Perovskite
oxides, as oxygen sorbents, exhibit excellent potential
in thermochemical redox applications such as chemical looping air
separation (CLAS), resulting from their excellent redox properties
and high tunability. The structural and compositional flexibility
of perovskites, while making these mixed oxides highly versatile,
also poses challenges for their design and optimization. Moreover,
the elevated operating temperature and dynamic oxygen partial pressure
swings during redox processes add additional complications for oxygen
sorbent design. From a fundamental standpoint, finding simple yet
effective descriptors for the effect of cation substitutions on oxygen
sorbents’ redox and oxygen transport properties are of significant
importance for rational optimization of perovskite-based oxygen sorbents.
In the present study, a series of A/B-site-doped SrFeO3‑δ perovskites are investigated using density functional theory (DFT)
+ U simulations. From these simulations, an effective
electronic structural descriptor, the net electronic charge (Δe) of oxygen anions, is extracted based on its excellent
correlations with vacancy formation energy, experimentally derived
oxygen capacity, and oxygen vacancy migration barrier. These findings
provide an effective tool to correlate the oxygen sorbents’
redox performances with a simple yet physically meaningful descriptor
for rational design and optimization of perovskites in the context
of CLAS.