A novel surfactant-free emulsion approach to ZnO microspheres with nanostructured surfaces

ZnO microspheres with nanostructured surfaces were prepared by a novel surfactant-free emulsion for the first time. SEM, XRD, CO2-TPD, size analysis and BET measurement were used to characterize the ZnO microspheres. The diameter of the ZnO microspheres was in a range of 13.2-18.4 μm. The surfaces of the ZnO microspheres were made of petal-like nanostructures with a petal thickness of 80 nm and a petal length in the range of 0.6-1.2 μm. The XRD analysis indicated that the ZnO microspheres were of hexagonal lattice. The specific surface area of the ZnO microspheres was about 23.6 m2 g−1. The ZnO microspheres with nanostructured surfaces had larger specific surface area and higher density of basic sites than the ZnO polyhedral particles prepared by the comparing experiment (via a conventional homogeneous precipitation route). A mechanism for the formation of the ZnO microspheres with nanostructured surfaces was discussed.