Method for promoting in-situ dissolution of double-phase surface of perovskite and fluorite structure composite material

Abstract

The invention belongs to the technical field of fuel electrode preparation, and particularly relates to a method for promoting in-situ dissolution of a double-phase surface of a perovskite and fluorite structure composite material. Comprising the following steps: preparing composite fuel electrode material SCFM / GDC powder according to the chemical formula of the composite fuel electrode material Sr < 2 > Co < x > Fe < 1.6-x > Mo < 0.4 > O < 6-delta > / Gd < 0.1 > Ce < 0.9 > O < 2-delta >; preparing a GDCSSZGDC electrolyte framework; the method comprises the following steps: forming electrode slurry by SCFM / GDC, symmetrically coating two sides of an electrolyte skeleton with the electrode slurry, calcining to obtain a calcined product, carrying out acid treatment, and then carrying out reduction treatment, so that the CoFe bimetallic alloy nanoparticles on the SCFM and GDC dual-phase surfaces are dissolved in situ. According to the invention, an acid treatment method is adopted to promote in-situ dissolution of double-phase surface bimetallic alloy particles, so that the SOCs fuel electrode with large catalytic activity area, high electrochemical performance and low polarization impedance is obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fuel electrode preparation, and particularly relates to a method for promoting in-situ dissolution of a perovskite and fluorite structure composite material double-phase surface. BACKGROUND

[0002] Solid oxide cells (SOCs) are an economical, environmentally friendly and efficient electrochemical energy conversion device that realizes direct conversion between chemical fuels and electrical energy in two modes, fuel cell mode (FC mode) and electrolysis cell mode (EC mode). The fuel electrode is crucial for both the hydrogen oxidation reaction (HOR) in FC mode and the carbon dioxide reduction reaction (CO2RR) in EC mode. Traditional fuel electrodes mostly use perovskite and nickel / cubic fluorite structure oxides. Nickel has poor carbon deposition resistance, which can lead to a decrease in surface active sites and hinder electron transfer; while perovskite has multiple advantages over nickel / cubic fluorite structure oxides, such as rich and flexible component composition, high electrochemical activity and stability, which makes it the preferred material for fuel electrodes in both modes of SOCs. Among them, SrFe x Mo 1-x O 3-δ SrFe

[0003] The perovskite fuel electrode generally has a mismatch in the coefficient of thermal expansion (CTE) with commonly used fluorite structure electrolytes, and Sr and some electrolytes, such as scandia-stabilized zirconia (SSZ), will generate an impurity phase at high temperatures, thereby affecting the catalytic performance and stability. Composite electrodes and added barrier layers are usually used to solve the two problems of thermal mismatch and phase stability, such as gadolinia-stabilized ceria (GDC), which maintains a pure phase with SFM at high temperatures, and its CTE is between SFM and SSZ, so GDC is suitable for compounding with SFM, and as a functional layer, it can also alleviate thermal mismatch and prevent the formation of impurity phases. GDC has higher ionic conductivity, and compounding with SFM can further expand the electrochemically active region, but as a widely used electrolyte material, the catalytic activity of GDC is far behind that of the SFM phase.

[0004] Surface features greatly affect reactivity, so there are performance improvement strategies such as surface design or modification, including deposition, impregnation and out-diffusion. Impregnation and electrochemical deposition enhance the catalytic effect of fuel electrodes by adding external surface catalysts, however, the weak attachment between the substrate and the support makes it easy to aggregate at working temperature, resulting in unstable performance output. In-situ out-diffusion is a relatively more stable and effective strategy, which grows support particles from the substrate in an embedded state. The classic strategies to promote out-diffusion include A-site defects, B-site cation doping synergistic triggering, lattice strain control, etc. However, problems such as surface segregation of oxides, excessive lack of A-site instability, and B-site out-diffusion limitations still exist, and the surface out-diffusion of fluorite structure oxides is insufficient, which further limits the improvement of SOCs performance.

[0005] In order to improve the problem of insufficient activity of perovskite oxides and cubic fluorite oxides in the field of catalysis, Peng et al. (Yue Peng, Wenzhe Si, Jinming Luo, Wenkang Su, Huazhen Chang, Junhua Li, Jiming Hao, John Crittenden. Environmental Science & Technology, 50(12) (2016), 6442-6448) and Ma et al. (Qilei Yang, Jinyi Li, Dong Wang, Yue Peng, Yongliang Ma. Catalysis Today, 376 (2021), 205-210) have etched La 0.5 Sr 0.5 CoO3, LaFeO3, etc. perovskite by using dilute nitric acid, and obtained more active catalysts by increasing the specific surface area and reaction sites; Chi et al. (Xuzhuo Sun, Yunyun Xia, Bo Wang, Bo Li, Lushan Ma, Jing Chen, Bo Chi. Chemical Engineering Journal, 479, (2024), 147598) etched Pr 0.2 Sr 0.8 Co 0.2 Fe 0.8 O 3-δThe symmetrical electrodes were etched to obtain SOCs with higher performance. Hu et al. (Feng Hu, Kongfa Chen, Yihan Ling, Yonglong Huang, Sunce Zhao, Sijiao Wang, Liangqi Gui, Beibei He, Ling Zhao. Advanced Science, 11 (2024), 2306845) and Jiang et al. (Yunan Jiang, Lujuan Ye, Shaowei Zhang, Changrong Xia. Journal of Materials Chemistry A, 10, (2022), 9380-9383) improved the catalytic performance of ceria-based electrode materials by surface out-diffusion strategy. However, for composite materials, especially the construction of catalytic sites in the electrolyte phase, further modification and modification are still needed. SUMMARY

[0006] To solve the above problems, the application provides a method for promoting in-situ out-diffusion of double-phase surface of perovskite and fluorite structure composite material. The in-situ out-diffusion of double metal alloy particles on the double-phase surface is promoted to obtain SOCs fuel electrodes with large catalytic active area, high electrochemical performance and low polarization impedance.

