Self-supported nanostructured iridium-based networks as highly active electrocatalysts for oxygen evolution in acidic media

Abstract

Due to the slow kinetics of the oxygen evolution reaction (OER), high precious metal loadings are currently required at the anode of proton exchange membrane (PEM) electrolyzers. In this work, we present a novel, scalable and efficient method for the fabrication of high surface area iridium-based electrocatalysts. Using alternating sputtering of iridium and cobalt, followed by selective leaching, we produce a self-supported and highly active OER electrocatalysts for acidic environments. Nanostructured IrO_x-networks present a bulk-like behaviour, with a site-specific activity similar to that of extended polycrystalline IrO_x surfaces. Moreover, in terms of mass activity, the IrO_x-networks are among the most active Ir-based catalysts reported, presenting a mass activity enhancement by a factor of eight over commercial Ir-black nanoparticles. These novel self-supported Ir-based networks are very stable, which, combined with their enhanced mass activity, makes them promising anode catalysts for PEM electrolyzers.