The above-demonstrated electrochromic functionality occurs at potentials that are lower than required for electrocatalytic water splitting. Upon increasing the potential higher than 1.22 V, catalytic oxidation of water occurs, as indicated by the formation of bubbles on the surfaces of the colorless MA and the Pt wire (Figure ). The CV indicates oxygen evolution by the increase in the catalytic wave (Figure ). The catalytic current is significantly higher than that observed for bare FTO/glass. The corresponding Tafel plot shows a slope of 230 mV dec -1 , which has been observed for electrocatalysis by MOFs (Figure ). Electrolysis at a constant potential of 1.75 V (vs Ag/Ag + ) was characterized by a gradually increasing current density until a plateau was reached (1.5 h) and a current density of ∼7.2 mA/cm 2 was retained for an additional 5.5 h (Figure ). In addition, in this experiment, bare FTO/glass displayed a much lower (= fourfold) catalytic current under the same conditions. Gas chromatography (GC) analysis of the gas mixture in the headspace of the working compartment of the airtight electrochemical cell confirmed the formation of 537 μmol of H2 after a 4.5 h reaction time (≈ 268.5 μmol of O2). Controlled potential electrolysis (CPE) indicated that 148 C of charge passed (the active surface area = 2.0 cm 2 ), corresponding to a Faradaic efficiency (FE) of 70% (see Supporting Information for details). The turnover frequency (TOF) was estimated to be 0.12 s -1 (see Supporting Information for details). Anodization has been observed by others, indicating that an electrochemically driven process activates the catalyst. The initial anodization process of ~1.5 h markedly improved the catalytic activity; it may be associated with structural changes within the films. Apparently, the catalytic current was not affected when the electrolyte solution was replaced after 6 h of electrolysis, and the experiment was continued with the same MA for another 8 h (Figure ). CV measurements of the used electrolyte solutions (using bare FTO electrodes) do not reveal any redox-activity indicating that no functional material is being dissolved during CPE. Therefore, changes in the electrolyte solution or the buildup of H2 and O2 appear not to play a role in the efficiency of the catalytic process. Under the applied oxidative conditions in water, palladium oxide particles are expected to form, which has been confirmed by both scanning electron microscope (SEM) and CV measurements (vide infra).