An ultrathin two-dimensional iridium-based perovskite oxide electrocatalyst with highly efficient {001} facets for acidic water oxidation

The oxygen evolution reaction (OER) is an electrochemical bottleneck half-reaction in some important energy conversion systems (e.g., water splitting), which is traditionally mediated by iridium oxides in acidic environment. Perovskite-structured Ir-containing oxides (e.g., SrIrO₃) are a family of striking electrocatalysts due to their high specific activity, but this excellent quality is difficultly transferred to a nano-electrocatalyst with large active surface and good structural stability. Here, we present a synthesis method that produces a 2D ultrathin {001}-faceted SrIrO₃ perovskite (2D-SIO) with a thickness of ∼5 nm and high surface area (57.6 m² g⁻¹). We show that 2D-SIO can serve as a highly active and stable electrocatalytic nanomaterial for OER under acidic conditions. This perovskite nanomaterial produces 10 mA cm⁻² current density at a low overpotential (η, 243 mV), and maintains its catalytic activity after 5000 continuous cyclic measurements. Besides ultrathin structure and large surface area, the exposed {001} facets are found to be the most crucial and unique structural factor for achieving high catalytic activity and structural stability. Our joint experimental and theoretical results demonstrate that these advantageous microstructural features of 2D-SIO endow it with a strong capability to generate the key O* intermediates, and thereby facilitate O–O bond formation and the OER.