[0007] The application solves the above technical problems by the following technical solutions.

[0008] The purpose of the application is to provide a method for promoting in-situ out-diffusion of double-phase surface of perovskite and fluorite structure composite material, comprising the following steps: S1, according to the composite fuel electrode material Sr2Co x Fe 1.6-x Mo 0.4 O 6-δ / Gd 0.1 Ce 0.9 O 2-δ , 0≤x≤0.4 chemical formula, to prepare the composite fuel electrode material SCFM / GDC powder.

[0009] S2, the gadolinium oxide doped ceria suspension is coated on both sides of the scandium oxide stabilized zirconia electrolyte sheet, and the first calcination obtains the GDC||SSZ||GDC electrolyte skeleton.

[0010] S3, the SCFM / GDC powder is prepared to form an electrode slurry, which is symmetrically coated on both sides of a GDC||SSZ||GDC electrolyte skeleton, and a second calcination is performed to obtain a calcination product, the calcination product is immersed in an acid for acid treatment, and then a reduction treatment is performed, so that the SCFM and GDC double-phase surface CoFe double-metal alloy nanoparticles are in-situ out-dissolved.

[0011] Further, the acid is acetic acid or nitric acid, the acid treatment temperature is 0-100°C, the acid treatment time is 0.5-1.5h, and the concentration of nitric acid is 0.1M.

[0012] Further, the mass fraction of SCFM / GDC in the electrode slurry is 60-80wt.%, the second calcination temperature is 1000-1100°C, and the time is 2-3h, and the second calcination is performed in an air atmosphere.

[0013] Further, the mass fraction of Sr2Co x Fe 1.6-x Mo 0.4 O 6-δ / Gd 0.1 Ce 0.9 O 2-δ in the composite fuel electrode material is 40-70wt.%. x Fe 1.6- x Mo 0.4 O 6-δ .

[0014] Further, the preparation method of the composite fuel electrode material Sr2Co x Fe 1.6-x Mo 0.4 O 6-δ / Gd 0.1 Ce 0.9 O 2-δ comprises the following steps: According to the composite fuel electrode material Sr2Co x Fe 1.6-x Mo 0.4 O 6-δ / Gd 0.1 Ce 0.9 O 2-δ , 0≤x≤0.4 is calculated and weighed, and soluble strontium salt, soluble cobalt salt, soluble iron salt, soluble molybdenum salt, soluble gadolinium salt and soluble cerium salt are mixed to form a metal salt, then citric acid and ethylenediaminetetraacetic acid are sequentially added to the metal salt, then water is added and the pH is adjusted to 6-8, stirring until the solution becomes a sol, drying and grinding, and then a third calcination is performed to prepare the composite fuel electrode material SCFM / GDC powder.

[0015] Further, the molar ratio of total metal ions, citric acid and ethylenediaminetetraacetic acid in the metal salt is 1:1-1.5:1.

[0016] Further, the temperature during stirring until the solution becomes a sol is 180-220 DEG C; the third calcination is divided into two stages, the first stage is at a temperature of 600-700 DEG C for 5-7 hours, and the second stage is at a temperature of 1050-1150 DEG C for 5-7 hours, and the third calcination is carried out in an air atmosphere.

[0017] Further, the preparation method of the gadolinium oxide doped cerium oxide suspension liquid comprises the following steps: The gadolinium oxide stabilized cerium oxide, ethyl cellulose and terpineol are mixed to obtain a GDC suspension liquid; the mass-volume ratio of the gadolinium oxide stabilized cerium oxide, ethyl cellulose and terpineol is 2g: 0.06-0.08g: 8-12mL.

[0018] Further, the temperature of the first calcination is 1200-1400 DEG C for 2-5 hours, and the first calcination is carried out in an air atmosphere.

[0019] Further, the reduction treatment is carried out at 750-850 DEG C in a hydrogen atmosphere for 1.5-2.5 hours.

[0020] Compared with the prior art, the present application has the following beneficial effects: The present application provides a method for promoting in-situ dissolution of a perovskite and fluorite structure composite material on a two-phase surface, preferentially etching Sr on a perovskite phase surface to generate an A-site defect layer, weakening surface Sr segregation; exposing B-site cations with higher catalytic activity, reducing the surface dissolution nucleation barrier; etching also generates nanoscale pits, significantly increasing surface roughness and active surface area; due to charge compensation, more oxygen vacancies are formed, which, in combination with surface A-site defects, promote the dissolution of CoFe alloy nanoparticles during the reduction process. Acid treatment also etches the GDC surface interface, increasing point defects and oxygen vacancies, greatly promoting the dissolution of Co and Fe on the GDC phase surface and diffusion between the two phases, forming a two-phase surface covered with dissolved particles with high catalytic activity. Through this surface treatment strategy, the surface micro-catalytic structure of the material is optimized, thereby significantly improving the electrocatalytic performance and durability of the material. It can not only solve the stability problems caused by surface Sr segregation and excessive lack of A-site in the in-situ dissolved SFM-based material in the fuel electrode, but also promote the in-situ dissolution of SCFM and GDC two-phase surface bimetallic alloy nanoparticles, which is of great significance and application value for SOCs fuel electrodes with large catalytic activity area, high electrochemical performance and low polarization impedance.

