The Effect of Gum Arabic on the Nano / Microstructure and Optical Properties of Precipitated ZnO

The development of the nano/microstructure of ZnO particles precipitated from zinc acetylacetonate showed dependence on the presence of gum arabic. In the absence of gum arabic in near-neutral pH range ZnO rods, some of them hollow, precipitated, whereas in alkaline (NH4OH) medium the multipods (stars) were obtained. A strong effect of gum arabic was noticed both in the near-neutral pH range and in alkaline (NH4OH) medium. In both cases ZnO particles consisted of 1D subunits. The FT-IR spectra of ZnO particles precipitated in the presence of gum arabic showed the IR bands due to the residual content of this biopolymer. Gum arabic formed the corona on ZnO particles and played a key role in the precipitation process from nucleation to the final ZnO product. UV/Vis spectra were also recorded. The PL spectra of ZnO powders dispersed in pure ethanol were very similar. In the presence of ethanol characteristic peaks in the blue emission region were diminishing, thus softening the intrinsic defects responsible for this emission. It was assumed that this effect was due to the covering of oxygen vacancies (Vo) at the interface ZnO/C2H5OH with the oxygen atoms present in ethanol.