Engineering oxygen vacancies on dendrite-like IrO2 for the oxygen evolution reaction in acidic solution

Here we report IrO2 with dendrite-like nanostructures (DLNs) as a catalyst for the oxygen evolution reaction (OER) in acidic solution. The IrO2 DLNs are prepared by the molten salt method and have self-standing three dimensional structures. IrO2 with DLNs has a high mass activity determined to be 19-fold that of commercial IrO2. Combining a wide array of ex situ characterization methods, we demonstrate that the sublayer Ir cations and lattice O participate in the OER. The Ir corrosion and O/OH- adsorption during the OER can lead to IrO2 surface reconstruction, from a compressed one to a stretched one.