A solid oxide fuel cell anode material based on zinc trap sites for direct ammonia efficient electrochemical oxidation, and a preparation method and application thereof

Abstract

This invention discloses a solid oxide fuel cell anode material and its preparation method based on zinc trap sites for direct, efficient electrochemical oxidation of ammonia. First, zinc-free Pr is prepared. 0.9 Cr 0.8 Ni 0.2 O 3‑δ The precursor, through zinc source impregnation and stepwise heat treatment, incorporates Zn 2+ By introducing partial substitution of Cr at the B-site of perovskite, zinc-doped perovskite material Pr is obtained. 0.9 Cr 0.8‑x Ni 0.2 Zn x O 3‑δ (0≤x≤0.4). This material, under a reducing atmosphere, Zn... 2+ The anode material, stably dissolved in the crystal lattice, forms strong Lewis acid "zinc trap" sites, which can specifically adsorb and activate ammonia molecules; simultaneously, it induces a high concentration of oxygen vacancies, optimizing the charge transfer process. These synergistic effects significantly enhance the catalytic activity of the anode for ammonia fuel, with a substantial reduction in electrochemical impedance in the mid-to-low temperature range. This phenomenon is presumably related to a shift in the reaction pathway towards the highly efficient "direct electrochemical oxidation of ammonia." The fabricated anode material achieves a power density of 292 mW / cm³ at 800℃ using pure ammonia as fuel. 2 It has good power output performance.

Description

Technical Field

[0001] This invention belongs to the field of preparation of anode catalysts for solid oxide direct ammonia fuel cells, specifically relating to a solid oxide fuel cell anode material, preparation method, and application that achieves efficient direct ammonia electrochemical oxidation based on zinc trap sites. Background Technology

[0002] Solid oxide fuel cells (SOFCs) are highly efficient clean energy conversion devices with high energy conversion rates, wide fuel adaptability, and an all-solid-state structure. They can directly convert the chemical energy of fuel into electrical energy and have broad prospects in distributed power generation and clean energy utilization. Ammonia (NH3) is considered a promising new SOFC fuel due to its high hydrogen content, easy liquefaction and storage, and carbon-free characteristics. However, the development of efficient direct ammonia SOFCs (DA-SOFCs) faces the core challenge that the catalytic oxidation activity of traditional nickel-based anodes for NH3 is far lower than that for H2, leading to poor battery performance. This gap mainly stems from: First, the slow activation kinetics of NH3 molecules. The breaking of NH bonds in NH3 requires high energy, and traditional anode materials lack specific active sites for efficient adsorption and activation of NH3, causing the initial reaction step to become the rate-controlling step. Second, the "hydrogen poisoning" effect interferes. The intermediate product H* produced by NH3 decomposition competes with NH3 molecules for surface active sites, inhibiting the continuous adsorption and reaction of NH3 and severely reducing the effective utilization rate of ammonia. To improve anode performance, researchers often employ a strategy of doping perovskite structures and inducing in-situ precipitation of active metals (such as Ni). However, traditional doping approaches tend to focus on adjusting oxygen vacancy concentrations or improving metal particle dispersion, paying insufficient attention to optimizing the adsorption and activation of NH3 molecules. If the initial activation of ammonia molecules can be enhanced by designing specific adsorption sites, it is hoped that the anode reaction can be driven towards a more efficient direct oxidation pathway. Summary of the Invention

[0003] The purpose of this invention is to address the shortcomings of existing technologies by providing a solid oxide fuel cell anode material, its preparation method, and its application based on zinc trap sites for direct and efficient electrochemical oxidation of ammonia. Zn 2+ Introducing Pr 0.9 Cr 0.8 Ni 0.2 O 3-δ The substitution of Cr at the B site in perovskite, in the reducing working atmosphere of the fuel cell anode, allows Zn to... 2+ As a strong Lewis acidic site, it is stably dissolved in the perovskite lattice to form a "zinc trap," while simultaneously inducing a high concentration of oxygen vacancies in the material. The power output density of the fabricated material at 800°C with pure ammonia fuel is close to that of pure hydrogen fuel, and the electrochemical impedance at 600°C with pure ammonia fuel is lower than that of pure hydrogen fuel. This gives the solid oxide direct ammonia fuel cell anode excellent ammonia catalytic activity and high ammonia utilization rate.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for efficient direct electrochemical oxidation of ammonia includes the following steps:

[0006] (1) Synthesis of zinc-free precursor: Weigh praseodymium source, chromium source and nickel source, dissolve in deionized water, add citric acid monohydrate as complexing agent, stir and mix at room temperature, heat and stir until the solvent is completely evaporated to obtain transparent gel; dry and grind the transparent gel, and pre-calcine it at a programmed temperature in air atmosphere to obtain PCN precursor, i.e. zinc-free precursor;

