Improvement of visible-light photo catalytic activity of BiNbO4 by Ti doping

Abstract

Optimized doped BiNbO4 is necessary for efficient visible light harvesting and perform excellent visible-light photocatalytic activity in degradation of organic pollutants. The Ti doped BiNbO4 polycrystalline powders of BiNb1-xTixO4 (x = 0, 0.03, 0.05, 0.08, 0.10, 0.15) were synthesized by a traditional solid-state reaction method. The effects of Ti dopant on the structural, optical and visible-light photocatalytic properties were investigated. The X-ray diffraction (XRD) results show that all the samples maintain orthorhombic structure with a space group of Pnna without any impurity phases, suggesting the Ti ions were substitutionally incorporated in the BiNbO4 lattice. With the increase of Ti concentration, the particle sizes and the specific surface area have no obviously variation, while the band gap (Eg) of each sample is slightly decreased compared with the pure BiNbO4. Ti doped samples exhibits excellent visible-light photocatalytic properties and could be a potential candidate for photocatalytic degradation of organic pollutants. The improved visible-light photocatalytic activity could be attributed to the enhancement of oxidation-reduction power by a slight downshift of the conduction band and an upshift of the valence band.