The oxygen uncoupling mechanism in CaFeO3-δ: A combined DFT and kinetic validation

Rational design of perovskite oxygen carriers requires understanding of oxygen uncoupling kinetics, yet the relative contributions of surface reactions versus bulk diffusion remain poorly quantified. Here we establish a combined computational-experimental framework for CaFeO 3- δ . DFT maps the oxygen uncoupling pathway—from vacancy diffusing to surface O 2 uncoupling—with barriers of 0.50 eV (bulk) and 2.24 eV (surface). Non-isothermal thermogravimetry and an Avrami model solved via convex optimization enable robust extraction of intrinsic kinetic parameters. The macroscopic E α (1.14 eV) is substantially higher than the bulk diffusion barrier (0.50 eV) yet much lower than the ideal surface O 2 uncoupling barrier (2.24 eV), indicating that surface uncoupling remains the rate-determining step but via defect-mediated pathways on real surfaces. This underscores the potential of surface engineering for performance optimization and provides a basis for tailoring CaFeO 3- δ in chemical looping hydrogen production.