Suppression of Mn Dissolution During Proton Exchange Membrane Water Electrolysis by Ir Doping of MnO2 Anodes

Abstract In proton exchange membrane water electrolysis (PEMWE), iridium (Ir) is typically used for the anode catalyst due to its high activity and stability. However, the limited availability of Ir presents a significant challenge for meeting future hydrogen demands, and technologies to reduce Ir usage are therefore urgently required. Here, we investigated the dissolution behavior of Ir-doped MnO 2 (Ir-MnO 2 ) to aid the development of alternatives to conventional Ir-based catalysts. UV-vis analysis revealed that Ir doping suppressed the dissolution of MnO 2 to MnO 4 - during water electrolysis. Further examination of the relationship between Ir-MnO 2 composition and Mn dissolution revealed that an Ir/Mn molar ratio of 0.024 gave the lowest rate of Mn dissolution (2.5 μg cm -2 day -1 in 0.1 M HClO 4 at 200 mA/cm 2 ). Ir-MnO 2 with an Ir/Mn molar ratio of 0.024 (0.1 mg Ir /cm 2 ) exhibited a degradation rate of only 7 μV/h over 4,000 h at 2 A/cm 2 in a PEMWE test. These results suggest that suppression of Mn dissolution is associated with the long-term durability of Ir-MnO 2 anodes.