IrO2/LiLa2IrO6 as a robust electrocatalyst for the oxygen evolution reaction in acidic media

Abstract

Recently reported non-noble metal–iridium mixed oxides not only exhibit excellent activity for the oxygen evolution reaction in acidic media, but also reduce the cost. However, most of them fail to overcome the poor stability of amorphous iridium oxide formed on the surface after leaching of the non-noble metal. Herein, we describe a LiLa₂IrO₆ electrocatalyst with a thin IrO₂ shell (IrO₂/LiLa₂IrO₆) that achieves a win–win situation for both activity and stability under harsh acidic conditions. The synthesized IrO₂/LiLa₂IrO₆ catalyst exhibits outstanding activity for the OER in 0.1 M HClO₄ electrolyte, and needs a low overpotential of 278 mV to deliver the benchmark of 10 mA cm⁻², superior to commercially available IrO₂ and most recently reported catalysts. More significantly, IrO₂/LiLa₂IrO₆ shows enhanced electrochemical stability with only 160 mV increase in potential after testing over 13 h, in contrast to commercial IrO₂ that almost lost its activity toward the OER in 7 h. This demonstrates that the high performance for catalyzing the OER is ascribed to the in situ formed IrO_x highly active layer by surface reconstruction as well as the strong interaction between IrO_x and bulk LiLa₂IrO₆.