Heterovalent Cu²⁺/Mo⁶⁺ bimetallic doping strategy for enhanced ORR kinetics and Cr tolerance in solid oxide fuel cell cathodes

Solid oxide fuel cell (SOFC) cathodes face critical challenges including activity-stability trade-offs and chromium poisoning. This work proposes a heterovalent Cu/Mo bimetallic co-doping strategy for Pr_0.4Sr_0.6Co_0.5Fe_0.5O_3−δ-based perovskites to synergistically optimize oxygen reduction reaction (ORR) kinetics and structural stability. The low-valent Cu doping enhances the surface oxygen exchange rate by reducing oxygen vacancy formation energy, while the high-valent Mo doping strengthens the Mo[sbnd]O bonds and reduces the oxygen migration energy barrier at adjacent sites. The synergistic effect results in a 78 % reduction in electrochemical impedance, outperforming the single-doped systems. Under chromium (Cr) poisoning, the degradation rate of PSCFCM cathode is only 0.07 % h⁻¹, demonstrating enhanced chemical stability. This bimetallic co-doping strategy offers a versatile approach for designing SOFC cathodes with enhanced activity and durability.