Achieving Strong Coherency for a Composite Electrode via One-Pot Method with Enhanced Electrochemical Performance in Reversible Solid Oxide Cells

The oxygen electrode with a fast oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and sufficient durability plays a pivotal role in reversible solid oxide cells (RSOCs). Here, we demonstrate a NdBa_0.5Ca_0.5Co_1.5Fe_0.5O_5+δ@Gd_0.1Ce_0.9O_2−δ (NBCCF@GDC) composite oxygen electrode via a one-pot method for exhibiting strong coherency, which result in boosting the electrochemical performance of RSOCs. The NBCCF@GDC electrode yields a very low polarization resistance (0.106 Ω-cm² at 800 °C), high electrolysis current density (1.45 A cm^–2 with 70 vol % absolute humidity at 1.3 V), and high power density (∼1.3 W cm^–2 at 800 °C) and shows excellent reversibility and stability. Notably, strong coherency in these NBCCF@GDC composite materials was successfully revealed by HT-XRD, XPS, STEM, and EELS. The phase contiguity and interfacial coherence between NBCCF and GDC increase the Co oxidation state and the number of active sites, which enhanced the electrocatalytic activity for perovskites. Overall, this work demonstrates a highly desirable strategy for the production of functionalized electrodes for next-generation reversible solid oxide cells.