Ammonia solid oxide fuel cell anode catalyst rich in three-phase interface

Abstract

The invention discloses a Ni-based anode catalyst suitable for a direct ammonia solid oxide fuel cell (NH3-SOFC) as well as a preparation method and application of the Ni-based anode catalyst, and belongs to the technical field of preparation of anode materials of solid oxide fuel cells. The catalyst is composed of a fluorite phase change valence metal oxide solid solution with Ni nanoparticles dispersed on the surface, and the chemical composition of the catalyst is Ni / Ce < 1-x-y > Zr < x > Ni < y > O < 2-delta > (xlt; a sol-gel method is adopted for preparation, a nickel component is partially dissolved in a CeO2 matrix in a solid mode, and highly-dispersed nanoscale metal particles are formed after reduction. The unique metal-oxide synergistic structure enhances the interaction between Ni and the carrier, effectively inhibits nitridation of active sites and particle aggregation in the ammonia atmosphere, and constructs a stable three-phase interface. In addition, oxygen vacancies are introduced through Zr doping, and the catalytic activity and conductivity are further improved. The NH3-SOFC constructed based on the catalyst has excellent ammonia decomposition and oxidation activity, and has excellent electrochemical performance and long-term stability.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of solid oxide fuel cell anode materials, and specifically relates to a preparation method and application of a solid oxide fuel cell anode with high ammonia decomposition and ammonia oxidation performance and rich three-phase interface. Background Art

[0002] Hydrogen is regarded as an ideal clean energy carrier due to its high energy density and zero carbon emission characteristics, but its high storage and transportation costs limit its widespread application. In contrast, ammonia (NH3) has the advantages of zero carbon emissions, high hydrogen content, mature industrial chain and low cost, becoming an important alternative carrier of hydrogen energy and showing great potential in the field of energy conversion. Among them, solid oxide fuel cells (SOFCs) fueled by ammonia are considered to be an important development direction of clean energy technology in the future due to their high power generation efficiency and fuel adaptability. SOFC anode, as the core component for catalyzing the electrochemical oxidation of fuel gas, directly affects the output performance and long-term stability of the battery. However, when the traditional Ni-based anode is operated at high temperature, the metal Ni particles are prone to agglomeration and coarsening, resulting in a reduction in active sites, a decrease in catalytic activity, and accelerated battery performance degradation. In addition, the three-phase interface (TPB) of the traditional anode is mainly distributed at the electrode-electrolyte interface, which limits the electrochemical reaction area, resulting in higher ohmic impedance and polarization impedance, which seriously restricts the battery performance. Therefore, developing anode materials with rich three-phase interfaces, high catalytic activity and excellent stability is crucial to improving the performance of NH3-SOFC and promoting its commercial application.

[0003] Related research on ammonia decomposition catalysts shows that among non-precious metal systems, nickel (Ni) exhibits the best catalytic activity for ammonia decomposition due to its moderate nitrogen binding enthalpy. The valence state regulation ability of variable valence metal oxides in a high-temperature reducing atmosphere can effectively promote electron transfer. Among them, CeO2 has become a catalyst carrier of wide concern due to its excellent redox properties and high ionic conductivity. Doped CeO2 can further induce Ce in a high-temperature reducing environment. 4+ To Ce 3+ The transformation significantly improves the electronic and oxygen ion conductivity of the material, thereby enhancing its catalytic activity. In recent years, such metal-oxide composite catalysts have been proven to be potential candidate materials for NH3-SOFC anodes. However, the anode catalysts prepared by the traditional physical mixing sintering method have problems such as low three-phase interface concentration, limited active sites, and easy growth and aggregation of metal nickel particles, which limit the catalytic efficiency of ammonia decomposition. Therefore, how to construct a catalyst system with unique metal-oxide synergy to achieve more efficient and long-term stable catalytic performance has become one of the key scientific issues in the design of NH3-SOFC anode catalysts. Summary of the invention

