Growth of ZnO nanoparticles prepared from cost effective laboratory grade ZnO powder and their application in UV photocatalytic dye decomposition

ZnO nanoparticles were prepared by mechanical grinding of laboratory grade ZnO powder. These nanoparticles were characterised by using X-ray diffraction analysis, transmission electron microscopy (TEM), photoluminescence and diffuse reflectance spectroscopy. From TEM study it reveals that the particles mostly show one dimensional morphology. The average length and diameter of these nanoparticles are 300 nm and 59.34 nm respectively. Studies on UV photocatalysis behaviour of these nanoparticles were done through their use in methylene blue dye decomposition. Particularly, the reaction kinetics and reaction rate are estimated by monitoring the dye decomposition activity with respect to UV exposure time. The kinetic is found to be pseudo-first order with the reaction rate constant (kinetic constant) 0.18 min⁻¹. In the comparative study it has been demonstrated that these ZnO nanoparticles can show three times higher dye degradation activity with respect to benchmark commercial nanoparticle P25. From the photocatalysis studies with scavengers like Isopropyl alcohol and ethylenediaminetetraacetate it is demonstrated that hole (h⁺) and hydroxyl radical (^·OH) have a vital role in the dye decomposition activity. The used ZnO powders are of extremely low cost, so this material can be found to be a better choice for photocatalytic dye decomposition applications.