Enhanced Iridium Mass Activity of 6H-Phase, Ir-Based Perovskite with Nonprecious Incorporation for Acidic Oxygen Evolution Electrocatalysis.

One of the key objectives in PEM electrolysis technology is to reduce iridium loading and to improve iridium mass activity at the side of oxygen evolution electrocatalysis. 6H-phase, Ir-based perovskite (6H-SrIrO3) is known to be a promising alternative to the IrO2 catalyst, and developing effective strategies to further enhance its catalytic performance is needed. Here we present that a significant enhancement in electrocatalytic activity for the oxygen evolution reaction of 6H-SrIrO3 can be achieved by cobalt incorporation. A suitable amount of cobalt dopants results in a decreased formation temperature of 6H-SrIrO3 from 700 to 500 °C and thereby a decreased thickness of platelike particles for the material. Besides the morphological effect, the cobalt incorporation also increases the coverage of surface hydroxyl groups, regulates the Ir-O bond covalency, and modulates the oxygen p-band center of the material. This synergistic optimization of the morphological, surface, and electronic structures makes the cobalt-doped 6H-SrIrO3 catalyst give a 3-fold increase in iridium mass activity for oxygen evolution reaction in comparison with the undoped 6H-SrIrO3 under acidic conditions.