The kinetics of alkaline water reduction on Pt can be strongly affected by the accumulation of impurities on the surface. Here, we demonstrate that such impurity effects can play a role even when the highest purity, pretreated NaOH electrolyte is used, which can lead to a misinterpretation of hydrogen evolution reaction (HER) activity trends. We show that the impurity accumulation time of a chosen electrochemical protocol plays a crucial role in the extent of surface contamination and the resulting drift in HER current. By incorporating intermittent surface cleaning into the measurement sequence, we effectively mitigated contamination accumulation effects. However, the HER activity still largely depends on the electrolyte impurity levels. We argue, therefore, that optimization of both the measurement method and the purity of the chemicals is essential for minimizing contamination effects and provide recommendations for employing this integrated approach to prevent systematic errors.
Akker et al. (2026) studied this question.