[0021] The acid treatment strategy and implementation method adopted by the present application include a raw material synthesis method, an acid treatment implementation method, a nanoparticle out-solution method, etc., and through the acid treatment method, the surface microstructure of the material is optimized, aiming to reduce production cost and improve production efficiency, and applied to a solid oxide battery composite fuel electrode, in both power generation and electrolysis modes of the battery, the catalytic activity of the electrode to H2 oxidation reaction and CO2 reduction reaction is improved, and higher power generation power density and electrolysis efficiency are exhibited. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 XRD patterns of SCFM / GDC-A, SCFM / GDC-A-R in Example 1 and SCFM / GDC, SCFM / GDC-R in Comparative Example 1.

[0023] Figure 2 Surface morphology SEM patterns of SCFM / GDC-A, SCFM / GDC-A-R in Example 1, SCFM / GDC-A30, SCFM / GDC-A30-R in Example 2 and SCFM / GDC, SCFM / GDC-R in Comparative Example 1. Figure 2 (a) is SCFM / GDC, (b) is SCFM / GDC-A, (c) is SCFM / GDC-A30, (d) is SCFM / GDC-R, (e) is SCFM / GDC-A-R, and (f) is SCFM / GDC-A30-R.

[0024] Figure 3 XPS patterns of SCFM / GDC-A, SCFM / GDC-A-R in Example 1 and SCFM / GDC, SCFM / GDC-R in Comparative Example 1. Figure 3 (a) is O 1s spectrum, (b) is Fe 2p spectrum, and (c) is Co 2p spectrum.

[0025] Figure 4 Polarization impedance spectrum of SCFM / GDC-A||GDC||SSZ||GDC||LSCF full cell and SCFM / GDC||GDC||SSZ||GDC||LSCF full cell of the present application in power generation mode at 800 DEG C. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0027] It should be noted that the professional terms used in the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the protection scope of the present application. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present application can be purchased from the market or prepared by the existing method.

[0028] For existing composite fuel electrode materials of SOCs, researchers focus more on the improvement of perovskite, especially the in-situ dissolution of surface nanoparticles of perovskite materials. The current mainstream dissolution promotion strategy is A-site defects, but too high A-site defects will produce impurity phases, greatly reducing the catalytic performance of the electrode, and negatively affecting the stable operation of solid oxide cells in two modes. The B-site cation doping and synergistic triggering strategy is limited to specific elements such as Cu, and is not universal. Therefore, SrFe x Mo 1-x O 3-δ The electrocatalytic activity of base perovskite fuel electrode under dual-mode working conditions and the stability in complex gas atmosphere still need to be improved. For ceria-based materials in composite electrodes, the electronic conductivity and catalytic ability are limited, and the research on improvement strategies such as surface modification, morphology improvement, and dissolution is less. The research on metal nanoparticles with higher catalytic activity and dissolution promotion strategies still needs to be developed.

[0029] Therefore, it is of great significance and application value to develop an acid treatment strategy and implementation method for promoting the in-situ dissolution of the dual-phase surface of perovskite and fluorite structure composite materials, which can solve the stability problems caused by surface Sr segregation, A-site excessive defects and other problems of SFM-based materials in fuel electrodes, and promote the in-situ dissolution of SCFM and GDC dual-phase surface bimetallic alloy nanoparticles, which are used for SOCs fuel electrodes with large catalytic activity area, high electrochemical performance and low polarization impedance.

[0030] Based on this, the present application provides a method for promoting the in-situ dissolution of the dual-phase surface of perovskite and fluorite structure composite materials, comprising the following steps: S1, according to the composite fuel electrode material Sr2Co x Fe 1.6-x Mo 0.4 O 6-δ / Gd 0.1 Ce0.9 O 2-δ , 0≤x≤0.4 Chemical formula, to prepare composite fuel electrode material SCFM / GDC powder.

[0031] S2, the gadolinium oxide doped cerium oxide suspension is coated on both sides of the scandium oxide stabilized zirconia electrolyte sheet, and the first calcination obtains the GDC||SSZ||GDC electrolyte skeleton.

[0032] S3, the SCFM / GDC powder is dispersed in a solvent to form an electrode slurry, the electrode slurry is symmetrically coated on both sides of the GDC||SSZ||GDC electrolyte skeleton, and the second calcination obtains a calcination product, the calcination product is immersed in an acid for acid treatment to obtain an acid-treated SCFM / GDC-A, and the SCFM / GDC-A is subjected to reduction treatment, so that the SCFM and GDC double-phase surface CoFe bimetallic alloy nanoparticles are in-situ out-dissolved, to obtain a bimetallic out-dissolved promoted SCFM / GDC-A-R, which is a double-phase surface in-situ out-dissolved perovskite and fluorite structure composite material.

[0033] In the present application, the surface of the SCFM / GDC nanocomposite material is selectively etched by adopting an acid treatment strategy to reconstruct a multi-level catalytic structure. First, the surface acid treatment technology has a more stable bulk crystal structure, which selectively etches the surface metal ions and creates more oxygen vacancies, which is beneficial to surface nucleation and element migration, forming more nanoparticles; second, the nanoscale pits etched on the surface increase the surface active area and provide more reaction sites; third, the acid treatment technology greatly promotes the out-dissolution of the GDC surface nanometer alloy particles, improving its catalytic performance as an ion conductor; finally, the acid treatment technology is simple and efficient, and has good application prospects. Therefore, the acid treatment technology reconstructs the surface of the composite material, promotes the in-situ out-dissolution of the double-phase surface, obtains a high catalytic activity multi-level morphology structure, and has higher phase stability and electrochemical performance. Through this surface treatment strategy, the surface micro-catalytic structure of the material is optimized, thereby significantly improving the electrocatalytic performance and durability of the material.

