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

- Bi14MoO24 with layered δ-Bi2O3-type structure was synthesized by co-precipitation.
- The nanoparticles show high absorption in UV-vis wavelength region (Eg = 2.48 eV).
- The photocatalytic activity was markedly enhanced for Bi14MoO24 (7Bi2O3·MoO3).
- The mechanism of this photocatalysis system was proposed.

The bismuth molybdate oxide of Bi14MoO24 (7Bi2O3·MoO3) was synthesized by the co-precipitation route. The samples developed into the uniform nanoparticles around 50 nm. 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 500 nm (Eg = 6.2 - 2.48 eV). 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.