Temperature tunability in Sr1−xCaxFeO3−δ for reversible oxygen storage: a computational and experimental study,Journal of Materials Chemistry A

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Temperature tunability in Sr1−xCaxFeO3−δ for reversible oxygen storage: a computational and experimental study
Journal of Materials Chemistry A ( IF 10.7 ) Pub Date : 2020/01/14 , DOI: 10.1039/c9ta09307a
Eric J. Popczun _{1,

2,

2,

3,

4} , De Nyago Tafen _{1,

2,

3,

4,

5} , Sittichai Natesakhawat _{1,

2,

3,

6,

7} , Chris M. Marin _{1,

2,

2,

3,

4} , Thuy-Duong Nguyen-Phan _{1,

2,

2,

3,

4} , Yunyun Zhou _{1,

2,

3} , Dominic Alfonso _{1,

2,

3} , Jonathan W. Lekse _{1,

2,

3}

Affiliation

Reversible oxygen absorption/desorption in earth-abundant materials is fundamental towards many advanced technologies that require a pure oxygen stream including oxy-combustion via chemical looping and oxygen-blown coal gasification. The Sr_1−xCa_xFeO₃ system is one of many perovskite oxides that have drawn attention given the large quantities of oxygen it can produce during mild cycling conditions. In this work, we employ hybrid functional based DFT calculations to establish the oxygen vacancy formation energy, ΔE_f,vac, as an effective parameter for describing the Sr_1−xCa_xFeO₃ system. We validate these calculations experimentally using XPS, O₂-TPD, TGA, and synchrotron pXRD. In all cases, we find that increasing calcium content lowers both the oxygen desorption temperature and preferred operating temperature for the system. Importantly, we are able to experimentally show the structural and functional cyclability of these materials, achieving rapidly accessible maximum oxygen storage capacities of 1.51–2.41 wt% for temperatures of 400–700 °C.

中文翻译：

Sr1-xCaxFeO3-δ中可逆氧气存储的温度可调性：计算和实验研究

丰富的地球材料中可逆的氧气吸收/解吸是许多先进技术的基础，这些先进技术要求纯净的氧气流，包括通过化学回路进行氧气燃烧和吹氧煤气化。Sr _{1- x} Ca _x FeO ₃系统是许多钙钛矿氧化物之一，由于在温和的循环条件下会产生大量氧气，因此引起了人们的关注。在这项工作中，我们采用基于混合函数的DFT计算来建立氧空位形成能ΔE _f，vac，作为描述Sr _{1- x} Ca _x FeO ₃的有效参数。系统。我们使用XPS，O ₂ -TPD，TGA和同步加速器pXRD通过实验验证了这些计算。在所有情况下，我们都发现增加钙的含量会降低系统的氧气脱附温度和优选操作温度。重要的是，我们能够通过实验证明这些材料的结构和功能可循环性，在400–700°C的温度下，可快速达到1.51–2.41 wt％的最大储氧量。

更新日期：2020-02-10

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