Template-free synthesis of hexagonal ZnO disk and ZnO–Ag composite as potential photocatalyst

Stable hexagonal ZnO disk and ZnO–Ag composites with various percentages of Ag contents were prepared through a simple, easily reproducible and template free path, assisted by hexamine. Here, centrifugation speed and calcination temperature played a crucial role to segregate hexagonal disks of ZnO exclusively from some unwanted morphologies. The impregnation of Ag nanoparticles on ZnO surface was established after modifying the surface with oleic acid. Oleic acid played the role of anchor to hold Ag nanoparticles site-selectively on ZnO surface. Pristine ZnO and the composite both were tested for their light induced activities towards methylene blue dye degradation. The performance indicated that an optimized amount of Ag nanoparticles on ZnO matrix could maximize the performance, beyond which activity was suppressed. All the samples were thoroughly characterized using UV–Vis spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Thermogravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction Analysis (XRD), X-ray Photoelectron Spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) isotherm