Investigation of Perovskite Structures as Oxygen-Exchange Redox Materials for Hydrogen Production from Thermochemical Two-Step Water-Splitting Cycles

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• 作者：Antoine Demont ; St茅phane Abanades ; Eric Beche
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：June 19, 2014
• 年：2014
• 卷：118
• 期：24
• 页码：12682-12692
• 全文大小：683K
• 年卷期：v.118,no.24(June 19, 2014)
• ISSN：1932-7455

文摘

This study addresses the synthesis, characterization, and thermochemical redox performance evaluation of perovskites and parent structures (Ruddlesden鈥揚opper phases) as a class of oxygen-exchange materials for hydrogen generation via solar two-step water splitting. The investigated materials are La_xSr_1鈥?i>xMO₃ (M = Mn, Co, Fe), Ba_xSr_1鈥?i>x(Co,Fe)O₃, LaSrCoO₄, and LaSrFeO₄, also used as mixed ionic-electronic conductors in fuel cells. Temperature-programmed reduction, powder X-ray diffraction, and thermogravimetric analysis were used to obtain a preliminary assessment of these materials performances. Most of the perovskites studied here stand out by larger thermal reduction capabilities and oxygen vacancies formation at modest temperatures in the range 1000鈥?400 掳C when compared with reference nonstoichiometric compounds such as spinel ferrites or fluorite-structured ceria-based materials. In addition, these materials offer noticeable access to metallic valence transitions during reoxidation in steam atmosphere that are not available in stoichiometric oxides. The promising behaviors characterized here are discussed in regard to the crystal chemistry of the perovskite and parent phases.