[0004] The object of the present invention is to provide a preparation method and application of an anode of a solid oxide fuel cell with rich triple-phase interfaces and high ammonia decomposition and ammonia oxidation performance, so as to achieve high output performance, ammonia utilization rate and good long-term stability of the ammonia solid oxide fuel cell. The Ni / Ce 1-x-y Zr x Ni y O 2-δ (x < 0.5) catalyst is synthesized by a simple sol-gel method. Ni is uniformly dispersed on the surface of a high ionic conductivity carrier in the form of nanoparticles and forms a strong interaction with the carrier to construct a MIEC (mixed ion-electron conductor) anode catalyst with triple-phase interfaces widely distributed throughout the anode. By doping heteroatoms to construct oxygen vacancies, the ammonia decomposition and electrocatalytic activities of the catalyst are further optimized. Its preparation method is simple and the cost is low, providing an effective strategy for the design of anode catalysts for ammonia solid oxide fuel cells.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] An anode catalyst of a solid oxide fuel cell with rich triple-phase interfaces and high ammonia decomposition and ammonia oxidation performance, wherein the catalyst is a fluorite-type variable-valence metal oxide solid solution with Ni nanoparticles uniformly dispersed on the surface, denoted as Ni / Ce 1-x- y Zr x Ni y O 2-δ (x < 0.5).

[0007] A highly active anode catalyst of an ammonia solid oxide fuel cell with rich triple-phase interfaces, Ni / Ce 1-x-y Zr x Ni y O 2-δ (x < 0.5) and its preparation method, comprising the following steps:

[0008] (1) According to the stoichiometric requirements, dissolve a certain amount of Ni(NO3)3·6H2O, Ce(NO3)3·6H2O and Zr(NO3)4·5H2O in 50 - 100 ml of deionized water, stir evenly to dissolve, and obtain solution A;

[0009] (2) Add a certain amount of complexing agent into a beaker, add 100 ml of solvent for dissolution, and stir with a magnetic stirrer for 10 - 40 minutes, denoted as solution B;

[0010] (3) Quickly pour solution B in step (2) into solution A in step (1), continuously stir with a magnetic stirrer for 1 - 3 hours, then stop stirring, perform an oil bath, wait until the solvent evaporates completely, and the solution presents a transparent gel-like state, then stop heating and stirring;

[0011] (4) Cool the wet gel obtained in step (3) for 1 - 3 hours, then put it into an oven for drying, cooling, and grinding to obtain a variable-valence metal oxide precursor with uniformly dispersed nickel metal nanoparticles on the surface;

[0012] (5) Calcinate the precursor powder obtained in step (4) in an air atmosphere to obtain NiO / Ce 1-x-y Zr x Ni y O 2-δ (x < 0.5) composite oxide;

[0013] (6) Programmed temperature reduction of NiO / Ce 1-x-y Zr x Ni y O 2-δ (x < 0.5) obtained in step (5) in a reducing atmosphere, and then obtain a Ni / Ce anode catalyst with uniformly dispersed nickel metal nanoparticles on the surface and rich triple-phase boundaries 1-x-y Zr x Ni y O 2-δ (x < 0.5).

[0014] Furthermore, the complexing agent in step (2) is citric acid, and its addition amount is calculated according to the molar ratio of the complexing agent to the total metal cations of (1 - 2):1.

[0015] Furthermore, in step (3), the oil bath temperature is maintained at 80 - 140 °C for 4 - 6 hours.

[0016] Furthermore, in step (4), the temperature of the oven where the wet gel is placed is set at 80 - 140 °C for 12 - 24 hours.

[0017] Furthermore, in step (5), the calcination process is as follows: calcine at 300 - 450 °C for 1 - 2 hours, maintain the heating rate at 2 - 5 °C / min, then raise the temperature to 800 °C for calcination, maintain for 2 - 5 hours, and maintain the heating rate at 2 - 5 °C / min.

