A new type of double perovskite catalytic material, electrode material and solid oxide cell

Abstract

The application belongs to the technical field of electrocatalysis, and particularly relates to a novel double-perovskite catalytic material, an electrode material and a solid oxide cell. 1.5‑x Mo 0.5 O 6‑δ (SFM) are doped with platinum at the beta position, to obtain a novel double-perovskite catalytic material Sr2Fe 1.5‑x Mo 0.5 Pt x O6, wherein x is less than or equal to 0.01. The novel double-perovskite catalytic material provided by the application can promote the progress of the methane-assisted water electrolysis reaction by doping with an appropriate amount of platinum, reduce the ohmic resistance and polarization resistance of the electrode, and also reduce the required overvoltage of the reaction, thereby improving the power density of the cell.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalysis technology, and specifically relates to a novel double perovskite catalytic material, electrode material, and solid oxide battery. Background Technology

[0002] Traditional SOEC is the reverse process of solid oxide fuel cell (SOFC). Taking high-temperature water electrolysis as an example, high-temperature water vapor gains electrons at a conventional Ni-based cathode and is reduced to hydrogen and oxygen ions (O2). 2- ), O 2- Driven by an external voltage, oxygen overcomes a certain oxygen partial pressure gradient and passes through the electrolyte, from the cathode to the anode, where it releases electrons to generate oxygen. SOEC typically uses hydrogen as a carrier gas to keep the cathode in a reducing atmosphere, while the anode, as the oxygen-generating side, is placed in the air. Therefore, traditional SOEC requires overcoming a very high potential difference to achieve oxygen generation. 2- The reverse migration from cathode to anode. CH4-assisted SOEC has great potential in reducing the operating cost of water electrolysis for hydrogen production, improving the efficiency of water electrolysis for hydrogen production, and promoting the commercialization of high-temperature electrolysis technology. Based on the type of methane reaction on the anode side, methane-assisted SOEC can be divided into two main categories: partial methane oxidation (POM)-assisted SOEC and deep methane oxidation-assisted SOEC. The anode-side products of both are high-value-added products—syngas and CO2+H2O, respectively. Therefore, the POM-assisted SOEC mode has greater potential for commercial application. Simultaneously, it is essential to develop high-performance, high-stability electrode materials that promote the methane-assisted SOEC mode.

[0003] Sr2Fe, a double perovskite material as a mixed ion-electron conductor 1.5 Mo 0.5 O6 (SFM) has attracted much attention due to its excellent resistance to carbon deposition and sulfur poisoning, as well as its high thermochemical stability and ionic conductivity. However, due to the presence of Fe in SFM materials... 2+ / Fe 3+ Due to the variable valence of Sr2FeMoO, SFM materials exhibit high electrical conductivity and good catalytic activity. Furthermore, when the Fe / Mo ratio is 1:1, Sr2FeMoO2... 6-δ It can only be synthesized in a reducing atmosphere to produce the pure phase; in an air atmosphere, it decomposes rapidly and produces impurities such as SrMoO4, thus exhibiting poor redox stability. When the Fe / Mo ratio is 3:1, Sr2Fe... 1.5 Mo 0.5 O 6-δ The material maintains a stable double perovskite structure in both air and reducing atmospheres, and has high electronic conductivity and electrochemical performance, but its ionic conductivity is low and its coefficient of thermal expansion is high. Summary of the Invention

[0004] To overcome the high potential difference in SOEC mode and improve the efficiency of hydrogen production through water electrolysis, this invention aims to provide a novel double perovskite catalyst material, electrode material, and solid oxide battery. The specific technical solution is as follows: The first aspect of this invention provides a novel double perovskite catalytic material, wherein platinum is doped at the β-site of the catalytic material SFM to obtain the novel double perovskite catalytic material Sr2Fe. 1.5-x Mo 0.5 Pt x O6, where x≤0.01.

[0005] Furthermore, the novel dual perovskite catalytic material Sr2Fe of this invention... 1.5-x Mo 0.5 Pt x The preparation process for O6 is not limited; an example that can be given is the preparation of Sr2Fe using the sol-gel method. 1.5-x Mo 0.5 Pt x O6.

[0006] Furthermore, the sol-gel method includes the following steps: (S1) Using strontium salt, iron salt, molybdenum salt and platinum salt as metal ion raw materials, they are mixed with citric acid, alcohol and deionized water, and then hydrolyzed and condensed to form a homogeneous solution; (S2) After aging and drying to remove moisture, a gel is obtained, and after a second drying, a novel double perovskite catalyst precursor is obtained; (S3) The precursor is subjected to a first calcination and a second calcination under a reducing atmosphere to obtain a novel double perovskite catalyst material Sr2Fe. 1.5-x Mo 0.5 Pt x O6.

