Electronic Band Structure, Optical Properties, and Photocatalytic Hydrogen Production of Barium Niobium Phosphate Compounds (BaO-Nb2O5-P2O5)

• Published in: European Journal of Inorganic Chemistry Vol. 2011; no. 14; pp. 2206 - 2210
• Main Authors: Cho, In Sun, Kim, Dong Wook, Kim, Dong Hoe, Shin, Seong Sik, Noh, Tae Hoon, Kim, Dong Wan, Hong, Kug Sun
• Format: Book Review Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.05.2011; WILEY‐VCH Verlag
• Subjects: Ceramics; Electronic structure; Luminescence; Solid-phase synthesis; Water splitting
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201001096

Barium niobium phosphate compounds (BaNb2P2O11 and Ba3Nb2P4O18), with corner‐sharing NbO6 octahedra as well as PO4 tetrahedra, were prepared by a conventional solid‐state reaction method, and their optical properties, electronic band structure, and photocatalytic activity were investigated. The powders were characterized by X‐ray powder diffraction (XRD), field‐emission SEM (FESEM), high‐resolution TEM (HRTEM), and UV/Vis and fluorescence spectroscopy. Both compounds exhibit similar optical band gaps, 3.55 eV for BaNb2P2O11 and 3.58 eV for Ba3Nb2P4O18. However, photoluminescence spectra revealed that a radiative recombination process of charge carriers is dominant in Ba3Nb2P4O18 (strong blue‐white emission at 300 K) under UV irradiation, whereas no obvious emission was observed from BaNb2P2O11. The photocatalytic activity for the evolution of H2 from the splitting of pure water was evaluated. BaNb2P2O11, which has a smaller photon emission at room temperature, exhibited a much higher photocatalytic activity than Ba3Nb2P4O18. The difference in the photocatalytic activity of the two compounds is attributed to their different electronic band structures, resulting from their different crystal‐structure environments. Two barium niobium phosphate compounds (BaNb2P2O11 and Ba3Nb2P4O18) were prepared by a conventional solid‐state reaction method. Although both compounds have similar optical band gaps (ca. 3.6 eV), their optical and photocatalytic behavior differs due to their different conduction band constructions, which results from their different crystal structure environments.