an electrochemical carbon dioxide reduction reaction. In the initial stage of the reduction reaction, part of the doped silver is rapidly precipitated in situ on the surface of the carrier oxide, which indicates that the silver is connected to each other to form abundant interfaces and oxygen defects. The structure promotes the formation of a large number of active sites, and is beneficial to the conversion of carbon dioxide into carbon monoxide. The material prepared by the application has a carbon monoxide preparation faradaic efficiency close to 98%, greatly reduces the consumption of noble metal silver, has a simple synthesis method and wide applicability and expandability, has certain industrial value, and can be expected to alleviate current climate and environmental problems.

Description

Technical Field

[0001] This invention relates to the field of electrochemical carbon dioxide reduction catalyst technology, specifically to a supported Ag / lanthanide oxide composite electrocatalyst, its preparation method, and its application in electrocatalytic carbon dioxide reduction. Background Technology

[0002] In recent decades, the massive consumption of non-renewable fossil fuels (such as coal and oil) has triggered a series of serious problems, including energy crises and environmental pollution, making global warming a focus of widespread international concern. [1] To effectively address this challenge, scientists from various countries have actively conducted research and proposed a variety of innovative technologies to capture, store, and convert carbon dioxide in the atmosphere. [2] Among these technologies, utilizing electricity generated from renewable and clean energy sources (including solar, wind, and tidal power) to reduce carbon dioxide molecules into fossil fuels such as carbon monoxide, methane, ethylene, or ethanol, as well as high-value-added chemicals, has become one of the most promising technological pathways. [3] This technological solution not only helps reduce the concentration of carbon dioxide in the atmosphere, thereby alleviating the environmental crisis, but also converts intermittent and geographically limited clean energy into storable chemical energy, which can then be used to produce high-value-added products, achieving a dual benefit of environmental protection and economic gains. However, due to the chemical inertness of carbon dioxide molecules and the presence of side reactions such as hydrogen evolution at the cathode, the conversion efficiency of the electrochemical process is somewhat limited. [4] Therefore, exploring and developing electrocatalysts that are easy to prepare, have a wide range of applications, and exhibit superior performance has become an essential approach to achieving large-scale commercial applications in the future.

[0003] Among the many reported catalyst types, silver-based metal materials have attracted widespread attention from researchers due to their high selectivity in the electrochemical reduction of carbon dioxide to carbon monoxide. For example, Salehi-khojin's team was the first to experimentally study the effect of silver nanoparticle size variation on its electrocatalytic reduction performance, and successfully prepared silver nanoparticles with diameters ranging from 1 to 200 nm. [5] The results showed that the catalytic activity of these particles for carbon dioxide reduction exhibited a volcano-like variation with decreasing particle diameter. Liu et al. prepared triangular-shaped silver nanoparticles (Tri-Ag-NPs) using a direct chemical reduction method and compared them with bulk silver nanoparticles of the same size (SS-Ag-NPs). They found that Tri-Ag-NPs showed significantly improved Faraday efficiency and energy conversion performance, explaining the close correlation between catalyst performance and material microstructure. [6]In addition to studying the size and morphology of catalysts, researchers have also focused on the influence of catalyst supports and interfaces on catalytic performance. For example, Bao's research group conducted a preliminary study on the application of the gold / silver-cerium dioxide interface in the electrochemical carbon dioxide reduction process. Density functional theory calculations showed that interfacial catalysis is the main active site in the carbon dioxide catalytic reaction. [7] Therefore, how to obtain low-load, high-activity catalytic materials through simpler preparation processes, further elucidate the reasons for their performance changes in electrochemical carbon dioxide reduction reactions, and expand their application scope still require in-depth exploration and discovery.

[0004] References

[0005] [1] Fei L, Sun H, Xu

[0006] [2]Tan KB,Xu K,Cai D,et al.Rational design of bifunctional catalystswith properintegration manners for CO and CO2 hydrogenation into value-addedproducts:Areview[J].Chemical Engineering Journal,2023,463:142262.

[0007] [3]Seh ZW,Kibsgaard J,Dickens CF,et al.Combining theory and experiment inelectrocatalysis:Insights into materials design[J].Science,2017,355(6321):eaad4998.

