Photocatalytic degradation of Reactive Black dye using ZnO-CeO nanocomposites.

This study presents the photocatalytic efficiency of ZnO-CeO nanocomposites for the degradation of a model Reactive Black (RB) dye. Nano-CeO was synthesized using cerium nitrate precursor solution via chemical precipitation. Synthesized nano-CeO was mixed with ZnO nanoparticles in different mass ratios to obtain ZnO-CeO heterojunction photocatalyst. The morphology of the nanocomposites was examined using transmission electron microscope (TEM). X-ray diffraction patterns of the CeO corresponded well with (1 1 1) plane of cubic-phase CeO. The band gap of the ZnO-CeO nanocatalyst synthesized was determined to be 3.08 eV, which was lower than that of the pristine CeO and ZnO powders, respectively. The results indicate that 1:1 wt. ratio ZnO-CeO nanocomposite provides about 85% RB degradation within 90 min under UV light under alkaline pH conditions. Degradation rate of RB dye achieved with ZnO-CeO nanocomposite was almost 1.5 times greater than that obtained with pristine ZnO. Increasing CeO ratio beyond 1:1 wt. ratio did not significantly increase RB degradation. The results demonstrate that addition of CeO to ZnO results in lowering its band gap energy and aids charge carrier separation resulting in enhanced oxidation of RB dye under UV light.