The role of A-site cation size mismatch in tune the catalytic activity and durability of double perovskite oxides

Abstract The double perovskite oxides are intriguing catalysts for energy conversion/storage and chemical sensor systems. The cation surface segregation is a stubborn issue that restricts their application. Herein, A-site cation size mismatch (MA) was proposed for the first time as a critical intrinsic parameter for controlling the surface chemistry and electrochemical performance of the double perovskite catalyst. The studies in PrBa1-xCaxCoCuO5+δ revealed that lowering MA can relieve lattice distortion, enlarge PrOδ layer space, maintain surface chemistry, and significantly improve catalytic activity and durability of the double perovskite. Specifically, as MA decrease from 26.1 to 18.1%, the output peak power density of PrBa1-xCaxCoCuO5+δ-based single-cells increase from 1.47 to 2.04 W cm-2 (800 °C) while the output current density retentions rise from 82.2 to 94.7% after 100 hours (700 °C and 0.7 V). This guides the design of robust double perovskite catalysts in solid oxide cells, metal-air batteries, photocatalysis, and oxygen sensors.