[0018] Furthermore, in step (6), the reducing atmosphere is a 50% (volume fraction) H2 / Ar mixed gas, the programmed temperature reduction temperature is 600 - 800 °C, and the calcination time is 3 - 6 hours.

[0019] Application of an anode catalyst with uniformly dispersed nickel metal nanoparticles on the surface and rich triple-phase boundaries in a direct ammonia solid oxide fuel cell, including the following steps:

[0020] (1) Add terpineol containing ethyl cellulose to the above catalyst Ni / Ce1-x-y Zr x Ni y O 2-δ (where \(x \lt 0.5\)), after thorough mixing, an anode slurry is obtained;

[0021] (2) The obtained anode slurry is brush-coated on the anode side of an electrolyte-supported half-cell with LSM as the cathode and YSZ as the electrolyte. The resulting single cell is sintered in a muffle furnace, and finally a direct ammonia solid oxide fuel cell single cell is obtained.

[0022] Furthermore, in step (1), the content of ethyl cellulose in the terpineol solution is 2 - 5 wt%, the calcination temperature of the cell after brush-coating the anode slurry is 800 - 1100 °C, the heating rate is 2 - 5 °C / min, and the calcination time is 2 - 5 hours.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] (1) The present invention provides a method for preparing and applying an anode of a solid oxide fuel cell with high ammonia decomposition and ammonia oxidation performance and rich triple-phase interfaces. The Ni / Ce 1-x-y Zr x Ni y O 2-δ (where \(x \lt 0.5\)) anode catalyst, Ni is partially dissolved in the CeO₂ matrix and forms highly dispersed nanoscale metal particles under high-temperature reduction conditions. This unique metal-oxide synergistic structure enhances the interaction between Ni and the support, effectively inhibits the nitridation and agglomeration of Ni in an ammonia atmosphere, maintains the high activity of the catalyst, and constructs a stable and rich triple-phase interface.

[0025] (2) The Zr doping regulation strategy in the present invention effectively promotes the conversion of Ce in the CeO₂ matrix 4+ to Ce 3+ , induces the formation of a large number of oxygen vacancies, significantly improves the oxygen ion conductivity, and accelerates the electron transfer between Ni and cerium oxide. This optimization not only enhances the kinetic characteristics of ammonia decomposition and oxidation reactions but also strengthens the metal-support interaction to a certain extent.

[0026] (3) Compared with traditional anodes that mainly rely on the electrode-electrolyte interface for electrochemical reactions, the present invention constructs a MIEC (mixed ion-electron conductor) anode catalyst with triple-phase interfaces widely distributed throughout the anode through oxygen vacancy regulation and uniform distribution of Ni nanoparticles, significantly reducing the ohmic impedance and polarization impedance of the cell, and improving the utilization rate of ammonia fuel and electrochemical performance.

[0027] (4) In the present invention, the efficient dispersion of Ni nanoparticles ensures the high activity of the catalyst, the MIEC property and oxygen vacancy regulation optimize the electron-ion transport path, and the metal-oxide synergistic structure effectively inhibits the agglomeration and deactivation of Ni. The present invention overcomes the problems of high-temperature instability and limited active sites of traditional Ni-based anodes through innovative design, providing a new research idea and implementation strategy for the development of efficient materials for NH3-SOFC anodes. Description of the Drawings

[0028] Figure 1 XRD patterns of different samples prepared in the examples and comparative examples of the present invention;

[0029] Figure 2 Ni / Ce obtained in Example 1 of the present invention 1-x-y Zr x Ni y O 2-δ SEM images of the (0.05 < x < 0.15, y < 0.1) anode catalyst;

[0030] Figure 3 TEM element distribution maps of the anode catalysts obtained in Example 1 and Comparative Example 4 of the present invention;

[0031] Figure 4 Ammonia decomposition performance diagrams of Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 4 of the present invention;

