Deconvoluting Reversible and Irreversible Degradation Phenomena in OER Catalyst Coated Membranes Using a Modified RDE Technique

Abstract

The suitability of the Thin-Film RDE (TF-RDE) technique to rigorously evaluate stability measurements for the oxygen evolution reaction (OER) was recently questioned. The main issue was the inability to deconvolute bubble blockage of catalytic active sites from catalyst dissolution using the TF-RDE technique. It is also possible that the low-loading of TF-RDE OER catalysts exacerbates the effect of bubble blockage. In this work, the modified rotating disk electrode (MRDE) is used with commercial catalyst coated membranes (CCMs) to evaluate catalyst stability. The MRDE may be better suited for stability measurements, since the CCM samples used can better avoid experimental artifacts and can explore much higher current densities than a TF-RDE. Thicker catalyst layers have good adhesion to the membrane, making experimental artifacts less pronounced in stability measurements. Three different stability protocols are used to study the effect of cycling, lower/upper potential limits, and regeneration. The protocol which induced the most irreversible degradation was the square-wave voltammetry (SWV) cycling between 0.05–2.0 VRHE. This irreversible degradation is likely the result of catalyst dissolution. The importance of differentiating between irreversible and reversible degradation is highlighted as a potential future standard for stability evaluation.