Iridium-Doped Monoclinic Zirconia as a Catalyst for the Oxygen Evolution Reaction

New acid-stable catalysts that reduce reliance on iridium (Ir) for the oxygen evolution reaction (OER) could pave the way for efficient energy conversion and storage. Using DFT this work investigates Ir-dopings of the monoclinic $$ ($$) surface as an Ir-lean OER catalyst. It is found that these Ir-doped surfaces are likely to segregate into their constituent oxide phases, $$ and $$. The OER activity is limited due to under binding of the OER intermediates on pure $$ and overbinding on the Ir-doped surface, both leading to high overpotentials. Water adsorption on the surface layer stabilizes all surfaces, with a more pronounced stabilization observed for the Ir-doped systems. This adsorption significantly impacts the activity for the nondoped surface, as leaving a surface site unoccupied creates a high energy state in the band gap, making the surface highly reactive. A similar situation is found for an Ir-doped surface, contrasted by the formation of lower energy states.