[0032] Figure 5 Cell current-voltage-power density curve diagram of the anode catalyst obtained in Example 3 of the present invention applied in direct ammonia SOFC. Detailed Description of the Invention

[0033] In order to make the content described in the present invention more understandable, the technical solutions of the present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

[0034] Example 1

[0035] S1. Weigh 1.46 g of Ni(NO3)3·6H2O, 7.38 g of Ce(NO3)3·6H2O, and 1.29 g of Zr(NO3)4·5H2O and dissolve them in 50 mL of deionized water, stir evenly to dissolve, and obtain solution A;

[0036] S2. According to the molar ratio of citric acid to total metal cations of 1.25:1, add 6 g of citric acid to a beaker, add 50 mL of deionized water to dissolve it, and stir with a magnetic stirrer for 30 minutes, denoted as solution B;

[0037] S3, quickly pour the B solution in S2 into the A solution in S1, stir with a magnetic stirrer for 1 hour, then stop stirring, and then place it in an 85°C oil bath for 4 hours, stirring and reacting, until the solvent evaporates completely and the solution becomes a transparent gel, stop heating and stirring;

[0038] S4, cooling the wet gel obtained in S3 for 1 hour, then putting it into an oven, drying it at 85° C. for 12 hours, cooling it, and grinding it to obtain a variable-valence metal oxide precursor with nickel metal nanoparticles uniformly dispersed on the surface;

[0039] S5, the precursor powder in S4 is heated to 450°C at a heating rate of 2°C / min and kept at this temperature for 2 hours to obtain a pretreated powder; then the precursor powder is heated to 800°C at a heating rate of 2°C / min and calcined for 2 hours to obtain NiO / Ce 1-x-y Zr x Ni y O 2-δ (0.05 <x<0.15,y<0.1)固溶体;

[0040] S6, the NiO / Ce obtained in S5 1-x-y Zr x Ni y O 2-δ (0.05 <x<0.15,y<0.1)以2℃ / min的升温速率升温至800℃于体积分数50%H2 / Ar混合气中还原3小时后,得到表面镍金属纳米颗粒均匀分散的具有丰富三相界面的Ni / Ce 1-x-y Zr x Ni y O 2-δ (0.05 <x<0.15,y<0.1)阳极催化剂。

[0041] S7, adding 4wt% ethyl cellulose to the catalyst Ni / Ce 1-x-y Zr x Ni y O 2-δ (0.05 <x<0.15,y<0.1)中,充分混合后,得到阳极浆料;

[0042] S8, brush the obtained anode slurry on the anode side of the electrolyte-supported half-cell sheet with LSM as cathode and 8YSZ as electrolyte, heat the obtained single cell to 800°C at 3°C / min and sinter for 2 hours, then cool to room temperature, and finally obtain a direct ammonia solid oxide fuel cell single cell sheet. For the convenience of the following description, the anode catalyst is recorded as 10Ni / CZO.

[0043] Example 2

[0044] The specific preparation method of this embodiment is basically the same as that of Example 1, except that 3.29 g of Ni(NO3)3·6H2O is added to S1 so that the mass fraction of Ni in the solid solution is 20%. The anode catalyst is recorded as 20Ni / CZO.

[0045] Example 3

[0046] S1. Weigh 1.46 g Ni(NO3)3·6H2O, 7.38 g Ce(NO3)3·6H2O and 1.29 g Zr(NO3)4·5H2O and dissolve them in 50 ml deionized water, stir and dissolve them evenly to obtain solution A.

