Asymmetric oxygen-deficient copper-based perovskite oxide and application thereof in electrocatalytic carbon dioxide reduction

Abstract

The invention belongs to the field of design and development of electrocatalytic carbon dioxide reduction catalysts, and particularly relates to an asymmetric-structure oxygen-deficient copper-based perovskite oxide (an asymmetric oxygen-deficient copper-based perovskite oxide formed by corner-shared CuO5 and CuO6 motifs) and application of the asymmetric-structure oxygen-deficient copper-based perovskite oxide in preparation of C2 + products through electrocatalytic carbon dioxide reduction. The crystal structure of the catalyst is composed of an angle-shared CuO5 square pyramid and a CuO6 octahedral motif, the general formula of the catalyst is AxA '1-xCuO3-delta (x is greater than 0 and less than 1), A and A' site elements are different selected from lanthanide metal or alkaline earth metal elements, and delta is oxygen vacancy. Through the asymmetric site structure of CuO5-CuO6, the catalyst provided by the invention realizes differential adsorption and hydrogenation reaction of * CO intermediates, promotes asymmetric * CO-* CHO coupling, and improves the activity and selectivity of C2 + products. Through long-time tests, the catalyst still shows excellent reaction performance, is suitable for renewable energy source driven CO2 electro-catalytic conversion application, and is beneficial to realizing efficient carbon resource recycling.

Description

Technical Field

[0001] The present invention belongs to the field of design and development of electrocatalytic carbon dioxide reduction catalysts, and specifically relates to an asymmetric oxygen-deficient copper-based perovskite oxide (an asymmetric oxygen-deficient copper-based perovskite oxide composed of corner-shared CuO5 and CuO6 motifs) and its application in electrocatalytic carbon dioxide reduction to C 2+ Application in products. Background Art

[0002] Renewable electricity-driven electrocatalytic carbon dioxide reduction (CO2RR) can convert carbon dioxide into high-value-added chemicals and fuels, and is a potential way to achieve a carbon-neutral cycle. 2+ Products such as ethylene (C2H4) and ethanol (C2H5OH) have attracted much attention due to their high market economic value, high energy density and wide industrial application. Cu-based catalysts have moderate *CO and *H adsorption energies, which can stabilize *CO intermediates and promote their subsequent hydrogenation or CC coupling reactions. They are almost the only catalyst that can deeply reduce CO2 to C 2+ However, due to the complex multi-electron-proton transfer steps and structural degradation problems, Cu-based catalysts still face the problem of C 2+ The product's unsatisfactory activity, selectivity, and poor stability limit its industrial application. Therefore, it is necessary to develop and design efficient and stable Cu-based electrocatalysts to realize the conversion of CO2 to C 2+ The resource utilization of products is of great significance. Summary of the Invention

[0003] The purpose of this invention is to improve the existing copper-based catalyst CO2RR production of C 2+ The present invention provides a novel asymmetric oxygen-deficient copper-based perovskite oxide (an asymmetric oxygen-deficient copper-based perovskite oxide composed of corner-shared CuO5 and CuO6 motifs) and its application in electrocatalytic carbon dioxide reduction to C 2+ Application in products.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions:

[0005] An asymmetric oxygen-deficient copper-based perovskite oxide, the crystal structure of which is composed of an orderly arrangement of corner-sharing CuO5 square pyramids and CuO6 octahedral motifs, forming an asymmetric Cu-Cu site.

[0006] The general structural formula of the asymmetric oxygen-deficient copper-based perovskite oxide is A x A' 1-x CuO 3-δ(0<x<1), wherein the elements at positions A and A' are different and are selected from lanthanide metals or alkaline earth metals (i.e., when A is selected from lanthanide metals, A' is selected from alkaline earth metals; when A is selected from alkaline earth metals, A' is selected from lanthanide metals), and δ is an oxygen defect.

[0007] The lanthanide metals include La, Ce, Pr, Nd, Sm, etc.; the alkaline earth metal elements include Sr, Ba, etc.

