Optimizing Low-Temperature Ceramic Fuel Cells with CuFe2O4–CeO2 Heterostructures

Enhancing ionic conductivity and catalytic activity for slow oxygen reduction at lower operating temperatures could revolutionize the widespread adoption of low-temperature ceramic fuel cells (LT-CFCs; 400–550 °C). In this study, we introduce a semiconductor heterostructure composite consisting of a spinelike structure of CuFe2O4 (CFO) and CeO2, which is an efficient electrolyte membrane for solid oxide fuel cells. To improve fuel cell performance at suboptimal temperatures, we developed the CFO-CeO2 heterostructure composite. Our results demonstrate that a button-sized SOFC fueled by H2 and ambient air can deliver 750 mW/cm2 of power at 550 °C, potentially operating down to 400 °C. Furthermore, the CFO-CeO2 heterostructure composite exhibits higher oxygen vacancy and lower activation energy than individual CFO and CeO2 components, facilitating ion transit. Enhanced ionic conduction of the CFO-CeO2 heterostructure composite was thoroughly investigated using various transmission and spectroscopic techniques, including X-ray diffraction (XRD), photoelectron spectroscopy (PS), ultraviolet–visible (UV–vis), and impedance spectroscopy (IS). These findings underscore the effectiveness of the heterostructure approach for LT-SOFCs.