Oriented growth of metal and semiconductor nanostructures within aligned mesoporus channels

In the present work, we show how different types of inclusion chemistry can be used to generate oriented, high-aspect-ratio metal and semiconductor nanowires in insulating silica host structures prepared within anodic alumina membranes (AAMs). The structural features of the Pluronic123-templated silica filaments in the AAMs with their intriguing columnar and circular arrangement of mesopores allow for the inclusion of a variety of aligned ID nanostructures ranging from metallic (Pt, Au, and Pd) and semiconductor (Ge) to carbon nanotubes and filaments. The synthetic techniques include wet chemical impregnation and reduction in precalcined mesopores, impregnation of surfactant-containing mesopore systems, and mass transport via supercritical fluid deposition in surfactant-containing mesopores. Important issues such as the crystallinity and continuity of the encapsulated wires as a function of material and deposition technique have been discussed.