A novel CeO₂–<i>x</i>SnO₂/Ce₂Sn₂O₇ pyrochlore cycle for enhanced solar thermochemical water splitting

Abstract

A novel CeO 2 –xSnO 2 /Ce 2 Sn 2 O 7 pyrochlore stoichiometric redox cycle with superior H 2 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 CeO 2 and SnO 2 occurred for all the CeO 2 –xSnO 2 (x = 0.05–0.20) solid compounds, forming thermodynamically stable Ce 2 Sn 2 O 7 pyrochlore rather than metastable CeO 2‐δ . Consequently, substantially higher reduction extents were achieved owing to the reduction of Ce IV to Ce III . Moreover, in the subsequent reoxidation with H 2 O (800°C), H 2 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 CeO 2 and SnO 2 and the concomitant reoxidation of Ce III to Ce IV . The H 2 O‐splitting performance for CeO 2 –0.15SnO 2 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