[0008] The A and A'-site elements are orderly arranged in the gaps of the CuO5 square pyramids and / or CuO6 octahedral motifs; the oxygen defects coexist with the CuO5 square pyramids and are arranged in an orderly manner.

[0009] A method for preparing the asymmetric oxygen-deficient copper-based perovskite oxide according to claim 1,

[0010] A. Weigh the oxides or carbonates containing the raw material elements according to the stoichiometric ratio, add ethanol, and mix them evenly by ball milling in a high-energy ball mill;

[0011] B. After drying the above mixture, place it in a muffle furnace and repeatedly calcine it at 800-1200℃ for 5-12h until pure phase A is obtained. x A' 1-x CuO 3-δ (0<x<1)Perovskite.

[0012] A method for preparing the asymmetric oxygen-deficient copper-based perovskite oxide,

[0013] A. Weigh the nitrate of the corresponding element or other soluble salt that does not introduce impurities according to the stoichiometric ratio, add deionized water, and stir continuously to dissolve it evenly;

[0014] B. Add EDTA and citric acid to the above solution and continue stirring until dissolved; wherein the molar ratio of EDTA and citric acid to total metal ions is 1:1.5:1;

[0015] C. adjusting the pH value of the mixed solution to 9 and continuing stirring for 12 hours to form a transparent sol precursor;

[0016] D. Dry the above sol precursor to obtain a powder precursor, and repeatedly calcine at 800-1200℃ until pure phase A is obtained. x A' 1-x CuO 3-δ Perovskite oxides.

[0017] The pure phase A was obtained x A' 1-x CuO 3-δ (0<x<1) The perovskite is ball-milled again to obtain a powder sample with a smaller particle size.

[0018] The ball milling is carried out using a high-energy ball mill under the following conditions: the ball milling time is 3-5 hours and the rotation speed is 900-1400 rpm.

[0019] The sol precursor is placed in an oven and heated at 250° C. for 8-12 hours to form a powder precursor.

[0020] An application of the asymmetric oxygen-deficient copper-based perovskite oxide, and an application of the asymmetric oxygen-deficient copper-based perovskite oxide as a catalyst in an electrocatalytic carbon dioxide reaction.

[0021] The oxygen-deficient copper-based perovskite oxide is used as a catalyst in the electrocatalytic reduction of carbon dioxide to produce C 2+ Application in products.

[0022] During use, the catalyst is a liquid-phase catalyst obtained by uniformly mixing the copper-based perovskite oxide powder with a solution by ultrasonic mixing; wherein 1 mg of powder is added to 100-150 μL of a dispersion, and the dispersion is an alcohol solution containing Nafion.

[0023] The volume ratio of Nafion to alcohol in the Nafion-containing alcohol solution is 1:20; the alcohol is ethanol or isopropanol.

[0024] A method for preparing C from carbon dioxide by electrocatalysis 2+ The method for producing a product, using the oxygen-deficient copper-based perovskite oxide as a catalyst to electrocatalyze carbon dioxide reduction to produce C 2+ product.

[0025] The present invention relates to the following principles:

[0026] Perovskite oxides have the advantages of rich chemical composition, diverse crystal electronic structure, and adjustable physicochemical properties, and have the potential to develop into high-performance electrocatalysts. Usually, the chemical formula of perovskite oxides is ABO3, and its crystal structure is composed of corner-sharing BO6 octahedral chains and 12-coordinated A-site cations. Among them, the A-site cations occupy the position of the octahedral gap. Usually, the properties of the BO6 group or the characteristics of the BO bond fundamentally determine the electrocatalytic performance of perovskite oxides. Taking into account the characteristics of copper-based catalysts and perovskite oxides, if the Cu element occupies the B position of the perovskite, then by optimizing the relevant physicochemical properties, the resulting copper-based perovskite oxide is expected to exhibit excellent electroreduction of CO2 to C 2+ However, based on C 2+ Product formation mechanism, copper-based perovskite oxides to C 2+ The activity and selectivity of the product are severely limited by its intrinsic structural properties. 2+The formation of products mainly depends on the formation of CC bonds, and its main pathways include symmetric CC coupling (such as *CO-*CO dimerization) and asymmetric CC coupling (such as *CO-*CHO dimerization). However, the distance between adjacent Cu-Cu sites in perovskite oxides is too far, which is not conducive to the occurrence of symmetric CC coupling; perovskite oxides are composed of uniform CuO6 octahedral chains, and their symmetric charge distribution cannot achieve differential adsorption of key intermediates *CO and *CHO, reducing the possibility of asymmetric CC coupling. Based on the fact that asymmetric coupling has more thermodynamic and kinetic advantages than symmetric coupling, designing copper-based perovskite oxides with unique structures to enhance their asymmetric CC coupling is a key way to improve their electrocatalytic CO2 reduction to C 2+ An effective way to improve product performance.

