Electrochemical fountain pen nanofabrication of vertically grown platinum nanowires

Local electrochemical deposition of freestanding platinum nanowires was demonstrated with a new approach—electrochemical fountain pen nanofabrication (ec-FPN). The ec-FPN exploits the meniscus formed between an electrolyte-filled nanopipette (‘the fountain pen’) and a conductive substrate to serve as a confined electrochemical cell for reducing and depositing metal ions. Freestanding Pt nanowires were continuously grown off the substrate by moving the nanopipette away from the substrate while maintaining a stable meniscus between the nanopipette and the nanowire growth front. High quality and high aspect-ratio polycrystalline Pt nanowires with diameter of ∼150 nm and length over 30 µm were locally grown with ec-FPN. The ec-FPN technique is shown to be an efficient and clean technique for localized fabrication of a variety of vertically grown metal nanowires and can potentially be used for fabricating freeform 3D nanostructures.