Fe-doped SrCoO3 perovskite oxides as efficient bifunctional electrocatalysts for overall water splitting

Perovskite oxides have emerged as promising electrocatalysts for water splitting due to their structural flexibility and tunable electronic properties. In this work, a series of SrCo 1-x Fe x O 3 (SCF, x = 0.2, 0.4, 0.6, and 0.8) perovskite oxides were synthesized and investigated as bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1 M KOH. X-ray diffraction and Rietveld refinement reveal that SCF0.2, SCF0.4, and SCF0.6 crystallize predominantly in a cubic perovskite structure, whereas excessive Fe incorporation in SCF0.8 induces symmetry lowering to a tetragonal phase. X-ray photoelectron spectroscopy confirms mixed-valence Co 2+ /Co 3+ and Fe 2+ /Fe 3+ redox states, which play a crucial role in enhancing catalytic activity. Electrochemical studies demonstrate that SCF0.6 exhibits better HER performance, delivering a low overpotential of 379 mV at 10 mA cm −2 , and a Tafel slope of 58.62 mV dec −1 . For OER, SCF0.4 delivers better activity, achieving an overpotential of 400 mV at 10 mA cm −2 , a small Tafel slope of 54.18 mV dec −1 . The composition-dependent activity arises from optimized structural symmetry, lattice distortion, and interfacial charge transfer. This study highlights rational Fe substitution as an effective strategy for designing efficient and durable perovskite electrocatalysts for alkaline water electrolysis.