[0008] [4]Qin Y, Zhan G, Tang C, et al. Homogeneous vacancies-enhanced orbitalhybridization for selective and efficient CO2-to-CO electrocatalysis[J]. NanoLetters, 2023, 23(20):9227-9234.

[0009] [5]Salehi-Khojin A, Jhong HR M, Rosen BA, et al. Nanoparticle silvercatalysts thatshow enhanced activity for carbon dioxide electrolysis[J]. The Journal of PhysicalChemistry C, 2013, 117(4):1627-1632.

[0010] [6]Liu S, Tao H, Zeng L, et al. Shape-dependent electrocatalyticreduction of CO2 to COon triangular silver nanoplates[J]. Journal of the American chemical society, 2017, 139(6): 2160-2163.

[0011] [7]Gao D, Zhang Y, Zhou Z, et al. Enhancing CO2 electroreduction with themetal–oxide interface [J]. Journal of the American Chemical Society, 2017, 139(16): 5652-5655. Summary of the Invention

[0012] Purpose of the invention: The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a supported Ag / lanthanide oxide composite electrocatalyst, its preparation method, and its application in electrocatalytic carbon dioxide reduction.

[0013] Inventive Concept: This invention proposes an in-situ reconstructed silver / lanthanide oxide nanocatalyst with abundant interfacial properties and oxygen vacancies. The preparation method of this catalyst is simple and easy, and it enables efficient synthesis of carbon monoxide in applications involving the electroreduction of carbon dioxide.

[0014] To solve the above-mentioned technical problems, the present invention discloses the following technical solution:

[0015] The first aspect of the present invention provides:

[0016] A silver / lanthanide oxide nanocomposite material with a small amount of silver loading, wherein the Ag loading in the composite material is preferably in the range of 20-25 wt%, and the loading can be precisely controlled in the synthesis steps.

[0017] In some embodiments, the composite phase catalyst is supported by a lanthanide oxide, specifically Pr6O. 11 The catalyst comprises any one or a combination of several of La₂O₃, CeO₂, and Nd₂O₃; the active metal is silver. In some embodiments, the molecular formula of the composite phase catalyst is Ag / Pr₆O₃. 11 .

[0018] In some embodiments, the composite phase catalyst is nanospheres with a diameter ranging from 50 to 200 nm, such as 80, 100, 120, 150, and 180 nm. The diameter of the preferred catalyst nanospheres after in-situ reconstruction is further optimized to 40-100 nm.

[0019] In some embodiments, the composite material is tested by XPS and has an oxygen defect concentration of 17.87%-19.87%, and after testing for carbon dioxide electroreduction performance, its oxygen defect concentration is further increased to 21.88%-23.88%.

[0020] A second aspect of the invention provides:

[0021] The preparation method of the silver / lanthanide oxide nanocomposite catalyst described in the first aspect above includes the following steps:

[0022] (1) Dissolve lanthanide nitrate and silver nitrate in deionized water according to the stoichiometric ratio and stir until homogeneous to obtain a clear and transparent solution;

[0023] (2) Add ethylenediaminetetraacetic acid (EDTA) and citric acid monohydrate (CA) to the obtained solution as metal ion complexing agents, add ammonia water to adjust the pH to 6.5-7.5, and heat and stir the solution until it becomes gel-like;

[0024] (3) The obtained gel was dried in an oven to obtain a precursor sample, and then calcined in an air atmosphere and ground to obtain a final powder sample.

[0025] In step (1), the lanthanide nitrate is any one or a combination of several of praseodymium nitrate, lanthanum nitrate, cerium nitrate and neodymium nitrate; the molar ratio of the lanthanide nitrate to silver nitrate is 1:1-4, such as 1:2 or 1:3.

[0026] In step (2), the mass ratio of silver nitrate, ethylenediaminetetraacetic acid and citric acid monohydrate is 1:5.8-7.8:8.9-10.9, such as 1:6.8:9.9.

[0027] In step (2), ammonia is added to adjust the pH to 6.5-7.5, such as 7.0.

