A method for constructing nano-coral perovskite by applying transient temperature field to high-value-added carbon reduction

Abstract

The application relates to a method for constructing a nano coral perovskite by applying a transient temperature field to high-value carbon reduction, and relates to a method for preparing a perovskite by using a transient temperature field. The present application aims to solve the problems that the existing copper-based catalytic material is insufficient in active sites, poor in product selectivity, serious in hydrogen evolution reaction and needs to improve the faraday efficiency of the target product. Method: 1. preparing a precursor by a chemical bath immersion method; 2. preparing a La2CuO4 nano coral perovskite catalytic electrode based on a transient temperature field. The present application is used for constructing a nano coral perovskite by applying a transient temperature field to high-value carbon reduction.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for preparing perovskite by using a transient temperature field. BACKGROUND

[0002] The increasing carbon dioxide emissions have a serious impact on the global climate. Converting carbon dioxide into other valuable chemical products through reactions can effectively reduce the accumulation of carbon dioxide and ensure the maintenance of carbon reduction. Compared with traditional high-temperature thermal conversion, electrocatalytic carbon dioxide reduction has a higher development prospect due to its mild operating conditions. However, in the process of carbon reduction reaction, hydrogen evolution reaction is inevitable, and the reaction products are diverse. Therefore, it is of great significance to develop high-efficiency and high-selectivity carbon reduction electrodes.

[0003] In recent years, perovskite materials have been widely used in the field of optoelectronic technology. Due to its unique flexible electronic structure, perovskite exhibits a variety of unique physical and chemical properties, such as excellent carbon dioxide reduction catalytic activity. Among various commonly used catalysts for electrocatalytic carbon dioxide reduction, copper-based compounds have unique advantages in synthesizing high-value-added carbon hydrocarbons (such as methane, ethylene, etc.). However, in the actual reaction process, copper-based catalytic materials still have problems such as insufficient active sites, poor product selectivity, serious hydrogen evolution reaction, and target product Faraday efficiency to be improved. Therefore, improving the Faraday efficiency (electron utilization efficiency) of copper-based catalytic materials for single carbon hydrogen reduction product is of great significance to the research of electrocatalytic carbon reduction technology. SUMMARY

[0004] The present application aims to solve the problems of insufficient active sites, poor product selectivity, serious hydrogen evolution reaction, and target product Faraday efficiency to be improved in existing copper-based catalytic materials, and further provides a method for constructing nanocoral perovskite by using a transient temperature field for high-value-added carbon reduction.

[0005] A method for constructing nanocoral perovskite by using a transient temperature field for high-value-added carbon reduction, which is carried out according to the following steps:

[0006] I. Preparation of precursor by chemical bath immersion method:

[0007] ① Dissolve lanthanum oxide powder and copper oxide powder in nitric acid to obtain solution I;

[0008] ② Add solvent to solution I for dilution and stir uniformly to obtain solution II;

[0009] ③ Dip the conductive substrate in solution II, then take it out to obtain the precursor;

[0010] II. Preparation of La2CuO4 nanocoral perovskite catalytic electrode based on transient temperature field:

[0011] The precursor is subjected to direct current heat shock, and then cooled to room temperature in an air atmosphere to obtain a La2CuO4 electrocatalyst grown on a conductive substrate, that is, a method for constructing a nano-coral perovskite under a transient temperature field applied to high-value-added carbon reduction is completed.

[0012] The present application has the following advantages:

[0013] Firstly, the present application utilizes the phase change process under a transient temperature field and the transient vaporization process of a solution to form a large number of gas channels in the synthetic material, thereby constructing a coral-like microstructure at the nanoscale, which provides a large number of gas diffusion channels for carbon dioxide molecules and effectively increases the specific surface area of the synthetic perovskite material, thereby providing a larger electrochemical active area for the carbon dioxide catalytic reduction process.

[0014] Secondly, the present application utilizes the decomposition reaction under a transient temperature field to realize the direct preparation of a catalytic material on a substrate without additional adhesive components, which belongs to a self-supporting electrode system, effectively avoids the decline of catalytic stability caused by the catalyst falling off, and has an extremely short preparation period and excellent electrochemical stability.

