A novel CeO2–xSnO2/Ce2Sn2O7 pyrochlore cycle for enhanced solar thermochemical water splitting

Abstract

A novel CeO2–xSnO2/Ce2Sn2O7 pyrochlore stoichiometric redox cycle with superior H2 production capacities is identified and corroborated for two‐step solar thermochemical water splitting (STWS). During the first thermal reduction step (1400°C), a reaction between CeO2 and SnO2 occurred for all the CeO2–xSnO2 (x = 0.05–0.20) solid compounds, forming thermodynamically stable Ce2Sn2O7 pyrochlore rather than metastable CeO2‐δ. Consequently, substantially higher reduction extents were achieved owing to the reduction of CeIV to CeIII. Moreover, in the subsequent reoxidation with H2O (800°C), H2 production capacities increased by a factor of 3.8 as compared to the current benchmark material ceria when x = 0.15, with the regeneration of CeO2 and SnO2 and the concomitant reoxidation of CeIII to CeIV. The H2O‐splitting performance for CeO2–0.15SnO2 was reproducible over seven consecutive redox cycles, indicating the material was also robust. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3450–3462, 2017