title: Design Principles for Metal Oxide Redox Materials for Solar-Driven Isothermal Fuel Production.
abstract: The performance of metal oxides as redox materials is limited by their oxygen conductivity and thermochemical stability. Predicting these properties from the electronic structure can support the screening of advanced metal oxides and accelerate their development for clean energy applications. Specifically, reducible metal oxide catalysts and potential redox materials for the solar-thermochemical splitting of CO2and H2O via an isothermal redox cycle are examined. A volcano-type correlation is developed from available experimental data and density functional theory. It is found that the energy of the oxygen-vacancy formation at the most stable surfaces of TiO2, Ti2O3, Cu2O, ZnO, ZrO2, MoO3, Ag2O, CeO2, yttria-stabilized zirconia, and three perovskites scales with the Gibbs free energy of formation of the bulk oxides. Analogously, the experimental oxygen self-diffusion constants correlate with the transition-state energy of oxygen conduction. A simple descriptor is derived for rapid screening of oxygen-diffusion trends across a large set of metal oxide compositions. These general trends are rationalized with the electronic charge localized at the lattice oxygen and can be utilized to predict the surface activity, the free energy of complex bulk metal oxides, and their oxygen conductivity.
authors: Department of Mechanical and Process Engineering, ETH Zürich 8092, Zürich, Switzerland.
authors: Ronald
authors: R
authors: Michalsky
authors: Department of Chemical, Materials, and Biomolecular Engineering, University of Connecticut Storrs, CT, 06269, USA.
authors: Venkatesh
authors: V
authors: Botu
authors: School of Engineering, Brown University Providence, RI, 02912, USA.
authors: Cory M
authors: CM
authors: Hargus
authors: School of Engineering, Brown University Providence, RI, 02912, USA.
authors: Andrew A
authors: AA
authors: Peterson
authors: Department of Mechanical and Process Engineering, ETH Zürich 8092, Zürich, Switzerland; Solar Technology Laboratory, Paul Scherrer Institute 5232, Villigen, Switzerland.
authors: Aldo
authors: A
authors: Steinfeld
keywords: CO2 reduction; concentrated solar energy; density functional theory; solid oxide fuel cells; vacancy diffusion