Electrodeposited IrO2/Ti electrodes as durable and cost-effective anodes in high-temperature polymer-membrane-electrolyte water electrolyzers.

Graphical abstract Highlights • A thin IrO 2 film is uniformly coated on porous Ti mesh via anodic electrodeposition. • The IrO 2 film is an efficient catalyst layer for the oxygen evolution reaction. • A high current density (0.97 A cm−2 at 1.6 V) at 0.4 mg cm−2 is produced at 120 °C. • The electrodeposited film physically blocks exposure of the Ti diffusion layer. • The IrO 2 film protects against Ti corrosion and improves cell durability at 120 °C. Abstract In this study, IrO 2 -coated Ti mesh (e-IrO 2 /Ti) is proposed to be an efficient and durable oxygen electrode for high-temperature polymer-membrane-electrolyte water electrolyzers (HT-PEMWEs). A thin IrO 2 film of submicron thickness was uniformly coated onto a porous Ti mesh substrate by anodic electrodeposition. The electrodeposited IrO 2 film plays the dual role of a catalyst layer for the oxygen evolution reaction (OER), and a corrosion-protection layer that prevents oxidation of the inner Ti. The e-IrO 2 /Ti exhibited high performance (0.97 A cm−2 at 1.6 V) despite a low IrO 2 loading (0.4 mg cm−2) in single-cell tests conducted at 120 °C, which is comparable to that of conventional electrodes with greater catalyst loadings (0.8–5 mg cm−2). Furthermore, corrosion polarization tests reveal that the IrO 2 coating physically blocks exposure of the Ti diffusion layer, thereby reducing Ti corrosion by 82% in 0.5 M H 2 SO 4 at 25 °C. The low degradation rate (1.5 mA cm‐2 h−1 (0.11% h−1)) obtained in aging experiments at 120 °C and 1.72 V (voltage efficiency of 85%) confirms the excellent stability of this electrode. [ABSTRACT FROM AUTHOR]