An Exploration of Perovskite Materials for Thermochemical Water Splitting

Citation

Yang, Chih-Kai (2015) An Exploration of Perovskite Materials for Thermochemical Water Splitting. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z91834GB. https://resolver.caltech.edu/CaltechTHESIS:09082014-140216721

Abstract

Two-step thermochemical water splitting is a promising technology for the hydrogen production of solar energy. This process possesses the advantages of utilizing the full solar spectrum, producing flexible fuels, and requiring no precious metal catalysts. It furthermore temporally separates the oxygen release and hydrogen production steps, eliminating the possibility of O₂ and H₂ recombination. Ceria, which undergoes non-stoichiometric changes in oxygen content, has been demonstrated as an effective material for solar-driven thermochemical fuel production, but the process requires extremely high temperatures (~ 1600 degrees C), leading to efficiency penalties and challenges in reactor design and construction. Accordingly, the objective of this work is the development of new thermochemical reaction substrate materials which enable operation at lower temperatures and ideally increase fuel productivity and efficiency. Here we explore perovskite systems, specifically La_1-xSr_xMnO_3-δ, La_0.8Sr_0.2Mn_1-yFe_yO_3-δ, and La_0.8Sr_0.2Mn_1-yAl_yO_3-δ. The link between the solid-state chemistry, redox properties, hydrogen production, and reaction kinetic limitations will be discussed. This study aims to learn how to design and tailor the good catalytic oxides for solar-driven thermochemical water splitting application.

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