Efficient oxygen evolution electrocatalysis in acid by a perovskite with face-sharing IrO₆ octahedral dimers

The widespread use of proton exchange membrane water electrolysis requires the development of more efficient electrocatalysts containing reduced amounts of expensive iridium for the oxygen evolution reaction (OER). Here we present the identification of 6H-phase SrIrO₃ perovskite (6H-SrIrO₃) as a highly active electrocatalyst with good structural and catalytic stability for OER in acid. 6H-SrIrO₃ contains 27.1 wt% less iridium than IrO₂, but its iridium mass activity is about 7 times higher than IrO₂, a benchmark electrocatalyst for the acidic OER. 6H-SrIrO₃ is the most active catalytic material for OER among the iridium-based oxides reported recently, based on its highest iridium mass activity. Theoretical calculations indicate that the existence of face-sharing octahedral dimers is mainly responsible for the superior activity of 6H-SrIrO₃ thanks to the weakened surface Ir-O binding that facilitates the potential-determining step involved in the OER (i.e., O* + H₂O → HOO* + H⁺ + e_¯).