[0028] In step (3), the drying temperature is 170-190℃, such as 180℃; the drying time is 7-10h, such as 8-9h.

[0029] In step (3), the temperature of heating and stirring the gel-like mixture is 90-110℃, such as 100℃; the heating and drying time is 7-10h.

[0030] In step (3), the calcination temperature is 500-900℃, such as 700℃; the calcination time is 1-3h, such as 2h.

[0031] A third aspect of the invention provides:

[0032] An electrode made from the silver / lanthanide oxide nanocomposite catalyst described in the first aspect above.

[0033] In some embodiments, the electrode is prepared by thoroughly mixing the silver / lanthanide oxide nanocomposite catalyst with a conductive agent, a dispersant, and a binder to obtain a slurry; the resulting slurry is then drop-coated onto the surface of a carrier and allowed to air dry.

[0034] In some implementations, commercial glassy carbon electrodes or commercial carbon fiber paper are used as carriers.

[0035] In some embodiments, the binder for the electrode is a Nafion solution or a PTFE binder.

[0036] In some embodiments, the conductive agent of the electrode is conductive carbon black.

[0037] In some embodiments, the dispersant for the cathode is an organic solvent, such as ethanol or isopropanol.

[0038] In some embodiments, the mass ratio of the composite material to the conductive agent is 1:0.5-2, such as 1:0.7-1.2.

[0039] In some embodiments, the ratio of the composite material, dispersant, and binder is 10 mg: 0.7-1.2 mL: 90-120 μL.

[0040] A fourth aspect of the present invention provides:

[0041] The application of the electrode described in the third aspect above as a cathode working electrode in the electrochemical carbon dioxide reduction reaction.

[0042] In one implementation, the application includes the following steps:

[0043] S1: Using the above-mentioned nanocomposite catalyst as the working electrode, a three-electrode system is constructed and assembled into an electrochemical cell;

[0044] S2: When CO2 is saturated by ventilation, a negative voltage is applied to carry out an electrochemical carbon dioxide reduction reaction.

[0045] In step S1,

[0046] In some embodiments, in the three-electrode system, silver-silver chloride is used as the reference electrode, and a platinum sheet or graphite rod is used as the counter electrode.

[0047] In step S2, the electrochemical reaction takes place in an H-type electrolytic cell.

[0048] In step S2, the electrochemical reaction uses a 0.01-0.2M KHCO3 solution as the electrolyte in the electrochemical cell, such as a 0.1M potassium bicarbonate solution.

[0049] In the initial stage of the reduction reaction, partially doped silver rapidly precipitates in situ onto the surface of the support oxide, indicating the formation of abundant interfaces and oxygen vacancies through interconnection. These structures promote the formation of numerous active sites, facilitating the conversion of carbon dioxide into carbon monoxide. The material prepared by this invention exhibits a carbon monoxide production Faraday efficiency approaching 98%, significantly reducing the consumption of the precious metal silver. The synthesis method is simple, widely applicable, and scalable, possessing considerable industrial value and the potential to alleviate current climate and environmental problems.

[0050] Beneficial effects:

[0051] The Ag-supported oxide composite catalyst prepared in this invention exhibits excellent crystallinity, presenting as a dark brown powder. By introducing silver doping, highly efficient active sites are formed between the metal and the support, thereby significantly improving the catalyst's conversion capacity for carbon dioxide molecules. Compared with traditional pure silver powder catalysts, the use of a small amount of silver not only optimizes catalytic performance but also significantly reduces the catalyst's preparation cost.

[0052] The nanocomposite electrocatalyst provided by this invention exhibits superior performance in catalyzing the conversion of carbon dioxide to carbon monoxide, significantly outperforming traditional silver powder catalysts. The findings regarding interfaces and oxygen defects in these studies provide important theoretical support for understanding the reaction mechanism of carbon dioxide electrocatalytic reduction, and also open new avenues for its application in reducing atmospheric carbon dioxide concentrations.

