In Situ Engineering of a Cobalt-free Perovskite Air Electrode Enabling Efficient Reversible Oxygen Reduction/evolution Reactions

作者：Hu, Tong; Zhu, Feng; Xia, Jiaojiao; He, Fan; Du, Zhiwei; Zhou, Yucun; Liu, Ying; Wang, Haobing; Chen, Yu^*

来源：Advanced Functional Materials, 2023, 33(43).

DOI：10.1002/adfm.202305567

• air electrodes
• cobalt-free perovskites
• oxygen reduction
• evolution reaction
• reversible protonic ceramic electrochemical cells

Reversible protonic ceramic electrochemical cells (R-PCECs) have received increasing focus for their good capability of converting and storing energy. However, the widely used cobalt-based air electrodes are less thermomechanically compatible with the electrolyte and lack stability, which largely limits the development of R-PCECs. Herein, a cobalt-free perovskite with a nominal composition of PrBa0.8Ca0.2Fe1.8Ce0.2O6 & delta; (PBCFC) is reported, which is in-situ engineered to a (Ba, Ce) deficient-PBCFC phase, a BaCeO3, and a CeO2 phase under typical operating conditions, delivering a low area-specific resistance of 0.10 & omega;cm(2) at 700 C-o. The generated BaCeO3 and CeO2 particles increase the conduction/transfer of protons and oxygen ions, thus providing extra active sites for the oxygen reactions. When utilized as an air electrode on a single cell, it achieves encouraging performance at 700 & DEG;C: a peak power density of 1.78 Wcm(-2) and a current density of 5.00 Acm(-2) at 1.3 V in the dual mode of the fuel cell (FC) and electrolysis (EL) mode with reasonable Faradaic efficiencies. In addition, the cells exhibit favorable operational durability of 65 h (FC mode), 95 h (EL mode), and promising cycling stability of 200 h.

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