Site-Specific Controlled Growth of Coiled Lambda-Shaped Carbon Nanofibers for Potential Application in Catalyst Support and Nanoelectronics

Carbon nanofibers (CNFs), in particular branched ones, raise high interest because of their potential for nanoelectronics, catalyst presentation, and applicability as dry adhesives. Here, we present a facile method based on an open ethanol flame in a microchannel for the controlled growth of coiled lambda-shaped carbon nanofibers (cλCNFs). The cλCNFs consist of two coiled foot CNFs anchored to the substrate and a noncoiled head CNF. The number of twists in the helical structure of the foot CNFs is always the same number and in the opposite direction of rotation for a given cλCNF. The growth position of the cλCNFs on a substrate can be controlled by targeted deposition of nickel salt via an atomic force microscopy cantilever. An extensive characterization of the cλCNFs allows us to understand the growth process and to develop a model explaining the observed features of the structures. The presented facile but controlled fabrication process for cλCNFs offers a promising route for targeted synthesis of a novel carbon structure with chiral subcomponents for experimental and application use as in site-specific growth of branched CNFs for nanoelectronics or local presentation of catalysts.