Electrochemical Preparation of Iridium Hydroxide Nanosheets with Ordered Honeycomb Structures for the Oxygen Evolution Reaction in Acid

Water electrolysis in acid using a proton exchange membrane electrolyzer has been considered as a promising technique for hydrogen production. Developing low-cost and high-performance OER catalysts is significant for scale-up application of this technique. In this work, we report a facile electrochemical approach to synthesize thin iridium hydroxide nanosheets (denoted as HxIrO3 NSs), which possess a unique honeycomb structure on the surface, as inherited from the parent α-Li2IrO3 material. The obtained HxIrO3 NSs show an average thickness of approximately 1.6 nm as measured using an atomic force microscope. Owing to the abundant exposed Ir active sites, the nanosheet catalyst demonstrates excellent OER activity with a low overpotential of 277 mV at 10 mA·cm–2 and maintaines a current density of 12.6 mA cm–2 (at a potential of 1.55 V vs RHE) for over 12 h in 0.5 M H2SO4 solution. In addition, fast proton dynamics is observed on catalyst–electrolyte interfaces, which is further correlated with the stable OER performance of HxIrO3 NSs. Overall, results of this work provide valuable information on the design and development of low-content iridium catalysts for achieving high mass activity and stability for water oxidation in acid.