[0034] The acid treatment strategy and implementation method adopted in the present application include a synthesis method of raw materials, an implementation method of acid treatment, a nanoparticle out-dissolution method, etc. By means of acid treatment, the surface microstructure of the material is optimized, aiming to reduce production cost and improve production efficiency, and is applied to a solid oxide battery composite fuel electrode. In both power generation and electrolysis modes of the battery, the catalytic activity of the battery to H2 oxidation reaction and CO2 reduction reaction is improved, and the battery exhibits higher power generation power density (>1 W·cm -2 , 800℃) and electrolysis efficiency (>1.5 A·cm -2 , 1.6V-800℃).

[0035] In some embodiments, the acid is acetic acid or nitric acid, the acid treatment temperature is 0°C to 100°C, the acid treatment time is 0.5h to 1.5h, the acetic acid is pure acetic acid, and the concentration of nitric acid is 0.1M. As a preferred embodiment of the present invention, pure acetic acid is used for treatment at 100°C for 0.5h and 1h. After the acid treatment is completed, the mixture is rinsed with deionized water and dried. The electrode is scraped to obtain the acid-treated SCFM / GDC-A powder.

[0036] In some embodiments, the mass fraction of SCFM / GDC in the electrode slurry is 60wt.% to 80wt.%, the second calcination temperature is 1000℃ to 1100℃, the time is 2h to 3h, and the second calcination is carried out in an air atmosphere.

[0037] In some embodiments, the composite fuel electrode material Sr2Co x Fe 1.6-x Mo 0.4 O 6-δ / Gd 0.1 Ce 0.9 O 2-δ Sr2Co x Fe 1.6-x Mo 0.4 O 6-δ The mass fraction is 40 wt.%–70 wt.%. Composite fuel electrode material Sr2Co x Fe 1.6- x Mo 0.4 O 6-δ / Gd 0.1 Ce 0.9 O 2-δ The preparation method includes the following steps:

[0038] Based on the composite fuel electrode material Sr2Co x Fe 1.6-x Mo 0.4 O 6-δ / Gd 0.1 Ce 0.9 O 2-δ Calculate and weigh the chemical formulas of soluble strontium salt, soluble cobalt salt, soluble iron salt, soluble molybdenum salt, soluble gadolinium salt, and soluble cerium salt, and mix them to form a metal salt. Then, add citric acid and ethylenediaminetetraacetic acid to the metal salt in sequence, then add water and adjust the pH to 6-8. Stir until the solution becomes a sol, dry and grind, and then calcine for the third time to prepare the composite fuel electrode material SCFM / GDC powder.

[0039] As a preferred scheme of the present application, the soluble strontium salt is Sr(NO3)2, the soluble cobalt salt is Co(NO3)2·6H2O, the soluble iron salt is Fe(NO3)3·9H2O, the soluble molybdenum salt is (NH4)6Mo7O 24 ·4H2O, the soluble gadolinium salt is Gd(NO3)2·6H2O, and the soluble cerium salt is Ce(NO3)2·6H2O.

[0040] In some embodiments, the molar ratio of total metal ions, citric acid and ethylenediaminetetraacetic acid in the metal salt is 1:1-1.5:1. The purpose of water is to dissolve the metal salt, citric acid and ethylenediaminetetraacetic acid to form a mixed solution, therefore, the amount of water is not specifically limited, and can be adjusted according to the actual situation. Ammonia is used to adjust the pH to about 6-8, and stirring is performed on a heating table at 180-220°C until the solution becomes a sol, to obtain a sol. The sol is dried at 170-190°C for 4-6h, and then ball-milled for 1.5-3h to obtain a powder precursor. As a preferred scheme of the present application, the molar ratio of total metal ions, citric acid and ethylenediaminetetraacetic acid in the metal salt is 1:1.5:1, ammonia is used to adjust the pH to about 7, and stirring is performed on a heating table at 180°C until the solution becomes a sol, to obtain a sol which is dried at 180°C for 5h, and then ball-milled for 2h to obtain a powder precursor.

[0041] In some embodiments, the temperature during stirring until the solution becomes a sol is 180-220°C; the third calcination is divided into two stages, the first stage is at a temperature of 600-700°C for 5-7h, and the second stage is at a temperature of 1050-1150°C for 5-7h, and the third calcination is performed in an air atmosphere. As a preferred scheme of the present application, after the third calcination is completed, the obtained crude product is ground for 2h to obtain the one-pot synthesized composite fuel electrode material Sr2Co x Fe 1.6-x Mo 0.4 O 6-δ / Gd 0.1 Ce 0.9 O 2-δ , which is SCFM / GDC powder.

[0042] In some embodiments, the preparation method of the gadolinium oxide doped cerium oxide suspension includes the following steps: The gadolinium oxide stabilized cerium oxide, ethyl cellulose and terpineol are mixed to obtain a GDC suspension; wherein the mass-volume ratio of the gadolinium oxide stabilized cerium oxide, ethyl cellulose and terpineol is 2g: 0.06g-0.08g: 8mL-12mL. As a preferred scheme of the present application, the solvent is terpineol and turpentine oil mixed in a mass ratio of 5:95 and stirred uniformly, the mass fraction of SCFM / GDC in the electrode slurry is 75%, the electrode slurry is symmetrically coated at the center position of the GDC||SSZ||GDC electrolyte skeleton by using the screen printing method, and then calcination treatment is performed, the temperature is 1000°C, and the time is 2h. As a preferred scheme of the present application, the GDC suspension is ball milled for 24h, then spin coated on one side of the SSZ electrolyte sheet, dried and calcined at 1300°C for 3h, and then the above steps are repeated on the other side to obtain the GDC||SSZ||GDC electrolyte skeleton.