[0027] The crystal structure of the asymmetric oxygen-deficient copper-based perovskite oxide described in the present invention is composed of a corner-shared CuO5-CuO6 motif. This structure forms asymmetric Cu-Cu sites with different electronic structures within the perovskite, disrupting the inherent symmetrical charge distribution of CuO6-motif copper-based perovskites. This facilitates the differentiated adsorption of *CO intermediates, thereby promoting asymmetric C-C coupling reactions. Furthermore, because the corner-shared CuO5-CuO6 motif exhibits a globally ordered distribution within the copper-based perovskite oxide, the asymmetric Cu-Cu sites constructed possess a well-defined configuration and sufficient density, helping to balance the coverage and spatial distribution of *CO and *CHO (or *COH) intermediates, suppressing their random migration, thereby preventing their re-adsorption or escape at inappropriate sites and ensuring an optimal platform for asymmetric C-C coupling reactions.

[0028] Beneficial effects

[0029] Regarding the current copper-based catalyst CO2RR to C 2+ To solve the problem of unsatisfactory product activity and selectivity and poor stability, the present invention proposes an asymmetric oxygen-deficient copper-based perovskite oxide catalyst composed of a corner-sharing CuO5-CuO6 motif, aiming to significantly improve its catalytic performance by regulating the local Cu coordination environment (oxygen coordination type), constructing an asymmetric Cu-Cu site, and optimizing the asymmetric CC coupling; at the same time, utilizing the covalent nature of the Cu-O bond to improve the long-term stability of the catalyst. Specifically: ① Thanks to the inherent advantages of copper-based perovskite oxides (rich chemical composition, diverse crystal electronic structure, adjustable physicochemical properties, etc.), by regulating the physicochemical properties related to the CuO6 octahedron and / or Cu-O bond, it is expected to obtain good C 2+② The corner-sharing CuO5-CuO6 motif is orderly arranged in the copper-based perovskite crystal structure to form asymmetric Cu-Cu sites, which causes charge rearrangement and promotes the differential adsorption of *CO and *CHO intermediates, thereby promoting asymmetric CC coupling; ③ The strong covalency of the Cu-O bond is utilized to stabilize the Cu-O lattice, inhibit the collapse of the catalyst structure, and improve the catalyst stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The La prepared in Example 1 0.8 Ba 0.2 CuO 3-δ XRD patterns

[0031] Figure 2 The La prepared in Example 1 0.8 Ba 0.2 CuO 3-δ Crystal structure model diagram

[0032] Figure 3 The La prepared in Example 1 0.8 Ba 0.2 CuO 3-δ CO2RR product distribution diagram

[0033] Figure 4 The CuO CO2RR product distribution diagram of the comparative sample prepared in Example 1

[0034] Figure 5 The La prepared in Example 1 0.8 Ba 0.2 CuO 3-δ In situ infrared spectroscopy

[0035] Figure 6 The La prepared in Example 1 0.8 Ba 0.2 CuO 3-δ Comparison of CO2RR operation stability with the control sample CuO DETAILED DESCRIPTION

[0036] The specific embodiments of the present invention are further described below with reference to examples. It should be noted that the specific embodiments described this time are only for illustrating and explaining the present invention, and are not intended to limit the present invention.

