Tetragonal ZrO2 supported low-iridium catalyst activating oxygen spillover stabilized lattice oxygen for proton exchange membrane water electrolysis

Abstract

Mediating the trade-off between activity and durability at a low Ir loading is challenging for the acidic oxygen evolution reaction (OER) in proton exchange membrane (PEM) water electrolysis. Herein, we construct an efficient and stable low-iridium loaded anode electrocatalyst supported on porous tetragonal zirconium oxide (IrO_x/t-ZrO₂) that exhibits a high mass activity of 1464.6 A g_Ir⁻¹ at 1.6 V and can operate stably at 10 mA cm⁻² for more than 1000 h in acidic electrolyte without any degradation. Structural characterization studies, electrochemical analyses and theoretical calculations reveal active lattice oxygen redox over a supported IrO_x nanocluster, stabilized by oxygen spillover from the t-ZrO₂ substrate during the OER process. This oxygen spillover engaged lattice oxygen oxidation pathway can not only boast OER kinetics via avoiding scaling relationships between oxygen intermediates, but also prevent the collapse of IrO_x by the prompt recovery of migrated oxygen species. A PEM electrolyzer using IrO_x/t-ZrO₂ as the anode material, with a significantly low Ir loading of 0.1 mg_Ir cm⁻², demonstrates 3.10 A cm⁻² at only 1.9 V, and low activity decay (6.25 μV h⁻¹) during a 1600 h test at 1 A cm⁻².