Abstract The oxidation and reduction of metal oxides and their interaction with the environment play a critical role in their use for energy storage and conversion applications. The formation of surface adsorbates and their impact on oxide electronic structure can be challenging to probe experimentally, particularly for thin films which enable the study of epitaxial strain but have low surface areas. Here we present a detailed study using ambient pressure X-ray photoelectron spectroscopy of the reduction and oxidation of strained SrFeO3-δ, induced by changes in temperature, oxygen partial pressure, and water vapor exposure. We find that in comparison to the oxidized lattice, application of tensile strain promotes the formation of oxygen vacancies at the surface, facilitating the subsequent incorporation of oxygen into the lattice in an oxygen environment. While tensile strain does promote the formation of hydroxyls from water dissociation, the kinetics of this process appear more sluggish than on less-strained surfaces, likely due to a competitive surface interaction with oxygen or bulk absorption of hydroxyl species. These findings relating strain, oxygen vacancies, and surface reactivity yield important insight into the surface functionality of oxides for energy conversion and storage applications.

中文翻译：

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应变对 SrFeO3-δ 氧化、还原和水离解的影响：来自环境压力 X 射线光电子能谱的见解

摘要 金属氧化物的氧化和还原及其与环境的相互作用在其用于能量存储和转换应用中起着至关重要的作用。表面吸附物的形成及其对氧化物电子结构的影响在实验上可能具有挑战性，特别是对于能够研究外延应变但具有低表面积的薄膜。在这里，我们使用环境压力 X 射线光电子能谱对应变 SrFeO3-δ 的还原和氧化进行了详细研究，该过程由温度、氧分压和水蒸气暴露的变化引起。我们发现，与氧化晶格相比，拉伸应变的应用促进了表面氧空位的形成，促进随后氧在氧环境中结合到晶格中。虽然拉伸应变确实促进了水解离形成羟基，但该过程的动力学似乎比在应变较小的表面上更缓慢，这可能是由于与氧的竞争性表面相互作用或羟基物质的大量吸收。这些与应变、氧空位和表面反应性相关的发现产生了对用于能量转换和存储应用的氧化物表面功能的重要见解。