Controlled hydrothermal processing of ZnO powders in the presence of PVP

Abstract

In this study low-temperature hydrothermal processing was used for synthesis of ZnO powders with controlled morphology, from micro rods, via hexagonal prism-like to nano-spheres, by varying [Zn2+]/[OH-] molar ratio. The synthesized powders were characterized using XRPD, FE-SEM, UV-Vis diffuse reflectance and Raman spectroscopy. It is noticed that the modification of the particle size and morphology from nanospheres to micro-rods resulted in increased visible light absorption. Besides, the band gap energy of the synthesized ZnO powders showed the red shift (-0.20eV) compared to bulk ZnO. The enhanced visible light absorption of the ZnO powders is related to the existence of lattice defects and the particle surface sensitization by PVP.