Exceptionally active iridium evolved from a pseudo-cubic perovskite for oxygen evolution in acid

Abstract

Exploring robust catalysts for water oxidation in acidic electrolyte is challenging due to the limited material choice. Iridium (Ir) is the only active element with a high resistance to the acid corrosion during water electrolysis. However, Ir is rare, and its large-scale application could only be possible if the intrinsic activity of Ir could be greatly enhanced. Here, a pseudo-cubic SrCo_0.9Ir_0.1O_3-δ perovskite, containing corner-shared IrO6 octahedrons, is designed. The Ir in the SrCo_0.9Ir_0.1O_3-δ catalyst shows an extremely high intrinsic activity as reflected from its high turnover frequency, which is more than two orders of magnitude higher than that of IrO₂. During the electrochemical cycling, a surface reconstruction, with Sr and Co leaching, over SrCo_0.9Ir_0.1O_3-δ occurs. Such reconstructed surface region, likely contains a high amount of structural domains with corner-shared and under-coordinated IrO_x octahedrons, is responsible for the observed high activity.

While water splitting could provide a green means to store energy, there are few materials that can sustain high water oxidation half-reaction rates in acidic electrolytes. Here, authors design a perovskite oxide that generates high performance under-coordinated iridium sites during electrocatalysis.