Highly active and stable OER electrocatalysts derived from SrMIrO for proton exchange membrane water electrolyzers.

Proton exchange membrane water electrolysis is a promising technology to produce green hydrogen from renewables, as it can efficiently achieve high current densities. Lowering iridium amount in oxygen evolution reaction electrocatalysts is critical for achieving cost-effective production of green hydrogen. In this work, we develop catalysts from Ir double perovskites. SrCaIrO achieves 10 mA cm at only 1.48 V. The surface of the perovskite reconstructs when immersed in an acidic electrolyte and during the first catalytic cycles, resulting in a stable surface conformed by short-range order edge-sharing IrO octahedra arranged in an open structure responsible for the high performance. A proton exchange membrane water electrolysis cell is developed with SrCaIrO as anode and low Ir loading (0.4 mg cm). The cell achieves 2.40 V at 6 A cm (overload) and no loss in performance at a constant 2 A cm (nominal load). Thus, reducing Ir use without compromising efficiency and lifetime.