Investigations on the hydrothermal preparation of shape-engineered zinc oxide nanostructures

Investigations are made on the effective chemical ambience and physical conditions in the hydrothermal method for the engineering of various shapes of ZnO nanostructures having different aspect ratios. Different zinc-ion sources are chosen and their reaction with hexamethylenetetramine, NaOH, triethanolamine etc. , separately and in combinations, are exploited for shaping a variety of nanostructures, such as nanotubes bunches, spheres, dumbbell-like hexagonal rods, nano-flakes, of larger surface area and higher aspect ratio by varying the pH of the solution and altering the generation of zinc metal ions or its metal-hydroxide complexes. The reaction mechanisms for the formations of a variety of nanostructures are discussed on the basis of energy minimization, interfacial tension and the growth kinetics of formation.