[0037] Example 1

[0038] The material La of the present invention was prepared by sol-gel method 0.8 Ba 0.2 CuO 3-δ For CO2RR example:

[0039] Commercially available La(NO3)3·6H2O, Ba(NO3)2, and Cu(NO3)2·3H2O were dissolved in deionized water in a stoichiometric ratio as raw materials and stirred evenly. Citric acid and EDTA were added to the mixed solution at a molar ratio of 1.5:1:1 to all metal ions in the raw materials. After all the raw materials were dissolved, ammonia water was added to adjust the pH to 9. The precursor solution was heated and stirred for more than 10 hours until a transparent sol was obtained. The sol precursor was placed in an oven and heated at 250°C for 10 hours to form a powder precursor. The powder precursor was then calcined at 950°C for 5 hours to obtain La 0.8 Ba 0.2 CuO 3-δ Powder. 0.8 Ba 0.2 CuO 3-δ The powder was ball-milled at 1400 rpm for 5 h to obtain the powder catalyst. 0.8 Ba 0.2 CuO 3-δ The crystal structure is a P4 / m tetragonal structure composed of corner-sharing CuO5 square pyramids and CuO6 octahedra arranged in an orderly manner. La ions and Ba ions are orderly filled in the gaps of the CuO5-CuO6 motif. Oxygen vacancies coexist with the CuO5 square pyramids and are located at the bottom of the CuO5 square pyramids, corresponding to the distribution of oxygen ions at the top (such as Figure 1 , Figure 2 shown);

[0040] In addition, CuO was ball-milled at 1400 rpm for 5 h to obtain a comparative sample CuO powder catalyst.

[0041] The performance test of the catalyst obtained above was carried out:

[0042] 1) Electrocatalytic performance test:

[0043] La 0.8 Ba 0.2 CuO 3-δ Powder and CuO powder were mixed with ethanol / Nafion mixed solution to prepare catalyst dispersion, and electrocatalytic carbon dioxide reduction test was carried out, specifically:

[0044] A. will La 0.8 Ba 0.2 CuO 3-δ The powder and CuO powder were mixed with ethanol and Nafion solution at a ratio of 1 mg: 100 μL: 5 μL, respectively, to prepare a catalyst dispersion, and then ultrasonically mixed for 30 min.

[0045] B. Coating the uniformly dispersed liquid catalyst on the surface of the hydrophobic carbon paper, followed by drying.

[0046] C. Place the catalyst-coated carbon paper in a three-electrode flow electrolysis cell. The reference electrode is Ag / AgCl, the working electrode is the catalyst-loaded carbon paper, and the counter electrode is a Pt mesh. An 8 mol / L KOH solution is used as the electrolyte, circulated to the anode and cathode chambers of the electrolysis cell via a peristaltic pump. The anode and cathode chambers are separated by an anion exchange membrane to prevent cross-contamination.

[0047] D. CO2 gas is introduced into the gas chamber of the flow electrolytic cell. After power is applied, the electrocatalytic CO2 reduction reaction occurs on the catalyst surface and at the three-phase interface between the catalyst, CO2 and the electrolyte.

[0048] Depend on Figure 3 and Figure 4 It can be seen that La 0.8 Ba 0.2 CuO 3-δ of and FE C2+ Significantly higher than CuO. Within the applied current density range, La 0.8 Ba 0.2 CuO 3-δ of and FE C2+ At 400mA cm -2 The current density can reach up to 60% and 85%, and the maximum can reach CuO and 2.9 times of the original At the same time, compared with other reported Cu-based perovskites (such as La2CuO4 and other typical Cu-based perovskites, No more than 55%) compared to La 0.8 Ba 0.2 CuO 3-δ FE C2+ It also has obvious advantages. 0.8 Ba 0.2 CuO 3-δ Compared with CuO and other Cu-based perovskites, it has better C 2+ The main reason for the activity and selectivity of the product is that its corner-shared CuO5 and CuO6 motifs induce differential *CO adsorption and hydrogenation, thereby synergistically promoting asymmetric CC coupling. 0.8 Ba 0.2 CuO 3-δ In the catalyst, C 2+ The potential reaction pathway for the product is *CO-*CHO asymmetric coupling ( Figure 5 ).

