Oxygen evolution reaction electrocatalysis on SrIrO3 grown using molecular beam epitaxy

Abstract

Electrochemical generation of oxygen via the oxygen evolution reaction (OER) is a key enabling step for many air-breathing electrochemical energy storage devices. IrO₂ (Ir⁴⁺: 5d⁵) ranks among the most active known OER catalysts. However, it is unclear how the environment of the Ir⁴⁺ oxygen-coordination octahedra affects the OER electrocatalysis. Herein, we present the OER kinetics on a single-crystal, epitaxial SrIrO₃(100)_p perovskite oxide synthesized using molecular-beam epitaxy on a DyScO₃(110) substrate. We find that by switching the host structure of the Ir⁴⁺ oxygen-coordination octahedra from corner- and edge-sharing rutile (IrO₂) to purely corner-sharing perovskite (SrIrO₃), the OER activity increases by more than an order of magnitude. We explain our finding with the correlated, semimetal electronic structure of SrIrO₃; our density functional theory calculations reveal that the adsorption energetics on SrIrO₃ depends sensitively on the electron–electron interaction, whereas for IrO₂, it depends rather weakly. This finding suggests the importance of correlations on the OER and the design of future transition metal oxide electrocatalysts.