Sr掺杂LaFeO3钙钛矿型氧载体的氧迁移性能,Physical Chemistry Chemical Physics

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Sr掺杂LaFeO3钙钛矿型氧载体的氧迁移性能
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2023-03-15 , DOI: 10.1039/d2cp05129j
Yuan Feng ₁ , Hanyu Jin ₁ , Shuai Wang ₁

Affiliation

化学式为ABO ₃的钙钛矿型金属氧化物在化学链过程中表现出优异的氧化还原反应性能，其中A通常是碱土金属，B是过渡金属。氧传递性能对氧载体的性能起着重要作用。在这项研究中，研究了LaFeO ₃（ABO ₃型）钙钛矿表面和主体之间氧空位形成能和氧迁移势垒的差异，通过密度泛函理论 (DFT)。考虑了 Sr 掺杂对 A 位的影响。结果表明，表面 Fe 和 O 之间相互作用的共价性高于本体，A 位上的 Sr 掺杂增强了这种共价性，导致较低的氧空位形成能。氧迁移屏障也随着离表面的距离不同而不同。周围晶格原子与其在较深层晶体中的原始位置的较小偏差导致较高的氧迁移能量。同时，Sr掺杂增加了晶格常数，导致更大的迁移空间，从而降低了迁移势垒。此外，Sr 掺杂可以削弱近表面和本体之间氧迁移势垒的差异。

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Oxygen migration performance of LaFeO3 perovskite-type oxygen carriers with Sr doping

A perovskite-type metal oxide with the formula of ABO₃ exhibits excellent redox reaction properties for the chemical looping process, where A is usually an alkaline earth metal and B is a transition metal. The oxygen transfer property plays an important role in the performance of oxygen carriers. In this study, the difference in oxygen vacancy formation energy and oxygen migration barrier between the surface and the bulk in the LaFeO₃ (ABO₃ type) perovskite is investigated via density functional theory (DFT). The effect of Sr doping on the A-site is considered. The results show that the covalency of the interaction between Fe and O at the surface is higher than that in the bulk, and the Sr doping on the A-site enhances this covalency, leading to a lower oxygen vacancy formation energy. The oxygen migration barrier is also different with the distance from the surface. A smaller deviation of the surrounding lattice atoms from their original place in the crystal at a deeper layer leads to a higher oxygen migration energy. Meanwhile, Sr doping increases the lattice constant, leading to larger migration space thus lowering the migration barrier. In addition, Sr doping can weaken the difference in the oxygen migration barrier between near the surface and in the bulk.

更新日期：2023-03-15

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