IrO2-graphene hybrid as an active oxygen evolution catalyst for water electrolysis

In the present work, graphene supported IrO₂ catalyst (IrO₂/RGO) has been synthesized by hydrothermal method in ethanol/water mixture solvent. X-ray diffraction (XRD) and transmission electron microscopy (TEM) tests reveal that IrO₂ is uniformly supported on RGO surface with ultrafine IrO₂ nanoparticles (ca. 1.7 nm). Linear sweep voltammetry (LSV) tests indicate that the catalytic activity of IrO₂/RGO hybrid towards oxygen evolution reaction (OER) is 2.3 times that of commercial IrO₂. The superior OER activity of IrO₂/RGO hybrid is attributed to the enhanced surface area and the improved electrical conductivity of IrO₂ due to the introduction of graphene support. Lifetime tests demonstrate that IrO₂/RGO hybrid has unexpectedly high OER durability. It also displays an excellent performance in long-time water electrolysis. This may be interpreted in terms of the dispersion retention of IrO₂ nanoparticles on RGO surface, which is caused by the interaction between IrO₂ and Π-electrons of RGO.