[0007] (2) Zinc source impregnation: Zinc source is dissolved in solvent to prepare impregnation solution, which is added dropwise to PCN precursor and heated and stirred until the solvent is completely evaporated to obtain Zn / PCN intermediate;

[0008] (3) Phase formation in an oxidizing atmosphere: The Zn / PCN intermediate is calcined in an air atmosphere with a programmed temperature increase to obtain perovskite-type praseodymium-chromium-nickel-zinc composite oxide; at this time, the zinc species are partially dissolved in the perovskite lattice, and the rest exist in the form of impurity phases such as ZnO;

[0009] (4) Reduction Atmosphere Treatment: The perovskite-type praseodymium-chromium-nickel-zinc composite oxide is reduced by programmed temperature rise under a H2 / Ar mixed atmosphere to obtain praseodymium-chromium-nickel-zinc-based perovskite oxide with metallic Ni nanoparticles loaded on the surface, which is a solid oxide fuel cell anode material based on zinc trap sites to achieve direct and efficient electrochemical oxidation of ammonia. In this process, zinc species undergo secondary solid solution, migrate into the B sites of the perovskite lattice and stabilize in solid solution, forming "zinc trap" sites; at the same time, a large number of oxygen vacancies are generated and some Ni is reduced to metallic nanoparticles.

[0010] Specifically, based on praseodymium, chromium, nickel, and zinc elements, the molar ratio of the praseodymium source, chromium source, nickel source, and zinc source satisfies the following relationship: praseodymium:chromium:nickel:zinc = 0.9:0.8-x:0.2:x, where 0 < x ≤ 0.4; the praseodymium source, chromium source, nickel source, and zinc source are metal salts, and the metal salts are any one or more of nitrates, acetates, and chlorides; the molar ratio of the monohydrated citric acid to the total amount of metal ions contained in the praseodymium source, chromium source, and nickel source is 1.2~2:1.

[0011] In step (1), the drying conditions are: drying at 150~180℃ for 15~18 hours; the preheating conditions are: heating from room temperature to 500~600℃ at a heating rate of 2~5℃ / min for 2~5 hours.

[0012] In step (2), the solvent is deionized water or an aqueous ethanol solution; the heating and stirring conditions are: magnetic stirring at 200-500 r / min at 60-90℃.

[0013] In step (3), the conditions for the programmed temperature rise calcination are: heating from room temperature to 1000-1100℃ at a heating rate of 2-5℃ / min for 2-5 hours.

[0014] In step (4), the reducing atmosphere is a H2 / Ar mixed atmosphere; the conditions for the programmed temperature reduction are: heating from room temperature to 800℃ at a heating rate of 2~5℃ / min for 2~8 hours.

[0015] A solid oxide fuel cell anode material based on zinc trap sites for direct and efficient electrochemical oxidation of ammonia is prepared by the above-described method.

[0016] The solid oxide fuel cell anode material is a perovskite matrix with Zn dissolved in it. 2+ It has strong Lewis acid zinc trap sites, and the matrix surface is uniformly dispersed with in-situ precipitated metallic Ni nanoparticles.

[0017] The above-mentioned solid oxide fuel cell anode material is used in solid oxide fuel cells that use pure ammonia as fuel.

[0018] The above-mentioned method for preparing the slurry of solid oxide fuel cell anode material involves mixing solid oxide fuel cell anode material and YSZ at a mass ratio of 4~6:6~4, grinding until uniform, adding terpineol containing 4wt% ethyl cellulose, and grinding until smooth and viscous to obtain the slurry of solid oxide fuel cell anode material.

[0019] The significant advantages of this invention are:

[0020] (1) The strong Lewis acidity of the "zinc trap" site preferentially and strongly adsorbs NH3, effectively inhibiting the competitive adsorption of intermediate product H* (i.e. "hydrogen poisoning") and improving ammonia utilization.

[0021] (2) Zn 2+ As a low-valence element, doping increases the Cr content in the crystal lattice. 6+ / Cr 4+ and Pr 4+ / Pr 3+ The content of redox ion pairs increases, thereby increasing the oxygen vacancy concentration;

[0022] (3) The synergistic effect significantly improved the catalytic performance of the anode for pure ammonia fuel in the low-temperature range (600℃), and the polarization resistance was greatly reduced. This significant performance improvement suggests that the anode reaction may have shifted from the traditional "ammonia decomposition-hydrogenation" pathway to a more efficient "direct electrochemical oxidation of ammonia" pathway. Attached Figure Description

[0023] Figure 1 XRD pattern of the anode material before reduction (a); XRD pattern of the anode material after reduction (b).

