Catalyst‐Support Interactions in Zr₂ON₂‐Supported IrO_x 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, IrO x /Zr 2 ON 2 electrocatalyst is demonstrated, employing Zr 2 ON 2 as a support material, to overcome the trade‐off between the activity and stability in the OER. Zr 2 ON 2 is selected due to its excellent electrical conductivity and chemical stability, and the fact that it induces strong interactions with IrO x catalysts. As a result, IrO x /Zr 2 ON 2 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 IrO x /Zr 2 ON 2 is maintained at 10 mA cm −2 for 5 h, while in contrast, IrO x /ZrN and an unsupported IrO x 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 IrO x /Zr 2 ON 2 effectively increase the activity and stability of IrO x 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.