Design Principles of Perovskites for Thermochemical Oxygen Separation.
Separation and concentration of O2 from gas mixtures is central to several sustainable energy technologies, such as solar-driven synthesis of liquid hydrocarbon fuels from CO2 , H2 O, and concentrated sunlight. We introduce a rationale for designing metal oxide redox materials for oxygen separation through "thermochemical pumping" of O2 against a pO2 gradient with low-grade process heat. Electronic structure calculations show that the activity of O vacancies in metal oxides pinpoints the ideal oxygen exchange capacity of perovskites. Thermogravimetric analysis and high-temperature X-ray diffraction for SrCoO3-δ , BaCoO3-δ and BaMnO3-δ perovskites and Ag2 O and Cu2 O references confirm the predicted performance of SrCoO3-δ , which surpasses the performance of state-of-the-art Cu2 O at these conditions with an oxygen exchange capacity of 44 mmol O 2 mol SrCoO 3-δ(-1) exchanged at 12.1 μmol O 2 min(-1)  g(-1) at 600-900 K. The redox trends are understood due to lattice expansion and electronic charge transfer.
Solar Technology Laboratory, Paul Scherrer Institute, 5232 Villigen-PSI (Switzerland).|Department of Mechanical and Process Engineering, ETH Zürich, 8092 Zürich (Switzerland).
Miriam
M
Ezbiri
Solar Technology Laboratory, Paul Scherrer Institute, 5232 Villigen-PSI (Switzerland).|Present address: Sandia National Laboratories, Livermore, CA 94550 (USA).
Kyle M
KM
Allen
Department of Mechanical and Process Engineering, ETH Zürich, 8092 Zürich (Switzerland).|Present address: Institut Jean Le Rond D'Alembert, Université Pierre et Marie Curie, 78210 Saint-Cyr-l'École (France).
Maria E
ME
Gàlvez
Department of Mechanical and Process Engineering, ETH Zürich, 8092 Zürich (Switzerland). michalskyr@ethz.ch.
Ronald
R
Michalsky
Department of Mechanical and Process Engineering, ETH Zürich, 8092 Zürich (Switzerland).
Aldo
A
Steinfeld
D017610:Calcium Compounds / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D010087:Oxides / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry* / Q000302:isolation & purification*; D011312:Pressure; D013696:Temperature; D014025:Titanium / Q000737:chemistry*
D017610:Calcium Compounds; D010087:Oxides; C059910:perovskite; D014025:Titanium; D010100:Oxygen
density functional theory; oxygen evolution; oxygen reduction; perovskites; thermochemical o2 separation