WOx nanowire supported ultra-fine Ir-IrOx nanocatalyst with compelling OER activity and durability

Ultra-fine iridium (Ir) nanocatalyst is successfully dispersed and stabilized on sub-stoichiometric tungsten oxide nanowires (WOxNW) forming an active and stable OER catalyst. With its abundant amount of exposed active surfaces, the WOxNW supported Ir catalyst shows a high mass activity of 812 A/gIr at 1.55 V vs RHE. This value is three times higher than Ir-black and 30 times higher than Ir supported on antimony-doped tin oxide. The Ir@WOxNW possesses much satisfactory stability, showing a loss of only 40 % compared with the nearly 100 % loss of Ir-black after 1,000 accelerated durability testing cycles. Non-destructive depth profile by synchrotronbased XPS and density functional calculations unambiguously reveal the strong catalyst-support interaction between the WOxNW and the supported Ir catalyst. Due to the inhibited oxidation, the OER active core-shell-like structure of the Ir-IrO2 is well-maintained on the WOxNW supports under OER testing conditions. The developed catalyst shows high potential to significantly reduce Ir usage for practical water electrolysis.