[0007] In some embodiments of the present invention, the strontium salt, iron salt, molybdenum salt and platinum salt in step (S1) are soluble salts such as nitrates and chlorates. The nitrates are strontium nitrate, ferric nitrate, platinum nitrate, etc., and the other soluble salts are ammonium molybdate and chloroplatinic acid.

[0008] In a preferred embodiment of the present invention, the order of adding raw materials in step (S1) is preferably as follows: first, strontium salt, iron salt, molybdenum salt and citric acid are mixed; then, platinum salt is added and mixed; and finally, alcohol and deionized water are added.

[0009] Furthermore, in step (S1), the molar ratio of the sum of the metal ions to citric acid and alcohol is 2:3:6. The type of alcohol is not limited, such as ethylene glycol.

[0010] Furthermore, in step (S2), the pH of the homogeneous solution is adjusted to 1.3-1.7 using a pH adjuster, aged at a constant temperature of 60-100℃ for 5-7 hours, dried at 60-100℃ to remove moisture, and then dried a second time at 140-160℃. The type of pH adjuster is not limited, as long as it can achieve the pH adjustment function and does not participate in the reaction, such as ammonia.

[0011] Furthermore, in step (S3), the calcination temperature is 800~900℃, the heating rate is 3-5℃ / min, the calcination time is 4-7 hours, and the calcination atmosphere is air.

[0012] Furthermore, in step (S3), the temperature of the secondary calcination under a reducing atmosphere is 1100-1200℃, the heating rate is 3-5℃ / min, the calcination time is 3-5 hours, and the calcination atmosphere is a reducing atmosphere created by graphite.

[0013] A second aspect of the present invention provides an electrode material comprising the novel double perovskite catalytic material provided in the first aspect of the present invention.

[0014] In some embodiments of the present invention, the novel dual perovskite catalyst SF provided in the first aspect of the present invention... 1.5-x MPt x It can be used directly as an electrode material.

[0015] In other embodiments of the present invention, the novel dual perovskite catalyst SF provided in the first aspect of the present invention 1.5-x MPt x It can also be compounded with other materials for use as electrode materials. Among them, the other materials are SDC (representing samarium oxide-doped cerium oxide) and GDC (representing gadolinium oxide-doped cerium oxide).

[0016] The electrode material provided in the second aspect of this invention can be used as an electrode for solid oxide batteries and symmetrical batteries.

[0017] A third aspect of the present invention provides a solid oxide battery comprising the novel dual perovskite catalyst Sr2Fe described in the first aspect of the present invention. 1.5-x Mo 0.5 Pt x O6 (x≤0.01) is used as the electrode material. Preferably, the solid oxide battery is a solid oxide electrolyzer or a solid oxide fuel cell.

[0018] The beneficial effects of this invention are as follows: The novel double perovskite catalytic material provided by this invention, through appropriate platinum doping at the β-site of SFM (content less than 1%, molar content), has good electrical conductivity and catalytic activity, which can promote the methane-assisted water electrolysis reaction, reduce the ohmic resistance and polarization resistance of the electrode, and also reduce the overpotential required for the reaction, thereby increasing the power density of the battery; it provides a new approach to promoting methane-assisted water electrolysis by reducing the overpotential required for the reaction. Attached Figure Description

[0019] Figure 1 X-ray diffraction patterns of the double perovskite catalyst powders prepared in Comparative Examples 1 and 1-5; Figure 2 In the discharge mode, (a) shows the current density curves of the double perovskite catalyst materials prepared in Comparative Example 1 and Examples 1-5 as electrode materials; (b) shows the current-voltage curves of the double perovskite catalyst materials prepared in Comparative Example 1 and Examples 1-5 as electrode materials in the methane-assisted electrolysis mode. Detailed Implementation

[0020] This invention provides a novel double perovskite catalytic material, electrode material, and solid oxide battery. The invention will be further described below with reference to the embodiments.

[0021] Some specific embodiments of the present invention, the sol-gel method of the present invention for preparing Sr2Fe double perovskite catalyst. 1.5-x Mo 0.5 Pt x The specific steps for obtaining O6 (x≤0.01) material are as follows: (1) Weigh a certain amount of strontium nitrate, ferric nitrate, ammonium molybdate, chloroplatinic acid and citric acid and dissolve them in deionized water to obtain a solution; the amount of raw materials used in step (1) is weighed according to the molar ratio of metal ions to citric acid of 2:3.

[0022] (2) Mix the prepared solution evenly under stirring conditions, then add ethylene glycol, and add ammonia water dropwise while stirring to adjust the pH; the amount of raw materials used in step (2) is weighed according to the molar ratio of metal ions: citric acid: ethylene glycol of 2:3:6.

