The effect of sodium polyanethol sulfonate on the precipitation of zinc oxide

Abstract

A very strong effect of sodium polyanethol sulfonate (SPAS) on the formation and properties of ZnO particles was noticed. ZnO particles were prepared by hydrothermal treatment of zinc acetylacetonate in an aqueous medium in the absence or presence of SPAS. All prepared samples were characterized with the XRD, FE-SEM, FT-IR and UV/Vis techniques. Two different mechanisms are proposed for the formation of hollow ZnO particles. In the absence of SPAS ZnO rods were precipitated in the micron range, whereas in the presence of SPAS hexagonal ZnO particles with holes were obtained. The inner dissolution of hexagonal ZnO particles was promoted by the chemically active Zn-(0001) plane attacked by polyanethol sulfonate groups. By adding NH4OH to the precipitation system in the absence of SPAS, multipod (star-like) ZnO particles were formed. When SPAS was added to this precipitation system twin ZnO particles were formed and they were hollow inside. In this case the formation of ZnO particles was explained by the self-assembling mechanism supported by the presence of SPAS. Hexagonal and elongated ZnO particles were laterally arrayed. In this process the specific adsorption of polyanethol sulfonate groups played an important role. Determined were the band gap values of ZnO samples that are typical of “wet” precipitated ZnO.