In-situ reconstructed hollow iridium-cobalt oxide nanosphere for boosting electrocatalytic oxygen evolution in acid

Iridium oxide (IrO x )-based materials perform high efficiency and durability for oxygen evolution reaction (OER) in acidic environment. Developing highly efficient OER electrocatalysts with low Ir-loading in acid is still a great challenge. Herein, we fabricated a hollow IrCoO x nanosphere via in-situ electrochemistry reconstruction strategy. The developed hollow Ir 0.16 Co 0.84 O x electrocatalyst with low Ir-loading (51.91 μg cm −2 ) exhibits 71-fold and 42-fold improvement in OER mass activity and TOF value compared with commercial IrO 2 (1032.16 vs 14.44 A g Ir −1 , 0.754 vs 0.018 s −1 ) in 0.1M HClO 4 , respectively. Combining with the analysis of the IrCoO x structure, the electrochemical performance reveals that the superior activity ascribes to the favorable hollow structure, the abundant crystalline/amorphous heterostructure in the IrO x -enriched shell and the atomic heterointerfaces between Co and Ir oxides, which increase the electrochemical active area, accelerate the OER kinetics and lower the charge transfer resistance (2.8 Ω cm 2 ). This work is anticipated to aid the design of novel low Ir-loading electrocatalysts with outstanding catalytic activity for water splitting in acidic environments.