Synthesis of Surfactant-free Aligned Single Crystal Copper Nanowires by Thermal-Assisted Photoreduction

A surfactant-free, template-less, and seed-less method for synthesis of aligned copper nanolawns has been demonstrated. Ultralong copper nanowires (50−200 nm in diameter, about 200 μm in length; aspect ratio > 1000) can be obtained through the combination of photoreduction of metallic ions (e.g., aqueous cupric chloride solution) on the surface of thin film titanium dioxide and blackbody radiation at 500 °C. The Cu nanowires (NWs) thus produced are single crystalline with a preferred [100] growth direction. The electrical behavior investigated using a nanomanipulation device indicates that the Cu NWs possess an excellent electrical resistivity of 18.57 μΩ-cm, which is the lowest value reported so far. It is also demonstrated that this thermal-assisted photoreduction (TAP) process is a novel method capable of synthesizing various one-dimensional metallic NWs, such as Cu, Ag, and Au, in large quantities.