Shape-controlled hierarchical ZnO architectures: photocatalytic and antibacterial activities

A simple soft chemical approach has been successfully adopted for the synthesis of ZnO in spherical assemblies (SA), nanorods assemblies (NRA), cauliflower-like assemblies (CFA) and mushroom-like assemblies (MA). The morphology of self-assembled ZnO nanostructures composed of numerous nanocrystals has been confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). X-ray diffraction and optical studies suggest an anisotropic nature of ZnO and presence of structural defects in ZnO nanostructures, respectively. N2 adsorption–desorption isotherm curves of these nanostructures (except MA) indicate predominantly 3D-mesoporous nature. These nanostructures are useful for their potential application in photocatalytic degradation of organic dyes (e.g. methylene blue, Rhodamine B) and inhibition of bacterial growth (S. aureus). Among these ZnO architectures, CFA exhibits excellent photocatalytic and antibacterial activities. In addition, the inhibition of bacterial growth of S. aureus is more effective under UV light than in dark conditions.