Reverse atomic capture strategy to enhance catalytic activity and suppress Sr segregation for low-temperature solid oxide fuel cell cathodes

Developing efficient and stable electrocatalysts for the oxygen reduction reaction (ORR) is pivotal for advancing electrochemical energy conversion devices such as solid oxide fuel cells (SOFCs). However, limited active sites and element segregation on the ORR electrocatalyst surfaces often lead to slow kinetics and poor stability. A reverse atomic capture strategy has been developed to enhance lattice oxygen redox activity and suppress Sr segregation in Pr_0.4Sr_0.6CoO_3-δ (PSC) perovskite oxide. The unfavourable Sr cations segregated from PSC are successfully captured by WO₃, leading to the abundant Sr/O vacancies at the surface and subsurface levels. PSC with surface Sr/O vacancies (V-PSC) exhibits superior ORR activity, achieving a peak power density of 0.356 W cm⁻² at 450 °C, which represents a 106.8 % performance compared to bare PSC. The introduced Sr/O vacancies adjust the O 2p band and reduce the energy barrier for the rate-determining steps of ORR, significantly improving the reaction kinetics. Furthermore, the introduction of surface vacancies enhances the segregation energy to bulk Sr sites, with the material maintaining excellent stability over nearly 260 hours of durability testing, showing only a 1.82 % decay rate. This advancement opens up broad possibilities for modifying stable oxide surfaces to improve surface defect control and offers a scalable approach for atomic trapping strategies.