[0049] 2) Catalyst stability test:

[0050] The catalyst prepared above was heated at 200 mA cm -2 The stability of the catalyst was tested at the current density ( Figure 6 ). Thanks to the strong covalent nature of the Cu-O bond, La 0.8 Ba 0.2 CuO 3-δ It can operate stably in alkaline electrolyte (1M KOH) for ~23h. It is stable at around 46% with no significant performance degradation. It remains at around 11% without any significant increase. However, after 6h of electrolysis, the CuO sample and They show obvious downward and upward trends, respectively, indicating that CuO has been reconstructed.

[0051] Example 2

[0052] The material La of the present invention was prepared by sol-gel synthesis method 0.5 Ba 0.5 CuO 3-δ For CO2RR example:

[0053] Dissolve commercially available La(NO3)3·6H2O, Ba(NO3)2, and Cu(NO3)2·3H2O in deionized water in a stoichiometric ratio and stir evenly. Add citric acid and EDTA to the mixed solution at a molar ratio of 1.5:1:1 to all metal ions. After all raw materials are dissolved, add ammonia water to adjust the pH to 9. Heat and stir the precursor solution for 12 hours until a transparent sol is obtained. Place the sol precursor in an oven and heat it at 250°C for 10 hours to form a powder precursor. Then calcine the powder precursor at 900°C for 6 hours to obtain La 0.5 Ba 0.5 CuO 3-δ Powder. 0.5 Ba 0.5 CuO 3-δ The powder was ball-milled at 1400 rpm for 5 h to obtain a powder catalyst.

[0054] According to the catalytic performance test record process in Example 1 above, La 0.5 Ba 0.5 CuO 3-δ The powder was mixed with ethanol and Nafion solution at a ratio of 1 mg: 120 μL: 5 μL to prepare a catalyst dispersion. The electrocatalytic carbon dioxide reduction test was carried out. The perovskite catalyst material had good CO2RR performance at 400 mA cm -2 Under the test conditions of current density and 8M KOH, and They can reach 54% and 76% respectively.

[0055] At the same time, the stability of the catalyst was tested at 200 mA cm -2 The stability of the catalyst was tested under different current densities, and the catalyst could operate stably for more than 20 hours.

[0056] Example 3

[0057] The material Pr of the present invention was prepared by sol-gel synthesis method. 0.8 Sr 0.2 CuO 3-δ For CO2RR example:

[0058] Dissolve commercially available Pr(NO3)3·6H2O, Sr(NO3)2, and Cu(NO3)2·3H2O in deionized water in a stoichiometric ratio and stir evenly. Add citric acid and EDTA to the mixed solution at a molar ratio of 1.5:1:1 to all metal ions. After all raw materials are dissolved, add ammonia water to adjust the pH to 9. Heat and stir the precursor solution for 12 hours until a transparent sol is obtained. Place the sol precursor in an oven and heat it at 250°C for 10 hours to form a powder precursor. Then calcine the powder precursor at 950°C for 6 hours to obtain Pr 0.8 Sr 0.2 CuO 3-δ Powder. 0.8 Sr 0.2 CuO 3-δ The powder was ball-milled at 1400 rpm for 5 h to obtain a powder catalyst.

[0059] According to the catalytic performance test record process in Example 1 above, Pr 0.8 Sr 0.2 CuO 3-δ The powder was mixed with ethanol and Nafion solution at a ratio of 1 mg: 100 μL: 5 μL to prepare a catalyst dispersion for electrocatalytic carbon dioxide reduction test. The perovskite catalyst material has good CO2RR performance at 400 mA cm -2 Under the test conditions of current density and 8M KOH, and They can reach 56% and 80% respectively.

