Synthesis, characterization and photocatalytic activity of lanthanide (Ce, Pr and Nd) orthovanadates

A new approach to the synthesis of the lanthanide orthovanadates CeVO4, PrVO4, and NdVO4 is proposed. These compounds exhibit a tetragonal zircon structure, crystallizing in the space group I4(1)/amd with a = 7.3733(4) angstrom, c = 6.4909(4) angstrom, and Z = 4. The crystal structure has been analyzed by powder X-ray diffraction and FTIR and UV-visible spectroscopies. Particle sizes were found to be in the range of 200-300 nm as seen by scanning electron microscopy, and energy-dispersive X-ray analysis indicated the formation of LnVO(4). Thermal analysis of these solids indicated stability of the phase to 1000 degrees C. The photocatalytic activity of these compounds was investigated for the first time by the degradation of methylene blue. The degradation rates were similar for all compounds and comparable to that of commercial Degussa titania.