Localized lattice strain in perovskite oxides for enhanced oxygen reduction reaction kinetics in solid oxide fuel cells
Abstract
The cathode of a solid oxide fuel cell (SOFC) must exhibit both high activity and robust durability for effective utilization in electrochemical oxygen reduction reactions (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 Pr0.4Sr0.6Fe0.5Co0.5O3-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 Pr0.4Sr0.6Fe0.4Co0.5Ga0.1O3-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.