摘要
The optimization of the catalyst layer architecture is critical for proton exchange membrane water electrolysis (PEMWE), particularly in reducing the loading of iridium anode catalysts. Under conditions of ultra-low iridium loading, ion and mass transport are severely impeded, which hampers the kinetic performance of oxygen evolution reaction (OER) catalysts. In this study, we propose a bilayer anode design for PEMWE composed of an ultra-thin active catalyst layer on top of a supporting base layer. The position of the active layer is critical to the performance of the anode, showing significant benefits in reducing kinetic and ohmic overpotential only when placed adjacent to the porous transport layer (PTL). This resulted in a 30 % increase in output current density and improved durability when having just 0.03 mg cm(-2) iridium black (Ir-black) on top of the 0.26 mg cm(-2) iridium oxide (Ir-oxide). Furthermore, this design can use OER-inactive platinum black as the base layer for the same amount of Ir-black to achieve better performance than a single Ir-oxide catalyst layer with ten times mass loading. Although serious platinum loss resulted in poor durability, the bilayer anode design opens a new path for realizing ultra-low iridium-loaded PEMWE for cost effective green hydrogen production.