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.