Iridium-cobalt oxide synthesized via surfactant-assisted Adams fusion for efficient oxygen evolution in acidic and alkaline media

A series of iridium-cobalt (Ir-Co) oxide catalysts were synthesized using a modified surfactant-assisted Adam’s fusion method and evaluated for the oxygen evolution reaction (OER) in both acidic and alkaline media. The effect of varying the Ir/Co ratio was systematically studied and compared with commercial Ir black and pure IrO 2 samples. The actual elemental ratios were quantified using X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDS). Among the synthesized samples, the Ir 6 Co 4 catalyst exhibited the best performance in acidic media, achieving an iR -corrected overpotential of 292 mV. In alkaline conditions, it demonstrated comparable activity to Ir black, with an iR -corrected overpotential of 263 mV. XPS and electron energy loss spectroscopy analyses revealed that increasing Co content led to a higher fraction of metallic Ir (Ir 0 ) in the catalyst. In addition, the role of Ir 3+ in enhancing OER activity was explored. A strong correlation was observed between higher Ir 3+ content and improved OER performance in acidic conditions. • Novel Ir-Co catalyst design is employed by surfactant-assisted Adams fusion method. • The nanoparticles mainly consist of iridium embedded within a cobalt oxide matrix. • Ir-Co catalysts show higher mass activity than pure Ir samples in acidic media. • Increasing Co content more than 40% reduces catalytic stability. • Ir 3+ species are crucial in enhancing OER performance in acidic environments.