Designing active and stable Ir-based catalysts for the acidic oxygen evolution reaction

The widespread application of polymer electrolyte membrane water electrolyzers (PEMWEs) remains a tough challenge to date, as they rely on the use of highly scarce iridium (Ir) with insufficient catalytic performance for the oxygen evolution reaction (OER). Therefore, exploring the degradation and activation mechanism of Ir-based catalysts during the OER and searching for highly efficient Ir-based catalysts are essential to achieve large-scale hydrogen production with PEMWEs. This minireview briefly describes the adsorbate evolution mechanism and lattice oxygen oxidation mechanism for Ir-based catalysts to complete the OER process. Then, the valence change of Ir during the OER is discussed to illustrate the origin of the favorable stability of Ir-based catalysts. After that, different modification strategies for IrO₂, such as elemental doping, surface engineering, atom utilization enhancing, and support engineering, are summarized in the hopes of finding some commonalities for improving performance. Finally, the perspectives for the development of Ir-based OER catalysts in PEMWEs are presented.

Keywords: Polymer electrolyte membrane water electrolyzers; Oxygen evolution reaction; Iridium catalysts; Degradation mechanism; Hydrogen production.