Light Absorption Properties and Electronic Band Structures of Lead Titanium Oxyfluoride Photocatalysts Pb 2 Ti 4 O 9 F 2 and Pb 2 Ti 2 O 5.4 F 1.2

作者：Haruki Wakayama, Keishu Utimula, Tom Ichibha, Ryo Kuriki, Kenta Hongo, Ryo Maezono, Kengo Oka, Kazuhiko Maeda · 发表于：The Journal of Physical Chemistry C · 年份：2018 · DOI：10.1021/acs.jpcc.8b08953 · 被引用次数：38 · 研究领域：Advanced Photocatalysis Techniques、Ga2O3 and related materials、Inorganic Fluorides and Related Compounds

Light absorption capability and electronic band structure are both fundamental information for the development of a new photocatalyst. Here, we investigated two oxyfluoride photocatalysts Pb 2 Ti 4 O 9 F 2 and Pb 2 Ti 2 O 5.4 F 1.2, which were active for H 2 evolution in the presence of a sacrificial reagent, by means of X-ray diffraction, UV–visible diffuse reflectance spectroscopy, electrochemical impedance spectroscopy, and density functional theory calculations. Pb 2 Ti 4 O 9 F 2 and Pb 2 Ti 2 O 5.4 F 1.2 show absorption edges at around 410 and 510 nm, respectively, corresponding to band gaps of 3.0 and 2.4 eV. The different band gap values of the two materials are mainly due to their valence band maximum (VBM); the VBM of Pb 2 Ti 4 O 9 F 2 is positioned at approximately 0.9 V more positive than that of Pb 2 Ti 2 O 5.4 F 1.2 . The significantly different VBM positions in these oxyfluorides could be explained in terms of the orbital interaction between Pb 6s/6p and O 2p in the valence band, where the shorter Pb–O bond in Pb 2 Ti 2 O 5.4 F 1.2 reinforced the interaction, leading to more elevated VBM and a narrower band gap.