Publications

Nonstoichiometric perovskite oxides for solar thermochemical H2 and CO production

McDaniel, Anthony H.; Ambrosini, A.; Coker, E.N.; Miller, J.E.; Chueh, W.C.; O'Hayre, R.; Tong, J.

Perovskite oxides (ABO3) are a largely unexplored class of materials in solar fuel applications. In this paper we examine the use of nonstoichiometric perovskite-type oxides in a two-step, solar-thermochemical water or carbon dioxide splitting cycle. We find that O2 begins to evolve during thermal reduction from a Sr- and Mn-doped LaAlO3 fully 300 °C lower than that of CeO2, and that these compounds will split both H2O and CO2. The yield of H2 and CO is significantly greater than CeO2, a benchmark material in solar fuels research, at a thermal reduction temperature 150 °C below that commonly reported for CeO2. In addition, the perovskite redox kinetics compare favorably to CeO2, which is known for its rapid reaction rates. We also find that an Fe-doped CaTiO3 is redox active and will split H2O, though the performance of this material is similar to that of CeO2. Finally, we introduce an experimental protocol that combines an ideal stagnation-flow reactor with detailed numerical modeling to effectively deconvolve intrinsic material behavior from interference induced by physical processes occurring inside the flow reactor. This method utilizes rate information contained within the entire time domain of the oxidation reaction, and assigns rate-governing processes to the material within the context of solid-state kinetic theory. © 2013 The Authors.