[0024] Figure 2 Py-IR spectra of the anode material. Adsorption of pyridine at 30℃ (a); desorption of pyridine at 30℃ (b); desorption of pyridine at 100℃ (c).

[0025] Figure 3 Impedance spectra of fuel cells using pure ammonia as fuel at 600~800℃ (a); Impedance spectra of fuel cells using anode material in Example 1 at 600℃ in different atmospheres (b). Detailed Implementation

[0026] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0027] Example 1:

[0028] In this embodiment, based on praseodymium, chromium, nickel, and zinc elements, the molar ratio of the praseodymium source, chromium source, nickel source, and zinc source satisfies the following relationship: praseodymium:chromium:nickel:zinc = 0.9:0.8-x:0.2:x, where x = 0.3.

[0029] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for efficient direct electrochemical oxidation of ammonia includes the following steps:

[0030] (1) Synthesis of zinc-free precursors:

[0031] Weigh 7.8302 g of praseodymium nitrate hexahydrate, 1.1632 g of nickel nitrate hexahydrate, and 4.0015 g of chromium nitrate nonahydrate, and dissolve them in 150 mL of deionized water to obtain solution A. Weigh citric acid monohydrate according to a molar ratio of 1.2:1 to the total amount of praseodymium, nickel, and chromium metal ions in solution A, and dissolve it in 50 mL of deionized water to obtain solution B. Add solution B to solution A and stir magnetically at 200 r / min for 60 minutes at room temperature to obtain a mixed solution. Stir the mixed solution magnetically at 200 r / min at 80 °C until the solvent is completely evaporated to obtain a transparent gel. Dry the transparent gel at 150 °C for 18 hours, then allow it to cool naturally to room temperature, and grind it to obtain a gel powder. The obtained gel powder was pre-calcined in air at a heating rate of 2℃ / min from room temperature to 600℃ for 2 hours to obtain the Pr-Cr-Ni precursor, also known as the PCN precursor or zinc-free precursor.

[0032] (2) Zinc source impregnation:

[0033] Weigh 1.785 g of zinc nitrate hexahydrate and dissolve it in 100 mL of deionized water to obtain an impregnation solution. Add the obtained impregnation solution dropwise to the zinc-free precursor obtained in step (1) and stir magnetically at 200 r / min at 80 °C until the solvent is completely evaporated to obtain a Zn / PCN intermediate.

[0034] (3) Phase formation in an oxidizing atmosphere:

[0035] The Zn / PCN intermediate obtained in step (2) was calcined in air at a heating rate of 2 °C / min from room temperature to 1100 °C for 2 hours, and then allowed to cool naturally to room temperature to obtain perovskite-type praseodymium-chromium-nickel-zinc composite oxide Pr. 0.9 Cr 0.5 Ni 0.2 Zn 0.3 O 3-δ .

[0036] (4) Reducing atmosphere treatment:

[0037] The perovskite-type praseodymium-chromium-nickel-zinc composite oxide Pr obtained in step (3) 0.9 Cr 0.5 Ni 0.2 Zn 0.3 O 3-δ Praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with surface-loaded Ni nanoparticles was obtained by reducing the oxide at a heating rate of 3 °C / min from room temperature to 800 °C for 5 hours under a mixed atmosphere of H2 / Ar (H2:Ar volume ratio 1:1). 0.9 Cr 0.5 Zn 0.3 O 3-δThis refers to solid oxide fuel cell anode materials that achieve direct and efficient electrochemical oxidation of ammonia based on zinc trap sites.

[0038] Example 2:

[0039] In this embodiment, the molar ratio of praseodymium source, chromium source, nickel source and zinc source, calculated by praseodymium, chromium, nickel and zinc elements, satisfies the following relationship: praseodymium:chromium:nickel:zinc = 0.9:0.8-x:0.2:x, where x=0.1.

[0040] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct high-efficiency electrochemical oxidation of ammonia is disclosed. The specific preparation steps are basically the same as in Example 1, with the only difference being: in step (1), 5.6021 g of chromium nitrate nonahydrate is weighed (replacing 4.0015 g of chromium nitrate nonahydrate in Example 1); in step (2), 0.595 g of zinc nitrate hexahydrate is weighed (replacing 1.785 g of zinc nitrate hexahydrate in Example 1). Correspondingly, the product obtained in step (3) is a perovskite-type praseodymium-chromium-nickel-zinc composite oxide (Pr). 0.9 Cr 0.7 Ni 0.2 Zn 0.1 O 3-δ The product obtained in step (4) is a praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with metallic Ni nanoparticles loaded on its surface. 0.9 Cr 0.7 Zn 0.1 O 3-δ .

[0041] Example 3:

[0042] In this embodiment, based on praseodymium, chromium, nickel, and zinc, the molar ratio of the praseodymium source, chromium source, nickel source, and zinc source satisfies the following relationship: praseodymium:chromium:nickel:zinc = 0.9:0.8-x:0.2:x, where x = 0.2.