[0060] At the same time, the stability of the catalyst was tested at 200 mA cm -2 The catalyst was tested for stability under different current densities and the catalyst was found to be able to operate stably for more than 18 hours.

[0061] Example 4

[0062] The material Pr of the present invention was prepared by sol-gel synthesis method. 0.7 Ba 0.3CuO 3-δ For CO2RR example:

[0063] Dissolve commercially available Pr(NO3)3·6H2O, Ba(NO3)2, and Cu(NO3)2·3H2O in deionized water in a stoichiometric ratio and stir evenly. Add citric acid and EDTA to the mixed solution at a molar ratio of 1.5:1:1 to all metal ions. After all raw materials are dissolved, add ammonia water to adjust the pH to 9. Heat and stir the precursor solution for 10 hours until a transparent sol is obtained. Place the sol precursor in an oven and heat it at 250°C for 12 hours to form a powder precursor. Then calcine the powder precursor at 950°C for 5 hours to obtain Pr 0.7 Ba 0.3 CuO 3-δ Powder. 0.7 Ba 0.3 CuO 3-δ The powder was ball-milled at 1400 rpm for 5 h to obtain a powder catalyst.

[0064] According to the catalytic performance test record process in Example 1 above, Pr 0.7 Ba 0.3 CuO 3-δ The powder was mixed with ethanol and Nafion solution at a ratio of 1 mg: 100 μL: 5 μL to prepare a catalyst dispersion for electrocatalytic carbon dioxide reduction test. The perovskite catalyst material has good CO2RR performance at 400 mA cm -2 Under the test conditions of current density and 8M KOH, and They can reach 54% and 78% respectively.

[0065] At the same time, the stability of the catalyst was tested at 200 mA cm -2 The catalyst was tested for stability under different current densities and the catalyst was found to be able to operate stably for more than 15 hours.

[0066] Example 5

[0067] The material Nd was prepared by sol-gel synthesis method. 0.8 Ba 0.2 CuO 3-δ For CO2RR example:

[0068] Dissolve commercially available Nd(NO3)3·6H2O, Ba(NO3)2, and Cu(NO3)2·3H2O in deionized water in a stoichiometric ratio and stir evenly. Add citric acid and EDTA to the mixed solution at a molar ratio of 1.5:1:1 to all metal ions. After all the raw materials are dissolved, add ammonia water to adjust the pH to 9. Heat and stir the precursor solution for 12 hours until a transparent sol is obtained. Place the sol precursor in an oven and heat it at 250°C for 10 hours to form a powder precursor. Then calcine the powder precursor at 900°C for 5 hours to obtain Nd 0.8 Ba 0.2 CuO 3-δ Powder. 0.8 Ba 0.2 CuO 3-δ The powder was ball-milled at 1400 rpm for 5 h to obtain a powder catalyst.

[0069] According to the catalytic performance test process described in Example 1, Nd 0.8 Ba 0.2 CuO 3-δ The powder was mixed with ethanol and Nafion solution at a ratio of 1 mg: 100 μL: 5 μL to prepare a catalyst dispersion for electrocatalytic carbon dioxide reduction test. The perovskite catalyst material has good CO2RR performance at 400 mA cm -2 Under the test conditions of current density and 8M KOH, and They can reach 50% and 82% respectively.

[0070] At the same time, the stability of the catalyst was tested at 200 mA cm -2 The catalyst was tested for stability under different current densities and the catalyst could operate stably for more than 17 hours.

