Catalyst-Support Interactions in Zr₂ON₂-Supported IrO_x Electrocatalysts for Enhnaced Activity and Stability in the Acidic Oxygen Evolution Reaction.

Overcoming the challenge of developing highly active and durable Ir-based electrocatalysts for the acidic oxygen evolution reaction (OER) is difficult due to the corrosive conditions experienced during anodic processes. In this study, we present the utilization of IrO_x/Zr₂ON₂ electrocatalysts, which employ Zr₂ON₂ as a support material, to address the trade-off between activity and stability in the OER. Zr₂ON₂ was chosen for its exceptional electrical conductivity and chemical stability, as well as its ability to form strong interactions with the IrO_x catalysts. As a result, the IrO_x/Zr₂ON₂ electrocatalysts demonstrated remarkable OER performance, achieving an overpotential of 255 mV at 10 mA/cm² and a mass activity of 849 mA/mg_Ir at 1.55 V (versus the reversible hydrogen electrode). The activity of IrO_x/Zr₂ON₂ was sustained at 10 mA/cm² for 5 hours, while the unsupported IrOx catalyst and IrOx/ZrN underwent significant degradation. Through a combination of experimental X-ray analyses and theoretical interpretations, it was discovered that the reduced oxidation state of Ir and the extended Ir-O bond distance in IrO_x/Zr₂ON₂ effectively enhanced the activity and stability of IrO_x by modifying the reaction pathway from a conventional adsorbate evolution mechanism to a mechanism involving participation of lattice oxygen. These findings demonstrate that it is possible to significantly reduce the Ir content in OER catalysts through interface engineering without compromising their catalytic performance.