Localized lattice strain in perovskite oxides for enhanced oxygen reduction reaction kinetics in solid oxide fuel cells

The cathode of a solid oxide fuel cell (SOFC) must exhibit both high activity and robust durability for effective utilization in electrochemical oxygen reduction reaction (ORR). To address this challenge, we present a novel strain engineering strategy that involves the creation of nanoscale local lattice strain microdomains to further enhance the ORR kinetics. Specifically, Ga cations are introduced into some of the B-sites of the perovskite Pr_0.4Sr_0.6Fe_0.5Co_0.5O_3-δ (PSFC). Benefiting from local lattice strain engineering, the bulk oxygen migration coefficient of the locally strained PSFC sample is significantly enhanced, reaching twice that of the pure PSFC sample at 650 °C. Moreover, the polarization impedance of PSFC (0.102 Ω·cm²) is more than twice that of Pr_0.4Sr_0.6Fe_0.4Co_0.5Ga_0.1O_3-δ (PSFCG, 0.043 Ω·cm²) at 800 °C. Microscopic structural analyses and computational calculations indicate that the optimized electronic structure of the rich micro-strain catalyst reduces the bond energy of adjacent B-O bonds and the oxygen transport barrier. This work demonstrates a practical local lattice micro-strain engineering strategy and provides a new approach for improving the performance of ORR electrocatalysts.