The cathodic electrodeposition of crystalline ZnO nanowires and amorphous FeO(OH) nanotubes in polycarbonate track-etched membranes with pore diameters of 50–200 nm is reported. Nitrate was used as a sacrificial precursor for the electrochemical generation of hydroxyl ions that raised the pH of the interior of the nanopore, leading to precipitation of a metal oxide or hydroxide phase. The crystalline and semiconducting ZnO phase formed directly above 60 °C at sufficiently high pH and led to the formation of dense nanowires with preferential (0001) orientation. The morphology of the wire could be influenced by the deposition temperature. Axially segmented gold–ZnO and silver–ZnO nanowires were made. In contrast, the iron hydroxide phase deposited inside the pore as a permeable gel that collapsed and transformed into hollow FeO(OH) tubes during drying. The as-formed nanotubes were amorphous and could be filled with nickel in a subsequent electrodeposition step, yielding core-shell nickel iron-oxohydroxide nanowires. The cathodic efficiency of nitrate reduction was low in both cases, suggesting that diffusional supply of metal ions may be the rate-determining step.

Templated electrodeposition was used to synthesize silver-zinc oxide nanowires and iron oxide (Fe2O3) nanotubes in polycarbonate track etched (PCTE) membranes. Metal/oxide segmented nanowires were made to produce hydrogen gas from a water/methanol mixture under ultraviolet irradiation. It was observed that gas production increased during irradiation. Iron oxide nanotubes were synthesized via a gel synthesis route, avoiding clogging of the membrane pores during growth. The nanotubes formed without thermal after-treatment. Transmission electron microscopy (TEM) analysis and selected area electron diffraction (SAED) revealed a completely amorphous iron oxide structure. By demonstrating the synthesis of photocatalytically active segmented nanowire and nanotubes without post-treatment steps, templated electrodeposition can be a versatile and low cost tool for nanowires with designed functionality or fast nanotube synthesis.