Sr- and Mn-doped LaAlO3−δ for solar thermochemical H2 and CO production

Principles of doping ceria for the solar thermochemical redox splitting of H2O and CO2

“…Thus, DH red must be greater than 2.51 eV (242 kJ mol À1 ) to split steam. 5 Additionally, materials with high reduction enthalpies require high reduction temperatures and result in high H 2 O conversion; conversely, materials with low reduction enthalpies reduce at lower temperatures but require a larger temperature swing between the reduction and oxidation steps or result in low H 2 [12][13][14] and ceria (CeO 2 ). 15,16 Among these, ceria has become the benchmark material because of its rapid kinetics, and long term stability.…”

Thermodynamic and kinetic assessments of strontium-doped lanthanum manganite perovskites for two-step thermochemical water splitting

“…5 Two classes of non-stoichiometric (variable valence) oxides have been evaluated for solar-driven thermochemical fuel production: uorites based on ceria (CeO 2Àd ) [4][5][6][7][8] and perovskites based on lanthanum manganite (LaMnO 3Àd , in which d may be < 0) 9,10 or on lanthanum aluminate (LaAlO 3Àd ). 11 The relatively extensive studies of the ceria-based class of compounds has revealed that this group of materials generally requires rather high temperatures, >1500 C, to induce reduction of the oxide to an extent that the cycling yields non-trivial amounts of fuel.…”

Redox chemistry of CaMnO3 and Ca0.8Sr0.2MnO3 oxygen storage perovskites

“…17 This is a fundamental limitation of the crystal motifs of these materials, and thus perovskite oxides, regardless of composition, will likely have a lower entropy of vacancy formation than ceria. This has important implications for designing materials for thermochemical fuel production cycles, where perovskites 28,29 have been suggested as a lower temperature alternative to the ceria cycle. 30 In this particular application, the oxide must have a large enough enthalpy of reduction Dh to reduce steam or carbon dioxide (>300 kJ mol À1 ).…”