Improved photocatalytic degradation of RO16 dye using hydrothermally synthesized CeO2@ZnO nanocomposite

The structural, microstructural, optical and photocatalytic properties of hydrothermally obtained single-phase ZnO and CeO2@ZnO nanocomposites have been investigated by the XRPD, FESEM, HRTEM/SAED and UV-vis techniques. In order to improve the photocatalytic efficiency of ZnO, the optimal CeO2 content in ZnO powders was determined by varying the quantity of CeO2 from 0 to 10 mol%. The results showed that CeO2 with spherical crystallites of about 5 nm was distributed onto the ZnO surface, whose crystallites displayed a bimodal distribution, from nano- to microcrystallites. The morphology of ZnO particles varied from elongated nanograins to microrods that further formed a 3-D tie-like morphology which was disrupted by CeO2 adding. By degrading 90% of RO16 dye in 180 minutes, the composite containing 5 mol% of CeO2 showed approximately for 30% better photocatalytic efficiency comparing to other samples, although all the obtained powders have similar structural, microstructural and optical characteristics. This is obviously the optimal ratio of these two phases, in which synergy of CeO2 adsorption and ZnO photocatalytic effect reaches its maximum due to reduced recombination rate and improved adsorption. The kinetic of RO16 degradation could be described by a pseudo-first order model.