[0015] Thirdly, the material synthesis method of the present application is simple and controllable, is not limited by the types of catalyst elements, is suitable for the synthesis of various oxide catalytic materials under a transient temperature field, has strong universality, and has a wide application prospect in the field of electrocatalytic carbon reduction.

[0016] Fourthly, the preparation process of the present application utilizes the characteristics of a high heating and cooling rate of a transient temperature field to promote the catalytic material to obtain a nano-coral structure with a high specific surface area, produce lattice distortion, increase the defect density, increase the number of carbon dioxide reduction catalytic sites, and thereby make it dominant in the competition with the hydrogen evolution reaction, effectively improving the carbon dioxide reduction efficiency. The catalytic electrode prepared by the method has a maximum faradic efficiency of 63.04% for methane at an electric current density of-10 mA / cm 2 , and a reaction potential of-1.24 V (vs. RHE). The problems of insufficient active sites, poor product selectivity, serious hydrogen evolution reaction, and the need to improve the faradic efficiency of the target product of the existing copper-based catalytic material are solved. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a scanning electron microscope image of the La2CuO4 electrocatalyst grown on the conductive substrate of Example 1.

[0018] Figure 2 It is an X-ray diffraction pattern, 1 is the original carbon cloth, and 2 is the La2CuO4 electrocatalyst grown on the conductive substrate of Example 1.

[0019] Figure 3The carbon reduction reaction Faraday efficiency of the La2CuO4 electrocatalyst grown on the conductive substrate in Example 1 at different current densities. DETAILED DESCRIPTION

[0020] Specific embodiment one: a method for constructing a nanocoral perovskite by using a transient temperature field for high-value carbon reduction, which is carried out according to the following steps:

[0021] I. Preparation of a precursor by a chemical bath immersion method:

[0022] ①Lanthanum oxide powder and copper oxide powder are dissolved in nitric acid to obtain solution I;

[0023] ②The solvent is added to solution I for dilution and stirring to obtain solution II;

[0024] ③The conductive substrate is immersed in solution II, and then taken out to obtain a precursor;

[0025] II. Preparation of a La2CuO4 nanocoral perovskite catalytic electrode based on a transient temperature field:

[0026] The precursor is subjected to direct current heat shock, and then cooled to room temperature in an air atmosphere to obtain a La2CuO4 electrocatalyst grown on the conductive substrate, i.e., the method for constructing a nanocoral perovskite by using a transient temperature field for high-value carbon reduction is completed.

[0027] The nanocoral perovskite electrocatalyst synthesized in this specific embodiment has a high defect density and a large number of catalytically active sites, and can be used for electrocatalytic carbon reduction reactions to achieve efficient selective reduction of methane.

[0028] The beneficial effects of this embodiment are:

[0029] I. Based on the phase transition process under the transient temperature field, the transient vaporization process of the solution is used to form a large number of gas channels inside the synthesized material, thereby constructing a coral-like microstructure at the nanoscale. This structure provides a large number of gas diffusion channels for carbon dioxide molecules, and effectively increases the specific surface area of the synthesized perovskite material, thereby providing a larger electrochemical active area for the catalytic reduction of carbon dioxide.

[0030] II. The decomposition reaction under the transient temperature field is used to realize the direct preparation of the catalytic material on the substrate without additional adhesive components, which belongs to a self-supporting electrode system. This effectively avoids the decline in catalytic stability caused by the catalyst falling off, and has an extremely short preparation period and excellent electrochemical stability.

[0031] Third, the material synthesis method of the embodiment is simple and controllable, is not limited by the type of catalyst element, is suitable for the synthesis of various oxide catalyst materials under a transient temperature field, has strong universality, and has a wide application prospect in the field of electrocatalytic carbon reduction.

