Regulating the d-p orbital hybridization in BaCo0.4Fe0.4Zr0.1Y0.1O3-s via Cu doping for high-performance solid oxide fuel cells cathode

The BaCo0.4Fe0.4Zr0.1Y0.1O3-delta (BCFZY) perovskite oxide is a highly promising cathode material for solid oxide fuel cells (SOFCs), mainly due to its exceptional three-phase conductivity at the elevated temperatures and remarkable oxygen reduction reaction (ORR) activity. Nevertheless, its limited electronic and ionic conductivities at relatively lower temperatures poses a significant challenge for its low-temperature applications. To address this issue, the Cu doping in the B-site of BCFZY is proposed. It is observed that Cu doping significantly enhances both the electronic conductivity and oxygen exchange kinetics, leading to a notable reduction in polarization resistance and a substantial improvement in ORR catalytic activity. Specifically, the Ni-YSZ anodesupported single cell equipped with BCFZYCu(4) as the cathode exhibits a remarkable power density of 1.30 W cm(-2) at 700 degrees C, which surpasses that of the single cell with BCFZY cathode by 51.16 %. An in-depth mechanism study has revealed that the enhanced performance is closely linked to the increased orbitals hybridization induced by Cu doping. This not only enlarges the covalency of the Co-O/Cu-O bonds but also shifts the metal 3d and O2p band center closer to the Fermi level, which significantly facilitates the oxygen adsorption, dissociation, and oxygen ion exchange processes of the BCFZYCu(4) cathode.