[0053] The silver / lanthanide oxide composite material with low silver loading of this invention can be produced by traditional sol-gel method, sodium borohydride reduction method, and other processes. The preparation process is simple and easy, and the mass proportion of silver in the material is relatively low, which greatly reduces the cost. The catalyst support is not only suitable for praseodymium oxide, but can also be extended to other lanthanide oxides and transition metal oxides, showing good potential for large-scale production and batch replacement manufacturing. Attached Figure Description

[0054] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0055] Figure 1 This is a flowchart illustrating the preparation process of the technical solution in this invention.

[0056] Figure 2 This is a schematic diagram of the two-phase structure of the composite catalyst prepared in Example 1 and Comparative Example 3 of this invention.

[0057] Figure 3 This refers to Ag / Pr6O involved in this invention. 11 Pr6O 11 Ag powder and Ag+Pr6O 11 The X-ray diffraction pattern.

[0058] Figure 4 These are the X-ray diffraction patterns of Ag / La2O3, Ag / CeO2, and Ag / Nd2O3 involved in this invention.

[0059] Figure 5 This refers to the Ag 3d orbital X-ray photoelectron spectra of Example 1 and its post-reaction sample as described in this invention.

[0060] Figure 6 The O1s orbital X-ray photoelectron spectra of Example 1 and its post-reaction sample, and Comparative Examples 1 and 3, as described in this invention.

[0061] Figure 7 The electron paramagnetic resonance spectra are those of Example 1 and its post-reaction sample, and Comparative Examples 1 and 3, as described in this invention.

[0062] Figure 8This is a scanning electron microscope image and particle size distribution of Example 1 and its post-reaction sample as described in this invention.

[0063] Figure 9 These are transmission electron microscope images of Embodiment 1 included in this invention at different magnifications.

[0064] Figure 10 The graphs show the normalized polarization curves of the catalysts in Example 1 and Comparative Examples 1, 2, and 3 of this invention in 0.1 M KHCO3 solution, and the relationship between the CO Faradaic efficiency of the catalysts and voltage.

[0065] Figure 11 This is a graph showing the stability test results of the catalyst in 0.1M KHCO3 solution of Example 1 included in this invention.

[0066] Figure 12 This is an electrochemical active area diagram of the catalysts in Example 1 and Comparative Examples 2 and 3 described in this invention.

[0067] Figure 13 These are the electrochemical impedance spectroscopy diagrams of the catalysts in Example 1 and Comparative Examples 2 and 3 of this invention.

[0068] Figure 14 This is a graph showing the relationship between CO Faraday efficiency and voltage in embodiments 2, 3, and 4 of this invention. Detailed Implementation

[0069] The present invention can be better understood from the following embodiments. However, those skilled in the art will readily understand that the descriptions in the embodiments are for illustrative purposes only and should not, and will not, limit the invention as detailed in the claims.

[0070] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0071] Currently, the large-scale application of electrocatalytic carbon dioxide reduction technology faces challenges mainly due to variations in product selectivity and high product separation costs. Among the many reduction products, carbon monoxide is considered one of the most promising for industrialization due to its excellent selectivity and relatively easy separation process. However, existing silver-based catalysts still require performance improvement and are relatively expensive. To address these issues, this invention proposes modifying silver-based catalyst materials to enhance their catalytic efficiency in carbon dioxide electroreduction and reduce the amount of silver required. Specifically, this invention selects lanthanide oxides, which lack carbon dioxide reduction catalytic activity, as the support for silver. A strong interaction between metallic silver and the support is achieved through chemical synthesis, thereby helping to enhance the active sites of the electrocatalytic reaction. Furthermore, the synthesis temperature of silver / lanthanide oxides is relatively low, ranging from 500-900℃, where metallic silver can form at lower temperatures, while oxide formation requires temperatures above 500℃. Simultaneously, the degree of interaction between the metal and the oxide can be controlled by adjusting the calcination temperature. While high temperatures (above 900℃) lead to the loss of active metallic silver, they can significantly affect catalyst performance optimization. In addition, the present invention employs a strategy of micro-silver doping to regulate the composite material. The in-situ grown micro-silver significantly optimizes the overall performance of the composite material and enhances its selectivity for carbon dioxide reduction.