[0071] Example 6

[0072] The material Sm of the present invention was prepared by sol-gel synthesis method. 0.9 Sr 0.1 CuO 3-δ For CO2RR example:

[0073] Dissolve commercially available Sm(NO3)3·6H2O, Sr(NO3)2, and Cu(NO3)2·3H2O in deionized water in a stoichiometric ratio and stir evenly. Add citric acid and EDTA to the mixed solution at a molar ratio of 1.5:1:1 to all metal ions. After all the raw materials are dissolved, add ammonia water to adjust the pH to 9. Heat and stir the precursor solution for 12 hours until a transparent sol is obtained. Place the sol precursor in an oven and heat it at 250°C for 10 hours to form a powder precursor. Then calcine the powder precursor at 950°C for 5 hours to obtain Sm 0.9 Sr 0.1 CuO 3-δ Powder. 0.9 Sr 0.1 CuO 3-δ The powder was ball-milled at 1400 rpm for 5 h to obtain a powder catalyst.

[0074] According to the catalytic performance test record process in Example 1 above, Sm 0.9 Sr 0.1 CuO 3-δ The powder was mixed with ethanol and Nafion solution at a ratio of 1 mg: 100 μL: 5 μL to prepare a catalyst dispersion for electrocatalytic carbon dioxide reduction test. The perovskite catalyst material has good CO2RR performance at 400 mA cm -2 Under the test conditions of current density and 8M KOH, and They can reach 57% and 78% respectively.

[0075] At the same time, the stability of the catalyst was tested at 200 mA cm -2 The catalyst was tested for stability under different current densities and the catalyst was found to be able to operate stably for more than 15 hours.

[0076] Example 7

[0077] The material Gd of the present invention was prepared by sol-gel synthesis method 0.9 Ba 0.1 CuO 3-δ For CO2RR example:

[0078] Dissolve commercially available Gd(NO3)3·6H2O, Ba(NO3)2, and Cu(NO3)2·3H2O in deionized water in a stoichiometric ratio and stir evenly. Add citric acid and EDTA to the mixed solution at a molar ratio of 1.5:1:1 to all metal ions. After all raw materials are dissolved, add ammonia water to adjust the pH to 9. Heat and stir the precursor solution for 12 hours until a transparent sol is obtained. Place the sol precursor in an oven and heat it at 250°C for 10 hours to form a powder precursor. Then calcine the powder precursor at 950°C for 5 hours to obtain Gd 0.9 Ba 0.1 CuO 3-δ Powder. Gd 0.9 Ba 0.1 CuO 3-δ The powder was ball-milled at 1400 rpm for 5 h to obtain a powder catalyst.

[0079] According to the catalytic performance test process described in Example 1, Gd 0.9 Ba 0.1 CuO 3-δ The powder was mixed with ethanol and Nafion solution at a ratio of 1 mg: 100 μL: 5 μL to prepare a catalyst dispersion for electrocatalytic carbon dioxide reduction test. The perovskite catalyst material has good CO2RR performance at 400 mA cm -2 Under the test conditions of current density and 8M KOH, and They can reach 54% and 80% respectively.

[0080] At the same time, the stability of the catalyst was tested at 200 mA cm -2 The catalyst was tested for stability under different current densities and the catalyst was found to be able to operate stably for more than 15 hours.

[0081] Example 8

[0082] The material Ce of the present invention was prepared by sol-gel synthesis method 0.7 Sr 0.3 CuO 3-δ For CO2RR example:

[0083] Dissolve commercially available Ce(NO3)3·6H2O, Sr(NO3)2, and Cu(NO3)2·3H2O in deionized water in a stoichiometric ratio and stir evenly. Add citric acid and EDTA to the mixed solution at a molar ratio of 1.5:1:1 to all metal ions. After all the raw materials are dissolved, add ammonia water to adjust the pH to 9. Heat and stir the precursor solution for 12 hours until a transparent sol is obtained. Place the sol precursor in an oven and heat it at 250°C for 10 hours to form a powder precursor. Then calcine the powder precursor at 950°C for 5 hours to obtain Ce 0.7 Sr 0.3 CuO 3-δ Powder. 0.7 Sr 0.3 CuO 3-δ The powder was ball-milled at 1400 rpm for 5 h to obtain a powder catalyst.

