In Situ Structure Evolution from Cu(OH)₂ Nanobelts to Copper Nanowires

In situ structural evolution from Cu(OH)2 nanobelts to copper nanowires has been studied by transmission electron microscopy in a vacuum of 3 × 10-8 Torr. The decomposition follows the sequence of Cu(OH)2 → CuO → Cu2O → Cu. The decomposition from Cu(OH)2 to CuO is attributed to electron beam radiation damage. The reduction from CuO to Cu2O is attributed to heat-induced decomposition between 50 and 200 °C. For the Cu(OH)2 nanobelts synthesized using the copper grid with and without a carbon coating, the decomposition from Cu2O to Cu takes place between 200 and 300 °C and 300 and 600 °C, and the final Cu takes the forms of polycrystalline nanowires sheathed with graphitic carbon and nanoparticles, respectively. Therefore, because of the nanostructured nature of the nanowires and large surface area, introducing carbon into the sample synthesis can reduce the decomposition temperature by almost half. This study demonstrates a possible approach for creating metallic copper nanowires by heat-induced decomposition under vacuum at 300 °C or even lower.