[0072] The load amount mentioned in this invention is m Ag / (m Ag +m 镧系氧化物 )×100%. Taking Example 1 as an example, the molar ratio of Ag:Pr = 1:2, and the loading amount = 107.8682 / (107.8682+2*1021.44 / 6) = 24.05%.

[0073] Example 1 Ag / Pr6O 11 Catalyst preparation

[0074] Figure 1 The process for catalyst preparation is demonstrated.

[0075] Weigh out 4.3501 g of Pr(NO3)3·6H2O and 0.8494 g of AgNO3, respectively, and pour them into a beaker. Add an appropriate amount of deionized water and stir on a magnetic stirrer until the solution is clear and transparent. Mix 5.84 g of ethylenediaminetetraacetic acid, 8.41 g of citric acid monohydrate, and 40 mL of ammonia water and stir until completely dissolved. Pour the mixture into the aforementioned beaker to prepare a complex solution. Heat the solution at 100 °C with continuous stirring until it becomes a gel. Place the gel mixture in a 180 °C electric hot air drying oven and dry for 8 hours to obtain a black, fluffy solid precursor. Place a portion of the precursor in a muffle furnace under air atmosphere and heat to 800 °C at a rate of 4 °C / min, and hold for 2 hours. After natural cooling, remove and grind to obtain the final product, labeled Ag / Pr6O. 11 .

[0076] Example 2 Preparation of Ag / La2O3 catalyst

[0077] Weigh out 4.3301 g of La(NO3)3·6H2O and 0.8494 g of AgNO3, respectively, and pour them into a beaker. Add an appropriate amount of deionized water and stir on a magnetic stirrer until clear and transparent. Mix 5.84 g of ethylenediaminetetraacetic acid, 8.41 g of citric acid monohydrate, and 40 mL of ammonia water and stir until completely dissolved. Pour this mixture into the aforementioned beaker to prepare a complex solution. Heat the solution at 100 °C with continuous stirring until it becomes a gel. Place the gel mixture in a 180 °C electric hot air drying oven and dry for 8 hours to obtain a black, fluffy solid precursor. Place a portion of the precursor in a muffle furnace under air atmosphere and heat to 800 °C at a rate of 4 °C / min, and hold for 2 hours. After natural cooling, remove and grind to obtain the final product, labeled Ag / La2O3.

[0078] Example 3 Preparation of Ag / CeO2 catalyst

[0079] Weigh out 4.3422 g of Ce(NO3)3·6H2O and 0.8494 g of AgNO3, respectively, and pour them into a beaker. Add an appropriate amount of deionized water and stir on a magnetic stirrer until clear and transparent. Mix 5.84 g of ethylenediaminetetraacetic acid, 8.41 g of citric acid monohydrate, and 40 mL of ammonia water and stir until completely dissolved. Pour the mixture into the aforementioned beaker to prepare a complex solution. Heat the solution at 100 °C with continuous stirring until it becomes a gel. Place the gel mixture in a 180 °C electric hot air drying oven and dry for 8 hours to obtain a black, fluffy solid precursor. Place a portion of the precursor in a muffle furnace under air atmosphere and heat to 800 °C at a rate of 4 °C / min, and hold for 2 hours. After natural cooling, remove and grind to obtain the final product, labeled Ag / CeO2.

[0080] Example 4: Preparation of Ag / Nd2O3 catalyst

[0081] Weigh out 4.3885 g of Nd(NO3)3·6H2O and 0.8494 g of AgNO3, respectively, and pour them into a beaker. Add an appropriate amount of deionized water and stir on a magnetic stirrer until clear and transparent. Mix 5.84 g of ethylenediaminetetraacetic acid, 8.41 g of citric acid monohydrate, and 40 mL of ammonia water and stir until completely dissolved. Pour this mixture into the aforementioned beaker to prepare a complex solution. Heat the solution at 100 °C with continuous stirring until it becomes a gel. Place the gel mixture in a 180 °C electric hot air drying oven and dry for 8 hours to obtain a black, fluffy solid precursor. Take a portion of the precursor and place it in a muffle furnace under air atmosphere. Heat the temperature to 800 °C at a rate of 4 °C / min and hold for 2 hours. After natural cooling, remove and grind to obtain the final product, labeled Ag / Nd2O3.