[0047] S2, according to the molar ratio of citric acid to total metal cations being 1.25:1, 6.3 g of citric acid was added to a beaker, 50 ml of deionized water was added to dissolve, and stirred for 30 minutes using a magnetic stirrer, which was recorded as solution B;

[0048] S3, quickly pour the B solution in S2 into the A solution in S1, stir with a magnetic stirrer for 1 hour, then stop stirring, and then place it in an 85°C oil bath for 4 hours, stirring and reacting, until the solvent evaporates completely and the solution becomes a transparent gel, stop heating and stirring;

[0049] S4, cooling the wet gel obtained in S3 for 1 hour, then putting it into an oven, drying it at 85° C. for 12 hours, cooling it, and grinding it to obtain a variable-valence metal oxide precursor with nickel metal nanoparticles uniformly dispersed on the surface;

[0050] S5, the precursor powder in S4 is heated to 450°C at a heating rate of 2°C / min and kept at this temperature for 2 hours to obtain a pretreated powder; then the precursor powder is heated to 800°C at a heating rate of 2°C / min and calcined for 2 hours to obtain NiO / Ce 1-x-y Zr x Ni y O 2-δ (0.05 <x<0.15,y<0.1)复合氧化物;

[0051] S6, the NiO / Ce obtained in S5 1-x-y Zr x Ni y O 2-δ (0.05 <x<0.15,y<0.1)以2℃ / min的升温速率升温至800℃于体积分数50%H2 / Ar混合气中还原3小时后,得到表面镍金属纳米颗粒均匀分散的具有丰富三相界面的Ni / Ce 0.85 Zr 0.15 Ni δ O 2-x Anode catalyst.

[0052] S7, adding 4wt% ethyl cellulose to the catalyst Ni / Ce 1-x-y Zr x Ni y O 2-δ (0.05 <x<0.15,y<0.1)中,充分混合后,得到阳极浆料;

[0053] S8, apply the anode slurry obtained in S7 to the LSM cathode, (Sc2O3) 0.1 (CeO2) 0.01 (ZrO2) 0.89 The electrolyte supports the anode side of the half-cell sheet with (SSZ) as the electrolyte, and the obtained single cell is heated to 800°C at 3°C / min and sintered for 2h, then cooled to room temperature, and finally a direct ammonia solid oxide fuel cell single cell sheet is obtained.

[0054] Comparative Example 1

[0055] S1. Weigh 0.6 g of NiO powder and 0.4 g of YSZ in a mass fraction of 6:4 and mix them evenly. Add 4 wt % ethyl cellulose-containing pinene alcohol, pour into a mortar and mix thoroughly to obtain an anode slurry.

[0056] S2, brush the anode slurry obtained in S7 on the anode side of the electrolyte-supported half-cell sheet with LSM as cathode and YSZ as electrolyte, heat the obtained single cell to 1400°C at 3°C / min and sinter for 2 hours, then cool to room temperature, and finally obtain a direct ammonia solid oxide fuel cell single cell sheet. For the convenience of the following description, the anode is recorded as 60NiO / 40YSZ.

[0057] Comparative Example 2

[0058] S1. Weigh 7.38 g of Ce(NO3)3·6H2O and 1.31 g of Ni(NO3)3·6H2O and dissolve them in 50 mL of deionized water, stir and dissolve evenly to obtain solution A.

[0059] S2, according to the molar ratio of citric acid to total metal cations being 1.25:1, 5.16 g of citric acid was added to a beaker, 50 ml of deionized water was added to dissolve, and stirred for 30 minutes using a magnetic stirrer, which was recorded as solution B;

[0060] S3, quickly pour the B solution in S2 into the A solution in S1, stir with a magnetic stirrer for 1 hour, then stop stirring, and then place it in an 85°C oil bath for 4 hours, stirring and reacting, until the solvent evaporates completely and the solution becomes a transparent gel, stop heating and stirring;

[0061] S4. After cooling the wet gel obtained in S3 for 1 hour, place it in an oven and dry it at 85 °C for 12 hours. Then cool and grind it to obtain the NiO / Ce 1-x Ni x O 2-δ (x < 0.1) precursor;

[0062] S5. Heat the precursor powder in S4 at a heating rate of 2 °C / min to 450 °C and hold for 2 hours to obtain a pretreated powder. Then heat it at a heating rate of 2 °C / min to 800 °C and calcine for 2 hours to obtain the NiO / Ce 1-x Ni x O 2-δ (x < 0.1) oxide;