[0043] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct high-efficiency electrochemical oxidation of ammonia is disclosed. The specific preparation steps are basically the same as in Example 1, with the only difference being: 4.8018 g of chromium nitrate nonahydrate is weighed (replacing 4.0015 g of chromium nitrate nonahydrate in Example 1); in step (2), 1.19 g of zinc nitrate hexahydrate is weighed (replacing 1.785 g of zinc nitrate hexahydrate in Example 1). Correspondingly, the product obtained in step (3) is a perovskite-type praseodymium-chromium-nickel-zinc composite oxide (Pr). 0.9 Cr 0.6 Ni 0.2 Zn 0.2 O 3-δThe product obtained in step (4) is a praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with metallic Ni nanoparticles loaded on its surface. 0.9 Cr 0.6 Zn 0.2 O 3-δ .

[0044] Example 4:

[0045] In this embodiment, the molar ratio of praseodymium source, chromium source, nickel source and zinc source, calculated by praseodymium, chromium, nickel and zinc elements, satisfies the following relationship: praseodymium:chromium:nickel:zinc = 0.9:0.8-x:0.2:x, where x=0.4.

[0046] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct high-efficiency electrochemical oxidation of ammonia is disclosed. The specific preparation steps are basically the same as in Example 1, with the only difference being: 3.2012 g of chromium nitrate nonahydrate is weighed (replacing 4.0015 g of chromium nitrate nonahydrate in Example 1); in step (2), 2.38 g of zinc nitrate hexahydrate is weighed (replacing 1.785 g of zinc nitrate hexahydrate in Example 1). Correspondingly, the product obtained in step (3) is a perovskite-type praseodymium-chromium-nickel-zinc composite oxide (Pr). 0.9 Cr 0.4 Ni 0.2 Zn 0.4 O 3-δ The product obtained in step (4) is a praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with metallic Ni nanoparticles loaded on its surface. 0.9 Cr 0.4 Zn 0.4 O 3-δ .

[0047] Example 5:

[0048] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct high-efficiency electrochemical oxidation of ammonia is disclosed. The specific preparation steps are basically the same as in Example 1, except that in step (1), corresponding molar amounts of praseodymium chloride, nickel chloride, and chromium chloride (consistent with the molar amounts of praseodymium nitrate hexahydrate, nickel nitrate hexahydrate, and chromium nitrate nonahydrate in Example 1) are weighed to replace the original hexahydrate nitrate. Correspondingly, the product obtained in step (3) is a perovskite-type praseodymium-chromium-nickel-zinc composite oxide Pr 0.9 Cr 0.5 Ni 0.2 Zn 0.3 O 3-δ The product obtained in step (4) is a praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with metallic Ni nanoparticles loaded on its surface. 0.9 Cr 0.5 Zn 0.3 O3-δ .

[0049] Example 6:

[0050] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct high-efficiency electrochemical oxidation of ammonia is disclosed. The specific preparation steps are basically the same as in Example 1, except that in step (1), praseodymium acetate, nickel chloride, and chromium chloride (with the same molar amounts of metal ions as praseodymium nitrate hexahydrate, nickel nitrate hexahydrate, and chromium nitrate nonahydrate in Example 1) are weighed to replace the original hexahydrate nitrate. Correspondingly, the product obtained in step (3) is a perovskite-type praseodymium-chromium-nickel-zinc composite oxide Pr 0.9 Cr 0.5 Ni 0.2 Zn 0.3 O 3-δ The product obtained in step (4) is a praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with metallic Ni nanoparticles loaded on its surface. 0.9 Cr 0.5 Zn 0.3 O 3-δ .

[0051] Example 7:

[0052] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct high-efficiency electrochemical oxidation of ammonia is disclosed. The specific preparation steps are basically the same as in Example 1, except that in step (1), the molar ratio of citric acid monohydrate to the total metal ions of praseodymium, nickel, and chromium in solution A is changed from 1.2:1 to 1.5:1. Correspondingly, the product obtained in step (3) is a perovskite-type praseodymium-chromium-nickel-zinc composite oxide (Pr). 0.9 Cr 0.5 Ni 0.2 Zn 0.3 O 3-δ The product obtained in step (4) is a praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with metallic Ni nanoparticles loaded on its surface. 0.9 Cr 0.5 Zn 0.3 O 3-δ .

