当前位置: X-MOL 学术Energy Environ. Sci. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Understanding and mitigating A-site surface enrichment in Ba-containing perovskites: a combined computational and experimental study of BaFeO3
Energy & Environmental Science ( IF 32.5 ) Pub Date : 2022-09-06 , DOI: 10.1039/d2ee01813f
Jiapeng Liu, Jun Kyu Kim, Yuhao Wang, Hyunseung Kim, Alessio Belotti, Bonjae Koo, Zheng Wang, WooChul Jung, Francesco Ciucci

BaFeO3-Based perovskites are promising cathode materials for intermediate-temperature solid oxide fuel cells and protonic ceramic fuel cells due to their high electrocatalytic activity. However, during operation Ba has been observed to segregate towards the surface of these materials, deteriorating the activity. Herein, the surface of BaFeO3-based materials is studied using both density functional theory and strain-controlled epitaxial thin films. The results suggest that the surface Ba concentration can be controlled by tensile strain or by substituting Fe with a larger cation. Specifically, first-principles calculations suggest that the surface with low Ba content (i.e. (110)BaFeO), stabilizes when a biaxial tensile strain is applied, in agreement with the decreased surface Ba concentration observed in tensilely strained Ba0.95La0.05FeO3−δ thin films. As verified by simulations and experiments, substituting the Fe with the larger Zr cations also strains the material tensilely, thereby lowering Ba surface concentration. Further analysis suggests that stretching the Ba–O bond can strengthen the interaction between Ba and O and increase the energy required to form Ba vacancies in bulk, thereby reducing surface enrichment. Electrical conductivity relaxation and electrochemical impedance spectroscopy tests demonstrated that surface oxygen exchange kinetics is enhanced by introducing Zr into Ba0.95La0.05FeO3−δ. Zr-Substituted Ba0.95La0.05FeO3−δ is also shown to work effectively as a cathode for full solid oxide and proton ceramic fuel cells achieving high performance in the 600 to 850 °C range. This work explains how the surface composition of BaFeO3-based perovskites can be adjusted by lattice strain and cationic substitution, paving the way for the rational design of ceramic fuel cell cathode materials with enhanced performance.

中文翻译:

了解和减轻含钡钙钛矿中的 A 位表面富集:BaFeO3 的计算和实验相结合的研究

BaFeO 3基钙钛矿因其高电催化活性而成为中温固体氧化物燃料电池和质子陶瓷燃料电池的有前途的阴极材料。然而,在操作过程中,观察到 Ba 会向这些材料的表面偏析,从而降低活性。在此,使用密度泛函理论和应变控制的外延薄膜研究了 BaFeO 3基材料的表面。结果表明,表面Ba浓度可以通过拉伸应变或用较大的阳离子代替Fe来控制。具体来说,第一性原理计算表明,具有低 Ba 含量的表面((110)BaFeO) 在施加双轴拉伸应变时稳定,这与在拉伸应变 Ba 0.95 La 0.05 FeO 3- δ薄膜中观察到的表面 Ba 浓度降低一致。正如模拟和实验所证实的,用较大的 Zr 阳离子代替 Fe 也会使材料产生拉伸应变,从而降低 Ba 表面浓度。进一步的分析表明,拉伸 Ba-O 键可以加强 Ba 和 O 之间的相互作用,并增加形成块体 Ba 空位所需的能量,从而减少表面富集。电导弛豫和电化学阻抗谱测试表明,通过将 Zr 引入 Ba 0.95可增强表面氧交换动力学La 0.05 FeO 3− δ。Zr 取代的 Ba 0.95 La 0.05 FeO 3- δ也被证明可有效地用作全固体氧化物和质子陶瓷燃料电池的阴极,在 600 至 850 °C 范围内实现高性能。这项工作解释了如何通过晶格应变和阳离子取代来调节 BaFeO 3基钙钛矿的表面组成,为合理设计具有增强性能的陶瓷燃料电池正极材料铺平了道路。
更新日期:2022-09-06
down
wechat
bug