Partial substitution of B cation in La0.6Sr0.4MnO3 perovskites: A promising strategy to improve the redox properties useful for solar thermochemical water and carbon dioxide splitting

Mixed perovskites, described by the formula La0.6Sr0.4Mn1-xFexO3-delta with x ranging from 0 to 1, were prepared and tested as potential catalysts for the solar thermochemical water and carbon dioxide splitting. The increase of iron amount promotes the reduction step according to the trend of the starting reduction temperatures; on the other hand, the reactivity towards H2O and CO2 seems to be fostered by high Mn contents. The highest amounts of oxygen evolved during thermogravimetric analysis and hydrogen produced during splitting tests occur to the sample with x = 1 even if a non-monotonic trend with iron substitution is appreciated. Instead, CO amount progressively decreases by increasing iron content. The results reported in this work indicate that the formulation of bi-functional systems with two active sites, one showing good self-reduction the other good reactivity towards splitting reactions, is the best route to prepare materials with larger intrinsic H-2 and CO productivity as well as lower reduction/oxidation temperature.