Oxygen Exchange in Dual-Phase La<sub>0.65</sub>Sr<sub>0.35</sub>MnO<sub>3</sub>–CeO<sub>2</sub> Composites for Solar Thermochemical Fuel Production
Alexander H. Bork, Alfonso J. Carrillo, Zachary D. Hood, Bilge Yildiz, Jennifer L. M. Rupp
Abstract
Increasing the capacity and kinetics of oxygen exchange in solid oxides is important to improve the performance of numerous energy-related materials, especially those for the solar-to-fuel technology. Dual-phase metal oxide composites of La 0.65 Sr 0.35 MnO 3 – x %CeO 2, with x = 0, 5, 10, 20, 50, and 100, have been experimentally investigated for oxygen exchange and CO 2 splitting via thermochemical redox reactions. The prepared metal oxide powders were tested in a temperature range from 1000 to 1400 °C under isothermal and two-step cycling conditions relevant for solar thermochemical fuel production. We reveal synergetic oxygen exchange of the dual-phase composite La 0.65 Sr 0.35 MnO 3 –CeO 2 compared to its individual components. The enhanced oxygen exchange in the composite has a beneficial effect on the rate of oxygen release and the total CO produced by CO 2 splitting, while it has an adverse effect on the maximum rate of CO evolution. Ex situ Raman and XRD analyses are used to shed light on the relative oxygen content during thermochemical cycling. Based on the relative oxygen content in both phases, we discuss possible mechanisms that can explain the observed behavior. Overall, the presented findings highlight the beneficial effects of dual-phase composites in enhancing the oxygen exchange capacity of redox materials for renewable fuel production.