Templated electrosynthesis has widely been employed to prepare solids of defined dimension.[1] Here we illustrate how electrochemistry can be employed to manage the pH within the pores of a template and demonstrate that controlled growth of continuous SnO₂ nanotubes can be achieved. A gold electrode modified with a porous polycarbonate membrane was immersed in an aqueous tin dichloride solution. Electrochemistry was employed to control the local pH within the pores and drive a precipitation reaction. Removal of the gold and dissolution of the membrane yielded polycrystalline tin oxide nanotubes. The crystallinity of the as-deposited material was enhanced by annealing in ambient. It is proposed that the formation of nanotubes results from continuous side-wall precipitation along a reaction front. The nanotube size was controlled by using templates with different diameters and deposition time. Metal@SnO₂ core-shell nanostructures were fabricated after a further electrodeposition of metals within the SnO₂ nanotubes. We formed 1-D metal oxide composites by annealing as-prepared materials in air.

[1] J.C. Hulteen, C.R. Martin, J. Mater. Chem. 7 (1997) 1075.