Effect of Nb doping on structural, optical and photocatalytic properties of flame-made TiO sub(2) nanopowder

TiO sub(2):Nb nanopowders within a dopant concentration in the range of 0.1-15 at.% were prepared by one-step flame spray synthesis. Effect of niobium doping on structural, optical and photocatalytic properties of titanium dioxide nanopowders was studied. Morphology and structure were investigated by means of Brunauer-Emmett-Teller isotherm, X-ray diffraction and transmission electron microscopy. Diffuse reflectance and the resulting band gap energy were determined by diffuse reflectance spectroscopy. Photocatalytic activity of the investigated nanopowders was revised for the photodecomposition of methylene blue (MB), methyl orange (MO) and 4-chlorophenol under UVA and VIS light irradiation. Commercial TiO sub(2)-P25 nanopowder was used as a reference. The specific surface area of the powders was ranging from 42.9 m super(2)/g for TiO sub(2):0.1 at.% Nb to 90.0 m super(2)/g for TiO sub(2):15 at.% Nb. TiO sub(2):Nb particles were nanosized, spherically shaped and polycrystalline. Anatase was the predominant phase in all samples. The anatase-related transition was at 3.31 eV and rutile-related one at 3.14 eV. TiO sub(2):Nb nanopowders exhibited additional absorption in the visible range. In comparison to TiO sub(2)-P25, improved photocatalytic activity of TiO sub(2):Nb was observed for the degradation of MB and MO under both UVA and VIS irradiation, where low doping level (Nb