Electrodeposition of Ti Nanowires on Highly Oriented Pyrolytic Graphite from an Ionic Liquid at Room Temperature

Abstract

Ti nanowires have been deposited electrochemically, with in situ monitoring by scanning tunneling microscopy, at the step edge of highly oriented pyrolytic graphite (HOPG) at room temperature from 0.24 M TiCl4 in the ionic liquid 1-butyl-3-methyl imidazolium bis((trifluoromethyl)sulfonyl)amide. To our knowledge, this is the first time that a transition metal nanowire has been prepared in this way, which is enabled by the wide electrochemical windows of ionic liquids. The formation of the first nanowire is induced at the step edge of the HOPG substrate at a potential of −1.0 V versus the [Fc]+/[Fc] redox couple; subsequent straight and highly aligned wires grow in parallel to the first. This cooperative nucleation process of nanowires is unusual and has not been reported before. Up to six wires grow at constant potential over a period of about 20 min. The wires exhibit a narrow width distribution of 10 ± 2 nm and have a length of more than 100 nm.