Ultralong Cd(OH)2 nanowires were fabricated in high yield by a convenient chemical method using alkali medium at room temperature without using any templates. The preparation conditions induce a unilateral growth of nanowires, despite the absence of any template. The length of the nanowires reached several hundreds of micrometers, giving an aspect ratio of a few thousands. The X-ray diffraction shows that the Cd(OH)2 nanostructures crystallized in the wurtzite structure without any special orientation. The photoluminescence spectrum of Cd(OH)2 nanostructures appears as two emission bands: one related to green emission at 475–510 nm, and the other related to deep level emission at 510–540 nm. Also the formation mechanisms of the nanowires are presented. The growth mechanism involves the irreversible and specifically oriented selfassembly of primary nanocrystals and results in the formation of the nanowires.
