SrIrO3 modified with laminar Sr2IrO4 as a robust bifunctional electrocatalyst for overall water splitting in acidic media

Abstract

Strontium iridate perovskites are attractive electrocatalysts for acidic water oxidation, but suffer from serious Srleaching during catalysis, which causes surface rearrangements that damage long-term applications. Herein, 6H phase SrIrO3 modified with laminar Sr2IrO4 (SrIrO) have been developed. Unlike the previous extreme chemical state changes of Ir, SrIrO maintained relatively stable surface Ir states during electrocatalysis. The layered nature of Sr2IrO4 enables the interlaminar Sr easily extracted from the crystal while remaining the in-plane IrO6 octahedral framework, thereby stabilizing the Ir state. The SrIrO displays extremely low overpotential of 245 mV for OER and 18.2 mV for HER at 10 mA cm-2, and outstanding catalytic stability. For acidic water splitting, SrIrO requires only 1.50 V to achieve 10 mA cm-2, surpassing most reported electrocatalysts. This work offers a new route for alleviating the surface rearrangements of perovskites, and exploring efficient and stable electrocalysts for hydrogen production via electrochemical water electrolysis.