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High Redox Capacity of Al‐Doped La 1− x Sr x MnO 3− δ Perovskites for Splitting CO 2 and H 2 O at Mn‐Enriched Surfaces
Author(s) -
Ezbiri M.,
Becattini V.,
Hoes M.,
Michalsky R.,
Steinfeld A.
Publication year - 2017
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201601869
Subject(s) - strontium , manganese , redox , x ray photoelectron spectroscopy , stoichiometry , perovskite (structure) , chemistry , doping , metal , alkaline earth metal , strontium titanate , inorganic chemistry , redistribution (election) , analytical chemistry (journal) , materials science , crystallography , thin film , nanotechnology , physics , nuclear magnetic resonance , chromatography , politics , political science , optoelectronics , organic chemistry , law
Perovskites are attractive candidates for the solar‐driven thermochemical redox splitting of CO 2 and H 2 O into CO and H 2 (syngas) and O 2 . This work investigates the surface activity of La 1− x Sr x Mn 1− y Al y O 3− δ (0≤ x ≤1, 0≤ y ≤1) and La 0.6 Ca 0.4 Mn 0.6 Al 0.4 O 3− δ . At 1623 K and 15 mbar O 2 , the oxygen non‐stoichiometry of La 0.2 Sr 0.8 Mn 0.8 Al 0.2 O 3− δ increases with the strontium content and reaches a maximum of δ =0.351. X‐ray photoelectron spectroscopy analysis indicates that manganese is the only redox‐active metal at the surface. All La 1− x Sr x Mn 1− y Al y O 3− δ compositions exhibit surfaces enriched in manganese and depleted in strontium. We discuss how these compositional differences of the surface from the bulk lead to the beneficially higher reduction extents and lower strontium carbonate concentrations at the aluminum‐doped surfaces. Using first principles calculations, we validate the experimental reduction trends and elucidate the mechanism of the partial electronic charge redistribution upon perovskite reduction.