Synthesis and growth mechanism of ZnO rod-like nanostructures by a microwave-assisted low-temperature aqueous solution route

A zinc oxide (ZnO) nanoarray (rod-like nanostructure) was successfully synthesized through a low-temperature aqueous solution and microwave-assisted synthesis using zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and hexamethylenetetramine (HMTA) as raw materials, and using FTO glass as substrate. The effects of parameters in the preparation process, such as solution concentration, reaction temperature and microwave power, on the morphology and microstructure of ZnO nanoarray were studied. Phase structure and morphology of the products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results indicated that hexagonal wurtzite structure ZnO nanoarray with good crystallization could be prepared through a low-temperature solution method. When the concentration of the mixed solution was 0.05 M, the reaction temperature was 95 °C, and the reaction time was 4 h, high-density ZnO regular nanorods of 200 nm diameter were obtained. A possible mechanism with different synthesis methods and the influence of microwave processing are also proposed in this paper.