[0023] (3) After the pH is adjusted appropriately, the sol is obtained by sealing it with plastic wrap and stirring and aging it in a constant temperature water bath for a certain period of time. Then, the obtained sol is placed in a constant temperature drying oven to evaporate the water and obtain a gel. The pH in step (3) is maintained at 1.3-1.7. The stirring temperature of the constant temperature stirring water bath is 60-100℃ and the stirring time is 5-7 hours. The temperature of the constant temperature drying oven is 60-100℃.

[0024] (4) The gel is dried again to obtain a fluffy precursor. The precursor is ground and then placed in a rapid heating furnace for calcination to obtain an intermediate. The secondary drying temperature of the fluffy precursor in step (4) is 140-160℃. The calcination temperature of the intermediate is 800-900℃, the heating rate is 3-5℃ / min, the calcination time is 4-7 hours, and the calcination atmosphere is air.

[0025] (5) The intermediate is placed in a rapid heating furnace and calcined under a reducing atmosphere to obtain the finished catalyst material. The calcination temperature of the finished catalyst material in step (5) is 1100-1200℃, the heating rate is 3-5℃ / min, the calcination time is 3-5 hours, and the calcination atmosphere is a reducing atmosphere created by graphite.

[0026] Comparative Example 1 At room temperature, strontium nitrate (42.326 g, 211.63 g / mol), ferric nitrate nonahydrate (60.59958 g, 403.9972 g / mol), ammonium molybdate tetrahydrate (8.828 g, 1235.86 g / mol), and citric acid (115.78 g) were dissolved in deionized water. The prepared solutions were then mixed thoroughly and stirred at room temperature. Ethylene glycol (74.4816 g) was then added and stirred, with ammonia added dropwise continuously during stirring to maintain the pH at approximately 1.5. The solution was sealed with plastic wrap and stirred in a constant temperature water bath (80°C) for 5 hours to obtain a sol. After the reaction was complete, the sol was placed in an 80°C drying oven to evaporate excess water, yielding a gel. The gel was then heated to 150°C and burned to obtain a fluffy precursor. The precursor was ground into powder and calcined in an 800℃ rapid heating furnace (heating rate of 5℃ / min) for 4 hours in air to obtain an intermediate. Finally, the intermediate was calcined in an 1100℃ rapid heating furnace in a graphite-generated reducing atmosphere for 3 hours to obtain Sr2Fe. 1.5 Mo 0.5 O6 (corresponding to SFM).

[0027] Example 1

[0028] At room temperature, strontium nitrate (42.326 g), ferric nitrate nonahydrate (60.519 g), ammonium molybdate tetrahydrate (8.828 g), and citric acid (115.78 g) were dissolved separately in deionized water; then the prepared solutions were mixed thoroughly and stirred at room temperature; the concentration was increased to 1×10⁻⁶. -42 ml of chloroplatinic acid solution was added dropwise to the mixed solution and stirred until homogeneous. Ethylene glycol (74.4816 g) was then added and stirred. Ammonia was continuously added dropwise during stirring to maintain the pH at approximately 1.5. The solution was sealed with plastic wrap and stirred in a constant-temperature water bath (80°C) for 5 hours to obtain a sol. After the reaction was complete, the sol was placed in an 80°C drying oven to evaporate excess water, yielding a gel. The gel was then heated to 150°C and burned to obtain a fluffy precursor. The precursor was ground into powder and calcined in an 800°C rapid-heating furnace (heating rate 5°C / min) in air for 4 hours to obtain an intermediate. Finally, the intermediate was calcined in an 1100°C rapid-heating furnace in a graphite-generated reducing atmosphere for 3 hours to obtain Sr₂F. 1.498 Mo 0.5 Pt 0.002 O6 (SFM-2Pt).

[0029] Examples 2-5

[0030] Unlike Preparation Example 1, the amounts of ferric nitrate nonahydrate added were adjusted to 60.438 g, 60.357 g, 60.276 g, and 60.200 g, respectively, and the volumes of chloroplatinic acid solution added were correspondingly adjusted to 4 ml, 6 ml, 8 ml, and 10 ml. Finally, Sr₂F was obtained. 1.496 Mo 0.5 Pt 0.004 O6 (SFM-4Pt), Sr2F 1.494 Mo 0.5 Pt 0.006 O6 (SFM-6Pt), Sr2F 1.492 Mo 0.5 Pt 0.008 O6 (SFM-8Pt), Sr2F 1.49 Mo 0.5 Pt 0.01 O6 (SFM-10Pt).

