Unraveling Thermodynamics, Stability, and Oxygen Evolution Activity of Strontium Ruthenium Perovskite Oxide

Extensive investigations in understanding the functional mechanisms of metal oxides behind oxygen evolution have been carried out since an electrolyzer has demonstrated promising possibilities as a device to produce hydrogen for electrochemical energy conversion systems. In particular, perovskite oxides are reputable for high activity toward the oxygen evolution reaction (OER). Here, we revisited the list of active perovskite oxides constructed based on theoretical oxygen binding energies of reaction intermediates to the catalyst surface. From this list, Ru-based perovskites, i.e. SrRuO3 and LaRuO3, have been predicted as active perovskites to exhibit a particularly high OER activity. We report on the stability of nanoscaled SrRuO3 perovskite prepared by a simple and scalable flame synthesis method. Attempts to obtain LaRuO3 were made; however, its DFT calculated phase diagram suggests that its perovskite phase is not thermodynamically stable, which supports our experimental results such that only a mixtu...