Topochemical Synthesis of Iridium Oxide Nanoribbons with Monoclinic Phase for Highly Efficient Electrocatalytic Oxygen Evolution

Abstract Metastable metallene oxides with ribbon morphology possess promising applications, however, are largely restricted by their limited synthesis method. Here a new metallene oxide, monoclinic phase iridium oxide nanoribbon (IrO2NR), with the space group of C2/m is successfully obtained, which is totally different from that of the stable tetragonal phase (P42/mnm). The molten-alkali mechanochemical method provides a unique platform to achieve this layered nanoribbon structure via the topochemical conversion evolving from the monoclinic phase K0.25IrO2 (I2/m (12) precursor. The formation mechanism of IrO2NR is clearly illuminated with its further conversion to IrO2 nanosheet with trigonal phase. When applied in the acidic oxygen evolution reaction (OER), the intrinsic catalytic activity of IrO2NR is much higher than that of the tetragonal phase IrO2 due to the low d band center of Ir in such a new monoclinic phase structure as confirmed by density functional theory calculation.