Catalyst-Support Interactions in Zr2ON2-Supported IrOx Electrocatalysts to Break the Trade-Off Relationship Between the Activity and Stability in the Acidic Oxygen Evolution Reaction

Abstract

The development of highly active and durable Ir-based electrocatalysts for the acidic oxygen evolution reaction (OER) is challenging because of the corrosive anodic conditions. Herein, IrOx/Zr2ON2 electrocatalyst is demonstrated, employing Zr2ON2 as a support material, to overcome the trade-off between the activity and stability in the OER. Zr2ON2 is selected due to its excellent electrical conductivity and chemical stability, and the fact that it induces strong interactions with IrOx catalysts. As a result, IrOx/Zr2ON2 electrocatalysts exhibit outstanding OER performances, reaching an overpotential of 255 mV at 10 mA cm(-2) and a mass activity of 849 mA mg(Ir)(-1) at 1.55 V (vs the reversible hydrogen electrode). The activity of IrOx/Zr2ON2 is maintained at 10 mA cm(-2) for 5 h, while in contrast, IrOx/ZrN and an unsupported IrOx catalyst undergo drastic degradation. Combined experimental X-ray analyses and theoretical interpretations reveal that the reduced oxidation state of Ir and the extended Ir-O bond distance in IrOx/Zr2ON2 effectively increase the activity and stability of IrOx by altering reaction pathway from a conventional adsorbate evolution mechanism to a lattice oxygen-participating mechanism. These results demonstrate that it is possible to effectively reduce the Ir content in OER catalysts through interface engineering without sacrificing the catalytic performance.