Temperature dependent mechanism transition effect stabilized ruthenium-based oxides for water oxidation in proton exchange membrane electrolyzer

Oxygen evolution reaction (OER), as the anodic reaction of many electrochemical devices, plays a crucial role in such energy conversion process. However, the poor OER stability of non-iridium-based materials has tremendously limited the large-scale application of related devices. Here, using a novel home-made operando differential electrochemical mass spectroscopy, for the first time we report a temperature dependent mechanism transition (TDMT) effect of RhRu3Ox, a non-iridium-based electrocatalyst, in OER process, which makes us realize the important role of temperature in triggering OER mechanism transition, and further enriches our toolbox for manipulating OER kinetics. To evaluate the potential of RhRu3Ox for practical applications, we assembled it as an anode in a proton exchange membrane (PEM) electrolyzer, demonstrating its stability at room temperature for over 1000 hours at 200 mA cm-2 compared with the unstable pristine RuO2. Techno-economic analysis shows that the cost of H2 production using solar photovoltaic and onshore wind as power sources is already lower than the global average levelized cost of H2 from coal. Density functional theory studies reveal that the existence of kinetic barrier related to lattice oxygen activation might be the reason for the OER TDMT of RhRu3Ox at elevated temperature.