[0063] S6. Heat the NiO / Ce 1-x Ni x O 2-δ (x < 0.1) at a heating rate of 2 °C / min to 800 °C and reduce it in a 50% H2 / Ar mixed gas for 3 hours to obtain the Ni / Ce 1-x Ni x O 2-δ (x < 0.1) anode catalyst;

[0064] S7. Add terpineol containing 4 wt% ethyl cellulose to the above catalyst Ni / Ce 1-x Ni x O 2-δ (x < 0.1), mix well to obtain the anode paste;

[0065] S8. Brush the anode paste obtained in S7 on the anode side of the electrolyte-supported half-cell with LSM as the cathode and YSZ as the electrolyte. Heat the obtained single cell to 800 °C at a rate of 3 °C / min and sinter for 2 hours, then cool to room temperature. Finally, obtain the direct ammonia solid oxide fuel cell single cell. For the convenience of the following description, this anode is denoted as 10Ni / CeO2.

[0066] Comparative Example 3

[0067] S1. Weigh 7.38 g of Ce(NO3)3·6H2O and 1.29 g of Zr(NO3)4·5H2O, dissolve them in 50 ml of deionized water, and stir evenly to obtain solution A;

[0068] S2. According to the molar ratio of citric acid to total metal cations of 1.25:1, add 6.3 g of citric acid to a beaker, add 50 ml of deionized water for dissolution, and stir with a magnetic stirrer for 30 minutes, denoted as solution B;

[0069] S3. Quickly pour the B solution in S2 into the A solution in S1. After continuously stirring with a magnetic stirrer for 1 hour, stop stirring, and then place it in an oil bath at 85 °C and stir for 4 hours. Wait until the solvent has completely evaporated and the solution shows a transparent gel-like state, then stop heating and stirring;

[0070] S4. After cooling the wet gel obtained in S3 for 1 hour, put it into an oven and dry it at 85 °C for 12 hours, then cool and grind it to obtain the Ce 0.85 Zr 0.15 O 2-δ precursor;

[0071] S5. Heat the precursor powder in S4 at a heating rate of 2 °C / min to 450 °C and hold for 2 hours to obtain a pretreated powder; then heat it at a heating rate of 2 °C / min to 800 °C and calcine for 2 hours to obtain the Ce 0.85 Zr 0.15 O 2-δ oxide;

[0072] S6. Weigh 0.38 g of NiO powder and the above-obtained Ce 0.85 Zr 0.15 O 2-δ and pour them into an agate mortar for mixing. Use an agate pestle to mix and grind repeatedly for about 30 minutes until the color of the mixed powder is uniform and the mixing is complete; then add terpineol containing 4 wt% ethyl cellulose, pour it into the mortar and mix well to obtain the anode slurry.

[0073] S7. Brush the anode slurry obtained in S6 on the anode side of the electrolyte-supported half-cell with LSM as the cathode and YSZ as the electrolyte. Heat the obtained single cell to 800 °C at a rate of 3 °C / min and sinter for 2 hours, then cool to room temperature. Finally, obtain a direct ammonia solid oxide fuel cell single cell. For the convenience of subsequent description, this anode is denoted as 10Ni / CZO-IM.

[0074] Comparative Example 4

[0075] The specific implementation method is basically the same as that of Comparative Example 3, except for S5. Weigh 1.46 g of Ni(NO3)3·6H2O and dissolve it in 5 mL of deionized water, and ultrasonicate for 15 minutes; drop it into the previously prepared Ce 0.85 Zr 0.15 O2 in 3 - 4 portions, dry it in portions under an infrared lamp, and then heat it at a heating rate of 2 °C / min to 800 °C and calcine for 2 hours to obtain Ni / Ce 0.85 Zr 0.15 O 2-δ -IM. For the convenience of subsequent description, this anode is denoted as 10Ni / CZO-IM.

