Layered Bismuth Oxyfluoride Nitrates Revealing Large Second-Harmonic Generation and Photocatalytic Properties

Eun Jeong Cho; Seung-Jin Oh; Hongil Jo; Junsu Lee; Tae-Soo You; Kang Min Ok

doi:10.1021/acs.inorgchem.8b03343

Layered Bismuth Oxyfluoride Nitrates Revealing Large Second-Harmonic Generation and Photocatalytic Properties

Inorg Chem. 2019 Feb 4;58(3):2183-2190. doi: 10.1021/acs.inorgchem.8b03343. Epub 2019 Jan 16.

Authors

Eun Jeong Cho¹, Seung-Jin Oh¹, Hongil Jo¹, Junsu Lee², Tae-Soo You², Kang Min Ok¹

Affiliations

¹ Department of Chemistry , Chung-Ang University , Seoul 06974 , Republic of Korea.
² Department of Chemistry , Chungbuk National University , Cheongju , Chungbuk 28644 , Republic of Korea.

PMID: 30648864
DOI: 10.1021/acs.inorgchem.8b03343

Abstract

Two novel bismuth oxyfluoride nitrates, Bi₂OF₃(NO₃) and Bi₆O₆F₅(NO₃), have been synthesized via hydrothermal reactions. Whereas Bi₂OF₃(NO₃) crystallizes in the centrosymmetric (CS) hexagonal space group, P6₃/ m, Bi₆O₆F₅(NO₃) crystallizes in the polar noncentrosymmetric (NCS) trigonal space group, R3. The backbones of the title compounds reveal double layered structures composed of asymmetric BiF₃(O/F)₃ or BiO₃F₂ polyhedra and NO₃ trigonal planar groups. The diffuse reflectance spectra indicate that Bi₂OF₃(NO₃) and Bi₆O₆F₅(NO₃) contain wide band gaps of 3.5 and 4.0 eV, respectively. Powder second-harmonic generation (SHG) measurements suggest that NCS Bi₆O₆F₅(NO₃) is Type-I phase-matchable and has a large SHG response of ca. 3 times that of KH₂PO₄ (KDP). Electron localization function (ELF) analysis indicates that the large SHG efficiency of Bi₆O₆F₅(NO₃) is attributed to the synergistic effect of the alignment of NO₃^- trigonal planar groups and strong interactions between highly polarizable lone pair electrons on Bi³⁺ and π-delocalized electrons in NO₃^- groups. Bi₂OF₃(NO₃) also exhibits a very good photocatalytic degradation efficiency of Rhodamine B (RhB) under the UV light irradiation.