[0043] In some embodiments, a perovskite and fluorite structure composite material SCFM / GDC-A-R is obtained in situ after the reduction treatment, and the reduction treatment condition is: reduction at 750°C-850°C in a hydrogen atmosphere for 1.5h-2.5h. As a preferred scheme of the present application, reduction is performed at 800°C in a hydrogen atmosphere for 2h.

[0044] The following is further illustrated by specific examples.

[0045] Example 1 A method for promoting in-situ dissolution of a perovskite and fluorite structure composite material on a two-phase surface, comprising the following steps: S1, preparation of a composite fuel electrode material: According to the double perovskite type solid oxide fuel electrode material Sr2Co 0.4 Fe 1.2 Mo 0.4 O 6-δ , the raw materials of Sr(NO3)2, Co(NO3)2·6H2O, Fe(NO3)3·9H2O and (NH4)6Mo7O 24 ·4H2O are calculated and weighed, then the raw materials of Gd(NO3)2·6H2O and Ce(NO3)2·6H2O are calculated and weighed according to the stoichiometric ratio of the gadolinium oxide stabilized cerium oxide Gd 0.1 Ce 0.9 O 2-δ , wherein the raw materials of Sr2Co 0.4 Fe 12 Mo 0.4 O 6-δ and Gd 0.1 Ce 0.9 O 2-δThe mass ratio of the two is 6:4. All the nitrate raw materials are placed in a clean beaker. Then, the molar ratio of total metal ions: citric acid (CA): ethylenediaminetetraacetic acid (EDTA) is 1:1.5:1. The CA and EDTA are weighed and added to the clean beaker. 400 mL of deionized water is added for stirring, and ammonia water is added to adjust the pH to about 7. The stirring is continued on a heating table at 180°C until a sol state is obtained, and a sol is obtained. The sol is dried in an oven at a temperature of 180°C for 5h, and a gel is obtained. The gel is coarsely ground and placed in a clean dry ball mill tank. After ball milling for 2h, a fine mixed raw material is obtained. The fine powder is calcined in an air environment at 650°C for 6h, and then the temperature is increased to 1100°C for calcination for 6h, and a coarse product of a composite fuel electrode material is obtained. The composite fuel electrode material Sr2Co 0.4 Fe 1.2 Mo 0.4 O 6-δ / Gd 0.1 Ce 0.9 O 2-δ The fine powder is SCFM / GDC fine powder.

[0046] S2, Preparation of GDC||SSZ||GDC electrolyte skeleton: 2g of GDC powder, 0.08g of ethyl cellulose, and 12mL of pine oil alcohol solution are mixed, and ball milling is performed for 24h to obtain a GDC suspension. An SSZ electrolyte sheet is placed on a spin coater rotating platform, and an appropriate amount of GDC suspension is coated on the surface. A two-stage spin coating program is started, with the first stage rotating at 500r / min and the second stage rotating at 1500r / min, both for 30s. After spin coating, the electrolyte sheet is transferred to a 70°C oven for drying, and then calcined at 1300°C for 3h. The same step is repeated on the other side to obtain a GDC||SSZ||GDC electrolyte skeleton structure.

[0047] S3, Acid treatment and in-situ out-dissolution method of composite electrode material: The terpineol and turpentine oil are mixed in a mass ratio of 5:95 and stirred uniformly to obtain an organic solvent, and then the SCFM / GDC powder is mixed with the organic solvent to obtain an electrode slurry, wherein the mass fraction of the SCFM / GDC powder is 75 wt.%. The electrode slurry is symmetrically applied to the center positions on both sides of the electrolyte skeleton by using a screen printing method, and is calcined at 1000°C for 2h in an air atmosphere. Subsequently, the electrode slurry is immersed in a crucible containing a proper amount of pure acetic acid placed on a 100°C heating table for 1h, so that the SCFM and GDC bi-phase surface CoFe bimetallic alloy nanoparticles are in-situ out-dissolved. After being taken out, the electrode is cleaned with a flowing deionized water and dried, and the electrode is scraped to obtain the SCFM / GDC-A powder after acid treatment. The SCFM / GDC-A powder is reduced in a H2 atmosphere at 800°C for 2h to obtain the SCFM / GDC-A-R powder, which is a perovskite and fluorite structure composite material with in-situ out-dissolved bi-phase surface.

