title: Preparation of N-doped CaNb2O6 nanoplates with ellipsoid-like morphology and their photocatalytic activities under visible-light irradiation.
abstract: Nitrogen-doped CaNb2O6 nanoplates with an ellipsoid-like morphology were prepared using the hydrothermal method, followed by heat treatment at various temperatures in an NH3 atmosphere. The prepared powders were characterized using X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectroscopy. It was found that the nitrogen doping in the CaNb2O6 nanoplates led to the formation of nanoparticles with a size of 10 nm at the surface and the red-shift of the light absorption edge into the visible light region. From the electronic band structure calculation using density functional theory (DFT), this was found to be caused by the broadening of the top of the valence band due to the hybridization of the O 2p and N 2p orbitals induced by the substitution of the nitrogen for the lattice oxygen. Compared to the un-doped powder, the N-doped CaNb2O6 nanoplate powder exhibited higher photocatalytic activities for the degradation of rhodamine B dye solution under visible light irradiation (> 420 nm). This higher photocatalytic activity was attributed to the higher optical absorption (smaller band gap) and higher surface area resulting from the nitridation process.
authors.affiliation: Department of Materials Science and Engineering, College of Engineering, Seoul National University, Shillim-dong, San 56-1, Gwanak-gu, Seoul 151-744, Korea.
authors.forename: In-Sun
authors.initials: IS
authors.lastname: Cho
authors.forename: Dong Wook
authors.initials: DW
authors.lastname: Kim
authors.forename: Tae Hoon
authors.initials: TH
authors.lastname: Noh
authors.forename: Sangwook
authors.initials: S
authors.lastname: Lee
authors.forename: Dong Kyun
authors.initials: DK
authors.lastname: Yim
authors.forename: Kug Sun
authors.initials: KS
authors.lastname: Hong