[0076] Product performance test:

[0077] Before the single cell assembly, a thin silver paste (5×5 mm grid) was screen-printed on the cathode side as the current collector. Single cell assembly: Place the cell on the reactor, and place nickel mesh and silver mesh at both ends of the anode and cathode of the cell respectively. On this basis, place two silver wires respectively to ensure close contact between components. Then, apply silver paste between the nickel mesh and the silver wire, and between the silver mesh and the silver wire to further ensure the tightness of the connection. Finally, seal the joints of the reactor with ceramic adhesive to isolate the anode and cathode gases and ensure the airtightness of the device. The performance of the fuel cell was measured by the two-electrode method, and the positive and negative electrodes of the electrochemical workstation (Zahner IM6) were connected with silver wires. Under laboratory conditions, 50 Sccm of NH3 was introduced, and the output power density and electrochemical impedance spectrum of the obtained fuel cell at 600 °C - 800 °C were tested using the IM6 electrochemical analyzer.

[0078] Figure 1 For the XRD patterns of each sample, the diffraction peaks belonging to CeO2 with a fluorite structure can be found, corresponding to its (111), (200), (220), (311) and (222) crystal planes. In the XRD of the sample Ni-CZO-M with Ni introduced by mechanical mixing method, the diffraction peaks of NiO can be clearly observed. In contrast, the diffraction peaks of NiO in the XRD of the sample Ni-CZO-IM with Ni introduced by impregnation method are weaker, while almost no diffraction peaks of NiO can be found in the XRD of the Ni-CZO sample with Ni introduced by sol-gel method, indicating that the Ni component is more uniformly dispersed in the catalyst.

[0079] Figure 2 This is the SEM image of Ni-CZO. It can be observed that Ni nanoparticles with a size of 20 - 30 nm are uniformly distributed on its surface. Figure 3 This is the TEM element distribution map of the prepared Ni-CZO and Ni-CZO-IM. In contrast, the Ni particles in Ni-CZO have a smaller particle size and a more uniform distribution.

[0080] Figure 4 This shows the ammonia decomposition performance diagrams of Example 1 and several comparative examples. It can be seen from the figure that Example 1 has the highest ammonia decomposition performance, and its ammonia decomposition rate at 600 °C is 90%, and it reaches complete decomposition at 650 °C, indicating that this catalyst has excellent catalytic activity for ammonia decomposition.

[0081] Figure 5 This shows the current-voltage-power density characteristic curve of the anode catalyst prepared in Example 3 in a direct ammonia SOFC. The results show that in an NH3 atmosphere at 800 °C, the peak power density of this cell is close to 600 mW·cm -2, showing excellent output performance. At the same time, its electrochemical performance under ammonia fuel conditions is close to that under hydrogen fuel conditions, indicating that the catalyst has excellent ammonia decomposition and ammonia oxidation activities, providing strong support for the development of high-efficiency direct ammonia SOFCs.

[0082] Table 1 Power density of direct ammonia solid oxide fuel cell at 800 °C

[0083]

[0084] It can be seen from the data analysis in Table 1 that: ① When the content of Ni is increased, the battery performance is further improved. The increase of metallic Ni will improve the electronic conductivity of the catalyst and enrich the catalytic reaction active sites; ② Compared with the 10Ni / CeO2 anode catalyst without Zr element doping, after Zr element doping, it enters the CeO2 lattice, increasing the oxygen vacancy concentration, greatly improving its conductivity and catalytic ability, making it a mixed ionic-electronic conductor (MIEC) with both ion-conducting and electron-conducting abilities; ③ Through the study of different introduction methods of Ni, compared with the 10Ni / CZO-M anode catalyst prepared by mechanical mixing method and the 10Ni / CZO-IM anode catalyst prepared by impregnation method, the 10Ni / CZO anode catalyst has the optimal output power, with smaller and more dispersed Ni nanoparticles, and a more abundant anode triple-phase boundary (the region where fuel gas, oxygen ion conductor, and electron-conducting phase contact), which is more conducive to the progress of electrochemical reactions; ④ Compared with the currently most common NiO / YSZ anode material, the prepared 10Ni / CZO anode catalyst has a significant increase in output power, and the power density is three times that of common commercial anodes under the same conditions, proving that the design strategy of this catalyst is effective and a high-catalytic-activity anode catalyst has been successfully prepared.

