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High‐temperature structural stability of ceria‐based inverse opals
Author(s) -
Casillas Danielle C.,
Wilkinson Dan C.,
Lai ChunHan,
Wilke Stephen K.,
Ignatowich Michael J.,
Haile Sossina M.,
Dunn Bruce S.
Publication year - 2017
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.14781
Subject(s) - porosity , materials science , inverse , annealing (glass) , thermal stability , scanning electron microscope , kinetics , chemical engineering , porous medium , hydrogen , mineralogy , analytical chemistry (journal) , composite material , chemistry , mathematics , geometry , physics , organic chemistry , chromatography , quantum mechanics , engineering
The use of ceria‐based inverse opals as a catalyst system for the thermochemical production of fuels from sunlight offers the potential of improved fuel production kinetics over materials with random porosity. Quantitative methods for characterizing ordered porosity are lacking, thus limiting the ability to predict the lifetime of ordered structures at elevated temperatures. In the present work, Fourier transform image analysis was used to determine the effect of composition and temperature on ordered porosity for a series of CeO 2 ‐ZrO 2 inverse opals having pore sizes ranging from 300 nm to 1 μm. An order parameter, γ, derived from the image analysis, was applied to scanning electron microscopy images and used to determine the degree of order in the inverse opal. The thermal stability studies indicate that loss of ordered porosity is highly dependent on temperature and that gas cycling effects have a minor effect on periodicity. A minimum Zr content of 20 at.% is necessary to retain periodicity for annealing up to 1000°C with pore diameters larger than 1 μm. These results show that CeO 2 ‐ZrO 2 inverse opals can be used at higher temperatures than previously thought for efficient thermochemical hydrogen production without loss of the benefits associated with ordered porosity.