[0053] Example 8:

[0054] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct high-efficiency electrochemical oxidation of ammonia is disclosed. The specific preparation steps are basically the same as in Example 1, except that in step (1), the molar ratio of citric acid monohydrate to the total metal ions of praseodymium, nickel, and chromium in solution A is changed from 1.2:1 to 2:1. Correspondingly, the product obtained in step (3) is a perovskite-type praseodymium-chromium-nickel-zinc composite oxide (Pr). 0.9 Cr0.5 Ni 0.2 Zn 0.3 O 3-δ The product obtained in step (4) is a praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with metallic Ni nanoparticles loaded on its surface. 0.9 Cr 0.5 Zn 0.3 O 3-δ .

[0055] Example 9:

[0056] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct high-efficiency electrochemical oxidation of ammonia is disclosed. The specific preparation steps are basically the same as in Example 1, except that in step (1), the gel drying temperature is changed from 150℃ to 180℃. Correspondingly, the product obtained in step (3) is a perovskite-type praseodymium-chromium-nickel-zinc composite oxide (Pr). 0.9 Cr 0.5 Ni 0.2 Zn 0.3 O 3-δ The product obtained in step (4) is a praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with metallic Ni nanoparticles loaded on its surface. 0.9 Cr 0.5 Zn 0.3 O 3-δ .

[0057] Example 10:

[0058] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct, efficient electrochemical oxidation of ammonia is disclosed. The specific preparation steps are basically the same as in Example 1, except that in step (1), the gel drying time is changed from 18 hours to 15 hours. Correspondingly, the product obtained in step (3) is a perovskite-type praseodymium-chromium-nickel-zinc composite oxide (Pr). 0.9 Cr 0.5 Ni 0.2 Zn 0.3 O 3-δ The product obtained in step (4) is a praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with metallic Ni nanoparticles loaded on its surface. 0.9 Cr 0.5 Zn 0.3 O 3-δ .

[0059] Example 11:

[0060] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct high-efficiency electrochemical oxidation of ammonia is disclosed. The specific preparation steps are basically the same as in Example 1, except that in step (1), the pre-calcination temperature is changed from 600℃ to 500℃. Correspondingly, the product obtained in step (3) is a perovskite-type praseodymium-chromium-nickel-zinc composite oxide (Pr). 0.9 Cr 0.5 Ni 0.2 Zn 0.3 O 3-δ The product obtained in step (4) is a praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with metallic Ni nanoparticles loaded on its surface. 0.9 Cr 0.5 Zn 0.3 O 3-δ .

[0061] Example 12:

[0062] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct high-efficiency electrochemical oxidation of ammonia is disclosed. The specific preparation steps are basically the same as in Example 1, except that in step (1), the pre-burning time is changed from 2 hours to 5 hours. Correspondingly, the product obtained in step (3) is a perovskite-type praseodymium-chromium-nickel-zinc composite oxide (Pr). 0.9 Cr 0.5 Ni 0.2 Zn 0.3 O 3-δ The product obtained in step (4) is a praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with metallic Ni nanoparticles loaded on its surface. 0.9 Cr 0.5 Zn 0.3 O 3-δ .

[0063] Example 13:

[0064] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct high-efficiency electrochemical oxidation of ammonia is disclosed. The specific preparation steps are basically the same as in Example 1, except that in step (2), a corresponding molar amount of zinc chloride (consistent with the molar amount of zinc nitrate hexahydrate metal ions in Example 1) is weighed to replace the original zinc nitrate hexahydrate. Correspondingly, the product obtained in step (3) is a perovskite-type praseodymium-chromium-nickel-zinc composite oxide (Pr). 0.9 Cr 0.5 Ni 0.2 Zn 0.3 O 3-δ The product obtained in step (4) is a praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with metallic Ni nanoparticles loaded on its surface. 0.9 Cr 0.5 Zn 0.3 O3-δ .

[0065] Example 14:

[0066] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct, high-efficiency electrochemical oxidation of ammonia is disclosed. The specific preparation steps are basically the same as in Example 1, except that in step (2), deionized water is replaced with an equal volume of 25 vol% ethanol aqueous solution. Correspondingly, the product obtained in step (3) is a perovskite-type praseodymium-chromium-nickel-zinc composite oxide (Pr). 0.9 Cr 0.5 Ni 0.2 Zn 0.3 O 3-δ The product obtained in step (4) is a praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with metallic Ni nanoparticles loaded on its surface. 0.9 Cr 0.5 Zn 0.3 O 3-δ .

[0067] Example 15:

[0068] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct high-efficiency electrochemical oxidation of ammonia is disclosed. The specific preparation steps are basically the same as in Example 1, except that in step (2), the magnetic stirring speed is changed from 200 r / min to 500 r / min. Correspondingly, the product obtained in step (3) is a perovskite-type praseodymium-chromium-nickel-zinc composite oxide (Pr). 0.9 Cr 0.5 Ni 0.2 Zn 0.3 O 3-δ The product obtained in step (4) is a praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with metallic Ni nanoparticles loaded on its surface. 0.9 Cr 0.5 Zn 0.3 O 3-δ .