[0048] Example 2 A method for promoting in-situ out-dissolution of a perovskite and fluorite structure composite material surface, comprising the following steps: S1, preparation of a composite fuel electrode material: According to the stoichiometric ratio of the double perovskite type solid oxide fuel electrode material Sr2Co 0.4 Fe 1.2 Mo 0.4 O 6-δ , the raw materials of Sr(NO3)2, Co(NO3)2·6H2O, Fe(NO3)3·9H2O and (NH4)6Mo7O 24 ·4H2O are calculated and weighed, and then the raw materials of Gd(NO3)2·6H2O and Ce(NO3)2·6H2O are calculated and weighed according to the stoichiometric ratio of gadolinium oxide stabilized cerium oxide Gd 0.1 Ce 0.9 O 2-δ , wherein the stoichiometric ratio of Sr2Co x Fe 1.6-x Mo 0.4 O 6-δ and Gd 0.1 Ce 0.9 O 2-δThe mass ratio of the two is 6:4. All the nitrate raw materials are placed in a clean beaker. Then, the molar ratio of total metal ions: citric acid (CA): ethylenediaminetetraacetic acid (EDTA) is 1:1.5:1. The CA and EDTA are weighed and added to the clean beaker. 400 mL of deionized water is added for stirring. Ammonia water is added to adjust the pH to about 7. The stirring is continued on a heating table at 180°C until a sol state is obtained, and a sol is obtained. The sol is dried in an oven at a temperature of 180°C for 5h to obtain a gel. The gel is coarsely ground and placed in a clean dry ball mill tank. After ball milling for 2h, fine raw materials are obtained. The fine powder is calcined at 650°C for 6h in an air environment, and then the temperature is increased to 1100°C for 6h calcination, to obtain a crude product of a composite fuel electrode material. The composite fuel electrode material Sr2Co 0.4 Fe 1.2 Mo 0.4 O 6-δ / Gd 0.1 Ce 0.9 O 2-δ The fine powder is SCFM / GDC fine powder.

[0049] S2, Preparation of GDC||SSZ||GDC electrolyte skeleton: 2g of GDC powder, 0.08g of ethyl cellulose, and 12mL of pine oil alcohol solution are mixed, and ball milling is performed for 24h to obtain a GDC suspension. An SSZ electrolyte sheet is placed on a spin coater rotating platform. An appropriate amount of GDC suspension is coated on the surface. A two-stage spin coating program is started, with the first stage speed being 500r / min and the second stage speed being 1500r / min, both lasting for 30s. After spin coating, the electrolyte sheet is transferred to a 70°C oven for drying, and then high-temperature calcination at 1300°C for 3h. The same step is repeated on the other side to obtain a GDC||SSZ||GDC electrolyte skeleton structure.

[0050] S3, Acid treatment and in-situ out-dissolution method of composite electrode material: The terpineol and turpentine are mixed in a mass ratio of 5:95 and stirred uniformly to obtain an organic solvent, and then the SCFM / GDC powder is mixed with the organic solvent to obtain an electrode slurry, wherein the mass fraction of the SCFM / GDC powder is 75 wt.%. The electrode slurry is symmetrically applied to the center positions on both sides of the electrolyte skeleton by using a screen printing method, and is calcined at 1000°C for 2h in an air atmosphere. Subsequently, the electrode slurry is immersed in a crucible containing a proper amount of pure acetic acid placed on a 100°C heating table for 30min, so that the SCFM and GDC bi-phase surface CoFe bimetallic alloy nanoparticles are in-situ out-dissolved. After being taken out, the electrode is cleaned with a flowing deionized water and dried, and the electrode is scraped to obtain the SCFM / GDC-A30 powder after acid treatment. The SCFM / GDC-A30 powder is reduced in a H2 atmosphere at 800°C for 2h to obtain the SCFM / GDC-A30-R powder, which is a perovskite and fluorite structure composite material with in-situ out-dissolved bi-phase surface.

[0051] Comparative Example 1 A method for in-situ out-dissolving a perovskite and fluorite structure composite material surface, comprising the following steps: S1, preparation of a composite fuel electrode material: According to the stoichiometric ratio of the double perovskite type solid oxide fuel electrode material Sr2Co 0.4 Fe 1.2 Mo 0.4 O 6-δ , the raw materials of Sr(NO3)2, Co(NO3)2·6H2O, Fe(NO3)3·9H2O and (NH4)6Mo7O 24 ·4H2O are calculated and weighed. 0.1 Ce 0.9 O 2-δ , the raw materials of Gd(NO3)2·6H2O and Ce(NO3)2·6H2O are calculated and weighed, wherein the stoichiometric ratio of Sr2Co 0.4 Fe 1.2 Mo 0.4 O 6-δ and Gd 0.1 Ce 0.9 O 2-δThe mass ratio of the two is 6:4. All the nitrate raw materials are placed in a clean beaker. Then, the molar ratio of total metal ions: citric acid (CA): ethylenediaminetetraacetic acid (EDTA) is 1:1.5:1. CA and EDTA are weighed and added to the clean beaker. Deionized water is added for stirring, and ammonia water is added to adjust the pH to about 7. The stirring is continued on a heating table at 180°C until a sol state is reached, and a sol is obtained. The sol is dried in an oven at a temperature of 180°C for 5h to obtain a gel. The gel is coarsely ground and placed in a clean dry ball mill tank. After ball milling for 2h, fine mixed raw materials are obtained. The fine powder is calcined in an air environment at 650°C for 6h, and then the temperature is increased to 1100°C for calcination for 6h to obtain a coarse product of the composite fuel electrode material. The coarse product is ground again for 2h to obtain the composite fuel electrode material Sr2Co 0.4 Fe 1.2 Mo 0.4 O 6-δ / Gd 0.1 Ce 0.9 O 2-δ The fine powder is SCFM / GDC fine powder.

[0052] S2, Preparation of GDC||SSZ||GDC electrolyte framework: 2g of GDC powder, 0.08g of ethyl cellulose, and 12mL of pine oil alcohol solution are mixed, and the mixture is ball milled for 24h to obtain a GDC suspension. An SSZ electrolyte sheet is placed on the rotating platform of a spin coater, and an appropriate amount of GDC suspension is coated on the surface of the electrolyte sheet. A two-stage spin coating program is started, with the first stage at a speed of 500r / min and the second stage at a speed of 1500r / min, both lasting for 30s. After spin coating, the electrolyte sheet is transferred to a 70°C oven for drying, and then calcined at a high temperature of 1300°C for 3h. The same procedure is repeated on the other side to obtain a GDC||SSZ||GDC electrolyte framework structure.

