title: High Redox Capacity of Al-Doped La1-xSrxMnO3-δPerovskites for Splitting CO2and H2O at Mn-Enriched Surfaces.
abstract: Perovskites are attractive candidates for the solar-driven thermochemical redox splitting of CO2and H2O into CO and H2(syngas) and O2. This work investigates the surface activity of La1-xSrxMn1-yAlyO3-δ(0≤x≤1, 0≤y≤1) and La0.6Ca0.4Mn0.6Al0.4O3-δ. At 1623 K and 15 mbar O2, the oxygen non-stoichiometry of La0.2Sr0.8Mn0.8Al0.2O3-δincreases 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 La1-xSrxMn1-yAlyO3-δcompositions 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.
authors.affiliation: Department of Mechanical and Process Engineering, ETH Zürich, 8092, Zürich, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Ezbiri
authors.affiliation: Department of Mechanical and Process Engineering, ETH Zürich, 8092, Zürich, Switzerland.
authors.forename: V
authors.initials: V
authors.lastname: Becattini
authors.affiliation: Department of Mechanical and Process Engineering, ETH Zürich, 8092, Zürich, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Hoes
authors.affiliation: Department of Mechanical and Process Engineering, ETH Zürich, 8092, Zürich, Switzerland.
authors.forename: R
authors.identifier: 0000-0002-9535-2871
authors.initials: R
authors.lastname: Michalsky
authors.affiliation: Department of Mechanical and Process Engineering, ETH Zürich, 8092, Zürich, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Steinfeld
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry*; D002254:Carbonates / Q000737:chemistry; D007811:Lanthanum / Q000737:chemistry*; D008345:Manganese / Q000737:chemistry*; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D013324:Strontium / Q000737:chemistry*; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D017610:Calcium Compounds; D002254:Carbonates; D010087:Oxides; D014867:Water; C059910:perovskite; D002245:Carbon Dioxide; D008345:Manganese; D007811:Lanthanum; D000535:Aluminum; D014025:Titanium; D010100:Oxygen; D013324:Strontium
keywords: X-ray photoelectron spectroscopy; perovskites; redox chemistry; solar fuels; surface chemistry