[0032] Fourth, the preparation process of the embodiment utilizes the characteristics of the transient temperature field with extremely high heating and cooling rates, promotes the catalytic material to obtain a nano-coral structure with a high specific surface area, simultaneously produces lattice distortion, increases the defect density, increases the number of carbon dioxide reduction catalytic sites, and thus makes it dominant in the competition with the hydrogen evolution reaction, effectively improving the carbon dioxide reduction efficiency. The catalytic electrode prepared by the method has a maximum faradic efficiency of 63.04% for methane at a current density of-10 mA / cm 2 The reaction potential is-1.24 V (vs. RHE). The problems of existing copper-based catalytic materials, such as insufficient active sites, poor product selectivity, serious hydrogen evolution reaction, and target product faradic efficiency to be improved, are solved.

[0033] Specific embodiment two: The difference between this embodiment and specific embodiment one is that the molar ratio of lanthanum ions to copper ions in solution I in step one ① is 2:(0.7-1.3). The others are the same as specific embodiment one.

[0034] Specific embodiment three: The difference between this embodiment and one of specific embodiments one or two is that the mass percentage of nitric acid in step one ① is 2%-10%. The others are the same as specific embodiments one or two.

[0035] Specific embodiment four: The difference between this embodiment and one of specific embodiments one to three is that the volume ratio of the total mass of lanthanum oxide powder and copper oxide powder to the volume of nitric acid in step one ① is 1 g:(10-200) mL. The others are the same as specific embodiment three.

[0036] Specific embodiment five: The difference between this embodiment and one of specific embodiments one to four is that the solvent in step one ② is deionized water. The others are the same as specific embodiments one to four.

[0037] Specific embodiment six: The difference between this embodiment and one of specific embodiments one to five is that the concentration of lanthanum ions in solution II in step one ② is 1 mol / L-2.4 mol / L. The others are the same as specific embodiments one to five.

[0038] Specific embodiment seven: The difference between this embodiment and one of specific embodiments one to six is that the immersion in step one ③ is specifically to immerse the conductive substrate in solution II at room temperature and in an air atmosphere for 1 min-30 min. The others are the same as specific embodiments one to six.

[0039] Specific embodiment eight: the difference between this embodiment and one of the specific embodiments one to seven is that the conductive substrate in step one ③ is carbon cloth, carbon paper, copper foam or copper mesh. The others are the same as specific embodiments one to seven.

[0040] Specific embodiment nine: the difference between this embodiment and one of the specific embodiments one to eight is that the direct current thermal shock in step two is specifically direct current thermal shock for 5s-10s under the condition that the voltage is 10V-50V and the current is 10A-50A. The others are the same as specific embodiments one to eight.

[0041] Specific embodiment ten: the difference between this embodiment and one of the specific embodiments one to nine is that the peak temperature of the transient temperature field reached by the direct current thermal shock in step two is 500℃-1500℃. The others are the same as specific embodiments one to nine.

[0042] The beneficial effects of the present application are verified by the following examples:

[0043] Example one:

[0044] A method for constructing nanocoral perovskite by applying high value-added carbon reduction, which is carried out according to the following steps:

[0045] I. Preparation of precursor by chemical bath immersion method:

[0046] ①Dissolve lanthanum oxide powder and copper oxide powder in nitric acid to obtain solution I;

[0047] The molar ratio of lanthanum ions to copper ions in the solution I is 2:1; the mass percentage of the nitric acid is 5%; the total mass of the lanthanum oxide powder and the copper oxide powder to the volume of the nitric acid is 1g:100mL;

[0048] ②Add a solvent to solution I for dilution and stir uniformly to obtain solution II;

[0049] The solvent is deionized water; the concentration of lanthanum ions in the solution II is 2mol / L; the concentration of copper ions in the solution II is 1mol / L;

[0050] ③Under room temperature and air atmosphere, immerse the conductive substrate in solution II for 5min, then take it out to obtain the precursor;

[0051] The conductive substrate is 2×4cm 2 carbon cloth;

[0052] II. Preparation of La2CuO4 nanocoral perovskite catalytic electrode based on transient temperature field:

[0053] The precursor is subjected to direct current thermal shock for 10 s under the condition of 20 V voltage and 20 A current, and then cooled to room temperature in air atmosphere to obtain La2CuO4 electrocatalyst grown on the conductive substrate, i.e. the method for constructing nanocoral perovskite by transient temperature field for high-value carbon reduction application is completed;

[0054] The peak temperature of the direct current thermal shock reaches 1100 DEG C.