[0084] According to the catalytic performance test process described in Example 1, Ce 0.7 Sr 0.3 CuO 3-δ The powder was mixed with ethanol and Nafion solution at a ratio of 1 mg: 100 μL: 5 μL to prepare a catalyst dispersion for electrocatalytic carbon dioxide reduction test. The perovskite catalyst material has good CO2RR performance at 400 mA cm -2 Under the test conditions of current density and 8M KOH, and They can reach 56% and 80% respectively.

[0085] At the same time, the stability of the catalyst was tested at 200 mA cm -2 The stability of the catalyst was tested under different current densities, and the catalyst could operate stably for more than 20 hours.

Claims

1. An asymmetric oxygen-deficient copper-based perovskite oxide, characterized in that: The crystal structure of asymmetric oxygen-deficient copper-based perovskite oxides is composed of an orderly arrangement of corner-sharing CuO5 square pyramids and CuO6 octahedral motifs, forming asymmetric Cu-Cu sites.

2. The asymmetric oxygen-deficient copper-based perovskite oxide according to claim 1, characterized in that: The general structural formula of the asymmetric oxygen-deficient copper-based perovskite oxide is A x A' 1-x CuO 3-δ (0<x<1), wherein the elements at positions A and A′ are different and are selected from lanthanide metals or alkaline earth metal elements, and δ is an oxygen defect.

3. The asymmetric oxygen-deficient copper-based perovskite oxide according to claim 2, characterized in that: The lanthanide metal is La, Ce, Pr, Nd or Sm; the alkaline earth metal element is Sr or Ba.

4. The asymmetric oxygen-deficient copper-based perovskite oxide according to claim 2, characterized in that: The A and A'-site elements are orderly arranged in the gaps of the CuO5 square pyramids and / or CuO6 octahedral motifs; the oxygen defects coexist with the CuO5 square pyramids and are arranged in an orderly manner.

5. A method for preparing the asymmetric oxygen-deficient copper-based perovskite oxide according to claim 1, characterized in that: A. Weigh the oxides or carbonates containing the raw material elements according to the stoichiometric ratio, add ethanol, and mix them evenly by ball milling in a high-energy ball mill; B. After drying the above mixture, place it in a muffle furnace and repeatedly calcine it at 800-1200℃ for 5-12h until pure phase A is obtained. x A' 1-x CuO 3-δ (0<x<1)Perovskite.

6. A method for preparing the asymmetric oxygen-deficient copper-based perovskite oxide according to claim 1, characterized in that: A. Weigh the nitrate of the corresponding element or other soluble salt that does not introduce impurities according to the stoichiometric ratio, add deionized water, and stir continuously to dissolve it evenly; B. Add EDTA and citric acid to the above solution and continue stirring until dissolved; wherein the molar ratio of EDTA and citric acid to total metal ions is 1:1.5:1; C. adjusting the pH value of the mixed solution to 9 and continuing stirring for 12 hours to form a transparent sol precursor; D. Dry the above sol precursor to obtain a powder precursor, and repeatedly calcine at 800-1200℃ until pure phase A is obtained. x A' 1-x CuO 3-δ Perovskite oxides.

7. The method for preparing an asymmetric oxygen-deficient copper-based perovskite oxide according to claim 5 or 6, characterized in that: The pure phase A was obtained x A' 1-x CuO 3-δ (0<x<1) The perovskite is ball-milled again to obtain a powder sample with a smaller particle size.

8. Use of the asymmetric oxygen-deficient copper-based perovskite oxide according to claim 1, characterized in that: The oxygen-deficient copper-based perovskite oxide is used as a catalyst in the electrocatalytic carbon dioxide reaction.

9. Use of the asymmetric oxygen-deficient copper-based perovskite oxide according to claim 1, characterized in that: The oxygen-deficient copper-based perovskite oxide is used as a catalyst in the electrocatalytic reduction of carbon dioxide to produce C 2+ Application in products.

10. A method for preparing C from carbon dioxide by electrocatalysis 2+ The method for producing a product is characterized in that: Using the oxygen-deficient copper-based perovskite oxide according to claim 1 as a catalyst for electrocatalytic carbon dioxide reduction to produce C 2+ product.

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