[0053] S3, Acid treatment and in-situ out-dissolution method of composite electrode material: The pine oil and turpentine are mixed in a mass ratio of 5:95 and stirred uniformly to obtain an organic solvent. Then, the SCFM / GDC powder is mixed with the organic solvent to obtain an electrode slurry, wherein the mass fraction of the SCFM / GDC powder is 75%. The electrode slurry is symmetrically applied to the center positions on both sides of the electrolyte framework using a screen printing method. The electrode slurry is calcined at 1000°C in an air atmosphere for 2h, and the electrode powder is scraped off. The electrode powder is reduced in a H2 atmosphere at 800°C for 2h to obtain SCFM / GDC-R powder with surface in-situ out-dissolved CoFe alloy nanoparticles.

[0054] The SCFM / GDC-A-R powder prepared in Example 1 and the SCFM / GDC-R powder prepared in Comparative Example 1 are subjected to structure and performance testing, and the results are as follows: Figure 1 XRD patterns of SCFM / GDC-A, SCFM / GDC-A-R in Example 1 and SCFM / GDC, SCFM / GDC-R in Comparative Example 1 of the present application. As shown in Figure 1 there is no impurity phase before and after acid treatment, and the reduced sample has obvious Co-Fe alloy diffraction peak intensity, representing the dissolution of Co-Fe nano-alloy particles on the surface.

[0055] Figure 2 SEM images of the surface morphology of SCFM / GDC-A, SCFM / GDC-A-R in Example 1, SCFM / GDC-A30, SCFM / GDC-A30-R in Example 2 and SCFM / GDC, SCFM / GDC-R in Comparative Example 1 of the present application. Figure 2 (a) is SCFM / GDC, (b) is SCFM / GDC-A, (c) is SCFM / GDC-A30, (d) is SCFM / GDC-R, (e) is SCFM / GDC-A-R, and (f) is SCFM / GDC-A30-R. As shown in Figure 2 After acid treatment, nano-scale pits appear on the surface. After reduction, in SCFM / GDC-R, the full-surface metal particles are dissolved into SCFM phase, while the GDC phase only appears alloy particles near the interface with SCFM. In SCFM / GDC-A30-R, alloy particles are also dissolved on the surface of the GDC phase away from the interface. In SCFM / GDC-A-R, the surface of the GDC phase appears higher density and more uniform alloy particle dissolution.

[0056] Figure 3 XPS patterns of SCFM / GDC-A, SCFM / GDC-A-R in Example 1 and SCFM / GDC, SCFM / GDC-R in Comparative Example 1 of the present application. Figure 3 (a) is O 1s spectrum, (b) is Fe 2p spectrum, and (c) is Co 2p spectrum. As shown in Figure 3 After acid treatment, SCFM / GDC-A has more oxygen vacancies; compared with SCFM / GDC-R, the proportion of 0 valence state of Co and Fe elements in SCFM / GDC-A-R is higher, representing higher content of Co-Fe alloy dissolved on the surface.

[0057] The SCFM / GDC-A-R powder prepared in Example 1 is used for a full cell, including the following steps: using a screen printing method to apply SCFM / GDC composite fuel electrode slurry to the center position on one side of the electrolyte framework, drying in an 80°C oven, and then applying La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3-δ (LSCF) air electrode slurry was applied to the center of the other side, and after drying, the whole was calcined at 1000°C in air atmosphere for 2h. The fuel electrode was placed upward on a 100°C heating stage, and acetic acid was continuously dropped for 1h. After cleaning with flowing deionized water and drying, silver slurry was applied to the electrode attachment of both sides of the electrolyte skeleton, and silver wires were used for lead-out. After drying at 180°C, the SCFM / GDC-A||GDC||SSZ||GDC||LSCF full cell was obtained for electrochemical performance test. Before formal test, the fuel electrode of the cell needs to be reduced in H2 atmosphere for 2h.

[0058] The SCFM / GDC-R powder prepared in Comparative Example 1 was used for a full cell, including the following steps: the SCFM / GDC composite fuel electrode slurry was applied to the center of one side of the electrolyte skeleton by screen printing, and after drying in an 80°C oven, the LSCF air electrode slurry prepared in the same way was applied to the center of the other side. After drying, the whole was calcined at 1000°C in air atmosphere for 2h. Silver slurry was applied to the electrode attachment of both sides of the electrolyte skeleton, and silver wires were used for lead-out. After drying at 180°C, the SCFM / GDC||GDC||SSZ||GDC||LSCF full cell was obtained for electrochemical performance test. Before formal test, the fuel electrode of the cell needs to be reduced in H2 atmosphere for 2h.

[0059] Figure 4 The SCFM / GDC-A||GDC||SSZ||GDC||LSCF full cell and the SCFM / GDC||GDC||SSZ||GDC||LSCF full cell of the present application were polarized impedance spectrograms at 800°C in power generation mode. As shown in FIG. 6, acid treatment improved the electrochemical performance of the composite fuel electrode material. Figure 4

[0060] The Sr and Ce elements of the SCFM / GDC and SCFM / GDC-A powders in Example 1 were detected by inductively coupled plasma emission spectrometer ICP-OES, and the results are shown in Table 1. The ICP element content analysis results show that after acid treatment, the Sr element at the A site of the perovskite phase is the main etching object, and its proportion in all elements of the perovskite phase is reduced by 1.79%; Ce in the GDC phase is the main etching object, and the proportion of Ce / (Ce+Gd) is reduced by 0.63%.

