Supported IrO 2 Nanocatalyst with Multilayered Structure for Proton Exchange Membrane Water Electrolysis.

The design of a low-iridium-loading anode catalyst layer with high activity and durability is a key challenge for a proton exchange membrane water electrolyzer (PEMWE). Here, the synthesis of a novel supported IrO 2 nanocatalyst with a tri-layered structure, dubbed IrO 2 @TaO x @TaB that is composed of ultrasmall IrO 2 nanoparticles anchored on amorphous TaO x overlayer of TaB nanorods is reported. The composite electrocatalyst shows great activity and stability toward the oxygen evolution reaction (OER) in acid, thanks to its dual-interface structural feature. The electronic interaction in IrO 2 /TaO x interface can regulate the coverage of surface hydroxyl groups, the Ir 3+ / Ir 4+ ratio, and the redox peak potential of IrO 2 for enhancing OER activity, while the dense TaO x overlayer can prevent further oxidation of TaB substrate and stabilize the IrO 2 catalytic layers for improving structural stability during OER. The IrO 2 @TaO x @TaB can be used to fabricate an anode catalyst layer of PEMWE with an iridium-loading as low as 0.26 mg cm -2 . The low-iridium-loading PEMWE delivers high current densities at low cell voltages (e.g., 3.9 A cm -2 @2.0 V), and gives excellent activity retention for more than 1500 h at 2.0 A cm -2 current density.