Shortening Accelerated Stress Tests: An Identical Charge Approach for Oxygen Evolution Reaction Electrocatalysts

Proton exchange membrane water electrolysis (PEMWE) is expected to play a major role in hydrogen production due to its suitability for dynamic response and load flexibility, which are relevant for operation with electricity from fluctuating renewables. A central problem is however the loading reduction of scarce and expensive iridium, which is needed to catalyze the sluggish oxygen evolution reaction (OER) on the anode while maintaining activity and stability. To accelerate improvements on the anode catalyst side, it is central to evaluate electrocatalyst stability fast and to assess its suitability for dynamic operation. In this study, we evaluate the possibility of reducing the time for stability screening of a commercial iridium oxide catalyst by using a constant charge approach, which is desirable to enable high throughput screening. The approach is inspired by the relationship between OER and the dissolution mechanism. For this, a scanning flow cell with online inductively coupled plasma mass spectrometry (SFC-ICP-MS) is used to measure time-resolved iridium dissolution. Further, the impact of dynamic stress protocols on degradation is assessed. For this, a static current hold is fragmented into square wave protocols using shorter start–stop cycles while maintaining the cumulative time under current and total applied charge. Our results show that an acceleration of testing can be achieved while the total dissolution per charge remains similar. The choice of pulsing parameters critically affected catalyst dissolution and inconsistencies with full cell degradation trends in literature revealed the need to consider pseudocapacitive current contributions.