Highly efficient air electrodes are a key component of reversible fuel cells for energy storage and conversion; however, the development of efficient electrodes that are stable against water vapor remains a grand challenge. Here we report an air–electrode, composed of double perovskite material PrBa_0.8Ca_0.2Co₂O_5+δ (PBCC) backbone coated with nanoparticles (NPs) of BaCoO_3−δ (BCO), that exhibits remarkable electrocatalytic activity for oxygen reduction reaction (ORR) while maintaining excellent tolerance to water vapor. When tested in a symmetrical cell exposed to wet air with 3 vol% H₂O at 750 °C, the electrode shows an area specific resistance of ∼0.03 Ω cm² in an extended period of time. The performance enhancement is attributed mainly to the electrocatalytic activity of the BCO NPs dispersed on the surface of the porous PBCC electrode. Moreover, in situ Raman spectroscopy is used to probe reaction intermediates (e.g., oxygen species) on electrode surfaces, as the electrochemical properties of the electrodes are characterized under the same conditions. The direct correlation between surface chemistry and electrochemical behavior of an electrode is vital to gaining insight into the mechanisms of the electrocatalytic processes in fuel cells and electrolysers.

中文翻译：

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通过水诱导表面改性促进钙钛矿双电极上的氧还原反应

高效的空气电极是可逆燃料电池进行能量存储和转换的关键组件。然而，开发对水蒸气稳定的高效电极仍然是一个巨大的挑战。在这里，我们报告了一种空气电极，它由双重钙钛矿材料PrBa _0.8 Ca _0.2 Co ₂ O _{5+ δ}（PBCC）骨架组成，包覆有BaCoO _{3− δ}（BCO）的纳米颗粒（NPs），具有出色的电催化还原氧的活性反应（ORR），同时保持出色的水蒸气耐受性。在750°C的暴露于3 vol％H ₂ O的湿空气中的对称电池中测试时，该电极的面积比电阻约为0.03Ωcm²在延长的时间内。性能的提高主要归因于分散在多孔PBCC电极表面的BCO NP的电催化活性。此外，原位拉曼光谱法被用来探测电极表面上的反应中间体（例如，氧物种），因为在相同条件下表征了电极的电化学性质。电极的表面化学性质与电化学行为之间的直接关联对于深入了解燃料电池和电解槽中电催化过程的机制至关重要。