Effects of B‐site doping and stoichiometry on strontium ferrate Sr _0.85 Ce _0.15 Fe _x Co _y O ₃ perovskites as electrocatalysts

Abstract SrFeO 3 ‐based oxides are multi‐functional ceramics belonging to the ABO 3 ‐type perovskite family, where iron is interestingly present at the B‐site as Fe 4+ and partially reducible to Fe 3+ by doping strategies to tailor the physical–chemical properties. When doped, fine‐tuned SrFeO 3 is exploitable in novel energy production systems, for example, electrocatalysts in intermediate temperature solid oxide fuel cells (IT‐SOFCs). This work aimed to evaluate how the B‐site composition and stoichiometry affect the functional properties of SrFeO 3 ‐based materials when A‐site doping with cerium is fixed at 15 mol%. Hence, powdered samples were prepared by solution combustion synthesis, modulating the Fe/Co ratio or the B‐site stoichiometry (Fe + Co). From an in‐depth characterization, it was found that both B‐site nonstoichiometry and Fe/Co ratio influenced structure, redox properties, and electrochemical behavior. Still, nonstoichiometry played a major role in improving oxygen adsorption capacity and mobility, also thanks to the contribution of the segregated phases (CeO 2 , Sr 3 Fe 2 O 7− δ ) generated by the induced B‐site unbalancing. The nonstoichiometric sample reached the highest oxygen reduction capability at the IT‐SOFC operating temperature (600°C) and the lowest activation energy (0.65 eV), whereas the cobalt‐rich sample showed poorer performance as an oxygen electrode. These results encourage further research on tunable cobalt‐poor and nonstoichiometric perovskites in energy‐related devices.