Optical properties and visible-light driven photocatalytic performance of Bi14MoO24 semiconductor with layered δ-Bi2O3-type structure

Abstract

The bismuth molybdate oxide of Bi14MoO24 (7Bi2O3·MoO3) was synthesized by the co-precipitation route. The samples developed into the uniform nanoparticles around 50nm. Crystalline phase was verified via Rietveld XRD structural refinement. Tetragonal Bi14MoO24 is related to that the face-centered cubic (fcc) δ-phase of Bi2O3-like structure. It has more loose space with a big structure-openness than parent δ-Bi2O3. The surface microstructure and components of the photocatalysts were studied by TEM, SEM, BET, EDS and XPS measurements. The UV–vis absorption spectra showed that the band gap energy of Bi14MoO24 was greatly reduced in comparison with δ-Bi2O3. The result confirms that Bi14MoO24 can response to visible wavelength between 200 and 500nm (Eg=6.2–2.48eV). Bi14MoO24 derived from δ-Bi2O3 by incorporating Mo (7Bi2O3:MoO3) in the lattices possesses broader conduction band. This greatly benefits the mobility of the light-induced charges taking part in the photocatalytic reactions. Bi14MoO24 nanoparticles possess efficient photodegradation on Rhodamine B (RhB) dye and phenol solutions. The photocatalysis activities and mechanisms were discussed on the crystal structure characteristics and the measurements such as photoluminescence, exciton lifetime and XPS results. The layered Bi–O polyhedral structure, good photo-absorption, multivalent elements, quenched luminescence and long exciton lifetime were possibly the origin of its high photocatalytic activity in the photo-degradation.