[0082] Comparative Example 1Pr6O 11 Catalyst preparation

[0083] Weigh 4.3501 g of Pr(NO3)3·6H2O and pour it into a beaker. Add an appropriate amount of deionized water and stir on a magnetic stirrer until clear and transparent. Mix 5.84 g of ethylenediaminetetraacetic acid, 8.41 g of citric acid monohydrate, and 40 mL of ammonia water and stir until completely dissolved. Pour this mixture into the aforementioned beaker to prepare a complex solution. Heat the solution at 100°C with continuous stirring until it becomes a gel. Place the gel mixture in a 180°C electric drying oven and dry for 8 hours to obtain a black, fluffy solid precursor. Place a portion of the precursor in a muffle furnace under air atmosphere and heat to 800°C at a rate of 4°C / min, holding for 2 hours. After natural cooling, remove and grind to obtain the final product, labeled as Pr6O. 11 .

[0084] Preparation of Comparative Example 2: Ag powder catalyst

[0085] Weigh 0.8494 g of AgNO3 and pour it into a beaker. Add an appropriate amount of deionized water and stir on a magnetic stirrer until clear and transparent. Mix 5.84 g of ethylenediaminetetraacetic acid, 8.41 g of citric acid monohydrate, and 40 mL of ammonia water and stir until completely dissolved. Pour this mixture into the aforementioned beaker to prepare a complex solution. Heat the solution at 100 °C with continuous stirring until it becomes a gel. Place the gel-like mixture in a 180 °C electric drying oven and dry for 8 hours to obtain a black, fluffy solid precursor. Place a portion of the precursor in a muffle furnace under air atmosphere and heat to 800 °C at a rate of 4 °C / min, holding for 2 hours. After natural cooling, remove and grind to obtain the final product, labeled as Ag powder.

[0086] Comparative example 3Ag+Pr6O 11 Catalyst preparation

[0087] A certain amount of Pr6O from Comparative Example 1 was weighed out according to a mass ratio of 7:3. 11 The Ag from Example 1 and Comparative Example 2 were physically ground and mixed, then placed in a muffle furnace under air atmosphere, heated to 800°C at a rate of 4°C / min and held for 2 hours to obtain the target product. Schematic diagrams of the sample structures from Example 1 and Comparative Example 3, obtained through both chemical and physical synthesis methods, are shown below. Figure 2 As shown.

[0088] XRD characterization of materials

[0089] The Ag / Pr6O of Example 1 of this invention 11 Pr6O and Comparative Examples 1, 2, and 3 11 Ag powder, Ag+Pr6O 11 The XRD (X-ray diffraction) results are as follows Figure 3 As shown, the synthesized Ag / Pr6O 11 and Ag+Pr6O 11 Both are Ag and Pr6O 11 A two-phase composite material. Specifically, within the diffraction angle range of 20-30 degrees, Ag+Pr6O... 11 Compared to Pr6O 11 The peak position of Ag / Pr6O has a slight shift. 11 Compared to Pr6O 11 The significant shift in peak position indicates cell expansion of the support in the chemically synthesized composite material. This suggests that some silver elements were incorporated into the oxide cell during synthesis, leading to stronger interactions between the two phases in the composite material. The XRD results for Examples 2, 3, and 4 are as follows: Figure 4 As shown in the figures, the results all demonstrate the successful synthesis of silver / lanthanide oxide composite materials, further proving the universality of the preparation method described in this invention.

[0090] Evaluation of carbon dioxide electroreduction performance

[0091] Electrode slurry preparation. 10 mg of the catalyst prepared in the examples or comparative examples, 10 mg of conductive carbon black (a conductive agent with almost no catalytic performance), 1 mL of ethanol (a dispersant), and 100 μL of Nafion solution (wt 5%) were thoroughly ultrasonically mixed to form a uniform black ink-like slurry. The slurry was drop-coated onto the surface of a glassy carbon electrode and allowed to air dry naturally to serve as the working cathode electrode.

