High Cationic Dispersity Boosted Oxygen Reduction Reactivity in Multi-Element Doped Perovskites
Wenhuai Li (Nanjing Tech University)
Mengran Li (TU Delft - ChemE/Materials for Energy Conversion and Storage)
Yanan Guo (Nanjing Tech University)
Zhiwei Hu (Max Planck Institute for Chemical Physics of Solids)
Chuan Zhou (Nanjing Tech University)
Helen E.A. Brand (Australian Nuclear Science and Technology Organisation)
Vanessa K. Peterson (Australian Nuclear Science and Technology Organisation)
Chih Wen Pao (Australian Nuclear Science and Technology Organisation)
Chien Te Chen (National Synchrotron Radiation Research Center, Hsinchu)
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Abstract
Oxygen-ion conducting perovskite oxides are important functional materials for solid oxide fuel cells and oxygen-permeable membranes operating at high temperatures (>500 °C). Co-doped perovskites have recently shown their potential to boost oxygen-related kinetics, but challenges remain in understanding the underlying mechanisms. This study unveils the local cation arrangement as a new key factor controlling oxygen kinetics in perovskite oxides. By single- and co-doping Nb5+ and Ta5+ into SrCoO3-δ, dominant factors affecting oxygen kinetics, such as lattice geometry, cobalt states, and oxygen vacancies, which are confirmed by neutron and synchrotron X-ray diffraction as well as high-temperature X-ray absorption spectroscopy, are controlled. The combined experimental and theoretical study unveils that co-doping likely leads to higher cation dispersion at the B-site compared to single-doping. Consequently, a high-entropy configuration enhances oxygen ion migration in the lattice, translating to improved oxygen reduction activity.