[0061] Table 1 Sr and Ce element content of SCFM / GDC and SCFM / GDC-A powders in Example 1 ​It is to be understood that every range of values disclosed herein is to be understood to encompass any and every sub-range of values within the range. Although the preferred embodiments of the invention have been described above, it will be appreciated that those skilled in the art, on consideration of this disclosure, will be able to devise additional embodiments that, although not explicitly described or shown herein, nonetheless fall within the scope of the present invention. Accordingly, the appended claims are intended to include within their scope all such alternatives, modifications and variations as fall within the scope of the present invention. Various features and aspects of the present invention will become apparent from the following examples, which are intended only to exemplify the invention. It should be understood, of course, that in the various examples of the present invention, the specific phrasing of the claims will depend on the exact nature of the claims sought.

[0062] Obviously, numerous modifications and variations of the present application are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims and their equivalents, the present application can be practiced otherwise than as specifically described herein.

Claims

1. A method of promoting in-situ exsolution of a double phase surface of a perovskite and fluorite structure composite material, characterized in that, The method comprises the following steps: According to the composite fuel electrode material Sr2Co x Fe 1.6-x Mo 0.4 O 6-δ / Gd 0.1 Ce 0.9 O 2-δ , 0≤x≤0.4 chemical formula, a composite fuel electrode material SCFM / GDC powder is prepared; The Gd-doped CeO2 suspension is coated on both sides of the Sc2O3-stabilized ZrO2 electrolyte sheet, and a first calcination is performed to obtain a GDC||SSZ||GDC electrolyte skeleton; The SCFM / GDC powder is prepared into an electrode slurry, which is symmetrically coated on both sides of the GDC||SSZ||GDC electrolyte skeleton, and a second calcination is performed to obtain a calcination product, which is immersed in an acid for acid treatment and then subjected to a reduction treatment, so that the SCFM and GDC bi-phase surface CoFe bimetallic alloy nanoparticles are in-situ precipitated.

2. The method of claim 1, wherein the method is characterized by, The acid is acetic acid or nitric acid, the acid treatment temperature is 0-100 DEG C, the acid treatment time is 0.5-1.5 h, and the concentration of the nitric acid is 0.1 M.

3. The method of facilitating in situ out-diffusion of a perovskite and fluorite structure composite bi-phase surface of claim 1, wherein, The mass fraction of the SCFM / GDC in the electrode slurry is 60-80 wt.%, the second calcination temperature is 1000-1100 DEG C, and the second calcination time is 2-3 h.

4. The method of facilitating in situ out-diffusion of a perovskite and fluorite structure composite bi-phase surface of claim 1, wherein, Composite fuel electrode material Sr2Co x Fe 1.6-x Mo 0.4 O 6-δ / Gd 0.1 Ce 0.9 O 2-δ middle Sr2Co x Fe 1.6-x Mo 0.4 O 6-δ 40wt.%~70wt.%.

5. The method of facilitating in situ out-diffusion of a perovskite and fluorite structure composite bi-phase surface of claim 1, wherein, Composite fuel electrode material Sr2Co x Fe 1.6-x Mo 0.4 O 6-δ / Gd 0.1 Ce 0.9 O 2-δ A method of producing a composite fuel electrode material Sr2Co According to the composite fuel electrode material Sr2Co x Fe 1.6-x Mo 0.4 O 6-δ / Gd 0.1 Ce 0.9 O 2-δ , 0≤x≤0.4 chemical formula calculation and weighing, soluble strontium salt, soluble cobalt salt, soluble iron salt, soluble molybdenum salt, soluble gadolinium salt and soluble cerium salt, mixed to form metal salt, then citric acid and ethylenediaminetetraacetic acid are added to the metal salt in turn, then water is added and the pH is adjusted to 6-8, stirring until the solution becomes sol, dried and ground, and then third calcination is carried out to prepare the composite fuel electrode material SCFM / GDC powder.

6. The method of facilitating in situ out-diffusion of a perovskite and fluorite structure composite bi-phase surface of claim 5, wherein, The molar ratio of the total metal ions, citric acid and ethylenediaminetetraacetic acid in the metal salt is 1:1-1.5:

1.

7. The method of facilitating in situ out-diffusion of a perovskite and fluorite structure composite bi-phase surface of claim 5, wherein, The temperature during the stirring until the solution becomes a sol is 180-220 DEG C, the third calcination is divided into two stages, the first stage temperature is 600-700 DEG C, the first stage time is 5-7 h, the second stage temperature is 1050-1150 DEG C, and the second stage time is 5-7 h.

8. The method of facilitating in situ out-diffusion of a perovskite and fluorite structure composite bi-phase surface of claim 1, wherein, The method for preparing the Gd-doped CeO2 suspension comprises the following steps: The Gd-doped CeO2 suspension is prepared by mixing Gd-doped CeO2, ethyl cellulose and terpineol, wherein the mass-volume ratio of the Gd-doped CeO2, ethyl cellulose and terpineol is 2g:0.06-0.08g:8-12mL.

9. The method of facilitating in situ out-diffusion of a perovskite and fluorite structure composite bi-phase surface of claim 1, wherein, The first calcination temperature is 1200-1400 DEG C, and the first calcination time is 2-5 h.

10. The method of facilitating in situ out-diffusion of a perovskite and fluorite structure composite bi-phase surface of claim 1, wherein, The reduction treatment is performed at 750-850 DEG C in a hydrogen atmosphere for 1.5-2.5 h.

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