The total protocol used for follow-up measurements on Mn70Ti30Ox and Mn90Co10Ox samples is shown in Figure . The activity is assessed through multiple 30-second chronopotentiometric (CP) steps at 0.1, 0.2, 0.5, 1, 2, 5 mA cm -2 to allow a Tafel analysis. As higher currents are reached during this protocol, the potential was iR corrected using the resistance measured through electrochemical impedance spectroscopy (EIS) between 100 -100,000 Hz at open circuit potential. The CP holds are followed by the same AST outlined earlier (120 cyles between 0 and 1 mA cm -2 for 1 s each) before concluding with another Tafel analysis with the same current steps. Finally, another electrochemical protocol is designed to study the operando dissolution behavior of Mn70Ti30Ox. The objective was to record the activity, dissolution behavior, and change in surface area over a prolonged time span, for which the protocol was applied in a loop up to 19 times. Each iteration starts with three cyclic voltammograms (CVs) between 1.1 and 1.3 VRHE. Scan rates of 25, 50, 100, and 200 mV s -1 were chosen to extract the capacitance from the capacitive current, which serves as a proxy for the electrochemical surface area. The obtained capacitance is purposely not converted to an area value as the specific capacitance for this system is unknown. However, as the change throughout the operation is more relevant, reporting the capacitance alone is thought to be sufficient. Afterward, a 30-second hold at 1 mA cm -2 and 80 AST cycles between 0 and 1 mA cm -2 are performed to roughly mimic testing conditions applied previously.