Mixed ionic and electronic conducting (MIEC) perovskite oxides (ABO₃) have a substantial role in carbon-neutral clean energy conversion and storage technologies. Owing to their favorable catalytic properties, high ionic and electronic conductivity, and chemical and redox stability, MIEC perovskite oxides are promising electrode materials in multiple applications, such as solid oxide fuel/electrolysis cells, oxygen transport membranes, metal–air batteries, electrochemical sensors, and electrocatalysts for water splitting. Here, taking (La_0.8Sr_0.2)_0.95Cr_0.5Fe_0.5O_3−δ (LSCrF8255) as a model MIEC perovskite oxide, we demonstrate that the oxygen mass transport properties are significantly enhanced under a humid reducing water vapor environment (pO₂ < 1 mbar, pH₂O = 30 mbar) by up to 4 orders of magnitude compared to those measured under dry (pO₂ = 200 mbar) and wet (pO₂ = 200 mbar, pH₂O = 30 mbar) oxygen atmospheres. A 0.8 eV decrease in the activation energy for oxygen bulk diffusion was also found under water vapor, and a decrease in activation energy of 0.7 eV for water surface exchange compared to oxygen surface exchange was found. The mechanisms underpinning these enhancements were explored. Furthermore, LSCrF8255 has also exhibited a consistent surface composition evolution regarding Sr segregation and phase separation and an excellent bulk stability under both oxidizing and reducing environments at elevated temperatures.

中文翻译：

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在减湿环境下混合导电钙钛矿氧化物的氧传输性能显着增强

混合离子和电子导电 (MIEC) 钙钛矿氧化物 (ABO ₃ ) 在碳中性清洁能源转换和存储技术中发挥着重要作用。由于其良好的催化性能、高离子和电子电导率以及化学和氧化还原稳定性，MIEC 钙钛矿氧化物在多种应用中是有前景的电极材料，例如固体氧化物燃料/电解电池、氧传输膜、金属-空气电池、电化学传感器和用于水分解的电催化剂。这里，取 (La _0.8 Sr _0.2 ) _0.95 Cr _0.5 Fe _0.5 O _3-δ(LSCrF8255) 作为模型 MIEC 钙钛矿氧化物，我们证明了在潮湿的还原水蒸气环境 (pO ₂ < 1 mbar，pH ₂ O = 30 mbar)下，氧传质性能显着增强了多达 4 个数量级。到那些在干 (pO ₂ = 200 mbar) 和湿 (pO ₂ = 200 mbar, pH ₂O = 30 mbar) 氧气气氛。在水蒸气下也发现氧体扩散的活化能降低 0.8 eV，与氧表面交换相比，水表面交换的活化能降低 0.7 eV。探索了支持这些增强功能的机制。此外，LSCrF8255 在 Sr 偏析和相分离方面也表现出一致的表面成分演变，以及在高温氧化和还原环境下的出色体积稳定性。