[0092] The prepared catalyst electrode was used as the cathode working electrode, with silver-silver chloride as the reference electrode and a platinum sheet as the counter electrode, forming a three-electrode system for testing the carbon dioxide electroreduction performance in an H-type electrolytic cell. The anode and cathode electrolytic cells were separated by a Nafion proton exchange membrane, both filled with 0.1M KHCO3 electrolyte. During the test, CO2 was passed into the electrolyte until saturation, followed by constant potential electrolysis testing. The optimal potential was -1.2V (VS RHE), and the optimal mass-active current density was 48.4Ag. -1 The gaseous products obtained were analyzed by gas chromatography. At the same time, the catalyst was recovered from the cathode working electrode after the reaction was completed, which is the post-reaction sample (-AF).

[0093] 1. XPS, EPR, SEM, and TEM characterization of materials

[0094] The following sample after the reaction is the cathode working electrode after testing the carbon dioxide electroreduction performance.

[0095] Figure 5 Ag / Pr6O was demonstrated 11 and Ag / Pr6O 11 The sample after the reaction (Ag / Pr6O) 11 XPS (X-ray photoelectron spectroscopy) of praseodymium oxide (-AF) revealed that some Ag elements were indeed successfully doped into praseodymium oxide, and were rapidly and completely reduced to elemental Ag during the reaction. Figure 6 Pr6O was demonstrated 11 Ag+Pr6O 11 Ag / Pr6O 11 and Ag / Pr6O 11 The sample after the reaction (Ag / Pr6O) 11 XPS results for O element (-AF) show Ag / Pr6O 11 The oxygen defect concentration was the highest compared to the comparative example, and this ratio increased further after the reaction. Figure 7 The EPR (electron paramagnetic resonance) results of four samples were presented, which also proved the Ag / Pr6O 11 and Ag / Pr6O 11 The sample after the reaction (Ag / Pr6O) 11 -AF) has the highest oxygen defect concentration.

[0096] Figure 8 Ag / Pr6O was demonstrated 11 The SEM (scanning electron microscope) results of the samples after the electrochemical reaction show that the morphology of the samples before and after the reaction is not significantly different; they are all uniform spherical nanoparticles. However, due to the electrochemical treatment and the above... Figure 5The in-situ precipitation process mentioned above further reduces the average particle size distribution of the catalyst after the reaction, which is beneficial to the catalytic process. Figure 9 Further observation of the TEM (transmission electron microscopy) results revealed that Ag / Pr6O 11 The nanospheres have a diameter of approximately 100 nm. Further high-resolution transmission electron microscopy tests also showed that the lattice fringes of the two-phase material contained in the nanospheres matched well with the lattice fringes of praseodymium oxide and silver, and the two-phase diameters exhibited a relatively rich two-phase interface, proving that there is an interaction between the metal and the support in the composite material.

[0097] 2. Carbon dioxide electroreduction performance

[0098] Figure 10 This invention demonstrates the Ag / Pr6O 11 The catalytic performance of the catalysts in Comparative Examples 1, 2, and 3. For example... Figure 10 As shown in Figure a, at a voltage of -1.2V, Ag / Pr6O 11 The normalized mass activity was 48.4 Ag. -1 It is much larger than the comparative Ag and Ag+Pr6O. 11 This indicates that the reactivity of the composite phase prepared by chemical methods is significantly enhanced. Figure 10 In b, Pr6O 11 It exhibits almost no catalytic performance, Ag / Pr6O 11 Compared to Ag and Ag+Pr6O 11 The CO selectivity is significantly improved, with a Faradaic efficiency of up to 97% at -1.0V and 98% at -1.2V, achieving high CO selectivity over a wide operating range, while the hydrogen evolution side reaction is significantly suppressed. Furthermore, in Figure 11 It can be seen from this that Ag / Pr6O 11 During the carbon dioxide reduction reaction, the catalyst maintains a Faraday efficiency of over 90% for CO for approximately 30 hours, indicating good operational stability. Figure 12 The ECSA (electrochemical active area) indicates that Ag / Pr6O 11 Compared to Ag and Ag+Pr6O 11 It has a high effective surface area for electrochemical reactions. Figure 13 The EIS (electrochemical impedance spectroscopy) results also indicate that Ag / Pr6O 11 Compared to Ag and Ag+Pr6O 11 It exhibits low electrochemical impedance, demonstrating a fast charge transfer rate and extended mass transfer process.

