Structural and photocatalytic activity of lanthanide (Ce, Pr, and Nd) molybdovanadates

Lanthanide (Ce, Pr, and Nd) molybdovanadates were synthesized by the solid-state method. These compounds crystallize in the tetragonal space group I4(1)/amd with a = b = 7.3750 (4) and c = 6.4867 (4) angstrom and Z = 4. The crystal structure has been analyzed by FTIR, UV-visible spectroscopy, and powder X-ray diffraction. Particle sizes are in the range of 300-400 nm as observed by scanning electron microscopy. Energy-dispersive X-ray analysis suggests the formation of Ln(0.95)Mo(0.15)V(0.85)O(4) (Ln = Ce, Pr, and Nd) and the Rietveld refinements of the powder X-ray data substantiate this observation. Thermal analysis of these solids shows stability of the phase up to 800 degrees C. These materials were investigated for photocatalytic activity by degrading different dyes such as methylene blue(MB), orange G (OG), Rhodamine B (RB), Rhodamine Blue (RBL) Alizarine Red S (ARS), and Remazol brilliant blue (RBBR) under solar and UV irradiation since they exhibited lower band gaps. The degradation rates for all the dyes show enhancement as compared to the commercial titania catalyst, Degussa P-25, both in UV and sunlight. These compounds degrade chlorinated phenols much faster than titania, which indicates selectivity toward chloro substitution.