Preparation of the setups and the thin films -Extensive cleaning has been performed to eliminate any organic and inorganic impurity contributions that could potentially affect the stability of the studied electrocatalysts. Prior to the set of degradation experiments, all the glassware was soaked in both a base bath (mixture of KOH and isopropanol) and an acid bath (mixture of conc. HNO3 and H2SO4) as well as boiled in distilled water 3 times. Before each experiment, the HT-cell was heated for 2 hours at 90 °C in 0.1 M HClO4, then boiled in Milli-Q water for 2 hours, whereas the RT-cell was boiled in distilled water for 1 hour.