Solvothermal synthesis of ZnO spheres: Tuning the structure and morphology from nano- to micro-meter range and its impact on their photocatalytic activity

Abstract

Nano- and micro-sized ZnO spheres were fabricated via a simple solvothermal synthesis using two different precursors, while diethanolamine was used to control the morphology. The applied solvent composition, precursor ratio and solvothermal treatment temperature were mathematically correlated with the diameter of spheres. The crystallite size could be easily controlled by adjusting the temperature, providing flexibility during synthesis. The photocatalytic activity and its dependence on the unique morphology were investigated via the decomposition of phenol model pollutant. It was revealed that the surface proprieties were more defining than the secondary particle size in this regard. A surprising synergic effect was observed between the ratio of exposed crystallographic planes of (100) and (002) and crystallite size upon the activity, while the size of the spheres shows little influence. The presented method enables the flexible design of ZnO photocatalysts with spherical morphology in a tunable size range.