[0099] Figure 14The electrochemical results of carbon dioxide reduction using Ag / La₂O₃, Ag / CeO₂, and Ag / Nd₂O₃ in Examples 2, 3, and 4 are presented. The extended application examples all achieve a Faradaic efficiency of over 90% for CO, demonstrating the general superiority of the preparation method of this invention and its applicability to other oxide systems. These results prove that this invention has certain industrial application value.

[0100] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing a supported Ag / lanthanide oxide nanocomposite material, characterized in that, Ag is supported on a lanthanide oxide, wherein the lanthanide oxide is Pr6O. 11 The Ag loading in the composite material is 20-25 wt%. The preparation method of the supported Ag / lanthanide oxide nanocomposite material includes: (1) Dissolve lanthanide nitrates and silver nitrates in water to obtain a solution; (2) Add a metal ion complexing agent to the obtained solution, adjust the pH to 6.5-7.5, and heat and stir to form a gel-like mixture; (3) The obtained gel-like mixture is heated and dried to obtain precursor powder; the obtained precursor powder is calcined to obtain the composite material; In step (1), the lanthanide nitrate is praseodymium nitrate.

2. The preparation method according to claim 1, characterized in that, The particle size of the composite material is 50-200 nm.

3. The preparation method according to claim 1, characterized in that, In step (1), the molar ratio of the lanthanide nitrate to silver nitrate is 1:1-4.

4. The preparation method according to claim 1, characterized in that, In step (2), the metal ion complexing agent is ethylenediaminetetraacetic acid and citric acid monohydrate; the mass ratio of silver nitrate, ethylenediaminetetraacetic acid and citric acid monohydrate is 1:5.8-7.8:8.9-10.

9.

5. The preparation method according to claim 1, characterized in that, In step (2), the temperature of the heated and stirred gel mixture is 90-110℃.

6. The preparation method according to claim 1, characterized in that, In step (3), the heating and drying temperature is 170-190℃ and the heating and drying time is 7-10h.

7. The preparation method according to claim 1, characterized in that, In step (3), the calcination temperature is 500-900℃ and the calcination time is 1-3h.

8. An electrode, characterized in that, Made from a composite material produced by the method described in any one of claims 1-7.

9. The electrode according to claim 8, characterized in that, The composite material is used as a catalyst, conductive agent, dispersant, and binder, and is thoroughly mixed to obtain a slurry; the obtained slurry is then dripped onto the surface of a carrier and allowed to air dry naturally.

10. The electrode according to claim 9, characterized in that, The electrode uses glassy carbon electrode or carbon fiber paper as a carrier; the conductive agent of the electrode is conductive carbon black; the dispersant of the electrode is an organic solvent; the binder of the electrode is Nafion solution or PTFE binder; the mass ratio of the composite material to the conductive agent is 1:0.5-2; the dosage ratio of the composite material, dispersant and binder is 10mg:0.7-1.2mL:90-120μL.

11. The electrode according to claim 9, characterized in that, The dispersant for the electrode is ethanol or isopropanol; the mass ratio of the composite material to the conductive agent is 1:0.7-1.

2.

12. Use of the electrode according to any one of claims 8-11 as a cathode working electrode in an electrochemical carbon dioxide reduction reaction.

13. The use according to claim 12, characterized in that, The electrochemical carbon dioxide reduction reaction employs a three-electrode system, with the composite material serving as the cathode working electrode, silver-silver chloride as the reference electrode, and a platinum sheet or graphite rod as the counter electrode.

14. The use according to claim 13, characterized in that, The electrochemical carbon dioxide reduction reaction is carried out in an H-type electrolytic cell using a 0.01-0.2M KHCO3 solution, and the reaction is saturated with carbon dioxide gas.

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