Strain?Induced Orbital Contributions to Oxygen Electrocatalysis in Transition?Metal Perovskites

Epitaxial strain has been shown to produce dramatic changes the orbital structure in transition metal perovskite oxides and, turn, rate of oxygen electrocatalysis therein. Here, epitaxial is used investigate relationship between surface electronic and prototypical fuel cell cathode systems. Combining high-temperature electrical-conductivity-relaxation studies synchrotron-based X-ray absorption spectroscopy La0.5Sr0.5CoO3 La0.8Sr0.2Co0.2Fe0.8O3 thin films under varying degrees reveals a strong correlation catalysis rates. In both systems, biaxial tensile simultaneously exhibit fastest reaction kinetics lowest electron occupation dz2 orbitals. These results are discussed context broader chemical trends descriptors proposed for oxides.