Crystal-Growth Process of Single-Crystal-like Mesoporous ZnO through a Competitive Reaction in Solution

A novel crystal-growth system and morphology control of ZnO are achieved by using cetyltrimethylammonium chloride (CTAC), a general surfactant, in a new role. We synthesize ZnO via the layered hydroxide zinc acetate (LHZA) in ethanolic-aqueous zinc acetate solution. The CTAC surfactant plays three roles in the nucleation and crystal growth. First, it suppresses the formation of a strong concentration gradient in the solution. Second, it reduces the rates of nucleation and crystal growth of LHZA through diffusion-rate control in the solution. Finally, it expedites the formation of ZnO by increasing the solution pH. The competitive reaction, controlled by CTAC, between the nucleation and crystal growth of LHZA and the formation and crystal growth of ZnO results in the formation of a novel ZnO morphology. This morphology is composed of layered, nearly spherical particles, which are formed by the stacking of nanosheets with single-crystal-like, mesoporous structures.