Engineering Metal-Metal Junctions from Layered Double Hydroxide Frameworks for High-Rate Solid Oxide Cells

Abstract

Heterogeneous catalysts comprising metal nanoparticles (NPs) on oxide supports are widely employed in high-temperature electrochemical devices such as solid oxide cells (SOCs). Unfortunately, these catalysts frequently exhibit structural instability at metal-oxide interfaces due to lattice mismatch, resulting in diminished catalytic activity and overall performance degradation over time. This work introduces an unprecedented approach of synthesizing intermetallic supports with metal-metal junctions by utilizing layered double hydroxide (LDH) structures. The LDH-derived framework undergoes controlled phase transitions, yielding an intermetallic structure decorated with exsolved Co─Fe alloy nanoparticles under reducing conditions, which would be the key for effectively mitigating the interfacial strain. This engineered electrode demonstrates exceptional electrocatalytic activity toward fuel oxidation reaction at high temperature regimes above 700°C. Furthermore, composite formation with oxygen ion conductive Gd0.1Ce0.9O2-δ (GDC) simultaneously augments electrochemical performance and structural stability, achieving a peak power density of 1.57 W cm−2 at 800°C under H2 fuel, while maintaining stable operation under SOC operations. This work hence presents an innovative strategy for designing structurally robust, efficient, and durable metal-metal junctions, thereby advancing the fields of high-temperature electrochemistry and catalysis.