[0085] The above are only the preferred embodiments of the present invention. All equivalent changes and treatments made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims

1. An anode catalyst for an ammonia solid oxide fuel cell with a rich three-phase interface, characterized in that: The catalyst is a fluorite-phase valence metal oxide solid solution with Ni nanoparticles uniformly dispersed on the surface, and its chemical formula is Ni / Ce 1-x-y Zr x Ni y O 2-δ , where x < 0.

5.

2. A method for preparing the catalyst as described in claim 1, characterized in that: It includes the following steps: Dissolve Ni(NO3)3·6H2O, Ce(NO3)3·6H2O and Zr(NO3)4·5H2O in deionized water, stir evenly to obtain solution A; Dissolve the complexing agent in a solvent, stir magnetically for 10 - 40 minutes to obtain solution B; Quickly pour solution B into solution A, stir magnetically for 1 - 3 hours, heat in an oil bath to completely evaporate the solvent to obtain a wet gel; Cool the wet gel for 1 - 3 hours, then dry, cool and grind to obtain a variable - valence metal oxide precursor with uniformly dispersed nickel metal nanoparticles on the surface; The precursor obtained in step (4) is calcined in an air atmosphere to obtain a composite oxide NiO / Ce 1-x-y Zr x Ni y O 2-δ， x < 0.5; (6) Subject the composite oxide NiO / Ce 1-x-y Zr x Ni y O 2-δ， x < 0.5 obtained in step (5) to a reduction reaction in a reducing atmosphere to obtain the anode catalyst of the ammonia solid oxide fuel cell rich in triple-phase boundaries.

3. The method according to claim 2, characterized in that: In step (2), the complexing agent is citric acid, and the molar ratio of the complexing agent to the total metal cations in step (1) is 1~2:

1.

4. The method according to claim 2, wherein: In step (3), the oil bath temperature is 80 - 140 °C and the time is 4 - 6 hours.

5. The method according to claim 2, wherein: In step (4), the drying temperature is 80 - 140 °C and the time is 12 - 24 hours.

6. The method according to claim 2, wherein: In step (5), the calcination process is as follows: the heating rate is 2 - 5 °C / min, calcine at 300 - 450 °C for 1 - 2 hours, and then raise the temperature to 800 °C and calcine for 2 - 5 hours.

7. The method according to claim 2, characterized in that: In step (6), the reducing atmosphere is a mixed gas of H2 and Ar with a volume ratio of 1:1; the reduction temperature is 600 - 800 °C and the time is 3 - 6 hours.

8. Application of a triple - phase - boundary - rich ammonia solid oxide fuel cell anode catalyst as described in claim 1 or a triple - phase - boundary - rich ammonia solid oxide fuel cell anode catalyst prepared by the method as described in any one of claims 2 - 7 in a direct ammonia solid oxide fuel cell.

9. The application according to claim 8, wherein: It includes the following steps: (1) Add the terpineol containing ethyl cellulose to the catalyst Ni / Ce 1-x-y Zr x Ni y O 2-δ， where x < 0.

5. After thorough mixing, an anode paste is obtained; (2) Brush the anode paste on the anode side of an electrolyte - supported half - cell with LSM as the cathode and YSZ as the electrolyte, and sinter to obtain a single cell of a direct ammonia solid oxide fuel cell.

10. The application according to claim 9, wherein: The content of ethyl cellulose in terpineol is 2~5 wt%; the sintering temperature is 800~1100 °C, the time is 2~5 hours, and the heating rate is 2~5 °C / min.

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