Synthesis of high surface area ZnO powder by continuous precipitation

Synthesis of high surface area ZnO powder was achieved by continuous precipitation using zinc ions and urea at low temperature of 90 °C. The powder precipitated resulted in high-purity single-phase ZnO powder when calcined at 280 °C for 3 h in air. The solution pH and the precipitation duration strongly affected the surface area of the calcined ZnO powder. Detailed structural characterizations demonstrated that the synthesized ZnO powder were single crystalline with wurtzite hexagonal phase. The powdered samples precipitated by homogeneous precipitation crystallized directly to hydrozincite without any intermediate phase formation.The phase structures, morphologies and properties of the final ZnO powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), dynamic light scattering particle size analysis (DLS), and nitrogen physisorption in order to determine the specific surface area (BET) and the pore size distribution (BJH).

Graphical abstractHigh surface area ZnO powders are synthesized by a low temperature continuous precipitation under ultrasonication. Urea is used as precipitating agent so that no contamination of ZnO powder emanating from precipitating agent, such as, alkalis, is observed. pH and type of precursor greatly affects the surface area and other properties. In this manuscript, we report a very simple and effective continuous precipitation to synthesize high surface area ZnO powder.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The synthesis of high surface area ZnO powder was achieved at 90 °C in a continuous precipitation unit. ► Continuous precipitation unit was ultrasonicated to improve final product homogeneity. ► Precipitation intermediate, hydrozincite, was led to high surface area ZnO powder. ► The synthesized ZnO nanoparticles had a rather uniform mesoporous structure.