[0069] Example 16:

[0070] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct high-efficiency electrochemical oxidation of ammonia is disclosed. The specific preparation steps are basically the same as in Example 1, except that in step (2), the magnetic stirring temperature is changed from 80℃ to 90℃. Correspondingly, the product obtained in step (3) is a perovskite-type praseodymium-chromium-nickel-zinc composite oxide (Pr). 0.9 Cr 0.5 Ni 0.2 Zn 0.3 O 3-δThe product obtained in step (4) is a praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with metallic Ni nanoparticles loaded on its surface. 0.9 Cr 0.5 Zn 0.3 O 3-δ .

[0071] Example 17:

[0072] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct high-efficiency electrochemical oxidation of ammonia is disclosed. The specific preparation steps are basically the same as in Example 1, except that in step (3), the heating rate is changed from 2℃ / min to 5℃ / min. Correspondingly, the product obtained in step (3) is a perovskite-type praseodymium-chromium-nickel-zinc composite oxide (Pr). 0.9 Cr 0.5 Ni 0.2 Zn 0.3 O 3-δ The product obtained in step (4) is a praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with metallic Ni nanoparticles loaded on its surface. 0.9 Cr 0.5 Zn 0.3 O 3-δ .

[0073] Example 18:

[0074] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct high-efficiency electrochemical oxidation of ammonia is disclosed. The specific preparation steps are basically the same as in Example 1, except that in step (3), the calcination temperature is changed from 1100℃ to 1000℃. Correspondingly, the product obtained in step (3) is a perovskite-type praseodymium-chromium-nickel-zinc composite oxide (Pr). 0.9 Cr 0.5 Ni 0.2 Zn 0.3 O 3-δ The product obtained in step (4) is a praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with metallic Ni nanoparticles loaded on its surface. 0.9 Cr 0.5 Zn 0.3 O 3-δ .

[0075] Example 19:

[0076] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct high-efficiency electrochemical oxidation of ammonia is disclosed. The specific preparation steps are basically the same as in Example 1, except that in step (4), the volume ratio of H2:Ar is changed from 1:1 to 1:9. Correspondingly, the product obtained in step (3) is a perovskite-type praseodymium-chromium-nickel-zinc composite oxide (Pr). 0.9 Cr0.5 Ni 0.2 Zn 0.3 O 3-δ The product obtained in step (4) is a praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with metallic Ni nanoparticles loaded on its surface. 0.9 Cr 0.5 Zn 0.3 O 3-δ .

[0077] Example 20:

[0078] A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct high-efficiency electrochemical oxidation of ammonia is disclosed. The specific preparation steps are basically the same as in Example 1, except that in step (4), the reduction time is changed from 5 hours to 8 hours. Correspondingly, the product obtained in step (3) is a perovskite-type praseodymium-chromium-nickel-zinc composite oxide (Pr). 0.9 Cr 0.5 Ni 0.2 Zn 0.3 O 3-δ The product obtained in step (4) is a praseodymium-chromium-nickel-zinc based perovskite oxide (Ni / Pr) with metallic Ni nanoparticles loaded on its surface. 0.9 Cr 0.5 Zn 0.3 O 3-δ .

[0079] Comparative example:

[0080] A method for preparing a solid oxide fuel cell anode material includes the following steps:

[0081] Weigh 7.8302 g of praseodymium nitrate hexahydrate, 1.1632 g of nickel nitrate hexahydrate, and 4.0015 g of chromium nitrate nonahydrate, and dissolve them in 150 mL of deionized water to obtain solution A. Weigh citric acid monohydrate according to a molar ratio of 1.2:1 to the total amount of praseodymium, nickel, and chromium metal ions in solution A, and dissolve it in 50 mL of deionized water to obtain solution B. Add solution B to solution A and stir magnetically at 200 r / min for 60 minutes at room temperature to obtain a mixed solution. Stir the mixed solution magnetically at 200 r / min at 80 °C until the solvent is completely evaporated to obtain a transparent gel. Dry the transparent gel at 150 °C for 18 hours, then allow it to cool naturally to room temperature, and grind it to obtain a gel powder. The obtained gel powder was pre-calcined in air at a heating rate of 2℃ / min from room temperature to 600℃ for 2 hours, and then calcined in air at a heating rate of 2℃ / min from 600℃ to 1100℃ for 2 hours. It was then allowed to cool naturally to room temperature to obtain perovskite-type praseodymium-chromium-nickel composite oxide Pr. 0.9 Cr 0.8 Ni 0.2O 3-δ That is, solid oxide fuel cell anode material.

