Oxygen Storage Property of Sr₃Fe₂O_7−δ

Abstract

Sr₃Fe₂O_7−δ with layered perovskite structure shows an excellent oxygen storage performance and has significant potential in the fields of oxygen separators/sensors and the purification of polluted materials such as automobile exhaust gas. This review introduces effects of Pd loading on Sr₃Fe₂O_7−δ and of doping with other transition metals (Mn, Co, Ni) into the Fe sites of Sr₃Fe₂O_7−δ. Pd loading dramatically improves oxygen release rate under H2 atmosphere, because Pd species enhances the adsorption and dissociation of H₂. Mn doping of Sr₃Fe₂O_7−δ also increases the oxygen release rate of Sr₃Fe₂O_7−δ. Although the local structures around the transition-metal species in Sr₃(Fe_0.8Co_0.2)₂O_7−δ and Sr₃(Fe_0.8Ni_0.2)₂O_7−δ are largely disordered by the release of lattice oxygen, the cation ordering of the as-synthesized Sr₃(Fe_0.8Mn_0.2)₂O_7−δ was maintained by doping with Mn, even in the reduced state. These results indicate that the oxygen release rate under H2 atmosphere largely contributes to the surface reaction and structural changes in the perovskite structures upon release of lattice oxygen.