TY - JOUR
T1 - A First-Principles-Based Sub-Lattice Formalism for Predicting Off-Stoichiometry in Materials for Solar Thermochemical Applications
T2 - The Example of Ceria
AU - Sai Gautam, Gopalakrishnan
AU - Stechel, Ellen B.
AU - Carter, Emily A.
N1 - Publisher Copyright:
© 2020 Wiley-VCH GmbH
PY - 2020/9/1
Y1 - 2020/9/1
N2 - Theoretical models that reliably can predict off-stoichiometry in materials via accurate descriptions of underlying thermodynamics are crucial for energy applications. For example, transition-metal and rare-earth oxides that can tolerate a large number of oxygen vacancies, such as CeO2 and doped CeO2, can split water and carbon dioxide via a two-step, oxide-based solar thermochemical (STC) cycle. The search for new STC materials with a performance superior to that of state-of-the-art CeO2 can benefit from predictions accurately describing the thermodynamics of oxygen vacancies. The sub-lattice formalism, a common tool used to fit experimental data and build temperature-composition phase diagrams, can be useful in this context. Here, sub-lattice models are derived solely from zero-temperature quantum mechanics calculations to estimate fairly accurate temperature- and oxygen-partial-pressure-dependent off-stoichiometries in CeO2 and Zr-doped CeO2. Physical motivations for deriving some of the “excess” sub-lattice model parameters directly from quantum mechanical calculations, instead of fitting to minimize deviations from experimental and/or theoretical data, are identified. Important limitations and approximations of the approach used are specified and extensions to multi-cation oxides are also suggested to help identify novel candidates for water and carbon dioxide splitting and related applications.
AB - Theoretical models that reliably can predict off-stoichiometry in materials via accurate descriptions of underlying thermodynamics are crucial for energy applications. For example, transition-metal and rare-earth oxides that can tolerate a large number of oxygen vacancies, such as CeO2 and doped CeO2, can split water and carbon dioxide via a two-step, oxide-based solar thermochemical (STC) cycle. The search for new STC materials with a performance superior to that of state-of-the-art CeO2 can benefit from predictions accurately describing the thermodynamics of oxygen vacancies. The sub-lattice formalism, a common tool used to fit experimental data and build temperature-composition phase diagrams, can be useful in this context. Here, sub-lattice models are derived solely from zero-temperature quantum mechanics calculations to estimate fairly accurate temperature- and oxygen-partial-pressure-dependent off-stoichiometries in CeO2 and Zr-doped CeO2. Physical motivations for deriving some of the “excess” sub-lattice model parameters directly from quantum mechanical calculations, instead of fitting to minimize deviations from experimental and/or theoretical data, are identified. Important limitations and approximations of the approach used are specified and extensions to multi-cation oxides are also suggested to help identify novel candidates for water and carbon dioxide splitting and related applications.
KW - density functional theory
KW - off-stoichiometric materials
KW - solar thermochemical water splitting
KW - sub-lattice models
KW - thermodynamic modeling
UR - http://www.scopus.com/inward/record.url?scp=85089456141&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85089456141&partnerID=8YFLogxK
U2 - 10.1002/adts.202000112
DO - 10.1002/adts.202000112
M3 - Article
AN - SCOPUS:85089456141
SN - 2513-0390
VL - 3
JO - Advanced Theory and Simulations
JF - Advanced Theory and Simulations
IS - 9
M1 - 2000112
ER -