Metallic nanoparticles structured perovskite oxides prepared by the in situ exsolution method are widely utilized as alternative anodes for solid oxide fuel cells. In this work, Sr_xFe_1.3Ni_0.2Mo_0.5O_6−δ (SFNMx, x = 1.90, 1.95, 2.00, and 2.05) materials are prepared to construct Ni–Fe alloy nanoparticles structured SFNMx anodes. It is found that the microstructure as well as electrochemical activity of SFNMx anodes can be successfully manipulated by altering A-site Sr non-stoichiometry. Moreover, the electrochemical performance of the symmetrical cells with SFNMx electrodes demonstrates that A-site Sr deficiency can effectively accelerate the exsolution of Ni–Fe alloy nanoparticles from the parent oxides, reasonably providing more active sites for the hydrogen oxidation reaction and effectively lowering the electrode polarization resistance to 1.04 Ω cm² with decreasing Sr content to 1.95, which is in good agreement with the results predicted by the regular-solution model. In addition, the distribution of relaxation times analysis results indicate that H₂ adsorption/dissociation/ionization, which can be strongly accelerated by in situ exsolved Ni–Fe alloy nanoparticles, is the predominant rate-limiting step. It is concluded that A-site non-stoichiometry in perovskites can greatly facilitate the exsolution of metallic nanoparticles, and enable effectively enhanced electrochemical activity. Our findings can guide the development of nano-architectures of A_1−xBO₃ materials for other energy conversion and storage devices.

中文翻译：

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了解钙钛矿中的A位非化学计量：促进金属纳米颗粒的析出和固体氧化物燃料电池中的氢氧化反应

通过原位提取方法制备的金属纳米颗粒结构的钙钛矿氧化物被广泛用作固体氧化物燃料电池的替代阳极。在这项工作中，准备了Sr _x Fe _1.3 Ni _0.2 Mo _0.5 O _{6- δ}（SFNM x，x = 1.90，1.95，2.00 ，和2.05）材料来构造Ni-Fe合金纳米颗粒结构的SFNM x阳极。发现通过改变A-位Sr非化学计量比可以成功地控制SFNM x阳极的微观结构和电化学活性。此外，SFNM对称电池的电化学性能x电极表明，A部位Sr的缺乏可有效加速Ni-Fe合金纳米粒子从母体氧化物的析出，合理地为氢氧化反应提供更多的活性部位，并随着Sr的降低将电极的极化电阻有效降低至1.04Ωcm ²。满足1.95，这与常规解决方案模型预测的结果非常吻合。另外，弛豫时间的分布分析结果表明，H _2的吸附/离解/电离作用可以被原位加速。Ni-Fe合金纳米颗粒的固溶是主要的限速步骤。结论是钙钛矿中的A位非化学计量可以极大地促进金属纳米颗粒的溶出，并能够有效地增强电化学活性。我们的发现可以指导用于其他能量转换和存储设备的A ₁ - _x BO ₃材料的纳米结构的开发。