Facile one-step-synthesis of carbon wrapped copper nanowires by thermal decomposition of Copper(II)–acetylacetonate

Carbon wrapped copper nanowires with outer diameters between 100 and 200 nm and lengths ranging from 500 nm up to 10 μm were synthesized by thermal decomposition of Copper(II)–acetylacetonate in a closed, evacuated quartz ampule. The as-grown material consists of a single crystalline copper core wrapped by amorphous carbon. After a thermal treatment near the melting point of copper the carbon wrapped Cu-cable is transformed into an empty carbon nanotube with a spherical Cu particle attached to the end. Due to nanoscale dimension of this material wires a decrease of the melting point of Cu is observed within the carbon shell. We show that the Cu melts already at a temperature of 800 °C. To the best of our knowledge we report for the first time on the emptying of a metal filled carbon nanotube by a thermal treatment. This process is of great importance, e. g. for the application of such nanostructures as nanopipettes or nanocables. Besides, a reversible “filling-emptying process” can be very useful for certain applications.