[0082] Anode slurry preparation:

[0083] Solid oxide fuel cell anode material was mixed with 8 mol% yttrium-stabilized zirconium oxide (8YSZ) at a mass ratio of 3:2, and ground in an agate mortar for 10 minutes until the color was uniform and there was no obvious particle texture, resulting in a mixed powder. Three drops of terpineol containing 4 wt% ethyl cellulose (CAS: 9004-57-3) were slowly added to the resulting mixed powder, and grinding continued for 20 minutes until the slurry was smooth and viscous, resulting in the anode slurry.

[0084] Product performance testing:

[0085] A single cell was fabricated using a 15mm diameter YSZ electrolyte sheet as the support. The specific fabrication process is as follows: First, the anode paste was screen-printed onto the electrolyte side (printing diameter 11mm, effective electrode area 0.95cm²). 2 Dry at 80℃; then print the LSM-60YSZ cathode paste onto the other side of the electrolyte in the same manner (printing diameter 5mm, effective electrode area 0.196cm²). 2 After drying at 80℃, the sample is calcined at 1100℃ in air for 2 hours, and then allowed to cool naturally to room temperature to obtain a single cell of anode paste | YSZ | cathode paste. After the single cell is prepared and before assembling the fuel cell, a thin layer of silver paste is uniformly screen-printed on the cathode side of the single cell as a current collector layer for collecting current.

[0086] Fuel cell assembly:

[0087] First, a silver wire and a nickel mesh were placed at the inlet of the test cell, with the anode side of the single cell facing the nickel mesh. Second, platinum paste was pre-coated at the contact point between the silver wire and the silver mesh on the cathode side to reduce contact resistance. Then, a silver mesh with an area similar to the silver paste was placed, and the silver wire was pressed onto the silver mesh to ensure a tight connection. Finally, the seams of the test cell were sealed with ceramic adhesive to ensure the airtightness of the device. During testing, pure ammonia at a flow rate of 50 mL / min was used as the fuel gas, static air as the oxidant, and pure hydrogen at a flow rate of 50 mL / min as the reference fuel. The performance of the fuel cell was tested using a dual-electrode method, with silver wires connecting the positive and negative electrodes of the electrochemical workstation (Zahner IM6).

[0088] Table 1. Current density and power density of fuel cells at 800°C with pure ammonia as fuel gas.

[0089]

[0090] The data analysis in Table 1 shows that: Pr 0.9 Cr0.8 Ni 0.2 O 3-δ Ni / Pr 0.9 Cr 0.7 Zn 0.1 O 3-δ Ni / Pr 0.9 Cr 0.6 Zn 0.2 O 3-δ Ni / Pr 0.9 Cr 0.5 Zn 0.3 O 3-δ andNi / Pr 0.9 Cr 0.4 Zn 0.4 O 3-δ The maximum output power densities of the fuel cells are 68, 106, 175, 292 and 210 mW / cm³, respectively. 2 Among them, Ni / Pr 0.9 Cr 0.5 Zn 0.3 O 3-δ The maximum output power density of a fuel cell is Pr 0.9 Cr 0.8 Ni 0.2 O 3-δ The 4.29-fold increase in performance compared to fuel cells indicates that the introduction of Zn components helps improve electrochemical performance.

[0091] Figure 1 a is Pr 0.9 Cr 0.8 Ni 0.2 O 3-δ Pr 0.9 Cr 0.7 Ni 0.2 Zn 0.1 O 3-δ Pr 0.9 Cr 0.6 Ni 0.2 Zn 0.2 O 3-δ Pr 0.9 Cr 0.5 Ni 0.2 Zn 0.3 O 3-δ (Example 1), Pr 0.9 Cr 0.4 Ni 0.2 Zn 0.4 O 3-δThe XRD pattern of the sample showed that its diffraction peaks were highly consistent with the standard spectrum of PrCrO3 perovskite (PDF#04-008-0112), corresponding to an orthorhombic perovskite structure with the Pnma space group; the diffraction peaks associated with ZnO or PrO2 increased with the ZnO content. 2+ The amount of incorporation is reflected in the catalyst. Figure 1 b is Pr 0.9 Cr 0.8 Ni 0.2 O 3-δ Ni / Pr 0.9 Cr 0.7 Zn 0.1 O 3-δ Ni / Pr 0.9 Cr 0.6 Zn 0.2 O 3-δ Ni / Pr 0.9 Cr 0.5 Zn 0.3 O 3-δ (Example 1), Ni / Pr 0.9 Cr 0.4 Zn 0.4 O 3-δ XRD patterns of Ni / Pr 0.9 Cr 0.5 Zn 0.3 O 3-δ Chinese Zn 2+ The maximum amount of solid solution enters the crystal lattice, resulting in a shift of the (121) crystal plane diffraction peak to a lower angle. Figure 2 The Py-IR results show that, with Zn 2+ As the doping concentration gradually increased to 0.3, the number of Lewis acid sites on the catalyst surface also continuously increased, and the solid-solidified Zn... 2+ It forms a zinc trap as a strong Lewis acid site. Figure 3 a is based on Pr 0.9 Cr 0.5 Ni 0.2 Zn 0.3 O 3-δ (Example 1) Performance of the fuel cell as the anode in pure ammonia fuel at 600~800°C; Figure 3 b showed Pr 0.9 Cr 0.5 Ni 0.2 Zn 0.3 O 3-δ (Example 1) Impedance spectra of a fuel cell as an anode in different atmospheres.

