Understanding how structural and compositional features influence the Oxygen Reduction Reaction (ORR) and Oxygen Evolution Reaction (OER) in oxygen electrocatalysis is crucial for the rational design of efficient catalysts. The O p-band center, obtained from density functional theory (DFT) calculations, serves as a predictive electronic descriptor linking the composition and structure of the oxide catalyst to ORR and OER activity. Ruddlesden–Popper oxides Srn+1FenO3n+1 (1 < n < ∞) provide a versatile platform for tuning this descriptor. Here, we systematically evaluate the effects of dimensionality, Fe substitution, and oxygen nonstoichiometry in the Srn+1Fen(1–x)MnxO3n+1−δ series (n = 1, 2, ∞; M = 3d-metal; x = 1/8; δ = 0, 1/8). Both increasing slab thickness (n = 1 → ∞) and Fe substitution with more electronegative transition metal elements enhance metal–oxygen hybridization, shifting the O p-band center toward the Fermi level by up to 0.2 and 0.45 eV, respectively, whereas 12% oxygen deficiency shifts it downward by up to 0.45 eV. Across the series, the combined effects of composition and structure span a ∼0.7 eV range in the O p-band center, implying only modest intrinsic variations in ORR/OER activity, often surpassed by extrinsic factors such as morphology and microstructure.
Gómez-Toledo et al. (Sat,) studied this question.