Enhanced solar light driven photocatalytic degradation of organic dye using solution combustion synthesized CeO2-ZnO nanocomposites

CeO2 and CeO2-ZnO nanocomposites were synthesized by the solution combustion method. Cerium/Zinc nitrates and sucrose were used as an oxidizer and fuel, respectively. Structural, morphological and optical properties were studied using x-ray diffraction (XRD), a field emission scanning electron microscope (FESEM) and ultra violet–visible absorption spectroscopy. XRD results show that the prepared CeO2 has cubic structure, whereas the CeO2-ZnO composite has both cubic and hexagonal structure. The particle size was found to decrease from 11 nm to 7 nm on increasing the fraction of ZnO in CeO2-ZnO nanocomposites. Optical characterisation showed that the band gap of pristine CeO2 and CeO2-ZnO nanocomposites red shifted from 3.02 eV to 2.91 eV. FESEM analysis revealed porous-like morphology of CeO2-ZnO nanocomposites. Pristine CeO2 and CeO2-ZnO nanocomposites with ratios of 1:0.33, 1:0.5 and 1:1 were evaluated for their photocatalytic activity against the degradation of methylene blue (MB) under solar light for 90 min. The degradation efficiency was 51.1% for pristine CeO2 and CeO2-ZnO (1:1) shows more degradation efficiency (99.9%), when compared to other ratios. Photocatalytic degradation efficiency was increased with increase in ZnO concentration in nanocomposites. This is due to reduced bandgap and less recombination of photo-generated charge carriers