[0055] Figure 1 The scanning electron microscope image of the La2CuO4 electrocatalyst grown on the conductive substrate in Example 1; as shown in the figure, the surface of the prepared electrocatalytic electrode has a coral-like microstructure of 100 nm to 200 nm, which provides a large number of gas diffusion channels and a large amount of catalytic active area for electrocatalytic reaction.

[0056] Figure 2 The X-ray diffraction pattern, 1 is the original carbon cloth, and 2 is the La2CuO4 electrocatalyst grown on the conductive substrate in Example 1; as shown in the figure, the surface of the prepared catalytic electrode has only carbon phase and La2CuO4 perovskite phase.

[0057] Figure 3 The carbon reduction reaction Faraday efficiency of the La2CuO4 electrocatalyst grown on the conductive substrate in Example 1 under different current densities; under-10 mA / cm 2 The Faraday efficiency of the reaction to produce methane is up to 63.04%, and the reaction potential is-1.24 V (vs. RHE).

Claims

1. A method for constructing nano-coral perovskite by applying a transient temperature field to high-value-added carbon reduction, characterized in that It is carried out according to the following steps: I. Preparation of the precursor by chemical bath immersion method: ① Dissolve lanthanum oxide powder and copper oxide powder in nitric acid to obtain solution I; ② Add a solvent to solution I for dilution and stir to obtain solution II; ③ Dip the conductive substrate in solution II, then take it out to obtain the precursor; II. Preparation of La2CuO4 nanocoral perovskite catalytic electrode based on transient temperature field: Carry out direct current thermal shock on the precursor, then cool it to room temperature in air atmosphere to obtain La2CuO4 electrocatalyst grown on the conductive substrate, i.e. complete the method of constructing nanocoral perovskite based on transient temperature field for high value-added carbon reduction.

2. The method for constructing nano-coralline perovskite by applying transient temperature field to high-value-added carbon reduction according to claim 1, characterized in that The molar ratio of lanthanum ions to copper ions in solution I in step I ① is 2:(0.7-1.3).

3. The method for constructing nano-coralline perovskite by applying transient temperature field to high-value-added carbon reduction according to claim 1, characterized in that The mass percentage of nitric acid in step I ① is 2%-10%.

4. The method for constructing nano-coralline perovskite by applying transient temperature field to high-value-added carbon reduction according to claim 3, characterized in that The total mass of lanthanum oxide powder and copper oxide powder to the volume of nitric acid in step I ① is 1g:(10-200)mL.

5. The method for constructing nano-coralline perovskite by applying transient temperature field for high-value carbon reduction according to claim 1, characterized in that The solvent in step I ② is deionized water.

6. The method for constructing nano-coralline perovskite by applying transient temperature field for high-value carbon reduction according to claim 1, characterized in that The concentration of lanthanum ions in solution II in step I ② is 1mol / L-2.4mol / L.

7. The method according to claim 1, wherein the method is used for constructing nanocoral perovskite with high added value carbon reduction. The dipping in step I ③ is specifically dipping the conductive substrate in solution II at room temperature and in air atmosphere for 1min-30min.

8. The method for constructing nano-coralline perovskite by applying transient temperature field for high-value carbon reduction according to claim 1, characterized in that The conductive substrate in step I ③ is carbon cloth, carbon paper, copper foam or copper mesh.

9. The method for constructing nano-coralline perovskite by applying transient temperature field for high-value carbon reduction according to claim 1, characterized in that The direct current thermal shock in step II is specifically carrying out direct current thermal shock on the precursor under the conditions of voltage of 10V-50V and current of 10A-50A for 5s-10s.

10. The method for constructing nano-coralline perovskite by applying transient temperature field for high-value carbon reduction according to claim 1, characterized in that The peak temperature of the transient temperature field reached by the direct current thermal shock in step II is 500℃-1500℃.

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