title: Crucial Role of Donor Density in the Performance of Oxynitride Perovskite LaTiO2N for Photocatalytic Water Oxidation.
abstract: LaTiO2N photocatalysts were prepared by thermal ammonolysis of flux-synthesized La2Ti2O7and La2TiO5, and were investigated for water oxidation. Though LaTiO2N derived from La2TiO5appears defect-free by UV/Vis/near-IR and electron paramagnetic resonance (EPR) spectroscopy, its performance is much lower than that of conventional La2Ti2O7-derived LaTiO2N with defects. It is shown by Mott-Schottky analysis that La2TiO5-derived LaTiO2N has significantly lower donor density; this can result in insufficient built-in electric field for the separation of photogenerated electrons and holes. The lower donor density is also consistent with the smaller difference between the Fermi level and the valence-band maximum, which accounts for a lower oxidative power of the holes. In light of this discovery, the donor density was increased substantially by introducing anion vacancies through annealing in Ar. This resulted in improved performance. The CoOx-assisted La2TiO5-derived LaTiO2N annealed at 713 °C has a higher quantum efficiency (25 %) at 450 nm than high-performance conventional CoOx/LaTiO2N (21 %).
authors.affiliation: Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P. R. China.
authors.forename: Feng-Qiang
authors.initials: FQ
authors.lastname: Xiong
authors.affiliation: Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P. R. China.
authors.forename: Lipeng
authors.initials: L
authors.lastname: Wan
authors.affiliation: Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P. R. China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai, 600036, Tamil Nadu, India.
authors.forename: Tiju
authors.initials: T
authors.lastname: Thomas
authors.affiliation: Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, 14853-1301, USA.
authors.forename: Francis J
authors.initials: FJ
authors.lastname: DiSalvo
authors.affiliation: Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P. R. China.
authors.forename: Minghui
authors.initials: M
authors.lastname: Yang
mesh_terms: D002384:Catalysis; D007811:Lanthanum / Q000737:chemistry*; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D055668:Photochemical Processes; D013696:Temperature; D014025:Titanium / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D010087:Oxides; D014867:Water; D007811:Lanthanum; D014025:Titanium
keywords: ammonolysis; oxidation; oxynitrides; perovskite phases; photocatalysis