Investigation into Ca-Doped LaMnCoO3 Perovskite Oxides for Thermochemical Water Splitting

Abstract

Two-step thermochemical water splitting (II-TWS), involving concentrating sunlight, has become prominent for green hydrogen production that does not require H2/O2 separation steps at high temperatures. The kinetics and thermodynamics of redox reactions are important factors that determine hydrogen production efficiency. This efficiency is strongly influenced by the structural properties of active materials used in II-TWS reactions. Perovskite oxides are one of the promising active materials for II-TWS due to their superior oxygen exchange abilities. In this study, La1-xCaxMn0.8Co0.2O3 (LCMC) type perovskites with a wide range of calcium substitution (x = 0, 0.2, 0.4, 0.6, 0.8) were examined for hydrogen production in terms of their structural properties, kinetics, O2/H2 production capacities, and cyclabilities. According to our test results, La0.8Ca0.2Mn0.8Co0.2O3 (LCMC8282) and La0.6Ca0.4Mn0.8Co0.2O3 (LCMC6482) displayed higher H2 production capacity with 256 μmol g−1 and 88 μmol g−1 as compared to the other selected perovskites. After three consecutive cycles, La0.8Ca0.2Mn0.8Co0.2O3 lost 83% of its H2 production capacity whereas La0.6Ca0.4Mn0.8Co0.2O3 preserved 61% of its H2 production capacity achieved in the first cycle.