New multi-functional catalyst coated membrane structure for improved water electrolysis

Abstract

The state of proton exchange membrane water electrolysis (PEMWE) technology is largely dependent on conventional iridium catalyst layers with a lack of material and structural alternatives. For the first time, a catalyst coated membrane (CCM) structure is demonstrated to improve iridium catalyst utilization and decrease hydrogen crossover simultaneously. The anode catalyst layer is composed of an electrolessly-deposited Pt layer (<130 μg cm−2) at the membrane surface with a lower loading of iridium oxide catalyst (∼1.2 mg cm−2 IrOx) sprayed on the platinized membrane with variable thicknesses. These samples were subjected to rigorous catalyst characterization and crossover evaluation via a benchtop modified rotating disk electrode (MRDE) and an electrolysis cell (50 cm2), respectively. The MRDE results show that the CCM structure with the electroless Pt layer decreases the potential by as much as 100–200 mV at 1 A cm−2. At the unit cell level, the performance enhancement was in the range of 400–600 mV at 2 A cm−2. The parasitic hydrogen crossover current density is reduced by about 40 % when comparing this novel structure approach to baseline CCMs. This multi-functional CCM structure can potentially reshape the standards for PEM and for alkaline electrolyte membrane water electrolysis.