A New Family of Perovskite Catalysts for Oxygen-Evolution Reaction in Alkaline Media: BaNiO₃ and BaNi_0.83O_2.5

Establishment of a sustainable energy society has been strong driving force to develop cost-effective and highly active catalysts for energy conversion and storage devices such as metal-air batteries and electrochemical water splitting systems. This is because the oxygen evolution reaction (OER), a vital reaction for the operation, is substantially sluggish even with precious metals-based catalysts. Here, we show for the first time that a hexagonal perovskite, BaNiO₃, can be a highly functional catalyst for OER in alkaline media. We demonstrate that the BaNiO₃ performs OER activity at least an order of magnitude higher than an IrO₂ catalyst. Using integrated density functional theory calculations and experimental validations, we unveil that the underlying mechanism originates from structural transformation from BaNiO₃ to BaNi_0.83O_2.5 (Ba₆Ni₅O₁₅) over the OER cycling process.