[0031] The purity and crystallinity of the double perovskite catalytic materials prepared in Comparative Examples 1 and 1-5 were determined by X-ray diffraction (XRD), and the changes in diffraction peaks after Pt doping were observed. Figure 1 These are the XRD spectra of SFM and SFM doped with different Pt contents. From... Figure 1As can be seen from the comparison, the double perovskite catalysts SFM, SFM-2Pt, SFM-4Pt, SFM-6Pt, SFM-8Pt, and SFM-10Pt prepared in Examples 1 and 1-5 have no impurity phases, exhibiting high purity and good crystallinity. Furthermore, with the increase of platinum doping in SFM, the XRD diffraction peaks shifted towards higher angles, indicating that platinum ion doping leads to lattice contraction, resulting in smaller interplanar spacing, and platinum is well incorporated into SFM.

[0032] Experimental Example 1 The double perovskite catalysts prepared in Comparative Examples 1 and 1-5 were used to fabricate SFM-Pt+SDC||YSZ||Ni2O3 batteries for methane-assisted water electrolysis experiments. The test conditions were: temperature 800℃, anode-side atmosphere of methane (100 sccm), and cathode-side atmosphere of a mixture of water vapor and hydrogen (100 sccm, humidity 75%). Simultaneously, the discharge performance of the batteries with the above structure was tested under the following conditions: temperature 800℃, anode-side atmosphere of hydrogen, and cathode-side atmosphere of air. The results are as follows: Figure 2 As shown. Where SDC represents Sm 0.2 Ce 0.8 O 2-δ YSZ represents yttrium oxide stabilized zirconia material.

[0033] Figure 2 (a) shows the current density curves of the double perovskite catalyst materials prepared in Comparative Example 1 and Examples 1-5 as electrode materials under discharge mode; (b) shows the current-voltage curves of the double perovskite catalyst materials prepared in Comparative Example 1 and Examples 1-5 as electrode materials under methane-assisted electrolysis mode. Figure 2 As shown in Figure (b), among the materials SFM, SFM-2Pt, SFM-4Pt, SFM-6Pt, SFM-8Pt, and SFM-10Pt prepared by the method described in this invention, SFM-8Pt exhibits better electrochemical performance, possessing lower overpotential and polarization resistance during electrolysis. According to... Figure 2 As shown in Figure (a), among the materials SFM-2Pt, SFM-4Pt, SFM-6Pt, SFM-8Pt, and SFM-10Pt prepared by the method of the present invention, except for SFM-10Pt with a higher doping content, the other materials have higher power density and lower polarization resistance compared to SFM.

[0034] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A novel double perovskite catalytic material, characterized in that, Doping platinum in the β site of the catalytic material SFM, a new type of double perovskite catalytic material Sr2Fe 1.5-x Mo 0.5 Pt x O6, wherein x = 0.

004.

2. The novel dual perovskite catalytic material according to claim 1, characterized in that, Sr2Fe 1.5-x Mo 0.5 Pt x O6, the sol-gel method comprising the steps of: (S1) Using strontium salt, iron salt, molybdenum salt and platinum salt as metal ion raw materials, they are mixed with citric acid, alcohol and deionized water, and then hydrolyzed and condensed to form a homogeneous solution; (S2) After aging and drying to remove moisture, a gel is obtained, and after a second drying, a novel double perovskite catalyst precursor is obtained; (S3) the precursor is calcined once and calcined twice under a reducing atmosphere to obtain a new double perovskite catalytic material Sr2Fe 1.5-x Mo 0.5 Pt x O6.

3. The novel dual perovskite catalytic material according to claim 2, characterized in that, In step (S1), the sum of the molar amounts of metal ions is in a molar ratio of 2:3:6 to citric acid and alcohol.

4. The novel dual perovskite catalytic material according to claim 2, characterized in that, In step (S2), the pH of the homogeneous solution is adjusted to 1.3-1.7 using a pH adjuster, aged at a constant temperature of 60-100℃ for 5-7 hours, dried at 60-100℃ to remove moisture, and then dried a second time at 140-160℃.

5. The novel dual perovskite catalytic material according to claim 2, characterized in that, In step (S3), the calcination temperature is 800~900℃, the heating rate is 3-5℃ / min, the calcination time is 4-7 hours, and the calcination atmosphere is air.

6. The novel dual perovskite catalytic material according to claim 2, characterized in that, In step (S3), the temperature of the secondary calcination under the reducing atmosphere is 1100-1200℃, the heating rate is 3-5℃ / min, the calcination time is 3-5 hours, and the calcination atmosphere is a reducing atmosphere created by graphite.

7. An electrode material, characterized in that, The novel double perovskite catalytic material as described in any one of claims 1 to 6 is included.

8. A solid oxide battery, characterized in that, SF, comprising the novel double perovskite catalyst according to any one of claims 1 to 6 1.5-x MPt x As an electrode material.

9. The solid oxide battery according to claim 8, characterized in that, The solid oxide battery is either a solid oxide electrolyzer or a solid oxide fuel cell.

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