[0092] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a solid oxide fuel cell anode material based on zinc trap sites for direct, high-efficiency electrochemical oxidation of ammonia, characterized in that: Includes the following steps: (1) Synthesis of zinc-free precursor: Weigh praseodymium source, chromium source and nickel source, dissolve in deionized water, add citric acid monohydrate as complexing agent, stir and mix at room temperature, heat and stir until the solvent is completely evaporated to obtain transparent gel; dry and grind the transparent gel, and pre-calcine it at a programmed temperature in air atmosphere to obtain PCN precursor, i.e. zinc-free precursor; (2) Zinc source impregnation: Zinc source is dissolved in solvent to prepare impregnation solution, which is added dropwise to PCN precursor and heated and stirred until the solvent is completely evaporated to obtain Zn / PCN intermediate; (3) Phase formation in an oxidizing atmosphere: The Zn / PCN intermediate was calcined in an air atmosphere with a programmed temperature increase to obtain perovskite-type praseodymium-chromium-nickel-zinc composite oxide; (4) Reduction atmosphere treatment: The perovskite-type praseodymium-chromium-nickel-zinc composite oxide is reduced by programmed temperature rise under H2 / Ar mixed atmosphere to obtain praseodymium-chromium-nickel-zinc based perovskite oxide with metal Ni nanoparticles loaded on the surface, which is a solid oxide fuel cell anode material that realizes direct and efficient electrochemical oxidation of ammonia based on zinc trap sites.

2. The preparation method according to claim 1, characterized in that: Based on praseodymium, chromium, nickel, and zinc, the molar ratio of the praseodymium source, chromium source, nickel source, and zinc source satisfies the following relationship: praseodymium:chromium:nickel:zinc = 0.9:0.8-x:0.2:x, where 0 < x ≤ 0.4; the praseodymium source, chromium source, nickel source, and zinc source are metal salts, and the metal salts are any one or more of nitrates, acetates, and chlorides; the molar ratio of the monohydrated citric acid to the total amount of metal ions contained in the praseodymium source, chromium source, and nickel source is 1.2~2:

1.

3. The preparation method according to claim 1, characterized in that: In step (1), the drying conditions are: drying at 150~180℃ for 15~18 hours; the preheating conditions are: heating from room temperature to 500~600℃ at a heating rate of 2~5℃ / min for 2~5 hours.

4. The preparation method according to claim 1, characterized in that: In step (2), the solvent is deionized water or an aqueous ethanol solution; the heating and stirring conditions are: magnetic stirring at 200-500 r / min at 60-90℃.

5. The preparation method according to claim 1, characterized in that: In step (3), the conditions for the programmed temperature rise calcination are: heating from room temperature to 1000-1100℃ at a heating rate of 2-5℃ / min for 2-5 hours.

6. The preparation method according to claim 1, characterized in that: In step (4), the reducing atmosphere is a H2 / Ar mixed atmosphere; the conditions for the programmed temperature reduction are: heating from room temperature to 800℃ at a heating rate of 2~5℃ / min for 2~8 hours.

7. A solid oxide fuel cell anode material for achieving direct, efficient electrochemical oxidation of ammonia based on zinc trap sites, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 6.

8. The solid oxide fuel cell anode material according to claim 7, characterized in that: The solid oxide fuel cell anode material is a perovskite matrix with Zn dissolved in the matrix. 2+ It has strong Lewis acid zinc trap sites, and the matrix surface is uniformly dispersed with in-situ precipitated metallic Ni nanoparticles.

9. The application of the solid oxide fuel cell anode material as described in any one of claims 7 to 8 in a solid oxide fuel cell using pure ammonia as fuel.

10. A method for preparing a slurry of a solid oxide fuel cell anode material according to any one of claims 7-8, characterized in that: Solid oxide fuel cell anode material and YSZ are mixed at a mass ratio of 4~6:6~4, ground until uniform, and then terpineol containing 4wt% ethyl cellulose is added dropwise. The mixture is ground until smooth and viscous to obtain a slurry of solid oxide fuel cell anode material.

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