Free-standing ZnO nanorods and nanowalls by aqueous solution method.

Large quantity of free-standing ZnO nanorods and nanowalls were synthesized at low temperature of below 100 degrees C using zinc acetate, zinc nitrate hexahydrate, and hexamethylenetetramine by using a simple aqueous solution method. The general morphology of the grown ZnO nanostructures which include nanorods and nanowalls was strongly influenced by growth conditions. It was found that the grown ZnO nanorods are of a single-crystalline hexagonal structure and preferred c-axis growth orientation. ZnO nanorods were of better crystallinity than ZnO nanowalls, due to the higher growth temperature used to grow ZnO nanorods. Strong free exciton emission bands with relatively weak deep level emission were clearly observed from ZnO nanorods and nanowalls, indicating their good optical properties.