Tailoring Controllable Nanowire Morphologies Using a Multi-layer Porous Anodic Alumina Template for Technological Applications

Straight nanowires fabricated from single-layer porous anodic alumina (PAA) templates are known to be mechanically weak. To provide additional support, nanowires can be fabricated on multilayered PAA templates. In this work, Cu and Ni nanowires were fabricated using single-, double-, and three-layer PAA templates by pulse electrochemical deposition (PECD). The templates were made by anodizing Al-1 wt% Si and Al-0.5 wt% Cu thin films under different conditions. The morphologies of the PAA templates and fabricated nanowires were examined with scanning electron microscopy. The length of the nanowires was 3 μm, while the diameters ranged from 50 to 70 nm. The nanowires fabricated from a double-layered template (Al-0.5 wt% Cu/Al-1 wt% Si) were mechanically stronger with larger surface areas than those fabricated from an anodized Al-1 wt% Si template. The nanowires formed within the anodized Al-1 wt% Si layer had tree-like branches, while vertical nanowires with horizontal anchors were formed in the anodized Al-0.5 wt% Cu layer. The results also indicated that the volume expansion of the PAA template was controlled by depositing a Al-0.5 wt% Cu layer below the Al-1 wt% Si film. The Ni nanowires can be used as a platform for hydrogen production and in other technological applications.